Short communication: renal tubular vacuolation in animals treated with polyethylene-glycol-conjugated proteins.
During toxicologic evaluation of a dimeric PEG-linked protein, tumor necrosis factor binding protein (TNF-bp), vacuolation of renal cortical tubular epithelium was seen in male and female Sprague-Dawley rats (200-300 g) given i.v. doses of 40, 20, or 10 mg/kg every other day for 3 months. Tubular lesions in rats treated with 20 or 40 mg/kg for 3 months were only partially reversible after a 2-month recovery period. Despite the presence of marked vacuolation, there were no changes in BUN, creatinine, urinalysis parameters, urinary NAG, urinary B2-microglobulin, or fractional sodium excretion. Single i.v. doses > or = 20 mg/kg TNF-bp caused similar but milder changes. However, equivalent doses of PEG alone or the non-PEG-linked TNF-bp did not cause light microscopic evidence of vacuolation. Treatment of rats with another PEG-linked protein of similar molecular weight resulted in similar changes. Immunostaining for TNF-bp revealed positivity in the apical cytoplasm of renal tubular epithelium within 1 h of i.v. dosing. Immunostaining of kidneys from chronically dosed rats indicated that protein was present in some vacuoles as long as dosing continued; however, kidneys from animals on a reversibility study had vacuoles but no immunostaining for TNF-bp. These results, along with a study that showed more severe lesions with PEG-linked proteins of lower molecular weight and minimal if any lesions with PEG-linked proteins > 70 kDa, suggest that TNF-bp is filtered through the glomerulus and that the protein with attached PEG is reabsorbed by the proximal tubules. Vacuolation may be a result of fluid distension of lysosomes due to the hygroscopic nature of PEG. These studies demonstrated that PEG-linked proteins have the capacity to induce renal tubular vacuolation at high doses. However, the change was not associated with alteration of clinical pathology or functional markers.
Bendele
A
A
Amgen Inc., Boulder, Colorado 80301, USA.
Seely
J
J
Richey
C
C
Sennello
G
G
Shopp
G
G
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000633:toxicity*; D005260:Female; D007684:Kidney Tubules / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D053319:Tumor Necrosis Factor Decoy Receptors; D014617:Vacuoles / Q000187:drug effects*
D002352:Carrier Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D053319:Tumor Necrosis Factor Decoy Receptors; C069521:recombinant human tumor necrosis factor-binding protein-1; D011092:Polyethylene Glycols