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Gut bacteria associated with chronic pain for first time

Press Release:

Scientists have found a correlation between a disease involving chronic pain and alterations in the gut microbiome.

Fibromyalgia affects 2-4 percent of the population and has no known cure. Symptoms include fatigue, impaired sleep and cognitive difficulties, but the disease is most clearly characterized by widespread chronic pain. In a paper published today in the journal Pain, a Montreal-based research team has shown, for the first time, that there are alterations in the bacteria in the gastrointestinal tracts of people with fibromyalgia. Approximately 20 different species of bacteria were found in either greater or are lesser quantities in the microbiomes of participants suffering from the disease than in the healthy control group.

Greater presence or absence of certain species of bacteria

“We used a range of techniques, including Artificial Intelligence, to confirm that the changes we saw in the microbiomes of fibromyalgia patients were not caused by factors such as diet, medication, physical activity, age, and so on, which are known to affect the microbiome,” says Dr. Amir Minerbi, from the Alan Edwards Pain Management Unit at the McGill University Health Centre (MUHC), and first author on the paper. The team also included researchers from McGill University and Université de Montréal as well as others from the Research Institute of the MUHC.

Dr. Minerbi adds, “We found that fibromyalgia and the symptoms of fibromyalgia – pain, fatigue and cognitive difficulties – contribute more than any of the other factors to the variations we see in the microbiomes of those with the disease. We also saw that the severity of a patient’s symptoms was directly correlated with an increased presence or a more pronounced absence of certain bacteria – something which has never been reported before.”

Are bacteria simply the markers of the disease?

At this point, it’s not clear whether the changes in gut bacteria seen in patients with fibromyalgia are simply markers of the disease or whether they play a role in causing it. Because the disease involves a cluster of symptoms, and not simply pain, the next step in the research will be to investigate whether there are similar changes in the gut microbiome in other conditions involving chronic pain, such as lower back pain, headaches and neuropathic pain.

The researchers are also interested in exploring whether bacteria play a causal role in the development of pain and fibromyalgia. And whether their presence could, eventually, help in finding a cure, as well as speed up the process of diagnosis.

Confirming a diagnosis and next steps towards finding a cure

Fibromyalgia is a disease that has proved difficult to diagnose. Patients can wait as long as 4 to 5 years to get a final diagnosis. But this may be about to change.

“We sorted through large amounts of data, identifying 19 species that were either increased or decreased in individuals with fibromyalgia,” says Emmanuel Gonzalez, from the Canadian Center for Computational Genomics and the Department of Human Genetics at McGill University. “By using machine learning, our computer was able to make a diagnosis of fibromyalgia, based only on the composition of the microbiome, with an accuracy of 87 per cent. As we build on this first discovery with more research, we hope to improve upon this accuracy, potentially creating a step-change in diagnosis.”

“People with fibromyalgia suffer not only from the symptoms of their disease but also from the difficulty of family, friends and medical teams to comprehend their symptoms,” says Yoram Shir, the senior author on the paper who is the Director of the Alan Edwards Pain Management Unit at the MUHC and an Associate Investigator from the BRaiN Program of the RI-MUHC. “As pain physicians, we are frustrated by our inability to help, and this frustration is a good fuel for research. This is the first evidence, at least in humans, that the microbiome could have an effect on diffuse pain, and we really need new ways to look at chronic pain.”

How the research was done

The research was based on a cohort of 156 individuals in the Montreal area, 77 of whom suffer from fibromyalgia. Participants in the study were interviewed and gave stool, blood, saliva and urine samples, which were then compared with those of healthy control subjects, some of whom lived in the same house as the fibromyalgia patients or were their parents, offspring or siblings.

The researchers’ next steps will be to see whether they get similar results in another cohort, perhaps in a different part of the world, and to do studies in animals to discover whether changes in bacteria play a role in the development of the disease.

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To read the article, “Altered microbiome composition in individuals with fibromyalgia” by Amir Minerbi et al in Pain: https://journals.lww.com/pain/Abstract/publishahead/Altered_microbiome_composition_in_individuals_with.98647.aspx

The research was funded by the Louise and Alan Edwards Foundation and the Israeli Society for Musculoskeletal Medicine.

Contact:

Julie Robert
Communications (Research)
McGill University Health Centre
T : 514 934-1934 ext. 71381
C : 514 971-4747
julie.robert@muhc.mcgill.ca
muhc.ca I rimuhc.ca

Altered microbiome composition in individuals with fibromyalgia

Abstract:

Fibromyalgia (FM) is a prevalent syndrome, characterised by chronic widespread pain, fatigue and impaired sleep, that is challenging to diagnose and difficult to treat. The microbiomes of 77 women with FM and that of 79 control participants were compared using 16S rRNA gene amplification and whole genome sequencing.

When comparing FM patients to unrelated controls using differential abundance analysis, significant differences were revealed in several bacterial taxa. Variance in the composition of the microbiomes was explained by FM-related variables more than by any other innate or environmental variable and correlated with clinical indices of FM. In line with observed alteration in butyrate metabolising species, targeted serum metabolite analysis verified differences in the serum levels of butyrate and propionate in FM patients.

Using machine learning algorithms, the microbiome composition alone allowed for the classification of patients and controls (ROC AUC 87.8%). To the best of our knowledge, this is the first demonstration of gut microbiome alteration in non-visceral pain. This observation paves the way for further studies, elucidating the pathophysiology of FM, developing diagnostic aids and possibly allowing for new treatment modalities to be explored.

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

Source: Minerbi, Amir; Gonzalez, Emmanuel; Brereton, Nicholas J.B.; Anjarkouchian, Abraham; Dewar, Ken; Fitzcharles, Mary-Ann; Chevalier, Stéphanie; Shir, Yoram. Altered microbiome composition in individuals with fibromyalgia. PAIN: June 18, 2019 – Volume Articles in Press doi: 10.1097/j.pain.0000000000001640 https://journals.lww.com/pain/Abstract/publishahead/Altered_microbiome_composition_in_individuals_with.98647.aspx

Hyperactivation of proprioceptors induces microglia-mediated long-lasting pain in a rat model of chronic fatigue syndrome

Abstract:

BACKGROUND: Patients diagnosed with chronic fatigue syndrome (CFS) or fibromyalgia experience chronic pain. Concomitantly, the rat model of CFS exhibits microglial activation in the lumbar spinal cord and pain behavior without peripheral tissue damage and/or inflammation. The present study addressed the mechanism underlying the association between pain and chronic stress using this rat model.

METHODS: Chronic or continuous stress-loading (CS) model rats, housed in a cage with a thin level of water (1.5 cm in depth), were used. The von Frey test and pressure pain test were employed to measure pain behavior. The neuronal and microglial activations were immunohistochemically demonstrated with antibodies against ATF3 and Iba1. Electromyography was used to evaluate muscle activity.

RESULTS: The expression of ATF3, a marker of neuronal hyperactivity or injury, was first observed in the lumbar dorsal root ganglion (DRG) neurons 2 days after CS initiation. More than 50% of ATF3-positive neurons simultaneously expressed the proprioceptor markers TrkC or VGluT1, whereas the co-expression rates for TrkA, TrkB, IB4, and CGRP were lower than 20%. Retrograde labeling using fluorogold showed that ATF3-positive proprioceptive DRG neurons mainly projected to the soleus. Substantial microglial accumulation was observed in the medial part of the dorsal horn on the fifth CS day. Microglial accumulation was observed around a subset of motor neurons in the dorsal part of the ventral horn on the sixth CS day. The motor neurons surrounded by microglia were ATF3-positive and mainly projected to the soleus. Electromyographic activity in the soleus was two to three times higher in the CS group than in the control group. These results suggest that chronic proprioceptor activation induces the sequential activation of neurons along the spinal reflex arc, and the neuronal activation further activates microglia along the arc. Proprioceptor suppression by ankle joint immobilization significantly suppressed the accumulation of microglia in the spinal cord, as well as the pain behavior.

CONCLUSION: Our results indicate that proprioceptor-induced microglial activation may be a key player in the initiation and maintenance of abnormal pain in patients with CFS.

Source: Yasui M, Menjyo Y, Tokizane K, Shiozawa A, Tsuda M, Inoue K, Kiyama H. Hyperactivation of proprioceptors induces microglia-mediated long-lasting pain in a rat model of chronic fatigue syndrome. J Neuroinflammation. 2019 Mar 30;16(1):67. doi: 10.1186/s12974-019-1456-x. https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-019-1456-x (Full article)

Relationship Between Exercise-induced Oxidative Stress Changes and Parasympathetic Activity in Chronic Fatigue Syndrome: An Observational Study and in Patients and Healthy Subjects

Abstract:

PURPOSE: Oxidative stress has been proposed as a contributor to pain in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). During incremental exercise in patients with ME/CFS, oxidative stress enhances sooner and antioxidant response is delayed. We explored whether oxidative stress is associated with pain symptoms or pain changes following exercise, and the possible relationships between oxidative stress and parasympathetic vagal nerve activity in patients with ME/CFS versus healthy, inactive controls.

METHODS: The present study reports secondary outcomes from a previous work. Data from 36 participants were studied (women with ME/CFS and healthy controls). Subjects performed a submaximal exercise test with continuous cardiorespiratory monitoring. Levels of thiobarbituric acid-reactive substances (TBARSs) were used as a measure of oxidative stress, and heart rate variability was used to assess vagal activity. Before and after the exercise, subjects were asked to rate their pain using a visual analogic scale.

FINDINGS: Significant between-group differences in pain at both baseline and following exercise were found (both, P < 0.007). In healthy controls, pain was significantly improved following exercise (P = 0.002). No change in oxidative stress level after exercise was found. Significant correlation between TBARS levels and pain was found at baseline (r = 0.540; P = 0.021) and after exercise (r = 0.524; P = 0.024) in patients only. No significant correlation between TBARS and heart rate variability at baseline or following exercise was found in either group. However, a significant correlation was found between exercise-induced changes in HRV and TBARS in healthy controls (r = -0.720; P = 0.001).

IMPLICATIONS: Oxidative stress showed an association with pain symptoms in people with ME/CFS, but no exercise-induced changes in oxidative stress were found. In addition, the change in parasympathetic activity following exercise partially accounted for the change in oxidative stress in healthy controls. More research is required to further explore this link.

Source: Polli A, Van Oosterwijck J, Nijs J, Marusic U, De Wandele I5Paul L, Meeus M, Moorkens G, Lambrecht L, Ickmans K. Relationship Between Exercise-induced Oxidative Stress Changes and Parasympathetic Activity in Chronic Fatigue Syndrome: An Observational Study and in Patients and Healthy Subjects. Clin Ther. 2019 Jan 18. pii: S0149-2918(18)30611-8. doi: 10.1016/j.clinthera.2018.12.012. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30665828

Activity in Chronic Fatigue Syndrome: An Observational Study and in Patients and Healthy Subjects

Abstract:

Source: Polli A, Van Oosterwijck J, Nijs J, Marusic U, De Wandele I, Paul L, Meeus M, Moorkens G, Lambrecht L, Ickmans K. Activity in Chronic Fatigue Syndrome: An Observational Study and in Patients and Healthy Subjects. Clin Ther. 2019 Jan 18. pii: S0149-2918(18)30611-8. doi: 10.1016/j.clinthera.2018.12.012. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30665828

The link between idiopathic intracranial hypertension, fibromyalgia, and chronic fatigue syndrome: exploration of a shared pathophysiology

Abstract:

PURPOSE: Idiopathic intracranial hypertension (IICH) is a condition characterized by raised intracranial pressure (ICP), and its diagnosis is established when the opening pressure measured during a lumbar puncture is elevated >20 cm H2O in nonobese patients or >25 cm H2O in obese patients. Papilledema is caused by forced filling of the optic nerve sheath with cerebrospinal fluid (CSF). Other common but underappreciated symptoms of IICH are neck pain, back pain, and radicular pain in the arms and legs resulting from associated increased spinal pressure and forced filling of the spinal nerves with CSF. Widespread pain and also several other characteristics of IICH share notable similarities with characteristics of fibromyalgia (FM) and chronic fatigue syndrome (CFS), two overlapping chronic pain conditions. The aim of this review was to compare literature data regarding the characteristics of IICH, FM, and CFS and to link the shared data to an apparent underlying physiopathology, that is, increased ICP.

METHODS: Data in the literature regarding these three conditions were compared and linked to the hypothesis of the shared underlying physiopathology of increased cerebrospinal pressure.

RESULTS: The shared characteristics of IICH, FM, and CFS that can be caused by increased ICP include headaches, fatigue, cognitive impairment, loss of gray matter, involvement of cranial nerves, and overload of the lymphatic olfactory pathway. Increased pressure in the spinal canal and in peripheral nerve root sheaths causes widespread pain, weakness in the arms and legs, walking difficulties (ataxia), and bladder, bowel, and sphincter symptoms. Additionally, IICH, FM, and CFS are frequently associated with sympathetic overactivity symptoms and obesity. These conditions share a strong female predominance and are frequently associated with Ehlers-Danlos syndrome.

CONCLUSION: IICH, FM, and CFS share a large variety of symptoms that might all be explained by the same pathophysiology of increased cerebrospinal pressure.

Source: Hulens M, Rasschaert R, Vansant G, Stalmans I, Bruyninckx F, Dankaerts. The link between idiopathic intracranial hypertension, fibromyalgia, and chronic fatigue syndrome: exploration of a shared pathophysiology. J Pain Res. 2018 Dec 10;11:3129-3140. doi: 10.2147/JPR.S186878. eCollection 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6292399/ (Full article)

Pain is associated with reduced quality of life and functional status in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Background and aims: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is challenging to live with, often accompanied by pervasive fatigue and pain, accompanied by decreased quality of life (QoL) as well as anxiety and/or depression. Associations between higher pain, lower QoL and higher anxiety and depression have been shown in patients with various chronic pain disorders. Few studies have however examined such associations in a sample of patients with ME/CFS.

The aims of the current study were to examine the impact of pain levels and compare levels of pain, health related QoL, anxiety and depression between patients with ME/CFS and healthy controls. In addition, the study aimed and to examine these relationships within the patient group only.

Methods: This is a cross-sectional questionnaire based study comparing 87 well-diagnosed patients with ME/CFS with 94 healthy controls. The De Paul Symptom Questionnaire (DSQ), the Medical Outcomes Study Short-Form Surveys (SF-36) and the Hospital Anxiety and Depression Scale (HADS) were used to examine and compare pain, physical function, QoL, anxiety and depression in patients and healthy controls. Further the pain variables were divided into pain total, pain intensity and a pain frequency score for analyses of the above mentioned variables within the patient group only.

Results: Significantly higher levels of pain, anxiety and depression, and lower levels of QoL were found in the patient group compared with healthy controls. For the patient group alone, pain was significantly associated with lower QoL in terms of physical functioning, bodily pain, general health functioning, vitality and social functioning capacity. In this patient sample, only frequency of joint pain showed significant difference in psychological variables such as depression and anxiety – depression combined.

Conclusions: ME/CFS patients differ significantly from healthy controls in pain, health related QoL, anxiety and depression. Pain is significantly associated with reduced QoL and overall a lower level of functioning. The relation between pain and anxiety and depression appears less clear. Implications Pain is for many ME/CFS patients associated with reduced physical functioning and reduced QoL. A thorough pain assessment can therefore be essential for clinicians, and subsequent medical pain treatment combined with good pain coping skills may increase functioning level and QoL for these patients. The link between joint pain and psychological factors should also be focused in clinical practice in terms of mapping and counseling. Pain should be further examined to understand the importance it may have for functioning level as reduced function is a main criteria when diagnosing the patients.

Source: Strand EB, Mengshoel AM, Sandvik L, Helland IB, Abraham S, Nes LS. Pain is associated with reduced quality of life and functional status in patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Scand J Pain. 2018 Oct 16. pii: /j/sjpain.ahead-of-print/sjpain-2018-0095/sjpain-2018-0095.xml. doi: 10.1515/sjpain-2018-0095. [Epub ahead of print]

Exercise-induce hyperalgesia, complement system and elastase activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome – a secondary analysis of experimental comparative studies

Abstract:

Background and aims: The interaction between the immune system and pain has been thoroughly explored in the recent decades. The release of inflammatory mediators from immune cells has the capability of activating neurons and glial cells, in turn sensitizing the nervous system. Both immune system alterations and pain modulation dysfunctions have been shown in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) following exercise. However, no studies tried to explore whether these two phenomena are linked and can explain exercise-induced symptoms worsening in people with ME/CFS. We hypothesized that exercise-induced changes in descending pain modulation is associated to changes in immune system functions. We used complement system product C4a and elastase activity as indicators of immune system activity.

Methods: The study design was a secondary analysis of controlled experimental studies. Twenty-two patients with ME/CFS and 22 healthy sedentary controls were enrolled. In experiment 1, subjects performed an aerobic submaximal exercise test; in experiment 2 they underwent a self-paced exercise test. One week of rest period were set between the two exercise tests. Before and after each experiment, subjects underwent clinical assessment, pain thresholds (PPTs) measurement, and blood sampling. Immune system function was assessed measuring complement system C4a products and elastase activity.

Results: Changes in elastase activity were not associated to changes in PPTs. Associations were observed in the ME/CFS group between changes in PPTs and C4a products, following both types of exercise. After submaximal exercise, the change in C4a products was associated with the change in PPT at the thumb in patients (r=0.669, p=0.001). Similarly, after self-paced exercise the change in C4a products was associated witht the change in PPT at the calf in patients (r=0.429, p=0.047). No such correlations were found in healthy controls. Regression analysis showed that C4a changes after the submaximal exercise significantly predicted the change in PPTs (R2=0.236; p=0.02).

Conclusions: Moderate associations between exercise-induced changes in PPTs and immune system activity were found only in ME/CFS. The change in the complement system following submaximal exercise might be able to explain part of the change in patient’s pain thresholds, providing evidence for a potential link between immune system alteration and dysfunctional endogenous pain modulation. These results have to be taken with caution, as only one out of three measures of PPTs was found associated with C4a changes. We cannot reject the hypothesis that C4a might therefore be a confounding factor, and changes during exercise might be mediated by other mechanism. Implications Immune system changes following exercise might contribute to exercise-induced symptoms worsening in patients with ME/CFS. However, the role of the complement system is questionable.

Source: Polli A, Van Oosterwijck J, Meeus M, Lambrecht L, Nijs J, Ickmans K. Exercise-induce hyperalgesia, complement system and elastase activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome – a secondary analysis of experimental comparative studies. Scand J Pain. 2018 Oct 16. pii: /j/sjpain.ahead-of-print/sjpain-2018-0075/sjpain-2018-0075.xml. doi: 10.1515/sjpain-2018-0075. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/30325737

Unraveling the Molecular Determinants of Manual Therapy: An Approach to Integrative Therapeutics for the Treatment of Fibromyalgia and Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Abstract:

Application of protocols without parameter standardization and appropriate controls has led manual therapy (MT) and other physiotherapy-based approaches to controversial outcomes. Thus, there is an urgency to carefully define standard protocols that elevate physiotherapy treatments to rigorous scientific demands. One way in which this can be achieved is by studying gene expression and physiological changes that associate to particular, parameter-controlled, treatments in animal models, and translating this knowledge to properly designed, objective, quantitatively-monitored clinical trials (CTs).

Here, we propose a molecular physiotherapy approach (MPTA) requiring multidisciplinary teams, to uncover the scientific reasons behind the numerous reports that historically attribute health benefits to MT-treatments. The review focuses on the identification of MT-induced physiological and molecular responses that could be used for the treatment of fibromyalgia (FM) and chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME).

The systemic effects associated to mechanical-load responses are considered of particular relevance, as they suggest that defined, low-pain anatomic areas can be selected for MT treatment and yet yield overall benefits, an aspect that might result in it being essential to treat FM. Additionally, MT can provide muscle conditioning to sedentary patients without demanding strenuous physical effort, which is particularly detrimental for CFS/ME patients, placing MT as a real option for integrative medicine programs to improve FM and CFS/ME.

Source: Espejo JA, García-Escudero M, Oltra E. Unraveling the Molecular Determinants of Manual Therapy: An Approach to Integrative Therapeutics for the Treatment of Fibromyalgia and Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. Int J Mol Sci. 2018 Sep 9;19(9). pii: E2673. doi: 10.3390/ijms19092673. http://www.mdpi.com/1422-0067/19/9/2673 (Full article)

Negative Affectivity, Depression, and Resting Heart Rate Variability (HRV) as Possible Moderators of Endogenous Pain Modulation in Functional Somatic Syndromes

Abstract:

Background: Several studies have shown that patients with functional somatic syndromes (FSS) have, on average, deficient endogenous pain modulation (EPM), as well as elevated levels of negative affectivity (NA) and high comorbidity with depression and reduced resting heart rate variability (HRV) compared to healthy controls (HC). The goals of this study were (1) to replicate these findings and (2) to investigate the moderating role of NA, depression, and resting HRV in EPM efficiency within a patient group with fibromyalgia and/or chronic fatigue syndrome (CFS). Resting HRV was quantified as the root mean square of successive differences between inter-beat intervals (RMSSD) in rest, a vagally mediated time domain measure of HRV.

Methods: Seventy-eight patients with fibromyalgia and/or CFS and 33 HC completed a counter-irritation paradigm as a measure of EPM efficiency. Participants rated the painfulness of electrocutaneous stimuli (of individually calibrated intensity) on the ankle before (baseline phase), during (counter-irritation phase) and after (recovery phase) the application of a cold pain stimulus on the forearm. A larger reduction in pain in the counter-irritation phase compared to the baseline phase reflects a more efficient EPM.

Results: In contrast to our expectations, there was no difference between pain ratings in the baseline compared to counter-irritation phase for both patients and HC. Therefore, reliable conclusions on the moderating effect of NA, depression, and RMSSD could not be made. Surprisingly, patients reported more pain in the recovery compared to the counter-irritation and baseline phase, while HC did not. This latter effect was more pronounced in patients with comorbid depression, patients who rated the painfulness of the counter-irritation stimulus as high and patients who rated the painfulness of the electrocutaneous stimuli as low. We did not manage to successfully replicate the counter-irritation effect in HC or FSS patients. Therefore, no valid conclusions on the association between RMSSD, depression, NA and EPM efficiency can be drawn from this study. Possible reasons for the lack of the counter-irritation effect are discussed.

Source: Van Den Houte M, Van Oudenhove L, Van Diest I, Bogaerts K, Persoons P, De Bie J, Van den Bergh O. Negative Affectivity, Depression, and Resting Heart Rate Variability (HRV) as Possible Moderators of Endogenous Pain Modulation in Functional Somatic Syndromes. Front Psychol. 2018 Mar 6;9:275. doi: 10.3389/fpsyg.2018.00275. eCollection 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5845717/ (Full article)