It has been previously shown that the two forms of acute cholecystitis, acute acalculous cholecystitis (AAC) and acute calculous cholecystitis (ACC), have significantly different histopathological features suggesting that AAC is a manifestation of systemic critical illness whereas ACC is a local disease of the gallbladder. A balance between cell proliferation and cell death is essential for cell homeostasis. The purpose of this study was to compare the markers of apoptosis, cell proliferation, and expression of hypoxic-inducible factor alpha (HIF-1α) in AAC, ACC and normal gallbladders.

The AAC group consisted of 30 patients who underwent open cholecystectomy due to acute acalculous cholecystitis during their ICU stay. The ACC group consisted of 21 hospitalized patients who underwent cholecystectomy due to acute calculous cholecystitis. The control group consisted of nine samples taken from normal gallbladders extirpated during pancreatic tumor surgery. The immunohistochemical analysis was done according to the manufacturer's recommendations and they consisted of Ki-67 (proliferation), M30 (apoptosis) and HIF-1α antibodies. Cell proliferation and degree of apoptosis were expressed as the percentage of positive cells. HIF-1α expression was expressed as absent or weak (Score 1) or strong (Score 2).

Apoptosis (median, 25th, 75th percentiles) was significantly increased in AAC 1.3% (1.0%, 3.3%), P = 0.001 and ACC 0.93% (0.40%, 3.25%), P = 0.011 compared with controls 0.32% (0.20%, 0.40%). Proliferation rate was also significantly increased in AAC 8.0% (4.0%, 17.0%), P < 0.001 and ACC 14% (7.5%, 26.5%), P = 0.001 compared with controls 1.0% (1.0%, 3.0%). Strong HIF-1α staining was observed in 100% of ACC, in 57% of AAC and in 44% of control specimens (P < 0.001). Strong HIF-1α expression was associated with increased cell proliferation (P = 0.002).

Cell proliferation and apoptosis were increased in AAC and ACC. The expression of hypoxic-inducible factor was, however, stronger in ACC compared with AAC.