Epithelial cells of female genital tract mount a Type I Interferon response against Candida albicans

RODRIGUEZ, EMILSE; MIRÓ, MARÍA SOLEDAD; VIGEZZI, CECILIA; ICELY, PAULA ALEJANDRA; MACCIONI, MARIANA; RIERA, FERNANDO OSCAR; CAEIRO, JUAN PABLO; SOTOMAYOR, CLAUDIA ELENA

Curitiba

Congreso; 15th INFOCUS; 2017

Introduction: Type I interferons (IFNs-I) constitute a family of pleiotropic cytokines that play a crucial role during infection by coordinating the function of different immunocompetent cells involved in the induction of defense against viruses and intracellular bacteria. However, recent studies have revealed that IFNs-I can also be produced in response to fungal pathogens, but their roles in antifungal immunity have not been thoroughly investigated. Candida albicans (Ca) is the most common human fungal pathogen causing both mucosal and systemic infections. Vulvovaginal candidiasis (VVC) is an acute inflammatory disease that affects 75% of women in reproductive age at least once in their lives. Nowadays, little is known about the ability of C. albicans to induce IFNs-I in female genital tract cells and the role of these cytokines during VVC.Objective: We aimed to study whether C. albicans recognition can activate IFNs-I pathway in epithelial cells of female genital tract in order to establish a possible role during VVC.Methods: Human cervical epithelial cell line (HeLa) was stimulated with C. albicans SC5314 strain in three different conditions: Viable Infective (Ca) (fungus:cell ratio 0.25:1,0.5:1,1:1,5:1), viable Ca pseudomicelio (Amphotericin B-treated) (Ca pseudom)(5:1) and Ca DNA (complexed with polyethylenimine)(Ca DNA), during 4 and 24h. LPS and Poly I:C were used as activation controls. The expression of type IFNs-I pathway genes (IFN, IRF3, IRF7 and Mx1) was measured by qPCR and cytokine profile (IL1, IL6, TNF and TGF) by ELISA. Unstimulated cells were used as control.Results: We first evaluated the capacity of HeLa cells to express IFN mRNA in response to different stimuli. As expected, Poly I:C was able to induce a strong IFNmRNA expression at 24h, while LPS showed a significant increase at 4h (p<0.001). Interestingly, both Ca (0.25:1) and Ca pseudo (5:1) were able to induce an upregulated IFN expression on epithelial cells at 4h (p<0.01) but only Ca pseudom induced high levels of this cytokine at 24h (p<0.05). Surprisingly, Ca DNA delivered into the cytoplasm of HeLa cells also induced higher IFN mRNA levels when compared with unstimulated cells at 24h (p<0.05). Both viable Ca stimuli and activation controls induced high Mx1 expression (a post-IFN Receptor gene). However, Mx1 levels were significantly higher at 24h compared to those observed at 4h (p<0,01). IRF3 and IRF7 expression was variable among the different stimuli. Moreover, Ca, Ca DNA and Poly I:C induced high IL6 levels (p<0,001) while TNF and TGFamounts were variable among the different stimuli, and IL1 remained undetectable.Conclusion: Our results provide novel and important evidence about the ability of different components of C. albicans to activate IFNs-I pathway in epithelial cells of female genital tract, highlighting the importance of IFNs-I in modulating the cytokine profile induced in response to the invasion of this fungal pathogen. These findings further expand the spectrum of immune mediators involved in the local response during VVC.