n4-(2-2-dimethyl-3-oxo-4h-pyrid(1-4)oxazin-6-yl)-5-fluoro-n2-(3-4-5-trimethoxyphenyl)-2-4-pyrimidinediamine and Disease-Models--Animal

Neuroinflammation is initiated in response to ischemic stroke, generally with the hallmarks of microglial activation and collateral brain injury contributed by robust inflammatory effects. Triggering receptor expressed on myeloid cells (TREM)-1, an amplifier of the innate immune response, is a critical regulator of inflammation. This study identified that microglial TREM-1 expression was upregulated following cerebral ischemic injury. After pharmacologic inhibition of TREM-1 with synthetic peptide LP17, ischemia-induced infarction and neuronal injury were substantially alleviated. Moreover, blockade of TREM-1 can potentiate cellular proliferation and synaptic plasticity in hippocampus, resulting in long-term functional improvement. Microglial M1 polarization and neutrophil recruitment were remarkably abrogated as mRNA levels of M1 markers, chemokines, and protein levels of myeloperoxidase and intracellular adhesion molecule-1 (ICAM-1) were decreased by LP17. Mechanistically, both in vivo and in vitro, we delineated that TREM-1 can activate downstream pro-inflammatory pathways, CARD9/NF-κB, and NLRP3/caspase-1, through interacting with spleen tyrosine kinase (SYK). In addition, TREM-1-induced SYK initiation was responsible for microglial pyroptosis by elevating levels of gasdermin D (GSDMD), N-terminal fragment of GSDMD (GSDMD-N), and forming GSDMD pores, which can facilitate the release of intracellular inflammatory factors, in microglia. In summary, microglial TREM-1 receptor yielded post-stroke neuroinflammatory damage via associating with SYK.

Topics: Animals; Behavior, Animal; Brain Ischemia; Disease Models, Animal; Inflammation; Male; Mice; Mice, Inbred C57BL; Microglia; Neutrophil Infiltration; Oxazines; Pyridines; Pyroptosis; Signal Transduction; Stroke; Syk Kinase; Transcriptome; Triggering Receptor Expressed on Myeloid Cells-1

Retinoblastoma is a childhood cancer of the retina. Clinical trials have shown that local delivery of broad spectrum chemotherapeutic agents is efficacious. Recent studies characterizing the genomic and epigenomic landscape of retinoblastoma identified spleen tyrosine kinase (SYK) as a promising candidate for targeted therapy. The purpose of this study was to conduct preclinical testing of the SYK antagonist R406 to evaluate it as a candidate for retinoblastoma treatment.. The efficacy of the SYK antagonist R406 delivered locally in a human orthotopic xenograft mouse model of retinoblastoma was tested. Intraocular exposure of R406 was determined for various routes and formulations.. There was no evidence of efficacy for subconjunctival. R406. Maximal vitreal concentration was 10-fold lower than the minimal concentration required to kill retinoblastoma cells in vitro. Dosage of R406 subconjunctivally from emulsion or suspension formulations, direct intravitreal injection of the soluble prodrug of R406 (R788), and repeated topical administration of R406 all increased vitreal exposure, but failed to reach the exposure required for retinoblastoma cell death in culture.. Taken together, these data suggest that R406 is not a viable clinical candidate for the treatment of retinoblastoma. This study highlights the importance of pharmacokinetic testing of molecular targeted retinoblastoma therapeutics.

Topics: Animals; Antineoplastic Agents; Cell Death; Disease Models, Animal; Eye; Female; Humans; Intracellular Signaling Peptides and Proteins; Mice; Mice, Inbred C57BL; Oxazines; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyridines; Retinal Neoplasms; Retinoblastoma; Syk Kinase

Antibody-mediated glomerulonephritis, including that resulting from immune complexes, is an important cause of renal failure and is in need of more specific and effective treatment. Binding of antibody or immune complexes to Fc receptors activates intracellular signal transduction pathways, including spleen tyrosine kinase (Syk), leading to the production of inflammatory cytokines. We examined the effect of R788 (fostamatinib disodium), an oral prodrug of the selective Syk inhibitor R406, in nephrotoxic nephritis in Wistar-Kyoto rats. Treatment with R788 reduced proteinuria, tissue injury, glomerular macrophage and CD8+ cell numbers, and renal monocyte chemoattractant protein-1 (MCP-1) and IL-1beta, even when we started treatment after the onset of glomerulonephritis. When we administered R788 from days 4 to 10, glomerular crescents reduced by 100% (P < 0.01) compared with the vehicle group. When we administered R788 treatment from days 7 to 14, established glomerular crescents reversed (reduced by 21%, P < 0.001), and renal function was better than the vehicle group (P < 0.001). In vitro, R406 downregulated MCP-1 production from mesangial cells and macrophages stimulated with aggregated IgG. These results suggest that Syk is an important therapeutic target for the treatment of glomerulonephritis.

Topics: Aminopyridines; Animals; Cells, Cultured; Chemokine CCL2; Disease Models, Animal; Glomerulonephritis; Interleukin-1beta; Intracellular Signaling Peptides and Proteins; Macrophages; Mesangial Cells; Morpholines; Oxazines; Protein-Tyrosine Kinases; Pyridines; Pyrimidines; Rats; Rats, Inbred WKY; Severity of Illness Index; Signal Transduction; Syk Kinase

Spleen tyrosine kinase (Syk), a key mediator of immunoreceptor signaling in inflammatory cells, is essential for immune complex-mediated signal transduction initiated by activated receptors for immunoglobulin G. In collagen-induced arthritis, R788/R406, a novel and potent small molecule Syk inhibitor suppressed clinical arthritis, bone erosions, pannus formation, and synovitis. Serum anti-collagen type II antibody levels were unaltered, while the half-life of exogenous antibody was extended when co-administered with R406. Expression of the targeted kinase (Syk) in synovial tissue correlated with the joint level of inflammatory cell infiltrates and was virtually undetectable in treated rats. Syk inhibition suppressed synovial cytokines and cartilage oligomeric matrix protein (COMP) in serum, suggesting a sensitive and reliable biomarker for R406 activity. These results highlight the role of activating Fcgamma receptors in inflammatory synovitis and suggest that interruption of the signaling cascade with a novel Syk inhibitor may be a useful addition to immunosuppressive disease-modifying anti-rheumatic drugs currently used in the treatment of human autoimmune diseases such as rheumatoid arthritis.

Topics: Aminopyridines; Animals; Arthritis, Rheumatoid; Arthus Reaction; Bone Resorption; Collagen Type II; Disease Models, Animal; Female; Immunoglobulin G; Inflammation; Intracellular Signaling Peptides and Proteins; Morpholines; Oxazines; Prodrugs; Protein-Tyrosine Kinases; Pyridines; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptors, IgG; Signal Transduction; Syk Kinase; Synovial Fluid; Synovitis