Sacral nerve stimulation enhances epithelial barrier of the rectum: results from a porcine model

Gastric and sacral electrical stimulation for motility disorders-A clinical perspective

BACKGROUND

Electrical stimulation of the gut has been investigated in recent decades with a view to treating various gastro-intestinal motility disorders including, among others, gastric electrical stimulation to relieve nausea and vomiting associated with gastroparesis and sacral neuromodulation to treat fecal incontinence and/or constipation. Although their symptomatic efficacy has been ascertained by randomized controlled trials, their mechanisms of action are not fully understood.

PURPOSE

This review summarizes the past year's literature on the mechanisms of action of gut electrical stimulation therapies, including their impact on the gut-brain axis.

Could the Microbiota Be a Predictive Factor for the Clinical Response to Probiotic Supplementation in IBS-D? A Cohort Study

BACKGROUND

Increasing evidence suggests the beneficial effects of probiotics in irritable bowel syndrome (IBS), but little is known about how they can impact the gut microbiota. Our objective was to evaluate the effects of a multistrain probiotic on IBS symptoms, gut permeability and gut microbiota in patients with diarrhoea-predominant IBS (IBS-D).

METHODS

Adults with IBS-D were enrolled in an open-label trial to receive a multistrain probiotic for 4 weeks. Abdominal pain, stool frequency, quality of life, gut permeability, and the luminal and adherent microbiota from colonic biopsies were evaluated before and after supplementation.

RESULTS

Probiotics significantly improved symptoms and quality of life, despite having no impact on permeability in the global population. In the population stratified by the response, the diarrhoea responders displayed reduced colonic permeability after supplementation. The luminal and adherent microbiota were specifically altered depending on the patients' clinical responses regarding pain and diarrhoea. Interestingly, we identified a microbial signature in IBS-D patients that could predict a response or lack of response to supplementation.

CONCLUSIONS

The multistrain probiotic improved the symptoms of IBS-D patients and induced distinct effects on the gut microbiota according to the patient's clinical response and initial microbiota composition. Our study further supports the need to develop individualised probiotic-based approaches regarding IBS.

Management of solitary rectal ulcer syndome: Results of a french national survey: Société Nationale Française de Coloproctologie SNFCP, France

There is no consensus on the treatment for solitary rectal ulcer syndrome (SRUS). This study aimed to obtain information from physicians treating patients with SRUS in a French medical surgical society to facilitate management plans and to develop a support algorithm. Members of the French National Society of Coloproctology (SNFCP) were invited to complete a survey that included twenty items about therapeutic management and healing criteria. Overall, 91 practitioners (median age: 52 [42-59] years) responded to the questionnaire; 64/91 (70.3%) were proctologists, and 27/91 (29.7%) were colorectal surgeons. Only 15 members (16.5%) followed more than 5 patients with SRUS per year. The therapeutic objectives were to improve both patient symptoms (100%) and quality of life (98.9%). Laxative treatment and first-line rehabilitation were agreed upon by 83.5% and 73% of the respondents, respectively. Surgery, mainly rectopexy, was offered after failed medical treatment by 81.1% of the practitioners (79.1%). The first-line strategy preferred by the professionals included laxatives and biofeedback rehabilitation. Surgical treatment, preferably rectopexy, was proposed as a second intervention. No consensus was reached regarding other therapeutic alternatives, and additional studies are required to clarify their indications.

A Novel High-Density Electromyography Probe for Evaluating Anorectal Neurophysiology: Design, Human Feasibility Study, and Validation with Trans-Sacral Magnetic Stimulation

Fecal incontinence (FI) substantially impairs quality of life and imparts a major socioeconomic burden. Anal sphincter injury and possibly pudendal nerve damage are considered common causes, however, current clinical methods for evaluating their function remain suboptimal. Electromyography (EMG) and pudendal nerve terminal latencies have been applied with some success, but are not considered standard practice due to uncertain accuracy and clinical value. In this study we developed and applied a novel anorectal high-density (HD) EMG probe in humans and pigs to acquire quantitative electrophysiological metrics of the anorectum. In the human trial we assessed somatic pathways and showed that EMG amplitude was greater for tight voluntary squeezes than light voluntary squeezes (0.03 ± 0.02 mV vs. 0.05 ± 0.03 mV). In a porcine model we applied trans-sacral magnetic stimulation to evoke extrinsically activated involuntary pathways and the resulting motor evoked potentials (MEP) were captured using the HD-EMG probe. The mean MEP amplitude at 50% magnetic stimulation intensity output (MSO) was significantly lower that the MEP amplitude at 85, 95 and 100% MSO (1.52 ± 0.50 mV vs. 3.10 ± 0.60 mV). In conclusion, the use of HD-EMG probe in conjunction with trans-sacral magnetic stimulation, for spatiotemporal mapping of anorectal EMG and MEP activity is anticipated to achieve new insights into FI and could offer improved diagnostic and prognostic biomarkers for anorectal dysfunction.

Potential of Electrical Neuromodulation for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a common chronic inflammatory disease of the digestive tract that is often debilitating. It affects patients' quality of life and imposes a financial burden. Despite advances in treatment with medications such as biologics, a large proportion of patients do not respond to medical therapy or develop adverse events. Therefore, alternative treatment options such as electrical neuromodulation are currently being investigated. Electrical neuromodulation, also called bioelectronic medicine, is emerging as a potential new treatment for IBD. Over the past decade, advancements have been made in electrical neuromodulation. A number of electrical neuromodulation methods, such as vagus nerve stimulation, sacral nerve stimulation, and tibial nerve stimulation, have been tested to treat IBD. A series of animal and clinical trials have been performed to evaluate efficacy with promising results. Although the exact underlying mechanisms of action for electrical neuromodulation remain to be explored, this modality is promising. Further randomized controlled trials and basic experiments are needed to investigate efficacy and clarify intrinsic mechanisms.

Anti-inflammatory effects of sacral nerve stimulation: a novel spinal afferent and vagal efferent pathway

Sacral nerve stimulation (SNS) was reported to improve 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. The aim of this study was to investigate whether the SNS anti-inflammatory effect is mediated via the local sacral splanchnic nerve or the spinal afferent-vagal efferent-colon pathway. Under general anesthesia, rats were administrated with TNBS intrarectally, and bipolar SNS electrodes were implanted unilaterally at S₃. The sacral and vagal nerves were severed at different locations for the assessment of the neural pathway. SNS for 10 days improved colonic inflammation only in groups with intact afferent sacral nerve and vagus efferent nerve. SNS markedly increased acetylcholine and anti-inflammatory cytokines (IL-10) and decreased myeloperoxidase and proinflammatory cytokines (IL-2, IL-17A, and TNF-α) in colon tissues. SNS increased the number of c-fos-positive cells in the brain stem and normalized vagal activity measured by spectral analysis of heart rate variability. SNS exerts an anti-inflammatory effect on TNBS-induced colitis by enhancing vagal activity mediated mainly via the spinal afferent-brain stem-vagal efferent-colon pathway.NEW & NOTEWORTHY Our findings support that there is a possible sacral afferent-vagal efferent pathway that can transmit sacral nerve stimulation to the colon tissue. Sacral nerve stimulation can be carried out by spinal cord afferent to the brain stem and then by the vagal nerve (efferent) to the target organ.

Berberine ameliorates non-steroidal anti-inflammatory drugs-induced intestinal injury by the repair of enteric nervous system

The study was to detect the role of GDNF, PGP9.5 (a neuronal marker), and GFAP (EGCs' marker) in the mechanism of non-steroidal anti-inflammatory drugs (NSAIDs) related to intestinal injury and to clarify the protective effect of berberine in the treatment of NSAID-induced small intestinal disease. Forty male SD rats were divided randomly into five groups (A-E): Group A: control group; Group B: model group received diclofenac sodium 7.5 mg/(kg*day) for 5 days; Group C-E: berberine low, medium and high dose groups were treated by 7.5 mg/(kg*day) diclofenac sodium for 5 days then received berberine 25 mg/(kg*day), 50 mg/(kg*day), and 75 mg/(kg*day), respectively, between the sixth and eighth day. Intestinal mucosa was taken on the ninth day to observe the general, histological injuries, and to measure the intestinal epithelial thickness. Then, immunohistochemistry was performed to detect the expression of PGP9.5 and GFAP, and Western blot was performed to detect GDNF expression. The histological score and the general score in the model group were, respectively, 5.75 ± 1.04 and 4.83 ± 0.92. Scores in berberine medium and high berberine group were lower compared with the model group (P < 0.05). The intestinal epithelial thickness in the model group was lower than in the control group and the berberine groups (P < 0.05). PGP9.5, GFAP, and GDNF content in the model group and the three berberine groups were significantly lower than in the control groups (P < 0.05). PGP9.5, GFAP, and GDNF content in the control group and the three berberine groups were higher compared with the model groups (P < 0.05). Berberine can protect the intestinal mucosa of NSAID users, and the mechanism is associated with the reparation of the enteric nervous system via upregulating the expression of PGP9.5, GFAP, and GDNF.

Sacral nerve stimulation improves colonic inflammation mediated by autonomic-inflammatory cytokine mechanism in rats

BACKGROUND

Vagal nerve stimulation (VNS) was reported to have a therapeutic potential for inflammatory bowel disease (IBD). This study was designed to determine effects and mechanisms of SNS on colonic inflammation of in rodent models of IBD and compare the difference among SNS, VNS, and SNS plus VNS.

METHODS

Intestinal inflammation in rats was induced by intrarectal administration of TNBS (2,4,6-Trinitrobenzenesulfonic acid) on the first day. Five days after intrarectal TNBS, the rats were treated with sham-VNS, VNS, Sham-SNS, SNS, and SNS + VNS for 10 days. In another experiment, after 10 days of 4% DSS (dextran sodium sulfate) in drinking water, rats were treated with 10-day sham-SNS and SNS. Various inflammatory responses were assessed; mechanisms involving autonomic functions and inflammatory cytokines were investigated.

KEY RESULTS

(a) VNS, SNS, and VNS + SNS significantly and equally decreased the disease activity index and macroscopic scores, and normalized colon length; (b) IL-10 was decreased by TNBS but increased with SNS, VNS, and SNS + VNS; pro-inflammatory cytokines, IL-6, IL-17A, MCP-1 and TNF-α, were increased by TNBS but decreased with SNS, VNS, and SNS + VNS (P < .05); MPO activity was decreased by SNS, VNS, and SNS + VNS; (c) SNS, VNS, and SNS + VNS remarkably increased vagal activity that was suppressed by TNBS (P < .05); (d) smilar SNS effects were noted in rats with DSS-induced colitis.

CONCLUSIONS & INFERENCES

SNS presents similar anti-inflammatory effects as VNS by inhibiting pro-inflammatory cytokines and increasing anti-inflammatory cytokines via the autonomic pathway. Similar to VNS, SNS may also have a therapeutic potential for colonic inflammation.

Perioperative Transcutaneous Tibial Nerve Stimulation to Reduce Postoperative Ileus After Colorectal Resection: A Pilot Study

BACKGROUND

Postoperative ileus involves an inflammatory pathway characterized by an increase of inflammation mediators in the colon wall; this could probably be prevented by sacral nerve neuromodulation. The posterior tibial nerve can be stimulated electrically to mimic neuromodulation.

OBJECTIVE

The aims of this study were to assess the efficacy of transcutaneous posterior tibial nerve stimulation in reducing the delay in GI motility recovery, to assess the safety of posterior tibial nerve stimulation in a perioperative setting, and to assess the efficacy of posterior tibial nerve stimulation in reducing the occurrence of postoperative ileus.

DESIGN

This was a preliminary randomized controlled study.

SETTINGS

This study was conducted in 1 academic hospital in France.

PATIENTS

Forty patients undergoing an elective colectomy were included and randomly assigned into 2 groups, posterior tibial nerve stimulation or placebo, according to the side of colectomy and the surgical access size.

INTERVENTION

Perioperative posterior tibial nerve stimulation or placebo was performed 3 times per day according to the randomly assigned group.

MAIN OUTCOME MEASURES

Delay in GI motility recovery (passage of stool and tolerance of solid food) was measured.

RESULTS

Of the 40 patients included, 34 were included in the final analysis, in which 2 patients in the placebo group were allocated the incorrect device. The 6 other patients were secondarily excluded because of protocol deviation. In the intention-to-treat analysis, the mean delay in GI motility recovery was 3.6 and 3.11 days (in the placebo and tibial nerve stimulation groups; p = 0.60). Occurrence of postoperative ileus was not significantly higher in the placebo group (35.3% vs 17.6%; p = 0.42). In the per-protocol analysis, we observed the same trends except for the occurrence of postoperative ileus, which was significantly higher in the placebo group (p = 0.045). Tolerance to posterior tibial nerve stimulation was good, and all of the patients completed the protocol.

LIMITATIONS

The amplitude of stimulation is set according to patient sensation, so some patients could have been aware of their group. In addition there were some inherent limitations because of the preliminary nature of the study and several deviations from the protocol.

CONCLUSIONS

Posterior tibial nerve stimulation was safe in a perioperative setting and had a potential effect on GI motility recovery. The results of this study will be useful for sample size calculations in a larger prospective randomized trial. See Video Abstract at http://links.lww.com/DCR/A708.

Development of a CT-guided standard approach for tined lead implantation at the sacral nerve root S3 in minipigs for chronic neuromodulation

PURPOSE

The aim of this study was to develop a controlled approach for sacral neuromodulation (SNM) to improve both nerve targeting and tined lead placement, for which a new computed tomography (CT)-guided implantation technique was analyzed in minipigs.

MATERIALS AND METHODS

This study included five female, adult Göttingen minipigs. In deep sedoanalgesia, the minipigs were placed in an extended prone position. Commercially available SNM materials were used (needle, introduction sheath, and quadripolar tined lead electrode). Gross anatomy was displayed by CT, and the nerves were bilaterally identified. The optimal angles to puncture the S3 foramen, the resulting access path, and the site for the skin incision were defined subsequently. The needle puncture and the tined lead placement were followed by successive CT scans/3D-reconstruction images. Once proper CT-guided placement of the needle and electrode was established, response to functional stimuli was intraoperatively checked to verify correct positioning.

RESULTS

Successful bilateral tined lead implantation was performed in four out of five minipigs. Implantation was different from the clinical situation because the puncture was done from the contralateral side at a 30° angle to the midline and 60° horizontal angle to ensure both passage through the foramen and nerve access. Surgery time was 50-150 minutes. Stimulation response comprised a twitch of the perianal musculature and tail rotation to the contralateral side.

CONCLUSION

We have established a new, minimally invasive, highly standardized, CT-guided SNM electrode implantation technique. Functional outcomes are clearly defined and reproducible. All procedures can be performed without complications. Future chronic stimulation studies in minipigs can thereby be conducted using a controlled and highly standardized protocol.

Sacral nerve stimulation enhances early intestinal mucosal repair following mucosal injury in a pig model

KEY POINTS

Reducing intestinal epithelial barrier (IEB) dysfunctions is recognized as being of major therapeutic interest for various intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability. Here, we report in a pig model that SNS enhances morphological and functional recovery of IEB following mucosal injury induced via 2,4,6-trinitrobenzenesulfonic acid. These effects are associated with an increased expression of tight junction proteins such as ZO-1 and FAK. These results establish that SNS enhances intestinal barrier repair in acute mucosal injury. They further set the scientific basis for future use of SNS as a complementary or alternative therapeutic option for the treatment of gut disorders with IEB dysfunctions such as inflammatory bowel diseases or irritable bowel syndrome.

ABSTRACT

Intestinal epithelial barrier (IEB) dysfunctions, such as increased permeability or altered healing, are central to intestinal disorders. Sacral nerve stimulation (SNS) is known to reduce IEB permeability, but its ability to modulate IEB repair remains unknown. This study aimed to characterize the impact of SNS on mucosal repair following 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced lesions. Six pigs were stimulated by SNS 3 h prior to and 3 h after TNBS enema, while sham animals (n = 8) were not stimulated. The impact of SNS on mucosal changes was evaluated by combining in vivo imaging, histological and functional methods. Biochemical and transcriptomic approaches were used to analyse the IEB and mucosal inflammatory response. We observed that SNS enhanced the recovery from TNBS-induced increase in transcellular permeability. At 24 h, TNBS-induced alterations of mucosal morphology were significantly less in SNS compared with sham animals. SNS reduced TNBS-induced changes in ZO-1 expression and its epithelial pericellular distribution, and also increased pFAK/FAK expression compared with sham. Interestingly, SNS increased the mucosal density of neutrophils, which was correlated with an increase in trypsin and TGF-β1 levels compared with sham. Finally, SNS prevented the TNBS-induced increases in IL-1β and IL-4 over time that were observed with sham treatment. In conclusion, our results show that SNS enhances mucosal repair following injury. This study highlights novel mechanisms of action of SNS and identifies SNS as a new therapy for diseases with IEB repair disorders.

Bilateral compared with unilateral sacral nerve stimulation for faecal incontinence: results of a randomized, single-blinded crossover study

AIM

This randomized single-blinded crossover study aimed to investigate whether bilateral sacral nerve stimulation (SNS) is more efficient than unilateral stimulation for faecal incontinence (FI).

METHOD

Patients with FI who responded during a unilateral test stimulation, with a minimum improvement of 50% were eligible. Twenty-seven patients who were accepted to enter the trial were bilaterally implanted with two permanent leads and pacemakers. Patients were randomized into three periods of 4 weeks' stimulation including unilateral right, unilateral left and bilateral stimulation. Symptoms scores and bowel habit diaries were collected at baseline and in each study period. A 1-week washout was introduced between each study period.

RESULTS

Twenty-seven (25 female) patients with a median age of 63 (36-84) years were bilaterally implanted from May 2009 to June 2012. The median number of episodes of FI per 3 weeks significantly decreased from 17 (3-54) at baseline to 2 (0-20) during stimulation on the right side, 2 (0-42) during stimulation on the left side and 1 (0-25) during bilateral stimulation. The Wexner incontinence score improved significantly from a median of 16 (10-20) at baseline to 9 (0-14) with right-side stimulation, 10 (0-15) with left-side stimulation and 9 (0-14) with bilateral stimulation. The differences between unilateral right or unilateral left and bilateral stimulation were non-significant, for FI episodes (P = 0.3) or for Wexner incontinence score (P = 0.9).

CONCLUSION

Bilateral SNS therapy for FI is not superior to standard unilateral stimulation in the short term. Equal functional results can be obtained regardless of the side of implantation.

Effects of 1-week sacral nerve stimulation on the rectal intestinal epithelial barrier and neuromuscular transmission in a porcine model

BACKGROUND

Sacral nerve stimulation (SNS) is a validated treatment for fecal incontinence, although the mechanism of action remains unknown. Short-term effects of SNS on the intestinal epithelial barrier (IEB) have been reported previously. The aim of our study was to assess the impact of a 1-week SNS on the IEB in a preclinical model.

METHODS

Fourteen pigs were implanted for bilateral SNS. Seven pigs received 7-day stimulation, whereas the remaining animals received no stimulation. Rectal biopsies were performed before and after SNS. We assessed IEB permeability, mucosal tight junction and cytokine mRNA expression, IL-6 production in an organotypic culture model, and neuromuscular transmission in muscle strips.

KEY RESULTS

IEB permeability was not modified after stimulation, as compared with baseline. The PAR-induced increase in IEB permeability and the mucosal ZO-1 mRNA decrease observed in the controls were not observed into the stimulated group. Cytokine overexpression was not observed in the mucosa in either group. SNS decreased IL-6 production in the organotypic culture model. In the stimulated group, the area-under-the-curve of the EFS-induced contractile response was significantly increased.

CONCLUSIONS & INFERENCES

The main conclusions of our work are (i) the successful development of a preclinical model of bilateral SNS and (ii) in physiological conditions, 1-week SNS did not lead to functional changes in the mucosa. While under stress-induced conditions, SNS modified the properties of the IEB, leading to a decrease in its permeability. Neuromuscular transmission was modified by SNS, leading to neuronal hyperexcitability. These results add evidence to the reinforcement of the IEB by SNS.

A systematic review of sacral nerve stimulation mechanisms in the treatment of fecal incontinence and constipation

BACKGROUND

Sacral nerve stimulation (SNS) is now well established as a treatment for fecal incontinence (FI) resistant to conservative measures and may also have utility in the management of chronic constipation; however, mechanism of action is not fully understood. End organ effects of SNS have been studied in both clinical and experimental settings, but interpretation is difficult due to the multitude of techniques used and heterogeneity of reported findings. The aim of this study was to systematically review available evidence on the mechanisms of SNS in the treatment of FI and constipation.

METHODS

Two systematic reviews of the literature (performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses framework) were performed to identify manuscripts pertaining to (a) clinical and (b) physiological effects of SNS during the management of hindgut dysfunction.

KEY RESULTS

The clinical literature search revealed 161 articles, of which 53 were deemed suitable for analysis. The experimental literature search revealed 43 articles, of which nine were deemed suitable for analysis. These studies reported results of investigative techniques examining changes in cortical, gastrointestinal, colonic, rectal, and anal function.

CONCLUSIONS & INFERENCES

The initial hypothesis that the mechanism of SNS was primarily peripheral motor neurostimulation is not supported by the majority of recent studies. Due to the large body of evidence demonstrating effects outside of the anorectum, it appears likely that the influence of SNS on anorectal function occurs at a pelvic afferent or central level.

Role of enteric neurotransmission in host defense and protection of the gastrointestinal tract

Host defense is a vital role played by the gastrointestinal tract. As host to an enormous and diverse microbiome, the gut has evolved an elaborate array of chemical and physicals barriers that allow the digestion and absorption of nutrients without compromising the mammalian host. The control of such barrier functions requires the integration of neural, humoral, paracrine and immune signaling, involving redundant and overlapping mechanisms to ensure, under most circumstances, the integrity of the gastrointestinal epithelial barrier. Here we focus on selected recent developments in the autonomic neural control of host defense functions used in the protection of the gut from luminal agents, and discuss how the microbiota may potentially play a role in enteric neurotransmission. Key recent findings include: the important role played by subepithelial enteric glia in modulating intestinal barrier function, identification of stress-induced mechanisms evoking barrier breakdown, neural regulation of epithelial cell proliferation, the role of afferent and efferent vagal pathways in regulating barrier function, direct evidence for bacterial communication to the enteric nervous system, and microbial sources of enteric neurotransmitters. We discuss these new and interesting developments in our understanding of the role of the autonomic nervous system in gastrointestinal host defense.

The digestive neuronal-glial-epithelial unit: a new actor in gut health and disease

The monolayer of columnar epithelial cells lining the gastrointestinal tract--the intestinal epithelial barrier (IEB)--is the largest exchange surface between the body and the external environment. The permeability of the IEB has a central role in the regulation of fluid and nutrient intake as well as in the control of the passage of pathogens. The functions of the IEB are highly regulated by luminal as well as internal components, such as bacteria or immune cells, respectively. Evidence indicates that two cell types of the enteric nervous system (ENS), namely enteric neurons and enteric glial cells, are potent modulators of IEB functions, giving rise to the novel concept of a digestive 'neuronal-glial-epithelial unit' akin to the neuronal-glial-endothelial unit in the brain. In this Review, we summarize findings demonstrating that the ENS is a key regulator of IEB function and is actively involved in pathologies associated with altered barrier function.