Thiol-inducing and immunoregulatory effects of flavonoids in peripheral blood mononuclear cells from patients with end-stage diabetic nephropathy.
The cellular thiol status and its relationship to T-cell activation and cytokine synthesis of mononuclear cells was investigated in patients with end-stage diabetic nephropathy (ESDN) undergoing dialysis treatment. The functional effects of thiol repair by in vitro and in vivo treatment with flavonoids were elucidated. The thiol status of peripheral blood lymphocytes from 30 ESDN patients on hemodialysis and healthy controls was determined by flow cytometry. T-cell activation in response to pokeweed mitogen was analyzed by CD69 expression; cytokines were determined in cell culture supernatants. In result, compared to age-matched healthy subjects, a significant thiol deficiency in ESDN patients was obvious. The lowered total intracellular thiol levels correlated directly to a significant diminished T-cell activation and an elevated synthesis of TNF-alpha in the patient group. The treatment with flavonoids led to a restoration of the thiol status within 72 h in vitro and in vivo. This effect showed a biphasic kinetic that first utilized cell surface thiols and secondly intracellular thiols. In parallel, the T-cell activation was improved substantially along with a significant decrease in TNF-alpha release. These data provide the rational for clinical trials using flavonoids in ESDN to normalize immunoregulatory defects via restoration of the cellular thiol status.