Study of Albumin Oxidation in COVID-19 Pneumonia Patients: Possible Mechanisms and Consequences

Oxidative stress induced by neutrophils and hypoxia in COVID-19 pneumonia leads to albumin modification. This may result in elevated levels of advanced oxidation protein products (AOPPs) and advanced lipoxidation end-products (ALEs) that trigger oxidative bursts of neutrophils and thus participate in cytokine storms, accelerating endothelial lung cell injury, leading to respiratory distress. In this study, sixty-six hospitalized COVID-19 patients with respiratory symptoms were studied. AOPPs-HSA was produced in vitro by treating human serum albumin (HSA) with chloramine T. The interaction of malondialdehyde with HSA was studied using time-resolved fluorescence spectroscopy. The findings revealed a significantly elevated level of AOPPs in COVID-19 pneumonia patients on admission to the hospital and one week later as long as they were in the acute phase of infection when compared with values recorded for the same patients 6- and 12-months post-infection. Significant negative correlations of albumin and positive correlations of AOPPs with, e.g., procalcitonin, D-dimers, lactate dehydrogenase, aspartate transaminase, and radiological scores of computed tomography (HRCT), were observed. The AOPPs/albumin ratio was found to be strongly correlated with D-dimers. We suggest that oxidized albumin could be involved in COVID-19 pathophysiology. Some possible clinical consequences of the modification of albumin are also discussed.

Role of early glycation Amadori products of lysine-rich proteins in the production of autoantibodies in diabetes type 2 patients

In diabetes, protein glycation mostly occurs at intrachain lysine residues resulting in the formation of early stage Amadori products which are finally converted to advance glycation end products (AGEs). Several studies have reported autoantibodies against AGEs in diabetes but not much data are found in respect of Amadori products. In this study, poly-L-lysine (PLL) was glycated with 50 mM glucose and the resultant Amadori products were estimated by fructosamine or nitroblue tetrazolium assay. We report high content of Amadori products in PLL upon glycation. Glycated PLL showed marked hyperchromicity in the UV spectrum, ellipticity changes in CD spectroscopy, and variations in ε-methylene protons shift in NMR. It was better recognized by autoantibodies in type 2 diabetics compared to the native PLL. Induced antibodies against glycated PLL were successfully used to probe early glycation in the IgG isolated from diabetes type 2 patients. Role of Amadori products of glycated proteins in the induction of autoantibodies in type 2 diabetes as well as in associated secondary complications has been discussed.

[Vascular endothelial dysfunction, oxidative stress--a new topic within the referral section of Orvosi Hetilap]

The author describes some of the numerous domains regarding the new topic called "Vascular endothelial dysfunction, oxidative stress". The endothelium is responsible for the constancy and integrity of the milieu interieur by producing various substances. Endothelial dysfunction occurs when there is imbalance between vasodilators and vasoconstrictors, growth factors and their inhibitors, proinflammatory and antiinflammatory agents, prothrombotic and fibrinolytic activities. The reason for this imbalance may be response to vascular endothelial or intimal injury caused by mechanical, physical, chemical, microbiological, immunologic, genetic damage or any of their combination. Endothelial dysfunction occurring on the huge inner surface of the vessels (the endothelium) is responsible for the triggering of atherosclerosis, which is a chronic vascular disease. All the risk factors of vascular pathology are leading to chronic (cardio)vascular diseases by causing endothelial dysfunction. Decreased endogenous antioxidative capacity leads to oxidative stress by free radical reactions of physiological oxidative metabolic processes, ending as the ultimate reason for endothelial dysfunction induced by risk factors. The therapeutic and preventive effects of causal antioxidant treatments having intracellular and mitochondrial effects (statins, angiotensin-converting-enzyme inhibitors, angiotensin-receptor-blockers, acetylsalicylic acid, and third generation beta-blockers) should be emphasized. It is also important to underline the physiological-pathophysiological-therapeutic consubstantiality and systemic nature of human vasculature and to emphasize the preventive-therapeutic significance of the vascular consequence cascade. And finally, there has been large process in the assessment of oxidative stress and consecutive endothelial dysfunction which revolutionized our clinical point of view.