The Role of Noradrenergic Nerves in the Development of the Lymphoproliferative Disease in Fas-Deficient, lpr/lpr Mice

Systemic autoimmune abnormalities alter the morphology of mucosa-associated lymphoid tissues in the rectum of MRL/MpJ-Faslpr/lpr mice

Systemic autoimmune diseases (ADs) might affect the morphology and function of gut-associated lymphoid tissue (LTs) indirectly; however, their exact relationship remains unclear. Therefore, we investigated mouse LTs in the anorectal canal and morphologically compared them between MRL/MpJ-Fas+/+ and MRL/MpJ-Faslpr/lpr mice. LT aggregations, also known as rectal mucosa-associated lymphoid tissues (RMALTs), were exclusively seen in the lamina propria and submucosa of the rectum. The mean size and number of the LT aggregations both significantly increased in MRL/MpJ-Faslpr/lpr mice compared to those in MRL/MpJ-Fas+/+ mice. The distance from the anorectal junction to the first LT aggregate was significantly shorter in MRL/MpJ-Faslpr/lpr mice than that in MRL/MpJ-Fas+/+ mice. Immunostaining revealed that the RMALTs included CD3+, CD4+, and CD8+ T cells; B220+ B cells; IBA1+ macrophages; Ki67+ proliferative cells; and PNAd+ high-endothelial venules (HEVs). The numbers of macrophages, proliferative cells, CD4+ T cells, CD8+ T cells, and HEVs were significantly increased in MRL/MpJ-Faslpr/lpr mice compared to those in MRL/MpJ mice. Furthermore, the gene expression levels of chemokines (Cxcl9 and Cxcl13) and their corresponding receptors (Cxcr3 and Cxcr5) were significantly higher in MRL/MpJ-Faslpr/lpr mice than those in MRL/MpJ-Fas+/+ mice. Although the morphology of rectal epithelium was comparable between the strains, M cell number was significantly higher in MRL/MpJ-Faslpr/lpr mice than in MRL/MpJ-Fas+/+ mice. Thus, ADs could alter RMALT morphology, and quantitative changes in T-cell subsets, proliferative cells, macrophages, HEVs, chemokine expression, and M cells could affect their cell composition and development.

Chronic Effects of the Sympathetic Nervous System in Inflammatory Models

The immune system is embedded in a network of regulatory systems to keep homeostasis in case of an immunologic challenge. Neuroendocrine immunologic research has revealed several aspects of these interactions over the past decades, e.g., between the autonomic nervous system and the immune system. This review will focus on evidence revealing the role of the sympathetic nervous system (SNS) in chronic inflammation, like colitis, multiple sclerosis, systemic sclerosis, lupus erythematodes, and arthritis with a focus on animal models supported by human data. A theory of the contribution of the SNS in chronic inflammation will be presented that spans these disease entities. One major finding is the biphasic nature of the sympathetic contribution to inflammation, with proinflammatory effects until the point of disease outbreak and mainly anti-inflammatory influence thereafter. Since sympathetic nerve fibers are lost from sites of inflammation during inflammation, local cells and immune cells achieve the capability to endogenously produce catecholamines to fine-tune the inflammatory response independent of brain control. On a systemic level, it has been shown across models that the SNS is activated in inflammation as opposed to the parasympathetic nervous system. Permanent overactivity of the SNS contributes to many of the known disease sequelae. One goal of neuroendocrine immune research is defining new therapeutic targets. In this respect, it will be discussed that at least in arthritis, it might be beneficial to support β-adrenergic and inhibit α-adrenergic activity besides restoring autonomic balance. Overall, in the clinical setting, we now need controlled interventional studies to successfully translate the theoretical knowledge into benefits for patients.

To protect or to kill: A persisting Darwinian immune dilemma

The immune system, which evolved as a protective system, can paradoxically mediate lethal effects when it is over-activated. These effects can be traced back to infected insects and are mainly mediated by phylogenetically old cytokines that have been found already in starfishes and sponges. We hypothesize that these anti-homeostatic effects are important for restricting the cumulative risk of transmission of highly mutating environmental pathogens that may endanger species, particularly when they start to originate and expand. Considering the Darwinian view that evolution is a permanent process, this anti-homeostatic program is preserved and expressed even when there is no risk for the species. Here, we review these aspects and discuss how evolutionary-imposed anti-homeostatic immune programs are expressed during acute and chronic human diseases, which can be further aggravated in the absence of medical interventions. The relevance of early identification of ancestral biomarkers that predict a shift from protective to deleterious immune outcomes is emphasized.

Systemic Lupus Erythematosus in Children and Young People

PURPOSE OF REVIEW

Juvenile-onset systemic lupus erythematosus ((j)SLE) is an autoimmune/inflammatory disease that results in significant damage and disability. When compared to patients with disease onset in adulthood, jSLE patients exhibit increased disease activity, damage and require more aggressive treatments. This manuscript summarises age-specific pathogenic mechanisms and underscores the need for age group-specific research, classification and treatment.

RECENT FINDINGS

Genetic factors play a significant role in the pathophysiology of jSLE, as > 7% of patients develop disease as a result of single gene mutations. Remaining patients carry genetic variants that are necessary for disease development, but require additional factors. Increased 'genetic impact' likely contributes to earlier disease onset and more severe phenotypes. Epigenetic events have only recently started to be addressed in jSLE, and add to the list of pathogenic mechanisms that may serve as biomarkers and/or treatment targets. To allow meaningful and patient-oriented paediatric research, age-specific classification criteria and treatment targets require to be defined as currently available tools established for adult-onset SLE have limitations in the paediatric cohort. Significant progress has been made in understanding the pathophysiology of jSLE. Meaningful laboratory and clinical research can only be performed using age group-specific tools, classification criteria and treatment targets.

Toward the Existence of a Sympathetic Neuroplasticity Adaptive Mechanism Influencing the Immune Response. A Hypothetical View-Part I

The nervous system exerts a profound influence on the function of the immune system (IS), mainly through the sympathetic arm of the autonomic nervous system. In fact, the sympathetic nervous system richly innervates secondary lymphoid organs (SLOs) such as the spleen and lymph nodes. For decades, different research groups working in the field have consistently reported changes in the sympathetic innervation of the SLOs during the activation of the IS, which are characterized by a decreased noradrenergic activity and retraction of these fibers. Most of these groups interpreted these changes as a pathological phenomenon, referred to as "damage" or "injury" of the noradrenergic fibers. Some of them postulated that this "injury" was probably due to toxic effects of released endogenous mediators. Others, working on animal models of chronic stimulation of the IS, linked it to the very chronic nature of processes. Unlike these views, this first part of the present work reviews evidence which supports the hypothesis of a specific adaptive mechanism of neural plasticity from sympathetic fibers innervating SLOs, encompassing structural and functional changes of noradrenergic nerves. This plasticity mechanism would involve segmental retraction and degeneration of these fibers during the activation of the IS with subsequent regeneration once the steady state is recovered. The candidate molecules likely to mediate this phenomenon are also here introduced. The second part will extend this view as to the potential changes in sympathetic innervation likely to occur in inflamed non-lymphoid peripheral tissues and its possible immunological implications.

Glucocorticoids and sympathetic neurotransmitters modulate the acute immune response to Trypanosoma cruzi

Evidence suggests that natural and adaptive immune responses can trigger neuroendocrine responses. Here, we discuss changes in the activity of the hypothalamus-pituitary-adrenal axis and in autonomic nerves, predominantly of the sympathetic nervous system, in a mouse model of acute infection with Trypanosoma cruzi. The endocrine response includes a marked increased release of glucocorticoid and a decrease of immune-stimulatory hormones, such as dehydroepiandrosterone sulfate, prolactin, and growth hormone during infection. These endocrine changes result in reduced proinflammatory cytokine production, increased regulatory/effector T cell ratio, and thymus atrophy. The sympathetic activity in the spleen of infected mice is also markedly reduced. However, the residual sympathetic activity can modulate the immune response to the parasite, as shown by increased mortality and production of proinflammatory cytokines in sympathetically denervated, infected mice. The outcome of the neuroendocrine response is the moderation of the intensity of the immune response to the parasite, an effect that results in delayed mortality in susceptible mice, and favors the course toward chronicity in more resistant animals.

Sympathetic Nerve Hyperactivity in the Spleen: Causal for Nonpathogenic-Driven Chronic Immune-Mediated Inflammatory Diseases (IMIDs)?

Immune-Mediated Inflammatory Diseases (IMIDs) is a descriptive term coined for an eclectic group of diseases or conditions that share common inflammatory pathways, and for which there is no definitive etiology. IMIDs affect the elderly most severely, with many older individuals having two or more IMIDs. These diseases include, but are not limited to, type-1 diabetes, obesity, hypertension, chronic pulmonary disease, coronary heart disease, inflammatory bowel disease, and autoimmunity, such as rheumatoid arthritis (RA), Sjőgren's syndrome, systemic lupus erythematosus, psoriasis, psoriatic arthritis, and multiple sclerosis. These diseases are ostensibly unrelated mechanistically, but increase in frequency with age and share chronic systemic inflammation, implicating major roles for the spleen. Chronic systemic and regional inflammation underlies the disease manifestations of IMIDs. Regional inflammation and immune dysfunction promotes targeted end organ tissue damage, whereas systemic inflammation increases morbidity and mortality by affecting multiple organ systems. Chronic inflammation and skewed dysregulated cell-mediated immune responses drive many of these age-related medical disorders. IMIDs are commonly autoimmune-mediated or suspected to be autoimmune diseases. Another shared feature is dysregulation of the autonomic nervous system and hypothalamic pituitary adrenal (HPA) axis. Here, we focus on dysautonomia. In many IMIDs, dysautonomia manifests as an imbalance in activity/reactivity of the sympathetic and parasympathetic divisions of the autonomic nervous system (ANS). These major autonomic pathways are essential for allostasis of the immune system, and regulating inflammatory processes and innate and adaptive immunity. Pathology in ANS is a hallmark and causal feature of all IMIDs. Chronic systemic inflammation comorbid with stress pathway dysregulation implicate neural-immune cross-talk in the etiology and pathophysiology of IMIDs. Using a rodent model of inflammatory arthritis as an IMID model, we report disease-specific maladaptive changes in β₂-adrenergic receptor (AR) signaling from protein kinase A (PKA) to mitogen activated protein kinase (MAPK) pathways in the spleen. Beta₂-AR signal "shutdown" in the spleen and switching from PKA to G-coupled protein receptor kinase (GRK) pathways in lymph node cells drives inflammation and disease advancement. Based on these findings and the existing literature in other IMIDs, we present and discuss relevant literature that support the hypothesis that unresolvable immune stimulation from chronic inflammation leads to a maladaptive disease-inducing and perpetuating sympathetic response in an attempt to maintain allostasis. Since the role of sympathetic dysfunction in IMIDs is best studied in RA and rodent models of RA, this IMID is the primary one used to evaluate data relevant to our hypothesis. Here, we review the relevant literature and discuss sympathetic dysfunction as a significant contributor to the pathophysiology of IMIDs, and then discuss a novel target for treatment. Based on our findings in inflammatory arthritis and our understanding of common inflammatory process that are used by the immune system across all IMIDs, novel strategies to restore SNS homeostasis are expected to provide safe, cost-effective approaches to treat IMIDs, lower comorbidities, and increase longevity.

The sympathetic nervous system affects the susceptibility and course of Trypanosoma cruzi infection

Trypanosoma cruzi (T. cruzi) is an intracellular parasite that causes Chagas' disease, a major health problem in Latin America. Using a murine model of infection with this parasite, we have previously shown that corticosterone blood levels are markedly elevated during the course of the disease in C57Bl/6 male mice and that this increase is protective for the host by restricting the production of pro-inflammatory cytokines. Since the hypothalamus-pituitary-adrenal (HPA) axis usually operates in a concerted way with the sympathetic nervous system (SNS), we have now studied whether noradrenergic nerves can affect the course of T. cruzi infection and the sexual dimorphism observed in the disease. We found a decreased splenic noradrenaline concentration and content, paralleled by a reduction in noradrenergic nerve fibers in the spleen of infected mice, and increased HPA axis activity. These alterations were more marked in males than in females. When the spontaneous loss of noradrenergic nerve fibers was advanced by chemical sympathectomy prior to infection, males died earlier and mortality significantly increased in females. Chemical denervation did not significantly affect the concentration of specific IgM and IgG_2a antibodies to T. cruzi, and did not worsen myocarditis, but resulted in increased parasitemia and IL-6 and IFN-γ blood levels. The results obtained in this model of parasitic disease provide further indications of the relevance of interactions between the immune system and the SNS for host defense.

Inhibition of catecholamine degradation ameliorates while chemical sympathectomy aggravates the severity of acute Friend retrovirus infection in mice

Several lines of evidence indicate that the sympathetic nervous system (SNS) might be involved in the pathogenesis and progression of retroviral infections. However, experimental data are scarce and findings inconsistent. Here, we investigated the role of the SNS during acute infection with Friend virus (FV), a pathogenic murine retrovirus that causes polyclonal proliferation of erythroid precursor cells and splenomegaly in adult mice. Experimental animals were infected with FV complex, and viral load, spleen weight, and splenic noradrenaline (NA) concentration was analyzed until 25 days post infection. Results show that FV infection caused a massive but transient depletion in splenic NA during the acute phase of the disease. At the peak of the virus-induced splenomegaly, splenic NA concentration was reduced by about 90% compared to naïve uninfected mice. Concurrently, expression of the catecholamine degrading enzymes monoamine oxidase A (MAO-A) and catechol-O-methyltransferase (COMT) was significantly upregulated in immune cells of the spleen. Pharmacological inhibition of MAO-A and COMT by the selective inhibitors clorgyline and 3,5-dinitrocatechol, respectively, efficiently blocked NA degradation and significantly reduced viral load and virus-induced splenomegaly. In contrast, chemical sympathectomy prior to FV inoculation aggravated the acute infection and extended the duration of the disease. Together these findings demonstrate that catecholamine availability at the site of viral replication is an important factor affecting the course of retroviral infections.

The sympathetic nervous system modulates CD4(+)Foxp3(+) regulatory T cells via noradrenaline-dependent apoptosis in a murine model of lymphoproliferative disease

The sympathetic nervous system (SNS) plays a crucial role in the course and development of autoimmune disease in Fas-deficient lpr/lpr mice. As regulatory T cells (Tregs) are considered important modulators of autoimmune processes, we analyzed the interaction between the SNS and Tregs in this murine model of lymphoproliferative disease. We found that the percentage of Tregs among CD4(+) T cells is increased in the spleen, lymph nodes, and thymus of lpr/lpr mice as compared to age-matched C57Bl/6J (B6) mice. Furthermore, noradrenaline (NA), the main sympathetic neurotransmitter, induced apoptosis in B6- and lpr/lpr-derived Tregs. NA also reduced the frequency of Foxp3(+) cells and Foxp3 mRNA expression via β2-adrenoceptor (β2-AR)-mediated mechanisms in a concentration and time-dependent manner. Destruction of peripheral sympathetic nerves by 6-hydroxydopamine significantly increased the percentage of Tregs in B6 control mice to an extent comparable to aged-matched lpr/lpr mice. The concentration of splenic NA negatively correlated with the frequency of CD4(+)Foxp3(+) Tregs. Additionally, 60days after sympathectomy, a partial recovery of NA concentrations led to Treg percentages comparable to those of intact, vehicle-treated controls. Immunohistochemical analysis of the spleen revealed localization of single Foxp3(+) Tregs in proximity to NA-producing nerve fibers, providing an interface between Tregs and the SNS. Taken together, our data suggest a relation between the degree of splenic sympathetic innervation and the size of the Treg compartment. While there are few examples of endogenous substances capable of affecting Tregs, our results provide a possible explanation of how the magnitude of the Treg compartment in the spleen can be regulated by the SNS.

Autonomic regulation of cellular immune function

The nervous system and the immune system (IS) are two integrative systems that work together to detect threats and provide host defense, and to maintain/restore homeostasis. Cross-talk between the nervous system and the IS is vital for health and well-being. One of the major neural pathways responsible for regulating host defense against injury and foreign antigens and pathogens is the sympathetic nervous system (SNS). Stimulation of adrenergic receptors (ARs) on immune cells regulates immune cell development, survival, proliferative capacity, circulation, trafficking for immune surveillance and recruitment, and directs the cell surface expression of molecules and cytokine production important for cell-to-cell interactions necessary for a coordinated immune response. Finally, AR stimulation of effector immune cells regulates the activational state of immune cells and modulates their functional capacity. This review focuses on our current understanding of the role of the SNS in regulating host defense and immune homeostasis. SNS regulation of IS functioning is a critical link to the development and exacerbation of chronic immune-mediated diseases. However, there are many mechanisms that need to be further unraveled in order to develop sound treatment strategies that act on neural-immune interaction to resolve or prevent chronic inflammatory diseases, and to improve health and quality of life.

Prevention of Mammary Tumor Development through Neuroimmunomodulation in the Spleen and Lymph Nodes of Old Female Sprague-Dawley Rats by L-Deprenyl

BACKGROUND

Development of mammary tumors is an age-associated phenomenon that is likely due to deficits in the neuroendocrine-immune interactions. Previously, we demonstrated that L-deprenyl, a monoamine oxidase-B (MAO-B) inhibitor, can enhance immune responses and restore noradrenergic (NA) innervation in the spleens of rats with carcinogen-induced and spontaneously developing mammary tumors.

OBJECTIVES

To investigate whether (1) treatment of early middle-aged female rats would prevent the spontaneous development of mammary tumors accompanied by restoration of immunity in the spleen and draining lymph nodes (DLN) and sympathetic NA innervation in the spleen and (2) deprenyl can influence the proliferation of estrogen receptor (ER)-positive (MCF-7 and T47D) and ER-negative (MDA-MB-231 and Hs 578T) human breast cancer cells.

METHODS

Early middle-aged (8- to 9-month-old) female Sprague-Dawley rats were treated with 0, 1.0 or 2.5 mg of deprenyl/kg body weight (BW) daily i.p. for 12 months. Cells of ER-positive (ER+) and ER-negative (ER-) human breast cancer cell lines were incubated with media or 10(-3) to 10(-8) M deprenyl for 1, 2, 4 or 6 days to examine the proliferation of cells.

RESULTS

Tumor incidence increased in saline-treated old female rats, while deprenyl treatment significantly reduced the incidence of mammary tumors in these rats. Saline-treated tumor-bearing rats exhibited reduced splenic NA innervation and norepinephrine (NE) content, splenic interleukin (IL)-2 and interferon (IFN)-γ levels and NK cell activity as well as DLN IL-2 and IFN-γ levels compared to young female rats without tumors. In contrast, treatment with 2.5 mg/kg of deprenyl enhanced IL-2 and IFN-γ production in both the spleen and DLN as well as splenic natural killer (NK) cell activity. Deprenyl treatment also increased concanavalin A (Con A)-induced proliferation of T lymphocytes in the DLN. Deprenyl-induced changes in immune responses were accompanied by enhanced NA innervation and NE content in the spleen. In vitro incubation of various concentrations of deprenyl with ER+ human breast cancer cell lines partly inhibited the proliferation of cells, while it had no effect on the ER- breast cancer cells.

CONCLUSIONS

These results suggest that (1) development of mammary tumors is mediated through the loss of immunity and sympathetic NA nerve fibers accompanied by reduced NE levels in the spleen, (2) the prevention of mammary tumor development by deprenyl may involve the reversal of the tumor-associated decline in sympathetic NA activity and cell-mediated immune responses in the spleen and DLN and (3) the antitumor effects of deprenyl may be partially mediated through ER-dependent intracellular signaling pathways.

Different peripheral neuroendocrine responses to Trypanosoma cruzi infection in mice lacking adaptive immunity

Trypanosoma cruzi infection in mice triggers neuroendocrine responses that affect the course of the disease. To analyze the contribution of adaptive immunity to these responses, comparative studies between normal C57Bl/6J and recombinase activator gene 1 (RAG-1)-deficient mice, which lack mature B and T lymphocytes, were performed. There was no difference between both types of mice in basal body weight. Following infection, higher parasitemia, increased IL-1β and IL-6 blood levels, less marked changes in lymphoid organs weight, no cardiomegaly, and earlier mortality were observed in RAG-1-deficient, compared with normal mice. The response of the hypothalamus-pituitary-adrenal axis after infection occurred earlier and was more intense in RAG-1-deficient mice than in normal mice. Noradrenaline concentration and serotonergic metabolism in the spleen, lymph nodes, and heart differed between RAG-1-deficient and normal mice. Our studies indicate that the absence of adaptive immunity to T. cruzi influences the neuroendocrine response to the infection with this parasite.

Underlying mechanisms of cAMP- and glucocorticoid-mediated inhibition of FasL expression in activation-induced cell death

Glucocorticoids (GCs) and cAMP-dependent signaling pathways exert diverse and relevant immune regulatory functions, including a tight control of T cell death and homeostasis. Both of these signaling molecules inhibit TCR-induced cell death and FasL expression, but the underlying mechanisms are still poorly understood. Therefore, to address this question, we performed a comprehensive screening of signaling pathways downstream of the TCR, in order to define which of them are targets of cAMP- and GC-mediated inhibition. We found that cAMP inhibited NF-κB and ERK pathways through a PKA-dependent mechanism, while Dexamethasone blocked TCR-induced NF-κB signaling. Although GCs and cAMP inhibited the induction of endogenous FasL mRNA expression triggered by TCR activation, they potentiated TCR-mediated induction of FasL promoter activity in transient transfection assays. However, when the same FasL promoter was stably transfected, the facilitatory effect of GCs and cAMP became inhibitory, thus resembling the effects on endogenous FasL mRNA expression. Hence, the endogenous chromatinization status known to occur in integrated or genomic vs. episomic DNA might be critical for proper regulation of FasL expression by cAMP and GCs. Our results suggest that the chromatinization status of the FasL promoter may function as a molecular switch, controlling cAMP and GC responsiveness and explaining why these agents inhibit FasL expression in T cells but induce FasL in other cell types.

The role of the sympathetic nervous system in the thymus in health and disease

The existence of a network of immunoneuroendocrine interactions that results in the reciprocal modulation of the classical functions of each system is well established at present. Most of the evidence derives from studies on secondary lymphoid organs, such as the spleen and lymph nodes. In this article, several aspects relevant to understand the role of the sympathetic nervous system in the establishment of these interactions in the thymus are discussed. At present, the sympathetic innervation of the thymus, the expression of adrenergic receptors in thymic cells, particularly of β-adrenergic receptors, and the effect of sympathetic neurotransmitters, although mainly derived from in vitro or pharmacological studies, seem to be relatively well studied. However, other aspects, such as the relevance that immune-sympathetic interactions at the thymic level may have for certain diseases, specially autoimmune or other diseases that primarily involve the activation of the immune system, as well as how the integration of sympathetic and hormonal signals at local levels may affect thymic functions, certainly deserve further investigation.

Stress hormones collaborate to induce lymphocyte apoptosis after high level spinal cord injury

Post-traumatic immune suppression renders individuals with spinal cord injury (SCI) susceptible to infection. Normally, proper immune function is regulated by collaboration between the sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis and involves the controlled release of glucocorticoids (GCs) and norepinephrine (NE). Recently, we showed that after high thoracic (T3) SCI, aberrant levels of GCs and NE accumulate in the blood and spleen, respectively. These changes are associated with splenic atrophy, splenic leucopenia, increased intrasplenic caspase 3 levels, and suppressed B lymphocyte function. As GCs boost SNS function, in part by increasing the expression and affinity of beta2 adrenergic receptors (beta2ARs) while simultaneously preventing beta2AR down-regulation, we predicted that surges in stress hormones (i.e., GCs and NE) in the blood and spleen of mice with high-level SCI would act concurrently to adversely affect lymphocyte function and survival. Here, we show that post-SCI concentrations of GCs enhance the sensitivity of lymphocytes to beta2AR stimulation causing an increase in intracellular Bcl-2 interacting mediator of cell death (Bim) and subsequent apoptosis. In vivo, the combined antagonism of GC receptors and beta2ARs significantly diminished lymphocyte Bim levels and SCI-induced splenic lymphopenia. Together, these data suggest that pharmacological antagonists of the HPA/SNS axes should be considered as adjunct therapies for ameliorating post-traumatic immune suppression in quadriplegics and high paraplegics.

Beta1-adrenergic receptors on immune cells impair innate defenses against Listeria

Cold restraint (CR) for 1 h elicits a psychological and physiological stress that inhibits host defenses against Listeria monocytogenes (LM). Previous analyses indicated that this inhibition is not due to depletion of B or T cells but is instead dependent on signaling through beta-adrenoceptors (betaARs). We now show that impaired host resistance by CR cannot be accounted for by a decrease in LM-specific (listeriolysin O(91-99) tetramer(+)) effector CD8(+) T cells; this result is consistent with previous observations that CR-induced effects are mainly limited to early anti-LM responses. beta2-Adrenoceptor (beta2AR)(-/-) FVB/NJ and wild-type FVB/NJ mice had equivalent anti-LM defenses, whereas beta1-adrenoceptor (beta1AR)(-/-) FVB/NJ mice had lower levels of LM even when subjected to CR treatment. Additionally, host-resistance competency of beta1AR(-/-) mice could be transferred to irradiated wild-type mice reconstituted with beta1AR(-/-) bone marrow progenitors and spleen cells, indicating that beta1AR signaling on immune cells reduces anti-LM responses. beta1AR(-/-) mice had improved cellular (delayed-type hypersensitivity) responses while beta2AR(-/-) mice had improved humoral responses (IgG1, IgG2, and IgM), a result that further explains the strain differences in LM defenses. CR-induced expression of beta1AR and beta2AR mRNA was assessed by real-time PCR. CR treatment significantly increased betaAR mRNAs in Ficoll-purified and F4/80(+)-enhanced liver but not splenic homogenates, demonstrating an organ-specific effect of stress that alters host defenses. Finally, CR treatment induced early increases in perforin expression that may enhance immune cell apoptosis and interfere with LM clearance. In conclusion, beta1AR signaling has immunomodulatory effects on early cell-mediated immune responses; a lack of beta1AR signaling improves antilisterial defenses and cell-mediated immunity, in general.

Perspective is everything: an irreverent discussion of CNS-immune system interactions as viewed from different scientific traditions

The immune system is a host defense system comprised of both innate mechanisms able to rapidly recognize and respond to conserved pathogen associated molecular patterns (PAMPs) as well as adaptive mechanisms able to respond to a wide variety of non-conserved and conserved pathogen associated molecules. In vitro and in vivo studies have demonstrated that the kinetics and type of immune response triggered by pathogenic insults is a function of both the nature of the insult and the subsequent cross-regulatory interactions between the responding immune cells. In this context, the potential immunomodulatory influences of the nervous system have been often viewed as exerting minimal modulatory effects and thus of being largely irrelevant in the development of immune responses. Here, using a Saturday Night Live (SNL)-styled point:counterpoint format, we discuss whether and to what extent the nervous system can shape the responses of the immune system. Finally, we examine whether primary degenerative disorders of the CNS are likely to lead to alterations in immune function.

Conversation galante: how the immune and the neuroendocrine systems talk to each other

The generation of endogenous adjuvants and the clearance of apoptotic cells occur at the intersection between the neuroendocrine and the immune systems. Recent data suggest that autoimmunity associates with a communication breakdown between the two systems and that events taking place in lymphoid organs and in peripheral inflamed tissues shape the response to tissue damage. Autonomic nerve endings release norepinephrine and acetylcholine, whereas sensitive fibers release neuropeptides. Moreover, nervous endings in the tissues control the secretory activity of neuroendocrine cells, which are distributed in the gut, the pancreas, the lung, the thyroid, the liver, the prostate, the skin. Intracellular enzymes, and in particular the 11 beta-hydroxysteroid dehydrogenase type 1, regulate the availability of active glucocorticoids in inflammatory macrophages and maturing dendritic cells; in turn the rate of active glucocorticoids determine the efficiency of phagocytes in clearing apoptotic cells, possibly influencing the availability of autoantigens. Immune cells release cytokines, which, in turn signal to the central and peripheral nervous system. We learnt from cytokine-neutralizing therapies that the sustained production of pro-inflammatory signals interferes with various neuro-endocrine axes. A better molecular dissection of this finely regulated inter-system cross-talk, in physiological conditions and during self-sustaining inflammatory diseases, might enable more rational therapeutic approaches.

Physiology of psychoneuroimmunology: a personal view

This article offers a personal view on how the concept of the existence of a network of immune-neuro-endocrine interactions has evolved in the last 30 years. The main topic addressed is the relevance of the exchange of signals between the immune, endocrine and nervous systems for immunoregulation and brain functions. Particular emphasis is given to circuits involving immune cell products, the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system. The operation of these circuits can affect immune functions and the course of inflammatory, autoimmune and infectious diseases. We also discuss increasing evidence that brain-born cytokines play an important role in brain physiology and in the integration of the immune-neuro-endocrine network.