Intricacies of host response in acute pancreatitis

Necrotizing pancreatitis: new definitions and a new era in surgical management

BACKGROUND

Necrotizing pancreatitis is a challenging condition that requires surgical treatment commonly and is associated with substantial morbidity and mortality. Over the past decade, new definitions have been developed for standardization of severity of acute and necrotizing pancreatitis, and new management techniques have emerged based on prospective, randomized clinical trials.

METHODS

Review of English-language literature.

RESULTS

A new international classification of acute pancreatitis has been developed by PANCREA (Pancreatitis Across Nations Clinical Research and Education Alliance) to replace the Atlanta Classification. It is based on the actual local (whether pancreatic necrosis is present or not, whether it is sterile or infected) and systemic determinants (whether organ failure is present or not, whether it is transient or persistent) of severity. Early management requires goal-directed fluid resuscitation (with avoidance of over-resuscitation and abdominal compartment syndrome), assessment of severity of pancreatitis, diagnostic computed tomography (CT) imaging to assess for necrotizing pancreatitis, consideration of endoscopic retrograde cholangiopancreatography (ERCP) for biliary pancreatitis and early enteral nutrition support. Antibiotic prophylaxis is not recommended. Therapeutic antibiotics are required for treatment of documented infected pancreatic necrosis. The initial treatment of infected pancreatic necrosis is percutaneous catheter or endoscopic (transgastric/transduodenal) drainage with a second drain placement as required. Lack of clinical improvement after these initial procedures warrants consideration of minimally invasive techniques for pancreatic necrosectomy including video-assisted retroperitoneal debridement (VARD), minimally invasive retroperitoneal pancreatectomy (MIRP), or transluminal direct endoscopic necrosectomy (DEN). Open necrosectomy is associated with substantial morbidity, but to date no randomized trial has documented superiority of either minimally invasive or open surgical technique. Additional trials are underway to address this.

CONCLUSIONS

Severe acute and necrotizing pancreatitis requires a multi-disciplinary treatment strategy that must be individualized for each patient. Optimal treatment of necrotizing pancreatitis now requires a staged, multi-disciplinary, minimally invasive "step-up" approach that includes a team of interventional radiologists, therapeutic endoscopists, and surgeons.

Inhibition of hydrogen sulfide synthesis provides protection for severe acute pancreatitis rats via apoptosis pathway

We aimed to investigate the relationship between the synthesis of hydrogen sulfide (H(2)S) and the pancreatic acinar cell apoptosis in severe acute pancreatitis (SAP) rats, as well as analyse the potential apoptotic pathway involved in this process. Sixty rats had been equally divided into four groups: sham, SAP, SAP + sodium hydrosulfide (NaHS) and SAP + DL-propargylglycine (PAG). 24 h after SAP induction, all surviving animals of each group were sacrificed to collect blood and tissue samples for the following measurements: the level of serum H(2)S as well as the levels of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), H(2)S synthesizing activity, CSE mRNA and protein expression, maleic dialdehyde (MDA) and myeloperoxidase (MPO) activity, the expression of Bax, Bcl-2, caspase-3, -8 and -9, the release of cytochrome c and the activation of nuclear factor-kappa B (NF-κB), ERK1/2, JNK1/2 and p38 in pancreas. Furthermore, in situ detection of cell apoptosis was examined and the severity of pancreatic damage was analyzed by pathological grading and scoring. Results Significant differences in every index except IL-10 had been found between the SAP, NaHS and PAG groups (P < 0.05). Treatment with PAG obviously induced the pancreatic acinar cell apoptosis as well as improved all the pathological changes and inflammatory parameters. In contrast, administration of NaHS significantly attenuated apoptosis in the pancreas and aggravated the severity of pancreatic damage. Moreover, the expressions of caspase-3, -8, -9 and the release of cytochrome c were all increased in the apoptotic cells, and the activity of NF-κB as well as the phosphorylation of ERK1/2, JNK1/2 and p38 decreased accompanying with the reduction of the serum H(2)S level. H(2)S plays a pivotal role in the regulation of pancreatic acinar cell apoptosis in SAP rats. The present results showed that inhibition of H(2)S synthesis provided protection for SAP rats via inducing acinar cell apoptosis. This process acted through both extrinsic and intrinsic apoptotic pathways, and may be regulated by reducing the activity of NF-κB.

The role of antimicrobial therapy in severe acute pancreatitis

The role of antimicrobial therapy in patients with severe acute pancreatitis is to treat secondary pancreatic infections to prevent systemic sepsis and death. Infected pancreatic necrosis is diagnosed using image-directed fine needle aspiration with culture and Gram's stain. Prophylactic antibiotics have not proven efficacious, while the precise timely detection of secondary pancreatic infections is often elusive. A high clinical index of suspicion should prompt the empiric initiation of antimicrobial therapy until culture results are available. Positive cultures should guide antimicrobial therapy, and for infected pancreatic necrosis, antibiotics should be used in conjunction with interventional techniques for source control.

Down-regulation of tumor necrosis factor-associated factor 6 is associated with progression of acute pancreatitis complicating lung injury in mice

Acute lung injury is one of the critical complications of acute pancreatitis (AP). Tumor necrosis factor-associated factor 6 (TRAF6) is a key adaptor that regulates various inflammatory signaling pathways, including those mediated by Toll-like receptors (TLRs). This study was performed to investigate the potential role of TRAF6 in the pathogenesis of AP and pancreatitis-associated acute lung injury using a mouse model of caerulein-induced AP (CAP). CAP was induced by intraperitoneal injection of caerulein hourly for 7 times (50 microg/kg), and control mice were treated with saline of the same volume. Typical pancreatic and lung inflammation was observed in the early stage (1 h) of CAP, as judged by morphological changes. Likewise, in CAP mice, the pancreatic myeloperoxidase activity and serum levels of interleukin-6 and interleukin-10 were significantly increased after 2 h, peaked at 4h, and then decreased by 24 h. The expression of TRAF6 was then studied by real time-PCR, immunohistochemistry, and Western blot analysis. Compared with control group, TRAF6 mRNA level was decreased in CAP group within the first 12 h, and then significantly increased after 24 h, which was in accordance with the protein level detected by Western blot analysis and immunohistochemistry. Moreover, TRAF6 protein was expressed in both pancreatic acinar cells and lung bronchial epithelial cells. In conclusion, the down-regulation of TRAF6 was associated with increased inflammatory severity in the pancreas and lung, suggesting that TRAF6 is involved in the anti-inflammatory process during AP. TRAF6 may be a potential molecular target for treating AP.

Severe acute pancreatitis: Clinical course and management

Severe acute pancreatitis (SAP) develops in about 25% of patients with acute pancreatitis (AP). Severity of AP is linked to the presence of systemic organ dysfunctions and/or necrotizing pancreatitis pathomorphologically. Risk factors determining independently the outcome of SAP are early multi-organ failure, infection of necrosis and extended necrosis (>50%). Up to one third of patients with necrotizing pancreatitis develop in the late course infection of necroses. Morbidity of SAP is biphasic, in the first week strongly related to early and persistence of organ or multi-organ dysfunction. Clinical sepsis caused by infected necrosis leading to multi-organ failure syndrome (MOFS) occurs in the later course after the first week. To predict sepsis, MOFS or deaths in the first 48-72 h, the highest predictive accuracy has been objectified for procalcitonin and IL-8; the Sepsis-Related Organ Failure Assessment (SOFA)-score predicts the outcome in the first 48 h, and provides a daily assessment of treatment response with a high positive predictive value. Contrast-enhanced CT provides the highest diagnostic accuracy for necrotizing pancreatitis when performed after the first week of disease. Patients who suffer early organ dysfunctions or at risk of developing a severe disease require early intensive care treatment. Early vigorous intravenous fluid replacement is of foremost importance. The goal is to decrease the hematocrit or restore normal cardiocirculatory functions. Antibiotic prophylaxis has not been shown as an effective preventive treatment. Early enteral feeding is based on a high level of evidence, resulting in a reduction of local and systemic infection. Patients suffering infected necrosis causing clinical sepsis, pancreatic abscess or surgical acute abdomen are candidates for early intervention. Hospital mortality of SAP after interventional or surgical debridement has decreased in high volume centers to below 20%.

Severe acute pancreatitis: Clinical course and management

Severe acute pancreatitis (SAP) develops in about 25% of patients with acute pancreatitis (AP). Severity of AP is linked to the presence of systemic organ dysfunctions and/or necrotizing pancreatitis pathomorphologically. Risk factors determining independently the outcome of SAP are early multi-organ failure, infection of necrosis and extended necrosis (> 50%). Up to one third of patients with necrotizing pancreatitis develop in the late course infection of necroses. Morbidity of SAP is biphasic, in the first week strongly related to early and persistence of organ or multi-organ dysfunction. Clinical sepsis caused by infected necrosis leading to multi-organ failure syndrome (MOFS) occurs in the later course after the first week. To predict sepsis, MOFS or deaths in the first 48-72 h, the highest predictive accuracy has been objectified for procalcitonin and IL-8; the Sepsis-Related Organ Failure Assessment (SOFA)-score predicts the outcome in the first 48 h, and provides a daily assessment of treatment response with a high positive predictive value. Contrast-enhanced CT provides the highest diagnostic accuracy for necrotizing pancreatitis when performed after the first week of disease. Patients who suffer early organ dysfunctions or at risk of developing a severe disease require early intensive care treatment. Early vigorous intravenous fluid replacement is of foremost importance. The goal is to decrease the hematocrit or restore normal cardiocirculatory functions. Antibiotic prophylaxis has not been shown as an effective preventive treatment. Early enteral feeding is based on a high level of evidence, resulting in a reduction of local and systemic infection. Patients suffering infected necrosis causing clinical sepsis, pancreatic abscess or surgical acute abdomen are candidates for early intervention. Hospital mortality of SAP after interventional or surgical debridement has decreased in high volume centers to below 20%.

Role of tumor necrosis factor-alpha in acute pancreatitis: from biological basis to clinical evidence

Tumor necrosis factor (TNF)-alpha is a pleiotropic cytokine that exerts host-damaging effects in different autoimmune and inflammatory diseases. It is a key regulator of other proinflammatory cytokines and of leukocyte adhesion molecules, and it is a priming activator of immune cells. In recent years, several research lines-mostly derived from animal models and in vitro studies-suggested that TNF-alpha plays a pivotal role in the pathogenesis of acute pancreatitis. In particular, it contributes to the systemic progression of the inflammatory response and to the end-organ dysfunction often observed in severe disease. Current clinical applications of TNF-alpha in acute pancreatitis include the assessment of blood concentrations to predict disease severity and to identify individuals prone to develop complications such as multiple organ failure and septic shock. However, TNF-alpha is rapidly cleared from the bloodstream, and sensitivity and overall accuracy of its measurement seem strictly time dependent, thereby being of potential prognostic value only in the first days after the onset of the disease. In parallel, TNF-alpha has been evaluated as a novel pharmacologic target for treating pancreatitis. Although promising results have been observed in the laboratory, transition to clinical practice seems problematic, in particular, in the light of divergent results obtained in sepsis trials. Therefore, in future clinical trials pertaining to TNF-alpha neutralization in acute pancreatitis, timing of intervention should be related to changes in TNF-alpha serum levels, and inclusion and exclusion criteria should be accurately selected to better define the population most likely to benefit.

New advances in pancreatic surgery

PURPOSE OF REVIEW

New understanding of the dynamic of acute pancreatitis, the clinical impact of local pathology in chronic pancreatitis and cystic neoplastic lesions bearing high potential for malignant transformation has changed the management of pancreatic diseases.

RECENT FINDINGS

In acute pancreatitis, risk factors independently determining outcome in severe acute pancreatitis are early and persistent multiorgan failure, infected necrosis and extended sterile necrosis. The management of severe acute pancreatitis is based on early intensive-care treatment and late surgical debridement. In chronic pancreatitis, recent data from randomized controlled clinical trials have demonstrated duodenum-preserving pancreatic head resection with an inflammatory mass of the head as superior to pylorus-preserving Whipple resection. Cystic neoplasms are local lesions of the pancreas with high malignant potential. Local organ-preserving resection techniques have been applied with low morbidity and mortality, replacing a Whipple-type resection. Resection of pancreatic cancer is ineffective to cure patients. After an R0-resection, a significant survival benefit has been achieved when adjuvant chemotherapy has additionally been applied.

SUMMARY

New knowledge about the nature of inflammatory diseases, cystic neoplastic lesions and malignant pancreatic tumours has changed the indication for surgical treatment and the application of organ-preserving surgical techniques.