Biomedical subjects
Publications and source records attributed to B Gazzard.
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Individuals coinfected with human immunodeficiency virus 1 (HIV-1) and hepatitis B virus (HBV) often receive treatment with an antiretroviral regimen including lamivudine. Lamivudine monotherapy for HBV may lead to drug-resistant mutations in a significant number of patients. The virological and biochemical responses of 8 patients coinfected with HBV/HIV-1 treated with both lamivudine and famciclovir were studied. Patients exhibiting HBV viral rebound at 1 year were analyzed for the emergence of HBV polymerase mutations. Only 1 patient had no prior exposure to lamivudine. Addition of famciclovir to the treatment regimen resulted in a median fall in HBV DNA level of 0.33 log(10) at 3 months and an overall rise in HBV DNA level of 3 log(10) at 12 months. The only patient in whom durable viral suppression and HBV e antigen seroconversion were noted began receiving lamivudine and famciclovir simultaneously. HBV polymerase gene sequencing identified resistance-associated mutations in 6 of 7 patients with viral rebound. Sequential nucleoside analogue therapy is unlikely to be successful in achieving long-term suppression of HBV replication, and combination therapy should be considered at treatment initiation.
Most patients with chronic HIV-1 infection lack functional CD4(+) and CD8(+) HIV-1-specific T cells with proliferative and cytolytic capacity, respectively. This is despite being able to produce intracellular cytokines in response to viral antigens. Protease inhibitor (PI)-based highly active anti-retroviral therapy (HAART) is unable to completely eradicate virus and fails to enable total restoration of immunity including induction of anti-HIV-1 responses. We have taken novel approaches towards the treatment of chronic HIV-1 disease with the aim of instigating long-term non-progressor status and depletion of virus reservoirs. HIV-1-specific CD4(+) and CD8(+) T cell responses were measured following the administration of cytokines, during therapeutic vaccination, and following treatment interruption (TI) or drug therapy change. Administration of cytokines, with or without therapeutic vaccination, in HAART treated patients, improved both CD4(+) and CD8(+) HIV-1-specific T cell responses even in late-stage disease. Virus-specific T cell responses were also seen during TI or when transient viraemia was apparent, and following therapy change from a PI- to a non-nucleoside-based HAART regimen. Reconstitution of HIV-1-specific immune responses was found to be transient and reversal to the previous anergic state was rapid. Viral reservoirs in the latently infected resting CD4(+) T cells, on follicular dendritic cells of germinal centers or even in infected thymic epithelium may be involved in clonal suppression and anergy. These may present major obstacles to the maintenance of HIV-1-specific responses and the eventual eradication of HIV-1.
Human blood contains at least 2 subpopulations of antigen-presenting dendritic cells (DCs) that can be differentiated by their expression of CD11c. Myeloid DCs (myDCs), which are CD11c(+), trap invading pathogens in the tissues and then migrate to lymphoid tissues where they stimulate pathogen-specific T-cell responses. Plasmacytoid DCs (pcDCs), which are CD11c(-), secrete interferon-alpha in response to viral infections. This study reports that in HIV-1 infection there is a progressive depletion of both these DC populations and that this correlates with an increasing HIV-1 plasma virus load. The median numbers of myDCs and pcDCs were 6978/mL and 9299/mL, respectively, in healthy male controls and 2298/mL and 1640/mL, respectively, in patients with more than 10(5) HIV-1 RNA copies/mL. Both DC populations expressed CD4, CCR5, and CXCR4. The findings suggest that loss of DCs in HIV infection may contribute to disease progression.
OBJECTIVE: To assess the antiviral efficacy, safety and adherence in patients switched to an abacavir-containing nucleoside reverse transcriptase inhibitor (NRTI) regimen after long-term HIV-1 RNA suppression with a dual NRTI/protease inhibitor (PI) combination. METHODS: In an open-label, multicentre study, patients receiving 2NRTI plus PI for at least 6 months, with a history of undetectable plasma HIV-1 RNA since the initiation of therapy and plasma HIV-1 RNA < 50 copies/ml at screening, were randomly assigned to replace the PI with abacavir (n = 105) or continue the same treatment (n = 106). Clinical assessments included plasma HIV-1 RNA, chemistry, haematology, lymphocyte counts, and adverse event reports. Adherence to treatment was assessed by patient self-report. RESULTS: A significantly longer time to treatment failure was demonstrated in the abacavir arm compared with the PI arm (P = 0.03) while treatment failure was experienced by significantly more patients in the PI arm: 24 (23%) versus 12 (12%) (P = 0.03). Therapy-limiting toxicity led to treatment failure in eight versus 14 cases in the abacavir and PI arms, respectively, whereas virological rebound was the cause in four versus two cases. Significant reductions in cholesterol and non-fasting triglyceride plasma levels at 48 weeks were observed in the abacavir arm (P < 0.001 andP = 0.035, respectively). The number of patients reporting no difficulty in taking their therapy showed a marked increase from baseline in the abacavir arm. CONCLUSION: The replacement of PI by abacavir in a triple combination regimen following prolonged suppression of plasma HIV-1 RNA provides continued virological suppression, significant improvements in lipid abnormalities and enhanced ease of dosing.
The steady-state pharmacokinetics of efavirenz and nevirapine, when used in combination to treat human immunodeficiency virus type 1 (HIV-1)-infected subjects, were investigated. HIV-1-infected persons who had used efavirenz (600 mg once daily) for > or =2 weeks were eligible for study inclusion. The plasma pharmacokinetics of efavirenz were determined over 24 h. Subsequently, nevirapine (400 mg once daily) was added to the regimen. After 4 weeks, the pharmacokinetics of efavirenz and nevirapine were assessed over 24 h. The differences between the pharmacokinetic parameters of efavirenz with and without nevirapine were analyzed, and the pharmacokinetics of nevirapine were compared with those in historical control patients. The exposure to efavirenz when combined with nevirapine was significantly decreased by 22% (area under the plasma concentration vs. time curve), 36% (minimum plasma concentration), and 17% (maximum plasma concentration). Nevirapine pharmacokinetics appear to be unaffected by coadministration of efavirenz, compared with data from historical control patients.
OBJECTIVES: To evaluate whether successful, long-term immune reconstitution in vivo can be achieved in end-stage AIDS patients following antiretroviral therapy (ART). METHODS: A 1-year prospective study of changes of CD4+ and CD8+ T-cell surface phenotypes, T-cell receptor (TCR) repertoires and capacity to control in vivo replication of cytomegalovirus (CMV) was performed in five treatment-naive end-stage AIDS patients (median CD4+ T-cell counts of 19 cells/microL) following therapy. Proportions of CD45RA+, CD45RO+ and CD28+ cells within the CD4+ and CD8+ subsets, were determined by flow cytometry. Changes in TCR Vbeta repertoires within the CD4+ and CD8+ T-cell compartments were evaluated using CDR3 spectratyping. CMV replication was determined by a sensitive polymerase chain reaction (PCR) assay using whole blood. RESULTS: Following ART, proportionate increases in 'naive' (CD45RA+) and 'memory' (CD45RO+) T cells were observed within both CD4+ and CD8+ T-cell subsets, while increased numbers of CD28+ T cells were mainly observed within the CD4+ subset. Diversification of CD4+ and CD8+ TCR repertoires was established concomitantly with renewed in vivo control of CMV replication. CONCLUSIONS: An important degree of molecular and functional immune recovery is possible in end-stage AIDS patients introduced to therapy. Diversification of TCR repertoires and the in vivo restoration of immunocompetence to control opportunistic infections clearly show that an important degree of molecular immune reconstitution is established following the initiation of ART even in late-stage AIDS.
OBJECTIVES: To determine whether systemic or deep fungal infections can be prevented, a double-blind, placebo-controlled, phase III trial of itraconazole prophylaxis was undertaken in HIV-infected patients. METHODS: HIV-1 infected patients with CD4 counts < 300 cells/microL were treated with itraconazole (200 mg per day) or matching placebo and followed for 2 years. Development of deep fungal infections, episodes of mucocutaneous candidiasis, change in CD4 count, survival and safety data were collected at each study visit. RESULTS: Three hundred and seventy-four patients received study medication, 187 were given itraconazole and 187 matching placebo. Time to development of deep fungal infection did not differ between groups, in an intention to treat analysis. Low CD4 cell count and prior use of Pneumocystis carinii pneumonia (PCP) prophylaxis were significantly associated with a more rapid development of deep fungal infection (P = 0.044 and 0.017, respectively). Itraconazole treatment significantly reduced the incidence of oral candidosis (25% vs. 48% P < 0.001) and time to development of oral candidosis (508 vs. 413 days, P < 0.001) but not the number of deep fungal infections (11 vs. 13). Survival did not differ significantly between groups (nine vs. 14 deaths). CD4 counts decreased significantly over time in both study arms. Adverse events did not differ between groups; 20% vs. 23% stopped study medication due to an adverse experience. CONCLUSIONS: Although itraconazole prophylaxis significantly reduced the number and time to development of oral candidosis, too few episodes of deep fungal infection were noted to determine whether itraconazole prophylaxis was effective for this condition. Chronic itraconazole treatment is well tolerated in HIV-infected patients with marked immunodeficiency.
In this study, we compared human immunodeficiency virus (HIV) type 1-specific proliferative responses with HIV-1-induced intracellular cytokine production in a cohort of clinically nonprogressing patients and individuals with progressive HIV-1 infection. We found strong HIV-1-specific proliferative responses in the clinical nonprogressor cohort that correlated with significant numbers of circulating HIV-1-specific CD4(+) T cells. In contrast, HIV-1-specific proliferative responses were absent in most individuals with progressive HIV-1 infection, even though interferon-gamma-producing HIV-1-specific CD4(+) T cells were detectable by flow cytometry. The implication of these data is that the important dysfunction seen in most HIV-positive patients from very early in disease may be an inability of HIV-1-specific CD4(+) memory T cells to proliferate in response to HIV antigens rather than an absolute loss of circulating virus-specific CD4(+) T cells.
OBJECTIVE: To examine temporal trends (1986-1996) in the CD4 cell count at first HIV-1 positive test and initial AIDS diagnosis, and the influence of selected patient characteristics and treatment factors on these trends. DESIGN: A retrospective clinic-based study. SETTING: Three hospital-based clinics in West London. PATIENTS: A group of 5921 adult HIV-1-seropositive persons and 2835 reported patients with AIDS over a 10-year period from 1 January 1986 to 1 October 1996. METHODS: The CD4 cell count at HIV diagnosis (CD4HIV) was defined as the nearest CD4 cell count to within 2 months of HIV diagnosis; and the CD4 cell count at AIDS diagnosis (CD4AIDS) as the last CD4 cell count in the two months prior to the development of AIDS. Simple and multiple linear regression analysis were used to examine the influence of selected covariates on CD4HIV and CD4AIDS. RESULTS: The percentage of patients with an available CD4HIV and CD4AIDS increased from less than 5% in 1987 to 53% and 40%, respectively, in 1990, and 79% and 48%, respectively, in 1996. Patients with a missing CD4HIV or CD4AIDS were younger and less likely to have received antiretroviral therapy or prophylaxis for Pneumocystis carinii pneumonia (PCP). There was no significant change in CD4HIV over a 10-year period (median 334 x 10(6) cells/l), but a lower CD4HIV was associated with older age at presentation and injecting drug use. There was a delay in the onset of clinical AIDS, with a fall in the median CD4AIDS value from 99 x 10(6) cells/l prior to 1987, to 58 x 10(6) cells/l in 1990, 68 x 10(6) cells/l in 1994 and 60 x 10(6) cells/l in 1996; this decline in onset was seen for PCP as well as for cytomegalovirus and atypical mycobacterial infections. At all time periods, a lower CD4AIDS was associated with combined use of antiretroviral therapy and PCP prophylaxis. After adjustment for use of antiretroviral therapy and PCP prophylaxis prior to AIDS diagnosis, year of diagnosis was no longer associated with CD4AIDS. There was a significant trend towards an improved survival following AIDS diagnosis from 20.1 months prior to 1988, to 20.3 months (1989-1990), 21.0 months (1991-1992) and 22.1 (1993-1994) (P < 0.0005). CONCLUSIONS: The observed decline in CD4AIDS value was related to the introduction of antiretroviral therapy in 1988, and PCP prophylaxis in 1989. Temporal changes in the CD4 cell count at HIV and AIDS diagnosis among different demographic groups can provide insights into the changing natural history of the HIV epidemic and access to medical care. We recommend monitoring of the CD4 cell count at new HIV and AIDS diagnosis and at initiation of antiretroviral therapy as additional measures in national HIV/AIDS surveillance.
There is an increased frequency of invasive anal cancer in HIV-seropositive men. Early treatment strategies in this patient group employed reduced dosages of chemotherapy or radiotherapy alone to reduce toxicity. Since 1989 we have used combined modality treatment consisting of chemotherapy 5-fluorouracil (5-FU) and mitomycin C, and concomitant radical radiotherapy to the pelvis (38-51 Gy in 20-30 fractions), with most patients receiving a perineal boost (10-18 Gy). 12 homosexual HIV-positive men have been treated. The median CD4 count at diagnosis of anal cancer was 209 cells/microl (range: 29-380 cells/microl), 5 had prior AIDS defining diagnoses. No patients had metastatic disease. Complete remissions were obtained in 9/11 evaluable patients and in 1 further patient following surgery. 2 patients relapsed both within 6 months of diagnosis. At a median follow-up of 4.8 years (range: 0.4-10 years), 4 patients have died (2 from anal cancer, 1 from treatment-related consequences and 1 from opportunistic infection in remission). Actuarial 2-year survival is 60% (95% confidence interval (CI): 29-91%). Grade 3 haematological toxicity was recorded in 3 patients, grade 4 and 5 gastrointestinal toxicity in 1 patient each and grade 3 skin toxicity in 1 patient. Radical chemoradiation may be given safely at conventional doses in HIV-positive patients, with a high complete response rate.
Treatment of HIV-1-infected individuals with a combination of anti-retroviral agents results in sustained suppression of HIV-1 replication, as evidenced by a reduction in plasma viral RNA to levels below the limit of detection of available assays. However, even in patients whose plasma viral RNA levels have been suppressed to below detectable levels for up to 30 months, replication-competent virus can routinely be recovered from patient peripheral blood mononuclear cells and from semen. A reservoir of latently infected cells established early in infection may be involved in the maintenance of viral persistence despite highly active anti-retroviral therapy. However, whether virus replication persists in such patients is unknown. HIV-1 cDNA episomes are labile products of virus infection and indicative of recent infection events. Using episome-specific PCR, we demonstrate here ongoing virus replication in a large percentage of infected individuals on highly active anti-retroviral therapy, despite sustained undetectable levels of plasma viral RNA. The presence of a reservoir of 'covert' virus replication in patients on highly active anti-retroviral therapy has important implications for the clinical management of HIV-1-infected individuals and for the development of virus eradication strategies.
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OBJECTIVE: As the pro-inflammatory cytokine tumour necrosis factor-alpha is greater in microsporidiosis than cryptosporidiosis, there may be a distinct metabolic response between the two organisms. DESIGN: Male HIV seropositive subjects with an untreated AIDS-defining diagnosis of microsporidiosis or cryptosporidiosis had measurement of oxygen consumption and carbon dioxide production by indirect calorimetry and body composition analysis to express resting energy expenditure (REE) and substrate oxidation per kilogram of metabolically active tissue. METHODS: Resting energy expenditure (REE), non-protein respiratory quotient (NPRQ), fat and carbohydrate oxidation were calculated from respiratory gas analysis. Fat, fat-free and appendicular muscle masses were measured by dual-energy X-ray absorptiometry. Subjects with protozoal diarrhoea were compared to other newly diagnosed, active opportunistic infections. Controls were asymptomatic HIV-seropositive men matched by peripheral CD4 count. RESULTS: Seven subjects with microsporidiosis and six with cryptosporidiosis were compared with 24 subjects with other AIDS-defining diagnosis (Pneumocystis carinii pneumonia, cytomegalovirus enteritis and Mycobacterium avium-intracellulare) and 10 controls free from secondary infection. Subjects with cryptosporidiosis had a decreased REE, a significantly increased NPRQ (P< 0.05), decreased fat oxidation (P < 0.05) and increased carbohydrate oxidation compared to microsporidiosis. Subjects with other AIDS diagnoses had an increased REE (P < 0.01) and fat oxidation and decreased carbohydrate oxidation compared to cryptosporidiosis, and a similar metabolic response to microsporidiosis. CONCLUSIONS: The metabolic response to cryptosporidiosis differs from microsporidiosis and associated weight loss may be mediated by different mechanisms. Metabolism in other AIDS diagnoses, including microsporidiosis, is compatible with a cachectic response.
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BACKGROUND: Gastrointestinal symptoms are distressing features of human immunodeficiency virus (HIV) infection, and management is often empirical, including withdrawal of dietary lactose. We assessed the prevalence and severity of intestinal disaccharidase deficiency in vitro and in vivo. METHODS: Fifty-four HIV-seropositive patients (19 HIV well +/- mild diarrhoea, 7 acquired immunodeficiency syndrome (AIDS) well, and 28 AIDS with diarrhoea) were studied with a combined non-invasive absorption-permeability-disaccharidase test that enables quantitative assessment of the rate of intestinal hydrolysis of lactose, sucrose, and palatinose. Thirty patients had jejunal biopsy specimens suitable for histomorphometric assessment, and 36 had in vitro disaccharidase activity measurement. RESULTS: Patients with HIV (with mild diarrhoea) and AIDS (with and without severe diarrhoea) had frequent but mild histomorphometric changes in jejunal specimens. This was associated with frequent (21%-100%) and often severe in vitro jejunal disaccharidase deficiency. In vivo hydrolysis of lactose, sucrose, and palatinose was impaired in 25%-75% of patients, apart from HIV well patients, who were normal. The prevalence of the in vivo lactase and sucrase deficiency was significantly (P < 0.006) lower than in vitro and severe in about 30%. CONCLUSIONS: Intestinal disaccharidase deficiency is common both in vitro and in vivo in HIV-seropositive patients but sufficiently severe to consider lactose withdrawal only in about a quarter of the patients with AIDS and diarrhoea.
Pulmonary thromboembolism is not considered a common cause of morbidity in HIV disease. Although anti-phospholipid antibodies are often seen in HIV disease, they are not associated with an increased thrombotic risk. Computed tomographic (CT) pulmonary angiography has been described as the imaging modality of first choice, as abnormal baseline chest X-rays may reduce the diagnostic utility of ventilation perfusion (VIQ) scanning. In HIV-negative individuals D-dimer testing has been shown to be a good screening tool in suspected pulmonary embolism. We present 2 cases where the diagnosis of pulmonary embolus was established using tests for the clotting degradation products D-dimers.
Although the effect of highly active antiretroviral therapy (HAART) on HIV-1 replication has been established, the mechanisms involved in restoration of immune responses and reconstitution remain unknown. This study provides evidence of changes in expression of type 1 and type 2 cytokine-specific mRNA occurring during HIV-1 infection, before and after initiation of HAART. Unstimulated PBMCs from nine HIV-1-infected individuals obtained at different time intervals before and after the initiation of HAART were assessed for specific IFN-gamma, IL-2, IL-4, and IL-10 mRNA expression, using RT-PCR. Correlation with CD4+ T cell counts and viral load was also carried out. Before initiation of HAART, in all patients, little expression of specific IFN-gamma and IL-2 (type 1 cytokine) mRNA was noted. In contrast, expression of specific IL-4 and/or IL-10 (type 2) mRNA was readily detectable in the majority of patients. After initiation of HAART there was a continuous increase in IFN-gamma and IL-2 mRNA expression, although the latter occurred in lower amounts. This paralleled a dramatic reduction in viral load and increase in CD4+ T cell counts. Type 2 cytokine-specific mRNA expression fell to undetectable levels and in some cases reappeared later in the course of HAART. Predominant expression of type 2 cytokine mRNA, before initiation of HAART, concurs with previous findings of a dominant antiproliferative, type 2 cytokine profile during HIV-1 infection. Reversion of the cytokine profile, after HAART, to a strong type 1 profile suggests that in addition to suppressing virus replication directly the immune system may be given a chance to recover.