Effect of early and late antibiotic treatment in experimental acute pancreatitis in rats

Carbachol protects the intestinal barrier in severe acute pancreatitis by regulating Cdc42/F-actin cytoskeleton

The present study aimed to investigate the effect of carbachol on the intestinal tight-junction barrier in a rat model of severe acute pancreatitis (SAP) without aggravating pancreatic injury, and to determine whether cell division cycle 42 (Cdc42)/F-actin could have a regulatory role. Rats were separated into a sham-operation (SO) group (n=10), SO + carbachol group (n=10), SAP group (n=60) and SAP + carbachol group (n=60). Sodium taurocholate (5%) was retrogradely injected into the biliopancreatic duct of rats to induce SAP. Subsequently, 16S rRNA sequencing was used to detect bacterial translocation (BT) in the gut of surviving animals. Hematoxylin and eosin staining was used to detect morphological changes in the pancreas and intestine. The expression of F-actin and tight junction proteins was analyzed by western blotting and immunofluorescence, and Cdc42 expression was analyzed by immunohistochemistry and western blotting. The results demonstrated that the intestinal injury in SO and SO + carbachol groups was lower than that in the SAP + carbachol group (P<0.05); however, the intestinal injury was similar in the SO and SO + carbachol groups (P>0.05), and was significantly more severe in the SAP group compared with the SAP + carbachol group (P<0.05). Similarly, pancreatic injury in the SAP and SAP + carbachol groups was significantly higher compared with the SO and SO + carbachol groups (P<0.05); however, pancreatic injury was similar in the SAP and SAP + carbachol groups (P>0.05), and in the SO and SO + carbachol groups (P>0.05). Furthermore, the mortality rate and BT in the SAP group were significantly higher compared with the SAP + carbachol group (mortality rate, 50% vs. 30%, P<0.05; BT, 60% vs. 33.3%, P<0.05). In addition, the expression of Cdc42, F-actin and claudin-2 was significantly higher in the SAP and SAP + carbachol groups compared with the SO and SO + carbachol groups (P<0.05), and the expression of occludin and zonula occludens-1 were significantly higher in the SO and SO + carbachol groups compared with the SAP and SAP + carbachol groups (P<0.05). In conclusion, these findings demonstrated that carbachol may protect the intestinal barrier in the SAP rat model without aggravating pancreatic injury via regulation of Cdc42/F-actin expression.

Infected pancreatic necrosis increases the severity of experimental necrotizing pancreatitis in mice

OBJECTIVE

Infection of pancreatic necrosis in necrotizing pancreatitis increases the lethality of patients with acute pancreatitis. To examine mechanisms underlying this clinical observation, we developed and tested a model, in which primary infection of necrosis is achieved in taurocholate-induced pancreatitis in mice.

METHODS

Sterile necrosis of acute necrotizing pancreatitis was induced by retrograde injection of 4% taurocholate into the common bile duct of Balb/c mice. Primary infection of pancreatic necrosis was induced by coinjecting 10 colony-forming units of Escherichia coli. Animals were killed after 6, 12, 24, 48, and 120 hours, and pancreatic damage and pancreatitis-associated systemic inflammatory response were assessed.

RESULTS

Mice with pancreatic acinar cell necrosis had an increased bacterial concentration in all tissues and showed sustained bacteremia. Acute pancreatitis was induced only by coinjection of taurocholate and not by bacterial infection alone. Infection of pancreatic necrosis increased pancreatic damage and the pulmonary vascular leak. Serum glucose concentrations serving as a parameter of hepatic function were reduced in mice with infected pancreatic necrosis.

CONCLUSIONS

Primary infection of pancreatic necrosis with E. coli increases both pancreatic damage and pulmonary and hepatic complications in acute necrotizing pancreatitis in mice.

Establishment of a secondary infection model of severe acute pancreatitis in swine

OBJECTIVE

Develop a swine model of secondary infection in severe acute pancreatitis (SAP).

METHODS

Twenty-seven female swine were divided into 3 groups (1-3). In the first experiment, a SAP model was developed by retrograde injection of sodium taurocholate and trypsin into the pancreatic duct. In the second experiment, the SAP model was used to develop a secondary infection model. In groups 1 to 3, 10⁸/mL or 10⁴/mL Escherichia coli or saline were respectively used to inoculate necrotic areas of the pancreas using computed tomographic guidance. Biochemical, histopathological, and imaging analyses were used to characterize disease presentation.

RESULTS

The survival rate was 85.2% (23/27) during the course of the 9-day experiment. The secondary infection rates in groups 1 to 3 were 100% (8/8), 37.5% (3/8), and 14.3% (1/7), respectively. In group 1, the infection rate was significantly higher in comparison to the other 2 groups (χ²=4.66 and 8.14, respectively, and both P<0.05). The biochemical and histopathological parameters and computed tomographic images indicated successful development of the SAP secondary infection model.

CONCLUSIONS

The swine model of SAP secondary infection was successfully developed using a 2-step method, which could serve as a platform for SAP studies that need complex experimental manipulations for longer time spans, especially for imaging research.

The use of antibiotics for acute pancreatitis: is there a role?

Infections due to pancreatic necrosis and abscesses are observed in one third of patients with severe acute pancreatitis (SAP). Based on results of double-blind, randomized, placebo-controlled trials, antibiotic prophylaxis in SAP is ineffective for reducing the frequency of infected necrosis and to decrease hospital mortality. Antibiotic treatment using carbapenems and quinolones is indicated on demand in patients with SAP and multiorgan failure at admission and in those with hemodynamic shock. Patients with biliary acute pancreatitis (AP) and clinically acute cholecystitis and/or cholangitis benefit from antibiotic treatment. Patients with AP associated with bacteremia, positive bronchoalveolar lavage, and urinary tract infection should receive antibiotics. In necrotizing pancreatitis, evidence-based data do not support late use of antibiotic prophylaxis after onset. Further high-quality, randomized, controlled trials are needed to evaluate antibiotic prophylaxis in the first 24 to 48 hours after SAP onset.

A role for prophylactic antibiotics in necrotizing pancreatitis? Why we may never know the answer

The use of prophylactic antibiotics in patients with severe acute pancreatitis remains an intensely debated topic. Although animal studies consistently demonstrated an advantage of antibiotic prophylaxis, the only two blinded randomized controlled trials could not confirm these findings. Translation of the experimental models in human clinical practice is hampered by a number of fundamental differences between experimental pancreatitis and human disease, and therefore it is highly unlikely that the pronounced benefit found in experimental pancreatitis will ever be demonstrated in human disease. Early and accurate risk stratification to identify the patient at risk for infection early in the course of the disease seems to be the greatest challenge. Until we are able to demonstrate an advantage of antibiotic prophylaxis in a high-risk human population, the absence of proven benefit and potential side effects of this strategy should be acknowledged and the use of antibiotics should be limited to the treatment of documented infection.

Prophylactic use of antibiotics in treatment of severe acute pancreatitis

Necrotic pancreatic infection is the most serious complication of severe acute pancreatitis (SAP). Although prophylactic antibiotics are widely used to reduce its death rate, its practical efficiency still remains controversial. Therefore, the clinical experiences with prophylactic use of antibiotics are summarized in this paper, hoping to offer certain guides to its treatment. However, results from recent studies do not support prophylactic use of antibiotics in all cases of necrotic pancreatic infection and suggest that only imipenem or meropenem can be used for no more than three weeks in patients with their pancreatic necrosis area >30% or in patients with biliogenic pancreatitis to decrease the risk of necrotic infection and its mortality rate.