PM2.5 promotes Drp1-mediated mitophagy to induce hepatic stellate cell activation and hepatic fibrosis via regulating miR-411.

BACKGROUND: Particulate matter≤ 2.5 µm (PM2.5) is a type of environmental agent associated with air pollution, which induces hepatic fibrosis. However, the function and mechanism of PM2.5 on hepatic stellate cell (HSC) proliferation and fibrosis remain largely unknown. METHODS: Human HSC line (LX-2) and murine HSCs were exposed to various doses of PM2.5. microRNA (miR)-411 expression was detected via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell proliferation, fibrosis, mitochondrial dynamics dysfunction and mitophagy were determined via cell counting kit-8 (CCK-8), qRT-PCR, Western blotting and immunofluorescence. RESULTS: PM2.5 facilitated HSC proliferation and fibrosis via increasing the levels of ACTA2, Collagen 1, TIMP1 and TGF-ß1. PM2.5 reduced miR-411 expression, and contributed to mitochondrial dynamics dysfunction via increasing Drp1 and decreasing OPA1, TOM20 and PGC-1α levels. PM2.5 promoted mitophagy by upregulating the levels of Beclin-1, LC3II/I, PINK1 and Parkin. miR-411 overexpression or autophagy blockage using 3-methyladenine (3-MA) relieved PM2.5-mediated cell proliferation and fibrosis-associated factor expression in HSCs. Drp1 was targeted by miR-411. miR-411 mitigated PM2.5-induced mitophagy via targeting Drp1. Drp1 overexpression abolished the inhibitory role of miR-411 in cell proliferation and fibrosis-associated factor levels in HSCs. CONCLUSION: PM2.5 induced HSC activation and fibrosis via promoting Drp1-mediated mitophagy by decreasing miR-411, thereby causing liver fibrosis.

PM2.5 induces liver fibrosis via triggering ROS-mediated mitophagy.

BACKGROUND: The increasing epidemic of fine particulate matter (PM2.5) is a serious threat to human health. It induces the occurrence of liver fibrosis, but its molecular mechanism is not yet clear. The molecular mechanisms of PM2.5 inducing liver fibrosis were investigated in this study. METHODS: The cell viability of LX-2 cells and primary hepatic stellate cells (HSCs) was detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In vitro enzyme-linked immune sorbent assay (ELISA) kits were used to detect the concentrations of antioxidant enzymes and reactive oxygen species (ROS). The mitochondrial transmembrane potential (MTP) was determined by JC-1 dye. Knockdown of Parkin was carried out by Parkin-specific siRNA transfection. Relative mRNA and protein expressions were evaluated by qRT-PCR, Western blotting, and immunofluorescence analysis. RESULTS: PM2.5 activated LX-2 cells and primary HSCs, inducing the liver fibrosis along with down-regulation of the gelatinases MMP-2, and up-regulation of myofibroblast markers collagen type I and α-SMA. The levels of ROS and reactive nitrogen species (RNS), as well as the lipid peroxidation marker malondialdehyde (MDA) were significantly up-regulated in LX-2 cells and primary HSCs treated with PM2.5. Also, the enzymatic antioxidants levels were disturbed by PM2.5. Furthermore, PM2.5 decreased the MTP, releasing cytochrome c from the mitochondria to the cytosol. The dynamics of mitochondria were regulated by PM2.5 via facilitating mitochondrial fission. The excess ROS induced by PM2.5 triggered the mitophagy by activating PINK1/Parkin pathway, and inhibition of mitophagy induced by PM2.5 diminished the liver fibrosis. CONCLUSION: PM2.5 may induce mitophagy via activating PINK1/Parking signal pathway by increasing ROS, thereby activating HSCs and causing liver fibrosis.

[Comparisons of clinical features of chronic aplastic anemia and myelodysplastic syndrome in children].

OBJECTIVE: This study compared the differences in clinical features between chronic aplastic anemia (CAA) and myelodysplastic syndrome (MDS) in children in order to provide a basis for the differential diagnosis of the two diseases. METHODS: A retrospective study of 23 cases of CAA and 9 cases of MDS from September 2007 to September 2010 was performed. The clinical data including routine blood test results, reticulocyte counts, serum lactate dehydrogenase level, serum ferritin level, cytological examination of bone marrow, bone marrow CD34+ cell counts, bone marrow chromosome and FISH test results were compared between the CAA and MDS groups. RESULTS: Neutrophils, reticulocytes, and serum ferritin and lactate dehydrogenase levels increased in the MDS group compared with those in the CAA group. There were significant differences in bone marrow blast cell counts and dyshematopoiesis phenomena of three lines blood cells between the CAA and MDS groups. The bone marrow CD34+ cell counts and the rate of chromosomal abnormalities detected in bone marrow cytogenetic analysis in the MDS group were significantly higher than those in the CAA group. CONCLUSIONS: There are differences in the results of laboratory examinations and morphological and cytogenetic examinations of bone marrow between the children with CAA and MDS. The differences are useful to the differential diagnosis of the two diseases.