TLR4 Knockout Attenuates BDL-induced Liver Cholestatic Injury through Amino Acid and Choline Metabolic Pathways

Unveiling the hub genes associated with aflatoxin B1-induced hepatotoxicity in chicken

Aflatoxin B1 (AFB1), a ubiquitous and toxic mycotoxin in human food and animal feedstuff, can impair the function and health of some organs, especially the liver. However, the knowledge about the potential mechanisms of AFB1-induced hepatotoxicity in chickens is limited. Therefore, we analyzed the gene expression data of chicken embryo primary hepatocytes (CEPHs) treated with and without AFB1 at the dose of 0.1 μg/mL which were cultured at 37 °C in Medium 199 (Life Technologies, Shanghai, China) with 5.0% CO2 for 48 h. Totally 1,711 differentially expressed genes (DEGs) were identified, in which 1,170 and 541 genes were up- and down-regulated in AFB1-administrated CEPHs compared to the control, respectively. Biological process analysis suggested that these DEGs might take part in angiogenesis, cell adhesion, immune response, cell differentiation, inflammatory response, cell migration regulation, and blood coagulation. Signaling pathways analysis revealed that these DEGs were mainly linked to metabolic pathways, MAPK, TLR2, and actin cytoskeleton regulation pathways. Moreover, the hub genes, including GYS2, NR1H4, ALDH8A1, and ANGPTL3, might participate in AFB1-induced hepatotoxicity. Taken together, our study offers a new insight into the mechanisms of the AFB1-induced hepatotoxicity.

Role of Toll-like receptor 4 in intravascular hemolysis-mediated injury

Massive intravascular hemolysis is a common characteristic of several pathologies. It is associated with the release of large quantities of heme into the circulation, promoting injury in vulnerable organs, mainly kidney, liver, and spleen. Heme activates Toll-like receptor 4 (TLR4), a key regulator of the inflammatory response; however, the role of TLR4 in hemolysis and whether inhibition of this receptor may protect from heme-mediated injury are unknown. We induced intravascular hemolysis by injection of phenylhydrazine in wildtype and Tlr4-knockout mice. In this model, we analyzed physiological parameters, histological damage, inflammation and cell death in kidney, liver, and spleen. We also evaluated whether heme-mediated-inflammatory effects were prevented by TLR4 inhibition with the compound TAK-242, both in vivo and in vitro. Induction of massive hemolysis elicited acute kidney injury characterized by loss of renal function, morphological alterations of the tubular epithelium, cell death, and inflammation. These pathological effects were significantly ameliorated in the TLR4-deficient mice and in wildtype mice treated with TAK-242. In vitro studies showed that TAK-242 pretreatment reduced heme-mediated inflammation by inhibiting the TLR4/NF-κB (nuclear factor kappa B) axis. However, analysis in liver and spleen indicated that TLR4 deficiency did not protect against the toxic accumulation of heme in these organs. In conclusion, TLR4 is a key molecule involved in the renal inflammatory response triggered by massive intravascular hemolysis. TLR4 inhibition may be a potential therapeutic approach to prevent renal damage in patients suffering from hemolysis. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.