Allergies

2019 Life Sciences

With the coming of Spring, many people will start wishing for rain in hopes that rain will help wash away the pollen that is contributing to their allergies. Although allergies can occur year round with different allergens being more prominent at different times of years, Spring is often known as allergy season due to the myriad of pollen and other allergens that are present.

What Causes Allergies

Allergies are the result of an overreactive immune system that reacts to seemingly harmless substances – such as dust, pollen, and pet dander. When the body identifies a substance as harmful it stimulates the immune system to release certain chemicals – including histamines – which is what leads to allergy symptoms.

Histamines triggers inflammation and dilates blood vessels to help immune cells get to the site of infection. However when the body is responding to harmless substances – the allergen – the lack of injury or infection can lead to symptoms such as itching, rash, a runny nose, or even anaphylaxis .

Scientists are still trying to determine exactly what triggers allergies and why some people reach to certain allergens while others don’t. Especially since allergies can develop at any age, but it is less likely once someone is past their forties because a weakening immune system typically means less severe reactions. However, scientists have concluded that allergic rhinitis is increasing and have come up with two hypothesis for why this might be the case.

  1. Increase airborne pollutants – With the deteriorating air quality, people are now exposed to more and more air pollutants which can lead to more triggers for allergies.
  2. Hygiene hypothesis – We currently live in a more sanitary environment compared to the past which can increase susceptibility and suppress the natural development of the immune system. As a result, our immune system is reacting to allergens instead.

What Can Be Done

Medication

Antihistamines – these work to reduce or block histamines and stop allergy symptoms 
ex. Zyrtec(Cetirizine), Bendadryl (Diphenhydramine), Optivar (Azelastine eye drops)

Decongestants – these help shrink swollen nasal tissues and blood vessels to reduce symptoms and can be combined with antihistamines

Steroids – these help reduce inflammation and have to be taken regularly even when there are no symptoms
ex. Flonase (fluticasone), Alrex (loteprednal opthamlmic eye drop)

Mast Cell Stabilizers – these prevent the release of histamines from mast cells and offers some anti-inflammatory effects

Leukotriene Modifiers – these block the effects of leukotrienes – produced by the body in response to allergic reaction – and are used to treat asthma and nasal allergies
ex. Singulair (montelukast) the only FDA approved leukotriene modifer

Why Don't They Always Work

Medications can become less effective due to drug tolerance where the body becomes desensitized to their effects. While increasing dosage can work temporarily it is not a long term solution. There is two types of drug tolerance:

  1. Dynamic Tolerance – the cell becomes less responsive the longer it is exposed to a drug
  2. Kinetic Tolerance – the body breaks down and more actively excretes the drug thereby lowering concentration

The best way to deal with tolerance is sometimes to take a break from the drug for a while to rid your body of the substance. During this time, you may consider taking a different drug to help relieve your symptoms. You can also consider taking different drugs for different symptoms – such as having a drug to manage daily symptoms and another to treat an acute event.

Unfortunately the causes of the diminished effects of antihistamines is less clear. In fact, sometimes it doesn’t matter how long or frequent drugs are used before tolerance occurs.

Allergy Shots - Immunotherapy

This method relies on getting your body used to the allergen. With allergy shots, the patients will need to routinely visit the doctor to get a dose of the allergen. The doctor will gradually increase exposure while reducing time between shots. While it is not a cure, it is meant to help reduce symptoms as the body becomes more accustomed to the allergen.

Home Remedies (for nasal allergies)

Allergy-Proofing the House – This can consist of cleaning the house, using an air filter, removing clothes after coming in, and shutting the window to prevent pollen from coming in. The purpose is to reduce contact with allergens while at home.

Saline Sprays – Salt water is used to rinse nasal passages and clear out allergens and irritants.

Supplements – There is some evidence that some supplements can help reduce nasal allergies.
ex. Butterbur

Hydration – It is important to stay hydrated and drink plenty of water to prevent sinuses.

Steam – This can include use of a humidifier or vaporizer, or taking a long shower. Steam can help clear nasal passages.

The Future - Gene Therapy

With gene therapy, a single session of treatment can offer life-long protection compared with the series of shots or repeated medication. Currently, research is focused on asthma and severe allergies. Allergy symptoms comes from immune cells reacting to proteins in allergens. As a result, scientists are working on wiping the memory of T-cells and desensitizing the immune system so that it tolerates the protein.

Recently, Ray Steptoe at the UQ Diamantina Institute has conducted research on asthma and has seen some hopeful results. In his research, he inserted gene that regulates allergen protein into blood stem cells and found that the engineered cell produced new blood cells that express the protein. These cells targeted specific immune cells to turn off allergic response. He hopes on working to make gene therapy simpler and safer to use across a wide population.

Gene therapy and its ability to target how the immune system responds to allergens may well be the future of allergy treatment.

References

More, D., MD. (2019, March 18). What to Do If Your Allergy Drugs Stop Working. Retrieved from https://www.verywellhealth.com/can-allergy-medicines-really-stop-working-83146

Stewart, K. (2015, January 09). Adults Aren’t Immune From First-Time Allergies (N. Jones MD, Ed.). Retrieved from https://www.everydayhealth.com/allergies/understanding-adult-onset-allergies.aspx

University of Queensland. (2017, June 02). Gene therapy could ‘turn off’ severe allergies. Retrieved from https://www.sciencedaily.com/releases/2017/06/170602090731.htm

WebMD. (n.d.). Drugs to Treat Allergy Symptoms. Retrieved from https://www.webmd.com/allergies/allergy-medications#1


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