Hypertension is a condition associated with oxidative stress, endothelial dysfunction, and increased vascular resistance, representing probably both a cause and a consequence of elevated levels of reactive oxygen (ROS) and nitrogen (RNS) species. Mitochondria are important sites of ROS production, and a mitochondrial dysfunction, preceding endothelial dysfunction, might favor the development of hypertension. ROS production may also be induced by RNS, which inhibit the respiratory chain and may be generated through the action of a mitochondrial NO synthase. Mitochondrial uncoupling proteins are involved in both experimental and human hypertension. Finally, an excessive production of ROS may damage mitochondrial DNA, with resultant impairment in the synthesis of some components of the respiratory chain and further ROS production, a vicious cycle that may be implicated in hypertensive states.
Introduction: Cogan's syndrome (CS) is a rare autoimmune disease, characterized by ocular and vestibulo-auditory involvement. Treatment of CS could be challenging, and the only evidence-based data comes from case reports or series.Areas covered: There have recently been several reports of new treatment strategy involving the use of biological disease-modifying anti-rheumatic drugs such as TNFα inhibitors, anti-CD20 or anti-IL6 receptor antibodies, in cases resistant to first- or second-line drugs.Expert commentary: Corticosteroids are the cornerstone of CS therapy at disease onset and during acute phases of the disease. Conventional immunosuppressive therapy, such as methotrexate, could be used in relapsing patients or as a glucocorticoid sparing agent, but efficacy is often modest. The anti-TNFα monoclonal antibody Infliximab appears to be the most frequently used, leading to an improvement in hearing loss in 89% of the cases and allow corticosteroid tapering in 86% of the patients. The appropriate timing of Infliximab treatment has yet to be thoroughly investigated, but it seems to be more effective when started at an early stage of the disease. Efficacy of others anti-TNFα agents is controversial. Rituximab and Tocilizumab are a safe option, but results on hearing loss have still to be confirmed on larger patients' cohorts.
Abstract An important role in atherogenesis is played by oxidative stress, which may be induced by common risk factors. Mitochondria are both sources and targets of reactive oxygen species, and there is growing evidence that mitochondrial dysfunction may be a relevant intermediate mechanism by which cardiovascular risk factors lead to the formation of vascular lesions. Mitochondrial DNA is probably the most sensitive cellular target of reactive oxygen species. Damage to mitochondrial DNA correlates with the extent of atherosclerosis. Several cardiovascular risk factors are demonstrated causes of mitochondrial damage. Oxidized low density lipoprotein and hyperglycemia may induce the production of reactive oxygen species in mitochondria of macrophages and endothelial cells. Conversely, reactive oxygen species may favor the development of type 2 diabetes mellitus, mainly through the induction of insulin resistance. Similarly - in addition to being a cause of endothelial dysfunction, reactive oxygen species and subsequent mitochondrial dysfunction - hypertension may develop in the presence of mitochondrial DNA mutations. Finally, other risk factors, such as aging, hyperhomocysteinemia and cigarette smoking, are also associated with mitochondrial damage and an increased production of free radicals. So far clinical studies have been unable to demonstrate that antioxidants have any effect on human atherogenesis. Mitochondrial targeted antioxidants might provide more significant results.
