Urinary bladder, cystitis and nerve/urothelial interactions

Real-Time Void Spot Assay

Normal voiding behavior is the result of the coordinated function of the bladder, the urethra, and the urethral sphincters under the proper control of the nervous system. To study voluntary voiding behavior in mouse models, researchers have developed the void spot assay (VSA), a method that measures the number and area of urine spots deposited on a filter paper lining the floor of an animal's cage. Although technically simple and inexpensive, this assay has limitations when used as an end-point assay, including a lack of temporal resolution of voiding events and difficulties quantifying overlapping urine spots. To overcome these limitations, we developed a video-monitored VSA, which we call real-time VSA (RT-VSA), and which allows us to determine voiding frequency, assess voided volume and voiding patterns, and make measurements over 6 h time windows during both the dark and light phases of the day. The method described in this report can be applied to a wide variety of mouse-based studies that explore the physiological and neurobehavioral aspects of voluntary micturition in health and disease states.

Expression of Transgenes in Native Bladder Urothelium using Adenovirus-Mediated Transduction

In addition to forming a high-resistance barrier, the urothelium lining the renal pelvis, ureters, bladder, and proximal urethra is hypothesized to sense and transmit information about its environment to the underlying tissues, promoting voiding function and behavior. Disruption of the urothelial barrier, or its sensory/transducer function, can lead to disease. Studying these complex events is hampered by lack of simple strategies to alter gene and protein expression in the urothelium. Methods are described here that allow investigators to generate large amounts of high-titer adenovirus, which can then be used to transduce rodent urothelium with high efficiency, and in a relatively straightforward manner. Both cDNAs and small interfering RNAs can be expressed using adenoviral transduction, and the impact of transgene expression on urothelial function can be assessed 12 h to several days later. These methods have broad applicability to studies of normal and abnormal urothelial biology using mouse or rat animal models.

Gene Expression-Based Functional Differences between the Bladder Body and Trigonal Urothelium in Adolescent Female Patients with Micturition Dysfunction

The aim of this study is to determine the molecular differences between the urothelial transcriptomes of the bladder body and trigone. The transcriptomes of the bladder body and trigonal epithelia were analyzed by massive sequencing of total epithelial RNA. The profiles of urothelial and urinal microbiomes were assessed by amplicon sequencing of bacterial 16S rRNA genes in 17 adolescent females with pain and micturition dysfunction and control female subjects. The RNA sequencing identified 10,261 differentially expressed genes (DEGs) in the urothelia of the bladder body and trigone, with the top 1000 DEGs at these locations annotated to 36 and 77 of the Reactome-related pathways in the bladder body and trigone, respectively. These pathways represented 11 categories enriched in the bladder body urothelium, including extracellular matrix organization, the neuronal system, and 15 categories enriched in the trigonal epithelium, including RHO GTPase effectors, cornified envelope formation, and neutrophil degranulation. Five bacterial taxa in urine differed significantly in patients and healthy adolescent controls. The evaluation of their transcriptomes indicated that the bladder body and trigonal urothelia were functionally different tissues. The molecular differences between the body and trigonal urothelia responsible for clinical symptoms in adolescents with bladder pain syndrome/interstitial cystitis remain unclear.

Flavonoid Nobiletin Attenuates Cyclophosphamide-Induced Cystitis in Mice through Mechanisms That Involve Inhibition of IL-1β Induced Connexin 43 Upregulation and Gap Junction Communication in Urothelial Cells

Bladder inflammatory diseases cause various urinary symptoms, such as urinary frequency and painful urination, that impair quality of life. In this study, we used a mouse model of cyclophosphamide (CYP)-induced bladder inflammation and immortalized human urothelial (TRT-HU1) cells to explore the preventive potential of nobiletin (NOB), a polymethoxylated flavone enriched in citrus fruit peel, and investigate its mechanism of action in the bladder. Prophylaxis with PMF90 (60% NOB) attenuated the development of bladder inflammation and urinary symptoms in CYP-treated mice. PMF90 also reduced the upregulation of connexin 43 (Cx43), a major component of gap junction channels, in the bladder mucosa of CYP-treated mice. Stimulation of TRT-HU1 cells with the pro-inflammatory cytokine IL-1β increased Cx43 mRNA and protein expression and enhanced gap junction coupling-responses that were prevented by pre-treatment with NOB. In urothelium-specific Cx43 knockout (uCx43KO) mice, macroscopic signs of bladder inflammation and changes in voiding behavior induced by CYP treatment were significantly attenuated when compared to controls. These findings indicate the participation of urothelial Cx43 in the development of bladder inflammation and urinary symptoms in CYP-treated mice and provide pre-clinical evidence for the preventive potential of NOB through its anti-inflammatory effects on IL-1β signaling and urothelial Cx43 expression.

Emerging molecular mechanisms and genetic targets for developing novel therapeutic strategies for treating bladder diseases

Bladder diseases affect millions of patients worldwide and compromise their quality of life with a substantial economic impact. The not fully understood aetiologies of bladder diseases limit the current diagnosis and therapeutic options to primarily symptomatic treatment. In addition, bladder targeted drug delivery is challenging due to its unique anatomical features and its natural physiological function of urine storage and frequent voiding. Therefore, current treatment options often fail to provide a highly effective, precisely targeted and long-lasting treatment. With the growing maturity of gene therapy, comprehensive studies are needed to provide a better understanding of the molecular mechanisms underpinning bladder diseases and help to identify novel gene therapeutic targets and biomarkers for treating bladder diseases. In this review, molecular mechanisms involved in pathology of bladder cancer, interstitial cystitis and overactive bladder syndrome are reviewed, with focus on establishing potential novel treatment options. Proposed novel therapies, including gene therapy combined with nanotechnology, localised drug delivery by nanoparticles, and probiotics, are discussed in regard to their safety profiles, efficacy, treatment lenght, precise targeting, and in comparison to conventional treatment methods.

The effect of intravesical cocktail therapy combined with low-dose amitriptyline on primary bladder pain syndrome

INTRODUCTION AND HYPOTHESIS

We compared the effectiveness of intravesical combination treatment and intravesical treatment plus low-dose amitriptyline in patients with primary bladder pain syndrome (PBPS).

METHODS

A total of 53 patients were included in the study. Demographic data, voiding frequency, nocturia, visual analog scale (VAS) scores, validated O'Leary-Sant IC Symptom Index (ICSI), and IC Problem Index (ICPI) scores and scores on the Short Form-36 (SF-36) questionnaire were collected from the patients at the beginning of the treatment, and at the 6th week and 6th month of the treatment. The patients were divided into two groups. Group 1 received intravesical treatment for 6 weeks. Group 2 received intravesical treatment plus amitriptyline at a dosage of 10 mg/day.

RESULTS

The frequencies of voiding and VAS scores were significantly improved in groups 1 and 2 at the 6th week compared with pretreatment (in group 1 p < 0.001, p < 0.001, and in group 2 p < 0.001, p < 0.001 respectively). The median ICSI and ICPI scores also significantly decreased in groups 1 and 2 (in group 1 p < 0.001, p < 0.001, and in group 2 p < 0.001, p < 0.001 respectively). Scores on the dimensions of the SF-36 questionnaire were significantly improved in both groups. There was no significant change in terms of VAS, nocturia, ICSI or ICPI scores when comparing the 6th week and 6th month results in groups 1 and 2 (all p > 0.05). Only role functioning/emotional achieved a significant improvement in group 2 (p = 0.007).

CONCLUSIONS

Intravesical combination therapies are effective in PBPS treatment. Adding low-dose amitriptyline to intravesical therapy in patients with PBPS improves emotional status.

Feline Idiopathic Cystitis: Pathogenesis, Histopathology and Comparative Potential

Bladder pain syndrome (BPS) is a debilitating disease in humans, particularly women, with patients experiencing chronic, intractable, lower urinary and pelvic pain. Although rodent models have been used, feline idiopathic cystitis (FIC) is a naturally occurring bladder disease of cats that is frequently considered to be the preferred model for BPS. Histologically, FIC is most similar to the non-Hunner BPS subtype. Histology is unnecessary for the clinical diagnosis of FIC but is of great value in elucidating the pathogenesis of this disease so that prevention and therapeutic interventions can be optimized. Further study of the histological features of FIC and BPS is required to determine the significance of Von Brunn's nests, which are invaginations of hyperplastic urothelium that have been associated with irritative bladder stimuli in animals and have been observed in FIC. We review the possible pathogenesis, histopathological similarities and differences between FIC and BPS, and highlight the potential of FIC as a model of BPS.

Overactive Bladder Symptoms in Patients with Fibromyalgia: A Systematic Case-Controlled Study

BACKGROUND

A recent survey reported an association between fibromyalgia and overactive bladder.

OBJECTIVE

To carry out the first systematic case-controlled study to compare the level of overactive bladder symptoms in a group of fibromyalgia patients and a group of matched controls.

METHODS

The symptom-bother OAB-q8 questionnaire and Revised Fibromyalgia Impact Questionnaire (FIQR) were administered to 27 patients who fulfilled the revised diagnostic criteria for fibromyalgia of the American College of Rheumatology and to 26 healthy controls who had no history of suffering from fibromyalgia or any other rheumatological or neurological illness.

RESULTS

The groups were matched in respect of age, sex and ethnicity. None of the 53 subjects was taking medication, which might cause urinary urgency, none was suffering from, or had recently suffered from, a urinary tract infection and none had undergone a previous operative procedure on the lower urinary tract. Twenty-five (93%) patients had evidence of an overactive bladder during the previous four weeks, compared with five (19%) of the control group (p < 0.001). In terms of symptom severity, the mean (standard error) OAB-q8 score was 24.4 (1.5) in the fibromyalgia patients and 10.8 (4.5) in the controls (p < 0.001). Furthermore, the total OAB-q8 and FIQR scores were positively correlated (rs = 0.727, p < 0.001).

CONCLUSION

This systematic controlled study confirms that fibromyalgia is associated with overactive bladder symptoms. The relatively high prevalence of 93% indicates that overactive bladder is an important urological association of fibromyalgia and should be routinely assessed in these patients.

The Urothelium: Life in a Liquid Environment

The urothelium, which lines the renal pelvis, ureters, urinary bladder, and proximal urethra, forms a high-resistance but adaptable barrier that surveils its mechanochemical environment and communicates changes to underlying tissues including afferent nerve fibers and the smooth muscle. The goal of this review is to summarize new insights into urothelial biology and function that have occurred in the past decade. After familiarizing the reader with key aspects of urothelial histology, we describe new insights into urothelial development and regeneration. This is followed by an extended discussion of urothelial barrier function, including information about the roles of the glycocalyx, ion and water transport, tight junctions, and the cellular and tissue shape changes and other adaptations that accompany expansion and contraction of the lower urinary tract. We also explore evidence that the urothelium can alter the water and solute composition of urine during normal physiology and in response to overdistension. We complete the review by providing an overview of our current knowledge about the urothelial environment, discussing the sensor and transducer functions of the urothelium, exploring the role of circadian rhythms in urothelial gene expression, and describing novel research tools that are likely to further advance our understanding of urothelial biology.

Influence of Circadian Disruption Associated With Artificial Light at Night on Micturition Patterns in Shift Workers

Shift workers often experience problems associated with circadian disruption associated with artificial light at night and nocturia is commonly noted in night-shift workers. Nocturia associated with circadian disruption is due to increased urine production of the kidney and decreased storage function of the bladder. A recent discovery of peripheral clock genes in the bladder and their role in contractile property of the bladder support that micturition is closely related to the circadian rhythm. Moreover, there are clinical studies showed that shift workers more often experienced nocturia due to circadian disruption. However, comparing with other health problems, concerns on nocturia and voiding dysfunction associated with circadian disruption are insufficient. Therefore, further studies about voiding dysfunction associated with the circadian disruption in shift workers are necessary.

Risk Factors for Interstitial Cystitis in the General Population and in Individuals With Depression

PURPOSE

To identify risk factors for interstitial cystitis (IC), a chronic bladder disorder that may have a significant detrimental impact on quality of life, in the general population and in individuals with depression.

METHODS

This was a comparative study using a US claims database. Adults who had records of a visit to the health system in 2010 or later were included. The outcome was the development of IC within 2 years after the index date. The index date for the general population was the first outpatient visit, and for individuals with depression, it was the date of the diagnosis of depression. IC was defined using the concepts of ulcerative and IC. We included all medical conditions present any time prior to the index visit as potential risk factors.

RESULTS

The incidence of IC was higher in individuals with depression than in the general population. Of the 3,973,000 subjects from the general population, 2,293 (0.06%) developed IC within 2 years. Of the 249,200 individuals with depression, 320 (0.13%) developed IC. The characteristics of the individuals who developed IC were similar in both populations. Those who developed IC were slightly older, more likely to be women, and had more chronic pain conditions, malaise, and inflammatory disorders than patients without IC. In the general population, subjects who developed IC were more likely to have mood disorders, anxiety, and hypothyroidism.

CONCLUSION

The incidence of IC was higher in individuals with depression. Subjects who developed IC had more chronic pain conditions, depression, malaise, and inflammatory disorders.

Stress-induced autonomic dysregulation of mitochondrial function in the rat urothelium

AIM

Chronic stress exacerbates the symptoms of most pain disorders including interstitial cystitis/bladder pain syndrome (IC/BPS). Abnormalities in urothelial cells (UTC) occur in this debilitating bladder condition. The sequence of events that might link stress (presumably through increased sympathetic nervous system-SNS activity) to urothelial dysfunction are unknown. Since autonomic dysregulation, mitochondrial dysfunction, and oxidative stress all occur in chronic pain, we investigated whether chronic psychological stress initiated a cascade linking these three dysfunctions.

METHODS

Adult female Wistar Kyoto rats were exposed to 10 days of water avoidance stress (WAS). Bladders were then harvested for Western blot and single cell imaging in UTC cultures.

RESULTS

UTC from WAS rats exhibited depolarized mitochondria membrane potential (Ψm ∼30% more depolarized compared to control), activated AMPK and altered UT mitochondria bioenergetics. Expression of the fusion protein mitofusion-2 (MFN-2) was upregulated in the mucosa, suggesting mitochondrial structural changes consistent with altered cellular metabolism. Intracellular calcium levels were elevated in cultured WAS UTC, consistent with impaired cellular function. Stimulation of cultured UTC with alpha-adrenergic (α-AR) receptor agonists increased reactive oxidative species (ROS) production, suggesting a direct action of SNS activity on UTC. Treatment of rats with guanethidine to block SNS activity prevented most of WAS-induced changes.

CONCLUSIONS

Chronic stress results in persistent sympathetically mediated effects that alter UTC mitochondrial function. This may impact the urothelial barrier and signaling, which contributes to bladder dysfunction and pain. This is the first demonstration, to our knowledge, of a potential autonomic mechanism directly linking stress to mitochondrial dysfunction.

Urothelial Senescence in the Pathophysiology of Diabetic Bladder Dysfunction-A Novel Hypothesis

Diabetic bladder dysfunction (DBD) is a well-recognized and common symptom affecting up to 50% of all diabetic patients. DBD has a broad range of clinical presentations ranging from overactive to underactive bladder symptoms that develops in middle-aged to elderly patients with long standing and poorly controlled diabetes. Low efficacy of current therapeutics and lifestyle interventions combined with high national healthcare costs highlight the need for more research into bladder dysfunction pathophysiology and novel treatment options. Cellular senescence is an age-related physiologic process in which cells undergo irreversible growth arrest induced by replicative exhaustion and damaging insults. While controlled senescence negatively regulates cell proliferation and promotes tissue regeneration, uncontrolled senescence is known to result in tissue dysfunction through enhanced secretion of inflammatory factors. This review presents previous scientific findings and current hypotheses that characterize diabetic bladder dysfunction. Further, we propose the novel hypothesis that cellular senescence within the urothelial layer of the bladder contributes to the pro-inflammatory/pro-oxidant environment and symptoms of diabetic bladder dysfunction. Our results show increased cellular senescence in the urothelial layer of the bladder; however, whether this phenomenon is the cause or effect of DBD is unknown. The urothelial layer of the bladder is made up of transitional epithelia specialized to contract and expand with demand and plays an active role in transmission by modulating afferent activity. Transition from normal functioning urothelial cells to secretory senescence cells would not only disrupt the barrier function of this layer but may result in altered signaling and sensation of bladder fullness; dysfunction of this layer is known to result in symptoms of frequency and urgency. Future DBD therapeutics may benefit from targeting and preventing early transition of urothelial cells to senescent cells.

Symptomatic overlap in overactive bladder and interstitial cystitis/bladder pain syndrome: development of a new algorithm

OBJECTIVES

To address challenges in the diagnosis and classification of storage lower urinary tract symptoms (LUTS), we sought to define the fundamental features of overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome (IC/BPS), two conditions with considerable symptomatic overlap. Through retrospective comparison of self-reported symptoms in women with a range of clinical presentations and symptom severities, we have attempted to refine the diagnostic features of OAB and IC/BPS and to develop a novel clinical nomogram to improve patient screening and classification.

MATERIALS AND METHODS

We performed a univariate analysis comparing responses to the female Genitourinary Pain Index (fGUPI), the OAB Questionnaire and O'Leary-Sant Indices (the Interstitial Cystitis Symptom Index and Interstitial Cystitis Problem Index) in an initial cohort of 50 patients with OAB, patients with IC/BPS and control subjects. Only eight questions differed significantly between the IC/BPS and OAB groups; we used five unique questions and three measuring bother to generate a novel composite scoring system and nomogram that included urgency incontinence, bladder pain and symptomatic bother domains to differentiate these populations, which was validated in a second cohort of 150 patients. The addition of a self-reported bother index resulted in the creation of a diagnostic algorithm to identify and classify LUTS clusters across the total population.

RESULTS

While all validated questionnaires could distinguish between controls and patients with storage LUTS, no combined symptom scores differed significantly between the IC/BPS and OAB groups. These results are reflective of the prevalence of significant bladder pain (35%) in patients with OAB and the presence of urge incontinence (25%) in patients with IC/BPS. Only the fGUPI pain domain scores differed between patients in the OAB and IC/BPS groups, but it was not accurate enough for diagnostic evaluation (68% accuracy). Our composite scores and nomogram gave a much-improved diagnostic accuracy (94%) and demonstrated utility as a screening tool to identify storage LUTS in patients presenting for unrelated complaints, e.g. microhaematuria.

CONCLUSIONS

There is significant overlap of urinary tract symptoms between OAB and IC/BPS. We present a novel algorithm that provides a binary output capable of guiding clinical diagnosis. Future studies aimed at assessing the diagnostic value of novel classification schemes that address symptoms rather than specific diagnoses may improve patient prognosis.

Urothelial Tight Junction Barrier Dysfunction Sensitizes Bladder Afferents

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic voiding disorder that presents with pain in the urinary bladder and surrounding pelvic region. A growing body of evidence suggests that an increase in the permeability of the urothelium, the epithelial barrier that lines the interior of the bladder, contributes to the symptoms of IC/BPS. To examine the consequence of increased urothelial permeability on pelvic pain and afferent excitability, we overexpressed in the urothelium claudin 2 (Cldn2), a tight junction (TJ)-associated protein whose message is significantly upregulated in biopsies of IC/BPS patients. Consistent with the presence of bladder-derived pain, rats overexpressing Cldn2 showed hypersensitivity to von Frey filaments applied to the pelvic region. Overexpression of Cldn2 increased the expression of c-Fos and promoted the activation of ERK1/2 in spinal cord segments receiving bladder input, which we conceive is the result of noxious stimulation of afferent pathways. To determine whether the mechanical allodynia observed in rats with reduced urothelial barrier function results from altered afferent activity, we examined the firing of acutely isolated bladder sensory neurons. In patch-clamp recordings, about 30% of the bladder sensory neurons from rats transduced with Cldn2, but not controls transduced with GFP, displayed spontaneous activity. Furthermore, bladder sensory neurons with tetrodotoxin-sensitive (TTX-S) action potentials from rats transduced with Cldn2 showed hyperexcitability in response to suprathreshold electrical stimulation. These findings suggest that as a result of a leaky urothelium, the diffusion of urinary solutes through the urothelial barrier sensitizes bladders afferents, promoting voiding at low filling volumes and pain.

Treatment of painful bladder syndrome/interstitial cystitis with botulinum toxin A: why isn't it effective in all patients?

Botulinum toxin A (BTA) is currently used to treat a variety of painful disorders, including painful bladder syndrome/interstitial cystitis (PBS/IC). However, BTA is not consistently effective in all patients. This may be due to the disparity of causes of pain, but this may also relate to the processes by which BTA exerts anti-nociceptive effects. This review discusses mechanisms by which BTA may inhibit pain and studies of the use of BTA in PSB/IC patients. It is doubtful that any single treatment will effectively control pain in PBS/IC patients, and it is highly probable that multiple strategies will be required, both within individual patients and across the population of PBS/IC patients. The purpose of this review is to discuss those mechanisms by which BTA acts, with the intent that alternative strategies exploiting these mechanism, or work through alternative pathways, can be identified to more effectively treat pain in PBS/IC patients in the future.

Novel research approaches for interstitial cystitis/bladder pain syndrome: thinking beyond the bladder

Despite years of basic and clinical research focused on interstitial cystitis/bladder pain syndrome (IC/BPS), including clinical trials of candidate therapies, there remains an insufficient understanding of underlying cause(s), important clinical features and a lack of effective treatments for this syndrome. Progress has been limited and is likely due to many factors, including a primary focus on the bladder and lower urinary tract as origin of symptoms without adequately considering the potential influence of other local (pelvic) or systemic factors. Traditionally, there has been a lack of sufficiently diverse expertise and application of novel, integrated methods to study this syndrome. However, some important insights have been gained. For example, epidemiological studies have revealed that IC/BPS is commonly associated with other chronic pain conditions, including fibromyalgia, irritable bowel syndrome and chronic fatigue syndrome. These observations suggest that IC/BPS may involve systemic pathophysiology, including alterations of the central nervous system in some patients. Furthermore, there may be multiple causes and contributing factors that manifest in the symptoms of IC/BPS leading to multiple patient sub-groups or phenotypes. Innovative research is necessary to allow for a more complete description of the relationship between this syndrome and other disorders with overlapping symptoms. This report provides examples of such innovative research studies and their findings which have the potential to provide fresh insights into IC/BPS and disorders associated with chronic pain through characterization of broad physiologic systems, as well as assessment of the contribution of the bladder and lower urinary tract. They may also serve as models for future investigation of symptom-based urologic and non-urologic disorders that may remain incompletely characterized by previous, more traditional research approaches. Furthermore, it is anticipated a more holistic understanding of chronic urologic pain and dysfunction will ensue from productive interactions between IC/BPS studies like those described here and broader cutting-edge research endeavors focused on potentially related chronic pain disorders. A more comprehensive vision for IC/BPS inquiry is anticipated to yield new insights into basic disease mechanisms and clinical characteristics that will inform future research studies that will lead to more effective therapies and improved clinical care for these patients.

Increased urothelial paracellular transport promotes cystitis

Changes in the urothelial barrier are observed in patients with cystitis, but whether this leads to inflammation or occurs in response to it is currently unknown. To determine whether urothelial barrier dysfunction is sufficient to promote cystitis, we employed in situ adenoviral transduction to selectively overexpress the pore-forming tight junction-associated protein claudin-2 (CLDN-2). As expected, the expression of CLDN-2 in the umbrella cells increased the permeability of the paracellular route toward ions, but not to large organic molecules. In vivo studies of bladder function revealed higher intravesical basal pressures, reduced compliance, and increased voiding frequency in rats transduced with CLDN-2 vs. controls transduced with green fluorescent protein. While the integrity of the urothelial barrier was preserved in the rats transduced with CLDN-2, we found that the expression of this protein in the umbrella cells initiated an inflammatory process in the urinary bladder characterized by edema and the presence of a lymphocytic infiltrate. Taken together, these results are consistent with the notion that urothelial barrier dysfunction may be sufficient to trigger bladder inflammation and to alter bladder function.

Sympathetic nervous system and inflammation: a conceptual view

The peripheral sympathetic nervous system is organized into function-specific pathways that transmit the activity from the central nervous system to its target tissues. The transmission of the impulse activity in the sympathetic ganglia and to the effector tissues is target cell specific and guarantees that the centrally generated command is faithfully transmitted. This is the neurobiological basis of autonomic regulations in which the sympathetic nervous system is involved. Each sympathetic pathway is connected to distinct central circuits in the spinal cord, lower and upper brain stem and hypothalamus. In addition to its conventional functions, the sympathetic nervous system is involved in protection of body tissues against challenges arising from the environment as well as from within the body. This function includes the modulation of inflammation, nociceptors and above all the immune system. Primary and secondary lymphoid organs are innervated by sympathetic postganglionic neurons and processes in the immune tissue are modulated by activity in these sympathetic neurons via adrenoceptors in the membranes of the immune cells (see Bellinger and Lorton, 2014). Are the primary and secondary lymphoid organs innervated by a functionally specific sympathetic pathway that is responsible for the modulation of the functioning of the immune tissue by the brain? Or is this modulation of immune functions a general function of the sympathetic nervous system independent of its specific functions? Which central circuits are involved in the neural regulation of the immune system in the context of neural regulation of body protection? What is the function of the sympatho-adrenal system, involving epinephrine, in the modulation of immune functions?