Immunosenescence and aging in HIV:

T Cell Homeostasis Disturbances in a Cohort of Long-Term Elite Controllers of HIV Infection

Elite controllers (ECs) are people living with HIV (PLWH) able to control HIV replication without antiretroviral therapy and have been proposed as a model of a functional HIV cure. Much evidence suggests that this spontaneous control of HIV has a cost in terms of T cell homeostasis alterations. We performed a deep phenotypic study to obtain insight into T cell homeostasis disturbances in ECs maintaining long-term virologic and immunologic control of HIV (long-term elite controllers; LTECs). Forty-seven PLWH were included: 22 LTECs, 15 non-controllers under successful antiretroviral therapy (onART), and 10 non-controllers not receiving ART (offART). Twenty uninfected participants (UCs) were included as a reference. T cell homeostasis was analyzed by spectral flow cytometry and data were analyzed using dimensionality reduction and clustering using R software v3.3.2. Dimensionality reduction and clustering yielded 57 and 54 different CD4 and CD8 T cell clusters, respectively. The offART group showed the highest perturbation of T cell homeostasis, with 18 CD4 clusters and 15 CD8 clusters significantly different from those of UCs. Most of these alterations were reverted in the onART group. Interestingly, LTECs presented several disturbances of T cell homeostasis with 15 CD4 clusters and 13 CD8 clusters different from UC. Moreover, there was a specific profile of T cell homeostasis alterations associated with LTECs, characterized by increases in clusters of naïve T cells, increases in clusters of non-senescent effector CD8 cells, and increases in clusters of central memory CD4 cells. These results demonstrate that, compared to ART-mediated control of HIV, the spontaneous control of HIV is associated with several disturbances in CD4 and CD8 T cell homeostasis. These alterations could be related to the existence of a potent and efficient virus-specific T cell response, and to the ability to halt disease progression by maintaining an adequate pool of CD4 T cells.

Disparities in multimorbidity and mortality among people living with and without HIV across British Columbia's health regions: a population-based cohort study

OBJECTIVES

Longer survival has increased the likelihood of antiretroviral-treated people living with HIV (PLWH) developing age-associated comorbidities. We compared the burden of multimorbidity and all-cause mortality across HIV status in British Columbia (BC), and assessed the longitudinal effect of multimorbidity on all-cause mortality among PLWH.

METHODS

Antiretroviral-treated PLWH aged ≥19 years and 1:4 age-sex-matched HIV-negative individuals from a population-based cohort were followed for ≥1 year during 2001-2012. Diagnoses of seven age-associated comorbidities were identified from provincial administrative databases and grouped into 0, 1, 2, and ≥3 comorbidities. Multimorbidity prevalence and age-standardized mortality rates (ASMRs) in both populations were stratified by BC's health regions. Marginal structural models were used to estimate the effect of multimorbidity on mortality among PLWH, adjusted for time-varying confounders affected by prior multimorbidity.

RESULTS

Among 8031 PLWH and 32,124 HIV-negative individuals, 25% versus 11% developed multimorbidity, and 23.53 deaths/1000 person-years (95% confidence interval [95% CI]: 22.02-25.13) versus 3.04 (2.81-3.29) were observed, respectively. PLWH in Northern region had the highest ASMR, but those in South Vancouver Island experienced the greatest difference in mortality compared with HIV-negative individuals. Among PLWH, compared with those with zero comorbidities, adjusted hazard ratios for those with 1, 2, and ≥3 comorbidities were 3.36 (95% CI: 2.86-3.95), 6.92 (5.75-8.33), and 12.87 (10.45-15.85), respectively.

CONCLUSION

PLWH across BC's health regions experience excess multimorbidity and associated mortality. We highlight health disparities which are key when planning the distribution of healthcare resources across BC, and provide evidence for improved HIV care models integrating prevention and management of chronic diseases.

96-week results of a dual therapy with darunavir/ritonavir plus rilpivirine once a day vs triple therapy in patients with suppressed viraemia: virological success and non-HIV related morbidity evaluation

Antiretroviral therapies have been tested with the goal of maintaining virological suppression with a particular attention in limiting drug-related toxicity. With this aim we designed the DUAL study: a randomized, open-label, multicenter, 96 weeks-long pilot exploratory study in virologically suppressed HIV-1+ patients with the aim of evaluating the immunovirological success and the impact on non-HIV related morbidity of switching to a dual therapy with darunavir-ritonavir (DRV/r) and rilpivirine (RPV). We recruited patients who received a PI/r-containing HAART for ≥6 months, HIV-RNA < 50 cp/mL for ≥3 months, eGFR > 60 mL/min/1,73m2, without DRV or RPV RAMs. We randomized patients in arm A: RPV + DRV/r QD or arm B: ongoing triple therapy. The primary endpoint has been defined as the percentage of patients with HIV-RNA < 50 cp/mL at week 48 (ITT). VACS index, Framingham CVD risk (FRS) and urinary RBP (uRBP) were calculated. We used Chi-square or Fisher statistics for categorical variables and Mann-Whitney U for continuous ones. Forty-one patients were enrolled (22 in arm A, 14 in arm B, plus 5 screening failures): 30 patients reached 96 weeks: 100% had HIV-RNA < 50 cp/mL in arm A versus 91.7% in arm B. Similar changes were observed in median CD4/mL between baseline and week 96 (+59 versus - 31, p: n.s.). Thirty-one in arm A and 23 in arm B adverse events took place, whereas only 1 was serious (arm A: turbinate hypertrophy, unrelated to HAART). Among the 6 discontinuations (3 in A, 3 in B), only 1 was related to adverse event (arm A: G3 depression, insomnia, weakness). VACS index, median FRS and median uRBP values did not vary from baseline to week 96. At 96-weeks all patients switched to a QD 2-drug regimen based on DRV/r + RPV maintained HIV-RNA suppression, but a single patient who showed a virological failure at week 4. CD4 counts increased overtime without significant differences between the two arms. The novel dual regimen was well tolerated with the same amount of discontinuation as the control arm. VACS index, FRS and uRBP did not differ between arms at week 96.

Fracture-related infections in HIV infected patients: A systematic review and meta-analysis

Aim

To conduct a systematic review and meta-analysis comparing the incidence of fracture-related infections (FRI) following surgical management of closed and open fractures in HIV-positive and HIV-negative patients.

Methods

A systematic literature search was conducted using MEDLINE, ProQuest, Web of Science, The Cochrane Library and Scopus. Our own files and reference lists of identified key articles were also searched. We included studies where the primary outcome was the development of FRI in patients with open and closed fractures.

Results

Eleven studies were included for data synthesis. HIV-positive patients had a non-significant increase in FRI when compared to HIV-negative patients (in open and closed fractures combined). Open fractures treated in the pre-antiretroviral era had a 5.6 times greater risk for developing a FRI. In the post-antiretroviral era (1997 onwards) HIV-positive patients did not have a greater risk of FRI than HIV-negative patients for both open and closed fractures. The small retrospective natures of these studies, together with the heterogeneous outcome definitions used, are limitations to this study.

Conclusion

While there are few large prospective studies, the available data suggests that before the introduction antiretroviral therapy HIV infection was associated with a greater risk of FRI. In the post-antiretroviral era HIV infected patients did not show an increased risk of FRI.

Perspective on potential impact of HIV central nervous system latency on eradication

: Given the challenges of life-long adherence to suppressive HIV antiretroviral therapy (ART) and possibilities of comorbidities, such as HIV association neurocognitive disorder, HIV remission and eradication are desirable goals for people living with HIV. In some individuals, there is evidence that HIV persists and replicates in the CNS, impacting the success of HIV remission interventions. This article addresses the role of HIV CNS latency on HIV eradication, examines the effects of early ART, latency-modifying agents, antibody-based and T-cell enhancing therapies on the CNS as well as ART interruption in remission studies. We propose the integration of CNS monitoring into such studies in order to clarify the short-term and long-term neurological safety of experimental agents and treatment interruption, and to better characterize their effects on HIV CNS persistence.

Stroke and Systemic Thromboembolism Prevention in People Living With Human Immunodeficiency Virus With Atrial Fibrillation: A Review of Its Implications for Clinical Practice

In the last few decades, types of diseases affecting people living with human immunodeficiency virus (PLHIV) have shifted as the population ages, with cardiovascular disease becoming a leading cause of death in this population. Atrial fibrillation (AF) is an increasingly common arrhythmia both in the general population and in PLHIV, with an estimated prevalence of 2% to 3% among PLHIV. Prevention of stroke and systemic thromboembolism (SSE) with antithrombotic therapy is a cornerstone of AF treatment and substantially decreases AF-related morbidity and mortality. Although updated guidelines extensively discuss this issue, they do not address the peculiarities of PLHIV. The role of human immunodeficiency virus (HIV) infection as an independent factor for SSE in individuals with AF and whether the presence of HIV should alter the threshold for SSE thromboprophylaxis are unknown. Nevertheless, a growing body of evidence describes the increasing burden of comorbidities such as hypertension and stroke in PLHIV, which predispose them to AF and SSE. In the absence of HIV-specific AF guidelines, PLHIV with AF should be comprehensively assessed for their risk of SSE and bleeding using commonly available scores despite them having been primarily validated in the non-HIV population. Both vitamin K antagonists and direct oral anticoagulants can be used in PLHIV. Addressing HIV-related comorbidities and potential drug-drug interactions with antiretrovirals is crucial to prevent SSE and reduce adverse reactions of oral anticoagulants. This review summarizes the current guidelines for SSE prevention in patients with AF and describes key considerations for their implementation among PLHIV receiving antiretroviral therapy.

Chronicity, ageing and multimorbidity

Thanks to highly active antiretroviral therapy (HAART), HIV-related mortality has been drastically reduced and HIV infection has become a chronic disease. The HIV-infected population is ageing prematurely. Despite good immunovirological control, HIV causes chronic inflammation and accelerated immunosenes-cence. This clinically manifests as an increased prevalence of age-related comorbidity and frailty occurring earlier than in the general population. The heterogeneity of older HIV-infected adults highlights the rele-vance of identifying those who are at risk of poor health, and frailty may be an effective indicator. The rela-tionship between ageing, HIV infection, antiretroviral treatment, comorbidities and frailty still needs to be clarified. Elderly HIV-infected adults are complex patients who require a specific, global and multidisci-plinary approach.

Patho-immune Mechanisms of Hypertension in HIV: a Systematic and Thematic Review

PURPOSE OF REVIEW

To systematically review recent findings on the role of immune cell activation in the pathogenesis of hypertension in people living with HIV (PLWH) and compare studies from Sub-Saharan Africa with what is reported in the USA and European literature according to guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RECENT FINDINGS

PLWH have an increased risk for development of hypertension and cardiovascular disease. Chronic immune activation contributes to hypertension but the inflammatory milieu that predisposes PLWH to hypertension is poorly understood. We identified 45 relevant studies from 13 unique African countries. The prevalence of hypertension in PLWH on antiretroviral therapy (ART) and the ART-naive PLWH ranged from 6 to 50% and 2 to 41%, respectively. Interleukin (IL)-17A, interferon (IFN)-γ, and higher CD4+ T cell counts were associated with hypertension in ART-treated participants. Targeting adaptive immune activation could provide improved care for hypertensive PLWH. Further research is needed to characterize the inflammatory milieu contributing to hypertension in PLWH especially in African populations where the global burden of HIV is the highest.

Biomarkers of aging in HIV: inflammation and the microbiome

PURPOSE

HIV-infected subjects present increased levels of inflammatory cytokines and T cell activation in the peripheral blood despite suppressive combination antiretroviral therapy which renders them susceptible to premature aging. The purpose of the present work was to review existing evidence on the ways in which the anatomical and microbiological abnormalities of the gastrointestinal tract can represent a major cause of organ disease in HIV infection.

METHODS

We conducted a systematic review of the Pubmed database for articles published from 2014 to 2018. We included studies on inflammatory/activation biomarkers associated with cardiovascular and bone disease, neurocognitive impairment and serious non-AIDS events in HIV-infected subjects. We also included researches which linked peripheral inflammation/activation to the anatomical, immune and microbiological alterations of the gastrointestinal tract.

RESULTS

Recent literature data confirm the association between non-infectious comorbidities and inflammation in HIV infection which may be driven by gastrointestinal tract abnormalities, specifically microbial translocation and dysbiosis. Furthermore, there is mounting evidence on the possible role of metabolic functions of the microbiota in the pathogenesis of premature aging in the HIV-infected population.

CONCLUSIONS

Biomarkers need to be validated for their use in the management of HIV infection. Compounds which counteract microbial translocation, inflammation and dysbiosis have been investigated as alternative therapeutic strategies in viro-suppressed HIV-infected individuals, but appear to have limited efficacy, probably due to the multifactorial pathogenesis of non-infectious comorbidities in this setting.

[HIV infection as a cause of accelerated aging and frailty]

The HIV-infected population is aging due to the success of combination antiretroviral therapy, which prolongs survival, as well as the growing number of newly diagnosed cases in adults 50 years old and over. HIV-infected individuals suffer from an accelerated aging due to the persistent and chronic activation of the immune system that leads to immune exhaustion and accelerated immunosenescence, even when on optimal immuno-virological control treatment. The clinical expression of the immunosenescence state is an increased prevalence of aging-related non-HIV associated comorbidities and a rising prevalence of frailty occurring earlier than in the general population. Thus, HIV-infected patients are biologically older than their chronological age, and they suffer from aging-related problems, such as frailty, which should be assessed.

Y chromosome mosaicism is associated with age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in industrialised countries, and thereby a major individual but also a socio-economic burden. Y chromosome loss in nucleated blood cells has been implicated in age-related diseases such as Alzheimer disease and was shown to be caused by increasing age, smoking and genetic factors. Mosaic loss of Y chromosome (mLOY) in peripheral blood was estimated from normalised dosages of genotyping chip data covering the male-specific region of the Y chromosome. After quality control, we assessed the association of mLOY on AMD risk in 5772 male cases and 6732 male controls. In controls the prevalence of mLOY increased significantly with age, which is consistent with previous reports. Importantly, mLOY was associated with late-stage AMD with genome-wide significance (OR: 1.332 [95% CI: 1.206; 1.472], P = 1.60e-08), independent of age, the AMD genetic risk score and the first two principle components of ancestry. Additionally conditioning on smoking behaviour had no influence on the observed association strength. mLOY was strongest associated in individuals aged between 65 and 75 years. Taken together, mLOY is significantly associated with risk for AMD, independent of known and potential confounding factors.

Distribution of Human Immunodeficiency Virus (HIV) Ribonucleic Acid in Cerebrospinal Fluid and Blood Is Linked to CD4/CD8 Ratio During Acute HIV

Background

Human immunodeficiency virus (HIV) ribonucleic acid (RNA) levels in the plasma and cerebrospinal fluid (CSF) are correlated in chronic HIV infection, but their dynamics have not been characterized during acute infection.

Methods

This study analyzed predictors of CSF HIV RNA and relative degree of CNS viral transmigration expressed as plasma minus CSF HIV log10 RNA (PCratio) during untreated acute HIV infection. Cerebrospinal fluid immune markers were compared between groups with different PCratio.

Results

One hundred seventeen mostly male (97%) participants in the RV254 cohort in Bangkok, Thailand, had a median age of 28 years and an estimated median 18 days duration of infection; 43 (37%) were Fiebig stages I/II. Twenty-seven (23%) had CSF HIV RNA <80 copies/mL. Those with quantifiable levels (n = 90) had median CSF HIV RNA and PCratio of 3.76 and 2.36 log10 copies/mL, respectively. Human immunodeficiency virus RNA peaked at Fiebig III in plasma and Fiebig IV in CSF. In multivariable analyses, plasma HIV RNA and CD4/CD8 ratio independently correlated with CSF HIV RNA (P < .001), whereas CD4/CD8 ratio predicted PCratio (P = .018). Participants with PCratio <1 had higher CSF neopterin, soluble (s)CD163, interleukin-6, and sCD14 levels (all P < .05).

Conclusions

CD4/CD8 ratio independently correlated with CSF HIV RNA and PCratio, suggesting that immune responses modulate central nervous system viral entry at early infection.

Beneficial and Detrimental Effects of Antiretroviral Therapy on HIV-Associated Immunosenescence

Since the introduction of highly active antiretroviral therapy more than 2 decades ago, HIV-related deaths have dramatically decreased and HIV infection has become a chronic disease. Due to the inability of antiretroviral drugs to eradicate the virus, treatment of HIV infection requires a systemic lifelong therapy. However, even when successfully treated, HIV patients still show increased incidence of age-associated co-morbidities compared with uninfected individuals. Virus- induced immunosenescence, a process characterized by a progressive decline of immune system function, contributes to the premature ageing observed in HIV patients. Although antiretroviral therapy has significantly improved both the quality and length of patient lives, the life expectancy of treated patients is still shorter compared with that of uninfected individuals. In particular, while antiretroviral therapy can contrast some features of HIV-associated immunosenescence, several anti-HIV agents may themselves contribute to other aspects of immune ageing. Moreover, older HIV patients tend to have a worse immunological response to the antiviral therapy. In this review we will examine the available evidence on the role of antiretroviral therapy in the control of the main features regulating immunosenescence.

Impact of illicit opioid use on T cell subsets among HIV-infected adults

Objectives

Opioids have immunosuppressive properties, yet opioid effects on T cell abnormalities consistent with the immune risk phenotype among HIV-infected individuals are understudied.

Methods

To assess associations between illicit opioid use and T cell characteristics (CD4/CD8 ratio, memory profiles based on CD45RO and CD28 expression, and senescence based on CD57 expression), we conducted an exploratory cross-sectional analysis of Russia ARCH, a cohort of antiretroviral therapy (ART)-naïve HIV-infected individuals recruited 11/2012 to 10/2014 in St. Petersburg, Russia. The main independent variable was past 30 day illicit opioid use (yes vs. no). Secondary analyses evaluated none (0 days), intermittent (1 to 7 days), and persistent (8 to 30 days) opioid use. Outcomes were determined with flow cytometry. Analyses were conducted using linear regression models.

Results

Among 186 participants, 38% reported any illicit opioid use (18% intermittent and 20% persistent). Any illicit opioid use was not significantly associated with T cell characteristics. Intermittent opioid use appeared to be associated with decreased memory CD8+ T cells proportion (CD45RO+CD45RA- CD8+ T cells: adjusted mean difference [AMD] [95% CI] = -6.15 [-11.50, -0.79], p = 0.02) and borderline significant increased senescent T cells (%CD57+ of total CD28-CD8+ T cells (AMD [95% CI] = 7.70 [-0.06, 15.46], p = 0.05).

Conclusions

Among ART-naïve HIV-infected Russians, any illicit opioid use was not significantly associated with T cell abnormalities although intermittent illicit opioid use may be associated with CD8 T cell abnormalities. Longitudinal studies are warranted to confirm these findings given increased risk of infections and comorbidities seen among HIV-infected individuals with illicit opioid use.

Atorvastatin restricts HIV replication in CD4+ T cells by upregulation of p21

OBJECTIVE

Antigen persistence due to HIV is a major source of inflammation and substantial immune activation, both of which are linked to accelerated aging. This illustrates the need to reduce immune activation in these patients and subsequently decrease the risk of cardiovascular diseases and other non-AIDS-defining comorbidities.

METHODS

CD4 T cells were infected with HIV-1 isolates in the presence or absence of atorvastatin (0.25 to 1 μg/ml) for 24-48 h. Atorvastatin-induced anti-inflammatory functions and anti-viral replication were measured in vitro.

RESULTS

Atorvastatin, a lipid-lowering medication, exerted a broad spectrum of anti-inflammatory functions by reducing T-cell immune activation markers (e.g. CD38, HLA-DR and Ki67), lowering HIV-1 co-receptor CCR-5, and decreasing proliferative capabilities of CD4 T cells in vitro. In contrast, atorvastatin expanded regulatory T cells (Tregs) and upregulated the expression of T-cell immunoglobulin and ITIM domain (TIGIT), which enhanced the suppressive activity of Tregs. Furthermore, atorvastatin upregulated the cyclin-dependent kinase inhibitor p21, which is also known as cip-1 and waf-1, in the CD4 T cells. Upregulation of p21 in CD4 T cells rendered them less susceptible to HIV-1 infection and replication whereas siRNA-mediated p21 depletion and/or p21 selective inhibitor rescued viral replication. Interestingly, atorvastatin reduced HIV infection in both rested and phytohemagglutinin-activated CD4 T cells in vitro. Finally, atorvastatin mediated p21 upregulation occurred via mevalonate pathway, but independent of p53.

CONCLUSION

The results demonstrate a novel mechanism by which atorvastatin induced resistance of CD4 T cells to HIV-1 infection via p21 upregulation and suggest that statins may hold particular promise for some HIV-infected individuals.

Targeting HIV Reservoir in Infected CD4 T Cells by Dual-Affinity Re-targeting Molecules (DARTs) that Bind HIV Envelope and Recruit Cytotoxic T Cells

HIV reservoirs and production of viral antigens are not eliminated in chronically infected participants treated with combination antiretroviral therapy (cART). Novel therapeutic strategies aiming at viral reservoir elimination are needed to address chronic immune dysfunction and non-AIDS morbidities that exist despite effective cART. The HIV envelope protein (Env) is emerging as a highly specific viral target for therapeutic elimination of the persistent HIV-infected reservoirs via antibody-mediated cell killing. Dual-Affinity Re-Targeting (DART) molecules exhibit a distinct mechanism of action via binding the cell surface target antigen and simultaneously engaging CD3 on cytotoxic T lymphocytes (CTLs). We designed and evaluated Env-specific DARTs (HIVxCD3 DARTs) derived from known antibodies recognizing diverse Env epitopes with or without broadly neutralizing activity. HIVxCD3 DARTs derived from PGT121, PGT145, A32, and 7B2, but not VRC01 or 10E8 antibodies, mediated potent CTL-dependent killing of quiescent primary CD4 T cells infected with diverse HIV isolates. Similar killing activity was also observed with DARTs structurally modified for in vivo half-life extension. In an ex vivo model using cells isolated from HIV-infected participants on cART, combinations of the most potent HIVxCD3 DARTs reduced HIV expression both in quiescent and activated peripheral blood mononuclear cell cultures isolated from HIV-infected participants on suppressive cART. Importantly, HIVxCD3 DARTs did not induce cell-to-cell virus spread in resting or activated CD4 T cell cultures. Collectively, these results provide support for further development of HIVxCD3 DARTs as a promising therapeutic strategy for targeting HIV reservoirs.

Current HIV therapies prevent AIDS by dramatically reducing, but not eliminating, HIV infection. A reservoir of HIV-infected cells persists during long-term antiviral therapy, and individuals are at increased risk to develop non-AIDS illnesses, e.g., accelerated heart, bone, or kidney disease. Novel strategies are thus needed to safely kill HIV-infected cells and reduce or eliminate the HIV reservoir. An emerging strategy to kill HIV-infected cells involves antibodies (Abs) that bind the HIV envelope protein (Env). Env can distinguish HIV-infected cells from uninfected cells, and some Env-specific Abs can kill HIV-infected cells by recruiting immune cells, e.g., NK cells and macrophages. Here, we developed a strategy to kill HIV-infected cells that is complementary to Env-specific Abs. We designed and evaluated Dual-Affinity Re-Targeting (DART) molecules that incorporate Env-binding specificities with a CD3-binding specificity to recruit and activate cytotoxic T cells. We report that HIVxCD3 DARTs potently and selectively kill HIV-infected cells. Furthermore, HIV DARTs perturb resting and activated viral reservoirs in cells isolated from individuals on antiviral therapy. This novel strategy may be an important element of future antiviral therapies that target the HIV reservoir.

Management of cardiovascular conditions in a cohort of patients with HIV: experience from a joint HIV/cardiology clinic

The aim of this study was to assess cardiovascular diagnoses and management in a cohort of patients diagnosed with HIV, and the performance of a joint HIV/Cardiology Clinic in a tertiary hospital setting. A retrospective analysis was performed on all patients referred to a joint HIV/Cardiology Clinic at our hospital. Data on 120 patients were collected. In this predominantly male population (male 101 and female 19) coronary artery disease (CAD) was the most common diagnosis (34%, n = 41). Other diseases included hypertension (12.5%, n = 15), cardiomyopathy (12.5%, n = 15) and arrhythmia (6%, n = 8). The majority of remaining cases included non-cardiac chest pain and palpitations. In addition to usual primary and secondary preventive measures for CAD, complex procedures, such as percutaneous coronary intervention, cardiac resynchronisation therapy for left ventricular systolic dysfunction and radiofrequency ablation for arrhythmias, were carried out. Overall cardiovascular mortality among the group was 2.5% (n = 3) over 4 years. The results indicate the efficacy of a specialist joint HIV/Cardiology Clinic in diagnosing and managing various cardiac conditions in a complex cohort of patients with HIV.

New insights into immune reconstitution inflammatory syndrome of the central nervous system

PURPOSE OF REVIEW

To highlight the importance of immune reconstitution inflammatory syndrome affecting the brain in HIV-infected individuals in the absence of opportunistic infections. To describe the varied clinical manifestations, unifying pathophysiological features and discuss the principles of management of this syndrome.

RECENT FINDINGS

Immune reconstitution inflammatory syndrome within the brain is commonly seen in patients with HIV infection upon initiation of antiretroviral drugs. The fulminant forms occur in the face of opportunistic infections or uncontrolled viral replication within the brain. In this case, the enhanced immune response is targeted against the microbial agent, and the brain suffers bystander damage. Treatment requires the combination of the antimicrobial agent, continued antiretrovirals and in some cases corticosteroids. It is increasingly being recognized that despite adequate control of viral replication in the brain, some patients develop a chronic form of T cell encephalitis which appears to be driven by continued production of HIV-Tat protein. In others, the immune response may be targeted against the host antigens in the brain.

SUMMARY

In patients with central nervous system-immune reconstitution inflammatory syndrome, the use of corticosteroids and strategies that prevent T cell migration into the brain may be needed. Extreme caution is necessary if viral eradication strategies are to be employed that involve activation of viral reservoirs, as these patients may be at risk for developing central nervous system-immune reconstitution inflammatory syndrome.

Immunosuppressive Tryptophan Catabolism and Gut Mucosal Dysfunction Following Early HIV Infection

BACKGROUND

Tryptophan (Trp) catabolism into kynurenine (Kyn) contributes to immune dysfunction in chronic human immunodeficiency virus (HIV) infection. To better define the relationship between Trp catabolism, inflammation, gut mucosal dysfunction, and the role of early antiretroviral therapy (ART), we prospectively assessed patients early after they acquired HIV.

METHODS

Forty patients in the early phase of infection were longitudinally followed for 12 months after receiving a diagnosis of HIV infection; 24 were untreated, and 16 were receiving ART. Kyn/Trp ratio, regulatory T-cells (Tregs) frequency, T-cell activation, dendritic cell counts, and plasma levels of gut mucosal dysfunction markers intestinal-type fatty acid-binding protein, soluble suppression of tumorigenicity 2, and lipopolysaccharide were assessed.

RESULTS

Compared with healthy subjects, patients in the early phase of infection presented with elevated Kyn/Trp ratios, which further increased in untreated patients but normalized in ART recipients. Accordingly, in untreated subjects, the elevated Treg frequency observed at baseline continued to increase over time. The highest CD8(+) T-cell activation was observed during the early phase of infection and decreased in untreated patients, whereas activation normalized in ART recipients. The Kyn/Trp ratio was positively associated with CD8(+) T-cell activation and levels of inflammatory cytokines (interleukin 6, interferon γ-inducible protein 10, interleukin 18, and tumor necrosis factor α) and negatively associated with dendritic cell frequencies at baseline and in untreated patients. However, ART did not normalize plasma levels of gut mucosal dysfunction markers.

CONCLUSIONS

Early initiation of ART normalized enhanced Trp catabolism and immune activation but did not improve plasma levels of gut mucosal dysfunction markers.