Caspase-1, IL-1α, and IL-1β are known to be activated in the NLRP3
inflammasome. The
inflammasome is activated mostly in inflammatory cells. The presence of
inflammasome proteins in proximal tubules (PTs) and the effect of
cisplatin-treatment or
caspase inhibition on
inflammasome proteins in PTs are not known. The aim of this study was to investigate the effect of
cisplatin on
inflammasome proteins in freshly isolated PTs and also to determine the effect of
caspase inhibition on
inflammasome proteins and PT injury. PTs were isolated using
collagenase digestion and
Percoll centrifugation. After recovery period, freshly isolated PTs were incubated with vehicle, 50 µM
cisplatin or 50 µM
cisplatin plus 50 µM pan
caspase inhibitor,
QVD-OPH. PTs treated with 50 µM
cisplatin showed
Propidium Iodide staining indicative of
necrosis. Necrotic cells (%) were 2.2 in Vehicle-treated, 37.7 in
Cisplatin-treated (p < 0.05 vs. Vehicle), and 3.3 in QVD-treated (p < 0.05 vs.
Cisplatin). LDH release (%), a marker of cell membrane damage seen in
necrosis was 7.1 in Vehicle-treated, 39.7 in
Cisplatin-treated (p < 0.05 vs. Vehicle), and 13.5 in QVD-treated (p < 0.05 vs.
Cisplatin). Caspase-1 activity and active caspase-1
protein (10 kDa) were significantly increased in
Cisplatin-treated PTs. NLRP3 was strongly expressed in PTs, but there were no significant changes between groups. Pro-apoptotic BID (22 kDa) was unchanged between groups. IL-1α and IL-1β activity was increased in
Cisplatin-treated PTs.
QVD-OPH co-treatment decreased caspase-1, IL-1α, and IL-1β. In summary,
caspase inhibition decreases caspase-1, IL-1α, and IL-1β but not NLRP3 or
BID protein and protects against
necrosis in
cisplatin-treated freshly isolated PTs.