Effects of seasonal changes on T-helper 1/T-helper 2 immune balance and eczema onset in rats

摘要

Objective:To explore the impact of seasonal changes on the T-helper 1(Th1)/T-helper 2(Th2)immune balance of the body in order to elucidate the internal immunological mechanisms underlying seasonal eczema.Methods:Eighty 4-week-old male SpragueeDawley rats were divided into 5 season groups kept in corresponding season simulation environments,and subdivided into the model group and the control group.The Eczema Area and Severity Index(EASI)and scratching frequency were evaluated.The serum levels of immunoglobulin E(IgE),interleukin-2(IL-2),interleukin-12(IL-12),and interferon-gamma(IFNg),interleukin-4(IL-4),interleukin-25(IL-25),and interleukin-31(IL-31),and melatonin(MT),as well as the MT receptor(MTR)levels in the spleen,were detected by enzyme-linked immunosorbent assay analysis.The mRNA expression levels of T-bet and GATA3 were detected by quantitative real-time polymerase chain reaction.Results:EASI scores and the scratching frequency of themodel groupwere higher in the long summer than in the other 4 seasons.Meanwhile,the serumlevels of IgE and the Th2 cytokines IL-4,IL-25,and IL-31,aswell as GATA3mRNAexpressionlevels,were high during the long summer inboth groups.However,the serumlevels of the Th1 cytokines IL-2,IL-12,and IFN-g,aswell asMT,MTR,and T-betmRNA levels,were lower during the long summer.In all 5 seasonal groups(spring,summer,long summer,autumn,and winter),the levels of all immune factors,especially IL-4 and IL-31,were higher in the model group than those in the control group,while the concentrations of MT and MTR were lower.Conclusion:Under long light,hot,and humid conditions in the long summer,the body ismore likely to suffer from Th2-dominated immune imbalance.This is the internal mechanism behind the high incidence and severity of eczema during the long summer.MT and MTR play a key role in the seasonal onset of eczema.