Decreased Activity of Plasma ADAMTS13 Parallels Enhanced Endotoxemia in Patients with Severe Acute Pancreatitis: Relationship to Multiorgan Failure

Abstract

Background: Severe acute pancreatitis (SAP) frequently progresses to pancreatitis-associated multiorgan failure (MOF) with high mortality. Decreased plasma ADAMTS13 activity (ADAMTS13:AC) results in the accumulation of unusually large von Willebrand factor multimers (UL-VWFM) and the formation of platelet thrombi, ultimately leading to MOF. We demonstrated that the imbalance between decreased ADAMTS13:AC and increased UL-VWFM could contribute to SAP pathogenesis through enhanced thrombogenesis, and serve as an early prognostic indicator for SAP patients (Scand J Gastroenterol , 2008, 26:1). Endotoxin has been considered to be the principle activator of the systemic inflammatory response syndrome, which predisposes patients for MOF and/or pancreatic necrosis, ultimately leading to SAP. We investigated the relationship of endotoxin to ADAMTS13:AC and its related parameters, and tried to explore their potential role on the development of MOF in patients with SAP.Methods: We sequentially determined plasma endotoxin concentration, ADAMTS13:AC and its related parameters in 13 SAP patients (APACHE-II score mean 6.6 ± 2.7), who were admitted into intensive care unit of our hospital between 2004 and 2006. Eleven patients were survivors and two were non-survivors whose APACHE II scores were 10 and 12 died of MOF, respectively. The degree of MOF was evaluated according to the SOFA score. Endotoxin concentration was determined by a chromogenic substrate assay (Toxicolor LS –M Set, Seikagaku Kogyo Co.) with kinetic analysis after pretreatment with detergent, Triton X-100, and heating at 70 °C for 10 min. Plasma ADAMTS13:AC was determined by a sensitive chromogenic ELISA (ADAMTS13-act-ELISA: Kainos Inc.). Plasma UL-VWFM was analyzed by a vertical SDS-1.0% agarose gel electrophoresis. Plasma VWF antigen (VWF:AG), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor -α (TNF-α) were measured by ELISA.Results: In normal healthy controls (n=20), plasma endotoxin concentration was 7.9±1.7 pg/ml (mean ± SD). The concentration in the SAP patients significantly increased at day 1 (means 65 pg/ml, p<0.001) and at day 2 (88 pg/ml, p<0.001) as compared to healthy controls. The values, thereafter, gradually decreased in 8 survivors (55 pg/ml at day 5, 53 pg/ml at day 7, 27 pg/ml at day 14), while in remaining 3 survivors needing necrosectomy, the concentration further increased (98 pg/ml at day 5, 178 pg/ml at day 7), and decreased to 20 pg/ml at day 14 at the recovery phase. In two non-survivors, the endotoxin levels increased from 37 pg/ml at day 1 to 462 pg/ml at day 2 in one needing necrosectomy, and showed 51 pg/ml at day 1 in another at the age of 91. Within 1 or 2 days after admission, the ADAMTS13:AC was lower in SAP patients (mean 29%, p<0.001) than in healthy controls (99%), and gradually recovered in the 11 survivors but further decreased in the 2 non-survivors. On admission, VWF:Ag was higher (402%, p<0.001) in SAP patients than controls (100%). VWF:Ag gradually decreased in the survivors, except in the 3 survivors needing a necrosectomy, but remained high in the non-survivors. UL-VWFM positive patients showed lower ADAMTS13:AC (25% vs. 42%, p<0.05) and higher VWF:Ag ( 481% vs. 332%, p<0.05), resulting in higher ratio of VWF:Ag to ADAMTS13:AC (25.2 vs. 9.1, p<0.02), as compared to UL-VWFM negative ones. Patients with higher endotoxin concentration more than 50 pg/ml showed lower ADAMTS13:AC than those without (22% vs. 43%, p<0.05). Plasma endotoxin concentration positively correlated with the ratio of VWF:Ag to ADAMTS13:AC (r=0.732, p<0.005). The SOFA score correlated positively with plasma endotoxin concentration (r=0.604, p<0.03), IL-8 (r=0.843, p<0.001), and the ratio of VWF:Ag to ADAMTS13:AC (r=0.700, p<0.01), and inversely with the ADAMTS13:AC (r= − 0.601, p<0.03).Conclusion. The imbalance between decreased ADAMTS13:AC and increased UL-VWFM is closely related to enhanced endotoxemia, which may contribute to the development of SAP and subsequent MOF through enhanced thrombogenesis.