Buprenorphine Affects the Initiation and Severity of Interleukin Induced Acute Pancreatitis in Mice

Acute pancreatitis (AP) is a common disease with no targeted therapy and has varied outcomes ranging from spontaneous resolution to being lethal. While typically painful, AP can also be painless. Various agents, including opioids are used for pain control in AP; the risks, and benefits of which are often debated. Since experimental AP in mice is used to study the efficacy of potential therapies, we studied the effect of a commonly used opioid buprenorphine on the initiation and progression of AP. For this we administered extended-release buprenorphine subcutaneously prior to inducing the previously established severe AP model that uses Interleukins 12 and 18 (IL12,18) in genetically obese (ob/ob) mice and compared this to mice with AP but without the drug. Mice were monitored over 3 days and parameters of AP induction and progression were compared. Buprenorphine significantly reduced the serum amylase, lipase, pancreatic necrosis, and AP associated fat necrosis which is ubiquitous in obese mice and humans. Buprenorphine delayed the AP associated reduction of carotid artery pulse distention, and development of hypothermia, hastened renal injury, and muted the early increase in respiratory rate vs. IL12,18 alone. The site of buprenorphine injection appeared erythematous, inflamed, and microscopically showed thinning, loss of epidermal layers which had increased apoptosis. In summary, subcutaneous extended-release buprenorphine interfered with the induction of AP by reducing serum amylase, lipase, pancreatic and fat necrosis, the worsening of AP by delaying hypotension, hypothermia, while hastening renal injury, respiratory depression, and causing cutaneous injury at the site of injection.

NSAIDs do not reduce severity among post-ERCP pancreatitis patients

OBJECTIVE

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most studied chemoprophylaxis for post-endoscopic retrograde cholangiopancreatography pancreatitis (PEP). While previous systematic reviews have shown NSAIDs reduce PEP, their impact on moderate to severe PEP (MSPEP) is unclear. We conducted a systematic review and meta-analysis to understand the impact of NSAIDs on MSPEP among patients who developed PEP. We later surveyed physicians' understanding of that impact.

DESIGN

A systematic search for randomized trials using NSAIDs for PEP prevention was conducted. Pooled-prevalence and Odds-ratio of PEP, MSPEP were compared between treated vs. control groups. Analysis was performed using R software. Random-effects model was used for all variables. Physicians were surveyed via email before and after reviewing our results.

RESULTS

7688 patients in 25 trials were included. PEP was significantly reduced to 0.598 (95%CI, 0.47-0.76) in the NSAIDs group. Overall burden of MSPEP was reduced among all patients undergoing ERCP: OR 0.59 (95%CI, 0.42-0.83). However, NSAIDs didn't affect the proportion of MSPEP among those who developed PEP (p = 0.658). Rectal Indomethacin and diclofenac reduced PEP but not MSPEP. Efficacy didn't vary by risk, timing of administration, or bias-risk. Survey revealed a change in the impression of the effect of NSAIDs on MSPEP after reviewing our results.

CONCLUSIONS

Rectal diclofenac or indomethacin before or after ERCP reduce the overall burden of MSPEP by reducing the pool of PEP from which it can arise. However, the proportion of MSPEP among patients who developed PEP is unaffected. Therefore, NSAIDs prevent initiation of PEP, but do not affect severity among those that develop PEP. Alternative modalities are needed to reduce MSPEP among patients who develop PEP.

Amphipathic Liponecrosis Impairs Bacterial Clearance and Causes Infection During Sterile Inflammation

BACKGROUND & AIMS

Although transient bacteremia is common during dental and endoscopic procedures, infections developing during sterile diseases like acute pancreatitis (AP) can have grave consequences. We examined how impaired bacterial clearance may cause this transition.

METHODS

Blood samples from patients with AP, normal controls, and rodents with pancreatitis or those administered different nonesterified fatty acids (NEFAs) were analyzed for albumin-unbound NEFAs, microbiome, and inflammatory cell injury. Macrophage uptake of unbound NEFAs using a novel coumarin tracer were done and the downstream effects-NEFA-membrane phospholipid (phosphatidylcholine) interactions-were studied on isothermal titration calorimetry.

RESULTS

Patients with infected AP had higher circulating unsaturated NEFAs; unbound NEFAs, including linoleic acid (LA) and oleic acid (OA); higher bacterial 16S DNA; mitochondrial DNA; altered β-diversity; enrichment in Pseudomonadales; and increased annexin V-positive myeloid (CD14) and CD3-positive T cells on admission. These, and increased circulating dead inflammatory cells, were also noted in rodents with unbound, unsaturated NEFAs. Isothermal titration calorimetry showed progressively stronger unbound LA interactions with aqueous media, phosphatidylcholine, cardiolipin, and albumin. Unbound NEFAs were taken into protein-free membranes, cells, and mitochondria, inducing voltage-dependent anion channel oligomerization, reducing ATP, and impairing phagocytosis. These were reversed by albumin. In vivo, unbound LA and OA increased bacterial loads and impaired phagocytosis, causing infection. LA and OA were more potent for these amphipathic interactions than the hydrophobic palmitic acid.

CONCLUSIONS

Release of stored LA and OA can increase their circulating unbound levels and cause amphipathic liponecrosis of immune cells via uptake by membrane phospholipids. This impairs bacterial clearance and causes infection during sterile inflammation.

Mechanisms linking hypertriglyceridemia to acute pancreatitis

Hypertriglyceridemia (HTG) is a metabolic disorder, defined when serum or plasma triglyceride concentration (seTG) is >1.7 mM. HTG can be categorized as mild to very severe groups based on the seTG value. The risk of acute pancreatitis (AP), a serious disease with high mortality and without specific therapy, increases with the degree of HTG. Furthermore, even mild or moderate HTG aggravates AP initiated by other important etiological factors, including alcohol or bile stone. This review briefly summarizes the pathophysiology of HTG, the epidemiology of HTG-induced AP and the clinically observed effects of HTG on the outcomes of AP. Our main focus is to discuss the pathophysiological mechanisms linking HTG to AP. HTG is accompanied by an increased serum fatty acid (FA) concentration, and experimental results have demonstrated that these FAs have the most prominent role in causing the consequences of HTG during AP. FAs inhibit mitochondrial complexes in pancreatic acinar cells, induce pathological elevation of intracellular Ca²⁺ concentration, cytokine release and tissue injury, and reduce the function of pancreatic ducts. Furthermore, high FA concentrations can induce respiratory, kidney, and cardiovascular failure in AP. All these effects may contribute to the observed increased AP severity and frequent organ failure in patients. Importantly, experimental results suggest that the reduction of FA production by lipase inhibitors can open up new therapeutic options of AP. Overall, investigating the pathophysiology of HTG-induced AP or AP in the presence of HTG and determining possible treatments are needed.