Functional Plasticity of Th17 Cells: Implications in Gastrointestinal Tract Function

Sirtuin2 suppresses the polarization of regulatory T cells toward T helper 17 cells through repressing the expression of signal transducer and activator of transcription 3 in a mouse colitis model

INTRODUCTION

Regulatory T cells (Tregs) play an important role in inflammatory bowel diseases (IBDs) through modulating intestinal inflammation. However, the factors affecting Treg function and plasticity during IBD progression are not thoroughly disclosed. The current study aims to reveal new molecular mechanisms affecting Treg plasticity.

METHODS

A mouse strain, in which tdTomato and enhanced green fluorescent protein were under the control of the Foxp3 promoter and Il17a promoter, was established and subjected to colitis induction with dextran sulfate sodium. The existence of Tregs and IL-17-expressing Tregs (i.e., Treg/T helper 17 [Th17] cells) were observed and sorted from the spleen, mesenteric lymph nodes, and lamina propria by flow cytometry, followed by measuring Sirtuin2 (Sirt2) expression using quantitative reverse transcription polymerase chain reaction and Immunoblotting. Lentivirus-induced Sirt2 silencing was applied to determine the impact of Sirt2 on Treg polarization to Treg/Th17 cells and even Th17 cells. The effect of Sirt2 on Stat3 was analyzed by flow cytometry and immunoblotting.

RESULTS

Sirt2 was highly expressed in lamina propria Tregs and it moderately suppressed Foxp3 expression as well as the immunosuppressive function of Tregs. Surprisingly, lentivirus-mediated Sirt2 silencing promoted the generation of Treg/Th17 cells out of Tregs. Sirt2 silencing also enhanced the generation of Th17 cells out of Tregs under the Th17 induction condition. Furthermore, Sirt2 inhibited Th17 induction by suppressing the protein level of the signal transducer and activator of transcription 3.

CONCLUSION

Sirt2 suppresses Treg function but also inhibits Treg polarization toward Treg/Th17 cells and Th17 cells. The ultimate effect of Sirt2 on colitis might depend on the balance among Tregs, Treg/Th17 cells, and Th17 cells.

Complications after Prostate Cancer Treatment: Pathophysiology and Repair of Post-Radiation Urethral Stricture Disease

Radiation therapy (RT) in the management of pelvic cancers remains a clinical challenge to urologists given the sequelae of urethral stricture disease secondary to fibrosis and vascular insults. The objective of this review is to understand the physiology of radiation-induced stricture disease and to educate urologists in clinical practice regarding future prospective options clinicians have to deal with this condition. The management of post-radiation urethral stricture consists of conservative, endoscopic, and primary reconstructive options. Endoscopic approaches remain an option, but with limited long-term success. Despite concerns with graft take, reconstructive options such as urethroplasties in this population with buccal grafts have shown long-term success rates ranging from 70 to 100%. Robotic reconstruction is augmenting previous options with faster recovery times. Radiation-induced stricture disease is challenging with multiple interventions available, but with successful outcomes demonstrated in various cohorts including urethroplasties with buccal grafts and robotic reconstruction.

Isoalantolactone protects against ethanol-induced gastric ulcer via alleviating inflammation through regulation of PI3K-Akt signaling pathway and Th17 cell differentiation

Gastric ulcer (GU) is one of the most prevalent digestive system diseases in humans, and it has been linked to inflammation. Previous studies have demonstrated the anti-inflammatory potential of isoalantolactone (IAL), a sesquiterpene lactone isolated from Radix Inulae. However, the pharmacological effects of IAL on GU and its mechanism of action are still unclear. Hence, the present study is aimed to investigate the anti-inflammatory potential of IAL on GU. Firstly, we assessed the effect of IAL on ethanol-induced injury of human gastric epithelial cells and the levels of inflammatory cytokines in cell culture supernatants. Then, the anti-inflammatory effects of IAL were confirmed in vivo using zebrafish inflammation models. Furthermore, the mechanism of IAL against GU was preliminarily discussed through network pharmacology and molecular docking studies. Quantitative real-time PCR assays were also used to confirm the mechanism of IAL action. ALB, EGFR, SRC, HSP90AA1, and CASP3 were found for the first time as the key targets of the IAL anti-GU. PI3K-Akt signaling pathway and Th17 cell differentiation were identified to play a crucial role in the anti-GU effects of IAL. In conclusion, we found that IAL has anti-inflammatory effects both in vitro and in vivo, and showed potential protective effects against ethanol-induced GU.

Cornus mas L. Extract Targets the Specific Molecules of the Th17/Treg Developmental Pathway in TNBS-Induced Experimental Colitis in Rats

Given that one of the crucial events in the pathogenesis of inflammatory bowel disease is the loss of homeostasis between Th17 and Treg cells, targeting the specific molecules of the Th17/Treg axis developmental pathway is a promising strategy for inflammatory bowel disease prevention and treatment. The current study aimed to assess the impact of cornelian cherry (Cornus mas L.) extract, rich in iridoids and polyphenols known for their potential anti-inflammatory activity, at two doses (20 or 100 mg/kg) on the crucial factors for Th17/Treg cell differentiation in the course of experimental colitis and compare this action with that of sulfasalazine. This study was conducted on the biobank colon tissue samples collected during the previous original experiment, in which colitis in rats was induced by trinitrobenzenesulfonic acid (TNBS). The levels of IL-6, RORγt, total STAT3, p-STAT3, and Foxp3 were determined by ELISA. The expression of PIAS3 mRNA was quantified by qPCR. Cornelian cherry extract at a dose of 100 mg/kg counteracted the TNBS-induced elevation of IL-6, RORγt, and p-STAT3 levels and a decrease in Foxp3 level and PIAS3 mRNA expression, while given concomitantly with sulfasalazine was more effective than sulfasalazine alone in reversing the TNBS-induced changes in IL-6, RORγt, total STAT3, p-STAT3, Foxp3 levels, and PIAS3 mRNA expression. The beneficial effect of cornelian cherry extract on experimental colitis may be due to its immunomodulatory activity reflected by the influence on factors regulating the Th17/Treg axis.

A 31-plex panel for high-dimensional single-cell analysis of murine preclinical models of solid tumors by imaging mass cytometry

Currently, the study of resistance mechanisms and disease progression in cancer relies on the capacity to analyze tumors as a complex ecosystem of healthy and malignant cells. Therefore, one of the current challenges is to decipher the intra-tumor heterogeneity and especially the spatial distribution and interactions of the different cellular actors within the tumor. Preclinical mouse models are widely used to extend our understanding of the tumor microenvironment (TME). Such models are becoming more sophisticated and allow investigating questions that cannot be addressed in clinical studies. Indeed, besides studying the tumor cell interactions within their environment, mouse models allow evaluating the efficacy of new drugs and delivery approaches, treatment posology, and toxicity. Spatially resolved analyses of the intra-tumor heterogeneity require global approaches to identify and localize a large number of different cell types. For this purpose, imaging mass cytometry (IMC) is a major asset in the field of human immuno-oncology. However, the paucity of validated IMC panels to study TME in pre-clinical mouse models remains a critical obstacle to translational or basic research in oncology. Here, we validated a panel of 31 markers for studying at the single-cell level the TME and the immune landscape for discovering/characterizing cells with complex phenotypes and the interactions shaping the tumor ecosystem in mouse models.

Annexin A1 as a Regulator of Immune Response in Cancer

Annexin A1 is a 37 kDa phospholipid-binding protein that is expressed in many tissues and cell types, including leukocytes, lymphocytes and epithelial cells. Although Annexin A1 has been extensively studied for its anti-inflammatory activity, it has been shown that, in the cancer context, its activity switches from anti-inflammatory to pro-inflammatory. Remarkably, Annexin A1 shows pro-invasive and pro-tumoral properties in several cancers either by eliciting autocrine signaling in cancer cells or by inducing a favorable tumor microenvironment. Indeed, the signaling of the N-terminal peptide of AnxA1 has been described to promote the switching of macrophages to the pro-tumoral M2 phenotype. Moreover, AnxA1 has been described to prevent the induction of antigen-specific cytotoxic T cell response and to play an essential role in the induction of regulatory T lymphocytes. In this way, Annexin A1 inhibits the anti-tumor immunity and supports the formation of an immunosuppressed tumor microenvironment that promotes tumor growth and metastasis. For these reasons, in this review we aim to describe the role of Annexin A1 in the establishment of the tumor microenvironment, focusing on the immunosuppressive and immunomodulatory activities of Annexin A1 and on its interaction with the epidermal growth factor receptor.

Retinoic Acid: A New Old Friend of IL-17A in the Immune Pathogeny of Liver Fibrosis

Despite all the medical advances mortality due to cirrhosis and hepatocellular carcinoma, the end stages of fibrosis, continuously increases. Recent data suggest that liver fibrosis is guided by type 3 inflammation with IL-17A at the top of the line. The storage of vitamin A and its active metabolites, as well as genetics, can influence the development and progression of liver fibrosis and inflammation. Retinoic acid (active metabolite of vitamin A) is able to regulate the differentiation of IL-17A⁺/IL-22–producing cells as well as the expression of profibrotic markers. IL-17A and its pro-fibrotic role in the liver is the most studied, while the interaction and communication between IL-17A, IL-22, and vitamin A–active metabolites has not been investigated. We aim to update what is known about IL-17A, IL-22, and retinoic acid in the pathobiology of liver diseases.

Formulation of a recombinant HIV-1 polytope candidate vaccine with naloxone/alum mixture: induction of multi-cytokine responses with a higher regulatory mechanism

The potency of a vaccine highly depends upon the nature of the adjuvant used. There are a variety of ineffective vaccines, such as HIV-1 vaccine candidates, that need to be optimized with new adjuvant formulations to improve vaccine potency and efficacy. Studies show the potency of naloxone (NLX)/alum mixture in the induction of Th1/Th2 response for vaccine. However, other immunologic patterns inducing by this adjuvant and its immunoregulatory effect is unclear. In this regard, the aim of the present study was to investigate the effect of the NLX/alum mixture, as an adjuvant, on cytokine networks and immunoregulatory activity for an HIV-1 polytope vaccine. BALB/c mice were divided into six groups (n = 6) and immunized subcutaneously with 10 μg of the vaccine formulated with NLX/alum, NLX, alum, and Freund's adjuvants. At the same time, the mice in the control groups received an equal volume of PBS or NLX. The lymphocyte proliferation assay was carried out using the BrdU method. ELISA was used to measure the levels of IFN-γ, IL-2, IL-4, IL-10, IL-12, and IL-17 cytokines, total IgG, as well as IgG1 and IgG2a subtypes in serum samples. Our findings showed that mice receiving the NLX/alum-adjuvanted vaccine exhibited increased antibody levels compared with other groups. In addition, there was a considerable difference in the levels of IgG1, IgG2a, IFN-γ, IL-2, IL-10, IL-12, and IL-17 in mice receiving the NLX/alum-adjuvanted vaccine as compared with other groups. The NLX/alum mixture, as an adjuvant, may have a positive effect on the induction of multi-cytokine responses, as well as the increased level of IL-10, showing its higher immunogenicity with a higher immunoregulatory mechanism.

Retinoid-Related Orphan Receptor RORγt in CD4+ T-Cell-Mediated Intestinal Homeostasis and Inflammation

Retinoic acid-related orphan receptor (ROR)-γt, the master transcription factor of the Th17 subset of CD4⁺ Th cells, is a promising target for treating a host of autoimmune diseases. RORγt plays a vital role in the pathogenesis of inflammatory bowel diseases-Crohn disease and ulcerative colitis-caused by untoward reactivity of the immune system to the components of the intestinal microbiome. The mammalian intestinal tract is a highly complex and compartmentalized organ with specialized functions, and is a privileged site for the generation of both peripherally induced regulatory CD4⁺ T cells (Tregs) and effector Th17 cells. As Th17 cells can be proinflammatory in nature, the equilibrium between effector Th17 and Treg cells is crucial for balancing intestinal homeostasis and inflammation. Recent findings suggest that RORγt, in addition to Th17 cells, is also expressed in peripherally induced, colonic regulatory CD4⁺ T cells. Therefore, RORγt is expressed in both effector and regulatory subsets of CD4⁺ T cells in the intestine. The present review discusses the role of RORγt in cellular and molecular differentiation of Th17 and Treg, and examines how targeting RORγt in inflammatory bowel disease therapy could influence the development of these two diverse subsets of immune cells with opposing functions.

Gastric Cancer Stem Cells Effect on Th17/Treg Balance; A Bench to Beside Perspective

Gastric cancer stem cells (GCSCs), a small population among tumor cells, are responsible for tumor initiation, development, metastasis, and recurrence. They play a crucial role in immune evasion, immunomodulation, and impairment of effector immunity and believed to be emerged to change the balance of the immune system, importantly CD4+ T cells in the chronic inflamed tumor site. However, different subtypes of innate and adaptive immune cells are involved in the formation of the immune system in the tumor microenvironment, we would look at T cells in this study. Tumor microenvironment induces differentiation of CD4+ T cells into different subsets of T cells, mainly suppressive regulatory T cells (Treg), and T helper 17 (Th17) cells, although their exact role in tumor immunity is still under debate depending on tumor types and stages. Counterbalance between Th17 and Treg cells in the gastrointestinal system result in the homeostasis and normal function of the immune system, particularly mucosal immunity. Recent data demonstrated a high infiltration of Th17 and Treg cells into the gastric tumor site and proved that tumor microenvironment might disturb the balance between Th17 and Treg. It is possible to assume an association between activation of CSCs which contribute to metastasis in late stages, and the imbalanced Th17/Treg cells observed in advanced gastric cancer patients. This review intends to clarify the importance of gastric tumor microenvironment specifically CSCs in relation to Th17/Tregs balance firstly and to highlight the relevance of imbalanced Th17/Treg subsets in determining the stages and behavior of the tumor secondly. Finally, the present study suggests a clinical approach looking at the plasticity of T cells with a focus on Th17 as a promising dedicated arm in cancer immunotherapy.

Sodium Chloride Aggravates Arthritis via Th17 Polarization

PURPOSE

Sodium chloride (NaCl) has been proposed as a driving factor in autoimmune diseases through the induction of pathogenic CD4⁺ T helper cells that produce interleukin-17 (Th17 cells). This study investigated the effects of NaCl on inflammatory arthritis in mice and humans.

MATERIALS AND METHODS

Collagen-induced arthritis (CIA) mice were fed a normal or high-salt diet ad libitum, and clinical and histologic features of arthritis were evaluated. The proportion of Th17 cells in the spleens of CIA mice fed a normal or high-salt diet was evaluated by flow cytometry, and the expression of IL-17 in joints and intestines was determined by immunohistochemical staining. We also analyzed the effect of NaCl on Th17 differentiation from peripheral blood monocytes of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and evaluated the contents of sodium and IL-17 in the synovial fluid of RA and OA patients.

RESULTS

NaCl increased murine and human Th17 cell differentiation in a dose-dependent manner. Clinical and histological arthritis was more severe in the high-salt-fed CIA mice, compared to control CIA mice. The proportion of Th17 cells among splenocytes was higher in CIA mice fed a high-salt diet. Expression of synovial and intestinal IL-17 was also higher in high-salt-fed CIA mice. Comparison of synovial fluid between RA patients and OA patients revealed that Na⁺ and IL-17 were more abundant in RA synovial fluid.

CONCLUSION

This study suggests that NaCl can aggravate arthritis by affecting Th17 differentiation. Accordingly, limiting salt intake may be helpful for treating inflammatory arthritis, such as RA.

Regional Specialisation of T Cell Subsets and Apoptosis in the Human Gut Mucosa: Differences Between Ileum and Colon in Healthy Intestine and Inflammatory Bowel Diseases

BACKGROUND AND AIMS

There is very limited information regarding region-specific immunological response in human intestine. We aimed to determine differences in immune compartmentalisation between ileum and colon in healthy and inflamed mucosa.

METHODS

T cell profile and its apoptosis were measured by flow cytometry, Th1, Th17, Treg [CD4(+)CD25(+)FOXP3(+)], double positive [DP, CD3(+)CD4(+)CD8(+)] and double negative T cells [DN, CD3(+)CD4(-)CD8(-)], immunohistochemistry [FOXP3, caspase-3], and real-time polymerase chain reaction [PCR] [IFN-γ, IL-17-A, and FOXP3] on biopsies from different regions of healthy intestine and of intestine in inflammatory bowel diseases.

RESULTS

Healthy colon showed higher percentages of Treg, Th17, and DN, and lower numbers of DP T cells compared with ileum [p < 0.05]. Some but not all region-specific differences were lost in inflammatory conditions. Disease-specific patterns were found: a Th1/Th17 pattern and a Th17 pattern in Crohn's disease and ulcerative colitis respectively, whereas a reduction in Th1/Th17 was found in microscopic colitis. In colonic Crohn's disease and microscopic colitis, DN T cells had a pattern inverse to that of Th1/Th17 (increase in microscopic colitis [p < 0.05] and decrease in Crohn's disease [p < 0.005]). Higher levels of lymphocyte apoptosis were found in healthy colon compared with the ileal counterparts [p = 0.001]. All forms of colonic inflammation presented a dramatic decrease in apoptosis compared with healthy colon. By contrast ileal Crohn's disease showed higher levels of cleaved-Caspase(+) CD3(+) cells.

CONCLUSIONS

Immunological differences exist in healthy gastrointestinal tract. Inflammatory processes overwhelm some location-specific differences, whereas others are maintained. Care has to be taken when analysing immune response in intestinal inflammation, as location-specific differences may be relevant.

Immunological Differences between Lymphocytic and Collagenous Colitis

BACKGROUND

Lymphocytic (LC) and collagenous (CC) colitis are the two major forms of microscopic colitis (MC). The aim of this study was to identify similarities and differences in their mucosal immune characteristics.

METHODS

Colonic biopsies from 15 CC, 8 LC, and 10 healthy controls were collected. Mucosal lymphocytes were assessed by flow cytometry. Tissue gene expression and protein levels were determined by real-time PCR and ELISA, respectively.

RESULTS

LC patients had lower numbers of CD4(+) and double-positive CD4(+)CD8(+)mucosal T lymphocytes, and higher numbers of CD8(+) and CD4(+)TCRγδ(+) mucosal T cells, compared with controls and CC patients. Regulatory Treg (CD4(+)CD25(+)FOXP3(+)) and double-negative (CD3(+)CD4(-)CD8(-)) T cell percentages were higher in both CC and LC compared with controls, coupled with higher levels of the anti-inflammatory IL-10, both at mRNA and protein levels. By contrast, Th1 and Th17 cells were lower in both CC and LC, although gene expression of Th1/Th17 cytokines was higher in both.

CONCLUSION

CC and LC share some regulatory and effector mechanisms, but not others. Higher IL-10 levels and higher Treg and double-negative T cell percentages, found in both CC and LC, could be responsible for the lack of progression of structural damage and the blockade of proinflammatory cytokine production. However, CC and LC are revealed as separate, independent entities, as they show clearly different mucosal lymphocyte profiles, which could be caused by different luminal triggers of the two diseases. Hence, CC and LC are two closely related but independent intestinal disorders.

Anti-inflammatory activity of hydroalcoholic extracts of Lavandula dentata L. and Lavandula stoechas L

ETHNOPHARMACOLOGICAL RELEVANCE

Plants from genus Lavandula have been used as anti-inflammatory drugs in Mediterranean traditional medicine. Nowadays, there is a growing interest for complementary medicine, including herbal remedies, to treat inflammatory bowel disease (IBD).

AIM OF THE STUDY

To test the anti-inflammatory properties of Lavandula dentata and Lavandula stoechas extracts in two inflammatory experimental models: TNBS model of rat colitis and the carrageenan-induced paw edema in mice, in order to mimic the intestinal conditions and the extra-intestinal manifestations of human IBD, respectively.

MATERIAL AND METHODS

The extracts were characterized through the qualitative HPLC analysis. Then, they were assayed in vitro and in vivo. In vitro studies were performed in BMDMs and CMT-93 epithelial cells with different concentrations of the extracts (ranging from 0.1 to 100µg/ml). The extracts were tested in vivo in the TNBS model of rat colitis (10 and 25mg/kg) and in the carrageenan-induced paw edema in mice (10, 25 and 100mg/kg).

RESULTS

L. dentata and L. stoechas extracts displayed immunomodulatory properties in vitro down-regulating different mediators of inflammation like cytokines and nitric oxide. They also showed anti-inflammatory effects in the TNBS model of colitis as evidenced by reduced myeloperoxidase activity and increased total glutathione content, indicating a decrease of neutrophil infiltration and an improvement of the oxidative state. Besides, both extracts modulated the expression of pro-inflammatory cytokines and chemokines, and ameliorated the altered epithelial barrier function. They also displayed anti-inflammatory effects in the carrageenan-induced paw edema in mice, since a significant reduction of the paw thickness was observed. This was associated with a down-regulation of the expression of different inducible enzymes like MMP-9, iNOS and COX-2 and pro-inflammatory cytokines, all involved in the maintenance of the inflammatory condition.

CONCLUSION

L. dentata and L. stoechas extracts showed intestinal anti-inflammatory effect, confirming their potential use as herbal remedies in gastrointestinal disorders. In addition, their anti-inflammatory effect was also observed in other locations, thus suggesting a possible use for the treatment of the extra-intestinal symptoms of IBD.

Pasteurella multocida Toxin Manipulates T Cell Differentiation

Pasteurella multocida causes various diseases in a broad range of wild and domestic animals. Toxigenic strains of the serotypes A and D produce an AB protein toxin named Pasteurella multocida toxin (PMT). PMT constitutively activates the heterotrimeric G protein subunits Gαq, Gα13, and Gαi through deamidation of a glutamine residue, which results in cytoskeletal rearrangements as well as increased proliferation and survival of the host cell. In human monocytes, PMT alters the lipopolysaccharide (LPS)-induced activation toward a phenotype that suppresses T cell activation. Here we describe that the toxin also modulates CD4-positive T helper (Th) cells directly. PMT amplifies the expansion of Th cells through enhanced cell cycle progression and suppression of apoptosis and manipulates the differentiation of Th subclasses through activation of Signal Transducers and Activators of Transcription (STAT) family members and induction of subtype-specific master transcription factors. A large population of toxin-treated T cells is double-positive for Foxp3 and RORγt, the transcription factors expressed by Treg and Th17 cells, respectively. This suggests that these cells could have the potential to turn into Th17 cells or suppressive Treg cells. However, in terms of function, the PMT-differentiated cells behave as inflammatory Th17 cells that produce IL-17 and trigger T cell proliferation.

TH17 predominant T-cell responses in radiation-induced bowel disease are modulated by treatment with adipose-derived mesenchymal stromal cells

Radiation proctitis is an insidious disease associated with substantial morbidity and mortality. It may develop following the treatment of several cancers by radiotherapy when normal colorectal tissues are present in the irradiation field. There is no unified approach for the assessment and treatment of this disease, partly due to insufficient knowledge about the mechanism involved in the development of radiation proctitis. However, unresolved inflammation is hypothesized to have an important role in late side effects. This study aimed to analyse the involvement of specific immunity in colorectal damage developing after localized irradiation, and evaluate the benefit of immunomodulatory mesenchymal stromal cells isolated from adipose tissue (Ad-MSCs) for reduction of late side effects. Our experimental model of colorectal irradiation induced severe colonic mucosal damage and fibrosis that was associated with T-cell infiltration. Immune cell activation was investigated; adoptive transfer of T cells in nude rats showed stronger colonization by T cells isolated from irradiated rats. The predominant role of T cells in late radiation-induced damage and regeneration processes was highlighted by in vivo depletion experiments. Treatments using Ad-MSCs reduced T-cell infiltration in the colon and reduced established colonic damage as measured by histological score, functional circular muscle contractibility, and collagen deposition. Here, we have demonstrated for the first time the predominance of the TH17 population compared to TH1 and TH2 in radiation-induced bowel disease, and that this is reduced after Ad-MSC treatment. Additionally, we demonstrated in vitro that IL17 acts directly on colonic smooth muscle cells to induce expression of pro-inflammatory genes that could participate in the development of radiation-induced injury. Our data demonstrate that the TH17 population is specifically induced during development of radiation-induced side effects in the colon. Moreover, Ad-MSC treatment modulates the TH17 population and reduces the extracellular matrix remodelling process induced following irradiation.