Category: Pathophysiology

The role of enterovirus in chronic fatigue syndrome

Abstract:

Two and a half decades after coining of the term chronic fatigue syndrome (CFS), the diagnosis of this illness is still symptom based and the aetiology remains elusive. Enteroviruses are well known causes of acute respiratory and gastrointestinal infections, with tropism for the central nervous system, muscles, and heart.

Initial reports of chronic enteroviral infections causing debilitating symptoms in patients with CFS were met with skeptism, and had been largely forgotten for the past decade. Observations from in vitro experiments and from animal models clearly established a state of chronic persistence through the formation of double stranded RNA, similar to findings reported in muscle biopsies of patients with CFS.

Recent evidence not only confirmed the earlier studies, but also clarified the pathogenic role of viral RNA through antiviral treatment. This review summarises the available experimental and clinical evidence that supports the role of enterovirus in chronic fatigue syndrome.

 

Source: Chia JK. The role of enterovirus in chronic fatigue syndrome. J Clin Pathol. 2005 Nov;58(11):1126-32. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1770761/ (Full article)

 

Oxidative stress levels are raised in chronic fatigue syndrome and are associated with clinical symptoms

Abstract:

The aetiology of chronic fatigue syndrome (CFS) is unknown; however, recent evidence suggests excessive free radical (FR) generation may be involved. This study investigated for the first time levels of 8-iso-prostaglandin-F(2 alpha)-isoprostanes alongside other plasma markers of oxidative stress in CFS patients and control subjects.

Forty-seven patients (18 males, 29 females, mean age 48 [19–63] years) who fulfilled the Centres for Disease Control classification for CFS and 34 healthy volunteers (13 males, 21 females, 46 [19–63] years) were enrolled in the study. The CFS patients were divided into two groups; one group had previously defined cardiovascular (CV) risk factors of obesity and hypertension (group 1) and the second were normotensive and nonobese (group 2). Patients had significantly increased levels of isoprostanes (group 1, P=0.007; group 2, P=0.03, unpaired t test compared to controls) and oxidised low-density lipoproteins (group 2, P=0.02) indicative of a FR attack on lipids. CFS patients also had significantly lower high-density lipoproteins (group 1, P=0.011; group 2, P=0.005).

CFS symptoms correlated with isoprostane levels, but only in group 2 low CV risk CFS patients (isoprostanes correlated with; total symptom score P=0.005; joint pain P=0.002; postexertional malaise P=0.027, Pearson). This is the first time that raised levels of the gold standard measure of in vivo oxidative stress (isoprostanes) and their association with CFS symptoms have been reported.

 

Source: Kennedy G, Spence VA, McLaren M, Hill A, Underwood C, Belch JJ. Oxidative stress levels are raised in chronic fatigue syndrome and are associated with clinical symptoms. Free Radic Biol Med. 2005 Sep 1;39(5):584-9. http://www.ncbi.nlm.nih.gov/pubmed/16085177

 

Urinary and plasma organic acids and amino acids in chronic fatigue syndrome

Abstract:

Previous work by others have suggested the occurrence of one or more chemical or metabolic ‘markers’ for ME/CFS including specific amino acids and organic acids and a number of unidentified compounds (CFSUM1, CFSUM2). We have shown elsewhere that CFSUM1 is partially derivatised pyroglutamic acid and CFSUM2 partially derivatised serine and have suggested and demonstrated that the analytical methods used were unsuitable to identify or to accurately quantify urinary metabolites. We have now made a detailed analysis of plasma and urinary amino acids and of urinary organic acids from patients with ME/CFS and from three control groups.

Fasting blood plasma and timed urine samples were obtained from 31 patients with CFS, 31 age and sex-matched healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Plasma and urinary amino acids and urinary organic acids were determined using established and validated methods and data compared by statistical analysis. None of the previously reported abnormalities in urinary amino acids or of organic acids could be confirmed.

Results however provide some evidence in patients with ME/CFS for underlying inflammatory disease and for reduced intramuscular collagen with a lowered threshold for muscle micro-injury. These factors in combination may provide a basis for the fatigue and muscle pain that are the major symptoms in these patients.

 

Source: Jones MG, Cooper E, Amjad S, Goodwin CS, Barron JL, Chalmers RA. Urinary and plasma organic acids and amino acids in chronic fatigue syndrome. Clin Chim Acta. 2005 Nov;361(1-2):150-8. http://www.ncbi.nlm.nih.gov/pubmed/15992788

 

Gray matter volume reduction in the chronic fatigue syndrome

Abstract:

The chronic fatigue syndrome (CFS) is a disabling disorder of unknown etiology. The symptomatology of CFS (central fatigue, impaired concentration, attention and memory) suggests that this disorder could be related to alterations at the level of the central nervous system. In this study, we have used an automated and unbiased morphometric technique to test whether CFS patients display structural cerebral abnormalities.

We mapped structural cerebral morphology and volume in two cohorts of CFS patients (in total 28 patients) and healthy controls (in total 28 controls) from high-resolution structural magnetic resonance images, using voxel-based morphometry. Additionally, we recorded physical activity levels to explore the relation between severity of CFS symptoms and cerebral abnormalities.

We observed significant reductions in global gray matter volume in both cohorts of CFS patients, as compared to matched control participants. Moreover, the decline in gray matter volume was linked to the reduction in physical activity, a core aspect of CFS. These findings suggest that the central nervous system plays a key role in the pathophysiology of CFS and point to a new objective and quantitative tool for clinical diagnosis of this disabling disorder.

 

Source: de Lange FP, Kalkman JS, Bleijenberg G, Hagoort P, van der Meer JW, Toni I. Gray matter volume reduction in the chronic fatigue syndrome. Neuroimage. 2005 Jul 1;26(3):777-81. Epub 2005 Apr 7. http://www.ncbi.nlm.nih.gov/pubmed/15955487

 

Green tea extract and catechin ameliorate chronic fatigue-induced oxidative stress in mice

Abstract:

Chronic fatigue syndrome (CFS) is an illness characterized by persistent and relapsing fatigue, often accompanied by numerous symptoms involving various body systems. The etiology of CFS remains unclear, but a number of studies have shown that oxidative stress may be involved in its pathogenesis. The present study was designed to investigate the protective effect of green tea extract (GTE) and catechin in the mouse model of CFS.

Animals were subjected to a forced swimming test session of 6 minutes every day for 7 days; a significant increase in immobility time on successive days represented the CFS in mice. Biochemical analysis revealed that the chronic swim test significantly increased lipid peroxidation levels and decreased glutathione levels in mouse whole-brain homogenate.

Treatment with GTE (25 or 50 mg/kg, i.p.) and catechin (50 or 100 mg/kg, i.p.) for 7 days reversed the increase in immobility time. Protection was correlated with the lowered levels of lipid peroxidation and restoration of reduced glutathione levels in the brains of fatigued mice. These findings strongly suggest the pivotal role of oxidative stress in the pathophysiology of CFS and that GTE and catechin could be used as potential agents in the management of CFS and warrant the inclusion of GTE and catechin in the treatment regimen of CFS patients.

 

Source: Singal A, Kaur S, Tirkey N, Chopra K. Green tea extract and catechin ameliorate chronic fatigue-induced oxidative stress in mice. J Med Food. 2005 Spring;8(1):47-52. http://www.ncbi.nlm.nih.gov/pubmed/15857209

 

Are attention deficit hyperactivity disorder and chronic fatigue syndrome allergy related? What is fibromyalgia?

Abstract:

Despite the progress made in the field of allergy-immunology in recent years, there are a group of diseases that the allergist-immunologist may be called on to manage in which their precise etiologies have not been identified but that appear to be initiated or exacerbated by allergic mechanisms. Attention deficit hyperactivity disorder (ADHD), chronic fatigue syndrome (CFS), and fibromyalgia (FM) fall into this category of disorders.

Although the precise etiology of ADHD still remains unknown, the most prevalent theory is that it represents a neurobiologically based developmental disability leading to inadequate production of the neurotransmitter dopamine.

In patients with CFS, there appears to be a fundamental dysfunction of the neuroendocrine-immunological system with deficiencies of immunological and neurological function, which, together with chronic viral infection, may lead to a sequence of events responsible for the symptoms of this disorder.

FM appears to be a variant of CFS with a predominance of hypothalamic pituitary axis dysfunction. The disorder is characterized by chronic widespread pain and the finding of 11/18 tender points on examination.

Now, there is emerging evidence to suggest that adverse reactions to foods or food components also may be associated with behavioral disturbances that may play a role in each of these disorders. An understanding of the interactive responses involved in the neuroendocrine-immunological network is essential for a comprehension of the pathophysiology of ADHD, CFS, and FM and the role of allergies appears to be an important triggering event in each of the disorders.

 

Source: Bellanti JA, Sabra A, Castro HJ, Chavez JR, Malka-Rais J, de Inocencio JM. Are attention deficit hyperactivity disorder and chronic fatigue syndrome allergy related? What is fibromyalgia? Allergy Asthma Proc. 2005 Jan-Feb;26(1):19-28. http://www.ncbi.nlm.nih.gov/pubmed/15813284

 

 

Brain 5-HT1A receptor binding in chronic fatigue syndrome measured using positron emission tomography and [11C]WAY-100635

Abstract:

BACKGROUND: Research from neuroendocrine challenge and other indirect studies has suggested increased central 5-HT function in chronic fatigue syndrome (CFS) and increased 5-HT1A receptor sensitivity. We assessed brain 5-HT1A receptor binding potential directly using the specific radioligand [11C]WAY-100635 and positron emission tomography (PET).

METHODS: We selected 10 patients from a tertiary referral clinic who fulfilled the CDC consensus criteria for CFS. To assemble a homogenous group and avoid confounding effects, we enrolled only subjects who were completely medication-free and did not have current comorbid psychiatric illness. We also scanned 10 healthy control subjects.

RESULTS: There was a widespread reduction in 5-HT1A receptor binding potential in CFS relative to control subjects. This was particularly marked in the hippocampus bilaterally, where a 23% reduction was observed.

CONCLUSIONS: There is evidence of decreased 5-HT1A receptor number or affinity in CFS. This may be a primary feature of CFS, related to the underlying pathophysiology, or a finding secondary to other processes, such as previous depression, other biological changes or the behavioral consequences of CFS.

 

Source: Cleare AJ, Messa C, Rabiner EA, Grasby PM. Brain 5-HT1A receptor binding in chronic fatigue syndrome measured using positron emission tomography and [11C]WAY-100635. Biol Psychiatry. 2005 Feb 1;57(3):239-46. http://www.ncbi.nlm.nih.gov/pubmed/15691524

 

Do vasoactive neuropeptides and heat shock proteins mediate fatigue-related autoimmune disorders?

Abstract:

Autoimmune dysfunction of certain vasoactive neuropeptides may be implicated in a range of disorders associated with fatigue like states (chronic fatigue syndrome, Gulf War syndrome) and even sudden infant death syndrome. These substances have neurotrophic, neuroregulatory, and neurotransmission functions, as well as that of immune modulators and hormones. They exert significant control over carbohydrate and lipid metabolism.

The hypothesis is that because these substances have vital and indispensable roles in cellular processes, loss or compromise of these roles would lead to predictable and severe cellular and systemic effects. The important roles of certain VNs make them a vulnerable target for autoimmune dysfunction. They are known to be associated with heat shock proteins for intracellular functioning with which they may form immunostimulating complexes. While peptide-HSP complexes are a relatively new area for research, this paper asserts that attention could be focused on these substances and complexes in an effort to elucidate a number of perplexing fatigue-associated disorders.

 

Source: Staines DR. Do vasoactive neuropeptides and heat shock proteins mediate fatigue-related autoimmune disorders? Med Hypotheses. 2005;64(3):539-42. http://www.ncbi.nlm.nih.gov/pubmed/15617862

 

Reduction of serotonin transporters of patients with chronic fatigue syndrome

Abstract:

To assess the involvement of serotonin in the symptoms of chronic fatigue syndrome, we investigated the serotonergic neurotransmitter system of chronic fatigue syndrome patients by the positron emission tomography (PET).

Here we show that the density of serotonin transporters (5-HTTs) in the brain, as determined by using a radiotracer, [C](+)McN5652, was significantly reduced in the rostral subdivision of the anterior cingulate as compared with that in normal volunteers. This subdivision is different from that in the dorsal anterior cingulate in which binding potential values of individual patient showed a weak negative correlation with self-reported pain score of the patients.

Therefore, an alteration of serotonergic system in the rostral anterior cingulate plays a key role in pathophysiology of chronic fatigue syndrome.

 

Source: Yamamoto S, Ouchi Y, Onoe H, Yoshikawa E, Tsukada H, Takahashi H, Iwase M, Yamaguti K, Kuratsune H, Watanabe Y. Reduction of serotonin transporters of patients with chronic fatigue syndrome. Neuroreport. 2004 Dec 3;15(17):2571-4. http://www.ncbi.nlm.nih.gov/pubmed/15570154

 

Diminished central activation during maximal voluntary contraction in chronic fatigue syndrome

Abstract:

OBJECTIVE: We have investigated whether central activation failure (CAF) is increased during local muscle fatigue in chronic fatigue syndrome (CFS).

METHODS: Fourteen female CFS patients and 14 age-matched healthy female controls made a 2 min sustained maximal voluntary contraction (MVC) of the biceps brachii muscle. Before, during, and after sustained MVC, electrical endplate stimulation was applied. Force and 5 channel surface EMG (sEMG) were registered.

RESULTS: Although force responses upon stimulation during rest did not differ between patients and controls, MVC was significantly lower in patients. Already at the beginning of sustained MVC, CFS patients showed significantly larger CAF than controls (36.5+/-17.0% and 12.9+/-13.3%, respectively). For all individual patients mean CAF over the first 45 s was higher than 30%, while it was below 30% for all controls. Less peripheral fatigue in patients was demonstrated by the changes in muscle fibre conduction velocity and the differences between force responses before and after contraction.

CONCLUSIONS: Central activation is diminished in CFS patients. Possible causes include changed perception, impaired concentration, reduced effort and physiologically defined changes, e.g. in the corticospinal excitability or the concentration of neurotransmitters. As a consequence, demands on the muscle are lower, resulting in less peripheral fatigue.

SIGNIFICANCE: CFS patients show reduced central activation during MVC. The underlying pathophysiological processes remain still to be determined.

 

Source: Schillings ML, Kalkman JS, van der Werf SP, van Engelen BG, Bleijenberg G, Zwarts MJ. Diminished central activation during maximal voluntary contraction in chronic fatigue syndrome. Clin Neurophysiol. 2004 Nov;115(11):2518-24. http://www.ncbi.nlm.nih.gov/pubmed/15465441