Cholecystokinin Receptor Antagonist Therapy Decreases Inflammation and Fibrosis in Chronic Pancreatitis

Abstract

Background and aims: Chronic pancreatitis is associated with recurrent inflammation, pain, fibrosis, and loss of exocrine and endocrine pancreatic function and risk of cancer. We hypothesized that activation of the CCK receptor contributes to pancreatitis and blockade of this pathway would improve chronic pancreatitis.

Methods: Two murine models were used to determine whether CCK receptor blockade with proglumide could prevent and reverse histologic and biochemical features of chronic pancreatitis: the 6-week repetitive chronic cerulein injection model and the modified 75% choline-deficient ethionine (CDE) diet. In the CDE-fed model, half the mice received water supplemented with proglumide, for 18 weeks. After chronic pancreatitis was established in the cerulein model, half the mice were treated with proglumide and half with water. Histology was scored in a blinded fashion for inflammation, fibrosis and acinar ductal metaplasia (ADM) and serum lipase levels were measured. RNA was extracted and examined for differentially expressed fibrosis genes.

Results: Proglumide therapy decreased pancreatic weight in the CDE diet study and the cerulein-induced chronic pancreatitis model. Fibrosis, inflammation, and ADM scores were significantly reduced in both models. Lipase values improved with proglumide but not in controls in both models. Proglumide decreased pancreas mRNA expression of amylase, collagen-4, and TGFβR2 gene expression by 44, 38, and 25%, respectively, compared to control mice.

Conclusion: New strategies are needed to decreased inflammation and reduce fibrosis in chronic pancreatitis. CCK receptor antagonist therapy may improve chronic pancreatitis by reversing fibrosis and inflammation. The decrease in ADM may reduce the risk of the development of pancreatic cancer.

Keywords: CCK; Cerulein; Cholecystokinin; Pancreatitis.

Conflict of interest statement

Conflict of interest The authors declare that they have no conflict of interest.

Figures

Fig. 1

Mouse pancreatic weight mg/g of body weight. a Cerulein-treated mice show slightly less pancreatic weight after 1 week of proglumide, (p = 0.07) compared to water-treated mice. b CDE-fed mice that concomitantly received proglumide for 18 weeks had significantly less pancreatic weights (p = 0.0062). There was no difference in the pancreatic weight of mice that were on the CDE diet for 12 weeks before receiving proglumide for 6 weeks of the 18-week study

Fig. 2

a Serum lipase levels in the cerulein chronic pancreatitis were decreased in mice treated with proglumide after 1 week. b In the CDE-fed mice, serum lipase levels were significantly lower with proglumide therapy in both the prevention and recovery study compared to CDE-fed mice treated with regular water, *p < 0.05

Fig. 3

Histology scores of pancreas mean ± SD in cerulein study. a Edema scores did not significantly decrease with proglumide. b Acinar ductal metaplasia (ADM) scores decreased in the cerulein recovery phase and were less after 2 weeks with proglumide compared to control water-treated mice. *p = 0.013; **p = 0.0009; ***p = 0.0002. c Histologic inflammation scores only improved 2 weeks after withdrawing cerulein and were less in proglumide-treated mice. *p < 0.0001

Fig. 4

Masson’s trichrome staining of various cerulein-treated of mice a Baseline pancreas histology after 6 weeks of induction of chronic pancreatitis with cerulein. b Pancreas from water-treated control group 2 weeks post-cerulein therapy. c Proglumide-treated group 2 weeks post-induction of chronic pancreatitis. d Quantitative morphometry analysis shows significantly decreased fibrosis scores after 2 weeks of proglumide therapy (p = 0.0293)

Fig. 5

Alpha–SMA staining of pancreas tissues from various groups of cerulein-treated mice a. Baseline αSMA staining after 6 weeks of induction of chronic pancreatitis. b αSMA immunoreactivity in pancreas of mice treated with water 2 weeks post-induction of chronic pancreatitis. c αSMA immunoreactivity in pancreas of mice treated with proglumide 2 weeks post-induction. d Mean fibrosis scores ± SD shows only significant reduction in fibrosis after 2 weeks of proglumide therapy, p = 0.045

Fig. 6

Differentially expressed genes for fibrosis from CDE-fed mice. a Amylase mRNA expression decreased by 44% in CDE-fed mice that received proglumide compared to those that had untreated water. b Collagen-4 gene expression was decreased by 38% in CDE-fed mice that received proglumide. c TGFβR2 gene expression was decreased by 25% in CDE-fed proglumide-treated mice compared to water-treated controls