Diverse Functions of Pulmonary Collectins in Host Defense of the Lung

Figure 3

Pulmonary collectins modulate inflammation via TLRs. Association of SP-A with TLR2 or TLR4/MD-2 complex results in the downregulation of inflammatory responses by inhibiting the recognition of non-SP-A ligands including smooth LPS, peptidoglycan, and zymosan via TLRs. In contrast, SP-A dose not inhibit secretion of proinflammatory cytokines induced by rough LPS, which is an SP-A ligand. Interaction of SP-D with TLR4/MD-2 complex inhibits proinflammatory cytokine production induced by both smooth and rough LPS.