Selective expansion of polyfunctional pathogen-specific CD4(+) T cells in HIV-1-infected patients with immune reconstitution inflammatory syndrome

An Immunological Non-responder Human Immunodeficiency Virus/Hepatitis C Virus Coinfected Patient: Considerations About a Clinical Case

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections are two chronic viral infections that share the same mode of transmission, making HIV/HCV coinfection frequent. Highly active antiretroviral therapy (HAART) was a turning point in HIV treatment and has been shown to successfully restore immune function and reduce the frequency of opportunistic infections. Despite a virological response to HAART, a proportion of patients fail to achieve substantial immune recovery, as measured by peripheral CD4 cell counts. Herein, we present the case of a patient with HIV/HCV coinfection who did not achieve successful immune function restoration despite HIV suppression and HCV treatment. Our goal is to promote discussion. Despite considerable advances in the understanding of the impact of HCV on HIV disease progression, there are many individual variables that influence a patient's immune function. In addition, we consider hypogammaglobulinemia as a possible contributor. Further understanding and improvement of immune reconstitution in patients infected with HIV remain an important field of scientific research.

Polyfunctional Antigen Specific CD4+ T cell Responses in Patients With Human Immunodeficiency Virus/AIDS and Histoplasmosis Immune Reconstitution Inflammatory Syndrome

In the combination antiretroviral era, there are limited data regarding the pathogenesis of histoplasmosis immune reconstitution inflammatory syndrome (IRIS) in people with human immunodeficiency virus (HIV). We immunologically characterized 10 cases of histoplasmosis, 4 of whom developed histoplasmosis IRIS. CD4+ T cells in histoplasmosis IRIS demonstrated a significant polyfunctional cytokine response to histoplasma antigen.

A retrospective clinical study of dolutegravir- versus efavirenz-based regimen in treatment-naïve patients with advanced HIV infection in Nanjing, China

Currently, there are limited data related to the efficacy and safety of ART regimens, as well as factors influencing immune recovery in antiretroviral therapy (ART)-naïve patients with advanced HIV infection, especially in China. We designed a single-center, retrospective cohort study from March 1, 2019, to May 31, 2022, at The Second Hospital of Nanjing, China. ART-naïve adults with advanced HIV infection (CD4+ T-cell count < 200 cells/μL) who met the study criteria were included. The plasma viral load (VL), CD4+ T-cell count, CD4/CD8 ratio, treatment discontinuation, and immune reconstitution inflammatory syndrome (IRIS) events were collected to compare the efficacy and safety of the dolutegravir (DTG) and the efavirenz (EFV) regimens. Factors of immune recovery were analyzed using the Cox regression model. Study enrolled 285 ART-naïve adults with advanced HIV-1 infection, of which 95 (33.3%) started regimens including DTG and 190 (66.7%) were treated with EFV. After ART initiation, the proportion of patients with HIV-1 RNA < 50 copies/mL was higher (22.5% versus 6.5%, P < 0.001) in those on DTG-based regimens at month 1, but no significant difference at other follow-up points. Compared to the baseline, the median CD4+ T-cell count and CD4/CD8 ratio increased significantly during follow-up both in the EFV and the DTG groups. However, the CD4+ T-cell count increased greater in patients on DTG-based regimens at months 6, 12, 24, and 36 (P < 0.05). A total of 52 (18.2%) patients discontinued treatment, with no significant difference between ART regimens in treatment discontinuation rates. Only 7 patients reported IRIS, without significant difference between ART regimens (P=0.224). Overall, 34.0% (97/285) achieved a CD4+ T-cell count ≥ 350 cells/μL during follow-up. Age (P < 0.001), baseline CD4+ T-cell count (P < 0.001), baseline VL (P < 0.001) and ART regimens (P = 0.019) were associated with the CD4+ T-cell count ≥ 350 cells/μL after adjusting for potential confounders. Among ART-naïve adults with advanced HIV infection, it appeared that DTG-based regimens were better options for initial therapy compared to regimens including EFV; in addition, ART regimens, age, baseline VL and CD4+ T-cell count were associated with immune recovery.

Phenotypic Profile of Mycobacterium tuberculosis-Specific CD4 T-Cell Responses in People With Advanced Human Immunodeficiency Virus Who Develop Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome

Background

Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a frequent complication of cotreatment for TB and human immunodeficiency virus (HIV)-1. We characterized Mycobacterium tuberculosis (Mtb)-specific CD4 T-cell phenotype and transcription factor profile associated with the development of TB-IRIS.

Methods

We examined the role of CD4 T-cell transcription factors in a murine model of mycobacterial IRIS. In humans, we used a longitudinal study design to compare the magnitude of antiretroviral therapy, activation, transcription factor profile, and cytotoxic potential of Mtb-specific CD4 T cells between TB-IRIS (n = 25) and appropriate non-IRIS control patients (n = 18) using flow cytometry.

Results

In the murine model, CD4 T-cell expression of Eomesodermin (Eomes), but not Tbet, was associated with experimentally induced IRIS. In patients, TB-IRIS onset was associated with the expansion of Mtb-specific IFNγ⁺CD4 T cells (P = .039). Patients with TB-IRIS had higher HLA-DR expression (P = .016), but no differences in the expression of T-bet or Eomes were observed. At TB-IRIS onset, Eomes⁺Tbet⁺Mtb-specific IFNγ⁺CD4⁺ T cells showed higher expression of granzyme B in patients with TB-IRIS (P = .026).

Conclusions

Although the murine model of Mycobacterium avium complex-IRIS suggests that Eomes⁺CD4 T cells underly IRIS, TB-IRIS was not associated with Eomes expression in patients. Mycobacterium tuberculosis-specific IFNγ⁺CD4 T-cell responses in TB-IRIS patients are differentiated, highly activated, and potentially cytotoxic.

Biotypes of HIV-associated neurocognitive disorders based on viral and immune pathogenesis

PURPOSE OF REVIEW

HIV-associated neurocognitive disorders (HAND) continues to be prevalent in people living with HIV despite antiretroviral therapy. However, understanding disease mechanisms and identifying therapeutic avenues has been challenging. One of the challenges is that HAND is a heterogeneous disease and that patients identified with similar impairments phenotypically may have very different underlying disease processes. As the NeuroAIDS field is re-evaluating the approaches used to identify patients with HIV-associated neurological impairments, we propose the subtyping of patients into biotypes based on viral and immune pathogenesis.

RECENT FINDINGS

Here we review the evidence supporting subtyping patients with HIV-associated neurological complications into four biotypes: macrophage-mediated HIV encephalitis, CNS viral escape, T-cell-mediated HIV encephalitis, and HIV protein-associated encephalopathy.

SUMMARY

Subtyping patients into subgroups based on biotypes has emerged as a useful approach for studying heterogeneous diseases. Understanding biotypes of HIV-associated neurocognitive impairments may therefore enable better understanding of disease mechanisms, allow for the development of prognostic and diagnostic markers, and could ultimately guide therapeutic decisions.

Advanced HIV Infection in Treatment Naïve Individuals: Effectiveness and Persistence of Recommended Three-Drug Regimens

Background

Approximately 20% of newly diagnosed people with HIV (PWH) in the United States have advanced HIV infection, yet the literature on current antiretroviral therapy (ART) options is limited. The discontinuation/modification and effectiveness of common regimens were compared among ART-naïve people with advanced HIV infection (CD4 cell count <200 cells/μL).

Methods

ART-naïve adults with advanced HIV infection initiating bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) or a boosted darunavir (bDRV)-, dolutegravir (DTG)-, or elvitegravir/cobicistat (EVG/c)-based 3-drug regimen between January 1, 2018, and July 31, 2019, in the OPERA cohort were included. The association between regimen and discontinuation or viral suppression (<50 or <200 copies/mL) was assessed using Cox proportional hazards models with inverse probability of treatment weights.

Results

Overall, 961 PWH were included (416 B/F/TAF, 106 bDRV, 271 DTG, 168 EVG/c); 70% achieved a CD4 cell count ≥200 cells/μL over a 16-month median follow-up. All regimens were associated with a statistically higher likelihood of discontinuation than B/F/TAF (bDRV: adjusted hazard ratio [aHR], 2.65; 95% CI, 1.75–4.02; DTG: aHR, 2.42; 95% CI, 1.75–3.35; EVG/c: aHR, 3.52; 95% CI, 2.44–5.07). Compared with B/F/TAF, bDRV initiators were statistically less likely to suppress to <50 copies/mL (aHR, 0.72; 95% CI, 0.52–0.99) and <200 copies/mL (aHR, 0.55; 95% CI, 0.43–0.70); no statistically significant difference was detected with DTG or EVG/c.

Conclusions

Among people with advanced HIV infection, those initiating B/F/TAF were less likely to discontinue/modify their regimen than those on any other regimen, and more likely to achieve viral suppression compared with those on bDRV but not compared with those on other integrase inhibitors.

Dynamics of T-Lymphocyte Activation Related to Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome in Persons With Advanced HIV

Most persons living with HIV (PLWH) experience a significant restoration of their immunity associated with successful inhibition of viral replication after antiretroviral therapy (ART) initiation. Nevertheless, with the robust quantitative and qualitative restoration of CD4⁺ T-lymphocytes, a fraction of patients co-infected with tuberculosis develop immune reconstitution inflammatory syndrome (TB-IRIS), a dysregulated inflammatory response that can be associated with significant tissue damage. Several studies underscored the role of adaptive immune cells in IRIS pathogenesis, but to what degree T lymphocyte activation contributes to TB-IRIS development remains largely elusive. Here, we sought to dissect the phenotypic landscape of T lymphocyte activation in PLWH coinfected with TB inititating ART, focusing on characterization of the profiles linked to development of TB-IRIS. We confirmed previous observations demonstrating that TB-IRIS individuals display pronounced CD4⁺ lymphopenia prior to ART initiation. Additionally, we found an ART-induced increase in T lymphocyte activation, proliferation and cytotoxicity among TB-IRIS patients. Importantly, we demonstrate that TB-IRIS subjects display higher frequencies of cytotoxic CD8⁺ T lymphocytes which is not affected by ART. Moreover, These patients exhibit higher levels of activated (HLA-DR⁺) and profilerative (Ki-67⁺) CD4⁺ T cells after ART commencenment than their Non-IRIS counterparts. Our network analysis reveal significant negative correlations between Total CD4⁺ T cells counts and the frequencies of Cytotoxic CD8⁺ T cells in our study population which could suggest the existance of compensatory mechanisms for Mtb-infected cells elimination in the face of severe CD4⁺ T cell lymphopenia. We also investigated the correlation between T lymphocyte activation profiles and the abundance of several inflammatory molecules in plasma. We applied unsupervised machine learning techniques to predict and diagnose TB-IRIS before and during ART. Our analyses suggest that CD4⁺ T cell activation markers are good TB-IRIS predictors, whereas the combination of CD4⁺ and CD8⁺ T cells markers are better at diagnosing TB-IRIS patients during IRIS events Overall, our findings contribute to a more refined understanding of immunological mechanisms in TB-IRIS pathogenesis that may assist in new diagnostic tools and more targeted patient management.

Strategies for the diagnosis and management of meningitis in HIV-infected adults in resource limited settings

INTRODUCTION

The incidence of human immunodeficiency virus-1 (HIV-1) associated meningitis has been declining in the post-combination antiretroviral treatment (ART) era, although survival rates remain low for the common causes like tuberculosis and cryptococcal disease. Diagnosis and treatment of meningitis in HIV-1 is complicated by atypical clinical presentations, limited accuracy of diagnostic tests, access to diagnostic tests, and therapeutic agents in low- and middle-income countries (LMIC) and immune reconstitution inflammatory syndrome (IRIS).

AREAS COVERED

We provide an overview of the common etiologies of meningitis in HIV-1-infected adults, suggest a diagnostic approach based on readily available tests, and review specific chemotherapeutic agents, host-directed therapies, supportive care, timing of ART initiation, and considerations in the management of IRIS with a focus on resource-limited settings. They identify key knowledge gaps and suggest areas for future research.

EXPERT OPINION

Evidence-based management of HIV-1-associated meningitis is sparse for common etiologies. More readily available and sensitive diagnostic tests as well as standardized investigation strategies are required in LMIC. There is a lack of availability of recommended drugs in areas of high HIV-1 prevalence and a limited pipeline of novel chemotherapeutic agents. Host-directed therapies have been inadequately studied.

Plasma Metabolomics Reveals Dysregulated Metabolic Signatures in HIV-Associated Immune Reconstitution Inflammatory Syndrome

Immune reconstitution inflammatory syndrome (IRIS) is an inflammatory complication associated with an underlying opportunistic infection that can be observed in HIV-infected individuals shortly after the initiation of antiretroviral therapy, despite successful suppression of HIV viral load and CD4⁺ T cell recovery. Better understanding of IRIS pathogenesis would allow for targeted prevention and therapeutic approaches. In this study, we sought to evaluate the metabolic perturbations in IRIS across longitudinal time points using an unbiased plasma metabolomics approach as well as integrated analyses to include plasma inflammatory biomarker profile and whole blood transcriptome. We found that many lipid and amino acid metabolites differentiated IRIS from non-IRIS conditions prior to antiretroviral therapy and during the IRIS event, implicating the association between oxidative stress, tryptophan pathway, and lipid mediated signaling and the development of IRIS. Lipid and amino acid metabolic pathways also significantly correlated with inflammatory biomarkers such as IL-12p70 and IL-8 at the IRIS event, indicating the role of cellular metabolism on cell type specific immune activation during the IRIS episode and in turn the impact of immune activation on cellular metabolism. In conclusion, we defined the metabolic profile of IRIS and revealed that perturbations in metabolism may predispose HIV-infected individuals to IRIS development and contribute to the inflammatory manifestations during the IRIS event. Furthermore, our findings expanded our current understanding IRIS pathogenesis and highlighted the significance of lipid and amino acid metabolism in inflammatory complications.

Classical complement and inflammasome activation converge in CD14highCD16- monocytes in HIV associated TB-immune reconstitution inflammatory syndrome

Inflammasome-derived cytokines, IL-1β and IL-18, and complement cascade have been independently implicated in the pathogenesis of tuberculosis (TB)-immune reconstitution inflammatory syndrome (TB-IRIS), a complication affecting HIV⁺ individuals starting antiretroviral therapy (ART). Although sublytic deposition of the membrane attack complex (MAC) has been shown to promote NLRP3 inflammasome activation, it is unknown whether these pathways may cooperatively contribute to TB-IRIS. To evaluate the activation of inflammasome, peripheral blood mononuclear cells (PBMCs) from HIV-TB co-infected patients prior to ART and at the IRIS or equivalent timepoint were incubated with a probe used to assess active caspase-1/4/5 followed by screening of ASC (apoptosis-associated speck-like protein containing a CARD domain) specks as a readout of inflammasome activation by imaging flow cytometry. We found higher numbers of monocytes showing spontaneous caspase-1/4/5⁺ASC-speck formation in TB-IRIS compared to TB non-IRIS patients. Moreover, numbers of caspase-1/4/5⁺ASC-speck⁺ monocytes positively correlated with IL-1β/IL-18 plasma levels. Besides increased systemic levels of C1q and C5a, TB-IRIS patients also showed elevated C1q and C3 deposition on monocyte cell surface, suggesting aberrant classical complement activation. A clustering tSNE analysis revealed TB-IRIS patients are enriched in a CD14^highCD16^- monocyte population that undergoes MAC deposition and caspase-1/4/5 activation compared to TB non-IRIS patients, suggesting complement-associated inflammasome activation during IRIS events. Accordingly, PBMCs from patients were more sensitive to ex-vivo complement-mediated IL-1β secretion than healthy control cells in a NLRP3-dependent manner. Therefore, our data suggest complement-associated inflammasome activation may fuel the dysregulated TB-IRIS systemic inflammatory cascade and targeting this pathway may represent a novel therapeutic approach for IRIS or related inflammatory syndromes.

Tuberculosis (TB) associated-immune reconstitution inflammatory syndrome (TB-IRIS) is a clinical complication affecting HIV⁺ individuals previously co-infected with Mycobacterium tuberculosis (Mtb), upon antiretroviral therapy (ART) initiation. TB-IRIS is characterized by an exacerbated inflammatory response and can be associated with high morbidity and mortality rates in resource-limited countries with high TB prevalence. So far, there is no targeted TB-IRIS therapy, and corticosteroids are frequently used to prevent or alleviate IRIS related-symptoms. Here we found inflammasome activation (i.e. caspase1/4/5⁺ASC speck complex formation) on circulating classical CD14^highCD16^- monocytes may contribute to TB-IRIS immunopathology, since it correlates with pro-inflammatory cytokine plasma levels and its decay is associated with dampening in IRIS-related symptoms promoted by anti-inflammatory therapy. We also found TB-IRIS monocytes display higher surface complement deposition, being more sensitive to external complement-mediated NLRP3 inflammasome activation than healthy control cells. In fact, complement MAC molecule C9 and caspase-1/4/5 activation were associated on classical monocytes in TB-IRIS patients, suggesting complement-mediated inflammasome activation may lead to a positive feedback loop in the inflammatory responses observed in TB-IRIS. Therefore, our findings support that complement-NLRP3/ASC/caspase1/4/5 axis may be considered as a potential target for host-directed therapy of TB-IRIS.

Systemic Inflammation Associated with Immune Reconstitution Inflammatory Syndrome in Persons Living with HIV

Antiretroviral therapy (ART) has represented a major advancement in the care of people living with HIV (PLWHH), resulting in significant reductions in morbidity and mortality through immune reconstitution and attenuation of homeostatic disruption. Importantly, restoration of immune function in PLWH with opportunistic infections occasionally leads to an intense and uncontrolled cytokine storm following ART initiation known as immune reconstitution inflammatory syndrome (IRIS). IRIS occurrence is associated with the severe and rapid clinical deterioration that results in significant morbidity and mortality. Here, we detail the determinants underlying IRIS development in PLWH, compiling the available knowledge in the field to highlight details of the inflammatory responses in IRIS associated with the most commonly reported opportunistic pathogens. This review also highlights gaps in the understanding of IRIS pathogenesis and summarizes therapeutic strategies that have been used for IRIS.

Lung Injury on Antiretroviral Therapy in Adults With Human Immunodeficiency Virus/Tuberculosis

BACKGROUND

Immune restoration on antiretroviral therapy (ART) can drive inflammation in people living with human immunodeficiency virus (HIV) who have pulmonary tuberculosis (TB), but its effects on the lungs have not been assessed. We evaluated associations between pulmonary inflammation, recovery of pathogen-specific CD4 T-cell function, and lung injury prior to and after ART initiation in adults with HIV and pulmonary TB.

METHODS

This was a prospective cohort study in South Africa, following adults with HIV and pulmonary TB prior to and up to 48 weeks after ART initiation. Pulmonary-specific inflammation was defined as total glycolytic activity (TGA) on [18]F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) at baseline and 4 weeks after ART initiation. Spirometry, respiratory symptom tests, and flow cytometry were performed at the same times to assess lung involvement and the frequency of mycobacteria-specific CD4 T-cells. In addition, we evaluated lung function longitudinally up to 48 weeks after ART initiation.

RESULTS

Greater lung TGA on FDG PET-CT was associated with worse lung function and respiratory symptoms prior to ART initiation, and nearly half of subjects experienced worsening lung inflammation and lung function at Week 4 of ART. Worsening Week 4 lung inflammation and pulmonary function were both associated with greater increases in pathogen-specific functional CD4 T-cell responses on ART, and early decreases in lung function were independently associated with persistently lower lung function months after TB treatment completion.

CONCLUSIONS

Increases in pulmonary inflammation and decreases in lung function are common on ART, relate to greater ART-mediated CD4 T-cell restoration, and are associated with the persistent impairment of lung function in individuals with HIV/TB.

Immune Reconstitution Inflammatory Syndrome as a Posttransplantation Complication in Primary Immunodeficiency With Disseminated Mycobacterium avium

Patients with primary immunodeficiencies undergoing allogeneic hematopoietic cell transplantation (HCT) for difficult-to-control infections can experience immune reconstitution inflammatory syndrome (IRIS) following engraftment. In 3 patients with post-HCT IRIS related to mycobacterial infection, in vitro data demonstrate the emergence of pathogen-specific immune responses and a concomitant rise in plasma inflammatory markers.

Disseminated Mycobacterium marinum in Human Immunodeficiency Virus Unmasked by Immune Reconstitution Inflammatory Syndrome

Distinguishing disseminated Mycobacterium marinum from multifocal cutaneous disease in persons with human immunodeficiency virus/AIDS can present a diagnostic challenge, especially in the context of immune reconstitution inflammatory syndrome (IRIS). In this work, we demonstrate the utility of flow cytometry and whole genome sequencing (WGS) to diagnose disseminated M. marinum unmasked by IRIS following initiation of antiretroviral therapy. Flow cytometry demonstrated robust cytokine production by CD4 T cells in response to stimulation with M. marinum lysate. WGS of isolates from distinct lesions was consistent with clonal dissemination, supporting that preexisting disseminated M. marinum disease was uncovered by inflammatory manifestations, consistent with unmasking mycobacterial IRIS.

Clinical manifestations and risk factors for oral immune reconstitution inflammatory syndrome in Mexico

The immune reconstitution inflammatory syndrome (IRIS) is a rare acute complication presenting in people living with HIV (PLWH) within the first 6 months of starting combined antiretroviral therapy (cART). While there is relevant information about its pathogenesis and clinical spectrum, IRIS-oral lesions (IRIS-OLs) have been scarcely described. Thus, to establish the incidence and clinical characteristics of IRIS-OLs, data from a cohort of 158 HIV individuals starting cART, followed for 6 months, were obtained retrospectively. IRIS-OLs developed in 11.4% of the individuals, in a median time of 87.5 days, with oral candidiasis being the most frequent manifestation detected in eight individuals (5.1%). The study emphasizes the importance of the correct diagnosis and management of these lesions.

Th1-Dependent Cryptococcus-Associated Immune Reconstitution Inflammatory Syndrome Model With Brain Damage

Cryptococcus-associated immune reconstitution inflammatory syndrome (C-IRIS) is identified upon immune reconstitution in immunocompromised patients, who have previously contracted an infection of Cryptococcus neoformans (Cn). C-IRIS can be lethal but how the immune system triggers life-threatening outcomes in patients is still poorly understood. Here, we establish a mouse model for C-IRIS with Cn serotype A strain H99, which is highly virulent and the most intensively studied. C-IRIS in mice is induced by the adoptive transfer of CD4+ T cells in immunocompromised Rag1-deficient mice infected with a low inoculum of Cn. The mice with C-IRIS exhibit symptoms which mimic clinical presentations of C-IRIS. This C-IRIS model is Th1-dependent and shows host mortality. This model is characterized with minimal lung injury, but infiltration of Th1 cells in the brain. C-IRIS mice also exhibited brain swelling with resemblance to edema and upregulation of aquaporin-4, a critical protein that regulates water flux in the brain in a Th1-dependent fashion. Our C-IRIS model may be used to advance our understanding of the paradoxical inflammatory phenomenon of C-IRIS in the context of neuroinflammation.

Effects of time of initiation of antiretroviral therapy in the treatment of patients with HIV/TB co-infection: A systemic review and meta-analysis

This systemic review and meta-analysis aimed to investigate the burden of tuberculosis immune reconstitution syndrome (TB-IRIS) and associated mortality to highlight the importance of future direction in preventing and treatment of TB-IRIS. Randomized clinical trials (RCTs) that compared early antiretroviral therapy (ART) versus late ART were included. PubMed, EMBASE, Science Direct and Cochrane Central Register of Controlled Trials electronic databases were searched. This meta-analysis included 8 RCTs with a total of 4, 425 participants. The result of analysis showed that early initiation of ART was associated with increase in TB-IRIS (RR = 1.83; 95% CI: 1.24-2.70, p = 0.002; I2 = 74%, p = 0.0007) and TB-IRIS associated mortality (RR = 6.05; 95% CI: 1.06-34.59, p = 0.04; I2 = 0%, p = 0.78). Early ART was associated with overall mortality compared with late ART initiation. Grade 3 or 4 adverse events, achieving lower viral load and development of new AIDS-defining illness were not associated with the time of ART initiation. Early ART in HIV/TB co-infected patients resulted conclusive evidence of increased TB-IRIS incidence and TB-IRIS associated mortality. Hence, the finding calls for clinical judgment as to the benefits of initiating ART earlier against the risk of TB-IRIS and associated mortality.

Immune reconstitution inflammatory syndrome in HIV infected late presenters starting integrase inhibitor containing antiretroviral therapy

BACKGROUND

Integrase inhibitors (INI) induce a rapid decline of HIV-RNA in plasma and CD4⁺ T-cell recovery in blood. Both characteristics are also associated with immune reconstitution inflammatory syndrome (IRIS). Whether the use of INI-containing combination antiretroviral therapy (cART) increases the risk of IRIS is being questioned.

METHODS

Study within the Dutch ATHENA HIV observational cohort. HIV-1 infected late presenters initiating cART after March 2009 were included if they had <200 CD4⁺ T-cells per μL and were diagnosed with an opportunistic infection. IRIS was defined either according to the criteria by French et al. (IRIS_FRENCH) or by a clinical IRIS diagnosis of the physician (IRIS_CLINICAL). The primary outcomes were the association between INI and the occurrence of IRIS_FRENCH and IRIS_{FRENCH+CLINICAL} in multivariable logistic regression.

FINDINGS

672 patients with a median CD4⁺ T-cell count of 35 cells per μL were included. Treatment with INI was independently associated with IRIS_FRENCH as well as IRIS_{FRENCH+CLINICAL} (OR 2·43, 95%CI:1·45-4·07, and OR 2·17, 95%CI:1·45-3·25). When investigating INI separately, raltegravir (RAL) remained significantly associated with IRIS_FRENCH (OR 4·04 (95%CI:1·99-8·19) as well as IRIS_{FRENCH+CLINICAL} (OR 3·07, 95%CI:1·66-5·69), while dolutegravir (DTG) became associated with IRIS_{FRENCH+CLINICAL} after it replaced RAL as preferred INI in the cohort after 2015 (OR 4·08, 95%CI:0·99-16·82, p=0·052). Too few patients used elvitegravir to draw meaningful conclusions. Steroid initiation for IRIS was more likely in those who initiated INI versus in those who did not, but no increased hospital (re)admission or mortality rates were observed.

INTERPRETATION

In HIV late presenters from a resource rich setting, INI based treatment initiation increased the risk of IRIS. This was observed for RAL and DTG when being initiated as preferential INI in the presence of specific AIDS-conditions, indicative of channeling bias. Although we controlled for all relevant measured confounders, we cannot exclude that the observed association is partially explained by residual confounding. INI use was not associated with mortality nor hospitalization. Therefore, our observation is no reason to avoid INI in late presenters.

FUNDING

The ATHENA database is maintained by Stichting HIV Monitoring and supported by a grant from the Dutch Ministry of Health, Welfare and Sport through the Centre for Infectious Disease Control of the National Institute for Public Health and the Environment.

Emergence of Polyfunctional Cytotoxic CD4+ T Cells in Mycobacterium avium Immune Reconstitution Inflammatory Syndrome in Human Immunodeficiency Virus-Infected Patients

Background

Immune reconstitution inflammatory syndrome (IRIS) is an aberrant inflammatory response in individuals with advanced human immunodeficiency virus (HIV) infection, after antiretroviral therapy (ART) initiation. The pathogenesis of Mycobacterium avium complex (MAC)-associated IRIS has not been fully elucidated.

Methods

We investigated monocyte and CD4+ T-cell responses in vitro, tumor necrosis factor (TNF) expression in tissues, and plasma cytokines and inflammatory markers, in 13 HIV-infected patients with MAC-IRIS and 14 HIV-uninfected patients with pulmonary MAC infection.

Results

Prior to ART, HIV-infected compared with HIV-uninfected patients, had reduced TNF+ monocytes (P = .013), although similar cytokine (interferon gamma [IFN-γ], TNF, interleukin 2 [IL-2], and interleukin 17 [IL-17])-expressing CD4+ T cells. During IRIS, monocyte cytokine production was restored. IFN-γ+ (P = .027), TNF+ (P = .004), and polyfunctional CD4+ T cells (P = 0.03) also increased. These effectors were T-betlow, and some expressed markers of degranulation and cytotoxic potential. Blockade of cytotoxic T-lymphocyte associated protein 4 and lymphocyte activation gene-3 further increased CD4+ T-cell cytokine production. Tissue immunofluorescence showed higher proportions of CD4+ and CD68+ (monocyte/macrophage) cells expressed TNF during IRIS compared with HIV-uninfected patients. Plasma IFN-γ (P = .048), C-reactive protein (P = .008), and myeloperoxidase (P < .001) levels also increased, whereas interleukin 10 decreased (P = .008) during IRIS.

Conclusions

Advanced HIV infection was associated with impaired MAC responses. Restoration of monocyte responses and expansion of polyfunctional MAC-specific T-betlow CD4+ T cells with cytotoxic potential after ART initiation may overwhelm existing regulatory and inhibitory mechanisms, leading to MAC-IRIS.

Neurotuberculosis: Control of Steroid-Refractory Paradoxical Inflammatory Reaction With Ruxolitinib

Paradoxical inflammatory reactions associated with treatment of neurotuberculosis can lead to severe morbidity and mortality and may not be controlled by steroids alone. We report the use of the Janus kinase inhibitor ruxolitinib to treat a steroid-refractory neurotuberculosis paradoxical reaction.

Two cases of immune reconstitution inflammatory syndrome in HIV patients treated with thalidomide

Immune reconstitution inflammatory syndrome (IRIS) is a clinical manifestation that accompanies paradoxical deterioration of symptoms in human immunodeficiency virus (HIV)-infected patients after commencement of antiretroviral treatment. This disease is caused by immune dysregulation, resulting in a cytokine storm and limited effector T-cell function. IRIS treatment involves supportive care and corticosteroid therapy to regulate the immune response. However, prolonged steroid therapy may increase the risk of opportunistic infections. Previous studies have highlighted the use of thalidomide to shorten the duration of steroid use. Herein, we report two cases of IRIS in HIV-infected patients whose symptoms were successfully controlled with thalidomide therapy. Both patients had opportunistic infections involving the central nervous system; one patient had cryptococcal meningitis and the other had progressive multifocal leukoencephalopathy.

HIV-Associated Cryptococcal Immune Reconstitution Inflammatory Syndrome Is Associated with Aberrant T Cell Function and Increased Cytokine Responses

Cryptococcal meningitis remains a significant opportunistic infection among HIV-infected patients, contributing 15-20% of HIV-related mortality. A complication of initiating antiretroviral therapy (ART) following opportunistic infection is immune reconstitution inflammatory syndrome (IRIS). IRIS afflicts 10-30% of HIV-infected patients with cryptococcal meningitis (CM), but its immunopathogenesis is poorly understood. We compared circulating T cell memory subsets and cytokine responses among 17 HIV-infected Ugandans with CM: 11 with and 6 without CM-IRIS. At meningitis diagnosis, stimulation with cryptococcal capsule component, glucuronoxylomannan (GXM) elicited consistently lower frequencies of CD4⁺ and CD8⁺ T cell memory subsets expressing intracellular cytokines (IL-2, IFN-γ, and IL-17) among subjects who subsequently developed CM-IRIS. After ART initiation, T cells evolved to show a decreased CD8⁺ central memory phenotype. At the onset of CM-IRIS, stimulation more frequently generated polyfunctional IL-2⁺/IL-17⁺ CD4⁺ T cells in patients with CM-IRIS. Moreover, CD8⁺ central and effector memory T cells from CM-IRIS subjects also demonstrated more robust IL-2 responses to antigenic stimulation vs. controls. Thus, ART during CM elicits distinct differences in T cell cytokine production in response to cryptococcal antigens both prior to and during the development of IRIS, suggesting an immunologic foundation for the development of this morbid complication of CM infection.

Differential Pathogen-Specific Immune Reconstitution in Antiretroviral Therapy-Treated Human Immunodeficiency Virus-Infected Children

BACKGROUND

Susceptibility to coinfections in human immunodeficiency virus (HIV)-infected patients remains increased despite antiretroviral therapy (ART). To elucidate mechanisms involved in immune reconstitution, we studied immune activation, immune exhaustion, and HIV- and copathogen-specific T-cell responses in children before and after ART.

METHODS

We prospectively enrolled 25 HIV-infected children to study HIV-, cytomegalovirus (CMV)-, and tuberculosis (TB)-specific T-cell responses before and 1 year after initiation of ART using intracellular cytokine (interleukin-2, interferon-γ, tumor necrosis factor-α) staining assays after in vitro stimulation. We further measured expression of activation, immune exhaustion, and memory phenotype markers and studied proliferative responses after antigen stimulation.

RESULTS

We observed differential, pathogen-specific changes after 1 year of ART in cytokine profiles of CD4 T-cell responses that were associated with shifts in memory phenotype and decreased programmed cell death 1 (PD-1) expression. The proliferative capacity of HIV- and PPD-specific responses increased after 1 year of ART. Of note, the recovery of CMV- and TB-specific responses was correlated with a decrease in PD-1 expression (r = 0.83, P = .008 and r = 0.81, P = .0007, respectively).

CONCLUSIONS

Reconstitution of immune responses on ART is associated with alterations in T-cell phenotype, function, and PD-1 expression that are distinct for HIV, TB, and CMV. The PD-1 pathway represents a potential target for immunotherapy in HIV-infected patients on ART with insufficient immune reconstitution.

CCR4-dependent reduction in the number and suppressor function of CD4+Foxp3+ cells augments IFN-γ-mediated pulmonary inflammation and aggravates tuberculosis pathogenesis

Chronic pulmonary inflammation marked predominantly by CD4⁺IFN-γ⁺ cells is the hallmark of tuberculosis pathogenesis in immunocompetent adults, who are substantially affected by this disease. Moreover, CD4⁺Foxp3⁺ cell-mediated suppression contributes to infection susceptibility. We addressed the role of CD4⁺Foxp3⁺ cells in tuberculosis pathogenesis, because this aspect has not been addressed during chronic infection. We targeted CCR4, which induces the influx of CD4⁺Foxp3⁺ cells into the lungs. CCR4^−/− mice exhibited a lower frequency of CD4⁺Foxp3⁺ cells at 15, 30, and 70 days of infection than their wild-type counterparts. However, only at 70 days of infection was an exacerbated IFN-γ-mediated immune response associated with apparent tuberculosis pathogenesis and susceptibility. In addition, CCR4^−/− mice exhibited a decrease in the suppressor function of CD4⁺Foxp3⁺ cells. Adoptive transfer of Foxp3⁺ cells into infected CCR4^−/− mice restored pulmonary inflammation and bacterial load to levels observed in wild-type mice. Our findings suggest that CD4⁺Foxp3⁺ cells play a time-dependent role in tuberculosis and highlight that CCR4 plays a critical role in the balance of IFN-γ-mediated inflammation by regulating the influx and function of CD4⁺Foxp3⁺ cells. Our findings are translationally relevant, as CD4⁺Foxp3⁺ cells or CCR4 could be a target for immunotherapy, considering the heterogeneity of tuberculosis in immunocompetent adults.

Human Immunodeficiency Virus in the Brain-Culprit or Facilitator?

Introduction:

Human immunodeficiency virus (HIV) enters the brain early, where it can persist, evolve, and become compartmentalized. Central nervous system (CNS) disease can be attributed to HIV alone or to the complex interplay between the virus and other neurotropic pathogens.

Aim:

The current review aims to describe the direct impact of HIV on the brain as well as its relationship with other pathogens from a practitioner’s perspective, to provide a general clinical overview, brief workup, and, whenever possible, treatment guidance.

Methods:

A review of PubMed was conducted to identify studies on neuropathogenesis of HIV in relation to host responses. Furthermore, the interaction between the CNS pathogens and the host damage responses were revised in the setting of advanced and also well-controlled HIV infection.

Results:

Similar to other pathogens, HIV leads to CNS immune activation, inflammation, and viral persistence. Therefore, almost half of the infected individuals present with neurocognitive disorders, albeit mild. Compartmentalized HIV in the CNS can be responsible in a minority of cases for the dramatic presentation of symptomatic HIV escape. Disruption of the immune system secondary to HIV may reactivate latent infections or allow new pathogens to enter the CNS. Opportunistic infections with an inflammatory component are associated with elevated HIV loads in the cerebrospinal fluid and also with greater cognitive impairment. The inflammatory immune reconstitution syndrome associated with CNS opportunistic infections can be a life-threatening condition, which needs to be recognized and managed by efficiently controlling the pathogen burden and timely balanced combination antiretroviral therapy. Latent neurotropic pathogens can reactivate in the brain and mimic HIV-associated severe neurological diseases or contribute to neurocognitive impairment in the setting of stable HIV infection.

Conclusions:

As HIV can be responsible for considerable brain damage directly or by facilitating other pathogens, more effort is needed to recognize and manage HIV-associated CNS disorders and to eventually target HIV eradication from the brain.

IFNγ-producing CD4+ T lymphocytes: the double-edged swords in tuberculosis

IFNγ-producing CD4+ T cells (IFNγ+CD4+ T cells) are the key orchestrators of protective immunity against Mycobacterium tuberculosis (Mtb). Primarily, these cells act by enabling Mtb-infected macrophages to enforce phagosome-lysosome fusion, produce reactive nitrogen intermediates (RNIs), and activate autophagy pathways. However, TB is a heterogeneous disease and a host of clinical and experimental findings has also implicated IFNγ+CD4+ T cells in TB pathogenesis. High frequency of IFNγ+CD4+ T cells is the most invariable feature of the active disease. Active TB patients mount a heightened IFNγ+CD4+ T cell response to mycobacterial antigens and demonstrate an IFNγ-inducible transcriptomic signature. IFNγ+CD4+ T cells have also been shown to mediate TB-associated immune reconstitution inflammatory syndrome (TB-IRIS) observed in a subset of antiretroviral therapy (ART)-treated HIV- and Mtb-coinfected people. The pathological face of IFNγ+CD4+ T cells during mycobacterial infection is further uncovered by studies in the animal model of TB-IRIS and in Mtb-infected PD-1-/- mice. This manuscript encompasses the evidence supporting the dual role of IFNγ+CD4+ T cells during Mtb infection and sheds light on immune mechanisms involved in protection versus pathogenesis.

Monocyte Phenotype and IFN-γ-Inducible Cytokine Responses Are Associated with Cryptococcal Immune Reconstitution Inflammatory Syndrome

A third of adults with AIDS and cryptococcal meningitis (CM) develop immune reconstitution inflammatory syndrome (IRIS) after initiating antiretroviral therapy (ART), which is thought to result from exaggerated inflammatory antigen-specific T cell responses. The contribution of monocytes to the immunopathogenesis of cryptococcal IRIS remains unclear. We compared monocyte subset frequencies and immune responses in HIV-infected Ugandans at time of CM diagnosis (IRIS-Baseline) for those who later developed CM-IRIS, controls who did not develop CM-IRIS (Control-Baseline) at CM-IRIS (IRIS-Event), and for controls at a time point matched for ART duration (Control-Event) to understand the association of monocyte distribution and immune responses with cryptococcal IRIS. At baseline, stimulation with IFN-γ ex vivo induced a higher frequency of TNF-α- and IL-6-producing monocytes among those who later developed IRIS. Among participants who developed IRIS, ex vivo IFN-γ stimulation induced higher frequencies of activated monocytes, IL-6⁺, TNF-α⁺ classical, and IL-6⁺ intermediate monocytes compared with controls. In conclusion, we have demonstrated that monocyte subset phenotype and cytokine responses prior to ART are associated with and may be predictive of CM-IRIS. Larger studies to further delineate innate immunological responses and the efficacy of immunomodulatory therapies during cryptococcal IRIS are warranted.

Single-cell profiling of lineage determining transcription factors in antigen-specific CD4+ T cells reveals unexpected complexity in recall responses during immune reconstitution

Recent studies of protein and gene expression at the single-cell level have revealed that the memory T-cell compartment is more heterogeneous than previously acknowledged. Identifying different T helper subsets involved in memory responses at the single-cell level is thus necessary to understand the level of heterogeneity within this population. Antigen-specific CD4⁺ T cells were measured using the CD25/OX40 assay together with a qualitative multiplex single-cell RT-PCR assay. Transcription profiles and subset proportions within the antigen-specific CD4⁺ T-cell population were dissected. Cytomegalovirus (CMV)-specific CD4⁺ T-cell responses skewed toward a Th1 response, whereas Tetanus toxoid responses skewed toward a Th2 type response. Fluctuations in CD4⁺ T-cell subsets were observed within the HIV-Gag-specific response during ongoing antiretroviral therapy. Strong effector responses (Th1) were observed in early treatment, however with ongoing therapy this effector response significantly decreased in combination with an increase in Tregs and circulating Tfh-like BCL-6⁺ memory cells. The apparent increase in Tcm in peripheral blood after a several weeks of antiretroviral therapy may be due to Tfh-like cell egress from germinal centers into the periphery.

Confusion in the Study of Immune Reconstitution Inflammatory Syndrome

As a consequence of late presentation for HIV care, a significant proportion of individuals develop immune reconstitution inflammatory syndrome (IRIS) soon after initiation of antiretroviral therapy. Incidence, predictors, and models of pathogenesis of IRIS vary in the literature. Here we discuss factors that may contribute to this lack of consensus. We propose that different pathogens drive different types of IRIS and suggest that these clinical conditions should be studied individually and not grouped under the general heading of "IRIS."

Hospital days attributable to immune reconstitution inflammatory syndrome in persons living with HIV before and after the 2012 DHHS HIV guidelines

Background

Immune reconstitution inflammatory syndrome (IRIS) can manifest with initiation or reintroduction of antiretroviral therapy (ART) in persons living with HIV (PLWH). In 2012, updated United States treatment guidelines recommended initiation of ART for all PLWH regardless of CD4 count. The objectives of this study were to quantify hospital usage attributable to IRIS and assess the reasons for hospitalization in PLWH before and after the guideline update.

Methods

Subjects were PLWH between 18–89 years of age who were hospitalized between November 1, 2009 and July 31, 2014. Equivalent time periods before and after updated treatment guidelines were considered, and designated as Time Period 1 and Time Period 2, respectively. IRIS-attributable hospitalizations were identified by ICD9 codes and electronic medical record searches with subsequent review and confirmation. For hospitalizations that were not confirmed as being IRIS-attributable, primary discharge diagnoses were reviewed.

Results

A total of 278 PLWH were hospitalized 521 times throughout the study period. Time Period 1 had 9 PLWH with 12 IRIS-attributable hospitalizations while Time Period 2 had 6 PLWH with 9 IRIS-attributable hospitalizations. A larger proportion of IRIS-attributable hospital days was observed in Time Period 1 compared to Time Period 2 (7.5 vs 4.2%; p < 0.001). Median length of stay for IRIS-attributable hospitalizations was longer than for other diagnoses, particularly during Time Period 1 (12.0 vs 4.0; p = 0.05). The most common causes for hospitalizations in PLWH were non AIDS-defining infection, AIDS-defining malignancy, and gastrointestinal. PLWH who had HIV viral suppression (<200 copies/mL) accounted for 34 and 24% of hospitalizations in Time Periods 1 and 2 respectively.

Conclusions

Hospitalizations for PLWH continue at high rates and IRIS is a significant contributing factor. In our single-center study, there was a lower number of IRIS-attributable hospitalizations and IRIS-attributable hospital days in Time Period 2 compared with Time Period 1. The hospital burden of IRIS may decrease over time as more PLWH are started on ART earlier in the course of infection. This study highlights the continued importance of early diagnosis and linkage to care of those infected with HIV, so that morbidity and costs associated with IRIS continue to decline.

Toxoplasmosis-associated IRIS involving the CNS: a case report with longitudinal analysis of T cell subsets

Background

HIV-infected patients may present an unforeseen clinical worsening after initiating antiretroviral therapy known as immune reconstitution inflammatory syndrome (IRIS). This syndrome is characterized by a heightened inflammatory response toward infectious or non-infectious triggers, and it may affect different organs. Diagnosis of IRIS involving the central nervous system (CNS-IRIS) is challenging due to heterogeneous manifestations, absence of biomarkers to identify this condition, risk of long-term sequelae and high mortality. Hence, a deeper knowledge of CNS-IRIS pathogenesis is needed.

Case presentation

A 37-year-old man was diagnosed with AIDS and cerebral toxoplasmosis. Anti-toxoplasma treatment was initiated immediately, followed by active antiretroviral therapy (HAART) 1 month later. At 2 months of HAART, he presented with progressive hyposensitivity of the right lower limb associated with brain and dorsal spinal cord lesions, compatible with paradoxical toxoplasmosis-associated CNS-IRIS, a condition with very few reported cases. A stereotactic biopsy was planned but was postponed based on its inherent risks. Patient showed clinical improvement with no requirement of corticosteroid therapy. Routine laboratorial analysis was complemented with longitudinal evaluation of blood T cell subsets at 0, 1, 2, 3 and 6 months upon HAART initiation. A control group composed by 9 HIV-infected patients from the same hospital but with no IRIS was analysed for comparison. The CNS-IRIS patient showed lower percentage of memory CD4⁺ T cells and higher percentage of activated CD4⁺ T cells at HAART initiation. The percentage of memory CD4⁺ T cells drastically increased at 1 month after HAART initiation and became higher in comparison to the control group until clinical recovery onset; the percentage of memory CD8⁺ T cells was consistently lower throughout follow-up. Interestingly, the percentage of regulatory T cells (Treg) on the CNS-IRIS patient reached a minimum around 1 month before symptoms onset.

Conclusion

Although both stereotactic biopsies and steroid therapy might be of use in CNS-IRIS cases and should be considered for these patients, they might be unnecessary to achieve clinical improvement as shown in this case. Immunological characterization of more CNS-IRIS cases is essential to shed some light on the pathogenesis of this condition.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2159-x) contains supplementary material, which is available to authorized users.

Immune reconstitution inflammatory syndrome in HIV infection: taking the bad with the good

In this review, we will describe the immunopathogies of immune reconstitution inflammatory syndrome, IRIS. IRIS occurs in a small subset of HIV patient, initiating combination antiretroviral therapy (ART), where immune reconstitution becomes dysregulated, resulting in an overly robust antigen-specific inflammatory reaction. We will discuss IRIS in terms of the associated coinfections: mycobacteria, cryptococci, and viruses.

HIV infection and immune activation: the role of coinfections

PURPOSE OF REVIEW

This article explores new data from recent studies addressing the role of coinfections in immune activation in HIV-1-infected patients, with a focus on immune reconstitution inflammatory syndrome (IRIS), an aberrant inflammatory response occurring shortly after antiretroviral therapy (ART) initiation.

RECENT FINDINGS

Chronic HIV infection is associated with several coinfections that contribute to immune activation in various settings including early after ART initiation in the most noticeable form of IRIS and also in chronic-treated infection, with chronic viral infections like cytomegalovirus and hepatitis C or hepatitis B virus contributing to immune activation and also morbidity and mortality. Expanding on older studies, the role of T cells in IRIS has been further elucidated with evidence of more pronounced effector activity in patients with IRIS that may be leading to excessive tissue disorder. Newer studies are also continuing to shed light on the role of myeloid cells as well as the contribution of antigen load in IRIS. In addition, preliminary data are beginning to suggest a possible role of inflammasome formation in IRIS. In cryptococcal IRIS, the role of activated immune cells (T cell and myeloid) and biomarkers were evaluated in more detail at the site of infection (cerebrospinal fluid). Finally, important differences of patients developing IRIS versus those who die from tuberculosis despite ART initiation were reported, a distinction that may have important implications for participant selection in studies aiming to prevent IRIS with immunosuppressive agents.

SUMMARY

Better understanding of the role of opportunistic infections at ART initiation and IRIS pathogenesis will assist in improved strategies for prevention and treatment. The long-term consequences of IRIS remain unclear. Chronic viral coinfections with herpesviruses and hepatitis C virus are important factors in persistent immune activation in chronic-treated HIV.

Reconstitution of Peripheral T Cells by Tissue-Derived CCR4+ Central Memory Cells Following HIV-1 Antiretroviral Therapy

Background:

Highly active antiretroviral therapy induces clinical benefits to HIV-1 infected individuals, which can be striking in those with progressive disease. Improved survival and decreased incidence of opportunistic infections go hand in hand with a suppression of the plasma viral load, an increase in peripheral CD4⁺ T-cell counts, as well as a reduction in the activation status of both CD4⁺ and CD8⁺ T cells.

Methods:

We investigated T-cell dynamics during ART by polychromatic flow cytometry in total as well as in HIV-1-specific CD4⁺ and CD8⁺ T cells in patients with advanced disease. We also measured gene expression by single cell transcriptomics to assess functional state.

Results:

The cytokine pattern of HIV-specific CD8⁺ T cells was not altered after ART, though their magnitude decreased significantly as the plasma viral load was suppressed to undetectable levels. Importantly, while CD4⁺ T cell numbers increased substantially during the first year, the population did not normalize: the increases were largely due to expansion of mucosal-derived CCR4⁺ CD4⁺ T_CM; transcriptomic analysis revealed that these are not classical Th₂-type cells.

Conclusion:

The apparent long-term normalization of CD4⁺ T-cell numbers following ART does not comprise a normal balance of functionally distinct cells, but results in a dramatic Th₂ shift of the reconstituting immune system.

Adult pulmonary tuberculosis as a pathological manifestation of hyperactive antimycobacterial immune response

The intricate relationship between tuberculosis (TB) and immune system remains poorly understood. It is generally believed that weakening of the immune response against Mycobacterium tuberculosis leads to reactivation of latent infection into the active pulmonary disease. However, heterogeneous nature of TB and failure of rationally designed vaccines in clinical trials raises serious questions against the simplistic view of TB as an outcome of weakened immunity. In the wake of accumulating human TB data, it is argued here that a hyperactive antimycobacterial immune response is to blame for the pathogenesis of pulmonary TB in immunocompetent adults. Direct and indirect evidence supporting this notion is presented in this article. Revisiting the role of immune system in TB pathogenesis will pave the way for effective anti-TB vaccines.

Paradoxical reactions and immune reconstitution inflammatory syndrome in tuberculosis

The coalescence of the HIV-1 and tuberculosis (TB) epidemics in Sub-Saharan Africa has had a significant and negative impact on global health. The availability of effective antimicrobial treatment for both HIV-1 (in the form of highly active antiretroviral therapy (HAART)) and TB (with antimycobacterial agents) has the potential to mitigate the associated morbidity and mortality. However, the use of both HAART and antimycobacterial therapy is associated with the development of inflammatory paradoxical syndromes after commencement of therapy. These include paradoxical reactions (PR) and immune reconstitution inflammatory syndromes (IRIS), conditions that complicate mycobacterial disease in HIV seronegative and seropositive individuals. Here, we discuss case definitions for PR and IRIS, and explore how advances in identifying the risk factors and immunopathogenesis of these conditions informs our understanding of their shared underlying pathogenesis. We propose that both PR and IRIS are characterized by the triggering of exaggerated inflammation in a setting of immunocompromise and antigen loading, via the reversal of immunosuppression by HAART and/or antimycobacterials. Further understanding of the molecular basis of this pathogenesis may pave the way for effective immunotherapies for the treatment of PR and IRIS.

The immunopathogenesis of cryptococcal immune reconstitution inflammatory syndrome: understanding a conundrum

PURPOSE OF REVIEW

Cryptococcal meningitis causes significant mortality among HIV-infected patients, despite antifungal therapy and use of antiretroviral therapy (ART). In patients with cryptococcal meningitis, ART is often complicated by immune reconstitution inflammatory syndrome (IRIS), manifesting as unmasking of previously unrecognized subclinical infection (unmasking CM-IRIS) or paradoxical worsening of symptoms in the central nervous system after prior improvement with antifungal therapy (paradoxical CM-IRIS). We review our current understanding of the pathogenesis of this phenomenon, focusing on unifying innate and adaptive immune mechanisms leading to the development of this often fatal syndrome.

RECENT FINDINGS

We propose that HIV-associated CD4 T-cell depletion, chemokine-driven trafficking of monocytes into cerebrospinal fluid in response to cryptococcal meningitis, and poor localized innate cytokine responses lead to inadequate cryptococcal killing and clearance of the fungus. Subsequent ART-associated recovery of T-cell signaling and restored cytokine responses, characterized by IFN-γ production, triggers an inflammatory response. The inflammatory response triggered by ART is dysregulated because of impaired homeostatic and regulatory mechanisms, culminating in the development of CM-IRIS.

SUMMARY

Despite our incomplete understanding of the immunopathogenesis of CM-IRIS, emerging data exploring innate and adaptive immune responses could be exploited to predict, prevent and manage CM-IRIS and associated morbid consequences.

A Paradoxical Treatment for a Paradoxical Condition: Infliximab Use in Three Cases of Mycobacterial IRIS

The management of corticosteroid refractory immune reconstitution inflammatory syndrome (IRIS) is currently unclear. Infliximab administration was associated with clinical improvement without significant adverse events in 3 patients with mycobacterial IRIS. Immunologic and virologic responses to antiretroviral therapy were unaffected. Tumor necrosis factor blockade may be beneficial for IRIS and warrants further study in clinical trials.

Persistent high mortality in advanced HIV/TB despite appropriate antiretroviral and antitubercular therapy: an emerging challenge

Approximately 1.1 million, or 13 %, of all TB cases in 2013 were coinfected with HIV, and in some African countries, such as Botswana and Swaziland, 60-80 % of TB cases are coinfected with HIV. Effective therapies for both HIV and TB exist, yet patients presenting with TB and advanced HIV still experience high rates of morbidity and mortality despite initiation of both antitubercular and antiretroviral therapy (ART). Previous reviews and research have focused largely on TB-associated immune reconstitution inflammatory syndrome (TB-IRIS) as a type of complicated outcome on ART in advanced HIV/TB, but recent data indicate that immunologic failure despite suppressive ART is associated with early mortality. In this review, we examine recent findings regarding early mortality in HIV/TB and emerging concepts in the pathophysiology of TB-IRIS, in order to provide an integrated view of factors determining outcomes in coinfected people as well as highlight key needs for future research and therapeutic development.

PD-1 Expression and Cytokine Secretion Profiles of Mycobacterium tuberculosis-Specific CD4+ T-Cell Subsets; Potential Correlates of Containment in HIV-TB Co-Infection

HIV co-infection is an important risk factor for tuberculosis (TB) providing a powerful model in which to dissect out defective, protective and dysfunctional Mycobacterium tuberculosis (MTB)-specific immune responses. To identify the changes induced by HIV co-infection we compared MTB-specific CD4+ responses in subjects with active TB and latent TB infection (LTBI), with and without HIV co-infection. CD4+ T-cell subsets producing interferon-gamma (IFN-γ), interleukin-2 (IL-2) and tumour necrosis factor-alpha (TNF-α) and expressing CD279 (PD-1) were measured using polychromatic flow-cytometry. HIV-TB co-infection was consistently and independently associated with a reduced frequency of CD4+ IFN-γ and IL-2-dual secreting T-cells and the proportion correlated inversely with HIV viral load (VL). The impact of HIV co-infection on this key MTB-specific T-cell subset identifies them as a potential correlate of mycobacterial immune containment. The percentage of MTB-specific IFN-γ-secreting T-cell subsets that expressed PD-1 was increased in active TB with HIV co-infection and correlated with VL. This identifies a novel correlate of dysregulated immunity to MTB, which may in part explain the paucity of inflammatory response in the face of mycobacterial dissemination that characterizes active TB with HIV co-infection.

Severe Paradoxical Reaction During Treatment of Disseminated Tuberculosis in a Patient With Neutralizing Anti-IFNγ Autoantibodies

Interferon-gamma (IFNγ) neutralizing autoantibodies are associated with disseminated nontuberculous mycobacterial infections. We report a previously healthy Thai woman with disseminated tuberculosis and high-titer IFNγ-neutralizing autoantibodies, who developed a severe inflammatory reaction during anti-tuberculosis treatment. IFNγ contributes to host control of tuberculosis but appears inessential for tuberculosis paradoxical reactions.

Robust Reconstitution of Tuberculosis-Specific Polyfunctional CD4+ T-Cell Responses and Rising Systemic Interleukin 6 in Paradoxical Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome

BACKGROUND

The immunopathogenesis of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) remains unclear. We determined the association between pathogen-specific T-cell responses and development of paradoxical TB-IRIS on antiretroviral therapy (ART).

METHODS

This study was nested within a prospective cohort study of HIV-infected patients with active pulmonary tuberculosis and baseline CD4 counts ≤125 cells/µL initiating ART. T-cell immune activation (CD38, HLA-DR, and PD-1 expression), phenotype, and polyfunctional pathogen-specific cellular immune responses prior to and 4 weeks after ART initiation were determined by flow cytometry. Patients with TB-IRIS were compared to non-IRIS controls using χ(2) and rank-sum tests and logistic regression.

RESULTS

TB-IRIS patients and controls had similar CD4 counts, levels of T-cell-associated immune activation, frequencies of T-cell memory subsets, and frequencies of interferon gamma (IFN-γ(+))/interleukin 2 (IL-2(+))/tumor necrosis factor alpha (TNF-α(+)) CD4(+) T-cells prior to ART initiation. After ART initiation, cellular immune activation and T-cell subsets also were similar in TB-IRIS patients and controls. In contrast, TB-IRIS patients had significantly greater early increases in the frequency of tuberculosis-specific polyfunctional IFN-γ(+)/IL-2(+)/TNF-α(+) CD4(+) T-cells on ART (P = .02); each quartile increase in the percentage of these cells was independently associated with a 2.8-fold increased risk of TB-IRIS (95% confidence interval, 1.1 to 7.5-fold). In a secondary analysis, patients with TB-IRIS had rapid, concomitant increases in tuberculosis-specific adaptive immune responses and interleukin 6 (IL-6) levels, whereas controls with similarly rapid increases in cellular immune function had IL-6 levels that tended to decrease on ART.

CONCLUSIONS

Rapid expansion of tuberculosis-specific polyfunctional CD4(+) T-cell responses, likely linked to increases in IL-6, is associated with development of paradoxical TB-IRIS.

To have and have not: dissecting protective and pathologic immune recovery in TB-IRIS

Paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a growing concern for advanced HIV/TB coinfected patients in an era where antiretroviral therapy (ART) is started shortly after TB treatment initiation. This perspective discusses potential mechanisms underlying TB-IRIS, focusing on recent studies that implicate coordinated recovery in adaptive and innate immune responses following ART initiation in TB-IRIS. More broadly, HIV/TB patients are probably a heterogeneous group whose outcomes are determined by the direction in which these immune responses change following ART initiation. Finally, in addition to treatment interventions that are in the pipeline for TB-IRIS, we highlight the need for holistic management of HIV/TB coinfected patients, which go beyond the current definition of TB-IRIS and take into consideration long-term consequences of robust immune recovery on ART.

HIV-1 tuberculosis-associated immune reconstitution inflammatory syndrome

Patients co-infected with HIV-1 and tuberculosis (TB) are at risk of developing TB-associated immune reconstitution inflammatory syndrome (TB-IRIS) following commencement of antiretroviral therapy (ART). TB-IRIS is characterized by transient but severe localized or systemic inflammatory reactions against Mycobacterium tuberculosis antigens. Here, we review the risk factors and clinical management of TB-IRIS, as well as the roles played by different aspects of the immune response in contributing to TB-IRIS pathogenesis.

Towards a scalable HIV cure research agenda: the role of co-infections

The development of a cure is among the foremost contemporary priorities in the field of HIV research. The science that underpins a potential HIV cure should be generalisable to the many millions of persons globally who enter antiretroviral treatment programs with advanced immunosuppression and/or an opportunistic infection. We provide five key suggestions for incorporation into the HIV cure research agenda to maximise the generalisability and applicability of an HIV cure once developed.

Short communication: mucocutaneous leishmaniasis in HIV-related immune reconstitution syndrome

Immune reconstitution inflammatory syndrome (IRIS) is an immuno-pathologic reaction to quiescent opportunistic microbial pathogens upon restoration of underlying immune defects. Here we report a Honduran patient with HIV/AIDS who developed a facial rash worsening on antiretroviral therapy and increasing CD4 count. Culture and PCR analysis from the skin biopsy identified Leishmania panamensis, which was effectively treated with long-term liposomal amphotericin B. This is the first report of mucocutaneous leishmaniasis (MCL)-associated IRIS due to L. panamensis.

Restoration of CD4+ Responses to Copathogens in HIV-Infected Individuals on Antiretroviral Therapy Is Dependent on T Cell Memory Phenotype

Antiretroviral therapy (ART) induces rapid suppression of viral replication and a progressive replenishment of CD4(+) T cells in HIV-infected individuals. However, the effect of ART on restoring pre-existing memory CD4(+) T cells specific for common copathogens is still unclear. To better understand the dynamics of Ag-specific CD4(+) T cells during ART, we assessed the frequency, functional capacity, and memory profile of CD4(+) T cells specific for Mycobacterium tuberculosis and CMV in 15 HIV-infected individuals before and 1 y after ART initiation. After ART initiation, the frequency of M. tuberculosis-specific CD4(+) T cells showed little change, whereas CMV-specific CD4(+) T cells were significantly lower (p = 0.003). There was no difference in the polyfunctional or memory profile of Ag-specific CD4(+) T cells before and after ART. The replenishment of Ag-specific CD4(+) T cells correlated with the memory differentiation profile of these cells prior to ART. Pathogen-specific CD4(+) T cells exhibiting a late differentiated profile (CD45RO(+)CD27(-)) had a lower capacity to replenish (p = 0.019; r = -0.5) compared with cells with an early differentiated profile (CD45RO(+)CD27(+); p = 0.04; r = 0.45). In conclusion, restoration of copathogen-specific memory CD4(+) T cells during treated HIV infection is related to their memory phenotype, in which early differentiated cells (such as most M. tuberculosis-specific cells) have a higher replenishment capacity compared with late differentiated cells (such as most CMV-specific cells). These data identify an important, hitherto unrecognized, factor that may limit restoration of copathogen immunity in HIV-infected individuals on ART.