Eluate derived by extracorporal antibody-based immunoadsorption elevates the cytosolic Ca2+ concentration in podocytes via B2 kinin receptors

TY - JOUR

T1 - Eluate derived by extracorporal antibody-based immunoadsorption elevates the cytosolic Ca2+ concentration in podocytes via B2 kinin receptors

AU - Fischer, Karl-Georg

AU - Huber, Tobias Bruno

AU - Henger, Anna

AU - Fink, Edwin

AU - Schwertfeger, Eckhard

AU - Rump, Lars Christian

AU - Pavenstädt, Hermann

N1 - Copyright 2002 S. Karger AG, Basel

PY - 2002

Y1 - 2002

N2 - BACKGROUND/AIM: Patients with idiopathic focal segmental glomerulosclerosis (FSGS) often develop a recurrence of the disease after kidney transplantation. In a number of FSGS patients, plasmapheresis and immunoadsorption procedures have been shown to transiently reduce proteinuria and are thought to do this by eliminating a circulating factor. Direct cellular effects of eluates from immunoadsorption procedures on podocytes, the primary target of injury in FSGS, have not yet been reported.METHODS: Eluates were derived from antibody-based immunoadsorption of a patient suffering from primary FSGS, a patient with systemic lupus erythematosus, and a healthy volunteer. The cytosolic free Ca(2+) concentration ([Ca(2+)](i)) of differentiated podocytes was measured by single-cell fura-2 microfluorescence measurements. Free and total immunoreactive kinin levels were measured by radioimmunoassay.RESULTS: FSGS eluates increased the [Ca(2+)](i) levels concentration dependently (EC(50) 0.14 mg/ml; n = 3-19). 1 mg/ml eluate increased the [Ca(2+)](i) values reversibly from 82 +/- 12 to 1,462 +/- 370 nmol/l, and then they returned back to 100 +/- 16 nmol/l (n = 19). The eluate-induced increase of [Ca(2+)](i) consisted of an initial Ca(2+) peak followed by a Ca(2+) plateau which depended on the extracellular Ca(2+) concentration. The eluate-induced increase of [Ca(2+)](i) was inhibited by the specific B(2) kinin receptor antagonist Hoe 140 in a concentration-dependent manner (IC(50) 2.47 nmol/l). In addition, prior repetitive application of bradykinin desensitized the effect of eluate on [Ca(2+)](i). A colonic epithelial cell line not reacting to bradykinin did not respond to eluate either (n = 6). Similar to FSGS eluates, the eluate preparations of both the systemic lupus patient and the healthy volunteer led to a biphasic, concentration-dependent [Ca(2+)](i) increase in podocytes which again was inhibited by Hoe 140. Free kinins were detected in all eluate preparations.CONCLUSION: The procedure of antibody-based immunoadsorption leads to kinin in the eluate which elevates the [Ca(2+)](i) level of podocytes via B(2) kinin receptors.

AB - BACKGROUND/AIM: Patients with idiopathic focal segmental glomerulosclerosis (FSGS) often develop a recurrence of the disease after kidney transplantation. In a number of FSGS patients, plasmapheresis and immunoadsorption procedures have been shown to transiently reduce proteinuria and are thought to do this by eliminating a circulating factor. Direct cellular effects of eluates from immunoadsorption procedures on podocytes, the primary target of injury in FSGS, have not yet been reported.METHODS: Eluates were derived from antibody-based immunoadsorption of a patient suffering from primary FSGS, a patient with systemic lupus erythematosus, and a healthy volunteer. The cytosolic free Ca(2+) concentration ([Ca(2+)](i)) of differentiated podocytes was measured by single-cell fura-2 microfluorescence measurements. Free and total immunoreactive kinin levels were measured by radioimmunoassay.RESULTS: FSGS eluates increased the [Ca(2+)](i) levels concentration dependently (EC(50) 0.14 mg/ml; n = 3-19). 1 mg/ml eluate increased the [Ca(2+)](i) values reversibly from 82 +/- 12 to 1,462 +/- 370 nmol/l, and then they returned back to 100 +/- 16 nmol/l (n = 19). The eluate-induced increase of [Ca(2+)](i) consisted of an initial Ca(2+) peak followed by a Ca(2+) plateau which depended on the extracellular Ca(2+) concentration. The eluate-induced increase of [Ca(2+)](i) was inhibited by the specific B(2) kinin receptor antagonist Hoe 140 in a concentration-dependent manner (IC(50) 2.47 nmol/l). In addition, prior repetitive application of bradykinin desensitized the effect of eluate on [Ca(2+)](i). A colonic epithelial cell line not reacting to bradykinin did not respond to eluate either (n = 6). Similar to FSGS eluates, the eluate preparations of both the systemic lupus patient and the healthy volunteer led to a biphasic, concentration-dependent [Ca(2+)](i) increase in podocytes which again was inhibited by Hoe 140. Free kinins were detected in all eluate preparations.CONCLUSION: The procedure of antibody-based immunoadsorption leads to kinin in the eluate which elevates the [Ca(2+)](i) level of podocytes via B(2) kinin receptors.

KW - Bradykinin

KW - Calcium

KW - Cell Differentiation

KW - Cell Line

KW - Cytosol

KW - Female

KW - Glomerulosclerosis, Focal Segmental

KW - HT29 Cells

KW - Humans

KW - Immunosorbent Techniques

KW - Kidney Glomerulus

KW - Kidney Transplantation

KW - Kinins

KW - Lupus Nephritis

KW - Male

KW - Receptor, Bradykinin B2

KW - Receptors, Bradykinin

KW - Case Reports

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 68697

DO - 68697

M3 - SCORING: Journal article

C2 - 12590202

VL - 25

SP - 384

EP - 393

JO - KIDNEY BLOOD PRESS R

JF - KIDNEY BLOOD PRESS R

SN - 1420-4096

IS - 6

ER -