Implication Of Leukotriene B₄ (LTB₄)-leukotriene B₄ Receptor (BLT) Pathway In The Pathogenesis And Treatment Of Kawasaki Disease

ObjectiveTo investigate the effect of the serum taken from patients with acute Kawasaki disease andγ-globulin on the expressions of BLT1 at the level of mRNA and LTB4 production in endothelial cell. Meanwhile, the effects of the endothelial cell conditioned culture media (ECM) on the expression of BLT2 in macrophage were observed. This study aimed at exploring whether LTB4-BLT pathway is involved in endothelial damage in Kawasaki disease and the mechanism ofγ-globulin in the treatment of Kawasaki disease.Methods1. Groups of cultured endothelial cell (ECV304): A. normal serum group: RPMI1640 culture medium+10% blood serum of healthy children. B. blood serum of KD group: RPMI1640 culture medium+10% blood serum of KD. C.γ-globulin group: RPMI1640 culture medium+10% blood serum of KD+γ-globulin (20mg/ml). The cells in each group were cultured for 24h and 48h, then dissolved with TRIzol. The culture medium in each group was collected before and after cultured.2. The mRNA levels of BLT1 were amplified by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Products were segregated by agarose gel electrophoresis. Gel imaging analysis device was used to analyze the results of the agarose gel electrophoresis. The results were indicated by optical density of the BLT1/β-actin.3. The concentration of LTB4 in the supernatant was determined by ELISA before and after cultivation of 48h.4. Balb/c mouse macrophages were separated and cultured in conditioned media containing the serum of KD orγ-globulin. The macrophages were cultured for 24h and prepared by 0.25% trypsin in each ECM.5. The expression of BLT2 in the macrophage was determined by flow cytometry.Results1. The expression of BLT1 in the ECV304 was upregulated 24h and 48h after the stimulation by the serum of Kawasaki disease(p<0.05), but was not significantly upregulated in either normal serum group orγ-globulin group.2. The concentration of LTB4 in the endothelial cell culture was significantly increased by the serum of patients with KD(p<0.05 VS normal control), but not by normal conditioned media orγ-globulin conditioned media.3. The expression of BLT2 in the macrophage was enhanced significantly(p<0.05 VS normal control)by the serum of patients with KD. But such effect was abolished by addition ofγ-globulin.ConclusionsIt is assumed that LTB4-BLT pathway is involved in vascular damage in Kawasaki disease, and blocking the LTB4-BLT pathway may be one of the mechanism ofγ-globulin to treat Kawasaki disease.