Study reveals the complex interplay of immune dysfunction, gut health, and immunosuppressants in the rise of food allergies among young organ transplant recipients.
Study: Transplant-Acquired Food Allergy in Children. Image Credit: Ground Picture / Shutterstock.com
In a recent study published in the journal Nutrients, researchers review the phenomenon of transplant-acquired food allergies, which commonly occur in pediatric transplant recipients within one year after the organ transplantation.
What causes food allergies?
The prevalence of food allergies is increasing worldwide, especially in developed countries where up to 10% of the population is estimated to be affected by this condition. Food allergies, which arise due to a heightened immune response to certain foods, can lead to a wide range of symptoms, from mild skin reactions to severe life-threatening anaphylaxis.
Transplant-acquired food allergies typically affect children who have undergone organ transplantation to manage end-state organ failure, cancer, or autoimmune diseases. Epidemiological studies indicate that food allergies often occur in children who have undergone liver transplantation. However, these allergies have also been reported in children who have received heart, lung, cord blood, kidney, or intestine transplants.
The foods that are most commonly associated with transplant-acquired allergies include eggs, soy, wheat, and peanuts. In 69% of cases, these allergies subside with increasing age.
Liver transplant-related food allergy hypothesis
Some evidence suggests that liver transplantation leads to dysfunction, which may contribute to the loss of acquired food tolerance. Reduced food tolerance can lead to the reemergence of pre-existing food allergies or the onset of new allergies after transplantation.
Certain hepatic mechanisms have been linked to the establishment of immune tolerance to food antigens. These mechanisms explain the gradual acquisition of tolerance years after liver transplantation in children with transplant-acquired food allergies due to the restoration of liver function.
For example, a high abundance of pluripotent hematopoietic stem cells (HSCs) and resident dendritic cells in the liver may facilitate gradual sensitization to allergens over time in children with food allergies following liver transplantation. Passive transfer of allergen-specific immunoglobulin E (IgE) antibodies and T lymphocytes from already sensitized donors may also contribute to the acquisition of food tolerance in children who have received an organ transplant.
Immunosuppressive agent-related food allergy hypothesis
Immunosuppressive agents like tacrolimus and cyclosporine A are commonly used to prevent organ rejection by the patient's immune system. These agents reduce the recipient's immune functioning and subsequently increase their risk of developing allergies.
Evidence indicates immunosuppressive agents increase intestinal permeability and cause imbalanced type-2 helper T cell (Th2) responses. Increased IgE antibody production can trigger food allergic reactions and eosinophilic inflammation.
Microbiota-related food allergy hypothesis
Gut microbiota has a vital role in developing and preventing food allergies. Gut microbiota dysbiosis, which refers to an imbalance in microorganism populations within the gastrointestinal tract, has been observed in children with IgE-mediated cow milk allergies.
Liver transplantation has been identified as a major cause of gut microbiota dysbiosis. In fact, several studies have observed an imbalance in bacterial flora in patients who have previously undergone liver transplantation that is characterized by an increased abundance of harmful bacteria and a reduced abundance of beneficial bacteria.
Review findings
The current studystudy'sors conducted a literature search on the PubMed database for studies published between June and July 2024. A total of 36 studies were identified, 24 of which were retrospective studies, one prospective study, two cross-sectional studies, and nine case reports or series.
All selected studies involved pediatric populations with different types of organ transplantations, 33, six, and three of which included liver, kidney, and heart transplant patients, respectively. Two studies individually assessed the effects of bone marrow and cord blood transplantation on the risk of newly acquired food allergies, respectively, and three additional studies included bowel transplant recipients.
Among immunosuppressive agents, tacrolimus was the most commonly used, followed by cyclosporine, mycophenolate mofetil, sirolimus, and azathioprine.
The prevalence of transplant-acquired food allergies in the selected studies ranged from 3.3% to 54.3%. In addition to food allergies, several studies also reported the development of atopic dermatitis, asthma, and rhinitis in transplant recipients.
The most common food allergies in transplant recipients included milk, eggs, fish, nuts, soy, wheat, and shellfish. Other reported allergens were fruits, sesame, potatoes, lentils, pork, chicken, beef, horse, and lamb.
Both IgE- and non-IgE-mediated food allergies were reported by the selected studies. However, none of the studies identified a significant association between IgE levels and allergy severity.
Removal of the allergic foods and administration of adrenaline were the treatment strategies used in all studies.
Most studies reported that food allergies appeared between one and two years after the organ transplant, with few studies reporting the early emergence of allergies within one year of transplantation.
Significance
The current study provides a detailed overview of transplant-acquired food allergies. Consistent immunological monitoring remains urgent for the early detection and effective management of food allergies in pediatric transplant recipients.
Journal reference:
- Indolfi, C., Klain, A. Dinardo, G., et al. (2024). Transplant-Acquired Food Allergy in Children. Nutrients. doi:10.3390/nu16183201