Effect of calorie-restriction and rapamycin on autophagy and the severity of caerulein-induced experimental acute pancreatitis in mice

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.

The Beneficial and Adverse Effects of Autophagic Response to Caloric Restriction and Fasting

Each cell is equipped with a conserved housekeeping mechanism, known as autophagy, to recycle exhausted materials and dispose of injured organelles via lysosomal degradation. Autophagy is an early-stage cellular response to stress stimuli in both physiological and pathological situations. It is thought that the promotion of autophagy flux prevents host cells from subsequent injuries by removing damaged organelles and misfolded proteins. As a correlate, the modulation of autophagy is suggested as a therapeutic approach in diverse pathological conditions. Accumulated evidence suggests that intermittent fasting or calorie restriction can lead to the induction of adaptive autophagy and increase longevity of eukaryotic cells. However, prolonged calorie restriction with excessive autophagy response is harmful and can stimulate a type II autophagic cell death. Despite the existence of a close relationship between calorie deprivation and autophagic response in different cell types, the precise molecular mechanisms associated with this phenomenon remain unclear. Here, we aimed to highlight the possible effects of prolonged and short-term calorie restriction on autophagic response and cell homeostasis.