Beyond IL-17: new cytokines in the pathogenesis of HIV infection

The protective role of tissue-resident interleukin 17A-producing gamma delta T cells in Mycobacterium leprae infection

Mycobacterium leprae is a kind of disease-causing bacteria and results in leprosy in human. Gamma delta (γδ) T cell is a T-cell subset that is presented in both human dermis and epidermis. These cells bridge innate and adaptive immune responses and play critical roles in regulating anti-microbial defense, wound healing, and skin inflammation. Here, we investigated skin resident γδ T cells in patients with leprosy. Our data showed that γδ T cells significantly accumulated in skin lesions of leprosy patients with tuberculoid (TT) form. IL-23 can predominantly stimulate dermal γδ T cells to produce interleukin 17 (IL-17), a cytokine which may lead to disease protection. These γδ T cells expressed a specific set of surface molecules, and majority of these cells were Vδ1+. Also, IL-23 can stimulate the expansion of dermal γδ T cells expansion. Moreover, our results revealed that the transcription factor RORγt was responsible for IL-17A expression in leprosy lesion. Therefore, these data indicated that IL-23-responsive dermal γδ T cells were the major resource of IL-17A production in the skin and could be a potential target in the treatment of leprosy.

IL6 and FAS/FASL gene polymorphisms may be associated with disease progression in HIV-1-positive ethnically mixed patients

The progression of AIDS depends on the complex host and virus interactions. The most important disease progression hallmarks are immune activation and apoptosis. In this study, we address the prevalence of polymorphisms related to proinflammatory and apoptotic genes, such as IFNG (+874T/A), TNF (308G/A), IL6 (-174G/C), IL8 (-251A/T), FAS (-670A/G), and FASL (-124A/G) in 160 ethnically mixed HIV-1-infected patients from multicentre cohorts with different clinical outcomes (13 elite controllers [EC], 66 slow long-term non-progressors [LTNPs], and 81 progressors [P]). The genotyping was accomplished by TaqMan-qPCR. Among all the polymorphisms analyzed in the cytokines, the IL6 -174G/C polymorphism showed a higher frequency of GG genotype in the LTNP and LTNP+EC groups as compared to the P group. Moreover, there was a significantly higher frequency of the G allele in the LTNP and LTNP+EC groups as compared to the P group. On the other hand, the levels of CD4⁺ T lymphocytes were higher among individuals showing the AA and AG genotypes for the FASL -124A/G polymorphism as compared to the GG genotype. Furthermore, the AG and AA genotypes were more frequent, as compared to the GG genotype, in individuals showing a lower viral load. In contrast, for the FAS -670A/G polymorphism, a significantly higher viral load was observed in individuals with the AG genotype as compared to the GG genotype. In conclusion, we found three genetic allelic variants of the IL6 -174G/C, FASL -124A/G, and FAS -670A/G polymorphisms that were related to disease progression and immunological and virological markers in cohorts of HIV-1-positive ethnically mixed patients.

γδ T cells are associated with inflammation and immunopathogenesis of leprosy reactions

BACKGROUND

Leprosy reactions appear episodically in leprosy patients, which lead to high inflammation, morbidity and peripheral nerve damage. The role of Th17 cell has been well studied in leprosy reactions but the role of γδ or unconventional T cells which is an other major source of IL-17 in many diseases, not studied in leprosy reactional episodes.

OBJECTIVE

The aim of the present study to elucidate the role of γδ T cells in leprosy reactions.

METHODOLOGY

A total of 40 untreated non-reaction and reactions patients were recruited. PBMCs were isolated and stimulated with M. leprae sonicated antigen (MLSA) for 48 h and immuno-phenotyping was done using flow cytometry. Moreover, γδ T cells were isolated by Magnetic beads technology and mRNA expression of IL-17, IFN-γ, TGF-β and FOXP3 were analyzed by real-time PCR (qPCR) and cytokine was estimated in the culture supernatant by ELISA.

RESULTS

γδ T cells were significantly increased in both Reversal reaction (RR) and Erythema nodosum leprosum (ENL) reaction patients. These cells produced significant amount of IL-17 and IFN-γ. Furthermore, CD3⁺TCRγδ⁺ T cells expressed transient FOXP3 with a low amount of TGF-β in both reactions as compared to stable patients. Moreover, low TGF-β producing TCR-γδ cells were associated with low phosphorylation of STAT5A.

CONCLUSION

This study will add to our understanding of the immunological features that mediate and regulate the pathogenesis of leprosy and may helpful to reduce the immuno-pathogenesis of leprosy reaction by targeting these cells.

Immunomodulatory Therapy of Visceral Leishmaniasis in Human Immunodeficiency Virus-Coinfected Patients

Patients with visceral leishmaniasis (VL)–human immunodeficiency virus (HIV) coinfection experience increased drug toxicity and treatment failure rates compared to VL patients, with more frequent VL relapse and death. In the era of VL elimination strategies, HIV coinfection is progressively becoming a key challenge, because HIV-coinfected patients respond poorly to conventional VL treatment and play an important role in parasite transmission. With limited chemotherapeutic options and a paucity of novel anti-parasitic drugs, new interventions that target host immunity may offer an effective alternative. In this review, we first summarize current views on how VL immunopathology is significantly affected by HIV coinfection. We then review current clinical and promising preclinical immunomodulatory interventions in the field of VL and discuss how these may operate in the context of a concurrent HIV infection. Caveats are formulated as these interventions may unpredictably impact the delicate balance between boosting of beneficial VL-specific responses and deleterious immune activation/hyperinflammation, activation of latent provirus or increased HIV-susceptibility of target cells. Evidence is lacking to prioritize a target molecule and a more detailed account of the immunological status induced by the coinfection as well as surrogate markers of cure and protection are still required. We do, however, argue that virologically suppressed VL patients with a recovered immune system, in whom effective antiretroviral therapy alone is not able to restore protective immunity, can be considered a relevant target group for an immunomodulatory intervention. Finally, we provide perspectives on the translation of novel theories on synergistic immune cell cross-talk into an effective treatment strategy for VL–HIV-coinfected patients.

Rapid and Slow Progressors Show Increased IL-6 and IL-10 Levels in the Pre-AIDS Stage of HIV Infection

Cytokines are intrinsically related to disease progression in HIV infection. We evaluated the plasma levels of Th1/Th2/Th17 cytokines in extreme progressors, including slow (SPs) and rapid (RPs) progressors, who were thus classified based on clinical and laboratory follow-up covering a period of time before the initiation of HAART, ranging from 93–136.5 months for SPs and 7.5–16.5 months for RPs. Analyses were also performed based on the different stages of HIV infection (chronic, pre-HAART individuals—subjects sampled before initiating HAART but who initiated therapy from 12 to 24 months—and those receiving HAART). The plasma cytokine levels of 16 HIV-infected rapid progressors and 25 slow progressors were measured using a Human Th1/Th2/Th17 CBA kit. The IL-6 and IL-10 plasma levels differed significantly between the stages of HIV infection. The IL-6 levels were higher in slow progressors pre-HAART than in chronically infected SPs and HIV-seronegative individuals. The IL-10 levels were higher in slow progressors pre-HAART than in slow progressors receiving HAART and HIV-seronegative controls, and in rapid progressors, the IL-10 levels were higher in pre-HAART subjects than in HIV-seronegative controls. The results reflect the changes in the cytokine profile occurring during different clinical stages in HIV+ subjects. Our results suggest an association between increased IL-6 and IL-10 levels and pre-HAART stages independent of the slow or rapid progression status of the subjects. Thus, increased IL-6 and IL-10 levels could indicate a global inflammatory status and could be used as markers of the disease course in HIV-infected individuals.

Cytometry, immunology, and HIV infection: three decades of strong interactions

Flow cytometry (FCM) has been extensively used to investigate immunological changes that occur from infection with the human immunodeficiency virus (HIV). This review describes some of the most relevant cellular and molecular changes in the immune system that can be detected by FCM during HIV infection. Finally, it will be discussed how this technology has facilitated the understanding not only of the biology of the virus but also of the mechanisms that the immune system activates to fight HIV and is allowing to monitor the efficacy of antiretroviral therapy.

The role of cytokines in the establishment, persistence and eradication of the HIV reservoir

HIV persists in cellular and anatomical reservoirs during Highly Active Antiretroviral Therapy (HAART). In vitro studies as well as in vivo observations have identified cytokines as important factors regulating the immunological and virological mechanisms involved in HIV persistence. Immunosuppressive cytokines might contribute to the establishment of viral latency by dampening T cell activation and HIV production, thereby creating the necessary immuno-virological condition for the establishment of a pool of latently infected cells. Other cytokines that are involved in the maintenance of memory CD4(+) T cells promote the persistence of these cells during HAART. Conversely, proinflammatory cytokines may favor HIV persistence by exacerbating low levels of ongoing viral replication in lymphoid tissues even after prolonged therapy. The ability of several cytokines to interfere with the molecular mechanisms responsible for HIV latency makes them attractive candidates for therapeutic strategies aimed at reducing the pool of latently infected cells. In this article, we review the role of cytokines in HIV persistence during HAART and discuss their role as potential eradicating agents.