The effect of Brucella outer membrane protein L16, L19 on the expression of immune regulatory factors in THP-1 cells / 中华地方病学杂志

ABSTRACT

Objective:To investigate the effect of recombinant lipoproteins of Brucella outer membrane protein 16, 19 (L16 and L19) on the expression of immune regulatory factors in human monocytic leukemia cell line (THP-1 cells). Methods:THP-1 cells activated with phorbol ester (PMA) were used as an in vitro experimental cell model, and a group design was used to co-culture L16, L19 and THP-1 cells (L16 stimulated group, L19 stimulated group), respectively. THP-1 cells activated with PMA were used as the control group. When co-cultured for 4 hours, immunofluorescence staining (IFS) and Western blotting were used to detect whether L16 and L19 entered the cells, respectively; when co-cultured for 12, 24 hours, real-time fluorescent quantitative PCR was used to measure the mRNA expression levels of interferon regulatory factor 1 (IRF-1) and trans activator protein of major histocompatibility complex class Ⅱ (CⅡTA); Western blotting was used to detect the protein expression levels of T cell immunoglobulin mucin-3 (Tim-3) and γ interferon receptor 1 (IFNGR1). Results:When co-cultured for 4 hours, L16 and L19 were observed entering THP-1 cells in the L16 stimulated group and L19 stimulated group, respectively. When co-cultured for 12 hours, the expression level of IRF-1 mRNA in the L16 stimulated group (0.16 ± 0.15) was significantly lower than that in the control group (1.00 ± 0.00, P < 0.05). When co-cultured for 24 hours, the expression level of CⅡTA mRNA in the L16 stimulated group (0.17 ± 0.10) was significantly lower than that in the control group (1.00 ± 0.00, P < 0.05). When co-cultured for 12 and 24 hours, there were no statistically significant differences in the expression levels of IRF-1 and CⅡTA mRNA between the L19 stimulated group and the control group ( P > 0.05). Western blotting results showed that there were statistically significant differences in the expression levels of INFGR1 and Tim-3 protein among the control group, L16 stimulated group, and L19 stimulated group after co-cultured for 12 and 24 hours ( F = 50.92, 6.80, 148.73, 156.57, P < 0.05). Among them, when co-cultured for 12 hours, the expression level of INFGR1 protein in the L16 and L19 stimulated groups were significantly lower than that in the control group, and the L19 stimulated group was higher than the L16 stimulated group ( P < 0.05), and the expression level of Tim-3 protein in the L19 stimulation group was higher than that in the control group ( P < 0.05). When co-cultured for 24 hours, the expression level of INFGR1 protein in the L16 and L19 stimulated groups were lower than that in the control group, and the L19 stimulated group was higher than that in the L16 stimulated group ( P < 0.05); and the expression level of Tim-3 protein in the L16 stimulated group was higher than that in the control group and L19 stimulated group ( P < 0.05). Conclusions:Brucella L16 can downregulate the expression levels of IRF-1 and CⅡTA mRNA in THP-1 cells. Both L16 and L19 can downregulate IFNGR1 and upregulate Tim-3 protein expression levels.