Background The human enthesis conventional T cells are poorly characterised. Objectives To study the biology of the conventional T cells in human enthesis. Methods CD4+ and CD8+ T cells were investigated in 25 enthesis samples using immunofluorescence, cytometrically, bulk RNAseq and quantitative real-time PCR following anti-CD3/CD28 bead stimulation to determine interleukin (IL)-17A and tumour necrosis factor (TNF) levels. T-cell receptor (TCR) repertoires were characterised and a search for putative T-cell reactivity was carried out using TCR3 database. The impact of pharmacological antagonism with retinoic acid receptor-related orphan nuclear receptor gamma t inhibitor (ROR 3ti), methotrexate and phosphodiesterase type 4 inhibitor (PDE4i) was investigated. Results Immunofluorescence and cytometry suggested entheseal resident CD4+ and CD8+ T cells with a resident memory phenotype (CD69+/CD45RA-) and tissue residency gene transcripts (higher NR4A1/AhR and lower KLF2/T-bet transcripts). Both CD4+ and CD8+ T cells showed increased expression of immunomodulatory genes including IL-10 and TGF-β compared with peripheral blood T cells with entheseal CD8+ T cells having higher CD103, CD49a and lower SIPR1 transcript that matched CD4+ T cells. Following stimulation, CD4+ T cells produced more TNF than CD8+ T cells and IL-17A was produced exclusively by CD4+ T cells. RNAseq suggested both Cytomegalovirus and influenza A virus entheseal resident T-cell clonotype reactivity. TNF and IL-17A production from CD4+ T cells was effectively inhibited by PDE4i, while ROR 3ti only reduced IL-17A secretion. Conclusions Healthy human entheseal CD4+ and CD8+ T cells exhibit regulatory characteristics and are predicted to exhibit antiviral reactivity with CD8+ T cells expressing higher levels of transcripts suggestive of tissue residency. Inducible IL-17A and TNF production can be robustly inhibited in vitro.

https://ard.bmj.com/content/annrheumdis/79/8/1044.full.pdf

Normal human enthesis harbours conventional CD4+ and CD8+ T cells with regulatory features and inducible IL-17A and TNF expression

Retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt or RORc2) is a key transcription factor for the differentiation of naive proinflammatory CD4+ T cells and the production of T helper-17 (TH17) cells. Inhibiting RORγt activity is thought to be beneficial in targeting a variety of inflammatory and autoimmune disorders. Recently Vitae Pharmaceuticals (to be acquired by Allergan) reported positive top-line results from a Phase 2a clinical trial of RORγt inhibitor VTP-43742 in psoriatic patients. The compound was reported to demonstrate a clear signal of efficacy over a short four-week period and no drug-related cardiac abnormalities were observed; however, in the 700 mg dose group reversible transaminase elevations were observed in four patients, which prompted the company to cancel testing VTP-43742 at a initially planned third, higher dose. In Vitae Pharmaceuticals latest patent applications, WO2016061160 and US20160122345, potential dihydropyrrolopyridine back-up compounds of cl...

RORγt inhibitors as potential back-ups for the phase II candidate VTP-43742 from Vitae Pharmaceuticals: patent evaluation of WO2016061160 and US20160122345

Retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt or RORC2) is a key transcription factor for the differentiation of naive proinflammatory CD4(+) T cells and the production of T helper-17 (TH17) cells. Inhibiting RORγt activity is thought to be beneficial in targeting a variety of inflammatory and autoimmune disorders, however current candidates remain to be validated in the clinic. Recently Vitae Pharmaceuticals successfully finished its Phase 1 single ascending dose clinical study with their proprietary RORγt inverse agonist VTP-43742. On the basis of the reported promising results, Vitae Pharmaceuticals could currently be considered as having the leading clinical candidate in the RORγt inverse agonist category. This prompts the interest on the exact chemical structure of their clinical candidate. The first relevant patent application (WO2014179564) from Vitae Pharmaceuticals describes RORγt inverse agonists with a 5,6-dihydro-4H-pyrrolo[3,4-d]thiazole core, while in the second and latest patent application (WO2015116904) this element has changed towards a 6,7-dihydro-5H-pyrrolo[3,4-b]pyridine core. By combining information from Vitae's patent applications and trustworthy online information, the potential elucidation of the chemical structure of clinical candidate VTP-43742 is described.

Retinoid-related orphan receptor gamma t (RORγt) inhibitors from Vitae Pharmaceuticals (WO2015116904) and structure proposal for their Phase I candidate VTP-43742

Retinoic-acid-related orphan receptor γt (RORγt) inverse agonists could be used for the treatment of autoimmune diseases. Previously, we reported a novel quinazolinedione 1 a with a flexible linear linker as a novel RORγt inverse agonist. A U-shaped conformation in the complex structure of 1 a with RORγt protein was confirmed. Further improvement of the pharmacokinetic (PK) profiles was required because of the low drug exposure in mice upon oral administration (mouse AUC of 1 a: 27 ng ⋅ h ⋅ mL-1 at 1 mg ⋅ kg-1 , p.o.). To improve the PK profiles, conformationally constrained U-shaped scaffolds were investigated. As a result, morpholine analogues with improved PK profiles and high potency were successfully identified. The substituent at the N1 position of the quinazoline moiety was also modified, leading to an enhancement of reporter activity. Consequently, compound 43 (N2 -(3-chloro-4-cyanophenyl)-N4 -(3-(cyclopropylmethyl)-1-isopropyl-2,4-dioxo-1,2,3,4-tetrahydroquinazolin-6-yl)morpholine-2,4-dicarboxamide) exhibited improved drug exposure (mouse AUC: 1289 ng ⋅ h ⋅ mL-1 at 1 mg ⋅ kg-1 , p.o.). In addition, suppression of IL-17A gene expression by IL-23 stimulation in a mouse pharmacodynamics model was observed for 43. The conformation of 43 with RORγt protein was also confirmed as U-shape by X-ray co-crystal structure analysis. The key interaction that boosts potency is also discussed.

Design and Synthesis of Conformationally Constrained RORγt Inverse Agonists

Psoriasis is a chronic inflammatory skin disorder. The prevalence of psoriasis is estimated at approximately 100 million people worldwide. In mild-to-moderate, as well as moderate-to-severe, psoriasis, 70–80% of patients start with topical agents and continue to use them with other active therapies. This group of patients can benefit from topical treatment with minimal systemic exposure. The expression levels of IL-23 and IL-17 are upregulated in psoriatic skin compared with non-lesional skin, associated with psoriasis pathogenesis. The skin epidermal proliferation and psoriasis are caused by overactive Th17 cells, which are promoted and stabilized by the activated IL-23 receptor, forming part of the positive feedback loop. FDA approved biologics in IL-23/IL-17 axis (ustekinumab, guselkumab, risankizumab, tildrakizumab, ixekizumab, secukinumab and brodalumab) demonstrated superior clinical efficacy in the systemic treatment of moderate-to-severe psoriasis, providing the clinical proof of concept of the IL-23/IL-17 axis as a major immune pathway underlying the pathophysiology of psoriasis. However, due to the large size and poor permeability into skin, biologics are not suitable to deliver via topical route. Current topical treatments of mild-to-moderate psoriasis are corticosteroids and vitamin D analogues, which have limited efficacy with significant side effects so that patients must avoid long-term use. This chapter reviews current molecular targeted therapeutics under development for topical treatment of psoriasis. 

/pdf/developing-novel-molecular-targeted-therapeutics-for-topical-1rr78o5r.pdf

Developing Novel Molecular Targeted Therapeutics for Topical Treatment of Psoriasis

Increased production of the inflammatory cytokine IL-17A by Th17 cells is a driver of multiple autoimmune disorders, including psoriasis, ankylosing spondylitis (AS) and psoriatic arthritis (PsA). The nuclear receptor RORγt, IL-23 and TGFb are required for the differentiation of Th17 cells. RORγt stabilizes the Th17 phenotype by increasing the expression of IL-23R and inducing the synthesis of IL-17A in Th17 cells. Antibodies targeting IL-23 or IL-17A are highly effective in the treatment of psoriasis, AS and PsA, validating the RORγt /Th17 pathway in human disease. VTP-43742 is an orally active inhibitor of RORgt that is being pursued for the treatment of autoimmune disorders. VTP-43742 binds to RORγt with high affinity (K i =3.5 nM) and exhibits >1000-fold selectivity versus the RORa and RORβ isotypes. VTP-43742 inhibits Th17 differentiation and IL-17A secretion from mouse splenocytes (IC 50 =57 nM) without affecting Th1, Th2, or Treg cell differentiation. In the MOG35-55/CFA immunized mouse EAE model, orally dosed VTP-43742 significantly suppressed clinical symptoms, demyelination and mRNA expression of multiple inflammatory markers in the spinal cord. Importantly, VTP-43742 inhibits the secretion of IL-17A from activated hPBMCs (IC 50 =18 nM) and human whole blood (IC 50 =192 nM) from healthy and psoriatic donors. Further, VTP-43742 is well absorbed after oral administration in multiple animal species and has pharmacokinetics consistent with once-a-day dosing in humans.

VTP-43742 is a potent and selective RORγt blocker that demonstrates oral efficacy in a mouse model of autoimmunity through suppression of IL-17A production (THER7P.945)

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VTP-43742 is a potent and selective RORγt blocker that demonstrates oral efficacy in a mouse model of autoimmunity through suppression of IL-17A production (THER7P.945)