TNF MEDIATES A MURINE MODEL OF ADDISONʼS CRISIS

Abstract
Addison's crisis is the most serious complication of adrenal insufficiency. To elucidate the mechanism of this disorder following infection, the role of TNF in adrenalectomized murine models of Addison's crisis and Addison's disease (chronic hypoglucocorticoidism) were examined. Adrenalectomy conferred a 40-fold increased sensitivity to the lethal effects of lipopolysacharride (LPS) (P < .001). Enhanced sensitivity to LPS was found to increase with duration of adrenal insufficiency (P < .02). Enhanced lethality to heat-killed Streptococcus pneumonia was also demonstrated (P < 0.02). Necropsy of endotoxinkilled adrenalectomized mice demonstrated similar pathologic findings to those found by others when the control mice were administered a lethal dose of either LPS or TNF. Adrenalectomized TNF receptor la and lb double null mice were demonstrated to be resistant to the lethal effects of LPS (P < 0.02). Pretreatment with anti-TNF, but not control antisera, was found to prevent death in LPS-treated wild-type adrenalectomized mice as well (P < 0.02). Studies into the mechanism by which TNF was precipitating Addison's crisis demonstrated enhanced sensitivity to TNF (3-fold; P < 0.02), and a marked increase in serum TNF concentration (approximately 5-fold; P < 0.001) following LPS challenge. The effect of TNF upon long-term survival in adrenalectomized mice was examined in TNF-receptor la- and lb-deficient mice. Deficiencies in either the TNF-receptor la or lb was noted to confer a survival advantage relative to colony controls following adrenalectomy (P < 0.02). In summary, both LPS-induced Addison's crisis and chronic adrenal insufficiency are disorders of TNF disregulation. Based upon these data, therapeutic strategies targeted at controlling TNF in adrenal insufficiency are suggested.

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