Aging leads to impaired epicutaneous sensitization that causes attenuated allergy and pulmonary inflammation in mice

Aging is associated with altered decreased barrier function in the skin, which can lead to different types of immunoglobulin E (IgE)-mediated sensitization to environmental allergens. Yet, allergen-specific respiratory sensitization among the elderly is not well described. The aim of this study was to investigate the effect of aging on allergic pulmonary inflammation induced by epicutaneous sensitization of mechanically irritated skin in mice. For this purpose, 6-week-, 6-month-, and 18-month-old female BALB/c mice, underwent epicutaneous sensitization with ovalbumin (OVA) or phosphate buffered saline (PBS), followed by an inhaled OVA challenge. Blood OVA-specific IgE levels measured after epicutaneous sensitization, as well as, bronchial alveolar lavage fluids (BALF) leucocyte, eosinophil, and cytokine levels measured after OVA inhalation challenge were similar among the 6-week-old (young) and 6-month-old (adult) groups. However, significantly decreased levels of systemic OVA IgE, and BALF leukocyte, eosinophil and T helper cell type 2 cytokine levels, were measured after OVA inhalation challenge in elderly (18-month-old) mice compared to the other groups of mice. In addition, interleukin-10 (IL-10), a regulatory suppressor cytokine, was more abundant in the BALF of the elderly group after epicutaneous sensitization and inhalation challenge. Our results suggest that elderly mice have a reduced allergic response to induced sensitization with OVA, possibly regulated by increased IL-10 levels.