Respiratory infection risk in athletes: association with antigen-stimulated IL-10 production and salivary IgA secretion.
ABSTRACT The purpose of this study was to examine factors influencing susceptibility to upper respiratory tract infections (URTI) in 18-35-year-old men and women engaged in endurance-based physical activity during the winter months. Eighty individuals (46 males, 34 females) provided resting blood and saliva samples for determination of markers of systemic immunity. Weekly training and illness logs were kept for the following 4 months. Thirty subjects did not experience an URTI episode and 24 subjects experienced 3 or more weeks of URTI symptoms. These illness-prone subjects had higher training loads and had ∼2.5-fold higher interleukin (IL)-4 and IL-10 production by antigen-stimulated whole blood culture than the illness-free subjects. Illness-prone subjects also had significantly lower saliva S-IgA secretion rate and higher plasma IgM (but not IgA or IgG) concentration than the illness-free subjects. There were no differences in circulating numbers of leukocyte subtypes or lymphocyte subsets between the illness-prone and illness-free subjects. The production of IL-10 was positively correlated and the S-IgA secretion rate was negatively correlated with the number of weeks with infection symptoms. It is concluded that high IL-10 production in response to antigen challenge and low S-IgA secretion are risk factors for development of URTI in physically active individuals.
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ABSTRACT: Abstract The aim of this study was to investigate the influence of mannose-binding lectin 2 (MBL2)-exon-1 gene polymorphisms on upper respiratory tract infection (URTI) incidence among endurance athletes. To this end, 100 healthy elite male athletes participating in the study were classified as either healthy or prone to frequent URTI. Blood samples, DNA isolation, multiplex polymerase chain reaction (PCR) and conventional PCR-RFLP were performed. Genomic DNA was extracted from peripheral leukocytes of whole blood samples using the QIAmp DNA Blood Mini Kit. For comparison of the distribution of genotypes between two groups and for estimating odds ratios (OR) for URTI susceptibility in relation to the MBL2-exon-1 polymorphism, Pearson's chi-square and logistic regression method were used, respectively. The MBL2-exon-1 genotype distribution differed between athletes with URTI and healthy athletes (χ(2) = 7.81, p = 0.02). The AO and AO + OO genotypes of MBL2 were observed at a greater frequency in the illness-prone group compared with the healthy group (34.04% vs. 11.32%). In conclusion, findings from this study have identified a potential role of genetic variation in influencing the risk for URTI in athletic populations and single-nucleotide polymorphisms (SNPs) in the MBL2-exon-1 genes were associated with an altered risk profile. These measures may have a predictive value in the identification of individuals who are more likely to experience recurrent infections when exposed to high physical stress in the areas of athletic endeavour.European journal of sport science. 03/2014;
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ABSTRACT: Background Obesity is a severe health problem worldwide which leads to multiple comorbidities including type 2 diabetes mellitus and cardiovascular diseases. Inflammation has been found to be an important characteristic of adipose tissue in obese subjects. However, obesity is also associated with compromised immune responses to infections and the impact of obesity on immune function has not been fully understood.Subjects/Methods To clarify the role of obesity in the immune responses, we investigated the Toll-like receptor (TLR)-induced cytokine secretion by leukocytes from obese and lean subjects. We also investigated the relationship between insulin-induced intracellular signaling and cytokine production using peripheral blood mononuclear cells (PBMC) and a monocytic cell line THP-1.ResultsWe found decreased TLR-induced interferon-gamma (IFN-γ), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) secretions and elevated IL-10 secretion by leukocytes from obese subjects when compared with lean controls. PBMCs from obese subjects showed enhanced basal Akt and glycogen synthase kinase 3β (GSK-3β) phosphorylation which did not further increase with insulin and lipopolysaccharide (LPS) stimulation. We also found that LPS-induced IκBα degradation was inhibited in PBMCs from obese subjects. By using THP-1 cells with GSK-3β knockdown or cells treated with hyperinsulinemic and high fatty acid conditions, we found that LPS-induced NF-κB activation was inhibited and cAMP response element-binding protein (CREB) activation was enhanced.Conclusions These findings indicate that GSK-3β is important in the regulation of NF-κB and CREB activation in leukocytes under the metabolic condition of obesity. Our study revealed a key mechanism through which metabolic abnormalities compromise leukocyte functions in people with obesity.International Journal of Obesity accepted article preview online, 23 May 2014; doi:10.1038/ijo.2014.93.International journal of obesity (2005) 05/2014; · 5.22 Impact Factor
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ABSTRACT: Athletes engaged in strenuous training might experience transient immune suppression that could lead to greater incidence of upper respiratory tract infections (URTI). Since interleukin 21 (IL-21) stimulates immunoglobulin A (IgA) secreting cells and a low level of this immunoglobulin is associated with increased incidence of URTI, the aim of the present study was to investigate the effect of a basketball match on salivary cortisol (sC), salivary IL-21 (sIL-21) and salivary IgA (sIgA) levels. Twenty male basketball players participated in an official game in two teams (10 players in each team). The saliva samples were collected before the warm-up and approximately 10-15 min after the end of the match and were analysed by ELISA methods. sC concentration increased significantly after the match while sIL-21 level was reduced (p < 0.05). In opposition to the study's hypothesis, sIgA level did not change in response to the match. The present findings suggest that a basketball match is sufficiently stressful to elevate sC concentration and attenuates the sIL-21 output without compromising the sIgA level. It is reasonable to speculate that the stability of sIgA acute responses to the match, despite the decrement in sIL-21, indicates that other mechanisms rather than IL-21 stimulating B cell proliferation/differentiation might modulate IgA concentration and secretion rate.Biology of Sport 12/2013; 30(4):243-7. · 0.42 Impact Factor