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. 2015 Mar 30;10(3):e0121939.
doi: 10.1371/journal.pone.0121939. eCollection 2015.

Pyrroloquinoline-quinone suppresses liver fibrogenesis in mice

Dongwei Jia  1 , Fangfang Duan  2 , Peike Peng  1 , Linlin Sun  1 , Yuanyuan Ruan  1 , Jianxin Gu  3
Affiliations

Pyrroloquinoline-quinone suppresses liver fibrogenesis in mice

Dongwei Jia et al. PLoS One. .

Abstract

Liver fibrosis represents the consequences of a sustained wound healing response to chronic liver injuries, and its progression toward cirrhosis is the major cause of liver-related morbidity and mortality worldwide. However, anti-fibrotic treatment remains an unconquered area for drug development. Accumulating evidence indicate that oxidative stress plays a critical role in liver fibrogenesis. In this study, we found that PQQ, a natural anti-oxidant present in a wide variety of human foods, exerted potent anti-fibrotic and ROS-scavenging activity in Balb/C mouse models of liver fibrosis. The antioxidant activity of PQQ was involved in the modulation of multiple steps during liver fibrogenesis, including chronic liver injury, hepatic inflammation, as well as activation of hepatic stellate cells and production of extracellular matrix. PQQ also suppressed the up-regulation of RACK1 in activated HSCs in vivo and in vitro. Our data suggest that PQQ suppresses oxidative stress and liver fibrogenesis in mice, and provide rationale for the clinical application of PQQ in the prevention and treatment of liver fibrosis.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. PQQ protects mice from TAA-induced liver fibrosis.
(A) Liver sections from TAA-treated mice were stained with HE, α-SMA antibody and Sirius red. Closed arrowhead indicates inflammatory cells infiltration; Open arrowhead indicates fibrotic septa; asterisk indicates hydropic degeneration (top panel). Scale bar, 100 μm. (B) Quantitative analysis of Sirius red-positive area by IPP software. (C) Expression of α-SMA and collagen 1A1 in liver tissues was determined by western blot to evaluate the level of HSCs transdifferentiation and collagen 1A1 production. (D) Quantification of hydroxyproline content in liver tissues. N, normal group. M, TAA model. L, low-dose PQQ. H, high-dose PQQ. S, silymarin. In (B) and (D), n = 8 in each group. **, p<0.01.
Fig 2
Fig 2. PQQ ameliorates the redox status in livers of TAA-treated mice.
(A-B) Frozen liver sections were stained with DHE (A), and average fluorescence unit was calculated by Leica software (B). In (A), scale bar = 100 μm. (C) Total hepatic cells were harvested, stained with DHE, and analyzed by flow cytometry. (D) Total hepatic cells were harvested and stained with CellROX as well as primary antibodies. Primary hepatocytes (albumin+), HSCs (α-SMA+) and macrophages (F4/80+) were gated and analyzed by flow cytometry. (E) The activities of GSH-Px, CAT and SOD in liver tissues were measured. (F) Primary hepatocytes, HSCs and macrophages from TAA-treated mice were treated with PQQ for 30 min, and activities of GSH-Px, CAT and SOD were measured. N, normal group. M, TAA model. L, low-dose PQQ. H, high-dose PQQ. S, silymarin. In (A-E), n = 8 in each group. *, p<0.05; **, p<0.01.
Fig 3
Fig 3. PQQ suppresses TAA-induced hepatocyte death and chronic liver injury in mice.
(A) Liver tissues were collected at 4 weeks after TAA treatment. Cryosections were fixed with cold acetone, blocked with donkey serum and stained with antibodies specific for albumin (red) and cleaved caspase 3 (green). The images are representative photomicrographs of each group. Scale bar, 100 μm. (B) Hepatocytes were isolated from TAA-treated mice and stained with SYTOX, followed by flow cytometry analysis. (C) Serum levels of ALT, AST, and albumin in each group were measured. N, normal group. M, TAA model. L, low-dose PQQ. H, high-dose PQQ. S, silymarin. In (B) and (C), n = 8 in each group. **, p<0.01.
Fig 4
Fig 4. PQQ suppresses cytokine production and hepatic macrophage infiltration in fibrotic liver.
(A) Total RNA was extracted from liver tissues at indicated days after TAA treatment, and mRNA levels of cytokines in each group were detected by qPCR. (B-D) Liver sections were stained with antibodies against F4/80 (green) and CD68 (red). F4/80 positive area and merge area were measured by IPP software. Scale bar, 100 μm. N, normal control group. M, TAA model. L, low-dose PQQ. H, high-dose PQQ. S, silymarin. In (A, C and D), n = 8 in each group. *, p<0.05, **, p<0.01.
Fig 5
Fig 5. PQQ inhibits cytokine-induced activation, proliferation and migration of HSCs.
Primary mouse HSCs were treated with TGF-β1 or PDGF, along with or without increasing doses of PQQ or NAC. (A, B) The level of intracellular ROS was measured by DCFH-DA staining and flow cytometry analysis. (C) Protein expression of α-SMA and collagen 1A1 in HSCs were examined by western blot analysis to evaluate the level of HSCs transdifferentiation and collagen 1A1 production after 24 h treatment of TGF-β1. (D) Primary HSCs were applied to CCK8 assay. (E, F) Primary HSCs were applied to transwell assay. *, p<0.05, **, p<0.01.
Fig 6
Fig 6. PQQ suppresses RACK1 expression in activated HSCs by inhibiting NF-κB pathway.
(A) Liver sections were stained with RACK1 (red) and α-SMA (green) antibodies. Scale bar, 100 μm. (B) Freshly isolated HSCs from different groups of mice were applied to western-blot and qPCR analysis to detect RACK1 expression. (C, D) Primary mouse HSCs were treated with 10 ng/ml TGF-β1 for 24 h, along with or without increasing doses of PQQ or NAC. Total cell lysates or nuclear extracts were subjected to western blot analysis (C) and ChIP assay (D). N, normal group. M, TAA model. L, low-dose PQQ. H, high-dose PQQ. S, silymarin. *, p<0.05, **, p<0.01.
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References

    1. Friedman S. Liver fibrosis? from bench to bedside. Journal of Hepatology. 2003;38:38–53. - PubMed
    1. Sanchez-Valle V, Chavez-Tapia NC, Uribe M, Mendez-Sanchez N. Role of oxidative stress and molecular changes in liver fibrosis: a review. Curr Med Chem. 2012;19(28):4850–60. - PubMed
    1. Bataller R, Brenner DA. Liver fibrosis. J Clin Invest. 2005;115(2):209–18. - PMC - PubMed
    1. Zhang DY, Friedman SL. Fibrosis-dependent mechanisms of hepatocarcinogenesis. Hepatology. 2012;56(2):769–75. 10.1002/hep.25670 - DOI - PMC - PubMed
    1. Ellis EL, Mann DA. Clinical evidence for the regression of liver fibrosis. J Hepatol. 2012;56(5):1171–80. 10.1016/j.jhep.2011.09.024 - DOI - PubMed

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