PT  - JOURNAL ARTICLE
AU  - Zhenglin Zhu
AU  - Shengqiang Gao
AU  - Hui Zhu
AU  - Yi Chen
AU  - Dandong Wu
AU  - Zhiyu Chen
AU  - Jing Zou
AU  - Xiangdong Wu
AU  - Ning Hu
AU  - Wei Huang
AU  - Hong Chen
TI  - Metformin Alleviates Arthrofibrosis in Rat via Fibroblast Metabolic Reprogramming and Lactate-Mediated Macrophage Polarization
AID  - 10.1101/2022.07.05.498844
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.07.05.498844
4099  - http://biorxiv.org/content/early/2022/07/05/2022.07.05.498844.short
4100  - http://biorxiv.org/content/early/2022/07/05/2022.07.05.498844.full
AB  - Background Emerging studies have suggested an essential role of fibroblast metabolic reprogramming in the pathogenesis of arthrofibrosis. The metabolic modulator metformin appears to be a good candidate for fibrotic disorder treatment. We sought to determine the beneficial effect of metformin on arthrofibrosis and the underlying mechanism of action of this drug.Methods Shoulder capsule samples were collected from patients with/without frozen shoulder to perform gene and protein expression analysis. Arthrofibrotic animal model was established to examine the anti-fibrotic effect of metformin. In vitro cell culture experiments were conducted to determine the mechanism by which metformin inhibits fibroblast activation.Results Clinical sample analysis demonstrated that glycolysis was upregulated in human fibrotic joint capsules. In an arthrofibrotic animal model, metformin improved the joint range of motion, reduced capsular fibrosis and thickening, mitigated inflammatory reactions, and downregulated both fibrotic and glycolytic markers. The results of gene and protein expression analysis showed that metformin effectively inhibited TGF-β induced fibroblast activation. The metabolomics study confirmed a metformin-induced metabolic shift from oxidative phosphorylation (OXPHOS) to aerobic glycolysis in fibroblasts. Importantly, the inhibitory effect of metformin on fibroblast activation was mediated by metabolic reprogramming of fibroblasts. Interestingly, fibroblast-derived lactate induced M2-like macrophage polarization and diminished the inflammatory reaction.Conclusions Metformin is a potential treatment alternative for arthrofibrosis, and antifibrotic effect of the drug involves metabolic reprogramming toward aerobic glycolysis in fibroblasts and lactate-induced M2-like macrophage polarization.Competing Interest StatementThe authors have no relevant financial or non-financial interests to disclose.AMPKAMP-activated protein kinaseANOVAAnalysis of varianceα-SMAα-Smooth muscle actinArg-1Arginase-1CCK-8Cell Counting Kit-8DAPI4’,6-diamidino-2-phenylindoleECMExtracellular matrixEDTAEthylenediaminetetraacetic acidFBSFetal bovine serum18FDG-PET18F-fluoro-deoxyglucose positron-emission tomographyFN1FibronectinGLUT1Glucose transporter 1HEHematoxylin-eosinHK2Hexokinase-2IFN-γInterferon-γIHCImmunohistochemistryILInterleukiniNOSInducible nitric oxide synthaseLC-MSLiquid Chromatograph-Mass SpectrometerLDHALactate dehydrogenaseMΦMacrophageNSAIDsNon-Steroidal Anti-Inflammatory DrugsOARSIOsteoarthritis Research Society InternationalODOptical densityOXPHOSOxidative phosphorylationPBSPhosphate buffered salinePFKFB36-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3PFKPPhosphofructokinasePLGAPoly (lactic-co-glycolic acid)PKMPyruvate kinase MqRT-PCRReverse transcription-quantitative polymerase chain reactionROMRange of motionSEMStandard error of meanTCATricarboxylic acidTGF-βTransforming growth factor-βTNF-αTumor necrosis factor-α