Search

Given its non-invasive nature, there is increasing interest in the use of transcutaneous vagus nerve stimulation (tVNS) across basic, translational and clinical research. Contemporaneously, tVNS can be achieved by stimulating either the auricular branch or the cervical bundle of the vagus nerve, referred to as transcutaneous auricular vagus nerve stimulation(VNS) and transcutaneous cervical VNS, respectively. In order to advance the field in a systematic manner, studies using these technologies need to adequately report sufficient methodological detail to enable comparison of results between studies, replication of studies, as well as enhancing study participant safety. We systematically reviewed the existing tVNS literature to evaluate current reporting practices. Based on this review, and consensus among participating authors, we propose a set of minimal reporting items to guide future tVNS studies. The suggested items address specific technical aspects of the device and stimulation parameters. We also cover general recommendations including inclusion and exclusion criteria for participants, outcome parameters and the detailed reporting of side effects. Furthermore, we review strategies used to identify the optimal stimulation parameters for a given research setting and summarize ongoing developments in animal research with potential implications for the application of tVNS in humans. Finally, we discuss the potential of tVNS in future research as well as the associated challenges across several disciplines in research and clinical practice.

Introduction: Enteric glial cells are important players in the control of motility, intestinal barrier integrity and inflammation. During inflammation, they switch into a reactive phenotype enabling them to release inflammatory mediators, thereby shaping the inflammatory environment. While a plethora of wellestablished in vivo models exist, cell culture models necessary to decipher the mechanistic pathways of enteric glial reactivity are less well standardized. In particular, the composition of extracellular matrices (ECM) can massively affect the experimental outcome. Considering the growing number of studies involving primary enteric glial cells, a better understanding of their homeostatic and inflammatory in vitro culture conditions is needed. Methods: We examined the impact of different ECMs on enteric glial culture purity, network morphology and immune responsiveness. Therefore, we used immunofluorescence and brightfield microscopy, as well as 3' bulk mRNA sequencing. Additionally, we compared cultured cells with in vivo enteric glial transcriptomes isolated from Sox10iCreERT2Rpl22HA/+ mice. Results: We identified Matrigel and laminin as superior over other coatings, including poly-L-ornithine, different lysines, collagens, and fibronectin, gaining the highest enteric glial purity and most extended glial networks expressing connexin-43 hemichannels allowing intercellular communication. Transcriptional analysis revealed strong similarities between enteric glia on Matrigel and laminin with enrichment of gene sets supporting neuronal differentiation, while cells on poly-L-ornithine showed enrichment related to cell proliferation. Comparing cultured and in vivo enteric glial transcriptomes revealed a 50% overlap independent of the used coating substrates. Inflammatory activation of enteric glia by IL-1b treatment showed distinct coating-dependent gene expression signatures, with an enrichment of genes related to myeloid and epithelial cell differentiation on Matrigel and laminin coatings, while poly-L-ornithine induced more gene sets related to lymphocyte differentiation. Discussion: Together, changes in morphology, differentiation and immune activation of primary enteric glial cells proved a strong effect of the ECM. We identified Matrigel and laminin as pre-eminent substrates for murine enteric glial cultures. These new insights will help to standardize and improve enteric glial culture quality and reproducibility between in vitro studies in the future, allowing a better comparison of their functional role in enteric neuroinflammation. [ABSTRACT FROM AUTHOR]

Innervation of the intestinal mucosa by the sympathetic nervous system is well described but the effects of adrenergic receptor stimulation on the intestinal epithelium remain equivocal. We therefore investigated the effect of sympathetic neuronal activation on intestinal cells in mouse models and organoid cultures, to identify the molecular routes involved. Using publicly available single-cell RNA sequencing datasets we show that the α2A isoform is the most abundant adrenergic receptor in small intestinal epithelial cells. Stimulation of this receptor with norepinephrine or a synthetic specific α2A receptor agonist promotes epithelial proliferation and stem cell function, while reducing differentiation in vivo and in intestinal organoids. In an anastomotic healing mouse model, adrenergic receptor α2A stimulation resulted in improved anastomotic healing, while surgical sympathectomy augmented anastomotic leak. Furthermore, stimulation of this receptor led to profound changes in the microbial composition, likely because of altered epithelial antimicrobial peptide secretion. Thus, we established that adrenergic receptor α2A is the molecular delegate of intestinal epithelial sympathetic activity controlling epithelial proliferation, differentiation, and host defense. Therefore, this receptor could serve as a newly identified molecular target to improve mucosal healing in intestinal inflammation and wounding. [ABSTRACT FROM AUTHOR]

Background and Purpose: ET‐1 signalling modulates intestinal motility and inflammation, but the role of ET‐1/ETB receptor signalling is poorly understood. Enteric glia modulate normal motility and inflammation. We investigated whether glial ETB signalling regulates neural‐motor pathways of intestinal motility and inflammation. Experimental Approach: We studied ETB signalling using: ETB drugs (ET‐1, SaTX, BQ788), activity‐dependent stimulation of neurons (high K+‐depolarization, EFS), gliotoxins, Tg (Ednrb‐EGFP)EP59Gsat/Mmucd mice, cell‐specific mRNA in Sox10CreERT2;Rpl22‐HAflx or ChATCre;Rpl22‐HAflx mice, Sox10CreERT2::GCaMP5g‐tdT, Wnt1Cre2::GCaMP5g‐tdT mice, muscle tension recordings, fluid‐induced peristalsis, ET‐1 expression, qPCR, western blots, 3‐D LSM‐immunofluorescence co‐labelling studies in LMMP‐CM and a postoperative ileus (POI) model of intestinal inflammation. Key Results: In the muscularis externa ETB receptor is expressed exclusively in glia. ET‐1 is expressed in RiboTag (ChAT)‐neurons, isolated ganglia and intra‐ganglionic varicose‐nerve fibres co‐labelled with peripherin or SP. ET‐1 release provides activity‐dependent glial ETB receptor modulation of Ca2+ waves in neural evoked glial responses. BQ788 reveals amplification of glial and neuronal Ca2+ responses and excitatory cholinergic contractions, sensitive to L‐NAME. Gliotoxins disrupt SaTX‐induced glial‐Ca2+ waves and prevent BQ788 amplification of contractions. The ETB receptor is linked to inhibition of contractions and peristalsis. Inflammation causes glial ETB up‐regulation, SaTX‐hypersensitivity and glial amplification of ETB signalling. In vivo BQ788 (i.p., 1 mg·kg−1) attenuates intestinal inflammation in POI. Conclusion and Implications: Enteric glial ET‐1/ETB signalling provides dual modulation of neural‐motor circuits to inhibit motility. It inhibits excitatory cholinergic and stimulates inhibitory nitrergic motor pathways. Amplification of glial ETB receptors is linked to muscularis externa inflammation and possibly pathogenic mechanisms of POI. [ABSTRACT FROM AUTHOR]

Localized abdominal surgery can lead to disruption of motility in the entire gastrointestinal tract (postoperative ileus). Intestinal macrophages produce mediators that paralyze myocytes, but it is unclear how the macrophages are activated, especially those in unmanipulated intestinal areas. Here we show that intestinal surgery activates intestinal [CD103.sup.+][CD11b.sup.+] dendritic cells (DCs) to produce interleukin-12 (IL-12). This promotes interferon-γ (IFN-γ) secretion by [CCR9.sup.+] memory T helper type 1 ([T.sub.H]1) cells which activates the macrophages. IL-12 also caused some [T.sub.H]1 cells to migrate from surgically manipulated sites through the bloodstream to unmanipulated intestinal areas where they induced ileus. Preventing T cell migration with the drug FTY720 or inhibition of IL-12, T-bet ([T.sub.H]1-specific T box transcription factor) or IFN-γ prevented postoperative ileus. [CCR9.sup.+] [T.sub.H]1 memory cells were detected in the venous blood of subjects 1 h after abdominal surgery. These findings indicate that postoperative ileus is a [T.sub.H]1 immune-mediated disease and identify potential targets for disease monitoring and therapy., Postoperative ileus is a frequent and severe complication after intestinal surgery (1-5). The bowel dysmotility associated with this condition can last for days, and it necessitates parenteral nutrition and leads [...]

]?>Mechanical trauma of the gut is an unavoidable event in abdominal surgery. Former studies demonstrated that intestinal manipulation induces a strong inflammation within the tunica muscularis. We hypothesized that mechanical strain initiates or aggravates proinflammatory responses in intestinal smooth muscle cells (iSMC) or macrophages. First, an appropriate isolation and culture method for neonatal rat iSMC was established. Purified iSMC and primary peritoneal macrophages (pMacs) were subjected to static or cyclic strain, and gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6, and IL-1[beta] was analyzed by quantitative PCR. Supernatants from stretched iSMC were transferred to untreated pMacs or contrariwise, and medium transfer-triggered inflammatory gene expression was measured in unstretched cells. Finally, we investigated the synergistic effect of static strain on LPS-induced proinflammatory gene expression. Although cyclic strain failed, static strain significantly induced iNOS, COX-2, and IL-1[beta] mRNA in iSMC. pMacs showed an increase in all inflammatory genes investigated as well as macrophage inflammatory protein (MIP)-1[alpha] and MIP-2 mRNA after static strain. Both cell entities liberated unknown mediators in response to stretch that mutually stimulated iNOS gene expression. Finally, mechanostimulation amplified LPS-induced iNOS and IL-1[beta] gene expression in iSMC as well as COX-2 and IL-6 mRNA in pMacs. In conclusion, static strain initiates proinflammatory gene expression in iSMC and pMacs and triggers a bidirectional paracrine communication between both cultured cell entities via the liberation of unknown mediators. Furthermore, static strain synergistically operates with Toll-like receptor 4 ligation in a cell-specific manner. Hence, this study demonstrates that mechanical strain functions as an immunomodulatory stimulus in abdominal cells. postoperative inflammation; Toll-like receptor doi: 10.1152/ajpgi.00452.2009.