Innate immune cells induce hemorrhage in tumors during thrombocytopenia

Preoperative platelet count as an independent predictor of long-term outcomes among patients undergoing resection for intrahepatic cholangiocarcinoma

BACKGROUND AND OBJECTIVES

An elevated platelet count may reflect neoplastic and inflammatory states, with cytokine-driven overproduction of platelets. The objective of this study was to evaluate the prognostic utility of high platelet count among patients undergoing curative-intent liver surgery for intrahepatic cholangiocarcinoma (ICC).

METHODS

An international, multi-institutional cohort was used to identify patients undergoing curative-intent liver resection for ICC (2000-2020). A high platelet count was defined as platelets >300 *109/L. The relationship between preoperative platelet count, cancer-specific survival (CSS), and overall survival (OS) was examined.

RESULTS

Among 825 patients undergoing curative-intent resection for ICC, 139 had a high platelet count, which correlated with multifocal disease, lymph nodes metastasis, poor to undifferentiated grade, and microvascular invasion. Patients with high platelet counts had worse 5-year (35.8% vs. 46.7%, p = 0.009) CSS and OS (24.8% vs. 39.8%, p < 0.001), relative to patients with a low platelet count. After controlling for relevant clinicopathologic factors, high platelet count remained an adverse independent predictor of CSS (HR = 1.46, 95% CI 1.02-2.09) and OS (HR = 1.59, 95% CI 1.14-2.22).

CONCLUSIONS

High platelet count was associated with worse tumor characteristics and poor long-term CSS and OS. Platelet count represents a readily-available laboratory value that may preoperatively improve risk-stratification of patients undergoing curative-intent liver resection for ICC.

Cooperation Between Platelet β1 and β3 Integrins in the Arrest of Bleeding Under Inflammatory Conditions in Mice-Brief Report

BACKGROUND

Platelets prevent bleeding in a variety of inflammatory settings, the adhesion receptors and activation pathways involved being highly context-dependent and functionally redundant. In some situations, platelets recruited to inflammatory sites act independently of aggregation. The mechanisms underlying stable platelet adhesion in inflamed microvessels remain incompletely understood, in particular, whether and if so, how β1 and β3 integrins are involved.

METHODS

The impact of isolated or combined platelet deficiency in β1 and β3 integrins on inflammation-associated hemostasis was investigated in 3 models of acute inflammation: immune complex-based cutaneous reverse passive Arthus reaction, intranasal lipopolysaccharide-induced lung inflammation, and cerebral ischemia-reperfusion following transient (2-hour) occlusion of the middle cerebral artery.

RESULTS

Mice with platelet-directed inactivation of Itgb1 (PF4Cre-β1-/-) displayed no bleeding in any of the inflammation models, while mice defective in platelet Itgb3 (PF4Cre-β3-/-) exhibited bleeding in all 3 models. Remarkably, the bleeding phenotype of PF4Cre-β3-/- mice was exacerbated in the reverse passive Arthus model by the concomitant deletion of β1 integrins, PF4Cre-β1-/-/β3-/- animals presenting increased bleeding. Intravital microscopy in reverse passive Arthus experiments highlighted a major defect in the adhesion of PF4Cre-β1-/-/β3-/- platelets to inflamed microvessels. Unlike PF4Cre-β1-/- and PF4Cre-β3-/- mice, PF4Cre-β1-/-/β3-/- animals developed early hemorrhagic transformation 6 hours after transient middle cerebral artery occlusion. PF4Cre-β1-/-/β3-/- mice displayed no more bleeding in lipopolysaccharide-induced lung inflammation than PF4Cre-β3-/- animals.

CONCLUSIONS

Altogether, these results show that the requirement for and degree of functional redundancy between platelet β1 and β3 integrins in inflammation-associated hemostasis vary with the inflammatory situation.

The localization, origin, and impact of platelets in the tumor microenvironment are tumor type-dependent

BACKGROUND

How platelets interact with and influence the tumor microenvironment (TME) remains poorly characterized.

METHODS

We compared the presence and participation of platelets in the TME of two tumors characterized by highly different TME, PyMT AT-3 mammary tumors and B16F1 melanoma.

RESULTS

We show that whereas firmly adherent platelets continuously line tumor vessels of both AT-3 and B16F1 tumors, abundant extravascular stromal clusters of platelets from thrombopoietin-independent origin were present only in AT-3 mammary tumors. We further show that platelets influence the angiogenic and inflammatory profiles of AT-3 and B16F1 tumors, though with very different outcomes according to tumor type. Whereas thrombocytopenia increased bleeding in both tumor types, it further caused severe endothelial degeneration associated with massive vascular leakage, tumor swelling, and increased infiltration of cytotoxic cells, only in AT-3 tumors.

CONCLUSIONS

These results indicate that while platelets are integral components of solid tumors, their localization and origin in the TME, as well as their impact on its shaping, are tumor type-dependent.

Hemostasis without clot formation: how platelets guard the vasculature in inflammation, infection, and malignancy

Platelets are key vascular effectors in hemostasis, with activation signals leading to fast recruitment, aggregation, and clot formation. The canonical process of hemostasis is well-characterized and shares many similarities with pathological thrombus formation. However, platelets are also crucially involved in the maintenance of vascular integrity under both steady-state and inflammatory conditions by ensuring blood vessel homeostasis and preventing microbleeds. In these settings, platelets use distinct receptors, signaling pathways, and ensuing effector functions to carry out their deeds. Instead of simply forming clots, they mainly act as individual sentinels that swiftly adapt their behavior to the local microenvironment. In this review, we summarize previously recognized and more recent studies that have elucidated how anucleate, small platelets manage to maintain vascular integrity when faced with challenges of infection, sterile inflammation, and even malignancy. We dissect how platelets are recruited to the vascular wall, how they identify sites of injury, and how they prevent hemorrhage as single cells. Furthermore, we discuss mechanisms and consequences of platelets' interaction with leukocytes and endothelial cells, the relevance of adhesion as well as signaling receptors, in particular immunoreceptor tyrosine-based activation motif receptors, and cross talk with the coagulation system. Finally, we outline how recent insights into inflammatory hemostasis and vascular integrity may aid in the development of novel therapeutic strategies to prevent hemorrhagic events and vascular dysfunction in patients who are critically ill.

The role of platelets in the regulation of tumor growth and metastasis: the mechanisms and targeted therapy

Platelets are a class of pluripotent cells that, in addition to hemostasis and maintaining vascular endothelial integrity, are also involved in tumor growth and distant metastasis. The tumor microenvironment is a complex and comprehensive system composed of tumor cells and their surrounding immune and inflammatory cells, tumor-related fibroblasts, nearby interstitial tissues, microvessels, and various cytokines and chemokines. As an important member of the tumor microenvironment, platelets can promote tumor invasion and metastasis through various mechanisms. Understanding the role of platelets in tumor metastasis is important for diagnosing the risk of metastasis and prolonging survival. In this study, we more fully elucidate the underlying mechanisms by which platelets promote tumor growth and metastasis by modulating processes, such as immune escape, angiogenesis, tumor cell homing, and tumor cell exudation, and further summarize the effects of platelet-tumor cell interactions in the tumor microenvironment and possible tumor treatment strategies based on platelet studies. Our summary will more comprehensively and clearly demonstrate the role of platelets in tumor metastasis, so as to help clinical judgment of the potential risk of metastasis in cancer patients, with a view to improving the prognosis of patients.

The Progress of Platelets in Breast Cancer

Breast cancer is the most common female cancer and the sixth leading cause of death, seriously affecting the quality of life of women. Platelets, one of the fragments derived from megakaryocytes, are being increasingly investigated by tumor researchers because of their anticoagulant function. According to relevant studies, platelets, as the key source of circulating angiogenesis-related factors, can regulate tumor angiogenesis and vascular integrity, and they can also affect the tumor microenvironment, thereby facilitating the proliferation and differentiation of tumor cells. By covering or transferring normal MHC I molecules to tumor cells, platelets can protect tumor cells from being killed by the immune system and facilitate tumor cell metastasis. However, details on the mechanisms involved have remained elusive. This paper reviews and analyzes studies of the role of platelets in tumorigenesis, tumor cell proliferation, tumor metastasis, and cancer treatment to provide readers with a better understanding of the relevant studies.

Platelets and (Lymph)angiogenesis

The formation of new blood and lymphatic vessels is essential for both the development of multicellular organisms and (patho)physiological processes like wound repair and tumor growth. In the 1990s, circulating blood platelets were first postulated to regulate tumor angiogenesis by interacting with the endothelium and releasing angiogenic regulators from specialized α granules. Since then, many studies have validated the contributions of platelets to tumor angiogenesis, while uncovering novel roles for platelets in other angiogenic processes like wound resolution and retinal vascular disease. Although the majority of (lymph)angiogenesis occurs during development, platelets appear necessary for lymphatic but not vascular growth, implying their particular importance in pathological cases of adult angiogenesis. Future work is required to determine whether drugs targeting platelet production or function offer a clinically relevant tool to limit detrimental angiogenesis.

Add fuel to the fire: Inflammation and immune response in lung cancer combined with COVID-19

The corona virus disease 2019 (COVID-19) global pandemic has had an unprecedented and persistent impact on oncological practice, especially for patients with lung cancer, who are more vulnerable to the virus than the normal population. Indeed, the onset, progression, and prognosis of the two diseases may in some cases influence each other, and inflammation is an important link between them. The original chronic inflammatory environment of lung cancer patients may increase the risk of infection with COVID-19 and exacerbate secondary damage. Meanwhile, the acute inflammation caused by COVID-19 may induce tumour progression or cause immune activation. In this article, from the perspective of the immune microenvironment, the pathophysiological changes in the lungs and whole body of these special patients will be summarised and analysed to explore the possible immunological storm, immunosuppression, and immune escape phenomenon caused by chronic inflammation complicated by acute inflammation. The effects of COVID-19 on immune cells, inflammatory factors, chemokines, and related target proteins in the immune microenvironment of tumours are also discussed, as well as the potential role of the COVID-19 vaccine and immune checkpoint inhibitors in this setting. Finally, we provide recommendations for the treatment of lung cancer combined with COVID-19 in this special group.

Association of Systemic Immune Inflammation Index with All-Cause, Cardiovascular Disease, and Cancer-Related Mortality in Patients with Cardiovascular Disease: A Cross-Sectional Study

Objective

Our research was designed to investigate the relationship between systemic immune inflammation (SII) index and all-cause, cardiovascular disease (CVD), and cancer-related mortality in patients with CVD.

Methods

We used the National Health and Nutrition Examination Survey data from 1999 to 2018 to conduct this study. The association between SII index and all-cause, CVD, and cancer-related mortality in patients with CVD was examined using restricted cubic splines (RCS), Cox proportional hazard models, and subgroup analysis, respectively. CVD was defined as a composite of five outcomes of CVD, including coronary heart disease (CHD), congestive heart failure (CHF), angina pectoris, myocardial infarction, and stroke. Additionally, the link between SII index and all-cause, CVD, and cancer-related mortality in patients with a composite of five outcomes of CVD was also explored.

Results

In total, 5329 participants were included. The RCS also showed a U-curve correlation between SII index and the all-cause, CVD, and cancer-related mortality in patients with CVD. As compared with the individuals with lowest quartile of SII index, hazard ratios with 95% confidence intervals for all-cause, CVD, and cancer-related mortality across the quartiles were (1.202 (0.981, 1.474), 1.184 (0.967, 1.450), and 1.365 (1.115, 1.672)), (1.116 (0.815, 1.527), 1.017 (0.740, 1.398), and 1.220 (0.891, 1.670)), and (1.202 (0.981, 1.474), 1.184 (0.967, 1.450), and 1.365 (1.115, 1.672)), respectively, in the full-adjusted model. The SII index also had a U-shaped relationship with all-cause, CVD, and cancer-related mortality in patients with CHD, angina, and myocardial infarction. Additionally, the U-shaped relationship between SII index and all-cause, and cancer-related mortality also exists in CHF, and stroke. However, there was a positive linear correlation between SII index and CVD mortality in patients with CHF, and stroke.

Conclusion

In the United States general population, the correlation between SII index and all-cause, CVD, and cancer-related mortality showed a U-shaped curve in patients with CVD.

Association of the systemic immune-inflammation index with all-cause mortality in patients with arteriosclerotic cardiovascular disease

Objective

Systemic immune-inflammation index (SII), derived from blood cell counts of circulating platelets, neutrophils, and lymphocytes, has been identified as a novel inflammatory and prognostic marker. However, the clinical value of SII in patients with arteriosclerotic cardiovascular disease (ASCVD) had not been further explored. Thus, this study is designed to explore the associations of SII with mortality in ASCVD individuals.

Methods

All individuals with ASCVD aged ≥20 years were included from the National Health and Nutritional Examination Surveys (NHANES) 2005–2014 and followed for survival until 31 December 2019. Multivariable Cox analysis investigated the associations between SII, evaluated as a continuous variable with splines, as categorical ones (quartiles), and the all-cause death. To demonstrate the association between SII and mortality, subgroup analysis, restricted cubic spline along with piecewise linear regression were also conducted.

Results

A total of 2,595 participants (57.8% men) were included. During a median of 7.7 years of follow-up, 1,122 deaths due to all-cause were recorded. After adjusting for multiple confounders, when compared with the patients in quartile 1 (SII ln transform), those in quartile 4 had a 46% increased risk for all-cause death [hazard ratio (HR) = 1.46, 95% confidence interval (CI) = 1.22–1.75]. As a continuous variable, each unit of raised ln-SII was associated with a 24% increased risk of all-cause death (HR = 1.24, 95% CI = 1.10–1.38). In the restricted cubic spline regression model, the relationship between ln-SII and all-cause death was non-linear. The cutoff value of ln-SII for mortality was 6.57 and those with a higher than the threshold point had a 1.25-fold risk of mortality. No significant difference was noted below the threshold points.

Conclusion

An association was detected between the baseline ln-SII and all-cause mortality in a United States ASCVD population. Increased SII is associated with poor survival in individuals with ASCVD.

Impact of Platelets to Lymphocytes Ratio and Lymphocytes during Radical Concurrent Radiotherapy and Chemotherapy on Patients with Nonmetastatic Esophageal Squamous Cell Carcinoma

Purpose

This study examined the importance of hematological parameters as prognostic markers for people with esophageal cancer receiving radical concurrent chemoradiation.

Methods

106 patients with esophageal cancer are included in this study. Cox regression analysis, Kaplan-Meier method, and chi-square test were used to analyze our data.

Results

The median follow-up time for patients was 15.5 months (3-55). Univariate and multivariate analyses showed that age, the change of platelet-to-lymphocyte ratio (ΔPLR), and the change rate of circulating lymphocyte count (ΔCLC%) were independent influencing factors of OS and DFS. The patients were grouped according to the median of ΔPLR and ΔCLC%, and analysis showed that a higher ΔPLR and a higher ΔCLC% was related to poor OS and DFS (P < 0.001, P < 0.001 and P < 0.001, P < 0.001). By subgroup analysis, the OS of T1-4N1-2 were better in the low ΔPLR group than the high one (P = 0.03, P < 0.001, P = 0.001, P < 0.001, and P = 0.008). DFS of T3-4N1-2 in the low ΔPLR group were better than the high one (P < 0.001, P = 0.016 and P < 0.001, P = 0.022). For patients with T1-4N0-2, the OS in the low ΔCLC% group were better than in the high ΔCLC% group (P = 0.01, P < 0.001, P < 0.002, P = 0.012, P < 0.001, and P = 0.024). For T1-4N1-2, the DFS were better in the low ΔCLC% group than others (P = 0.042, P < 0.001, P < 0.001, P < 0.001, and P = 0.006).

Conclusion

ΔPLR and ΔCLC% are independent factors of OS and DFS, and a lower ΔPLR and ΔCLC% are associated with a better OS and DFS. And T3-4N1-2 patients in the low ΔPLR group and low ΔCLC% group have greater survival benefit.

Intratumoral Platelets: Harmful or Incidental Bystanders of the Tumor Microenvironment?

Simple Summary

The tumor microenvironment (TME) is the complex and heterogenous ecosystem of solid tumors known to influence their growth and their progression. Besides tumor cells, the TME comprises a variety of host-derived cell types, ranging from endothelial cells to fibroblasts and immune cells. Clinical and experimental data are converging to indicate that platelets, originally known for their fundamental hemostatic function, also participate in tumor development and shaping of the TME. Considering the abundance of antiplatelet drugs, understanding if and how platelets contribute to the TME may lead to new therapeutic tools for improved cancer prevention and treatments.

Abstract

The tumor microenvironment (TME) has gained considerable interest because of its decisive impact on cancer progression, response to treatment, and disease recurrence. The TME can favor the proliferation, dissemination, and immune evasion of cancer cells. Likewise, there is accumulating evidence that intratumoral platelets could favor the development and aggressiveness of solid tumors, notably by influencing tumor cell phenotype and shaping the vascular and immune TME components. Yet, in contrast to other tumor-associated cell types like macrophages and fibroblasts, platelets are still often overlooked as components of the TME. This might be due, in part, to a deficit in investigating and reporting the presence of platelets in the TME and its relationships with cancer characteristics. This review summarizes available evidence from clinical and animal studies supporting the notion that tumor-associated platelets are not incidental bystanders but instead integral and active components of the TME. A particular emphasis is given to the description of intratumoral platelets, as well as to the functional consequences and possible mechanisms of intratumoral platelet accumulation.

Procoagulant platelet sentinels prevent inflammatory bleeding through GPIIBIIIA and GPVI

Impairment of vascular integrity is a hallmark of inflammatory diseases. We recently reported that single immune-responsive platelets migrate and re-position themselves to sites of vascular injury to prevent bleeding. However, it remains unclear how single platelets preserve vascular integrity once encountering endothelial breaches. Here we demonstrate by intravital microscopy combined with genetic mouse models that procoagulant activation (PA) of single platelets and subsequent recruitment of the coagulation cascade are crucial for the prevention of inflammatory bleeding. Using a novel lactadherin-based compound we detect phosphatidylserine (PS)-positive procoagulant platelets in the inflamed vasculature. We identify exposed collagen as the central trigger arresting platelets and initiating subsequent PA in a CypD- and TMEM16F-dependent manner both in vivo and in vitro. Platelet PA promotes binding of the prothrombinase complex to the platelet membrane, greatly enhancing thrombin activity resulting in fibrin formation. PA of migrating platelets is initiated by co-stimulation via integrin αIIbβ3 (GPIIBIIIA)/Gα13-mediated outside-in-signaling and GPVI signaling, leading to an above-threshold intracellular calcium release. This effectively targets the coagulation cascade to breaches of vascular integrity identified by patrolling platelets. Platelet-specific genetic loss of either CypD or TMEM16F as well as combined blockade of platelet GPIIBIIIA and GPVI reduce platelet PA in vivo and aggravate pulmonary inflammatory hemorrhage. Our findings illustrate a novel role of procoagulant platelets in the prevention of inflammatory bleeding and provide evidence that PA of patrolling platelet sentinels effectively targets and confines activation of coagulation to breaches of vascular integrity.

Application of Regulatory Cell Death in Cancer: Based on Targeted Therapy and Immunotherapy

The development of cancer treatment methods is constantly changing. For common cancers, our treatment methods are still based on conventional treatment methods, such as chemotherapy, radiotherapy, and targeted drug therapy. Nevertheless, the emergence of tumor resistance has a negative impact on treatment. Regulated cell death is a gene-regulated mode of programmed cell death. After receiving specific signal transduction, cells change their physical and chemical properties and the extracellular microenvironment, resulting in structural destruction and decomposition. As research accumulates, we now know that by precisely inducing specific cell death patterns, we can treat cancer with less collateral damage than other treatments. Many newly discovered types of RCD are thought to be useful for cancer treatment. However, some experimental results suggest that some RCDs are not sensitive to cancer cell death, and some may even promote cancer progression. This review summarizes the discovered types of RCDs, reviews their clinical efficacy in cancer treatment, explores their anticancer mechanisms, and discusses the feasibility of some newly discovered RCDs for cancer treatment in combination with the immune and tumor microenvironment.

Assessment of Prognostic Value of Aspartate Aminotransferase-to-Platelet Ratio Index in Patients With Hepatocellular Carcinoma: Meta-Analysis of 28 Cohort Studies

Background: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors globally; it is valuable to predict its prognosis after treatment. Aspartate aminotransferase-to-platelet index (APRI), a non-invasive biomarker consists of two routine test parameters easily available in all the patients. Our study aimed to investigate whether APRI can serve as an independent prognostic marker in the patients with HCC.

Methods: We extensively searched PubMed, Embase, and Web of Science databases on June 20, 2021 to determine all relevant literature. The studies that explored the association between the APRI levels and prognosis of patients with HCC and reported risk estimate data were included. The Newcastle-Ottawa Scale was used to assess the quality of the included studies.

Results: A total of 1,097 articles were initially identified, of which 28 studies involving 11,041 patients met the eligibility criteria for the meta-analysis. The pooled hazard ratios (HRs) for overall survival (OS) and disease-free survival (DFS) were 1.77 (95% CI: 1.53–2.05, P < 0.001) and 1.59 (95% CI: 1.47–1.71, P < 0.001), respectively, suggesting a significant correlation between the increased APRI levels and poor prognosis in the patients with HCC. In the subgroup analyses, statistical significance of the correlation disappeared in the Korean and Japanese population and in the patients undergoing transarterial chemoembolization (TACE). Of note, the current results may be overestimated due to publication bias, but the conclusion remained unchanged when the bias was adjusted.

Conclusion: High APRI levels are associated with poor OS and DFS in the patients with HCC. In most cases, pretreatment APRI can be used as an independent prognostic factor, but it is necessary to incorporate other predictive prognostic systems to ensure accuracy. Further studies are needed to determine the specific beneficiary population and the optimal cutoff value.

Role of Cell-Free DNA and Deoxyribonucleases in Tumor Progression

Many studies have reported an increase in the level of circulating cell-free DNA (cfDNA) in the blood of patients with cancer. cfDNA mainly comes from tumor cells and, therefore, carries features of its genomic profile. Moreover, tumor-derived cfDNA can act like oncoviruses, entering the cells of vulnerable organs, transforming them and forming metastatic nodes. Another source of cfDNA is immune cells, including neutrophils that generate neutrophil extracellular traps (NETs). Despite the potential eliminative effect of NETs on tumors, in some cases, their excessive generation provokes tumor growth as well as invasion. Considering both possible pathological contributions of cfDNA, as an agent of oncotransformation and the main component of NETs, the study of deoxyribonucleases (DNases) as anticancer and antimetastatic agents is important and promising. This review considers the pathological role of cfDNA in cancer development and the role of DNases as agents to prevent and/or prohibit tumor progression and the development of metastases.

Platelet-Cancer Interplay: Molecular Mechanisms and New Therapeutic Avenues

Although platelets are critically involved in thrombosis and hemostasis, experimental and clinical evidence indicate that platelets promote tumor progression and metastasis through a wide range of physical and functional interactions between platelets and cancer cells. Thrombotic and thromboembolic events are frequent complications in patients with solid tumors. Hence, cancer modulates platelet function by directly inducing platelet-tumor aggregates and triggering platelet granule release and altering platelet turnover. Also, platelets enhance tumor cell dissemination by activating endothelial cell function and recruiting immune cells to primary and metastatic tumor sites. In this review, we summarize current knowledge on the complex interactions between platelets and tumor cells and the host microenvironment. We also critically discuss the potential of anti-platelet agents for cancer prevention and treatment.

Histone citrullination: a new target for tumors

As the main protein components of chromatin, histones play central roles in gene regulation as spools of winding DNA. Histones are subject to various modifications, including phosphorylation, acetylation, glycosylation, methylation, ubiquitination and citrullination, which affect gene transcription. Histone citrullination, a posttranscriptional modification catalyzed by peptidyl arginine deiminase (PAD) enzymes, is involved in human carcinogenesis. In this study, we highlighted the functions of histone citrullination in physiological regulation and tumors. Additionally, because histone citrullination involves forming neutrophil extracellular traps (NETs), the relationship between NETs and tumors was illustrated. Finally, the clinical application of histone citrullination and PAD inhibitors was discussed.

Targeting platelet function to improve drug delivery

Thrombocytopenia-induced tumor hemorrhage improves drug delivery to tumors. This phenomenon presents a new way to increase drug efficacy with minimal side effects. Combining anti-platelet treatment with therapeutic drugs may help us in the search for more effective ways to fight cancer.

Platelet-Derived GARP Induces Peripheral Regulatory T Cells-Potential Impact on T Cell Suppression in Patients with Melanoma-Associated Thrombocytosis

Platelets have been recently described as an important component of the innate and adaptive immunity through their interaction with immune cells. However, information on the platelet-T cell interaction in immune-mediated diseases remains limited. Glycoprotein A repetitions predominant (GARP) expressed on platelets and on activated regulatory T cells (Treg) is involved in the regulation of peripheral immune responses by modulating the bioavailability of transforming growth factor β (TGF-β). Soluble GARP (sGARP) exhibits strong regulatory and anti-inflammatory capacities both in vitro and in vivo, leading to the induction of peripheral Treg. Herein, we investigated the effect of platelet-derived GARP on the differentiation, phenotype, and function of T effector cells. CD4⁺CD25^- T cells cocultured with platelets upregulated FoxP3, the master transcription factor for Treg, were anergic, and were strongly suppressive. These effects were reversed by using a blocking anti-GARP antibody, indicating a dependency on GARP. Importantly, melanoma patients in different stages of disease showed a significant upregulation of GARP on the platelet surface, correlating to a reduced responsiveness to immunotherapy. In conclusion, our data indicate that platelets induce peripheral Treg via GARP. These findings might contribute to diseases such as cancer-associated thrombocytosis, wherein poor prognosis and metastasis are associated with high counts of circulating platelets.

Pre-radiotherapy lymphocyte count and platelet-to-lymphocyte ratio may improve survival prediction beyond clinical factors in limited stage small cell lung cancer: model development and validation

Background

Few small sample size studies have reported lymphocyte count was prognostic for survival in small-cell lung cancer (SCLC). This study aimed to validate this finding, to build prediction model for overall survival (OS) and to study whether novel models that combine lymphocyte-related variables can predict OS more accurately than a conventional model using clinical factors alone in a large cohort of limited-stage SCLC patients.

Methods

This study enrolled 544 limited-stage SCLC patients receiving definitive chemo-radiation with pre-radiotherapy lymphocyte-related variables including absolute lymphocyte count (ALC), platelet-to-lymphocyte ratio (P/L ratio), neutrophil-to-lymphocyte ratio (N/L ratio), and lymphocyte-to-monocyte ratio (L/M ratio). The primary endpoint was OS. These patients were randomly divided into a training dataset (n=274) and a validation dataset (n=270). Multivariate survival models were built in the training dataset, and the performance of these models were further tested in the validation dataset using the concordance index (C-index).

Results

The median follow-up time was 36 months for all patients. In the training dataset, univariate analysis showed that ALC (P=0.020) and P/L ratio (P=0.023) were significantly correlated with OS, while L/M ratio (P=0.091) and N/L ratio (P=0.436) were not. Multivariate modeling demonstrated the significance of ALC (P=0.063) and P/L ratio (P=0.003), and the improvement for OS prediction in combined models with the addition of ALC (C-index =0.693) or P/L ratio (C-index =0.688) over the conventional model (C-index =0.679). The validation dataset analysis confirmed a modest improvement of C-index with the addition of ALC or P/L ratio. All these models showed reasonable discriminations and calibrations.

Conclusions

This study validated the significant value of pre-radiotherapy ALC and P/L ratio on OS in limited-stage SCLC. The combined model with ALC or P/L ratio showed additional OS prediction values than the conventional model with clinical factors alone.

Platelet count as a biomarker for monitoring treatment response and disease recurrence in recurrent epithelial ovarian cancer

OBJECTIVES

We sought to determine the impact of pretreatment plasma platelet levels, dimerized plasmin fragment (D-dimer) and fibrinogen in recurrent epithelial ovarian cancer (EOC) and the impact of platelet levels on SKOV3 cell lines growth and responsiveness to chemotherapy.

METHODS

Under approval of ethical committee, we identified 104 women with recurrent EOC who underwent treatment between January 2010 and February 2015. Reviewing clinical, laboratory, and pathologic records from this retrospective cohort, we analyzed the correlation between pretreatment plasma D-dimer, fibrinogen, platelet levels and clinicopathological parameters, progression free survival (PFS) and overall survival (OS). Inco-culture experiments human ovarian cancer SKOV3 cell lines were used to test the effect of platelet levels on tumor growth and responsiveness to docetaxel.

RESULTS

Of the 104 recurrent EOC, thrombocytosis at diagnosis and the decrease of platelet count by less than 25% after primary therapy were associated with worse median progression free survival (P = 0.003;P = 0.021) and median overall survival (P = 0.009;P = 0.009). Mean platelet levels declined at the end of primary therapy(P < 0.001) and rose at recurrence(P = 0.007). In multivariate analysis, elevated platelet levels at primary therapy and the decrease of platelet count less than 25% after primary therapy were unfavorable prognostic factor for PFS(P = 0.022; P = 0.015) and OS(P = 0.013;P = 0.007) in recurrent EOC, but elevated plasma D-dimer and fibrinogen were not. In SKOV-3 ovarian cancer cell lines, suitable concentration platelet co-culture protected against apoptosis (P < 0.05).

CONCLUSIONS

Platelet count during treatment could be used as a biomarker used for monitoring the disease recurrence and predicting treatment response. And platelet with suitable concentration co-culture protected against apoptosis in SKOV3 cell line, which may explain clinical observations.

The endothelial barrier and cancer metastasis: Does the protective facet of platelet function matter?

Overwhelming evidence suggests that platelets have a detrimental role in promoting cancer spread via platelet-cancer cell interactions linked to thrombotic mechanisms. On the other hand, a beneficial role of platelets in the preservation of the endothelial barrier in inflammatory conditions has been recently described, a phenomenon that could also operate in cancer-related inflammation. It is tempting to speculate that some antiplatelet strategies to combat cancer metastasis may impair the endogenous platelet-dependent mechanisms preserving endothelial barrier function. If the protective function of platelets is impaired, it may lead to increased endothelial permeability and more efficient cancer cell intravasation in the primary tumor and cancer cell extravasation at metastatic sites. In this commentary, we discuss current evidence that could support this hypothesis.

The reversed passive Arthus reaction as a model for investigating the mechanisms of inflammation-associated hemostasis

In recent years, accumulating evidence has indicated that platelets continuously repair vascular damage at sites of inflammation and/or infection. Studies in mouse models of inflammation have highlighted the fact that the mechanisms underlying bleeding prevention by platelets in inflamed organs can substantially differ from those supporting primary hemostasis following tail tip transection or thrombus formation in models of thrombosis. As a consequence, exploration of the hemostatic function of platelets in inflammation, as well as assessment of the risk of inflammation-induced bleeding associated with a platelet deficit and/or the use of anti-thrombotic drugs, require the use of dedicated experimental models. In the present review, we present the pros and cons of the cutaneous reversed passive Arthus reaction, a model of inflammation which has been instrumental in studying how inflammation causes vascular injury and how platelets continuously intervene to repair it. The limitations and common issues encountered when working with mouse models of inflammation for investigating platelet functions in inflammation are also discussed.

Comparison of Hematologic and Other Prognostic Markers in Metastatic Colorectal Cancer

BACKGROUND

Associations of thrombocytosis, neutrophilia, and lymphopenia with prognosis have been confirmed in many cancers. This study aims at comparing various prognostic indices based on blood counts in metastatic colorectal adenocarcinomas.

PATIENTS AND METHODS

Records from 152 patients with metastatic colorectal cancer who were treated in our center were reviewed. Demographic and disease characteristics and hematologic parameters data were extracted and patients were stratified according to their scores of several hematologic ratios. Hematologic ratios and parameters considered included the platelet-neutrophil to lymphocyte ratio (PNLR), the platelet to lymphocyte ratio (PLR), the neutrophil to lymphocyte ratio (NLR), the Abnormal Hematological Markers Index (AHMI), and the neutrophil-platelet score (NPS). Optimal cutoffs were defined with the aid of an online tool. Baseline parameters of the two groups derived for each tool were evaluated and compared with the χ² test. Univariate and multivariate Cox proportional-hazards regression analyses were performed on variables of interest.

RESULTS

Progression-Free Survival (PFS) hazard ratios (HR) between the high-risk and low-risk groups derived from the multivariate analyses for each index were as follows: for PNLR 2.0 (95% CI 1.28-3.13), for PLR 1.74 (95% CI 1.13-2.67), for NLR 1.54 (95% CI 1.04-2.29), for AHMI 1.62 (95% CI 1.06-2.46), and for NPS 1.47 (95% CI 1.1-1.96). Overall Survival (OS) hazard ratios (HR) derived from the multivariate analyses for each index were as follows: for PNLR 2.23 (95% CI 1.36-3.66), for PLR 1.68 (95% CI 1.03-2.75), for NLR 1.62 (95% CI 1.06-2.49), for AHMI 1.7 (95% CI 1.07-2.69), and for NPS 1.53 (95% CI 1.11-2.11). Another prognostic index called PRONOPALL, which is based on ECOG PS (0-1 versus 2-3 versus 4), number of metastatic sites (≤ 1 versus ≥ 2), LDH (< 600 U/L versus ≥ 600 U/L), and albumin (≥ 33 g/L versus < 33 g/L), had HRs of 1.75 and 2.20 for PFS and OS, respectively, with a cutoff of < 4 versus ≥ 4. This score has a range of 0 to 10 and points are attributed for the presence of each of the four prognostic factors.

CONCLUSION

In this analysis of metastatic colorectal cancer patients, several ratios and other prognostic tools had prognostic value for both OS and PFS. While other variables held significance for poorer prognosis, PNLR had the highest HR and the highest significance in multivariate analysis for both PFS and OS. Thus, it represents a valid prognostic tool in metastatic colorectal cancer among the spectrum of hematologic parameter-constructed tools.

Neutrophil Elastase and Neutrophil Extracellular Traps in the Tumor Microenvironment

Tumor-associated neutrophils (TANs) play a major role during cancer development and progression in the tumor microenvironment. Neutrophil elastase (NE) is a serine protease normally expressed in neutrophil primary granules. Formation of neutrophil extracellular traps (NETs), a mechanism used by neutrophils, has been traditionally associated with the capture and killing of bacteria. However, there are recent discoveries suggesting that NE secretion and NETs formation are also involved in the tumor microenvironment. Here, we focus on how NE and NETs play a key regulatory function in the tumor microenvironment, such as tumor proliferation, distant metastasis, tumor-associated thrombosis, and antitumor activity. Additionally, the potential use of NETs, NE, or associated molecules as potential disease activity biomarkers or therapeutic targets will be introduced.

The pro-tumor effect and the anti-tumor effect of neutrophils extracellular traps

Significant advances in our understanding of neutrophil biology were made in the past several years. A newly discovered mechanism was discovered, the formation of neutrophils extracellular traps (NETs). The structure of NETs is composed of the DNA strand and neutrophil granule proteins. NETs were found to have an association with tumor progression. This review highlights the latest knowledge about the controversial effect on tumors of NETs. Pro-tumor and anti-tumor effects are described respectively. The probable mechanisms of the anti-tumor effect are related to its direct killing of cancer cells or stimulation of the immune system to fight against the tumor. The pro-tumor effect has a correlation with matrix metalloproteinase 9 (MMP-9), cathepsin G, and neutrophil elastase (NE). Moreover, the structure of the NETs makes it able to catch the circulating tumor cells, which could lead to metastasis. This review summarizes our knowledge about the proven roles of NETs in the progression of cancer with particular focus on the components of the NETs, and considers NETs as a potential target for cancer therapy.

Extracellular DNA NET-Works With Dire Consequences for Health

Neutrophils play a central role in innate immune defense. Advances in neutrophil biology have brought to light the capacity of neutrophils to release their decondensed chromatin and form large extracellular DNA networks called neutrophil extracellular traps (NETs). NETs are produced in response to many infectious and noninfectious stimuli and, together with fibrin, block the invasion of pathogens. However, their formation in inflamed blood vessels produces a scaffold that supports thrombosis, generates neo-antigens favoring autoimmunity, and aggravates damage in ischemia/reperfusion injury. NET formation can also be induced by cancer and promotes tumor progression. Formation of NETs within organs can be immediately detrimental, such as in lung alveoli, where they affect respiration, or they can be harmful over longer periods of time. For example, NETs initiate excessive deposition of collagen, resulting in fibrosis, thus likely contributing to heart failure. Here, we summarize the latest knowledge on NET generation and discuss how excessive NET formation mediates propagation of thrombosis and inflammation and, thereby, contributes to various diseases. There are many ways in which NET formation could be averted or NETs neutralized to prevent their detrimental consequences, and we will provide an overview of these possibilities.

Platelet-Based Drug Delivery for Cancer Applications

Platelets can be considered as the "guardian of hemostasis" where their main function is to maintain vascular integrity. In pathological conditions, the hemostatic role of platelets may be hijacked to stimulate disease progression. In 1865, Armand Trousseau was a pioneer in establishing the platelet-cancer metastasis relationship, which he eventually termed as Trousseau's Syndrome to describe the deregulation of the hemostasis-associated pathways induced by cancer progression (Varki, Blood. 110(6):1723-9, 2007). Since these early studies, there has been an increase in experimental evidence not only to elucidate the role of platelets in cancer metastasis but also to create novel cancer therapies by targeting the platelet's impact in metastasis. In this chapter, we discuss the contribution of platelets in facilitating tumor cell transit from the primary tumor to distant metastatic sites as well as novel cancer therapies based on platelet interactions.

Inhibition of platelet GPVI induces intratumor hemorrhage and increases efficacy of chemotherapy in mice

Maintenance of tumor vasculature integrity is indispensable for tumor growth and thus affects tumor progression. Previous studies have identified platelets as major regulators of tumor vascular integrity, as their depletion selectively rendered tumor vessels highly permeable and caused massive intratumoral hemorrhage. While these results established platelets as potential targets for antitumor therapy, their depletion is not a treatment option due to their essential role in hemostasis. Thus, a detailed understanding of how platelets safeguard vascular integrity in tumors is urgently demanded. Here, we show for the first time that functional inhibition of glycoprotein VI (GPVI) on the platelet surface with an antibody (JAQ1) F(ab)₂ fragment rapidly induces tumor hemorrhage and diminishes tumor growth similar to complete platelet depletion while not inducing systemic bleeding complications. The intratumor bleeding and tumor growth arrest could be reverted by depletion of Ly6G⁺ cells, confirming them to be responsible for the induction of bleeding and necrosis within the tumor. In addition, JAQ1 F(ab)₂-mediated GPVI inhibition increased intratumoral accumulation of coadministered chemotherapeutic agents, such as Doxil and paclitaxel, thereby resulting in a profound antitumor effect. In summary, our findings identify platelet GPVI as a key regulator of vascular integrity specifically in growing tumors and could serve as a basis for the development of antitumor strategies based on the interference with platelet function.

Spontaneous bleeding in thrombocytopenia: Is it really spontaneous?

Spontaneous bleeding is a clinical hallmark of thrombocytopenia and can take multiple forms including petechiae, epistaxis, gum bleeding, or, in worst cases, intracranial hemorrhage. Those bleeding events are called " spontaneous " because they occur in the absence of overt trauma. Spontaneous bleeding manifestations have long been considered to be a direct consequence of low platelet counts. Nevertheless, although low platelet counts may lead to ultrastructural endothelial alterations, those alterations and the associated state of vascular fragility are unlikely sufficient to cause spontaneous rupture of the microvessel wall. Indeed, in addition to endothelial injury, factors capable of damaging the basement membrane are required to allow escape of red blood cells in the extravascular space. Therefore, despite their misleading name, spontaneous bleeding events in thrombocytopenia are most likely provoked and involve subclinical biological processes in which platelets normally intervene to ensure hemostasis. In this review, we discuss past and more recent studies on the possible triggers of spontaneous bleeding events in thrombocytopenia, with a particular focus on the role of inflammatory reactions.

Peptidylarginine deiminase 4: a nuclear button triggering neutrophil extracellular traps in inflammatory diseases and aging

Peptidylarginine deiminase 4 (PAD4) is a nuclear citrullinating enzyme that is critically involved in the release of decondensed chromatin from neutrophils as neutrophil extracellular traps (NETs). NETs, together with fibrin, are implicated in host defense against pathogens; however, the formation of NETs (NETosis) has injurious effects that may outweigh their protective role. For example, PAD4 activity produces citrullinated neoantigens that promote autoimmune diseases, such as rheumatoid arthritis, to which PAD4 is genetically linked and where NETosis is prominent. NETs are also generated in basic sterile inflammatory responses that are induced by many inflammatory stimuli, including cytokines, hypoxia, and activated platelets. Mice that lack PAD4-deficient in NETosis-serve as an excellent tool with which to study the importance of NETs in disease models. In recent years, animal and human studies have demonstrated that NETs contribute to the etiology and propagation of many common noninfectious diseases, the focus of our review. We will discuss the role of NETs in thrombotic and cardiovascular disease, the induction of NETs by cancers and its implications for cancer progression and cancer-associated thrombosis, and elevated NETosis in diabetes and its negative impact on wound healing, and will propose a link between PAD4/NETs and age-related organ fibrosis. We identify unresolved issues and new research directions.-Wong, S. L., Wagner, D. D. Peptidylarginine deiminase 4: a nuclear button triggering neutrophil extracellular traps in inflammatory diseases and aging.

The Platelet Lifeline to Cancer: Challenges and Opportunities

Besides their function in limiting blood loss and promoting wound healing, experimental evidence has highlighted platelets as active players in all steps of tumorigenesis including tumor growth, tumor cell extravasation, and metastasis. Additionally, thrombocytosis in cancer patients is associated with adverse patient survival. Due to the secretion of large amounts of microparticles and exosomes, platelets are well positioned to coordinate both local and distant tumor-host crosstalk. Here, we present a review of recent discoveries in the field of platelet biology and the role of platelets in cancer progression as well as challenges in targeting platelets for cancer treatment.

The platelets-neutrophils to lymphocytes ratio: a new prognostic marker in metastatic colorectal cancer

Background

The cancer micro-environment is recognized as having an increasing importance in cancer progression. Immune cells originating from the peripheral blood are important elements of this environment. Thrombocytosis, neutrophilia and lymphocytopenia have been found to be negative prognostic indicators in many cancers. This study aims to evaluate the potential of the use of a novel hematological marker, the platelet-neutrophil to lymphocyte ratio (PNLR) as a practical, reliable, and inexpensive prognostic tool in metastatic colorectal adenocarcinomas.

Methods

Charts from 305 patients with colorectal cancer were retrospectively reviewed. Of these, 152 had metastatic disease with complete follow-up data on progression and survival. Data were extracted and stratified by a PNLR cut-off point of 2,000. Baseline parameters of the two groups were evaluated and compared with the χ² test. Univariate and multivariate Cox proportional-hazards regression analyses were performed on variables of interest.

Results

A total of 102 (67.1%) patients had a PNLR of less than 2,000 while the index for 50 (32.9%) patients was 2,000 or higher. Patients with a PNLR above 2,000 had a shorter median progression-free survival (PFS) [6.5 vs. 13.3 months; hazard ratio (HR), 2.05; 95% CI, 1.32-3.19, P=0.001] than in patients with a PNLR below the threshold. Similar results were observed for median overall survival (OS) (9.6 vs. 21.8 months; HR, 2.33; 95% CI, 1.44-3.79, P=0.001). PNLR had a higher predictive HR than Eastern Cooperative Oncology Group (ECOG) performance status (PS).

Conclusions

In this retrospective analysis of metastatic colorectal cancer patients, PNLR had prognostic value for both OS and PFS. While other variables held significance for poorer prognosis, PNLR had the highest HR and the highest significance in multivariate analysis for both PFS and OS. Thus, it represents a powerful and objective prognostic tool in the evaluation of metastatic colorectal cancer patients that is readily available and does not require any additional expenses.

Glycoprotein VI in securing vascular integrity in inflamed vessels

Glycoprotein VI (GPVI), the main platelet receptor for collagen, has been shown to play a central role in various models of thrombosis, and to be a minor actor of hemostasis at sites of trauma. These observations have made of GPVI a novel target for antithrombotic therapy, as its inhibition would ideally combine efficacy with safety. Nevertheless, recent studies have indicated that GPVI could play an important role in preventing bleeding caused by neutrophils in the inflamed skin and lungs. Remarkably, there is evidence that the GPVI-dependent hemostatic function of platelets at the acute phase of inflammation in these organs does not involve aggregation. From a therapeutic perspective, the vasculoprotective action of GPVI in inflammation suggests that blocking of GPVI might bear some risks of bleeding at sites of neutrophil infiltration. In this review, we summarize recent findings on GPVI functions in inflammation and discuss their possible clinical implications and applications.

CLEC1B Expression and PD-L1 Expression Predict Clinical Outcome in Hepatocellular Carcinoma with Tumor Hemorrhage

Spontaneous tumor hemorrhage (TH) is frequently observed in solid tumors including human hepatocellular carcinoma (HCC). TH implies fast-growing and worse tumor immunological microenvironment; however, the underlying mechanism remains largely unknown. CLEC1B is a signature gene highly associated with tumor progression. PD-L1 expression is a key biomarker predictive of immune checkpoint therapies, which showed astonishing effect on various types of tumor. We assume that, in HCC, TH may closely associate with the expression of these two molecules. In this study, 136 patients with HCC were enrolled. qRT-PCR showed that CLEC1B expression is significantly lower in HCC tumor tissue. Immunohistochemistry of HCC tissue microarrays demonstrated that PD-L1_high and CLEC1B_low expressions were significantly correlated with TH and clinicopathological features indicating worse HCC progression. According to univariate/multivariate analysis, a combination of PD-L1_high and CLEC1B_low expression was an independent prognostic factor indicating the poor outcome. The prognostic value of PD-L1_high and CLEC1B_low was validated by Cox proportional-hazard analyses. Collectively, tumor with TH is closely associated with CLEC1B_low & PD-L1_high expression, which may imply high response of PD-L1/PD-1 immune checkpoint therapies. CLEC1B may be a potential therapeutic target for PD-L1/PD-1 immunotherapy. PD-L1_high and CLEC1B_low can be a valuable prognosis factor implying worse clinical outcomes.

Platelets and vascular integrity: how platelets prevent bleeding in inflammation

Platelets play a central role in primary hemostasis by forming aggregates that plug holes in injured vessels. Half a century ago, detailed studies of the microvasculature by electron microscopy revealed that under inflammatory conditions that do not induce major disruption to vascular structure, individual platelets are mobilized to the vessel wall, where they interact with leukocytes and appear to seal gaps that arise between endothelial cells. Recent developments in genetic engineering and intravital microscopy have allowed further molecular and temporal characterization of these events. Surprisingly, it turns out that platelets support the recruitment of leukocytes to sites of inflammation. In parallel, however, they exercise their hemostatic function by securing the integrity of inflamed blood vessels to prevent bleeding from sites of leukocyte infiltration. It thus appears that platelets not only serve in concert as building blocks of the hemostatic plug but also act individually as gatekeepers of the vascular wall to help preserve vascular integrity while coordinating host defense. Variants of this recently appreciated hemostatic function of platelets that we refer to as "inflammation-associated hemostasis" are engaged in different contexts in which the endothelium is challenged or dysfunctional. Although the distinguishing characteristics of these variants and the underlying mechanisms of inflammation-associated hemostasis remain to be fully elucidated, they can differ notably from those supporting thrombosis, thus presenting therapeutic opportunities.

Endothelial alterations in a canine model of immune thrombocytopenia

Bleeding heterogeneity amongst patients with immune thrombocytopenia (ITP) is poorly understood. Platelets play a role in maintaining endothelial integrity, and variable thrombocytopenia-induced endothelial changes may influence bleeding severity. Platelet-derived endothelial stabilizers and markers of endothelial integrity in ITP are largely underexplored. We hypothesized that, in a canine ITP model, thrombocytopenia would lead to alterations in the endothelial ultrastructure and that the Von Willebrand factor (vWF) would serve as a marker of endothelial injury associated with thrombocytopenia. Thrombocytopenia was induced in healthy dogs with an antiplatelet antibody infusion; control dogs received an isotype control antibody. Cutaneous biopsies were obtained prior to thrombocytopenia induction, at platelet nadir, 24 hours after nadir, and on platelet recovery. Cutaneous capillaries were assessed by electron microscopy for vessel thickness, the number of pinocytotic vesicles, the number of large vacuoles, and the number of gaps between cells. Pinocytotic vesicles are thought to represent an endothelial membrane reserve that can be used for repair of damaged endothelial cells. Plasma samples were assessed for vWF. ITP dogs had significantly decreased pinocytotic vesicle numbers compared to control dogs (P = 0.0357) and the increase in plasma vWF from baseline to 24 hours correlated directly with the endothelial large vacuole score (R = 0.99103; P < 0.0001). This direct correlation between plasma vWF and the number of large vacuoles, representing the vesiculo-vacuolar organelle (VVO), a permeability structure, suggests that circulating vWF could serve as a biomarker for endothelial alterations and potentially a predictor of thrombocytopenic bleeding. Overall, our results indicate that endothelial damage occurs in the canine ITP model and variability in the degree of endothelial damage may account for differences in the bleeding phenotype among patients with ITP.

Phosphatidylinositol transfer protein-α in platelets is inconsequential for thrombosis yet is utilized for tumor metastasis

Platelets are increasingly recognized for their contributions to tumor metastasis. Here, we show that the phosphoinositide signaling modulated by phosphatidylinositol transfer protein type α (PITPα), a protein which shuttles phosphatidylinositol between organelles, is essential for platelet-mediated tumor metastasis. PITPα-deficient platelets have reduced intracellular pools of phosphoinositides and an 80% reduction in IP₃ generation upon platelet activation. Unexpectedly, mice lacking platelet PITPα form thrombi normally at sites of intravascular injuries. However, following intravenous injection of tumor cells, mice lacking PITPα develop fewer lung metastases due to a reduction of fibrin formation surrounding the tumor cells, rendering the metastases susceptible to mucosal immunity. These findings demonstrate that platelet PITPα-mediated phosphoinositide signaling is inconsequential for in vivo hemostasis, yet is critical for in vivo dissemination. Moreover, this demonstrates that signaling pathways within platelets may be segregated into pathways that are essential for thrombosis formation and pathways that are important for non-hemostatic functions.

The Potential Role of Senescence As a Modulator of Platelets and Tumorigenesis

In addition to thrombus formation, alterations in platelet function are frequently observed in cancer patients. Importantly, both thrombus and tumor formation are influenced by age, although the mechanisms through which physiological aging modulates these processes remain poorly understood. In this context, the potential effects of senescent cells on platelet function represent pathophysiological mechanisms that deserve further exploration. Cellular senescence has traditionally been viewed as a barrier to tumorigenesis. However, far from being passive bystanders, senescent cells are metabolically active and able to secrete a variety of soluble and insoluble factors. This feature, known as the senescence-associated secretory phenotype (SASP), may provide senescent cells with the capacity to modify the tissue environment and, paradoxically, promote proliferation and neoplastic transformation of neighboring cells. In fact, the SASP-dependent ability of senescent cells to enhance tumorigenesis has been confirmed in cellular systems involving epithelial cells and fibroblasts, leaving open the question as to whether similar interactions can be extended to other cellular contexts. In this review, we discuss the diverse functions of platelets in tumorigenesis and suggest the possibility that senescent cells might also influence tumorigenesis through their ability to modulate the functional status of platelets through the SASP.

An emerging role for neutrophil extracellular traps in noninfectious disease

The production of neutrophil extracellular traps (NETs) is a process that enables neutrophils to help catch and kill bacteria. However, increasing evidence suggests that this process might also occur in noninfectious, sterile inflammation. In this Review, we describe the role of NETosis in autoimmunity, coagulation, acute injuries and cancer, and discuss NETs as potential therapeutic targets. Furthermore, we consider whether extracellular DNA is always detrimental in sterile inflammation and whether the source is always NETs.

Pre-treatment platelet counts as a prognostic and predictive factor in stage II and III rectal adenocarcinoma

AIM

To investigate if pre-treatment platelet counts could provide prognostic information in patients with rectal adenocarcinoma that received neo-adjuvant treatment.

METHODS

Platelet number on diagnosis of stage II and III rectal cancer was evaluated in 51 patients receiving neo-adjuvant treatment and for whom there were complete follow-up data on progression and survival, as well as pathologic outcome at the time of surgery. Pathologic responses on the surgical specimen of patients with lower platelet counts (150-300 × 10⁹/L) were compared with these of patients with higher platelet counts (> 300 × 10⁹/L) by the χ² test. Overall and progression free survival Kaplan-Meier curves of the two groups were constructed and compared with the Log-Rank test.

RESULTS

A significant difference was present between the two groups in regards to pathologic response with patients with lower platelet counts being more likely to exhibit a good or complete response to neo-adjuvant treatment than patients with higher platelet counts (P = 0.015). Among other factors evaluated, there was also a significant difference between the carcinoembryonic antigen (CEA) at presentation of patients that exhibited a good or complete response and those that had no response or a minimal to moderate response. Patients with a good or complete response were more likely to present with a CEA of less than 5 μg/L (P = 0.00066). There was no significant difference in overall and progression free survival between the two platelet count groups (Log-Rank tests P = 0.42 and P = 0.35, respectively).

CONCLUSION

In this retrospective analysis of stage II and III rectal cancer patients, platelet counts at the time of diagnosis had prognostic value for neo-adjuvant treatment pathologic response. Pre-treatment CEA also held prognostic value in regards to treatment effect.

NETopathies? Unraveling the Dark Side of Old Diseases through Neutrophils

Neutrophil extracellular traps (NETs) were initially described as an antimicrobial mechanism of neutrophils. Over the last decade, several lines of evidence support the involvement of NETs in a plethora of pathological conditions. Clinical and experimental data indicate that NET release constitutes a shared mechanism, which is involved in a different degree in various manifestations of non-infectious diseases. Even though the backbone of NETs is similar, there are differences in their protein load in different diseases, which represent alterations in neutrophil protein expression in distinct disorder-specific microenvironments. The characterization of NET protein load in different NET-driven disorders could be of significant diagnostic and/or therapeutic value. Additionally, it will provide further evidence for the role of NETs in disease pathogenesis, and it will enable the characterization of disorders in which neutrophils and NET-dependent inflammation are of critical importance.

The Dual Role of Neutrophils in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are characterised by aberrant immunological responses leading to chronic inflammation without tissue regeneration. These two diseases are considered distinct entities, and there is some evidence that neutrophil behaviour, above all other aspects of immunity, clearly separate them. Neutrophils are the first immune cells recruited to the site of inflammation, and their action is crucial to limit invasion by microorganisms. Furthermore, they play an essential role in proper resolution of inflammation. When these processes are not tightly regulated, they can trigger positive feedback amplification loops that promote neutrophil activation, leading to significant tissue damage and evolution toward chronic disease. Defective chemotaxis, as observed in Crohn’s disease, can also contribute to the disease through impaired microbe elimination. In addition, through NET production, neutrophils may be involved in thrombo-embolic events frequently observed in IBD patients. While the role of neutrophils has been studied in different animal models of IBD for many years, their contribution to the pathogenesis of IBD remains poorly understood, and no molecules targeting neutrophils are used and validated for the treatment of these pathologies. Therefore, it is crucial to improve our understanding of their mode of action in these particular conditions in order to provide new therapeutic avenues for IBD.

Neutrophil extracellular traps: protagonists of cancer progression?

Neutrophil extracellular traps (NETs) are a defense mechanism first described to trap and kill bacteria and other pathogens. Increasingly, however, their involvement in the pathogenesis of inflammatory and malignant diseases is being recognized. Several recent studies have suggested important roles of NETs in tumor progression, metastasis and tumor-associated thrombosis. Although systematic studies to address the role of NETs in tumor development are still scarce, we will explore the emerging evidence for NETs as potential protagonists in malignant disease and highlight the mechanisms through which these effects may be exerted. Future questions arising from our current knowledge of direct and indirect interactions between NETs and cancer cells will be outlined and we will explore NETs as candidate pharmaceutical targets in cancer patients.

New Insights into Neutrophil Extracellular Traps: Mechanisms of Formation and Role in Inflammation

Recent data suggest that NETosis plays a crucial role in the innate immune response and disturbs the homeostasis of the immune system. NETosis is a form of neutrophil-specific cell death characterized by the release of large web-like structures referred to as neutrophil extracellular traps (NETs). NETs are composed of DNA strands associated with histones and decorated with about 20 different proteins, including neutrophil elastase, myeloperoxidase, cathepsin G, proteinase 3, high mobility group protein B1, and LL37. Reportedly, NETosis can be induced by several microbes, and particulate matter including sterile stimuli, via distinct cellular mechanisms. Meanwhile, suicidal NETosis and vital NETosis are controversial. As we enter the second decade of research on NETosis, we have partly understood NETs as double-edged swords of innate immunity. In this review, we will discuss the mechanisms of NETosis, its antimicrobial action, and role in autoimmune diseases, as well as the relatively new field of NET-associated mitochondrial DNA.