Metformin ameliorates liver fibrosis induced by congestive hepatopathy via the mTOR/HIF-1α signaling pathway

HIF-1α/LTBP2 axis activate HSCs to promote liver fibrosis by interacting with LOXL1 via the ERK pathway

Latent Transforming Growth Factor Beta Binding Protein 2 (LTBP2) is a multi-domain exocrine protein located in the extracellular matrix (ECM) and has been implicated in fibrosis across various organs. However, its role in liver fibrosis remains inadequately understood. This study aims to elucidate the function and mechanism of LTBP2 in hepatic stellate cells (HSCs) activation and liver fibrosis. Our findings indicate that LTBP2 expression is positively correlated with liver fibrosis and is significantly elevated in fibrotic liver tissues from both human and murine models. Importantly, AAV6-mediated knockdown of LTBP2 in HSCs markedly alleviates CCl4-induced liver fibrosis by inhibiting the HSCs activation and reducing collagen deposition in mice. Gain-of-function and loss-of-function experiments confirmed that overexpression or knockdown of LTBP2 can enhance or inhibit the activation of HSCs, proliferation, migration and epithelial-mesenchymal transition (EMT) in LX-2 cells. Mechanistically, chromatin immunoprecipitation (ChIP) assays and dual-luciferase reporter gene assays revealed that Hypoxia-inducible Factor 1α (HIF-1α) promotes LTBP2 expression by directly binding to the LTBP2 promoter region. Furthermore, molecular docking and co-immunoprecipitation (Co-IP) experiments demonstrated an interaction between Lysyl Oxidase Like Protein 1 (LOXL1) and LTBP2. Rescue experiments verified that LTBP2 interacts with LOXL1 via the ERK signaling pathway to promote the activation of HSCs and EMT. Our results provide compelling evidence that the HIF-1α/LTBP2 axis facilitates the activation of HSCs and EMT by interacting with LOXL1 through ERK signaling pathway, suggesting that LTBP2 may serve as a potential therapeutic target for liver fibrosis.

Metformin in Antiviral Therapy: Evidence and Perspectives

Metformin, a widely used antidiabetic medication, has emerged as a promising broad-spectrum antiviral agent due to its ability to modulate cellular pathways essential for viral replication. By activating AMPK, metformin depletes cellular energy reserves that viruses rely on, effectively limiting the replication of pathogens such as influenza, HIV, SARS-CoV-2, HBV, and HCV. Its role in inhibiting the mTOR pathway, crucial for viral protein synthesis and reactivation, is particularly significant in managing infections caused by HIV, CMV, and EBV. Furthermore, metformin reduces oxidative stress and reactive oxygen species (ROS), which are critical for replicating arboviruses such as Zika and dengue. The drug also regulates immune responses, cellular differentiation, and inflammation, disrupting the life cycle of HPV and potentially other viruses. These diverse mechanisms suppress viral replication, enhance immune system functionality, and contribute to better clinical outcomes. This multifaceted approach highlights metformin's potential as an adjunctive therapy in treating a wide range of viral infections.

Enhanced Ferritin‐Manganese Interaction by Nanoplatinum Growth Enabling Liver Fibrosis 3D Magnetic Resonance Visualization and Synergistic Therapy with Real‐Time Monitoring

Early detection and timely intervention are essential to prevent liver fibrosis from progressing to cirrhosis or hepatocellular carcinoma. Herein, utilizing the enhanced ferritin‐manganese interaction by nanoplatinum growth, a novel ferritin‐platinum‐manganese magnetic resonance nanoplatform with RGD grafting and metformin loading (FNMMR) is developed. RGD can enhance the targeting ability of the nanoplatform toward integrin αVβ3 on activated hepatic stellate cells (aHSCs) in liver fibrosis. Systemic delivery of FNMMR shows clear degree‐dependent magnetic resonance contrast enhancement in liver fibrosis. 3D reconstruction techniques and histogram‐based features are achieved to qualitatively and quantitatively analyze the inhomogeneous liver fibrosis areas. FNMMR with catalase‐like activity can catalyze the generation of O2 to alleviate the liver fibrosis hypoxia and inhibit the expression of HIF‐1α, blocking the TGF‐β1/Smad signaling pathway. In addition, metformin shows synergy with HIF‐1α reduction in blocking the TGF‐β1/Smad pathway, effectively inhibiting the activation of HSCs and reducing collagen formation. Furthermore, FNMMR can achieve real‐time anti‐fibrotic therapy monitoring by magnetic resonance imaging. Importantly, no obvious side effects can be observed in both histological and hematology examinations. Therefore, this work presents a novel nanoplatform for accurate liver fibrosis diagnosis and synergistic anti‐fibrotic therapy with real‐time monitoring.

TGF-β1 Signaling Impairs Metformin Action on Glycemic Control

Hyperglycemia is a hallmark of type 2 diabetes (T2D). Metformin, the first-line drug used to treat T2D, maintains blood glucose within a normal range by suppressing hepatic glucose production (HGP). However, resistance to metformin treatment is developed in most T2D patients over time. Transforming growth factor beta 1 (TGF-β1) levels are elevated both in the liver and serum of T2D humans and mice. Here, we found that TGF-β1 treatment impairs metformin action on suppressing HGP via inhibiting AMPK phosphorylation at Threonine 172 (T172). Hepatic TGF-β1 deficiency improves metformin action on glycemic control in high fat diet (HFD)-induced obese mice. In our hepatic insulin resistant mouse model (hepatic insulin receptor substrate 1 (IRS1) and IRS2 double knockout (DKO)), metformin action on glycemic control was impaired, which is largely improved by further deletion of hepatic TGF-β1 (TKObeta1) or hepatic Foxo1 (TKOfoxo1). Moreover, blockade of TGF-β1 signaling by chemical inhibitor of TGF-β1 type I receptor LY2157299 improves to metformin sensitivity in mice. Taken together, our current study suggests that hepatic TGF-β1 signaling impairs metformin action on glycemic control, and suppression of TGF-β1 signaling could serve as part of combination therapy with metformin for T2D treatment.