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Anti-citrullinated protein antibodies contribute to platelet activation in rheumatoid arthritis.

Habets KL, Trouw LA, Levarht EW, Korporaal SJ, Habets PA, de Groot P, Huizinga TW, Toes RE - Arthritis Res. Ther. (2015)

Bottom Line: Furthermore, levels of P-selectin expression and sCD40L release correlated with high ACPA titres.Pre-incubation of platelets with blocking antibodies directed against low-affinity immunoglobulin G receptor (FcγRIIa) completely inhibited the ACPA-mediated activation.In addition, expression of P-selectin measured as number of platelets correlated with Disease Activity Score in 44 joints, C-reactive protein level, ACPA status and ACPA level.

View Article: PubMed Central - PubMed

Affiliation: Department of Rheumatology, Leiden University Medical Centre, C1-R, PO Box 9600, 2300, RC, Leiden, the Netherlands. k.l.l.habets@lumc.nl.

ABSTRACT

Introduction: Although the role of platelets in rheumatoid arthritis (RA) is relatively unexplored, recent studies point towards a contribution of platelets in arthritis. We set out to determine platelet phenotype in RA and studied whether this could be influenced by the presence of anti-citrullinated protein antibodies (ACPA).

Methods: Platelets from healthy controls were incubated in the presence of plasma of patients with RA or age- and sex-matched healthy controls and plasma from ACPA(neg) or ACPA(pos) patients or in the presence of plate-bound ACPA. Characteristics of platelets isolated from patients with RA were correlated to disease activity.

Results: Platelets isolated from healthy controls displayed markers of platelet activation in the presence of plasma derived from RA patients, as determined by P-selectin expression, formation of aggregates and secretion of soluble CD40 ligand (sCD40L). Furthermore, levels of P-selectin expression and sCD40L release correlated with high ACPA titres. In accordance with these findings, enhanced platelet activation was observed after incubation with ACPA(pos) plasma versus ACPA(neg) plasma. Pre-incubation of platelets with blocking antibodies directed against low-affinity immunoglobulin G receptor (FcγRIIa) completely inhibited the ACPA-mediated activation. In addition, expression of P-selectin measured as number of platelets correlated with Disease Activity Score in 44 joints, C-reactive protein level, ACPA status and ACPA level.

Conclusions: We show for the first time that ACPA can mediate an FcγRIIa-dependent activation of platelets. As ACPA can be detected several years before RA disease onset and activated platelets contribute to vascular permeability, these data implicate a possible role for ACPA-mediated activation of platelets in arthritis onset.

No MeSH data available.


Related in: MedlinePlus

Plasma-derived factors enhance platelet activity. Platelets were isolated from buffy coat and incubated in the presence of plasma obtained from patients with rheumatoid arthritis (RA) or age- and sex-matched healthy controls (cohort 1). Plasma from patients with RA induced higher platelet activation than did plasma from healthy donors, as indicated by (a) increased percentage and (b) mean fluorescence intensity (MFI) of P-selectin (CD62P) expression, (d) platelet aggregation and (f) soluble CD40 ligand (sCD40L). c Histogram overlay showing representative examples of CD62P expression. e Representative pictures of aggregate formation and CD62P expression of non-aggregated and aggregated platelets. f Values of sCD40L were corrected for amounts present in plasma. Levels of (g) P-selectin and (h) sCD40L production correlated with high levels of anti-citrullinated protein antibodies (ACPA; > 1000 AU/ml). Each symbol represents a plasma sample. FSC forward scatter, SSC side scatter
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Fig1: Plasma-derived factors enhance platelet activity. Platelets were isolated from buffy coat and incubated in the presence of plasma obtained from patients with rheumatoid arthritis (RA) or age- and sex-matched healthy controls (cohort 1). Plasma from patients with RA induced higher platelet activation than did plasma from healthy donors, as indicated by (a) increased percentage and (b) mean fluorescence intensity (MFI) of P-selectin (CD62P) expression, (d) platelet aggregation and (f) soluble CD40 ligand (sCD40L). c Histogram overlay showing representative examples of CD62P expression. e Representative pictures of aggregate formation and CD62P expression of non-aggregated and aggregated platelets. f Values of sCD40L were corrected for amounts present in plasma. Levels of (g) P-selectin and (h) sCD40L production correlated with high levels of anti-citrullinated protein antibodies (ACPA; > 1000 AU/ml). Each symbol represents a plasma sample. FSC forward scatter, SSC side scatter

Mentions: As described, patients with RA display a more activated platelet phenotype, but the underlying mechanism is not clear. To investigate if plasma-derived factors could have contributed to this observation, we incubated freshly isolated platelets from healthy volunteers with plasma obtained from patients with RA. To ensure moderate to high disease activity, only plasma of patients with a DAS44 > 2.4 were included. Plasma from age- and sex-matched healthy volunteers was used as a control (cohort 1). Increased expression of P-selectin (21.6±0.5 % vs 24.4±0.6 %; P<0.001) (Fig. 1a), increased P-selectin mean fluorescence intensity (MFI) (119.5±1.5 vs 130.5±2.0; P<0.0001) (Fig. 1b), more platelet aggregation (3.3±0.1 vs. 3.9±0.2; P<0.01) (Fig. 1d) and enhanced production of sCD40L (0.99±0.0.14 ng/ml vs 1.5±0.18 ng/ml; P<0.05) (Fig. 1f) were detected after incubation of platelets of healthy subjects in the presence of plasma from patients with RA. Notably, linear regression analysis indicated that platelet characteristics such as P-selectin expression, aggregate formation and the production of sCD40L induced by a given plasma sample predicted group in the plasma donor (control vs patients with RA) (Table 2).Fig. 1


Anti-citrullinated protein antibodies contribute to platelet activation in rheumatoid arthritis.

Habets KL, Trouw LA, Levarht EW, Korporaal SJ, Habets PA, de Groot P, Huizinga TW, Toes RE - Arthritis Res. Ther. (2015)

Plasma-derived factors enhance platelet activity. Platelets were isolated from buffy coat and incubated in the presence of plasma obtained from patients with rheumatoid arthritis (RA) or age- and sex-matched healthy controls (cohort 1). Plasma from patients with RA induced higher platelet activation than did plasma from healthy donors, as indicated by (a) increased percentage and (b) mean fluorescence intensity (MFI) of P-selectin (CD62P) expression, (d) platelet aggregation and (f) soluble CD40 ligand (sCD40L). c Histogram overlay showing representative examples of CD62P expression. e Representative pictures of aggregate formation and CD62P expression of non-aggregated and aggregated platelets. f Values of sCD40L were corrected for amounts present in plasma. Levels of (g) P-selectin and (h) sCD40L production correlated with high levels of anti-citrullinated protein antibodies (ACPA; > 1000 AU/ml). Each symbol represents a plasma sample. FSC forward scatter, SSC side scatter
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4548712&req=5

Fig1: Plasma-derived factors enhance platelet activity. Platelets were isolated from buffy coat and incubated in the presence of plasma obtained from patients with rheumatoid arthritis (RA) or age- and sex-matched healthy controls (cohort 1). Plasma from patients with RA induced higher platelet activation than did plasma from healthy donors, as indicated by (a) increased percentage and (b) mean fluorescence intensity (MFI) of P-selectin (CD62P) expression, (d) platelet aggregation and (f) soluble CD40 ligand (sCD40L). c Histogram overlay showing representative examples of CD62P expression. e Representative pictures of aggregate formation and CD62P expression of non-aggregated and aggregated platelets. f Values of sCD40L were corrected for amounts present in plasma. Levels of (g) P-selectin and (h) sCD40L production correlated with high levels of anti-citrullinated protein antibodies (ACPA; > 1000 AU/ml). Each symbol represents a plasma sample. FSC forward scatter, SSC side scatter
Mentions: As described, patients with RA display a more activated platelet phenotype, but the underlying mechanism is not clear. To investigate if plasma-derived factors could have contributed to this observation, we incubated freshly isolated platelets from healthy volunteers with plasma obtained from patients with RA. To ensure moderate to high disease activity, only plasma of patients with a DAS44 > 2.4 were included. Plasma from age- and sex-matched healthy volunteers was used as a control (cohort 1). Increased expression of P-selectin (21.6±0.5 % vs 24.4±0.6 %; P<0.001) (Fig. 1a), increased P-selectin mean fluorescence intensity (MFI) (119.5±1.5 vs 130.5±2.0; P<0.0001) (Fig. 1b), more platelet aggregation (3.3±0.1 vs. 3.9±0.2; P<0.01) (Fig. 1d) and enhanced production of sCD40L (0.99±0.0.14 ng/ml vs 1.5±0.18 ng/ml; P<0.05) (Fig. 1f) were detected after incubation of platelets of healthy subjects in the presence of plasma from patients with RA. Notably, linear regression analysis indicated that platelet characteristics such as P-selectin expression, aggregate formation and the production of sCD40L induced by a given plasma sample predicted group in the plasma donor (control vs patients with RA) (Table 2).Fig. 1

Bottom Line: Furthermore, levels of P-selectin expression and sCD40L release correlated with high ACPA titres.Pre-incubation of platelets with blocking antibodies directed against low-affinity immunoglobulin G receptor (FcγRIIa) completely inhibited the ACPA-mediated activation.In addition, expression of P-selectin measured as number of platelets correlated with Disease Activity Score in 44 joints, C-reactive protein level, ACPA status and ACPA level.

View Article: PubMed Central - PubMed

Affiliation: Department of Rheumatology, Leiden University Medical Centre, C1-R, PO Box 9600, 2300, RC, Leiden, the Netherlands. k.l.l.habets@lumc.nl.

ABSTRACT

Introduction: Although the role of platelets in rheumatoid arthritis (RA) is relatively unexplored, recent studies point towards a contribution of platelets in arthritis. We set out to determine platelet phenotype in RA and studied whether this could be influenced by the presence of anti-citrullinated protein antibodies (ACPA).

Methods: Platelets from healthy controls were incubated in the presence of plasma of patients with RA or age- and sex-matched healthy controls and plasma from ACPA(neg) or ACPA(pos) patients or in the presence of plate-bound ACPA. Characteristics of platelets isolated from patients with RA were correlated to disease activity.

Results: Platelets isolated from healthy controls displayed markers of platelet activation in the presence of plasma derived from RA patients, as determined by P-selectin expression, formation of aggregates and secretion of soluble CD40 ligand (sCD40L). Furthermore, levels of P-selectin expression and sCD40L release correlated with high ACPA titres. In accordance with these findings, enhanced platelet activation was observed after incubation with ACPA(pos) plasma versus ACPA(neg) plasma. Pre-incubation of platelets with blocking antibodies directed against low-affinity immunoglobulin G receptor (FcγRIIa) completely inhibited the ACPA-mediated activation. In addition, expression of P-selectin measured as number of platelets correlated with Disease Activity Score in 44 joints, C-reactive protein level, ACPA status and ACPA level.

Conclusions: We show for the first time that ACPA can mediate an FcγRIIa-dependent activation of platelets. As ACPA can be detected several years before RA disease onset and activated platelets contribute to vascular permeability, these data implicate a possible role for ACPA-mediated activation of platelets in arthritis onset.

No MeSH data available.


Related in: MedlinePlus