Caspase-1 Activity in CD4 T Cells Is Downregulated Following Antiretroviral Therapy for HIV-1 Infection

The Association between IL-1β and IL-18 Levels, Gut Barrier Disruption, and Monocyte Activation during Chronic Simian Immunodeficiency Virus Infection and Long-Term Suppressive Antiretroviral Therapy

HIV-induced persistent immune activation is a key mediator of inflammatory comorbidities such as cardiovascular disease (CVD) and neurocognitive disorders. While a preponderance of data indicate that gut barrier disruption and microbial translocation are drivers of chronic immune activation, the molecular mechanisms of this persistent inflammatory state remain poorly understood. Here, utilizing the nonhuman primate model of Human Immunodeficiency Virus (HIV) infection with suppressive antiretroviral therapy (ART), we investigated activation of inflammasome pathways and their association with intestinal epithelial barrier disruption (IEBD). Longitudinal blood samples obtained from rhesus macaques with chronic SIV infection and long-term suppressive ART were evaluated for IEBD biomarkers, inflammasome activation (IL-1β and IL-18), inflammatory cytokines, and triglyceride (TG) levels. Activated monocyte subpopulations and glycolytic potential were investigated in peripheral blood mononuclear cells (PBMCs). During the chronic phase of treated SIV infection, elevated levels of plasma IL-1β and IL-18 were observed following the hallmark increase in IEBD biomarkers, intestinal fatty acid-binding protein (IFABP) and LPS-binding protein (LBP). Further, significant correlations of plasma IFABP levels with IL-1β and IL-18 were observed between 10 and 12 months of ART. Higher levels of sCD14, IL-6, and GM-CSF, among other inflammatory mediators, were also observed only during the long-term SIV + ART phase along with a trend of increase in the frequencies of activated CD14+CD16+ intermediate monocyte subpopulations. Lastly, we found elevated levels of blood TG and higher glycolytic capacity in PBMCs of chronic SIV-infected macaques with long-term ART. The increase in circulating IL-18 and IL-1β following IEBD and their significant positive correlation with IFABP suggest a connection between gut barrier disruption and inflammasome activation during chronic SIV infection, despite viral suppression with ART. Additionally, the increase in markers of monocyte activation, along with elevated TG and enhanced glycolytic pathway activity, indicates metabolic remodeling that could fuel metabolic syndrome. Further research is needed to understand the mechanisms by which gut dysfunction and inflammasome activation contribute to HIV-associated metabolic complications, enabling targeted interventions in people with HIV.

Granzyme B-activated IL18 potentiates αβ and γδ CAR T cell immunotherapy in a tumor-dependent manner

Interleukin (IL)18 is a potent pro-inflammatory cytokine that is activated upon caspase 1 cleavage of the latent precursor, pro-IL18. Therapeutic T cell armoring with IL18 promotes autocrine stimulation and positive modulation of the tumor microenvironment (TME). However, existing strategies are imperfect since they involve constitutive/poorly regulated activity or fail to modify the TME. Here, we have substituted the caspase 1 cleavage site within pro-IL18 with that preferred by granzyme B, yielding GzB-IL18. We demonstrate that GzB-IL18 is constitutively released but remains functionally latent unless chimeric antigen receptor (CAR) T cells are activated, owing to concomitant granzyme B release. Armoring with GzB-IL18 enhances cytolytic activity, proliferation, interferon (IFN)-γ release, and anti-tumor efficacy by a similar magnitude to constitutively active IL18. We also demonstrate that GzB-IL18 provides a highly effective armoring strategy for γδ CAR T cells, leading to enhanced metabolic fitness and significant potentiation of therapeutic activity. Finally, we show that constitutively active IL18 can unmask CAR T cell-mediated cytokine release syndrome in immunocompetent mice. By contrast, GzB-IL18 promotes anti-tumor activity and myeloid cell re-programming without inducing such toxicity. Using this stringent system, we have tightly coupled the biological activity of IL18 to the activation state of the host CAR T cell, favoring safer clinical implementation of this technology.

High IL-1β and IL-18 Levels Associate with Gut Barrier Disruption and Monocyte Activation During Chronic SIV Infection with Long-Term Suppressive Antiretroviral Therapy

HIV-induced persistent immune activation is a key mediator of inflammatory comorbidities such as cardiovascular disease (CVD) and neurocognitive disorders. While a preponderance of data indicate that gut barrier disruption and microbial translocation are drivers of chronic immune activation, the molecular mechanisms of this persistent inflammatory state remain poorly understood. Here, utilizing the nonhuman primate model of HIV infection with suppressive antiretroviral therapy (ART), we investigated activation of inflammasome pathways and their association with intestinal epithelial barrier disruption and CVD pathogenesis. Longitudinal blood samples obtained from rhesus macaques with chronic SIV infection and long-term suppressive ART were evaluated for biomarkers of intestinal epithelial barrier disruption (IEBD), inflammasome activation (IL-1β and IL-18), inflammatory cytokines, and triglyceride (TG) levels. Activated monocyte subpopulations and glycolytic potential were investigated in peripheral blood mononuclear cells (PBMCs). Higher plasma levels of IL-1β and IL-18 were observed following the hallmark increase in IEBD biomarkers, intestinal fatty acid-binding protein (IFABP) and LPS-binding protein (LBP), during the chronic phase of treated SIV infection. Further, significant correlations of plasma IFABP levels with IL-1β and IL-18 were observed between 10-12 months of ART. Higher levels of sCD14, IL-6, and GM-CSF, among other inflammatory mediators, were also observed only during the long-term SIV+ART phase along with a trend of increase in frequencies of activated CD14 + CD16 + intermediate monocyte subpopulations. Lastly, we found elevated levels of blood TG and higher glycolytic capacity in PBMCs of chronic SIV-infected macaques with long-term ART. The increase in circulating IL-18 and IL-1β following IEBD and their significant positive correlation with IFABP suggest a connection between gut barrier disruption and inflammasome activation during chronic SIV infection, despite viral suppression with ART. Additionally, the increase in markers of monocyte activation, along with elevated TG and enhanced glycolytic pathway activity, indicates metabolic remodeling that could accelerate CVD pathogenesis. Further research is needed to understand mechanisms by which gut dysfunction and inflammasome activation contribute to HIV-associated CVD and metabolic complications, enabling targeted interventions in people with HIV.

Exercise to Prevent Accelerated Vascular Aging in People Living With HIV

Given advances in antiretroviral therapy, the mortality rate for HIV infection has dropped considerably over recent decades. However, people living with HIV (PLWH) experience longer life spans coupled with persistent immune activation despite viral suppression and potential toxicity from long-term antiretroviral therapy use. Consequently, PLWH face a cardiovascular disease (CVD) risk more than twice that of the general population, making it the leading cause of death among this group. Here, we briefly review the epidemiology of CVD in PLWH highlighting disparities at the intersections of sex and gender, age, race/ethnicity, and the contributions of social determinants of health and psychosocial stress to increased CVD risk among individuals with marginalized identities. We then overview the pathophysiology of HIV and discuss the primary factors implicated as contributors to CVD risk among PLWH on antiretroviral therapy. Subsequently, we highlight the functional evidence of premature vascular dysfunction as an early pathophysiological determinant of CVD risk among PLWH, discuss several mechanisms underlying premature vascular dysfunction in PLWH, and synthesize current research on the pathophysiological mechanisms underlying accelerated vascular aging in PLWH, focusing on immune activation, chronic inflammation, and oxidative stress. We consider understudied aspects such as HIV-related changes to the gut microbiome and psychosocial stress, which may serve as mechanisms through which exercise can abrogate accelerated vascular aging. Emphasizing the significance of exercise, we review various modalities and their impacts on vascular health, proposing a holistic approach to managing CVD risks in PLWH. The discussion extends to critical future study areas related to vascular aging, CVD, and the efficacy of exercise interventions, with a call for more inclusive research that considers the diversity of the PLWH population.

Modulation of MAPK- and PI3/AKT-Dependent Autophagy Signaling by Stavudine (D4T) in PBMC of Alzheimer’s Disease Patients

Background: Aβ₄₂ deposition plays a pivotal role in AD pathogenesis by inducing the activation of microglial cells and neuroinflammation. This process is antagonized by microglia-mediated clearance of Aβ plaques. Activation of the NLRP3 inflammasome is involved in neuroinflammation and in the impairments of Aβ-plaque clearance. On the other hand, stavudine (D4T) downregulates the NLRP3 inflammasome and stimulates autophagy-mediated Aβ-clearing in a THP-1-derived macrophages. Methods: We explored the effect of D4T on Aβ autophagy in PBMC from AD patients that were primed with LPS and stimulated with Aβ oligomers in the absence/presence of D4T. We analyzed the NLRP3 activity by measuring NLRP3-ASC complex formation by AMNIS FlowSight and pro-inflammatory cytokine (IL-1β, IL-18 and Caspase-1) production by ELISA. The phosphorylation status of p38, ERK, AKT, p70, and the protein expression of CREB, LAMP2A, beclin-1, Caspase-3 and Bcl2 were analyzed by Western blot. Results: Data showed that D4T: (1) downregulates NLRP3 inflammasome activation and the production of down-stream pro-inflammatory cytokines in PBMC; (2) stimulates the phosphorylation of AKT, ERK and p70 as well as LAMP2A, beclin-1 and Bcl2 expression and reduces Caspase-3 expression, suggesting an effect of this compound on autophagy; (3) increases phospho-CREB, which is a downstream target of p-ERK and p-AKT, inducing anti-inflammatory cytokine production and resulting in a possible decrease of Aβ-mediated cytotoxicity; and (4) reduces the phosphorylation of p38, a protein involved in the production of pro-inflammatory cytokines and tau hyperphosphorylation. Conclusions: D4T reduces the activation of the NLRP3 inflammasome, and it might stimulate autophagy as well as the molecular mechanism that modulates Aβ cytotoxicity, and D4T might reduce inflammation in the cells of AD patients. It could be very interesting to check the possible beneficial effects of D4T in the clinical scenario.

Role of inflammasomes in HIV-1 infection and treatment

Although combined antiretroviral therapy (cART) is effective in inhibiting human immunodeficiency virus type 1 (HIV-1) replication, it does not eradicate the virus because small amounts of latent HIV-1 provirus persist in quiescent memory CD4⁺ T cells. Therefore, strategies for eradicating latent HIV-1 are urgently needed. Recently, several studies have reported that the inflammatory response and lymphocyte death induced by HIV-1 depend on inflammasomes and pyroptosis, suggesting that inflammasomes and pyroptosis have a vital role in HIV-1 infection and contribute to the eradication of latent HIV-1. In this review, we summarize current knowledge of the role of inflammasomes, including NLR family pyrin domain-containing protein 3 (NLRP3), caspase recruitment domain-containing protein 8 (CARD8), interferon-inducible protein 16 (IFI16), NLRP1, NLR family CARD domain-containing 4 (NLRC4), and absent in melanoma 2 (AIM2), in HIV-1 infection and discuss promising therapeutic strategies for HIV-1-associated diseases by targeting inflammasomes.

Research Progress on the Relationship between the NLRP3 Inflammasome and Immune Reconstitution in HIV-Infected Patients Receiving Antiretroviral Therapy

Human immunodeficiency virus (HIV) infection is characterized not only by severe immunodeficiency but also by persistent inflammation and immune activation. These characteristics persist in people living with HIV (PLHIV) receiving effective antiretroviral therapy (ART) and are associated with morbidity and mortality in nonacquired immunodeficiency syndrome (AIDS) events. ART can inhibit HIV replication and promote immune reconstitution, which is currently the most effective way to control AIDS. However, despite effective long-term ART and overall suppression of plasma HIV RNA level, PLHIV still shows chronic low-level inflammation. The exact mechanisms that trigger chronic inflammation are unknown. Activation of the inflammasome is essential for the host response to pathogens, and some recent studies have confirmed the role of the inflammasome in the pathogenesis of inflammatory diseases. The NLRP3 inflammasome has been widely studied, which is a pyrin domain-containing protein 3 belonging to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent studies suggest that inflammasome-mediated pyroptosis is associated with CD4+ T cell loss in the absence of persistent infectious HIV replication. This article reviews the mechanism of the NLRP3 inflammasome and its correlation with immune reconstitution in PLHIV treated with ART.

Atherosclerosis in HIV Patients: What Do We Know so Far?

For the past several decades, humanity has been dealing with HIV. This disease is one of the biggest global health problems. Fortunately, modern antiretroviral therapy allows patients to manage the disease, improving their quality of life and their life expectancy. In addition, the use of these drugs makes it possible to reduce the risk of transmission of the virus to almost zero. Atherosclerosis is another serious pathology that leads to severe health problems, including disability and, often, the death of the patient. An effective treatment for atherosclerosis has not yet been developed. Both types of immune response, innate and adaptive, are important components of the pathogenesis of this disease. In this regard, the peculiarities of the development of atherosclerosis in HIV carriers are of particular scientific interest. In this review, we have tried to summarize the data on atherosclerosis and its development in HIV carriers. We also looked at the classic therapeutic methods and their features concerning the concomitant diagnosis.

HIV-Related Immune Activation and Inflammation: Current Understanding and Strategies

Although antiretroviral therapy effectively controls human immunodeficiency virus (HIV) replication, a residual chronic immune activation/inflammation persists throughout the disease. This aberrant immune activation and inflammation are considered an accelerator of non-AIDS-related events and one of the driving forces of CD4⁺ T cell depletion. Unfortunately, HIV-associated immune activation is driven by various factors, while the mechanism of excessive inflammation has not been formally clarified. To date, several clinical interventions or treatment candidates undergoing clinical trials have been proposed to combat this systemic immune activation/inflammation. However, these strategies revealed limited results, or their nonspecific anti-inflammatory properties are similar to previous interventions. Here, we reviewed recent learnings of immune activation and persisting inflammation associated with HIV infection, as well as the current directions to overcome it. Of note, a more profound understanding of the specific mechanisms for aberrant inflammation is still imperative for identifying an effective clinical intervention strategy.

Association of cell free mitochondrial DNA and caspase-1 expression with disease severity and ARTs efficacy in HIV infection

HIV infection is a global health concern. Current HIV-diagnostics provide information about the disease progression and efficacy of anti-retroviral therapies (ARVs), but this information is very limited and sometimes imprecise. Present study assessed the potential role of mononuclear cell (MNC) death, expression of caspases (1&3) and cell free mitochondrial DNA (CF mt-DNA) in HIV infected individuals. Apoptosis, cell-count, expression of caspases and CF mt-DNA were measured through flow cytometry and qPCR, respectively, in HIV infected individuals (n = 120) divided in two groups i.e. ARVs-receiving (treated, n = 87), ART-naïve (untreated, n = 37) and healthy individuals (n = 47). Data showed significant (p < 0.0001) cell death in untreated individuals than treated and healthy individuals. CD4-positive T-cell percentage declined (p < 0.0001) in untreated as compared to treated individuals. Caspase-1, an indicator of pyroptosis, and CF mt-DNA were also elevated in untreated HIV infected individuals. Untreated individuals when administered with ARVs showed improved CD4-positive T-cell percentage, lower caspase-1, CF mt-DNA and cell death. Data elucidated positive co-relation between cell death and CF mt-DNA in treated and untreated HIV infected individuals. While CD4-positive T-cell percentage was negatively correlated with caspase-1 expression and CF mt-DNA. Elevated levels of CF mt-DNA and caspase-1 in HIV infected individuals, positive correlation between cell death and CF mt-DNA, negative correlation of CD4-positive T-cell percentage with CF mt-DNA and caspase-1 expression clearly indicated the potential of CF mt-DNA and caspase-1 as a novel disease progression and ARTs effectiveness biomarkers in HIV.

NLRP3 inflammasome induces CD4+ T cell loss in chronically HIV-1-infected patients

Chronic HIV-1 infection is generally characterized by progressive CD4+ T cell depletion due to direct and bystander death that is closely associated with persistent HIV-1 replication and an inflammatory environment in vivo. The mechanisms underlying the loss of CD4+ T cells in patients with chronic HIV-1 infection are incompletely understood. In this study, we simultaneously monitored caspase-1 and caspase-3 activation in circulating CD4+ T cells, which revealed that pyroptotic and apoptotic CD4+ T cells are distinct cell populations with different phenotypic characteristics. Levels of pyroptosis and apoptosis in CD4+ T cells were significantly elevated during chronic HIV-1 infection, and decreased following effective antiretroviral therapy. Notably, the occurrence of pyroptosis was further confirmed by elevated gasdermin D activation in lymph nodes of HIV-1-infected individuals. Mechanistically, caspase-1 activation closely correlated with the inflammatory marker expression and was shown to occur through NLRP3 inflammasome activation driven by virus-dependent and/or -independent ROS production, while caspase-3 activation in CD4+ T cells was more closely related to T cell activation status. Hence, our findings show that NLRP3-dependent pyroptosis plays an essential role in CD4+ T cell loss in HIV-1-infected patients and implicate pyroptosis signaling as a target for anti-HIV-1 treatment.

Differences in pyroptosis of recent thymic emigrants CD4+ T Lymphocytes in ART-treated HIV-positive patients are influenced by sex

Pyroptosis cell death in recent thymus emigrants (RTE) CD4+ T lymphocytes plays an important role on HIV-1 infection as a cause of CD4+ T cell depletion, being influenced by several factors, among them, the sex. Thus, the aim of this study was evaluated pyroptosis levels in RTE CD4+ T lymphocytes of individuals under antiretroviral therapy (ART) stratified by sex. Thirty-seven ART-treated HIV-positive patients (22 females and 15 males) and 12 (seven females and five males) clinically health subjects were recruited. Analysis by flow-cytometry of RTE CD4+ cells (CD4+ CD31+ /fluorescent-labeled inhibitors of caspases-Caspase-1+) were performed. Clinical and sociodemographic aspects were also evaluated from medical records. We observed statistically higher levels of pyroptosis RTE CD4+ T cells in male individuals (69.3%) compared with female group (39.1%) (P = 0.0356). Pre- and post-treatment CD4+ T cell counts were also higher in women than men (P = 0.004 and P = 0.012, respectively). Our data provides important evidence of the sex as a potential predictor of immunological reconstitution in ART-treated individuals.

Effects of Integrase Inhibitor-Based ART on the NLRP3 Inflammasome Among ART-Naïve People With HIV

The NOD-like receptor protein family pyrin domain containing 3 (NLRP3) inflammasome, activated in the setting of HIV, contributes to pro-atherogenic inflammation. Among antriretroviral therapy–naïve people with HIV (vs controls), levels of caspase-1—a key component of the NLRP3 inflammasome—were significantly increased. Six months of elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate significantly decreased caspase-1 levels in association with CD4+/CD8+ ratio recovery.

Trial registration. ClinicalTrials.gov NCT 01766726.

Role of Smad3 inhibitor and the pyroptosis pathway in spinal cord injury

The aim of the present study was to investigate the role of Smad3 inhibitors and the pyroptosis pathway in spinal cord injury, and to determine the underlying mechanism. The pyroptosis signaling pathway may be involved in spinal cord injury during the recovery period. Smad3 inhibitor may serve a role in alleviating spinal cord injury by reducing the pyroptosis of neurons, which is induced by caspase-1, absent in melanoma-2 or NOD-like receptors protein-1 during the recovery period of spinal cord injury. In the present study, spinal cord injury was alleviated by caspase-1 and Smad3 inhibitors. Therefore, a Smad3 inhibitor could relieve spinal cord injury in mice by directly downregulating caspase-1 and reducing neuron pyroptosis following spinal cord injury during the recovery period.

NLRP3 Inflammasome Signaling as a Link Between HIV-1 Infection and Atherosclerotic Cardiovascular Disease

36.9 million people worldwide are living with HIV-1. The disease remains incurable and HIV-infected patients have increased risk of atherosclerosis. Inflammation is a key driver of atherosclerosis, but no targeted molecular therapies have been developed to reduce cardiovascular risk in people with HIV-1 (PWH). While the mechanism is unknown, there are several important inflammatory signaling events that are implicated in the development of chronic inflammation in PWH and in the inflammatory changes that lead to atherosclerosis. Here we describe the pro-inflammatory state of HIV-1 infection that leads to increased risk of cardiovascular disease, the role of the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome in HIV-1 infection, the role of the NLRP3 inflammasome in cardiovascular disease (CVD), and outline a model whereby HIV-1 infection can lead to atherosclerotic disease through NLRP3 inflammasome activation. Our discussion highlights the literature supporting HIV-1 infection as a stimulator of the NLRP3 inflammasome as a driver of atherosclerosis.

Methamphetamine Enhances HIV-1 Replication in CD4+ T-Cells via a Novel IL-1β Auto-Regulatory Loop

Methamphetamine (Meth) abuse is a worldwide public health problem and contributes to HIV-1 pathobiology and poor adherence to anti-retroviral therapies. Specifically, Meth is posited to alter molecular mechanisms to provide a more conducive environment for HIV-1 replication and spread. Enhanced expression of inflammatory cytokines, such as Interleukin-1β (IL-1β), has been shown to be important for HIV-1 pathobiology. In addition, microRNAs (miRNAs) play integral roles in fine-tuning the innate immune response. Notably, the effects of Meth abuse on miRNA expression are largely unknown. We studied the effects of Meth on IL-1β and miR-146a, a well-characterized member of the innate immune signaling network. We found that Meth induces miR-146a and triggers an IL-1β auto-regulatory loop to modulate innate immune signaling in CD4⁺ T-cells. We also found that Meth enhances HIV-1 replication via IL-1 signaling. Our results indicate that Meth activates an IL-1β feedback loop to alter innate immune pathways and favor HIV-1 replication. These observations offer a framework for designing targeted therapies in HIV-infected, Meth using hosts.

Inflammasome in HIV infection: Lights and shadows

The importance of inflammasome, and related cytokines IL-1ß and IL-18, in host defense against pathogens is well documented, however, at the same time, dysregulation of inflammasome has been associated to multifactorial diseases characterized by chronic inflammation (i.e.: metabolic disorders, cardiovascular diseases, neurodegenerative diseases, autoimmunity, cancer). Inflammasome activation has been described in response to HIV-1 and possibly contributes to the resistance against virus establishment, however, on the other hand, when viral infection becomes chronic, independently from antiretroviral therapy, the increase constitutive activation of inflammasome has been eventually associated to a worse prognosis, raising the question about the role played by inflammasome and/or some specific receptors in this context. Due to the chance to imply targeted therapies that inhibit inflammasome activation and/or cytokines release, it will be important to define the impact of the complex in the pathogenesis of HIV. The purpose of this review is to depict the double-faced inflammasome role in HIV-1 infection, trying to unveil whether besides its role in first line defense against the virus, it exerts a harmful effect during the chronic phase of infection.

Gasdermin D: Evidence of pyroptosis in spontaneous preterm labor with sterile intra-amniotic inflammation or intra-amniotic infection

PROBLEM

Pyroptosis, inflammatory programmed cell death, is initiated through the inflammasome and relies on the pore-forming actions of the effector molecule gasdermin D. Herein, we investigated whether gasdermin D is detectable in women with spontaneous preterm labor and sterile intra-amniotic inflammation or intra-amniotic infection.

METHOD OF STUDY

Amniotic fluid samples (n = 124) from women with spontaneous preterm labor were subdivided into the following groups: (a) those who delivered at term (n = 32); and those who delivered preterm (b) without intra-amniotic inflammation (n = 41), (c) with sterile intra-amniotic inflammation (n = 32), or (d) with intra-amniotic infection (n = 19), based on amniotic fluid IL-6 concentrations and the microbiological status of amniotic fluid (culture and PCR/ESI-MS). Gasdermin D concentrations were measured using an ELISA kit. Multiplex immunofluorescence staining was also performed to determine the expression of gasdermin D, caspase-1, and interleukin-1β in the chorioamniotic membranes. Flow cytometry was used to detect pyroptosis (active caspase-1) in decidual cells from women with preterm labor and birth.

RESULTS

(a) Gasdermin D was detected in the amniotic fluid and chorioamniotic membranes from women who underwent spontaneous preterm labor/birth with either sterile intra-amniotic inflammation or intra-amniotic infection, but was rarely detected in those without intra-amniotic inflammation. (b) Amniotic fluid concentrations of gasdermin D were higher in women with intra-amniotic infection than in those with sterile intra-amniotic inflammation, and its expression in the chorioamniotic membranes was associated with caspase-1 and IL-1β (inflammasome mediators). (c) Decidual stromal cells and leukocytes isolated from women with preterm labor and birth are capable of undergoing pyroptosis given their expression of active caspase-1.

CONCLUSION

Pyroptosis can occur in the context of sterile intra-amniotic inflammation and intra-amniotic infection in patients with spontaneous preterm labor and birth.

Caspase-1 Activation Is Related With HIV-Associated Atherosclerosis in an HIV Transgenic Mouse Model and HIV Patient Cohort

OBJECTIVE

Atherosclerotic cardiovascular disease (ASCVD) is an increasing cause of morbidity and mortality in people with HIV since the introduction of combination antiretroviral therapy. Despite recent advances in our understanding of HIV ASCVD, controversy still exists on whether this increased risk of ASCVD is due to chronic HIV infection or other risk factors. Mounting biomarker studies indicate a role of monocyte/macrophage activation in HIV ASCVD; however, little is known about the mechanisms through which HIV infection mediates monocyte/macrophage activation in such a way as to engender accelerated atherogenesis. Here, we experimentally investigated whether HIV expression is sufficient to accelerate atherosclerosis and evaluated the role of caspase-1 activation in monocytes/macrophages in HIV ASCVD. Approach and Results: We crossed a well-characterized HIV mouse model, Tg26 mice, which transgenically expresses HIV-1, with ApoE-/- mice to promote atherogenic conditions (Tg26+/-/ApoE-/-). Tg26+/-/ApoE-/- have accelerated atherosclerosis with increased caspase-1 pathway activation in inflammatory monocytes and atherosclerotic vasculature compared with ApoE-/-. Using a well-characterized cohort of people with HIV and tissue-banked aortic plaques, we documented that serum IL (interleukin)-18 was higher in people with HIV compared with non-HIV-infected controls, and in patients with plaques, IL-18 levels correlated with monocyte/macrophage activation markers and noncalcified inflammatory plaques. In autopsy-derived aortic plaques, caspase-1+ cells and CD (clusters of differentiation) 163+ macrophages correlated.

CONCLUSIONS

These data demonstrate that expression of HIV is sufficient to accelerate atherogenesis. Further, it highlights the importance of caspase-1 and monocyte/macrophage activation in HIV atherogenesis and the potential of Tg26+/-/ApoE-/- as a tool for mechanistic studies of HIV ASCVD.

Cellular Determinants of HIV Persistence on Antiretroviral Therapy

The era of antiretroviral therapy has made HIV-1 infection a manageable chronic disease for those with access to treatment. Despite treatment, virus persists in tissue reservoirs seeded with long-lived infected cells that are resistant to cell death and immune recognition. Which cells contribute to this reservoir and which factors determine their persistence are central questions that need to be answered to achieve viral eradication. In this chapter, we describe how cell susceptibility to infection, resistance to cell death, and immune-mediated killing as well as natural cell life span and turnover potential are central components that allow persistence of different lymphoid and myeloid cell subsets that were recently identified as key players in harboring latent and actively replicating virus. The relative contribution of these subsets to persistence of viral reservoir is described, and the open questions are highlighted.

Nucleic Acid Sensing in Mammals and Plants: Facts and Caveats

The accumulation of nucleic acids in aberrant compartments is a signal of danger: fragments of cytosolic or extracellular self-DNA indicate cellular dysfunctions or disruption, whereas cytosolic fragments of nonself-DNA or RNA indicate infections. Therefore, nucleic acids trigger immunity in mammals and plants. In mammals, endosomal Toll-like receptors (TLRs) sense single-stranded (ss) or double-stranded (ds) RNA or CpG-rich DNA, whereas various cytosolic receptors sense dsDNA. Although a self/nonself discrimination could favor targeted immune responses, no sequence-specific sensing of nucleic acids has been reported for mammals. Specific immune responses to extracellular self-DNA versus DNA from related species were recently reported for plants, but the underlying mechanism remains unknown. The subcellular localization of mammalian receptors can favor self/nonself discrimination based on the localization of DNA fragments. However, autoantibodies and diverse damage-associated molecular patterns (DAMPs) shuttle DNA through membranes, and most of the mammalian receptors share downstream signaling elements such as stimulator of interferon genes (STING) and the master transcription regulators, nuclear factor (NF)-κB, and interferon regulatory factor 3 (IRF3). The resulting type I interferon (IFN) response stimulates innate immunity against multiple threats-from infection to physical injury or endogenous DNA damage-all of which lead to the accumulation of eDNA or cytoplasmatic dsDNA. Therefore, no or only low selective pressures might have favored a strict self/nonself discrimination in nucleic acid sensing. We conclude that the discrimination between self- and nonself-DNA is likely to be less strict-and less important-than assumed originally.