Transforming growth factor-beta (TGF-beta) participates in the pathogenesis of multiple cardiovascular diseases, including hypertension, restenosis, atherosclerosis, cardiac hypertrophy and heart failure. TGF-beta exerts pleiotropic effects on cardiovascular cells, regulating cell growth, fibrosis and inflammation. TGF-beta has long been believed to be the most important extracellular matrix regulator. We review the complex mechanisms involved in TGF-beta-mediated vascular fibrosis that includes the Smad signaling pathway, activation of protein kinases and crosstalk between these pathways. TGF-beta blockade diminishes fibrosis in experimental models, however better antifibrotic targets are needed for an effective therapy in human fibrotic diseases. A good candidate is connective tissue growth factor (CTGF), a downstream mediator of TGF-beta-induced fibrosis. Among the different factors involved in vascular fibrosis, Angiotensin II (AngII) has special interest. AngII can activate the Smad pathway independent of TGF-beta and shares with TGF-beta many intracellular signals implicated in fibrosis. Blockers of AngII have demonstrated beneficial effects on many cardiovascular diseases and are now one of the best options to block TGF-beta fibrotic responses. A better knowledge of the intracellular signals of TGF-beta can provide novel therapeutic approaches for fibrotic diseases.

The pharmacological blockade of angiotensin II actions, by angiotensin-converting enzyme inhibitors or angiotensin receptor antagonists, results in beneficial organ protective effects, in addition to the effects of these agents on blood pressure control, that can be explained by the blockade of the angiotensin II-induced pro-inflammatory response. These data provide a rationale for the use of blockers of the renin-angiotensin system to prevent vascular and renal inflammation in patients with hypertension.

Connective tissue growth factor (CTGF) is an important profibrotic factor in kidney diseases. Blockade of endogenous CTGF ameliorates experimental renal damage and inhibits synthesis of extracellular matrix in cultured renal cells. CTGF regulates several cellular responses, including adhesion, migration, proliferation, and synthesis of proinflammatory factors. Here, we investigated whether CTGF participates in the inflammatory process in the kidney by evaluating the nuclear factor-kappa B (NF-B) pathway, a key signaling system that controls inflammation and immune responses. Systemic administration of CTGF to mice for 24 h induced marked infiltration of inflammatory cells in the renal interstitium (T lymphocytes and monocytes/macrophages) and led to elevated renal NF-B activity. Administration of CTGF increased renal expression of chemokines (MCP-1 and RANTES) and cytokines (INF-␥, IL-6, and IL-4) that recruit immune cells and promote inflammation. Treatment with a NF-B inhibitor, parthenolide, inhibited CTGF-induced renal inflammatory responses, including the up-regulation of chemokines and cytokines. In cultured murine tubuloepithelial cells, CTGF rapidly activated the NF-B pathway and the cascade of mitogen-activated protein kinases, demonstrating crosstalk between these signaling pathways. CTGF, via mitogen-activated protein kinase and NF-B activation, increased proinflammatory gene expression. These data show that in addition to its profibrotic properties, CTGF contributes to the recruitment of inflammatory cells in the kidney by activating the NF-B pathway.

Abstract-3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) reductase inhibitors (statins) present beneficial effects in cardiovascular diseases. Angiotensin II (Ang II) contributes to cardiovascular damage through the production of profibrotic factors, such as connective tissue growth factor (CTGF). Our aim was to investigate whether HMG-CoA reductase inhibitors could modulate Ang II responses, evaluating CTGF expression and the mechanisms underlying this process. In cultured vascular smooth muscle cells (VSMCs) atorvastatin and simvastatin inhibited Ang II-induced CTGF production. The inhibitory effect of statins on CTGF upregulation was reversed by mevalonate and geranylgeranylpyrophosphate, suggesting that RhoA inhibition could be involved in this process. In VSMCs, statins inhibited Ang II-induced Rho membrane localization and activation. In these cells Ang II regulated CTGF via RhoA/Rho kinase activation, as shown by inhibition of Rho with C3 exoenzyme, RhoA dominant-negative overexpression, and Rho kinase inhibition. Furthermore, activation of p38MAPK and JNK, and redox process were also involved in Ang II-mediated CTGF upregulation, and were downregulated by statins. In rats infused with Ang II (100 ng/kg per minute) for 2 weeks, treatment with atorvastatin (5 mg/kg per day) diminished aortic CTGF and Rho activation without blood pressure modification. Rho kinase inhibition decreased CTGF upregulation in rat aorta, mimicking statin effect. CTGF is a vascular fibrosis mediator. Angiotensin II (Ang II) participates in the pathogenesis of cardiovascular diseases. In hypertension, Ang II via AT 1 receptors induces vascular structural changes, including cell hypertrophy, accumulation of extracellular matrix (ECM) proteins, and induction of profibrotic growth factors, such as connective tissue growth factor (CTGF). 3 This growth factor also mediates cell proliferation/apoptosis, migration, cellular adhesion, wound healing, and angiogenesis. 4 CTGF overexpression has been found in human atherosclerotic and myocardial lesions as well as in the aorta of Ang II-infused rats, associated with ECM accumulation. [5][6][7] In VSMCs, CTGF acts as a downstream mediator of Ang II-induced fibrosis. 7 Received April 11, 2007; first decision April 29, 2007; In this study, we have investigated whether statins could directly modulate Ang II fibrotic responses in vascular tissue, studying the regulation of CTGF and the molecular mechanisms underlying this process, as the role of the activation of Rho/ROCK, MAPK, and redox process. MethodsThe materials and methods used in this study are described in the online supplement (available online at http://hyper.ahajournals.org). Results HMG-CoA Reductase Inhibitors Decrease CTGF Production Elicited by Ang II in Cultured VSMCsWe have previously demonstrated that in VSMCs Ang II upregulates CTGF. 7 VSMCs were pretreated for 1 hour with 2 statins: atorvastatin and simvastatin (10 Ϫ6 mol/L to 10 Ϫ9 mol/L). Both statins diminished CTGF production elicited by Ang II after 24 hours of inc...

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