Characterizing mechanism-based pain phenotypes in patients with chronic pancreatitis: a cross-sectional analysis of the PROspective Evaluation of Chronic Pancreatitis for EpidEmiologic and Translational StuDies

Protein arginine methyltransferase-6 regulates heterogeneous nuclear ribonucleoprotein-F expression and is a potential target for the treatment of neuropathic pain

JOURNAL/nrgr/04.03/01300535-202509000-00029/figure1/v/2024-11-05T132919Z/r/image-tiff Protein arginine methyltransferase-6 participates in a range of biological functions, particularly RNA processing, transcription, chromatin remodeling, and endosomal trafficking. However, it remains unclear whether protein arginine methyltransferase-6 modifies neuropathic pain and, if so, what the mechanisms of this effect. In this study, protein arginine methyltransferase-6 expression levels and its effect on neuropathic pain were investigated in the spared nerve injury model, chronic constriction injury model and bone cancer pain model, using immunohistochemistry, western blotting, immunoprecipitation, and label-free proteomic analysis. The results showed that protein arginine methyltransferase-6 mostly co-localized with β-tubulin III in the dorsal root ganglion, and that its expression decreased following spared nerve injury, chronic constriction injury and bone cancer pain. In addition, PRMT6 knockout (Prmt6-/-) mice exhibited pain hypersensitivity. Furthermore, the development of spared nerve injury-induced hypersensitivity to mechanical pain was attenuated by blocking the decrease in protein arginine methyltransferase-6 expression. Moreover, when protein arginine methyltransferase-6 expression was downregulated in the dorsal root ganglion in mice without spared nerve injury, increased levels of phosphorylated extracellular signal-regulated kinases were observed in the ipsilateral dorsal horn, and the response to mechanical stimuli was enhanced. Mechanistically, protein arginine methyltransferase-6 appeared to contribute to spared nerve injury-induced neuropathic pain by regulating the expression of heterogeneous nuclear ribonucleoprotein-F. Additionally, protein arginine methyltransferase-6-mediated modulation of heterogeneous nuclear ribonucleoprotein-F expression required amino acids 319 to 388, but not classical H3R2 methylation. These findings indicated that protein arginine methyltransferase-6 is a potential therapeutic target for the treatment of peripheral neuropathic pain.

16. Pain in chronic pancreatitis

INTRODUCTION

Chronic pancreatitis is defined as a disease of the pancreas in which recurrent inflammatory episodes result in replacement of the pancreatic parenchyma by fibrous connective tissue in individuals with genetic, environmental, and other risk factors. Pain is one of the most important symptoms of chronic pancreatitis and, in many cases, has chronic visceral nociceptive, nociplastic, and even neuropathic components, with evidence of both central and peripheral sensitization, neuroplasticity, and neurogenic inflammation.

METHODS

The literature on the diagnosis and treatment of pain in chronic pancreatitis was reviewed and summarized.

RESULTS

Treatment of abdominal pain in chronic pancreatitis is guided by pancreatic morphology on imaging, although the correlation between pain symptoms and pathoanatomical changes is not always straightforward. Patients with pancreatic duct obstruction are initially offered endoscopic or surgical therapies, while non-obstructive disease is mostly managed medically. Lifestyle changes and psychological support are of particular importance for all chronic pancreatitis patients. Analgesic options range from non-opioid medications to opioids and adjuvant agents. Interventional pain management may consist of radiofrequency treatment of the splanchnic nerves and spinal cord stimulation. To date, there are no randomized trials supporting their efficacy in the treatment of chronic pancreatitis pain, and the recommendation to consider these treatment options is justified by evidence from observational studies. Possible opioid-sparing effects of interventional pain treatments are important to consider because opioid use and dependency are common in chronic pancreatitis patients and associated with worse outcomes. Celiac plexus block is not generally recommended for chronic pancreatitis due to the limited quality of evidence, overall short duration of effect, and invasiveness of the procedure. Central sensitization can impact the effectiveness of invasive treatments.

CONCLUSIONS

Managing pain in chronic pancreatitis is a complex task that requires a multidimensional and individualized approach. Due to the lack of randomized trials, treatment decisions are often guided by expert opinion. Integrating pharmacological and non-pharmacological interventions and collaborating with a multidisciplinary team are key components of effective chronic pancreatitis pain management.

Heterogeneity in Pancreatitis: Recognizing Heterogeneity and Its Role in the Management of Pancreatitis Summary of a National Institute of Diabetes and Digestive and Kidney Diseases Workshop

ABSTRACT

Both the clinical management and study of recurrent acute pancreatitis and chronic pancreatitis are complicated by significant heterogeneity in the etiology, mechanisms, symptoms, and complications of pancreatitis. The National Institutes of Diabetes and Digestive and Kidney Disease recently convened a workshop to address current knowledge and knowledge gaps in the field. Preclinical models that better replicate human disease are important for development of new therapies. Pain is often the most common and most difficult symptom to treat, as the causes are multifactorial and effective treatment may vary depending on whether pain is neuropathic or nociceptive in origin, and the placebo effect can complicate evaluation of the efficacy of medical and procedural interventions. Novel technologies like functional magnetic resonance imaging and virtual reality may offer novel means for assessing and treating pain, respectively. Clinical trial designs will need to consider best approaches to addressing the heterogeneity of chronic pancreatitis, including careful attention to designing eligibility criteria, and establishing accepted and validated core outcomes criteria for the field. The latter may be informed by consensus in pain research. Recruitment of participants into clinical trials has been challenging, often requiring multiple centers. Establishment of a clinical trials network would facilitate greater opportunities for therapeutic trials in pancreatitis.

Association of Serum Endocannabinoid Levels with Pancreatitis and Pancreatitis-Related Pain

Background and Aims: This investigation examined the association of pancreatitis and pancreatitis-related pain with serum levels of two endocannabinoid molecules such as anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and two paracannabinoid molecules such as oleoylethanolamide (OEA) and palmitoylethanolamide (PEA). Methods: A case-control study was conducted within the Prospective Evaluation of Chronic Pancreatitis for Epidemiological and Translational Studies, including participants with no pancreas disease (N = 56), chronic abdominal pain of suspected pancreatic origin or indeterminate chronic pancreatitis (CP) (N = 22), acute pancreatitis (N = 33), recurrent acute pancreatitis (N = 57), and definite CP (N = 63). Results: Circulating AEA concentrations were higher in women than in men (p = 0.0499), and PEA concentrations were higher in obese participants than those who were underweight/normal or overweight (p = 0.003). Asymptomatic controls with no pancreatic disease had significantly (p = 0.03) lower concentrations of AEA compared with all disease groups combined. The highest concentrations of AEA were observed in participants with acute pancreatitis, followed by those with recurrent acute pancreatitis, chronic abdominal pain/indeterminant CP, and definite CP. Participants with pancreatitis reporting abdominal pain in the past year had significantly (p = 0.04) higher concentrations of AEA compared with asymptomatic controls. Levels of 2-AG were significantly lower (p = 0.02) among participants reporting abdominal pain in the past week, and pain intensity was inversely associated with concentrations of 2-AG and OEA. Conclusions: Endocannabinoid levels may be associated with stage of pancreatitis, perhaps through activation of the CB1 receptor. Validation of our findings would support the investigation of novel therapeutics, including cannabinoid receptor-1 antagonists, in this patient population.

Pancreatitis pain quality changes at year 1 follow-up, but GP130 remains a biomarker for pain

BACKGROUND/OBJECTIVES

Debilitating abdominal pain is a common symptom affecting patients with chronic pancreatitis (CP). CP pain is dynamic due to multiple underlying mechanisms. The objective of this study was to 1) evaluate changes in pain phenotype at one year follow-up and 2) validate putative pain biomarkers in a prospective cohort study.

METHODS

The Neuropathic and Nociceptive PROMIS-PQ questionnaires were used to classify pain for participants with in the PROCEED study. Putative serum biomarkers were measured via immunoassay.

RESULTS

At enrollment, 17.6 % (120/681) subjects with CP reported no pain in the previous year. Of those, 29 % experienced pain during the 1 yr follow-up whereas 18 % of those with pain prior to enrollment reported no pain during the 1 yr follow-up period. Of the 393 subjects with PROMIS-PQ data at enrollment, 212 also had follow-up data at 1 yr. Approximately half (53.3 %) of those individuals changed pain phenotype between baseline and follow-up. At 1 yr, serum TGFβ1 level was negatively correlated with nociceptive T-scores (p = 0.006). GP130 was significantly correlated with both nociceptive (p = 0.012) and neuropathic T-scores (p = 0.043) at 1 yr, which is consistent with the previously published findings.

CONCLUSIONS

The positive association between TGFβ1 and pain is not maintained over time, suggesting it is a poor pain biomarker. However, serum GP130 is a consistent biomarker for mixed-type pain in CP. Preclinical studies show that targeting TGFβ1 or IL-6 (ligand for GP130) is sufficient to inhibit CP pain supporting further investigation of this as a potential therapeutic target.

Evaluation of Chronic Pancreatitis Prognosis Score in an American Cohort

INTRODUCTION

Chronic Pancreatitis Prognosis Score (COPPS) was developed to discriminate disease severity and predict risk for future hospitalizations. In this cohort study, we evaluated if COPPS predicts the likelihood of hospitalization(s) in an American cohort.

METHODS

The Chronic Pancreatitis, Diabetes, and Pancreatic Cancer consortium provided data and serum from subjects with chronic pancreatitis (N = 279). COPPS was calculated with baseline data and stratified by severity (low, moderate, and high). Primary endpoints included number and duration of hospitalizations during 12-month follow-up.

RESULTS

The mean ± SD COPPS was 8.4 ± 1.6. COPPS correlated with all primary outcomes: hospitalizations for any reason (number: r = 0.15, P = 0.01; duration: r = 0.16, P = 0.01) and pancreas-related hospitalizations (number: r = 0.15, P = 0.02; duration: r = 0.13, P = 0.04). The severity distribution was 13.3% low, 66.0% moderate, and 20.8% high. 37.6% of subjects had ≥1 hospitalization(s) for any reason; 32.2% had ≥1 pancreas-related hospitalizations. All primary outcomes were significantly different between severity groups: hospitalizations for any reason (number, P = 0.004; duration, P = 0.007) and pancreas-related hospitalizations (number, P = 0.02; duration, P = 0.04). The prevalence of continued drinking at follow-up ( P = 0.04) was higher in the low and moderate groups. The prevalence of anxiety at enrollment ( P = 0.02) and follow-up ( P < 0.05) was higher in the moderate and high groups.

DISCUSSION

Statistically, COPPS significantly correlated with hospitalization outcomes, but the correlations were weaker than in previous studies, which may be related to the outpatient nature of the PROspective Evaluation of Chronic Pancreatitis for EpidEmiologic and Translational StuDies cohort and lower prevalence of high severity disease. Studies in other prospective cohorts are needed to understand the full utility of COPPS as a potential tool for clinical risk assessment and intervention.

Recent advances in the understanding and management of chronic pancreatitis pain

Abdominal pain is the most common symptom of chronic pancreatitis (CP) and is often debilitating for patients and very difficult to treat. To date, there exists no cure for the disease. Treatment strategies focus on symptom management and on mitigation of disease progression by reducing toxin exposure and avoiding recurrent inflammatory events. Traditional treatment protocols start with medical management followed by consideration of procedural or surgical intervention on selected patients with severe and persistent pain. The incorporation of adjuvant therapies to treat comorbidities including psychiatric disorders, exocrine pancreatic insufficiency, mineral bone disease, frailty, and malnutrition, are in its early stages. Recent clinical studies and animal models have been designed to improve investigation into the pathophysiology of CP pain, as well as to improve pain management. Despite the array of tools available, many therapeutic options for the management of CP pain provide incomplete relief. There still remains much to discover about the neural regulation of pancreas-related pain. In this review, we will discuss research from the last 5 years that has provided new insights into novel methods of pain phenotyping and the pathophysiology of CP pain. These discoveries have led to improvements in patient selection for optimization of outcomes for both medical and procedural management, and identification of potential future therapies.

Serum Biomarkers of Nociceptive and Neuropathic Pain in Chronic Pancreatitis

Debilitating abdominal pain is a common symptom affecting most patients with chronic pancreatitis (CP). There are multiple underlying mechanisms that contribute to CP-related pain, which makes successful treatment difficult. The identification of biomarkers for subtypes of pain could provide viable targets for nonopioid interventions and the development of mechanistic approaches to pain management in CP. Nineteen inflammation- and nociception-associated proteins were measured in serum collected from 358 subjects with definite CP enrolled in PROspective Evaluation of Chronic Pancreatitis for EpidEmiologic and Translational StuDies, a prospective observational study of pancreatitis in US adult subjects. First, serum levels of putative biomarkers were compared between CP subjects with and without pain. Only platelet-derived growth factor B (PDGF-B) stood out, with levels significantly higher in the CP pain group as compared to subjects with no pain. Subjects with pain were then stratified into 4 pain subtypes (Neuropathic, Nociceptive, Mixed, and Unclassified). A comparison of putative biomarker concentration among 5 groups (no pain and 4 pain subtypes) identified unique proteins that were correlated with pain subtypes. Serum transforming growth factor beta 1 (TGFβ1) level was significantly higher in the Nociceptive pain group compared to the No pain group, suggesting that TGFβ1 may be a biomarker for nociceptive pain. The Neuropathic pain only group was too small to detect statistical differences. However, glycoprotein 130 (GP130), a coreceptor for interleukin 6, was significantly higher in the Mixed pain group compared to the groups lacking a neuropathic pain component. These data suggest that GP130 may be a biomarker for neuropathic pain in CP. PERSPECTIVE: Serum TGFβ1 and GP130 may be biomarkers for nociceptive and neuropathic CP pain, respectively. Preclinical data suggest inhibiting TGFβ1 or GP130 reduces CP pain in rodent models, indicating that additional translational and clinical studies may be warranted to develop a precision medicine approach to the management of pain in CP.