HIV-related vasculitis

The two-edged sword: vasculitis associated with HIV and hepatitis C coinfection

Vasculitis has long been associated with chronic viral infections, thus the twin perils of the infection and the immune response against it that bedevils the specialties of infection and immunity. After HIV was identified, it too became associated with vasculitic syndromes. Later, hepatitis C virus was also isolated, identified and described with its own spectrum of vasculitic diseases, including hepatitis C virus-associated cryoglobulinaemia. With the increasing prevalence of HIV and hepatitis C virus coinfection, there has come an increasing recognition of the range of vasculitides that can occur in this population leading to significant morbidity, diagnostic and treatment challenges. In this review, we examine the epidemiology, pathogenesis and general principles of treatment of these systemic diseases in HIV/hepatitis C virus coinfected individuals.

HIV-1, reactive oxygen species, and vascular complications

Over 1 million people in the United States and 33 million individuals worldwide suffer from HIV/AIDS. Since its discovery, HIV/AIDS has been associated with an increased susceptibility to opportunistic infection due to immune dysfunction. Highly active antiretroviral therapies restore immune function and, as a result, people infected with HIV-1 are living longer. This improved survival of HIV-1 patients has revealed a previously unrecognized risk of developing vascular complications, such as atherosclerosis and pulmonary hypertension. The mechanisms underlying these HIV-associated vascular disorders are poorly understood. However, HIV-induced elevations in reactive oxygen species (ROS), including superoxide and hydrogen peroxide, may contribute to vascular disease development and progression by altering cell function and redox-sensitive signaling pathways. In this review, we summarize the clinical and experimental evidence demonstrating HIV- and HIV antiretroviral therapy-induced alterations in reactive oxygen species and how these effects are likely to contribute to vascular dysfunction and disease.

The roles of HIV-1 proteins and antiretroviral drug therapy in HIV-1-associated endothelial dysfunction

Since the emergence of highly active antiretroviral therapy (HAART), human immunodeficiency virus-1 (HIV-1)-infected patients have demonstrated dramatic decreases in viral burden and opportunistic infections, and an overall increase in life expectancy. Despite these positive HAART-associated outcomes, it has become increasingly clear that HIV-1 patients have an enhanced risk of developing cardiovascular disease over time. Clinical studies are instrumental in our understanding of vascular dysfunction in the context of HIV-1 infection. However, most clinical studies often do not distinguish whether HIV-1 proteins, HAART, or a combination of these 2 factors cause cardiovascular complications. This review seeks to address the roles of both HIV-1 proteins and antiretroviral drugs in the development of endothelial dysfunction because endothelial dysfunction is the hallmark initial step of many cardiovascular diseases. We analyze recent in vitro and in vivo studies examining endothelial toxicity in response to HIV-1 proteins or in response to the various classes of antiretroviral drugs. Furthermore, we discuss the multiple mechanisms by which HIV-1 proteins and HAART injure the vascular endothelium in HIV-1 patients. By understanding the molecular mechanisms of HIV-1 protein- and antiretroviral-induced cardiovascular disease, we may ultimately improve the quality of life of HIV-1 patients through better drug design and the discovery of new pharmacological targets.

Vascular oxidative stress and nitric oxide depletion in HIV-1 transgenic rats are reversed by glutathione restoration

Human immunodeficiency virus (HIV)-infected patients have a higher incidence of oxidative stress, endothelial dysfunction, and cardiovascular disease than uninfected individuals. Recent reports have demonstrated that viral proteins upregulate reactive oxygen species, which may contribute to elevated cardiovascular risk in HIV-1 patients. In this study we employed an HIV-1 transgenic rat model to investigate the physiological effects of viral protein expression on the vasculature. Markers of oxidative stress in wild-type and HIV-1 transgenic rats were measured using electron spin resonance, fluorescence microscopy, and various molecular techniques. Relaxation studies were completed on isolated aortic rings, and mRNA and protein were collected to measure changes in expression of nitric oxide (NO) and superoxide sources. HIV-1 transgenic rats displayed significantly less NO-hemoglobin, serum nitrite, serum S-nitrosothiols, aortic tissue NO, and impaired endothelium-dependent vasorelaxation than wild-type rats. NO reduction was not attributed to differences in endothelial NO synthase (eNOS) protein expression, eNOS-Ser1177 phosphorylation, or tetrahydrobiopterin availability. Aortas from HIV-1 transgenic rats had higher levels of superoxide and 3-nitrotyrosine but did not differ in expression of superoxide-generating sources NADPH oxidase or xanthine oxidase. However, transgenic aortas displayed decreased superoxide dismutase and glutathione. Administering the glutathione precursor procysteine decreased superoxide, restored aortic NO levels and NO-hemoglobin, and improved endothelium-dependent relaxation in HIV-1 transgenic rats. These results show that HIV-1 protein expression decreases NO and causes endothelial dysfunction. Diminished antioxidant capacity increases vascular superoxide levels, which reduce NO bioavailability and promote peroxynitrite generation. Restoring glutathione levels reverses HIV-1 protein-mediated effects on superoxide, NO, and vasorelaxation.

HIV-related cardiovascular disease and drug interactions

HIV infection is a global public health issue that is frequently associated with cardiovascular involvement. These HIV-associated cardiovascular manifestations are often clinically occult or attributed incorrectly to other non-cardiac disease processes. A heightened awareness and routine screening for cardiovascular involvement in HIV-infected patients leads to earlier detection and the hope for a reduction in associated morbidity and mortality. Left ventricular dysfunction, an independent predictor of mortality in HIV-infected patients, is the result of many causes in this population and may result in dilated cardiomyopathy and congestive heart failure in about 10% of patients. Other HIV-associated cardiovascular problems include infective endocarditis, cardiovascular malignancy, pulmonary arterial hypertension, vasculitis, pericardial effusion, premature atherosclerosis, and arrhythmias. HIV-associated cardiovascular emergencies include congestive heart failure, pulmonary edema, supraventricular and ventricular arrhythmias, endocarditis, and tamponade. Anti-infective and immunomodulatory therapies may be particularly helpful in this population to reduce associated cardiovascular disease. Highly active antiretroviral therapy may result in lipodystrophy, hyperlipidemia, truncal adiposity, and insulin resistance that can be improved by physical activity and training programs. Cardiovascular complications of therapeutic drugs in HIV-infected patients include torsade de pointes, congestive heart failure, dyslipidemia, accelerated atherosclerosis, and myocardial infarction. In summary, cardiovascular complications are important contributors to morbidity and mortality in HIV-infected patients that can be detected early in many cases and treated effectively.

Nucleoside reverse transcriptase inhibitors impair endothelium-dependent relaxation by increasing superoxide

Nucleoside reverse transcriptase inhibitors (NRTIs) have been used successfully to reduce acquired immunodeficiency syndrome mortality. However, the use of these compounds is associated with numerous tissue toxicities, including cardiomyopathy. These studies address the effects of NRTIs on vascular function. Functional assays of contraction and relaxation were performed on isolated mouse aorta segments obtained from FVB/n mice exposed to zidovudine (AZT), stavudine, or water for 35 days. AZT and stavudine treatment impaired sensitivity to endothelium-dependent relaxation by acetylcholine. Dihydroethidium staining revealed that AZT treatment was associated with an increase in superoxide levels. Pretreatment of AZT-treated vessels with tiron (1 mM), a free radical scavenger, restored endothelium-dependent relaxation in mice. In cellular preparations, electron spin resonance measurements revealed elevated superoxide in cultured endothelial cells exposed to AZT; elevation was dependent on the length of exposure. These results indicate that NRTIs impair endothelium-dependent relaxation by increasing superoxide levels and suggest that NRTI therapy contributes to cardiovascular complications in acquired immunodeficiency syndrome.