Dissociation of Osteogenic and Immunological Effects by the Selective Glucocorticoid Receptor Agonist, Compound A, in Human Bone Marrow Stromal Cells

Abstract

Glucocorticoids (GCs) regulate various physiological processes, including bone remodeling. Whereas physiological amounts of GCs are required for proper human osteoblast differentiation, prolonged exposure to GCs leads to substantial bone loss in vivo predominantly by inhibiting osteoblast functions. Compound A (CpdA) is a novel GC receptor modulator with the potential of an improved benefit/risk profile. Here we tested the osteoimmunological effects of CpdA on primary human osteoblasts and their paracrine interactions with osteoclasts. To assess the antiinflammatory potential of CpdA in human bone marrow stromal cell (BMSC)-derived osteoblasts, cells were stimulated with lipopolysaccharide and cytokine expression was determined. Similar to dexamethasone (DEX), CpdA profoundly suppressed lipopolysaccharide-induced TNF-α (-63%), IL-1β (-38%), and IL-6 (-36%) (P < 0.05) mRNA levels. Of note, CpdA failed to induce osteogenic differentiation of BMSCs, whereas DEX and budesonide enhanced matrix mineralization an d increased runt-related transcription factor 2 and alkaline phosphatase mRNA levels up to 5-fold in a dose-dependent manner. Interestingly, each substance promoted cell proliferation by 7-10% and suppressed apoptosis by 25-30% at low concentrations and early differentiation stages, whereas high concentrations (1 μm) suppressed proliferation and stimulated apoptosis in mature osteoblasts. Finally, CpdA did not increase the receptor activator of nuclear factor-κB ligand to osteoprotegerin mRNA ratio as compared with DEX and did not stimulate the formation of osteoclasts in coculture with BMSCs. In summary, CpdA displays dissociated osteogenic and immunological effects in human BMSCs that are distinct from those of conventional GCs. Whether the specific osteoimmunological profile of CpdA translates into a relevant in vivo effect needs to be further explored.

Effect of the Plant Derivative Compound A on the Production of Corticosteroid-Resistant Chemokines in Airway Smooth Muscle Cells

“…The fact that a previous report in intestinal Caco-2 cell line showed no effect of CpdA on MKP-1 expression (35) suggests that the cellular effects of CpdA are highly cell specific. Indeed, we also failed to see any GRa nuclear translocation after CpdA treatment (Figure 4), contrasting with studies (mostly from De Bosscher and collaborators) that reported GRa nuclear translocation after CpdA treatment in different cell types (17,18,28,35,38). The reasons for this discrepancy are not known, but GRa activation by CpdA appears to be highly diverse with profound differences in the kinetic of GRa nuclear translocation (seen at 30 min and at 3-6 h) and CpdA potency (concentrations from 10 nM and up to 20 mM).…”

Effects of the Selective Glucocorticoid Receptor Modulator Compound A on Bone Metabolism and Inflammation in Male Mice With Collagen-Induced Arthritis

“…However, none of these studies examined its effects on bone. In our previous work, we have reported on the bonesparing potential of CpdA in vitro and in vivo (9,21,25), showing that CpdA maintains bone mass in a model of GC-induced bone loss because it does not interfere with bone formation or resorption (21).…”

“…None of these studies, however, have addressed the effects of CpdA on the skeleton. In initial studies on bone cells, CpdA, in contrast to conventional GCs, did not increase the receptor activator of NF-B ligand to osteoprotegerin ratio or stimulate osteoclastogenesis in vitro (9). Furthermore, no suppressive effects of osteoblast function were found (9,25).…”

“…In initial studies on bone cells, CpdA, in contrast to conventional GCs, did not increase the receptor activator of NF-B ligand to osteoprotegerin ratio or stimulate osteoclastogenesis in vitro (9). Furthermore, no suppressive effects of osteoblast function were found (9,25). Finally, CpdA maintained bone mineral density (BMD) in a mouse model of GC-induced bone loss, whereas prednisolone decreased BMD by 24% (21).…”

Nuclear factor of activated T cells mediates oxidised LDL-induced calcification of vascular smooth muscle cells

“…Osteoblast mineralisation Primary human bone marrow stromal cells (BMSCs) were kindly provided by the Department of Medicine I of the Dresden University Medical Center and cultured according to previously reported methods [28]. BMSCs were maintained in DMEM, 10% fetal calf serum (Supreme, Lonza, Cologne, Germany) and 1% penicillin/streptomycin in a humidified atmosphere of 95% air and 5% CO 2 .…”