Apoptosis and caspase-3 in experimental anti-glomerular basement membrane nephritis

The caspase family is central to the proteolytic events of apoptosis. In pa rticular, caspase-3 plays a key role in the execution of apoptosis. However , the importance of caspase-3 in renal cell apoptosis during kidney scarrin g has not been established. Here, nephrotoxic nephritis (NTN) was induced i n Wistar Kyoto rats by a single intravenous injection of rabbit anti-rat gl omerular basement membrane serum, with analysis at days 7, 15, 30, and 45 a fter injection. Cell apoptosis tin situ end labeling of DNA, light and elec tron microscopy), proliferation (proliferating cell nuclear antigen-positiv e cells), and inflammation (ED1-positive cells) all increased in NTN kidney s, peaking early (day 7) in the glomeruli and later (days 30 to 45) in the tubules and interstitium. The expression of caspase-3 mRNA (Northern blotti ng) was increased in NTN kidneys on days 7, 30, and 45 (173.3%, 228%, and 2 41.7%, respectively; P < 0.05). Western blotting showed that a 24-kD protei n band (caspase-3 active subunit) increased with time in NTN kidneys (P < 0 .01) and reached a maximum on day 45 (6.08-fold increase). A 32 kD band (ca spase-3 precursor) was also increased on day 45 (3.92-fold; P < 0.01). Elev ated caspase-3 activity (two- to threefold) was observed in NTN kidneys at all time points (P < 0.01). Upregulated expression of caspase-3 at all leve ls positively correlated with apoptosis, whereas both correlated closely wi th inflammation, proliferation, and subsequent fibrosis in glomeruli, tubul es, and interstitium (P < 0.05). Inhibition of caspase-3 during the course of experimental nephritis may offer a new therapeutic approach for the prev ention of renal apoptosis and the associated renal tubular atrophy and fibr osis.