Till Death Do Us Part-The Multifaceted Role of Platelets in Liver Diseases

Nonlinear relationship between platelet count and 30-day in-hospital mortality in ICU acute respiratory failure patients: a multicenter retrospective cohort study

BACKGROUND

Limited evidence exists regarding the link between platelet count and 30-day in-hospital mortality in acute respiratory failure (ARF) patients. Thus, this study aims to investigate this association among ICU patients experiencing acute respiratory failure.

METHODS

We conducted a retrospective cohort study across multiple centers, utilizing data from the US eICU-CRD v2.0 database covering 22,262 patients with ARF in the ICU from 2014 to 2015. Our aim was to investigate the correlation between platelet count and 30-day in-hospital mortality using binary logistic regression, subgroup analyses, and smooth curve fitting.

RESULTS

The 30-day in-hospital mortality rate was 19.73% (4393 out of 22,262), with a median platelet count of 213 × 109/L. After adjusting for covariates, our analysis revealed an inverse association between platelet count and 30-day in-hospital mortality (OR = 0.99, 95% CI 0.99, 0.99). Subgroup analyses supported the robustness of these findings. Furthermore, a nonlinear relationship was identified between platelet count and 30-day in-hospital mortality, with the inflection point at 120 × 109/L. Below the inflection point, the effect size (OR) was 0.89 (0.87, 0.91), indicating a significant association. However, beyond this point, the relationship was not statistically significant.

CONCLUSION

This study establishes a clear negative association between platelet count and 30-day in-hospital mortality among ICU patients with ARF. Furthermore, we have identified a nonlinear relationship with saturation effects, indicating that among ICU patients with acute respiratory failure, the lowest 30-day in-hospital mortality rate occurs when the baseline platelet count is approximately 120 × 109/L.

Targeted platelet with hydrogen peroxide responsive behavior for non-alcoholic steatohepatitis detection

The most common chronic liver illness, non-alcoholic fatty liver disease (NAFLD), refers to a range of abnormalities of the liver with varying degrees of steatosis. When the clinical symptoms including liver damage, inflammation, and fibrosis, are added to the initial steatosis, NAFLD becomes non-alcoholic steatohepatitis (NASH), the problematic and severe stage. The diagnosis of NASH at the right time could therefore effectively prevent deterioration of the disease. Considering that platelets (PLTs) could migrate to the sites of inflamed liver sinusoids with oxidative stress during the development of NASH, we purified the PLTs from fresh blood and engineered their surface with hydrogen peroxide (H2O2) responsive fluorescent probe (5-DP) through lipid fusion. The engineered PLT-DPs were recruited and trapped in the inflammation foci of the liver with NASH through interaction with the extracellular matrix, including hyaluronan and Kupffer cells. Additionally, the fluorescence of 5-DP on the surface of PLT-DP was significantly enhanced upon reacting with the elevated level of H2O2 in the NASH liver. Thus, PLT-DP has great promise for NASH fluorescence imaging with high selectivity and sensitivity.

Platelet-associated biomarkers in nonalcoholic steatohepatitis: Insights from a female cohort with obesity

BACKGROUND

There is a lack of noninvasive diagnostic methods for nonalcoholic steatohepatitis (NASH), the severe condition of metabolic dysfunction-associated steatotic liver disease (MASLD). Platelet activation, evaluated through certain related parameters, is associated with liver disease and inflammation, but previous results are inconclusive.

AIM

To investigate the potential utility of platelet-related indices as noninvasive diagnostic markers for the detection and prediction of MASLD, focusing on NASH.

RESULTS

We found that mean platelet volume (MPV), plateletcrit (PCT) and platelet distribution width (PDW) were increased in the severe and morbidly obese (SMO) group compared to the normal weight (NW) group. We found decreased levels of MPV in steatosis and NASH patients. MPV and PCT values were decreased in the presence of mild liver inflammation. Platelet count (PLA) and PCT values were lower in the presence of ballooning. We obtained an area under the ROC curve of 0.84 using MPV and three other variables to predict MASLD.

CONCLUSIONS

Some platelet-related indices vary depending on liver condition. Here, we reported decreased MPV in MASLD presence. Moreover, we presented for the first time a predictive model using MPV, ALT levels and the presence of diabetes mellitus and metabolic syndrome to predict MASLD in obese women. Also, MPV is closely related to early liver inflammation in NASH, and PLA and PCT are related to hepatic ballooning. These indices could be widely used for the early detection of NASH since they are usually determined in routine laboratory tests.

The Interplay between Liver Sinusoidal Endothelial Cells, Platelets, and Neutrophil Extracellular Traps in the Development and Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a societal burden due to the lack of effective treatment and incomplete pathophysiology understanding. This review explores the intricate connections among liver sinusoidal endothelial cells (LSECs), platelets, neutrophil extracellular traps (NETs), and coagulation disruptions in MASLD pathogenesis. In MASLD's early stages, LSECs undergo capillarization and dysfunction due to excessive dietary macronutrients and gut-derived products. Capillarization leads to ischemic changes in hepatocytes, triggering pro-inflammatory responses in Kupffer cells (KCs) and activating hepatic stellate cells (HSCs). Capillarized LSECs show a pro-inflammatory phenotype through adhesion molecule overexpression, autophagy loss, and increased cytokines production. Platelet interaction favors leucocyte recruitment, NETs formation, and liver inflammatory foci. Liver fibrosis is facilitated by reduced nitric oxide, HSC activation, profibrogenic mediators, and increased angiogenesis. Moreover, platelet attachment, activation, α-granule cargo release, and NETs formation contribute to MASLD progression. Platelets foster fibrosis and microthrombosis, leading to parenchymal extinction and fibrotic healing. Additionally, platelets promote tumor growth, epithelial-mesenchymal transition, and tumor cell metastasis. MASLD's prothrombotic features are exacerbated by insulin resistance, diabetes, and obesity, manifesting as increased von Willebrand factor, platelet hyperaggregability, hypo-fibrinolysis, and a prothrombotic fibrin clot structure. Improving LSEC health and using antiplatelet treatment appear promising for preventing MASLD development and progression.

Role of Perturbated Hemostasis in MASLD and Its Correlation with Adipokines

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) continues to rise, making it one of the most prevalent chronic liver disorders. MASLD encompasses a range of liver pathologies, from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH) with inflammation, hepatocyte damage, and fibrosis. Interestingly, the liver exhibits close intercommunication with fatty tissue. In fact, adipose tissue could contribute to the etiology and advancement of MASLD, acting as an endocrine organ that releases several hormones and cytokines, with the adipokines assuming a pivotal role. The levels of adipokines in the blood are altered in people with MASLD, and recent research has shed light on the crucial role played by adipokines in regulating energy expenditure, inflammation, and fibrosis in MASLD. However, MASLD disease is a multifaceted condition that affects various aspects of health beyond liver function, including its impact on hemostasis. The alterations in coagulation mechanisms and endothelial and platelet functions may play a role in the increased vulnerability and severity of MASLD. Therefore, more attention is being given to imbalanced adipokines as causative agents in causing disturbances in hemostasis in MASLD. Metabolic inflammation and hepatic injury are fundamental components of MASLD, and the interrelation between these biological components and the hemostasis pathway is delineated by reciprocal influences, as well as the induction of alterations. Adipokines have the potential to serve as the shared elements within this complex interrelationship. The objective of this review is to thoroughly examine the existing scientific knowledge on the impairment of hemostasis in MASLD and its connection with adipokines, with the aim of enhancing our comprehension of the disease.

New and Old Key Players in Liver Cancer

Liver cancer represents a major health problem worldwide with growing incidence and high mortality, hepatocellular carcinoma (HCC) being the most frequent. Hepatocytes are likely the cellular origin of most HCCs through the accumulation of genetic alterations, although hepatic progenitor cells (HPCs) might also be candidates in specific cases, as discussed here. HCC usually develops in a context of chronic inflammation, fibrosis, and cirrhosis, although the role of fibrosis is controversial. The interplay between hepatocytes, immune cells and hepatic stellate cells is a key issue. This review summarizes critical aspects of the liver tumor microenvironment paying special attention to platelets as new key players, which exert both pro- and anti-tumor effects, determined by specific contexts and a tight regulation of platelet signaling. Additionally, the relevance of specific signaling pathways, mainly HGF/MET, EGFR and TGF-β is discussed. HGF and TGF-β are produced by different liver cells and platelets and regulate not only tumor cell fate but also HPCs, inflammation and fibrosis, these being key players in these processes. The role of C3G/RAPGEF1, required for the proper function of HGF/MET signaling in HCC and HPCs, is highlighted, due to its ability to promote HCC growth and, regulate HPC fate and platelet-mediated actions on liver cancer.

Macrophages and platelets in liver fibrosis and hepatocellular carcinoma

During fibrosis, (myo)fibroblasts deposit large amounts of extracellular matrix proteins, thereby replacing healthy functional tissue. In liver fibrosis, this leads to the loss of hepatocyte function, portal hypertension, variceal bleeding, and increased susceptibility to infection. At an early stage, liver fibrosis is a dynamic and reversible process, however, from the cirrhotic stage, there is significant progression to hepatocellular carcinoma. Both liver-resident macrophages (Kupffer cells) and monocyte-derived macrophages are important drivers of fibrosis progression, but can also induce its regression once triggers of chronic inflammation are eliminated. In liver cancer, they are attracted to the tumor site to become tumor-associated macrophages (TAMs) polarized towards a M2- anti-inflammatory/tumor-promoting phenotype. Besides their role in thrombosis and hemostasis, platelets can also stimulate fibrosis and tumor development by secreting profibrogenic factors and regulating the innate immune response, e.g., by interacting with monocytes and macrophages. Here, we review recent literature on the role of macrophages and platelets and their interplay in liver fibrosis and hepatocellular carcinoma.

The clinical value of the monocyte to high-density lipoprotein cholesterol ratio and alkaline phosphatase-to-platelet ratio in primary biliary cholangitis

This study aimed to evaluate the clinical value of the monocyte to high-density lipoprotein cholesterol ratio (MHR) and alkaline phosphatase-to-platelet ratio (APPR) in the diagnosis and prognosis of primary biliary cholangitis (PBC). Clinical and laboratory data were retrospectively collected and analyzed from 92 PBC patients, 92 patients with autoimmune hepatitis (AIH), 120 patients with chronic hepatitis B (CHB) and 124 healthy controls (HCs). We compared the levels of MHR and APPR among the groups with PBC, AIH, CHB and HCs, and analyzed the correlations between MHR and APPR with laboratory indices including aspartate aminotransferase platelet ratio index, fibrosis index based on 4 factors, and Mayo score in PBC. Receiver operating characteristic curves were used to analyze the diagnostic performance of MHR and APPR for PBC, AIH, and CHB, respectively. MHR and APPR were significantly increased in PBC group than that in AIH, CHB and HCs groups (each P < .05). MHR and APPR were significantly higher in Child class B|C than that in class A in PBC patients. (P < .01, P < .05, respectively). MHR and APPR were positively related to the Mayo score [R = 0.508 (P < .001), R = 0.295 (P = .008), respectively]. The area under the receiver operating characteristic curves of MHR and APPR in diagnosing PBC were 0.764 (95% confidence interval [CI]: 0.699-0.821, P < .001) and 0.952 (95% CI: 0.915-0.977, P < .001), respectively, and the area under the curve of the combination of both was 0.974 (95% CI: 0.941-0.991, P < .001). MHR and APPR may prove to be useful prognostic biomarkers for PBC, and the combination of MHR and APPR have some clinical diagnostic value of PBC.

Selective Internal Radiotherapy Alters the Profiles of Systemic Extracellular Vesicles in Hepatocellular Carcinoma

Incidence of hepatocellular carcinoma (HCC) is increasing globally. Radioembolization (RE)/selective internal radiotherapy (SIRT) is a promising treatment for inoperable HCC. RE triggers an immune response, involving extracellular vesicles (EVs) which are crucial for cell communication and tumor development. This study explores EV immune profiles and origins in patients with inoperable HCC before and after SIRT/RE. Blood samples from 50 HCC-patients treated with SIRT/RE were collected before and after therapy to determine cytokines and isolate EVs using size exclusion chromatography. The dynamic range and EV quality required for detecting variations in surface markers were assessed. Thirty-seven EV surface markers were analyzed using flow cytometry and correlated with clinical parameters. Several immunological markers (CD4, CD2, CD40, CD45, CD49e, CD69, CD209-EVs) were present in the circulation of HCC patients. These markers positively correlated with therapy response and survival. Conversely, B cell CD20, endothelial cell CD146, platelet CD49e, and CD41b EV markers negatively correlated with 60-day survival. Elevated levels of IL-6 and IL-8 before therapy correlated negatively with patient survival, coinciding with a positive correlation with CD20-positive EVs. Plasma EVs from HCC patients exhibit immunological, cancer, and coagulation markers, including potential biomarkers (CD4, CD20, CD49e, CD146). These may enhance our understanding of cancer biology and facilitate SIRT therapy monitoring.

Utility of neutrophil-lymphocyte ratio and platelet-lymphocyte ratio in predicting acute-on-chronic liver failure survival

This study explored the predictive value of the monocyte-to-lymphocyte ratio (MLR) and platelet-lymphocyte ratio (PLR) in patients with acute-on-chronic liver failure (ACLF). A retrospective analysis was carried out on 40 patients with ACLF from January 2018 and August 2019 in our hospital. The patient's clinical information during hospitalization was collected, and their survivals were followed for 3 months. MLR and PLR values of patients were compared, and the correlation between liver function indicators and prognosis was analyzed. We observed that MLR levels in the survival and death groups were 0.521 (0.311, 0.827) and 0.741 (0.442, 1.121), respectively. MLR levels were markedly enhanced in the death group compared to the survival group (P = 0.021). The receiver operating characteristic curve (ROC) exhibited that the area under the ROC curve and 95% confidence interval for the survival group was 0.641 (0.528-0.757). Survival analysis demonstrated that the 3-month survival of the high MLR group was markedly lower than that of the low MLR group (P = 0.001). Multivariate regression exposed that MLR and PLR were independent prognostic factors for ACLF. MLR and PLR could be prospective prognosticative markers of ACLF.

The potential curative and hepatoprotective effects of platelet rich plasma on liver fibrosis in Schistosoma mansoni experimentally infected mice

Trapped Schistosoma mansoni eggs trigger fibrotic liver disease that can continue to liver cirrhosis and failure. This work evaluates the outcome of platelet rich plasma (PRP) on S. mansoni-induced liver fibrosis by intraperitoneal (IP) and intrahepatic (IH) routes with/without Praziquantel (PZQ) treatment. Swiss albino mice (n = 162) were divided into non-infected (n = 66) and infected (n = 96) groups, then subdivided into non-treated and treated subgroups with PRP(IP), PRP(IH) 6th and 10th weeks post-infection, PZQ, PZQ + PRP(IP) and PZQ + PRP(IH) 6th and 10th weeks post-infection. Effects of treatments were evaluated by parasitological, histopathological and Immunohistochemical assessments. In the early assessment (12th week post-infection) of infected-treated groups, the mean granuloma number showed significant reduction in groups treated with PZQ + PRP (IH) 10th week, PRP (IP), PZQ + PRP (IP) and PZQ + PRP (IH) 6th week (33.33%, 33%, 27.77% and 27.22%, respectively). Furthermore, the mean granuloma diameter showed significant reduction in groups treated with PRP (IH) 10th week and PZQ + PRP (IP) (24.17% and 15.5%, respectively). Also, the fibrotic index showed significant reduction in groups treated with PZQ + PRP (IP), PRP (IP) and PZQ + PRP (IH) 6th week (48.18%, 46.81% and 41.36%, respectively). Transforming growth factor β1(TGF-β1) expression was in correlation with parasitological and histopathological results. Diminished TGF-β1 expression was mostly in infected groups treated with PZQ + PRP (IP), PZQ + PRP (IH) 6th week and PRP (IP) (88.63%, 88.63% and 77.27%, respectively). In the late assessment (14th week post-infection) of infected treated groups, TGF-β1expression was reduced in groups treated with PZQ, PRP (IH) 10th weeks, PRP (IP) (83.33%, 66.66%, 33.33% respectively). PRP showed promising anti-fibrotic effects on S. mansoni-induced liver fibrosis.

Overview of Cellular and Soluble Mediators in Systemic Inflammation Associated with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent chronic liver disease in Western countries, affecting approximately 25% of the adult population. This condition encompasses a spectrum of liver diseases characterized by abnormal accumulation of fat in liver tissue (non-alcoholic fatty liver, NAFL) that can progress to non-alcoholic steatohepatitis (NASH), characterized by the presence of liver inflammation and damage. The latter form often coexists with liver fibrosis which, in turn, may progress to a state of cirrhosis and, potentially, hepatocarcinoma, both irreversible processes that often lead to the patient's death and/or the need for liver transplantation. Along with the high associated economic burden, the high mortality rate among NAFLD patients raises interest, not only in the search for novel therapeutic approaches, but also in early diagnosis and prevention to reduce the incidence of NAFLD-related complications. In this line, an exhaustive characterization of the immune status of patients with NAFLD is mandatory. Herein, we attempted to gather and compare the current and relevant scientific evidence on this matter, mainly on human reports. We addressed the current knowledge related to circulating cellular and soluble mediators, particularly platelets, different leukocyte subsets and relevant inflammatory soluble mediators.

Application of tumor-educated platelets as new fluid biopsy markers in various tumors

The incidence of malignant tumors is increasing year by year. Early detection and diagnosis of malignant tumors can improve the prognosis of patients and prolong their life. Pathological biopsy is the current gold standard for diagnosis, but the results of pathological biopsy are affected by the sampling site and cannot fully reflect the nature of the disease. Moreover, the invasive nature of pathological biopsy limits repeated detection. Liquid biopsies are non-invasive and can be used for early detection and monitoring of tumors, which considered to represent a promising tool. Platelets make themselves to be one of the richest liquid biopsy sources by the capacity to take up proteins and nucleic acids and alter their megakaryocyte-derived transcripts and proteins in response to external signals, which are called tumor-educated platelets (TEPs). In this article, we will review the application of tumor-educated platelets in various malignancies (nasopharyngeal carcinoma, prostate cancer, lung cancer, glioblastoma, colorectal cancer, pancreas cancer, ovarian cancer, sarcoma, breast cancer and hepatocellular carcinoma) and provide theoretical basis for the research of TEPs in tumor diagnosis, monitoring and treatment.

The role of platelet mediated thromboinflammation in acute liver injury

Acute liver injuries have wide and varied etiologies and they occur both in patients with and without pre-existent chronic liver disease. Whilst the pathophysiological mechanisms remain distinct, both acute and acute-on-chronic liver injury is typified by deranged serum transaminase levels and if severe or persistent can result in liver failure manifest by a combination of jaundice, coagulopathy and encephalopathy. It is well established that platelets exhibit diverse functions as immune cells and are active participants in inflammation through processes including immunothrombosis or thromboinflammation. Growing evidence suggests platelets play a dualistic role in liver inflammation, shaping the immune response through direct interactions and release of soluble mediators modulating function of liver sinusoidal endothelial cells, stromal cells as well as migrating and tissue-resident leucocytes. Elucidating the pathways involved in initiation, propagation and resolution of the immune response are of interest to identify therapeutic targets. In this review the provocative role of platelets is outlined, highlighting beneficial and detrimental effects in a spatial, temporal and disease-specific manner.

Oral supplementation of policosanol alleviates carbon tetrachloride-induced liver fibrosis in rats

Liver fibrosis is a prevalent liver disease that requires rapid and effective treatment prior to its progression to cirrhosis and liver damage. Recently, several reports have investigated the efficacy of phytotherapy using natural herbal extracts rather than synthetic drugs to treat several liver diseases. Policosanol is a herbal extract used to treat patients with cardiovascular. However, its therapeutic effect on liver fibrosis is still unknown. Therefore, the present study aimed to assess the potential antifibrotic effect of policosanol compared to silymarin and the possible underlying molecular mechanisms. Rats were categorized into four groups; negative control group "NCG", the fibrotic group "FG", silymarin treated group "STG", and policosanol treated group "PTG". Serum liver enzymes, oxidative stress markers, angiogenic growth factors, and pro-inflammatory cytokines were measured biochemically. The relative mRNA expressions of liver caspase-3 and alpha-smooth muscle actin (α-SMA) were assessed. Immunohistochemical staining was carried out using anti- α-SMA, and anti-caspase-3 antibodies. Compared to NCG, the FG group demonstrated a significant decrease in the level of serum liver enzymes "GSH, TAC, and SDF. Nevertheless, it demonstrateda significant increase in the level of pro-inflammatory cytokines "Il-6, TNF"; oxidative stress markers "NO, MDA", and angiogenic growth factors "VEGF and PDGF" and the expression of α-SMA, and Caspase-3. Interestingly, the values of these measurements were restored to normal levels in the treated groups, particularly the PTG. In conclusion, our data revealed the beneficial effects of co-administration of policosanol or silymarin on the fibrotic liver rat model and thus could be a promising natural therapeutic drug.

Platelets in Non-alcoholic Fatty Liver Disease

Non alcoholic steatohepatitis (NASH) is the inflammatory reaction of the liver to excessive accumulation of lipids in the hepatocytes. NASH can progress to cirrhosis and hepatocellular carcinoma (HCC). Fatty liver is the hepatic manifestation of metabolic syndrome. A subclinical inflammatory state is present in patients with metabolic alterations like insulin resistance, type-2 diabetes, obesity, hyperlipidemia, and hypertension. Platelets participate in immune cells recruitment and cytokines-induced liver damage. It is hypothesized that lipid toxicity cause accumulation of platelets in the liver, platelet adhesion and activation, which primes the immunoinflammatory reaction and activation of stellate cells. Recent data suggest that antiplatelet drugs may interrupt this cascade and prevent/improve NASH. They may also improve some metabolic alterations. The pathophysiology of inflammatory liver disease and the implication of platelets are discussed in details.

Aspirin Attenuates Hyperoxia-Induced Acute Respiratory Distress Syndrome (ARDS) by Suppressing Pulmonary Inflammation via the NF-κB Signaling Pathway

Acute respiratory distress syndrome (ARDS) is a common destructive syndrome with high morbidity and mortality rates. Currently, few effective therapeutic interventions for ARDS are available. Clinical trials have shown that the effectiveness of aspirin is inconsistent. The contribution of platelets to the inflammatory response leading to the development of ARDS is increasingly recognized. The antiplatelet agent aspirin reportedly exerts a protective effect on acid- and hyperoxia-induced lung injury in murine models. Our previous study showed that pretreatment with aspirin exerts protective effects on hyperoxia-induced lung injury in mice. However, the mechanisms and therapeutic efficacy of aspirin in the posttreatment of hyperoxia-induced acute lung injury (ALI) remain unclear. In this study, we used a homozygous NF-κB-luciferase^+/+ transgenic mouse model and treated mice with low-dose (25 μg/g) or high-dose (50 μg/g) aspirin at 0, 24, and 48 h after exposure to hyperoxia (inspired oxygen fraction (FiO₂) > 95%). Hyperoxia-induced lung injury significantly increased the activation of NF-κB in the lung and increased the levels of macrophages infiltrating the lung and reactive oxygen species (ROS), increased the HO-1, NF-κB, TNF-α, IL-1β, and IL-4 protein levels, and reduced the CC10, SPC, eNOS, Nrp-1, and IκBα protein levels in the lung tissue. Pulmonary edema and alveolar infiltration of neutrophils were also observed in the lung tissue of mice exposed to hyperoxia. However, in vivo imaging revealed that posttreatment with aspirin reduced luciferase expression, suggesting that aspirin might reduce NF-κB activation. Posttreatment with aspirin also reduced hyperoxia-induced increases in the numbers of lung macrophages, intracellular ROS levels, and the expression of TNF-α, IL-1β, and IL-4; it also increased CC10, SPC and Nrp-1 levels compared with hyperoxia exposure alone. Lung histopathology also indicated that the aspirin posttreatment significantly reduced neutrophil infiltration and lung edema compared with hyperoxia exposure alone. Aspirin effectively induces an anti-inflammatory response in a model of hyperoxia-induced lung injury. Thus, aspirin may have potential as a novel treatment for hyperoxia-induced ALI.

Atypical Roles of the Chemokine Receptor ACKR3/CXCR7 in Platelet Pathophysiology

The manifold actions of the pro-inflammatory and regenerative chemokine CXCL12/SDF-1α are executed through the canonical GProteinCoupledReceptor CXCR4, and the non-canonical ACKR3/CXCR7. Platelets express CXCR4, ACKR3/CXCR7, and are a vital source of CXCL12/SDF-1α themselves. In recent years, a regulatory impact of the CXCL12-CXCR4-CXCR7 axis on platelet biogenesis, i.e., megakaryopoiesis, thrombotic and thrombo-inflammatory actions have been revealed through experimental and clinical studies. Platelet surface expression of ACKR3/CXCR7 is significantly enhanced following myocardial infarction (MI) in acute coronary syndrome (ACS) patients, and is also associated with improved functional recovery and prognosis. The therapeutic implications of ACKR3/CXCR7 in myocardial regeneration and improved recovery following an ischemic episode, are well documented. Cardiomyocytes, cardiac-fibroblasts, endothelial lining of the blood vessels perfusing the heart, besides infiltrating platelets and monocytes, all express ACKR3/CXCR7. This review recapitulates ligand induced differential trafficking of platelet CXCR4-ACKR3/CXCR7 affecting their surface availability, and in regulating thrombo-inflammatory platelet functions and survival through CXCR4 or ACKR3/CXCR7. It emphasizes the pro-thrombotic influence of CXCL12/SDF-1α exerted through CXCR4, as opposed to the anti-thrombotic impact of ACKR3/CXCR7. Offering an innovative translational perspective, this review also discusses the advantages and challenges of utilizing ACKR3/CXCR7 as a potential anti-thrombotic strategy in platelet-associated cardiovascular disorders, particularly in coronary artery disease (CAD) patients post-MI.

Relationship between Hepatitis B virus infection and platelet production and dysfunction

Hepatitis B virus (HBV) is a kind of hepatotropic DNA virus. The main target organ is liver, except for liver, HBV has been found in a variety of extrahepatic tissues, such as kidney, thyroid, pancreas, bone marrow, etc. HBV can cause severe complications by invading these tissues. Among them, pancytopenia is one of the common complications, especially thrombocytopenia that causes life-threatening bleeding. However, the mechanism of thrombocytopenia is unclear and the treatment is extremely difficult. It has been confirmed that HBV has a close relationship with platelets. HBV can directly infect bone marrow, inhibit platelet production, and accelerate platelet destruction by activating monocyte-macrophage system and immune system. While platelets act as a double-edged sword to HBV. On one hand, the activated platelets can degranulate and release inflammatory mediators to help clear the viruses. Furthermore, platelets can provide anti-fibrotic molecules to improve liver functions and reduce hepatic fibrosis. On the other hand, platelets can also cause negative effects. The infected platelets collect HBV-specific CD8⁺ T cells and nonspecific inflammatory cells into liver parenchyma, inducing chronic inflammation, liver fibrosis and hepatic carcinoma. This article explores the interaction between HBV infection and platelets, providing a theoretical basis for clinical treatment of thrombocytopenia and severe hemorrhage caused by HBV infection.