Tumor Necrosis Factor-alpha (TNFα) receptor type 1 (TNFR1) activation during severe inflammation; Can it be a therapeutic target in hypervolemic hyponatremia?

Abstract

Hyponatremia is a life-threatening situation in severe inflammatory disorders. Managing this disorder is seriously hampered because its underlying pathophysiology has remained elusive. An increase in tumor necrosis factor-alpha (TNFα) during systemic inflammation may be involved in this hyponatremic mechanism as it is known that circulating TNFα exerts potent natriuresis via its action on receptor type 1 (TNFR1). Systemic inflammation also induces non-osmotic release of Antidiuretic Hormone (ADH), commonly known as ‘Syndrome of Inappropriate ADH’ (SIADH), that would cause water retention to increase in Extracellular Fluid Volume (ECV). Thus, the inflammation-induced TNFR1 activation and sodium loss coupled with SIADH-induced increases in ECV, would lead to the serious condition of hypervolemic hyponatremia. In this brief review, some experimental evidence will be provided that indicates TNFR1 activation during the inflammatory process can be targeted therapeutically to prevent such critical conditions of hypervolemic hyponatremia. The importance of these co-morbidities also extends to several other clinical scenarios of hyponatremia observed in patients with heart failure, liver disease, and renal disease. Besides the pathophysiological insights, the recognition of the propensity for both antidiuresis and natriuresis during inflammation is critically important in selecting the appropriate intravenous fluid regimens in patients with this disorder such as in the coronavirus disease of 2019 (COVID-19).