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Letter

Contribution of activated platelets to plasma IL-27 levels

Hind Hamzeh-Cognasse1, Pauline Damien1, Kim Anh Nguyen1, Fabrice Zeni12, Bruno Pozzetto13, Fabrice Cognasse14 and Olivier Garraud14*

Author Affiliations

1 Université de Lyon, F-42023, GIMAP, EA3064, Saint Etienne, France

2 Service de reanimation medicale, CHU de Saint-Etienne 42270, France

3 Laboratoire de bacteriologie-virologie, CHU de Saint-Etienne 42270, France

4 EFS Auvergne-Loire and GIMAP-EA 3064, Université de Saint-Etienne, Faculté de Médecine, 15 rue Ambroise Paré, 42023 Saint-Etienne cedex 2, France

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Critical Care 2013, 17:411  doi:10.1186/cc11925


See related research by Wong et al., http://ccforum.com/content/16/5/R213


The electronic version of this article is the complete one and can be found online at: http://ccforum.com/content/17/1/411


Published:5 February 2013

© 2013 BioMed Central Ltd

Letter

In a recent issue of Critical Care, Wong and colleagues [1] demonstrated that the serum concentration of IL-27 in critically ill children was a predictor of infection. Our study aims at determining whether platelet activation contributes to the elevated plasma IL-27 concentration. Here we demonstrate that activation of platelets with thrombin receptor activating peptide (TRAP) significantly increased IL-27 levels in supernatants (Figure 1a). Moreover, B cells incubated in vitro with supernatants from activated platelets upregulated membrane expression of CD86, which was restored to baseline when B cells were pre-incubated with a gp130 blocking antibody (Figure 1b). Our data strongly suggest that platelet activation contributes, along with classical sources [2], to elevated plasma levels of IL-27. Recent advances place platelets as an important link between innate and adaptive immunity [3]. Indeed, platelets modulate their inflammatory response after sensing the presence of an infectious agent [4]. Therefore, platelet activation could contribute to increased plasma concentrations of IL-27 along with cytokines such as soluble CD40L [5], and thus may contribute towards immune dysregulation in patients with sepsis.

thumbnailFigure 1. Activated platelets release abundant and functional IL-27. (A) Platelets from apheresis platelet concentrates (n = 11) were stimulated with TRAP-SFFLRN peptide (50 μg/ml, 30 minutes; Sigma-Aldrich, Saint-Quentin Fallavier, France); negative controls were not stimulated. IL-27 concentration in platelet supernatants was determined using a commercial enzyme-linked immunosorbent assay kit (RnD Systems Europe, Lille, France). Thrombin receptor activating peptide (TRAP) stimulation significantly increased IL-27 release from 18.42 ± 2.28 ng/ml to 47.17 ± 2.99 ng/ml (***P < 0.0005, t-test). (B) Then, the influence of IL-27-rich platelet supernatants on the expression of the activation marker CD86 was assessed in vitro on five independent highly purified blood B lymphocyte sets by means of flow cytometry, in duplicate for each condition. As a control, each set of B cells was incubated in minimal medium for 48 h with recombinant IL-27 (10 ng/ml; RnD Systems). We found that, in contrast to supernatants of non-activated platelets, supernatants of activated platelets provoke a significant increase in CD86 expression on B cells from 21 to 47% (*P < 0.05, t-test). CD86 expression was restored to baseline when B cells were pre-incubated with an antibody blocking the gp130 subunit of the IL-27 receptor (0.5 μg/ml; clone 28126, RnD Systems; #P < 0.05, t-test). Results are presented as mean values ± standard deviations.

Abbreviations

IL: interleukin; TRAP: thrombin receptor activating peptide.

Competing interests

The authors declare that they have no competing interests.

Acknowledgements

The authors thank MA Eyraud and CA Arthaud for technical assistance. This work was supported by the EFS (grant APR2010-No10) the ANR (grant ANR-12- JSV1), the ART, and the 'Les Amis de Rémi' Association; France. In accordance with French regulations, platelets were obtained from regular blood donors who signed a form indicating that they do not preclude the use of their sample for medical research.

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