The effect of interleukin-6 on bacterial translocation in acute canine pancreatitis

Background. Bacterial translocation from the gut to mesenteric lymph nodes and other extraintestinal sites is an important source of infection in acute pancreatitis. Impaired host immunity is known to promote bacterial translocation. Interleukin-6 (IL-6) is a multifunctional cytokine that regulates the immune response, acute phase reaction, and hematopoiesis. Methods. Twenty-four mongrel dogs (18-29 kg) were studied in four equal groups: In Groups I and II, acute pancreatitis was induced by direct pressure injection of 4% taurocholate and trypsin into the pancreatic duct at laparotomy. Groups III and IV had only laparotomy. Group I and III dogs were given IL-6 (50 μg/kg/d, sq) daily starting 24 h after operation and Group II and IV dogs received an equal volume of saline administered at similar time. All animals had blood drawn for culture, complete blood count (CBC), platelets, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and amylase on d 0, 1, 4, and 7. On d 7, mesenteric lymph nodes (MLN), spleen, liver, pancreas, and cecum were harvested for pathology study and for cultures of aerobic and anaerobic bacteria. Quantitative cecal cultures of aerobic and anaerobic bacteria were obtained. Results. All Group I and Group II dogs had severe pancreatitis. The increase of plasma CRP in Group I was sustained throughout treatment (1.3 ± 0.3 on d 0 vs 3.1 ± 0.3* 3.0 ± 0.3* and 2.9 ± 0.3* on d 1,4, and 7, respectively). Plasma CRP was increased in Group II on d 1 and d 4 (1.3 ± 0.3 mg/dL on d 0 vs 3.6 ± 0.3* mg/dL on d 1, and 3.1 ± 0.3* on d 4, *p < 0.05). There were no differences in white blood cell (WBC) count, differential, platelets, and ESR between Groups I and II. Bacterial translocation to MLN was lower in Group I (1/6) than in Group II (6/6) (p < 0.05). All 6 dogs in Group II had bacterial spread to distant sites compared to 2 of 6 dogs in Group I (p = 0.066). Both MLN and other distant organ cultures were negative in Group III and only I of 6 MLN cultures was positive in Group IV. Conclusions. IL-6 treatment decreases bacterial translocation to MLN and may be beneficial in reducing septic complications in acute pancreatitis.