The Significance Of Triggering Receptor Expressed On Myeloid Cells-1(TREM-1) In Neonatal Rats Septicemia With E.coli

Objective:Septicemia,as one of the common clinical sever diseases,is the systemic inflammatory response syndrome induced by the infection. Neonate has a high degree of susceptibility to pathogens. Septicemia is easily occured in newborn, which has a high mortality.Early diagnosis ,timely and reasonable treatment of septicemia is very necessary to current clinical work. As a natural immune system, the inherent immunity is the fist line of defense to pathogens. The macrophage is an important member of body's natural immune system, whose functional status affects the prognosis of infection directly. Triggering receptor expressed on myeloid cells-1(TREM-1),which selectively expressed on the surface of the neutrophils and monocytes–macrophages,can promote the expression of the cytokines ,such as TNF-α,IL-1βand so on.It acts as the role of excitation and enlargement of the inflammation.What's more, its soluble form sTREM-1 that existed in the body fluid also plays a part in the inflammatory response , and has the anti-inflammatory effect. In this study, we analyzed the variation of the surface TREM-1 in macrophage and sTREM-1 in peripheral blood after establishing the model of neonatal rats septicemia with E.coli to.The all is in order to investigate the role of TREM-1 in the pathogenesis of sepsis,and try to develop a new idea of immunomodulation and intervention in sepsis.Methods: Choosing 72 7-day-old Sprague-Dawley(SD) rats with Special Pathogen Free(SPF), weight from 16g to 20g, either sex. They were divided into two groups: control group and septicemia group, with 36 neonatal rats in each group. All the rats were randomly divided into different time points of the two groups,including 2,4,8,12,24,48 hours.And there were 6 neonatal rats in each time point. We established the sepsis model with the method of intraperitoneal injection of E.coli.And the control group rats were injected with the same amount of normal saline. At each target time point,we got the blood from heart after anesthetizing animals,and the lungs and livers were fixed in formalin for analysis. Immunohistochemistry was chosen to analyze the expression of TREM-1 on the cell surface of macrophage in the lungs and livers. ELISA assay was used to detect the levels of sTREM-1 in plasma.Results: 1. In the control group of neonatal rats, the expression level of surface TREM-1 in macrophages of the lungs and livers and the plasma sTREM-1 at each time point had no significant difference(P>0.05);2.In the group of septicemic neonatal rats,the expression level of surface TREM-1 in macrophages and also the plasma sTREM-1 increased gradually with the experimental time prolonged.They reached the peak time at the 12th hour,then descended but remained at a high level until the 48th hour;3. At the second experimental hour, when compared to the control group,the expression level of surface TREM-1 in macrophages and also the plasma sTREM-1 of the sepsis group showed no significant difference (P > 0.05);At the fourth hour and the following experimental hours,the expression level of sepsis group was higher than control group,and the difference was statistically significant(P<0.01).Conclusion:1. With the progress of the experiment, the expression level of surface TREM-1 in macrophages of the lungs and livers and the plasma sTREM-1 of the neonatal rats had significant difference between the control group and the sepsis group,which indicated that TREM-1 played an important role in the pathogenesis of sepsis. 2. The expression level of surface TREM-1 in macrophages of the neonatal rats in sepsis group increased with time-dependent in the progress of sepsis,which suggested that the pro-inflammatory response was aggravated;And the upgrade of plasma sTREM-1 pointed that anti-inflammatory response of the body was also enhanced. 3. The expression level of surface TREM-1 in macrophages and plasma sTREM-1 changed in a parallel and equidirectional way,which was an important indication that the pro-inflammatory response and the anti-inflammatory response of the body attempted to achieve the dynamic balance. 4. On these grounds, TREM-1 can be used as a diagnostic marker for sepsis.And we try to develop a new idea of immunomodulation and intervention in sepsis.