OBJECTIVE To explore the influence of glucuronoxylomannan (GXM) of Trichosporon asahii on Toll-like receptor (TLR)-2, TLR-4 and TLR-6 in human myeloid leukemia mononuclear cell (THP-1) and analyze the molecular mechanisms.

METHODS The THP-1 cells were randomly divided into the blank control group (without any treatment after the culture of induced and differentiated THP-1 cells for 8 and 24 hours), and the GXM group (with the induced and differentiated THP-1 cell acting by 500 μg/ml of T. asahii GXM for 8 and 24 hours) after being induced differentiation with phorbol 12-myristate 13-acetate (PMA). The expression levels of TLR-2, TLR-4 and TLR-6 messager ribonucleic acid (mRNA) were detected by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR), and the expression level of TLR-2 protein was detected by means of Western Blot (WB).

RESULTS The expression levels of TLR-2, TLR-4 and TLR-6 mRNA of the GXM group were 0.65±0.05, 0.46±0.03 and 0.51±0.19, respectively, after the THP-1 cells were acted with GXM for 8 hours, lower than those of the blank control group(P<0.05). After being acting with GXM for 24 hours, the expression level of TLR-2 mRNA of the GXM group was 0.83±0.05, lower than that of the blank control group(t=4.927, P=0.039), and there were no significant differences in the expression levels of TLR-4 and TLR-6 mRNA between the GXM group and the blank control group. The expression level of TLR-2 protein of the GXM group was 85.43±0.40 after the THP-1 cells were acted with GXM for 24 hours, lower than that of the blank control group (t=35.415, P<0.001).

CONCLUSION The T. asahii may possess the capabilities of escaping from the phagocytosis of white blood cells and monocytes by increasing the release of GXM, which may help a certain number of fungi escape from the killing by the immune system of the host and establish the persistent infection.