Comparative Analysis of Cytokine Expression in Oral Keratinocytes and THP-1 Macrophages in Response to the Most Prevalent Serotypes of Aggregatibacter actinomycetemcomitans

Abstract

Background: Periodontitis is a chronic inflammatory disease associated with a dysbiotic biofilm. Many pathogens have been related with its progression and severity, one of which is Aggregatibacter actinomycetemcomitans, a Gram-negative bacteria with seven serotypes (a–g) according with the structure of its LPS, with serotype b defined as the most virulent compared with the other serotypes. The aim of this study was to evaluate the response of oral keratinocytes and macrophages to A. actinomycetemcomitans. Methods: Oral keratinocytes (OKF6/TERT2) and macrophages (THP-1) were infected with A. actinomycetemcomitans serotypes a, b and c. The expression of IL-1β, IL-6, IL-8, IL-18, TNF-α, MMP-9, RANKL, TLR-2, TLR-4, TLR-6, thymic stromal lymphopoietin (TSLP), and ICAM-1 was evaluated by qPCR at 2 and 24 h after infection. Results: An increase in the expression of these molecules was induced by all serotypes at both times of infection, with macrophages showing higher levels of expression at 24 h compared to epithelial cells in which the highest levels were observed in the first hours after infection. Conclusions: Keratinocytes and macrophages contribute to the inflammation in periodontitis from the early stages of infection, producing the first waves of cytokines, acting as the first signal for professional immune cell recruitment and modulation of more specific immune responses.

Association of Periodontitis and Atopic Dermatitis with the Levels of IL-13, IL-31, and TSLP in the Gingival Crevicular Fluid

“…Supporting this idea, in vitro studies have found that stimulation with Aggregatibacter (A.) actinomycetemcomitans, a key periodontal pathogen, leads to an increase in the TSLP mRNA expression in epithelial cells and macrophages as compared to unstimulated cells [59]. Moreover, a study reported a detection frequency of 5.9% for TSLP in inflamed periodontal sites of patients with gingivitis and 9.1% in inflamed periodontal sites of patients with periodontitis.…”

“…The role of TSLP in periodontal tissues remains unclear; nonetheless, it is possible that the cytokine participates in periodontitis progression [59]. Supporting this idea, in vitro studies have found that stimulation with Aggregatibacter (A.)…”

Differential Virulence of Aggregatibacter actinomycetemcomitans Serotypes Explained by Exoproteome Heterogeneity

“…This contrasts to some extent with the results from other previous studies, where Aa isolates with serotype b were shown to display a higher in vitro virulence toward immune and nonimmune cells than Aa isolates with other serotypes ( 21 , 61 , 62 ). Furthermore, it has been reported that the virulence of Aa toward oral epithelial cells and macrophages may not follow serotype-specific patterns ( 63 ). It is presently difficult to reconcile these different observations, but they may relate to the usage of different isolates and strains, as well as different infection models and culture conditions.…”

SAP deficiency aggravates periodontitis possibly via C5a-C5aR signaling-mediated defective macrophage phagocytosis of Porphyromonas gingivalis

“…Interaction between pathogenic bacteria and host immune cells is a key process of periodontitis progression. Macrophages are major immune cells of innate immunity [17] and participate in periodontitis pathogenesis by regulating periodontal biofilm, activating adaptive immunity, and mediating the absorption and repair of alveolar bone [18] , [19] . Macrophages are classified as pro-inflammatory macrophages (M1) and anti-inflammatory macrophages (M2) according to their immunomodulatory functions.…”