Suppressor of Cytokine Signaling 1–Derived Peptide Inhibits Janus Kinase/Signal Transducers and Activators of Transcription Pathway and Improves Inflammation and Atherosclerosis in Diabetic Mice

Abstract

Objective-Activation of Janus kinase/signal transducers and activators of transcription (STAT) pathway by hyperglycemia and dislypidemia contributes to the progression of diabetic complications, including atherosclerosis. Suppressor of cytokine signaling (SOCS) proteins negatively regulate Janus kinase/STAT and have emerged as promising target for anti-inflammatory therapies. We investigated whether a cell-permeable lipopeptide corresponding to the kinase inhibitory region of SOCS1 could reduce atherosclerosis in diabetic mice and identified the mechanisms involved. Approach and Results-Streptozotocin-induced diabetic apolipoprotein E-deficient mice (aged 8 and 22 weeks) were given intraperitoneal injections of vehicle, SOCS1-derived peptide, or control mutant peptide for 6 to 10 weeks. SOCS1 therapy suppressed STAT1/STAT3 activation in atherosclerotic plaques of diabetic mice and significantly reduced lesion size at both early and advanced stages of lesion development compared with vehicle group. Plaque characterization demonstrated that SOCS1 peptide decreased the accumulation of lipids, macrophages, and T lymphocytes, whereas increasing collagen and smooth muscle cell content. This atheroprotective effect was accompanied by systemic (reduced proinflammatory Ly6C high monocytes and splenic cytokine expression) and local (reduced aortic expression of chemokines and cytokines) mechanisms, without impact on metabolic parameters. In vitro, SOCS1 peptide dose dependently inhibited STAT1/ STAT3 activation and target gene expression in vascular smooth muscle cells and macrophages and also suppressed cytokine-induced cell migration and adhesion processes. Conclusions-SOCS1-based targeting

Targeting HSP90 Ameliorates Nephropathy and Atherosclerosis Through Suppression of NF-κB and STAT Signaling Pathways in Diabetic Mice

“…Accordingly, the efficacy of HSP90 inhibitors in animal models has been linked to the disruption of the IKK complex and JAK2 protein stability, further inhibiting downstream transcription factors such as p50/p65 NF-kB (44) and STAT1/STAT3/STAT5 (45). Dysregulated NF-kB and STAT pathways contribute to diabetic nephropathy and atherosclerosis by inducing the transcription of many genes associated with inflammation, renal fibrosis (45)(46)(47), and the proatherogenic state (23,48). We have previously tested a number of potential novel approaches (e.g., kinase inhibitors, permeable peptides, and gene therapy) to tackle diabetic nephropathy and atherosclerosis by separately inhibiting the STAT and NF-kB pathways (23,26,28,29).…”

“…Dysregulated NF-kB and STAT pathways contribute to diabetic nephropathy and atherosclerosis by inducing the transcription of many genes associated with inflammation, renal fibrosis (45)(46)(47), and the proatherogenic state (23,48). We have previously tested a number of potential novel approaches (e.g., kinase inhibitors, permeable peptides, and gene therapy) to tackle diabetic nephropathy and atherosclerosis by separately inhibiting the STAT and NF-kB pathways (23,26,28,29). Here, we demonstrated that DMAG treatment resulted in combined inhibition of the NF-kB and STAT pathways and subsequent downregulation of their inducible genes (e.g., cytokines, chemokines, and extracellular matrix proteins) both in diabetic mice and in vitro.…”

“…Experimental diabetes model of insulin deficiency was induced in 10-week-old male apolipoprotein E-deficient (apoE 2/2 ) mice by two daily intraperitoneal injections of streptozotocin (STZ, 125 mg/kg/day; Sigma-Aldrich, St. Louis, MO) (22)(23)(24)(25). Animals maintained on standard diet were monitored every 2-3 days for body weight and nonfasting blood glucose.…”

“…Positive staining was expressed as percentage of total plaque area or number of positive cells per lesion area (26,27). Activated NF-kB in kidney and aorta was detected by Southwestern histochemistry using digoxigenin-labeled probes (26,28 (23). Murine monocyte/macrophage cell line (RAW 264.7, TIB-71; ATCC) was maintained in DMEM with 10% FBS.…”

Peptide-based inhibition of IκB kinase/nuclear factor-κB pathway protects against diabetes-associated nephropathy and atherosclerosis in a mouse model of type 1 diabetes

“…In vitro studies Primary mouse mesangial cells (MC), vascular smooth muscle cells (VSMC) and a proximal tubuloepithelial cell line (MCT) were cultured in medium containing 10% FCS (Life Technologies, Rockville, MD, USA) [21][22][23][24]. Quiescent cells were treated for 90 min with peptides before short-term incubation with high glucose (HG; 30 mmol/l D-glucose, 60 min) or lipopolysaccharide (LPS; 1 μg/ml, 30 min; Sigma-Aldrich, St Louis, MO, USA).…”