Abstract A70: Colorectal carcinogenesis is precluded by intestinal Treg cell accumulation in post-sepsis state
Authors: Leite Caio Abner Vitorino Goncalves , Mota Jose Mauricio Segundo Correia , Lima Kalil Alves , Nascimento Leticia Almeida , Ferreira Marcela Davoli , Viacava Paula Ramos , Begnami Maria Dirlei , Filho Jose Carlos Alves , Lima Roberto Cesar Pereira , Lima Vladmir Claudio Cordeiro , Cunha Fernando Queiroz 
Published: May 2019

Introduction: Inflammation influences colorectal carcinogenesis and patients with inflammatory bowel disease are more prone to develop colorectal cancer (CRC). Varipous evidence points towards sepsis-surviving individuals experiencing a prolonged state of immunosuppression. The aim of this study was to evaluate if colitis-induced CRC initiation and progression was affected in sepsis-surviving mice.

Experimental Procedures: C57Bl6 mice were submitted to cecal ligation and puncture (CLP) model, and after 15 days, sepsis-surviving mice and one control group received azoxymethane (AOM, 10 mg/kg, ip) and dextran sodium sulfate (DSS 2%, ad libitum, 3 cycles of 5 days) on days 20-25, 40-45, and 60-65 post-CLP. Colitis and tumor development were evaluated by serial colonoscopies. Cytokines (IFN-γ, IL-1β, TNF, IL-6, IL-17, TGF), chemokines (KC and MIG), and GM-CSF were quantified on days 0, 12, 52, and 65 by Milliplex and Treg cells on days 12 and 65 by flow cytometry. Two groups of C57 animals received cyclophosphamide (CYP) (100 mg/kg, ip), and two groups of animals expressing diphtheria toxin (DTX) receptor under-regulation of Foxp3 received DTX (0.5 mg/animal, ip) before the AOM/DSS protocol. Another animal cohort was submitted to CLP after receiving AOM/DSS, and two other groups were injected with murine CRC cells (MC38luc) 105 cells s.c. or 106 cells intra-splenically 15 days post-CLP.

Results: Sepsis-surviving animals showed reduced colitis and lower incidence, number of tumors, and tumor load than control animals. Lower levels of IFN-γ in the colon on day 12, and of IL-1β, TNF, IL-6, IL-17, KC, and MIG on days 12 and 65, in addition to IL-33, TG,F and GM-CSF on day 65, were detected in sepsis-surviving mice. Tregs accumulated in a more pronounced fashion in sepsis-surviving mice on D15. Treg depletion through CYP or DTX restored colitis and CRC incidence in post-sepsis mice. Conversely, mice submitted to sepsis after AOM/DSS showed an increase in tumor load 30 days after CLP when compared to controls. Furthermore, in the subcutaneous and intrasplenic colorectal cancer model, increased tumor growth was observed in post-sepsis animals when compared to the controls.

Conclusion: Colitis-dependent CRC carcinogenesis was reduced by post-sepsis state in mice in a Treg-dependent manner.

Citation Format: Caio Abner Vitorino Goncalves Leite, Jose Mauricio Segundo Correia Mota, Kalil Alves Lima, Leticia Almeida Nascimento, Marcela Davoli Ferreira, Paula Ramos Viacava, Maria Dirlei Begnami, Jose Carlos Alves Filho, Roberto Cesar Pereira Lima Jr., Vladmir Claudio Cordeiro Lima, Fernando Queiroz Cunha. Colorectal carcinogenesis is precluded by intestinal Treg cell accumulation in post-sepsis state [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A70.