Farnesoid X Receptor Plays a Key Role in Ochratoxin A-Induced Nephrotoxicity by Targeting Ferroptosis In Vivo and In Vitro.

The mycotoxin ochratoxin A (OTA) causes nephrotoxicity, hepatotoxicity, and immunotoxicity in animals and humans. The farnesoid X receptor (FXR) is a member of the NR family and is highly expressed in the kidney, which has an antilipid production function. Ferroptosis is an iron-dependent form of regulated cell death involved in several pathophysiological cell death and kidney injury. The present study aims to evaluate the role of FXR and ferroptosis in OTA-induced nephrotoxicity in mice and HK-2 cells. Results showed that OTA induced nephrotoxicity as demonstrated by inducing the histopathological lesions and neutrophil infiltration of the kidney, increasing serum BUN, CRE, and UA levels, increasing Ntn-1, Kim-1, and pro-inflammatory cytokine expression, and decreasing IL-10 expression and the cell viability of HK-2 cells. OTA treatment also induced FXR deficiency, ROS release, MDA level increase, GSH content decrease, and 4-HNE production in the kidney and HK-2 cells. OTA treatment induced ferroptosis as demonstrated by increasing labile iron pool and lipid peroxidation levels as well as Acsl4, TFR1, and HO-1 mRNA and protein levels, decreasing GPX4 and FTH mRNA and protein expressions, and inducing mitochondrial injury. The FXR activator (GW4064) rescued the accumulation of lipid peroxides, intracellular ROS, and Fe2+, inhibited ferroptosis, and alleviated OTA-induced nephrotoxicity. The ferroptosis inhibitor (Fer-1) prevented ferroptosis and attenuated nephrotoxicity. Collectively, this study elucidates that FXR played a critical role in OTA-induced nephrotoxicity via regulation of ferroptosis, which provides a novel strategy against OTA-induced nephrotoxicity.

Expression and immunological characteristics of the surface-localized pyruvate kinase in Mycoplasma gallisepticum.

The widespread avian pathogen Mycoplasma gallisepticum is a causative agent of respiratory disease. The wall-less prokaryotes lack some tricarboxylic acid cycle enzymes, therefore, the glycolysis metabolic pathway is of great importance to these organisms. Pyruvate kinase (PK) is one of the key enzymes of the glycolytic pathway, and its immunological characteristics in Mycoplasma are not well known. In this study, the M. gallisepticum pyruvate kinase fusion protein (PykF) was expressed in a pET system. The full-length of the gene was subcloned into the expression vector pET28a(+) to construct the pET28a-rMGPykF plasmid, which was then transformed into Escherichia coli strain BL21 (DE3) cells. The expression of the 62 kDa recombinant protein of rMGPykF in E. coli strain BL21 (DE3) was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with Coomassie blue staining. Purified rMGPykF exhibited PK catalytic activity, which could reflect the conversion of NADH to NAD(+). Mouse anti-PykF antibodies were generated by immunization of mice with rMGPykF. Immunoblot and immunoelectron microscopy assays identified PykF as an immunogenic protein expressed on the surface of M. gallisepticum cells. Bactericidal assay showed that anti-rMGPykF antiserum killed 70.55% of M. gallisepticum cells, suggesting the protective potential of PykF. Adherence inhibition assay on immortalized chicken fibroblasts (DF-1) cells revealed more than 39.31% inhibition of adhesion in the presence of anti-rMGPykF antiserum, suggesting that PykF of M. gallisepticum participates in bacterial adhesion to DF-1 cells.

A SOE-PCR method of introducing multiple mutations into Mycoplasma gallisepticum neuraminidase.

A modified splicing with overlap extension PCR (SOE-PCR) was generated to introduce 21 TGA to TGG at Mycoplasma gallisepticum MGA_0329 gene. The recombinant protein was successfully expressed and retained neuraminidase activities, indicating that SOE-PCR is a rapid and highly efficient method of introducing multiple mutations into large M. gallisepticum genes.