The HIV protease inhibitor lopinavir/ritonavir (Kaletra) alters the growth, differentiation and proliferation of primary gingival epithelium

Objective: This study was designed to evaluate the effects of the HIV protease inhibitor lopinavir/ritonavir on gingival epithelium growth, integrity and differentiation. Methods: Organotypic (raft) cultures of gingival keratinocytes were established and treated with a range of lopinavir/ritonavir concentrations. To examine the effect of lopinavir/ritonavir on gingival epithelium growth and stratification, haematoxylin and eosin staining was performed. To investigate the effect of this drug on tissue integrity, transmission electron microscopy (TEM) was performed on untreated and drug-treated tissues. Further, immunohistochemical analysis of raft cultures was performed to assess the effect of lopinavir/ritonavir on the expression of key differentiation and proliferation markers including cytokeratins, proliferating cell nuclear antigen (PCNA) and cyclin A. Results: Lopinavir/ritonavir treatments drastically inhibited the growth of gingival epithelium when the drug was present throughout the growth period of the tissue. When the drug was added on day 8 of tissue growth, lopinavir/ritonavir treatments compromised tissue integrity over time and altered the proliferation and differentiation of gingival keratinocytes. Expression of cytokeratins 5, 14, 10 and 6, PCNA and cyclin A was induced, and their expression patterns were also altered over time in treated rafts. Conclusions: The findings of our studies suggest that lopinavir/ritonavir treatments compromised tissue integrity over time and deregulated the cell cycle/proliferation and differentiation pathways, resulting in abnormal epithelial repair and proliferation. Our study provides a model of potential utility in studying the effects of antiretroviral drugs in vitro.