TNFalpha exerts its functions by engaging two receptors (TNF-RI and TNF-RII). The extracellular parts of the receptors are proteolytically shed to the soluble forms by a matrix metalloproteinase-like enzyme (sTNF-RI and sTNF-RII). The soluble TNF receptors can neutralize TNFalpha activities. Circulating levels of both sTNF-RI and sTNF-RII are elevated in patients with congestive heart failure (CHF). It remains unclear how a large amount of sTNF-RI and sTNF-RII is mobilized into the circulation. Mononuclear leukocytes were obtained from 14 controls and 21 patients with CHF. TNF-RII of the cells from CHF patients was upregulated in the cell-surface expression and mRNA transcripts. Besides enhanced shedding of TNF-RII on the cells from CHF patients with phorbol myristate acetate (PMA), sera from CHF induced shedding of TNF-RII on the cells from normal volunteers. Thus, the enhancement of both expression and shedding of TNF-RII may be related to increased circulating levels of the soluble TNF receptor in patients with CHF. The presence of CHF may affect the regulation of TNF receptors, which may modulate the responsiveness to TNFalpha in the tissues of patients with CHF.
Copyright 1998 Academic Press