Biology of IL-21 and the IL-21 receptor

IL21R hypomethylation as a biomarker for distinguishing benign and malignant breast tumours

Some benign and malignant breast tumours are similar in pathological morphology, which are difficult to be distinguished in clinical diagnosis. In this study, we intended to explore novel biomarkers for differential diagnosis of benign and malignant breast tumours. Methylation EPIC 850K beadchip and RNA-sequencing were used to analyse 29 tissue samples from patients with early-stage breast cancer (BC) and benign breast tumours for differently methylated and expressed genes. The altered methylation of IL21R was semi-quantitatively validated in an independent study with 566 tissue samples (279 BC vs. 287 benign breast tumours) using mass spectrometry. Binary logistic regression analysis was performed to evaluate the association between IL21R methylation and BC. BC-associated IL21R hypomethylation and overexpression were identified in the discovery round. In the validation round, BC patients presented significant IL21R hypomethylation compared to women with benign breast tumours (ORs ≥1.29 per-10% methylation, p-values ≤ 5.69E-14), and this hypomethylation was even enhanced in BC patients with ER-negative and PR-negative tumours as well as with triple-negative tumours. The methylation of IL21R showed efficient discriminatory power to distinguish benign breast tumours from BC (area under curve (AUC) = 0.88), and especially from ER-negative BC (AUC = 0.95), PR-negative BC (AUC = 0.93) and triple-negative BC (AUC = 0.96). We disclosed significant IL21R hypomethylation in patients with BC compared to women with benign breast tumours, and revealed the somatic change of DNA methylation could be a potential biomarker for molecular pathology of BC.

The role of Interleukin-21 (IL-21) in allergic disorders: Biological insights and regulatory mechanisms

In recent decades, allergic diseases subsequent from an IgE-mediated response to specific allergens have become a progressively public chronic disease worldwide. They have shaped an important medical and socio-economic burden. A significant proportion of allergic disorders are branded via a form 2 immune response relating Th2 cells, type 2 natural lymphoid cells, mast cells and eosinophils. Interleukin-21 (IL-21) is a participant of the type-I cytokine family manufactured through numerous subsets of stimulated CD4+ T cells and uses controlling properties on a diversity of immune cells. Increasingly, experimental sign suggests a character for IL-21 in the pathogenesis of numerous allergic disorders. The purpose of this review is to discuss the biological properties of IL-21 and to summaries current developments in its role in the regulation of allergic disorders.

Peritoneal B1 and B2 cells respond differently to LPS and IL-21 stimulation

Peritoneal B cells can be divided into B1 cells (CD11b+CD19+) and B2 cells (CD11b-CD19+) based on CD11b expression. B1 cells play a crucial role in the innate immune response by producing natural antibodies and cytokines. B2 cells share similar traits with B1 cells, influenced by the peritoneal environment. However, the response of both B1 and B2 cells to the same stimuli in the peritoneum remains uncertain. We isolated peritoneal B1 and B2 cells from mice and assessed differences in Interleukin-10(IL-10) secretion, apoptosis, and surface molecule expression following exposure to LPS and Interleukin-21(IL-21). Our findings indicate that B1 cells are potent IL-10 producers, possessing surface molecules with an IgMhiCD43+CD21low profile, and exhibit a propensity for apoptosis in vitro. Conversely, B2 cells exhibit lower IL-10 production and surface markers characterized as IgMlowCD43-CD21hi, indicative of some resistance to apoptosis. LPS stimulates MAPK phosphorylation in B1 and B2 cells, causing IL-10 production. Furthermore, LPS inhibits peritoneal B2 cell apoptosis by enhancing Bcl-xL expression. Conversely, IL-21 has no impact on IL-10 production in these cells. Nevertheless, impeding STAT3 phosphorylation permits IL-21 to increase IL-10 production in peritoneal B cells. Moreover, IL-21 significantly raises apoptosis levels in these cells, a process independent of STAT3 phosphorylation and possibly linked to reduced Bcl-xL expression. This study elucidates the distinct functional and response profiles of B1 and B2 cells in the peritoneum to stimuli like LPS and IL-21, highlighting their differential roles in immunological responses and B cell diversity.

Genes involved in the cholecystokinin receptor signaling map were differentially expressed in the jejunum of steers with variation in residual feed intake

The jejunum is a critical site for nutrient digestion and absorption, and variation in its ability to take up nutrients within the jejunum is likely to affect feed efficiency. The purpose of this study was to determine differences in gene expression in the jejunum of beef steers divergent for residual feed intake (RFI) in one cohort of steers (Year 1), and to validate those genes in animals from a second study (Year 2). Steers from Year 1 (n = 16) were selected for high and low RFI. Jejunum mucosal tissue was obtained for RNA-seq. Thirty-two genes were differentially expressed (PFDR≤0.15), and five were over-represented in pathways including inflammatory mediator, cholecystokinin receptor (CCKR) signaling, and p38 MAPK pathways. Several differentially expressed genes (ALOX12, ALPI, FABP6, FABP7, FLT1, GSTA2, MEF2B, PDK4, SPP1, and TTF2) have been previously associated with RFI in other studies. Real-time qPCR was used to validate nine differentially expressed genes in the Year 1 steers used for RNA-seq, and in the Year 2 validation cohort. Six genes were validated as differentially expressed (P < 0.1) using RT-qPCR in the Year 1 population. In the Year 2 population, five genes displayed the same direction of expression as the Year 1 population and 3 were differentially expressed (P < 0.1). The CCKR pathway is involved in digestion, appetite control, and regulation of body weight making it a compelling candidate for feed efficiency in cattle, and the validation of these genes in a second population of cattle is suggestive of a role in feed efficiency.

Interleukin-21 receptor signaling promotes metabolic dysfunction-associated steatohepatitis-driven hepatocellular carcinoma by inducing immunosuppressive IgA+ B cells

BACKGROUND

Dysregulation of immune surveillance is tightly linked to the development of metabolic dysfunction-associated steatohepatitis (MASH)-driven hepatocellular carcinoma (HCC); however, its underlying mechanisms remain unclear. Herein, we aimed to determine the role of interleukin-21 receptor (IL-21R) in MASH-driven HCC.

METHODS

The clinical significance of IL-21R was assessed in human HCC specimens using immunohistochemistry staining. Furthermore, the expression of IL-21R in mice was assessed in the STAM model. Thereafter, two different MASH-driven HCC mouse models were applied between IL-21R-deficient mice and wild type controls to explore the role of IL-21R in MASH-driven HCC. To further elucidate the potential mechanisms by which IL-21R affected MASH-driven HCC, whole transcriptome sequencing, flow cytometry and adoptive lymphocyte transfer were performed. Finally, flow cytometry, enzyme-linked immunosorbent assay, immunofluorescent staining, chromatin immunoprecipitation assay and western blotting were conducted to explore the mechanism by which IL-21R induced IgA+ B cells.

RESULTS

HCC patients with high IL-21R expression exhibited poor relapse-free survival, advanced TNM stage and severe steatosis. Additionally, IL-21R was demonstrated to be upregulated in mouse liver tumors. Particularly, ablation of IL-21R impeded MASH-driven hepatocarcinogenesis with dramatically reduction of lipid accumulation. Moreover, cytotoxic CD8+ T lymphocyte activation was enhanced in the absence of IL-21R due to the reduction of immunosuppressive IgA+ B cells. Mechanistically, the IL-21R-STAT1-c-Jun/c-Fos regulatory axis was activated in MASH-driven HCC and thus promoted the transcription of Igha, resulting in the induction of IgA+ B cells.

CONCLUSIONS

IL-21R plays a cancer-promoting role by inducing IgA+ B cells in MASH-driven hepatocarcinogenesis. Targeting IL-21R signaling represents a potential therapeutic strategy for cancer therapy.

Urban indoor gardening enhances immune regulation and diversifies skin microbiota - A placebo-controlled double-blinded intervention study

According to the hygiene and biodiversity hypotheses, frequent exposure to environmental microbiota, especially through soil contact, diversifies commensal microbiota, enhances immune modulation, and ultimately lowers the risk of immune-mediated diseases. Here we test the underlying assumption of the hygiene and biodiversity hypotheses by instructing volunteers to grow edible plants indoors during the winter season when natural exposure to environmental microbiota is low. The one-month randomized, placebo-controlled double-blind trial consisted of two treatments: participants received either microbially diverse growing medium or visually similar but microbially poor growing medium. Skin microbiota and a panel of seven immune markers were analyzed in the beginning of the trial and after one month. The diversity of five bacterial phyla (Bacteroidetes, Planctomycetes, Proteobacteria, Cyanobacteria, and Verrucomicrobia) and one class (Bacteroidia) increased on the skin of participants in the intervention group while no changes were observed in the placebo group. The number of nodes and edges in the co-occurrence networks of the skin bacteria increased on average three times more in the intervention group than in the placebo group. The plasma levels of the immunomodulatory cytokine interleukin 10 (IL-10) increased in the intervention group when compared with the placebo group. A similar trend was observed in the interleukin 17A (IL-17A) levels and in the IL-10:IL-17A ratios. Participants in both groups reported high satisfaction and adherence to the trial. The current study provides evidence in support of the core assumption of the hygiene and biodiversity hypotheses of immune-mediated diseases. Indoor urban gardening offers a meaningful and convenient approach for increasing year-round exposure to environmental microbiota, paving the way for other prophylactic practices that might help prevent immune-mediated diseases.

Therapeutic potential of interleukin-21 in cancer

Interleukin-21 (IL-21) is an immunostimulatory cytokine which belongs to the common gamma-chain family of cytokines. It plays an import role in the development, differentiation, proliferation, and activation of immune cells, in particular T and natural killer (NK) cells. Since its discovery in 2000, IL-21 has been shown to regulate both adaptive and immune responses associates with key role in antiviral and antitumor responses. Recent advances indicate IL-21 as a promising target for cancer treatment and encouraging results were obtained in preclinical studies which investigated the potency of IL-21 alone or in combination with other therapies, including monoclonal antibodies, checkpoint inhibitory molecules, oncolytic virotherapy, and adoptive cell transfer. Furthermore, IL-21 showed antitumor effects in the treatment of patients with advanced cancer, with minimal side effects in several clinical trials. In the present review, we will outline the recent progress in IL-21 research, highlighting the potential of IL-21 based therapy as single agent or in combination with other drugs to enhance cancer treatment efficiency.

ChIP-seq analysis found IL21R, a target gene of GTF2I-the susceptibility gene for primary biliary cholangitis in Chinese Han

AIMS

Aimed to identify a new susceptibility gene associated with primary biliary cholangitis (PBC) in Chinese Han and investigate the possible mechanism of that gene in PBC.

METHODS

A total of 466 PBC and 694 healthy controls (HC) were included in our study, and genotyping GTF2I gene variants by Sequenom. CD19 + B cells were isolated for Chromatin immunoprecipitation sequencing (ChIP-seq). Additionally, MEME-ChIP was utilized to perform searches for known motifs and de novo motif discovery. The GTF2I ChIP-seq of hematopoietic cell line (K562) results were obtained from ENCODE (GSE176987, GSE177691). The Genomic HyperBrowser was used to determine overlap and hierarchal clustering between ours and ENCODE datasets.

RESULTS

The frequency of the rs117026326 variant T allele was significantly higher in PBC patients than that in HC (20.26% compared with 13.89%, Pc = 1.09E-04). Furthermore, we observed an elevated proportion of GTF2I binding site located in the upstream and 5' UTR of genes in PBC in comparison with HC. Additionally, an in-depth analysis of IL21R region revealed that GTF2I might bind to the IL21R promoter to regulate the expression of the IL21R, with four peaks of GTF2I binding sites, including three increased binding sites in upstream, one increased binding site in 5' UTR. Motif analysis by MEME-ChIP uncovered five significant motifs. A significant overlap between our ChIP and GSE176987, GSE17769 were found by the Genomic HyperBroswer.

CONCLUSIONS

Our study confirmed that GTF2I was associated with PBC in Chinese Han. Furthermore, our gene function analysis indicated that IL21R may be the target gene regulated by GTF2I.

PGE2 functions in ovoviviparous teleost black rockfish (Sebastes schlegelii): evolutionary status between parturition and ovulation†

Fish have evolved various reproductive strategies including oviparity, viviparity, and ovoviviparity, which undoubtedly affect the survival of the whole species continuity. As the final step in reproduction, parturition in viviparous vertebrate and ovulation in oviparous teleost seem to share a similar mechanism, when prostaglandins (PGs) act as the trigger to launch the whole process. In the present study, ovoviviparous teleost black rockfish (Sebastes schlegelii) is employed as the research object. Intraperitoneal injection showed that PGE2 (500 μg/kg) could activate the delivery reactions in perinatal black rockfish. RNA-seq data of ovary in perinatal period revealed transcriptional change in cell junction, inflammation, and apoptosis, which is related to mammal parturition and teleost ovulation. Further results proved the positive correlation between ptger EP2 and previous mentioned pathways. Subsequent experiment proved that PGE2 was able to induce the ovulation and spawning in unfertilized individuals, which had a bilayer follicular structure compared to monolayer follicular in perinatal period black rockfish. Both unfertilized and perinatal ovary matrix could response to PGE2 stimulation. In conclusion, the function of PGE2 in activating both parturition and ovulation in a relatively different pathways conserved with viviparity or oviparity provided novel evidence of the evolutionary status of ovoviviparous vertebrates.

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

IL-21 shapes germinal center polarization via light zone B cell selection and cyclin D3 upregulation

Germinal center (GC) dysregulation has been widely reported in the context of autoimmunity. Here, we show that interleukin 21 (IL-21), the archetypal follicular helper T cell (Tfh) cytokine, shapes the scale and polarization of spontaneous chronic autoimmune as well as transient immunization-induced GC. We find that IL-21 receptor deficiency results in smaller GC that are profoundly skewed toward a light zone GC B cell phenotype and that IL-21 plays a key role in selection of light zone GC B cells for entry to the dark zone. Light zone skewing has been previously reported in mice lacking the cell cycle regulator cyclin D3. We demonstrate that IL-21 triggers cyclin D3 upregulation in GC B cells, thereby tuning dark zone inertial cell cycling. Lastly, we identify Foxo1 regulation as a link between IL-21 signaling and GC dark zone formation. These findings reveal new biological roles for IL-21 within GC and have implications for autoimmune settings where IL-21 is overproduced.

Investigation of the anti-inflammatory effects of native potential probiotics as supplementary therapeutic agents in an in-vitro model of inflammation

BACKGROUND

IBD is considered an inflammatory disease with abnormal and exaggerated immune responses. To control the symptoms, different theraputic agents could be used, however, utilizing the agents with the least side effects could be important. Probiotics as beneficial microorganisms are one of the complementory theraputic agents that could be used to modulate inflammatory signaling pathways. In the current study, we aimed to identify the precise molecular effects of potential probiotics on signaling pathways involved in the development of inflammation.

METHODS

A quantitative real-time polymerase chain reaction (qPCR) assay was used to analyze the expression of JAK /STAT (JAK1, JAK2, JAK3, TYK2, STAT1, STAT2, STAT3, STAT4, STAT5 and STAT6) and inflammatory genes (NEMO, TIRAP, IRAK, and RIP) after the HT -29 cell line treatment with the sonicated pathogens and potential probiotics. A cytokine assay was also used to evaluate IL -6 and IL -1β production after potential probiotic treatment.

RESULTS

The potential probiotic cocktail downregulated the JAK genes and TIRAP, IRAK4, NEMO, and RIP genes in the NF-kB pathway compared with cells that were treated with sonicated gram negative pathogens. The expression of STAT genes was different after potential probiotic treatment. The production of IL -6 and IL -1β decreased after potential probiotic treatment.

CONCLUSIONS

Considering the importance of controlling the symptoms of IBD to improve the life quality of the patients, using probiotic could be crucial. In the current study the studied native potential probiotic cocktails showed anti-inflammatory effects via modulation of JAK /STAT and NF-kB signaling pathways. This observation suggests that our native potential probiotics consumption could be useful in reducing intestinal inflammation.

Phorbol-12-myristate-13-acetate is a potent enhancer of B cells with a granzyme B+ regulatory phenotype

Introduction

The infusion of ex-vivo-generated regulatory B cells may represent a promising novel therapeutic approach for a variety of autoimmune and hyperinflammatory conditions including graft-versus-host disease.

Methods

Previously, we developed a protocol for the generation of a novel population of regulatory B cells, which are characterized by secretion of enzymatically active granzyme B (GraB cells). This protocol uses recombinant interleukin 21 (IL-21) and goat-derived F(ab)'2 fragments against the human B cell receptor (anti-BCR). Generally, the use of xenogeneic material for the manufacturing of advanced therapy medicinal products should be avoided to prevent adverse immune reactions as well as potential transmission of so far unknown diseases.

Results

In the present work we demonstrated that phorbol-12-myristate-13-acetate (PMA/TPA), a phorbol ester with a particular analogy to the second messenger diacylglycerol (DAG), is a potent enhancer of IL-21-induced differentiation of pre-activated B cells into GraB cells. The percentage of GraB cells after stimulation of pre-activated B cells with IL-21 and PMA/TPA was not significantly lower compared to stimulation with IL-21 and anti-BCR.

Discussion

Given that PMA/TPA has already undergone encouraging clinical testing in patients with certain haematological diseases, our results suggest that PMA/TPA may be a safe and feasible alternative for ex-vivo manufacturing of GraB cells.

Implications of IL-21 in solid tumor therapy

Cancer, the most deadly disease, is known as a recent dilemma worldwide. Presently different treatments are used for curing cancers, especially solid cancers. Because of the immune-enhancing functions of cytokine, IL-21 as a cytokine may have new possibilities to manipulate the immune system in disease conditions, as it stimulates NK and CTL functions and drives IgG antibody production. Indeed, IL-21 has been revealed to elicit antitumor-immune responses in several tumor models. Combining IL-21 with other agents, which target tumor cells, immune-regulatory circuits, or other immune-enhancing molecules enhances this activity. The exciting breakthrough in the results obtained in pre-clinical situations has led to the early outset of present developing clinical trials in cancer patients. In the paper, we have reviewed the function of IL-21 in solid tumor immunotherapy.

Interleukin-2 family cytokines: An overview of genes, expression, signaling and functional roles in teleost

The interleukin-2 (IL-2) family cytokines include IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, which share γ chain (γc) subunit in receptors. The IL-2 family cytokines have unique biological effects that regulate differentiation, survival and activation of multiple lymphocyte lineages. Deficiency of IL-2 family signaling pathway in mammals prevents CD4⁺ T cells from developing effector functions and CD8⁺ T cells from developing immunological memory. In the present review, we addressed available information from teleost IL-2 family cytokines and discussed implications in teleost immunity. Also, we described and discussed their expression profiles, receptors, signaling transductions and functions. In teleost, IL-2 family has 5 members (IL-2, IL-4/13, IL-7, IL-15, IL-21) without IL-9, and their receptors share a common γc subunit and include other 6 subunits (IL-2Rβ1/2, IL-4Rα1/2, IL-13Rα1/2, IL-7Rα, IL-15Rα, and IL-21Rα1/2). Some paralogues have changes in domain structure and show differential expression, modulation, functions. IL-2 family cytokines constitutively express in many immune associated tissues and are largely induced after pathogenic microbial stimulation. In general, there are relatively conserved functions in the IL-2 family throughout vertebrates, and many of the key IL-2 family members are important in lymphocyte proliferation and differentiation, development, inflammation from fishes to mammals. This review will give an update on the effective information of teleost IL-2 family cytokines. Thus, it will provide a source of reference for other researchers/readers and inspire further interest.

Effects of Xiao Chengqi Formula on Slow Transit Constipation by Assessing Gut Microbiota and Metabolomics Analysis in vitro and in vivo

The Xiao Chengqi (XCQ) formula is a newly constituted traditional Chinese medicine prescription in the treatment of intestinal motility deficiency and is effective in patients with slow transit constipation (STC). XCQ formula was reconstructed based on a "Chengqi" decoction. Astragali Radix, Angelicae Sinensis Radix, and cooked ground Salviae Miltiorrhizae Radix et Rhizoma were added to the prescription to enhance. An STC rat model was constructed and treated with the formula to understand the detailed mechanism by which XCQ promotes intestinal peristalsis. The effects of the XCQ formula on intestinal microflora and metabolic levels and the possible molecular mechanism of its regulation were explored using 16S rDNA sequencing, metabolomics sequencing, and tissue RNA sequencing. The results showed a significant decrease in the abundance of Roseburia spp. in the feces of STC rats, a significant decrease in the content of butyl aminobenzene (BAB) in feces, and an increase in the number of interstitial cells of Cajal (ICC) in the colon of STC rats. Furthermore, in vitro and in vivo experiments revealed that BAB could activate IL-21R on the ICC surface, upregulate the phosphorylation of the downstream molecules STAT3 and ERK, and inhibit loperamide-induced ICC apoptosis. Therefore, the XCQ formula can improve the defecation status of patients with STC by protecting ICC activity, promoting the colonization of Roseburia spp. to promote peristalsis, and increasing the BAB content after metabolism.

Characterization of snakehead (Channa argus) interleukin-21: Involvement in immune defense against two pathogenic bacteria, in leukocyte proliferation, and in activation of JAK-STAT signaling pathway

Interleukin-21 (IL-21), a crucial immune regulatory molecule, belongs to the common γ-chain family of type I cytokines, and exerts pleiotropic effects on multiple immune cell types in mammals. However, the characteristics and functions of fish IL-21 remain unclear. To further investigate the molecular mechanism of IL-21 in teleosts, we first cloned and identified the IL-21 gene (designated shIL-21) of the snakehead (Channa argus). The full-length open reading frame of shIL-21 is 438 bp in length, and encodes a predicted protein of 145 amino acid residues. A sequence analysis showed that shIL-21 has the typical structural characteristics of other IL-21 proteins, containing four α-helices and four conserved cysteine residues. In a phylogenetic analysis, shIL-21 clustered within a subgroup of IL-21 proteins from other teleost species and shared its closest evolutionary relationship with that of Lates calcarifer. The expression analysis showed that shIL-21 was ubiquitously expressed in all the healthy snakehead tissues tested, albeit at different levels. After infection with Nocardia seriolae or Aeromonas schubertii, the relative expression of shIL-21 was mainly upregulated in the head kidney and spleen in vivo. Similarly, after stimulation with the three pathogen analogues lipoteichoic acid, lipopolysaccharides, and polyinosinic-polycytidylic acid, the expression of shIL-21 was also induced in head kidney leukocytes in vitro. A recombinant shIL-21 protein was expressed and purified, and promoted the proliferation of head kidney leukocytes, induced the expression of genes encoding critical signaling molecules in the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathway, including JAK1, JAK3, STAT1, and STAT3, and induced the expression of endogenous shIL-21 and genes encoding several key proinflammatory cytokines (tumor necrosis factor-α, interferon-γ, and IL-1β). Taken together, these preliminary findings suggest that shIL-21 is involved in the immune defense against bacterial infection, in leukocyte proliferation, and in the activation of the JAK-STAT pathway. They thus extend the functional studies of IL-21 in teleosts.

Biomimetic Scaffolds Modulate the Posttraumatic Inflammatory Response in Articular Cartilage Contributing to Enhanced Neoformation of Cartilaginous Tissue In Vivo

Focal chondral lesions of the knee are the most frequent type of trauma in younger patients and are associated with a high risk of developing early posttraumatic osteoarthritis. The only current clinical solutions include microfracture, osteochondral grafting, and autologous chondrocyte implantation. Cartilage tissue engineering based on biomimetic scaffolds has become an appealing strategy to repair cartilage defects. Here, a chondrogenic collagen-chondroitin sulfate scaffold is tested in an orthotopic Lapine in vivo model to understand the beneficial effects of the immunomodulatory biomaterial on the full chondral defect. Using a combination of noninvasive imaging techniques, histological and whole transcriptome analysis, the scaffolds are shown to enhance the formation of cartilaginous tissue and suppression of host cartilage degeneration, while also supporting tissue integration and increased tissue regeneration over a 12 weeks recovery period. The results presented suggest that biomimetic materials could be a clinical solution for cartilage tissue repair, due to their ability to modulate the immune environment in favor of regenerative processes and suppression of cartilage degeneration.

Payload Delivery: Engineering Immune Cells to Disrupt the Tumour Microenvironment

Although chimeric antigen receptor (CAR) T cells have shown impressive clinical success against haematological malignancies such as B cell lymphoma and acute lymphoblastic leukaemia, their efficacy against non-haematological solid malignancies has been largely disappointing. Solid tumours pose many additional challenges for CAR T cells that have severely blunted their potency, including homing to the sites of disease, survival and persistence within the adverse conditions of the tumour microenvironment, and above all, the highly immunosuppressive nature of the tumour milieu. Gene engineering approaches for generating immune cells capable of overcoming these hurdles remain an unmet therapeutic need and ongoing area of research. Recent advances have involved gene constructs for membrane-bound and/or secretable proteins that provide added effector cell function over and above the benefits of classical CAR-mediated cytotoxicity, rendering immune cells not only as direct cytotoxic effectors against tumours, but also as vessels for payload delivery capable of both modulating the tumour microenvironment and orchestrating innate and adaptive anti-tumour immunity. We discuss here the novel concept of engineered immune cells as vessels for payload delivery into the tumour microenvironment, how these cells are better adapted to overcome the challenges faced in a solid tumour, and importantly, the novel gene engineering approaches required to deliver these more complex polycistronic gene constructs.

Dermatomyositis With Anti-MDA5 Antibodies: Bioclinical Features, Pathogenesis and Emerging Therapies

Anti-MDA5 dermatomyositis is a rare systemic autoimmune disease, historically described in Japanese patients with clinically amyopathic dermatomyositis and life-threatening rapidly progressive interstitial lung disease. Subsequently, the complete clinical spectrum of the disease was enriched by skin, articular and vascular manifestations. Depending on the predominance of these symptoms, three distinct clinical phenotypes with different prognosis are now defined. To date, the only known molecular component shared by the three entities are specific antibodies targeting MDA5, a cytosolic protein essential for antiviral host immune responses. Several biological tools have emerged to detect these antibodies, with drawbacks and limitations for each of them. However, the identification of this highly specific serological marker of the disease raises the question of its role in the pathogenesis. Although current knowledge on the pathogenic mechanisms that take place in the disease are still in their enfancy, several lines of evidence support a central role of interferon-mediated vasculopathy in the development of skin and lung lesions, as well as a possible pathogenic involvement of anti-MDA5 antibodies. Here, we review the clinical and biological evidences in favor of these hypothesis, and we discuss the contribution of emerging therapies that shed some light on the pathogenesis of the disease.

WSB1 and IL21R Genetic Variants Are Involved in Th2 Immune Responses to Ascaris lumbricoides

Genetic and epigenetic factors are considered to be critical for host-parasite interactions. There are limited data on the role of such factors during human infections with Ascaris lumbricoides. Here, we describe the potential role of genetic factors as determinants of the Th2 immune response to A. lumbricoides in Brazilian children. Stool samples were collected from the children to detect A. lumbricoides by microscopy and peripheral blood leukocytes (PBLs) were cultured in whole blood cultures for detection of cytokines (IL-5, IL-10, and IL-13) in vitro. Levels of anti-A. lumbricoides IgE and IgG4 were measured in plasma. DNA was extracted from PBLs and genotyped using Illumina 2.5 Human Omni Beadchip. Candidate genes associated with A. lumbricoides responses were identified and SNVs in these selected genes associated with the Th2 immune response to A. lumbricoides. Haplotype, gene expression, and epigenetic analyses were done to identify potential associations with Th2 immune responses. GWAS on samples from 1,189 children identified WSB1 as a candidate gene, and IL-21R was selected as a biologically relevant linked gene for further analysis. Variants in WSB1 and IL21R were associated with markers of Th2 immune responses: increased A. lumbricoides-specific IgE and IL-5/IL-13 by PBLs from infected compared to uninfected individuals. In infected children, WSB1 but not IL21R gene expression was suppressed and increased methylation was observed in the WSB1 promoter region. This is the first study to show an association between genetic variants in WSB1 and IL21R and Th2 immune responses during A. lumbricoides infections in children. WSB1/IL21R pathways could provide a potential target for the treatment of Th2-mediated diseases.

Th17 Cells in Inflammatory Bowel Disease: Cytokines, Plasticity, and Therapies

Autoimmune diseases (such as rheumatoid arthritis, asthma, autoimmune bowel disease) are a complex disease. Improper activation of the immune system or imbalance of immune cells can cause the immune system to transform into a proinflammatory state, leading to autoimmune pathological damage. Recent studies have shown that autoimmune diseases are closely related to CD4+ T helper cells (Th). The original CD4 T cells will differentiate into different T helper (Th) subgroups after activation. According to their cytokines, the types of Th cells are different to produce lineage-specific cytokines, which play a role in autoimmune homeostasis. When Th differentiation and its cytokines are not regulated, it will induce autoimmune inflammation. Autoimmune bowel disease (IBD) is an autoimmune disease of unknown cause. Current research shows that its pathogenesis is closely related to Th17 cells. This article reviews the role and plasticity of the upstream and downstream cytokines and signaling pathways of Th17 cells in the occurrence and development of autoimmune bowel disease and summarizes the new progress of IBD immunotherapy.

Splicing variants of grass carp (Ctenopharyngodon idellus) IL-21: Functions in IgM+ B cell proliferation and IgM secretion

In mammals, interleukin 21 (IL-21) is a type I four-helical bundle cytokine produced by activated T cells that has pleiotropic functions on immune cells. Although IL-21 has been discovered in fish, the splicing variants of this cytokine and their functions on B cells are unclear. In this study, based on the original transcript of grass carp IL-21 (named gcIL-21sv1 in this study), two alternative splicing variants, named gcIL-21sv2 and gcIL-21sv3, were cloned and characterized. The protein sequences of gcIL-21sv1 and gcIL-21sv2 consist of four α-helixes, and only the six amino acid residues at the C-terminal are different. Unlike gcIL-21sv1 and gcIL-21sv2, gcIL-21sv3 lacks the C-terminal region. The expression analysis showed that gcIL-21sv1, gcIL-21sv2, and gcIL-21sv3 were constitutively expressed in all the tested tissues, and their expression could be significantly up-regulated by LPS and Poly (I:C) in head kidney leukocytes (HKLs), with the fold change of gcIL-21sv1 being higher than that of gcIL-21sv2 and gcIL-21sv3. Recombinant gcIL-21sv1 and gcIL-21sv2, but not gcIL-21sv3, could induce the proliferation of IgM⁺ B cells and the secretion of IgM, with the activity of gcIL-21sv1 being stronger than that of gcIL-21sv2, indicating that the C-terminal region plays important roles in the function of gcIL-21. Taken together, this study found that, like IL-21 in human and mouse, IL-21 splicing variants also exist in fish, and the regulatory activities of these variants in humoral immunity are differ, suggesting that grass carp may balance the immune response mediated by IL-21 through alternative splicing.

Membrane IgM+ plasma cells in grass carp (Ctenopharyngodon idella): Insights into the conserved evolution of IgM+ plasma cells in vertebrates

Teleost fish are the most primitive bony vertebrates that contain B cells; thus, comparative analysis of teleost naïve/mature B cells and plasma cells can provide helpful evidence for understanding the evolution paradigms of these two B-cell subpopulations in vertebrates. In this study, we developed monoclonal antibody against grass carp IgM and identified two different IgM⁺ cell subsets: IgM⁺ lymphocytes (Lym), resembling naïve/mature B cells, and IgM⁺ myeloid cells (Mye), resembling plasma cells. Like plasma cells in mammals, the size of IgM⁺ Mye is significantly larger than that of IgM⁺ Lym, as revealed by flow cytometric analysis and transmission electron microscopy. The IgM⁺ Mye were further verified as plasma cells because they showed gene expression patterns similar with those of human plasma cells and a great capacity to secrete IgM. Like mammalian IgM⁺ and IgA⁺ plasma cells, not IgG⁺ plasma cells, grass carp IgM⁺ Mye also expressed membrane immunoglobulins, a feature conserved in IgM⁺ plasma cells in vertebrates. Furthermore, recombinant CD40L or IL-21 alone could induce the plasma cell generation and IgM secretion, while the combination of CD40L and IL-21 had greater effect on IgM secretion, but not on plasma cell generation. This study fills an important gap in the knowledge of plasma cells in teleost fish and provides critical insights into the conserved evolution of IgM⁺ plasma cells in vertebrates.

Characterization and bioactivity of grass carp (Ctenopharyngodon idella) interleukin-21: Inducible production and involvement in inflammatory regulation

In mammals, interleukin 21 (IL-21) is a broad pleiotropic cytokine that plays critical roles in the development of several inflammatory and autoimmune diseases. In fish, functional information of Il-21 is limited, and its role in immune response is largely unknown. In the present study, we cloned a coding sequence of grass carp (Ctenopharyngodon idella) il21 gene (gcil21). To characterize the release patterns and biological activity of gcIl-21, we prepared recombinant gcIl-21 (rgcIl-21) and obtained the polyclonal antibody with gcIl-21 specificity. Western blotting analysis showed that in grass carp head kidney leukocytes (HKLs), gcIl-21 was undetected in culture supernatant of untreated cells but drastically induced by heat-killed Aeromonas hydrophila (A. hydrophila), uncovering the release features of gcIl-21 and its possible involvement in immune response. Subsequent functional experiments revealed that rgcIl-21 did not affect the mRNA expression of grass carp il1b and tgfb, but induced a strong expression of grass carp il10, and to a lesser extent of grass carp tnfa in HKLs, suggesting a dominant effect of gcIl-21 in modulating Il-10 signaling as seen in rainbow trout and mammals. Furthermore, in vivo studies showed that intraperitoneal injection of rgcIl-21 was able to increase the survival rate of grass carp infected with live A. hydrophila, and reduce the pathological responses caused by the same pathogenic bacteria in head kidney and intestine. Taken together, these results for the first time revealed the close relationship of fish Il-21 production and function with inflammatory responses, and highlighted its anti-bacterial and anti-inflammatory ability, thereby providing a new insight into host defense mechanisms in fish.

Clinico-Biological Implications of Modified Levels of Cytokines in Chronic Lymphocytic Leukemia: A Possible Therapeutic Role

B-cell chronic lymphocytic leukemia (B-CLL) is the main cause of mortality among hematologic diseases in Western nations. B-CLL is correlated with an intense alteration of the immune system. The altered functions of innate immune elements and adaptive immune factors are interconnected in B-CLL and are decisive for its onset, evolution, and therapeutic response. Modifications in the cytokine balance could support the growth of the leukemic clone via a modulation of cellular proliferation and apoptosis, as some cytokines have been reported to be able to affect the life of B-CLL cells in vivo. In this review, we will examine the role played by cytokines in the cellular dynamics of B-CLL patients, interpret the contradictions sometimes present in the literature regarding their action, and evaluate the possibility of manipulating their production in order to intervene in the natural history of the disease.

Germinal center B cell initiation, GC maturation, and the coevolution of its stromal cell niches

Throughout the developing GC response, B cell survival and fate choices made at the single cell level are dependent on signals received largely through interactions with other cells, often with cognate T cells. The type of signals that a given B cell can encounter is dictated by its location within tissue microarchitecture. The focus of this review is on the initiation and evolution of the GC response at the earliest time points. Here, we review the key factors influencing the progression of GC B cell differentiation that are both stage and context dependent. Finally, we describe the coevolution of niches within and surrounding the GC that influence the outcome of the GC response.

Interleukin 21 Reinvigorates the Antiviral Activity of Hepatitis B Virus (HBV)-Specific CD8+ T Cells in Chronic HBV Infection

BACKGROUND

Strategies that target functional recovery of exhausted hepatitis B virus (HBV)-specific CD8+ T cells are beneficial for viral control, but the potential for interleukin 21 (IL-21) to rescue CD8+ T-cell function is not well understood.

METHODS

We investigated the effect of IL-21 on CD8+ T-cell responses by phenotypic and functional analysis of samples from patients with chronic HBV infection and a mouse model with HBV expression.

RESULTS

IL-21 promoted the proliferative capacity of HBV-specific CD8+ T cells and down-regulated expression of the inhibitory receptors programmed death 1 and T-cell immunoglobulin domain and mucin domain 3. Additionally, IL-21 boosted the production of interferon-γ, granzyme B, and CD107a in HBV-specific CD8+ T cells and enhanced the cytolytic activity of CD8+ T cells against HepG2.2.15 cells. Notably, an HBV mouse model established from IL-21 receptor knockout mice showed significantly decreased frequency of HBV-specific CD8+ T cells and increased levels of serum hepatitis B surface antigen (HBsAg). Meanwhile, administration of recombinant mouse IL-21 in an HBV mouse model established from wild-type mice resulted in enhanced functionality of HBV-specific CD8+ T cells and accelerated HBsAg clearance.

CONCLUSIONS

IL-21 enhances the antiviral effect of HBV-specific CD8+ T cells, suggesting that it may contribute to viral clearance in chronic HBV infection.

SKI and SMAD4 are essential for IL-21-induced Th17 differentiation

Th17 cells are essential for the pathogenesis of inflammatory and autoimmune diseases. In the presence of TGF-β, the differentiation of Th17 cells can be induced by inflammatory cytokines, especially IL-6, which is mainly produced by antigen presenting cells (APCs); or IL-21, which is derived from T cells. IL-21 is required for IL-6-induced Th17 cell differentiation. However, the key regulators and underlying mechanisms for IL-21-induced Th17 differentiation is still elusive. Here we show that SMAD4 is a key regulator in IL-21-induced Th17 differentiation. SMAD4 deficient naïve T cells can differentiate into Th17 cells in the absence of TGF-β signaling, and these Th17 cells are pathogenic during EAE. SMAD4 represses Rorc mRNA transcription to constrain IL-21-induced Th17 differentiation in the absence of TGF-β signaling. While in the presence of TGF-β, SMAD4 losses its suppressive ability due to the degradation of SKI. Mutation of Y429A or A432E on SMAD4 disrupts the interaction of SKI from SMAD4 and eliminates SMAD4 mediated suppression of Th17 differentiation. SMAD4 is indispensable for SKI binding to Rorc promoter region to regulate Th17 differentiation. Moreover, activin can induce Th17 differentiation in combination with IL-21, and the process is also subjected to the control of SKI and SMAD4. This study therefore elucidates critical mechanism for IL-21-induced Th17 differentiation to indicate SKI and SMAD4 as potential therapeutic targets for treating autoimmune diseases.

Significant body mass increase by oral administration of a cascade of shIL21-MSTN yeast-based DNA vaccine in mice

Base on the practical of MSTN-specific yeast-based protein vaccine in mice as described previously, this research was designed for developing a better DNA vaccine (a cascade of shIL21-MSTN yeast-based DNA vaccine) than solely MSTN yeast-based DNA vaccine to block the endogenous MSTN in the murine model. We first constructed the target vectors, including CMV-driven MSTN expression vector and a combined shIL21-MSTN vector which containing MSTN expression cassette and shIL21 (short hairpin RNA-IL21) expression cassette. After necessary validation, recombinant yeast vaccines harboring different vectors were well prepared. Subsequently, after 2-month administration, the MSTN-specific immune response was detected with western blots. The commercial ELISA assays indicated that the production of IL21 and IL6 were decreased compared with control groups. More importantly, the MSTN-specific antibody titer was much higher in the shIL21-MSTN group than MSTN group, which was consistent with the western blots result. The most important finding was significant body mass increased after oral administration of these yeast-based DNA vaccines, in which the shIL21-MSTN vaccine is slightly higher than the sole MSTN vaccine in mice. In this study, we confirmed the role of different MSTN-specific yeast-based DNA vaccines on increasing body mass in mice, to provide a good inspiration for livestock breeding through the new type of immunoregulatory method. On the other hand, we also detected the possible modulating role of shIL21 on the dendritic cell-mediated immune function which needs more practical application and deeper exploration.

Transient Expression of Interleukin-21 in the Second Hit of Acute Pancreatitis May Potentiate Immune Paresis in Severe Acute Pancreatitis

OBJECTIVES

Interleukin-21 (IL-21) is a cytokine associated with tissue inflammation, autoimmune and infectious diseases. Organ dysfunction and death can occur in patients with acute pancreatitis (AP) in two distinct clinical phases. Initially, a systemic inflammatory response syndrome may be followed by systemic sepsis from infected pancreatic necrosis, known as the "second hit." The expression and possible role of IL-21 in AP has not been established.

METHODS

Thirty-six patients with mild, moderate, and severe AP (SAP) were enrolled. Peripheral blood samples of patients were drawn on days 7, 9, 11, and 13. Reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were performed to determine the expression and concentration of IL-21.

RESULTS

Interleukin-21 mRNA levels increased significantly at day 9 in severe (P = 0.002) pancreatitis compared with both the mild and control patient groups. At the protein level, IL-21 was elevated in SAP patients compared with those with mild pancreatitis, although this was not significant. Furthermore, day 9 IL-21 was elevated in septic SAP patients and patients with pancreatic necrosis.

CONCLUSIONS

Interleukin-21 is transiently elevated in SAP compared with the mild/moderate group, and hence IL-21 may contribute to the immune imbalance that occurs in AP.

Nonredundant Roles of IL-21 and IL-4 in the Phased Initiation of Germinal Center B Cells and Subsequent Self-Renewal Transitions

We examined the unique contributions of the cytokines IL-21 and IL-4 on germinal center (GC) B cell initiation and subsequent maturation in a murine model system. Similar to other reports, we found T follicular helper cell expression of IL-21 begins prior to T follicular helper cell migration into the B cell follicle and precedes that of IL-4. Consistent with this timing, IL-21 signaling has a greater influence on the perifollicular pre-GC B cell transition to the intrafollicular stage. Notably, Bcl6^hi B cells can form in the combined absence of IL-21R- and STAT6-derived signals; however, these nascent GC B cells cease to proliferate and are more prone to apoptosis. When B cells lack either IL-21R or STAT6, aberrant GCs form atypical centroblasts and centrocytes that differ in their phenotypic maturation and costimulatory molecule expression. Thus, IL-4 and IL-21 play nonredundant roles in the phased progression of GC B cell development that can initiate in the combined absence of these cytokine signals.

Interleukin-21 Induces Short-Lived Effector CD8+ T Cells but Does Not Inhibit Their Exhaustion after Mycobacterium bovis BCG Infection in Mice

Interleukin 21 (IL-21) is a pleiotropic common cytokine receptor γ chain cytokine that promotes the effector functions of NK cells and CD8⁺ T cells and inhibits CD8⁺ T cell exhaustion during chronic infection. We found that the absolute number of short-lived effector CD8⁺ T cells (SLECs) (KLRG1^high CD127^low) decreased significantly in IL-21 receptor-deficient (IL-21R^-/-) mice during Mycobacterium bovis bacillus Calmette-Guérin (BCG) infection. Early effector CD8⁺ T cells (EECs) (KLRG1^low CD127^low) were normally generated in IL-21R^-/- mice after infection. Exhausted CD8⁺ T cells (PD-1^high KLRG1^low) were also normally generated in IL-21R^-/- mice after infection. Mixed bone marrow (BM) chimera and transfer experiments showed that IL-21R on CD8⁺ T cells was essential for the proliferation of EECs, allowing them to differentiate into SLECs after BCG infection. On the other hand, the number of SLECs increased significantly after infection with recombinant BCG (rBCG) that secreted an antigen 85B (Ag85B)-IL-21 fusion protein (rBCG-Ag85B-IL-21), but the number of exhausted CD8⁺ T cells did not change after rBCG-Ag85B-IL-21 infection. These results suggest that IL-21 signaling drives the differentiation of SLECs from EECs but does not inhibit the exhaustion of CD8⁺ T cells following BCG infection in mice.

Augmentation of the expression of the eotaxin receptor on duodenal neutrophils by IL-21

Inflammation can occur via different mechanisms, such as via acute and chronic responses, on numerous occasions and function accordingly through various roles. There are more than five subsets of neutrophils; neutrophilic heterogeneity is modulated by the inflammatory condition. To understand the characteristics of inflammation, identification of atypical neutrophils is important. In this study, we found that the expression of eotaxin receptor (CD193) on atypical neutrophils in the duodenum is augmented in IL-21 isoform transgenic (Tg) mice. In a series of studies, we have established a Tg mouse strain to further investigate the functions of IL-21 in vivo. Interestingly, Tg mice immunized with ovalbumin (OVA) were more sensitive to OVA-induced systemic anaphylaxis as compared with wild type mice with duodenal and splenic gross congestion. Further analysis conducted in the duodenum of Tg mice revealed that only the number of neutrophils migrating into the duodenum was significantly increased prior to immunization. Previous studies have shown that the gastrointestinal compartment and the spleen constantly produce eotaxin, which regulates basal levels of tissue eosinophils. Therefore, we analyzed CD193 expression on neutrophils and eosinophils. As expected, its expression by duodenal neutrophils was upregulated in Tg mice. Furthermore, the addition of IL-21 into bone marrow cell culture increased the number of CD193⁺ neutrophils, which easily migrated into the duodenum. These observations suggested that CD193⁺ neutrophils increase in number under inflammatory conditions due to chronic IL-21 production.

Comprehensive cytokine profiling provides evidence for a multi-lineage Th responses in Guillain Barré Syndrome

Guillain Barré Syndrome (GBS) is one of the commonest acquired immune-mediated neuropathies, often preceded by infections. Although cellular immune responses are shown to substantially account for the pathophysiology of GBS, the precise mechanistic basis of risk and disease course remains enigmatic till date. Cytokines are best known for their abilities to drive cellular immunity and inflammation through their co-ordinated actions. Data obtained from clinical and animal model studies suggest important implications of some of the cytokines in the progression and recovery of GBS. However, these studies were performed on few cytokines and small set of GBS patients, thereby lacking a complete understanding of the patterns of association of cytokines representing Th1, Th2, and Th17 responses with GBS. We studied 65 well-characterized GBS patients and 73 age- and sex-matched healthy controls. A panel of 15 cytokines representing Th1, Th2 and Th17 pathways was assayed using Multiplex Suspension Array platform. Plasma levels of five cytokines were found to be altered in GBS patients compared to healthy control subjects: (i) IL-1β exhibited reduced levels, and (ii) IFN-γ, IL-4, IL-21 and IL-33 were elevated in GBS patients. The most important finding of this study was up-regulated expression of IL-21 and IL-33 in patients with GBS. Given the role of IL-33 as an alarmin, the elevated level of this cytokine provides important indication about a much broader role of cytokines in GBS. This study also provides evidence towards a multi-lineage Th cells (Th1, Th2 and Th17) associated cytokine responses in the pathophysiology of GBS.

IL-17 and related cytokines involved in systemic sclerosis: Perspectives

Systemic sclerosis (SSc) is a multisystemic, complex, and rare disease of connective tissue, with high morbidity and mortality, and without specific treatment. The disease is characterized by three main principles: vascular disease, autoantibody production and inflammation, and fibrosis. Since it is well defined that SSc is characterized by elevated production of TGF-β, IL-6, and IL-1, all of them cytokines related to Th17 differentiation, the hypothesis is that this disease may be strongly related to a polarization of the immune response towards the Th17 pathway. Considering the importance of a better understanding of the pathophysiology of Th17 pathway in SSc, this article aims to propose an update for a better understanding of current knowledge on main cytokines secreted by the Th17 cells (IL-17 A, IL-21, and IL-22) and the future prospects in the current disease.

IL-23 Activated γδ T Cells Affect Th17 Cells and Regulatory T Cells by Secreting IL-21 in Children with Primary Nephrotic Syndrome

This study (1) analysed the percentage of γδ T cells, γδ T cell subsets, Th17 cells and regulatory T cells (Treg cells) and (2) determined the role of IL-23 in primary nephrotic syndrome (PNS) patients with active disease and in remission. Eighty-four patients with PNS and 51 healthy age-matched controls were included in this study. The percentage of γδ T cells, γδ T cell subsets, Th17 cells and Treg cells in peripheral blood mononuclear cells (PBMCs) were analysed by fluorescence-activated cell sorting. PMBCs from PNS patients with active disease were cultured in the presence of IL-23, IL-23 and an IL-23 antagonist, or IL23 and an anti-IL-21 monoclonal antibody (mAb). The percentage of γδ T cells, IL-23R⁺ γδ T cells and IL-17⁺ γδ T cells were significantly increased in PNS patients with active disease. There was a positive correlation between the percentage of γδ T cells, IL-23R⁺ γδ T cells, IL-17⁺ γδ T cells and the Th17/Treg ratio. IL-23 increased the percentage of γδ T cells and Th17 cells and decreased the percentage of Treg cells in PBMCs isolated from PNS patients with active disease. Anti-IL-21 mAb reduced the percentage of γδ T cells and Th17 cells, but increased the percentage of Treg cells. γδ T cells, IL-17⁺ γδ T cells and IL-23R⁺ γδ T cells may be involved in the pathogenesis of paediatric PNS by modulating the balance of Th17/Treg cells. γδ T cells may cause an imbalance in Th17/Treg cells by secreting IL-21 in the presence of IL-23.

T follicular helper and TH2 cells in allergic responses

IL-4 is a cytokine commonly secreted by T_H2 and follicular helper T (T_FH) cells after antigenic sensitization. T_H2 cells have been thought to be the major contributor of B cell help as a source of IL-4 responsible for class switch recombination to Immunoglobulin G1 (IgG1) and Immunoglobulin E (IgE). Importantly, there are some differences in transcriptional regulation between these two T cell subsets. The IL-4 production by T_H2 and T_FH cells is distinctively regulated by two pathways, GATA-3-mediated Il4-HS2 enhancer and Notch mediated Il4-CNS-2 enhancer. IgE and IgG1 antibody responses are mainly controlled by IL-4-secreting T_FH cells, but not by T_H2 cells. In this review, we discuss the role of T_H2 and T_FH cells in IgE production and allergic responses.

Diminished plasma levels of common γ-chain cytokines in pulmonary tuberculosis and reversal following treatment

Background

The immune response to tuberculosis (TB) is T cell dependent. T cells are the major facilitators of protection and effector functions with CD4⁺ T cells being the most important players, followed by CD8⁺ T cells. The common γ-chain cytokines IL-2, IL-7, IL-15, and IL-21 play a vital role in peripheral T cell growth and survival. However, the role of common γ-chain cytokines in pulmonary TB (PTB) is poorly understood.

Aim and methods

To examine the association of circulating common γ-chain cytokines with TB disease or infection, we examined the systemic levels of IL-2, IL-7, IL-15, and IL-21 in individuals with PTB, latent TB (LTB) or no TB infection (NTB). We also examined the levels of these cytokines in PTB individuals before and after anti-tuberculosis treatment.

Results

Circulating levels of IL-2, IL-7 and IL-21 were significantly diminished in PTB compared to LTB or NTB individuals. Moreover, TB antigen stimulated whole blood also exhibited diminished levels of common γ-chain cytokines in PTB compared to LTB or NTB individuals. The plasma levels of common γ-chain cytokines exhibited no significant association with the severity or extent of TB disease or with bacterial burdens. However, upon standard anti-TB treatment, both the systemic as well as the TB antigen stimulated levels of IL-2, IL-7 and IL-21 were significantly increased in PTB individuals.

Conclusion

Therefore our data demonstrate that diminished levels of common γ-chain cytokines are a common characteristic of PTB and potentially highlight the importance of boosting these responses to improve treatment outcomes.

IL21R expressing CD14+CD16+ monocytes expand in multiple myeloma patients leading to increased osteoclasts

Bone marrow monocytes are primarily committed to osteoclast formation. It is, however, unknown whether potential primary alterations are specifically present in bone marrow monocytes from patients with multiple myeloma, smoldering myeloma or monoclonal gammopathy of undetermined significance. We analyzed the immunophenotypic and transcriptional profiles of bone marrow CD14⁺ monocytes in a cohort of patients with different types of monoclonal gammopathies to identify alterations involved in myeloma-enhanced osteoclastogenesis. The number of bone marrow CD14⁺CD16⁺ cells was higher in patients with active myeloma than in those with smoldering myeloma or monoclonal gammopathy of undetermined significance. Interestingly, sorted bone marrow CD14⁺CD16⁺ cells from myeloma patients were more pro-osteoclastogenic than CD14⁺CD16-cells in cultures ex vivo. Moreover, transcriptional analysis demonstrated that bone marrow CD14⁺ cells from patients with multiple myeloma (but neither monoclonal gammopathy of undetermined significance nor smoldering myeloma) significantly upregulated genes involved in osteoclast formation, including IL21R. IL21R mRNA over-expression by bone marrow CD14⁺ cells was independent of the presence of interleukin-21. Consistently, interleukin-21 production by T cells as well as levels of interleukin-21 in the bone marrow were not significantly different among monoclonal gammopathies. Thereafter, we showed that IL21R over-expression in CD14⁺ cells increased osteoclast formation. Consistently, interleukin-21 receptor signaling inhibition by Janex 1 suppressed osteoclast differentiation from bone marrow CD14⁺ cells of myeloma patients. Our results indicate that bone marrow monocytes from multiple myeloma patients show distinct features compared to those from patients with indolent monoclonal gammopathies, supporting the role of IL21R over-expression by bone marrow CD14⁺ cells in enhanced osteoclast formation.

IL-21 inhibits IL-17A-producing γδ T-cell response after infection with Bacillus Calmette-Guérin via induction of apoptosis

Innate γδ T cells expressing Vγ6 produce IL-17A at an early stage following infection with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). In this study, we used IL-21 receptor knockout (IL-21R KO) mice and IL-21-producing recombinant BCG mice (rBCG-Ag85B-IL-21) to examine the role of IL-21 in the regulation of IL-17A-producing innate γδ T-cell response following BCG infection. IL-17A-producing Vγ6⁺ γδ T cells increased in the peritoneal cavity of IL-21R KO mice more than in wild type mice after BCG infection. In contrast, the number of IL-17A-producing Vγ6⁺ γδ T cells was significantly lower after inoculation with rBCG-Ag85B-IL-21 compared with control rBCG-Ag85B. Notably, exogenous IL-21 selectively induced apoptosis of IL-17A-producing Vγ6⁺ γδ T cells via Bim. Thus, these results suggest that IL-21 acts as a potent inhibitor of a IL-17A-producing γδ T-cell subset during BCG infection.

The Biological Effects of IL-21 Signaling on B-Cell-Mediated Responses in Organ Transplantation

Antibody-mediated rejection has emerged as one of the major issues limiting the success of organ transplantation. It exerts a highly negative impact on graft function and outcome, and effective treatment is lacking. The triggers for antibody development, and the mechanisms leading to graft dysfunction and failure, are incompletely understood. The production of antibodies is dependent on instructions from various immunocytes including CD4 T-helper cells that secrete interleukin (IL)-21 and interact with antigen-specific B-cells via costimulatory molecules. In this article, we discuss the role of IL-21 in the activation and differentiation of B-cells and consider the mechanisms of IL-21 and B-cell interaction. An improved understanding of the biological mechanisms involved in antibody-mediated complications after organ transplantation could lead to the development of novel therapeutic strategies, which control humoral alloreactivity, potentially preventing and treating graft-threatening antibody-mediated rejection.

Differential Frequency of CD8+ T Cell Subsets in Multiple Sclerosis Patients with Various Clinical Patterns

Recent evidence points to a pathogenic role for CD8⁺ cytotoxic T (Tc) cells in Multiple sclerosis (MS). Based on cytokine profile, Tc cells can be divided into different subsets: IFN-γ (Tc1), IL-4 (Tc2), IL-10 (Tc10), IL-17 (Tc17), IL-21 (Tc21), IL-22 (Tc22) and TNF-α producing cells. In this study we evaluated the frequency of Tc cell subsets and the serum level of Tc17 differentiation cytokines in MS patients with different clinical patterns. We analyzed Tc cell subsets percentage in peripheral blood of relapsing-remitting (RRMS) (n = 28), secondary-progressive (SPMS) (n = 10) and primary-progressive (PPMS) (n = 4) MS patients in comparison to healthy controls (n = 15) using flow cytometry. Serum level of TGF-β, IL-6 and IL-23 were measured by ELISA. We showed elevated levels of Tc1 and Tc17 cells in SPMS and RRMS patients in relapse phase, respectively (P = 0.04). Interestingly, the percentage of TNF-α producing CD8⁺ T cells in relapse and remission phase of RRMS and SPMS patients were higher than controls (P = 0.01, P = 0.004, P = 0.01, respectively) and Tc21 increased in remission phase of RRMS compared to SPMS (P = 0.03). We also found higher frequency of CD8⁺ IFN-γ⁺ TNF-α⁺ IL-17⁺ T cells in relapse phase of RRMS compared to remission phase, SPMS patients and controls (P = 0.01, P = 0.004 and P = 0.02, respectively). TGF- β increased in sera of RRMS patients in remission phase (P = 0.03) and SPMS (P = 0.05) compared to healthy subjects. Increased level of Tc17 and CD8⁺ IFN-γ⁺ TNF-α⁺ IL-17⁺ T cells in relapse phase highlights the critical role of IL-17 in RRMS pathogenesis.

A short CD3/CD28 costimulation combined with IL-21 enhance the generation of human memory stem T cells for adoptive immunotherapy

BACKGROUND

Immunotherapy based on the adoptive transfer of gene modified T cells is an emerging approach for the induction of tumor-specific immune responses. Memory stem T cells, due to their enhanced antitumor and self-renewal capacity, have become potential candidate for adoptive T cell therapy of cancer. Methods to generate memory stem T cells ex vivo rely on CD3/CD28 costimulation and the use of cytokines such as IL-7 and IL-15 during the entire culture period. However, a strong costimulation may induce differentiation of memory stem T cells to effector memory T cells. Here we show that manipulation of the length of the costimulation and addition of IL-21 enhance the ex vivo expansion of memory stem T cells.

METHODS

Purified naïve T cells from healthy donors were cultured in the presence of anti-CD3/CD28 coated beads, IL-7, IL-15 and/or IL-21 (25 ng/ml). T cells phenotype from the different memory and effector subpopulations were analyzed by multiparametric flow cytometry.

RESULTS

A short anti-CD3/CD28 costimulation of naïve T cells, combined with IL-7 and IL-15 significantly increased the frequencies of CD4(+) and CD8(+) memory stem T cells ex vivo, compared to a prolonged costimulation (34.6 ± 4.4 % vs 15.6 ± 4.24 % in CD4(+); p = 0.008, and 20.5 ± 4.00 % vs 7.7 ± 2.53 % in CD8(+); p = 0.02). Moreover, the addition of IL-21 to this condition further enhanced the enrichment and expansion of CD4(+) and CD8(+) memory stem T cells with an increase in the absolute numbers (0.7 × 10(6) ± 0.1 vs 0.26 × 10(6) ± 0.1 cells for CD4(+); p = 0.002 and 1.1 × 10(6) ± 0.1 vs 0.27 × 10(6) ± 0.1 cells for CD8(+); p = 0.0002; short + IL-21 vs long).

CONCLUSIONS

These new in vitro conditions increase the frequencies and expansion of memory stem T cells and may have relevant clinical implications for the generation of this memory T cell subset for adoptive cell therapy of patients with cancer.

Interleukin 21 - its potential role in the therapy of B-cell lymphomas

Interleukin-21 (IL-21), a member of IL-2 cytokine family, has pleotropic biological effects on lymphoid and myeloid cells. During the past 15 years, since the discovery of IL-21, great advances have been made regarding its biological activity and the mechanisms controlling IL-21-mediated cellular responses, especially in hematological malignancies. Preclinical studies have shown that IL-21R is expressed on healthy and neoplastic B-cells and exogenous IL-21 can induce direct apoptosis of IL-21R expressing B-cell non-Hodgkin lymphomas (NHL), making it a potentially attractive anti-lymphoma therapy. However, in some hematological malignancies such as multiple myeloma, Hodgkin lymphoma and Burkitt lymphoma, IL-21 can induce proliferation of neoplastic B-cells. In NHL, the underlying mechanism of cell death was found to be different between the various subtypes, including activation of different JAK/STAT signal transduction pathways or other factors. Immunomodulatory effects of IL-21 have also been reported to contribute to its anti-tumor effects as described by earlier studies in solid tumors and B-cell associated malignancies. These effects are predominantly mediated by IL-21's ability to activate cytolytic activities by NK-cells and CD4⁺/CD8⁺ T-cells. In this review, we provide an overview of IL-21's effects in NHL, results from clinical trials utilizing IL-21, and propose how IL-21 can be therapeutically exploited for treating these lymphomas.

Advances of the interleukin-21 signaling pathway in immunity and angiogenesis

Interleukin-21 (IL-21) and its receptor (IL-21R) are broadly expressed on human B cells, activated T cells and other myeloid cells. IL-21 cooperates with IL-6 and transforming growth factor-β to regulate T-cell differentiation. IL-21-mediated human B cell and dendritic cells differentiation requires signal transducer and activator of transcription 3 (STAT3), and also induces B-cell apoptosis dependents on the Toll-like receptor signal. Recently, in vitro and in vivo experiments showed that IL-21/IL-21R regulate angiogenesis through STAT3. IL-21 signaling pathways are complex due to its cooperation with other transcriptional factors, such as interferon regulatory factor 4 and granulocyte-macrophage colony-stimulating factor. The Janus kinase-STAT pathway has been the most extensively studied. With the increase in the understanding of IL-21 biology in the context of each specific disease or pathological condition, IL-21 could be a new therapeutic target for immune-related disease.

Underground Adaptation to a Hostile Environment: Acute Myeloid Leukemia vs. Natural Killer Cells

Acute myeloid leukemia (AML) is a heterogeneous group of malignancies which incidence increases with age. The disease affects the differentiation of hematopoietic stem or precursor cells in the bone marrow and can be related to abnormal cytogenetic and/or specific mutational patterns. AML blasts can be sensitive to natural killer (NK) cell antitumor response. However, NK cells are frequently defective in AML patients leading to tumor escape. NK cell defects affect not only the expression of the activating NK receptors, including the natural cytotoxicity receptors, the NK group 2, member D, and the DNAX accessory molecule-1, but also cytotoxicity and IFN-γ release. Such perturbations in NK cell physiology could be related to the adaptation of the AML to the immune pressure and more generally to patient’s clinical features. Various mechanisms are potentially involved in the inhibition of NK-cell functions in AML, including defects in the normal lymphopoiesis, reduced expression of activating receptors through cell-to-cell contacts, and production of immunosuppressive soluble agents by leukemic blasts. Therefore, the continuous cross-talk between AML and NK cells participates to the leukemia immune escape and eventually to patient’s relapse. Methods to restore or stimulate NK cells seem to be attractive strategies to treat patients once the complete remission is achieved. Moreover, our capacity in stimulating the NK cell functions could lead to the development of preemptive strategies to eliminate leukemia-initiating cells before the emergence of the disease in elderly individuals presenting preleukemic mutations in hematopoietic stem cells.

Mycobacterium tuberculosis-Specific IL-21+IFN-γ+CD4+ T Cells Are Regulated by IL-12

In the current study of Mycobacterium tuberculosis (MTB)-specific T and B cells, we found that MTB-specific peptides from early secreted antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) induced the expression of IL-21 predominantly in CD4⁺ T cells. A fraction of IL-21-expressing CD4⁺ T cells simultaneously expressed Th1 cytokines but did not secrete Th2 or Th17 cytokines, suggesting that MTB-specific IL-21-expressing CD4⁺ T cells were different from Th1, Th2 and Th17 subpopulations. The majority of MTB-specific IL-21-expressing CD4⁺ T cells co-expressed IFN-γ and IL-21⁺IFN-γ⁺CD4⁺ T cells exhibited obviously polyfunctionality. In addition, MTB-specific IL-21-expressing CD4⁺ T cells displayed a CD45RO⁺CD62L^lowCCR7^lowCD40L^highICOS^high phenotype. Bcl-6-expression was significantly higher in IL-21-expressing CD4⁺ T cells than IL-21^-CD4⁺ T cells. Moreover, IL-12 could up-regulate MTB-specific IL-21 expression, especially the frequency of IL-21⁺IFN-γ⁺CD4⁺ T cells. Taken together, our results demonstrated that MTB-specific IL-21⁺IFN-γ⁺CD4⁺ T cells from local sites of tuberculosis (TB) infection could be enhanced by IL-12, which have the features of both Tfh and Th1 cells and may have an important role in local immune responses against TB infection.