Reply to: “Circulating platelet derived microparticles are not increased in patients with cirrhosis”
Authors: Elliot B. Tapper, Simon Robson, Raza Malik
Journal: Journal of Hepatology (2013)

Circulating platelet derived microparticles are not increased in patients with cirrhosisJournal of HepatologyVol. 59Issue 4PreviewIn their Snapshot, Tapper, Robson, and Malik suggest that circulating platelet-derived microparticles are increased in cirrhosis as a function of systemic inflammation [1]. Ogasawara and colleagues observed higher levels of circulating platelet microparticles in 22 patients with cirrhosis as compared to 17 healthy controls [2]. However, the results of two other independent studies assessing circulating platelet microparticle levels in patients with cirrhosis do not concur. Sayed and colleagues included 60 patients with hepatitis C related cirrhosis and 20 healthy controls [3]. Full-Text PDF Open AccessCoagulopathy in cirrhosis – The role of the platelet in hemostasisJournal of HepatologyVol. 59Issue 4PreviewCirrhotic patients are at increased risk of bleeding, particularly gastrointestinal bleeding, as a consequence of portal hypertension and/or coagulopathy attributed to liver synthetic dysfunction. Paradoxically, they are also at risk of thrombosis, predominantly in the splanchnic circulation, especially when platelet counts are increased by transfusion or drug therapy [1,2]. A major problem in clinical practice is the inadequacy of coagulation tests, which do not predict bleeding or thrombotic events, but may result in the inappropriate administration of therapies (e.g., plasma transfusions prior to procedures). Full-Text PDF Open Access We thank Dr. Rautou et al. for their interest in our Snapshot review (in which we sought to summarize the important role that platelets play in mediating coagulation and thrombosis in patients with cirrhosis) [[1]Tapper E.B. Robson S.C. Malik R. Coagulopathy in cirrhosis – the role of the platelet in hemostasis.J Hepatol. 2013; 59: 889-890Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar]. We proposed that microparticles could have important effects on coagulation and thrombosis in these clinical settings. We mentioned the possibility of circulating cell-derived, and by inference (given the current state of the field), platelet microparticles as possible mediators of inflammation. Rautou and colleagues correctly point out that they and other groups have recently published data in this area [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. In acute and chronic liver diseases, circulating microparticle levels have consistently been shown to be increased, albeit previous studies have shown variable levels of platelet-derived microparticles in these settings [3Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar, 4Sayed D. Amin N.F. Galal G.M. Monocyte-platelet aggregates and platelet microparticles in patients with post-hepatitic liver cirrhosis.Thromb Res. 2010; 125: e228-e233Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar, 5Schmelzle M. Splith K. Andersen L.W. Kornek M. Schuppan D. Jones-Bamman C. et al.Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury.Transplantation. 2013; 95: 63-69Crossref PubMed Scopus (33) Google Scholar, 6Kornek M. Lynch M. Mehta S.H. Lai M. Exley M. Afdhal N.H. et al.Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis.Gastroenterology. 2012; 143: 448-458Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar, 7Stravitz R.T. Bowling R. Bradford R.L. Key N.S. Glover S. Thacker L.R. et al.Role of procoagulant microparticles in mediating complications and outcome of acute liver injury/acute liver failure.Hepatology. 2013; ([Epub ahead of print])https://doi.org/10.1002/hep.26307Crossref Scopus (82) Google Scholar]. Importantly, Rautou et al. also found that “the severity of cirrhosis and systemic inflammation were major determinants of the levels of leuko-endothelial and hepatocyte microparticles” [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. Specifically, after correcting for the circulating concentrations of platelets, the levels of platelet-derived microparticles in this study are lower in cirrhotic patients when compared to controls [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. Other investigators have suggested increased levels of platelet microparticles in cirrhosis [[3]Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar] or that no differences are associated with increasing levels of hepatic fibrosis [[6]Kornek M. Lynch M. Mehta S.H. Lai M. Exley M. Afdhal N.H. et al.Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis.Gastroenterology. 2012; 143: 448-458Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar].The origins of circulating microparticles, whether platelet-derived or not, remain a point of contention. In truth, this is a field in evolution where critical elements of methodology are yet to be determined. For example, Rautou et al. and other groups have measured static microparticle levels. It is not clear if such static values are pathophysiologically relevant, in relation to a given stimulus, or whether the rapidity of changes in concentration levels and fluxes over time are more important [[5]Schmelzle M. Splith K. Andersen L.W. Kornek M. Schuppan D. Jones-Bamman C. et al.Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury.Transplantation. 2013; 95: 63-69Crossref PubMed Scopus (33) Google Scholar]. Nor is it clear whether determination of CD41 labeling is sufficient to describe platelet versus megakaryocyte-derived microparticles – in either health or disease states [8Christersson C. Johnell M. Siegbahn A. Evaluation of microparticles in whole blood by multicolour flow cytometry assay.Scand J Clin Lab Invest. 2013; 73: 229-239Crossref PubMed Scopus (32) Google Scholar, 9Strasser E.F. Happ S. Weiss D.R. Pfeiffer A. Zimmermann R. Eckstein R. Microparticle detection in platelet products by three different methods.Transfusion. 2013; 53: 156-166Crossref PubMed Scopus (27) Google Scholar, 10Italiano Jr., J.E. Mairuhu A.T. Flaumenhaft R. Clinical relevance of microparticles from platelets and megakaryocytes.Curr Opin Hematol. 2010; 17: 578-584Crossref PubMed Scopus (231) Google Scholar]. While Rautou et al. utilize CD41 as a marker of platelet microparticles, the article that we had cited utilized the related marker CD61 to measure platelet microparticles and infer that these may vary with inflammatory insults as during and after an alcoholic binge [[3]Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar].Finally, Rautou et al. suggest tissue factor expressing microparticles may be more relevant as prothrombotic mediators in liver disease and not platelet microparticles per se. Tissue factor expression, typically thought to be distinct from platelet-derived microparticles, can be readily found co-expressed with CD41 in plasma microparticles using whole blood analyses and modified techniques [[8]Christersson C. Johnell M. Siegbahn A. Evaluation of microparticles in whole blood by multicolour flow cytometry assay.Scand J Clin Lab Invest. 2013; 73: 229-239Crossref PubMed Scopus (32) Google Scholar]. Clearly, microparticles can co-express a variety of surface proteins (e.g., CD39), likely with unique biological properties depending on both source and target interaction [[11]Banz Y. Beldi G. Wu Y. Atkinson B. Usheva A. Robson S.C. CD39 is incorporated into plasma microparticles where it maintains functional properties and impacts endothelial activation.Br J Haematol. 2008; 142: 627-637Crossref PubMed Scopus (49) Google Scholar]. Further, one might speculate that microparticles from platelets and other cellular sources could function as transport and delivery systems for bioactive molecules in vivo, participating not only in hemostasis and thrombosis but also in inflammation, angiogenesis, tissue remodeling, and cellular transformation [[11]Banz Y. Beldi G. Wu Y. Atkinson B. Usheva A. Robson S.C. CD39 is incorporated into plasma microparticles where it maintains functional properties and impacts endothelial activation.Br J Haematol. 2008; 142: 627-637Crossref PubMed Scopus (49) Google Scholar].As this field matures and more data is available, the controversies that uncertainty brings will likely settle. Future studies are needed to understand the respective roles of static/dynamic changes in concentrations, to standardize methodology for the quantification process and to delineate not only the absolute levels but also, importantly, any qualitative differences in microparticle populations.Conflict of interestThe authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. We thank Dr. Rautou et al. for their interest in our Snapshot review (in which we sought to summarize the important role that platelets play in mediating coagulation and thrombosis in patients with cirrhosis) [[1]Tapper E.B. Robson S.C. Malik R. Coagulopathy in cirrhosis – the role of the platelet in hemostasis.J Hepatol. 2013; 59: 889-890Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar]. We proposed that microparticles could have important effects on coagulation and thrombosis in these clinical settings. We mentioned the possibility of circulating cell-derived, and by inference (given the current state of the field), platelet microparticles as possible mediators of inflammation. Rautou and colleagues correctly point out that they and other groups have recently published data in this area [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. In acute and chronic liver diseases, circulating microparticle levels have consistently been shown to be increased, albeit previous studies have shown variable levels of platelet-derived microparticles in these settings [3Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar, 4Sayed D. Amin N.F. Galal G.M. Monocyte-platelet aggregates and platelet microparticles in patients with post-hepatitic liver cirrhosis.Thromb Res. 2010; 125: e228-e233Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar, 5Schmelzle M. Splith K. Andersen L.W. Kornek M. Schuppan D. Jones-Bamman C. et al.Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury.Transplantation. 2013; 95: 63-69Crossref PubMed Scopus (33) Google Scholar, 6Kornek M. Lynch M. Mehta S.H. Lai M. Exley M. Afdhal N.H. et al.Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis.Gastroenterology. 2012; 143: 448-458Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar, 7Stravitz R.T. Bowling R. Bradford R.L. Key N.S. Glover S. Thacker L.R. et al.Role of procoagulant microparticles in mediating complications and outcome of acute liver injury/acute liver failure.Hepatology. 2013; ([Epub ahead of print])https://doi.org/10.1002/hep.26307Crossref Scopus (82) Google Scholar]. Importantly, Rautou et al. also found that “the severity of cirrhosis and systemic inflammation were major determinants of the levels of leuko-endothelial and hepatocyte microparticles” [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. Specifically, after correcting for the circulating concentrations of platelets, the levels of platelet-derived microparticles in this study are lower in cirrhotic patients when compared to controls [[2]Rautou P.E. Bresson J. Sainte-Marie Y. Vion A.C. Paradis V. Renard J.M. et al.Abnormal plasma microparticles impair vasoconstrictor responses in patients with cirrhosis.Gastroenterology. 2012; 143: 166-176Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar]. Other investigators have suggested increased levels of platelet microparticles in cirrhosis [[3]Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar] or that no differences are associated with increasing levels of hepatic fibrosis [[6]Kornek M. Lynch M. Mehta S.H. Lai M. Exley M. Afdhal N.H. et al.Circulating microparticles as disease-specific biomarkers of severity of inflammation in patients with hepatitis C or nonalcoholic steatohepatitis.Gastroenterology. 2012; 143: 448-458Abstract Full Text Full Text PDF PubMed Scopus (138) Google Scholar]. The origins of circulating microparticles, whether platelet-derived or not, remain a point of contention. In truth, this is a field in evolution where critical elements of methodology are yet to be determined. For example, Rautou et al. and other groups have measured static microparticle levels. It is not clear if such static values are pathophysiologically relevant, in relation to a given stimulus, or whether the rapidity of changes in concentration levels and fluxes over time are more important [[5]Schmelzle M. Splith K. Andersen L.W. Kornek M. Schuppan D. Jones-Bamman C. et al.Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury.Transplantation. 2013; 95: 63-69Crossref PubMed Scopus (33) Google Scholar]. Nor is it clear whether determination of CD41 labeling is sufficient to describe platelet versus megakaryocyte-derived microparticles – in either health or disease states [8Christersson C. Johnell M. Siegbahn A. Evaluation of microparticles in whole blood by multicolour flow cytometry assay.Scand J Clin Lab Invest. 2013; 73: 229-239Crossref PubMed Scopus (32) Google Scholar, 9Strasser E.F. Happ S. Weiss D.R. Pfeiffer A. Zimmermann R. Eckstein R. Microparticle detection in platelet products by three different methods.Transfusion. 2013; 53: 156-166Crossref PubMed Scopus (27) Google Scholar, 10Italiano Jr., J.E. Mairuhu A.T. Flaumenhaft R. Clinical relevance of microparticles from platelets and megakaryocytes.Curr Opin Hematol. 2010; 17: 578-584Crossref PubMed Scopus (231) Google Scholar]. While Rautou et al. utilize CD41 as a marker of platelet microparticles, the article that we had cited utilized the related marker CD61 to measure platelet microparticles and infer that these may vary with inflammatory insults as during and after an alcoholic binge [[3]Ogasawara F. Fusegawa H. Haruki Y. Shiraishi K. Watanabe N. Matsuzaki S. Platelet activation in patients with alcoholic liver disease.Tokai J Exp Clin Med. 2005; 30: 41-48PubMed Google Scholar]. Finally, Rautou et al. suggest tissue factor expressing microparticles may be more relevant as prothrombotic mediators in liver disease and not platelet microparticles per se. Tissue factor expression, typically thought to be distinct from platelet-derived microparticles, can be readily found co-expressed with CD41 in plasma microparticles using whole blood analyses and modified techniques [[8]Christersson C. Johnell M. Siegbahn A. Evaluation of microparticles in whole blood by multicolour flow cytometry assay.Scand J Clin Lab Invest. 2013; 73: 229-239Crossref PubMed Scopus (32) Google Scholar]. Clearly, microparticles can co-express a variety of surface proteins (e.g., CD39), likely with unique biological properties depending on both source and target interaction [[11]Banz Y. Beldi G. Wu Y. Atkinson B. Usheva A. Robson S.C. CD39 is incorporated into plasma microparticles where it maintains functional properties and impacts endothelial activation.Br J Haematol. 2008; 142: 627-637Crossref PubMed Scopus (49) Google Scholar]. Further, one might speculate that microparticles from platelets and other cellular sources could function as transport and delivery systems for bioactive molecules in vivo, participating not only in hemostasis and thrombosis but also in inflammation, angiogenesis, tissue remodeling, and cellular transformation [[11]Banz Y. Beldi G. Wu Y. Atkinson B. Usheva A. Robson S.C. CD39 is incorporated into plasma microparticles where it maintains functional properties and impacts endothelial activation.Br J Haematol. 2008; 142: 627-637Crossref PubMed Scopus (49) Google Scholar]. As this field matures and more data is available, the controversies that uncertainty brings will likely settle. Future studies are needed to understand the respective roles of static/dynamic changes in concentrations, to standardize methodology for the quantification process and to delineate not only the absolute levels but also, importantly, any qualitative differences in microparticle populations. Conflict of interestThe authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.