Immune Response Profile against Persistent Endodontic Pathogens Candida albicans and Enterococcus faecalis In Vitro Stella Maris de Freitas Lima, MSc,* † Maur  ıcio Gonc ¸alves da Costa Sousa,* ‡ Mirna de Souza Freire, MSc,* § Jeeser Alves de Almeida, PhD,* jj Ana Paula de Castro Cantu aria, DSc,* ‡ Tha  ıs Ang elica Machado e Silva, DDS,* † Camila Guimar~ aes de Freitas, MSc,* ¶ Simoni Campos Dias, PhD,* Oct avio Luiz Franco, PhD,* ** and Taia Maria Berto Rezende, PhD* †‡ Abstract Introduction: Persistent microorganisms such as Candida albicans and Enterococcus faecalis might be directly related to endodontic treatment failure. The host response to these microorganisms impairs the reestablishment of intraradicular and periradicular health. Methods: The present investigation evaluated the expression of inflammatory mediators produced by RAW 264.7 cells in the presence of heat-killed antigens (HK) C. albicans and E. faecalis. Cultures of RAW cells were stimulated with both antigens in the presence or absence of recombinant interferon (rIFN)-g. Parameters of cell viability, production of nitric oxide (NO), as well as the synthesis of interleukin (IL)-1a, IL-6, IL-10, IL-12, monocyte chemotactic protein-1, and tumor necrosis fac- tor (TNF)-a were analyzed. Results: Results demon- strated that cell viability was especially reduced in antigens and rIFN-g–stimulated groups. Groups stimu- lated with HK C. albicans upregulated IL-10 production. Otherwise, the addition of rIFN-g to HK C. albicans upregulated TNF-a and NO production. Groups stimu- lated with HK E. faecalis upregulated TNF-a production. HK E. faecalis and rIFN-g upregulated TNF-a and NO synthesis. The production of other cytokines remained unchanged by all stimuli. Conclusions: Knowledge regarding the host mechanism of response to microor- ganisms that perpetuate endodontic infection and the periradicular lesions can contribute to optimization of endodontic therapy. The mentioned inflammatory media- tors and virulence factors involved in endodontic failure might guide lesion progression and also be targets in the development of disinfectant and immunomodulatory agents. (J Endod 2015;-:1–5) Key Words Apical periodontitis, bone resorption, Candida albicans, endodontics, Entero- coccus faecalis E ndodontic failures are caused mainly by persistence of microorganisms in the root canal system, exacerbated immune inflammatory response, and bone resorption. The yeast Candida albicans and the gram-positive bacterium Entero- coccus faecalis are examples of microorganisms capable of resisting disinfection processes in endodontic therapy (1). The immune inflammatory response to these microorganisms may culminate in harmful and persistent host periradicular damage. Pulp and periradicular immune inflammatory response to persistent infection is driven by a wide number of cells and proteins. Macrophages actively participate in this process. Macrophage activation is related to microbicidal functions, cytokine secre- tion, immune cells recruitment and microbe phagocytosis, and/or release of toxic me- tabolites. Interferon (IFN)-g is also responsible for macrophage activation even without microbial stimuli, inducing direct antimicrobial and antigen processing and also pre- sentation mechanisms (2). In this way, macrophages derived from monocytes might be activated in 2 profiles, M1 and M2, at the infection site. M1 macrophages develop anti- microbial and antitumor function, whereas M2 macrophages are related to cellular pro- liferation and tissue repair (3). Evidence suggests that the induction of bone destruction occurs after the activation of osteoclast cells (4). Osteoclast differentiation may be affected by different cytokine stimuli produced by immunocompetent cells in apical periodontitis (5). Therefore, macrophage M1 activation can be involved with interleukin (IL)-6, IL-12, and tumor necrosis factor (TNF)-a production, whereas IL-10 production is involved with M2 acti- vation (6). The present study evaluated the expression of important inflammatory me- diators in the presence of heat-killed (HK) antigens of C. albicans and E. faecalis in RAW 264.7 monocyte cells. From the *Centro de An alises Prote^ omicas e Bioqu  ımicas, Programa de P os-Graduac ¸ ~ ao em Ci^ encias Gen^ omicas e Biotecnologia, Universidade Cat olica de Bras  ılia, Bras  ılia, Distrito Federal; † Curso de Odontologia, Universidade Cat olica de Bras  ılia, Bras  ılia, Distrito Federal; ‡ Programa de P os-Graduac ¸ ~ ao em Ci^ encias da Sa ude, Uni- versidade de Bras  ılia, Bras  ılia, Distrito Federal; § Programa de P os-Graduac ¸ ~ ao da Rede Centro-Oeste, Bras  ılia, Distrito Federal; jj Curso de Educac ¸ ~ ao F  ısica, Universidade Federal de Mato Grosso do Sul - UFMS, Campo Grande, Mato Grosso do Sul; ¶ Instituto Federal de Bras  ılia, Bras  ılia, Distrito Federal; and **S-Inova, P os-Graduac ¸ ~ ao em Biotecnologia, Universidade Cat olica Dom Bosco, Campo Grande, Mato Grosso do Sul, Brazil. Address requests for reprints to Dr Taia Maria Berto Rezende, Universidade Cat olica de Bras  ılia, P os-Graduac ¸ ~ ao em Ci^ encias Gen^ omicas e Biotecnologia, SGAN 916N, Av. W5, Campus II, Modulo C, Room C-218, Bras  ılia, DF, Brazil. E-mail address: taiambr@gmail.com or taia@ucb.br 0099-2399/$ - see front matter Copyright ª 2015 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2015.02.016 Basic Research—Biology JOE — Volume -, Number -, - 2015 Cell Response to Endodontic Pathogens 1