P145 HCQ alleviates 5-FU-induced intestinal inflammation through inhibiting TLR9-dependent DNA sensing pathway
Authors: X Li, Y Sun, J Zhang, J He, C Yu, H Jie, E Sun
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Career situation of first and presenting author</h3> Young investigator. <h3>Introduction</h3> Evidences revealed that chemotherapies could trigger DNA release, then induce inflammation of intestinal tissues which damp the effect of anti-cancer treatment.<sup>1 2</sup> DNA released induces the translocation of TLR9 to endolysosomes and subsequent nuclear factor-κB (NF-κB) activation, which leads to interleukin-1β (IL-1β) secretion and inflammation.<sup>3</sup> Targeting TLR9-dependent DNA sensing pathway may be a valuable therapy for chemotherapy induced intestinal mucositis. <h3>Objectives</h3> This study aims to investigate whether hydroxychloroquine (HCQ), suppresses 5-FU-induced intestinal mucositis through inhibiting TLR9-dependent DNA sensing pathway. <h3>Methods</h3> The effect of HCQ on 5-FU-induced intestinal mucositis were examined<i> in vivo</i> and<i> in vitro</i>. We established 5-FU-induced intestinal mucositis model and assessed body weight, diarrhea score and histopathologic changes following HCQ treatment <i>in vivo</i>, then TLR9 and NF-κB expression of small intestine and IL-1β secretion of serum were analyzed. Bone marrow-derived macrophages (BMDMs) were cultured, transfected with calf-thymus DNA(CT-DNA) and treated with HCQ for 6 hour <i>in vitro</i>. TLR9 and NF-κB expression and IL-1β secretion in BMDMs were then investigated. <h3>Results</h3> HCQ treatment markedly attenuated body weight loss, severity of diarrhea, intestine shortening, and destruction of small intestinal in histopathology of 5-FU- treated mice <i>in vivo</i>. Also HCQ treatment inhibited TLR9 and NF-κB expression in small intestine of 5-FU- treated mice and pro-inflammatory IL-1β secretion in serum of 5-FU- treated mice. Meanwhile administration of HCQ reduced the number of macrophages in small intestine of 5-FU-treated mice. Then BMDMs were cultured, transfected with CT-DNA and treated with HCQ <i>in vitro</i>. We found HCQ efficiently inhibited TLR9 expression, translocation of NF-κB to nucleus, and IL-1β secretion in supernatant of CT-DNA stimulated BMDMs. <h3>Conclusions</h3> These results provides a new insight into the mechanism of chemotherapy induced intestinal mucositis and indicate HCQ may be used as a strategy against intestinal mucositis during 5-FU chemotherapy. <h3>References</h3> Woo S-R, Fuertes MB, Corrales L, <i>et al</i>. STING-Dependent Cytosolic DNA Sensing Mediates Innate Immune Recognition of Immunogenic Tumors. <i>Immunity</i> 2014;41:830–42. Hu B, Jin C, Li H-B, <i>et al</i>. The DNA Sensing Aim2 Inflammasome Controls Radiation Induced Cell death and Tissue Injury. <i>Science (New York, NY)</i>. 2016;354:765–8. Miura K, Kodama Y, Inokuchi S, <i>et al</i>. Toll-Like Receptor 9 Promotes Steatohepatitis by Induction of Interleukin-1β in Mice. <i>Gastroenterology</i>. 2010;139:323–34.e7. <h3>Acknowledgements</h3> The authors confirm that there are no conflicts of interest. <h3>Disclosure of Interest</h3> None declared.