Neuregulin 4 attenuate tubulointerstitial fibrosis and advanced glycosylation end products accumulation in diabetic nephropathy rats via regulating TNF-R1 signaling.

Neuregulin 4 (Nrg4) play important roles in the pathogenesis of obesity-associated disorders, including type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD). This study aims to investigate roles of Nrg4 in the pathophysiologic mechanism underlying the progression of tubulointerstitial fibrosis (TIF) in diabetic nephropathy (DN). In present study, Nrg4 is under-expression in serum and renal tissue of diabetic nephropathy rats. In present study, Nrg4 attenuate renal function injury, tubulointerstitial fibrosis, inflammation and suppress the expression levels of advanced glycosylation end products (AGEs) in vivo and vitro. Furthermore, the results reveal that Nrg4 ameliorates fibrosis and attenuate the expression of AGEs and inflammation via TNF-R1 signaling instead of TNF-R2 signaling in HK-2 cells. In conclusion, these results revealed that Nrg4 may effectively ameliorates TIF and attenuate the expression of AGEs in DN through TNF-R1 signaling instead of TNF-R2 signaling. We have provided evidence indicating that Nrg4 possesses therapeutic effect on TIF in DN.

High-Level Secretory Expression and Purification of Recombinant Human Interleukin 1 Beta in Pichia pastoris.

As an important pro-inflammatory cytokine, interleukin-1beta (IL-1ß) participates in a variety of physiological and pathological responses. In order to obtain higher yielded recombinant human interleukin-1 beta (rhIL-1ß), we cloned hIL-1ß cDNA sequences based on the coding sequence of human mature IL-1ß. After recombinant pPICZαA/hIL-1ß was separated and sequenced, we transformed recombinant pPICZαA/hIL-1ß into Pichia pastoris GS115, SMD1168 and X-33 strain via electroporation. The results showed that recombinant pPICZαA/ hIL-1ß had the highest expression level in X-33 Pichia pastoris. Subsequently, rhIL-1ß was purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and identified by Western blot. Then the fermentation process was optimized to increase product yield. Under the fermentation conditions of the absorption value of fermentation liquor before induction of 600, oxygen concentration of 20%, methanol concentration of 0.25% with pH 5.0, the yield of rhIL-1ß reached to 250 mg/L after 72 h induction at 26°C. After aqueous two-phase extraction combined with chromatography, the purity of rhIL-1ß was 95% and the yield was up to 85%. The biological activity of rhIL-1ß was detected by MTT assay, and the result showed that rhIL-1ß significantly inhibited the growth and proliferation of B16 melanoma cells.