Human papillomavirus-associated induction of human β-defensins in anal intraepithelial neoplasia

Background Antimicrobial peptides and proteins (AMPs) are widely distributed effector molecules of the innate immune system with well-known antibacterial activity. However, there is a paucity of information regarding antiviral effects of AMPs.

Objectives The present study was performed to analyse expression of AMPs in human papillomavirus (HPV)-associated anal skin lesions of human immunodeficiency virus (HIV)-positive men who have sex with men (MSM), a special high-risk group for persistent HPV infections and anal dysplasia.

Methods Skin lesions were analysed for the presence of LL-37, RNase 7, and human β-defensin (hBD)-1, hBD-2 and hBD-3. Moreover, HPV typing and HPV DNA load determination for HPV types 6, 11, 16, 18, 31 and 33 were performed to evaluate possible correlations between expression of AMPs and lesional HPV types.

Results Skin biopsies of 45 HIV-positive MSM with anal intraepithelial neoplasia (AIN), anal condylomata acuminata or unaffected anal mucosa, as well as condylomata acuminata of eight HIV-negative MSM, were analysed for AMP mRNA expression. Additionally, immunohistochemical analysis for hBD-2 and hBD-3 was performed in a total of 45 samples. hBD-2 and hBD-3 gene and protein expression was significantly increased in both AIN and condyloma, whereas LL-37, RNase 7 and hBD-1 gene expression did not differ significantly from unaffected anal mucosa. AMP expression correlated neither with the number of HPV types nor with the high-risk and low-risk HPV DNA loads of the quantified types. No significant differences in AMP expression were observed in condylomata of HIV-positive and HIV-negative MSM.

Conclusions hBD-2 and hBD-3 expression was shown to be significantly upregulated in HPV-associated anal skin lesions of both HIV-positive and HIV-negative MSM. Their biological significance in the innate immunity against these lesions needs further research.