Genomic Surveillance for SARS-CoV-2 Variants: Dominance of XBB Replacement - China, January-June 2023.

Introduction: In the first half of 2023, a global shift was observed towards the predominance of XBB variants. China faced a significant epidemic between late 2022 and early 2023 due to Omicron subvariants BA.5.2 and BF.7. This study aims to depict the evolving variant distribution among provincial-level administrative divisions (PLADs) in China and explore the factors driving the predominance of XBB replacement. Methods: Sequences from local and imported coronavirus disease 2019 (COVID-19) cases recorded between January 1 and June 30, 2023, were included. The study analyzed the changing distribution of viral variants and assessed how the prior dominance of specific variants, XBB subvariants, and imported cases influenced the prevalence of the XBB replacement variant. Results: A total of 56,486 sequences were obtained from local cases, and 8,669 sequences were from imported cases. Starting in April, there was a shift in the prevalence of XBB from imported to local cases, with varying dominance among PLADs. In PLADs previously high in BF.7, the rise of XBB was delayed. A positive correlation was found between XBB proportions in imported cases from January to March and local cases in April. The distribution pattern of XBB subvariants differed between local and imported cases within the same PLAD. No significant differences were noted in the replacement rates of XBB subvariants. Conclusions: The timing of XBB dominance differed among various PLADs in China in the first half of 2023, correlating closely with the prevalence of XBB variants among imported cases.

Prevalence and diversity of imported severe acute respiratory syndrome coronavirus 2 variants in China, 2021-2022.

The causative agent of coronavirus disease 2019 (COVID-19), known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread accumulatively to 240 countries and continues to evolve. To gain a comprehensive understanding of the epidemiological characteristics of imported variants in China and their correlation with global circulating variants, genomic surveillance data from 11 139 imported COVID-19 cases submitted by Chinese provincial CDC laboratories between 2021 and 2022 were analyzed. Consensus sequences underwent rigorous quality checks, followed by amino acid mutations analysis using Nextclade. Sequences with satisfactory quality control status were classified according to the Pango nomenclature. The results showed that the dominant variants in imported cases reflected the global epidemic trend. An increase in the number of imported SARS-CoV-2 lineages monitored in China in the second half of 2022, and the circulating Omicron subvariants changed from the ancestral lineages of BA.5 and BA.2 into the lineages containing key amino acid mutations of spike protein. There was significant variation in the detection of Omicron subvariants among continents (χ2 = 321.968, p < 0.001) in the second half of 2022, with four lineages (BA.2.3.7, BA.2.2, BA.5.2.7, and XBB.1.2) identified through imported surveillance mainly prevalent respectively in Taiwan, China, Hong Kong SAR, China, Russian Federation, and Singapore. These findings revealed the alterations in circulating imported variants from 2021 to 2022 in China, reflecting the higher diversity of lineages in the second half of 2022, and revealed the predominant lineages of countries or regions that are in close contacts to China, providing new insights into the global prevalence of SARS-CoV-2.

Genomic Surveillance for SARS-CoV-2 - China, September 26, 2022 to January 29, 2023.

Introduction: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated 2,431 variants over the course of its global transmission over the past 3 years. To better evaluate the genomic variation of SARS-CoV-2 before and after the optimization of coronavirus disease 2019 (COVID-19) prevention and control strategies, we analyzed the genetic evolution branch composition and genomic variation of SARS-CoV-2 in both domestic and imported cases in China (the data from Hong Kong and Macau Special Administrative Regions and Taiwan, China were not included) from September 26, 2022 to January 29, 2023. Methods: Analysis of the number of genome sequences, sampling time, dynamic changes of evolutionary branches, origin, and clinical typing of SARS-CoV-2 variants submitted by 31 provincial-level administrative divisions (PLADs) and Xinjiang Production and Construction Corps (XPCC) was conducted to assess the accuracy and timeliness of SARS-CoV-2 variant surveillance. Results: From September 26, 2022 to January 29, 2023, 20,013 valid genome sequences of domestic cases were reported in China, with 72 evolutionary branches. Additionally, 1,978 valid genome sequences of imported cases were reported, with 169 evolutionary branches. The prevalence of the Omicron variants of SARS-CoV-2 in both domestic and imported cases was consistent with that of international epidemic variants. Conclusions: This study provides an overview of the prevalence of Omicron variants of SARS-CoV-2 in China. After optimizing COVID-19 prevention and control strategies, no novel Omicron variants of SARS-CoV-2 with altered biological characteristics or public health significance have been identified since December 1, 2022.

Genomic Surveillance for SARS-CoV-2 Variants of Concern from Imported COVID-19 Cases - the Mainland of China, 2021.

Introduction: After the epidemic in Wuhan City was brought under control in 2020, local outbreaks of coronavirus disease 2019 (COVID-19) in the mainland of China were mainly due to imported COVID-19 cases. The ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has continued to generate new variants. Some have been designated as variants of concern (VOCs) by the World Health Organization (WHO). To better assess the role of imported SARS-CoV-2 surveillance and the prevalence of VOCs in 2021, the genomic surveillance data of SARS-CoV-2 from imported COVID-19 cases of 2021 in the mainland of China were analyzed. Methods: The analyses included the number of sequence submissions, time of sequence deposition, and time of detection of the VOCs in order to determine the timeliness and sensitivity of the surveillance. The proportions of VOCs were analyzed and compared with data from the Global Initiative of Sharing All Influenza Data (GISAID). Results: A total of 3,355 sequences of imported cases were submitted from 29 provincial-level administrative divisions, with differences in the number of sequence submissions and median time of sequence deposition. A total of 2,388 sequences with more than 90% genomic coverage were used for lineage analysis. The epidemic trend from Alpha to Delta to Omicron in imported cases was consistent with that in the GISAID. In addition, VOCs from imported cases were usually identified after WHO designation and before causing local outbreaks. Conclusions: The global distribution of SARS-CoV-2 VOCs changed rapidly in 2021. Robust genomic surveillance of the imported SARS-CoV-2 in the mainland of China is of great significance.

IMM-H007 attenuates isoprenaline-induced cardiac fibrosis through targeting TGFß1 signaling pathway.

Upon chronic stress, ß-adrenergic receptor activation induces cardiac fibrosis and leads to heart failure. The small molecule compound IMM-H007 has demonstrated protective effects in cardiovascular diseases via activation of AMP-activated protein kinase (AMPK). This study aimed to investigate IMM-H007 effects on cardiac fibrosis induced by ß-adrenergic receptor activation. Because adenosine analogs also exert AMPK-independent effects, we assessed AMPK-dependent and -independent IMM-H007 effects in murine models of cardiac fibrosis. Continual subcutaneous injection of isoprenaline for 7 days caused cardiac fibrosis and cardiac dysfunction in mice in vivo. IMM-H007 attenuated isoprenaline-induced cardiac fibrosis, diastolic dysfunction, α-smooth muscle actin expression, and collagen I deposition in both wild-type and AMPKα2-/- mice. Moreover, IMM-H007 inhibited transforming growth factor ß1 (TGFß1) expression in wild-type, but not AMPKα2-/- mice. By contrast, IMM-H007 inhibited Smad2/3 signaling downstream of TGFß1 in both wild-type and AMPKα2-/- mice. Surface plasmon resonance and molecular docking experiments showed that IMM-H007 directly interacts with TGFß1, inhibits its binding to TGFß type II receptors, and downregulates the Smad2/3 signaling pathway downstream of TGFß1. These findings suggest that IMM-H007 inhibits isoprenaline-induced cardiac fibrosis via both AMPKα2-dependent and -independent mechanisms. IMM-H007 may be useful as a novel TGFß1 antagonist.

SARS-CoV-2 cold-chain transmission: Characteristics, risks, and strategies.

Low temperature and certain humidity are conducive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for long-time survival and long-distance spread during logistics and trades. Contaminated cold-chain or frozen products and outer packaging act as the carrier of SARS-CoV-2, that infects the high-risk population who works in the ports, cold storage or seafood market. Since the coronavirus disease 2019 (COVID-19) pandemic worldwide, multiple localized outbreaks caused by SARS-CoV-2 contaminated imported cold-chain products have been reported in China, which brought challenges to COVID-19 prevention and control. Here, we review the evidences of SARS-CoV-2 cold-chain transmission from six confirmed cold-chain related COVID-19 outbreaks in China, especially in terms of SARS-CoV-2 whole-genome sequencing and virus isolation. In addition, we summarize the characteristics and mode of SARS-CoV-2 cold-chain transmission from both six COVID-19 outbreaks in China and the outbreaks suspected cold-chain transmission in other countries. Finally, we analyze the underlying risks of SARS-CoV-2 cold-chain transmission and propose the preventive countermeasures.

Glibenclamide alleviates ß adrenergic receptor activation-induced cardiac inflammation.

ß-Adrenergic receptor (ß-AR) overactivation is a major pathological factor associated with cardiac diseases and mediates cardiac inflammatory injury. Glibenclamide has shown anti-inflammatory effects in previous research. However, it is unclear whether and how glibenclamide can alleviate cardiac inflammatory injury induced by ß-AR overactivation. In the present study, male C57BL/6J mice were treated with or without the ß-AR agonist isoprenaline (ISO) with or without glibenclamide pretreatment. The results indicated that glibenclamide alleviated ISO-induced macrophage infiltration in the heart, as determined by Mac-3 staining. Consistent with this finding, glibenclamide also inhibited ISO-induced chemokines and proinflammatory cytokines expression in the heart. Moreover, glibenclamide inhibited ISO-induced cardiac fibrosis and dysfunction in mice. To reveal the protective mechanism of glibenclamide, the NLRP3 inflammasome was further analysed. ISO activated the NLRP3 inflammasome in both cardiomyocytes and mouse hearts, but this effect was alleviated by glibenclamide pretreatment. Furthermore, in cardiomyocytes, ISO increased the efflux of potassium and the generation of ROS, which are recognized as activators of the NLRP3 inflammasome. The ISO-induced increases in these processes were inhibited by glibenclamide pretreatment. Moreover, glibenclamide inhibited the cAMP/PKA signalling pathway, which is downstream of ß-AR, by increasing phosphodiesterase activity in mouse hearts and cardiomyocytes. In conclusion, glibenclamide alleviates ß-AR overactivation-induced cardiac inflammation by inhibiting the NLRP3 inflammasome. The underlying mechanism involves glibenclamide-mediated suppression of potassium efflux and ROS generation by inhibiting the cAMP/PKA pathway.

Surveillance and Analysis of SARS-CoV-2 Variant Importation - China, January-June 2022.

Introduction: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is the dominant circulating strain worldwide. To assess the importation of SARS-CoV-2 variants in the mainland of China during the Omicron epidemic, the genomic surveillance data of SARS-CoV-2 from imported coronavirus disease 2019 (COVID-19) cases in the mainland of China during the first half of 2022 were analyzed. Methods: Sequences submitted from January to July 2022, with a collection date before June 30, 2022, were incorporated. The proportions of SARS-CoV-2 variants as well as the relationships between the origin and destination of each Omicron imported case were analyzed. Results: 4,946 sequences of imported cases were submitted from 27 provincial-level administrative divisions (PLADs), and the median submission interval was within 1 month after collection. In 3,851 Omicron sequences with good quality, 1 recombinant (XU) and 4 subvariants under monitoring (BA.4, BA.5, BA.2.12.1, and BA.2.13) were recorded, and 3 of them (BA.4, BA.5, and BA.2.12.1) caused local transmissions in the mainland of China later than that recorded in the surveillance. Omicron subvariants dominated in the first half of 2022 and shifted from BA.1 to BA.2 then to BA.4 and BA.5. The percentage of BA.2 in the imported SARS-CoV-2 surveillance data was far higher than that in the Global Initiative on Sharing All Influenza Data (GISAID). The imported cases from Hong Kong Special Administrative Region, China, accounted for 32.30% of Omicron cases sampled, and 98.71% of them were BA.2. Conclusions: The Omicron variant showed the intra-Omicron evolution in the first half of 2022, and all of the Omicron subvariants were introduced into the mainland of China multiple times from multiple different locations.

Membrane nanotubes facilitate the propagation of inflammatory injury in the heart upon overactivation of the ß-adrenergic receptor.

Acute sympathetic stress quickly induces cardiac inflammation and injury, suggesting that pathogenic signals rapidly spread among cardiac cells and that cell-to-cell communication may play an important role in the subsequent cardiac injury. However, the underlying mechanism of this response is unknown. Our previous study demonstrated that acute ß-adrenergic receptor (ß-AR) signaling activates inflammasomes in the heart, which triggers the inflammatory cascade. In the present study, ß-AR overactivation induced inflammasome activation in both the cardiomyocytes and cardiac fibroblasts (CFs) of mice hearts following a subcutaneous injection of isoproterenol (ISO, 5 mg/kg body weight), a selective agonist of ß-AR. In isolated cardiac cells, ISO treatment only activated the inflammasomes in the cardiomyocytes but not the CFs. These results demonstrated that inflammasome activation was propagated from cardiomyocytes to CFs in the mice hearts. Further investigation revealed that the inflammasomes were activated in the cocultured CFs that connected with cardiomyocytes via membrane nanotubes (MNTs), a novel membrane structure that mediates distant intercellular connections and communication. Disruption of the MNTs with the microfilament polymerization inhibitor cytochalasin D (Cyto D) attenuated the inflammasome activation in the cocultured CFs. In addition, the MNT-mediated inflammasome activation in the CFs was blocked by deficiency of the inflammasome component NOD-like receptor protein 3 (NLRP3) in the cardiomyocytes, but not NLRP3 deficiency in the CFs. Moreover, ISO induced pyroptosis in the CFs cocultured with cardiomyocytes, and this process was inhibited by disruption of the MNTs with Cyto D or by the NLRP3 inhibitor MCC950 and the caspase-1 inhibitor Z-YVAD-FMK (FMK). Our study revealed that MNTs facilitate the rapid propagation of inflammasome activation among cardiac cells to promote pyroptosis in the early phase of ß-adrenergic insult. Therefore, preventing inflammasome transfer is a potential therapeutic strategy to alleviate acute ß-AR overactivation-induced cardiac injury.

Paired box 6 inhibits cardiac fibroblast differentiation.

Cardiac fibroblast (CF) differentiation plays a crucial role in cardiac fibrosis, which is a specific manifestation distinguishing pathological cardiac hypertrophy from physiological hypertrophy. The DNA-binding activity of paired box 6 (Pax6) has been shown to be oppositely regulated in physiological and pathological hypertrophy; however, it remains unclear whether Pax6 is involved in CF differentiation during cardiac fibrosis. We found that Pax6 is expressed in the heart of and CFs isolated from adult mice. Moreover, angiotensin II (Ang II) induced the downregulation of Pax6 mRNA and protein expression in fibrotic heart tissue and cardiac myofibroblasts. Pax6 knockdown in CFs promoted the expression of the myofibroblast marker α-smooth muscle actin (α-SMA) and the synthesis of the extracellular matrix (ECM) proteins collagen I and fibronectin. Furthermore, we validated the ability of Pax6 to bind to the promoter regions of Cxcl10 and Il1r2 and the intronic region of Tgfb1. Pax6 knockdown in CFs decreased CXC chemokine 10 (CXCL10) and interleukin-1 receptor 2 (IL-1R2) expression and increased transforming growth factor ß1 (TGFß1) expression, mimicking the effects of Ang II. In conclusion, Pax6 exerts an inhibitory effect on CF differentiation and ECM synthesis by transcriptionally activating the expression of the anti-fibrotic factors CXCL10 and IL-1R2 and repressing the expression of the pro-fibrotic factor TGFß1. Therefore, maintaining Pax6 expression in CFs is essential for preventing CF differentiation, and provides a new therapeutic target for cardiac fibrosis.

α1-AR overactivation induces cardiac inflammation through NLRP3 inflammasome activation.

Acute sympathetic stress causes excessive secretion of catecholamines and induces cardiac injuries, which are mainly mediated by ß-adrenergic receptors (ß-ARs). However, α1-adrenergic receptors (α1-ARs) are also expressed in the heart and are activated upon acute sympathetic stress. In the present study, we investigated whether α1-AR activation induced cardiac inflammation and the underlying mechanisms. Male C57BL/6 mice were injected with a single dose of α1-AR agonist phenylephrine (PE, 5 or 10 mg/kg, s.c.) with or without pretreatment with α-AR antagonist prazosin (5 mg/kg, s.c.). PE injection caused cardiac dysfunction and cardiac inflammation, evidenced by the increased expression of inflammatory cytokine IL-6 and chemokines MCP-1 and MCP-5, as well as macrophage infiltration in myocardium. These effects were blocked by prazosin pretreatment. Furthermore, PE injection significantly increased the expression of NOD-like receptor protein 3 (NLRP3) and the cleavage of caspase-1 (p20) and interleukin-18 in the heart; similar results were observed in both Langendorff-perfused hearts and cultured cardiomyocytes following the treatment with PE (10 µM). Moreover, PE-induced NLRP3 inflammasome activation and cardiac inflammation was blocked in Nlrp3-/- mice compared with wild-type mice. In conclusion, α1-AR overactivation induces cardiac inflammation by activating NLRP3 inflammasomes.

[Research advances of autonomic nervous system in the regulation of cardiac inflammation].

The autonomic nervous system consists of the sympathetic nervous system and the parasympathetic nervous system. These two systems control the heart and work in a reciprocal fashion to modulate myocardial energy metabolism, heart rate as well as blood pressure. Multiple cardiac pathological conditions are accompanied by autonomic imbalance, characterized by sympathetic overactivation and parasympathetic inhibition. Studies have shown that overactive sympathetic nervous system leads to increased cardiac inflammatory reaction. Orchestrated inflammatory response serves to clear dead cardiac tissue and activate reparative process, whereas excessive inflammation may result in pathological cardiac remodeling. Since the discovery of the α7 nicotinic acetylcholine receptor (α7nAChR)-mediated cholinergic anti-inflammatory pathway (CAP), the protective effects of the parasympathetic nervous system in cardiac inflammation have attracted more attention recently. In this review, we summarized the role and underlying mechanisms of the sympathetic and parasympathetic nervous systems in cardiac inflammation, in order to provide new insight into cardiac inflammatory response in cardiovascular diseases.

ß3-adrenergic receptor activation induces TGFß1 expression in cardiomyocytes via the PKG/JNK/c-Jun pathway.

In heart failure, the expression of cardiac ß3-adrenergic receptors (ß3-ARs) increases. However, the precise role of ß3-AR signaling within cardiomyocytes remains unclear. Transforming growth factor ß1 (TGFß1) is a crucial cytokine mediating the cardiac remodeling that plays a causal role in the progression of heart failure. Here, we set out to determine the effect of ß3-AR activation on TGFß1 expression in rat cardiomyocytes and examine the underlying mechanism. The selective ß3-AR agonist BRL37344 induced an increase in TGFß1 expression and the phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun in ß3-AR-overexpressing cardiomyocytes. Those effects of BRL37344 were suppressed by a ß3-AR antagonist. Moreover, the inhibition of JNK and c-Jun activity by a JNK inhibitor and c-Jun siRNA blocked the increase in TGFß1 expression upon ß3-AR activation. A protein kinase G (PKG) inhibitor also attenuated ß3-AR-agonist-induced TGFß1 expression and the phosphorylation of JNK and c-Jun. In conclusion, the ß3-AR activation in cardiomyocytes increases the expression of TGFß1 via the PKG/JNK/c-Jun pathway. These results help us further understand the role of ß3-AR signaling in heart failure.

Metformin attenuates angiotensin II-induced TGFß1 expression by targeting hepatocyte nuclear factor-4-α.

BACKGROUND AND PURPOSE: Metformin, a small molecule, antihyperglycaemic agent, is a well-known activator of AMP-activated protein kinase (AMPK) and protects against cardiac fibrosis. However, the underlying mechanisms remain elusive. TGFß1 is a key cytokine mediating cardiac fibrosis. Here, we investigated the effects of metformin on TGFß1 production induced by angiotensin II (AngII) and the underlying mechanisms. EXPERIMENTAL APPROACH: Wild-type and AMPKα2-/- C57BL/6 mice were injected s.c. with metformin or saline and infused with AngII (3 mg·kg-1 ·day-1 ) for 7 days. Adult mouse cardiac fibroblasts (CFs) were isolated for in vitro experiments. KEY RESULTS: In CFs, metformin inhibited AngII-induced TGFß1 expression via AMPK activation. Analysis using bioinformatics predicted a potential hepatocyte nuclear factor 4α (HNF4α)-binding site in the promoter region of the Tgfb1 gene. Overexpressing HNF4α increased TGFß1 expression in CFs. HNF4α siRNA attenuated AngII-induced TGFß1 production and cardiac fibrosis in vitro and in vivo. Metformin inhibited the AngII-induced increases in HNF4α protein expression and binding to the Tgfb1 promoter in CFs. In vivo, metformin blocked the AngII-induced increase in cardiac HNF4α protein levels in wild-type mice but not in AMPKα2-/- mice. Consequently, metformin inhibited AngII-induced TGFß1 production and cardiac fibrosis in wild-type mice but not in AMPKα2-/- mice. CONCLUSIONS AND IMPLICATIONS: HNF4α mediates AngII-induced TGFß1 transcription and cardiac fibrosis. Metformin inhibits AngII-induced HNF4α expression via AMPK activation, thus decreasing TGFß1 transcription and cardiac fibrosis. These findings reveal a novel antifibrotic mechanism of action of metformin and identify HNF4α as a new potential therapeutic target for cardiac fibrosis. LINKED ARTICLES: This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

AMPK and cardiac remodelling.

Cardiac remodelling is generally accepted as a critical process in the progression of heart failure. Myocyte hypertrophy, inflammatory responses and cardiac fibrosis are the main pathological changes associated with cardiac remodelling. AMP-activated protein kinase (AMPK) is known as an energy sensor and a regulator of cardiac metabolism under normal and ischaemic conditions. Additionally, AMPK has been shown to play roles in cardiac remodelling extending well beyond metabolic regulation. In this review, we discuss the currently defined roles of AMPK in cardiac remodelling and summarize the effects of AMPK on cardiac hypertrophy, inflammatory responses and fibrosis and the molecular mechanisms underlying these effects. In addition, we discuss some pharmacological activators of AMPK that are promising treatments for cardiac remodelling.

Metformin attenuates renal fibrosis in both AMPKα2-dependent and independent manners.

Metformin is a well-known AMP-activated protein kinase (AMPK) activator, and it has been shown to inhibit organ fibrosis. Whether AMPKα2 mediates metformin protection against renal fibrosis remains unknown. Here, we aimed to investigate the role of the AMPKα2 isoform in mediating the inhibitory effect of metformin on renal fibrosis. Unilateral ureteral obstruction (UUO) was used to induce renal fibrosis in wild-type (WT) and AMPKα2 knockout (AMPKα2-/- ) mice. Metformin treatment was initiated 3 days before UUO and was continued until 7 days after UUO. In WT mice, metformin significantly inhibited UUO-induced renal fibrosis. In AMPKα2-/- mice, metformin also tended to inhibit UUO-induced renal fibrosis. Specifically, metformin significantly reduced UUO-induced transforming growth factor ß1 (TGFß1) mRNA and protein expression in WT mice but not in AMPKα2-/- mice. In contrast, metformin reduced UUO-induced TGFß1 downstream Smad3 phosphorylation in both WT and AMPKα2-/- mice, suggesting that this regulation occurs in an AMPKα2-independent manner. In conclusion, the underlying mechanisms for the protective effects of metformin against renal fibrosis include AMPKα2-dependent targeting of TGFß1 production and AMPKα2-independent targeting of TGFß1 downstream signalling. In this regard, metformin has an advantage over other AMPK activators for the treatment of renal fibrosis.

Metformin is a novel suppressor for transforming growth factor (TGF)-ß1.

Metformin is a widely used first-line antidiabetic drug that has been shown to protect against a variety of specific diseases in addition to diabetes, including cardiovascular disorders, polycystic ovary syndrome, and cancer. However, the precise mechanisms underlying the diverse therapeutic effects of metformin remain elusive. Here, we report that transforming growth factor-ß1 (TGF-ß1), which is involved in the pathogenesis of numerous diseases, is a novel target of metformin. Using a surface plasmon resonance-based assay, we identified the direct binding of metformin to TGF-ß1 and found that metformin inhibits [(125)I]-TGF-ß1 binding to its receptor. Furthermore, based on molecular docking and molecular dynamics simulations, metformin was predicted to interact with TGF-ß1 at its receptor-binding domain. Single-molecule force spectroscopy revealed that metformin reduces the binding probability but not the binding force of TGF-ß1 to its type II receptor. Consequently, metformin suppresses type II TGF-ß1 receptor dimerization upon exposure to TGF-ß1, which is essential for downstream signal transduction. Thus, our results indicate that metformin is a novel TGF-ß suppressor with therapeutic potential for numerous diseases in which TGF-ß1 hyperfunction is indicated.