ブックタイトル教育医学 J.Educ.Health Sci.　第63巻　第3号　通巻 第289号

概要

教育医学 J.Educ.Health Sci.　第63巻　第3号　通巻 第289号

Tatsuya USUI, Shintaro TSUJI, Nobuhito NAGAI and Chie TAKEYASUobservation after 1 hr of exercise) compared withprevious works, the observed negative correlationsmight represent a type of immunomodulation byendogenous corticosteroids that produce the endproduct of the HPA axis following substantialstress by intense types of exercise. In contrast to thetwo antimicrobial peptides, however, changes insalivary IgA levels were not associated with thosein stress markers. Corticosteroids are classicallyknown to have differential effects on lymphocytesubpopulations involved in immunoglobulinbiosynthesis by pokeweek mitogen stimulation invitro where B cell responsiveness is diminished 31) ,whereas the elevated glucocorticoids are notsufficient to suppress the antibody response 17) .Although previous studies investigated theassociation of salivary levels of IgA with thoseof cortisol during a single bout of exercise,the relationship appears to be equivocal 15) . Thepresent findings highlight the variability of stressinducedimmunological shifts in response tostrenuous exercise among innate immune factors.Furthermore, beyond these immune parametersassessed in the present study, a wide variety ofhumoral and cellular components in oral mucosaand secretions, including lactoferrin, secretoryleukocyte protease (peptidase) inhibitor (SLPI),lysozyme, and neutrophils 37) , synergistically actand provide a first-line protective barrier againstpathogens, yielding microbial homeostasis inoral entry. To investigate the impact of stress oninnate immunity and subsequent susceptibilityor resistance to oral or airway pathogens, it willlikely be informative to elucidate whether and howstress can or cannot be involved in the kinetics ofindividual local immune components.Our work has several limitations. First, thereis still certain amount of controversy over howthe measure of individual salivary contentshould be represented by absolute concentrationsor any corrected values, such as those for thesaliva flow rate (secretion rate) 5) . With regardto IgA data, the secretion rate is thought to givea more appropriate indication of the mucosalsurface barrier compared with the absolute IgAconcentration because the values corrected for thesaliva flow rate reflect the actual amount of IgAavailable for mucosal immunity 5) . The correctionsare all the more effective when decreases inthe saliva flow rate are observed. In the presentstudy, the saliva flow rate did not significantly,but tended to, decrease after the exercise session(P=0.0627), we thus presented the secretion rateas well as the absolute concentrations in saliva.In addition, corrected values for saliva osmolalityand total protein contents are also commonly usedfor expression of saliva IgA data 5) . In particular, inthe current study, the saliva osmolality and totalprotein levels in saliva were elevated during 60-min exercise compared with the resting session.Thus, we corrected the observed concentrationfor saliva osmotic pressure and total albuminlevels in saliva, and the changes in these correctedvalues seem quite similar to those in the absoluteconcentrations. Finally, we were unable toelucidate how the transient changes observed insalivary HBD-2 and LL-37 levels could affectthe overall antibacterial activity in saliva. In thepresent study, we focused only on the kinetics ofthese peptides and its association with changes insaliva cortisol levels as a result of physical stressby high-intensity exercise. Future studies willbe needed to examine the antimicrobial effectof exercise-induced changes in these salivarypeptides. However, it will be necessary to examinethe impact of psychological stress by assessingother psychological parameters.In summary, the results of the present studyshowed contrasting kinetics of HBD-2, LL-37,and IgA in saliva induced by a single bout ofstrenuous exercise. Furthermore, the transientrises in both HBD-2 and LL-37 levels wereinversely associated with increases in salivarycortisol levels and positively correlated to thosein plasma norepinephrine levels. Stress-inducedendocrinological changes by intense exercise? 237 ?