Adrenal cortical activation in murine colitis

Abstract

Background & Aims: Proper adrenal glucocorticoid secretion is crucial in the course of inflammatory diseases. However, the function and structure of the adrenal glands have not been examined in inflammatory bowel diseases. Methods: After induction of trinitrobenzene sulfonic acid (TNBS) colitis in SJL/J mice, plasma hormone and cytokine levels were measured, adrenal structure was analyzed by immunohistochemistry and electron microscopy, and adrenal cytokine/cytokine receptor expression were studied by RNase protection. Results: Adrenals of colitic animals were enlarged and hypervascularized. These animals had a marked increase in plasma corticosterone levels during the course of colitis (270 ± 34 vs. 16 ± 11 ng/mL; P < 0.0001) but only a modest elevation of their concurrent adrenocorticotropin levels (57 ± 13 vs. 29 ± 9 pmol/L; NS). On electron microscopy, adrenocortical cells showed ultrastructural signs of marked stimulation, and intra-adrenal lymphocytes were frequently found in direct contact with these cells. Concurrent plasma levels of interleukin (IL)-6, the major cytokine activating the hypothalamic-pituitary-adrenal axis, were markedly increased (495 ± 131 vs. 20 ± 1.5 pg/mL; P < 0.0001), and this cytokine directly stimulated corticosterone secretion by adrenocortical cells in vitro. Intra-adrenal expression of IL-6 in animals with colitis was increased 80-fold, and the IL-6 receptor subunits IL-6Rα and gp130 were present in the adrenal cells. Treatment of animals with neutralizing anti-IL-6 antibody reduced the TNBS-induced growth and activation of the adrenal cortices. Conclusions: Colitis is associated with a profound stimulation of adrenocortical cell function and glucocorticoid release. Direct immune-adrenal interactions seem to contribute to this activation of the adrenal glands during colitis.