Helminth infection impairs autophagy-mediated killing of bacterial enteropathogens by macrophages.
Autophagy is an important mechanism used by macrophages to kill intracellular pathogens. The results reported in this study demonstrate that autophagy is also involved in the macrophage killing of the extracellular enteropathogen Citrobacter rodentium after phagocytosis. The process was significantly impaired in macrophages isolated from mice chronically infected with the helminth parasite Heligmosomoides polygyrus. The H. polygyrus-mediated inhibition of autophagy was Th2 dependent because it was not observed in macrophages isolated from helminth-infected STAT6-deficient mice. Moreover, autophagy of Citrobacter was inhibited by treating macrophages with IL-4 and IL-13. The effect of H. polygyrus on autophagy was associated with decreased expression and processing of L chain protein 3 (LC3), a key component of the autophagic machinery. The helminth-induced inhibition of LC3 expression and processing was STAT6 dependent and could be recapitulated by treatment of macrophages with IL-4 and IL-13. Knockdown of LC3 significantly inhibited autophagic killing of Citrobacter, attesting to the functional importance of the H. polygyrus-mediated downregulation of this process. These observations reveal a new aspect of the immunosuppressive effects of helminth infection and provide mechanistic insights into our earlier finding that H. polygyrus significantly worsens the in vivo course of Citrobacter infection.
Mucosal Immunology Laboratory, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
Chien-wen
CW
Su
Yue
Y
Cao
Mei
M
Zhang
Jess
J
Kaplan
Libo
L
Su
Ying
Y
Fu
W Allan
WA
Walker
Ramnik
R
Xavier
Bobby J
BJ
Cherayil
Hai Ning
HN
Shi
D000818:Animals; D001343:Autophagy / Q000276:immunology*; D044082:Citrobacter rodentium / Q000254:growth & development / Q000276:immunology* / Q000472:pathogenicity; D015536:Down-Regulation / Q000276:immunology; D004756:Enterobacteriaceae Infections / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D005260:Female; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D009351:Nematospiroides dubius / Q000254:growth & development / Q000276:immunology* / Q000472:pathogenicity; D011499:Protein Processing, Post-Translational / Q000276:immunology; D017206:Strongylida Infections / Q000276:immunology* / Q000382:microbiology / Q000473:pathology
C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins