Steroid hormone, cytokine, lipid and metabolic disturbances in HIV infection

Immune Activation, Proinflammatory Cytokines, and Conventional Risks for Cardiovascular Disease in HIV Patients: A Case-Control Study in Bahia, Brazil

Background

Cardiovascular events (CVE) are an increasing cause of morbi-mortality for HIV patients. The antiretroviral therapy (ART), persistent immune activation, and life style are factors that can increase CVE for such patients. We performed a case-control study to evaluate the role of coinfections and immune markers associated with CVE.

Methods

We included patients under ART, with undetectable plasma viral load ≥12 months. Patients presenting any condition of risk for CVE were considered cases, and those without CVE risk conditions were controls. History of viral infections (Epstein-Barr virus, hepatitis C virus, hepatitis B virus, and cytomegalovirus), exposure to antiretroviral drugs, time since HIV diagnosis/under ART, and life style (demographics, weight, smoking, alcohol, and illicit drug use) were assessed. CD4/CD8 nadir and current counts, nadir and current CD4/CD8 ratio, immune activation markers (CD4CD38HLADR, CD8CD38HLADR), and serum levels of eight cytokines [IL-2, IL-4, IL-6, IL-10, tumoral necrosis factor-alpha (TNF-α), interferon gamma, macrophage inflammatory proteins 1 alpha, and interferon-inducing protein (IP-10)] were measured.

Results

Two-thirds of patients were males. Cases (N = 106) were older (52.8 vs 49.5 years, p = 0.002), had higher levels of creatinine (0.97 vs 0.87 mg/dL, p = 0.002) and IL-6 (0.67 vs 0.52 pg/mL, p = 0.04) than controls (N = 114). There was no difference between groups regarding frequency of CD4CD39HLADR+ or CD8CD38HLADR+ cells. We found a significant correlation (all patients) between increased frequency of CD4CD38HLADR+ cells and levels of IP-10 (r = 0.171, p = 0.02) and TNF-α (r = 0.187, p = 0.01). Levels of IL-6 (r = 0.235, p = 0.02), TNF-α (r = 0.267, p = 0.01), and IP-10 (r = 0.205, p = 0.04) were correlated with CD4CD38HLADR+ cells, in controls. Higher frequency of CD4CD38HLADR+ cells was also correlated with levels of IP-10 (r = 0.271, p = 0.04) in patients presenting with arterial hypertension. Frequency of CD4CD38HLADR+ cells was negatively correlated with levels of IL-2 (r = -0.639, p = 0.01) and IL-6 (r = -0.0561, p = 0.03) in patients with hypercholesterolemia. No association was detected between viral infections or smoking/alcohol use and immune activation markers.

Conclusion

Our results indicate IL-6 levels are associated with increased CV risk. Activated CD4+ T cells were associated with increased levels of proinflammatory cytokines.

Inflammation-modulating cytokine profile and lipid interaction in HIV-related risk factors for cardiovascular diseases

HIV infection and antiretroviral therapy (ART) are associated with changes in plasma levels of lipoproteins, thus posing the risk of cardiovascular complications in infected individuals. The alteration in plasma lipoprotein levels results from dysregulation of inflammation-modulating cytokines that control lipid metabolism. Little is understood regarding the relationship between the cytokines and serum lipid levels, which have been reported to be altered in adults receiving ART. The objective of this study was to describe the profiles of inflammation-modulating cytokines and their relationship to lipids as cardiovascular disease (CVD) risk factors in HIV infection. This observational cross-sectional study measured plasma levels of interleukin (IL)-10, tumor necrosis factor-alpha (TNF)-α, IL-4, total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-c) in HIV-infected and uninfected adults. A total of 219 HIV-infected participants were enrolled from an HIV treatment center; of them, 187 were receiving ART and 32 were ART naïve, while 65 were HIV-uninfected blood donors. HIV-infected individuals had higher levels of IL-10 (HIV-infected ART-naïve [P=0.0024] and ART-receiving [P=0.033]) than their uninfected counterparts. ART-naïve subjects had significantly higher plasma levels of IL-10 than ART-receiving subjects (P=0.0014). No significant difference was observed in plasma levels of IL-4 and TNF-α across the three groups. Regarding plasma lipoproteins, HDL-c levels were reduced in HIV ART-naïve (P=0.002) and ART-receiving (P=0.015) subjects compared to HIV-uninfected subjects. Similarly, TC levels were lower in the HIV-infected than in the HIV-uninfected group regardless of whether the patients were undergoing ART or not (P<0.001). IL-10 levels correlated with TC levels in the HIV-uninfected group but not in the HIV-infected groups. Levels of HDL-c were reduced, while IL-10 plasma concentrations were elevated in HIV-infected individuals. A correlation observed in HIV-uninfected individuals between anti-inflammatory cytokine IL-10 and TC was lost in HIV-infected individuals. Clinical significance of these differences needs to be ascertained with respect to HIV-related CVD risk.

Biochemical Manifestation of HIV Lipodystrophy Syndrome

OBJECTIVES

Highly active anti-retroviral therapy (HAART), including protease inhibitors (PI) have led to dramatic improvements in the quality and quantity of life in patients with acquired immunodeficiency syndrome (AIDS). However, a significant number of AIDS patients on HAART develop characteristic changes in body fat redistribution referred to as lipodystrophy syndrome (LDS). Features of LDS include hypertrophy in the neck fat pad (buffalo hump), increased fat in the abdominal region (protease paunch), gynecomastia and loss of fat in the mid-face and extremities.

METHODS

The aim of this paper is to review the current knowledge regarding this syndrome. This article reviews the published investigations on biochemical manifestation of HIV lipodystrophy syndrome.

RESULTS

It is estimated that approximately 64% of patients treated with PI will experience this syndrome. Biochemically, these patients have increased triglycerides (Trig), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and extremely low high-density lipoprotein-cholesterol (HDL-C).

CONCLUSIONS AND PUBLIC HEALTH IMPLICATIONS

It is hoped that awareness of this syndrome would aid in early diagnosis and better patient management, possibly leading to a lower incidence of cardiovascular complications among these patients.

Impaired immune responses in tuberculosis patients are related to weight loss that coexists with an immunoendocrine imbalance

The study's objective was to examine whether factors related to the host status may bear some relation with the profile of the immune response displayed by tuberculosis (TB) patients. The in vitro immune response (antigen-driven lymphoproliferation and cytokine production) and the presence of alcoholism or disease-related factors, like heart and respiratory rates, and weight loss (body mass index, BMI) were investigated in 31 males with active, untreated TB. Compared to 16 age-matched healthy males, TB patients presented depressed lymphoproliferation and increased IL-10 and TGF-beta production. Multivariate analysis indicated that most differences were no longer significant when controlling for the BMI. Immune and endocrine changes coexisting with weight loss, such as circulating levels of TNF-alpha, IFN-gamma, IL-6, cortisol, dehydroepiandrosterone and thyroid hormones, were also analyzed. While pairwise correlations between serum levels of IFN-gamma, T3 or T4 and BMI were not significant, BMI was negatively correlated with IL-6 levels (p < 0.025). In turn, levels of IL-6 correlated positively with cortisol concentrations (p <0.001). Stepwise regression analysis demonstrated that BMI was only associated with IL-6 (r = -0.423, R(2) = 0.18), with the difference remaining significant following adjustment for the other variables. As regards IL-6, BMI, cortisol and IFN-gamma could explain 74% of variability in IL-6 concentrations (R(2) = 0.74). No evidence for effect modification was shown when performing adjusted calculations. To conclude, the relation between weight loss and abnormal immune response of TB patients is partly associated with the immunoendocrine imbalance observed in parallel.

Molecular and cellular mechanisms of neuronal cell death in HIV dementia

The deaths of neurons, astrocytes and endothelial cells have been described in patients with HIV (human immunodeficiency virus) dementia. HIV-1 does not infect neurons; instead, neurotoxic substances shed by infected glia and macrophages can induce a form of programmed cell death called apoptosis in neurons. These neurotoxins include the HIV-1 proteins Tat and gp120, as well as pro-inflammatory cytokines, chemokines, excitotoxins and proteases. In this article we review the evidence for apoptosis of various cell types within the brain of HIV-infected patients, and describe in vitro and in vivo experimental studies that have elucidated the mechanisms by which HIV causes apoptosis of brain cells.

The paradox of improved antiretroviral therapy in HIV: potential for nutritional modulation?

Chronic infection with HIV type 1 is associated with alterations in macronutrient metabolism, specifically elevated plasma lipids, glucose and reduced insulin sensitivity. These alterations are most severe in patients at the later stages of AIDS, indicating a relationship with disease progression. Recently, a metabolic syndrome, termed lipodystrophy, has been described in successfully-treated HIV patients in whom the altered macronutrient metabolism of HIV infection appears to be amplified markedly, with concurrent alterations in adipose tissue patterning. This syndrome presents a paradox, as before the development of highly-active antiretroviral therapy (HAART) the most severe perturbations in metabolism were observed in the sickest patients. Now, the patients that respond well to therapy are showing metabolic perturbations much greater than those seen before. The implications of this syndrome are that, whilst life expectancy may be increased by reducing viral load, there are concomitant increases in the risk of cardiovascular disease, diabetes and pancreatitis within this patient population. The aetiology of the syndrome remains unclear. In a collaborative trial with the Chelsea and Westminster Hospital in London we have used stable-isotope-labelled fatty acids to examine the hypothesis that treatment with HAART causes a delayed clearance of dietary lipid from the circulation, resulting in the retention of lipid within plasma and the downstream changes in insulin and glucose homeostasis. This hypothesis would indicate a role for low-fat diets, exercise and drugs that reduce plasma lipid or insulin resistance, in modulating the response to antiretroviral therapy in HIV infection.

Increased serum interferon alpha in HIV-1 associated lipodystrophy syndrome

BACKGROUND

A syndrome of lipodystrophy (LD) associated with peripheral lipoatrophy and central/visceral adiposity has been reported in HIV-1-infected patients treated by combined antiretroviral therapy (ART). Lipid metabolism is partly regulated by both steroid hormones and cytokines and we have previously reported that dyslipidaemia in LD-positive men is correlated to an increase in cortisol : DHEA ratio (Christeff et al., AIDS 1999;13:2251). In this study we questioned whether it is also related to cytokine perturbations.

MATERIALS AND METHODS

A cross-sectional study was performed on 42 HIV-1-positive men on ART, 27 of whom had symptoms of LD, defined by computed tomography scan. Serum cytokines (IFN-alpha, TNF-alpha, sTNF-RI, sTNF-RII, IL-6, IL-1beta and IL-2) and lipids [cholesterol, triglycerides (TG) and their subclasses], and apolipoproteins (Apo), were determined.

RESULTS

Serum IFN-alpha was markedly increased in LD-positive compared with LD-negative men and controls. IL-6 and TNF-alpha concentrations were also significantly elevated in HIV-positive men compared to controls but the levels of these cytokines did not differ between the two groups of patients. A significant positive correlation was found between accumulation of IFN-alpha and increased levels of cholesterol, TG, VLDL cholesterol, VLDL TG, ApoB and ApoB-ApoA1 ratio. A multivariate forward-performed analysis revealed that IFN-alpha is the best marker for lipid perturbations associated to LD, followed by insulin and cortisol : DHEA ratio.

CONCLUSIONS

This study demonstrates an association between serum IFN-alpha and lipid alterations in LD-positive men. The concomittant action of IFN-alpha and cortisol : DHEA ratio is probably one of the mechanisms responsible for hyperlipidaemia in LD syndrome.

Endocrine and Metabolic Manifestations of HIV Infection and AIDS

Since the first descriptions of acquired immune deficiency syndrome (AIDS) and human immunodeficiency virus (HIV), a great deal of knowledge has been accumulated on how these entities interact with the endocrine system. Recently new information has been received on autoimmune dysregulation causing thyroid abnormalities after highly active antiretroviral therapy (HAART), as well as metabolic dysregulation occurring in the setting of protease inhibitors. We review the pathophysiologic abnormalities of the endocrine systems due to HIV infection as well as the endocrine effects of drugs commonly used in HIV management. The spectrum of endocrine dysfunction associated with HIV is growing and the intensive care physician must be aware of these potentially reversible abnormalities.

Weight gain, improvement in metabolic profile, and CD4 count with insulin administration in an AIDS patient

Malnutrition with muscle wasting, weight loss, and decreased immunogenicity is a hallmark of Acquired Immune Deficiency Syndrome (AIDS). Several anabolic agents have been utilized for retarding or preventing progressive wasting with limited success. However, insulin, with its most effective anabolic properties, has not been tried in an attempt to prevent or reverse cachexia in AIDS or any other wasting disorders. We report here the effect of using subcutaneous (s.c.) daily administration of insulin 0.3 U/kg (BW) for 6 months in a subject with AIDS. We noted a marked weight gain, improvement in metabolic profiles, that is, lowering of triglyceride, liver enzymes, glycohemoglobin concentrations, as well as 24-hour urinary excretion of urea nitrogen, protein, and creatinine suggestive of positive energy balance. Simultaneously, a marked rise in CD4 counts and an improvement in the thyroid hormone profile were also noted. A deterioration in these parameters occurred during the period of insulin withdrawal following completion of the study protocol. Resumption of insulin administration, on patient's request, once again resulted in the marked improvement similar to that noted during the study period. No adverse effects, including hypoglycemic episodes, were noted during either phase of insulin administration. The possibility that insulin administration may improve the wasting associated with AIDS may warrant further evaluation.

Lipids and retroviruses

The role that lipids may play in enveloped viruses is reviewed. Small lipid molecules can influence retrovirus binding to cell receptors, plasma membrane fusion, and transcription. Palmitoylation following myristoylation of viral glycoproteins is required at the transmembrane level for signal transduction as well as for virion budding and maturation. Cholesterol, ether lipids, phospholipids, platelet-activating factor, phosphatidic acids, diacylglycerols, and several analogs and derivatives influence human immunodeficiency virus (HIV) activity; when conjugated with inhibitors of the viral reverse transcriptase (RT) or aspartyl protease these compounds increase drug effectiveness. On the other hand, L-carnitine, in association with the mitochondrial cardiolipins, inhibits myopathy due to continued prescription of drugs [AZT (zidovudine), ddl (didanoside), or ddC (zalcitabine)], and the redox couple of alpha-lipoic-dihydrolipoic acid prevents production of the reactive oxygen species that trigger apoptosis of infected cells, with sphingomyelin breakdown to ceramides. Retroviral infection induces a shift from phospholipid to neutral fat synthesis in host cells, and a long antiviral, i.e., antiprotease, treatment may lead to lipodystrophy. Multitherapy involving lipids and their analogs in association with anti-RT and antiproteases might enhance the inhibition of growth and proliferation of retroviruses.