Sympathetic neurotransmitters in joint inflammation

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

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

The Neuroimmune Interplay in Joint Pain: The Role of Macrophages

Chronic pain associated with joint disorders, such as rheumatoid arthritis (RA), osteoarthritis (OA) and implant aseptic loosening (AL), is a highly debilitating symptom that impacts mobility and quality of life in affected patients. The neuroimmune crosstalk has been demonstrated to play a critical role in the onset and establishment of chronic pain conditions. Immune cells release cytokines and immune mediators that can activate and sensitize nociceptors evoking pain, through interaction with receptors in the sensory nerve terminals. On the other hand, sensory and sympathetic nerve fibers release neurotransmitters that bind to their specific receptor expressed on surface of immune cells, initiating an immunomodulatory role. Macrophages have been shown to be key players in the neuroimmune crosstalk. Moreover, macrophages constitute the dominant immune cell population in RA, OA and AL. Importantly, the targeting of macrophages can result in anti-nociceptive effects in chronic pain conditions. Therefore, the aim of this review is to discuss the nature and impact of the interaction between the inflammatory response and nerve fibers in these joint disorders regarding the genesis and maintenance of pain. The role of macrophages is highlighted. The alteration in the joint innervation pattern and the inflammatory response are also described. Additionally, the immunomodulatory role of sensory and sympathetic neurotransmitters is revised.

Inhibition of Spinal Interleukin-33 Attenuates Peripheral Inflammation and Hyperalgesia in Experimental Arthritis

Accumulating evidence indicates that the continuous and intense nociceptive from inflamed tissue may increase the excitability of spinal dorsal horn neurons, which can signal back and modulate peripheral inflammation. Previous studies have demonstrated that spinal interleukin (IL)-33 contributes to the hyperexcitability of spinal dorsal horn neurons. This study was undertaken to investigate whether spinal IL-33 can also influence a peripheral inflammatory response in a rat model of arthritis. Lentivirus-delivered short hairpin RNA targeting IL-33 (LV-shIL-33) was constructed for gene silencing. Rats with adjuvant-induced arthritis (AIA) were injected intrathecally with LV-shIL-33 3 days before the complete Freund's adjuvant (CFA) injection. During an observation period of 21 days, pain-related behavior and inflammation were assessed. In addition, the expression of spinal proinflammatory cytokines and the activation of spinal extracellular signal-regulated kinase (ERK) and nuclear factor-κB (NF-κB) pathways were evaluated on 9 days after CFA treatment. The existence of tissue injury or inflammation in rats with AIA resulted in the upregulation of spinal IL-33, which is predominantly expressed in neurons, astrocytes, and oligodendrocytes. Intrathecal administration of LV-shIL-33 significantly alleviated hyperalgesia, paw swelling, and joint destruction, and attenuated the expression of proinflammatory cytokines [IL-6, IL-1β, and tumor necrosis factor-α (TNF-α)], as well as the activation of ERK and NF-κB/p65 in the spinal cord. Our data suggest that spinal IL-33 contributes to the development of both peripheral inflammation and hyperalgesia. Thus, interference with IL-33 at the spinal level might represent a novel therapeutic target for painful inflammatory disorders.

Immune and Epigenetic Pathways Linking Childhood Adversity and Health Across the Lifespan

Childhood adversity is associated with a host of mental and physical health problems across the lifespan. Individuals who have experienced childhood adversity (e.g., child abuse and neglect, family conflict, poor parent/child relationships, low socioeconomic status or extreme poverty) are at a greater risk for morbidity and premature mortality than those not exposed to childhood adversity. Several mechanisms likely contribute to the relationship between childhood adversity and health across the lifespan (e.g., health behaviors, cardiovascular reactivity). In this paper, we review a large body of research within the field of psychoneuroimmunology, demonstrating the relationship between early life stress and alterations of the immune system. We first review the literature demonstrating that childhood adversity is associated with immune dysregulation across different indices, including proinflammatory cytokine production (and its impact on telomere length), illness and infection susceptibility, latent herpesvirus reactivation, and immune response to a tumor. We then summarize the growing literature on how childhood adversity may alter epigenetic processes. Finally, we propose future directions related to this work that have basic and applied implications.

Immunopathophysiology of Juvenile Spondyloarthritis (jSpA): The "Out of the Box" View on Epigenetics, Neuroendocrine Pathways and Role of the Macrophage Migration Inhibitory Factor (MIF)

Juvenile spondyloarthritis (jSpA) is a an umbrella term for heterogeneous group of related seronegative inflammatory disorders sharing common symptoms. Although it mainly affects children and adolescents, it often remains active during adulthood. Genetic and environmental factors are involved in its occurrence, although the exact underlying immunopathophysiology remains incompletely elucidated. Accumulated evidence suggests that, in affected patients, subclinical gut inflammation caused by intestinal dysbiosis, is pivotal to the future development of synovial-entheseal complex inflammation. While the predominant role of IL17/23 axis, TNF-α, and IL-7 in the pathophysiology of SpA, including jSpA, is firmly established, the role of the cytokine macrophage migration inhibitory factor (MIF) is generally overlooked. The purpose of this review is to discuss and emphasize the role of epigenetics, neuroendocrine pathways and the hypothalamic-pituitary (HPA) axis, and to propose a novel hypothesis of the role of decreased NLRP3 gene expression and possibly MIF in the early phases of jSpA development. The decreased NLRP3 gene expression in the latter, due to hypomethylation of promotor site, is (one of) the cause for inflammasome malfunction leading to gut dysbiosis observed in patients with early jSpA. In addition, we highlight the role of MIF in the complex innate, adaptive cellular and main effector cytokine network, Finally, since treatment of advanced bone pathology in SpA remains an unmet clinical need, I suggest possible new drug targets with the aim to ultimately improve treatment efficacy and long-term outcome of jSpA patients.

Driving β2- While Suppressing α-Adrenergic Receptor Activity Suppresses Joint Pathology in Inflammatory Arthritis

Objective

Hypersympathetic activity is prominent in rheumatoid arthritis, and major life stressors precede onset in ~80% of patients. These findings and others support a link between stress, the sympathetic nervous system and disease onset and progression. Here, we extend previous research by evaluating how selective peripherally acting α/β2-adrenergic drugs affect joint destruction in adjuvant-induced arthritis.

Methods

Complete Freund's adjuvant induced inflammatory arthritis in male Lewis rats. Controls received no treatment. Arthritic rats then received vehicle or twice-daily treatment with the α-adrenergic antagonist, phentolamine (0.5 mg/day) and the β2-adrenergic agonist, terbutaline (1200 µg/day, collectively named SH1293) from day (D) of disease onset (D12) through acute (D21) and severe disease (D28). Disease progression was assessed in the hind limbs using dorsoplantar widths, X-ray analysis, micro-computed tomography, and routine histology on D14, D21, and D28 post-immunization.

Results

On D21, SH1293 significantly attenuated arthritis in the hind limbs, based on reduced lymphocytic infiltration, preservation of cartilage, and bone volume. Pannus formation and sympathetic nerve loss were not affected by SH1293. Bone area and osteoclast number revealed high- and low-treatment-responding groups. In high-responding rats, treatment with SH1293 significantly preserved bone area and decreased osteoclast number, data that correlated with drug-mediated joint preservation. SH1293 suppressed abnormal bone formation based on reduced production of osteophytes. On D28, the arthritic sparing effects of SH1293 on lymphocytic infiltration, cartilage and bone sparing were maintained at the expense of bone marrow adipocity. However, sympathetic nerves were retracted from the talocrural joint.

Conclusion and Significance

Our findings support a significant delay in early arthritis progression by treatment with SH1293. Targeting sympathetic neurotransmission may provide a strategy to slow disease progression.

Divergence of neuroimmune circuits activated by afferent and efferent vagal nerve stimulation in the regulation of inflammation

KEY POINTS

It has previously been shown that afferent and efferent vagal nerve stimulation potently inhibits lipopolysaccharide (LPS)-induced inflammation Our data show inhibition of inflammation by efferent but not afferent vagal nerve stimulation requires T-cell derived acetylcholine We show that afferent and efferent neuroimmune circuits require β₂ -adrenergic receptor signalling ABSTRACT: Chronic inflammation due to inappropriate immune cell activation can have significant effects on a variety of organ systems, reducing lifespan and quality of life. As such, highly targeted control of immune cell activation is a major therapeutic goal. Vagus nerve stimulation (VNS) has emerged as a therapeutic modality that exploits neuroimmune communication to reduce immune cell activation and consequently inflammation. Although vagal efferent fibres were originally identified as the primary driver of anti-inflammatory actions, the vagus nerve in most species of animals predominantly comprises afferent fibres. Stimulation of vagal afferent fibres can also reduce inflammation; it is, however, uncertain how these two neuroimmune circuits diverge. Here we show that afferent VNS induces a mechanism distinct from efferent VNS, ameliorating lipopolysaccharide (LPS)-induced inflammation independently of T-cell derived acetylcholine (ACh) which is required by efferent VNS. Using a β₂ -adrenergic receptor antagonist (β₂ -AR), we find that immune regulation induced by intact, afferent, or efferent VNS occurs in a β_2- AR-dependent manner. Together, our findings indicate that intact VNS activates at least two distinct neuroimmune circuits each with unique mechanisms of action. Selective targeting of either the vagal efferent or afferent fibres may provide more personalized, robust and effective control over inappropriate immune responses.

Role of adrenergic receptor signalling in neuroimmune communication

Neuroimmune communication plays a crucial role in maintaining homeostasis and promptly responding to any foreign insults. Sympathetic nerve fibres are innervated into all the lymphoid organs (bone marrow, thymus, spleen, and lymph nodes) and provide a communication link between the central nervous system (CNS) and ongoing immune response in the tissue microenvironment. Neurotransmitters such as catecholamines (epinephrine and norepinephrine) bind to adrenergic receptors present on most immune and non-immune cells, establish a local neuroimmune-communication system, and help regulate the ongoing immune response. The activation of these receptors varies with the type of receptor-activated, target cell, the activation status of the cells, and timing of activation. Activating adrenergic receptors, specifically β-adrenergic signalling in immune cells leads to activation of the cAMP-PKA pathway or other non-canonical pathways. It predominantly leads to immune suppression such as inhibition of IL-2 secretion and a decrease in macrophages phagocytosis. This review discusses the expression of different adrenergic receptors in various immune cells, signalling, and how it modulates immune cell function and contributes to health and diseases. Understanding the neuroimmune communication through adrenergic receptor signalling in immune cells could help to design better strategies to control inflammation and autoimmunity.

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Primary and secondary lymphoid organs are innervated with sympathetic nerve fibres.

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Adrenergic receptor expression on immune and non-immune cells establishes a local neuroimmune communication system.

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Adrenergic receptor signalling in immune cells controls the differentiation and function of various immune cells.

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Modulating adrenergic receptor signalling with a specific agonist or antagonist also affect the immune response.

Beyond neurotransmission: acetylcholine in immunity and inflammation

Acetylcholine (ACh) is best known as a neurotransmitter and was the first such molecule identified. ACh signalling in the neuronal cholinergic system has long been known to regulate numerous biological processes (reviewed by Beckmann and Lips). In actuality, ACh is a ubiquitous signalling molecule that is produced by numerous non-neuronal cell types and even by some single-celled organisms. Within multicellular organisms, a non-neuronal cholinergic system that includes the immune system functions in parallel with the neuronal cholinergic system. Several immune cell types both respond to ACh signals and can directly produce ACh. Recent work from our laboratory has demonstrated that the capacity to produce ACh is an intrinsic property of T cells responding to viral infection, and that this ability to produce ACh is dependent upon IL-21 signalling to the T cells. Furthermore, during infection this immune-derived ACh is necessary for the T cells to migrate into infected tissues. In this review, we will discuss the various sources of ACh that are relevant during immune responses and describe how ACh acts on immune cells to influence their functions. We will also address the clinical implications of this fascinating aspect of immunity, focusing on ACh's role in the migration of T cells during infection and cancer.

Marriage, divorce, and the immune system

This article reviews evidence from several lines of work to describe how marriage and divorce can provoke health-relevant immune alterations, including ways that marital closeness can be perilous for health and divorce can be beneficial. The multiple stresses of a troubled relationship are depressogenic, and the development of a mood disorder sets the stage for psychological and biological vulnerability. Depression provides a central pathway to immune dysregulation, inflammation, and poor health; gender-related differences in depression and inflammation can heighten risk for women compared to men. Sleep and obesity can simultaneously feed off depression as they promote it. In addition, spousal similarities in health behaviors, gene expression, immune profiles and the gut microbiota offer new ways to consider the health advantages and risks of marriage and divorce, providing new perspectives on couples' interdependence, as well as new directions for research. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Interplay between sympathetic nervous system and inflammation in aseptic loosening of hip joint replacement

Inflammation is a common symptom in joint disorders such as rheumatoid arthritis, osteoarthritis (OA) and implant aseptic loosening (AL). The sympathetic nervous system is well known to play a critical role in regulating inflammatory conditions, and imbalanced sympathetic activity has been observed in rheumatoid arthritis. In AL it is not clear whether the sympathetic nervous system is altered. In this study we evaluated the systemic and local profile of neuroimmune molecules involved in the interplay between the sympathetic nervous system and the periprosthetic inflammation in hip AL. Our results showed that periprosthetic inflammation does not trigger a systemic response of the sympathetic nervous system, but is mirrored rather by the impairment of the sympathetic activity locally in the hip joint. Moreover, macrophages were identified as key players in the local regulation of inflammation by the sympathetic nervous system in a process that is implant debris-dependent and entails the reduction of both adrenergic and Neuropetide Y (NPY)-ergic activity. Additionally, our results showed a downregulation of semaphorin 3A (SEMA3A) that may be part of the mechanism sustaining the periprosthetic inflammation. Overall, the local sympathetic nervous system emerges as a putative target to mitigate the inflammatory response to debris release and extending the lifespan of orthopedic implants.

Neuro- and nephroprotective effect of grape seed proanthocyanidin extract against carboplatin and thalidomide through modulation of inflammation, tumor suppressor protein p53, neurotransmitters, oxidative stress and histology

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Carboplatin and thalidomide induced neuro-nephrotoxicity.

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Carboplatin and thalidomide caused inflammation.

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Carboplatin and thalidomide upregulate tumor suppressor protein p53.

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Carboplatin and thalidomide disturbed cytokine production.

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Neuro-and nephroprotective effect of grape seed proanthocyanidin.

The combination of thalidomide and carboplatin is one of the most potent chemotherapeutic strategies for the treatment of cancer. However, limited studies have been conducted on the neurotoxicity and nephrotoxicity of both chemotherapeutic agents. The aim of our study was to assess the toxicity of thalidomide and carboplatin combination on brain and kidney and investigate the protective effect of grape seed proanthocyanidin extract (GSPE). Thalidomide and carboplatin induced up-regulation of the expression of p53, tumor necrosis factor-α and interleukin-6 in brain and kidney. Acetylcholinesterase, dopamine and serotonin were decreased and norepinephrine was increased. Thiobarbituric acid reactive substances, nitric oxide, lipid profile, bilirubin and creatinine were elevated, while antioxidants enzymes (GST, GPX, CAT and SOD), total antioxidant capacity and the levels of glutathione were decreased. A microscopic examination showed shrinkage of capillaries, degeneration with pyknotic nuclei, loss of normal structure and neuronal degeneration. GSPE co-treatment with thalidomide and carboplatin reduced their brain and renal damage, oxidative stress, diminished cytokines, p53, neurotransmitters and biochemical parameters, and inhibited brain and renal cell apoptosis. It can be concluded that, the protective effects of GSPE against thalidomide and carboplatin induced-brain and renal damage was associated with the minimization of oxidative stress.

An Evaluation of Perceived Health Risk and Depressive Symptoms Before a Disaster in Predicting Postdisaster Inflammation

OBJECTIVE

Exposure to major life stressors is associated with subsequent enhanced inflammation-related disease processes. Depressive symptoms exacerbate stress-induced inflammatory responses. Moreover, those who report a high degree of perceived health risk before being exposed to a major life stressor such as a disaster are at risk for poor health outcomes. The present study examined whether perceived health risk and depressive symptoms before a disaster were associated with postdisaster inflammation markers.

METHODS

The sample included 124 participants (mean [standard deviation] age = 55 [16] years; 69% women). At a baseline visit, participants completed self-report measures of perceived health risk and depressive symptoms (Center for Epidemiologic Studies Depression Scale) in addition to a blood draw for the assessment of inflammation markers (C-reactive protein, tumor necrosis factor receptor 1, and interleukin 6). All participants lived near a large petrochemical complex where an unexpected explosion occurred. A second blood sample was obtained 2 to 6 months after the explosion.

RESULTS

No significant differences in inflammation markers were found between predisaster and postdisaster assessment (p > .21). An interaction between predisaster perceived health risk and depressive symptoms in predicting postdisaster circulating inflammation markers was identified (Cohen f = 0.051). Specifically, predisaster perceived health risk was associated with postdisaster circulating inflammation markers if predisaster depressive symptoms were greater than 8.10 on the Center for Epidemiologic Studies Depression Scale.

CONCLUSIONS

These findings add to our understanding of the complex interactions between stress, depression, and immune responses. Indeed, findings provide a potential mechanism (i.e., inflammation) explaining the association between exposure to major life stressors and negative mental and physical health outcomes.

Future therapeutic targets in rheumatoid arthritis?

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by persistent joint inflammation. Without adequate treatment, patients with RA will develop joint deformity and progressive functional impairment. With the implementation of treat-to-target strategies and availability of biologic therapies, the outcomes for patients with RA have significantly improved. However, the unmet need in the treatment of RA remains high as some patients do not respond sufficiently to the currently available agents, remission is not always achieved and refractory disease is not uncommon. With better understanding of the pathophysiology of RA, new therapeutic approaches are emerging. Apart from more selective Janus kinase inhibition, there is a great interest in the granulocyte macrophage-colony stimulating factor pathway, Bruton's tyrosine kinase pathway, phosphoinositide-3-kinase pathway, neural stimulation and dendritic cell-based therapeutics. In this review, we will discuss the therapeutic potential of these novel approaches.

Probing the response of human osteoblasts following exposure to sympathetic neuron-like PC-12 cells in a 3D coculture model

Understanding the capacity of the sympathetic nervous system (SNS) to regulate bone homeostasis has implications for a number of metabolic diseases and may help establish connections between certain neurological conditions and bone quality. The goal of the present work was to gain a deeper understanding of the influence of the SNS on the phenotype of osteoblasts, a major cell type in bone. An in vitro coculture model with human osteoblasts and sympathetic-like, neuroendocrine pheochromocytoma-12 (PC-12) cells encapsulated within separate 3D poly(ethylene glycol) diacrylate (PEGDA) hydrogels was utilized to assess markers involved with bone ECM formation and osteoclast formation. In terms of bone ECM proteins, only osteopontin (OPN) was significantly increased in osteoblasts exposed to PC-12 cells relative to osteoblast mono-culture controls. In contrast, all bone resorption markers investigated (IL-6, TNF, IL-1β, VEGF-A) were enhanced at the gene level and the ratio of osteoprotegerin (OPG) to RANKL was significantly decreased in osteoblasts exposed to PC-12 cells. Cumulatively, these data indicate that the SNS may substantially influence bone resorption. Because of the context-dependent nature of the SNS, future studies will characterize the secretion profile of neurotransmitters and neuropeptides from the PC-12 cells in our model. Additionally, various SNS modulating pharmacologic agents will be examined for their capacity to reduce expression of bone resorption/inflammatory markers. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 984-990, 2017.

Norepinephrine modulates osteoarthritic chondrocyte metabolism and inflammatory responses

OBJECTIVE

Norepinephrine (NE) was measured in synovial fluid of trauma patients and sympathetic nerve fibers were detected in healthy and osteoarthritic (OA) joint tissues indicating that cartilage pathophysiology might be influenced by sympathetic neurotransmitters. The aim of this study was to elucidate the mostly unknown role of NE in OA chondrocyte metabolism and inflammatory responses.

METHODS

Articular cartilage was received after total knee replacement surgery from OA patients. Expression of adrenergic receptors (AR) and tyrosine hydroxylase (TH) was tested with end point polymerase chain reaction (PCR) and immunohistochemistry. 3-dimensional (3D) cell cultures were employed to analyze effects of NE on chondrocyte cell metabolism and the expression of interleukins (ILs), matrix metalloproteases (MMPs), tissue inhibitor of metalloproteases (TIMPs), glycosaminoglycan (GAG) and collagen II under non- and inflammatory conditions. Chondrocyte monolayer cultures were used to specify AR subtypes, to analyze cell cycle distribution and to determine catecholamines in cell culture supernatants.

RESULTS

AR subtypes and TH were detected in chondrocytes, whereas NE was not released in measurable amounts. 10(-6) M NE reversed IL-1β induced changes in IL-8, MMP-13, GAG and collagen II expression/production indicating for β-AR signaling. Additionally, NE caused cell cycle slow down and decreased proliferation via β-AR signaling. 10(-8) M NE increased the number of proliferating cells and induced apoptosis via α1-AR signaling.

CONCLUSIONS

NE affects chondrocytes from OA cartilage regarding inflammatory response and its cell metabolism in a dose dependent manner. The sympathetic nervous system (SNS) may have a dual function in OA pathology with preserving a stable chondrocyte phenotype via β-AR signaling and OA pathogenesis accelerating effects via α-AR signaling.

Progress in Sympathetically Mediated Pathological Pain

Aim of review

Many chronic pain conditions remain difficult to treat, presenting a high burden to society. Conditions such as complex regional pain syndrome may be maintained or exacerbated by sympathetic activity. Understanding the interactions between sympathetic nervous system and sensory system will help to improve the effective management of pathological pain including intractable neuropathic pain and persistent inflammatory pain.

Method

We first described the discovery of abnormal connections between sympathetic and sensory neurons. Subsequently, the functional roles of sympathetic sprouting in altered neuronal excitability and increased pain sensitivity were discussed. The mechanisms of the sympathetic sprouting were focusing on its relationship with neurotrophins, local inflammation, and abnormal spontaneous activity. Finally, we discussed clinical implications and conflicting findings in the laboratory and clinical research with respect to the interaction between sympathetic system and sensory system.

Recent findings

The findings that sprouting of sympathetic fibers into the sensory ganglia (dorsal root ganglion) after peripheral nerve injury, offers a possible explanation of the sympathetic involvement in pain. It is also suggested that releases of adenosine triphosphate (ATP), in addition to norepinephrine, from sympathetic nerve endings play important roles in sympathetic-mediated pain. New evidence indicates the importance of sympathetic innervation in local inflammatory responses.

Summary

Hopefully, this review will reinvigorate the study of sympathetic-sensory interactions in chronic pain conditions, and help to better understand how sympathetic system contributes to this serious clinical problem.

Modulation of peripheral inflammation by the spinal cord

The central nervous system, and the spinal cord in particular, is involved in multiple mechanisms that influence peripheral inflammation. Both pro- and anti-inflammatory feedback loops can involve just the peripheral nerves and spinal cord or can also include more complex, supraspinal structures such as the vagal nuclei and the hypothalamic-pituitary axis. Analysis is complicated by the fact that inflammation encompasses a constellation of end points from simple edema to changes in immune cell infiltration and pathology. Whether or not any of these individual elements is altered by any potential mechanism is determined by a complex algorithm including, but not limited to, chronicity of the inflammation, tissue type, instigating stimulus, and state/tone of the immune system. Accordingly, the pharmacology and anatomical substrate of spinal cord modulation of peripheral inflammation are discussed with regard to peripheral tissue type, inflammatory insult (initiating stimulus), and duration of the inflammation.

Neuroendocrine regulation of inflammation

The interaction between the sympathetic nervous system and the immune system has been documented over the last several decades. In this review, the neuroanatomical, cellular, and molecular evidence for neuroimmune regulation in the maintenance of immune homeostasis will be discussed, as well as the potential impact of neuroimmune dysregulation in health and disease.

Targeting α- and β-Adrenergic Receptors Differentially Shifts Th1, Th2, and Inflammatory Cytokine Profiles in Immune Organs to Attenuate Adjuvant Arthritis

The sympathetic nervous system (SNS) regulates host defense responses and restores homeostasis. SNS-immune regulation is altered in rheumatoid arthritis (RA) and rodent models of RA, characterized by nerve remodeling in immune organs and defective adrenergic receptor (AR) signaling to immune cell targets. The SNS typically promotes or suppresses inflammation via α- and β₂-AR activation, respectively, and indirectly drives humoral immunity by blocking Th1 cytokine secretion. Here, we investigate how β₂-AR stimulation and/or α-AR blockade at disease onset affects disease pathology and cytokine profiles in relevant immune organs from male Lewis rats with adjuvant-induced arthritis (AA). Rats challenged to induce AA were treated with terbutaline (TERB), a β₂-AR agonist (600 μg/kg/day) and/or phentolamine (PHEN), an α-AR antagonist (5.0 mg/kg/day) or vehicle from disease onset through severe disease. We report that in spleen, mesenteric (MLN) and draining lymph node (DLN) cells, TERB reduces proliferation, an effect independent of IL-2. TERB also fails to shift T helper (Th) cytokines from a Th1 to Th2 profile in spleen and MLN (no effect on IFN-γ) and DLN (greater IFN-γ) cells. In splenocytes, TERB, PHEN, and co-treatment (PT) promotes an anti-inflammatory profile (greater IL-10) and lowers TNF-α (PT only). In DLN cells, drug treatments do not affect inflammatory profiles, except PT, which raised IL-10. In MLN cells, TERB or PHEN lowers MLN cell secretion of TNF-α or IL-10, respectively. Collectively, our findings indicate disrupted β₂-AR, but not α-AR signaling in AA. Aberrant β₂-AR signaling consequently derails the sympathetic regulation of lymphocyte expansion, Th cell differentiation, and inflammation in the spleen, DLNs and MLs that is required for immune system homeostasis. Importantly, this study provides potential mechanisms through which reestablished balance between α- and β₂-AR function in the immune system ameliorates inflammation and joint destruction in AA.

Early-Life Stress and Adult Inflammation

The origins of modern psychology are deeply rooted in the notion that stressful early-life experiences negatively impact people’s mental health. Emerging work in the field of health psychology suggests that early-life stress also impacts physical well-being. Indeed, those who experienced severe early-life stress as children are more at risk for cardiovascular disease, type 2 diabetes, and cancer compared with those who did not have those early-life experiences. Recent work in the field of psychoneuroimmunology suggests that inflammation may be one mechanism underlying these associations. In this article, we provide a brief overview of the literature on early-life stress and inflammation and how psychological, autonomic, neuroendocrine, and epigenetic responses to the early environment lead to potentiated inflammation in adulthood. We conclude by highlighting the need for health-promotion and disease-prevention programs that are designed to reduce the frequency and severity of early-life stress.

Activation of spinal NF-κB/p65 contributes to peripheral inflammation and hyperalgesia in rat adjuvant-induced arthritis

OBJECTIVE

It is known that noxious stimuli from inflamed tissue may increase the excitability of spinal dorsal horn neurons (a process known as central sensitization), which can signal back and contribute to peripheral inflammation. However, the underlying mechanisms have yet to be fully defined. A number of recent studies have indicated that spinal NF-κB/p65 is involved in central sensitization, as well as pain-related behavior. Thus, the aim of this study was to determine whether NF-κB/p65 can facilitate a peripheral inflammatory response in rat adjuvant-induced arthritis (AIA).

METHODS

Lentiviral vectors encoding short hairpin RNAs that target NF-κB/p65 (LV-shNF-κB/p65) were constructed for gene silencing. The spines of rats with AIA were injected with LV-shNF-κB/p65 on day 3 or day 10 after treatment with Freund's complete adjuvant (CFA). During an observation period of 20 days, pain-related behavior, paw swelling, and joint histopathologic changes were evaluated. Moreover, the expression levels of spinal tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), and cyclooxygenase 2 (COX-2) were assessed on day 14 after CFA treatment.

RESULTS

The presence of peripheral inflammation in rats with AIA induced an increase in NF-κB/p65 expression in the spinal cord, mainly in the dorsal horn neurons and astrocytes. Delivery of LV-shNF-κB/p65 to the spinal cord knocked down the expression of NF-κB/p65 and significantly attenuated hyperalgesia, paw edema, and joint destruction. In addition, spinal delivery of LV-shNF-κB/p65 reduced the overexpression of spinal TNFα, IL-1β, and COX-2.

CONCLUSION

These findings indicate that spinal NF-κB/p65 plays an important role in the initiation and development of both peripheral inflammation and hyperalgesia. Thus, inhibition of spinal NF-κB/p65 expression may provide a potential treatment to manage painful inflammatory disorders.

Depressive symptoms enhance stress-induced inflammatory responses

Depression is a risk factor for morbidity and mortality, and immune dysregulation may be partially responsible for this link. Proinflammatory cytokines such as interleukin 6 (IL-6) are reliable predictors of quality of life, morbidity, and many causes of mortality. The current study evaluated relationships between depressive symptoms, as assessed by the CES-D, and stress-induced inflammation. The participants, 138 healthy adults, were evaluated at rest, and after a standardized laboratory speech and mental arithmetic stressor. Compared with individuals with fewer depressive symptoms, those with more depressive symptoms produced more IL-6 in response to the stressor, as well as significantly higher levels of IL-6 both 45 min and 2 h after the stressor. These findings add to our emerging understanding of the complex interactions among stress, depression, and immune dysregulation, and provide one potential pathway to explain relationships between depressive symptoms and disease.

Tyrosine hydroxylase expression in CD4(+) T cells is associated with joint inflammatory alleviation in collagen type II-induced arthritis

We have recently reported that CD4(+) T cells synthesize and secrete catecholamines that facilitate a shift of T helper 1 (Th1)/Th2 balance toward Th2 polarization. In this study, we used an animal model of human rheumatoid arthritis, collagen type II-induced arthritis (CIA), to explore relationship between catecholamine production in CD4(+) T cells and Th1-/Th2-mediated joint inflammation. Histopathological observation of ankle joints of CIA mice displayed an evident inflammatory change on day 35 and a major damage to bones on day 55 post-immunization. Expression of Th1-specific transcription factor, T-bet, and cytokines, IL-2 and IFN-γ, and Th2-specific transcription factor, GATA-3, and cytokines, IL-4 and IL-10, was all upregulated on days 35 and 55 post-immunization, but the elevated Th1 response tended to decrease and the enhanced Th2 response tended to increase with the CIA progression. Expression of tyrosine hydroxylase (TH), a rate-limiting enzyme for synthesis of catecholamines, dramatically increased in ankle joints of CIA mice, although this increase was reduced on day 55 relative to that on day 35 post-immunization. In synovial tissue of CIA ankle joints but not normal joints, CD4-, T-bet-, GATA-3-, and TH-immunoreactive cells were found. Importantly, co-expressed cells with CD4 and TH, T-bet and TH, and GATA-3 and TH were observed in synovial tissue of CIA ankle joints. These results suggest that an increase in catecholamine production occurs in inflamed joints of CIA. The catecholamines are, at least in part, from Th1 and Th2 cells, and they may be related to joint inflammatory alleviation in CIA progression.

Renal nerves drive interstitial fibrogenesis in obstructive nephropathy

The signals that drive fibrogenesis after an initiating insult to the kidney are incompletely understood. Here, we report that renal nerve stimulation after ureteral obstruction is the primary profibrotic signal and that renal denervation prevents both fibrogenesis and the inflammatory cascade. Local infusion of neural factors, norepinephrine, and calcitonin gene-related peptide (CGRP) in denervated kidneys mimicked the fibrotic response observed in innervated obstructed kidneys. Norepinephrine and CGRP act through the α(2)-adrenergic receptor and CGRP receptor, respectively, because blocking these receptors prevented fibrosis, the inflammatory response, and tubular cell death. In tubular epithelial cells, both norepinephrine and CGRP induced apoptosis and the release of profibrotic factors capable of stimulating the differentiation of fibroblasts to myofibroblasts. In conclusion, these data suggest that nerve-derived signaling molecules may drive renal fibrosis and that their suppression may be a therapeutic approach to fibrosis prevention.

Adrenergic modulation of immune cells: an update

Sympathoadrenergic pathways are crucial to the communication between the nervous system and the immune system. The present review addresses emerging issues in the adrenergic modulation of immune cells, including: the specific pattern of adrenoceptor expression on immune cells and their role and changes upon cell differentiation and activation; the production and utilization of noradrenaline and adrenaline by immune cells themselves; the dysregulation of adrenergic immune mechanisms in disease and their potential as novel therapeutic targets. A wide array of sympathoadrenergic therapeutics is currently used for non-immune indications, and could represent an attractive source of non-conventional immunomodulating agents.

Relationships and Inflammation across the Lifespan: Social Developmental Pathways to Disease

There are well documented links between close relationships and physical health, such that those who have supportive close relationships have lower rates of morbidity and mortality compared to those who do not. Inflammation is one mechanism that may help to explain this link. Chronically high levels of inflammation predict disease. Across the lifespan, people who have supportive close relationships have lower levels of systemic inflammation compared to people who have cold, unsupportive, conflict-ridden relationships. Not only are current relationships associated with inflammation, but past relationships are as well. In this article, we will first review the literature linking current close relationships across the lifespan to inflammation. We will then explore recent work showing troubled past relationships also have lasting consequence on people's inflammatory levels. Finally, we will explore developmental pathways that may explain these findings.

Restoring the balance of the autonomic nervous system as an innovative approach to the treatment of rheumatoid arthritis

The immunomodulatory effect of the autonomic nervous system has raised considerable interest over the last decades. Studying the influence on the immune system and the role in inflammation of the sympathetic as well as the parasympathetic nervous system not only will increase our understanding of the mechanism of disease, but also could lead to the identification of potential new therapeutic targets for chronic immune-mediated inflammatory diseases, such as rheumatoid arthritis (RA). An imbalanced autonomic nervous system, with a reduced parasympathetic and increased sympathetic tone, has been a consistent finding in RA patients. Studies in animal models of arthritis have shown that influencing the sympathetic (via α- and β-adrenergic receptors) and the parasympathetic (via the nicotinic acetylcholine receptor α7nAChR or by electrically stimulating the vagus nerve) nervous system can have a beneficial effect on inflammation markers and arthritis. The immunosuppressive effect of the parasympathetic nervous system appears less ambiguous than the immunomodulatory effect of the sympathetic nervous system, where activation can lead to increased or decreased inflammation depending on timing, doses and kind of adrenergic agent used. In this review we will discuss the current knowledge of the role of both the sympathetic (SNS) and parasympathetic nervous system (PNS) in inflammation with a special focus on the role in RA. In addition, potential antirheumatic strategies that could be developed by targeting these autonomic pathways are discussed.

Sympathetic and parasympathetic activity in cancer-related fatigue: more evidence for a physiological substrate in cancer survivors

Fatigue is a notable clinical problem in cancer survivors, and understanding its pathophysiology is important. This study evaluated relationships between fatigue and both sympathetic and parasympathetic nervous system activity in breast cancer survivors. Norepinephrine and heart rate variability (HRV) were evaluated at rest, as well as during and after a standardized laboratory speech and mental arithmetic stressor. The participants, 109 women who had completed treatment for stage 0-IIIA breast cancer within the past two years, were at least two months post surgery, radiation or chemotherapy, whichever occurred last. Women who reported more fatigue had significantly higher norepinephrine and lower HRV before and after the stressor than their less fatigued counterparts. Fatigue was not related to treatment or disease variables including treatment type, cancer stage, time since diagnosis, and time since treatment. Importantly, the relationship between HRV and cancer-related fatigue was sizeable. Based on research that has demonstrated characteristic age-related HRV decrements, our findings suggest a 20-year difference between fatigued and non-fatigued cancer survivors, raising the possibility that fatigue may signify accelerated aging. Furthermore, lower HRV and elevated norepinephrine have been associated with a number of adverse health outcomes; accordingly, fatigue may also signal the need for increased vigilance to other health threats.

Regulation of peripheral inflammation by the central nervous system

In inflammatory disorders such as rheumatoid arthritis, cytokines and danger signals are sensed by the central nervous system, which adapts behavior and physiologic responses during systemic stress. The central nervous system can also signal the periphery to modulate inflammation through efferent hormonal and neuronal pathways. The brain and spinal cord are involved in this bidirectional interaction. A variety of neuronal pathways that modulate synovial inflammation have been implicated, including the sympathetic and the parasympathetic branches of the autonomic system. Another mechanism, the dorsal root reflex, involves antidromic signaling along somatic afferent fibers that influences joint inflammation by releasing neuropeptides and other neuromediators in the periphery. Some of the neurotransmitters and neuroreceptors involved have been identified in preclinical models and represent novel targets for the treatment of rheumatic diseases.

Tumor necrosis factor and norepinephrine lower the levels of human neutrophil peptides 1-3 secretion by mixed synovial tissue cultures in osteoarthritis and rheumatoid arthritis

INTRODUCTION

Neutrophils and monocytes play an important role in overt inflammation in chronic inflammatory joint diseases such as rheumatoid arthritis (RA). The sympathetic nervous system (SNS) inhibits many neutrophil/monocyte functions and macrophage tumor necrosis factor (TNF), but because of the loss of sympathetic nerve fibers in inflamed tissue, sympathetic control is attenuated. In this study, we focused on noradrenergic and TNF regulation of human neutrophil peptides 1-3 (HNP1-3), which are proinflammatory bactericidal alpha-defensins.

METHODS

Synovial tissue and cells were obtained from patients with RA and osteoarthritis (OA). By using immunohistochemistry and immunofluorescence, HNP1-3 were tracked in the tissue. With synovial cell-culture experiments and ELISA, effects of norepinephrine, TNF, and cortisol on HNP1-3 were detected.

RESULTS

HNP1-3 were abundantly expressed in the synovial lining and adjacent sublining area but not in deeper layers of synovial tissue. The human beta-defensin-2, used as control, was hardly detectable in the tissue and in supernatants. HNP1-3 double-stained with neutrophils but not with macrophages, fibroblasts, T/B lymphocytes, and mast cells. Norepinephrine dose-dependently decreased HNP1-3 levels from RA and OA cells. TNF also inhibited HNP1-3 levels from OA but not from RA cells. Cortisol inhibited HNP1-3 levels only in OA patients. A combination of norepinephrine and cortisol did not show additive or synergistic effects.

CONCLUSIONS

This study demonstrated an inhibitory effect of norepinephrine on HNP1-3 of mixed synovial cells. In light of these findings, the loss of sympathetic nerve fibers with low resting norepinephrine levels might also augment the inflammatory process through HNP1-3.

Soluble neuropilin-2, a nerve repellent receptor, is increased in rheumatoid arthritis synovium and aggravates sympathetic fiber repulsion and arthritis

OBJECTIVE

In inflammatory lesions, sympathetic nerve fibers disappear soon after the start of inflammation. We identified sympathetic nerve repellents as possible causal agents in rheumatoid arthritis (RA). On nerve terminals, repellent factors bind to neuropilin-2 and its coreceptor. The aim of this study was to investigate the role of neuropilin-2 in the synovial tissue of patients with RA and patients with osteoarthritis (OA) and in experimental arthritis.

METHODS

The density of neuropilin-2-positive fibers and cells positive for semaphorin 3F (a sympathetic repellent) was investigated using immunofluorescence staining. Enzyme-linked immunosorbent assay was used to detect soluble neuropilin-2 in body fluids from patients with RA and patients with OA. An axon outgrowth assay and a neuropilin-2 Fc fusion construct (neuropilin-2Fc) were used to investigate semaphorin 3F-induced sympathetic nerve repulsion. In an animal model of type II collagen-induced arthritis, soluble neuropilin-2Fc was studied in vivo.

RESULTS

The synovial density of neuropilin-2-positive sympathetic nerve fibers was lower in RA than in OA, but the density of cells positive for semaphorin 3F was similar. In synovial fluid, the level of soluble neuropilin-2 was markedly higher in RA compared with OA. Mouse sympathetic ganglia served as an excellent model with which to study semaphorin 3F-induced nerve fiber repulsion. Neuropilin-2 and its coreceptor were present on sympathetic neurons, and semaphorin 3F bound to neuropilin-2Fc (binding constant 96 nmoles/liter). Semaphorin 3F dose-dependently increased sympathetic nerve fiber repulsion (at a 50% maximum response concentration of 160-210 nmoles/liter). In contrast to our expectations, soluble neuropilin-2Fc did not inhibit repulsion but increased the repellent effect of semaphorin 3F. In experimental arthritis, therapy with neuropilin-2Fc aggravated arthritis.

CONCLUSION

Soluble neuropilin-2 has no antirepellent activity but aggravates sympathetic nerve fiber repulsion and arthritis. Increased shedding of neuropilin-2 is probably an unfavorable sign in RA.

Uncoupling of sympathetic nervous system and hypothalamic-pituitary-adrenal axis in cirrhosis

BACKGROUND AND AIM

The hypothalamic-autonomic nervous system (HANS) axis and the hypothalamic-pituitary-adrenal (HPA) axis are stimulated in parallel in response to stress factors under healthy conditions. This physiological synergism of the axes aims at optimizing anti-inflammatory actions. Therefore, we investigated whether this synergism is altered in patients with liver cirrhosis.

METHODS

As a typical marker of the HANS axis neuropeptide Y (NPY is a neurotransmitter of the sympathetic nerve terminal) and of the HPA axis, cortisol together with adrenocorticotropic hormone (ACTH) and cortisol-binding globulin (CBG), were measured in samples from control subjects and patients with liver cirrhosis.

RESULTS

Plasma NPY was found to be increased in cirrhotic patients compared to control subjects (P < 0.01). This increase was observed to be independent of the severity of liver disease (Child class). Serum cortisol was decreased in cirrhotics, particularly in patients with Child A cirrhosis. Plasma NPY was positively correlated with serum cortisol in control subjects (r = 0.32, P < 0.05) reflecting the parallel activation of both axes under the normal condition. However, serum cortisol was not correlated with plasma NPY in cirrhotic patients. For the subgroup of Child A patients, even a negative correlation between NPY and cortisol was observed (r = -0.43, P < 0.05). No significant change in serum levels of ACTH and its positive correlation with serum cortisol was observed in cirrhotic patients.

CONCLUSIONS

The present study demonstrates that the two stress axes seem to act in parallel fashion in control subjects but are uncoupled in liver cirrhosis. We discuss how uncoupling of the two anti-inflammatory axes can occur and may contribute to the increased susceptibility for infections and lethal complications in cirrhotic patients.

An early sympathetic nervous system influence exacerbates collagen-induced arthritis via CD4+CD25+ cells

OBJECTIVE

Activation of the sympathetic nervous system (SNS) ameliorates collagen-induced arthritis (CIA) in the late phase of the disease but aggravates it in the presymptomatic phase. The aim of the present study was to determine whether CD4+CD25+ T cells are influenced by the SNS of mice and play a disease-modifying role in the early symptomatic phase of the disease.

METHODS

We tested the effects of the SNS on arthritis by transferring CD4+CD25+ T cells from sympathectomized mice immunized with type II collagen and from immunized, SNS-intact animals (controls). We further characterized transferred cells by studying forkhead box P3 (FoxP3) expression, cell proliferation, and cytokine secretion.

RESULTS

Using anti-dopamine-beta-hydroxylase antibodies for systemic sympathectomy, we noticed a time-dependent disease amelioration (strongest when sympathectomy was performed 7 days before immunization, with no effect 30 days after immunization). When CD4+CD25+ T cells from immunized and sympathectomized animals were transferred into mice with CIA (on day 32), disease severity was reduced compared with that in controls. However, the number of CD4+CD25+FoxP3+ cells and the FoxP3 expression level in CD4+CD25+ cells were not changed by sympathectomy. In a mixed assay of donor CD4+CD25- and CD4+CD25+ cells, proliferation was reduced when cells from sympathectomized animals were studied. In the same assay, secretion of tumor necrosis factor, interleukin-17 (IL-17), IL-10, and IL-4 (not interferon-gamma) was markedly reduced when cells were taken from sympathectomized animals. Culture of CD4+CD25+ cells with norepinephrine (10(-5)M) for 24 hours before transfer worsened the arthritis.

CONCLUSION

The SNS increases disease severity in the early phase of symptomatic CIA by stimulating several proinflammatory aspects of CD4+CD25+ T cells.

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.

The complex role of estrogens in inflammation

There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

Sex differences in monocyte expression of IL-6: role of autonomic mechanisms

Sex differences in the prevalence of inflammatory disorders exist, perhaps due to sex differences in cellular mechanisms that contribute to proinflammatory cytokine activity. This study analyzed sex differences of monocyte intracellular expression of IL-6 and its associations with reproductive hormones and autonomic mechanisms in 14 matched pairs of men and women ( n = 28). Monocyte intracellular IL-6 production was repeatedly assessed over two circadian periods. Sympathetic balance was estimated by heart rate variability and the ratio of power in the low-frequency (LF) to high-frequency (HF); vagal tone was indexed by the power of HF component. As compared to men, women showed greater monocyte expression of IL-6 across the circadian period. In addition, women showed lower sympathetic balance (LF/HF ratio), and greater levels of vagal tone (HF power). In women, but not men, sympathovagal balance was negatively associated with monocyte IL-6 expression, whereas vagal tone was positively associated with production of this cytokine. Levels of reproductive hormones were not related to monocyte IL-6 expression. The marked increase in monocyte expression of interleukin-6 in women has implications for understanding sex differences in risk of inflammatory disorders. Additionally, these data suggest that sex differences in sympathovagal balance or vagal tone may be a pathway to explain sex differences in IL-6 expression. Interventions that target autonomic mechanisms might constitute new strategies to constrain IL-6 production with impacts on inflammatory disease risk in women.

Heart rate variability is related to disease activity and smoking in rheumatoid arthritis patients

We investigated the heart rate variability (HRV) parameters in patients with rheumatoid arthritis (RA) and assessed their relationship with disease characteristics. Twenty-three female patients with RA [age 48+/-7 (mean+/-SD) years] free of cardiovascular diseases and 23 age- and gender-matched healthy controls were evaluated. After careful clinical examination, the following parameters were obtained after 24-h Holter recordings: average of all normal-to normal (NN) intervals over the entire 24-h ECG recording (meanNN, ms); the standard deviation for the time between NN complexes (SDNN, ms); the standard deviation of the average NN intervals for each 5-min period (SDANN, ms) and the square root of the mean-squared differences of successive NN intervals (rMSSD, ms). We also assessed quantitative parameters of the Poincaré plot: the standard deviation of the points perpendicular to the line-of-identity (SD1, ms); the standard deviation along the line-of-identity (SD2, ms) and their ratio (SD12). HRV parameters excluding SD2 were significantly lower in patients with RA, than in control group (p<0.05). Significant correlations of SDNN and SDANN with swollen joints count, Ritchie articular index, disease activity score (DAS) and disease duration were found. SDNN also correlated with leucocyte count and smoking. SD1 significantly correlated only with disease duration. Relationships between SDNN and smoking, swollen joints count and DAS were confirmed using multivariate analysis. Our data indicate that in patients with RA reduced HRV is independently associated with high disease activity and smoking. HRV assessment may be useful as a part of cardiovascular risk stratification in RA patients.

Familial orthostatic tachycardia

PURPOSE OF REVIEW

Postural tachycardia syndrome is an autonomic disorder primarily of younger women. The patient population is heterogeneous, making diagnosis and treatment a challenge. A mutation in the norepinephrine (noradrenaline) transporter gene prompted further genetic analysis.

RECENT FINDINGS

Eleven new mutations were found in the human norepinephrine transporter gene, although none were directly associated with postural tachycardia syndrome. The 5'-flanking -1012C --> T variant of the dopamine beta-hydroxylase gene was slightly increased and protection was associated with a reduced incidence of two mutations in the endothelial nitric oxide synthase gene, and one in endothelin-1. Mutations in other disease-related genes suggest a potential relationship with the pathogenesis of postural tachycardia syndrome. Benign joint hypermobility syndrome, for example, shares similar autonomic symptoms and is linked to a mutation in tenascin-X. Additional genetic findings are discussed as potential contributors to vascular health and neurodegeneration.

SUMMARY

Genetic testing can reveal molecular mechanisms of disease and provide an additional strategy for diagnosis and treatment of heterogeneous patient populations such as postural tachycardia syndrome. It is quite likely that the pathogenesis of this disorder will be attributed to numerous genetic mutations, both subtle and overt. Therefore, continued study of the relationships between genotype and phenotype are necessary to better understand this syndrome and others with associated dysautonomia.

Sympathetic neurotransmission modulates expression of inflammatory markers in the rat retina

Recent evidence suggests that diabetic retinopathy may involve some components of chronic inflammation. Since surgical sympathectomy produces most of the retinal changes noted in the retina of an STZ-treated rat in a non-diabetic rat, we wanted to determine whether sympathetic neurotransmission regulates gene and protein expression of inducible nitric oxide synthase (iNOS) and the prostaglandin (PGE2) receptor, as well as the levels of PGE2. Real-time PCR was conducted on retinal samples from rats that were surgically sympathectomized to investigate steady-state mRNA expression of iNOS in the sympathectomized and contralateral retina. Western blot analysis was done on protein samples from the sympathectomized and contralateral retina for iNOS and PGE2-EP2 receptor. An ELISA assay was done on retinal supernatant fractions to measure PGE2 levels. Additionally, human retinal endothelial cells were grown in either low (5 mM) or high (25 mM) glucose medium and stimulated with isoproterenol (beta-adrenergic receptor agonist), xamoterol (beta1-adrenergic receptor subtype agonist), or BRL37344 (beta3-adrenergic receptor subtype agonist) and the effects of agonist stimulation on iNOS and PGE2 levels in low and high glucose was investigated. Sympathectomy significantly increases gene and protein expression of iNOS, as well as levels of PGE2 and protein expression of PGE2-EP2 receptor subtype. Isoproterenol treatment for 6 h to human retinal endothelial cells grown in high glucose medium reduced iNOS protein expression, but had no effect on PGE2 levels or PGE2 receptor protein expression. iNOS expression was attenutated by stimulation with xamoterol, while BRL37344 had no effect, suggesting that the iNOS effects are mediated by beta1-adrenergic receptors. These results suggest that loss of sympathetic activity, as occurs in diabetes, results in an upregulation of iNOS and PGE2-EP2 receptor protein expression, as well as PGE2 levels. Isoproterenol stimulation of human retinal endothelial cells cultured in a hyperglycemic environment decreased iNOS expression with no change in PGE2 levels, suggesting that only iNOS expression is modulated by sympathetic neurotransmission in endothelial cells. Overall, these results further the idea that alterations in sympathetic neurotransmission may result in many of the changes noted in the retina of the STZ-treated rat.

[Update on rheuma-orthopedics - role and therapeutic options]

Orthopaedic treatment options for rheumatological patients have been further developed over recent years. For orthopaedic treatment, a range of different interventions are offered: orthoses and special technical aids as well as injections for joints and tendons, or surgery. Surgical interventions cover joint preservation, restitution and arthrodeses. Improvements in equipment and surgical procedures also make minimally invasive interactions possible for rheumatoid diseases. Thus, postoperative morbidity has been reduced significantly. Improvement in function, reduction of pain and prevention of recurrent local inflammation are primary. Considering these aims, arthrodeses are restricted to special indications. Joint preservation and restitution are the predominant measures used. The various procedures are discussed.