Autonomic innervation of immune organs and neuroimmune modulation

Inflammation and cardiorespiratory control: the role of the vagus nerve

Inflammation and immunity have been implicated in a wide variety of diseases and disorders ranging from asthma to cardiovascular disease to hemorrhagic shock. In this review we will briefly consider the evidence for the neural concomitants of immunomodulation. First, we will briefly review the anatomy and physiology of the cardiorespiratory system. Then we will review the anatomy and physiology of neural-immune communication. The nucleus of the solitary tract is a site of integration of both the afferent and efferent neural regulation of the cardiorespiratory as well as the immune system. Then we will provide an overview of what is known about neuroimmunomodulation from both animal and human studies including neuroimaging and clinical studies. Finally, we will discuss a possible role of this neural circuitry in asthma related health disparities.

Neuropeptides of human thymus in normal and pathological conditions

Human thymus of healthy subjects and patients affected by thymoma-associated Myastenia Gravis were studied in order to visualize and compare the morphological distributive pattern of four neuropeptides: vasoactive intestinal peptide, substance P, neuropeptide Y, and neurotensin. Based on our observations, we formulated hypotheses on their relations in neuro-immunomodulation under physiological and pathophysiological conditions. Immuno-histochemical staining for neuropeptides was performed and morphological and morphometrical analyses were conducted on healthy and diseased thymus. In normal thymus, a specific distributive pattern was observed for the several neuropeptide-positive nerves in different thymus lobular zones. In particular substance P-positive fibers were observed in subcapsular zone, specifically located into parenchyma, where they represent the almost total amount of fibers; neurotensin-positive fibers were observed primarily located in parenchyma than perivascular site of several thymus lobular zones, and more abundant the cortico-medullary and medullary zones. Instead VIP- and NPY-positive fibers were widely distributed in perivascular and parenchymal sites of several thymus lobular zones. In thymoma, the distribution of neuropeptide-positive fibers was quantitatively reduced, while cells immunopositive to VIP and substance P were quantitatively increased and dispersed. Observation of the perivascular and parenchymal distribution of the analyzed neuropeptides suggests evidence that a regulatory function is performed by nerves and cells that secrete neuropeptide into the thymus. The alteration of neuropeptide patterns in thymoma suggests that these neurotransmitters play a role in autoimmune diseases such as Myastenia Gravis.

The splenic response to ischemic stroke: what have we learned from rodent models?

The majority of promising experimental compounds have failed in clinical trials, highlighting the need for novel approaches to treat stroke. Much research has been devoted to elucidating the signaling pathways involved in delayed neuroinflammation that can be targeted at clinically relevant time points. The field of stroke research has benefited from experiments characterizing the temporal expression profiles of candidate cytokines, chemokines, matrix metalloproteinases, and other putative pro-inflammatory molecules. Yet, these data have offered only a glimpse into the complex pathological sequelae and have not advanced the treatment of neuropathies. Upon recognition that peripheral immune cell activation is involved in penumbral expansion, the spleen has emerged as a novel target that mediates the peripheral immune response and promotes pro-inflammatory injury. Although the precise mechanisms have yet to be elucidated, accumulated evidence demonstrates that focal cerebral ischemia alters cytokine, chemokine, and immune cell profiles in the spleen. Additionally, removal of this peripheral lymphoid organ is neuroprotective, and the efficacy of several protective therapies has been linked to actions at the level of the spleen. Future experiments aimed at identifying the splenic lymphocyte populations that respond to ischemic stroke, as well as their signaling mechanisms, are critical in developing novel therapies.

Neural aspects of immunomodulation: focus on the vagus nerve

Inflammation and immunity have been implicated in a wide variety of diseases and disorders ranging from Alzheimer's disease to cardiovascular disease to hemorrhagic shock. In this review, we will briefly consider the evidence for the neural concomitants of immunomodulation. First, we will briefly review the anatomy and physiology of neural-immune communication. Evidence for the somatotopic organization of the vagus nerve and for pain processes suggests that such an organization may be relevant for the investigation of the neural concomitants of immunity. Then we will provide an overview of what is known from both animal and human studies including neuroimaging and clinical studies. Finally, we will discuss some of the challenges and opportunities in this exciting area of investigation.

Impaired immune responses following spinal cord injury lead to reduced ability to control viral infection

Spinal cord injuries disrupt central autonomic pathways that regulate immune function, and increasing evidence suggests that this may cause deficiencies in immune responses in people with spinal cord injuries. Here we analyze the consequences of spinal cord injury (SCI) on immune responses following experimental viral infection of mice. Female C57BL/6 mice received complete crush injuries at either thoracic level 3 (T3) or 9 (T9), and 1 week post-injury, injured mice and un-injured controls were infected with different dosages of mouse hepatitis virus (MHV, a positive-strand RNA virus). Following MHV infection, T3- and T9-injured mice exhibited increased mortality in comparison to un-injured and laminectomy controls. Infection at all dosages resulted in significantly higher viral titer in both T3- and T9-injured mice compared to un-injured controls. Investigation of anti-viral immune responses revealed impairment of cellular infiltration and effector functions in mice with SCI. Specifically, cell-mediated responses were diminished in T3-injured mice, as seen by reduction in virus-specific CD4(+) T lymphocyte proliferation and IFN-γ production and decreased numbers of activated antigen presenting cells compared to infected un-injured mice. Collectively, these data indicate that the inability to control viral replication following SCI is not level dependent and that increased susceptibility to infection is due to suppression of both innate and adaptive immune responses.

Luminal administration ex vivo of a live Lactobacillus species moderates mouse jejunal motility within minutes

Gut commensals modulate host immune, endocrine, and metabolic functions. They also affect peripheral and central neural reflexes and function. We have previously shown that daily ingestion of Lactobacillus reuteri (LR) for 9 d inhibits the pseudoaffective cardiac response and spinal single-fiber discharge evoked by visceral distension, and decreases intestinal motility and myenteric AH cell slow afterhyperpolarization (sAHP) by inhibiting a Ca-activated K (IK(Ca)) channel. We tested whether luminal LR could acutely decrease motility in an ex vivo perfusion model of naive Balb/c jejunum. Live LR dose dependently decreased motor complex pressure wave amplitudes with 9- to 16-min onset latency and an IC(50) of 5 × 10(7) cells/ml Krebs. Heat-killed LR or another live commensal, Lactobacillus salivarius, were without effect. The IK(Ca) channel blocker TRAM-34, but neither the opener (DCEBIO) nor the hyperpolarization-activated cationic channel inhibitor ZD7288 (5 μM) (or TTX 1 μM), mimicked the LR effect on motility acutely ex vivo. We provide evidence for a rapid, strain-specific, dose-dependent action of a live Lactobacillus on small intestinal motility reflexes that recapitulates the long-term effects of LR ingestion. These observations may be useful as a first step to unraveling the pathways involved in bacteria to the nervous system communication.

The immunoregulatory role of dopamine: an update

The neurotransmitter dopamine (DA) is an important molecule bridging the nervous and immune systems. DA through autocrine/paracrine manner modulates the functions of immune effector cells by acting through its receptors present in these cells. DA also has unique and opposite effects on T cell functions. Although DA activates naïve or resting T cells, but it inhibits activated T cells. In addition, changes in the expression of DA receptors and their signaling pathways especially in T cells are associated with altered immune functions in disorders like schizophrenia and Parkinson's disease. These results suggest an immunoregulatory role of DA. Therefore, targeting DA receptors and their signaling pathways in these cells by using DA receptor agonists and antagonists may be useful for the treatment of diseases where DA induced altered immunity play a pathogenic role.

Intrinsic innervation and dopaminergic markers after experimental denervation in rat thymus

The aim of this study was to examine rat thymus innervation using denervation techniques and to explore the related microanatomical localization of dopamine, D1, D2 receptors and dopamine membrane transporter (DAT).

In the thymus subcapsular region, the parenchymal cholinergic fibers belong exclusively to phrenic nerve branching. No somatic phrenic nerve branching was detected in any other analysed thymus lobule regions.

In rats subjected to sympathetic or parasympathetic ablation, it was observed that catecholaminergic and cholinergic nerve fibers respectively contributed to forming plexuses along vessel walls.

In the subcapsular and septal region, no parenchymal nerve branching, belonging to sympathetic or parasympathetic nervous system was noted. Instead, in the deep cortical region, cortico-medullary junction (CM-j) and medulla, catecholaminergic and cholinergic nerve fibers were detected along the vessels and parenchyma.

Dopamine and dopamine receptors were widely diffused in the lobular cortico-medullary junction region and in the medulla, where the final steps of thymocyte maturation and their trafficking take place.

No variation in dopamine and DAT immune reaction was observed following total or partial parasympathectomy or phrenic nerve cutting. After chemical or surgical sympathectomy however, neither dopamine nor DAT immune reaction was noted again. Instead, D1 and D2 dopamine receptor expression was not affected by thymus denervation.

In rats subjected to specific denervation, it was observed the direct intraparenchymal branching of the phrenic nerve and sympathetic and parasympathetic fibers into thymus parenchyma along vessels. These findings on the dopaminergic system highlight the importance of neurotransmitter receptor expression in the homeostasis of neuroimmune modulation.

The neurology of the immune system: neural reflexes regulate immunity

Parallel advances in neuroscience and immunology established the anatomical and cellular basis for bidirectional interactions between the nervous and immune systems. Like other physiological systems, the immune system--and the development of immunity--is modulated by neural reflexes. A prototypical example is the inflammatory reflex, comprised of an afferent arm that senses inflammation and an efferent arm, the cholinergic anti-inflammatory pathway, that inhibits innate immune responses. This mechanism is dependent on the alpha7 subunit of the nicotinic acetylcholine receptor, which inhibits NF-kappaB nuclear translocation and suppresses cytokine release by monocytes and macrophages. Here we summarize evidence showing that innate immunity is reflexive. Future advances will come from applying an integrative physiology approach that utilizes methods adapted from neuroscience and immunology.

Blood-forming stem cells are nervous: direct and indirect regulation of immature human CD34+ cells by the nervous system

The nervous system regulates immunity through hormonal and neuronal routes as part of host defense and repair mechanism. Here, we review the emerging evidence for regulation of human hematopoietic stem and progenitor cells (HSPC) by the nervous system both directly and indirectly via their bone marrow (BM) niche-supporting stromal cells. Functional expression of several neurotransmitter receptors was demonstrated on HSPC, mainly on the more primitive CD34(+)/CD38(-/low) fraction. The myeloid cytokines, G-CSF and GM-CSF, dynamically upregulate neuronal receptor expression on human HSPC. This is followed by an increased response to neurotransmitters, leading to enhanced proliferation and motility of human CD34(+) progenitors, repopulation of the murine BM and their egress to the circulation. Importantly, recent observations showed rapid mobilization of human HSPC to high SDF-1 expressing ischemic tissues of stroke individuals followed by neoangiogenesis, neurological and functional recovery. Along with decreased levels of circulating immature CD34(+) cells and SDF-1 blood levels found in patients with early-stage Alzheimer's disease, these findings suggest a possible involvement of human HSPC in brain homeostasis and thus their potential clinical applications in neuropathology.

Reduced levels of immunoglobulin in children with autism correlates with behavioral symptoms

OBJECTIVES

To assay if plasma antibody levels in children with autism or developmental delays (DD) differ from those with typical development as an indicator of immune function and to correlate antibody levels with severity of behavioral symptoms.

METHODS

Plasma was collected from children with autistic disorder (AU; n=116), DD but not autism (n=32), autism spectrum disorder but not full autism (n=27), and age-matched typically developing (TD) controls (n=96). Samples were assayed for systemic levels of immunoglobulin (IgG, IgM, IgA, and IgE) by enzyme-linked immunosorbent assay. Subjects with autism were evaluated using the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised, and all subjects were scored on the Aberrant Behavior Checklist (ABC) by the parents. Numerical scores for each of the ABC subscales as well as the total scores were then correlated with Ig levels.

RESULTS

Children with AU have a significantly reduced level of plasma IgG (5.39+/-0.29 mg/mL) compared to the TD (7.72+/-0.28 mg/mL; P<0.001) and DD children (8.23+/-0.49 mg/mL; P<0.001). Children with autism also had a reduced level of plasma IgM (0.670.06 mg/mL) compared to TD (0.79+/-0.05 mg/mL; P<0.05). Ig levels were negatively correlated with ABC scores for all children (IgG: r=-0.334, P<0.0001; IgM: r=-0.167, P=0.0285).

CONCLUSION

Children with AU have significantly reduced levels of plasma IgG and IgM compared to both DD and TD controls, suggesting an underlying defect in immune function. This reduction in specific Ig levels correlates with behavioral severity, where those patients with the highest scores in the behavioral battery have the most reduced levels of IgG and IgM.

Postural changes in blood pressure associated with interactions between candidate genes for chronic respiratory diseases and exposure to particulate matter

BACKGROUND

Fine particulate matter [aerodynamic diameter </= 2.5 mum (PM(2.5))] has been associated with autonomic dysregulation.

OBJECTIVE

We hypothesized that PM(2.5) influences postural changes in systolic blood pressure (DeltaSBP) and in diastolic blood pressure (DeltaDBP) and that this effect is modified by genes thought to be related to chronic lung disease.

METHODS

We measured blood pressure in participants every 3-5 years. DeltaSBP and DeltaDBP were calculated as sitting minus standing SBP and DBP. We averaged PM(2.5) over 48 hr before study visits and analyzed 202 single nucleotide polymorphisms (SNPs) in 25 genes. To address multiple comparisons, data were stratified into a split sample. In the discovery cohort, the effects of SNP x PM(2.5) interactions on DeltaSBP and DeltaDBP were analyzed using mixed models with subject-specific random intercepts. We defined positive outcomes as p < 0.1 for the interaction; we analyzed only these SNPs in the replicate cohort and confirmed them if p < 0.025 with the same sign. Confirmed associations were analyzed within the full cohort in models adjusted for anthropometric and lifestyle factors.

RESULTS

Nine hundred forty-five participants were included in our analysis. One interaction with rs9568232 in PHD finger protein 11 (PHF11) was associated with greater DeltaDBP. Interactions with rs1144393 in matrix metalloprotease 1 (MMP1) and rs16930692, rs7955200, and rs10771283 in inositol 1,4,5-triphosphate receptor, type 2 (ITPR2) were associated with significantly greater DeltaSBP. Because SNPs associated with DeltaSBP in our analysis are in genes along the renin-angiotensin pathway, we then examined medications affecting that pathway and observed significant interactions for angiotensin receptor blockers but not angiotensin-converting enzyme inhibitors with PM(2.5).

CONCLUSIONS

PM(2.5) influences blood pressure and autonomic function. This effect is modified by genes and drugs that also act along this pathway.

Cholinergic control of inflammation

Cytokine production is necessary to protect against pathogens and promote tissue repair, but excessive cytokine release can lead to systemic inflammation, organ failure and death. Inflammatory responses are finely regulated to effectively guard from noxious stimuli. The central nervous system interacts dynamically with the immune system to modulate inflammation through humoral and neural pathways. The effect of glucocorticoids and other humoral mediators on inflammatory responses has been studied extensively in the past decades. In contrast, neural control of inflammation has only been recently described. We summarize autonomic regulation of local and systemic inflammation through the 'cholinergic anti-inflammatory pathway', a mechanism consisting of the vagus nerve and its major neurotransmitter, acetylcholine, a process dependent on the nicotinic acetylcholine receptor alpha7 subunit. We recapitulate additional sources of acetylcholine and their contribution to the inflammatory response, as well as acetylcholine regulation by acetylcholinesterase as a means to attenuate inflammation. We discuss potential therapeutic applications to treat diseases characterized by acute or chronic inflammation, including autoimmune diseases, and propose future research directions.

Blockade of adrenoreceptors inhibits the splenic response to stroke

Recent studies have highlighted the involvement of the peripheral immune system in delayed cellular degeneration after stroke. In the permanent middle cerebral artery occlusion (MCAO) model of stroke, the spleen decreases in size. This reduction occurs through the release of splenic immune cells. Systemic treatment with human umbilical cord blood cells (HUCBC) 24 h post-stroke blocks the reduction in spleen size while significantly reducing infarct volume. Splenectomy 2 weeks prior to MCAO also reduces infarct volume, further demonstrating the detrimental role of this organ in stroke-induced neurodegeneration. Activation of the sympathetic nervous system after MCAO results in elevated catecholamine levels both at the level of the spleen, through direct splenic innervation, and throughout the systemic circulation upon release from the adrenal medulla. These catecholamines bind to splenic alpha and beta adrenoreceptors. This study examines whether catecholamines regulate the splenic response to stroke. Male Sprague-Dawley rats either underwent splenic denervation 2 weeks prior to MCAO or received injections of carvedilol, a pan adrenergic receptor blocker, prazosin, an alpha1 receptor blocker, or propranolol, a beta receptor blocker. Denervation was confirmed by reduced splenic expression of tyrosine hydroxylase. Denervation prior to MCAO did not alter infarct volume or spleen size. Propranolol treatment also had no effects on these outcomes. Treatment with either prazosin or carvedilol prevented the reduction in spleen size, yet only carvedilol significantly reduced infarct volume (p < 0.05). These results demonstrate that circulating blood borne catecholamines regulate the splenic response to stroke through the activation of both alpha and beta adrenergic receptors.

Stem cell regulation via dynamic interactions of the nervous and immune systems with the microenvironment

Physiological interactions between the nervous and immune systems with components of the local microenvironment are needed to maintain homeostasis throughout the body. Dynamic regulation of bone remodeling, hematopoietic stem cells, and their evolving niches via neurotransmitter signaling are part of the host defense and repair mechanisms. This crosstalk links activated leukocytes, neuronal, and stromal cells, which combine to directly and indirectly regulate hematopoietic stem cells. Together, interactions between diverse systems create a regulatory "brain-bone-blood triad," contributing an additional dimension to the concept of the hematopoietic stem cell niche.

Dopamine, vesicular transporters and dopamine receptor expression and localization in rat thymus and spleen

The localization of dopamine stores and the expression and localization of vesicular monoamine transporter (VMAT) type-1 and 2 and of dopamine D1-like and D2-like receptor subtypes were investigated in rat thymus and spleen by immunohistochemical, immunochemical techniques and by RT-PCR. In the thymus dopamine immunoreactivity was developed in the cortico-medullary junction and in the medulla, but not in the thymic cortex. In the spleen, dopamine stores were found in reticular structures in the white pulp border and in the white pulp, but not in the red one. Both thymus and spleen expressed VMAT-1 and VMAT-2 immunoreactivity as well as dopamine D1, D2, D3, D4 and D5 receptor immunoreactivity. Immunohistochemistry revealed VMAT-1, VMAT-2 and dopamine D1, D2, D3, D4 and D5 receptor immunoreactivity primarily in the thymic cortical-medulla transitional zone and to a lesser extent in the medulla but not in the cortex. In the spleen, VMAT-1, VMAT-2 and dopamine D1, D2, D3, D4 and D5 receptor immunoreactivity was located primarily in the white pulp border and to a lesser extent in the white pulp. These findings indicate that both thymus and spleen express a dopaminergic system characterized by the presence of dopamine, vesicular monoamine transporters and the five subtypes of dopamine receptors. The presence of these dopaminergic markers suggests that dopamine likely originating from immune cells and/or from sympathetic neuroeffector plexus is released in the lymphoid microenvironment. Based on the microanatomical localization of dopaminergic markers investigated, a role of dopamine in maturation and selection of lymphocytes and activation of immune responses is suggested.

Splenic constriction during isometric handgrip exercise in humans

During the first minute of a moderate-intensity isometric handgrip (HG) exercise, there is an increase in stroke volume and cardiac output that occurs without any change in systemic vascular conductance. Although the mechanism of increased venous return is not yet known, current focus has been placed on the constriction of visceral organs. The human spleen represents a compliant organ with high perfusion that constricts during the rather severe stresses of maximal exercise, a diving reflex, or prolonged apnea. This study tested the hypothesis that spleen constriction occurs during isometric HG exercise. Eight participants performed a 1 min isometric HG test at 40% maximum voluntary contraction. Splenic length and width were measured (with ultrasound imaging) after 1 min of exercise, and volume was calculated. To investigate the reflex specificity of this response, spleen dimensions were also measured during 4 min of lower-body negative pressure (LBNP; –20 mm Hg). To test the additional impact of altered breathing and intra-abdominal pressures during the HG, measures were also taken during Valsalva’s manoeuvre (VM) at 30 mm Hg. Compared with baseline, both length and width of the spleen were reduced by 0.20 to 0.55 cm (or 4.44%–6.09%; p < 0.05) during each test. This resulted in relative reductions in splenic volume of 13 ± 1% (HG), 9% ± 7% (LBNP) and 18% ± 7% (VM) (p < 0.05; all mean ± SD). It was concluded that the spleen can constrict during the first minute of isometric HG exercise.

Neuritogenic effects of T cell-derived IL-3 on mouse splenic sympathetic neurons in vivo

To determine the role played by lymphocytes and cytokines in the growth of sympathetic neurons in vivo, the innervation and cytokine levels were examined in the spleens of SCID mice that lack T and B cells. Splenic noradrenaline, nerve growth factor (NGF), and IL-1beta levels were elevated in SCID mice. Immunohistochemical examination revealed that the density of tyrosine hydroxylase-positive (TH(+)) fibers of splenic central arteries in SCID mice was increased compared with wild-type C.B-17 mice, while SCID mice had significantly fewer TH(+) fibers in their periarteriolar lymphatic sheaths (PALS). Two weeks after SCID mice were injected with C.B-17 splenic T cells, their TH(+) fiber staining increased in the PALS. IL-3 levels increased significantly in SCID mice following T cell reconstitution, and the administration of anti-IL-3 Ab blocked the above T cell-induced increase in innervation in the PALS. Anti-IL-3 treatment also inhibited the regeneration of splenic sympathetic neurons in C.B-17 mice after they were chemically sympathetomized with 6-hydroxydopamine. Depletion of NK cells by anti-asialo GM1 promoted the splenic innervation in SCID mice, while there were no significant changes in the innervation between CD8(+) T cell-deficient beta(2)-microglobulin knockout mice and their wild type. Our results suggest that T cells (probably CD4(+) Th cells but not CD8(+) CTLs) play a role in regulating the sympathetic innervation of the spleen; this effect appeared to be mediated, at least in part, by IL-3. On the contrary, NK cells may exert an inhibitory effect on the sympathetic innervation.

Autonomic renal denervation ameliorates experimental glomerulonephritis

Increasing evidence indicates that inflammation of visceral organs is significantly affected by the autonomic nervous system. Such neuroimmune interactions have not been studied in the kidney. Here, we show that the rat kidney is innervated by both tyrosine hydroxylase-positive sympathetic efferent nerve fibers and calcitonin gene-related peptide-positive primary afferent nerve fibers, both of which are found in proximity to macrophages and dendritic cells. Complete surgical bilateral renal denervation was performed 2 d before glomerulonephritis was induced by injecting the monoclonal anti-Thy-1.1 antibody OX-7. Denervation significantly reduced albuminuria, mesangiolysis, formation of microaneurysms, deposition of glomerular collagen IV, and expression of TGF-beta compared with sham-operated controls. Accordingly, inflammation, identified by accumulation of interstitial macrophages and renal expression of TNF-alpha, and mesangial cell proliferation were significantly reduced. These findings indicate that autonomic renal denervation ameliorates and, by inference, innervation exacerbates acute inflammation in the kidney; therefore, neurotransmitters or neuropeptides and their receptors might represent novel targets for the treatment of acute glomerulonephritis.

Pain and stress in a systems perspective: reciprocal neural, endocrine, and immune interactions

This paper advances a psychophysiological systems view of pain in which physical injury, or wounding, generates a complex stress response that extends beyond the nervous system and contributes to the experience of pain. Through a common chemical language comprising neurotransmitters, peptides, endocannabinoids, cytokines, and hormones, an ensemble of interdependent nervous, endocrine, and immune processes operates in concert to cope with the injury. These processes act as a single agent and comprise a supersystem. Acute pain in its multiple dimensions, and the related symptoms that commonly occur with it, are products of the supersystem. Chronic pain can develop as a result of unusual stress. Social stressors can compound the stress resulting from a wound or act alone to dysregulate the supersystem. When the supersystem suffers dysregulation, health, function, and sense of well-being suffer. Some chronic pain conditions are the product of supersystem dysregulation. Individuals vary and are vulnerable to dysregulation and dysfunction in particular organ systems due to the unique interactions of genetic, epigenetic and environmental factors, as well as the past experiences that characterize each person.

PERSPECTIVE

Acute tissue injury activates an ensemble of interdependent nervous, endocrine, and immune processes that operate in concert and comprise a supersystem. Some chronic pain conditions result from supersystem dysregulation. Individuals vary and are vulnerable to dysregulation due to the unique interactions of genetic, epigenetic, and environmental factors and past experiences that characterize each person. This perspective can potentially assist clinicians in assessing and managing chronic pain patients.

Autoantibodies in autism spectrum disorders (ASD)

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disorders defined behaviorally by abnormalities in social, verbal, and nonverbal communication. The etiologies of ASD are unknown, likely to be the result of a variety of numerous genetic, neurological, environmental, and immunological interactions that lead to a general behavioral phenotype defined as ASD. This review will focus on the various immune system anomalies, in particular, autoantibodies, which have been reported in subjects with ASD. In addition, we will discuss recent studies performed by our group concerning the presence of autoantibodies directed against neural antigens, which are observed in patients with ASD.

Ontogeny of intrinsic innervation in the human thymus and spleen

The ontogeny of the innervation of human lymphoid organs has not been studied in detail. Our aim was to assess the nature and distribution of parenchymal nerves in human fetal thymus and spleen. We used the peroxidase immunohistochemical technique with antibodies specific to neuron-specific enolase (NSE), neurofilaments (NF), PGP9.5, S100 protein, and tyrosine hydroxylase (TH) and evaluated our results with image analysis. In human fetal thymus, NSE-, NF-, S100-, PGP9.5-, and TH-positive nerves were identified associated with large blood vessels from 18 gestational weeks (gw) onwards, increasing in density during development. Their branches penetrated the septal areas at 20 gw, reaching the cortex and the corticomedullary junction between 20 and 23 gw. Few nerve fibers were seen in the medulla in close association with Hassall's corpuscles. In human fetal spleen, NSE-, NF-, S100-, PGP9.5-, and TH-positive nerve fibers were localized in the connective tissue surrounding the splenic artery at 18 gw. Perivascular NSE-, NF-, S100-, PGP9.5-, and TH-positive nerve fibers were seen extending into the white pulp, mainly in association with the central artery and its branches, increasing in density during gestation. Scattered NSE-, NF-, S100-, PGP9.5-, and TH-positive nerve fibers and endings were localized in the red pulp from 18 gw onward. The predominant perivascular distribution of most parenchymal nerves implies that thymic and splenic innervation may play an important functional role during intrauterine life.

Anatomical evidence for enteric neuroimmune interactions in Peyer's patches

Peyer's patches (PP), a key component of the gut-associated lymphoid tissue, serve as the primary inductive sites for intestinal immunity. In the present study, we addressed the hypothesis that the morphological features of PP innervation are consistent with an immunomodulatory role for the enteric nervous system. Laser scanning confocal microscopy was used to collect images through large tissue volumes, yielding a three-dimensional perspective of the neuronal network superimposed on PP follicles from porcine jejunum and human ileum. Peptidergic nerve fibers were found in close apposition to immunocytes within PP subepithelial domes and the adjacent villi. The results suggest that nerve fibers in PP may participate in neuroimmune cross-talk within individual antigen-sampling sites as well as integrate information across multiple antigen-sampling sites.

Effects of footbathing on autonomic nerve and immune function

The purpose of this study was to investigate the effects of footbathing on autonomic nerve and immune function. Eleven healthy female volunteers (aged 22-24 years) undertook footbaths at 42 degrees C for 10 min, with or without additional mechanical stimulation (air bubbles and vibration). Autonomic responses were evaluated by electrocardiography and spectral analysis of heart rate variability, and by measurement of blood flow in the sural region. White blood cell (WBC) counts, ratios of lymphocyte subsets, and natural killer (NK) cell cytotoxicity were used as indicators of immune function. Footbathing with mechanical stimulation produced (1) significant changes in the measured autonomic responses, indicating a shift to increased parasympathetic and decreased sympathetic activity and (2) significant increases in WBC count and NK cell cytotoxicity, suggesting an improved immune status. Because these physiological changes are likely to be of benefit to health, our findings support the use of footbathing in nursing practice.

Neuroimmune link in the mucosa of chronic gastritis with Helicobacter pylori infection

It is suggested that different neuropeptides regulate gastric mucosal integrity and participate in the development of chronic gastritis. The aim of this study was to examine the roles and changes of immunoreactive (IR) nerves and immunocompetent cells in human gastritis. Immunohistochemical, immunocytochemical, and confocal laser microscopic methods were used. All investigated nerve fibers were found in different quantities in the mucosa of both control and gastritis samples. The number of SP, NPY, and VIP IR nerve fibers increased significantly (P < 0.05) in gastritis. No IR immunocompetent cells (lymphocytes, plasma cells, mast cells) were found in the control, however, some showed NPY (16.8%) and SP (9.4%) immunoreactivity in chronic gastritis. The distance between nerve fibers and immunocompetent cells was 200 nm to 1 microm. In conclusion, the increased number of SP, NPY, and VIP IR nerves and IR immunocytes suggests that they participate in development of neurogenic inflammation, repairing processes of chronic gastritis.

Omega-3 fatty acid status in attention-deficit/hyperactivity disorder

Lower levels of long-chain polyunsaturated fatty acids, particularly omega-3 fatty acids, in blood have repeatedly been associated with a variety of behavioral disorders including attention-deficit/hyperactivity disorder (ADHD). The exact nature of this relationship is not yet clear. We have studied children with ADHD who exhibited skin and thirst symptoms classically associated with essential fatty acid (EFA) deficiency, altered plasma and red blood cell fatty acid profiles, and dietary intake patterns that do not differ significantly from controls. This led us to focus on a potential metabolic insufficiency as the cause for the altered fatty acid phenotype. Here we review previous work and present new data expanding our observations into the young adult population. The frequency of thirst and skin symptoms was greater in newly diagnosed individuals with ADHD (n = 35) versus control individuals without behavioral problems (n = 112) drawn from the Purdue student population. A follow up case-control study with participants willing to provide a blood sample, a urine sample, a questionnaire about their general health, and dietary intake records was conducted with balancing based on gender, age, body mass index, smoking and ethnicity. A number of biochemical measures were analyzed including status markers for several nutrients and antioxidants, markers of oxidative stress, inflammation markers, and fatty acid profiles in the blood. The proportion of omega-3 fatty acids was found to be significantly lower in plasma phospholipids and erythrocytes in the ADHD group versus controls whereas saturated fatty acid proportions were higher. Intake of saturated fat was 30% higher in the ADHD group, but intake of all other nutrients was not different. Surprisingly, no evidence of elevated oxidative stress was found based on analysis of blood and urine samples. Indeed, serum ferritin, magnesium, and ascorbate concentrations were higher in the ADHD group, but iron, zinc, and vitamin B6 were not different. Our brief survey of biochemical and nutritional parameters did not give us any insight into the etiology of lower omega-3 fatty acids, but considering the consistency of the observation in multiple ADHD populations continued research in this field is encouraged.

Dopamine plasma membrane transporter (DAT) in rat thymus and spleen: an immunochemical and immunohistochemical study

The expression of the dopamine plasma membrane transporter (DAT) was investigated in rat thymus and spleen by immunochemical and immunohistochemical techniques. Antibodies raised against a peptide mapping near the amino terminus of DAT were bound to a single band of approximately 76 kDa in thymus and spleen membranes as well as in striatal and kidney membranes which were used as dopaminergic reference tissues. Reverse transcription-polymerase chain reaction analysis revealed that both thymus and spleen expressed DAT mRNA. Immunohistochemistry revealed in rat thymus a DAT immune reaction in the wall of arteries located in septa of connective tissue as well as in the medulla, with a reticular localization and an apparent negative reaction of thymocytes. In the spleen, DAT immunoreactivity was located primarily in the red-white pulp marginal zone, within small cells, likely corresponding to lymphocytes and in the wall of white pulp arteries. The presence of a dopamine transporter suggests that dopamine released in the lymphoid microenvironment may contribute to neuroimmune modulation. It cannot be excluded a different activity of dopamine in primary and secondary immune organs, such as maturation and selection of lymphocytes and activation of immune responses in the spleen.

A fundamental bimodal role for neuropeptide Y1 receptor in the immune system

Psychological conditions, including stress, compromise immune defenses. Although this concept is not novel, the molecular mechanism behind it remains unclear. Neuropeptide Y (NPY) in the central nervous system is a major regulator of numerous physiological functions, including stress. Postganglionic sympathetic nerves innervating lymphoid organs release NPY, which together with other peptides activate five Y receptors (Y1, Y2, Y4, Y5, and y(6)). Using Y1-deficient (Y1(-/-)) mice, we showed that Y1(-/-) T cells are hyperresponsive to activation and trigger severe colitis after transfer into lymphopenic mice. Thus, signaling through Y1 receptor on T cells inhibits T cell activation and controls the magnitude of T cell responses. Paradoxically, Y1(-/-) mice were resistant to T helper type 1 (Th1) cell-mediated inflammatory responses and showed reduced levels of the Th1 cell-promoting cytokine interleukin 12 and reduced interferon gamma production. This defect was due to functionally impaired antigen-presenting cells (APCs), and consequently, Y1(-/-) mice had reduced numbers of effector T cells. These results demonstrate a fundamental bimodal role for the Y1 receptor in the immune system, serving as a strong negative regulator on T cells as well as a key activator of APC function. Our findings uncover a sophisticated molecular mechanism regulating immune cell functions that can lead to stress-induced immunosuppression.

Paraneoplastic neurodegeneration in a murine host following progressive growth of a spontaneous T-Cell lymphoma: role of proinflammatory internal responses

OBJECTIVE(S)

In the present study, the mechanism of paraneoplastic neurodegeneration associated with progressive in vivo growth of a T-cell lymphoma of spontaneous origin has been investigated.

METHODS

Histologically, the brain was investigated by hematoxylin-eosin staining of brain sections. Western blotting was performed to detect the expression of cytokines and other proteins. Macrophage-derived interleukin-1 (IL-1) and tumor necrosis factor (TNF) was estimated by immunoassays. Induction of apoptosis in brain and tumor cells was determined by percent specific DNA fragmentation.

RESULTS

Tumor growth was associated with the development of multiple lesions in various regions of the brain along with alterations in the structure and alignment of Purkinje cells, and an increase in the water content in the brain. Brain extract and serum of tumor-bearing mice showed higher levels of proinflammatory cytokines. Induction of apoptosis is suggested to be the cause underlying the loss of cellularity of tumor-bearing hosts in the brain owing to an augmentation in the induction of the caspase-dependent pathway of programmed cell death. Further, the study presents investigations to show the role of nitric oxide and proinflammatory cytokines IL-1, TNF, interferon-gamma and alkaline phosphatase in the manifestation of paraneoplastic neurodegeneration.

CONCLUSIONS

Growth of a T-cell lymphoma is associated with the manifestation of neurodegeneration caused by soluble proinflammatory factors of tumor and/or host origin.