Prolonged darkness reduces liver fibrosis in a mouse model of primary sclerosing cholangitis by miR‐200b down‐regulation

Abstract

Melatonin therapy or prolonged exposure to complete darkness reduces biliary hyperplasia and liver fibrosis in bile-duct-ligated (BDL) rats; however, no information exists in primary sclerosing cholangitis (PSC). Thus, we aimed to determine the therapeutic effects of prolonged dark therapy or melatonin administration on hepatic fibrosis in the multidrug resistance gene 2-knockout (Mdr2) mouse model of PSC. Melatonin levels, biliary mass, liver fibrosis, angiogenesis and miR-200b expression were evaluated in wild-type and Mdr2 mice exposed to darkness or melatonin treatment or in male patients with PSC and healthy controls. Mdr2 mice were also treated with miR-200b inhibitor or control before evaluating biliary mass, liver fibrosis, and angiogenesis. After overexpression of arylalkylamine -acetyltransferase (AANAT; the enzyme regulating melatonin synthesis) or inhibition of miR-200b in cholangiocytes and hepatic stellate cells, we evaluated angiogenesis and fibrosis gene expression. After exposure to darkness or administration of melatonin, Mdr2 mice show elevated serum melatonin levels and inhibition of biliary mass, along with reduction of liver fibrosis and angiogenesis. MicroRNA PCR analysis demonstrated that miR-200b expression increased in Mdr2 mice and patients with PSC compared with controls and decreased in Mdr2 mice subjected to dark exposure or melatonin treatment. Inhibition of miR-200b in Mdr2 ablates biliary proliferation, liver fibrosis, and angiogenesis. , overexpression of AANAT or inhibition of miR-200b in cholangiocytes and hepatic stellate cells decreased the expression of miR-200b, angiogenesis, and fibrosis genes. Dark therapy or targeting melatonin/miR-200b axis may be important in the management of biliary damage and liver fibrosis in cholangiopathies including PSC.-Wu, N., Meng, F., Zhou, T., Han, Y., Kennedy, L., Venter, J., Francis, H., DeMorrow, S., Onori, P., Invernizzi, P., Bernuzzi, F., Mancinelli, R., Gaudio, E., Franchitto, A., Glaser, S., Alpini G. Prolonged darkness reduces liver fibrosis in a mouse model of primary sclerosing cholangitis by miR-200b down-regulation.

Melatonin attenuates TNF‐α and IL‐1β expression in synovial fibroblasts and diminishes cartilage degradation: Implications for the treatment of rheumatoid arthritis

“…Several miRNAs are dysregulated during melatonin treatment for malignancies and hepatic disorders . Recently, Marques et al demonstrated that melatonin inhibits breast cancer progression by targeting miR‐152‐3p.…”

“…microRNAs (miRNAs), small noncoding RNAs that regulate protein production by controlling gene expression at the post‐transcriptional step, mediate the effects of melatonin in cancer and liver disease . In a recent study, miR‐590‐3p was found to mediate melatonin‐enhanced cell apoptosis in human osteoblasts .…”

Melatonin and circadian rhythms in liver diseases: Functional roles and potential therapies

“…Mdr2 −/− mice are the most common mouse model for human PSC, which have similar conditions such as cholestasis, biliary inflammation, ductular reaction, and liver fibrosis . Dark therapy (complete dark for 1 week) or melatonin administration (2 mg/g body weight per day for 1 week via drinking water) for Mdr2 −/− mice improved liver conditions compared to control Mdr2 −/− mice with 12:12 hours light‐dark cycle by inhibiting expression of VEGF‐A/C in cholangiocytes via decreased levels of microRNA (miRNA) miR‐200b . Thioacetamide (TAA) induces biliary damage in rodents and utilized as a model of cholestatic liver injury .…”

Interactions of Melatonin and MicroRNAs

“…Liver steatosis was reported to be ameliorated by melatonin via miR-23a [24]. In murine model of liver fibrosis, melatonin reduced primary sclerosing cholangitis by downregulating miR-200b in cholangiocytes and stellate cells [25]. Studies on miRNAs in Alzheimer's disease (AD) are of particular interest, because neuroinflammation, which is fueled by Aβ peptides and oligomers, can be partially reversed by melatonin [26].…”

“…In a rat scopolamine toxicity model of ADlike memory losses, melatonin reversed an increase of miR-124 and thereby corrected the level of the targeted Egr1 (early growth response protein 1) mRNA [27]. In another AD model, Aβ [25][26][27][28][29][30][31][32][33][34][35] peptide added to primary cortical neurons caused downregulation miR-132, an effect that was also reversed by melatonin. The normalization of miR-132 is insofar of importance, as this miRNA transmits anti-apoptotic and other protective properties known from melatonin [28].…”