Monocytes play crucial roles in the pathobiology of a wide range of medical conditions, including infection, autoimmunity, cardiovascular disease, and malignancies. Studies using flow cytometry revealed the complexity of monocyte biology, including identification of three human monocyte subsets: classical (CD14pos CD16neg), intermediate (CD14pos CD16pos) and non-classical (CD14neg/dim CD16pos) monocytes. Still, gating strategies used for identification of monocytes by flow cytometry vary substantially between studies, which may significantly impact results and hamper reproducibility. However, to our knowledge, no previous study has evaluated several different gating strategies for identification of the total circulating monocyte population in humans. Here, healthy donor peripheral blood mononuclear cells (PBMCs, n = 10) were analysed by flow cytometry to compare seven commonly used gating strategies for defining human monocytes: (1) negative selection (CD3neg CD19neg CD56neg CD66neg), (2) FSC-SSC, (3) CD14pos, (4) CD64pos, (5) HLA-DRpos, (6) CD14-HLA-DR and (7) TLR2pos. We show that the different gating strategies significantly impacted the enumeration of non-classical monocytes, but less so for classical and intermediate monocyte populations. Compared to negative selection gating (considered the reference standard), the FSC-SSC-based gating showed the highest degree of contamination by other cell types, whereas CD14pos, CD64pos, CD14-HLA-DR and HLA-DRpos gating showed highest degree of exclusion of monocytes, particularly non-classical monocytes. In comparison, TLR2pos gating showed both the least contamination and least erroneous exclusion of monocytes when compared to negative selection gating. These results based on 'manual gating' were supported by more objective t-SNE and clustering analyses. In conclusion, TLR2pos gating and negative selection-based gating displayed both minimal contamination and exclusion of true monocytes, with TLR2pos gating yielding the overall purest monocyte population. Thus, adapting to more uniform gating strategies for monocyte analysis, such as a TLR2 based gating strategy, may increase data quality and reproducibility between laboratories.
Plasmacytoid dendritic cells (PDCs) represent a crucial bridge between innate and adaptive immunity as they can recognise viruses and viral-infected cells, secrete type I interferon and prime naive T-cell responses. Like naive T cells, PDCs express CD62L, an essential molecule involved in the trans-endothelial migration process, and are supposed to travel directly from blood to lymph nodes to prime naive T cells. We developed a therapeutic PDC line model (PDC*line) derived from a patient with blastic PDC neoplasm, and showing high antigen-presentation capacities. PDC*line-based vaccine was tested in clinical trials in melanoma and lung cancer. Efficient specific T lymphocyte priming was observed suggesting the efficient migration of injected PDC*line-based vaccine to lymph nodes. Here, we investigated the mechanisms involved in this migration and its regulation. In humanised mice, our results demonstrated the efficient migration of the PDC-based vaccine from blood to lymph nodes and its capacity to prime naive T cells. The expression of CD62L was evaluated following irradiation, which was mandatory in the vaccine manufacturing step and possibly important for its efficacy. CD62L was rapidly shed after irradiation of PDC*line cells and primary PDCs but not of NK-T cells, demonstrating the cell specificity of the mechanism. Our results show that p38 MAP kinase, known to be activated in response to irradiation and ADAM17 metalloprotease are involved in the rapid CD62L shedding. This new pathway could participate to the regulation PDC transmigration through High Endothelial Venules and homing to secondary lymphoid organs in cellular stress conditions.
Despite significant advancements in the oncology field, lung cancer remains the leading cause of cancer-related mortality worldwide. A key contributor to the increased mortality rate is the resistance exhibited by cancer cells to standard anticancer treatments, particularly in advanced stages of the disease. Evidence indicates that chronic inflammation within the tumour microenvironment (TME) promotes tumorigenesis and contributes to resistance to immunotherapy, radiotherapy and chemotherapy. Notably, the overexpression of the cytokine interleukin-6 (IL-6) has been documented in various tumours, including lung cancer. Both tumour-associated fibroblasts (TAFs) and tumour cells constitute the predominant sources of secreted IL-6 within the TME. Various research has elucidated the role of IL-6 and its signalling pathways in facilitating therapeutic resistance, metastasis and tumour progression in lung cancer. Consequently, targeting IL-6 and/or its receptor, in conjunction with other effective anticancer treatments, represents an ideal therapeutic technique for lung cancer management. This review aims to synthesize recent evidence on the function of the IL-6/IL-6R signalling pathway in lung cancer, with a focus on its role in therapy resistance, prognosis and tumour progression, on the basis of clinical and preclinical studies.
Acute ischemic stroke is accompanied by marked peripheral and central immune imbalance, in which disruption of the Th17/Treg axis is considered an important driver of aggravated neuroinflammation and secondary injury, yet the upstream regulatory pathways amenable to intervention remain unclear. We hypothesised that the probiotic Akkermansia muciniphila (AKK) could be linked to post-stroke immune remodelling and neuroprotection by influencing intestinal epithelial signalling. Using a tMCAO mouse model combined with AKK intervention, SIRT1 inhibition, IL-17-deficient conditions, and IL-17 neutralisation/rescue experiments, we systematically assessed intestinal barrier integrity, peripheral and central immune responses, and neurological injury, together with single-cell transcriptomic and ATAC-seq analyses of the Th17/Treg axis. Complementary human and murine intestinal epithelial-T cell co-culture systems and a neuronal OGD model were used for functional mechanistic assessment. AKK was associated with activation of AMPK/SIRT1 signalling, decreased Th17 proportions, increased Treg levels, suppression of IL-17-associated inflammatory responses, and enhancement of IL-10 signalling, thereby improving systemic and intracerebral inflammatory environments. In the neuronal OGD model, IL-17 neutralisation alone provided partial protection, combined AKK and IL-17 blockade further enhanced neuroprotection, and recombinant IL-17 rescue attenuated, but did not fully define, the protective effects of AKK. AKK also protected intestinal barrier integrity, reduced infarct volume, and improved neurological function. Together, these findings support a contributory gut epithelial AMPK/SIRT1-associated immunoregulatory network in which AKK is linked to Th17/Treg immune remodelling and reduced post-stroke neuroinflammation through the gut-immune-brain axis, while IL-17 signalling appears to represent one important component rather than an exclusive pathway.
Peripheral T cell profiles reflect antitumour immunity, yet systemic immune shifts often remain confounded by demographic factors. This study aimed to delineate true tumour-driven T cell alterations in lung cancer. We analysed peripheral blood from 121 lung cancer patients and strictly age- and sex-matched healthy controls using multiparametric flow cytometry, corroborated by human lung cancer spatial transcriptomics (ST). Following demographic standardisation, patients exhibited a systemic T cell priming blockade, characterised by significantly accumulated naïve T cells and depleted effector memory T cells (CD4+ p < 0.01; CD8+ p < 0.0001). Conversely, Th17.1 cells and immune checkpoints (e.g., PD-1, CTLA-4) were robustly elevated. Crucially, ST validated a striking intratumoural spatial accumulation of Th17.1 cells. We conclude that the peripheral expansion of Th17.1 cells is a genuine tumour-driven event that faithfully mirrors local tumour microenvironment remodelling and potential Tertiary Lymphoid Structure (TLS) neogenesis. This positions peripheral Th17.1 profiling as a valuable, noninvasive biomarker for evaluating systemic immunosuppression and guiding personalised immunotherapy.
Transmembrane activator and calcium-modulator and cyclophilin-ligand interactor (TACI), encoded by TNFRSF13B, plays a central role in B cell maturation and antibody responses through its interactions with BAFF and APRIL, with variants being linked to common variable immunodeficiency (CVID) and selective IgA deficiency. To characterise the clinical, immunological and genetic spectrum of these individuals, we recruited 30 participants (21 patients and nine family members) and classified patients into Group 1 (n = 16), carrying only TACI variants and Group 2 (n = 5), carrying both an IEI-related variant and an additional TACI variant. With a male/female ratio of 12/9, the median age was 2 years at symptom onset and 14 years at genetic diagnosis. Common clinical manifestations included recurrent infections (90%), autoimmune/inflammatory features (62%) and lymphoproliferation (57%). Twelve distinct TNFRSF13B mutations were identified, predominantly clustering in the cysteine-rich domain 2 (CRD2), with Cys104Arg being the most frequent (57%) variant. Immunophenotyping revealed decreased switched-memory and marginal zone B cells, reduced naïve CD4+ T cells and increased effector memory subsets. Notably, clinical and laboratory features overlapped between Groups 1 and 2, as well as between monoallelic and biallelic TNFRSF13B variant carriers. Patients with TNFRSF13B variants display broad phenotypic heterogeneity ranging from asymptomatic carriage to CVID and combined immunodeficiency phenotypes. Given the high polymorphism ratio and incomplete penetrance observed, TACI acts as both a genetic modifier and a monogenic disease-causing gene in this cohort, suggesting that coexisting genetic variants and exposomal factors likely determine the clinical expression and disease severity.
Traditionally considered immune-privileged, the central nervous system (CNS) is now recognised as immunologically dynamic, with the meninges serving as a key interface for immune surveillance and neuroimmune communication. Recent advances support the emerging concept of a gut-meningeal immune axis, wherein the gut microbiota may influence meningeal immunity, through the recruitment of gut-educated immune cells and other microbiota-dependent signals, although the mechanisms involved remain incompletely understood. Notably, the neonatal period represents a critical window of immune and microbial development, during which dysbiosis can disrupt microglia maturation, cytokine balance, and long-term neuroimmune resilience. Here, we review the structural and immunological properties of the meninges, the mechanisms potentially linking the gut microbiota to meningeal immunity, and the role of this emerging axis in neuroinflammatory diseases. We further explore the developmental implications of early-life microbial disturbances and discuss the therapeutic potential of microbiota-targeted interventions to modulate meningeal immunity and mitigate CNS pathology.
Autoimmune and autoinflammatory diseases are characterised by dysregulated immune activation and persistent inflammation, yet effective mechanism-based therapeutic targets remain limited. Proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2), a membrane-cytoskeleton-associated adaptor protein predominantly expressed in myeloid cells, has emerged as an important endogenous regulator of inflammatory responses. This review summarises the molecular structure, expression pattern and biological functions of PSTPIP2, with particular emphasis on its role in coordinating cytoskeletal remodelling, inflammatory signalling and immune-cell behaviour. We further discuss the major mechanisms through which PSTPIP2 regulates disease progression, including suppression of IL-1β maturation, inhibition of NF-κB and ERK signalling, modulation of macrophage polarisation and control of osteoclast-associated bone remodelling. In addition, recent advances in understanding the involvement of PSTPIP2 in chronic multifocal osteomyelitis, rheumatoid arthritis, SAPHO syndrome and bullous pemphigoid are reviewed, together with evidence from PSTPIP2-deficient models that has provided important mechanistic and translational insights. Finally, the potential value of PSTPIP2 as a biomarker and therapeutic target is highlighted. Overall, PSTPIP2 represents a critical immunoregulatory node linking cytoskeletal organisation to inflammatory control, and further investigation of its molecular functions may facilitate the development of precision therapies for autoimmune and autoinflammatory diseases.
Clostridioides difficile infection (CDI) remains a major cause of antibiotic-associated colitis and is characterized by excessive intestinal inflammation, epithelial barrier disruption and impaired mucosal repair. Although sodium butyrate (NaB), a microbiota-derived short-chain fatty acid, has demonstrated anti-inflammatory and barrier-protective properties, the immunological mechanisms underlying its protective effects during CDI remain incompletely understood. In this study, we investigated the role of NaB in regulating macrophage polarization and epithelial repair using murine CDI models, primary bone marrow-derived macrophages, THP-1-derived macrophages, Caco-2 epithelial cells and macrophage-epithelial co-culture systems. NaB treatment significantly alleviated CDI-associated weight loss, colonic shortening, histopathological injury and inflammatory cytokine production while restoring epithelial barrier integrity and tight junction protein expression. Mechanistically, NaB promoted macrophage polarization towards an anti-inflammatory M2 phenotype, characterized by increased CD206 and IL-10 expression and reduced CD86 and IL-1β expression. These immunomodulatory effects were accompanied by suppression of PI3K/Akt/mTOR signalling in both colonic tissues and macrophages. Pharmacological inhibition and activation studies further supported the involvement of this pathway in NaB-mediated macrophage reprogramming. Importantly, conditioned medium from NaB-treated macrophages enhanced epithelial viability, migration and barrier-associated protein expression, whereas IL-10 neutralization partially abolished these protective effects, highlighting a critical role for macrophage-epithelial crosstalk. Collectively, our findings demonstrate that low-dose NaB protects against CDI-induced intestinal injury through coordinated regulation of macrophage polarization and epithelial barrier repair, at least in part via modulation of PI3K/Akt/mTOR signalling. These results identify NaB as a promising host-directed therapeutic strategy for CDI and provide new insights into microbiota-derived metabolite-immune interactions during intestinal inflammation.
Tumour immune evasion frequently involves PD-L1-mediated inhibition of T cell activity, limiting the efficacy of PD1/PD-L1 blockade, particularly in PD-L1-low or immunologically 'cold' tumours. To overcome this limitation, we developed a dual targeting human PD1-CD137L (hPD1-CD137L) fusion protein that blocks PD-L1-PD1 inhibitory signalling and simultaneously delivers CD137-mediated T cell costimulation. The fusion protein was produced with high purity and demonstrated specific binding to PD-L1-expressing tumour cells and CD137-positive T cells. The hPD1-CD137L retained a stable multimeric structure under acidic conditions and during prolonged storage, supporting its suitability for systemic administration and activity within the tumour microenvironment. Functionally, hPD1-CD137L enhanced T cell activation, as evidenced by increased NF-κB signalling and activation marker expression, and promoted robust tumour cell cytolysis in both 2D and 3D co-culture systems. Anti-tumour activity was observed across multiple tumour models with varying PD-L1 expression, including nasopharyngeal carcinoma (NPC), rhabdomyosarcoma, lung carcinoma and patient-derived colorectal cancer organoids. Notably, hPD1-CD137L enhanced cytolysis of C666 NPC cells by patient-derived tumour-infiltrating lymphocytes at low effector-to-target ratios, and was more potent than a combination of an anti-PD-1 antibody and a CD137 agonist. In vivo, PBMC-humanised NSG mice tolerated hPD1-CD137L without significant weight loss, systemic inflammation or survival impact. Subsequent efficacy study in PBMC-humanised, Rd18 rhabdomyosarcoma-engrafted or C666 nasopharyngeal carcinoma-engrafted NSG mice showed tumour growth suppression without overt toxicity. This study validates a human PD1-CD137L fusion protein as a potent drug candidate for cancer immunotherapy.
Myo1g, a short-tail class I myosin, has been extensively studied for its roles in cellular adhesion, migration, cytokine secretion and receptor recycling in T and B lymphocytes. However, its involvement in other immune cell populations, particularly natural killer (NK) cells, remains an open question in immunology. NKR-P1C is a type II integral membrane glycoprotein with a C-type lectin domain; it also plays roles in NK cell activation and differentiation, IFN-γ production, cytotoxic granule release. The expression of Myo1f and Myo1g mRNA in NK cells was previously found in the RIKEN database (https://gexc.riken.jp/). Thus, the present study began by confirming the presence of Myo1g protein in lysates from splenic NK cells of wild-type (WT) mice. Subsequently, it was found that mice deficient in Myo1g (Myo1g-/-) exhibited decreased frequency and absolute numbers of NK cells (defined as CD3-, CD19- and NKR-P1C+ lymphocytes) in the bone marrow, blood and spleen. Then, NK cell development was evaluated (CD122, CD49b and NKp46), demonstrating that the absence of Myo1g does not affect overall NK cell generation but does influence NKR-P1C expression. A functional analysis revealed reduced degranulation in NK cells from Myo1g-/- mice compared to WT controls. These findings were corroborated using purified NK cells, which demonstrated that NK cells from Myo1g-/- deficient mice exhibit reduced cytotoxicity. Collectively, these results suggest that Myo1g may serve as a potential target for modulating NK cell function and immune responses. To hypothesize potential mechanisms linking Myo1g to NKR-P1C expression and cytotoxicity, it is possible that Myo1g influences the stability or surface trafficking of NKR-P1C, given its known role in receptor recycling. Additionally, the absence of Myo1g could impair the cytoskeletal reorganisation required for NK cell function, affecting the formation of immunological synapses and the subsequent degranulation process.
The myeloid differentiation primary response protein 88 (MyD88) family of Toll/interleukin-1 receptor (TIR) domain-containing adaptor proteins constitutes a central signalling hub that integrates innate immune sensing with tissue-specific stress responses. This family comprises five mammalian members: MyD88, TIRAP/MAL, TRIF/TICAM-1, TRAM/TICAM-2 and SARM1 (also known as MyD88-1 through MyD88-5). While these adaptors are classically defined by their roles in immune and haematopoietic cells, accumulating genetic and mechanistic evidence demonstrates critical, cell-intrinsic functions in non-immune tissues. Canonical MyD88 signalling assembles IRAK-containing complexes to activate NF-κB and MAPK pathways, whereas TIRAP and TRAM function as sorting adaptors that impose spatial and receptor specificity. TRIF mediates MyD88-independent interferon programs downstream of Toll-like receptor (TLR)-3 and internalised TLR-4. Beyond immunity, MyD88-family signalling regulates epithelial barrier integrity, hepatic metabolic homeostasis, skeletal muscle metabolism and atrophy, endothelial permeability, renal injury responses and neuronal degeneration. Notably, SARM1 represents a functionally divergent family member whose TIR domain acts as an intrinsic NAD+ hydrolase driving axonal degeneration. Here, we synthesise structural, genetic and cell-specific studies to highlight how compartmentalised adaptor usage and domain-specific mechanisms generate context-dependent signalling outcomes across immune and non-immune tissues. These insights redefine MyD88-family adaptors as modular regulators of tissue physiology and disease, with implications for targeted therapeutic intervention.
Metabolism is critical for immune cell functions. Tumours shape their microenvironment to render it metabolically hostile for infiltrating immune cells. While targeting immunometabolism emerges as a promising way to reinvigorate anticancer immunity, a deeper understanding of the metabolic disturbances of immune cells is needed. Here, we explored how the metabolic status of T cells governs immune skewing from circulating and tumour-infiltrating CD4+ and CD8+ T cells of melanoma patients at a single-cell level using the SCENITH method and targeted metabolomics. Circulating and tumour-infiltrating T cells from patients displayed a decreased mitochondrial dependency associated with an enhanced glycolytic capacity and a skewed metabolic reprogramming upon stimulation. Such metabolic disturbances were linked to the activation status, immune checkpoint profile and functional orientation of T cells, underlining critical connections between T-cell features and metabolic patterns. Targeted metabolomics within sorted CD4+/CD8+ T cells identified a decrease in citrulline, cysteine and threonine within all subsets in patients, together with a sharp rise in sterol cholesterol CE(20:2) and ceramide dhCer(d18:0/22:0) within tumour-infiltrating CD4+ T cells, and in glycerolipid DG(16:0/16:0) within CD8+ T cells in blood and tumour. We further outlined a metabolic-checkpoint-based signature composed of six genes coding enzymes/transporters connected to the imbalanced metabolites found within tumour-infiltrating T cells (LIPA, DGKA, GLUL, SLC38A1, SLC7A7, GCH1) that shape patients' clinical outcome. These findings outline the skewed bioenergetic profiles of T cells and depict metabolic checkpoints associated with immune subversion. Harnessing metabolic pathways is promising for developing innovative therapies to restore optimal anti-tumour responses and improve clinical success.
Type 2 immunity at mucosal surfaces is essential for helminth clearance, tissue repair, and barrier maintenance, processes governed by a robust feed-forward circuit between chemosensory tuft cells and group 2 innate lymphoid cells (ILC2s). However, the regulatory mechanisms that calibrate the magnitude and duration of this epithelial immune circuit remain incompletely defined. Here, we identify interleukin-18 (IL-18), a cytokine traditionally associated with type 1 immunity, as a key regulator of tuft cell-mediated type 2 responses during Nippostrongylus brasiliensis (N. brasiliensis) infection. IL-18-deficient (Il18-/-) mice exhibited reduced intestinal worm burden at day 7 post-infection, which correlated with an expansion of tuft cell lineage, increased expression of tuft cell and type 2 response associated genes, and enhanced ILC2 responses. Consistent with these findings, loss of IL-18 receptor (Il18r1-/-) further enhanced succinate-induced tuft cell hyperplasia. Within the intestinal epithelium, tuft cells were found to preferentially express IL-18Rα, suggesting potentially direct responsiveness to IL-18. Using small intestinal organoid models, we demonstrate that IL-18 directly attenuates IL-13-induced tuft cell differentiation, proliferation, and signature gene expression in an IL-18Rα-dependent manner. Mechanistically, pharmacological inhibition of p38 MAPK partially reversed the inhibitory effects of IL-18, identifying p38 signalling as a critical downstream mediator of this regulatory process. Together, these findings reveal that IL-18 functions as a negative feedback signal to constrain tuft cell-associated type 2 epithelial responses during helminth infection, thereby maintaining the balance between protective anti-helminth immunity and mucosal homeostasis.
The gut microbiota functions as a metabolically active microbial ecosystem that engages in bidirectional communication with the host nervous and immune systems, thereby contributing to homeostasis and disease pathogenesis. Eosinophil extracellular traps (EETs)-web-like structures composed of DNA and granule proteins released by activated eosinophils-exert context-dependent roles in host defence and immune regulation, with both pro-inflammatory and anti-inflammatory effects. Their function in tumour immunity, however, remains controversial. This review summarizes recent advances in understanding how the gut microbiota regulates eosinophil function and EET formation through the neuroimmune axis, encompassing the vagus nerve, neurotransmitters, and neuropeptides. We focus on the role of this regulatory network within the tumour microenvironment and discuss its potential influence on the efficacy of immune checkpoint inhibitors and the development of immune-related adverse events. By integrating evidence across microbial metabolism, neural signalling, and eosinophil biology, we aim to delineate the molecular mechanisms underlying this multilevel network and to provide a theoretical framework for anti-tumour strategies that co-target the gut microbiota and the neuroimmune axis, with the goal of improving immunotherapy outcomes while limiting treatment-related toxicity.
Metabolic Syndrome (MetS) is characterized by a set of clinical conditions that elevate cardiovascular risk and may interfere in several pathways of the immune system, as well as the medications used for its treatment. The aim of this study was to evaluate antigen-specific and polyclonal cellular immune responses in patients with MetS. Thirty-two participants were divided into three groups: individuals with MetS in use of medication for metabolic conditions (MST), individuals with MetS without treatment (MS), and healthy donors (HD). Blood samples were collected, and peripheral blood mononuclear cells were obtained and stimulated in vitro with peptide pools to evaluate antigen-specific and polyclonal responses. Supernatants were collected for quantification of interleukin-2 (IL-2), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10). Intragroup comparisons revealed that the MS group showed a more diverse cytokine production compared to the other groups after antigen-specific stimulation, that could represent a more vigorous immune activation. The comparison of groups revealed that the MST group produced lower levels of IL-2 and IL-10 than HD and lower levels of TNF-α than the MS group after polyclonal stimulation. This attenuated response in the MST group may have multiple causes, such as the inhibitory effects of hyperglycemia on cytokines production and/or the use of medication for metabolic conditions that may exhibit anti-inflammatory effects. Therefore, the MS group demonstrated a broader cytokine production profile after antigen-specific stimulation, whereas the MST group exhibited quantitatively lower cytokine production in response to polyclonal stimulation. The implications of these findings require further investigation.
Chronic inflammatory and autoimmune diseases are characterised by dysregulated Th1 and Th17 immune responses, leading to excessive production of proinflammatory cytokines. Shikonin (SK) is a natural anti-inflammatory compound whose therapeutic use is limited by poor solubility and bioavailability. Here, we evaluated SK-loaded hyaluronic acid-zein (HA-Zein) nanogels as a targeted strategy to modulate inflammatory CD4+ T-cell responses in vitro and in vivo. HA-Zein nanogels were designed to preferentially target CD44+ activated/effector T cells, key mediators of inflammation in Th1- or Th17-associated diseases. SK-HA-Zein nanogels preferentially interacted with CD44+ activated CD4+ T cells and reduced IFN-γ production and Th1-associated polarisation while preserving Th17-associated readouts. At higher concentrations, SK enhanced FoxP3/IL-10-associated regulatory features. Metabolomic analysis revealed that SK-HA-Zein nanogels inhibited key metabolic activities of Th1 cells, including glutamine and glucose consumption, thereby reducing overall cellular activity. In an acute in vivo inflammation model, SK-HA-Zein nanogels reduced local IFN-γ levels and inflammatory cell infiltration. These findings support SK-HA-Zein nanogels as a targeted immunometabolic strategy to dampen inflammatory CD4+ T-cell responses and promote regulatory features in chronic inflammatory settings.
Medullary thymic epithelial cells (mTECs) are central to immune self-tolerance owing to their capacity to express and present a diverse repertoire of self-derived peptides to developing thymocytes. This diversity arises from both promiscuous gene expression and specialised differentiation programmes, including thymic mimetic-cell populations, and is largely shaped by AIRE/Aire and FEZF2/Fezf2. Although the roles of Aire and Fezf2 in regulating peripheral tissue antigen transcription are well established, a critical conceptual gap remains regarding how transcriptional promiscuity is translated into the repertoire of peptides presented by major histocompatibility complex class II (MHC-II) molecules. In this review and perspective, we synthesize knowledge on mTEC biology, Aire- and Fezf2-dependent transcriptional programmes, and advances in immunopeptidomics. We discuss regulatory layers that decouple mRNA abundance from peptide presentation and highlight how single-cell transcriptomics and mass spectrometry-based immunopeptidomics provide complementary insights into mTEC heterogeneity and antigenic output. We argue that integrating these approaches is essential to understand central tolerance mechanistically and to explain selective defects in thymic self-antigen presentation. This framework offers a refined basis for interpreting autoimmune disease origins and guiding antigen-focused therapeutic strategies.
ABSTRACT Chimeric antigen receptor T (CAR‐T) cell therapy has transformed the treatment of relapsed or refractory haematologic malignancies, but immune effector cell‐associated neurotoxicity syndrome (ICANS) remains a major and potentially life‐threatening complication. Although most patients with ICANS improve after standard corticosteroid therapy, a subset shows insufficient improvement or neurological deterioration after corticosteroid initiation, a clinical scenario often described as corticosteroid‐refractory or steroid‐refractory ICANS. ICANS develops through a cascade initiated by CAR‐T cell expansion and systemic cytokine release, followed by endothelial activation, blood–brain barrier disruption, glial‐driven neuroinflammation, and neuronal injury. This process may be further amplified by on‐target off‐tumour effects and extracellular vesicles released from CAR‐T cells. ICANS risk is influenced by CAR construct design, target antigen, and disease context. Several tools may contribute to multimodal risk assessment, including the Immune Effector Cell‐Associated Encephalopathy (ICE) score, EASIX/m‐EASIX, ICANS‐PSS, CART‐NS, cytokine profiles, neurofilament light chain, electroencephalography, and imaging, although their predictive value requires further validation. This review summarises the cytokine‐mediated mechanisms, product‐specific risk patterns, and early recognition strategies of ICANS after CAR‐T cell therapy. It also critically appraises emerging investigational approaches for corticosteroid‐refractory ICANS, including cytokine‐directed interventions, endothelial‐stabilising strategies, tyrosine kinase inhibition, CAR‐T cell depletion, intrathecal therapy, and engineered suicide gene systems.
Psoriatic disease is characterised by persistent immune activation that is closely linked to tissue context and clinical severity. How immune metabolism is organised within inflamed skin and across systemic immune compartments remains incompletely elucidated. Here, spatial transcriptomics and CITE-seq datasets were analysed to characterise immune metabolic niche organisation across skin and circulation. Two metabolic constraint axes capturing oxygen redox and nutrient limitation were used to define metabolically constrained and permissive immune niches within leukocyte-rich tissue regions and circulating immune lineages. Psoriatic lesions exhibited a pronounced shift towards metabolically constrained immune niches that distinguished psoriasis from atopic dermatitis. This imbalance showed strong spatial organisation, with dominance within the epidermis and close alignment with immune activation programmes. Epidermal metabolic organisation scaled with clinical severity and was accompanied by increased immune activation in severely affected tissue, while dermal organisation remained comparatively stable. Extending these observations to circulation, immune metabolic states were further skewed towards constraint in psoriatic patients with joint involvement, consistent with higher systemic inflammatory burden, with prominent effects observed in CD4 T cells. Together, these findings identify immune metabolic niche organisation as a spatially and systemically structured feature of psoriatic disease that links tissue architecture, immune activation and clinical severity.
