EBV/HHV-6A dUTPases contribute to myalgic encephalomyelitis/chronic fatigue syndrome pathophysiology by enhancing TFH cell differentiation and extrafollicular activities.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic, debilitating, multisystem illness of unknown etiology for which no cure and no diagnostic tests are available. Despite increasing evidence implicating EBV and human herpesvirus 6A (HHV-6A) as potential causative infectious agents in a subset of patients with ME/CFS, few mechanistic studies address a causal relationship. In this study we examined a large ME/CFS cohort and controls and demonstrated a significant increase in activin A and IL-21 serum levels, which correlated with seropositivity for antibodies against the EBV and HHV-6 protein deoxyuridine triphosphate nucleotidohydrolase (dUTPases) but no increase in CXCL13. These cytokines are critical for T follicular helper (TFH) cell differentiation and for the generation of high-affinity antibodies and long-lived plasma cells. Notably, ME/CFS serum was sufficient to drive TFH cell differentiation via an activin A-dependent mechanism. The lack of simultaneous CXCL13 increase with IL-21 indicates impaired TFH function in ME/CFS. In vitro studies revealed that virus dUTPases strongly induced activin A secretion while in vivo, EBV dUTPase induced the formation of splenic marginal zone B and invariant NKTFH cells. Together, our data indicate abnormal germinal center (GC) activity in participants with ME/CFS and highlight a mechanism by which EBV and HHV6 dUTPases may alter GC and extrafollicular antibody responses.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Induced by Repeated Forced Swimming in Mice.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by disabling fatigue of at least 6 months, in addition to symptoms such as muscle pain and muscle weakness. There is no treatment provides long-term benefits to most patients. Recently, clinical research suggested the involvement of pyruvate dehydrogenase (PDH) in ME/CFS. PDH is a crucial enzyme in the mitochondria matrix that links glycolysis to the tricarboxylic acid cycle and oxidative phosphorylation. However, it is little known whether PDH could be a therapeutic target. The purpose of this study was to establish ME/CFS in mice and to investigate the involvement of PDH in ME/CFS. To induce the chronic fatigue in mice, a repeated forced swimming test was conducted. To evaluate fatigue, we measured immobility time in forced swimming test and starting time of grooming. An open field test was conducted on day 8. After 25 d of the forced swimming test, the mitochondrial fraction in gastrocnemius muscle was isolated and PDH activity was measured. Moreover, we evaluated the effect of PDH activation by administering sodium dichloroacetate (DCA). In ME/CFS mice group, the immobility time and starting time of grooming increased time-dependently. In addition, the moved distance was decreased in ME/CFS mice. PDH activity was decreased in the mitochondrial fraction of the gastrocnemius muscle of the forced swimming group. DCA treatment may be beneficial in preventing fatigue-like behavior in ME/CFS. These findings indicate that ME/CFS model was established in mice and that a decrease in mitochondrial PDH activity is involved with the symptom of ME/CFS.

Genetic evaluation of AMPD1, CPT2, and PGYM metabolic enzymes in patients with chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a disease that can seriously impair one's quality of life; patients complain of excessive fatigue and myalgia following physical exertion. This disease may be associated with abnormalities in genes affecting exercise tolerance and physical performance. Adenosine monophosphate deaminase (AMPD1), carnitine palmitoyltransferase II (CPT2), and the muscle isoform of glycogen phosphorylase (PYGM) genes provide instructions for producing enzymes that play major roles in energy production during work. The aim of this study was to look for evidence of genotype-associated excessive muscle fatigue. Three metabolic genes (AMPD1, CPT2, and PYGM) were therefore fully sequenced in 17 Italian patients with CFS. We examined polymorphisms known to alter the function of these metabolic genes, and compared their genotypic distributions in CFS patients and 50 healthy controls using chi-square tests and odds ratios. One-way analysis of variance with F-ratio was carried out to determine the associations between genotypes and disease severity using CF scores. No major genetic variations between patients and controls were found in the three genes studied, and we did not find any association between these genes and CFS. In conclusion, variations in AMPD1, CPT2, and PGYM genes are not associated with the onset, susceptibility, or severity of CFS.

Genetic variation in catechol-O-methyltransferase modifies effects of clonidine treatment in chronic fatigue syndrome.

Clonidine, an α2-adrenergic receptor agonist, decreases circulating norepinephrine and epinephrine, attenuating sympathetic activity. Although catechol-O-methyltransferase (COMT) metabolizes catecholamines, main effectors of sympathetic function, COMT genetic variation effects on clonidine treatment are unknown. Chronic fatigue syndrome (CFS) is hypothesized to result in part from dysregulated sympathetic function. A candidate gene analysis of COMT rs4680 effects on clinical outcomes in the Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial (NorCAPITAL), a randomized double-blinded clonidine versus placebo trial, was conducted (N=104). Patients homozygous for rs4680 high-activity allele randomized to clonidine took 2500 fewer steps compared with placebo (Pinteraction=0.04). There were no differences between clonidine and placebo among patients with COMT low-activity alleles. Similar gene-drug interactions were observed for sleep (Pinteraction=0.003) and quality of life (Pinteraction=0.018). Detrimental effects of clonidine in the subset of CFS patients homozygous for COMT high-activity allele warrant investigation of potential clonidine-COMT interaction effects in other conditions.

ERK1/2, MEK1/2 and p38 downstream signalling molecules impaired in CD56 dim CD16+ and CD56 bright CD16 dim/- natural killer cells in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis patients.

BACKGROUND: Natural Killer (NK) cell effector functions are dependent on phosphorylation of the mitogen-activated protein kinases (MAPK) pathway to produce an effective immune response for the clearance of target cells infected with viruses, bacteria or malignantly transformed cells. Intracellular signals activating NK cell cytokine production and cytotoxic activity are propagated through protein phosphorylation of MAPKs including MEK1/2, ERK1/2, p38 and JNK. Reduced NK cell cytotoxic activity is consistently reported in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) patients and intracellular signalling by MAPK in NK cells remains to be investigated. Therefore, the purpose of this paper was to investigate MAPK downstream signalling molecules in NK cell phenotypes from CFS/ME patients. METHODS: Flow cytometric protocols were used to measure phosphorylation of the MAPK pathway in CD56(bright)CD16(dim/-) and CD56(dim)CD16(+) NK cells following stimulation with K562 tumour cells or phorbol-12-myristate-13-acetate plus ionomycin. NK cell cytotoxic activity, degranulation, lytic proteins and cytokine production were also measured as markers for CD56(bright)CD16(dim/-) and CD56(dim)CD16(+) NK cell function using flow cytometric protocols. RESULTS: CFS/ME patients (n = 14) had a significant decrease in ERK1/2 in CD56(dim)CD16(+) NK cells compared to the non-fatigued controls (n = 11) after incubation with K562 cells. CD56(bright)CD16(dim/-) NK cells from CFS/ME patients had a significant increase in MEK1/2 and p38 following incubation with K562 cells. CONCLUSIONS: This is the first study to report significant differences in MAPK intracellular signalling molecules in CD56(dim)CD16(+) and CD56(bright)CD16(dim/-) NK cells from CFS/ME patients. The current results highlight the importance of intracellular signalling through the MAPK pathway for synergistic effector function of CD56(dim)CD16(+) and CD56(bright)CD16(dim/-) NK cells to ensure efficient clearance of target cells. In CFS/ME patients, dysfunctional MAPK signalling may contribute to reduced NK cell cytotoxic activity.

Tryptophan hydroxylase-2: an emerging therapeutic target for stress disorders.

Serotonin (5-HT) has been long recognized to modulate the stress response, and dysfunction of 5-HT has been implicated in numerous stress disorders. Accordingly, the 5-HT system has been targeted for the treatment of stress disorders. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in 5-HT synthesis, and the recent identification of a second, neuron-specific TPH isoform (TPH2) opened up a new area of research. With a decade of extensive investigation, it is now recognized that: (1) TPH2 exhibits a highly flexible gene expression that is modulated by an increasing number of internal and external environmental factors including the biological clock, stressors, endogenous hormones, and antidepressant therapies; and (2) genetically determined TPH2 activity is linked to a growing body of stress-related neuronal correlates and behavioral traits. These findings reveal an active role of TPH2 in the stress response and provide new insights into the long recognized but not yet fully understood 5-HT-stress interaction. As a major modulator of 5-HT neurotransmission and the stress response, TPH2 is of both pathophysiological and pharmacological significance, and is emerging as a new therapeutic target for the treatment of stress disorders. Given that numerous antidepressant therapies influence TPH2 gene expression, TPH2 is already inadvertently targeted for the treatment of stress disorders. With increased understanding of the regulation of TPH2 activity we can now purposely utilize TPH2 as a target to develop new or optimize current therapies, which are expected to greatly improve the prevention and treatment of a wide variety of stress disorders.

[Effect of acupuncture intervention on learning-memory ability and cerebral superoxide dismutase activity and malonaldehyde concentration in chronic fatigue syndrome rats].

OBJECTIVE: To observe the effect of acupuncture intervention on learning-memory ability and cerebral superoxide dismutase (SOD) activity and malonaldehyde (MDA) content in chronic fatigure syndrome (CFS) rats so as to reveal its mechanism underlying improvement of clinical CFS. METHODS: Thirty-six male SD rats were randomly divided into control group, model group and acupuncture group (n = 12 in each group). CFS model was established by double stress stimulation of suspending (1.0 - 2.5 h increasing gradually) and forced swimming [Morris water maze tasks, 7 min in (10 +/- 1) degrees C water], once daily for 12 days. Manual acupuncture stimulation was applied to "Baihui" (CV 20), bilateral "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), once daily for 21 days (with 3 days' interval between every two weeks). Learning-memory ability was determined by Morris water maze tests, and SOD activity and MDA concentration in the brain tissues were detected by xanthine oxidase method and thiobarbiturif acid method, respectively. RESULTS: Compared with the control group, the escape latencies at time-points of day 1, 2, 3, 4 and 5 of Morris water maze tests were significantly longer, the target platform crossing times were markedly fewer and the target platform quadrant staying time obviously shorter, cerebral SOD activity was considerably decreased, and cerebral MDA content remarkably increased in the model group (P < 0.05, P < 0.01). Following acupuncture intervention, the escape latencies at time-points of day 1, 2, 3, 4 and 5 were significantly decreased, both target platform crossing times and staying time, and cerebral SOD activity were apparently increased, as well as cerebral MDA level was markedly lowered in comparison with the model group (P<0.05, P<0.01). CONCLUSION: Acupuncture intervention can improve the learning-memory ability in CFS rats, which may be related to its effect in regulating metabolism of free radicals in the brain tissues.

Association of monoamine-synthesizing genes with the depression tendency and personality in chronic fatigue syndrome patients.

AIMS: Tyrosine hydroxylase (TH) and GTP cyclohydrolase I (GCH) are the rate-limiting enzymes for the biosynthesis of catecholamines and tetrahydrobiopterin (BH4), respectively. Since catecholamines and BH4 are thought to be involved in the pathophysiology of CFS, we explored the genetic factors that influence CFS development and examined the possible association between the SNPs of the TH and GCH genes and the various characteristics of CFS patients. MAIN METHODS: After drawing venous blood from CFS patients and controls, genomic DNA was then extracted from whole blood in accordance with standard procedures. Digestion patterns of the PCR products were used for genotyping the SNPs of GCH (rs841; C+243T) and TH (rs10770141; C-824T). We also performed questionnaires consisting of fatigue-scale and temperament and character inventory scale (TCI) to CFS patients. KEY FINDINGS: Our results demonstrated that the allele differences for the GCH and TH SNPs were not associated with CFS patients. We did find that the GCH gene with the C+243T polymorphism affected harm avoidance, while the TH gene with the C-824T polymorphism affected persistence in the CFS patients. The concept of persistence has been linked to specific personality, such as perfectionism, in CFS. SIGNIFICANCE: Our results suggest that the biosynthetic pathways of the monoamine neurotransmitters that are mediated by TH and GCH might be associated with the CFS clinical findings, because persistence is one of the typical personality traits observed in CFS and patients with major depressive disorder exhibit a higher harm avoidance score.

[Effect of acupuncture on serum malonaldehyde content, superoxide dismutase and glutathione peroxidase activity in chronic fatigue syndrome rats].

OBJECTIVE: To study the effect of acupuncture on blood oxygen free radical metabolism in rats with chronic fatigue syndrome (CFS). METHODS: Thirty male SD rats were randomly divided into control group (n = 10), model group (n = 10) and acupuncture group (n = 10). CFS model was established by repeated suspension (1.0-2.5 h) and forced cold water swimming (7 min), once daily continuously for 12 days. For rats in the acupuncture group, bilateral "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) were stimulated by manipulating the acupuncture needles intermittently for 20 min, once daily, and with 7 days being a treatment course. The treatment was conducted for three courses with an interval of 3 days between two courses. Serum malonaldehyde (MDA) content, superoxide dismutase (SOD) activity, and glutathione peroxidase (GSH-PX) activity were detected by thiobarbituric acid chromatometry (TBA), xanthine oxidase (XOD) and dithio-bis-nitrobenzoic acid (DTNB), respectively. RESULTS: In comparison with the control group, serum MDA content was up-regulated significantly, while serum SOD activity and GSH-PX activity were decreased considerably in the model group (P < 0.01). Compared with the model group, serum MDA level was down-regulated apparently, and serum SOD activity and GSH-PX activity were up-regulated remarkably in the acupuncture group (P < 0.01). CONCLUSION: Acupuncture can adjust metabolism of serum oxygen free radicals in CFS rats, which probably contributes to its effect in relieving CFS in clinic.

Mitochondrial enzymes discriminate between mitochondrial disorders and chronic fatigue syndrome.

We studied the extent of mitochondrial involvement in chronic fatigue syndrome (CFS) and investigated whether measurement of mitochondrial respiratory chain complex (RCC) activities discriminates between CFS and mitochondrial disorders. Mitochondrial content was decreased in CFS compared to healthy controls, whereas RCC activities corrected for mitochondrial content were not. Conversely, mitochondrial content did not discriminate between CFS and two groups of mitochondrial disorders, whereas ATP production rate and complex I, III and IV activity did, all with higher activities in CFS. We conclude that the ATP production rate and RCC activities can reliably discriminate between mitochondrial disorders and CFS.

Long-chain acylcarnitine deficiency in patients with chronic fatigue syndrome. Potential involvement of altered carnitine palmitoyltransferase-I activity.

OBJECTIVE: The underlying aetiology of chronic fatigue syndrome is currently unknown; however, in the light of carnitine's critical role in mitochondrial energy production, it has been suggested that chronic fatigue syndrome may be associated with altered carnitine homeostasis. This study was conducted to comparatively examine full endogenous carnitine profiles in patients with chronic fatigue syndrome and healthy controls. DESIGN: A cross-sectional, observational study. SETTING AND SUBJECTS: Forty-four patients with chronic fatigue syndrome and 49 age- and gender-matched healthy controls were recruited from the community and studied at the School of Pharmacy & Medical Sciences, University of South Australia. MAIN OUTCOME MEASURES: All participants completed a fatigue severity scale questionnaire and had a single fasting blood sample collected which was analysed for l-carnitine and 35 individual acylcarnitine concentrations in plasma by LC-MS/MS. RESULTS: Patients with chronic fatigue syndrome exhibited significantly altered concentrations of C8:1, C12DC, C14, C16:1, C18, C18:1, C18:2 and C18:1-OH acylcarnitines; of particular note, oleyl-L-carnitine (C18:1) and linoleyl-L-carnitine (C18:2) were, on average, 30-40% lower in patients than controls (P < 0.0001). Significant correlations between acylcarnitine concentrations and clinical symptomology were also demonstrated. CONCLUSIONS: It is proposed that this disturbance in carnitine homeostasis is reflective of a reduction in carnitine palmitoyltransferase-I (CPT-I) activity, possibly a result of the accumulation of omega-6 fatty acids previously observed in this patient population. It is hypothesized that the administration of omega-3 fatty acids in combination with l-carnitine would increase CPT-I activity and improve chronic fatigue syndrome symptomology.

Biomarkers in chronic fatigue syndrome: evaluation of natural killer cell function and dipeptidyl peptidase IV/CD26.

BACKGROUND: Chronic Fatigue Syndrome (CFS) studies from our laboratory and others described decreased natural killer cell cytotoxicity (NKCC) and elevated proportion of lymphocytes expressing the activation marker, dipeptidyl peptidase IV (DPPIV) also known as CD26. However, neither these assays nor other laboratory tests are widely accepted for the diagnosis or prognosis of CFS. This study sought to determine if NKCC or DPPIV/CD26 have diagnostic accuracy for CFS. METHODS/RESULTS: Subjects included female and male CFS cases and healthy controls. NK cell function was measured with a bioassay, using K562 cells and (51)Cr release. Lymphocyte associated DPPIV/CD26 was assayed by qualitative and quantitative flow cytometry. Serum DPPIV/CD26 was measured by ELISA. Analysis by receiver operating characteristic (ROC) curve assessed biomarker potential. Cytotoxic function of NK cells for 176 CFS subjects was significantly lower than in the 230 controls. According to ROC analysis, NKCC was a good predictor of CFS status. There was no significant difference in NK cell counts between cases and controls. Percent CD2+ lymphocytes (T cells and NK cells) positive for DPPIV/C26 was elevated in CFS cases, but there was a decrease in the number of molecules (rMol) of DPPIV/C26 expressed on T cells and NK cells and a decrease in the soluble form of the enzyme in serum. Analyses by ROC curves indicated that all three measurements of DPPIV/CD26 demonstrated potential as biomarkers for CFS. None of the DPPIV/C26 assays were significantly correlated with NKCC. CONCLUSIONS: By ROC analysis, NKCC and three methods of measuring DPPIV/C26 examined in this study had potential as biomarkers for CFS. Of these, NKCC, %CD2+CD26+ lymphocytes and rMol CD26/CD2+ lymphocyte, required flow cytometry, fresh blood and access to a high complexity laboratory. Soluble DPPIV/C26 in serum is done with a standard ELISA assay, or with other soluble factors in a multiplex type of ELISA. Dipeptidyl peptidase IV on lymphocytes or in serum was not predictive of NKCC suggesting that these should be considered as non-redundant biomarkers. Abnormalities in DPPIV/CD26 and in NK cell function have particular relevance to the possible role of infection in the initiation and/or the persistence of CFS.

[Effect of Tuina on oxygen free radicals metabolism in patients with chronic fatigue syndrome].

OBJECTIVE: To explore the mechanism of Tuina for treatment of chronic fatigue syndrome. METHODS: A total of 90 patients were randomly divided into a Tuina group, a Taijiquan (take exercise) group and a Fluoxetine group, 30 cases in each group. They were treated with Tuina, Taijiquan and Fluoxetine, respectively. After a month, the therapeutic effects and the changes of malondialdehyde (MDA) content and the activity of serum superoxide dismutases (SOD) and serum glutathione peroxidase (GSH-Px) were ohserved. RESULTS: The total effective rate of 93.3% (28/30) in the Tuina group was better than 80.0% (24/30) in the Taijiquan group and 73.3% (22/30) in the Fluoxetine group (both P < 0.05). After treatment, MDA contents in the three groups were all decreased (P < 0.01, P < 0.05), and the activity of SOD. GSH-Px in both the Tuina group and the Fluoxetine group were increased (P < 0.01, P < 0.05), and especially in the Tuina group with a significant difference as compared with the other two groups (P < 0.05, P < 0.01). CONCLUSION: The therapeutic effect of the Tuina group is superior to that of the Taijiquan group and the Fluoxetine group. Tuina can regulate oxygen free radicals metabolism and clean superfluous oxygen free radicals to alleviate fatigue, which may be one of the mechanisms of Tuina in treating chronic fatigue syndrome.

Unravelling intracellular immune dysfunctions in chronic fatigue syndrome: interactions between protein kinase R activity, RNase L cleavage and elastase activity, and their clinical relevance.

This study examined possible interactions between immunological abnormalities and symptoms in CFS. Sixteen CFS patients filled in a battery of questionnaires, evaluating daily functioning, and underwent venous blood sampling, in order to analyse immunological abnormalities. Ribonuclease (RNase) L cleavage was associated with RNase L activity (rs=0.570; p=0.021), protein kinase R (PKR) (rs=0.716; p=0.002) and elastase activity (rs=0.500; p=0.049). RNase L activity was related to elastase (rs=0.547; p=0.028) and PKR activity (rs=0.625; p=0.010). RNase L activity (rs=0.535; p=0.033), elastase activity (rs=0.585; p=0.017) and RNase L cleavage (rs=0.521; p=0.038) correlated with daily functioning. This study suggests that in CFS patients an increase in elastase activity and subsequent RNase L cleavage is accompanied by increased activity of both the PKR and RNase L enzymes. RNase L and elastase activity are related to daily functioning, thus evidence supporting the clinical importance of these immune dysfunctions in CFS patients was provided.

Intracellular immune dysfunction in myalgic encephalomyelitis/chronic fatigue syndrome: state of the art and therapeutic implications.

BACKGROUND: Evidence in support of intracellular immune dysfunctions in people with myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) is accumulating, but few studies have addressed intracellular immunity as a potential therapeutic target. OBJECTIVE: To provide an overview of our present understanding of intracellular immunity in ME/CFS, to relate the intracellular immune dysfunctions to other aspects of the illness like decreased natural killer cell function, the presence of infections and poor exercise performance, and to point to potential therapeutic targets. METHODS: An in-depth review of the scientific literature of intracellular immunity in people with ME/CFS was performed. RESULTS/CONCLUSION: From the scientific literature it is concluded that proteolytic cleavage of the native RNase L enzyme is characteristic of the dysregulation of intracellular immunity in people with ME/CFS, but the origin of the dysregulation is speculative. There is increasing evidence for immune cell apoptosis and upregulation of various aspects of the 2'-5' oligoadenylate (2-5A) synthetase/RNase L pathway in ME/CFS. This review provides the theoretical rationale for conducting studies examining the effectiveness of direct or indirect drug targeting of the 2-5A synthetase/RNase L pathway in ME/CFS patients.

Not in the mind but in the cell: increased production of cyclo-oxygenase-2 and inducible NO synthase in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a medically unexplained disorder, characterized by profound fatigue, infectious, rheumatological and neuropsychiatric symptoms. There is, however, some evidence that CFS is accompanied by signs of increased oxidative stress and inflammation in the peripheral blood. This paper examines the role of the inducible enzymes cyclo-oxygenase (COX-2) and inducible NO synthase (iNOS) in the pathophysiology of CFS. Toward this end we examined the production of COX-2 and iNOS by peripheral blood lymphocytes (PBMC) in 18 CFS patients and 18 normal volunteers and examined the relationships between those inflammatory markers and the severity of illness as measured by means of the FibroFatigue scale and the production of the transcription factor nuclear factor kappa beta (NFkappabeta). We found that the production of COX-2 and iNOS was significantly higher in CFS patients than in normal controls. There were significant and positive intercorrelations between COX-2, iNOS and NFkappabeta and between COX-2 and iNOS, on the one hand, and the severity of illness, on the other. The production of COX-2 and iNOS by PBMCs was significantly related to aches and pain, muscular tension, fatigue, concentration difficulties, failing memory, sadness and a subjective experience of infection. The results suggest that a) an intracellular inflammatory response in the white blood cells plays an important role in the pathophysiology of CFS; b) the inflammatory response in CFS is driven by the transcription factor NFkappabeta; c) symptoms, such as fatigue, pain, cognitive defects and the subjective feeling of infection, indicates the presence of a genuine inflammatory response in CFS patients; and d) CFS patients may be treated with substances that inhibit the production of COX-2 and iNOS.

[Gamma-aminobutyric acid--metabolism and its disorders]. / Kwas gamma-aminomaslowy--metabolizm i jego zaburzenia.

Gamma-aminobutyric acid is a major inhibitory neurotransmitter in the central nervous system. GABA metabolism is dependent on the activity of three enzymes: glutamic acid decarboxylase, GABA-transaminase and succinic semialdehyde dehydrogenase. Decreased activity of these enzymes may cause many neurological syndromes, such as stiff-person syndrome, chronic fatigue syndrome, anxiety disorders and seizures. This article is a review of most important problems related to an impairment of GABA metabolism.

Impairments of the 2-5A synthetase/RNase L pathway in chronic fatigue syndrome.

This paper provides an overview of the evidence addressing the impairments of the 2'-5' oligoadenylate (2-5 A) synthetase/RNase L pathway in Chronic Fatigue Syndrome (CFS) patients. The 2-5A synthetase/RNase L pathway in CFS patients appears to be both up-regulated (i.e. increased levels of bioactive 2-5A synthetase and increased activity of the RNase L enzyme) and deregulated (elastase and calpain initiate 83 kDa RNase L proteolysis, generating two major fragments with molecular masses of 37 and 30 kDa, respectively). The deregulation of the 2-5A synthetase/RNase L pathway in CFS accompanies decreased NK-function and deregulation of apoptotic pathways. Since various components of the pathway appear to be related to performance during a graded exercise stress test, some evidence supportive of the clinical importance of the impaired pathway in CFS patients has been provided. Studies addressing the treatment of the deregulation of the 2-5A synthetase/RNase L pathway in CFS are warranted.

Chronic fatigue syndrome: exercise performance related to immune dysfunction.

PURPOSE: To date, the exact cause of abnormal exercise response in chronic fatigue syndrome (CFS) remains to be revealed, but evidence addressing intracellular immune deregulation in CFS is growing. Therefore, the aim of this cross-sectional study was to examine the interactions between several intracellular immune variables and exercise performance in CFS patients. METHODS: After venous blood sampling, subjects (16 CFS patients) performed a maximal exercise stress test on a bicycle ergometer with continuous monitoring of cardiorespiratory variables. The following immune variables were assessed: the ratio of 37 kDa Ribonuclease (RNase) L to the 83 kDa native RNase L (using a radiolabeled ligand/receptor assay), RNase L enzymatic activity (enzymatic assay), protein kinase R activity assay (comparison Western blot), elastase activity (enzymatic-colorimetric assay), the percent of monocytes, and nitric oxide determination (for monocytes and lymphocytes; flow cytometry, live cell assay). RESULTS: Forward stepwise multiple regression analysis revealed 1) that elastase activity was the only factor related to the reduction in oxygen uptake at a respiratory exchange ratio (RER) of 1.0 (regression model: R = 0.53, F (1,14) = 15.5, P < 0.002; elastase activity P < 0.002); 2) that the protein kinase R activity was the principle factor related to the reduction in workload at RER = 1.0; and 3) that elastase activity was the principle factor related to the reduction in percent of target heart rate achieved. CONCLUSION: These data provide evidence for an association between intracellular immune deregulation and exercise performance in patients with CFS. To establish a causal relationship, further study of these interactions using a prospective longitudinal design is required.

Ribonuclease L proteolysis in peripheral blood mononuclear cells of chronic fatigue syndrome patients.

A 37-kDa binding polypeptide accumulates in peripheral blood mononuclear cell (PBMC) extracts from chronic fatigue syndrome (CFS) patients and is being considered as a potential diagnostic marker (De Meirleir, K., Bisbal, C., Campine, I., De Becker, P., Salehzada, T., Demettre, E., and Lebleu, B. (2000) Am. J. Med. 108, 99-105). We establish here that this low molecular weight 2-5A-binding polypeptide is a truncated form of the native 2-5A-dependent ribonuclease L (RNase L), generated by an increased proteolytic activity in CFS PBMC extracts. RNase L proteolysis in CFS PBMC extracts can be mimicked in a model system in which recombinant RNase L is treated with human leukocyte elastase. RNase L proteolysis leads to the accumulation of two major fragments with molecular masses of 37 and 30 kDa. The 37-kDa fragment includes the 2-5A binding site and the N-terminal end of native RNase L. The 30-kDa fragment includes the catalytic site in the C-terminal part of RNase L. Interestingly, RNase L remains active and 2-5A-dependent when degraded into its 30- and 37-kDa fragments by proteases of CFS PBMC extract or by purified human leukocyte elastase. The 2-5A-dependent nuclease activity of the truncated RNase L could result from the association of these digestion products, as suggested in pull down experiments.