Macrophage pacification reduces rodent pancreatitis-induced hepatocellular injury through down-regulation of hepatic tumor necrosis factor ? and interleukin-1?

Abstract

Overproduction of tumor necrosis factor α (TNF‐α), interleukin‐1β (IL‐1β), and nitric oxide (NO) is believed to be detrimental during the progression of acute pancreatitis, yet little is known about the hepatic production of these mediators and their role in mediating pancreatitis‐induced hepatic dysfunction. Rats were randomized to receive a single intraperitoneal injection of the macrophage‐pacifying compound, CNI‐1493 (1.0 mg/kg), or vehicle 1 hour before the induction of retrograde bile salt pancreatitis. Sham‐operated animals served as controls. Animals were killed 18 hours later, with serum and livers harvested to determine the degree of hepatocellular injury and the induction of TNF‐α, IL‐1β, and inducible nitric oxide synthase (iNOS). In addition, serum TNF‐α and nitrites (end‐product of NO breakdown) were determined in each group to assess the mechanism of action of CNI‐1493. TNF‐α, IL‐1β, and iNOS gene expression (by reverse‐transcription polymerase chain reaction) as well as aspartate transaminase (AST), alanine transaminase (ALT), and lactic dehydrogenase (LDH) (but not alkaline phosphatase [ALP]) increased following the development of pancreatitis (all P < .05). Macrophage pacification significantly prevented the induction of TNF‐α and IL‐1β mRNA (but not iNOS), resulting in lessened serum AST, ALT, and LDH (all P < .05). Serum TNF‐α protein and nitrites correlated with gene induction in that both were increased following the onset of pancreatitis, and TNF‐α protein production was significantly attenuated in animals receiving CNI‐1493. Hepatocellular, but not bile duct, injury occurs during experimental pancreatitis that is associated with hepatic TNF‐α, IL‐1β, and iNOS mRNA gene induction, as well as TNF‐α protein and nitrite production. Preventing the production of TNF‐α and IL‐1β by macrophage pacification attenuates the hepatocellular damage, suggesting that these mediators play a role in pancreatitis‐induced hepatic injury.