Noninvasive ultrasound stimulation of the spleen to treat inflammatory arthritis

Exploring the Potential Role of the Cholinergic Anti-Inflammatory Pathway from the Perspective of Sepsis Pathophysiology

Sepsis is one of the most prevalent conditions in critical care medicine and is characterized by a high incidence, mortality, and poor prognosis, with no specific treatment currently available. The pathogenesis of sepsis is complex with a dysregulated inflammatory response at its core. If the initial inflammatory response is not promptly controlled, patients often develop multiple organ dysfunction syndrome or die, whereas survivors may experience post-sepsis syndrome. Regulation by the central and autonomic nervous systems is essential for maintaining inflammatory homeostasis. Among these, the cholinergic anti-inflammatory pathway (CAP) has been extensively studied in sepsis owing to its significant role in modulating inflammatory responses. Recent advancements in CAP-related interventions include minimally invasive vagus nerve stimulation, novel α7nAchR-targeting drugs, serum choline acetyltransferase and cholinesterase, acupuncture, and focused ultrasound stimulation therapy. This review primarily discusses the advantages, limitations, and therapeutic prospects of these approaches. Additionally, heart rate variability, which reflects changes in autonomic nervous system function, can serve as an indicator for assessing the functional status of the vagus nerve. In summary, modulation of inflammatory responses through the vagus nerve-mediated CAP represents a potential strategy for achieving precision medicine for sepsis. Future research should focus on conducting high-quality clinical studies on CAP-based therapies in the context of sepsis-induced inflammatory dysregulation. Incorporating indicators to evaluate the autonomic nervous system function may further elucidate the impact of inflammatory dysregulation in the body.

Low intensity trans-spinal focused ultrasound reduces mechanical sensitivity and suppresses spinal microglia activation in rats with chronic constriction injury

Low intensity, trans-spinal focused ultrasound (tsFUS) is a noninvasive neuromodulation approach that has been shown to modulate spinal circuit excitability in healthy rats. Here, we evaluated the potential of tsFUS for alleviating neuropathic pain by testing it in a chronic constriction injury (CCI) model. Male rats underwent CCI of the left sciatic nerve and then received tsFUS (2 kHz pulse repetition frequency; 40% duty cycle) or sham stimulation, targeted at spinal segment level L5 for 3 min daily over three days. As expected, CCI causes significant reduction of von Frey Threshold (vFT), a measure of mechanical sensitivity. We found that tsFUS treatment is associated with increased vFT compared to sham; this increase persists beyond the duration of treatment, through days 4 to 23 post-CCI. In spinal cords of tsFUS-treated animals, counts of spinal microglia (Iba1 + cells) and of activated, pro-inflammatory microglia (Iba1 + /CD86 + cells), are reduced compared to sham-treated animals. This reduction in microglia counts is limited to the insonified side of the spinal cord, ipsilateral to CCI. These findings suggest that tsFUS may be a promising approach for treatment of neuropathic pain at early stages, possibly by attenuating the development of microglial-driven inflammation.

Targeted spleen modulation: a novel strategy for next-generation disease immunotherapy

The spleen, the largest lymphatic organ, comprises a diverse array of immunocytes in approximately one quarter of the body, including T cells, B cells, natural killer cells, and myeloid cells (such as dendritic cells, neutrophils, myeloid-derived suppressor cells, and macrophages). These immune cells undergo dynamic transitions and mobilization, enabling the spleen to execute a wide range of immunological functions. The spleen's structural organization and multicellular composition, along with its reservoir of lymphocytes, facilitate the capture and clearance of blood-borne antigens while also orchestrating both innate and adaptive immune responses. Additionally, the spleen plays critical roles in hematopoiesis and the removal of aged or damaged red blood cells. Despite being innervated by sympathetic (catecholaminergic) nerve fibers, the spleen lacks parasympathetic (vagal or cholinergic) innervation. The neuroimmune axis, particularly the interplay between sympathetic and parasympathetic nervous system immune circuits, significantly influences disease onset and progression. Extensive research employing physical, genetic, and pharmacological approaches has sought to directly modulate splenic immunocytes and activate neuroimmune interactions to restore immune homeostasis and counteract disease. Two primary mechanisms underlie these immunomodulatory interventions: (1) the cholinergic anti-inflammatory pathway, wherein norepinephrine released by splenic catecholaminergic fibers binds to β2-adrenergic receptors on CD4⁺ T cells, triggering acetylcholine secretion, which in turn suppresses inflammatory cytokine production in macrophages via α7 nicotinic acetylcholine receptor signaling, and (2) direct immunomodulation of splenic immunocytes, which regulates key genes and signaling pathways, alters cytokine secretion, and modulates ion flux to influence cellular functions. Among various therapeutic strategies, physical methods, particularly electrical stimulation and splenic ultrasound stimulation, have demonstrated the greatest promise for clinical applications in splenic immunomodulation and disease management.

Noninvasive Vagus Nerve Electrical Stimulation for Immune Modulation in Sepsis Therapy

Sepsis presents a significant medical challenge due to its intense inflammatory response to infection, often resulting in high mortality rates. A promising therapeutic strategy targets the cholinergic anti-inflammatory pathway (CAIP), which regulates immune responses. This study investigates the ingestion of piezoelectric particles that adhere to the stomach lining, specifically targeting TRPV1 receptors. In a mouse model of sepsis, these particles, when activated by low-intensity pulsed ultrasound, generate mild electrical pulses. These pulses stimulate vagal afferent fibers, transmitting signals to the brain and modulating the neural-immune network via the CAIP. Consequently, this leads to a reduction in systemic inflammation, mitigating weight loss, alleviating multiple tissue injuries, and preventing death by modulating immune cells in the spleen. This approach addresses the critical need for noninvasive sepsis therapies, potentially improving patient outcomes. Utilizing portable ultrasound equipment with minimal thermal effects, this technique offers a safe and convenient treatment option, even for home use.

Single-cell RNA sequencing in autoimmune diseases: New insights and challenges

Autoimmune diseases involve a variety of cell types, yet the intricacies of their individual roles within molecular mechanisms and therapeutic strategies remain poorly understood. Single-cell RNA sequencing (scRNA-seq) offers detailed insights into transcriptional diversity at the single-cell level, significantly advancing research in autoimmune diseases. This article explores how scRNA-seq enhances the understanding of cellular heterogeneity and its potential applications in the etiology, diagnosis, treatment, and prognosis of autoimmune diseases. By revealing a comprehensive cellular landscape, scRNA-seq illuminates the functional regulation of different cell subtypes during disease progression. It aids in identifying diagnostic and prognostic markers, and analyzing cell communication networks to uncover potential therapeutic targets. Despite its valuable contributions, addressing the limitations of scRNA-seq is essential for making further advancements.

Subcellular Cavitation Bubbles Induce Cellular Mechanolysis and Collective Wound Healing in Ultrasound-Inflicted Cell Ablation

Focused ultrasound (FUS) has been widely adopted in medical and life science researches. Although various physical and biological effects of FUS have been well-documented, there is still a lack of understanding and direct evidence on the biological mechanism of therapeutic cell ablation caused by high-intensity ultrasound (HIFU) and the subsequent wound healing responses. This study develops an enclosed cell culture device that synergistically combines non-invasive FUS stimulation and real-time, on-the-fly live-cell imaging, providing an in vitro platform to explore short and long-term biological effects of ultrasound. The process, mechanism, and wound healing response of cell ablation induced by HIFU are elucidated, revealing a unique mechanism, termed ultrasound-inflicted cellular mechanolysis, that is mediated by growing subcellular cavitation air bubbles under confined contact with cells. This provides a previously unappreciated mechanism for understanding the biomechanical principles of ultrasound-based ablative therapy. A post-ablation phantom layer is also revealed that serves as a guiding cue for collective cell migration during wound healing, thereby providing a biomimetic model for studying wound healing after HIFU-inflicted damage. Together, this study provides theoretical and technological basis for advancing the understanding of the biological effects of ultrasound-based ablative therapy and inspiring clinically relevant applications in the future.

Revolutionizing an Imaging Technology for Groundbreaking Treatment

Noninvasive ultrasound devices are in development to treat dementia, arthritis, chronic pain and other health conditions.

Next generation bioelectronic medicine: making the case for non-invasive closed-loop autonomic neuromodulation

The field of bioelectronic medicine has advanced rapidly from rudimentary electrical therapies to cutting-edge closed-loop systems that integrate real-time physiological monitoring with adaptive neuromodulation. Early innovations, such as cardiac pacemakers and deep brain stimulation, paved the way for these sophisticated technologies. This review traces the historical and technological progression of bioelectronic medicine, culminating in the emerging potential of closed-loop devices for multiple disorders of the brain and body. We emphasize both invasive techniques, such as implantable devices for brain, spinal cord and autonomic regulation, while we introduce new prospects for non-invasive neuromodulation, including focused ultrasound and newly developed autonomic neurography enabling precise detection and titration of inflammatory immune responses. The case for closed-loop non-invasive autonomic neuromodulation (incorporating autonomic neurography and splenic focused ultrasound stimulation) is presented through its applications in conditions such as sepsis and chronic inflammation, illustrating its capacity to revolutionize personalized healthcare. Today, invasive or non-invasive closed-loop systems have yet to be developed that dynamically modulate autonomic nervous system function by responding to real-time physiological and molecular signals; it represents a transformative approach to therapeutic interventions and major opportunity by which the bioelectronic field may advance. Knowledge gaps remain and likely contribute to the lack of available closed loop autonomic neuromodulation systems, namely, (1) significant exogenous and endogenous noise that must be filtered out, (2) potential drift in the signal due to temporal change in disease severity and/or therapy induced neuroplasticity, and (3) confounding effects of exogenous therapies (e.g., concurrent medications that dysregulate autonomic nervous system functions). Leveraging continuous feedback and real-time adjustments may overcome many of these barriers, and these next generation systems have the potential to stand at the forefront of precision medicine, offering new avenues for individualized and adaptive treatment.

Extremely low-frequency electromagnetic fields targeting spleen modifies the populations of immunocytes in the spleen

Our study focused on investigating the bioeffects of extremely low-frequency electromagnetic fields (ELF-EMFs) on the immune function of the spleen. We designed an electromagnetic instrument that can locally target on spleen, the spleens of mice were locally exposed to the ELF-EMF (50 Hz, 30 mT) for 14 days (4 h/day). Parallelly, the isolated splenic T cells were exposed to ELF-EMF (50 Hz, 15 mT) for 2 h. After the exposure, the splenocyte showed a reduced apoptosis rate. Among the splenocytes, the CD4+ T cells and natural killer cells accumulated, the percentage of B cells decreased. In vitro study demonstrated that ELF-EMF induced the alteration of T cell subsets, showing an increased percentage of CD4+ T cells and a decreased percentage of CD8+ T cells. Within CD4+ T cells, the population of T helper (Th) 17 cells increased, and the population of regulatory T cells (Treg) cells decreased. The enrichment of the nuclear factor (NF)-κB pathway in the splenic T cells was found to be reduced after exposure to ELF-EMF. Our findings suggest that ELF-EMF regulated the immune function of the spleen by changing the proportion of immune cells in the spleen. Specifically, the differentiation of spleen T cells was induced by ELF-EMF toward Th17 cells and inhibited by ELF-EMF into Treg cells. The NF-κB signaling pathway probably accounts for the effects of ELF-EMF on the spleen T cells.

Medical Ultrasound Application Beyond Diagnosis: Insights From Ultrasound Sensing and Biological Response

Ultrasound (US) can easily penetrate media with excellent spatial precision corresponding to its wavelength. Naturally, US plays a pivotal role in the echolocation abilities of certain mammals such as bats and dolphins. In addition, medical US generated by transducers interact with tissues via delivering ultrasonic energy in the modes of heat generation, exertion of acoustic radiation force (ARF), and acoustic cavitation. Based on the principle of echolocation, various assistive devices for visual impairment people have been developed. High-Intensity Focused Ultrasound (HIFU) are developed for targeted ablation and tissue destruction. Besides thermal ablation, histotripsy with US is designed to damage tissue purely via mechanical effect without thermal coagulation. Low-Intensity Focused Ultrasound (LIFU) has been proven to be an effective stimulation method for neuromodulation. Furthermore, US has been reported to transiently increase the permeability of biological membranes, enabling acoustic transfection and blood-brain barrier open. All of these advances in US are changing the clinic. This review mainly introduces the advances in these aspects, focusing on the physical and biological principles, challenges, and future direction.

Noninvasive closed-loop acoustic brain-computer interface for seizure control

Rationale: The brain-computer interface (BCI) is core tasks in comprehensively understanding the brain, and is one of the most significant challenges in neuroscience. The development of novel non-invasive neuromodulation technique will drive major innovations and breakthroughs in the field of BCI. Methods: We develop a new noninvasive closed-loop acoustic brain-computer interface (aBCI) for decoding the seizure onset based on the electroencephalography and triggering ultrasound stimulation of the vagus nerve to terminate seizures. Firstly, we create the aBCI system and decode the onset of seizure via a multi-level threshold model based on the analysis of wireless-collected electroencephalogram (EEG) signals recorded from above the hippocampus. Then, the different acoustic parameters induced acoustic radiation force were used to stimulate the vagus nerve in a rat model of epilepsy-induced by pentylenetetrazole. Finally, the results of epileptic EEG signal triggering ultrasound stimulation of the vagus nerve to control seizures. In addition, the mechanism of aBCI control seizures were investigated by real-time quantitative polymerase chain reaction (RT-qPCR). Results: In a rat model of epilepsy, the aBCI system selectively actives mechanosensitive neurons in the nodose ganglion while suppressing neuronal excitability in the hippocampus and amygdala, and stops seizures rapidly upon ultrasound stimulation of the vagus nerve. Physical transection or chemical blockade of the vagus nerve pathway abolish the antiepileptic effects of aBCI. In addition, aBCI shows significant antiepileptic effects compared to conventional vagus nerve electrical stimulation in an acute experiment. Conclusions: Closed-loop aBCI provides a novel, safe and effective tool for on-demand stimulation to treat abnormal neuronal discharges, opening the door to next generation non-invasive BCI.

Low-Intensity Pulsed Ultrasound: A Physical Stimulus with Immunomodulatory and Anti-inflammatory Potential

Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.

Neuroimmune modulation in liver pathophysiology

The liver, the largest organ in the human body, plays a multifaceted role in digestion, coagulation, synthesis, metabolism, detoxification, and immune defense. Changes in liver function often coincide with disruptions in both the central and peripheral nervous systems. The intricate interplay between the nervous and immune systems is vital for maintaining tissue balance and combating diseases. Signaling molecules and pathways, including cytokines, inflammatory mediators, neuropeptides, neurotransmitters, chemoreceptors, and neural pathways, facilitate this complex communication. They establish feedback loops among diverse immune cell populations and the central, peripheral, sympathetic, parasympathetic, and enteric nervous systems within the liver. In this concise review, we provide an overview of the structural and compositional aspects of the hepatic neural and immune systems. We further explore the molecular mechanisms and pathways that govern neuroimmune communication, highlighting their significance in liver pathology. Finally, we summarize the current clinical implications of therapeutic approaches targeting neuroimmune interactions and present prospects for future research in this area.

Lymphoid organ-targeted nanomaterials for immunomodulation of cancer, inflammation, and beyond

Nanomaterials exhibit significant potential for stimulating immune responses, offering both local and systemic modulation across a variety of diseases. The lymphoid organs, such as the spleen and lymph nodes, are home to various immune cells, including monocytes and dendritic cells, which contribute to both the progression and prevention/treatment of diseases. Consequently, many nanomaterial formulations are being rationally designed to target these organs and engage with specific cell types, thereby inducing therapeutic and protective effects. In this review, we explore crucial cellular interactions and processes involved in immune regulation and highlight innovative nano-based immunomodulatory approaches. We outline essential considerations in nanomaterial design with an emphasis on their impact on biological interactions, targeting capabilities, and treatment efficacy. Through selected examples, we illustrate the strategic targeting of therapeutically active nanomaterials to lymphoid organs and the subsequent immunomodulation for infection resistance, inflammation suppression, self-antigen tolerance, and cancer immunotherapy. Additionally, we address current challenges, discuss emerging topics, and share our outlook on future developments in the field.

The emergence of cancer sono-immunotherapy

Owing to its remarkable ease of use, ultrasound has recently been explored for stimulating or amplifying immune responses during cancer therapy, termed 'sono-immunotherapy'. Ultrasound can cause immunogenic cell death in cancer cells via thermal and nonthermal effects to regulate the tumor microenvironment, thereby priming anticancer immunity; by integrating well-designed biomaterials, novel sono-immunotherapy approaches with augmented efficacy can also be developed. Here, we review the advances in sono-immunotherapy for cancer treatment and summarize existing limitations along with potential trends. We offer emerging insights into this realm, which might prompt breakthroughs and expand its potential applications to other diseases.

Ultrasound Neuromodulation of an Anti-Inflammatory Pathway at the Spleen Improves Experimental Pulmonary Hypertension

BACKGROUND

Inflammation is pathogenically implicated in pulmonary arterial hypertension; however, it has not been adequately targeted therapeutically. We investigated whether neuromodulation of an anti-inflammatory neuroimmune pathway involving the splenic nerve using noninvasive, focused ultrasound stimulation of the spleen (sFUS) can improve experimental pulmonary hypertension.

METHODS

Pulmonary hypertension was induced in rats either by Sugen 5416 (20 mg/kg SQ) injection, followed by 21 (or 35) days of hypoxia (sugen/hypoxia model), or by monocrotaline (60 mg/kg IP) injection (monocrotaline model). Animals were randomized to receive either 12-minute-long sessions of sFUS daily or sham stimulation for 14 days. Catheterizations, echocardiography, indices of autonomic function, lung and heart histology and immunohistochemistry, spleen flow cytometry, and lung single-cell RNA sequencing were performed after treatment to assess the effects of sFUS.

RESULTS

Splenic denervation right before induction of pulmonary hypertension results in a more severe disease phenotype. In both sugen/hypoxia and monocrotaline models, sFUS treatment reduces right ventricular systolic pressure by 25% to 30% compared with sham treatment, without affecting systemic pressure, and improves right ventricular function and autonomic indices. sFUS reduces wall thickness, apoptosis, and proliferation in small pulmonary arterioles, suppresses CD3+ and CD68+ cell infiltration in lungs and right ventricular fibrosis and hypertrophy and lowers BNP (brain natriuretic peptide). Beneficial effects persist for weeks after sFUS discontinuation and are more robust with early and longer treatment. Splenic denervation abolishes sFUS therapeutic benefits. sFUS partially normalizes CD68+ and CD8+ T-cell counts in the spleen and downregulates several inflammatory genes and pathways in nonclassical and classical monocytes and macrophages in the lung. Differentially expressed genes in those cell types are significantly enriched for human pulmonary arterial hypertension-associated genes.

CONCLUSIONS

sFUS causes dose-dependent, sustained improvement of hemodynamic, autonomic, laboratory, and pathological manifestations in 2 models of experimental pulmonary hypertension. Mechanistically, sFUS normalizes immune cell populations in the spleen and downregulates inflammatory genes and pathways in the lung, many of which are relevant in human disease.

Disrupted autonomic pathways in spinal cord injury: Implications for the immune regulation

Spinal Cord Injury (SCI) disrupts critical autonomic pathways responsible for the regulation of the immune function. Consequently, individuals with SCI often exhibit a spectrum of immune dysfunctions ranging from the development of damaging pro-inflammatory responses to severe immunosuppression. Thus, it is imperative to gain a more comprehensive understanding of the extent and mechanisms through which SCI-induced autonomic dysfunction influences the immune response. In this review, we provide an overview of the anatomical organization and physiology of the autonomic nervous system (ANS), elucidating how SCI impacts its function, with a particular focus on lymphoid organs and immune activity. We highlight recent advances in understanding how intraspinal plasticity that follows SCI may contribute to aberrant autonomic activity in lymphoid organs. Additionally, we discuss how sympathetic mediators released by these neuron terminals affect immune cell function. Finally, we discuss emerging innovative technologies and potential clinical interventions targeting the ANS as a strategy to restore the normal regulation of the immune response in individuals with SCI.

Transspinal Focused Ultrasound Suppresses Spinal Reflexes in Healthy Rats

OBJECTIVES

Low-intensity, focused ultrasound (FUS) is an emerging noninvasive neuromodulation approach, with improved spatial and temporal resolution and penetration depth compared to other noninvasive electrical stimulation strategies. FUS has been used to modulate circuits in the brain and the peripheral nervous system, however, its potential to modulate spinal circuits is unclear. In this study, we assessed the effect of trans-spinal FUS (tsFUS) on spinal reflexes in healthy rats.

MATERIALS AND METHODS

tsFUS targeting different spinal segments was delivered for 1 minute, under anesthesia. Monosynaptic H-reflex of the sciatic nerve, polysynaptic flexor reflex of the sural nerve, and withdrawal reflex tested with a hot plate were measured before, during, and after tsFUS.

RESULTS

tsFUS reversibly suppresses the H-reflex in a spinal segment-, acoustic pressure- and pulse-repetition frequency (PRF)-dependent manner. tsFUS with high PRF augments the degree of homosynaptic depression of the H-reflex observed with paired stimuli. It suppresses the windup of components of the flexor reflex associated with slower, C-afferent, but not faster, A- afferent fibers. Finally, it increases the latency of the withdrawal reflex. tsFUS does not elicit neuronal loss in the spinal cord.

CONCLUSIONS

Our study provides evidence that tsFUS reversibly suppresses spinal reflexes and suggests that tsFUS could be a safe and effective strategy for spinal cord neuromodulation in disorders associated with hyperreflexia, including spasticity after spinal cord injury and painful syndromes.

A fully autonomous robotic ultrasound system for thyroid scanning

The current thyroid ultrasound relies heavily on the experience and skills of the sonographer and the expertise of the radiologist, and the process is physically and cognitively exhausting. In this paper, we report a fully autonomous robotic ultrasound system, which is able to scan thyroid regions without human assistance and identify malignant nod- ules. In this system, human skeleton point recognition, reinforcement learning, and force feedback are used to deal with the difficulties in locating thyroid targets. The orientation of the ultrasound probe is adjusted dynamically via Bayesian optimization. Experimental results on human participants demonstrated that this system can perform high-quality ultrasound scans, close to manual scans obtained by clinicians. Additionally, it has the potential to detect thyroid nodules and provide data on nodule characteristics for American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) calculation.

Bioelectronic modulation of carotid sinus nerve to treat type 2 diabetes: current knowledge and future perspectives

Bioelectronic medicine are an emerging class of treatments aiming to modulate body nervous activity to correct pathological conditions and restore health. Recently, it was shown that the high frequency electrical neuromodulation of the carotid sinus nerve (CSN), a small branch of the glossopharyngeal nerve that connects the carotid body (CB) to the brain, restores metabolic function in type 2 diabetes (T2D) animal models highlighting its potential as a new therapeutic modality to treat metabolic diseases in humans. In this manuscript, we review the current knowledge supporting the use of neuromodulation of the CSN to treat T2D and discuss the future perspectives for its clinical application. Firstly, we review in a concise manner the role of CB chemoreceptors and of CSN in the pathogenesis of metabolic diseases. Secondly, we describe the findings supporting the potential therapeutic use of the neuromodulation of CSN to treat T2D, as well as the feasibility and reversibility of this approach. A third section is devoted to point up the advances in the neural decoding of CSN activity, in particular in metabolic disease states, that will allow the development of closed-loop approaches to deliver personalized and adjustable treatments with minimal side effects. And finally, we discuss the findings supporting the assessment of CB activity in metabolic disease patients to screen the individuals that will benefit therapeutically from this bioelectronic approach in the future.

Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies

Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies. Given the emergency of accelerating the progress in new neuromodulation treatments (i.e., drug-resistant hypertension, autoimmune and degenerative diseases), collaboration between multiple fields is imperative. This work intends to foster multidisciplinary work and bring together different fields to provide the fundamental basis underlying Bioelectronic Medicine. In this review we will go from the biophysics of the cell membrane, which we consider the inner core of neuromodulation, to patient care. We will discuss the recently discovered mechanism of neurotransmission switching and how it will impact neuromodulation design, and we will provide an update on neuronal and glial basis in health and disease. The advances in biomedical technology have facilitated the collection of large amounts of data, thereby introducing new challenges in data analysis. We will discuss the current approaches and challenges in high throughput data analysis, encompassing big data, networks, artificial intelligence, and internet of things. Emphasis will be placed on understanding the electrochemical properties of neural interfaces, along with the integration of biocompatible and reliable materials and compliance with biomedical regulations for translational applications. Preclinical validation is foundational to the translational process, and we will discuss the critical aspects of such animal studies. Finally, we will focus on the patient point-of-care and challenges in neuromodulation as the ultimate goal of bioelectronic medicine. This review is a call to scientists from different fields to work together with a common endeavor: accelerate the decoding and modulation of the nervous system in a new era of therapeutic possibilities.

Low-intensity pulsed ultrasound activated the anti-tumor immunity by irradiating the spleen of mice in 4 T-1 breast cancer

Tumor immunotherapy is booming around the world. However, strategies to activate the immune system and alleviate the immunosuppression still need to be refined. Here, we demonstrate for the first time that low-intensity pulsed ultrasound (LIPUS, spatial average time average intensity (Isata) is 200 mW/cm2, frequency is 0.3 MHz, repetition frequency is 1 kHz, and duty cycle is 20%) triggers the immune system and further reverses the immunosuppressive state in the mouse models of breast cancer by irradiating the spleen of mice. LIPUS inhibited tumor growth and extended survival in mice with 4 T-1 tumors. Further studies had previously shown that LIPUS enhanced the activation of CD4+ and CD8+ T cells in the spleen and led to significant changes in cytokines, as well as induced upregulation of mRNA levels involved in multiple immune regulatory pathways in the spleen. In addition, LIPUS promoted tumor-infiltrating lymphocyte accumulation and CD8+ T cell activation and improved the dynamics of cytokines/chemokines in the tumor microenvironment, resulting in a reversal of the immunosuppressive state of the tumor microenvironment. These results suggest a novel approach to activate the immune response by irradiating the spleen with LIPUS.

Transthoracic Ultrasound Improves Cardiac Function in Mice

Cardiac dysfunction is a severe complication that is associated with an increased risk of mortality in multiple diseases. Cardioprotection solution that has been researched is the electrical stimulation of the vagus nerve to exert cardio protection. This method has been shown to reduce the systemic inflammatory response and maintain the immune homeostasis of the heart. However, the invasive procedure of electrode implantation poses a risk of nerve or fiber damage. Here, we propose transthoracic ultrasound stimulation (US) of the vagus nerve to alleviate cardiac dysfunction caused by lipopolysaccharide (LPS). We developed a noninvasive transthoracic US system and exposed anesthetized mice to ultrasound protocol or sham stimulation 24 h after LPS treatment. Results showed that daily heart targeting US for 4 days significantly increased left ventricular systolic function ( p = 0.01) and improved ejection fraction ( p = 0.03) and shortening fraction ( p = 0.04). Furthermore, US significantly reduced inflammation cytokines, including IL-6 ( p = 0.03) and IL- 1β ( p = 0.04). In addition, cervical vagotomy abrogated the effect of US, suggesting the involvement of the vagus nerve's anti-inflammatory effect. Finally, the same ultrasound treatment but for a longer period (14 days) also significantly increased cardiac function in naturally aged mice. Collectively, these findings suggest the potential of transthoracic US as a possible novel noninvasive approach in the context of cardiac dysfunction with reduced systolic function and provide new targets for rehabilitation of peripheral organ function.

Combined transcriptomics and proteomics studies on the effect of electrical stimulation on spinal cord injury in rats

Electrical stimulation (ES) of the spinal cord is a promising therapy for functional rehabilitation after spinal cord injury (SCI). However, the specific mechanism of action is poorly understood. We designed and applied an implanted ES device in the SCI area in rats and determined the effect of ES on the treatment of motor dysfunction after SCI using behavioral scores. Additionally, we examined the molecular characteristics of the samples using proteomic and transcriptomic sequencing. The differential molecules between groups were identified using statistical analyses. Molecular, network, and pathway-based analyses were used to identify group-specific biological features. ES (0.5 mA, 0.1 ms, 50 Hz) had a positive effect on motor dysfunction and neuronal regeneration in rats after SCI. Six samples (three independent replicates in each group) were used for transcriptome sequencing; we obtained 1026 differential genes, comprising 274 upregulated genes and 752 downregulated genes. A total of 10 samples were obtained: four samples in the ES group and six samples in the SCI group; for the proteome sequencing, 48 differential proteins were identified, including 45 up-regulated and three down-regulated proteins. Combined transcriptomic and proteomic studies have shown that the main enrichment pathway is the hedgehog signaling pathway. Western blot results showed that the expression levels of Sonic hedgehog (SHH) (P < 0.001), Smoothened (SMO) (P = 0.0338), and GLI-1 (P < 0.01) proteins in the ES treatment group were significantly higher than those in the SCI group. The immunofluorescence results showed significantly increased expression of SHH (P = 0.0181), SMO (P = 0.021), and GLI-1 (P = 0.0126) in the ES group compared with that in the SCI group. In conclusion, ES after SCI had a positive effect on motor dysfunction and anti-inflammatory effects in rats. Moreover, transcriptomic and proteomic sequencing also provided unique perspectives on the complex relationships between ES on SCI, where the SHH signaling pathway plays a critical role. Our study provides a significant theoretical foundation for the clinical implementation of ES therapy in patients with SCI.

Rib detection using pitch-catch ultrasound and classification algorithms for a novel ultrasound therapy device

BACKGROUND

Noninvasive ultrasound (US) has been used therapeutically for decades, with applications in tissue ablation, lithotripsy, and physical therapy. There is increasing evidence that low intensity US stimulation of organs can alter physiological and clinical outcomes for treatment of health disorders including rheumatoid arthritis and diabetes. One major translational challenge is designing portable and reliable US devices that can be used by patients in their homes, with automated features to detect rib location and aid in efficient transmission of energy to organs of interest. This feasibility study aimed to assess efficacy in rib bone detection without conventional imaging, using a single channel US pitch-catch technique integrated into an US therapy device to detect pulsed US reflections from ribs.

METHODS

In 20 healthy volunteers, the location of the ribs and spleen were identified using a diagnostic US imaging system. Reflected ultrasound signals were recorded at five positions over the spleen and adjacent ribs using the therapy device. Signals were classified as between ribs (intercostal), partially over a rib, or fully over a rib using four models: threshold-based time domain classification, threshold-based frequency domain classification, logistic regression, and support vector machine (SVM).

RESULTS

SVM performed best overall on the All Participants cohort with accuracy up to 96.25%. All models' accuracies were improved by separating participants into two cohorts based on Body Mass Index (BMI) and re-fitting each model. After separation into Low BMI and High BMI cohorts, a simple time-thresholding approach achieved accuracies up to 100% and 93.75%, respectively.

CONCLUSION

These results demonstrate that US reflection signal classification can accurately provide low complexity, real-time automated onboard rib detection and user feedback to advance at-home therapeutic US delivery.

Transcutaneous auricular vagus nerve stimulation in the treatment of disorders of consciousness: mechanisms and applications

This review provides an in-depth exploration of the mechanisms and applications of transcutaneous auricular vagus nerve stimulation (taVNS) in treating disorders of consciousness (DOC). Beginning with an exploration of the vagus nerve's role in modulating brain function and consciousness, we then delve into the neuroprotective potential of taVNS demonstrated in animal models. The subsequent sections assess the therapeutic impact of taVNS on human DOC, discussing the safety, tolerability, and various factors influencing the treatment response. Finally, the review identifies the current challenges in taVNS research and outlines future directions, emphasizing the need for large-scale trials, optimization of treatment parameters, and comprehensive investigation of taVNS's long-term effects and underlying mechanisms. This comprehensive overview positions taVNS as a promising and safe modality for DOC treatment, with a focus on understanding its intricate neurophysiological influence and optimizing its application in clinical settings.

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

BACKGROUND

The noradrenergic innervation of the spleen is implicated in the autonomic control of inflammation and has been the target of neurostimulation therapies for inflammatory diseases. However, there is no real-time marker of its successful activation, which hinders the development of anti-inflammatory neurostimulation therapies and mechanistic studies in anti-inflammatory neural circuits.

METHODS

In mice, we performed fast-scan cyclic voltammetry (FSCV) in the spleen during intravenous injections of norepinephrine (NE), and during stimulation of the vagus, splanchnic, or splenic nerves. We defined the stimulus-elicited charge generated at the oxidation potential for NE (~ 0.88 V) as the "NE voltammetry signal" and quantified the dependence of the signal on NE dose and intensity of neurostimulation. We correlated the NE voltammetry signal with the anti-inflammatory effect of splenic nerve stimulation (SpNS) in a model of lipopolysaccharide- (LPS) induced endotoxemia, quantified as suppression of TNF release.

RESULTS

The NE voltammetry signal is proportional to the estimated peak NE blood concentration, with 0.1 μg/mL detection threshold. In response to SpNS, the signal increases within seconds, returns to baseline minutes later, and is blocked by interventions that deplete NE or inhibit NE release. The signal is elicited by efferent, but not afferent, electrical or optogenetic vagus nerve stimulation, and by splanchnic nerve stimulation. The magnitude of the signal during SpNS is inversely correlated with subsequent TNF suppression in endotoxemia and explains 40% of the variance in TNF measurements.

CONCLUSIONS

FSCV in the spleen provides a marker for real-time monitoring of anti-inflammatory activation of the splenic innervation during autonomic stimulation.

A Bibliometric Analysis for Low-Intensity Ultrasound Study Over the Past Three Decades

Low-intensity ultrasound (LI-US) is a non-invasive stimulation technique that has emerged in recent years and has been shown to have positive effects on neuromodulation, fracture healing, inflammation improvement, and metabolic regulation. This study reports the conclusions of a bibliometric analysis of LI-US. Input data for the period between 1995 and 2022, including 7209 related articles in the field of LI-US, were collected from the core library of the Web of Science (WOS) database. Using these data, a set of bibliometric indicators was obtained to gain knowledge on different aspects: global production, research areas, and sources analysis, contributions of countries and institutions, author analysis, citation analysis, and keyword analysis. This study combined the data analysis capabilities provided by the WOS database, making use of two bibliometric software tools: R software and VOS viewer to achieve analysis and data exploration visualization, and predicted the further development trends of LI-US. It turns out that the United States and China are co-leaders while Zhang ZG is the most significant author in LI-US. In the future, the hot spots of LI-US will continue to focus on parameter research, mechanism discussion, safety regulations, and neuromodulation applications.

Investigation of liver-targeted peripheral focused ultrasound stimulation (pFUS) and its effect on glucose homeostasis and insulin resistance in type 2 diabetes mellitus: a proof of concept, phase 1 trial

BACKGROUND

Mechanical waves produced by ultrasound pulses have been shown to activate mechanosensitive ion channels and modulate peripheral nerves. However, while peripheral ultrasound neuromodulation has been demonstrated in vitro and in pre-clinical models, there have been few reports of clinical tests.

AIM

We modified a diagnostic imaging system for ultrasound neuromodulation in human subjects. We report the first safety and feasibility outcomes in subjects with type 2 diabetes (T2D) mellitus and discuss these outcomes in relation to previous pre-clinical results.

DESIGN

The study was performed as an open label feasibility study to assess the effects of hepatic ultrasound (targeted to the porta hepatis) on glucometabolic parameters in subjects with T2D. Stimulation (peripheral focused ultrasound stimulation treatment) was performed for 3 days (i.e. 15 min per day), preceded by a baseline examination and followed by a 2-week observation period.

METHODS

Multiple metabolic assays were employed including measures of fasting glucose and insulin, insulin resistance and glucose metabolism. The safety and tolerability were also assessed by monitoring adverse events, changes in vital signs, electrocardiogram parameters and clinical laboratory measures.

RESULTS AND CONCLUSION

We report post-pFUS trends in several outcomes that were consistent with previous pre-clinical findings. Fasting insulin was lowered, resulting in a reduction of HOMA-IR scores (P-value 0.01; corrected Wilcoxon signed-rank test). Additional safety and exploratory markers demonstrated no device-related adverse impact of pFUS. Our findings demonstrate that pFUS represents a promising new treatment modality that could be used as a non-pharmaceutical adjunct or even alternative to current drug treatments in diabetes.

Pharmacological and Electroceutical Targeting of the Cholinergic Anti-Inflammatory Pathway in Autoimmune Diseases

Continuous dialogue between the immune system and the brain plays a key homeostatic role in various immune responses to environmental cues. Several functions are under the control of the vagus nerve-based inflammatory reflex, a physiological mechanism through which nerve signals regulate immune functions. In the cholinergic anti-inflammatory pathway, the vagus nerve, its pivotal neurotransmitter acetylcholine, together with the corresponding receptors play a key role in modulating the immune response of mammals. Through communications of peripheral nerves with immune cells, it modulates proliferation and differentiation activities of various immune cell subsets. As a result, this pathway represents a potential target for treating autoimmune diseases characterized by overt inflammation and a decrease in vagal tone. Consistently, converging observations made in both animal models and clinical trials revealed that targeting the cholinergic anti-inflammatory pathway using pharmacologic approaches can provide beneficial effects. In parallel, bioelectronic medicine has recently emerged as an alternative approach to managing systemic inflammation. In several studies, nerve electrostimulation was reported to be clinically relevant in reducing chronic inflammation in autoimmune diseases, including rheumatoid arthritis and diabetes. In the future, these new approaches could represent a major therapeutic strategy for autoimmune and inflammatory diseases.

Anti-inflammatory Effect of Low-Intensity Ultrasound in Septic Rats

OBJECTIVE

Sepsis is a severe systemic inflammatory response caused by infection. Here, the spleen region of Sprague-Dawley (SD) rats with sepsis was irradiated with low-intensity ultrasound (LIUS) to explore the regulation of inflammation and its mechanism by LIUS.

METHODS

In this study, 30 rats used for survival analysis were randomly divided into the sham-operated group (Sham, n = 10), the group in which sepsis was induced by cecal ligation and puncture (CLP, n = 10) and the group treated with LIUS immediately after CLP (LIUS, n = 10). The other 120 rats were randomly divided into the aforementioned three groups for detection at each time point. The parameters used in the LIUS group were 200 mW/cm², 0.37 MHz, 20% duty cycle and 20 min, and no ultrasonic energy was produced in the Sham and CLP groups. Seven-day survival rate, histopathology and expression of inflammatory factors and proteins were evaluated in the three groups.

RESULTS

LIUS was able to improve the survival rate of septic SD rats (p < 0.05), significantly inhibit the expression of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), interleukin 6 (IL-6) and nuclear factor-κB p65 (NF-κB p65) (p < 0.05) and restore the ultrastructure of the spleen.

CONCLUSION

Our study determined that LIUS can relieve spleen damage and alleviate severe cytokine storm to improve survival outcomes in septic SD rats, and its mechanism may be related to the inhibition of the NF-κB signaling pathway by downregulation of IL-1β.

Neuroprotection by Abdominal Ultrasound in Lipopolysaccharide-Induced Systemic Inflammation

Systemic inflammation is associated with intestinal inflammation and neuroinflammation by imbalancing the gut-brain axis. Low-intensity pulsed ultrasound (LIPUS) has neuroprotective and anti-inflammatory effects. This study explored LIPUS's neuroprotective effects against lipopolysaccharide (LPS)-induced neuroinflammation through transabdominal stimulation. Male C57BL/6J mice were intraperitoneally injected with LPS (0.75 mg/kg) daily for seven days, and abdominal LIPUS was applied to the abdominal area for 15 min/day during the last six days. One day after the last LIPUS treatment, biological samples were collected for microscopic and immunohistochemical analysis. Histological examination showed that LPS administration leads to tissue damage in the colon and brain. Transabdominal LIPUS stimulation attenuated colonic damage, reducing histological score, colonic muscle thickness, and villi shortening. Furthermore, abdominal LIPUS reduced hippocampal microglial activation (labeled by ionized calcium-binding adaptor molecule-1 [Iba-1]) and neuronal cell loss (labeled by microtubule-associated protein 2 [MAP2]). Moreover, abdominal LIPUS attenuated the number of apoptotic cells in the hippocampus and cortex. Altogether, our results indicate that abdominal LIPUS stimulation attenuates LPS-induced colonic inflammation and neuroinflammation. These findings provide new insights into the treatment strategy for neuroinflammation-related brain disorders and may facilitate method development through the gut-brain axis pathway.

Focused ultrasound neuromodulation of the spleen activates an anti-inflammatory response in humans

Focused ultrasound stimulation (FUS) activates mechanosensitive ion channels and is emerging as a method of noninvasive neuromodulation. In preclinical studies, FUS of the spleen (sFUS) activates an anti-inflammatory neural pathway which suppresses acute and chronic inflammation. However, the relevance of sFUS for regulating inflammatory responses in humans is unknown. Here, we used a modified diagnostic ultrasound imaging system to target the spleen of healthy human subjects with 3 min of continuously swept or stationary focused pulsed ultrasound, delivered at three different energy levels within allowable safety exposure limits. Potential anti-inflammatory effects of sFUS were assessed by measuring sFUS-elicited changes in endotoxin-induced tumor necrosis factor (TNF) production in whole blood samples from insonified subjects. We found that stimulation with either continuously swept or focused pulsed ultrasound has an anti-inflammatory effect: sFUS lowers TNF production for >2 h, with TNF returning to baseline by 24 h following sFUS. This response is independent of anatomical target (i.e., spleen hilum or parenchyma) or ultrasound energy level. No clinical, biochemical, or hematological parameters are adversely impacted. This is the first demonstration that sFUS suppresses the normal inflammatory response in humans, with potential implications for noninvasive bioelectronic therapy of inflammatory disorders.

Noninvasive ultrasound stimulation to treat myocarditis through splenic neuro-immune regulation

BACKGROUND

The cholinergic anti-inflammatory pathway (CAP) has been widely studied to modulate the immune response. Current stimulating strategies are invasive or imprecise. Noninvasive low-intensity pulsed ultrasound (LIPUS) has become increasingly appreciated for targeted neuronal modulation. However, its mechanisms and physiological role on myocarditis remain poorly defined.

METHODS

The mouse model of experimental autoimmune myocarditis was established. Low-intensity pulsed ultrasound was targeted at the spleen to stimulate the spleen nerve. Under different ultrasound parameters, histological tests and molecular biology were performed to observe inflammatory lesions and changes in immune cell subsets in the spleen and heart. In addition, we evaluated the dependence of the spleen nerve and cholinergic anti-inflammatory pathway of low-intensity pulsed ultrasound in treating autoimmune myocarditis in mice through different control groups.

RESULTS

The echocardiography and flow cytometry of splenic or heart infiltrating immune cells revealed that splenic ultrasound could alleviate the immune response, regulate the proportion and function of CD4+ Treg and macrophages by activating cholinergic anti-inflammatory pathway, and finally reduce heart inflammatory injury and improve cardiac remodeling, which is as effective as an acetylcholine receptor agonists GTS-21. Transcriptome sequencing showed significant differential expressed genes due to ultrasound modulation.

CONCLUSIONS

It is worth noting that the ultrasound therapeutic efficacy depends greatly on acoustic pressure and exposure duration, and the effective targeting organ was the spleen but not the heart. This study provides novel insight into the therapeutic potentials of LIPUS, which are essential for its future application.

Neuroimmune nexus in the pathophysiology and therapy of inflammatory disorders: role of α7 nicotinic acetylcholine receptors

The α7-nicotinic acetylcholine receptor (α7nAChR) is a key protein in the cholinergic anti-inflammatory pathway (CAP) that links the nervous and immune systems. Initially, the pathway was discovered based on the observation that vagal nerve stimulation (VNS) reduced the systemic inflammatory response in septic animals. Subsequent studies form a foundation for the leading hypothesis about the central role of the spleen in CAP activation. VNS evokes noradrenergic stimulation of ACh release from T cells in the spleen, which in turn activates α7nAChRs on the surface of macrophages. α7nAChR-mediated signaling in macrophages reduces inflammatory cytokine secretion and modifies apoptosis, proliferation, and macrophage polarization, eventually reducing the systemic inflammatory response. A protective role of the CAP has been demonstrated in preclinical studies for multiple diseases including sepsis, metabolic disease, cardiovascular diseases, arthritis, Crohn's disease, ulcerative colitis, endometriosis, and potentially COVID-19, sparking interest in using bioelectronic and pharmacological approaches to target α7nAChRs for treating inflammatory conditions in patients. Despite a keen interest, many aspects of the cholinergic pathway are still unknown. α7nAChRs are expressed on many other subsets of immune cells that can affect the development of inflammation differently. There are also other sources of ACh that modify immune cell functions. How the interplay of ACh and α7nAChR on different cells and in various tissues contributes to the anti-inflammatory responses requires additional study. This review provides an update on basic and translational studies of the CAP in inflammatory diseases, the relevant pharmacology of α7nAChR-activated drugs and raises some questions that require further investigation.

Development of Spleen Targeting H2S Donor Loaded Liposome for the Effective Systemic Immunomodulation and Treatment of Inflammatory Bowel Disease

Nanoparticles are primarily taken up by immune cells after systemic administration. Thus, they are considered an ideal drug delivery vehicle for immunomodulation. Because the spleen is the largest lymphatic organ and regulates the systemic immune system, there have been studies to develop spleen targeting nanoparticles for immunomodulation of cancer and immunological disorders. Inflammatory bowel disease (IBD) includes disorders involving chronic inflammation in the gastrointestinal tract and is considered incurable despite a variety of treatment options. Hydrogen sulfide (H₂S) is one of the gasotransmitters that carries out anti-inflammatory functions and has shown promising immunomodulatory effects in various inflammatory diseases including IBD. Herein, we developed a delicately tuned H₂S donor delivering liposome for spleen targeting (ST-H₂S lipo) and studied its therapeutic effects in a dextran sulfate sodium (DSS) induced colitis model. We identified the ideal PEG type and ratio of liposome for a high stability, loading efficiency, and spleen targeting effect. In the treatment of the DSS-induced colitis model, we found that ST-H₂S lipo and conventional long-circulating liposomes loaded with H₂S donors (LC-H₂S lipo) reduced the severity of colitis, whereas unloaded H₂S donors did not. Furthermore, the therapeutic effect of ST-H₂S lipo was superior to that of LC-H₂S lipo due to its better systemic immunomodulatory effect than that of LC-H₂S lipo. Our findings demonstrate that spleen targeting H₂S lipo may have therapeutic potential for IBD.

Nanomedicine is more than a supporting role in rheumatoid arthritis therapy

Rheumatoid arthritis(RA) is an autoimmune disorder that affects the joints. Various medications successfully alleviate the symptoms of RA in clinical. Still, few therapy strategies can cure RA, especially when joint destruction begins, and there is currently no effective bone-protective treatment to reverse the articular damage. Furthermore, the RA medications now used in clinical practice accompany various adverse side effects. Nanotechnology can improve the pharmacokinetics of traditional anti-RA drugs and therapeutic precision through targeting modification. Although the clinical application of nanomedicines for RA is in its infancy, preclinical research is rising. Current anti-RA nano-drug studies mainly focus on the following: drug delivery systems, nanomedicines with anti-inflammatory and anti-arthritic properties, biomimetic design with better biocompatibility and therapeutic features, and nanoparticle-dominated energy conversion therapies. These therapies have shown promising therapeutic benefits in animal models, indicating that nanomedicines are a potential solution to the current bottleneck in RA treatment. This review will summarize the present state of anti-RA nano-drug research.

Low-Intensity Focused Ultrasound Ameliorates Ischemic Heart Failure Related to the Cholinergic Anti-Inflammatory Pathway

OBJECTIVES

This study aims to determine the effect of low-intensity focused ultrasound (LIFU) in ischemic heart failure (IHF) and explore the potential neuroimmune mechanism.

METHODS

Sprague-Dawley rats were subjected to ultrasound (US) with specific parameters, and electrocardiograms were recorded to analyze the effect of LIFU and/or vagal denervation on heart rate. Thereafter, myocardial infarction (MI) was induced by left anterior artery ligation, and LIFU was performed three times a day for 25 days after MI. Echocardiography, Masson staining, and ELISA were used to evaluate the effect of LIFU on the structure and function of the heart. Finally, ELISA, flow cytometry, qRT-PCR, and Western blot analysis were performed to determine the effect of LIFU on the inflammation and the expression of the cholinergic anti-inflammatory pathway (CAP)-related mediators.

RESULTS

LIFU reduced heart rate in rats (control vs LIFU, P < .01), and vagotomy (VT) eliminated this effect of LIFU on heart rate (VT vs LIFU + VT, P > .01). LIFU-ameliorated IHF in terms of cardiac structure and function (MI vs MI + LIFU, P < .01), but VT abrogated the beneficial effect of LIFU (MI + VT vs MI + LIFU + VT, P > .01). After the treatment of LIFU, decreased levels of inflammatory cytokines, increased proportion of anti-inflammatory macrophages, and increased expression of CAP-related mediators (MI vs MI + LIFU, P < .01).

CONCLUSIONS

LIFU ameliorates IHF whereas the CAP plays a promising role. LIFU has the potential to be a novel nonpharmacological and noninvasive therapy for the treatment of coronary artery disease and other cardiovascular diseases.

Subthreshold splenic nerve stimulation prevents myocardial Ischemia-Reperfusion injury via neuroimmunomodulation of proinflammatory factor levels

OBJECTIVES

Clinical outcomes following myocardial ischemia-reperfusion (I/R) injury are strongly related to the intensity and duration of inflammation. The splenic nerve (SpN) is indispensable for the anti-inflammatory reflex. This study aimed to investigate whether splenic nerve stimulation (SpNS) plays a cardioprotective role in myocardial I/R injury and the potential underlying mechanism.

METHODS

Sprague-Dawley rats were randomly divided into four groups: sham group, I/R group, SpNS group, and I/R plus SpNS group. The highest SpNS intensity that did not influence heart rate was identified, and SpNS at this intensity was used as the subthreshold stimulus. Continuous subthreshold SpNS was applied for 1 h before ligation of the left coronary artery for 45 min. After 72 h of reperfusion, samples were collected for analysis.

RESULTS

SpN activity and splenic concentrations of cholinergic anti-inflammatory pathway (CAP)-related neurotransmitters were significantly increased by SpNS. The infarct size, oxidative stress, sympathetic tone, and the levels of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6, were significantly reduced in rats subjected to subthreshold SpNS after myocardial I/R injury compared with those subjected to I/R injury alone.

CONCLUSIONS

Subthreshold SpNS ameliorates myocardial damage, the inflammatory response, and cardiac remodelling induced by myocardial I/R injury via neuroimmunomodulation of proinflammatory factor levels. SpNS is a potential therapeutic strategy for the treatment of myocardial I/R injury.

Peripheral focused ultrasound stimulation and its applications: From therapeutics to human-computer interaction

Peripheral focused ultrasound stimulation (pFUS) has gained increasing attention in the past few decades, because it can be delivered to peripheral nerves, neural endings, or sub-organs. With different stimulation parameters, ultrasound stimulation could induce different modulation effects. Depending on the transmission medium, pFUS can be classified as body-coupled US stimulation, commonly used for therapeutics or neuromodulation, or as an air-coupled contactless US haptic system, which provides sensory inputs and allows distinct human-computer interaction paradigms. Despite growing interest in pFUS, the underlying working mechanisms remain only partially understood, and many applications are still in their infancy. This review focused on existing applications, working mechanisms, the latest progress, and future directions of pFUS. In terms of therapeutics, large-sample randomized clinical trials in humans are needed to translate these state of art techniques into treatments for specific diseases. The airborne US for human-computer interaction is still in its preliminary stage, but further efforts in task-oriented US applications might provide a promising interaction tool soon.

Sympathetic innervation of human and porcine spleens: implications for between species variation in function

BACKGROUND

The vagus nerve affects innate immune responses by activating spleen-projecting sympathetic neurons, which modulate leukocyte function. Recent basic and clinical research investigating vagus nerve stimulation to engage the cholinergic anti-inflammatory pathway (CAP) has shown promising therapeutic results for a variety of inflammatory diseases. Abundant sympathetic innervation occurs in rodent spleens, and use of these species has dominated mechanistic research investigating the CAP. However, previous neuroanatomical studies of human spleen found a more restricted pattern of innervation compared to rodents. Therefore, our primary goal was to establish the full extent of sympathetic innervation of human spleens using donor tissue with the shortest procurement to fixation time. Parallel studies of porcine spleen, a large animal model, were performed as a positive control and for comparison.

METHODS

Human and porcine spleen tissue were fixed immediately after harvest and prepared for immunohistochemistry. Human heart and porcine spleen were stained in conjunction as positive controls. Several immunohistochemical protocols were compared for best results. Tissue was stained for tyrosine hydroxylase (TH), a noradrenergic marker, using VIP purple chromogen. Consecutive tissue slices were stained for neuropeptide Y (NPY), which often co-localizes with TH, or double-labelled for TH and CD3, a T cell marker. High-magnification images and full scans of the tissue were obtained and analyzed for qualitative differences between species.

RESULTS

TH had dominant perivascular localization in human spleen, with negligible innervation of parenchyma, but such nerves were abundant throughout ventricular myocardium. In marked contrast, noradrenergic innervation was abundant in all regions of porcine spleen, with red pulp having more nerves than white pulp. NPY stain results were consistent with this pattern. In human spleen, noradrenergic nerves only ran close to T cells at the boundary of the periarterial lymphatic sheath and arteries. In porcine spleen, noradrenergic nerves were closely associated with T cells in both white and red pulp as well as other leukocytes in red pulp.

CONCLUSION

Sympathetic innervation of the spleen varies between species in both distribution and abundance, with humans and pigs being at opposite extremes. This has important implications for sympathetic regulation of neuroimmune interactions in the spleen of different species and focused targeting of the CAP in humans.

Noninvasive Low-Frequency Pulsed Focused Ultrasound Therapy for Rheumatoid Arthritis in Mice

Rheumatoid arthritis (RA) is a common autoimmune disease characterized by chronic and progressive inflammation of the synovium. Focused ultrasound therapy is an increasingly attractive alternative for treating RA owing to its noninvasiveness; however, it remains unclear which immune subsets respond to ultrasound stimulation. In this study, we showed that spleen-targeted low-frequency pulsed focused ultrasound (LFPFU) effectively improved the severity of arthritis in an arthritis mouse model established in DBA/1J mice. Additionally, we performed in-depth immune profiling of spleen samples from RA mice, RA mice that underwent ultrasound therapy, and healthy controls using mass cytometry along with extensive antibody panels and identified the immune composition of 14 cell populations, including CD4+/CD8+ T cells, B cells, natural killer cells, and dendritic cells. Moreover, multidimensional analysis according to cell-surface markers and phenotypes helped in identifying 4 and 5 cell subpopulations among T and myeloid cells, respectively, with 6 T cell subsets and 3 myeloid cell subsets responsive to ultrasound therapy among the 3 groups. Of these cell subsets, CD8+ T cell subsets showed a unique response to ultrasound stimulation in RA mice. Specifically, CD8+ T cells show a noticeable correlation with the degree of arthritis progression and could serve as an indicator for spleen-focused ultrasound-based therapy. Furthermore, single-cell RNA sequencing of spleen cells revealed the importance of T, B, and myeloid cell populations in the anti-inflammatory pathway. These results elucidated the unique cell subsets and transcriptome of splenic cells responsive to LFPFU and demonstrated the potential of spleen-focused ultrasound stimulation in the treatment of inflammatory diseases.

Bioelectronic medicine: Preclinical insights and clinical advances

The nervous system maintains homeostasis and health. Homeostatic disruptions underlying the pathobiology of many diseases can be controlled by bioelectronic devices targeting CNS and peripheral neural circuits. New insights into the regulatory functions of the nervous system and technological developments in bioelectronics drive progress in the emerging field of bioelectronic medicine. Here, we provide an overview of key aspects of preclinical research, translation, and clinical advances in bioelectronic medicine.

LncRNA Gm26917 regulates inflammatory response in macrophages by enhancing Annexin A1 ubiquitination in LPS-induced acute liver injury

Long noncoding RNAs (lncRNAs) are defined as transcripts of more than 200 nucleotides that have little or no coding potential. LncRNAs function as key regulators in diverse physiological and pathological processes. However, the roles of lncRNAs in lipopolysaccharide (LPS)-induced acute liver injury (ALI) are still elusive. In this study, we report the roles of lncRNA Gm26917 induced by LPS in modulating liver inflammation. As key components of the innate immune system, macrophages play critical roles in the initiation, progression and resolution of ALI. Our studies demonstrated that Gm26917 localized in the cytoplasm of hepatic macrophages and globally regulated the expression of inflammatory genes and the differentiation of macrophages. In vivo study showed that lentivirus-mediated gene silencing of Gm26917 attenuated liver inflammation and protected mice from LPS-induced ALI. Furthermore, mechanistic study showed that the 3'-truncation of Gm26917 interacted with the N-terminus of Annexin A1, a negative regulator of the NF-κB signaling pathway. We also found that Gm26917 knockdown suppressed NF-κB activity by decreasing the ubiquitination of Annexin A1 and its interaction with NEMO. In addition, expression of Gm26917 in inflammatory macrophages was regulated by the transcription factor forkhead box M1 (FOXM1). LPS treatment dramatically increased the binding of FOXM1 to the promoter region of Gm26917 in macrophages. In summary, our findings suggest that lncRNA Gm26917 silencing protects against LPS-induced liver injury by regulating the TLR4/NF-κB signaling pathway in macrophages.

Manipulation of the inflammatory reflex as a therapeutic strategy

The cholinergic anti-inflammatory pathway is the efferent arm of the inflammatory reflex, a neural circuit through which the CNS can modulate peripheral immune responses. Signals communicated via the vagus and splenic nerves use acetylcholine, produced by Choline acetyltransferase (ChAT)+ T cells, to downregulate the inflammatory actions of macrophages expressing α7 nicotinic receptors. Pre-clinical studies using transgenic animals, cholinergic agonists, vagotomy, and vagus nerve stimulation have demonstrated this pathway's role and therapeutic potential in numerous inflammatory diseases. In this review, we summarize what is understood about the inflammatory reflex. We also demonstrate how pre-clinical findings are being translated into promising clinical trials, and we draw particular attention to innovative bioelectronic methods of harnessing the cholinergic anti-inflammatory pathway for clinical use.

Neuromodulation Strategies to Reduce Inflammation and Improve Lung Complications in COVID-19 Patients

Since the outbreak of the COVID-19 pandemic, races across academia and industry have been initiated to identify and develop disease modifying or preventative therapeutic strategies has been initiated. The primary focus has been on pharmacological treatment of the immune and respiratory system and the development of a vaccine. The hyperinflammatory state ("cytokine storm") observed in many cases of COVID-19 indicates a prognostically negative disease progression that may lead to respiratory distress, multiple organ failure, shock, and death. Many critically ill patients continue to be at risk for significant, long-lasting morbidity or mortality. The human immune and respiratory systems are heavily regulated by the central nervous system, and intervention in the signaling of these neural pathways may permit targeted therapeutic control of excessive inflammation and pulmonary bronchoconstriction. Several technologies, both invasive and non-invasive, are available and approved for clinical use, but have not been extensively studied in treatment of the cytokine storm in COVID-19 patients. This manuscript provides an overview of the role of the nervous system in inflammation and respiration, the current understanding of neuromodulatory techniques from preclinical and clinical studies and provides a rationale for testing non-invasive neuromodulation to modulate acute systemic inflammation and respiratory dysfunction caused by SARS-CoV-2 and potentially other pathogens. The authors of this manuscript have co-founded the International Consortium on Neuromodulation for COVID-19 to advocate for and support studies of these technologies in the current coronavirus pandemic.

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 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.

Ultrasound Neuromodulation of the Spleen Has Time-Dependent Anti-Inflammatory Effect in a Pneumonia Model

Interfaces between the nervous and immune systems have been shown essential for the coordination and regulation of immune responses. Non-invasive ultrasound stimulation targeted to the spleen has recently been shown capable of activating one such interface, the splenic cholinergic anti-inflammatory pathway (CAP). Over the past decade, CAP and other neuroimmune pathways have been activated using implanted nerve stimulators and tested to prevent cytokine release and inflammation. However, CAP studies have typically been performed in models of severe, systemic (e.g., endotoxemia) or chronic inflammation (e.g., collagen-induced arthritis or DSS-induced colitis). Herein, we examined the effects of activation of the splenic CAP with ultrasound in a model of local bacterial infection by lung instillation of 10⁵ CFU of Streptococcus pneumoniae. We demonstrate a time-dependent effect of CAP activation on the cytokine response assay during infection progression. CAP activation-induced cytokine suppression is absent at intermediate times post-infection (16 hours following inoculation), but present during the early (4 hours) and later phases (48 hours). These results indicate that cytokine inhibition associated with splenic CAP activation is not observed at all timepoints following bacterial infection and highlights the importance of further studying neuroimmune interfaces within the context of different immune system and inflammatory states.