Type I interferon induces CXCL13 to support ectopic germinal center formation

Area of Science:

• Immunology
• Cell Biology
• Virology

Background:

• Ectopic lymphoid structures (ELS) are observed in various inflammatory conditions, including infections, autoimmune diseases, and cancer.
• Pulmonary ELS induced by influenza A virus infection can enhance host defense through cross-strain protective antibody responses.
• The mechanisms by which inflammation drives the conversion of peripheral tissues into secondary lymphoid organ-like structures remain largely unknown.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying the formation of ectopic lymphoid structures in the lung following viral infection.
• To identify key cellular and molecular players involved in inflammation-induced tissue remodeling that supports lymphoid neogenesis.

Main Methods:

• Investigated the role of type I interferon (IFN) in inducing chemokine expression in lung fibroblasts after viral infection.
• Utilized techniques to assess B cell recruitment and ectopic germinal center formation in response to induced CXCL13 expression.
• Examined the dependence of B cell recruitment on the CXCR5 receptor.

Main Results:

• Type I IFN, produced during viral infection, was identified as a novel inducer of CXCL13 expression in a specific subset of lung fibroblasts.
• CXCL13 expression by these fibroblasts promoted CXCR5-dependent recruitment of B cells.
• This process initiated the formation of ectopic germinal centers within the lung tissue.

Conclusions:

• Type I interferon is a critical mediator that converts non-lymphoid lung tissue into a site permissive for tertiary lymphoid structure formation.
• The induction of CXCL13 by type I IFN in lung fibroblasts is a key step in initiating ectopic germinal center formation during viral infections.
• Understanding these mechanisms offers insights into immune responses in non-lymphoid tissues and potential therapeutic targets.