Assessment of Apical Expression of Alpha-2 Integrin, Heat Shock Protein, and Proinflammatory and Immunoregulatory Cytokines in Response to Endodontic Infection

• We show proinflammatory mediators decrease after root canal cleaning procedures 1 week after chemomechanical debridement.
• We examine changes in the messenger RNA expression of the integrins SSP1/OPN and FAK as well as Hsp47/SERPINH1 and ITGA2 in samples from the periapical area.
• The regulatory cytokine IL-10 was higher in samples from the second collection (after cleaning procedures) compared with the first collection.
• The expression of the genes described here suggested an ongoing healing process after reduction of the bacterial load by root canal cleaning.

IntroductionThe purpose of this study was to examine alpha-2 integrin, molecular mediators, cytokines, and chemokines from cells in periapical interstitial fluid from root canal infections before and after the reduction of the bacterial load using a cleaning procedure.MethodsSubjects included 20 patients referred to the School of Dentistry at the Universidade Federal de Minas Gerais (Belo Horizonte, Minas Gerais, Brazil). Clinical samples were taken from teeth with pulp necrosis, and no patients had acute periapical symptoms at the time of the appointments. After cleaning and drying, 3 paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 minute. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions using real-time polymerase chain reaction.ResultsSignificantly lower levels of tumor necrosis factor alpha, chemokine ligand 5 (CCL5), chemokine ligand 2/monocyte chemotactic protein 1 (CCL2/MCP-1), and interleukin (IL)-8 in teeth with restrained bacterial loads (second collection) compared with the first collection were observed (P < .05). Similarly, the messenger RNA expression of the integrins secreted phosphoprotein 1 (SSP1)/ostepontin and focal adhesion kinase (FAK) decreased in samples from the second collection (P < .05). The messenger RNA for the regulatory cytokine IL-10 was significant higher in samples from the second collection (day 7) compared with the first collection (day 0) (P < .05). Messenger RNA expression of IL-1β, IL-17A, interferon gamma, alpha-2 integrin, and Hsp47/SERPINH1 were similar at both time points (P > .05).ConclusionsThese findings suggest that after reducing the root canal bacterial load a decrease in the inflammatory response took place in the periapical lesions.