Huashan Liu1,2,3, Zhenxing Liang1,2, Fengwei Wang4, Xiaobin Zheng1, Ziwei Zeng1, Xiaowen He1, Xiang Gao5, Min Zhi5, Xiaojian Wu1, Xianrui Wu1,2,3, Ping Lan1,2,3. 1. Department of Colorectal Surgery, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China. 2. Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China. 3. Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China. 4. State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, China. 5. Department of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
Abstract
BACKGROUND AND AIMS: Sustained activation of CD4+ T cells plays important roles in the pathogenesis of Crohn's disease (CD). Under physiologic conditions, activated T cells can be timely eliminated by a process termed activation-induced cell death (AICD), restraining T-cell over-activation and preventing immunological destruction. We inquired whether defective AICD might explain CD4+ T-cell over-activation in CD and investigated the underlying mechanisms. METHODS: CD14+ macrophages (Mφ) and CD4+ T cells were isolated from intestinal tissues or peripheral blood of controls and CD patients. An ex vivo evaluation system was employed to simulate AICD and cell apoptosis was measured by flow cytometry. RESULTS: CD4+ T cells from CD patients fail to undergo AICD in the ex vivo system. Specifically, proinflammatory type 1 helper T (Th1) and type 17 helper T (Th17) cells, rather than immunosuppressive regulatory T (Treg) cells evade AICD in CD. CD14+ Mφ in the intestinal inflammatory microenvironment of CD promote AICD resistance in CD4+ T cells via a cell-to-cell contact-independent manner. Mechanistically, CD14+ Mφ released exosomes express membrane TNF which engages TNFR2 on CD4+ T cells and triggers NF-κB signaling, thereby causing AICD resistance. Importantly, clinically applicable anti-TNF antibodies effectively blocked exosomal membrane TNF-induced CD4+ T-cell AICD resistance. CONCLUSIONS: CD14+ Mφ participate in CD pathogenesis by inducing AICD resistance through release of exosomal membrane TNF to activate the TNFR2/NF-κB pathway in CD4+ T cells. These results present new insights into CD pathogenesis and extend mechanistic understanding of anti-TNF agents.
BACKGROUND AND AIMS: Sustained activation of CD4+ T cells plays important roles in the pathogenesis of Crohn's disease (CD). Under physiologic conditions, activated T cells can be timely eliminated by a process termed activation-induced cell death (AICD), restraining T-cell over-activation and preventing immunological destruction. We inquired whether defective AICD might explain CD4+ T-cell over-activation in CD and investigated the underlying mechanisms. METHODS:CD14+ macrophages (Mφ) and CD4+ T cells were isolated from intestinal tissues or peripheral blood of controls and CD patients. An ex vivo evaluation system was employed to simulate AICD and cell apoptosis was measured by flow cytometry. RESULTS:CD4+ T cells from CD patients fail to undergo AICD in the ex vivo system. Specifically, proinflammatory type 1 helper T (Th1) and type 17 helper T (Th17) cells, rather than immunosuppressive regulatory T (Treg) cells evade AICD in CD. CD14+ Mφ in the intestinal inflammatory microenvironment of CD promote AICD resistance in CD4+ T cells via a cell-to-cell contact-independent manner. Mechanistically, CD14+ Mφ released exosomes express membrane TNF which engages TNFR2 on CD4+ T cells and triggers NF-κB signaling, thereby causing AICD resistance. Importantly, clinically applicable anti-TNF antibodies effectively blocked exosomal membrane TNF-induced CD4+ T-cell AICD resistance. CONCLUSIONS:CD14+ Mφ participate in CD pathogenesis by inducing AICD resistance through release of exosomal membrane TNF to activate the TNFR2/NF-κB pathway in CD4+ T cells. These results present new insights into CD pathogenesis and extend mechanistic understanding of anti-TNF agents.
Authors: Charles Caër; Frida Gorreja; Sophia K Forsskåhl; Siggeir F Brynjolfsson; Louis Szeponik; Maria K Magnusson; Lars G Börjesson; Mattias Block; Elinor Bexe-Lindskog; Mary Jo Wick Journal: J Crohns Colitis Date: 2021-08-02 Impact factor: 9.071