The Effect Of Bilirubin On Inflammatory Signaling Pathway Mediated By NOD-like Receptors And Antimicrobial Immunityin Premature Infants

Objective:To compare the difference of NOD-like receptors(NLRs)(NOD1,NOD2)and IL-6,TNF-α in preterm infants with different gestational age and birth weight.To observe the effect of bilirubin on NOD1,NOD2,IL-6,TNF-α.To evaluate the relationship between gestational age,birth weight and immune function and the effect of bilirubin on inflammatory signaling pathway mediated by NOD-like receptor and antimicrobial immunity in premature infants.Methods:The peripheral blood 1ml of 55 cases premature infants were collected and divided into different groups according to gestational age and birth weight.Then the mononuclear cells were isolated and stimulated 24 h by Tri-DAP and MDP.In addition,2ml peripheral blood were collected from 30 cases of premature infants,divided into Tri-DAP and MDP group randomly,isolated mononuclear cells and divided into 6 subgroups,namely the control group(A),Tri-DAP/MDP group(B),6mg/dl bilirubin(C),6mg/dl bilirubin +Tri-DAP/MDP(D),9mg/dl bilirubin+Tri-DAP/MDP(E),15mg/dlbilirubin +Tri-DAP/MDP(F);incubated 1h with different concentration of bilirubin,and then stimulated by Tri-DAP and MDP for 24 h.Collected the cells and supernatant respectively,the expression of NOD1,NOD2 were determined by RT-PCR,IL-6 and TNF-α were determined by ELISA.Results:1.Preterm infants with gestational age<32w NOD1 was significantly lower than that of 34w-36w;After stimulated by MDP,the expression of IL-6 with gestational age <32w were significantly lower than that with 34w-36 w.2.NOD1 gene with birth weight<1500g was significantly lower than that with 1500g-2000 g and 2000g-2500 g and NOD2 was significantly lower than that with2000g-2500 g.The expression of IL-6 in the preterm infants with birth weight<1500g was significantly lower than 2000g-2500 g after stimulated by Tri-DAP and MDP.3.The expression of NOD1 and NOD2 was positively correlated with birth weight,but had no correlation with gestational age.4.NOD1 and NOD2 were not significantly changed after stimulated by Tri-DAP,MDP or bilirubin.5.After stimulated by Tri-DAP,MDP or 6mg/dl bilirubin,IL-6,TNF-α had no obviously change,but was significantly decreased after stimulated by 9mg/dl and 15mg/dl bilirubin.Conclusions:1.Smaller gestational age,lower birth weight,lower NLRs,weaker the ability of antimicrobial,especially that with gestational age <32w or birth weight<1500g,which may imply that an important pathology mechanism that the premature infants are vulnerable to infection complications.2.The correlation between birth weight and NLRs was significant.In the same gestational age,the expression of NLRs was lower in preterm infants with lower birth weight,which may be one of the reasons for the lower immune function in small for gestational age.3.Bilirubin had no significant affect on the expression of NLRs in premature infants.4.High concentration of bilirubin inhibited the secretion of cytokines,speculated that high bilirubin in the blood may inhibit the signal transduction pathway to inhibit the body’s immune function.