Chitin-Mediated Modulation of Innate Immune Responses

Chitin, a β-(1→4)-linked polymer of N-acetyl-d-glucosamine, is a ubiquitous structural polysaccharide in fungal cell walls, arthropod exoskeletons and certain marine organisms. Beyond its structural role, chitin serves as a pathogen-associated molecular pattern that can engage multiple innate immune receptors and shape the balance between pro-inflammatory and regulatory outcomes. Recognition by pattern recognition receptors (PRRs) such as Toll-like receptors, C-type lectins and intracellular sensors leads to activation of signalling cascades that culminate in cytokine and chemokine release, recruitment of neutrophils, eosinophils and macrophages, and priming of adaptive immunity. The size, degree of acetylation and physical presentation of chitin influence receptor engagement and downstream responses: large particles tend to provoke pro-inflammatory cascades, whereas smaller fragments may induce anti-inflammatory mediators such as interleukin-10. Chitin also acts as a potent adjuvant for type 2 immunity, driving production of epithelial alarmins (IL-33, thymic stromal lymphopoietin) and promoting T helper 2 cell and group 2 innate lymphoid cell activation. This duality underpins chitin’s global significance in allergy, asthma and host defence, and has prompted exploration of chitin-based materials as immunomodulatory therapeutics and vaccine adjuvants.

Research from Nature Portfolio

Recent studies have elucidated how epithelial-derived alarmins mediate chitin-driven type 2 inflammation. A 2021 investigation demonstrated that inhaled chitin beads trigger production of IL-33 and thymic stromal lymphopoietin by alveolar and bronchial epithelial cells, selectively activating resident lung Th2 cells and group 2 innate lymphoid cells to produce IL-5 and drive airway eosinophilia. Complementarily, an earlier work revealed that chitin co-delivered with antigen enhances IL-33–dependent IL-1β release by dendritic cells, acting as an adjuvant that amplifies antigen-specific Th2-mediated airway inflammation. Together, these studies define a mechanism whereby chitin engages epithelial and myeloid pathways to exacerbate allergic airway disease and offer targets for therapeutic intervention.

Chitin-Mediated Modulation of Innate Immune Responses publication trend

The graph below shows the total number of articles in chitin-mediated modulation of innate immune responses across all publications each year (not limited to Nature Index journals).

Technical terms

Chitin: Insoluble polysaccharide of β-(1→4)-linked N-acetyl-d-glucosamine units, serving as a pathogen-associated molecular pattern.

Pattern Recognition Receptor (PRR): Innate immune receptor that detects conserved microbial structures and initiates immune signalling.

Toll-Like Receptor 2 (TLR2): Cell-surface PRR that recognises lipoproteins and acetylated carbohydrates, including chitin derivatives.

C-Type Lectin Receptor (e.g. Dectin-2): Carbohydrate-binding receptor on myeloid cells that senses fungal polysaccharides and mediates phagocytosis and cytokine production.

IL-33 and Thymic Stromal Lymphopoietin (TSLP): Epithelial-derived cytokines (“alarmins”) that prime type 2 immune responses and eosinophilic inflammation.

References

1. Direct activation of Toll-like receptor 2 signaling stimulated by contact with the interfacial structures of chitin nanofibers. International Journal of Biological Macromolecules (2024).
2. Fungal chitin-binding glycoprotein induces Dectin-2-mediated allergic airway inflammation synergistically with chitin. PLOS Pathogens (2024).
3. Interleukin-33 and thymic stromal lymphopoietin, but not interleukin-25, are crucial for development of airway eosinophilia induced by chitin. Scientific Reports (2021).
4. Chitin promotes antigen-specific Th2 cell-mediated murine asthma through induction of IL-33-mediated IL-1β production by DCs. Scientific Reports (2018).
5. The Effect of Chitin Size, Shape, Source and Purification Method on Immune Recognition. Molecules (2014).
6. Fungal Chitin Dampens Inflammation through IL-10 Induction Mediated by NOD2 and TLR9 Activation. PLOS Pathogens (2014).