Humanized anti-TLR4 monoclonal antibody ameliorates lipopolysaccharide-related acute kidney injury by inhibiting TLR4/NF-κB signaling

A humanized anti-Toll-like receptor 4 (TLR4) monoclonal antibody (mAb) was previously produced using phage antibody library technology, and it was found that the mAb could effectively ameliorate lipopolysaccharide (LPS)-induced damage in macrophages. The present study investigated the protective effects exerted by the humanized anti-TLR4 mAb against LPS-induced acute kidney injury (AKI), as well as the underlying mechanisms. Female C57BL/6 mice were randomly divided into four groups (n=8 per group): i) Control; ii) LPS; iii) LPS + humanized anti-TLR4 mAb (1 mu g/g); and iv) LPS + humanized anti-TLR4 mAb (10 mu g/g). Serum creatinine, blood urea nitrogen, IL-6, TNF alpha and IL-1 beta levels were then examined, followed by renal pathology assessment, immunohistochemical staining, reverse transcription-quantitative PCR and western blotting to assess apoptosis/survival/inflammation-related molecules and kidney injury molecule (KIM)-1. The humanized anti-TLR4 mAb successfully ameliorated LPS-induced AKI and renal pathological damage. The humanized anti-TLR4 mAb also dose-dependently suppressed LPS-induced elevations in serum IL-6, TNF alpha and IL-1 beta, and decreased the renal expression levels of myeloid differentiation primary response 88 (MyD88), IKK alpha/beta, I kappa B, p65 and KIM-1. Compared with the LPS group, renal Bax and KIM-1 expression levels were significantly downregulated, and Bcl-2 expression was notably upregulated by the humanized anti-TLR4 mAb. Moreover, the humanized anti-TLR4 mAb also significantly decreased the protein expression levels of MyD88, phosphorylated (p)-IKK alpha/beta, p-I kappa B and p-p65 in the renal tissues compared with the LPS group. Therefore, the present study indicated that the anti-inflammatory effects of the humanized anti-TLR4 mAb against LPS-related AKI in mice were mediated via inhibition of the TLR4/NF-kappa B signaling pathway.