Search Results (69)

Innate-like T cells (ILTCs) link innate immune responses with adaptive immune functions. This group includes invariant natural killer T (iNKT) cells, mucosa-associated invariant T (MAIT) cells, and γδ T cells. ILTCs detect transformed or stressed cells via non-classical antigen presentation pathways. For example, iNKT cells recognize CD1d-presented glycolipids, MAIT cells respond to MR1-presented metabolites from riboflavin pathways, and γδ T cells sense phosphoantigens through butyrophilin-dependent mechanisms and stress ligands. These features support early tumor control and shape downstream immunity by promoting dendritic cell activation, NK cell function, and priming of tumor-reactive CD8⁺ T cells. In established tumors, ILTC activity is frequently suppressed. Reduced antigen presentation, inhibitory cytokines, hypoxia, and metabolic constraints, including lactate accumulation and kynurenine production, limit effector responses and promote hyporesponsive states. Transcriptional regulators such as TOX, NR4A family members, and BATF are associated with these programs. This review discusses ILTC roles in tumor surveillance, immune escape, and therapeutic strategies to restore their function. Full article

Fibrosis is a hallmark of the tumor microenvironment in many solid cancers, driving tumor progression, immune evasion, and treatment resistance; however, the molecular and cellular mechanisms underlying fibrogenesis—particularly stromal–immune crosstalk across organs—remain incompletely understood, compounded by organ-specific heterogeneity and a lack of reliable immune-related biomarkers. To address this, we performed an integrative single-cell RNA sequencing (scRNA-seq) analysis of fibrotic tissues from four major organs—liver, lung, heart, and kidney—alongside non-fibrotic controls, applying unsupervised clustering, trajectory inference, cell–cell communication modeling, and gene set variation analysis (GSVA) to map the fibro-immune landscape. Our analysis revealed both conserved and organ-specific features: fibroblasts were the dominant extracellular matrix (ECM)-producing cells in liver and lung, whereas endothelial-derived stromal populations prevailed in heart and kidney. Immune profiling uncovered distinct infiltration patterns—macrophages displayed organ-specific polarization states; T cells were enriched for tissue-resident subsets in lung and mucosal-associated invariant T (MAIT) cells in liver; and B cells exhibited marked heterogeneity, including a pathogenic interferon-responsive subset prominent in pulmonary fibrosis. GSVA further identified divergent signaling programs across organs and lineages, including TGF-β/TNF-α in the heart, NOTCH/mTOR in the kidney, glycolysis/ROS in the lung, and KRAS/interferon pathways in the liver. Cell–cell communication analysis highlighted robust crosstalk between macrophages, T/B cells, and stromal cells mediated by collagen, laminin, and CXCL signaling axes. Together, this cross-organ atlas delineates a highly heterogeneous fibro-immune ecosystem in human fibrotic diseases, revealing shared mechanisms alongside organ-specific regulatory networks, with immediate translational implications for precision anti-fibrotic therapy, immunomodulatory drug repurposing, and the development of context-specific biomarkers for clinical stratification and therapeutic monitoring. Full article

Mucosal-associated invariant T (MAIT) cells exist in high numbers in the body and have a unique and highly conserved T cell receptor (TCR). They can be activated in a TCR-dependent manner by ligands presented on the monomorphic protein MHC class I-related protein 1 (MR1) which is found on many cell types, including professional antigen presenting cells (APCs) and epithelial cells. This has sparked interest in the potential to exploit the MR1-MAIT cell axis for the development of vaccines against infectious disease. Within this context an MR1 ligand, typically 5-(2-oxopropylideneamino)-d-ribitylaminouracil (5-OP-RU), is administered with or without a Toll-like receptor (TLR) ligand or cytokine in a pan vaccination approach that would prime the immune response to provide protection against a variety of bacterial and viral pathogens. This strategy has led to enhanced protection in murine models of Legionella longbeachae, Francisella tularensis, Klebsiella pneumoniae, Streptococcus pneumoniae and influenza infection. However, studies against Mycobacterium tuberculosis infection have proven less successful. The second vaccination approach involves pairing the MR1 ligand with more conventional antigens that could activate CD4⁺ and/or CD8⁺ T cells. This approach has been successful in murine models of cholera, influenza, and SARS-CoV-2, including in the context of subunit vaccines. However, there are several challenges when using MR1-MAIT cell-mediated vaccine adjuvants. These include the inherent instability of 5-OP-RU and the need for more advanced studies to better understand how the use of MR1 ligands would translate to applications in humans. This review will discuss these aspects and highlight the mechanistic studies that have been undertaken to understand how MAIT cells might elicit their effects within the context of MAIT cell-mediated vaccines for infectious disease. Full article

Innate-like T cells (iLTCs) are rapid sentinels at epithelial surfaces, yet their spatial organisation and tissue-linked programmes in psoriatic inflammation remain incompletely defined. Spatial transcriptomics from independent cohorts maps γδT and mucosal-associated invariant T cells (MAIT) niches across psoriatic skin and reveals sharply divergent skin-layer arrangements. Psoriatic plaques show expansion of both niches, with γδT transcriptional signatures present in dermis and epidermis and MAIT signatures strongly enriched in the epidermis. Their compartment-specific positioning is mirrored by distinct transcriptional activities that support dermal-sentinel behaviour for γδT-enriched niches and epithelial-retention programmes for MAIT niches. Clinical severity associates with opposite niche dynamics, marked by decreasing dermal γδT frequencies and increasing epidermal MAIT abundance. Functional profiles reinforce this divergence, as dermal γδT niches display rising exhaustion-associated features with greater severity, whereas epidermal MAIT niches show stronger inflammatory and proliferation-related signals. Peripheral CITE-seq profiling identifies parallel systemic patterns, with reduced γδT frequencies and increased MAIT frequencies in blood, along with exhaustion-associated features in γδT cells and MAIT-specific trafficking cues that align with their behaviour in psoriatic tissue. Together the findings define a spatially imbalanced γδT–MAIT axis in psoriatic inflammation that is linked to layer-specific organisation to local inflammatory cues, systemic immune engagement and clinical severity. Full article

Mucosal-associated invariant T (MAIT) cells are abundant innate-like T lymphocytes in the human liver which can provide antimicrobial defense, amplify inflammatory processes and mediate tissue repair and fibrosis depending on microenvironmental cues. Chronic liver diseases of diverse etiologies, including viral hepatitis, metabolic dysfunction-associated steatotic liver disease, alcohol-associated liver disease, biliary tract disease, autoimmune hepatitis and hepatocellular carcinoma are accompanied by numerical and functional adjustments in the MAIT cell population. In this review, we integrate existing data on MAIT cell markers and functions in diverse liver diseases, comparing how these cells are similarly or differentially shaped by distinct pathogenic contexts. Finally, we propose a spatially anchored conceptual and technical framework to study MAIT cell biology in liver disease. Full article

This review article attempts to provide a unifying hypothesis to explain the myriad of symptoms and predispositions underlying the development of PASC (Postacute Sequelae of COVID), often referred to as Long COVID. The hypothesis described here proposes that Long COVID is best understood as a disorder of persistent immune dysregulation, with chronic macrophage activation representing the fundamental underlying pathophysiology. Unlike transient post-viral syndromes, Long COVID involves a sustained innate immune response, particularly within monocyte-derived macrophages, driven by persistent spike protein (peripherally in MAIT cells and centrally in Microglial cells), epigenetic imprinting, and gut-related viral reservoirs. These macrophages are not merely activated temporarily but also become epigenetically “trained” into a prolonged inflammatory state, as demonstrated by enduring histone acetylation markers such as H3K27acDNA Reprogramming. It is proposed that recognizing macrophage activation as the central axis of Long COVID pathology offers a framework for personalized risk assessment, targeted intervention, and therapeutic recalibration. Full article

Chimeric antigen receptor (CAR)-based immunotherapy has emerged as a transformative strategy in anticancer treatment, driven by advances in CAR construct design, manufacturing platforms, and expansion to diverse immune cell types. The landmark success of CD19-targeted CAR-T cell therapy in B cell malignancies has paved the way for broader clinical applications. As of 2025, the U.S. FDA has approved multiple autologous CAR-T products, underscoring their therapeutic promise. However, challenges persist, including cytokine release syndrome (CRS), neurotoxicity, product inconsistency, and the high cost and complexity of cell manufacturing. Variations in cell source, gene delivery methods, expansion protocols, and CAR design significantly influence the safety, efficacy, and scalability of these therapies. In this review, we comprehensively examine the current advances in manufacturing protocols for CAR-modified T cells, natural killer (NK) cells, and unconventional T cell subsets, including γδ T, invariant natural killer T (iNKT), and mucosal-associated invariant T (MAIT) cells. We also highlight emerging innovations such as in vivo CAR-T generation and off-the-shelf allogeneic approaches. By integrating updated strategies with a critical evaluation of current limitations, this review aims to support the development of standardized, robust, and accessible CAR-based immunotherapies. Full article

Rheumatic heart disease (RHD) remains a major cause of preventable morbidity in low- and middle-income countries. As the most serious sequel of acute rheumatic fever (ARF) caused by Streptococcus pyogenes, RHD arises from molecular mimicry that drives autoimmune damage of cardiac valves. We systematically reviewed human studies (1977–2025) following PRISMA to clarify systemic immune signatures associated with valvular pathology. Searches of PubMed, LILACS, ScienceDirect, and Web of Science found 29 studies: 22 RHD and 7 ARF. In ARF, elevations in IL-6, IL-8, IL-17F, GM-CSF, TNF-a, and CXCL10 occurred alongside increased activity of CD4⁺ Th1 and MAIT cells. In RHD, a consistent inflammatory–fibrotic profile emerged with raised IL-17, IFN-γ, TNF-a, TGF-β1, Tenascin-C, and prothymosin alpha (ProTα) in blood and valve tissue. CD4⁺ and CD8⁺ T cells were implicated in valve injury; ProTα correlated with cytotoxic activity of circulating CD8⁺ T cells. Several mediators (IL-6, TNF-a, IL-8, CXCL10, CCL2, CCL19) were identified in RHD studies as being associated with inflammation, cell recruitment, and clinical severity. Systemic dysregulation mirrored local valve inflammation, suggesting circulating molecules may index ongoing cardiac damage. These findings underscore a central role for T cells and pro-inflammatory cytokines in RHD and highlight candidate prognostic markers and therapeutic targets to inform translational studies and trials. Full article

Conventional immunotherapy, including immune checkpoint blockade and chimeric antigen receptor (CAR)-T cells, has revolutionized cancer therapy over the past decade. Yet, the efficacy of these therapies is limited by tumor resistance, antigen escape mechanisms, poor persistence, and T-cell exhaustion, particularly in the treatment of solid tumors. The emergence of unconventional immunotherapies offers novel opportunities by leveraging diverse immune cell subsets and synthetic biologics. This review explores various immunotherapy platforms, including gamma delta T cells, invariant natural killer T cells, mucosal-associated invariant T cells, engineered regulatory T cells, and universal CAR platforms. Additionally, it expands on biologics, including bispecific and multispecific antibodies, cytokine fusions, agonists, and oncolytic viruses, showcasing their potential for modular engineering and off-the-shelf applicability. Distinct features of unconventional platforms include independence from the major histocompatibility complex (MHC), tissue-homing capabilities, stress ligand sensing, and the ability to bridge adaptive and innate immunity. Their compatibility with engineering approaches highlights their potential as scalable, efficient, and cost-effective therapies. To overcome translational challenges such as functional heterogeneity, immune exhaustion, tumor microenvironment-mediated suppression, and limited persistence, novel strategies will be discussed, including metabolic and epigenetic reprogramming, immune cloaking, gene editing, and the utilization of artificial intelligence for patient stratification. Ultimately, unconventional immunotherapies extend the therapeutic horizon of cancer immunotherapy by breaking barriers in solid tumor treatment and increasing accessibility. Continued investments in research for mechanistic insights and scalable manufacturing are key to unlocking their full clinical potential. Full article

Natural autoantibodies (nAAbs) recognize self-antigens and are an important component of the immune system, having evolved from invertebrates to vertebrates, and are viewed as stable byproducts of immune function and essential players in health and disease. Initially characterized by their conserved nature and multi-reactivity, primarily as IgM isotypes, nAAbs are now recognized for their adaptability in response to infections and vaccinations, bridging innate and adaptive immunity. The nAAbs and the cellular elements, such as γδ T, iNKT, and MAIT cells, of the natural immune system perform a primary defense network with moderate antigen-specificity. This comprehensive literature review was conducted to analyze the role of natural autoantibodies (nAAbs) in health and disease. The review focused on research published over the past 40 years, emphasizing studies related to infectious diseases, vaccinations, and autoimmune disorders. Recent studies suggest that nAAbs engage in complex interactions in autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, and type 1 diabetes. Their roles in immunological processes, such as maternal tolerance during pregnancy, further underscore their complexity. Emerging evidence indicates that nAAbs and the cellular elements of the natural immune system may contribute to both disease pathogenesis and protective mechanisms, highlighting their dual nature. Continued research on nAAbs is vital for improving our understanding of immune responses and developing therapeutic strategies for autoimmune disorders and infectious diseases. Full article

Unconventional T (UC T) cells, including invariant natural killer T (iNKT) cells, mucosal-associated invariant T (MAIT) cells, γδ T cells, and double-negative (DN) T cells, are key players in immune surveillance and response due to their properties combining innate-like and adaptive-like features. These cells are widely present in mucosal tissues, where they can rapidly respond to infections and tumor-associated changes. In fact, UC T cells can have both pro- and anti-tumoral effects, with their activity influenced by factors such as microbial composition and the tumor microenvironment. In particular, intratumoral microbiota significantly impacts the development, function, and activation of UC T cells, influencing cytokine production and shaping the immune response in various cancers. The complex crosstalk between UC T cells and the surrounding factors is discussed in this review, with a focus on how these cells might be interesting candidates to explore and exploit as anticancer therapeutic agents. However, the great potential of UC T cells, not only demonstrated in the context of adoptive cell transfer, but also enhanced through techniques of engineering, is still flanked by different challenges, like the immunosuppressive tumor microenvironment and heterogeneity of target molecules associated with some specific categories of tumors, like gastrointestinal cancers. Full article

Mucosal-Associated Invariant T (MAIT) cells, which bridge innate and adaptive immunity, have emerged as an important player in viral infections despite their inability to directly recognize viral antigens. This review provides a comprehensive analysis of MAIT cell responses across different viral infections, revealing consistent patterns in their behavior and function. We discuss the dynamics of MAIT cells during various viral infections, including changes in their frequency, activation status, and functional characteristics. Particular attention is given to emerging strategies for MAIT-cell-targeted vaccine development, including the use of MR1 ligands as mucosal adjuvants and the activation of MAIT cells through viral vectors and mRNA vaccines. Current knowledge of MAIT cell biology in viral infections provides promising approaches for harnessing their functions in vaccine development. Full article

Infection of hepatitis B (HBV) patients with hepatitis D (HDV) can cause the most severe form of viral hepatitis, leading to liver fibrosis, liver failure, and hepatocellular carcinoma. HDV relies on simultaneous infection with HBV for the generation of infectious viral particles. The innate immune response, which is weakly induced in HBV infection, becomes strongly activated upon HDV co-infection. In HBV/HDV co-infection, the immune system comprises a cell-intrinsic strong IFN response, which leads to the induction of interferon-stimulated genes (ISGs), the local activation of liver-resident innate immune cells, and additional immune cell recruitment from the blood. Efficient innate immune responses are indispensable for successful viral control and spontaneous viral clearance. Despite this fact, innate immune cell activation can also contribute to adaptive immune cell inhibition and accelerate liver damage in HBV/HDV infection. While the intrinsic IFN response in HDV-infected cells is well characterized, far less is known about the cellular innate immune cell compartment. In this review, we summarize HBV/HDV replication characteristics and decipher the role of innate immune cell subsets in the anti-viral response in HBV/HDV infections. We further review the impact of epigenetic and metabolic changes in infected heptatocytes on the innate anti-viral response. Moreover, we discuss the potential of exploiting the innate immune response for improving vaccination strategies and treatment options, which is also discussed in this review. Full article

The MHC class I-related 1 (MR1) molecule is a non-polymorphic antigen-presenting molecule that presents several metabolites to MR1-restricted T cells, including mucosal-associated invariant T (MAIT) cells. MR1 ligands bind to MR1 molecules by forming a Schiff base with the K43 residue of MR1, which induces the folding of MR1 and its reach to the cell surface. An antagonistic MR1 ligand, Ac-6-FP, and the K43A mutation of MR1 are known to inhibit the responses of MR1-restricted T cells. In this study, we analyzed MR1-restricted TCRs obtained from tumor-infiltrating lymphocytes (TILs) from breast cancer patients. They responded to two breast cancer cell lines independently from microbial infection and did not respond to other cancer cell lines or normal breast cells. Interestingly, the reactivity of these TCRs was not inhibited by Ac-6-FP, while it was attenuated by the K43A mutation of MR1. Our findings suggest the existence of a novel class of MR1-restricted TCRs whose antigen is expressed in some breast cancer cells and binds to MR1 depending on the K43 residue of MR1 but without being influenced by Ac-6-FP. This work provides new insight into the physiological roles of MR1 and MR1-restricted T cells. Full article

Mucosal-associated invariant T cells (MAIT cells) are a subset of T cells with innate, effector-like properties that play an essential role in the immune response to microbial infections. In humans, MAIT cells are detectable in the blood, liver, and lungs, but little is known about the frequency of these cells in the bone marrow. Also, the pathogenic role, if any, of MAIT cells in the development of aplastic anemia, a disease with an exquisite origin in the bone marrow, is currently unknown. We investigated the frequency and clinical relevance of bone marrow MAIT cells in a cohort of 14 patients (60.6 ± 23 and 57% women) with aplastic anemia. MAIT cells in the bone marrow samples obtained at diagnosis were evaluated by flow cytometry, and their association with various blood cell parameters and the patients’ clinical features was analyzed. MAIT cells were detectable in the bone marrow of all patients, with considerable variations among them. Bone marrow MAIT cells expressing the activator receptor natural killer group 2D - NKG2D (NKG2D+ MAIT cells) were significantly more abundant in the specimens of the aplastic anemia patients than in patients with bone marrow failure distinct from aplastic anemia. In addition, the NKG2D+ MAIT cells positively correlated with whole blood cell counts (WBC), platelet counts, and neutrophil counts, as well as with various inflammatory markers, including neutrophil-to-lymphocyte rate (NLR), platelet-to-lymphocyte rate (PLR), and systemic inflammatory index (SII). In functional studies, bone marrow CD34+ hematopoietic cells exposed to phytohemagglutinin or bacterial-derived lipopolysaccharide and acetyl-6-formylpterin upregulated MR1 (major histocompatibility complex, class I-related, known to interact with MAIT cells) and MICA/B (MHC class I chain-related gene A, a ligand of NKG2D) proteins on their cell surface, suggesting that under stress conditions, CD34+ hematopoietic cells are more likely to interact with NKG2D+ MAIT cells. In addition, NKG2D+ MAIT cells upregulated perforin and granzyme B in response to their interaction with recombinant MICA protein in vitro. This study reports for the first time the frequency of MAIT cells in the bone marrow of patients with aplastic anemia and assesses the potential implications of these cells in the pathogenesis or progression of aplastic anemia. Full article