Elevated retinol binding protein 4 levels are associated with atherosclerosis in diabetic rats via JAK2/STAT3 signaling pathway

BACKGROUND Atherosclerosis is a major cause of mortality worldwide and is driven by multiple risk factors,including diabetes,which results in an increased atherosclerotic burden,but the precise mechanisms for the occurrence and development of diabetic atheroscerosis have not been fully elucidated.AIM To summarize the potential role of retinol binding protein 4(RBP4) in the pathogenesis of diabetic atheroscerosis,particularly in relation to the RBP4-Janus kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3)signaling pathway.METHODS Male Wistar rats were randomly divided into three groups,including a control group(NC group),diabetic rat group(DM group),and diabetic atherosclerotic rat group(DA group).The contents of total cholesterol(TC), high-density lipoprotein cholesterol(HDL-c), triglycerides(TG), low-density lipoprotein cholesterol(LDLc), fasting insulin(FINS),fasting plasma glucose,and hemoglobin A1 c(HbA1 c)were measured.Moreover,the adipose and serum levels of RBP4,along with the expression levels of JAK2, phosphorylated JAK2(p-JAK2), STAT3,phosphorylated STAT3(p-STAT3), B-cell lymphoma-2(Bcl-2), and Cyclin D1 in aortic tissues were also measured.Besides,homeostasis model assessment of insulin resistance(HOMA-IR) and atherogenic indexes(AI) were calculated.RESULTS Compared with the NC and DM groups,the levels LDL-c,TG,TC,FINS,HOMAIR,RBP4,and AI were upregulated,whereas that of HDL-c was downregulated in the DA group(P <0.05);the mRNA levels of JAK2,STAT3,Cyclin D1,and Bcl-2 in the DA group were significantly increased compared with the NC group and the DM group;P-JAK2,p-JAK2/JAK2 ratio,p-STAT3,p-STAT3/STAT3 ratio,Cyclin D1,and Bcl-2 at protein levels were significantly upregulated in the DA group compared with the NC group and DM group.In addition,as shown by Pearson analysis,serum RBP4 had a positive correlation with TG,TC,LDL-c,FINS,HbA1 C,p-JAK2,p-STAT3,Bcl-2,Cyclin D1,AI,and HOMA-IR but a negative correlation with HDL-c.In addition,multivariable logistic regression analysis showed that serum RBP4,p-JAK2,p-STAT3,and LDL-c were predictors of the presence of diabetic atherosclerosis.CONCLUSION RBP4 could be involved in the initiation or progression of diabetic atherosclerosis by regulating the JAK2/STAT3 signaling pathway.

PLA_(2) mediates the innate immune response in Asian corn borer, Ostrinia furnacalis

The eicosanoid signaling pathway mediates insect immune reactions to a wide range of stimuli. This pathway begins with the biosynthesis of arachidonic acid (AA) from the hydrolysis of phospholipids catalyzed by phospholipase A_(2) (PLA_(2)). We report here that the PLA_(2) inhibitor, dexamethasone (DEX), impaired the innate immune response including nodulation, encapsulation, and melanization in Ostrinia furnacalis larvae, while AA partially reversed these effects of DEX. We cloned a full-length complementary DNA encoding a PLA_(2), designated as OfsPLA_(2), from O. furnacalis. The open reading frame of OfsPLA_(2) encodes a 195-amino acid residue protein with a 22-residue signal peptide. Sequence alignment analyses indicated that O. furnacalis PLA_(2) might be a Group III secretory PLA_(2). The highest transcript levels of OfsPLA_(2) were detected in the fat body, and its transcript levels increased dramatically after infection with Escherichia coli, Micrococcus luteus, or Beauveria bassiana. Recombinant OfsPLA_(2) significantly induced prophenoloxidase (PPO) activation in larval hemolymph in the presence of Ca^(2+) and encapsulation of agarose beads. Injection of recombinant OfsPLA_(2) into larvae resulted in increased transcript levels of attacin, defencin, and moricin-3 genes. Our results demonstrate the involvement of the eicosanoid signaling pathway in the innate immune response of O. furnacalis larvae and provide new information about the roles of O. furnacalis secretory PLA_(2) in activating PPO and antimicrobial peptide production.