MMP-9 expression increases according to the grade of squamous intraepithelial lesion in cervical smears

Studies about cervical carcinogenesis have demonstrated the increased expression of matrix-metalloproteinase (MMP) according to the grade of cervical intraepithelial lesions. Considering the importance of innovative techniques to introduce noninvasive and rapid diagnoses for patients, this study aimed to perform MMP-9 immunocytochemistry in cervical smears according to the cytopathological diagnoses, in order to monitor MMP activity in cervical smears. This cross-sectional study investigated the expression of MMP-9 in normal cervical smears, inflammatory cervical smears, squamous intraepithelial lesions, and cervical carcinoma. Cervical smears from 630 women were collected for cytopathological diagnoses and immunocytochemistry. Women with squamous intraepithelial lesions showed an increase in MMP-9 expression, with moderate to intense staining occurring with increasing cervical lesion grade. The prevalence of moderate to intense MMP-9 staining was 9% in normal cervical smears, 12% in cervical inflammation, 24% in low-grade squamous intraepithelial lesion (LSIL), 92% in high-grade squamous intraepithelial lesions (HSIL) and 100% in cervical carcinoma cases. In the specific case of LSIL, we found that association with MMP-9 is more evident when there is the simultaneous presence of an infectious agent. Thus, the expression of MMP-9 in cervical smears increases according to the grade of cervical lesion and LSIL in the presence of infectious agents showed higher MMP-9 expression than women with LSIL without infectious agents.