Regulatory T cell memory

Subpopulations of regulatory T cells are associated with subclinical atherosclerotic plaques, levels of LDL, and cardiorespiratory fitness in the elderly

BACKGROUND

Atherosclerosis forms the pathological basis for the development of cardiovascular disease. Since pathological processes initially develop without clinically relevant symptoms, the identification of early markers in the subclinical stage plays an important role for initiating early interventions. There is evidence that regulatory T cells (Tregs) are involved in the development of atherosclerosis. Therefore, the present study aimed to identify and investigate associations with Tregs and their subsets in a cohort of healthy elderly individuals with and without subclinical atherosclerotic plaques (SAP). In addition, various lifestyle and risk factors, such as cardiorespiratory fitness, were investigated as associated signatures.

METHODS

A cross-sectional study was performed in 79 participants (male: n = 50; age = 63.6 ± 3.7 years; body mass index = 24.9 ± 3.1 kg/m²; mean ± SD) who had no previous diagnosis of chronic disease and were not taking medication. Ultrasound of the carotids to identify SAP, cardiovascular function measurement for vascular assessment and a cardiorespiratory fitness test to determine peak oxygen uptake were performed. Additionally, tests were conducted to assess blood lipids and determine glucose levels. Immunophenotyping of Tregs and their subtypes (resting (rTregs) and effector/memory (mTregs)) was performed by 8-chanel flow cytometry. Participants were categorized according to atherosclerotic plaque status. Linear and logistic regression models were used to analyze associations between parameters.

RESULTS

SAP was detected in a total of 29 participants. The participants with plaque were older (64.8 ± 3.6 years vs. 62.9 ± 3.5 years) and had higher peripheral systolic blood pressure (133.8 ± 14.7 mmHg vs. 125.8 ± 10.9 mmHg). The participants with SAP were characterized by a lower percentage of rTregs (28.8% ± 10.7% vs. 34.6% ± 10.7%) and a higher percentage of mTregs (40.3% ± 14.7% vs. 30.0% ± 11.9%). Multiple logistic regression identified age (odds ratio (OR) = 1.20 (95% confidence interval (95%CI): 1.01-1.42)) and mTregs (OR = 1.05 (95%CI: 1.02-1.10)) as independent risk factors for SAP. Stepwise linear regression could reveal an association of peak oxygen uptake (β = 0.441), low-density lipoprotein (LDL) (β = -0.096), and SAP (β = 6.733) with mTregs and LDL (β = 0.104) with rTregs.

CONCLUSION

While at an early stage of SAP, the total proportion of Tregs gives no indication of vascular changes, this is indicated by a shift in the Treg subgroups. Factors such as serum LDL or cardiopulmonary fitness may be associated with this shift and may also be additional diagnostic indicators. This could be used to initiate lifestyle-based preventive measures at an early stage, which may have a protective effect against disease progression.

Carbon quantum dots as immune modulatory therapy in a Sjögren's syndrome mouse model

OBJECTIVES

The objective of the study was to evaluate the therapeutic effects of carbon quantum dots (CQDs) in immunomodulation on non-obese diabetic (NOD) mice, as the model for Sjögren's syndrome (SS).

METHODS

Carbon quantum dots were generated from Setaria viridis via a hydrothermal process. Their toxic effects were tested by cell viability and blood chemistry analysis, meanwhile therapeutic effects were investigated in NOD mice in the aspects of saliva flow, histology, and immune cell distribution.

RESULTS

Carbon quantum dots, with rich surface chemistry and unique optical properties, showed non-cytotoxicity in vitro or no damage in vivo. Intravenously applied CQDs alleviated inflammation in the submandibular glands in NOD mice after 6-week treatments. The inflammatory area index and focus score were significantly decreased in CQD-treated mice. Besides, the levels of anti-SSA and anti-SSB were decreased in the presence of CQDs. The stimulated saliva flow rates and weight of submandibular glands were significantly increased in CQD-treated mice by reducing the apoptosis of cells. The CD3+ and CD4+ T cells distributed around the ducts of submandibular glands were significantly decreased, while the percentage of Foxp3+ cells was higher in CQD-treated mice than that in the control group.

CONCLUSIONS

Our findings suggest that CQDs may ameliorate the dysregulated immune processes in NOD mice.

Differential induction of donor-reactive Foxp3+ regulatory T cell via blockade of CD154 vs CD40

Recently published studies in both murine models and a meta-analysis of non-human primate renal transplant studies showed that anti-CD154 reagents conferred a significant survival advantage over CD40 blockers in both animal models and across multiple organs. Here we sought to compare the induction of donor-reactive forkhead box P3+-induced regulatory T cells (Foxp3+ iTreg) in mice treated with anti-CD154 versus anti-CD40 monoclonal antibodies (mAbs). Results indicated that while treatment with anti-CD154 mAb resulted in a significant increase in the frequency of donor-reactive CD4+ Foxp3+ iTreg following transplantation, treatment with anti-CD40 or Cd40 deficiency failed to recapitulate this result. Because we recently identified CD11b as an alternate receptor for CD154 during alloimmunity, we interrogated the role of CD154:CD11b interactions in the generation of Foxp3+ iTreg and found that blockade of CD11b in Cd40-/- recipients resulted in increased donor-reactive Foxp3+ iTreg as compared with CD40 deficiency alone. Mechanistically, CD154:CD11b inhibition decreased interleukin (IL)-1β from CD11b+ and CD11c+ dendritic cells, and blockade of IL-1β synergized with CD40 deficiency to promote Foxp3+ iTreg induction and prolong allograft survival. Taken together, these data provide a mechanistic basis for the observed inferiority of anti-CD40 blockers as compared with anti-CD154 mAb and illuminate an IL-1β-dependent mechanism by which CD154:CD11b interactions prevent the generation of donor-reactive Foxp3+ iTreg during transplantation.

Characteristics and functions of memory regulatory T cells in normal pregnancy cycle and pregnancy complications

Regulatory T cells (Tregs) are activated and expanded after exposure to fetal-specific (paternal) antigens. A proportion of Tregs differentiate into memory Tregs (mTregs), exhibiting immune memory function and exerting more potent immunosuppression than naive Tregs (nTregs). However, it is unclear how mTregs are regulated during normal and pathological pregnancies (e.g., gestational diabetes mellitus (GDM) and preeclampsia (PE)). In this study, PD-1, HLA-G, and HLA-DR expressions on memory CD4+ T cells, naive CD4+ T cells, Tregs, mTregs, and nTregs in healthy non-pregnant women (n=20), healthy first (n=20), second (n=20), and third-trimester women (n=20), postpartum women (n=20), GDM (n=20), and PE patients (n=20) were analyzed. The proportion of mTregs out of Tregs was increased (P<0.05) in the first trimester compared with that in non-pregnancy and reduced in the second and third trimesters. The proportions of PD-1+ Tregs and mTregs were significantly increased during the first trimester compared to those of non-pregnancy (P<0.01), reached their maximum in the second trimester. Moreover, the proportions of HLA-G+ memory CD4+ T cells, Tregs, and mTregs were increased in the first and second trimesters (P<0.01), reached their maximum in the third trimester. GDM patients were characterized by significantly lower percentages of PD-1+ and HLA-G+ mTregs (P<0.01), while PE patients were characterized by significantly lower percentages of HLA-G+ mTregs (P<0.01), compared with the healthy third-trimester women. In general, as demonstrated by this study, mTregs increase in number and enhance maternal-fetal immunoregulation during pregnancy, and their dysfunction can result in pregnancy complications such as GMD or PE.

IL-23 stabilizes an effector Treg cell program in the tumor microenvironment

Interleukin-23 (IL-23) is a proinflammatory cytokine mainly produced by myeloid cells that promotes tumor growth in various preclinical cancer models and correlates with adverse outcomes. However, as to how IL-23 fuels tumor growth is unclear. Here, we found tumor-associated macrophages to be the main source of IL-23 in mouse and human tumor microenvironments. Among IL-23-sensing cells, we identified a subset of tumor-infiltrating regulatory T (Treg) cells that display a highly suppressive phenotype across mouse and human tumors. The use of three preclinical models of solid cancer in combination with genetic ablation of Il23r in Treg cells revealed that they are responsible for the tumor-promoting effect of IL-23. Mechanistically, we found that IL-23 sensing represents a crucial signal driving the maintenance and stabilization of effector Treg cells involving the transcription factor Foxp3. Our data support that targeting the IL-23/IL-23R axis in cancer may represent a means of eliciting antitumor immunity.

A disrupted FOXP3 transcriptional signature underpins systemic regulatory T cell insufficiency in early pregnancy failure

Regulatory T (Treg) cell defects are implicated in disorders of embryo implantation and placental development, but the origins of Treg cell dysfunction are unknown. Here, we comprehensively analyzed the phenotypes and transcriptional profile of peripheral blood Treg cells in individuals with early pregnancy failure (EPF). Compared to fertile subjects, EPF subjects had 32% fewer total Treg cells and 54% fewer CD45RA+CCR7+ naive Treg cells among CD4+ T cells, an altered Treg cell phenotype with reduced transcription factor FOXP3 and suppressive marker CTLA4 expression, and lower Treg:Th1 and Treg:Th17 ratios. RNA sequencing demonstrated an aberrant gene expression profile, with upregulation of pro-inflammatory genes including CSF2, IL4, IL17A, IL21, and IFNG in EPF Treg cells. In silico analysis revealed 25% of the Treg cell dysregulated genes are targets of FOXP3. We conclude that EPF is associated with systemic Treg cell defects arising due to disrupted FOXP3 transcriptional control and loss of lineage fidelity.

Single-cell transcriptome landscape of circulating CD4+ T cell populations in autoimmune diseases

CD4+ T cells are key mediators of various autoimmune diseases; however, their role in disease progression remains unclear due to cellular heterogeneity. Here, we evaluated CD4+ T cell subpopulations using decomposition-based transcriptome characterization and canonical clustering strategies. This approach identified 12 independent gene programs governing whole CD4+ T cell heterogeneity, which can explain the ambiguity of canonical clustering. In addition, we performed a meta-analysis using public single-cell datasets of over 1.8 million peripheral CD4+ T cells from 953 individuals by projecting cells onto the reference and cataloging cell frequency and qualitative alterations of the populations in 20 diseases. The analyses revealed that the 12 transcriptional programs were useful in characterizing each autoimmune disease and predicting its clinical status. Moreover, genetic variants associated with autoimmune diseases showed disease-specific enrichment within the 12 gene programs. The results collectively provide a landscape of single-cell transcriptomes of CD4+ T cell subpopulations involved in autoimmune disease.

Intragraft memory-like CD127hiCD4+Foxp3+ Tregs maintain transplant tolerance

CD4+Foxp3+ regulatory T cells (Tregs) play an essential role in suppressing transplant rejection, but their role within the graft and heterogeneity in tolerance are poorly understood. Here, we compared phenotypic and transcriptomic characteristics of Treg populations within lymphoid organs and grafts in an islet xenotransplant model of tolerance. We showed Tregs were essential for tolerance induction and maintenance. Tregs demonstrated heterogeneity within the graft and lymphoid organs of tolerant mice. A subpopulation of CD127hi Tregs with memory features were found in lymphoid organs, presented in high proportions within long-surviving islet grafts, and had a transcriptomic and phenotypic profile similar to tissue Tregs. Importantly, these memory-like CD127hi Tregs were better able to prevent rejection by effector T cells, after adoptive transfer into secondary Rag-/- hosts, than naive Tregs or unselected Tregs from tolerant mice. Administration of IL-7 to the CD127hi Treg subset was associated with a strong activation of phosphorylation of STAT5. We proposed that memory-like CD127hi Tregs developed within the draining lymph node and underwent further genetic reprogramming within the graft toward a phenotype that had shared characteristics with other tissue or tumor Tregs. These findings suggested that engineering Tregs with these characteristics either in vivo or for adoptive transfer could enhance transplant tolerance.

Characterization of Immune Cell Populations of Cutaneous Neurofibromas in Neurofibromatosis 1

Cutaneous neurofibromas (cNFs) are characteristic of neurofibromatosis 1 (NF1), yet their immune microenvironment is incompletely known. A total of 61 cNFs from 10 patients with NF1 were immunolabeled for different types of T cells and macrophages, and the cell densities were correlated with clinical characteristics. Eight cNFs and their overlying skin were analyzed for T cell receptor CDR domain sequences, and mass spectrometry of 15 cNFs and the overlying skin was performed to study immune-related processes. Intratumoral T cells were detected in all cNFs. Tumors from individuals younger than the median age of the study participants (33 years), growing tumors, and tumors smaller than the data set median showed increased T cell density. Most samples displayed intratumoral or peritumoral aggregations of CD3-positive cells. T cell receptor sequencing demonstrated that the skin and cNFs host distinct T cell populations, whereas no dominant cNF-specific T cell clones were detected. Unique T cell clones were fewer in cNFs than in skin, and mass spectrometry suggested lower expression of proteins related to T cell-mediated immunity in cNFs than in skin. CD163-positive cells, suggestive of M2 macrophages, were abundant in cNFs. Human cNFs have substantial T cell and macrophage populations that may be tumor-specific.

CTLA-4 Checkpoint Inhibition Improves Sepsis Survival in Alcohol-Exposed Mice

Chronic alcohol use increases morbidity and mortality in the setting of sepsis. Both chronic alcohol use and sepsis are characterized by immune dysregulation, including overexpression of T cell coinhibitory molecules. We sought to characterize the role of CTLA-4 during sepsis in the setting of chronic alcohol exposure using a murine model of chronic alcohol ingestion followed by cecal ligation and puncture. Results indicated that CTLA-4 expression is increased on CD4+ T cells isolated from alcohol-drinking septic mice as compared with either alcohol-drinking sham controls or water-drinking septic mice. Moreover, checkpoint inhibition of CTLA-4 improved sepsis survival in alcohol-drinking septic mice, but not water-drinking septic mice. Interrogation of the T cell compartments in these animals following pharmacologic CTLA-4 blockade, as well as following conditional Ctla4 deletion in CD4+ T cells, revealed that CTLA-4 deficiency promoted the activation and proliferation of effector regulatory T cells and the generation of conventional effector memory CD4+ T cells. These data highlight an important role for CTLA-4 in mediating mortality during sepsis in the setting of chronic alcohol exposure and may inform future approaches to develop targeted therapies for this patient population.

Regulatory T cells in dominant immunologic tolerance

Regulatory T cells expressing the transcription factor forkhead box protein 3 mediate peripheral immune tolerance both to self-antigens and to the commensal flora. Their defective function due to inborn errors of immunity or acquired insults is associated with a broad range of autoimmune and immune dysregulatory diseases. Although their function in suppressing autoimmunity and enforcing commensalism is established, a broader role for regulatory T cells in tissue repair and metabolic regulation has emerged, enabled by unique programs of tissue adaptability and specialization. In this review, we focus on the myriad roles played by regulatory T cells in immunologic tolerance and host homeostasis and the potential to harness these cells in novel therapeutic approaches to human diseases.

Helios as a Potential Biomarker in Systemic Lupus Erythematosus and New Therapies Based on Immunosuppressive Cells

The Helios protein (encoded by the IKZF2 gene) is a member of the Ikaros transcription family and it has recently been proposed as a promising biomarker for systemic lupus erythematosus (SLE) disease progression in both mouse models and patients. Helios is beginning to be studied extensively for its influence on the T regulatory (Treg) compartment, both CD4+ Tregs and KIR+/Ly49+ CD8+ Tregs, with alterations to the number and function of these cells correlated to the autoimmune phenomenon. This review analyzes the most recent research on Helios expression in relation to the main immune cell populations and its role in SLE immune homeostasis, specifically focusing on the interaction between T cells and tolerogenic dendritic cells (tolDCs). This information could be potentially useful in the design of new therapies, with a particular focus on transfer therapies using immunosuppressive cells. Finally, we will discuss the possibility of using nanotechnology for magnetic targeting to overcome some of the obstacles related to these therapeutic approaches.

Human HLA-DR+CD27+ regulatory T cells show enhanced antigen-specific suppressive function

Regulatory T cells (Tregs) have potential for the treatment of autoimmune diseases and graft rejection. Antigen specificity and functional stability are considered critical for their therapeutic efficacy. In this study, expansion of human Tregs in the presence of porcine PBMCs (xenoantigen-expanded Tregs, Xn-Treg) allowed the selection of a distinct Treg subset, coexpressing the activation/memory surface markers HLA-DR and CD27 with enhanced proportion of FOXP3+Helios+ Tregs. Compared with their unsorted and HLA-DR+CD27+ double-positive (DP) cell-depleted Xn-Treg counterparts, HLA-DR+CD27+ DP-enriched Xn-Tregs expressed upregulated Treg function markers CD95 and ICOS with enhanced suppression of xenogeneic but not polyclonal mixed lymphocyte reaction. They also had less Treg-specific demethylation in the region of FOXP3 and were more resistant to conversion to effector cells under inflammatory conditions. Adoptive transfer of porcine islet recipient NOD/SCID IL2 receptor γ-/- mice with HLA-DR+CD27+ DP-enriched Xn-Tregs in a humanized mouse model inhibited porcine islet graft rejection mediated by 25-fold more human effector cells. The prolonged graft survival was associated with enhanced accumulation of FOXP3+ Tregs and upregulated expression of Treg functional genes, IL10 and cytotoxic T lymphocyte antigen 4, but downregulated expression of effector Th1, Th2, and Th17 cytokine genes, within surviving grafts. Collectively, human HLA-DR+CD27+ DP-enriched Xn-Tregs expressed a specific regulatory signature that enabled identification and isolation of antigen-specific and functionally stable Tregs with potential as a Treg-based therapy.

Pien Tze Huang alleviates Concanavalin A-induced autoimmune hepatitis by regulating intestinal microbiota and memory regulatory T cells

BACKGROUND

Traditional Chinese medicine has used the drug Pien Tze Huang (PTH), a classic prescription, to treat autoimmune hepatitis (AIH). However, the precise mode of action is still unknown.

AIM

To investigate the mechanism of PTH in an AIH mouse model by determining the changes in gut microbiota structure and memory regulatory T (mTreg) cells functional levels.

METHODS

Following induction of the AIH mouse model induced by Concanavalin A (Con A), prophylactic administration of PTH was given for 10 d. The levels of mTreg cells were measured by flow cytometry, and intestinal microbiota was analyzed by 16S rRNA analysis, while western blotting was used to identify activation of the toll-like receptor (TLR)2, TLR4/nuclear factor-κB (NF-κB), and CXCL16/CXCR6 signaling pathways.

RESULTS

In the liver of mice with AIH, PTH relieved the pathological damage and reduced the numbers of T helper type 17 cells and interferon-γ, tumor necrosis factor-alpha, interleukin (IL)-1β, IL-2, IL-6, and IL-21 expression. Simultaneously, PTH stimulated the abundance of helpful bacteria, promoted activation of the TLR2 signal, which may enhance Treg/mTreg cells quantity to produce IL-10, and suppressed activation of the TLR4/NF-κB and CXCL16/CXCR6 signaling pathways.

CONCLUSION

PTH regulates intestinal microbiota balance and restores mTreg cells to alleviate experimental AIH, which is closely related to the TLR/CXCL16/CXCR6/NF-κB signaling pathway.

Resident regulatory T cells reflect the immune history of individual lymph nodes

Regulatory T cells (Tregs) are present in lymphoid and nonlymphoid tissues where they restrict immune activation, prevent autoimmunity, and regulate inflammation. Tregs in nonlymphoid tissues are typically resident, whereas those in lymph nodes (LNs) are considered to recirculate. However, Tregs in LNs are not a homogenous population, and circulation kinetics of different Treg subsets are poorly characterized. Furthermore, whether Tregs can acquire memory T cell properties and persist for extended periods after their activation in LNs is unclear. Here, we used in situ labeling with a stabilized photoconvertible protein to uncover turnover rates of Tregs in LNs in vivo. We found that, whereas most Tregs in LNs recirculate, 10 to 20% are memory-like resident cells that remain in their respective LNs for weeks to months. Single-cell RNA sequencing revealed that LN-resident cells are a functionally and ontogenetically heterogeneous population and share the same core residency gene signature with conventional CD4+ and CD8+ T cells. Resident cells in LNs did not actively proliferate and did not require continuous T cell receptor (TCR) signaling for their residency. However, resident and circulating Tregs had distinct TCR repertoires, and each LN contained exclusive clonal subpopulations of resident Tregs. Our results demonstrate that, similar to conventional T cells, Tregs can form resident memory-like populations in LNs after adaptive immune responses. Specific and local suppression of immune responses by resident Tregs in draining LNs might provide previously unidentified therapeutic opportunities for the treatment of local chronic inflammatory conditions.

Cell-based therapies for the treatment of rheumatoid arthritis

Autoimmune diseases, including rheumatoid arthritis that is the most prevalent rheumatic autoimmune disorder, affect autologous connective tissues caused by the breakdown of the self-tolerance mechanisms of the immune system. During the last two decades, cell-based therapy, including stem cells and none-stem cells has been increasingly considered as a therapeutic option in various diseases. This is partly due to the unique properties of stem cells that divide and differentiate from the specialized cells in the damaged tissue. Moreover, stem cells and none-stem cells, impose immunomodulatory properties affecting the diseases caused by immunological abnormalities such as rheumatic autoimmune disorders. In the present review, the efficacy of cell-based therapy with four main types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, embryonic stem cells, and human amniotic membrane cells, as well as none-stem cells, including regulatory T cells, chimeric antigen receptor T cells, and tolerogenic dendritic cells will be evaluated. Moreover, other related issues, including safety, changes in immunological parameters, suitable choice of stem cell and none-stem cell origin, conditioning regimen, limitations, and complications will be discussed.

Memory regulatory T cells in pregnancy

Pregnancy requires the process of maternal immune tolerance to semi-allogeneic embryos. In contrast, an overreactive maternal immune system to embryo-specific antigens is likely to result in the rejection of embryos while damaging the invading placenta, such that the likelihood of adverse pregnancy outcomes can be increased. Regulatory T cells (Tregs) are capable of suppressing excessive immune responses and regulating immune homeostasis. When stimulating Tregs, specific antigens will differentiate into memory Tregs with long-term survival and rapid and powerful immune regulatory ability. Immunomodulatory effects mediated by memory Tregs at the maternal-fetal interface take on critical significance in a successful pregnancy. The impaired function of memory Tregs shows a correlation with various pregnancy complications (e.g., preeclampsia, gestational diabetes mellitus, and recurrent pregnancy losses). However, the differentiation process and characteristics of memory Tregs, especially their role in pregnancy, remain unclear. In this study, a review is presented in terms of memory Tregs differentiation and activation, the characteristics of memory Tregs and their role in pregnancy, and the correlation between memory Tregs and pregnancy complications. Furthermore, several potential therapeutic methods are investigated to restore the function of memory Tregs in accordance with immunopathologies arising from memory Tregs abnormalities and provide novel targets for diagnosing and treating pregnancy-associated diseases.

The Reciprocal Interplay between Infections and Inherited Metabolic Disorders

Infections represent the main cause of acute metabolic derangements and/or the worsening of the clinical course of many inherited metabolic disorders (IMDs). The basic molecular mechanisms behind the role of infections in these conditions have not been completely clarified. This review points out the different mechanisms behind the relationship between IMDs and infections, providing an overview of this still-under-investigated area. Classically, infections have been considered as the consequence of a compromised immune system due to a biochemical defect of energy production. An adjunctive pathogenetic mechanism is related to a genetically altered protein-attached glycans composition, due to congenital glycosilation defects. In addition, a dietary regimen with a reduced intake of both micro- and macronutrients can potentially compromise the ability of the immune system to deal with an infection. There is recent pre-clinical evidence showing that during infections there may be a disruption of substrates of various metabolic pathways, leading to further cellular metabolic alteration. Therefore, infective agents may affect cellular metabolic pathways, by mediation or not of an altered immune system. The data reviewed here strongly suggest that the role of infections in many types of IMDs deserves greater attention for a better management of these disorders and a more focused therapeutic approach.

"IL-2 immunotherapy for targeting regulatory T cells in autoimmunity"

FOXP3+ regulatory T cells (Treg) are indispensable for immune homoeostasis and for the prevention of autoimmune diseases. Interleukin-2 (IL-2) signalling is critical in all aspects of Treg biology. Consequences of defective IL-2 signalling are insufficient numbers or dysfunction of Treg and hence autoimmune disorders in human and mouse. The restoration and maintenance of immune homoeostasis remain central therapeutic aims in the field of autoimmunity. Historically, broadly immunosuppressive drugs with serious side-effects have been used for the treatment of autoimmune diseases or prevention of organ-transplant rejection. More recently, ex vivo expanded or in vivo stimulated Treg have been shown to induce effective tolerance in clinical trials supporting the clinical benefit of targeting natural immunosuppressive mechanisms. Given the central role of exogenous IL-2 in Treg homoeostasis, a new and promising focus in drug development are IL-2-based approaches for in vivo targeted expansion of Treg or for enhancement of their suppressive activity. In this review, we summarise the role of IL-2 in Treg biology and consequences of dysfunctional IL-2 signalling pathways. We then examine evidence of efficacy of IL-2-based biological drugs targeting Treg with specific focus on therapeutic candidates in clinical trials and discuss their limitations.

Ellagic acid effects on disease severity, levels of cytokines and T-bet, RORγt, and GATA3 genes expression in multiple sclerosis patients: a multicentral-triple blind randomized clinical trial

Background

Multiple sclerosis (MS) is a chronic autoimmune disease. Ellagic acid is a natural polyphenol and affects the fate of neurons through its anti-inflammatory and antioxidant properties. The present study aimed to investigate ellagic acid effects on disease severity, the expression of involved genes in the pathogenesis of MS, and the levels of related cytokines.

Methods

The present study was a triple-blind clinical trial. Eligible patients were randomly assigned to two groups: Ellagic acid (25 subjects) for 12 weeks, receiving 180 mg of Ellagic acid (Axenic, Australia) and the control group (25 subjects) receiving a placebo, before the main meals. Before and after the study, the data including general information, foods intake, physical activity, anthropometric data, expanded disability status scale (EDSS), general health questionnaire (GHQ) and pain rating index (PRI), fatigue severity scale (FSS) were assessed, as well as serum levels of interferon-gamma (IFNγ), interleukin-17 (IL-17), interleukin-4 (IL-4) and transforming growth factor-beta (TGF-β), nitric-oxide (NO) using enzyme-linked immunoassay (ELISA) method and expression of T-box transcription factor (Tbet), GATA Binding Protein 3 (GATA3), retinoic acid-related orphan receptor-γt (RORγt) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were determined using Real-Time Quantitative Reverse Transcription PCR (RT-qPCR) method.

Findings

Ellagic acid supplementation led to a reduction in IFNγ, IL-17, NO and increased IL-4 in the ellagic acid group, however in the placebo group no such changes were observed (-24.52 ± 3.79 vs. -0.05 ± 0.02, p < 0.01; -5.37 ± 0.92 vs. 2.03 ± 1.03, p < 0.01; -18.03 ± 1.02 vs. -0.06 ± 0.05, p < 0.01, 14.69 ± 0.47 vs. -0.09 ± 0.14, p < 0.01, respectively). Ellagic acid supplementation had no effect on TGF-β in any of the study groups (p > 0.05). Also, the Tbet and RORγt genes expression decreased, and the GATA3 gene expression in the group receiving ellagic acid compared to control group significantly increased (0.52 ± 0.29 vs. 1.51 ± 0.18, p < 0.01, 0.49 ± 0.18 vs. 1.38 ± 0.14, p < 0.01, 1.71 ± 0.39 vs. 0.27 ± 0.10, p < 0.01). Also, ellagic acid supplementation led to significant decrease in EDSS, FSS and GHQ scores (p < 0.05), and no significant changes observed in PRI score (p > 0.05).

Conclusion

Ellagic acid supplementation can improve the health status of MS patients by reduction of the inflammatory cytokines and Tbet and RORγt gene expression, and increment of anti-inflammatory cytokines and GATA3 gene expression.Clinical trial registration: (https://en.irct.ir/trial/53020), IRCT20120415009472N22.

Contribution of viral and bacterial infections to senescence and immunosenescence

Cellular senescence is a key biological process characterized by irreversible cell cycle arrest. The accumulation of senescent cells creates a pro-inflammatory environment that can negatively affect tissue functions and may promote the development of aging-related diseases. Typical biomarkers related to senescence include senescence-associated β-galactosidase activity, histone H2A.X phosphorylation at serine139 (γH2A.X), and senescence-associated heterochromatin foci (SAHF) with heterochromatin protein 1γ (HP-1γ protein) Moreover, immune cells undergoing senescence, which is known as immunosenescence, can affect innate and adaptative immune functions and may elicit detrimental effects over the host's susceptibility to infectious diseases. Although associations between senescence and pathogens have been reported, clear links between both, and the related molecular mechanisms involved remain to be determined. Furthermore, it remains to be determined whether infections effectively induce senescence, the impact of senescence and immunosenescence over infections, or if both events coincidently share common molecular markers, such as γH2A.X and p53. Here, we review and discuss the most recent reports that describe cellular hallmarks and biomarkers related to senescence in immune and non-immune cells in the context of infections, seeking to better understand their relationships. Related literature was searched in Pubmed and Google Scholar databases with search terms related to the sections and subsections of this review.

T-cell immunity to SARS-CoV-2: what if the known best is not the optimal course for the long run? Adapting to evolving targets

Humanity did surprisingly well so far, considering how unprepared it was to respond to the coronavirus disease 2019 (COVID-19) threat. By blending old and ingenious new technology in the context of the accumulated knowledge on other human coronaviruses, several vaccine candidates were produced and tested in clinical trials in record time. Today, five vaccines account for the bulk of the more than 13 billion doses administered worldwide. The ability to elicit biding and neutralizing antibodies most often against the spike protein is a major component of the protection conferred by immunization but alone it is not enough to limit virus transmission. Thus, the surge in numbers of infected individuals by newer variants of concern (VOCs) was not accompanied by a proportional increase in severe disease and death rate. This is likely due to antiviral T-cell responses, whose evasion is more difficult to achieve. The present review helps navigating the very large literature on T cell immunity induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination. We examine the successes and shortcomings of the vaccinal protection in the light of the emergence of VOCs with breakthrough potential. SARS-CoV-2 and human beings will likely coexist for a long while: it will be necessary to update existing vaccines to improve T-cell responses and attain better protection against COVID-19.

CD4+ T cell memory

Specialized subpopulations of CD4+ T cells survey major histocompatibility complex class II-peptide complexes to control phagosomal infections, help B cells, regulate tissue homeostasis and repair or perform immune regulation. Memory CD4+ T cells are positioned throughout the body and not only protect the tissues from reinfection and cancer, but also participate in allergy, autoimmunity, graft rejection and chronic inflammation. Here we provide updates on our understanding of the longevity, functional heterogeneity, differentiation, plasticity, migration and human immunodeficiency virus reservoirs as well as key technological advances that are facilitating the characterization of memory CD4+ T cell biology.

Antigen-specific T cell balance reveals Why patients with atopic dermatitis fail to achieve immune tolerance

The number of regulatory T cells (Tregs) and how they behave in the pathogenesis of atopic dermatitis (AD) are still controversial. We identified and quantified Tregs, mite-specific Tregs, and mite-specific effector T cells (Teffs) in patients with AD and healthy controls (HCs). We collected peripheral blood and analyzed the cells using flow cytometry after stimulation with mite antigens. Mite-specific Tregs and mite-specific Teffs were recognized by the expression of CD137 and CD154, respectively. Patients with AD had more Tregs than HCs; however, when focusing on a single antigen, the ratio of mite-specific Tregs/Teffs was lower in patients with AD than in HCs. Furthermore, the mite-specific Teffs in patients with AD were more likely to produce proinflammatory cytokines interleukin (IL)-4 and IL-13. This Teff-dominant imbalance is thought to be the cause of development of atopic status in patients with AD without immune tolerance.

Altered subgroups of regulatory T cells in patients with primary Sjögren's syndrome

Primary Sjögren syndrome (pSS) is a systemic autoimmune inflammatory disease. Up to now, the role of regulatory T cells (Tregs) and their subgroups in pSS is still in controversial. In this study we tried to elucidate the roles of Tregs and its subgroups in pSS. Total 43 pSS patients and 23 health persons as control were enrolled in this study. We grouped the pSS patients according to the anti-SSa/SSb and the EULAR Sjögren's syndrome disease activity index (ESSDAI). Among the 43 pSS patients, 14 patients were followed after treatment. The percentage of rTregs (resting Treg cells) among Tregs was increased in the pSS group, and decreased after treatment. In the high disease activity subpopulation (ESSDAI ≥ 5), the percentage of rTregs among Tregs decreased after treatment. On the contrary, the percentage of aTregs (activated Treg cells) increased after treatment. It was in an inverse correlation between the percentage of aTreg and rTreg in pSS patients. The Tregs are co-cultured with responder T cells. Tregs from pSS patients showed poorer proliferation inhibitory function. Our results show that the percentages of Tregs and their subgroups altered in pSS patients. The percentage of aTreg and the percentage of rTreg have an inverse correlation in pSS patients. Compared to the control group, the percentage of rTregs among Tregs was increased in the pSS patients and decreased after the treatment. Our study also showed that The Tregs from pSS patients may have poorer inhibitory functions.

Infections after organ transplantation and immune response

Organ transplantation has provided another chance of survival for end-stage organ failure patients. Yet, transplant rejection is still a main challenging factor. Immunosuppressive drugs have been used to avoid rejection and suppress the immune response against allografts. Thus, immunosuppressants increase the risk of infection in immunocompromised organ transplant recipients. The infection risk reflects the relationship between the nature and severity of immunosuppression and infectious diseases. Furthermore, immunosuppressants show an immunological impact on the genetics of innate and adaptive immune responses. This effect usually reactivates the post-transplant infection in the donor and recipient tissues since T-cell activation has a substantial role in allograft rejection. Meanwhile, different infections have been found to activate the T-cells into CD₄⁺ helper T-cell subset and CD₈⁺ cytotoxic T-lymphocyte that affect the infection and the allograft. Therefore, the best management and preventive strategies of immunosuppression, antimicrobial prophylaxis, and intensive medical care are required for successful organ transplantation. This review addresses the activation of immune responses against different infections in immunocompromised individuals after organ transplantation.

Infection induces tissue-resident memory NK cells that safeguard tissue health

Tissue health is dictated by the capacity to respond to perturbations and then return to homeostasis. Mechanisms that initiate, maintain, and regulate immune responses in tissues are therefore essential. Adaptive immunity plays a key role in these responses, with memory and tissue residency being cardinal features. A corresponding role for innate cells is unknown. Here, we have identified a population of innate lymphocytes that we term tissue-resident memory-like natural killer (NKRM) cells. In response to murine cytomegalovirus infection, we show that circulating NK cells were recruited in a CX3CR1-dependent manner to the salivary glands where they formed NKRM cells, a long-lived, tissue-resident population that prevented autoimmunity via TRAIL-dependent elimination of CD4+ T cells. Thus, NK cells develop adaptive-like features, including long-term residency in non-lymphoid tissues, to modulate inflammation, restore immune equilibrium, and preserve tissue health. Modulating the functions of NKRM cells may provide additional strategies to treat inflammatory and autoimmune diseases.

The effect of probiotics on immune responses and their therapeutic application: A new treatment option for multiple sclerosis

Multiple sclerosis (MS) is known as a chronic inflammatory disease (CID) that affects the central nervous system and leads to nerve demyelination. However, the exact cause of MS is unknown, but immune system regulation and inhibiting the function of inflammatory pathways may have a beneficial effect on controlling and improving the disease. Studies show that probiotics can alter the gut microbiome, thereby improving and affecting the immune system and inflammatory responses in patients with MS. The results show that probiotics have a good effect on the recovery of patients with MS in humans and animals. The present study investigated the effect of probiotics and possible therapeutic mechanisms of probiotics on immune cells and inflammatory cytokines. This review article showed that probiotics could improve immune cells and inflammatory cytokines in patients with MS and can play an effective role in disease management and control.

Osteopontin and Regulatory T Cells in Effector Phase of Allergic Contact Dermatitis

Studies have shown that osteopontin (OPN) and regulatory T cells play a role in allergic contact dermatitis (ACD), but the mechanisms responsible for their function are poorly understood. The study aimed to determine CD4 T lymphocytes producing intracellular osteopontin (iOPN T cells) and assess the selected T lymphocyte subsets including regulatory T cells in the blood of patients with ACD. Twenty-six patients with a disseminated form of allergic contact dermatitis and 21 healthy controls were enrolled in the study. Blood samples were taken twice: in the acute phase of the disease and during remission. The samples were analyzed by the flow cytometry method. Patients with acute ACD showed significantly higher percentage of iOPN T cells compared with healthy controls which persisted during remission. An increase in the percentage of CD4CD25 and a reduced percentage of regulatory T lymphocytes (CD4CD25highCD127low) were also found in the patients with acute stage of ACD. The percentage of CD4CD25 T lymphocytes showed a positive correlation with the EASI index. The increase in the iOPN T cells can indicate their participation in acute ACD. The decreased percentage of regulatory T lymphocytes in the acute stage of ACD may be related to the transformation of Tregs into CD4CD25 T cells. It may also indicate their increased recruitment to the skin. The positive correlation between the percentage of CD4CD25 lymphocytes and the EASI index may be indirect evidence for the importance of activated lymphocytes-CD4CD25 in addition to CD8 lymphocytes as effector cells in ACD.

Do Treg Speed Up with CARs? Chimeric Antigen Receptor Treg Engineered to Induce Transplant Tolerance

Adoptive transfer of regulatory T cells (Treg) can induce transplant tolerance in preclinical models by suppressing alloantigen-directed inflammatory responses; clinical translation was so far hampered by the low abundance of Treg with allo-specificity in the peripheral blood. In this situation, ex vivo engineering of Treg with a T-cell receptor (TCR) or chimeric antigen receptor (CAR) provides a cell population with predefined specificity that can be amplified and administered to the patient. In contrast to TCR-engineered Treg, CAR Treg can be redirected toward a broad panel of targets in an HLA-unrestricted fashion' making these cells attractive to provide antigen-specific tolerance toward the transplanted organ. In preclinical models, CAR Treg accumulate and amplify at the targeted transplant, maintain their differentiated phenotype, and execute immune repression more vigorously than polyclonal Treg. With that, CAR Treg are providing hope in establishing allospecific, localized immune tolerance in the long term' and the first clinical trials administering CAR Treg for the treatment of transplant rejection are initiated. Here, we review the current platforms for developing and manufacturing alloantigen-specific CAR Treg and discuss the therapeutic potential and current hurdles in translating CAR Treg into clinical exploration.

Characterization of Regulatory T Cells in Patients Infected by Leishmania Infantum

High IL-10 levels are pivotal to parasite survival in visceral leishmaniasis (VL). Antigenic stimuli induce IL-10 expression and release of adenosine by CD39/CD73. Due their intrinsic ability to express IL-10 and produce adenosine from extracellular ATP, we evaluated the IL-10, CD39, and CD73 expression by Regulatory T cells (Treg) correlated with VL pathology. Using flow cytometry, Treg cells was analyzed in peripheral blood samples from VL patients (in the presence and absence of Leishmania infantum soluble antigen (SLA)) and healthy individuals (negative endemic control-NEC group), without any treatment. Additionally, IL-10 levels in leukocytes culture supernatant were measured in all groups by ELISA assay. VL patients presented more Treg frequency than NEC group, independently of stimulation. ELISA results demonstrated that SLA induced higher IL-10 expression in the VL group. However, the NEC group had a higher Treg IL-10⁺ compared to the VL group without stimulation and SLA restored the IL-10 in Treg. Additionally, an increase in Treg CD73⁺ in the VL group independently of stimuli compared to that in the NEC group was observed. We suggest that Treg are not the main source of IL-10, while the CD73 pathway may be an attempt to modulate the exacerbation of immune response in VL disease.

Soluble factors from TLR4- or TCR-activated cells contribute to stability of the resting phenotype and increase the expression of CXCR4 of human memory CD4 T cells

It has been proposed that cytokines can induce activation of resting T cells in an antigen-independent manner. However, experimental conditions have included the use of fetal serum and nanogram concentrations of added cytokines. To evaluate the effect of cytokines and chemokines generated by activated immune cells on the phenotypic profile of human memory CD4 T cells, the cells were cultured in FBS-free conditions in the presence of IL-15 and 5% of hAB serum and incubated with conditioned medium (CM) obtained from PBMC activated through the TCR using anti-CD3/CD28/CD2 antibodies (TCR-CM) or through TLR4 using bacterial LPS (TLR4-CM). Cytokines and chemokines present in the CMs were evaluated by ProcartaPlex immunoassay. Cell viability, proliferation, and surface markers were determined by flow cytometry on day 2, 5, and 8 of culture. Cell viability was maintained by TLR4-CM plus IL-15 for 8 days but decreased in the presence of the TCR-CM plus IL-15. In combination with IL-15, the TLR4-CM, but not the TCR-CM, maintained the expression of CD3 and CD4 stable. Both conditions stabilized the expression of CD45RO and CCR5. Thus, the TLR4-CM better supported the viability and stability of the memory phenotype. None of the CMs induced proliferation or expression of activation markers; however, they induced an increased expression of CXCR4. This study indicates that resting memory CD4 T cells are not activated by, but may be sensitive to soluble factors produced by antigen or PAMP-stimulated cells, which may contribute to their homeostasis and favor the CXCR4 expression.

A scoping review of regulatory T cell dynamics in convalescent COVID-19 patients - indications for their potential involvement in the development of Long COVID?

Background

Recovery from coronavirus disease 2019 (COVID-19) can be impaired by the persistence of symptoms or new-onset health complications, commonly referred to as Long COVID. In a subset of patients, Long COVID is associated with immune system perturbations of unknown etiology, which could be related to compromised immunoregulatory mechanisms.

Objective

The objective of this scoping review was to summarize the existing literature regarding the frequency and functionality of Tregs in convalescent COVID-19 patients and to explore indications for their potential involvement in the development of Long COVID.

Design

A systematic search of studies investigating Tregs during COVID-19 convalescence was conducted on MEDLINE (via Pubmed) and Web of Science.

Results

The literature search yielded 17 relevant studies, of which three included a distinct cohort of patients with Long COVID. The reviewed studies suggest that the Treg population of COVID-19 patients can reconstitute quantitatively and functionally during recovery. However, the comparison between recovered and seronegative controls revealed that an infection-induced dysregulation of the Treg compartment can be sustained for at least several months. The small number of studies investigating Tregs in Long COVID allowed no firm conclusions to be drawn about their involvement in the syndrome's etiology. Yet, even almost one year post-infection Long COVID patients exhibit significantly altered proportions of Tregs within the CD4+ T cell population.

Conclusions

Persistent alterations in cell frequency in Long COVID patients indicate that Treg dysregulation might be linked to immune system-associated sequelae. Future studies should aim to address the association of Treg adaptations with different symptom clusters and blood parameters beyond the sole quantification of cell frequencies while adhering to consensualized phenotyping strategies.

Adaptive discrimination between harmful and harmless antigens in the immune system by predictive coding

The immune system discriminates between harmful and harmless antigens based on past experiences; however, the underlying mechanism is largely unknown. From the viewpoint of machine learning, the learning system predicts the observation and updates the prediction based on prediction error, a process known as "predictive coding." Here, we modeled the population dynamics of T cells by adopting the concept of predictive coding; conventional and regulatory T cells predict the antigen concentration and excessive immune response, respectively. Their prediction error signals, possibly via cytokines, induce their differentiation to memory T cells. Through numerical simulations, we found that the immune system identifies antigen risks depending on the concentration and input rapidness of the antigen. Further, our model reproduced history-dependent discrimination, as in allergy onset and subsequent therapy. Taken together, this study provided a novel framework to improve our understanding of how the immune system adaptively learns the risks of diverse antigens.

The characteristics of antigenic specificity of memory regulatory t cells in women with unexplained recurrent pregnancy loss

Regulatory T cells (Tregs) proliferate after encountering the fetal antigen, which plays an important role in maintaining maternal-fetal tolerance. Activated Tregs increase number and function after antigen encounter and develop memory. Upon subsequent antigen exposure, Treg cells re-expand more rapidly. However, the characteristics of memory regulatory T cells (mTregs) during normal pregnancy and unexplained recurrent pregnancy loss (URPL) have not been elucidated well. In this study, we analyzed the proportion of Tregs and mTregs in the peripheral blood and their surface expression of PD-1, CCR6, and HLA-G in normal non-pregnant (n = 20) and pregnant (n = 20) women, and non-pregnant (n = 20) and pregnant URPL (n = 20) women. We found that the proportions of mTregs in lymphocytes, CD3⁺ T cells, CD4⁺ T cells, and Tregs were lower in pregnant URPL patients than in normal pregnant women. The proportions of CD4⁺CD45RO⁺ Th cells in lymphocytes, CD3⁺ T, and CD4⁺ T cells in the pregnant URPL group were the highest among the four groups (P < 0.05). There were no significant differences among the other three groups (P > 0.05). The proportions of CD4⁺/CCR6⁺/mTregs, CD4⁺/PD^-1⁺/mTregs, CD4⁺/HLA-G^+/mTregs were significantly lower in the non-pregnant normal group and non-pregnant URPL group than in normal pregnant group and pregnant URPL group (P < 0.05, respectively). The proportions of CD4⁺/CCR6⁺ mTregs, CD4⁺/PD-1⁺/mTregs^, CD4^+/HLA-G⁺/mTregs were lower in pregnant URPL group than in normal pregnant group (P < 0.05, respectively). These findings indicate that fetal antigen-specific mTregs play an important role in pregnancy maintenance, and the dysregulation of mTreg may contribute to URPL.

Recent highlights in the immunomodulatory aspects of Treg cell-derived extracellular vesicles: special emphasis on autoimmune diseases and transplantation

In order to maintain immunological tolerance to self and non-self antigens, one’s T regulatory (Treg) cells play a critical role in the regulation of detrimental inflammation. Treg cells inhibit the immune system in a variety of ways, some of which are contact-dependent and the others are soluble factors. Extracellular vesicles (EVs) are mainly secretory membrane structures that play a pivotal role in intercellular communication in both the local and systemic environments, enabling the transport of proteins, lipids, and nucleic acids between immune and non-immune cells. A number of studies have shown that Treg-derived EVs are specially formulated intercellular exchanging devices capable of regulating immunological responses by producing a cell-free tolerogenic milieu. Some of the processes suggested include miRNA-induced gene shutdown and upmodulation, surface protein activity, and enzyme transfer. Instead of being influenced by external circumstances like Tregs, exosomes’ cohesive structure allows them to transmit their charge intact across the blood–brain barrier and deliver it to the target cell with particular receptors. These properties have resulted in the use of Treg-derived EVs' immunomodulatory effects moving beyond laboratory research and into preclinical applications in animal models of a variety of inflammatory, autoimmune, and transplant rejection disorders. However, insufficient evidence has been produced to permit enrollment in human clinical studies. As such, we begin our research by introducing the most potent immunosuppressive elements discovered in Treg-derived EVs elucidating likely mechanisms of action in inhibiting immunological responses. Following that, we address recent research on the potential of suppressive EVs to regulate autoimmune inflammatory responses and improve tissue transplant survival.

Peripheral Blood T-lymphocyte Phenotypes in Mother-Child Pairs Stratified by the Maternal HPV Status: Persistent HPV16 vs. HPV-Negative: A Case-Control Study

Only few studies exist on the phenotype distribution of peripheral blood lymphocytes concerning persistent oral HPV infection. T-lymphocyte subsets were phenotyped in women who had persistent genital or oral HPV16 infection, using HPV-negative women as a reference group. A subset of 42 mothers and their children (n = 28), were stratified into two groups according to the mothers' HPV status. PBMCs from previously cryopreserved venous samples were immunophenotyped by flow cytometry. Proportions of the CD4⁺ or CD8⁺ lymphocytes by their immunophenotype subsets were compared between HPV-positive and -negative mothers and their children. The mean rank distribution of CD8⁺ memory cells was significantly higher among mothers with persistent genital HPV16 infection. The median levels of both the antigen-presenting CD4⁺ cells and activated CD8⁺ cells were significantly lower in mothers with persistent oral HPV16 infection. When oral and genital HPV16-persistors were analyzed as a group, a marker of terminal effector cells was significantly increased as compared to HPV-negative women. Significantly higher levels of activated CD4⁺, CD8⁺ and circulating CD8⁺ memory cells were found among children whose mothers had persistent oral HPV16 infection. Persistent HPV16 infections are associated with changes in peripheral blood T-lymphocyte subsets. The mother's persistent oral HPV16 infection possibly results in immune alterations in her offspring.

The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases

The adaptive immune system and associated inflammation are vital in surveillance and host protection against internal and external threats, but can secondarily damage host tissues. The central nervous system is immune-privileged and largely protected from the circulating inflammatory pathways. However, T cell involvement and the disruption of the blood-brain barriers have been linked to several neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Under normal physiological conditions, regulatory T cells (Treg cells) dampen the inflammatory response of effector T cells. In the pathological states of many neurodegenerative disorders, the ability of Treg cells to mitigate inflammation is reduced, and a pro-inflammatory environment persists. This perspective review provides current knowledge on the roles of T cell subsets (e.g., effector T cells, Treg cells) in neurodegenerative and ocular diseases, including uveitis, diabetic retinopathy, age-related macular degeneration, and glaucoma. Many neurodegenerative and ocular diseases have been linked to immune dysregulation, but the cellular events and molecular mechanisms involved in such processes remain largely unknown. Moreover, the role of T cells in ocular pathologies remains poorly defined and limited literature is available in this area of research. Adoptive transfer of Treg cells appears to be a vital immunological approach to control ocular pathologies. Similarities in T cell dysfunction seen among non-ocular neurodegenerative diseases suggest that this area of research has a great potential to develop better therapeutic agents for ocular diseases and warrants further studies. Overall, this perspective review article provides significant information on the roles of T cells in numerous ocular and non-ocular neurodegenerative diseases.

A Placebo-controlled double-blinded test of the biodiversity hypothesis of immune-mediated diseases: Environmental microbial diversity elicits changes in cytokines and increase in T regulatory cells in young children

BACKGROUND

According to the biodiversity hypothesis of immune-mediated diseases, lack of microbiological diversity in the everyday living environment is a core reason for dysregulation of immune tolerance and - eventually - the epidemic of immune-mediated diseases in western urban populations. Despite years of intense research, the hypothesis was never tested in a double-blinded and placebo-controlled intervention trial.

OBJECTIVE

We aimed to perform the first placebo-controlled double-blinded test that investigates the effect of biodiversity on immune tolerance.

METHODS

In the intervention group, children aged 3-5 years were exposed to playground sand enriched with microbially diverse soil, or in the placebo group, visually similar, but microbially poor sand colored with peat (13 participants per treatment group). Children played twice a day for 20 min in the sandbox for 14 days. Sand, skin and gut bacterial, and blood samples were taken at baseline and after 14 days. Bacterial changes were followed for 28 days. Sand, skin and gut metagenome was determined by high throughput sequencing of bacterial 16 S rRNA gene. Cytokines were measured from plasma and the frequency of blood regulatory T cells was defined as a percentage of total CD3 +CD4 + T cells.

RESULTS

Bacterial richness (P < 0.001) and diversity (P < 0.05) were higher in the intervention than placebo sand. Skin bacterial community, including Gammaproteobacteria, shifted only in the intervention treatment to resemble the bacterial community in the enriched sand (P < 0.01). Mean change in plasma interleukin-10 (IL-10) concentration and IL-10 to IL-17A ratio supported immunoregulation in the intervention treatment compared to the placebo treatment (P = 0.02). IL-10 levels (P = 0.001) and IL-10 to IL-17A ratio (P = 0.02) were associated with Gammaproteobacterial community on the skin. The change in T_reg frequencies was associated with the relative abundance of skin Thermoactinomycetaceae 1 (P = 0.002) and unclassified Alphaproteobacteria (P < 0.001). After 28 days, skin bacterial community still differed in the intervention treatment compared to baseline (P < 0.02).

CONCLUSIONS

This is the first double-blinded placebo-controlled study to show that daily exposure to microbial biodiversity is associated with immune modulation in humans. The findings support the biodiversity hypothesis of immune-mediated diseases. We conclude that environmental microbiota may contribute to child health, and that adding microbiological diversity to everyday living environment may support immunoregulation.

Lkb1 aggravates diffuse large B-cell lymphoma by promoting the function of Treg cells and immune escape

Background

Regulatory T cells (Tregs) induce immune responses and may contribute to immune escape in tumors. Accumulation of Tregs in tumors represents a critical barrier to anti-tumor immunity and immunotherapy. However, conflicting results describing the role of Tregs in lymphoma warrant further investigation. The precise features and mechanisms underlying the alteration in Tregs in diffuse large B-cell lymphoma (DLBCL) are not well understood yet. In this study, we analyzed the mechanism underlying the observed alterations in Tregs in DLBCL and examined the effect of Lkb1 expression on the immunosuppressive function of human Tregs.

Methods

Flow cytometry and immunofluorescence were used to analyze the proportion of Tregs and effector Tregs in the peripheral blood and lymph nodes of patients with DLBCL and control group. In vitro culture assays were used to analyze the immunosuppressive function of Tregs in the two groups. Transcriptome sequencing was performed to analyze the differentially expressed genes in the two groups, and the transcription level and protein expression of Lkb1 in the two groups were detected using RT-PCR and WES microprotein technology. Lentiviral vectors were constructed to explore the functional changes of Tregs with stable upregulation and downregulation of Lkb1. Finally, a humanized murine lymphoma model was established to study the function of Lkb1 in Tregs in the pathogenesis of DLBCL.

Results

The number of Tregs was found to be dramatically increased in peripheral blood and tumor tissue in DLBCL patients compared with that in healthy controls, and decreased after treatment. Tregs from DLBCL patients exhibited multiple enhanced functions, including increased inhibition of CD8⁺cytotoxic T cells (CTL) against tumor cells, enhanced suppression of CD8⁺CTL secretion of granular enzyme, and suppression of CD8⁺CTL degranulation. Lkb1 was found to be upregulated in Tregs of DLBCL patients. Furthermore, Lkb1 contributes to Treg immunosuppressive function in DLBCL by regulating the mevalonate pathway. Finally, deletion of Lkb1 in Tregs suppressed tumor growth and promoted anti-tumor immunity in a DLBCL murine model.

Conclusions

These findings confirmed that Lkb1-regulated Tregs are critical for immune escape in DLBCL, which emphasizes that Lkb1 is a potential target for the immunotherapy of DLBCL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03588-0.

Activation Markers on B and T Cells and Immune Checkpoints in Autoimmune Rheumatic Diseases

In addition to identifying the major B- and T-cell subpopulations involved in autoimmune rheumatic diseases (ARDs), in recent years special attention has been paid to studying the expression of their activation markers and immune checkpoints (ICPs). The activation markers on B and T cells are a consequence of the immune response, and these molecules are considered as sensitive specific markers of ARD activity and as promising targets for immunotherapy. ICPs regulate the activation of the immune response by preventing the initiation of autoimmune processes, and they modulate it by reducing immune cell-induced organ and tissue damage. The article considers the possible correlation of ICPs with the activity of ARDs, the efficacy of specific ARD treatments, and the prospects for the use of activation molecules and activation/blocking ICPs for the treatment of ARDs.

Identification of a novel immune-inflammatory signature of COVID-19 infections, and evaluation of pharmacokinetics and therapeutic potential of RXn-02, a novel small-molecule derivative of quinolone

Coronavirus disease 2019 (COVID-19) is a global pandemic and respiratory infection that has enormous damage to human lives and economies. It is caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), a non-pair-stranded positive-sense RNA virus. With increasing global threats and few therapeutic options, the discovery of new potential drug targets and the development of new therapy candidates against COVID-19 are urgently needed. Based on these premises, we conducted an analysis of transcriptomic datasets from SARS-CoV-2-infected patients and identified several SARS-CoV-2 infection signatures, among which TNFRSF5/PTPRC/IDO1/MKI67 appeared to be the most pertinent signature. Subsequent integrated bioinformatics analysis identified the signature as an important immunomodulatory and inflammatory signature of SARS-CoV-2 infection. It was suggested that this gene signature mediates the interplay of immune and immunosuppressive cells leading to infiltration-exclusion of effector memory T cells in the lungs, which is of translation relevance for developing novel SARS-CoV-2 drug and vaccine candidates. Consequently, we designed and synthesized a novel small-molecule quinoline derivative (RXn-02) and evaluated its pharmacokinetics in rats, revealing a peak plasma concentration (Cmax) and time to Cmax (Tmax) of 1.756 μg/mL and 0.6 h, respectively. Values of the area under the curve (AUC) (0–24 h) and AUC (0 h∼∞) were 18.90 and 71.20 μg h/mL, respectively. Drug absorption from the various regional segments revealed that the duodenum (49.84%), jejunum (47.885%), cecum (1.82%), and ileum (0.32%) were prime sites of RXn-02 absorption. No absorption was detected from the stomach, and the least was from the colon (0.19%). Interestingly, RXn-02 exhibited in vitro antiproliferative activities against hub gene hyper-expressing cell lines; A549 (IC₅₀ = 48.1 μM), K-562 (IC₅₀ = 100 μM), and MCF7 (IC₅₀ = 0.047 μM) and against five cell lines originating from human lungs (IC₅₀ range of 33.2–69.5 μM). In addition, RXn-02 exhibited high binding efficacies for targeting the TNFRSF5/PTPRC/IDO1/MK signature with binding affinities (ΔG) of −6.6, −6.0, −9.9, −6.9 kcal/mol respectively. In conclusion, our study identified a novel signature of SARS-CoV-2 pathogenesis. RXn-02 is a drug-like candidate with good in vivo pharmacokinetics and hence possesses great translational relevance worthy of further preclinical and clinical investigations for treating SARS-CoV-2 infections.

Differentiation and homeostasis of effector Treg cells are regulated by inositol polyphosphates modulating Ca(2+) influx

Activated Foxp3⁺ regulatory T (Treg) cells differentiate into effector Treg (eTreg) cells to maintain peripheral immune homeostasis and tolerance. T cell receptor (TCR)-mediated induction and regulation of store-operated Ca²⁺ entry (SOCE) is essential for eTreg cell differentiation and function. However, SOCE regulation in Treg cells remains unclear. Here, we show that inositol polyphosphate multikinase (IPMK), which generates inositol tetrakisphosphate and inositol pentakisphosphate, is a pivotal regulator of Treg cell differentiation downstream of TCR signaling. IPMK is highly expressed in TCR-stimulated Treg cells and promotes a TCR-induced Treg cell program. IPMK-deficient Treg cells display aberrant T cell activation and impaired differentiation into RORγt⁺ Treg cells and tissue-resident Treg cells. Mechanistically, IPMK controls the generation of higher-order inositol phosphates, thereby promoting Ca²⁺ mobilization and Treg cell effector functions. Our findings identify IPMK as a critical regulator of TCR-mediated Ca²⁺ influx and highlight the importance of IPMK in Treg cell-mediated immune homeostasis.

Parity and gestational age are associated with vaginal microbiota composition in term and late term pregnancies

Background

Vaginal microbiota and its potential contribution to preterm birth is under intense research. However, only few studies have investigated the vaginal microbiota in later stages of pregnancy or at the onset of labour.

Methods

We used 16S rRNA gene amplicon sequencing to analyse cross-sectional vaginal swab samples from 324 Finnish women between 37–42 weeks of gestation, sampled before elective caesarean section, at the onset of spontaneous labour, and in pregnancies lasting ≥41 weeks of gestation. Microbiota data were combined with comprehensive clinical data to identify factors associated with microbiota variation.

Findings

Vaginal microbiota composition associated strongly with advancing gestational age and parity, i.e. presence of previous deliveries. Absence of previous deliveries was a strong predictor of Lactobacillus crispatus dominated vaginal microbiota, and the relative abundance of L. crispatus was higher in late term pregnancies, especially among nulliparous women.

Interpretation

This study identified late term pregnancy and reproductive history as factors underlying high abundance of gynaecological health-associated L. crispatus in pregnant women. Our results suggest that the vaginal microbiota affects or reflects the regulation of the duration of gestation and labour onset, with potentially vast clinical utilities. Further studies are needed to address the causality and the mechanisms on how previous labour, but not pregnancy, affects the vaginal microbiota. Parity and gestational age should be accounted for in future studies on vaginal microbiota and reproductive outcomes.

Funding

This research was supported by EU H2020 programme Sweet Crosstalk ITN (814102), Academy of Finland, State Research Funding, and University of Helsinki.

The Modulatory Effects and Targets Prediction of Herbal Medicines or Phytochemicals on Cancer Immunosurveillance

Cancer is a main life-threatening disease worldwide. Due to the adverse effects of conventional chemotherapies and radiotherapies, immunotherapy has emerged as a potent strategy to treat cancer. In cancer immunotherapy, cancer immune surveillance plays a crucial role in the cancer process, which contains various effector cells from innate and adaptive immunity. This review summarized the functions of innate and adaptive immune cells in cancer immunosurveillance and their main reported targets. Moreover, the potential targets about the modulatory effects of cancer immunosurveillance were predicted using network-based target analysis, with total predicted pathways not only reporting previously reported pathways, but also putative signaling pathways pending for investigation. In addition, the potential use of herbal medicines and their phytochemicals in the modulation of cancer immunosurveillance were also discussed. Taken together, this review paper aims to provide scientific insight into further drug development, particularly herbs, phytochemicals, and TCM formulae, in the modulatory effects of cancer immunosurveillance.

Helios Expression Is Downregulated on CD8+ Treg in Two Mouse Models of Lupus During Disease Progression

T-cell–mediated autoimmunity reflects an imbalance in this compartment that is not restored by tolerogenic immune cells, e.g., regulatory T cells or tolerogenic dendritic cells (tolDCs). Although studies into T-cell equilibrium have mainly focused on regulatory CD4⁺FoxP3⁺ T cells (CD4⁺ Tregs), recent findings on the lesser known CD8⁺ Tregs (CD44⁺CD122⁺Ly49⁺) have highlighted their non-redundant role in regulating lupus-like disease and their regulatory phenotype facilitated by the transcription factor Helios in mice and humans. However, there are still remaining questions about Helios regulation and dynamics in different autoimmune contexts. Here, we show the absence of CD8⁺ Tregs in two lupus-prone murine models: MRL/MPJ and MRL/lpr, in comparison with a non-prone mouse strain like C57BL/6. We observed that all MRL animals showed a dramatically reduced population of CD8⁺ Tregs and a greater Helios downregulation on diseased mice. Helios induction was detected preferentially on CD8⁺ T cells from OT-I mice co-cultured with tolDCs from C57BL/6 but not in MRL animals. Furthermore, the Helios profile was also altered in other relevant T-cell populations implicated in lupus, such as CD4⁺ Tregs, conventional CD4⁺, and double-negative T cells. Together, these findings could make Helios a versatile maker across the T-cell repertoire that is capable of differentiating lupus disease states.

Intestinal inflammation alters the antigen-specific immune response to a skin commensal

Resident microbes in skin and gut predominantly impact local immune cell function during homeostasis. However, colitis-associated neutrophilic skin disorders suggest possible breakdown of this compartmentalization with disease. Using a model wherein neonatal skin colonization by Staphylococcus epidermidis facilitates generation of commensal-specific tolerance and CD4⁺ regulatory T cells (Tregs), we ask whether this response is perturbed by gut inflammation. Chemically induced colitis is accompanied by intestinal expansion of S. epidermidis and reduces gut-draining lymph node (dLN) commensal-specific Tregs. It also results in reduced commensal-specific Tregs in skin and skin-dLNs and increased skin neutrophils. Increased CD4⁺ circulation between gut and skin dLN suggests that the altered cutaneous response is initiated in the colon, and resistance to colitis-induced effects in Cd4^creIl1r1^fl/fl mice implicate interleukin (IL)-1 in mediating the altered commensal-specific response. These findings provide mechanistic insight into observed connections between inflammatory skin and intestinal diseases.

Fetal‐placental antigens and the maternal immune system: Reproductive immunology comes of age

Reproductive physiology and immunology as scientific disciplines each have rich, largely independent histories. The physicians and philosophers of ancient Greece made remarkable observations and inferences to explain regeneration as well as illness and immunity. The scientific enlightenment of the renaissance and the technological advances of the past century have led to the explosion of knowledge that we are experiencing today. Breakthroughs in transplantation, immunology, and reproduction eventually culminated with Medawar’s discovery of acquired immunological tolerance, which helped to explain the transplantation success and failure. Medawar’s musings also keenly pointed out that the fetus apparently breaks these newly discovered rules, and with this, the field of reproductive immunology was launched. As a result of having stemmed from transplantation immunology, scientist still analogizes the fetus to a successful allograft. Although we now know of the fundamental differences between the two, this analogy remains a useful tool to understand how the fetus thrives despite its immunological disparity with the mother. Here, we review the history of reproductive immunology, and how major and minor histocompatibility antigens, blood group antigens, and tissue‐specific “self” antigens from the fetus and transplanted organs parallel and differ.