Caerulein

Pancreatic injury was induced on young KC mice (8–12 weeks old) by a series of six hourly intra‐peritoneal injections of caerulein (75 µg/kg of body weight, Bachem) repeated after 48 h. Eight days later, a treatment/intervention protocol was developed to allow formation of pre‐cancer lesions: mice were treated with the vehicle (0.5% methyl cellulose with 0.2% Tween‐80) or with GDC0326 (10 mg/kg) by gavage (Appendix Fig S16A).

Pancreatitis was induced in 4 week old adult mice by eight hourly intraperitoneal injections of 0.1 μg/g caerulein (Bachem Americas, Inc., Torrance, CA) for 2 days (i.e. day − 1 and day 0)^{54 (link)}. Mice were sacrificed at 2, 4, 7, and 14 days post caerulein injections. Bulk RNAseq was prepared from pancreata isolated at day 2, day 4, and day 7 following caerulein treatment. RNAseq analyses were perform as described previously^{55 (link)}.

Two to three-month-old mice were administered eight hourly intraperitoneal injections per day of saline control or 100 µg/kg caerulein (Bachem) over 2 consecutive days for 16 injections total. Mice were euthanized at day 2, 4, or 7 after injections, and the pancreas and blood were collected for analysis.

Doxycycline hyclate BioChemica (PanReac, 234-198-7, A2951) was administered in the drinking water (1 mg/ml) supplemented with 7.5% sucrose for 7 days. Immune populations were depleted by intraperitoneal injection of 200 μg of anti-NK1.1 (Bio X Cell, clone PK136) or 200 μg of anti-Gr1 (Bio X Cell, clone RB6-8C5) on days −1, 3 and 5 of reprogramming. Isotype controls IgG2a (Bio X Cell, clone C1.18.4) and IgG2b (Bio X Cell, clone LTF-2) were used in control groups, respectively. For the depletion of Mφ, mice were treated with 200 μl of either clodronate or empty liposomes (Liposoma BV, CP-010-010) retro-orbitally on days 1, 3 and 6 of reprogramming. Mild acute pancreatitis was induced by seven intraperitoneal injections, given once per hour, of a pancreatic secretagogue cholecystokinin (CCK) analogue called caerulein (Bachem, 40304510001) at 100 μg/kg for 2 consecutive days. A second group of control animals received injections of PBS only. Mice were sacrificed on day 4 after the first injection. All animals were sacrificed by cervical dislocation, unless blood extraction from the heart was performed. In that case, mice were sacrificed in a CO₂ chamber.

Caerulein (#H-3220) was obtained from Bachem (Switzerland). Stock Caerulein solution (0.5 mg/ml) was prepared in sterile water and stored at −20 °C until use. Working Caerulein solution was prepared freshly on each injection day in 0.9% NaCl solution to make a 10 μg/ml solution. Repetitive episodes of pancreatitis (three episodes per week, i.e. Monday, Wednesday and Friday, over two weeks) were induced in animals with each episode consisting of six hourly injections (50 μg/kg) on each experiment day. Control groups received 0.9% NaCl solution.