Gemcabene, a first-in-class lipid-lowering agent in late-stage development, down-regulates acute-phase C-reactive protein via C/EBP-δ-mediated transcriptional mechanism.

Inflammation plays a key role in setting the stage leading to atherosclerosis progression, and high-sensitivity C-reactive protein (CRP) has been recognized as a predictor of cardiovascular risk. As a monotherapy and in combination with statins, gemcabene markedly reduced CRP in humans. Present investigation was undertaken to understand the mechanism of CRP reduction. In human hepatoma cells, gemcabene inhibited IL-6 plus IL-1ß-induced CRP production in a concentration-dependent manner, reaching 70% inhibition at 2 mM. In TNF-α-stimulated primary human coronary artery endothelial cells, both CRP and IL-6 productions were reduced by 70% at 2 mM gemcabene concentration. To investigate the mechanism of gemcabene-mediated reduction of CRP, transfection studies were performed with human CRP regulatory sequences in luciferase/ß-gal system that showed 25-fold increase in IL-6- and IL-6 plus IL-1ß-stimulated CRP transcription. Luciferase activity was reduced by 50% by gemcabene, suggesting transcriptional down-regulation of CRP. Site-directed mutagenesis of human CRP promoter revealed that the overlapping downstream C/EBP and NF-κB binding sites are important for gemcabene-mediated CRP transcription. Gel shift assays identified the transcription factor that binds to the downstream CRP promoter as C/EBP-δ. In conclusion, gemcabene decreases CRP by C/EBP-δ and NF-κB-mediated transcriptional mechanism and suppresses IL-6 and IL-1ß-induced CRP production.

Reprint of BMCL_19101.

The pathogenesis of rheumatoid arthritis is mainly driven by NF-κB-mediated production of cytokines, such as TNF-α. We report herein that the orally available imidazoline-based NF-κB inhibitor, TCH-013, was found to significantly reduce TNF-α signaling and attenuate collagen antibody induced arthritis in BALB/c mice.

Attenuation of collagen-induced arthritis by orally available imidazoline-based NF-κB inhibitors.

The pathogenesis of rheumatoid arthritis is mainly driven by NF-κB-mediated production of cytokines, such as TNF-α. We report herein that the orally available imidazoline-based NF-κB inhibitor, TCH-013, was found to significantly reduce TNF-α signaling and attenuate collagen antibody induced arthritis in BALB/c mice.

Gemcabene, a First-in-Class Hypolipidemic Small Molecule in Clinical Development, Attenuates Osteoarthritis and Pain in Animal Models of Arthritis and Pain.

Our clinical studies have demonstrated that gemcabene, a small molecule in late-stage clinical development, lowers pro-inflammatory acute-phase protein, C-reactive protein (CRP). This observation was further confirmed in a cell-based study showing inhibition of cytokine-induced CRP production. Based on these observations, in the present study, we tested the hypothesis that gemcabene may possess anti-inflammatory activities in animal models of inflammatory disease. Efficacy of gemcabene was investigated in rat models of carrageenan-induced thermal hyperalgesia (CITH), monosodium iodoacetate (MIA)-induced osteoarthritis (OA), and IL-6/IL-6sR-induced inflammation. We also evaluated efficacy of gemcabene in collagen antibody-induced joint swelling and arthritis in BALB/c mice. In CITH rat model, gemcabene administration attenuated paw withdrawal latency (60% at 30 mg/kg/d and 97% at 100 mg/kg/d) and showed improvement in joint swelling (-50% at 30 mg/kg/d) in MIA model of OA. These findings were further corroborated by IL-6/IL-6sR knee injection model in rat, showing 63 and 71% reduction in hind paw weight distribution at 10 and 30 mg/kg/d doses, respectively. In mouse model of monoclonal antibody-induced arthritis, a dose-dependent attenuation of joint swelling was observed. These results demonstrate that the anti-inflammatory activity of gemcabene previously observed in cell-based and in clinical studies also occurred in animal models of inflammation-induced arthritis and hyperalgesia. Thus, in addition to hypolipidemic efficacy, the anti-inflammatory activity of gemcabene may have additional benefits to patients with elevated vascular inflammation.

Macrophage-specific expression of class A scavenger receptors in LDL receptor(-/-) mice decreases atherosclerosis and changes spleen morphology.

Class A scavenger receptors (SR-A) have been implicated in the atherogenic process, although there have been conflicting reports as to their specific effect on the development of lesions. In part, this discord may arise because of the variable contribution of SR-A in the several cell types known to express this protein. To determine the effects of macrophage-specific SR-A expression in the atherogenic process, transgenic mice were created using the chicken lysozyme (lyso) promoter to drive expression of bovine SR-A (bSR-A). To express this gene in an atherosclerosis-susceptible strain, bone marrow cells from transgenic and non-transgenic littermates were used to repopulate lethally-irradiated female LDL receptor (LDLr)(-/-) mice. Following hematopoietic engraftment, mice were placed on a diet enriched in saturated fat and cholesterol. After 8 weeks, there was a modest, but statistically significant reduction in serum total cholesterol in LDLr(-/-) mice repopulated with lyso-bSR-A transgenic cells, due to decreased LDL-cholesterol. The extent of atherosclerosis was reduced in both cross-sectional analysis of the aortic root and en face analysis of the intimal surface of the aortic arch. In addition to changes in atherosclerosis, lyso-bSR-A repopulated LDLr(-/-) mice had a marked increase (3.6x) in spleen weights and a disruption of spleen white pulp formation. Therefore, macrophage-specific overexpression of SR-A resulted in reduced atherosclerosis in two vascular beds, reduced serum cholesterol concentrations, and changed the morphology of the spleen.