Host-Microbe Interactions: Effects on nutrition and

physiology

Thomas E. Burkey

September 15, 2014

Allen D. Leman Swine Conference

Outline Introduction Microbial Diversity in the Gut Function of the gut microbiota Composition of gut microbiota is affected by diet “Gut Health” Defined Does health status affect gut microbial community

composition and function? Future Directions

Microbial Diversity in the Gut• The adult human gastrointestinal (GI) tract contains

all three domains of life—bacteria, archaea, and eukaryota.

• Human gut microbiota:

• 100 trillion archaeal and bacterial cells

• Distributed over 1000 species

• Dominated by bacterial species

• The most dominant divisions are the Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria.

Tremaroli & Backhed. Nature: 489, 242–249

Overview of microbial diversity of the human gut

Bäckhed et al., 2005

Host specific gut microbiota composition

Dethlefsen et al., 2007

Function of the gut microbiota Microbiota: collective microbial community inhabiting a

specific environment Microbiome: collective genomic content of a microbiota

(i.e., total genetic capacity of the community) Metagenome: total DNA that can be extracted from an

environment (i.e., aggregate of host DNA and microbiota DNA) Host bacteria, archaea, fungi, and yeasts convert

nutrients and host-derived substrates into various metabolites

Dynamic yet stable Microbiota composition differs in health and disease

Gut microbiota: protein metabolism

Dietary and host-derived (pancreatic juice, mucus, shed epithelial cells) protein is available for microbial fermentation.

Products included beneficial SCFAs and potentially toxic metabolites (e.g., ammonia, phenolic compounds, sulphides)

Vavassori et al. 2009. J. Immunol. 183: 6251.

Gut microbiota: carbohydrate metabolism

Principle products of fermentation: Gases SCFAs

Butyrate Propionate Acetate

Vavassori et al. 2009. J. Immunol. 183: 6251.

Gut microbiota: lipid metabolism

No evidence that ingested lipids are degraded by microbiota

However, dietary lipid is linked to bile acid secretion Bile acids can be transformed into bio-active

metabolites by gut bacteria Key players in primary bile acid deconjugation are

Bifidobacterium sp. and Lactobacillus sp. Bile acid metabolites are ligands for nuclear

hormone receptors (e.g., farnesoid X receptor; FXr) FXr signaling affects many gene targets

Bile acid synthesis/transport; lipid and carbohydrate metabolism, regulation of intestinal innate immunity

Vavassori et al. 2009. J. Immunol. 183: 6251.

Composition of gut microbiota is affected by diet

Enterotype 1, enriched in Bacteroides: associated with diets rich in animal fat/protein

Enterotype 2, enriched in Prevotella: associated with diets rich in carbohydrates

Enterotype 3, enriched in Ruminococcus: not well defined

Arumugam et al., 2011Nature: 473, 174–180

Human Example: Impact of diet in shaping gut microbiota

Comparison of fecal microbiota of European children and children from rural Africa

Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14691-6

Nutrient x Health Interactions: Models to explore the effects of gut microbes on porcine health and growth performance

Effect of dam parity on litter performance, transfer of passive immunity, and progeny microbial ecology (Carney-Hinkle et al., 2013)

Effects of diet on growth performance and gut health in healthy pigs DDGS (Tran et al., 2011)

Lactose and yeast-dried milk (Tran et al., 2012)

Chicory (inulin) (Mastromano et al., 2014)

Spray-dried porcine plasma (Tran et al., 2014)

Effects of diet on growth performance and gut health in sick pigs PRRSV PCV2

Effect of corn distillers dried grains with solubles on growth performance and health status indicators in weanling pigs (Tran et al., 2012)

Pigs fed DDGS may have increased microbial similarity and decreased bacterial diversity, as well as reductions in microbial richness

Effects of lactose and yeast-dried milk on growth performance, fecal microbiota, and immune parameters of nursery pigs (Tran et al., 2012)

The effects of lactose and yeast-dried milk on Lactobacillus composition at d 0, 7, and 14 postweaning At weaning (d 0), no differences among treatments for fecal

Lactobacillus staining intensity. At d 7 postweaning, pigs fed lactose with or without yeast-dried milk

had greater (P < 0.05) staining intensity of putative L. johnsonii when compared with the control pigs.

At d 14 postweaning, control pigs had greater putative L. delbrueckii (P < 0.04) and tended to have greater L. sobrius/amylovorus (P = 0.10).

Microbial transmission and assembly of gut microbiota in neonatal pigs on d 7 and 14 postfarrowing.

Hinkle et al. 2011. J. Anim. Sci. 89(E-Suppl. 2): 662. (Abstr.)

Differences in core microbiota between P1 and P3 dams and their progeny.

Hinkle, E.E. et al. 2012. Proc. 12th Int. Symp. Dig. Phys. Pigs. Keystone, CO.

Effects of spray-dried porcine plasma on fecal microbiota in nursery pigs

Ion Torrent profiling sequences target gene based on pH fluctuation during nucleotide chain synthesis

Relative abundance of major phyla (A), families (B), and genera (C) in pigs fed control and SDPP diets across a 4-wk feeding period.

Effects of spray-dried porcine plasma on fecal microbiota in nursery pigs

Feeding SDPP alters fecal microbial communities in pigs May decrease pathogenic

bacteria (e.g., C. difficile, E. rhusiopathiae, B. helcogenes)

May increase cellulose degrading bacteria (e.g., Clostridium sp. and Ruminococcus sp.)

May increase butyric acid-producers (e.g., Lactobacillus sp. and Megasphaera elsdenii)

Distribution of shared OTUs in pigs fed spray-dried porcine plasma compared to control pigs.

“Gut Health” Defined Linking diet, gut enterotypes, and health?? …”a state of physical and mental well-being in the

absence of GI complaints that require the consultation of a doctor, in the absence of indications of or risks for bowel disease and in the absence of confirmed bowel disease”.

Five major criteria for a healthy gut Effective digestion/absorption Absence of GI illness Normal and stable intestinal microbiota Effective immune status Status of well-being

Bischoff, S.C. 2011. ‘Gut Health’: a new objective in medicine? BMC Medicine. 9:24.

“Gut Health”: Underlying Mechanisms

Bischoff, S.C. 2011. ‘Gut Health’: a new objective in medicine? BMC Medicine. 9:24.

Functional entities to maintain Gut Health

GI Microbiome Energy homeostasis Mucosal infection Mitigates immune hypersensitivity Contributes to maintain GI barrier

GI Barrier Epithelial defense Metabolic function Mucosal immune system Enteric nervous system

Microbial markers of dysbiosis

Rajilić-Stojanović, 2013

Does health status affect gut microbial community composition and function? ……….PRRSV model The impact of PPRSv on feed efficiency, digestibility

and tissue accretion in grow-finisher pigs Objective: Characterize the impact PRRSv challenge

has on Feed efficiency, energy and nutrient digestibility Body composition and tissue accretion Post-absorptive metabolism

Hypothesis: The reduction in growth rates during PRRSv infection is associated with reduced energy and nutrient digestibility

Impact of PRRSv on body composition and tissue accretion DXA predicts total mass, lean, fat, and

bone mineral density/content

Effects of PRRSv challenge on Apparent Total Tract Digestibility (ATTD) 21 dpi

65 dpi

How do you explain the long term negative impact on ATTD?

What is the metabolic cost of disease challenge? Energy

Immune response Nitrogen clearance Changes in metabolic rates

Amino Acids Synthesis of immune cells Gluconeogenesis

Metabolic Shift? Up-regulation of glycolysis Amino acids: immune proteins, gluconeogenic

intermediates

Metabolic Shift? Poorer growth

responding pigs to PRRSv Higher blood glycerol,

urea, and lactate Lower blood glucose,

pyruvate and citrate

Pigs that regulate metabolic shifts (oxidative to glycolytic metabolism) may handle immune challenges better? This appears to be

also influenced by genetic selection for disease tolerance

How do you explain the long term negative impact on ATTD? Changes in gut microbial community, metabolites???

Does health status affect gut microbial community composition and function? …….PCV2 model The effects of PCV2 on growth performance of pigs

fed simple vs. complex diets Objective: Characterize the effects of simple vs

complex diets on pigs challenged with PCV2 Hypothesis: Diet complexity will have differential

effects on growth performance of pigs challenged with PCV2 96 barrows; 33 d of age; 7.1 kg initial BW PCV2 status (vaccinated v infected) Diet type (complex, simple, simple + probiotic)

The effect of PCV2 on BW, kg

Overall = 0.061

The effect of diet type on ADG, kg

The effect of diet type on ADFI, kg

Effect of PCV-status and diet type on digestibility…..gut microbial community…..

?

Areas of opportunity Five major criteria for a healthy gut

Effective digestion/absorption Absence of GI illness Normal and stable intestinal microbiota Effective immune status Status of well-being

Can we quantify to further define “Healthy Gut”?

Areas of opportunity Understanding how the diet affects the microbiome

and how the metagenome is affected by diet in both healthy and sick pigs……. Reduced feed intake/digestibility Reduced tissue accretion Long lasting impact on feed efficiency Glycolytic shift may be important

Altered nutrient requirements? Increasing appetite Lowering energetic cost of disease Potential dietary interventions

Areas of opportunity Development of pre- and probiotics?

Synbiotics? Lactobacillus reuteri competition

experiment

Areas of opportunity

Development of a cecum cannulated pig model to evaluate gut microbial community dynamics and function at the molecular and physiological levels Gut Microbial triggers that influence

the disease associated phenotype Can microbial gene expression be

evaluated to understand microbial function?

Allows for repeated real-time monitoring of the gut microbiome

Acknowledgments USDA – Animal Health Formula Funds National Pork Board

Grant# 12-163 Iowa Pork Producers Association

Grant# 12-113 Choice Genetics International Ingredient Corporation Drs. Gabler, and Odle, laboratory staff and students Drs. Miller, Fernando, Walter, and Hostetler, laboratory staff and

students