An Allergy-Immunology View of GI Diseases

Recently, one of our allergy-immunology colleagues, Dr. Kiran Patel, from Emory presented an update on GI Diseases from an allergist viewpoint at one of our GI clinical education meetings. With his permission, many of the slides are noted below.  The slides present a good deal of information, though a lot of nuance and further details were provided by Dr. Patel.

Next few slides discuss typical GI food allergies.  It is not surprising that a lot of allergies manifest with GI symptoms given the amount of immune cells in the intestines and frequent interactions with foods and antigens.

This next slide points out that four of the most common food allergens (cow’s milk, egg, soy, and wheat) are frequently outgrown, whereas with peanuts, tree nuts, fish, and shellfish, it is uncommon to outgrow these allergies..

The next slide discusses potential evaluation.  While the slide states that the positive predictive value of skin prick tests and serum-based IgE tests may be as high as 50%; in fact, when broad panels of allergy tests are ordered, the positive predictive value can be quite low.

Related blog posts:

Dr. Patel did discuss the LEAP study and the LEAP-ON study which overall indicate that early antigen introduction is likely to reduce food allergies. Related blog posts:

 

The next few slides review Food Protein-Induced Enterocolitis Syndrome. Related blog posts:

The next few slides discuss eosinophilic esophagitis (EoE).  Allergy testing has not been very helpful in most patients with EoE. Related blog posts:

The last part of Dr. Patel’s talk focused on GI disease (eg. inflammatory bowel disease presentation) of primary immune deficiencies.  In the bottom slide, the diseases that often present with GI symptoms are boxed.

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications (along with potential adverse effects) and changes in diet should be confirmed by prescribing physician.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

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Tick Bites Can Lead to Allergy to Red Meat

From NBC News: Tick Bite Linked to Rise in Red Meat Allergies

Excerpt:

A tick-related meat allergy has been quietly spreading across the southern and eastern U.S. over the past two decades, but in recent years the number of cases have steadily risen. A tick bite in some people can kick off a sensitivity to red meat that can result in symptoms such as itching, hives, swollen lips and breathing problems. The reaction can sometimes be life threatening. 

Terrific 8th grade graduation speech: 8th grader Nails Impersonations of presidential candidates

Eosinophilic Esophagitis Review -NEJM

Good review:  Glenn T. Furuta, M.D., and David A. Katzka, M.D. N Engl J Med 2015; 373:1640-1648

A couple pointers from this review:

  • Estimated prevalence of eosinophilic esophagitis (EoE) 0.4% in Western countries.  Symptoms are often underestimated due to patient ‘accommodation’ which includes eating slowly/carefully, drinking a lot of liquids and avoiding items more prone to become lodged (meats, pills, breads)
  • Pathogenesis: “Birth by cesarean section, premature delivery, antibiotic exposure during infancy, food allergy, lack of breast-feeding, and living in an area of lower population density have all been associated with eosinophilic esophagitis.”
  • Impaired barrier function and enhanced the activity play a role in pathogenesis
  • Food allergy is a non-IgE-mediated process.  Omalizumab, an anti-IgE biologic, is ineffective in EoE and EoE can develop in IgE-null mice
  • Male predominance (3:1) suggests that there is a genetic component.
Esophagus with ringed appearance, furrowing, and loss of vascular markings

Esophagus with ringed appearance, furrowing, and loss of vascular markings

Another useful reference on Eosinophilic Gastritis in Children: Am J Gastroenterol 2014; 109; 1277-85.  This article provides data on clinical and histologic remission with eosinophilic gastritis (>70 eos/hpf), n=30 children.  “Response to dietary restriction was high” (82% clinical, 78% histologic response) Thanks to Seth Marcus for this reference.

Related blog posts:

What’s Wrong with “I Want My Kid Tested For Food Allergies”

Most parents, and many physicians, do not understand the limitations of food allergy testing.  As I am sure is common among physicians, I frequently receive requests for food allergy testing; parents do not realize that the strategy for food allergy testing is not straight-forward and has not advanced significantly for decades.  This information is detailed in a recent study and associated editorial (J Pediatr 2015; 166: 97-100, editorial 8-10: “Pitfalls in Food Allergy”).

The study was a retrospective review of all new patients seen at a pediatric food allergy center (2011-2012).  This involved a review of 797 new patients.

Key findings:

  • Of 284 patients who had received a food allergy panel, only 90 (32.8%) had a history warranting evaluation for food allergy.
  • Among 126 individuals who had food restrictions imposed based on food allergy panel testing, 112 (88.9%) were able to re-introduce at least 1 food into their diet.
  • The positive predictive value of food allergy testing was 2.2%.

So what can we learn from this study and editorial?

Misdiagnosis often relates to a lack of understanding regarding serum IgE-based testing.  First of all, many children with atopic dermatitis (and other atopic conditions) have elevated total IgE which results in more false positives.  In addition, a positive IgE test for a specific food indicates sensitization but not necessarily an allergy.

Strategy for testing (recommended by editorial):

  • “The key to the diagnosis of food allergy cannot be overstated; it begins with a detailed clinical history”
  • Testing should be “limited in general to the food(s) in question.”
  • When there is uncertainty, oral food challenges can be performed by specialists.
  • “If a patient is consuming a food without clinical symptoms of allergy, allergy testing should not be done to that food.”

Bottomline (from authors’ conclusion): “Food allergy panel testing often results in misdiagnosis of food allergy, overly restrictive dietary avoidance, and an unnecessary economic burden on the health system.”

Related blog posts:

 

Family Feud with Allergies and Celiac Disease

A recent article in Allergic Living highlights the common phenomenon of other family members not believing or not willing to make changes in the face of food allergies and celiac disease.

Here’s an excerpt:

Every day, adults and kids are diagnosed with food allergies or celiac disease, and they naturally expect that the people closest to them will take the most care – as they would with any serious health condition. After all, you should be able to trust your mom to keep gluten out of her gravy, and assume that, when your brother babysits your peanut-allergic daughter, he carefully reads the ingredients on that chocolate bar, right?

For too many living with food allergies and celiac disease, sadly the answer is no. In the fall of 2010, Allergic Living sent out a request for anecdotes of family experiences (both good and bad), and within days we were inundated with responses…

In the end, there is no magic cure that will work for every family because complex problems cannot be solved with simple solutions – and, as they say, you don’t choose your family. But clear and calm communication is vital, as is the ability for those living with allergies to put themselves in their relatives’ shoes.

Related blog post:

Save a life with free allergy education | gutsandgrowth

Comparing diets in EoE

There remains a limited number of therapeutic options with EoE.  Dietary therapy can be effective as well as burdensome.  A closer look at dietary treatment effectiveness was recently published (J Allergy Clin Immunol 2012; 129: 1570-8 –thanks to Seth Marcus for alerting me to this article).

Due to eligibility requirements, only 98 patients of an initial 513 met criteria.  The findings from this study may be difficult to generalize because of the following:

  • Highly selected patient population
  • Retrospective study.   Dietary therapy was NOT chosen randomly.
  • Study originates from a specialized center (Cincinnati) which attracts atypical cases of EoE

That being said, the study asks some important questions. What is the remission rate for skin test-directed elimination diet in comparison to six food group elimination diet (SFED) and to an elemental diet?  The SFED actually composed two groups (in my opinion, this is a significant flaw in the study design & has a limiting effect on the conclusions).  The ‘classical’ SFED (42% or 11/26) eliminated the six most common food groups (milk, soy, wheat, egg, nuts, fish/shellfish) whereas a ‘modified’ SFED (58% or 15/26)  combined the classical SFED with foods eliciting positive skin-testing.

Some of the authors terminology:

  • Complete remission: 1 or fewer eosinophils/hpf
  • Partial remission: 2-5 eos/hpf
  • Partial resolution: 6-14 eos/hpf
  • Remission: <15 eos/hpf
  • Non-remission: >15 eos/hpf

Skin prick tests (SPFs) were performed to as many as 62 foods and 11 environmental allergens and graded 0-4.  0 equated to negative control & 4 equated to histamine control -all interpreted at 15 minutes after placement.

Atopy patch tests (APTs) were interpreted at 48 hours with scoring between 0-4.  A score of 2 indicated “erythematous with generalized induration.”  Any score of 2 or higher was considered positive.

Food reintroduction process: “Food reintroductions were initiated only when the peak eosinophil count was less than 15 eosinophils/hpf. If symptoms occurred after reintroduction of a food, patients were instructed to discontinue that food, wait approximately 10 to 14 days, and then reintroduce another food…. A food reintroduction was considered successful if no symptoms were reported and the postpeak eosinophil count was less than 15 eosinophils/hpf.”

Why were so many patients excluded?  The main causes were 181 patients did not meet strict EoE criteria, 122 patients received glucocorticoids, and 52 patients had another eosinophilia-associated condition; less common reasons included patient age >21, being part of a separate drug trial, obvious noncompliance, different diet regimen, and not having 2 consecutive EGDs separated by dietary intervention.

How many endoscopies are needed for dietary therapy?   In this study, the average patient had 8.5 EGDs at Cincinnati.  The greatest number of EGDs took place among patients assigned to an elemental diet (average >11); these patients also had a longer followup period compared to the other two groups: 2.9 years compared with 1.1 for SFED and 2.1 for directed diet.

  • All three diets resulted in improvement in eosinophil count.
  • Overall Remission rates: 96% elemental, 81% SFED, 65% directed diet
  • Complete Remission rates:  59% elemental, 39% SFED, 30% directed diet

One interesting set of data is in Table 4.  This gives the pass rate for various foods with single and multiple food reintroductions.  Milk for example had a pass rate of 35% among the 17 patients who had this as a single food reintroduction.  The values ranged from a low pass rate of 29% for strawberries to a high pass rate of 78% for cocoa and 75% for pork. Soy, eggs, and wheat all hovered near 60% pass rate.

Conclusions by authors:

1. “SFED is no less successful than directed diet and consistent with unreliability of skin testing …Our data…undermine the value of skin test-directed dietary management. ” This is due to the fact that the disease mechanism is not an IgE-mediated disease (skin testing primarily detects IgE-mediated allergens).

2. Elemental diet is superior at inducing histologic remission. However, “multiple studies indicate that adherence is inversely related to the number of foods eliminated.”

Previous related posts:

Guidelines for Eosinophilic Esophagitis

Looking better or feeling better in EoE?

Look of improvement on an EoE diet

Eosinophilic Esophagitis -Six Food Group Diet

MicroRNA signature for eosinophilic esophagitis

The undiscovered country

 

Save a life with free allergy education

Food allergy affects 4-8% of children and allergic reactions can be fatal.  In fact, the main cause of poor outcome with accidental food allergy exposure is delay in the use of epinephrine.  To improve parental knowledge and overall management of food allergies, a group of allergists, nurses and dieticians has developed and validated educational materials (J Pediatr 2012; 160: 651-6).  In addition, they have made these materials available at no cost online:

To validate their materials, the authors enrolled 60 parents of newly referred children with a prior food allergy.  The measured outcome was demonstration of an autoinjector for epinephrine.  The correct number of steps in the use of the autoinjector increased from a 3.4 to 5.95 score (max score 6).  In addition, at 1 year, the score remained high, 5.47.  Knowledge tests improved as well: from 9.2 to 12.4 (out of 15); at one year, the score was 12.7.  On a practical basis, the frequency of allergic reactions was reduced as well.  The annualized allergic reaction rate dropped from 1.77 (historical data) to 0.42 after the instruction.

The article also relates that some of the material relied on previous educational material, in particular the food allergy emergency plan available from the Food Allergy & Anaphylaxis Network (www.foodallergy.org).

Materials available include information on specific allergic disorders, avoiding allergens, management in and outside home, and living a safe/healthy life.  In addition, an educational video is available.

Additional references:

  • -Bock SA et al. J Allergy Clin Immunol 2007; 119: 1016-8. Poor outcome with accidental food allergy exposure is delay in the use of epinephrine.
  • -J Pediatr 2011; 158: 578.  Oral food challenges allowed 84% to return foods to diet.  n=125.
  • -Clin Gastro & Hep 2010; 8: 755.  Review of food allergy (vs intolerance) in adults.  Gives list of hypoallergenic diet , pg 758.
  • -Pediatrics 2009; 124: 1549-55.  3.9% of US kids w food allergy.  Nat’l surveys.
  • -NEJM 2008; 359: 1252 Review. Usual age of resolution: eggs  @ 7yr (75%), milk @ 5yr (76%); wheat/soy -rarely cause IgE-mediated allergies 80% resolve by 5yrs>  More  persistent allergens:  peanuts/tree nuts/sesame seeds = persistent in 80-90% at 5yrs, fish = persistent.
  • -Pediatrics 2003; 111: 1591-1680.  (supplement) Pediatric Good Allergy symposium
  • -Pediatrics 2003; 111:829-835. Infants c food-induced enterocolitis often have multiple food allergies (cereal, veggie, poultry, meat)  IgE based tests are negative (skin prick & IgE Abs
  • -Gastroenterology 2001; 120: 1023-25; 1026-40.  AGA position paper; technical review.
  • -J Allergy Clin Immmunol 1999; 103: 717-728 &981-9.  Pathogenesis &  Dx/ mgt.