Discovery of Immune Cells That Lower Airway Allergy and Asthma Attacks

By: Khushi Sheth

Image Credit: Flickr @ AJC1

Our atmosphere is full of dust particles. If you clean your house or even just open the blinds, you’ll see thousands of dust mites floating around. Most people’s bodies have the tendency to react negatively to an excess amount of dust particles in the air. While most bodies’ immune cells usually have the capability of reacting to these allergens, some people are allergic to dust and can display typical allergy symptoms like sneezing, runny nose, cough, and swollen nasal pathways. People with asthma usually have a more severe reaction to these allergies.

Asthma is a chronic respiratory disease. People with asthma naturally have a thinner nasal pathway. An asthma attack occurs when the airways are inflamed, resulting in swelling and decreased airflow to the lungs. Cells in the airway can also produce a large amount of mucus that contributes to asthma’s characteristic shortness of breath by obstructing gas exchange.


Researchers at La Jolla Institute for Immunology in La Jolla, California discovered an unknown subset of T cells [refer to Educational Content Question 1 for more context on T-cells] in non-allergic people that may be responsible for controlling the body’s immune response to allergens. The study built on the idea behind linking gene expression to disease development. The researchers in this study used the Immune Epitope Database that houses information to research how the immune system reacts to allergens. One of the main allergens researched was house dust mites since they were found everywhere. Because everyone is exposed to dust mites, there is a guarantee that there will be an immune response, either positive or negative, that can be tracked in the database.


One of the techniques found in the database includes a single-cell RNA sequence that shows the specific genes and molecules that T cells produce in response to dust mite allergens. In the experiment, the researchers used four different groups of people: people with asthma and a dust mite allergy, people with only asthma, people with only a dust mite allergy, and completely non-allergic subjects. They extracted the T-cells from each individual of the four different experimental groups and exposed the samples to the dust mite particles.

The results of the experiment found that a specific subset of helper T-cells called (IL)-9 Th2 expressed dust mite reactive cells were more prevalent in the blood of people with asthma and a dust mite allergy than people who are only allergic to dust mites. Further analysis exposed the potential of an increased cytotoxic potential in the IL9-TH2 cells so that they could kill other cells and drive inflammation. Cytotoxic potential is the ability for T-cells or any other substance to cause damage for cells. This increased cytotoxicity in T-cells allows them to release more toxic chemicals that destroy any infected cells, in this case dust mite cells. Thus subjects with asthma and dust mite allergies had a more effective inflammatory response than just subjects with a dust mite allergy however still displayed the common symptoms such as inflammation, sneezing, runny nose, etc.


In the same experiment, another subset of T-cells expressed an interferon response signature that coded for a protein called TRAIL in the blood of the non-allergic subject group. Interferons are signaling proteins that are made and released by host cells in response to viruses. Typically, infected host cells will release interferons, causing nearby cells to increase their anti-virus defenses. Interferons will most likely be used as a third line of defense in the nonspecific defense system if there are still multiplying viruses. The interferons diffuse to nearby cells and bind to their membrane receptors, thus hindering the ability of the virus to multiply in these cells. The function of TRAIL could dampen the activation of helper T cells, resulting in a lack of inflammatory symptoms. These subjects have less T-cell driven inflammation in response to the dust mite allergens and therefore less allergy symptoms.

Researchers have made a phenomenal breakthrough by using RNA transcription to identify types of cells that are active in people with allergies and asthma. By using genomic studies and detecting the risk of developing asthma and allergies in children, medical experts could treat them with the TRAIL T-cells so that the immune response results in no physical symptoms. Because TRAIL T-cells result in a lack of inflammatory symptoms, allergy attacks in children with asthma could be prevented or less severe. This could be administered through injections, similar to an epipen.


Educational Content

Q: What is the function of a T-cell?

A: A T-cell is a type of lymphocyte or a white blood cell that can bind to various cells in the body for the purpose of destroying infected cells and attacking antigens. In this article, the T-cells produce helper T-cells that inhibit the spread of the dust mite allergens.


Q: What is the role of RNA transcription in gene expression?

A: The goal of transcription is to make an RNA copy of a gene’s DNA sequence. The RNA sequence is used as a template to assemble the chain of amino acids that form a protein through a process called translation. The protein is responsible for carrying out the task that the gene programmed it to do.


Citations

  1. https://www.sciencedaily.com/releases/2020/06/200612172234.htm

  2. https://www.asthma.com/understanding-asthma/what-is-asthma/

  3. https://journals.lww.com/jaanp/Abstract/2019/07000/Understanding_the_genetics_of_asthma_and.3.aspx

  4. No changes were made to the following image, Asthma | AJC1 | Flickr, License: Creative Commons Legal Code


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