Resumen
Objective: Cluster of differentiation (CD14) is an important protein involved in activating toll-like receptors by bacterial components. It exists as either a transmembrane or soluble protein, called mCD14 or sCD14, respectively. Several studies show that CD14 regulates the inflammatory response to periodontal pathogens, and its expression is altered in periodontitis, an inflammatory disease of tooth-supporting tissues. It is the intent of this review to investigate the levels of expression of mCD14 and sCD14 in peripheral blood monocytes, saliva, gingival crevicular fluid, and gingival tissue biopsies in periodontitis patients. Methods: PubMed, Scopus, Ovid/Medline, Embase, and the Cochrane Library were consulted for the online literature search. To ensure methodical quality, titles and abstracts were reviewed in accordance to the PRISMA guidelines. Data extraction and evaluation of the full texts were executed in agreement with the GRADE approach. Results: This systematic review shows that mCD14 levels are decreased in peripheral blood monocytes of periodontitis patients in comparison to healthy patients, while sCD14 levels in sera, gingival crevicular fluid (GCF), and biopsies of periodontitis patients have a tendency to be increased in comparison to healthy controls. The evaluation of CD14 in gingival biopsies and periodontal tissues elucidated the fact that interpretation of the data obtained with qPCR, ELISA, and flow cytometry is questionable.