Level of platelet microparticles in acute pancreatitis and their role in the formation of neutrophil extracellular traps

Objective To investigate the change in the level of platelet microparticles( PMPs) in acute pancreatitis( AP) and the ability of PMPs to promote the formation of neutrophil extracellular traps( NETs). Methods Blood samples were collected from 55 patients with AP who were admitted to The First Affiliated Hospital of Anhui Medical University from September 2018 to August 2019,and these patients were divided into mild AP( MAP) group with 26 patients,moderate-severe AP( MSAP) group with 17 patients,and severe AP( SAP) group with 12 patients. A total of 15 healthy individuals who underwent physical examination were enrolled as control group. Platelet-poor plasma( PPP)was separated by differential centrifugation and flow cytometry was used to measure the level of PMPs. Neutrophils were collected from the control group and were co-cultured with the PMPs from AP patients. ELISA was used to measure the levels of myeloperoxidase( MPO),neutrophil elastase( NE),and histone H3 in culture solution,and a laser scanning confocal microscope was used to observe the distribution of NETs. The t-test was used for comparison of continuous data between two groups,and a one-way analysis of variance or the Kruskal-Wallis H test was used for comparison between multiple groups; the chi-square test was used for comparison of categorical data between groups; a Pearson correlation analysis was also performed. Results Compared with the control group,the MAP,MSAP,and SAP groups had a significant increase in the level of PMPs [179. 50( 145. 00-308. 750)/μl,1117. 50( 483. 00-2488. 25)/μl,and 1848. 00( 1216. 50-2562. 00)/μl vs 172. 00( 148. 25-204. 25)/μl,H = 4. 348、23. 186、19. 293,all P < 0. 05],and compared with the MAP and MSAP groups,the SAP group had a significant increase in the level of PMPs( H = 29. 068、4. 709,both P < 0. 05). The level of PMPs in AP patients was correlated with APACHEII,BISAP,and Ranson score( r = 0. 636,0. 508,and 0. 430,all P < 0. 001). Compared with the control group,the AP group had significantly increases in the levels of MPO[( 374. 68 ± 92. 01) ng/ml vs( 105. 27 ± 33. 82) ng/ml,t = 9. 105,P < 0. 001],NE[( 267. 45 ± 68. 46) ng/ml vs( 82. 71 ± 19. 22) ng/ml,t = 9. 921,P < 0. 001],and histone H3[( 16. 34 ±4. 02) ng/ml vs( 4. 53 ± 1. 48) ng/ml,t = 7. 524,P < 0. 001],and the formation of NETs was increased under the laser scanning confocal microscope. Conclusion The level of PMPs is significantly increased in AP,which is associated with disease activity. PMPs may promote the formation of NETs and aggravate the progression of AP.