Fructosylation generates neo-epitopes on human serum albumin.

Hyperglycemia is the defining feature of diabetes mellitus. The persistently high levels of reducing sugars like glucose and fructose cause glycation of various macromolecules in the body. Human serum albumin (HSA), the most abundant serum protein with a myriad of functions, is prone to glycation and consequent alteration in its structural and biological properties. This study aimed to assess the role of fructose-modified human serum albumin as a marker of diabetic pathophysiology. We carried out modification of HSA with fructose and the changes induced were studied by various physicochemical studies. Fructose modified-HSA showed hyperchromicity in UV spectrum and increased AGE-specific fluorescence as well as quenching of tryptophan fluorescence. In SDS-PAGE protein aggregation was seen. Amadori products were detected by NBT. The fructose modified HSA had higher content of carbonyls along with perturbations in secondary structure as revealed by CD and FT-IR. A greater hydrodynamic radius of fructose-modified HSA was evident by DLS measurement. The fructose-modified HSA induced high titre antibodies in experimental animals exhibiting high specificity towards the immunogen.

Levels of anti-fructose-modified HSA antibodies correlate with disease status in diabetic subjects.

OBJECTIVE: This study aimed to assess the changes induced in HSA upon fructose-modification and to use the modified protein as an antigen for studying the presence of antibodies in diabetic patients. Further, magnitude of oxidative stress was also assessed. METHODS: HSA was modified with fructose, changes induced were studied by DSC measurements and near-UV CD. The binding characteristics of antibodies in the sera of diabetes patients to native and modified-HSA was assessed by ELISA and band shift assay. The oxidative stress in these patients was studied by carbonyl content estimation, FRAP assay and TBARS determination RESULTS: DSC revealed that fructose modified-HSA was more thermostable than its native form. Changes in tertiary structure of fructose-modified HSA were seen in near-UV CD. Patient studies showed that fructose-modified HSA acts as a potent immunogen compared to its native form and the levels of antibodies against fructose-modified HSA served as a parameter for tracking the glycemic control and oxidative stress parameters (carbonyl content, FRAP value and MDA level) in diabetic patients. CONCLUSIONS: Fructose-modification of HSA causes perturbations in its structure and function, thereby, making the protein antigenic besides decreasing its antioxidant capacity. This study suggests that fructose-modified-HSA is an important contributor in diabetic pathophysiology.

The relationship between C-reactive protein and prognostic factors in chronic obstructive pulmonary disease.

BACKGROUND: The purpose of the study was to determine the relationship between high sensitivity C-reactive protein (hs-CRP) levels and prognostic factors in chronic obstructive pulmonary disease. METHODS: We studied 50 stable COPD patients with: spirometry, 6 minute walk distance, body mass index, GOLD stage (spirometric classification) and smoking status. In these patients hs-CRP values were measured and compared with those of 50 healthy controls. Then the serum hs-CRP was subjected to evaluation for any correlation with the predictors of outcomes in COPD subjects. RESULTS: Hs-CRP levels were higher in COPD patients than in controls (4.82 vs. 0.88 mg/L p < 0.01). Correlation was found between hs-CRP and the following variables: FEV1 (r= -0.813; p < 0.01), 6MWD (r= -0.876; p < 0.01), body mass index (r= -0.710; p < 0.01), GOLD stage (r= 0.797, p < 0.01) and smoking status (r= 0.796; p < 0.01). Using multivariate analysis, FEV1 and 6MWD showed the strongest negative association with hs-CRP levels. CONCLUSIONS: The circulating levels of the inflammatory marker hs-CRP are significantly elevated in patients with COPD, supporting the view that COPD is in part an inflammatory disorder. Hs-CRP levels in stable COPD patients are best correlated with FEV1 and 6-minute walk distance (6MWD). This information should be considered when hs-CRP levels are measured in stable COPD patients.