| Ulcerative colitis(UC)is a major type of inflammatory bowel disease(IBD),is a chronic inflammatory condition characterized by local and systemic inflammation predominantly affecting the gastrointestinal tract.Patients with ulcerative colitis are at increased risk of thromboembolic complications which may affect patients’ survival rate and mortality.Historically,in 1936,Bargen and Barker first reported arterial and venous thrombotic complications in UC patients.In a large Mayo Clinic survey,Talbot et al found that 1.3% of their IBD patients manifested thromboembolic complications,while other early studies reported an even higher incidence,up to 7%.Moreover,an observation came from autopsy studies which found a much higher incidence of venous thromboembolic complications,up to 39%,in UC patients,implying that most of the thromboembolic episodes were either not clinically overt or were overlooked.The thromboembolic complications were the third leading cause of death(10%)in those patients.The hypercoagulable state is associated with inflammation and appearance,with the inflammation control and mitigation.Thrombus can cause intestinal mucosal ischemia and necrosis,severe ulcer formation,thereby increasing the UC patients with colonic and rectal mucosal lesions.Therefore,the complication of thromboembolism has become the main reason for the deterioration of UC disease,seriously affect the quality of life of UC patients,endanger their lives.UC is a complex group of diseases involving alterations in mucosal immunity and gastrointestinal physiology during both initiation and progressive phases of the disease.A recent study showed that the pathological abnormalities of UC not only may reflect dysfunction within antigen-presenting cells(e.g.dendritic cells)or excess activation of CD4+ T-cells(resembling T-cell disturbances),but also involve non-immune cells,such as microvascular endothelial cells,which regulate recruitment of inflammatory cells,tissue damage(e.g.vasogenic edema),and production of inflammatory mediators.Inflammation and coagulation constantly influence each other and are constantly in balance.Emerging evidence supports this statement in UC mainly for micro-thrombosis and microcirculation.Vascular endothelium has been shown to be the interface of them interaction,whereas protein C(PC)pathway is an important mediator of vascular endothelial function.The protein C pathway is the system of natural coagulation inhibitors,which involed two vitamin K-dependent plasma proteins,the zymogen PC and the cofactor protein S(PS),and membrane receptors,the thrombomodulin(TM)and the endothelial protein C receptor(EPCR).The anticoagulation pathway mainly through the inactivation of coagulation factorsⅤand Ⅷ,limiting factorⅩa and platelet binding and enhance fibrin dissolution,directly affect the coagulation-anticoagulant mechanism of dynamic balance.The increased risk of thromboembolic complications in UC is largely dependent on the biological and biochemical effects exerted by the activation of the inflammatory pathways(e.g.cells and cytokines)in the haemostatic system.Tumor necrosis factor(TNF-α)is mainly produced by macrophages,T cells and NK cells,and associated with local inflammation,has confirmed that it has an important core position in the inflammation-induced coagulation activation process.In the case of TNF-α stimulation,a variety of coagulation parameters were detected and the results showed that the coagulation pathway was activated.Interleukin-6(IL-6)can also induce the activation of coagulation system,and the application of anti-IL-6 can prevent coagulation abnormalities caused by systemic infection.TNF-α and IL-6 have been shown to induce the expression of tissue factor(TF)on the cell surface of leucocytes.It is speculated that cytokines promote the formation of hypercoagulable state by TF expression.Studies have shown that TNF-α,IL-6 and other inflammatory cytokines may stimulate the colon microvascular endothelial cells to change the PC pathway.Objective: This article aims to explore the formation mechanism of hypercoagulability in patients with ulcerative colitis.Whether the activation of inflammatory factors in the pathogenesis of UC will lead to the inhibition of PC pathway,and whether the inhibition of PC pathway is related to the severity of UC.Methods:1 30 UC patients were collected as experimental subjects.Divide the subjects into three groups according to modified Mayo disease activity index: mild,moderate and sever.Mild group contains 10 cases,moderate group contains 8 cases,sever group contains 12 cases.Collect 11 cases of patients with colonic polyps as control group.2 The levels of plasma TNF-α and IL-6 were measured by ELISA,and the activities of PC and PS were measured by chromogenic substrate method.Collect 2 pieces of colonic mucosal at rectum-sigmoid junction under colonoscope.Observe the histopathology of colonic mucosa with HE staining.Detect the expression of TM and EPCR protein by immunohistochemistry method.Use the SPSS21.0 to analyze the experimental data,P<0.05 was statistically significant.Results:1 Plasma TNF-α,IL-6 levelsELISA results showed that compared with the control group,UC group of patients with plasma TNF-α,IL-6 levels were significantly increased.The statistical results of TNF-α level are severe group(373.695±23.651)pg/mL > moderate group(228.147±13.340)pg/mL > mild group(112.209±10.182)pg/mL >control group(33.179±9.811)pg/mL,comparison of any two group show that P< 0.05,the differences are statistically significant.The statistical results of IL-6 level are severe group(325.801±17.011)pg/mL > moderate group(214.022 ± 20.274)pg/mL > mild group(111.698 ± 12.498)pg/mL >control group(35.499±8.275)pg/mL,comparison of any two group show that P< 0.05,the differences are statistically significant.2 Plasma PC,PS activityThe results showed that the levels of plasma PC and PS in UC group were significantly lower than those in control group.The statistical results of PC activity are control group(110.55±15.845)%> mild group(66.20±7.510)%> moderate group(52.25±6.628)%> severe group(36.42±4.772)%,comparison of any two group show that P<0.05,the differences are statistically significant.The statistical results of PS activity are control group(111.82±15.760)%> mild group(65.70±9.117)%> moderate group(50.75±5.701)%> severe group(34.58±5.368)%,comparison of any two group show that P<0.05,the differences are statistically significant.3 Correlation analysis between plasma PC activity and inflammation degreeThe plasma TNF-α level was used as the independent variable,and the plasma PC activity was used as the dependent variable.The linear correlation analysis shows that the plasma PC activity in UC is of negative correlation with TNF-α levels,and the correlation coefficient is-0.934(P<0.05).4 HE stainingThe nucleus is purple blue,cytoplasm,collagen fibers and basement membrane were pink.The structure of colonic mucosal epithelial is integrity in control groupand glandular cells arranged in neat rows,contained numbers of goblet cells,a small amount of inflammatory cells infiltration in the lamina propria.UC groups show varying degrees of tissue mucosal injury,submucosal hyperemia and edema,crypt structural disorder and destruction,crypts,crypt epithelium massive neutrophil infiltration,goblet cells decreased,Paneth cell metaplasia.A large number of inflammatory cells immersed in the lamina propria in UC groups,such as neutrophils,eosinophils,infiltration of monocytes,lymphocytes,plasma cells and other cells,severe mucosal epithelial shedding.5 The expression of TM and EPCR in colonic mucosaImmunohistochemistry shows that TM and EPCR are dark brown in the colon mucosa in control group,mainly located in the mucosal and submucosal microvascular endothelial cells,but are brown in UC groups and the expression are lower than that in control group.Statistical analysis the optical density(OD)of TM are severe group(0.0834±0.0178)>moderate group(0.1466±0.0067)>mild group(0.2121±0.0160)>control group(0.3246±0.0145),comparison of any two group show that P<0.05,the differences are statistically significant.Statistical analysis the OD of EPCR are severe group(0.0888±0.0111)>moderate group(0.1438±0.0069)>mild group(0.1838±0.0119)>control group(0.3615±0.0190),comparison of any two group show that P<0.05,the differences are statistically significant.Conclusion:1 The levels of plasma TNF-α and IL-6 in patients with UC were significantly increased,while the plasma PC and PS activities were decreased and the expression of TM and EPCR protein in colonic tissue decreased,suggesting that PC system activity was inhibited.2 Correlation analysis showed that plasma PC activity in UC patients was negatively correlated with colitis severity.PC pathway inhibition plays a role in UC blood hypercoagulable state,and its activity level is associated with the severity of UC. |
