CD4 T Cells but Not Th17 Cells Are Required for Mouse Lung Transplant Obliterative Bronchiolitis

Nitric oxide (NO) is a ubiquitous mediator of inflammation and immunity, involved in the pathogenesis and control of infectious diseases, autoimmunity, and cancer. We observed that the expression of nitric oxide synthase-2 (NOS2/iNOS) positively correlates with Th17 responses in patients with ovarian cancer (OvCa). Although high concentrations of exogenous NO indiscriminately suppress the proliferation and differentiation of Th1, Th2, and Th17 cells, the physiological NO concentrations produced by patients’ myeloid-derived suppressor cells (MDSCs) support the development of RORγt(Rorc)+IL-23R+IL-17+ Th17 cells. Moreover, the development of Th17 cells from naive-, memory-, or tumor-infiltrating CD4+ T cells, driven by IL-1β/IL-6/IL-23/NO-producing MDSCs or by recombinant cytokines (IL-1β/IL-6/IL-23), is associated with the induction of endogenous NOS2 and NO production, and critically depends on NOS2 activity and the canonical cyclic guanosine monophosphate (cGMP)–cGMP-dependent protein kinase (cGK) pathway of NO signaling within CD4+ T cells. Inhibition of NOS2 or cGMP–cGK signaling abolishes the de novo induction of Th17 cells and selectively suppresses IL-17 production by established Th17 cells isolated from OvCa patients. Our data indicate that, apart from its previously recognized role as an effector mediator of Th17-associated inflammation, NO is also critically required for the induction and stability of human Th17 responses, providing new targets to manipulate Th17 responses in cancer, autoimmunity, and inflammatory diseases.

Download Full-text

Homeostatic Proliferation of Naive CD4+ T Cells in Mesenteric Lymph Nodes Generates Gut-Tropic Th17 Cells

The Journal of Immunology ◽

10.4049/jimmunol.1203111 ◽

2013 ◽

Vol 190 (11) ◽

pp. 5788-5798 ◽

Cited By ~ 26

Author(s):

Takeshi Kawabe ◽

Shu-lan Sun ◽

Tsuyoshi Fujita ◽

Satoshi Yamaki ◽

Atsuko Asao ◽

...

Keyword(s):

T Cells ◽

Lymph Nodes ◽

Cd4 T Cells ◽

Th17 Cells ◽

Homeostatic Proliferation ◽

Mesenteric Lymph Nodes ◽

Mesenteric Lymph

Download Full-text

Malignant B Cells Skew the Balance between Treg Cell and TH17 Cell Differentiation in B-Cell Non-Hodgkin Lymphoma (NHL).

Blood ◽

10.1182/blood.v110.11.1347.1347 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1347-1347

Author(s):

Zhi-Zhang Yang ◽

Anne J. Novak ◽

Thomas E. Witzig ◽

Stephen M. Ansell

Keyword(s):

T Cells ◽

Cell Differentiation ◽

B Cells ◽

B Cell ◽

Cd4 T Cells ◽

Th17 Cell ◽

Th17 Cells ◽

Foxp3 Expression ◽

Treg Cells ◽

Th17 Cell Differentiation

Abstract Numerous clinical therapies have attempted to modulate tumor cell immunity, but for the most part, have proven unsuccessful. The inability to produce or augment an effective immune response is due in part to regulatory T (Treg) cells, which inhibit CD4 and CD8 T cell function. Our group has recently shown that Treg cell numbers are elevated in NHL tumors and that NHL B cells induce the development of Treg cells thereby inhibiting anti-tumor responses. The ability of NHL B cells to direct the cellular composition of their microenvironment is critical to our understanding of tumor immunity and we therefore wanted to determine if NHL B cells also directed the expansion or reduction of other T cell populations. IL-17-secreting CD4+ T cells (TH17), a newly characterized CD4+ T helper cell lineage, promote inflammation and play an important role in autoimmune disease. IL-17 has been shown to inhibit tumor cell growth suggesting a potential role for TH17 cells in anti-tumor immunity. We therefore set out to determine if TH17 cells were present in NHL tumors and whether or not their numbers were regulated by NHL B cells. Using unsorted mononuclear cells from malignant lymph nodes, we were unable to detect IL-17 expression in resting CD4+ T cells or CD4+ T cells activated with PMA/Ionomycin stimulation (less than 1%). However, IL-17-secreting CD4+ T cells could be detected in significant numbers in inflammatory tonsil and normal PBMCs. Interestingly, depletion of CD19+ NHL B cells from mononuclear cells obtained from patient biopsies resulted in detection of a clear population of IL-17-secreting CD4+ T cells (5%). These results suggest that NHL B cells suppress TH17 cell differentiation. The frequency of IL-17-secreting CD4+ T cells could not be further enhanced by the addition of exogenous TGF-b and IL-6, a cytokine combination favoring for TH17 differentiation, suggesting a further impairment of TH17 cell differentiation in the tumor microenvironment. In contrast, Foxp3 expression could be detected in resting CD4+ T cells (30%) and could be induced in CD4+CD25−Foxp3− T cells activated with TCR stimulation (28%). Contrary to the inhibition of TGF-b-mediated TH17 differentiation, Foxp3 expression could be dramatically upregulated by TGF-b in intratumoral CD4+ T cells (35%). In addition, lymphoma B cells strongly enhanced Foxp3 expression in intratumoral CD4+CD25−Foxp3−. Furthermore, when added together, the frequency of Foxp3+ T cells and Foxp3-inducible cells reached up to 60% of CD4+ T cells in tumor microenvironment of B-cell NHL. These findings suggest that the balance of effector TH17 cells and inhibitory Treg cells is disrupted in B-cell NHL and significantly favors the development of inhibitory Treg cells. Our data indicate that lymphoma B cells are key factor in regulating differentiation of intratumoral CD4+ T cells toward inhibitory CD4+ T cells.

Download Full-text

Overexpansion of Th17 and Th1/17 Cells in Patients with Myelodysplastic Syndrome

Blood ◽

10.1182/blood.v112.11.2698.2698 ◽

2008 ◽

Vol 112 (11) ◽

pp. 2698-2698

Author(s):

Elena E. Solomou ◽

A. Tsanaktsi ◽

V. Fertakis ◽

K. Dallas ◽

S. Karambina ◽

...

Keyword(s):

T Cells ◽

Transcription Factor ◽

Cd4 T Cells ◽

Th17 Cells ◽

Mononuclear Cells ◽

Mapk Pathway ◽

Immunosuppressive Treatment ◽

Healthy Controls ◽

Orphan Nuclear Receptor

Abstract IL17-producing T cells have been recently described as a distinct T cell helper population (Th17 cells) characterized by expression of membrane CD4 and IL23R and intracellular expression of the orphan nuclear receptor RORgt. In Th17 cells the transcription factor RORgt induces the transcription of IL17 gene, whereas in Th1 cells the transcription factor Tbet is responsible for the transcription of IFNg gene. Th1 along with Th17 cells are thought to contribute to the pathogenesis of autoimmune diseases. In murine models Th17 cells are fully polarized. In humans a proportion of Th17 cells are also positive for interferon gamma (IFN-g); they are named Th1/17 cells and their function is yet unclear. In patients with colitis and seronegative arthritis Th17 cells are increased. The induction of Th17 and Th1/17 in patients with MDS has not been previously evaluated. To examine the expression of Th17 and Th1/17 cells in this disease, peripheral blood mononuclear cells (PBMC) from patients with MDS were cultured in vitro for 6 days in RPMI-1640, 15% FBS supplemented with PHA (0.1 μg/mL) and IL-2 (10 ng/mL). Percentages of CD4+IL23R+IL-17+ T cells (Th17) and CD4+IL23R+IL17+IFN-g+ T cells (Th1/17) in patients with MDS were determined by flow cytometry: Th17 cells were markedly increased in patients (n=30) compared to healthy controls (n=15), (17.5% ± 3.4 vs 2.5% ± 0.4, p=0.008). Th1/Th17 cells were also significantly increased in MDS patients compared to controls (15.17% ± 2.80 vs 2.56% ± 0.80, p=0.008). None of the patients had been on immunosuppressive treatment or transfused before sampling. In multi-transfused patients with no underlying hematologic disease examined (n=3) the Th17 and Th1/17 populations were comparable to those of healthy donors. In patients with MDS the majority of the Th17 cells expressed also IFNg (90.07% ± 2.87) whereas in healthy controls only 59.7% ± 5.5 of the Th17 cells were also positive for IFNg (p<0.0001). There were no differences between different subtypes of MDS (RA, RARS, and RAEB). Using confocal microscopy, purified CD4+ T cells from PBMC cultures from patients (n=5) showed increased Tbet and RORgt expression at the single-cell level compared to controls (n=3),(T-bet: 22.03 ± 1.20 vs 11.60 ± 0.35 arbitrary units respectively, p<0.0001 and RORãt: 28.90 ± 0.35 vs 21.03 ± 1.20 arbitrary units, p=0.0008. For each sample 100 cells were analyzed). We next asked whether kinases involved in the induction of Tbet are also involved in the induction of RORgt. We analyzed the effects of rottlerin, a PKC-theta inhibitor, SB203580, a p38 MAPK pathway inhibitor, and PD98059, an ERK pathway inhibitor, on Th17 and Th1/17 cell induction in patients (n=7) and controls (n=4). Rottlerin decreased the Th17 content in patients and controls by 45.0%, and the Th1/17 content by 64.8%. SB203580 showed a 17% and 18% decrease on Th17 and on Th1/17 content, respectively, in patients and controls. PD98059 showed no effect on Th17 and Th1/17 populations in patients and controls. By immunoblots, in normal CD4+T cells rottlerin decreased both T-bet and RORgt protein levels by 50% and 20%, respectively. SB203580, decreased RORgt levels by 25%, and PD98059 did not obviously decrease Tbet but decreased RORgt levels by 20%. CD4+IL23R+IL-17+ T cells and CD4+IL23R+IL17+IFN-g+ T cells are increased in most patients with MDS. T cells have recently been implicated in MDS pathogenesis. Although more studies are needed in order to define the role of Th17 and Th1/17 cells in the pathogenesis of MDS, our in vitro data with the kinase inhibitors may suggest a probable therapeutic target for patients with MDS.

Download Full-text

IL-17A-Expressing CD4+ T Cells Must Acquire the Expression of T-Bet and IFN-γto Destroy Tumor Cells In Vivo.

Blood ◽

10.1182/blood.v114.22.468.468 ◽

2009 ◽

Vol 114 (22) ◽

pp. 468-468

Author(s):

Pawel Muranski ◽

Sid P Kerkar ◽

Zachary A Borman ◽

Robert Reger ◽

Luis Sanchez-Perez ◽

...

Keyword(s):

T Cells ◽

Treatment Efficacy ◽

Cd4 T Cells ◽

Th17 Cells ◽

End Effector ◽

Polarized Cells ◽

Ifn Γ

Abstract Abstract 468 We have recently demonstrated that Th17-polarized TCR transgenic CD4+ T cells specific for TRP-1 melanoma antigen are superior to Th1-polarized cells in mediating effective anti-tumor responses against advanced disease after adoptive transfer. The therapeutic activity of Th17-skewed cells is critically dependent on their ability to secrete IFN-γ, suggesting that the Th17 subset might evolve in vivo. However, the developmental program of Th17-polarized cells in vivo remains substantially un- elucidated. We developed a novel TCR-transduction technique that enabled us to rapidly confer specificity for a cognate antigen upon any population of T cells, regardless of its genetic background, its previous polarization history or its state of differentiation. Using adoptive transfers into tumor-bearing hosts, we were able to study the functionality of these genetically-engineered T cells in vivo. In vitro, CD4+ T cells cultured in type 17 conditions acquired end-effector phenotype (CD62Llow, CD45RBlow), but proliferated slower than cells grown in type 1 condition. Thus, we hypothesized that Th17-polarized cells might represent a less mature, more central-memory like subset. This notion was supported by their ability to secrete high quantities of IL-2 and higher expression of IL-7 receptor. In contrast, Th1-polarized cells upon in vitro re-stimulation upregulated PRDM1 that encodes BLIMP1, a molecule associated with the end-effector senescent phenotype. Moreover, Th1-skewed cells overexpressed caspase 3 and were prone to activation-induced cell death as measured by annexin V assay, while type 17 cells were resistant to apoptosis, and robustly expanded in secondary cultures. Using the TCR gene transfer technique we tested the treatment outcomes when Th17-polarized cells deficient for IL-17A were used. In contrast to wild-type (WT)-derived Th17 cells that effectively eradicated established tumors, we observed significant impairment of treatment with IL-17A-deficent cells. Similarly, we observed reduction in treatment efficacy when CCR6-deficient Th17 cells were transferred. CCR6 is a receptor for CCL20, a chemokine highly induced Th17 cells and thought to contribute to the trafficking of those cells to the site of inflammation. In both cases however, the addition of exogenous vaccination and IL-2 significantly improved treatment efficacy. Thus, we concluded that Th17-associated factors play the role in the anti-cancer activity of type 17 cells. To address the question whether plasticity of Th17-skewed effectors is important for their function upon ACT, we treated animals with TCR-transduced Th17-skewed cells derived from IFN-γ-deficient CD4+ cells as well as from t-bet-deficient mice, which are not able to develop type 1 responses. In contrast to WT-derived Th17 effectors, IFN-γ-deficient cells did not show any anti-tumor activity, while t-bet-deficient Th17 cells were able to mediate only minimal delay in tumor growth, suggesting that indeed the capacity to acquire Th1-like properties is essential for the anti-tumor function of Th17-skewed lymphocytes. Overall, here we demonstrate that TCR gene engineered Th17-polarized cells can efficiently treat advanced tumor. The high activity of in vitro-generated anti-tumor Th17 cells relies on the contribution of type 17-associated characteristics, including both the secretion of inflammatory factors IL-17A and CCL20, as well as the superior capacity to survive and expand upon the secondary stimulation. Importantly however, type 1-defining t-bet-mediated plasticity in the lineage commitment is required for the full therapeutic effect, underscoring the dualistic nature of Th17-skewed cells. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Hyperactivable NFAT1 Ameliorates Autoimmune Encephalitis In Vivo.

Blood ◽

10.1182/blood.v114.22.711.711 ◽

2009 ◽

Vol 114 (22) ◽

pp. 711-711

Author(s):

Srimoyee Ghosh ◽

Sergei B Koralov ◽

Irena Stevanovic ◽

Mark S Sundrud ◽

Yoshiteru Sasaki ◽

...

Keyword(s):

T Cells ◽

Transgenic Mice ◽

Cd4 T Cells ◽

Th17 Cells ◽

Autoimmune Encephalitis ◽

Cell Types ◽

Wild Type ◽

Ifn Γ

Abstract Abstract 711 Naïve CD4 T cells differentiate into diverse effector and regulatory subsets to coordinate the adaptive immune response. TH1 and TH2 effector subsets produce IFN-γ and IL-4, respectively, whereas proinflammatory TH17 cells are key regulators of autoimmune inflammation, characteristically produce IL-17 and IL-22 and differentiate in the presence of inflammatory cytokines like IL-6 and IL-21 together with TGF-β. Naive T cells can also differentiate into tissue-protective induced T regulatory (iTreg) cells. NFAT proteins are highly phosphorylated and reside in the cytoplasm of resting cells. Upon dephosphorylation by the Ca2+/calmodulin-dependent serine phosphatase calcineurin, NFAT proteins translocate to the nucleus, where they orchestrate developmental and activation programs in diverse cell types. In this study, we investigated the role of the Ca/NFAT signaling pathway in regulating T cell differentiation and the development of autoimmune diseases. We generated transgenic mice conditionally expressing a hyperactivable version of NFAT1 (AV-NFAT1) from the ROSA26 locus. To restrict AV-NFAT1 expression to the T cell compartment, ROSA26-AV-NFAT1 transgenic mice were bred to CD4-Cre transgenic mice. Naïve CD4 T cells freshly isolated from AV mice produced significantly less IL-2 but increased amounts of the inhibitory cytokine IL-10. To investigate the role of NFAT1 in the generation of TH1, TH2, Tregand TH17 cells, the respective cell types were generated from CD4 T cells of AV mice by in vitro differentiation. T cells from AV-NFAT1 mice exhibited a dysregulation of cytokine expression, producing more IFN-γ and less IL-4. While the numbers of CD4+CD25+ “natural” Treg cells in peripheral lymphoid organs and their in vitro suppressive functions were slightly decreased in AV mice, iTreg generation from CD4+CD25- T cells of AV mice as compared to wild type cells was markedly enhanced. Moreover, TH17 cells generated in vitro from CD4 T cells of AV mice in the presence of IL-6, IL-21 and TGF-β exhibited dramatically increased expression of both IL-10 and IL-17 as compared to wild type controls. To investigate putative NFAT binding sites in the IL-10 and IL-17 gene loci, we performed chromatin immunoprecipitation experiments. We show that NFAT1 can bind at the IL-17 locus at 3 out of 9 CNS regions which are accessible specifically during TH17 but not during TH1 and TH2 differentiation. Furthermore, we provide evidence that NFAT1 binds one CNS region in the IL10-locus in TH17 cells. To verify our observations in vivo, we induced experimental autoimmune encephalitis (EAE) in AV mice and wild type controls with the immunodominant myelin antigen MOG33-55 emulsified in complete Freund‘s adjuvant. While wild type animals showed a normal course of disease with development of tail and hind limb paralysis after approximately 10 days, AV mice showed a markedly weaker disease phenotype with less severe degrees of paralysis and accelerated kinetics of remission. Moreover at the peak of the response, there were fewer CD4+CD25- but more CD4+CD25+ T cells in the CNS of AV animals compared to wild type controls. Surprisingly, these cells produced significantly more IL-2, IL-17 and IFN-γ upon restimulation, even though they displayed decreased disease. In summary, our data provide strong evidence that NFAT1 contributes to the regulation of IL-10 and IL-17 expression in TH17 cells and show that increasing NFAT1 activity can ameliorate autoimmune encephalitis. This could occur in part through upregulation of IL-10 expression as observed in vitro, but is also likely to reflect increased infiltration of regulatory T cells into the CNS as well as increased conversion of conventional T cells into Foxp3+ regulatory T cells within the CNS. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Functional Characterization of CD4+ T-Cells in Aplastic Anemia (AA)

Blood ◽

10.1182/blood.v118.21.1340.1340 ◽

2011 ◽

Vol 118 (21) ◽

pp. 1340-1340 ◽

Cited By ~ 1

Author(s):

Shahram Y Kordasti ◽

Judith C. W. Marsh ◽

Sufyan Al-Khan ◽

Jie Jiang ◽

Alexander E Smith ◽

...

Keyword(s):

T Cells ◽

Treatment Group ◽

High Throughput ◽

Cd4 T Cells ◽

Th17 Cells ◽

Absolute Number ◽

Th2 Cells ◽

Th1 Cells ◽

Ifn Γ ◽

Pre Treatment

Abstract Abstract 1340 We have examined the role of CD4+ T-cells in the pathogenesis of AA in 63 patients, 48 of whom were analyzed at diagnosis and 15 following immunosuppressive therapy (IST). Absolute numbers of CD4+ regulatory T cells (Tregs, defined as CD3+CD4+CD25highCD27+Foxp3+) were lower in pre-treatment AA patients compared to 10 healthy donors (HDs) (5.5 × 106 v 1.4 × 107)(p=0.01). In patients with severe (SAA) and very severe AA (VSAA), the absolute number and frequency of Tregs were lower than non-severe AA (NSAA) (4.4 × 106/L v 1 × 107/L)(p=0.01) and HDs (4.4 × 106/L v 3 × 107/L) (p<0.001). Absolute numbers of Th1 and Th2 cells in all pre-treatment patients were higher compared to HDs (6.4 × 107/L v 1.8 × 107/L)(p=0.03) for Th1 and (2.6 × 107/L v 2.4 × 106/L)(p=0.006) Th2 cells. Although mean percentages of AA Th17 cells were higher than in HDs (1.5% v 0.15%)(p=0.04), differences in absolute numbers were not significant. Absolute numbers of Th2 and Th17 cells were increased in SAA (1.3 × 107/L v 7.4 × 106/L for Th2)(p=0.01) compared to NSAA (5.7 × 106/L v 2.15 × 106/L for Th17)(p=0.02). Ratios of Th1/Tregs (p=0.003), Th2/Tregs (p=0.02), and Th17/Tregs (p=0.001) were higher in SAA and VSAA compared to NSAA. Percentage of both activated (CD4+CD45RA−CD25highFoxp3high) and resting (CD4+CD45RA+ CD25highFoxp3low) Tregs was decreased in AA patients, compared to HDs (p=0.004 and p=0.01), whereas cytokine secreting Tregs (CD4+CD45RA−CD25high Foxp3low) were increased in AA (p<0.003). Sorted Tregs from AA patients did not suppress cytokine secretion by autologous or HD T effectors (Te) cells in 1:1 co-cultures, whereas IL-2 and IFN-γ secretion by AA Te (CD4+CD25lowCD127high) was suppressible by allogeneic Tregs from HDs, confirming Tregs dysfunction. AA Tregs did not inhibit either CD154 or CD69 expression on Te cells. Tregs from AA patients secreted significantly more IFN-γ, TNF-α and IL-17 (p=0.02, p=0.02 and p=0.01, respectively) after 4 hours stimulation with PMA/Ionomycine compared to HDs. Expression levels of FoxP3, ROR□c and T-bet in AA Tregs was normal. IFN-γ secreting cells (Th1) were enriched using enrichment kit then further enriched by FACS sorting. CDR3 region products of TCR Vβ-chain were amplified using Vβ specific forward and Cβ reverse primers. CDR3 PCR products from AA patients and HDs were subjected 454 sequencing (Roche GS FLX titanium). Sequencing was performed to yield an average ‘depth’ in excess of 1000 clonally reads (1000x) for each sample specific CDR3 PCR amp icon. Reads were processed using Roche Amp icon Variant Analyzer software (AVA). Diversity of TCR receptors (measured by spectratyping and confirmed by high throughput deep sequencing) in AA Th1 cells was lower than HDs (p=0.037), as shown by the percentage and number of consensus clusters in total sequence reads. Interestingly, percentages of the most dominant CDR3 clones, revealed by high throughput sequencing, were higher in AA compared to HDs, regardless of spectratyping pattern. Global gene expression of Tregs was compared in 3 pre-IST AA patients and 5 HDs. A unique gene signature consisting of 86 genes that were significant was identified. There were 8 down regulated genes (fold change) in the pre-treatment group; PIN4 (−4.1), OR2T12 (−3.3), AMAC1 (−2.73), PERP (−2.69), UTS2 (−2.27), RNF139 (−2.13), COMMD9 (−2.09) and LOC100128356 (−2.01). The top 10 of 78 up-regulated genes in the pre-treatment group were HBB (19.5), PSME2 (13.8), CSDA (13.07), FAM127A (7.78), EXOSC1 (7.73), BPGM (7.43), CYSLTR1 (7.17), CHPT1 (6.96) and PLAC8 (6.71). qPCR analysis for CSDA, HBB, PSMiE2, PERP, PIN4, and UTS2 confirmed a similar trend to the microarray results. Interestingly absolute number of Tregs, and Th2/Treg ratio were higher in 10 IST responsive patients compared to 5 non-responsive patients (p=0.005 and 0.02, respectively). We show that expansion of Th1, Th2, Th17, and decreased/skewed Tregs immunophenotype and function are a consistent and defining feature of SAA and VSAA. Clonal expansion of Th1 cells is likely to be antigen driven and the presence of dysfunctional Tregs aggravates this autoimmune response. Increases of Tregs, and Th2/Treg ratios following IST predicts a favourable response to this treatment. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Circulating and gut-resident human Th17 cells express CD161 and promote intestinal inflammation

Journal of Experimental Medicine ◽

10.1084/jem.20081712 ◽

2009 ◽

Vol 206 (3) ◽

pp. 525-534 ◽

Cited By ~ 329

Author(s):

Melanie A. Kleinschek ◽

Katia Boniface ◽

Svetlana Sadekova ◽

Jeff Grein ◽

Erin E. Murphy ◽

...

Keyword(s):

T Cells ◽

Cd4 T Cells ◽

Th17 Cells ◽

Intestinal Inflammation ◽

Interferon Γ ◽

Intestinal Cells ◽

T Helper ◽

T Helper 17 ◽

Inflammatory Stimuli ◽

Cc Chemokine Receptor 6

The C-type lectin-like receptor CD161, which has recently been described to promote T cell expansion, is expressed on a discrete subset of human CD4 T cells. The function of such cells, however, has remained elusive. We now demonstrate that CD161+ CD4 T cells comprise a circulating and gut-resident T helper 17 (Th17) cell population. During Crohn's disease (CD), these CD161+ cells display an activated Th17 phenotype, as indicated by increased expression of interleukin (IL)-17, IL-22, and IL-23 receptor. CD161+ CD4 T cells from CD patients readily produce IL-17 and interferon γ upon stimulation with IL-23, whereas, in healthy subjects, priming by additional inflammatory stimuli such as IL-1β was required to enable IL-23–induced cytokine release. Circulating CD161+ Th17 cells are imprinted for gut homing, as indicated by high levels of CC chemokine receptor 6 and integrin β7 expression. Supporting their colitogenic phenotype, CD161+ Th17 cells were found in increased numbers in the inflammatory infiltrate of CD lesions and induced expression of inflammatory mediators by intestinal cells. Our data identify CD161+ CD4 T cells as a resting Th17 pool that can be activated by IL-23 and mediate destructive tissue inflammation.

Download Full-text

HuR Plays a Positive Role to Strengthen the Signaling Pathways of CD4+ T Cell Activation and Th17 Cell Differentiation

Journal of Immunology Research ◽

10.1155/2021/9937243 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Shiguang Yu ◽

Morgan Tripod ◽

Ulus Atasoy ◽

Jing Chen

Keyword(s):

T Cells ◽

T Cell ◽

Signaling Pathways ◽

T Cell Activation ◽

Cd4 T Cells ◽

Th17 Cell ◽

Th17 Cells ◽

Cell Activation ◽

Cd4 T Cell ◽

Th17 Cell Differentiation

After antigen and/or different cytokine stimulation, CD4+ T cells activated and differentiated into distinct T helper (Th) cells via differential T cell signaling pathways. Transcriptional regulation of the activation and differentiation of naïve CD4+ T cells into distinct lineage Th cells such as Th17 cells has been fully studied. However, the role of RNA-binding protein HuR in the signaling pathways of their activation and differentiation has not been well characterized. Here, we used HuR conditional knockout (HuR KO) CD4+ T cells to study mechanisms underlying HuR regulation of T cell activation and differentiation through distinct signaling pathways. Our work showed that, mechanistically, HuR positively promoted CD3g expression by binding its mRNA and enhanced the expression of downstream adaptor Zap70 and Malt1 in activated CD4+ T cells. Compared to WT Th0 cells, HuR KO Th0 cells with reduced Bcl-2 expression are much more susceptible to apoptosis than WT Th0 cells. We also found that HuR stabilized IL-6Rα mRNA and promoted IL-6Rα protein expression, thereby upregulating its downstream phosphorylation of Jak1 and Stat3 and increased level of phosphorylation of IκBα to facilitate Th17 cell differentiation. However, knockout of HuR increased IL-22 production in Th17 cells, which was due to HuR deficiency in reducing IL-22 transcription repressor c-Maf expression. These results highlight the importance of HuR in TCR signaling and IL-6/IL-6R axis driving naïve CD4+ T cell activation and differentiation into Th17 cells.

Download Full-text