Search

Abstract: Crohn''s disease (CD) is an inflammatory disease characterized by the activation of the immune system in the gut. Since tumor necrosis factor (TNF-α) plays an important role in the initiation and perpetuation of intestinal inflammation in CD, we investigated whether TX 527 [19-nor-14,20-bisepi-23-yne-1,25(OH)2D3], a Vitamin D analogue, could affect peripheral blood mononuclear cells (PBMC) proliferation and exert an immunosuppressive effect on TNF-α production in CD patients, and whether this immunosuppressive action could be mediated by NF-κB down-regulation. TX 527 significantly decreased cell proliferation and TNF-α levels. On activation, NF-κB, rapidly released from its cytoplasmatic inhibitor (IKB-α), transmigrates into the nucleus and binds to DNA response elements in gene promoter regions. The activation of NF-κB, stimulated by TNF-α, and its nuclear translocation together with the degradation of IKB-α were blocked by TX 527. At the same time, NF-κB protein levels present in cytoplasmic extracts decreased in the presence of TNF-α and increased when PBMC were incubated with TX 527. The results of our studies indicate that TX 527 inhibits TNF-α mediated effects on PBMC and the activation of NF-κB and that its action is mediated by Vitamin D receptor (VDR), which is activated when the cells are stimulated with TX 527. [Copyright &y& Elsevier]

Abstract: This study tested the hypothesis that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] plays a role in human umbilical vein endothelial cells (HUVEC) cultures. HUVEC were incubated with 10 or 100nM 1,25(OH)2D3 for 24h, in the absence or presence of 40ng/ml tumor necrosis factor-α (TNF-α) or 2ng/ml interleukin-1α (IL-1α). 1,25(OH)2D3 did not affect HUVEC viability and proliferation, while TNF-α, alone or in combination with the hormone, significantly inhibited HUVEC viability. [3H]thymidine incorporation in HUVEC treated with TNF-α or IL-1α significantly decreased, in the absence or in the presence of the hormone, while the levels of vitamin D receptor markedly increased in the presence of 1,25(OH)2D3 alone or associated with TNF-α or IL-1α, in comparison to the control. The noteworthy increase in protein levels of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) induced by TNF-α was significantly decreased after incubation of the cells with 1,25(OH)2D3, this effect not being seen on E-selectin expression. Neither apoptosis nor nuclear translocation of NF-κB, induced in HUVEC by TNF-α was influenced by 1,25(OH)2D3 treatment. [Copyright &y& Elsevier]

Transient receptor potential canonical (TRPC) channels provide cation and Ca2+ entry pathways, which have important regulatory roles in many physio-pathological processes, including muscle dystrophy. However, the mechanisms of activation of these channels remain poorly understood. Using siRNA, we provide the first experimental evidence that TRPC channel 1 (TRPC1), besides acting as a store-operated channel, represents an essential component of stretch-activated channels in C2C12 skeletal myoblasts, as assayed by whole-cell patch-clamp and atomic force microscopic pulling. The channel's activity and stretch-induced Ca2+ influx were modulated by sphingosine 1-phosphate (S1P), a bioactive lipid involved in satellite cell biology and tissue regeneration. We also found that TRPC1 was functionally assembled in lipid rafts, as shown by the fact that cholesterol depletion resulted in the reduction of transmembrane ion current and conductance. Association between TRPC1 and lipid rafts was increased by formation of stress fibres, which was elicited by S1P and abolished by treatment with the actin-disrupting dihydrocytochalasin B, suggesting a role for cytoskeleton in TRPC1 membrane recruitment. Moreover, TRPC1 expression was significantly upregulated during myogenesis, especially in the presence of S1P, implicating a crucial role for TRPC1 in myoblast differentiation. Collectively, these findings may offer new tools for understanding the role of TRPC1 and sphingolipid signalling in skeletal muscle regeneration and provide new therapeutic approaches for skeletal muscle disorders. [ABSTRACT FROM AUTHOR]