Innate Immune Response Mechanisms in Vertebrate Systems

The innate immune response constitutes the first line of defence in vertebrate organisms, relying on germline-encoded receptors to detect conserved microbial patterns and danger signals. Recognition of pathogens is mediated by families of pattern-recognition receptors, including Toll-like receptors, NOD-like receptors and C-type lectins, which trigger intracellular signalling cascades such as NF-κB and MAPK pathways. These pathways culminate in the production of inflammatory cytokines, chemokines and antimicrobial peptides, as well as the activation of programmed cell-death programmes. Among these, pyroptosis—a lytic form of cell death executed by gasdermin pores—serves to eliminate infected cells and amplify local inflammation. Inflammasomes, multiprotein platforms assembled by NOD-like or AIM2-like receptors, activate inflammatory caspases that process interleukin-1β and interleukin-18 and cleave gasdermin D or E to induce pyroptosis. Neutrophils and macrophages coordinate bacterial clearance via reactive oxygen species, phagocytosis and cytokine release, while non-immune cells can contribute to barrier integrity and early warning. Comparative studies across fish, amphibians, birds and mammals have revealed both conserved modules and lineage-specific adaptations, highlighting the evolutionary flexibility of innate defences. Practical applications of this research include vaccine adjuvant design, therapeutic modulation of inflammasomes in autoinflammatory diseases and engineered cell therapies that harness pattern-recognition pathways to combat infection and cancer.

Research from Nature Portfolio

Recent work has demonstrated that guanylate-binding proteins act as inflammasome adaptors in neutrophils, driving prostaglandin D₂ biosynthesis and efficient bacterial clearance. This study revealed that transient inflammasome activation in zebrafish neutrophils promotes chemokine and leukotriene production, recruiting additional phagocytes to the infection site and illustrating a conserved mechanism of cytosolic pathogen sensing and lipid mediator synthesis.

Another investigation identified a noncanonical inflammasome sensor in teleost fish that directly binds cytosolic lipopolysaccharide via a pyrin-domain–mediated oligomerisation. Activation of this pathway led to pyroptotic death and interleukin-1β release in zebrafish gut tissues, revealing an evolutionary link between mammalian caspase-11-dependent sensing and the death-domain superfamily in lower vertebrates.

Innate Immune Response Mechanisms in Vertebrate Systems publication trend

The graph below shows the total number of articles in innate immune response mechanisms in vertebrate systems across all publications each year (not limited to Nature Index journals).

Technical terms

Inflammasome: A multiprotein complex that activates inflammatory caspases to process cytokines and induce pyroptosis in response to intracellular danger signals.

Pyroptosis: A form of programmed cell death characterised by gasdermin-mediated membrane pore formation, cell swelling and release of proinflammatory contents.

Pattern-recognition receptor: A germline-encoded sensor that detects conserved microbial or damage-associated molecular patterns to initiate innate immune signalling.

Gasdermin: A family of pore-forming proteins cleaved by inflammatory or apoptotic caspases to execute pyroptotic cell death.

Adaptor protein (ASC): An apoptosis-associated speck-like protein containing a CARD domain that bridges sensor proteins to inflammatory caspases within the inflammasome.

References

1. Neutrophils mediate Salmonella Typhimurium clearance through the GBP4 inflammasome-dependent production of prostaglandins. Nature Communications (2016).
2. Sensing of cytosolic LPS through caspy2 pyrin domain mediates noncanonical inflammasome activation in zebrafish. Nature Communications (2018).
3. CcGSDMEa functions the pore-formation in cytomembrane and the regulation on the secretion of IL-lβ in common carp (Cyprinus carpio haematopterus). Frontiers in Immunology (2023).
4. Pufferfish gasdermin Ea is a significant player in the defense against bacterial pathogens. Marine Life Science & Technology (2024).
5. Molecular Characterization, Expression, and Regulatory Signal Pathway Analysis of Inflammasome Component Apoptosis-Associated Speck-like Protein Containing a CARD Domain (ASC) in Large Yellow Croaker (Larimichthys crocea). International Journal of Molecular Sciences (2023).