n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Arthritis--Rheumatoid

To test the hypothesis that Notch signalling plays a role in the pathogenesis of rheumatoid arthritis (RA) and to determine whether pharmacological inhibition of Notch signalling with γ-secretase inhibitors can ameliorate the RA disease process in an animal model.. Collagen-induced arthritis was induced in C57BL/6 or Notch antisense transgenic mice by immunisation with chicken type II collagen (CII). C57BL/6 mice were administered with different doses of inhibitors of γ-secretase, an enzyme required for Notch activation, at disease onset or after onset of symptoms. Severity of arthritis was monitored by clinical and histological scores, and in vivo non-invasive near-infrared fluorescence (NIRF) images. Micro-CT was used to confirm joint destruction. The levels of CII antibodies and cytokines in serum were determined by ELISA and bead-based cytokine assay. The expression levels of cytokines were studied by quantitative PCR in rheumatoid synovial fibroblasts.. The data show that Notch signalling stimulates synoviocytes and accelerates their production of proinflammatory cytokines and immune responses involving the upregulation of IgG1 and IgG2a. Pharmacological inhibition of γ-secretase and antisense-mediated knockdown of Notch attenuates the severity of inflammatory arthritis, including arthritis indices, paw thickness, tissue damage and neutrophil infiltration, and reduces the levels of active NF-κB, ICAM-1, proinflammatory cytokines and matrix metalloproteinase-3 activity in the mouse model of RA.. These results suggest that Notch is involved in the pathogenesis of RA and that inhibition of Notch signalling is a novel approach for treating RA.

Topics: Amyloid Precursor Protein Secretases; Animals; Arthritis, Experimental; Arthritis, Rheumatoid; Cytokines; Dipeptides; Disease Models, Animal; Mice; Mice, Inbred C57BL; Mice, Transgenic; Receptors, Notch; Severity of Illness Index; Signal Transduction; Synovial Membrane

NOTCH-dependent signaling pathways are critical for normal bone remodeling; however, it is unclear if dysfunctional NOTCH activation contributes to inflammation-mediated bone loss, as observed in rheumatoid arthritis (RA) patients. We performed RNA sequencing and pathway analyses in mesenchymal stem cells (MSCs) isolated from transgenic TNF-expressing mice, a model of RA, to identify pathways responsible for decreased osteoblast differentiation. 53 pathways were dysregulated in MSCs from RA mice, among which expression of genes encoding NOTCH pathway members and members of the noncanonical NF-κB pathway were markedly elevated. Administration of NOTCH inhibitors to RA mice prevented bone loss and osteoblast inhibition, and CFU-fibroblasts from RA mice treated with NOTCH inhibitors formed more new bone in recipient mice with tibial defects. Overexpression of the noncanonical NF-κB subunit p52 and RELB in a murine pluripotent stem cell line increased NOTCH intracellular domain-dependent (NICD-dependent) activation of an RBPjκ reporter and levels of the transcription factor HES1. TNF promoted p52/RELB binding to NICD, which enhanced binding at the RBPjκ site within the Hes1 promoter. Furthermore, MSC-enriched cells from RA patients exhibited elevated levels of HES1, p52, and RELB. Together, these data indicate that persistent NOTCH activation in MSCs contributes to decreased osteoblast differentiation associated with RA and suggest that NOTCH inhibitors could prevent inflammation-mediated bone loss.

Topics: Animals; Arthritis, Rheumatoid; Basic Helix-Loop-Helix Transcription Factors; Bone Resorption; Cell Differentiation; Dipeptides; Disease Models, Animal; Gene Expression; Homeodomain Proteins; Humans; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; NF-kappa B; NF-kappa B p52 Subunit; Osteoblasts; Promoter Regions, Genetic; Receptors, Notch; Signal Transduction; Transcription Factor HES-1; Transcription Factor RelB; Tumor Necrosis Factor-alpha

γ-Secretase inhibitors which prevent Notch activation are emerging as potent therapeutics for various inflammatory diseases, including ischemic stroke and rheumatoid arthritis. However, their indiscriminate distribution in the body causes serious side effects after systemic administration, since Notch proteins are ubiquitous receptors that play an important role in cellular functions such as differentiation, proliferation, and apoptosis. In this study, hyaluronan nanoparticles (HA-NPs) bearing a γ-secretase inhibitor (DAPT) were prepared as potential therapeutics for rheumatoid arthritis. In vivo biodistribution of the DAPT-loaded HA-NPs (DNPs), labeled with near-infrared dye, were observed using a non-invasive optical imaging system after systemic administration to a collagen-induced arthritis (CIA) mouse model. The results demonstrated that DNPs were effectively accumulated at the inflamed joint of the CIA mice. From the in vivo therapeutic efficacy tests, DNPs (1mg DAPT/kg) significantly attenuated the severity of RA induction compared to DAPT alone (2mg/kg), which was judged from clinical scores, tissue damage, and neutrophil infiltration. In addition, DNPs dramatically reduced the production of pro-inflammatory cytokines (TNF-α, IFN-γ, MCP-1, and IL-6, -12, -17) and collagen-specific auto-antibodies (IgG1 and IgG2a) in the serum of the CIA mice. These results suggest that DNPs have potential as therapeutics for rheumatoid arthritis.

Topics: Amyloid Precursor Protein Secretases; Animals; Arthritis, Rheumatoid; Cytokines; Dipeptides; Drug Carriers; Hyaluronic Acid; Knee Joint; Male; Mice; Nanoparticles