Identification of small molecule inhibitors of RANKL and TNF signalling as anti-inflammatory and antiresorptive agents in mice.

INTRODUCTION: Inflammatory joint diseases such as rheumatoid arthritis are associated with local bone erosions and systemic bone loss, mediated by increased osteoclastic activity. The receptor activator of nuclear factor (NF) κB ligand (RANKL) plays a key role in mediating inflammation-induced bone loss, whereas tumour necrosis factor (TNF) plays a central role in the inflammatory process. Here we tested whether a recently identified class of small molecule inhibitors of RANKL signalling (ABD compounds) also affect TNF signalling and whether these compounds inhibit inflammation in an animal model of rheumatoid arthritis. METHODS: The inhibitory effects of the ABD compounds on TNF-induced signalling were tested in mouse macrophage cultures by western blotting and in an NFκB luciferase-reporter cell line. The anti-inflammatory effects of the compounds were tested in the mouse collagen-induced arthritis model of rheumatoid arthritis. RESULTS: The ABD compounds ABD328 and ABD345 both inhibited TNF-induced activation of the NFκB pathway and the extracellular signal-regulated kinase (ERK) and Jun kinase (JNK) mitogen activated protein kinases (MAPKs). When tested in the mouse collagen-induced arthritis model of rheumatoid arthritis, the compounds suppressed inflammatory arthritis, inhibited joint destruction and prevented systemic bone loss. Furthermore, one of the compounds (ABD328) showed oral activity. CONCLUSIONS: Here we describe a novel class of small molecule compounds that inhibit both RANKL- and TNF-induced NFκB and MAPK signalling in osteoclasts and macrophages, and inflammation and bone destruction in a mouse model of rheumatoid arthritis. These novel compounds therefore represent a promising new class of treatments for inflammatory diseases, such as rheumatoid arthritis.

Development of triarylsulfonamides as novel anti-inflammatory agents.

Triaylsulfonamides were identified as novel anti-inflammatory agents, acting by inhibition of RANKL and TNFα signaling. Structure-activity studies led to the identification of compounds with in vitro potencies of <100 nM against J774 macrophages and osteoclasts, but with little activity against osteoblasts or hepatocytes (IC(50) >50 µM). A representative compound (4k, ABD455) was able to completely prevent inflammation in vivo in a prevention model and was highly effective at controlling inflammation in a treatment model.

The biphenyl-carboxylate derivative ABD328 is a novel orally active antiresorptive agent.

We previously described a novel series of biphenyl carboxylic acid derivatives which have potent antiresorptive effects in vitro and in vivo and do not affect osteoblast function. However, none of the previous compounds showed oral activity, probably because they were esters, which would be expected to be metabolized very rapidly. Here, we tested whether derivatives where the ester link was replaced by a ketone link were orally active. Compounds were tested in murine osteoclast and osteoblast cultures and in the mouse ovariectomy (OVX) model of osteoporosis. The ketones were at least as potent at inhibiting osteoclast formation and RANKL signaling in vitro as the esters and did not inhibit osteoblast differentiation or function. The basic ketone-linked compound ABD68 was only partially able to inhibit OVX-induced bone loss at an oral dose of 20 mg/kg daily. Substitutions on the phenyl rings increased the potency of the compounds in vitro and may prevent metabolism of the compounds in vivo. The most promising derivative, ABD328, completely prevented OVX-induced bone loss when administered by intraperitoneal injection at 3 mg/kg daily. Furthermore, ABD328 was also able to fully prevent OVX-induced bone loss when given orally at 10 mg/kg daily. The results indicate that biphenyl carboxylates like ABD328 are oral candidate drugs for the treatment of diseases characterized by increased bone resorption, such as postmenopausal osteoporosis.

Discovery of biphenylketones as dual modulators of inflammation and bone loss.

Biphenylketones were identified as novel inhibitors of NFkappaB activation. Structure-activity studies led to the identification of compound 4c, which had good potency against osteoclasts (IC50=0.8 microM), showed oral activity, and was able to completely prevent inflammation and bone loss in vivo.

Bone marrow microenvironment controls the in vivo differentiation of murine dendritic cells into osteoclasts.

Finding that activated T cells control osteoclast (OCL) differentiation has revealed the importance of the interactions between immune and bone cells. Dendritic cells (DCs) are responsible for T-cell activation and share common precursors with OCLs. Here we show that DCs participate in bone resorption more directly than simply through T-cell activation. We show that, among the splenic DC subsets, the conventional DCs have the higher osteoclastogenic potential in vitro. We demonstrate that conventional DCs differentiate into functional OCLs in vivo when injected into osteopetrotic oc/oc mice defective in OCL resorptive function. Moreover, this differentiation involves the presence of activated CD4(+) T cells controlling a high RANK-L expression by bone marrow stromal cells. Our results open new insights in the differentiation of OCLs and DCs and offer new basis for analyzing the relations between bone and immune systems.

[Forecast of physician workforce in the 22 French regions (1998-2013)]. / Projection régionale du corps médical français (1998-2013).

The first chapter provides detailed information on the methodology and data used. As were the other projections carried out in the past by the Centre de sociologie et de démographie médicales, the present work is basically a demographic projection. Whereas a projection of national workforce uses the total number of annual new graduates as inflow, a regional projection has to collect other types of data, as new graduates move freely from one region to another. This fundamental difference implies the use of more complex models for predicting the flows of newcomers at regional level. As concerns the outflow, a single table covering retirement and death is used for all regions. The medical profession is a homogeneous group and such a decision is not irrelevant. The second chapter presents briefly the results of the work as concerns one region. In the high variant, the regional number of physicians will continue to increase from 1998 to 2007 or 2008, then it will decrease. In the low variant, the growth will end in 2004 or 2005, followed by a stronger decreasing process. The decrease is caused by the "graduate boom" cohorts (doctors graduated during the 70's and 80's) reaching retirement age. Given the duration of medical training, the decrease will take place even if the numerous clausus (at the start of medical training) rises steadily right now. The decrease in the number of physicians will be accompanied by an aging process: the proportion of senior active doctors will raise and that of junior doctors will diminish. The third chapter evidences the diversity of the various regional trends.