RESUMEN
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.
Asunto(s)
Artritis/metabolismo , Huesos/metabolismo , Núcleo Celular/fisiología , Glomerulonefritis/metabolismo , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/fisiología , Macrófagos/metabolismo , Animales , Artritis/patología , Resorción Ósea/metabolismo , Huesos/inmunología , Señalización del Calcio , Células Cultivadas , Redes Reguladoras de Genes , Glomerulonefritis/inmunología , Homeostasis , Humanos , Ratones Noqueados , Ratas Endogámicas Lew , Ratas Endogámicas WKY , Receptores Inmunológicos/metabolismoRESUMEN
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.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Ácidos Hidroxámicos/farmacología , Inhibidores de la Metaloproteinasa de la Matriz , Animales , Biomarcadores Farmacológicos/análisis , Evaluación Preclínica de Medicamentos/métodos , Inhibidores Enzimáticos/toxicidad , Ácidos Hidroxámicos/toxicidad , Articulaciones/efectos de los fármacos , Articulaciones/patología , Estudios Longitudinales , Masculino , Enfermedades Musculoesqueléticas/inducido químicamente , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/patología , Sistema Musculoesquelético/efectos de los fármacos , Sistema Musculoesquelético/patología , Ratas , Ratas Sprague-DawleyRESUMEN
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.