A red wine polyphenolic extract reduces the activation phenotype of cultured human liver myofibroblasts

Activation of AMP-activated Protein Kinase by Metformin Inhibits Dedifferentiation of Platelet-derived Growth Factor-BB-induced Vascular Smooth Muscle Cells to Improve Arterial Remodeling in Cirrhotic Portal Hypertension

BACKGROUND & AIMS

Portal hypertension (PHT) is the potentially deadly complication of liver cirrhosis. Intrahepatic vascular resistance and the splanchnic hyperdynamic circulation are 2 principal driving factors contributing to the maintenance and exacerbation of PHT. However, in the advanced stages of cirrhosis, the fibrotic process in the liver becomes irreversible, leading to persistent and intractable increases in intrahepatic vascular resistance. Arterial remodeling emerges as a crucial mechanism driving the hyperdynamic splanchnic circulation. Therefore, ameliorating the hyperdynamic splanchnic circulation has become an indispensable component of PHT therapeutic strategies.

METHODS

Liver cirrhosis with PHT was induced in the rats by common bile duct ligation (BDL). Based on the transcriptomic sequencing of the mesenteric arteries, we investigated the effects and mechanisms of metformin on the arterial remodeling at different stages of cirrhosis. We further validated potential molecular mechanisms through in vitro experiments using the A7r5 smooth muscle cell line and primary vascular smooth muscle cells (VSMCs).

RESULTS

Our findings revealed the beneficial effects of metformin on liver cirrhosis and PHT in rats following BDL for 4 and 6 weeks. Metformin was observed to ameliorate PHT and splanchnic hyperdynamic circulation in BDL rats, even in the advanced stages of liver cirrhosis. This effect was evidenced by reduced portal pressure and cardiac output, decreased superior mesenteric artery (SMA) flow, accompanied by improvements in systemic vascular resistance and SMA resistance. Moreover, chronic inflammation in BDL rats was alleviated by metformin, which might inhibit the driving factors of angiogenesis and arterial remodeling. Notably, SMA dilation and arterial remodeling in BDL rats were potent alleviated following metformin treatment. Metformin ameliorated arterial remodeling in BDL rats by inhibiting the dedifferentiation of contractile VSMCs, resulting in the upregulation of contractile protein expressions such as alpha-smooth muscle actin (α-SMA) and smooth muscle 22α (SM22α). Platelet-derived growth factor-BB (PDGF-BB)/platelet-derived growth factor receptor beta (PDGFR-β) signaling exerted crucial roles in regulating the VSMCs cell phenotype. Activation of AMP-activated protein kinase (AMPK) by metformin blocked the downstream pathway of PDGF-BB/PDGFRβ. Furthermore, in vitro cell experiments, VSMCs were respectively treated with AMPK activator metformin or AMPK inhibitor Compound C. We revealed the molecular mechanism that metformin inhibited the phenotypic switching of A7r5 cells induced by PDGF-BB and primary VSMCs from BDL rats, which was mediated by activating AMPK to enhance the expression of contractile protein α-SMA. These findings suggest that AMPK can ameliorate the progression of arterial remodeling during PHT via suppressing the PDGF-BB/PDGFRβ signaling pathway, thereby offering novel insights into seek PHT treatment approaches.

CONCLUSIONS

Our findings revealed that metformin exerts its effects by activating the AMPK pathway, inhibiting the dedifferentiation of contractile VSMCs in the splanchnic arteries, and improving arterial remodeling, thereby ameliorating PHT and splanchnic hyperdynamic circulation in cirrhotic rats.

Flavonone treatment reverses airway inflammation and remodelling in an asthma murine model

BACKGROUND AND PURPOSE

Asthma is an inflammatory disease that involves airway hyperresponsiveness and remodelling. Flavonoids have been associated to anti-inflammatory and antioxidant activities and may represent a potential therapeutic treatment of asthma. Our aim was to evaluate the effects of the sakuranetin treatment in several aspects of experimental asthma model in mice.

EXPERIMENTAL APPROACH

Male BALB/c mice received ovalbumin (i.p.) on days 0 and 14, and were challenged with aerolized ovalbumin 1% on days 24, 26 and 28. Ovalbumin-sensitized animals received vehicle (saline and dimethyl sulfoxide, DMSO), sakuranetin (20 mg kg(-1) per mice) or dexamethasone (5 mg kg(-1) per mice) daily beginning from 24th to 29th day. Control group received saline inhalation and nasal drop vehicle. On day 29, we determined the airway hyperresponsiveness, inflammation and remodelling as well as specific IgE antibody. RANTES, IL-5, IL-4, Eotaxin, IL-10, TNF-α, IFN-γ and GMC-SF content in lung homogenate was performed by Bioplex assay, and 8-isoprostane and NF-kB activations were visualized in inflammatory cells by immunohistochemistry.

KEY RESULTS

We have demonstrated that sakuranetin treatment attenuated airway hyperresponsiveness, inflammation and remodelling; and these effects could be attributed to Th2 pro-inflammatory cytokines and oxidative stress reduction as well as control of NF-kB activation.

CONCLUSIONS AND IMPLICATIONS

These results highlighted the importance of counteracting oxidative stress by flavonoids in this asthma model and suggest sakuranetin as a potential candidate for studies of treatment of asthma.

Isolation and culture of fibroblasts from endoscopic duodenal biopsies of celiac patients

BACKGROUND

Fibroblasts are actually considered pivotal in inflammation and tissue remodelling process and for these reasons they are involved in the pathogenesis of autoimmune disorders such as celiac disease. Investigations to define the role of fibroblasts in celiac diseases are obstructed by the absence of specific models. Our objective is to isolate and culture primary fibroblasts from endoscopic duodenal biopsies of celiac and non-celiac subjects, to analyze their growth patterns and the morphometric characteristics.

METHODS

60 duodenal bioptic specimens from 20 celiac patients and 114 from 38 non-celiac subjects were mechanically chopped and enzymatically digested in order to obtain primary cell cultures. Growth patterns, karyotype (Q-banding analysis), expression of typing proteins (fibroblast surface protein and cytokeratin 20) and morphometric parameters (diameters and their ratio, perimeter, area and perimeter/area ratio at computerised image analysis) were investigated on cultured cells.

RESULTS

Primary cells were successfully cultured in 78% of the collected duodenal biopsies. Cultured cells, expressing the fibroblast surface protein, were negative for cytokeratine 20 and maintained a normal kariotype. Cells grew slowly without differences between the celiac and the non celiac group. Morphometric analysis of celiac fibroblasts revealed significantly increased dimensions, with a preserved diameters ratio, and a reduced perimeter/area ratio.

CONCLUSION

For the first time this study demonstrates the feasibility of culturing primary fibroblast cell from endoscopic duodenal biopsies in celiac and non-celiac subjects, opening a new window of opportunity in studies intended to establish the role of fibroblasts as a possible partaker in the pathogenesis of the celiac mucosal damage.