Immune reconstitution inflammatory syndrome in patients starting antiretroviral therapy for HIV infection: a systematic review and meta-analysis

In patients with HIV-1 infection who are starting combination antiretroviral therapy (ART), the incidence of immune reconstitution inflammatory syndrome (IRIS) is not well defined. We did a meta-analysis to establish the incidence and lethality of the syndrome in patients with a range of previously diagnosed opportunistic infections, and examined the relation between occurrence and the degree of immunodeficiency. Systematic review identified 54 cohort studies of 13 103 patients starting ART, of whom 1699 developed IRIS. We calculated pooled cumulative incidences with 95% credibility intervals (CrI) by Bayesian methods and did a random-effects metaregression to analyse the relation between CD4 cell count and incidence of IRIS. In patients with previously diagnosed AIDS-defining illnesses, IRIS developed in 37.7% (95% CrI 26.6-49.4) of those with cytomegalovirus retinitis, 19.5% (6.7-44.8) of those with cryptococcal meningitis, 15.7% (9.7-24.5) of those with tuberculosis, 16.7% (2.3-50.7) of those with progressive multifocal leukoencephalopathy, and 6.4% (1.2-24.7) of those with Kaposi's sarcoma, and 12.2% (6.8-19.6) of those with herpes zoster. 16.1% (11.1-22.9) of unselected patients starting ART developed any type of IRIS. 4.5% (2.1-8.6) of patients with any type of IRIS died, 3.2% (0.7-9.2) of those with tuberculosis-associated IRIS died, and 20.8% (5.0-52.7) of those with cryptococcal meningitis died. Metaregression analyses showed that the risk of IRIS is associated with CD4 cell count at the start of ART, with a high risk in patients with fewer than 50 cells per microL. Occurrence of IRIS might therefore be reduced by initiation of ART before immunodeficiency becomes advanced.

Morbidity and aging in HIV-infected persons: the Swiss HIV cohort study

Patterns of morbidity and mortality among human immunodeficiency virus (HIV)-infected individuals taking antiretroviral therapy are changing as a result of immune reconstitution and improved survival. We studied the influence of aging on the epidemiology of non-AIDS diseases in the Swiss HIV Cohort Study.

Impact of antiretroviral therapy on tuberculosis incidence among HIV-positive patients in high-income countries

The lower tuberculosis incidence reported in human immunodeficiency virus (HIV)-positive individuals receiving combined antiretroviral therapy (cART) is difficult to interpret causally. Furthermore, the role of unmasking immune reconstitution inflammatory syndrome (IRIS) is unclear. We aim to estimate the effect of cART on tuberculosis incidence in HIV-positive individuals in high-income countries.

Late presentation of HIV-infected individuals

Late presentation remains a major concern despite the dramatically improved prognosis realized by ART. We define a first presentation for HIV care during the course of HIV infection as 'late' if an AIDS-defining opportunistic disease is apparent, or if CD4+ T-cells are <200/microl. In the Western world, approximately 10 and 30% of HIV-infected individuals still present with CD4+ T-cells <50 and <200/microl, respectively; estimates are substantially higher for developing countries. Diagnosis and treatment of opportunistic diseases and intense supportive in-hospital care take precedence over ART. Benefits of starting ART without delay, that is, when opportunistic diseases are still active, include faster resolution of opportunistic diseases and a decreased risk of recurrence. The downside of starting ART without delay could include toxicity, drug interactions and immune reconstitution inflammatory syndrome (IRIS). Among asymptomatic or oligosymptomatic individuals presenting late, where ART and primary prophylaxis are initiated, approximately 10-20% will become symptomatic from drug toxicity or undiagnosed opportunistic complications, including IRIS, which require appropriate therapies. In this review we describe late presentation to HIV care, the scale of the problem, the evaluation of a late-presenting patient and challenges associated with initiation of potent antiretroviral therapy (ART) in the setting of acute opportunistic infections and other comorbidities.

Liver enzyme elevation after lamivudine withdrawal in HIV-hepatitis B virus co-infected patients: the Swiss HIV Cohort Study

Background The principal causes of liver enzyme elevation among HIV-hepatitis B virus (HBV) co-infected patients are the hepatotoxic effects of antiretroviral therapy (ART), alcohol abuse, ART-induced immune reconstitution and the exacerbation of chronic HBV infection. Objectives To investigate the incidence and severity of liver enzyme elevation, liver failure and death following lamivudine (3TC) withdrawal in HIV-HBV co-infected patients. Methods Retrospective analysis of the Swiss HIV Cohort Study database to assess the clinical and biological consequences of the discontinuation of 3TC. Variables considered for analysis included liver enzyme, HIV virological and immunological parameters, and medication prescribed during a 6-month period following 3TC withdrawal. Results 3TC was discontinued in 255 patients on 363 occasions. On 147 occasions (109 patients), a follow-up visit within 6 months following 3TC withdrawal was recorded. Among these patients, liver enzyme elevation occurred on 42 occasions (29%), three of them (2%) with severity grade III and five of them (3.4%) with severity grade IV elevations (as defined by the AIDS Clinical Trials Group). Three patients presented with fulminant hepatitis. One death (0.7%) was recorded. Conclusions HBV reactivation leading to liver dysfunction may be an under-reported consequence of 3TC withdrawal in HIV-HBV co-infected patients. Regular monitoring of HBV markers is warranted if active therapy against HBV is discontinued.

Gene therapy for immunodeficiency due to adenosine deaminase deficiency

BACKGROUND: We investigated the long-term outcome of gene therapy for severe combined immunodeficiency (SCID) due to the lack of adenosine deaminase (ADA), a fatal disorder of purine metabolism and immunodeficiency. METHODS: We infused autologous CD34+ bone marrow cells transduced with a retroviral vector containing the ADA gene into 10 children with SCID due to ADA deficiency who lacked an HLA-identical sibling donor, after nonmyeloablative conditioning with busulfan. Enzyme-replacement therapy was not given after infusion of the cells. RESULTS: All patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transduced hematopoietic stem cells have stably engrafted and differentiated into myeloid cells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%) and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patients do not require enzyme-replacement therapy, their blood cells continue to express ADA, and they have no signs of defective detoxification of purine metabolites. Nine patients had immune reconstitution with increases in T-cell counts (median count at 3 years, 1.07x10(9) per liter) and normalization of T-cell function. In the five patients in whom intravenous immune globulin replacement was discontinued, antigen-specific antibody responses were elicited after exposure to vaccines or viral antigens. Effective protection against infections and improvement in physical development made a normal lifestyle possible. Serious adverse events included prolonged neutropenia (in two patients), hypertension (in one), central-venous-catheter-related infections (in two), Epstein-Barr virus reactivation (in one), and autoimmune hepatitis (in one). CONCLUSIONS: Gene therapy, combined with reduced-intensity conditioning, is a safe and effective treatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers, NCT00598481 and NCT00599781.)

The Incidence of AIDS-Defining Illnesses at a Current CD4 Count >=200 Cells/ L in the Post-Combination Antiretroviral Therapy Era

Background. Few studies consider the incidence of individual AIDS-defining illnesses (ADIs) at higher CD4 counts, relevant on a population level for monitoring and resource allocation. Methods. Individuals from the Collaboration of Observational HIV Epidemiological Research Europe (COHERE) aged ≥14 years with ≥1 CD4 count of ≥200 µL between 1998 and 2010 were included. Incidence rates (per 1000 person-years of follow-up [PYFU]) were calculated for each ADI within different CD4 strata; Poisson regression, using generalized estimating equations and robust standard errors, was used to model rates of ADIs with current CD4 ≥500/µL. Results. A total of 12 135 ADIs occurred at a CD4 count of ≥200 cells/µL among 207 539 persons with 1 154 803 PYFU. Incidence rates declined from 20.5 per 1000 PYFU (95% confidence interval [CI], 20.0–21.1 per 1000 PYFU) with current CD4 200–349 cells/µL to 4.1 per 1000 PYFU (95% CI, 3.6–4.6 per 1000 PYFU) with current CD4 ≥ 1000 cells/µL. Persons with a current CD4 of 500–749 cells/µL had a significantly higher rate of ADIs (adjusted incidence rate ratio [aIRR], 1.20; 95% CI, 1.10–1.32), whereas those with a current CD4 of ≥1000 cells/µL had a similar rate (aIRR, 0.92; 95% CI, .79–1.07), compared to a current CD4 of 750–999 cells/µL. Results were consistent in persons with high or low viral load. Findings were stronger for malignant ADIs (aIRR, 1.52; 95% CI, 1.25–1.86) than for nonmalignant ADIs (aIRR, 1.12; 95% CI, 1.01–1.25), comparing persons with a current CD4 of 500–749 cells/µL to 750–999 cells/µL. Discussion. The incidence of ADIs was higher in individuals with a current CD4 count of 500–749 cells/µL compared to those with a CD4 count of 750–999 cells/µL, but did not decrease further at higher CD4 counts. Results were similar in patients virologically suppressed on combination antiretroviral therapy, suggesting that immune reconstitution is not complete until the CD4 increases to >750 cells/µL.

Antiretrovirale Therapie

Antiretroviral therapy to treat HIV, as we know it today, is nothing less than a huge success story in modern medical history. What used to be an almost certain death-sentence was transformed into a very manageable chronic disease by means of highly efficient und mostly well tolerated drugs. Today, HIV-infected patients treated according to international recommendations have a very good chance to outgo the negative effects of HIV-1 and are therefore able to reach an almost normal life expectancy. Furthermore, patients successfully treated with antiretroviral drugs are no longer infectious, which is an essential aspect of global strategies to overcome the pandemic. Nevertheless, due to the complexity of HIV, physicians treating patients with antiretroviral therapy require profound knowledge of aspects such as viral resistance mechanisms and immune reconstitution, as well as drug-toxicity und drug-drug-interactions. Many other aspects such as long-term side-effects of antiretroviral drugs are still unknown. Strict adherence to treatment is of utmost importance.

Indigenous enteric eosinophils control DCs to initiate a primary Th2 immune response in vivo.

Eosinophils natively inhabit the small intestine, but a functional role for them there has remained elusive. Here, we show that eosinophil-deficient mice were protected from induction of Th2-mediated peanut food allergy and anaphylaxis, and Th2 priming was restored by reconstitution with il4(+/+) or il4(-/-) eosinophils. Eosinophils controlled CD103(+) dendritic cell (DC) activation and migration from the intestine to draining lymph nodes, events necessary for Th2 priming. Eosinophil activation in vitro and in vivo led to degranulation of eosinophil peroxidase, a granule protein whose enzymatic activity promoted DC activation in mice and humans in vitro, and intestinal and extraintestinal mouse DC activation and mobilization to lymph nodes in vivo. Further, eosinophil peroxidase enhanced responses to ovalbumin seen after immunization. Thus, eosinophils can be critical contributors to the intestinal immune system, and granule-mediated shaping of DC responses can promote both intestinal and extraintestinal adaptive immunity.

Reversible microbial colonization of germ-free mice reveals the dynamics of IgA immune responses

The lower intestine of adult mammals is densely colonized with nonpathogenic (commensal) microbes. Gut bacteria induce protective immune responses, which ensure host-microbial mutualism. The continuous presence of commensal intestinal bacteria has made it difficult to study mucosal immune dynamics. Here, we report a reversible germ-free colonization system in mice that is independent of diet or antibiotic manipulation. A slow (more than 14 days) onset of a long-lived (half-life over 16 weeks), highly specific anticommensal immunoglobulin A (IgA) response in germ-free mice was observed. Ongoing commensal exposure in colonized mice rapidly abrogated this response. Sequential doses lacked a classical prime-boost effect seen in systemic vaccination, but specific IgA induction occurred as a stepwise response to current bacterial exposure, such that the antibody repertoire matched the existing commensal content.

A comparison of acute and long-term effects of industrial multiwalled carbon nanotubes on human lung and immune cells in vitro

The close resemblance of carbon nanotubes to asbestos fibers regarding their high aspect ratio, biopersistence and reactivity increases public concerns on the widespread use of these materials. The purpose of this study was not only to address the acute adverse effects of industrially produced multiwalled carbon nanotubes (MWCNTs) on human lung and immune cells in vitro but also to further understand if their accumulation and biopersistence leads to long-term consequences or induces adaptive changes in these cells. In contrast to asbestos fibers, pristine MWCNTs did not induce overt cell death in A549 lung epithelial cells and Jurkat T lymphocytes after acute exposure to high doses of this material (up to 30 g/ml). Nevertheless, very high levels of reactive oxygen species (ROS) and decreased metabolic activity were observed which might affect long-term viability of these cells. However, the continuous presence of low amounts of MWCNTs (0.5 g/ml) for 6 months did not have major adverse long-term effects although large amounts of nanotubes accumulated at least in A549 cells. Moreover, MWCNTs did not appear to induce adaptive mechanisms against particle stress in long-term treated A549 cells. Our study demonstrates that despite the high potential for ROS formation, pristine MWCNTs can accumulate and persist within cells without having major long-term consequences or inducing adaptive mechanisms.

Cellular immune responses to HCV core increase and HCV RNA levels decrease during successful antiretroviral therapy

Background Hepatitis C virus (HCV) infection is a major cause of morbidity in HIV infected individuals. Coinfection with HIV is associated with diminished HCV-specific immune responses and higher HCV RNA levels. Aims To investigate whether long-term combination antiretroviral therapy (cART) restores HCV-specific T cell responses and improves the control of HCV replication. Methods T cell responses were evaluated longitudinally in 80 HIV/HCV coinfected individuals by ex vivo interferon-γ-ELISpot responses to HCV core peptides, that predominantly stimulate CD4+ T cells. HCV RNA levels were assessed by real-time PCR in 114 individuals. Results The proportion of individuals with detectable T cell responses to HCV core peptides was 19% before starting cART, 24% in the first year on cART and increased significantly to 45% and 49% after 33 and 70 months on cART (p=0.001). HCV-specific immune responses increased in individuals with chronic (+31%) and spontaneously cleared HCV infection (+30%). Median HCV RNA levels before starting cART were 6.5 log10 IU/ml. During long-term cART, median HCV-RNA levels slightly decreased compared to pre-cART levels (−0.3 log10 IU/ml, p=0.02). Conclusions Successful cART is associated with increasing cellular immune responses to HCV core peptides and with a slight long-term decrease in HCV RNA levels. These findings are in line with the favourable clinical effects of cART on the natural history of hepatitis C and with the current recommendation to start cART earlier in HCV/HIV coinfected individuals.

Immune adaptations that maintain homeostasis with the intestinal microbiota

Humans harbour nearly 100 trillion intestinal bacteria that are essential for health. Millions of years of co-evolution have moulded this human-microorganism interaction into a symbiotic relationship in which gut bacteria make essential contributions to human nutrient metabolism and in return occupy a nutrient-rich environment. Although intestinal microorganisms carry out essential functions for their hosts, they pose a constant threat of invasion owing to their sheer numbers and the large intestinal surface area. In this Review, we discuss the unique adaptations of the intestinal immune system that maintain homeostatic interactions with a diverse resident microbiota.

Hypersensitivity and oral tolerance in the absence of a secretory immune system

Mucosal immunity protects the epithelial barrier by immune exclusion of foreign antigens and by anti-inflammatory tolerance mechanisms, but there is a continuing debate about the role of secretory immunoglobulins (SIgs), particularly SIgA, in the protection against allergy and other inflammatory diseases. Lack of secretory antibodies may cause immune dysfunction and affect mucosally induced (oral) tolerance against food antigens.

Drug antigenicity, immunogenicity, and costimulatory signaling: evidence for formation of a functional antigen through immune cell metabolism

Recognition of drugs by immune cells is usually explained by the hapten model, which states that endogenous metabolites bind irreversibly to protein to stimulate immune cells. Synthetic metabolites interact directly with protein-generating antigenic determinants for T cells; however, experimental evidence relating intracellular metabolism in immune cells and the generation of physiologically relevant Ags to functional immune responses is lacking. The aim of this study was to develop an integrated approach using animal and human experimental systems to characterize sulfamethoxazole (SMX) metabolism-derived antigenic protein adduct formation in immune cells and define the relationship among adduct formation, cell death, costimulatory signaling, and stimulation of a T cell response. Formation of SMX-derived adducts in APCs was dose and time dependent, detectable at nontoxic concentrations, and dependent on drug-metabolizing enzyme activity. Adduct formation above a threshold induced necrotic cell death, dendritic cell costimulatory molecule expression, and cytokine secretion. APCs cultured with SMX for 16 h, the time needed for drug metabolism, stimulated T cells from sensitized mice and lymphocytes and T cell clones from allergic patients. Enzyme inhibition decreased SMX-derived protein adduct formation and the T cell response. Dendritic cells cultured with SMX and adoptively transferred to recipient mice initiated an immune response; however, T cells were stimulated with adducts derived from SMX metabolism in APCs, not the parent drug. This study shows that APCs metabolize SMX; subsequent protein binding generates a functional T cell Ag. Adduct formation above a threshold stimulates cell death, which provides a maturation signal for dendritic cells.