HIV infection: a model chronic illness for studying wasting diseases

HIV and antiretroviral therapy-related fat alterations

Early in the HIV epidemic, lipodystrophy, characterized by subcutaneous fat loss (lipoatrophy), with or without central fat accumulation (lipohypertrophy), was recognized as a frequent condition among people living with HIV (PLWH) receiving combination antiretroviral therapy. The subsequent identification of thymidine analogue nucleoside reverse transcriptase inhibitors as the cause of lipoatrophy led to the development of newer antiretroviral agents; however, studies have demonstrated continued abnormalities in fat and/or lipid storage in PLWH treated with newer drugs (including integrase inhibitor-based regimens), with fat gain due to restoration to health in antiretroviral therapy-naive PLWH, which is compounded by the rising rates of obesity. The mechanisms of fat alterations in PLWH are complex, multifactorial and not fully understood, although they are known to result in part from the direct effects of HIV proteins and antiretroviral agents on adipocyte health, genetic factors, increased microbial translocation, changes in the adaptive immune milieu after infection, increased tissue inflammation and accelerated fibrosis. Management includes classical lifestyle alterations with a role for pharmacological therapies and surgery in some patients. Continued fat alterations in PLWH will have an important effect on lifespan, healthspan and quality of life as patients age worldwide, highlighting the need to investigate the critical uncertainties regarding pathophysiology, risk factors and management.

Association of pre-treatment nutritional status with change in CD4 count after antiretroviral therapy at 6, 12, and 24 months in Rwandan women

BACKGROUND

Body mass index (BMI) independently predicts mortality in studies of HIV infected patients initiating antiretroviral therapy (ART). We hypothesized that poorer nutritional status would be associated with smaller gains in CD4 count in Rwandan women initiating ART.

METHODS AND FINDINGS

The Rwandan Women's Interassociation Study and Assessment, enrolled 710 ART-naïve HIV-positive and 226 HIV-negative women in 2005 with follow-up every 6 months. The outcome assessed in this study was change in CD4 count at 6, 12, and 24 months after ART initiation. Nutritional status measures taken prior to ART initiation were BMI; height adjusted fat free mass (FFMI); height adjusted fat mass (FMI), and sum of skinfold measurements. 475 women initiated ART. Mean (within 6 months) pre-ART CD4 count was 216 cells/µL. Prior to ART initiation, the mean (±SD) BMI was 21.6 (±3.78) kg/m(2) (18.3% malnourished with BMI<18.5); and among women for whom the following were measured, mean FFMI was 17.10 (±1.76) kg/m(2); FMI 4.7 (±3.5) kg/m(2) and sum of skinfold measurements 4.9 (±2.7) cm. FFMI was significantly associated with a smaller change in CD4 count at 6 months in univariate analysis (-6.7 cells/uL per kg/m(2), p=0.03) only. In multivariate analysis after adjustment for covariates, no nutritional variable was associated with change in CD4 count at any follow up visit.

CONCLUSION

In this cohort of African women initiating ART, no measure of malnutrition prior to ART was consistently associated with change in CD4 count at 6, 12, and 24 months of follow up, suggesting that poorer pre-treatment nutritional status does not prevent an excellent response to ART.

Induction of host chemotactic response by Encephalitozoon spp

Microsporidians are a group of emerging pathogens typically associated with chronic diarrhea in immunocompromised individuals. The number of reports of infections with these organisms and the disseminated pathology is growing as diagnostic tools become more readily available. However, little is known about the innate immune response induced by and generated against these parasites. Using a coculture chemotaxis system, primary human macrophages were infected with Encephalitozoon cuniculi or Encephalitozoon intestinalis, and the recruitment of naïve monocytes was monitored. Encephalitozoon spp. induced an average threefold increase in migration of naïve cells 48 h postinfection, which corresponded to optimal infection of monocyte-derived-macrophages. A limited microarray analysis of infected macrophages revealed several chemokines involved in the inflammatory responses whose expression was upregulated, including CCL1, CCL2, CCL3, CCL4, CCL7, CCL15, CCL20, CXCL1, CXCL2, CXCL3, CXCL5, and CXCL8. The levels of 6 of 11 chemokines also present in the microarray were confirmed to be elevated by protein profiling. Kinetic studies confirmed that secreted CCL2, CCL3, and CCL4 were expressed as early as 6 h postinfection, with peak expression at 12 to 24 h and expression remaining until 48 h postinfection. Neutralization of these chemokines, specifically CCL4, significantly reduced the number of migrating cells in vitro, indicating their role in the induction of monocyte migration. This mechanism of recruitment not only supports the evidence that in vivo cellular infiltration occurs but also provides new hosts for the parasites, which escape macrophages by rupturing the host cell. To our knowledge, this is the first documentation that chemokine production is induced by microsporidian infections in human macrophages.

Increased adrenal androgen secretion with inhibition of 11beta-hydroxylase in HIV-infected women

Adrenal androgen production is reduced in association with disease severity in HIV-infected women. This response may be maladaptive in terms of maintenance of lean body mass, functional status, and immune function. The aim of this study was to assess whether the use of an adrenal enzyme inhibitor of 11beta-hydroxylase might increase androgen production in this population. We conducted a randomized, double-blind, placebo-controlled study of metyrapone (500 mg p.o. qid) or placebo for 2 wk in 10 HIV-infected women with AIDS wasting [weight <90% ideal body weight (IBW) or weight loss >10%] and reduced androgen levels. Basal and ACTH-stimulated androgen, mineralocorticoid, and glucocorticoid levels were measured at baseline and after 14 days of treatment. Subjects were similar in age (40.9 +/- 0.9 yr), weight (91.7 +/- 3.5% IBW) and hormone concentrations at study entry. Total testosterone (84 +/- 54 vs. -0.4 +/- 2 ng/dl, P = 0.024), free testosterone (6.5 +/- 2.8 vs. 0.1 +/- 0.1 pg/ml, P = 0.024), DHEA (5.0 +/- 3.2 vs. -0.6 +/- 0.5 microg/l, P = 0.024), and 11-deoxycortisol (2,145 +/- 820 vs. -14 +/- 22 ng/dl, P = 0.024) levels increased in response to metyrapone compared with placebo treatment. In response to ACTH, significant increases in the DHEA/cortisol ratio (174 +/- 48 vs. 3 +/- 3, P = 0.008) were seen in the metyrapone group compared with placebo. Blood pressure and electrolytes did not change, and signs of adrenal insufficiency were not apparent. These data demonstrate that inhibition of 11beta-hydroxylase with metyrapone increases adrenal androgen secretion in HIV-infected women. Further studies are needed to assess the physiological effects of this strategy to increase anabolic hormone levels in severe stress, including detailed testing to rule out the potential risk of concomitant adrenal insufficiency.

Nutrient partitioning during treatment of tuberculosis: gain in body fat mass but not in protein mass

BACKGROUND

Tuberculosis is an important cause of wasting. The functional consequences of wasting and recovery may depend on the distribution of lost and gained nutrient stores between protein and fat masses.

OBJECTIVE

The goal was to study nutrient partitioning, ie, the proportion of weight change attributable to changes in fat mass (FM) versus protein mass (PM), during antimycobacterial treatment.

DESIGN

Body-composition measures were made of 21 men and 9 women with pulmonary tuberculosis at baseline and after 1 and 6 mo of treatment. All subjects underwent dual-energy X-ray absorptiometry and deuterium bromide dilution tests, and a four-compartment model of FM, total body water (TBW), bone minerals (BM), and PM was derived. The ratio of PM to FM at any time was expressed as the energy content (p-ratio). Changes in the p-ratio were related to disease severity as measured by radiologic criteria.

RESULTS

Patients gained 10% in body weight (P < 0.001) from baseline to month 6. This was mainly due to a 44% gain in FM (P < 0.001); PM, BM, and TBW did not change significantly. Results were similar in men and women. The p-ratio decreased from baseline to month 1 and then fell further by month 6. Radiologic disease severity was not correlated with changes in the p-ratio.

CONCLUSIONS

Microbiological cure of tuberculosis does not restore PM within 6 mo, despite a strong anabolic response. Change in the p-ratio is a suitable parameter for use in studying the effect of disease on body composition because it allows transformation of such effects into a normal distribution across a wide range of baseline proportion between fat and protein mass.

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.

Beneficial effects of protease inhibitors on body composition and energy expenditure: a comparison between HIV-infected and AIDS patients

OBJECTIVES

(i) To investigate whether protease inhibitor (PI) (nelfinavir)-containing highly active antiretroviral therapy (HAART) affects body composition differently in HIV-infected and AIDS patients without wasting syndrome. (ii) To delineate the changes in resting energy expenditure (REE) under PI therapy, and to determine whether sustained reductions in HIV RNA would decrease REE.

DESIGN

Prospective longitudinal cohort study with individually matched healthy controls.

SETTING

Tertiary care centre at a University Hospital.

METHODS

HIV-seropositive (n = 20) and AIDS patients (n = 17) with a plasma viral load of at least 10000 copies/ml and 37 healthy volunteers were enrolled. All participants were weight stable, free of acute opportunistic infections, and naive to PI therapy. Patients underwent testing of bioelectrical impedance analysis (BIA), indirect calorimetry and food intake, shortly before the initiation of HAART and 24 weeks thereafter.

RESULTS

Both patient groups gained weight, body mass index (BMI), and fat-free mass (FFM) (P < 0.05 versus baseline), whereas only AIDS patients gained fat mass. Increases were more pronounced in the AIDS group. REE was elevated compared with corresponding controls at baseline, and decreased similarly in HIV and in AIDS patients during PI therapy (P < 0.05). The reduction in the viral burden preceded the decrease in REE by several weeks.

CONCLUSION

Body composition and metabolic parameters improved during PI therapy in HIV-infected and AIDS patients without wasting. Although an early reduction in viral load as a result of HAART does not seem to influence REE directly, sustained viral load suppression may promote a decrease in energy expenditure.

HIV disease treatment in the era of HAART

In the last three years basic science and clinical research have radically changed the therapeutical approach to HIV disease. Recent guidelines suggest that treatments to HIV disease should be early and aggressive, with the use of new potent antiretroviral drugs. This approach has been defined as HAART (highly active antiretroviral therapy). In this review we will discuss the main stages of antiretroviral therapy focusing on the acquisitions about results as well as problems of triple therapy.