Spontaneous Control of SIV Replication Does Not Prevent T Cell Dysregulation and Bacterial Dissemination in Animals Co-Infected with M. tuberculosis

Deciphering lung granulomas in HIV & TB co-infection: unveiling macrophages aggregation with IL6R/STAT3 activation

Tuberculosis (TB) remains a leading cause of mortality among individuals coinfected with HIV, characterized by progressive pulmonary inflammation. Despite TB's hallmark being focal granulomatous lung lesions, our understanding of the histopathological features and regulation of inflammation in HIV & TB coinfection remains incomplete. In this study, we aimed to elucidate these histopathological features through an immunohistochemistry analysis of HIV & TB co-infected and TB patients, revealing marked differences. Notably, HIV & TB granulomas exhibited aggregation of CD68 + macrophage (Mφ), while TB lesions predominantly featured aggregation of CD20+ B cells, highlighting distinct immune responses in coinfection. Spatial transcriptome profiling further elucidated CD68+ Mφ aggregation in HIV & TB, accompanied by activation of IL6 pathway, potentially exacerbating inflammation. Through multiplex immunostaining, we validated two granuloma types in HIV & TB versus three in TB, distinguished by cell architecture. Remarkably, in the two types of HIV & TB granulomas, CD68 + Mφ highly co-expressed IL6R/pSTAT3, contrasting TB granulomas' high IFNGRA/SOCS3 expression, indicating different signaling pathways at play. Thus, activation of IL6 pathway may intensify inflammation in HIV & TB-lungs, while SOCS3-enriched immune microenvironment suppresses IL6-induced over-inflammation in TB. These findings provide crucial insights into HIV & TB granuloma formation, shedding light on potential therapeutic targets, particularly for granulomatous pulmonary under HIV & TB co-infection. Our study emphasizes the importance of a comprehensive understanding of the immunopathogenesis of HIV & TB coinfection and suggests potential avenues for targeting IL6 signaling with SOCS3 activators or anti-IL6R agents to mitigate lung inflammation in HIV & TB coinfected individuals.

Antibody glycosylation correlates with disease progression in SIV-Mycobacterium tuberculosis coinfected cynomolgus macaques

Objectives

Tuberculosis (TB) remains a substantial cause of morbidity and mortality among people living with human immunodeficiency virus (HIV) worldwide. However, the immunological mechanisms associated with the enhanced susceptibility among HIV-positive individuals remain largely unknown.

Methods

Here, we used a simian immunodeficiency virus (SIV)/TB-coinfection Mauritian cynomolgus macaque (MCM) model to examine humoral responses from the plasma of SIV-negative (n = 8) and SIV-positive (n = 7) MCM 8-week postinfection with Mycobacterium tuberculosis (Mtb).

Results

Antibody responses to Mtb were impaired during SIV coinfection. Elevated inflammatory bulk IgG antibody glycosylation patterns were observed in coinfected macaques early at 8-week post-Mtb infection, including increased agalactosylation (G0) and reduced di-galactosylation (G2), which correlated with endpoint Mtb bacterial burden and gross pathology scores, as well as the time-to-necropsy.

Conclusion

These studies suggest that humoral immunity may contribute to control of TB disease and support growing literature that highlights antibody Fc glycosylation as a biomarker of TB disease progression.

Immune Responses in Lung Granulomas during Mtb/HIV Co-Infection: Implications for Pathogenesis and Therapy

HIV and TB are the cause of significant worldwide mortality and pose a grave danger to the global public health. TB is the leading cause of death in HIV-infected persons, with one in four deaths attributable to TB. While the majority of healthy individuals infected with M. tuberculosis (Mtb) are able to control the infection, co-infection with HIV increases the risk of TB infection progressing to TB disease by over 20-fold. While antiretroviral therapy (ART), the cornerstone of HIV care, decreases the incidence of TB in HIV-uninfected people, this remains 4- to 7-fold higher after ART in HIV-co-infected individuals in TB-endemic settings, regardless of the duration of therapy. Thus, the immune control of Mtb infection in Mtb/HIV-co-infected individuals is not fully restored by ART. We do not fully understand the reasons why Mtb/HIV-co-infected individuals maintain a high susceptibility to the reactivation of LTBI, despite an effective viral control by ART. A deep understanding of the molecular mechanisms that govern HIV-induced reactivation of TB is essential to develop improved treatments and vaccines for the Mtb/HIV-co-infected population. We discuss potential strategies for the mitigation of the observed chronic immune activation in combination with both anti-TB and anti-retroviral approaches.

Host Immunity to Mycobacterium tuberculosis Infection Is Similar in Simian Immunodeficiency Virus (SIV)-Infected, Antiretroviral Therapy-Treated and SIV-Naïve Juvenile Macaques

Pre-existing HIV infection increases tuberculosis (TB) risk in children. Antiretroviral therapy (ART) reduces, but does not abolish, this risk in children with HIV. The immunologic mechanisms involved in TB progression in both HIV-naive and HIV-infected children have not been explored. Much of our current understanding is based on human studies in adults and adult animal models. In this study, we sought to model childhood HIV/Mycobacterium tuberculosis (Mtb) coinfection in the setting of ART and characterize T cells during TB progression. Macaques equivalent to 4 to 8 year-old children were intravenously infected with SIVmac239M, treated with ART 3 months later, and coinfected with Mtb 3 months after initiating ART. SIV-naive macaques were similarly infected with Mtb alone. TB pathology and total Mtb burden did not differ between SIV-infected, ART-treated and SIV-naive macaques, although lung Mtb burden was lower in SIV-infected, ART-treated macaques. No major differences in frequencies of CD4+ and CD8+ T cells and unconventional T cell subsets (Vγ9+ γδ T cells, MAIT cells, and NKT cells) in airways were observed between SIV-infected, ART-treated and SIV-naive macaques over the course of Mtb infection, with the exception of CCR5+ CD4+ and CD8+ T cells which were slightly lower. CD4+ and CD8+ T cell frequencies did not differ in the lung granulomas. Immune checkpoint marker levels were similar, although ki-67 levels in CD8+ T cells were elevated. Thus, ART treatment of juvenile macaques, 3 months after SIV infection, resulted in similar progression of Mtb and T cell responses compared to Mtb in SIV-naive macaques.

Immune checkpoint modulating T cells and NK cells response to Mycobacterium tuberculosis infection

Many subversive mechanisms promote the occurrence and development of chronic infectious diseases and cancer, among which the down-regulated expression of immune-activating receptors and the enhanced expression of immune-inhibitory receptors accelerate the occurrence and progression of the disease. Recently, the use of immune checkpoint inhibitors has shown remarkable efficacy in the treatment of tumors in multiple organs. However, the expression of immune checkpoint molecules on natural killer (NK) cells by Mycobacterium tuberculosis (Mtb) infection and its impact on NK cell effector functions have been poorly studied. In this review, we focus on what is currently known about the expression of various immune checkpoints in NK cells following Mtb infection and how it alters NK cell-mediated host cytotoxicity and cytokine secretion. Unraveling the function of NK cells after the infection of host cells by Mtb is crucial for a comprehensive understanding of the innate immune mechanism of NK cells involved in tuberculosis and the evaluation of the efficacy of immunotherapies using immune checkpoint inhibitors to treat tuberculosis. In view of some similarities in the immune characteristics of T cells and NK cells, we reviewed the molecular mechanism of the interaction between T cells and Mtb, which can help us to further understand and explore the specific interaction mechanism between NK cells and Mtb.

Systems biology approaches to investigate the role of granulomas in TB-HIV coinfection

The risk of active tuberculosis disease is 15-21 times higher in those coinfected with human immunodeficiency virus-1 (HIV) compared to tuberculosis alone, and tuberculosis is the leading cause of death in HIV+ individuals. Mechanisms driving synergy between Mycobacterium tuberculosis (Mtb) and HIV during coinfection include: disruption of cytokine balances, impairment of innate and adaptive immune cell functionality, and Mtb-induced increase in HIV viral loads. Tuberculosis granulomas are the interface of host-pathogen interactions. Thus, granuloma-based research elucidating the role and relative impact of coinfection mechanisms within Mtb granulomas could inform cohesive treatments that target both pathogens simultaneously. We review known interactions between Mtb and HIV, and discuss how the structure, function and development of the granuloma microenvironment create a positive feedback loop favoring pathogen expansion and interaction. We also identify key outstanding questions and highlight how coupling computational modeling with in vitro and in vivo efforts could accelerate Mtb-HIV coinfection discoveries.

Innate cell markers that predict anti-HIV neutralizing antibody titers in vaccinated macaques

Given the time and resources invested in clinical trials, innovative prediction methods are needed to decrease late-stage failure in vaccine development. We identify combinations of early innate responses that predict neutralizing antibody (nAb) responses induced in HIV-Env SOSIP immunized cynomolgus macaques using various routes of vaccine injection and adjuvants. We analyze blood myeloid cells before and 24 h after each immunization by mass cytometry using a three-step clustering, and we discriminate unique vaccine signatures based on HLA-DR, CD39, CD86, CD11b, CD45, CD64, CD14, CD32, CD11c, CD123, CD4, CD16, and CADM1 surface expression. Various combinations of these markers characterize cell families positively associated with nAb production, whereas CADM1-expressing cells are negatively associated (p < 0.05). Our results demonstrate that monitoring immune signatures during early vaccine development could assist in identifying biomarkers that predict vaccine immunogenicity.

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HIV-Env SOSIP trimers induce neutralizing antibodies in cynomolgus macaques

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Vaccine-induced innate cells changes are characterized using mass cytometry

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Adjuvant and route of immunization influence early innate signatures in vaccinated NHP

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Early innate cell signatures predict neutralizing antibody levels