Adipogenic gene variants in patients with HIV-associated lipodystrophy.

OBJECTIVES: Although highly active antiretroviral therapy (HAART) has been hugely beneficial in the treatment of HIV, HIV lipodystrophy (HIVLD) associated with HAART is a serious adverse effect, with long-term consequences including metabolic disturbances and an increased risk of atherosclerotic disease. Although HIVLD is clearly related to the drug regimen, individual susceptibility also plays a role. We hypothesized that variation in genes regulating adipogenesis, and in those implicated in inherited forms of lipodystrophy, may predispose to the development of HIVLD. METHODS: DNA samples were obtained from 180 HAART-treatedHIV+ patients: 124 with HIVLD (HIVLD+) and 56 without HIVLD (HIVLD-). Diagnosis of HIVLD was carried out by clinician's confirmation of patient self-report. High-throughput genotyping using Sequenom was used to screen 62 single nucleotide polymorphisms (SNPs) in eight genes involved in adipogenesis and inherited forms of lipodystrophy. Statistical analysis was performed using Haploview. Multivariate analysis (logistic regression) was used to identify independent predictors of HIVLD development in HAART-treated patients. RESULTS: SNPs in two adipogenesis regulators, LPIN1 and CEBPα, showed a significant association with HIVLD whereas a SNP in ZMPSTE24, a zinc metalloproteinase involved in prelamin A processing, showed a trend toward significance. Multivariate analysis identified time since HIV diagnosis (P=0.001) and carriage of more than one associated allele (P=0.008) to be the most significant independent predictors for the development of HIVLD. CONCLUSION: Genetic variation in key regulators of adipogenesis could interfere with fat storage and metabolism contributing to the development of HIVLD in HAART-treated HIV patients. These results need replication in other cohorts.

Reduction in neutrophil count during hepatitis C treatment: drug toxicity or predictor of good response?

BACKGROUND: Bone marrow suppression is a well-recognized toxicity of the treatment of hepatitis C virus (HCV). Reduction of the peginterferon dose because of neutropenia is common in clinical practice. However, reduction of peginterferon dose during the first weeks of HCV treatment is associated with failure to achieve sustained virological response. AIMS: The objective of this study is to investigate whether the fall of neutrophil count during hepatitis C treatment is associated with achieving sustained virological response. METHODS: We performed an observational study of patients who completed peginterferon and ribavirin treatment in an Infectious Diseases Department in Manchester, UK. RESULTS: Of the 74 patients included in the analysis, 78% had genotype 2 or 3 hepatitis C and 15% had liver cirrhosis. Sustained virological response was achieved in 78% of patients. On univariate analysis, factors related to achieving sustained virological response were younger age, genotype 2 or 3, baseline neutrophil count, and fall of neutrophil count during treatment. Multivariate analysis showed baseline neutrophil count >3.5 x 10(3) cells/mm(3) [odds ratio (OR) 5.7; 95% confidence interval (CI) 1.24-26.3] and a reduction of neutrophil count >60% (OR 4.5; 95% CI 1.03-19.9) to be independently associated with achieving sustained virological response. Neutropenia was not associated with an increased risk of infections. CONCLUSIONS: In this observational study, higher baseline neutrophil count and fall of neutrophil count during the treatment of hepatitis C was associated with achieving sustained virological response. These findings could have important implications for the monitoring and management of HCV treatment with peginterferon if they are confirmed in other studies.

TNF, LTA, HSPA1L and HLA-DR gene polymorphisms in HIV-positive patients with hypersensitivity to cotrimoxazole.

AIMS: Sulfamethoxazole in combination with trimethoprim (cotrimoxazole) is used for prophylaxis and treatment of several opportunistic infections in HIV-infected patients. It is associated with a high incidence of hypersensitivity reactions, which is thought to have an immune basis. Genetic polymorphisms in MHC are known to predispose to hypersensitivity reactions to a structurally diverse group of drugs in HIV-positive patients. The aim of the study was to determine whether functional polymorphisms in TNF, LTA, HSPA1L and HLA-DRB1 genes influence the risk of cotrimoxazole hypersensitivity in HIV-infected patients. METHODS: We genotyped 136 HIV-positive patients with (n = 53) and without (n = 83) cotrimoxazole hypersensitivity using a combination of PCR-based techniques, including PCR-restriction fragment length polymorphisms, PCR-sequence specific oligonucleotides and real-time PCR. Genotypes and the haplotype frequencies were analyzed using the chi(2) test in the Haploview and CLUMP programs. RESULTS: No statistically significant difference in SNP or haplotype frequencies were found in HIV-infected sulfamethoxazole hypersensitive patients compared with controls. CONCLUSION: Our data show that MHC polymorphisms are not major predisposing factors for cotrimoxazole hypersensitivity, although we cannot exclude a minor contribution. An environmental factor (i.e., HIV infection) seems to predominate over any of the genetic factors so far investigated in increasing the risk of cotrimoxazole hypersensitivity.

Immune reconstitution associated with progressive multifocal leukoencephalopathy in human immunodeficiency virus: a case discussion and review of the literature.

OBJECTIVES: To report the neuropathological findings of a patient with immune reconstitution syndrome associated with progressive multifocal leukoencephalopathy (PML) in human immunodeficiency virus (HIV) and to review the literature. METHODS: A 38-year-old man was presented with a rapidly evolving brainstem syndrome. Serology for HIV was positive with an initial CD4 count of 130 cells/mL3. Magnetic resonance imaging showed widespread high signal changes within the brainstem bilaterally, the cerebellum, inferior cerebellar peduncle, and the frontal lobe on the right. Opportunistic infections were excluded from blood and cerebrospinal fluid samples. Despite treatment with antiretrovirals, he continued to deteriorate neurologically, and a repeat magnetic resonance imaging scan showed progression of his lesions. Cortical wedge frontal lobe brain biopsy showed features characteristic of PML, but was associated with an exaggerated inflammatory response. Polymerase chain reaction analysis of the specimen demonstrated the presence of JC virus (JCV) DNA, confirming the pathologic impression of PML. RESULTS: The patient made a rapid (within 24 hours) improvement with pulsed methylprednisolone and has maintained a clinical response 7 months later. These features clinically, radiologically, and histopathologically suggest an added component in the form of immune reconstitution syndrome to PML. CONCLUSION: This report highlights the need to carefully evaluate the clinical syndrome in patients with HIV-associated leukoencephalopathy. It also substantiates the role of corticosteroids in carefully considered cases of HIV with leukoencephalopathy secondary to immune reconstitution.

Drug-specific T cells in an HIV-positive patient with nevirapine-induced hepatitis.

BACKGROUND: Nevirapine is associated with idiosyncratic reactions such as skin rash, hepatitis and hypersensitivity syndrome, which have the hallmarks of being immune mediated. However, there is little laboratory evidence to support an immune pathogenesis. METHODS: A HIV-positive individual who developed hepatitis within 6 weeks of starting nevirapine, in the absence of any cutaneous manifestations, is described. Other causes of hepatitis were excluded, and the patients liver function normalized on withdrawal of nevirapine. Lymphocytes from the patient, and six individuals with HIV who were on nevirapine without adverse effects, were exposed to nevirapine and its metabolites, and lymphocyte proliferation assessed by 3H-thymidine incorporation on day 5. RESULTS: The T cells taken from the nevirapine-hypersensitive patient proliferated in the presence of nevirapine with a stimulation index of greater than 2. There was no proliferation with nevirapine metabolites. T cells taken from HIV-positive control individuals showed no proliferation with either nevirapine or its metabolites. CONCLUSION: The results from our patient suggest that T cells may be involved in the pathogenesis of nevirapine-induced hepatitis. Larger numbers of patients need to be studied to fully evaluate the role of T cells in nevirapine-induced hepatitis and nevirapine hypersensitivity syndrome.

Cost-effectiveness analysis of HLA B*5701 genotyping in preventing abacavir hypersensitivity.

OBJECTIVE: Abacavir, a human immunodeficiency virus-1 (HIV-1) nucleoside-analogue reverse transcriptase inhibitor, causes severe hypersensitivity in 4-8% of patients. HLA B*5701 is a known genetic risk factor for abacavir hypersensitivity in Caucasians. Our aim was to confirm the presence of this genetic factor in our patients, and to determine whether genotyping for HLA B*5701 would be a cost-effective use of healthcare resources. METHODS: Patients with and without abacavir hypersensitivity were identified from a UK HIV clinic. Patients were genotyped for HLA B*5701, and pooled data used for calculation of test characteristics. The cost-effectiveness analysis incorporated the cost of testing, cost of treating abacavir hypersensitivity, and the cost and selection of alternative antiretroviral regimens. A probabilistic decision analytic model (comparing testing versus no testing) was formulated and Monte Carlo simulations performed. RESULTS: Of the abacavir hypersensitive patients, six (46%) were HLA B*5701 positive, compared to five (10%) of the non-hypersensitive patients (odds ratio 7.9 [95% confidence intervals 1.5-41.4], P = 0.006). Pooling of our data on HLA B*5701 with published data resulted in a pooled odds ratio of 29 (95% CI 6.4-132.3; P < 0.0001). The cost-effectiveness model demonstrated that depending on the choice of comparator, routine testing for HLA B*5701 ranged from being a dominant strategy (less expensive and more beneficial than not testing) to an incremental cost-effectiveness ratio (versus no testing) of Euro 22,811 per hypersensitivity reaction avoided. CONCLUSIONS: Abacavir hypersensitivity is associated with HLA B*5701, and pre-prescription pharmacogenetic testing for this appears to be a cost-effective use of healthcare resources.

Mechanisms of drug hypersensitivity in HIV-infected patients: the role of the immune system.

Drug hypersensitivity is a major problem in HIV medicine. These reactions limit the choice of antiretrovirals that can be used in a patient and, at times, can lead to failure to administer an adequate regimen. Hypersensitivity reactions occur in a minority of patients, but represent a high cost both to the patient and to health services. Our current understanding of these reactions is based on the hapten and the danger hypotheses, which state that a drug signal by itself is insufficient to induce an immune response but must be accompanied by co-stimulatory or danger signals. Furthermore, individual susceptibility to a hypersensitivity reaction may be determined by genetic factors. In this review, we explore our understanding of the immunological mechanisms of hypersensitivity to drugs used in HIV-positive patients, by using sulphamethoxazole and abacavir as paradigms. A deeper understanding of the mechanism(s) of these reactions will help us in their prevention, diagnosis and treatment.

Characterization of sulfamethoxazole and sulfamethoxazole metabolite-specific T-cell responses in animals and humans.

Sulfamethoxazole (SMX) is associated with hypersensitivity reactions. Identification of drug-specific lymphocytes from hypersensitive patients suggests involvement of the immune system. Lymphocytes from humans recognize SMX and nitroso-SMX (SMX-NO), whereas cells from sensitized rats recognize only SMX-NO. In this investigation, we study the nature of SMX-specific T cells in four species. Male rats, mice, and rabbits were immunized with SMX (50 mg kg-1) or SMX-NO (1 mg kg-1). Lymphocytes and/or splenocytes were isolated and incubated with SMX, SMX-hydroxylamine or SMX-NO and proliferation were measured. Lymphocytes were also isolated from SMX-hypersensitive patients (n = 3) and drug-specific proliferation was measured. In addition, rabbits were bled fortnightly for 4 months to determine whether SMX-NO-specific T cells cross-react with SMX. To confirm that SMX-NO responses were due to covalent binding and not cross-reactivity, cells were pulsed with SMX-NO and/or coincubated with glutathione. Splenocytes from mice, rats, and rabbits proliferated when stimulated with SMX-NO, but not SMX. A 2-h pulse with SMX-NO was sufficient for proliferation, whereas cells coincubated with SMX-NO and glutathione did not proliferate. Rabbit lymphocytes proliferated in the presence of SMX-NO and SMX-hydroxylamine, but not SMX. SMX-hydroxylamine was converted to SMX-NO in culture. The SMXNO-specific response of rabbit lymphocytes was maintained for at least 4 months and the cells did not cross-react with SMX. Human lymphocytes from hypersensitive patients proliferated in the presence of SMX and both metabolites. These results highlight important differences in T-cell recognition of drug (metabolite) antigens in animals that have been sensitized against a drug metabolite and patients with hypersensitivity to the drug.

Slow acetylator phenotype and genotype in HIV-positive patients with sulphamethoxazole hypersensitivity.

AIMS: To test the role of acetylator status, and to investigate the reported discrepancy between acetylator phenotype and genotype in HIV-positive patients with sulphamethoxazole (SMX) hypersensitivity. METHODS: Forty HIV-positive patients (32 of whom were SMX-hypersensitive), and 26 healthy volunteers, were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, and phenotyped using dapsone (50 mg) as a probe, for acetylator status. Sequencing of the NAT2 exon was performed where discrepancy between phenotyping and genotyping was detected. Our results were also pooled with published studies addressing slow acetylator status in HIV-positive SMX-hypersensitive patients. RESULTS: Slow acetylator genotype and phenotype frequencies did not differ between HIV-positive SMX-hypersensitive and nonhypersensitive patients, and healthy controls, which was further confirmed in a meta-analysis of published studies (pooled odds ratio 2.25, 95% confidence interval 0.45, 11.17). Discordance between phenotype and genotype was resolved in four of the subjects by sequencing of the whole NAT2 exon, which revealed rare mutations, leaving three (9%) HIV-positive SMX-hypersensitive patients and one (4%) healthy volunteer who continued to demonstrate the discordance. CONCLUSIONS: Slow acetylator phenotype or genotype is unlikely to predispose to SMX hypersensitivity in HIV-positive patients, although a minor role cannot be excluded. Phenotype-genotype discrepancies are partly due to nondetection of all rare alleles by PCR methodology, and can be circumvented by sequencing of the gene in patients showing a discrepancy.

TNF-alpha promoter region gene polymorphisms in HIV-positive patients with lipodystrophy.

OBJECTIVE: The pathogenic mechanisms underlying lipodystrophy in HIV-positive patients are largely unknown. TNF-alpha has many actions that are consistent with the features of lipodystrophy; therefore, an analysis was carried out to determine whether functionally active polymorphisms in the promoter region of the TNF-alpha gene are associated with the development of lipodystrophy. DESIGN: Genetic case-control association study. METHODS: Individuals were genotyped for the -238 and -308 polymorphisms in the TNF-alpha gene using polymerase chain reaction-restriction fragment length polymorphism analysis. The genotype and allele frequencies for 61 HIV-positive patients with lipodystrophy were compared with (a) 35 HIV-positive patients with no evidence of lipodystrophy and (b) 239 healthy HIV-negative individuals. RESULTS: The frequency of the variant rare -238 allele was significantly different (P = 0.01) in HIV-positive patients with lipodystrophy than in those without lipodystrophy. At the genotype level, a trend towards a difference between patients with and without lipodystrophy was observed (chi2 for linear trend 5.2, P = 0.02). For the -308 polymorphism, no difference was found in genotype and allele frequencies between HIV patients with and without lipodystrophy. CONCLUSIONS: The data suggest that the -238 (but not the -308) promoter region TNF-alpha gene polymorphism is a determinant in the development of HIV-related lipodystrophy. However, the results need to be confirmed in larger numbers of patients as well as in an ethnically diverse population.