Acute kidney injury: what part do toll-like receptors play?

Abstract

Patricia G Vallés,1,2 Andrea Gil Lorenzo,2 Victoria Bocanegra,2 Roberto Vallés3 1Área de Fisiopatología, Departamento de Patología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina; 2National Council of Scientific and Technical Research of Argentina, Buenos Aires, Argentina; 3Instituto de Inmunología Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina Abstract: The innate immune system plays an important role as a first response to tissue injury. This first response is carried out via germline-encoded receptors. Toll-like receptors (TLRs) are the first identified and best studied family of pattern recognition receptors. TLRs are expressed on a variety of cell types, including epithelial cells, endothelia, dendritic cells, monocytes/macrophages, and B- and T-cells. TLRs initiate innate immune responses and concurrently shape the subsequent adaptive immune response. They are sensors of both pathogens, through the exogenous pathogen-associated molecular patterns (PAMPs), and tissue injury, through the endogenous danger-associated molecular patterns (DAMPs). TLR signaling is critical in defending against invading microorganisms; however, sustained receptor activation is also implicated in the pathogenesis of inflammatory diseases. Ischemic kidney injury involves early TLR-driven immunopathology, and the resolution of inflammation is needed for rapid regeneration of injured tubule cells. Notably, the activation of TLRs also has been implicated in epithelial repair. This review focuses on the role of TLRs and their endogenous ligands within the inflammatory response of acute kidney injury. Keywords: toll-like receptors, pathogen-associated molecular patterns (PAMPs), danger-associated molecular patterns (DAMPs), ischemic kidney injury