C/EBP homologous protein deficiency aggravates acute pancreatitis and associated lung injury.
OBJECTIVE
To investigate the pathophysiological role of C/EBP homologous protein (CHOP) in severe acute pancreatitis and associated lung injury.


METHODS
A severe acute pancreatitis model was induced with 6 injections of cerulein (Cn, 50 μg/kg) at 1-h intervals, then intraperitoneal injection of lipopolysaccharide (LPS, 7.5 mg/kg) in CHOP-deficient (Chop(-/-)) mice and wild-type (WT) mice. Animals were sacrificed under anesthesia, 3 h or 18 h after LPS injection. Serum amylase, lipase, and cytokines [interleukin (IL)-6 and tumor necrosis factor (TNF)-α], pathological changes, acute lung injury, and apoptosis in the pancreas were evaluated. Serum amylase and lipase activities were detected using a medical automatic chemical analyzer. Enzyme-linked immunosorbent assay kits were used to evaluate TNF-α and IL-6 levels in mouse serum and lung tissue homogenates. Apoptotic cells in sections of pancreatic tissues were determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) analysis. The mouse carotid arteries were cannulated and arterial blood samples were collected for PaO2 analysis. The oxygenation index was expressed as PaO2/FiO2.


RESULTS
Administration of Cn and LPS for 9 and 24 h induced severe acute pancreatitis in Chop(-/-) and WT mice. When comparing Chop(-/-) mice and WT mice, we observed that CHOP-deficient mice had greater increases in serum TNF-α (214.40 ± 19.52 pg/mL vs 150.40 ± 16.70 pg/mL; P = 0.037), amylase (4236.40 ± 646.32 U/L vs 2535.30 ± 81.83 U/L; P = 0.041), lipase (1678.20 ± 170.57 U/L vs 1046.21 ± 35.37 U/L; P = 0.008), and IL-6 (2054.44 ± 293.81 pg/mL vs 1316.10 ± 108.74 pg/mL; P = 0.046) than WT mice. The histopathological changes in the pancreases and lungs, decreased PaO2/FiO2 ratio, and increased TNF-α and IL-6 levels in the lungs were greater in Chop(-/-) mice than in WT mice (pancreas: Chop(-/-) vs WT mice, hemorrhage, P = 0.005; edema, P = 0.005; inflammatory cells infiltration, P = 0.005; total scores, P = 0.006; lung: hemorrhage, P = 0.017; edema, P = 0.017; congestion, P = 0.017; neutrophil infiltration, P = 0.005, total scores, P = 0.001; PaO2/FiO2 ratio: 393 ± 17.65 vs 453.8, P = 0.041; TNF-α: P = 0.043; IL-6, P = 0.040). Results from TUNEL analysis indicated increased acinar cell apoptosis in mice following the induction of acute pancreatitis. However, Chop(-/-) mice displayed significantly reduced pancreatic apoptosis compared with the WT mice (201.50 ± 31.43 vs 367.00 ± 47.88, P = 0.016).


CONCLUSIONS
These results suggest that CHOP can exert protective effects against acute pancreatitis and limit the spread of inflammatory damage to the lungs.
Te-I Weng, Hsiao-Yi Wu, Department of Forensic Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
Te-I
TI
Weng
Hsiao-Yi
HY
Wu
Bo-Lin
BL
Chen
Jie-Yang
JY
Jhuang
Kuo-How
KH
Huang
Chih-Kang
CK
Chiang
Shing-Hwa
SH
Liu
D000208:Acute Disease; D055371:Acute Lung Injury / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000681:Amylases / Q000097:blood; D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000097:blood; D002108:Ceruletide; D004195:Disease Models, Animal; D018836:Inflammation Mediators / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008049:Lipase / Q000097:blood; D008070:Lipopolysaccharides; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010179:Pancreas / Q000378:metabolism / Q000473:pathology; D010195:Pancreatitis / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012720:Severity of Illness Index; D051742:Transcription Factor CHOP / Q000172:deficiency* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D015415:Biomarkers; C497250:Ddit3 protein, mouse; D018836:Inflammation Mediators; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; C440499:lipopolysaccharide, Escherichia coli O111 B4; D051742:Transcription Factor CHOP; D002108:Ceruletide; D008049:Lipase; D000681:Amylases
Acute pancreatitis, Lung injury; Apoptosis; C/EBP homologous protein; Cytokines