CFTR regulates B cell activation and lymphoid follicle development

Area of Science:

• Immunology
• Genetics
• Pulmonology

Background:

• Cystic fibrosis (CF) results from CF transmembrane conductance regulator (CFTR) gene mutations, leading to lung inflammation and dysfunction.
• Patients with CF exhibit elevated lung lymphoid follicles (LFs) and B cell-activating factor (BAFF), crucial for B cell regulation.
• The precise role of CFTR in B cell activation and CF pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the direct role of CFTR in B cell activation, proliferation, and lymphoid follicle development in cystic fibrosis.
• To examine B cell and lymphoid follicle characteristics in CF patients and CFTR-deficient mice.

Main Methods:

• Immunostaining was used to quantify lymphoid follicles (LFs), B cells (BAFF+, TLR4+, Ki67+, CXCR4+), and immunoglobulin G+ B cells in lung tissues from CF subjects and CFTR-deficient mice.
• Flow cytometry assessed B cell activation markers and MHC class II expression in lung and splenocytes.
• In vitro assays measured inflammatory cytokine (IL-6) production by B cells stimulated with lipopolysaccharide (LPS).

Main Results:

• CF subjects showed significantly increased well-formed lung LFs, B cell activation, and proliferation (elevated BAFF, TLR4, Ki67).
• CFTR-deficient mice exhibited more lung LFs and increased BAFF+, CXCR4+ B cells compared to controls.
• B cells from CFTR-deficient mice displayed higher MHC class II expression and produced more IL-6 upon LPS stimulation.

Conclusions:

• CFTR plays a direct role in regulating B cell activation, proliferation, and inflammatory cytokine production.
• These B cell dysfunctions contribute to the development of lung lymphoid follicles in cystic fibrosis.
• Targeting CFTR-mediated B cell pathways may offer new therapeutic strategies for CF lung disease.