Human CALCR ELISA Matched Antibody Pair

Lipopolysaccharide (LPS), the principal component of Gram-negative bacterial cell walls, is a stimulator of osteoclastogenesis and thus a key factor in inflammatory bone loss. We have recently reported that the important cholesterol and inflammatory regulator, liver X receptor (LXR alpha/beta), can potently inhibit osteoclast formation from bone marrow-derived osteoclast precursors in a bacterial/LPS environment. In this manuscript, we further studied the effect of the LXR agonist GW3965 on osteoclast differentiation in RAW264.7 promyelocytic leukemia cells exposed to LPS. We found that not only did activation of the LXR potently inhibit the formation of TRAP-positive osteoclast-like cells, but promoted a population of TRAP-negative mononuclear cells with high phagocytic activity. We observed reduced expression of the osteoclast markers TRAP/Acp5, Ctsk, Calcr and Oscar after 3-4 days of GW3965 treatment, coinciding with an increase in the expression of the anti-osteoclastogenic factor Irf8. Expression of the macrophage/phagocytic marker Cd68 was increased, however the "classical" macrophage markers F4/80 and Cd14 and the "alternatively" activated macrophage markers Tgf beta and Il10 were not altered. Further, activation of LXR increased the expression of the macrophage survival gene AIM/SP alpha, a known LXR target gene, and osteoclast/macrophage-related markers (Mitf, Pu.1, Usf1/2, Ostm1 and Mfr). Although Akt phosphorylation was reduced, GW3965 seemed to act independently of MAPKs (p38, ERK, JNK) and NF kappa B, and had no inhibitory effect on cytokine expression (Tnf alpha, Il6, or Il1 beta). Our results indicate that activation of the LXR not only inhibits the differentiation of osteoclast-like cells from RAW264.7 cells in a bacterial/LPS environment, but is also involved in the fate determination of myeloid progenitor cells into macrophages with high phagocytic capacity. (C) 2012 Elsevier Inc. All rights reserved.

Key metabolic hormones, such as insulin, leptin, and adiponectin, have been studied extensively in obesity, however the pathophysiologic relevance of the calcitonin family of peptides remains unclear. This family includes calcitonin (CT), its precursor procalcitonin (PCT), and alpha calcitonin-gene related peptide (aCGRP), which are all encoded by the gene Calca. Here, we studied the role of Calca-derived peptides in diet-induced obesity (DIO) by challenging Calcr(-/-) (encoding the calcitonin receptor, CTR), Calca(-/-), and aCGRP(-/-) mice and their respective littermates with high-fat diet (HFD) feeding for 16 weeks. HFD-induced pathologies were assessed by glucose tolerance, plasma cytokine and lipid markers, expression studies and histology. We found that DIO in mice lacking the CTR resulted in impaired glucose tolerance, features of enhanced nonalcoholic steatohepatitis (NASH) and adipose tissue inflammation compared to wildtype littermates. Furthermore, CTR-deficient mice were characterized by dyslipidemia and elevated HDL levels. In contrast, mice lacking Calca were protected from DIO, NASH and adipose tissue inflammation, and displayed improved glucose tolerance. Mice exclusively lacking aCGRP displayed a significantly less improved DIO phenotype compared to Calca-deficient mice. In summary, we demonstrate that the CT/CTR axis is involved in regulating plasma cholesterol levels while Calca, presumably through PCT, seems to have a detrimental effect in the context of metabolic disease. Our study provides the first comparative analyses of the roles of Calca-derived peptides and the CTR in metabolic disease.