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In the adult skeleton, the bone remodeling process involves a dynamic coordination between osteoblasts and osteoclasts, which is disrupted in diseases with high bone turnover rates and dysregulated transforming growth factor beta 1 (TGF-b1). However, little is known about how TGF-b1 signaling mediates bone resorption. Here, we described a pedigree with a heterozygous variant in TGF-b1 (R218C) that resulted in aberrant activation of TGF-b1 through an activating mechanism that caused Camurati-Engelmann disease (CED). We showed that CED patients have high levels of active Rho GTPases and the migration-related proteins Integrin b1 and Integrin b3 in their peripheral blood. HEK293T cells transfected with a plasmid encoding this mutant expressed high levels of TGF-b1 and active Rho GTPases. Furthermore, activation of Rho by TGF-b1 increased osteoclast formation and bone resorption, with increased migration of pre-osteoclasts, as well as cytoskeletal remodeling of pre-osteoclasts and mature osteoclasts. Importantly, pharmacological inhibition of Rho GTPases effectively rescued hyperactive TGF-b1-induced osteoclastogenesis in vitro. Overall, we propose that Rho GTPases mediate TGF-b1-induced osteoclastogenesis and suggest that Rho-TGF-b1 crosstalk is associated with high bone turnover in CED. [ABSTRACT FROM AUTHOR]

Despite its high prevalence, the cellular and molecular mechanisms of chronic obstructive pulmonary disease (COPD) are far from being understood. Here, we determine disease-related changes in cellular and molecular compositions within the alveolar space and peripheral blood of a cohort of COPD patients and controls. Myeloid cells were the largest cellular compartment in the alveolar space with invading monocytes and proliferating macrophages elevated in COPD. Modeling cell-to-cell communication, signaling pathway usage, and transcription factor binding predicts TGF-b1 to be a major upstream regulator of transcriptional changes in alveolar macrophages of COPD patients. Functionally, macrophages in COPD showed reduced antigen presentation capacity, accumulation of cholesteryl ester, reduced cellular chemotaxis, and mitochondrial dysfunction, reminiscent of impaired immune activation. [ABSTRACT FROM AUTHOR]

Dkk-3 is a member of the dickkopf protein family of secreted inhibitors of the Wnt pathway, which has been shown to enhance angiogenesis. The mechanism underlying this effect is currently unknown. Here, we used cultured HUVECs to study the involvement of the TGF-b and VEGF on the angiogenic effect of Dkk-3. Addition of hrDkk-3 peptide (1 or 10 ng/ml) to HUVECs for 6 or 12 h enhanced the intracellular and extracellular VEGF protein levels, as assessed by RTPCR, immunoblotting, immunocytochemistry and ELISA. The increase in the extracellular VEGF levels was associated to the VEGFR2 activation. Pharmacological blockade of VEGFR2 abrogated Dkk-3-induced endothelial cell tubes formation, indicating that VEGF is a molecular player of the angiogenic effects of Dkk-3. Moreover, Dkk-3 enhanced Smad1/5/8 phosphorylation and recruited Smad4 to the VEGF gene promoter, suggesting that Dkk-3 activated ALK1 receptor leading to a transcriptional activation of VEGF. This mechanism was instrumental to the increased VEGF expression and endothelial cell tubes formation mediated by Dkk-3, because both effects were abolished by siRNA-mediated ALK1 knockdown. In summary, we have found that Dkk-3 activates ALK1 to stimulate VEGF production and induce angiogenesis in HUVECs. [ABSTRACT FROM AUTHOR]

Pulmonary fibrosis is a difficult to treat, often fatal disease whose pathogenesis involves dysregulated TGF-b1 signaling. CD4+CD25+FoxP3+ Regulatory T cells (Tregs) exert important effects on host tolerance and arise from naïve CD4+ lymphocytes in response to TGF-b1. However the precise contribution of Tregs to experimentally induced murine lung fibrosis remains unclear. We sought to better understand the role of Tregs in this context. Using a model of fibrosis caused by lung specific inducible overexpression of the bioactive form of the human TGF-b1 gene we find that Tregs accumulate in the lung parenchyma within five days of transgene activation and that this enhancement persists to at least fourteen days. Anti-CD25 Antibody mediated depletion of Tregs causes increased detection of soluble collagen and of intrapulmonary CD45+CD34+Col Ia1 fibrocytes. These findings are accompanied by enhanced local concentrations of the classical inflammatory mediators CD40L, TNF-a, and IL-1a, along with the neuroimmune molecule fibroblast growth factor 9 (FGF-9, also known as glial activating factor). FGF-9 expression localizes to structural cells and alveolar macrophages in this model and antibody mediated neutralization of FGF-9 results in attenuated detection of intrapulmonary collagen and fibrocytes without affecting Treg quantities. These data indicate that CD4+CD25+FoxP3+ Tregs attenuate TGF-b1 induced lung fibrosis and fibrocyte accumulation in part via suppression of FGF-9.