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WISP1-v3 integrin signaling positively regulates TLR-triggered inflammation response in sepsis induced lung injury

Chen, Z;Ding, X;Jin, S;Pitt, B;Zhang, L;Billiar, T;Li, Q;

We recently noted that the matricellular protein WISP1 contributes to sepsis induced acute lung injury (ALI) via integrin 6. In the current study, we pursued further aspects of WISP1 modulation of TLR signaling in lungs of mice after sepsis and TLR4 mediated release of TNF- in macrophages. After confirming that TLR4 and CD14 are critical in transducing sepsis mediated ALI, we now demonstrate that intrapulmonary v3 is increased by polymicrobrial sepsis in a TLR4, CD14 dependent fashion. Comparison of cultured macrophages revealed that WISP1 increased release of TNF- from RAW264.7 cells with baseline expression of v3, but primary cultures of peritoneal macrophages (PM) required activation of TLR4 to induce de novo synthesis of v3 enabling WISP1 to stimulate release of TNF-. The specific requirement for 3 integrin was apparent when the effect of WISP1 was lost in PM isolated from 3(-/-) mice. WISP1 enhanced TLR4 mediated ERK signaling and U0126 (an ERK inhibitor) blocked LPS induced 3 integrin expression and WISP1 enhanced TNF- release. Collectively these data suggest that WISP1-v3 integrin signaling is involved in TLR4 pathways in macrophages and may be an important contributor to TLR4/CD14 mediated inflammation in sepsis induced lung injury.