The aim of the current study was to evaluate secretory leukocyte protease inhibitor (SLPI) expression in anal biopsies from HIV-positive (HIV) individuals, and compare that to anal intraepithelial neoplasia (AIN) diagnoses and human papillomavirus (HPV) status.
This is a cross-sectional study of a cohort of 54 HIV (31 males and 23 females) from an AIDS clinic in Rio de Janeiro, Brazil.
The study material consisted of anorectal tissue biopsies obtained from HIV subjects, which were used to construct tissue microarray paraffin blocks for immunohistochemical analysis of SLPI expression. Biopsies were evaluated by an expert pathologist and classified as low-grade anal intraepithelial neoplasia (AIN1), high-grade anal intraepithelial neoplasia (AIN2/3), or normal squamous epithelium. Additionally, DNA from the biopsies was extracted and analyzed for the presence of low- or high-risk HPV DNA.
Histologically normal squamous epithelium from the anorectal region showed strong positive SLPI staining in 17/20 (85%) samples. In comparison, 9/17 (53%) dysplastic squamous epithelial samples from AIN1 patients showed strong SLPI staining, and only 5/17 (29%) samples from AIN2-3 patients exhibited strong SPLI staining, which both were significantly fewer than those from normal tissue (p=0.005). Furthermore, there was a significantly higher proportion of samples in which oncogenic high-risk HPV genotypes were detected in low SLPI expressing tissues than that in tissues with high SLPI expression (p=0.040).
Taken together these results suggest that low SLPI expression is associated with high-risk HPV infections in the development of AIN.