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

Abstract

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 β-adrenergic receptors (β-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 β-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.

Voltammetry in the spleen assesses real-time anti-inflammatory norepinephrine release elicited by autonomic neurostimulation

“…Previous studies of LPS endotoxemia report considerable variability in TNF inhibition in response to VNS or SpNS [12,35,54]. Accordingly, we found that the same intensity of SpNS produces a wide range of TNF responses in animals injected with LPS (Fig.…”

“…4C). In a study by Brinkman et al [12], most of the animals receiving splenic nerve stimulation had TNF values close to those of the sham-stimulated group (~ 6000 pg/mL vs. ~7500 pg/mL, respectively). The results from our study, which used similar stimulation parameters, suggest that in the Brinkman et al study it is likely that in a subset of animals that showed smaller TNF suppression, Q o may have been similarly high.…”

“…The innervation of the spleen by the autonomic nervous system is implicated in the neural control of in ammation [1][2][3]. Both spinal sympathetic and vagal preganglionic neurons interact with the splenic nerve, and their stimulation results in increased splenic nerve activity and suppression of in ammation [4][5][6][7][8][9][10][11][12]. Part of this anti-in ammatory effect is initiated by the release of norepinephrine (NE) in the spleen parenchyma by terminals of the splenic nerve, followed by the release of acetylcholine by specialized Tcells and suppression of pro-in ammatory cytokine production by splenic macrophages.…”

“…These ndings prompted the development of new treatments for in ammatory diseases using neurostimulation devices to modulate the activity of autonomic nerves under the umbrella of the growing eld of Bioelectronic Medicine [13]. Therapies involving cervical vagus nerve stimulation (VNS) [14], trans-auricular VNS [15,16], splenic nerve stimulation [8], and ultrasound stimulation of the spleen [5,6] all rely on the autonomic innervation of the spleen as the common nal target to suppress in ammation in patients with in ammatory diseases [5,6,9,11,12].…”

Autonomic nerves differentially control inflammation during endotoxaemia

“…For instance, splenectomy greatly reduces the early increases in plasma TNF‐α induced by endotoxaemia. Splenic nerve stimulation suppresses the release of TNF‐α in an animal model of inflammatory bowel disease (Brinkman et al., 2022). However, even though splenic nerve activity is elevated during endotoxaemia (Martelli et al., 2014), denervation of the spleen does not change TNF‐α or IL‐10 levels in the bloodstream (McKinley et al., 2022).…”