Toxic effects of lipoglycans of different genotypes of Mycobacterium tuberculosis on macrophages / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To detect the inflammatory reaction of macrophages induced by lipoglycans of different genotypes of Mycobacterium tuberculosis ( Mtb) in vitro and to analyze the differences in lipoglycan virulence. Methods:Lipoglycans were extracted from Mtb of Beijing, T1 and MANU2 genotypes and H37Rv by Triton X-114 liquid phase method and the crude extracts of lipoglycans was used to stimulate RAW264.7 macrophages. Changes in cytokine and receptor expression and cell apoptosis were detected 24 h after stimulation. The virulence of lipoglycans from different genotypes of Mtb was analyzed and compared. One-way analysis of variance and Tukey′s multiple comparisons test were used to compare the differences in various indexes between groups. Results:The expression of IL-10 at mRNA level induced by lipoglycans from Mtb of Beijing, T1 and MANU2 genotypes and H37Rv was (0.94±0.24), (1.86±0.24), (1.90±0.24) and (2.55±0.75) times that of the control group. Moreover, IL-10 mRNA expression induced by lipoglycans from Mtb of Beijing genotype was significantly lower than that of H37Rv group ( P<0.05). After stimulating RAW264.7 cells with the crude extracts of lipoglycans, the proportions of living cells in H37Rv, Beijing genotype, T1 genotype and MANU2 genotype groups were (72.75±2.25)%, (60.99±0.13)%, (80.66±0.40)% and (79.06±1.19)%, and the total cell apoptosis ratios was (10.42±0.23)%, (8.30±0.03)%, (9.24±0.79)% and (8.04±0.48)%, respectively. The proportion of living cells in Beijing genotype group was the lowest ( P<0.05), and the proportions of living cells in T1 and MANU2 genotype groups were higher than that in H37Rv group ( P<0.05). There was no significant difference in cell apoptosis ratio among the groups ( P>0.05). Lipoglycan-induced cell death was increased in Beijing genotype group, and the lipoglycan from Beijing genotype Mtb was more virulent than those from Mtb of T1 and MANU2 genotypes. Conclusions:Lipoglycan from Mtb of Beijing genotype could induce a higher level of cell death in vitro. It was an antigen component with stronger virulence than those from Mtb of T1 and MANU2 genotypes.