Physiology of the Weaner Pig

Transcription

1 Physiology of the Weaner Pig Microbiota,, Gut Immunity and Performance Denise Kelly, Rowett Institute of Nutrition & Health, University of Aberdeen, Scotland Gut surfaces and Epithelial cells Gut Bacteria LP ES mucin Gut Lamina Propria LP Immune Education and Maintenance

2 Gut Microbiota and Gut Health Development of the Gut Microbiota Hygiene Hypothesis Gut Microbiota and Immune Development How Bacteria influence Mucosal Immune Function Impact of Environment on Microbial Diversity and the developing pig gut (GUTWEAN) Next generation probiotic products

3 Gut Microbiota and Gut Health trillion organisms (1.5kg) bacterial species 10X more bacteria than host cells 100X more bacterial genes than host genes (>3 million nr microbial genes) Metabolic functions eg. carbohydrate fermentation, vitamins, lipid, amino acid and xenobiotic metabolism Qin et al Nature 464, Trophic functions eg. epithelia, angiogenesis Disease resistance eg. C. difficile Immune functions eg. development and regulation

4 The Adult Gut Microbiota Microbial Diversity Dominated by 3 Major Phyla Bacteroidetes Firmicutes Actinobacteria Strong similarity in humans and pigs Eckburg/Relman 2005, Science

5 Lifetime Stability of the Gut Microbiota Early life Adult Aging Spro, Koren & Ley 2011 Nature Reviews Microbiology 9,

6 Maternal to Neonatal transmission shapes the acquisition and structure of the early microbiota The Importance of Maternal Bacteria in Colonising the Gut Dominguez-Bello et al 2010 PNAS

7 Antibiotic usage influences Microbiota Composition Ichinoche et al 2011 PNAS Antibiotic-treated mice tones and Purple and yellow denote gram positive gram negative bacteria Faecal Nasal

8 Genetics and Gut Microbiota

9 Genotype, Blood Group Antigens and Bacterial colonisation Sucking/Weaning Transition Newborn Sucking Suckling piglet Weaned piglet

10 Environment an Important source of Gut Microbes Hygiene Hypothesis Dirty Environment Clean Healthy Diseased Reduced exposure to infectious diseases and microbial products associated with a clean ( hygienic ) lifestyle has been linked to impairment of immune function

11 Altered Microbial Diversity in Several Diseases Healthy Diseased IBD Spor et al Nat Rev Microbiol Unravelling the effects of the gut microbiome and immune/metabolic health

12 MICROBIOTA COMPOSITION IS ESSENTIAL FOR IMMUNE HOMEOSTASIS AND BALANCE Probiotic Pathogen Balance between symbionts good bacteria and pathobionts bad bacte

13 Peyer s Patches (PP) and Lamina Propria (LP) Major organised lymphoid structures in the gut Inductive Site for Mucosal Immunity PP Effector Site for Mucosal Immunity (PP) (LP) M cells Important for immune responses to commensal bacteria (tolerance) And pathogens (active immunity) Microfold (M cells) Specialised epithelial cells (PP) Allow efficient sampling of particulate antigens

14 The Germ-Free Pig Gut has No Immune System Colonisation by Gut Bacteria Drive the Development of the Immune System Little development of mucosal immune system in germ-free neonatal piglets No development of intraepithelial lymphocytes Lamina propria T cells do not appear in significant numbers No increase in CD4+ and CD8+ lymphocytes in the lamina propria Peyer s patches remain small

15 Imprinting of Gut Immune System by the Commensal Microbiota Germ-free Mice with normal gut microbiota Experiments with germ-free reveal many different systems are shaped by the microbiota Stimulation of immune system requires high doses of bacteria Live bacteria are better stimulus for immune system than dead Hypoplastic Cellular Expansion

16 Bacteria interact with Epithelial cells and dendritic cells Epithelial cells (ECs) First line of contact with bacteria Dendritic cells (DCs) key initiators and regulators of the adaptive immune response T regulatory cells (Tregs) cells critical in immune homeostasis. Important therapeutic targets in autoimmunity

17 Importance of Dendritic cells in Mucosal immunity Lamina propria and PP DCs are important for directing the function of T cells DC T cell

18 Tolerance versus Active Immunity T cells T cells Active immunity Tolerance Th1 /Th2/Th17 Th3 /Treg T cell Balance is critical to Gut Health Controlling Innate Immune Responses is important

19 Gut Health is Maintained by Balanced T cell responses T helper cells = T regulatory cells Th1, Th2, Th17 Th3, Tr1, Treg Immune Homeostasis/ Balance? What happens if the T cell balance is disturbed towards Th1

20 Imbalances in T helper cell/treg cell Function is associated with many Gut Disorders T helper cells Th1, Th17 > T regulatory cells Th3, Tr1, Treg Inflammatory and Autoimmune diseases Excessive Th1 and Th17 is associated with chronic inflammation Eg. Crohn s Disease/ Inflammatory Bowel Disease (IBD)

21 Allergic Diseases Associated with Excessive Th2 Responses T helper cells > T regulatory cells > Th2 Th3, Tr1, Treg Allergic disease Excessive Th2 associated with chronic inflammation Eg. Allergic and atopic diseases

22 GutWEAN Project Understand the Mechanisms of Microbial Colonisation and their interactions with the pig immune system Provide insight into the ways to produce Pathogen-Free Pigs, with Less Reliance on Antibiotic Use Identify potential next generataion probiotics with defined mode of action that are fit for purpose

23 GutWEAN Project Understand the Mechanisms of Microbial Colonisation and Develop Immuno-Competent, Pathogen-Free Pigs, with Less Reliance on Antibiotic Use Bacteria which promote healthy gut function Identify bacterial species that drive the functional maturation of the immune system Identify candidate molecular markers of mucosal immune system development 16S rrna DGGE and gene library analysis On Gut ileal tissue Affymetrix microarray gene expression analysis On Gut ileal (immune) tissue

24 Experimental Design Indoor housed sows (N=6) Outdoor housed sows (N=6) Sows Each sow has litter of >9 piglets Each sow has litter of >9 piglets Treatment 36 piglets transferred to isolator at 24h Antibiotics 18 piglets left on sow 36 piglets transferred to isolator at 24h Antibiotics 18 piglets left on sow Sampling Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6)

25 Outdoor, Indoor and Isolator Environments Indoor environment Outdoor environment Isolator facility

26 Comparison of Treatment 'Extremes' Indoor housed sows (N=6) Outdoor housed sows (N=6) Sows Each sow has litter of >9 piglets Each sow has litter of >9 piglets Treatment 36 piglets transferred to isolator at 24h Antibiotics Clean Testing the Hygiene Hypothesis 18 piglets left on sow Sampling Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Dirty Day 5 (N=6) Day 28 (N=6) Day 56 (N=6)

27 Comparison of Indoor and Outdoor Environment Indoor housed sows (N=6) Outdoor housed sows (N=6) Sows Each sow has litter of >9 piglets Each sow has litter of >9 piglets Treatment 18 piglets left on sow 18 piglets left on sow Sampling Day 5 (N=6) Day 28 (N=6) Day 56 (N=6) Day 5 (N=6) Day 28 (N=6) Day 56 (N=6)

28 Scientific Impact

29 Fluorescence in situ Hybridization (FISH) of Ileal Gut Sections Universal eubacterial probe Bacteroides specific probe (Eub338) (Bac303) Localisation of common bacterial species (existing probes) Localisation of newly found species (16S probe design)

30 Genomics, Bioinformatics and Identifying Novel Pathways of Immune Education Affymetrix GeneChip Porcine Genome Array Quality Control Pathway Analysis Clustering Analysis Genelist of differential expression Day 5 Day 28 Day 56 Gene Ontology Enrichment

31 100% 75% 50% 25% 0% Early-life Environment Significantly Alters Microbial Mucosa-Associated Diversity Outdoor Sow reared Firmicutes Indoor Sow reared Firmicutes Indoor Isolator + Antibiotics Clostridia Lactobacillales Proteobacteria Bacteroidetes Other Peptostreptococcaceae Clostridiaceae Veillonellaceae Lachnospiraceae Ruminococcaceae Leuconostocaceae Streptococcaceae Lactobacillaceae Bacillales Erysipelotrichi Gammaproteobacteria Betaproteobacteria Epsilonproteobacteria Alphaproteobacteria Prevotellaceae Bacteroidaceae Porphyromonadaceae Actinobacteria Phylogenetic Distribution of 16S rdna Sequences Mulder et al BMC Biology Firmicutes Proteobacteria Bacteroidetes

32 Lactic Acid Bacteria Derived from Outdoor Pigs Lactic acid producing bacteria DGGE product amplified using specific primers (primers from Walter et al., 2001) DGGE Analysis: DGGE profile of LAB in the treatment comparisons at day 56. The dendrogram showed a distinct LAB profile for the OS group (70 80% similarity), separate from the indoor reared treatment groups. Comparisons of DGGE pattern profiles were performed using Dice's similarity coefficient and the similarity was visualised by dendrograms using the UPGMA algorithm. Organic Lactobacilli are highly adapted to the bioenvironment

33 Microbial Colonisation in Early Life Influences Immune Development ent Outdoor versus Indoor Isolator+Ab Day 5 Day 28 Day 56 Upregulated genes Downregulated genes IS+Ab IS+Ab IS+Ab IS+Ab IS+Ab IS+Ab OUT OUT OUT OUT OUT OUT Genes in common between comparisons

34 Environmental Impact on Gene Expression is Maximum at Day Indoor Sow-reared vs Outdoor Sow-reared Day 5 Day 28 Day 56 Upregulated genes Downregulated genes Genes in common between comparisons OUT OUT IN OUT OUT OUT IN IN OUT IN IN IN

35 Inflammation significantly lower in Outdoor Sow reared compared to Indoor Isolator + Antibiotics IRF7 STAT1 STAT2 ISGF3G PRKR MX1 IFIT1 IFIT2 IFIT3 Viperin IRP6 Histocompatibility 28 MHC I antigen B*7 Day 5 Day Day 56 CCL28 CCL2 G1P2 MX2 CXCL12 CCR5 MHC class I B*7 Pyruvate dehydrogenase kinase isoform 4 Differentially Expressed Genes and Potential Biomarkers of gut health

36 Strong induction of tolerance inducing Treg cells A p=0.01 p=<0.001 in outdoor farm-reared pigs CD4+ T-cells in the lamina propria of the small intestine in 28 day old piglets. Numbers of CD4+FoxP3+ T-cells in the lamina propria of the small intestine. B p=0.005 p=0.007 p=0.027 p=0.01 Foxp3+CD4+ T-cell in the intestinal mucos A, Foxp3 identified by FITC; B, CD4 identified by TRITC; C, DAPI; D, merge. Foxp3+ cells are rare and Foxp3 is largely nuclear

37 Outdoor pigs maintain control of microbiota and are strongly immunotolerant Strong induction of tolerance responses to soya in outdoor farm-reared Isolator m Far Isolator m Far

38 Promoting Gut Health Next generation of host-specific probiotics Restriction of growth-promoting antibiotics in animal feeds has led to renewed interest in the use of probiotics as growth promoting agents JAN 2006 Antibiotic withdrawal Probiotics with proven efficacy Restoring microbiological balance Restoring immunological balance Improving performance

39 Take Home Messages Gut bacteria drive development of the immune sys Development needs to be controlled Homeostasis is less energy costly than active inflammatory responses that occur in the absence of regulation and control Certain probiotic bacteria are specialised to regula the immune system and offer a route to improving post-weaning performance

40 Acknowledgements Rowett Institute of Nutrition and Health Gut Immunology Group Dr Imke Mulder Dr Bettina Schmidt Dr Rustam Aminov Biomathematics and Statistics Scotland Dr Claus-Dieter Mayer Dr Tony Travis Corran Musk Genomics Facility Gill Campbell Pauline Young University of Aberdeen Institute of Medical Sciences Microarray Core Facility Dr Elaina Collie-Duguid Diane Stewart Division of Veterinary Pathology, Infection and Immunity Bristol Veterinary College Professor Chris Stokes Dr Mick Bailey Dr Marie Lewis