title: Causes of immune dysfunction in hyperbilirubinemia model rats.
abstract: OBJECTIVE
  To explore the causes of immune dysfunction in neonatal rats with hyperbilirubinemia.
  
  
  METHODS
  A total of 60 newborn SD rats were equally randomized into normal saline (NS) group, LPS control group, bilirubin control group, low-dose group and high-dose group. After anesthesia, 0.1 mL NS was given to the NS and LPS control group and different doses of bilirubin for the other groups; 1 h later, the NS and bilirubin control group received the intraperitoneal injection of 0.05 mL NS and 1mg/kg LPS for the other groups. After 5 or 24 hours of model establishment, spleens were collected for detecting the expression levels of MyD88 and p-TAK1 protein and the spleen cells apoptosis by immunohistochemmistry and TUNEL method. After 24 hours of model establishment, serum inflammatory factors levels and T cell subsets distribution were determined by ELISA and flow cytometry.
  
  
  RESULTS
  In contrast to low-dose bilirubin, high-dose bilirubin could induce spleen cells apoptosis in coordination with LPS. After 5 hours of model establishment, compared with NS group, MyD88 expression level in low-dose group elevated while p-TAK1 level in high-dose group reduced (P<0.05). In high-dose group, inflammotory factors levels and CD8(+) T cells percentage were all higher than LPS control and NS group (P<0.05), while CD4(+) T cells percentage was lower than NS group (P<0.05).
  
  
  CONCLUSIONS
  High-concentration plasma bilirubin in coordination with LPS could inhibit NF-κB signal pathways activation and aggravate inflammatory reaction, thus caused immunosuppression with inflammation cascade, which resulted in the immune dysfunction.
authors.affiliation: Department of General Internal Medicine, Children's Hospital of Zhengzhou, 450000, Zhengzhou City, Henan Province, China.
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Sun
authors.affiliation: Department of General Internal Medicine, Children's Hospital of Zhengzhou, 450000, Zhengzhou City, Henan Province, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Kang
authors.affiliation: Burn Center of PLA, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, P.R. China. Electronic address: stt507@163.com.
authors.forename: Ke
authors.initials: K
authors.lastname: Tao
keywords: Bilirubin; Hyperbilirubinemia; Myd88; Spleen cells; p-p38MAPK