Inflammation and Bone Health in Postmenopausal Women

Postmenopausal women undergo hormonal changes characterised by oestrogen deficiency that disrupt bone homeostasis and promote a low-grade inflammatory state. This so-called inflamm-aging involves elevated levels of proinflammatory cytokines—such as interleukin-6, tumour necrosis factor-α and interleukin-1β—that enhance osteoclast differentiation and activity while impairing osteoblast function. The resulting imbalance accelerates bone resorption, reduces bone mineral density and increases fracture risk. Immune cell populations, notably T lymphocytes and monocytes, are now recognised as active participants in skeletal remodelling. Oestrogen deficiency alters the profile of T helper subsets, favouring the expansion of inflammatory Th17 cells and elevated receptor activator of nuclear factor-κB ligand expression, further tipping the balance towards bone loss. Blood-based inflammatory markers, including high-sensitivity C-reactive protein and composite indices such as the systemic immune-inflammation index, have emerged as accessible predictors of low bone density and osteoporotic risk. Integrating mechanistic insights with clinical biomarkers offers new avenues for risk stratification and targeted interventions, ranging from anti-cytokine therapies to lifestyle strategies that mitigate chronic inflammation and preserve skeletal health.

Research from Nature Portfolio

Using genetic instruments to probe causality, recent Mendelian randomisation work has examined whether systemic inflammation directly influences bone mineral density. By leveraging genome-wide associations for high-sensitivity C-reactive protein and relating these to bone density measures at multiple skeletal sites, this analysis found no evidence that elevated C-reactive protein per se causally reduces bone mineral density. These findings suggest that while inflammation biomarkers correlate with low BMD in observational studies, they may reflect downstream effects of bone loss or shared determinants rather than direct drivers of osteoporosis.

Inflammation and Bone Health in Postmenopausal Women publication trend

The graph below shows the total number of articles in inflammation and bone health in postmenopausal women across all publications each year (not limited to Nature Index journals).

Technical terms

Bone mineral density (BMD): A quantitative measurement of mineral content in bone, typically assessed by dual-energy X-ray absorptiometry as an indicator of bone strength and fracture risk.

High-sensitivity C-reactive protein (hsCRP): A sensitive assay for C-reactive protein, an acute-phase protein whose blood concentration rises in response to systemic inflammation.

Systemic immune-inflammation index (SII): A composite inflammatory marker calculated as (platelet count × neutrophil count) ÷ lymphocyte count, reflecting overall immune and inflammatory status.

Monocyte-to-lymphocyte ratio (MLR): The ratio of monocyte count to lymphocyte count in peripheral blood, used as an indicator of immune-inflammatory balance.

Cytokines: Small protein mediators secreted by immune cells (e.g. interleukin-6, tumour necrosis factor-α, interleukin-1β) that regulate inflammation and bone remodelling.

Osteoclast: A type of specialised cell that resorbs bone tissue during remodelling, derived from monocyte-macrophage lineage.

Osteoblast: A bone-forming cell responsible for synthesising and mineralising new bone matrix.

Th17 cells: A subset of proinflammatory CD4+ T helper lymphocytes characterised by production of interleukin-17, implicated in driving osteoclast activation under oestrogen deficiency.

References

1. Osteoporosis, inflammation and ageing. Immunity & Ageing (2005).
2. Inflammation and bone mineral density: A Mendelian randomization study. Scientific Reports (2017).
3. Systemic immune-inflammation index and bone mineral density in postmenopausal women: A cross-sectional study of the national health and nutrition examination survey (NHANES) 2007-2018. Frontiers in Immunology (2022).
4. The relationship between the monocyte-to-lymphocyte ratio and osteoporosis in postmenopausal females with T2DM: A retrospective study in Chinese population. Frontiers in Endocrinology (2023).
5. T-Cell Mediated Inflammation in Postmenopausal Osteoporosis. Frontiers in Immunology (2021).
6. Estrogen Deficiency Induces the Differentiation of IL-17 Secreting Th17 Cells: A New Candidate in the Pathogenesis of Osteoporosis. PLOS ONE (2012).