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

The immune reconstitution inflammatory syndrome: a clinical update

The immune reconstitution inflammatory syndrome (IRIS) is a well-described phenomenon in HIV-infected patients following initiation of antiretroviral therapy and can lead to significant morbidity and mortality in some patients. Risk for IRIS is enhanced in those with low CD4 counts and preexisting opportunistic infections. The development of pathogen-specific definitions of IRIS has aided classification of patients and has facilitated research. Newer data on optimal timing of ART initiation, with additional data in the setting of tuberculosis and cryptococcal meningitis, will help guide strategies to decrease the risk of IRIS but must balance the risks of HIV disease progression. Managing patients with IRIS can be challenging. Treatment options include pathogen-specific therapy, antiinflammatory therapies, and other novel approaches.

Current advances in pharmacovigilance in the USA and Europe: meeting the challenges of safety monitoring in HIV

PURPOSE OF REVIEW

The success of antiretroviral therapy in HIV disease comes currently with the realization that patients are committed to life-long treatment, which raises the possibility of long-term toxicity. Such long-term side effects may not be identified in initial clinical trials requiring, therefore, a different approach to monitoring patients over time - a pharmacovigilance approach.

RECENT FINDINGS

Several key issues in long-term management of HIV infection have been addressed by a pharmacovigilance approach - including unusual and rare side effects and elucidation of emerging toxicities such as cardiovascular, bone and renal disease. Recent changes in legislation in the USA and Europe are aimed to strengthen pharmacovigilance in developed countries.

SUMMARY

HIV infection and its treatment provide an important example of the role of pharmacovigilance. As clinical trials can rarely address the question of long-term tolerability, effective pharmacovigilance programs are and will remain essential.

Modulation of host cell signaling pathways as a therapeutic approach in periodontal disease

Recently, new treatment approaches have been developed to target the host component of periodontal disease. This review aims at providing updated information on host-modulating therapies, focusing on treatment strategies for inhibiting signal transduction pathways involved in inflammation. Pharmacological inhibitors of MAPK, NFκB and JAK/STAT pathways are being developed to manage rheumatoid arthritis, periodontal disease and other inflammatory diseases. Through these agents, inflammatory mediators can be inhibited at cell signaling level, interfering on transcription factors activation and inflammatory gene expression. Although these drugs offer great potential to modulate host response, their main limitations are lack of specificity and developments of side effects. After overcoming these limitations, adjunctive host modulating drugs will provide new therapeutic strategies for periodontal treatment.

AIDS associated tuberculosis: a catastrophic collision to evade the host immune system

Human immunodeficiency virus (HIV) is a causative agent of AIDS while Mycobacterium tuberculosis causes human tuberculosis, independently. HIV and M. tuberculosis co-infection is an intriguing immunopathological phenomenon. The effect is not simply an additive but far more than that. This review gives an account of how various host and pathogen specific factors interplay to make this co-infection one of the worst co-infection, rightly named as medical "double jeopardy". We have attempted to recount some of the immune mechanisms how both these pathogens disturb the balance of host immune system resulting into defects in the host phagocytic response, leading to apoptosis and chemokine dysregulation. The HIV provides protected shelter to the M. tuberculosis and M. tuberculosis provides conducive atmosphere through the interplay of various chemokines. We also touch upon the treatment associated complications like Immune reconstitution inflammatory syndrome (IRIS) these patients face.

Acute poststreptococcal glomerulonephritis: a manifestation of immune reconstitution inflammatory syndrome

Immune reconstitution inflammatory syndrome (IRIS) is a well-described complication of initiation of highly active antiretroviral therapy in HIV-infected patients. As the immune system recovers, an inappropriate inflammatory response often occurs that causes significant disease. It is most commonly seen in patients naïve to therapy with CD4+ T-lymphocyte counts <100 cells/cmm and usually presents as a flare of mycobacterial, cytomegalovirus, or herpes zoster infections. Less commonly, this syndrome occurs in response to noninfectious triggers and results in autoimmune or malignant disease. Here we present the first case of acute poststreptococcal glomerulonephritis associated with varicella zoster virus and IRIS in an adolescent with perinatally acquired HIV and hepatitis C virus infections. Our patient was not naïve to therapy but was starting a new regimen of therapy because of virologic failure and had a relatively high CD4+ T-lymphocyte count. This case report indicates that IRIS remains a concern after initiation of a new highly active antiretroviral therapy regimen in HIV-infected patients with high viral loads, even in the presence of CD4+ T-lymphocyte counts >100 cells/cmm. It may present as infectious, malignant, or autoimmune conditions including poststreptococcal glomerulonephritis.

CNS-immune reconstitution inflammatory syndrome in the setting of HIV infection, part 1: overview and discussion of progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome and cryptococcal-immune reconstitution inflammatory syndrome

SUMMARY

While uncommon, CNS-IRIS developing after the initiation of HAART in the setting of HIV-related severe immunosuppression is characterized by an intense inflammatory reaction to dead or latent organisms or to self-antigens due to a heightened but dysregulated immune response. While this reaction can range from mild to fulminating, encompassing a very wide clinical spectrum, it is important to recognize because changes in medical management may be necessary to prevent neurologic decline and even death. Once contained, however, this inflammatory response can be associated with improved patient outcome as immune function is restored. Among the infectious organisms that are most commonly associated with CNS-IRIS are the JC virus and Cryptococcus organisms, which will be the subject of this review. CD8 cell infiltration in the leptomeninges, perivascular spaces, blood vessels, and even parenchyma seems to be the pathologic hallmark of CNS-IRIS. While recognition of CNS-IRIS may be difficult, the onset of new or progressive clinical symptoms, despite medical therapy and despite improved laboratory data, and the appearance on neuroimaging studies of contrast enhancement, interstitial edema, mass effect, and restricted diffusion in infections not typically characterized by these findings in the untreated HIV-infected patient should raise the strong suspicion for CNS-IRIS. While CNS-IRIS is a diagnosis of exclusion, the neuroradiologist can play a critical role in alerting the clinician to the possibility of this syndrome.

Heart failure and cardiogenic shock associated with the TB-immune reconstitution inflammatory syndrome

Heart failure has not been described in the setting of TB-immune reconstitution inflammatory syndrome (IRIS). We describe a case of cardiogenic shock in the setting of TB-IRIS four weeks after commencement of antiretroviral therapy. Possible aetiologies and pathophysiology as well as suggested diagnostic and therapeutic approaches to this problem are discussed.

Head and neck manifestations of the immune reconstitution syndrome in HIV-infected patients: a cohort study

OBJECTIVE

To describe head and neck manifestations of immune reconstitution inflammatory syndrome (IRIS) in a cohort of HIV-infected patients receiving combined antiretroviral therapy (cART). After initiation of cART, some HIV-infected patients present a paradoxical worsening and clinical deterioration due to pathological inflammatory reactions to infectious or noninfectious antigens, a condition known as IRIS.

STUDY DESIGN

Prospective study with a follow-up period of 6 to 24 months.

SETTING

Tertiary referral center in Mexico City.

METHODS

Our cohort was integrated by 165 patients who had started cART within the past 2 months prior to study entry. Patients underwent a complete ear, nose, and throat examination (ENT). Laboratory tests (hematology and blood chemistry), cultures from body fluids, and biopsies were performed.

RESULTS

Of the 165 patients studied, 21 (12.7%) presented IRIS in the head and neck region. Kaposi sarcoma was the most common presentation, observed in 7 patients. Tuberculosis-associated IRIS was observed in 6 patients with scrophulas, lymph node enlargement, or retropharyngeal abscess. Other manifestations included herpes simplex I infection and unilateral vocal fold palsy secondary to Mycobacterium avium intracelulare paratracheal abscess and scrophulas, as well as cervical lymph node histoplasmosis and facial palsy.

CONCLUSIONS

To our knowledge, this is the first prospective study describing the different manifestations of IRIS in the head and neck region.

Role of endogenous biological response modifiers in pathogenesis of infectious diseases

Biologic response modifiers (BRMs) interact with the host immune system and modify the immune response. BRMs can be therapeutically used to restore, augment, or dampen the host immune response. Although they have been used for decades, their clinical applications have been expanded in the past decade for diagnosis and treatment of many diseases including cancers, immunologic disorders, and infections. This article discusses endogenous biological response modifiers (ie, naturally occurring immunomodulators as a part of the host immune system), which play vital roles as regulators of both innate and adaptive immune responses.

Side Effects of the Immune System: Lessons from Tuberculosis-Related Immune Reconstitution Inflammatory Syndrome

Immune reconstitution inflammatory syndrome (IRIS) is a recently described syndrome among human immunodeficiency virus (HIV)-infected patients attributable to the recovery of the immune system during antiretroviral therapy. A growing number of researches on this syndrome have been conducted in recent years, but IRIS in children has not been widely studied. We report the case of a 4.5 month-old, tuberculosis (TB)-HIV co-infected girl who developed IRIS two months after beginning antiretroviral and anti-TB medications. We moreover review the immunopathogenesis of TB-HIV coinfection and IRIS, with particular regard to TB-related IRIS.

Immune reconstitution inflammatory syndrome in HIV-infected patients: what a critical-care nurse needs to know

Immune reconstitution inflammatory syndrome is a constellation of clinical manifestations seen in patients with HIV/AIDS who are taking highly active antiretroviral therapy. The revitalization of their immune systems by these medications leads to the emergence of opportunistic infections that had been treated previously and those never treated. Some of these diseases have serious ramifications if undetected. To care for these patients, the critical-care nurse must be aware of their presentation and treatment.

Immune reconstitution is not a prognostic factor in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is typically associated with minimal inflammation; however, patients may develop an inflammatory response due to immune reconstitution (IRIS). The authors aimed to determine if characteristics and outcomes of PML are altered in those with IRIS. A retrospective records review was performed on 87 patients diagnosed with PML at Johns Hopkins, 27 of which had a syndrome consistent with IRIS. Gadolinium enhancement on MRI occurred in 44.4% of cases of PML-IRIS versus 5.1% in PML (p<0.05), and thus had low diagnostic sensitivity and specificity. In HIV+ cases, CD4 counts were lower in those who later developed IRIS (mean 34.8 vs. 71.7, p<0.05) and was predictive of the development of IRIS (p<0.05). Improved prognosis was seen with higher cerebrospinal fluid (CSF) white blood cell counts and protein levels, but not for gadolinium enhancement and there were no differences in survival for PML versus PML-IRIS.

An unusual cause of chest pain: Mycobacterium avium complex and the immune reconstitution inflammatory syndrome

The HIV-associated immune reconstitution inflammatory syndrome usually manifests as new infections or worsening of pre-existing infections during the first few months of initiating anti-retroviral therapy. It is commonly associated with local or systemic inflammation, presumably due to rapid reconstitution of host immune system. Here we describe a unique case of the immune reconstitution inflammatory syndrome presenting as acute pericarditis and pericardial effusion caused by mycobacterium avium complex. We also demonstrate that judicious use of steroids, along with pathogen specific antimicrobial therapy, can prevent local complications of the inflammatory response.

Immune Reconstitution Inflammatory Syndrome

Immune reconstitution inflammatory syndrome (IRIS) is a phenomenon observed in patients recovering from immunodeficiency. The clinical presentation of IRIS involves the unmasking of covert infections or the worsening of overt conditions. Several causes and pathways have been suggested, most recognizing an inflammatory flare component occurring in the context of rapid immune reconstitution. In HIV-infected patients, IRIS inadvertently occurs as the consequence of successful antiretroviral therapy, and it is affiliated with improvement of the immune function, complicating the course of the disease and presenting treatment challenges to clinicians. The pathogenesis of IRIS is poorly understood, but in recovering HIV patients, its initiation and progression seem to be primarily linked to an increase in CD4+ T-helper and CD8+ T-suppressor cell count and a reduction in T-regulatory cells, all endorsed by exaggerated cytokine release and activity. The clinical presentation of IRIS is usually atypical. The manifestations depend on the trigger antigen, which can be an infective agent (viable or nonviable), a host antigen, or a tumor antigen. Most IRIS cases are self-limiting, but a few cases can be overwhelming and life-threatening; hence, early recognition is important. In most cases, there is no need to discontinue the antiretroviral therapy, although in the more severe cases, other clinical intervention may be necessary.

Clinical Markers of Immunodeficiency and Mechanism of Immune Reconstitution Inflammatory Syndrome and Highly Active Antiretroviral Therapy on HIV

Antiretroviral therapy (ART) has improved survival and changed the disease pattern of HIV infection. However, ART may cause serious side effects, such as metabolic and cardiovascular complications. In addition, immune reconstitution inflammatory syndrome (IRIS) is being increasingly reported in relation to ART. The article presents the consensus of a workshop around 4 key issues: (1) the differences in the response of adults and children to highly active antiretroviral therapy, (2) the mechanism of the new HIV entry inhibitors and its effect on oral markers, (3) the pathogenesis of IRIS and the contradictory findings of the possible oral lesions related with IRIS, (4) and the benefits and barriers associated with using ART in the developing and developed world. The consensus of the workshop was that there is a need for future studies on the oral manifestations of HIV in individuals treated with new ARTs—especially, children. IRIS was considered a promising field for future research; as such, workshop attendees recommended formulating an IRIS–oral lesions case definition and following strict criteria for its diagnosis.

Cardiac effects of antiretroviral therapy in HIV-negative infants born to HIV-positive mothers: NHLBI CHAART-1 (National Heart, Lung, and Blood Institute Cardiovascular Status of HAART Therapy in HIV-Exposed Infants and Children cohort study)

OBJECTIVES

The aim of this study was to investigate the possible effects of antiretroviral therapy (ART) in utero on cardiac development and function in human immunodeficiency virus (HIV)-negative children.

BACKGROUND

ART reduces vertical HIV transmission. Long-term cardiotoxicity after in utero exposure to ART is unknown in children but has occurred in young animals.

METHODS

Using a prospective multisite cohort study design, echocardiograms taken between birth and 24 months were compared in 2 groups of HIV-negative infants of HIV-positive mothers: 136 infants exposed to ART (ART+) and 216 unexposed infants (ART-).

RESULTS

Mean left ventricular (LV) mass z-scores were consistently lower in ART+ girls than in ART- girls: differences in mean z-scores were -0.46 at birth (p = 0.005), -1.02 at 6 months (p < 0.001), -0.74 at 12 months (p < 0.001), and -0.79 at 24 months (p < 0.001). Corresponding differences in z-scores for boys were smaller: 0.13 at 1 month (p = 0.42), -0.44 at 6 months (p = 0.01), -0.15 at 12 months (p = 0.37), and -0.21 at 24 months (p = 0.21). Septal wall thickness and LV dimension were smaller than expected in ART+ infants, but LV contractility was consistently about 1 SD higher at all ages (p < 0.001). In ART+ infants, LV fractional shortening was higher than in ART- infants; girls showed a greater difference.

CONCLUSIONS

Fetal exposure to ART is associated with reduced LV mass, LV dimension, and septal wall thickness z-scores and increased LV fractional shortening and contractility up to age 2 years. These effects are more pronounced in girls than in boys. Fetal ART exposure may impair myocardial growth while improving depressed LV function.

Immune reconstitution after a decade of combined antiretroviral therapies for human immunodeficiency virus

The introduction of combined antiretroviral therapies (HAART) has reversed the fatal course of human immunodeficiency virus (HIV) infection. HAART controls virus production and, in most cases, allows the quantitative and functional immune defects caused by HIV to be reversed. Here, we review T cell homeostatic mechanisms that drive immune recovery. These homeostatic mechanisms, as well as differences in T cell antigen exposure, explain the distinct patterns of recovery for HIV-specific T cells versus T cells specific for other pathogens. Immune restoration during HAART can, however, have adverse effects. Immune restoration syndrome occurs in some patients as a result of successful but unbalanced immunity.

Novel developments in the epidemic of human immunodeficiency virus and tuberculosis coinfection

Tuberculosis (TB) disease remains one of the highest causes of mortality in HIV-infected individuals, and HIV-TB coinfection continues to grow at alarming rates, especially in sub-Saharan Africa. Surprisingly, a number of important areas regarding coinfection remain unclear. For example, increased risk of TB disease begins early in the course of HIV infection; however, the mechanism by which HIV increases this risk is not well understood. In addition, there is lack of consensus on the optimal way to diagnose latent TB infection and to manage active disease in those who are HIV infected. Furthermore, effective point-of-care testing for TB disease remains elusive. This review discusses key areas in the epidemiology, pathogenesis, diagnosis, and management of active and latent TB in those infected with HIV, focusing attention on issues related to high- and low-burden areas. Particular emphasis is placed on controversial areas where there are gaps in knowledge and on future directions of study.

Penicillium marneffei infection presenting as an immune reconstitution inflammatory syndrome in an HIV patient

We describe a case of Penicillium marneffei infection acquired in Thailand, manifesting as an immune reconstitution inflammatory syndrome (IRIS) in a Caucasian man with advanced HIV-related immunosuppression (CD4 72 cells/mm3). Initial presentation was consistent with Pneumocystis jirovecii pneumonia, and empirical co-trimoxazole resulted in clinical improvement. One month after initiating antiretroviral therapy (ART), an enlarging scaly lesion on his forehead and erythematous nodules on his face, trunk and limbs developed. P. marneffei was isolated from a skin aspirate. Response to antifungal therapy was complicated by drug interactions but cure was complete after four months of treatment. Few cases of IRIS associated with P. marneffei have been reported.

Immune reconstitution inflammatory syndrome in AIDS-related non-hodgkin's lymphoma

Immune Reconstitution syndrome following antiretroviral therapy is common in HIV/AIDS patients due to boosting of immunity. A case is reported here wherein AIDS-related Non-Hodgkin‘s lymphoma patient received CHOP regimen and antiretroviral therapy. Patient developed tubercular lymphadenopathy paradoxically as a manifestation of IRIS.

HIV-Associated Tuberculosis

The intersecting HIV and Tuberculosis epidemics in countries with a high disease burden of both infections pose many challenges and opportunities. For patients infected with HIV in high TB burden countries, the diagnosis of TB, ARV drug choices in treating HIV-TB coinfected patients, when to initiate ARV treatment in relation to TB treatment, managing immune reconstitution, minimising risk of getting infected with TB and/or managing recurrent TB, minimizing airborne transmission, and infection control are key issues. In addition, given the disproportionate burden of HIV in women in these settings, sexual reproductive health issues and particular high mortality rates associated with TB during pregnancy are important. The scaleup and resource allocation to access antiretroviral treatment in these high HIV and TB settings provide a unique opportunity to strengthen both services and impact positively in meeting Millennium Development Goal 6.

Severe leukoencephalopathy with fulminant cerebral edema reflecting immune reconstitution inflammatory syndrome during HIV infection: a case report

Introduction

Immune reconstitution inflammatory syndrome is a well-known complication in HIV-infected patients after initiation of highly active antiretroviral therapy resulting in rapid CD4⁺ cell count recovery and suppression of viral load. Generally, immune reconstitution inflammatory syndrome is based on opportunistic infections, but rare cases of immune reconstitution inflammatory syndrome inducing demyelinization of the nervous system have also been observed.

Case presentation

A 37-year-old African woman with HIV infection diagnosed at 13 years of age was admitted to the emergency department after experiencing backache, severe headache, acute aphasia and psychomotor slowing for one week. Nine weeks earlier, highly active antiretroviral therapy in this patient had been changed because of loss of efficacy, and a rapid increase in CD4⁺ cell count and decrease of HIV viral load were observed. Magnetic resonance imaging of the brain showed extensive white matter lesions, and analysis of cerebrospinal fluid revealed an immunoreactive syndrome. Intensive investigations detected no opportunistic infections. A salvage therapy, including osmotherapy, corticosteroids and treatment of epileptic seizures, was performed, but the patient died from brainstem herniation 48 hours after admission. Neuropathologic examination of the brain revealed diffuse swelling, leptomeningeal infiltration by CD8 cells and enhancement of perivascular spaces by CD8+ cells.

Conclusion

Immune reconstitution inflammatory syndrome in this form seems to represent a severe autoimmunologic disease of the brain with specific histopathologic findings. This form of immune reconstitution inflammatory syndrome did not respond to therapy, and extremely rapid deterioration led to death within two days. Immune reconstitution inflammatory syndrome may also occur as severe leukoencephalopathy with fulminant cerebral edema during HIV infection with rapid immune reconstitution.

Castleman's disease--a two compartment model of HHV8 infection

Castleman's disease is a primary infectious disease of the lymph node that causes local symptoms or a systemic inflammatory syndrome. Histopathology reveals a destroyed lymph node architecture that can range from hyaline-vascular disease to plasma-cell disease. Viral interleukin 6 (vIL-6) produced during the replication of human herpesvirus type 8 (HHV8) is the key driver of systemic inflammation and cellular proliferation. Stage progression of Castleman's disease results from switches between viral latency and lytic replication, and lymphatic and hematogenous spread. Multicentric plasma-cell disease in HIV-1 patients is associated with HHV8 infection. Polyclonal plasmablast proliferation escapes control in the germinal center with eventual malignant transformation into non-Hodgkin lymphoma. Surgery produces excellent results in unicentric disease, while multicentric disease responds to anti-CD20 therapy or IL-6 and chemotherapy. Lymphovascular endothelium and naive B cells are infectious reservoir-opening options for antiangiogenic and anti-CD19 strategies to enhance outcomes in patients with systemic disease.

Urine for the diagnosis of tuberculosis: current approaches, clinical applicability, and new developments

PURPOSE OF REVIEW

Urine is increasingly being investigated as a convenient clinical sample for the identification of mycobacterial products for the diagnosis of tuberculosis. The available literature on mycobacterial lipoarabinomannan (LAM) and urine mycobacterial DNA is reviewed.

RECENT FINDINGS

The available data, despite being extracted from heterogeneous clinical populations and different clinical subgroups, indicate that urine LAM has little diagnostic utility in unselected tuberculosis suspects; however, test characteristics improve in HIV-infected patients, particularly those with advanced immunosuppression (CD4 cell count <200 cells/microl). Methodologies for urine PCR for detection of mycobacterial DNA vary across studies and focus is on standardizing assays with respect to specimen collection, assay design, and processing methodology.

SUMMARY

Both the urine LAM and PCR for mycobacterial DNA are being evaluated in different geographical settings. Urine LAM currently offers little utility for the diagnosis of tuberculosis in unselected populations. However, urine LAM appears promising as a diagnostic tool in HIV-infected patients with CD4 cell counts less than 200 cells/microl in different clinical settings. Further developmental studies are required to enhance the performance of the assays, and their usefulness over sputum microscopy in HIV-infected patients with advanced immunosuppression requires definition in large cohort studies.

Global lung health: the colliding epidemics of tuberculosis, tobacco smoking, HIV and COPD

Tuberculosis (TB), smoking, HIV and chronic obstructive pulmonary disease (COPD) are burgeoning epidemics in developing countries. The link between TB and HIV is well established. Less well recognised is the strong relationship between tobacco smoking and the development and natural history of TB. These associations are of considerable relevance to public health and disease outcomes in individuals with TB. Moreover, tobacco smoking, a modifiable risk factor, is associated with poorer outcomes in HIV-associated opportunistic infections, of which TB is the commonest in developing countries. It is now also becoming clear that TB, like tobacco smoke, besides its known consequences of bronchiectasis and other pulmonary morbidity, is also a significant risk factor for the development of COPD. Thus, there is a deleterious and synergistic interaction between TB, HIV, tobacco smoking and COPD in a large proportion of the world's population. Further work, specifically mechanistic and epidemiological studies, is required to clarify the role of tobacco smoke on the progression of TB and HIV infection, and to assess the impact of smoking cessation interventions. These interactions deserve urgent attention and have major implications for coordinated public health planning and policy recommendations in the developing world.

Tuberculosis-associated immune reconstitution inflammatory syndrome and unmasking of tuberculosis by antiretroviral therapy

The tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a frequent early complication of antiretroviral therapy (ART), used to treat HIV-1 infection, especially in countries where TB is prevalent. TB-IRIS is characterized by an exaggerated inflammatory response toward the antigens of Mycobacterium tuberculosis that results in clinical deterioration in patients experiencing immune recovery during early ART. Two forms of TB-IRIS are recognized: paradoxical; and unmasking. Paradoxical TB-IRIS manifests with new or recurrent TB symptoms or signs in patients being treated for TB during early ART, and unmasking TB-IRIS is characterized by an exaggerated, unusually inflammatory initial presentation of TB during early ART. In this review the incidence, clinical features, risk factors, treatment, and prevention of TB-IRIS in adult and pediatric patients are discussed.

Immune restoration diseases reflect diverse immunopathological mechanisms

Up to one in four patients infected with human immunodeficiency virus type 1 and given antiretroviral therapy (ART) experiences inflammatory or cellular proliferative disease associated with a preexisting opportunistic infection, which may be subclinical. These immune restoration diseases (IRD) appear to result from the restoration of immunocompetence. IRD associated with intracellular pathogens are characterized by cellular immune responses and/or granulomatous inflammation. Mycobacterial and cryptococcal IRD are attributed to a pathological overproduction of Th1 cytokines. Clinicopathological characteristics of IRD associated with viral infections suggest different pathogenic mechanisms. For example, IRD associated with varicella-zoster virus or JC polyomavirus infection correlate with a CD8 T-cell response in the central nervous system. Exacerbations or de novo presentations of hepatitis associated with hepatitis C virus (HCV) infection following ART may also reflect restoration of pathogen-specific immune responses as titers of HCV-reactive antibodies rise in parallel with liver enzymes and plasma markers of T-cell activation. Correlations between immunological parameters assessed in longitudinal sample sets and clinical presentations are required to illuminate the diverse immunological scenarios described collectively as IRD. Here we present salient clinical features and review progress toward understanding their pathogeneses.

Immunopathogenesis of immune reconstitution disease in HIV patients responding to antiretroviral therapy

PURPOSE OF REVIEW

The aim of this article is to review the most recent literature regarding the immunopathogenesis of pathogen-associated immune reconstitution disease and to discuss the role of immune activation and various effector molecules and cells such as macrophages, effector and regulatory T cells, and natural killer cells in immune reconstitution disease.

RECENT FINDINGS

Many HIV patients receiving antiretroviral treatment develop immune reconstitution disease, which is characterized by exaggerated inflammatory immune responses to replicating or dead pathogens. In the majority of these cases, immune reconstitution disease is associated with restoration of pathogen-specific cellular immune responses involving CD4 or CD8 effector T cells. The precise conditions that trigger immune reconstitution disease have not yet been identified. Immune reconstitution disease patients have overt immune activation, which may be due to poor homeostatic control after the fast initial immune recovery in patients receiving antiretroviral therapy. Poor homeostatic control in immune reconstitution disease patients may be linked to unbalanced restoration of effector and regulatory T cells.

SUMMARY

Although the precise mechanism of immune reconstitution disease is not well understood, it is probably related to rapid restoration of pathogen-specific immune responses and poor homeostatic control that promote exaggerated immunopathological responses, especially if viable pathogens or pathogen debris are present at high concentrations.

[Immune reconstitution inflammatory syndrome and treatment of HIV infection]

BACKGROUND

HAART (highly active antiretroviral therapy) may trigger a condition known as IRIS (immune reconstitution inflammatory syndrome); i.e. a paradoxical reaction to latent infections associated with reconstitution of the immune system. The article provides an overview of the syndrome and discusses diagnosis, risk factors and management.

MATERIAL AND METHODS

The basis for the article was literature identified through non-systematic searches in PubMed and clinical experience.

RESULTS

IRIS typically occurs some weeks to months after initiation of HAART, usually in association with mycobacterial infections, cytomegalovirus, Cryptococcus neoformans and Pneumocystis jirovecii. In principle, any pathogen may cause a similar inflammatory response. Risk factors for IRIS include severe immunodeficiency, high antigen burden and rapid immune response to HAART. The prognosis is good. However, treatment of infections must not delay the initiation of HAART, as such a delay may increase morbidity and mortality. HAART should be continued unless symptoms are life-threatening or likely to cause permanent sequelae. Corticosteroids may be helpful in cases with lesions in the central nervous system, obstructive lymph nodes or increasing respiratory symptoms.

INTERPRETATION

Treatment of HIV infection has improved substantially, which implies an increased number of patients developing IRIS. A quick diagnosis and correct and timely treatment of opportunistic infections is important for the prognosis.

[Severe aseptic leucoencephalopathy. Manifested as immune reconstitution inflammatory syndrome in Caucasian and African patients]

BACKGROUND

We hypothesize that CNS immune reconstitution inflammatory syndrome (IRIS) after highly active antiretroviral therapy (HAART) in HIV-1-positive patients may become manifest without any opportunistic infection as an aseptic leucoencephalopathy. This opens a window of opportunity for successful treatment with corticosteroids.

DESIGN

We describe a case series of immunocompromised HIV-1-positive patients who were started on HAART. All of them had clinical laboratory follow-up tests and cerebral MRI in order to investigate the course and the underlying pathophysiology of this aseptic form of IRIS. One African patient died and we performed a neuropathological examination.

RESULTS

No infectious agent was detected before and during HAART. Three of four immunocompromised patients were successfully treated with corticosteroids while HAART was never interrupted and have survived up to now. One African patient died within 2 days despite intensive care due to cerebral oedema.

CONCLUSIONS

Starting HAART, HIV-1-positive patients may develop an aseptic type of IRIS of the CNS without any detectable opportunistic infection, a finding that has not yet been published. This makes them susceptible for successful treatment with corticosteroids. Perhaps IRIS has a higher incidence in African patients and the patients have a poorer outcome than Caucasians.

Immunologic markers as predictors of tuberculosis-associated immune reconstitution inflammatory syndrome in HIV and tuberculosis coinfected persons in Thailand

This study analyzes immunologic markers to predict and diagnose tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) in HIV and TB coinfected adults who initiated antiretroviral therapy (ART) in Thailand. T helper 1 cytokines interleukin (IL)-2, IL-12, and interferon-gamma (IFN-gamma) levels in response to PPD and RD1 antigens were assessed prior to ART, at weeks 6, 12, and 24 of treatment, and at time of TB-IRIS. Of 126 subjects, 22 (17.5%) developed TB-IRIS; 14 (64%) subjects received steroid treatment and 3 (14%) received NSAIDs; none of the subjects died. Median interval between ART initiation and TB-IRIS development was 14 days. IFN-gamma, IL-2, and IL-12 responses did not differ between TB-IRIS and no TB-IRIS subjects (p > 0.05). More research into the immunopathogenesis of TB-IRIS and diagnostic potential of cytokine markers is warranted.

Tuberculosis-associated immune restoration syndrome in HIV-1-infected patients involves tuberculin-specific CD4 Th1 cells and KIR-negative gammadelta T cells

Tuberculosis (TB)-associated immune restoration syndrome (IRS) is a frequent event (10 to 30%) in HIV-1-infected patients receiving antiretroviral treatment and is associated with an increased number of IFN-gamma-producing tuberculin-specific cells. To further understand the immune mechanisms of TB-IRS and to identify predictive factors, we prospectively analyzed the Th1 and TCRgammadelta T cells known to be involved in mycobacterial defenses and dendritic cells at baseline and after antiretroviral and TB treatment in 24 HIV-1(+) patients, 11 with and 13 without IRS. At baseline, these two groups differed by significantly lower proportions of TCRgammadelta and Vdelta2(+) T cells displaying the inhibitory receptors CD94/NKG2 and CD158ah,b in IRS patients. The two groups did not differ in the baseline characteristics of CD8 or CD4 T cells or TLR-2 expression on monocytes or myeloid/plasmacytoid dendritic cells. During IRS, the increase in tuberculin-specific IFN-gamma-producing cells involved only highly activated effector memory multifunctional (IFN-gamma(+)TNF-alpha(+)IL-2(-)) CD4 T cells, whereas activated HLA-DR(+) CD4(+) T cells also increased during IRS. In contrast, dendritic cells decreased significantly during IRS and there were no changes in TLR-2 expression. Finally, the Vdelta2(+) T cells, mostly killer Ig-related receptor (KIR) (CD94/NKG2(-) and CD158(-)), significantly peaked during IRS but not in non-IRS patients. In conclusion, IRS is associated with an increase in the number of activated tuberculin-specific effector memory CD4 T cells and of KIR(-)Vdelta2(+) TCRgammadelta(+) T cells. Higher proportions of Vdelta2(+)TCRgammadelta(+) T cells lacking KIR expression are present as baseline and distinguish patients who will develop IRS from those who will not.

The pathophysiology of the acute phase of human bartonellosis resembles AIDS

Human bartonellosis is a South American anthroponosis caused by Bartonella bacilliformis. The disease has an acute phase characterized by invasion of red blood cells by parasites, and consequent severe anemia; and a chronic phase presenting with benign vascular tumors. During the acute phase, affected individuals are prone to developing opportunistic infections with a variety of organisms similar to the ones seen in AIDS. After antibiotic treatment is instituted, a subgroup of patients may develop atypical symptoms which potentially represent clinical manifestations of the restoration of macrophage function. We speculate that the pathophysiology of the acute phase of human bartonellosis resembles AIDS, with a period of immunosuppression following the infection and later, clinical manifestations of immune reconstitution subsequent to treatment.

Malignant solid tumour, HIV infection and tuberculosis in children: an unholy triad

INTRODUCTION

Co-morbidities introduce confounding variables into investigational protocols and complicate both diagnosis and management of children with malignant solid tumours. Such patients who are coincidentally HIV infected and who also have pulmonary or abdominal tuberculosis pose a particular challenge.

AIM

The purpose of this report is to describe the diagnostic and management difficulties encountered in a small cadre of 18 HIV-infected children with solid tumours presenting to the Department of Paediatric Surgery.

METHOD

A retrospective descriptive study of HIV-infected children with malignant solid tumours.

RESULTS

18 HIV-infected children were identified with a variety of primary tumours. 11 children had confirmed pulmonary or abdominal tuberculosis and in 4 the diagnosis was suspected. Neoadjuvant chemotherapy was used when possible to provide a window of opportunity to investigate co-morbidity and improve health status, inter alia, improving the patients' nutritional status. FDG-PET scanning proved unreliable in discriminating between malignant and inflammatory pathology. Overall survival was 33%.

CONCLUSION

The coincidence of malignancy, HIV infection and tuberculosis carries a high mortality independent of the primary tumour type.

Pediatric TB: issues related to current and future treatment options

Pediatric TB continues to be a neglected disease in many endemic areas where limited resources restrict the focus of treatment to only the most infectious TB cases. However, recognition that children contribute to a significant proportion of the global TB disease burden and suffer severe TB-related morbidity and mortality is growing. The WHO published guidelines on the management of pediatric TB in 2006 and child-friendly drug formulations have been made available to deserving low-income nations via the Global Drug Fund since 2008. Increased awareness and improved drug availability re-emphasized the considerable programmatic barriers that remain and the difficulty of establishing an accurate diagnosis in resource-limited settings. This article provides an overview of current treatment practices, factors that influence the provision of effective TB therapy to children in endemic areas and potential future advances. It includes a brief summary of the relevant literature and presents the authors’ personal perspectives on issues related to the treatment of pediatric TB.

Autoimmunity and HIV

PURPOSE OF REVIEW

This review focuses on some of the recent advances in the understanding of HIV immunopathogenesis and the diagnosis and treatment of several autoimmune conditions associated with HIV in the era of potent antiretroviral therapy.

RECENT FINDINGS

Chronic immune activation with progressive immune exhaustion are central features of HIV pathogenesis. The role of self-reactive T cells in the generation and maintenance of this process has recently been described. The understanding of the impact of immune dysregulation on the generation of autoimmune phenomena in HIV infection remains incomplete. The diagnosis of autoimmune diseases in the context of HIV is often difficult due to similarities in clinical presentations and laboratory markers. The antiretroviral therapy-associated immune reconstitution syndrome can present as autoimmune disease.

SUMMARY

The cause, frequency and prognosis of autoimmune conditions associated with HIV infection remain somewhat uncertain. Their management is often empirical with the use of novel immunosuppressive medication.

[Human immunodeficiency virus and AIDS-associated immune reconstitution syndrome. State of the art]

Since the arrival of highly active antiretroviral therapy (HAART), immune reconstitution syndrome (IRS) has become an increasingly more frequent complication in patients with human immunodeficiency virus (HIV) infection. This article presents a review of the available evidence on this subject, indexed in MEDLINE-PUBMED, BVS-BIREME, and BioMed Central. The review covers the definition, epidemiology, classification, and diagnostic criteria related to IRS. In addition, the clinical particularities of the most frequent etiologies are described, and a proposal for a therapeutic approach is formulated. The prognosis and future implications of this syndrome in the epidemiology of some infectious illnesses in the HIV-positive population are included. Several unresolved aspects are mentioned, such as those related to the pathophysiology of the condition, use of biomarkers for the diagnosis, and the need for evidence-based therapeutic algorithms to enable standardization of treatment for these patients.