Behavioral changes in response to feeding pancreatic-like enzymes to exocrine pancreatic insufficiency pigs

Pancreatic-like enzymes of microbial origin restore growth and normalize lipid absorption in a pig model with exocrine pancreatic insufficiency

INTRODUCTION

The standard therapy for exocrine pancreatic insufficiency (EPI) is porcine-derived pancreatic enzyme replacement therapy (PERT). In the present study we tested a new approach with a mixture of pancreatic-like enzymes of microbial origin (PLEM) in a 1-week efficacy study in EPI pigs. In addition to the conventionally used coefficient of fat and nitrogen absorption (CFA and CNA), parameters that more accurately reflect the nutritional and health status, such as changes in the lipemic index (LI), plasma triglyceride (TG) and non-esterified fatty acid (NEFA) levels, and somatic growth, were determined.

MATERIAL AND METHODS

A PLEM dose containing 120 000 active lipase units, 80 000 active protease units and 12 000 active amylase units (all from Sigma, St. Louis, MO) was given as a powder, twice daily with a meal (40 g fat/meal) to 8 EPI pigs for 7 days. Ten healthy pigs were used as a comparator.

RESULTS

The PLEM enhanced fat and protein digestion, and reversed growth impairment in EPI pigs. With treatment, CFA and CNA increased by 59% and 43% (p < 0.05), respectively. Although fat and protein absorption were lower than in the comparator, the postprandial blood lipid profile was normal as in healthy pigs. The mucosal thickness significantly increased by 27%, 50% and 26%, in the proximal, middle, and distal jejunum (p < 0.05) with treatment and resembled that of healthy animals.

CONCLUSIONS

Pancreatic-like enzymes of microbial origin supported somatic growth and normalized the postprandial lipid profile. As a measure of efficacy, postprandial LI, TG and NEFA are viable endpoints to be explored in human trials.

Experiments suggesting extra-digestive effects of enteral pancreatic amylase and its peptides on glucose homeostasis in a pig model

The studies presented were designed to highlight the impact of pancreatic enzymes on glycemic control and insulin response. Blood glucose and plasma insulin levels were monitored after intravenous, oral or direct gut glucose tolerance tests (GTT) in 6 pigs with an intact gastrointestinal tract and in 12 pigs following duodenal-jejunal bypass (DJB) surgery. In the intact pigs, pancreatic enzymes (Creon®) given orally 1 h prior to the GTT, lowered the blood glucose levels during the oral and meal GTT and reduced the plasma insulin response during the intravenous and meal GTT. In DJB pigs, blood glucose and plasma insulin levels were higher following glucose loading into the by-passed biliopancreatic limb as compared to that following glucose loading orally or into the common intestinal limb. Infusion of amylase or amylase peptides together with glucose into the biliopancreatic limb lowered blood glucose levels in DJB pigs. These preliminary data suggest new, extra-digestive, actions of enteral pancreatic enzymes – probably amylase or its peptides – on glucose homeostasis, with an reduction in net glucose absorption into the blood and in insulin response. This ability of digestive enzymes (amylase) to reduce post-prandial hyperglycaemia in an insulin-independent manner could aid in preventing the development of obesity and diabetes.

The Pancreatic Duct Ligated (Mini)pig as a Model for Pancreatic Exocrine Insufficiency in Man

Modern therapy of pancreatic exocrine insufficiency (PEI) using pancreatic enzyme replacement therapy (PERT) has largely been very effective and has greatly helped in improving the nutritional status of patients with PEI and in increasing the life expectancy in cystic fibrosis. It is believed that the use of predictable large animal models could play an important role in assessing and developing new therapies. This article reviews the pancreatic duct ligated (adult) minipig as a chronic model of total PEI, with a detailed look at the influence of PEI and response to PERT on prececal compared to fecal digestibility, to directly investigate effects on protein and starch digestion and absorption. In addition, the piglet with PEI is reviewed as a model for PEI in young patients with the aim of further improving the therapy and nutritional status of young patients with cystic fibrosis.

Partial optimization of the 5-terminal codon increased a recombination porcine pancreatic lipase (opPPL) expression in Pichia pastoris

Pancreatic lipase plays a key role in intestinal digestion of feed fat, and is often deficient in young animals such as weaning piglets. The objective of this study was to express and characterize a partial codon optimized porcine pancreatic lipase (opPPL). A 537 bp cDNA fragment encoding N-terminus amino acid residue of the mature porcine pancreatic lipase was synthesized according to the codon bias of Pichia pastoris and ligated to the full-length porcine pancreatic lipase cDNA fragment. The codon optimized PPL was cloned into the pPICZαA (Invitrogen, Beijing, China) vector. After the resultant opPPL/pPICZαΑ plasmid was transformed into P.pastoris, the over-expressed extracellular opPPL containing a His-tag to the C terminus was purified using Ni Sepharose affinity column (GE Healthcare, Piscataway, NJ, USA), and was characterized against the native enzyme (commercial PPL from porcine pancreas, Sigma). The opPPL exhibited a molecular mass of approximately 52 kDa, and showed optimal temperature (40°C), optimal pH (8.0), K_m (0.041 mM), and V_max (2.008 µmol.mg protein ⁻¹.min⁻¹) similar to those of the commercial enzyme with p-NPP as the substrate. The recombinant enzyme was stable at 60°C, but lost 80% (P<0.05) of its activity after exposure to heat ≥60°C for 20 min. The codon optimization increased opPPL yield for ca 4 folds (146 mg.L⁻¹ vs 36 mg.L⁻¹) and total enzyme activity increased about 5 folds (1900 IU.L⁻¹ vs 367 IU.L⁻¹) compared with those native naPPL/pPICZαΑ tranformant. Comparison of gene copies and mRNA profiles between the two strains indicated the increased rePPL yields may partly be ascribed to the increased protein translational efficiency after codon optimization. In conclusion, we successfully optimized 5-terminal of porcine pancreatic lipase encoding gene and over-expressed the gene in P. pastoris as an extracellular, functional enzyme. The recombination enzyme demonstrates a potential for future use as an animal feed additive for animal improvement.