Cytokine mediators of Th17 function

Pretransplant, Th17 dominant alloreactivity in highly sensitized kidney transplant candidates

Introduction

Sensitization to donor human leukocyte antigen (HLA) molecules prior to transplantation is a significant risk factor for delayed access to transplantation and to long-term outcomes. Memory T cells and their cytokines play a pivotal role in shaping immune responses, thereby increasing the risk of allograft rejection among highly sensitized patients. This study aims to elucidate the precise contribution of different CD4+ memory T cell subsets to alloreactivity in highly sensitized (HS) kidney transplant recipients.

Methods and results

Stimulation of peripheral blood mononuclear cells (PBMC) with various polyclonal stimulating agents to assess non-specific immune responses revealed that HS patients exhibit elevated immune reactivity even before kidney transplantation, compared to non-sensitized (NS) patients. HS patients' PBMC displayed higher frequencies of CD4+ T cells expressing IFNγ, IL4, IL6, IL17A, and TNFα and secreted relatively higher levels of IL17A and IL21 upon stimulation with PMA/ionomycin. Additionally, PBMC from HS patients stimulated with T cell stimulating agent phytohemagglutinin (PHA) exhibited elevated expression levels of IFNγ, IL4 and, IL21. On the other hand, stimulation with a combination of resiquimod (R848) and IL2 for the activation of memory B cells demonstrated higher expression of IL17A, TNFα and IL21, as determined by quantitative real-time PCR. A mixed leukocyte reaction (MLR) assay, employing third-party donor antigen presenting cells (APCs), was implemented to evaluate the direct alloreactive response. HS patients demonstrated notably higher frequencies of CD4+ T cells expressing IL4, IL6 and IL17A. Interestingly, APCs expressing recall HLA antigens triggered a stronger Th17 response compared to APCs lacking recall HLA antigens in sensitized patients. Furthermore, donor APCs induced higher activation of effector memory T cells in HS patients as compared to NS patients.

Conclusion

These results provide an assessment of pretransplant alloreactive T cell subsets in highly sensitized patients and emphasize the significance of Th17 cells in alloimmune responses. These findings hold promise for the development of treatment strategies tailored to sensitized kidney transplant recipients, with potential clinical implications.

Normalized circulating Tfh and Th17 associates with improvement in myasthenia gravis treated with ofatumumab

Objective

To assess the effect of B cell depletion therapy (BCDT) on circulating T follicular helper (cTfh) and circulating T helper 17 (cTh17) cells and its relation to clinical improvement in patients with myasthenia gravis (MG).

Methods

28 anti-AchR positive MG patients treated with ofatumumab and 28 healthy controls (HCs) were included. Frequencies of cTfh and cTh17 cells were monitored by flow cytometry at baseline and 4, and 12 weeks after the initial dose ofatumumab. Serum cytokines associated with cTfh and cTh17, including IL-6, IL-21, and IL-17, were also analyzed.

Results

The frequency of cTfh and cTh17 significantly increased in MG patients compared with HCs. Additionally, elevated levels of both T-cell subsets correlated with MG severity. During the follow-up, cTfh and cTh17 return to normal after BCDT. Furthermore, the decrease in cTfh and cTh17 was associated with MG scores improvement over time. Notably, cTfh- and cTh17-related cytokines, including IL-6, IL-21, and IL-17, exhibited a marked decrease following ofatumumab therapy.

Conclusions

Abnormal expansion of cTfh and cTh17 cells may be key features in the immunopathology of MG. Their levels returned to normal after BCDT, which was closely correlated with clinical amelioration. This result suggests that these two T-cell subsets may be targets for BCDT treatment of MG.

Molecular Mimicry of the Rheumatoid Arthritis-Related Immunodominant T-Cell Epitope within Type II Collagen (CII260-270) by the Bacterial L-Asparaginase

The etiology of most autoimmune diseases, including rheumatoid arthritis (RA), remains unclear. Both genetic and environmental factors are believed to be involved in pathogenesis. Molecular mimicry is considered one of the mechanisms for the occurrence of autoimmune diseases. The aim of the study was to determine whether the bacterial peptide L-ASNase67-81, which mimics the immunodominant T-cell epitope CII259-273, can induce T-cell reactivity in blood samples from RA patients and healthy subjects through molecular mimicry. Using bioinformatic molecular modeling methods, we first determined whether the L-ASNase67-81 peptide binds to the HLA-DRB1*04:01 molecule and whether the formed MHCII–peptide complex interacts with the corresponding T-cell receptor. To validate the obtained results, leukocytes isolated from early RA patients and healthy individuals were stimulated in vitro with L-ASNase67-81 and CII259-273 peptides as well as with bacterial L-asparaginase or human type II collagen (huCII). The activated T cells (CD4+CD154+) were analyzed by flow cytometry (FACS), and the levels of cytokines produced (IL-2, IL-17A/F, and IFN-γ) were measured by ELISA. Our in silico analyses showed that the bacterial peptide L-ASNase67-81 binds better to HLA-DRB1*04:01 compared to the immunodominant T-cell epitope CII259-273, mimicking its structure and localization in the binding groove of MHCII. Six contact points were involved in the molecular interaction of the peptide with the TCR. FACS data showed that after in vitro stimulation with the L-ASNase67-81 peptide, the percentage of activated T cells (CD154⁺CD4⁺) was significantly increased in both cell cultures isolated from ERA patients and those isolated from healthy individuals, as higher values were observed for the ERA group (9.92 ± 0.23 vs. 4.82 ± 0.22). Furthermore, the ELISA assays revealed that after stimulation with L-ASNase67-81, a significant increase in the production of the cytokines IL-2, IL-17A/F, and IFN-γ was detected in the group of ERA patients. Our data showed that the bacterial L-ASNase67-81 peptide can mimic the immunodominant T-cell epitope CII259-273 and activate HLA-DRB1*04:01-restricted T cells as well as induce cytokine production in cells isolated from ERA patients. These results are the first to demonstrate that a specific bacterial antigen could play a role in the pathogenesis of RA, mimicking the immunodominant T-cell epitope from type II collagen.

The Role of Different Lymphoid Cell Populations in Preeclampsia Pathophysiology

Preeclampsia (PE), new-onset hypertension during pregnancy, affects up to 10% of pregnancies worldwide. Despite being the leading cause of maternal and fetal morbidity and mortality, PE has no cure beyond the delivery of the fetal-placental unit. Although the exact pathogenesis of PE is unclear, there is a strong correlation between chronic immune activation; intrauterine growth restriction; uterine artery resistance; dysregulation of the renin-angiotensin system. Which contributes to renal dysfunction; and the resulting hypertension during pregnancy. The genesis of PE is thought to begin with insufficient trophoblast invasion leading to reduced spiral artery remodeling, resulting in decreased placental perfusion and thereby causing placental ischemia. The ischemic placenta releases factors that shower the endothelium and contribute to peripheral vasoconstriction and chronic immune activation and oxidative stress. Studies have shown imbalances in proinflammatory and anti-inflammatory cell types in women with PE and in animal models used to examine mediators of a PE phenotype during pregnancy. T cells, B cells, and natural killer cells have all emerged as potential mediators contributing to the production of vasoactive factors, renal and endothelial dysfunction, mitochondrial dysfunction, and hypertension during pregnancy. The chronic immune activation seen in PE leads to a higher risk for other diseases, such as cardiovascular disease, CKD, dementia during the postpartum period, and PE during a subsequent pregnancy. The purpose of this review is to highlight studies demonstrating the role that different lymphoid cell populations play in the pathophysiology of PE. Moreover, we will discuss treatments focused on restoring immune balance or targeting specific immune mediators that may be potential strategies to improve maternal and fetal outcomes associated with PE.

Inflammasome Contribution to the Activation of Th1, Th2, and Th17 Immune Responses

Inflammasomes are cytosolic polyprotein complexes formed in response to various external and internal stimuli, including viral and bacterial antigens. The main product of the inflammasome is active caspase 1 which proteolytically cleaves, releasing functional interleukin-1 beta (IL-1β) and interleukin-18 (IL-18). These cytokines play a central role in shaping immune response to pathogens. In this review, we will focus on the mechanisms of inflammasome activation, as well as their role in development of Th1, Th2, and Th17 lymphocytes. The contribution of cytokines IL-1β, IL-18, and IL-33, products of activated inflammasomes, are summarized. Additionally, the role of cytokines released from tissue cells in promoting differentiation of lymphocyte populations is discussed.

Impact of HIV-ART on the restoration of Th17 and Treg cells in blood and female genital mucosa

The aim of this study was to evaluate the effectiveness of antiretroviral treatment (ART) on the proportion and functions of Th17 and Treg cells in peripheral blood and female genital tract (FGT) respectively. To this aim, samples from 41 HIV-neg, 33 HIV+ ART-naïve and 32 HIV+ ART+ subjects were obtained. In peripheral blood, altered Th17 and Th17/Treg proportions were normalized in HIV+ ART+, but certain abnormal Treg and activated T-cell proportions were still observed. In FGT, abnormal patterns of secretion for Th17-related cytokines were observed in cervical mononuclear cells (CMCs) from HIV+ women, even in those from HIV+ ART+, compared to the HIV-neg group. Moreover, these altered patterns of secretion were associated with diminished levels of CXCL5 and CXCL1 chemokines and with an immunoregulatory skew in the CCL17/CCL20 ratio in ectocervix samples of these women. Finally, ART did not restore proportions of Th17-precursor cells with gut-homing potential in PBMCs, and positive correlations between these cells and the levels of IL-17F and IL-21 production by CMCs may suggest that a better homing of these cells to the intestine could also imply a better restoration of these cells in the female genital tract. These results indicate that antiretroviral treatment did not restore Th17-related immune functions completely at the female mucosal level.

Mechanisms of Cholera Toxin in the Modulation of TH17 Responses

Numerous studies have shown that TH17 cells and their signature cytokine IL-17A are critical to host defense against various bacterial and fungal infections. The protective responses mediated by TH17 cells and IL-17A include the recruitment of neutrophils, release of antimicrobial peptides and chemokines, and enhanced tight junction of epithelial cells. Due to the importance of TH17 cells in infections, efforts have been made to develop TH17-based vaccines. The goal of vaccination is to establish a protective immunological memory. Most currently approved vaccines are antibody-based and have limited protection against stereotypically different strains. Studies show that T-cell-based vaccines may overcome this limitation and protect hosts against infection of different strains. Two main strategies are used to develop TH17 vaccines: identification of TH17-specific antigens and TH17-skewing adjuvants. Studies have revealed that cholera toxin (CT) induces a potent Th17 response following vaccination. Antigen vaccination along with CT induces a robust TH17 response, which is sometimes accompanied by TH1 responses. Due to the toxicity of CT, it is hard to apply CT in a clinical setting. Thus, understanding how CT modulates TH17 responses may lead to the development of successful TH17-based vaccines.

Regulatory role of natural killer T cells in diabetes

Type 1 and type 2 diabetes are growing public health problems. Despite having different pathophysiologies, both diseases are associated with defects in immune regulation. Invariant natural killer T (iNKT) cells are innate-like T cells that recognize glycolipids presented by CD1d. These cells not only play a key role in the defense against pathogens, but also exert potent immunoregulatory functions. The regulatory role of iNKT cells in the prevention of type 1 diabetes has been demonstrated in murine models and analyzed in diabetic patients. The decreased frequency of iNKT cells in non-obese diabetic mice initially suggested the regulatory role of this cell subset. Increasing the frequency or the activation of iNKT cells with agonists protects non-obese diabetic mice from the development of diabetes. Several mechanisms mediate iNKT regulatory functions. They can rapidly produce immunoregulatory cytokines, interleukin (IL)-4 and IL-10. They induce tolerogenic dendritic cells, thereby inducing the anergy of autoreactive anti-islet T cells and increasing the frequency of T regulatory cells (Treg cells). Synthetic agonists are able to activate iNKT cells and represent potential therapeutic treatment in order to prevent type 1 diabetes. Growing evidence points to a role of immune system in glucose intolerance and type 2 diabetes. iNKT cells are resident cells of adipose tissue and their local and systemic frequencies are reduced in obese patients, suggesting their involvement in local and systemic inflammation during obesity. With the discovery of potential continuity between type 1 and type 2 diabetes in some patients, the role of iNKT cells in these diseases deserves further investigation.

Construction and Functional Characterization of a Fusion Protein Interleukin-21/Immunoglobulin for Long-Term In Vivo Biodisponibility

Interleukin (IL)-21 has been intensively studied for use in therapy of autoimmune diseases, cancers, and chronic viruses due to its immunomodulatory properties, especially on CD4(+) and CD8(+) T cells and natural killer (NK) cells. The objective of this study was to produce an optimized form of IL-21 with improved stability. Plasmids encoding the murine IL-21 alone (pIL-21) or IL-21 genetically fused to portions from mouse IgG3 (pIL-21/Ig) were constructed, and the efficiency of expression, protein kinetics, biodisponibility, and function were analyzed. The genetic constructions of pIL-21 and pIL-21/Ig were transfected into HEK 293 cells, and significant levels of functional IL-21 were obtained. The amino acid of murine IL-21 and IgG3 cloned showed 100% identity with correspondent published sequences. At 24 h of incubation, increased levels of IL-21 were detected in the supernatants of pIL-21. At 72 h of culture, the levels of IL-21 in the supernatant of cells transfected with pIL-21/Ig were significantly higher than those secreted by pIL-21-transfected cells. Furthermore, the data showed that our chimeric IL-21/Ig present improved systemic disponibility in BALB/c mice and conserved the intrinsic ability to increase the frequency of CD4(+) T cells, NKT cells, and CD8(+) T cells.

Impact of nicotine on the interplay between human periodontal ligament cells and CD4+ T cells

Periodontitis is a common infectious disease associated with destruction of periodontal ligaments and alveolar bones. CD4(+) T cell-mediated immune response is involved in the progression of periodontitis. Tobacco consumption increases the risk of periodontal disease. However, the impact of nicotine on the interaction between human periodontal ligament (PDL) cells and CD4(+) T cells remains unrevealed. Our study aims to investigate the effect of nicotine on PDL cells and the cocultured CD4(+) T cells. The PDL cell cultures were established by explants from healthy individuals, exposed to nicotine or α-bungarotoxin (α-BTX), and incubated solely or in combination with CD4(+) T cells. Afterwards, cell viability, secreted cytokines, and matrix metalloproteinases (MMPs) were evaluated. In monoculture of PDL cells, nicotine dramatically repressed cell viability and increased apoptosis. Meanwhile, α-BTX largely reversed the nicotine-induced apoptosis and increased viability of PDL cells. Compared with the monoculture, MMP-1, MMP-3, interleukin (IL)-1β, IL-6, IL-17, and IL-21 in supernatant of cocultures were markedly elevated after treatment with nicotine. Moreover, α-BTX significantly attenuated nicotine-triggered production of these components either in mono- or co-cultures. In addition, PDL cell-derived CXCL12 following nicotine treatment recruited CD4(+) T cells. Above all, nicotine deteriorated periodontitis partially by promoting PDL cell-CD4(+) T cell-mediated inflammatory response and matrix degradation.

Dehydrodiconiferyl alcohol (DHCA) modulates the differentiation of Th17 and Th1 cells and suppresses experimental autoimmune encephalomyelitis

Dehydrodiconiferyl alcohol (DHCA), originally isolated from the stems of Cucurbita moschata, has previously been shown to exhibit anti-adipogenic and anti-lipogenic effects in 3T3-L1 cells and primary mouse embryonic fibroblasts (MEFs) (Lee et al., 2012). Here, we investigated whether synthetic DHCA could suppress the CD4 T helper 17 (Th17)-mediated production of the interleukin (IL)-17 protein. The results from RT-qPCR suggest that DHCA-mediated down-regulation of IL-17 occurred at the transcriptional level by suppressing the expression of RAR-related orphan receptor (ROR)γt, the master transcription factor involved in the differentiation of Th17 cells. Furthermore, such inhibition was mediated by the suppression of NF-κB activity. DHCA also inhibited the Th1-mediated production of interferon (IFN) γ by controlling the expression of a key transcription factor known to regulate the production of this cytokine, T-bet. In the mouse experimental autoimmune encephalomyelitis (EAE) model, DHCA showed significant therapeutic effects by inhibiting the infiltration of immune cells into the spinal cords, decreasing the differentiation of pathogenic Th17 and Th1 cells, suppressing the expression of various pro-inflammatory cytokines, and eventually ameliorating the clinical symptoms of EAE mice. Taken together, our data indicate that DHCA may be a potential candidate as an agent for the control of Th17 and Th1-mediated inflammatory diseases.

Regulatory Role of Natural Killer T Cells in Diabetes

Type 1 and type 2 diabetes are growing public health problems. Despite having different pathophysiologies, both diseases are associated with defects in immune regulation. Invariant natural killer T (iNKT) cells are innate-like T cells that recognize glycolipids presented by CD1d. These cells not only play a key role in the defense against pathogens, but also exert potent immunoregulatory functions. The regulatory role of iNKT cells in the prevention of type 1 diabetes has been demonstrated in murine models and analyzed in diabetic patients. The decreased frequency of iNKT cells in non-obese diabetic mice initially suggested the regulatory role of this cell subset. Increasing the frequency or the activation of iNKT cells with agonists protects non-obese diabetic mice from the development of diabetes. Several mechanisms mediate iNKT regulatory functions. They can rapidly produce immunoregulatory cytokines, interleukin (IL)-4 and IL-10. They induce tolerogenic dendritic cells, thereby inducing the anergy of autoreactive anti-islet T cells and increasing the frequency of T regulatory cells (Treg cells). Synthetic agonists are able to activate iNKT cells and represent potential therapeutic treatment in order to prevent type 1 diabetes. Growing evidence points to a role of immune system in glucose intolerance and type 2 diabetes. iNKT cells are resident cells of adipose tissue and their local and systemic frequencies are reduced in obese patients, suggesting their involvement in local and systemic inflammation during obesity. With the discovery of potential continuity between type 1 and type 2 diabetes in some patients, the role of iNKT cells in these diseases deserves further investigation.

Interleukin-17 and interleukin-22 promote tumor progression in human nonmelanoma skin cancer

Interleukin-17 (IL-17) and IL-22 have been reported to play critical roles in autoimmunity and inflammation but information about their role in cancer is limited. In this study, we investigated the role of IL-17 and IL-22 in the progression of human skin basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC). We found that both tumor types are infiltrated with an high number of IL-17(+) and IL-22(+) T lymphocytes, as demonstrated by immunohistochemistry and by FACS analysis performed on peritumoral T-cell lines isolated from skin biopsies. In vitro studies demonstrated that proliferation and migration of the BCC- and SCC-cell lines M77015 and CAL27 were increased by IL-17 and IL-22. Moreover, IL-17, alone or in combination with TNF-α, was able to induce the production of two cytokines important for tumor progression, IL-6 and IL-8, in CAL27. We also showed that IL-17 upregulated NF-κB signaling, while IL-22 activated the STAT3 pathway and the antiapoptotic AKT protein in M77015 and CAL27. Finally, in vivo experiments demonstrated that IL-17 and IL-22 enhanced tumor growth in nude mice injected with CAL27. Altogether, our findings indicate that high levels of IL-22 and IL-17 in the BCC and SCC microenvironment promote tumor progression.

Host candidate gene polymorphisms and associated clearance of P. falciparum amodiaquine and fansidar resistance mutants in children less than 5 years in Cameroon

BACKGROUND

In this post-hoc analysis, we determined the influence of single nucleotide polymorphisms in host candidate immune genes on the outcome of drug resistant malaria in Cameroon.

METHODS

Human DNA from 760 patients from a previous clinical trial was subjected to mass spectrometry-based single nucleotide polymorphism (SNP) genotyping. Allele frequencies of candidate immune genes were calculated for 62 SNPs on 17 human chromosomes for their possible involvement in clearance of drug-resistant parasites with the triple mutations of pfcrt76T, pfmdr86Y, and pfmdr1246Y (TY) and pfdhfr51I, pfdhfr59R, pfdhfr108N, and pfdhps437G (IRNG) which were determined by dotblot or PCR-restriction analysis. Differences in SNP frequencies and association analysis were carried out by comparing Chi-square odds ratios (ORs) and stratified by Mantel-Haenzel statistics. An adjusted P value (OR) <0·0008 was considered significant.

RESULTS

Post-treatment drug failure rates were amodiaquine (36·4%); sulpadoxine/pyrimethamine-amodiaquine combination (15·4%); and sulphadoxine/pyrimethamine (18·1%). SNPs in IL22, IL-4R1, and CD36 appeared to have been associated with clearance of resistant parasites [p  =  0·017, OR (C allele):1·44, 95% CI (OR): 1·06-1·95]; [P  =  0·014, OR  =  1·31, 95% CI (OR): 1·07-1·83]; [P  =  5·78×10(-5), OR  =  0·27, 95%CI (OR): 0·13-0·54], respectively, with high fever (>39°C for 48 hours) [IL-22, P  =  0·01, OR  =  1·5, 95% CI (OR): 1·8-2·1] and also in high frequency among the Fulani participants [P  =  0·006, OR  =  1·83, 95% CI (OR): 1·11-3·08)]. The CD36-1264 null allele was completely absent in the northern population.

CONCLUSION

Independent association of SNPs in IL22 and IL-4 with clearance of amodiaquine- and sulphadoxine/pyrimethamine-resistant parasites did not reach statistical significance, but may suggest that not all drug-resistant mutants are adversely affected by the same immune-mediated mechanisms of clearance.

Tumor-associated antigen/IL-21-transduced dendritic cell vaccines enhance immunity and inhibit immunosuppressive cells in metastatic melanoma

Dendritic cell (DC)-based vaccine approaches are being actively evaluated for developing immunotherapeutic agents against cancers. In this study, we investigated the use of engineered DCs expressing transgenic tumor-associated antigen hgp100 and the regulatory cytokine interleukin-21, namely DC-hgp100/mIL-21, as a therapeutic vaccine against melanoma. Tumor-bearing mice were injected intratumorally with transgenic DCs followed by three booster injections. Transgenic DC-hgp100/mIL-21 showed significant reduction in primary tumor growth and metastasis compared with DC-hgp100 alone and DC-mIL-21 alone. In vivo depletion of specific immune cell types (CD8(+) T, CD4(+) T and Natural killer (NK)-1.1(+) cells) effectively blocked the protective effect of this combinational vaccine. In adoptive transfer experiments, a survival rate of nearly 90% was observed at 60 days post-tumor inoculation for the combinational vaccine group. In contrast, all mice in the DC-hgp100 and DC-mIL-21-only groups died within 43-46 days after tumor challenge. Considerably increased levels of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, granulocyte macrophage colony-stimulating factor (GM-CSF) and cytotoxic T lymphocytes (CTLs) were detected with the combination vaccine group compared with other individual treatment groups. In comparison with the DC-hgp100 or mIL-21 groups, the combinational DC-hgp100/mIL-21 vaccine also drastically suppressed the myeloid-derived suppressor cells (MDSCs) and T-regulatory (Treg) cell populations. Our findings suggest that a combinational DC- and gene-based hgp100 and mIL-21 vaccine therapy strategy warrants further evaluation as a clinically relevant cancer vaccine approach for human melanoma patients.

Dynamic Changes of Treg and Th17 Cells and Related Cytokines Closely Correlate With the Virological and Biochemical Response in Chronic Hepatitis B Patients Undergoing Nucleos(t)ide Analogues Treatment

BACKGROUND

The restoration of HBV-specific T-cell response during antiviral therapy is associated with CD4+T-cell activity. Treg cells and Th17 cells are subtypes of CD4+T cell. However, it has remained unknown how the Treg and Th17 cells and their associated cytokines affect nucleos(t)ide analogues (NA) antiviral efficacy.

OBJECTIVES

The aim of the present study was to provide a new insight to evaluate the NA antiviral therapy for patients with chronic hepatitis B (CHB).

PATIENTS AND METHODS

Forty-four CHB patients hospitalized between July 2010 and August 2011 were enrolled in this study. They were received NA (entecavir, lamivudine and adefovir) treatment for 14.42 ± 13.08 weeks, and the peripheral blood was collected. The frequencies of Treg and Th17 cells were detected by flow cytometric analysis, and the levels of IL-10, TGF-β1, IL-17 and IL-23 were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In complete and partial-responders, Treg cells frequencies and IL-10, TGF-β1, IL-23 levels were all decreased significantly after NA therapy, while Th17 cells and the IL-17 levels were increased slightly. Treg/Th17 ratio was only dramatically declined in complete-responders. But there was no significant difference in non-responders. Either HBV DNA decreased by at least 2 log copies /mL or ALT turned to normal level, Treg cells frequencies and IL-10, TGF-β1, IL-23 levels were significantly reduced. Meanwhile, Treg cells were positively correlated with HBV DNA and ALT.

CONCLUSIONS

The changes of Treg and Th17 cells and their associated cytokines were related to virological and biochemical responses.

IL-17 protects T cells from apoptosis and contributes to development of ALPS-like phenotypes

In autoimmune/lymphoproliferative syndrome (ALPS), defective Fas death receptor function causes lymphadenomegaly/splenomegaly, the expansion of T-cell receptor αβ(+) CD4/CD8 double-negative T cells, and frequent development of hematologic autoimmunity. Dianzani autoimmune lymphoproliferative disease (DALD) has a similar phenotype but lacks the expansion of double-negative T cells. This work shows that patients with ALPS and DALD have high serum levels of interleukin 17A (IL-17A), IL-17F, and IL-17AF, which are involved in several autoimmune diseases, and that their T cells show increased secretion of these cytokines upon activation in vitro. The following data indicate that these cytokines may contribute to ALPS and DALD: (1) recombinant IL-17A and IL-17F significantly inhibit Fas-induced cell death in Fas-sensitive T cells from healthy donors; (2) this inhibitory effect is also induced by the patients' serum and is reversed by anti-IL-17A antibodies; (3) IL-17A neutralization substantially increases Fas-induced cell death in T cells from ALPS and DALD patients in vitro; and (4) treatment with anti-IL-17A antibodies ameliorates the autoimmune manifestations and, at a lesser extent, the lymphoproliferative phenotype and prolongs survival in MRLlpr/lpr mice, which are an animal model of ALPS. These data suggest that IL-17A and IL-17F could be targeted therapeutically to improve Fas function in ALPS and DALD.

Cholera toxin directly enhances IL-17A production from human CD4+ T cells

The significance of Th17 cells and IL-17A signaling in host defense and disease development has been demonstrated in various infection and autoimmune models. Additionally, the generation of Th17 cells is highly influenced by microbes. However, the specific bacterial components capable of shaping Th17 responses have not been well defined. The goals of this study were to understand how a bacterial toxin, cholera toxin (CT), modulates Th17-dominated response in isolated human CD4(+) T cells, and what are the mechanisms associated with this modulation. CD4(+) cells isolated from human peripheral blood were treated with CT. The levels of cytokine production and specific Th cell responses were determined by ELISA, Luminex assay, and flow cytometry. Along with the decreased production of other proinflammatory cytokines (IFN-γ, TNF-α, and IL-2), we found that CT could directly enhance the IL-17A production through a cAMP-dependent pathway. This enhancement is specific for IL-17A but not for IL-17F, IL-22, and CCL20. Interestingly, CT could increase IL-17A production only from Th17-committed cells, such as CCR6(+)CD4(+) T cells and in vitro-differentiated Th17 cells. Furthermore, we also demonstrated that this direct effect occurs at a transcriptional level because CT stimulates the reporter activity in Jurkat and primary CD4(+) T cells transfected with the IL-17A promoter-reporter construct. This study shows that CT has the capacity to directly shape Th17 responses in the absence of APCs. Our findings highlight the potentials of bacterial toxins in the regulation of human Th17 responses.

Molecular mechanisms and cell targets of Th17 cells in the gastrointestinal tract: an innate sense of adaptivity

T-helper (TH) 17 activation is crucial for protective immune responses against bacteria and fungi at mucosal surfaces, but it can also be implicated in the pathogenesis of several autoimmune and chronic inflammatory diseases, such as inflammatory bowel diseases (IBD). Although rapid progress was made elucidating induction and functional heterogeneity of Th17 responses, the underlying molecular effects of Th17 response including the most relevant different cell targets of Th17 cytokines remain poorly understood. Cytokines produced by Th17 cells have broad effects on both hematopoietic and nonhematopoietic cells and can act in synergy with various inflammatory factors. In this review, we will focus on the effects of Th17-derived cytokines in the gastrointestinal tract and discuss how Th17 responses can affect both innate and adaptive immunity and may contribute to the pathogenesis of inflammatory GI processes.

IL-17A and Th17 cells in lung inflammation: an update on the role of Th17 cell differentiation and IL-17R signaling in host defense against infection

The significance of Th17 cells and interleukin- (IL-)17A signaling in host defense and disease development has been demonstrated in various infection and autoimmune models. Numerous studies have indicated that Th17 cells and its signature cytokine IL-17A are critical to the airway's immune response against various bacteria and fungal infection. Cytokines such as IL-23, which are involved in Th17 differentiation, play a critical role in controlling Klebsiella pneumonia (K. pneumonia) infection. IL-17A acts on nonimmune cells in infected tissues to strengthen innate immunity by inducing the expression of antimicrobial proteins, cytokines, and chemokines. Mice deficient in IL-17 receptor (IL-17R) expression are susceptible to infection by various pathogens. In this review, we summarize the recent advances in unraveling the mechanism behind Th17 cell differentiation, IL-17A/IL-17R signaling, and also the importance of IL-17A in pulmonary infection.

Expression of interleukin-22/STAT3 signaling pathway in ulcerative colitis and related carcinogenesis

AIM

To investigate the expression of interleukin (IL)-22 and its related proteins in biopsy specimens from patients with ulcerative colitis (UC) and UC-related carcinogenesis.

METHODS

Biopsy specimens were obtained from patients with inactive (n = 10), mild-to-moderately active (n = 30), severely active (n = 34), initial (n = 30), and chronic UC (n = 44), as well as UC patients with dysplasia (n = 10). Specimens from patients without colonic abnormalities (n = 20) served as controls. Chronic colitis in experimental mice was induced by 2.5% dextran sodium sulfate. The expression levels of IL-22, IL-23, IL-22R1 and phosphorylated STAT3 (p-STAT3) were determined by immunohistochemistry. Bcl-2, cyclin D1 and survivin expression was detected by Western blotting.

RESULTS

Patients with active UC had significantly more IL-22, IL-23, IL-22R1 and p-STAT3-positive cells than the patients with inactive UC and normal controls. Furthermore, IL-22 and related proteins were closely related to the severity of the colitis. The expression of IL-22 and IL-22R1 in the tissue of initial UC was stronger than in that of chronic UC, whereas the expression of p-STAT3 was significantly increased in chronic UC tissues. In dysplasia tissues, the expression level of IL-22 and related proteins was higher compared with controls. Mouse colitis model showed that expression of IL-22, IL-22R1 and IL-23 was increased with time, p-STAT3 and the downstream gene were also remarkably upregulated.

CONCLUSION

IL-22/STAT3 signaling pathway may be related to UC and UC-induced carcinogenesis and IL-22 can be used as a biomarker in judging the severity of UC.

Depletion of IL-22 during culture enhanced antigen-driven IFN-γ production by CD4(+)T cells from patients with active TB

In this study, we mainly investigated the expression of IFN-γ and IL-22-producing CD4(+)T cells, the relationship between the two cytokines in human tuberculosis. We showed that IFN-γ and IL-22 were induced by human mycobacterial infection. Besides, CD4(+)T cells expressing IFN-γ and IL-22 were significantly elevated following PPD stimulation. In addition, IFN-γ and IL-22 -expressing CD4(+)T cells were distinct from each other. We also found that there was a reciprocal relationship between IFN-γ and IL-22 production. The production of IL-22 was markedly enhanced in the absence of IFN-γ, also, the expression of IFN-γ was increased when the IL-22 signaling was inhibited by monoclonal anti-IL-22 mAb. Furthermore, data revealed that the detectable IL-22 affected the phynotype of IFN-γ(+)CD4(+)T cells. IL-22 induced up-regulation of CD27 expression in IFN-γ(+)CD4(+)T cells, which might further confirm that IL-22 had an effect on the response of IFN-γ. Thus, this work provides a previous unknown relationship between IFN-γ and IL-22 in human TB disease.

Clinical significance of circulating interleukin-23 as a prognostic factor in breast cancer patients

Little is known about specific IL-23 alterations associated with breast cancer and the data available are still controversial. Therefore, the evaluation of changes in serum IL-23 levels may add further information on the role of this cytokine in breast cancer patients. The aim of this study was to evaluate prospectively the prognostic importance of circulating IL-23 in patients with untreated breast cancer, respect to healthy controls, and the association with clinico-pathological variables. The study involved 50 women diagnosed with stages I-IV breast cancer and 38 healthy controls. Of the 50 breast cancer patients, 37 women were recruited prior to their initial adjuvant chemotherapy and 13 prior to receive first line chemotherapy for metastatic disease. Adjuvant chemotherapy patients were at least in their 4th week post-surgery. IL-23 serum concentrations were measured by a quantitative enzyme immunoassay technique. We found a statistically significant higher systemic cytokine value in women with cancer in comparison with the control group (14.52±11.39 pg/ml vs. 6.35±4.63 pg/ml, P<0.0001). Patients with shorter overall survival presented higher IL-23 values, suggesting a negative prognostic correlation. There was no significant differences in IL-23 levels among patients according to the biomolecular characteristics, the different subtypes and the presence of metastatic disease. This work investigated, for the first time, the role of IL-23 in breast cancer patients showing a significant increase respect the control group. However, further validations are needed in larger studies to better investigate the implications of IL-23 increase in these patients.

Pituitary adenylate cyclase-activating peptide and vasoactive intestinal polypeptide bias Langerhans cell Ag presentation toward Th17 cells

Epidermal Langerhans cells (LCs) are dendritic APCs that play an important role in cutaneous immune responses. LCs are associated with epidermal nerves and the neuropeptides vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) inhibit LC Ag presentation for Th1-type immune responses. Here, we examined whether PACAP or VIP modulates LC Ag presentation for induction of IL-17A-producing CD4(+) T cells. Treatment with VIP or PACAP prior to in vitro LC Ag presentation to CD4(+) T cells enhanced IL-17A, IL-6, and IL-4 production, decreased interferon (IFN)-γ and interleukin (IL)-22 release, and increased RORγt and Gata3 mRNA expression while decreasing T-bet expression. The CD4(+) T-cell population was increased in IL-17A- and IL-4-expressing cells and decreased in IFN-γ-expressing cells. Addition of anti-IL-6 mAb blocked the enhanced IL-17A production seen with LC preexposure to VIP or PACAP. Intradermal administration of VIP or PACAP prior to application of a contact sensitizer at the injection site, followed by harvesting of draining lymph node CD4(+) T cells and stimulation with anti-CD3/anti-CD28 mAbs, enhanced IL-17A and IL-4 production but reduced production of IL-22 and IFN-γ. PACAP and VIP are endogenous mediators that likely regulate immunity and immune-mediated diseases within the skin.

The immunopathophysiology of multiple sclerosis

This review explores the principle features of the immunopathology of multiple sclerosis (MS), particularly relapsing-remitting MS. It highlights the emerging concepts in the pathogenesis of MS in the context of known features of pathology, including the characterization of cytokine networks promoting inflammatory damage of the central nervous system, B-cell involvement, and inflammatory damage of axons and neurons. This article preferentially focuses on MS rather than animal models of the disease, such as experimental autoimmune encephalomyelitis.

STAT3-dependent effects of IL-22 in human keratinocytes are counterregulated by sirtuin 1 through a direct inhibition of STAT3 acetylation

IL-22 has a pathogenetic role in psoriasis, where it is responsible for the altered proliferation and differentiation of keratinocytes and induces inflammatory molecules. The IL-22-induced effects are mediated by STAT3, whose activity is proportional to acetylation in lysine (Lys)685 and phosphorylation in tyrosine (Tyr)705. Lys 685 acetylation of STAT3 is inhibited by sirtuin (SIRT)1, a class III deacetylase promoting keratinocyte differentiation. Due to the opposite effects of IL-22 and SIRT1, we investigated whether IL-22-induced effects in keratinocytes could be regulated by SIRT1 through control of STAT3. We found that SIRT1 opposes the IL-22-induced STAT3 activity by deacetylating STAT3 and reducing STAT3 Tyr705 phosphorylation. By controlling STAT3, SIRT1 also influences the IL-22-induced expression of molecules involved in proliferation and inflammation as well as proliferation and migration processes in cultured keratinocytes. Although SIRT1 levels were similar in keratinocytes of healthy individuals and patients with psoriasis, they were reduced in psoriatic skin lesions, with the lymphokine IFN-γ inhibiting SIRT1 expression. Concomitantly, IFN-γ enhanced basal acetylation of STAT3 and its phosphorylation induced by IL-22. In conclusion, STAT3-dependent IL-22 signaling and effects in keratinocytes are negatively regulated by SIRT1. In skin affected by psoriasis, SIRT1 is down-regulated by IFN-γ, which thus renders psoriatic keratinocytes more prone to respond to IL-22.

Increased activity of Th-17 and Th-9 lymphocytes and a skewing of the post-thymic differentiation pathway are seen in Alzheimer's disease

Inflammatory mediators are responsible for the neuroinflammation observed in Alzheimer's disease (AD), a phenomenon that might be the culprit of disease or, possibly, a reaction to pathology. To better investigate inflammation in AD we performed an extensive immunophenotypic and functional analysis of amyloid-beta (Aβ) stimulated T lymphocytes in patients with a diagnosis of AD comparing data to those obtained in individuals with mild cognitive impairment (MCI) or aged-matched healthy individuals (HC). Results showed that IL-21- and IL-9-producing Aβ stimulated CD4(+) T cells, as well as IL-23- and IL-6-producing monocytes and CD4(+) T cells expressing the RORγ and NFATc1 transcriptional factors (TF), were significantly increased, whereas IL-10-producing monocytes were decreased in AD. Notably, GATA-3 TF-expressing CD4(+) T lymphocytes were significantly increased in MCI alone. Analysis of the post-thymic differentiation pathway indicated that Aβ specific naïve and central memory CD4(+) T lymphocytes were diminished whereas effector memory and terminally differentiated CD4(+) T lymphocytes were increased in AD and MCI compared to HC. Data herein indicate that cytokines (IL-21, IL-6, IL-23) and TF (RORγ) involved in the differentiation of Th-17 cells), as well as cytokines (IL-21, IL-22) generated by such cells, and IL-9, produced by Th-9 cells, are significantly increased in AD. This is accompanied by a shift of post-thymic differentiation pathways favoring the accumulation of differentiated, effector T lymphocytes. These data shed light on the nature of AD-associated neuroinflammation. A better understanding of the complexity of this phenomenon could facilitate the search for novel therapeutic strategies.

Spontaneous secretion of interleukin-17 and -22 by human cervical cells in Chlamydia trachomatis infection

To investigate whether IL-17A (IL-17) and IL-22 are produced in response to Chlamydia trachomatis infection, the cervical washes of 27 women with C. trachomatis infection and 17 C. trachomatis negative controls were collected. The levels of cytokines were determined in the cervical wash and in the supernatant of cervical and systemic cell cultures upon C. trachomatis antigen stimulation. C. trachomatis infection appeared to activate local IL-17 and IL-22 production more efficiently than IFN-γ production. In the cervical wash of infected women, median concentrations of IL-17 and -22 were 5- and 3-fold higher, respectively, than in negative controls. The spontaneous intracellular expression of these cytokines was analysed by flow cytometry in blood and cervical cells and 26% of cervical mononuclear cells from infected women were shown to produce IL-22 and 12% to coproduce IL-17 and IL-22. In addition, it was demonstrated that 20-25% of IL-22 producing and IL-17-IL-22 coproducing cervical CD4+ T cells expressed the mucosal homing receptor CCR6. These results suggest that CCR6 is involved in the migration of these cells to the cervix and that IL-17 and IL-22 might play a role in the immune response at the site of C. trachomatis infection.

Cutting edge: crucial role of IL-1 and IL-23 in the innate IL-17 response of peripheral lymph node NK1.1- invariant NKT cells to bacteria

We have shown previously that peripheral lymph node-resident retinoic acid receptor-related orphan receptor γt(+) NK1.1(-) invariant NKT (iNKT) cells produce IL-17A independently of IL-6. In this study, we show that the concomitant presence of IL-1 and IL-23 is crucial to induce a rapid and sustained IL-17A/F and IL-22 response by these cells that requires TCR-CD1d interaction and partly relies on IL-23-mediated upregulation of IL-23R and IL-1R1 expression. We further show that IL-1 and IL-23 produced by pathogen-associated molecular pattern-stimulated dendritic cells induce this response from NK1.1(-) iNKT cells in vitro, involving mainly TLR2/4-signaling pathways. Finally, we found that IL-17A production by these cells occurs very early and transiently in vivo in response to heat-killed bacteria. Overall, our study indicates that peripheral lymph node NK1.1(-) iNKT cells could be a source of innate Th17-related cytokines during bacterial infections and supports the hypothesis that they are able to provide an efficient first line of defense against bacterial invasion.

Staphylococcal exotoxins are strong inducers of IL-22: A potential role in atopic dermatitis

BACKGROUND

Patients with atopic dermatitis (AD) and psoriasis are frequently colonized with Staphylococcus aureus that produces staphylococcal enterotoxin B (SEB) and α-toxin. In patients with AD, S aureus colonization is positively correlated with the severity of their eczema. Moreover, IL-22-producing cells have been shown to accumulate in AD skin and to correlate with disease severity.

OBJECTIVE

To assess IL-22 production in response to SEB and sublytic α-toxin stimulation in patients with AD and psoriasis compared with healthy controls.

METHODS

IL-22 induction was investigated in PBMCs, T cells, and autologous cocultures of keratinocytes and T cells on SEB and α-toxin stimulation in a time-dependent and dose-dependent manner at the mRNA and protein (ELISA and flow cytometry) level. Anti-IL-1 receptor or anti-IL-6 antibodies were used in blocking experiments.

RESULTS

Staphylococcal enterotoxin B and sublytic α-toxin concentrations induced IL-22 production in PBMCs and isolated CD4(+) T cells. IL-22 secretion was enhanced by α-toxin stimulation in autologous cocultures of keratinocytes and T cells. In T cells and PBMCs from patients with AD, IL-22 secretion was significantly enhanced on α-toxin stimulation compared with patients with psoriasis and healthy controls.

CONCLUSION

Increased IL-22 secretion induced by staphylococcal exotoxins in the skin partially explains how skin colonization and infection with S aureus can contribute to chronic skin inflammation in AD.

Interleukin-22: a cytokine produced by T, NK and NKT cell subsets, with importance in the innate immune defense and tissue protection

Interleukin (IL)-22 is a member of the IL-10 cytokine family that is produced by special immune cell populations, including Th22, Th1, and Th17 cells, classical and non-classical (NK-22) NK cells, NKT cells, and lymphoid tissue inducer cells. This cytokine does not influence cells of the hematopoietic lineage. Instead, its target cells are certain tissue cells from the skin, liver and kidney, and from organs of the respiratory and gastrointestinal systems. The main biological role of IL-22 includes the increase of innate immunity, protection from damage, and enhancement of regeneration. IL-22 can play either a protective or a pathogenic role in chronic inflammatory diseases depending on the nature of the affected tissue and the local cytokine milieu. This review highlights the primary effects of IL-22 on its target cells, its role in the defense against infections, in tumorigenesis, in inflammatory diseases and allergy as well as the potential of the therapeutic modulation of IL-22 action.

Phosphatidylinositol 3 kinase modulation of trophoblast cell differentiation

BACKGROUND

The trophoblast lineage arises as the first differentiation event during embryogenesis. Trophoblast giant cells are one of several end-stage products of trophoblast cell differentiation in rodents. These cells are located at the maternal-fetal interface and are capable of invasive and endocrine functions, which are necessary for successful pregnancy. Rcho-1 trophoblast stem cells can be effectively used as a model for investigating trophoblast cell differentiation. In this report, we evaluated the role of the phosphatidylinositol 3-kinase (PI3K) signaling pathway in the regulation of trophoblast cell differentiation. Transcript profiles from trophoblast stem cells, differentiated trophoblast cells, and differentiated trophoblast cells following disruption of PI3K signaling were generated and characterized.

RESULTS

Prominent changes in gene expression accompanied the differentiation of trophoblast stem cells. PI3K modulated the expression of a subset of trophoblast cell differentiation-dependent genes. Among the PI3K-responsive genes were those encoding proteins contributing to the invasive and endocrine phenotypes of trophoblast giant cells.

CONCLUSIONS

Genes have been identified with differential expression patterns associated with trophoblast stem cells and trophoblast cell differentiation; a subset of these genes are regulated by PI3K signaling, including those impacting the differentiated trophoblast giant cell phenotype.

Increased expression of cardiac IL-17 after burn

Background

Cardiac dysfunction is a common complication associated with major burns. While recent findings have linked the Th-17 T-cell response to the development of autoimmune myocarditis, the role of IL-17 and the Th-17 T-cell response in the development of post-burn cardiac dysfunction remains unknown.

Methods

Male C57BL/6 mice were subjected to a major burn (3^rd degree, 25% TBSA) or sham treatment. Three hours after injury plasma and tissue (i.e., heart, lung, liver, small intestine) samples were collected and analyzed for the expression of Th-17 cytokine (i.e., IL-6, IL-17, IL-22, IL-23, TGF-β) levels by ELISA.

Results

Cardiac tissue levels of the Th-17 cytokines, IL-6, IL-17 and IL-22 were significantly elevated at 3 hrs after burn as compared to sham levels. IL-17 was analyzed 1, 3 and 7 days after burn and showed a return to baseline levels and without a difference in the burn group. Burn-induced alterations in the level of these cytokines in plasma or other tissues were not evident. The cardiac Th-17 cytokine response after burn injury was specific, as cardiac levels of Th-1 (IFN-γ) and Th-2 (IL-10) cytokines were not significantly affected after injury. The cardiac Th-17 response correlated with a significant increase in Troponin levels at 3 hr. after burn.

Conclusion

These findings indicate that early after burn, cardiac tissue is associated with significantly elevated levels of Th-17 cytokines. The early Th-17 response after burn appears to be specific for cardiac tissue and may promote myocardial inflammation and dysfunction associated with this form of trauma.

IL-22 defines a novel immune pathway of antifungal resistance

The role of IL-17 and Th17 cells in immunity vs. pathology associated with the human commensal Candida albicans remains controversial. Both positive and negative effects on immune resistance have been attributed to IL-17/Th17 in experimental candidiasis. In this study, we provide evidence that IL-22, which is also produced by Th17 cells, has a critical, first-line defense in candidiasis by controlling the growth of infecting yeasts as well as by contributing to the host's epithelial integrity in the absence of acquired Th1-type immunity. The two pathways are reciprocally regulated, and IL-22 is upregulated under Th1 deficiency conditions and vice versa. Whereas both IL-17A and F are dispensable for antifungal resistance, IL-22 mediates protection in IL-17RA-deficient mice, in which IL-17A contributes to disease susceptibility. Thus, our findings suggest that protective immunity to candidiasis is made up of a staged response involving an early, IL-22-dominated response followed by Th1/Treg reactivity that will prevent fungal dissemination and supply memory.

Human Langerhans cells induce distinct IL-22-producing CD4+ T cells lacking IL-17 production

IL-22 is a cytokine that acts mainly on epithelial cells. In the skin, it mediates keratinocyte proliferation and epidermal hyperplasia and is thought to play a central role in inflammatory diseases with marked epidermal acanthosis, such as psoriasis. Although IL-22 was initially considered a Th17 cytokine, increasing evidence suggests that T helper cells can produce IL-22 even without IL-17 expression. In addition, we have shown the existence of this unique IL-22-producing T cell in normal skin and in the skin of psoriasis and atopic dermatitis patients. In the present study, we investigated the ability of cutaneous resident dendritic cells (DCs) to differentiate IL-22-producing cells. Using FACS, we isolated Langerhans cells (LCs; HLA-DR(+)CD207(+) cells) and dermal DCs (HLA-DR(hi)CD11c(+)BDCA-1(+) cells) from normal human epidermis and dermis, respectively. Both LCs and dermal DCs significantly induced IL-22-producing CD4(+) and CD8(+) T cells from peripheral blood T cells and naive CD4(+) T cells in mixed leukocyte reactions. LCs were more powerful in the induction of IL-22-producing cells than dermal DCs. Moreover, in vitro-generated LC-type DCs induced IL-22-producing cells more efficiently than monocyte-derived DCs. The induced IL-22 production was more correlated with IFN-gamma than IL-17. Surprisingly, the majority of IL-22-producing cells induced by LCs and dermal DCs lacked the expression of IL-17, IFN-gamma, and IL-4. Thus, LCs and dermal DCs preferentially induced helper T cells to produce only IL-22, possibly "Th22" cells. Our data indicate that cutaneous DCs, especially LCs, may control the generation of distinct IL-22 producing Th22 cells infiltrating into the skin.

Dendritic and tumor cell fusions transduced with adenovirus encoding CD40L eradicate B-cell lymphoma and induce a Th17-type response

Fusion of dendritic cells and tumor cells (FCs) constitutes a promising tool for generating an antitumor response because of their capacity to present tumor antigens and provide appropriate costimulatory signals. CD40-CD40L interaction has an important role in the maturation and survival of dendritic cells and provides critical help for T-cell priming. In this study, we sought to improve the effectiveness of FC vaccines in a murine model of B-cell lymphoma by engineering FCs to express CD40L by means of an adenovirus encoding CD40L (Adv-CD40L). Before transduction with Adv-CD40L, no CD40L expression was detected in FCs, DCs or tumor cells. The surface expression of CD40L in FC transduced with Adv-CD40L (FC-CD40L) ranged between 50 and 60%. FC-CD40L showed an enhanced expression of CD80, CD86, CD54 and MHC class II molecules and elicited a strong in vitro immune response in a syngeneic mixed lymphocyte reaction. Furthermore, FC-CD40L showed enhanced migration to secondary lymphoid organs. Splenocytes from mice treated with FC-CD40L had a dramatic increase in the production of IL-17, IL-6 and IFN-gamma, compared with controls. Treatment with the FC-CD40L vaccine induced regression of established tumors and increased survival. Our data demonstrate that FC transduced with Adv-CD40L enhances the antitumor effect of FC vaccines in a murine lymphoma model and this is associated with an increased Th17-type immune response.

IL-21 and T follicular helper cells

Upon encounter with antigen, CD4(+) T cells differentiate into effector T(h) subsets with distinctive functions that are related to their unique cytokine profiles and anatomical locations. One of the most important T(h) functions is to provide signals to developing B cells that induce specific and appropriate antibody responses. The major CD4(+) T cell subset that helps B cells is the T follicular helper (T(FH)) cell, whose expression of the chemokine receptor CXCR5 [chemokine (C-X-C motif) receptor 5] serves to localize this cell to developing germinal centers (GCs) where it provides instructive signals leading to Ig class switching and somatic mutation. T(FH) cells produce high levels of IL-21, a cytokine that is critical for GC formation and also for the generation of T(FH) cells. Although T(FH) cells have been found to produce cytokines characteristic of other T(h) subsets, they represent a distinct lineage whose development is driven by the transcription factor B-cell CLL lymphoma-6 (BCL6). Consistent with their critical role in the generation of antibody responses, dysregulated T(FH) function has been associated with the development of systemic autoimmunity. Here, we review the role of IL-21 in the regulation of normal T(FH) development and function as well as in progression of autoimmune responses.

Encephalitogenic T cells that stably express both T-bet and ROR gamma t consistently produce IFNgamma but have a spectrum of IL-17 profiles

Th1/Th17 cells, secreting both IFNgamma and IL-17, are often associated with inflammatory pathology. We cloned and studied the cytokine phenotypes of MBP-specific, TCR-identical encephalitogenic CD4+ cells in relationship to Th1- and Th17-associated transcription factors T-bet and RORgammat. IFNgamma-producing cells could be sub-divided into those that are T-bet(+)/RORgammat(-) and those that are T-bet(+)/RORgammat(+). The latter comprises a spectrum of phenotypes, as defined by IL-17 production, and can be induced to up-regulate IL-23R with IL-12 or IL-23. The former, bona fide Th1 cells, lack IL-23R expression under all conditions. In vivo, T-bet(+)/RORgammat(-) and T-bet(+)/RORgammat(+) clones induce EAE equally well.