| ObjectiveThe aim of this study was to examine angiopoietin-2(Ang-2) level in two different rat models of sepsis induced by cecal ligation and puncture (CLP) during the course of disease, so as to draw the fluctuation curves of serum Ang-2level. Compare the difference of Ang-2level between two different groups of rat model and; Preliminarily discusses the relation of Ang-2level and sepsis-induced acute lung injury, meanwhile provide a foundation for clinical research.MethodsSixty-two male SD rats weighing180-200g were randomly divided into two parts, part I was used to draw the fluctuation curves of serum Ang-2level, thirty-two SD rats were randomly divided into4groups; control group(n=6), din’t do any processing after giving anesthesia; sham-operated group(n=6), closed abdomen directly After turning of cecum, sepsis-1group(n=10), ligature the cecum distal1cm after CLP and16G needle puncture the cecum once; sepsis-2group (n=10) ligature the cecum distal2cm after CLP and16G needle puncture the cecum two times. Inner canthus blood samples were collected just on the time of onset and31h、6h、12h、18h、24h、36h、48h、72h after CLP, Ang-2levels in the supernatant after centrifuge were measured by using enzyme linked immunosorbent assay to observe the dynamic change rule. Part II was used to search the relation of Ang-2level and sepsis-induced ALI. Thirty rats were randomly divided into5groups (n=6each); copy the sepsis-induced acute lung injury rat models, the way is the same to sepsis-2group. The five groups were L0, L3, L6, LI2, LI8; the abdominal aorta blood samples were collected just on the time of onset and3h,6h,12h,18h after CLP, rats of every group were sacrificed to measure Ang-2levels by enzyme linked immunosorbent assay, analyse arterial blood, weigh the lung and compute the lung coefficient, observe the degree of lung tissue injury by pathological section. Using SPSS17.0for data processing and statistical analysis, The qualitative data analysed by chi-square test, Quantitative data using t or F test, compare the Ang-2level of different time using repeated measurement data analysis of variance. P<0.05for the difference is statistically significant.Results1. There were no dead rats within72hours in control group and sham-operated group, the mortality rate is0%. There were no dead rats within16hours, two dead rats within24hours, three dead rats within72hours in sepsis-1group,24-hour mortality is20%,72-hour mortality is30%. In sepsis-2group, there were no death within16hours, nine dead rats within24hours, ten dead rats within72hours,24-hour mortality is90%,72-hour mortality is100%. The24-hour mortality and72-hour mortality of S2-group is higher than that of Sl-guoup with statistical significance (P<0.01). In part II, the rats of L12developed breathing difficulties, diarrhea, ears skin pale, Tail cold, acrocyanosis, there was purulent fluid and bad smells in enterocoelia, the cecum distal ligatured go black and had some adhesion with adjacent tissue, the lung show oedema and congestion, Oxygenation index less than300, pulmonary pathology show thickening of the alveolar interval, pulmonary interstitial show hyperemia and dropsy, leukocytes accumulation, alveolar collapse, secreta in airways, all of these indication show the sepsis-induced acute lung injury rat models were copied successfully.2. The dynamic change of serum Ang-2level in every rat models:in control group, the fundamental level is (1.57±0.09) ng/mL,there was no significant change during the progression of sepsis. In sham-operated group, the fundamental level is (1.55±0.32)ng/mL,(2.09±0.20)ng/mL at6hours, it peaked to (2.65±0.23) ng/mL at12hours, back to the basic level at48hours and go down to72hours. In sepsis-1group, the fundamental Ang-2level is (1.67±0.18) ng/mL, significantly rised at3hours, peaked to (3.57±0.39) ng/mL at12hours, down to the lowest level (2.08±0.21) ng/mL at48hours but remain higher significantly than fundamental level. In sepsis-2group, most of the rats have died after18hours, so the curve extend to18hours, the fundamental Ang-2level is (1.56±0.16) ng/mL, significantly rised at3hours, peaked to (3.44±0.42) ng/mL at12hours, until18hours remain higher significantly than fundamental level. From the fluctuation curves of serum Ang-2level we can see that there was no significant difference between sepsis-1group and sepsis-2group at each timing, but the serum Ang-2level of two septic group was significantly higher than control group and sham-operated group, with statistical significance, the serum Ang-2level reached a peak at12hours in all groups.3. In part II, the oxygenation index, pulmonary index have no significant difference in the groups of L0, L3, L6(P>0.05), lung tissue pathology show that the tisue gradation is distinct, a few inflammatory cells infiltrate, The alveolar structure is integrated, there is no edematous fluid in pulmonary alveoli; in L12group, the oxygenation index less than300, pulmonary index was higher than that of LO group, with statistically significant difference (P<0.01), lung tissue pathology show that alveolar wall tissue get thicker, alveolar interstitial get hyperemia and oedema, some inflammatory cells infiltrate, a few alveolar collapse, lung tissue pathology show that the alveoli septum get thickened observely, the structure get disturbed, there were congestion, edema of pulmonary interstitial, a lot of inflammatory cells infiltrate, a large number of alveolar atrophy, within the airway is full of red discharge. The Ang-2levels is (1.49±0.21) ng/mL in LO group, that is lower than L3group (2.34±0.25) ng/mL, with statistically significant difference (P<0.05), L6group higher than L3group significantly, it reach highest level in L12group (3.47±0.41) ng/mL, the L18group lower than L12group, but remain higher than LO group, with statistically significant difference (P<0.01) ConclusionsThe expression of Ang-2have certain regularity in the course of sepsis rat model, began to rise at3hours, peaked at12hours, and since fallen, but also higher than fundamental level. Serum Ang-2level rise significantly before sepsis-induced acute lung injury, after the expression peak, the sepsis-ALI emerge, so Ang-2may participate in sepsis-ALI disease process and it could become a early biomarker of sepsis or sepsis-ALI. |
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