TLR4 regulation of pancreatic tumorigenesis and pancreatitis is mediated by stromal inflammatory cells and requires TRIF. (A and B) p48Cre;Kras^G12D mice were irradiated and made chimeric by bone marrow transfer from WT or TLR4^−/− mice. 7 wk later, mice were treated with either saline or two doses of caerulein (C). Three weeks afterward, mice were sacrificed and pancreata were assessed by H&E. The fraction of dysplastic ducts was measured (n = 5/group; ***, P < 0.001). Insets show higher magnification. (C) WT chimeric and TLR4^−/− chimeric mice were treated with 5 µg LPS. Serum cytokine levels were measured at 6 h (***, P < 0.001). (D) WT or TLR4^−/− mice were adoptively transferred with intrapancreatic Kras^G12D PDECs. Pancreata were harvested and weighted at 6 wk (n = 5 mice/group; ***, P < 0.001). (E) Raji cells were stimulated for 90 s with 1 µg/ml LPS in the presence of TRIF inhibitor (Pepinh-TRIF) or control peptide (Pepinh-Ctl). Expression of pIRF3 and β-actin was measured by Western blotting. (F) 4-wk-old p48Cre;Kras^G12D mice were treated with saline, caerulein + control peptide, or caerulein + TRIF inhibitor. Representative H&E-stained sections are shown, and the number of dysplastic ducts per HPF was calculated (n = 5 mice/group; ***, P < 0.001). (G) WT or TRIF^−/− mice were adoptively transferred with intrapancreatic Kras^G12D PDECs. Pancreata were harvested and weighted at 6 wk (n = 4–5 mice/group; ***, P < 0.001). (H) Acute pancreatitis was induced using caerulein in WT or TRIF^−/− mice. The fraction of viable acini was calculated (n = 4 mice/group; ***, P < 0.001). (I) 4-wk-old p48Cre;Kras^G12D mice were treated with saline or Poly I:C before sacrifice 4 wk later. Representative H&E-stained sections are shown, and the number of PanIN lesions per HPF was quantified (n = 4 mice/group; ***, P < 0.001). Error bars indicate standard error of the mean.