IL-17 Expression In CD4 Research Articles

Identification of a transcription factor network regulating anti-TNF mediated IL10 expression in human CD4+ T cells.

CD4+ T cells are key players in immune-mediated inflammatory diseases (IMIDs) through the production of inflammatory mediators including tumour necrosis factor (TNF). Anti-TNF therapy has revolutionized the treatment of several IMIDs and we previously demonstrated that in vitro treatment of human CD4+ T cells with anti-TNF promotes anti-inflammatory IL-10 expression in multiple subpopulations of CD4+ T cells. Here we investigated the transcriptional mechanisms underlying the IL-10 induction by TNF-blockade in CD4+ T cells, isolated from PBMCs of healthy volunteers, stimulated in vitro for 3 days with anti-CD3/CD28 mAb in the absence or presence of anti-TNF. After culture, CD45RA+ cells were depleted before performing gene expression profiling and chromatin accessibility analysis. Gene expression analysis of CD45RA-CD4+ T cells showed a distinct anti-TNF specific gene signature of 183 genes (q-value < 0.05). Pathway enrichment analysis of differentially expressed genes revealed multiple pathways related to cytokine signalling and regulation of cytokine production; in particular, IL10 was the most upregulated gene by anti-TNF, while the proinflammatory cytokines and chemokines IFNG, IL9, IL22, and CXCL10 were significantly downregulated (q-value < 0.05). Transcription factor motif analysis at the differentially open chromatin regions, after anti-TNF treatment, revealed 58 transcription factor motifs enriched at the IL10 locus. We identified seven transcription factor candidates for the anti-TNF mediated regulation of IL-10, which were either differentially expressed or whose locus was differentially accessible upon anti-TNF treatment. Correlation analysis between the expression of these transcription factors and IL10 suggests a role for MAF, PRDM1, and/or EOMES in regulating IL10 expression in CD4+ T cells upon anti-TNF treatment.

Bhlhe40 limits early IL-10 production from CD4+ T cells during Plasmodium yoelii 17X infection.

The cytokine IL-10 suppresses T-cell-mediated immunity, which is required to control infection with Plasmodium yoelii. Consequently, IL-10 can delay the time needed to resolve this infection, leading to a higher parasite burden. While the pathways that lead to IL-10 production by CD4+ T cells are well defined, much less is known about the mediators that suppress the expression of this potent anti-inflammatory cytokine. Here, we show that the transcription factor basic helix-loop-helix family member e40 (Bhlhe40) contributes to controlling parasite burden in response to P. yoelii infection in mice. Loss of Bhlhe40 expression in mice results in higher Il10 expression, higher peak parasitemia, and a delay in parasite clearance. The observed phenotype was not due to defects in T-cell activation and proliferation or the humoral response. Nor was it due to changes in regulatory T-cell numbers. However, blocking IL-10 signaling reversed the outcome in Bhlhe40-/ - mice, suggesting that excess IL-10 production limits their ability to control the infection properly. In addition to suppressing Il10 expression in CD4+ T cells, Bhlhe40 can promote Ifng expression. Indeed, IFN-γ production by CD4+ T cells isolated from the liver was significantly affected by the loss of Bhlhe40. Lastly, Bhlhe40 deletion in T cells resulted in a phenotype similar to that observed in the Bhlhe40-/ - mice, indicating that Bhlhe40 expression in T cells contributes to the ability of mice to control infection with P. yoelii.

Th17/Treg balance is regulated by myeloid-derived suppressor cells in experimental autoimmune myocarditis.

Autoimmune myocarditis is caused by both innate and adaptive immune responses. Many studies have found that myeloid-derived suppressor cells (MDSCs) suppress T-cell responses and reduce immune tolerance, while MDSCs may serve as a key player in inflammatory responses and pathogenesis in variety of autoimmune diseases. However, research into the role of MDSCs in experimental autoimmune myocarditis (EAM) remains lacking. We discovered that the expansion of MDSCs in EAM was closely related to the severity of myocardial inflammation. At an early stage of EAM, both adoptive transfer (AT) and selective depletion of MDSCs could inhibit the expression of IL-17 in CD4+ cells and downregulate the Th17/Treg ratio, alleviating excessive inflammation of EAM myocarditis. In another experiment, in addition, MDSCs transferred after selective depletion could increase IL-17 and Foxp3 expressions in CD4+ cells, as well as the Th17/Treg ratio, contributing to the aggravation of myocardial inflammation. MDSCs promoted the Th17 cell induction under Th17-polarizing conditions in vitro but suppressed Treg expansion. These findings suggest that MDSCs play a plastic role in sustaining mild inflammation in EAM by shifting Th17/Treg balance.

Safety, immunogenicity, and protection provided by unadjuvanted and adjuvanted formulations of a recombinant plant-derived virus-like particle vaccine candidate for COVID-19 in nonhuman primates

Although antivirals are important tools to control severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, effective vaccines are essential to control the current coronavirus disease 2019 (COVID-19) pandemic. Plant-derived virus-like particle (VLP) vaccine candidates have previously demonstrated immunogenicity and efficacy against influenza. Here, we report the immunogenicity and protection induced in rhesus macaques by intramuscular injections of a VLP bearing a SARS-CoV-2 spike protein (CoVLP) vaccine candidate formulated with or without Adjuvant System 03 (AS03) or cytidine-phospho-guanosine (CpG) 1018. Although a single dose of the unadjuvanted CoVLP vaccine candidate stimulated humoral and cell-mediated immune responses, booster immunization (at 28 days after priming) and adjuvant administration significantly improved both responses, with higher immunogenicity and protection provided by the AS03-adjuvanted CoVLP. Fifteen micrograms of CoVLP adjuvanted with AS03 induced a polyfunctional interleukin-2 (IL-2)-driven response and IL-4 expression in CD4 T cells. Animals were challenged by multiple routes (i.e., intratracheal, intranasal, and ocular) with a total viral dose of 106 plaque-forming units of SARS-CoV-2. Lower viral replication in nasal swabs and bronchoalveolar lavage fluid (BALF) as well as fewer SARS-CoV-2-infected cells and immune cell infiltrates in the lungs concomitant with reduced levels of proinflammatory cytokines and chemotactic factors in the BALF were observed in animals immunized with the CoVLP adjuvanted with AS03. No clinical, pathologic, or virologic evidence of vaccine-associated enhanced disease was observed in vaccinated animals. The CoVLP adjuvanted with AS03 was therefore selected for vaccine development and clinical trials.

TGF-β1-overexpressing mesenchymal stem cells reciprocally regulate Th17/Treg cells by regulating the expression of IFN-γ.

Transforming growth factor (TGF)-β1 and mesenchymal stromal cells (MSCs) are two effective immunosuppressive agents for organ transplantation technology. This study aims to explore the molecular mechanism of TGF-β1-overexpressed MSCs on T cell immunosuppression. To achieve that, BM-MSCs were isolated from canine bone marrow, and their osteogenic differentiation and surface markers were detected. The TGF-β1 gene was transferred into lentivirus and modified MSCs (TGF-β1/MSCs) by lentivirus transfection. Furthermore, TGF-β1/MSCs were co-cultured with T cells to investigate their effect on differentiation and immune regulation. Results showed that TGF-β1/MSCs significantly downregulated the proportion of CD4+ CD8+ T cells in lymphocytes and significantly upregulated the proportion of CD4+ CD25+ T cells. Moreover, TGF-β1/MSCs significantly upregulated the expression of IL-10 in CD4+ T cells and downregulated the expression of IL-17A, IL-21, and IL-22. Meanwhile, interferon-γ (IFN-γ) neutralizing antibody blocked the effects of TGF-β1/MSCs on the differentiation inhibition of Th17. Overall, our results confirm the strong immunosuppressive effect of TGF-β1/MSCs in vitro and demonstrate that IFN-γ mediates the immunosuppressive effect of TGF-β1/MSC.

Vaccine Composition Formulated with a Novel Lactobacillus-Derived Exopolysaccharides Adjuvant Provided High Protection against Staphylococcus aureus.

A vaccine that effectively targets methicillin-resistant Staphylococcus aureus (MRSA) is urgently needed, and has been the focus of studies by numerous research groups, but with limited success to date. Recently, our team found that exopolysaccharides derived from probiotic Lactobacillus casei strain WXD030 as an adjuvant-formulated OVA could upregulate IFN-γ and IL-17 expression in CD4+ T cells. In this study, we developed a vaccine (termed rMntC-EPS) composed of S. aureus antigen MntC and Lactobacillus casei exopolysaccharides, which conferred high levels of protection against S. aureus infection. Methods: Six–eight-week-old female mice were vaccinated with purified rMntC-EPS30. The immune protection function of rMntC-EPS30 was assessed by the protective effect of rMntC-EPS30 to S. aureus-induced pulmonary and cutaneous infection in mice, bacterial loads and H&E in injury site, and ELISA for inflammation-related cytokines. The protective mechanism of rMntC-EPS30 was assessed by ELISA for IgG in serum, cytokines in the spleen and lungs of vaccinated mice. In addition, flow cytometry was used for analyzing cellular immune response induced by rMntC-EPS30. For confirmation of our findings, three kinds of mice were used in this study: IL-17A knockout mice, IFN-γ knockout mice and TCRγ/δ knockout mice. Results: rMntC-EPS30 conferred up to 90% protection against S. aureus pulmonary infection and significantly reduced the abscess size in the S. aureus cutaneous model, with clearance of the pathogen. The rMntC-EPS vaccine could induce superior humoral immunity as well as significantly increase IL-17A and IFN-γ production. In addition, we found that rMntC-EPS vaccination induced robust Th 17/γδ T 17 primary and recall responses. Interestingly, this protective effect was distinctly reduced in the IL-17A knockout mice but not in IFN-γ knockout mice. Moreover, in TCRγ/δ knockout mice, rMntC-EPS vaccination neither increased IL-17A secretion nor provided effective protection against S. aureus infection. Conclusions: These data demonstrated that the rMntC formulated with a novel Lactobacillus-derived Exopolysaccharides adjuvant provided high protection against Staphylococcus aureus. The rMntC-EPS vaccine induced γδ T cells and IL-17A might play substantial roles in anti-S. aureus immunity. Our findings provided direct evidence that rMntC-EPS vaccine is a promising candidate for future clinical application against S. aureus-induced pulmonary and cutaneous infection.

Probiotic Lactobacillus rhamnosus GG Promotes Mouse Gut Microbiota Diversity and T Cell Differentiation.

Lactic acid bacteria (LAB) are the primary genera of the intestinal flora and have many probiotic functions. In the present study, Lactobacillus rhamnosus GG (LGG) ATCC 53103 was used to treat BALB/c mice. After LGG intervention, both low and high LGG doses were shown to improve the observed OTU, Chao1, ACE, and Shannon indices, while the Simpson index decreased, demonstrating that LGG can promote intestinal microbiota abundance and diversity. Furthermore, LGG treatment increased the abundances of intestinal Firmicutes, Bacteroides and Actinomycetes while reducing that of Proteobacteria. In addition to its effect on gut the microbiota, LGG could also regulate the host immune system. In the present study, we showed that LGG could affect the percentage of CD3+ T lymphocytes in the spleens (SPLs), mesenteric lymph nodes (MLNs), Peyer’s patches (PPs) and lamina propria lymphocytes (LPLs) of mice, including total CD3+ T, CD3+CD4+ T, and CD3+CD8+ T lymphocytes. Furthermore, LGG could effectively increase the expression of Th1-type cytokines (IFN-γ) and Th2 cytokines (IL-4) in CD4+ T cells, indicating that the proportion of Th1 and Th2 cells in mice with LGG treatment was in a high equilibrium state compared to the control group. In addition, the IFN-γ/IL-4 ratio was greater than 1 in mice with LGG intervention, suggesting that LGG tends to mediate the Th1 immune response. The results of the present study also showed that LGG upregulated the expression of IL-17 in CD4+ T cells and regulated the percentage of CD4+CD25+Foxp3+ Treg cells in various secondary immunological organs, indicating that LGG may promote the balance of Th-17 and Treg cells.

Melatonin exerts immunoregulatory effects by balancing peripheral effector and regulatory T helper cells in myasthenia gravis

Myasthenia gravis (MG) is a prototypic organ-specific autoimmune disorder that, in most cases, is mainly mediated by antibodies against the acetylcholine receptor. Evidence implicates CD4+ T helper (Th) cells in the development of MG, whereas regulatory T cells (Tregs) are associated with disease resolution. Melatonin has important immunoregulatory effects in many T cell-mediated autoimmune diseases. However, there are few studies on the role of melatonin in MG. In the present study, we investigated serum melatonin levels and melatonin receptor expression in MG patients and healthy controls (HCs). We also evaluated the impact of melatonin administration on peripheral CD4+ Th cells and related cytokine production. Serum melatonin levels were lower in MG patients than in HCs, and MT1 expression was lower in PBMCs from MG patients than in those from HCs. Administration of melatonin significantly decreased Th1 and Th17 cell responses and proinflammatory cytokine production. Further investigation in vitro revealed that melatonin administration increased FoxP3 and IL-10 expression in CD4+ T cells from MG patients and enhanced the suppressive function of Tregs. These findings indicate that melatonin exerts immunoregulatory activity in MG by balancing effector and regulatory Th cell populations as well as by suppressing proinflammatory cytokine production.

RAB11FIP5-Deficient Mice Exhibit Cytokine-Related Transcriptomic Signatures.

Rab11 recycling endosomes are involved in immunological synaptic functions, but the roles of Rab11 family–interacting protein 5 (Rab11Fip5), one of the Rab11 effectors, in the immune system remain obscure. Our previous study demonstrated that RAB11FIP5 transcripts are significantly elevated in PBMCs from HIV-1–infected individuals, making broadly HIV-1–neutralizing Abs compared with those without broadly neutralizing Abs; however, the role of Rab11FiP5 in immune functions remains unclear. In this study, a RAB11FIP5 gene knockout (RAB11FIP5−/−) mouse model was employed to study the role of Rab11Fip5 in immune responses. RAB11FIP5−/− mice exhibited no perturbation in lymphoid tissue cell subsets, and Rab11Fip5 was not required for serum Ab induction following HIV-1 envelope immunization, Ab transcytosis to mucosal sites, or survival after influenza challenge. However, differences were observed in multiple transcripts, including cytokine genes, in lymphocyte subsets from envelope-immunized RAB11FIP5−/− versus control mice. These included alterations in several genes in NK cells that mirrored observations in NKs from HIV-infected humans expressing less RAB11FIP5, although Rab11Fip5 was dispensable for NK cell cytolytic activity. Notably, immunized RAB11FIP5−/− mice had lower IL4 expression in CD4+ T follicular helper cells and showed lower TNF expression in CD8+ T cells. Likewise, TNF-α production by human CD8+ T cells correlated with PBMC RAB11FIP5 expression. These observations in RAB11FIP5−/− mice suggest a role for Rab11Fip5 in regulating cytokine responses.

IKZF3/Aiolos Is Associated with but Not Sufficient for the Expression of IL-10 by CD4+ T Cells.

The expression of anti-inflammatory IL-10 by CD4+ T cells is indispensable for immune homeostasis, as it allows T cells to moderate their effector function. We previously showed that TNF-α blockade during T cell stimulation in CD4+ T cell/monocyte cocultures resulted in maintenance of IL-10-producing T cells and identified IKZF3 as a putative regulator of IL-10. In this study, we tested the hypothesis that IKZF3 is a transcriptional regulator of IL-10 using a human CD4+ T cell-only culture system. IL-10+ CD4+ T cells expressed the highest levels of IKZF3 both ex vivo and after activation compared with IL-10-CD4+ T cells. Pharmacological targeting of IKZF3 with the drug lenalidomide showed that IKZF3 is required for anti-CD3/CD28 mAb-mediated induction of IL-10 but is dispensable for ex vivo IL-10 expression. However, overexpression of IKZF3 was unable to upregulate IL-10 at the mRNA or protein level in CD4+ T cells and did not drive the transcription of the IL10 promoter or putative local enhancer constructs. Collectively, these data indicate that IKZF3 is associated with but not sufficient for IL-10 expression in CD4+ T cells.

Interleukin-33 alleviates psoriatic inflammation by suppressing the T helper type 17 immune response.

Psoriasis is a chronic inflammatory skin disease with unclear pathogenesis. Interleukin-33 (IL-33) is highly expressed in patients with psoriasis, but its role in psoriasis is unknown. The aim of this study was to investigate the possible role of IL-33 in the pathogenesis and treatment of psoriasis. IL-33 expression was determined using enzyme-linked immunosorbent assay, real-time fluorescent quantitative polymerase chain reaction and immunohistochemical staining. CD4+ T cells were sorted using magnetic beads and treated with or without IL-33. Imiquimod (IMQ) was used to induce psoriatic inflammation in mice. The frequency of immune cells was determined using flow cytometry. The cytokine level in mouse skin was measured using cytometric bead array. Our results showed that IL-33 was highly expressed in the lesional skin and serum of patients with moderate-to-severe plaque psoriasis. IL-33 inhibited the expression of IL-17 in CD4+ T cells of psoriasis patients. Subcutaneous injection of IL-33 alleviated the IMQ-induced psoriatic inflammation in mice, reduced tumor necrosis factor-α and IL-23 expression, and decreased the proportion of T helper type 17 (Th17) cells in the skin-draining lymph nodes in the mice. Our results suggest that IL-33 plays a protective role in the pathogenesis of psoriasis by suppressing Th17 cell differentiation and function. The potential therapeutic effect of IL-33 in treating psoriasis warrants further investigation.

Intermediate Monocytes in Acute Alcoholic Hepatitis Are Functionally Activated and Induce IL-17 Expression in CD4+ T Cells.

In humans, the three main circulating monocyte subsets are defined by their relative cell surface expression of CD14 and CD16. They are all challenging to study because their characteristics are strongly context specific, and this has led to a range of conflicting reports about their function, which is especially so for CD14++CD16+ (intermediate) monocytes. Ex vivo cultures are also often confounded by the concomitant use of immunosuppressive drugs. We therefore sought to characterize the phenotype and function of intermediate monocytes in the setting of acute inflammation prior to treatment in a cohort of 41 patients with acute alcoholic hepatitis (AH). Circulating intermediate monocytes were enriched in patients with AH and had an activated phenotype with enhanced expression of CCR2 and CD206 compared with healthy controls. Proinflammatory cytokine expression, including IL-1β and IL-23, was also higher than in healthy controls, but both classical (CD14++CD16-) and intermediate monocytes in AH were refractory to TLR stimulation. Compared with healthy controls, both AH monocyte subsets had greater phagocytic capacity, enhanced ability to drive memory T cell proliferation in coculture, and skewed CD4+ T cells to express an increased ratio of IL-17/IFN-γ. Furthermore, liver tissue from AH patients demonstrated an enrichment of monocytes including the intermediate subset compared with controls. These data demonstrate that intermediate monocytes are expanded, functionally activated, induce CD4+ T cell IL-17 expression, and are enriched in the liver of patients with AH.

Correction: Bcl2L12 Contributes to Th2-Biased Inflammation in the Intestinal Mucosa by Regulating CD4+ T Cell Activities.

The Th2-biased inflammation and immune deregulation play a critical role in the pathogenesis of ulcerative colitis (UC). Recent studies indicate that the Bcl2-like protein 12 (Bcl2L12) is associated with immune deregulation of UC. This study aims to investigate the role of Bcl2L12 in the induction of aberrant Th2-biased inflammation. In this study, peripheral blood samples were collected from patients with inflammatory bowel disease. The Th2 cell activities were analyzed by flow cytometry, real-time quantitative RT-PCR, and Western blotting. Mice with Bcl2L12-knockout CD4+ T cells were used in the experiments. The results showed that the expression of Bcl2L12 was detected in peripheral CD4+ T cells, which was significantly higher in UC patients than in healthy subjects. A positive correlation between the expression of Bcl2L12 and Th2 cytokines was detected in CD4+ T cells from UC patients. Naive CD4+ T cells with Bcl2L12 overexpression were prone to differentiate into Th2 cells. Mice with Bcl2L12 deficiency failed to induce the Th2-biased inflammation in the intestine. Bcl2L12 bound GATA3 to form a complex to enhance the binding between GATA3 and the Il4 promoter to enhance the expression of IL-4 in CD4+ T cells. CD4+ T cells with Bcl2L12 overexpression were resistant to apoptosis. In conclusion, the Bcl2L12 is a critical factor in the induction of aberrant Th2 polarization by upregulating Th2 responses and downregulating Th2 cell apoptosis. Bcl2L12 may be a novel therapeutic target in the management of the disorders with Th2-biased inflammation.

Cutting Edge: IL-27 Attenuates Autoimmune Neuroinflammation via Regulatory T Cell/Lag3-Dependent but IL-10-Independent Mechanisms In Vivo.

IL-27 regulates immune responses in inflammation. The underlying mechanism of IL-27 functions has long been attributed to its ability to induce IL-10 production in activated CD4 T cells. In this study, we report that Foxp3+ regulatory T cells (Tregs) are the main target cells of IL-27, mediating its immunoregulatory functions in vivo. Systemically delivered IL-27 efficiently prevents the development of experimental autoimmune encephalomyelitis, an autoimmune inflammation in the CNS. However, it failed to do so upon Treg depletion. IL-27 signaling in Tregs was necessary, as transferring Tregs deficient in IL-27Rα or Lag3, a downstream molecule induced by IL-27, was unable to protect mice from experimental autoimmune encephalomyelitis. IL-27 efficiently induced IL-10 expression in CD4 T cells in vitro; however, we found no evidence supporting IL-27-induced IL-10 induction in CD4 T cells in vivo. Taken together, our results uncover an irreplaceable contribution of Tregs during IL-27-mediated control of inflammation.

Ascl2 facilitates IL-10 production in Th17 cells to restrain their pathogenicity in inflammatory bowel disease

Inflammatory bowel disease (IBD) has been well-documented as a chronic gastrointestinal autoimmune disease, but its etiology remains to be elusive. Ascl2 (achaete-scute complex homologue 2), identified as a homologue of the Drosophila achaete-scute gene, has been shown to play an essential for the pathogenesis of autoimmune diseases and cancers. However, whether it is associated with the pathogenesis of IBD remains unclear. Here, we demonstrated that Ascl2 was greatly down-regulated in human IBD and experimental colitis. Interestingly, CD4+ T cell expression of Ascl2 was regulated by intestinal microbiota. Moreover, we revealed that Ascl2 inhibited the differentiation of Th17 cells and restrained their pathogenicity through facilitating IL-10 production. We further showed that Blimp-1 might be involved in the Ascl2-inducing IL-10 expression in CD4+ T cells under Th17 differentiating condition. Notably, lentivirus-mediated overexpression of Ascl2 remarkably alleviated the severity of 2,4,6-trinitrobenzenesulfonic acid solution (TNBS)-induced colitis in mice, with decreased level of colonic IL-17A. Our findings demonstrated an unappreciated mechanism whereby Ascl2 negatively modulates pathogenic Th17 cell differentiation via promoting IL-10 production, and alleviates intestinal inflammation. Thus, Ascl2 may serve as a novel therapeutic target of IBD.

Vitamin D (1,25(OH)2D3) induces α-1-antitrypsin synthesis by CD4+ T cells, which is required for 1,25(OH)2D3-driven IL-10

Studies to identify novel immune-regulatory functions of active vitamin D (1,25(OH)2D3) in human CD4+ T cells revealed that 1,25(OH)2D3 potently induced expression of the gene SERPINA1, encoding the anti-protease α-1-antitrypsin. We confirmed α-1-antitrypsin protein expression by 1,25(OH)2D3-treated CD4+ T cells, but not in CD8+ T cells or monocytes. α-1-Antitrypsin promotes anti-inflammatory IL-10 synthesis in other immune cell populations. We therefore investigated its immune-regulatory effects in CD4+ T cells. Plasma-derived α-1-antitrypsin drove IL-10 synthesis by CD4+ T cells, which was not dependent on anti-protease activity, but appeared to require a serum-binding factor, since this could not be achieved with recombinant protein. α-1-Antitrypsin is reported to bind complement components, which regulate T cell function. A role for this interaction was therefore probed. Plasma-derived, but not recombinant α-1-antitrypsin contained C3a. Surface Plasmon Resonance and Microscale Thermophoresis demonstrated α-1-antitrypsin binding to C3a. Addition of C3a to CD4+ T cells cultured with recombinant α-1-antitrypsin restored induction of IL-10, whereas neutralisation of C3a abrogated IL-10 induced by plasma-derived α-1-antitrypsin. To interrogate an endogenous role for the α-1-antitrypsin-C3a axis in 1,25(OH)2D3-driven CD4+ T cell IL-10 synthesis, we treated cells from healthy or α-1-antitrypsin-deficient individuals (which transcribe SERPINA1 but do not secrete protein) with 1,25(OH)2D3. A significant correlation was identified between SERPINA1 and IL10 gene expression in healthy donor CD4+ T cells, which was absent in cells from α-1-antitrypsin-deficient individuals. Therefore, α-1-antitrypsin is required for 1,25(OH)2D3-induced IL-10 expression in CD4+ T cells, interacting with C3a to drive IL-10 expression.

Bcl2L12 mediates effects of protease-activated receptor-2 on the pathogenesis of Th2-dominated responses of patients with ulcerative colitis

The immune dysregulation plays an important role in the pathogenesis of ulcerative colitis (UC). Bcl2 like protein-12 (Bcl2L12) and mast cells are involved in immune dysregulation of UC. This study aims to elucidate the role of Bcl2L12 in the contribution to the pathogenesis of T helper (Th)2-biased inflammation in UC patients. The results showed that Bcl2L12 was expressed by peripheral CD4+ T cells that was associated with Th2 polarization in UC patients. Bcl2L12 mediated the protease-activated receptor-2 (PAR2)-induced IL-4 expression in CD4+ cells. Activation of PAR2 increased expression of Bcl2L12 in CD4+ T cells. Bcl2L12 mRNA decayed spontaneously in CD4+ T cells after separated from UC patients which was prevented by activating PAR2. Bcl2L12 mediated the binding between GATA3 and the Il4 promoter in CD4+ T cells. Mice with Bcl2L12 deficiency failed to induce Th2-biased inflammation in the colon mucosa. We conclude that CD4+ T cells from UC patients expressed high levels of Bcl2L12; the latter plays an important role in the development of Th2-biased inflammation in the intestine. Bcl2L12 may be a novel therapeutic target in the treatment of Th2-biased inflammation.

Bcl2L12 Contributes to Th2-Biased Inflammation in the Intestinal Mucosa by Regulating CD4+ T Cell Activities.

The Th2-biased inflammation and immune deregulation play a critical role in the pathogenesis of ulcerative colitis (UC). Recent studies indicate that the Bcl2-like protein 12 (Bcl2L12) is associated with immune deregulation of UC. This study aims to investigate the role of Bcl2L12 in the induction of aberrant Th2-biased inflammation. In this study, peripheral blood samples were collected from patients with inflammatory bowel disease. The Th2 cell activities were analyzed by flow cytometry, real-time quantitative RT-PCR, and Western blotting. Mice with Bcl2L12-knockout CD4+ T cells were used in the experiments. The results showed that the expression of Bcl2L12 was detected in peripheral CD4+ T cells, which was significantly higher in UC patients than in healthy subjects. A positive correlation between the expression of Bcl2L12 and Th2 cytokines was detected in CD4+ T cells from UC patients. Naive CD4+ T cells with Bcl2L12 overexpression were prone to differentiate into Th2 cells. Mice with Bcl2L12 deficiency failed to induce the Th2-biased inflammation in the intestine. Bcl2L12 bound GATA3 to form a complex to enhance the binding between GATA3 and the Il4 promoter to enhance the expression of IL-4 in CD4+ T cells. CD4+ T cells with Bcl2L12 overexpression were resistant to apoptosis. In conclusion, the Bcl2L12 is a critical factor in the induction of aberrant Th2 polarization by upregulating Th2 responses and downregulating Th2 cell apoptosis. Bcl2L12 may be a novel therapeutic target in the management of the disorders with Th2-biased inflammation.

A20 ameliorates inflammatory bowel disease in mice via inhibiting NF-κB and STAT3 activation

A20 is a zinc finger protein that effectively inhibits the activation of nuclear factor (NF)-κB to downregulate the expression of tumor necrosis factor-α, interleukin (IL)-1β, and IL-17. A20 also plays a crucial role as a feedback inhibitor of the inflammatory response. Due to its inhibitory role, A20 may be useful in regulating diseases resulting from chronic inflammation and excessive pro-inflammatory cytokine production, such as colitis. Patients with colitis produce high levels of pro-inflammatory cytokines in the intestine. Therefore, this study aimed to investigate whether A20 improves experimental colitis by reducing high levels of inflammation in the intestine. An A20 overexpression vector was administered to mice by intrarectal injection after colitis induction. Histological analysis by immunohistochemistry was used to score sections of the intestine. Confocal laser scanning microscopy was used to identify the expression of IL-17 and forkhead box p (FOXP) 3 protein in spleen tissues. Protein expression induced by STAT3 and NF-κB signaling was analyzed by western blot. We found that A20 reduced the colitis activity index score and the histological score of the intestine. A20 also decreased inflammatory cytokine levels in the intestine and increased colon length. Additionally, A20 overexpression downregulated the activation of NF-kB and STAT3. A20 also reduced IL-17 expression in CD4+ T cells from spleen sections. In contrast, A20 overexpression enhanced the expression of FOXP3 in CD4+ T cells. These results suggest that A20 may inhibit the progression of colitis by decreasing inflammation via inhibition of NF-κB, phosphorylated STAT3, and IL-17.

T Cell-Derived IL-10 Impairs Host Resistance to Mycobacterium tuberculosis Infection.

Tuberculosis (TB), caused by Mycobacterium tuberculosis infection, is a leading cause of mortality and morbidity, causing ∼1.5 million deaths annually. CD4+ T cells and several cytokines, such as the Th1 cytokine IFN-γ, are critical in the control of this infection. Conversely, the immunosuppressive cytokine IL-10 has been shown to dampen Th1 cell responses to M. tuberculosis infection impairing bacterial clearance. However, the critical cellular source of IL-10 during M. tuberculosis infection is still unknown. Using IL-10 reporter mice, we show in this article that during the first 14 d of M. tuberculosis infection, the predominant cells expressing IL-10 in the lung were Ly6C+ monocytes. However, after day 21 postinfection, IL-10–expressing T cells were also highly represented. Notably, mice deficient in T cell–derived IL-10, but not mice deficient in monocyte-derived IL-10, showed a significant reduction in lung bacterial loads during chronic M. tuberculosis infection compared with fully IL-10–competent mice, indicating a major role for T cell–derived IL-10 in TB susceptibility. IL-10–expressing cells were detected among both CD4+ and CD8+ T cells, expressed high levels of CD44 and Tbet, and were able to coproduce IFN-γ and IL-10 upon ex vivo stimulation. Furthermore, during M. tuberculosis infection, Il10 expression in CD4+ T cells was partially regulated by both IL-27 and type I IFN signaling. Together, our data reveal that, despite the multiple immune sources of IL-10 during M. tuberculosis infection, activated effector T cells are the major source accounting for IL-10–induced TB susceptibility.