28/10/18

Allergy prevention by raw cow’s milk - Epidemiological evidence and possible involved mechanisms

Agnes Wold Professor of Clinical Bacteriology University of Senior Consultant, Sahlgrenska University Hospital

IgE-mediated (atopic) allergy– our most common disease

• ~ 30% of children and young adults affected inWestern countries • Increases globally when living standards improve • Often life-long disease • Significant negative effects on quality of life • Tremendous costs in medications & lost productivity

NO effective preventive measures yet found

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Allergens = common, harmless proteins in environment (food, air)

Fel d 1 (cat) Beta-lactoblogulin (cow’s milk) Bet v 1 (birch pollen)

Sensitization = presence of allergen-specific IgE antibodies

IgE venule

Bet v 1

Symptoms = allergy

Tissue swelling, mucus histamine production, vasodilatation Hay fever, asthma, atopic eczema, food reactions (vomiting, skin eruption) mast cell

”The atopic marsch” IgE-mediated allergy

food allergy allergy to aiborne allergens

symtom: eczema asthma GI symptoms hay fever

1 yr newborn 3 yr

adult

allergens:

cow’s milk animals pollens egg

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A normal, healthy reacts to microbes, but tolerates harmless protein (Oral tolerance)

food proteins microbes

?

? Peyer’s patch

How? IMMUNITY ACTIVE, - SPECIFIC TOLERANCE Where? regulatory T cells Which type?

As infections decrease, immunoregulatory diseases increase

JF Bach The effect of infections on susceptibility to autoimmune and allergic diseases. N Engl J Med 2001

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Immune regulatory disorders • Most common in rich countries inflammatory • Increasing last decades, X bowel disease continued increase

Immun- system Immune system ”allergens”

allergy µ autoantigens microbes autoimmunity

Hay fever – rare among farmers

30% allergy

1819 ”Catharrus aestivus”

prevalence (hay fever)

1800 1850 1950 2000 Charles Blackley MD with hay fever 1873 year Hay fever= reaction to grass pollen ”Why, then, do the farmers and their families have the fewest cases of this disorder?” Hay fever, 1926: City pop: 1,3% Rural pop: 0,1%

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Rediscovery of the protective effect of growing up in a farming milieu, studies 2000 → from many countries:

Austria Germany France Switzerland Finland Denmark Sweden Spain Canada Australia

Protective factors: 1) Exposure to stable milieu 1st yr 2) Mother in stables during pregnancy 3) Raw milk consumption

Which factors may explain the protective effect of farming on allergy? Children 6-13 years, Germany, Austria, Switzerland 35 30 No farm 25 Farm 1st year 20 Farm+ raw milk 1st yr 15 Raw milk 1st yr 10 5 Farm only after 1st yr 0 Hay fever Asthma IgE (sens)

Farm is most protective 1st year of life Farm + raw milk most protective Riedler J, Braun-Fahrländer C, Eder W, Schreuer Raw milk consumption 1st yr: M, Waser M, Maisch S, Carr D, Schierl R, Nowak D, von Mutius E; ALEX Study Team. • 3 x less hay fever Exposure to farming in early life and development • approx. 40% less asthma, IgE of asthma and allergy: a cross-sectional survey. (sensitization) Lancet. 2001;358:1129-33.

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The allergic march starts very early

The first year of life is most important in determining the risk of developing allergy even if the allergic symptoms may appear in adolescence…

Protective measures must target the neonatal infant (or even the fetus during late pregnancy)

Equal or better protection from raw milk in non- farming children

2.8x↓ 2.9x↓

4.8x↓ %children sensitized (IgE) Parents: No farm Farm workers Farmers protection by raw milk PROTECTION protection by raw milk

Raw milk consumption Perkin MR, Strachan DP. Which aspects of the farming lifestyle explain the inverse association No consumption of raw milk with childhood allergy? J Allergy Clin Immunol. 2006;117:1374-81.

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Raw milk consumption in town children – less sensitization

3.7x↓ 25 Children 11-19 år, 20 Heraklion, Crete

15 Sensitization to common aeroallergens 10 Allergens: grass pollen

%sensitized 5 (Mediteranean species), mites, cat, Parietaria, goat, olive 0 flowers, Alternaria (mold)

Consumption of raw milk

Barnes M et al. Crete: does farming explain urban and rural differences in atopy? Clin Exp Allergy 2001;31:1822-8

Summary, clinical studies on effect of raw milk on allergy

11 cross-sectional and 1 cohort study shows protection against sensitization and/or allergy from consumption of cow’s milk

The putative protective effect is independent of exposure to farming environment

Putative protective effect is quite strong: 2-4 x reduction

Is raw milk to infants (in addition to breast feeding/bottle feeding) a possible way to reduce allergy development?

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Which milk components may explain the protective effect of raw milk? ? Live immune cells

macrophages Live bacteria T-cells (many activated) Fat droplets enclosed in Biologically phospholipid active proteins membrane

Denaturing Homogenization

The live bacteria?

Maybe not the most important factor

Human breast milk is also full of bacteria

- same groups are found in human and cow’s milk: CoNS, S. aureus, Pseudomonas, Klebsiella, group B streptococci etc.

Hypothesis: Microbiologically clean raw milk will be equally protective

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The live immune cells?

macrophages T-cells (many activated) (with ingested lipid droplets

Live milk cells affect infant’s immunity MHC child’s immune cells live milk cells tolerance to cell-bound (from mother) antigens live and active Maternal milk cells gut lumen cross the gut wall and of infant appear in the infant’s MHC circulation

Maternal milk cells circulate for some days in immunologically active state (temporary DTH positivity in breast-fed infants to tuberculin+ This phenomenonon may serve to mothers) protect against transplantation reactions between milk and child Maternal MHC are actively tolerized by (mother and child partially tissue breastfed offspring incompatible) (shown in humans, mice)

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Hypothesis – cow’s milk cells transfer tolerance

tolerance to antigens in/on cow’s milk macrophage live cow’s milk cells beta-lactoglobulin

gut lumen of infant

Cow’s milk macrophages contain not only cow’s milk proteins, but also pollen proteins, cow’s milk insulin… Tolerance to a broad range of environmental antigens

Milk is a living tissue with tolerogenic properties

But allergy to milk is very common

How does tolerogenic milk become highly allergenic?

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What happens when you pasteurize/homogenize? phospholipid bet v 1 (birch pollen) membrane beta-lactoglobulin 4 µm

Pasteurization/ lipid droplets homogenization creates a perfect immunogenic mixture homogenization cow insulin heat (pasteuriz.) 0.5 µm disrupted cells, DNA etc. 64 x ↑surface size, phospholipid cannot heat shock cover → protein hydrophobic surface ↑ immuno- fragmented bacteria. genicity + LPS etc

oil in water emulsion =Freund’s (=Freund’s incomplete adjuvant) complete adjuvant)

In order to test the possible tolerogenic effect of raw cow’s milk on infants, safety must be guaranteed How do we produce microbiologically safe raw milk?

• Selected farmers, thoroughly supervising the process • Catharina Berge • Screen each batch by running milk filter eluent through multiplex PCR for EHEC, Campylobacter, Salmonella (+ …?) • PCRs for faecal pathogens detect 1dead bacterium, e.g. of EHEC Sweden: 40 000 new persons with allergy each year (population 10 million). 20 000 cases of allergy yearly could be spared

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Allergy = immune mediated hypersensitivity

IMMUNE response CLINICAL picture

Tolerance No symtoms

No symptoms = Activation clinical tolerance harmless ”Sensitization” substances Symptoms = in food/air allergy (”allergens”) IgE

Rediscovery of the allergy-protective effect of farming Children raised on small family farms in Bavaria

2 x less sensitization 30

20 Farm 1st year Control 10

% av barnen som utvecklar som utvecklar barnen % av 0 IgE hay fever asthma 11 x less asthma 4 x less hay fever Riedler et al. Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey. Lancet 358:1129-33, 2001

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