Regulatory T-cell homeostasis: steady-state maintenance and modulation during inflammation

Vps34 sustains Treg cell survival and function via regulating intracellular redox homeostasis

The survival and suppressive function of regulatory T (Treg) cells rely on various intracellular metabolic and physiological processes. Our study demonstrates that Vps34 plays a critical role in maintaining Treg cell homeostasis and function by regulating cellular metabolic activities. Disruption of Vps34 in Treg cells leads to spontaneous fatal systemic autoimmune disorder and multi-tissue inflammatory damage, accompanied by a reduction in the number of Treg cells, particularly eTreg cells with highly immunosuppressive activity. Mechanistically, the poor survival of Vps34-deficient Treg cells is attributed to impaired endocytosis, intracellular vesicular trafficking and autophagosome formation, which further results in enhanced mitochondrial respiration and excessive ROS production. Removal of excessive ROS can effectively rescue the death of Vps34-deficient Treg cells. Functionally, acute deletion of Vps34 within established Treg cells enhances anti-tumor immunity in a malignant melanoma model by boosting T-cell-mediated anti-tumor activity. Overall, our results underscore the pivotal role played by Vps34 in orchestrating Treg cell homeostasis and function towards establishing immune homeostasis and tolerance.

Mitochondrial Oxidative Stress Regulates FOXP3+ T-Cell Activity and CD4-Mediated Inflammation in Older Adults with Frailty

In healthy older adults, the immune system generally preserves its response and contributes to a long, healthy lifespan. However, rapid deterioration in immune regulation can lead to chronic inflammation, termed inflammaging, which accelerates pathological aging and diminishes the quality of life in older adults with frailty. A significant limitation in current aging research is the predominant focus on comparisons between young and older populations, often overlooking the differences between healthy older adults and those experiencing pathological aging. Our study elucidates the intricate immunological dynamics of the CD4/Treg axis in frail older adults compared to comparable age-matched healthy older adults. By utilizing publicly available RNA sequencing and single-cell RNA sequencing (scRNAseq) data from peripheral blood mononuclear cells (PBMCs), we identified a specific Treg cell subset and transcriptional landscape contributing to the dysregulation of CD4+ T-cell responses. We explored the molecular mechanisms underpinning Treg dysfunction, revealing that Tregs from frail older adults exhibit reduced mitochondrial protein levels, impairing mitochondrial oxidative phosphorylation. This impairment is driven by the TNF/NF-kappa B pathway, leading to cumulative inflammation. Further, we gained a deeper understanding of the CD4/Treg axis by predicting the effects of gene perturbations on cellular signaling networks. Collectively, these findings highlight the age-related relationship between mitochondrial dysfunction in the CD4/Treg axis and its role in accelerating aging and frailty in older adults. Targeting Treg dysfunction offers a critical basis for developing tailored therapeutic strategies aimed at improving the quality of life in older adults.

The microbiome shapes immunity in a sex-specific manner in mouse models of Alzheimer's disease

INTRODUCTION

Preclinical studies reveal that the microbiome broadly affects immune responses and the deposition and/or clearance of amyloid-beta (Aβ) in mouse models of Alzheimer's disease (AD). Whether the microbiome shapes central and peripheral immune profiles in AD models remains unknown.

METHODS

We examined adaptive immune responses in two mouse models containing AD-related genetic predispositions (3xTg and 5xFAD) in the presence or absence of the microbiome.

RESULTS

T and B cells were altered in brain-associated and systemic immune tissues between genetic models and wildtype mice, with earlier signs if inflammation in female mice. Systemic immune responses were modulated by the microbiome and differed by sex. Further, the absence of a microbiome in germ-free mice resulted in reduced cognitive deficits, primarily in female mice.

DISCUSSION

These data reveal sexual dimorphism in early signs of inflammation and the effects of the microbiome, and highlight a previously unrecognized interaction between sex and the microbiome in mouse models of AD.

Research in Context

Systemic review: We reviewed the literature related to Alzheimer's disease (AD), inflammation, and the microbiome using PubMed. We cite several studies that demonstrate the influence of the microbiome on inflammation and cognitive performance in both animal models and humans. However, the mechanisms linking immunity to AD are not well understood. Interpretation: Using two well-established mouse models of AD, we found that the microbiome does not strongly influence the onset of inflammation in brain-draining lymph nodes; rather, it largely modulates systemic immune responses, local cytokine production, and cognitive performance. Notably, the inflammatory state in mice was affected by sex, and this sex effect differed between local and systemic tissues and mice with or without a microbiome. Future directions: Our work identified a sex- and microbiome-mediated effect on inflammation and cognitive performance. Future studies may focus on microbiome-dependent mechanisms that intersect with sex hormone and immune responses to determine peripheral effects on AD outcomes.

Highlights

Adaptive immunity is activated at early ages and differentially by sex in mouse models of AD.Inflammation in 5xFAD mice is characterized by increased IL-17A-producing T cells.Inflammation in 3xTg mice is characterized by increased cytokine responses in males, but attenuated cytokine responses in female mice.Longitudinal immune responses differ between 3xTg mice and 5xFAD mice.Both 3xTg and 5xFAD female mice show improved learning and cognition in the absence of a microbiome.

The double life of a chemotherapy drug: Immunomodulatory functions of gemcitabine in cancer

Although the development of immunotherapies has been revolutionary in the treatment of several cancers, many cancer types remain unresponsive to immune-based treatment and are largely managed by chemotherapy drugs. However, chemotherapeutics are not infallible and are frequently rendered ineffective as resistance develops from prolonged exposure. Recent investigations have indicated that some chemotherapy drugs have additional functions beyond their normative cytotoxic capacity and are in fact immune-modifying agents. Of the pharmaceuticals with identified immune-editing properties, gemcitabine is well-studied and of interest to clinicians and scientists alike. Gemcitabine is a chemotherapy drug approved for the treatment of multiple cancers, including breast, lung, pancreatic, and ovarian. Because of its broad applications, relatively low toxicity profile, and history as a favorable combinatory partner, there is promise in the recharacterization of gemcitabine in the context of the immune system. Such efforts may allow the identification of suitable immunotherapeutic combinations, wherein gemcitabine can be used as a priming agent to improve immunotherapy efficacy in traditionally insensitive cancers. This review looks to highlight documented immunomodulatory abilities of one of the most well-known chemotherapy agents, gemcitabine, relating to its influence on cells and proteins of the immune system.

Beyond Immune Balance: The Pivotal Role of Decidual Regulatory T Cells in Unexplained Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) is defined as two or more consecutive pregnancy failures, which brings tremendous stress to women of childbearing age and seriously affects family well-being. However, the reason in about 50% of cases remains unknown and is defined as unexplained recurrent spontaneous abortion (URSA). The immunological perspective in URSA has attracted widespread attention in recent years. The embryo is regarded as a semi-allogeneic graft to the mother. A successful pregnancy requires transition to an immune environment conducive to embryo survival at the maternal-fetal interface. As an important member of regulatory immunity, regulatory T (Treg) cells play a key role in regulating immune tolerance at the maternal-fetal interface. This review will focus on the phenotypic plasticity and lineage stability of Treg cells to illustrate its relationship with URSA.

Dysfunctional regulatory T cell: May be an obstacle to immunotherapy in cardiovascular diseases

Inflammatory responses are linked to cardiovascular diseases (CVDs) in various forms. Tregs, members of CD4+ T cells, play important roles in regulating immune system and suppressing inflammatory response, thus contributing to maintaining immune homeostasis. However, Tregs exert their powerful suppressive function relying on the stable phenotype and function. The stability of Tregs primarily depends on the FOXP3 (Forkhead box P3) expression and epigenetic regulation. Although Tregs are quite stable under physiological conditions, prolonged exposure to inflammatory cues, Tregs may lose suppressive function and require proinflammatory phenotype, namely plastic Tregs or ex-Tregs. There are extensive researches have established the beneficial role of Tregs in CVDs. Nevertheless, the potential risks of dysfunctional Tregs lack deep research. Anti-inflammatory and immunological modulation have been hotspots in the treatment of CVDs. Tregs are appealing because of their crucial role in resolving inflammation and promoting tissue repair. If alleviating inflammatory response through modulating Tregs could be a new therapeutic strategy for CVDs, the next step to consider is how to prevent the formation of dysfunctional Tregs or reverse detrimental Tregs to normal phenotype.

Regulatory T cells use heparanase to access IL-2 bound to extracellular matrix in inflamed tissue

Although FOXP3+ regulatory T cells (Treg) depend on IL-2 produced by other cells for their survival and function, the levels of IL-2 in inflamed tissue are low, making it unclear how Treg access this critical resource. Here, we show that Treg use heparanase (HPSE) to access IL-2 sequestered by heparan sulfate (HS) within the extracellular matrix (ECM) of inflamed central nervous system tissue. HPSE expression distinguishes human and murine Treg from conventional T cells and is regulated by the availability of IL-2. HPSE-/- Treg have impaired stability and function in vivo, including in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis. Conversely, endowing monoclonal antibody-directed chimeric antigen receptor (mAbCAR) Treg with HPSE enhances their ability to access HS-sequestered IL-2 and their ability to suppress neuroinflammation in vivo. Together, these data identify a role for HPSE and the ECM in immune tolerance, providing new avenues for improving Treg-based therapy of autoimmunity.

Regulatory T lymphocytes in traumatic brain injury

Traumatic brain injury (TBI) presents a significant global health challenge with no effective therapies developed to date. Regulatory T lymphocytes (Tregs) have recently emerged as a potential therapy due to their critical roles in maintaining immune homeostasis, reducing inflammation, and promoting brain repair. Following TBI, fluctuations in Treg populations and shifts in their functionality have been noted. However, the precise impact of Tregs on the pathophysiology of TBI remains unclear. In this review, we discuss recent advances in understanding the intricate roles of Tregs in TBI and other brain diseases. Increased knowledge about Tregs may facilitate their future application as an immunotherapy target for TBI treatment.

Immunogenicity and efficacy of an oral live-attenuated vaccine for bovine Johne's disease

Mycobacterium avium subsp. paratuberculosis (MAP), the etiological agent of Johne's disease (JD) in ruminants, establishes a prolonged and often lifelong enteric infection. The implementation of control measures for bovine JD has faced obstacles due to the considerable expenses involved in disease surveillance and hindered by unreliable and inadequate diagnostic tests, emphasizing the need for an effective vaccine that can stimulate mucosal immunity in the gastrointestinal tract. Previous investigations have demonstrated that deletion of the BacA gene in MAP produces an attenuated strain that can transiently colonize the calf small intestine while retaining its capacity to stimulate systemic immune responses similar to wildtype MAP strains. This study assessed the efficacy of the BacA gene deletion MAP strain, referred to as the BacA vaccine, when administered orally to young calves. The research aimed to evaluate its effectiveness in controlling MAP intestinal infection and to investigate the immune responses elicited by mucosal vaccination. The study represents the first evaluation of an enteric modified live MAP vaccine in the context of an oral MAP challenge in young calves. Oral immunization with BacA reduced MAP colonization specifically in the ileum and ileocecal valve. This partially protective immune response was associated with an increased frequency of CD4+ and CD8+ T cells with a pro-inflammatory phenotype (IFNγ+/TNFα+) in vaccinated animals. Moreover, re-stimulated PBMCs from vaccinated animals showed increased expression of IFNγ, IP-10, IL-2, and IL-17 at 10- and 12-weeks post challenge. Furthermore, immunophenotyping of blood leukocytes revealed that vaccinated calves had increased levels of T cells expressing cell-surface markers consistent with long-term central memory. Overall, our findings provide new insights into the development and immunogenicity of a modified live MAP vaccine against bovine JD, demonstrating oral vaccination can stimulate host immune responses that can be protective against enteric MAP infection.

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.

RIPK1 plays a crucial role in maintaining regulatory T-Cell homeostasis by inhibiting both RIPK3- and FADD-mediated cell death

Regulatory T (Treg) cells play an essential role in maintaining immune balance across various physiological and pathological conditions. However, the mechanisms underlying Treg homeostasis remain incompletely understood. Here, we report that RIPK1 is crucial for Treg cell survival and homeostasis. We generated mice with Treg cell-specific ablation of Ripk1 and found that these mice developed fatal systemic autoimmunity due to a dramatic reduction in the Treg cell compartment caused by excessive cell death. Unlike conventional T cells, Treg cells with Ripk1 deficiency were only partially rescued from cell death by blocking FADD-dependent apoptosis. However, simultaneous removal of both Fadd and Ripk3 completely restored the homeostasis of Ripk1-deficient Treg cells by blocking two cell death pathways. Thus, our study highlights the critical role of RIPK1 in regulating Treg cell homeostasis by controlling both apoptosis and necroptosis, thereby providing novel insights into the mechanisms of Treg cell homeostasis.

T Cell Subsets and Immune Homeostasis

T cells are a heterogeneous group of cells that can be classified into different subtypes according to different classification methods. The body's immune system has a highly complex and effective regulatory network that allows for the relative stability of immune system function. Maintaining proper T cell homeostasis is essential for promoting protective immunity and limiting autoimmunity and tumor formation. Among the T cell family members, more and more T cell subsets have gradually been characterized. In this chapter, we summarize the functions of some key T cell subsets and their impact on immune homeostasis.

Th2 Cell Activation in Chronic Liver Disease Is Driven by Local IL33 and Contributes to IL13-Dependent Fibrogenesis

BACKGROUND & AIMS

Type 2 immune responses contribute to liver fibrosis in parasite infections, but their role in other liver diseases is less well understood. Here, we aimed at unravelling mechanisms involved in T helper 2 (Th2) T-cell polarization, activation, and recruitment in human liver fibrosis and cirrhosis.

METHODS

Tissues, cells, and serum from human livers were analyzed using quantitative reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, fluorescence in situ hybridization, immunostaining, flow cytometry, and various functional in vitro assays. Cellular interactions and soluble mediators involved in T-cell polarization and recruitment were studied, as well as their effect on hepatic stellate cell (HSC) activation, proliferation, and extracellular matrix synthesis.

RESULTS

In human liver fibrosis, a stage-dependent increase in Th2-related transcription factors, Th2 cytokines, and trans-acting T-cell-specific transcription factor-expressing T cells was observed, and was highest in cirrhotic livers. The alarmin interleukin (IL)33 was found to be increased in livers and sera from patients with cirrhosis, to act as a chemotactic agent for Th2 cells, and to induce type 2 polarization of CD4+ T cells. Oval cells, liver sinusoidal endothelial cells, intrahepatic macrophages, and migrating monocytes were identified as sources of IL33. IL33-activated T cells, but not IL33 alone, induced HSC activation, as shown by Ki67 and α-smooth muscle actin staining, increased collagen type I alpha 1 chain messenger RNA expression, and wound healing assays. The profibrotic effect of IL33-activated T cells was contact-independent and could be antagonized using monoclonal antibodies against IL13.

CONCLUSION

In patients with chronic liver disease, the alarmin IL33 promotes the recruitment and activation of CD4+ T cells with Th2-like properties, which activate paracrine HSC in an IL13-dependent manner and promotes fibrogenesis.

Aged intestinal stem cells propagate cell-intrinsic sources of inflammaging in mice

Low-grade chronic inflammation is a hallmark of ageing, associated with impaired tissue function and disease development. However, how cell-intrinsic and -extrinsic factors collectively establish this phenotype, termed inflammaging, remains poorly understood. We addressed this question in the mouse intestinal epithelium, using mouse organoid cultures to dissect stem cell-intrinsic and -extrinsic sources of inflammaging. At the single-cell level, we found that inflammaging is established differently along the crypt-villus axis, with aged intestinal stem cells (ISCs) strongly upregulating major histocompatibility complex class II (MHC-II) genes. Importantly, the inflammaging phenotype was stably propagated by aged ISCs in organoid cultures and associated with increased chromatin accessibility at inflammation-associated loci in vivo and ex vivo, indicating cell-intrinsic inflammatory memory. Mechanistically, we show that the expression of inflammatory genes is dependent on STAT1 signaling. Together, our data identify that intestinal inflammaging in mice is promoted by a cell-intrinsic mechanism, stably propagated by ISCs, and associated with a disbalance in immune homeostasis.

Transcriptome profiling of regulatory T cells from children with transient hypogammaglobulinemia of infancy

Transient hypogammaglobulinemia of infancy (THI) is one of the most common forms of hypogammaglobulinemia in the early childhood. THI is usually associated with chronic, recurrent bacterial and viral infections, life-threatening in some cases, yet its pathogenesis is still largely unknown. As our previous findings indicated the possible role of Treg cells in the pathomechanism of THI, the aim of the current study was to investigate gene expression profile of Treg cells isolated from THI patients. The transcriptome-wide gene profiling was performed using microarray technology on THI patients in two time-points: during (THI-1), and in resolution phase (THI-2) of hypogammaglobulinemia. As a result, a total of 1086 genes were differentially expressed in THI-1 patients, when compared to THI-2 as well as control group. Among them, 931 were up- and 155 downregulated, and part of them encodes genes important for Treg lymphocyte biology and function, i.e. transcription factors/cofactors that regulate FOXP3 expression. Thus, we postulate that Treg cells isolated from THI patients during hypogammaglobulinemia display enhanced suppressor transcriptome signature. Treg expression profile of THI children after normalization of Ig levels largely resembles the results obtained in healthy control group, suggesting THI Treg transcriptome seems to return to that observed in healthy children. Taken together, we suggest that THI pathomechanism is associated not only with transiently elevated Treg cell numbers, but also with their enhanced regulatory/inhibitory functions. These findings expand our knowledge of human Treg cells and may be useful for the future diagnosis or management of THI.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

Selective reprogramming of regulatory T cells in solid tumors can strongly enhance or inhibit tumor growth

Folate receptor delta (FRδ) has been used as a biomarker for regulatory T cells (Tregs), because its expression is limited to Tregs and ovum. Although FRδ is unable to bind folate, we have used molecular docking software to identify a folate congener that binds FRδ with high affinity and have exploited this FRδ-specific ligand to target attached drugs (imaging agents, immune activators, and immune suppressors) specifically to Tregs in murine tumor xenografts. Analysis of treated tumors demonstrates that targeting of a Toll-like receptor 7 agonist inhibits Treg expression of FOXP3, PD-1, CTLA4, and HELIOS, resulting in 40-80% reduction in tumor growth and repolarization of other tumor-infiltrating immune cells to more inflammatory phenotypes. Targeting of the immunosuppressive drug dexamethasone, in contrast, promotes enhanced tumor growth and shifts the tumor-infiltrating immune cells to more anti-inflammatory phenotypes. Since Tregs comprise <1% of cells in the tumor masses examined, and since the targeted drugs are not internalized by cancer cells, these data demonstrate that Tregs exert a disproportionately large effect on tumor growth. Because the targeted drug did not bind to Tregs or other immune cells in healthy tissues, the data demonstrate that the immunosuppressive properties of Tregs in tumors can be manipulated without causing systemic toxicities associated with global reprogramming of the immune system.

Unveiling the potential pleiotropic effects of metformin in treating COVID-19: a comprehensive review

This review article explores the potential of metformin, a medication commonly used for type 2 diabetes, as an antiviral and anti-inflammatory agent in the context of coronavirus disease 2019 (COVID-19). Metformin has demonstrated inhibitory effects on the growth of SARS-CoV-2 in cell culture models and has shown promising results in reducing viral load and achieving undetectable viral levels in clinical trials. Additionally, metformin exhibits anti-inflammatory properties by reducing the production of pro-inflammatory cytokines and modulating immune cell function, which may help prevent cytokine storms associated with severe COVID-19. The drug's ability to regulate the balance between pro-inflammatory Th17 cells and anti-inflammatory Treg cells suggests its potential in mitigating inflammation and restoring T cell functionality. Furthermore, metformin's modulation of the gut microbiota, particularly changes in bacterial taxa and the production of short-chain fatty acids, may contribute to its therapeutic effects. The interplay between metformin, bile acids, the gut microbiome, glucagon-like peptide-1 secretion, and glycemic control has implications for the management of diabetes and potential interventions in COVID-19. By refreshing the current evidence, this review highlights the potential of metformin as a therapeutic option in the management of COVID-19, while also exploring its effects on the gut microbiome and immunometabolism.

Post kala-azar dermal leishmaniasis in the Indian sub-continent: challenges and strategies for elimination

Visceral leishmaniasis (VL) is a severe and often fatal form of leishmaniasis caused by Leishmania donovani in the Indian sub-continent. Post Kala-azar Dermal Leishmaniasis (PKDL) is a late cutaneous manifestation of VL, typically occurring after apparent cure of VL, but sometimes even without a prior history of VL in India. PKDL serves as a significant yet neglected reservoir of infection and plays a crucial role in the transmission of the disease, posing a serious threat to the VL elimination program in the Indian sub-continent. Therefore, the eradication of PKDL should be a priority within the current VL elimination program aimed at achieving a goal of less than 1 case per 10,000 in the population at the district or sub-district levels of VL endemic areas. To accomplish this, a comprehensive understanding of the pathogenesis of PKDL is essential, as well as developing strategies for disease management. This review provides an overview of the current status of diagnosis and treatment options for PKDL, highlighting our current knowledge of the immune responses underlying disease development and progression. Additionally, the review discusses the impact of PKDL on elimination programs and propose strategies to overcome this challenge and achieve the goal of elimination. By addressing the diagnostic and therapeutic gaps, optimizing surveillance and control measures, and implementing effective intervention strategies, it is possible to mitigate the burden of PKDL and facilitate the successful elimination of VL in the Indian sub-continent.

Incretins-Based Therapies and Their Cardiovascular Effects: New Game-Changers for the Management of Patients with Diabetes and Cardiovascular Disease

Atherosclerosis is the leading cause of death worldwide, especially in patients with type 2 diabetes mellitus (T2D). GLP-1 receptor agonists and DPP-4 inhibitors were demonstrated to play a markedly protective role for the cardiovascular system beyond their glycemic control. Several cardiovascular outcome trials (CVOT) reported the association between using these agents and a significant reduction in cardiovascular events in patients with T2D and a high cardiovascular risk profile. Moreover, recent evidence highlights a favorable benefit/risk profile in myocardial infarction and percutaneous coronary revascularization settings. These clinical effects result from their actions on multiple molecular mechanisms involving the immune system, platelets, and endothelial and vascular smooth muscle cells. This comprehensive review specifically concentrates on these cellular and molecular processes mediating the cardiovascular effects of incretins-like molecules, aiming to improve clinicians' knowledge and stimulate a more extensive use of these drugs in clinical practice as helpful cardiovascular preventive strategies.

The Role of Regulatory T Cells in Heart Repair After Myocardial Infarction

Myocardial infarction (MI) remains one of the leading causes of death worldwide. Inflammation and immune responses after MI are of significance to the adverse cardiac remodeling. Regulatory T cells (Tregs) play an important role in suppressing the immune response and thus benefit the post-MI remodeling. After MI, damaged cardiomyocytes may be replaced by scar tissue, leading to systolic and diastolic dysfunction and subsequently adverse remodeling. In this review, we provide an overview of the function and possible mechanisms of Tregs in post-MI heart repair. Specifically, after the occurrence of MI, Tregs infiltrated to peri-infarcted myocardium through CCR5 pathway, CXCR4-CXCL12 axis, and Hippo pathway. Normal functional Tregs can reduce the size of the MI area, improve heart function, and ameliorate myocardial remodeling by inhibiting proinflammatory cells accumulation, changing the proportion of macrophages phenotypes, improving myocardial fibrosis, protecting myocardial cells, and promoting angiogenesis. Eventually, Functional Tregs recruited into the heart can improve MI outcomes. Therefore, targeted therapies with Tregs might provide a promising approach to the treatment of MI remodeling.

Immune resilience despite inflammatory stress promotes longevity and favorable health outcomes including resistance to infection

Some people remain healthier throughout life than others but the underlying reasons are poorly understood. Here we hypothesize this advantage is attributable in part to optimal immune resilience (IR), defined as the capacity to preserve and/or rapidly restore immune functions that promote disease resistance (immunocompetence) and control inflammation in infectious diseases as well as other causes of inflammatory stress. We gauge IR levels with two distinct peripheral blood metrics that quantify the balance between (i) CD8+ and CD4+ T-cell levels and (ii) gene expression signatures tracking longevity-associated immunocompetence and mortality-associated inflammation. Profiles of IR metrics in ~48,500 individuals collectively indicate that some persons resist degradation of IR both during aging and when challenged with varied inflammatory stressors. With this resistance, preservation of optimal IR tracked (i) a lower risk of HIV acquisition, AIDS development, symptomatic influenza infection, and recurrent skin cancer; (ii) survival during COVID-19 and sepsis; and (iii) longevity. IR degradation is potentially reversible by decreasing inflammatory stress. Overall, we show that optimal IR is a trait observed across the age spectrum, more common in females, and aligned with a specific immunocompetence-inflammation balance linked to favorable immunity-dependent health outcomes. IR metrics and mechanisms have utility both as biomarkers for measuring immune health and for improving health outcomes.

Mechanisms regulating the loss of Tregs in HUPO mice that develop spontaneous inflammatory arthritis

T regulatory cells (Tregs) are a potential therapeutic target in many autoimmune diseases including rheumatoid arthritis (RA). The mechanisms responsible for the maintenance of Tregs in chronic inflammatory conditions such as RA are poorly understood. We employed our mouse model of RA in which, the following deletion of Flice-like inhibitory protein in CD11c+ cells, CD11c-FLIP-KO (HUPO) mice develop spontaneous, progressive, erosive arthritis, with reduced Tregs, and the adoptive transfer of Tregs ameliorates the arthritis. HUPO thymic Treg development was normal, but peripheral of Treg Foxp3 was diminished mediated by reduction of dendritic cells and interleukin-2 (IL-2). During chronic inflammatory arthritis Tregs fail to maintain Foxp3, leading to non-apoptotic cell death and conversion to CD4+CD25+Foxp3- cells. Treatment with IL-2 increased Tregs and ameliorated the arthritis. In summary, reduced dendritic cells and IL-2 in the milieu of chronic inflammation, contribute to Treg instability, promoting HUPO arthritis progression, and suggesting a therapeutic approach in RA.

hIgD-Fc-Ig fusion protein regulates T cell functions by inhibiting TCR signaling pathway in adjuvant arthritis rats

This study aimed to investigate the effect of hIgD-Fc-Ig on TCR-Lck-Erk activated by IgD in adjuvant arthritis (AA) rats. Wistar rats were divided into the normal, AA model, hIgD-Fc-Ig (1 mg/kg, 3 mg/kg and 9 mg/kg) and Etanercept (3 mg/kg) groups. The overall index of AA rats was measured every 3 days. The pathologic examination of knee joints and the proliferation of the spleen and thymus of AA rats were detected by H&E staining and CCK-8. The blood flow signal of knee joints of experimental rats was examined by US. The articular bone injury was detected by X-ray. The changes in PBMCs and spleen T cell subsets were detected by flow cytometry. The expression of CD3ε, p-Lck, p-Zap70, Ras, and p-Erk in rat spleens was detected by immunofluorescence and WB. Rat spleen T cells or Jurkat cells treated by IgD to observe the effect of hIgD-Fc-Ig on TCR and its downstream protein expression. The results showed that hIgD-Fc-Ig had a therapeutic effect on AA rats by reducing the secondary inflammation, improving pathological changes. hIgD-Fc-Ig can reduce the ratio of Th cells of PBMCs of AA rats, the ratio of Th, Th1, Th17 cells and increase the ratio of Th2, Treg cells of AA rat spleens. hIgD-Fc-Ig could down-regulate the expression of CD3ε, p-Lck, p-Zap70, Ras, p-Erk in vivo or in vitro. In conclusion, hIgD-Fc-Ig could alleviate the symptoms of AA rats and regulate T cells through TCR-Lck-Erk signaling pathway and maybe a new promising biological agent for RA.

Analysis of Th-cell subsets in local and systemic environments from experimental periodontitis rats

OBJECTIVES

The objective of this study was to explore the effect of periodontitis on Th-cell subsets in local and systemic environments.

METHODS

A total of 32 male Sprague-Dawley rats were randomly divided into periodontitis and control groups. Silk ligatures were applied to the mandibular first (M1) molars in the periodontitis group. Inflammation and alveolar bone loss around the M1 molars were analyzed by histological staining and microcomputed tomography. The mRNA expression of interferon-γ (IFN-γ), interleukin 4 (IL-4), IL-17, and IL-10 in the gingiva was measured by qRT-PCR. The proportions of Th1, Th2, Th17, and Treg cells in the submandibular lymph nodes, peripheral blood, and jaw bone marrow were tested using flow cytometry.

RESULTS

More inflammatory cells and alveolar bone resorption were found in the periodontitis group, with upregulated mRNA expression of IFN-γ, IL-17, and IL-10. The proportion of Th1 and Th17 cells was significantly elevated in submandibular lymph nodes, and the proportion of Th1, Th2, and Th17 cells was significantly elevated in peripheral blood, while the proportion of Th1, Th17, and Treg cells was significantly elevated in jaw bone marrow in the periodontitis group.

CONCLUSION

This study suggests that periodontitis affects the differentiation of Th-cell subsets in both local and systemic environments, resulting in an increased proportion of proinflammatory cells.

Linking dysbiosis to precancerous stomach through inflammation: Deeper than and beyond imaging

Upper gastrointestinal endoscopy is considered the gold standard for gastric lesions detection and surveillance, but it is still associated with a non-negligible rate of missing conditions. In the Era of Personalized Medicine, biomarkers could be the key to overcome missed lesions or to better predict recurrence, pushing the frontier of endoscopy to functional endoscopy. In the last decade, microbiota in gastric cancer has been extensively explored, with gastric carcinogenesis being associated with progressive dysbiosis. Helicobacter pylori infection has been considered the main causative agent of gastritis due to its interference in disrupting the acidic environment of the stomach through inflammatory mediators. Thus, does inflammation bridge the gap between gastric dysbiosis and the gastric carcinogenesis cascade and could the microbiota-inflammation axis-derived biomarkers be the answer to the unmet challenge of functional upper endoscopy? To address this question, in this review, the available evidence on the role of gastric dysbiosis and chronic inflammation in precancerous conditions of the stomach is summarized, particularly targeting the nuclear factor-κB (NF-κB), toll-like receptors (TLRs) and cyclooxygenase-2 (COX-2) pathways. Additionally, the potential of liquid biopsies as a non-invasive source and the clinical utility of studied biomarkers is also explored. Overall, and although most studies offer a mechanistic perspective linking a strong proinflammatory Th1 cell response associated with, but not limited to, chronic infection with Helicobacter pylori, promising data recently published highlights not only the diagnostic value of microbial biomarkers but also the potential of gastric juice as a liquid biopsy pushing forward the concept of functional endoscopy and personalized care in gastric cancer early diagnosis and surveillance.

Changes in expression levels of immune cells and inflammatory cytokines in pre-eclampsia patients before and after delivery

OBJECTIVE

By analyze the expression levels of immune cells and cytokines secreted by preeclampsia patients before and after delivery. Furthermore, to determine the inflammatory and immunological mechanism responsible for preeclampsia, to provide better future prevention and treatment.

METHODS

Twenty-one preeclampsia-diagnosed pregnant women were involved in this study as an observation group. Twenty pregnant women with no history of PE, age-matched, were added to the control group. Thirty NP women, age-matched were included as the reference. The levels of cytokines secreted by T, B, NK and Treg immune cells and Th1, Th2 and Th17 cells were detected before and after delivery.

RESULTS

The number of CD3 + cells in women without preeclampsia before delivery was not statistically different from that in PE patients, but the number of CD4 + and CD8 + cells was lower than that in women without preeclampsia. After delivery, CD4 + cells were larger than those in pregnant women without preeclampsia, while CD8 + cells were smaller than those in pregnant women without preeclampsia. The level of cytokines secreted by Th1 in pregnant women without preeclampsia before delivery was higher than that in PE patients. The levels of cytokines produced by Th1, Th2 and Th17 cells before and after delivery were higher in pregnant women without preeclampsia than in NP women, while Th2 and Th17 were in PE group.

CONCLUSION

PE patients may reduce CD4 + cells and CD8 + cells, and down-regulate the level of cytokines (especially TNF-β) secreted by Th1 cells to reduce the maternal rejection of embryos, thereby reducing the risk of premature delivery, which is a protective adaptive compensation mechanism in favor of embryos.

FOXP3+ regulatory T cells use heparanase to access IL-2 bound to ECM in inflamed tissues

FOXP3+ regulatory T cells (Treg) depend on exogenous IL-2 for their survival and function, but circulating levels of IL-2 are low, making it unclear how Treg access this critical resource in vivo. Here, we show that Treg use heparanase (HPSE) to access IL-2 sequestered by heparan sulfate (HS) within the extracellular matrix (ECM) of inflamed central nervous system tissue. HPSE expression distinguishes human and murine Treg from conventional T cells and is regulated by the availability of IL-2. HPSE-/- Treg have impaired stability and function in vivo, including the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis. Conversely, endowing Treg with HPSE enhances their ability to access HS-sequestered IL-2 and their tolerogenic function in vivo. Together, these data identify novel roles for HPSE and the ECM in immune tolerance, providing new avenues for improving Treg-based therapy of autoimmunity.

Emerging treatments for myelodysplastic syndromes: Biological rationales and clinical translation

Myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by myeloid dysplasia, peripheral blood cytopenias, and increased risk of progression to acute myeloid leukemia (AML). The standard of care for patients with MDS is hypomethylating agent (HMA)-based therapy; however, nearly 50% of patients have no response to the treatment. Patients with MDS in whom HMA therapy has failed have a dismal prognosis and no approved second-line therapy options, so enrollment in clinical trials of experimental agents represents these patients' only chance for improved outcomes. A better understanding of the molecular and biological mechanisms underpinning MDS pathogenesis has enabled the development of new agents that target molecular alterations, cell death regulators, signaling pathways, and immune regulatory proteins in MDS. Here, we review novel therapies for patients with MDS in whom HMA therapy has failed, with an emphasis on the biological rationale for these therapies' development.

Insulin Receptor Substrate 1 Signaling Inhibits Foxp3 Expression and Suppressive Functions in Treg Cells through the mTORC1 Pathway

Regulatory T (Treg) cells play an important role in immune homeostasis by inhibiting cells within the innate and adaptive immune systems; therefore, the stability and immunosuppressive function of Treg cells need to be maintained. In this study, we found that the expression of insulin receptor substrate 1 (IRS1) by Treg cells was lower than that by conventional CD4 T cells. IRS1-overexpressing Treg cells showed the downregulated expression of FOXP3, as well as Treg signature markers CD25 and CTLA4. IRS1-overexpressing Treg cells also showed diminished immunosuppressive functions in an in vitro suppression assay. Moreover, IRS1-overexpressing Treg cells were unable to suppress the pathogenic effects of conventional T cells in a transfer-induced colitis model. IRS1 activated the mTORC1 signaling pathway, a negative regulator of Treg cells. Moreover, IRS1 destabilized Treg cells by upregulating the expression of IFN-γ and Glut1. Thus, IRS1 acts as a negative regulator of Treg cells by downregulating the expression of FOXP3 and disrupting stability.

Antibody-based cancer immunotherapy by targeting regulatory T cells

Regulatory T cells (Tregs) are among the most abundant suppressive cells, which infiltrate and accumulate in the tumor microenvironment, leading to tumor escape by inducing anergy and immunosuppression. Their presence has been correlated with tumor progression, invasiveness and metastasis. Targeting tumor-associated Tregs is an effective addition to current immunotherapy approaches, but it may also trigger autoimmune diseases. The major limitation of current therapies targeting Tregs in the tumor microenvironment is the lack of selective targets. Tumor-infiltrating Tregs express high levels of cell surface molecules associated with T-cell activation, such as CTLA4, PD-1, LAG3, TIGIT, ICOS, and TNF receptor superfamily members including 4-1BB, OX40, and GITR. Targeting these molecules often attribute to concurrent depletion of antitumor effector T-cell populations. Therefore, novel approaches need to improve the specificity of targeting Tregs in the tumor microenvironment without affecting peripheral Tregs and effector T cells. In this review, we discuss the immunosuppressive mechanisms of tumor-infiltrating Tregs and the status of antibody-based immunotherapies targeting Tregs.

GLP-1 receptor agonist as a modulator of innate immunity

Glucagon-like peptide-1 (GLP-1) is a 30-amino acid hormone secreted by L cells in the distal ileum, colon, and pancreatic α cells, which participates in blood sugar regulation by promoting insulin release, reducing glucagon levels, delaying gastric emptying, increasing satiety, and reducing appetite. GLP-1 specifically binds to the glucagon-like peptide-1 receptor (GLP-1R) in the body, directly stimulating the secretion of insulin by pancreatic β-cells, promoting proliferation and differentiation, and inhibiting cell apoptosis, thereby exerting a glycemic lowering effect. The glycemic regulating effect of GLP-1 and its analogues has been well studied in human and murine models in the circumstance of many diseases. Recent studies found that GLP-1 is able to modulate innate immune response in a number of inflammatory diseases. In the present review, we summarize the research progression of GLP-1 and its analogues in immunomodulation and related signal pathways.

Effects of the In Ovo and Dietary Supplementation of L-Ascorbic Acid on the Growth Performance, Inflammatory Response, and Eye L-Ascorbic Acid Concentrations in Ross 708 Broiler Chickens

Simple Summary

L-ascorbic acid (L-AA), known as vitamin C, is involved in several metabolic process, including bone formation, antioxidant activity, and inflammatory response. It is well documented that the antioxidant capacity and immunity of broilers are enhanced in response to the dietary or in ovo administration of L-AA. The aim of the current study was to determine the effects the in ovo or dietary administration of L-AA on the post hatch performance, plasma nitric oxide, and eye L-AA concentrations of Ross 708 broilers. At 17 days of incubation, the following treatments were administered: non-injected or sham-injected (100 μL of saline) controls, or the injection of either 12 or 25 mg of L-AA suspended in 100 μL of saline. In addition, chicks were fed a commercial diet with or without 200 mg/kg of supplemental L-AA. The results of the current study revealed that the eye concentrations of L-AA were higher in males in comparison to females. Additionally, 12 mg of L-AA decreased plasma nitric oxide levels in 14-day-old male broilers in comparison to all the other in ovo injection treatment groups. Compared to a commercial diet, dietary L-AA lowered feed conversion ratio during the second week of post hatch growth. In conclusion, the in ovo administration of L-AA was more effective in reducing inflammatory response, whereas the dietary source had a greater impact on the live performance of broilers. Further research is needed to determine the aforementioned effects throughout the entire growing phase.

Abstract

Effects of the dietary and in ovo administration of L-ascorbic acid (L-AA) on the performance, plasma nitric oxide, and eye L-AA concentrations of Ross 708 broilers were investigated. At 17 days of incubation, live embryonated hatching eggs were randomly assigned to a non-injected or sham-injected (100 μL of saline) control group, or a group injected with either 12 or 25 mg of L-AA suspended in 100 μL of saline. Chicks received a commercial diet with or without 200 mg/kg of supplemental L-AA and were randomly assigned to each of 6 replicate floor pens in each in ovo injection-dietary treatment combination. Weekly live performance variables through 14 days of post hatch age (doa) and the eye weights in both sexes at 0, 7, and 14 doa were determined. At 0 and 14 doa, plasma nitric oxide levels and eye L-AA concentrations of one bird of each sex in each pen were determined. Dietary supplemental L-AA decreased feed intake and growth between 0 and 7 doa, but from 8 to 14 doa; all birds fed supplemental L-AA had a lower feed conversion ratio. At 14 doa, male chicks had higher eye L-AA concentrations and lower plasma nitric oxide levels when treated in ovo with 12 mg of L-AA. In conclusion, dietary L-AA may be used to improve feed conversion in the second week of broiler post hatch growth. However, the in ovo administration of 12 mg of L-AA can increase male eye L-AA concentrations and is effective in reducing their general inflammatory response.

Targeting Strategies for Aberrant Lipid Metabolism Reprogramming and the Immune Microenvironment in Esophageal Cancer: A Review

Esophageal cancer is of high importance to occurrence, development, and treatment resistance. As evidenced by recent studies, pathways (e.g., Wnt/β-catenin, AMPK, and Hippo) are critical to the proliferation, differentiation, and self-renewal of esophageal cancer. In addition, the above pathways play a certain role in regulating esophageal cancer and act as potential therapeutic targets. Over the past few years, the function of lipid metabolism in controlling tumor cells and immune cells has aroused extensive attention. It has been reported that there are intricate interactions between lipid metabolism reprogramming between immune and esophageal cancer cells, whereas molecular mechanisms should be studied in depth. Immune cells have been commonly recognized as a vital player in the esophageal cancer microenvironment, having complex crosstalk with cancer cells. It is increasingly evidenced that the function of immune cells in the tumor microenvironment (TME) is significantly correlated with abnormal lipid metabolism. In this review, the latest findings in lipid metabolism reprogramming in TME are summarized, and the above findings are linked to esophageal cancer progression. Aberrant lipid metabolism and associated signaling pathways are likely to serve as a novel strategy to treat esophageal cancer through lipid metabolism reprogramming.

Analysis of expression of regulatory T cell related lncRNAs in inflammatory demyelinating polyneuropathies

Long non-coding RNAs that regulate function of regulatory T cells can affect pathoetiology of autoimmune disorders, such as inflammatory demyelinating polyneuropathies. In the current case-control study, we compared expression of four of these lncRNAs, namely FLICR, NEST, RMRP and TH2-LCR between patients with inflammatory demyelinating polyneuropathies and healthy subjects. Expressions of RMRP, NEST and FLICR were higher in total patients compared with controls. However, there was no significant difference in their expressions between acute and chronic demyelinating polyneuropathies. In addition, interaction of gender and disease factors had significant effect on expression levels of RMRP and TH2-LCR genes in subgroups. RMRR was superior to other lncRNAs in terms of AUC, sensitivity and specificity values in total patients and both subgroups of patients. This lncRNA could separate total patients, female patients and male patients from corresponding controls with AUC values (±SD) of 0.9 ± 0.03, 0.86 ± 0.07 and 0.93 ± 0.03, respectively. FLICR ranked second in this regard, since it could separate total patients, female patients and male patients from corresponding controls with AUC values (±SD) of 0.81 ± 0.03, 0.72 ± 0.07 and 0.87 ± 0.04, respectively. Therefore, our study provides evidence for participation of regulatory T cells-related lncRNAs in the pathoetiology of inflammatory demyelinating polyneuropathies.

The Effects of Tamoxifen on Tolerogenic Cells in Cancer

Simple Summary

Tamoxifen is a very well-known hormonal therapy used to treat breast cancer patients. It works by blocking the effects of estrogen in breast tissue by competing with estradiol (E₂) in the receptor site and binding to DNA to inhibit carcinogenesis. Moreover, it is less clarified that TAM is also involved indirectly via a Foxp3 knockout model through the CreER system to target specific immune checkpoints, especially checkpoints arising in cancer therapy. The suppressive function of tolerogenic cells is very important in the TME. Hence, in our study, we observed the effects of TAM on Tregs, in which it is involved indirectly via the CreER system. In addition, we also review the effects of TAM on other cells, which are MDSCs and DCs, that act by bridging the innate and adaptive immune systems.

Abstract

Tamoxifen (TAM) is the most prescribed selective estrogen receptor modulator (SERM) to treat hormone-receptor-positive breast cancer patients and has been used for more than 20 years. Its role as a hormone therapy is well established; however, the potential role in modulating tolerogenic cells needs to be better clarified. Infiltrating tumor-microenvironment-regulatory T cells (TME-Tregs) are important as they serve a suppressive function through the transcription factor Forkhead box P3 (Foxp3). Abundant studies have suggested that Foxp3 regulates the expression of several genes (CTLA-4, PD-1, LAG-3, TIM-3, TIGIT, TNFR2) involved in carcinogenesis to utilize its tumor suppressor function through knockout models. TAM is indirectly concomitant via the Cre/loxP system by allowing nuclear translocation of the fusion protein, excision of the floxed STOP cassette and heritable expression of encoding fluorescent protein in a cohort of cells that express Foxp3. Moreover, TAM administration in breast cancer treatment has shown its effects directly through MDSCs by the enrichment of its leukocyte populations, such as NK and NKT cells, while it impairs the differentiation and activation of DCs. However, the fundamental mechanisms of the reduction of this pool by TAM are unknown. Here, we review the vital effects of TAM on Tregs for a precise mechanistic understanding of cancer immunotherapies.

The Multi-Functional Roles of CCR7 in Human Immunology and as a Promising Therapeutic Target for Cancer Therapeutics

An important hallmark of the human immune system is to provide adaptive immunity against pathogens but tolerance toward self-antigens. The CC-chemokine receptor 7 (CCR7) provides a significant contribution in guiding cells to and within lymphoid organs and is important for acquiring immunity and tolerance. The CCR7 holds great importance in establishing thymic architecture and function and naïve and regulatory T-cell homing in the lymph nodes. Similarly, the receptor is a key regulator in cancer cell migration and the movement of dendritic cells. This makes the CCR7 an important receptor as a drug and prognostic marker. In this review, we discussed several biological roles of the CCR7 and its importance as a drug and prognostic marker.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

A novel lipidic peptide with potential to promote balanced effector-regulatory T cell responses

T cell-dendritic cell (DC) interactions contribute to reciprocal stimulation leading to DC maturation that results in production of interleukin-12 (IL-12) and interferon-gamma (IFN-γ). Both cytokines have been implicated in autoimmune diseases while being necessary for effective immune responses against foreign antigens. We describe a lipidic peptide, designated IK14004, that modifies crosstalk between T cells and DCs resulting in suppression of IL-12p40/IFN-γ production. T cell production of interleukin-2 (IL-2) and IFN-γ is uncoupled and IL-12p70 production is enhanced. IK14004 induces expression of activating co-receptors in CD8+ T cells and increases the proportion of Foxp3-expressing CD4+ T regulatory cells. The potential for IK14004 to impact on signalling pathways required to achieve a balanced immune response upon stimulation of DCs and T cells is highlighted. This novel compound provides an opportunity to gain further insights into the complexity of T cell-DC interactions relevant to autoimmunity associated with malignancies and may have therapeutic benefit.

New insights for regulatory T cell in lupus nephritis

Lupus nephritis (LN) is a complicated autoimmune disease marked by out-of-balance of immunological reactivity and immune tolerance. With the advance of immunotherapy in human disease, regulatory T (Treg) cells serve a crucial function in immune tolerance regulation and are characterized with suppression function as one of the most important research hotspots for autoimmunity diseases. In recent years, Treg cells have shown the robust potential for treatment to autoimmunity diseases like type I diabetic mellitus and rheumatoid arthritis. However, Treg cell therapy is poorly understood for LN patients. This review aims to summarize new insights for Treg-targeting techniques in LN patients. The current data regarding the biology features of Treg cells in LN patients is discussed. The propotion of Treg cells in LN patients have contradictory results regarding the use of different molecular markers. Forkhead box protein 3 (FOXP3) are hallmarks for control function of Treg cells. Treg cells can directly or indirectly target T cells and B cells by playing supressive role. The molecular targets for Treg cells in LN patients includes gene variants, miRNAs, and inflammatory related factors. Based on the current knowledge of Treg cell biology, several therapeutic strategies could be used to treat LN: cell transplantation, low dose IL-2 treatment, drugs target the balance of Treg and type 17 T helper (Th17) cells, and Chinese medicine.

Tumor-Associated Regulatory T Cells in Non-Small-Cell Lung Cancer: Current Advances and Future Perspectives

Non-small-cell lung cancer (NSCLC) is one of the most threatening malignant tumors to human health, with the overall 5-year survival rate being less than 30%. Regulatory T cells (Tregs), a functional subset of T cells, maintain immunologic immunological self-tolerance and homeostasis. Accumulating evidence has uncovered their implicated roles in various cancers in recent years. In NSCLC, they are associated with staging, therapeutic efficacy, and prognosis by infiltrating in tissues and thereby attenuating immunologic anticancer effects in patients. Tumor-associated Tregs display distinct immune signatures in NSCLC compared to thymus-derived Tregs, playing an important role in remodeling the tumor microenvironment (TME). Targeting Tregs has become a novel direction for NSCLC patients, such as disrupting their immune-suppressive functions, blocking their trafficking into tumors, and inhibiting their development and/or activation. This review is aimed at elucidating the molecular mechanisms of tumor-associated Tregs in NSCLC and providing therapeutic targets relevant to Tregs.

Mucosal viral infection induces a regulatory T cell activation phenotype distinct from tissue residency in mouse and human tissues

Regulatory T cells (Tregs) mediate immune homeostasis, yet also facilitate nuanced immune responses during infection, balancing pathogen control while limiting host inflammation. Recent studies have identified Treg populations in non-lymphoid tissues that are phenotypically distinct from Tregs in lymphoid tissues (LT), including performance of location-dependent roles. Mucosal tissues serve as critical barriers to microbes while performing unique physiologic functions, so we sought to identify distinct phenotypical and functional aspects of mucosal Tregs in the female reproductive tract. In healthy human and mouse vaginal mucosa, we found that Tregs are highly activated compared to blood or LT Tregs. To determine if this phenotype reflects acute activation or a general signature of vaginal tract (VT)-residency, we infected mice with HSV-2 to discover that VT Tregs express granzyme-B (GzmB) and acquire a VT Treg signature distinct from baseline. To determine the mechanisms that drive GzmB expression, we performed ex vivo assays to reveal that a combination of type-I interferons and interleukin-2 is sufficient for GzmB expression. Together, we highlight that VT Tregs are activated at steady state and become further activated in response to infection; thus, they may exert robust control of local immune responses, which could have implications for mucosal vaccine design.

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.

IL-6 and TNFα Drive Extensive Proliferation of Human Tregs Without Compromising Their Lineage Stability or Function

Treg therapies are being tested in clinical trials in transplantation and autoimmune diseases, however, the impact of inflammation on Tregs remains controversial. We challenged human Tregs ex-vivo with pro-inflammatory cytokines IL-6 and TNFα and observed greatly enhanced proliferation stimulated by anti-CD3 and anti-CD28 (aCD3/28) beads or CD28 superagonist (CD28SA). The cytokine-exposed Tregs maintained high expression of FOXP3 and HELIOS, demethylated FOXP3 enhancer, and low IFNγ, IL-4, and IL-17 secretion. Blocking TNF receptor using etanercept or deletion of TNF receptor 2 using CRISPR/Cas9 blunted Treg proliferation and attenuated FOXP3 and HELIOS expression. These results prompted us to consider using CD28SA together with IL-6 and TNFα without aCD3/28 beads (beadless) as an alternative protocol for therapeutic Treg manufacturing. Metabolomics profiling revealed more active glycolysis and oxidative phosphorylation, increased energy production, and higher antioxidant potential during beadless Treg expansion. Finally, beadless expanded Tregs maintained suppressive functions in vitro and in vivo. These results demonstrate that human Tregs positively respond to proinflammatory cytokines with enhanced proliferation without compromising their lineage identity or function. This property can be harnessed for therapeutic Treg manufacturing.

AMP-activated protein kinase alpha1 promotes tumor development via FOXP3 elevation in tumor-infiltrating Treg cells

Overwhelming evidence indicates that infiltration of tumors by Treg cells with elevated levels of FOXP3 suppresses the host antitumor immune response. However, the molecular mechanisms that maintain high expression of FOXP3 in tumor-infiltrating Treg cells remain elusive. Here, we report that AMP-activated protein kinase alpha1 (AMPKα1) enables high FOXP3 expression in tumor-infiltrating Treg cells. Mice with Treg-specific AMPKα1 deletion showed delayed tumor progression and enhanced antitumor T cell immunity. Further experiments showed that AMPKα1 maintains the functional integrity of Treg cells and prevents interferon-γ production in tumor-infiltrating Treg cells. Mechanistically, AMPKα1 maintains the protein stability of FOXP3 in Treg cells by downregulating the expression of E3 ligase CHIP (STUB1). Our results suggest that AMPKα1 activation promotes tumor growth by maintaining FOXP3 stability in tumor-infiltrating Treg cells and that selective inhibition of AMPK in Treg cells might be an effective anti-tumor therapy.

Mucosal tissue regulatory T cells are integral in balancing immunity and tolerance at portals of antigen entry

Foxp3+ regulatory T cells (Tregs) are a subset of CD4+ T cells that exert suppressive control over other immune cells. Tregs are critical for preventing systemic autoimmunity and maintaining peripheral tolerance, and yet they also assist in orchestration of immunity to pathogenic insult, wherein they limit collateral immunopathology and assist in facilitating a fine balance between immune tolerance and effector activity. Tregs have been extensively studied in lymphoid tissues, and a growing body of work has characterized phenotypically distinct Tregs localized in various nonlymphoid tissue compartments. These tissue Tregs can perform location-specific, alternative functions, highlighting their dynamic, context-dependent roles. Tregs have also been identified in mucosal tissues where specialized physiological functions are paramount, including helping the host to respond appropriately to pathogenic versus innocuous antigens that are abundant at mucosal portals of antigen entry. As in other tissue Treg compartments, mucosal Tregs in the respiratory, gastrointestinal, and genitourinary tracts are distinct from circulating counterparts and can carry out mucosa-specific functions as well as classic suppressive functions that are the hallmark of Tregs. In this review, we summarize current knowledge regarding mucosal Tregs in both health and disease.

TNFR2 depletion reduces psoriatic inflammation in mice via downregulating specific dendritic cell populations in lymph nodes and inhibiting IL-23/IL-17 pathways

TNF-α, a proinflammatory cytokine, is a crucial mediator of psoriasis pathogenesis. TNF-α functions by activating TNFR1 and TNFR2. Anti-TNF drugs that neutralize TNF-α, thus blocking the activation of TNFR1 and TNFR2, have been proven highly therapeutic in psoriatic diseases. TNF-α also plays an important role in host defense; thus, anti-TNF therapy can cause potentially serious adverse effects, including opportunistic infections and latent tuberculosis reactivation. These adverse effects are attributed to TNFR1 inactivation. Therefore, understanding the relative contributions of TNFR1 and TNFR2 has clinical implications in mitigating psoriasis versus global TNF-α blockade. We found a significant reduction in psoriasis lesions as measured by epidermal hyperplasia, characteristic gross skin lesion, and IL-23 or IL-17A levels in Tnfr2-knockout but not in Tnfr1-knockout mice in the imiquimod psoriasis model. Furthermore, imiquimod-mediated increase in the myeloid dendritic cells, TNF/inducible nitric oxide synthase‒producing dendritic cells, and IL-23 expression in the draining lymph nodes were dependent on TNFR2 but not on TNFR1. Together, our results support that psoriatic inflammation is not dependent on TNFR1 activity but is driven by a TNFR2-dependent IL-23/IL-17 pathway activation. Thus, targeting the TNFR2 pathway may emerge as a potential next-generation therapeutic approach for psoriatic diseases.

Regulation of T-Cell Immune Responses by Pro-Resolving Lipid Mediators

Both the initiation and the resolution of inflammatory responses are governed by the sequential activation, migration, and control/suppression of immune cells at the site of injury. Bioactive lipids play a major role in the fine-tuning of this dynamic process in a timely manner. During inflammation and its resolution, polymorphonuclear cells (PMNs) and macrophages switch from producing pro-inflammatory prostaglandins and leukotrienes to specialized pro-resolving lipid mediators (SPMs), namely, lipoxins, resolvins, protectins, and maresins, which are operative at the local level to limit further inflammation and tissue injury and restore homeostasis. Accumulating evidences expand now the role and actions of these lipid mediators from innate to adaptive immunity. In particular, SPMs have been shown to contribute to the control of chronic inflammation, and alterations in their production and/or function have been associated with the persistence of several pathological conditions, including autoimmunity, in human and experimental models. In this review, we focus on the impact of pro-resolving lipids on T cells through their ability to modulate T-cell responses. In particular, the effects of the different families of SPMs to restrain effector T-cell functions while promoting regulatory T cells will be reviewed, along with the underlying mechanisms. Furthermore, the emerging concept of SPMs as new biological markers for disease diagnostic and progression and as putative therapeutic tools to regulate the development and magnitude of inflammatory and autoimmune diseases is discussed.

The effect of probiotic supplementation on systemic inflammation in dialysis patients

Background

Emerging evidence suggests that intestinal dysbiosis contributes to systemic inflammation and cardiovascular diseases in dialysis patients. The purpose of this study was to evaluate the effects of probiotic supplementation on various inflammatory parameters in hemodialysis (HD) patients.

Methods

Twenty-two patients with maintenance HD were enrolled. These patients were treated twice a day with 2.0 ×1010 colony forming units of a combination of Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 3 months. The microbiome and fecal short-chain fatty acids (SCFAs) were analyzed. The percentages of CD14+ CD16+ proinflammatory monocytes and CD4+ CD25+ regulatory T-cells (Tregs) before and after probiotic supplementation were determined by flow cytometry. Serum levels of calprotectin and cytokine responses upon lipopolysaccharide (LPS) challenge were compared before and after probiotic supplementation.

Results

Fecal SCFAs increased significantly after probiotic supplementation. Serum levels of calprotectin and interleukin 6 upon LPS stimulation significantly decreased. The anti-inflammatory effects of probiotics were associated with a significant increase in the percentage of CD4+ CD25+ Tregs (3.5% vs. 8.6%, p < 0.05) and also with a decrease of CD14+ CD16+ proinflammatory monocytes (310/mm2 vs. 194/mm2, p < 0.05).

Conclusion

Probiotic supplementation reduced systemic inflammatory responses in HD patients and this effect was associated with an increase in Tregs and a decrease in proinflammatory monocytes. Hence, targeting intestinal dysbiosis might be a novel strategy for decreasing inflammation and cardiovascular risks in HD patients.

A regulatory T cell signature distinguishes the immune landscape of COVID-19 patients from those with other respiratory infections

Despite recent studies of immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), little is known about how the immune response against SARS-CoV-2 differs from other respiratory infections. We compare the immune signature from hospitalized SARS-CoV-2–infected patients to patients hospitalized prepandemic with influenza or respiratory syncytial virus (RSV). Our in-depth profiling indicates that the immune landscape in SARS-CoV-2 patients is largely similar to flu or RSV patients. Unique to patients infected with SARS-CoV-2 who had the most critical clinical disease were changes in the regulatory T cell (T_reg) compartment. A T_reg signature including increased frequency, activation status, and migration markers was correlated COVID-19 severity. These findings are relevant as T_regs are considered for therapy to combat the severe inflammation seen in COVID-19 patients. Likewise, having defined the overlapping immune landscapes in SARS-CoV-2, existing knowledge of flu and RSV infections could be leveraged to identify common treatment strategies.