Objective: To investigate the expressions of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and nuclear factor κBp65 (NF-κBp65) in the renal tissues of obese mice induced by high-fat diet (HFD).
Methods: Forty-five C57BL/6 male mice (8 weeks old) were randomized into HFD group (n=39) and control group (n=6). The mice of the HFD group were fed high-fat and high-glucose diet for 20 weeks, and the others were given the normal diet instead. The body mass was measured weekly. At the end of the 20th week, one-third mice of the HFD group with the highest mass gain were classified as diet-induced obese (DIO) mice (n=13). The DIO mice and control mice were then sacrificed and tissues were collected for further use. The white adipose tissues (epididymal and perirenal fat pads) were removed and weighed. The levels of the serum creatinine (Cre), blood urea nitrogen (BUN) and lipopolysaccharide (LPS) were measured. The morphology of the renal tissues in both groups was studied by HE staining and microscopy. The levels of TLR2, TLR4, MyD88, NF-κBp65 and tumor necrosis factorα (TNF-α) mRNAs in the renal tissues were detected by the real-time quantitative PCR (qRT-PCR), and the levels of TLR4, MyD88 and NF-κBp65 proteins were determined by Western blotting.
Results: Compared with the control group, the serum LPS level showed significantly increased in DIO mice; however, no difference was found between the two groups in the serum Cre and BUN as well as in renal morphological structure. What's more, except that TLR2 mRNA level was not significantly different between the two groups, the mRNA levels of TLR4, MyD88, NF-κBp65 and TNF-α in the renal tissues of the DIO mice were significantly higher than those in the control group, and the protein levels of TLR4, MyD88 and NF-κBp65 in the renal tissues of the DIO mice were also elevated significantly.
Conclusion: The levels of TLR4 and related proinflammatory signaling molecules increased in the renal tissues of obese mice induced by high-fat diet.