Changes in peptidergic innervation in chronic pancreatitis

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.

Serum biomarkers for chronic pancreatitis pain patterns

OBJECTIVES

Chronic pancreatitis (CP) is associated with debilitating refractory pain. Distinct subtypes of CP pain have been previously characterized based on severity (none, mild-moderate, severe) and temporal (none, intermittent, constant) nature of pain, but no mechanism-based tools are available to guide pain management. This exploratory study was designed to determine if potential pain biomarkers could be detected in patient serum and whether they associate with specific pain patterns.

METHODS

Cytokines, chemokines, and peptides associated with nociception and pain were measured in legacy serum samples from CP patients (N = 99) enrolled in the North American Pancreatitis Studies. The unsupervised hierarchical cluster analysis was applied to cluster CP patients based on their biomarker profile. Classification and regression tree was used to assess whether these biomarkers can predict pain outcomes.

RESULTS

The hierarchical cluster analysis revealed a subset of patients with predominantly constant, mild-moderate pain exhibited elevated interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-2 (IL-2), tumor necrosis factor alpha (TNFα), and monocyte chemoattractant protein-1 (MCP1) whereas patients with higher interleukin-4 (IL-4), interleukin-8 (IL-8) and calcitonin gene related peptide (CGRP) were more likely to have severe pain. Interestingly, analyses of each individual biomarker revealed that patients with constant pain had reduced circulating TNFα and fractalkine. Patients with severe pain exhibited a significant reduction in TNFα as well as trends towards lower levels of IL-6 and substance P.

DISCUSSION

The observations from this study indicate that unique pain experiences within the chronic pancreatitis population can be associated with distinct biochemical signatures. These data indicate that further hypothesis-driven analyses combining biochemical measurements and detailed pain phenotyping could be used to develop precision approaches for pain management in patients with chronic pancreatitis.

Endoscopic and surgical treatment options for chronic pancreatitis: an imaging perspective

Chronic pancreatitis is a chronic fibro-inflammatory syndrome characterized by chronic pancreatic inflammation leading to fibrosis and scarring. Patients with this multifactorial debilitating illness often require endoscopic or surgical intervention for treatment. Radiologists play a crucial role in pre-therapeutic workup as well as post-treatment imaging of chronic pancreatitis. This review summarizes the most common surgical and endoscopic treatment options that are currently available for chronic pancreatitis, including the implications on imaging.

Human pancreatic afferent and efferent nerves: mapping and 3-D illustration of exocrine, endocrine, and adipose innervation

The pancreas consists of both the exocrine (acini and ducts) and endocrine (islets) compartments to participate in and regulate the body's digestive and metabolic activities. These activities are subjected to neural modulation, but characterization of the human pancreatic afferent and efferent nerves remains difficult because of the lack of three-dimensional (3-D) image data. Here we prepare transparent human donor pancreases for 3-D histology to reveal the pancreatic microstructure, vasculature, and innervation in a global and integrated fashion. The pancreatic neural network consists of the substance P (SP)-positive sensory (afferent) nerves, the vesicular acetylcholine transporter (VAChT)-positive parasympathetic (efferent) nerves, and the tyrosine hydroxylase (TH)-positive sympathetic (efferent) nerves. The SP⁺ afferent nerves were found residing along the basal domain of the interlobular ducts. The VAChT⁺ and TH⁺ efferent nerves were identified at the peri-acinar and perivascular spaces, which follow the blood vessels to the islets. In the intrapancreatic ganglia, the SP⁺ (scattered minority, ~7%) and VAChT⁺ neurons co-localize, suggesting a local afferent-efferent interaction. Compared with the mouse pancreas, the human pancreas differs in 1) the lack of SP⁺ afferent nerves in the islet, 2) the lower ganglionic density, and 3) the obvious presence of VAChT⁺ and TH⁺ nerves around the intralobular adipocytes. The latter implicates the neural influence on the pancreatic steatosis. Overall, our 3-D image data reveal the human pancreatic afferent and efferent innervation patterns and provide the anatomical foundation for future high-definition analyses of neural remodeling in human pancreatic diseases.NEW & NOTEWORTHY Modern three-dimensional (3-D) histology with multiplex optical signals identifies the afferent and efferent innervation patterns of human pancreas, which otherwise cannot be defined with standard histology. Our 3-D image data reveal the unexpected association of sensory and parasympathetic nerves/neurons in the intrapancreatic ganglia and identify the sympathetic and parasympathetic nerve contacts with the infiltrated adipocytes. The multiplex approach offers a new way to characterize the human pancreas in remodeling (e.g., fatty infiltration and duct lesion progression).

Calcitonin gene-related peptide and pain: a systematic review

BACKGROUND

Calcitonin gene-related peptide (CGRP) is widely distributed in nociceptive pathways in human peripheral and central nervous system and its receptors are also expressed in pain pathways. CGRP is involved in migraine pathophysiology but its role in non-headache pain has not been clarified.

METHODS

We performed a systematic literature search on PubMed, Embase and ClinicalTrials.gov for articles on CGRP and non-headache pain covering human studies including experimental studies and randomized clinical trials.

RESULTS

The literature search identified 375 citations of which 50 contained relevant original data. An association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain was found. In 13 out of 20 studies in somatic pain conditions, CGRP levels had a positive correlation with pain. Increased CGRP levels were reported in plasma, synovial and cerebrospinal fluid in subjects with musculoskeletal pain. A randomized clinical trial on monoclonal antibody, which selectively binds to and inhibits the activity of CGRP (galcanezumab) in patients with osteoarthritis knee pain, failed to demonstrate improvement of pain compared with placebo. No studies to date have investigated the efficacy of monoclonal antibodies against CGRP receptor in non-headache pain conditions.

CONCLUSION

The present review revealed the association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain. These data suggest that CGRP may act as a neuromodulator in non-headache pain conditions. However, more studies are needed to fully understand the role of CGRP in nociceptive processing and therapy of chronic pain.

The density of parasympathetic axons is reduced in the exocrine pancreas of individuals recently diagnosed with type 1 diabetes

To elucidate the etiology of type 1 diabetes, the affected pancreas needs to be thoroughly characterized. Pancreatic innervation has been suggested to be involved in the pathology of the disease and a reduction of sympathetic innervation of the islets was recently reported. In the present study, we hypothesized that parasympathetic innervation would be altered in the type 1 diabetes pancreas. Human pancreatic specimens were obtained from a unique cohort of individuals with recent onset or long standing type 1 diabetes. Density of parasympathetic axons was assessed by immunofluorescence and morphometry. Our main finding was a reduced density of parasympathetic axons in the exocrine, but not endocrine compartment of the pancreas in individuals with recent onset type 1 diabetes. The reduced density of parasympathetic axons in the exocrine compartment could have functional implications, e.g. be related to the exocrine insufficiency reported in type 1 diabetes patients. Further studies are needed to understand whether reduced parasympathetic innervation is a cause or consequence of type 1 diabetes.

Neural plasticity in pancreatitis and pancreatic cancer

Pancreatic nerves undergo prominent alterations during the evolution and progression of human chronic pancreatitis and pancreatic cancer. Intrapancreatic nerves increase in size (neural hypertrophy) and number (increased neural density). The proportion of autonomic and sensory fibres (neural remodelling) is switched, and are infiltrated by perineural inflammatory cells (pancreatic neuritis) or invaded by pancreatic cancer cells (neural invasion). These neuropathic alterations also correlate with neuropathic pain. Instead of being mere histopathological manifestations of disease progression, pancreatic neural plasticity synergizes with the enhanced excitability of sensory neurons, with Schwann cell recruitment toward cancer and with central nervous system alterations. These alterations maintain a bidirectional interaction between nerves and non-neural pancreatic cells, as demonstrated by tissue and neural damage inducing neuropathic pain, and activated neurons releasing mediators that modulate inflammation and cancer growth. Owing to the prognostic effects of pain and neural invasion in pancreatic cancer, dissecting the mechanism of pancreatic neuroplasticity holds major translational relevance. However, current in vivo models of pancreatic cancer and chronic pancreatitis contain many discrepancies from human disease that overshadow their translational value. The present Review discusses novel possibilities for mechanistically uncovering the role of the nervous system in pancreatic disease progression.

Pancreatic pain

PURPOSE OF REVIEW

Pain is the most common symptom of chronic pancreatitis, with a profound socioeconomic impact. Historical management paradigms failed, as they did not adequately address the fundamental underlying mechanisms. The present article describes the neurobiology of pain and sensitization in this condition, in an effort to explain prior failings and provide future directions for managing pain in chronic pancreatitis.

RECENT FINDINGS

A number of recent advances have been made in understanding the neurobiology of pain for this condition. This has been coupled with clinical advances in assessing sensitization to pain in these patients, which has been shown to predict response to medical and surgical therapy.

SUMMARY

Pain in chronic pancreatitis is complex. Addressing the mechanical and morphological findings in chronic pancreatitis without addressing the underlying neurobiological mechanisms is destined to fail. New advances in our understanding of the neurobiology of pain in chronic pancreatitis helps to explain prior failings and provides future direction for managing pain in patients afflicted by this disease.

Sensory nerves and pancreatitis

Sensory nerves are a kind of nerve that conduct afferent impulses from the periphery receptors to the central nervous system (CNS) and are able to release neuromediators from the activated peripheral endings. Sensory nerves are particularly important for microcirculatory response, and stimulation of pancreatic sensory nerves releases a variety of neuropeptides such as substance P (SP), calcitonin gene-related peptide (CGRP), etc., leading to neurogenic inflammation characterized as the local vasodilatation and plasma extravasation. Deactivation of sensory nerves often leads to the disturbances of pancreatic microcirculation. Pancreatitis is a common digestive disease that can lead to severe complications and even death if it goes untreated. Experimental studies in animals and tissue analysis in patients with pancreatitis have shown significant changes in sensory nerves supplying the pancreatic gland. Thus making clear the whole mechanism of pancreatitis is essential to treat and cure it. Sensory nerves may have a close correlation with the development of pancreatitis, and knowing more about the role of sensory nerve in pancreatitis is important for the treatment for pancreatitis. This review is aimed to summarize the relationship between sensory nerves and pancreatitis.

Animal models of pancreatitis: Can it be translated to human pain study?

Chronic pancreatitis affects many individuals around the world, and the study of the underlying mechanisms leading to better treatment possibilities are important tasks. Therefore, animal models are needed to illustrate the basic study of pancreatitis. Recently, animal models of acute and chronic pancreatitis have been thoroughly reviewed, but few reviews address the important aspect on the translation of animal studies to human studies. It is well known that pancreatitis is associated with epigastric pain, but the understanding regarding to mechanisms and appropriate treatment of this pain is still unclear. Using animal models to study pancreatitis associated visceral pain is difficult, however, these types of models are a unique way to reveal the mechanisms behind pancreatitis associated visceral pain. In this review, the animal models of acute, chronic and un-common pancreatitis are briefly outlined and animal models related to pancreatitis associated visceral pain are also addressed.

Perineural mast cells are specifically enriched in pancreatic neuritis and neuropathic pain in pancreatic cancer and chronic pancreatitis

BACKGROUND

Pancreatic neuritis is a histopathological hallmark of pancreatic neuropathy and correlates to abdominal neuropathic pain sensation in pancreatic adenocarcinoma (PCa) and chronic pancreatitis (CP). However, inflammatory cell subtypes that compose pancreatic neuritis and their correlation to the neuropathic pain syndrome in PCa and CP are yet unknown.

METHODS

Inflammatory cells within pancreatic neuritis lesions of patients with PCa (n = 20) and CP (n = 20) were immunolabeled and colorimetrically quantified with the pan-leukocyte marker CD45, with CD68 (macrophages), CD8 (cytotoxic T-lymphocytes), CD4 (T-helper cells), CD20 (B-lymphocytes), NCL-PC (plasma cells), neutrophil elastase, PRG2 (eosinophils), anti-mast cell (MC) tryptase and correlated to pain sensation. Perineural mast cell subtypes were analyzed by double immunolabeling with MC chymase. Expression and neural immunoreactivity of protease-activated receptor type 1 (PAR-1) and type 2 (PAR-2) were analyzed in PCa and CP and correlated to pain status of the patients.

RESULTS

In PCa and CP, nerves were predominantly infiltrated by cytotoxic T-lymphocytes (PCa: 35% of all perineural inflammatory cells, CP: 33%), macrophages (PCa: 39%, CP: 33%) and MC (PCa: 21%, CP: 27%). In both entities, neuropathic pain sensation was associated with a specific increase of perineural MC (PCa without pain: 14% vs. PCa with pain: 31%; CP without pain: 19% vs. CP with pain: 34%), not affecting the frequency of other inflammatory cell subtypes. The vast majority of these MC contained MC chymase. PAR-1 and PAR-2 expression did not correlate to the pain sensation of PCa and CP patients.

CONCLUSION

Pancreatic neuritis in PC and CP is composed of cytotoxic T-lymphocytes, macrophages and MC. The specific enrichment of MC around intrapancreatic nerves in neuropathic pain due to PCa and CP suggests the presence of MC-induced visceral hypersensitivity in the pancreas. Therefore, pancreatic and enteric neuropathies seem to share a similar type of neuro-immune interaction in the generation of visceral pain.

Substance P and neprilysin in chronic pancreatitis

BACKGROUND/AIMS

We aimed to analyze substance P (SP) and neprilysin (NEP), the membrane metallopeptidase that degrades SP, in chronic pancreatitis (CP).

METHODS

SP and NEP mRNA levels were analyzed by qRT-PCR in tissue samples from 30 patients with CP and 8 organ donors. In addition, SP serum levels were determined before and after surgery in the same patients, by means of a competitive ELISA assay. Genetic and epigenetic analyses of the NEP gene were also performed.

RESULTS

SP mRNA expression levels were higher in CP tissues compared to controls (p = 0.0152), while NEP mRNA showed no significant differences between CP and healthy subjects (p = 0.2102). In CP patients, SP serum levels correlated with those in tissue, and after surgical resection SP serum levels were reduced compared to the preoperative values. Failure of NEP to overexpress in CP tissues was associated with significant miR-128a overexpression (p = 0.02), rather than with mutations in the NEP coding region or the presence of hypermethylation sites in the NEP promoter region.

CONCLUSION

Tissue and serum levels of SP were increased in CP, while NEP levels remained unaltered. In an SP/NEP-mediated pathway, it would appear that NEP fails to provide adequate surveillance of SP levels. Failure of NEP to overexpress could be associated with miRNA regulation.

Unraveling the mystery of pain in chronic pancreatitis

Chronic pancreatitis is typically a painful condition and it can be associated with a severe burden of disease. The pathogenesis of pain in this disorder is poorly understood and its treatment has been largely empirical, often consisting of surgical or other invasive methods, with an outcome that is variable and frequently unsatisfactory. Human and experimental studies have indicated a critical role for neuronal mechanisms that result in peripheral and central sensitization. The pancreatic nociceptor seems to be significantly affected in this condition, with increased excitability associated with downregulation of potassium currents. Some of the specific molecules implicated in this process include the vanilloid receptor, TRPV1, nerve growth factor, the protease activated receptor 2 and a variety of others that are discussed in this Review. Studies have also indicated novel therapeutic targets for this condition.

Nerve growth factor modulates TRPV1 expression and function and mediates pain in chronic pancreatitis

BACKGROUND & AIMS

The pathogenesis of pain in chronic pancreatitis (CP) is poorly understood and treatment remains difficult. We hypothesized that nerve growth factor (NGF) plays a key role in this process via its effects on the transient receptor potential vanilloid 1, TRPV1.

METHODS

CP was induced by intraductal injection of trinitrobenzene sulfonic acid in rats. After 3 weeks, anti-NGF antibody or control serum was administered daily for 1 week. Pancreatic hyperalgesia was assessed by nocifensive behavioral response to electrical stimulation of the pancreas as well as by referred somatic pain assessed by von Frey filament testing. TRPV1 currents in pancreatic sensory neurons were examined by patch-clamp. The expression and function of TRPV1 in pancreas-specific nociceptors was examined by immunostaining and quantification of messenger RNA levels.

RESULTS

Blockade of NGF significantly attenuated pancreatic hyperalgesia and referred somatic pain compared with controls. It also decreased TRPV1 current density and open probability and reduced the proportion of pancreatic sensory neurons that expressed TRPV1 as well as levels of TRPV1 in these neurons.

CONCLUSIONS

These findings emphasize a key role for NGF in pancreatic pain and highlight the role it plays in the modulation of TRPV1 expression and activity in CP.

Increased sympathetic activity in chronic pancreatitis patients is associated with hyperalgesia

Pain treatment in chronic pancreatitis patients is difficult, with pain frequently relapsing or persisting. Recent studies suggest that altered central nervous system pain processing underlies the chronic pain state in these patients. There is evidence that increased sympathetic activity may also play a role in some chronic pain syndromes. This study assessed sympathetic nervous system activity and its relation to pain processing in patients with severe painful chronic pancreatitis. The authors postulated that chronic pancreatitis patients with more sympathetic activity exhibit more generalized hyperalgesia. In 16 chronic pancreatitis patients, sympathetic activity was measured via venous plasma norepinephrine (NE) levels (supine, standing). Pain processing was quantified via pressure pain tolerance thresholds (PPTs) in dermatomes T10 (pancreatic area), C5, T4, L1. Five patients showed increased supine plasma NE levels (NE ≥ 3.0 nmol/L). PPTs were lower in patients with increased NE levels (INE) compared with patients with normal NE (NNE) (means [95% confidence interval]: INE 402 kPa [286-517] versus NNE 522 kPa [444-600]; P = .042). In severe chronic pancreatitis patients, increased sympathetic activity and hyperalgesia appear associated, suggesting that sympathetic activity may also play a role in these patients' pain.

Pain mechanisms in chronic pancreatitis: of a master and his fire

BACKGROUND

Unraveling the mechanisms of pain in chronic pancreatitis (CP) remains a true challenge. The rapid development of pancreatic surgery in the twentieth century, usage of advanced molecular biological techniques, and emergence of clinician-scientists have enabled the elucidation of several mechanisms that lead to the chronic, complicated neuropathic pain syndrome in CP. However, the proper analysis of pain in CP should include three main arms of mechanisms: "peripheral nociception," "peripheral/pancreatic neuropathy and neuroplasticity," and "central neuropathy and neuroplasticity."

DISCUSSION

According to our current knowledge, pain in CP involves sustained sensitization of pancreatic peripheral nociceptors by neurotransmitters and neurotrophic factors following neural damage. This peripheral pancreatic neuropathy leads to intrapancreatic neuroplastic alterations that involve a profound switch in the autonomic innervation of the human pancreas via "neural remodeling." Furthermore, this neuropathy entails a hyperexcitability of spinal sensory second-order neurons, which are subject to modulation from the brainstem via descending facilitation. Finally, viscerosensory cortical areas react to this central sensitization via spatial reorganization and thus a central neuroplasticity. The present review summarizes the current findings in these arms of mechanisms and introduces a novel concept to consistently describe pain in CP as a "predominantly neuropathic," "mixed-type" pain.

Fate of nerves in chronic pancreatitis: Neural remodeling and pancreatic neuropathy

There is probably no other gastrointestinal disorder which is as much characterized by concomitant local, intra-organ and central neuropathic and neuroplastic alterations as chronic pancreatitis (CP). While some key features of this neuropathy have recently been elucidated, there is still no satisfying pathophysiological explanation for the generation of neuropathic pain in CP. It is becoming increasingly clear that an effective pain treatment in CP can probably not be achieved without consideration of the exact fate of intrapancreatic nerves and central neuroplastic alterations. This review is intended to illustrate the temporal and spatial alterations of intrapancreatic nerves in the course of CP. At the same time, it depicts the reciprocal relationship between these plastic changes and thus underlines the notion of a 'common fate' for all these alterations. Moreover, it points out numerous aspects of this fate that are yet to be unveiled and should therefore be subject to future investigation.

Beger's operation and the Berne modification: origin and current results

BACKGROUND/PURPOSE

The purpose of this paper is to illuminate the origin and current results of the duodenum-preserving pancreatic head resection (DPPHR) developed by Beger in the 1970s, as well as its simplified Berne modification, for patients suffering from chronic pancreatitis (CP). Indications for the procedures and their results are presented on the basis of available data.

METHODS

A selected review was made of the available data on the DPPHR developed by Beger and its modifications.

RESULTS

The organ-sparing DPPHR developed by Beger, and its modifications, provide better pain relief, better preservation of exocrine and endocrine pancreatic function, and a superior quality of life compared with the more radical pancreaticoduodenectomy (PD, with or without pylorus-preservation), once the standard treatment for patients with CP. Recently published data on the long-term follow-up of studies comparing PD to DPPHR indicate that the initial benefits of DPPHR over PD might be less pronounced in the long-run.

CONCLUSIONS

The organ-preserving DPPHR developed by Beger, and its modifications, have become established and well-evaluated surgical treatment options for patients with CP.

Pancreatic neuropathy results in "neural remodeling" and altered pancreatic innervation in chronic pancreatitis and pancreatic cancer

OBJECTIVES

Chronic pancreatitis (CP) and pancreatic cancer (PCa) are characterized by intrapancreatic neuropathic alterations, including increased neural density and hypertrophy, pancreatic neuritis and neural invasion (NI) by cancer cells in PCa. The aim of this study was to identify the influence of these neuropathic changes on the quality of pancreatic innervation, intrapancreatic glia, and visceral pain.

METHODS

Pancreatic nerve fiber qualities were characterized by immunohistochemical visualization of various markers, including those for sympathetic (tyrosine hydroxylase, TH) and cholinergic innervation (choline acetyltransferase, ChAT), as well as the glial transcription factor, Sox10, and the neuroepithelial progenitor cell marker, Nestin, in normal pancreas (NP, n=16), CP (n=20), and PCa (n=20) patients. The neural immunoreactivity scores of these markers were correlated with the severity of intrapancreatic neuropathic changes and with abdominal pain sensation of patients.

RESULTS

Pancreatic sympathetic innervation was significantly reduced in CP and PCa, whereas parasympathetic innervation did not show major changes. Nestin neuro-immunoreactivity was stronger, and Sox10-immunoreactivity was weaker in CP and PCa than in NP. Pancreatic sympathetic and cholinergic innervation was noticeably decreased in patients with severe pancreatic neuritis, NI by cancer cells, or abdominal pain. Moreover, the neural immunoreactivity for Sox10 and Nestin also varied with intrapancreatic neuropathic alterations and abdominal pain.

CONCLUSIONS

The quality of intrapancreatic nerve fibers and the activation state of intrapancreatic glia in CP and PCa are strikingly different from those in normal pancreas. This novel phenomenon of "neural remodeling" shows how pancreatic neuropathic pain and "visceral neuropathy" are associated with altered pancreatic innervation in CP and PCa.

Protective effects and anti-inflammatory pathways of exogenous calcitonin gene-related peptide in severe necrotizing pancreatitis

BACKGROUND

Microcirculatory disturbances are known to play a pivotal role in the pathogenesis of severe necrotizing pancreatitis (SNP). Calcitonin gene-related peptide (CGRP) is a vasodilatatory neuropeptide with potential anti-inflammatory effects. This study characterizes the protective effects and the anti-inflammatory pathway of exogenous CGRP in SNP.

METHODS

SNP was induced in rats using the glycodeoxycholic acid model. CGRP was injected prophylactically before or therapeutically after initiation of the disease. Pancreatic damage was assessed using intravital microscopy, histology, NF-kappaB p50/p65 electrophoretic mobility shift assay, serum cytokine assay and ICAM-1 immunohistochemistry at 6 or 12 h after the onset of disease.

RESULTS

Pancreatic microcirculatory disturbances, nuclear NF-kappaB levels and pancreatic ICAM-1 expression were increased in SNP compared to controls. After CGRP application, microcirculatory disturbances, NF-kappaB levels and pancreatic ICAM-1 expression were attenuated compared to pancreatitis alone. Moreover, pancreatic morphologic damage was significantly reduced by both prophylactic and therapeutic application of CGRP.

CONCLUSIONS

CGRP is a neuropeptide that ameliorates the development of SNP in rats and may provide new treatment options. Its anti-inflammatory effects appear to be mediated by the modulation of pancreatic microcirculation and the inflammatory cascade.

Review article: pain and chronic pancreatitis

BACKGROUND

Pain in chronic pancreatitis chronic pancreatitis is a frustrating and challenging symptom for both the patient and clinician. It is the most frequent and most significant symptom. Many patients fail the currently available conservative options and require opiates or endoscopic/surgical therapy. Aim To highlight the pathophysiology and management of chronic pancreatitis pain, with an emphasis on recent developments and future directions.

METHODS

Expert review, utilizing in addition a comprehensive search of PubMed utilizing the search terms chronic pancreatitis and pain, treatment or management and a manual search of recent conference abstracts for articles describing pain and chronic pancreatitis.

RESULTS

Pancreatic pain is heterogenous in its manifestations and pathophysiology. First-line medical options include abstinence from alcohol and tobacco, pancreatic enzymes, adjunctive agents, antioxidants, and non-opiate or low potency opiate analgesics. Failure of these options is not unusual. More potent opiates, neurolysis and endoscopic and surgical options can be considered in selected patients, but this requires appropriate expertise. New and better options are needed. Future options could include new types of pancreatic enzymes, novel antinociceptive agents nerve growth factors, mast cell-directed therapy, treatments to limit fibrinogenesis and therapies directed at the central component of pain.

CONCLUSIONS

Chronic pancreatitis pain remains difficult to treat. An approach utilizing conservative medical therapies is appropriate, with more invasive therapies reserved for failure of this conservative approach. Treatment options will continue to improve with new and novel therapies on the horizon.

Endotherapy for pain in chronic pancreatitis

Pain is the most distressing symptom of chronic pancreatitis. Although the pathogenesis of pain is still poorly understood, an increase in intraductal pressure may be the dominant factor. The management of pain can involve medical, endoscopic, neurolytic, and surgical therapies. Endotherapy includes pancreatic sphincterotomy, extraction of stones, placement of stent, and dilatation of strictures, sometimes preceded or followed by extracorporeal shock-wave lithotripsy. Several studies have now shown that endotherapy provides partial or complete relief of pancreatic pain in a majority of patients with an acceptable frequency of early and late complications. Endotherapy should now graduate from an experimental form of treatment to a realistic treatment option in patients with chronic or relapsing pain, particularly in the setting of calcific chronic pancreatitis.

Pain and chronic pancreatitis: is it the plumbing or the wiring?

Our progress in understanding the biology of chronic pancreatitis has been slow, particularly with respect to the pathogenesis of pain, the cardinal symptom. Although traditional theories have focused on anatomic changes, with interstitial and ductal hypertension as the main inciting factors for pain generation, subsequent studies have not confirmed a correlation between ductal pressure and the severity of pain or its relief after ductal decompression. Empirical approaches directed at anatomic causes are at best of marginal value. Although these phenomena are clearly associated with the disease, they are not likely the root cause of the pain. Instead, they probably are inciting factors on a background of neuronal sensitization induced by damage to the perineurium and subsequent exposure of the nerves to mediators and products of inflammation. In this review, we discuss the inherent limitations in our current therapies and try to identify new targets and approaches for the future, such as TRPV1, nerve growth factor-TrkA signaling, and perhaps protease activator receptor-2.

Limited effect of thoracoscopic splanchnicectomy in the treatment of severe chronic pancreatitis pain: a prospective long-term analysis of 75 cases

BACKGROUND

Bilateral thoracoscopic splanchnicectomy is a minimally invasive method of treating pain in patients with chronic pancreatitis. It offers good, short-term pain relief, but long-term success is difficult to predict. We analyze long-term results and identify factors predicting success of splanchnicectomy.

METHODS

A total of 75 consecutive chronic pancreatitis patients underwent bilateral thoracoscopic splanchnicectomy with long term follow-up (>or=1 year). Treatment success was analyzed using the Kaplan-Meier method, and possible predictive factors (etiology, gender, onset of pancreatitis, previous pancreatitis-related surgery, opioid use, pathology at imaging, technical success, and post-splanchnicectomy complications) via the Cox proportional hazards regression model. We compared patients with long-term pain relief, patients who failed the procedure within 1 year, and those who had pain recurrence after > 1 year. Further treatments after failed splanchnicectomy were evaluated.

RESULTS

A total of 66 patients (88%) were on continuous opioids; 47 (63%) had prior pancreatitis-related interventions. Treatment was successful in 52% of patients at 12 months, 38% at 24 months, and 28% at 48 months. At the end of follow-up, 21 patients (28%) reported pain relief, of whom 13 were completely pain free without any additional treatment. Pancreatic surgery after failed splanchnicectomy relieved pain in only 13% of patients. Technical success was the only independent factor significantly associated with successful splanchnicectomy outcome (P = .03). Preoperative opioid use showed a strong tendency to be associated with unsuccessful outcome (P = .07).

CONCLUSION

Splanchnicectomy offers prolonged (>4 years) benefit in 1 of 4 patients with severe chronic pancreatitis pain. Prior opioid use may adversely impact pain relief after splanchnicectomy.

Tailored resective pancreatic surgery for pediatric patients with chronic pancreatitis

BACKGROUND

Surgical treatment for chronic pancreatitis (CP) in children comprises predominantly nonresective draining procedures. The purpose of this study was to identify indications, techniques, and results of organ-preserving resective pancreatic procedures for pediatric CP at our institution.

PATIENTS AND METHODS

A retrospective chart review was performed of all children undergoing pancreatic surgery for CP over a period of 4 years.

RESULTS

Overall, 6 pediatric patients (3 male, 3 female, ages 7-18 years) underwent a duodenum-preserving pancreatic head resection (3), a middle segmental pancreatic resection (2), or a distal pancreatectomy (1) for CP of different etiologies (idiopathic 2, posttraumatic 2, pancreas divisum 1, situs inversus 1). No mortality or major surgical complication occurred. Mean operative time was 294 min (207-412 min) and intraoperative blood loss was 541 mL (100-1300 mL). Postoperative hospital stay was 13 days (10-18 days). No endocrine or exocrine insufficiency occurred during follow up of 46 months (25-50 m), and pain control was improved in 5 of 6 patients.

CONCLUSIONS

Tailored organ-preserving resective pancreatic surgery can be performed with low morbidity and mortality in pediatric patients with CP and not responding to conservative treatment.

Surgical approaches to chronic pancreatitis

Chronic pancreatitis (CP), a benign, inflammatory process of the pancreas, can cause severe pain, diabetes mellitus, steatorrhoea, and weight loss and often leads to a significant reduction in the quality of life. In the past decade our knowledge of the pathophysiology of CP has increased together with the number and quality of treatment options available for this disease. In addition to pharmacological and endoscopic treatment modalities, surgical drainage and resection procedures have become increasingly important since they have the potential to provide superior long-term results in patients with CP. The classical and pylorus-preserving pancreaticoduodenectomy, once the standard operations for patients with CP, have been replaced by organ-sparing procedures like the duodenum preserving pancreatic head resection and its variants. The latter allow better preservation of the exocrine and endocrine pancreatic function, and provide adequate pain relieve and improvement in the quality of life of CP patients.

Pancreatic pain

Abdominal pain is an important clinical symptom in pancreatic diseases. There is increasing evidence that pain in chronic pancreatitis and pancreatic cancer is triggered by pancreatic neuropathy. Damage to intrapancreatic nerves seems to support the maintenance and exacerbation of neuropathic pain. In chronic pancreatitis, intrapancreatic nerves are invaded by immune cells. This observation led to the hypothesis that neuro-immune interactions play a role in the pathogenesis of chronic pancreatitis and the accompanying abdominal pain syndrome. Similarly, pancreatic cancer cells infiltrate the perineurium of local nerves, which may in part explain the severe pain experienced by the patients. Furthermore, perineural invasion extending into extrapancreatic nerves may preclude curative resection and thus often leads to local recurrence. In recent years, the involvement of a variety of neurotrophins and neuropeptides in the pathogenesis of pancreatic pain was discovered. This review summarises recent data on the mechanisms of neuropathy and pain generation in pancreatic disorders.

Neurokinin-2 receptor levels correlate with intensity, frequency, and duration of pain in chronic pancreatitis

OBJECTIVE

Generation and maintenance of pain in chronic pancreatitis (CP) have been shown to be partially attributable to neuroimmune interactions, which involve neuropeptides such as substance P (SP). So far, expression of SP receptors NK-2R, NK-3R, the SP-encoding gene preprotachykinin A (PPT-A), and the SP degradation enzyme neutral endopeptidase (NEP) and their relation to pain in CP have not been determined.

METHODS

Tissue samples from patients with CP (n = 25) and from healthy donors (n = 20) were analyzed for PPT-A, NK-2R, NK-3R, and NEP expression using quantitative RT-PCR. NEP protein levels were examined by immunoblot analysis and its localization was determined using immunohistochemistry. A scoring system was used to grade the extent of fibrosis on hematoxylin and eosin- and Masson-Trichrome-stained sections. Messenger RNA levels and the extent of pain were analyzed for correlations.

RESULTS

In CP tissues, NK-2R and PPT-A expression was increased, whereas NK-3R and NEP mRNA levels were comparable with normal pancreas. Overexpression of NK-2R was related to the intensity, frequency, and duration of pain in CP patients. NK-1R and NEP expression was significantly related to the extent of fibrosis.

CONCLUSIONS

Expression of NK-2R and PPT-A is increased in CP and is associated with pain. Failure to up-regulate NEP may contribute to the disruption of the neuropeptides loop balance in CP and thus may exacerbate the severe pain syndrome.

Transient receptor potential vanilloid 1 mediates hyperalgesia and is up-regulated in rats with chronic pancreatitis

BACKGROUND & AIMS

The neurobiologic basis of pancreatic hyperalgesia in chronic pancreatitis (CP) is understood poorly and there is a need to identify novel therapeutic targets. Our aim was to study the role of the transient receptor potential vanilloid 1 (TRPV1), a key integrator of noxious stimuli, in the pathogenesis of pancreatic pain in a rat model of CP.

METHODS

CP was induced in rats by intraductal injection of trinitrobenzene sulfonic acid. TRPV1 currents in pancreas-specific DRG neurons were measured using perforated patch-clamp techniques. Reverse-transcription polymerase chain reaction was used to measure mRNA expression of TRPV1 in these neurons after laser capture microdissection. Immunofluorescence and Western blot analysis, using TRPV1-specific antibodies, also were performed. Pancreatic hyperalgesia was assessed by rat's nocifensive behavior to electrical stimulation of the pancreas.

RESULTS

CP was associated with a 4-fold increase in capsaicin-induced current density (P < .02), along with an increase in the proportion of pancreas-specific DRG neurons that responded to capsaicin (52.9% in controls vs 79.0% in CP; P < .05). CP also was associated with a significant increase in TRPV1 expression both at the messenger RNA and protein level in whole thoracic DRGs and pancreas-specific sensory neurons. Systemic administration of the TRPV1 antagonist SB-366791 markedly reduced both visceral pain behavior and referred somatic hyperalgesia in rats with CP, but not in control animals.

CONCLUSIONS

TRPV1 up-regulation and sensitization is a specific molecular mechanism contributing to hyperalgesia in CP and represents a useful target for treating pancreatic hyperalgesia caused by inflammation.

Effects of sensory denervation by neonatal capsaicin administration on experimental pancreatitis induced by dibutyltin dichloride

Increase in the number of intrapancreatic sensory nerve fibers has been implicated in the generation of pain in chronic pancreatitis. Because some sensory neurotransmitters (e.g., substance P) are known to have proinflammatory effects, we hypothesized that denervation of intrapancreatic nerves might influence not only pain generation but also inflammation. Neonatal Lewis rats were injected with capsaicin (50 mg/kg or 0 mg/kg), a neurotoxin, to induce denervation of primary sensory neurons. When rats reached 170-190 g body weight, experimental pancreatitis was induced by a single administration of dibutyltin dichloride (7 mg/mg). The severity of pancreatitis was evaluated in both groups in the acute phase (at 3 and 7 days) and chronic phase (at 28 days). At day 7, the sensory denervation induced by neonatal capsaicin administration inhibited pancreatic inflammation on both histological (determination of interstitial edema, expansion of interlobular septa and intercellular spaces, and inflammatory cell infiltration) and biochemical (intrapancreatic myeloperoxidase activity) evaluation. Furthermore, at day 28, glandular atrophy, pseudotubular complexes, and rate of fibrosis were each significantly lower in the capsaicin-pretreated group than in the vehicle-pretreated group. Our findings provide in vivo evidence that primary sensory neurons play important roles in both acute pancreatitis and chronic pancreatic inflammation with fibrosis.

Mechanisms and natural history of pain in chronic pancreatitis: a surgical perspective

Pain is a major clinical manifestation of chronic pancreatitis (CP) and a common indication for surgery in these patients. Pathogenesis of pain in CP is multifactorial and the mechanisms of pain may differ from patient to patient. This can explain why one therapeutic method of treatment of pain does not work in all patients and in different stages of the disease. Two main complimentary pathogenetic theories have been proposed to explain the mechanisms of pain in CP, the neurogenic theory and the theory of increased intraductal/intraparenchymal pressures. According to the neurogenic theory, in CP there are alterations of pancreatic/peripancreatic nerves, exposing them to noxious substances and/or activated immune cells, thereby generating pain ("neuroimmune interaction"). The other theory of intraductal/intraparenchymal hypertension suggests that pain in CP is generated as a result of increased pressures within the pancreatic ductal system and/or pancreatic parenchyma, like the pain in the classic compartment syndrome. The theory of intraductal/intraparenchymal hypertension is strongly supported by the good results of drainage procedures in the surgical management of CP. Pancreatic ischemia, oxygen-free radicals, centrally sensitized pain state, acute exacerbations of CP, development of complications from the pancreas (most commonly, pseudocysts) or adjacent organs (usually, duodenal and/or common bile duct stenosis), etc. are other possible contributing factors. Different patterns of pain have been described in idiopathic (early vs. late onset) and in alcoholic CP. Interestingly, pain is automatically relieved during the natural course of the disease in some patients (the "burn-out" phenomenon), after a relatively long time (from a few years to up to 3 decades). However, this is an unpredictable evolution for the individual patient. Therefore, surgery should be offered when pain is intense and after failure of conservative treatment. Surgical management should be individualized, depending on the particular findings of each patient. The knowledge of the pathophysiologic basis and of natural course of pain in CP is of paramount importance for the surgeon to select appropriate therapy for the individual patient with CP.

Pain in chronic pancreatitis and pancreatic cancer

Chronic, debilitating abdominal pain is arguably the most important component of chronic pancreatitis, leading to significant morbidity and disability. Attempting to treat this pain, which is too often unsuccessful, is a frustrating experience for physician and patient. Multiple studies to improve understanding of the pathophysiology that causes pain in some patients but not in others have been performed since the most recent reviews on this topic. In addition, new treatment modalities have been developed and evaluated in this population. This review discusses new advances in neuroscience and the study of visceral pain mechanisms, as well as genetic factors that may play a role. Updates of established therapies, as well as new techniques used in addressing pain from chronic pancreatitis, are reviewed. Lastly, outcome measures, which have been highly variable in this field over the years, are addressed.

Chronic pancreatitis, pseudotumors and other tumor-like lesions

Chronic pancreatitis is a fibroinflammatory disease of the pancreas. Etiologically, most cases are related to alcohol abuse and smoking. Recently, gene mutations have been identified as the cause of hereditary pancreatitis. Other chronic pancreatitis types that were defined in recent years are autoimmune pancreatitis (lymphoplasmacytic sclerosing pancreatitis) and paraduodenal pancreatitis ('groove pancreatitis', 'cystic dystrophy of heterotopic pancreas'). This review describes and discusses the main histological findings, the pathogenesis and the clinical features of the various types of chronic pancreatitis. In addition, pseudotumors and other tumor-like lesions are briefly mentioned.

Intrapancreatic axonal hyperbranching of dorsal root ganglia neurons in chronic pancreatitis model rats and its relation to pancreatic pain

OBJECTIVES

Increase in number of intrapancreatic nerve bundles has been implicated in the generation of persistent pain in chronic pancreatitis. To examine the origin of these nerve fibers and the mechanisms linking neural morphological change to pain generation, we used neuronal tracing techniques in combination with immunohistochemistry in spontaneous chronic pancreatitis in the Wistar Bonn/Kobori (WBN/Kob) rats.

METHODS

For retrograde tracing, horseradish peroxidase was injected into the pancreas, and labeled neurons in the sensory ganglia were counted. For anterograde tracing, biotinylated dextran amine was injected into the dorsal root ganglia (DRGs), and labeled intrapancreatic sensory fibers were histochemically assessed. For assessment of pain generation, we evaluated c-Fos-positive neurons in the spinal dorsal horn and behavioral changes of the animals.

RESULTS

In WBN/Kob rats, the numbers of horseradish peroxidase-labeled neurons were decreased in the DRGs, and the numbers of biotinylated dextran amine-labeled intrapancreatic nerve fibers and terminals were increased. Biotinylated dextran amine-labeled nerve fibers contained growth-associated protein 43. The number of c-Fos-positive neurons in the dorsal horn was also increased and was correlated with intrapancreatic growth-associated protein 43 immunoreactivity. Grooming behavior was reduced in WBN/Kob rats, and this reduction was facilitated by exocrine stimulation.

CONCLUSIONS

Axonal branching in DRG neurons innervating the pancreas increases in WBN/Kob rats, and these morphological changes are likely involved in pain generation in chronic pancreatitis.

Management of pain in small duct chronic pancreatitis

Small duct chronic pancreatitis (CP) is defined by a nondilated main pancreatic duct, and the morphological and clinical features of chronic pancreatitis with pain are the most prominent symptoms. Current treatment strategies are based on pain history and the location and extent of disease. Traditionally, radical pancreatic resectional procedures have been carried out for small duct CP, especially with an associated head mass of uncertain aetiology. Based on the information from five randomized trials, the duodenum-preserving pancreatic head resection and its modifications have proven to provide excellent long-term pain relief and to be superior to more radical operations. Therefore, these procedures can be considered the standard for small duct CP with head dominant disease. The longitudinal V-shaped excision of the ventral pancreas combines extensive drainage and a limited resection and offers good pain relief in diffuse small duct CP. However, long-term results and larger series are awaited for definite conclusions. Thoracoscopic splanchnicectomy and endosonography-guided celiac plexus blocks require controlled trials before their routine use. This article provides an overview about the current and evidence-based pain management in small duct CP.

Molecular and behavioral changes in nociception in a novel rat model of chronic pancreatitis for the study of pain

The approach to the management of painful chronic pancreatitis has been empirical, primarily due to the lack of information about biological mechanisms producing pain. To facilitate research into pain mechanisms, our aim was to assess a rat model of chronic pancreatitis induced by pancreatic infusion of trinitrobenzene sulfonic acid as a model of painful pancreatitis. Nociception was assessed by measuring mechanical sensitivity of the abdomen and by recording the number of nocifensive behaviors in response to electrical stimulation of the pancreas. Expression of neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP) in the thoracic dorsal root ganglia receiving input from the pancreas and nerve growth factor (NGF) in the pancreas were measured. Rats with pancreatitis exhibited marked increase in sensitivity to mechanical probing of the abdomen and increased sensitivity to noxious electrical stimulation of the pancreas. There were significant increases in NGF protein in the pancreas and in expression of neuropeptides CGRP and SP in the sensory neurons from dorsal root ganglia receiving input from the pancreas. We have established quantitative measures of referred nociception and pancreatic hyperalgesia in a rat model of chronic pancreatitis that bears histological similarities to the human disease. This model has considerable construct, face and predictive validity for the human condition. It is of importance for the study of the pathogenesis of pain in this condition and can facilitate the development of new therapeutic options.

Chronic pancreatitis of alcoholic and nonalcoholic origin

Fibroinflammatory changes to the pancreatic tissue characterize chronic pancreatitis. This article summarizes the current state of knowledge on the pathology and pathogenesis of chronic pancreatitis associated with alcohol, hereditary factors, metabolic conditions, and anatomical abnormalities. Specifically, the pathogenetic mechanisms that lead to chronic pancreatitis in patients with alcohol abuse will be discussed. In addition, brief descriptions of the features of chronic pancreatitis of nonalcoholic origin and of the pancreatic fibrosis that is not associated with symptoms of chronic pancreatitis will be given.

In vitro interactions between insulin-producing beta cells and embryonic dorsal root ganglia

OBJECTIVES

It has been suggested that the autoimmune assault in type 1 diabetes is not restricted to islet beta cells but also encompasses intraislet nervous structures. Thus, in addition to modulating islet endocrine function, the nerves may also play a direct pathogenic role in diabetes. A major problem in determining the role of neurons in islet function is to distinguish specific neural effects from those mediated through the vascular system, extrinsic hormones, and/or nutritional factors. The aim of this study was to develop an in vitro system that will enable studies on communication between 1 particular type of neuron and islet cell.

METHODS

To achieve this, we cocultured rat islets and rat embryonic dorsal root ganglia (DRG) in a 3-dimensional roller-tube system for 1 to 4 weeks.

RESULTS

We found a distinct glucose-induced insulin response throughout the culture period. This response was lower compared with islets cultured alone. DRGs survived better when they were cocultured with islet cells.

CONCLUSIONS

The roller-tube coculture system provides a novel in vitro system for exploring the interaction between different subpopulations of neurons and pancreatic beta cells. Coculture with DRG neurons reduced glucose-induced insulin release from beta cells, indicating that sensory nerve activity inhibits the insulin response.

Efficacy of main pancreatic-duct endoscopic drainage in patients with chronic pancreatitis, continuous pain, and dilated duct

BACKGROUND

The aim of endoscopic treatment in patients with chronic pancreatitis is to achieve decompression of the pancreatic duct, because duct obstruction with increased pressure within the duct is one of the leading causes of pain in these patients. The majority of patients suffer from relapsing pain, thus making it difficult to evaluate the efficacy of therapy. The outcome of endoscopic treatment on pain has been evaluated in patients with continuous pain (present for more than 1 month, at least 5 days per week, requiring daily analgesic therapy) and dilated duct.

METHODS

Of 343 patients who underwent endotherapy for chronic pancreatitis in a 15-year period, 22 (6.4%)(19 men, mean age 48 years, alcohol abuse 14) had continuous pain and a dilated pancreatic duct.

RESULTS

Endotherapy was successful in all patients, with no procedure-related mortality and only mild complications. Pain disappeared, and analgesics could be discontinued in all patients immediately after endotherapy. Six patients are pain free after a mean period of 5.5 years. One pain-free patient died after 3.4 years from myocardial infarction. Five patients were successfully endoscopically re-treated for pain relapses. Four patients underwent surgery for frequent pain relapses after a mean period of 2.5 years. Six patients were lost to follow-up.

CONCLUSIONS

Endotherapy should be considered as the initial treatment of choice in patients with chronic pancreatitis, dilated duct, and continuous pain.

[Duodenum-preserving pancreas head resection-an operative technique for retaining the organ in the treatment of chronic pancreatitis]

Chronic pancreatitis is an inflammatory disease characterized by the progressive conversion of pancreatic parenchyma to fibrous tissue. The most frequent causes are alcohol overconsumption and anatomic variants such as pancreas divisum, cholelithiasis, and individual genetic predisposition. The process of fibrosis with consecutive loss of pancreatic parenchyma leads to exocrine insufficiency and maldigestion and, in advanced stages of the disease, to diabetes mellitus. Beside exocrine and endocrine malfunction, mechanical complications occur such as the formation of pancreatic pseudocysts and duodenal and common bile duct obstruction. About 50% of patients with chronic pancreatitis need surgical intervention due to untreatable chronic pain. As recent investigations suggest that the head of the pancreas triggers the chronic inflammatory process, resection of this inflammatory mass must be regarded as pivotal in any surgical intervention. Radical techniques such as the Whipple procedure are undoubtedly successful regarding pain reduction but, even in its pylorus-preserving variant, associated with high postoperative morbidity due to a large loss of pancreatic parenchyma and the absence of duodenal passage. Thirty years ago, H.G. Beger described for the first time the technique of duodenum-preserving pancreatectomy, which better combines resection of the pancreatic head with low morbidity. Over the years, different variations of the original Beger technique (Frey, Izbicky, Berne modification) have been developed, and the excellent results obtained with these methods underline that organ-sparing techniques should be preferred in the surgical treatment of chronic pancreatitis.

Attenuation of nociception in a model of acute pancreatitis by an NK-1 antagonist

Substance P (SP) acting at the NK-1 neurokinin receptor has a well-documented role in the transmission and maintenance of nociceptive information. SP is found in the majority of fibers innervating the pancreas, and it is up-regulated after pancreatic inflammation. The aim of this study was to investigate the role of the NK-1 receptors in the maintenance of pancreatic nociception. Using a newly developed rat model of acute pancreatic nociception that persists for 1 week, the NK-1 receptor expression in the spinal cord and pancreas was examined using immunohistochemistry and Western blotting procedures. The effects of a specific NK-1 antagonist, CP99,994, on the behavioral manifestations of pancreatic nociception were determined. The antagonist was administered intraperitoneally and intrathecally to differentiate peripheral and central effects. Injection of CP-100,263, the inactive enantiomer of CP-99,994 was used as a control for nonspecific effects of the antagonist. Immunohistochemistry and Western blotting analysis revealed an up-regulation of the NK-1 receptor occurs in the pancreas but not at the spinal cord level. The NK-1 antagonist was able to attenuate the nociceptive behaviors in rats with pancreatitis when applied intraperitoneally with a short duration of effectiveness. Intrathecal application of the antagonist was ineffective. These results suggest the involvement of pancreatic NK-1 receptors in the maintenance of nociception during pancreatic inflammation.

Surgical and interventional treatment of chronic pancreatitis

The management of patients with chronic pancreatitis (CP) remains a challenging problem. Main indications for surgery are intractable pain, suspicion of malignancy, and involvement of adjacent organs. The main goal of surgical treatment is improvement of patient quality of life. The surgical treatment approach usually involves proximal pancreatic resection, but lateral pancreaticojejunal drainage may be used for large-duct disease. The newer duodenum-preserving head resections of Beger and Frey provide good pain control and preservation of pancreatic function. Thoracoscopic splanchnicectomy and the endoscopic approach await confirmatory trials to confirm their efficiency in the management of CP. Common bile duct obstruction is addressed by distal Roux-en-Y choledochojejunostomy but when combined with dudodenal obstruction must be treated by pancreatic head resection. Pancreatic ascites due to disrupted pancreatic duct should be treated by internal drainage. The approach to CP is multidisciplinary, tailoring the various therapeutic options to meet each individual patient's needs.

Trypsin mediates nociception via the proteinase-activated receptor 2: a potentially novel role in pancreatic pain

BACKGROUND & AIMS

The pathogenesis of pain in pancreatitis remains poorly understood. We hypothesized that trypsin, a key inflammatory mediator in this condition, can also activate nociceptive neurons via the proteinase-activated receptor 2.

METHODS

Double immunohistochemical staining of T8 to T12 dorsal root ganglia sections was performed with antibodies against proteinase-activated receptor 2 and vanilloid receptor 1, a marker for primary nociceptive neurons. In vivo nociceptive activity was measured by FOS immunoreactivity in thoracic spinal dorsal horn segments after intrapancreatic administration of proteinase-activated receptor 2 agonists. Pain behavior was assessed by visceromotor reflex activity in response to noxious stimulation of the pancreas with proteinase-activated receptor 2 agonists.

RESULTS

Proteinase-activated receptor 2 was expressed by virtually all nociceptive neurons in thoracic dorsal root ganglia. Intraductal trypsin, in subinflammatory concentrations, activated spinal dorsal horn neurons in a dose-dependent manner, as measured by FOS expression. Both trypsin and a proteinase-activated receptor 2-specific peptide agonist induced a behavioral pain response when infused into the pancreatic duct of awake rats. Preinfusion of the pancreatic duct with proteinase-activated receptor 2-specific activating peptide desensitized the response to trypsin.

CONCLUSIONS

Our findings suggest a novel proteinase-activated receptor 2-mediated role for trypsin in the pathogenesis of pancreatic pain and one that is independent of its inflammatory effect.