Interleukin-2 signaling via STAT5 constrains T helper 17 cell generation

Protein Kinase CK2 Maintains Reciprocal Balance Between Th17 and Treg Cells in the Pathogenesis of UC

BACKGROUND

T helper 17 and regulatory T cells balance have crucial effects on the development of ulcerative colitis (UC). Currently, how to break this balance has not yet been found. Protein kinase CK2 is involved in the pathogenesis of immune-related disorders. However, its effects on the development of UC are obscure.

METHODS

The level of CK2 in the colonic tissues of UC patients was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and immune-histochemistry. Peripheral blood CD4+ T cells were treated with CK2 inhibitor CX4945 or transfected with Csnk2-interfering lentivirus; the mRNA expression and protein levels of inflammatory cytokines were detected by qRT-PCR, enzyme-linked immunosorbent assay, and flow cytometry. Moreover, CX4945 was administered to trinitrobenzene sulfonic acid (TNBS)-induced colitis mice model for determining the function of CK2 on the regulation of intestinal inflammation.

RESULTS

The CK2 level was markedly increased in inflamed mucosa of UC and highly expressed in CD4+ T cells. Blockade of CK2 by CX4945 inhibited Th17 but promoted regulatory T-cell (Treg) immune responses in CD4+ T cells from patients with UC. Moreover, CK2 blockade alleviated TNBS-induced colitis in mice. Inhibition of CK2 suppressed Th17 but promoted Treg differentiation by decreasing the phosphorylation level of signal transducer and activator of transcription (STAT) 3 and increasing the phosphorylation level of STAT5. The RNA-Seq and co-immunoprecipitation analysis further showed that CK2 could interact with Sirtuin 1 (SIRT1) and downregulate SIRT1 expression, which participated in Th17 inhibition but promoted Treg differentiation. Sirtuin 1 upregulation ameliorated TNBS-induced colitis, whereas SIRT1 blockade aggravated TNBS-induced colitis in mice.

CONCLUSIONS

CK2 have crucial effects on the development of UC by maintaining reciprocal balance between Th17 and Treg cells. Protein kinase CK2 blockade might be considered as a new therapeutic approach for UC treatment.

The effects of post-translational modifications on Th17/Treg cell differentiation

Regulatory T (Treg) cells and Th17 cells are subsets of CD4⁺ T cells which play an essential role in immune homeostasis and infection. Dysregulation of the Th17/Treg cell balance was shown to be implicated in the development and progression of several disorders such as autoimmune disease, inflammatory disease, and cancer. Multiple factors, including T cell receptor (TCR) signals, cytokines, metabolic and epigenetic regulators can influence the differentiation of Th17 and Treg cells and affect their balance. Accumulating evidence indicates that the activity of key molecules such as forkhead box P3 (Foxp3), the retinoic acid-related orphan receptor gamma t (RORγt), and signal transducer and activator of transcription (STAT)s are modulated by the number of post-translational modifications (PTMs) such as phosphorylation, methylation, nitrosylation, acetylation, glycosylation, lipidation, ubiquitination, and SUMOylation. PTMs might affect the protein folding efficiency and protein conformational stability, and consequently determine protein structure, localization, and function. Here, we review the recent progress in our understanding of how PTMs modify the key molecules involved in the Th17/Treg cell differentiation, regulate the Th17/Treg balance, and initiate autoimmune diseases caused by dysregulation of the Th17/Treg balance. A better understanding of Th17/Treg regulation may help to develop novel potential therapeutics to treat immune-related diseases.

The deacetylase SIRT2 contributes to autoimmune disease pathogenesis by modulating IL-17A and IL-2 transcription

Aberrant IL-17A expression together with reduced IL-2 production by effector CD4⁺ T cells contributes to the pathogenesis of systemic lupus erythematosus (SLE). Here, we report that Sirtuin 2 (SIRT2), a member of the family of NAD⁺-dependent histone deacetylases, suppresses IL-2 production by CD4⁺ T cells while promoting their differentiation into Th17 cells. Mechanistically, we show that SIRT2 is responsible for the deacetylation of p70S6K, activation of the mTORC1/HIF-1α/RORγt pathway and induction of Th17-cell differentiation. Additionally, SIRT2 was shown to be responsible for the deacetylation of c-Jun and histones at the Il-2 gene, resulting in decreased IL-2 production. We found that the transcription factor inducible cAMP early repressor (ICER), which is overexpressed in T cells from people with SLE and lupus-prone mice, bound directly to the Sirt2 promoter and promoted its transcription. AK-7, a SIRT2 inhibitor, limited the ability of adoptively transferred antigen-specific CD4⁺ T cells to cause autoimmune encephalomyelitis in mice and limited disease in lupus-prone MRL/lpr mice. Finally, CD4⁺ T cells from SLE patients exhibited increased expression of SIRT2, and pharmacological inhibition of SIRT2 in primary CD4⁺ T cells from patients with SLE attenuated the ability of these cells to differentiate into Th17 cells and promoted the generation of IL-2-producing T cells. Collectively, these results suggest that SIRT2-mediated deacetylation is essential in the aberrant expression of IL-17A and IL-2 and that SIRT2 may be a promising molecular target for new SLE therapies.

Therapeutic potential of interleukin-2 in autoimmune diseases

Autoimmune diseases are characterized by dysregulation and aberrant activation of cells in the immune system. Therefore, restoration of the immune balance represents a promising therapeutic target in autoimmune diseases. Interleukin-2 (IL-2) can promote the expansion and differentiation of different immune cell subsets dose-dependently. At high doses, IL-2 can promote the differentiation and expansion of effector and memory T cells, whereas at low doses, IL-2 can promote the differentiation, survival, and function of regulatory T (T_reg) cells, a CD4⁺ T cell subset that is essential for the maintenance of immune homeostasis and immune tolerance. Therefore, IL-2 exerts immunostimulatory and immunosuppressive effects in autoimmune diseases. The immunoregulatory role of low-dose IL-2 has sparked excitement for the therapeutic exploration of modulating the IL-2-T_reg axis in the context of autoimmune diseases. In this review, we discuss recent advances in the therapeutic potential of IL-2 or IL-2-derived molecules in the treatment of autoimmune diseases.

Lymph node fibroblastic reticular cells regulate differentiation and function of CD4 T cells via CD25

Lymph node fibroblastic reticular cells (LN-FRCs) provide functional structure to LNs and play important roles in interactions between T cells and antigen-presenting cells. However, the direct impact of LN-FRCs on naive CD4+ T cell differentiation has not been explored. Here, we show that T cell zone FRCs of LNs (LN-TRCs) express CD25, the α chain of the IL-2 receptor heterotrimer. Moreover, LN-TRCs trans-present IL-2 to naive CD4+ T cells through CD25, thereby facilitating early IL-2-mediated signaling. CD25-deficient LN-TRCs exhibit attenuated STAT5 phosphorylation in naive CD4+ T cells during T cell differentiation, promoting T helper 17 (Th17) cell differentiation and Th17 response-related gene expression. In experimental autoimmune disease models, disease severity was elevated in mice lacking CD25 in LN-TRCs. Therefore, our results suggest that CD25 expression on LN-TRCs regulates CD4+ T cell differentiation by modulating early IL-2 signaling of neighboring, naive CD4+ T cells, influencing the overall properties of immune responses.

Targeted Delivery Platforms for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative condition of the central nervous system (CNS) that presents with varying levels of disability in patients, displaying the significance of timely and effective management of this complication. Though several treatments have been developed to protect nerves, comprehensive improvement of MS is still considered an essential bottleneck. Therefore, the development of innovative treatment methods for MS is one of the core research areas. In this regard, nanoscale platforms can offer practical and ideal approaches to the diagnosis and treatment of various diseases, especially immunological disorders such as MS, to improve the effectiveness of conventional therapies. It should be noted that there is significant progress in the development of neuroprotective strategies through the implementation of various nanoparticles, monoclonal antibodies, peptides, and aptamers. In this study, we summarize different particle systems as well as targeted therapies, such as antibodies, peptides, nucleic acids, and engineered cells for the treatment of MS, and discuss their potential in the treatment of MS in the preclinical and clinical stages. Future advances in targeted delivery of medical supplies may offer new strategies for complete recovery as well as practical treatment of progressive forms of MS.

The role of Th17 cells/IL-17A in AD, PD, ALS and the strategic therapy targeting on IL-17A

Neurodegenerative diseases are a group of disorders characterized by progressive loss of certain populations of neurons, which eventually lead to dysfunction. These diseases include Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). Immune pathway dysregulation is one of the common features of neurodegeneration. Recently, there is growing interest in the specific role of T helper Th 17 cells and Interleukin-17A (IL-17A), the most important cytokine of Th 17 cells, in the pathogenesis of the central nervous system (CNS) of neurodegenerative diseases. In the present study, we summarized current knowledge about the function of Th17/IL-17A, the physiology of Th17/IL-17A in diseases, and the contribution of Th17/IL-17A in AD, PD, and ALS. We also update the findings on IL-17A-targeting drugs as potentially immunomodulatory therapeutic agents for neurodegenerative diseases. Although the specific mechanism of Th17/IL-17A in this group of diseases is still controversial, uncovering the molecular pathways of Th17/IL-17A in neurodegeneration allows the identification of suitable targets to modulate these cellular processes. Therapeutics targeting IL-17A might represent potentially novel anti-neurodegeneration drugs.

Bone Morphogenetic Proteins Shape Treg Cells

The transforming growth factor-β (TGF-β) family includes cytokines controlling cell behavior, differentiation and homeostasis of various tissues including components of the immune system. Despite well recognized importance of TGF-β in controlling T cell functions, the immunomodulatory roles of many other members of the TGF-β cytokine family, especially bone morphogenetic proteins (BMPs), start to emerge. Bone Morphogenic Protein Receptor 1α (BMPR1α) is upregulated by activated effector and Foxp3+ regulatory CD4+ T cells (Treg cells) and modulates functions of both of these cell types. BMPR1α inhibits generation of proinflammatory Th17 cells and sustains peripheral Treg cells. This finding underscores the importance of the BMPs in controlling Treg cell plasticity and transition between Treg and Th cells. BMPR1α deficiency in in vitro induced and peripheral Treg cells led to upregulation of Kdm6b (Jmjd3) demethylase, an antagonist of polycomb repressive complex 2 (PRC2), and cell cycle inhibitor Cdkn1a (p21Cip1) promoting cell senescence. This indicates that BMPs and BMPR1α may represent regulatory modules shaping epigenetic landscape and controlling proinflammatory reprogramming of Th and Treg cells. Revealing functions of other BMP receptors and their crosstalk with receptors for TGF-β will contribute to our understanding of peripheral immunoregulation.

IL-2 Signaling Couples the MAPK and mTORC1 Axes to Promote T Cell Proliferation and Differentiation in Teleosts

IL-2 is a pleiotropic cytokine that is critical for T cell immunity. Although the IL-2-mediated regulation of T cell immunity in mammals is relatively well understood, it remains largely unknown whether and how IL-2 regulates T cell immunity in lower vertebrates. To address this knowledge gap, we investigated the role played by IL-2 in the regulation of T cell response, as well as the associated underlying mechanisms in a teleost fish, large yellow croaker (Larimichthys crocea). We found that large yellow croaker (L. crocea) IL-2 (LcIL-2) significantly promoted T cell proliferation both in vivo and in vitro; significantly induced the differentiation of Th1, Th2, regulatory T, and cytotoxic T cells while inhibiting Th17 differentiation; and participated in the elimination of invading pathogenic bacteria. Mechanistically, the binding of LcIL-2 to its heterotrimer receptor complex (LcIL-15Rα/LcIL-2Rβ/Lcγc) triggered the conserved JAK-STAT5 pathway, which in turn regulated the expression of genes involved in T cell expansion, differentiation, and biological function. The MAPK and mammalian target of rapamycin complex 1 (mTORC1) axes, which are involved in TCR-mediated signaling, were also required for LcIL-2-mediated T cell response. Collectively, our results demonstrated that fish IL-2 plays a comprehensive regulatory role in T cell response and highlighted the complex and delicate network regulating T cell-driven immune response. We propose that T cell immunity is regulated by the interplay between TCR signaling and cytokine signaling, and that this basic strategy evolved before the emergence of the tetrapod lineage. Our findings provide valuable insights into the regulatory mechanisms underlying T cell response in teleosts.

IL-17A contributes skeletal muscle atrophy in lung cancer-induced cachexia via JAK2/STAT3 pathway

Cachexia is a complex metabolic syndrome that occurs in approximately 50% of patients with cancer. Skeletal muscle atrophy is the primary clinical feature. Interleukin (IL)-17A, a pro-inflammatory factor, plays an important role in many chronic inflammatory diseases. Here, we describe a novel signaling pathway through which IL-17A induced muscle atrophy.We conducted a retrospective clinical study to investigate the relationship between IL-17A and the skeletal muscle index in patients with lung adenocarcinoma. We also investigated the involvement of JAK2/STAT3 signaling pathway regarding the main features of cachexia by injecting Lewis lung carcinoma (LLC) cells into C57BL/6 mice as a model to replicate cancer-induced cachexia. In vitro, C2C12 myotubes were treated with recombinant IL-17A, anti-IL-17A monoclonal antibody, STAT3 inhibitor AG490, and LLC-conditioned medium. Cell viability and aging was also evaluated. We found in cancer conditions, increased serum levels of IL-17A were related to muscle wasting. JAK2/STAT3 phosphorylation was observed in the muscle of LLC tumor-bearing mice, accompanied by decreased MHC/Myog levels and increased MuRF1/Atrogin-1 levels. Administration of anti-IL-17A monoclonal antibody and AG490 slowed muscle atrophy development. Consistent with the in vivo findings, C2C12 myotubes treated with IL-17A and LLC-conditioned medium demonstrated phosphorylated JAK2/STAT3 signaling, resulting in MHC loss and myotube atrophy. IL-17A also inhibited C2C12 cell proliferation, cell cycle breaking, and cellular senescence. Our results identify phosphorylation of IL-17A/JAK2/STAT3 signaling pathway appears to be an important component in the pathogenesis of LLC tumor-induced cachexia. Targeted therapy of IL-17A may be a promising approach to reduce skeletal muscle loss of patients with cancer.

STAT3 Role in T-Cell Memory Formation

Along with the clinical success of immuno-oncology drugs and cellular therapies, T-cell biology has attracted considerable attention in the immunology community. Long-term immunity, traditionally analyzed in the context of infection, is increasingly studied in cancer. Many signaling pathways, transcription factors, and metabolic regulators have been shown to participate in the formation of memory T cells. There is increasing evidence that the signal transducer and activator of transcription-3 (STAT3) signaling pathway is crucial for the formation of long-term T-cell immunity capable of efficient recall responses. In this review, we summarize what is currently known about STAT3 role in the context of memory T-cell formation and antitumor immunity.

The role of Th17 cells in the pathogenesis and treatment of breast cancer

Breast cancer is a severe problem worldwide due to an increase in mortality and prevalence among women. Despite early diagnostic procedures as well as advanced therapies, more investigation is required to find new treatment targets. Various factors and mechanisms, such as inflammatory conditions, can play a crucial role in cancer progression. Among them, Th17 cells are identified as effective CD4⁺ T cells that play an essential role in autoimmune diseases and inflammation which may be associated with anti-tumor responses. In addition, Th17 cells are one of the main factors involved in cancer, especially breast cancer via the inflammatory process. In tumor immunity, the exact mechanism of Th17 cells is not entirely understood and seems to have a dual function in tumor development. Various studies have reported that cytokines secreted by Th17 cells are in close relation to cancer stem cells and tumor microenvironment. Therefore, they play a critical role in the growth, proliferation, and invasion of tumor cells. On the other hand, most studies have reported that T cells suppress the growth of tumor cells by the induction of immune responses. In patients with breast cancer compared to normal individuals, various studies have been reported that the Th17 population dramatically increases in peripheral blood which results in cancer progression. It seems that Th17 cells by creating inflammatory conditions through the secretion of cytokines, including IL-22, IL-17, TNF-α, IL-21, and IL-6, can significantly enhance breast cancer progression. Therefore, to identify the mechanisms and factors involved in the activation and development of Th17 cells, they can provide an essential role in preventing breast cancer progression. In the present review, the role of Th17 cells in breast cancer progression and its therapeutic potential was investigated.

Anti-inflammatory cytokines in sickle cell disease

Sickle cell disease (SCD) is a well-studied monogenetic disease with an established chronic inflammatory component. The paradigm shift towards inflammation has made the pathophysiology of SCD even more complex. Studies have shown that an imbalance between the pro-inflammatory and anti-inflammatory cytokines in SCD exists; however, the reports are skewed toward the pro-inflammatory mediators. We enumerate recent in vitro and in vivo studies on anti-inflammatory cytokines in SCD patients, and discuss the biology of anti-inflammatory cytokines including the already reported IL-2, TGF-β, and IL-10 as well as the recently discovered IL-27, IL-35 and IL-37. This review will improve the understanding of the pathophysiology of SCD and aid in the search of new therapeutic options for patients with SCD.

Metabolism Characteristics of Th17 and Regulatory T Cells in Autoimmune Diseases

The abnormal number and functional deficiency of immune cells are the pathological basis of various diseases. Recent years, the imbalance of Th17/regulatory T (Treg) cell underlies the occurrence and development of inflammation in autoimmune diseases (AID). Currently, studies have shown that material and energy metabolism is essential for maintaining cell survival and normal functions and the altered metabolic state of immune cells exists in a variety of AID. This review summarizes the biology and functions of Th17 and Treg cells in AID, with emphasis on the advances of the roles and regulatory mechanisms of energy metabolism in activation, differentiation and physiological function of Th17 and Treg cells, which will facilitate to provide targets for the treatment of immune-mediated diseases.

Local inhibition of TGF-β1 signaling improves Th17/Treg balance but not joint pathology during experimental arthritis

TGF-β1 is an important growth factor to promote the differentiation of T helper 17 (Th17) and regulatory T cells (Treg). The potential of TGF-β1 as therapeutic target in T cell-mediated diseases like rheumatoid arthritis (RA) is unclear. We investigated the effect of TGF-β1 inhibition on murine Th17 differentiation in vitro, on human RA synovial explants ex vivo, and on the development of experimental arthritis in vivo. Murine splenocytes were differentiated into Th17 cells, and the effect of the TGF-βRI inhibitor SB-505124 was studied. Synovial biopsies were cultured in the presence or absence of SB-505124. Experimental arthritis was induced in C57Bl6 mice and treated daily with SB-505124. Flow cytometry analysis was performed to measure different T cell subsets. Histological sections were analysed to determine joint inflammation and destruction. SB-505124 potently reduced murine Th17 differentiation by decreasing Il17a and Rorc gene expression and IL-17 protein production. SB-505124 significantly suppressed IL-6 production by synovial explants. In vivo, SB-505124 reduced Th17 numbers, while increased numbers of Tregs were observed. Despite this skewed Th17/Treg balance, SB-505124 treatment did not result in suppression of joint inflammation and destruction. Blocking TGF-β1 signalling suppresses Th17 differentiation and improves the Th17/Treg balance. However, local SB-505124 treatment does not suppress experimental arthritis.

Application of ATAC-Seq for genome-wide analysis of the chromatin state at single myofiber resolution

Myofibers are the main components of skeletal muscle, which is the largest tissue in the body. Myofibers are highly adaptive and can be altered under different biological and disease conditions. Therefore, transcriptional and epigenetic studies on myofibers are crucial to discover how chromatin alterations occur in the skeletal muscle under different conditions. However, due to the heterogenous nature of skeletal muscle, studying myofibers in isolation proves to be a challenging task. Single-cell sequencing has permitted the study of the epigenome of isolated myonuclei. While this provides sequencing with high dimensionality, the sequencing depth is lacking, which makes comparisons between different biological conditions difficult. Here, we report the first implementation of single myofiber ATAC-Seq, which allows for the sequencing of an individual myofiber at a depth sufficient for peak calling and for comparative analysis of chromatin accessibility under various physiological and disease conditions. Application of this technique revealed significant differences in chromatin accessibility between resting and regenerating myofibers, as well as between myofibers from a mouse model of Duchenne Muscular Dystrophy (mdx) and wild-type (WT) counterparts. This technique can lead to a wide application in the identification of chromatin regulatory elements and epigenetic mechanisms in muscle fibers during development and in muscle-wasting diseases.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of "profibrotic" cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

T Helper Cell Lineage-Defining Transcription Factors: Potent Targets for Specific GVHD Therapy?

Allogenic hematopoietic stem cell transplantation (allo-HSCT) represents a potent and potentially curative treatment for many hematopoietic malignancies and hematologic disorders in adults and children. The donor-derived immunity, elicited by the stem cell transplant, can prevent disease relapse but is also responsible for the induction of graft-versus-host disease (GVHD). The pathophysiology of acute GVHD is not completely understood yet. In general, acute GVHD is driven by the inflammatory and cytotoxic effect of alloreactive donor T cells. Since several experimental approaches indicate that CD4 T cells play an important role in initiation and progression of acute GVHD, the contribution of the different CD4 T helper (Th) cell subtypes in the pathomechanism and regulation of the disease is a central point of current research. Th lineages derive from naïve CD4 T cell progenitors and lineage commitment is initiated by the surrounding cytokine milieu and subsequent changes in the transcription factor (TF) profile. Each T cell subtype has its own effector characteristics, immunologic function, and lineage specific cytokine profile, leading to the association with different immune responses and diseases. Acute GVHD is thought to be mainly driven by the Th1/Th17 axis, whereas Treg cells are attributed to attenuate GVHD effects. As the differentiation of each Th subset highly depends on the specific composition of activating and repressing TFs, these present a potent target to alter the Th cell landscape towards a GVHD-ameliorating direction, e.g. by inhibiting Th1 and Th17 differentiation. The finding, that targeting of Th1 and Th17 differentiation appears more effective for GVHD-prevention than a strategy to inhibit Th1 and Th17 cytokines supports this concept. In this review, we shed light on the current advances of potent TF inhibitors to alter Th cell differentiation and consecutively attenuate GVHD. We will focus especially on preclinical studies and outcomes of TF inhibition in murine GVHD models. Finally, we will point out the possible impact of a Th cell subset-specific immune modulation in context of GVHD.

Cellular immune responses in the pathophysiology of preeclampsia

Preeclampsia, defined as new-onset hypertension accompanied by proteinuria occurring at 20 weeks of gestation or later, is a leading cause of perinatal morbidity and mortality worldwide. The pathophysiology of this major multi-systemic syndrome includes defective deep placentation, oxidative stress, endothelial dysfunction, the presence of an anti-angiogenic state, and intravascular inflammation, among others. In this review, we provide a comprehensive overview of the cellular immune responses involved in the pathogenesis of preeclampsia. Specifically, we summarize the role of innate and adaptive immune cells in the maternal circulation, reproductive tissues, and at the maternal-fetal interface of women affected by this pregnancy complication. The major cellular subsets involved in the pathogenesis of preeclampsia are regulatory T cells, effector T cells, NK cells, monocytes, macrophages, and neutrophils. We also summarize the literature on those immune cells that have been less characterized in this clinical condition, such as γδ T cells, invariant natural killer T cells, dendritic cells, mast cells, and B cells. Moreover, we discuss in vivo studies utilizing a variety of animal models of preeclampsia to further support the role of immune cells in this disease. Finally, we highlight the existing gaps in knowledge of the immunobiology of preeclampsia that require further investigation. The goal of this review is to promote translational research leading to clinically relevant strategies that can improve adverse perinatal outcomes resulting from the obstetrical syndrome of preeclampsia.

Differential iNKT and T Cells Activation in Non-Alcoholic Fatty Liver Disease and Drug-Induced Liver Injury

Background: Non-alcoholic fatty liver disease (NAFLD) and idiosyncratic drug-induced liver injury (DILI) could share molecular mechanisms involving the immune system. We aimed to identify activation immunological biomarkers in invariant natural killer T (iNKT) and CD4/CD8+ T cells in NAFLD and DILI. Methods: We analyzed the activation profile (CD69, CD25, and HLA-DR) and natural killer group 2 member D (NKG2D) on iNKT cells, and CD4/CD8 T cells in peripheral blood mononuclear cells from NAFLD, with or without significant liver fibrosis, and DILI patients. Results: There was an increase in iNKT cells in NAFLD patients compared to DILI or control subjects. Regarding the cellular activation profile, NAFLD with significant liver fibrosis (F ≥ 2) displayed higher levels of CD69+iNKT cells compared to NAFLD with none or mild liver fibrosis (F ≤ 1) and control patients. CD69+iNKT positively correlated with insulin resistance, aspartate aminotransferase (AST) level, liver fibrosis-4 index (FIB4) and AST to Platelet Ratio Index (APRI). DILI patients showed an increase in CD69+ and HLA-DR+ in both CD4+ and CD8+ T cells, detecting the most relevant difference in the case of CD69+CD8+ T cells. Conclusions: CD69+iNKT may be a biomarker to assess liver fibrosis progression in NAFLD. CD69+CD8+ T cells were identified as a potential distinctive biomarker for distinguishing DILI from NAFLD.

The CTRP3-AdipoR2 Axis Regulates the Development of Experimental Autoimmune Encephalomyelitis by Suppressing Th17 Cell Differentiation

C1q/TNF-related proteins (CTRP) including CTRP3 are a group of secreted proteins which have a complement C1q-like domain in common, and play versatile roles in lipid metabolism, inflammation, tumor metastasis and bone metabolism. Previously, we showed that the expression of C1qtnf3, encoding CTRP3, is highly augmented in joints of autoimmune arthritis models and CTRP3-deficiency exacerbates collagen-induced arthritis in mice. However, the mechanisms how CTRP3-deficiency exacerbates arthritis still remain to be elucidated. In this study, we showed that CTRP3 was highly expressed in Th17 cell, a key player for the development of autoimmune diseases, and Th17 cell differentiation was augmented in C1qtnf3^–/– mice. Th17 cell differentiation, but not Th1 cell differentiation, was suppressed by CTRP3 and this suppression was abolished by the treatment with a receptor antagonist against AdipoR2, but not AdipoR1, associated with suppression of Rorc and Stat3 expression. Furthermore, AdipoR1 and AdipoR2 agonist, AdipoRon suppressed Th17 cell differentiation via AdipoR2, but not AdipoR1. The development of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis was enhanced in C1qtnf3^–/– mice associated with increase of Th17 cell population. CTRP3 inhibited MOG-induced IL-17 production from T cells by affecting both T cells and dendritic cells. These results show that CTRP3 is an endogenous regulator of Th17 differentiation, suggesting that the CTRP3-AdipoR2 axis is a good target for the treatment of Th17 cell-mediated diseases.

Poly(I:C)-Induced Mesenchymal Stem Cells Protect the Kidney Against Ischemia/Reperfusion Injury via the TLR3/PI3K Pathway

Objective: To investigate the effect and protective mechanism of mesenchymal stem cell subpopulations on acute kidney injury by establishing a mouse model of renal ischemia-reperfusion injury.

Methods: Male C57BL/6 mice were randomly divided into five groups, namely, sham-operation group and those treated with normal saline, untreated mesenchymal stem cells, mesenchymal stem cells treated with lipopolysaccharide (LPS, pro-inflammatory phenotype) and mesenchymal stem cells treated with polyinosinic-polycytidylic acid (poly[I:C], anti-inflammatory phenotype) respectively. The renal function, histopathological damage, circulating inflammation levels and antioxidant capacity of mice were evaluated. The PI3 kinase p85 (PI3K) inhibitor was added into the conventional mesenchymal stem cell cultures in vitro to observe its effects on the secretion of anti-inflammatory cytokines.

Results: Mesenchymal stem cells treated with poly(I:C) (anti-inflammatory phenotype) could effectively reduce serum creatinine and blood urea nitrogen, attenuate histopathological damage and apoptosis level, decrease the level of circulating pro-inflammatory cytokines and increase the level of circulating anti-inflammatory cytokines, enhance peroxidase activity and reduce malondialdehyde content at each time point. After the addition of the PI3K inhibitor, the mRNA expression and protein secretion of indoleamine 2,3-dioxygenase 1 and heme oxygenase 1 of various mesenchymal stem cells were significantly reduced, and that of mesenchymal stem cells treated with poly(I:C) (anti-inflammatory phenotype) was more obvious.

Conclusions: Polyriboinosinic-polyribocytidylic acid (poly[I:C]), a synthetic double-stranded RNA, whose pretreatment induces mesenchymal stem cells to differentiate into the anti-inflammatory phenotype. Anti-inflammatory mesenchymal stem cells induced by poly(I:C) can better protect renal function, alleviate tissue damage, reduce circulating inflammation levels and enhance antioxidant capacity, and achieve stronger anti-inflammatory effects through the TLR3/PI3K pathway.

The Blockade of Interleukin-2 During the Acute Phase of Trypanosoma cruzi Infection Reveals Its Dominant Regulatory Role

Trypanosoma cruzi infection causes Chagas’ disease in humans. The infection activates the innate and adaptative immunity in an orchestrated immune response to control parasite growth, guaranteeing host survival. Despite an effective immune response to the parasite in the acute phase, the infection progresses to a chronic stage. The parasite infects different tissues such as peripheral neurons, the brain, skeletal muscle, and heart muscle, among many others. It is evident now that tissue-specific immune responses may develop along with anti-parasite immunity. Therefore, mechanisms to regulate immunity and to ensure tissue-specific tolerance are operating during the infection. Studying those immunoregulatory mechanisms is fundamental to improve host protection or control inflammatory reactions that may lead to pathology. The role of IL-2 during T. cruzi infection is not established. IL-2 production by T cells is strongly down-modulated early in the disease by unknown mechanisms and remains low during the chronic phase of the disease. IL-2 activates NK cells, CD4, and CD8 T cells and may be necessary to immunity development. Also, the expansion and maintenance of regulatory T cells require IL-2. Thus, IL-2 may be a key cytokine involved in promoting or down-regulating immune responses, probably in a dose-dependent manner. This study blocked IL-2 during the acute T. cruzi infection by using a neutralizing monoclonal antibody. The results show that parasitemia and mortality rate was lower in animals treated with anti-IL-2. The percentages and total numbers of CD4⁺CD25⁺Foxp3⁺ T cells diminished within three weeks of infection. The numbers of splenic activated/memory CD4 and CD8 splenic T cells increased during the acute infection. T cells producing IFN-γ, TNF-α and IL-10 also augmented in anti-IL-2-treated infected mice. The IL-2 blockade also increased the numbers of inflammatory cells in the heart and skeletal muscles and the amount of IL-17 produced by heart T cells. These results suggest that IL-2 might be involved in the immune regulatory response during the acute T. cruzi infection, dampening T cell activation through the expansion/maintenance of regulatory T cells and regulating IL-17 production. Therefore, the IL-2 pathway is an attractive target for therapeutic purposes in acute and chronic phases of Chagas’ disease.

Synergistic and additive interactions between receptor signaling networks drive the regulatory T cell versus T helper 17 cell fate choice

CD4+ T cells differentiate into subsets that promote immunity or minimize damage to the host. T helper 17 cells (Th17) are effector cells that function in inflammatory responses. T regulatory cells (Tregs) maintain tolerance and prevent autoimmunity by secreting immunosuppressive cytokines and expressing check point receptors. While the functions of Th17 and Treg cells are different, both cell fate trajectories require T cell receptor (TCR) and TGF-β receptor (TGF-βR) signals, and Th17 polarization requires an additional IL-6 receptor (IL-6R) signal. Utilizing high-resolution phosphoproteomics, we identified that both synergistic and additive interactions between TCR, TGF-βR, and IL-6R shape kinase signaling networks to differentially regulate key pathways during the early phase of Treg versus Th17 induction. Quantitative biochemical analysis revealed that CD4+ T cells integrate receptor signals via SMAD3, which is a mediator of TGF-βR signaling. Treg induction potentiates the formation of the canonical SMAD3/4 trimer to activate a negative feedback loop through kinases PKA and CSK to suppress TCR signaling, phosphatidylinositol metabolism, and mTOR signaling. IL-6R signaling activates STAT3 to bind SMAD3 and block formation of the SMAD3/4 trimer during the early phase of Th17 induction, which leads to elevated TCR and PI3K signaling. These data provide a biochemical mechanism by which CD4+ T cells integrate TCR, TGF-β, and IL-6 signals via generation of alternate SMAD3 complexes that control the development of early signaling networks to potentiate the choice of Treg versus Th17 cell fate.

The role and research progress of the balance and interaction between regulatory T cells and other immune cells in obesity with insulin resistance

Metabolic homoeostasis in adipose tissue plays a major role in obesity-related insulin resistance (IR). Regulatory T (Treg) cells have been recorded to regulate metabolic homoeostasis in adipose tissue. However, their specific mechanism is not yet known. This review aims to present the role of Treg cells and other immune cells in obesity-associated IR, focusing on the balance of numbers and functions of Treg cells and other immune cells as well as the crucial role of their interactions in maintaining adipose tissue homoeostasis. Th1 cells, Th17 cells, CD8⁺ T cells, and pro-inflammatory macrophages mediate the occurrence of obesity and IR by antagonizing Treg cells, while anti-inflammatory dendritic cells, eosinophils and type 2 innate lymphoid cells (ILC2s) regulate the metabolic homoeostasis of adipose tissue by promoting the proliferation and differentiation of Treg cells. γ δ T cells and invariant natural killer T (iNKT) cells have complex effects on Treg cells, and their roles in obesity-associated IR are controversial. The balance of Treg cells and other immune cells can help maintain the metabolic homoeostasis of adipose tissue. Further research needs to explore more specific molecular mechanisms, thus providing more precise directions for the treatment of obesity with IR.

Immunosuppressive activity of a cycloartane triterpene glycoside from Beesia calthaefolia by inhibiting T cell proliferation

BC-1 is a cycloartane triterpene glycoside isolated from the whole plant of Beesia calthaefolia. Our recent studies proved that BC-1 inhibited proliferation of splenic lymphocyte and phagocytosis of macrophages, and inhibited the increased production of TNF-α and IL-1β. However, it lacks of study about the immunomodulatory effect of BC-1 on purified T lymphocytes. Therefore, in the present study, we evaluated the suppressive potentials of BC-1 on immune responses in vitro. BC-1 markedly suppressed anti-CD3/CD28 mAbs (mAbs) induced murine T lymphocytes proliferation, the expression levels of CD69 and CD25 of CD3⁺ T cells. BC-1 could strongly decrease ratio of CD4⁺/CD8⁺, decrease the Th1/Th2 cytokines production (IL-2, IFN-γ, IL-4, and IL-10) of CD4⁺ T-cells. In addition, we studied signal transduction pathways about T-cell activation on puried murine CD4⁺ T lymphocytes by western-blot assay. The data revealed that BC-1 could inhibit the activation of JNK, ERK and PI3K/AKT signal transduction pathways. These results indicated that BC-1 possesses potential downregulating effect on the immune system and might be developed as an immunosuppressive agent in treatment of CD4⁺ T cell-mediated inflammatory and undesired immune responses.

Brazilian passion fruit as a new healthy food: from its composition to health properties and mechanisms of action

The Brazilian biodiversity is one of the largest in the world, with about 41 000 species cataloged within two global biodiversity hotspots: Atlantic Forest and Cerrado, the Brazilian savannah. Passiflora, known also as passion flowers, is a genus of which 96% of its species are distributed in the Americas, mainly Brazil and Colombia. Passion fruit extracts have a commercial value on a global scale through the pharmaceutical, nutraceutical, self-care, and food and beverage industries. Passiflora are widely studied due to their potential antioxidant, anti-inflammatory, anxiolytic, antidepressant and vascular and neuronal protective effects, probably owing to their content of polyphenols. Passiflora setacea DC is a species of wild passion fruit from the Brazilian Cerrado, rich in flavonoid C-glycosides, homoorientin, vitexin, isovitexin and orientin. Intake of these plant food bioactives has been associated with protection against chronic non-communicable diseases (CNDCs), including cardiovascular diseases, cancers, and neurodegenerative diseases. In this review, we aimed to discuss the varieties of Passiflora, their content in plant food bioactives and their potential molecular mechanisms of action in preventing or reversing CNDCs.

Hydrogen-Rich Water Improves Cognitive Ability and Induces Antioxidative, Antiapoptotic, and Anti-Inflammatory Effects in an Acute Ischemia-Reperfusion Injury Mouse Model

Background

Cerebral ischemia and its reperfusion injury facilitate serious neurodegenerative diseases such as dementia due to cell death; however, there is currently no treatment for it. Reactive oxygen species is one of the many factors that induce and worsen the development of such diseases, and it can be targeted by hydrogen treatment. This study examined the effect of molecular hydrogen in cerebral ischemia-reperfusion injury, which is emerging as a novel therapeutic agent for various diseases.

Methods

Ischemia-reperfusion injury was generated through bilateral common carotid artery occlusion in C57BL/6 mice. The test group received hydrogen-rich water orally during the test period. To confirm model establishment and the effect of hydrogen treatment, behavioural tests, biochemical assays, immunofluorescence microscopy, and cytokine assays were conducted.

Results

Open field and novel object recognition tests revealed that the hydrogen-treated group had improved cognitive function and anxiety levels compared to the nontreated group, while hematoxylin and eosin stain showed abundant pyknotic cells in a model mouse brain, and this was attenuated in the hydrogen-treated mouse brain. Total antioxidant capacity and thiobarbituric acid reactive substance assays revealed that hydrogen treatment induced antioxidative effects in the mouse brain. Immunofluorescence microscopy revealed attenuated apoptosis in the striatum, cerebral cortex, and hippocampus of hydrogen-treated mice. Western blotting showed that hydrogen treatment reduced Bax and TNFα levels. Finally, cytokine assays showed that IL-2 and IL-10 levels significantly differed between the hydrogen-treated and nontreated groups.

Conclusion

Hydrogen treatment could potentially be a future therapeutic strategy for ischemia and its derived neurodegenerative diseases by improving cognitive abilities and inducing antioxidative and antiapoptotic effects. Hydrogen treatment also decreased Bax and TNFα levels and induced an anti-inflammatory response via regulation of IL-2 and IL-10. These results will serve as a milestone for future studies intended to reveal the mechanism of action of molecular hydrogen in neurodegenerative diseases.

Interleukin-2 and regulatory T cells in rheumatic diseases

Failure of regulatory T (T_reg) cells to properly control immune responses leads invariably to autoimmunity and organ damage. Decreased numbers or impaired function of T_reg cells, especially in the context of inflammation, has been documented in many human autoimmune diseases. Restoration of T_reg cell fitness and/or expansion of their numbers using low-dose natural IL-2, the main cytokine driving T_reg cell survival and function, has demonstrated clinical efficacy in early clinical trials. Genetically modified IL-2 with an extended half-life and increased selectivity for T_reg cells is now in clinical development. Administration of IL-2 combined with therapies targeting other pathways involved in the expression of autoimmune diseases should further enhance its therapeutic potential. Ongoing clinical efforts that capitalize on the early clinical success of IL-2 treatment should bring the use of this cytokine to the forefront of biological treatments for autoimmune diseases.

Tetrahedral Framework Nucleic Acids Reverse New-Onset Type 1 Diabetes

Type 1 diabetes (T1D) is caused by breakdowns of central and peripheral immune tolerance and destructions of insulin-producing β-cells. Conventional insulin injection cannot cure the disease. Regulatory immune cells, including regulatory T-cells (Tregs) and regulatory B-cells (Bregs), play critical roles in immune tolerance. Inducing regulatory immune cells to halt the progress of T1D and restore immune tolerance is the promising approach in T1D immunotherapy. Here, tetrahedral framework nucleic acids (tFNAs) were utilized to treat T1D in non-obese diabetic (NOD) mice. 250 nM tFNA treatment was adopted in the experiment to reverse hyperglycemia and protect insulin-secreting β-cells in diabetic NOD mice. In addition, 250 nM tFNA treatment could induce Tregs and Bregs and suppress helper T (Th)-cells in the pancreas. In the pancreas, cytokines, as a significant signal during CD4⁺ T-cell differentiation, directly direct the differentiation programs. Apart from cytokines directing the differentiation of T-cells, the signal transducer and activator of transcription (STAT) signal is strongly associated with T-cell differentiation and T1D progression. We demonstrated tFNA treatment inducing regulatory immune cells probably by increasing TGF-β levels and the STAT signal. To sum up, 250 nM tFNA treatment could protect the diabetic NOD mice from hyperglycemia and preserve the functions of β-cells by restoring peripheral immune tolerance. The possible mechanism of inducing immune tolerance was related to the STAT signal and cytokine changes in the pancreas. Moreover, immunoregulation capabilities of tFNAs were demonstrated in the experiment, which set the foundation of tFNAs participating in further antigen-specific immunotherapies.

Arkadia-SKI/SnoN signaling differentially regulates TGF-β-induced iTreg and Th17 cell differentiation

TGF-β signaling is fundamental for both Th17 and regulatory T (Treg) cell differentiation. However, these cells differ in requirements for downstream signaling components, such as SMAD effectors. To further characterize mechanisms that distinguish TGF-β signaling requirements for Th17 and Treg cell differentiation, we investigated the role of Arkadia (RNF111), an E3 ubiquitin ligase that mediates TGF-β signaling during development. Inactivation of Arkadia in CD4⁺ T cells resulted in impaired Treg cell differentiation in vitro and loss of RORγt⁺FOXP3⁺ iTreg cells in the intestinal lamina propria, which increased susceptibility to microbiota-induced mucosal inflammation. In contrast, Arkadia was dispensable for Th17 cell responses. Furthermore, genetic ablation of two Arkadia substrates, the transcriptional corepressors SKI and SnoN, rescued Arkadia-deficient iTreg cell differentiation both in vitro and in vivo. These results reveal distinct TGF-β signaling modules governing Th17 and iTreg cell differentiation programs that could be targeted to selectively modulate T cell functions.

Human Wharton's Jelly-Derived Mesenchymal Stromal Cells Primed by Tumor Necrosis Factor-α and Interferon-γ Modulate the Innate and Adaptive Immune Cells of Type 1 Diabetic Patients

The unique immunomodulation and immunosuppressive potential of Wharton’s jelly-derived mesenchymal stromal cells (WJ-MSCs) make them a promising therapeutic approach for autoimmune diseases including type 1 diabetes (T1D). The immunomodulatory effect of MSCs is exerted either by cell-cell contact or by secretome secretion. Cell-cell contact is a critical mechanism by which MSCs regulate immune-responses and generate immune regulatory cells such as tolerogenic dendritic cells (tolDCs) and regulatory T cell (Tregs). In this study, we primed WJ-MSCs with TNF-α and IFN-γ and investigated the immunomodulatory properties of primed WJ-MSCs on mature dendritic cells (mDCs) and activated T cells differentiated from mononuclear cells (MNCs) of T1D patient’s. Our findings revealed that primed WJ-MSCs impaired the antigen-mediated immunity, upregulated immune-tolerance genes and downregulated immune-response genes. We also found an increase in the production of anti-inflammatory cytokines and suppression of the production of pro-inflammatory cytokines. Significant upregulation of FOXP3, IL10 and TGFB1 augmented an immunosuppressive effect on adaptive T cell immunity which represented a strong evidence in support of the formation of Tregs. Furthermore, upregulation of many critical genes involved in the immune-tolerance mechanism (IDO1 and PTGES2/PTGS) was detected. Interestingly, upregulation of ENTPD1/NT5E genes express a strong evidence to switch immunostimulatory response toward immunoregulatory response. We conclude that WJ-MSCs primed by TNF-α and IFN-γ may represent a promising tool to treat the autoimmune disorders and can provide a new evidence to consider MSCs- based therapeutic approach for the treatment of TID.

Iron deprivation restrains the differentiation and pathogenicity of T helper 17 cell

Iron plays a critical role in immune responses. However, its role in T helper cell differentiation and function remains poorly understood. In this study, it is shown that the restraint of iron availability through blocking CD71-mediated iron endocytosis impaired the differentiation and pathogenicity of T_H 17 cells. Administrations of anti-CD71 mAb could relieve the development of experimental autoimmune encephalomyelitis (EAE). Mechanistically, the iron deficiency due to the blocking of CD71 enhanced IL-2 expression, which further restrained the differentiation of T_H 17 cells. Meanwhile, CD71 blockade impaired histone modifications of Il17 gene and reduced the recruitment of RORγt to Il17a locus. In sum, the findings reveal that iron plays a pivotal role in regulating T_H 17 cell differentiation and function in autoimmune diseases.

Low-dose IL-2 therapy invigorates CD8+ T cells for viral control in systemic lupus erythematosus

Autoimmune diseases are often treated by glucocorticoids and immunosuppressive drugs that could increase the risk for infection, which in turn deteriorate disease and cause mortality. Low-dose IL-2 (Ld-IL2) therapy emerges as a new treatment for a wide range of autoimmune diseases. To examine its influence on infection, we retrospectively studied 665 patients with systemic lupus erythematosus (SLE) including about one third receiving Ld-IL2 therapy, where Ld-IL2 therapy was found beneficial in reducing the incidence of infections. In line with this clinical observation, IL-2 treatment accelerated viral clearance in mice infected with influenza A virus or lymphocytic choriomeningitis virus (LCMV). Noticeably, despite enhancing anti-viral immunity in LCMV infection, IL-2 treatment exacerbated CD8+ T cell-mediated immunopathology. In summary, Ld-IL2 therapy reduced the risk of infections in SLE patients and enhanced the control of viral infection, but caution should be taken to avoid potential CD8+ T cell-mediated immunopathology.

Th17 Cells in Periodontitis and Its Regulation by A20

Periodontitis is a prevalent chronic disease that results in loss of periodontal ligament and bone resorption. Triggered by pathogens and prolonged inflammation, periodontitis is modulated by the immune system, especially pro-inflammatory cells, such as T helper (Th) 17 cells. Originated from CD4⁺ Th cells, Th17 cells play a central role for they drive and regulate periodontal inflammation. Cytokines secreted by Th17 cells are also major players in the pathogenesis of periodontitis. Given the importance of Th17 cells, modulators of Th17 cells are of great clinical potential and worth of discussion. This review aims to provide an overview of the current understanding of the effect of Th17 cells on periodontitis, as well as a brief discussion of current and potential therapies targeting Th17 cells. Lastly, we highlight this article by summarizing the causal relationship between A20 (encoded by TNFAIP3), an anti-inflammatory molecule, and Th17 cell differentiation.

Regulation of IL-17A-Producing Cells in Skin Inflammatory Disorders

This review focuses on the IL-17A family of cytokines produced by T lymphocytes and other immune cells and how they are involved in cutaneous pathogenic responses. It will also discuss cutaneous dysbiosis and FOXP3⁺ regulatory T cells in the context of inflammatory conditions linked to IL-17 responses in the skin. Specifically, it will review key literature on chronic mucocutaneous candidiasis and psoriasis.

Primary culture of immature, naïve mouse CD4+ T cells

Primary T-cell culture is an invaluable model for investigating mechanisms underlying T-cell differentiation and function in health and disease. However, different culture conditions are required for immature versus mature CD4⁺ T cells. Here, we provide an improved culture protocol for immature naïve mouse CD4⁺ T cells, including details for splenocyte isolation, naïve CD4⁺ T-cell purification and differentiation, and functional evaluation via flow cytometry. This protocol can also be applied for immature human CD4⁺ T cells. For complete details on the execution of this protocol, please refer to Wang et al. (2019).

Vaccine-driven lung TRM cells provide immunity against Klebsiella via fibroblast IL-17R signaling

[Figure: see text].

The Peripheral Immune System and Traumatic Brain Injury: Insight into the role of T-helper cells

Emerging evidence suggests that immune-inflammatory processes are key elements in the physiopathological events associated with traumatic brain injury (TBI). TBI is followed by T-cell-specific immunological changes involving several subsets of T-helper cells and the cytokines they produce; these processes can have opposite effects depending on the disease course and cytokine concentrations. Efforts are underway to identify the T-helper cells and cytokine profiles associated with prognosis. These predictors may eventually serve as effective treatment targets to decrease morbidity and mortality and to improve the management of TBI patients. Here, we review the immunological response to TBI, the possible molecular mechanisms of this response, and therapeutic strategies to address it.

Emerging Complexity in CD4+T Lineage Programming and Its Implications in Colorectal Cancer

The intestinal immune system has the difficult task of protecting a large environmentally exposed single layer of epithelium from pathogens without allowing inappropriate inflammatory responses. Unmitigated inflammation drives multiple pathologies, including the development of colorectal cancer. CD4⁺T cells mediate both the suppression and promotion of intestinal inflammation. They comprise an array of phenotypically and functionally distinct subsets tailored to a specific inflammatory context. This diversity of form and function is relevant to a broad array of pathologic and physiologic processes. The heterogeneity underlying both effector and regulatory T helper cell responses to colorectal cancer, and its impact on disease progression, is reviewed herein. Importantly, T cell responses are dynamic; they exhibit both quantitative and qualitative changes as the inflammatory context shifts. Recent evidence outlines the role of CD4⁺T cells in colorectal cancer responses and suggests possible mechanisms driving qualitative alterations in anti-cancer immune responses. The heterogeneity of T cells in colorectal cancer, as well as the manner and mechanism by which they change, offer an abundance of opportunities for more specific, and likely effective, interventional strategies.

Clean up by aisle 2: roles for IL-2 receptors in host defense and tolerance

Although IL-2 was first recognized as growth factor for T cells, it is now also appreciated to be a key regulator of T cells through its effects on regulatory T cells (Treg). The IL-2 receptor (IL-2R) subunits' different (i) ligand affinities, (ii) dimerization or trimerization relationships with other cytokine subunits, (iii) expression across multiple cell types, and (iv) downstream signaling effects, largely dictate cellular tolerance and antimicrobial processes. Defects in IL-2Rγ result in profound and almost universally fatal immune deficiency, unless treated with hematopoietic stem cell transplantation (HSCT). Defects in IL-2Rα and IL-2Rβ result in more limited infection susceptibility, particularly to herpesviruses. However, the most prominent clinical symptomatology for IL-2Rα and IL-2Rβ defects include multi-organ autoimmunity and inflammation, consistent with the critical role of IL-2 in establishing and maintaining immune tolerance. Here, we review how we have arrived at our current understanding of the complex roles of IL-2/2R in host defense and tolerance focusing on the insights gained from human clinical immunology.

Clinical translation of immunomodulatory therapeutics

Immunomodulatory therapeutics represent a unique class of drug products that have tremendous potential to rebalance malfunctioning immune systems and are quickly becoming one of the fastest-growing areas in the pharmaceutical industry. For these drugs to become mainstream medicines, they must provide greater therapeutic benefit than the currently used treatments without causing severe toxicities. Immunomodulators, cell-based therapies, antibodies, and viral therapies have all achieved varying amounts of success in the treatment of cancers and/or autoimmune diseases. However, many challenges related to precision dosing, off-target effects, and manufacturing hurdles will need to be addressed before we see widespread adoption of these therapies in the clinic. This review provides a perspective on the progress of immunostimulatory and immunosuppressive therapies to date and discusses the opportunities and challenges for clinical translation of the next generation of immunomodulatory therapeutics.

Lack of NFATc1 SUMOylation prevents autoimmunity and alloreactivity

Posttranslational modification with SUMO is known to regulate the activity of transcription factors, but how SUMOylation of individual proteins might influence immunity is largely unexplored. The NFAT transcription factors play an essential role in antigen receptor-mediated gene regulation. SUMOylation of NFATc1 represses IL-2 in vitro, but its role in T cell-mediated immune responses in vivo is unclear. To this end, we generated a novel transgenic mouse in which SUMO modification of NFATc1 is prevented. Avoidance of NFATc1 SUMOylation ameliorated experimental autoimmune encephalomyelitis as well as graft-versus-host disease. Elevated IL-2 production in T cells promoted T reg expansion and suppressed autoreactive or alloreactive immune responses. Mechanistically, increased IL-2 secretion counteracted IL-17 and IFN-γ expression through STAT5 and Blimp-1 induction. Then, Blimp-1 repressed IL-2 itself, as well as the induced, proliferation-associated survival factor Bcl2A1. Collectively, these data demonstrate that prevention of NFATc1 SUMOylation fine-tunes T cell responses toward lasting tolerance. Thus, targeting NFATc1 SUMOylation presents a novel and promising strategy to treat T cell-mediated inflammatory diseases.

Retinoic Acid Induces Functionally Suppressive Foxp3+RORγt+ T Cells In Vitro

Introduction

CD4⁺ T cells with regulatory function co-expressing Foxp3 and RORγt are linked to the development of oral tolerance towards innocuous food antigens in mice. This study aimed to discern the role played by IL-6 and retinoic acid (RA) in the in vitro generation of Foxp3⁺RORγt⁺ T cells and to investigate whether such cells have suppressive properties.

Methods

CD4⁺CD25^- T cells isolated from the spleen of BALB/c mice, were stimulated in the presence of IL-2 alone or together with TFG-β and different concentrations of IL-6 and/or RA. Percentage of Foxp3⁺, RORγt⁺, IL-17⁺, Foxp3⁺RORγt^-, Foxp3⁺RORγt⁺, and Foxp3^-RORγt⁺ T cells within the total CD4⁺ T cell population, production of cytokines (IL-10 and IL-17A) and gene expression (Foxp3, Rorc, Tgfb1, Il6, Il10, and Il17) were assessed at different time points. The phenotype and ability of cells generated from CD4⁺CD44^-CD62L⁺ cells in the presence of RA to suppress effector T cell proliferation was assessed.

Results

TGF-β plus IL-6 induced the generation of Foxp3⁺ and double positive Foxp3⁺RORγt⁺ T cells to a higher extent than TGF-β alone at the beginning of the incubation period, although expression of Foxp3 subsequently declined. RA, added to TGF-β, increased Foxp3 and Rorc expression and Foxp3 and RORγt transcription and promoted the differentiation of Foxp3⁺RORγt^- and Foxp3⁺RORγt⁺ cells that expressed and secreted IL-17. Foxp3⁺ T cells generated in vitro in presence of RA were functionally suppressive.

Conclusions

Under the influence of IL-2 and TGF-β, suppressive Foxp3⁺RORγt⁺ T cells that express and secrete IL-17 can be produced in vitro and RA further contributes to stabilize this phenotype.

Transcriptional and posttranslational regulation of Th17/Treg balance in health and disease

Regulatory T (Treg) cells and T helper type 17 (Th17) cells play important roles in adaptive immune responses, antagonizing each other in immune disorders. Th17/Treg balance is critical to maintaining the immune homeostasis of human bodies and is tightly regulated under healthy conditions. The transcription factors that are required for driving Th17 and Treg cell lineages differentiation respectively, RORγt and FOXP3 are tightly regulated under different tissue microenvironment, especially the transcriptional induction, posttranslational modifications, and dynamic enzymatic cofactors binding. The imbalance caused by alteration of the quantity or properties of RORγt⁺ Th17 or FOXP3⁺ Treg can contribute to inflammatory disorders in humans. Restoring Th17/Treg balance by modifying the enzymatic activities of RORγt and FOXP3 binding partners may be therapeutically applied to treat severe immune disorders. In this review, we focus on the transcriptional and posttranslational regulations of Th17/Treg balance, immune disorders caused by Th17/Treg imbalance, and new therapeutic strategies for restoring immune homeostasis.

Interactions Between Specific Immune Status of Pregnant Women and SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the Coronavirus Disease 2019 (COVID-19) global pandemic. Because it is a new and highly contagious coronavirus, most people, especially pregnant women, lack immunity. It is therefore important to understand the interaction between why pregnant women are susceptible to SARS-CoV-2 and the specific immune systems of pregnant women. Here, we provide an overview of the changes that occur in the immune system during pregnancy, the activation and response of the immune system in pregnant women with COVID-19, adverse pregnancy outcomes in pregnant women with COVID-19, and the treatment and prevention of COVID-19 in this population.

STAT5 Represses a STAT3-Independent Th17-like Program during Th9 Cell Differentiation

IL-9-producing Th cells, termed Th9 cells, contribute to immunity against parasites and cancers but have detrimental roles in allergic disease and colitis. Th9 cells differentiate in response to IL-4 and TGF-β, but these signals are insufficient to drive Th9 differentiation in the absence of IL-2. IL-2-induced STAT5 activation is required for chromatin accessibility within Il9 enhancer and promoter regions and directly transactivates the Il9 locus. STAT5 also suppresses gene expression during Th9 cell development, but these roles are less well defined. In this study, we demonstrate that human allergy-associated Th9 cells exhibited a signature of STAT5-mediated gene repression that is associated with the silencing of a Th17-like transcriptional signature. In murine Th9 cell differentiation, blockade of IL-2/STAT5 signaling induced the expression of IL-17 and the Th17-associated transcription factor Rorγt. However, IL-2-deprived Th9 cells did not exhibit a significant Th17- or STAT3-associated transcriptional signature. Consistent with these observations, differentiation of IL-17-producing cells under these conditions was STAT3-independent but did require Rorγt and BATF. Furthermore, ectopic expression of Rorγt and BATF partially rescued IL-17 production in STAT3-deficient Th17 cells, highlighting the importance of these factors in this process. Although STAT3 was not required for the differentiation of IL-17-producing cells under IL-2-deprived Th9 conditions, their prolonged survival was STAT3-dependent, potentially explaining why STAT3-independent IL-17 production is not commonly observed in vivo. Together, our data suggest that IL-2/STAT5 signaling plays an important role in controlling the balance of a Th9 versus a Th17-like differentiation program in vitro and in allergic disease.

HuR Plays a Positive Role to Strengthen the Signaling Pathways of CD4+ T Cell Activation and Th17 Cell Differentiation

After antigen and/or different cytokine stimulation, CD4⁺ T cells activated and differentiated into distinct T helper (Th) cells via differential T cell signaling pathways. Transcriptional regulation of the activation and differentiation of naïve CD4⁺ T cells into distinct lineage Th cells such as Th17 cells has been fully studied. However, the role of RNA-binding protein HuR in the signaling pathways of their activation and differentiation has not been well characterized. Here, we used HuR conditional knockout (HuR KO) CD4⁺ T cells to study mechanisms underlying HuR regulation of T cell activation and differentiation through distinct signaling pathways. Our work showed that, mechanistically, HuR positively promoted CD3g expression by binding its mRNA and enhanced the expression of downstream adaptor Zap70 and Malt1 in activated CD4⁺ T cells. Compared to WT Th0 cells, HuR KO Th0 cells with reduced Bcl-2 expression are much more susceptible to apoptosis than WT Th0 cells. We also found that HuR stabilized IL-6Rα mRNA and promoted IL-6Rα protein expression, thereby upregulating its downstream phosphorylation of Jak1 and Stat3 and increased level of phosphorylation of IκBα to facilitate Th17 cell differentiation. However, knockout of HuR increased IL-22 production in Th17 cells, which was due to HuR deficiency in reducing IL-22 transcription repressor c-Maf expression. These results highlight the importance of HuR in TCR signaling and IL-6/IL-6R axis driving naïve CD4⁺ T cell activation and differentiation into Th17 cells.

Molecular biochemical aspects of salt (sodium chloride) in inflammation and immune response with reference to hypertension and type 2 diabetes mellitus

Obesity, insulin resistance, type 2 diabetes mellitus (T2DM) and hypertension (HTN) are common that are associated with low-grade systemic inflammation. Diet, genetic factors, inflammation, and immunocytes and their cytokines play a role in their pathobiology. But the exact role of sodium, potassium, magnesium and other minerals, trace elements and vitamins in the pathogenesis of HTN and T2DM is not known. Recent studies showed that sodium and potassium can modulate oxidative stress, inflammation, alter the autonomic nervous system and induce dysfunction of the innate and adaptive immune responses in addition to their action on renin-angiotensin-aldosterone system. These actions of sodium, potassium and magnesium and other minerals, trace elements and vitamins are likely to be secondary to their action on pro-inflammatory cytokines IL-6, TNF-α and IL-17 and metabolism of essential fatty acids that may account for their involvement in the pathobiology of insulin resistance, T2DM, HTN and autoimmune diseases.