Decrease In Th17 Cells Research Articles

Impact of the adenosine receptor A2BR expressed on myeloid cells on immune regulation during pregnancy.

During pregnancy, the maternal immune system must carefully balance protection against pathogens with tolerance toward the semiallogeneic fetus. Dysfunctions of the immune system can lead to severe complications such as preeclampsia, fetal growth restriction, or pregnancy loss. Adenosine plays a role in physiological processes and plasma-level increase during pregnancy. The adenosine receptor A2B (A2BR), which is expressed on both, immune and nonimmune cells, is activated by high adenosine concentrations, achieved during pregnancy. We investigated the impact of A2BR expressed on myeloid cells on immune regulation during pregnancy using a mouse model with myeloid deficiency for A2BR. We demonstrate systemic changes in myeloid and lymphoid cell populations during pregnancy in A2BR-KO (Adora2B923f/f-LysMCre) mice with increased monocytes, neutrophils, and T cells but decreased B cells as well as altered T-cell subpopulations with decreased Th1 cells and Tregs and increased Th17 cells. Lack of A2BR on myeloid cells caused an increased systemic expression of IL-6 but decreased systemic accumulation and function of MDSC and reduced numbers of uterine natural killer cells. The pregnancy outcome was only marginally affected. Our results demonstrate that A2BR on myeloid cells plays a role in immune regulation during pregnancy, but the clinical impact on pregnancy remains unclear.

The use of metagenomic and untargeted metabolomics in the analysis of the effects of the Lycium barbarum glycopeptide on allergic airway inflammation induced by Artemesia annua pollen

Ethnopharmacological relevanceThe prevalence of allergic airway inflammation (AAI) worldwide is high. Artemisia annua L. pollen is spread worldwide, and allergic diseases caused by its plant polysaccharides, which are closely related to the intestinal microbiota, have anti-inflammatory effects. Further isolation and purification of Lycium barbarum L. yielded its most effective component Lycium barbarum L. glycopeptide (LbGP), which can inhibit inflammation in animal models. However, its therapeutic effect on AAI and its mechanism of regulating the intestinal flora have not been fully investigated. Aim of the studyTo explore LbGP in APE-induced immunological mechanisms of AAI and the interaction mechanism of the intestinal flora and metabolites. MethodsA mouse model of AAI generated from Artemisia annua pollen was constructed, and immunological indices related to the disease were examined. A combination of macrogenomic and metabolomic analyses was used to investigate the effects of LbGP on the gut microbial and metabolite profiles of mice with airway inflammation. ResultsLbGP effectively alleviated Artemisia. annua pollen extract (APE)-induced AAI, corrected Th1/Th2 immune dysregulation, decreased Th17 cells, increased Treg cells, and altered the composition and function of the intestinal microbiota. LbGP treatment increased the number of OdoribacterandDuncaniella in the intestines of the mice, but the numble of Alistipes and Ruminococcus decreased. Metabolite pathway enrichment analysis were used to determine the effects of taurine and hypotaurine metabolism, bile acid secretion, and pyrimidine metabolism pathways on disease. ConclusionOur results revealed significant changes in the macrogenome and metabolome following APE and LbGP intervention, revealed potential correlations between gut microbial species and metabolites, and highlighted the beneficial effects of LbGP on AAI through the modulation of the gut microbiome and host metabolism.

Mesenteric lymph nodes: a critical site for the up-regulatory effect of hUC-MSCs on Treg cells by producing TGF-β1 in colitis treatment

BackgroundMesenchymal stem cells (MSCs) demonstrate a wide range of therapeutic capabilities in the treatment of inflammatory bowel disease (IBD). The intraperitoneal injection of MSCs has exhibited superior therapeutic efficacy on IBD than intravenous injection. Nevertheless, the precise in vivo distribution of MSCs and their biological consequences following intraperitoneal injection remain inadequately understood. Additional studies are required to explore the correlation between MSCs distribution and their biological effects.MethodsFirst, the distribution of human umbilical cord MSCs (hUC-MSCs) and the numbers of Treg and Th17 cells in mesenteric lymph nodes (MLNs) were analyzed after intraperitoneal injection of hUC-MSCs. Subsequently, the investigation focused on the levels of transforming growth factor beta1 (TGF-β1), a key cytokine to the biology of both Treg and Th17 cells, in tissues of mice with colitis, particularly in MLNs. The study also delved into the impact of hUC-MSCs therapy on Treg cell counts in MLNs, as well as the consequence of TGFB1 knockdown hUC-MSCs on the differentiation of Treg cells and the treatment of IBD.ResultsThe therapeutic effectiveness of intraperitoneally administered hUC-MSCs in the treatment of colitis was found to be significant, which was closely related to their quick migration to MLNs and secretion of TGF-β1. The abundance of hUC-MSCs in MLNs of colitis mice is much higher than that in other organs even the inflamed sites of colon. Intraperitoneal injection of hUC-MSCs led to a significant increase in the number of Treg cells and a decrease in Th17 cells especially in MLNs. Furthermore, the concentration of TGF-β1, the key cytokine for Treg differentiation, were also found to be significantly elevated in MLNs after hUC-MSCs treatment. Knockdown of TGFB1 in hUC-MSCs resulted in a noticeable reduction of Treg cells in MLNs and the eventually failure of hUC-MSCs therapy in colitis.ConclusionsMLNs may be a critical site for the regulatory effect of hUC-MSCs on Treg/Th17 cells and the therapeutic effect on colitis. TGF-β1 derived from hUC-MSCs promotes local Treg differentiation in MLNs. This study will provide new ideas for the development of MSC-based therapeutic strategies in IBD patients.

Peroxynitrite reduces Treg cell expansion and function by mediating IL-2R nitration and aggravates multiple sclerosis pathogenesis

T-helper 17 cells and regulatory T cells (Treg) are critical regulators in the pathogenesis of multiple sclerosis (MS) but the factors affecting Treg/Th17 balance remains largely unknown. Redox balance is crucial to maintaining immune homeostasis and reducing the severity of MS but the underlying mechanisms are unclear yet. Herein, we tested the hypothesis that peroxynitrite, a representative molecule of reactive nitrogen species (RNS), could inhibit peripheral Treg cells, disrupt Treg/Th17 balance and aggravate MS pathology by inducing nitration of interleukin-2 receptor (IL-2R) and down-regulating RAS/JNK-AP-1 signalling pathway. Experimental autoimmune encephalomyelitis (EAE) mouse model and serum samples of MS patients were used in the study. We found that the increases of 3-nitrotyrosine and IL-2R nitration in Treg cells were coincided with disease severity in the active EAE mice. Mechanistically, peroxynitrite-induced IL-2R nitration down-regulated RAS/JNK signalling pathway, subsequently impairing peripheral Treg expansion and function, increasing Teff infiltration into the central nerve system (CNS), aggravating demyelination and neurological deficits in the EAE mice. Those changes were abolished by peroxynitrite decomposition catalyst (PDC) treatment. Furthermore, transplantation of the PDC-treated-autologous Treg cells from donor EAE mice significantly decreased Th17 cells in both axillary lymph nodes and lumbar spinal cord, and ameliorated the neuropathology of the recipient EAE mice. Those results suggest that peroxynitrite could disrupt peripheral Treg/Th17 balance, and aggravate neuroinflammation and neurological deficit in active EAE/MS pathogenesis. The underlying mechanisms are related to induce the nitration of IL-2R and inhibit the RAS/JNK-AP-1 signalling pathway in Treg cells. The study highlights that targeting peroxynitrite-mediated peripheral IL-2R nitration in Treg cells could be a novel therapeutic strategy to restore Treg/Th17 balance and ameliorate MS/EAE pathogenesis. The study provides valuable insights into potential role of peripheral redox balance in maintaining CNS immune homeostasis.

Alterations in Peripheral Lymphocyte Subsets under Immunochemotherapy in Stage IV SCLC Patients: Th17 Cells as Potential Early Predictive Biomarker for Response.

UICC stage IV small-cell lung cancer (SCLC) is a highly aggressive malignancy without curative treatment options. Several randomized trials have demonstrated improved survival rates through the addition of checkpoint inhibitors to first-line platin-based chemotherapy. Consequently, a combination of chemo- and immunotherapy has become standard palliative treatment. However, no reliable predictive biomarkers for treatment response exist. Neither PD-L1 expression nor tumor mutational burden have proven to be effective predictive biomarkers. In this study, we compared the cellular immune statuses of SCLC patients to a healthy control cohort and investigated changes in peripheral blood B, T, and NK lymphocytes, as well as several of their respective subsets, during treatment with immunochemotherapy (ICT) using flow cytometry. Our findings revealed a significant decrease in B cells, while T cells showed a trend to increase throughout ICT. Notably, high levels of exhausted CD4+ and CD8+ cells, alongside NK subsets, increased significantly during treatment. Furthermore, we correlated decreases/increases in subsets after two cycles of ICT with survival. Specifically, a decrease in Th17 cells indicated a better overall survival. Based on these findings, we suggest conducting further investigation into Th17 cells as a potential early predictive biomarkers for response in patients receiving palliative ICT for stage IV SCLC.

Low-intensity pulsed ultrasound protects from inflammatory dilated cardiomyopathy through inciting extracellular vesicles.

CD4+ T cells are activated during inflammatory dilated cardiomyopathy (iDCM) development to induce immunogenic responses that damage the myocardium. Low-intensity pulsed ultrasound (LIPUS), a novel physiotherapy for cardiovascular diseases, has recently been shown to modulate inflammatory responses. However, its efficacy in iDCM remains unknown. Here, we investigated whether LIPUS could improve the severity of iDCM by orchestrating immune responses and explored its therapeutic mechanisms. In iDCM mice, LIPUS treatment reduced cardiac remodelling and dysfunction. Additionally, CD4+ T-cell inflammatory responses were suppressed. LIPUS increased Treg cells while decreasing Th17 cells. LIPUS mechanically stimulates endothelial cells, resulting in increased secretion of extracellular vesicles (EVs), which are taken up by CD4+ T cells and alter their differentiation and metabolic patterns. Moreover, EVs selectively loaded with microRNA (miR)-99a are responsible for the therapeutic effects of LIPUS. The hnRNPA2B1 translocation from the nucleus to the cytoplasm and binding to caveolin-1 and miR-99a confirmed the upstream mechanism of miR-99a transport. This complex is loaded into EVs and taken up by CD4+ T cells, which further suppress mTOR and TRIB2 expression to modulate cellular differentiation. Our findings revealed that LIPUS uses an EVs-dependent molecular mechanism to protect against iDCM progression. Therefore, LIPUS is a promising new treatment option for iDCM.

Pulsatilla saponin inhibits the proliferation of keratinocytes and ameliorates imiquimod-induced psoriasis through the NF-κB and STAT3 signaling pathways

Background and aimPulsatilla saponin (Ps) was isolated from Pulsatilla chinensis (Bunge) Regel, a traditional Chinese medicine, that has anti-proliferation, anti-inflammation, anti-tumor and immunomodulation activities. However, the anti-psoriasis activity of Ps and its underlying mechanisms have not been fully elucidated. This study aims to investigate the effect and potential mechanisms of Ps on psoriasis. Experimental procedurePs underwent quality control through HPLC and NMR analysis. Wound healing assay, MTT, clone assay, and EdU staining were used to detect HaCaT cells proliferation. Western blot and immunofluorescence were used to assess the expression of proteins. The th17 cells population was analyzed by flow cytometry. The levels of cytokines in the mice skin tissues were measured by RT-qPCR and ELISA. Results and conclusionIn vitro, Ps has an inhibition effect on the proliferation of M5-induced HaCaT cells. Ps inhibited proliferation by regulating NF-κB and JAK1/STAT3 pathways. Additionally, Ps decreased TNF-α, IL-1β, and IL-6 mRNA levels in M5-induced HaCaT cells. In vivo, Ps improved the pathological damage of Imiquimod (IMQ)-induced psoriasis BALB/c mice skin and reduced the Ki67 level in mice skin tissue. Further results showed that Ps decreased Th17 cells differentiation and IL-22, IL-17A, IL-6, IFN-γ, TNF-α, and IL-1β secretion. Ps could ameliorate the psoriatic symptoms, decrease M5-induced HaCaT cell proliferation, and decrease the differentiation of Th17 cells in IMQ-induced psoriasis mice. Ps suppressed the release of inflammation cytokines by regulating NF-κB and JAK1/STAT3 pathways. Those results indicate that Ps has promising therapeutic potential for psoriasis treatment.

P086 Identification of a Novel Immunometabolic Target and Agonist for PLXDC2 for Amelioration of DSS Colitis Model in Mice

Abstract Background PLXDC2 is expressed on the cell surface of macrophage, dendritic and specific mesenchymal and epithelial cells whose activation shifts cellular metabolism and reduces oxidative stress to rebalance the immune response and decrease inflammation. It’s role in IBD pathogenesis is unknown. PLXDC2 activation improves disease severity in rheumatoid arthritis models1, while loss of PLXDC2 exacerbates the severity of disease in DSS colitis2. PX-04 is a novel, first-in-class, orally active PLXDC2 agonist. Here, we report on the consequences of activating PLXDC2 using PX-04 in an acute DSS colitis model. Methods Mice were given DSS in drinking water for seven days to induce disruption of the epithelial layer. At project initiation, mice were 8 weeks of age and began once daily dosing with 20mg/kg of PX-04 24 hours after being placed on DSS. Mice were weighed and scored daily for 15 symptoms of disease (weight loss, diarrhea, rectal bleeding, rectal inflammation, pain, & overall behavior). Colons were collected and digested, and the resultant cellular suspensions were filtered to produce single cell suspensions. Colonic Lamina Propria Immune cells were isolated by Percoll gradient centrifugation. Cells were labeled with mixtures of extracellular (CD45, CD3, CD4, CD8, CD19, NK1.1, CD25, F4/80, CD11b, Gr1, CX3CR1, CD64) and intracellular (Tbet, RORγT, FOXP3, IFNγ, IL17, IL10, TNFα) antibodies in a sequential live staining in 96-well plates. Data was acquired using a FACS Celesta flow cytometer with FACSDiva software. Results Oral PX-04 treatment decreased the cumulative disease activity of mice challenged with DSS (FIG 1A). Immunologically, PX-04 affected both the adaptive and innate immune responses. First, PX-04 greatly decreased Th17 cells in the colon, while providing a slight increase to regulatory CD4+ T cells (FIG. 1C). A lower proportion of Natural Killer (NK) cells (FIG. 7D) produced IFNγ. Meanwhile, the proportion of TNF producing dendritic cells was decreased by PX-04 treatment. Conclusion Conclusion: PLXDC2 is expressed in cells relevant to IBD pathogenesis. PX-04, which binds to and activates PLXDC2, effectively decreases levels of effector T cells and myeloid cells, as well as overall disease severity in acute DSS colitis, warranting further investigation. 1Tubau-Juni et al. J Immunol 206(Supp) 2Tubau-Juni et al. Sci Rep 10(1)

Analysis of Peripheral Blood T Lymphocyte Subsets in Multiple Myeloma Patients.

The aim of this study was to investigate the changes of T lymphocyte subsets (Th1, Th2, Tc1, Tc2, and Th17) and memory T lymphocyte subsets (Tcm and Tem) in patients with multiple myeloma (MM) at different stages of the disease. In total, 25 newly diagnosed patients with MM were selected as the study subjects and 30 healthy people were selected as the control group. The subsets of T lymphocytes such as Th1, Th2, Tc1, Tc2, Th17, Tcm, and Tem in the peripheral blood were detected by flow cytometry at the time of initial diagnosis, infection, and remission. Th1, Tem, and Tcm cells in MM patients showed a significant decrease compared to the control group. Th2 and Th17 cells in MM patients showed a significant increase compared to the control group. Total Th1 cells and memory Th1 cells in MM patients with bacterial infection were significantly higher than at initial diagnosis (p < 0.05). The Tcm of Th2 cells in the remission stage were significantly higher than those in MM patients with no remission. MM patients have decreased Th1 cells and increased Th2 and Th17 cells. The changes in memory Th1 cells were related to bacterial infection in MM patients. The increase of Tcm of Th2 cells may be associated with disease remission. The balance of T lymphocyte subsets plays an important role in the pathogenic course of MM.

Gut microbial metabolite deoxycholic acid facilitates Th17 differentiation through modulating cholesterol biosynthesis and participates in high-fat diet-associated colonic inflammation

BackgroundHigh-fat diet (HFD) is closely associated with the increased prevalence of inflammatory bowel disease (IBD). Excessive gut microbial metabolite deoxycholic acid (DCA) caused by HFD plays significant roles in eliciting intestinal inflammation, however, the mechanism underlining the induction of inflammatory response by DCA has not been fully elucidated. The purpose of this study was to investigate the role of DCA in the triggering of inflammation via affecting CD4+ T cell differentiation.ResultsMurine CD4+T cells were cultured under Th1, Th2 or Th17-polarizing conditions treated with or without different dosage of DCA, and flowcytometry was conducted to detect the effect of DCA on CD4+ T cell differentiation. Alteration of gene expression in CD4+ T cells upon DCA treatment was determined by RNA-sequencing and qRT-PCR. Bioinformatic analysis, cholesterol metabolic profiling, ChIP assay and immuno-fluorescent staining were further applied to explore the DCA-regulated pathway that involved in CD4+T cell differentiation. The results showed that DCA could dose-dependently promote the differentiation of CD4+ T cell into Th17 linage with pathogenic signature. Mechanistically, DCA stimulated the expression of cholesterol biosynthetic enzymes CYP51 and led to the increased generation of endogenous RORγt agonists, including zymosterol and desmosterol, therefore facilitating Th17 differentiation. Up-regulation of CYP51 by DCA was largely mediated via targeting transcription factor SREBP2 and at least partially through bile acid receptor TGR5. In addition, DCA-supplemented diet significantly increased intestinal Th17 cell infiltration and exacerbated TNBS-induced colitis. Administration of cholestyramine to eliminate fecal bile acid obviously alleviated colonic inflammation accompanied by decreased Th17 cells in HFD-fed mice.ConclusionsOur data establish a link between DCA-induced cholesterol biosynthesis in immune cells and gut inflammation. Modulation of bile acid level or targeting cholesterol metabolic pathway may be potential therapeutic measurements for HFD-related colitis.

Icaritin attenuates recurrent spontaneous abortion in mice by modulating Treg/Th17 imbalance via TGF-β/SMAD signaling pathway

Recurrent spontaneous abortion (RSA) is a challenging global issue. Although the cause is unknown, increasing evidence suggests that immunological factors play a crucial role in RSA development. Icaritin (ICT), a natural compound derived from Epimedium, has demonstrated diverse biological activities, including anti-inflammatory, anti-cancer, and immunomodulatory effects. In this study, we aimed to investigate the potential therapeutic role of ICT in mitigating RSA in a mouse model. Specifically, we sought to determine whether ICT could modulate the Treg/Th17 cell imbalance via the TGF-β/SMAD signaling pathway and contributed to improved pregnancy outcomes. We conducted experiments on a mouse model with RSA and administered ICT orally. We then examined the effects of ICT on various types of immune cells including Treg and Th17 cells, and assessed the pregnancy outcomes. We also investigated the potential signaling pathway ICT exerted its effects. Our findings revealed that treatment with ICT led to an increase in Treg cells and a decrease in Th17 cells, which restored immune homeostasis and contributed to improved pregnancy outcomes. Furthermore, our data demonstrated that ICT's effects were mediated through the activation of TGF-β/SMAD signaling components. In conclusion, our study suggested that ICT ameliorated RSA by modulating Treg/Th17 cell imbalance via the TGF-β/SMAD signaling pathway. General significanceOur results highlighted the potential of ICT as a novel therapeutic agent for RSA, offering new insights into the underlying mechanisms and opening avenues for future research and clinical translation.

Serum JKAP reflects Th2 and Th17 cell levels, and diabetic nephropathy risk and severity in diabetes mellitus patients.

Objective: This studyaimed to explore the potency of serum JKAPfor estimating diabetic nephropathyrisk in diabetes mellitus (DM) patients. Methods: Serum JKAP was detected in 212 DM patients. According to urinary albumin-to-creatinine ratio, DM patients were divided into normoalbuminuria, microalbuminuriaand macroalbuminuria groups. Results: JKAP declined in themacroalbuminuria group versus normoalbuminuria group (p<0.001). In DM patients, JKAP inversely correlated with Th17 cells (p<0.001) but positively related to Th2 cells (p=0.003). After adjustment, JKAP independently estimated lower risks of albuminuria (microalbuminuria+macroalbuminuria; odds ratio=0.966, p<0.001) and macroalbuminuria (odds ratio=0.948; p=0.002). Conclusion: Serum JKAP reflects increased Th2 cells, decreased Th17 cells, andlower diabetic nephropathy risk and severity in DM patients.

Combining nano-curcumin with catechin improves COVID-19-infected patient's inflammatory conditions

AimsA hyperinflammatory condition is brought on by the development of Coronavirus disease 2019 (COVID-19), which is characterized by an elevation of T helper (Th) 17 cells, high levels of pro-inflammatory cytokines, and a depletion of regulatory T (Treg) cells. MethodsIn this research, we examined the effect of nano-curcumin and catechin on the TCD4+, TCD8+, Th17, and Treg cells and their associated factors in COVID-19 patients. For this purpose, 160 (50 patients excluded during the study) COVID-19 patients were divided into four groups: placebo, nano-curcumin, catechin, and nano-curcumin + catechin. The frequency of TCD4+, TCD8+, Th17, and Treg cells, the gene expression of transcription factors (STAT3, RORt, and FoxP3) relevant to Th17 and Treg, as well as the serum levels of cytokines (IL-6, IL17, IL1-b, IL-10, and TGF-), were all evaluated intra- and inter-group, before and after treatment, in all groups. ResultsOur study showed that TCD4 + and TCD8 + cells were significantly higher in the nano-curcumin + catechin group compared to the control group, whereas Th17 was lower than the initial value. Furthermore, compared to the placebo-received group, cytokines and transcription factors associated with Th17 were significantly lower in the nano-curcumin + catechin group. Additionally, combined therapy increased Treg cells and transcription factors compared to the placebo group. ConclusionOverall, our results show that combining nano-curcumin with catechin has a more notable impact on the enhancement of TCD4+, TCD8+, and Treg cells, as well as a decrease in Th17 cells and their mediators, suggesting a promising combination therapy in reducing the inflammatory conditions of COVID-19 infected patients.

Pterostilbene mediates glial and immune responses to alleviate chronic intermittent hypoxia-induced oxidative stress in nerve cells.

Chronic intermittent hypoxia (CIH) induces oxidative stress in the brain, causing sleep disorders. Herein, we investigated the role of pterostilbene (Pte) in CIH-mediated oxidative stress in the brain tissue. A CIH mouse model was constructed by alternately reducing and increasing oxygen concentration in a sealed box containing the mouse; brain tissue and serum were then collected after intragastric administration of Pte. Neurological function was evaluated through field experiments. The trajectory of the CIH mice to the central region initially decreased and then increased after Pte intervention. Pte increased the number of neuronal Nissl bodies in the hippocampus of CIH mice, upregulated the protein levels of Bcl-2, occludin, and ZO-1 as well as the mRNA and protein levels of cAMP-response element binding protein (CREB) and p-BDNF, and reduced the number of neuronal apoptotic cells, Bax protein levels, IBA-1, and GFAP levels. Simultaneously, Pte reversed the decreased levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and BDNF and increased levels of malondialdehyde (MDA) in the serum of CIH mice. Pte increased Th2 cells, Treg cells, IL-4, IL-10, and TGF-β1 levels and decreased Th1 cells, Th17 cells, IFN-γ, IL-6, and IL- 17A levels in activated BV2 cells and hippocampus in CIH mice. The protein levels of p-ERK1/2, TLR4, p-p38, p-p65, and Bax, apoptosis rate, MDA concentration, Bcl-2 protein level, cell viability, and SOD and GSH-PX concentrations decreased after the activation of BV2 cells. Pte inhibited gliocytes from activating T-cell immune imbalance through p-ERK signaling to alleviate oxidative stress injury in nerve cells.

Obstructive Sleep Apnea-Induced Hypertension Is Associated With Increased Gut and Neuroinflammation.

Background Obstructive sleep apnea (OSA) is an independent risk factor for the development of hypertension. We have demonstrated that OSA induces gut dysbiosis, and this dysbiotic microbiota contributes to hypertension. However, the mechanisms linking gut dysbiosis to blood pressure regulation remain unclear. Recent studies demonstrate that gut dysbiosis can induce a proinflammatory response of the host resulting in peripheral and neuroinflammation, key factors in the development of hypertension. We hypothesized that OSA induces inflammation in the gut that contributes to neuroinflammation and hypertension. Methods and Results OSA was induced in 8-week-old male rats. After 2 weeks of apneas, lymphocytes were isolated from aorta, brain, cecum, ileum, mesenteric lymph node, and spleen for flow cytometry. To examine the role of interleukin-17a, a monoclonal antibody was administered to neutralize interleukin-17a. Lymphocytes originating from the gut were tracked by labeling with carboxyfluorescein succinimidyl ester dye. OSA led to a significant decrease in T regulatory cells along with an increase in T helper (TH) 17 cells in the ileum, cecum, and brain. Interleukin-17a neutralization significantly reduced blood pressure, increased T regulatory cells, and decreased TH1 cells in the ileum, cecum, and brain of OSA rats. TH1, TH2, and TH17 cells from the gut were found to migrate to the mesenteric lymph node, spleen, and brain with increased frequency in rats with OSA. Conclusions OSA induces a proinflammatory response in the gut and brain that involves interleukin-17a signaling. Gut dysbiosis may serve as the trigger for gut and neuroinflammation, and treatments to prevent or reverse gut dysbiosis may prove useful in reducing neuroinflammation and hypertension.

Indole Propionic Acid Increases T Regulatory Cells and Decreases T Helper 17 Cells and Blood Pressure in Mice with Salt-Sensitive Hypertension.

Hypertension affects over a billion adults worldwide and is a major risk factor for cardiovascular disease. Studies have reported that the microbiota and its metabolites regulate hypertension pathophysiology. Recently, tryptophan metabolites have been identified to contribute to and inhibit the progression of metabolic disorders and cardiovascular diseases, including hypertension. Indole propionic acid (IPA) is a tryptophan metabolite with reported protective effects in neurodegenerative and cardiovascular diseases; however, its involvement in renal immunomodulation and sodium handling in hypertension is unknown. In the current study, targeted metabolomic analysis revealed decreased serum and fecal IPA levels in mice with L-arginine methyl ester hydrochloride (L-NAME)/high salt diet-induced hypertension (LSHTN) compared to normotensive control mice. Additionally, kidneys from LSHTN mice had increased T helper 17 (Th17) cells and decreased T regulatory (Treg) cells. Dietary IPA supplementation in LSHTN mice for 3 weeks resulted in decreased systolic blood pressure, along with increased total 24 h and fractional sodium excretion. Kidney immunophenotyping demonstrated decreased Th17 cells and a trend toward increased Treg cells in IPA-supplemented LSHTN mice. In vitro, naïve T cells from control mice were skewed into Th17 or Treg cells. The presence of IPA decreased Th17 cells and increased Treg cells after 3 days. These results identify a direct role for IPA in attenuating renal Th17 cells and increasing Treg cells, leading to improved sodium handling and decreased blood pressure. IPA may be a potential metabolite-based therapeutic option for hypertension.

Targeting of GPR65 with Small Molecules alters Th17 cell differentiation

Abstract GPR65 has been shown to be a critical regulator of Th17 pathogenicity. Loss of GPR65 in mice results in a decrease in Th17 cells and reduced susceptibility to experimental autoimmune encephalomyelitis. The CREB/CRTC2 pathway has emerged as an important regulator of immune function. We have previously shown that the CREB/CRTC2 pathway modulates autoimmune disease by promoting differentiation of Th17 cells. In this study we performed RNA-seq to identify Th17 genes regulated by the CREB/CRTC2 pathway. Our RNA-seq analysis led us to uncover the first mechanism of regulation of the orphan receptor GPR65 by the CREB/CRTC2 pathway. We show that GPR65 is a target of the CREB/CRTC2 pathway through expression studies and chromatin immunoprecipitation. In addition, we show that targeting of GPR65 with small molecules alters Th17 cell differentiation. Understanding the regulation of GPR65 will be crucial in developing small molecules to treat patients with Th17-mediated diseases.

Blockade of IL-18 signaling downregulates homing of effector CD4+ T cells to the gut mucosa and provides protection from experimental IBD

Abstract The immunological complexity of inflammatory bowel disease (IBD) results in persistent intestinal inflammation in millions of patients. As an epithelial cell-derived cytokine essential in the differentiation of CD4+ T helper cells, interleukin 18 (IL-18) is emerging as a therapeutic target for IBD. When naïve CD4+ T cells are stimulated with IL-18, the production of IFNγ and differentiation of Th1 cells increase. IL18R1−/− CD4+ T cells produce less IFNγ and inflammatory cytokines compared to WT. To examine the viability of targeting IL-18 in vivo, colitis was induced in WT, IL18−/−, and IL18R1−/− mice by DSS. In both knockouts, lower proportions of IFNγ- and IL17-producing CD4+ T cells were observed in the colon along with lesser overall severity relative to WT. To further investigate, we examined the interplay of antigen presenting cells and CD4+ T cells in vitro. IL18R1−/− Th1 cells had decreased α4β7 and GPR15 expression when co-cultured with WT BMDCs. Meanwhile, IL18R1−/− Tregs had decreased IFNγ and CCR9 expression when co-cultured with WT BMDCs that were stimulated with LPS and retinoic acid, suggesting that IL-18 may play a role in the differential gut homing of CD4+ T cell subsets. When CD4+ T cells are transferred to Rag2−/−, mice receiving IL18R1−/− T cells possess significantly lower proportions of α4β7+ Th1 cells while the proportion of Tregs in the colon are increased. Treatment of mice with DSS or Mdr1a−/− colitis with an oral IL-18 inhibitor (20 mg/kg) resulted in decreased Th1 cells and neutrophils, lower histological scores and improved disease severity. From converging data, we deduce that inhibition of IL-18 may alleviate exacerbated immune responses associated with IBD, yielding a favorable therapeutic.

Quercetin improves the imbalance of Th1/Th2 cells and Treg/Th17 cells to attenuate allergic rhinitis

Allergic rhinitis (AR) is a common inflammation that affects many people globally. Quercetin has anti-allergic biological activity in AR. Here, we aimed to explore the effects of quercetin on type 1 helper T (Th1)/Th2 and regulatory T cells (Treg)/Th17 balance. We established an ovalbumin (OVA)-induced mouse model and orally administered 20, 35, and 50 mg/kg/day quercetin. The nasal symptoms of mice were observed. The immunoglobulin levels, Treg/Th17-related factors, and pro-inflammatory factors were examined by ELISA. The differentiated inflammation cells were visualized using the diff-quick staining assay. The nasal histopathology was evaluated using H&E, periodic acid Schiff (PAS), and Giemsa staining assay. The results showed that quercetin attenuated OVA-induced rubbing and sneezing. Quercetin reduced IgE, IgG1, histamine, and increased IgG2 in serum. The number of differentiated inflammation cells and goblet cells in tissues that elevated by OVA was reduced by quercetin. Moreover, OVA increased the Treg cell percentage, the levels of IL-17, TGF-β, IL-6, TNF-α, and decreased Th17 cell percentage, IL-10 and FOXP3 levels, while quercetin abrogated their levels induced by OVA. Additionally, quercetin inactivated the NF-κB pathway. Taken together, quercetin attenuated AR symptoms by balancing the Th1/Th2, Treg/Th17 ratios, and inactivating the NF-κB pathway. The results suggested that quercetin may use for AR treatment.

Endoplasmic reticulum stress in the intestinal epithelium initiates purine metabolite synthesis and promotes Th17 cell differentiation in the gut

Intestinal IL-17-producing T helper (Th17) cells are dependent on adherent microbes in the gut for their development. However, how microbial adherence to intestinal epithelial cells (IECs) promotes Th17 cell differentiation remains enigmatic. Here, we found that Th17 cell-inducing gut bacteria generated an unfolded protein response (UPR) in IECs. Furthermore, subtilase cytotoxin expression or genetic removal of X-box binding protein 1 (Xbp1) in IECs caused a UPR and increased Th17 cells, even in antibiotic-treated or germ-free conditions. Mechanistically, UPR activation in IECs enhanced their production of both reactive oxygen species (ROS) and purine metabolites. Treating mice with N-acetyl-cysteine or allopurinol to reduce ROS production and xanthine, respectively, decreased Th17 cells that were associated with an elevated UPR. Th17-related genes also correlated with ER stress and the UPR in humans with inflammatory bowel disease. Overall, we identify a mechanism of intestinal Th17 cell differentiation that emerges from an IEC-associated UPR.