Candida albicans infection mediates gastrointestinal track malignancy independently of Il17a in an APECED mouse model.

The cytokine Il17a plays an important role in protection against fungal infection, yet it also serves as a pathogenic factor in several inflammation-related cancers. Previously we reported that fungal infection promotes the development of esophageal squamous cell carcinoma (ESCC) in the IKKalpha kinase-dead KA knock-in (KA) mice that mimic a human autoimmune disorder, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Our data showed that KA T cells failed to induce Il17a in response to fungal infection. However, the role of Il17a in fungal infection-mediated esophageal carcinogenesis remains to be further determined. In this study, we crossed KA mice with Il17a-/- mice to generate KA;Il17a-/- double mutant mice. We orally inoculated WT, Il17a-/-, KA, and KA;Il17a-/- mice with Candida albicans weekly for 3 months to investigate gastrointestinal (GI) track tumorigenesis, including the SCC development in the oral cavity, esophagus, and forestomach. We found that loss of Il17a leads to much earlier onset of GI track tumors in KA;Il17a-/- mice than that in KA mice. KA;Il17a-/- mice also died much earlier compared to KA mice, which is likely due to increased C. albicans burden in the absence of Il17a. The incidence of GI track tumors is comparable between KA and KA;Il17a-/- mice, suggesting that C. albicans infection-associated GI track tumorigenesis is independent of Il17a in KA mouse model. To further understand the underlying mechanism, we performed single-cell RNA sequencing analysis for CD45+ immune cells isolated from long-term C. alibicans-infected mouse esophagi of WT, Il17a-/-, KA, and KA;Il17a-/- mouse cohorts. Interestingly, the neutrophil population was significantly increased in the esophagi of KA and KA;Il17a-/- mice compared to WT and Il17a-/- mice. However, KA neutrophils exhibited reduced capacity in killing C. albicans with reduced NETs formation compared to WT neutrophils, suggesting that the defect in NETs formation may play a pivotal role in GI track tumorigenesis in the context of fungal infection. We are currently investigating how the interplay between C. albicans infection and host neutrophils regulates Candida infection-associated GI track tumorigenesis. This abstract is also being presented as Poster B01. Citation Format: Feng Zhu, Jami Willette-Brown, Trang Phan, Yongmei Zhao, Bao Tran, Scott G. Filler, Mihalis S. Lionakis, Yinling Hu. Candida albicans infection mediates gastrointestinal track malignancy independently of Il17a in an APECED mouse model [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr PR10.