Preface.

Chronic viruses such as HIV and hepatitis are a major health concern worldwide. As an organ constantly exposed to the external environment, the gastrointestinal tract (GIT) must constantly balance suppressive and inflammatory immunity, making it an ideal organ for virus persistence. Yet despite its importance, chronic virus infection of the GIT and its ramifications towards host immunity remains poorly understood. We recently discovered that the GIT is a long-term reservoir for chronic lymphocytic choriomeningitis virus (LCMV); persisting well after virus is cleared from the blood and other peripheral tissues. To identify host and microbial alterations that facilitate chronic GIT infection we performed high dimensional CyTOF analysis, 16s rRNA-seq and next generation sequencing. Primary infection induced acute CD4 T cell ablation and chronic infection promoted Treg outgrowth, which was associated with viral persistence. Interestingly, chronic infection led to acute GI pathology and dysbiosis, with long-term infection enhancing susceptibility to IBD. Transcriptional signatures indicated enhanced type I interferon induced inflammation and metabolic changes associated with immune exhaustion. Interestingly, upstream regulators of GIT immunity were shared in chronic LCMV, HIV and SIV, indicating the induction of conserved pathways across multiple viral infections. Finally, we demonstrate the efficacy of immunotherapeutic targets and cell depletions to control the long-lived chronic GIT reservoir. Ultimately our studies define molecular, cellular and microbial impacts of chronic virus infection to alter GI function and identify potential immunotherapeutic strategies to control virus in this long-lived reservoir.

During chronic HIV-1 infection, the upregulation of immune checkpoints (ICs) on lymphocytes contributes to persistent immune dysfunction, T-cell exhaustion, and inadequate virological control, highlighting the potential role of ICs in HIV functional cure strategy. Despite extensive research on ICs, the expression dynamics and immunological impact of ICs in natural HIV/SHIV infection, particularly among antiretroviral therapy (ART)-free elite controllers (ECs), remain poorly understood. In this study, we monitored a cohort of SHIVSF162P3-infected rhesus macaques (RMs), identifying four ECs and four progressors (PGs) through longitudinal evaluation. We observed low-level expression of ICs in both peripheral blood and lymph nodes of ECs, characterized by a particularly pronounced restriction in the expression of TIGIT and BTLA. This attenuated IC profile correlated with enhanced T-cell functionality, reduced exhaustion markers, and reduced viral reservoirs in peripheral and lymphoid tissues. Transcriptomic profiling revealed that TIGIT is a critical checkpoint marker involved in multiple synergistic cofunctions related to HIV/SIV-specific immune regulation. Collectively, our findings establish a dual role for ICs in perpetuating T-cell exhaustion and viral reservoir persistence, paving the way for IC blockade in future HIV cure strategies.IMPORTANCERhesus macaques spontaneously controlling simian-human immunodeficiency virus (SHIV) without antiretroviral therapy have low-level expression of immune molecules (ICs), characterized by TIGIT and BTLA. These molecules are linked to enhanced immune function and reduced viral presence in peripheral blood and lymph nodes. Transcriptomic profiling revealed that TIGIT is a critical checkpoint marker involved in multiple synergistic cofunctions related to HIV/SIV-specific immune regulation in both humans and macaques. Blocking TIGIT improved polyfunctional T-cell responses, thereby offering a potential new treatment strategy and providing critical insights for developing a functional HIV cure.

Chronic human immunodeficiency virus (HIV) infection was characterized by progressive immune dysfunction, in which CD4+ T cell depletion and exhaustion play pivotal roles. CD4+ T cell exhaustion, marked by impaired proliferative capacity and sustained expression of inhibitory receptors, contributes to poor immune reconstitution despite effective antiretroviral therapy. Biomarkers such as programmed cell death protein 1 (PD-1), T cell immunoglobulin and mucin-domain containing-3 (TIM-3), cytotoxic T lymphocyte antigen 4 (CTLA-4), and lymphocyte activation gene 3 (LAG-3) had been proposed as key indicators of T cell dysfunction, while soluble inflammatory mediators provide complementary prognostic information. The purpose of this review was to critically evaluate the prognostic implications of CD4+ T cell exhaustion biomarkers in chronic HIV infection, focusing on their utility for predicting disease progression, therapeutic outcomes, and comorbid risks. A narrative synthesis was conducted using PubMed, Scopus, and Web of Science databases for studies published between 2012 and 2025, including clinical trials, mechanistic investigations, and translational studies of immune biomarkers in HIV. Evidence indicated that high expression of PD-1 and TIM-3 correlates with accelerated CD4+ decline, higher viral reservoirs, and increased risk of opportunistic infections. Combinatorial biomarker profiling enhanced prognostic accuracy beyond single markers. Importantly, exhaustion biomarkers also predicted responsiveness to immune-based therapies and vaccine strategies. Despite their promise, variability across cohorts and technical limitations hindered standardization. CD4+ T cell exhaustion biomarkers provided valuable insights into HIV pathogenesis and may guide prognostic assessment and therapeutic innovation. Keywords: HIV, CD4+ T cell, Immune exhaustion, Biomarkers, Prognosis.

In recent years, exosomes have emerged as crucial mediators of intercellular communication, fundamentally altering our understanding of biological signaling networks. These nano-sized extracellular vesicles (EVs), derived from multivesicular bodies and secreted by nearly all cell types, carry a diverse cargo, including proteins, lipids, RNA, and DNA. The special issue "Exosome-Mediated Intercellular Communications: Immune Stimulation and Suppression" aims to explore the multifaceted roles of exosomes in modulating immune responses, highlighting their potential in immunotherapy, diagnostics, and pathophysiology. This editorial provides an overview of the advances presented in this collection, underscores the significance of these findings, and sets the stage for future research directions.The issue opens with a study exploring the diagnostic potential of exosomes in trauma. Schindler et al. identify novel EV biomarkers specific to traumatic brain injury (TBI), demonstrating how EVs with distinct protein profiles (e.g., CD13 and MOG) correlate with neurological outcomes. This work emphasizes the clinical value of EVs as minimally invasive tools for early diagnostics in polytrauma settings, illustrating the interplay between injuryspecific exosome-mediated signaling and immune modulation.Exosomes have recently been recognized as significant contributors to disease pathogenesis. In this context, the study conducted by Kobiela et al. highlights the role of keratinocyte-derived small extracellular vesicles (sEVs) in allergic skin inflammation, specifically regarding filaggrin insufficiency. Their study reveals that sEVs act as antigenic sources for CD1arestricted T cells, promoting a type 2 immune bias that exacerbates atopic dermatitis. By linking lipidomic alterations in sEVs to immune dysregulation, the authors provide a mechanistic understanding of how exosome-mediated communication perpetuates skin inflammation, presenting opportunities for targeted interventions in allergic disorders.Guo et al. delve into the immune-regulatory roles of exosomal microRNAs (miRNAs) in heart failure (HF). These miRNAs mediate the crosstalk between cardiac and immune cells, modulating processes like inflammation, fibrosis, and cardiac dysfunction. Highlighted as potential biomarkers and therapeutic agents, exosomal miRNAs could redefine diagnostic and therapeutic paradigms in HF, paving the way for more personalized approaches in cardiovascular medicine.Exosomes have emerged as a promising candidate for various therapeutic applications across a range of diseases. Moreover, they possess the essential characteristics of an effective drug delivery system, enhancing their potential in medical treatments. In this context, a study by Wang et al. provided compelling evidence on the role of miR-146a-enriched fibroblast-like synoviocyte-derived exosomes (FLS-Exos) in alleviating osteoarthritis (OA). By targeting the Toll-like receptor 4/TRAF6/NF-κB signaling pathway, these exosomes reduced cartilage degradation and shifted synovial macrophages from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. This innovative approach highlights the potential of miR-146a as a therapeutic agent in OA, emphasizing the role of exosome-associated microRNAs in immune regulation and tissue repair.Menay et al. explore the immunogenic potential of EVs derived from antigen-presenting cells (APCs) pulsed with foot-and-mouth disease virus (FMDV) antigens. These EVs carry viral proteins capable of stimulating both B and T cell responses, providing a new avenue for vaccine development. The ability of these vesicles to induce lymphocyte expansion, particularly in antigen-primed splenocytes, underscores their role as a platform for next-generation antiviral vaccines.In another review, Mei et al. explore the therapeutic potential of mesenchymal stem cells (MSCs) as vehicles for drug delivery and immune modulation. The authors emphasize MSCs' tumor tropism and homing ability, qualities that render them effective carriers for targeted therapies. They further discuss the promise of MSC derivatives, such as MSC-derived EVs and MSC cell membrane-coated nanoparticles, highlighting how these innovative strategies can enhance precision and efficacy in the treatment of inflammatory, fibrotic, and oncologic conditions. Despite the promise, challenges such as scalability and reproducibility must be addressed to ensure clinical translation.The review by Xiu et al. sheds light on the crucial roles of bacterial membrane vesicles (MVs) in regulating bacterial physiology, environmental adaptation, and pathogenic processes. MVs are key players in interkingdom communication, influencing microbial community dynamics and host-pathogen interactions. The authors highlight their potential applications in developing novel antimicrobial strategies and vaccines, underscoring the importance of understanding bacterial MVs in both environmental and clinical contexts.The collection collectively demonstrates the multifaceted nature of exosomes, from their ability to stimulate immune activity to their role in suppressing inflammatory pathways. The therapeutic and diagnostic innovations explored here highlight the transformative potential of EV research, paving the way for novel applications in immunology and beyond.We hope this special issue inspires future investigations into the intricate mechanisms of exosome-mediated communication and their implications for immune health and disease management. As the field continues to evolve, the convergence of clinical insights and translational innovations promises to redefine therapeutic paradigms.For more details on these contributions, explore the articles in this issue on the Frontiers in Immunology website.

Introduction: Studies from our laboratory have shown that global warming and the low level EMF pollution results in increased endosymbiotic archaeal growth. The archaea can produce methanogenesis from hydrogen and carbon dioxide as well as from acetate. The human body methanogenesis can result in more global warming. Global warming is initially triggered by carbon dioxide and EMF pollution produced by homo sapien industrialization. It is carried forward by human endosymbiotic archaeal overgrowth and methanogenesis. The archaea can induce stem cell conversion and neanderthalisation of the human species. The archaea catabolises cholesterol generating digoxin which can modulate RNA editing and magnesium deficiency resulting in reverse transcriptase inhibition. The archaeal cholesterol catabolism can deplete the membrane rafts of the CD4 cell of cholesterol impeding the entry of the retrovirus into the cell. The archaea can produce permanent immune activation producing resistance to viral and bacterial infection. The archaeal cholesterol catabolism depletes tissue cholesterol producing vitamin D deficiency and immune activation. Thus archaeal overgrowth results in retroviral resistance and generation of the Neanderthal phenotype. The endosymbiotic archaea can secrete virus like RNA and DNA particles. The endosymbiotic archaea can induce uncoupling proteins inhibiting mitochondrial oxidative phosphorylation and generating ROS. The endosymbiotic archaeal magnetite can generate low level of EMF. The low level of EMF and ROS are genotoxic and produce breakages in hotspots of chromosome. It can also trigger rearrangements in hotspots of chromosome inhabited by retroviral and non-retroviral elements producing their expression. The archaeal secreted DNA and RNA viroids can recombine with the expressed retroviral, non-retroviral elements and other genomic segments of the human chromosome generating new RNA and DNA viruses. Thus the neanderthalised humans can serve as an origin for new RNA and DNA viruses as well as mutated retroviruses. The endosymbiotic archaea converts the Neanderthal cells to stem cells. The stem cells are resistant to immune attack. The stem cells can serve as a reservoir for this new RNA and DNA viruses. The stem cells and archaeal cells can also serve as a reservoir for viruses and bacteria belonging to other plants and animals. This helps to generate the species barrier jump in noted in recent emerging viral and bacterial infections. This paper studied the archaeal status in patients with recurrent viral infections and retroviral infections. The generation of RNA and DNA viroids from archaea was also studied. Materials and Methods: Blood samples were drawn from normal population, Neanderthal phenotype, retroviral infection and recurrent viral infection. There were 10 patients in each group and each patient had an age and sex matched healthy control selected randomly from the general population. The blood samples were drawn in the fasting state before treatment was initiated. Plasma from fasting heparinised blood was used and the experimental protocol was as follows (I) Plasma+phosphate buffered saline, (II) same as I+cholesterol substrate, (III) same as II+cerium 0.1 mg/ml, (IV) same as II+ciprofloxacine and doxycycline each in a concentration of 1 mg/ml. Cholesterol substrate was prepared as described by Richmond. Aliquots were withdrawn at zero time immediately after mixing and after incubation at 37oC for 1 hour. The following estimations were carried out:- Cytochrome F420, free RNA and free DNA. Cytochrome F420 was estimated flourimetrically (excitation wavelength 420 nm and emission wavelength 520 nm). Results: Plasma of Neanderthal phenotype showed increased levels of the above mentioned parameters with after incubation for 1 hour and addition of cholesterol substrate resulted in still further significant increase in these parameters. The plasma of retroviral patients and those with recurrent viral infections showed similar results but the extent of increase was insignificant. The addition of antibiotics to the control plasma caused a decrease in all the parameters while addition of cerium increased their levels. The addition of antibiotics to the patient’s plasma caused a decrease in all the parameters while addition of cerium increased their levels but the extent of change was more in Neanderthal phenotype sera as compared to patients with retroviral infection and recurrent viral infection. The results are expressed in tables 1-2 as percentage change in the parameters after 1 hour incubation as compared to the values at zero time. Discussion: The homo neanderthalis has archaea as endosymbionts. The archaea behaves like stem cells and can induce conversion of somatic cells to stem cells. The stem cells and archaeal cells can serve as reservoirs of other species virus and bacteria like plant and animal viruses and bacteria. The plant and animal viruses and bacteria can thrive in the somatic stem cells and archaeal cells as they escape immune detection. The Neanderthals tissue system can be compared to an archaeal/stem cell colony or network which serves as a reservoir for other animal and plant species bacteria and viruses as well as a generating centre for new RNA and DNA viruses. The RNA and DNA viruses are created by recombination between expressed genetically rearranged bits of the human chromosome and virus like DNA and RNA particles secreted by the archaea. This paves way for the generation of unlimited number of new RNA and DNA viruses as well as produce conditions for viruses and bacteria to cross the species barrier. This is evidenced by the SARS virus, the nipah virus and hendra virus crossing species. The algal virus has been reported to infect human brains producing cognitive dysfunction. The generation of new RNA and DNA viruses and the creation of a stem cell/archaeal reservoir for other species bacteria and viruses, the Neanderthal resistance to infections by viruses and bacteria and the Neanderthals serving as a reservoir for infection results in widespread pandemic in the homo sapien population in Africa and their eventual wipeout. Conclusion: Global warming depends on human endosymbiotic archaeal overgrowth and methanogenesis. The archaea can induce stem cell conversion, archaeal digoxin induced RNA editing, digoxin induced magnesium deficiency & reverse transcriptase inhibition and cholesterol catabolism induced CD4 receptor produces retroviral resistance. The archaeal secreted DNA and RNA viroids can recombine with the expressed retroviral, non-retroviral elements and other genomic segments of the human chromosome generating new RNA and DNA viruses. Thus the neanderthalised humans can serve as an origin for new RNA and DNA viruses as well as mutated retroviruses. The stem cells and archaeal cells can also serve as a reservoir for viruses and bacteria belonging to other plants and animals. This helps to generate the species barrier jump in noted in recent emerging viral and bacterial infections.

Rethinking hepatitis C viral kinetics: Insights into host-virus interactions in ‘difficult-to-treat’ groups and implications for novel treatment approaches

Chronic Hepatitis B Virus (HBV) infection remains a formidable global health challenge, driving severe liver complications such as hepatocellular carcinoma (HCC) and pyogenic liver abscesses (PLA). At the core of HBV persistence lies covalently closed circular DNA (cccDNA), a viral reservoir that fuels ongoing infection despite antiviral treatments. This review highlights molecular mechanisms governing cccDNA formation, maintenance, and clearance, spotlighting innovative therapeutic strategies to disrupt this key viral element. We explore cutting-edge approaches, including epigenetic modulation to silence cccDNA, RNA interference (RNAi) for viral RNA degradation, and CRISPR/Cas genome editing to excise cccDNA directly. Additionally, emerging antiviral therapies and immunotherapies, such as therapeutic vaccines and immune checkpoint inhibitors, offer new avenues for enhanced treatment efficacy. Special attention is given to the clinical complexities of managing HBV in patients with co-morbid conditions like HCC and PLA, emphasizing the necessity of a multidisciplinary approach. The interplay between antibacterial and antiviral therapies in PLA-associated HBV cases is critically examined to prevent treatment antagonism, ensuring optimal patient outcomes. Advanced therapeutic strategies, including nucleos(t)ide analogs, interferon therapy, and novel genomic interventions, are explored in both isolated HBV infection and PLA co-infections. Personalized regimens remain pivotal in enhancing therapeutic efficacy and long-term disease control. Current review advocates for a shift toward precision medicine, highlighting the critical need for interdisciplinary collaboration to bridge molecular discoveries with clinical innovations. Ultimately, these advancements promise to revolutionize the management of chronic HBV, paving the way for potential cures and improved patient outcomes.

Cellular viral reservoirs are rapidly established in tissues uponHIV-1/SIV infection, which persist throughout viral infection, even underlong-term antiretroviral therapy (ART). Specific integrins are involved in thehoming of cells to gut-associated lymphoid tissues (GALT) and inflamed tissues,which may promote seeding and dissemination of HIV-1/SIV to these tissue sites.In this study, we investigated the efficacy of prophylactic integrin blockade(α4β7 antibody or α4β7/α4β1 dualantagonist TR-14035) on viral infection, as well as dissemination and seeding ofviral reservoirs in systemic and lymphoid compartments post SIV inoculation. Theresults showed that blockade of α4β7/α4β1 did notdecrease viral infection, replication, or reduce viral reservoir size in tissuesof rhesus macaques after SIV infection, as indicated by equivalent levels ofplasma viremia and cell-associated SIV RNA/DNA to controls. Surprisingly,TR-14035 administration in acute SIV infection resulted in consistently higherviremia and more rapid disease progression. These findings suggest that integrinblockade alone fails to effectively control viral infection, replication,dissemination, and reservoir establishment in HIV-1/SIV infection. The use ofintegrin blockade for prevention or/and therapeutic strategies requires furtherinvestigation.

From infection to immune exhaustion: The Epstein-Barr virus and its contribution to Immunosenescence.

Hepatitis B, caused by the hepatitis B virus (HBV), often progresses to chronic infection, leading to severe complications, such as cirrhosis, liver failure, and hepatocellular carcinoma. Chronic HBV infection is characterized by a complex interplay between the virus and the host immune system, resulting in immune cell exhaustion, a phenomenon commonly observed in chronic viral infections and cancer. This state of exhaustion involves elevated levels of inhibitory molecules, cells, and cell surface receptors, as opposed to stimulatory counterparts. This review aims to elucidate the expression patterns of various co-inhibitory and co-stimulatory receptors on immune cells isolated from chronic hepatitis B (CHB) patients. By analyzing existing data, the review conducts comparisons between CHB patients and healthy adults, explores the differences between HBV-specific and total T cells in CHB patients, and examines variations between intrahepatic and peripheral immune cells in CHB patients. Understanding the mechanisms underlying immune exhaustion in CHB is crucial for developing novel immunotherapeutic approaches. This detailed analysis sheds light on the immune exhaustion observed in CHB and lays the groundwork for future combined immunotherapy strategies aimed at leveraging checkpoint receptors to restore immune function and improve clinical outcomes.

BackgroundAntiretroviral therapy (ART) partially corrects immune dysfunction associated with HIV infection. The levels of T-cell immune activation and exhaustion after long-term, suppressive ART and their correlation with CD4 T-cell count reconstitution among ART-treated patients in African cohorts have not been extensively evaluated.MethodsT-cell activation (CD38+HLA-DR+) and immune exhaustion (PD-1+) were measured in a prospective cohort of patients initiated on ART; 128 patient samples were evaluated and subcategorized by CD4 reconstitution after long-term suppressive treatment: Suboptimal [median CD4 count increase 129 (-43-199) cells/μl], N = 34 ], optimal [282 (200-415) cells/μl, N = 64] and super-optimal [528 (416-878) cells/μl, N = 30].ResultsBoth CD4+ and CD8 T-cell activation was significantly higher among suboptimal CD4 T-cell responders compared to super-optimal responders. In a multivariate model, CD4+CD38+HLADR+ T-cells were associated with suboptimal CD4 reconstitution [AOR, 5.7 (95% CI, 1.4-23, P = 0.014)]. T-cell exhaustion (CD4+PD1+ and CD8+PD1+) was higher among suboptimal relative to optimal (P < 0.001) and super-optimal responders (P < 0.001). T-cell exhaustion was significantly associated with suboptimal responders [AOR, 1.5 (95%CI, 1.1-2.1), P = 0.022].ConclusionT-cell activation and exhaustion persist among HIV-infected patients despite long-term, sustained HIV-RNA viral suppression. These immune abnormalities were associated with suboptimal CD4 reconstitution and their regulation may modify immune recovery among suboptimal responders to ART.

1. Jennifer A. Lowry, MD* 2. J. Steven Leeder, PharmD, PhD† 1. *Section of Clinical Toxicology, Division of Clinical Pharmacology, Toxicology and Therapeutic Innovations, Children’s Mercy Hospital, Department of Pediatrics, University of Missouri – School of Medicine, Kansas City, MO. 2. †Pediatric Clinical Pharmacology, Division of Clinical Pharmacology, Toxicology and Therapeutic Innovations, Children’s Mercy Hospital, Departments of Pediatrics and Pharmacology, University of Missouri-Kansas City, Kansas City, MO. Although there are benefits to the availability of over-the-counter products (eg, rapid access to effective medications, decreased utilization of the health care system, and patient autonomy), there also are risks to their use that clinicians should know and discuss with their patients and families. These include delay in seeking advice from a health care professional, increased drug-drug interactions, potential for misuse and abuse, and increased adverse effects when not used properly. After completing this article, readers should be able to: 1. Recognize that over-the-counter (OTC) cough and cold preparations have not been adequately studied in children younger than 6 years of age and that they are not recommended for treating the common cold. 2. Recognize the systemic effects of oral decongestants and antihistamines in infants and young children. 3. Recognize the signs and symptoms of acetaminophen and aspirin toxicity and know the management of overdose of these agents. 4. Be aware of potentially harmful additives in OTC medications. Over-the-counter (OTC) medications are widely marketed and frequently used to treat most health problems in adults and children. The use of symptomatic treatments, such as OTC medications for the common cold, is controversial. Children often receive analgesics, decongestants, antihistamines, expectorants, and cough suppressants during the course of their illnesses. However, these OTC products have not been proven to be safe and effective in young children. In addition, their common use puts children at risk for poisonings. Published data show no efficacy (no benefit) of OTC cough and cold preparations when compared to placebo for most ingredients in these products. After much review, the U.S. Food and Drug Administration (FDA) and the Consumer Healthcare Products Association issued …

In hepatitis B virus (HBV) infection, the immune reaction is responsible for viral clearance and preventing their spread within the host. However, the immune system is dysfunctional in patients with chronic HBV infection, leading to an inadequate immune response against the virus. A major factor contributing to inefficient immune function is the phenomenon of immune exhaustion. Hence, understanding immune activation and exhaustion during HBV infection is important, as it would provide insight in developing immunotherapy to control chronic HBV infection. The aim of this review is to highlight the existing information on immune effector functions and immune exhaustion in response to HBV infection.

Cardiopulmonary disease remains a leading cause of morbidity and mortality in HIV infection, despite widespread use of anti-retroviral therapies. Chronic inflammation due to ongoing viral replication may lead to immune exhaustion, a potential mechanism for the development of chronic obstructive pulmonary disease (COPD) and/or pulmonary arterial hypertension (PAH). Previously, we have shown that simian immunodeficiency virus (SIV) infection of macaques results in PAH and COPD. In the current study, we examined whether lymphocyte exhaustion and/or activation is associated with cardiopulmonary disease in SIV infection. Macaques were intravenously infected with SIVΔB670 (n=6, PAH study) or SHIV89.6P (n=11, COPD study). Blood and bronchoalveolar lavage (BAL) fluid cells from S(H)IV-infected animals were analyzed by flow cytometry. Serial pulmonary function testing and right heart catheterization were performed to assess pulmonary obstruction and mean pulmonary arterial pressure (mPAP), respectively. Increased effector memory CD8+ T (Tem) cells (CD95+CD28-) (p=0.008) and expression of programmed death-1 (PD-1), a marker of exhaustion (p&amp;lt;0.001), in the lung correlated with increased mPAP in SIV-infected macaques. Increased peripheral blood CD8+ Tem cells correlated with worse pulmonary function (p&amp;lt;0.001) in SHIV-infected macaques. These results support the hypothesis that HIV-related cardiopulmonary disease is associated with chronic immune activation and exhaustion.

Background: Mediators of immune exhaustion are an active area of breast cancer research. Type II diabetes mellitus (T2D), the most common metabolic disorder, both increases breast cancer incidence and decreases survival. Despite this clear link, impacts of the T2D immune phenotype on cancer remain poorly understood. We have previously demonstrated that the chronic inflammatory state of T2D leads to immune exhaustion, but how the T2D breast microenvironment interacts with T cells is unclear. Exosomes are crucial components of intercellular communication and are associated with increased breast cancer aggressiveness. Given this function, we hypothesized that T2D adipocyte-derived exosomes drive T cell exhaustion. Here, we characterize expression patterns and regulatory networks driving T2D immune phenotypes. Methods: Exosomes were first isolated from culture media of mature human primary breast adipocytes from, either insulin-sensitive (IS), or rendered insulin-resistant (IR) by ex vivo TNFα-treatment. Human primary peripheral blood mononuclear cells (PBMCs) from nondiabetic (ND) and T2D donors were stimulated ex vivo with plate bound anti-CD3 (5 ug/ml) and soluble CD28 (2 ug/ml) for 48 hours and treated with exosomes. Different small molecule inhibitors of the bromo and extraterminal (BET) protein family, including the pan-BET inhibitor JQ1 and the BRD4-selective PROTAC degrader MZ-1, were used to identify BET protein-regulated targets. We also used the AMP-activating protein kinase (AMPK) inhibitor Compound-C to identify the role of this pathway in activating this major epigenetic player. Multicolor flow cytometry was subsequently performed with an LSRII cytometer to assess expression of inhibitory receptors PD-1, CTLA-4, TIM-3 and TIGIT on immune subsets. Events for live cells were analyzed in FlowJo. Cytokines were collected from conditioned media and analyzed via Th17 cytokine staining panel. Results: We observed that exosomes derived from IR breast adipocytes increase expression of immune exhaustion markers in CD4+ and CD8+ T cells, compared to IS or ND matched controls. Additionally, we define signal transduction among BET proteins, AMPK signaling, and immune checkpoint expression. Lastly, we identify changes in cytokine profile between IS and IR treated groups. Taken together, our findings suggest a network of immune regulation imparted by exosomes. Impacts: Metabolic health does not inform the current standard of care in breast medical oncology, which contributes to a large, underserved population in which treatment plans are not well established or optimized for their comorbidities. Our findings offer a deeper understanding of immune checkpoint regulation in T2D and suggest new insights into treatment of diabetic breast cancer patients. Citation Format: Christina S. Ennis, Pablo LLevenes, Manohar Kolla, Naser Jafari, Anna C Belkina, Gerald V. Denis. Pathway analysis of immune checkpoint gene regulation as altered in Type 2 diabetes: Implications for breast cancer patients treated with checkpoint inhibitors [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-04-12.