Immunological dysregulation of lung cells in response to vitamin E deficiency

Abstract

Vitamin E supplementation exhibits anti-inflammatory properties. In the lung, the beneficial effects of vitamin E supplementation on inflammation and infections are well documented, but potential consequences of alimentary vitamin E deficiency to the immunological status of lung cells are not known. It is unclear if temporary vitamin E deficiency exhibits deleterious consequences or can be compensated for by other cellular antioxidants. To address this question, the alimentary vitamin E supply to rats was modified. We then investigated the effects on major histocompatibility molecule (MHC) class II, cell adhesion molecules, interleukin (IL)10, tumor necrosis factor (TNF)α in various lung cells. The constitutive expression of MHC class II, intercellular adhesion molecule (ICAM)-1, L-selectin, α5-integrin, and CD 166, was demonstrated by flow cytometry on type II pneumocytes, alveolar macrophages, and on co-isolated lymphocytes. Vitamin E depletion increased ICAM-1 and CD166 on type II cells and macrophages, whereas the expression of L-selectin increased only on macrophages. Furthermore, the vitamin E depletion increased the cellular content and secretion of IL10 in type II cells, but decreased the content and secretion of TNFα. Vitamin E depletion decreased the cellular vitamin E content, but did not change the activity of antioxidant enzymes (catalase, superoxide dismutase) and the glutathion (GSH)/oxidized glutathion (GSSG) ratio in alveolar type II cells. The shift of protein kinase C (PKC) from the cytosol to membranes indicates that a PKC-dependent signaling pathway may be involved in the change of the immunological status of type II cells. All these effects were reversed by vitamin E repletion. In summary, these results are clearly compatible with the view that a temporary vitamin E deficiency induces a reversible immunological dysregulation in alveolar type II cells and lung macrophages. This deficiency might predispose the lung to develop acute or chronic inflammation.