Tissue regulatory T cells

Bioinformatics for the Identification of STING-Related Genes in Diabetic Retinopathy

PURPOSE

Diabetic retinopathy (DR) is the most common complication of diabetes mellitus. Stimulator of interferon genes (STING) plays an important regulatory role in the transcription of several genes. This study aimed to mine and identify hub genes relevant to STING in DR.

METHODS

The STING-related genes (STING-RGs) were extracted from MSigDB database. Differentially expressed STING-RGs (DE-STING-RGs) were filtered by overlapping differentially expressed genes (DEGs) between DR and NC specimens and STING-RGs. A PPI network was established to mine hub genes. The ability of the hub genes to differentiate between DR and NC specimens was evaluated. Additionally, a ceRNA network was established to investigate the regulatory mechanisms of hub genes. Subsequently, the discrepancies in immune infiltration between DR and NC specimens were further explored. Additionally, we performed drug predictions. Finally, RT-qPCR of peripheral blood samples was used to validate the bioinformatics results.

RESULTS

A grand total of four genes (IKBKG, STAT6, NFKBIA, and FCGR2A) related to STING were identified for DR. The AUC values of all four hub genes were greater than 0.7, which indicated that the diagnostic value was acceptable. The ceRNA network contained four hub genes, 170 miRNAs, and 135 lncRNAs. In addition, immunoinfiltration analysis demonstrated that the abundance of activated B cells was notably different between the DR and NC specimens. Moreover, 32 drugs were included in the drug-gene network, with twelve drugs targeting STAT6, nine drugs targeting NFKBIA, four drugs targeted IKBKG, and seven drugs targeted FCGR2A. The expression of the four hub genes in blood samples determined by RT-qPCR was consistent with our analysis.

CONCLUSION

In conclusion, four hub genes (IKBKG, STAT6, NFKBIA, and FCGR2A) related to STING with a diagnostic value for DR were identified by bioinformatics analysis, which might provide new insights into the evaluation and treatment of DR.

Induced regulatory T cells as immunotherapy in allotransplantation and autoimmunity: challenges and opportunities

Regulatory T cells play a crucial role in the homeostasis of the immune response. Regulatory T cells are mainly generated in the thymus and are characterized by the expression of Foxp3, which is considered the regulatory T-cell master transcription factor. In addition, regulatory T cells can be induced from naive CD4+ T cells to express Foxp3 under specific conditions both in vivo (peripheral regulatory T cells) and in vitro (induced regulatory T cells). Both subsets of thymic regulatory T cells and peripheral regulatory T cells are necessary for the establishment of immune tolerance to self and non-self antigens. Although it has been postulated that induced regulatory T cells may be less stable compared to regulatory T cells, mainly due to epigenetic differences, accumulating evidence in animal models shows that induced regulatory T cells are stable in vivo and can be used for the treatment of inflammatory disorders, including autoimmune diseases and allogeneic transplant rejection. In this review, we describe the biological characteristics of induced regulatory T cells, as well as the key factors involved in induced regulatory T-cell transcriptional, metabolic, and epigenetic regulation, and discuss recent advances for de novo generation of stable regulatory T cells and their use as immunotherapeutic tools in different experimental models. Moreover, we discuss the challenges and considerations for the application of induced regulatory T cells in clinical trials and describe the new approaches proposed to achieve in vivo stability, including functional or metabolic reprogramming and epigenetic editing.

Changes in Circulating CD44+CD62L- Treg Subsets and CD44-CD62L+ Treg Subsets Reflect the Clinical Status of Patients with Allergic Rhinitis

INTRODUCTION

This study clarified the expression changes and clinical significance of CD44+CD62L- Treg and CD44-CD62L+ Treg subsets in the peripheral blood of patients with allergic rhinitis (AR).

METHODS

The peripheral blood of 39 patients with AR and 42 healthy controls was collected. Clinical data, such as sex, age, IgE titer, allergen screening information and visual analogue scale (VAS) score, were recorded. Changes in serum IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ were detected using the cytometric bead array method. Flow cytometry was used to detect the proportions of Th1, Th2, Th17, TFH, and Th9 cells and the proportions of CD44+CD62L- Treg and CD44-CD62L+ Treg subsets. Correlation analysis was performed between the CD44+CD62L- Treg subsets and the CD44-CD62L+ Treg subsets with clinical indicators (VAS score, total IgE titer), cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ), and Th1/Th2/Th17/TFH/Th9 cell proportions.

RESULTS

Compared to the control group, the proportion of total Treg cells and CD44+CD62L- Treg cells in the AR group decreased, and the proportion of CD44-CD62L+ Treg cells increased (p < 0.05). The proportions of CD44+CD62L- Treg cells significantly negatively correlated with Th2 cells (R = -0.5270, p < 0.05) and positively correlated with Treg cytokine IL-10 (R = 0.6447, p < 0.05). In addition, CD44+CD62L- Treg cells negatively correlated with the VAS score (R = -0.4956, p < 0.05), total IgE level (R = -0.4177, p < 0.05) and Th2 cytokine IL-6 level (R = -0.3034, p < 0.05) but positively correlated with the Th1 cytokine IL-2 (R = 0.4331, p < 0.05). In contrast, the proportion of CD44+CD62L- Treg cells significantly positively correlated with the Th2 cells (R = 0.6187, p < 0.05). Moreover, the proportion of CD44-CD62L+ Treg cells positively correlated with the VAS score (R = 0.4060, p < 0.05), total IgE level (R = 0.5224, p < 0.05) and Th2 cytokine IL-4 (R = 0.2647, p < 0.05) and IL-6 levels (R = 0.3824, p < 0.05) but negatively correlated with Th1 cytokine IL-2 (R = -0.3451, p < 0.05) and IL-10 (R = -0.3277, p < 0.05).

CONCLUSION

A greater proportion of CD44+CD62L- Tregs correlated with better reversal of the Th1/Th2 imbalance and milder clinical symptoms in AR patients. The presence of more CD44-CD62L+ Tregs correlated with a weaker immunosuppressive effect on Th2 cells and more severe clinical symptoms in AR patients. These findings provide new perspectives for the treatment and disease monitoring of AR.

Fasting alleviates bleomycin-induced lung inflammation and fibrosis via decreased Tregs and monocytes

PURPOSE

Idiopathic pulmonary fibrosis (IPF), a chronic and progressively worsening condition characterized by interstitial lung inflammation and fibrosis of unknown etiology, has a grim prognosis. The treatment options for IPF are limited and new therapeutic strategies are urgently needed. Dietary restriction can improve various inflammatory diseases, but its therapeutic effect on bleomycin (BLM)-induced pulmonary fibrosis mouse model remains unclear. This study aims to investigate whether intermittent fasting (IF) can alleviate BLM-induced pulmonary inflammation and fibrosis.

METHODS

Pulmonary fibrosis mouse models were induced by BLM. The IF group underwent 24-h fasting cycles for one week prior and three weeks following BLM administration. Meanwhile, the ad libitum feeding group had unrestricted access to food throughout the experiment. The evaluation focused on lung pathology via histological staining, qPCR analysis of collagen markers, and immune cell profiling through flow cytometry.

RESULTS

IF group significantly reduced inflammation and fibrosis in lung tissues of BLM-induced mice compared to ad libitum feeding group. qPCR results showed IF remarkably decreased the mRNA expression of Col 1a and Col 3a in the lungs of BLM-induced mouse models. IF also reduced the numbers of regulatory T cells (Tregs), T helper 17 (Th17) cells, monocytes, and monocyte-derived alveolar macrophages (MoAMs) in the lung tissues.

CONCLUSIONS

IF may improve BLM-induced pulmonary fibrosis by decreasing numbers of immune cells including Treg cells, Th17 ​cells, monocytes, and MoAMs in the lungs. This study offers experimental validation for dietary intervention as a viable treatment modality in IPF management.

Targeting CXCR4 impaired T regulatory function through PTEN in renal cancer patients

BACKGROUND

Tregs trafficking is controlled by CXCR4. In Renal Cell Carcinoma (RCC), the effect of the new CXCR4 antagonist, R54, was explored in peripheral blood (PB)-Tregs isolated from primary RCC patients.

METHODS

PB-Tregs were isolated from 77 RCC patients and 38 healthy donors (HDs). CFSE-T effector-Tregs suppression assay, IL-35, IFN-γ, IL-10, TGF-β1 secretion, and Nrp-1+Tregs frequency were evaluated. Tregs were characterised for CTLA-4, PD-1, CD40L, PTEN, CD25, TGF-β1, FOXP3, DNMT1 transcriptional profile. PTEN-pAKT signalling was evaluated in the presence of R54 and/or triciribine (TCB), an AKT inhibitor. Methylation of TSDR (Treg-Specific-Demethylated-Region) was conducted.

RESULTS

R54 impaired PB-RCC-Tregs function, reduced Nrp-1+Tregs frequency, the release of IL-35, IL-10, and TGF-β1, while increased IFN-γ Teff-secretion. The CXCR4 ligand, CXCL12, recruited CD25+PTEN+Tregs in RCC while R54 significantly reduced it. IL-2/PMA activates Tregs reducing pAKT+Tregs while R54 increases it. The AKT inhibitor, TCB, prevented the increase in pAKT+Tregs R54-mediated. Moreover, R54 significantly reduced FOXP3-TSDR demethylation with DNMT1 and FOXP3 downregulation.

CONCLUSION

R54 impairs Tregs function in primary RCC patients targeting PTEN/PI3K/AKT pathway, reducing TSDR demethylation and FOXP3 and DNMT1 expression. Thus, CXCR4 targeting is a strategy to inhibit Tregs activity in the RCC tumour microenvironment.

Induction of FoxP3 Pre-mRNA Alternative Splicing to Enhance the Suppressive Activity of Regulatory T Cells from Amyotrophic Lateral Sclerosis Patients

Forkhead box protein 3 (FoxP3) is a key transcription factor responsible for the development, maturation, and function of regulatory T cells (Tregs). The FoxP3 pre-mRNA is subject to alternative splicing, resulting in the translation of multiple splice variants. We have shown that Tregs from patients with amyotrophic lateral sclerosis (ALS) have reduced expression of full-length (FL) FoxP3, while other truncated splice variants are expressed predominantly. A correlation was observed between the reduced number of Tregs in the peripheral blood of ALS patients, reduced total FoxP3 mRNA, and reduced mRNA of its FL splice variant. Induction of FL FoxP3 was achieved using splice-switching oligonucleotides capable of base pairing with FoxP3 pre-mRNA and selectively modulating the inclusion of exons 2 and 7 in the mature mRNA. Selective expression of FL FoxP3 resulted in the induction of CD127low, CD152, and Helios-positive cells, while the cell markers CD4 and CD25 were not altered. Such Tregs had an increased proliferative activity and a higher frequency of cell divisions per day. The increased suppressive activity of Tregs with the induced FL FoxP3 splice variant was associated with the increased synthesis of the pro-apoptotic granzymes A and B, and perforin, IL-10, and IL-35, which are responsible for contact-independent suppression, and with the increased ability to suppress telomerase in target cells. The upregulation of Treg suppressive and proliferative activity using splice-switching oligonucleotides to induce the predominant expression of the FoxP3 FL variant is a promising approach for regenerative cell therapy in Treg-associated diseases.

The Role of Regulatory T Cells and Their Therapeutic Potential in Hypertensive Disease of Pregnancy: A Literature Review

Hypertensive disorders of pregnancy (HDP), including preeclampsia (PE) and gestational hypertension (GH), are major causes of maternal and foetal morbidity and mortality. This review elucidates the role of regulatory T cells (Tregs) in the immunological aspects of HDP and explores their therapeutic potential. Tregs, which play a critical role in maintaining immune homeostasis, are crucial in pregnancy to prevent immune-mediated rejection of the foetus. The review highlights that Tregs contribute to immunological adaptation in normal pregnancy, ensuring foetal acceptance. In contrast, HDP is associated with Treg dysfunction, which is marked by decreased numbers and impaired regulatory capacity, leading to inadequate immune tolerance and abnormal placental development. This dysfunction is particularly evident in PE, in which Tregs fail to adequately modulate the maternal immune response against foetal antigens, contributing to the pathophysiology of the disorder. Therapeutic interventions aiming to modulate Treg activity represent a promising avenue for HDP management. Studies in animal models and limited clinical trials suggest that enhancing Treg functionality could mitigate HDP symptoms and improve pregnancy outcomes. However, given the multifactorial nature of HDP and the intricate regulatory mechanisms of Tregs, the review explores the complexities of translating in vitro and animal model findings into effective clinical therapies. In conclusion, while the precise role of Tregs in HDP is still being unravelled, their central role in immune regulation during pregnancy is indisputable. Further research is needed to fully understand the mechanisms by which Tregs contribute to HDP and to develop targeted therapies that can safely and effectively harness their regulatory potential for treating hypertensive diseases of pregnancy.

Modulation of Suppressive Activity and Proliferation of Human Regulatory T Cells by Splice-Switching Oligonucleotides Targeting FoxP3 Pre-mRNA

The maturation, development, and function of regulatory T cells (Tregs) are under the control of the crucial transcription factor Forkhead Box Protein 3 (FoxP3). Through alternative splicing, the human FoxP3 gene produces four different splice variants: a full-length variant (FL) and truncated variants with deletions of each of exons 2 (∆2 variant) or 7 (∆7 variant) or a deletion of both exons (∆2∆7 variant). Their involvement in the biology of Tregs as well as their association with autoimmune diseases remains to be clarified. The aim of this work was to induce a single FoxP3 splice variant in human Tregs by splice switching oligonucleotides and to monitor their phenotype and proliferative and suppressive activity. We demonstrated that Tregs from peripheral blood from patients with multiple sclerosis preferentially expressed truncated splice variants, while the FL variant was the major variant in healthy donors. Tregs with induced expression of truncated FoxP3 splice variants demonstrated lower suppressive activity than those expressing FL variants. Reduced suppression was associated with the decreased expression of Treg-associated suppressive surface molecules and the production of cytokines. The deletion of exons 2 and/or 7 also reduced the cell proliferation rate. The results of this study show an association between FoxP3 splice variants and Treg function and proliferation. The modulation of Treg suppressive activity by the induction of the FoxP3 FL variant can become a promising strategy for regenerative immunotherapy.

Overview of the Gut-Brain Axis: From Gut to Brain and Back Again

The gut-brain axis refers to a bidirectional communication pathway linking the gastrointestinal system to the central nervous system. The hardware of this multifaceted pathway takes many forms, at once structural (neurons, microglia, intestinal epithelial cell barrier), chemical (neurotransmitters, enteroendocrine hormones, bacterial metabolites), and cellular (immune signaling, inflammatory pathways). The gut-brain axis is exquisitely influenced by our environment, diet, and behaviors. Here, we will describe recent progress in understanding the gut-brain axis in neurological disease, using Parkinson's disease as a guide. We will see that each component of the gut-brain axis is heavily mediated by intestinal microbiota and learn how gut-brain communication can go awry in microbial dysbiosis.

Effects of rIL2/anti-IL2 antibody complex on chikungunya virus-induced chronic arthritis in a mouse model

Chikungunya virus (CHIKV) is characterized by disabling joint pain that can cause persistent arthritis in approximately one-fourth of patients. Currently, no standard treatments are available for chronic CHIKV arthritis. Our preliminary data suggest that decreases in interleukin-2 (IL2) levels and regulatory T cell (Treg) function may play a role in CHIKV arthritis pathogenesis. Low-dose IL2-based therapies for autoimmune diseases have been shown to up-regulate Tregs, and complexing IL2 with anti-IL2 antibodies can prolong the half-life of IL2. A mouse model for post-CHIKV arthritis was used to test the effects of recombinant IL2 (rIL2), an anti-IL2 monoclonal antibody (mAb), and the complex on tarsal joint inflammation, peripheral IL2 levels, Tregs, CD4 + effector T cells (Teff), and histological disease scoring. The complex treatment resulted in the highest levels of IL2 and Tregs, but also increased Teffs, and therefore did not significantly reduce inflammation or disease scores. However, the antibody group, which had moderately increased levels of IL2 and activated Tregs, resulted in a decreased average disease score. These results suggest the rIL2/anti-IL2 complex stimulates both Tregs and Teffs in post-CHIKV arthritis, while the anti-IL2 mAb increases IL2 availability enough to shift the immune environment towards a tolerogenic one.

Regulatory T cells (Tregs) and their therapeutic potential against autoimmune disorders - Advances and challenges

Autoimmune diseases are caused when immune cells act against self-protein. This biological self-non-self-discrimination phenomenon is controlled by a distinct group of lymphocytes known as regulatory T cells (Tregs), which are key inflammatory response regulators and play a pivotal role in immune tolerance and homeostasis. Treg-mediated robust immunosuppression provides self-tolerance and protection against autoimmune diseases. However, once this system fails to operate or poorly operate, it leads to an extreme situation where immune system reacts against self-antigens and destroys host organs, thus causing autoimmune diseases. Tregs can target both innate and adaptive immunity via modulating multiple immune cells such as neutrophils, monocytes, antigen-presenting cells, B cells, and T cells. This review highlights the Treg-mediated immunosuppression, role of several markers and their interplay during Treg development and differentiation, and advances in therapeutic aspects of Treg cells to reduce severity of autoimmunity-related conditions along with emphasizing limitations and challenges of their usages.

Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.

Engineered nanomaterials trigger abscopal effect in immunotherapy of metastatic cancers

Despite advances in cancer treatment, metastatic cancer is still the main cause of death in cancer patients. At present, the treatment of metastatic cancer is limited to palliative care. The abscopal effect is a rare phenomenon in which shrinkage of metastatic tumors occurs simultaneously with the shrinkage of a tumor receiving localized treatment, such as local radiotherapy or immunotherapy. Immunotherapy shows promise for cancer treatment, but it also leads to consequences such as low responsiveness and immune-related adverse events. As a promising target-based approach, intravenous or intratumoral injection of nanomaterials provides new opportunities for improving cancer immunotherapy. Chemically modified nanomaterials may be able to trigger the abscopal effect by regulating immune cells. This review discusses the use of nanomaterials in killing metastatic tumor cells through the regulation of immune cells and the prospects of such nanomaterials for clinical use.

Nature vs. nurture: FOXP3, genetics, and tissue environment shape Treg function

The importance of regulatory T cells (Tregs) in preventing autoimmunity has been well established; however, the precise alterations in Treg function in autoimmune individuals and how underlying genetic associations impact the development and function of Tregs is still not well understood. Polygenetic susceptibly is a key driving factor in the development of autoimmunity, and many of the pathways implicated in genetic association studies point to a potential alteration or defect in regulatory T cell function. In this review transcriptomic control of Treg development and function is highlighted with a focus on how these pathways are altered during autoimmunity. In combination, observations from autoimmune mouse models and human patients now provide insights into epigenetic control of Treg function and stability. How tissue microenvironment influences Treg function, lineage stability, and functional plasticity is also explored. In conclusion, the current efficacy and future direction of Treg-based therapies for Type 1 Diabetes and other autoimmune diseases is discussed. In total, this review examines Treg function with focuses on genetic, epigenetic, and environmental mechanisms and how Treg functions are altered within the context of autoimmunity.

Ozone Pollution, Oxidative Stress, Regulatory T Cells and Antioxidants

Ozone pollution, is a serious health problem worldwide. Repeated exposure to low ozone doses causes a loss of regulation of the oxidation–reduction systems, and also induces a chronic state of oxidative stress. This fact is of special importance for the regulation of different systems including the immune system and the inflammatory response. In addition, the oxidation–reduction balance modulates the homeostasis of these and other complex systems such as metabolism, survival capacity, cell renewal, and brain repair, etc. Likewise, it has been widely demonstrated that in chronic degenerative diseases, an alteration in the oxide-reduction balance is present, and this alteration causes a chronic loss in the regulation of the immune response and the inflammatory process. This is because reactive oxygen species disrupt different signaling pathways. Such pathways are related to the role of regulatory T cells (Treg) in inflammation. This causes an increase in chronic deterioration in the degenerative disease over time. The objective of this review was to study the relationship between environmental ozone pollution, the chronic state of oxidative stress and its effect on Treg cells, which causes the loss of regulation in the inflammatory response as well as the role played by antioxidant systems in various pathologies.

Negative effects of brain regulatory T cells depletion on epilepsy

The infiltration of immune cells is observed in the epileptogenic zone; however, the relationship between epilepsy and regulatory T cells (Tregs) remains only partially understood. We aimed to investigate brain-infiltrating Tregs to reveal their underlying role in epilepsy. We analyzed the infiltration of Tregs in the epileptogenic zones from patients with epilepsy and a pilocarpine-induced temporal lobe epilepsy (TLE) model. Next, we evaluated the effects of brain Treg depletion on neuroinflammation, neuronal loss, oxidative stress, seizure activity and behavioral changes in the pilocarpine model. We also explored the impact of Treg expansion in the brain on seizure activity. There were a large number of Tregs in the epileptogenic zones of human and experimental epilepsy. The number of brain Tregs was negatively correlated with the frequency of seizures in patients with epilepsy. Our further findings demonstrated that brain Treg depletion promoted astrocytosis, microgliosis, inflammatory cytokine production, oxidative stress, and neuronal loss in the hippocampus after status epilepticus (SE). Moreover, brain Treg depletion increased seizure activity and contributed to behavioral impairments in experimental chronic TLE. Interestingly, intracerebroventricular injection of CCL20 amplified Tregs in brain tissue, thereby inhibiting seizure activity. Taken together, our study highlights the therapeutic potential of regulating Tregs in epileptic brain tissue.

Implications of regulatory T cells in non-lymphoid tissue physiology and pathophysiology

Treg cells have been initially described as gatekeepers for the control of autoimmunity, as they can actively suppress the activity of other immune cells. However, their role goes beyond this as Treg cells further control immune responses during infections and tumor development. Furthermore, Treg cells can acquire additional properties for e.g., the control of tissue homeostasis. This is instructed by a specific differentiation program and the acquisition of effector properties unique to Treg cells in non-lymphoid tissues. These tissue Treg cells can further adapt to their tissue environment and acquire distinct functional properties through specific transcription factors activated by a combination of tissue derived factors, including tissue-specific antigens and cytokines. In this review, we will focus on recent findings extending our current understanding of the role and differentiation of these tissue Treg cells. As such we will highlight the importance of tissue Treg cells for tissue maintenance, regeneration, and repair in adipose tissue, muscle, CNS, liver, kidney, reproductive organs, and the lung.

TREGking From Gut to Brain: The Control of Regulatory T Cells Along the Gut-Brain Axis

The human gastrointestinal tract has an enormous and diverse microbial community, termed microbiota, that is necessary for the development of the immune system and tissue homeostasis. In contrast, microbial dysbiosis is associated with various inflammatory and autoimmune diseases as well as neurological disorders in humans by affecting not only the immune system in the gastrointestinal tract but also other distal organs. FOXP3⁺ regulatory T cells (Tregs) are a subset of CD4⁺ helper T cell lineages that function as a gatekeeper for immune activation and are essential for peripheral autoimmunity prevention. Tregs are crucial to the maintenance of immunological homeostasis and tolerance at barrier regions. Tregs reside in both lymphoid and non-lymphoid tissues, and tissue-resident Tregs have unique tissue-specific phenotype and distinct function. The gut microbiota has an impact on Tregs development, accumulation, and function in periphery. Tregs, in turn, modulate antigen-specific responses aimed towards gut microbes, which supports the host–microbiota symbiotic interaction in the gut. Recent studies have indicated that Tregs interact with a variety of resident cells in central nervous system (CNS) to limit the progression of neurological illnesses such as ischemic stroke, Alzheimer’s disease, and Parkinson’s disease. The gastrointestinal tract and CNS are functionally connected, and current findings provide insights that Tregs function along the gut-brain axis by interacting with immune, epithelial, and neuronal cells. The purpose of this study is to explain our current knowledge of the biological role of tissue-resident Tregs, as well as the interaction along the gut-brain axis.

Zbtb20 identifies and controls a thymus-derived population of regulatory T cells that play a role in intestinal homeostasis

The expression of BTB-ZF transcription factors such as ThPOK in CD4⁺ T cells, Bcl6 in T follicular helper cells, and PLZF in natural killer T cells defines the fundamental nature and characteristics of these cells. Screening for lineage-defining BTB-ZF genes led to the discovery of a subset of T cells that expressed Zbtb20. About half of Zbtb20⁺ T cells expressed FoxP3, the lineage-defining transcription factor for regulatory T cells (T_regs). Zbtb20⁺ T_regs were phenotypically and genetically distinct from the larger conventional T_reg population. Zbtb20⁺ T_regs constitutively expressed mRNA for interleukin-10 and produced high levels of the cytokine upon primary activation. Zbtb20⁺ T_regs were enriched in the intestine and specifically expanded when inflammation was induced by the use of dextran sodium sulfate. Conditional deletion of Zbtb20 in T cells resulted in a loss of intestinal epithelial barrier integrity. Consequently, knockout (KO) mice were acutely sensitive to colitis and often died because of the disease. Adoptive transfer of Zbtb20⁺ T_regs protected the Zbtb20 conditional KO mice from severe colitis and death, whereas non-Zbtb20 T_regs did not. Zbtb20 was detected in CD24^hi double-positive and CD62L^lo CD4 single-positive thymocytes, suggesting that expression of the transcription factor and the phenotype of these cells were induced during thymic development. However, Zbtb20 expression was not induced in "conventional" T_regs by activation in vitro or in vivo. Thus, Zbtb20 expression identified and controlled the function of a distinct subset of T_regs that are involved in intestinal homeostasis.

Helminth infection modulates number and function of adipose tissue Tregs in high fat diet-induced obesity

Background

Epidemiological and experimental studies have shown a protective effect of helminth infections in weight gain and against the development of metabolic dysfunctions in the host. However, the mechanisms Treg cells exert in the helminth-obesity interface has been poorly investigated. The present study aimed to verify the influence of Heligmosomoides polygyrus infection in early stages of high fat diet-induced obesity.

Principal findings

The presence of infection was able to prevent exacerbated weight gain in mice fed with high fat diet when compared to non-infected controls. In addition, infected animals displayed improved insulin sensitivity and decreased fat accumulation in the liver. Obesity-associated inflammation was reduced in the presence of infection, demonstrated by lower levels of leptin and resistin, lower infiltration of Th1 and Th17 cells in adipose tissue, higher expression of IL10 and adiponectin, increased infiltration of Th2 and eosinophils in adipose tissue of infected animals. Of note, the parasite infection was associated with increased Treg frequency in adipose tissue which showed higher expression of cell surface markers of function and activation, like LAP and CD134. The infection could also increase adipose Treg suppressor function in animals on high fat diet.

Conclusion

These data suggest that H. polygyrus modulates adipose tissue Treg cells with implication for weight gain and metabolic syndrome.

Helminth infections are known to modulate the immune system being responsible for protecting the host from developing allergic and autoimmune disorders (Hygiene Hypothesis). We hypothesized that the same immunomodulatory effect could have an impact on immunometabolic diseases, such as obesity and its linked diseases such as type 2 diabetes. Weight disorders have reached epidemic levels, nearly tripling since 1975 and being responsible for almost 5 million premature deaths each year, but have been spared in areas of high helminth prevalence. To test our hypothesis C57BL/6 male mice were fed control or high fat diet, for five weeks, in the presence or not of infection with the worm Heligmosomoides polygyrus. Weight gain, development of metabolic disorders, inflammation and cellular migration to the adipose tissue were evaluated. In accordance with our hypothesis, we found that the presence of infection prevented the exacerbated weight gain and also improved metabolic parameters in animals fed a high fat diet. This was associated with the infection’s ability to modulate parameters of a cell responsible for regulatory functions: Tregs. In the light of these findings, helminth infection could be protective against weight gain and metabolic disturbances.

Multilevel mechanism of immune checkpoint inhibitor action in solid tumors: History, present issues and future development (Review)

Immunotherapy with checkpoint inhibitors (antibodies that target and block immune checkpoints in the tumor microenvironment) is included in the standard of care for patients with different types of malignancy, such as melanoma, renal cell and urothelial carcinoma, lung cancer etc. The introduction of this new immunotherapy has altered the view on potential targets for treatment of solid tumors from tumor cells themselves to their immune microenvironment; this has led to a reconsideration of the mechanisms of tumor-associated immunity. However, only a subset of patients benefit from immunotherapy and patient response is often unpredictable, even with known initial levels of prognostic markers; the biomarkers for favorable response are still being investigated. Mechanisms of immune checkpoint inhibitors efficiency, as well as the origins of treatment failure, require further investigation. From a clinical standpoint, discrepancies between the theoretical explanation of inhibitors of immune checkpoint actions at the cellular level and their deployment at a tissue/organ level impede the effective clinical implementation of novel immune therapy. The present review assessed existing experimental and clinical data on functional activity of inhibitors of immune checkpoints to provide a more comprehensive picture of their mechanisms of action on a cellular and higher levels of biological organization.

Tissue Resident Foxp3+ Regulatory T Cells: Sentinels and Saboteurs in Health and Disease

Foxp3⁺ regulatory T (Treg) cells are a CD4 T cell subset with unique immune regulatory function that are indispensable in immunity and tolerance. Their indisputable importance has been investigated in numerous disease settings and experimental models. Despite the extensive efforts in determining the cellular and molecular mechanisms operating their functions, our understanding their biology especially in vivo remains limited. There is emerging evidence that Treg cells resident in the non-lymphoid tissues play a central role in regulating tissue homeostasis, inflammation, and repair. Furthermore, tissue-specific properties of those Treg cells that allow them to express tissue specific functions have been explored. In this review, we will discuss the potential mechanisms and key cellular/molecular factors responsible for the homeostasis and functions of tissue resident Treg cells under steady-state and inflammatory conditions.

Network Pharmacology and Molecular Docking Analysis on Molecular Mechanism of Qingzi Zhitong Decoction in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a disease with complex pathological mechanisms. We explored the potential molecular mechanisms behind the therapeutic functions of Qingzi Zhitong decoction (QZZTD) in the treatment of UC by network pharmacology and molecular docking. QZZTD is a formula of Chinese traditional medicine consisting of 10 herbs. The potential active ingredients of QZZTD and their target genes were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform database, and UC-related target genes were obtained from GeneCards and OMIM databases. A total of 138 co-identified target genes were obtained by plotting the intersection target Venn diagram, and then the STRING database and Cytoscape software were used to establish protein-protein interaction networks and herb-ingredient-target networks. Four key active compounds and nine key proteins were identified. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that the biological functions of potential target genes were associated with DNA transcription, signaling receptor and ligand activity, cytokine activity, cellular autophagy, and antioxidant pathways, with related pathways involving the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway, advanced glycosylation end product (AGE)-RAGE signaling pathway, tumor necrosis factor (TNF) signaling pathway, and IL-17 signaling pathway. Moreover, the binding activities of key target genes and essential active compounds of Chinese herbal medicines in QZZTD were further validated by molecular docking. This demonstrated that quercetin, luteolin, hyndarin, and beta-sitosterol had good binding to eight key proteins, and Akt1 was the target protein with the best binding activity, suggesting that Akt1 could be the essential mediator responsible for signaling transduction after QZZTD administration. The rat experiment verified that QZZTD inhibited PI3K-Akt pathway activation and reduced inflammation in UC. In conclusion, our study suggested four potential key active components, including quercetin, were identified in QZZTD, which could interact with Akt1 and modulate the activation of the PI3K-Akt pathway. The other three pathways may also be involved in the signaling transduction induced by QZZTD in the treatment of UC.

Hyperoside Suppresses Renal Inflammation by Regulating Macrophage Polarization in Mice With Type 2 Diabetes Mellitus

Accumulating evidence reveals that both inflammation and lymphocyte dysfunction play a vital role in the development of diabetic nephropathy (DN). Hyperoside (HPS) or quercetin-3-O-galactoside is an active flavonoid glycoside mainly found in the Chinese herbal medicine Tu-Si-Zi. Although HPS has a variety of pharmacological effects, including anti-oxidative and anti-apoptotic activities as well as podocyte-protective effects, its underlying anti-inflammatory mechanisms remain unclear. Herein, we investigated the therapeutic effects of HPS on murine DN and the potential mechanisms responsible for its efficacy. We used C57BLKS/6J ^Lepdb/db mice and a high glucose (HG)-induced bone marrow-derived macrophage (BMDM) polarization system to investigate the potentially protective effects of HPS on DN. Our results showed that HPS markedly reduced diabetes-induced albuminuria and glomerular mesangial matrix expansion, accompanied with a significant improvement of fasting blood glucose level, hyperlipidaemia and body weight. Mechanistically, pretreatment with HPS effectively regulated macrophage polarization by shifting proinflammatory M1 macrophages (F4/80⁺CD11b⁺CD86⁺) to anti-inflammatory M2 ones (F4/80⁺CD11b⁺CD206⁺) in vivo and in bone marrow-derived macrophages (BMDMs) in vitro, resulting in the inhibition of renal proinflammatory macrophage infiltration and the reduction in expression of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor (TNF-α) and inducible nitric oxide synthase (iNOS) while increasing expression of anti-inflammatory cytokine Arg-1 and CD163/CD206 surface molecules. Unexpectedly, pretreatment with HPS suppressed CD4⁺ T cell proliferation in a coculture model of IL-4-induced M2 macrophages and splenic CD4⁺ T cells while promoting their differentiation into CD4⁺IL-4⁺ Th2 and CD4⁺Foxp3⁺ Treg cells. Taken together, we demonstrate that HPS ameliorates murine DN via promoting macrophage polarization from an M1 to M2 phenotype and CD4⁺ T cell differentiation into Th2 and Treg populations. Our findings may be implicated for the treatment of DN in clinic.

Airway Basal Cells, Protectors of Epithelial Walls in Health and Respiratory Diseases

The airway epithelium provides a critical barrier to the outside environment. When its integrity is impaired, epithelial cells and residing immune cells collaborate to exclude pathogens and to heal tissue damage. Healing is achieved through tissue-specific stem cells: the airway basal cells. Positioned near the basal membrane, airway basal cells sense and respond to changes in tissue health by initiating a pro-inflammatory response and tissue repair via complex crosstalks with nearby fibroblasts and specialized immune cells. In addition, basal cells have the capacity to learn from previous encounters with the environment. Inflammation can indeed imprint a certain memory on basal cells by epigenetic changes so that sensitized tissues may respond differently to future assaults and the epithelium becomes better equipped to respond faster and more robustly to barrier defects. This memory can, however, be lost in diseased states. In this review, we discuss airway basal cells in respiratory diseases, the communication network between airway basal cells and tissue-resident and/or recruited immune cells, and how basal cell adaptation to environmental triggers occurs.

Clinical Value and Potential Mechanisms of Oxysterol-Binding Protein Like 3 (OSBPL3) in Human Tumors

Cancer remains one of the top culprits causing disease-related deaths. A lack of effective multi-cancer therapeutic targets has limited the prolongation of cancer patients’ survival. Therefore, it is important to explore novel oncogenic genes or versatile targets and perform a comprehensive analysis to assess their roles in the process of tumorigenesis. OSBPL3 protein is an intracellular lipid receptor of the oxysterol-binding protein superfamily, which participates in some pathological and physiological processes in tumor progression. However, its clinical roles and potential mechanisms in cancers remain unknown. Thus, we aimed to systematic explore the potential oncogenic roles of OSBPL3 across thirty-three tumors using multiple web-based and publicly available tools, including the Cancer Genome Atlas, Gene Expression Omnibus, Genotype-Tissue Expression, cBioPortal, and Human Protein Atlas database. OSBPL3 is highly expressed in major subtypes of cancers, distinctly associated with the prognosis of tumor patients. We observed X676_splice/V676G alteration in the oxysterol domain and frequent mutations of OSBPL3 involve cell survival in skin cutaneous melanoma. We also first presented that the expression of OSBPL3 was associated with tumor mutational burden (TMB) in nine cancer types. Additionally, OSBPL3 shows an enhanced phosphorylation level at S426, S251, and S273 loci within the pleckstrin homology domain in multiple tumors, such as breast cancer or lung adenocarcinoma. And OSBPL3 expression was associated with active immune cells (CD8⁺ T cells) and cancer-associated fibroblasts in breast cancer, colon adenocarcinoma, and kidney renal clear cell carcinoma and immune checkpoint genes in more than 30 tumors, but weakly associated with immune suppressive cells (myeloid-derived suppressor cells, T regulatory cells). Moreover, protein processing and mRNA metabolic signaling pathways were involved in the functional mechanisms of OSBPL3. Our study first demonstrated that a novel agent OSBPL3 plays an important role in tumorigenesis from the perspective of publicly available databases and clinical tumor samples in various cancers, which comprehensively provide insights into its biological functions and may be helpful for further investigation.

Regulatory T cells promote innate inflammation after skin barrier breach via TGF-β activation

Regulatory T cells (T_regs) use multiple mechanisms to attenuate inflammation and prevent autoimmunity. T_regs residing in peripheral (i.e., nonlymphoid) tissues have specialized functions; specifically, skin T_regs promote wound healing, suppress dermal fibrosis, facilitate epidermal regeneration, and augment hair follicle cycling. Here, we demonstrated that skin T_regs were transcriptionally attuned to interact with their tissue environment through increased expression of integrin and TGF-β pathway genes that influence epithelial cell biology. We identified a molecular pathway where skin T_regs license keratinocytes to promote innate inflammation after skin barrier breach. Using a single-cell discovery approach, we identified preferential expression of the integrin αvβ8 on skin T_regs Upon skin injury, T_regs used this integrin to activate latent TGF-β, which acted directly on epithelial cells to promote CXCL5 production and neutrophil recruitment. Induction of this circuit delayed epidermal regeneration but provided protection from Staphylococcus aureus infection across a compromised barrier. Thus, αvβ8-expressing T_regs in the skin, somewhat paradoxical to their canonical immunosuppressive functions, facilitated inflammation acutely after loss of barrier integrity to promote host defense against infection.

Adiponectin-expressing Treg facilitate T lymphocyte development in thymic nurse cell complexes

Adiponectin is a well-known insulin sensitizer and anti-inflammatory molecule, possessing therapeutic potentials in cardiovascular, metabolic and cancer diseases. Results of the present study demonstrate that adiponectin is expressed in a population of regulatory T-cells (Treg) resided within the thymic nurse cell (TNC) complexes. Adoptive transfer of adiponectin-expressing Treg precursors effectively attenuated obesity, improved glucose and insulin tolerance, prevented fatty liver injuries in wild-type mice fed a high-fat diet, and significantly inhibited breast cancer development in MMTV-PyVT transgenic mice. Within the TNC complexes, locally produced adiponectin bound to and regulated the expression as well as the distribution of CD100, a transmembrane lymphocyte semaphorin, in turn modulating the lymphoepithelial interactions to facilitate T-cell development and maturation. In summary, adiponectin plays an important role in the selection and development of T lymphocytes within the TNC complexes. Adiponectin-expressing Treg represent a promising candidate for adoptive cell immunotherapy against obesity-related metabolic and cancer diseases.

The Complex Role of Regulatory T Cells in Immunity and Aging

The immune system is a tightly regulated network which allows the development of defense mechanisms against foreign antigens and tolerance toward self-antigens. Regulatory T cells (Treg) contribute to immune homeostasis by maintaining unresponsiveness to self-antigens and suppressing exaggerated immune responses. Dysregulation of any of these processes can lead to serious consequences. Classically, Treg cell functions have been described in CD4⁺ T cells, but other immune cells also harbour the capacity to modulate immune responses. Regulatory functions have been described for different CD8⁺ T cell subsets, as well as other T cells such as γδT cells or NKT cells. In this review we describe the diverse populations of Treg cells and their role in different scenarios. Special attention is paid to the aging process, which is characterized by an altered composition of immune cells. Treg cells can contribute to the development of various age-related diseases but they are poorly characterized in aged individuals. The huge diversity of cells that display immune modulatory functions and the lack of universal markers to identify Treg make the expanding field of Treg research complex and challenging. There are still many open questions that need to be answered to solve the enigma of regulatory T cells.

B and T Cell Immunity in Tissues and Across the Ages

B and T cells are key components of the adaptive immune system and coordinate multiple facets of immunity including responses to infection, vaccines, allergens, and the environment. In humans, B- and T-cell immunity has been determined using primarily peripheral blood specimens. Conversely, human tissues have scarcely been studied but they host multiple adaptive immune cells capable of mounting immune responses to pathogens and participate in tissue homeostasis. Mucosal tissues, such as the intestines and respiratory track, are constantly bombarded by foreign antigens and contain tissue-resident memory T (T_RM) cells that exhibit superior protective capacity to pathogens. Also, tissue-resident memory B (B_RM) cells have been identified in mice but whether humans have a similar population remains to be confirmed. Moreover, the immune system evolves throughout the lifespan of humans and undergoes multiple changes in its immunobiology. Recent studies have shown that age-related changes in tissues are not necessarily reflected in peripheral blood specimens, highlighting the importance of tissue localization and subset delineation as essential determinants of functional B and T cells at different life stages. This review describes our current knowledge of the main B- and T-cell subsets in peripheral blood and tissues across age groups.

Medawar and the immunological paradox of pregnancy: in context

In 1953, Peter Medawar defined 'the immunological paradox of pregnancy', whereby the semi-allogeneic foetus can survive for 9 months in its mother, while a semi-allogeneic graft would be rejected. Here, I revisit the immunological paradox of pregnancy, setting it in the context of the time in which it was proposed. I go on to examine the extent to which Medawar's ideas on the subject have stood the test of time and how they have shaped reproductive immunology.

The Role of Inflammation in Diabetic Retinopathy

Inflammation is central to pathogenic processes in diabetes mellitus and the metabolic syndrome and particularly implicates innate immunity in the development of complications. Inflammation is a primary event in Type 1 diabetes where infectious (viral) and/or autoimmune processes initiate disease; in contrast, chronic inflammation is typical in Type 2 diabetes and is considered a sequel to increasing insulin resistance and disturbed glucose metabolism. Diabetic retinopathy (DR) is perceived as a vascular and neurodegenerative disease which occurs after some years of poorly controlled diabetes. However, many of the clinical features of DR are late events and reflect the nature of the retinal architecture and its cellular composition. Retinal microvascular disease is, in fact, an early event pathogenetically, induced by low grade, persistent leukocyte activation which causes repeated episodes of capillary occlusion and, progressive, attritional retinal ischemia. The later, overt clinical signs of DR are a consequence of the retinal ischemia. Metabolic dysregulation involving both lipid and glucose metabolism may lead to leukocyte activation. On a molecular level, we have shown that macrophage-restricted protein tyrosine phosphatase 1B (PTP1B) is a key regulator of inflammation in the metabolic syndrome involving insulin resistance and it is possible that PTP1B dysregulation may underlie retinal microvascular disease. We have also shown that adherent CCR5⁺CD11b⁺ monocyte macrophages appear to be selectively involved in retinal microvascular occlusion. In this review, we discuss the relationship between early leukocyte activation and the later features of DR, common pathogenetic processes between diabetic microvascular disease and other vascular retinopathies, the mechanisms whereby leukocyte activation is induced in hyperglycemia and dyslipidemia, the signaling mechanisms involved in diabetic microvascular disease, and possible interventions which may prevent these retinopathies. We also address a possible role for adaptive immunity in DR. Although significant improvements in treatment of DR have been made with intravitreal anti-VEGF therapy, a sizeable proportion of patients, particularly with sight-threatening macular edema, fail to respond. Alternative therapies targeting inflammatory processes may offer an advantage.

Blunted Expansion of Regulatory T Lymphocytes Is Associated With Increased Bacterial Translocation in Patients With Major Depressive Disorder

Background: Major Depressive Disorder (MDD) is associated with both proinflammatory and adaptive immune response abnormalities. Regulatory T lymphocytes (Tregs), a subtype of CD4+ T cells, are relevant for maintaining immune-inflammatory system homeostasis and control of inflammation such as the kind potentially induced by the interactions between the intestinal microbiome and gut mucosa. We investigated the Treg population and its distribution along their stages of differentiation/activation, as well as its function in MDD patients without concomitant diseases. We also studied the potential association between Treg alterations, intestinal barrier damage, and bacterial translocation. Methods: 30 MDD patients and 20 healthy controls were studied. The levels of circulating CD25FoxP3⁺ Tregs and their distribution on the naïve (T_N), effector (T_E), central (T_CM), and effector memory(T_EM) differentiation/activation stages were analyzed using polychromatic flow cytometry. Chemokine receptors (CCR) 2, 5, and 6, and the intracytoplasmic IL-10 expression by the Tregs were also analyzed. The serum IL-10 was measured using Luminex. The serum levels of zonulin and the intestinal fatty acid-binding protein (I-FABP), both markers of gut barrier function, and the LPS-binding protein (LBP), a marker of bacterial translocation, were measured using an enzyme-linked immunosorbent assay. Results: MDD patients had increased number of circulating Tregs cells with enhanced number of Tregs at the T_N, T_E, T_CM, and T_EM stages. The percentage of Tregs cells at T_N stage was significantly higher in MDD patients. The percentage of Tregs that expressed CCR2 and CCR6 was increased as well as those expressing IL-10. MDD patients had significantly increased levels of circulating I-FABP and LBP. MDD patients with high LBP levels had a significant reduction in the number of circulating Tregs compared to normal-LBP MDD patients. Conclusions: MDD patients showed an expansion of circulating Tregs and their CD25^highFoxP3⁺ and CD25^lowFoxP3⁺ subsets throughout the different stages of CD4+ T lymphocyte differentiation/activation. Tregs also showed an increased frequency of cells expressing CCR6 and CCR2. IL-10 Treg production was also enhanced in MDD patients that concurrently had increased serum IL-10 levels. However, this Treg expansion was blunted in MDD patients with gut barrier damage and increased bacterial translocation.