Chang Of CD47 Expression On Monocyte After Burn And Its Correlation With Inflammation

1. IntroductionBurn is a kind of inflammatory disease after injury, and it is considered as a clasic pathological model of systemic inflammation without infection. The most threaten of death to severely burned patients is multiple organ disfunction sydrome(MODS), of which the etiopathogenisis is the lost of control of systemic inflammation, that is systemic inflammatory response syndrome(SIRS). SIRS is a very common complication with a high incidence in patients with large burned area. Dysfunctiong of immune cells is the primary reason for systemic infection, MODS and even death after burned. So it is seriously important to prevent SIRS in the treatment of severe burns. In recent years, some studies focusing on mechanism of inflammation after burns have confirm the existence of inflammatory matters in plasma. The expression of many cytokines in plasma will change greatly after burns, and the balance between proinflammatory factors and anti-inflammatory factors plays an important role in inflammatory reaction and immune function. However, the present reports about changes of cytokine expression differ greatly. Monocytes function will also change a lot after burn/trauma, which is related with inflammatory response and immune function. Monocyte/Macrophage may present different phenotype and function differently according to different cytokine environment and inflammatory courses. Compensatory anti-inflammatory response syndrome (CARS) is induced by SIRS with prevalent anti-inflammatory factors. CARS is charactered by dysfunction of monocyte, which may be involved in organic failure. As a kind of thrombospondin 1 (TSP-1) receptor, CD47 expression on monocyte may changes a lot during inflammation and may be related to immune supression. However, there is few study about this and the clinic significance of CD47 in burnd patients.2. Objectives(1) To elucidate changes of cytokines in different burned patients and the correlation with inflammatory status.(2) To study the espression changes of CD47 on monocyte after burns and the correlation with cytokines, thus elucidating the role of CD47 in inflammation and drawing off possible interventions in the treatment of burns.3. Materials and methods PartⅠBlood samples were draw from 14 patients with a burn>30%TBSA(total body surface area) at day 1,3,5,7,10 and 14 after burns. For large area burned patients, samples may be collected until the fourth week after burned. More samples may be draw if there were large operations or patient status changed suddenly. Patients were divided into two groups with burn index >50 (group A) or <40(group B). Blood samples draw from 14 volunteers were considered as control samples. ELISA was carried out using ABC-HRP kit for detecting plasma ILs, while latex boosting immune scatter turbidimetric method for CRP. SPSS was used to analyze the difference of different cytokines between different groups and time, using Mann-Whitney-u-test. Significance was considered only when P value was less than 0.05.PartⅡBlood samples were draw the same as the first part, from which monocytes were separated. After reacting with CD47 antibody, flow cytometry was used to detect fluorescence intensity of CD47 on monocytes. SPSS was used to analyze the difference of CD47 between different groups and diffeent time, using Mann-Whitney-u-test. Significance was considered only when P value was less than 0.05. Then, multiple logistic regression and curve fitting were used to develop a prediction equation for determining the likely relationship between CD47 and cytokines, thus furthering the elucidation of relationship between CD47 and inflammation.4. ResultsPartⅠIL-6,IL-8,IL-10 and CRP in plasma after burns increased greatly in different time periods comparing to the control group with P<0.005. The levels of IL-6 and IL-8 reached peak in the second week, and that of group A were higher than group B. After that the two cytokines dreased with no signifucance between groups, however, still higher than that of control group. IL-10 peaked within the first week and than dreased gradually. No significance was found between groups or periods. CRP increased greatly during 5-14days after burns and became much higher than that of the first 3 days (P<0.005) . The IL-1βlevel changed too, however, there was no significance.PartⅡThe mean fluorescence intensity of CD47 on monocytes after burns were lower than that of controls(P<0.005) during days 1-3, 5-7, 10-14 and 20 days after burns. During the first two weeks the mean fluorescence intensity changes with no significance, but it became much higher after the 20th day than before. For group A, of which the burn index was >50, the mean fluorescence intensity was lower than group B druing day 1-3 and day 5-7. Though the mean fluorescence intensity increased with the improvement of patient status, it was still lower than the normal level(P<0.05). Among all the five cytokines a correlation was found between CD47 expression and the levels of IL-8 and IL-10. The standardized coefficient of IL-8 was 0.395 and that of IL-10 was -0.303 with statistic significance. CD47 expressiong increased greatly 2 weeks after burns while cytokines dreased significantly.5. Conclusions(1) Cytokines may reflex different status of inflammation of the body. The production of cytokines was related to the severity of burns. In the acute phase the significant increased and peak of IL-10 may be related to great stress, and the inflammatory reaction may not be severe. Proinflammatory factors increased significant in the 2nd week, leading to severe inflammation and after that inflammatory reaction was attenuated with cytokines decreasing greatly.(2) The expression of CD47 on monocyte was significantly supressed after burns, and was related to the severity of burns. The more serious the disease was, the lower the expression was. To some extent, however, the expression of CD47 was related to the intensity of inflammation. At first, the serious stress led to lower CD47 expression without obvious inflammation, and then more CD47 was expressed with the potentialization of inflammation within two weeks after burns. Expression of CD47 kept increasing after 3rd week, which was related to the recovery of immune state, while inflammation was extenuated, which may be because of the supression of some cytokines by CD47. All in all, the overall expression of CD47 increased with the improvement of patient status.