Pharmacological inhibitory profile of TAK-828F, a potent and selective orally available RORγt inverse agonist

Small-molecule agents for treating skin diseases

Skin diseases are a class of common and frequently occurring diseases that significantly impact daily lives. Currently, the limited effective therapeutic drugs are far from meeting the clinical needs; most drugs typically only provide symptomatic relief rather than a cure. Developing small-molecule drugs with improved efficacy holds paramount importance for treating skin diseases. This review aimed to systematically introduce the pathogenesis of common skin diseases in daily life, list related drugs applied in the clinic, and summarize the clinical research status of candidate drugs and the latest research progress of candidate compounds in the drug discovery stage. Also, it statistically analyzed the number of publications and global attention trends for the involved skin diseases. This review might provide practical information for researchers engaged in dermatological drugs and further increase research attention to this disease area.

Small molecule inhibitors of RORγt for Th17 regulation in inflammatory and autoimmune diseases

As a ligand-dependent transcription factor, retinoid-associated orphan receptor γt (RORγt) that controls T helper (Th) 17 cell differentiation and interleukin (IL)-17 expression plays a critical role in the progression of several inflammatory and autoimmune conditions. An emerging novel approach to the therapy of these diseases thus involves controlling the transcriptional capacity of RORγt to decrease Th17 cell development and IL-17 production. Several RORγt inhibitors including both antagonists and inverse agonists have been discovered to regulate the transcriptional activity of RORγt by binding to orthosteric- or allosteric-binding sites in the ligand-binding domain. Some of small-molecule inhibitors have entered clinical evaluations. Therefore, in current review, the role of RORγt in Th17 regulation and Th17-related inflammatory and autoimmune diseases was highlighted. Notably, the recently developed RORγt inhibitors were summarized, with an emphasis on their optimization from lead compounds, efficacy, toxicity, mechanisms of action, and clinical trials. The limitations of current development in this area were also discussed to facilitate future research.

SMURF1 inhibits the Th17 and Th17.1 polarization and improves the Treg/Th17 imbalance in systemic lupus erythematosus through the ubiquitination of RORγt

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease. This study aimed to investigate the role of SMAD specific E3 ubiquitin protein ligase 1 (SMURF1) in the Th17 and Th17.1 differentiation and Treg/Th17 imbalance, which are major factors contributing to the pathogenesis of SLE. SLE patients and healthy individuals were recruited to detect the SMURF1 levels in naïve CD4⁺ cells from peripheral blood. Purified and expanded naïve CD4⁺ T cells were employed to evaluate the effects of SMURF1 on Th17 and Th17.1 polarization in vitro. MRL/lpr lupus model was employed to explore the disease phenotype as well as Treg/Th17 balance in vivo. The results showed that SMURF1 was down-regulated in naïve CD4⁺ T cells in peripheral blood of patients with SLE and in spleen of MRL/lpr mice. SMURF1 overexpression suppressed the polarization of naïve CD4⁺ T cells toward Th17 and Th17.1 phenotype and down-regulated the expression of retinoid-related orphan receptor-gammat (RORγt). Subsequently, SMURF1 down-regulation aggravated the disease phenotype, inflammation, and the Treg/Th17 imbalance in MRL/lpr mice. Furthermore, we found that SMURF overexpression promoted the ubiquitination and decreases the stability of RORγt. In conclusion, SMURF1 inhibited the polarization of Th17 and Th17.1 cells and improved the Treg/Th17 imbalance in SLE, which was mediated as least partly by the ubiquitination of RORγt.

Targeting Lineage-Specific Transcription Factors and Cytokines of the Th17/Treg Axis by Novel 1,3,4-Oxadiazole Derivatives of Pyrrolo[3,4-d]pyridazinone Attenuates TNBS-Induced Experimental Colitis

The pharmacotherapy of inflammatory bowel disease (IBD) is still not fully effective and safe. Attempts to search for new IBD drugs remain an incessant research aim. One of the novel approaches is targeting the developmental pathway molecules and effector cytokines of Th17/Treg axis. This study aimed to elucidate the impact of new pyrrolo[3,4-d]pyridazinone derivatives, compounds 7b, 10b, or 13b, on the course of experimental colitis in rats and to assess whether these new compounds may influence Th17/Treg axis. Rats were pretreated with studied compounds intragastrically before intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid used for colitis induction. Body weight loss, disease activity index, colon index, and colon tissue damage were analyzed to evaluate the severity of colitis. The colonic levels of RORγt, STAT3, CCR6, Foxp3, IL-6, IL-10, IL-17, TNF-α, IL-23, and PGE₂ were assessed. Pretreatment with compounds 7b and 13b alleviated the severity of colitis and concomitantly counteracted the increased levels of RORγt, STAT3, CCR6, IL-6, IL-17, IL-23, TNF-α, and PGE₂. The beneficial effect of compounds 7b and 13b may be due to the decrease in the levels of Th17-specific transcription factors and cytokines. The studied compounds might therefore constitute a promising therapeutic strategy in Th17/Treg imbalance-driven inflammatory conditions such as IBD.

Role of Interleukin-17 in Acute Pancreatitis

Acute pancreatitis (AP) is a leading cause of death and is commonly accompanied by systemic manifestations that are generally associated with a poor prognosis. Many cytokines contribute to pancreatic tissue damage and cause systemic injury. Interleukin-17 (IL-17) is a cytokine that may play a vital role in AP. Specifically, IL-17 has important effects on the immune response and causes interactions between different inflammatory mediators in the AP-related microenvironment. In this literature review, we will discuss the existing academic understanding of IL-17 and the impacts of IL-17 in different cells (especially in acinar cells and immune system cells) in AP pathogenesis. The clinical significance and potential mechanisms of IL-17 on AP deterioration are emphasized. The evidence suggests that inhibiting the IL-17 cytokine family could alleviate the pathogenic process of AP, and we highlight therapeutic strategies that directly or indirectly target IL-17 cytokines in acute pancreatitis.

Diastereoselective Synthesis of a cis-1,3-Disubstituted Cyclobutane Carboxylic Acid Scaffold for TAK-828F, a Potent Retinoic Acid Receptor-Related Orphan Receptor (ROR)-γt Inverse Agonist

A scalable synthesis of the cis-1,3-disubstituted cyclobutane carboxylic acid scaffold of TAK-828F (1) has been developed, featuring the diastereoselective reduction of a cyclobutylidene Meldrum's acid derivative with NaBH₄. Controlling acidic impurities was crucial for improving the diastereomeric ratio by recrystallization. Furthermore, reaction optimization and the streamlining of several steps established a scalable synthetic method free from column chromatography purification with an overall yield improved from 23 to 39%.

Agonist Lock Touched and Untouched Retinoic Acid Receptor-Related Orphan Receptor-γt (RORγt) Inverse Agonists: Classification Based on the Molecular Mechanisms of Action

Retinoic acid receptor-related orphan receptor-gamma-t (RORγt) is a potential drug target for autoimmune diseases with a clear biological mechanism in the Th17/IL-17 pathway. The "agonist lock", which is formed by residues His479-Tyr502-Phe506 in RORγt, makes H12 tightly contact H11 in a suitable conformation for coactivator binding and, thus, is related to RORγt transcriptional activation. The inverse agonism of RORγt is complex because not all RORγt inverse agonists directly break the agonist lock to interfere with coactivator recruitment and the transcription of RORγt. Here, we analyze the complex structures, binding modes, and biological activities of various RORγt inverse agonists and classify them as "agonist lock touched" and "agonist lock untouched" RORγt inverse agonists according to whether they infringe on the agonist lock directly or not. We aim at providing a comprehensive review and insights into drug discovery of RORγt inverse agonists.

Retinoic acid-related orphan receptor gamma t (RORγt) inverse agonists/antagonists for the treatment of inflammatory diseases - where are we presently?

Introduction: The transcription factor retinoic acid-related orphan receptor gamma t (RORγt) has been identified as the master regulator of T_H17 cell differentiation and IL-17/22 production and is therefore an attractive target for the treatment of inflammatory diseases. Several orally or topically administered small molecule RORγt inverse agonists (RIAs) have progressed up to the end of clinical Phase 2.Areas covered: Based on publications and patent evaluations this review summarizes the evolution of the chemical matter for all 16 pharmaceutical companies, who develop(ed) a clinical-stage RIAs (until March 2021). Structure proposals for some clinical stage RIAs are presented and the outcome of the clinical trials is discussed.Expert opinion: So far, the clinical trials have been plagued with a high attrition rate. Main reasons were lack of efficacy (topical) or safety signals (oral) as well as, amongst other things, thymic lymphomas as seen with BMS-986251 in a preclinical study and liver enzyme elevations in humans with VTP-43742. Possibilities to mitigate these risks could be the use of RIAs with different chemical structures not interfering with thymocytes maturation and no livertox-inducing properties. With new frontrunners (e.g., ABBV-157 (cedirogant), BI 730357 or IMU-935) this is still an exciting time for this treatment approach.

Circadian clock genes as promising therapeutic targets for autoimmune diseases

Circadian rhythm is a natural, endogenous process whose physiological functions are controlled by a set of clock genes. Disturbance of the clock genes have detrimental effects on both innate and adaptive immunity, which significantly enhance pro-inflammatory responses and susceptibility to autoimmune diseases via strictly controlling the individual cellular components of the immune system that initiate and perpetuate the inflammation pathways. Autoimmune diseases, especially rheumatoid arthritis (RA), often exhibit substantial circadian oscillations, and circadian rhythm is involved in the onset and progression of autoimmune diseases. Mounting evidence indicate that the synthetic ligands of circadian clock genes have the property of reducing the susceptibility and clinical severity of subjects. This review supplies an overview of the roles of circadian clock genes in the pathology of autoimmune diseases, including BMAL1, CLOCK, PER, CRY, REV-ERBα, and ROR. Furthermore, summarized some circadian clock genes as candidate genes for autoimmune diseases and current advancement on therapy of autoimmune diseases with synthetic ligands of circadian clock genes. The existing body of knowledge demonstrates that circadian clock genes are inextricably linked to autoimmune diseases. Future research should pay attention to improve the quality of life of patients with autoimmune diseases and reduce the effects of drug preparation on the normal circadian rhythms.

Asymmetric Synthesis of a 5,6,7,8-Tetrahydro-1,6-naphthyridine Scaffold Leading to Potent Retinoid-Related Orphan Receptor γt Inverse Agonist TAK-828F

An asymmetric synthesis of the tetrahydronaphthyridine scaffold of TAK-828F as a RORγt inverse agonist has been developed. The synthesis features a newly discovered atom-economical protocol for Heck-type vinylation of chloropyridine using ethylene gas, an unprecedented formation of dihydronaphthyridine directly from 2-vinyl-3-acylpyridine mediated by ammonia, and a ruthenium-catalyzed enantioselective transfer hydrogenation as key steps. This represents the first example of the enantioselective synthesis of a 5,6,7,8-tetrahydro-1,6-naphthyridine compound. The new synthesis is also free of chromatography or distillation purification processes and therefore qualifies for extension to large-scale manufacture.

Transcriptional Regulators of T Helper 17 Cell Differentiation in Health and Autoimmune Diseases

T helper (Th) 17 cells are a subtype of CD4 T lymphocytes characterized by the expression of retinoic acid-receptor (RAR)-related orphan receptor (ROR)γt transcription factor, encoded by gene Rorc. These cells are implicated in the pathology of autoimmune inflammatory disorders as well as in the clearance of extracellular infections. The main function of Th17 cells is the production of cytokine called interleukin (IL)-17A. This review highlights recent advances in mechanisms regulating transcription of IL-17A. In particular, we described the lineage defining transcription factor RORγt and other factors that regulate transcription of Il17a or Rorc by interacting with RORγt or by binding their specific DNA regions, which may positively or negatively influence their expression. Moreover, we reported the eventual involvement of those factors in Th17-related diseases, such as multiple sclerosis, rheumatoid arthritis, psoriasis, and Crohn's disease, characterized by an exaggerated Th17 response. Finally, we discussed the potential new therapeutic approaches for Th17-related diseases targeting these transcription factors. The wide knowledge of transcriptional regulators of Th17 cells is crucial for the better understanding of the pathogenic role of these cells and for development of therapeutic strategies aimed at fighting Th17-related diseases.

Discovery of N-(Indazol-3-yl)piperidine-4-carboxylic Acids as RORγt Allosteric Inhibitors for Autoimmune Diseases

The clinical success of anti-IL-17 monoclonal antibodies (i.e., Cosentyx and Taltz) has validated Th17 pathway modulation for the treatment of autoimmune diseases. The nuclear hormone receptor RORγt is a master regulator of Th17 cells and affects the production of a host of cytokines, including IL-17A, IL-17F, IL-22, IL-26, and GM-CSF. Substantial interest has been spurred across both academia and industry to seek small molecules suitable for RORγt inhibition. A variety of RORγt inhibitors have been reported in the past few years, the majority of which are orthosteric binders. Here we disclose the discovery and optimization of a class of inhibitors, which bind differently to an allosteric binding pocket. Starting from a weakly active hit 1, a tool compound 14 was quickly identified that demonstrated superior potency, selectivity, and off-target profile. Further optimization focused on improving metabolic stability. Replacing the benzoic acid moiety with piperidinyl carboxylate, modifying the 4-aza-indazole core in 14 to 4-F-indazole, and incorporating a key hydroxyl group led to the discovery of 25, which possesses exquisite potency and selectivity, as well as an improved pharmacokinetic profile suitable for oral dosing.

Gut Microbiota Modulation on Intestinal Mucosal Adaptive Immunity

The mammalian intestine harbors a remarkable number of microbes and their components and metabolites, which are fundamental for the instigation and development of the host immune system. The intestinal innate and adaptive immunity coordinate and interact with the symbionts contributing to the intestinal homeostasis through establishment of a mutually beneficial relationship by tolerating to symbiotic microbiota and retaining the ability to exert proinflammatory response towards invasive pathogens. Imbalance between the intestinal immune system and commensal organisms disrupts the intestinal microbiological homeostasis, leading to microbiota dysbiosis, compromised integrity of the intestinal barrier, and proinflammatory immune responses towards symbionts. This, in turn, exacerbates the degree of the imbalance. Intestinal adaptive immunity plays a critical role in maintaining immune tolerance towards symbionts and the integrity of intestinal barrier, while the innate immune system regulates the adaptive immune responses to intestinal commensal bacteria. In this review, we will summarize recent findings on the effects and mechanisms of gut microbiota on intestinal adaptive immunity and the plasticity of several immune cells under diverse microenvironmental settings.

VPR-254: an inhibitor of ROR-gamma T with potential utility for the treatment of inflammatory bowel disease

INTRODUCTION

Retinoic Acid Related Orphan Nuclear Receptor gamma T (RORγT) is a lineage specifying transcription factor for IL-17 expressing cells, which may contribute to the pathogenesis of Inflammatory Bowel Disease (IBD). VPR-254 is a selective in vitro inhibitor of RORγT.

AIMS

The main goals of our study were twofold: (1) To determine if ex vivo treatment with VPR-254 reduced relevant cytokine (IL-17 and IL-21) secretion from colonic strips of mice with colitis; (2) To determine if treatment of mice with VPR-254 attenuated parameters of colitis, using three murine IBD models.

METHODS

VPR-254 was evaluated ex vivo in a colonic strip assay, using tissue from mice with Dextran sulfate sodium (DSS)-induced colitis. In vivo, VPR-254 was evaluated for efficacy in DSS, Trintirobenzenesulfonic acid (TNBS) and Anti-CD40 antibody-induced murine models of colitis.

RESULTS

VPR-254 reduced the production of key pro-inflammatory cytokines (e.g., IL-17) in ex vivo and in vivo models of colitis. This small molecule inhibitor of RORγT also improved various morphometric and histological parameters associated with three diverse murine models of IBD.

CONCLUSION

Our results support the concept that an inhibitor of ROR-gamma T may have potential utility for the treatment of IBD.

IL-12, IL-23 and IL-17 in IBD: immunobiology and therapeutic targeting

IL-12 and IL-23 are closely related cytokines with important roles in the regulation of tissue inflammation. Converging evidence from studies in mice, human observational studies and population genetics supports the importance of these cytokines in the regulation of mucosal inflammation in the gut in particular. Ustekinumab, a therapeutic antibody targeting both cytokines is now widely licensed for the treatment of Crohn's disease, including in Europe, the USA, Canada and Japan, whilst agents targeting IL-23 specifically are in late-phase clinical trials. We review the emerging understanding of the biology of IL-12 and IL-23, as well as that of their major downstream cytokines, including IL-17. In particular, we discuss how their biology has influenced the development of clinical trials and therapeutic strategies in IBD, as well as how findings from clinical trials, at times surprising, have in turn refocused our understanding of the underlying biology.

Vitamin A and inflammatory bowel diseases: from cellular studies and animal models to human disease

Vitamin A (VA) and metabolites such as Retinoic Acid (RA) and all-trans-RA (at-RA) are crucial in the modulation of the immune system and may be determinative in the balance of the immune responses. Inflammatory bowel diseases (IBD) consist of chronic relapsing and heterogeneous disorders with not well-known etiology. Due to its role in inflammatory processes, VA may be helpful in the treatment of IBD. Area covered: As VA plays a significant role in the inflammatory processes, this review aims to show the potential role of this vitamin in IBD, searching for cellular studies, animal models, and studies with humans. Expert commentary: Many studies have described the importance of alternative therapeutic approaches for IBD. Due to its role in the immune system, VA may also exert an indispensable role in the IBD. Nevertheless, some authors have shown that these compounds could stimulate the release of pro-inflammatory cytokines. For these reasons, more studies should be performed to establish the precise mechanisms of VA and its metabolites in systemic and intestinal inflammation.

A role for Th1-like Th17 cells in the pathogenesis of inflammatory and autoimmune disorders

The T helper 17 (Th17) cells contain a dynamic subset of CD4+ T-cells that are able to develop into other different lineage subsets, including the Th1-like Th17 cells. These cells co-express retinoic acid-related orphan receptor gamma t (RORγt) and transcription factor T-box-expressed-in-T-cells (T-bet) and produce both interleukin (IL)-17 and interferon (IFN)-γ. Recent reports have shown that Th1-like Th17 cells play crucial roles in the pathogenesis of autoimmune diseases such as inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, as well as, some primary immunodeficiency with autoimmune features. Here, the actual mechanisms for Th17 cells plasticity to Th1-like Th17 cells are discussed and reviewed in association to the role that Th1-like Th17 cells have on inflammatory and autoimmune disorders.

Cholesterol Unbound RORγt Protein Enables a Sensitive Inverse Agonist Screening

The retinoic acid-related orphan receptor gamma T (RORγt) plays an important role in Th17 cell proliferation and functionality. Thus, RORγt inverse agonists are thought to be potent therapeutic agents for Th17-mediated autoimmune diseases, such as rheumatoid arthritis, asthma, inflammatory bowel disease, and psoriasis. Although RORγt has constitutive activity, it is recognized that the receptor is physiologically regulated by various cholesterol derivatives. In this study, we sought to identify RORγt inverse agonists through a high-throughput screening campaign. To this end, we compared an apo-RORγt protein from Escherichia coli and a cholesterol-bound RORγt protein from insect cells. The IC₅₀ of the known RORγt inverse agonist TO901317 was significantly lower for the apoprotein than for the cholesterol-bound RORγt. Through high-throughput screening using a fluorescence-based cholesterol binding assay with the apoprotein, we identified compound 1 as a novel cholesterol-competitive RORγt inverse agonist. Compound 1 inhibited the RORγt-TopFluor cholesterol interaction, coactivator recruitment, and transcriptional activity of RORγt. Cell-based reporter gene assay demonstrated that compound 1 showed higher potency by lipid depletion treatment. Collectively, our findings indicate that eliminating cholesterol from the RORγt protein is suitable for sensitive high-throughput screening to identify RORγt inverse agonists.

Transcription Factor Retinoid-Related Orphan Receptor γt: A Promising Target for the Treatment of Psoriasis

Psoriasis, which is a common chronic inflammatory skin disease, endangers human health and brings about a major economic burden worldwide. To date, treatments for psoriasis remain unsatisfied because of their clinical limitations and various side effects. Thus, developing a safer and more effective therapy for psoriasis is compelling. Previous studies have explicitly shown that psoriasis is an autoimmune disease that is predominantly mediated by T helper 17 (Th17) cells, which express high levels of interleukin-17 (IL-17) in response to interleukin-23 (IL-23). The discovery of the IL-23–Th17–IL-17 axis in the development of psoriasis has led to the paradigm shift of understanding pathogenesis of psoriasis. Although anti-IL-17 antibodies show marked clinical efficacy in treating psoriasis, compared with antibodies targeting IL-17A or IL-17R alone, targeting Th17 cells themselves may have a maximal benefit by affecting multiple proinflammatory cytokines, including IL-17A, IL-17F, IL-22, and granulocyte-macrophage colony-stimulating factor, which likely act synergistically to drive skin inflammation in psoriasis. In this review, we mainly focus on the critical role of Th17 cells in the pathogenesis of psoriasis. Especially, we explore the small molecules that target retinoid-related orphan receptor γt (RORγt), a vital transcription factor for Th17 cells. Given that RORγt is the lineage-defining transcription factor for Th17 cell differentiation, targeting RORγt via small molecular inverse agonists may be a promising strategy for the treatment of Th17-mediated psoriasis.