Engineered Treg cells as putative therapeutics against inflammatory diseases and beyond

Exploiting regulatory T cells (Tregs): Cutting-edge therapy for autoimmune diseases

Regulatory T cells (Tregs) are a specialized subset of suppressive T cells that are essential for maintaining self-tolerance, regulating effector T cells, managing microbial infections, preventing tumors, allergies, and autoimmune disorders, and facilitating allograft transplantation. Disruptions in Treg function or abundance contribute to an imbalance between pathogenic and protective immune cells in autoimmune diseases. Recently, one promising treatment strategy to restore immune balance involves the selective expansion or manipulation of Tregs using low-dose IL-2 therapy, adoptive Treg cell transfer, and chimeric antigen receptor (CAR)-Treg approaches. Tregs have been shown in an increasing number of research studies to prevent or even treat a variety of disorders, such as tumors, autoimmune and allergic diseases, transplant rejection, and graft-versus-host disease. A thorough comprehension of Treg function is anticipated to provide clear prospects for effective Treg immunotherapy in the treatment of a wide range of diseases. This review provides an overview of Tregs biology, including their functions, suppressive mechanisms, phenotypic markers, as well as their involvement in disease settings. Furthermore, we discuss the therapeutic potential of different Treg subpopulations and their translational applications in the treatment of autoimmune diseases.

Adoptive transfer of regulatory T cells inhibits the progression of endometriosis-like lesions in regulatory T-cell-depleted mice

STUDY QUESTION

Does the restoration of regulatory T cells (Tregs) suppress the progression of endometriosis?

SUMMARY ANSWER

Adoptive transfer of Tregs suppresses the progression of endometriosis and reduces the levels of helper T (Th)-cell-related and proinflammatory cytokines in mice.

WHAT IS KNOWN ALREADY

Endometriosis is a chronic inflammatory gynecological disease, which involves multiple immune components. Activated Treg counts decrease in the endometrioma and endometrium of patients with endometriosis, and depletion of Tregs exacerbates endometriosis in mice.

STUDY DESIGN, SIZE, DURATION

We evaluated the effects of adoptive transfer of Tregs on the progression of endometriosis in mice. We used Foxp3tm3Ayr/J (Foxp3DTR) mice with temporarily ablated Tregs by injecting diphtheria toxin to develop an endometriosis model, which was generated by ovariectomy, estradiol administration and transplantation of uterine fragments from donor mice. Foxp3DTR mice were randomly divided into Treg adoptive transfer (n = 12) and control (n = 11) groups. Tregs were isolated from lymph nodes and spleens of wild-type (WT) mice and were adoptively transferred into mice that were temporarily Treg-depleted. Control mice were injected with vehicle. Treg adoptive transfer was performed on the day of uterine implantation, and a second adoptive transfer was performed after 14 days. Mice were euthanized 28 days after uterine implantation, and blood, peritoneal fluid, spleen, and endometriosis-like lesion samples were collected.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Foxp3DTR mice were intravenously injected with Tregs isolated from WT mice. The number, total weight, and total volume of the endometriosis-like lesions were evaluated on Day 28 following implantation of uterine fragments. The proportion of Tregs in endometriosis-like lesions, ascites, and peripheral blood was analyzed by flow cytometry. Inflammation in lesions and serum was examined using real-time PCR and ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Injection of Tregs increased their total count and decreased the number (P < 0.0001), weight (P = 0.0021), and volume (P = 0.0010) of endometriosis-like lesions in Foxp3DTR Treg-depleted mice. Furthermore, injection of Tregs decreased the mRNA expression of Th 1-, 2-, and 17-related cytokines, including interferon gamma (P = 0.0101), interleukin (IL)-4 (P = 0.0051), and IL-17 (P = 0.0177), as well as the levels of the proinflammatory cytokine IL-6 (P = 0.0002), in endometriosis-like lesions of Foxp3DTR Treg-depleted mice.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Treg-related immune mechanisms in mice may not precisely reflect those in humans.

WIDER IMPLICATIONS OF THE FINDINGS

Restoration of Tregs may be a useful therapeutic strategy for inhibiting the progression of endometriosis in cases where the decrease in the Treg population is an exacerbating factor.

STUDY FUNDING/COMPETING INTEREST(S)

This study was partially supported by the Grants-in-Aid for Scientific Research (grant numbers 18K16808 and 20K22983) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. The sponsor had no role in the study design, collection, analysis and interpretation of data, writing of the report, and decision to submit the article for publication. The authors have no conflicts of interest to disclose.

Oxytocin-Mediate Modulation of Splenic Immunosuppression in Chronic Social Stress Through Neuroendocrine Pathways

Chronic social stress (CSS) is a significant public health challenge that negatively impacts behavior and immune function through brain-spleen interactions. Oxytocin (OT), a neuropeptide critical for social behavior and immune regulation, is upregulated during CSS, though its underlying mechanisms remain unclear. This study investigates the role of OT in splenic immune modulation using a murine model of CSS. Behavioral evaluations, serum oxytocin quantification, and splenic immunophenotypic analysis were performed. Splenic denervation confirmed OT's neuromodulatory role, whereas OTR antagonism revealed its endocrine function. CSS-induced OT elevation was associated with immunosuppression, characterized by increased Foxp3⁺ regulatory T cells and reduced CD4⁺ T and CD19⁺ B cells. OT also modulated macrophage polarization, inhibiting M1-like (pro-inflammatory) and enhancing M2-like (anti-inflammatory) phenotypes. Denervation or pharmacological blockade of OT signaling partly reversed CSS-induced splenic immunosuppression but adversely affected survival in CSS-exposed mice. Additionally, denervation or OTR antagonism reduced the mice's response to social defeat, as shown by decreased social avoidance behavior. These findings suggest that OT-mediated immunosuppression likely represents a compensatory mechanism in response to chronic social stress. Targeting the OT-immune axis could offer innovative therapeutic approaches for stress-associated disorders by restoring immune homeostasis while maintaining behavioral integrity.

Vps34-orchestrated lipid signaling processes regulate the transitional heterogeneity and functional adaptation of effector regulatory T cells

Regulatory T cell (Treg) heterogeneity exists in lymphoid and non-lymphoid tissues, but we have limited understanding of context-dependent functions and spatiotemporal regulators of heterogenous Treg states, especially during perinatal life when immune tolerance is established. Here, we revealed that the class III PI3K Vps34 orchestrates effector Treg (eTreg) transitional heterogeneity during perinatal life. We found that loss of Vps34 reduced terminal eTreg accumulation in lymphoid tissues, associated with decreased Treg generation in non-lymphoid tissues and development of an early-onset autoimmune-like disease. After perinatal life, Vps34-deficient eTreg accumulation was further impaired due to reduced cell survival, highlighting temporal regulation of eTreg heterogeneity and maintenance by Vps34. Accordingly, inhibition of Vps34 in mature Tregs disrupted immune homeostasis but boosted anti-tumor immunity. Mechanistically, multiomics profiling approaches uncovered that Vps34-orchestrated transcriptional and epigenetic remodeling promotes terminal eTreg programming. Further, via genetic deletion of the Vps34-interacting proteins Atg14 or Uvrag in Tregs, we established that Atg14 but not Uvrag was required for the overall survival, but not terminal differentiation, of eTregs, suggesting that autophagy but not endocytosis partly contributed to Vps34-dependent effects. Accordingly, mice with Treg-specific loss of Atg14, but not Uvrag, had moderately disrupted immune homeostasis and reduced tumor growth, with Vps34- or Atg14-dependent gene signatures also being elevated in intratumoral Tregs from human cancer patients. Collectively, our study reveals distinct Vps34-orchestrated signaling events that regulate eTreg heterogeneity and functional adaptation and the pathophysiological consequences on autoimmunity versus anti-tumor immunity.

Foxp3+CD8+ regulatory T cells: bona fide Tregs with cytotoxic function

Various mammalian CD8+ T cell subsets with regulatory properties are either formed through a thymus-dependent mechanism or induced under various experimental protocols and referred to as CD8+ regulatory T cells (Tregs). CD8+ Tregs maintain distinct functions in the presence of CD4+ Tregs. This review focuses on the Foxp3+CD8+ Treg subset, which is typically extremely rare in unmanipulated mice and healthy humans under steady-state conditions. However, they can be induced and expanded for transplantation, autoimmune diseases, cancer, viral infections, and T cell receptor transgenic adoptive cell transfer models. Here, we summarize recent research progress related to this population, including the identification of phenotypic markers, induction determinants, and functional activities. Additionally, we discuss advances in manipulating Foxp3+CD8+ Tregs in autoimmunity and transplantation.

CAR T-cell therapy in autoimmune diseases: where are we and where are we going?

Chimeric antigen receptor (CAR)-based therapies developed for the treatment of haematological malignancies have recently been repurposed to treat refractory systemic autoimmune diseases. In this Review we critically discuss the current data available on the use of CAR-based therapy in systemic autoimmune diseases, the current challenges, and the potential next steps toward their implementation into clinical practice. Beyond the targeting of B cells via CD19, we discuss the advantages and potential pitfalls of targeting plasma cells (B-cell Maturation Antigen or CD138) and other non-immune targets, such as fibroblast activated protein, and of aiming to restore immune homeostasis using CAR T regulatory cells. Crucial points need to be addressed for CAR-based therapy to become a viable treatment option for patients with systemic autoimmune diseases.

The "brain-gut" mechanism of postherpetic neuralgia: a mini-review

Postherpetic neuralgia (PHN), a representative type of neuropathic pain, has attracted much research on its diagnosis and therapy at the molecular level. Interestingly, this study based on the brain-gut axis provided a novel point of view to interpret the mechanism of PHN. Past neuroanatomical and neuroimaging studies of pain suggest that the prefrontal cortex, anterior cingulate cortex, amygdala, and other regions of the brain may play crucial roles in the descending inhibition of PHN. Dominant bacterial species in patients with PHN, such as Lactobacillus, generate short-chain fatty acids, including butyrate. Evidence indicates that disturbance of some metabolites (such as butyrate) is closely related to the development of hyperalgesia. In addition, tryptophan and 5-HT in the intestinal tract act as neurotransmitters that regulate the descending transmission of neuropathic pain signals. Concurrently, the enteric nervous system establishes close connections with the central nervous system through the vagus nerve and other pathways. This review aims to investigate and elucidate the molecular mechanisms associated with PHN, focusing on the interplay among PHN, the gut microbiota, and relevant metabolites while scrutinizing its pathogenesis.

Plasma Exosomes Derived from Patients with Primary Immune Thrombocytopenia Attenuate TBX21+ Regulatory T Cell-Mediated Immune Suppression via MiR-363-3p

Primary Immune Thrombocytopenia (ITP) is characterized by reduced immunosuppressive function of regulatory T cells (Tregs), contributing to immune imbalance and decreased platelet counts. However, the mechanisms behind this reduced efficacy of Tregs remain unclear. Our study used a variety of methods, including Treg function assays, cytokine analysis, and single-cell sequencing, to explore these mechanisms. We found that exosomes from ITP patients inhibited TBX21 expression in Tregs, and impaired their ability to suppress Th1 cells. At the single-cell level, Tregs with high TBX21 expression were identified, and the activity of the TBX21 regulon was found to be enhanced in early-stage Treg subpopulations. We also discovered that ARID3A interacted with SPI1 and TBX21 gene regions, indicating a regulatory relationship between ARID3A, SPI1, and TBX21. Additionally, exosomes in ITP patients' plasma contained elevated levels of miR-363-3p, which negatively correlated with platelet count. These exosomes transferred miR-363-3p to Tregs, downregulating ARID3A, SPI1, and TBX21 expression, thereby weakening Tregs' ability to suppress conventional CD4 + T cells. In conclusion, exosomes from ITP patients reduced Treg function through the ARID3A/SPI1/TBX21 axis by miR-363-3p, diminishing their ability to regulate Th1 cells and contributing to the immune dysfunction observed in ITP.

Integrated metabolomics and mass spectrometry imaging analysis reveal the efficacy and mechanism of Huangkui capsule on type 2 diabetic nephropathy

BACKGROUND

Huangkui capsule (HKC), a Chinese patent medicine, is clinically used for treating diabetic nephropathy. However, the core disease-specific biomarkers and targets of type 2 diabetic nephropathy (T2DN) and the therapeutic mechanism of HKC are not fully elucidated.

PURPOSE

This study aimed to investigate the therapeutic effects and underlying molecular mechanisms of HKC for T2DN.

STUDY DESIGN

The db/db mouse model was used to evaluate the efficacy of HKC for T2DN, and the core pathways regulated by HKC were studied to determine its kidney protective mechanism.

METHODS

High-throughput UPLC-MS/MS and multivariate analysis were employed to analyze the serum and kidney metabolic profiles of db/db mice, identifying potential core biomarkers of T2DN. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry imaging was used to locate in situ spatial distribution of core biomarkers and drug active ingredients in kidney tissues. Biochemical indicators, histopathology, immunohistochemistry, immunofluorescence, molecular docking, and western blotting were combined to reveal therapeutic effects, pathways, and targets of HKC.

RESULTS

HKC substantially improved pathological characteristics, kidney function, oxidative stress, inflammation, and lipid metabolism indicators of T2DN. Twelve core disease-specific biomarker that significantly influenced clustering were identified and its unique spatial distribution information in the kidneys was revealed. 3-dehydrosphinganine, retinyl ester, and 9-cis-retinoic acid (9cRA) could serve as novel disease-specific biomarkers for T2DN. Based on newly discovered biomarkers, quercetin, myricetin, and isorhamnetin were found to act on key enzymes SPT, ALDH1A1, AOX, LRAT, and DGAT1 in retinol and sphingolipid metabolism pathways. Western blotting showed that HKC ameliorated T2DN by targeting these enzymes, upregulating 9cRA and retinyl ester, downregulating 3-dehydrosphinganine, increasing TGF-β signal transduction, inhibiting the expression of the immune fibrosis proteins OX-8, Col-I and α-SMA, inhibiting Th17 cell development and ceramide synthesis, reducing IL-1β, TNF-α, MDA, TC, LDL-C, and TG levels, and increaseing SOD activity.

CONCLUSIONS

HKC exerts significant therapeutic effects on T2DN. HKC corrects the metabolic disorder of sphingolipids and retinol, and improves T2DN by regulating the activities of SPT, ALDH1A1, AOX, LRAT, and DGAT1. This study provides valuable ideas and new mechanistic insights for the treatment of T2DN with HKC.

Cancer stem cells and niches: challenges in immunotherapy resistance

Cancer stem cells (CSCs) are central to tumor progression, metastasis, immune evasion, and therapeutic resistance. Characterized by remarkable self-renewal and adaptability, CSCs can transition dynamically between stem-like and differentiated states in response to external stimuli, a process termed "CSC plasticity." This adaptability underpins their resilience to therapies, including immune checkpoint inhibitors and adoptive cell therapies (ACT). Beyond intrinsic properties, CSCs reside in a specialized microenvironment-the CSC niche-which provides immune-privileged protection, sustains their stemness, and fosters immune suppression. This review highlights the critical role of CSCs and their niche in driving immunotherapy resistance, emphasizing the need for integrative approaches to overcome these challenges.

Synthetic receptor-based cell therapies for autoimmune diseases: an update

Increasing frequency of autoimmune diseases is one of the major problems in modern societies. Despite the introduction of new therapeutic agents for autoimmunity over the past several decades, more progress is needed. Synthetic receptor-based cell therapies are being adopted as an option for treating autoimmune diseases from the field of oncology. Currently evaluated strategies can be summarized into two approaches. The first one is the elimination of autoreactive cells by targeting them, for example, with CAR-T or CAAR-T cells. The second is based on rebalancing the proinflammatory milieu with engineered immunosuppressive cells, for example, CAR-Treg. Both approaches can be supplemented with the use of synthetic systems such as Split-CAR, SynNotch, MESA, GEMS, and SNIPR, or prospective off-the-shelf approaches, for example, in situ use of the in vitro transcribed mRNA, ultimately allowing for enhanced efficacy and safety. The primary goal of our review is to provide some perspective on both strategies in basic, translational, and clinical studies with all their advantages and disadvantages to allow for informed future design of adoptive cell therapies for autoimmune diseases.

How to focus on autoantigen-specific lymphocytes: a review on diagnosis and treatment of Sjogren's syndrome

Sjogren's syndrome (SS) is an autoimmune epithelitis characterized by focal lymphocytic infiltration against self-antigens leading to progressive glandular dysfunction, which can develop to multisystem manifestation. The classification criteria for SS emphasizes glandular lymphocyte infiltrates and anti-SSA/SSB seropositivity, which is usually manifested in advanced patients. Therapeutically, apart from symptomatic treatment, treatment of SS is based on glucocorticoids and conventional synthetic disease-modifying antirheumatic drugs with global immunosuppression, but the efficacy of biologic or targeted synthetic therapies is still sparse. Currently, emerging studies focus on autoantigen-specific immunotherapies to treat autoimmune disorders by directly eliminating autoreactive cell subsets and inducing tolerance by increasing the autoreactive regulatory lymphocytes. Herein, we summarize the current state of research on the autoantigen-specific approaches for detecting autoreactive lymphocytes and outline the current autoantigen-specific immunotherapies in other autoimmune disorders and their attempts in treatment of SS. Last, we discuss the potential value of focusing on autoantigen-specific lymphocytes in the early diagnosis, monitoring, and targeted treatment of SS. Potential strategies for targeting autoreactive lymphocytes need to be confirmed in SS.

T-regulatory cells for the treatment of autoimmune diseases

Autoimmune diseases result from imbalances in the immune system and disturbances in the mechanisms of immune tolerance. T-regulatory cells (Treg) are key factors in the formation of immune tolerance. Tregs modulate immune responses and repair processes, controlling the innate and adaptive immune system. The use of Tregs in the treatment of autoimmune diseases began with the manipulation of endogenous Tregs using immunomodulatory drugs. Then, a method of adoptive transfer of Tregs grown in vitro was developed. Adoptive transfer of Tregs includes polyclonal Tregs with non-specific effects and antigen-specific Tregs in the form of CAR-Treg and TCR-Treg. This review discusses non-specific and antigen-specific approaches to the use of Tregs, their advantages, disadvantages, gaps in development, and future prospects.

Single cell suppression profiling of human regulatory T cells

Regulatory T cells (Treg) play an important role in regulating immune homeostasis in health and disease. Traditionally their suppressive function has been assayed by mixing purified cell populations, which does not provide an accurate picture of a physiologically relevant response. To overcome this limitation, we here develop 'single cell suppression profiling of human Tregs' (scSPOT). scSPOT uses a 52-marker CyTOF panel, a cell division detection algorithm, and a whole PBMC system to assess the effect of Tregs on all other cell types simultaneously. In this head-to-head comparison, we find Tregs having the clearest suppressive effects on effector memory CD8 T cells through partial division arrest, cell cycle inhibition, and effector molecule downregulation. Additionally, scSPOT identifies a Treg phenotypic split previously observed in viral infection and propose modes of action by the FDA-approved drugs Ipilimumab and Tazemetostat. scSPOT is thus scalable, robust, widely applicable, and may be used to better understand Treg immunobiology and screen for therapeutic compounds.

Improving regulatory T cell-based therapy: insights into post-translational modification regulation

Regulatory T (Treg) cells are pivotal for maintaining immune homeostasis and play essential roles in various diseases, such as autoimmune diseases, graft-versus-host disease (GVHD), tumors, and infectious diseases. Treg cells exert suppressive function via distinct mechanisms, including inhibitory cytokines, granzyme or perforin-mediated cytolysis, metabolic disruption, and suppression of dendritic cells. Forkhead Box P3 (FOXP3), the characteristic transcription factor, is essential for Treg cell function and plasticity. Cumulative evidence has demonstrated that FOXP3 activity and Treg cell function are modulated by a variety of post-translational modifications (PTMs), including ubiquitination, acetylation, phosphorylation, methylation, glycosylation, poly(ADP-ribosyl)ation, and uncharacterized modifications. This review describes Treg cell suppressive mechanisms and summarizes the current evidence on PTM regulation of FOXP3 and Treg cell function. Understanding the regulatory role of PTMs in Treg cell plasticity and function will be helpful in designing therapeutic strategies for autoimmune diseases, GVHD, tumors, and infectious diseases.

CXCR5-targeted chimeric antigen receptor T regulatory cells for the selective inhibition of follicular helper T cell and B cell interaction

BACKGROUND

The dysregulation of follicular helper T (Tfh) cell function, followed by the proliferation of self-reactive B cells, can lead to the development of autoimmune diseases. Recently, adaptive T regulatory cell (Treg) transfer therapy has attracted considerable attention for inducing effective immune tolerance owing to Tregs' diverse immune-inhibitory activities. However, preclinical studies and recent clinical trials of polyclonal Treg therapy have suggested further improving the efficacy of Treg therapy through targeted tissue specificity and local persistence by gene engineering. In this study, we reported a novel approach to specifically inhibit Tfh cells by CXC motif chemokine receptor 5-targeted chimeric antigen receptor (CXCR5-CAR) Tregs.

METHODS

Tregs expressing CAR against CXCR5 were generated from human peripheral blood mononuclear cells-derived Tregs. The phenotype and suppressive capacity of the engineered Tregs were evaluated using coculture assays with naïve T cells, circulating Tfh (cTfh) cells, or a combination of cTfh cells and naïve B cells through flow cytometry analysis.

RESULT

CXCR5-CAR Tregs induced more potent inhibition of circulating cTfh cell proliferation while maintaining similar suppressive properties on CXCR5-negative responder cells compared with non-selective polyclonal Tregs. The antigen-dependent activation of CXCR5-CAR Tregs was confirmed by latency-associated peptide (LAP) expression in the coculture with cTfh cells. In the coculture condition with both cTfh and naïve B cells, the activation of naïve B cells induced by cTfh cells was more effectively inhibited by CXCR5-CAR Tregs than by polyclonal Tregs.

CONCLUSION

The results demonstrate the potential of CXCR5-CAR Tregs to effectively inhibit the Tfh-B cell response in autoimmune diseases, paving the way for further research to confirm their functional superiority in vivo. This novel approach offers promise for achieving local, long-term immune tolerance compared with existing approaches such as nonspecific immunosuppression and polyclonal Treg therapy.

Engineering synthetic suppressor T cells that execute locally targeted immunoprotective programs

Immune homeostasis requires a balance of inflammatory and suppressive activities. To design cells potentially useful for local immune suppression, we engineered conventional CD4+ T cells with synthetic Notch (synNotch) receptors driving antigen-triggered production of anti-inflammatory payloads. Screening a diverse library of suppression programs, we observed the strongest suppression of cytotoxic T cell attack by the production of both anti-inflammatory factors (interleukin-10, transforming growth factor-β1, programmed death ligand 1) and sinks for proinflammatory cytokines (interleukin-2 receptor subunit CD25). Engineered cells with bespoke regulatory programs protected tissues from immune attack without systemic suppression. Synthetic suppressor T cells protected transplanted beta cell organoids from cytotoxic T cells. They also protected specific tissues from unwanted chimeric antigen receptor (CAR) T cell cross-reaction. Synthetic suppressor T cells are a customizable platform to potentially treat autoimmune diseases, organ rejection, and CAR T cell toxicities with spatial precision.

Granzyme B May Act as an Effector Molecule to Control the Inflammatory Process in COPD

Chronic obstructive pulmonary disease (COPD) is caused by smoking, but only a small proportion of smokers have disease severe enough to develop COPD. COPD is not always progressive. The question then arises as to what explains the different trajectories of COPD. The role of autoimmunity and regulatory T (Treg) cells in the pathogenesis of COPD is increasingly being recognized. Nine published studies on Treg cells in the lung tissue or bronchoalveolar lavage fluid have shown that smokers with COPD have fewer Treg cells than smokers without COPD or nonsmokers. Three studies showed a positive correlation between Treg cell count and FEV1%, suggesting an important role for Treg cells in COPD progression. Treg cells can regulate immunological responses via the granzyme B (GzmB) pathway. Immunohistochemical staining for GzmB in surgically resected lungs with centrilobular emphysema showed that the relationship between the amount of GzmB+ cells and FEV1% was comparable to that between Treg cell count and FEV1% in the COPD lung, suggesting that GzmB could be a functional marker for Treg cells. The volume fraction of GzmB+  cells in the small airways, the number of alveolar GzmB+ cells, and GzmB expression measured by enzyme-linked immunosorbent assay in the lung tissue of smokers were significantly correlated with FEV1%. These results suggest that the GzmB content in lung tissue may determine the progression of COPD by acting as an effector molecule to control inflammatory process. Interventions to augment GzmB-producing immunosuppressive cells in the early stages of COPD could help prevent or delay COPD progression.

Chimeric antigen receptor T-cell therapy in autoimmune diseases

The administration of T cells that have been modified to carry chimeric antigen receptors (CARs) aimed at B cells has been an effective strategy in treating B cell malignancies. This breakthrough has spurred the creation of CAR T cells intended to specifically reduce or alter the faulty immune responses associated with autoimmune disorders. Early positive outcomes from clinical trials involving CAR T cells that target the B cell protein CD19 in patients suffering from autoimmune diseases driven by B cells have been reported. Additional strategies are being developed to broaden the use of CAR T cell therapy and enhance its safety in autoimmune conditions. These include employing chimeric autoantireceptors (CAAR) to specifically eliminate B cells that are reactive to autoantigens, and using regulatory T cells (Tregs) engineered to carry antigen-specific CARs for precise immune modulation. This discussion emphasizes key factors such as choosing the right target cell groups, designing CAR constructs, defining tolerable side effects, and achieving a lasting immune modification, all of which are critical for safely integrating CAR T cell therapy in treating autoimmune diseases.

The immune landscape in apical periodontitis: From mechanism to therapy

Apical periodontitis (AP) is featured by a persistent inflammatory response and alveolar bone resorption initiated by microorganisms, posing risks to both dental and systemic health. Nonsurgical endodontic treatment is the recommended treatment plan for AP with a high success rate, but in some cases, periapical lesions may persist despite standard endodontic treatment. Better comprehension of the AP inflammatory microenvironment can help develop adjunct therapies to improve the outcome of endodontic treatment. This review presents an overview of the immune landscape in AP, elucidating how microbial invasion triggers host immune activation and shapes the inflammatory microenvironment, ultimately impacting bone homeostasis. The destructive effect of excessive immune activation on periapical tissues is emphasized. This review aimed to systematically discuss the immunological basis of AP, the inflammatory bone resorption and the immune cell network in AP, thereby providing insights into potential immunotherapeutic strategies such as targeted therapy, antioxidant therapy, adoptive cell therapy and cytokine therapy to mitigate AP-associated tissue destruction.

Subcutaneously transplanted xenogeneic protein recruits treg cells and M2 macrophages to induce browning of inguinal white adipose tissue

OBJECTIVE

To study whether subcutaneously embedding xenogeneic protein threads or synthetic polymer absorbable threads can improve obesity phenotypes and metabolic conditions, and to further explore its underlying mechanism.

METHODS

Thirty-six 8-week-old ob/ob mice were randomly allocated to three groups, respectively, receiving catgut embedding, PGA thread embedding or sham treatment bilaterally to the groin. Individual parameters including weight, food intake, and core temperature are recorded and metabolism assessment, energy expenditure analysis, and PET/CT scanning are also performed at fixed timepoints. After surgical incision, the inguinal white adipose tissue was histologically examined and its expression profile was tested and compared among groups 4 weeks and 12 weeks after operation.

RESULTS

Catgut embedding reduced weight gain and improved metabolic status in ob/ob mice. Browning of bilateral inguinal WAT (white adipose tissue) was induced after catgut embedding, with massive infiltration of Treg cells and M2 macrophages in the tissue slices of fat pads. IL-10 and TGF-β released by Treg cells targeted macrophages and the induced M2 macrophages increased the expression of thermogenic and anti-inflammatory genes in fat. The secretion of catecholamines by polarized M2 macrophages led to the activation of β3-AR-related pathways in adipocytes and the browning of adipose tissue.

CONCLUSIONS

Abdominal subcutaneous catgut embedding has the potential to combat obesity through the induction of WAT browning mediated by infiltrated Treg cells and macrophages.

Metabolite, immunocyte phenotype, and lymphoma: a Mendelian randomization study

Background

Recent studies have confirmed that metabolites and immunocyte phenotype may be associated with the risk of lymphoma. However, the bidirectional causality between metabolites, immunocyte phenotype, disease risk, and whether immunity is an intermediate mediator between metabolism and lymphoma causality is still unclear.

Objective

To elucidate the causal relationship between metabolites, immune cell phenotypes, and lymphomas, we used two-sample Mendelian randomization (MR) and two-step MR analysis.

Methods

Applying large-scale genome-wide association studies (GWAS) pooled data, we selected 1400 metabolites and 731 immunocyte phenotypes with eight lymphoma subtypes for two-sample bi-directional MR analysis. In addition, we used two-step MR to quantify the proportion of metabolite effects on lymphomas mediated by immunocyte phenotype.

Results

This study yielded a bidirectional causal relationship between 17 metabolites and lymphoma and a bidirectional causal relationship between 12 immunocyte phenotypes and lymphoma. In addition, we found causal associations between metabolites and lymphomas, three groups of which were mediated by immunocyte phenotypes. Among them, CD27 on plasmablast/plasma cell (PB/PC) was a mediator of the positive association of arginine to glutamate ratio with chronic lymphocytic leukemia, with a mediator ratio of 14.60% (95% CI=1.29-28.00%, P=3.17 × 10-2). Natural killer (NK) cells as a percentage of all lymphocytes(NK %lymphocyte) was a mediator of the negative association of X-18922(unknown metabolite) levels with diffuse large B-cell lymphoma, with a mediation proportion of -8.940% (95% CI=-0.063-(-17.800) %, P=4.84 × 10-2). CD25 on IgD- CD24- B cell was the mediator of the positive association between X-24531(unknown metabolite) levels and diffuse large B-cell lymphoma, with a mediation proportion of 13.200% (95% CI=-0.156-26.200%, P=4.73 × 10-2).

Conclusion

In the present study, we identified a causal relationship between metabolites and lymphoma, in which immunocyte phenotypes as mediators are involved in only a minor part. The mediators by which most metabolites affect the risk of lymphoma development remain unclear and require further exploration in the future.

Histone deacetylases facilitate Th17-cell differentiation and pathogenicity in autoimmune uveitis via CDK6/ID2 axis

INTRODUCTION

Autoimmune uveitis (AU) is a prevalent ocular autoimmune disease leading to significant visual impairment. However, underlying pathogenesis of AU required to develop more efficient therapy remain unclear.

METHODS

We isolated peripheral blood mononuclear cells (PBMCs) from AU patients and performed single-cell RNA sequencing (scRNA-seq). Besides, experimental autoimmune uveitis (EAU) model was established and treated with histone deacetylase inhibitor (HDACi) Belinostat or vehicle. We extracted immune cells from Blank, EAU, and HDACi-treated EAU mice and used scRNA-seq, flow cytometry, siRNA, specific inhibitors, and adoptive transfer experiments to explore the role of HDACs and its downstream potential molecular mechanisms in the immune response of EAU and AU.

RESULTS

We found highly expressed histone deacetylases (HDACs) family in AU patients and identified it as a key factor related to CD4+ effector T cell differentiation in the pathogenesis of AU. Our further studies showed that targeted inhibition of HDACs effectively alleviated EAU, restored its Th17/Treg balance, and reduced inflammatory gene expression, especially in CD4+ T cells. Post-HDACs inhibition, Treg proportions increased with enhanced immunomodulatory effects. Importantly, HDACs exhibited a positive promoting role on Th17 cells. Based on scRNA-seq screening and application of knock-down siRNAs and specific inhibitors in vitro and vivo, we identified CDK6 as a key downstream molecule regulated by HDAC1/3/6 through acetyl-histone H3/p53/p21 axis, which is involved in Th17 pathogenicity and EAU development. Additionally, HDACs-regulated CDK6 formed a positive loop with ID2, inducing PIM1 upregulation, promoting Th17 cell differentiation and pathogenicity, and correlates with AU progression.

CONCLUSION

Based on the screening of clinical samples and downstream molecular functional validation experiments, we revealed a driving role for HDACs and the HDACs-regulated CDK6/ID2 axis in Th17 cell differentiation and pathogenicity in AU, proposing a promising therapeutic strategy.

Engineered immune cells as therapeutics for autoimmune diseases

Current treatment options for autoimmune disease (AID) are essentially immunosuppressive, inhibiting the inflammatory cascade, without curing the disease. Therapeutic monoclonal antibodies (mAbs) that target B cells showed efficacy, emphasizing the importance of B lymphocytes in autoimmune pathogenesis. Treatments that eliminate more potently B cells would open a new therapeutic era for AID. Immune cells can now be bioengineered to express constructs that enable them to specifically eradicate pathogenic B lymphocytes. Engineered immune cells (EICs) have shown therapeutic promise in both experimental models and in clinical trials in AID. Next-generation platforms are under development to optimize their specificity and improve safety. The profound and durable B cell depletion achieved reinforces the view that this biotherapeutic option holds promise for treating AID.

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

Regulatory T Cell Dysfunction in Autoimmune Diseases

Regulatory T cells (Tregs), a suppressive subpopulation of T cells, are potent mediators of peripheral tolerance, responsible for immune homeostasis. Many autoimmune diseases exhibit disruptions in Treg function or quantity, resulting in an imbalance between protective and pathogenic immune cells. Selective expansion or manipulation of Tregs is a promising therapeutic approach for autoimmune diseases. However, the extensive diversity of Treg subpopulations and the multiple approaches used for Treg identification leads to high complexity, making it difficult to develop a successful treatment capable of modulating Tregs. In this review, we describe the suppressive mechanisms, subpopulations, classification, and identification methodology for Tregs, and their role in the pathogenesis of autoimmune diseases.

Combining Treg Therapy With Donor Bone Marrow Transplantation: Experimental Progress and Clinical Perspective

Donor-specific tolerance remains a goal in transplantation because it could improve graft survival and reduce morbidity. Cotransplantation of donor hematopoietic cells to achieve chimerism is a promising approach for tolerance induction, which was successfully tested in clinical trials. However, current protocols are associated with side effects related to the myelosuppressive recipient conditioning, which makes it difficult to introduce them as standard therapy. More recently, adoptive cell therapy with polyclonal or donor-specific regulatory T cells (Treg) proved safe and feasible in several transplant trials, but it is unclear whether it can induce tolerance on its own. The combination of both approaches-Treg therapy and hematopoietic cell transplantation-leads to chimerism and tolerance without myelosuppressive treatment in murine models. Treg therapy promotes engraftment of allogeneic hematopoietic cells, reducing conditioning requirements and enhancing regulatory mechanisms maintaining tolerance. This review discusses possible modes of action of transferred Treg in experimental chimerism models and describes translational efforts investigating the potent synergy of Treg and chimerism.

Brain regulatory T cells

The brain, long thought to be isolated from the peripheral immune system, is increasingly recognized to be integrated into a systemic immunological network. These conduits of immune-brain interaction and immunosurveillance processes necessitate the presence of complementary immunoregulatory mechanisms, of which brain regulatory T cells (Treg cells) are likely a key facet. Treg cells represent a dynamic population in the brain, with continual influx, specialization to a brain-residency phenotype and relatively rapid displacement by newly incoming cells. In addition to their functions in suppressing adaptive immunity, an emerging view is that Treg cells in the brain dampen down glial reactivity in response to a range of neurological insults, and directly assist in multiple regenerative and reparative processes during tissue pathology. The utility and malleability of the brain Treg cell population make it an attractive therapeutic target across the full spectrum of neurological conditions, ranging from neuroinflammatory to neurodegenerative and even psychiatric diseases. Therapeutic modalities currently under intense development include Treg cell therapy, IL-2 therapy to boost Treg cell numbers and multiple innovative approaches to couple these therapeutics to brain delivery mechanisms for enhanced potency. Here we review the state of the art of brain Treg cell knowledge together with the potential avenues for future integration into medical practice.

Developing CAR-immune cell therapy against SARS-CoV-2: Current status, challenges and prospects

Chimeric antigen receptor (CAR)-immune cell therapy has revolutionized the anti-tumor field, achieving efficient and precise tumor clearance by directly guiding immune cell activity to target tumors. In addition, the use of CAR-immune cells to influence the composition and function of the immune system and ultimately achieve virus clearance and immune system homeostasis has attracted the interest of researchers. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) triggered a global pandemic of coronavirus disease 2019 (COVID-19). To date, the rapidly mutating SARS-CoV-2 continues to challenge existing therapies and has raised public concerns regarding reinfection. In patients with COVID-19, the interaction of SARS-CoV-2 with the immune system influences the course of the disease, and the coexistence of over-activated immune system components, such as macrophages, and severely compromised immune system components, such as natural killer cells, reveals a dysregulated immune system. Dysregulated immune-induced inflammation may impair viral clearance and T-cell responses, causing cytokine storms and ultimately leading to patient death. Here, we summarize the research progress on the use of CAR-immune cells against SARS-CoV-2 infection. Furthermore, we discuss the feasibility, challenges and prospect of CAR-immune cells as a new immune candidate therapy against SARS-CoV-2.

The New Frontiers of Gene Therapy and Gene Editing in Inflammatory Diseases

Inflammatory diseases are conditions characterized by abnormal and often excessive immune responses, leading to tissue and organ inflammation. The complexity of these disorders arises from the intricate interplay of genetic factors and immune responses, which challenges conventional therapeutic approaches. However, the field of genetic manipulation has sparked unprecedented optimism in addressing these complex disorders. This review aims to comprehensively explore the application of gene therapy and gene editing in the context of inflammatory diseases, offering solutions that range from correcting genetic defects to precise immune modulation. These therapies have exhibited remarkable potential in ameliorating symptoms, improving quality of life, and even achieving disease remission. As we delve into recent breakthroughs and therapeutic applications, we illustrate how these advancements offer novel and transformative solutions for conditions that have traditionally eluded conventional treatments. By examining successful case studies and preclinical research, we emphasize the favorable results and substantial transformative impacts that gene-based interventions have demonstrated in patients and animal models of inflammatory diseases such as chronic granulomatous disease, cryopyrin-associated syndromes, and adenosine deaminase 2 deficiency, as well as those of multifactorial origins such as arthropathies (osteoarthritis, rheumatoid arthritis) and inflammatory bowel disease. In conclusion, gene therapy and gene editing offer transformative opportunities to address the underlying causes of inflammatory diseases, ushering in a new era of precision medicine and providing hope for personalized, targeted treatments.

Engineering transcriptional regulation for cell-based therapies

A major aim in the field of synthetic biology is developing tools capable of responding to user-defined inputs by activating therapeutically relevant cellular functions. Gene transcription and regulation in response to external stimuli are some of the most powerful and versatile of these cellular functions being explored. Motivated by the success of chimeric antigen receptor (CAR) T-cell therapies, transmembrane receptor-based platforms have been embraced for their ability to sense extracellular ligands and to subsequently activate intracellular signal transduction. The integration of transmembrane receptors with transcriptional activation platforms has not yet achieved its full potential. Transient expression of plasmid DNA is often used to explore gene regulation platforms in vitro. However, applications capable of targeting therapeutically relevant endogenous or stably integrated genes are more clinically relevant. Gene regulation may allow for engineered cells to traffic into tissues of interest and secrete functional proteins into the extracellular space or to differentiate into functional cells. Transmembrane receptors that regulate transcription have the potential to revolutionize cell therapies in a myriad of applications, including cancer treatment and regenerative medicine. In this review, we will examine current engineering approaches to control transcription in mammalian cells with an emphasis on systems that can be selectively activated in response to extracellular signals. We will also speculate on the potential therapeutic applications of these technologies and examine promising approaches to expand their capabilities and tighten the control of gene regulation in cellular therapies.

Promises and Pitfalls of Next-Generation Treg Adoptive Immunotherapy

Regulatory T cells (Tregs) are fundamental to maintaining immune homeostasis by inhibiting immune responses to self-antigens and preventing the excessive activation of the immune system. Their functions extend beyond immune surveillance and subpopulations of tissue-resident Treg cells can also facilitate tissue repair and homeostasis. The unique ability to regulate aberrant immune responses has generated the concept of harnessing Tregs as a new cellular immunotherapy approach for reshaping undesired immune reactions in autoimmune diseases and allo-responses in transplantation to ultimately re-establish tolerance. However, a number of issues limit the broad clinical applicability of Treg adoptive immunotherapy, including the lack of antigen specificity, heterogeneity within the Treg population, poor persistence, functional Treg impairment in disease states, and in vivo plasticity that results in the loss of suppressive function. Although the early-phase clinical trials of Treg cell therapy have shown the feasibility and tolerability of the approach in several conditions, its efficacy has remained questionable. Leveraging the smart tools and platforms that have been successfully developed for primary T cell engineering in cancer, the field has now shifted towards "next-generation" adoptive Treg immunotherapy, where genetically modified Treg products with improved characteristics are being generated, as regards antigen specificity, function, persistence, and immunogenicity. Here, we review the state of the art on Treg adoptive immunotherapy and progress beyond it, while critically evaluating the hurdles and opportunities towards the materialization of Tregs as a living drug therapy for various inflammation states and the broad clinical translation of Treg therapeutics.

A novel FOXP3 knockout-humanized mouse model for pre-clinical safety and efficacy evaluation of Treg-like cell products

Forkhead box P3 (FOXP3) is an essential transcription factor for regulatory T cell (Treg) function. Defects in Tregs mediate many immune diseases including the monogenic autoimmune disease immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX), which is caused by FOXP3 mutations. Treg cell products are a promising modality to induce allograft tolerance or reduce the use of immunosuppressive drugs to prevent rejection, as well as in the treatment of acquired autoimmune diseases. We have recently opened a phase I clinical trial for IPEX patients using autologous engineered Treg-like cells, CD4LVFOXP3. To facilitate the pre-clinical studies, a novel humanized-mouse (hu-mouse) model was developed whereby immune-deficient mice were transplanted with human hematopoietic stem progenitor cells (HSPCs) in which the FOXP3 gene was knocked out (FOXP3KO) using CRISPR-Cas9. Mice transplanted with FOXP3KO HSPCs had impaired survival, developed lymphoproliferation 10-12 weeks post-transplant and T cell infiltration of the gut, resembling human IPEX. Strikingly, injection of CD4LVFOXP3 into the FOXP3KO hu-mice restored in vivo regulatory functions, including control of lymphoproliferation and inhibition of T cell infiltration in the colon. This hu-mouse disease model can be reproducibly established and constitutes an ideal model to assess pre-clinical efficacy of human Treg cell investigational products.