Granulocyte-macrophage colony-stimulating factor and fluconazole enhance anti-cryptococcal activity of monocytes from AIDS patients

Cryptococcal infection in haematologic malignancies and haematopoietic stem cell transplantation

This review summarises both the recent and relevant studies about cryptococcal infections in haematologic malignancies and haematopoietic stem cell transplantation. Although uncommon in this patient population, this infection carries a high mortality, especially if left untreated. Given the limited data, we draw some conclusions with respect to management from the solid organ transplantation and HIV-infected literature. Herein, we discuss cryptococcosis with a particular attention to its background, epidemiology, risk factors, clinical presentation, diagnosis, treatment and prevention in this group.

Unusual Presentation of Severe Endobronchial Obstruction Caused by Cryptococcus gattii in a Child

Disease caused by Cryptococcus gattii typically manifests as meningoencephalitis or pulmonary nodules. Endobronchial lesions are rare, and most cases are caused by Cryptococcus neoformans. We describe here a case of endobronchial disease in a child caused by C gattii. The disease spectrum in this patient was notable for the discovery of anti-granulocyte macrophage colony-stimulating factor autoantibodies.

Modulating host immune responses to fight invasive fungal infections

Modulation of host immunity in invasive fungal infection is an appealing but as yet mostly elusive treatment strategy. Animal studies in invasive candidiasis and aspergillosis have demonstrated beneficial effects of colony stimulating factors, interferon-gamma and monoclonal antibodies. More recent studies transfusing leukocytes pre-loaded with lipophilic anti-fungal drugs, or modulated T-cells, along with novel vaccination strategies show great promise. The translation of immune therapies into clinical studies has been limited to date but this is changing and the results of new Candida vaccine trials are eagerly awaited. Immune modulation in HIV-associated mycoses remains complicated by the risk of immune reconstitution inflammatory syndrome and although exogenous interferon-gamma therapy may be beneficial in cryptococcal meningitis, early initiation of anti-retroviral therapy leads to increased mortality. Further study is required to better target protective immune responses.

Autoantibodies to Granulocyte-Macrophage Colony-Stimulating Factor Associated With Severe and Unusual Manifestations of Cryptococcus gattii Infections

Cryptococcus gattii infections, especially including those with severe clinical manifestations, may be related to underlying host immunologic factors. We present 2 cases with autoantibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF), a key cytokine in macrophage function. Immunologic evaluation for anti-GM-CSF antibodies may be important to inform management and counseling.

Is Cryptococcus gattii a Primary Pathogen?

The two etiologic agents of cryptococcal meningoencephalitis, Cryptococcus neoformans and C. gattii, have been commonly designated as either an opportunistic pathogen for the first species or as a primary pathogen for the second species. Such a distinction has been based on epidemiological findings that the majority of patients presenting meningoencephalitis caused by C. neoformans are immunocompromised while C. gattii infection has been reported more often in immunocompetent patients. A recent report, however, showed that GM-CSF (granulocyte-macrophage colony-stimulating factor) neutralizing antibodies were prevalent in the plasma of "apparently immunocompetent" C. gattii patients with meningoencephalitis. Because GM-CSF is essential for differentiation of monocytes to macrophages and modulating the immune response, it is not surprising that the lack of GM-CSF function predisposes otherwise healthy individuals to infection via inhalation of environmental pathogens such as C. gattii. Since the test for anti-GM-CSF autoantibodies is not included in routine immunological profiling at most hospitals, healthy patients with GM-CSF neutralizing antibodies are usually categorized as immunocompetent. It is likely that a comprehensive immunological evaluation of patients with C. gattii meningoencephalitis, who had been diagnosed as immunocompetent, would reveal a majority of them had hidden immune dysfunction. This paper reviews the relationship between GM-CSF neutralizing antibodies and the risk for C. gattii infection with CNS involvement.

Compartmentalization of innate immune responses in the central nervous system during cryptococcal meningitis/HIV coinfection

OBJECTIVE

The role of innate immunity in the pathogenesis of cryptococcal meningitis is unclear. We hypothesized that natural killer (NK) cell and monocyte responses show central nervous system (CNS) compartment-specific profiles, and are altered by antifungal therapy and combination antiretroviral therapy (cART) during cryptococcal meningitis/HIV coinfection.

DESIGN

Substudy of a prospective cohort study of adults with cryptococcal meningitis/HIV coinfection in Durban, South Africa.

METHODS

We used multiparametric flow cytometry to study compartmentalization of subsets, CD69 (a marker of activation), CXCR3 and CX3CR1 expression, and cytokine secretion of NK cells and monocytes in freshly collected blood and cerebrospinal fluid (CSF) at diagnosis (n = 23), completion of antifungal therapy induction (n = 19), and after a further 4 weeks of cART (n = 9).

RESULTS

Relative to blood, CSF was enriched with CD56(bright) (immunoregulatory) NK cells (P = 0.0004). At enrolment, CXCR3 expression was more frequent among blood CD56(bright) than either blood CD56(dim) (P < 0.0001) or CSF CD56(bright) (P = 0.0002) NK cells. Antifungal therapy diminished blood (P < 0.05), but not CSF CXCR3(pos) NK-cell proportions nor CX3CR1(pos) NK-cell proportions. CD56(bright) and CD56(dim) NK cells were more activated in CSF than blood (P < 0.0001). Antifungal therapy induction reduced CD56(dim) NK-cell activation in CSF (P = 0.02). Activation of blood CD56(bright) and CD56(dim) NK cells was diminished following cART commencement (P < 0.0001, P = 0.03). Immunoregulatory NK cells in CSF tended to secrete higher levels of CXCL10 (P = 0.06) and lower levels of tumor necrosis factor α (P = 0.06) than blood immunoregulatory NK cells. CSF was enriched with nonclassical monocytes (P = 0.001), but antifungal therapy restored proportions of classical monocytes (P = 0.007).

CONCLUSION

These results highlight CNS activation, trafficking, and function of NK cells and monocytes in cryptococcal meningitis/HIV and implicate immunoregulatory NK cells and proinflammatory monocytes as potential modulators of cryptococcal meningitis pathogenesis during HIV coinfection.

Anti-GM-CSF autoantibodies in patients with cryptococcal meningitis

Cryptococcal meningitis has been described in immunocompromised patients, as well as in those for whom no immune defect has been identified. GM-CSF regulates the function of phagocytes and pulmonary alveolar macrophages, critical elements in cryptococcal control. We performed clinical histories, immunological evaluation, and anticytokine autoantibody screening in four current patients with cryptococcal meningitis and identified and tested 103 archived plasma/cerebrospinal fluid samples from patients with cryptococcal meningitis. We assessed the ability of anti-GM-CSF autoantibody-containing plasmas to inhibit GM-CSF signaling. We recognized anti-GM-CSF autoantibodies in an otherwise healthy female with cryptococcal meningitis who later developed pulmonary alveolar proteinosis (PAP). Her diagnosis prompted screening of patients with cryptococcal meningitis for anticytokine autoantibodies. We identified seven HIV-negative patients with cryptococcal meningitis who tested positive for high-titer anti-GM-CSF autoantibodies. Two of the seven later developed evidence of PAP. Plasma from all patients prevented GM-CSF-induced STAT5 phosphorylation and MIP-1α production in normal PBMCs. This effect was limited to their IgG fraction. Anti-GM-CSF autoantibodies are associated with some cases of cryptococcal meningitis in otherwise immunocompetent patients. These cases need not have associated PAP.

Clinical features and serum biomarkers in HIV immune reconstitution inflammatory syndrome after cryptococcal meningitis: a prospective cohort study

BACKGROUND

Although antiretroviral therapy (ART) improves survival in persons with cryptococcal meningitis (CM) and AIDS, ART frequently elicits HIV immune reconstitution inflammatory syndrome (IRIS), an exaggerated and frequently deadly inflammatory reaction that complicates recovery from immunodeficiency. The pathogenesis of IRIS is poorly understood and prediction of IRIS is not possible.

METHODS AND FINDINGS

We prospectively followed 101 ART-naïve Ugandans with AIDS and recent CM for one year after initiating ART, and used Luminex multiplex assays to compare serum cytokine levels in participants who did or did not develop IRIS. IRIS occurred in 45% of participants with recent CM on ART, including 30% with central nervous system (CNS) manifestations. The median time to CM-IRIS was 8.8 wk on ART. Overall mortality on ART was 36% with IRIS and 21% without IRIS. CM-IRIS was independently associated with death (HR = 2.3, 95% CI 1.1-5.1, p = 0.04). Patients experiencing subsequent CM-IRIS had 4-fold higher median serum cryptococcal antigen (CRAG) levels pre-ART (p = 0.006). Higher pre-ART levels of interleukin (IL)-4 and IL-17 as well as lower tumor necrosis factor (TNF)-α, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and vascular endothelial growth factor (VEGF) predicted future IRIS in multivariate analyses (area under the curve [AUC] = 0.82). An algorithm based on seven pre-ART serum biomarkers was a robust tool for stratifying high (83%), moderate (48%), and low risk (23%) for IRIS in the cohort. After ART was initiated, increasing levels of C-reactive protein (CRP), D-dimer, IL-6, IL-7, IL-13, G-CSF, or IL-1RA were associated with increasing hazard of IRIS by time-to-event analysis (each p≤0.001). At the time of IRIS onset, multiple proinflammatory cytokine responses were present, including CRP and IL-6. Mortality was predicted by pre-ART increasing IL-17, decreasing GM-CSF, and CRP level >32 mg/l (highest quartile). Pre-ART CRP level >32 mg/l alone was associated with future death (OR = 8.3, 95% CI 2.7-25.6, p<0.001).

CONCLUSIONS

Pre-ART increases in Th(17) and Th(2) responses (e.g., IL-17, IL-4) and lack of proinflammatory cytokine responses (e.g., TNF-α, G-CSF, GM-CSF, VEGF) predispose individuals to subsequent IRIS, perhaps as biomarkers of immune dysfunction and poor initial clearance of CRAG. Although requiring validation, these biomarkers might be an objective tool to stratify the risk of CM-IRIS and death, and could be used clinically to guide when to start ART or use prophylactic interventions.

A model and risk score for predicting nevirapine-associated rash among HIV-infected patients: in settings of low CD4 cell counts and resource limitation

BACKGROUND

Rash is the most common adverse effect associated with nevirapine (NVP). We aimed to develop a model and risk score for predicting NVP-associated rash among HIV-infected patients with low CD4 cell counts.

METHODS

Cross-sectional study was conducted and 383 HIV-infected patients consecutively enrolled in the study.

RESULTS

Of 222 patients in the training set, 116 (52.2%) were males and median (IQR) age was 35.2 (31.1-42.0) years. Median (IQR) CD4 cell count was 104 (35-225) cells/mm(3). Of these, 72 and 150 patients were in "rash" and "no rash" group, respectively. Four factors were independently associated with rash: a history of drug allergy (odds ratio (OR) 4.01, 95% confidence interval (CI), 1.75-9.20, P = 0.001), body weight <55 kg. (OR 2.02, 95% CI, 1.09-3.76, p = 0.026), not receiving slow dose escalation (OR 2.00, 95% CI, 1.06-3.77, p = 0.032), and no concomitant drug(s) (OR 2.48, 95% CI, 1.32-4.64, p = 0.005). Receiver-operator characteristic analysis yielded area under the curve of 71% and the goodness-of-fit statistics was 6.48 (p = 0.840). The variables were given scores of 14, 7, 7 and 9, respectively. A cutoff >21 points defined the high risk individuals which yielded specificity and positive predictive value of 99% and 69%, respectively, with OR of 3.96 (95% CI, 1.79-8.86, p = 0.001).

CONCLUSIONS

A model and risk score for predicting NVP-associated rash performed well in this study population. It might be useful for predicting the risk of rash before NVP initiation among HIV-infected patients with low CD4 cell counts.

Tissue-specific sequence alterations in the human immunodeficiency virus type 1 envelope favoring CCR5 usage contribute to persistence of dual-tropic virus in the brain

Most human immunodeficiency virus type 1 (HIV-1) strains isolated from the brain use CCR5 for entry into macrophages and microglia. Strains that use both CCR5 and CXCR4 for entry (R5X4 strains) have been identified in the brains of some individuals, but mechanisms underlying the persistence of R5X4 viruses compartmentalized between the brain and other tissue reservoirs are unknown. Here, we characterized changes in the HIV-1 envelope (Env) that enhance the tropism of R5X4 variants for brain or lymphoid tissue. R5X4 Envs derived from the brains of two individuals had enhanced CCR5 usage in fusion assays compared to R5X4 Envs derived from matched spleen or blood, which was associated with reduced dependence on specific residues in the CCR5 N terminus and extracellular loop 1 (ECL1) and ECL3 regions. In contrast, spleen/blood-derived Envs had enhanced CXCR4 usage compared to brain-derived Envs, which was associated with reduced dependence on residues in the CXCR4 N terminus and ECL2 region. Consequently, brain-derived Envs had preferential CCR5 usage for HIV-1 entry into the JC53 cell line, could use either CCR5 or CXCR4 for entry into monocyte-derived macrophages (MDM), and could use CCR5 (albeit inefficiently) for entry into peripheral blood mononuclear cells (PBMC), whereas the entry of spleen-derived Envs was CXCR4 dependent in all three cell types. Mutagenesis studies of Env amino acid variants influencing coreceptor usage showed that S306 in the gp120 V3 region of brain-derived Envs reduces dependence on the CCR5 N terminus and enhances CCR5 usage for HIV-1 entry into PBMC and MDM, whereas R306 in spleen-derived Envs reduces dependence on the CXCR4 N terminus and confers the CXCR4 restricted phenotype. These results identify mechanisms underlying R5X4 HIV-1 persistence in different tissue reservoirs. Tissue-specific changes in the gp120 V3 region that increase the efficiency of CCR5 or CXCR4 usage, and thereby influence coreceptor preference, may enhance the tropism of R5X4 strains for CCR5-expressing macrophage lineage cells in the brain and CXCR4-expressing T cells in lymphoid tissues, respectively.

Characterization of the follicular dendritic cell reservoir of human immunodeficiency virus type 1

Throughout the natural course of human immunodeficiency virus (HIV) infection, follicular dendritic cells (FDCs) trap and retain large quantities of particle-associated HIV RNA in the follicles of secondary lymphoid tissue. We have previously found that murine FDCs in vivo could maintain trapped virus particles in an infectious state for at least 9 months. Here we sought to determine whether human FDCs serve as an HIV reservoir, based on the criteria that virus therein must be replication competent, genetically diverse, and archival in nature. We tested our hypothesis using postmortem cells and tissues obtained from three HIV-infected subjects and antemortem blood samples obtained from one of these subjects. Replication competence was determined using coculture, while genetic diversity and the archival nature of virus were established using phylogenetic and population genetics methods. We found that FDC-trapped virus was replication competent and demonstrated greater genetic diversity than that of virus found in most other tissues and cells. Antiretrovirus-resistant variants that were not present elsewhere were also detected on FDCs. Furthermore, genetic similarity was observed between FDC-trapped HIV and viral species recovered from peripheral blood mononuclear cells obtained 21 and 22 months antemortem, but was not present in samples obtained 4 and 18 months prior to the patient's death, indicating that FDCs can archive HIV. These data indicate that FDCs represent a significant reservoir of infectious and diverse HIV, thereby providing a mechanism for viral persistence for months to years.

Abacavir sulfate/lamivudine/zidovudine fixed combination in the treatment of HIV infection

Treatment of HIV infection has typically been carried out using two nucleoside analogs and a protease inhibitor. Such regimens can be complex and have high pill burdens. Use of alternative regimens, such as triple nucleoside-based regimens, can improve adherence and decrease toxicities associated with protease inhibitor therapy. A formulation of abacavir sulfate/lamivudine/zidovudine allows a dosing schedule of one pill twice daily. The components have performed favorably compared with protease inhibitor-based regimens, such as indinavir. Compared with efavirenz-based regimens, abacavir sulfate/lamivudine/zidovudine has not performed as well. The combination is being studied as a cornerstone for induction maintenance strategies, in which switching a patient to abacavir sulfate/lamivudine/zidovudine has been associated with similar virologic outcomes as continuing with either protease inhibitor- or efavirenz-based regimens. Administration of abacavir sulfate/lamivudine/zidovudine also avoids side effects of antiretroviral therapy, such as hyperlipidemia, but its use is associated with a hypersensitivity reaction in a small number of patients. The combination of abacavir sulfate/lamivudine/zidovudine is an important part of the HIV armamentarium. Its potency and ease of administration make it worth consideration in the treatment of HIV, either by itself or in combination with other agents.

Combination exposure to zidovudine plus sulfamethoxazole-trimethoprim diminishes B-lymphocyte immune responses to Pneumocystis murina infection in healthy mice

We have previously shown that zidovudine plus sulfamethoxazole-trimethoprim exposure decreases immune cell populations in the bone marrow of healthy mice by inducing apoptosis. The hypothesis of the current work was that this toxicity would have an adverse impact on the immune response. To determine this, BALB/c mice were treated with zidovudine, sulfamethoxazole-trimethoprim, the combination of both drugs, or vehicle only (control) via oral gavage for 21 days. On day 4 after dosing completion, the mice were infected intratracheally with 1x10(7) Pneumocystis murina organisms. Immune cell populations (in lung digest, bronchoalveolar lavage fluid, tracheobronchial lymph node, and bone marrow samples), the lung Pneumocystis burden, and serum Pneumocystis-specific antibody titers were determined at days 6, 10, and 20 postinfection. While total bone marrow cellularity was recovered by day 6 postinfection in the combination exposure group, B-cell numbers did not recover until 10 days postinfection, primarily due to the persistent depletion of the late pre-B-cell phenotype. The numbers of CD4+ and CD8+ T cells, as well as the numbers of total B cells and activated B cells in tracheobronchial lymph nodes, were decreased at days 10 and 20 as a result of zidovudine plus sulfamethoxazole-trimethoprim exposure compared to the numbers in the control group. No significant differences in lung lavage or lung digest cell populations were observed. There was a trend of a delay in Pneumocystis clearance in the combination treatment group, and Pneumocystis-specific serum immunoglobulin G titers were reduced at day 20 postinfection. Together, these data indicate that the combination of zidovudine and sulfamethoxazole-trimethoprim adversely affects the humoral immune response to Pneumocystis.

Relationship between Changes in Thymic Emigrants and Cell-Associated HIV-1 Dna in HIV-1-Infected Children Initiating Antiretroviral Therapy

Objectives and methods

To investigate the relationship between cell-associated HIV-1 dynamics and recent thymic T-cell emigrants, HIV-1 DNA and T-cell receptor rearrangement excision circles (TREC, a marker of recent thymic emigrants) were measured in peripheral blood mononuclear cells in 181 samples from 33 HIV-1-infected children followed for 96 weeks after antiretroviral therapy (ART) initiation.

Results

At baseline, HIV-1 DNA was higher in children with higher TREC ( P=0.02) and was not related to age, CD4 or HIV-1 RNA in multivariate analyses ( P>0.3). Overall, TREC increased and HIV-1 DNA decreased significantly after ART initiation, with faster HIV-1 DNA declines in children with higher baseline TREC ( P=0.009). The greatest decreases in HIV-1 DNA occurred in children with the smallest increases in TREC levels during ART ( P=0.002). However, this inverse relationship between changes in HIV-1 DNA and TREC tended to vary according to the phase of HIV-1 RNA decline ( P=0.13); for the same increase in TREC, HIV-1 DNA decline was much smaller during persistent or transient viraemia compared with stable HIV-1 RNA suppression.

Conclusions

Overall, these findings indicate that TREC levels predict HIV-1 DNA response to ART and suggest that immune repopulation by thymic emigrants adversely affects HIV-1 DNA decline in the absence of persistent viral suppression, possibly by providing a cellular source for viral infection and replication.

Zidovudine, lamivudine, and abacavir have different effects on resting cells infected with human immunodeficiency virus in vitro

We have previously described an in vitro model for the evaluation of the effects of different immunomodulatory agents and immunotoxins (ITs) on cells latently infected with human immunodeficiency virus (HIV). We demonstrated that latently infected, replication-competent cells can be generated in vitro after eliminating CD25+ cells with an IT. Thus, by selectively killing the productively infected cells with an anti-CD25 IT we can generate a population of latently infected cells. CD25- cells generated in this manner were treated with nucleoside analog reverse transcriptase inhibitors and subsequently activated with phytohemagglutinin in the presence of the drugs. The antiviral activities of zidovudine (ZDV), lamivudine (3TC), and abacavir (ABC) were evaluated by using this model. 3TC and ABC demonstrated significant activity in decreasing HIV production from recently infected resting cells following their activation, whereas the effect of ZDV was more modest. These results suggest that the differences in antiviral activity of nucleoside analogs on resting cells should be considered when designing drug combinations for the treatment of HIV infection. The model presented here offers a convenient alternative for evaluating the mechanism of action of new antiretroviral agents (J. Saavedra, C. Johnson, J. Koester, M. St. Claire, E. Vitteta, O. Ramilo, 37th Intersci. Conf. Antimicrob. Agents Chemother., abstr. I-59, 1997).

Management of Dyslipidaemia in HIV-Infected Patients Receiving Antiretroviral Therapy

Dyslipidaemia associated with the treatment of HIV infection, particularly with the use of protease inhibitors (PIs), can raise cholesterol and triglyceride (TG) levels to the thresholds indicated for intervention. Recent evidence from epidemiological studies has shown that there are correlations between antiretroviral drug use and increased risks for, and incidences of, cardiovascular disease, including myocardial infarction and coronary heart disease. The primary goals of dyslipidaemia therapy for HIV patients are reductions of both low-density lipoprotein cholesterol (LDL-C) and markedly elevated TG levels. Dietary strategies and exercise programs may be tried, although these have shown inconsistent results. The two options for drug therapy are switching anti-retroviral agents and using lipid-lowering drugs. Each approach is associated with advantages and limitations, and the need to maintain viral suppression must be balanced with the need to treat abnormal lipid levels. Most drug switches replace the PI component with drugs from another antiretroviral class. Selection of drug therapy for lipid lowering depends on the type of dyslipidaemia predominating and the potential for drug interactions. The use of the statins pravastatin and atorvastatin is recommended for the treatment of patients with elevated LDL-C levels and gemfibrozil or fenofibrate for patients with elevated TG concentrations. Development of new PIs with more favourable effects on the lipid profile should be of benefit.

Natural selection and the organ-specific differentiation of HIV-1 V3 hypervariable region

The existence of organ-specific HIV-1 populations within infected hosts has been studied for many years; nonetheless results reported by different authors are somewhat discrepant. To tackle this problem, we used a population genetics approach to analyze previously published data from the V3 hypervariable region of the envelope env gene. Our results are compatible with a population subdivision by organs in 95% of individuals analyzed at autopsy. In addition, populations infecting the nervous system and testicles clearly appear as differentiated subsets of the so-called macrophage-tropic variants. Liver and kidney may harbor differentiated populations as well. Although it is widely accepted that organ compartmentalization arises as a consequence of different selective pressures imposed by different organs, a definitive demonstration has not yet been provided. Our analysis of the pattern of synonymous and nonsynonymous nucleotide substitutions provides evidence supporting this hypothesis, without discarding the role of other evolutionary processes. In contrast, positive selection does not seem to be the mechanism responsible for the evolution of patient-specific sequences.

The role of surrogate markers in the clinical development of antiretroviral therapy: a model for early evaluation of targeted cancer drugs

Both CD4 cell counts and measurements of plasma HIV-1 RNA (i.e. viral load) have become established surrogate markers for predicting treatment and disease outcome in HIV infection, and are instrumental for the evaluation of new antiretroviral drugs in clinical trials. Recently, HIV drug-resistance testing has also become available and has been shown to have prognostic value in providing guidance with antiretroviral therapy. The identification of robust surrogate markers is also an essential requirement for the clinical development of targeted anticancer agents, which unlike their cytotoxic counterparts, are often devoid of the toxicities that have been traditionally used to monitor the efficacy of chemotherapy. In particular, biological or molecular markers that are predictive of a drug effect need to be integrated into early efficacy trials of targeted therapies in order to confirm that the drug is in fact "hitting" the intended target. The full clinical significance of many of the altered cell types or polymorphisms, which are selected by cytostatic agents, remains to be elucidated. However, molecular genotyping of these targets, akin to drug resistance testing for HIV infection, may constitute an important strategy to assist with the selection and monitoring of targeted chemotherapy in cancer patients. Thus, lessons from HIV/AIDS on the value of surrogate makers may assist with the development and optimization of targeted cancer therapy.

An anti-CD45RO immunotoxin kills HIV-latently infected cells from individuals on HAART with little effect on CD8 memory

CD4+ CD45RO+ T cells are the major latent viral reservoir in HIV-infected individuals and hence a major obstacle in curing the disease. An anti-CD45RO immunotoxin (IT) can decrease the number of both productively and latently infected CD4+ T cells obtained from HIV-infected individuals with detectable viremia. In this study, we determined whether this IT could also kill latently infected replication-competent CD4+ T cells obtained from infected individuals without detectable plasma viremia. Our results demonstrate that ex vivo treatment with the anti-CD45RO IT significantly reduced the frequency of these cells. In contrast, the IT had only a modest effect on the cytomegalovirus-specific memory responses of CD8+ T cells. These results suggest that purging latent cells from infected individuals on highly active antiretroviral therapy with the anti-CD45RO IT might reduce the HIV latent reservoir without seriously compromising CD8+ T cell memory responses.

Simplified regimens for treating HIV infection and AIDS

PURPOSE

To review the variables that greatly affect adherence to the complex treatment regimens used in HIV disease and to examine available options that could improve patient outcomes.

DATA SOURCES

Comprehensive review of current medical and scientific literature, drug-prescribing literature, and randomized clinical trials of drug treatments.

CONCLUSIONS

Effective treatment of HIV infection is dependent on consistent adherence to prescribed antiretroviral medications. A large pill burden, multiple daily doses, and adverse events are some of the complexities that negatively impact patient adherence. For example, lipodystrophy and hyperlipidemia are two serious side effects associated with some agents. Once-daily antiretroviral agents offer many advantages over historical treatment options but are associated with possible drawbacks.

IMPLICATIONS FOR PRACTICE

Currently, four single agents are available for once-daily administration, and a few others are under investigation. In addition, combination therapy with either dual or boosted protease inhibitor regimens is becoming a popular way of overcoming the poor pharmacokinetic characteristics of individual protease inhibitors.

Adherence to HAART regimens

The problem of inadequate adherence to prescribed highly active antiretroviral therapy (HAART) drug regimens to treat HIV infection and AIDS is ubiquitous. Adherence can be inadequate despite both provider and patient understanding of the consequences of nonadherence. Successful long-term treatment of HIV/AIDS requires at least 95% adherence to HAART in order to prevent emergence of drug-resistant HIV variants that lead to regimen failure and limit options for future therapy. Despite the prevalence of inadequate adherence, many patients succeed, and HAART has transformed HIV infection into a chronic illness increasingly managed in primary care. The barriers to adherence observed in HIV treatment resemble barriers to the successful treatment of other chronic diseases: regimen complexity, side effects resulting in poor tolerability, patient lifestyle factors, and patient-provider relationships. Treatment of HIV infection has shown that patient-provider collaboration can result in the selection of a lifestyle-tailored regimen characterized by convenient dosing, low pill burden, and tolerable side effects that enhances adherence, effectiveness, and the patient's willingness to remain on anti-HIV therapy long term. This review focuses on the current understanding of adherence reporting, improvement of adherence, and, hence, improvement of treatment outcomes in HIV infection and AIDS.

The 'apparent' hydrolysis of alkyl esters during electrospray ionization

Electrospray ionization (ESI) mass spectrometry was employed to obtain both molecular weight confirmation and structural information for a series of novel alkenyldiarylmethane (ADAM) analogs. The mass spectral data were intended for use during the structure elucidation of ester hydrolysis products formed during an in vitro metabolism study of a series of novel ADAM analogs. The data on the precursor molecules show the presence of the molecular ion peak, [M+H](+), as well as a peak consistent with the hydrolysis product of the original ester ([MH-ROH+H(2)O](+)). However, chemical ionization mass spectrometry, elemental analysis and (1)H NMR data indicated the presence of only the intact diester compounds, suggesting that the formation of the hydrolysis product was an instrumental artifact, i.e., in-beam hydrolysis during ESI or a result of longer ion residence times of the ion trap mass analyzer.

Modulation of human immunodeficiency virus 1 replication by interferon regulatory factors

Transcription of the human immunodeficiency virus (HIV)-1 is controlled by the cooperation of virally encoded and host regulatory proteins. The Tat protein is essential for viral replication, however, expression of Tat after virus entry requires HIV-1 promoter activation. A sequence in the 5' HIV-1 LTR, containing a binding site for transcription factors of the interferon regulatory factors (IRF) family has been suggested to be critical for HIV-1 transcription and replication. Here we show that IRF-1 activates HIV-1 LTR transcription in a dose-dependent fashion and in the absence of Tat. This has biological significance since IRF-1 is produced early upon virus entry, both in cell lines and in primary CD4+ T cells, and before expression of Tat. IRF-1 also cooperates with Tat in amplifying virus gene transcription and replication. This cooperation depends upon a physical interaction that is blocked by overexpression of IRF-8, the natural repressor of IRF-1, and, in turn is released by overexpression of IRF-1. These data suggest a key role of IRF-1 in the early phase of viral replication and/or during viral reactivation from latency, when viral transactivators are absent or present at very low levels, and suggest that the interplay between IRF-1 and IRF-8 may play a key role in virus latency.

Virological suppression at 6 months is related to choice of initial regimen in antiretroviral-naive patients: a cohort study

BACKGROUND

Guidelines recommend both protease inhibitor (PI)- and non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing regimens for initial therapy in HIV-positive individuals whilst clinical trial data comparing treatment options remain limited.

OBJECTIVE

To assess whether drug selection (PI versus NNRTI) in antiretroviral-naive patients is related to virological response at 6 months within a clinical cohort.

DESIGN

Databases from two large clinics were used to identify all treatment-naive patients initiating highly active antiretroviral therapy (PI/ two PI or NNRTI). Statistical models determined the likelihood of suppressing HIV viral load < 500 copies/ml, the risk of treatment failure by 6 months, and factors associated with treatment success.

RESULTS

Of 1109 potentially eligible patients 888 met study criteria and were included; 484 were prescribed a PI (40% indinavir, 41% nelfinavir) and 404 were prescribed NNRTI (40% efavirenz, 60% nevirapine). Three treatment arms were compared: efavirenz versus nevirapine versus PI. After stratification by year and centre and adjustment for baseline variables, only treatment group and baseline viral load remained significantly associated with virological suppression at 6 months. Patients on efavirenz were significantly more likely to achieve an undetectable viral load than those on PI or nevirapine. The relative hazard for nevirapine was 0.77 (95% confidence interval, 0.61-0.96, P = 0.02) and that for PI was 0.74 (95% confidence interval, 0.58-0.94, P = 0.01). Efavirenz also performed better in the analysis of treatment failure at 6 months.

CONCLUSION

Although observational cohort data may be susceptible to significant bias, this study suggests a better initial virological response for efavirenz compared to either nevirapine or the PI. Clinical trial data is required to confirm these findings.

Comparison of the effectiveness of non-nucleoside reverse transcriptase inhibitor-containing and protease inhibitor-containing regimens using observational databases

OBJECTIVES

To compare the effectiveness of first protease inhibitor (PI)-containing and non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing regimens.

METHODS

Data were analysed from three large HIV patient databases: Apache HIV Insight (APACHE), Target Management Services (TMS) and Clinical Partners (CP). The effectiveness of therapy was the time taken for HIV-1 RNA to fall below detectable levels on first highly active antiretroviral therapy regimen (PI- or NNRTI-containing) and the subsequent time to failure (two consecutive detectable measurements). Comparisons were made using proportional hazards models, adjusting for differences in age, sex, previous reverse transcriptase inhibitor use, calendar year and baseline viral load and CD4 T-cell count.

RESULTS

The type of regimen was not associated with time to undetectable viral load in any of the three databases, all of which had high power to detect a difference. PI-containing regimens were significantly less likely to fail after reaching undetectable viral loads for APACHE and CP patients (relative hazard, 1.7; 95% confidence interval, 1.3--2.1 and relative hazard, 1.6; 95% confidence interval, 1.0--2.5 respectively). These results remained significant after allowing for an unmeasured confounder with moderate effect on risk. No significant association between time to failure and regimen was found for TMS patients, possibly due to low power (67% to detect a relative hazard of 1.5). No difference was found between regimens in the time taken for an increase of > 100 x 10(9)cells/l in CD4 T-cell count. In the APACHE database, those on NNRTI-containing regimens were more likely to have a failing CD4 T-cell response.

CONCLUSIONS

PI-containing regimens have a lower risk of treatment failure than NNRTI-containing regimens.

Are we headed for a resurgence of the HIV epidemic among men who have sex with men?

HIV remains a critical health issue for men who have sex with men (MSM). In the United States, an estimated 365,000 to 535,000 MSM are living with HIV, and 42% of new HIV infections occur in this population. Recent data on sexually transmitted diseases and on sexual behavior indicate the potential for a resurgence in HIV infections among MSM. Outbreaks of gonorrhea and syphilis have been reported in a growing number of cities, and several studies have observed an increase in unprotected anal intercourse among MSM. These increases in HIV risk behavior may be attributed to several factors that have affected the sexual practices of MSM, including changes in beliefs regarding the severity of HIV disease. These emerging data have implications for surveillance and intervention research activities and indicate a need to reevaluate, refocus, and reinvigorate HIV prevention efforts for MSM. Our recommendations for addressing the HIV prevention needs of MSM include the need to consider HIV-related issues within the broader context of the physical, mental, and sexual health of MSM.

HIV in body fluids during primary HIV infection: implications for pathogenesis, treatment and public health

OBJECTIVE

To describe initial viral dissemination to peripheral tissues and infectious body fluids during human primary HIV infection.

DESIGN

Observational cohort study.

METHODS

Blood plasma, cerebrospinal fluid (CSF), seminal plasma, cervicovaginal lavage fluid and/or saliva were sampled from 17 individuals with primary HIV infection (range of time from symptoms onset to sampling, 8--70 days) and one individual with early infection (168 days). Subjects' HIV-1 RNA levels in each fluid were compared with levels from antiretroviral-naive controls with established HIV infection. For study subjects, correlations were assessed between HIV-1 RNA levels and time from symptoms onset. Responses to antiretroviral therapy with didanosine + stavudine + nevirapine +/- hydroxyurea were assessed in each compartment.

RESULTS

HIV-1 RNA levels were highest closest to symptoms onset in blood plasma (18 patients) and saliva (11 patients). CSF HIV-1 RNA levels (five patients) appeared lower closer to symptoms onset, although they were higher overall in primary versus established infection. Shedding into seminal plasma (eight patients) and cervicovaginal fluid (two patients) was established at levels observed in chronic infection within 3--5 weeks of symptoms onset. High-level seminal plasma shedding was associated with coinfection with other sexually transmitted pathogens. Virus replication was suppressed in all compartments by antiretroviral therapy.

CONCLUSIONS

Peak level HIV replication is established in blood, oropharyngeal tissues and genital tract, but potentially not in CSF, by the time patients are commonly diagnosed with primary HIV infection. Antiretroviral therapy is unlikely to limit initial virus spread to most tissue compartments, but may control genital tract shedding and central nervous system expansion in primary infection.

Quantification of in vivo replicative capacity of HIV-1 in different compartments of infected cells

Based on a mathematical model, we analyze the dynamics of CD4+ cells, actively, latently, persistently, and defectively infected cells and plasma virus after initiation of antiretroviral therapy in 14 HIV-1-infected asymptomatic patients. By simultaneous fitting of our model to clinical data of plasma HIV-1 RNA, peripheral blood mononuclear cell (PBMC)-gag RNA, proviral DNA, and CD4+ cell counts, we estimate kinetic parameters to determine the basic reproductive rate (R0) of the virus in different infected cell compartments as a measure of the replicative capacity of the virus in vivo. We find that the basic reproductive rate is larger than 1 before treatment only in actively infected cells (mean R0(act) approximately 2.46) indicating that only in this compartment the virus can maintain an ongoing infection. In latently and persistently infected cells the basic reproductive rate is considerably smaller (R0(lat) approximately 0.03 and R0(pers) approximately 0.008, respectively) indicating that these compartments contribute little to the total basic reproductive rate and cannot maintain an ongoing infection in absence of actively infected cells.

Sex differences in HAART-associated dyslipidaemia

OBJECTIVES

Because female sex protects against dyslipidaemia and atherosclerosis in normal subjects, we aimed to reveal potential sex differences in metabolic side-effects of a newly initiated highly active antiretroviral therapy (HAART) regimen, and to relate these changes to endothelial cell activation as measured by levels of circulating E-selectin (cE-selectin).

DESIGN

Prospective longitudinal cohort study.

SETTING

Tertiary care centre at a University Hospital.

METHODS

HIV-seropositive male (n = 27) and female patients (n = 13) with a plasma viral load of > or = 10 000 copies/ml and 35 healthy controls were enrolled in the study. All participants were weight stable, free of acute opportunistic infections, and had not taken any protease inhibitors before. Serum levels of lipids, insulin, leptin, and cE-selectin were measured before initiation of HAART, and at 3 and 6 months thereafter.

RESULTS

HAART increased serum levels of triglycerides, leptin, and low-density lipoprotein (LDL) cholesterol; these effects were more distinct in women. Fasting insulin levels and the LDL : high density lipoprotein (HDL) ratio increased only in female HIV-infected patients (P < 0.02 versus men). In contrast, endothelial activation, as measured by cE-selectin, decreased more in men (P < 0.02) than in women. As a consequence, women had higher triglycerides and leptin levels after therapy than did men, and the LDL : HDL ratio and cE-selectin levels, which were initially higher in men, were no longer different between the sexes.

CONCLUSIONS

Metabolic adverse effects during HAART are more pronounced in women than in men. Hence, female HIV-infected patients seem to loose part of their natural protection from atherosclerosis during antiretroviral therapy.

Primary and recombinant HIV type 1 strains resistant to protease inhibitors are pathogenic in mature human lymphoid tissues

Preserved peripheral CD4+ T cell counts despite virologic failure in patients undergoing protease inhibitor (PI)-containing antiviral regimens are a frequent occurrence in human immunodeficiency virus (HIV) disease. One hypothesis to explain the relative sparing of CD4+ T cells is that HIV strains exhibiting PI resistance concomitantly are attenuated in terms of cytopathicity for mature T cells. To test this hypothesis, we used a three-dimensional human tonsil histoculture microenvironment to assess the pathogenic potential of a panel of primary and recombinant HIV-1 strains derived from patients experiencing PI failure. All the viruses tested replicated efficiently in these cultures and, in some cases, better than comparable wild-type viral isolates. Furthermore, the PI-resistant strains depleted CD4+ T cells potently and comparably with wild-type isolates in these ex vivo lymphoid tissues. These results demonstrate that PI-resistant viruses are not inherently less pathogenic for mature T cells. Therefore, the sustained peripheral lymphocyte counts in patients with selective virologic failure may be due to specific defects in viral replication in other cell compartments or to an undefined host adaptation to viral infection during PI therapy.

Use of cytokines in human immunodeficiency virus-infected patients: colony-stimulating factors, erythropoietin, and interleukin-2

The recombinant human cytokines granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin, and interleukin-2 (IL-2) have been manufactured and licensed. Studies have been carried out that investigate the use of G-CSF and GM-CSF to reverse leukopenia, as adjunctive therapy for HIV-associated infections and for novel approaches to treat HIV infection, including stem cell mobilization. In addition, studies that identified the role of erythropoietin in the management of anemia have been performed. Furthermore, the abilities of G-CSF and erythropoietin to permit the continued use of marrow suppressive agents that are key in managing HIV infection have been assessed. The aim of this review is to summarize these studies and to describe the reports that evaluate the use of IL-2 to enhance elevation of CD4 cell counts mediated by highly active antiretroviral therapy. This summary is important to the treating clinician in that it identifies the optimal use of these cytokines in current clinical practice as well as their potential future roles.

The potential role of interleukin-2 in HIV

Interleukin-2 (IL-2) is a secretory cytokine produced by activated T cells that stimulates T cells, B cells, and natural killer cells to proliferate and release cytokines. In addition, IL-2 slows apoptosis of HIV-infected cells. Clinical studies have demonstrated that exogenous human recombinant IL-2 can be safely administered concurrently with potent antiretroviral therapy to HIV-infected patients. It was further demonstrated that recombinant human IL-2 therapy produces sustained increases in CD4+ cell number and function in patients with both early and late HIV disease. Further evaluation of the clinical efficacy of IL-2 in HIV-infected patients is expected to provide important information on the utility of recombinant human IL-2 in HIV disease.

Cell-associated HIV-1-DNA quantitation after highly active antiretroviral therapy-treated primary infection in patients with persistently undetectable plasma HIV-1 RNA

OBJECTIVE

To determine the usefulness of cell-associated HIV-1-DNA quantification during the follow-up of highly active antiretroviral therapy (HAART)-treated primary-infected patients with persistently undetectable plasma RNA loads.

PATIENTS AND METHODS

In 27 patients given HAART within a median of 24 days after symptomatic primary HIV infection, plasma and peripheral blood mononuclear cell (PBMC) HIV-1 RNA were less than 50 copies/ml and less than 50 copies/10(6) cells after 18 months of treatment. HIV-1 RNA and DNA were quantified every 6 months in PBMC in these 27 patients, 14 of whom accepted excision lymph node biopsy after month 18 for HIV-1-RNA and -DNA quantification in lymph node mononuclear cells (LNMC).

RESULTS

The median decreases in plasma HIV-1 RNA, PBMC HIV-1 RNA and DNA over the 18 months of follow-up were 3.6 log (P< 0.005), 1.1 log (P< 0.05), and 1.0 log (P<0.001), respectively. HIV-1 DNA was detected in 92.3% of PBMC samples at baseline and at month 18. In LNMC, 100% of samples were detectable for HIV-1 DNA.

CONCLUSION

In this highly selected population of patients with excellent plasma virological response under HAART, HIV-1 DNA showed a progressive decrease but was still detectable in 92.3% of samples at month 18, whereas all LNMC samples tested scored positive for HIV-1 DNA. The utility of proviral HIV-1-DNA monitoring was not clearly demonstrated in this 18-month follow-up of HAART-treated primary-infected patients. However, this finding could be reconsidered when using other therapeutic strategies such as structured treatment interruptions, reinforced treatment or additive immunotherapy.

Anti-HIV activity of a series of cosalane amino acid conjugates

The binding of the anti-HIV agent cosalane to CD4 is thought to involve ionic interactions of negatively charged carboxylates of the ligand with positively charged residues on the surface of the protein. The purpose of the present study was to examine the hypothesis that the two carboxyl groups of cosalane could be sacrificed through conjugation to amino acids, and the anti-HIV activity still be retained, provided that at least two new carboxyl groups are contributed by the amino acid residues.

Identification of optimal anion spacing for anti-HIV activity in a series of cosalane tetracarboxylates

The binding of the anti-HIV agent cosalane to CD4 is thought to involve ionic interactions of negatively charged carboxylates of the ligand with positively charged residues on the surface of the protein. An investigation of the optimal anion distances for anti-HIV activity in a series of cosalane tetracarboxylate analogues has been completed, and maximal activity results when the two proximal and the two distal carboxylates are separated by eight atoms.

Enhanced penetration of indinavir in cerebrospinal fluid and semen after the addition of low-dose ritonavir

OBJECTIVE

Penetration of antiretroviral drugs into anatomical HIV-1 reservoirs such as the male genital tract and the central nervous system is important. Data on indinavir (IDV) concentrations in seminal plasma are lacking and IDV concentrations in cerebrospinal fluid are at best borderline.

DESIGN

Thirteen patients were treated with zidovudine (or stavudine), lamivudine, abacavir, nevirapine and IDV (1000 mg three times daily). When nevirapine led to low IDV concentrations, IDV was changed into the combination IDV/ritonavir (RTV) 800/100 mg twice daily to improve the pharmacokinetic profile of IDV.

METHODS

A serum pharmacokinetic profile, a semen sample and a cerebrospinal fluid sample were collected at weeks 8, 24, 48 and 72.

RESULTS

Addition of RTV increased the median IDV trough concentration in serum from 65 to 336 ng/ml (P = 0.005). Median IDV concentration in seminal plasma increased from 141 to 1634 ng/ml (P = 0.002) (n = 9) and in cerebrospinal fluid from 39 (n = 12) to 104 (n = 7) ng/ml (P < 0.001). In six patients with samples collected both before and after the addition of RTV, the IDV concentration in seminal plasma increased 8.2 times [95% confidence interval (CI) 5.2-11.6], and in cerebrospinal fluid 2.4 times (95% CI 1.8-3.9).

CONCLUSIONS

IDV penetrates well into the male genital tract. The addition of low-dose RTV not only increases IDV concentrations in serum but also in seminal plasma and cerebrospinal fluid, thereby probably improving the potency of the regimen in these anatomical HIV reservoirs. Higher serum trough levels alone can not sufficiently explain the observed increases in seminal plasma and cerebrospinal fluid concentrations. Inhibition of P-glycoprotein-mediated transport by RTV might be an additional mechanism.