Expressions of Antimicrobial Peptides LL-37, Human Beta Defensin-2 and -3 in the Lesions of Cutaneous Tuberculosis and Tuberculids

BACKGROUND Antimicrobial peptides, including cathelicidin LL-37, human beta defensin (HBD)-2, and HBD-3, are important elements of the innate immune response and involved in modulation of the adaptive immunity, and they also play an important role in cutaneous defense against Mycobacterium tuberculosis. METHODS The fresh skin tissues and paraffin-embedded biopsy samples from three cutaneous tuberculosis, two tuberculids, and ten healthy individuals were collected. The expressions of LL-37, HBD-2, and HBD-3 mRNA in the lesions of three cutaneous tuberculosis and two tuberculids were detected by quantitative real-time polymerase chain reaction; the protein expressions were detected by immunohistochemistry and Western blotting methods. RESULTS The expressions of LL-37 mRNA and protein in the lesions of cutaneous tuberculosis and tuberculids were similar to that of normal skin. The expression of HBD-2 mRNA had an increasing trend in the lesions of cutaneous tuberculosis and tuberculids compared with that of normal skin; however, the expression of HBD-2 protein in the lesions of cutaneous tuberculosis had a decreasing trend compared with that of normal skin, and the expression of HBD-2 protein in the lesions of tuberculids was similar to that of normal skin. The expressions of HBD-3 mRNA and protein in lesions of cutaneous tuberculosis and tuberculids were similar to that of normal skin. CONCLUSIONS Our study indicated that the expression of HBD-2 and HBD-3 mRNA and protein in lesions of cutaneous tuberculosis may be not consistent with that of tuberculids. However, an inherent limitation of the present study was that the sample size was small, and the roles and regulation mechanisms of LL-37, HBD-2, and HBD-3 in cutaneous tuberculosis and tuberculids need to be further investigated.