Abstract
Immunogenetic mechanisms operating within the immune system are known to influence cytokine profiles and disease susceptibility. Yet the role of the individual's neurohormonal background in these processes remains undefined. Hormonal imbalances are documented in immune-related diseases, but it is unclear whether this represents a secondary phenomenon or a primary "defect" related to specific neurohormonal immune phenotype(s). We report that in a large subpopulation of healthy humans the baseline epinephrine output (but not cortisol and sex steroid hormones) correlated inversely with proinflammatory and positively with anti-inflammatory cytokine production. Thus, low vs high epinephrine excretors had a 2- to 5-fold higher TNF-alpha and IL-12 production but 2-fold lower IL-10 production induced by LPS ex vivo. In alternative settings, we found low baseline levels and profoundly blunted stress-induced epinephrine responses but high TNF-alpha levels in Lewis vs Fischer inbred rats. Additionally, isoproterenol, a beta adrenoreceptor agonist suppressed LPS-induced TNF-alpha production, with more pronounced effect in Lewis than in Fischer rats. In human monocytes, epinephrine and the beta(2) adrenoreceptor agonist fenoterol potently inhibited LPS-induced TNF-alpha and IL-12, but stimulated IL-10 production. The order of potency for hormones able to inhibit IL-12 production ex vivo was: epinephrine > norepinephrine > or = 1,25-(OH)(2) vitamin D(3) > hydrocortisone. This indicates that baseline epinephrine conditions cytokine responsiveness and through this mechanism intrinsic hypo- or hyperactive adrenal medullas in some individuals may shape opposite cytokine profiles. Since Lewis and Fischer rats have opposite susceptibility to experimental immunological diseases, this suggests that the parallel human phenotypes could be linked to differing responsiveness and susceptibility to infections and immune/inflammatory-related conditions.