Coronavirus disease 2019 (COVID-19) is a virus-induced respiratory disease that may progress to acute respiratory distress syndrome (ARDS) and is triggered by immunopathological mechanisms that cause excessive inflammation and leukocyte dysfunction. Neutrophils play a critical function in the clearance of bacteria with specific mechanisms to combat viruses. The aim of this review is to highlight the current advances in the pathways of neutrophilic inflammation against viral infection over the past ten years, focusing on the production of neutrophil extracellular traps (NETs) and its impact on severe lung diseases, such as COVID-19. We focused on studies regarding hyperinflammation, cytokine storms, neutrophil function, and viral infections. We discuss how the neutrophil’s role could influence COVID-19 symptoms in the interaction between hyperinflammation (overproduction of NETs and cytokines) and the clearance function of neutrophils to eliminate the viral infection. We also propose a more in-depth investigation into the neutrophil response mechanism targeting NETosis in the different phases of COVID-19.

This review presents literature that highlights saliva’s utility as a biofluid in the diagnosis and monitoring of COVID-19. A systematic search was performed in 5 electronic databases (PubMed, Embase, LILACS, Scopus, and Web of Science). Studies were eligible for inclusion if they assessed the potential diagnostic value and/or other discriminatory properties of biological markers in the saliva of patients with COVID-19. As of July 22, 2020, a total of 28 studies have investigated the presence of SARS-CoV-2 RNA in saliva. Several of those studies confirmed reliable detection of SARS-CoV-2 in the saliva of patients with COVID-19. Saliva offered sensitivity and specificity for SARS-CoV-2 detection comparable to that of the current standard of nasopharyngeal and throat swabs. However, the utility of saliva in diagnosing COVID-19 infection remains understudied. Clinical studies with larger patient populations that measure recordings at different stages during the disease are still necessary to confirm the accuracy of COVID-19 diagnosis with saliva. Nevertheless, the utility of saliva as a diagnostic tool opens the possibility of using rapid and less invasive diagnostic strategies by targeting bioanalytes rather than the pathogen.

Strenuous exercise is detrimental to athletes because of the overproduction of reactive oxygen species. Melatonin, a classic antioxidant, has been shown to exhibit beneficial effects regarding intense exercise and tissue repair. In this study, we evaluated the onset and resolution of inflammation in melatonin-treated and nontreated rats subjected to a strenuous exercise session. We also analyzed the formation of thiobarbituric acid reactive substances (TBARS) and the activities of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Control and treated rats were subjected to exhaustive exercise after a period of 10 days of melatonin treatment (20 mg/dL). Plasma and muscle levels of tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 6 (IL-6), cytokine-induced neutrophil chemoattractant-2-alpha/beta (CINC-2α/β), l-selectin, macrophage inflammatory protein-3-alpha (MIP-3α), and vascular endothelial growth factor (VEGF) were measured prior to, immediately after, and 2 hr after exercise. Our data revealed decreases in the muscle concentrations of IL-1β (35%), TNF-α (13%), IL-6 (48%), and TBARS (40%) in the melatonin-treated group compared with the control group. We also observed decreases in the plasma concentrations of IL-1β (17%) in the melatonin-treated group. VEGF-α concentrations and SOD activity increased by 179% and 22%, respectively, in the melatonin-treated group compared with the control group. We concluded that muscle inflammation and oxidative stress resulting from exhaustive exercise were less severe in the muscles of melatonin-treated animals than in the muscles of control animals. Thus, melatonin treatment may reverse exercise-induced skeletal muscle inflammation and stimulate growth factor synthesis.

Background Evidence suggests that exercise improves neutrophil function. The decreased functional longevity of neutrophils and their increased clearance from infectious sites contribute to the increased susceptibility to infection and severity of infection observed in patients with diabetes. Objective Herein, we investigated the effects of a dance program on neutrophil number, function, and death in type 2 diabetes mellitus (T2DM) patients and healthy volunteers. Methods Ten patients with T2DM and twelve healthy individuals participated in a moderate-intensity dance training program for 4 months. The plasma levels of leptin, free fatty acids (FFAs), tumour necrosis factor-α (TNF-α), C-reactive protein (CRP), interleukin-1β (IL-1β), and interleukin-1 receptor antagonist (IL-1ra); neutrophil counts; extent of DNA fragmentation; cell membrane integrity; and production of TNF-α, interleukin-8 (IL-8), interleukin-6 (IL-6), and IL-1β in neutrophils were measured before and after training. Results Training reduced plasma levels of TNF-α (1.9-fold in controls and 2.2-fold in patients with T2DM) and CRP (1.4-fold in controls and 3.4-fold in patients with T2DM). IL-1ra levels were higher in the control group (2.2-fold) after training. After training, neutrophil DNA fragmentation was decreased in patients with T2DM (90%), while the number of neutrophils increased (70% in controls and 1.1-fold in patients with T2DM). Conclusion Dance training is a nonpharmacological strategy to reduce inflammation and improve neutrophil clearance in patients with T2DM.

In this study, the lymphocyte activation status (surface expression of CD95, CD28, CD25, and CTLA-4), lymphocyte number, lymphocyte subpopulations, lymphocyte necrosis and/or apoptosis, and lymphocyte release of reactive oxygen species (ROS) were investigated in blood samples from 16 futsal athletes before and immediately following a competitive match. Lymphocytes were isolated from the blood samples, and the cellular parameters were assessed by flow cytometry. The futsal match induced lymphocytosis and lymphocyte apoptosis, as indicated by phosphatidylserine externalization, CD95 expression, and DNA fragmentation. Additionally, the competitive match induced the necrotic death of lymphocytes. No differences in the percentage of CD4+ and CD8+ T cells or in the T-helper/suppressor profile between before and immediately after the match were observed. Additionally, after the futsal match, the CD95 and CD28 expression levels were decreased, and the lymphocytes spontaneously released higher levels of ROS. Regardless of the origin, the situation-specific knowledge of lymphocyte behavior obtained herein may facilitate the design of strategies to control the processes that result in infection and tissue injury and that subsequently decrease athletic performance.

A futsal player's performance depends on his technical and tactical skills but may be improved by a less harmful inflammatory profile that is better adjusted to his tactical position in the game. Thus, the purpose of this study was to characterize muscle lesion and inflammation in futsal players according to their positions in an official match. The participants in this study were 5 goalkeepers (23 ± 1.2 years old, body mass = 74 ± 2.5 kg, height = 178 ± 3.2 cm, body fat = 13 ± 2%, VO2max = 40 ± 2 ml·kg(-1)), 8 defenders (21 ± 1 years, body mass = 69 ± 2 kg, height = 174 ± 1 cm, body fat = 10 ± 2%, VO2max 42 ± 1 ml·kg(-1)), 8 wingers (22 ± 1 years, body mass = 68 ± 2 kg, height = 169 ± 3 cm, body fat = 11 ± 2%, VO2max = 48 ± 1 ml·kg(-1)), and 8 pivots (25 ± 2 years, body mass 71 ± 2 kg, height 173 ± 2 cm, body fat 10 ± 2%, VO2max 46 ± 2 ml·kg(-1)). Blood samples were collected from the participants before and immediately after a match. Muscle damage was detected based on CK and lactate dehydrogenase (LDH) activity. The inflammatory status was evaluated by determining C-reactive protein and cytokines (TNF-α, interleukin [IL]-1β, IL-6, IL-10, and IL-1ra). Goalkeepers showed higher LDH and IL-6 than players occupying other tactical positions, leading to the conclusion that the tactical position of futsal goalkeeper causes more inflammation and muscle damage than other positions. Moreover, this position is usually occupied by athletes with higher body mass and percentage of body fat and lower VO2max than players in the other positions.

Reactive species have great importance in sports performance, once they can directly regulate energy production, muscular contraction, inflammation, and fatigue. Therefore, the redox control is essential for athletes' performance. Studies demonstrated that l-arginine has an important role in the synthesis of urea, cell growth and production of nitric oxide, moreover, there are indications that it is also able to induce benefits to muscle antioxidant system through the upregulation of some antioxidant enzymes, and by inhibiting some pathways of reactive species production. Therefore, the aim of this study was to evaluate the effects of l-arginine supplementation on performance and oxidative stress of male rats (trained or not), submitted to a single session of high intensity exercise. Forty male Wistar rats were divided into four groups, control (C), control+l-arginine (C + A), trained (T), and trained+l-arginine (T + A). The aerobic training was conducted for 8 weeks. Data of maximum speed and time from tests were used as indicators of performance. Variables related to oxidative stress and antioxidant system were also evaluated. Aerobic training was capable to induce enhancements on animals' exercise performance and on their redox state. Additionally, supplementation improved rats' physical performance on both groups, control and trained. Different improvements between groups on the antioxidant capacity were observed. Nevertheless, considering the ergogenic effect of l-arginine and the lack of all positive adaptations promoted by the exercise training, untrained animals may be more exposed to oxidative damages after the practice of intense exercises.

The physical demands of street dancing may result in inflammation and changes in leukocyte numbers/function, impairing the health of dancers. Herein, we investigated the effect of street dancing on inflammation, adhesion molecules, and neutrophil function. Fifteen amateur dancers (mean ± SE: age 22.4 ± 1.08 years, BMI 24.8 ± 0.69 kg/m2, and body fat 12.3 ± 1.52%) participated in a single high-intensity street dance class. Blood samples were taken before and after the class. The dance class had no effect on the plasma concentration of CRP, TNF-α, IL-6, IL-10, and IL-8; however, we noted an increase in levels of IL-1β (4.06%) and sL-selectin (17.67%). The dance class resulted in a 12.36% increase in neutrophil counts, while neutrophil CD62L expression and migration were reduced (25.27% and 78.92%, resp.). After the dance class, neutrophil production of IL-8 and TNF-α increased, respectively, by 59.75% and 49.23%, in the control condition, and 43.55% and 32.22%, after LPS stimulation. A single bout of street dancing induced inflammation and reduced neutrophil migration and adhesion molecule expression. These findings may contribute to a better understanding of the susceptibility to infection after acute dance exercise.