Effect of chloroquine on autophagy and the severity of caerulein-induced acute pancreatitis in mice.

Impaired autophagy is implicated in the pathogenesis of caerulein-induced model of acute pancreatitis (AP). Chloroquine blocks the fusion of autophagosome and lysosome and affects completion of the cellular autophagic flux. Adult, male, Swiss albino mice (20-25 g) were divided into four groups- 1, 2, 3 and 4 of 6 mice each. Mice in Group1 were given 8, hourly intraperitoneal injections of normal saline. Group 2 was also given intraperitoneal injections of chloroquine (60 mg/Kg) at 14 h and 30-min prior to first injection of normal saline. Mice in Groups 3 and 4 given 8, hourly intraperitoneal injections of caerulein (50 µg /Kg/dose). Group 4 also received chloroquine as Group 2. After sacrifice at the 9th hour in CO2-chamber, blood was drawn for amylase activity and cytokines estimation (IL-6, TNF-α, GM-CSF, IL-1β and IL-10) and pancreas was harvested for histopathology, transmission electron microscopy (TEM) and immunoblotting (LC3II, Beclin 1, SQSTM1, RIPK1, P65, Caspase-3, RIPK3, HMGB1). The relative expression of SQSTM1 and the autophagic vacuole area was higher in groups 2, 3 and 4 (p < 0.05), suggestive of increased impairment of autophagic flux. Autolysosome count was significantly increased in group 3 in comparison to group 1 (p = 0.0049). Autolysosome area was also increased in group 4 in comparison to group 3 (p = 0.031), which suggested impairment of autophagy. Total histopathological score and amylase activity were equivalent in groups 3 and 4. RIPK1 in pancreas and TNF-α level in plasma were more in group 4 than 3 (p = 0.014, 0.02, respectively). Expression of Caspase-3, was lesser in group 4 than 3 (p < 0.001). Expression of HMGB1was more in group 4 than 3 (p = 0.046). Chloroquine enhances necrosis and inflammation in caerulein-induced pancreatitis.