A novel Fas-binding outer membrane protein and lipopolysaccharide of Leptospira interrogans induce macrophage apoptosis through the Fas/FasL-caspase-8/-3 pathway
Authors: Ai-Hua Sun
Jie Yan
Shi-Jun Li
Wei-Lin Hu
David M Ojcius
Peng Du
Xu&#x27;ai Lin
Kai-Xuan Li
Journal: Emerging Microbes & Infections (2018)
Discipline: MICROBIOLOGY
Keywords: Leptospira interrogans; leptospirosis; zoonotic infectious disease; macrophage apoptosis; Lep-OMP047
Affiliations: Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310003, People's Republic of China., Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, People's Republic of China., Faculty of Basic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang, 310053, People's Republic of China., Institute of Communicable Disease Prevention and Control, Guizhou Provincial Centre for Disease Control and Prevention, Guiyang, Guizhou, 550004, People's Republic of China., Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, 155 Fifth Street, San Francisco, CA, 94103, USA., Division of Basic Medical Microbiology, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310003, People's Republic of China. ., Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, People's Republic of China. ., Faculty of Basic Medicine, Hangzhou Medical College, Hangzhou, Zhejiang, 310053, People's Republic of China. ., Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang, 310003, People's Republic of China. .

Abstract:  Leptospira interrogans is the major causative agent of leptospirosis, an emerging, globally spreading zoonotic infectious disease. The pathogen induces macrophage apoptosis, but the molecular basis and mechanism remain unknown. In the present study, we found that L. interrogans caused apoptosis of phagocytosis-inhibited macrophages, and the product of the L. interrogans LB047 gene (Lep-OMP047) was the unique protein captured by mouse and human Fas proteins. The recombinant expressed Lep-OMP047 (rLep-OMP047) strongly bound mouse and human Fas proteins with equilibrium association constant (KD) values of 5.20 × 10-6 to 2.84 × 10-9 M according to surface plasmon resonance measurement and isothermal titration calorimetry. Flow-cytometric examination showed that 5 μg rLep-OMP047 or 1 μg lipopolysaccharide of L. interrogans (Lep-LPS) caused 43.70% or 21.90% early apoptosis in mouse J774A.1 macrophages and 28.41% or 15.80% for PMA-differentiated human THP-1 macrophages, respectively, but the apoptosis was blocked by Fas-antagonizing IgGs, Fas siRNAs, and caspase-8/-3 inhibitors. Moreover, Lep-OMP047 was significantly upregulated during infection of macrophages. Lep-LPS promoted the expression and cytomembrane translocation of Fas and FasL in macrophages. The JNK and p38 MAPK but not ERK signaling pathways, as well as the transcription factors c-Jun and ATF2 but not CHOP, mediated Lep-LPS-induced Fas/FasL expression and translocation. TLR2 but not TLR4 mediated Lep-LPS-induced JNK/p38 MAPK activation. Therefore, we demonstrated that a novel Fas-binding OMP and LPS of L. interrogans induce macrophage apoptosis through the Fas/FasL-caspase-8/-3 pathway. 

Retracted: No

PubPeer comments:
 Figure 1C. * Red boxes: Two panels appear to look unexpectedly similar. ![file] , 
 Figure 2A. * Blue boxes: Two panels appear to look unexpectedly similar. ![file] , 
 Figure 2C. * Teal boxes: two areas in the same panel appear to look very similar * Pink boxes: four areas in three panels appear to look very similar * Green boxes: two areas in two panels appear to look very similar * Burgundy boxes: two areas in the same panel appear to look very similar * Orange boxes: two areas in the same panel appear to look very similar ![file] (Updated with findings through social media). , 
 Dear Pubpeer, We thank the readers for identifying problems with the data. We are very sorry that the manuscript had these issues. I am contacting the other co-authors and we will also inform the journal. Jie Yan , 
 2A. Two panels share some identical features. ![file] , 
 Correction, April 2021, found here: https: www.tandfonline.com doi full 10.1080 22221751.2021.1918844  When this article was first published on 31 July 2018, Figure 2A contained identical panels. The authors confirmed that panel u201cTHP-1 100 u03bcg: Before treatmentu201d was an accidental duplication of u201cJ774A.1-200 u03bcg: Before treatment.u201d The figure has been updated with the corrected panel. The authors apologize for any inconvenience caused by this error. Of note, this correction does not address the duplicated panels in Figure 1C and 2C. It also does not address the duplicated part of panels, which seem very hard to explain by a technical error or unintentional mistake. Can the authors and journal please clarify how these type III duplications should be addressed? ,