Search

The research consortium Neuroimmunology and Pain (Neuroimpa) explores the importance of the relationships between the immune system and the nervous system in musculoskeletal diseases for the generation of pain and for the course of fracture healing and arthritis.The spectrum of methods includes analyses at the single cell level, in vivo models of arthritis and fracture healing, imaging studies on brain function in animals and humans and analysis of data from patients.Proinflammatory cytokines significantly contribute to the generation of joint pain through neuronal cytokine receptors. Immune cells release opioid peptides which activate opioid receptors at peripheral nociceptors and thereby evoke hypoalgesia. The formation of new bone after fractures is significantly supported by the nervous system. The sympathetic nervous system promotes the development of immune-mediated arthritis. The studies show a significant analgesic potential of the neutralization of proinflammatory cytokines and of opioids which selectively inhibit peripheral neurons. Furthermore, they show that the modulation of neuronal mechanisms can beneficially influence the course of musculoskeletal diseases.Interventions in the interactions between the immune system and the nervous system hold a great therapeutic potential for the treatment of musculoskeletal diseases and pain.

Nerve fibers can exert trophic/anti-trophic effects on epithelial cells. Substance P (SP) is a pro-proliferative neuropeptide, whereas sympathetic noradrenaline is anti-proliferative at high concentrations.Density of noradrenergic and sensory nerve fibers and presence of nerve repellent factors specific for noradrenergic (semaphorin 3F) and sensory nerve fibers (semaphorin 3A) were investigated in colorectal adenomas.The pedunculus was innervated by noradrenergic fibers, whereas the mucosa was sparsely innervated. The control submucosa compared with control mucosa demonstrated increased density of noradrenergic fibers. Control tissue was much better innervated than the polyp. This was accompanied by strong expression of semaphorin 3F in epithelial cells. Density of sensory SP+ nerve fibers was higher in control colon mucosa compared with polyp mucosa, and SP+ cell clusters and semaphorin 3A-positive cells appeared in the intercrypt space in polyps, but not in control tissue.This study demonstrated a marked loss of noradrenergic and sensory nerve fibers in polyp mucosa, which was associated with a strong increase of semaphorin 3F and 3A. Up-regulation of the sympathetic repellent semaphorin 3F in the polyps possibly triggers sympathetic repulsion and polyp growth due to the loss of anti-proliferative noradrenaline and presence of SP from local SP+ cells.

After two decades of enormous improvements in anti-inflammatory therapy with biologics long-standing disease sequelae in chronic inflammatory diseases (CID) can be recognized, such as fatigue, anorexia/malnutrition, cachectic obesity, insulin resistance, dyslipidemia, changes of steroid hormone axes (e. g. loss of androgens), increased sympathetic nervous tone/decreased parasympathetic nervous tone, inflammation-related anemia and osteopenia. This article demonstrates for the first time in the German language a new theory to explain the pathophysiology of these disease sequelae. It includes concepts from evolutionary medicine and neuroendocrine regulation of energy allocation. The core statement is: the networks of energy regulation and energy allocation have been evolutionarily positively selected for transient inflammatory episodes (not for CIDs due to the negative selection pressure) but long-standing use of these adaptive programs for CID support systemic disease sequelae. These considerations might help to deviate focus from pure anti-inflammatory treatment to adequate diagnosis and therapy of systemic disease sequelae.

Circadian rhythms play an important role in the function of the body. Among others, the activity of the immune system is subject to daily variability which explains the different intensity of rheumatic symptoms during the day (e.g. morning stiffness). Circadian rhythms are subject to continuous adaptation via external time signals (zeitgebers), such as light-dark periods, time of food intake, as well as daily activity and resting periods. Following an acute phase shift of these external zeitgebers, e.g. via transmeridian travel (east-west or west-east), the body has to adjust all circadian systems to these new circumstances during an adjustment response, which lasts for several days. The classical symptoms of jet lag, such as tiredness during the day, mood swings and cognitive malfunction occur during this adjustment period. The impact of acute phase shifts as a result of transmeridian travel in subjects with rheumatic disorders, as well as strategies to prevent jet lag will be discussed in the following article.

Clinical observations in chronic inflammatory diseases have demonstrated the significant influence of neuroendocrine mechanisms on the immune system: (1) Amelioration of rheumatoid arthritis during pregnancy; (2) preponderance of women versus men with respect to autoimmune diseases; (3) negative effects of ovulation-inducing therapy, oral contraceptives, and hormone replacement therapy; (4) protective effect of hemiplegia; (5) influence of psychological stress on inflammation; and (6) influence of circadian rhythms on inflammatory symptoms.The effects of different hormones and neurotransmitters on the immune system are influenced by: (1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses, (2) the cell types involved during different phases of the disease, (3) the target organ with its specific microenvironment, (4) the timing of hormone or neurotransmitter increase in relation to the disease course, (5) the concentration of hormones and neurotransmitters, (6) the variability in expression of receptors depending on the microenvironment and the cell type, and (7) the intra- and extracellular peripheral metabolism of hormones and neurotransmitters leading to important biologically active metabolites with quite different anti- and proinflammatory functions.The circadian rhythm of disease-related symptoms with a peak in the early morning hours confirms that the neuroendocrine system has a strong influence on these chronic immune/inflammatory diseases. The influence is transmitted by the circadian fluctuation in the activity of hormonal and neuronal pathways linking the brain to immune cell activation.These considerations could lead to novel therapeutic strategies for rheumatic diseases in the future.

Energy regulation (EnR) is most important for homoeostatic regulation of physiological processes. Neuroendocrine pathways are involved in EnR. We can separate factors that provide energy-rich fuels to stores [parasympathetic nervous system (PSNS), insulin, insulin-like growth factor-1, oestrogens, androgens and osteocalcin] and those that provide energy-rich substrates to consumers [sympathetic nervous system (SNS), hypothalamic-pituitary-adrenal axis, thyroid hormones, glucagon and growth hormone]. In chronic inflammatory diseases (CIDs), balanced energy-rich fuel allocation to stores and consumers, normally aligned with circadian rhythms, is largely disturbed due to the vast fuel consumption of an activated immune system (up to 2000 kJ day(-1)). Proinflammatory cytokines such as tumour necrosis factor or interleukins 1beta and 6, circulating activated immune cells and sensory nerve fibres signal immune activation to the rest of the body. This signal is an appeal for energy-rich fuels as regulators are switched on to supply energy-rich fuels ('energy appeal reaction'). During evolution, adequate EnR evolved to cope with nonlife-threatening diseases, not with CIDs (huge negative selection pressure and reduced reproduction). Thus, EnR is inadequate in CIDs leading to many abnormalities, including sickness behaviour, anorexia, hypovitaminosis D, cachexia, cachectic obesity, insulin resistance, hyperinsulinaemia, dyslipidaemia, fat deposits near inflamed tissue, hypoandrogenaemia, mild hypercortisolaemia, activation of the SNS (hypertension), CID-related anaemia and osteopenia. Many of these conditions can contribute to the metabolic syndrome. These signs and symptoms become comprehensible in the context of an exaggerated call for energy-rich fuels by the immune system. We propose that the presented pathophysiological framework may lead to new therapeutical approaches and to a better understanding of CID sequence.

Molecular imaging is a rapidly emerging field in biomedical research, aiming at the visualization, characterization and quantification of molecular and cellular processes non-invasively within intact living organisms. To sense biological processes such as gene expression, angiogenesis, apoptosis or cell trafficking in vivo, imaging reporter agents that interact specifically with molecular targets and appropriate imaging systems are currently under development. In rheumatoid arthritis, these novel tools will be used to evaluate physiological and pathophysiological processes, to facilitate diagnosis and monitor therapeutic regimens, to enable reliable prognosis and to support the development of new therapies. In this review, we summarize the basic principles of molecular imaging, such as the development of molecular imaging agents, the actual capabilities of different imaging modalities and the most recent advances in molecular imaging, demonstrating the potential of this technology. With regard to their applicability in rheumatic diseases, we discuss potential molecular targets, current experimental approaches and the future prospects for molecular imaging in rheumatoid arthritis.

Recent insights into the mechanisms of genomic and non-genomic glucocorticoid actions have stimulated the search for novel glucocorticoid receptor ligands. These efforts are driven by the need to improve the benefit-risk ratio of these important drugs. Glucocorticoids are very frequently and successfully used drugs which mediate important immunosuppressive and anti-inflammatory effects, but unfortunately they have pleiotropic effects causing a number of adverse reactions which limit their clinical use, especially at higher dosages and for longer periods. For this reason, novel glucocorticoid receptor ligands are being developed, among them selective glucocorticoid receptor agonists (SEGRAs). SEGRAs are drugs that predominantly induce transrepression effects (inhibition of protein synthesis), whereas the transactivation activity (induction of protein synthesis) is significantly reduced as compared with conventional glucocorticoid drugs. This makes sense since it became evident over the last few years that many adverse effects are predominantly caused by the transactivation mechanism, whereas anti-inflammatory effects are mostly mediated by transrepression mechanisms. Other interesting examples for exciting new developments are NO-glucocorticoids and long-circulating liposomal glucocorticoids. It is, however, true of all these developments that further in vivo and in vitro investigations and clinical trials will have to define in more detail their safety-efficacy profile in order to answer the questions whether these drugs as "improved glucocorticoids" will enter clinical medicine in the near future.

Dehydroepiandrosterone is a steroid hormone used as an 'over-the-counter' drug in the USA. Treatment with dehydroepiandrosterone was effective in randomized controlled trials in patients with systemic lupus erythematosus. Dehydroepiandrosterone sulphate concentrations are decreased in patients with inflammatory bowel disease. Dehydroepiandrosterone inhibits nuclear factor-kappaB and the secretion of interleukin-6 and interleukin-12 via the peroxisome proliferator-activated receptor alpha.A phase II pilot trial was started to evaluate the effect of dehydroepiandrosterone in active inflammatory bowel disease.Twenty patients with chronic active inflammatory bowel disease [seven Crohn's disease (Crohn's disease activity index, 242 +/- 51; mean +/- s.d.); 13 ulcerative colitis (clinical activity index, 7.8 +/- 2.1)] took 200 mg dehydroepiandrosterone per day orally for 56 days.Six of the seven patients with Crohn's disease and eight of the 13 patients with ulcerative colitis responded to treatment, with a decrease in the Crohn's disease activity index of70 points and a decrease in the clinical activity index of4 points, respectively. Six Crohn's disease patients and six ulcerative colitis patients went into remission (Crohn's disease activity index150; clinical activity indexor= 4). No patient withdrew from the study because of side-effects.In a pilot study, dehydroepiandrosterone was effective and safe in patients with refractory Crohn's disease or ulcerative colitis. Adjustment of the dehydroepiandrosterone dosage may further improve the treatment success.

Cytokines (IL-1, IL-6, IL-8, IL-11, TNF, IFN-gamma, and TGF-beta) and growth factors (EGF, bFGF, aFGF, and KGF) play an important role in modulation of hormone secretion by directly influencing specific enzyme steps of steroidogenesis in various endocrine cell types. For this tabular data collection, the following enzyme steps were considered: steroidogenic acute regulatory protein (StAR), side chain cleavage enzyme (P450scc), 3 beta-hydroxysteroid dehydrogenase, 17-alpha-hydroxylase/17,20-lyase (P450c17), 17-beta-hydroxysteroid-dehydrogenase, aromatase complex, 5-alpha-reductase, P450c21, DHEAS sulfatase, and DHEA sulfotransferase. This collection summarizes the current information on how the mentioned cytokines and growth factors influence particular enzyme steps.

During the last years, examination of autonomic nervous function and of autonomic neuropathy has attracted attention not only in diabetes mellitus research but also in other areas of internal medicine. However, patients with various chronic diseases with autoimmune phenomenons have never been investigated in a comparative study with standardized examination techniques. Hence, the aim of the study was to examine the prevalence and the severity of autonomic neuropathy in patients with the following chronic diseases.We investigated 28 patients with Crohn's disease (CD: age: 32.4 +/- 2.0 y), 17 patients with ulcerative colitis (UC: 39.7 +/- 3.6 y), 39 patients with systemic lupus erythematosus (SLE: 34.9 +/- 2.0 y), 38 patients with progressive systemic sclerosis (pSS; 51.5 +/- 2.4 y) and 65 patients with insulin-dependent diabetes mellitus (IDDM: 35.5 +/- 1.6 y). Cardiovascular autonomic (cANP), pupillary autonomic (pANP), and sensorimotor (ssNP) neuropathy were assessed by standardized techniques.Prevalence rates for cANP, pANP and ssNP were found to be 0%, 19%, and 7% in CD, 6%, 25%, and 18% in UC, 5%, 29%, and 10% in SLE, 11%, 16%, and 32% in pSS, and 26%, 66%, and 29% in IDDM, respectively.The study demonstrated patients with IDDM to have the highest prevalence rates of cANP and pANP. Patients with other chronic diseases, particularly SLE, pSS and UC, had high prevalence rates of pANP. This may be due to alterations of structures of the central nervous system in these patients. cANP was rare in patients with inflammatory bowel disease and ssNP was found very often in patients with pSS, probably due to local fibrotic lesions. The various disease groups differ in the pattern and severity of autonomic and sensorimotor neuropathy, which indicates that different structures and neuropathogenic mechanisms may be involved.

Vasculitides are rare diseases characterized by inflammation of blood vessels. According to diameter of the blood vessels involved in the inflammatory process, the clinical presentation and the histological appearance, different vasculitic syndromes may be distinguished. Primary vasculitides are of unknown origin while secondary vasculitides may be caused by drugs, malignancy or infection. Panarteriitis nodosa caused by chronic Hepatitis B and mixed cryoglobulinemia secondary to chronic Hepatitis C are classical examples of vasculitides triggered by infections. However, these are rare complications of chronic viral hepatitis. Patients infected by HIV frequently suffer from vasculitis, which may be caused by opportunistic infections and by defects in immune regulation. In numerous case reports, various other infectious particles have been reported to cause different forms of vasculitis, either by direct infection of endothelial cells or by induction of an immunologic process leading to blood vessel destruction. Immunologically mediated vasculitis secondary to infection may be due to a predisposing reactivity of the patient's immune system. After successful treatment of the infection, the vasculitis usually subsides. Therefore, all patients with vasculitis should be evaluated for underlying infection.