Cerebral microsporidiosis manifesting as progressive multifocal leukoencephalopathy in an HIV-infected individual - a case report.

Microsporidia have become increasingly recognized as opportunistic pathogens since the genesis of the AIDS epidemic. The incidence of microsporidiosis has decreased with the advent of combination antiretroviral therapy but it is frequently reported in non-HIV immunosuppressed patients and as a latent infection in immunocompetent individuals. Herein, we describe an HIV-infected male (46 years) with suspected progressive multifocal leukoencephalopathy that has not responded to optimal antiretroviral therapy, steroids, or cidofovir. Post-mortem examination revealed cerebral microsporidiosis. No diagnostic clue however, was found when the patient was alive. This report underscores the need for physicians to consider microsporidiosis (potentially affecting the brain) when no other etiology is established both in HIV, non-HIV immunosuppressed patients and in immunocompetent individuals.

Dynamics and consequences of IL-21 production in HIV-infected individuals: a longitudinal and cross-sectional study.

IL-21 is a relatively newly discovered immune-enhancing cytokine that plays an essential role in controlling chronic viral infections. It is produced mainly by CD4(+) T cells, which are also the main targets of HIV-1 and are often depleted in HIV-infected individuals. Therefore, we sought to determine the dynamics of IL-21 production and its potential consequences for the survival of CD4(+) T cells and frequencies of HIV-specific CTL. For this purpose, we conducted a series of cross-sectional and longitudinal studies on different groups of HIV-infected patients and show in this study that the cytokine production is compromised early in the course of the infection. The serum cytokine concentrations correlate with CD4(+) T cell counts in the infected persons. Among different groups of HIV-infected individuals, only elite controllers maintain normal production of the cytokine. Highly active antiretroviral therapy only partially restores the production of this cytokine. Interestingly, HIV infection of human CD4(+) T cells inhibits cytokine production by decreasing the expression of c-Maf in virus-infected cells, not in uninfected bystander cells. We also show that the frequencies of IL-21-producing HIV-specific, but not human CMV-specific, Ag-experienced CD4(+) T cells are decreased in HIV-infected viremic patients. Furthermore, we demonstrate in this study that recombinant human IL-21 prevents enhanced spontaneous ex vivo death of CD4(+) T cells from HIV-infected patients. Together, our results suggest that serum IL-21 concentrations may serve as a useful biomarker for monitoring HIV disease progression and the cytokine may be considered for immunotherapy in HIV-infected patients.

Combination antiretroviral therapy and chronic HIV infection affect serum retinoid concentrations: longitudinal and cross-sectional assessments.

BACKGROUND: Several lines of evidence suggest that retinoids (retinol-ROL or vitamin A, and its active metabolites, retinoic acids-RAs) play important pathogenic roles in HIV infection and combination antiretroviral therapy (cART)-related events. We previously reported that antiretrovirals alter RAs synthesis in vitro. We hypothesised that in vivo serum retinoid concentrations are affected by both cART and HIV infection. This might explain several clinical and laboratory abnormalities reported in HIV-infected patients receiving cART. METHODS: The effects of optimal cART and chronic HIV on serum retinoids were firstly assessed longitudinally in 10 HIV-infected adults (group1 = G1): twice while on optimal cART (first, during long-term and second, during short term cART) and twice during 2 cART interruptions when HIV viral load (VL) was detectable. Retinoid concentrations during optimal long term cART in G1 were compared with cross-sectional results from 12 patients (G2) with suboptimal cART (detectable VL) and from 28 healthy adults (G3). Serum retinoids were measured by HPLC with ultraviolet detection. Retinoid concentrations were correlated with VL, CD4+ T- cell count and percentages, CD8+38+ fluorescence, triglycerides, cholesterol and C-peptide serum levels. RESULTS: During optimal cART, G1 participants had drastically reduced RAs (0.5 ± 0.3 µg/dL; P < 0.01) but the highest ROL (82 ± 3.0 µg/dL) concentrations. During cART interruptions in these patients, RAs slightly increased whereas ROL levels diminished significantly (P < 0.05). G3 had the highest RAs levels (7.2 ± 1.1 µg/dL) and serum ROL comparable to values in North Americans. Serum ROL was decreased in G2 (37.7 ± 3.2 µg/dL; P < 0.01). No correlations were noted between RA and ROL levels or between retinoid concentrations and CD4+ T- cell count, CD8+38+ fluorescence, VL. ROL correlated with triglycerides and cholesterol in G1 (rs = 0.8; P = 0.01). CONCLUSIONS: Serum RAs levels are significantly diminished by cART, whereas ROL concentrations significantly decreased during uncontrolled HIV infection but augmented with optimal cART. These alterations in retinoid concentrations may affect the expression of retinoid-responsive genes involved in metabolic, hormonal and immune processes and be responsible for some adverse events observed in HIV-infected persons treated with antiretrovirals. Further studies should assess concomitant serum and intracellular retinoid levels in different clinical situations in larger, homogenous populations.

HIV-1 causes an imbalance in the production of interleukin-18 and its natural antagonist in HIV-infected individuals: implications for enhanced viral replication.

BACKGROUND: Concentrations of interleukin (IL)-18 increase in the circulation of human immunodeficiency virus (HIV)-infected persons. However, nothing is known concerning the regulation of IL-18-binding protein (IL-18BP), which neutralizes IL-18 in vivo. This issue is addressed in the present study. METHODS: Serum samples obtained from healthy subjects and HIV-infected patients were analyzed by enzyme-linked immunosorbent assay to determine their IL-18 and IL-18BP contents. Human monocyte-derived macrophages (MDMs) were infected in vitro with HIV type 1 (HIV-1), and the production of these 2 cytokines by these cells was measured. Finally, we determined the effect of IL-18 on HIV-1 replication in human cells. RESULTS: In contrast to IL-18 levels, IL-18BP levels decreased in the serum of HIV-infected patients. This decrease resulted in enhanced levels of free IL-18 in the serum of such patients. The infection increased production of IL-18 but decreased that of IL-18BP in MDMs. IL-10 and transforming growth factor-beta, concentrations of which are increased in HIV-infected persons, also decreased production of IL-18BP by human MDMs. Finally, recombinant human IL-18 enhanced HIV-1 replication in human CD4(+) T cells. CONCLUSIONS: Production of IL-18 and its antagonist becomes imbalanced in HIV-1-infected persons. The infection and the cytokine milieu play a role in this decreased production. The increased biological activities of IL-18 may enhance viral replication in human CD4(+) T cells.

Potential role of interleukin-18 in the immunopathogenesis of AIDS: involvement in fratricidal killing of NK cells.

We had shown earlier that the concentrations of circulating interleukin-18 (IL-18) are increased significantly in human immunodeficiency virus (HIV)-infected persons compared to HIV-seronegative healthy subjects. In the present study, we investigated the consequences of these elevated levels of IL-18 on natural killer (NK) cells and the immunopathogenesis of AIDS. We show here an inverse correlation between IL-18 concentrations and absolute numbers of various subsets of NK cells in infected persons. Recombinant human IL-18 caused increased death of a human NK cell line, as well as of primary human NK cells in vitro. The IL-18-mediated cell death was dependent upon Fas-FasL interactions and tumor necrosis factor alpha. IL-18 induced the expression of FasL on NK cells, increased the transcription from the human FasL promoter, reduced the expression of Bcl-X(L) in NK cells, and increased their sensitivity to FasL-mediated cell death. These results suggest that increased IL-18 concentrations present in the circulation of HIV-infected persons contribute to the immunopathogenesis of AIDS by altering NK cell homeostasis.

Predictive value of immune parameters before treatment interruption (TI) for CD4+ T-cell count change during TI in HIV infection.

BACKGROUND: Despite the contraindications, stopping treatment for HIV infection continues to be a common practice. Understanding whether T-cell proliferative capacity and phenotypic markers before treatment interruption (TI) can predict CD4+ T-cell count change and nadir during TI would be clinically useful. METHODS: This retrospective study included 27 HIV-infected patients in the chronic phase of infection while on combination antiretroviral therapy (cART) who underwent a TI. Peripheral blood mononuclear cells from a baseline pre-TI time point were screened for T-cell proliferation to cytomegalovirus (CMV) lysate, an HIV Gag p55 peptide pool as well as positive and negative control stimuli. CD28 and CD57 expression on CD4+ and CD8+ T-cells were measured. RESULTS: Baseline viral load, CD4+ T-cell count, pre-cART nadir CD4+ T-cell and percentage CD4+CD28+ T-cells were all predictive of the lowest CD4+ T-cell count during TI (Spearman's correlation P<0.05 for all analyses). In addition, CD4+ and CD8+ T-cells proliferation to CMV lysate, baseline CD4+ T-cell count and percentage CD4+CD57+ T-cells correlated negatively with CD4+ T-cell decrease during TI (Spearman's correlation P<0.05 for all analyses). CONCLUSIONS: In treated chronic HIV-infected patients, pre-TI immune parameters are potential predictors for both the nadir CD4+ T-cell count and CD4+ T-cell count decrease during TI.

Longitudinal changes in HIV-specific IFN-gamma secretion in subjects who received Remune vaccination prior to treatment interruption.

BACKGROUND: Despite the benefits of highly active antiretroviral therapy (HAART) for suppressing viral replication in HIV infection, virus persists and rebounds during treatment interruption (TI). This study explored whether HAART intensification with Remune vaccination before TI can boost HIV-1-specific immunity, leading to improved control of viremia off HAART. METHODS: Ten chronically HIV-infected adults were enrolled in this proof of concept study. After a 6-month HAART intensification phase with didanosine, hydroxyurea, granulocyte-macrophage colony-stimulating factor, (GM-CSF), and a first dose of Remune (HIV-1 Immunogen), HAART was discontinued. Patients continued to receive Remune every 3 months until the end of study. HAART was restarted if viral load did not fall below 50,000 copies/ml of plasma within 3 months or if CD4+ counts decreased to <200 cells/mm3. HIV-specific immunity was monitored with the interferon-gamma (IFN-gamma) ELISPOT assay. RESULTS: All subjects experienced viral rebound during TIs. Although the magnitude and breadth of HIV-specific responses to HLA-restricted optimal peptide panels and Gag p55 peptide pools increased and viral load decreased by 0.44 log10 units from TI#1 to TI#2, no significant correlations between these parameters were observed. The patients spent 50.4% of their 36 months follow up off HAART. CONCLUSION: Stopping HAART in this vaccinated population induced immune responses that persisted after therapy was restarted. Induction of HIV-specific immunity beyond IFN-gamma secretion may be contributing to better control of viremia during subsequent TIs allowing for long periods off HAART.

Treatment options for progressive multifocal leukoencephalopathy in HIV-infected persons: current status and future directions.

Progressive multifocal encephalopathy (PML) caused by JC virus was frequently encountered in AIDS patients before combination antiretroviral therapy (cART). Incidence decreased and the outcome improved with cART. The immune reconstitution with cART is beneficial for HIV-infected patients and is an effective treatment for PML. However, when it is excessive an inflammatory response immune syndrome might occur with deterioration of PML. So far, no specific therapy has proven efficacious in small clinical trials in spite of some optimistic case reports. Combination of drugs targeted at different stages of JC virus life cycle seems to have a better effect. Passive and active immune therapies, immune competence "boosters" appear promising. New future approaches such as gene editing are not far away.

IL-15 and HIV infection: lessons for immunotherapy and vaccination.

IL-15 is a pleiotropic and multifunctional cytokine that has a diverse array of distinct biological effects in the body. It plays a crucial role in host defense from viral and non-viral intracellular pathogens. The cytokine is essential for the development and differentiation of NK cells and for homeostatic expansion of CD8+ memory T cells, NKT cells and certain subsets of intestinal intra-epithelial lymphocytes (iIEL). It acts as a survival factor and inhibits spontaneous apoptosis in T, B and NK cells by increasing expression of different anti-apoptotic proteins. Several studies have shown that IL-15 production is compromised in HIV-infected AIDS patients and exogenous IL-15 drastically enhances functions of immune cells from these patients. Considering these distinct immune enhancing effects, relative safety in animal models, and minimal effects on HIV replication, IL-15 may represent a better cytokine for immune reconstitution in these patients. Furthermore, IL-15 may also act as a better adjuvant in eliciting antiviral immunity in anti-HIV vaccine strategies.

Successful discontinuation of therapy for disseminated Mycobacterium avium complex infection after effective antiretroviral therapy.

BACKGROUND: Highly active antiretroviral therapy (HAART) is associated with improvement or resolution of several HIV-associated opportunistic infections. Although prophylaxis against disseminated Mycobacterium avium complex infection may be successfully discontinued after a favorable response to HAART, the 1999 guidelines from the U.S. Public Health Service/Infectious Diseases Society of America recommend continuing therapy for disseminated M. avium complex infection, regardless of the response to HAART. OBJECTIVE: To examine the outcome among patients with disseminated M. avium complex infection whose antimycobacterial therapy was discontinued after a favorable response to HAART. DESIGN: Retrospective chart review between May 2000 and May 2001. SETTING: 13 Canadian HIV clinics. PATIENTS: 52 HIV-infected adults (43 men; mean age, 37.3 years) in whom successful antimycobacterial therapy for disseminated M. avium complex infection was discontinued after a favorable virologic response to HAART. MEASUREMENTS: Survival, survival free of disseminated M. avium complex infection, and CD4(+) cell count responses. RESULTS: At the time of diagnosis of disseminated M. avium complex infection, the median CD4(+) cell count was 0.016 x 10(9) cells/L, and the median plasma HIV RNA level was 90 000 copies/mL (plasma HIV RNA levels were available for only 21 patients). The patients received a median of 32 months of antimycobacterial therapy that included ethambutol plus either clarithromycin or azithromycin. When antimycobacterial therapy was discontinued, the median CD4(+) cell count was 0.23 x 10(9) cells/L and the median plasma HIV RNA level was less than 50 copies/mL. A median of 20 months after discontinuation of antimycobacterial therapy, only 1 patient had developed recurrent M. avium complex disease (37 months after stopping antimycobacterial therapy). This patient had stopped HAART 2 months earlier because of uncontrolled HIV viremia. Twenty months after stopping antimycobacterial therapy, the other 51 patients had a median CD4(+) cell count of 0.288 x 10(9) cells/L; 34 (67%) had undetectable plasma HIV RNA levels, and 8 (15%) had plasma HIV RNA levels of 50 to 1000 copies/mL. CONCLUSIONS: Discontinuation of successful disseminated M. avium complex therapy after a successful response to HAART is safe and reduces patients' pill burdens, potential drug adverse effects, drug interactions, and costs of therapy.

Immunogenicity and tolerability of an inactivated and adjuvanted pandemic H1N1 influenza vaccine, in HIV-1-infected patients.

We evaluated the efficacy and tolerability of a single dose of the split virion AS03-adjuvanted pandemic H1N1 influenza vaccine (A/California/7/2009) in 84 HIV-1 infected individuals. Antibody titers were determined by hemagglutination inhibition assay and by microneutralization. Vaccine was well tolerated. At 21 days post vaccination, 56 (67%) patients had seroconverted. There was no correlation between baseline CD4 cell count (p=0.539) or HIV viral load (p=0.381) and immune response. Other vaccine strategies should be evaluated in this HIV population, to improve response rates.

IL-21 enhances NK cell functions and survival in healthy and HIV-infected patients with minimal stimulation of viral replication.

IL-21 plays an important role in regulating immune response and controlling chronic viral infections. Recently, we reported its decreased serum concentrations and their immunological consequences in HIV-infected persons. In this study, we have investigated how exogenous IL-21 enhances NK cell responses in these persons. We show that the cytokine receptors are expressed equally on all NK cell subsets defined by expression of CD16 and CD56; the cytokine activates STAT-3, MAPK, and Akt to enhance NK cell functions; the STAT-3 activation plays a key role in constitutive and IL-21-mediated enhancement of NK cell functions; the cytokine increases expression of antiapoptotic proteins Bcl-2 and Bcl-X(L) and enhances viability of NK cells but has no effect on their proliferation; the cytokine enhances HIV-specific ADCC, secretory, and cytotoxic functions, as well as viability of NK cells from HIV-infected persons; it exerts its biological effects on NK cells with minimal stimulation of HIV-1 replication; and the cytokine-activated NK cells inhibit viral replication in cocultured, HIV-infected, autologous CD4(+) T cells in a perforin- and LFA-1-dependent manner. These data suggest that IL-21 may serve as a valuable therapeutic tool for enhancing NK cell responses and inhibiting viral replication in HIV-infected patients.

Potential role of IL-18 in the immunopathogenesis of AIDS, HIV-associated lipodystrophy and related clinical conditions.

IL-18 is a pleiotropic and multifunctional proinflammatory cytokine that is often produced in response to a viral infection. The biological activities of the cytokine are tightly controlled by its natural antagonist, IL-18 binding protein (IL-18BP), as well as by activation of caspase-1, which cleaves the precursor form of IL-18 into its biologically mature form. The cytokine plays an important role in both innate and adaptive antiviral immune responses. Depending upon the context, it can promote TH1, TH2 and TH17 responses. Increased serum concentrations of IL-18 and concomitantly decreased concentrations of its natural antagonist have been described in HIV-infected persons as compared to HIV-seronegative healthy subjects. We discuss in this review article how increased biological activities of IL-18 contribute towards immunopathogenesis of AIDS, HIV-associated lipodystrophy syndrome and related metabolic disturbances. While the advent of potent anti-HIV drugs has significantly enhanced life span of HIV-infected patients, it has also increased the number of these patients suffering from metabolic disorders. The cytokine may prove to be a useful target for therapeutic intervention in these patients.

Role of interleukin-18 in the development and pathogenesis of AIDS.

Interleukin-18 is a proinflammatory, proapoptotic, and proatherogenic cytokine belonging to the interleukin-1 family of cytokines. The cytokine exerts many unique immunologic and biological effects. It is produced as a biologically inactive and leaderless precursor protein, which must be cleaved into its mature form by caspase-1. The caspase-1 also exists in an inactive precursor in the cytosol and needs proteolytic auto-cleavage, which is catalyzed by the assembly of a multi-protein complex called inflammasome. Inside the circulation, interleukin-18 is bound to its naturally occurring antagonist called interleukin-18 binding protein. The antagonist is induced as a negative feedback to increased interleukin-18 production. It protects body cells and tissues from the potentially destructive and harmful proinflammatory effects of the cytokine. Several researchers have reported that the concentrations and biological activities of the cytokine are increased in the circulation of HIV-infected patients. Unlike interleukin-18, the concentrations of its antagonist, interleukin-18 binding protein, are decreased in these persons. The cytokine may play a major role in the development and pathogenesis of AIDS in HIV-infected persons. Insufficient/lack of interleukin-12 and related cytokines may compromise the ability of interleukin-18 to induce interferon-gamma production from natural killer and T-cells. By inducing production of T-helper 2-type cytokines like interleukin-4, -5, -9, and -13 from basophils and mast cells, interleukin-18 promotes the development and differentiation of CD4+ naive T-cells into T-helper 2-type effector cells, which blunt anti-HIV immunity. The effect may be more pronounced in HIV-infected persons with compromised production of interleukin-12. Interleukin-18 also directly enhances viral replication. Because of its proapoptotic effects, the cytokine decreases survivability and promotes the death of various immune and nonimmune cells. It has also been documented to play a role in the depletion and wasting of subcutaneous fat from the limbs and face. The wasting is a characteristic feature of HIV-associated lipodystrophy. The cytokine is also likely to be involved in the higher incidence of atherosclerotic plaques and systemic insulin resistance in these patients. Finally, increased production of the cytokine in the brain may lead to motor and cognitive dysfunctions, leading to the development of HIV-associated dementia. In conclusion, increased interleukin-18 concentrations in HIV-infected persons are likely to play an important role in the development and progression of the infection toward AIDS and associated clinical conditions. Therefore, its neutralization may represent an appropriate and useful immunotherapeutic strategy in these patients. It may delay AIDS progression and improve the immune status of infected persons. The best way to achieve this goal may be using exogenous interleukin-18 binding protein.

Decreased levels of circulating IL-21 in HIV-infected AIDS patients: correlation with CD4+ T-cell counts.

IL-21 is a relatively newly discovered multifunctional and pleiotropic cytokine. It is produced primarily by CD4(+) T cells, the principal targets of the virus, and therefore this cytokine has special relevance to HIV infection. Here we show for the first time that serum levels of this cytokine are significantly reduced in HIV-infected AIDS patients and correlate significantly with their CD4(+) T-cell counts. These data suggest that the cytokine levels could act as a valuable biomarker for the progression of AIDS.

Relationship of in vivo and ex vivo levels of TH1 and TH2 cytokines with viremia in HAART patients with and without opportunistic infections.

TH1/TH2 cytokines' imbalance is critical to HIV-1 progression and pathogenesis. Opportunistic infections-related cytokine perturbations in the setting of highly active antiretroviral therapy (HAART) are unclear. The objective of this cross-sectional study was to identify the relationship between TH1/TH2 cytokines and viremia in HAART patients with/without opportunistic infections. Sera from 17 HAART patients with and 43 without opportunistic infections, and 20 HIV-seronegative controls were used to measure the levels of IL-2, IFN-gamma, IL-4, and IL-10 proteins and mRNAs by ELISA and RNase protection assays, respectively. Ex vivo cytokine production by the CD4+/CD8+ T cells from four low and four high viremia patients randomly selected from non-opportunistic infection group was also evaluated. Serum IL-2 and IFN-gamma levels were lower (P < 0.05) in patients than controls; this reduction was more pronounced for IFN-gamma in non-opportunistic infection patients. IL-4 and IL-10 were higher in patients than controls; this elevation was more remarkable in patients with opportunistic infections. Serum TH1/TH2 cytokine levels correlated with viremia. In vitro cytokine production assays showed that CD4+ T cells from low viremia patients mainly produced IL-2 and IFN-gamma, CD8+ T cells from high viremia patients produced IL-4, and both subsets comparably produced IL-10 in patients with similar viremia. Positive correlations between sera/supernatant proteins and cellular mRNAs were also found statistically significant (P < 0.05). It was therefore concluded that in vivo TH1/TH2 cytokine levels in HAART patients and their ex vivo production by the CD4+/CD8+ T cells correlated with viremia and were also modulated by the presence of opportunistic infections in these patients.

Effects of different types of exercise on body composition and fat distribution in HIV-infected patients: a brief review.

HIV infection and its treatment is associated with unfavourable metabolic and morphological abnormalities. These metabolic abnormalities, particularly alterations in body composition and fat distribution, may increase the risk for cardiovascular and metabolic complications, as well as reduce functional independence and lower self-esteem. Thus there is an urgent need to develop interventions intended to manage secondary side effects of HIV or antiretroviral therapy-related complications. In poly-treated patients, nonpharmacological interventions are a logical first step. Exercise training in particular may help alleviate some of the metabolic adverse effects associated with antiretroviral therapy by favourably altering body composition and patterns of body fat distribution. Studies have shown that exercise training, particularly aerobic training, can help reduce total body and visceral fat, as well as normalizing lipid profiles in HIV-infected patients. The results for resistance training, however, are less conclusive. Knowledge of the use of resistance and aerobic training and its attendant effects on insulin resistance and adipocytokines may represent an effective nonpharmacologic means for treating metabolic complications of HIV-infected persons who are receiving appropriate antiretroviral therapy. In this brief review we examine the effects of aerobic and resistance training on body composition, body fat distribution, and selected metabolic outcomes.