Category: Pathogenesis

Acute encephalopathy induced in cats with a stealth virus isolated from a patient with chronic fatigue syndrome

Abstract:

A simian cytomegalovirus-related stealth virus, isolated from a patient with the chronic fatigue syndrome, induced an acute neurological illness when inoculated into cats. Histological examination of brain tissue showed foci of cells with cytoplasmic vacuolization and an absence of any inflammatory reaction. Electron microscopy confirmed the presence of herpes-like viral particles and viral-like products in the brain of an inoculated animal. These findings support the role of stealth viruses in the pathogenesis of human neurological diseases and provide an animal model to evaluate potential antiviral therapy.

 

Source: Martin WJ, Glass RT. Acute encephalopathy induced in cats with a stealth virus isolated from a patient with chronic fatigue syndrome. Pathobiology. 1995;63(3):115-8. http://www.ncbi.nlm.nih.gov/pubmed/8821627

 

Chronic fatigue syndrome. 1: Etiology and pathogenesis

Abstract:

Chronic fatigue syndrome (CFS) is a disorder of unknown etiology characterized by debilitating fatigue and other somatic and neuropsychiatric symptoms. A range of heterogeneous clinical and laboratory findings have been reported in patients with CFS. Various theories have been proposed to explain the underlying pathophysiologic processes but none has been proved.

Research findings of immunologic dysfunction and neuroendocrine changes suggest the possible dysregulation of interactions between the nervous system and the immune system. Without a clear understanding of its etiopathogenesis, CFS has no definitive treatment.

Management approaches have been necessarily speculative, and they have evolved separately in a number of medical and nonmedical disciplines. The results of several controlled treatment studies have been inconclusive. An accurate case definition identifying homogeneous subtypes of CFS is needed. The integration of medical and psychologic treatment modalities and the use of both biologic and psychologic markers to evaluate treatment response will enhance future treatment strategies.

 

Source: Farrar DJ, Locke SE, Kantrowitz FG. Chronic fatigue syndrome. 1: Etiology and pathogenesis. Behav Med. 1995 Spring;21(1):5-16. http://www.ncbi.nlm.nih.gov/pubmed/7579775

 

Serum concentrations of 2′,5′-oligoadenylate synthetase, neopterin, and beta-glucan in patients with chronic fatigue syndrome and in patients with major depression

Chronic fatigue syndrome is characterised by debilitating severe fatigue persisting for more than six months. Furthermore, it is associated with physical symptoms, such as mild fever, sore throat, arthralgia, and myalgia, as well as psychological symptoms such as headache, insomnia, depressive state, and neuropsychiatric symptoms. It has often been claimed that the onset of chronic fatigue syndrome follows an infection or infection-like illness; hence a certain microorganism(s) or virus may cause it. Another possible candidate for inducing chronic fatigue syndrome is cellular or humoral immune dysfunction, which has been found in patients with the disease. There is controversy also as to whether or not chronic fatigue syndrome and major depression (mood disorder) represent different entities.

Mild fever, pharyngitis, and lymphadenopathy, which are suggestive of the existence of inflammation, are often associated with chronic fatigue syndrome, but the peripheral leucocyte count, erythrocyte sedimentation rate, and C-reactive protein concentration are usually normal in patients with chronic fatigue syndrome. Hence, it is possible that certain cytokines may produce the symptoms in patients with chronic fatigue syndrome and, possibly, those with major depression. For example, interferon is known to cause fever, fatigue, and psychoneurological abnormalities. We conducted this study to clarify whether or not 2′,5′-oligoadenylate synthetase (2,5-AS), neopterin, adenosine deaminase, endotoxin, or B-glucan participate in the pathogenesis of chronic fatigue syndrome.

You can read the rest of this article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1073106/pdf/jnnpsyc00038-0135b.pdf

 

Source: Matsuda J, Gohchi K, Gotoh N. Serum concentrations of 2′,5′-oligoadenylate synthetase, neopterin, and beta-glucan in patients with chronic fatigue syndrome and in patients with major depression. J Neurol Neurosurg Psychiatry. 1994 Aug;57(8):1015-6. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1073106/

 

Upregulation of the 2-5A synthetase/RNase L antiviral pathway associated with chronic fatigue syndrome

Abstract:

Levels of 2′,5′-oligoadenylate (2-5A) synthetase, bioactive 2-5A, and RNase L were measured in extracts of peripheral blood mononuclear cells (PBMCs) from 15 individuals with chronic fatigue syndrome (CFS) before and during therapy with the biological response modifier poly(I).poly(C12U) and were compared with levels in healthy controls.

Patients differed significantly from controls in having a lower mean basal level of latent 2-5A synthetase (P < .0001), a higher pretreatment level of bioactive 2-5A (P = .002), and a higher level of pretherapy RNase L activity (P < .0001). PBMC extracts from 10 persons with CFS had a mean basal level of activated 2-5A synthetase higher than the corresponding control value (P = .009). All seven pretherapy PBMC extracts tested were positive for the replication of human herpesvirus 6 (HHV-6).

Therapy with poly(I).poly(C12U) resulted in a significant decrease in HHV-6 activity (P < .01) and in downregulation of the 2-5A synthetase/RNase L pathway in temporal association with clinical and neuropsychological improvement. The upregulated 2-5A pathway in CFS before therapy is consistent with an activated immune state and a role for persistent viral infection in the pathogenesis of CFS. The response to therapy suggests direct or indirect antiviral activity of poly(I).poly(C12U) in this situation.

 

Source: Suhadolnik RJ, Reichenbach NL, Hitzges P, Sobol RW, Peterson DL, Henry B, Ablashi DV, Müller WE, Schröder HC, Carter WA, et al. Upregulation of the 2-5A synthetase/RNase L antiviral pathway associated with chronic fatigue syndrome. Clin Infect Dis. 1994 Jan;18 Suppl 1:S96-104. http://www.ncbi.nlm.nih.gov/pubmed/8148461

 

Studies on enterovirus in patients with chronic fatigue syndrome

Abstract:

A large study on 121 patients with the chronic fatigue syndrome (CFS) that examined muscle biopsy samples for enterovirus by means of polymerase chain reaction analysis was carried out. The results were compared with those obtained from 101 muscle biopsy specimens from patients with a variety of other neuromuscular disorders (OND), including neurogenic atrophies, dystrophies, and mitochondrial, metabolic, and endocrine myopathies.

Thirty-two (26.4%) of the biopsy specimens from the group of patients with CFS were positive, compared with 20 (19.8%) from the group of patients with OND, a difference that was not significant.

This finding is in contrast to those of our previous smaller study in which significantly more patients with CFS than control subjects (53% [32 of 60] vs. 15% [6 of 41]) had enterovirus RNA sequences in their muscle. It was concluded that it is unlikely that persistent enterovirus infection plays a pathogenetic role in CFS, although an effect in initiating the disease process cannot be excluded.

 

Source: Gow JW, Behan WM, Simpson K, McGarry F, Keir S, Behan PO. Studies on enterovirus in patients with chronic fatigue syndrome. Clin Infect Dis. 1994 Jan;18 Suppl 1:S126-9. http://www.ncbi.nlm.nih.gov/pubmed/8148439

 

Pathogenic tracks in fatigue syndromes

Abstract:

This review analyses the recent literature devoted to two related fatigue syndromes: chronic fatigue syndrome (CFS) and acute onset postviral fatigue syndrome (PVFS). The articles are grouped into five pathogenic tracks: infectious agents, immune system, skeletic muscle, hypothalamo-pituitary-adrenal (HPA) axis and psychiatric factors.

Although a particular infectious agent is unlikely to be responsible for all CFS cases, evidence is shown that host-parasite relationships are modified in a large proportion of patients with chronic fatigue. Antibody titres against infectious agents are often elevated and replication of several viruses could be increased.

Chronic activation of the immune system is also observed and could be due to the reactivation of persistent or latent infectious agents such as herpes viruses (i.e. HHV-6) or enteroviruses. It could also be favorised by an impaired negative feedback of the HPA axis on the immune system.

A model is proposed where the abnormalities of the HPA axis are primary events and are mainly responsible for a chronic activation of the immune system which in turn induces an increased replication of several viruses under the control of cellular transcription factors. These replicating viruses together with cytokines such as TNF-alpha would secondarily induce functional disorders of muscle and several aspects of asthenia itself.

 

Source: Moutschen M, Triffaux JM, Demonty J, Legros JJ, Lefèbvre PJ. Pathogenic tracks in fatigue syndromes. Acta Clin Belg. 1994;49(6):274-89. http://www.ncbi.nlm.nih.gov/pubmed/7871934

 

Human herpesvirus 6 and chronic fatigue syndrome

Abstract:

The cause of chronic fatigue syndrome (CFS) is still enigmatic. Using indirect immunofluorescence testing for measuring antibody against human herpesvirus 6 (HHV-6), this study investigated the association of CFS with infection by HHV-6. Seventeen patients (group A) fulfilling the Centers for Disease Control (CDC) definition for CFS were compared with eight patients (group B) with chronic fatigue but not meeting the CDC criteria.

No significant difference was found between the two groups for 30 parameters including sex, age, exposure to children and serology for Epstein-Barr virus, cytomegalovirus, herpes simplex virus, and toxoplasma. Univariate analysis showed that patients in group A complained more frequently of a sore throat, headache and of recurrent type of fatigue.

These three parameters are discriminant in identifying patients who will meet the CDC case definition of CFS. The titre of antibody against HHV-6 in group A (1:99) was significantly higher than in group B (1:15) (P=0.007). Elevated HHV-6 titres suggests that this virus could be a cofactor in the pathogenesis of CFS.

 

Source: Eymard D, Lebel F, Miller M, Turgeon F. Human herpesvirus 6 and chronic fatigue syndrome. Can J Infect Dis. 1993 Jul;4(4):199-202. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250792/  (Full article)

 

Enteroviruses and postviral fatigue syndrome

Abstract:

Postviral fatigue syndrome (PFS) occurs both in epidemics and sporadically. Many of the original epidemics were related to poliomyelitis outbreaks which either preceded or followed them.

The core clinical symptoms are always the same: severe fatigue made worse by exercise, myalgia, night sweats, atypical depression and excessive sleep. The other common symptoms include dysequilibrium disorders and irritable bowel syndrome.

We have detected enteroviral genome sequences in muscle biopsies from cases of PFS, using specific enteroviral oligonucleotide primers in the polymerase chain reaction (PCR). In addition, whole virus particles can be demonstrated in PCR-positive muscle, using solid-phase immuno-electron microscopy.

An increase in the number and size of muscle mitochondria was found in 70% of PFS cases, suggesting an abnormality in metabolic function. Evidence of hypothalamic dysfunction was present, particularly involving 5-hydroxytryptamine metabolism.

A putative model of PFS, based on persistent enteroviral infection in laboratory mice, revealed resolving inflammatory lesions in muscle with, however, a marked increase in the production of certain cytokines in the brain. This model may help to explain the pathogenesis of PFS.

 

Source: Behan PO, Behan WM, Gow JW, Cavanagh H, Gillespie S. Ciba Found Symp. 1993;173:146-54; discussion 154-9. http://www.ncbi.nlm.nih.gov/pubmed/8387908

 

Chronic fatigue syndrome–study of 51 cases treated at the Second Tokyo National Hospital

Abstract:

Fifty-one patients with chronic fatigue syndrome (CFS) were studied. Tender points, which are a characteristic clinical feature of fibromyalgia, were found in all but two of the patients at 11.4 points (mean) per patient. IgG antibody titers to EB virus viral capsid antigen were more elevated in the CFS patient group compared to that of the control (p < 0.0015). IgG antibody titers to HHV-6 were not higher in the patient group. NK cell activity was not more decreased in the patient group, whereas, the mean number of NK cells was lower (p < 0.005) in the patient group, when CD57 was used as the NK cell marker. Viral infections and/or disorders in cellular immunity may be important factors in the pathogenesis of CFS.

 

Source: Nishikai M. Chronic fatigue syndrome–study of 51 cases treated at the Second Tokyo National Hospital. Nihon Rinsho. 1992 Nov;50(11):2641-7. [Article in Japanese] http://www.ncbi.nlm.nih.gov/pubmed/1337560

 

Overview of our patients with chronic fatigue syndrome (CFS) from the pathoetiological aspects

Abstract:

We interviewed 285 patients who visited our department claiming with a complaint of chronic fatigue syndrome (CFS) and subsequently diagnosed 55 as having CFS, according to the criteria for CFS of the centers for disease control (CDC). We measured various virus antibody titers, 2-5, adenylate synthetase levels in the serum lymphocyte subset in blood, employing a double staining technique with monoclonal antibodies. In this paper, we pathoetiology of CFS, based on our findings and other researchers’ is discussed.

 

Source: Matsuda J, Gohchi K. Overview of our patients with chronic fatigue syndrome (CFS) from the pathoetiological aspects. Nihon Rinsho. 1992 Nov;50(11):2635-40. [Article in Japanese] http://www.ncbi.nlm.nih.gov/pubmed/1287240