Category: Pathophysiology

Chronic fatigue syndrome reflects loss of adaptability

In this issue, Van Oosterwijck et al. [1] report that physical exercise lowered pain thresholds and was associated with exacerbation of symptoms in patients with myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) whereas, on the other hand, postexercise activity levels did not significantly decrease. Based on these and similar findings in patients with CFS, we present a conceptual framework that might provide a better understanding of the key features and pathophysiological mechanisms of CFS, and thus improve its diagnosis and treatment.

CFS as a failure of allostasis?

Van Oosterwijck et al. [1] correctly note the frequent cooccurrence of a chronic ‘fatigue–pain’ symptom cluster, usually diagnosed as CFS and/or fibromyalgia. Recently, it has been proposed that this cluster should be classified under the unifying label of ‘central sensitivity syndromes’– a broad range of functional somatic disorders mainly characterized by common sensory abnormalities (i.e. widespread pain, hyperalgesia, allodynia and hypersensitivity to noise, bright light and certain chemical substances) [2].

However, ‘stress intolerance and pain hypersensitivity syndromes’ may be a more appropriate umbrella term for these syndromes because it reflects these patients’ inability to adequately adapt to all kinds of physical and mental stressors, including pathological pain processing [3]. Within the innovative neurobiological stress paradigm of ‘allostasis’– the need for stability through continuous change [4] – this general loss of adaptability may be understood as a failure of allostasis.

Although the mechanisms underlying this failure are still unclear, they may include complex and interrelated disturbances of different components of the stress system, (i.e. the hypothalamic–pituitary–adrenal (HPA) axis), the sympathetic nervous system and various neurotransmitters that modulate perceptual–cognitive and affective brain circuits, all of which operate in intimate connection with the immune system and central pain mechanisms [5].

We and others have hypothesized that the pathophysiology of CFS might include a ‘switch’ from HPA axis hyperfunction to hypofunction following a period of chronic physical and/or psychosocial stress in vulnerable persons resulting in inadequate cortisol reactivity which may in turn, via low glucocorticoid signalling, increase inflammatory activity [5]. This assumption is consistent with the relatively low basal cortisol levels and blunted diurnal cortisol rhythm frequently observed in CFS patients [5], but recent data suggest that a decrease in glucocorticoid receptor sensitivity might play a role as well [6].

Abnormal activation of innate immunity involves the release of pro-inflammatory cytokines that influence the brain and give rise to ‘sickness behaviour’. This evolutionary, physiological and behavioural reaction normally occurs during infection or severe injury and its purpose is to optimally fight bodily threats by reorganizing priorities, saving energy and promoting healing and recovery. Characteristic symptoms are profound lethargy, feelings of malaise, concentration difficulties, headache, mild fever, sensory hypersensitivity and generalized pain. In CFS patients, however, this ‘flu-like’ symptom complex may be typically provoked by any kind of stressor (e.g. physical effort, mental pressure, strong emotions) and lead to a motivational shift by urging the patient to withdraw from activities [7].

Yet, the situation may be more complex. Not only is there evidence for basal hyperfunction of the sympathetic nervous system in CFS [8] and fibromyalgia [9], but dysfunctional descending pain-inhibiting pathways [10] and various psychological mechanisms may also contribute to abnormal pain perception [11].

The data presented by Van Oosterwijck et al. [1] fit within the stress adaptability hypothesis, which includes immune-related central pain sensitization, and thus make a strong case for refining current diagnostic criteria of CFS [12] to incorporate – as a mandatory criterion –patients’ maladaptive postexertional response. Novel clinical diagnostic criteria have meanwhile been developed [13] but it remains to be seen whether these criteria will empirically prove to be appropriate in identifying the key features of the illness.

You can read the rest of this comment here: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2010.02240.x/full

Comment on: Pain inhibition and postexertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome: an experimental study. [J Intern Med. 2010]

 

Source: Van Houdenhove B, Luyten P. Chronic fatigue syndrome reflects loss of adaptability. J Intern Med. 2010 Sep;268(3):249-51. doi: 10.1111/j.1365-2796.2010.02240.x. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2010.02240.x/full (Full article)

 

An intriguing and hitherto unexplained co-occurrence: Depression and chronic fatigue syndrome are manifestations of shared inflammatory, oxidative and nitrosative (IO&NS) pathways

Abstract:

There is a significant ‘comorbidity’ between depression and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Depressive symptoms frequently occur during the course of ME/CFS. Fatigue and somatic symptoms (F&S), like pain, muscle tension, and a flu-like malaise, are key components of depression. At the same time, depression and ME/CFS show major clinical differences, which allow to discriminate them with a 100% accuracy.

This paper aims to review the shared pathways that underpin both disorders and the pathways that discriminate them. Numerous studies have shown that depression and ME/CFS are characterized by shared aberrations in inflammatory, oxidative and nitrosative (IO&NS) pathways, like systemic inflammation and its long-term sequels, including O&NS-induced damage to fatty acids, proteins and DNA; dysfunctional mitochondria; lowered antioxidant levels, like zinc and coenzyme Q10; autoimmune responses to neoepitopes formed by O&NS; lowered omega-3 polyunsaturated fatty acid levels; and increased translocation of gram-negative bacteria. Some IO&NS-related pathways, like the induction of indoleamine 2-3-dioxygenase, neurodegeneration and decreased neurogenesis, are more specific to depression, whereas other pathways, like the 2′-5′ oligoadenylate synthetase/RNase L pathway, are specific to ME/CFS.

Most current animal models of depression, e.g. those induced by cytokines, are not reminiscent of human depression but reflect a mixture of depressive and F&S symptoms. The latter symptoms, sometimes called sickness behavior, differ from depression and ME/CFS because the former is a (sub)acute response to infection-induced pro-inflammatory cytokines that aims to enhance recovery, whereas the latter are characterized by long-term sequels in multiple IO&NS pathways.

Depression and ME/CFS are not ‘comorbid’ disorders, but should be regarded as ‘co-associated disorders’ that are clinical manifestations of shared pathways.

Copyright © 2010 Elsevier Inc. All rights reserved.

 

Source: Maes M. An intriguing and hitherto unexplained co-occurrence: Depression and chronic fatigue syndrome are manifestations of shared inflammatory, oxidative and nitrosative (IO&NS) pathways. Prog Neuropsychopharmacol Biol Psychiatry. 2011 Apr 29;35(3):784-94. doi: 10.1016/j.pnpbp.2010.06.023. Epub 2010 Jul 4. https://www.ncbi.nlm.nih.gov/pubmed/20609377

 

A panel of biomarkers accurately identifies CFS/ME patients and contributes to the understanding of the pathophysiology of the disorder

Abstract: 

Background: CFS/ME is a debilitating illness for which no specific biomarkers have been identified, although several immune abnormalities including neuroinflammation have been described. The goal of this study was to assemble a panel of immune and inflammatory markers, with the ability to accurately identify CFS/ME cases.

Objectives: From observations made in clinical practice, four markers were selected (immune and inflammatory). These markers were initially investigated to establish differences between CFS/ME cases and controls. We then evaluated their potential usefulness as a diagnostic biomarker by establishing their specificity and sensitivity.

Methods: Venous blood was collected from 70 male and 70 female CFS/ME patients (mean age 43 and 44 years, respectively – Fukuda case definition was used) as well as 70 male and 70 female healthy controls (mean age 43.5 and 44.5 years, respectively).

Serum Interleukin 8 (IL-8), soluble CD14 (sCD14, a surrogate marker for bacterial LPS), and prostaglandin E2 (PGE2) were measured for all subjects as were absolute CD3- / CD57+ lymphocytes counts (CD57+ lymph), according to accepted clinical laboratory techniques.

We then established median values for all analysed parameters; independent sample t-test, Mann-Whitney test and ROC curve analysis were used to investigate difference linked to gender and age.

Results: ROC Statistics (area under the ROC curve) revealed a significant difference between CFS/ME cases and controls (p <0.001) for the four parameters separately, both in the male and female cohorts. Sensitivity was 74.3 – 80 % (females) and 52.1 – 85.9 % (males). Specificity was 57.1 – 98.1 (females) and 65.7 – 88.6 (males).

Logistic regression analysis for the combination of parameters in our panel (IL-8, sCD14, PGE2 and CD57+ lymph) correctly predicted in 89.36 % of male CFS/ME cases and in 97.14 % of female CFS/ME cases.

Conclusions: This panel differentiates CFS/ME cases from controls with high sensitivity and specificity and therefore represents a potential tool in selecting CFS/ME subjects for clinical studies. Each of these four biological markers relate strongly to the disorder.

PGE2 activates dendritic cells and suppresses their ability to attract T cells. It also suppresses the function of macrophages and neutrophils as well as Th1, CTL-, NK-cell mediated type 1 immunity (e.g. CD3- / CD57+ lymphocytes). PGE2 additionally promotes Th2, Th17 and Tregs and also modulates chemokine production (e.g. IL-8).

When taken together, these data suggest that lipopolysaccharide (LPS), likely from gut bacteria, plays an important role in the pathophysiology of CFS/ME.

This screening panel represents an initial step toward identifying biomarkers to broadly diagnose subjects with CFS/ME.

Subsequent markers will be required to subcategorize CFS/ME subjects in order to tailor therapeutic solutions.

 

Source: Kenny L. De Meirleir1,2, Tatjana Mijatovic3, Eugene Bosmans3, Nossa Van den Vonder2, Vincent Lombardi1. A panel of biomarkers accurately identifies CFS/ME patients and contributes to the understanding of the pathophysiology of the disorder. Abstract from IACFS/ME Conference 2016 Program.

1. Nevada Center for Biomedical Research at University
of Nevada, Reno, USA
2. Himmunitas vzw, Brussels, Belgium
3. RED Laboratories NV, Zellik, Belgium

 

Are symptoms of ‘hypoglycemia’ in Chronic Fatigue Syndrome (CFS) associated with hypoglycemia or orthostatic intolerance in young people?

Background: Symptoms of nausea, feeling faint, malaise and mild anxiety are common in young people with CFS and popularly attributed to ‘hypoglycemia’ resulting in various dietary interventions with little reported improvement.

Objectives: To determine whether the symptoms are associated with measured hypoglycaemia using continuous tissue glucose monitoring or whether these symptoms are associated with documented orthostatic intolerance.

Methods: Nine young people with CFS (mean age 20 years) and mean duration of 4.5 years with persistently troublesome symptoms were compared with 10 healthy adult controls without diabetes. Each subject agreed to 3 days Continuous Glucose Monitoring System (Medtronic CGMS). This is routinely used in adolescent diabetics to document food intake, tissue glucose levels and activity levels to monitor control.

Subsequently 8 of these had formal cardiac tilt table testing where heart rate and blood pressure are measured supine and during 70 degree head-up tilt for up to 10 minutes to assess the presence orthostatic intolerance (either postural orthostatic tachycardia (POTS) or neurocardiogenic hypotensive syndrome). If positive, appropriate medical management of increasing salt and fluids, gentle improvement of muscle tone and blood pressure support medications, was implemented.

Results: The tissue glucose was calibrated with the blood glucose and all fell within acceptable normal range. There was statistical (but not clinical) significance in average tissue glucose in CFS subjects. 6% of time in controls and 16.8% in CFS was spent in the range <4mmol/L glucose (95% CI -23% to +2%, p=0.1) suggesting weak evidence for a difference given the variability and small sample size. The reported presence of symptoms throughout the day was not associated with significant reduction in tissue glucose levels.

Six had confirmed evidence for POTS, one for neurocardiogenic syndrome and one for a combination of both. All 8 reported improvement in all symptoms especially nausea, dizziness and malaise with active treatment of their orthostatic intolerance.

Conclusion: This study could not confirm a link between putative symptoms of ‘hypoglycemia’ and documented hypoglycemia. This suggests that symptoms frequently attributed to ‘hypoglycemia’ may be due to orthostatic intolerance and further investigation and management of this condition provides more reported relief for these troublesome symptoms.

Dr Kathy Rowe, Senior Consultant Paediatrician, Department of General Medicine, Royal Children’s Hospital, Melbourne, Victoria, Australia 3052
kathy.rowe@rch.org.au  No conflicts of interest to declare. RCH internally funded.

 

Source: Katherine Rowe, Rebecca Gebert, Susan Donath, Angas Hamer & Fergus Cameron. Are symptoms of ‘hypoglycemia’ in Chronic Fatigue Syndrome (CFS) associated with hypoglycemia or orthostatic intolerance in young people? From: The IACFS/ME 2016 Conference Syllabus.

 

Assessment of Cellular Bioenergetics in Chronic Fatigue Syndrome

Introduction: Abnormalities in bioenergetic function have been cited as one possible cause for chronic fatigue syndrome (CFS). One hypothesis to explain this suggests that CFS may be caused, at least in part, by an acquired mitochondrial dysfunction.

Extracellular flux analysers make real-time, in vitro assessment of cellular energy pathways possible. Using this technology, mitochondrial function can be measured in a variety of cell types in real-time thus increasing our understanding of the role of metabolism in CFS.

Objectives: This project aims to utilise extracellular flux detection technology in order to investigate the cellular bioenergetics of different cell types obtained from CFS patients and healthy controls.

Methods: Mitochondrial stress tests were conducted using skeletal muscle cells and peripheral blood mononuclear cells (PBMCs) derived from CFS patients and controls. During this test mitochondrial complexes are inhibited in turn to modulate respiration so mitochondrial function can be evaluated. The oxygen consumption rate of cells is measured which allows keys parameters of mitochondrial function to be measured and calculated in a single experiment, providing an overall assessment of mitochondrial function. Parameters measured are: basal respiration, maximal respiration and non-mitochondrial respiration. Proton leak, ATP-production and spare respiratory capacity are subsequently able to be calculated using the three measured parameters. CFS patients whose samples were used in these studies were diagnosed using the Fukuda definition.

Results: Results using skeletal muscle cells obtained from CFS patients (n=3) and controls (n=5), indicate that there is no difference in the energy profiles of the skeletal muscle cells of CFS patients in any of the parameters investigated.

Mitochondrial stress test results using PBMCs show CFS PBMCs (n=7) to be significantly lower than control cells (n=10) in all parameters investigated (p≤0.016). Importantly, these results suggest that CFS PBMCs perform closer to their maximum under normal conditions. This means that when CFS PBMCs come under stress they are less able to increase their respiration rate to compensate for the increase in stress.

Conclusions: These findings provide an interesting starting point for investigations into cellular bioenergetics in CFS.

Cara Jasmine Tomas; First year medical science PhD student; Institute of Cellular Medicine, Level 1, William Leech Building, Medical School, Newcastle University, Newcastle Upon-Tyne, NE2 4HH, England; c.j.tomas@ncl.ac.uk
This work was funded by the Medical Research Council and Newcastle University.

 

Source: Cara Tomas, Julia Newton, Audrey Brown, Gina Rutherford, Philip Manning
Newcastle University, UK. Assessment of Cellular Bioenergetics in Chronic Fatigue Syndrome. Poster presentation, IACFS/ME 2016 conference.

Chronic fatigue syndrome: Harvey and Wessely’s (bio)psychosocial model versus a bio(psychosocial) model based on inflammatory and oxidative and nitrosative stress pathways

Abstract:

BACKGROUND: In a recently published paper, Harvey and Wessely put forward a ‘biopsychosocial’ explanatory model for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is proposed to be applicable to (chronic) fatigue even when apparent medical causes are present.

METHODS: Here, we review the model proposed by Harvey and Wessely, which is the rationale for behaviourally oriented interventions, such as cognitive behaviour therapy (CBT) and graded exercise therapy (GET), and compare this model with a biological model, in which inflammatory, immune, oxidative and nitrosative (IO&NS) pathways are key elements.

DISCUSSION: Although human and animal studies have established that the pathophysiology of ME/CFS includes IO&NS pathways, these abnormalities are not included in the model proposed by Harvey and Wessely. Activation of IO&NS pathways is known to induce fatigue and somatic (F&S) symptoms and can be induced or maintained by viral and bacterial infections, physical and psychosocial stressors, or organic disorders such as (auto)immune disorders. Studies have shown that ME/CFS and major depression are both clinical manifestations of shared IO&NS pathways, and that both disorders can be discriminated by specific symptoms and unshared or differentiating pathways. Interventions with CBT/GET are potentially harmful for many patients with ME/CFS, since the underlying pathophysiological abnormalities may be intensified by physical stressors.

CONCLUSIONS: In contrast to Harvey and Wessely’s (bio)psychosocial model for ME/CFS a bio(psychosocial) model based upon IO&NS abnormalities is likely more appropriate to this complex disorder. In clinical practice, we suggest physicians should also explore the IO&NS pathophysiology by applying laboratory tests that examine the pathways involved.

 

Source: Maes M, Twisk FN. Chronic fatigue syndrome: Harvey and Wessely’s (bio)psychosocial model versus a bio(psychosocial) model based on inflammatory and oxidative and nitrosative stress pathways. BMC Med. 2010 Jun 15;8:35. doi: 10.1186/1741-7015-8-35. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2901228/ (Full article)

 

Cellular and molecular mechanisms of interaction between the neuroendocrine and immune systems under chronic fatigue syndrome in experiment

Abstract:

One of the main mechanisms of chronic fatigue syndrome development involves disturbances of interaction between the immune and neuroendocrine systems. The adequate experimental model for the search of these mechanisms is induction of fatigue in animals via the single intraperitoneal administration of synthetic double-stranded RNA – Poly I : C.

Investigation of alterations in cytotoxic and proliferation activities of splenocytcs, the intensity of immunomodulatory cytokines signaling via the sphingomyelin pathways in membrane P2 fraction of the brain cortex, as well as the activity of hypothalamic-pituitary adrenal (HP A) axis in the dynamics of chronic fatigue syndrome in rats has performed. Inhibition of both cytotoxic and proliferative activities of splenocytes during the period of fatigue development has been shown. Priority data concerning the suppression of the activity of neutral sphingomyelinase (nSMase) – the key enzyme of the sphingomyelin cascade – in membranes ofthe cells from the brain cortex on the 3d day after Poly I : C administration to rats have been obtained.

It was found that Poly I : C injection to rats led to disturbed HPA axis functions which was manifested by decreased corticosterone concentration in standard functional assays with ACTH and hydrocortisone administration.

It is suggested that disturbances in interaction between the immune and neuroendocrine systems during development of chronic fatigue syndrome, including alterations in HPA axis activity, are realized both on the level of changes in the activity of immune-competent cells and immediately on membranes of the brain cells.

 

Source: Rybakina EG, Shanin SN, Fomicheva EE, Korneva EA. Cellular and molecular mechanisms of interaction between the neuroendocrine and immune systems under chronic fatigue syndrome in experiment. Ross Fiziol Zh Im I M Sechenova. 2009 Dec;95(12):1324-35. [Article in Russian] https://www.ncbi.nlm.nih.gov/pubmed/20141043

 

Why myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) may kill you: disorders in the inflammatory and oxidative and nitrosative stress (IO&NS) pathways may explain cardiovascular disorders in ME/CFS

Abstract:

There is evidence that disorders in inflammatory and oxidative and nitrosative (IO&NS) pathways and a lowered antioxidant status are important pathophysiological mechanisms underpinning myalgic encephalomyelitis / chronic fatigue syndrome(ME/CFS). Important precipitating and perpetuating factors for ME/CFS are (amongst others) bacterial and viral infections; bacterial translocation due to an increased gut permeability; and psychological stress.

Recently, Jason et al (2006) reported that the mean age of patients with myalgic encephalomyelitis/chronic fatigue syndrome dying from heart failure, i.e. 58.7 years, is significantly lower than the age of those dying from heart failure in the general US population, i.e. 83.1 years. These findings implicate that ME/CFS is a risk factor to cardio-vascular disorder.

This review demonstrates that disorders in various IO&NS pathways provide explanations for the earlier mortality due to cardiovascular disorders in ME/CFS. These pathways are: a) chronic low grade inflammation with extended production of nuclear factor kappa B and COX-2 and increased levels of tumour necrosis factor alpha; b) increased O&NS with increased peroxide levels, and phospholipid oxidation including oxidative damage to phosphatidylinositol; c) decreased levels of specific antioxidants, i.e. coenzyme Q10, zinc and dehydroepiandrosterone-sulphate; d) bacterial translocation as a result of leaky gut; e) decreased omega-3 polyunsatutared fatty acids (PUFAs), and increased omega-6 PUFA and saturated fatty acid levels; and f) the presence of viral and bacterial infections and psychological stressors. The mechanisms whereby each of these factors may contribute towards cardio-vascular disorder in ME/CFS are discussed.

ME/CFS is a multisystemic metabolic-inflammatory disorder. The aberrations in IO&NS pathways may increase the risk for cardiovascular disorders.

 

Source: Maes M, Twisk FN. Why myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) may kill you: disorders in the inflammatory and oxidative and nitrosative stress (IO&NS) pathways may explain cardiovascular disorders in ME/CFS. Neuro Endocrinol Lett. 2009;30(6):677-93. https://www.ncbi.nlm.nih.gov/pubmed/20038921

 

Increased 8-hydroxy-deoxyguanosine, a marker of oxidative damage to DNA, in major depression and myalgic encephalomyelitis / chronic fatigue syndrome

Abstract:

BACKGROUND: There is now evidence that major depression and myalgic encephalomyelitis / chronic fatigue syndrome(ME/CFS) are accompanied by partially overlapping pathophysiological mechanisms, i.e. activation of various inflammatory and oxidative & nitrosative (IO&NS) pathways.

OBJECTIVE: The aim of the present study was to examine the urinary excretion of 8-hydroxy-deoxyguanosine (8-OhdG), a marker of oxidative damage to DNA, in depression; ME/CFS; and depression and ME/CFS.

METHODS: Toward this end, morning urine was sampled for the assays of 8-OHdG and creatinine, in 44 patients with ME/CFS; 25 with major depression; 23 with depression and ME/CFS; and 17 normal controls. Severity of fatigue and somatic symptoms was measured by means of the Fibromyalgia and CFS Rating (FF) scale.

RESULTS: We found that 49.0% of the variance in the urinary excretion of 8-OHdG was predicted by the regression on creatinine. Consequently, the urinary 8-OHdG excretion should be expressed as the residualized 8-OHdG values after partialling out the effects of creatinine and not by computing the 8-OHdG / creatinine ratio. We found that the residualized urinary excretion of 8-OHdG (adjusted for creatinine) was significantly higher in patients with depression and ME/CFS than in normal controls and all other patients. In the patient group, there were significant correlations between the urinary 8-OHdG and the total score on the FF scale and sadness and flu-like malaise.

CONCLUSIONS: The findings show increased oxidatively generated DNA damage in patients with major depression and ME/CFS and, therefore, further extent the role played by IO&NS pathways in the pathophysiology of both disorders. Since oxidatively damage to DNA is a risk factor for atherosclerosis and neurodegeneration, our results also explain previous findings on increased cardiovascular morbidity in depression and ME/CFS, and neurodegenerative processes in depression.

 

Source: Maes M, Mihaylova I, Kubera M, Uytterhoeven M, Vrydags N, Bosmans E. Increased 8-hydroxy-deoxyguanosine, a marker of oxidative damage to DNA, in major depression and myalgic encephalomyelitis / chronic fatigue syndrome. Neuro Endocrinol Lett. 2009;30(6):715-22. https://www.ncbi.nlm.nih.gov/pubmed/20035260

 

Immunological similarities between cancer and chronic fatigue syndrome: the common link to fatigue?

Abstract:

Cancer and chronic fatigue syndrome (CFS) are both characterised by fatigue and severe disability. Besides fatigue, certain aspects of immune dysfunctions appear to be present in both illnesses. In this regard, a literature review of overlapping immune dysfunctions in CFS and cancer is provided.

Special emphasis is given to the relationship between immune dysfunctions and fatigue. Abnormalities in ribonuclease (RNase) L and hyperactivation of nuclear factor kappa beta (NF-kappaB) are present in CFS and in prostate cancer. Malfunctioning of natural killer (NK) cells has long been recognised as an important factor in the development and reoccurrence of cancer, and has been documented repeatedly in CFS patients.

The dysregulation of the RNase L pathway, hyperactive NF-kappaB leading to disturbed apoptotic mechanisms and oxidative stress or excessive nitric oxide, and low NK activity may play a role in the two diseases and in the physiopathology of the common symptom fatigue. However, in cancer the relation between the immune dysfunctions and fatigue has been poorly studied. Immunological abnormalities to such as a dysregulated RNase L pathway, hyperactive NF-kappaB, increased oxidative stress and reduced NK cytotoxicity, among others, are present in both diseases.

These anomalies may be part of the physiopathology of some of the common complaints, such as fatigue. Further studies to confirm the hypotheses given here are warranted.

 

Source: Meeus M, Mistiaen W, Lambrecht L, Nijs J. Immunological similarities between cancer and chronic fatigue syndrome: the common link to fatigue? Anticancer Res. 2009 Nov;29(11):4717-26. http://ar.iiarjournals.org/content/29/11/4717.long (Full article)