Salivary IgA as a Potential Biomarker in the Evaluation of Respiratory Tract Infection Risk in Athletes

Immunosurveillance associated with upper respiratory symptoms in elite swimmers: The 8-month period leading into Commonwealth Games

OBJECTIVES

To monitor individual mucosal immunity and identify potential risk factors of upper respiratory symptoms in elite swimmers over a competitive season.

DESIGN

Eight-month longitudinal study, observing mucosal immunity, Epstein-Barr virus status, training loads and illness symptoms of elite international swimmers, leading into the Commonwealth Games 2018.

METHODS

Participants were fourteen elite swimmers (age ± standard deviation = 19.9 ± 0.8 years, height = 178.9 ± 6.3 cm, and mass = 75.0 ± 7.7 kg). Self-reported upper respiratory symptoms, training load and saliva samples were collected weekly. Venous blood samples were taken at study commencement to determine Epstein-Barr virus status.

RESULTS

Throughout the study, 70 episodes of upper respiratory symptoms were recorded resulting in 34 days of missed training. Incidence (p = 0.001), severity (p = 0.022), and duration of upper respiratory symptoms (p = 0.001) were significantly higher during high training loads, compared to low. Eight swimmers (61 %) had evidence of past infection with Epstein-Barr virus, but this had no relationship with incidence, severity, or duration of upper respiratory symptoms (p > 0.05). Relative individual salivary immunoglobulin A concentration was 12 % lower when upper respiratory symptoms were present but was not statistically significant (p = 0.101).

CONCLUSIONS

This study highlights the importance of individual athlete monitoring, to identify swimmers at increased illness risk. Identification of possible risk factors for upper respiratory symptoms, such as increased training load, may allow for modifications in training or other illness preventative strategies for elite swimmers.

Influence of iron supplementation on fatigue, mood states and sweating profiles of healthy non-anemic athletes during a training exercise: A double-blind, randomized, placebo-controlled, parallel-group study

Iron is specifically important to athletes, and attention has grown to the association between sports performance and iron regulation in the daily diets of athletes. The study presents new insights into stress, mood states, fatigue, and sweating behavior among the non-anemic athletes with sweating exercise habits who consumed a routine low dose (3.6 mg/day) of iron supplementation. In this double-blind, randomized, placebo-controlled, parallel-group study, both non-anemic male (N = 51) and female (N = 42) athletes were supplemented either with a known highly bioavailable iron formulation (SunActive® Fe) or placebo during the follow-up training exercise period over four weeks at their respective designated clinical sites. The effect of oral iron consumption was examined on fatigue, stress profiles, as well as the quality of life using the profile of mood state (POMS) test or a visual analog scale (VAS) questionnaire, followed by an exercise and well-being related fatigue-sweat. Also, their monotonic association with stress biomarkers (salivary α-amylase, salivary cortisol, and salivary immunoglobulin A) were determined using spearman's rank correlation coefficient test. Repeated measure multivariate analysis of variance (group by time) revealed that the total mood disturbance (TMD) score was significantly lower (P = 0.016; F = 6.26) between placebo and iron supplementation groups over the four weeks study period among female athletes. Also, a significant reduction in tired feeling/exhaustion after the exercise (P = 0.05; F = 4.07) between the placebo and iron intake groups was noticed. A significant within-group reduction (P ≤ 0.05) was noticed in the degree of sweat among both male and female athletes after 2 and 4 weeks of iron supplementation, while athletes of the placebo intake group experienced a non-significant within-group reduction in the degree of sweat. Overall, the result indicates routine use of low dose (3.6 mg/day) iron supplementation is beneficial for non-anemic endurance athletes to improve stress, mood states, subjective fatigue, and sweating conditions.

IgA-producing B cells in lung homeostasis and disease

Immunoglobulin A (IgA) is the most abundant Ig in mucosae where it plays key roles in host defense against pathogens and in mucosal immunoregulation. Whereas intense research has established the different roles of secretory IgA in the gut, its function has been much less studied in the lung. This review will first summarize the state-of-the-art knowledge on the distribution and phenotype of IgA⁺ B cells in the human lung in both homeostasis and disease. Second, it will analyze the studies looking at cellular and molecular mechanisms of homing and priming of IgA⁺ B cells in the lung, notably following immunization. Lastly, published data on observations related to IgA and IgA⁺ B cells in lung and airway disease such as asthma, cystic fibrosis, idiopathic pulmonary fibrosis, or chronic rhinosinusitis, will be discussed. Collectively it provides the state-of-the-art of our current understanding of the biology of IgA-producing cells in the airways and identifies gaps that future research should address in order to improve mucosal protection against lung infections and chronic inflammatory diseases.

Disease-related disgust promotes antibody release in human saliva

The behavioral immune system (BIS) comprises manifold mechanisms, that may assist the physiological immune system (PIS) in counteracting infection and can even reduce the risk of contagion. Previous studies have found initial evidence for possible interactions between the two systems. However, most of these findings were correlative and have not been replicated. Further, none of these studies examined whether disease stimuli that indicate an enhanced airborne transmission risk may trigger a different immune response in comparison to stimuli that predominantly evoke core disgust. In the present study, we employed a video-priming approach to get further insight in the influence of the perception of disgust- and disease-related stimuli on the rapid physiological immune response, as indicated by changes of secretory immunoglobulin A (S-IgA) in saliva. We created three video primers that represented different categories of disgust- and/or disease-associated content. Two of the videos showed disease-related situations that were associated with contagious respiratory virus infections, varying in concealment of aerosols. The third video incurred no heightened airborne contagion risk, but comprised situations that are known to elicit core disgust, such as rotten foods, decaying animal carcasses, or cockroaches. A fourth video acted as control showing landscape impressions. The different video primers varied in their contagion risk and disgust-evoking potential. Given the role of S-IgA in the mucosal immune defense, we expected differences in the S-IgA response between the two videos indicating a heightened airborne contagion risk and the core disgust video, with the highest S-IgA to occur after the aerosol video. For this, we used the data of 107 healthy participants in a between-subjects design with the four video primers. We found a significant increase of S-IgA in response to both the disease- and the disgust-related videos, which correlated positively with the perceived contagion risk of the displayed situations. Nevertheless, there was no significant difference in the increase between the three disease- and disgust-related videos. We also found that people with a high contamination disgust produced less S-IgA in such situations, which is a hint for a compensating relationship between the BIS and PIS. Our observations suggest that the mere visual perception of videos showing realistic situations of an increased contagion risk can elicit a heightened release of salivary antibodies.

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Realistic videos of respiratory diseases are efficient to trigger immune responses.

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Secretory Immunoglobulin A (S-IgA) in saliva increases after video-priming.

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S-IgA increase is positively correlated with perceived contagion risk.

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S-IgA increase is inversely correlated with the trait contamination disgust.

Physical exercise, immune response, and susceptibility to infections-current knowledge and growing research areas

This review presents state-of-the-art knowledge and identifies knowledge gaps for future research in the area of exercise-associated modifications of infection susceptibility. Regular moderate-intensity exercise is believed to have beneficial effects on immune health through lowering inflammation intensity and reducing susceptibility to respiratory infections. However, strenuous exercise, as performed by professional athletes, may promote infection: in about half of athletes presenting respiratory symptoms, no causative pathogen can be identified. Acute bouts of exercise enhance the release of pro-inflammatory mediators, which may induce infection-like respiratory symptoms. Relatively few studies have assessed the influence of regularly repeated exercise on the immune response and systemic inflammation compared to the effects of acute exercise. Additionally, ambient and environmental conditions may modify the systemic inflammatory response and infection susceptibility, particularly in outdoor athletes. Both acute and chronic regular exercise influence humoral and cellular immune response mechanisms, resulting in decreased specific and non-specific response in competitive athletes. The most promising areas of further research in exercise immunology include detailed immunological characterization of infection-prone and infection-resistant athletes, examining the efficacy of nutritional and pharmaceutical interventions as countermeasures to infection symptoms, and determining the influence of various exercise loads on susceptibility to infections with respiratory viruses, including SARS-CoV-2. By establishing a uniform definition of an "elite athlete," it will be possible to make a comparable and straightforward interpretation of data from different studies and settings.

The Impacts of Ramadan Intermittent Fasting on Saliva Flow-Rate and Metabolic Data: A Systematic Review

The aim of this systematic review was to report the impacts of Ramadan intermittent fasting (RIF) on salivary flow-rate (SFR) and metabolic parameters. A thorough literature search was carried out using the databases PubMed and Scopus from their inception up to 15 July 2021. The Boolean connectors used in PubMed were (Saliva [Mesh] AND Fasting [Mesh]). The same keywords were used in Scopus. Inclusion criteria were defined using PICOS. The research included all original studies involving “healthy” adults and published in English. Methodological quality assessment was performed utilizing the Joanna Briggs Institute Critical Appraisal Tool, which allows attributing scores from 1 to 11 to the selected studies. Two authors carried out the literature search, study selection, and data extraction. Differences on issues were resolved by a third author if necessary. The systematic review protocol was registered within the “Open Science Framework” (Doi: 10.17605/OSF.IO/DE7BH). Six articles met the inclusion criteria. All studies were heterogeneous and had a high score of bias and several methodological differences. The following parameters were collected: SFR, melatonin, cortisol, glucose, immunoglobulin A (IgA), uric-acid, alkaline phosphatase (ALP), and aspartate aminotransferase (AST). The SFR decreased by 10% during Ramadan in fasting subjects. The circadian pattern of melatonin remained unchanged during Ramadan, but melatonin levels dropped significantly from baseline. The salivary cortisol levels were unchanged or increased during Ramadan. The salivary glucose levels were decreased. ALP increased significantly, whilst uric-acid and AST decreased significantly. Salivary IgA decreased during the last week of Ramadan. To conclude, there is a trend toward a decrease in SFR and the content of the majority of the biomarkers investigated, with the exception of ALP and uric-acid. These changes cannot be easily attributed to any single factor (hydration status, dietary habits, physical activity, or hygiene habits).

Systematic Review Registration: [https://osf.io/de7bh/], identifier [Doi: 10.17605/OSF.IO/DE7B].

Respiratory Viral Infections in Athletes: Many Unanswered Questions

Upper respiratory tract infections (“common cold”) are the most common acute illnesses in elite athletes. Numerous studies on exercise immunology have proposed that intense exercise may increase susceptibility to respiratory infections. Virological data to support that view are sparse, and several fundamental questions remain. Immunity to respiratory viral infections is highly complex, and there is a lack of evidence that minor short- or long-term alterations in immunity in elite athletes have clinical implications. The degree to which athletes are infected by respiratory viruses is unclear. During major sport events, athletes are at an increased risk of symptomatic infections caused by the same viruses as those in the general population. The symptoms are usually mild and self-limiting. It is anecdotally known that athletes commonly exercise and compete while having a respiratory viral infection; there are no virological studies to suggest that such activity would affect either the illness or the performance. The risk of myocarditis exists. Which simple mitigation procedures are crucial for effective control of seasonal respiratory viral infections is not known.

The Role of IgA in Chronic Upper Airway Disease: Friend or Foe?

Chronic upper airway inflammation is amongst the most prevalent chronic disease entities in the Western world with prevalence around 30% (rhinitis) and 11% (rhinosinusitis). Chronic rhinitis and rhinosinusitis may severely impair the quality of life, leading to a significant socio-economic burden. It becomes more and more clear that the respiratory mucosa which forms a physiological as well as chemical barrier for inhaled particles, plays a key role in maintaining homeostasis and driving disease. In a healthy state, the mucosal immune system provides protection against pathogens as well as maintains a tolerance toward non-harmful commensal microbes and benign environmental substances such as allergens. One of the most important players of the mucosal immune system is immunoglobulin (Ig) A, which is well-studied in gut research where it has emerged as a key factor in creating tolerance to potential food allergens and maintaining a healthy microbiome. Although, it is very likely that IgA plays a similar role at the level of the respiratory epithelium, very little research has been performed on the role of this protein in the airways, especially in chronic upper airway diseases. This review summarizes what is known about IgA in upper airway homeostasis, as well as in rhinitis and rhinosinusitis, including current and possible new treatments that may interfere with the IgA system. By doing so, we identify unmet needs in exploring the different roles of IgA in the upper airways required to find new biomarkers or therapeutic options for treating chronic rhinitis and rhinosinusitis.

Beyond the Finish Line: The Impact and Dynamics of Biomarkers in Physical Exercise-A Narrative Review

The research of biomarkers continues to emerge as a developing academic field which is attracting substantial interest. The study of biomarkers proves to be useful in developing and implementing new screening methods for a wide variety of diseases including in the sports area, whether for leisure activities or professional sports. Novel research has brought into question the immune system and the limitations it may impose on sports practicing. As the well-being of athletes is a priority, the state of their immune function offers valuable information regarding their health status and their ability to continue training. The assessment of various biomarkers may contribute to a more accurate risk stratification and subsequent prevention of some invalidating or even fatal pathologies such as the sudden cardiac death. Therefore, we have reviewed several studies that included sports-related pathology or specific morphofunctional alterations for which some immune biomarkers may represent an expression of the underlying mechanism. These include the defensins, immunoglobulin A (IgA), interleukin-6 (IL-6), the tumoral necrosis factor α (TNF-α), and the white blood cells (WBC) count. Similarly, also of significant interest are various endocrine biomarkers, such as cortisol and testosterone, as well as anabolic or catabolic markers, respectively. Literature data highlight that these values are greatly influenced not only by the duration, but also by the intensity of the physical exercise; moderate training sessions actually enhance the immune function of the body, while a significant increase in both duration and intensity of sports activity acts as a deleterious factor. Therefore, in this paper we aim to highlight the importance of biomarkers’ evaluation in connection with sports activities and a subsequent more adequate approach towards personalized training regimens.

Effect of tiger milk mushroom (Lignosus rhinocerus) supplementation on respiratory health, immunity and antioxidant status: an open-label prospective study

Tiger milk mushroom (TMM; Lignosus rhinocerus) have been used for a long time by indigenous communities in South East Asia regions as traditional medicine for different ailments, including respiratory disorders. The beneficial effects of TMM have been proven through in vivo and in vitro models, but these effects have yet to be validated in a clinical study. In this study, the beneficial effects of TMM supplementation were investigated in 50 voluntary participants. Participants were required to take 300 mg of TMM twice daily for three months. Level of interleukin 1β (IL-1β), interleukin 8 (IL-8), immunoglobulin A (IgA), total antioxidant capacity, malondialdehyde (MDA), 3-nitrotyrosine (3-NT), 8-hydroxydeoxyguanosine (8-OHdG), pulmonary function and respiratory symptoms were assessed during baseline and monthly follow-up visits. Results demonstrated that supplementation of TMM significantly (p < 0.05) suppressed the level of IL-1β, IL-8, MDA, as well as respiratory symptoms. In additional to that, TMM also significantly (p < 0.05) induced the level of IgA, total antioxidant capacity, as well as pulmonary function. Analyses of data indicated that gender and BMI were factors influencing the outcomes of antioxidant status. Collectively, our findings suggested that TMM supplementation effectively improves respiratory health, immunity and antioxidant status.

The Impact of Acute and Chronic Exercise on Immunoglobulins and Cytokines in Elderly: Insights From a Critical Review of the Literature

The level of immunoglobulins and cytokines changes with an ageing immune system. This review summarizes findings from studies that have examined the impact of acute and chronic exercise on immunoglobulins and cytokines in the elderly. Our literature analysis revealed that acute endurance exercise resulted in increased secretory salivary immunoglobulin A (SIgA), while acute bouts of muscle strengthening exercise (i.e., isokinetic, eccentric, knee extensor exercise) increased plasma/muscle interleukin (IL)-6, IL-8 and tumor necrosis factor alpha (TNF-α) levels. Chronic exercise in the form of short-term endurance training (i.e., 12-16 weeks) and long-term combined endurance and resistance training (i.e., 6-12 months) induced increases in salivary SIgA concentration. We additionally identified that short-term endurance training at moderate intensities and the combination of endurance, strength, balance, and flexibility training increase plasma IL-10 and reduce plasma IL-6 and TNF-α in healthy elderly adults and male patients with chronic heart failure. Strength training for 6-12 weeks did not alter plasma IL-1β, IL-2, IL-6 and TNF-α concentration in healthy elderly adults and patients with chronic-degenerative diseases, while 12 weeks of resistance training decreased muscle TNF-α mRNA in frail elderly individuals. Short-term (i.e., 10-24 weeks) moderate- to high-intensity strength training reduced LPS–IL-6, LPS, IL-1β, LPS–TNF-α and circulating concentrations of TNF-α and increased IL-10 in healthy elderly women and older people with cognitive impairment, respectively. In conclusion, it appears that acute bouts of endurance exercise and short-term chronic exercise training exercise are appropriate methods to enhance mucosal immune function, reduce systemic markers of inflammation, and promote anti-inflammatory processes in elderly individuals.