1. Gluten: Friend, Foe or Fad?
Understanding Society’s Most Unpopular Protein

2. What is Gluten?
Wheat
Rye
Barley
sdf
Vague?!
gliadin
glutenin
gluten

3. What is Gluten? Glutenins Gliadins 47% total protein content
Fibrous aggregates of high and low molecular weight subunits
HMW glutenins rich in cysteine
Intermolecular disulfide bond formation
~45% total protein content
Globular in structure
38-45% glutamine
15-30% proline
Intramolecular disulfide bond formation
Glutamine – energy storage – glutamate/glutamic acid
Proline – structural implications – prevents alpha helix formation, makes beta sheet formation challenging – favors intramolecular
glutamine
proline

4. Gluten Network Formation
gliadin
glutenin
gluten
Hydration
Oxidation
Kneading
Hydration
Oxidation
Kneading
H2O
Relaxation & expansion of insoluble network OH O
NH2 SH α S
Oxidizing agent
+ H+ + e- OH O
NH2 S α S
disulfide bond

5. Gluten Network Formation: Direct Oxidizing Agents
Oxidation of cysteine…
Azodicarbonamide ?

6. Gluten Network Formation: Direct Oxidizing AgentsSH HS
+ KBrO3
Iodate S S
+ 3H2O + KBr
Bromate

7. Gluten Network Formation: Indirect Oxidizing Agents
ascorbic acid oxidase
(enzyme)
+ 2H+ + 2e-
Ascorbic acid
Acts as oxidizing agent for GSH
Dimerization of GSH S
Glutathione (GSH)
Glutathione disulfide (GSSG)
Prevents GSH from forming disulfide bonds with cysteine… indirectly

8. Gluten Network Formation
Early Kneading Mid-Kneading Late Kneading

9. Gluten Network Prevention
Free L-cysteine
Non-Leavening Yeast
Network formation S S S
Network prevention S S S S
Oxidized glutenin

10. Gluten Network Destruction
“Bran Slashing Theory”
CO2
CO2
CO2
CO2
“slashed” gluten
gluten network

11. Gluten Formation & Bread Texture
Porosity
Loaf volume

12. Gluten Formation & Bread Texture
Inflation
Dough extensibility

13. Gluten Formation & Bread Texture
Compressibility: objective measurement of “soft” vs. “hard”

14. Celiac Disease

15. Celiac Disease Autoimmune enteropathy stimulated by gluten consumption
Affects 3 million Americans, 1% of global population
Estimated 1 in 133 Americans are living undiagnosed
More common in individuals of western European descent
Difficult to diagnose
Permanent damage to small intestine, increased risk for other chronic diseases

16. Symptoms and Disease State
GI discomfort
Skin rash (dermatitis herpetiformis)
Iron deficiency anemia
Muscle cramps/joint pain
Growth problems/failure to thrive
Prolonged exposure
Chronic intestinal inflammation
Loss of small intestinal structure (villous atrophy, crypt hyperplasia)
Decreased nutrient adsorption
Increased risk for osteoporosis, lymphoma, intestinal cancers
Celiac Disease
Normal

17. Celiac Disease Pathogenesis1
Initiation of intestinal permeability 2
Translocation of gliadin fragments 3
Inflammation/damage
Apical 4
TG2 deamidation 5
MHC-class II complex formation, T cell proliferation, IgA release
Basolateral

18. Gliadins and Celiac Disease: A Structure-Function Relationship
High proline frequency causes polyproline helix formation, which is the preferential structure for…
Deamidation of Gln by TG2
Gln-X-Pro
MHC-class II complex formation
Gliadin + HLA-DQ2/8
Immunodominant αII-gliadin 33mer, Gln residues that undergo deamidation highlighted in yellow.
Epitopes
α-I
α-II
α-III
LQLQPFPQPQLPYPQPQLPYPQPQLPYPQPQPF

19. Risk Factors Genetic Environmental
Blood marker: Human Leukocyte Antigen DQ-2/8
HLA-DQ2: 95% of CD patients
HLA-DQ8: remaining 5%
5-22% of individuals with CD have a 1st degree relative with the disease
Environmental
Only 35-50% of HLA-DQ2/8 individuals have CD… what is the missing link?
Existing theories…
Exposure
Gut microbiota

20. Development of Diagnostic Criteria… without an endoscopy.
Why the sudden onset?
Development of Diagnostic Criteria… without an endoscopy.
Signs of CD upon gluten consumption
Elevated levels of antibodies for self-enzyme tissue transglutaminase 2
Elevated levels of IgA
HLA-DQ2/8 haplotype

21. Therapies & Developing Treatments
Gluten-free diet
Synthetic enzyme supplementation
Protein sequestration
Hookworm infection

22. Gluten-Free Living

23. Why are some people doing this for fun?

24. What is the point?
“The gluten-free diet for someone with Celiac disease is like insulin for diabetics.”
Alessio Fasano, M.D.
Director of the Center for Celiac Disease Research, Massachusetts General Hospital

25. Non-Celiac Gluten Sensitivity
NCGS sufferers describe CD-like symptoms, but diagnostic tests come back negative…

26. NCGS: Why We Can’t Make a Decision… Yet.
Large population-based studies have shown very few individuals reporting NCGS actually have symptomatic responses to gluten
Responses/pathologies not consistent between individuals
Placebo effect / diet overhaul skews personally-reported
We don’t fully understand CD etiology or the impact of environmental factors on many gut-related diseases
What do YOU think?

27. Active Learning What was the most interesting thing you learned today?
What is something that you’re still wondering about?
What is a hypothesis that you would like to test, related to today’s topics?