In-feed resin acids reduce matrix metalloproteinase activity in the ileal mucosa of healthy broilers without inducing major effects on the gut microbiota

Marisol Aguirre,Hannele Kettunen,Eija Valkonen,Freddy Haesebrouck,Evy Goossens,Chana Callens,Juhani Vuorenmaa,Richard Ducatelle,Filip Van Immerseel

doi:10.1186/s13567-019-0633-3

Abstract

The chicken gut is constantly exposed to harmful molecules and microorganisms which endanger the integrity of the intestinal wall. Strengthening intestinal mucosal integrity is a key target for feed additives that aim to promote intestinal health in broilers. Recently, dietary inclusion of resin-based products has been shown to increase broiler performance. However, the mode of action is still largely unexplored. Coniferous resin acids are known for their anti-microbial, anti-inflammatory and wound-healing properties, all properties that might support broiler intestinal health. In the current study, the effect of pure resin acids on broiler intestinal health was explored. Ross 308 broilers were fed a diet supplemented with coniferous resin acids for 22 days, after which the effect on both the intestinal microbiota as well as on the intestinal tissue morphology and activity of host collagenases was assessed. Dietary inclusion of resin acids did not alter the morphology of the healthy intestine and only minor effects on the intestinal microbiota were observed. However, resin acids-supplementation reduced both duodenal inflammatory T cell infiltration and small intestinal matrix metalloproteinase (MMP) activity towards collagen type I and type IV. Reduced breakdown of collagen type I and IV might indicate a protective effect of resin acids on intestinal barrier integrity by preservation of the basal membrane and the extracellular matrix. Further studies are needed to explore the protective effects of resin acids on broiler intestinal health under sub-optimal conditions and to elaborate our knowledge on the mechanisms behind the observed effects.

Highlights

The chicken intestinal mucosa represents a barrier that protects the body against antigens, microbial toxins, invasive pathogens and toxic molecules taken up with the diet
Influence of resin acids on the caecal and ileal microbial diversity The microbial complexity in the ileum and caecum of broiler chickens was estimated by calculating the number of observed operational taxonomic unit (OTU), the estimated OTU richness (Chao1) or the estimated community diversity (Shannon index) in each sample
Addition of resin acids to the diet resulted in a significant differentiation of the ileal microbial community structures as compared to the control group (ANOSIM statistic R = 0.23, p = 0.002), whereas no statistical difference could be observed in the caecum (ANOSIM statistic R = 0.12, p = 0.055) (Figure 2)

Summary

Introduction

The chicken intestinal mucosa represents a barrier that protects the body against antigens, microbial toxins, invasive pathogens and toxic molecules taken up with the diet. Numerous studies show that disturbances in the intestinal ecosystem have profound consequences on animal performance, health and welfare [1,2,3]. Regulatory and consumer pressure to reduce antimicrobial usage in production animals has encouraged studies on alternatives to antimicrobials. Resins derived from coniferous trees are phytochemicals that were used since ancient times in Asian and Scandinavian traditional human medicine. These resinbased products are mainly used for treating wounds, Aguirre et al Vet Res (2019) 50:15 sores, pressure ulcers and a variety of other skin problems [20,21,22]. The effects of resins are presumed to be powered by their characteristic cocktail of terpenes (including abietic, dehydroabietic, neoabietic, isopimaric, levopimaric and palustric acids), which display a wide range of pharmacological properties, including, amongst other, anti-microbial, anti-tumor and anti-inflammatory activities [20, 27,28,29,30,31,32,33,34]

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