Effect of simvastatin on expression of transforming growth factor-β and collagen type IV in rat mesangial cells

Fibrosis of the diabetic heart: Clinical significance, molecular mechanisms, and therapeutic opportunities

In patients with diabetes, myocardial fibrosis may contribute to the pathogenesis of heart failure and arrhythmogenesis, increasing ventricular stiffness and delaying conduction. Diabetic myocardial fibrosis involves effects of hyperglycemia, lipotoxicity and insulin resistance on cardiac fibroblasts, directly resulting in increased matrix secretion, and activation of paracrine signaling in cardiomyocytes, immune and vascular cells, that release fibroblast-activating mediators. Neurohumoral pathways, cytokines, growth factors, oxidative stress, advanced glycation end-products (AGEs), and matricellular proteins have been implicated in diabetic fibrosis; however, the molecular links between the metabolic perturbations and activation of a fibrogenic program remain poorly understood. Although existing therapies using glucose- and lipid-lowering agents and neurohumoral inhibition may act in part by attenuating myocardial collagen deposition, specific therapies targeting the fibrotic response are lacking. This review manuscript discusses the clinical significance, molecular mechanisms and cell biology of diabetic cardiac fibrosis and proposes therapeutic targets that may attenuate the fibrotic response, preventing heart failure progression.

Immunomodulatory effect of statins on Regulatory T Lymphocytes in human colorectal cancer is determined by the stage of disease

Colorectal cancer (CRC) is a public health problem worldwide and in Jordan. Statins are cholesterol lowering agents. Beyond their effects, statins use has been reported to reduced risk of several malignances, including CRC. This study aimed to assess the effect of statins on CRC by studying cellular infiltration of Regulatory T Lymphocytes (Tregs) into CRC tissues and their effect on Transforming growth factor beta 1 (TGF-β₁) level and on angiogenesis. Fourty seven specimens (25 statins users vs. 22 non-users) were used. Immunohistochemistry was performed to study Tregs infiltration using their marker, fork head transcription factor, and angiogenesis using CD31 as a marker. TGF-β₁ levels were measured using ELISA. Results revealed that statins use was associated with more Tregs infiltration, less angiogenesis but no difference in TGF-β₁ content in tumor tissue. When results were further stratified according to stage of disease, more Tregs infiltration was significantly noticed in advanced disease but not in early disease. In addition, more angiogenesis inhibition was noticed in early disease but not in advanced disease. Same stage-dependence wasn’t noticed with TGF-β₁ expression. In early disease, reduction of angiogenesis mediated by statins might lead to reduction of tumor aggressiveness. On the other hand, Tregs infiltration into tumor mediated by statins might reduce cancer aggressiveness in advanced disease. These results suggest that statins might be used in the treatment of CRC.

Pharmacological regulation of SPARC by lovastatin in human trabecular meshwork cells

PURPOSE

Statins have been shown to increase aqueous outflow facility. The matricellular protein SPARC (secreted protein acidic and rich in cysteine) is a critical mediator of aqueous outflow and intraocular pressure (IOP). Here, we examine the effects of lovastatin on SPARC expression in trabecular meshwork (TM) cells, exploring the molecular mechanisms involved.

METHODS

Primary cultured human TM cells were incubated for 24, 48, and 72 hours with 10 μM lovastatin. In separate cultures, media was supplemented with either farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) for the duration of the 72-hour time point experiment. Trabecular meshwork cells were also pretreated for 24 hours with lovastatin followed by 24-hour stimulation with 3 ng/mL TGF-β2. Cell lysates and media were harvested and relative mRNA and protein level changes were determined. Krüppel-like factor 4 (KLF4) localization in normal human anterior segments was examined by immunofluorescence. Adenovirus expressing human KLF4 was used and relative changes in SPARC mRNA and protein levels were assessed.

RESULTS

Incubating TM cells with lovastatin suppressed SPARC mRNA and protein levels. This effect was reversed upon media supplementation with GGPP but not FPP. Pretreating cells with lovastatin inhibited TGF-β2 induction of SPARC. The KLF4 transcription factor was expressed throughout the TM and the inner and outer walls of Schlemm's canal. Lovastatin treatment upregulated KLF4 mRNA and protein levels. Overexpression of KLF4 downregulated SPARC expression.

CONCLUSIONS

Collectively, our data identify lovastatin as an important pharmacological suppressor of SPARC expression in TM cells, and provide further insight into the molecular mechanisms mediating statin enhancement of aqueous outflow facility.