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Background: Proprotein convertase subtilisin/kexin type-9 (PCSK-9) is a serine protease with profound effects on plasma LDL-C, the major risk factor for cardiovascular diseases (CVDs). However, plasma PCSK-9 level and its association with the biomarkers of CVDs, diabetes, and associated complications have not yet been reported in the northeastern population of India. Methods: Of the total cohort (n = 233), we analyzed healthy controls (HC; n = 50), freshly diagnosed type-2-diabetes mellitus (T2DM-FD; n = 46), T2DM treated (T2DM-T; n = 49), diabetic nephropathy (T2DM-N; n = 43), and diabetic dyslipidemia (T2DM-DL; n = 45) subjects. Plasma PCSK-9 and other biological determinants associated with T2DM, CVD, and nephrotic dysfunction were assessed. Results: The level of plasma PCSK-9 in HC, T2DM-FD, T2DM-T, T2DM-N, and T2DM-DL groups was found to be 184.1 ± 13.83, 183.1 ± 24.4.3, 241.8 ± 75.42, 403.7 ± 85.94, and 641.3 ± 135.5 ng/mL, respectively, indicating its role in the severity of the here-mentioned complications. Moreover, plasma PCSK-9 levels further showed a significant correlation with the biomarkers of hyperglycemia, particularly HbA1c, as well as LDL-C in T2DM-FD, T2DM-N, and T2DM-DL subjects of the Indian population, while moderate association in T2DM-T subjects. Conclusions: Our first-of-its-kind clinical study aiming to quantify the circulatory PCSK-9 level in the Indian population concluded that elevated PCSK-9 was significantly associated with the severity of diabetes and associated complications. Moreover, such elevation in PCSK-9 might be attributed to the lipid- and glucose-lowering medication-induced SREBP-2-dependent mechanisms. Since our conclusion is based on a pilot study, further cohort studies in larger populations of India are required to get a generalization regarding the role of PCSK-9 in DM and associated complications. [ABSTRACT FROM AUTHOR]

Methylglyoxal (MG) is a precursor for advanced glycation end-products (AGEs), which have a significant role in diabetes. The present study is designed to probe the immunological response of native and glycated low-density lipoprotein (LDL) in experimental animals. The second part of this study is to probe glycoxidative lesion detection in low-density lipoproteins (LDL) in diabetes subjects with varying disease duration. The neo-epitopes attributed to glycation-induced glycoxidative lesion of LDL in DM patients' plasma were, analyzed by binding of native and MG-modified LDL immunized animal sera antibodies using an immunochemical assay. The plasma purified human LDL glycation with MG, which instigated modification in LDL. Further, the NewZealand-White rabbits were infused with unmodified natural LDL (N-LDL) and MG-glycatedLDL to probe its immunogenicity. The glycoxidative lesion detection in LDL of DM with disease duration (D.D.) of 5–15 years and D.D. > 15 years was found to be significantly higher as compared to normal healthy subjects (NHS) LDL. The findings support the notion that prolonged duration of diabetes can cause structural alteration in LDL protein molecules, rendering them highly immunogenic in nature. The presence of LDL lesions specific to MG-associated glycoxidation would further help in assessing the progression of diabetes mellitus. [ABSTRACT FROM AUTHOR]

Background. Pro- and antiatherogenic properties of oxidised low density lipoprotein (Ox-LDL) are responsible for different chronic diseases including diabetes and cardiovascular diseases (CVD). The constant attack on the body from oxidative stress makes the quantification of various oxidation products necessary. In this study, the oxidative stress causing the structural and chemical changes occurring in the LDL molecule is comprehensively done. Moreover, the prevalence of the autoantibodies against the oxidised LDL is also determined. Methods. Our study made an attempt to see the effect of Ox-LDL as an enhancer of type 2 diabetes mellitus (T2DM) coupled with CVD. Primarily, we detected the oxidation of LDL with different concentration of Fenton reaction. The biochemical parameters were assessed for the changes occurring in the LDL molecule. In a clinical set up, 20 sera samples were taken from patients who are healthy, 30 from those with diabetes, 20 from those with CVD, and 30 from diabetes with CVD patients. Results. In biochemical assays there were markedly increased TBARS, carbonyl, and HMF content in Ox-LDL as compared to native LDL. The prevalence of autoantibodies against the T2DM was recorded to be 36%, while for CVD it was recorded to be 29%. However, it was found that 50% of the sera samples showed autoantibodies against oxidized LDL in the sera of T2DM with CVD complications as compared to the native analogue. Conclusion. There is significant change in the LDL molecule as revealed by various physicochemical analysis. The change in the LDL macromolecule as a result of oxidation triggered the development of the autoantibodies against it. [ABSTRACT FROM AUTHOR]

Advanced glycation end products (AGEs) are thought to contribute to the abnormal lipoprotein profiles and increased risk of cardiovascular disease in patients with diabetes and renal failure. D-ribose is one of the naturally occurring pentose monosaccharide present in all living cells and is a key component of numerous biomolecules involved in many important metabolic pathways. Formation of D-ribose derived glycated low density lipoprotein (LDL) has been previously demonstrated but no studies have been performed to assess the immune complex deposition in the kidney of rabbits immunized with glycated LDL. In this study, LDL was glycated with D-ribose, and it was further used as an immunogen for immunizing NZW female rabbits. The results showed that female rabbits immunized with D-ribose modified LDL induced antibodies as detected by direct binding and competitive ELISA. The modified LDL was found to be highly immunogenic eliciting high titer immunogen-specific antibodies, while the native forms were moderately immunogenic. The induced antibodies from modified LDL exhibited wide range of heterogeneity in recognizing various proteins and amino acids conformers. Furthermore, our histopathological results illustrated the deposits of immune complex in glomerular basement membrane in rabbits immunized with D-ribose-LDL. [ABSTRACT FROM AUTHOR]

Abstract: Glycation of biomolecules leads to the establishment of advanced glycation end products (AGEs), which have significant role in the pathophysiology of diabetes leading to disorders, such as atherosclerosis. Ribose appears to be the most reactive among the naturally occurring sugars and contribute significantly to the glycation reactions in vivo, however, no report has been published to discuss d-ribose induced glycation of low density lipoprotein (LDL). The present study initially focuses on the glycation of commercially available LDL using different concentrations of d-ribose for varied incubation time intervals. The structural perturbations induced in LDL were analyzed by UV–vis, fluorescence & circular dichroism spectroscopy, and thermal denaturation studies. The ketoamine moieties, carbonyl content and HMF content were also quantitated in native and glycated LDL. We report structural perturbations, increased carbonyl content, ketoamine moieties and HMF content in d-ribose induced glycated LDL (LDL-AGEs) as compared to native analogue. These results provide evidence that LDL-AGEs could interfere in normal physiological functions and might contribute in the initiation of diabetes induced atherosclerosis and other secondary cardiovascular problems in diabetic patients. Though ours is a preliminary study, we are sure it would open the topic for further studies. [Copyright &y& Elsevier]

Glycation initiates with the non-enzymatic reaction of amino group of proteins and lipoproteins by carbonyl group of sugar moiety and intermediates of glycative stress such as methylglyoxal (MG). The initial glycation leads to the formation of early glycation products (Amadori products) which undergo rearrangement, cyclization and dehydration to form advanced glycation end products (AGEs). The main objective of the present study is to investigate the non-enzymatic glycation of low density lipoprotein (LDL) by MG at different concentration and at increasing incubation time period in vitro . This modification may increase the formation of Amadori products and AGEs which are physico-chemically characterized with respect to the extent of LDL modification. Additionally, immunogenicity of native and MG modified LDL (MG-LDL) was probed in female rabbits in vivo . Immunogenicity of MG-LDL was found to be highly immunogenic, eliciting high titer immunogen-specific antibodies while native form of LDL is less immunogenic. Furthermore, the histopathology and immune-fluorescence studies suggest that the kidney section of immunized rabbits exhibit the presence of immune complex (MG-LDL-IgG) deposition in the glomerular basement membrane (GBM). [ABSTRACT FROM AUTHOR]

Methylglyoxal (MGO), a reactive dicarbonyl metabolite is a potent arginine directed glycating agent which has implications for diabetes-related complications. Dicarbonyl metabolites are produced endogenously and in a state of misbalance, they contribute to cell and tissue dysfunction through protein and DNA modifications causing dicarbonyl stress. MGO is detoxified by glyoxalase 1 (GLO1) system in the cytoplasm. Reactive oxygen species (ROS) are known to aggravate the glycation process. Both the processes are closely linked, and their combined activity is often referred to as “glycoxidation” process. Glycoxidation of proteins has several consequences such as type 2 diabetes mellitus (T2DM), aging etc. In this study, we have investigated the glycation of low-density lipoprotein (LDL) using different concentrations of MGO for varied incubation time periods. The structural perturbations induced in LDL were analyzed by UV–Vis, fluorescence, circular dichroism spectroscopy, molecular docking studies, polyacrylamide gel electrophoresis, FTIR, thermal denaturation studies, Thioflavin T assay and isothermal titration calorimetry. The ketoamine moieties, carbonyl content and HMF content were quantitated in native and glycated LDL. Simulation studies were also done to see the effect of MGO on the secondary structure of the protein. We report structural perturbations, increased carbonyl content, ketoamine moieties and HMF content in glycated LDL as compared to native analog (native LDL). We report the structural perturbations in LDL upon modification with MGO which could obstruct its normal physiological functions and hence contribute to disease pathogenesis and associated complications. [ABSTRACT FROM AUTHOR]

Glycation of biologically important macromolecules leads to the establishment of advanced glycation end products (AGEs) having significant role in the pathophysiology of various diseases. d -Ribose, is a highly reactive pentose sugar resulting in the rapid formation of AGEs. Formation of d -ribose derived glycated DNA and LDL has been previously demonstrated; however no comparative, extensive studies have been performed to assess the immunogenicity of d -ribose glycated calf thymus DNA (CT-DNA) and LDL. In the present study, the results showed that animals immunized with d -ribose modified CT-DNA and LDL induced antibodies as detected by direct binding and competition ELISA. The modified CT-DNA and LDL were found to be highly immunogenic, eliciting high titer immunogen-specific antibodies, while the native forms of DNA was almost non-immunogenic. The induced antibodies from modified CT-DNA and LDL exhibited wide range of heterogeneity in recognizing various nucleic acid conformers, DNA bases and amino acids. Furthermore, Serum antibodies from diabetes and diabetes atherosclerosis patients were screened for their binding to native CT-DNA, LDL and glycated CT-DNA, LDL. Glycated CT-DNA showed almost equivalent binding to both diabetes and diabetic atherosclerosis group while high recognition was observed when glycated LDL was used as an antigen. [ABSTRACT FROM AUTHOR]

Abstract Advanced glycation end-products (AGEs) can aggregate amid incessant inflammation, as may be available in patients with rheumatoid arthritis. d -Ribose reacts more promptly than glucose monosaccharide to the proteins and forms heterogeneous group of products known as AGEs. Obesity includes persons with provocative joint inflammation with increased lipid profile. Immunogenic evidences recommend a cross-sectional relationship between glycated LDL-Apo B100 and inflammation. The point of this examination was to look at the connection between d -ribose glycated ApoB100 (ApoB100-AGE) with obesity and rheumatoid arthritis. The binding specificity of auto-antibodies against ApoB100-AGE antigen present in obesity and rheumatoid arthritis patient's serum were inspected by direct binding and was further established by competitive inhibition ELISA. In the present study, hydroxyl radical, superoxide radical, ketoamine moieties, hydroxyl-methyl furfural (HMF) and carbonyl substances were evaluated in the patients' serum via respective specific methods. The prevalence of auto-antibodies against ApoB100-AGE antigen was recorded to be 58% and 52.86% from obese and rheumatoid arthritis patient respectively in contrast to its native analogue (P < 0.001). Moreover, the autoantibodies present in obese and arthritis patients were found to be highly specific towards ApoB100-AGE as confirmed by inhibition ELISA. Highlights • The keto-amine moieties, HMF and carbonyl substance were higher in obese and Arthritic patient sera. • High degree of specificity in 80% obese and 73% rheumatoid sera against Apo-B100-AGE-IgG was obtained. • In obese and Rheumatoid sera, inhibition with glycated ApB 100 was 87% and 64% respectively. [ABSTRACT FROM AUTHOR]

Aims Glycation of proteins leads to the formation of advanced glycation end products (AGEs, which have significant role in the pathophysiology of diabetes complications. d -ribose appears to be the most reactive among the naturally occurring sugars and contribute significantly to the generation of AGEs. Glycation also results in the generation of free radicals causing structural modification which leads to the generation of neoantigenic epitopes. The aim of the present study was to investigate whether LDL modification results in auto-antibodies formation against its glycated conformer in diabetes and atherosclerosis patients. Methods The binding characteristics of circulating auto-antibodies in patients against native and modified LDL were assessed. T2D ( n = 105), ATH ( n = 106) and T2D-ATH patients ( n = 72) were examined by direct binding ELISA as well as inhibition ELISA, compared with healthy ag e -matched controls ( n = 50). Furthermore, ketoamine moieties, HMF and carbonyl content were also estimated in these patient's and healthy subjects. Key findings High degree of specific binding was observed by 41.91% of T2D, 54.72% of ATH and 70.83% T2D-ATH patient's sera towards d -ribose glycated LDL, in comparison to its native analog ( P < 0.05). Normal human sera showed negligible binding with either antigen. Competitive inhibition ELISA reiterates the direct binding results. The higher concentration of HMF, ketoamine and carbonyl content was observed in patient's sera than healthy subjects. Significance LDL glycation results in structural perturbation causing generation of neoantigenic epitopes that are better antigens for antibodies in T2D, ATH and T2D-ATH patients where T2D-ATH subjects showed higher prevalence in auto-antibodies against ribosylated LDL. [ABSTRACT FROM AUTHOR]

• Non-enzymatic reaction of biomolecules leads to AGEs formation. • AGEs results in the structural perturbations. • AGEs may lead to generation of neo-antigenic epitopes on LDL molecules. • The neo-antigenic epitopes on LDL macromolecule results in antibody generation. Non-enzymatic reaction of biomolecules leads to the formation of advanced glycation end products (AGEs). AGEs plays significant role in the pathophysiology of type 2 diabetes mellitus. Methylglyoxal (MG) is a highly reactive carbonyl compound which causes formation of early (ketoamines), intermediate (dicarbonyls) and advanced glycation end products (AGEs). Glycation also results in the generation of free radicals causing structural perturbations which leads to the generation of neoantigenic epitopes on LDL molecules. The aim of the present study was to investigate whether the modification of LDL results in auto-antibodies generation in type 2 diabetes patients'. The binding affinity of circulating autoantibodies in patients against native and MG modified LDL were assessed as compared with healthy and age-matched controls (n = 50) and T2DM patients with disease duration (DD) 5–15 yrs (n = 80) and DD > 15 yrs (n = 50) were examined by direct binding ELISA. The high affinity binding were observed in 50% of T2DM with DD 5–15 and 62% of T2DM with DD > 15 of patient's sera antibodies to MG-LDL antigen, in comparison to its native analog (P < 0.05). NHS sera showed negligible binding with both native and glycated LDL. Competitive inhibition ELISA results exhibit greater affinity sera IgG than the direct binding ELISA results. The increase in glycation intermediate and ends product were also observed in T2DM patient's sera and NHS sera. There might be the generation of neoantigenic epitopes on LDL macromoleucle which results in generation of antibodies in T2DM. The prevalence of antibodies was dependent on disease duration. [ABSTRACT FROM AUTHOR]