Immunopathology as a result of highly active antiretroviral therapy in HIV-1-infected patients

Enhanced IFN-γ, but not IL-2, response to Mycobacterium tuberculosis antigens in HIV/latent TB co-infected patients on long-term HAART

BACKGROUND

HIV-infected individuals with latent TB infection are at increased risk of developing active TB. HAART greatly reduces the incidence rate of TB in HIV-infected patients and reconstitutes Mycobacterium tuberculosis (M. tuberculosis)-specific immune response in the first 12 months of therapy. The durability of the anti-mycobacterial immune restoration after a year of HAART however remains less investigated.

METHOD

A cross-sectional study was conducted to evaluate M. tuberculosis-specific functional immune responses in HIV/latent TB co-infected patients who were on HAART for at least 1.5 up to 9 years as compared to HAART-naïve patients. Three-hundred sixteen HIV-infected patients without active TB were screened by tuberculin skin testing for M. tuberculosis infection and peripheral blood mononuclear cells (PBMCs) were isolated from 61 HIV/latent TB co-infected patients (30 HAART-naïve and 31 HAART-treated). IFN-γ and IL-2 ELISPOT as well as CFSE cell proliferation assays were performed after stimulation with M. tuberculosis antigens PPD and ESAT-6.

RESULT

The median frequency of PPD and ESAT-6 specific IFN-γ secreting cells was significantly higher in the HAART-treated patients as compared to HAART-naïve patients, p = 0.0021 and p = 0.0081 respectively. However, there was no significant difference in the median frequency of IL-2 secreting cells responding to PPD (p = 0.5981) and ESAT-6 (p = 0.3943) antigens between HAART-naïve and-treated groups. Both IFN-γ and IL-2 responses were independent of CD4+ T cell count regardless of the HAART status. Notably, the frequency of PPD and ESAT-6 specific IL-2 secreting cells was positively associated with CD4+ T cell proliferation while inversely correlated with duration of HAART, raising the possibility that M. tuberculosis-specific IL-2 response that promote the antigen-specific CD4+ T cell proliferation diminish with time on antiretroviral therapy in HIV/latent TB co-infected patients.

CONCLUSION

This study shows an increased M. tuberculosis-specific IFN-γ, but not IL-2, response in HIV/latent TB co-infected patients with long-term HAART, consistent with only partial immune restoration. Future studies should, therefore, be done to prospectively define the rate and extent to which functional immune responses to M. tuberculosis are restored after long-term HAART.

Increase in HSV shedding at initiation of antiretroviral therapy and decrease in shedding over time on antiretroviral therapy in HIV and HSV-2 infected persons

OBJECTIVES

HIV-infected persons with chronic herpesvirus infections may experience paradoxical worsening after initiation of antiretroviral therapy (ART), but the impact of longer term ART is unclear. We evaluated the relationships between genital herpes simplex virus (HSV) shedding and ART initiation and time on therapy in HIV and HSV-2-infected persons.

DESIGN

Prospective observational study.

METHODS

Rates of HSV shedding in 45 HIV and HSV-2-infected persons on or off ART were prospectively followed over up to three, noncontiguous, 60-day periods, during which participants performed daily genital swabs for HSV detection by real-time HSV DNA PCR and reported symptoms. Initiation or discontinuation of ART was at the discretion of participants' healthcare providers.

RESULTS

In all, 6425 daily genital swabs were obtained from 45 persons (38 men and seven women) during 105 swabbing sessions. During the three sessions, 67, 74, and 92% of persons were on ART. HSV was detected on 26.5% of days in men and 22.3% of days in women. The overall rates of genital HSV shedding were 19.4% of days in persons not on ART, 30.2% in persons within 90 days of ART initiation, and 23.3% in persons on ART for longer than 90 days. After initiation of ART, HSV shedding decreased by 2% per month, or 23% per year (RR 0.98/month on ART; P = 0.0003 in adjusted analysis). This finding was consistent after including consideration of HIV viral load and CD4 cell count.

CONCLUSIONS

HSV shedding increased significantly shortly after ART initiation, but decreased with time on prolonged ART.

Thalidomide for steroid-dependent chronic disseminated candidiasis after stem cell transplantation: A case report

Chronic disseminated candidiasis (CDC) is a rare and difficult-to-treat invasive fungal disease occurring mainly after prolonged and profound neutropenia. We describe the case of a 59-year-old man successfully treated with thalidomide for CDC recurrences after an autologous transplantation. We add evidence of the effectiveness of immunomodulatory drugs to manage inflammatory reconstitution immune syndrome-related refractory CDC.

Foreign Body Granuloma: A New Manifestation of Immune Restoration Syndrome

Background:

People with human immunodeficiency virus may experience an immune restoration syndrome during the lymphocyte recovery period following effective highly active antiretroviral therapy. In this syndrome, antigens that previously were ignored by the immune system now induce an exaggerated response with obvious clinical effects. Most cases have been associated with infectious agents such as cytomegalovirus or mycobacterium avium intracellulare. However, the sudden onset of sarcoidal granulomatous reactions have also been described in this setting.

Objective:

We report a 66-year-old HIV-positive man who presented with exacerbation of multiple foreign body granulomas decades after the original injuries. The presentation coincided with a significant rise in CD4 count after beginning highly active antiretroviral therapy.

Conclusion:

We propose that this case demonstrates another manifestation of the immune restoration syndrome and postulate that an uncontrolled Th1 response is the causative mechanism.

Encephalitis with infiltration by CD8+ lymphocytes in HIV patients receiving combination antiretroviral treatment

We report the neuropathological findings in 10 HIV-infected patients treated by combination antiretroviral therapy who developed subacute encephalopathy of rapidly progressive onset. Brain biopsy showed encephalitic lesions variably associated with myelin loss and slight axonal damage. There was inconstant, weak expression of HIV protein p24; tests for other pathogens were negative. The most striking feature was diffuse, perivascular and intraparenchymal infiltration by CD8+ T-lymphocytes. Six patients improved after the treatment. Four had an unfavorable outcome and died within a year. Post-mortem in one case confirmed HIV leukoencephalitis with p24-positive multinucleated giant cells, associated with acute demyelinating encephalomyelitis (ADEM) in the cerebellum. There was diffuse infiltration by CD8+ lymphocytes; CD4+ cells were virtually absent. These cases may represent a specific clinicopathological entity, of which a few comparable cases have been already described. They can be included in the wide framework of immune reconstitution disease. Such syndromes have been described with opportunistic infections, but only seldom with HIV infection of the central nervous system (CNS). Our findings support the hypothesis that CD8+ cytotoxic lymphocytes can be harmful in immune reconstitution disease, particularly in the absence of CD4+ lymphocytes. CD8 cytotoxicity produces an acutization of a smoldering infection and/or an immunopathological reaction similar to ADEM.

Late onset CNS immune reconstitution inflammatory syndrome in an immunocompetent patient

Immune reconstitution inflammatory syndrome (IRIS) refers to the presence of paradoxical clinical deterioration attributable to immune system recovery during highly active antiretroviral therapy (HAART). We present an immunocompetent patient with multifocal leukoencephalopathy on HAART, with central nervous system (CNS) IRIS pathology of unknown infectious etiology. CNS IRIS pathology should be suspected in patients on longstanding HAART without immune reconstitution, presenting with unexplained leukoencephalopathy.

Depression of local cell-mediated immunity and histological characteristics of disseminated AIDS-related Mycobacterium avium infection after the initiation of antiretroviral therapy

OBJECTIVE

The aim of the present study was to examine the immunohistological characteristics of disseminated Mycobacterium avium infection after the initiation of antiretroviral therapy (ART) for acquired immunodeficiency syndrome (AIDS).

METHODS

We histologically investigated five autopsied AIDS patients with systemic M. avium infection.

RESULTS

The inflammatory cell composition in the affected tissues was assessed using immunohistochemistry. The celiac lymph nodes and intestinal canal were the most commonly involved organs in the AIDS cases. The most common histological feature was unstructured aggregation of histiocytes. Immunohistochemistry revealed depression of CD4(+), CD8(+) and CD57(+) cells in the gut lamina propria and mesenteric lymph nodes.

CONCLUSION

These findings suggest that local cell-mediated immunity is depressed in affected tissues and that the primary histological feature is poor organization of granulomas in mycobacterial lesions, despite the administration of adequate ART.

Elevated interleukin 8 and T-helper 1 and T-helper 17 cytokine levels prior to antiretroviral therapy in participants who developed immune reconstitution inflammatory syndrome during ACTG A5164

BACKGROUND

Immune reconstitution inflammatory syndrome (IRIS) reflects an aberrant immune response that can develop in human immunodeficiency virus-infected patients initiating antiretroviral therapy (ART). Its pathogenesis remains unclear.

METHODS

We performed a nested case-control study using specimens from ACTG A5164. We compared plasma biomarkers and T-cell subsets in 19 IRIS and 39 control participants at study entry, ART initiation, and IRIS and used conditional logistic regression to develop IRIS predictive models. We evaluated the effect of corticosteroids on biomarker levels.

RESULTS

Eleven and 8 participants developed paradoxical and unmasking IRIS, respectively, none while still receiving corticosteroids. Compared to controls, cases displayed elevations at study entry in interleukin (IL) 8, T-helper (Th) 1 (IL-2, interferon [IFN]-γ, tumor necrosis factor [TNF]) and Th17 (IL-17) cytokine levels that persisted through ART initiation and IRIS. In logistic regression, baseline higher IFN-γ and TNF were strong predictors of IRIS. Participants who received corticosteroids and later developed IRIS had marked increases in IL-6, IL-8, and IFN-γ at the time of IRIS. T-cell activation markers did not differ in cases and controls prior to ART but were increased in cases at the time of IRIS.

CONCLUSIONS

Increased IL-8, Th1, and Th17 cytokine levels in IRIS patients precede ART initiation and could help identify patient populations at higher risk for IRIS.

Antiretroviral treatment as prevention: impact of the 'test and treat' strategy on the tuberculosis epidemic

Antiretroviral therapy (ART) has been remarkably effective in ameliorating Human Immunodeficiency Virus (HIV)-associated morbidity and mortality. The rapid decline in viral load during ART also presents an opportunity to develop a “treatment as prevention” strategy in order to reduce HIV transmission at a population level. Modelling exercises have demonstrated that for this strategy to be effective, early initiation of ART with high coverage of the HIV-infected population will be required. The HIV epidemic has fueled a resurgence of tuberculosis (TB) particularly in sub-Saharan Africa and widespread early initiation of ART could also impact this epidemic via several mechanisms. The proportion of patients with low CD4 cell counts who are at high risk of TB disease from progression of both latent and new TB infection would be greatly reduced. Entry into a life-long ART program provides an ongoing opportunity for intensified TB case finding among the HIV-infected population. Regular screening for HIV infection also presents an opportunity for intensified TB case finding in the general population. The combined effect of reduced progression of infection to disease and intensified case finding could reduce the overall prevalence of infectious TB, thereby further decreasing TB transmission. In addition, decreasing prevalence of HIV infection would reduce the TB-susceptible pool within the population. The ‘test and treat’ strategy therefore has potential to reduce the TB risk at both an individual and a population level. In this paper we explore the expected “TB dividend” of wider access to ART and also explore the potential of the “test and treat” strategy to impact on TB transmission, particularly in the heavily burdened setting of sub-Saharan Africa.

Antiretroviral therapy and the control of HIV-associated tuberculosis. Will ART do it?

The human immunodeficiency virus (HIV) associated tuberculosis (TB) epidemic remains an enormous challenge to TB control in countries with a high prevalence of HIV. In their 1999 article entitled 'Will DOTS do it?', De Cock and Chaisson questioned whether the World Health Organization's DOTS Strategy could control this epidemic. Data over the past 10 years have clearly shown that DOTS is insufficient as a single TB control intervention in such settings because it does not address the fundamental epidemiological interactions between TB and HIV. Immunodeficiency is a principal driver of this epidemic, and the solution must therefore include immune recovery using antiretroviral therapy (ART). Thus, in the era of global ART scale-up, we now ask the question, 'Will ART do it?' ART reduces the risk of TB by 67% (95%CI 61-73), halves TB recurrence rates, reduces mortality risk by 64-95% in cohorts and prolongs survival in patients with HIV-associated drug-resistant TB. However, the cumulative lifetime risk of TB in HIV-infected individuals is a function of time spent at various CD4-defined levels of risk, both before and during ART. Current initiation of ART at low CD4 cell counts (by which time much HIV-associated TB has already occurred) and low effective coverage greatly undermine the potential impact of ART at a population level. Thus, while ART has proven a critical intervention for case management of HIV-associated TB, much of its preventive potential for TB control is currently being squandered. Much earlier ART initiation with high coverage is required if ART is to substantially influence the incidence of TB.

Pulmonary manifestations of the immune reconstitution inflammatory syndrome

PURPOSE OF REVIEW

Immune reconstitution inflammatory syndrome (IRIS) is a common occurrence in HIV patients starting antiretroviral therapy (ART), and pulmonary involvement is an important feature of tuberculosis-IRIS and pneumocystis-IRIS. Pulmonologists need an awareness of the timing, presentation and treatment of pulmonary IRIS.

RECENT FINDINGS

Case definitions for tuberculosis-IRIS and cryptococcal-IRIS have been published by the International Network for the Study of HIV-associated IRIS (INSHI). A number of studies have addressed validation of clinical case definitions and the optimal time to commence ART after diagnosis of an opportunistic infection in HIV patients. The pathogenesis of IRIS is being assessed at a molecular level, increasing our understanding of mechanisms and possible targets for future preventive and therapeutic strategies.

SUMMARY

Tuberculosis-IRIS, nontuberculosis mycobacterial-IRIS and pneumocystis-IRIS occur within days to weeks of starting ART, causing substantial morbidity, but low mortality. Cryptococcal-IRIS usually occurs later in the course of ART, and may be associated with appreciable mortality. Early recognition of unmasking and paradoxical IRIS affecting the lung allows timely initiation of antimicrobial and/or immunomodulatory therapies.

Immunopathological characteristics of immune reconstitution inflammatory syndrome caused by Mycobacterium parascrofulaceum infection in a patient with AIDS

Immune reconstitution inflammatory syndrome (IRIS) caused by mycobacterium in patients with AIDS is often experienced in clinical practice. There is, however, a paucity of data documenting the histopathological findings and the pathogenesis. We determined the immunopathological characteristics of IRIS associated with Mycobacterium parascrofulaceum infection in an AIDS patient. A patient presented with pulmonary lymphadenitis and involvement of the pulmonary lingular segment. Portions of the involved lymph nodes and lung were excised, and the immunological properties were analyzed by immunohistochemical assays. The histological characteristics of lymph nodes showed a caseous necrosis. Histopathologically, the pulmonary lesion was composed of exudative and proliferative lesions. CD4(+), CD8(+), CD57(+), and CD25(+)/FoxP3(+) cells were observed in both types of lesions. Clusters of CD20(+) cells and GATA3(+) cells were predominantly observed in exudative lesions, while T-bet(+) cells were dominant in proliferative lesions. ROR-γ(+) cells were also observed in exudative lesions. These results indicate that the cellular immunity to mycobacteria was recovering in the lung tissue. In M. parascrofulaceum pulmonary infection, the exudative lesion had characteristics of Th2 and Th17-type immunities. In contrast, the proliferative lesion had characteristics of Th-1 type immunity. Our data provide the first evidence to reveal the status of the axis of distinctive immunity in the process of granuloma formation caused by a mycobacterium-related infection.

Biomarkers in immune reconstitution inflammatory syndrome: signals from pathogenesis

PURPOSE OF REVIEW

Immune reconstitution inflammatory syndrome (IRIS) is the paradoxical worsening or unmasking of an infection or neoplasm in HIV-1-infected patients shortly after antiretroviral therapy (ART) initiation. New insights into the pathogenesis of IRIS may help identify biomarkers that could be useful in predicting or diagnosing IRIS.

RECENT FINDINGS

Studies of immunopathogenesis have shown a signification activation of both innate and adaptive immune responses with elevation of plasma or serum chemokines and cytokines. Markers of inflammation such as C-reactive protein, interferon-inducible protein 10 or interferon γ may be helpful as predictors of IRIS events. In addition, tuberculosis (TB)-associated IRIS is associated with a prominent Th1 response that can be heightened even prior to ART initiation in cases of unmasking TB, and may assist in early diagnosis. Large prospective studies are needed to elucidate the predictive and diagnostic value of IRIS biomarkers and advance them to the clinic.

SUMMARY

Reversal of immunosuppression by ART leads to exaggerated pathogen-specific immune responses (known as IRIS) that appear to be primed prior to therapy. Inflammatory markers, chemokines and cytokines that signify innate and adaptive immune activation are biomarkers that could prove of clinical value after appropriate validation.

Immune restoration disease and changes in CD4+ T-cell count in HIV- infected patients during highly active antiretroviral therapy at Zewditu memorial hospital, Addis Ababa, Ethiopia

Background

Highly active antiretroviral therapy (HAART) improves the immune function and decreases morbidity, mortality and opportunistic infections (OIs) in HIV-infected patients. However, since the use of HAART, immune restoration disease (IRD) has been described in association with many OIs. Our objective was to determine the proportion of IRD, changes in CD4+ T-cell count and possible risk factors of IRD in HIV-infected patients.

Methods

A retrospective study of all HIV- infected patients starting HAART between September 1, 2005 and August 31, 2006 at Zewditu memorial hospital HIV clinic, Addis Ababa, Ethiopia was conducted. All laboratory and clinical data were extracted from computerized clinic records and patient charts.

Results

A total of 1166 HIV- infected patients with mean ± SD age of 36 ± 9.3 years were on HAART. IRD was identified in 170 (14.6%) patients. OIs diagnosed in the IRD patients were tuberculosis (66.5%, 113/170), toxoplasmosis (12.9%, 22/170), herpes zoster rash (12.9%, 22/170), Pneumocystis jirovecii pneumonia (4.1%, 7/170), and cryptococcosis (3.5%, 6/170). Of the 170 patients with IRD, 124 (72.9%) patients developed IRD within the first 3 months of HAART initiation. Low baseline CD4+ T-cell count (odds ratio [OR], 3.16, 95% confidence interval [CI], 2.19-4.58) and baseline extra pulmonary tuberculosis (OR, 7.7, 95% CI, 3.36-17.65) were associated with development of IRD. Twenty nine (17.1%) of the IRD patients needed to use systemic anti-inflammatory treatment where as 19(11.2%) patients required hospitalization associated to the IRD occurrence. There was a total of 8 (4.7%) deaths attributable to IRD.

Conclusions

The proportion and risk factors of IRD and the pattern of OIs mirrored reports from other countries. Close monitoring of patients during the first three months of HAART initiation is important to minimize clinical deterioration related to IRD.

Risk factor analyses for immune reconstitution inflammatory syndrome in a randomized study of early vs. deferred ART during an opportunistic infection

Background

Immune reconstitution inflammatory syndrome (IRIS) is reported widely in patients initiating antiretroviral therapy (ART). However, few studies are prospective, and no study has evaluated the impact of the timing of ART when allocated randomly during an acute opportunistic infection (OI).

Methodology/Principal Findings

A5164 randomized 282 subjects with AIDS-related OIs (tuberculosis excluded), to early or deferred ART. IRIS was identified prospectively using pre-defined criteria. We evaluated associations between IRIS and baseline variables in subjects with follow-up on ART using Wilcoxon and Fisher's exact tests, logistic regression, and Cox models with time-varying covariates. Twenty of 262 (7.6%) subjects developed IRIS after a median of 33 days on ART. Subjects with fungal infections (other than pneumocystis) developed IRIS somewhat more frequently (OR = 2.7; 95% CI: 1.02, 7.2; p-value = 0.06 (using Fisher's exact test)). In Cox models, lower baseline and higher on-treatment CD4+ T-cell counts and percentage were associated with IRIS. Additionally, higher baseline and lower on-treatment HIV RNA levels were associated with IRIS. Corticosteroids during OI management and the timing of ART were not associated with the development of IRIS.

Implications

In patients with advanced immunosuppression and non-tuberculous OIs, the presence of a fungal infection, lower CD4+ T-cell counts and higher HIV RNA levels at baseline, and higher CD4+ T-cell counts and lower HIV RNA levels on treatment are associated with IRIS. Early initiation of ART does not increase the incidence of IRIS, and concern about IRIS should not prompt deferral of ART.

Trial Registration

ClinicalTrials.gov NCT00055120

Pulmonary complications of immune reconstitution inflammatory syndromes in HIV-infected patients

Immune reconstitution inflammatory syndrome (IRIS) describes a paradoxical worsening of clinical status related to recovery of the immune system, as can occur after the initiation of highly active antiretroviral therapy (HAART) in HIV-infected patients. Most commonly, IRIS results from opportunistic infections that can unmask or develop paradoxical worsening following HAART. Cancers, autoimmune conditions and sarcoidosis have also been associated with IRIS. Pulmonary complications may be frequently encountered. This article reviews the types and clinical presentation of IRIS, with a focus on the pulmonary manifestations. Management and outcome of IRIS are considered.

[Acute renal failure and hypercalcemia in an AIDS patient on tenofovir and low-dose vitamin D therapy with immune reconstitution inflammatory syndrome]

BACKGROUND

Tenofovir-containing antiviral therapy might result in acute renal failure and is able to induce tubular dysfunction with hypocalcemia. On the other hand, hypercalcemia induced by intoxication with colecalciferol has been described to induce renal failure in HIV-positive individuals as well. Here, the authors describe the unusual case of reversible renal failure due to hypercalcemia in a patient with low-dose colecalciferol substitution treated with tenofovir.

CASE REPORT

A 31-year-old HIV-positive female, CDC stage C3, was admitted to the authors' hospital with progressive renal failure and hypercalcemia. Antiretroviral therapy consisted of tenofovir and emtricitabine in combination with efavirenz. Additionally, she was on low-dose vitamin D(3) substitution (25 microg/d) and calcium supplementation (500 mg/d) due to systemic steroid treatment.

CONCLUSION

Additionally to regular control of renal function, serologic level of calcium should be supervised in patients concomitantly treated with tenofovir and colecalciferol.

Immune reconstitution inflammatory syndrome in HIV-infected patients receiving antiretroviral therapy : pathogenesis, clinical manifestations and management

The use of antiretroviral therapy (ART) to treat HIV infection, by restoring CD4+ cell count and immune function, is associated with significant reductions in morbidity and mortality. Soon after ART initiation, there is a rapid phase of restoration of pathogen-specific immunity. In certain patients, this results in inflammatory responses that may result in clinical deterioration known as 'the immune reconstitution inflammatory syndrome' (IRIS). IRIS may be targeted at viable infective antigens, dead or dying infective antigens, host antigens, tumour antigens and other antigens, giving rise to a heterogeneous range of clinical manifestations. The commonest forms of IRIS are associated with mycobacterial infections, fungi and herpes viruses. In most patients, ART should be continued and treatment for the associated condition optimized, and there is anecdotal evidence for the use of corticosteroids in patients who are severely affected. In this review, we discuss research relating to pathogenesis, the range of clinical manifestations, treatment options and prevention issues.

Insights into pathogenic events of HIV-associated Kaposi sarcoma and immune reconstitution syndrome related Kaposi sarcoma

A decrease in the incidence of human immune deficiency virus-associated Kaposi sarcoma (HIV-KS) and regression of some established HIV-KS lesions is evident after the introduction of highly active anti-retroviral treatment (HAART), and is attributed to generalized immune restoration, to the reconstitution of human herpesvirus (HHV)-8 specific cellular immune responses, and to the decrease in HIV Tat protein and HHV-8 loads following HAART. However, a small subset of HIV-seropositive subjects with a low CD4+ T cell count at the time of introduction of HAART, may develop HIV-KS as immune reconstitution inflammatory syndrome (IRIS) within 8 weeks thereafter.

Immune reconstitution and "unmasking" of tuberculosis during antiretroviral therapy

Tuberculosis (TB) is the most common opportunistic disease in HIV-infected patients during the initial months of antiretroviral therapy (ART) and presents a great challenge to ART programs in resource-limited settings. The mechanisms underlying development of TB in this period are complex. Some cases may represent progression of undiagnosed subclinical disease present before starting ART, emphasizing the importance of careful screening strategies for TB. It has been suggested that progression in such cases is due to immune reconstitution disease-a phenomenon in which dysregulated restoration of pathogen-specific immune responses triggers the presentation of subclinical disease. However, whereas some cases have exaggerated or overtly inflammatory manifestations consistent with existing case definitions for IRD, many others do not. Moreover, since ART-induced immune recovery is a time-dependent process, active TB may develop as a consequence of persisting immunodeficiency. All these mechanisms are likely to be important, representing a spectrum of complex interactions between mycobacterial burden and changing host immune response. We propose that the potential range of effects of ART includes (1) shortening of the time for subclinical TB to become symptomatic (a phenomenon often referred to as "unmasking"), (2) increased rapidity of initial onset of TB symptoms, and (3) heightened intensity of clinical manifestations. We suggest that the term "ART-associated TB" be used to refer collectively to all cases of TB presenting during ART and that "immune reconstitution disease" be used to refer to the subset of ART-associated TB cases in which the effect on disease severity results in exaggerated and overtly inflammatory disease.

Neuropathologic contributions to understanding AIDS and the central nervous system

This historical review describes the evolution of the pathogenetic concepts associated with infection by the Human Immunodeficiency Virus (HIV), with emphasis on the pathology of the nervous system. Although the first descriptions of damage to the nervous system in the acquired immunodeficiency syndrome (AIDS) only appeared in 1982, the dramatic diffusion of the epidemic worldwide and the invariably rapidly fatal outcome of the disease, before the introduction of efficient treatment, generated from the beginning an enormous amount of research with rethinking on a number of pathogenetic concepts. Less than 25 years after the first autopsy series of AIDS patients were published and the virus responsible for AIDS was identified, satisfactory definition and classification of a number of neuropathological complications of HIV infection have been established, leading to accurate clinical radiological and biological diagnosis of the main neurological complications of the disease, which remain a major cause of disability and death in AIDS patients. Clinical and experimental studies have provided essential insight into the pathogenesis of CNS lesions and natural history of the disease. The relatively recent introduction of highly active antiretroviral therapy (HAART) in 1995-1996 has dramatically improved the course and prognosis of HIV disease. However, there remain a number of unsolved pathogenetic issues, the most puzzling of which remains the precise mechanism of neuronal damage underlying the specific HIV-related cognitive disorders (HIV dementia). In addition, although HAART has changed the course of neurological complications of HIV infection, new issues have emerged such as the lack of improvement or even paradoxical deterioration of the neurological status in treated patients. Interpretation of these latter data remains largely speculative partly because of the small number of neuropathological studies related to the beneficial consequence of this treatment.

Disorders of immune reconstitution in patients with HIV infection responding to antiretroviral therapy

Patients with HIV infection who were very immunodeficient before achieving a virologic response to antiretroviral therapy (ART) may experience various disorders of immune reconstitution. Immune restoration disease occurs in approximately 10% to 50% of patients and results from the restoration of a pathogen-specific immune response that causes immunopathology and presents as tissue inflammation or cellular proliferative disease. Opportunistic infections occur in no more than 5% of patients, but approximately one half of these patients have higher than expected CD4 T-cell counts and appear to have residual immune dysfunction. Autoimmune disease may arise because the reconstituted immune system confers an increased susceptibility to immune dysregulation but there may be different mechanisms because Graves' disease presents after a median time of about 2 years of ART whereas systemic lupus erythematosus presents earlier. Persistent CD4 T-cell deficiency (< 500/microL) affects up to 60% of patients and appears to reflect depletion of the naïve T-cell pool that results from low production and/or increased turnover of cells.

Immune reconstitution disease associated with parasitic infections following antiretroviral treatment

HIV-associated immune reconstitution disease (IRD) is the clinical presentation or deterioration of opportunistic infections that results from enhancement of pathogen-specific immune responses among patients responding to antiretroviral treatment (ART). The vast majority of reported cases of IRD have been associated with mycobacterial, chronic viral and invasive fungal infections; such cases result from dysregulated augmentation of cell-mediated type 1 cytokine-secreting host immune responses. However, the spectrum of infections now recognized as associated with IRD is expanding and includes a number of parasitic infections, which may be mediated by different immunopathological mechanisms. These include leishmaniasis (visceral, cutaneous, mucosal and post kala azar dermal leishmaniasis), schistosomiasis and strongyloidiasis. Since the major burden of HIV lies in resource-limited countries where access to ART is now rapidly expanding, increased awareness and knowledge of these phenomena is important. Here we review the clinical spectrum and pathogenesis of IRD associated with parasitic infections.

The radiology of IRIS (immune reconstitution inflammatory syndrome) in patients with mycobacterial tuberculosis and HIV co-infection: appearances in 11 patients

AIM

To determine the radiological manifestations of IRIS (immune reconstitution inflammatory syndrome) in patients with HIV and mycobacterium tuberculosis co-infection, in the context of their demographic and clinical data.

MATERIALS AND METHODS

The radiological imaging, demographic and clinical data of 11 patients diagnosed with IRIS associated with HIV and mycobacterial tuberculosis co-infection were studied retrospectively. Where available, follow-up imaging studies were also reviewed.

RESULTS

The most common radiological feature of IRIS was lymph node enlargement (73%), with central low attenuation centres, in keeping with necrosis, present in most of these cases (88%). Most commonly affected were intra-abdominal nodes (70%), followed by axillary (40%) and mediastinal lymph nodes (36%). Within the lung parenchyma, diffuse, bilateral pulmonary nodules were seen in 55% of cases. Unilateral small volume pleural effusions were seen in two cases with associated parenchymal changes seen in only one. Small volume ascites was seen in two cases. Thirty-six percent of cases presented with new or worsening abscesses despite treatment. In this context, image-guided radiological drainage proved a useful adjunct to the conventional medical therapy for IRIS. The most common clinical signs of IRIS included fever (64%), abdominal pain (36%) and cough (27%).

CONCLUSION

We have described the radiological features that are characteristic in IRIS and the importance of putting these into context with the clinical and pathological findings as part of a multidisciplinary approach in making the diagnosis. The role of the radiologist is central in diagnosis, monitoring of disease progression and management of complications in patients with IRIS.

Evidence base for using corticosteroids to treat HIV-associated immune reconstitution syndrome

Most of the evidence supporting the use of corticosteroids (steroids) for immune reconstitution syndrome (IRS) comes from case reports or retrospective series and is of low quality. However, when steroids are used, they have usually been associated with clinical improvement or resolution of IRS. Except in the case of hepatitis B- or C-associated IRS, there have been no reports of worsening of the IRS or adverse outcome due to steroid use. After ruling out other conditions which can mimic IRS, clinicians should strongly consider steroids when managing IRS associated with mycobacterial or fungal pathogens when there is severe disease, or when other measures have failed.

Immune reconstitution inflammatory syndrome in HIV

PURPOSE OF REVIEW

The purpose of this review is to describe the epidemiology, clinical features, putative immune mechanisms and management of immune reconstitution inflammatory syndrome (IRIS) using data published in the last 2 years.

RECENT FINDINGS

Ever more conditions are reported as IRIS events. These most frequently occur with mycobacterial (tuberculosis or Mycobacterium avium complex infection) or cryptococcal disease (each in approximately 30% of cases). Definitions have been proposed for its clinical diagnosis. These suffer from a lack of prospective studies to support their predictive value. The immunopathogenesis of IRIS appears to be related to the interaction between HAART-induced changes in host immune response and the presence of (usually microbial) antigen. Increasing evidence exists that this might be an anatomically compartmentalized phenomenon, such that immune responses may be localized to specific tissue sites such as the brain. This has implications for the use of simple blood tests, such as CD4 count or change in viral load, when assessing risk of IRIS. Treatment options include immune modulation, though supportive care is typically all that is required, unless symptoms are prolonged, significant or life-threatening.

SUMMARY

IRIS is common and will become more so as HAART is rolled out worldwide. Clear clinical definitions are required to avoid its over-diagnosis due to misclassification of other conditions.

Incidence and Risk Factors for Immune Reconstitution Inflammatory Syndrome in an Ethnically Diverse HIV Type 1-Infected Cohort

BACKGROUND

It is estimated that 10%-25% of patients who start highly active antiretroviral therapy (HAART) experience immune reconstitution inflammatory syndrome (IRIS). Our objective was to determine the incidence, clinical spectrum, and predictors of IRIS in an ethnically diverse cohort of patients initiating HAART.

METHODS

A retrospective study of all patients starting HAART between 1 January 2000 and 31 August 2002 at a human immunodeficiency virus (HIV) clinic in London was performed. All laboratory measurements and data on antiretroviral therapies were obtained from the clinic database. Medical records were reviewed to identify clinical events consistent with IRIS during the 6 months after HAART was initiated.

RESULTS

A total of 199 patients were included, of whom 50.8% were male, 59.3% were black African, 29.1% were white, and 10.5% were black Caribbean. The median baseline CD4 cell count and HIV RNA load were 174x10(6) cells/L (interquartile range [IQR], 82-285x10(6) cells/L) and 37,830 copies/mL (IQR, 4809-149,653 copies/mL), respectively. Forty-four patients (22.7%) experienced an IRIS event at a median of 12 weeks after HAART initiation (IQR, 4-24 weeks after initiation); 22 events (50%) involved genital herpes, 10 (23%) involved genital warts, 4 (9.0%) involved molluscum contagiosum, and 4 (9.0%) involved varicella zoster virus infection. Five patients had mycobacterial infections, 4 had hepatitis B, 1 had Pneumocystis jirovecci infection, and 1 had Kaposi sarcoma. The strongest independent predictors of IRIS were younger age at initiation of HAART (P=.003), baseline CD4 cell percentage of <10% (odds ratio [OR], 2.97; IQR, 1.17-7.55) compared with >15%, and ratio of CD4 cell percentage to CD8 cell percentage of <0.15 (OR, 3.45; 95% confidence interval, 1.27-9.1) compared with >0.3.

CONCLUSIONS

Approximately one-quarter of patients who start HAART experience an IRIS event. The majority are dermatological, in particular genital herpes and warts. Patients with advanced immunodeficiency at HAART initiation are at greatest risk of developing IRIS and should be appropriately screened and monitored.

Explosion of tuberculin-specific Th1-responses induces immune restoration syndrome in tuberculosis and HIV co-infected patients

OBJECTIVES

To test the hypothesis that an acute exacerbation of mycobacteria-specific Th1 response after HIV infection control by HAART causes immune restoration syndrome (IRS) in HIV-tuberculosis (TB) coinfected patients.

DESIGN

Prospective, multicenter study of 19 consecutive untreated HIV-TB coinfected patients included when initiating antimycobacterial therapy and sequentially evaluated during HAART and at time of IRS. IRS was defined according to classical clinical diagnostic criteria. Patients were declared IRS- if no IRS occurred within 3 months after HAART initiation.

METHODS

Mycobacteria-specific [purified protein derivative (PPD), ESAT-6, 85B] Th1 cells producing interferon (IFN)-gamma quantified by ELISpot, in vitro production of 25 cytokines/chemokines in antigen-stimulated peripheral blood mononuclear cell (PBMC) supernatants quantified by chemiluminescence.

RESULTS

Seven patients (37%) experienced IRS (IRS+). Mycobacteria-specific (PPD) Th1 IFN-gamma-producing cells increased sharply during IRS (median, 2970 spot forming cells/10 PBMC), but not the cytomegalovirus-specific responses tested as control. Only three IRS+ patients had low ESAT-6- but no 85B-specific responses. IRS- patients did not develop acute PPD-specific responses except in one case. In addition, at time of IRS a peak of PPD-specific Th1 cytokines/chemokines [interleukin (IL)-2, IL-12, IFN-gamma, IP10 and monokine-induced by IFN-gamma] without Th2 cytokines, and a peak of non-specific inflammatory cytokines/chemokines (TNF-alpha, IL-6, IL-1beta, IL-10, RANTES and MCP-1) occurred. These findings were independent from CD4 cell count, viral loads or time of HAART initiation.

CONCLUSION

An acute exacerbation of Th1 responses against mycobacterial antigens appears to cause IRS in patients co-infected with HIV and TB. This key event provides new evidence valuable for the diagnosis and treatment of IRS.

Review editorial: prevention of tuberculosis in resource-poor countries with increasing access to highly active antiretroviral treatment

The administration of isoniazid (INH) has been proposed, evaluated and implemented to prevent tuberculosis (TB) disease among patients who are infected with the human immunodeficiency virus (HIV). This strategy has been developed in communities where TB is highly endemic and at a time when antiretroviral (ARV) treatment was not, or was rarely available. Although INH prevention programmes were somewhat pushed to the background due to the worldwide advocacy for ARV drugs, prevention of TB remains of paramount importance. The dual HIV-TB infection poses problems, not only for the individual and his/her clinician but also for the programme manager. We review various aspects of TB preventive treatment in countries with a high prevalence of HIV-TB co-infection and limited resources but with increasing access to ARV treatment.

Coreceptor usage of primary HIV type 1 isolates obtained from different lymph node subsets

Biological characteristics of virus quantitatively rescued from different cell types present in lymph nodes of HIV-1-infected individuals in various stages of their disease were determined, not including patients with AIDS defining illness. Viruses were obtained by cocultivation with donor monocyte-derived macrophages and T-lymphocytes and their biological phenotype compared to viruses obtained from the peripheral blood mononuclear cells of the same patient. The biological phenotype was determined on established cell lines (U937-2, CEM, and MT-2) and on the U87.CD4 coreceptor indicator cell lines and variable region 3 (V3) of the envelope was subjected to direct sequencing. All isolates obtained from lymph node subsets used CCR5 as coreceptor. Furthermore, these viruses were also sensitive to inhibition by beta-chemokines as analyzed for viruses of one patient. All 12 V3 regions showed a unique sequence indicating compartmentalization within each patient. The biological phenotype of CCR5-dependent (R5) HIV-1 isolates obtained from PBMC resembles the phenotype of viruses isolated from different lymph node cell subsets.

How effectively does HAART restore immune responses to Mycobacterium tuberculosis? Implications for tuberculosis control

Use of highly active antiretroviral treatment (HAART) has had a major impact on HIV-associated morbidity and mortality in industrialized countries. Access to HAART is now expanding in low-income countries where tuberculosis (TB) is the most important opportunistic disease. The incidence of TB has been fueled by the HIV epidemic and in many countries with high HIV prevalence current TB control measures are failing. HAART reduces the incidence of TB in treated cohorts by approximately 80% and therefore potentially has an important role in TB control in such countries. However, despite the huge beneficial effect of HAART, rates of TB among treated patients nevertheless remain persistently higher than among HIV-negative individuals. This observation raises the important question as to whether immune responses to Mycobacterium tuberculosis (MTB) are completely or only partially restored during HAART. Current data suggest that full restoration of circulating CD4 cell numbers occurs only among a minority of patients and that, even among these, phenotypic abnormalities and functional defects in lymphocyte subsets often persist. Suboptimal restoration of MTB-specific immune responses may greatly reduce the extent to which HAART is able to contribute to TB control at the community level because patients receiving HAART live much longer and yet would maintain a chronically heightened risk of TB.

Clinical characteristics of IRIS syndrome in patients with HIV and tuberculosis

BACKGROUND

Some patients with HIV/tuberculosis (TB) coinfection who are on anti-TB treatment and highly active antiretroviral therapy (HAART) will develop an exacerbation of symptoms, signs or radiological manifestations of TB that are not due to relapse or recurrence of their TB. The aetiology of these immune reconstitution inflammatory syndrome (IRIS) reactions is unknown but it is presumed that they occur, at least in part, as a consequence of HAART-related reconstitution of immunity.

METHODS

Patients who were diagnosed with their first episode of definitive or presumed TB between January 2001 and July 2003 were identified from the Chelsea and Westminster TB/HIV database. The patients were classified into those who developed IRIS and those who did not using a set definition of the syndrome. Demographic, clinical and laboratory data relating to both HIV and TB were compared between the two groups.

RESULTS

A total of 55 cases of TB were identified, of which 45 cases were confirmed on culture or gene probe and 10 were presumed cases. Fourteen cases (25.5%) developed IRIS with a median (range) duration of 2.53 (0.53-14.97) months. The median baseline CD4 [interquartile range (IQR)] for the IRIS group was significantly lower at 80 (33-117) cells/mm3 (P = 0.05) than the non-IRIS group at 139 (77-284) cells/mm3. A significantly greater proportion of patients in the IRIS group [11/14 (78.60%), P = 0.011] had baseline CD4 < 100cells/mm3 compared with the non-IRIS group [16/41 (39.0%)]. There was no significant difference between the two groups when comparing the log10 baseline viral load (VL). Eight (57.0%) patients in the IRIS group had disseminated TB at baseline compared with seven (17.0%) in the non-IRIS group (P = 0.006). In those who had a detectable VL at baseline, the median fold change (IQR) in CD4 from baseline to 3 months was significantly higher in the IRIS group patients, 1.5 (0.6-5.6), compared with 0.7 (-0.2 to 1.0) for those in the non-IRIS group (P = 0.046).

CONCLUSIONS

Patients who develop IRIS are more likely to present with disseminated TB, have a CD4 count < 100 cells/mm3 and have a prompt rise in CD4 count in the initial 3 months of HAART.

Immune reconstitution disease associated with mycobacterial infections in HIV-infected individuals receiving antiretrovirals

Immune reconstitution disease (IRD) in HIV-infected patients is an adverse consequence of the restoration of pathogen-specific immune responses during the initial months of highly active antiretroviral treatment (HAART). Previously subclinical infections are "unmasked" or pre-existing opportunistic infections clinically deteriorate as host immunopathological inflammatory responses are "switched on". IRD is most frequently associated with mycobacterial infections. Our literature search identified 166 published cases of IRD associated with mycobacterial infections. We review the underlying immunological mechanisms, difficulties surrounding case definition and diagnosis, the wide diversity of clinical manifestations, and treatment. The importance of screening patients for mycobacterial disease before starting HAART and the critical impact of the timing of commencement of HAART in patients receiving treatment for tuberculosis are highlighted. We also discuss the problem of IRD associated with mycobacterial diseases in developing countries where tuberculosis prevalence is high and access to HAART is currently expanding.

Fulminant inflammatory leukoencephalopathy associated with HAART-induced immune restoration in AIDS-related progressive multifocal leukoencephalopathy

HAART-induced immune restoration is beneficial for patients with AIDS-related progressive multifocal leukoencephalopathy (PML). However, in rare instances, an immune-reconstitution inflammatory syndrome (IRIS) may cause paradoxical clinical deterioration. We report the neuropathological study of an AIDS patient who presented with progressive cognitive deterioration; CD4(+) count was 117 and the HIV viral load >10(4); imaging showed non-enhancing lesions consistent with PML. Following initiation of HAART, CD4(+) was 300 and HIV viral load <10(3), but his neurological symptoms continued to deteriorate. Imaging revealed an increase in the size and number of lesions and enhancement of all the lesions. A stereotactic biopsy showed severe inflammatory and demyelinating lesions with marked infiltration by macrophages and T lymphocytes in the absence of a detectable infectious agent. Despite high doses of steroids, the patient died 3 months after admission. Autopsy showed two types of lesions: (1) active inflammatory PML changes with abundant JC virus, and intraparenchymal and perivascular infiltration by T lymphocytes, and (2) acute perivenous leukoencephalitis devoid of JC virus. Most lymphocytes were CD8(+) lymphocytes; CD4(+) lymphocytes were virtually absent. Two pathological reactions were associated with the paradoxical clinical deterioration related to dysregulation of the immune response characteristic of IRIS in PML: (1) an accentuation of JCV infection, and (2) a nonspecific acute perivenous leukoencephalitis. We suggest that both these types of lesions are due to an imbalance of CD8(+)/CD4(+) T cells, with massive infiltration of the cerebral parenchyma by CD8(+) cytotoxic T lymphocytes in the absence of sufficient CD4(+) response. Better understanding of the mechanisms of the IRIS may enable prevention or cure of this severe, sometimes fatal complication of HAART.

A decade surveillance study of Mycobacterium xenopi disease and antimicrobial susceptibility levels in a reference teaching hospital of northern Italy: HIV-associated versus non-HIV-associated infection

OBJECTIVE AND METHOD

The aim of our survey is to investigate the epidemiology and in vitro antimicrobial susceptibility levels of 35 consecutive Mycobacterium xenopi strains responsible for confirmed disease at a University Hospital from 1993 to 2002 and to identify eventual differences in the in vitro sensitivity profile between the 17 strains isolated from patients with HIV disease and the 18 isolates cultured from non-HIV-infected individuals.

RESULTS

The involvement of lower airways accounted for 88.6% of cases; but atypical pulmonary findings, including cavitation and a prominent inflammatory reaction, recently emerged in HIV-infected patients successfully treated with HAART, which raises the possible role of immune reconstitution syndrome in the clinical pathomorphism of this opportunistic disease. When compared with non-HIV-infected patients, patients with HIV disease had a lower mean age and a tendency to suffer from late relapses. The greatest overall in vitro sensitivity rate was registered for capreomycin and protionamide (100% of strains) followed by kanamicin (96.6%), whereas susceptibility rates for the first-line compounds such as ethambutol, isoniazid, and rifampicin were slightly lower (85.7% to 91.4%). No temporal variation in the susceptibility index was seen over the study decade. Non-HIV-infected patients experienced a higher frequency of M. xenopi isolates that proved to be resistant to at least one tested compound compared with HIV-associated episodes, despite the heavy and prolonged exposure of HIV-infected patients to broad spectrum antimicrobials, which included agents effective on atypical mycobacteria. Only one HIV-positive patient developed rifampicin resistance in his third disease recurrence.

CONCLUSION

A rapid diagnosis, a reliable differentiation between colonization and disease, and an optimal therapeutic choice for atypical mycobacterial disease (including M. xenopi one) are still serious challenges for clinicians and bacteriologists who treat immunocompromised patients, such as those with HIV disease. In the immunocompromised host, diagnostic difficulties posed by late identification and eventually concurrent opportunistic disorders add their negative effects to therapeutic problems due to the unpredictable in vitro susceptibility profile of atypical mycobacteria, such as M. xenopi.