|El Balaa, Mohamad|
Submitted to: Pancreas
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2003
Publication Date: 3/1/2004
Citation: Holowachuk, S.A., El Balaa, M.F., Gerard, P.D., Buddington, R.K. 2004. Nonparallel secretion of antibacterial activity and and protein in porcine pancreatic juice. Pancreas. 28:e32-e38.
Interpretive Summary: Disease causing and food borne bacterial pathogens are a constant challenge for farmed animals. Through a combination of natural and adaptive immune functions in the gastrointestinal tracts it may be possible to protect against pathogen establishment in the gut and prevent diseases. An important component of the innate responses is the secretion of antimicrobial peptides (AMP) by the pancreas, as pancreatic AMP's appear to have a broad spectrum activity against many bacterial pathogens. Little is known about the regulation and amount of AMP secretions in pancreatic juice. The present study utilized internal antibiotic standard to quantify antibacterial activity in porcine (pig) pancreatic juice. Samples of pancreatic juice were collected at hourly intervals to determine the effect of feeding time and digestive state (pre-feeding, gastric and intestinal phases of digestion, and non-feeding) on the level of antimicrobial peptides. The goal was to determine if the secretion pattern of AMP was always present, induced by a stimulus, or a combination of both. Protein content of samples was measured as an indicator of total peptide secretion. Antibacterial activity was measured using micro titer methods. It was demonstrated that antibacterial activity of pancreatic juice did not correlate with total protein secretions, suggesting alternative signaling pathways. Other scientists will benefit from this research in exploring alternate pathways associated with AMP secretions. Such efforts will lead to formulating diets and treatment strategies, which will enhance animal resistance to pathogens.
Technical Abstract: The antimicrobial activity of exocrine pancreatic juice is an important component of gastrointestinal tract innate defenses, yet little is known about whether secretion is regulated in parallel with digestive enzymes. In this study, we used 8 pigs with pancreatic catheters to quantify antibacterial activity and measure protein content (indicator of enzyme secretion) of pancreatic juice collected hourly from 0700 - 1900, with the animals adapted to being fed at 0800 and 1600. Antibacterial activity in the samples of pancreatic juice was quantified by comparing the growth inhibition of Staphylococcus aureus subsp. Aureus strain ATCC 6538P relative to a known concentration of gentamicin. Antibacterial activity (units/ml and /min) was highest in samples collected 1 hour prior to feeding (equivalent to 0.6 mg gentamicin/ml), declined as the meal was consumed, and was lower (P<0.05) in samples collected while the meals were being digested (0.41 mg gentamicin/ml). Protein content was negatively correlated with antibacterial activity, with protein secretion lower (mg/ml and /min) before feeding, with an increase as the pigs ate and digested the meals (P<0.05). The results indicate that the antibacterial activity in pancreatic juice is not secreted in parallel with protein secretion, suggesting that regulation involves alternative signaling pathways or contrasting responses to shared signals.