Novel functions of platelets in the liver

Per- and polyfluoroalkyl substances exposures are associated with non-alcoholic fatty liver disease, particularly fibrosis

Per- and polyfluoroalkyl substances (PFAS) have been reported to exert hepatotoxic effects; however, their impact on nonalcoholic fatty liver disease (NAFLD) remains unclear. This study aimed to investigate the association between PFAS exposure and NAFLD in Korean adults, thereby contributing to the generalization of PFAS's hepatotoxic effects. Using data from the 2018-2020 Korean National Environmental Health Survey (KoNEHS), we analyzed 2635 Korean adults. PFAS exposure levels were estimated based on the serum concentrations of five PFAS. NAFLD was assessed using two steatosis-related indices (hepatic steatosis index [HSI] and fatty liver index [FLI]) and two fibrosis-related indices (fibrosis-4 index [FIB-4] and aspartate aminotransferase to platelet ratio index [APRI]). The models included these indices as continuous and dichotomous variables, the latter based on diagnostic criteria from previous studies. Associations with PFAS exposure were examined using multiple linear regression and robust Poisson regression models. Positive associations were observed between PFAS exposure and three of the four continuous indices, excluding the FLI, as well as the prevalence of NAFLD diagnosed using these indices. Specifically, the HSI showed a significant association only with perfluorononanoic acid, whereas fibrosis-related indices (FIB-4 and APRI) were significantly associated with all five individual PFAS. The associations were stronger in female and non-obese groups when stratified by sex and obesity status. The results of the Bayesian kernel machine regression analysis evaluating the health effects of PFAS mixtures indicated an association between PFAS mixtures and NAFLD, particularly fibrosis-related indices. Additionally, significant associations with NAFLD indices were mostly observed in females and non-obese groups, supporting the findings from the individual PFAS exposure analyses. Our findings suggest that PFAS are associated with NAFLD, particularly for fibrosis. Considering the high serum PFAS concentrations in the Korean population, continuous monitoring and prospective cohort studies are warranted.

S, Bhola H. Spontaneous rectus sheath hematoma as a differential diagnosis for localized abdominal swelling in chronic liver disease: A rare case report

Key Clinical Message

Spontaneous rectus sheath hematoma is a rare complication in chronic liver disease patients. Early clinical suspicion with prompt radiological evaluation is crucial for accurate diagnosis and timely management.

Abstract

Spontaneous rectus sheath hematoma can present as an acute abdomen in the emergency department. The rupture of the upper and lower epigastric arteries and their branches is the main cause of hematoma formation. Hepatic dysfunction can affect the clotting process, increasing the risk of hematoma development. Computed tomography is the preferred diagnostic tool. Most hematomas can be managed conservatively, with only a few requiring minimal intervention or surgical management. We report an uncommon instance of spontaneous rectus sheath hematoma in a patient with chronic liver disease presenting with painful abdominal distention, mimicking a hernia and initially posing a diagnostic challenge. The rectus sheath hematoma was definitively diagnosed through clinical and radiological evaluation and subsequently evacuated with successful outcomes.

Assessing the Utility of the Aspartate Aminotransferase to Platelet Ratio Index (APRI) as a Noninvasive Indicator for Liver Cirrhosis

Background Of liver-related disorders, cirrhosis is currently the leading cause of death and has become a significant global public health concern. Aspartate aminotransferase to platelet ratio index (APRI), a newer prognostic modality, is a very effective noninvasive diagnostic for identifying advanced liver fibrosis. Methods A prospective observational study was conducted among individuals with liver disease, 100 cases and 100 controls for two years. All the sociodemographic details, clinical features of the patients, and clinical findings such as prothrombin time (PT), liver function tests, kidney function tests, and total blood count were recorded using a pretested semi-structured questionnaire. Results According to our survey results, 48% of the participants were between the ages of 40 and 60. Regarding aPTT (activated partial thromboplastin time) and liver function test characteristics (serum glutamic-oxaloacetic transaminase(SGOT), serum glutamic pyruvic transaminase (SGPT)), we showed a substantial difference between the patients and controls. Regarding the APRI distribution, we also found a statistically significant variation between the research groups. When we compared the validity of APRI scores in diagnosing cirrhosis, we discovered that the ideal cutoff value of APRI was determined to be 3.99, with sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 33%, 86%, 70%, and 56%, respectively. The area under the receiver operating characteristic (ROC) curve for APRI in detecting cirrhosis was also 0.693. Conclusion Thus, our study results conclude that APRI is a crucial noninvasive prognostic tool that can be utilized to prognostize liver cirrhosis.

Platelet lifespan and mechanisms for clearance

PURPOSE OF REVIEW

Activated or aged platelets are removed from circulation under (patho)physiologic conditions, the exact mechanism of platelet clearance under such conditions remains unclear and are currently being investigated. This review focuses on recent findings and controversies regarding platelet clearance and the disruption of platelet life cycle.

RECENT FINDINGS

The platelet life span is determined by glycosylation of platelet surface receptors with sialic acid. Recently, it was shown that platelet activation and granule release leads to desialylation of glycans and accelerated clearance of platelets under pathological conditions. This phenomenon was demonstrated to be a main reason for thrombocytopenia being a complication in several infections and immune disorders.

SUMMARY

Although we have recently gained some insight into how aged platelets are cleared from circulation, we are still not seeing the full picture. Further investigations of the platelet clearance pathways under pathophysiologic conditions are needed as well as studies to unravel the connection between platelet clearance and platelet production.

Platelets for advanced drug delivery in cancer

INTRODUCTION

Cancer-related drug expenses are rising with the increasing cancer incidence and cost may represent a severe challenge for drug access for patients with cancer. Consequently, strategies for increasing therapeutic efficacy of already available drugs may be essential for the future health-care system.

AREAS COVERED

In this review, we have investigated the potential for the use of platelets as drug-delivery systems. We searched PubMed and Google Scholar to identify relevant papers written in English and published up to January 2023. Papers were included at the authors' discretion to reflect an overview of state of the art.

EXPERT OPINION

It is known that cancer cells interact with platelets to gain functional advantages including immune evasion and metastasis development. This platelet-cancer interaction has been the inspiration for numerous platelet-based drug delivery systems using either drug-loaded or drug-bound platelets, or platelet membrane-containing hybrid vesicles combining platelet membranes with synthetic nanocarriers. Compared to treatment with free drug or synthetic drug vectors, these strategies may improve pharmacokinetics and selective cancer cell targeting. There are multiple studies showing improved therapeutic efficacy using animal models, however, no platelet-based drug delivery systems have been tested in humans, meaning the clinical relevance of this technology remains uncertain.

Clinical study on the evaluation of liver fibrosis by ultrasound elastography combined with platelet count model

OBJECTIVES

To establish the prediction model of liver fibrosis by combining ultrasound elastography and platelet count and evaluates its clinical value.

METHODS

146 patients with chronic liver diseases(CLD) admitted to our hospital from July 2020 to July 2022 were collected for liver biopsy pathological examination, and the results of ultrasound elastography (liver hardness value) and serological indicators were collected. Based on the results of Spearman correlation test and multiple linear regression model, the prediction model of liver fibrosis using ultrasound elastography combined with platelet count was constructed and verified.

RESULTS

The AUC of transient elastography combined with platelet count model (FSP) in the diagnosis of S2, S3 and S4 phases of liver fibrosis was 0.665, 0.835 and 0.909, with specificity of 81.5%, 90.0% and 100%. The AUC of sound touch elastography combined with platelet count model (STEP) in diagnosing S2, S3 and S4 phases of liver fibrosis was 0.685, 0.810 and 0884, with specificity of 96.3%, 90.0% and 83.3%, which are higher than APRI, FIB-4, FORNS, AAR and other models.

CONCLUSION

Ultrasound elastography combined with platelet count model has good diagnostic efficacy for liver fibrosis.

Advanced Endoscopic Resection Techniques in Cirrhosis-A Systematic Review and Meta-Analysis of Outcomes

BACKGROUND/AIMS

While safety and effectiveness of advanced endoscopic resection techniques such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) has been well established in general population, data regarding their utility in patients with cirrhosis is limited.

METHODS

We searched multiple databases from inception through July 2021 to identify studies that reported on outcomes of EMR and/or ESD in patients with cirrhosis. Meta-analysis was performed to determine pooled rates of immediate and delayed bleeding, perforation, death as well as rates of successful en bloc and R0 resection. Pooled relative risk (RR) was calculated for each outcome between patients with and without cirrhosis.

RESULTS

Ten studies with a total of 3244 patients were included in the final analysis. Pooled rates of immediate & delayed bleeding, perforation, and death during EMR and/or ESD in patients with cirrhosis were 9.5% (CI 4.0-21.1), 6.6% (CI 4.2-10.3), 2.1% (CI 1.1-3.9) and 0.6% (CI 0.2-1.7), respectively. Pooled rates of successful en bloc and R0 resection were 93% (CI 85.9-96.7) and 90.8% (CI 86.5-93.8), respectively. While incidence of immediate bleeding was higher in patients with cirrhosis, there was no statistically significant difference in any of the other outcomes between the patient groups.

CONCLUSIONS

Our study shows that performing EMR and ESD for gastrointestinal lesions in patients with cirrhosis is both safe and effective. The risks of procedural complications parallel those reported in general population.

Antiplatelet drugs and liver fibrosis

Liver fibrosis results from an imbalance between extracellular matrix formation and degradation. The background of liver fibrosis is chronic inflammation and subsequent microcirculation disturbance including microthrombosis. Platelets actively participate in liver fibrosis not only as a part of the clotting system but also by releasing granules containing important mediators. In fact, platelets may play a dual role in the pathophysiology of liver fibrosis as they are able to stimulate regeneration as well as aggravate the destruction of the liver. Recent studies revealed that antiplatelet therapy correlates with inhibition of liver fibrosis. However, liver impairment is associated with extensive coagulation disorders thus the safety of antiplatelet therapy is an area for detailed exploration. In this review, the role of platelets in liver fibrosis and accompanying hemostatic disorders are discussed. Additionally, results of animal and human studies on antiplatelet drugs in liver disorders and their potential therapeutic utility are presented.

Reenvisioning Traditional to Regenerative Therapeutic Advances in Managing Nonalcoholic Fatty Liver Disease in Diabetes Mellitus

Reports indicate the increasing prevalence of liver disorders in diabetes mellitus (DM) patients. Clinically, it has also been revealed that the existence of nonalcoholic fatty liver disease (NAFLD) enhances the incidence of type 2 diabetes mellitus (T2DM), while T2DM exacerbates NAFLD to extremely severe forms of steatohepatitis, cirrhosis, and hepatocellular carcinoma. This implies the coexistence and bidirectional nature of NAFLD and T2DM, which function synergistically to drive adverse consequences in clinical practice. For treatment of such comorbid state, though the existing practices such as lifestyle management, traditional Chinese medicines (TCM), and pharmaceuticals have offered somewhat relief, the debate continues about the optimal therapeutic impacts. Recent developments in the field of tissue engineering have led to a renewed interest in novel biomaterial alternatives such as stem cells. This might be attributable to their differentiation potential towards hepatic and pancreatic lineage. These cellular therapies could be further complemented by platelet-derived biomaterials, TCM formulations, or any specific drug. Based on these abovementioned approaches, we aimed to comprehensively analyze various preclinical and clinical studies from traditional to regenerative therapeutic approaches in managing concomitant NAFLD and T2DM.

Inflammatory and Non-Inflammatory Mechanisms Controlling Cirrhosis Development

Simple Summary

The liver is continuously exposed to several harmful factors, subsequently activating sophisticated mechanisms set-up in order to repair and regenerate the damaged liver and hence to prevent its failure. When the injury becomes chronic, the regenerative response becomes perpetual and goes awry, leading to cirrhosis with a fatal liver dysfunction. Cirrhosis is a well-known risk factor for hepatocellular carcinoma (HCC), the most common, usually lethal, human primary liver neoplasm with very limited therapeutic options. Considering the pivotal role of immune factors in the development of cirrhosis, here we review and discuss the inflammatory pathways and components implicated in the development of cirrhosis. A better understanding of these circuits would help the design of novel strategies to prevent and treat cirrhosis and HCC, two lethal diseases.

Abstract

Because the liver is considered to be one of the most important metabolic organs in the body, it is continuously exposed to damaging environmental agents. Upon damage, several complex cellular and molecular mechanisms in charge of liver recovery and regeneration are activated to prevent the failure of the organ. When liver injury becomes chronic, the regenerative response goes awry and impairs the liver function, consequently leading to cirrhosis, a liver disorder that can cause patient death. Cirrhosis has a disrupted liver architecture and zonation, along with the presence of fibrosis and parenchymal nodules, known as regenerative nodules (RNs). Inflammatory cues contribute to the cirrhotic process in response to chronic damaging agents. Cirrhosis can progress to HCC, the most common and one of the most lethal liver cancers with unmet medical needs. Considering the essential role of inflammatory pathways in the development of cirrhosis, further understanding of the relationship between immune cells and the activation of RNs and fibrosis would guide the design of innovative therapeutic strategies to ameliorate the survival of cirrhotic and HCC patients. In this review, we will summarize the inflammatory mechanisms implicated in the development of cirrhosis.

Extra- and Intra-Cellular Mechanisms of Hepatic Stellate Cell Activation

Hepatic fibrosis is characterized by the pathological accumulation of extracellular matrix (ECM) in the liver resulting from the persistent liver injury and wound-healing reaction induced by various insults. Although hepatic fibrosis is considered reversible after eliminating the cause of injury, chronic injury left unchecked can progress to cirrhosis and liver cancer. A better understanding of the cellular and molecular mechanisms controlling the fibrotic response is needed to develop novel clinical strategies. It is well documented that activated hepatic stellate cells (HSCs) is the most principal cellular players promoting synthesis and deposition of ECM components. In the current review, we discuss pathways of HSC activation, emphasizing emerging extra- and intra-cellular signals that drive this important cellular response to hepatic fibrosis. A number of cell types and external stimuli converge upon HSCs to promote their activation, including hepatocytes, liver sinusoidal endothelial cells, macrophages, cytokines, altered ECM, hepatitis viral infection, enteric dysbiosis, lipid metabolism disorder, exosomes, microRNAs, alcohol, drugs and parasites. We also discuss the emerging signaling pathways and intracellular events that individually or synergistically drive HSC activation, including TGFβ/Smad, Notch, Wnt/β-catenin, Hedgehog and Hippo signaling pathways. These findings will provide novel potential therapeutic targets to arrest or reverse fibrosis and cirrhosis.

Platelet Microparticles Decrease Daunorubicin-Induced DNA Damage and Modulate Intrinsic Apoptosis in THP-1 Cells

Platelets can modulate cancer through budding of platelet microparticles (PMPs) that can transfer a plethora of bioactive molecules to cancer cells upon internalization. In acute myelogenous leukemia (AML) this can induce chemoresistance, partially through a decrease in cell activity. Here we investigated if the internalization of PMPs protected the monocytic AML cell line, THP-1, from apoptosis by decreasing the initial cellular damage inflicted by treatment with daunorubicin, or via direct modulation of the apoptotic response. We examined whether PMPs could protect against apoptosis after treatment with a selection of inducers, primarily associated with either the intrinsic or the extrinsic apoptotic pathway, and protection was restricted to the agents targeting intrinsic apoptosis. Furthermore, levels of daunorubicin-induced DNA damage, assessed by measuring gH2AX, were reduced in both 2N and 4N cells after PMP co-incubation. Measuring different BCL2-family proteins before and after treatment with daunorubicin revealed that PMPs downregulated the pro-apoptotic PUMA protein. Thus, our findings indicated that PMPs may protect AML cells against apoptosis by reducing DNA damage both dependent and independent of cell cycle phase, and via direct modulation of the intrinsic apoptotic pathway by downregulating PUMA. These findings further support the clinical relevance of platelets and PMPs in AML.

Platelets level variability during the first year after liver transplantation in the risk prediction model for recipients mortality

INTRODUCTION AND OBJECTIVES

Many scoring systems in liver diseases use static values of liver function parameters. These parameters may change significantly in liver transplant (LTx) recipients over time due to various processes. The study was aimed at building a new model for survival prediction after LTx based on variability of selected parameters.

MATERIALS AND METHODS

The study included 450 LTx recipients who survived a minimum one year after transplantation. We analyzed liver enzymes and hematology parameters static values and their variability during the first year after transplantation. Modeling patients' survival was performed using Cox regression. Various sets of parameters (both static and variability and trends values) were tested to predict survival in our study group. Models' performance was measured using the concordance index.

RESULTS

The single predictors of the patients survival were the static values of AST with C-index 0.706 (0.5883-0.7494), ALT 0.6102 (0.4843-0.6857) and bilirubin 0.6224 (0.5537-0.6695). High prediction scores were observed for variability in creatinine 0.6023 (0.5409-0.6451), PLT 0.6350 (0.5491-0.7043), RBC 0.5689 (0.5065-0.6213) and WBC 0.6506 (0.5095-0.7124). Our best-fitted and proposed model for patients survival after LTx has C-index 0.8273 (IQR 0.7767-0.8649). The model uses the following indicators for mortality prediction: the static value of AST, variability measure of PLT and trend measures of WBC and PLT.

CONCLUSIONS

Adding variability and trend measures increases predictive accuracy in modeling patients survival after LTx. We propose a high-accuracy survival model in which variability and trend of PLT measures in the first year after transplantation are strong predictors of long-term mortality.

The Opportunities and Challenges regarding Induced Platelets from Human Pluripotent Stem Cells

As a standard clinical treatment, platelet transfusion has been employed to prevent hemorrhage in patients with thrombocytopenia or platelet dysfunctions. Platelets also show therapeutic potential for aiding liver regeneration and bone healing and regeneration and for treating dermatological conditions. However, the supply of platelets rarely meets the rising clinical demand. Other issues, including short shelf life, strict storage temperature, and allogeneic immunity caused by frequent platelet transfusions, have become serious challenges that require the development of high-yielding alternative sources of platelets. Human pluripotent stem cells (hPSCs) are an unlimited substitution source for regenerative medicine, and patient-derived iPSCs can provide novel research models to explore the pathogenesis of some diseases. Many studies have focused on establishing and modifying protocols for generating functional induced platelets (iPlatelets) from hPSCs. To reach high efficiency production and eliminate the exogenous antigens, media supplements and matrix have been optimized. In addition, the introduction of some critical transgenes, such as c-MYC, BMI1, and BCL-XL, can also significantly increase hPSC-derived platelet production; however, this may pose some safety concerns. Furthermore, many novel culture systems have been developed to scale up the production of iPlatelets, including 2D flow systems, 3D rotary systems, and vertical reciprocal motion liquid culture bioreactors. The development of new gene-editing techniques, such as CRISPR/Cas9, can be used to solve allogeneic immunity of platelet transfusions by knocking out the expression of B2M. Additionally, the functions of iPlatelets were also evaluated from multiple aspects, including but not limited to morphology, structure, cytoskeletal organization, granule content, DNA content, and gene expression. Although the production and functions of iPlatelets are close to meeting clinical application requirements in both quantity and quality, there is still a long way to go for their large-scale production and clinical application. Here, we summarize the diverse methods of platelet production and update the progresses of iPlatelets. Furthermore, we highlight recent advances in our understanding of key transcription factors or molecules that determine the platelet differentiation direction.

Monocyte upregulation of podoplanin during early sepsis induces complement inhibitor release to protect liver function

Multiple organ failure in sepsis is a progressive failure of several interdependent organ systems. Liver dysfunction occurs early during sepsis and is directly associated with patient death; however, the underlying mechanism of liver dysfunction is unclear. Platelet transfusion benefits patients with sepsis, and inhibition of complement activation protects liver function in septic animals. Herein, we explored the potential link between platelets, complement activation, and liver dysfunction in sepsis. We found that deletion of platelet C-type lectin-like receptor 2 (CLEC-2) exacerbated liver dysfunction in early sepsis. Platelet CLEC-2-deficient mice exhibited higher complement activation, more severe complement attack in the liver, and lower plasma levels of complement inhibitors at early time points after E. coli infection. Circulating monocytes expressed the CLEC-2 ligand podoplanin in early sepsis, and podoplanin binding induced release of complement inhibitors from platelets. Injection of complement inhibitors released from platelets reduced complement attack and attenuated liver dysfunction in septic mice. These findings indicate a new function of platelets in the regulation of complement activation during sepsis.

Differential modulation of endothelial cell function by fresh frozen plasma

AIMS

In vivo studies suggest a positive influence of fresh frozen plasma (FFP) on endothelial properties and vascular barrier function, leading to improved outcomes in animal sepsis models as well as in major abdominal surgery. However, those effects are incompletely described. It was our aim to evaluate in vitro effects of FFP on endothelial key functions and to identify underlying mechanisms.

MATERIALS AND METHODS

Human pulmonary microvascular endothelial cells (HPMECs) were prestimulated with LPS, followed by incubation with FFP. Permeability for FITC-dextran was assessed, and intercellular gap formation was visualized. NF-κB nuclear translocation and expression of pro-inflammatory, pro-adhesion, and leakage-related genes were evaluated, and monocyte adhesion to ECs was assessed. Intracellular cAMP levels as well as phosphorylation of functional proteins were analyzed. In patients undergoing major abdominal surgery, Syndecan-1 serum levels were assessed prior to and following FFP transfusion.

KEY FINDINGS

Post-incubation of HPMVECs with FFP increased intracellular cAMP levels that had been decreased by preceding LPS stimulation. On one hand, this reduced endotoxin-mediated upregulation of IL-8, ICAM-1, VCAM-1, VEGF, and ANG-2. Impaired phosphorylation of functional proteins was restored, and intercellular cohesion and barrier function were rescued. On the other hand, NF-κB nuclear translocation as well as monocyte adhesion was markedly increased by the combination of LPS and FFP. Syndecan-1 serum levels were lower in surgery patients that were transfused with FFP compared to those that were not.

SIGNIFICANCE

Our data provide evidence for a differential modulation of crucial endothelial properties by FFP, potentially mediated by elevation of intracellular cAMP levels.

The value of platelet count in evaluating the degree of liver fibrosis in patients with chronic hepatitis B

Objective

To investigate the value of platelet count in evaluating the degree of liver fibrosis in patients with chronic hepatitis B (CHB).

Methods

A total of 158 CHB patients who underwent liver biopsy in our hospital were included, and the clinical characteristics of these patients were retrospectively analyzed. The diagnostic values of platelet count, aspartate aminotransferase‐to‐platelet ratio index (APRI), and the fibrosis index based on four factors (FIB‐4) for significant fibrosis (F ≥ 2) and early cirrhosis (F = 4) stages in CHB patients were assessed by the use of receiver operating characteristic (ROC) analysis.

Results

The median (F0: 221.0; F1: 210.0; F2: 188.0; F3: 171.0; and F4: 155.5) and mean rank (F0: 120.4; F1: 100.1; F2: 82.2; F3: 67.9; and F4: 49.5) of platelet count decreased along the aggravation of fibrosis (F0‐F4). The areas under the ROC curve for the platelet count in diagnosis of significant fibrosis stage was 0.70, which had no significant difference with FIB‐4 (0.73) and APRI (0.68) in diagnostic efficacy (P = .428). The areas under the ROC curve of platelet count in diagnosis of early cirrhosis were 0.72, which had no significant difference with FIB‐4 (0.76) and APRI (0.68) (P = .094).

Conclusion

The platelet count, as a simple and non‐invasive index, could evaluate the degree of liver fibrosis in CHB individuals. At the same time, the diagnostic efficiency of platelet count to evaluate the significant liver fibrosis and early cirrhosis is comparable to FIB‐4 and APRI.

Platelet count is closely associated with the severity of liver injury in patients with chronic hepatitis B virus infection: A cross-sectional study

Although the platelet count may provide clues regarding the severity of liver disease, there are currently no available data supporting the utility of the platelet count to evaluate the degree of liver injury in patients with chronic hepatitis B virus (HBV) infection. The present study aimed to determine the association between the platelet count and the severity of liver injury in patients with chronic HBV infection. A total of 941 patients were included and were stratified into a Child-Turcotte-Pugh (CTP) class A group and a CTP class B/C group using the CTP scoring system. A total of 53 patients underwent liver biopsy. The pathological stage F4 was defined as cirrhosis based on the METAVIR scoring system. Compared with that in patients with CTP class A, the platelet count in patients with CTP class B/C was lower (P<0.001). Similarly, for patients with normal alanine aminotransferase (ALT) levels, the platelet count was significantly different between the CTP class B/C and A groups (P<0.001). The platelet count was inversely correlated with the CTP score (r=-0.420, P<0.001) and independently associated with CTP grade B/C [odds ratio (OR), 0.994; 95% CI, 0.990-0.999; P=0.009]. The area under the receiver operating characteristic curve (AUC) of the platelet count to distinguish CTP grade B/C from A was 0.712 and 0.791, respectively, in all patients with HBV infection and the subset with normal ALT levels. In addition, compared to patients with chronic hepatitis B, patients with cirrhosis had a lower platelet count and higher aspartate transaminase-to-platelet ratio index (APRI) and fibrosis index based on four factors (FIB-4) (P<0.001). The platelet count was inversely correlated with FIB-4 (r=-0.855, P<0.001) and APRI (r=-0.741, P<0.001). The AUC for the platelet count to distinguish cirrhosis from chronic hepatitis B was 0.927 (sensitivity, 78.76%; specificity, 92.22%). Among patients who underwent liver biopsy, the platelet count in those with F4 was lower compared with that in patients with ≤F3 (P=0.013). The platelet count was inversely correlated with the pathological stage (r=-0.295, P=0.032) and was independently associated with F4 (OR, 0.978; 95% CI, 0.960-0.997; P=0.026). The AUC of the platelet count to distinguish F4 from patients with ≤F3 was 0.761. In conclusion, the platelet count may be used as a non-invasive marker to assess the severity of liver injury and of liver fibrosis in patients with chronic HBV infection.

Markers of liver regeneration-the role of growth factors and cytokines: a systematic review

BACKGROUND

Post-hepatectomy liver failure contributes significantly to postoperative mortality after liver resection. The prediction of the individual risk for liver failure is challenging. This review aimed to provide an overview of cytokine and growth factor triggered signaling pathways involved in liver regeneration after resection.

METHODS

MEDLINE and Cochrane databases were searched without language restrictions for articles from the time of inception of the databases till March 2019. All studies with comparative data on the effect of cytokines and growth factors on liver regeneration in animals and humans were included.

RESULTS

Overall 3.353 articles comprising 40 studies involving 1.498 patients and 101 animal studies were identified and met the inclusion criteria. All included trials on humans were retrospective cohort/observational studies. There was substantial heterogeneity across all included studies with respect to the analyzed cytokines and growth factors and the described endpoints.

CONCLUSION

High-level evidence on serial measurements of growth factors and cytokines in blood samples used to predict liver regeneration after resection is still lacking. To address the heterogeneity of patients and potential markers, high throughput serial analyses may offer a method to predict an individual's regenerative potential in the future.

Dynamics of Platelet Behaviors as Defenders and Guardians: Accumulations in Liver, Lung, and Spleen in Mice

Systemic platelet behaviors in experimental animals are often assessed by infusion of isotope-labeled platelets and measuring them under anesthesia. However, such procedures alter, therefore may not reveal, real-life platelet behaviors. 5-Hydroxytryptamine (5HT or serotonin) is present within limited cell-types, including platelets. In our studies, by measuring 5HT as a platelet-marker in non-anesthetized mice, we identified stimulation- and time-dependent accumulations in liver, lung, and/or spleen as important systemic platelet behaviors. For example, intravenous, intraperitoneal, or intragingival injection of lipopolysaccharide (LPS, a cell-wall component of Gram-negative bacteria), interleukin (IL)-1, or tumor necrosis factor (TNF)-α induced hepatic platelet accumulation (HPA) and platelet translocation into the sinusoidal and perisinusoidal spaces or hepatocytes themselves. These events occurred "within a few hours" of the injection, caused hypoglycemia, and exhibited protective or causal effects on hepatitis. Intravenous injection of larger doses of LPS into normal mice, or intravenous antigen-challenge to sensitized mice, induced pulmonary platelet accumulation (PPA), as well as HPA. These reactions occurred "within a few min" of the LPS injection or antigen challenge and resulted in shock. Intravenous injection of 5HT or a catecholamine induced a rapid PPA "within 6 s." Intravenous LPS injection, within a minute, increased the pulmonary catecholamines that mediate the LPS-induced PPA. Macrophage-depletion from liver and spleen induced "day-scale" splenic platelet accumulation, suggesting the spleen is involved in clearing senescent platelets. These findings indicate the usefulness of 5HT as a marker of platelet behaviors, and provide a basis for a discussion of the roles of platelets as both "defenders" and "guardians."

Biomarkers of Vascular Injury and Type 2 Diabetes: A Prospective Study, Systematic Review and Meta-Analysis

Data on biomarkers of vascular injury and type 2 diabetes (T2D) risk from prospective studies are lacking. We evaluated seven biomarkers of vascular injury in relation to T2D. Additionally, a meta-analysis was performed. From the EPIC–Heidelberg cohort, 2224 participants were followed-up from baseline for 16 (median) years. E-Selectin, P-Selectin, intercellular adhesion molecule 3 (ICAM3), thrombomodulin, thrombopoietin, glycoprotein IIb/IIIa and fibrinogen levels were measured in baseline blood samples. The systematic review and meta-analysis included prospective studies identified through MEDLINE and Web of Science that investigated the association between mentioned biomarkers and T2D. The study population included 55% women, median age was 50 years, and 163 developed T2D. ICAM3 was associated with lower T2D risk (fully adjusted HR_{highest vs. lowest} tertile 0.62 (95% CI: 0.43, 0.91)), but no other studies on ICAM3 were identified. Overall, fifteen studies were included in the systematic review and meta-analysis (6,171 cases). E-Selectin was associated with higher T2D risk HR_{per SD}: 1.34 (95% CI: 1.16, 1.54; I² = 63%, n = 9 studies), while thrombomodulin was associated with lower risk HR_{per SD}: 0.82 (95% CI: 0.71, 0.95; I² = 0%, n = 2 studies). In the EPIC–Heidelberg, ICAM3 was associated with lower T2D risk. The meta-analysis showed a consistent positive association between E-Selectin and T2D. It was also suggestive of an inverse association between thrombomodulin and T2D, although further studies are needed to corroborate this finding.

"Let my liver rather heat with wine" - a review of hepatic fibrosis pathophysiology and emerging therapeutics

Cirrhosis is characterized by extensive hepatic fibrosis, and it is the 14th leading cause of death worldwide. Numerous contributing conditions have been implicated in its development, including infectious etiologies, medication overdose or adverse effects, ingestible toxins, autoimmunity, hemochromatosis, Wilson’s disease and primary biliary cholangitis to list a few. It is associated with portal hypertension and its stigmata (varices, ascites, hepatic encephalopathy, combined coagulopathy and thrombophilia), and it is a major risk factor for hepatocellular carcinoma. Currently, orthotopic liver transplantation has been the only curative modality to treat cirrhosis, and the scarcity of donors results in many people waiting years for a transplant. Identification of novel targets for pharmacologic therapy through elucidation of key mechanistic components to induce fibrosis reversal is the subject of intense research. Development of robust models of hepatic fibrosis to faithfully characterize the interplay between activated hepatic stellate cells (the principal fibrogenic contributor to fibrosis initiation and perpetuation), hepatocytes and extracellular matrix components has the potential to identify critical components and mechanisms that can be exploited for targeted treatment. In this review, we will highlight key cellular pathways involved in the pathophysiology of fibrosis from extracellular ligands, effectors and receptors, to nuclear receptors, epigenetic mechanisms, energy homeostasis and cytokines. Further, molecular pathways of hepatic stellate cell deactivation are discussed, including apoptosis, senescence and reversal or transdifferentiation to an inactivated state resembling quiescence. Lastly, clinical evidence of fibrosis reversal induced by biologics and small molecules is summarized, current compounds under clinical trials are described and efforts for treatment of hepatic fibrosis with mesenchymal stem cells are highlighted. An enhanced understanding of the rich tapestry of cellular processes identified in the initiation, perpetuation and resolution of hepatic fibrosis, driven principally through phenotypic switching of hepatic stellate cells, should lead to a breakthrough in potential therapeutic modalities.

Platelet TGF-β1 deficiency decreases liver fibrosis in a mouse model of liver injury

Transforming growth factor-β1 (TGF-β1) signaling in hepatic stellate cells (HSCs) plays a primary role in liver fibrosis, but the source of TGF-β1 is unclear. Because platelets are rich in TGF-β1, we examined the role of platelet TGF-β1 in liver fibrosis by challenging wild-type (WT) mice and mice deficient in platelet TGF-β1 (PF4CreTgfb1^f/f) with carbon tetrachloride (CCl₄), an inducer of acute hepatic injury and chronic fibrosis. CCl₄ elicited equivalent hepatic injury in WT and PF4CreTgfb1^f/f mice based on loss of cytochrome P450 (Cyp2e1) expression, observed at 6 hours and peaking at 3 days after CCl₄ challenge; PF4CreTgfb1^f/f mice exhibited less liver fibrosis than control mice. Activated platelets were observed during acute liver injury (6 hours), and WT mice with transient platelet depletion (thrombocytopenia) were partially protected from developing fibrosis compared with control mice (P = .01), suggesting an association between platelet activation and fibrosis. Transient increases in TGF-β1 levels and Smad2 phosphorylation signaling were observed 6 hours and 3 days, respectively, after CCl₄ challenge in WT, but not PF4CreTgfb1^f/f , mice, suggesting that increased TGF-β1 levels originated from platelet-released TGF-β1 during the initial injury. Numbers of collagen-producing HSCs and myofibroblasts were higher at 3 days and 36 days, respectively, in WT vs PF4CreTgfb1^f/f mice, suggesting that platelet TGF-β1 may have stimulated HSC transdifferentiation into myofibroblasts. Thus, platelet TGF-β1 partially contributes to liver fibrosis, most likely by initiating profibrotic signaling in HSCs and collagen synthesis. Further studies are required to evaluate whether blocking platelet and TGF-β1 activation during acute liver injury prevents liver fibrosis.

Low platelet count: Predictor of death and graft loss after liver transplantation

BACKGROUND

The impact of platelets on liver transplantation (LT) is well recognized, but not completely understood. Platelets exert dichotomous effects on the graft and on the patient. On the one hand, they are essential for primary hemostasis and tissue repair and regeneration. On the other hand, they support ischemia/reperfusion injury and inflammatory processes. Recent evidence has shown a new role for platelet count (PC) in predicting outcomes after LT.

AIM

To evaluate if low PC is a predictor of short- and long-term outcomes after LT.

METHODS

Four hundred and eighty consecutive LT patients were retrospectively assessed. PC from the preoperative to the seventh postoperative day (POD) were considered. C-statistic analysis defined the ideal cutoff point for PC. Cox regression was performed to check whether low PC was a predictor of death, retransplantation or primary changes in graft function within one year after LT.

RESULTS

The highest median PC was 86 × 10⁹/L [interquartile range (IQR) = 65–100 × 10⁹/L] on seventh POD, and the lowest was 51 × 10⁹/L (IQR = 38–71 × 10⁹/L) on third POD. The C-statistic defined a PC < 70 × 10⁹/L on fifth POD as the ideal cutoff point for predicting death and retransplantation. In the multivariate analysis, platelets < 70 × 10⁹/L on 5POD was an independent risk factor for death at 12 mo after LT [hazard ratio (HR) = 2.01; 95% confidence interval (CI) 1.06-3.79; P = 0.031]. In the Cox regression, patients with PC < 70 × 10⁹/L on 5POD had worse graft survival rates up to one year after LT (HR = 2.76; 95%CI 1.52-4.99; P = 0.001).

CONCLUSION

PC < 70 × 10⁹/L on 5POD is an independent predictor of death in the first year after LT. These results are in agreement with other studies that indicate that low PC after LT is associated with negative outcomes.

Role of Metabolism in Hepatic Stellate Cell Activation and Fibrogenesis

Activation of hepatic stellate cell (HSC) involves the transition from a quiescent to a proliferative, migratory, and fibrogenic phenotype (i.e., myofibroblast), which is characteristic of liver fibrogenesis. Multiple cellular and molecular signals which contribute to HSC activation have been identified. This review specially focuses on the metabolic changes which impact on HSC activation and fibrogenesis.

Preoperative Thrombocytopenia May Predict Poor Surgical Outcome after Extended Hepatectomy

Background

It is a novel idea that platelet counts may be associated with postoperative outcome following liver surgery. This may help in planning an extended hepatectomy (EH), which is a surgical procedure with high morbidity and mortality.

Aim

The aim of this study was to evaluate the predictive potential of platelet counts on the outcome of EH in patients without portal hypertension, splenomegaly, or cirrhosis.

Methods

A series of 213 consecutive patients underwent EH (resection of ≥ five liver segments) between 2001 and 2016. The association of preoperative platelet counts with posthepatectomy liver failure (PHLF), morbidity (based on Clavien-Dindo classification), and 30-day mortality was evaluated using multivariate analysis.

Results

PHLF was detected in 26.3% of patients, major complications in 26.8%, and 30-day mortality in 11.3% of patients. Multivariate analysis revealed that the preoperative platelet count is an independent predictor of PHLF (odds ratio [OR] 4.4, 95% confidence interval [CI] 1.3-15.0, p=0.020) and 30-day mortality (OR 4.4, 95% CI 1.1-18.8, p=0.043).

Conclusions

Preoperative platelet count is associated with PHLF and mortality following extended liver resection. This association was independent of other related parameters. Prospective studies are needed to evaluate the predictive role and to determine the impact of preoperative correction of platelet count on postoperative outcomes after EH.

A study on the regenerative effect of platelet-rich plasma on experimentally induced hepatic damage in albino rats

Hepatic fibrosis is a worldwide health problem with significant morbidity and mortality. Currently, there is no effective therapy for hepatic fibrosis. The present study was aimed to evaluate the possible regenerative effect of platelet-rich plasma (PRP) against thioacetamide (TAA)-induced hepatic damage. Eighty albino rats were included; 40 were used for PRP preparation and 40 were randomly divided into 4 groups: group I (control group); group II (PRP control); group III (TAA-intoxicated by a dose of 200 mg/kg body mass, intraperitoneally, twice weekly for 7 weeks), and group IV (TAA intoxicated + PRP treated). Macrophage inflammatory protein-1α (MIP-1α) and cyclic adenosine monophosphate (cAMP) were immunoassayed in addition to peroxinitrite level, NADPH-quinone oxidoreductase-1 (NQO1) enzyme activity, and liver function. PRP treatment showed significant improvement in hepatic function, and decreased MIP-1α and peroxinitrite levels. Meanwhile, significant increase in NQO1 enzyme activity and cAMP level were observed. The histopathological results confirmed the laboratory results with improvement of hepatic architecture except for some inflammatory cellular infiltrates. This study shows that PRP has the ability to protect against TAA-induced liver damage, possibly by improving redox status, liver histopathological architecture, and disruption of the inflammatory and fibrotic response induced by TAA.

Platelets in liver regeneration

Background and Objectives

Loss of liver tissue leading to impairment of liver function represents a major cause of mortality. Understanding the mechanism of liver regeneration and developing therapies to sustain liver regeneration are of high therapeutic relevance. In this regard, platelets are considered as potential candidates for stimulating liver regeneration.

Methods

We aim to review the most recent evidence regarding the role of platelets in liver regeneration.

Results

Platelets stimulate liver regeneration in animal models of liver resection. In humans, platelets are independent predictors of postoperative mortality, liver function and volume recovery. One proposed mechanism by which platelets stimulate liver regeneration relies on their direct effect on hepatocytes. Following partial hepatectomy, platelets accumulate in the residual liver and release their granule content. Platelet‐containing molecules, such as HGF, VEGF, IGF‐1 and serotonin, stimulate hepatocyte proliferation. A putative additional mechanism involves the transfer of platelet mRNA to hepatocytes following platelet internalization. Recent studies have suggested that the effect of platelets relies on their interactions with LSEC. Platelets induce the secretion of IL‐6 from LSEC, a strong initiator of hepatocyte proliferation. Additionally, platelets convey molecules that may impact LSEC function and, by extension, liver regeneration. Platelets potentially interact with Kupffer cells, but the effect of that interaction on liver regeneration remains to be determined.

Conclusion

Platelets stimulate liver regeneration. Several mechanisms seem to be involved, acting on the level of hepatocytes, LSEC and potentially Kupffer cells. Identification of the platelet‐molecule(s) involved may lead to targeted therapies for patients with impairment of liver function.

Association of interleukin-28B polymorphisms with platelet count and liver function recovery after liver transplant

The present genome-wide association study investigated the relationship of interleukin 28B (IL-28B) genetic variants with HBV susceptibility and prognosis of HBV-infected patients. This study aims to examine the role of IL-28B polymorphisms on transplant etiologies and the liver function recovery in Chinese liver transplant recipients.A total of 231 liver transplant recipients were enrolled in the study. The transplant etiologies included progressive HBV hepatitis, HBV-related liver cirrhosis (LC), HBV-related hepatocellular carcinoma (HCC), and non-HBV-related disease. All recipients were in stable condition before transplantation. Three single nucleotide polymorphisms (SNPs) of IL-28B (rs12979860, rs12980275, rs8099917) of recipients were analyzed by high-resolution melting (HRM) curve analysis. Liver function, blood cell count, and coagulation function were regularly tested before and for next 5 years after transplantation.No significant association was found between IL-28B gene polymorphisms and transplant etiologies. Peripheral platelet count in the third and fourth days after transplantation were significantly higher in recipients carrying IL-28B rs12979860 T allele, or rs8099917 C allele (P < .016666667), while there were no significant differences between these variants and International Normalized Ratio (INR) levels. In addition, gamma-glutamyltransferase (GGT) levels in recipients with rs12980275 G allele were higher than those in the wide-type recipients before transplantation (P < .016666667, respectively); nevertheless, no influence of these variants on GGT recovery was observed after transplantation.Genetic variations of IL-28B might impact on liver function recovery by influencing peripheral platelet counts and reducing liver inflammation, but have weak association with transplant etiologies.

Engineering in vitro models of hepatofibrogenesis

Chronic liver disease is a major cause of morbidity and mortality worldwide marked by chronic inflammation and fibrosis/scarring, resulting in end-stage liver disease and its complications. Hepatic stellate cells (HSCs) are a dominant contributor to liver fibrosis by producing excessive extracellular matrix (ECM), irrespective of the underlying disease aetiologies, and for many decades research has focused on the development of a number of anti-fibrotic strategies targeting this cell. Despite major improvements in two-dimensional systems (2D) by using a variety of cell culture models of different complexity, an efficient anti-fibrogenic therapy has yet to be developed. The development of well-defined three-dimensional (3D) in vitro models, which mimic ECM structures as found in vivo, have demonstrated the importance of cell-matrix bio-mechanics, the complex interactions between HSCs and hepatocytes and other non-parenchymal cells, and this to improve and promote liver cell-specific functions. Henceforth, refinement of these 3D in vitro models, which reproduce the liver microenvironment, will lead to new objectives and to a possible new era in the search for antifibrogenic compounds.

Mechanisms of hepatic stellate cell activation

Hepatic fibrosis is a dynamic process characterized by the net accumulation of extracellular matrix resulting from chronic liver injury of any aetiology, including viral infection, alcoholic liver disease and NASH. Activation of hepatic stellate cells (HSCs) - transdifferentiation of quiescent, vitamin-A-storing cells into proliferative, fibrogenic myofibroblasts - is now well established as a central driver of fibrosis in experimental and human liver injury. Yet, the continued discovery of novel pathways and mediators, including autophagy, endoplasmic reticulum stress, oxidative stress, retinol and cholesterol metabolism, epigenetics and receptor-mediated signals, reveals the complexity of HSC activation. Extracellular signals from resident and inflammatory cells including macrophages, hepatocytes, liver sinusoidal endothelial cells, natural killer cells, natural killer T cells, platelets and B cells further modulate HSC activation. Finally, pathways of HSC clearance have been greatly clarified, and include apoptosis, senescence and reversion to an inactivated state. Collectively, these findings reinforce the remarkable complexity and plasticity of HSC activation, and underscore the value of clarifying its regulation in hopes of advancing the development of novel diagnostics and therapies for liver disease.

Hemostasis, bleeding and thrombosis in liver disease

The presence of cirrhosis poses an increased risk of both thrombosis and bleeding in individuals with chronic liver disease. This duality is a result of a dynamic disequilibrium between procoagulant and anticoagulant states in individuals with cirrhosis. The mechanism of this imbalance in cirrhosis remains unclear. It is known that the progression of cirrhosis leads to decreased synthetic function and a concurrent lack of natural anticoagulants. Other proposed mechanisms contributing to this hemostatic imbalance include decreased platelet production, increased platelet destruction from hypersplenism, decreased synthesis of Vitamin K-dependent and independent clotting factors and anticoagulant factors, and alterations in purinergic signaling pathways.

Given the current state of flux in our understanding of bleeding and thrombophilia in cirrhosis, the recommendations for treatment of these conditions are still evolving.

We provide a current update on the proposed pathophysiology of altered hemostasis and thrombophilia in cirrhosis. We discuss recent studies in portal vein thrombosis (PVT) and venous thromboembolism (VTE), which are the common thrombotic consequences of cirrhosis, resulting in substantive morbidity and mortality. To address these, we discuss new prophylactic interventions and current treatment options to manage the heightened risk of thrombosis in cirrhosis, while limiting hemorrhagic complications.

Immune-Mediated Therapies for Liver Cancer

In recent years, immunotherapy has gained renewed interest as an alternative therapeutic approach for solid tumors. Its premise is based on harnessing the power of the host immune system to destroy tumor cells. Development of immune-mediated therapies, such as vaccines, adoptive transfer of autologous immune cells, and stimulation of host immunity by targeting tumor-evasive mechanisms have advanced cancer immunotherapy. In addition, studies on innate immunity and mechanisms of immune evasion have enhanced our understanding on the immunology of liver cancer. Preclinical and clinical studies with immune-mediated therapies have shown potential benefits in patients with liver cancer. In this review, we summarize current knowledge and recent developments in tumor immunology by focusing on two main primary liver cancers: hepatocellular carcinoma and cholangiocarcinoma.

Physiologic and pathophysiologic roles of interaction between C-type lectin-like receptor 2 and podoplanin: partners from in utero to adulthood

A platelet activation receptor, C-type lectin-like receptor 2 (CLEC-2), has been identified as a receptor for a platelet-activating snake venom, rhodocytin. CLEC-2 protein is highly expressed in platelets/megakaryocytes, and at lower levels in liver Kupffer cells. Recently, podoplanin has been revealed as an endogenous ligand for CLEC-2. Podoplanin is expressed in certain types of tumor cells, fibroblastic reticular cells (FRCs) in lymph nodes, kidney podocytes, and lymphatic endothelial cells, but not in vascular endothelial cells. CLEC-2 in platelets cannot have access to podoplanin under normal conditions, but they interact with each other under pathologic conditions or during developmental stages, and play various pathophysiologic roles. CLEC-2 facilitates hematogenous metastasis of podoplanin-expressing tumors. During development, the interaction between CLEC-2 and podoplanin in lymphatic endothelial cells or neuroepithelial cells facilitates blood-lymphatic vessel separation and cerebrovascular patterning and integrity, respectively. In adulthood, platelet CLEC-2 binding to FRCs is crucial for maintenance of the integrity of high endothelial venules in lymph nodes. Podoplanin-expressing FRC-like cells have recently been identified in the bone marrow, and facilitate megakaryocyte proliferation and proplatelet formation by binding to megakaryocyte CLEC-2. Podoplanin is inducibly expressed in liver monocytes and keratinocytes during Salmonella infection and wound healing, and regulates thrombus formation in the liver and controlled wound healing, respectively. By binding to unknown ligands, platelet CLEC-2 regulates the maintenance of vascular integrity during inflammation, thrombus stability under flow, and maintenance of quiescence of hematopoietic stem cells. Podoplanin is expressed in various cells, and additional roles of the CLEC-2-podoplanin interaction will be revealed in the future.

Brain-Derived Neurotrophic Factor in Children and Adolescents with Cirrhosis Due to Biliary Atresia

BACKGROUND

The nutritional status in patients with cirrhosis is not so easy to assess properly. Considering the relationship between brain-derived neurotrophic factor (BDNF) and energy homeostasis, the main aim of this study was to evaluate the concentration of BDNF in children and adolescents with cirrhosis due to biliary atresia (BA) and correlate it with their nutritional status.

METHODS

Fifty-three children and adolescents with cirrhosis due to BA and 33 healthy controls were enrolled in this study. Nutritional status was evaluated using anthropometric parameters, and serum BDNF was measured by ELISA. Spearman coefficient was used to evaluate the correlation between variables.

RESULTS

In the cirrhosis group, 28.8% were undernourished and in the control group, 100% were well-nourished. BDNF median values for the control and cirrhosis group were 28.5 and 9.0 pg/ml respectively. BDNF and platelets were positively associated with both Standard Deviation Score (SDS) for height-for-age ratio and SDS for triceps skinfold thickness-for-age ratio.

CONCLUSIONS

Considering these associations, BDNF may be an indirect biomarker of nutritional status in children and adolescents with chronic liver disease. Further studies must be conducted to clarify the role of BDNF in this population.