TLR4 and pulmonary fibrosis: Thus, moderate-intensity aerobic exercise (60 min/day, five times/week for 4 weeks) attenuates silica-induced lung fibrosis by inhibiting the TLR4-TNF-α, SRB-NLPR3, TGF-β1, and IL-17A/CXCL5/CXCR2 signaling pathways.