Sympathetic activity regulates epithelial proliferation and wound healing via adrenergic receptor α2A.

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.

Sympathetic Innervation Modulates Mucosal Immune Homeostasis and Epithelial Host Defense.

Intestinal mucosal cells, such as resident macrophages and epithelial cells, express adrenergic receptors and are receptive to norepinephrine, the primary neurotransmitter of the sympathetic nervous system (SNS). It has been suggested that the SNS affects intestinal immune activity in conditions, such as inflammatory bowel disease; however, the underlying mechanisms remain ambiguous. Here, we investigated the effect of SNS on mucosal immune and epithelial cell functions. We employed 6-OHDA-induced sympathetic denervation (cSTX) to characterize muscularis-free mucosal transcriptomes by RNA-seq and qPCR, and quantified mucosal immune cells by flow cytometry. The role of norepinephrine and cytokines on epithelial functions was studied using small intestinal organoids. cSTX increased the presence of activated CD68+CD86+ macrophages and monocytes in the mucosa. In addition, through transcriptional profiling, the proinflammatory cytokines IL-1ß, TNF-α, and IFN-γ were induced, while Arg-1 and CD163 expression was reduced. Further, cSTX increased intestinal permeability in vivo and induced genes involved in barrier integrity and antimicrobial defense. In intestinal organoids, similar alterations were observed after treatment with proinflammatory cytokines, but not norepinephrine. We conclude that a loss in sympathetic input induces a proinflammatory mucosal state, leading to reduced epithelial barrier functioning and enhanced antimicrobial defense. This implies that the SNS might be required to maintain intestinal immune functions during homeostasis.

Electrical stimulation of the splenic nerve bundle ameliorates dextran sulfate sodium-induced colitis in mice.

BACKGROUND: Vagus nerve stimulation has been suggested to affect immune responses, partly through a neuronal circuit requiring sympathetic innervation of the splenic nerve bundle and norepinephrine (NE) release. Molecular and cellular mechanisms of action remain elusive. Here, we investigated the therapeutic value of this neuromodulation in inflammatory bowel disease (IBD) by applying electrical splenic nerve bundle stimulation (SpNS) in mice with dextran sulfate sodium (DSS)-induced colitis. METHODS: Cuff electrodes were implanted around the splenic nerve bundle in mice, whereupon mice received SpNS or sham stimulation. Stimulation was applied 6 times daily for 12 days during DSS-induced colitis. Colonic and splenic tissues were collected for transcriptional analyses by qPCR and RNA-sequencing (RNA-seq). In addition, murine and human splenocytes were stimulated with lipopolysaccharide (LPS) in the absence or presence of NE. Single-cell RNA-seq data from publicly available data sets were analyzed for expression of ß-adrenergic receptors (ß-ARs). RESULTS: Colitic mice undergoing SpNS displayed reduced colon weight/length ratios and showed improved Disease Activity Index scores with reduced Tumor Necrosis Factor α mRNA expression in the colon compared with sham stimulated mice. Analyses of splenocytes from SpNS mice using RNA-seq demonstrated specific immune metabolism transcriptome profile changes in myeloid cells. Splenocytes showed expression of ß-ARs in myeloid and T cells. Cytokine production was reduced by NE in mouse and human LPS-stimulated splenocytes. CONCLUSIONS: Together, our results demonstrate that SpNS reduces clinical features of colonic inflammation in mice with DSS-induced colitis possibly by inhibiting splenic myeloid cell activation. Our data further support exploration of the clinical use of SpNS for patients with IBD.

Neuronal innervation of the intestinal crypt.

Mucosal damage is a key feature of inflammatory bowel diseases (IBD) and healing of the mucosa is an endpoint of IBD treatment that is often difficult to achieve. Autonomic neurons of the parasympathetic and sympathetic nervous system may influence intestinal epithelial cell growth and modulating epithelial innervation could for that reason serve as an interesting therapeutic option to improve mucosal healing. Understanding of the biological processes triggered by nonspecific and specific epithelial adrenergic and cholinergic receptor activation is of key importance. At present, with rising technological advances, bioelectronic neuromodulation as treatment modality has gained momentum. We discuss the current view on state-of-the-art innervation of the intestinal crypt and its impact on epithelial cell growth and differentiation. Furthermore, we outline bioelectronic technology and review its relevance to wound healing processes.

Treatment of symptomatic postoperative pelvic lymphoceles: A systematic review.

PURPOSE: A broad range of therapeutic options exists for symptomatic postoperative lymphoceles. However, no consensus exists on what is the optimal therapy. In this study, we aimed to compare the efficacy of currently available radiologic interventions in terms of number of successful interventions, number of recurrences, and number of complications. METHODS: A systematic review was conducted with a pre-defined search strategy for PubMed, EMBASE, and Cochrane databases from inception until September 2019. Quality assessment was performed using the 'Risk Of Bias In Non-randomized Studies - of Interventions' tool. Statistical heterogeneity was assessed using the I2 and χ2 test and a meta-analysis was considered for studies reporting on multiple interventions. RESULTS: 37 eligible studies including 732 lymphoceles were identified. Proportions of successful interventions for percutaneous fine needle aspiration, percutaneous catheter drainage, percutaneous catheter drainage with delayed or instantaneous addition of sclerotherapy, and embolization were as follows: 0.341 (95% confidence interval [CI]: 0.185-0.542), 0.612 (95% CI: 0.490-0.722), 0.890 (95% CI: 0.781-0.948), 0.872 (95% CI: 0.710-0.949), 0.922 (95% CI: 0.731-0.981). Random-effects meta-analysis of seven studies revealed a pooled relative risk for percutaneous catheter drainage with delayed addition of sclerotherapy of 1.57 (95% CI: 1.17-2.10) when compared to percutaneous catheter drainage alone. The risk of bias in this study was severe. CONCLUSIONS: This systematic review demonstrates that the success rates of percutaneous catheter drainage with sclerotherapy are more favorable when compared to percutaneous catheter drainage alone in the treatment of postoperative pelvic lymphoceles. Overall, percutaneous catheter drainage with delayed addition of sclerotherapy, and embolization showed the best outcomes.

The role of nicotinic receptors in SARS-CoV-2 receptor ACE2 expression in intestinal epithelia.

BACKGROUND: Recent evidence demonstrated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) propagates in intestinal epithelial cells expressing Angiotensin-Converting Enzyme 2 (ACE2), implying that these cells represent an important entry site for the viral infection. Nicotinic receptors (nAChRs) have been put forward as potential regulators of inflammation and of ACE2 expression. As vagus nerve stimulation (VNS) activates nAChRs, we aimed to investigate whether VNS can be instrumental in affecting intestinal epithelial ACE2 expression. METHODS: By using publicly available datasets we qualified epithelial ACE2 expression in human intestine, and assessed gene co-expression of ACE2 and SARS-CoV-2 priming Transmembrane Serine Protease 2 (TMPRSS2) with nAChRs in intestinal epithelial cells. Next, we investigated mouse and human ACE2 expression in intestinal tissues after chronic VNS via implanted devices. RESULTS: We show co-expression of ACE2 and TMPRSS2 with nAChRs and α7 nAChR in particular in intestinal stem cells, goblet cells, and enterocytes. However, VNS did not affect ACE2 expression in murine or human intestinal tissue, albeit in colitis setting. CONCLUSIONS: ACE2 and TMPRSS2 are specifically expressed in epithelial cells of human intestine, and both are co-expressed with nAChRs. However, no evidence for regulation of ACE2 expression through VNS could be found. Hence, a therapeutic value of VNS with respect to SARS-CoV-2 infection risk through ACE2 receptor modulation in intestinal epithelia could not be established.

Neuroimmune Interactions in the Gut and Their Significance for Intestinal Immunity.

Inflammatory bowel diseases (IBD) have a complex, multifactorial pathophysiology with an unmet need for effective treatment. This calls for novel strategies to improve disease outcome and quality of life for patients. Increasing evidence suggests that autonomic nerves and neurotransmitters, as well as neuropeptides, modulate the intestinal immune system, and thereby regulate the intestinal inflammatory processes. Although the autonomic nervous system is classically divided in a sympathetic and parasympathetic branch, both play a pivotal role in the crosstalk with the immune system, with the enteric nervous system acting as a potential interface. Pilot clinical trials that employ vagus nerve stimulation to reduce inflammation are met with promising results. In this paper, we review current knowledge on the innervation of the gut, the potential of cholinergic and adrenergic systems to modulate intestinal immunity, and comment on ongoing developments in clinical trials.

Similar Short- and Long-term Colectomy Rates with Ciclosporin and Infliximab Treatment in Hospitalised Ulcerative Colitis Patients.

BACKGROUND AND AIMS: Ciclosporin A [CsA] and infliximab [IFX] are similarly effective in preventing short-term colectomy in ulcerative colitis [UC] patients, but long-term data are scarce. We aimed to compare short- and long-term efficacy of CsA and IFX by analysing colectomy rates and failure of remission-induction treatment as outcome parameters for treatment success. METHODS: We retrospectively studied hospitalised UC patients who received CsA or IFX for moderate-to-severe UC, between January 2000 and April 2014. The primary endpoint was time to colectomy, and treatment failure [defined as colectomy or another remission-induction treatment with corticosteroids, CsA, or IFX] was used as secondary endpoint. Variables possibly affecting colectomy outcomes were analysed. RESULTS: A total of 55 patients were studied for colectomy outcome and 58 patients for treatment failure. A significantly longer follow-up duration was available for CsA-treated patients [p < 0.001, both subcohorts]. Patients showed comparable patient- and disease-specific characteristics. Colectomy rates did not differ significantly at 3, 12, and 36 months: 36% versus 29%, 58% versus 48%, and 64% versus 67% for CsA- and IFX-treated patients, respectively. Multivariate Cox regression analysis revealed the lowest hazard ratio [HR] for colectomy in patients concomitantly using thiopurines: HR 0.28 (confidence interval [CI] 0.13-0.64), p = 0.002. Treatment failure rates were not significantly different at 3, 12 and 36 months: 35% versus 48%, 51% versus 68%, and 62% versus 83% for CsA- and IFX-treated patients, respectively. CONCLUSIONS: Treatment with CsA and IFX is similarly effective in preventing short- and long-term colectomy in hospitalised UC patients. Furthermore, failure rates of these remission-induction treatments were comparable.