Recent advances in understanding the molecular mechanisms of the development and function of Th17 cells

Sanmiao wan alleviates inflammation and exhibits hypouricemic effect in an acute gouty arthritis rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Sanmiao wan (SMW), a classical traditional Chinese medicine (TCM) formula, has been employed to treat gouty diseases in clinic as early as Yuan dynasty. It shows remarkably therapeutic effects in acute gouty arthritis (GA). However, the potential mechanisms of SMW are still not fully revealed.

AIM OF THE STUDY

The objective of this project is to evaluate the pharmacological effects and possible mechanisms of SMW in a rat model of acute GA.

MATERIALS AND METHODS

Monosodium urate (MSU) suspension was injected into the ankle joint of rats to establish acute GA model. The inflammation was evaluated by measuring the posterior ankle diameter. The pathological status of synovial tissue was assessed by hematoxylin eosin (HE), Masson, and picrosirius red staining. The level of IL-6 was measured using ELISA kit. The levels of blood urea nitrogen (BUN), creatinine (CR), UA (uric acid), and xanthine oxidase (XOD) in the serum were measured using standard diagnostic kits. The percentage of Th17 cells in blood samples was performed using flow cytometry. Moreover, RT-qPCR was performed to examine the mRNA level of RANK, RORγt, RANKL, and STAT3 in the synovial tissue. Furthermore, immunofluorescence was carried out to assess the expression of STAT3 in the synovial tissue.

RESULTS

SMW effectively alleviated the inflammation and improved the pathological status of the ankle joint in rats with acute GA. It significantly suppressed the release of proinflammatory cytokine (IL-6). Meanwhile, the levels of UA, BUN, and CR were markedly reduced after SMW treatment. A remarkable reduction of XOD activity was observed in the study. Importantly, SMW treatment significantly reduced the frequency of Th17 cells, decreased the mRNA levels of RANK, RORγt, RANKL, and STAT3 in the synovial tissue. Furthermore, the suppression of STAT3 was also demonstrated using immunofluorescence in SMW-treated group.

CONCLUSION

SMW showed significant anti-inflammatory and hypouricemic effects in a rat model of GA. It is an effective TCM formula for GA therapy.

Relationship between IL-17A gene polymorphism and susceptibility to Kawasaki disease

OBJECTIVES

Kawasaki disease (KD) is the most common autoimmune vasculitis syndrome in children, which supposed be a complex polygenic disorder. Interleukin-17 (IL-17) is a member of the pro-inflammatory cytokine family, which has a strong pro-inflammatory effect and can participate in various acute and chronic inflammatory responses. This study aims to investigate the relationship between the single-nucleotide polymorphism (SNP) locus rs3819025 in the IL-17A gene and the susceptibility to KD.

METHODS

A total of 120 patients with KD who met the diagnostic criteria (the KD group) and 120 healthy children (the control group) were enrolled retrospectively in this study. Polymerase chain reaction (PCR) and DNA direct sequencing were used to detect the SNPs of children in the 2 groups.

RESULTS

The frequencies of GG, GA, and AA genotypes of rs3819025 locus in the IL-17A gene in the KD group were 82.5%, 17.5%, and 0, respectively, and the frequencies of GG, GA, and AA genotypes in the control group were 72.5%, 22.5%, and 5.0%, respectively. There were significant differences in both genotype (χ2=7.524, P=0.023). The allele frequencies G and A of rs3819025 locus in the KD group were 91.25% and 8.75%, respectively, while those in the control group were 83.75% and 16.25%, respectively. There was significant difference between the 2 groups (χ2=6.171, P=0.013). The distribution frequencies of GG or GA genotype and G or A allele were 88.46% or 11.54% and 94.23% or 5.77% in the KD group with coronary artery lesion, respectively. The distribution frequencies of GG or GA genotype and G or A allele were 78.72% or 21.28% and 89.36% or 10.64% in the KD group without coronary artery lesion, respectively. There were no significant differences in genotype and allele frequencies of rs3819025 between the KD with coronary artery lesion group and the KD group without coronary artery lesion (both P>0.05). Besides, children with the allele A had a 2.023 times higher risk of KD than those without the allele A (χ2=6.171, P=0.013; OR=2.023, 95% CI 1.151 to 3.557).

CONCLUSIONS

The locus rs3819025 in the IL-17A gene is associated with the pathogenesis of KD. The allele A of the locus rs3819025 in the IL-17A gene may be a risk factor for KD.

The potential roles of Th17 cells in the pathogenesis of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is a T cell-mediated chronic autoimmune disease, whose pathogenesis and etiology are not entirely understood. OLP is characterized by subepithelial lymphocyte infiltration and elevated intra-epithelial lymphocytes. The majority of lamina propria lymphocytes are CD4⁺ T cells. CD4⁺ helper T (Th) cells play a crucial role in activating CD8⁺ cytotoxic T cells (CTLs) through interactions and cytokine production. Th1 and Th2 cells are well-accepted to be associated with OLP pathogenesis. However, OLP treatment is challenging yet, the more information we have about the pathology of OLP, the easier it will be treated. With the discovery of Th17 cells in recent years and the demonstration of their role in autoimmune disease, many researchers started to investigate the role of Th17 in the pathogenesis of OLP.

METHODS

To make up this review, studies covering the role of TH17 in different types of lichen planus were selected from major databases.

RESULTS

As we review in this article, Th17 cells and their signature cytokines play an important role in OLP pathogenesis. As well, utilizing some anti-IL-17 antibodies showed promising results in improving the disease; however, more studies are still needed to better understand and treat OLP.

Itaconate ameliorates autoimmunity by modulating T cell imbalance via metabolic and epigenetic reprogramming

Dysregulation of Th17 and Treg cells contributes to the pathophysiology of many autoimmune diseases. Herein, we show that itaconate, an immunomodulatory metabolite, inhibits Th17 cell differentiation and promotes Treg cell differentiation by orchestrating metabolic and epigenetic reprogramming. Mechanistically, itaconate suppresses glycolysis and oxidative phosphorylation in Th17- and Treg-polarizing T cells. Following treatment with itaconate, the S-adenosyl-L-methionine/S-adenosylhomocysteine ratio and 2-hydroxyglutarate levels are decreased by inhibiting the synthetic enzyme activities in Th17 and Treg cells, respectively. Consequently, these metabolic changes are associated with altered chromatin accessibility of essential transcription factors and key gene expression in Th17 and Treg cell differentiation, including decreased RORγt binding at the Il17a promoter. The adoptive transfer of itaconate-treated Th17-polarizing T cells ameliorates experimental autoimmune encephalomyelitis. These results indicate that itaconate is a crucial metabolic regulator for Th17/Treg cell balance and could be a potential therapeutic agent for autoimmune diseases.

Th17 Cells: Orchestrators of Mucosal Inflammation and Potential Therapeutic Targets

T helper 17 (Th17) cells represent a specialized subgroup of effector CD4+ T cells known for their role in provoking neutrophil-driven tissue inflammation, particularly within mucosal tissues. Although they are pivotal for defending the host against extracellular bacteria and fungi, they have also been associated with development of various T cell-mediated inflammatory conditions, autoimmune diseases, and even cancer. Notably, Th17 cells exhibit a dual nature, with different Th17 cell subtypes showcasing distinct effector functions and varying capacities to incite autoimmune tissue inflammation. Furthermore, Th17 cells exhibit significant plasticity, which carries important functional implications, both in terms of their expression of cytokines typically associated with other effector T cell subsets and in their interactions with regulatory CD4+ T cells. The intricate balance of Th17 cytokines can also be a double-edged sword in inflammation, autoimmunity, and cancer. Within this article, we delve into the mechanisms that govern the differentiation, function, and adaptability of Th17 cells. We culminate with an exploration of therapeutic potentials in harnessing the power of Th17 cells and their cytokines. Targeted interventions to modulate Th17 responses are emerging as promising strategies for autoimmunity, inflammation, and cancer treatment. By precisely fine-tuning Th17-related pathways, we may unlock new avenues for personalized therapeutic approaches, aiming to restore immune balance, alleviate the challenges of these disorders, and ultimately enhance the quality of life for individuals affected by them.

Transcriptome analysis reveals the diverse response of pearl oyster Pinctada fucata martensii after different PAMP stimulation

Bivalves have evolved effective strategies to combat different pathogens in the environment. They rely on innate immunity to deal with the invasion of various bacteria, viruses, and other microorganisms. However, the molecular mechanisms underlying the responses remain largely unknown. Herein, we constructed 21 transcriptomes of the hemocytes after lipopolysaccharide (LPS), peptidoglycan (PGN) and polyinosinic-polycytidylic acid (poly(I:C)) stimulation to investigate the molecular mechanisms underlying adaptations and plastic responses to different pathogen-related molecular patterns (PAMPs) in pearl oyster Pinctada fucata martensii. Transcriptome analysis revealed 1986-3427 responsive genes enriched in the major immune and cell cycle-related pathways at different times after PAMP stimulation, and the expression patterns of genes under these pathways are complex and diverse. Moreover, "lysosomes" were enriched 6 h after LPS and PGN stimulation, while "peroxisomes" were only enriched in poly(I:C) group. These results suggest different response strategies of pearl oyster to different PAMPs. Furthermore, we identified 261 pattern-recognition receptors (PRRs) including 4 retinoic acid-inducible gene I-like receptors, 38 NOD-like receptors, 83 Toll-like receptors, and 136 C-type lectins in the genome of P. f. martensii. The diverse expression patterns of these PRRs after different PAMP stimulation indicated that pearl oyster evolved complex and specific recognition systems due to tandem repeat and diverse domain combination, which may help pearl oyster cope with the different pathogens in the environment. The present study improved our understanding of the molecular response of pearl oyster to different PAMP stimulation.

DYRK1A reinforces epithelial-mesenchymal transition and metastasis of hepatocellular carcinoma via cooperatively activating STAT3 and SMAD

Background

Hepatocellular carcinoma (HCC) accounts for the majority of liver cancer cases, while metastasis is considered the leading cause of HCC-related death. However, the currently available treatment strategies for efficient suppression of metastasis are limited. Therefore, novel therapeutic targets to inhibit metastasis and effectively treat HCC are urgently required.

Methods

Wound healing and Transwell assays were used to determine the migration and invasion abilities of HCC cells in vitro. Quantitative real-time PCR (qRT-PCR), protein array, immunofluorescence, and immunoprecipitation experiments were used to study the mechanism of DYRK1A-mediated metastasis. A tail vein metastasis model and H&E staining were utilized to assess metastatic potential in vivo.

Results

The results of the current study demonstrated that dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) was upregulated in HCC tissues compared with normal liver tissues. Additionally, the level of DYRK1A was increased in primary HCC tissues of patients with metastasis compared with those of patients without metastasis, and DYRK1A overexpression correlated with worse outcomes in liver cancer patients. Gain- and loss-of-function studies suggested that DYRK1A enhanced the invasion and migration abilities of HCC cells by promoting epithelial-mesenchymal transition (EMT). Regarding the promoting effect of DYRK1A on cell invasion, the results showed that DYRK1A was coexpressed with TGF-β/SMAD and STAT3 signalling components in clinical tumour samples obtained from patients with HCC. DYRK1A also activated TGF-β/SMAD signalling by interacting with tuberous sclerosis 1 (TSC1) and enhanced metastasis of HCC cells by activating STAT3. Furthermore, DYRK1A promoted EMT by cooperatively activating STAT3/SMAD signalling.

Conclusion

Overall, the present study not only uncovered the promoting effect of DYRK1A on HCC metastasis and revealed the mechanism but also provided a new approach to predict and treat metastatic HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00817-y.

Examining micro-ribonucleic acids as diagnostic and therapeutic prospects in autoimmune hepatitis

INTRODUCTION

Micro-ribonucleic acids modulate the immune response by affecting the post-transcriptional expression of genes that influence the proliferation and function of activated immune cells, including regulatory T cells. Individual expressions or patterns in peripheral blood and liver tissue may have diagnostic value, reflect treatment response, or become therapeutic targets. The goals of this review are to present the properties and actions of micro-ribonucleic acids, indicate the key individual expressions in autoimmune hepatitis, and describe prospective clinical applications in diagnosis and management.

AREAS COVERED

Abstracts were identified in PubMed using the search words "microRNAs", "microRNAs in liver disease", and "microRNAs in autoimmune hepatitis". The number of abstracts reviewed exceeded 2000, and the number of full-length articles reviewed was 108.

EXPERT OPINION

Individual micro-ribonucleic acids, miR-21, miR-122, and miR-155, have been associated with biochemical severity, histological grade of inflammation, and pivotal pathogenic mechanisms in autoimmune hepatitis. Antisense oligonucleotides that down-regulate deleterious individual gene expressions, engineered molecules that impair targeting of gene products, and drugs that non-selectively up-regulate the biogenesis of potentially deficient gene regulators are feasible treatment options. Micro-ribonucleic acids constitute an under-evaluated area in autoimmune hepatitis that promises to improve diagnosis, pathogenic concepts, and therapy.

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.

Evaluating the Effects of Epigallocatechin-3-Gallate on HIF-1α Protein and RORC Gene Expression in Peripheral Blood Mononuclear Cells in Patients With Multiple Sclerosis

Introduction:

Multiple Sclerosis (MS) is the chronic inflammation of the Central Nervous System (CNS) and autoimmune disease. MS is most widely considered to be mediated by the activation of myelin-specific T CD4⁺ cells as well as TH1 and TH17 cells. TH17 cells are involved in the pathogenesis of MS in various manners. HIF-1α and RORC are required for the natural differentiation of TH17; they are essential transcription factors for the evolution of TH17 cells. Numerous studies indicated that Epigallocatechin Gallate (EGCG) presents immunomodulatory and anti-inflammatory effects. This study investigated the effects of EGCG on normoxic HIF-1α and RORC2 expression in PBMCs among MS patients.

Methods:

Peripheral Blood Mononuclear Cells (PBMCs) were isolated from the whole blood of new cases of MS. The cells were cultured in the presence of a different concentration of EGCG (25, 50,100μM) for 18 and 48 hours. Next, HIF-1α and RORC2 level expressions were measured by Enzyme-Linked Immunosorbent Assay (ELISA) and Real-Time PCR, respectively.

Results:

The results showed that EGCG significantly decreased RORC2 gene expression. EGCG did not affect the level of HIF-1α.

Conclusion:

However, EGCG did not influence the level of HIF-1α. Our present data has led us to conclude that EGCG could be considered as an anti-inflammatory agent may serve as an achievable therapeutic agent for MS.

Immunomodulatory Effects of Curcumin in Rheumatoid Arthritis: Evidence from Molecular Mechanisms to Clinical Outcomes

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disorder characterized by the destruction of the joint and bone resorption. The production of pro-inflammatory cytokines and chemokines, dysregulated functions of three important subtypes of T helper (T_H) cells including T_H1, T_H17, and regulator T (Treg) cells are major causes of the initiation and development of RA. Moreover, B cells as a source of the production of several autoantibodies play key roles in the pathogenesis of RA. The last decades have seen increasingly rapid advances in the field of immunopharmacology using natural origin compounds for the management of various inflammatory diseases. Curcumin, a main active polyphenol compound isolated from turmeric, curcuma longa, possesses a wide range of pharmacologic properties for the treatment of several diseases. This review comprehensively will assess beneficial immunomodulatory effects of curcumin on the production of pro-inflammatory cytokines and also dysregulated functions of immune cells including T_H1, T_H17, Treg, and B cells in RA. We also seek the clinical efficacy of curcumin for the treatment of RA in several recent clinical trials. In conclusion, curcumin has been found to ameliorate RA complications through modulating inflammatory and autoreactive responses in immune cells and synovial fibroblast cells via inhibiting the expression or function of pro-inflammatory mediators, such as nuclear factor-κB (NF-κB), activated protein-1 (AP-1), and mitogen-activated protein kinases (MAPKs). Of note, curcumin treatment without any adverse effects can attenuate the clinical symptoms of RA patients and, therefore, has therapeutic potential for the treatment of the diseases.

Effect of uremic serum on Th17/Treg cell balance and endoplasmic reticulum stress in rats

BACKGROUND/AIMS

The imbalance of T helper 17 (Th17) and regulatory T (Treg) cells exists in the occurrence and development of various diseases. Endoplasmic reticulum stress (ERS) is an important self-protective cellular response to harmful stimuli, such as uremic environment. The objective of this study was to investigate the Th17/Treg cell balance and ERS in a uremic environment and analyze the relationship between them.

METHODS

(1) The rat spleen lymphocytes were extracted and treated with thapsigargin (inducer of ERS) and sodium citrate. The proportion of Th17 and Treg cells were then detected. (2) The uremic serum-cultured lymphocytes were used and divided into three groups: non-uremic serum group, uremic serum group, and uremic serum + sodium citrate group. Afterward, the proportion of Th17/Treg cells and the expression of ERS-related proteins (GRP78 and CHOP) were detected.

RESULTS

Thapsigargin had no significant effect on the proportion of Th17 cells within a limited concentration range, but it could reduce the proportion of Treg cells, sodium citrate had a negative influence on the deviation of Th17/Treg cells treated with thapsigargin. Uremic serum treatment reduced the proportion of Treg cells, resulting in an increase of the Th17/Treg ratio. However, sodium citrate had no influence on the deviation of Th17/Treg cells treated by uremic serum. Sodium citrate reduced the elevation of ERS-related proteins induced by uremic serum.

CONCLUSIONS

Uremic serum can lead to the imbalance of Th17/Treg cells as well as ERS, suggesting that ERS is one of the mechanisms of the imbalance of Th17/Treg cells induced by uremic serum. Sodium citrate can inhibit ERS induced by uremic serum.

Sarcoidosis and the mTOR, Rac1, and Autophagy Triad

Sarcoidosis is an enigmatic multisystem disease characterized by the development and accumulation of granulomas: a compact collection of macrophages that have differentiated into epithelioid cells and which are associated with T helper (Th)1 and Th17 cells. Although no single causative factor has been shown to underlie sarcoidosis in humans, its etiology has been related to microbial, environmental, and genetic factors. We examine how these factors play a role in sarcoidosis pathogenesis. Specifically, we propose that dysfunction of mTOR, Rac1, and autophagy-related pathways not only hampers pathogen or nonorganic particle clearance but also participates in T cell and macrophage dysfunction, driving granuloma formation. This concept opens new avenues for potentially treating sarcoidosis and may serve as a blueprint for other granulomatous disorders.

Application of Herbaceous Medications for Inflammatory Bowel Disease as a Complementary and Alternative Therapy

BACKGROUND

Conventional medicine for the treatment of IBD is prevailingly composed of sulfadiazine, 5-aminosalicylic acid, glucocorticoid, and immunosuppressants, which have the merits of alleviating intestine inflammation, but long-term use of these drugs may cause toxic side effects; additionally, these drugs may be expensive. In the pursuit of novel and more economic therapies, patients may increasingly look at complementary and alternative medicine (CAM). Recently, CAM is increasingly favored by the general public on account of its safety, low toxicity, and effectiveness. As a branch of CAM, herbal plants and their extracts have a significant effect on the treatment of IBD. Treatment of IBD with herbaceous plants has been reported, but specific mechanisms and effects have not yet been elaborated.

METHODS

English abstracts were identified in PubMed and Science Direct by multiple search terms, such as "herbal," "CAM," "IBD," "ulcerative colitis," "abdominal pain," and so on. Full-length articles were selected for review.

RESULTS

Herbaceous plants and their extracts have been shown to be effective against IBD in many studies, and herbaceous plants may be effective in treating symptoms such as abdominal pain, diarrhea, mucus, and bloody stools.

CONCLUSIONS

Herbal medications could be used as a complementary and alternative treatment for IBD, but they require more rigorous scientific testing.

Th17 cells promote tumor growth in an immunocompetent orthotopic mouse model of prostate cancer

Interleukin-17 (IL-17) has been demonstrated to promote development of a variety of cancers including prostate cancer in genetically modified mouse models. IL-17 is the main product secreted by T helper 17 (Th17) cells. A recent study has shown that Th17 cells and related genes are upregulated in human prostate cancers. However, there is no direct experimental evidence to demonstrate Th17's role in prostate cancer. In the present study, we co-implanted mouse prostate cancer MPC3-luc cells with Th17-polarized mouse splenocytes in the prostate of immunocompetent C57BL/6J male mice. We found that Th17-polarized splenocytes promoted orthotopic allograft prostate tumor growth compared to the control splenocytes. The numbers of IL-17-positive lymphocytes and macrophages were higher in the prostate tumors grown from co-implantation of MPC3-luc cells and Th17-polarized splenocytes, compared to the prostate tumors grown from co-implantation of MPC3-luc cells and control splenocytes. Our findings provide the first direct experimental evidence that Th17 cells may promote prostate cancer growth.

Th17 Cells and the IL-23/IL-17 Axis in the Pathogenesis of Periodontitis and Immune-Mediated Inflammatory Diseases

Innate immunity represents the semi-specific first line of defense and provides the initial host response to tissue injury, trauma, and pathogens. Innate immunity activates the adaptive immunity, and both act highly regulated together to establish and maintain tissue homeostasis. Any dysregulation of this interaction can result in chronic inflammation and autoimmunity and is thought to be a major underlying cause in the initiation and progression of highly prevalent immune-mediated inflammatory diseases (IMIDs) such as psoriasis, rheumatoid arthritis, inflammatory bowel diseases among others, and periodontitis. Th1 and Th2 cells of the adaptive immune system are the major players in the pathogenesis of IMIDs. In addition, Th17 cells, their key cytokine IL-17, and IL-23 seem to play pivotal roles. This review aims to provide an overview of the current knowledge about the differentiation of Th17 cells and the role of the IL-17/IL-23 axis in the pathogenesis of IMIDs. Moreover, it aims to review the association of these IMIDs with periodontitis and briefly discusses the therapeutic potential of agents that modulate the IL-17/IL-23 axis.

Interleukin-17A polymorphisms predict the response and development of tolerance to FOLFOX chemotherapy in colorectal cancer treatment

Polymorphic variants in IL-17A gene were differentially associated with colorectal cancer (CRC) susceptibility but their link with response and toxicity to CRC treatment have not yet been evaluated. We investigated association between seven IL-17A variants with the response and toxicity to CRC treatment in 294 patients with CRC. IL-17A genotyping was done by real-time PCR. MAF of rs3748067 was significantly higher in CRC cases resistant to FOLFOX treatment (R+) than non resistant (R-). Significantly higher rs3804513 MAF was noted in R+ versus R- colon cancer (CC). Higher rs2275913 and rs10484879, and reduced rs3804513 MAF were seen in rectal cancer (RC) tolerant to FOLFOX (T+) compared to (T-) patients. Strong association of rs3819025, rs3804513, and rs7747909 was found with tolerance to RC treatment. rs3748067 was associated with FOLFOX tolerance in CC but not RC. Significant higher frequency of AGGCAGG and GAGCAGG haplotypes was seen among R + CC, thus assigning non-favorable nature to these haplotypes. Higher and lower frequencies of GAGTAAG and AGGCTGA haplotypes, respectively, were observed in T + RC, thereby assigning FOLFOX-tolerant and non-tolerant nature to these haplotypes. The obtained results suggest that IL-17A variants and haplotypes may be a target for future management of CRC treatment.

Transcriptional regulation of CD4+ TH cells that mediate tissue inflammation

Acquired and genetic immunodeficiencies have revealed an indispensable role for CD4⁺ T cells in the induction of protective host immune responses against a myriad of microbial pathogens. Influenced by the cytokines present in the microenvironment, activated CD4⁺ T cells may differentiate into several highly-specialized helper subsets defined by the production of distinct signature cytokines tailored to combat diverse classes of pathogens. The process of specification and differentiation is controlled by networks of core, master, and accessory transcription factors, which ensure that CD4⁺ T helper (T_H ) cell responses mounted against an invading microbe are of the correct specificity and type. However, aberrant activation or inactivation of transcription factors can result in sustained and elevated expression of immune-related genes, leading to chronic activation of CD4⁺ T_H  cells and organ-specific autoimmunity. In this review, we provide an overview of the molecular basis of CD4⁺ T_H  cell differentiation and examine how combinatorial expression of transcription factors, which promotes genetic plasticity of CD4⁺ T_H  cells, can contribute to immunological dysfunction of CD4⁺ T_H responses. We also discuss recent studies which highlight the potential of exploiting the genetic plasticity of CD4⁺ T_H  cells in the treatment of autoimmune and other immune-mediated disorders.

T helper 17 cell/regulatory T-cell imbalance in hidradenitis suppurativa/acne inversa: the link to hair follicle dissection, obesity, smoking and autoimmune comorbidities

BACKGROUND

Disintegration of the infundibula of terminal hair follicles (HFs) in intertriginous skin areas exhibits the histological hallmark of hidradenitis suppurativa (HS)/acne inversa, featuring a dissecting terminal hair folliculitis. Elevated serum levels of interleukin (IL)-17 and local increase in the ratio of proinflammatory T helper (Th)17 cells and anti-inflammatory regulatory T cells (Tregs) have been reported. Perifollicular Tregs play a key role in HF stem cell homeostasis and infundibular integrity.

OBJECTIVES

In this review, we evaluate the Th17/Treg ratio in HS, its aggravating conditions and associated comorbidities. Furthermore, we intended to clarify whether drugs with reported beneficial effects in the treatment of HS readjust the deviated Th17/Treg axis.

METHODS

PubMed-listed, peer-reviewed original research articles characterizing Th17/Treg regulation in HS/acne inversa and associated comorbidities were selected for this review.

RESULTS

This review presents HS as a disease that exhibits an increased Th17/Treg ratio. Perifollicular deficiencies in Treg numbers or function may disturb HF stem cell homeostasis, initiating infundibular dissection of terminal HFs and perifollicular inflammation. The Th17/Treg imbalance is aggravated by obesity, smoking and decreased Notch signalling. In addition, HS-associated autoimmune diseases exhibit a disturbed Th17/Treg axis resulting in a Th17-dominant state. All drugs that have beneficial effects in the treatment of HS normalize the Th17/Treg ratio.

CONCLUSIONS

HS immunopathogenesis is closely related to deviations of the Th17/Treg balance, which may negatively affect Treg-controlled HF stem cell homeostasis and infundibular integrity. Pharmacological intervention should not only attenuate Th17/IL-17 signalling, but should also improve Treg function in order to stabilize HF stem cell homeostasis and infundibular integrity.

Ecdysteroidogenesis and development in Heliothis virescens (Lepidoptera: Noctuidae): Focus on PTTH-stimulated pathways

Post-embryonic development and molting in insects are regulated by endocrine changes, including prothoracicotropic hormone (PTTH)-stimulated ecdysone secretion by the prothoracic glands (PGs). In Lepidoptera, two pathways are potentially involved in PTTH-stimulated ecdysteroidogenesis, mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/protein kinase B/target of rapamycin (PI3K/Akt/TOR). We investigated the potential roles of both these pathways in Heliothis virescens ecdysteroidogenesis. We identified putative proteins belonging to MAPK and PI3K/Akt/TOR signaling cascades, using transcriptomic analyses of PGs from last (fifth) instar larvae. Using western blots, we measured the phosphorylation of 4E-BP and S6K proteins, the main targets of TOR, following the in vitro exposure of PGs to brain extract containing PTTH (hereafter referred to as PTTH) and/or the inhibitors of MAPK (U0126), PI3K (LY294002) or TOR (rapamycin). Next, we measured ecdysone production, under the same experimental conditions, by enzyme immunoassay (EIA). We found that in Heliothis virescens last instar larvae, both pathways modulated PTTH-stimulated ecdysteroidogenesis. Finally, we analyzed the post-embryonic development of third and fourth instar larvae fed on diet supplemented with rapamycin, in order to better understand the role of the TOR pathway in larval growth. When rapamycin was added to the diet of larvae, the onset of molting was delayed, the growth rate was reduced and abnormally small larvae/pupae with high mortality rates resulted. In larvae fed on diet supplemented with rapamycin, the growth of PGs was suppressed, and ecdysone production and secretion were inhibited. Overall, the in vivo and in vitro results demonstrated that, similarly to Bombyx mori, MAPK and PI3K/Akt/TOR pathways are involved in PTTH signaling-stimulated ecdysteroidogenesis, and indicated the important role of TOR protein in H. virescens systemic growth.

Association of interleukin-17A polymorphisms with the risk of colorectal cancer: A case-control study

BACKGROUND

Interleukin (IL)-17A is proinflammatory cytokine produced by Th17 cells, which play key, but sometimes inconsistent role in autoimmunity and cancer. Polymorphic variants in IL-17A gene were differentially associated with susceptibility to cancer, including colorectal cancer (CRC).

AIM

We investigated the association between six IL-17A gene variants (rs3819024, rs2275913, rs3819025, rs10484879, rs7747909, and rs3748067) with CRC susceptibility in Tunisians.

SUBJECTS AND METHODS

Retrospective case-control study. Study subjects comprised 293 patients with CRC, and 268 age-, gender-, and BMI-matched healthy controls. IL-17A genotyping was done by real-time PCR, with defined clusters.

RESULTS

Of the seven tested IL-17A tag-SNPs, minor allele frequency (MAF) of rs10484879 was significantly higher in CRC patients than control subjects. Heterozygous rs10484879 [OR (95% CI) = 2.63 (1.64-4.21)] was associated with higher risk, while carriage of heterozygous rs3748067 genotype was associated with reduced risk of CRC [OR (95% CI) = 0.56 (0.37-0.84)], respectively. Carriage of rs10484879 minor allele correlated with positive family history of CRC and other cancers (P = 0.002), CRC staging (P = 0.044), CRC treatment (P = 0.038), and with chemo body reaction (P = 0.001). Of the 7 IL-17A variants, 4 were in linkage disequilibrium, hence allowing for construction of 4-locus haplotypes. Varied linkage disequilibrium (LD) was noted between the even tested IL-17A variants, and further analysis was limited to only 4-locus (rs3819024-rs2275913- rs10484879-rs7747909). Haploview analysis identified the 4-locus IL-17A haplotypes AGTG (P < 0.011), and GATG (P = 0.036) to be positively associated with CRC, after controlling key covariates.

CONCLUSION

IL-17A rs10484879 SNP, and IL-17A haplotypes AGGTG and GAGTG constitute independent factors of CRC susceptibility. We propose that IL-17A may be a target for future CRC immunotherapy.

Identification of novel quinazolinedione derivatives as RORγt inverse agonist

Novel small molecules were synthesized and evaluated as retinoic acid receptor-related orphan receptor-gamma t (RORγt) inverse agonists for the treatment of inflammatory and autoimmune diseases. A hit compound, 1, was discovered by high-throughput screening of our compound library. The structure-activity relationship (SAR) study of compound 1 showed that the introduction of a chlorine group at the 3-position of 4-cyanophenyl moiety increased the potency and a 3-methylpentane-1,5-diamide linker is favorable for the activity. The carbazole moiety of 1 was also optimized; a quinazolinedione derivative 18i suppressed the increase of IL-17A mRNA level in the lymph node of a rat model of experimental autoimmune encephalomyelitis (EAE) upon oral administration. These results indicate that the novel quinazolinedione derivatives have great potential as orally available small-molecule RORγt inverse agonists for the treatment of Th17-driven autoimmune diseases. A U-shaped bioactive conformation of this chemotype with RORγt protein was also observed.

L161982 alleviates collagen-induced arthritis in mice by increasing Treg cells and down-regulating Interleukin-17 and monocyte-chemoattractant protein-1 levels

BACKGROUND

To investigate the effects and potential mechanism of L161982 (a kind of EP4 antagonist) on the collagen-induced arthritis (CIA) mice model.

METHODS

The CIA mice model were first established by immunizing with Chicken Type II Collagen on DBA/1 mice. The CIA groups were administered once a day for 2 weeks with either 5 mg/kg L161982 by intraperitoneal injections (IP), 200 U celecoxib by intragastrical injections, or 100 μl PBS (IP). At the end of the study, total arthritis score and histopathologic examination were assessed to determine CIA severity. The plasma and tissue expressions of IL-17 and monocyte chemoattractant protein-1 (MCP-1) were detected by enzyme-linked immunosorbent assay (ELISA) and Immunohistochemical staining (IHC) respectively; The number of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Treg) determined as a proportion of total CD4⁺ cells in the lymph nodes and spleen. We also tested the proliferation of isolated Tregs and the ratio of Th17 polarization of Naïve T cells under the treatment of L161982 by BrdU assay and flow cytometry respectively.

RESULTS

CIA mice treated with L161982 showed reduced arthritis scores, joint swellings, cracked cartilage surface, and less hyperplasia in the connective tissue of the articular cavity. Plasma and tissue IL-17 and MCP-1 decreased, while the proportion of Treg cells is increased both in the spleen and lymph nodes of CIA mice. Otherwise, L161982 have no direct effect on Tregs proliferation; a decreased tendency of Th17 polarization in vitro were observed in L161982-treated naïve T cells.

CONCLUSION

Although less effective than Celecoxib, L161982 also resulted in a reduction of ankle joint inflammation in CIA mice. L161982 reduces the RA severity in CIA mice through inhibition of IL-17 and MCP-1, increasing Treg cells, and reducing inflammation. The mechanism of the reduction of IL-17 in plasma or tissue after administration of L161982 might be potentially derived from the suppression of CD4⁺ T cells differentiation into Th-17 cells.

Increased T-helper 17 cell differentiation mediated by exosome-mediated microRNA-451 redistribution in gastric cancer infiltrated T cells

MicroRNA (miR)‐451 is a cell metabolism‐related miRNA that can mediate cell energy‐consuming models by several targets. As miR‐451 can promote mechanistic target of rapamycin (mTOR) activity, and increased mTOR activity is related to increased differentiation of T‐helper 17 (Th17) cells, we sought to investigate whether miR‐451 can redistribute from cancer cells to infiltrated T cells and enhance the distribution of Th17 cells through mTOR. Real‐time PCR was used for detecting expression of miR‐451 in gastric cancer, tumor infiltrated T cells and exosomes, and distribution of Th17 was evaluated by both flow cytometry and immunohistochemistry (IHC). Immunofluorescence staining was used in monitoring the exosome‐enveloped miR‐451 from cancer cells to T cells with different treatments, and signaling pathway change was analyzed by western blot. miR‐451 decreased significantly in gastric cancer (GC) tissues but increased in infiltrated T cells and exosomes; tumor miR‐451 was negatively related to infiltrated T cells and exosome miR‐451. Exosome miR‐451 can not only serve as an indicator for poor prognosis of post‐operation GC patients but is also related to increased Th17 distribution in gastric cancer. miR‐451 can redistribute from cancer cells to T cells with low glucose treatment. Decreased 5′ AMP‐activated protein kinase (AMPK) and increased mTOR activity was investigated in miR‐451 redistributed T cells and the Th17 polarized differentiation of these T cells were also increased. Exosome miR‐451 derived from tumor tissues can serve as an indicator for poor prognosis and redistribution of miR‐451 from cancer cells to infiltrated T cells in low glucose treatment can enhance Th17 differentiation by enhancing mTOR activity.

The mechanisms of IL-17A on promoting tumor metastasis

In recent decades, extensive studies have indicated that IL-17A plays an important role in tumor progression and metastasis, but the underlying mechanisms are not immediately clear. In this review, we examined the literature from the recent years concerning the study of IL-17A in four kinds of tumor transfer paths, including hematogenous metastasis, lymphatic metastasis, local invasion and transcoelomic metastasis, to summarize the roles and underlying mechanisms of IL-17A on tumor metastasis.

The MicroRNA-183-96-182 Cluster Promotes T Helper 17 Cell Pathogenicity by Negatively Regulating Transcription Factor Foxo1 Expression

T helper 17 (Th17) cells are key players in autoimmune diseases. However, the roles of non-coding RNAs in Th17 cell development and function are largely unknown. We found that deletion of the endoribonuclease-encoding Dicer1 specifically in Th17 cells protected mice from experimental autoimmune encephalomyelitis. We found that the Dicer1-regulated microRNA (miR)-183-96-182 cluster (miR-183C) was highly expressed in Th17 cells and was induced by cytokine IL-6-STAT3 signaling. miR-183C expression enhanced pathogenic cytokine production from Th17 cells during their development and promoted autoimmunity. Mechanistically, miR-183C in Th17 cells directly repressed expression of the transcription factor Foxo1. Foxo1 negatively regulated the pathogenicity of Th17 cells in part by inhibiting expression of cytokine receptor IL-1R1. These findings indicate that the miR-183C drives Th17 pathogenicity in autoimmune diseases via inhibition of Foxo1 and present promising therapeutic targets.

Skin Immunity

Skin is the largest organ of the body with a complex network of multitude of cell types that perform plastic and dynamic cellular communication to maintain several vital processes such as inflammation, immune response including induction of tolerance and disease prevention, wound healing, and angiogenesis. Of paramount importance are immunological functions of the skin that protect from harmful exposure coming from external and internal environments. Awareness of skin immunity can provide a better comprehension of inflammation, autoimmunity, cancer, graft-versus-host disease, vaccination, and immunotherapy approaches. This paper will update on what we currently know about immune sentinels contributing to skin immunity.

In vivo and in vitro phagocytosis of Leishmania (Leishmania) amazonensis promastigotes by B-1 cells

Leishmaniasis is caused by Leishmania parasites that infect several cell types. The promastigote stage of Leishmania is internalized by phagocytic cells and transformed into the obligate intracellular amastigote form. B-1 cells are a subpopulation of B cells that are able to differentiate in vitro and in vivo into mononuclear phagocyte-like cells with phagocytic properties. B-1 cells use several receptors for phagocytosis, such as the mannose receptor and third complement receptor. Leishmania binds to the same receptors on macrophages. In this study, we demonstrated that phagocytes derived from B-1 cells (B-1 CDP) were able to internalize promastigotes of L. (L.) amazonensis in vitro. The internalized promastigotes differentiated into amastigotes. Our results showed that the phagocytic index was higher in B-1 CDP compared to peritoneal macrophages and bone marrow-derived macrophages. The in vivo phagocytic ability of B-1 cells was also demonstrated. Parasites were detected inside purified B-1 cells after intraperitoneal infection with L. (L.) amazonensis promastigotes. Intraperitoneal stimulation with the parasites led to an increase in both IL-10 and TNF-α. These results highlight the importance of studying B-1 CDP cells as phagocytic cells that can participate and contribute to immunity to parasites.

Imbalance of Th17/Treg cells in pathogenesis of patients with human leukocyte antigen B27 associated acute anterior uveitis

Th17 and regulatory T cells, involved in the pathogenesis of several autoimmune diseases, are new lineages of CD4+ T helper cells. However, the role of their imbalance in human leukocyte antigen B27-associated acute anterior uveitis has not been elucidated. In our study, the percentages of Th17 and Treg cells, their molecular markers and related factors in peripheral blood of patients and healthy controls were measured by flow cytometry, real-time RT-PCR and ELISA. We observed a remarkable increase of CD4+ and CD4+IL-17+ T cells in peripheral blood of patients compared to controls. The molecular markers and related factors of Th17 cell were also showed a distinct elevation. Interestingly, we observed an obvious decrease of CD4+CD25+Foxp3+ T cells and Foxp3 mRNA level in patients. The ratio of Th17/Treg in patients was dramatically higher than controls. Moreover, the ratio of Th17/Treg cells had a more significantly positive correlation with the disease activity score than Th17 cells whereas Treg cells had a negative correlation. Our findings demonstrated a distinct increase of Th17 cells and a significant decrease of Treg cells in patients compared to controls. The imbalance of Th17 and Treg cells may play a vital role in the pathogenesis of the disease.

TGF-β-induced phosphorylation of Akt and Foxo transcription factors negatively regulates induced regulatory T cell differentiation

Transforming growth factor-β (TGF-β) is a pivotal cytokine in the differentiation of regulatory T cells, and Foxo transcription factors positively regulate this process. On the other hand, the function of Foxo transcription factors is negatively regulated by PI3K/Akt signaling, which is activated by TGF-β in many types of cells; yet the role of TGF-β in Akt activity and its downstream substrates in CD4⁺ T cells, including Foxo transcription factors, remains to be determined. Herein, we demonstrate that TGF-β selectively induces Akt phosphorylation at Ser473 but not at Thr308 in a class I_A PI3K-dependent manner in CD4⁺ T cells, resulting in the phosphorylation and inhibition of Foxo transcription factors and negatively regulating the differentiation of induced regulatory T cells (iTregs). These observations reveal a novel negative regulatory mechanism involving Akt and Foxo transcription factors induced by TGF-β in the iTreg differentiation process.

Rheumatoid arthritis onset in postmenopausal women: Does the ACPA seropositive subset result from genetic effects, estrogen deficiency, skewed profile of CD4(+) T-cells, and their interactions?

Rheumatoid arthritis (RA) incidence displays a differentiated age-dependent female-to-male ratio in which women outnumber men. Evidence that the peak incidence of RA in women coincides with menopause age, suggests a potential estrogenic role to disease etiology. Estrogens exert physiologically both stimulatory and inhibitory effects on the immune system. Epidemiologic and animal model studies with estrogen deprivation or supplementation suggested estrogens as to play, mainly, a protective role in RA immunopathology. In this review, we propose that some yet unidentified disturbances associated with estrogen circulating levels, differentiated by the menopausal status, play a major role in women's RA susceptibility. We focus on the interaction between estrogen deprivation and genetic risk alleles for anti-citrullinated protein antibodies (ACPA) seropositive RA, as a major driving force for increased immune reactivity and RA susceptibility, in postmenopausal women. This opens up new fields for research concerning the association among different irregular estrogenic conditions, the cytokine milieu, and age/menopausal status bias in RA.

The PI3K/Akt/PTEN/mTOR pathway: a fruitful target for inducing cell death in rheumatoid arthritis?

PI3K/Akt/mTOR signaling regulates diverse cellular processes. Abnormal PI3K/Akt/mTOR signaling is a characteristic feature of cancer. As such inhibition of PI3K/Akt/mTOR signaling using small molecule inhibitors has been a focus of recently developed anticancer drugs. Rheumatoid arthritis and psoriatic arthritis are autoimmune-mediated inflammatory diseases. PI3K signaling could now be targeted to determine its contribution to rheumatoid and psoriatic arthritis where deregulated proliferation and aberrant survival of activated immune cells, macrophages, monocytes, dendritic cells and synovial fibroblasts significantly overlap with abnormal growth of cancer cells. The results of some recent studies in psoriatic arthritis using PI3K signaling inhibitors suggests that small molecule inhibitor strategies directed at PI3K signaling may be a useful future therapy for immune-mediated arthritis.

Benzoxazepines Achieve Potent Suppression of IL-17 Release in Human T-Helper 17 (TH 17) Cells through an Induced-Fit Binding Mode to the Nuclear Receptor RORγ

RORγt, an isoform of the retinoic acid-related orphan receptor gamma (RORc, RORγ), has been identified as the master regulator of T-helper 17 (TH 17) cell function and development, making it an attractive target for the treatment of autoimmune diseases. Validation for this target comes from antibodies targeting interleukin-17 (IL-17), the signature cytokine produced by TH 17 cells, which have shown impressive results in clinical trials. Through focused screening of our compound collection, we identified a series of N-sulfonylated benzoxazepines, which displayed micromolar affinity for the RORγ ligand-binding domain (LBD) in a radioligand binding assay. Optimization of these initial hits resulted in potent binders, which dose-dependently decreased the ability of the RORγ-LBD to interact with a peptide derived from steroid receptor coactivator 1, and inhibited the release of IL-17 secretion from isolated and cultured human TH 17 cells with nanomolar potency. A cocrystal structure of inverse agonist 15 (2-chloro-6-fluoro-N-(4-{[3-(trifluoromethyl)phenyl]sulfonyl}-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl)benzamide) bound to the RORγ-LBD illustrated that both hydrophobic interactions, leading to an induced fit around the substituted benzamide moiety of 15, as well as a hydrogen bond from the amide NH to His479 seemed to be important for the mechanism of action. This structure is compared with the structure of agonist 25 (N-(2-fluorophenyl)-4-[(4-fluorophenyl)sulfonyl]-2,3,4,5-tetrahydro-1,4-benzoxazepin-6-amine ) and structures of other known RORγ modulators.

CD147/basigin limits lupus nephritis and Th17 cell differentiation in mice by inhibiting the interleukin-6/STAT-3 pathway

OBJECTIVE

Interleukin-17 (IL-17)-producing T cells (Th17 cells) play critical roles in the pathogenesis of immune-related diseases, including systemic lupus erythematosus. However, the fundamental mechanism regulating Th17 cell differentiation is not fully understood. Recently, we demonstrated that plasma levels of CD147/basigin (Bsg) in patients with lupus nephritis (LN) were closely associated with disease activity. but the molecular mechanism involving Bsg has been elusive. Here, we addressed the role of Bsg in the pathogenesis of LN.

METHODS

Injections of pristane (2,6,10,14-tetramethylpentadecane [TMPD]) were administered to Bsg(-/-) or Bsg(+/+) mice to induce LN. The mice were killed 6 months after being injected, for histologic and biochemical analyses of the kidneys and spleens.

RESULTS

Pristane induced LN more strikingly in Bsg(-/-) mice than in Bsg(+/+) mice, even though humoral autoimmunity was similarly increased in both genotypes. The increased number of Th17, but not Th1, Treg cells, was augmented in Bsg(-/-) mice. The expression of IL-17 was also increased in the kidneys of Bsg(-/-) mice, in proportion to LN disease activity. Furthermore, treatment with anti-IL-17 antibody reduced LN disease activity in Bsg(-/-) mice. Complementary to these phenotypes of Bsg(-/-) mice, Bsg expression was enhanced in activated CD4+ T cells in vivo and in vitro. Bsg deficiency selectively augmented in vitro differentiation of naive CD4+ T cells to Th17 cells and STAT-3 phosphorylation during this differentiation. Moreover, STAT-3 phosphorylation was suppressed by crosslinking of Bsg with its antibody.

CONCLUSION

Bsg plays an indispensable role in Th17 cell differentiation as a negative regulator by suppressing the IL-6/STAT-3 pathway.

Novel insights into the role of immune cells in skin and inducible skin-associated lymphoid tissue (iSALT)

The skin is equipped with serial barriers that provide rapid and efficient protection against external intruders. Beneath the epidermal physical barriers of the stratum corneum and the tight junctions, the integrated immune systems in both the epidermis and the dermis act in a coordinated manner to protect the host. This “immunological” barrier is composed of various cells, including skin-resident cells, such as keratinocytes, dendritic cells, tissue-resident macrophages, resident memory T cells, mast cells, and innate lymphoid cells. Additionally, infiltrating memory T cells, monocytes, neutrophils, basophils, and eosinophils are recruited in support of the host immunity.

In addition to discussing the role of each of these cellular populations, we describe the concept of skin associated lymphoid tissue (SALT), which reminds us that the skin is an important component of the lymphatic system. We further describe the newly discovered phenomenon of multiple cell gathering under skin inflammation, which can be referred to as inducible SALT (iSALT). iSALT contributes to our understanding of SALT by highlighting the importance of direct cell-cell interaction in skin immunity.

Shifted T Helper Cell Polarization in a Murine Staphylococcus aureus Mastitis Model

Mastitis, one of the most costly diseases in dairy ruminants, is an inflammation of the mammary gland caused by pathogenic infection. The mechanisms of adaptive immunity against pathogens in mastitis have not been fully elucidated. To investigate T helper cell-mediated adaptive immune responses, we established a mastitis model by challenge with an inoculum of 4 × 106 colony-forming units of Staphylococcus aureus in the mammary gland of lactating mice, followed by quantification of bacterial burden and histological analysis. The development of mastitis was accompanied by a significant increase in both Th17 and Th1 cells in the mammary gland. Moreover, the relative expression of genes encoding cytokines and transcription factors involved in the differentiation and function of these T helper cells, including Il17, Rorc, Tgfb, Il1b, Il23, Ifng, Tbx21, and Il12, was greatly elevated in the infected mammary gland. IL-17 is essential for neutrophil recruitment to infected mammary gland via CXC chemokines, whereas the excessive IL-17 production contributes to tissue damage in mastitis. In addition, a shift in T helper cell polarization toward Th2 and Treg cells was observed 5 days post-infection, and the mRNA expression of the anti-inflammatory cytokine Il10 was markedly increased at day 7 post-infection. These results indicate that immune clearance of Staphylococcus aureus in mastitis is facilitated by the enrichment of Th17, Th1 and Th2 cells in the mammary gland mediated by pro-inflammatory cytokine production, which is tightly regulated by Treg cells and the anti-inflammatory cytokine IL-10.

Toll-like receptors (TLR) 2 and 4 expression of keratinocytes from patients with localized and disseminated dermatophytosis

There are few studies on the role of innate immune response in dermatophytosis. An investigation was conducted to define the involvement of Toll-Like Receptors (TLRs) 2 and 4 in localized (LD) and disseminated (DD) dermatophytosis due to T. rubrum. Fifteen newly diagnosed patients, eight patients with LD and seven with DD, defined by involvement of at least three body segments were used in this study. Controls comprised twenty skin samples from healthy individuals undergoing plastic surgery. TLR2 and TLR4 were quantified in skin lesions by immunohistochemistry. A reduced expression of TLR4 in the lower and upper epidermis of both LD and DD patients was found compared to controls; TLR2 expression was preserved in the upper and lower epidermis of all three groups. As TLR4 signaling induces the production of inflammatory cytokines and neutrophils recruitment, its reduced expression likely contributed to the lack of resolution of the infection and the consequent chronic nature of the dermatophytosis. As TLR2 expression acts to limit the inflammatory process and preserves the epidermal structure, its preserved expression may also contribute to the persistent infection and limited inflammation that are characteristic of dermatophytic infections.

Pathogenic Transdifferentiation of Th17 Cells Contribute to Perpetuation of Rheumatoid Arthritis during Anti-TNF Treatment

T-helper cells producing interleukin (IL)-17A and IL-17F cytokines (Th17 cells) are considered the source of autoimmunity in rheumatoid arthritis (RA). In this study, we characterized specific pathogenic features of Th17 cells in RA. By using nano-string technology, we analyzed transcription of 419 genes in the peripheral blood CCR6(+)CXCR3(-) CD4(+) cells of 14 RA patients and 6 healthy controls and identified 109 genes discriminating Th17 cells of RA patients from the controls. Th17 cells of RA patients had an aggressive pathogenic profile and in addition to signature cytokines IL-17, IL-23 and IL-21, and transcriptional regulators RAR-related orphan receptor gamma of T cells (RORγt) and Janus kinase 2 (JAK2), they produced high levels of IL-23R, C-C chemokine ligand type 20 (CCL20), granulocyte-monocyte colony-stimulating factor (GM-CSF ) and transcription factor Tbet required for synovial homing. We showed that Th17 cells are enriched with Helios-producing Foxp3- and IL2RA-deficient cells, indicating altered regulatory profile. The follicular T-helper (Tfh) cells presented a functional profile of adaptor molecules, transcriptional regulator Bcl-6 and B-cell activating cytokines IL-21, IL-31 and leukemia inhibitory factor (LIF ). We observed that anti-tumor necrosis factor (TNF) treatment had a limited effect on the transcription signature of Th17 cells. Patients in remission retained the machinery of receptors (IL-23R and IL-1R1), proinflammatory cytokines (IL-17F, IL-23, IL-21 and TNF ) and adaptor molecules (C-X-C chemokine receptor 5 [CXCR5] and cytotoxic T-lymphocyte-associated protein 4 [CTLA-4]), essential for efficient transdifferentiation and accumulation of Th17 cells. This study convincingly shows that the peripheral blood CCR6(+)CXCR3(-) CD4(+) cells of RA patients harbor pathogenic subsets of Th17 and Tfh cells, which may transdifferentiate from Tregs and contribute to perpetuation of the disease.

Perinatal chronic hypoxia induces cortical inflammation, hypomyelination, and peripheral myelin-specific T cell autoreactivity

pCH is an important risk factor for brain injury and long-term morbidity in children, occurring during the developmental stages of neurogenesis, neuronal migration, and myelination. We show that a rodent model of pCH results in an early decrease in mature myelin. Although pCH does increase progenitor oligodendrocytes in the developing brain, BrdU labeling revealed a loss in dividing progenitor oligodendrocytes, indicating a defect in mature cell replacement and myelinogenesis. Mice continued to exhibited hypomyelination, concomitant with long-term impairment of motor function, weeks after cessation of pCH. The implication of a novel neuroimmunologic interplay, pCH also induced a significant egress of infiltrating CD4 T cells into the developing brain. This pCH-mediated neuroinflammation included oligodendrocyte-directed autoimmunity, with an increase in peripheral myelin-specific CD4 T cells. Thus, both the loss of available, mature, myelin-producing glial cells and an active increase in autoreactive, myelin-specific CD4 T cell infiltration into pCH brains may contribute to early pCH-induced hypomyelination in the developing CNS. The elucidation of potential mechanisms of hypoxia-driven autoimmunity will expand our understanding of the neuroimmune axis during perinatal CNS disease states that may contribute to long-term functional disability.

PLZF regulates CCR6 and is critical for the acquisition and maintenance of the Th17 phenotype in human cells

Th17 cells, which express the chemokine receptor CCR6, are implicated in many immune-mediated disorders, such as psoriasis and multiple sclerosis. We found that expression levels of CCR6 on human effector/memory CD4(+) T cells reflect a continuum of Th17 differentiation. By evaluating the transcriptome in cells with increasing CCR6, we detected progressive upregulation of ZBTB16, which encodes the broad complex, tramtrack, bric-à-brac-zinc finger transcription factor promyelocytic leukemia zinc finger protein (PLZF). Using chromatin immunoprecipitation for modified histones, p300, and PLZF, we identified enhancer-like sites at -9/-10 and -13/-14 kb from the upstream transcription start site of CCR6 that bind PLZF in CCR6(+) cells. For Th cells from adult blood, both in the CCR6(+) memory population and in naive cells activated ex vivo, knockdown of ZBTB16 downregulated CCR6 and other Th17-associated genes. ZBTB16 and RORC (which encodes the "master regulator" RORγt) cross-regulate each other, and PLZF binds at the RORC promoter in CCR6(+) cells. In naive Th cells from cord blood, ZBTB16 expression was confined to CD161(+) cells, which are Th17 cell precursors. ZBTB16 was not expressed in mouse Th17 cells, and Th17 cells could be made from luxoid mice, which harbor an inactivating mutation in Zbtb16. These studies demonstrate a role for PLZF as an activator of transcription important both for Th17 differentiation and the maintenance of the Th17 phenotype in human cells, expand the role of PLZF as a critical regulator in the human adaptive immune system, and identify a novel, essential element in a regulatory network that is of significant therapeutic interest.

Estradiol inhibits Th17 cell differentiation through inhibition of RORγT transcription by recruiting the ERα/REA complex to estrogen response elements of the RORγT promoter

The symptoms of vaginal candidiasis exacerbate in the second half of the menstrual cycle in premenopausal women when the serum estradiol level is elevated. Estradiol has been shown to inhibit Th17 differentiation and production of antifungal IL-17 cytokines. However, little is known about the mechanisms. In the present study, we used mouse splenocytes and found that estradiol inhibited Th17 differentiation through downregulation of Rorγt mRNA and protein expression. Estradiol activated estrogen receptor (ER)α to recruit repressor of estrogen receptor activity (REA) and form the ERα/REA complex. This complex bound to three estrogen response element (ERE) half-sites on the Rorγt promoter region to suppress Rorγt expression. Estradiol induced Rea mRNA and protein expression in mouse splenocytes. Using Rea small interfering RNA to knock down Rea expression enhanced Rorγt expression and Th17 differentiation. Alternatively, histone deacetylase 1 and 2 bound to the three ERE half-sites, independent of estradiol. Histone deacetylase inhibitor MS-275 dose- and time-dependently increased Rorγt expression and subsequently enhanced Th17 differentiation. In 15 healthy premenopausal women, high serum estradiol levels are correlated with low RORγT mRNA levels and high REA mRNA levels in the vaginal lavage. These results demonstrate that estradiol upregulates REA expression and recruits REA via ERα to the EREs on the RORγT promoter region, thus inhibiting RORγT expression and Th17 differentiation. This study suggests that the estradiol/ERα/REA axis may be a feasible target in the management of recurrent vaginal candidiasis.