Background: Mechanical stimulation prevents osteocyte apoptosis and activates Wnt signaling. Results: ERK-mediated anti-apoptosis is abolished by antagonists of Wnt signaling, and conversely, ␤-catenin accumulation is blocked by inhibiting the caveolin-1/ERK pathway. Conclusion: Caveolin-1/ERK and Wnt/␤-catenin signaling pathways cooperate in transducing mechanical cues into osteocyte survival. Significance: This novel bidirectional crosstalk might be targeted to increase bone strength by preserving osteocyte viability.

Osteocytes have a major role in the control of bone remodeling. Mechanical stimulation decreases osteocyte apoptosis and promotes bone accrual, whereas skeletal unloading is deleterious in both respects. PTH1R ablation or overexpression in osteocytes in mice produces trabecular bone loss or increases bone mass, respectively. The latter effect was related to a decreased osteocyte apoptosis. Here, the putative role of PTH1R activation in osteocyte protection conferred by mechanical stimulation was assessed. Osteocytic MLO-Y4 cells were subjected to mechanical stimuli represented by hypotonic shock (216 mOsm/kg) or pulsatile fluid flow (8 Hz, 10 dynes/cm 2 ) for a short pulse (10 min), with or without PTH1R antagonists or after transfection with specific PTHrP or PTH1R siRNA. These mechanical stimuli prevented cell death induced within 6 hours by etoposide (50 mM), related to PTHrP overexpression; and this effect was abolished by the calcium antagonist verapamil (1 mM), a phospholipase C (PLC) inhibitor (U73122; 10 mM), and a PKA activation inhibitor, Rp-cAMPS (25 mM), in these cells. Each mechanical stimulus also rapidly induced b-catenin stabilization and nuclear ERK translocation, which were inhibited by the PTH1R antagonist PTHrP(7-34) (1 mM), or PTH1R siRNA, and mimicked by PTHrP(1-36) (100 nM). Mechanical stretching by hypotonic shock did not affect cAMP production but rapidly (<1 min) stimulated Ca i 2þ transients in PTH1R-overexpressing HEK-293 cells and in MLO-Y4 cells, in which calcium signaling was unaffected by the presence of a PTHrP antiserum or PTHrP siRNA but inhibited by knocking down PTH1R. These novel findings indicate that PTH1R is an important component of mechanical signal transduction in osteocytic MLO-Y4 cells, and that PTH1R activation by PTHrPindependent and dependent mechanisms has a relevant role in the prosurvival action of mechanical stimulus in these cells.

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BackgroundMultiple sclerosis is a widespread inflammatory demyelinating disease. Several immunomodulatory therapies are available, including interferon-β, glatiramer acetate, natalizumab, fingolimod, and mitoxantrone. Although useful to delay disease progression, they do not provide a definitive cure and are associated with some undesirable side-effects. Accordingly, the search for new therapeutic methods constitutes an active investigation field. The use of mesenchymal stem cells (MSCs) to modify the disease course is currently the subject of intense interest. Decidua-derived MSCs (DMSCs) are a cell population obtained from human placental extraembryonic membranes able to differentiate into the three germ layers. This study explores the therapeutic potential of DMSCs.MethodsWe used the experimental autoimmune encephalomyelitis (EAE) animal model to evaluate the effect of DMSCs on clinical signs of the disease and on the presence of inflammatory infiltrates in the central nervous system. We also compared the inflammatory profile of spleen T cells from DMSC-treated mice with that of EAE control animals, and the influence of DMSCs on the in vitro definition of the Th17 phenotype. Furthermore, we analyzed the effects on the presence of some critical cell types in central nervous system infiltrates.ResultsPreventive intraperitoneal injection of DMSCs resulted in a significant delay of external signs of EAE. In addition, treatment of animals already presenting with moderate symptoms resulted in mild EAE with reduced disease scores. Besides decreased inflammatory infiltration, diminished percentages of CD4+IL17+, CD11b+Ly6G+ and CD11b+Ly6C+ cells were found in infiltrates of treated animals. Early immune response was mitigated, with spleen cells of DMSC-treated mice displaying low proliferative response to antigen, decreased production of interleukin (IL)-17, and increased production of the anti-inflammatory cytokines IL-4 and IL-10. Moreover, lower RORγT and higher GATA-3 expression levels were detected in DMSC-treated mice. DMSCs also showed a detrimental influence on the in vitro definition of the Th17 phenotype.ConclusionsDMSCs modulated the clinical course of EAE, modified the frequency and cell composition of the central nervous system infiltrates during the disease, and mediated an impairment of Th17 phenotype establishment in favor of the Th2 subtype. These results suggest that DMSCs might provide a new cell-based therapy for the control of multiple sclerosis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0304-5) contains supplementary material, which is available to authorized users.

Background and Purpose PDE4 inhibition suppresses experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). However, side effects hinder PDE4 inhibitors clinical use. PDE7 inhibition might constitute an alternative therapeutic strategy, but few data about the anti‐inflammatory potential of PDE7 inhibitors are currently available. We have used the EAE model to perform a comparative evaluation of PDE4 and PDE7 inhibition as strategies for MS treatment. Experimental Approach Two PDE7 inhibitors, the sulfonamide derivative BRL50481 and the recently described quinazoline compound TC3.6, were assayed to modulate EAE in SJL mice, in comparison with the well‐known PDE4 inhibitor Rolipram. We evaluated clinical signs, presence of inflammatory infiltrates in CNS and anti‐inflammatory markers. We also analysed the effect of these inhibitors on the inflammatory profile of spleen cells in vitro. Key Results TC3.6 prevented EAE with efficacy similar to Rolipram, while BRL50481 had no effect on the disease. Differences between both PDE7 inhibitors are discussed. Data from Rolipram and TC3.6 showed that PDE4 and PDE7 inhibition work through both common and distinct pathways. Rolipram administration caused an increase in IL‐10 and IL‐27 expression which was not found after TC3.6 treatment. On the other hand, both inhibitors reduced IL‐17 levels, prevented infiltration in CNS and increased the expression of the T regulator cell marker Foxp3. Conclusions and Implications These results provide new information about the effects of Rolipram on EAE, underline PDE7 inhibition as a new therapeutic target for inflammatory diseases and show the value of TC3.6 to prevent EAE, with possible consequences for new therapeutic tools in MS.