Increased toll-like receptor 9 expression in cervical neoplasia

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns (PAMPs) and enable innate immune responses. Although TLR9 has been previously considered to be expressed only in immune cells, there is now increasing evidence that TLR9 expression is present in nonimmune cells as well. In this study, we undertook to determine whether TLR9 expression was associated with disease progression in cervical neoplasia. TLR9 expression was evaluated by immunohistochemistry in 55 formalin-fixed paraffin-embedded cervical tissues; nine normal cervical specimens, 10 low-grade cervical intraepithelial neoplasias (CINs), 12 high-grade CINs, and 24 invasive squamous cell carcinomas (ISCCs). In addition, TLR9 expression was evaluated, at the RNA level, in fresh frozen cervical carcinoma tissues by real-time quantitative RT-PCR. Immunohistochemical staining showed that TLR9 expression was undetectable (55.6%) or weak (44.4%) in normal cervical squamous epithelial tissues, however, variable staining was observed in the basal layer of all normal endocervical glands. TLR9 expression, which was mainly observed as cytoplasmic staining, gradually increased in accordance with the histopathological grade in the following order: low-grade CIN