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Methylglyoxal (MG), a glycolytic intermediate and reactive dicarbonyl, is responsible for exacerbation of insulin resistance and diabetic complication. In this study, MG-induced secretome of rat muscle cells was identified and relatively quantified by SWATH-MS. A total of 643 proteins were identified in MG-induced secretome, of which 82 proteins were upregulated and 99 proteins were downregulated by more than 1.3-fold in SWATH analysis. Further, secretory proteins from the classical secretory pathway and nonclassical secretory pathway were identified using SignalP and SecretomeP, respectively. A total of 180 proteins were identified with SignalP, and 113 proteins were identified with SecretomeP. The differentially expressed proteins were functionally annotated by KEGG pathway analysis using Cytoscape software with plugin clusterMaker. The differentially expressed proteins were found to be involved in various pathways like extracellular matrix (ECM)–receptor interaction, leukocyte transendothelial migration, fluid shear stress and atherosclerosis, complement and coagulation cascades, and lysosomal pathway. Since the MG levels are high in diabetic conditions, the presence of MG-induced secreted proteins was inspected by profiling human plasma of healthy and diabetic subjects (n = 10 each). CD44, a predominant MG-induced secreted protein, was found to be elevated in the diabetic plasma and to have a role in the development of insulin resistance.

Background: India has been amongst the most affected nations during the SARS CoV2 pandemic, with sparse data on country wide spread of asymptomatic infections and antibody persistence. This longitudinal cohort study was aimed to evaluate SARS CoV2 seropositivity rate as a marker of infection and evaluate temporal persistence of antibodies with neutralization capability and to infer possible risk factors for infection. Methods: Council of Scientific and Industrial Research, India (CSIR) with its more than 40 laboratories and centers in urban and semi urban settings spread across the country piloted the pan country surveillance. 10427 adult individuals working in CSIR laboratories and their family members based on voluntary participation were assessed for antibody presence and stability was analyzed over 6 months utilizing qualitative Elecysys SARS CoV2 specific antibody kit and GENScript cPass SARS CoV2 Neutralization Antibody Detection Kit. Along with demographic information, possible risk factors were evaluated through self to be filled online forms with data acquired on blood group type, occupation type, addiction and habits including smoking and alcohol, diet preferences, medical history and transport type utilized. Symptom history and information on possible contact and compliance with COVID 19 universal precautions was also obtained. Findings:1058 individuals (10.14%) had antibodies against SARS CoV2. A follow up on 346 seropositive individuals after three months revealed stable to higher antibody levels against SARS CoV2 but declining plasma activity for neutralizing SARS CoV2 receptor binding domain and ACE2 interaction. A repeat sampling of 35 individuals, at six months, revealed declining antibody levels while the neutralizing activity remained stable compared to three months. Majority of seropositive individuals (75%) did not recall even one of nine symptoms since March 2020. Fever was the most common symptom with one fourth reporting loss of taste or smell. Significantly associated risks for seropositivity (Odds Ratio, 95% CI, p value) were observed with usage of public transport (1.79, 1.43 to 2∙24, 2.81561x10-6), occupational responsibilities such as security, housekeeping personnel etc. (2.23, 1.92 to 2.59, 6.43969x10-26), non smokers (1.52, 1.16 to 1.99, 0.02) and non vegetarianism (1.67, 1.41 to 1.99, 3.03821x10-8). An iterative regression analysis was confirmatory and led to only modest changes to estimates. Predilections for seropositivity was noted with specific ABO blood groups; O was associated with a lower risk. Interpretation: In a first of its kind study from India, we report the seropositivity in a country wide cohort and identify variable susceptible associations for contacting infection. Serology and Neutralizing Antibody response provides much sought for general insights on the immune response to the virus among Indians and will be an important resource for designing vaccination strategies. Funding: Council of Scientific and Industrial Research, India (CSIR)

Hyperglycemic condition in diabetes promotes glycation of various plasma proteins including insulin. Glycation of insulin has been reported to reduce its biological activity. Reduced biological activity of glycated insulin could be either due to reduced affinity for the insulin receptor and impaired insulin signaling, or it can act as a ligand for the receptor for advanced glycation end products (RAGE) and activates oxidative stress and pro-inflammatory pathways leading to insulin resistance. This study investigates the effect of glycated insulin on both insulin and RAGE signaling. Glycated insulin treatment to Chinese hamster ovary (CHO-IR-GLUT4) cells stably expressing insulin receptor (IR) and glucose transporter fused with a green fluorescent protein (GLUT4-GFP) resulted in the impairment of insulin signaling, as the phosphorylation of IR and AKT significantly reduced, which affected GLUT4 translocation and glucose uptake. Moreover, it also activated RAGE signaling as observed by increased expression of NADPH oxidase accompanied by an increase in reactive oxygen species (ROS). Immunofluorescence study indicated the translocation of NF-κB to the nucleus upon treatment of glycated insulin. This was associated with increased RAGE expression, Caspase 3, and cell death. Downregulation of RAGE with the losartan treatment restored the impaired insulin signaling and glucose uptake. Additionally, in silico study demonstrated that glycated insulin has reduced binding affinity to insulin receptor and increased binding affinity to RAGE. Overall, this study demonstrates the role of glycated insulin in exacerbating insulin resistance by impairing insulin signaling as well as stimulating AGE-RAGE signaling.