New aspects concerning ulcerative colitis and colonic carcinoma: analysis of levels of neuropeptides, neurotrophins, and TNFalpha/TNF receptor in plasma and mucosa in parallel with histological evaluation of the intestine

Non-electrophysiological techniques targeting transient receptor potential (TRP) gene of gastrointestinal tract

Transient receptor potential (TRP) channels are cation channels related to a wide range of physical and chemical stimuli, they are expressed all along the gastrointestinal system, and a myriad of diseases are often associated with aberrant expression or mutation of the TRP gene, suggesting that TRPs are promising targets for drug therapy. Therefore, a better understanding of the information of TRPs in health and disease could facilitate the development of effective drugs for the treatment of gastrointestinal diseases like IBD. But there are very few generalizations about the experimental techniques studied in this field. In view of the promise of TRP as a therapeutic target, we discuss experimental methods that can be used for TRPs including their distribution, function and interaction with other proteins, as well as some promising emerging technologies to provide experimental methods for future studies.

Nerve Growth Factor and the Role of Inflammation in Tumor Development

Nerve growth factor (NGF) plays a dual role both in inflammatory states and cancer, acting both as a pro-inflammatory and oncogenic factor and as an anti-inflammatory and pro-apoptotic mediator in a context-dependent way based on the signaling networks and its interaction with diverse cellular components within the microenvironment. This report aims to provide a summary and subsequent review of the literature on the role of NGF in regulating the inflammatory microenvironment and tumor cell growth, survival, and death. The role of NGF in inflammation and tumorigenesis as a component of the inflammatory system, its interaction with the various components of the respective microenvironments, its ability to cause epigenetic changes, and its role in the treatment of cancer have been highlighted in this paper.

Transcriptional landscape of TRPV1, TRPA1, TRPV4, and TRPM8 channels throughout human tissues

AIMS

This article aims to analyze the baseline distribution of TRPA1, TRPV1, TRPV4, and TRPM8 channels in human systems at the transcriptional level.

MAIN METHODS

Using the RNA-seq dataset from the National Center for Biotechnology Information (NCBI) gene database, we investigated and compared the transcriptional levels of TRPV1, TRPA1, TRPV4 and TRPM8 found in 95 human subjects representing 33 different tissues to determine the tissue specificity of all protein-coding genes.

KEY FINDING

In this study, we observed higher transcriptional levels for TRPV1 (duodenum), TRPA1 (Urinary bladder), TRPV4 (Kidney) and TRPM8 (Prostate) compared to the other TRPs.

SIGNIFICANCE

These channels are involved in developing inflammatory and painful pathologies and seem to participate in cancer development. This information on transcriptional levels of TRPV1, TRPA1, TRPV4 and TRPM8 in human systems may provide essential suggestions for further studies on these proteins.

Analysis of the Expression of Neurotrophins and Their Receptors in Adult Zebrafish Kidney

Neurotrophins and their receptors are involved in the development and maintenance of neuronal populations. Different reports have shown that all neurotrophin/receptor pathways can also play a role in several non-neuronal tissues in vertebrates, including the kidney. These signaling pathways are involved in different events to ensure the correct functioning of the kidney, such as growth, differentiation, and regulation of renal tubule transport. Previous studies in some fish species have identified the neurotrophins and receptors in the kidney. In this study, for the first time, we compare the expression profiles (mRNA and protein) of all neurotrophin/receptor pathways in the kidney of the adult zebrafish. We quantify the levels of mRNA by using qPCR and identify the expression pattern of each neurotrophin/receptor pathway by in situ hybridization. Next, we detect the proteins using Western blotting and immunohistochemistry. Our results show that among all neurotrophins analyzed, NT-3/TrkC is the most expressed in the glomerule and tubule and in the hematopoietic cells, similar to what has been reported in the mammalian kidney.

Fructus Mume (Wu Mei) Attenuates Acetic Acid-Induced Ulcerative Colitis by Regulating Inflammatory Cytokine, Reactive Oxygen Species, and Neuropeptide Levels in Model Rats

Ulcerative colitis (UC) is a chronic idiopathic inflammatory disorder of the large intestine. Fructus mume (FM), a natural food with nutritive and pharmaceutical value, has demonstrated therapeutic efficacy against UC. In this study, we investigated the protective effects and mechanisms of FM against UC. We induced UC in rats with 4% (v/v) acetic acid (AA), orally administered 0.7 or 0.325 g/kg FM and 0.3 g/kg sulfasalazine (SASP) for 7 days, and explored the responses the drugs elicited in the rats. We assessed the general conditions of the rats by the disease active index. We evaluated colon tissue damage macroscopically and by Hematoxylin & Eosin, Alcian Blue-periodic acid-Schiff, and Masson's staining, and explored the potential mechanisms of FM on inflammation, oxidative stress, and neuropeptides by measuring TNF-α, IL-6, IL-8, IL-10, MMP9, CXCR-1, SOD, GSH-px, MDA, ROS, SIRT3, SP, VIP, ghrelin, and 5-HT. FM treatment significantly attenuated colon damage and submucosal fibrosis compared with the model. It lowered serum proinflammatory TNF-α, IL-8, and colonic MMP9 and CXCR-1, and raised serum anti-inflammatory IL-10 levels. FM upregulated the antioxidant enzymes SOD, GSH-px, and SITR3 protein but inhibited ROS and MDA production. It downregulated colonic SP, VIP, ghrelin, and 5-HT. The beneficial effects of FM might be dose dependent. Around 0.7 g/kg FM and SASP displayed similar efficacy for treating AA-induced colitis in rats. Our results provide empirical evidence that FM protects against AA-induced UC in rats via anti-inflammatory and antioxidant mechanisms, and regulates neuropeptides; thus, FM may be a promising, safe, and efficacious alternative therapy for UC, if its efficacy can be confirmed in human trials.

Exosomal miR-29b of Gut Origin in Patients With Ulcerative Colitis Suppresses Heart Brain-Derived Neurotrophic Factor

Background and Aims: While the interplay between heart and gut in inflammatory bowel disease (IBD) has previously been noted, how the inflamed gut impairs heart function remain elusive. We hypothesized that exosomal miRNAs of gut origin induce cardiac remodeling in IBD. Our aim was to identify plasma exosomal miRNAs that not only are of diagnostic value but also contribute to cardiac remodeling in patients with ulcerative colitis (UC).

Methods: Plasma exosomes were isolated from UC patients and healthy control subjects and exosomal miRNAs were profiled by next-generation sequencing. Exosomal miR-29b levels in CCD841 CoN colon epithelial cells were detected by RT-qPCR. Exosomes packaged with miR-29b were incubated with H9c2 cells or administered to live mice.

Results: The plasma exosomal miRNA profiles of the UC patients were significantly different from that of the controls and 20 miRNAs including miR-29b were differentially expressed. In CCD841 CoN cells, TNFα, IL-1β, and H2O2 significantly elevated miR-29b in both the cells and their secreted exosomes (p < 0.01), suggesting that intestinal epithelium secrets exosomes rich in miR-29b in IBD. In H9c2 myoblast cells, miR-29b modulated multiple genes including brain-derived neurotrophic factor (BDNF). Epithelial cell-derived exosomes packaged with miR-29b also attenuated BDNF and increased cleaved caspase 3, suggestive of apoptosis. Furthermore, tail vein injection of engineered exosomes with high levels of miR-29b suppressed BDNF and augmented cleaved caspase 3 in the heart of adult mouse (p < 0.01).

Conclusion: Plasma exosomal miRNA profile could be a novel diagnostic approach for IBD. Excessive plasma exosomal miR-29b suppresses critical proteins like BDNF in IBD, leading to cardiac impairment.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

Upregulation of intestinal mucosal mast cells expressing VPAC1 in close proximity to vasoactive intestinal polypeptide in inflammatory bowel disease and murine colitis

BACKGROUND

Mast cells (MCs) and vasoactive intestinal polypeptide (VIP) have been proposed as regulators of the intestinal barrier and inflammation. Our aim was to map the distribution in inflammatory bowel disease (IBD) and murine colitis.

METHODS

MCs, VIP, and VIP-receptors (VPACs) were quantified by immunofluorescence and enzyme-immunoassay (EIA) in ileal tissues (villus epithelium (VE) and adjacent VE, ie, VE next to the follicle-associated epithelium, (FAE)) from Crohn's disease (CD; n = 16) and non-IBD patients, and in colonic specimens of ulcerative colitis (UC; n = 12) and healthy controls (HCs). In addition, VIP levels were measured in plasma from HCs, non-IBD, and IBD in remission (CD n = 30; UC n = 30). Colon, ileum, and plasma from mice with dextran sulfate sodium (DSS)-induced colitis and control mice were analyzed likewise.

KEY RESULTS

FAE-adjacent VE in ileum of CD possessed more MCs (P < 0.05) and MCs expressing VPAC1 (P < 0.05), but not VPAC2, compared to controls. Both adjacent and regular VE of CD had more MCs co-localizing/in close proximity to VIP (P < 0.05). In UC colon, more MCs (P < 0.0005), MCs close to VIP (P < 0.0005), and MCs expressing VPAC1 (P < 0.05) were found compared to controls. VIP levels were elevated in plasma from CD and UC compared to controls (P < 0.0005). Colon of DSS mice showed more MCs and MCs close to VIP (P < 0.05) compared to control mice. In vitro experiments revealed MCs expressing VPACs and internalized VIP after 120 minutes of VIP-stimulation.

CONCLUSIONS AND INFERENCES

Communication between MCs and VIP is upregulated during IBD and mice colitis. In CD patients, the epithelium next to FAE seems to be more involved than the surrounding VE, suggesting increased MC-VIP-interactions in this intestinal region.

proBDNF inhibits the proliferation and migration of OLN‑93 oligodendrocytes

In contrast with mature brain-derived neurotrophic factor (mBDNF), proBDNF induces cell apoptosis. However, the function of proBDNF in oligodendrocytes remains unclear. In the present study, the OLN-93 oligodendroglia cell line was utilized as an in vitro model to analyse the functions of proBDNF in oligodendroglia. p75NTR, sortilin and proBDNF were expressed in cultured OLN-93 cells. It was indicated that proBDNF inhibited OLN-93 cell proliferation in a dose-dependent manner as determined using the MTT assay and BrdU staining. Furthermore, proBDNF suppressed the migration of OLN-93 cells as demonstrated using the scratch assay. proBDNF also decreased cell viability and promoted apoptosis as indicated by activated cysteine-aspartic acid protease-3 (caspase-3) immunocytochemistry. Notably, anti-proBDNF treatment neutralized the effect of proBDNF and resulted in increased cell proliferation and migration and decreased apoptosis. However, these effects were not observed in the presence of recombinant p75NTR extracellular domain-human FC fusion protein and p75NTR antibody, indicating that proBDNF imparts its inhibitory effects on oligodendrocytes through the p75NTR signal pathway.

Dextran Sodium Sulphate (DSS)-Induced Colitis Alters the Expression of Neurotrophins in Smooth Muscle Cells of Rat Colon

Neurotrophins are present in the gastrointestinal tract where they participate in the survival and growth of enteric neurons, augmentation of enteric circuits, elevation of colonic myoelectrical activity and also in different aspects of colitis. Previous studies largely focused on the role of neural and mucosal neurotrophins in gut inflammation. The expression of neurotrophins in colonic smooth muscle cells (SMCs) and the interactions of this potential source with colitis has not been studied in the gut. The expression of NGF, BDNF, NT-3 and NT-4 in SMCs from longitudinal and circular muscle layers of rat colon from normal and dextran sodium sulphate (DSS)-induced colitis rats was measured by ELISA. NGF, BDNF, NT-3 and NT-4 are differentially expressed in both longitudinal and circular SMCs, where the expressions of BDNF and NT-4 proteins were greater in SMCs from the longitudinal muscle layer than from the circular muscle layer, while NGF protein expression was greater in circular SMCs and NT-3 expression was equal in cells from both muscle layers. Induction of colitis with DSS significantly alters neurotrophins expression pattern in colonic SMCs. NGF levels upregulated in circular SMCs. BDNF level was increased in DSS-induced colitis in longitudinal SMCs. NGF, NT-3 and NT-4 levels were downregulated in longitudinal SMCs of DSS-induced colitis rats' colon. Disturbances of neurotrophins expression in SMCs resulted from colitis might account for the structural and functional changes in inflammatory bowel disease (IBD) such as loss of innervation and characteristic hypercontractility of longitudinal muscle in IBD.

An Endogenous Tachykinergic NK2/NK3 Receptor Cascade System Controlling the Release of Serotonin from Colonic Mucosa

5-Hydroxytryptamine (5-HT) released from colonic mucosal enterochromaffin (EC) cells is a major signaling molecule, which participates in the pathophysiological regulation of colonic functions in gut disorder including irritable bowel syndrome (IBS), but the endogenous modulator system for the 5-HT release is not yet well elucidated. Our in vitro studies in guinea-pig colon have indicated that the cascade pathway of neuronal tachykinergic NK₃ receptors and NK₂ receptors on peptide YY (PYY)-containing endocrine L cells represents an endogenous modulator system for 5-HT release from EC cells and that melatonin, endogenous tachykinins and PYY play important roles in modulation of the release of 5-HT from EC cells via the endogenous NK₂/NK₃ receptor cascade system. This review aims at examining the potential role of the endogenous tachykinergic NK2/NK3 receptor cascade system controlling the release of 5-HT from EC cells, with special attention being paid to the pathophysiology of gut disorders including IBS.

Neonatal maternal separation increases susceptibility to experimental colitis and acute stress exposure in male mice

Experiencing early life stress can result in maladjusted stress response via dysregulation of the hypothalamic-pituitary-adrenal axis and serves as a risk factor for developing chronic pelvic pain disorders. We investigated whether neonatal maternal separation (NMS) would increase susceptibility to experimental colitis or exposure to acute or chronic stress. Male mice underwent NMS from postnatal day 1-21 and as adults were assessed for open field behavior, hindpaw sensitivity, and visceromotor response (VMR) to colorectal distension (CRD). VMR was also measured before and after treatment with intracolonic trinitrobenzene sulfonic acid (TNBS) or exposure to acute or chronic water avoidance stress (WAS). Myeloperoxidase (MPO) activity, proinflammatory gene and corticotropin-releasing factor (CRF) receptor expression were measured in distal colon. Baseline VMR was not affected by NMS, but undergoing CRD increased anxiety-like behaviors and mechanical hindpaw sensitivity of NMS mice. Treatment with TNBS dose-dependently decreased body weight and survival only in NMS mice. Following TNBS treatment, IL-6 and artemin mRNA levels were decreased in the distal colon of NMS mice, despite increased MPO activity. A single WAS exposure increased VMR during CRD in NMS mice and increased IL-6 mRNA and CRF₂ protein levels in the distal colon of naïve mice, whereas CRF₂ protein levels were heightened in NMS colon both at baseline and post-WAS exposure. Taken together, these results suggest that NMS in mice disrupts inflammatory- and stress-induced gene expression in the colon, potentially contributing towards an exaggerated response to specific stressors later in life.

Myenteric expression of nerve growth factor and the p75 neurotrophin receptor regulate axonal remodeling as a consequence of colonic inflammation in mice

Nerve growth factor (NGF) levels increase in response to inflammation of the mammalian colon. The precise cellular sources of colonic NGF synthesis, however, remain elusive. Using lines of transgenic mice that express enhanced green fluorescent protein (EGFP) under the control of the NGF promoter, we found a subpopulation of adendritic EGFP(+) neurons in the myenteric plexus. These colonic EGFP(+) neurons display positive immunostaining for calretinin but not nitric oxide synthase 1 (NOS1) two biomarkers of mouse myenteric neurons. A loss of NGF expression in null mutant postnatal mice does not affect the survival of these EGFP(+) neurons. Induction of colonic inflammation confirms local increases in NGF mRNA/protein levels, which coincide with heightened detection of EGFP by myenteric neurons. Though NOS1(+) myenteric neurons display positive immunostaining for trkA (the receptor required for NGF binding/signaling), transgenic overexpression of NGF by smooth muscle cells in the colon does not alter the survival, somal size, or axonal density of trkA-expressing NOS1(+) myenteric neurons. Mice lacking functional p75NTR (the second receptor required for NGF binding) exhibit significantly less axonal damage among NOS1(+) myenteric neurons, in response to chemically induced colonic inflammation. Likewise, trkA-expressing sympathetic axons that innervate the myenteric ganglia display less damage in the absence of p75NTR. These data are the first to implicate calretinin(+) myenteric neurons as a source of NGF in the murine colon, and that in response to colonic inflammation, increases in NGF can exaggerate damage of intrinsic NOS1(+) axons and extrinsic sympathetic axons that co-express trkA and p75NTR.

BDNF and Artemin are increased in drug-naïve non-depressed GAD patients: preliminary data

OBJECTIVE

While the role of neuronal and glial plasticity are well established in the pathophysiology of mood disorders, the pattern and measures of neuronal and glial cell line-derived neurotrophic factors are unknown in generalized anxiety disorder (GAD). The present study evaluates brain-derived neurotrophic factor (BDNF) and Artemin (ARTN) plasma levels in GAD patients.

METHODS

Fourteen drug-naïve GAD patients without major depression were enrolled and plasmatic levels of BDNF and ARTN mRNA were measured by RT-PCR, and compared to matched healthy controls.

RESULTS

The results showed an unexpected increase in mRNA levels of both BDNF and ARTN in patients with GAD, that appeared almost doubled when compared to healthy controls. In comparison, both BDNF and ARTN are reduced in patients with major depressive disorder. Further, the results are intriguing and might involve distinguishing pathophysiological pathways.

CONCLUSIONS

This is the first report of increased levels of a neurotrophic factor and of a glial cell line-derived neurotrophic factor family member in GAD patients. While further studies to confirm these results and the functional meaning in terms of pathophysiology of GAD are needed, the potential conceptual and clinical meanings are discussed.

Brain-derived neurotrophic factor enhances cholinergic contraction of longitudinal muscle of rabbit intestine via activation of phospholipase C

Brain-derived neurotrophic factor (BDNF) belongs to the neurotrophin family of proteins best known for its role in neuronal survival, differentiation, migration, and synaptic plasticity in central and peripheral neurons. BDNF is also widely expressed in nonneuronal tissues including the gastrointestinal tract. The role of BDNF in intestinal smooth muscle contractility is not well defined. The aim of this study was to identify the role of BDNF in carbachol (CCh)- and substance P (SP)-induced contraction of intestinal longitudinal smooth muscle. BDNF, selective tropomyosin-related kinase B (TrkB) receptor agonists, and pharmacological inhibitors of signaling pathways were examined for their effects on contraction of rabbit intestinal longitudinal muscle strips induced by CCh and SP. BDNF activation of intracellular signaling pathways was examined by Western blot in homogenates of muscle strips and isolated muscle cells. One-hour preincubation with BDNF enhanced intestinal muscle contraction induced by CCh but not by SP. The selective synthetic TrkB agonists LM 22A4 and 7,8-dihydroxyflavone produced similar effects to BDNF. The Trk antagonist K-252a, a TrkB antibody but not p75NTR antibody, blocked the effect of BDNF. The enhancement of CCh-induced contraction by BDNF was blocked by the phospholipase C (PLC) antagonist U73122, but not by ERK1/2 or Akt antagonists. Direct measurement in muscle strips and isolated muscle cells showed that BDNF caused phosphorylation of TrkB receptors and PLC-γ, but not ERK1/2 or Akt. We conclude that exogenous BDNF augments the CCh-induced contraction of longitudinal muscle from rabbit intestine by activating TrkB receptors and subsequent PLC activation.

Role of miR-19a targeting TNF-α in mediating ulcerative colitis

OBJECTIVE

Ulcerative colitis (UC) is a widely studied inflammatory disease associated with differential expression of genes involved in immune function, wound healing, and tissue remodeling. MicroRNAs have been reported to play a role in various cancer types. However, the mechanism of how microRNAs regulate UC remains unclear.

METHODS

In the present study, we investigated the role of miR-19a and tumor necrosis factor (TNF)-α in human colon tissues with UC and dextran sodium sulfate (DSS)-induced experimental colitis.

RESULTS

We identified that the expression of miR-19a was significantly reduced and TNF-α was remarkably increased in human colon tissue with UC. Moreover, this observation of miR-19a and TNF-α was also occurred in DSS-treated mice colitis. Further, we observed that miR-19a directly regulated TNF-α expression because miR-19a can suppress the expression of wild-type TNF-α reporter, but not the mutant form. The expression of inflammatory factors TNF-α, IL-8, and GM-GSF were significantly elevated upon application of miR-19a inhibitor.

CONCLUSION

Taken together, this study determines the levels of miR-19a and TNF-α in both DSS-induced experimental murine colitis and human UC and further demonstrates that miR-19a might directly regulate TNF-α. The findings may provide a new insight in the clinical treatment of UC.

Marked Effects of Tachykinin in Myositis Both in the Experimental Side and Contralaterally: Studies on NK-1 Receptor Expressions in an Animal Model

Muscle injury and inflammation (myositis) in a rabbit model of an unilateral muscle overuse were examined. It is unknown if the tachykinin system has a functional role in this situation. In this study, therefore, the neurokinin-1 receptor (NK-1R) expression patterns were evaluated. White blood cells, nerve fascicles, fine nerve fibers, and blood vessel walls in myositis areas showed NK-1R immunoreaction. NK-1R mRNA reactions were observable for white blood cells and blood vessel walls of these areas. NK-1R immunoreaction and NK-1R mRNA reactions were also seen for muscle fibers showing degenerative and regenerative features. There were almost no NK-1R immunoreactions in normal muscle tissue. Interestingly, marked NK-1R expressions were seen for myositis areas of both the experimental side and the contralateral nonexperimental side. EIA analyses showed that the concentration of substance P in the muscle tissue was clearly increased bilaterally at the experimental end stage, as compared to the situation for normal muscle tissue. These observations show that the tachykinin system is very much involved in the processes that occur in muscle injury/myositis. The effects can be related to proinflammatory effects and/or tissue repair. The fact that there are also marked NK-1R expressions contralaterally indicate that the tachykinin system has crossover effects.

TRPA1: A gatekeeper for inflammation

Tissue damage evokes an inflammatory response that promotes the removal of harmful stimuli, tissue repair, and protective behaviors to prevent further damage and encourage healing. However, inflammation may outlive its usefulness and become chronic. Chronic inflammation can lead to a host of diseases, including asthma, itch, rheumatoid arthritis, and colitis. Primary afferent sensory neurons that innervate target organs release inflammatory neuropeptides in the local area of tissue damage to promote vascular leakage, the recruitment of immune cells, and hypersensitivity to mechanical and thermal stimuli. TRPA1 channels are required for neuronal excitation, the release of inflammatory neuropeptides, and subsequent pain hypersensitivity. TRPA1 is also activated by the release of inflammatory agents from nonneuronal cells in the area of tissue injury or disease. This dual function of TRPA1 as a detector and instigator of inflammatory agents makes TRPA1 a gatekeeper of chronic inflammatory disorders of the skin, airways, and gastrointestinal tract.

Neuroimmune interactions in patients with inflammatory bowel diseases: disease activity and clinical behavior based on Substance P serum levels

BACKGROUND AND AIM

The neuropeptide Substance P, plays a key role in modulating neuroimmune interactions in patients with inflammatory bowel diseases. We analyzed Substance P serum levels in patients with ulcerative colitis and Crohn's disease, to detail the involvement of the neuropeptide in the pathophysiology of these disorders.

METHODS

Serum samples were collected from 61 patients with ulcerative colitis (24 with active and 37 with inactive disease), 66 patients with Crohn's disease (29 with active and 37 with inactive disease) and 45 healthy subjects, enrolled into the study. Neuropetide serum levels were measured by means of an ELISA/EIA. Associations with disease activity and patients clinical features were also taken into account.

RESULTS

Compared to controls, Substance P serum levels were significantly increased in both patients with ulcerative colitis and Crohn's disease, (p<0.001). In patients with ulcerative colitis, levels paralleled disease activity (p=0.014), and the amount of the neuropeptide was considerably decreased during clinical and endoscopic remission of the disease, (p=0.025). Conversely, median Substance P levels did not differ between patients with active and inactive Crohn's disease. However, levels of the neuropeptide were more often elevated in patients with inactive and stricturing/fistulizing Crohn's disease, (p=0.002).

CONCLUSIONS

Data underline that Substance P might exerts important immunomodulatory functions in inflammatory bowel disease. This study suggests a potential role for Substance P serum levels in monitoring intestinal inflammation in patients with inflammatory bowel disease.

CGRP1 receptor activation induces piecemeal release of protease-1 from mouse bone marrow-derived mucosal mast cells

BACKGROUND

The parasitized or inflamed gastrointestinal mucosa shows an increase in the number of mucosal mast cells (MMC) and the density of extrinsic primary afferent nerve fibers containing the neuropeptide, calcitonin gene-related peptide (CGRP). Currently, the mode of action of CGRP on MMC is unknown.

METHODS

The effects of CGRP on mouse bone marrow-derived mucosal mast cells (BMMC) were investigated by measurements of intracellular Ca(2+)[Ca(2+)](i) and release of mMCP-1.

KEY RESULTS

Bone marrow-derived mucosal mast cells responded to the application of CGRP with a single transient rise in [Ca(2+)](i). The proportion of responding cells increased concentration-dependently to a maximum of 19 ± 4% at 10(-5)mol L(-1) (mean ±SEM; C48/80 100%; EC(50)10(-8) mol L(-1) ). Preincubation with the CGRP receptor antagonist BIBN4096BS (10(-5) mol L(-1)) completely inhibited BMMC activation by CGRP [range 10(-5) to 10(-11) mol L(-1); analysis of variance (ANOVA) P < 0.001], while preincubation with LaCl(3) to block Ca(2+) entry did not affect the response (P = 0.18). The presence of the CGRP1 receptor on BMMC was confirmed by simultaneous immunofluorescent detection of RAMP1 or CRLR, the two components of the CGRP1 receptor, and mMCP-1. Application of CGRP for 1 h evoked a concentration-dependent release of mMCP-1 (at EC(50) 10% of content) but not of β-hexosaminidase and alterations in granular density indicative of piecemeal release.

CONCLUSIONS & INFERENCES

We demonstrate that BMMC express functional CGRP1 receptors and that their activation causes mobilization of Ca(2+) from intracellular stores and piecemeal release of mMCP-1. These findings support the hypothesis that the CGRP signaling from afferent nerves to MMC in the gastrointestinal wall is receptor-mediated.

Vasoactive intestinal peptide (VIP) receptor expression in monocyte-derived macrophages from COPD patients

Vasoactive intestinal peptide (VIP) is one of the most abundant molecules found in the respiratory tract. Due to its anti-inflammatory and bronchodilatatory properties, it has been proposed as a novel treatment for chronic obstructive pulmonary disease (COPD). The actions of VIP are mediated via three different G-protein-coupled receptors (VPAC1, VPAC2 and PAC1) which are expressed in the respiratory tract and on immunocompetent cells including macrophages. Alveolar macrophages (AM) are key players in the pathogenesis of COPD and contribute to the severity and progression of the disease. While VPAC1 has been reported to be elevated in subepithelial cells in smokers with chronic bronchitis, little is known about VPAC expression of AM in COPD patients. AM from COPD patients show a strong VPAC1 expression which exceeds VPAC2. A similar receptor expression pattern was also observed in lipopolysaccharide (LPS)-activated monocyte-derived macrophages (MDM) from healthy volunteers and COPD patients. VIP has been shown to down-regulate interleukin 8 (IL-8) secretion significantly in MDM after LPS stimulation. The response to VIP was similar in MDM from COPD patients and healthy volunteers. Our results indicate that VPAC1 up-regulation in macrophages is a common mechanism in response to acute and chronic pro-inflammatory stimuli. Although VPAC1 up-regulation is dominant, both receptor subtypes are necessary for optimal anti-inflammatory signaling. The high VPAC1 expression in AM may reflect the chronic pro-inflammatory environment found in the lung of COPD patients. Treatment with VIP may help to decrease the chronic inflammation in the lung of COPD patients.

Nerve growth factor as a signaling molecule for nerve cells and also for the neuroendocrine-immune systems

Nerve growth factor (NGF) is a signaling molecule, originally discovered for its role on differentiation and survival of peripheral sensory and sympathetic neurons. It has also been associated with functional activities of cells of the immune and endocrine systems. NGF biological activity is mediated by two classes of receptors: (i) p75 neurotrophin receptor (p75(NTR)), a 75 kDa glycoprotein, belonging to a superfamily of cytokine receptors including TNF receptors, and (ii) TrkA, a transmembrane tyrosine kinase of 140 kDa. Both TrkA and p75(NTR) are known to play a marked action in neurodegenerative disorders, immune-related deficits, and neuroendocrine (including adipoendocrine) mechanisms. This review focuses on these cellular events and presents a working model which attempts to explain the close interrelationships of the neuro-endocrine-immune triad via a modulatory action of NGF.

Breaking human cytomegalovirus major immediate-early gene silence by vasoactive intestinal peptide stimulation of the protein kinase A-CREB-TORC2 signaling cascade in human pluripotent embryonal NTera2 cells

The triggering mechanisms underlying reactivation of human cytomegalovirus (HCMV) in latently infected persons are unclear. During latency, HCMV major immediate-early (MIE) gene expression breaks silence to initiate viral reactivation. Using quiescently HCMV-infected human pluripotent embryonal NTera2 cells (NT2) to model HCMV reactivation, we show that vasoactive intestinal peptide (VIP), an immunomodulatory neuropeptide, immediately and dose-dependently (1 to 500 nM) activates HCMV MIE gene expression. This response requires the MIE enhancer cyclic AMP response elements (CRE). VIP quickly elevates CREB Ser133 and ATF-1 Ser63 phosphorylation levels, although the CREB Ser133 phosphorylation level is substantial at baseline. VIP does not change the level of HCMV genomes in nuclei, Oct4 (pluripotent cell marker), or hDaxx (cellular repressor of HCMV gene expression). VIP-activated MIE gene expression is mediated by cellular protein kinase A (PKA), CREB, and TORC2. VIP induces PKA-dependent TORC2 Ser171 dephosphorylation and nuclear entry, which likely enables MIE gene activation, as TORC2 S171A (devoid of Ser171 phosphorylation) exhibits enhanced nuclear entry and desilences the MIE genes in the absence of VIP stimulation. In conclusion, VIP stimulation of the PKA-CREB-TORC2 signaling cascade activates HCMV CRE-dependent MIE gene expression in quiescently infected NT2 cells. We speculate that neurohormonal stimulation via this signaling cascade is a possible means for reversing HCMV silence in vivo.