Perturbations of cell interactions, an carly event in acute renal injury, have important pathophysiologic consequences. We hypothesized that promotion of cell interactions protects cells from injury. To test this hypothesis, a single cell suspension of LLC-PK1 cells (porcine proximal tubular cell line) treated with albumin (control) was compared to cells aggregated with fibrinogen or purified human clusterin (aggregation graded 0 to 4). Following aggregation, the cells were injured with 1.5 mM hydrogen peroxide (H2O2) for three hours. Cell aggregation induced by clusterin but not fibrinogen protected against oxidant injury by H2O2. Complete abrogation of cytotoxicity occurred at a clusterin concentration of 2.5 μg/ml, which resulted in an aggregation score of 1. In the absence of aggregation, clusterin at concentrations of 20 and 50 μg/ml, but not lower doses, partially protected against injury induced by H2O2. Cell aggregation induced by both clusterin and fibrinogen partially protected against endogenously generated oxidant stress induced by incubating LLC-PK1 cells with aminotriazole and 1-chloro-2,4-dinitrobenzene (CDNB). In conclusion, clusterin protects against models of oxidant stress in vitro, whether generated by exogenously administered hydrogen peroxide, or from endogenously produced peroxide, and such protective effects can accrue from aggregative and nonaggregative properties of clusterin.
Bibliographical noteFunding Information:
This work was supported by US Public Health Service Grants RO-1 48452 (M.E.R), DK47060 (K.A.N.) and a National Research Service Award (G.B.S.); and the Baxter Extramural Grant Program. This work was done during the tenure of an Established Investigatorship from the American Heart Association (M.E.R.). Part of this work was presented and at the 1996 American Society of Nephrology meeting in New Orleans, LA. The anti-human clusterin antibody was a gift of Brendan Murphy, Melbourne, Australia.
- Cell interactions
- Oxidant injury