TNF receptor I mediates chemokine production and neutrophil accumulation in the lung following systemic lipopolysaccharide.
BACKGROUND
Tumor necrosis factor (TNF)-alpha is a critical effector of lipopolysaccharide (LPS)-induced acute lung injury, and its effects are mediated by two structurally related receptors, RI and RII. Cellular adhesion molecules and C-X-C chemokines (Keratinocyte chemoattractant (KC) and macrophage inflammatory protein [MIP]-2) regulate tissue neutrophil polymorphonuclear neutrophil (PMN) accumulation in a multitude of inflammatory states. We hypothesized that TNFRI signaling dictates PMN accumulation in the lung via regulation of chemokine molecule production. Therefore, the purposes of this study were to (1) delineate LPS-induced lung TNF-alpha production and (2) characterize the contribution of both TNF receptors to lung chemokine production and neutrophil influx following systemic LPS.


METHODS
Wild-type or TNFRI and TNFRII knockout (KO) mice were injected with vehicle (saline) or LPS (Escherichia coli 0.5 mg/kg intraperitoneally). After 2, 4, 6, or 24 h, lungs were analyzed for TNF-alpha and chemokine (KC and MIP-2) protein expression (enzyme-linked immunosorbent assay) and PMN accumulation (myeloperoxidase assay).


RESULTS
There was an increase in total lung TNF-alpha (vehicle, 5.0 +/- 1.2 pg/mg total protein vs LPS, 950 +/- 318; P < 0.05) after LPS. Lung chemokine production and PMN accumulation were also increased compared to vehicle-injected mice. Lung chemokine production and PMN accumulation were significantly lower in TNFRI KO, but not TNFRII KO, mice, despite no difference in TNF-alpha production (TNFRI KO, 925 +/- 301 vs TNFRII KO, 837 +/- 267, P = 0.82).


CONCLUSIONS
Acute lung injury following systemic LPS administration is characterized by increased lung (1) TNF-alpha production, (2) C-X-C chemokine production, and (3) neutrophil accumulation. The maximal effect of LPS-induced lung neutrophil accumulation appears to be dependent upon the TNFRI receptor but not the TNFRII receptor. .
Calkins
C M
CM
Department of Surgery, University of Colorado Health Sciences Center and the Veterans Affairs Hospital, Denver 80262, USA. casey.calkins@uchsc.edu
Heimbach
J K
JK
Bensard
D D
DD
Song
Y
Y
Raeburn
C D
CD
Meng
X
X
McIntyre
R C
RC
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects; D018925:Chemokines / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D009504:Neutrophils / Q000502:physiology*; D018124:Receptors, Tumor Necrosis Factor / Q000502:physiology*; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D015703:Antigens, CD; D018925:Chemokines; D008070:Lipopolysaccharides; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha