The Expression And Significance Of S100A12in Neonatal Rats Sepsis

Objective: Calcium-binding protein S100A12plays important role in inflammation. In thisstudy, we establish the model of neonatal rats’ sepsis to observe the variation of serumconcentrations in sepsis, to analysis the corelation between S100A12and Receptor foradvanced glycation end-products(RAGE), Nuclear transcription factor kappa B(NF-κB),Tumor necrosis factor-α(TNF-α), Interleukin-6(IL-6) mRNA in liver.All of these are inorder to explore the role of S100A12in the pathogenesis of sepsis, and try to provide thedirection for the early diagnosis of sepsis.Methods: Choosing7-day-old Sprague-Dawley (SD) rats. They were randomlydivided into two groups: sepsis group (n=36) and control group (n=36). We establishedthe sepsis model with the method of intraperitoneal injection of lipopolysaccharide (LPS).The control group rats were injected with the same volume of the saline. Every group wasrandomly divided into2h,4h,8h,12h,24h,48h six subgroup after experiment. About1.5ml of blood sample in each subgroup was drawn from heart under anesthesia byintraperitoneally injected pentobarbital sodium, centrifuged, got the serum and liver tissue,and stored at-80℃. The level of serum of S100A12were measured by ELISAassay.RT-PCR was used to analyze the expression of S100A12mRNA, RAGE, NF-κB andTNF-α, IL-6mRNA in livers. The liver specimens were fixed in4%formaldehyde,embedded in paraffin, sectioned for5μm in thickness, and stained with hematoxylin andeosin(H&E). Histological changes were examined and scored according to pathologyscoring system.Result:1.Serum S100A12test results: Serum S100A12concentrations of sepsisgroup were significantly higher than that of the control group at each target time piont(P<0.05). There were obviously different from adjacent subgroup in sepsis group(P<0.05).Serum S10012levels rapidly increased at2nd hour, and reached peak at12th hour,andremained high level at48th hour; 2.The histopathology and pathology scorse of liver: In sepsis group, widelydegeneration, necrosis and neutrophil infiltration were found in liver at24th and48th hour.The liver histopathology score of sepsis group were significantly higher than the controlgroup (P<0.05),2h (Median:1Vs0),4h,8h (Median:2Vs0),12h,48h (Median:3Vs0),24h (Median:4Vs0). The histopathology score in liver increased at2nd hour, and reachedpeak at24th hour;3.In sepsis group, the serum S100A12levels has a positive correlation with the liverhistopathology score,(rs=0.659, P<0.01);4.The expression levels of pro-inflammatory cytokines test results in liver:1) Insepsis group, S100A12, RAGE, NF-κB p65, and TNF-α, IL-6mRNA of liver werehigher than that of the control group (P<0.05);2) The expression levels of S100A12ofsepsis group were significantly higher than the control group at each target time piont(P<0.05). There were obviously different from adjacent subgroup in sepsis group(P<0.05).The expression levels of S100A12rapidly increased at2nd hour, reached peak at8th hour,maintained a high level at48th hour;3) Positive correlation was indicated between the ofgene and protein levels of S100A12(rs=0.599, P<0.05);4) The expression levels of RAGEin two group revealed no significant difference at2nd and4th hour (P>0.05), but therewere significantly higher than the control group at the rest time pionts (P<0.05). In sepsisgroup, there were obviously different bewteen8h and4h,12h and8h,24h and12h,48hand24h subgroup (P<0.05). The expression levels of RAGE had no significant differenceswithin4th hour, presented higher level until8th hour, reached peak at12th hour, still kepthigher levels at48th hour than control group;5) The expression levels of NF-κB in twogroup revealed no significant difference at48th hour (P>0.05), but there were significantlyhigher than the control group at the rest time pionts (P<0.05). There were obviouslydifferent from adjacent subgroup in sepsis group(P<0.05). The expression levels of NF-κB p65began to increase at2th hour, presented significantly different at4th hour, reachedpeak at8th hour, returned to normal levels at48th hour;6) The expression levels of sepsisgroup were significantly higher than the control group (P<0.05). There were obviouslydifferent from adjacent subgroup in sepsis group(P<0.05).The expression levels of TNF-arapidly increased at2th hour after injection, attained peak at8th hour, degreed form12thhour, still presented slightly higher than control group;7) The expression levels of IL-6intwo group revealed no significant difference at2nd hour (P>0.05), but there were significantly higher than the control group at the rest time pionts (P<0.05). There wereobviously different from adjacent subgroup in sepsis group(P<0.05). The expression levelsof IL-6began to increase at4th hour, with the progresses of time, reached peak at24thhour, still kept higher expression at48th hour;8) The expression levels of S100A12inliver tissue has a positive correlation with pro-inflammatory cytokines RAGE (rs=0.511,P<0.01), NF-κB(rs=0.468, P<0.01), TNF-α(rs=0.881, P<0.01),IL-6(rs=0.521, P<0.01).Conclusion:1.With the progress of neonatal rats sepsis induced by LPS, the damageof liver gradually increased, and the expression levels of inflammatory cytokines S100A12,RAGE, NF-κB, TNF-αand IL-6increased, which indicate the over expression ofpro-inflammatory cytokines is an important cause of sepsis.2.The trend of serum S100A12protein and liver tissue S100A12mRNA levels wasconsistent in neonatal sepsis group, which suggest S100A12may play an important role inpro-inflammatory reactions.3.Serum S100A12levels was related with degree of animal liver damage in sepsis.There was a positive correlation between the expression level of S100A12in liver tissueand pro-inflammatory mediators RAGE, NF-κB, TNF-α, IL-6in the sepsis rats, whichdemonstrate S100A12may involved the synergies of inflammatory cytokines.It could beused as a new biomarker in early diagnosis of neonatal sepsis.