TLR4 and pulmonary fibrosis: Evidence has indicated that the development of pulmonary fibrosis is linked to the cd19 signaling pathway, which modulates B cell infiltration into lung tissue.[23] Through signaling via Toll-like receptor 4, cd19 has been shown to regulate the production of fibrotic cytokines by B cells and to control fibrotic responses in both skin and lung tissues.[24] These findings underscore the significance of cd19 in regulating B cell function and immune responses while mitigating inflammation and fibrosis in IPF.