Distinct immune modulatory roles of regulatory T cells in gut versus joint inflammation in TNF-driven spondyloarthritis.

OBJECTIVES: Gut and joint inflammation commonly co-occur in spondyloarthritis (SpA) which strongly restricts therapeutic modalities. The immunobiology underlying differences between gut and joint immune regulation, however, is poorly understood. We therefore assessed the immunoregulatory role of CD4+FOXP3+ regulatory T (Treg) cells in a model of Crohn's-like ileitis and concomitant arthritis. METHODS: RNA-sequencing and flow cytometry was performed on inflamed gut and joint samples and tissue-derived Tregs from tumour necrosis factor (TNF)∆ARE mice. In situ hybridisation of TNF and its receptors (TNFR) was applied to human SpA gut biopsies. Soluble TNFR (sTNFR) levels were measured in serum of mice and patients with SpA and controls. Treg function was explored by in vitro cocultures and in vivo by conditional Treg depletion. RESULTS: Chronic TNF exposure induced several TNF superfamily (TNFSF) members (4-1BBL, TWEAK and TRAIL) in synovium and ileum in a site-specific manner. Elevated TNFR2 messenger RNA levels were noted in TNF∆ARE/+ mice leading to increased sTNFR2 release. Likewise, sTNFR2 levels were higher in patients with SpA with gut inflammation and distinct from inflammatory and healthy controls. Tregs accumulated at both gut and joints of TNF∆ARE mice, yet their TNFR2 expression and suppressive function was significantly lower in synovium versus ileum. In line herewith, synovial and intestinal Tregs displayed a distinct transcriptional profile with tissue-restricted TNFSF receptor and p38MAPK gene expression. CONCLUSIONS: These data point to profound differences in immune-regulation between Crohn's ileitis and peripheral arthritis. Whereas Tregs control ileitis they fail to dampen joint inflammation. Synovial resident Tregs are particularly maladapted to chronic TNF exposure.

Paradoxical Augmentation of Experimental Spondyloarthritis by RORC Inhibition in HLA-B27 Transgenic Rats.

Objective: IL-17A plays a major role in the pathogenesis of spondyloarthritis (SpA). Here we assessed the impact of inhibition of RAR related orphan receptor-γ (RORC), the key transcription factor controlling IL-17 production, on experimental SpA in HLA-B27 transgenic (tg) rats. Methods: Experimental SpA was induced by immunization of HLA-B27 tg rats with heat-inactivated Mycobacterium tuberculosis. Splenocytes obtained at day 7, 14 and 21 after immunization were restimulated ex vivo to assess the induction of pro-inflammatory cytokines. Rats were then prophylactically treated with a RORC inhibitor versus vehicle control. The biologic effect of RORC inhibition was assessed by pro-inflammatory cytokine expression in draining lymph nodes. Arthritis and spondylitis were monitored clinically, and the degree of peripheral and axial inflammation, destruction and new bone formation was confirmed by histology. Results: Ex vivo mRNA and protein analyses revealed the rapid and selective induction of IL-17A and IL-22 production by a variety of lymphocyte subsets upon disease induction in HLA-B27 tg rats. Prophylactic RORC inhibition in vivo suppressed the expression of IL-17A, IL17F, and IL-22 without affecting the expression of other T helper cell subset related genes. This biological effect did not translate into clinical efficacy as RORC inhibition significantly accelerated the onset of arthritis and spondylitis, and aggravated the clinical severity of arthritis. This worsening of experimental SpA was confirmed by histopathological demonstration of increased inflammation, destruction, and new bone formation. Conclusion: Despite a significant suppression of the IL-17 axis, RORC inhibitor treatment accelerates and aggravates experimental SpA in the HLA-B27 tg rat model.

Clinical profile of the functionally selective glucocorticoid receptor agonist BI 653048 in healthy male subjects.

BACKGROUND: An efficacious anti-inflammatory corticosteroid with reduced side effects has been long sought. We report the pooled results from three clinical proof-of-mechanism Phase I studies of BI 653048 in healthy subjects, a functionally selective, nonsteroidal glucocorticoid (GC). RESEARCH DESIGN AND METHODS: Three Phase I trials were conducted: a single rising-dose study and a multiple rising-dose study to evaluate the safety, tolerability, and pharmacokinetics of BI 653048, and a multiple parallel-arm-dose study with intravenous lipopolysaccharide challenge to assess in vivo pharmacodynamics. The pharmacodynamics, efficacy, and safety of BI 653048 and prednisolone were compared. RESULTS: Treatment with 200 mg BI 653048 was associated with a reduced expression of IL1R2, ITGB3, and SDPR versus 20 mg prednisolone; comparable levels of FKBP5, ZBTB16, and DDIT4 expression were observed. Changes in C-peptide, glucose, insulin, and cortisol were moderate compared with prednisolone. A greater reduction of osteocalcin was observed with 200 mg BI 653048 versus 20 mg prednisolone. Comparable anti-inflammatory efficacy was demonstrated for 200 mg BI 653048 and 20 mg prednisolone. BI 653048 was well tolerated in healthy subjects. CONCLUSION: BI 653048 demonstrated the desired anti-inflammatory effects of the nonsteroidal GC; however, the undesirable side-effect profile associated with GC steroids could not be disassociated from BI 653048. TRIAL REGISTRATION: ClinicalTrials.gov identifiers NCT02217644, NCT02217631, and NCT02224105.

RORγt inhibition selectively targets IL-17 producing iNKT and γδ-T cells enriched in Spondyloarthritis patients.

Dysregulated IL-23/IL-17 responses have been linked to psoriatic arthritis and other forms of spondyloarthritides (SpA). RORγt, the key Thelper17 (Th17) cell transcriptional regulator, is also expressed by subsets of innate-like T cells, including invariant natural killer T (iNKT) and γδ-T cells, but their contribution to SpA is still unclear. Here we describe the presence of particular RORγt+T-betloPLZF- iNKT and γδ-hi T cell subsets in healthy peripheral blood. RORγt+ iNKT and γδ-hi T cells show IL-23 mediated Th17-like immune responses and were clearly enriched within inflamed joints of SpA patients where they act as major IL-17 secretors. SpA derived iNKT and γδ-T cells showed unique and Th17-skewed phenotype and gene expression profiles. Strikingly, RORγt inhibition blocked γδ17 and iNKT17 cell function while selectively sparing IL-22+ subsets. Overall, our findings highlight a unique diversity of human RORγt+ T cells and underscore the potential of RORγt antagonism to modulate aberrant type 17 responses.

An RORγt Oral Inhibitor Modulates IL-17 Responses in Peripheral Blood and Intestinal Mucosa of Crohn's Disease Patients.

Background and Aims: Despite the negative results of blocking IL-17 in Crohn's disease (CD) patients, selective modulation of Th17-dependent responses warrants further study. Inhibition of retinoic acid-related orphan receptor gamma (RORγt), the master regulator of the Th17 signature, is currently being explored in inflammatory diseases. Our aim was to determine the effect of a novel oral RORγt antagonist (BI119) in human CD and on an experimental model of intestinal inflammation. Methods: 51 CD patients and 11 healthy subjects were included. The effects of BI119 were tested on microbial-stimulated peripheral blood mononuclear cells (PBMCs), intestinal crypts and biopsies from CD patients. The ability of BI119 to prevent colitis in vivo was assessed in the CD4+CD45RBhigh T cell transfer model. Results: In bacterial antigen-stimulated PBMCs from CD patients, BI119 inhibits Th17-related genes and proteins, while upregulating Treg and preserving Th1 and Th2 signatures. Intestinal crypts cultured with supernatants from BI119-treated commensal-specific CD4+ T cells showed decreased expression of CXCL1, CXCL8 and CCL20. BI119 significantly reduced IL17 and IL26 transcription in colonic and ileal CD biopsies and did not affect IL22. BI119 has a more profound effect in ileal CD with additional significant downregulation of IL23R, CSF2, CXCL1, CXCL8, and S100A8, and upregulation of DEFA5. BI119 significantly prevented development of clinical, macroscopic and molecular markers of colitis in the T-cell transfer model. Conclusions: BI119 modulated CD-relevant Th17 signatures, including downregulation of IL23R while preserving mucosa-associated IL-22 responses, and abrogated experimental colitis. Our results provide support to the use of RORγt antagonists as a novel therapy to CD treatment.

BTK inhibition ameliorates kidney disease in spontaneous lupus nephritis.

Lupus nephritis is a common disease manifestation of SLE, in which immune complex deposition and macrophage activation are important contributors to disease pathogenesis. Bruton's tyrosine kinase (BTK) plays an important role in both B cell and FcgammaR mediated myeloid cell activation. In the current study, we examined the efficacy of BI-BTK-1, a recently described irreversible BTK inhibitor, in the classical NZB × NZW F1 (NZB/W) and MRL/lpr spontaneous mouse models of SLE. NZB/W mice were randomly assigned to a treatment (0.3 mg/kg, 1 mg/kg, 3 mg/kg and 10 mg/kg) or control group and began treatment at 22 weeks of age. The experimental setup was similar in MRL/lpr mice, but with a single treated (10 mg/kg, beginning at 8-9 weeks of age) and control group. A separate experiment was performed in the MRL/lpr strain to assess the ability of BI-BTK-1 to reverse established kidney disease. Early treatment with BI-BTK-1 significantly protected NZB/W and MRL/lpr mice from the development of proteinuria, correlating with significant renal histological protection, decreased anti-DNA titers, and increased survival in both strains. BI-BTK-1 treated mice displayed a significant decrease in nephritis-associated inflammatory mediators (e.g. LCN2 and IL-6) in the kidney, combined with a significant inhibition of immune cell infiltration and accumulation. Importantly, BI-BTK-1 treatment resulted in the reversal of established kidney disease. BTK inhibition significantly reduced total B cell numbers and all B cell subsets (immature, transitional, follicular, marginal zone, and class switched) in the spleen of NZB/W mice. Overall, the significant efficacy of BI-BTK-1 in ameliorating multiple pathological endpoints associated with kidney disease in two distinct murine models of spontaneous lupus nephritis provides a strong rationale for BTK inhibition as a promising treatment approach for lupus nephritis.

Highly selective inhibition of Bruton's tyrosine kinase attenuates skin and brain disease in murine lupus.

BACKGROUND: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that affects different end organs, including skin and brain. We and others have previously shown the importance of macrophages in the pathogenesis of cutaneous and neuropsychiatric lupus. Additionally, autoantibodies produced by autoreactive B cells are thought to play a role in both the skin and central nervous system pathologies associated with SLE. METHODS: We used a novel inhibitor of Bruton's tyrosine kinase (BTK), BI-BTK-1, to target both macrophage and B cell function in the MRL-lpr/lpr murine model of SLE, and examined the effect of treatment on skin and brain disease. RESULTS: We found that treatment with BI-BTK-1 significantly attenuated the lupus associated cutaneous and neuropsychiatric disease phenotypes in MRL/lpr mice. Specifically, BI-BTK-1 treated mice had fewer macroscopic and microscopic skin lesions, reduced cutaneous cellular infiltration, and diminished inflammatory cytokine expression compared to control mice. BTK inhibition also significantly improved cognitive function, and decreased accumulation of T cells, B cells, and macrophages within the central nervous system, specifically the choroid plexus. CONCLUSIONS: Directed therapies may improve the response rate in lupus-driven target organ involvement, and decrease the dangerous side effects associated with global immunosuppression. Overall, our results suggest that inhibition of BTK may be a promising therapeutic option for cutaneous and neuropsychiatric disease associated with SLE.

Selective glucocorticoid receptor modulation inhibits cytokine responses in a canine model of mild endotoxemia.

Selective glucocorticoid receptor modulators (GRMs) promise to reduce adverse events of glucocorticoids while maintaining anti-inflammatory potency. The present study tested the anti-inflammatory activity of two novel non-steroidal GRMs (GRM1: BI 607812 BS, GRM2: BI 653048 BS*H3PO4) in comparison to prednisolone in a canine model of low dose endotoxemia. This study compared the anti-inflammatory and pharmacokinetic profile of escalating daily oral doses of GRM1 (1, 2.5, 5 and 10mg/kg) and GRM2 (0.1, 0.25 and 1mg/kg) with prednisolone (0.25 and 0.5mg/kg) and placebo after intravenous infusion of endotoxin (0.1µg/kg) to Beagle dogs. This was followed by a 14-day evaluation study of safety and pharmacokinetics. Endotoxin challenge increased TNF-α ∼2000-fold and interleukin-6 (IL-6) 100-fold. Prednisolone and both GRMs suppressed peak TNF-α and IL-6 by 71-82% as compared with placebo. The highest doses of GRM1 and GRM2 reduced the mean body temperature increase by ∼30%. The endotoxin-induced rise in plasma cortisol was strongly suppressed in all treatment groups. Pharmacokinetics of both GRMs were non-linear. Adverse effects of endotoxemia such as vomiting were mitigated by GRM2 and prednisolone, indicating an antiemetic effect. During the 14-day treatment period, the adverse event profile of both GRMs appeared to be similar to prednisolone. Both GRMs had anti-inflammatory effects comparable to prednisolone and showed good safety profiles. Compounds targeting the glucocorticoid receptor selectively may provide an alternative to traditional glucocorticoids in the treatment of inflammatory disease.

Interferon-γ Represses M2 Gene Expression in Human Macrophages by Disassembling Enhancers Bound by the Transcription Factor MAF.

Mechanisms by which interferon (IFN)-γ activates genes to promote macrophage activation are well studied, but little is known about mechanisms and functions of IFN-γ-mediated gene repression. We used an integrated transcriptomic and epigenomic approach to analyze chromatin accessibility, histone modifications, transcription-factor binding, and gene expression in IFN-γ-primed human macrophages. IFN-γ suppressed basal expression of genes corresponding to an "M2"-like homeostatic and reparative phenotype. IFN-γ repressed genes by suppressing the function of enhancers enriched for binding by transcription factor MAF. Mechanistically, IFN-γ disassembled a subset of enhancers by inducing coordinate suppression of binding by MAF, lineage-determining transcription factors, and chromatin accessibility. Genes associated with MAF-binding enhancers were suppressed in macrophages isolated from rheumatoid-arthritis patients, revealing a disease-associated signature of IFN-γ-mediated repression. These results identify enhancer inactivation and disassembly as a mechanism of IFN-γ-mediated gene repression and reveal that MAF regulates the macrophage enhancer landscape and is suppressed by IFN-γ to augment macrophage activation.

Comprehensive profiling analysis of actively resorbing osteoclasts identifies critical signaling pathways regulated by bone substrate.

As the only cells capable of efficiently resorbing bone, osteoclasts are central mediators of both normal bone remodeling and pathologies associates with excessive bone resorption. However, despite the clear evidence of interplay between osteoclasts and the bone surface in vivo, the role of the bone substrate in regulating osteoclast differentiation and activation at a molecular level has not been fully defined. Here, we present the first comprehensive expression profiles of osteoclasts differentiated on authentic resorbable bone substrates. This analysis has identified numerous critical pathways coordinately regulated by osteoclastogenic cytokines and bone substrate, including the transition from proliferation to differentiation, and sphingosine-1-phosphate signaling. Whilst, as expected, much of this program is dependent upon integrin beta 3, the pre-eminent mediator of osteoclast-bone interaction, a surprisingly significant portion of the bone substrate regulated expression signature is independent of this receptor. Together, these findings identify an important hitherto underappreciated role for bone substrate in osteoclastogenesis.

Optimization of drug-like properties of nonsteroidal glucocorticoid mimetics and identification of a clinical candidate.

A series of nonsteroidal "dissociated" glucocorticoid receptor agonists was optimized for drug-like properties such as cytochrome P450 inhibition, metabolic stability, aqueous solubility, and hERG ion channel inhibition. This effort culminated in the identification of the clinical candidate compound ( R )-39.

Kcnn4 is a regulator of macrophage multinucleation in bone homeostasis and inflammatory disease.

Macrophages can fuse to form osteoclasts in bone or multinucleate giant cells (MGCs) as part of the immune response. We use a systems genetics approach in rat macrophages to unravel their genetic determinants of multinucleation and investigate their role in both bone homeostasis and inflammatory disease. We identify a trans-regulated gene network associated with macrophage multinucleation and Kcnn4 as being the most significantly trans-regulated gene in the network and induced at the onset of fusion. Kcnn4 is required for osteoclast and MGC formation in rodents and humans. Genetic deletion of Kcnn4 reduces macrophage multinucleation through modulation of Ca(2+) signaling, increases bone mass, and improves clinical outcome in arthritis. Pharmacological blockade of Kcnn4 reduces experimental glomerulonephritis. Our data implicate Kcnn4 in macrophage multinucleation, identifying it as a potential therapeutic target for inhibition of bone resorption and chronic inflammation.

Discovery of a potent and dissociated non-steroidal glucocorticoid receptor agonist containing an alkyl carbinol pharmacophore.

Synthesis and structure-activity relationship (SAR) of a series of alkyl and cycloalkyl containing non-steroidal dissociated glucocorticoid receptor (GR) agonists is reported. This series of compounds was identified as part of an effort to replace the CF3 group in a scaffold represented by 1a. The study culminated in the identification of compound 14, a t-butyl containing derivative, which has shown potent activity for GR, selectivity against the progesterone receptor (PR) and the mineralocorticoid receptor (MR), in vitro anti-inflammatory activity in an IL-6 transrepression assay, and dissociation in a MMTV transactivation counter-screen. In a collagen-induced arthritis mouse model, 14 displayed prednisolone-like efficacy, and lower impact on body fat and free fatty acids than prednisolone at an equivalent anti-inflammatory dose.

Identification of highly efficacious glucocorticoid receptor agonists with a potential for reduced clinical bone side effects.

Synthesis and structure-activity relationship (SAR) of a series of nonsteroidal glucocorticoid receptor (GR) agonists are described. These compounds contain "diazaindole" moieties and display different transcriptional regulatory profiles in vitro and are considered "dissociated" between gene transrepression and transactivation. The lead optimization effort described in this article focused in particular on limiting the transactivation of genes which result in bone side effects and these were assessed in vitro in MG-63 osteosarcoma cells, leading to the identification of (R)-18 and (R)-21. These compounds maintained anti-inflammatory activity in vivo in collagen induced arthritis studies in mouse but had reduced effects on bone relevant parameters compared to the widely used synthetic glucocorticoid prednisolone 2 in vivo. To our knowledge, we are the first to report on selective glucocorticoid ligands with reduced bone loss in a preclinical in vivo model.

Function-regulating pharmacophores in a sulfonamide class of glucocorticoid receptor agonists.

A class of α-methyltryptamine sulfonamide glucocorticoid receptor (GR) modulators was optimized for agonist activity. The design of ligands was aided by molecular modeling, and key function-regulating pharmacophoric points were identified that are critical in achieving the desired agonist effect in cell based assays. Compound 27 was profiled in vitro and in vivo in models of inflammation. Analogs could be rapidly prepared in a parallel approach from aziridine building blocks.

Substituted phenyl as a steroid A-ring mimetic: providing agonist activity to a class of arylsulfonamide nonsteroidal glucocorticoid ligands.

A class of arylsulfonamide glucocorticoid receptor agonists that contains a substituted phenyl group as a steroid A-ring mimetic is reported. The structural design and SAR that provide the functional switching of a GR antagonist to an agonist is described. A combination of specific hydrogen bonding and lipophilic elements on the A-ring moiety is required to achieve potent GR agonist activity. This study culminated in the identification of compound 23 as a potent GR agonist with selectivity over the PR and MR nuclear hormone receptors.

The oxidase activity of vascular adhesion protein-1 (VAP-1) is essential for function.

Vascular adhesion protein-1 (VAP-1) has been implicated in the pathogenesis of inflammatory diseases and is suggested to play a role in immune cell trafficking. It is not clear whether this effect is mediated by the oxidase activity or by other features of the protein such as direct adhesion. In order to study the role of VAP-1 oxidase activity in vivo, we have generated mice carrying an oxidase activity-null VAP-1 protein. We demonstrate that the VAP-1 oxidase null mutant mice have a phenotype similar to the VAP-1 null mice in animal models of sterile peritonitis and antibody induced arthritis suggesting that the oxidase activity is responsible for the inflammatory function of VAP-1.

Non-steroidal dissociated glucocorticoid agonists: indoles as A-ring mimetics and function-regulating pharmacophores.

We report a SAR of non-steroidal glucocorticoid mimetics that utilize indoles as A-ring mimetics. Detailed SAR is discussed with a focus on improving PR and MR selectivity, GR agonism, and in vitro dissociation profile. SAR analysis led to compound (R)-33 which showed high PR and MR selectivity, potent agonist activity, and reduced transactivation activity in the MMTV and aromatase assays. The compound is equipotent to prednisolone in the LPS-TNF model of inflammation. In mouse CIA, at 30 mg/kg compound (R)-33 inhibited disease progression with an efficacy similar to the 3 mg/kg dose of prednisolone.

Functional biomarkers of musculoskeletal syndrome (MSS) for early in vivo screening of selective MMP-13 inhibitors.

INTRODUCTION: Long-term administration of non-selective matrix metalloproteinase (MMP) inhibitors, such as marimastat, in humans elicits musculoskeletal syndrome (MSS), a syndrome characterized by joint damage including pain, stiffness, and inflammation. This pathology is a significant obstacle to the clinical development of MMP inhibitors and in pre-clinical models MSS can be verified only after terminal histopathology. Consequently, we devised a longitudinal and functional readout of MSS in conscious rats treated with marimastat that was validated against terminal histological assessment. METHODS: MSS was induced by minipump infusion of marimastat (5-10mg/kg/day). In marimastat-treated or vehicle-control groups, three possible functional biomarkers were assessed: paw volume (PV), landing foot splay separation (LFSS), and rotarod performance (n=6 rats/group for each endpoint). RESULTS: Histologically, fibrosis scores in the synovium and ligament increased from 0 on Day 1 (D1) to 4.6±0.2 and 4.7±0.1, respectively, on D15; growth plate thickness was also elevated from 215.0±6.3µm (D1) to 253.3±8.0µm (D15). While neither PV nor LFSS were correlative with MSS histopathology, marimastat (10mg/kg/day) reduced rotarod performance from 180±0s (D0) to 135±30s (D9) using a constant speed protocol (10rpm, 180s) and from 180±0s (D0) to 96±6s (D6) employing a variable speed protocol (increasing from 5 to 25rpm over 180s). DISCUSSION: Results of the present study demonstrate that rotarod performance can be used as a predictive longitudinal, in vivo functional biomarker of MSS concomitant with histological evidence of joint damage to effectively facilitate compound selection during drug discovery. Moreover, for targets with a mechanistic risk for MSS, the model is also conducive to inclusion in secondary pharmacodynamic studies during lead optimization to identify the best (safest) compounds for advancement into clinical trials.

Nonsteroidal dissociated glucocorticoid agonists containing azaindoles as steroid A-ring mimetics.

Syntheses and structure-activity relationships (SAR) of nonsteroidal glucocorticoid receptor (GR) agonists are described. These compounds contain azaindole moieties as A-ring mimetics and display various degrees of in vitro dissociation between gene transrepression and transactivation. Collagen induced arthritis studies in mouse have demonstrated that in vitro dissociated compounds (R)-16 and (R)-37 have steroid-like anti-inflammatory properties with improved metabolic side effect profiles, such as a reduced increase in body fat and serum insulin levels, compared to steroids.