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Background: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and diverse tissue and organ inflammatory affections. Interleukin 21 (IL-21) is implicated in B cell survival, proliferation, differentiation, class switching, and immunoglobulin production; therefore, it is considered a key cytokine in the pathogenesis of SLE. However, its association with disease activity and clinical phenotypes remains unclear. We aimed to evaluate the association of IL-21 levels with the disease activity and clinical phenotypes in patients with SLE. Also, we analyzed the IL21 polymorphisms associated with increased IL-21 levels. Methods: The IL-21 serum levels were determined using the enzyme-linked immunosorbent assay (ELISA) method. The rs2221903 and rs2055979 polymorphisms were assessed in 300 healthy controls (HCs) and 300 patients with SLE by the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique. The levels of IL-21 were monitored during follow-up visits in 59 patients with SLE. Results: The patients with SLE showed higher IL-21 levels compared to the HCs. The IL-21 levels did not correlate with Mex-SLEDAI and were not different in patients with inactive, mild–moderate, and severe disease. The IL-21 levels were increased in patients with hematological affection. The ROC curve analysis revealed that the IL-21 levels had good predictive power in discriminating among patients with SLE and HCs. In a follow-up analysis, the levels of IL-21 remained higher in the patients with SLE even when the patients were in remission. Also, the rs2221903 polymorphism was associated with increased IL-21 levels. Conclusions: This study highlights the importance of IL-21 as a key cytokine in SLE. IL-21 levels are higher in patients with SLE and remain increased regardless of disease activity. According to the ROC analysis, IL-21 is a potential biomarker of SLE. Further longitudinal studies are needed to explore the relationship between IL-21 and the clinical phenotypes of SLE. [ABSTRACT FROM AUTHOR]

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disorder and its characteristics include the immune system's invasion of the healthy lining of the joints and the articular structures degeneration. The IL‐21 pro‐inflammatory cytokine, and the reactive oxygen species (ROS) might have a role in the RA etiopathogenesis. The present study assessed the correlation of IL‐21 with vitamin 25(OH)D and the ROS. Methods: The study included 120 RA patients and 60 healthy group. The RA patients were categorized based on rheumatoid factor (RF) seropositivity or seronegativity and the RA severity. Chemiluminescent immunoassay and 10% hematocrit were used to check levels of vitamin 25(OH)D and ROS, respectively. ELISA was used for the detection of IL‐21 in the plasma. Results: The RA patients had a significantly reduced vitamin 25(OH)D level compared to the healthy controls. The IL‐21 and ROS were however significantly increased in the RA patients compared to the controls. Further, the seropositive RF and the high RA severity patients had significant IL‐21 and ROS increase in comparison with the seronegative RF and the low severity RA patients. Finally, IL‐21 negatively correlated with vitamin 25(OH)D, but positively correlated with the ROS. Conclusion: This is the first investigation to confirm the relationship between IL‐21 with vitamin 25(OH)D and the ROS among the RA patients. The findings indicate that vitamin 25(OH)D is reduced in the RA patients' serum. ROS and IL‐21 are also associated with increased RA severity. [ABSTRACT FROM AUTHOR]

Abstract Background Rheumatoid arthritis (RA) is a chronic autoimmune disorder and its characteristics include the immune system's invasion of the healthy lining of the joints and the articular structures degeneration. The IL‐21 pro‐inflammatory cytokine, and the reactive oxygen species (ROS) might have a role in the RA etiopathogenesis. The present study assessed the correlation of IL‐21 with vitamin 25(OH)D and the ROS. Methods The study included 120 RA patients and 60 healthy group. The RA patients were categorized based on rheumatoid factor (RF) seropositivity or seronegativity and the RA severity. Chemiluminescent immunoassay and 10% hematocrit were used to check levels of vitamin 25(OH)D and ROS, respectively. ELISA was used for the detection of IL‐21 in the plasma. Results The RA patients had a significantly reduced vitamin 25(OH)D level compared to the healthy controls. The IL‐21 and ROS were however significantly increased in the RA patients compared to the controls. Further, the seropositive RF and the high RA severity patients had significant IL‐21 and ROS increase in comparison with the seronegative RF and the low severity RA patients. Finally, IL‐21 negatively correlated with vitamin 25(OH)D, but positively correlated with the ROS. Conclusion This is the first investigation to confirm the relationship between IL‐21 with vitamin 25(OH)D and the ROS among the RA patients. The findings indicate that vitamin 25(OH)D is reduced in the RA patients' serum. ROS and IL‐21 are also associated with increased RA severity.

Background: Sinonasal polyps and allergic rhinitis are prevalent disorders that significantly diminish the standard of living for those who suffer from them. Variants in the interleukin 21 (IL-21) gene have been linked to an increased risk of developing several immune-related diseases. Objective: To examine the correlation between IL-21 gene polymorphisms and the likelihood of developing allergic rhinitis and sinonasal polyps. Patients and Methods: Patients with sinonasal polyps and allergic rhinitis, in addition to a control group, participated in this cross-sectional study. Controls (Group A), patients with AR (Group B), and patients with SNP (Group C) comprised the patient population. TaqMan SNP Genotyping assays were utilised to genotype the IL-21 gene SNP (rs6822844). To identify associations, clinical and genetic data were evaluated. Results: A notable disparity in the distribution of genotypes was identified in the case-control comparison (p < 0.006). In particular, individuals diagnosed with AR had 32 %GG genotypes, 56 %GT genotypes, and 12% TT genotypes. In contrast, the control group demonstrated a mere 4% TT genotypes, 12% GG genotypes, and 84% GT genotypes. The genotype distribution of the SNP patients differed significantly (p < 0.002), with 16% carrying the GG genotype, 60% carrying the GT genotype, and 24% carrying the TT genotype. The distribution of genotypes in the control group comprised 4% TT genotypes, 84% GT genotypes, and 12% GG genotypes. Conclusion: It is possible that Egyptians with certain IL-21 gene variants are more likely to suffer from allergic rhinitis and sinonasal polyps. [ABSTRACT FROM AUTHOR]

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and diverse tissue and organ inflammatory affections. Interleukin 21 (IL-21) is implicated in B cell survival, proliferation, differentiation, class switching, and immunoglobulin production; therefore, it is considered a key cytokine in the pathogenesis of SLE. However, its association with disease activity and clinical phenotypes remains unclear. We aimed to evaluate the association of IL-21 levels with the disease activity and clinical phenotypes in patients with SLE. Also, we analyzed the IL21 polymorphisms associated with increased IL-21 levels. Methods: The IL-21 serum levels were determined using the enzyme-linked immunosorbent assay (ELISA) method. The rs2221903 and rs2055979 polymorphisms were assessed in 300 healthy controls (HCs) and 300 patients with SLE by the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique. The levels of IL-21 were monitored during follow-up visits in 59 patients with SLE. Results: The patients with SLE showed higher IL-21 levels compared to the HCs. The IL-21 levels did not correlate with Mex-SLEDAI and were not different in patients with inactive, mild–moderate, and severe disease. The IL-21 levels were increased in patients with hematological affection. The ROC curve analysis revealed that the IL-21 levels had good predictive power in discriminating among patients with SLE and HCs. In a follow-up analysis, the levels of IL-21 remained higher in the patients with SLE even when the patients were in remission. Also, the rs2221903 polymorphism was associated with increased IL-21 levels. Conclusions: This study highlights the importance of IL-21 as a key cytokine in SLE. IL-21 levels are higher in patients with SLE and remain increased regardless of disease activity. According to the ROC analysis, IL-21 is a potential biomarker of SLE. Further longitudinal studies are needed to explore the relationship between IL-21 and the clinical phenotypes of SLE.

Artificial antigen‐presenting cells (aAPCs) offer a cost effective and convenient tool for the expansion of chimeric antigen receptor (CAR)‐bearing T cells and NK cells. aAPCs are particularly useful because of their ability to efficiently expand low‐frequency antigen‐reactive lymphocytes in bulk cultures. Commonly derived from the leukemic cell line K562, these aAPCs lack most major histocompatibility complex expression and are therefore useful for NK cell expansion without triggering allogeneic T‐cell proliferation. To combat difficulties in accessing existing aAPC lines, while circumventing the iterative lentiviral gene transfers with antibody‐mediated sorting required for the isolation of stable aAPC clones, we developed a single‐step technique using Sleeping Beauty (SB)–based vectors with antibiotic selection options. Our SB vectors contain options of two to three genes encoding costimulatory molecules, membrane‐bound cytokines as well as the presence of antibiotic‐resistance genes that allow for stable transposition‐based transfection of feeder cells. Transfection of K562 with SB vectors described in this study allows for the surface expression of CD86, 4‐1BBL, membrane‐bound (mb) interleukin (IL)‐15 and mbIL‐21 after simultaneous transposition and antibiotic selection using only two antibiotics. aAPCs successfully expanded NK cells to high purity (80–95%). Expanded NK cells could be further engineered by lentiviral CAR transduction. The multivector kit set is publicly available and will allow convenient and reproducible in‐house production of effective aAPCs for the in vitro expansion of primary cells. [ABSTRACT FROM AUTHOR]

Interleukin 21 (IL-21) is a receptor participating in innate immunity and correlates with the activation of innate immune cells. We sought to investigate the role of plasma IL-21 in patients with idiopathic membranous nephropathy (IMN).

Interleukin (IL) 21 is a pleiotropic cytokine that plays an important role in regulating innate and adaptive immune responses. In fish, the biological functions and cell source of IL-21 remain largely unknown. In this study, we performed qRT-PCR, Western blotting and immunofluorescent microscopy to examine the expression of IL-21 at the mRNA and protein levels. We found that il21 expression was induced in the primary head kidney leukocytes of grass carp (Ctenopharyngodon idella) by heat-inactivated Aeromonas hydrophila (A. hydrophila) and LPS and in tissues after infection with A. hydrophila. Recombinant IL-21 protein produced in the CHO-S cells was effective in elevating the expression of antibacterial genes, including β-defensin and lysozyme, and, interestingly, inhibited the NF-κB signaling pathway. Furthermore, we investigated the response of the IL-21 expressing cells to A. hydrophila infection. Immunofluorescent assay showed that IL-21 protein was detected in the CD3γ/δ T cells and was markedly accumulated in the anterior, middle and posterior intestine. Collectively, the results indicate that IL-21 plays an important role in regulating the intestinal inflammation induced by bacterial infection in grass carp. [ABSTRACT FROM AUTHOR]

Interleukin (IL) 21 is a pleiotropic cytokine that plays an important role in regulating innate and adaptive immune responses. In fish, the biological functions and cell source of IL-21 remain largely unknown. In this study, we performed qRT-PCR, Western blotting and immunofluorescent microscopy to examine the expression of IL-21 at the mRNA and protein levels. We found that il21 expression was induced in the primary head kidney leukocytes of grass carp (Ctenopharyngodon idella) by heat-inactivated Aeromonas hydrophila (A. hydrophila) and LPS and in tissues after infection with A. hydrophila. Recombinant IL-21 protein produced in the CHO-S cells was effective in elevating the expression of antibacterial genes, including β-defensin and lysozyme, and, interestingly, inhibited the NF-κB signaling pathway. Furthermore, we investigated the response of the IL-21 expressing cells to A. hydrophila infection. Immunofluorescent assay showed that IL-21 protein was detected in the CD3γ/δ T cells and was markedly accumulated in the anterior, middle and posterior intestine. Collectively, the results indicate that IL-21 plays an important role in regulating the intestinal inflammation induced by bacterial infection in grass carp.

Background/aim: COVID-19 patients have a wide spectrum of disease severity. Several biomarkers were evaluated as predictors for progression towards severe disease. IL-21 is a member of common γ-chain cytokine family and creates some specific effects during programming and maintenance of antiviral immunity. We aimed to assess IL-21 as a biomarker for diagnosis and outcome prediction in patients hospitalized with COVID-19. Materials and methods: Patients with a preliminary diagnosis of COVID-19 and pneumonia other than COVID-19 admitted to a tertiary care hospital were included consecutively in this comparative study. Results: The study population consisted of 51 patients with COVID-19 and 11 patients with non-COVID-19 pneumonia. Serum IL-21 concentration was markedly higher, and serum CRP concentration was significantly lower in COVID-19 patients compared to nonCOVID-19 pneumonia patients. Within COVID-19 patients, 10 patients showed radiological and clinical progression. Patients with clinical worsening had lower lymphocyte count and haemoglobin. In addition to that, deteriorating patients had higher urea, LDH levels, and elevated concentration of both IL-6 and IL-21. The cut-off value of 106 ng/L for IL-21 has 80.0% sensitivity, %60.9 specificity for discriminating patients with clinical worsening. Multivariable analysis performed to define risk factors for disease progression identified IL-6 and IL-21 as independent predictors. Odds ratio for serum IL-6 concentrations ≥ 3.2 pg/mL was 8.07 (95% CI: 1.37- 47.50, p = 0.04) and odds ratio for serum IL-21 concentrations ≥ 106 ng/L was 6.24 (95% CI: 1.04 – 37.3, p = 0.02). Conclusion: We identified specific differences in serum IL-21 between COVID-19 and non-COVID-19 pneumonia patients. Serum IL-21 measurement has promising predictive value for disease progression in COVID-19 patients. High serum IL-6 and IL-21 levels obtained upon admission are independent risk factors for clinical worsening. [ABSTRACT FROM AUTHOR]

In the era of immune checkpoint blockade cancer therapy, cytokines have become an attractive immune therapeutics to increase response rates. Interleukin 21 (IL21) as a single agent has been evaluated for cancer treatment with good clinical efficacy. However, the clinical application of IL21 is limited by a short half-life and concern about potential immune suppressive effect on dendritic cells. Here, we examined the antitumor function of a half-life extended IL21 alone and in combination with PD-1 blockade using preclinical mouse tumor models. We also determined the immune mechanisms of combination therapy. We found that combination therapy additively inhibited the growth of mouse tumors by increasing the effector function of type 1 lymphocytes. Combination therapy also increased the fraction of type 1 dendritic cells (DC1s) and M1 macrophages in the tumor microenvironment (TME). However, combination therapy also induced immune regulatory mechanisms, including the checkpoint molecules Tim-3, Lag-3, and CD39, as well as myeloid derived suppressor cells (MDSC). This study reveals the mechanisms of IL21/PD-1 cooperation and shed light on rational design of novel combination cancer immunotherapy.

Breakthrough infections of hepatitis B virus (HBV) after neonatal vaccination occurred in some adolescents and young adults who were born to mothers with hepatitis B surface antigen (HBsAg). We aimed to determine the impacts of prenatal HBsAg exposure on the generation of T follicular helper (Tfh) cells and antibodies (anti-HBs) specific to HBsAg. To mimic human prenatal HBsAg exposure, we mated female Alb1-HBV (HBV-M) mice with male C57BL/6J mice. Of their first filial generation (F1), HBV-M/F1+ expressed HBsAg in liver tissues and blood, and HBV-M/F1− mice exposed HBsAg in amniotic fluid. At their four weeks old, each HBV-M/F1 mouse was immunized with hepatitis B vaccine containing 5 μg HBsAg subcutaneously. Both HBV-M/F1− and HBV-M/F1+ mice had reduced generation of HBsAg-specific CD4+CXCR5+PD1+ Tfh cells and CD138+IgD− plasma cells in comparison with C57BL/6J mice. Results of coculturing the Tfh cells with B cells that were isolated from different strains of mice indicated that CD4+ T cell activation in response to HBsAg was critical for anti-HBs generation after prenatal HBsAg exposure. When interleukin (IL) 21 was supplemented, the generation of HBsAg-specific Tfh and plasma cells in HBV-M/F1− mice was improved, while supplementation showed little effect in HBV-M/F1+ mice. In HBV-M/F1− mice, HBV vaccine booster improved the generation of Tfh cells and plasma cells, and enhanced anti-HBs production. Impaired generation of HBsAg-specific Tfh cells and plasma cells after prenatal HBsAg exposure can be improved by HBV vaccine booster, most likely increasing IL-21 production. [ABSTRACT FROM AUTHOR]

• IL-21 promotes expansion of CAR 19 T cells after antigenic restimulation by maintanence of early memory phenotype and by reduction of apoptosis. • Inducibly secreted IL-21 stimulates the proliferation of CAR T cells after a co-culture with tumor cells and enhances their anti-tumor efficacy in NSG mice. • CAR 19 T cells armed with IL-21 are resistant to immunosupression induced by chronic lymphocytic leukemia cells and display enhanced proliferation and effector functions The efficiency of chimeric antigen receptor (CAR) T-cell-based therapies depends on a sufficient expansion of CAR T cells in vivo and can be weakened by intra-tumoral suppression of CAR T cell functions, leading to a failure of therapy. For example, certain B-cell malignancies such as chronic lymphocytic leukemia are weakly sensitive to treatment with CAR T cells. Co-expression of proinflamatory cytokines such as IL-12 and IL-18 by CAR T cells have been shown to enhance their antitumor function. We similarly engineered CAR T cell to co-express IL-21 and studied the effects of IL-21 on CAR T cells specific to CD19 and prostate-specific membrane antigens using an in vitro co-culture model and NSG mice transplanted with B-cell tumors. IL-21 enhanced the expansion of CAR T cells after antigenic stimulation, reduced the level of apoptosis of CAR T cells during co-culture with tumor cells and prevented differentiation of CAR T cells toward late memory phenotypes. In addition, induced secretion of IL-21 by CAR T cells promoted tumor infiltration by CD19-specific CAR (CAR19) T cells in NSG mice, resulting in reduced tumor growth. By co-culturing CAR19 T cells with bone-marrow fragments infiltrated with CLL cells we demonstrate that IL-21 reduces the immunosupressive activity of CLL cells against CAR19 T cells. CAR19 T cells armed with IL-21 exhibited enhanced antitumor functions. IL-21 promoted their proliferation and cytotoxicity against chronic lymphocytic leukemia (CLL). The results suggest that arming CAR T cells with IL-21 could boost the effectiveness of CAR T-mediated therapies. [ABSTRACT FROM AUTHOR]

The aim of the analysis was for the first time to assess the expression of genes encoding IL-21 and IL-22 at the mRNA level in ovarian tumor specimens and the concentration of these parameters in serum and peritoneal fluid in patients with ovarian serous cancer. The levels of IL-21 and IL-22 transcripts were evaluated with the use of the real-time RT-qPCR. Enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of proteins. Quantitative analysis of IL-21 gene mRNA in the tumor tissue showed the highest activity in the G1 degree of histopathological differentiation and was higher in G1 compared to the control group. The concentration of IL-21 and IL-22 in the serum and in the peritoneal fluid of women with ovarian cancer varied depending on the degree of histopathological differentiation of the cancer and showed statistical variability compared to controls. The conducted studies have shown that the local and systemic changes in the immune system involving IL-21 and IL-22 indicate the participation of these parameters in the pathogenesis of ovarian cancer, and modulation in the IL-21/IL-22 system may prove useful in the development of new diagnostic and therapeutic strategies used in patients, which require further research.

Background: Interleukin (IL)-21 is a member of the type I cytokine family and plays a role in the pathogenesis of T helper type 2 allergic diseases. It has been reported that IL-21 expression is upregulated in acute skin lesions in atopic dermatitis (AD) patients; however, little is known about the serum IL-21 levels of AD patients. The aim of this study was to quantify the serum IL-21 levels of AD patients and to evaluate the relationships between the serum IL-21 level and disease severity, laboratory markers, and eruption type in AD patients. Methods: We measured the serum IL-21 levels of adult AD patients and healthy control subjects using an enzyme-linked immunosorbent assay. Results: The adult AD patients exhibited significantly higher serum IL-21 levels than the healthy control subjects. A comparison of the patients' serum IL-21 levels based on the clinical severity of their AD revealed that the patients with severe AD demonstrated significantly higher serum IL-21 levels than those with mild AD and the healthy control subjects. The serum IL-21 levels were significantly correlated with the skin severity score, and especially with the degree of acute lesions such as erythema and edema/papules. The serum IL-21 level was not associated with laboratory markers, such as the serum IgE level, the serum thymus and activation-related chemokine level, blood eosinophilia, and the serum lactate dehydrogenase level. Conclusions: These results suggest that IL-21 might be involved in the pathogenesis of AD, especially the development of acute skin lesions.

Background: The immunopathologic mechanism underlying dermatomyositis (DM) and polymyositis (PM) remains poorly understood. Many cytokines play a pathogenic role in DM and PM. Interleukin 21 (IL-21) has a pleiotropic effect on inflammation regulation. This study aimed to detect the serum IL-21 level and investigate the expression of IL-21 and IL-21 receptor (IL-21R) in muscle tissues of patients with DM and PM. Methods: Biopsied muscle samples were obtained from 11 patients with DM, 12 with PM, and six controls; mRNA levels of IL-21 and IL-21R were analyzed by real-time quantitative reverse transcription-polymerase chain reaction; and immunohistochemical staining was used to evaluate the protein expression of IL-21 and IL-21R. Serum samples were obtained from 36 patients with DM, 19 with PM, and 20 healthy controls. The serum IL-21 level was detected by enzyme-linked immunosorbent assay. Results: The expression of IL-21 was upregulated in patients with DM and PM. The IL-21 mRNA level was significantly increased in muscle tissues of patients with DM and PM (DM vs. control, P= 0.001; PM vs. control, P= 0.001), whereas IL-21R mRNA level in patients with DM/PM was not statistically different from that of healthy controls. Immunohistochemical staining showed both IL-21 and IL-21R were significantly expressed in the inflammatory cells in muscle tissues of patients with DM and PM. The serum IL-21 level was also significantly higher in patients with DM/PM than in controls (DM vs. control, 49.12 [45.28, 60.07] pg/ml vs. 42.54 [38.69, 48.85] pg/ml, P= 0.001; PM vs. control, 50.77 [44.19, 60.62] pg/ml vs. 42.54 [38.69, 48.85] pg/ml, P= 0.005). Conclusions: IL-21 expression is upregulated in patients with DM and PM in both muscle tissue and serum. In addition, IL-21R protein is highly expressed in affected muscle tissues of patients with DM and PM. IL-21 may play a pathogenic role through IL-21R in patients with DM and PM.

Backgroud There is an unmet need for the development of new biomarkers for idiopathic inflammatory myopathy-associated interstitial lung disease (IIM-ILD). Methods Peripheral CD4+CXCR4+ T cells, stromal cell-derived factor-1 and Krebs von den Lungen-6 were measured in patients with IIM-ILD (n = 85) and controls. The relation to pulmonary functions, high-resolution CT scores, specific clinical phenotypes and survival was analysed. Cytokine-expression profiling of these CD4+CXCR4+ T cells and their co-culture with pulmonary fibroblasts were conducted. Results The peripheral percentages of CD4+CXCR4+ T cells were significantly elevated in IIM-ILD patients, and correlated with high-resolution CT score (r = 0.7136, P < 0.0001) and pulmonary function impairments, such as percentage of forced volume vital capacity (r = −0.4734, P = 0.0005). They were associated with anti-melanoma differentiation-associated gene 5 autoantibodies and the amyopathic DM phenotype. In IIM-ILD, peripheral percentages of CD4+CXCR4+ T cells ⩾30% revealed a 6-month mortality as high as 47%. These CD4+CXCR4+ T cells express high levels of IL-21 and IL-6. In vitro blockade of IL-21 signalling by neutralization of IL-21 or Janus kinase inhibitor could abolished the fibroblast proliferation. Conclusion Overall, peripheral CD4+CXCR4+ T cells appear to be a potentially valuable novel biomarker associated with the severity and prognosis of IIM-ILD. They promote pulmonary fibroblast proliferation via IL-21, which may herald future targeted treatments for this severe disease. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Nowadays, bronchial asthma is still a severe disease threatening human health, and it is incumbent upon us to seek effective therapeutic drugs. Mahuang decoction (MHD), a classic famous Chinese prescription, has been used for thousands of years to prevent phlegm from forming, stop coughing and relieve asthma, but the relevant mechanism has not been thoroughly clarified. This study aims to investigate the anti-airway inflammation effect of MHD and the possible molecular mechanism underlying IL21/STAT3 signaling pathway, so as to provide guidance for the treatment of MHD on bronchial asthma. Materials and methods Specific pathogen free SD rats were randomly divided into 6 groups: normal control group, model group, positive group (Compound methoxyphenamine), MHD-treated groups at doses of 10 ml/kg, 5 ml/kg and 2.5 ml/kg, 10 rats in each group. Except for the normal control group, rats in other groups were sensitized with ovalbumin via introperitoneal injection and challenged with ovalbumin inhalation to trigger asthma model. At 24 h after the last excitation, bronchoalveolar lavage fluid (BALF) of every rat was drawn and the number of inflammatory cells was analyzed using cell counting method. ELISA method was performed to determine the concentrations of TXB 2 , 6-keto-PGF 1α , MMP-9, TIMP-1, IL-2, IL-4, IL-5 and TNF-α in rat serum. The protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in murine pulmonary tissues were assessed with western blotting analysis. Results Compared with the control group, the airway wall and airway smooth muscle of murine pulmonary tissues significantly thickened and massive inflammatory cells infiltration occurred around the bronchus in the model group, and the cell counts of WBC and EOS in BALF were also apparently increased, which indicated the rat asthma model was successfully established. MHD or Compound methoxyphenamine not only alleviated the pulmonary inflammatory pathological damages, but also down- regulated the numbers of WBC and EOS in BALF. What's more, the levels of TXB 2 , MMP-9, TIMP-1, ILs-(2, 4, 5) and TNF-α in rat serum were lessened by the treatment of MHD. In western blotting analysis, treatment with 10 ml/kg or 5 ml/kg MHD markedly declined the increased protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in lung tissues of asthmatic rats to normal level. Conclusion MHD intervention demonstrated a strong inhibitory action on the secretion of inflammatory mediators as well as the inflammatory cell infiltration in pulmonary tissues of asthmatic rats, and also depressed the protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in pulmonary tissues. MHD effectively mitigates airway inflammation and regulates the IL-21/STAT3 signaling pathway in rat asthma model. [ABSTRACT FROM AUTHOR]

Background and aims. Autoimmune hepatitis (AIH) is a chronic inflammatory condition of the liver in which the immunological mechanisms involved in tissue destruction and/or repair are still unclear. Different pro-inflammatory cytokines have been shown to play a determinant role in AIH pathogenesis. Here, we aim to compare the circulating levels of pro-and anti-inflammatory cytokines such as IL-6, TNF-α, IL-17A/F, IL-21, IL-22, IL-23, and IL-10 in patients with type 2 AIH compared to patients with type 1 AIH and healthy controls (HC). Fourty-six Mexican patients with AIH were recruited in our study. Patients were classified as type 1 or 2 AIH based on immune serological markers. Fourty-four serum samples from healthy individuals were included as controls. Serum cytokine levels were determined by ELISA technique.Results. Compared to healthy controls, serum levels of IL-17F, IL-21, IL-23, IL-10, IL-6, and TNF-α, but not IL-17A and IL-22, were significantly increased in AIH patients. When patients were grouped by aminotransferase activity, a biomarker of active disease, a positive correlation between serum IL-17F and alanine transaminase (rs: 0.4739; P = 0.0009) and aspartate transaminase (rs: 0.4984; P = 0.0004) levels was found. A cytokine signature profile associated with type 2 AIH was characterized by high serum IL-21 (type 1 AIH: 0.66 pg/mL; type 2 AIH: 331.1 pg/mL; P = 0.0042) and IL-22 (type 1 AIH: 0.1 pg/mL; type 2 AIH: 55.26 pg/mL; P = 0.0028) levels.Conclusions. We show for the first time, differential regulation of certain pro-inflammatory cytokines associated with disease progression and AIH type in Mexican patients.

Recent advances in cancer treatment with checkpoint blockade of receptors such as CTLA-4 and PD-1 have demonstrated that combinations of agents with complementary immunomodulatory effects have the potential to enhance antitumor activity as compared to single agents. We investigated the efficacy of immune-modulatory interleukin-21 (IL-21) combined with checkpoint blockade in several syngeneic mouse tumor models. After tumor establishment, mice were administered recombinant mouse IL-21 (mIL-21) alone or in combination with blocking monoclonal antibodies against mouse PD-1 or CTLA-4. In contrast to monotherapy, IL-21 enhanced antitumor activity of mCTLA-4 mAb in four models and anti-PD-1 mAb in two models, with evidence of synergy for one or both of the combination treatments in the EMT-6 and MC38 models. The enhanced efficacy was associated with increased intratumoral CD8+ T cell infiltrates, CD8+ T cell proliferation, and increased effector memory T cells, along with decreased frequency of central memory CD8+ T cells. In vivo depletion of CD8+ T cells abolished the antitumor activities observed for both combination and monotherapy treatments, further supporting a beneficial role for CD8+ T cells. In all studies, the combination therapies were well tolerated. These results support the hypothesis that the combination of recombinant human IL-21 with CTLA-4 or PD-1 monoclonal antibodies could lead to improved outcomes in cancer patients.

Background/aim: Recently, novel studies on the pivotal role of B cells in the tumor-microenvironment and anti-tumor immunity have been conducted. Additionally, Interleukin-21 (IL-21) and anti-B cell receptor (BCR) have been reported to stimulate B cells to secrete granzyme B, which exhibits cytotoxic effects on tumor cells. However, the direct anti-tumor effect of B cells is not yet fully understood in the veterinary field. This study is the first attempt in veterinary medicine to identify the immediate effect of B cells on tumor suppression and the underlying mechanisms involved., Materials and Methods: Canine B cells were isolated from peripheral blood and activated with IL-21 and anti-B cell receptor (BCR). The canine leukemia cell line GL-1 was co-cultured with B cells, and the anti-tumor effect was confirmed by assessing the changes in cell viability and apoptotic ratio., Results: When B cells were activated with IL-21 and anti-BCR, the secretion of granzyme B and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) increased. Simultaneously, the viability of GL-1 cells decreased, and the apoptotic ratio increased, particularly when co-cultured with activated B cells., Conclusion: The results demonstrated the direct anti-tumor effect of granzyme B-and TRAIL and its enhanced potential of B cells to inhibit tumor cell growth after activation with IL-21 and anti-BCR. This study is the first study dealing with immunomodulation in the canine tumor micro-environment., (Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background. Interleukin 21 (IL-21), which belongs to the common γ-chain (γc) family, is a novel tumor suppressor that has been shown to affect T-cell proliferation, survival and function. However, the role of IL-21 in colon cancer remains unclear. Objectives. We sought to determine whether IL-21 could inhibit the progression of colon cancer in mice; we also explored the mechanisms underlying the immunological effects of IL-21 in colon cancer. Material and methods. Exogenous IL-21 protein was expressed to treat tumor-bearing mice and the production of cytokine interleukin 4, interferon gamma and lambda from CD4+ T, CD8+ T, and NK cells were measured, along with the survival times of these tumor-bearing mice. Results. Interleukin 21 promoted the secretion of interferon gamma from the CD4+ T, CD8+ T and NK cells and it enhanced the production of interferon lambda by the NK cells. More importantly, IL-21 treatment significantly enhanced antitumor effects in favor of tumor eradication. We also found that CD8+ T and NK cells are necessary for the antitumor immune responses elicited by IL-21. Conclusions. Interleukin 21 is a powerful tool for activating CD8+ T cells and NK cells which exhibit potent cytolytic effector functions and should therefore be exploited for anticancer immunotherapy. Our findings support the development of a novel cytokine immunotherapy against colon cancer. [ABSTRACT FROM AUTHOR]

In vitro fertilization-embryo transfer (IVF-ET) can be used by infertile couples to assist with reproduction; however, failure of the embryo to implant into the endometrial lining results in failure of the IVF treatment. The present study investigated the expression of chemokine receptor 7 (CCR7)(lo) programmed death-1(PD-1)(hi) chemokine receptor type 5 (CXCR5)+ cluster of differentiation 4 (CD4)+ T cells and associated factors in patients with repeated implantation failure (RIF). A total of 30 females with RIF and 30 healthy females were enrolled in the current study. Flow cytometry was used to detect the proportion of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells in the peripheral blood. Cytokine bead arrays were performed to detect the levels of interleukin (IL)-6, -4 and -2 in the serum. ELISAs were used to detect the level of IL-21 in the serum. Quantitative real time polymerase chain reaction analysis and immunohistochemistry were used to investigate the expression of B-cell lymphoma 6 (Bcl-6), chemokine receptor type 5 (CXCR5) and IL-21 in the endometrium. The results revealed that the percentage of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells was increased in the RIF group compared with the control group during the mid luteal phase. The mRNA and protein levels of Bcl-6, IL-21 and CXCR5 in the endometrium and the concentrations of IL-21 and IL-6 in the serum were significantly increased in the RIF group; however, no significant difference was observed between the two groups in regards to the expression of IL-4 and IL-2. Furthermore, a significant positive correlation was identified between the percentage of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells and IL-21 and IL-6 levels. The expression of IL-21 also had a positive correlation with Bcl-6 and CXCR5 expression in the RIF group. These results suggest that increased levels of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells and associated factors contribute to RIF and could therefore be a potential therapeutic target. [ABSTRACT FROM AUTHOR]

Interleukin 21 (IL-21) is crucial for the development of a robust CD8+ T cell response and has been shown to promote antitumor immunity. Despite the fact that osteosarcoma presents significant genetic instability with a high immunogenic potential, the antitumor immune response in osteosarcoma is ineffective. We investigated whether this was due to impaired IL-21 responses. We found that the circulating CD4+ T cells, a major source of IL-21, had reduced capacity to express IL-21 in osteosarcoma patients compared to healthy controls. The IL-21 expression in healthy controls was equally shared between Th17 and follicular helper T (Tfh) cells, while in osteosarcoma patients, the Tfh cells presented a severe reduction in IL-21 secretion capacity as well as in proliferation capacity. To explain this loss of Tfh functionality, we found that Tfh cells expressed the highest level of PD-1 among all CD4+ T cell subsets examined. While PD-1 might be crucial for normal Tfh function in healthy individuals, in patients with programmed death ligand 1 (PD-L1)+ tumor, the PD-1/PD-L1 pathway on Tfh cells might be sabotaged to mediate immunosuppression. Indeed, the IL-21 production by Tfh cells was significantly reduced in the presence of PD-L1+ tumor cells and was rescued by the anti-PD-L1 antibody. In healthy individuals, CXCR5+ Tfh cells could enhance the interferon (IFN)-g secretion, degranulation, and cytotoxicity of CD8+ T cells, but this function of Tfh cells was lost in osteosarcoma patients. Together, this study demonstrated a dysregulated pathway that should be targeted for future immunotherapies in osteosarcoma. [ABSTRACT FROM AUTHOR]

Background Interleukin (IL)-21 is a member of the type I cytokine family and plays a role in the pathogenesis of T helper type 2 allergic diseases. It has been reported that IL-21 expression is upregulated in acute skin lesions in atopic dermatitis (AD) patients; however, little is known about the serum IL-21 levels of AD patients. The aim of this study was to quantify the serum IL-21 levels of AD patients and to evaluate the relationships between the serum IL-21 level and disease severity, laboratory markers, and eruption type in AD patients. Methods We measured the serum IL-21 levels of adult AD patients and healthy control subjects using an enzyme-linked immunosorbent assay. Results The adult AD patients exhibited significantly higher serum IL-21 levels than the healthy control subjects. A comparison of the patients' serum IL-21 levels based on the clinical severity of their AD revealed that the patients with severe AD demonstrated significantly higher serum IL-21 levels than those with mild AD and the healthy control subjects. The serum IL-21 levels were significantly correlated with the skin severity score, and especially with the degree of acute lesions such as erythema and edema/papules. The serum IL-21 level was not associated with laboratory markers, such as the serum IgE level, the serum thymus and activation-related chemokine level, blood eosinophilia, and the serum lactate dehydrogenase level. Conclusions These results suggest that IL-21 might be involved in the pathogenesis of AD, especially the development of acute skin lesions. [ABSTRACT FROM AUTHOR]

In the present study, adenovirus-mediated interleukin 21 (Ad5-IL-21-EGFP) gene expression was induced in Hepa1-6 cells to investigate whether IL-21 was capable of enhancing antitumor immunity and reducing tumorigenicity of Hepa1-6 in a mouse model. Mice were inoculated intradermally into the right flank with Hepa1-6 cells or Hepa1-6 cells infected with Ad5 or Ad5-IL-21. Four weeks later, the mice were sacrificed humanely, and the tumor volume, tumor weight and mouse spleen index were measured. The levels of IL-21, IL-4 and interferon (IFN)-γ levels in mouse serum and tumor tissues were detected by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. Cell counting kit-8 (CCK-8) assay was used to detect the killing ability of spleen T cells and natural killer (NK) cells, and the proliferation ability of T cells. The expression of IL-21 was confirmed by reverse transcription-polymerase chain reaction, western blot analysis and ELISA assay in Ad5-IL-21-EGFP-infected Hepa1-6 cells. The overexpression of IL-21 significantly reduced the tumorigenicity of Hepa1-6 cells. The tumor volumes and tumor weights in Ad5-IL-21-Hepa1-6 mice were much smaller than those in the Ad5-Hepa1-6 group and Hepa1-6 wild-type group. The immunohistochemistry and ELISA assay demonstrated that IL-21 and IFN-γ levels were much higher while the IL-4 level was much lower in the Ad5-IL-21-Hepa1-6 group than in the other two groups. CCK-8 assay revealed that the killing ability of NK cells and T cells, and the proliferation ability of T cells in Ad5-IL-21-Hepa1-6 mice were higher than in the other two groups; the spleen index of Ad5-IL-21-Hepa1-6 mice was also higher than in the other groups. The data had a significant difference (P<0.01). In conclusion, IL-21 reduces tumorigenicity of Hepa1-6 by a mechanism involving enhanced activation of cell-mediated immunity in tumor-bearing mice. [ABSTRACT FROM AUTHOR]

Background: Circulating follicular helper T (Tfh) cells are a heterogeneous population of CD4+ helper T cells that promotes pathogenic immune responses in autoimmune diseases. In this study, we examined the status of different subpopulations of Tfh cells in peripheral circulation and their associations with various clinical characteristics of IgA vasculitis (IgAV). Methods: According to the phenotypic expressions of different molecules, focus was given on six subpopulations of Tfh cells: CD4+CXCR5+, CD4+CXCR5+ICOS+, CD4+CXCR5+ICOS+PD-1+, CD4+CXCR5+ICOShighPD-1high, CD4+CXCR5+ ICOS-PD-1+, and CXCR5+CD45RA-IL-21+. The frequencies of these six subpopulations and the circulating level of Tfh-related cytokine interleukin 21 (IL-21) were measured from 27 patients with IgAV and 15 healthy controls (HC) by flow cytometry and flow cytometric bead array, respectively. Results: Significantly higher frequencies of CD4+CXCR5+, CD4+CXCR5+ICOS+, CD4+CXCR5+ICOS+PD-1+, CD4+CXCR5+ ICOShighPD-1high and CXCR5+CD45RA-IL-21+ Tfh cells, as well as higher levels of plasma IL-21, were detected in IgAV patients compared to HC. The level of each Tfh subpopulation varied by the presenting symptoms of IgAV, but did not differ between patients treated or not treated with glucocorticoids. When the disease entered the remission stage following treatment, circulating levels of CD4+CXCR5+, CD4+CXCR5+ICOS+, CD4+CXCR5+ICOS+PD-1+, CD4+CXCR5+ ICOShighPD-1high and CXCR5+CD45RA-IL-21+ Tfh cells, as well as plasma IL-21 levels were reduced. Among the six subpopulations of Tfh cells, both CD4+CXCR5+ICOS+ and CXCR5+CD45RA-IL-21+ significantly and positively correlated with serum IgA and plasma IL-21 levels, but only CXCR5+CD45RA-IL-21+ significantly and negatively correlated with the serum C4 level. Conclusions: Tfh cells may differentially contribute to the development of IgAV or predict disease progression. These findings provide novel insights in the pathogenesis of IgAV and may benefit treatment development targeting organspecific presenting symptoms of IgAV. [ABSTRACT FROM AUTHOR]