ABSTRACT
BACKGROUND AND OBJECTIVE: Gingival keratinocytes are used in model systems to investigate the interaction between periodontal bacteria and the epithelium in the initial stages of the periodontal disease process. Primary gingival epithelial cells (GECs) have a finite lifespan in culture before they enter senescence and cease to replicate, while epithelial cells immortalized with viral proteins can exhibit chromosomal rearrangements. The aim of this study was to generate a telomerase immortalized human gingival epithelial cell line and compare its in vitro behaviour to that of human GECs. MATERIAL AND METHODS: Human primary GECs were immortalized with a bmi1/hTERT combination to prevent cell cycle triggers of senescence and telomere shortening. The resultant cell-line, telomerase immortalized gingival keratinocytes (TIGKs), were compared to GECs for cell morphology, karyotype, growth and cytokeratin expression, and further characterized for replicative lifespan, expression of toll-like receptors and invasion by P. gingivalis. RESULTS: TIGKs showed morphologies, karyotype, proliferation rates and expression of characteristic cytokeratin proteins comparable to GECs. TIGKs underwent 36 passages without signs of senescence and expressed transcripts for toll-like receptors 1-6, 8 and 9. A subpopulation of cells underwent stratification after extended time in culture. The cytokeratin profiles of TIGK monolayers were consistent with basal cells. When allowed to stratify, cytokeratin profiles of TIGKs were consistent with suprabasal cells of the junctional epithelium. Further, TIGKs were comparable to GECs in previously reported levels and kinetics of invasion by wild-type P. gingivalis and an invasion defective ΔserB mutant. CONCLUSION: Results confirm bmi1/hTERT immortalization of primary GECs generated a robust cell line with similar characteristics to the parental cell type. TIGKs represent a valuable model system for the study of oral bacteria interactions with host gingival cells.
Subject(s)
Gingiva/cytology , Adult , Cell Count , Cell Culture Techniques , Cell Line, Transformed , Cell Proliferation , Cell Shape/physiology , Cellular Senescence/physiology , Epithelial Attachment/cytology , Epithelial Cells/cytology , Epithelial Cells/microbiology , Gingiva/microbiology , Humans , Karyotype , Keratin-13/metabolism , Keratin-14/metabolism , Keratin-19/metabolism , Microscopy, Confocal , Microscopy, Fluorescence , Polycomb Repressive Complex 1/genetics , Porphyromonas gingivalis/physiology , Retroviridae/genetics , Telomerase/genetics , Telomere/physiology , Toll-Like Receptors/metabolism , Transduction, Genetic , Zinc Fingers/geneticsABSTRACT
Because recognizing depression is of critical importance, we have organized a comprehensive review of current literature on medical, psychiatric, and behavioral science to give primary care physicians a brief, practical, and multidisciplinary survey of diagnostic approaches to depression. The review is also designed to help clarify the disparate approaches, definitions, theories, and classifications of depression found in the literature. We emphasize two emerging perspectives important to primary care physicians in their understanding and treatment of depression. The first is a wider view of masked depression, and the second is depressive behavior related to family and cultural systems. Traditional classifications may have limited applicability to the patient families most often seen in primary care. We hope that the paper will serve as a challenge to physicians to combine open and creative observation with inductive reasoning in the creation of a more useful system for classifying depression in primary care.
