The cholinergic anti-inflammatory pathway inhibits inflammation without lymphocyte relay

Beta Adrenergic Signaling as a Therapeutic Target for Autoimmunity

Background

We recently identified a molecular mechanism involving beta-adrenergic 1 and 2 receptors (β1/2) in the development of T H 17 lymphocytes. Pharmacological and genetic inhibition of these receptors in combination, but not separately, impaired the ability of T-lymphocytes to produce proinflammatory interleukin 17A (IL-17A) and instead promoted the production of protective T reg cells that secrete anti-inflammatory interleukin-10 (IL-10). However, it remained unclear whether this regulatory mechanism could serve as a novel therapeutic approach for autoimmune disorders mediated by IL-17A-producing T-lymphocytes.

Methods

Multiple sclerosis (MS) is an inflammatory demyelinating disorder of the central nervous system (CNS) characterized by an autoimmune response where both T-lymphocytes and IL-17A are implicated in the pathogenesis of the disease. Using an animal model of MS, termed experimental autoimmune encephalomyelitis (EAE), we addressed the impact of beta adrenergic receptor blockade (genetically and pharmacologically) on EAE disease progression, severity, and T H 17/T reg balance.

Results

The genetic deletion β1/2 receptors, either systemically or specifically in T-lymphocytes, significantly attenuated EAE disease severity and animal weight loss. Pharmacological blockade of β1/2 receptors with either propranolol (lipophilic) or nadolol (aqueous) limited disease severity and weight loss similar to the genetic models. All models showed degrees of shifted T H 17/T reg balance (suppressing T H 17 and promoting T reg ) and decreased T-lymphocyte IL-17A production. Importantly, pharmacological blockade was initiated at the time of symptom development, which mimics the typical time where diagnosis of disease would occur.

Conclusions

Our data depict a novel role for β1/2 adrenergic signaling in the control of T H 17/T reg cells in EAE. These findings provide new insight into the disease progression as well as provide a potential new pharmacological therapy for IL-17A-related autoimmune diseases.

Advancing Therapeutic Solutions for Burn Wounds: Potential Use of Noninvasive Ultrasound-Driven Splenic Stimulation

Significance: Burn wound injuries are a global health challenge, affecting millions annually and resulting in significant morbidity, mortality, and economic burden. The urgent need for accessible and cost-effective therapeutic alternatives, especially for underserved populations, has driven interest in novel approaches such as noninvasive splenic stimulation using pulsed-focused ultrasound (pFUS). This technique targets systemic inflammation, a key factor in delayed wound healing, offering a potential shift in burn care management. Recent Advances: Preclinical studies have shown that pFUS applied to the spleen can accelerate wound healing by activating the cholinergic anti-inflammatory pathway, promoting pro-angiogenic and anti-inflammatory responses. While current treatments-including biologics, antioxidants, and growth factors-have limitations, pFUS presents a noninvasive alternative. One interventional study and ongoing clinical trials are now investigating its application in burn wound care, marking an important step toward clinical translation. Critical Issues: Despite encouraging results, research on splenic stimulation for wound healing remains limited. The small number of studies highlights the need for further investigation into the underlying mechanisms, optimal treatment parameters, and potential risks. Additionally, the scalability and cost-effectiveness of pFUS in diverse clinical settings require thorough evaluation. Future Directions: Ongoing clinical trials will provide critical data on the efficacy and safety of splenic pFUS in burn patients. Future research should focus on expanding clinical studies, refining stimulation protocols, and exploring its broader application in tissue repair. If validated, this approach could offer a cost-effective, noninvasive treatment, particularly valuable in socioeconomically challenged regions.

Low-Frequency Electrical Stimulation of the Auricular Branch of the Vagus Nerve in Patients with ST-Elevation Myocardial Infarction: A Randomized Clinical Trial

Background: Despite the vast evidence of the beneficial effect of vagus nerve stimulation on the course of myocardial infarction confirmed in studies using animal models, the introduction of this method into actual clinical practice remains uncommon. Objective: The objective of our study was to evaluate the effect of transcutaneous vagus nerve stimulation (tVNS) on in-hospital and long-term outcomes for patients with ST-elevation myocardial infarction. Materials and Methods: A blind, randomized, placebo-controlled clinical trial was conducted. The participants were randomly split into two groups. The Active tVNS group was subjected to stimulation of the tragus containing the auricular branch of the vagus nerve. The Sham tVNS group underwent stimulation of the lobule. Stimulation was performed immediately on admission before the start of the percutaneous coronary intervention (PCI). Then, tVNS continued throughout the entire PCI procedure and 30 min after its completion. The primary endpoints were hospital mortality and 12-month mortality. The secondary endpoints were in-hospital and remote non-lethal cardiovascular events. The combined endpoint consisted of major adverse cardiovascular events (MACEs)-recurrent myocardial infarction, stroke/TIA, and overall mortality. Results: A total of 110 patients were randomized into the Active tVNS group (n = 55) and the Sham tVNS group (n = 55). The incidences of hospital mortality, cardiogenic shock, and AV block 3 were statistically less common in the Active tVNS group than in the Sham tVNS group (p = 0.024*, p = 0.044*, and p = 0.013*, respectively). In the long-term period, no statistical differences were found in the studied outcomes obtained following the construction of Kaplan-Meyer survival curves. When comparing groups by total mortality, taking into account hospital mortality, we observed a tendency for the survival curves to diverge (Logrank test, p = 0.066). Statistical significance was revealed by the composite endpoint, taking into account hospital events (Logrank test, p = 0.0016*). Conclusions: tVNS significantly reduced hospital mortality (p = 0.024*), the level of markers of myocardial damage, and the frequency of severe cardiac arrhythmias in patients with acute myocardial infarction. In the long term, the prognostic value of tVNS was revealed by the composite endpoint major adverse cardiovascular events. Further studies with an expanded sample are needed for a more detailed verification of the data obtained to confirm the effectiveness of tVNS and allow an in-depth analysis of the safety and feasibility of its use in routine clinical practice. This clinical trial is registered with ClinicalTrials database under a unique identifier: NCT05992259.

The synergistic effects of citicoline and silymarin on liver injury and thyroid hormone disturbances in γ-irradiated rats

BACKGROUND

Exposure to ionizing radiation is inevitable due to its extensive use in industrial and medical applications. The search for effective and safe natural therapeutic agents as alternatives to chemical drugs is crucial to mitigate their side effects. This study aimed to evaluate the effects of citicoline as a standalone treatment or in combination with the anti-hepatotoxic drug silymarin in protecting against liver injury caused by γ-radiation in rats.

METHODS AND RESULTS

The rats were exposed to γ-radiation (7 Gy) and treated with citicoline (300 mg/kg/day) and/or silymarin (50 mg/kg/day). The results showed that citicoline alleviated liver damage in irradiated rats by reducing hepatic malondialdehyde levels, serum aspartate aminotransferase activity, and inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and nuclear factor-kappa B (NF-κB). It also increased acetylcholine (ACh) levels and the gene expression of the anti-inflammatory protein α7 nicotinic acetylcholine receptor (α7nAChR). Additionally, citicoline improved serum triiodothyronine (T3) levels, thyroid hormone receptor beta (TRβ) gene expression, and iodothyronine deiodinase type 1 activity in hepatic tissues of irradiated rats. Furthermore, citicoline enhanced the effects of silymarin on thyroxine (T4), TRβ, ACh, and α7nAChR when co-administered in irradiated rats. Histopathological analysis confirmed these findings, demonstrating improved liver tissue structure.

CONCLUSIONS

Citicoline mitigates γ-radiation-induced liver damage by reducing oxidative stress, activating the cholinergic anti-inflammatory pathway, and modulating thyroid hormone metabolism. These findings support the use of citicoline as a safe standalone treatment or as an adjuvant with silymarin for managing liver damage and thyroid hormone disturbances caused by γ-irradiation.

TH17/Treg lymphocyte balance is regulated by beta adrenergic and cAMP signaling

BACKGROUND

Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a mouse model of repeated social defeat stress (RSDS) that recapitulates certain features of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear.

METHODS

Using a modified version of RSDS that allows for both males and females, as well as ex vivo models of T-lymphocyte polarization, we assessed the impact and mechanism of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte differentiation to IL-17A-producing subtypes (i.e., TH17).

RESULTS

Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (β1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g.,IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global β1/2 receptor knock-out mice, as well as by adoptively transferring β1/2 knock-out T-lymphocytes into immunodeficient hosts. Ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of β1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Furthermore, cyclic AMP (cAMP) was demonstrated to be mechanistically involved in driving IL-17A production in T-lymphocytes, and amplifying cAMP signaling could restore IL-17A deficits caused by the absence of β1/2 signaling. Last, removal of β1/2 and cAMP signaling, even in IL-17A polarizing conditions, promoted regulatory T-lymphocyte (Treg) polarization, suggesting adrenergic signaling plays a role in the switching between pro- and anti-inflammatory T-lymphocyte subtypes.

CONCLUSIONS

Our data depict a novel role for β1/2 adrenergic and cAMP signaling in the balance of TH17/Treg lymphocytes. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

Micellar Choline-Acetyltransferase Complexes Exhibit Ultra-Boosted Catalytic Rate for Acetylcholine Synthesis-Mechanistic Insights for Development of Acetylcholine-Enhancing Micellar Nanotherapeutics

Choline-acetyltransferase (ChAT) is the key cholinergic enzyme responsible for the biosynthesis of acetylcholine (ACh), a crucial signaling molecule with both canonical neurotransmitter function and auto- and paracrine signaling activity in non-neuronal cells, such as lymphocytes and astroglia. Cholinergic dysfunction is linked to both neurodegenerative and inflammatory diseases. In this study, we investigated a serendipitous observation, namely that the catalytic rate of human recombinant ChAT (rhChAT) protein greatly differed in buffered solution in the presence and absence of Triton X-100 (TX100). At a single concentration of 0.05% (v/v), TX100 boosted the specific activity of rhChAT by 4-fold. Dose-response analysis within a TX100 concentration range of 0.8% to 0.008% (accounting for 13.7 mM to 0.013 mM) resulted in an S-shaped response curve, indicative of an over 10-fold boost in the catalytic rate of rhChAT. This dramatic boost was unlikely due to a mere structural stabilization since it remained even after the addition of 1.0 mg/mL gelatin to the ChAT solution as a protein stabilizer. Furthermore, we found that the catalytic function of the ACh-degrading enzyme, AChE, was unaffected by TX100, underscoring the specificity of the effect for ChAT. Examination of the dose-response curve in relation to the critical micelle concentration (CMC) of TX100 revealed that a boost in ChAT activity occurred when the TX100 concentration passed its CMC, indicating that formation of micelle-ChAT complexes was crucial. We challenged this hypothesis by repeating the experiment on Tween 20 (TW20), another non-ionic surfactant with ~3-fold lower CMC compared to TX100 (0.06 vs. 0.2 mM). The analysis confirmed that micelle formation is crucial for ultra-boosting the activity of ChAT. In silico molecular dynamic simulation supported the notion of ChAT-micelle complex formation. We hypothesize that TX100 or TW20 micelles, by mimicking cell-membrane microenvironments, facilitate ChAT in accessing its full catalytic potential by fine-tuning its structural stabilization and/or enhancing its substrate accessibility. These insights are expected to facilitate research toward the development of new cholinergic-enhancing therapeutics through the formulation of micelle-embedded ChAT nanoparticles.

Heart rate variability and autonomic nervous system imbalance: Potential biomarkers and detectable hallmarks of aging and inflammaging

The most cutting-edge issue in the research on aging is the quest for biomarkers that transcend molecular and cellular domains to encompass organismal-level implications. We recently hypothesized the role of Autonomic Nervous System (ANS) imbalance in this context. Studies on ANS functions during aging highlighted an imbalance towards heightened sympathetic nervous system (SNS) activity, instigating a proinflammatory milieu, and attenuated parasympathetic nervous system (PNS) function, which exerts anti-inflammatory effects via the cholinergic anti-inflammatory pathway (CAP) and suppression of the hypothalamic-pituitary-adrenal (HPA) axis. This scenario strongly suggests that ANS imbalance can fuel inflammaging, now recognized as one of the most relevant risk factors for age-related disease development. Recent recommendations have increasingly highlighted the need for actionable strategies to improve the quality of life for older adults by identifying biomarkers that can be easily measured, even in asymptomatic individuals. We advocate for considering ANS imbalance as a biomarker of aging and inflammaging. Measures of ANS imbalance, such as heart rate variability (HRV), are relatively affordable, non-invasive, and cost-effective, making this hallmark easily diagnosable. HRV gains renewed significance within the aging research landscape, offering a tangible link between pathophysiological perturbations and age-related health outcomes.

Navigating the Neuroimmunomodulation Frontier: Pioneering Approaches and Promising Horizons-A Comprehensive Review

The research in neuroimmunomodulation aims to shed light on the complex relationships that exist between the immune and neurological systems and how they affect the human body. This multidisciplinary field focuses on the way immune responses are influenced by brain activity and how neural function is impacted by immunological signaling. This provides important insights into a range of medical disorders. Targeting both brain and immunological pathways, neuroimmunomodulatory approaches are used in clinical pain management to address chronic pain. Pharmacological therapies aim to modulate neuroimmune interactions and reduce inflammation. Furthermore, bioelectronic techniques like vagus nerve stimulation offer non-invasive control of these systems, while neuromodulation techniques like transcranial magnetic stimulation modify immunological and neuronal responses to reduce pain. Within the context of aging, neuroimmunomodulation analyzes the ways in which immunological and neurological alterations brought on by aging contribute to cognitive decline and neurodegenerative illnesses. Restoring neuroimmune homeostasis through strategies shows promise in reducing age-related cognitive decline. Research into mood disorders focuses on how immunological dysregulation relates to illnesses including anxiety and depression. Immune system fluctuations are increasingly recognized for their impact on brain function, leading to novel treatments that target these interactions. This review emphasizes how interdisciplinary cooperation and continuous research are necessary to better understand the complex relationship between the neurological and immune systems.

Is choline deficiency an unrecognized factor in necrotizing enterocolitis of preterm infants?

We undertook this review to determine if it is plausible that choline or phosphatidylcholine (PC) deficiency is a factor in necrotizing enterocolitis (NEC) after two clinical trials found a dramatic and unexpected reduction in NEC in an experimental group provided higher PC compared to a control group. Sources and amounts of choline/PC for preterm infants are compared to the choline status of preterm infants at birth and following conventional nutritional management. The roles of choline/PC in intestinal structure, mucus, mesenteric blood flow, and the cholinergic anti-inflammatory system are summarized. Low choline/PC status is linked to prematurity/immaturity, parenteral and enteral feeding, microbial dysbiosis and hypoxia/ischemia, factors long associated with the risk of developing NEC. We conclude that low choline status exists in preterm infants provided conventional parenteral and enteral nutritional management, and that it is plausible low choline/PC status adversely affects intestinal function to set up the vicious cycle of inflammation, loss of intestinal barrier function and worsening tissue hypoxia that occurs with NEC. In conclusion, this review supports the need for randomized clinical trials to test the hypothesis that additional choline or PC provided parenterally or enterally can reduce the incidence of NEC in preterm infants. IMPACT STATEMENT: Low choline status in preterm infants who are managed by conventional nutrition is plausibly linked to the risk of developing necrotizing enterocolitis.

Diminazene aceturate attenuates systemic inflammation via microbiota gut-5-HT brain-spleen sympathetic axis in male mice

The sympathetic arm of the inflammatory reflex is the efferent pathway through which the central nervous system (CNS) can control peripheral immune responses. Diminazene aceturate (DIZE) is an antiparasitic drug that has been reported to exert protective effects on various experimental models of inflammation. However, the pathways by which DIZE promotes a protective immunomodulatory effects still need to be well established, and no studies demonstrate the capacity of DIZE to modulate a neural reflex to control inflammation. C57BL/6 male mice received intraperitoneal administration of DIZE (2 mg/Kg) followed by lipopolysaccharide (LPS, 5 mg/Kg, i.p.). Endotoxemic animals showed hyperresponsiveness to inflammatory signals, while those treated with DIZE promoted the activation of the inflammatory reflex to attenuate the inflammatory response during endotoxemia. The unilateral cervical vagotomy did not affect the anti-inflammatory effect of DIZE in the spleen and serum. At the same time, splenic denervation attenuated tumor necrosis factor (TNF) synthesis in the spleen and serum. Using broad-spectrum antibiotics for two weeks showed that LPS modulated the microbiota to induce a pro-inflammatory profile in the intestine and reduced the serum concentration of tryptophan and serotonin (5-HT), while DIZE restored serum tryptophan and increased the hypothalamic 5-HT levels. Furthermore, the treatment with 4-Chloro-DL-phenylalanine (pcpa, an inhibitor of 5-HT synthesis) abolished the anti-inflammatory effects of the DIZE in the spleen. Our results indicate that DIZE promotes microbiota modulation to increase central 5-HT levels and activates the efferent sympathetic arm of the inflammatory reflex to control splenic TNF production in endotoxemic mice.

Beta-adrenergic signaling and T-lymphocyte-produced catecholamines are necessary for interleukin 17A synthesis

Background

Post-traumatic stress disorder (PTSD) is a debilitating psychological disorder that also presents with neuroimmune irregularities. Patients display elevated sympathetic tone and are at an increased risk of developing secondary autoimmune diseases. Previously, using a preclinical model of PTSD, we demonstrated that elimination of sympathetic signaling to T-lymphocytes specifically limited their ability to produce pro-inflammatory interleukin 17A (IL-17A); a cytokine implicated in the development of many autoimmune disorders. However, the mechanism linking sympathetic signaling to T-lymphocyte IL-17A production remained unclear.

Methods

Using a modified version of repeated social defeat stress (RSDS) that allows for both males and females, we assessed the impact of adrenergic receptor blockade (genetically and pharmacologically) and catecholamine depletion on T-lymphocyte IL-17A generation. Additionally, we explored the impact of adrenergic signaling and T-lymphocyte-produced catecholamines on both CD4+ and CD8+ T-lymphocytes polarized to IL-17A-producing phenotypes ex vivo.

Results

Only pharmacological inhibition of the beta 1 and 2 adrenergic receptors (β1/2) significantly decreased circulating IL-17A levels after RSDS, but did not impact other pro-inflammatory cytokines (e.g., IL-6, TNF-α, and IL-10). This finding was confirmed using RSDS with both global β1/2 receptor knock-out mice, as well as by adoptively transferring β1/2 knock-out T-lymphocytes into immunodeficient hosts. Furthermore, ex vivo polarized T-lymphocytes produced significantly less IL-17A with the blockade of β1/2 signaling, even in the absence of exogenous sympathetic neurotransmitter supplementation, which suggested T-lymphocyte-produced catecholamines may be involved in IL-17A production. Indeed, pharmacological depletion of catecholamines both in vivo and ex vivo abrogated T-lymphocyte IL-17A production demonstrating the importance of immune-generated neurotransmission in pro-inflammatory cytokine generation.

Conclusions

Our data depict a novel role for β1/2 adrenergic receptors and autologous catecholamine signaling during T-lymphocyte IL-17A production. These findings provide a new target for pharmacological therapy in both psychiatric and autoimmune diseases associated with IL-17A-related pathology.

T cells at the interface of neuroimmune communication

The immune system protects the host from infection and works to heal damaged tissue after infection or injury. There is increasing evidence that the immune system and the nervous system work in concert to achieve these goals. The sensory nervous system senses injury, infection, and inflammation, which results in a direct pain signal. Direct activation of peripheral sensory nerves can drive an inflammatory response in the skin. Immune cells express receptors for numerous transmitters released from sensory and autonomic nerves, which allows the nervous system to communicate directly with the immune system. This communication is bidirectional because immune cells can also produce neurotransmitters. Both innate and adaptive immune cells respond to neuronal signaling, but T cells appear to be at the helm of neuroimmune communication.

Molecular cell types as functional units of the efferent vagus nerve

The vagus nerve vitally connects the brain and body to coordinate digestive, cardiorespiratory, and immune functions. Its efferent neurons, which project their axons from the brainstem to the viscera, are thought to comprise "functional units" - neuron populations dedicated to the control of specific vagal reflexes or organ functions. Previous research indicates that these functional units differ from one another anatomically, neurochemically, and physiologically but have yet to define their identity in an experimentally tractable way. However, recent work with genetic technology and single-cell genomics suggests that genetically distinct subtypes of neurons may be the functional units of the efferent vagus. Here we review how these approaches are revealing the organizational principles of the efferent vagus in unprecedented detail.

Neuromorphic electro-stimulation based on atomically thin semiconductor for damage-free inflammation inhibition

Inflammation, caused by accumulation of inflammatory cytokines from immunocytes, is prevalent in a variety of diseases. Electro-stimulation emerges as a promising candidate for inflammatory inhibition. Although electroacupuncture is free from surgical injury, it faces the challenges of imprecise pathways/current spikes, and insufficiently defined mechanisms, while non-optimal pathway or spike would require high current amplitude, which makes electro-stimulation usually accompanied by damage and complications. Here, we propose a neuromorphic electro-stimulation based on atomically thin semiconductor floating-gate memory interdigital circuit. Direct stimulation is achieved by wrapping sympathetic chain with flexible electrodes and floating-gate memory are programmable to fire bionic spikes, thus minimizing nerve damage. A substantial decrease (73.5%) in inflammatory cytokine IL-6 occurred, which also enabled better efficacy than commercial stimulator at record-low currents with damage-free to sympathetic neurons. Additionally, using transgenic mice, the anti-inflammation effect is determined by β2 adrenergic signaling from myeloid cell lineage (monocytes/macrophages and granulocytes).

Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

As one of most common and severe mental disorders, major depressive disorder (MDD) significantly increases the risks of premature death and other medical conditions for patients. Neuroinflammation is the abnormal immune response in the brain, and its correlation with MDD is receiving increasing attention. Neuroinflammation has been reported to be involved in MDD through distinct neurobiological mechanisms, among which the dysregulation of neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC) is receiving increasing attention. The DG of the hippocampus is one of two niches for neurogenesis in the adult mammalian brain, and neurotrophic factors are fundamental regulators of this neurogenesis process. The reported cell types involved in mediating neuroinflammation include microglia, astrocytes, oligodendrocytes, meningeal leukocytes, and peripheral immune cells which selectively penetrate the blood-brain barrier and infiltrate into inflammatory regions. This review summarizes the functions of the hippocampus affected by neuroinflammation during MDD progression and the corresponding influences on the memory of MDD patients and model animals.

Nicotinic Acetylcholine Receptor Dysfunction in Addiction and in Some Neurodegenerative and Neuropsychiatric Diseases

The cholinergic system plays an essential role in brain development, physiology, and pathophysiology. Herein, we review how specific alterations in this system, through genetic mutations or abnormal receptor function, can lead to aberrant neural circuitry that triggers disease. The review focuses on the nicotinic acetylcholine receptor (nAChR) and its role in addiction and in neurodegenerative and neuropsychiatric diseases and epilepsy. Cholinergic dysfunction is associated with inflammatory processes mainly through the involvement of α7 nAChRs expressed in brain and in peripheral immune cells. Evidence suggests that these neuroinflammatory processes trigger and aggravate pathological states. We discuss the preclinical evidence demonstrating the therapeutic potential of nAChR ligands in Alzheimer disease, Parkinson disease, schizophrenia spectrum disorders, and in autosomal dominant sleep-related hypermotor epilepsy. PubMed and Google Scholar bibliographic databases were searched with the keywords indicated below.