Combination of allopurinol and hyperbaric oxygen therapy: A new treatment in experimental acute necrotizing pancreatitis?

Unveiling the Emerging Role of Xanthine Oxidase in Acute Pancreatitis: Beyond Reactive Oxygen Species

Acute pancreatitis (AP) is a potentially fatal acute digestive disease that is widespread globally. Although significant progress has been made in the previous decade, the study of mechanisms and therapeutic strategies is still far from being completed. Xanthine oxidase (XO) is an enzyme that catalyzes hypoxanthine and xanthine to produce urate and is accompanied by the generation of reactive oxygen species (ROS) in purine catabolism. Considerable preclinical and clinical studies have been conducted over many decades to investigate the role of XO in the pathogenesis of AP and its potential targeting therapeutic value. There is no doubt that the ROS generated by irreversibly activated XO participates in the local pancreas and multiple organ failure during AP. However, the optimal timing and doses for therapeutic interventions targeting XO in animal studies and the clinic, as well as the additional molecular mechanisms through which XO contributes to disease onset and progression, including metabolic regulation, remain to be elucidated. This review summarized the benefits and contradictions of using XO inhibitors in animal models, offered mechanisms other than ROS, and discussed the difficulties faced in clinical trials. We hope to provide a perspective on the future worthwhile basic and clinical research on XO by analyzing its chemical and biological characteristics, as well as the progress of its regulatory mechanisms in AP.

Endoscopic retrograde cholangiopancreatography-induced and non-endoscopic retrograde cholangiopancreatography-induced acute pancreatitis: Two distinct clinical and immunological entities?

Acute pancreatitis (AP) is common gastrointestinal disease of varied aetiology. The most common cause of AP is gallstones, followed by alcohol abuse as an independent risk factor. With the increased need for invasive techniques to treat pancreatic and bile duct pathologies such as endoscopic retrograde cholangiopancreatography (ERCP), AP has emerged as the most frequent complication. While severe AP following ERCP is rare (0.5%), if it does develop it has a greater severity index compared to non-ERCP AP. Development of a mild form of AP after ERCP is not considered a clinically relevant condition. Differences in the clinical presentation and prognosis of the mild and severe forms have been found between non-ERCP AP and post-endoscopic pancreatitis (PEP). It has been proposed that AP and PEP may also have different immunological responses to the initial injury. In this review, we summarise the literature on clinical and inflammatory processes in PEP vs non-ERCP AP.

Enzymatic debridement in necrotizing pancreatitis

Multiple organ failure and pancreatic necrosis are the factors that determine prognosis in acute pancreatitis attacks. We investigated the effects of collagenase on the debridement of experimental pancreatic necrosis. The study covered 4 groups; each group had 10 rats. Group I was the necrotizing pancreatitis group. Group II was the collagenase group with pancreatic loge by isotonic irrigation following necrotizing pancreatitis. Group III was the collagenase group with pancreatic loge following necrotizing pancreatitis. Group IV was the intraperitoneal collagenase group following necrotizing pancreatitis. The progress of the groups was compared hematologically and histopathologically. There was no difference among the groups regarding the levels of leukocyte, hemogram, and urea. The differences in AST levels between Group I and II; and differences in glucose, calcium, LDH, AST, and amylase between Group II and III; between Group II and IV; between Group I and III; and between Group I and IV were statistically significant (P < 0.05). There were statistically significant differences between Group II and III, and Group II and IV regarding edema, acinar necrosis, inflammatory cell infiltration, hemorrhage, and fat necrosis (P < 0.05). In conclusion, the collagenase preparation used in this experimental pancreatitis model was found to be effective in the debridement of pancreatic necrosis.

Sterile inflammatory response in acute pancreatitis

The initial injury in acute pancreatitis is characteristically sterile and results in acinar cells necrosis. Intracellular contents released from damaged cells into the extracellular space serve as damage-associated molecular patterns (DAMPs) that trigger inflammation. There is increasing evidence that this sterile inflammatory response mediated through DAMPs released from necrotic acinar cells is a key determinant of further pancreatic injury, remote organ injury, and disease resolution in experimental models. A number of DAMPS, including high-mobility group box protein 1, DNA, adenosine triphosphate and heat shock protein 70, have been shown to have a role in experimental pancreatitis. Many of these DAMPs are also detectable in the human pancreatitis. Genetic deletion and pharmacologic antagonism demonstrate that specific DAMP receptors, including Toll-like receptor (TLR) 4, TLR9, and P2X7, are also required for inflammation in experimental acute pancreatitis. Downstream DAMP-sensing components include nod-like receptor protein 3, caspase 1, interleukin-1β (IL-1), IL-18, and IL-1 receptor, and also are required for full experimental pancreatitis. These DAMP-mediated pathways provide novel therapeutic targets using antagonists of TLRs and other receptors.

Allopurinol in dermatology

Off-label use is common in dermatology, and is inevitable for rare cutaneous diseases such as perforating dermatosis. Allopurinol is traditionally considered to be a drug for hyperuricemia only, but the recent demonstration of its efficacy in congestive heart failure has spurred renewed interest in its application in other clinical specialties. In dermatology, allopurinol is best known for its severe cutaneous adverse reactions. Recent genomic studies conducted in Taiwan have discovered useful HLA markers for determining the susceptibility of Stevens-Johnson syndrome and toxic epidermal necrolysis associated with allopurinol. Allopurinol has also been used in a number of dermatologic disorders including acquired reactive perforating collagenosis, sarcoidosis, psoriasis and granulomas caused by methacrylate microspheres, silicon and tattoos. Allopurinol may express its therapeutic effects via its antioxidation or anti-inflammatory properties, or its ability to improve vascular function.

Oral allopurinol to prevent hyperamylasemia and acute pancreatitis after endoscopic retrograde cholangiopancreatography

AIM: To assess the efficacy of allopurinol to prevent hyperamylasemia and pancreatitis after endoscopic retrograde cholangiopancreatography (PEP).

METHODS: One hundred and seventy patients were enrolled and randomized to two groups: a study group (n = 85) who received 300 mg of oral allopurinol at 15 h and 3 h before endoscopic retrograde cholangiopancreatography (ERCP) and a control group (n = 85) receiving an oral placebo at the same times. Main Outcome Measurements included serum amylase levels and the number severity of the episodes of pancreatitis. Serum amylase levels were classified as normal (< 150 IU/L) or hyperamylasemia (> 151 IU/L). Episodes of PEP were classified following Ranson’s criteria and CT severity index.

RESULTS: Gender distribution was similar between groups. Mean age was 53.5 ± 18.9 years for study group and 52.8 ± 19.8 years for controls. Also, the distribution of benign pathology was similar between groups. Hyperamylasemia was more common in the control group (P = 0.003). Mild PEP developed in two patients from the study group (2.3%) and eight (9.4%) from control group (P = 0.04), seven episodes were observed in high-risk patients of the control group (25%) and one in the allopurinol group (3.3%, P = 0.02). Risk factors for PEP were precut sphincterotomy (P = 0.02), pancreatic duct manipulation (P = 0.002) and multiple procedures (P = 0.000). There were no deaths or side effects.

CONCLUSION: Oral allopurinol before ERCP decreased the incidences of hyperamylasemia and pancreatitis in patients submitted to high-risk procedures.