An assessment of ADAMs in bone cells: absence of TACE activity prevents osteoclast recruitment and the formation of the marrow cavity in developing long bones

AbstractADAMs (A Disintegrin And Metalloprotease domain) are metalloprotease–disintegrin proteins that have been implicated in cell adhesion, protein ectodomain shedding, matrix protein degradation and cell fusion. Since such events are critical for bone resorption and osteoclast recruitment, we investigated whether they require ADAMs. We report here which ADAMs we have identified in bone cells, as well as our analysis of the generation, migration and resorptive activity of osteoclasts in developing metatarsals of mouse embryos lacking catalytically active ADAM 17 [TNFα converting enzyme (TACE)]. The absence of TACE activity still allowed the generation of cells showing an osteoclastic phenotype, but prevented their migration into the core of the diaphysis and the subsequent formation of marrow cavity. This suggests a role of TACE in the recruitment of osteoclasts to future resorption sites

Potential of Resveratrol Analogues as Antagonists of Osteoclasts and Promoters of Osteoblasts

The plant phytoalexin resveratrol was previously demonstrated to inhibit the differentiation and bone resorbing activity of osteoclasts, to promote the formation of osteoblasts from mesenchymal precursors in cultures, and inhibit myeloma cell proliferation, when used at high concentrations. In the current study, we screened five structurally modified resveratrol analogues for their ability to modify the differentiation of osteoclasts and osteoblasts and proliferation of myeloma cells. Compared to resveratrol, analogues showed an up to 5,000-fold increased potency to inhibit osteoclast differentiation. To a lesser extent, resveratrol analogues also promoted osteoblast maturation. However, they did not antagonize the proliferation of myeloma cells. The potency of the best-performing candidate in vitro was tested in vivo in an ovariectomy-induced model of osteoporosis, but an effect on bone loss could not be detected. Based on their powerful antiresorptive activity in vitro, resveratrol analogues might be attractive modulators of bone remodeling. However, further studies are required to establish their efficacy in vivo

A recombinant Sal k 1 isoform as an alternative to the polymorphic allergen from Salsola kali pollen for allergy diagnosis

Amaranthaceae pollen allergy incidence has increased in the last years due to the desertification process occurring in many countries. In some regions of Spain,Salsola kali is the main cause of pollinosis at almost the same level than olive and grass pollen.Sal k 1 -the sensitization marker of S. kali pollinosis- is actually used in clinical diagnosis, but it is purified at a low yield from pollen. Thus, the aim of the study consists of the production of a recombinant isoform of Sal k 1 able to span the structural and immunological properties of the natural isoforms present in S. kali pollen and validate its potential use for diagnosis. Methods: Sal k 1-encoding cDNA was amplified by PCR, cloned in pET41b vector and used to transform BL21(DE3) E. coli cells to produce the recombinant allergen. Immunoblotting, ELISA, basophil activation and skin prick test were used to validate the recombinant protein against Sal k 1 isolated from pollen. Sera and blood cells from S. kali pollen sensitized patients and anti-Sal k 1 monoclonal and polyclonal antisera were used. Results: rSal k 1 was produced in E. coli with a final yield of 7.5 mg/L of cell culture. The expressed protein was isolated,purified to homogeneity, and structurally and immunologically validated against the natural form –nSal k 1- isolated from pollen as a useful diagnostic tool. In addition, Sal k 1 exhibited a higher IgE cross-reactivity with plant-derived food extracts such as peanut, almond or tomato than with related and non-related pollen sources such as P.acerifolia and Oleaceae members. Conclusions: rSal k 1 expressed in bacteria maintains its structural and immunological properties intact in comparison to nSal k 1.rSal k 1 spans the immunological properties of most of the natural isoforms found in pollen, and thus, might substitute nSal k 1 in clinical diagnosis