Pulmonary Epithelial TLR4 Activation Leads to Lung Injury in Neonatal Necrotizing Enterocolitis.
We seek to define the mechanisms leading to the development of lung disease in the setting of neonatal necrotizing enterocolitis (NEC), a life-threatening gastrointestinal disease of premature infants characterized by the sudden onset of intestinal necrosis. NEC development in mice requires activation of the LPS receptor TLR4 on the intestinal epithelium, through its effects on modulating epithelial injury and repair. Although NEC-associated lung injury is more severe than the lung injury that occurs in premature infants without NEC, the mechanisms leading to its development remain unknown. In this study, we now show that TLR4 expression in the lung gradually increases during postnatal development, and that mice and humans with NEC-associated lung inflammation express higher levels of pulmonary TLR4 than do age-matched controls. NEC in wild-type newborn mice resulted in significant pulmonary injury that was prevented by deletion of TLR4 from the pulmonary epithelium, indicating a role for pulmonary TLR4 in lung injury development. Mechanistically, intestinal epithelial TLR4 activation induced high-mobility group box 1 release from the intestine, which activated pulmonary epithelial TLR4, leading to the induction of the neutrophil recruiting CXCL5 and the influx of proinflammatory neutrophils to the lung. Strikingly, the aerosolized administration of a novel carbohydrate TLR4 inhibitor prevented CXCL5 upregulation and blocked NEC-induced lung injury in mice. These findings illustrate the critical role of pulmonary TLR4 in the development of NEC-associated lung injury, and they suggest that inhibition of this innate immune receptor in the neonatal lung may prevent this devastating complication of NEC.
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Hongpeng
H
Jia
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Chhinder P
CP
Sodhi
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Yukihiro
0000-0003-3988-2912
Y
Yamaguchi
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Peng
P
Lu
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Laura Y
LY
Martin
Division of Newborn Medicine, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, PA 15224; and.
Misty
M
Good
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Qinjie
Q
Zhou
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Jungeun
0000-0002-8184-0372
J
Sung
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
William B
WB
Fulton
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Diego F
0000-0001-7687-6920
DF
Nino
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287;
Thomas
T
Prindle
Division of Pediatric Pathology, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, Pittsburgh, PA 15224.
John A
JA
Ozolek
Division of General Pediatric Surgery, Johns Hopkins University and Bloomberg Children's Center, Johns Hopkins Hospital, Baltimore, MD 21287; Dhackam1@jhmi.edu.
David J
DJ
Hackam
D000818:Animals; D000831:Animals, Newborn; D054365:Chemokine CXCL5 / Q000378:metabolism; D020345:Enterocolitis, Necrotizing / Q000150:complications* / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D024243:HMGB1 Protein / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D055370:Lung Injury / Q000209:etiology* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D060888:Real-Time Polymerase Chain Reaction; D020545:Respiratory Mucosa / Q000276:immunology / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis*
D054365:Chemokine CXCL5; D024243:HMGB1 Protein; D051197:Toll-Like Receptor 4