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RORγt is an isoform of RORC, preferentially expressed in Th17 cells, that functions as a critical regulator of type 3 immunity. As murine Th17-driven inflammatory disease models were greatly diminished in RORC knock-out mice, this receptor was prioritised as an attractive therapeutic target for the treatment of several autoimmune diseases. Human genetic studies indicate a significant contributory role for RORC in several human disease conditions. Furthermore, genome-wide association studies (GWAS) report a significant association between inflammatory bowel disease (IBD) and the RORC regulatory variant rs4845604. To investigate if the rs4845604 variant may affect CD4+ T cell differentiation events, naïve CD4+ T cells were isolated from eighteen healthy subjects homozygous for the rs4845604 minor (A) or major (G) allele). Isolated cells from each subject were differentiated into distinct T cell lineages by culturing in either T cell maintenance medium or Th17 driving medium conditions for six days in the presence of an RORC inverse agonist (to prevent constitutive receptor activity) or an inactive diastereomer (control). Our proof of concept study indicated that genotype had no significant effect on the mean number of naïve CD4 T cells isolated, nor the frequency of Th1-like and Th17-like cells following six days of culture in any of the four culture conditions. Analysis of the derived RNA-seq count data identified genotype-driven transcriptional effects in each of the four culture conditions. Subsequent pathway enrichment analysis of these profiles reported perturbation of metabolic signalling networks, with the potential to affect the cellular detoxification response. This investigation reveals that rs4845604 genotype is associated with transcriptional effects in CD4+ T cells that may perturb immune and metabolic pathways. Most significantly, the rs4845604 GG, IBD risk associated, genotype may be associated with a differential detoxification response. This observation justifies further investigation in a larger cohort of both healthy and IBD-affected individuals.

Biaryl amides as new RORγt modulators were discovered. The crystal structure of biaryl amide agonist 6 in complex with RORγt ligand binding domain (LBD) was resolved, and both “short” and “long” inverse agonists were obtained by removing from 6 or adding to 6 a proper structural moiety. While “short” inverse agonist (8) recruits a corepressor peptide and dispels a coactivator peptide, “long” inverse agonist (9) dispels both. The two types of inverse agonists can be utilized as potential tools to study mechanisms of Th17 transcriptional network inhibition and related disease biology.

Gut microbes make T cells keep the peace Our guts harbor trillions of microbial inhabitants, some of which regulate the types of immune cells that are present in the gut. For instance, Clostridium species of bacteria induce a type of T cell that promotes tolerance between the host and its microbial contents. Ohnmacht et al. and Sefik et al. characterized a population of gut regulatory T cells in mice, which required gut microbiota to survive. Multiple bacterial species of the microbiota could induce transcription factor–expressing regulatory T cells that helped maintain immune homeostasis. Mice engineered to lack these transcription factors exhibited enhanced susceptibility to colonic inflammation and had elevated amounts of proinflammatory molecules associated with allergies (see the Perspective by Hegazy and Powrie). Science , this issue pp. 989 and 993

Chronic graft-versus-host disease (cGvHD) remains a major complication of allogeneic stem cell transplantation requiring novel therapies. CD146 and CCR5 are expressed by activated T cells and associated with increased T cell migration capacity and Th17 polarization. We performed a multiparametric flow cytometry analysis in a cohort of 40 HSCT patients together with a cGvHD murine model to understand the role of CD146-expressing subsets. We observed an increased frequency of CD146+ CD4 T cells in the 20 patients with active cGvHD with enhanced RORγt expression. This Th17-prone subset was enriched for cells coexpressing CD146 and CCR5 that harbor mixed Th1/Th17 features and were more frequent in cGvHD patients. Utilizing a murine cGvHD model with bronchiolitis obliterans (BO), we observed that donor T cells from CD146-deficient mice versus those from WT mice caused significantly reduced pulmonary cGvHD. Reduced cGvHD was not the result of failed germinal center B cell or T follicular helper cell generation. Instead, CD146-deficient T cells had significantly lower pulmonary macrophage infiltration and T cell CCR5, IL-17, and IFN-γ coexpression, suggesting defective pulmonary end-organ effector mechanisms. We, thus, evaluated the effect of TMP778, a small-molecule RORγt activity inhibitor. TMP778 markedly alleviated cGvHD in murine models similarly to agents targeting the Th17 pathway, such as STAT3 inhibitor or IL-17–blocking antibody. Our data suggest CD146-expressing T cells as a cGvHD biomarker and suggest that targeting the Th17 pathway may represent a promising therapy for cGvHD.

Experimental autoimmune uveitis (EAU), an animal model for severe intraocular inflammatory eye diseases, is mediated by both Th1 and Th17 cells. Here, we examined the capacity of TMP778, a selective inhibitor of RORγt, to inhibit the development of EAU, as well as the related immune responses. EAU was induced in B10.A mice by immunization with interphotoreceptor retinoid-binding protein (IRBP). Treatment with TMP778 significantly inhibited the development of EAU, determined by histological examination. In addition, the treatment suppressed the cellular immune response to IRBP, determined by reduced production of IL-17 and IFN-γ, as well as lower percentages of lymphocytes expressing these cytokines, as compared to vehicle-treated controls. The inhibition of IFN-γ expression by TMP778 is unexpected in view of this compound being a selective inhibitor of RORγt. The observation was further confirmed by the finding of reduced expression of the T-bet (Tbx21) gene, the transcription factor for IFN-γ, by cells of TMP778-treated mice. Thus, these data demonstrate the capacity of TMP778 to inhibit pathogenic autoimmunity in the eye and shed new light on its mode of action in vivo.

IL-17–producing CD4+Th17 cells, CD8+Tc17 cells, and γδ T cells play critical roles in the pathogenesis of autoimmune psoriasis. RORγt is required for the differentiation of Th17 cells and expression of IL-17. In this article, we describe a novel, potent, and selective RORγt inverse agonist (TMP778), and its inactive diastereomer (TMP776). This chemistry, for the first time to our knowledge, provides a unique and powerful set of tools to probe RORγt-dependent functions. TMP778, but not TMP776, blocked human Th17 and Tc17 cell differentiation and also acutely modulated IL-17A production and inflammatory Th17-signature gene expression (Il17a, Il17f, Il22, Il26, Ccr6, and Il23) in mature human Th17 effector/memory T cells. In addition, TMP778, but not TMP776, inhibited IL-17A production in both human and mouse γδ T cells. IL-23–induced IL-17A production was also blocked by TMP778 treatment. In vivo targeting of RORγt in mice via TMP778 administration reduced imiquimod-induced psoriasis-like cutaneous inflammation. Further, TMP778 selectively regulated Th17-signature gene expression in mononuclear cells isolated from both the blood and affected skin of psoriasis patients. In summary, to our knowledge, we are the first to demonstrate that RORγt inverse agonists: 1) inhibit Tc17 cell differentiation, as well as IL-17 production by γδ T cells and CD8+ Tc17 cells; 2) block imiquimod-induced cutaneous inflammation; 3) inhibit Th17 signature gene expression by cells isolated from psoriatic patient samples; and 4) block IL-23–induced IL-17A expression. Thus, RORγt is a tractable drug target for the treatment of cutaneous inflammatory disorders, which may afford additional therapeutic benefit over existing modalities that target only IL-17A.

Although the main focus of immuno-oncology has been manipulating the adaptive immune system, harnessing both the innate and adaptive arms of the immune system might produce superior tumour reduction and elimination. Tumour-associated macrophages often have net pro-tumour effects, but their embedded location and their untapped potential provide impetus to discover strategies to turn them against tumours. Strategies that deplete (anti-CSF-1 antibodies and CSF-1R inhibition) or stimulate (agonistic anti-CD40 or inhibitory anti-CD47 antibodies) tumour-associated macrophages have had some success. We hypothesized that pharmacologic modulation of macrophage phenotype could produce an anti-tumour effect. We previously reported that a first-in-class selective class IIa histone deacetylase (HDAC) inhibitor, TMP195, influenced human monocyte responses to the colony-stimulating factors CSF-1 and CSF-2 in vitro. Here, we utilize a macrophage-dependent autochthonous mouse model of breast cancer to demonstrate that in vivo TMP195 treatment alters the tumour microenvironment and reduces tumour burden and pulmonary metastases by modulating macrophage phenotypes. TMP195 induces the recruitment and differentiation of highly phagocytic and stimulatory macrophages within tumours. Furthermore, combining TMP195 with chemotherapy regimens or T-cell checkpoint blockade in this model significantly enhances the durability of tumour reduction. These data introduce class IIa HDAC inhibition as a means to harness the anti-tumour potential of macrophages to enhance cancer therapy.

We have discovered novel benzofuran-based S1P1 agonists with excellent in vitro potency and selectivity. 1-((4-(5-Benzylbenzofuran-2-yl)-3-fluorophenyl)methyl) azetidine-3-carboxylic acid (18) is a potent S1P1 agonist with >1000× selectivity over S1P3. It demonstrated a good in vitro ADME profile and excellent oral bioavailability across species. Dosed orally at 0.3 mg/kg, 18 significantly reduced blood lymphocyte counts 24 h postdose and demonstrated efficacy in a mouse EAE model of relapsing MS.

EtAlCl(2)-induced cyclization of chiral gamma,delta-unsaturated ketones 11c and 17b takes place mainly from the expected face. The selectivity is modest for 11c (60:40) in which the large substituent is a primary alkyl group and the medium substituent is a methyl group and excellent for 17b (93:7) in which the large substituent is a cyclohexyl group and the medium substituent is a methyl group. The cyclization of 17a is anomalous, suggesting that the phenyl group has more than a simple steric effect.

The orphan nuclear receptor, retinoic acid receptor-related orphan nuclear receptor γt (RORγt), is required for the development and pathogenic function of interleukin-17A-secreting CD4(+) T helper type 17 (Th17) cells. Whereas small molecule RORγt antagonists impair Th17 cell development and attenuate autoimmune inflammation in vivo, the broader effects of these inhibitors on RORγt-dependent gene expression in vivo has yet to be characterized. We show that the RORγt inverse agonist TMP778 acts potently and selectively to block mouse Th17 cell differentiation in vitro and to impair Th17 cell development in vivo upon immunization with the myelin antigen MOG35-55 plus complete Freund's adjuvant. Importantly, we show that TMP778 acts in vivo to repress the expression of more than 150 genes, most of which fall outside the canonical Th17 transcriptional signature and are linked to a variety of inflammatory pathologies in humans. Interestingly, more than 30 genes are related with SMAD3, a transcription factor involved in the Th17 cell differentiation. These results reveal novel disease-associated genes regulated by RORγt during inflammation in vivo, and provide an early read on potential disease indications and safety concerns associated with pharmacological targeting of RORγt.

We identified three retinoid-related orphan receptor gamma t (RORγt)-specific inhibitors that suppress T helper 17 (Th17) cell responses, including Th17-cell-mediated autoimmune disease. We systemically characterized RORγt binding in the presence and absence of drugs with corresponding whole-genome transcriptome sequencing. RORγt acts as a direct activator of Th17 cell signature genes and a direct repressor of signature genes from other T cell lineages; its strongest transcriptional effects are on cis-regulatory sites containing the RORα binding motif. RORγt is central in a densely interconnected regulatory network that shapes the balance of T cell differentiation. Here, the three inhibitors modulated the RORγt-dependent transcriptional network to varying extents and through distinct mechanisms. Whereas one inhibitor displaced RORγt from its target loci, the other two inhibitors affected transcription predominantly without removing DNA binding. Our work illustrates the power of a system-scale analysis of transcriptional regulation to characterize potential therapeutic compounds that inhibit pathogenic Th17 cells and suppress autoimmunity., United States. National Institutes of Health (DP1OD003958-01)

Publisher Summary This chapter focuses on the Th17 and T regulatory (Treg) signaling pathways in autoimmunity. Treg cells are distinguished from conventional naive T cells by their constitutive expression of the transcription factor Forkhead box, winged-helix protein 3 (Foxp3). Current paradigms suggest that the balance between conventional naive T cell activation and Treg-mediated immune suppression controls whether immune responses are ultimately protective, ineffective, or pathogenic. Early clinical results utilizing Treg cellular therapy support the notion that increasing Treg numbers in autoimmune patients can support tolerance. Evidence from both autoimmune mouse models and human patients reveals that Treg cells are necessary to prevent spontaneous autoimmunity throughout life, thereby indicating that Treg cells can also regulate immune responses to pathogens and developing tumors. T cell–driven autoimmune disorders continue to present a significant unmet clinical need. Advances in the understanding of T cell activation, differentiation, and regulation have yielded novel approaches to specifically dampen pathogenic immune reactions without creating potentially dangerous states of general immune suppression. Specific modulation of Th17 and Treg cells affords broad therapeutic promise for the treatment of autoimmune and chronic inflammatory conditions.

Optimization of a benzofuranyl S1P1 agonist lead compound (3) led to the discovery of 1-(3-fluoro-4-(5-(2-fluorobenzyl)benzo[d]thiazol-2-yl)benzyl)azetidine-3-carboxylic acid (14), a potent S1P1 agonist with minimal activity at S1P3. Dosed orally at 0.3 mg/kg, 14 significantly reduced blood lymphocyte counts 24 h postdose and attenuated a delayed type hypersensitivity (DTH) response to antigen challenge.

HCl-catalyzed deprotection and cyclization of benzylic alcohol 15 cleanly provided tricycle 16 by a cis-selective intramolecular Diels–Alder reaction. Acetylation of the phenol, bis epoxidation, and base-catalyzed hydrolysis and cyclization afforded tetracycle 19 with the bisabosqual skeleton, but the opposite stereochemistry at the tertiary alcohol stereocenter. Selective dehydration of the tertiary alcohol to form the exocyclic alkene, ozonolysis, reductive deoxygenation of the side chain epoxide, and addition of MeMgBr to the ketone from the less hindered face gave tertiary alcohol 24 with the tetracyclic core of bisabosqual A (1).

We have developed two practical one-step syntheses of 2,3-dihydro-3-hydroxy-2-hydroxyalkylbenzofurans from readily available optically pure alpha,beta-epoxy aldehydes. Electron-deficient resorcinols react with epoxy aldehydes using either Cs2CO3 in DMF or KOH/CaCl2 in MeOH to give adducts 13, 16, 18, 20, 21, and brosimacutin G (6t). Grignard reagents prepared by low-temperature halogen-metal exchange of acetoxy iodocoumarins 35d and 40 and acetoxy bromonaphthalene 41 add to epoxy aldehyde (S)-26 to complete the first syntheses of vaginidiol (7c), vaginol (7t), smyrindiol (8c), xanthoarnol (8t), and avicenol A (9t). Acid-catalyzed fragmentation of vaginidiol or vaginol provides angelicin, while that of smyrindiol or xanthoarnol affords psoralen. In both cases, the trans isomers fragment only twice as fast as the cis isomers, possibly through the intermediacy of a common benzylic cation. This may have implications for the biosynthesis of angelicin and psoralen.

HCl-catalyzed deprotection and cyclization of 8b provided tricycle 9b cleanly. Epoxidation of 9b afforded tetracycle 13 with the wrong stereochemistry at the tertiary alcohol. Selective elimination of the tertiary alcohol to give the exocyclic methylene compound, alkene cleavage to form the ketone with OsO 4 and NaIO 4 , and addition of MeMgBr to the ketone from the least hindered face gave tertiary alcohol 16 with the tetracyclic core of bisabosqual A ( 1 ).

EtAlCl2-induced cyclization of chiral γ,δ-unsaturated ketones 11c and 17b takes place mainly from the expected face. The selectivity is modest for 11c (60:40) in which the large substituent is a pr...

Improved syntheses of the naturally occurring sulfonium ion, salacinol are described. Salacinol is one of the active principles in the aqueous extracts of Salacia reticulata that are traditionally used in Sri Lanka and India for the treatment of Type 2 Diabetes. The synthetic strategy relies on the nucleophilic attack of 2,3,5-tri-O-benzyl- or 2,3,5-tri-O-p-methoxybenzyl- 1 ,4-anhydro-4-thio-D-arabinitol at the least hindered carbon of benzylidene-protected L-erythritol-1,3-cyclic sulfate in 1,1,1,3,3,3-hexafluoro-2-propanol as solvent. The reactions are compared to those with the benzyl-protected L-erythritol-1.3-cyclic sulfate and also to those in acetone and 2-propanol. Excellent yields are obtained for the reactions with the benzylidene-protected cyclic sulfate. The synthetic route employing p-methoxybenzyl ether protecting groups is advantageous since all protecting groups in the adduct may be removed with trifluoroacetic acid to yield salacinol, thereby obviating the problematic deprotection of benzyl ethers by hydrogenolysis.

IL-17-producing Th17 cells, Tc17 cells and γδ T cells play critical roles in the pathogenesis of autoimmune psoriasis. RORγt is required for the differentiation of Th17 cells and expression of IL-17. Here we describe a novel, potent, and selective RORγt inverse agonist (TMP778), and its inactive diastereomer (TMP776). This chemistry, for the first time, provides a unique and powerful set of tools to probe RORγt-dependent functions. TMP778, but not TMP776, blocked human Th17 and Tc17 cell differentiation and also acutely modulated Th17-signature gene expression. In addition, TMP778 but not TMP776 inhibited IL-17 production in both human and mouse γδ T cells. IL-23-induced IL-17 production was also blocked by TMP778 treatment. In vivo targeting of RORγt in mice via TMP778 administration reduced imiquimod-induced psoriasis-like cutaneous inflammation. Further, TMP778 selectively regulated Th17-signature gene expression in mononuclear cells isolated from both the blood and affected skin of psoriasis patients. In summary, we are the first to demonstrate that RORγt inverse agonists (1) inhibit Tc17 cell differentiation, as well as IL-17 production by γδ T cells and CD8+ Tc17 cells; (2) block imiquimod-induced cutaneous inflammation; (3) inhibit Th17 signature gene expression by cells isolated from psoriatic patient samples; and (4) block IL-23-induced IL-17A expression. Thus, RORγt is a tractable drug target for the treatment of cutaneous inflammatory disorders.