RORγt Activity Research Articles

Discovery of novel and potent sulfonamide derivatives as orally available drug for psoriasis

The retinoid-related orphan receptor gamma-t (RORγt), a member of the nuclear receptor superfamily, functions as a ligand-dependent transcription factor. As a pivotal modulator in the development and functionality of T-helper 17 (Th17) cells, RORγt plays a crucial role in immune response regulation. Inverse agonists targeting RORγt demonstrate significant potential in modulating Th17 cell activity, offering a promising avenue for the development of therapeutics aimed at treating autoimmune diseases associated with Th17 dysregulation. GSK2981278 is a potent RORγt inverse agonist, but a drawback of GSK2981278 is its low pharmacokinetic profile, leading to a clinical failure. We have explored detailed structure–activity relationship of GSK2981278 trying to improve metabolic stability while maintaining RORγt activity. As a result, a novel series of sulfonamide derivatives was discovered as potent RORγt inverse agonists with improved drug-like properties. b14 had greatly improved In Vitro metabolic stability (T1/2 = 36.2 min) compared to GSK2981278 (T1/2 = 0.8 min). Oral dosing of compound b14 resulted in a dose-dependent suppression of IL-17A cytokine levels within a murine model of imiquimod-induced skin inflammation, underscoring its potential as a therapeutic intervention.

Lipid metabolism: a central modulator of RORγt-mediated Th17 cell differentiation.

Among the T helper cell subsets, Th17 cells contribute to the development of various inflammatory and autoimmune diseases, including psoriasis, rheumatoid arthritis, inflammatory bowel disease, steroid-resistant asthma, and multiple sclerosis. Retinoid-related orphan receptor gamma t (RORγt), a nuclear hormone receptor, serves as a master transcription factor for Th17 cell differentiation. Recent findings have shown that modulating the metabolic pathway is critical for Th17 cell differentiation, particularly through the engagement of de novo lipid biosynthesis. Suppression of lipid biosynthesis, either through the pharmacological inhibition or gene deletion of related enzymes in CD4+ T cells, results in significant impairment of Th17 cell differentiation. Mechanistic studies indicate that metabolic fluxes through both the fatty acid and cholesterol biosynthetic pathways have a pivotal role in the regulation of RORγt activity through the generation of endogenous RORγt lipid ligands. This review discusses recent discoveries highlighting the importance of lipid metabolism in Th17 cell differentiation and function, as well as exploring specific molecular pathways involved in RORγt activation through cellular lipid metabolism. We further elaborate on a pioneering therapeutic approach to improve inflammatory and autoimmune disorders via the inhibition of RORγt.

1-Oleoyl-lysophosphatidylethanolamine stimulates RORγt activity in TH17 cells.

Metabolic fluxes involving fatty acid biosynthesis play essential roles in controlling the differentiation of T helper 17 (TH17) cells. However, the exact enzymes and lipid metabolites involved, as well as their link to promoting the core gene transcriptional signature required for the differentiation of TH17 cells, remain largely unknown. From a pooled CRISPR-based screen and unbiased lipidomics analyses, we identified that 1-oleoyl-lysophosphatidylethanolamine could act as a lipid modulator of retinoid-related orphan receptor gamma t (RORγt) activity in TH17 cells. In addition, we specified five enzymes, including Gpam, Gpat3, Lplat1, Pla2g12a, and Scd2, suggestive of the requirement of glycerophospholipids with monounsaturated fatty acids being required for the transcription of Il17a. 1-Oleoyl-lysophosphatidylethanolamine was reduced in Pla2g12a-deficient TH17 cells, leading to the abolition of interleukin-17 (IL-17) production and disruption to the core transcriptional program required for the differentiation of TH17 cells. Furthermore, mice with T cell-specific deficiency of Pla2g12a failed to develop disease in an experimental autoimmune encephalomyelitis model of multiple sclerosis. Thus, our data indicate that 1-oleoyl-lysophosphatidylethanolamine is a lipid metabolite that promotes RORγt-induced TH17 cell differentiation and the pathogenicity of TH17 cells.

Pak2-mediated phosphorylation promotes RORγt ubiquitination and inhibits colonic inflammation

Abstract Dysregulated Interleukin (IL)-17 expression and its downstream signaling is strongly linked to inflammatory bowel diseases (IBD). However, the molecular mechanisms by which the function of RORγt, the transcription factor of IL-17, is regulated remains elusive, which is absolutely necessary to develop advanced strategies to inhibit IL-17-mediated inflammation. By mass spectrometry-based approach, we have identified that Pak2, a Ser/Thr kinase, directly associates with RORγt. Pak2 recognizes a conserved KRLS motif within RORγt and phosphorylated the Serine (S) 316 within this motif. Genetic deletion of Pak2 in Th17 cells resulted in reduced RORγt phosphorylation, increased IL-17 expression and severe colitis upon adoptive transfer to Rag1 −/−mice. Similarly, reconstitution of RORγt-S316A mutant in Rorc −/−Th17 cells resulted in enhanced IL-17 expression and colitis severity. Mechanistically, we demonstrate that Pak2-mediated phosphorylation causes a conformational change resulting in exposure of the ubiquitin ligase Itch interacting PPLY motif and degradation of RORγt. Thus, we have uncovered a novel mechanism by which the activity of RORγt is regulated that can be exploited therapeutically. This work was supported by funds from the National Institutes of Health (R01-DK115668 and R01-AI155786) and Cancer Prevention Research Institute of Texas (RP160577 and RP190527), a translational pilot project grant from the Harold C. Simmons Comprehensive Cancer Center, UT Southwestern Medical Center (23001045) to K.V., and R01-DK117001 to K.V. and A.L.T.

Virtual Screening Strategy to Identify Retinoic Acid-Related Orphan Receptor γt Modulators.

Molecular docking is a key method used in virtual screening (VS) campaigns to identify small-molecule ligands for drug discovery targets. While docking provides a tangible way to understand and predict the protein-ligand complex formation, the docking algorithms are often unable to separate active ligands from inactive molecules in practical VS usage. Here, a novel docking and shape-focused pharmacophore VS protocol is demonstrated for facilitating effective hit discovery using retinoic acid receptor-related orphan receptor gamma t (RORγt) as a case study. RORγt is a prospective target for treating inflammatory diseases such as psoriasis and multiple sclerosis. First, a commercial molecular database was flexibly docked. Second, the alternative docking poses were rescored against the shape/electrostatic potential of negative image-based (NIB) models that mirror the target's binding cavity. The compositions of the NIB models were optimized via iterative trimming and benchmarking using a greedy search-driven algorithm or brute force NIB optimization. Third, a pharmacophore point-based filtering was performed to focus the hit identification on the known RORγt activity hotspots. Fourth, free energy binding affinity evaluation was performed on the remaining molecules. Finally, twenty-eight compounds were selected for in vitro testing and eight compounds were determined to be low μM range RORγt inhibitors, thereby showing that the introduced VS protocol generated an effective hit rate of ~29%.

USP1-regulated reciprocal differentiation of Th17 cells and Treg cells by deubiquitinating and stabilizing TAZ.

The balance between inflammatory T helper type 17 (Th17) and immunosuppressive regulatory T (Treg) cells is critical for maintaining immune homeostasis in the human body and is tightly regulated under healthy conditions. An increasing number of studies have reported that deubiquitinases (DUBs) play a vital role in regulating Th17- and Treg-cell differentiation. However, the biological functions of only a small fraction of DUBs in Th17- and Treg-cell differentiation are well defined. In this study, we identified ubiquitin-specific peptidase 1 (USP1) as a vital regulator of CD4+ T-cell differentiation. USP1 promoted Th17-cell differentiation but attenuated Treg-cell differentiation, thereby promoting the development of inflammatory diseases. Mechanistically, USP1 in CD4+ T cells enhanced the activity of RORγt but promoted the proteasomal degradation of Foxp3 through deubiquitination and stabilization of TAZ in vitro and in vivo. Notably, ML323, a specific inhibitor of the USP1/UAF1 deubiquitinase complex, inhibited Th17-cell differentiation and promoted Treg-cell differentiation in vitro and in vivo, indicating that ML323 might be a promising candidate for the treatment of diseases associated with an imbalance between Th17 and Treg cells. Our study highlights the critical role of USP1 in regulating adaptive immune responses and suggests that USP1 might be a drug target for the treatment of diseases associated with an imbalance between Th17 and Treg cells.

Pak2-mediated phosphorylation promotes RORγt ubiquitination and inhibits colonic inflammation.

SUMMARYDysregulated interleukin-17 (IL-17) expression and its downstream signaling is strongly linked to inflammatory bowel diseases (IBDs). However, the molecular mechanisms by which the function of RORγt, the transcription factor of IL-17, is regulated remains elusive. By a mass spectrometry-based approach, we identify that Pak2, a serine (S)/threonine (T) kinase, directly associates with RORγt. Pak2 recognizes a conserved KRLS motif within RORγt and phosphorylates the S-316 within this motif. Genetic deletion of Pak2 in Th17 cells reduces RORγt phosphorylation, increases IL-17 expression, and induces severe colitis upon adoptive transfer to Rag1−/− mice. Similarly, reconstitution of RORγt-S316A mutant in Rorc−/− Th17 cells enhances IL-17 expression and colitis severity. Mechanistically, we demonstrate that Pak2-mediated phosphorylation causes a conformational change resulting in exposure of the ubiquitin ligase Itch interacting PPLY motif and degradation of RORγt. Thus, we have uncovered a mechanism by which the activity of RORγt is regulated that can be exploited therapeutically.

STING is an intrinsic checkpoint inhibitor that restrains the TH17 cell pathogenic program.

SUMMARYExternal and intrinsic factors regulate the transcriptional profile of T helper 17 (TH17) cells, thereby affecting their pathogenic potential and revealing their context-dependent plasticity. The stimulator of interferon genes (STING), a component of the intracellular DNA-sensing pathway, triggers immune responses but remains largely unexplored in T cells. Here, we describe an intrinsic role of STING in limiting the TH17 cell pathogenic program. We demonstrate that non-pathogenic TH17 cells express higher levels of STING than those activated under pathogenic conditions. Activation of STING induces interleukin-10 (IL-10) production in TH17 cells, decreasing IL-17A and IL-23R expression in a type I interferon (IFN)-independent manner. Mechanistically, STING-induced IL-10 production partially requires aryl hydrocarbon receptor (AhR) signaling, while the decrease of IL-17A expression occurs due to a reduction of Rorγt transcriptional activity. Our findings reveal a regulatory function of STING in the TH17 cell activation program, proposing it as a valuable target to limit TH17-cell-mediated inflammation.

2′, 4′-Dihydroxy-2,3-dimethoxychalcone: A pharmacological inverse agonist of RORγt ameliorating Th17-driven inflammatory diseases by regulating Th17/Treg

Multiple sclerosis, inflammatory bowel disease and organ transplant rejection are related to Th17 cell development and inflammatory respond. RORγt, a specific transcription factor regulating Th17 cell differentiation, is a pivotal target for the treatment of diseases. However, the clinical application of RORγt inverse agonists reported so far has been hindered due to limited efficacy and toxic side effects. Plant-derived natural products with drug-like properties and safety are wide and valuable resources for candidate drug discovery. Herein, structure-based virtual screening was used to find out 2′,4′-Dihydroxy-2,3-dimethoxychalcone (DDC), a chalcone derivative rich in plants and food, located in the binding pocket of RORγt and targeted to inhibit RORγt activity. DDC repressed murine Th17 differentiation and promoted Treg differentiation remarkably in a dose-dependent manner. In addition, DDC treatment improved experimental autoimmune encephalomyelitis recovery, ameliorated experimental colitis severity, and prevented graft rejection significantly. Mechanically, DDC indirectly stabilized Foxp3 expression by inhibiting RORγt activity and the expression of its target gene profile in vitro and in vivo, which realized its regulation of Th17/Treg balance. In conclusion, our study provides a scientific basis that DDC, as an inverse agonist of RORγt with simple structure, rich sources, low cost, high efficiency, and low toxicity, has great potential for the development of a novel effective immunomodulator for the treatment of Th17-mediated inflammatory diseases.

Role of T-lymphocytes in Kidney Disease.

BackgroundThe role of T-regulatory cells (Tregs) in inflammatory renal disease is not yet established. We attempted to study peripherally circulating T-cells expressing RORγt+Foxp3+ dynamics in acute kidney injury (AKI) and chronic kidney disease (CKD).AimTo determine the role of T-regulatory cells in AKI and CKD.Research methodology This is a cross-sectional study conducted between January 2019 to January 2021 at a single tertiary care centre in Pune, India. Candidates enrolled in the study were either patients with CKD not on maintenance hemodialysis or newly diagnosed cases of AKI. Kidney transplant recipients, patients with autoimmune diseases like systemic lupus erythematosus (SLE), IgA nephropathy, or those receiving immuno-suppressants were excluded. T-lymphocytes were analyzed using a flow cytometer. ResultsWe studied 80 patients with kidney injury, 40 each belonging to the AKI and CKD study groups and 10 healthy volunteers as controls. The rationale behind having a small control group was to merely get an idea of T helper 17 (Th17):Treg ratio and different immune cell-phenotype profiles in healthy volunteers without kidney injury, diabetes, hypertension or any other risk factors. The ratio of RORγt:Foxp3 was ≤ 1 in these individuals (control group) while this ratio was significantly altered (MFI RORγt:Foxp3 ≥1) in the AKI/CKD study arm. We examined peripherally circulating T-lymphocytes in acute kidney injury and chronic kidney disease, comparing their activity to healthy volunteers. Biopsy-proven kidney injury patients (29/80) were also included in this study. We found that the ratio of RORγt:Foxp3 was altered in patients with kidney injury (acute and chronic) and was statistically significant compared to controls, indicating that injury may be attributed to T-cell dysfunction. ConclusionOur study provides some evidence of T-cell dysfunction in the pathology of kidney injury in acute and chronic kidney disease via activity of Foxp3 and RORγt. We found that there is evidence of altered Th17/Treg activity in kidney injury, more prevalent in acute than chronic, when compared to healthy volunteers.

Genetic and pharmacological inhibition of the nuclear receptor ROR\u03b1 regulates TH17 driven inflammatory disorders

Full development of IL-17 producing CD4+ T helper cells (TH17 cells) requires the transcriptional activity of both orphan nuclear receptors RORα and RORγt. However, RORα is considered functionally redundant to RORγt; therefore, the function and therapeutic value of RORα in TH17 cells is unclear. Here, using mouse models of autoimmune and chronic inflammation, we show that expression of RORα is required for TH17 cell pathogenicity. T-cell-specific deletion of RORα reduces the development of experimental autoimmune encephalomyelitis (EAE) and colitis. Reduced inflammation is associated with decreased TH17 cell development, lower expression of tissue-homing chemokine receptors and integrins, and increased frequencies of Foxp3+ T regulatory cells. Importantly, inhibition of RORα with a selective small molecule antagonist mostly phenocopies our genetic data, showing potent suppression of the in vivo development of both chronic/progressive and relapsing/remitting EAE, but with no effect on overall thymic cellularity. Furthermore, use of the RORα antagonist effectively inhibits human TH17 cell differentiation and memory cytokine secretion. Together, these data suggest that RORα functions independent of RORγt in programming TH17 pathogenicity and identifies RORα as a safer and more selective therapeutic target for the treatment of TH17-mediated autoimmunity.

Discovery of tetrahydroquinolines and benzomorpholines as novel potent RORγt agonists.

The retinoic acid receptor-related orphan receptor γt (RORγt) is an important nuclear receptor that regulates the differentiation of Th17cells and production of interleukin 17(IL-17). RORγt agonists increase basal activity of RORγt and could provide a potential approach to cancer immunotherapy. Herein, hit compound 1 was identified as a weak RORγt agonist during in-house library screening. Changes in LHS core of 1 led to the identification of tetrahydroquinoline compound 6 as a partial RORγt agonist (max. act.=39.3%). Detailed structure-activity relationship on substituent of the LHS core, amide linker and RHS arylsulfonyl moiety was explored and a novel series of tetrahydroquinolines and benzomorpholines was discovered as potent RORγt agonists. Tetrahydroquinoline compound 8g (EC50=8.9±0.4nM, max. act.=104.5%) and benzomorpholine compound 9g (EC50=7.5±0.6nM, max. act.=105.8%) were representative compounds with high RORγt agonistic activity in dual FRET assay, and they showed good activity in cell-based Gal4 reporter gene assay and Th17cell differentiation assay (104.5% activation at 300nM of 8g; 59.4% activation at 300nM of 9g). The binding modes of 8g and 9g as well as the two RORγt inverse agonists accidentally discovered were also discussed.

Discovery of carboxyl-containing biaryl ureas as potent RORγt inverse agonists

GSK805 (1) is a potent RORγt inverse agonist, but a drawback of 1 is its low solubility, leading to a limited absorption in high doses. We have explored detailed structure-activity relationship on the amide linker, biaryl and arylsulfonyl moieties of 1 trying to improve solubility while maintaining RORγt activity. As a result, a novel series of carboxyl-containing biaryl urea derivatives was discovered as potent RORγt inverse agonists with improved drug-like properties. Compound 3i showed potent RORγt inhibitory activity and subtype selectivity with an IC50 of 63.8 nM in RORγ FRET assay and 85 nM in cell-based RORγ-GAL4 promotor reporter assay. Reasonable inhibitory activity of 3i was also achieved in mouse Th17 cell differentiation assay (76% inhibition at 0.3 μM). Moreover, 3i had greatly improved aqueous solubility at pH 7.4 compared to 1, exhibited decent mouse PK profile and demonstrated some in vivo efficacy in an imiquimod-induced psoriasis mice model.

Ligand-Based Design of Allosteric Retinoic Acid Receptor-Related Orphan Receptor γt (RORγt) Inverse Agonists.

Retinoic acid receptor-related orphan receptor γt (RORγt) is a nuclear receptor associated with the pathogenesis of autoimmune diseases. Allosteric inhibition of RORγt is conceptually new, unique for this specific nuclear receptor, and offers advantages over traditional orthosteric inhibition. Here, we report a highly efficient in silico-guided approach that led to the discovery of novel allosteric RORγt inverse agonists with a distinct isoxazole chemotype. The the most potent compound, 25 (FM26), displayed submicromolar inhibition in a coactivator recruitment assay and effectively reduced IL-17a mRNA production in EL4 cells, a marker of RORγt activity. The projected allosteric mode of action of 25 was confirmed by biochemical experiments and cocrystallization with the RORγt ligand binding domain. The isoxazole compounds have promising pharmacokinetic properties comparable to other allosteric ligands but with a more diverse chemotype. The efficient ligand-based design approach adopted demonstrates its versatility in generating chemical diversity for allosteric targeting of RORγt.

The Inhibitory Effects of Pentacyclic Triterpenes from Loquat Leaf against Th17 Differentiation

ABSTRACT Background Loquat leaf is an herb that is commonly used in traditional Chinese medicine (TCM) for its anti-inflammatory properties. Numerous studies have demonstrated that Th17 cells play a fundamental role in mediating SLE pathological deterioration. In our study, we investigated the inhibitory effect of pentacyclic triterpenes from loquat leaf on T helper 17 (Th17) cells and the therapeutic efficacy of OA in Lupus nephritis (LN) development. Methods We isolated three pentacyclic triterpene compounds rom loquat leaf by bioassay-directed fractionation and separation method. There were methyl corosolate (MC), uvaol (UL), and oleanolic acid (OA) Firstly, we elucidated Retinoic acid receptor-related orphan receptor gamma t (RORγt) inhibitory activity of these three compounds in the cell-based assay and Th17 differentiation in vitro assay. Then, we used OA-treated pristine-induced LN mice to evaluate the therapeutic effects of OA in LN development. Anti-dsDNA level in serum was detected by enzyme-linked immunosorbent assay (ELISA), interleukin 17A (IL-17A) and interferon-γ (IFN-γ) expression in spleen cells by Flow cytometry (FCM), histomorphologic examination of kidneys were performed by periodic acid schiff (PAS) staining and immunofluorescence analysis. Results Pentacyclic triterpene compounds (MC, UL, OA) displayed inhibition of RORγt activity in cell-based assay and Th17 differentiation in vitro. Furthermore, our results also showed that OA could significantly decrease serum anti-dsDNA antibody levels, IL-17A and IFN-γ expression and alleviate renal pathological damage in OA-treated group mice than in the model group mice. Conclusion These results demonstrated that OA can improve the clinical manifestation of LN, indicating potential application in SLE therapy.

C-Maf regulates the plasticity of group 3 innate lymphoid cells by restraining the type 1 program.

CCR6- group 3 innate lymphoid cells (ILC3s) are mediators of intestinal immunity and barrier function that possess the capacity to acquire type 1 effector features and fully convert into ILC1s. The molecular mechanisms governing such plasticity are undefined. Here, we identified c-Maf as an essential regulator of ILC3 homeostasis and plasticity that limits physiological ILC1 conversion. Phenotypic analysis of effector status in Maf-deficient CCR6- ILC3s, coupled with evaluation of global changes in transcriptome, chromatin accessibility, and transcription factor motif enrichment, revealed that c-Maf enforces ILC3 identity. c-Maf promoted ILC3 accessibility and supported RORγt activity and expression of type 3 effector genes. Conversely, c-Maf antagonized type 1 programming, largely through restraint of T-bet expression and function. Mapping of the dynamic changes in chromatin landscape accompanying CCR6- ILC3 development and ILC1 conversion solidified c-Maf as a gatekeeper of type 1 regulatory transformation and a controller of ILC3 fate.

(Inverse) Agonists of Retinoic Acid-Related Orphan Receptor γ: Regulation of Immune Responses, Inflammation, and Autoimmune Disease.

Retinoic acid-related orphan receptor γt (RORγt) functions as a ligand-dependent transcription factor that regulates multiple proinflammatory genes and plays a critical role in several inflammatory and autoimmune diseases. Various endogenous and synthetic RORγ (inverse) agonists have been identified that regulate RORγ transcriptional activity, including many cholesterol intermediates and oxysterols. Changes in cholesterol biosynthesis and metabolism can therefore have a significant impact on the generation of oxysterol RORγ ligands and, consequently, can control RORγt activity and inflammation. These observations contribute to a growing literature that connects cholesterol metabolism to the regulation of immune responses and autoimmune disease. Loss of RORγ function in knockout mice and in mice treated with RORγ inverse agonists results in reduced production of proinflammatory cytokines, such as IL-17A/F, and increased resistance to autoimmune disease in several experimental rodent models. Thus, RORγt inverse agonists might provide an attractive therapeutic approach to treat a variety of autoimmune diseases.

3β-Acetyloxy-oleanolic Acid Attenuates Pristane-Induced Lupus Nephritis by Regulating Th17 Differentiation.

Th17 activity has been implicated in systemic lupus erythematosus (SLE), which is a systemic autoimmune disease with a typical clinical manifestation of lupus nephritis (LN). Retinoic acid receptor-related orphan receptor gamma t (RORγt) has been shown to be important for Th17 differentiation. In this study, we evaluated the inhibition of RORγt activity by 3β-acetyloxy-oleanolic acid (AOA), a small molecule isolated from the root of Symplocos laurina, a traditional herb belonging to South China. We demonstrated that AOA can inhibit RORγt activity and prevent SLE pathogenesis in a pristane-induced LN model. The results showed that AOA decreased RORγt transcription activity in a reporter assay and prevented Th17 differentiation in vitro. In vivo studies showed that AOA treatment decreased serum anti-dsDNA antibody and alleviated renal pathologic damage as well as antibody complex accumulation in the pristane-induced LN model. These results demonstrated that AOA can improve the clinical manifestation of LN, indicating potential application in SLE therapy.

Acupoint injection improves allergic rhinitis by balancing Th17/Treg in allergic rhinitis rats

To observe the effect of acupoint injection on expression of fork head/winged helix protein 3 (Foxp3), retinoic acid-related orphan receptor γt (RORγt) in nasal mucosa and serum interleukin-17 (IL-17) level in allergic rhinitis (AR) rats, so as to explore its mechanism underlying improvement of AR in terms of balancing Th17/Treg. Thirty-two SD rats (half male and half female) were randomized into normal control, AR model, acupoint injection and non-acupoint injection groups (n＝8 in each group). The AR model was established by ovalbumin sensitization. In the acupoint injection group, "Yintang" (EX-HN3) and bilateral "Yingxiang"(LI20) were selected for injection of mixture solution of dexamethasone (DEX) and transfer factor and lidocaine (0.1 mL/acupoint), once every 3 days for a total of 4 times. The non-acupoints, located at the mid-point between the "Houhai" (GV1) and "Huantiao"(GB30) on the bilateral hips and the sites 5 cm inferior to the axillary were injected with the same dose of mixture solution as that in the acupoint injection. The AR severity was assessed by cumulative quantification scoring methods (including the numbers of nose-catching and sneezes, and the amount of nasal secretions in 30 min). The expressions of Foxp3 and RORγt in the nasal mucosa were detected by immunohistochemistry. The serum IL-17 content was detected by enzyme linked immunosorbent assay (ELISA)．. The AR symptom score and serum IL-17 content were significantly higher in the AR model group than those in the normal control group (P<0.05), and significantly down-regulated in the acupoint injection group (not in the non-acupoint group) relevant to the AR model group (P<0.05). Following modeling, the expression levels of nasal Foxp3 protein was significantly down-regulated while that of RORγt protein markedly up-regulated in the AR model group relevant to the normal control group (P<0.05), indicating an imbalance between Foxp3 and RORγt activity(P<0.05). After EA intervention, the increased expression of Foxp3 and the down-regulated expression of RORγt were revised in the acupoint injection group (P<0.05) but not in the non-acupoint group (P>0.05). The percentage of the Foxp3 positive cells and the ratio of Foxp3/RORγt were negatively correlated with the AR symptom score(P<0.05), the expression of RORγt and the content of IL-17 were positively correlated with the symptom score (P<0.05)．. Acupoint injection is able to improve symptoms of RA rats, which may be related with its function in up-regulating the level of nasal mucosal Foxp3 and suppressing the levels of nasal RORγt and serum IL-17 to correct the imbalance of Th17/Treg.

Antagonizing Retinoic Acid-Related-Orphan Receptor Gamma Activity Blocks the T Helper 17/Interleukin-17 Pathway Leading to Attenuated Pro-inflammatory Human Keratinocyte and Skin Responses.

The nuclear hormone receptor retinoic acid receptor-related-orphan-receptor-gamma t (RORγt) is the key transcription factor required for Th17 cell differentiation and for production of IL-17 family cytokines by innate and adaptive immune cells. Dysregulated Th17 immune responses have been associated with the pathogenesis of several inflammatory and autoimmune diseases such as psoriasis, psoriatic arthritis, and ankylosing spondylitis. In this article, we describe the in vitro pharmacology of a potent and selective low molecular weight RORγt inhibitor identified after a structure-based hit-to-lead optimization effort. The compound interfered with co-activator binding to the RORγt ligand binding domain and impaired the transcriptional activity of RORγt as evidenced by blocked IL-17A secretion and RORE-mediated transactivation of a luciferase reporter gene. The inhibitor effectively reduced IL-17A production by human naive and memory T-cells and attenuated transcription of pro-inflammatory Th17 signature genes, such as IL17F, IL22, IL26, IL23R, and CCR6. The compound selectively suppressed the Th17/IL-17 pathway and did not interfere with polarization of other T helper cell lineages. Furthermore, the inhibitor was selective for RORγt and did not modify the transcriptional activity of the closely related family members RORα and RORβ. Using human keratinocytes cultured with supernatants from compound treated Th17 cells we showed that pharmacological inhibition of RORγt translated to suppressed IL-17-regulated gene expression in keratinocyte cell cultures. Furthermore, in ex vivo immersion skin cultures our RORγt inhibitor suppressed IL-17A production by Th17-skewed skin resident cells which correlated with reduced human β defensin 2 expression in the skin. Our data suggests that inhibiting RORγt transcriptional activity by a low molecular weight inhibitor may hold utility for the treatment of Th17/IL-17-mediated skin pathologies.