The immune-inflammatory pathophysiology of fibromyalgia: increased serum soluble gp130, the common signal transducer protein of various neurotrophic cytokines

A new view on hypocortisolism

Low cortisol levels have been observed in patients with different stress-related disorders such as chronic fatigue syndrome, fibromyalgia, and post-traumatic stress disorder. Data suggest that these disorders are characterized by a symptom triad of enhanced stress sensitivity, pain, and fatigue. This overview will present data on the development, mechanisms and consequences of hypocortisolism on different bodily systems. We propose that the phenomenon of hypocortisolism may occur after a prolonged period of hyperactivity of the hypothalamic-pituitary-adrenal axis due to chronic stress as illustrated in an animal model. Further evidence suggests that despite symptoms such as pain, fatigue and high stress sensitivity, hypocortisolism may also have beneficial effects on the organism. This assumption will be underlined by some studies suggesting protective effects of hypocortisolism for the individual.

Evidence for abnormal pain processing in fibromyalgia syndrome

OBJECTIVE

To review the pathophysiology of fibromyalgia syndrome.

DESIGN

Review of the literature available on Medline (1965-2001).

RESULTS

Fibromyalgia syndrome is a chronic pain syndrome that predominantly afflicts women. It is characterized by widespread pain, insomnia, fatigue, and the presence of multiple tender points. Despite intensifying research, the etiology of fibromyalgia has remained unclear. Importantly, neither infections, trauma, nor psychiatric abnormalities consistently precede the onset of pain in patients with this syndrome. There is, however, mounting evidence for central pain processing abnormalities in almost all fibromyalgia patients. These anomalies include hyperalgesia, allodynia, abnormal temporal summation of second pain, neuroendocrine abnormalities, and abnormal activation of pain-related brain regions.

CONCLUSIONS

Multiple abnormal findings in fibromyalgia patients strongly indicate a neuropathic pain syndrome, reminiscent of complex regional pain syndrome or postherpetic neuralgia. In addition, fibromyalgia syndrome seems to share similar characteristics with these neuropathic pain syndromes, including ineffective response to many analgesics.

A Pilot trial evaluating meta050, a proprietary combination of reduced iso-alpha acids, rosemary extract and oleanolic acid in patients with arthritis and fibromyalgia

The aim of this open-label, 8-week observational trial was to investigate the efficacy of Meta050 (a proprietary, standardized combination of reduced iso-alpha-acids from hops, rosemary extract and oleanolic acid) on pain in patients with rheumatic disease. Osteoarthritis, rheumatoid arthritis and fibromyalgia patients were given 440 mg Meta050 three times a day for 4 weeks, which was changed to 880 mg twice a day for the subsequent 4 weeks in the majority of patients. Pain and condition-specific symptoms were assessed using a standard visual analog scale (VAS), an abridged arthritis impact measurement scale (AIMS2) and the fibromyalgia impact questionnaire. Fifty-four subjects with rheumatic disease completed the trial. Following treatment, a statistically significant decrease in pain of 50% and 40% was observed in arthritis subjects using the VAS (p < 0.0001; Wilcoxon-ranked sums) and AIMS2 (p < 0.0001), respectively. Fibromyalgia subject scores did not significantly improve. A decreasing trend of C-reactive protein, a marker for inflammation, was also observed in those subjects who presented with elevated C-reactive protein. No serious side effects were observed. These observations suggest that Meta050 at a dosage of 440 mg three times a day has a beneficial effect on pain in arthritis subjects.

α1-Antitrypsin and fibromyalgia: new data in favour of the inflammatory hypothesis of fibromyalgia

alpha1-Antitrypsin (AAT) circulates in high serum concentrations, and impregnates most body tissues. AAT has a broad anti-inflammatory spectrum, and modulates most inflammatory reactions occurring in human body. Recently, a possible relationship between AAT deficiency (AAT-D) and fibromyalgia (FM) has been raised, with the finding that intravenous infusions of purified human AAT efficiently controlled FM symptoms in two patients with severe hereditary AAT-D. On the other hand, functional magnetic resonance imaging has detected a significant greater activity in pain sensitive areas of the brain in patients with FM, in response to cutaneous stimuli, providing further evidence for a physiological explanation for FM pain. In recent studies abnormal profiles of inflammation markers in serum and biopsies have been found in FM patients. Since most of these inflammation mediators can be inhibited by AAT, these observations would suggest that at least a subset of the FM syndrome could be related to an inflammatory process, possibly due to an imbalance between inflammatory and anti-inflammatory substances, in the soft body tissues. Future directions of research would be: (1) to develop epidemiological studies to determine the gene frequency of AAT deficiency alleles in FM patients; (2) implementation of a double-blind placebo-controlled clinical trial to determine the specific role of AAT augmentation therapy in AAT-D patients with FM; (3) identification of specific laboratory markers for diagnostic and clinical evaluation purposes in FM; (4) application of the newest medical imaging techniques for diagnosis; and (5) identification of genetic, familial, and environmental risk factors suspected to participate in the FM syndrome development.

Fibromyalgia, hepatitis C infection, and the cytokine connection

Fibromyalgia and chronic hepatitis C infection share many clinical features including prominent somatic complaints such as musculoskeletal pain and fatigue. There is a growing body of evidence supporting a link between cytokines and somatic complaints. This review discusses alterations of cytokines in fibromyalgia, including increased serum levels of interleukin (IL)-2, IL-2 receptor, IL-8, IL-1 receptor antagonist; increased IL-1 and IL-6 produced by stimulated peripheral blood mononuclear cell in patients with FM for longer than 2 years; increased gp130, which is a neutrophil cytokine transducing protein; increased soluble IL-6 receptor and soluble IL-1 receptor antagonist only in patients with fibromyalgia who are depressed; and IL-1 beta, IL-6, and TNF-a by reverse transcriptase-polymerase chain reaction in skin biopsies of some patients with fibromyalgia. In addition, this review describes the mechanism by which alterations in cytokines in fibromyalgia and chronic hepatitis C infection can produce hyperalgesia and other neurally mediated symptoms through the presence of cytokine receptors on glial cells and opiate receptors on lymphocytes and the influence of cytokines on the hypothalamus-pituitary-adrenal axis such as IL-1, IL-6, and TNF-a activating and IL-2 and IFN-a down-regulating the HPA axis, respectively. The association between chronic hepatitis C infection and fibromyalgia is discussed, including a description of key cytokine changes in chronic hepatitis C infection. Future studies are encouraged to further characterize these immunologic alterations with potential pathophysiologic and therapeutic implications.

Intramuscular injection of tumor necrosis factor-alpha induces muscle hyperalgesia in rats

The role of proinflammatory cytokines in neuropathic and inflammatory pain is well established. Recent studies suggest that cytokines such as tumor necrosis factor-alpha (TNF) may also be involved in the development of muscle pain. To investigate the pathophysiology of intramuscular TNF, exogenous TNF (0.1-10 microg), formalin (9%) or vehicle was injected into the gastrocnemius or biceps brachii muscles of rats. To quantify muscle hyperalgesia, changes in forelimb grip force or withdrawal thresholds to increasing pressure applied to the gastrocnemius muscle were measured. TNF evoked a time- and dose-dependent muscle hyperalgesia within several hours after injection that was totally reversed by systemic treatment with the non-opioid analgesic metamizol. Paw withdrawal thresholds or latencies to mechanical and thermal stimuli, respectively, were unchanged after intramuscular injection of TNF or formalin. In contrast to formalin, which induced significant muscle tissue damage, macrophage infiltration, swelling and partial motor impairment demonstrated in rotarod tests, TNF induced neither histopathological tissue damage nor motor dysfunction. To investigate the effect of TNF and formalin on other potentially algesic mediators, muscles were analyzed for calcitonin-gene related peptide (CGRP), prostaglandin E2 (PGE2) and nerve growth factor (NGF) 1 day after injection. TNF and formalin evoked intramuscular upregulation of CGRP and NGF, whereas PGE2 was increased exclusively after TNF injection. These findings allow us to speculate that endogenous TNF may play a role in the development of muscle hyperalgesia. Targeting proinflammatory cytokines might be beneficial for the treatment of musculoskeletal pain syndromes.

Clinical evaluation of patients with temporomandibular joint implants

PURPOSE

An undetermined number of patients with temporomandibular joint (TMJ) symptoms have been treated with intra-articular disc implants composed of Teflon ethylene/propylene or Teflon polytetrafluoroethylene and aluminum oxide (Proplast-Teflon; Vitek, Houston, TX). These implants have shown the potential to fragment in situ resulting in nonbiodegradable particles that stimulate a giant cell reaction and lead to degeneration of local structures, pain, and limitation of mandibular opening. We examined the possible relationship between TMJ implants and persistent pain, responses to sensory stimuli, quality of life, and systemic immune dysfunction.

PATIENTS AND METHODS

This case series (32 patients) were referred from university-based orofacial pain centers and private practices from across the United States. Laboratory and clinical assessments evaluated orofacial pain symptoms, neurologic function, clinical signs and symptoms of rheumatologic disease, physical function, systemic measures of immune function, and behavioral measures.

RESULTS

We found that TMJ implant patients appeared to have altered sensitivity to sensory stimuli, a higher number of tender points with a diagnosis of fibromyalgia, increased self-report of chemical sensitivity, higher psychologic distress and significantly lower functional ability. Systemic illness or autoimmune disease was not evident in this series of TMJ implant patients.

CONCLUSIONS

Significant problems were noted on clinical assessment of TMJ implant patients. This is a US government work. There are no restrictions on its use.

Peripheral blood mononuclear cell beta-endorphin concentration is decreased in chronic fatigue syndrome and fibromyalgia but not in depression: preliminary report

OBJECTIVE

The aim of this study was to examine the possible role of the immune system in the pathophysiology of chronic fatigue syndrome and fibromyalgia syndrome and in the differential diagnosis of depression by investigating changes in peripheral blood mononuclear cell levels of beta-endorphin, an endogenous opioid known to be involved in regulation of the immune system function.

DESIGN

Beta-endorphin concentrations were measured by radioimmunoassay in peripheral blood mononuclear cells from healthy controls (n = 8) and patients with chronic fatigue syndrome (n = 17), fibromyalgia syndrome (n = 5), or depression (n = 10).

RESULTS

Beta-endorphin concentrations were significantly lower in patients with chronic fatigue syndrome or fibromyalgia syndrome than in normal subjects and depressed patients (p <0.001 and p <0.01, respectively). They were significantly higher in depressed patients than in controls (p <0.01).

CONCLUSIONS

Evaluation of peripheral blood mononuclear cell beta-endorphin concentrations could represent a diagnostic tool for chronic fatigue syndrome and fibromyalgia and help with differential diagnosis of these syndromes versus depression. The results obtained are also consistent with the hypothesis that the immune system is activated in both chronic fatigue syndrome and fibromyalgia syndrome.

Evaluation and management of endocrine dysfunction in fibromyalgia

Fibromyalgia-like symptoms such as muscle pain and tenderness, exhaustion, reduced exercise capacity, and cold intolerance, resemble symptoms associated with endocrine dysfunction like hypothyroidism, and adrenal or growth hormone insufficiency. To investigate the potential of management of endocrine abnormalities for relieve of symptoms of patients with fibromyalgia, we reviewed experimental and clinical studies of endocrine functioning and endocrine treatment. Serum GH, androgen, and 24-hour urinary cortisol levels of patients with fibromyalgia tend to be in the lower part of the normal range, while serum levels of thyroid hormone, female sex hormones, prolactin, and melatonin are normal. With exception of GH, these conclusions are based on studies in small samples. With respect to dynamic responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis, the dexamethasone suppression test and stimulation with ACTH show normal results, while patients show marked ACTH hypersecretion in response to severe acute stressors, perhaps indicative of chronic CRH hyposecretion. This finding and slightly altered responsiveness of growth hormone, thyroid hormone, and prolactin in pharmacologic stimulation tests suggest a central rather than peripheral origin of endocrine deviations. Because hormone level deviations were not severe, occurred in subgroups of patients only, and few controlled clinical trials were performed, there is--unless future research shows otherwise--little support for hormone supplementation as a general therapy in the common patient with fibromyalgia. In patients with clinically overt hormone deficiency, hormonal supplementation is an option. In patients with hormone levels that are in the lower part of the normal range, interventions aimed at pain, fatigue, sleep or mood disturbance, and physical deconditioning may indirectly improve endocrine functioning.

Fibromyalgia Syndrome, Idiopathic Widespread Persistent Pain or Syndrome of Myalgic Encephalomyelopathy (SME): What Is Its Nature?

CONTEXT

Fibromyalgia is a disorder that is appearing more and more in the clinical practice but is poorly understood.

OBJECTIVE

This paper attempts to look at all available and reliable data on these conditions and will outline current, scientifically sound understanding of these disorders, treatment modalities and future directions for research. It also attempts to analyze the social and cultural implications.

DATA SOURCES/STUDY SELECTION

Various terms used to describe these syndromes are fibromyalgia (FMS), and myalgic encephalomyelitis (ME). PubMed search was performed. Pertinent articles published in past 25 years and The National Academy of Sciences colloquium on Neurobiology of Pain was also reviewed. In addition, news-articles in the lay press as well as the Internet were monitored for material posted by sufferers of these disorders.

DATA EXTRACTION

Studies were reviewed for clinical presentations, history of these disorders, comorbid conditions, etiology, biochemical and microbiologic abnormalities, abnormalities found on neuroimaging and functional neurophysiologic techniques. In addition patient postings on the Internet and articles appearing in lay press were reviewed and social implications are discussed.

DATA SYNTHESIS

Upon analysis of these materials the review was organized based on the quality of data and it's contextual scientific, cultural and political meaning for this disorder. This review appears to be pointing towards an entirely new paradigm in pain disorders; therefore, a hypothesis and future direction of research is repeatedly suggested.

CONCLUSION

This study proposes an entirely new paradigm in these disorders based on scientific and cultural data.

Vulnerability to stress among women in chronic pain from fibromyalgia and osteoarthritis

In two investigations, we studied vulnerability to the negative effects of stress among women in chronic pain from 2 types of musculoskeletal illnesses, fibromyalgia syndrome (FMS) and osteoarthritis (OA). In Study 1, there were 101 female participants 50 to 78 years old: 50 had FMS, 29 had OA knee pain and were scheduled for knee surgery, and 22 had OA but were not planning surgery. Cross-sectional analyses showed that the three groups were comparable on demographic variables, personality attributes, negative affect, active coping, and perceived social support. As expected, FMS and OA surgery women reported similar levels of bodily pain, and both groups scored higher than OA nonsurgery women. However, women with FMS reported poorer emotional and physical health, lower positive affect, a poorer quality social milieu, and more frequent use of avoidant coping with pain than did both groups of women with OA. Moreover, the perception and use of social support were closely tied to perceived social stress only among the FMS group. In Study 2, we experimentally manipulated negative mood and stress in 41 women 37 to 74 years old: 20 women had FMS, and 21 women had OA. Participantsfrom each group were randomly assigned to either a negative mood induction or a neutral mood (control) condition, and then all participants discussed a stressful interpersonal eventfor 30 min. Stress-related increases in pain were exacerbated by negative mood induction among women with FMS but not women with OA, and pain during stress was associated with decreases in positive affect in women with FMS but not women with OA. These findings suggest that among women with chronic pain, those with FMS may be particularly vulnerable to the negative effects of social stress. They have fewer positive affective resources, use less effective pain-coping strategies, and have more constrained social networks than their counterparts with OA, particularly those who experience similar levels ofpain. They also seem to experience more prolonged stress-related increases in pain under certain circumstances, all of which may contribute to a lowering of positive affect and increased stress reactivity over time.

Neuroendocrine and immune aspects of fibromyalgia

Fibromyalgia is a form of non-articular rheumatism characterised by long term (>3 months) and widespread musculoskeletal aching, stiffness and pressure hyperalgesia at characteristic soft tissue sites, called soft tissue tender points. The biophysiology of fibromyalgia, however, has remained elusive and the treatment remains mainly empirical. This article reviews the neuroendocrine-immune pathophysiology of fibromyalgia. There is no major evidence that fibromyalgia is accompanied by activation of the inflammatory response system, by immune activation or by an inflammatory process. There is some evidence that fibromyalgia is accompanied by some signs of immunosuppression, suggesting that immunomodifying drugs could have potential in the treatment of fibromyalgia. Recent trials with cytokines, such as interferon-alpha, have been undertaken in patients with fibromyalgia. Immunotherapy with these agents, however, may induce symptoms reminiscent of fibromyalgia and depression in a considerable number of patients. Lowered serum activity of prolyl endopeptidase (PEP), a cytosolic endopeptidase that cleaves peptide bonds on the carboxyl side of proline in proteins of relatively small molecular mass, may play a role in the biophysiology of fibromyalgia through diminished inactivation of algesic and depression-related peptides, e.g. substance P. Trials with PEP agonists could be worthwhile in fibromyalgia. The muscle energy depletion hypothesis of fibromyalgia is supported by findings that this condition is accompanied by lowered plasma levels of branched chain amino acids (BCAAs), i.e. valine, leucine and isoleucine. Since there is evidence that BCAA supplementation decreases muscle catabolism and has ergogenic values, a supplemental trial with BCAAs in fibromyalgia appears to be justified.

Cytokines play an aetiopathogenetic role in fibromyalgia: a hypothesis and pilot study

OBJECTIVE

To measure soluble factors having a possible role in fibromyalgia (FM) and compare the profiles of patients with recent onset of the syndrome with patients with chronic FM.

METHODS

The production of cytokines, cytokine-related molecules, and a CXC chemokine, interleukin (IL)-8, was examined. Fifty-six patients with FM (23 with <2 yr and 33 with >2 yr of symptoms) were compared with age- and sex-matched healthy controls. Cytokines and cytokine-related molecules were measured in sera and in supernatants of peripheral blood mononuclear cells (PBMC) that were incubated with and without lectins and phorbol myristate acetate (PMA).

RESULTS

No differences between FMS and controls were found by measuring IL-1beta, IL-2, IL-10, serum IL-2 receptor (sIL-2R), interferon gamma (IFN-gamma), and tumour necrosis factor alpha (TNF-alpha). Levels of IL-1R antibody (IL-1Ra) and IL-8 were significantly higher in sera, and IL-1Ra and IL-6 were significantly higher in stimulated and unstimulated FM PBMC compared with controls. Serum IL-6 levels were comparable to those in controls, but were elevated in supernatants of in vitro-activated PBMC derived from patients with >2 yr of symptoms. In the presence of PMA, there were additional increases in IL-1Ra, IL-8 and IL-6 over control values.

CONCLUSIONS

In patients with FM we found increases over time in serum levels and/or PBMC-stimulated activity of soluble factors whose release is stimulated by substance P. Because IL-8 promotes sympathetic pain and IL-6 induces hyperalgesia, fatigue and depression, it is hypothesized that they may play a role in modulating FM symptoms.

Mediators of inflammation and their interaction with sleep: relevance for chronic fatigue syndrome and related conditions

In humans, activation of the primary host defense system leads to increased or decreased NREM sleep quality, depending on the degree of early immune activation. Modest elevations of certain inflammatory cytokines are found during experimental sleep loss in humans and, in addition, relatively small elevations of cytokines are seen following commencement of pharmacological treatments with clozapine, a CNS active antipsychotic agent, known to have immunomodulatory properties. Cytokines such as TNF-alpha, its soluble receptors, and IL-6, present in the periphery and the CNS, comprise a link between peripheral immune stimulation and CNS-mediated behaviors and experiences such as sleep, sleepiness, and fatigue. The debilitating fatigue experienced in chronic fatigue syndrome and related diseases may also be related to altered cytokine profiles.