title: Silencing of fas, fas-associated via death domain, or caspase 3 differentially affects lung inflammation, apoptosis, and development of trauma-induced septic acute lung injury.
abstract: Activation of Fas signaling is a potentially important pathophysiological mechanism in the development of septic acute lung injury (ALI). However, so far the optimal targets within this signaling cascade remain elusive. Thus, we tested the hypothesis that in vivo gene silencing of Fas, Fas-associated via death domain (FADD), or caspase 3 by intratracheal administration of small interfering RNA would ameliorate ALI in a clinically relevant double-hit mouse model of trauma induced septic lung injury. Male C57Bl/6 mice received small interfering (Fas, FADD, caspase 3) or control RNA 24 h before and 12 h after blunt chest trauma or sham procedures. Polymicrobial sepsis was induced by cecal ligation and puncture 24 h after chest trauma. Twelve or 24 h later, lung tissue, plasma, and bronchoalveolar lavage fluid were harvested. During ALI, lung apoptosis (active caspase 3 Western blotting, TUNEL staining) was substantially increased when compared with sham. Silencing of caspase 3 or FADD both markedly reduced pulmonary apoptosis. Fas- and FADD-small interfering RNA administration substantially decreased lung cytokine concentration, whereas caspase 3 silencing did not reduce lung inflammation. In addition, Fas silencing markedly decreased lung neutrophil infiltration. Interestingly, only in response to caspase 3 silencing, ALI-induced lung epithelial barrier dysfunction was substantially improved, and histological appearance was beneficially affected. Taken together, downstream inhibition of lung apoptosis via caspase 3 silencing proved to be superior in mitigating ALI when compared with upstream inhibition of apoptosis via Fas or FADD silencing, even in the presence of additional anti-inflammatory effects. This indicates a major pathophysiological role of lung apoptosis and suggests the importance of other than Fas-driven apoptotic pathways in trauma-induced septic ALI.
authors.affiliation: Department of Trauma, Hand, Plastic, and Reconstructive Surgery, University of Ulm, Ulm, Germany. Mario.perl@uniklinik-ulm.de
authors.forename: Mirko Philipp
authors.initials: MP
authors.lastname: Messer
authors.forename: Philipp
authors.initials: P
authors.lastname: Kellermann
authors.forename: Sascha Jörn
authors.initials: SJ
authors.lastname: Weber
authors.forename: Christoph
authors.initials: C
authors.lastname: Hohmann
authors.forename: Stephanie
authors.initials: S
authors.lastname: Denk
authors.forename: Bettina
authors.initials: B
authors.lastname: Klohs
authors.forename: Anke
authors.initials: A
authors.lastname: Schultze
authors.forename: Sonja
authors.initials: S
authors.lastname: Braumüller
authors.forename: Markus Stefan
authors.initials: MS
authors.lastname: Huber-Lang
authors.forename: Mario
authors.initials: M
authors.lastname: Perl
mesh_terms: D055371:Acute Lung Injury / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D053148:Caspase 3 / Q000235:genetics* / Q000502:physiology; D016207:Cytokines / Q000097:blood; D004195:Disease Models, Animal; D053222:Fas Ligand Protein / Q000097:blood; D053200:Fas-Associated Death Domain Protein / Q000235:genetics* / Q000502:physiology; D020868:Gene Silencing; D015316:Genetic Therapy / Q000379:methods*; D016753:Interleukin-10 / Q000097:blood; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020556:Neutrophil Infiltration / Q000235:genetics; D011014:Pneumonia / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D014949:Wounds, Nonpenetrating / Q000235:genetics / Q000473:pathology; D019014:fas Receptor / Q000235:genetics* / Q000502:physiology
chemical_list: D016207:Cytokines; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; C505658:Fasl protein, mouse; D034741:RNA, Small Interfering; D019014:fas Receptor; D016753:Interleukin-10; D053148:Caspase 3