Morphine worsens the severity and prevents pancreatic regeneration in mouse models of acute pancreatitis

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. Although 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. As 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 before 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 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 the development of hypothermia, hastened renal injury, and muted the early increase in respiratory rate versus IL12,18 alone. The site of buprenorphine injection appeared erythematous, inflamed, and microscopically showed thinning, loss of epidermal layers that 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.NEW & NOTEWORTHY Extended-release buprenorphine interferes with the initiation and progression of acute pancreatitis at multiple levels.

Prescription opioids induced microbial dysbiosis worsens severity of chronic pancreatitis and drives pain hypersensitivity

Opioids, such as morphine and oxycodone, are widely used for pain management associated with chronic pancreatitis (CP); however, their impact on the progression and pain sensitivity of CP has never been evaluated. This report investigates the impact of opioid use on the severity of CP, pain sensitivity, and the gut microbiome. C57BL/6 mice were divided into control, CP, CP with morphine/oxycodone, and either morphine or oxycodone alone groups. CP was induced by administration of caerulein (50ug/kg/h, i.p. hourly x7, twice a week for 10 weeks). The mouse-to-pancreas weight ratio, histology, and Sirius red staining were performed to measure CP severity. Tail flick and paw pressure assays were used to measure thermal and mechanical pain. DNA was extracted from the fecal samples and subjected to whole-genome shotgun sequencing. Germ-free mice were used to validate the role of gut microbiome in sensitizing acute pancreatic inflammation. Opioid treatment exacerbates CP by increasing pancreatic necrosis, fibrosis, and immune-cell infiltration. Opioid-treated CP mice exhibited enhanced pain hypersensitivity and showed distinct clustering of the gut microbiome compared to untreated CP mice, with severely compromised gut barrier integrity. Fecal microbiota transplantation (FMT) from opioid-treated CP mice into germ-free mice resulted in pancreatic inflammation in response to a suboptimal caerulein dose. Together, these analyses revealed that opioids worsen the severity of CP and induce significant alterations in pain sensitivity and the gut microbiome in a caerulein CP mouse model. Microbial dysbiosis plays an important role in sensitizing the host to pancreatic inflammation.

Molecular mechanisms of pain in acute pancreatitis: recent basic research advances and therapeutic implications

Although severe abdominal pain is the main symptom of acute pancreatitis, its mechanisms are poorly understood. An emerging body of literature evidence indicates that neurogenic inflammation might play a major role in modulating the perception of pain from the pancreas. Neurogenic inflammation is the result of a crosstalk between injured pancreatic tissue and activated neurons, which leads to an auto-amplification loop between inflammation and pain during the progression of acute pancreatitis. In this review, we summarize recent findings on the role of neuropeptides, ion channels, and the endocannabinoid system in acute pancreatitis-related pain. We also highlight potential therapeutic strategies that could be applied for managing severe pain in this disease.

Safety and efficacy of intravenous hydromorphone patient-controlled analgesia versus intramuscular pethidine in acute pancreatitis: An open-label, randomized controlled trial

Background: Hydromorphone patient-controlled analgesia (PCA) provides satisfactory postoperative pain therapy, but its effect has not been assessed in acute pancreatitis (AP).

Aim: To assess the safety and efficacy of intravenous hydromorphone PCA for pain relief in AP.

Methods: This open-label trial included AP patients admitted within 72 h of symptom onset, aged 18–70 years old, and with Visual Analog Scale (VAS) for pain intensity ≥5. They were randomized to receive intravenous hydromorphone PCA (0.05 mg/h with 0.2 mg on-demand) or intramuscular pethidine (50 mg as required) for three consecutive days. Intramuscular dezocine (5 mg on demand) was the rescue analgesia. The primary outcome was the change of VAS score recorded every 4 h for 3 days. Interim analysis was conducted by an Independent Data and Safety Monitoring Committee (IDSMC).

Results: From 26 July 2019 to 15 January 2020, 77 patients were eligible for the intention-to-treat analysis in the interim analysis (39 in the hydromorphone group and 38 in the pethidine group). Baseline parameters were comparable between groups. No difference in VAS between the two groups was found. Hydromorphone PCA was associated with higher moderately severe to severe cases (82.1% vs. 55.3%, p = 0.011), acute peripancreatic fluid collections (53.9% vs. 28.9%, p = 0.027), more cumulative opioid consumption (median 46.7 vs. 5 mg, p < 0.001), higher analgesia costs (median 85.5 vs. 0.5 $, p < 0.001) and hospitalization costs (median 3,778 vs. 2,273 $, p = 0.007), and more adverse events (20.5% vs. 2.6%, p = 0.087). The per-protocol analysis did not change the results. Although a sample size of 122 patients was planned, the IDSMC halted further recruitment as disease worsening or worse clinical outcomes between the groups in the interim analysis.

Conclusion: Hydromorphone PCA was not superior to pethidine in relieving pain in AP patients and might have worse clinical outcomes. Therefore, its use is not recommended.

Clinical Trial Registration: Chictr.org.cn. ChiCTR1900025971

Pancreas and Adverse Drug Reactions: A Literature Review

Adverse drug reactions (ADRs) affecting the pancreas are a heterogeneous group of side effects that cause damage to pancreatic cells. Various mechanisms such as hypersensitization, sphincter of Oddi constriction, direct cytotoxic and metabolic effects on pancreatic cells, and dose-dependent idiosyncrasy lead to intrapancreatic activation of pancreatic enzymes resulting in drug-induced acute pancreatitis. Several medications have been linked with the development of pancreatic cancer. Pancreatic cancer may result from proinflammatory, proliferative, and antiapoptotic effects. Diabetogenic effect of drugs, which is understood as impairment of insulin secretion, may occur due to direct destruction of β cells, systemic toxicity affecting pancreatic islets and cell membrane glucose transporters, induction of Th1-type autoimmune response, and impairment of voltage-gated calcium channels in β cells, endoplasmic reticulum stress, and insulin signaling. A better understanding of ADRs that affect the pancreas may contribute to improving the awareness of clinicians and patients and reducing potential harmful side effects of implemented therapies.

Drug D, a Diosgenin Derive, Inhibits L-Arginine-Induced Acute Pancreatitis through Meditating GSDMD in the Endoplasmic Reticulum via the TXNIP/HIF-1α Pathway

Acute pancreatitis (AP) is one of the most common causes of hospitalization for gastrointestinal diseases, with high morbidity and mortality. Endoplasmic reticulum stress (ERS) and Gasdermin D (GSDMD) mediate AP, but little is known about their mutual influence on AP. Diosgenin has excellent anti-inflammatory and antioxidant effects. This study investigated whether Diosgenin derivative D (Drug D) inhibits L-arginine-induced acute pancreatitis through meditating GSDMD in the endoplasmic reticulum (ER). Our studies were conducted in a mouse model of L-arginine-induced AP as well as in an in vitro model on mouse pancreatic acinar cells. The GSDMD accumulation in ER was found in this study, which caused ERS of acinar cells. GSDMD inhibitor Disulfiram (DSF) notably decreased the expression of GSDMD in ER and TXNIP/HIF-1α signaling. The molecular docking study indicated that there was a potential interaction between Drug D and GSDMD. Our results showed that Drug D significantly inhibited necrosis of acinar cells dose-dependently, and we also found that Drug D alleviated pancreatic necrosis and systemic inflammation by inhibiting the GSDMD accumulation in the ER of acinar cells via the TXNIP/HIF-1α pathway. Furthermore, the level of p-IRE1α (a marker of ERS) was also down-regulated by Drug D in a dose-dependent manner in AP. We also found that Drug D alleviated TXNIP up-regulation and oxidative stress in AP. Moreover, our results revealed that GSDMD^-/- mitigated AP by inhibiting TXNIP/HIF-1α. Therefore, Drug D, which is extracted from Dioscorea zingiberensis, may inhibit L-arginine-induced AP by meditating GSDMD in the ER by the TXNIP /HIF-1α pathway.

Murine Chronic Pancreatitis Model Induced by Partial Ligation of the Pancreatic Duct Encapsulates the Profile of Macrophage in Human Chronic Pancreatitis

Immune responses are an integral part of the pathogenesis of pancreatitis. Studies applying the mouse model of pancreatitis induced by partial ligation of the pancreatic duct to explore the pancreatic immune microenvironment are still lacking. The aim of the present study is to explore the macrophage profile and associated regulatory mechanisms in mouse pancreatitis, as well as the correlation with human chronic pancreatitis (CP). In the present study, the mouse model of pancreatitis was induced by partial ligation of the pancreatic duct. Mice in the acute phase were sacrificed at 0, 4, 8, 16, 32, 72 h after ligation, while mice in the chronic phase were sacrificed at 7, 14, 21, 28 days after ligation. We found that the pancreatic pathological score, expression of TNF-α and IL-6 were elevated over time and peaked at 72h in the acute phase, while in the chronic phase, the degree of pancreatic fibrosis peaked at day 21 after ligation. Pancreatic M1 macrophages and pyroptotic macrophages showed a decreasing trend over time, whereas M2 macrophages gradually rose and peaked at day 21. IL-4 is involved in the development of CP and is mainly derived from pancreatic stellate cells (PSCs). The murine pancreatitis model constructed by partial ligation of the pancreatic duct, especially the CP model, can ideally simulate human CP caused by obstructive etiologies in terms of morphological alterations and immune microenvironment characteristics.

Analgesia in the Initial Management of Acute Pancreatitis: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

BACKGROUND

The optimal analgesic strategy for patients with acute pancreatitis (AP) remains unknown.

OBJECTIVE

The present systematic review and meta-analysis aims to compare the efficacy of different analgesic modalities trialled in AP.

METHODS

A systematic search of PubMed, MEDLINE, EMBASE, CENTRAL, SCOPUS and Web of Science conducted up until June 2021, identified all randomised control trials (RCTs) comparing analgesic modalities in AP. A pooled analysis was undertaken of the improvement in pain scores as reported on visual analogue scale (VAS) on day 0, day 1 and day 2.

RESULTS

Twelve RCTs were identified including 542 patients. Seven trial drugs were compared: opiates, non-steroidal anti-inflammatories (NSAIDs), metamizole, local anaesthetic, epidural, paracetamol, and placebo. Across all modalities, the pooled VAS scores showed global improvement from baseline to day 2. Epidural analgesia appears to provide the greatest improvement in VAS within the first 24 h but is equivalent to opiates by 48 h. Within 24 h, NSAIDs offered similar pain-relief to opiates, while placebo also showed equivalence to other modalities but then plateaued. Local anaesthetics demonstrated least overall efficacy. VAS scores for opiate and non-opiate analgesics were comparable at baseline and day 1. The identified RCTs demonstrated significant statistical and methodological heterogeneity in pain-relief reporting.

CONCLUSIONS

There is remarkable paucity of level 1 evidence to guide pain management in AP with small datasets per study. Epidural administration appears effective within the first 24 h of AP although infrequently used and featured in only a single RCT. NSAIDs are an effective opiate sparing alternative during the first 24 h.

Novel role of the Mu-opioid receptor in pancreatic cancer: potential link between opioid use and cancer progression

Opioids are the most popular drugs for both acute and chronic pain management. The G protein-coupled mu-opioid receptor (MOR) is the therapeutic target for most clinically used opioids, including morphine. A mounting number of publications suggest a relationship between the MOR and possible cancer progression and recurrence extending to managing chronic cancer pain. In this study, we studied the possible link between opioid use and pancreatic cancer (PC) progression. We found increased MOR expression in murine and human PC cell lines, human PC-derived organoids, and in the undifferentiated or poorly differentiated areas of surgically resected PC tissues. Direct stimulation of MOR by morphine (MOR agonist) caused a significant dose-dependent increase in proliferation, invasion, and levels of stemness markers in PC cells. In a co-culture system, MOR stimulation of macrophages also resulted in increased proliferation of PC cells. MOR overexpression increased proliferation and cancer stemness, whereas knock-down of MOR followed opposite results in the PC cells. Morphine induced chemoresistance to conventional chemotherapeutic agents used for PC treatment. Overall, our results suggest that MOR is expressed in pancreatic cancer and may be involved in tumor progression and chemoresistance.

Fentanyl but Not Morphine or Buprenorphine Improves the Severity of Necrotizing Acute Pancreatitis in Rats

Opioids are widely used for the pain management of acute pancreatitis (AP), but their impact on disease progression is unclear. Therefore, our aim was to study the effects of clinically relevant opioids on the severity of experimental AP. Various doses of fentanyl, morphine, or buprenorphine were administered as pre- and/or post-treatments in rats. Necrotizing AP was induced by the intraperitoneal injection of L-ornithine-HCl or intra-ductal injection of Na-taurocholate, while intraperitoneal caerulein administration caused edematous AP. Disease severity was determined by laboratory and histological measurements. Mu opioid receptor (MOR) expression and function was assessed in control and AP animals. MOR was expressed in both the pancreas and brain. The pancreatic expression and function of MOR were reduced in AP. Fentanyl post-treatment reduced necrotizing AP severity, whereas pre-treatment exacerbated it. Fentanyl did not affect the outcome of edematous AP. Morphine decreased vacuolization in edematous AP, while buprenorphine pre-treatment increased pancreatic edema during AP. The overall effects of morphine on disease severity were negligible. In conclusion, the type, dosing, administration route, and timing of opioid treatment can influence the effects of opioids on AP severity. Fentanyl post-treatment proved to be beneficial in AP. Clinical studies are needed to determine which opioids are best in AP.

Effects of the peripherally acting μ-opioid receptor antagonist methylnaltrexone on acute pancreatitis severity: study protocol for a multicentre double-blind randomised placebo-controlled interventional trial, the PAMORA-AP trial

Background

Moderate to severe acute pancreatitis (AP) is associated with a high rate of complications and increased mortality, yet no targeted pharmacologic treatment currently exists. As pain is a dominant symptom in AP, patients are exposed to excess levels of both endo- and exogenous opioids, which may have harmful effects on the course of AP. This trial investigates the effects of the peripherally acting μ-opioid receptor antagonist (PAMORA) methylnaltrexone on disease severity and clinical outcomes in patients with moderate to severe AP.

Methods

PAMORA-AP is a multicentre, investigator-initiated, double-blind, randomised, placebo-controlled, interventional trial, which will be conducted at four referral centres for acute pancreatitis in Denmark. Ninety patients with early-onset AP (pain onset within 48 h) as well as predicted moderate to severe disease (two or more systemic inflammatory response syndrome criteria upon admission) will be prospectively included. Subsequently, participants will be randomised (1:1) to intravenous treatment with either methylnaltrexone or matching placebo (Ringer’s lactate) during 5 days of admission. The primary endpoint will be the group difference in disease severity as defined and measured by the Pancreatitis Activity Scoring System (PASS) score 48 h after randomisation. Secondary endpoints include daily PASS scores; disease severity according to the Atlanta classification; quantification of need for analgesics, nutritional support, intravenous fluid resuscitation and antibiotics; duration of hospital admissions, readmission rates and mortality. Pain intensity and gut function will be self-reported using validated questionnaires. Exploratory endpoints include circulating levels of pro-and anti-inflammatory markers, polyethylene glycol recovery from the urine, circulating levels of blood markers of intestinal permeability, the prevalence of pancreatic complications on computed tomography (CT) scans, and colon transit time assessed using a CT-based radiopaque marker method.

Discussion

This trial aims to evaluate the PAMORA methylnaltrexone as a novel targeted pharmacotherapy in patients with moderate to severe AP with the potential benefit of improved patient outcomes.

Trial registration

ClinicalTrials.govNCT04743570. Registered on 28 January 2021. EudraCT 2020-002313-18.

Analysis of Pain and Analgesia Protocols in Acute Cerulein-Induced Pancreatitis in Male C57BL/6 Mice

Pancreatitis is known to be painful in humans and companion animals. However, the extent of pain in experimental mouse models of acute pancreatitis is unknown. Consequently, the severity classification of acute pancreatitis in mice is controversially discussed and standardized pain management is missing. In this study, we investigated acute Cerulein-induced pancreatitis with pain-specific and well-being orientated parameters to detect its impact on mice. Male C57BL/6J male mice were injected with Cerulein; animals that received saline injections served as control group. The animals were observed for weight change and water intake. To assess pain, behaviors like stretch-and-press and reduced rearing, the Mouse Grimace Scale, and von Frey hypersensitivity were assessed. Fecal corticosterone metabolites and burrowing behavior were assessed to detect changes in the animal’s well-being. Pancreatitis severity was evaluated with amylase and lipase in the blood and pancreas histology. To investigate whether different analgesics can alleviate signs of pain, and if they influence pancreas inflammation, animals received Buprenorphine, Paracetamol in combination with Tramadol, or Metamizole in the drinking water. The calculated intake of these analgesics via drinking reached values stated to be efficient for pain alleviation. While pancreatitis did not seem to be painful, we detected acute pain from Cerulein injections that could not be alleviated by analgesics. The number of inflammatory cells in the pancreas did not differ with the analgesic administered. In conclusion: (1) Cerulein injections appear to be acutely painful but pain could not be alleviated by the tested analgesics, (2) acute pancreatitis induced by our protocol did not induce obvious signs of pain, (3) analgesic substances had no detectable influence on inflammation. Nevertheless, protocols inducing more severe or even chronic pancreatitis might evoke more pain and analgesic treatment might become imperative. Considering our results, we recommend the use of Buprenorphine via drinking water in these protocols. Further studies to search for efficient analgesics that can alleviate the acute pain induced by Cerulein injections are needed.

Pain sensing neurons promote tissue regeneration in adult mice

Tissue repair after injury in adult mammals, usually results in scarring and loss of function in contrast to lower vertebrates such as the newt and zebrafish that regenerate. Understanding the regulatory processes that guide the outcome of tissue repair is therefore a concerning challenge for regenerative medicine. In multiple regenerative animal species, the nerve dependence of regeneration is well established, but the nature of the innervation required for tissue regeneration remains largely undefined. Using our model of induced adipose tissue regeneration in adult mice, we demonstrate here that nociceptive nerves promote regeneration and their removal impairs tissue regeneration. We also show that blocking the receptor for the nociceptive neuropeptide calcitonin gene-related peptide (CGRP) inhibits regeneration, whereas CGRP administration induces regeneration. These findings reveal that peptidergic nociceptive neurons are required for adult mice tissue regeneration.

Tissue Regeneration: The Dark Side of Opioids

Opioids are regarded as among the most effective analgesic drugs and their use for the management of pain is considered standard of care. Despite their systematic administration in the peri-operative period, their impact on tissue repair has been studied mainly in the context of scar healing and is only beginning to be documented in the context of true tissue regeneration. Indeed, in mammals, growing evidence shows that opioids direct tissue repair towards scar healing, with a loss of tissue function, instead of the regenerative process that allows for recovery of both the morphology and function of tissue. Here, we review recent studies that highlight how opioids may prevent a regenerative process by silencing nociceptive nerve activity and a powerful anti-inflammatory effect. These data open up new perspectives for inducing tissue regeneration and argue for opioid-restricted strategies for managing pain associated with tissue injury.

Heroin-Induced Acute Pancreatitis

Heroin-induced pancreatitis (HIP) is rare with only a few cases reported previously in the literature and the pathophysiology mechanism is yet to be investigated. We present two cases of acute pancreatitis (AP) in the setting of acute heroin (diacetylmorphine) intoxication. Both patients presented with nausea, vomiting and severe abdominal pain after intranasal heroin use. On laboratory analysis were found to have elevated serum lipase, positive urine toxicology for opioids, without any other obvious causes for AP. Both patients had a full recovery with supportive treatment. As a general approach, drug-induced pancreatitis is a diagnosis of exclusion and a high index of suspicion is required when the most common etiologies are ruled out.

Ketamine and xylazine effects in murine model of acute pancreatitis

Ketamine and xylazine (Ket/Xyl) are anesthetic agents that target neural pathways and are commonly used in combination in mouse studies. Since neural pathways can modulate acute pancreatitis severity, we asked if Ket/Xyl affect disease severity. C57BL/6 mice were treated with six hourly injections of cerulein to induce mild acute pancreatitis. Mice were also treated with and without ketamine, xylazine, and Ket/Xyl before pancreatitis induction in vivo and in vitro. Ket/Xyl pretreatment in vivo increased selected parameters of pancreatitis severity such as trypsin activity and edema; these effects were predominantly mediated by xylazine. Ket/Xyl also changed markers of autophagy. These in vivo effects of Ket/Xyl were not attenuated by atropine. The drugs had no little to no effect on pancreatitis responses in isolated pancreatic cells or lobules. These findings suggest that Ket/Xyl administration can have substantial effect on acute pancreatitis outcomes through nonmuscarinic neural pathways. Given widespread use of this anesthetic combination in experimental animal models, future studies of inflammation and injury using Ket/Xyl should be interpreted with caution.NEW & NOTEWORTHY Ketamine and xylazine anesthetic agent administration before acute pancreatitis induction in mice lead to changes in pancreatitis responses independent of acute pancreatitis induction. Future studies should consider the potential effects of anesthesia administration when studying disease processes associated with inflammation and injury.

The Altered Migration and Distribution of Systemically Administered Mesenchymal Stem Cells in Morphine-Treated Recipients

Mesenchymal stem cells (MSCs) have the ability to migrate to the site of injury or inflammation, and to contribute to the healing process. Since patients treated with MSCs are often users of analgesic drugs, to relieve their uncomfortable pain associated with the tissue disorder, there is a possibility of negative effects of these drugs on the migration of endogenous and exogenous MSCs. Therefore, we tested the impact of acute and chronic treatment with morphine on the migration and organ distribution of exogenous adipose tissue-derived MSCs in mouse models. Firstly, we showed that the incubation of MSCs with morphine significantly reduced the expression of adhesive molecules CD44 (HCAM), CD54 (ICAM-1) and CD106 (VCAM-1) on MSCs. Using a model of systemic administration of MSCs labeled with vital dye PKH26 and by the application of flow cytometry to detect living CD45^-PKH26⁺ cells, we found a decreased number of labeled MSCs in the lung, spleen and bone marrow, and a significantly increased number of MSCs in the liver of morphine-treated recipients. A skin allograft model was used to study the effects of morphine on the migration of exogenous MSCs to the superficial wound. Intraperitoneally administered MSCs migrated preferentially to the wound site, and this migration was significantly decreased in the morphine-treated recipients. The present results showed that morphine significantly influences the distribution of exogenous MSCs in the body, and decreases their migration to the site of injury.

Characteristic pancreatic and splenic immune cell infiltration patterns in mouse acute pancreatitis

BACKGROUND

A systemic evaluation of immune cell infiltration patterns in experimental acute pancreatitis (AP) is lacking. Using multi-dimensional flow cytometry, this study profiled infiltrating immune cell types in multiple AP mouse models.

METHODS

Three AP models were generated in C57BL/6 mice via cerulein (CAE) injection, alcohol and palmitoleic acid (EtOH + POA) injection, and alcohol diet feeding and cerulein (EtOH + CAE) injection. Primary pancreatic cells and splenocytes were prepared, and multi-dimensional flow cytometry was performed and analyzed by manual gating and computerized PhenoGraph, followed by visualization with t-distributed stochastic neighbor embedding (t-SNE).

RESULTS

CAE treatment induced a time-dependent increase of major innate immune cells and a decrease of follicular B cells, and TCD4+ cells and the subtypes in the pancreas, whereas elicited a reversed pattern in the spleen. EtOH + POA treatment resulted in weaker effects than CAE treatment. EtOH feeding enhanced CAE-induced amylase secretion, but unexpectedly attenuated CAE-induced immune cell regulation. In comparison with manual gating analysis, computerized analysis demonstrated a remarkable time efficiency and reproducibility on the innate immune cells and B cells.

CONCLUSIONS

The reverse pattern of increased innate and decreased adaptive immune cells was consistent in the pancreas in CAE and EtOH + POA treatments. Alcohol feeding opposed the CAE effect on immune cell regulation. Together, the immune profiling approach utilized in this study provides a better understanding of overall immune responses in AP, which may facilitate the identification of intervention windows and new therapeutic strategies. Computerized analysis is superior to manual gating by dramatically reducing analysis time.

A narrative review of acute pancreatitis and its diagnosis, pathogenetic mechanism, and management

Acute pancreatitis (AP) is an inflammatory disease that can progress to severe acute pancreatitis (SAP), which increases the risk of death. AP is characterized by inappropriate activation of trypsinogen, infiltration of inflammatory cells, and destruction of secretory cells. Other contributing factors may include calcium (Ca²⁺) overload, mitochondrial dysfunction, impaired autophagy, and endoplasmic reticulum (ER) stress. In addition, exosomes are also associated with pathophysiological processes of many human diseases and may play a biological role in AP. However, the pathogenic mechanism has not been fully elucidated and needs to be further explored to inform treatment. Recently, the treatment guidelines have changed; minimally invasive therapy is advocated more as the core multidisciplinary participation and "step-up" approach. The surgical procedures have gradually changed from open surgery to minimally invasive surgery that primarily includes percutaneous catheter drainage (PCD), endoscopy, small incision surgery, and video-assisted surgery. The current guidelines for the management of AP have been updated and revised in many aspects. The type of fluid to be used, the timing, volume, and speed of administration for fluid resuscitation has been controversial. In addition, the timing and role of nutritional support and prophylactic antibiotic therapy, as well as the timing of the surgical or endoscopic intervention, and the management of complications still have many uncertainties that could negatively impact the prognosis and patients' quality of life. Consequently, to inform clinicians about optimal treatment, we aimed to review recent advances in the understanding of the pathogenesis of AP and its diagnosis and management.

Expression of Opioid Receptors in Cells of the Immune System

The observation of the immunomodulatory effects of opioid drugs opened the discussion about possible mechanisms of action and led researchers to consider the presence of opioid receptors (OR) in cells of the immune system. To date, numerous studies analyzing the expression of OR subtypes in animal and human immune cells have been performed. Some of them confirmed the expression of OR at both the mRNA and protein level, while others did not detect the receptor mRNA either. Although this topic remains controversial, further studies are constantly being published. The most recent articles suggested that the expression level of OR in human peripheral blood lymphocytes could help to evaluate the success of methadone maintenance therapy in former opioid addicts, or could serve as a biomarker for chronic pain diagnosis. However, the applicability of these findings to clinical practice needs to be verified by further investigations.

Unintended Effects of GPCR-Targeted Drugs on the Cancer Phenotype

G protein-coupled receptors (GPCRs) are the most common class of therapeutic targets, accounting for ~35% of all FDA-approved drugs. Cancer patients receive numerous medications not only to combat cancer but also to alleviate pain, nausea, and anxiety, many of which target GPCRs. Emerging evidence has implicated GPCRs as drivers of cancer progression, therapeutic resistance, and metastasis. Therefore, the effects of commonly prescribed GPCR-targeted drugs must be reevaluated in the context of cancer. Epidemiological and experimental evidence indicate that widely used GPCR-targeted drugs may promote or inhibit cancer progression. It is crucial that we more fully understand the indirect effects of GPCR-targeted drugs on the cancer phenotype. This review summarizes recent advances in characterizing these interactions and highlights future research opportunities.

Management of Severe Acute Pancreatitis

Purpose of review

There have been significant advancements in different aspects of management of severe acute pancreatitis (SAP). Our review of the most recent literature focuses on severity prediction, fluid resuscitation, analgesic administration, nutrition, and endoscopic intervention for SAP and its extra-pancreatic complications.

Recent findings

Recent studies on serum cytokines for the prediction of SAP have shown superior prognostic performance when compared with conventional laboratory tests and clinical scoring systems. In patients with established SAP and vascular leak syndrome, intravenous fluids should be administered with caution to prevent intra-abdominal hypertension and volume overload. Endoscopic retrograde cholangiopancreatography improves outcomes only in AP patients with suspected cholangitis. Early enteral tube-feeding does not appear to be superior to on-demand oral feeding. Abdominal compartment syndrome is a highly lethal complication of SAP that requires percutaneous drainage or decompressive laparotomy. Endoscopic transmural drainage followed by necrosectomy (i.e., “step-up approach”) is the treatment strategy of choice in patients with symptomatic or infected walled-off pancreatic necrosis.

Summary

SAP is a complex clinical syndrome associated with a high mortality rate. Early prediction of SAP remains challenging due to the limited accuracy of the available prediction tools. Early fluid resuscitation, organ support, enteral nutrition, and prevention of/or prompt recognition of abdominal compartment syndrome remain cornerstones of its management. A step-up, minimally invasive drainage/debridement is the preferred approach for patients with infected pancreatic necrosis.

Nitric Oxide Stimulates Acute Pancreatitis Pain via Activating the NF-κB Signaling Pathway and Inhibiting the Kappa Opioid Receptor

Pain is the most important clinical feature of acute pancreatitis (AP); however, its specific mechanism is currently unclear. In this study, we showed that AP caused an increase in nitric oxide (NO) secretion, activated the NF-κB pathway in the dorsal root ganglia (DRGs), and caused pain. We established an AP model in vivo and tested the expression of NO, the kappa opioid receptor (KOR), and pain factors. We showed that NO in AP was significantly elevated and increased the expression of pain factors. Next, by treating DRGs in vitro, it was found that NO activated the NF-κB pathway; conversely, NF-κB had no effect on NO. Moreover, inhibition of NF-κB promoted the KOR, whereas NF-κB did not change after KOR activation. Finally, behavioral experiments showed that a NO donor increased the pain behavior of mice, while a NO scavenger, NF-κB inhibitor, or KOR agonist attenuated the pain response in mice. These results suggest that iNOS/NO/NF-κB/KOR may be a key mechanism of pain in AP, providing a theoretical basis for the use of peripheral-restricted KOR agonists for pain treatment in AP.

Impact of hereditary pancreatitis on patients and their families

Hereditary pancreatitis (HP), a highly penetrant (~80%) autosomal dominant disease associated with PRSS1 variants, causes acute pancreatitis in childhood and chronic pancreatitis by early adulthood. Other clinical features include pain, diabetes, and risk of pancreatic cancer. HP kindreds were prospectively recruited from 1995 to 2015. At enrollment, study participants completed medical and family history questionnaires, and provided samples for genotyping. Participants were recontacted between 2015 and 2017 and asked to complete a survey on concerns and experiences related to HP, PRSS1 testing, and genetic counseling. Data were analyzed with descriptive and thematic methods. Thirty-nine affected participants with HP and 21 unaffected family members completed the survey. Among unaffected family members, 'worry' and 'helplessness' were frequently described as the most difficult problem in their family because of HP, particularly with regard to pain. Three participants described the impact of drug addiction on their family. 'School or work limitations' was the leading financial concern, with 65.5% (36/55) rating it as 'moderately' or 'extremely important.' Unexpectedly, only 62% (21/34) of affected PRSS1 carriers believed the chance for a parent to pass HP to his or her children was 50%, whereas 18% (6/34) believed the chance was 100%. The impact of HP on individuals and families varied, which may reflect the highly unpredictable nature of HP severity and outcomes. Based on current and previously reported findings, an overview of important issues for genetic counselors to consider for counseling HP families is included.

Opioids Impair Intestinal Epithelial Repair in HIV-Infected Humanized Mice

Intestinal barrier dysfunction and subsequent microbial translocation play crucial roles in persistent immune activation leading to HIV disease progression. Opioid use is associated with worse outcome in HIV-infected patients. The exacerbated disease progression by opioids is mainly driven by excessive intestinal inflammation and increased gut permeability. The objective of this study is to investigate how opioids potentiate HIV disease progression by compromising intestinal barrier function and impairing intestinal epithelial self-repair mechanism. In the present study, abnormal intestinal morphology and reduced epithelial proliferation were observed in bone marrow-liver-thymus humanized mice and in HIV-infected patients who were exposed to opioids. In bone marrow-liver-thymus mice, HIV, and morphine independently, and additively induced gut dysbiosis, especially depletion of Lachnospiraceae, Ruminococcaceae, and Muribaculaceae. We also observed that the abundance of Lachnospiraceae, Ruminococcaceae, and Muribaculaceae negatively correlated with apoptosis of epithelial cells, and intestinal IL-6 levels. Previous studies have shown that these bacterial families play crucial roles in maintaining intestinal homeostasis because they include most short-chain fatty acid-producing members. Short-chain fatty acids have been shown to maintain stem cell populations and suppress inflammation in the gut by inhibiting histone deacetylases (HDAC). In addition, we demonstrate that morphine exposure inhibited growth of intestinal organoids derived from HIV transgenic mice by suppressing Notch signaling in an HDAC-dependent manner. These studies implicate an important role for HDAC in intestinal homeostasis and supports HDAC modulation as a therapeutic intervention in improving care of HIV patients, especially in opioid-abusing population.

A note on error bars as a graphical representation of the variability of data in biomedical research: Choosing between standard deviation and standard error of the mean

Standard deviation and standard error of the mean have been applied widely as error bars in scientific plots. Unfortunately, there is no universally accepted principle addressing which of these two measures should be used. Here we seek to fill this gap by outlining the reasoning for choosing standard error of the mean over standard deviation and hope to shed light on this unsettled disagreement among the biomedical community. The utility of standard error of the mean and standard deviation as error bars is further discussed by examining the figures and plots published in two research articles on pancreatic disease.

Factors Associated With Opioid Use in Patients Hospitalized for Acute Pancreatitis

IMPORTANCE

Limited guidance exists regarding the optimal approach to management of pain in acute pancreatitis (AP).

OBJECTIVES

To investigate sources of variability in opioid use for treatment of acute pain in patients hospitalized for AP and to explore a potential association of opioid prescribing patterns with length of stay.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included 4307 patients 18 years and older hospitalized for AP in a community-based integrated health care system, from January 1, 2008, to June 30, 2015. Analysis began in November 2017.

EXPOSURES

Opioid use was quantified by morphine equivalent dose (MED).

MAIN OUTCOMES AND MEASURES

Three analyses were performed: (1) factors associated with increased opioid administration during the initial 12 hours of hospitalization (baseline), (2) association of baseline opioid use with length of stay, and (3) frequency of opioid use 90 days after hospital discharge (persistent use).

RESULTS

The cohort included 4307 patients (median [interquartile range] age, 57.4 [44.0-70.2] years; 2241 women [52.0%]) with AP. At baseline, 3443 patients (79.9%) received opioids, and 388 patients (9.6%) had persistent opioid use after discharge. After adjusting for pain and other clinical factors, women received less MED than men (adjusted event ratio, 0.83; 95% CI, 0.79-0.86; P < .001). Hispanic and Asian patients received less MED than non-Hispanic white patients (adjusted event ratio, 0.85; 95% CI, 0.81-0.90; P < .001; and adjusted event ratio, 0.79; 95% CI, 0.72-0.86; P < .001, respectively). Alcohol-related AP etiology was associated with increased MED vs gallstone disorders (adjusted event ratio, 1.11; 95% CI, 1.05-1.18; P < .001). Two of 13 hospitals administered significantly less opioids compared with the others. Median (interquartile range) length of stay was independently associated with MED at baseline, with 3.0 (2.1-4.5) days among patients not receiving opioids vs 5.0 (3.2-8.7) days among patients in the highest quintile of MED (P < .001).

CONCLUSIONS AND RELEVANCE

In addition to pain and disease severity, opioid use varied by etiology of AP, sex, race/ethnicity, and institution of treatment. Increased opioid use at baseline was associated with longer hospitalization. These findings suggest opportunities for improved approaches to pain control for patients with AP.

The Impact of Morphine on the Characteristics and Function Properties of Human Mesenchymal Stem Cells

Morphine is an analgesic drug therapeutically administered to relieve pain. However, this drug has numerous side effects, which include impaired healing and regeneration after injuries or tissue damages. It suggests negative effects of morphine on stem cells which are responsible for tissue regeneration. Therefore, we studied the impact of morphine on the properties and functional characteristics of human bone marrow-derived mesenchymal stem cells (MSCs). The presence of μ-, δ- and κ-opioid receptors (OR) in untreated MSCs, and the enhanced expression of OR in MSCs pretreated with proinflammatory cytokines, was demonstrated using immunoblotting and by flow cytometry. Morphine modified in a dose-dependent manner the MSC phenotype, inhibited MSC proliferation and altered the ability of MSCs to differentiate into adipocytes or osteoblasts. Furthermore, morphine rather enhanced the expression of genes for various immunoregulatory molecules in activated MSCs, but significantly inhibited the production of the vascular endothelial growth factor, hepatocyte growth factor or leukemia inhibitory factor. All of these observations are underlying the selective impact of morphine on stem cells, and offer an explanation for the mechanisms of the negative effects of opioid drugs on stem cells and regenerative processes after morphine administration or in opioid addicts.

Opioids prevent regeneration in adult mammals through inhibition of ROS production

Inhibition of regeneration and induction of tissue fibrosis are classic outcomes of tissue repair in adult mammals. Here, using a newly developed model of regeneration in adult mammals i.e. regeneration after massive resection of an inguinal fat pad, we demonstrate that both endogenous and exogenous opioids prevent tissue regeneration in adults, by inhibiting the early production of reactive oxygen species (ROS) that generally occurs after lesion and is required for regeneration. These effects can be overcome and regeneration induced by the use of an opioid antagonist. The results obtained in both our new model and the gold standard adult zebrafish demonstrate that this mechanism can be considered as a general paradigm in vertebrates. This work clearly demonstrates that ROS is required for tissue regeneration in adult mammals and shows the deleterious effect of opioids on tissue regeneration through the control of this ROS production. It thus raises questions about opioid-based analgesia in perioperative care.