Sports Immunology: Cellular health matters!

The study of the immune system or immunology has been mainly associated with cancer research and vaccine production. Still, new perspectives are rising up due to technological advancements and research opportunities.

Health in sports has been conventionally focused on cardio, strength, and agility; cellular health and molecular biology have been kept distant when considering health aspects for athletes. As is evident that physical and mental health aspects such as muscle mass, visceral fat, BMI, basal metabolic rate, etc., have been used extensively to judge the performance and endurance of athletes and improve upon.

The pandemic has unintentionally made immunology popular to the general public. It has been in the news almost daily, revealing many applications in different previously less explored areas such as sports. Although not for the first time, understanding immune response during strenuous activity and assessing muscle damage activating immune response has been studied since 1985. Still, a lot remains to be discovered. 

    

Due to pandemic respiratory inflammation or upper respiratory tract infection has been prevalent throughout all age groups. Upper respiratory infection, which accounts for 35–65 percent of non-injury-related visits to a sports medicine clinic, is the most pervasive reason for non-injury visits. Athletes who engage in high-intensity exercise may suffer from recurrent or persistent respiratory disease, negatively influencing their health and performance. Athletes' upper respiratory symptoms can be caused by various factors, including common respiratory infections, viral reactivation, allergic reactions to aeroallergens, and exercise-induced damage to respiratory epithelial membrane integrity. 

In up to 10% of athletes competing in Olympic and international contests, upper respiratory disease hampered their training and ability to perform. These events have led to the belief that respiratory tract infections are frequent among top athletes, although data to support this claim is unclear and appears to be sport-specific. However, athletes who report an illness may see a drop in performance, even after years of rigorous training. Although temporary exercise-induced immune suppression might increase infection susceptibility, not all infections have an infectious cause, and exposure is impacted by other lifestyle and environmental variables.

                      

Not restricted to respiratory illnesses, muscle damage leads to damage-associated molecular patterns or DAMPs, leading to inflammation and initial immune response locally. A study published in 2019 analyzed the effects of exercise and training in cancer patients and found that exercise training reduces pro-inflammatory markers in cancer survivors, with the most substantial evidence for combined training and for prostate and breast cancer survivors. 
Inflammation, remarkably immune inflammation, is an essential and complex biological process that protects the body from potential damage caused by infections, injuries, or damage. An effective inflammatory response is based on intricate cellular and molecular interactions between the immune system, the vascular system, and the fabric. Therefore, it is essential to understand the cellular and molecular biology of inflammation and immune resolution. It is equally crucial that inflammation is resolved; when inflammation is not adequately controlled, it may possibly lead to mediated inflammatory, immunological diseases (for example, rheumatoid arthritis, intestinal inflammatory disease, psoriasis, asthma, vasculitis). 
Cytokines are small molecules (~5–20 kDa) that participate in the cellular signaling of immune system cells. Cytokines can be pro-inflammatory, anti-inflammatory, or pleiotropic in function depending on the cell type and state of local immune inflammation. There are many types of Cytokines, including chemokines, interferons, interleukins, lymphokines, tumor necrosis factors but generally not hormones or growth factors (despite some terminological overlap). All those types of cytokines are produced by a broad range of cells, including immune cells like macrophages, B lymphocytes, T lymphocytes, and mast cells, as well as endothelial cells, fibroblasts, and various stromal cells; a given cytokine may be produced by more than one type of cell. These chemokines are responsible for calling pro or anti-inflammatory cells the inflamed site. Therefore understanding the levels of cytokines and chemokines in circulating blood or peripheral blood of athletes undergoing strenuous training and exercise may provide a more profound and comprehensive insight into the immunological health of the individual. As in cardio, the athletes train to limit the maximum heartbeats per minute; the same can be valid with circulating cytokines as the project the level of inflammation proportional to their concentration depending on the type of cytokine. But for this large amount of data needs to be generated to understand which cytokines need to be chosen as a viable parameter of athletic health, what is the range of optimum circulating cytokines. 
This is an achievable goal due to technological advancements in the past two decades. As athletes focus on the physiological aspects of health, a cellular aspect may provide better insight into their immune health and risk of infection.

References:

1. Gleeson M, Pyne DB. Respiratory inflammation and infections in high-performance athletes. Immunol Cell Biol. 2016;94(2):124-131. doi:10.1038/icb.2015.100
2. JM W, PA G. How Participating in Sports Causes Manifestations and Mimics of Allergic Conditions and What to Do About Them for Optimum Performance. J allergy Clin Immunol Pract. 2020;8(7):2220-2221. doi:10.1016/J.JAIP.2020.04.007
3. Khosravi N, Stoner L, Farajivafa V, Hanson ED. Exercise training, circulating cytokine levels and immune function in cancer survivors: A meta-analysis. Brain Behav Immun. 2019;81:92-104. doi:10.1016/j.bbi.2019.08.187
4. Taams LS. Inflammation and immune resolution. Clin Exp Immunol. 2018;193(1):1. doi:10.1111/CEI.13155

1.        Author - Gaurang Telang