Sympathetic nerve distribution in human lymph nodes

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.

Effect of transcutaneous neuromodulation on normalization of dermal body temperature and pain in a tender scar in the presence of low back pain: An update and case report

Low back pain affects over 20% of individuals during their lifetime, and in some patients, it may be associated with scar tissue formation after surgery. Small-fiber neuropathy and scar tissue dysfunction can lead to localized pain by affecting signals to the thalamus. Transcutaneous neuromodulation using Tape with Magnetic Particles shows promise in relieving perceived pain, modulating vascularization and the autonomic nervous system, and reducing dermal temperature. In the present case, a 24-year-old woman with L5-S1 disk herniation experienced low back pain and leg pressure. The surgical intervention provided temporary relief, but scar restrictions caused pain recurrence. Tape with Magnetic Particles application initially induced scar hypothermia and pressure tolerance during posteroanterior tests on lumbar spinous processes increased, reducing pain perception for at least 12 h. Transcutaneous neuromodulation with Tape with Magnetic Particles modulated dermal temperature immediately and for 12 h, reducing perceived pain and sustaining improvement thereafter. This highlights the potential of Tape with Magnetic Particles in managing chronic low back pain associated with scar tissue.

Dominant mechanism in spinal cord injury-induced immunodeficiency syndrome (SCI-IDS): sympathetic hyperreflexia

Clinical studies have shown that individuals with spinal cord injury (SCI) are particularly susceptible to infectious diseases, resulting in a syndrome called SCI-induced immunodeficiency syndrome (SCI-IDS), which is the leading cause of death after SCI. It is believed that SCI-IDS is associated with exaggerated activation of sympathetic preganglionic neurons (SPNs). After SCI, disruption of bulbospinal projections from the medulla oblongata C1 neurons to the SPNs results in the loss of sympathetic inhibitory modulation from the brain and brainstem and the occurrence of abnormally high levels of spinal sympathetic reflexes (SSR), named sympathetic hyperreflexia. As the post-injury survival time lengthens, mass recruitment and anomalous sprouting of excitatory interneurons within the spinal cord result in increased SSR excitability, resulting in an excess sympathetic output that disrupts the immune response. Therefore, we first analyze the structural underpinnings of the spinal cord-sympathetic nervous system-immune system after SCI, then demonstrate the progress in highlighting mechanisms of SCI-IDS focusing on norepinephrine (NE)/Beta 2-adrenergic receptor (β2-AR) signal pathways, and summarize recent preclinical studies examining potential means such as regulating SSR and inhibiting β2-AR signal pathways to improve immune function after SCI. Finally, we present research perspectives such as to promote the effective regeneration of C1 neurons to rebuild the connection of C1 neurons with SPNs, to regulate excitable or inhibitory interneurons, and specifically to target β2-AR signal pathways to re-establish neuroimmune balance. These will help us design effective strategies to reverse post-SCI sympathetic hyperreflexia and improve the overall quality of life for individuals with SCI.

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.

Sepsis-Induced Inhibition of Contractile Function of Lymphatic Nodes

Inflammation accompanies most pathological processes, while the lymphatic system takes part in both the development and resolution of inflammation. We studied the contractile function of rat lymph nodes after cecal ligation and puncture (CLP). In 24 h after CLP, the mesenteric lymph nodes were removed and placed in the myograph chamber. After CLP, the lymph nodes showed lower tension than lymph nodes from sham-operated animals (control). The expression of inducible NO synthase, cyclooxygenase-2, and cystathionine-γ-lyase was observed in the lymph nodes of CLP rats. NO, prostaglandins, and H2S formed during inflammation inhibited contractile activity of smooth muscle cells in the capsule of the lymph nodes, which manifested itself in inhibition of phase contractions and a decrease in the tone of their capsule.

Distribution of Contractile Structures in a Mouse and Human Lymph Node Associated with Lymph Flow

Lymph nodes have contractile structures, but their distribution in a lymph node has been less considered in terms of facilitation of lymph flow. Axillary, inguinal, and mesenteric lymph nodes were collected from mice and human cadavers, and their sections were immunostained for alpha-smooth muscle actin (αSMA) and high molecular weight caldesmon (H-caldesmon). The αSMA-positive cells were localized in the capsule beneath the ceiling epithelium on the afferent side in both mice and humans. We found an additional layer of the αSMA-positive cells in the human lymph node, surrounding the inner layer perpendicularly. H-caldesmon was expressed only in these cells of the outer layer. In some human lymph nodes highly containing fat tissue in the medulla, the capsule disappeared on the efferent side, resulting in a disrupted sinusoidal lymph pathway. These findings suggest that human lymph nodes have additional smooth muscles in the outer region of the capsule to facilitate lymph flow. The αSMA-positive cells in the outer and inner layers of human lymph nodes probably have different functions in contraction. The presence of lipomatosis in a human lymph node will reduce its contribution to the lymph flow.

The postnatal development of the compartments in human lymph nodes up to 15 years of age

The postnatal development of normal human lymph nodes (LN) is largely unknown but is of relevance for intranodal desensitization and for comparison to lymphoma. Superficial inguinal lymphoid (LN) of 25 children (newborn up to 14 years) were studied by routine histology and immunohistology for T and B lymphocytes. The LN were obtained from the legal medicine department at necropsy. The cortex and medulla were identifiable in LN of children of less than 1 month of age. Later high endothelial venules as typical structures for the T cell area are present. Secondary follicles were obvious from 3 months of age onwards in lymph nodes of adolescents also the histology of the LN was similar to adults. The structural elements for an intranodal desensitization are given in human children. The normal development of LN structure is essential to identify pathology like lymphoma in children.

Bidirectional crosstalk between the peripheral nervous system and lymphoid tissues/organs

The central nervous system (CNS) influences the immune system generally by regulating the systemic concentration of humoral substances (e.g., cortisol and epinephrine), whereas the peripheral nervous system (PNS) communicates specifically with the immune system according to local interactions/connections. An imbalance between the components of the PNS might contribute to pathogenesis and the further development of certain diseases. In this review, we have explored the "thread" (hardwiring) of the connections between the immune system (e.g., primary/secondary/tertiary lymphoid tissues/organs) and PNS (e.g., sensory, sympathetic, parasympathetic, and enteric nervous systems (ENS)) in health and disease in vitro and in vivo. Neuroimmune cell units provide an anatomical and physiological basis for bidirectional crosstalk between the PNS and the immune system in peripheral tissues, including lymphoid tissues and organs. These neuroimmune interactions/modulation studies might greatly contribute to a better understanding of the mechanisms through which the PNS possibly affects cellular and humoral-mediated immune responses or vice versa in health and diseases. Physical, chemical, pharmacological, and other manipulations of these neuroimmune interactions should bring about the development of practical therapeutic applications for certain neurological, neuroimmunological, infectious, inflammatory, and immunological disorders/diseases.

Submandibular nodal schwannoma: where did it come from?

SummarySchwannoma, a type of benign neurological tumour arising from Schwann cells, is commonly seen in the head and neck region. However, the incidence of cervical lymph node schwannoma is extremely rare, with only two cases reported in the literature. Schwannomatosis is a disease characterised by a constellation of multiple schwannomas seen in a patient, guided by at least one confirmational histological diagnosis. This is a case of a painless progressively enlarging submandibular swelling which is confirmed as a schwannoma based on histology. The patient is also diagnosed with schwannomatosis as the patient has multiple neurological tumours. Nodal schwannoma has a good prognosis and no documentation of recurrence in the literature. It may arise from sympathetic nerves located within the lymph node.

Neuro-immune interactions and immuno-oncology

The nervous system is an important component of the tumor microenvironment (TME), driving tumorigenesis and tumor progression. Neuronal cues (e.g., neurotransmitters and neuropeptides) in the TME cause phenotypic changes in immune cells, such as increased exhaustion and inhibition of effector cells, which promote immune evasion and cancer progression. Two types of immune regulation by tumor-associated nerves are discussed in this review: regulation via neuronal stimuli (i.e., by neural transmission) and checkpoint-mediated neuronal immune regulation. The latter occurs via the expression of immune checkpoints on the membranes of intratumoral nerves and glial cells. Here, we summarize novel findings regarding the neuroimmune circuits in the tumor milieu, while emphasizing the potential targets of new and affordable anticancer therapeutic approaches.

New tools for immunologists: models of lymph node function from cells to tissues

The lymph node is a highly structured organ that mediates the body's adaptive immune response to antigens and other foreign particles. Central to its function is the distinct spatial assortment of lymphocytes and stromal cells, as well as chemokines that drive the signaling cascades which underpin immune responses. Investigations of lymph node biology were historically explored in vivo in animal models, using technologies that were breakthroughs in their time such as immunofluorescence with monoclonal antibodies, genetic reporters, in vivo two-photon imaging, and, more recently spatial biology techniques. However, new approaches are needed to enable tests of cell behavior and spatiotemporal dynamics under well controlled experimental perturbation, particularly for human immunity. This review presents a suite of technologies, comprising in vitro, ex vivo and in silico models, developed to study the lymph node or its components. We discuss the use of these tools to model cell behaviors in increasing order of complexity, from cell motility, to cell-cell interactions, to organ-level functions such as vaccination. Next, we identify current challenges regarding cell sourcing and culture, real time measurements of lymph node behavior in vivo and tool development for analysis and control of engineered cultures. Finally, we propose new research directions and offer our perspective on the future of this rapidly growing field. We anticipate that this review will be especially beneficial to immunologists looking to expand their toolkit for probing lymph node structure and function.

Visualization of the carotid body in situ in fixed human carotid bifurcations using a xylene-based tissue clearing method

The anatomy of the carotid body (CB) and its nerve supply are important, because it is a potential therapeutic target for treatment of various clinical conditions. Visualization of the CB in situ in fixed human anatomical specimens is hampered by obscuring adipose and connective tissues. We developed a tissue clearing method to optimize identification of the CB. We used single sided carotid bifurcations of six human cadavers fixed long term. Visualization of the CB was accomplished by clearing tissue with xylene. Under incident light, carotid bifurcations exhibited a less transparent, darker colored CB; hematoxylin and eosin stained paraffin sections confirmed its identity. Our visualization of the CB in situ in human carotid bifurcations fixed long term enabled targeted resection and subsequent topographic and morphometric measurements of the CB. Our procedure does not interfere with immunohistochemical staining of sections prepared from such specimens.

Neuro-immune-endocrine mechanisms with poor adherence to aromatase inhibitor therapy in breast cancer

As the most commonly used endocrine therapy regimen for patients with hormone receptor-positive (HR+) breast cancer (BC) at present, aromatase inhibitors (AIs) reduce the risk of localized and distant recurrence, contralateral BC and secondary cancer, and prolong disease-free survival. Clinical data show that poor adherence during AI treatment is mainly attributed to muscle and joint pain, fatigue, anxiety, depression and sleep disturbances during treatment. The rapid decline of estrogen caused by AIs in a short period of time enhances sympathetic activity, activates T cells in the body, produces inflammatory factors such as tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and interleukin (IL)-17A, and promotes the occurrence of inflammation and bone loss. This article reviewed the mechanism of poor dependence on AIs in BC patients from the neuro-immuno-endocrine (NIE) perspective and provided clues for clinical intervention against poor adherence.

Compression therapy, autonomic nervous system, and heart rate variability: A narrative review and our preliminary personal experience

Aims

To highlight the relationship among compression therapy (CT), the autonomic nervous system (ANS) (parasympathetic and sympathetic system), and the heart rate variability (HRV) analysis.

Background

Beyond the typical analgesic and anti-inflammatory effects of CT in patients affected by venous and/or lymphatic diseases, some literature about CT influence on wellbeing has been published as well. More specifically, CT influence on the ANS has been elucidated mostly through HRV application, providing useful quali-quantitative data for scientific and clinical purposes.

Material and Methods

A literature search was performed through several web-based search engines to investigate the available evidence concerning the possible influence of CT on the ANS and on psychoneuroendocrineimmunology. Moreover, we examined literature data regarding HRV use in the assessment of CT. Lastly, a preliminary cross-over study was performed on 10 patients affected by phlebolymphedema of the lower limbs, undergoing CT with 18–21 mmHg stockings for 10 h and investigated by means of HRV.

Results

A CT-based increase of the anti-inflammatory activity of the parasympathetic (vagal) system has been elucidated in most scientific literature. Similarly, CT application has generally resulted in an improvement of HRV, which indicates a beneficial influence on the ANS. In our preliminary experience with compression stockings and HRV, two parasympathetic-based parameters improved by 22.8% and 68.0% after 10 h, whereas they decreased in the same subjects without stockings by 2.7% and 8.2%, during normal breathing. The remaining HRV parameters did not show relevant variations, especially during diaphragmatic breathing.

Conclusions

From literature data and based on our very preliminary experience, it is possible to deduce that CT exerts different effects on the psychobiological parameters of the individual, overall improving HRV and parasympathetic activity. Incorporating both HRV/ANS assessment in phlebolymphology and the beneficial neural action of CT in health care may represent viable options in the future biomedical science.

Control of lymph node activity by direct local innervation

The nervous system detects environmental and internal stimuli and relays this information to immune cells via neurotransmitters and neuropeptides. This is essential to respond appropriately to immunogenic threats and to support system homeostasis. Lymph nodes (LNs) act as sentinels where adaptive immune responses are generated. They are richly innervated by peripheral sympathetic and sensory nerves, which are responsible for the local secretion of neurotransmitters by sympathetic fibers, such as norepinephrine, and neuropeptides by sensory fibers, including calcitonin gene-related peptide (CGRP) and substance P. Additionally, time-of-day-dependent oscillations in nerve activity are associated with differential immune responses, suggesting a potential role for neuroimmune interactions in coordinating immunity in a circadian fashion. Here, we discuss how LN activity is controlled by local innervation.

Neural control of immune cell trafficking

Leukocyte trafficking between blood and tissues is an essential function of the immune system that facilitates humoral and cellular immune responses. Within tissues, leukocytes perform surveillance and effector functions via cell motility and migration toward sites of tissue damage, infection, or inflammation. Neurotransmitters that are produced by the nervous system influence leukocyte trafficking around the body and the interstitial migration of immune cells in tissues. Neural regulation of leukocyte dynamics is influenced by circadian rhythms and altered by stress and disease. This review examines current knowledge of neuro–immune interactions that regulate leukocyte migration and consequences for protective immunity against infections and cancer.

The Direct Effect of Magnetic Tape® on Pain and Lower-Extremity Blood Flow in Subjects with Low-Back Pain: A Randomized Clinical Trial

Low-back pain has a high impact on the world population, and solutions are in demand. The behavior of specific physiological processes has been modified using magnetic fields, whether for pain relief, bone consolidation, or improvement of vascularization. The use of tape with magnetic properties could help in these cases. A double-blind randomized clinical trial was designed to use Magnetic Tape^® versus placebo Kinesio tape. Blood flow variables were evaluated using pulsed power Doppler ultrasound. Resistance index, pulsatility index, systolic velocity, and diastolic velocity were measured. The pressure pain threshold was measured using algometry in 22 subjects. The results reveal significant differences between the groups for the pulsation index variable (8.06 [5.16, 20.16] in Magnetic Tape^® versus 5.50 [4.56, 6.64] in Kinesio tape) and lower (0.98 [0.92, 1.02] for Magnetic Tape^® versus 0.99 [0.95, 1.01] for Kinesio tape) in the resistance index variable. The pressure pain threshold variable presented significant differences at multiple levels. The application of Magnetic Tape^® causes immediate effects on blood flow and pain and could be a technique of choice for pain modulation. Further studies would be necessary.

Adipose Tissue and Biological Factors. Possible Link between Lymphatic System Dysfunction and Obesity

The World Health Organization (WHO) has recognised obesity as one of the top ten threats to human health. Obesity is not only a state of abnormally increased adipose tissue in the body, but also of an increased release of biologically active metabolites. Moreover, obesity predisposes the development of metabolic syndrome and increases the incidence of type 2 diabetes (T2DM), increases the risk of developing insulin resistance, atherosclerosis, ischemic heart disease, polycystic ovary syndrome, hypertension and cancer. The lymphatic system is a one-directional network of thin-walled capillaries and larger vessels covered by a continuous layer of endothelial cells that provides a unidirectional conduit to return filtered arterial and tissue metabolites towards the venous circulation. Recent studies have shown that obesity can markedly impair lymphatic function. Conversely, dysfunction in the lymphatic system may also be involved in the pathogenesis of obesity. This review highlights the important findings regarding obesity related to lymphatic system dysfunction, including clinical implications and experimental studies. Moreover, we present the role of biological factors in the pathophysiology of the lymphatic system and we propose the possibility of a therapy supporting the function of the lymphatic system in the course of obesity.