HIV-1 infection alters gene expression in adipose tissue, which contributes to HIV- 1/HAART-associated lipodystrophy

BACKGROUND: The aetiopathogenic bases of HIV-l-/highly active antiretroviral treatment (HAART)-associated lipodystrophy (HALS) are poorly known, but this syndrome indicates that adipose tissue is highly sensitive to either HIV-1 infection, antiretroviral drugs or their combination. METHODS: To assess the relative contribution of infection and drugs, we compared the expression of marker genes corresponding to mitochondrial function, adipocyte differentiation and metabolism, and adipokines in subcutaneous adipose tissue from healthy controls, untreated HIV-1-infected patients, and HIV-1-infected patients treated with HAART with or without HALS. RESULTS: Subcutaneous adipose tissue from HIV-1-infected patients contained lower concentrations of the mRNA of the mitochondrial DNA-encoded cytochrome c oxidase subunit II than that of controls. These concentrations decreased further in association with HAART. The expression of nuclear genes coding for mitochondrial proteins, peroxisome proliferator-activated receptor-y, and adipocyte-specific markers was reduced in HIV-1-infected patients, treated or not, with respect to the controls. In contrast, the mRNA concentrations of uncoupling protein-3 and preadipocyte factor-1 increased in lipody-strophic HAART-treated patients. The genes coding for adipokines were strongly affected: tumour necrosis factor-alpha was upregulated, whereas adiponectin and leptin were downregulated in HIV-1-infected patients, treated or not. Thus, substantial alterations of gene expression were already present when naive patients were compared with controls. Further changes were associated with HAART and with the diagnosis of HALS. CONCLUSIONS: Disturbances in adipose tissue gene expression are already present in untreated HIV-1-infected patients, thus indicating a role of HIV-1 infection itself in eliciting adipose tissue alterations that are worsened by HAART, which ultimately leads to HALS.     

Cerebrospinal fluid viral loads reach less than 2 copies/ml in HIV-1-infected patients with effective antiretroviral therapy

BACKGROUND: A low-grade persisting viraemia despite long-term treatment with highly active antiretroviral therapy (HAART) has previously been demonstrated in HIV-1-infected patients. Whether ongoing viral replication also could be detected in cerebrospinal fluid (CSF) in those circumstances has not been studied before. METHODS: Paired CSF and blood samples from 13 neurologically asymptomatic HIV-1-infected patients on stable HAART were analysed regarding HIV-1 RNA, by using a PCR assay with a detection limit of 2 copies/ml. RESULTS: All 13 patients had HIV-1 RNA < 2 copies/ml in CSF, compared with 8/13 in plasma. CONCLUSION: We could not demonstrate any persistent viral replication in the CSF of neurologically asymptomatic HIV-1-infected patients on effective HAART, rendering it unlikely that CSF acts as a viral reservoir in this category of patients.     

Tumour necrosis factor alpha in fat redistribution syndromes associated with combination antiretroviral therapy in HIV-1-infected patients: potential role in subcutaneous adipocyte apoptosis

BACKGROUND: The pathogenesis of fat redistribution syndromes (FRS) observed in the setting of highly active antiretroviral therapy (HAART) for the treatment of HIV-1-infection remains elusive. A dysregulation of the tumour necrosis factor alpha (TNF-alpha) system occurs in HIV-infected patients with FRS. MATERIALS AND METHODS: The study looked at both the in vivo and in vitro relationship between TNF-alpha and the degree of subcutaneous adipocyte apoptosis in 60 HIV-1-infected patients on HAART with FRS, another 60 HIV-1-infected patients on HAART without FRS and 60 uninfected control patients. Apoptosis was assessed by the terminal deoxynucleotidyl transferase dUTP (deoxyuridine 5'-triphosphate)-digoxigenin Nick End Labelling (TUNEL) method. Soluble receptors of TNF-alpha were determined by the sandwich enzyme immunoassay technique. The in vitro viability was assessed by staining with 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) and apoptosis by TUNEL. RESULTS: HIV-1-infected patients with FRS had significantly higher degrees of subcutaneous adipocyte apoptosis than those without FRS (P = 0.0001) and uninfected controls (P < 0.0001). There was a statistically significant association between serum levels of soluble TNF-alpha receptors #1 and #2 and the degree of subcutaneous adipocyte apoptosis in patients with and without FRS (P < 0.0001 for both receptors). In vitro, the addition of TNF-alpha (10 ng mL(-1)) to an adipocyte culture embedded with indinavir, either alone or in clinically relevant combinations with stavudine (d4T) and lamivudine (3TC), significantly decreased adipocyte viability (P = 0.0001) and increased adipocyte apoptosis (P < 0.0001) with respect to that observed with the addition of antiretrovirals alone. CONCLUSIONS: TNF-alpha plays a significant role in subcutaneous adipocyte apoptosis, which occurs in the setting of FRS in HIV-1-infected patients on highly active antiretroviral therapy.     

Prdm16 determines the thermogenic program of subcutaneous white adipose tissue in mice

The white adipose organ is composed of both subcutaneous and several intra-abdominal depots. Excess abdominal adiposity is a major risk factor for metabolic disease in rodents and humans, while expansion of subcutaneous fat does not carry the same risks. Brown adipose produces heat as a defense against hypothermia and obesity, and the appearance of brown-like adipocytes within white adipose tissue depots is associated with improved metabolic phenotypes. Thus, understanding the differences in cell biology and function of these different adipose cell types and depots may be critical to the development of new therapies for metabolic disease. Here, we found that Prdm16, a brown adipose determination factor, is selectively expressed in subcutaneous white adipocytes relative to other white fat depots in mice. Transgenic expression of Prdm16 in fat tissue robustly induced the development of brown-like adipocytes in subcutaneous, but not epididymal, adipose depots. Prdm16 transgenic mice displayed increased energy expenditure, limited weight gain, and improved glucose tolerance in response to a high-fat diet. shRNA-mediated depletion of Prdm16 in isolated subcutaneous adipocytes caused a sharp decrease in the expression of thermogenic genes and a reduction in uncoupled cellular respiration. Finally, Prdm16 haploinsufficiency reduced the brown fat phenotype in white adipose tissue stimulated by β-adrenergic agonists. These results demonstrate that Prdm16 is a cell-autonomous determinant of a brown fat-like gene program and thermogenesis in subcutaneous adipose tissues.     

HIV-1–specific immune responses in subjects who temporarily contain virus replication after discontinuation of highly active antiretroviral therapy

Therapeutic intervention with highly active antiretroviral therapy (HAART) can lead to suppression of HIV-1 plasma viremia to undetectable levels for 3 or more years. However, adherence to complex drug regimens can prove problematic, and subjects may temporarily discontinue HAART for variable periods. We studied 6 HIV-1-infected individuals who stopped therapy. Off HAART, levels of viremia were suppressed to fewer than 500 copies/mL in 2 subjects for more than 12 and more than 24 months, respectively, and in 1 subject for 4 months on 1 occasion. Three subjects failed to contain plasma viremia. Broad and strong HIV-1-specific immune responses were detected in subjects with prolonged suppression of viral replication. This longitudinal study suggests that containment of HIV-1 replication to low or undetectable levels after discontinuation of HAART is associated with strong virus-specific immune responses. Boosting of HIV-1-specific immune responses should be considered as an adjunctive treatment strategy for HIV-1-infected individuals on HAART.     

腹部和大腿皮下脂肪组织抵抗素蛋白的表达

背景:抵抗素是脂肪细胞分泌的一种多肽激素。而中心性肥胖时可引起胰岛素抵抗和导致2型糖尿病。目的:比较正常人腹部和大腿皮下脂肪组织抵抗素蛋白表达的情况,探讨抵抗素在中心性肥胖引起胰岛素抵抗中的作用。设计:对照观察实验。单位:华中科技大学同济医学院附属同济医院内分泌科。对象:选择2003-01/04华中科技大学同济医学院附属同济医院外科住院患者20例,根据留取脂肪组织的部位分腹部皮下脂肪组织组12例和大腿皮下脂肪组织组8例。方法:①所有患者测量血压、身高、体质量,计算体质量指数,体内脂肪百分比(按白种人数据推导的公式):男性=1.2×体质量(kg) 身高-2(m-2) 0.23×年龄-16.2;女性=1.2×体质量(kg) 身高-2(m-2) 0.23×年龄-5.4。②葡萄糖氧化酶法测定空腹血糖。③留取的脂肪组织标本用单去污裂解液提取脂肪组织中的蛋白质,考马斯亮蓝法测定蛋白质浓度,Western-blot测量脂肪组织抵抗素蛋白的表达水平。主要观察指标:两组患者的血压、体质量指数,体内脂肪百分比,空腹血糖,抵抗素蛋白的表达水平。结果:纳入患者20例,均进入结果分析。①两组的空腹血糖、收缩压、舒张压、体质量指数、体内脂肪百分比差异无显著性(P>0.05)。②腹部皮下脂肪组织抵抗素蛋白表达(A)为14942±6076,明显高于大腿皮下脂肪组织组39421±6087,二者比较差异显著(P<0.01)。结论:抵抗素蛋白在腹部皮下脂肪组织的表达高于腿部皮下脂肪组织,此结果对中心性肥胖并引起胰岛素抵抗和2型糖尿病的发生具有参考价值。     

Surgical implantation of adipose tissue reverses diabetes in lipoatrophic mice

In lipoatrophic diabetes, a lack of fat is associated with insulin resistance and hyperglycemia. This is in striking contrast to the usual association of diabetes with obesity. To understand the underlying mechanisms, we transplanted adipose tissue into A-ZIP/F-1 mice, which have a severe form of lipoatrophic diabetes. Transplantation of wild-type fat reversed the hyperglycemia, dramatically lowered insulin levels, and improved muscle insulin sensitivity, demonstrating that the diabetes in A-ZIP/F-1 mice is caused by the lack of adipose tissue. All aspects of the A-ZIP/F-1 phenotype including hyperphagia, hepatic steatosis, and somatomegaly were either partially or completely reversed. However, the improvement in triglyceride and FFA levels was modest. Donor fat taken from parametrial and subcutaneous sites was equally effective in reversing the phenotype. The beneficial effects of transplantation were dose dependent and required near-physiological amounts of transplanted fat. Transplantation of genetically modified fat into A-ZIP/F-1 mice is a new and powerful technique for studying adipose physiology and the metabolic and endocrine communication between adipose tissue and the rest of the body.     

Studies of Human Adipose Tissue ADIPOSE CELL SIZE AND NUMBER IN NONOBESE AND OBESE PATIENTS

The cellular character of the adipose tissue of 21 nonobese and 78 obese patients has been examined. Adipose cell size (lipid per cell) was determined in three different subcutaneous and deep fat depots in each patient and the total number of adipose cells in the body estimated by division of total body fat by various combinations of the adipose cell sizes at six different sites. Cell number has also been estimated on the basis of various assumed distribution of total fat between the subcutaneous and deep fat depots.Obese patients, as a group, have larger adipose cells than do nonobese patients; cell size, however, varies considerably among the fat depots of individuals of either group. The variation in cell size exists not only between, but also within subcutaneous and deep sites. Estimates of total adipose cell number for a given individual based upon cell size can, therefore, vary by as much as 85%. On the basis of these studies it is suggested that the total adipose number of an individual is best and most practically estimated, at this time, by division of total body fat by the mean of the adipose cell sizes of at least three subcutaneous sites.IRRESPECTIVE OF THE METHOD BY WHICH TOTAL ADIPOSE CELL NUMBER IS ESTIMATED, TWO PATTERNS OF OBESITY EMERGE WITH RESPECT TO THE CELLULAR CHARACTER OF THE ADIPOSE TISSUE MASS OF THESE PATIENTS: hyperplastic, with increased adipose cell number and normal or increased size, and hypertrophic, with increased cell size alone. These two cellular patterns of obesity are independent of a variety of assumed distributions of fat among the subcutaneous and deep depots. When these different cellular patterns are examined in terms of various aspects of body size, body composition, and the degree, duration, and age of onset of obesity, only the latter uniquely distinguishes the hyperplastic from the hypertrophic: hyperplastic obesity is characterized by an early age of onset, hypertrophic, by a late age of onset. These studies indicate that there are two distinct periods early in life during which hypercellularity of the adipose tissue are most likely to occur: very early within the first few years, and again from age 9 to 13 yr.     

Efficiency of white cell filtration and a freeze-thaw procedure for removal of HIV-infected cells from blood

Strategies for diminishing the risk of blood transfusion-associated transmission of HIV-1 were evaluated. HIV-1-infected peripheral blood mononuclear cells were added to blood that was subsequently filtered by using different white cell (WBC) filters (cellulose acetate and polyester). The average log reduction of infected cells with polyester filters was at least 2.5 as measured by ID50 titration and polymerase chain reaction. In two WBC filtration experiments with blood from seropositive donors diluted 1:4 with seronegative blood, log reductions of 2.4 and greater than 2.5 were observed. No cell-free virus was retained by the filter used. A freeze-thaw procedure applied to HIV-1-contaminated blood resulted in a minimal log reduction. These results indicate that the reduction of HIV-1 infectivity as a result of filtration is mainly due to the removal of HIV-1-infected WBCs, and that complete removal of infected WBCs cannot be achieved by the current filtration or freeze-thaw procedures. However, the development of filters with enhanced ability to remove (possibly infected) WBCs may have the added benefit of improving the safety of donor blood, especially in multiply transfused patients.     

Enhanced expression of the CXCR4 co-receptor in HIV-1-infected individuals correlates with the emergence of syncytia-inducing strains

The aim of this study was to investigate the mechanisms responsible for the emergence in some HIV-1-infected individuals of highly aggressive, syncytia-inducing (SI) HIV-1 strains, which have been shown to use CXCR4 as co-receptor to enter target cells. To this end, the percentages of circulating CXCR4+CD4+ T cells were evaluated by flow cytometry in 39 untreated and 61 highly active antiretroviral therapy (HAART)-treated HIV-1-infected individuals in comparison with 35 HIV-1 seronegative subjects. Plasma viremia was also measured, and HIV primary isolates, from both untreated and HAART-treated HIV-1-infected subjects, were tested for the presence of SI strains. The results of this study showed enhanced proportions of CXCR4+CD4+ T cells in untreated patients in comparison with HAART-treated and healthy subjects. Furthermore, the results of a 12-month longitudinal study in a cohort of 11 patients undergoing HAART showed a significant reduction of CXCR4 expression after successful therapy. Finally, a significant positive correlation among the proportions of circulating CXCR4-expressing CD4+ T cells, plasma viremia, and the probability to isolate SI strains was found. These in vivo data are in keeping with previous in vitro results suggesting a bidirectional link between HIV-1 and CXCR4 expression on CD4+ T cells, and provide some clues to understanding the mechanisms exerting a selective pressure toward the emergence of SI strains.     

Highly active antiretroviral therapy versus zidovudine/nevirapine effects on early breast milk HIV type-1 Rna: a phase II randomized clinical trial

BACKGROUND: Defining the effect of antiretroviral regimens on breast milk HIV type-1 (HIV-1) levels is useful to inform the rational design of strategies to decrease perinatal HIV-1 transmission. METHODS: Pregnant HIV-1 seropositive women (CD4+ T-cell count >250 and <500 cells/mm3) electing to breastfeed in Nairobi, Kenya were randomized to highly active antiretroviral therapy (HAART; zidovudine [ZDV], lamivudine and nevirapine [NVP]) during pregnancy and 6 months post-partum or to short-course ZDV plus single-dose NVP (ZDV/NVP). Breast milk samples were collected two to three times per week in the first month post-partum. RESULTS: Between November 2003 and April 2006, 444 breast milk samples were collected from 58 randomized women during the first month after delivery. Between 3 and 14 days post-partum, women in the HAART and ZDV/NVP arms had a similar prevalence of undetectable breast milk HIV-1 RNA. From 15 to 28 days post-partum, women in the HAART arm had significantly lower levels of breast milk HIV-1 RNA than women randomized to ZDV/NVP (1.7 log10 copies/ml [limit of detection] versus >2.10 log10 copies/ml, P<0.001). In contrast to breast milk HIV-1 RNA, suppression of plasma HIV-1 RNA during the neonatal period was consistently several log10 greater in the HAART arm compared with the ZDV/NVP arm. CONCLUSIONS: HAART resulted in lower breast milk HIV-1 RNA than ZDV/NVP; however, ZDV/NVP yielded comparable breast milk HIV-1 RNA levels in the first 2 weeks post-partum. Breast milk HIV-1 RNA remained suppressed in the ZDV/NVP arm despite increased plasma HIV-1 levels, which might reflect local drug effects or compartmentalization.     

Spontaneous apoptosis and highly active antiretroviral therapy (HAART).

Increased programmed cell death (PCD) or apoptosis has been detected in the T cells of HIV-infected subjects; it is held partially responsible for the continuous loss of CD4+ T cells during the natural course of HIV infection. Highly active antiretroviral therapy (HAART) decreases the viral load and leads to an increase of CD4+ count in vivo. In this study we evaluated PCD in total peripheral blood mononuclear cells, CD8+ and CD4+ lymphocytes before and four weeks after initiation of HAART. Seven HIV-1-infected patients were investigated. Viral load was assessed by RT-polymerase chain reaction and PCD by flow cytometry using apoptosis by 7 amino actinomycin D (7AAD) and propidium iodide (PI). After four weeks of HAART, CD4+ T and CD8+ T cell levels were stable, and plasma HIV-RNA copies were significantly decreased. In four of the patients (4/7), HIV-RNA levels were reduced to undetectable levels (fewer than 400 copies per milliliter). A statistically significant reduction of apoptosis among CD4+ cells was observed (P < 0.03), though neither in the CD8+ T cell population nor in peripheral blood mononuclear cells (PBMCS). These results demonstrate the beneficial effect of HAART on apoptosis of CD4+ cells in the early treatment stage.     

Detection of HIV-1 infections by PCR: evaluation in a seropositive subject population

To study the polymerase chain reaction (PCR) performance in detecting human immunodeficiency virus (HIV) infections, we tested 53 HIV-1 seropositive patients and 29 HIV-1 seronegative subjects for four different HIV-1 DNA regions. Fifty-one seropositive patients were found positive by PCR with at least one primer pair, but two were repeatedly negative for all primers. Weekly blood samples from 12 seropositive subjects all detected positive for at least one primer pair, but for three patients an irregular primer detection pattern was found. One additional HIV-1 seropositive sample, found negative for HIV DNA, was also negative for the beta-globin PCR control. The 29 seronegative specimens were HIV-1 DNA negative, as was a HIV-2 seropositive patient. This study demonstrates that PCR is almost as good as serological tests for detecting HIV infections, with a specificity of 100% and a sensitivity of 96% and that resampling the patients may improve detection performance.     

Risk for HIV-1 infection is not associated with repeat-region polymorphism in the DC-SIGN neck domain and novel genetic DC-SIGN variants among North Indians

BACKGROUND: Several genetic factors have been related to HIV-1 resistance, the homozygosity for a mutation in CCR5 gene (CCR5Delta 32 allele) is presently considered the most relevant one. The C-type lectin, DC-SIGN efficiently binds and transmits HIV-1 to susceptible cell in trans thereby augmenting the infection. A potential association of the DC-SIGN neck domain repeats polymorphism and risk of HIV-1 infection is currently under debate. METHODS: Genetic risk association study was conducted in HIV-1 exposed seronegative (HES; n=50) individuals, HIV-1 seronegative (HSN; n=314) healthy control and HIV-1 infected seropositive patients (HSP; n=190) for polymorphism in neck domain of DC-SIGN gene. The DC-SIGN genotypes were identified by PCR from DNA extracted from peripheral blood and confirmed by sequencing. Fisher exact or chi(2) test was used for statistical analysis. RESULTS: One HSN and HSP individual who were heterozygous (7/8) with respect to DC-SIGN repeat regions were found. The DC-SIGN neck repeat polymorphism among North Indian individuals was not associated with susceptibility to HIV-1 infection. Furthermore, inheritance study of heterozygous mutation (7/8) in HSN individual's family showed that one parent, two brothers, one sister and one daughter were heterozygous (7/8) for DC-SIGN mutant allele. Sequence analyses of DC-SIGN exon 4 repeat region of randomly selected 25 North Indian individuals from HSP, HSN and HES revealed four conserved intronic mutations. These mutations were at nucleotide position 1283, 1306, 1308 upstream and 1906 downstream of the DC-SIGN exon 4 repeat region when compared with the wild type sequence (NCBI Acc. No. AF209479). CONCLUSION: The polymorphism in DC-SIGN neck repeats region was rare and not associated with HIV-1 susceptibility among North Indians. Sequencing analysis of DC-SIGN gene confirmed four novel genetic variants in intronic region flanking exon 4 coding region.