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Increased Intestinal Permeability (Leaky Gut)

Close-up Slice of a Small Intestinal Villus Showing How Enterocytes Appear Tightly Lining the Entire Outside Surface Of A Villus. Courtesy Cleo Libonati

What Is Increased Intestinal Permeability?

[dropcap]I[/dropcap]ncreased intestinal permeability is characterized by dysfunctional intestinal permeability (leakiness) allowing for the penetration of harmful entities from the gut into the bloodstream such as undigested proteins and microbes. The popular name is “leaky gut.”

Q: Why does intestinal permeability increase?

A: Intestinal permeability is an essential function of the small intestinal mucosal lining by which wanted substances such as properly digested foodstuffs are allowed to permeate through the lining to enter the body via the bloodstream and lymphatics. At the same time unwanted substances are kept out.

The mucosal lining is one cell thick and makes up the surface between the digested foodstuffs inside the hollow of the intestine and the underlying tissues.

The mucosal lining is covered by millions of microscopic finger-like structures called villi that project toward the inside of the intestine giving the appearance of a shag rug.

Each one, called a villus, contains a capillary bringing blood to absorb nutrients, a vein to take away nutrients, and a lacteal to absorb and take away digested fat. Its wall is made up of a single layer of tightly connecting cells, called enterocytes.

This single layer of cells separates the contents of our small intestine from the lamina propria (underlying tissues of the small intestine) and the rest of our body. Breaching of this single layer of cells by leakiness can expose lymphocytes (immune cells) located in the lamina propria to a myriad of microorganisms and food antigens, leading to immune reactions.1

To protect the body from unwanted substances, a gatekeeping barrier system operates to regulate the passage of nutrients, or permeation, through the surface mucosal lining. This system acts to seal the inside body from the gut.

The integrity of intestinal permeability is determined by interactions among several barrier components including the unstirred water layer, mucosal surface hydrophobicity, the surface mucous coat, and cell factors (especially tight junctions).

Tight junctions hold cells tightly together side-by-side to prevent unwanted substances from passing through the lining. Tight junctions are complex structures comprising over 50 proteins, such as the claudin proteins which are considered to be the structural backbone of tight junctions.

Tight junctions include a series of special proteins forming fibrils (springy like proteins) that cross the plasma membrane and interact with proteins in the adjoining cells. Tight junctions are regulated by the protein zonulin.2

If zonulin deregulates from the action of substances such as gliadin (gluten in wheat) and bacteria, the tight junction barrier fails which results in increased intestinal permeability. Dysfunction of the barrier system allows unwanted substances to enter the body where they are damaging to many tissues.

Tight junction dysfunction has been shown to be a part of certain autoimmune diseases such as celiac disease, type I diabetes mellitus, multiple sclerosis, and rheumatoid arthritis. Other diseases associated are cancer, allergies, and infections.3

Important gastrointestinal infections that cause leaky gut include rotavirus, parasites, pathogenic bacteria (escherichia coli, clostridium difficile), and mycotoxins produced by fungi found in stored grain and dried fruit.4

Fortunately, the presence of some commensal (friendly intestinal bacteria) and probiotic strains leads to an increase in tight junctions  proteins at the cell boundaries and in some cases prevents or reverses the adverse effects of pathogens, food and stress. Various dietary components are also known to regulate epithelial permeability by modifying expression and localization of  tight junctions proteins.2

What Is Increased Intestinal Permeability In Celiac Disease and/or Gluten Sensitivity?

Sources:
  1. Fahardi A, Banan A, Fields J, Keshavarzian A. Intestinal barrier: an interface between health and disease. Journal of Gastroenterology and Hepatology. 2003; 18: 479-497. [↩]
  2. Ulluwishewa D, Anderson RC, McNabb WC, Moughan PJ, Wells JM, Roy NC. Regulation of tight junction permeability by intestinal bacteria and dietary components. J Nutr. 2011 May;141(5):769-76. doi: 10.3945/jn.110.135657. [↩] [↩]
  3. Fasano A. Zonulin and Its Regulation of Intestinal Barrier Function: The Biological Door to Inflammation, Autoimmunity, and Cancer. Physiological Reviews. January 2011Vol. 91no. 151-175DOI: 10.1152/physrev.00003.2008 [↩]
  4. Farhadi A, Banan A, Fields J, Keshavarzian A. Intestinal barrier: an interface between health and disease. Journal of Gastroenterology and Hepatology. 2003;18:479-91. [↩]

Dysbiosis (Intestinal)

What Is Intestinal Dysbiosis? [dropcap]I[/dropcap]ntestinal dysbiosis is an imbalance of the composition and quantity of microbe populations (called the microbiota), that naturally inhabit our human gut. Dysbiosis causes altered gut immunity, abnormal fermentation of undigested foodstuffs,… 

Dermatitis Herpetiformis or Duhring’s Disease

Dermatitis Herpetiformis. Blisters Opened Giving Relief From Pain and Itching.
Dermatitis Herpetiformis On Forearm. Skin Is Darkened Where Old Blisters Healed.

What Is Dermatitis Herpetiformis?

[dropcap]D[/dropcap]ermatitis herpetiformis (DH) is an autoimmune extremely itchy, painful bullous skin rash (blistering eruptions) arising from the underlying dermis layer of skin as a consequence of gluten sensitivity.

Dermatitis herpetiformis is characterized by multiple intensely itchy, red blisters appearing on the elbows which can extend down the forearm to the wrist and the knees. Less usual areas involve the back, buttocks, scalp, and abdomen.

Q: Do the blisters leave a mark when healed?

A: Crops of skin eruptions begin with itching or a burning sensation in reddened papules. There are grouped vesicles and tense blisters. The blister contents may be serous or bloody, with symmetrical distribution (eg, both knees or both elbows). Fluid filled elements rupture leaving denuded areas of sore skin and crust. Subsequently, there is residual hypopigmentation (a white area) or hyperpigmentation (dark area).1

Rupture of blisters begins relief from intense burning and itching.

Dermatitis Herpetiformis Eruptions On Knees.
Dermatitis Herpetiformis Eruptions On Knees. Notice White Areas Showing Loss of Pigmentation From Healed Blisters.

What Is Dermatitis Herpetiformis In Celiac Disease and/or Gluten Sensitivity?

Primary care providers should be aware of this skin condition, as they are more likely than a gastroenterologist to be confronted with this type of presentation of celiac disease.2

Sources:
  1. Mendes FB, Hissa-Elian A, de Abreu MA, Gonçalves VS. Review: dermatitis herpetiformis. An Bras Dermatol. 2013 Jul-Aug;88(4):594-9. [↩]
  2. Robinson BL, Davis SC, Vess J, Lebel, J. Primary care management of celiac disease. Autoimmune Disorders. Nurse Practitioner. February 2015: Vol 40 – Issue 2; 28–34. [↩]

Gluten Sensitive Enteropathy (Active Celiac Disease)

canstockphoto17997339What Is Gluten Sensitive Enteropathy?

Gluten sensitive enteropathy is active celiac disease characterized by inflammation of the small intestinal mucosa that results from an inherited immunologic intolerance to ingested gluten.

Q: What does the inflammation do to the mucosa in the small intestine?

A: Inflammation is a cell level immune response to gluten that has these effects on the mucosa:

  • Damages the barely visible villi (multitudinous finger-like structures) by causing atrophy or loss.
  • Likely affects the structural support and microcirculation of the villus, leading to collapse of the villus.
  • Elongates the crypts between villi. The thickening of the crypt is not so much a response to loss of surface enterocytes but represents inflammation of the mucosa.1
  • Increases round cells in the lamina propria and surface epithelial cells leaving few, irregular microvilli (brush border) on the surface of villi.
  • Damage is most intense in the duodenum and decreases toward the large intestine.
  • The extent of the damage to the intestine determines the malabsorptive consequences of the disease. Both gastric and small intestinal permeability are disrupted in patients with celiac disease.2
  • Relationship between active celiac disease and intestinal permeability: There is a clear association between degree of mucosal damage and the intestinal-permeability ratio, and a normal ratio generally implies near-normal small intestinal structure. A raised intestinal permeability of the mucosal lining (leaky gut) could predispose to a high absorption of gluten and exacerbate an existing lesion and hence convert a latent to an overt enteropathy.3
  • Relationship between active celiac disease and tight junction proteins: A study of intestinal permeability showed that the expression of all junction proteins of the small intestinal lining (occludin, claudin 3, zonula occludens 1, and E-cadherin) was already decreased in early stage celiac disease when compared with non-celiac controls, showing leaky gut and confirming the above earlier study by Johnston et al. Junction protein expression correlated positively with mucosal villus structure and negatively with the number of intraepithelial lymphocytes (IELs), the intensity of small-intestinal autoantibody deposits, and serum autoantibodies. The expression of claudin 3 showed a negative correlation with diarrheal score.4
  • Relationship between active celiac disease and inflammation. In celiac disease there is an over production of inflammatory interleukin-15 (IL-15) which inhibits the correct removal of damaged intraepithelial lymphocytes caused by the reaction to gluten. Serum levels of IL-15 are directly correlated with the seriousness of tissue damage.5

  • Relationship between active celiac disease and gut microbiota. Results of a study investigating intestinal microbiota (normal bacterial residents) in patients with celiac disease suggest that with lower levels of the genus bifidobacteria, celiac patients have an imbalance in the intestinal microbiota even while on a gluten-free diet. This fact could favor the pathological process of the disorder. The concentration of bifidobacteria per gram of feces was significantly higher in healthy subjects (2.5 ± 1.5 x107 CFU/g) when compared to celiac patients (1.5 ± 0.63 x108 CFU/g).6

  • Relationship between active celiac disease and endoscopy technique. The most severe degree of villous atrophy was detected when distal duodenal biopsy specimens were taken in addition to a duodenal bulb biopsy specimen from either the 9- or 12-o’clock position (96.4% sensitivity; 95% CI, 79.7%-100%). The difference between the 12-o’clock position biopsy and the 3-o’clock position biopsy in detecting the most severe villous atrophy was 92% (24/26 patients) versus 65% (17/26 patients).7
  • Relationship between active celiac disease and diet adherence. Patients with consistent gluten free diet adherence experience symptomatic responses to dietary gluten (SRDG) faster and more severe in comparison to their prior gluten exposure possibly demonstrating an adept immunological response. Anxiety and depression also enhance the speed of symptom onset and co-existing visceral hypersensitivity is a risk factor for severe reactions to dietary gluten.8
  • Relationship between active celiac disease and atrial fibrillation: Patients with celiac disease, verified by intestinal biopsy, are at increased risk of atrial fibrillation. This observation is consistent with previous findings that elevation of inflammatory markers predicts atrial fibrillation.9

How Prevalent Is Gluten Sensitive Enteropathy?

Sources:
  1. Murray JA, the widening spectrum of celiac disease. American Journal of Clinical Nutrition. Mar 1999; 69(3):354-365. [↩]
  2. Murray JA, the widening spectrum of celiac disease. American Journal of Clinical Nutrition. Mar 1999; 69(3):354-365. [↩]
  3. Johnston SD, Smye M, Watson RGP. Intestinal permeability and morphometric recovery in coeliac disease. Lancet. Jul 28, 2001;358(9278):259, 2p. [↩]
  4. Rauhavirta T, Lindfors K, Koskinen O, Laurila K, Kurppa K, Saavalainen P, Mäki M, Collin P, Kaukinen K. Impaired epithelial integrity in the duodenal mucosa in early stages of celiac disease. Transl Res. 2014 Sep;164(3):223-31. doi: 10.1016/j.trsl.2014.02.006 [↩]
  5. Stazi AV, Trinti B. Selenium status and over-expression of interleukin-15 in celiac disease and autoimmune thyroid diseases. Ann Ist Super Sanita. 2010;46(4):389-99.DOI: 10.4415/ANN_10_04_06. [↩]
  6. Golfetto L, de Senna FD, Hermes J, Beserra BT, França Fda S, Martinello F. Lower bifidobacteria counts in adult patients with celiac disease on a gluten-free diet. Arq Gastroenterol. 2014 Apr-Jun;51(2):139-43. [↩]
  7. Kurien M, Evans KE, Hopper AD, Hale MF, Cross SS, Sanders DS. Duodenal bulb biopsies for diagnosing adult celiac disease: is there an optimal biopsy site? Gastrointest Endosc. 2012 Jun;75(6):1190-6. doi: 10.1016/j.gie.2012.02.025. [↩]
  8. Barratt SM, Leeds JS, Sanders DS. Factors influencing the type, timing and severity of symptomatic responses to dietary gluten in patients with biopsy-proven coeliac disease. J Gastrointestin Liver Dis. 2013 Dec;22(4):391-6. [↩]
  9. Emilsson L, Smith JG, West J, Melander O, Ludvigsson JF. Increased risk of atrial fibrillation in patients with coeliac disease: a nationwide cohort study. Eur Heart J. 2011 Oct;32(19):2430-7. doi: 10.1093/eurheartj/ehr167. [↩]

Arthritis, Juvenile Idiopathic

Rheumatoid_arthritis_joint[1]What Is Juvenile Idiopathic Arthritis?

[dropcap]J[/dropcap]uvenile idiopathic arthritis (JIA) is a rheumatic disorder characterized by chronic, inflammatory disease of large and small synovial joints and other organs in children under age 16 years. Growth and development may be impaired in these children.1

Q: Which joints are affected in juvenile idiopathic arthritis?

A: In juvenile idiopathic arthritis the joints that are affected are variable and so are the manifestations.

According to the International League of Associations for Rheumatology (ILAR) classification system, there are seven different subtypes of  juvenile idiopathic arthritis. 

The main treatment to reduce inflammation and relieve pain is with non-steroidal inflammatories such as Ibuprofen.

What Is Juvenile Idiopathic Arthritis In Celiac Disease and/or Gluten Sensitivity?

Sources:
  1. Stagi S, Giani T, Simonini G, Falcini F. Thyroid function, autoimmune thyroiditis and coeliac disease in juvenile idiopathic arthritis. Rheumatology. Apr 2005;44(4):517-20. [↩]

Food Allergy – IgE and Non IgE

Baby with Allergic Reaction to Peanuts. GFW
Baby with Allergic Reaction to Peanuts. GFW photo.

What Is Food Allergy?

[dropcap]F[/dropcap]ood allergy is an abnormal immune response to food proteins that may damage the small intestinal  lining and produce malabsorption of food. The reaction is usually delayed which makes it difficult to identify the offending food that is causing symptoms.

Q: How does food allergy develop?

A: The gastrointestinal tract serves not only to digest and absorb foodstuffs but also to protect the body from unwanted substances. When allergic food substances are eaten, the immune response that is triggered in the gut produces inflammation with symptoms such as pain, vomiting and loose bowels.

Inflammation causes swelling of the gut lining that can interfere with the passage of nutrients through it to the body which results in malabsorption. Malabsorption deprives the body of nutrients needed for normal function.

Symptoms other than digestive may involve skin rashes, hives, and respiratory difficulties that can be distressing and life-threatening.

What Is Food Allergy In Celiac Disease and/or Gluten Sensitivity?

Anti-Gliadin Antibodies Present

This is a model of Immunoglobulin-G Antibody (IgG)
This is a model of Immunoglobulin-G Antibody (IgG)

What Are Anti-Gliadin Antibodies?

[dropcap]A[/dropcap]nti-gliadin antibodies (AGA) are produced by the body as an immune response against partially digested gliadin peptides (fragments) that have abnormally entered the body from the intestinal tract. Gliadin is a protein in wheat grain.

Anti-gliadin antibodies circulating in blood are measured by laboratory testing on blood that is drawn. The antibodies are both immunoglobulin A (IgA) and immunoglobulin G (IgG) types, which are termed AGA-IgA and AGA-IgG.

The presence of anti-gliadin antibodies in blood is an abnormal laboratory finding. That is, when the intestinal lining is healthy and able to keep out undigested matter from the body, there are no molecules of gliadin present to trigger the immune system for defense.

Q: Who produces anti-gliadin antibodies?

A: Persons, with or without celiac disease, can produce anti-gliadin antibodies if and when leaky gut (increased intestinal permeability) develops that then allow gliadin peptides to get into the bloodstream.

Gliadin itself causes leaky gut, but there are other causes such as various foods, intestinal infections, medications, and other diseases of the gastrointestinal tract. Whatever the cause of leaky gut, if poorly digested gliadin is present, it can slip through the leaky lining and enter the bloodstream where it can trigger an antibody response by anti-gliadin antibodies.

What Are Anti-Gliadin Antibodies In Celiac Disease and/or Gluten Sensitivity Or Non-Celiac Gluten Sensitivity?