Abstract
Intestinal parasitism impact on skeletal development is poorly characterised. This study examined whether infection with Eimeria spp. disrupts bone and cartilage homeostasis in rapidly growing broiler chickens. Male Ross 308 chicks were randomly assigned to control or infection groups. On day 20 post-hatch, infected birds received a mixed oral inoculum of Eimeria spp.; controls were sham-dosed and euthanised 22 days later. Tibial osteometry, densitometry, strength, mineral composition and histomorphometry were assessed. Serum markers of bone turnover and inflammation were measured. Infection reduced maximum elastic strength, ultimate strength and elastic energy of the tibia. Trabecular bone volume fraction and thickness declined, whereas trabecular separation increased. The proportion of thin collagen in trabecular, cortical and articular tissues was reduced. Articular cartilage exhibited thinning of the superficial and deep zones and diminished proteoglycan staining. Mineral analysis revealed a lower Ca:P ratio and elevated copper and sulfur content. Serum IGF-1 decreased, while osteoprotegerin, IL-1β, IL-6, IgY, IgM and ceruloplasmin increased. These results demonstrate that Eimeria infection can secondarily compromise skeletal development through inflammatory and metabolic pathways. The broiler model therefore offers a tractable platform for investigating infection-associated, inflammation-driven bone loss relevant to paediatric and post-infectious osteopathies.
Introduction
Approximately one-third of the global population is infected with parasites, with the highest infection rates occurring in developing countries and lower rates in more developed urban regions1. Several species of parasitic protozoa can cause gastrointestinal infections in humans. Cryptosporidium spp., Cyclospora cayetanensis, and Cystoisospora belli (formerly Isospora belli) are classified within the Coccidia subclass. Cryptosporidium belongs to Apicomplexa, whereas Cyclospora and Cystoisospora are placed in the Eimeriorina clade; these assignments remain fluid as morphology and genomics are re-evaluated2.
Cyclospora cayetanensis infects exclusively humans, with all attempts to establish animal infections having failed; thus, there are no established animal models. Nevertheless, this parasite is frequently referred to in the literature as “human Eimeria"3. Both C. cayetanensis and Eimeria spp. are highly similar in terms of pathogenesis and genomic structure4.
Few studies exist in the literature regarding the impact of parasitic infections on the human skeletal system5. Eimeria infects numerous animal species, particularly chicken broilers3. Consequently, broilers represent a suitable animal model that may facilitate a better understanding of the pathogenesis and effects of C. cayetanensis infections in humans. Studies confirm that broiler chickens are appropriate models for preclinical growth experiments6. Due to their rapid growth rate, reaching somatic maturity by approximately 42 days, broilers allow researchers to observe skeletal metabolic changes within a short time frame. Therefore, these animals are commonly utilized in bone and cartilage research7,8. They are also employed as models for assessing the impact of nutritional deficiencies on skeletal development in children6. Previous research indicates the potential use of broiler chickens as models for evaluating how parasitic infections affect bone and cartilage homeostasis9.
Recent years have seen numerous studies exploring the use of parasitic infections to treat metabolic syndrome, including obesity, insulin resistance, and type II diabetes. However, initial results indicate that therapeutic efficacy depends on parasite species and inoculum size; excessive parasitic burden can itself induce severe side-effects1,10. Only limited research addresses how gastrointestinal disturbances resulting from parasitic infections influence the functioning of other organ systems and disease development. Osteoporosis (OP) and osteoarthritis (OA) are multifactorial conditions influenced by metabolic syndrome11. Given the contradictory findings from various studies regarding the effects of parasitic infections on the secondary, age-independent bone loss/osteopenia using different experimental models, further research is warranted5,12,13,14.
Eimeria spp. invade and replicate within enterocytes of the small intestine, eliciting a pronounced inflammatory response and oxidative stress that compromise gut integrity and impair nutrient absorption critical for skeletal development15. Available short-term studies in chickens (up to six days post-infection) have reported reduced bone mineral density (BMD) with no significant changes in bone geometry; however, alterations in dynamic histomorphometry suggest that more pronounced effects on bone structure may emerge at later stages of infection9,16. Mechanical strength data are currently lacking. Although direct investigations of cartilage effects are also unavailable, the systemic inflammation characteristic of coccidiosis is likely to impair chondrocyte function and extracellular matrix formation in growing individuals, underscoring the need for focused studies on cartilage integrity as well.
Thus, the present study employed broiler chickens infected with Eimeria spp. as a tractable, bipedal in vivo model for human-relevant, inflammation-driven bone disease. Like humans, chickens are bipedal, placing comparable mechanical loads on the tibio-femoral joint, while their rapid growth and high basal metabolism enable observation of chronic active degenerative processes in a relatively short timeframe. This heavyweight chicken model offers several advantages over quadrupedal species: bipedal gait exposes joints to greater mechanical stresses and large joints facilitate detailed analysis, making them ideal for skeletal investigations17. Importantly, the cytokine drivers of bone resorption and cartilage degradation are conserved across avian and mammalian species, with recent evidence demonstrating that gastrointestinal diseases, including intestinal infections, affect bone tissue via identical immunological pathways in both chickens and humans, directly linking gut inflammation to skeletal loss18. To our knowledge, no prior work has directly evaluated in a single avian study the combined effects of Eimeria infection on bone densitometry, three-point bending strength, geometric and material properties, histomorphometry of trabecular and articular collagen, and serum markers of bone turnover and inflammation. By integrating these endpoints, we fill a critical gap in understanding how gut parasitism can secondarily impair skeletal homeostasis, a paradigm with clear implications for pediatric and post-infectious osteopathies in humans.
Results
Infection with Eimeria spp. did not induce significant changes in the basal osteometric parameters of the tibia (Fig. 1A).
Likewise, no inter-group differences were detected in mid-diaphyseal geometric parameters (Fig. 1B).
In contrast, histomorphometric analysis demonstrated that Eimeria infection significantly reduced bone-volume fraction (BV/TV; p < 0.001) and trabecular thickness (Tb.Th; p = 0.010), while increasing trabecular separation (Tb.Sp; p = 0.013) and trabecular number (Tb.N; p = 0.006) relative to controls (Fig. 1C and D).
(A) Osteometric properties and bone tissue density of the tibia in studied animals. (B) Geometric properties of the tibia mid-diaphysis. (C) Histomorphometric parameters of trabecular bone in the proximal metaphysis. (D) Representative images of PSR-stained bone trabeculae. Control – healthy birds. Study – birds infected with Eimeria spp. MRWT – mean relative wall thickness; CSMI – cross-sectional moment of inertia; BV/TV – the bone volume; Tb.Th – trabecular thickness; Tb.Sp – trabecular separation; Tb.N – trabecular number. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Scale bars represent 40 μm. Statistical significance is indicated as: ** p < 0.01; *** p < 0.001 (two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com and Affinity Photo version 1.10.6, Sherif Ltd., Nottingham, UK, htts://affinity.sherif.com.
Parasite infection markedly impaired the structural integrity of the tibia. Significant reductions were observed in maximum elastic strength (p = 0.004), ultimate strength (p = 0.002), and elastic energy (p = 0.037) in infected birds (Fig. 2A).
Material properties, however, remained unchanged between groups (Fig. 2B).
The influence of Eimeria spp. infection on mechanical properties of the tibia in studied animals. (A) Bone structural properties. (B) Material properties. Control – healthy birds. Study – birds infected with Eimeria spp. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Statistical significance is indicated as: * p < 0.05; ** p < 0.01 (determined by two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com.
No significant differences were found in overall densitometric indices or ash percentage of the tibiae (Fig. 3A).
Calcium and phosphorus contents were comparable between groups, but the Ca/P ratio was modestly lower in infected birds (p = 0.028; Fig. 3B). Among other minerals, copper (p = 0.008) and sulfur (p < 0.001) concentrations were elevated in the Eimeria group, whereas all remaining macro- and micro-elements were unaffected (Fig. 3C).
The influence of Eimeria spp. infection on the densitometric properties, bone ash content and bone mineral components in the studied animals. (A) Densitometric indices and ash content; (B) Content of calcium, phosphorus and Ca/P ratio; (C) Content of zinc, copper, iron, magnesium, and sulfur. Control – healthy birds. Study – birds infected with Eimeria spp. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Statistical significance is indicated as: * p < 0.05; ** p < 0.01 ; *** p < 0.001 (determined by two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com.
Safranin O-stained sections (Fig. 4A) revealed diminished proteoglycan content in the superficial zone and around vascular channels of the transitional zone in infected birds. Morphometric assessment confirmed significant thinning of both the superficial (p = 0.011) and deep (p < 0.001) zones, while the transitional zone was unaltered (Fig. 4B).
The influence of Eimeria spp. infection on articular cartilage morphology in the studied animals. (A) Representative images of Safranin O-stained sections of articular cartilage; (B) Zone-specific cartilage thickness. Control – healthy birds. Study – birds infected with Eimeria spp. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Scale bars represent 400 μm. Statistical significance is indicated as: ** p < 0.01; *** p < 0.001 (determined by two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com and Affinity Photo version 1.10.6, Sherif Ltd., Nottingham, UK, htts://affinity.sherif.com.
Picrosirius red (PSR) staining (Fig. 5A) showed a pronounced loss of thin (green birefringent) collagen fibres in infected animals. Quantitatively, thin collagen content was significantly reduced in trabecular bone and cortical bone (all p < 0.001; Fig. 5B).
The influence of Eimeria spp. infection on content of thin collagen content of the tibia in studied animals. (A) Representative photos of the of PSR-stained section of trabecular bone and compact bone (thin collagen appears green under polarized light, arrowhead); (B) Percentage of thin collagen relative to total collagen. Control – healthy birds. Study – birds infected with Eimeria spp. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Scale bars represent 200 μm. Statistical significance is indicated as: *** p < 0.001 (determined by two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com and Affinity Photo version 1.10.6, Sherif Ltd., Nottingham, UK, htts://affinity.sherif.com.
Serum analyses of bone turnover markers demonstrated lower IGF-1 (p = 0.002) and higher osteoprotegerin (p = 0.001) concentrations in infected birds (Fig. 6A). Pro-inflammatory cytokines interleukin (IL) -1 (p = 0.031) and IL-6 (p = 0.010) were increased (Fig. 6B), as were immunoglobulins (Ig) Y and IgM (both p < 0.001; Fig. 6C). No differences in Ca or P content, or in the Ca: P ratio, were observed between the study groups (Fig. 6D). Ceruloplasmin was also elevated (p = 0.002), and calcitriol levels were unchanged (Fig. 6E).
The influence of Eimeria spp. infection on blood biomarkers. (A) Bone turnover markers; (B) Pro-inflammatory cytokines; (C) Immunoglobulins; (D) Serum levels of Ca, P, and Ca: P ratio; (E) Ceruloplasmin and calcitriol [1,25(OH)2D3]. Control – healthy birds. Study – birds infected with Eimeria spp. IGF-1 – Insulin-like growth factor 1; TNF-α – tumor necrosis factor alfa; IL-1 – interleukin-1; IL-6 – interleukin-6; IgY – immunoglobulin Y; IgM – immunoglobulin M. Values represent means ± standard deviation (SD, whiskers) from n = 10 birds per group. Statistical significance is indicated as: * p < 0.05; ** p < 0.01; *** p < 0.001 (determined by two-tailed Student’s t-test, t-test with Welch’s correction, or Mann–Whitney U test). Figure was generated in GraphPad Prism version 10 for Windows, GraphPad Software, San Diego California USA, https://www.graphpad.com.
Discussion
Although bone and cartilage are recognised as fundamental to overall health, the impact of secondary skeletal disorders, that is, OP or OA arising from chronic disease, systemic inflammation or infection, remains poorly characterised5. During growth, bone and cartilage remodel continuously to secure proper longitudinal elongation and mineral accrual19. Bone homeostasis requires tight coupling between osteogenesis and osteolysis; disruption of this balance produces pathology, manifesting as secondary OP when resorption out-paces formation or as osteopetrosis when formation predominates20,21. Likewise, a shift between cartilage matrix synthesis and degradation promotes fibrillation, subchondral ossification and osteophyte formation, hallmarks of OA22.
Unlike primary (age-related) OP/OA, secondary forms can occur at any life stage, including childhood and adolescence, whenever inflammatory mediators, endocrine disturbance or malabsorption interfere with normal skeletal turnover23. Gastro-intestinal disorders, endocrine diseases and chronic infections have all been linked to such inflammation-driven bone loss/osteopenia and cartilage degeneration24,25. Low-grade systemic inflammation characteristic of metabolic syndrome (obesity, type-2 diabetes) is now recognised as a major driver of secondary OA, while intestinal malabsorption in coeliac disease or inflammatory bowel disease predisposes to secondary OP26.
Parasitic infections belong to this spectrum: enteric protozoa can impair nutrient uptake and evoke cytokine cascades that uncouple bone remodelling27. Conversely, helminths that skew host immunity toward an anti-inflammatory Th2 profile have shown protective, or even therapeutic, effects in experimental models of metabolic syndrome and inflammatory arthritis28,29. These divergent outcomes underscore that skeletal consequences of parasitism depend on parasite species, inoculum size and host immune status1,10. Clarifying how specific parasites perturb, or sometimes preserve, bone and cartilage homeostasis is therefore essential for understanding secondary OP/OA across the lifespan.
Our analysis of osteometric properties revealed that infection with Emeira spp. had no significant effect on the length or thickness of the tibia in the studied animals. In contrast, Lee et al. (2017) observed different results in animals infected during growth and development. In that study, 3-week-old mice were infected with Plasmodium, and some animals euthanized at 6 weeks of age exhibited significantly shorter femurs compared to the control group. Notably, a subset of animals treated for the parasitic infection and euthanized at 9 weeks of age demonstrated a restoration of normal bone length. These findings suggest that parasitic infection during growth and development can adversely affect the skeletal system, potentially contributing to skeletal defects12. In our study we did not observe significant differences in the lengths of the examined bones between the groups. This discrepancy may be attributed to the different parasite species employed in our study. Moreover, research assessing the impact of parasites on metabolic syndrome has demonstrated that infections with flukes and Schistosoma spp. exert more beneficial effects on the host compared to intestinal parasites, as they appear to mitigate the adverse immune response10. These observations underscore the critical role of parasite species in influencing host outcomes, analogous to the specificity required in targeted therapies.
In our study, we did not observe differences in the densitometric properties of the examined bones between groups. However, a few existing studies report conflicting results5,12,30. For instance, Li et al. (2021), investigating 8-week-old male mice infected with Schistosoma spp, found a significant decrease in bone mineral density (BMD) compared to uninfected controls. Notably, they assessed the animals 11–13 weeks after infection, and the mice were already 8 weeks old at the time of infection—an age at which they had reached somatic maturity5. In contrast, our study infected broiler chickens at 20 days of age and collected bones at 42 days, which may explain the differences in findings. Likewise, Lee et al. (2017) demonstrated that long-term Plasmodium infection negatively affects bone mass12. Zhu et al. (2022), examining 729 patients with low BMD (413 diagnosed with osteoporosis and 316 with osteopenia), found that 113 were infected with T. gondii, which was associated with an increased risk of osteoporosis, particularly its more complex forms30. These observations—along with those by Li et al. (2021)—show that the duration and timing of infection critically influence the skeletal system5,12,30. Furthermore, Lee et al. (2017) also observed detrimental effects on bone even in short-term Plasmodium infections, underscoring the importance of the parasite species involved12. The health status of the host at the time of infection is another key factor. Studies using collagen-induced arthritis (CIA) models infected with Schistosoma japonicum or treated with parasite-derived products noted a protective effect that inhibited bone loss, presumably due to the parasite’s immunomodulatory action and the resulting mitigation of systemic inflammation29,31. It should also be noted that our research was conducted in animals undergoing active growth, whereas most of the cited experiments involved fully mature organisms. Overall, our findings and those from the literature highlight how the parasite species, whether live parasites or their products are used, infection duration, age at infection, and host health status all significantly influence the impact of parasitic infections on skeletal homeostasis.
Despite the lack of differences in the densitometric properties of the examined tibiae, our analysis of the mineral fraction composition revealed the influence of Eimeria spp. infection on the Ca: P ratio and the levels of certain minerals. Specifically, we observed a significant decrease in the Ca: P ratio accompanied by an increase in sulfur and copper content. These changes may stem from the histopathological alterations caused by Eimeria spp. In the intestinal epithelium, where the parasites destroy epithelial cells lining the gastrointestinal lumen, trigger inflammation, and consequently impair nutrient absorption. Such disruptions in the gastrointestinal environment also affect resident microorganisms3,32, and it has been shown that parasitic infections can negatively influence micronutrient uptake1. However, in our study none of the infected broilers developed clinical diarrhea or any evidence of malnutrition, feed intake and growth performance paralleled those of control birds, ruling out bulk malabsorption as the primary driver of mineral imbalance. Moreover, serum Ca and P (and Ca: P) measured on day 42 did not differ between groups, indicating comparable systemic mineral status and arguing against bulk dietary malabsorption as the primary driver of the bone mineral imbalance. Instead, the decline in the bone Ca: P ratio aligns with patterns reported in inflammation-mediated osteopenia/secondary osteoporosis, where cytokine-induced bone resorption outpaces matrix mineralization; in contrast, primary, age-related osteoporosis does not typically feature a lowered Ca: P ratio33,34. Thus, in our model, the reduced bone Ca: P most likely reflects an inflammatory uncoupling of bone remodeling rather than simple dietary or diarrheal malabsorption.
As mentioned earlier, the analysis of bone mineral fractions carried out in this study showed an increase in sulfur content. Elevated sulfur levels in bones of Eimeria-challenged chickens may reflect increased mobilization and utilization of sulfur amino acids (methionine and cysteine) as an adaptive response to infection-induced oxidative stress9. Recent studies have proposed that dietary supplementation of sulfur amino acids could be beneficial for bone health under Eimeria challenge due to their potent antioxidant capacity and role in glutathione synthesis35. Since both treatment groups in our study received identical diets without SAA (sulfur-containing amino acids) supplementation, the observed increase in bone sulfur content suggests an endogenous metabolic response where the organism naturally mobilizes sulfur-containing compounds to combat coccidiosis-induced oxidative damage at bone sites. This finding supports the hypothesis that sulfur amino acids may indeed be critical for maintaining bone health during coccidial infections, providing physiological evidence for the potential benefits of SAA supplementation strategies.
It should be noted, however, that available literature lacks data on changes in bone strength, geometric, and structural properties resulting from Eimeria spp. infection in humans, and there are no studies examining the impact of this parasitic infection on collagen structure or the mineral content of bone tissue. Our research is the first to address these properties, offering new insight into how Eimeria spp. may influence skeletal homeostasis.
Statistical analysis of our results revealed a significant decrease in maximum elastic strength, elastic energy, and ultimate strength in the infected group, even though no changes were found in the geometric or structural properties of cortical bone, which may be related to the observed decrease in the Ca: P ratio36. However, it is also well known that bone strength depends on the quality and structure of the organic matrix, which is primarily composed of collagen fibers that form the scaffold for mineral components37,38. Consequently, the decline in strength properties we observed also may be linked to changes in collagen composition. Our findings showed a significant reduction in the amount of thin collagen fiber. This pattern suggests a reduction in osteogenesis and a predominance of osteolysis, likely weakening the organic fraction of bone and contributing to decreased mechanical strength39.
The depletion of thin collagen fiber observed here is compatible with cytokine-mediated suppression of osteoblasts and stimulation of osteoclastic activity, as both IL-1β and IL-6 down-regulate Runx2 (RUNX family transcription factor 2) and COL1A1 (collagen type I alpha 1 chain) while enhancing osteoclasts expression in various in vivo and in vitro models40,41. On contrary, a very recent study showed that osteogenesis-related gene expression in broilers bone marrow was not affected by Eimeria ssp. infection, and the changes in mRNA of osteoclastogenesis-related gene expression was limited, but the analyses were peformed 6 days post infections9. Overall, these findings highlight a complex, temporally dependent interplay between pro-inflammatory cytokines and bone remodeling in Eimeria-infected animals: while IL-1β and IL-6 clearly drive early suppression of osteoblast differentiation and enhanced osteoclastic resorption—manifested as thin collagen depletion, early-stage analyses (e.g., six days post-infection) may underestimate transient osteogenic disruptions.
Changes to collagen structure could also explain the increase in copper content in the inorganic fraction, since copper stimulates the synthesis of collagen fibers42. To our knowledge, the observation of changes in copper content in the mineral fraction is a new aspect in studies evaluating the impact of parasitic infections and changes in gastrointestinal homeostasis and their impact on bone tissue. The increase in copper content may also be associated with an increase in serum ceruloplasmin, which contains most of the copper in blood plasma, indicating disturbances in copper homeostasis and distribution in the body. During the acute-phase response, hepatically synthesised ceruloplasmin sequesters the majority of circulating copper and redirects it to peripheral tissues, leading to elevated copper deposition in bone. This increase in bone copper may have dual and even opposing consequences for skeletal homeostasis. On one hand, excessive copper can be cytotoxic to bone progenitors, as high copper levels inhibit the differentiation of marrow mesenchymal stem cells into osteoblasts43, impair osteoclast resorption44, and generate reactive oxygen species that damage marrow stromal cells and collagen matrices45. On the other hand, copper is an essential cofactor for lysyl-oxidase (LOX), the enzyme that catalyzes collagen cross-linking, and increased copper deposition in cartilage and synovium correlates with early osteoarthritic changes in Wilson’s disease46. Similarly, studies report elevated cooper in severely worn human cartilage, interpreted as a compensatory response to promote collagen repair and cross-linking. Furthermore, copper has been shown to reduce the severity of developmental cartilage lesions by enhancing type II collagen synthesis and cross-link density47. Taken together, these findings suggest that the copper elevation in our Eimeria model might simultaneously hinder bone regeneration through MSC and osteoclast dysfunction while attempting to reinforce collagen matrices via LOX activation. Disentangling these contrasting effects will require targeted in vivo manipulations of copper bioavailability and LOX activity in future studies of secondary, inflammation-induced osteopathy.
Infection of the studied animals with Eimeria spp. led to notable histomorphometric changes in trabecular bone, including reductions in BV/TV and Th.Tb, coupled with increases in Tb.N and Th.Sp. We also recorded a significant decrease in the amount of thin collagen. Negative effects on trabecular bone histomorphometry following parasitic infection were reported by Lee et al. (2017) and Li et al. (2021)5,12. Li et al. (2021) observed decreases in Th.N, Th.Tb, and BV/TV, with no changes in Th.Sp, whereas Lee et al. (2017) documented decreases in Th.N and BV/TV alongside an increase in Tb.Sp. Both studies focused on adult mice, although Lee et al. (2017) additionally examined 6-week-old mice and found that a 3-week infection significantly reduced BV/TV, a change that persisted in some animals even after treatment. These findings underscore the lasting detrimental effects of parasitic infections on skeletal development5,12. It should also be noted that our study was conducted on rapidly growing chickens during growth and development, while the studies discussed here were conducted on adult mice5,12. However, regardless of the experimental model used, it can be observed that parasitic infections negatively impact bone trabeculae.
In our work, the infection likewise negatively impacted trabecular bone histomorphometry, although an increase in Tb.N was noted, possibly reflecting an adaptive response by the skeletal system to altered conditions. Li et al. (2021) further demonstrated that changes in trabecular bone could be linked to higher osteoclast activity, indicated by elevated CTx (C-terminal telopeptide) in infected animals, while OC levels remained unchanged5. We also observed no changes in OC but noted elevated levels of OPG, produced by osteoblasts to suppress osteoclast-mediated bone resorption via RANK inhibition48. These findings suggest that bone resorption may initially have prevailed—evident in reduced BV/TV, thinner trabeculae, and increased spacing. In response, heightened OPG production likely served to re-establish balance, increasing the number of trabeculae. However, the trabeculae remained thinner, and lower levels of thin collagen point to a continued predominance of resorption over new bone formation, ultimately compromising bone quality.
Studies inducing joint inflammation in animals have reported results that differ from those in our work and in the investigations by Lee et al. (2017) and Li et al. (2021)5,12. Specifically, these inflammation-based studies have shown that parasitic infections can exert a protective effect on trabecular bone, preventing detrimental histomorphometric changes13,14. In the work by Sarter et al. (2017), mice infected with Heligmosomoides polygyrus bakeri (Hp) exhibited significantly fewer osteoclasts in vivo and a smaller area of bone covered by osteoclasts, suggesting that Hp products inhibit osteoclastogenesis and thus reduce bone resorption13. Similarly, Eissa et al. (2017) observed lower levels of IL-17 alongside increased IL-10 and Treg (Foxp3+) cells, both of which are known to inhibit osteoclast formation14,49. Taken together, these findings indicate that when parasites infect an inflamed host, they may modulate the immune response and alleviate chronic inflammation. This conclusion aligns with other studies showing that parasitic infections can dampen chronic systemic inflammation in conditions such as obesity or type II diabetes1,10.
The existing literature does not address how parasitic infections affect articular cartilage in healthy individuals during growth and development, making our research the first to describe these changes. We found that infection with Eimeria spp. significantly impacted articular cartilage histomorphometry, demonstrated by a decrease in the thickness of both the superficial and deep zones and a weaker proteoglycan reaction, particularly in the superficial zone and around nutrient channels. This results, suggesting that intestinal parasitic infection can adversely affect cartilage integrity.
Each zone of articular cartilage plays a distinct mechanical role. The superficial zone, both resists shear forces at the articulating surface and provides lubrication and tensile strength to protect deeper layers. The transitional zone, with its obliquely oriented collagen fibers, functions as a bridge distributing load between the surface and the deeper regions7,50,51. Finally, the deep zone, characterized by collagen fibers arranged perpendicular to the surface, bears the greatest compressive stresses. Eimeria infection led to significant thinning of both the superficial and deep zones, while the transitional zone remained unchanged. This pattern suggests that early-stage infection selectively compromises surface lubrication and compressive resistance but leaves interzone load transfer initially intact. Altered proteoglycan content in the may further impair the tissue’s capacity to retain water and withstand deformation50,51. Moreover, infection-driven disturbances in gastrointestinal homeostasis can disrupt fluid–electrolyte balance, potentially reducing cartilage hydration and matrix elasticity7,51. Together, these changes reduce the cartilage’s resilience and load-bearing function, even before transitional-zone structure is affected.
Studies that induced arthritis in experimental animals have reported results different from ours and from those of Lee et al. (2017) and Li et al. (2021)5,12. These experiments used varied animal models, distinct protocols for OA induction, and different parasite species13,14,52,53,54,55. Despite these differences in experimental design, most findings indicate that parasitic infections inhibit or attenuate arthritis development by reducing inflammation. However, not all studies have thoroughly investigated the mechanisms behind this protective effect on articular cartilage. For example, Osada et al. (2009) suggested that parasitic infection may suppress the synthesis of proinflammatory cytokines while increasing IL-10 production, an anti-inflammatory cytokine. He et al. (2011) reported similar observations54,55.
In contrast, our study infected healthy animals and measured IL-1, IL-6, IgY, and IgM levels in their serum56,57. Both IgM and IgY natural antibodies (NAb) remained significantly elevated in the Eimeria-infected birds throughout the study period. IgM, being the predominant NAb class in avian serum and notable for its polyreactivity, surges early after antigen encounter, providing a rapid, although broadly targeted, defense. IgY NAbs, analogous to mammalian IgG, develop more gradually and can serve as a long-term marker of antigen exposure and immunological memory58. The concomitant and sustained increase of IgM and IgY in our model therefore implies not only an acute polyreactive response but also the generation of more specific anti-Eimeria antibodies. Although we did not perform Eimeria-specific ELISAs in this study, these kinetic patterns align with classic humoral immunity - an early IgM peak followed by IgY persistence. Future work will include antigen-specific serology to dissect the relative contributions of natural versus adaptive antibody responses in coccidiosis-induced bone pathology.
Elevated immunoglobulin levels in the infected group indicate an active immune response, which could explain the increases in IL-1 and IL-659. The resulting inflammation appears to have contributed to the adverse skeletal changes noted in our experiments. Further supporting this conclusion, previous research shows that IL-1 stimulates osteoclastogenesis by increasing the expression of RANKL in osteoblasts41,60. In animals treated with IL-1β, calcium levels decreased while osteoclast counts rose. Conversely, therapy with a chimeric form of OPG reduced hypercalcemia and lowered osteoclast numbers41,60. This could also explain the significant OPG increase seen in our infected group. Notably, IL-1 is elevated in about 50% of osteoarthritis (OA) patients, and animal-model studies show that IL-1 family members in synovial fluid correlate with joint destruction severity61. Because IL-1 triggers IL-6 production, the rise in IL-1 may have led to the elevated IL-6 levels we observed, further stimulating osteoclast precursor formation and thereby intensifying bone resorption62. Finally, the immune response may have influenced hormonal regulation, which strongly affects skeletal health. In our study, infected animals exhibited a significant decline in IGF-1. This growth factor plays a crucial role in protein synthesis (including proteoglycans and collagen), supports chondrocyte differentiation and regeneration, and is vital for bone mineralization63.
Despite examining numerous bone and cartilage tissue properties, our work has a few limitations. First, our study design did not include a group treated for parasitic infection, which would have allowed us to determine whether the observed changes in bone and cartilage regress, remain stable, or worsen over time. Second, the present study is the absence of a post-infection recovery or therapeutic intervention group to determine whether the bone and cartilage alterations induced by Eimeria spp. are reversible, persistent, or progressive. Third, the study lacks the morphometry of the growth plate. Fourth, we did not assess osteocyte and chondrocyte activity by immunohistochemical methods, a significant limitation given the preliminary nature of our study. Nevertheless, the disruptions in skeletal homeostasis we observed underscore the need for further research.
Materials and methods
Animals
The experimental protocol was approved by the 2nd Local Ethical Committee for Animal Research in Krakow (Approval No. 1186/2015). The experiment was conducted in accordance with ARRIVE guidelines and all methods were performed in accordance with the relevant guidelines and regulations.
The experiment was conducted at the Experimental Station in Aleksandrowice, National Research Institute of Animal Production, Balice, Poland. One hundred male Ross308 broiler chickens (Gallus gallus domesticus), one day old, were used. The group sizes were chosen based on our previous research7. Animals were housed under conventional breeding conditions with constant ad libitum access to water and feed, formulated to meet age-specific nutritional requirements. Detailed feed composition is provided in Supplementary Table S1, nutrient content in Supplementary Table S2, and amino acid profile in Supplementary Table S3. Diets were coccidiostat-free and contained no anticoccidial additives to avoid interfering with the natural developmental cycle of the coccidia present in the standardized experimental inoculum. Upon arrival the chicks were randomly allotted to either a control or an infected group (10 pens per group, 5 birds per pen). This allocation was performed before any experimental intervention to ensure unbiased group composition. To minimize oocyst transfer risk, cages were separated by barriers made of PVC sheets. During the experiment, no differences were observed between animals in the amount of water or feed consumed. Animals in the infected group also showed no symptoms of diarrhea.
Infection protocol
On day 20 post-hatch, birds assigned to the infection group received an oral challenge consisting of 100 µL of Paracox-5 (Intervet Nederland B.V., Boxmeer, The Netherlands; Authorisation of use in EU No. REG NL 9687), i.e. 25 × the authorised 4 µL vaccine dose suspended in 240 µL of distilled water; an 340 µL of distilled water was administered to the control group. Based on the product specification, this volume delivered approximately 5 000–5 750 E. maxima CP, 12 500–15 000 E. acervulina, 25 000–32 500 E. mitis HP, 2 500–3 250 E. maxima MFP and 12 500–16 250 E. tenella HP live, sporulated oocysts per bird.
Collecting research material from animals
On day 42, a total of 20 animals (one per replicate cage, randomly selected) were euthanized by decapitation after electrical stunning using STZ6 apparatus (Koma Ltd., Wilkanowo, Poland). Blood and both tibiae were collected from each animal. Blood samples were centrifuged at 3000× g for 15 min to obtain serum, which was frozen at -60 °C for subsequent analyses. Tibiae were cleaned of soft tissue, weighed, measured, and stored frozen at -20 °C for further analyses. All samples were coded upon collection so that all subsequent measurements were per-formed in a blinded fashion.
Assessment of oocyst presence
Infection with Eimeria was confirmed by the McMaster method in a McMaster counting chamber to obtain oocysts per gram (OPG) of feces, analysed as log10(OPG + 1)64. Animals were confirmed oocyst-free prior to infection. Samples collected at 5, 6, 7, and 15 days post-infection (dpi), covering first and second shedding peak, confirmed the presence of Eimeria in experimental group (4.48 ± 0.31, 4.06 ± 0.44, 4.31 ± 0.16, and 3.38 ± 0.50 OPG, for 5, 6, 7, and 15 dpi, respectively). Post-mortem evaluation by an experienced veterinarian revealed macroscopic changes typical of Eimeria infection, such as gastrointestinal mucosal thickening and hyperemia, along with gas, blood, and reddish exudate in the small intestine.
Bone and articular cartilage analysis
Bone analyzes
DXA (Densitometry) analysis
Bone mineral content (BMC) and bone mineral density (BMD) were determined by dual-energy X-ray absorptiometry (DXA) using a Discovery W densitometer (Hologic Inc., Bedford, MA, USA). BMC and BMD values were calculated for the entire bone7.
Mechanical, Geometrical, and structural properties
Mechanical properties of bones were evaluated by a three-point bending test using a Zwick Z010 testing machine (Zwick GmbH & Company KG, Ulm, Germany), with data analyzed by Origin 2016 software (OriginLab, Northampton, MA, USA, available at: https://www.originlab.com/2016). Parameters measured included maximum elastic strength, elastic energy, ultimate strength, stiffness, work to fracture, and elastic energy65,66. Post-mechanical testing, geometric properties of tibial mid-diaphysis (including internal and external anteroposterior and transversal diameters) were measured using digital calipers. Given the elliptical cross-sectional shape, geometric parameters such as mean relative wall thickness (MRWT), cortical index, cortical cross-sectional area, and cross-sectional moment of inertia (CSMI) were determined65. Bone structural properties, including Young’s modulus of elasticity, yield strain, yield stress, ultimate strain, and ultimate stress, were calculated based on geometric and mechanical data.
Bone tissue density analysis
Bone tissue density (BTD), or volumetric density, was assessed on 5-cm-long mid-diaphysis segments using an AccuPyc 1330 helium pycnometer (Micromeritics, Inc., Norcross, GA, USA). Samples were defatted using a 2:1 chloroform: methanol mixture for 12 h, dried at 105 °C for 24 h, and cooled in vacuum desiccators prior to analysis7.
Analysis of bone mineral fraction
Following BTD assessment, bone samples were mineralized at 600 °C in a muffle furnace to determine ash content (percentage of dry, defatted bone mass). Ash samples were mineralized with HNO3 and HCl, and elemental analysis was conducted using ICP-OES (iCAP Series 6500, Thermo Scientific, Waltham, MA, USA), with TraceCERT multielement stock solution (Sigma‐Aldrich, St. Louis, MO, USA) as the reference standard. Mineral content was expressed in µg or mg per g dry, defatted bone mass67.
Bone histology
Samples for histological examination were obtained from tibial distal epiphyses (trabecular bone and cartilage) and mid-diaphysis cortical bone using a diamond bandsaw (MBS 240/E, Proxxon GmbH, Foehren, Germany). Specimens were decalcified in buffered 10% EDTA solution (pH 7.4) for 28 days. Next samples were dehydrated, embedded in paraffin, and cut into 4 μm sections using an HM360 microtome (Microm, Walldorf, Germany). Slides were stained with Safranin O or Picrosirius red (PSR), examined under standard or polarized light, respectively, using Olympus BX63 microscope (Olympus, Tokyo, Japan), and analyzed using the graphical analysis software ImageJ (ver. 1.54f, National Institutes of Health, Bethesda, MD, USA; available at: http://rsb.info.nih.gov/ij/index.html)66. PSR staining was used for assessment of trabecular bone histomorphometry, included bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp), and trabecular thickness (Tb.Th). Percentage of thin collagen content in compact and trabecular bone was evaluated by distinguishing thin (green) from thick (red) collagen in polarized-light observed PSR stained sections. The measurement method was performed in such a way as to maintain randomization and repeatability of analyses. Measurements were performed on three histological sections per birds, with three randomly selected areas of the compact and trabecular bone evaluated per section.
Analyze of articular cartilage
Cartilage collagen maturity was assessed using PSR-stained slides observed under polarized light similarly to bone analyses, while cartilage histomorphometry (zone-specific thickness) and proteoglycans distribution were assessed using Safranin O staining and Olympus cellSens software (v. 1.5, Olympus, Tokyo, Japan, available at: https://evidentscientific.com/en/products/software/cellsens/)68. The measurement method was performed in such a way as to maintain randomization and repeatability of analyses. Measurements were performed on three histological sections per birds, with three randomly selected areas of the articular cartilage evaluated per section.
Blood analysis
Serum osteocalcin (OC), osteoprotegerin (OPG), growth hormone (GH), insulin-like growth factor (IGF-1), tumor necrosis factor-alpha (TNF-α), interleukins (IL-1, IL-6), ceruloplasmin, immunoglobulins (IgY, IgM, IgI), and calcitriol were measured using commercial chicken-specific ELISA kits according to manufacturers’ instructions. Results were analyzed using a Benchmark Plus microplate reader (Bio-Rad Laboratories, Inc., Hercules, CA, USA). Serum Ca and P concentrations were determined photocolorimetrically using a Mindray BS-120 biochemical analyzer (BioMedical Electronics, Shenzhen, China). Ready-made biochemical reagent kits (Alpha Diagnostics, Warsaw, Poland) were. Each sample for each ELISA kits and biochemical analysis underwent three technical replicates.
Statistical analysis
Statistical analyses were performed with Statistica software (v. 13.0, IBCO Software Inc., Palo Alto, CA, USA, available at: https://www.statsoft.pl/zasoby/do-pobrania/sbkx4s9v9o/). Normality and variance homogeneity were assessed using Shapiro–Wilk and Levene tests, respectively. Differences were evaluated by Student’s t-test (with Welch’s correction for data showing unequal variance) or Mann–Whitney U test for non-parametric data. Significance was set at p < 0.05. Data are presented as means ± standard deviation.
Conclusions
In summary, this work represents the first comprehensive in vivo evaluation of how an enteric Eimeria spp. infection disrupts weight-bearing skeletal integrity in a bipedal model relevant to human health. We demonstrate for the first time that coccidial challenge impairs bone mechanical properties, collagen maturation in cortical and trabecular bone as well as articular cartilage, and we link these tissue changes to shifts in humoral immunity, proinflammatory cytokines, and bone-turnover regulators. Together, our findings indicate that isolated intestinal parasitism can precipitate a secondary, inflammation-mediated osteopathy in otherwise healthy, rapidly growing hosts, an effect with clear implications for developmental bone defects and increased risk of post-infectious skeletal disorders across the lifespan.
Data availability
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
References
Shea-Donohue, T., Qin, B. & Smith, A. Parasites, nutrition, immune responses and biology of metabolic tissues. Parasite Immunol 39, (2017).
Cama, V. A. & Mathison, B. A. Infections by intestinal coccidia and Giardia duodenalis. Clin. Lab. Med. 35, 423–444 (2015).
Burrell, A., Tomley, F. M. & Vaughan, S. Marugan-Hernandez, V. Life cycle stages, specific organelles and invasion mechanisms of Eimeria species. Parasitology 147, 263–278 (2020).
Tang, K. et al. Genetic similarities between Cyclospora cayetanensis and cecum-infecting avian Eimeria spp. In apicoplast and mitochondrial genomes. Parasit. Vectors. 8, 358 (2015).
Li, W. et al. Schistosome infection promotes osteoclast-mediated bone loss. PLoS Pathog. 17, e1009462 (2021).
Baxter, M. F. A. et al. Assessment of a nutritional rehabilitation model in two modern broilers and their jungle fowl ancestor: A model for better Understanding childhood undernutrition. Front. Nutr. 5, 18 (2018).
Tomczyk-Warunek, A. et al. Structural changes in trabecular bone, cortical bone and hyaline cartilage as well as disturbances in bone metabolism and mineralization in an animal model of secondary osteoporosis in Clostridium perfringens infection. J. Clin. Med. 11, 205 (2021).
Aguado, E., Pascaretti-Grizon, F., Goyenvalle, E., Audran, M. & Chappard, D. Bone mass and bone quality are altered by hypoactivity in the chicken. PLoS One. 10, e0116763 (2015).
Tompkins, Y. H. et al. Reduced bone formation and increased bone resorption drive bone loss in Eimeria infected broilers. Sci. Rep. 13, 616 (2023).
Rennie, C., Fernandez, R., Donnelly, S. & McGrath, K. C. The impact of helminth infection on the incidence of metabolic syndrome: A systematic review and Meta-Analysis. Front. Endocrinol. (Lausanne). 12, 728396 (2021).
Wong, S. K., Chin, K. Y., Suhaimi, F. H., Ahmad, F. & Ima-Nirwana, S. The relationship between metabolic syndrome and osteoporosis: A review. Nutrients 8, 347 (2016).
Lee, M. S. J. et al. Plasmodium products persist in the bone marrow and promote chronic bone loss. Sci. Immunol. 2, eaam8093 (2017).
Sarter, K., Kulagin, M., Schett, G., Harris, N. L. & Zaiss, M. M. Inflammatory arthritis and systemic bone loss are attenuated by Gastrointestinal helminth parasites. Autoimmunity 50, 151–157 (2017).
Eissa, M. M. et al. Anti-Arthritic activity of Schistosoma mansoni and Trichinella spiralis Derived-Antigens in adjuvant arthritis in rats: role of FOXP3 + Treg cells. PLoS One. 11, e0165916 (2016).
Tompkins, Y. H., Teng, P., Pazdro, R. & Kim, W. K. Long bone mineral Loss, bone microstructural changes and oxidative stress after Eimeria challenge in broilers. Front. Physiol. 13, 945740 (2022).
Akbari, M. et al. Eimeria challenge adversely affected long bone attributes linked to increased resorption in 14-day-old broiler chickens. Poult. Sci. 98, 1615–1621 (2019).
Fortuna, D. et al. SPIE,. Nd:YAG laser in experimentally induced chronic degenerative osteoarthritis in broiler chickens: pilot study. in Laser Florence 2001: A Window on the Laser Med. World 4903 77–84 (2002).
Sharma, M. K., Regmi, P., Applegate, T., Chai, L. & Kim, W. K. Osteoimmunology: A link between Gastrointestinal diseases and skeletal health in chickens. Animals 13, 1816 (2023).
López, J. M. Bone development and growth. Int. J. Mol. Sci. 25, 6767 (2024).
Oliveira, T. C., Gomes, M. S. & Gomes, A. C. The crossroads between infection and bone loss. Microorganisms 8, 1765 (2020).
Sözen, T., Özışık, L. & Başaran, N. Ç. An overview and management of osteoporosis. Eur. J. Rheumatol. 4, 46–56 (2017).
Klußmann, A. et al. Individual and occupational risk factors for knee osteoarthritis – Study protocol of a case control study. BMC Musculoskelet. Disord. 9, 26 (2008).
Sakka, S. D. Osteoporosis in children and young adults. Best Pract. Res. Clin. Rheumatol. 36, 101776 (2022).
Arvonen, M. et al. Gut microbiota-host interactions and juvenile idiopathic arthritis. Pediatr. Rheumatol. 14, 44 (2016).
De Roover, A., Escribano-Núñez, A., Monteagudo, S. & Lories, R. Fundamentals of osteoarthritis: inflammatory mediators in osteoarthritis. Osteoarthr. Cartil. 31, 1303–1311 (2023).
Fitzpatrick, L. A. Secondary causes of osteoporosis. Mayo. Clin. Proc. 77, 453–468 (2002).
Halliez, M. C. M. & Buret, A. G. Gastrointestinal parasites and the neural control of gut functions. Front. Cell. Neurosci. 9, 452 (2015).
Huang, Z. et al. Faecal microbiota transplantation from metabolically compromised human donors accelerates osteoarthritis in mice. Ann. Rheum. Dis. 79, 646–656 (2020).
Song, X. et al. Impact of Schistosoma Japonicum infection on collagen-induced arthritis in DBA/1 mice: a murine model of human rheumatoid arthritis. PLoS One. 6, e23453 (2011).
Zhu, K. et al. Toxoplasma gondii infection as a risk factor for osteoporosis: a case–control study. Parasit. Vectors. 15, 151 (2022).
Liu, F. et al. Schistosoma Japonicum Cystatin attenuates murine collagen-induced arthritis. Parasitol. Res. 115, 3795–3806 (2016).
Lu, C., Yan, Y., Jian, F. & Ning, C. Coccidia-Microbiota interactions and their effects on the host. Front. Cell. Infect. Microbiol. 11, 751481 (2021).
Kourkoumelis, N., Balatsoukas, I. & Tzaphlidou, M. Ca/P concentration ratio at different sites of normal and osteoporotic rabbit bones evaluated by Auger and energy dispersive X-ray spectroscopy. J. Biol. Phys. 38, 279–291 (2012).
Baslé, M. F. et al. Concentration of bone elements in osteoporosis. J. Bone Min. Res. 5, 41–47 (1990).
Liu, G., Sharma, M. K., Tompkins, Y. H., Teng, P. Y. & Kim, W. K. Different methionine to cysteine supplementation ratios altered bone quality of broilers with or without Eimeria challenge assessed by dual energy X-ray absorptiometry and microtomography. Poult. Sci. 103, 103580 (2024).
Ciosek, Ż., Kot, K., Kosik-Bogacka, D., Łanocha-Arendarczyk, N. & Rotter, I. The effects of Calcium, Magnesium, Phosphorus, Fluoride, and lead on bone tissue. Biomolecules 11, 506 (2021).
Saito, M. et al. Changes in the contents of enzymatic immature, mature, and non-enzymatic senescent cross-links of collagen after once-weekly treatment with human parathyroid hormone (1–34) for 18 months contribute to improvement of bone strength in ovariectomized monkeys. Osteoporos. Int. 22, 2373–2383 (2011).
Viguet-Carrin, S., Garnero, P. & Delmas, P. D. The role of collagen in bone strength. Osteoporos. Int. 17, 319–336 (2006).
Schurman, C. A. et al. Aging impairs the osteocytic regulation of collagen integrity and bone quality. Bone Res. 12, 13 (2024).
Takeuchi, T., Yoshida, H. & Tanaka, S. Role of interleukin-6 in bone destruction and bone repair in rheumatoid arthritis. Autoimmun. Rev. 20, 102884 (2021).
Tseng, H. W., Samuel, S. G., Schroder, K., Lévesque, J. P. & Alexander, K. A. Inflammasomes and the IL-1 family in bone homeostasis and disease. Curr. Osteoporos. Rep. 20, 170–185 (2022).
Zhang, Z., Tang, H., Du, T. & Yang, D. The impact of copper on bone metabolism. J. Orthop. Translat. 47, 125–131 (2024).
Han, J., Luo, J., Wang, C., Kapilevich, L. & Zhang, X. A. Roles and mechanisms of copper homeostasis and Cuproptosis in osteoarticular diseases. Biomed. Pharmacother. 174, 116570 (2024).
Zofková, I., Nemcikova, P. & Matucha, P. Trace elements and bone health. Clin. Chem. Lab. Med. 51, 1555–1561 (2013).
Dermience, M., Lognay, G., Mathieu, F. & Goyens, P. Effects of Thirty elements on bone metabolism. J. Trace Elem. Med. Biol. 32, 86–106 (2015).
Li, G., Cheng, T. & Yu, X. The impact of trace elements on osteoarthritis. Front. Med. (Lausanne). 8, 771297 (2021).
Yuan, X. et al. Effect of copper on levels of collagen and alkaline phosphatase activity from chondrocytes in newborn piglets in vitro. Biol. Trace Elem. Res. 144, 597–605 (2011).
Wang, H. et al. The endocrine role of bone: novel functions of bone-derived cytokines. Biochem. Pharmacol. 183, 114308 (2021).
Moudgil, K. D., Kim, P. & Brahn, E. Advances in rheumatoid arthritis animal models. Curr. Rheumatol. Rep. 13, 456–463 (2011).
Poole, A. R. et al. Composition and structure of articular cartilage: a template for tissue repair. Clin. Ortho P Relat. Res. S26-33 https://doi.org/10.1097/00003086-200110001-00004 (2001).
Sophia Fox, A. J., Bedi, A. & Rodeo, S. A. The basic science of articular cartilage: structure, composition, and function. Sports Health. 1, 461–468 (2009).
Matisz, C. E., McDougall, J. J., Sharkey, K. A. & McKay, D. M. Helminth parasites and the modulation of joint inflammation. J. Parasitol. Res. 942616 (2011). (2011).
Salinas-Carmona, M. C. et al. Spontaneous arthritis in MRL/lpr mice is aggravated by Staphylococcus aureus and ameliorated by Nippostrongylus Brasiliensis infections. Autoimmunity 42, 25–32 (2009).
Osada, Y., Shimizu, S., Kumagai, T., Yamada, S. & Kanazawa, T. Schistosoma mansoni infection reduces severity of collagen-induced arthritis via down-regulation of pro-inflammatory mediators. Int. J. Parasitol. 39, 457–464 (2009).
He, Y. et al. The inhibitory effect against collagen-induced arthritis by Schistosoma Japonicum infection is infection stage-dependent. BMC Immunol. 11, 28 (2010).
Thirumalai, D. et al. Chicken egg yolk antibody (IgY) as diagnostics and therapeutics in parasitic infections - A review. Int. J. Biol. Macromol. 136, 755–763 (2019).
Furst, D. E. Serum Immunoglobulins and risk of infection: how low can you go? Semin Arthritis Rheum. 39, 18–29 (2009).
Sarrigeorgiou, I. et al. Levels of Circulating IgM and IgY natural antibodies in broiler chicks: association with genotype and farming systems. Biology (Basel). 12, 304 (2023).
Arend, W. P. & Leung, D. Y. IgG induction of IL-1 receptor antagonist production by human monocytes. Immunol. Rev. 139, 71–78 (1994).
Morony, S. et al. A chimeric form of osteoprotegerin inhibits hypercalcemia and bone resorption induced by IL-1beta, TNF-alpha, PTH, PTHrP, and 1, 25(OH)2D3. J. Bone Min. Res. 14, 1478–1485 (1999).
van Dalen, S. C. M. et al. Interleukin-1 is not involved in synovial inflammation and cartilage destruction in collagenase-induced osteoarthritis. Osteoarthr. Cartil. 25, 385–396 (2017).
Harmer, D., Falank, C. & Reagan, M. R. Interleukin-6 interweaves the bone marrow Microenvironment, bone Loss, and multiple myeloma. Front. Endocrinol. (Lausanne). 9, 788 (2018).
Wen, C. et al. Insulin-like growth factor-1 in articular cartilage repair for osteoarthritis treatment. Arthritis Res. Ther. 23, 277 (2021).
Arczewska-Włosek, A. et al. Effects of Anticoccidial Vaccination and Taraxacum officinale Extract on the Growth Performance, Biochemical Parameters, Immunity, and Intestinal Morphology of Eimeria-Challenged Chickens. Life (Basel) 13, (2023). (1927).
Muszyński, S. et al. Effect of Caponization on performance and quality characteristics of long bones in Polbar chickens. Poult. Sci. 96, 491–500 (2017).
Tomaszewska, E. et al. The effect of Tannic acid on bone mechanical and geometric properties, bone density, and trabecular histomorphometry as well as the morphology of articular and growth cartilages in rats co-exposed to cadmium and lead is dose dependent. Toxicol. Ind. Health. 33, 855–866 (2017).
Muszyński, S., Tomaszewska, E., Kwiecień, M., Dobrowolski, P. & Tomczyk-Warunek, A. Subsequent somatic axis and bone tissue metabolism responses to a low-zinc diet with or without phytase inclusion in broiler chickens. PLoS One. 13, e0191964 (2018).
Rudyk, H. et al. Bone homeostasis in experimental fumonisins intoxication of rats. Ann. Anim. Sci. 19, 403–419 (2019).
Funding
This experiment was supported by the National Centre for Research and Development in Poland and conducted within the Biostrateg grant ‘GUTFEED-innovative nutrition in sustainable poultry production’, grant number: BIO-STRATEG1/267659/7/NCBR/2015.
Author information
Authors and Affiliations
Contributions
Methodology, Conceptualization, Original Paper Writing: A.T.-W; P.D.; A.A.-W; S.S. and D.J. Resources, Investigation: A.T.-W and E.T. Paper Editing and Final Review: S.M. and E.T. Data Acquisition and Formal Analysis. S.M. and A.T.W.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Tomczyk-Warunek, A., Muszyński, S., Tomaszewska, E. et al. The influence of parasitic infection (Eimeria spp.) on bone and cartilage tissue in an animal model. Sci Rep 15, 38634 (2025). https://doi.org/10.1038/s41598-025-22579-x
Received:
Accepted:
Published:
Version of record:
DOI: https://doi.org/10.1038/s41598-025-22579-x
