Abstract:

Objective To observe the expression of Toll-like receptors （TLRs） 2, 4 and 9 in lesions of lupus vulgaris and tuberculosis verrucosa cutis, and to evaluate the possible roles of these receptors in the pathogenesis of cutaneous tuberculosis. Methods Skin specimens were obtained from the lesions of 18 patients with clinically and pathologically diagnosed lupus vulgaris or tuberculosis verrucosa cutis, 15 patients with plaque-type psoriasis （positive control）, and from perilesional normal skin of 10 patients with pigmented nevi （negative control）. Immunohistochemistry was used to detect the expression of TLRs 2, 4 and 9 in these specimens, and the expression intensity was expressed as absorbence values. Data were analysed by using the SPSS 13.0 software, and t test was conducted to assess the differences between the three groups of specimens. Results TLR-2 was observed mainly in the middle and upper layer of epidermis in lesions of cutaneous tuberculosis and psoriasis, and in the whole epidermis except the basal layer in normal skin, with no significant difference in the expression intensity between the three groups of specimens（0.25 ± 0.04 vs. 0.25 ± 0.05 vs. 0.28 ± 0.03, P > 0.05）. TLR-4 was weakly expressed in cutaneous tuberculosis lesions, absent or slightly expressed in normal skin and psoriatic lesions, and the expression level of TLR-4 was significantly higher in cutaneous tuberculosis lesions than in normal skin and psoriatic lesions （0.16 ± 0.07 vs. 0.07 ± 0.09 and 0.02 ± 0.05, t = 2.58, 6.24, P ＜ 0.01 and 0.05）. TLR-9 was expressed in the whole epidermal layer, including appendages and vascular walls, of cutaneous tuberculosis and normal skin, with a significant increase in cutaneous tuberculosis than in the normal skin （0.25 ± 0.05 vs. 0.19 ± 0.05, t = 2.88, P ＜ 0.05）. Conclusions TLRs 2, 4 and 9 are all expressed in cutaneous tuberculosis lesions, and the expression intensity of TLR-4 and TLR-9 is higher in cutaneous tuberculosis lesions than in normal skin, hinting that TLR-4 and TLR-9 play a certain role in the immune response of cutaneous tuberculosis.

Key words: Expression