Silencing of fas-associated death domain protects mice from septic lung inflammation and apoptosis.
BACKGROUND
A better understanding of the molecular mechanisms involved in the pathogenesis of sepsis and its resultant organ failure and new therapeutic approaches and targets are urgently needed. Accumulating evidence suggests that apoptosis plays an important role in the pathophysiology of sepsis and that apoptosis may be detrimental in septic acute lung injury (ALI).


OBJECTIVE
We tested the hypothesis that systemic administration of small interfering RNA (siRNA) targeting Fas-associated death domain (FADD), which recruits procaspase-8 into the death-inducing signaling complex, may be protective in septic ALI and mortality.


METHODS
Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in BALB/c mice. In vivo delivery of siRNA was performed by using a transfection reagent at 10 hours after CLP. As a negative control, animals received nonsense (scrambled) siRNA.


RESULTS
In CLP-induced septic mice, surface expression of death receptors was up-regulated, and FADD was highly expressed. DNA fragmentation ladder and transferase-mediated dUTP nick end labeling assays showed that treatment with FADD siRNA suppressed apoptosis induction in septic lungs. This siRNA treatment prevented the ALI development in CLP mice, as indicated by the findings that blood-gas derangements, histologic lung damage, and increased pulmonary inflammatory cells were greatly improved. Finally, FADD siRNA administration dramatically improved the survival of CLP mice.


CONCLUSIONS
These results indicate the pathophysiologic significance of the death receptor apoptotic pathway, including FADD, in septic ALI and the potential usefulness of FADD siRNA for gene therapy of the septic syndrome.
Matsuda
Naoyuki
N
Department of Molecular and Medical Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
Yamamoto
Seiji
S
Takano
Ken-Ichi
K
Kageyama
Shun-Ichiro
S
Kurobe
Yusuke
Y
Yoshihara
Yasunori
Y
Takano
Yasuo
Y
Hattori
Yuichi
Y
D055371:Acute Lung Injury / Q000473:pathology*; D000818:Animals; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism; D053200:Fas-Associated Death Domain Protein / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing; D006863:Hydrogen-Ion Concentration; D020287:In Situ Nick-End Labeling; D008168:Lung / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D034741:RNA, Small Interfering / Q000008:administration & dosage; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D018805:Sepsis / Q000473:pathology*; D013154:Spleen / Q000473:pathology; D053199:TNF Receptor-Associated Death Domain Protein / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
D053200:Fas-Associated Death Domain Protein; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053199:TNF Receptor-Associated Death Domain Protein; C481226:Tradd protein, mouse; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D053181:Caspase 8