Galectin-1 synthesis in type 1 diabetes by different immune cell types: reduced synthesis by monocytes and Th1 cells

Galectins are a group of β-galactoside-binding mammalian lectins that play important roles in the regulation of the immune response by promoting T cell tolerance, blunting Th1 and Th17 responses and suppressing autoimmune inflammation. However, the synthesis of these molecules by different T helper (Th) subsets and in the context of human type 1 diabetes (T1D) has not yet been studied. Our results show that Th17 polarising conditions induce the synthesis of higher levels of galectin-1 compared to Th1-polarised lymphocytes. In the context of human diabetes, peripheral blood mononuclear cells (PBMCs) from T1D patients, either unstimulated or after stimulation, secreted significantly lower amounts of galectin-1 in vitro compared to healthy donors. The reduced galectin-1 synthesis observed in this autoimmune disease occurs in a dominant pro-inflammatory cytokine milieu and it is mainly due to the lower synthesis by monocytes. Surprisingly, CD4⁺ T helper cells from these patients secreted similar levels of galectin-1 compared to healthy donors, probably mediated by Th17 cytokines. In conclusion, CD4⁺ T helper lymphocytes from T1D patients produce normal levels of the immunoregulator galectin-1 but its reduced synthesis by monocytes helps to maintain a skewed pro-inflammatory response.     

Development of a unique epigenetic signature during in vivo Th17 differentiation

Activated naive CD4⁺ T cells are highly plastic cells that can differentiate into various T helper (Th) cell fates characterized by the expression of effector cytokines like IFN-γ (Th1), IL-4 (Th2) or IL-17A (Th17). Although previous studies have demonstrated that epigenetic mechanisms including DNA demethylation can stabilize effector cytokine expression, a comprehensive analysis of the changes in the DNA methylation pattern during differentiation of naive T cells into Th cell subsets is lacking. Hence, we here performed a genome-wide methylome analysis of ex vivo isolated naive CD4⁺ T cells, Th1 and Th17 cells. We could demonstrate that naive CD4⁺ T cells share more demethylated regions with Th17 cells when compared to Th1 cells, and that overall Th17 cells display the highest number of demethylated regions, findings which are in line with the previously reported plasticity of Th17 cells. We could identify seven regions located in Il17a, Zfp362, Ccr6, Acsbg1, Dpp4, Rora and Dclk1 showing pronounced demethylation selectively in ex vivo isolated Th17 cells when compared to other ex vivo isolated Th cell subsets and in vitro generated Th17 cells, suggesting that this unique epigenetic signature allows identifying and functionally characterizing in vivo generated Th17 cells.     

Arthritogenic T cells in autoimmune arthritis

Autoimmune diseases, including arthritis, often result from an imbalance between regulatory T (Treg) cells and IL-17-producing (Th17) cells. Dozens of studies in mice and humans have shed light on the pathological significance of T cells in RA. Since Th17 cells play an important role in the exacerbation of inflammation and bone destruction in joints, it has been an important issue how arthritic Th17 cells arise. Th17 cells are generated in the local inflammatory milieu via cytokines produced by macrophages or synovial fibroblasts, while it is reported that Th17 cells are generated in the gut in the presence of specific commensal bacteria. A recent report showed a pathogenic Th17 cell subset with a distinct pattern of gene expression and a potent osteoclastogenic ability are converted from Foxp3⁺ T cells in arthritic joints. Since Foxp3⁺ Treg cells contain T cells which recognize self-antigens, the fate of plastic Foxp3⁺ T cells can be a critical determinant of autoimmunity or self-tolerance. Further analysis on the molecular basis and antigen-specificity of arthritogenic Th17 cell subsets will be helpful to establish novel therapeutic approaches and clarify how self-tolerance breaks down in autoimmune arthritis.     

Wnt/β-catenin pathway promotes acute lung injury induced by LPS through driving the Th17 response in mice

T helper cell 17 (Th17), one type of CD4⁺ T cell, plays an important role in regulating the acute lung injury (ALI) inflammatory response. Recent studies showed that Wnt/β-catenin pathway could modulate the differentiation and the function of CD4⁺ T cell. However, whether Wnt/β-catenin could regulate the differentiation and function of Th17 in the development and progress of ALI induced by lipopolysaccharide (LPS) is still unknown. To test this, we used dickkopf1 (Dkk-1) to block the Wnt/β-catenin pathway and LiCl to activate the Wnt/β-catenin pathway by instillation to the murine model of ALI. Our results revealed that activation of Wnt/β-catenin pathway significantly aggravated the LPS-induced lung inflammation. Meanwhile, we observed that activation of Wnt/β-catenin pathway promoted Th17 response by analyzing CD4⁺ T cells and the related cytokines secretions. Enhanced Th17 response was responsible for the further neutrophils infiltration and pro-inflammatory cytokines production. In addition, activation of Wnt/β-catenin pathway resulted in induced expression of retinoic acid related orphan receptor-γt (RORγt) via histone acetyltransferase p300. These data suggested that Wnt/β-catenin pathway might be a potential target to treat the LPS-induced inflammation in ALI.     

Peripheral CD4CD8 cells are the activated T cells expressed granzyme B (GrB), Foxp3, interleukin 17 (IL-17), at higher levels in Th1/Th2 cytokines

Peripheral CD4⁺CD8⁺ T cells have been identified as a T cell subset existing in animals and humans. However, the characterization of CD4⁺CD8⁺ T cells, their relationship with T memory (T_M), T effector (T_E), Th1/Th2, Treg and Th-17, remain unclear. This study was to characterize the CD4⁺CD8⁺ T cells. The results from human subjects showed that activated T cells were CD4⁺CD8⁺ T cells, comprised CD4^hiCD8^lo, CD4^hiCD8^hi and CD4^loCD8^hi subsets. They expressed CD62L^hi/lo, granzyme B (GrB), CD25, Foxp3, interleukin 17 (IL-17) and the cytokines of both Th1 and Th2, and had cytolytic function. These findings suggested that CD4⁺CD8⁺ T cells had over-lap function while they kept diversity, and that T cells could be divided into two major populations: activated and inactivated. Hence, the hypotheses of Th1/Th2, Treg and Th-17 might reflect the positive/negative feedback regulation of immune system. When compared to GrB⁺CD62L^lo T effector (T_E) cells, GrB⁺CD62L^hi T central memory effector (T_CME) cells had a quicker response to virus without CD62L loss.     

Suppression of Autoimmune Retinal Inflammation by an Antiangiogenic Drug

Chronic and recurrent uveitis account for approximately 10% of legal blindness in the western world. Autoimmune uveitis is driven by activated CD4⁺ T cells that differentiate into effector T helper cells (Th1, Th2, and Th17) which release proinflammatory cytokines that damage the retina. In this study we investigated the effect of the methionine aminopeptidase 2 (MetAP2) inhibitor, Lodamin, on T cell activation and differentiation. MetAp2 is an enzyme which regulates cellular protein synthesis and is highly expressed in T cells. Lodamin was found to suppress T cell receptor (TCR) mediated T cell proliferation and reduced the production of Th1 and Th17 cells. Further, Lodamin suppressed overall inflammation in the mouse model of experimental autoimmune uveitis (EAU) by a six fold. This effect was attributed in part to a reduction in retinal proinflammatory cytokines, down regulation of MetAP2 expression in purified lymph node CD4⁺ T cells, and a general normalization of the systemic immune reaction.     

CD39+ Regulatory T cells suppress generation and differentiation of Th17 cells in human malignant pleural effusion via a LAP-dependent mechanism

Background

Both regulatory T cells (Tregs) and T helper IL-17-producing cells (Th17 cells) have been found to be involved in human malignancies, however, the possible implication of Tregs in regulating generation and differentiation of Th17 cells in malignant pleural effusion remains to be elucidated.

Methods

The numbers of both CD39⁺Tregs and Th17 cells in malignant pleural effusion and peripheral blood from patients with lung cancer were determined by flow cytometry. The regulation and mechanism of Tregs on generation and differentiation of Th17 cells were explored.

Results

Both CD39⁺Tregs and Th17 cells were increased in malignant pleural effusion when compared with blood, and the numbers of CD39⁺Tregs were correlated negatively with those of Th17 cells. It was also noted that high levels of IL-1β, IL-6, and TGF-β1 could be observed in malignant pleural effusion when compared the corresponding serum, and that pleural CD39⁺Tregs could express latency-associated peptide on their surface. When naïve CD4⁺ T cells were cocultured with CD39⁺Tregs, Th17 cell numbers decreased as CD39⁺Treg numbers increased, addition of the anti-latency-associated peptide mAb to the coculture reverted the inhibitory effect exerted by CD39⁺Tregs.

Conclusions

Therefore, the above results indicate that CD39⁺Tregs inhibit generation and differentiation of Th17 cells via a latency-associated peptide-dependent mechanism.     

Elevated Levels of CD4+CD25+FoxP3+ T Cells in Systemic Sclerosis Patients Contribute to the Secretion of IL-17 and Immunosuppression Dysfunction

Objective

Immune imbalance between regulatory T (Treg) and Th17 cells is a characteristic of systemic sclerosis (SSc). The functional heterogeneity among Treg can be elucidated by separating Treg into different subsets based on the expression of FoxP3 and CD45RA. The aim of this study was to investigate the role of Treg subsets in the immune imbalance in naïve SSc.

Methods

Peripheral blood mononuclear cells (PBMCs) of 31 SSc patients and 33 healthy controls were analyzed for the expression of CD4, CD25, CD45RA, CTLA-4, FoxP3, and IL-17 using flow cytometry. Treg immunesuppression capacity was measured in co-culture experiments. The expression of FoxP3, CTLA-4, IL-17A, and RORC mRNA was measured by real-time PCR.

Results

The frequency of CD4⁺CD25⁺FoxP3⁺ Treg cells was significantly elevated in patients with SSc (3.62±1.14 vs 1.97±0.75, p<0.001) with diminished immunosuppression capacity. In SSc, the proportion of FoxP3^highCD45RA⁻ activated Treg cells (aTreg) was decreased, the proportion of FoxP3^lowCD45RA⁻ T cells was increased, and the proportion of FoxP3^lowCD45RA⁺ resting Treg cells (rTreg) was decreased. The immune suppression capacity of aTreg and rTreg was diminished, while FoxP3^lowCD45RA⁻ T cells exhibited a lack of suppression capacity. The immune dysfunction of aTreg was accompanied by the abnormal expression of CTLA-4. Th17 cell numbers were elevated in SSc, FoxP3^lowCD45RA⁻ T cells produced IL-17, confirming their Th17 potential, which was consistent with the elevated levels of FoxP3⁺IL-17⁺ cells in SSc.

Conclusion

A decrease in aTreg levels, along with functional deficiency, and an increase in the proportion of FoxP3^lowCD45RA⁻ T cells, was the reason for the increase in dysfunctional Treg in SSc patients, potentially causing the immune imbalance between Treg and Th17 cells.     

T helper cell mediated-tolerance towards fetal allograft in successful pregnancy

Trophoblast HLA-C antigens from paternal origins, which liken the trophoblast to a semiallograft, could be presented by the maternal APCs to the specific maternal CD4+ T helper cells, which could release various cytokines in response to these alloantigens. On the basis of the cytokines produced, these cells can be classified in Th1, Th2 and Th17 cells. Th1 and Th17 cells, known to be responsible for acute allograft rejection, could be involved in miscarriage and Th2 cells together with regulatory CD4+ T cells, known to be involved in allograft tolerance, could be responsible, at least in part, for the success of pregnancy. In this review we focus the role effector CD4+ T cells Th1, Th2 and Th17 cells on the fetal allograft tolerance.     

Intracellular cytokine profile of T cells from children with acute lymphoblastic leukemia

Purpose: During an ongoing immune response, cytokines produced by T helper types 1 (Th1) and 2 (Th2) together with T cytotoxic types 1 (Tc1) and 2 (Tc2) are critical to the effectiveness of that response. Dysregulated expansion of one or the other subset may contribute to the impaired function of the T-cell-mediated immune system in cancer patients. In the present study we have investigated whether such dysregulation might exist in children with acute lymphoblastic leukemia (ALL). Methods: We analyzed 61 blood samples from 45 children with B cell precursor ALL and 16 healthy children. Interleukin(IL)-2, IL-4, and interferon γ (IFNγ) production of their respective purified CD4⁺ and CD8⁺ T cells were assessed at the single-cell level by intracellular-cytokine-staining flow cytometry. Results: At the time of diagnosis, IL-2-producing cell populations in CD4⁺ and CD8⁺ T cells were reduced below the normal range in 31 of 44 (70.5%) and 23 of 38 (60.5%) cases respectively. Similarly, IFNγ-producing cell populations in CD4⁺ and CD8⁺ T cells decreased in 17 of 44 (38.6%) and 18 of 38 (47.4%) cases respectively. Conversely cell populations capable of IL-4 production in CD4⁺ and CD8⁺ T cell subsets were increased in 13 of 30 (43.3%) and 15 of 30 (50.0%) cases respectively. Therefore, the Th1-to-Th2 and Tc1-to-Tc2 ratios (1.6 ± 2.2 and 7.7 ± 6.7 respectively) were significantly lower in peripheral blood T cells of ALL patients (n = 30) than those (6.0 ± 2.9 and 20.1 ± 10.3 respectively) in 15 healthy controls (P < 0.0001). Although both CD45RA⁺/CD4⁺ and CD45RA⁺/CD8⁺ cells significantly increased in 43 ALL patients (P < 0.05), there existed no apparent correlation between CD45 isoform expression and cytokine (IL-2 and IFNγ) production. Interestingly, the ability to produce both IL-2 and IFNγ was recovered in 8 cases examined, after complete remission had been achieved. Conclusion: These observations suggest that, in both CD4⁺ and CD8⁺ T cells of ALL patients, there is a dysregulation in the functionality of Th1 (Tc1) and Th2 (Tc2) cells with a gross reduction of Th1 (Tc1) cell populations and an expansion in Th2 (Tc2). Received: 12 November 1999 / Accepted: 2 January 2000     

p38α Protein Negatively Regulates T Helper Type 2 Responses by Orchestrating Multiple T Cell Receptor-associated Signals

Mitogen-activated protein kinase p38α is a critical regulator of certain inflammatory diseases. However, its role in T helper type 2 (Th2) responses and allergic inflammation remains unknown. Here we show an increase in the production of interleukin-4 (IL-4) in p38α^−/− CD4⁺ T cells in response to antigen stimulation. p38α-deficient naïve CD4⁺ T cells preferentially differentiate into Th2 cells through increased endogenous production of IL-4. Consistent with those results, we also observed decreased expression of p38α during T helper cell differentiation. Furthermore, deficiency of p38α alters the balance in the expression of NFATc1 and NFATc2 under steady-state conditions and enhances the expression and nuclear translocation of NFATc1 in CD4⁺ T cells upon antigen stimulation. Knockdown of NFATc1 significantly inhibits Th2 differentiation in p38α^−/− T cells but not in p38α^+/− T cells. p38α deficiency also inhibits the activation of Akt but enhances the activation of ERK in response to T cell receptor engagement without impacting IL-2/Stat5 signaling. In a model of ovalbumin-induced acute allergic airway inflammation, mice with induced deletion of p38α show elevated serum ovalbumin-specific IgE level, increased infiltration of eosinophils, and higher concentrations of Th2 cytokines including IL-4 and IL-5 in the bronchoalveolar lavage fluid relative to control mice. Taken together, p38α regulates multiple T cell receptor-associated signals and negatively influences Th2 differentiation and allergic inflammation.     

CD26 Expression on T Helper Populations and sCD26 Serum Levels in Patients with Rheumatoid Arthritis

We studied dipeptidyl peptidase IV (DPP-IV, CD26) expression in different T helper cells and serum soluble DPP-IV/sCD26 levels in rheumatoid arthritis (RA) patients, correlated these with disease activity score (DAS), and examined how they were affected by different therapies, conventional or biological (anti-TNF, anti-CD20 and anti-IL6R or Ig-CTLA4). The percentage of CD4⁺CD45R0⁺CD26^- cells was greatly reduced in patients (up to 50%) when compared with healthy subjects. Three other subsets of CD4 cells, including a CD26high Th1-associated population, changed variably with therapies. Data from these subsets (frequency and staining density) significantly correlated with DAS28 or DAS28 components but different in each group of patients undergoing the different therapies. Th17 and Th22 subsets were implicated in RA as independent CCR4⁺ and CCR4^- populations each, with distinct CD26 expression, and were targeted with varying efficiency by each therapy. Serum DPP-IV activity rather than sCD26 levels was lower in RA patients compared to healthy donors. DPP-IV and sCD26 serum levels were found related to specific T cell subsets but not to disease activity. We conclude that, according to their CD26 expression, different cell subsets could serve to monitor RA course, and an uncharacterized T helper CD26^- subset, not targeted by therapies, should be monitored for early diagnosis.     

Anaphylatoxins orchestrate Th17 response via interactions between CD16+ monocytes and pleural mesothelial cells in tuberculous pleural effusion

The complement system is activated in tuberculous pleural effusion (TPE), with increased levels of the anaphylatoxins stimulating pleural mesothelial cells (PMCs) to secrete chemokines, which recruit nonclassical monocytes to the pleural cavity. The differentiation and recruitment of naive CD4⁺ T cells are induced by pleural cytokines and PMC-produced chemokines in TPE. However, it is unclear whether anaphylatoxins orchestrate CD4⁺ T cell response via interactions between PMCs and monocytes in TPE. In this study, CD16⁺ and CD16^- monocytes isolated from TPE patients were cocultured with PMCs pretreated with anaphylatoxins. After removing the PMCs, the conditioned monocytes were cocultured with CD4⁺ T cells. The levels of the cytokines were measured in PMCs and monocyte subsets treated separately with anaphylatoxins. The costimulatory molecules were assessed in conditioned monocyte subsets. Furthermore, CD4⁺ T cell response was evaluated in different coculture systems. The results indicated that anaphylatoxins induced PMCs and CD16⁺ monocytes to secrete abundant cytokines capable of only inducing Th17 expansion, but Th1 was feeble. In addition, costimulatory molecules were more highly expressed in CD16⁺ than in CD16⁻ monocytes isolated from TPE. The interactions between monocytes and PMCs enhanced the ability of PMCs and monocytes to produce cytokines and that of monocytes to express HLA-DR, CD40, CD80 and CD86, which synergistically induced Th17 expansion. In the above process, anaphylatoxins enhanced the interactions between monocytes and PMCs by increasing the level of the cytokines IL-1β, IL-6, IL-23 and upregulating the phenotype of CD40 and CD80 in CD16⁺ monocytes. Collectively, these data indicate that anaphylatoxins play a central role in orchestrating Th17 response mainly via interactions between CD16⁺ monocytes and PMCs in TPE.