The tachykinin neuroimmune connection in inflammatory pain

The Role of Transient Receptor Potential Vanilloid 1 in Common Diseases of the Digestive Tract and the Cardiovascular and Respiratory System

Transient receptor potential vanilloid subtype 1 (TRPV1), a member of the transient receptor potential vanilloid (TRPV) channel family, is a nonselective cation channel that is widely expressed in sensory nerve fibers and nonneuronal cells, including certain vascular endothelial cells and smooth muscle cells. The activation of TRPV1 may be involved in the regulation of various physiological functions, such as the release of inflammatory mediators in the body, gastrointestinal motility function, and temperature regulation. In recent years, a large number of studies have revealed that TRPV1 plays an important role in the physiological and pathological conditions of the digestive system, cardiovascular system, and respiratory system, but there is no systematic report on TRPV1. The objective of this review is to explain the function and effects of TRPV1 on specific diseases, such as irritable bowel syndrome, hypertension, and asthma, and to further investigate the intrinsic relationship between the expression and function of TRPV1 in those diseases to find new therapeutic targets for the cure of related diseases.

Neuroimmunoendocrine peptides on inflammed and morphologically normal appendices removed due to clinical acute appendicitis

INTRODUCTION

Despite clinical characteristics and complementary exams indicate acute appendicitis, 15% to 40% of all appendectomies result in removal of appendices with normal macro- and micromorphological aspects. Even so, manifestations of acute abdomen disappear immediately after the appendectomy, and never show back again.

OBJECTIVE

To assess changes of neuroimmunoendocrine peptides on removed appendices due to clinical presentation of acute appendicitis.

METHOD

This article presents an updated revision of acute appendicitis, based on references found on PUBMED, LILACS, MEDLINE, WHOLIS and SciELO, using key words "acute appendicitis", "neuroimmune appendicitis", "neurogenic appendicopathy", and "incidental appendectomy".

RESULTS

Fourteen neuropeptides were analyzed by different authors who suggested the presence of neurogenic appendicopathy in morphologically normal appendices removed from patients with clinical presentation suggesting acute appendicitis.

CONCLUSION

The etiopathogeny of acute appendicitis continues to be unknown, and there is a great possibility that patients with morphologically normal appendices with clinical presentation of acute appendicitis that heal after appendectomy present a neuroimmunoendocrine disease.

Immune-neuroendocrine integration at the adrenal gland: cytokine control of the adrenomedullary transcriptome

The bovine chromaffin cell represents an ideal model for the study of cell signaling to gene expression by first messengers. An abundance of GPCR, ionotropic, and growth factor receptors are expressed on these cells, and they can be obtained and studied as an abundant highly enriched cell population; importantly, this is true of no other postmitotic neuroendocrine or neuronal cell type. Chromaffin cells have now been shown to bear receptors for cytokines whose expression in the circulation is highly elevated in inflammation, including tumor necrosis factor, interferon, interleukin-1, and interleukin-6. The use of bovine-specific microarrays, and various biochemical measurements in this highly homogenous cell preparation reveals unique cohorts of distinct genes regulated by cytokines in chromaffin cells, via signaling pathways that are in some cases uniquely neuroendocrine. The transcriptomic signatures of cytokine signaling in chromaffin cells suggest that the adrenal medulla may integrate neuronal, hormonal, and immune signaling during inflammation, through induction of paracrine factors that signal to both adrenal cortex and sensory afferents of the adrenal gland, and autocrine factors, which determine the duration and type of paracrine secretory signaling that occurs in either acute or chronic inflammatory conditions.

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.

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.

Phosphatidylserine receptor in chronic pancreatitis: evidence for a macrophage independent role

OBJECTIVE

This study analyzes the role of phosphatidylserine receptor (PSR) in chronic pancreatitis.

SUMMARY BACKGROUND DATA

In chronic pancreatitis, destruction of parenchyma comes along with infiltration of lymphocytes and macrophages. The phosphatidylserine receptor is expressed on the surface of macrophages and is crucial for the recognition and engulfment of apoptotic cells. In the present study, we investigated the role of this receptor and its relation to apoptosis in chronic pancreatitis.

METHODS

The expression and localization of PSR were analyzed by Northern blot analysis, RT-PCR, Western blot analysis and immunohistochemistry. Apoptosis was detected by the TUNEL method, and the RNA protection assay (RPA) was used to compare activation of apoptosis with PSR mRNA expression levels. In addition, the molecular data were related to clinicopathological parameters.

RESULTS

PSR mRNA expression was low to absent in normal pancreatic tissue samples. In human chronic pancreatitis, increased expression of PSR mRNA was present in 12 of 29 samples (41%). Up-regulation of PSR could be confirmed by Western blot analysis. In chronic pancreatitis tissue, PSR immunoreactivity was present in all islets, in some ductal cells and in macrophages. The RNA protection assay revealed high mRNA levels of the antiapoptotic genes bcl-2 and bfl-1 (P < 0.05) in chronic pancreatitis tissues with high PSR mRNA expression. The TUNEL apoptosis in situ detection method showed positive signals in some redifferentiating acinar cells and focally in acinar cells adjacent to stromal fibroblasts in chronic pancreatitis tissue samples. The distribution pattern of PSR on pancreatic cells in chronic pancreatitis corresponded to a great extent with regions of high apoptotic activity.

CONCLUSIONS

We show for the first time the presence of PSR in chronic pancreatitis on pancreatic cells other than macrophages in regions with high apoptotic activity. The coexpression and colocalization of this gene with other apoptosis mediators suggest its involvement in apoptotic processes. However, in chronic pancreatitis PSR is not only involved in phagocytosis of apoptotic cells by macrophages.

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.

Nitrergic hyperinnervation in appendicitis and in appendices histologically classified as normal

CONTEXT

The pathogenesis of appendicitis remains poorly understood. Despite new diagnostic techniques, appendices removed from patients with suspected appendicitis often appear histologically normal on conventional examination. There is increasing evidence of involvement of the enteric nervous system in immune regulation and in inflammatory responses in the gastrointestinal system.

OBJECTIVE

To investigate the nitrergic innervation of (a) acutely inflamed appendices, (b) appendices classified as histologically normal from patients with a clinical diagnosis of appendicitis, and (c) normal control appendix specimens, using the whole-mount preparation technique.

PATIENTS AND DESIGN

Full-thickness specimens were collected from 28 acutely inflamed appendices (age range, 3.2-13.4 years), 31 histologically normal appendices removed from patients (age range, 5.7-13.6 years) with suspected appendicitis, and 23 histologically normal appendices from patients (age range, newborn to 12.1 years) undergoing elective abdominal surgery (controls). Whole-mount preparation using nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry and neuronal nitric oxide synthase immunohistochemistry were performed. The density of myenteric plexus was measured with a computerized analysis system.

RESULTS

The density of myenteric plexus in normal appendix specimens was similar to that of large bowel from the newborn period up to 3 years of age; this density decreased significantly thereafter. The myenteric plexus of normal appendix specimens from patients older than 4 years demonstrated smaller ganglia connected by thin nerve bundles, compared to larger ganglia and nerve bundles in large bowel. Significant neuronal hypertrophy was found in 55% of acutely inflamed and 41% of histologically classified normal appendix specimens. The myenteric plexus of these appendix specimens had even thicker nerve bundles connecting an increased number of ganglion cells.

CONCLUSIONS

Differences in the architecture of the myenteric plexus in patients older than 3 years suggest an altered function and motility of appendix in the early years of life. The significant increase in neuronal components of the myenteric plexus in a high proportion of acutely inflamed and histologically normal appendix specimens is unlikely to have developed during a single acute inflammatory episode. This suggests an underlying chronic abnormality as a secondary response to chronic luminal obstruction or repeated inflammatory episodes in the histologically normal appendix.

Upregulation of proinflammatory cytokines and nerve growth factor by intraplantar injection of capsaicin in rats

Capsaicin-sensitive primary afferents (CSPA) are known to be involved in nociception and neurogenic inflammation. Extensive research has been devoted to the sensory role of these fibres but less attention has been paid to their local effector function. This study aimed at gaining more insight into the molecular mechanisms underlying the neurogenic inflammation induced by this special group of afferent fibres. Different groups of rats (n = 5 in each group), either naive or subjected to selective ablation of their CSPA, received individual intraplantar injections of saline, capsaicin, its vehicle or capsaicin preceded by its antagonist, capsazepine. Acute tests for nociception were used to assess the variations of the nociceptive thresholds. Variations of the levels of proinflammatory cytokines and nerve growth factor (NGF) were measured by enzyme-linked immunosorbent assay (ELISA). Intraplantar injection of capsaicin (10 microg in 50 microl) produced a sustained thermal and mechanical hyperalgesia that peaked at 3-6 h and disappeared 24 h following the injection. Similar capsaicin injection in further groups of rats produced an early upregulation of the proinflammatory cytokines and NGF, which peaked at 30-60 min and returned to control levels within 2-5 h. Similar effects were observed following the application of either capsaicin or intense electrical stimulation on the cut end of the distal portion of the sciatic nerve. The effects of capsaicin were abolished in rats subjected to selective ablation of their CSPA. These results demonstrate that CSPA can simultaneously challenge the immune system through the release of proinflammatory mediators and the central nervous system through nociceptive signalling and can therefore serve as a common afferent pathway to both immune and nervous systems.

Growth factors in pancreatic health and disease

In this article the role of different growth factors and their receptors in the pathogenesis of chronic pancreatitis and pancreatic cancer is discussed. The expression of members of the epidermal growth factor family, the fibroblast growth factor family, the transforming growth factor-beta family, the platelet-derived growth factor family, the nerve growth factor family, the insulin-like growth factor family and their signaling receptors is presented, and a correlation of the molecular data with clinical and pathological changes is performed. A number of these growth factors and their receptors are markedly overexpressed in chronic pancreatitis and pancreatic cancer. In chronic pancreatitis, overexpression of growth factors and their receptors contributes to tissue remodeling and fibrogenesis. In contrast to chronic pancreatitis, pancreatic cancer is associated with a variety of genetic alterations, including mutations in tumor suppressor genes and cell cycle regulators. In the presence of these genetic disturbances, enhanced expression of growth factors and their receptors contributes to cell proliferation and enhances the aggressiveness of pancreatic cancer cells. In summary, growth factors and their receptors are often altered in chronic pancreatitis and pancreatic cancer and contribute to various pathogenetic aspects in these disorders.

Adaptive plasticity in tachykinin and tachykinin receptor expression after focal cerebral ischemia is differentially linked to gabaergic and glutamatergic cerebrocortical circuits and cerebrovenular endothelium

To test the hypothesis of an involvement of tachykinins in destabilization and hyperexcitation of neuronal circuits, gliosis, and neuroinflammation during cerebral ischemia, we investigated cell-specific expressional changes of the genes encoding substance P (SP), neurokinin B (NKB), and the tachykinin/neurokinin receptors (NK1, NK2, and NK3) after middle cerebral artery occlusion (MCAO) in the rat. Our analysis by quantitative in situ hybridization, immunohistochemistry, and confocal microscopy was concentrated on cerebrocortical areas that survive primary infarction but undergo secondary damage. Here, SP-encoding preprotachykinin-A and NK1 mRNA levels and SP-like immunoreactivity were transiently increased in GABAergic interneurons at 2 d after MCAO. Coincidently, MCAO caused a marked expression of SP and NK1 in a subpopulation of glutamatergic pyramidal cells, and in some neurons SP and NK1 mRNAs were coinduced. Elevated levels of the NKB-encoding preprotachykinin-B mRNA and of NKB-like immunoreactivity at 2 and 7 d after MCAO were confined to GABAergic interneurons. In parallel, the expression of NK3 was markedly downregulated in pyramidal neurons. MCAO caused transient NK1 expression in activated cerebrovenular endothelium within and adjacent to the infarct. NK1 expression was absent from activated astroglia or microglia. The differential ischemia-induced plasticity of the tachykinin system in distinct inhibitory and excitatory cerebrocortical circuits suggests that it may be involved in the balance of endogenous neuroprotection and neurotoxicity by enhancing GABAergic inhibitory circuits or by facilitating glutamate-mediated hyperexcitability. The transient induction of NK1 in cerebrovenular endothelium may contribute to ischemia-induced edema and leukocyte diapedesis. Brain tachykinin receptors are proposed as potential drug targets in stroke.

NK-1 receptor gene expression is related to pain in chronic pancreatitis

Recent theories of pathogenesis of pain in chronic pancreatitis (CP) are neuroimmune interactions of intrapancreatic nerves and inflammatory cells and increase in levels of pain neurotransmitters such as substance P (SP). This study analyzed the expression and localization of neurokinin 1 receptor (NK-1R), which binds SP, and its association with pain and inflammation in CP. Pancreatic tissues from 31 patients (22 males, nine females; mean age 45.9+/-9.4 years) with CP were evaluated. Nine normal pancreases (five males, four females; mean age 42.9+/-9.5 years) served as controls. Quantitative PCR was used to determine the NK-1R mRNA expression levels and in situ hybridization and immunohistochemistry were used to localize expression sites of NK-1R mRNA and protein, respectively. We also analyzed whether an association exists between NK-1R mRNA expression and pain and inflammation. In CP samples, in situ hybridization and immunohistochemistry localized NK-1R mRNA expression and protein mainly in the nerves, ganglia, blood vessels, inflammatory cells and occasionally in fibroblasts. In patients with mild to moderate and strong intensity of pain, NK-1R mRNA levels were increased 14- and 30-fold over controls, respectively. There was a significant relationship between NK-1R mRNA levels and intensity of pain (r=0.46, P=0.03), NK-1R mRNA and the frequency of pain (r=0.51, P=0.04), and NK-1 mRNA and duration of pain (r=0.46, P=0.01) in CP patients, but not with the degree of tissue inflammation. NK-1R signaling may be involved in the pain syndrome of CP. The expression of NK-1R in inflammatory cells and blood vessels also points to an interaction of immunoreactive substance P nerves, inflammatory cells and blood vessels, and further supports the existence of a neuroimmune interaction that probably influences the pain syndrome and chronic inflammatory changes so characteristic of CP.

Neuroimmune appendicitis

BACKGROUND

15-25% of appendices removed from patients with suspected appendicitis appear normal on histological examination. The cause of pain in such patients is unknown. Since the content of neuropeptides seems to be altered in chronic inflammation, we investigated possible changes in peptidergic innervation for substance P (SP), vasoactive intestinal peptide (VIP), and growth-associated protein-43 (GAP-43).

METHODS

Appendices classified as showing acute appendicitis, non-acute appendicitis (clinical signs of acute appendicitis, but histologically not inflamed), or normal were processed for SP, VIP, and GAP-43 immunocytochemistry. The density of SP immunostaining was assessed by digitised morphometry.

FINDINGS

31 appendix specimens were studied (16 acute, 15 non-acute). 16 specimens were used as controls. Expression of GAP-43 was increased in the non-acute appendices. We observed larger amounts of SP-immunoreactive and VIP-immunoreactive nerves in the mucosal layer of the appendix in patients with non-acute appendicitis than in controls and patients with acute appendicitis (mean % area SP-immunoreactive 0.0496 [SD 0.0113] non-acute, 0.0221 [0.0049] acute, 0.0229 [0.0068] controls). In addition, a close spatial relation between SP-immunoreactive and VIP-immunoreactive nerve fibres and lymphoid cells was detected in the outer zone of lymph follicles.

INTERPRETATION

Neuroproliferation in the appendix, in association with an increase in neurotransmitters SP and VIP, may be involved in the pathophysiology of acute right abdominal pain in the absence of an acute inflammation of the appendix. Our data, together with increasing knowledge about the way in which the nervous system and immune cells interact, suggest that neuroimmune appendicitis is a distinct pathological entity.

An experimental model of tennis elbow in rats: a study of the contribution of the nervous system

The contribution of the sensory and autonomic nervous system to experimentally induced tennis elbow or lateral epicondylalgia was investigated by analyses of the release of neuropeptides from sensory (substance P, SP, neurokinin A, NKA, calcitonin gene-related peptide, CGRP) and sympathetic (neuropeptide Y, NPY) nerves. SP, CGRP, NKA, NPY-like immunoreactivity (-LI) was studied in rats cerebrospinal fluid (CSF), plasma and perfusates (PF) from the enthesis of the extensor carpi radialis brevis (ECRB) of the right elbow at 2, 6 and 24 h following 0.01 ml injection of either complete Freund adjuvans (FA) or 2% Carrageenan (CAR). The control group was injected with 0.01 ml saline. In general the changes of neuropeptide-LI in the CSF and plasma were similar for both treated groups compared with the controls, but they were more pronounced in the FA group than the CAR. SP-, NKA-, CGRP- and NPY-LI were significantly increased to a similar degree in the perfusates of the ECRBs of the treated groups with a greater increase in SP-LI in the FA than the CAR group compared with controls. When comparing the neuropeptide-LI in the CSF, plasma and PF between the 2 treated groups, there were thus few differences found. Generally a unilateral injection with either FA or CAR into the rat ECRB induced a similar alteration in the concentration of SP-, NKA-, CGRP- and NPY-LI in the CSF, plasma and PF at 2, 6 and 24 h following injection. However, the most pronounced changes in neuropeptide-LI occurred locally in the elbow ECRBs PF in both treated groups.

Collagen crosslinks in fibromyalgia

OBJECTIVE

To determine if abnormal collagen metabolism is a characteristic of fibromyalgia.

METHODS

The diagnosis of fibromyalgia was made according to the American College of Rheumatology criteria. Skin biopsy samples were obtained from the trapezius region of 8 patients with fibromyalgia. Urine was collected under standardized conditions from 55 control subjects and 39 patients with fibromyalgia, and serum was obtained from 17 controls and 22 patients with fibromyalgia. Pyridinoline (Pyd), an indicator of connective tissue disease, and deoxypyridinoline (Dpyd), an indicator of bone degradation, both of which represent products of lysyl oxidase-mediated crosslinking in collagen, were analyzed by ion-paired and gradient high-performance liquid chromatography (HPLC) methods with fluorescence detection. Levels of hydroxyproline (Hyp), a collagen turnover marker, were also measured. The findings were related to creatinine levels, and the Pyd:Dpyd ratio was determined.

RESULTS

Highly ordered cuffs of collagen were observed around the terminal nerve fibers by electron microscopic examination of biopsy tissue from all 8 patients with fibromyalgia, but were not observed in any of the control skin samples. The Pyd:Dpyd ratios in the urine and serum and the Hyp levels in the urine were significantly lower in patients with fibromyalgia than in healthy controls.

CONCLUSION

Decreased levels of collagen crosslinking in fibromyalgia may contribute to remodeling of the extracellular matrix and collagen deposition around the nerve fibers, and may contribute to the lower pain threshold at the tender points. Analysis of altered collagen metabolism either by histologic examination on biopsy, or preferably, by HPLC analysis of collagen metabolites in urine or serum may aid in understanding more about the pathogenesis of fibromyalgia.

The effects of tachykinins on inflammatory and immune cells

The aim of this article is to provide an up-dated overview of the available information on the role played by tachykinins in recruiting/regulating the function of immune/inflammatory cells, an issue which has received considerable input from the recent availability of potent and selective antagonists for tachykinin receptors. It appears that NK1 receptors play a role in mediating the extravascular migration of granulocytes into inflamed tissues in response to various inflammatory stimuli, although this effect may not be due to the expression of NK1 receptors by granulocytes themselves. Several data also imply a role for NK1 and NK2 receptors in regulating immune function. No data are available to suggest the expression of NK3 receptors by inflammatory/immune cells. Mast cell degranulation by substance P appears to be a non-receptor dependent response which may take place in vivo during intense stimulation. An emerging concept in the field relates to the ability of certain immune cell types to synthesize and possibly release tachykinins. Immune cells could represent an additional source of tachykinins in inflamed tissues, providing a non-neurogenic tachykininergic contribution to the local inflammatory process.

Effects of adjuvant on neuropeptide-like immunoreactivity in experimentally induced temporomandibular arthritis in rats

Substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivities (-LI) were examined in cerebrospinal fluid (CSF), plasma and temporomandibular joint (TMJ) perfusates in rats 1 and 12 h after inoculation at the base of the tail (0.05 ml) or injection into the right TMJ (0.01 ml) of heat-killed Mycobacterium butyricum in paraffin oil. In the rats inoculated at the base of the tail (polyarthritic rats), there was a significant increase of CGRP-LI and NKA-LI. The changes in neuropeptide-LI were not as marked in the CSF of rats injected with adjuvant in one TMJ (monoarthritic rats) as in the polyarthritic group. Instead, the most significant changes in the monoarthritic rats were seen in the perfusates of both TMJs. The increases in SP-, NKA-, CGRP- and NPY-LI were significant for both TMJs and more pronounced than in the polyarthritic rats. The results show that inoculation of adjuvant at the base of the tail induces significant changes of neuropeptide-LI predominantly in CSF, whilst an intra-articular injection induces bilateral changes in neuropeptide-LI in joint perfusate. Therefore, two different neural mechanisms may be involved early in adjuvant-induced poly- and monoarthritis.

Involvement of substance P in ultraviolet irradiation-induced inflammation in rat skin

The possible involvement of substance P released from primary afferents in rat skin was investigated in cutaneous inflammation following ultraviolet (UV) irradiation. Recordings from c-fibres innervating the UV-exposed hindpaw skin showed long-lasting low-frequency (0.8-1.25 Hz) spontaneous activity. Spontaneously active c-fibres increased to constitute 35.3% of the total population 72 h after UV exposure. Immunohistochemical analysis of substance P-containing nerve fibres in hindpaw skin revealed a significant increase in substance P immunoreactivity 24 h after UV irradiation. Average length of substance P-immunolabelled nerve fibres was about two times higher in UV-exposed compared to control skin. UV-induced oedema was investigated in rat ears using an ear-swelling test. Intradermal injection of either peptide (Spantide) or nonpeptide (CP-96,345) substance P antagonists and epicutaneous application of CP-96,345 reduced UV-induced oedema significantly in the late phase of sunburn (> 12 h after UV exposure). The UV-induced increase in skin blood flow was investigated in hindpaw skin up to 72 h by the laser Doppler technique. Epicutaneous application of CP-96,345 reduced erythema significantly between 12 and 72 h after UV exposure. Thus, our findings suggest the involvement of neurogenic substance P as a proinflammatory mediator in the late phase of UV-induced cutaneous inflammation in rats.

Changes of protein gene product 9.5 (PGP 9.5) immunoreactive nerves in inflamed appendix

The existence of chronic appendicitis is controversial. In this prospective study, we investigated possible changes in the innervation of the appendix under different pathological conditions and correlated histological findings with clinical observation. Thirty appendectomy specimens and 14 appendices obtained from organ donors or patients who underwent right hemicolectomy were immediately fixed in Bouin's solution and processed for immunocytochemistry using an antiserum directed against the panneuronal marker protein gene product 9.5 (PGP 9.5). The density of PGP 9.5 immunostaining was evaluated by digitized morphometry. Significant differences in the density of the PGP 9.5-immunoreactive area were detected in the mucosal layer. In the nonacute appendicitis group, PGP 9.5 was increased (10.99 +/- 3.15%) as compared to acute appendicitis (3.89 +/- 1.77%) and controls (4.98 +/- 1.25%). The significant increase of PGP 9.5 in nonacute appendicitis may suggest axonal sprouting leading to hyperinnervation of the mucosa. This may be a neuronal factor in the pathophysiology of the disease and pain symptoms.

Growth-associated protein-43 and protein gene-product 9.5 innervation in human pancreas: changes in chronic pancreatitis

Growth-associated protein-43, an established marker of neuronal plasticity during development and in injury, was used to characterize innervation in the normal human pancreas and changes in chronic alcohol-induced pancreatitis by using light microscopic immunocytochemistry and computer-assisted image analysis. Immunostaining for the pan-neuronal marker protein gene-product 9.5 served as a reference for the characterization of total innervation in both groups. In normal human pancreas, strong protein gene-product 9.5 immunostaining revealed all nerve fibres in nerve trunks, all neuronal cell bodies and the entire parenchymal innervation. In contrast, growth-associated protein-43 immunoreactivity was restricted to a few nerve fibres in interlobular nerve trunks and to fine varicose nerve fibres supplying the parenchyma, blood vessels, pancreatic ducts and intrinsic ganglia. In cell bodies of intrinsic neurons, growth-associated protein-43 immunoreactivity was absent or extremely faint. In chronic pancreatitis, the protein gene-product 9.5 innervation exhibited region-specific changes. In areas with reduced parenchyma, the protein gene-product 9.5 innervation was sparse. In fibrotic regions, which are characteristic for advanced stages of chronic pancreatitis, enlarged nerve trunks showing neuroma-like formations were heavily stained for protein gene-product 9.5. In fibrotic tissue, protein gene-product 9.5-containing nerve fibres were extremely rare. The growth-associated protein-43 innervation in chronic pancreatitis was characterized by a dramatic increase, which was most pronounced in the enlarged nerve trunks. Such nerve trunks were frequently surrounded by infiltrates of immune cells, which in some cases formed follicle-like structures. Digital image analysis of adjacent sections and double fluorescence immunocytochemistry revealed that growth-associated protein-43 immunoreactivity was present in the vast majority of protein gene-product 9.5-immunoreactive nerve fibres. In contrast to the normal pancreas, a major subpopulation of intrinsic neurons immunostained for growth-associated protein-43. The expression of growth-associated protein-43 in the terminal fields of pancreatic nerve suggests that the innervation of the normal human pancreas undergoes continual and toposelective remodelling. The increase in the density of growth-associated protein-43 immunoreactive nerve fibres in enlarged nerve trunks paralleled by augmented expression of growth-associated protein-43 in intrinsic neurons and reduced parenchymal growth-associated protein-43-immunoreactive innervation underline the dramatic plasticity of pancreatic innervation in chronic pancreatitis.(ABSTRACT TRUNCATED AT 400 WORDS)

Regional specificities in the distribution, chemical phenotypes, and coexistence patterns of neuropeptide containing nerve fibres in the human anal canal

Despite the pivotal clinical significance of the human anal canal, little is known about its total and specific innervation. This study assessed the comparative distribution and histotopology of nerve fibres immunoreactive for neural markers and a variety of regulatory active neuropeptides in the human anal canal by light microscopic immunohistochemistry. Depending on the epithelial zone and region of the anal canal, the neural elements were differentially immunoreactive for the pan-neural marker protein gene product 9.5, the catecholamine marker tyrosine hydroxylase, the neuroendocrine marker chromogranin A, and various neuropeptides. Protein gene product 9.5-immunoreactive nerve fibres were ubiquitously abundant in the anal canal. In the anal transitional zone, ectopic epithelial types were supplied by the same pattern of peptidergic nerves as the respective type of epithelium in normotopic location. In the dermis of the squamous zone and in the perianal epidermis, unusual distribution patterns of nerve fibres, referred to as areas of high nerve fibre density, were encountered. Double immunohistochemistry revealed region-specific coexistence patterns of neuropeptidergic nerve fibres, and novel peptide coexistence patterns were detected in anal nerve fibres. Subsets of nerve fibres formed close spatial relationships with chromogranin A-positive neuroendocrine cells, most frequently in the anal transitional zone. Chromogranin-A positive cells were shown to be present in the epithelium of perianal eccrine sweat glands. The differential distribution, peptide phenotypes and coexistence patterns of different nerve fibre populations in the human anal canal may reflect topospecific regulatory functions of neurally released neuropeptides in health and disease.

Plasminogen activators and plasminogen activator inhibitors in connective tissues and connective tissue cells: influence of the neuropeptide substance P on expression

Tissue segments isolated from ligament, epiligament, and synovial tissues from mature female New Zealand White Rabbits were demonstrated to constitutively secrete a plasminogen activator. Several tissues were also observed to constitutively secrete a plasminogen activator inhibitor which was detected in the form of a PA-PAI complex. Heterogeneity was observed in PA and PAI activity between the different connective tissues. Heterogeneity also existed between and within the medial collateral (MCL), lateral collateral (LCL), and the anterior cruciate (ACL) ligaments. In addition to the differences in constitutive expression of PA and PAI activity, differences in the responsiveness to the neuropeptide substance P (10(-5)-10(-9) M) were also detected. This responsiveness to substance P was displayed by an increase in PA and PAI activity in the conditioned medium. The pattern of responsiveness reflected the degree of innervation of these tissues. That is, synovium and epiligament tissue were the most responsive tissues to substance P while the MCL, LCL and ACL were less responsive to the neuropeptide. Parallel results were obtained using cell culture with fibroblasts isolated from the above mentioned tissues. That is, the pattern of responsiveness was similar between cells and tissue segments. More specifically, cells isolated from both synovium and epiligament increased their both their PA (slightly) and PAI activity following exposure to substance P. This was demonstrated at both the protein and RNA level. Thus, cells within a tissue maintain their phenotype when removed from their three-dimensional matrix. These results are unique in demonstrating that normal ligament and synovial cells and tissue respond to substance P by altering the expression of PA and PAI activity. This investigation further supports the concept that innervation may be important in normal connective tissue function.

Antibody-mediated clearance of viruses from the mammalian central nervous system

The novel role of antibody in clearing virus from the central nervous system without the help of other immune effectors is an important phenomenon that has only recently been documented. Possible routes for antibodies across the blood-brain barrier and how they work in the CNS are discussed here.

Epineurial peptides: a role in neuropathic pain?

Neuropathic pain is not well understood. Although central dorsal horn remodelling is likely important in maintaining chronic neuropathic pain, afferent activity from injured nerves or ganglia may initiate these changes. It is suggested, in this review that the peripheral nerve trunk is capable of sustaining a "flare" response as observed in injured skin and other tissues. The injury response may be associated with local vasodilatation, plasma extravasation and the generation of painful local afferent activity sustained by locally originating peptidergic fibers (nervi nervorum). These fibers contain substance P, calcitonin gene-related peptide and other peptides that have been linked to nociceptive transmission. Manipulation of the local injury response of the nerve trunk by pharmacologic means may provide one strategy in the treatment of neuropathic pain.