TGFβ1 Induces Senescence and Attenuated VEGF Production in Retinal Pericytes

Diabetic retinopathy (DR) is a microvascular disease of the retina and a serious complication of type I and type II diabetes mellitus. DR affects working-age populations and can cause permanent vision loss if left untreated. The standard of care for proliferative DR is inhibiting VEGF. However, the mechanisms that induce excessive VEGF production in the retina remain elusive, although some evidence links elevated VEGF in the diabetic retina with local and systemic TGFβ1 upexpression. Here, we present evidence from animal models of disease suggesting that excessive TGFβ1 production in the early DR is correlated with VEGF mRNA and protein production by senescent pericytes and other retinal cells. Collectively, these results confirm that TGFβ1 is strongly implicated in the vascular complications of DR.

An RNA interference screen identifies new avenues for nephroprotection

This corrects the article DOI: 10.1038/cdd.2015.128.

Selective cathepsin S inhibition attenuates atherosclerosis in apolipoprotein E-deficient mice with chronic renal disease

Chronic renal disease (CRD) accelerates the development of atherosclerosis. The potent protease cathepsin S cleaves elastin and generates bioactive elastin peptides, thus promoting vascular inflammation and calcification. We hypothesized that selective cathepsin S inhibition attenuates atherogenesis in hypercholesterolemic mice with CRD. CRD was induced by 5/6 nephrectomy in high-fat high-cholesterol fed apolipoprotein E-deficient mice. CRD mice received a diet admixed with 6.6 or 60 mg/kg of the potent and selective cathepsin S inhibitor RO5444101 or a control diet. CRD mice had significantly higher plasma levels of osteopontin, osteocalcin, and osteoprotegerin (204%, 148%, and 55%, respectively; P < 0.05), which were inhibited by RO5444101 (60%, 40%, and 36%, respectively; P < 0.05). Near-infrared fluorescence molecular imaging revealed a significant reduction in cathepsin activity in treated mice. RO5444101 decreased osteogenic activity. Histologic assessment in atherosclerotic plaque demonstrated that RO5444101 reduced immunoreactive cathepsin S (P < 0.05), elastin degradation (P = 0.01), plaque size (P = 0.01), macrophage accumulation (P < 0.01), growth differentiation factor-15 (P = 0.0001), and calcification (alkaline phosphatase activity, P < 0.01; osteocalcin, P < 0.05). Furthermore, cathepsin S inhibitor or siRNA significantly decreased expression of growth differentiation factor-15 and monocyte chemotactic protein-1 in a murine macrophage cell line and human primary macrophages. Systemic inhibition of cathepsin S attenuates the progression of atherosclerotic lesions in 5/6 nephrectomized mice, serving as a potential treatment for atherosclerosis in patients with CRD.

A transgenic platform for testing drugs intended for reversal of cardiac remodeling identifies a novel 11βHSD1 inhibitor rescuing hypertrophy independently of re-vascularization

Rationale

Rescuing adverse myocardial remodeling is an unmet clinical goal and, correspondingly, pharmacological means for its intended reversal are urgently needed.

Objectives

To harness a newly-developed experimental model recapitulating progressive heart failure development for the discovery of new drugs capable of reversing adverse remodeling.

Methods and Results

A VEGF-based conditional transgenic system was employed in which an induced perfusion deficit and a resultant compromised cardiac function lead to progressive remodeling and eventually heart failure. Ability of candidate drugs administered at sequential remodeling stages to reverse hypertrophy, enlarged LV size and improve cardiac function was monitored. Arguing for clinical relevance of the experimental system, clinically-used drugs operating on the Renin-Angiotensin-Aldosterone-System (RAAS), namely, the ACE inhibitor Enalapril and the direct renin inhibitor Aliskerin fully reversed remodeling. Remodeling reversal by these drugs was not accompanied by neovascularization and reached a point-of-no-return. Similarly, the PPARγ agonist Pioglitazone was proven capable of reversing all aspects of cardiac remodeling without affecting the vasculature. Extending the arsenal of remodeling-reversing drugs to pathways other than RAAS, a specific inhibitor of 11β-hydroxy-steroid dehydrogenase type 1 (11β HSD1), a key enzyme required for generating active glucocorticoids, fully rescued myocardial hypertrophy. This was associated with mitigating the hypertrophy-associated gene signature, including reversing the myosin heavy chain isoform switch but in a pattern distinguishable from that associated with neovascularization-induced reversal.

Conclusions

A system was developed suitable for identifying novel remodeling-reversing drugs operating in different pathways and for gaining insights into their mechanisms of action, exemplified here by uncoupling their vascular affects.

Mast cell chymase inhibition reduces atherosclerotic plaque progression and improves plaque stability in ApoE-/- mice

AIMS

mast cells have been shown to accumulate in the adventitia of human atherosclerotic plaques and were recently demonstrated by us to contribute to plaque progression and instability. In this study, we investigated whether selective inhibition of mast cell chymases would affect the lesion development and stability.

METHODS AND RESULTS

the protease inhibitor RO5066852 appeared to be a potent inhibitor of chymase activity in vitro and ex vivo. With this inhibitor, we provide three lines of evidence that chymase inhibition can prevent many pro-atherogenic activities. First, oral administration of RO5066852 reduced spontaneous atherosclerosis in the thoracic aorta of apoE(-/-) mice. Second, chymase inhibition prevented the accelerated plaque progression observed in apoE(-/-) mice that were exposed to repetitive episodes of systemic mast cell activation. Furthermore, RO5066852 enhanced lesional collagen content and reduced necrotic core size. Third, RO5066852 treatment almost completely normalized the increased frequency and size of intraplaque haemorrhages observed in apoE(-/-) mice after acute perivascular mast cell activation in advanced atherosclerosis.

CONCLUSION

our data indicate that chymase inhibition can inhibit pro-atherogenic and plaque destabilizing effects which are associated with perivascular mast cell activation. Our study thus identifies pharmacological chymase inhibition as a potential therapeutic modality for atherosclerotic plaque stabilization.

Determination of extractability of pine bark using supercritical CO(2) extraction and different solvents: optimization and prediction

Bark from Pinus brutia was extracted with supercritical fluid extraction (SFE), using CO(2), at various extraction conditions both at laboratory and at pilot scale. Optimized parameters were 200 bar, 60 degrees C, and 3% ethanol at a solvent/feed ratio of 30. Additionally, the pine bark was sonicated (1 h at 50 degrees C) by different solvents (n-hexane, dichloromethane, ethyl acetate, and ethanol) to investigate the correlation between the different extraction setups and to obtain information on SFE up-scaling possibilities. Analyzed by HPLC, 7.2% of (-)-catechin was extractable at laboratory scale, and 58.4% (800 bar) and 47.8% (200 bar), both with modifiers, at pilot scale. By sonication with ethanol, 46.8% of (-)-catechin and almost 100% of (-)-epicatechin and (-)-catechin gallate were extracted. Ethyl acetate extract revealed high correlations with the laboratory scale SFE (r = 0.98) and also pilot scale SFE runs at 200 (r = 0.99) and 800 bar (r = 0.98) without modifiers.

EVI2B, a gene lying in an intron of the neurofibromatosis type 1 (NF1) gene, is as the NF1 gene involved in differentiation of melanocytes and keratinocytes and is overexpressed in cells derived from NF1 neurofibromas

The EVI2B gene is one of three genes embedded in intron 27b of the neurofibromatosis type 1 (NF1; M. Recklinghausen) gene, which are transcribed in the direction opposite that of the NF1 gene. The function of EVI2B and its relation to NF1 symptoms is unknown. Here, the amounts of NF1 and EVI2B mRNA were investigated in detail in cells involved in NF1 manifestations as café-au-lait macules and neurofibromas. These investigations showed that aside from the NF1 gene, EVI2B is involved in melanocyte and keratinocyte differentiation. Whereas in NF1 melanocytes from café-au-lait macules, EVI2B expression was not altered, in fibroblast-like cells derived from neurofibromas, an increased level of EVI2B mRNA was found. We investigated whether this increase was attributable to an influence of NF1 gene expression on the expression of the EVI2B gene, as suggested by the fact that the EVI2B primary transcript is antisense to the NF1 primary transcript. Investigations of cells derived from patients with different amounts of NF1 pre-mRNA showed no correlation between the amount of NF1 pre-mRNA and the increased level of EVI2B mRNA.