Antiplatelet drugs and liver fibrosis

The Platelet-Specific Gene Signature in the Immunoglobulin G4-Related Disease Transcriptome

Background and Objectives: Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated, fibroinflammatory, multiorgan disease with an obscure pathogenesis. Findings indicating excessive platelet activation have been reported in systemic sclerosis, which is another autoimmune, multisystemic fibrotic disorder. The immune-mediated, inflammatory, and fibrosing intersections of IgG4-RD and systemic sclerosis raised a question about platelets' role in IgG4-RD. Materials and Methods: By borrowing transcriptomic data from Nakajima et al. (GEO repository, GSE66465) we sought a platelet contribution to the pathogenesis of IgG4-RD. GEO2R and BRB-ArrayTools were used for class comparisons, and WebGestalt for functional enrichment analysis. During the selection of differentially expressed genes (DEGs), the translationally active but significantly low amount of platelet mRNA was specifically considered. The platelet-specific gene signature derived was used for cluster analysis of patient and control groups. Results: When IgG4-RD patients were compared with controls, 268 DEGs (204 with increased and 64 with decreased expression) were detected. Among these, a molecular signature of 22 platelet-specific genes harbored genes important for leukocyte-platelet aggregate formation (i.e., CLEC1B, GP1BA, ITGA2B, ITGB3, SELP, and TREML1) and extracellular matrix synthesis (i.e., CLU, PF4, PPBP, SPARC, and THBS1). Functional enrichment analysis documented significantly enriched terms related to platelets, including but not limited to "platelet reactivity", "platelet degranulation", "platelet aggregation", and "platelet activation". During clustering, the 22 gene signatures successfully discriminated IgG4-RD and the control and the IgG4-RD before and after treatment groups. Conclusions: Patients with IgG4-RD apparently display an activated platelet phenotype with a potential contribution to disease immunopathogenesis. If the platelets' role is validated through further carefully designed research, the therapeutic potentials of selected conventional and/or novel antiplatelet agents remain to be evaluated in patients with IgG4-RD. Transcriptomics and/or proteomics research with platelets should take into account the relatively low amounts of platelet mRNA, miRNA, and protein. Secondary analysis of omics data sets has great potential to reveal new and valuable information.

Clopidogrel ameliorates high-fat diet-induced hepatic steatosis in mice through activation of the AMPK signaling pathway and beyond

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) frequently confers an increased risk of vascular thrombosis; however, the marketed antiplatelet drugs are investigated for the prevention and treatment of MASLD in patients with these coexisting diseases.

Methods

To determine whether clopidogrel could ameliorate high-fat diet (HFD)-induced hepatic steatosis in mice and how it works, mice were fed on normal diet or HFD alone or in combination with or without clopidogrel for 14 weeks, and primary mouse hepatocytes were treated with palmitate/oleate alone or in combination with the compounds examined for 24 h. Body weight, liver weight, insulin resistance, triglyceride and total cholesterol content in serum and liver, histological morphology, transcriptomic analysis of mouse liver, and multiple key MASLD-associated genes and proteins were measured, respectively.

Results and discussion

Clopidogrel mitigated HFD-induced hepatic steatosis (as measured with oil red O staining and triglyceride kit assay) and reduced elevations in serum aminotransferases, liver weight, and the ratio of liver to body weight. Clopidogrel downregulated the expression of multiple critical lipogenic (Acaca/Acacb, Fasn, Scd1, Elovl6, Mogat1, Pparg, Cd36, and Fabp4), profibrotic (Col1a1, Col1a2, Col3a1, Col4a1, Acta2, and Mmp2), and proinflammatory (Ccl2, Cxcl2, Cxcl10, Il1a, Tlr4, and Nlrp3) genes, and enhanced phosphorylation of AMPK and ACC. However, compound C (an AMPK inhibitor) reversed enhanced phosphorylation of AMPK and ACC in clopidogrel-treated primary mouse hepatocytes and alleviated accumulation of intracellular lipids. We concluded that clopidogrel may prevent and/or reverse HFD-induced hepatic steatosis in mice, suggesting that clopidogrel could be repurposed to fight fatty liver in patients.

Fibroblasts and platelets: a face-to-face dialogue at the heart of cardiac fibrosis

Myocardial fibrosis is a feature found in most cardiac diseases and a key element contributing to heart failure and its progression. It has therefore become a subject of particular interest in cardiac research. Mechanisms leading to pathological cardiac remodeling and heart failure are diverse, including effects on cardiac fibroblasts, the main players in cardiac extracellular matrix synthesis, but also on cardiomyocytes, immune cells, endothelial cells, and more recently, platelets. Although transforming growth factor-β (TGF-β) is a primary regulator of fibrosis development, the cellular and molecular mechanisms that trigger its activation after cardiac injury remain poorly understood. Different types of anti-TGF-β drugs have been tested for the treatment of cardiac fibrosis and have been associated with side effects. Therefore, a better understanding of these mechanisms is of great clinical relevance and could allow us to identify new therapeutic targets. Interestingly, it has been shown that platelets infiltrate the myocardium at an early stage after cardiac injury, producing large amounts of cytokines and growth factors. These molecules can directly or indirectly regulate cells involved in the fibrotic response, including cardiac fibroblasts and immune cells. In particular, platelets are known to be a major source of TGF-β1. In this review, we have provided an overview of the classical cellular effectors involved in the pathogenesis of cardiac fibrosis, focusing on the emergent role of platelets, while discussing opportunities for novel therapeutic interventions.

Effects of thrombopoietin pre-treatment on peri-liver transplantation thrombocytopenia in a mouse model of cirrhosis with hypersplenism

BACKGROUND

During cirrhosis, the liver is impaired and unable to synthesize and clear thrombopoietin properly. At the same time, the spleen assumes the function of hemofiltration and storage due to liver dysfunction, resulting in hypersplenism and excessive removal of platelets in the spleen, further reducing platelet count. When liver function is decompensated in cirrhotic patients, the decrease of thrombopoietin (TPO) synthesis is the main reason for the decrease of new platelet production. This change of TPO leads to thrombocytopenia and bleeding tendency in cirrhotic patients with hypersplenism.

AIM

To investigate the clinical efficacy of recombinant human TPO (rhTPO) in the treatment of perioperative thrombocytopenia during liver transplantation in cirrhotic mice with hypersplenism.

METHODS

C57BL/6J mice and TPO receptor-deficient mice were used to establish models of cirrhosis with hypersplenism. Subsequently, these mice underwent orthotopic liver transplantation (OLT). The mice in the experimental group were given rhTPO treatment for 3 consecutive days before surgery and 5 consecutive days after surgery, while the mice in the control group received the same dose of saline at the same frequency. Differences in liver function and platelet counts were determined between the experimental and control groups. Enzyme-linked immunosorbent assay was used to assess the expression of TPO and TPO receptor (c-Mpl) in the blood.

RESULTS

Preoperative administration of rhTPO significantly improved peri-OLT thrombocytopenia in mice with cirrhosis and hypersplenism. Blocking the expression of TPO receptors exacerbated peri-OLT thrombocytopenia. The concentration of TPO decreased while the concentration of c-Mpl increased in compensation in the mouse model of cirrhosis with hypersplenism. TPO pre-treatment significantly increased the postoperative TPO concentration in mice, which in turn led to a decrease in the c-Mpl concentration. TPO pre-treatment also significantly enhanced the Janus kinase (Jak)/signal transducers and activators of transcription pathway protein expressions in bone marrow stem cells of the C57BL/6J mice. Moreover, the administration of TPO, both before and after surgery, regulated the levels of biochemical indicators, such as alanine aminotransferase, alkaline phosphatase, and aspartate aminotransferase in the C57BL/6J mice.

CONCLUSION

Pre-treatment with TPO not only exhibited therapeutic effects on perioperative thrombocytopenia in the mice with cirrhosis and hypersplenism, who underwent liver transplantation but also significantly enhanced the perioperative liver function.

Impact of concomitant cardiovascular medications on overall survival in patients with liver cirrhosis

OBJECTIVES OF THE ARTICLE

Liver cirrhosis is the end-stage liver disease associated with poor prognosis and cardiovascular comorbidity could significantly impact mortality of cirrhotic patients. We conducted a large, retrospective study to investigate the survival impact of cardiovascular co-medications in patients with liver cirrhosis.

MATERIALS AND METHODS

A study-specific R package was processed on the local databases of partner institutions within the Observational Health Data Sciences and Informatics consortium, namely Columbia University, New York City (NYC), USA and Ajou University School of Medicine (AUSOM), South Korea. Patients with cirrhosis diagnosed between 2000 and 2020 were included. Final analysis of the anonymous survival data was performed at Medical Faculty Mannheim, Heidelberg University.

RESULTS

We investigated a total of 32,366 patients with liver cirrhosis. Our data showed that administration of antiarrhythmics amiodarone or digoxin presented as a negative prognostic indicator (p = 0.000 in both cohorts). Improved survival was associated with angiotensin-converting enzyme inhibitor ramipril (p = 0.005 in NYC cohort, p = 0.075 in AUSOM cohort) and angiotensin II receptor blocker losartan (p = 0.000 in NYC cohort, p = 0.005 in AUSOM cohort). Non-selective beta blocker carvedilol was associated with a survival advantage in the NYC (p = 0.000) cohort but not in the AUSOM cohort (p = 0.142). Patients who took platelet inhibitor clopidogrel had a prolonged overall survival compared to those without (p = 0.000 in NYC cohort, p = 0.003 in AUSOM cohort).

CONCLUSION

Concomitant cardiovascular medications are associated with distinct survival difference in cirrhotic patients. Multidisciplinary management is needed for a judicious choice of proper cardiovascular co-medications in cirrhotic patients.

Microvascular Thrombosis and Liver Fibrosis Progression: Mechanisms and Clinical Applications

Fibrosis is an unavoidable consequence of chronic inflammation. Extracellular matrix deposition by fibroblasts, stimulated by multiple pathways, is the first step in the onset of chronic liver disease, and its propagation promotes liver dysfunction. At the same time, chronic liver disease is characterized by alterations in primary and secondary hemostasis but unlike previously thought, these changes are not associated with an increased risk of bleeding complications. In recent years, the role of coagulation imbalance has been postulated as one of the main mechanisms promoting hepatic fibrogenesis. In this review, we aim to investigate the function of microvascular thrombosis in the progression of liver disease and highlight the molecular and cellular networks linking hemostasis to fibrosis in this context. We analyze the predictive and prognostic role of coagulation products as biomarkers of liver decompensation (ascites, variceal hemorrhage, and hepatic encephalopathy) and liver-related mortality. Finally, we evaluate the current evidence on the application of antiplatelet and anticoagulant therapies for prophylaxis of hepatic decompensation or prevention of the progression of liver fibrosis.

The Important Roles of Natural Killer Cells in Liver Fibrosis

Liver fibrosis accompanies the development of various chronic liver diseases and promotes their progression. It is characterized by the abnormal accumulation of extracellular matrix proteins (ECM) and impaired ECM degradation. Activated hepatic stellate cells (HSCs) are the major cellular source of ECM-producing myofibroblasts. If liver fibrosis is uncontrolled, it may lead to cirrhosis and even liver cancer, primarily hepatocellular carcinoma (HCC). Natural killer (NK) cells are a key component of innate immunity and have miscellaneous roles in liver health and disease. Accumulating evidence shows that NK cells play dual roles in the development and progression of liver fibrosis, including profibrotic and anti-fibrotic functions. Regulating NK cells can suppress the activation of HSCs and improve their cytotoxicity against activated HSCs or myofibroblasts to reverse liver fibrosis. Cells such as regulatory T cells (Tregs) and molecules such as prostaglandin E receptor 3 (EP₃) can regulate the cytotoxic function of NK cells. In addition, treatments such as alcohol dehydrogenase 3 (ADH3) inhibitors, microRNAs, natural killer group 2, member D (NKG2D) activators, and natural products can enhance NK cell function to inhibit liver fibrosis. In this review, we summarized the cellular and molecular factors that affect the interaction of NK cells with HSCs, as well as the treatments that regulate NK cell function against liver fibrosis. Despite a lot of information about NK cells and their interaction with HSCs, our current knowledge is still insufficient to explain the complex crosstalk between these cells and hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, B cells, and T cells, as well as thrombocytes, regarding the development and progression of liver fibrosis.

Computational drug repositioning of clopidogrel as a novel therapeutic option for focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerular lesion often associated with nephrotic syndrome. It is also associated with a high risk of progression to end-stage kidney disease. Current treatment of FSGS is limited to systemic corticosteroids or calcineurin inhibition, along with inhibitors of the renin-angiotensin-aldosterone system. FSGS is heterogeneous in etiology, and novel therapies targeting specific, dysregulated molecular pathways represent a major unmet medical need. We have generated a network-based molecular model of FSGS pathophysiology using previously established systems biology workflows to allow computational evaluation of compounds for their predicted interference with molecular processes contributing to FSGS. We identified the anti-platelet drug clopidogrel as a therapeutic option to counterbalance dysregulated FSGS pathways. This prediction of our computational screen was validated by testing clopidogrel in the adriamycin FSGS mouse model. Clopidogrel improved key FSGS outcome parameters and significantly reduced urinary albumin to creatinine ratio (p<0.01) and weight loss (p<0.01), and ameliorated histopathological damage (p<0.05). Clopidogrel is used to treat several cardiovascular diseases linked to chronic kidney disease. Clopidogrel's favorable safety profile and its efficacy in the adriamycin mouse FSGS model thus recommend it as an attractive drug repositioning candidate for clinical trial in FSGS.

The Therapeutic Potential of Anticoagulation in Organ Fibrosis

Fibrosis, also known as organ scarring, describes a pathological stiffening of organs or tissues caused by increased synthesis of extracellular matrix (ECM) components. In the past decades, mounting evidence has accumulated showing that the coagulation cascade is directly associated with fibrotic development. Recent findings suggest that, under inflammatory conditions, various cell types (e.g., immune cells) participate in the coagulation process causing pathological outcomes, including fibrosis. These findings highlighted the potential of anticoagulation therapy as a strategy in organ fibrosis. Indeed, preclinical and clinical studies demonstrated that the inhibition of blood coagulation is a potential intervention for the treatment of fibrosis across all major organs (e.g., lung, liver, heart, and kidney). In this review, we aim to summarize our current knowledge on the impact of components of coagulation cascade on fibrosis of various organs and provide an update on the current development of anticoagulation therapy for fibrosis.

Nonalcoholic fatty liver disease and cardiovascular concerns: The time for hepatologist and cardiologist close collaboration

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver cell damage worldwide. It is strongly associated with an increased risk of cardiovascular disease (CVD). There are not enough recommendations for screening subjects with nonalcoholic steatohepatitis cirrhosis, who are not candidates for liver transplantation, nor who are asymptomatic with NAFLD without cirrhosis. In the current comprehensive narrative review, we aimed to evaluate the associations between CVD and NAFLD. Distinguishing the mechanisms linking these two disorders offers the opportunity to develop targeted therapies. Moreover, we will discuss screening approaches (whom and how-to) and treatment modalities proposed to reduce cardiovascular risk in patients with NAFLD.