Abstract
Abstract Viral infections are often accompanied by pulmonary microvascular leakage and vascular endothelial dysfunction via mechanisms that are not completely defined. Here, we investigated the effect of the Toll-like receptor 3 ligand Poly (I:C), a synthetic analog of viral double-stranded RNA commonly used to simulate viral infections, on the barrier function and tight junction integrity of primary human lung microvascular cells. Poly (I:C) produced a dose- and time-dependent increase in endothelial monolayer permeability accompanied by a corresponding decrease in the expression of claudin-5, a transmembrane tight junction protein. Immunofluorescence experiments revealed disappearance of membrane-associated claudin-5 and co-localization of internalized claudin-5 with lysosomal-associated membrane protein 1 (LAMP-1), a marker of lysosomes, suggesting enhanced lysosomal degradation of claudin-5. Poly (I:C) also induced a dose- and time-dependent cleavage of TLR3 and TRIF as well as activation of NF-kB and IRF3, but not IRF7 (MyD88-dependent pathway), consistent with the direct stimulation of the TLR3 signaling. Pronounced inflammatory response with the release of IL-6, IL-8, MCP-1 and RANTES and a hallmark TLR3-mediated type 1 IFN production (IFNbeta) was also observed. Together, these findings provide new insight on how virally-activated signaling pathways may disrupt vascular endothelial function and contribute to vascular leakage pathologies.
Published Version
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