Breaking News
April 22, 2019 - Hyaline fibromatosis syndrome – Genetics Home Reference
April 22, 2019 - Scientists use CRISPR for possible ‘bubble boy’ therapy
April 22, 2019 - Hematologist (and a mom, singer, actress and much more) stands up for diversity
April 22, 2019 - Novel AI voice tool can help diagnose PTSD
April 22, 2019 - Overlooked part of cell’s internal machinery may hold key to treating acute myeloid leukemia
April 22, 2019 - MIT scientists reverse some behavioral symptoms of rare neurodevelopmental disorder
April 22, 2019 - Scientists find new therapy target for drug-induced liver failure
April 22, 2019 - Opioid dose variability could lead to increased risk of overdose, study suggests
April 22, 2019 - Newly developed model predicts salmonella outbreaks several months in advance
April 22, 2019 - Deep-learning model better predicts survival outcomes for lung cancer
April 22, 2019 - One in Three U.S. Adults Aged 35 to 44 May Have Drinking Problem
April 22, 2019 - Why the measles virus is so contagious
April 22, 2019 - Magnet ‘Zap’ to the Brain Might Jumpstart Aging Memory
April 22, 2019 - Immune response to gut microbes may be early indicator of type 1 diabetes
April 22, 2019 - Destination Limbo: Health Suffers Among Asylum Seekers In Crowded Border Shelter
April 22, 2019 - Research shows how dopamine contributes to sex differences in worms
April 22, 2019 - Marijuana users weigh less compared to non-users
April 22, 2019 - Research uncovers critical RNA processing aberrations in ALS and FTD
April 22, 2019 - Many cancer patients use marijuana and prescription opioids, study reveals
April 22, 2019 - Frailty may up fracture risk in patients with type 2 diabetes
April 22, 2019 - Study provides new insight into how obesity, insulin resistance can affect cognition
April 22, 2019 - Study seeks to better understand the genetic causes for hypospadias
April 22, 2019 - FDA grants approval of first generic naloxone nasal spray to treat opioid overdose
April 22, 2019 - FDA authorizes marketing of first medical device to treat ADHD
April 22, 2019 - Vanderbilt researchers to develop and test ‘safe harbor’ standards of care
April 22, 2019 - You’re probably brushing your teeth wrong – here are four tips for better dental health
April 22, 2019 - Pharmacy closures contribute to medication non-adherence among heart patients
April 22, 2019 - Using Edge AI technology to observe behavior of cattle
April 22, 2019 - Bacteria play a role in the development of stomach ulcers in pigs
April 22, 2019 - Hand Hygiene Compliance Poor in Task Transitions
April 22, 2019 - smoking could harm your baby
April 22, 2019 - Scientists identify rare, paradoxical response to antiretroviral therapy
April 21, 2019 - More TV, Tablets, More Attention Issues at Age 5
April 21, 2019 - Drug reduces risk of kidney failure in people with diabetes, study finds
April 21, 2019 - New research identifies novel link between antibiotic resistance and climate change
April 21, 2019 - Simple intervention can provide lasting protection for teens against junk food marketing
April 21, 2019 - The protein p38-gamma identified as a new therapeutic target in liver cancer
April 21, 2019 - Novel system enables researchers to study bacteria within mini-tissues in a dish
April 21, 2019 - Discovery of oral cancer biomarkers could save thousands of lives
April 21, 2019 - Geneva Exhibition committee gives gold medals to two medications developed by Kazan
April 21, 2019 - Scientists aim to minimize or eliminate hair loss during cancer treatment
April 21, 2019 - WiFi interacts with signaling pathways in the human brain
April 21, 2019 - Stroke Hospitalizations Down in Black, White Medicare Enrollees
April 21, 2019 - First common risk genes discovered for autism
April 21, 2019 - Researchers map auditory sensory system of the mouse brain
April 21, 2019 - Scientists Bring Pig’s Brain, Dead 4 Hours, Back to ‘Cellular Activity’
April 21, 2019 - Virtual reality a promising tool for reducing fears and phobia in autism
April 21, 2019 - New analysis lists out opportunities for U.S. medical schools to advance population health
April 21, 2019 - More sleep may help teens with ADHD focus and organize
April 21, 2019 - Breakthrough antibody treatment suppresses HIV without antivirals
April 21, 2019 - AveXis Data Reinforce Effectiveness of Zolgensma in Treating Spinal Muscular Atrophy (SMA) Type 1
April 21, 2019 - Is your hand pain arthritis, carpal tunnel or something else?
April 21, 2019 - Measles outbreaks may become more frequent if vaccination rates continue to decline
April 21, 2019 - Researchers succeed in accelerating process of creating 3D images
April 21, 2019 - Tiny worm mimics key genetic risk for Alzheimer’s
April 21, 2019 - Angry dreams explained by brain waves
April 20, 2019 - Parenteral Antimicrobial Tx at Home Burdens Children’s Caregivers
April 20, 2019 - Diabetes treatment may keep dementia, Alzheimer’s at bay
April 20, 2019 - New bandage-like biosensor collects and analyzes sweat
April 20, 2019 - A comprehensive, centralized database of bovine milk compounds
April 20, 2019 - Two new epigenetic regulators maintain self-renewal of embryonic stem cells
April 20, 2019 - New Evidence That Veggies Beat Steak for Heart Health
April 20, 2019 - Study reveals genes associated with heavy drinking and alcoholism
April 20, 2019 - Texas A&M AgriLife becomes the newest member of NutriRECS international consortium
April 20, 2019 - In most states, insurance won’t cover addiction treatments
April 20, 2019 - Computer-based memory games may be beneficial for individuals with fragile X syndrome
April 20, 2019 - Timing of food intake influences molecular clock in the liver of mice
April 20, 2019 - Precise decoding of breast cancer cells paves way for new treatment option
April 20, 2019 - Scientists use 3D imaging to help model complex processes performed by placenta
April 20, 2019 - MediciNova Announces Plans to Move Forward with a Phase 3 Trial of MN-166 (ibudilast) in ALS
April 20, 2019 - Genetic variants that protect against obesity could aid new weight loss medicines
April 20, 2019 - New technology developed for microscopic imaging in living organisms
April 20, 2019 - when quitting cigarettes, consider using more nicotine, not less
April 20, 2019 - Key proteins can block Listeria without triggering the death of host cells
April 20, 2019 - Researchers create a working model of cerebral tract to study brain function
April 20, 2019 - New study shows that microbes can help break toxic chemical in dust
April 20, 2019 - Scientists use NIR light and injected DNA nanodevice to guide stem cells to injury
April 20, 2019 - Microbial Features ID’d for Pediatric Irritable Bowel Syndrome
April 20, 2019 - Study reveals patterns of drug intoxication deaths, organ donors across the US
April 20, 2019 - Scientists deploy CRISPR gene-editing tool to engineer multiple edits
Shellfish allergies: can they be treated?

Shellfish allergies: can they be treated?

image_pdfDownload PDFimage_print
Shellfish allergies: can they be treated?
Shrimp cocktail: Tasty to some, potentially deadly for others. Credit: Legoktm/Wikimedia

Seafood platters? Bouillabaisse? Arroz de Marisco? Seafood paella? Oysters Rockefeller? Lobster Thermidor? Dining out with friends, a romantic meal, celebrating Christmas or a holiday on a wind-swept coast with these seafood dishes on your table are enjoyable moments.

But have any of you, your friends or family experienced swelling of lips or eyelids, itchiness and rashes developed over your face or body, or even difficulty in breathing just a few minutes after eating shrimp, lobster, crab, clam, mussels, oysters or scallops? If yes, you could well have a shellfish allergy.

What is shellfish allergy?

Shellfish allergy is a type of hyper-immune response mediated by Immunoglobulin E (IgE), an antibody produced by B cells.

When someone who is allergic eats some shellfish, the allergens – primary tropomyosin, a muscle protein – bind with IgE. This allergen-IgE complex then cross-links on mast cells. These cells play a key role in the inflammatory process, by which they contain many granules rich in inflammatory mediators like histamine. Histamine can increase the permeability of the blood capillaries, exert effects on mucous glands and bronchila tubes, and is a central mediator of allergic reactions like itching.

A lifelong condition

As designated by the United States Food Allergen Labelling and Consumer Protection Act, crustacean shellfish are one of the top eight allergens alongside with milk, eggs, peanuts, tree nuts, wheat, soybeans and fish accounting for 90% of food-related allergic reactions.

Skin prick tests are usually efficient to determine allergies but also present several shortcomings. Credit: Imperial College London

Unlike allergies to egg and cow’s milk for which children often gradually acquire natural tolerance, shellfish allergies usually persist throughout life.

Shellfish is the leading offending food in the United States, Canada, Portugal, and in the Asia-Pacific regions, including Hong Kong and Taiwan. A multi-centre survey conducted in Europe, on the other hand, reported 4.8% of adults with IgE sensitisation to shrimp and in some areas like Zurich, the sensitisation rate can be up to 7%.

Poor diagnosis

Despite such a high impact, diagnosis and treatment of shellfish allergy remains suboptimal. The standard clinical diagnostic involves a thorough review of a patient’s clinical history followed by skin prick test (SPT) and measurement of shellfish-specific IgE level. A SPT reaction spot that is 3mm or more in diameter and an IgE level of greater than or equal to 0.35 kUA/L which stands for kilo unit of allergen-specific IgE per litre, are commonly defined as a positive diagnosis of a shellfish allergy.

However, the rapidly growing number of diagnoses have highlighted concerning the shortcomings of these conventional procedures. SPT and IgE measurement with shellfish extract have low specificity of only 50%, meaning that 50% of people with a positive result in these tests may never experience clinical symptoms of shellfish allergy.

Although reactions to all sorts of shellfish is common, reports have suggested species-specific allergic reactions – for example, you may be able to eat one species of prawn even if you are allergic to another. However, because tests cannot identify cross-reactivity, patients are often suggested to avoid all types of shellfish if they have allergic reactions to one type of shellfish.

Shellfish allergies: can they be treated?
If you’re allergic to mussels, you might not be allergic to clams. Tracking shellfish allergies need to take into consideration species-specific allergic reactions. Credit: Pxhere, CC BY

The oral food challenge, a test that involve giving increasing amounts of a food to a patient to determine if he or she has a food allergy, remains the gold standard. But it is resource-intensive, time-consuming, costly and risky. Subjects’ reluctance due to a fear of side effects preclude the implementation of this procedure in clinical settings.

Treatment could be improved

“Active” treatment options that would desensitize shellfish-allergic patients are unfortunately not yet available. Patients are recommended to avoid shellfish that trigger symptoms, educated to read food labels to avoid accidental consumption, take antihistamines to alleviate mild symptoms, and use epinephrine auto-injector – a hand-held device that delivers epinephrine to relax the airways by intramuscular injection – in case of an anaphylactic reaction. However, none of these first-line measures cures the disease.

Food desensitisation and tolerance induction could be achieved by “re-educating” the immune system through giving small doses of the offending food and increasing it over time. However, existing interventions have reservations and limitations: the efficacy in developing tolerance is debatable; the adherence of patients is poor as the treatment is lengthy (2 to 5 years to “complete”); there are risks such as developing allergic side effects; and they’re costly, running between US$800 and $1,000 per year.

Our research team therefore focused our effort to address these shortcomings through investigating the value of peptide-based oral immunotherapy, by which these peptides are short fragments of tropomyosin with molecular nature of modifying the immune system, and also by constructing hypoallergens of shrimp tropomyosin and hypoallergen-based vaccines. Hypoallergens are modified from tropomyosin to be less than normally allergenic.

Dr.Wai explaining her hypoallergene-DNA vaccine project.

Using a small DNA molecule to counter the allergy

With the lower IgE reactivity, hypoallergens are of lower risk in triggering allergic reactions. We also adopted the concept of DNA vaccination – the injection the DNA sequence of the hypoallergen in a small circular piece of bacterial DNA.

When taken up by body cells, this piece of circular DNA is used by the cells’ machinery to produce the hypoallergen protein. Because these proteins are regarded as foreign, the immune system is alerted to trigger immune response. The continual production of the hypoallergen protein by the vaccine and body cells therefore “educates” the immune system as in the conventional immunotherapy but achieved with fewer shots.

This combinatorial approach offers the advantages of improved vaccine stability, relative ease of large-scale manufacture, reduced shots and treatment duration, and thus a lower cost of immunotherapy.

From our animal experiments three shots of this hypoallergen-DNA vaccine resulted in the decrease of IgE level by 70%, accompanied by the increase in the number and activity of immune cells with regulatory functions. This suggests that this vaccine may be a valuable treatment for inducing immune tolerance against shellfish allergy achievable with much fewer injections and within shorter time period.

However, the only FDA-approved plasmid, pVAX1, has limited immunogenicity in human, meaning that DNA vaccines constructed using pVAX1 has limited capacity in provoking immune responses in the body of a human.

Engineering next-generation vaccines with optimised plasmids and studying their effects and mechanism would be our next steps, and we hope to provide a promising option in the future. Until then, be cautious with that lobster.

One in ten adults in US has food allergy, but nearly one in five think they do

Provided by
The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.The Conversation

Shellfish allergies: can they be treated? (2019, March 12)
retrieved 22 March 2019

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

Tagged with:

About author

Related Articles