It is not well understood why some patients develop a subjective syndrome that includes considerable fatigue, musculoskeletal aches, and neurocognitive dysfunction after receiving standard antibiotic courses for the treatment of Lyme disease. Some practitioners use the term "chronic Lyme disease" and order prolonged courses of oral and parenteral antibiotics, believing that persistent infection with Borrelia burgdorferi is responsible. However, well-performed prospective studies have found neither evidence of chronic infection nor a benefit worthy of long-term antibiotic therapy for these patients. Such extended antibiotic therapy poses hazards and cannot be viewed as acceptable. The term "chronic Lyme disease" should be discarded as misleading; rather, the term "post-Lyme disease syndrome" better reflects the postinfectious nature of this condition. Further research is necessary to understand possible mechanisms of these chronic symptoms following Lyme disease as well as to find effective therapies.

Background. Infectious mononucleosis (IM) commonly triggers a protracted postinfective fatigue syndrome (PIFS) of unknown pathogenesis.Methods. Seven subjects with PIFS with 6 or more months of disabling symptoms and 8 matched control subjects who had recovered promptly from documented IM were studied. The expression of 30,000 genes was examined in the peripheral blood by microarray analysis in 65 longitudinally collected samples. Gene expression patterns associated with PIFS were sought by correlation with symptom factor scores.Results. Differential expression of 733 genes was identified when samples collected early during the illness and at the late (recovered) time point were compared. Of these genes, 234 were found to be significantly correlated with the reported severity of the fatigue symptom factor, and 180 were found to be correlated with the musculoskeletal pain symptom factor. Validation by analysis of the longitudinal expression pattern revealed 35 genes for which changes in expression were consistent with the illness course. These genes included several that are involved in signal transduction pathways, metal ion binding, and ion channel activity.Conclusions. Gene expression correlates of the cardinal symptoms of PIFS after IM have been identified. Further studies of these gene products may help to elucidate the pathogenesis of PIFS.

Symptomatic primary Epstein-Barr virus infection is known more commonly as infectious mononucleosis, an illness known for afflicting adolescents and younger adults as a febrile illness accompanied by pharyngitis and lymphadenopathy. Historically believed to be generally benign, infectious mononucleosis has been linked more recently to increased risks of developing Hodgkin's lymphoma and multiple sclerosis. Advances in the understanding of host immune responses to Epstein-Barr virus have begun to elucidate the reasons why younger children typically experience subclinical infection whereas older individuals develop infectious mononucleosis. This review will highlight recent advances in the understanding of primary Epstein-Barr virus infection, and whether prospective treatments or vaccine strategies may affect native infection and its sequelae.

Objective: To identify biomarkers of chronic fatigue syndrome (CFS) and related disorders through analysis of microarray data, pathology test results and self-report symptom profiles. Method: To empirically derive the symptom domains of the illnesses, factor analysis was performed on responses to self-report questionnaires (multidimensional fatigue inventory, Centers for Disease Control and Prevention (CDC) symptom inventory and Zung depression scale) before validation with independent datasets. Gene expression patterns that distinguished subjects across each factor dimension were then sought. Results: A four-factor solution was favored, featuring 'fatigue' and 'mood disturbance' factors. Scores on these factors correlated with measures of disability on the Short Form (SF)-36. A total of 57 genes that distinguished subjects along each factor dimension were identified, although the separation was significant only for subjects beyond the extreme (15(th) and 85(th)) percentiles of severity. Clustering of laboratory parameters with expression of these genes revealed associations with serum measurements of pH, electrolytes, glucose, urea, creatinine, and liver enzymes (aspartate amino transferase [AST] and alanine amino transferase [AST]); as well as hematocrit and white cell count. Conclusion: CFS is a complex syndrome that cannot simply be associated with changes in individual laboratory tests or expression levels of individual genes. No clear association with gene expression and individual symptom domains was found. However, analysis of such multifacetted datasets is likely to be an important means to elucidate the pathogenesis of CFS.

OBJECTIVE: To delineate the risk factors, symptom patterns, and longitudinal course of prolonged illnesses after a variety of acute infections. DESIGN: Prospective cohort study following patients from the time of acute infection with Epstein-Barr virus (glandular fever), Coxiella burnetii (Q fever), or Ross River virus (epidemic polyarthritis). SETTING: The region surrounding the township of Dubbo in rural Australia, encompassing a 200 km geographical radius and 104 400 residents. PARTICIPANTS: 253 patients enrolled and followed at regular intervals over 12 months by self report, structured interview, and clinical assessment. OUTCOME MEASURES: Detailed medical, psychiatric, and laboratory evaluations at six months to apply diagnostic criteria for chronic fatigue syndrome. Premorbid and intercurrent illness characteristics recorded to define risk factors for chronic fatigue syndrome. Self reported illness phenotypes compared between infective groups. RESULTS: Prolonged illness characterised by disabling fatigue, musculoskeletal pain, neurocognitive difficulties, and mood disturbance was evident in 29 (12%) of 253 participants at six months, of whom 28 (11%) met the diagnostic criteria for chronic fatigue syndrome. This post-infective fatigue syndrome phenotype was stereotyped and occurred at a similar incidence after each infection. The syndrome was predicted largely by the severity of the acute illness rather than by demographic, psychological, or microbiological factors. CONCLUSIONS: A relatively uniform post-infective fatigue syndrome persists in a significant minority of patients for six months or more after clinical infection with several different viral and non-viral micro-organisms. Post-infective fatigue syndrome is a valid illness model for investigating one pathophysiological pathway to chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is prevalent, disabling and costly. Despite extensive literature describing the epidemiology and clinical aspects of CFS, it has been recalcitrant to diagnostic biomarker discovery and therapeutic intervention. This is due to the fact that CFS is a complex illness defined by self-reported symptoms and diagnosed by the exclusion of medical and psychiatric diseases that may explain the symptoms. Studies attempting to dissect the pathophysiology are challenging to design as CFS affects multiple body systems, making the choice of which system to study dependant on an investigators area of expertise. However, the peripheral blood appears to be facilitating the molecular profiling of several diseases, such as CFS, that involve bodywide perturbations that are mediated by the CNS. Successful molecular profiling of CFS will require the integration of genetic, genomic and proteomic data with environmental and behavioral data to define the heterogeneity in order to optimize intervention.

ABSTRACT: BACKGROUND: Acute infectious diseases are typically accompanied by non-specific symptoms including fever, malaise, irritability and somnolence that usually resolve on recovery. However, in some individuals these symptoms persist in what is commonly termed post-infective fatigue. The objective of this pilot study was to determine the gene expression correlates of post-infective fatigue following acute Epstein Barr virus (EBV) infection. METHODS: We followed 5 people with acute mononucleosis who developed post-infective fatigue of more than 6 months duration and 5 HLA-matched control subjects who recovered within 3 months. Subjects had peripheral blood mononuclear cell (PBMC) samples collected at varying time points including at diagnosis, then every 2 weeks for 3 months, then every 3 months for a year. Total RNA was extracted from the PBMC samples and hybridized to microarrays spotted with 3,800 oligonucleotides. RESULTS: Those who developed post-infective fatigue had gene expression profiles indicative of an altered host response during acute mononucleosis compared to those who recovered uneventfully. Several genes including ISG20 (interferon stimulated gene), DNAJB2 (DnaJ [Hsp40] homolog and CD99), CDK8 (cyclin-dependent kinase 8), E2F2 (E2F transcription factor 2), CDK8 (cyclin-dependent kinase 8), and ACTN2 (actinin, alpha 2), known to be regulated during EBV infection, were differentially expressed in post-infective fatigue cases. Several of the differentially expressed genes affect mitochondrial functions including fatty acid metabolism and the cell cycle. CONCLUSIONS: These preliminary data provide insights into alterations in gene transcripts associated with the varied clinical outcomes from acute infectious mononucleosis.

We investigated peripheral blood mononuclear cell gene expression responses to acute psychosocial stress to identify molecular pathways relevant to the stress response. Blood samples were obtained from ten healthy male subjects before, during and after (at 0, 30, and 60minutes) a standardized psychosocial laboratory stressor. Ribonucleic acid (RNA) was extracted and gene expression measured by hybridization to a 20,000-gene microarray. Gene Set Expression Comparisons (GSEC) using defined pathways were used for the analysis. Forty-nine pathways were significantly changed from baseline to immediately after the stressor (p < 0.05), implicating cell cycle, cell signaling, adhesion and immune responses. The comparison between stress and recovery (measured 30minutes later) identified 36 pathways, several involving stress-responsive signaling cascades and cellular defense mechanisms. These results have relevance for understanding molecular mechanisms of the physiological stress response, and might be used to further study adverse health outcomes of psychosocial stress.

ABSTRACT: BACKGROUND: Gulf War Illness (GWI) remains a serious health consequence for at least 11,000 veterans of the first Gulf War in the early 1990s. Our understanding of the health consequences that resulted remains inadequate, and this is of great concern with another deployment to the same theater of operations occurring now. Chronic immune cell dysfunction and activation have been demonstrated in patients with GWI, although the literature is not uniform. We exposed GWI patients and matched controls to an exercise challenge to explore differences in immune cell function measured by classic immune assays and gene expression profiling. METHODS: This pilot study enrolled 9 GWI cases identified from the Department of Veterans Affairs GWI registry, and 11 sedentary control veterans who had not been deployed to the Persian Gulf and were matched to cases by sex, body mass index (BMI) and age. We measured peripheral blood cell numbers, NK cytotoxicity, cytokines and expression levels of 20,000 genes immediately before, immediately after and 4 hours following a standard bicycle ergometer exercise challenge. RESULTS: A repeated-measures analysis of variance revealed statistically significant differences for three NK cell subsets and NK cytotoxicity between cases and controls (p < 0.05). Linear regression analysis correlating NK cell numbers to the gene expression profiles showed high correlation of genes associated with NK cell function, serving as a biologic validation of both the in vitro assays and the microarray platform. Intracellular perforin levels in NK and CD8 T-cells trended lower and showed a flatter profile in GWI cases than controls, as did the expression levels of the perforin gene PRF1. Genes distinguishing cases from controls were associated with the glucocorticoid signaling pathway. CONCLUSION: GWI patients demonstrated impaired immune function as demonstrated by decreased NK cytotoxicity and altered gene expression associated with NK cell function. Pro-inflammatory cytokines, T-cell ratios, and dysregulated mediators of the stress response (including salivary cortisol) were also altered in GWI cases compared to control subjects. An interesting and potentially important observation was that the exercise challenge augments these differences, with the most significant effects observed immediately after the stressor, possibly implicating some block in the NK and CD8 T-cells ability to respond to "stress-mediated activation". This has positive implications for the development of laboratory diagnostic tests for this syndrome and provides a paradigm for exploration of the immuno-physiological mechanisms that are operating in GWI, and similar complex syndromes. Our results do not necessarily elucidate the cause of GWI, but they do reveal a role for immune cell dysfunction in sustaining illness.

OBJECTIVE: The validity of the diagnosis of chronic fatigue syndrome and related chronic fatigue states remains controversial, particularly in psychiatry. This project utilized international epidemiological and clinical research data to test construct validity across diagnostic categories, health-care settings and countries. Relevant demographic, symptom and diagnostic data were obtained from 33 studies in 21 countries. The subjects had fatigue lasting 1-6 months (prolonged fatigue), or >6 months (chronic fatigue), or met diagnostic criteria for chronic fatigue syndrome. METHOD: Common symptom domains were derived by factor analytic techniques. Mean scores on each symptom factor were compared across diagnostic categories, health-care settings and countries. RESULTS: Data were obtained on 37,724 subjects (n = 20,845 female, 57%), including from population-based studies (n = 15,749, 42%), studies in primary care (n = 19 472, 52%), and secondary or specialist tertiary referral clinics (n = 2503, 7%). The sample included 2013 subjects with chronic fatigue, and 1958 with chronic fatigue syndrome. A five-factor model of the key symptom domains was preferred ('musculoskeletal pain/fatigue','neurocognitive difficulties','inflammation','sleep disturbance/fatigue' and 'mood disturbance') and was comparable across subject groups and settings. Although the core symptom profiles were similar, some differences in symptoms were observed across diagnostic categories, health-care settings and between countries. CONCLUSIONS: The construct validity of chronic fatigue and chronic fatigue syndrome is supported by an empirically derived factor structure from existing international datasets.

ABSTRACT: BACKGROUND: Systems biologic approaches such as Weighted Gene Co-expression Network Analysis (WGCNA) can effectively integrate gene expression and trait data to identify pathways and candidate biomarkers. Here we show that the additional inclusion of genetic marker data allows one to characterize network relationships as causal or reactive in a chronic fatigue syndrome (CFS) data set. RESULTS: We combine WGCNA with genetic marker data to identify a disease-related pathway and its causal drivers, an analysis which we refer to as "Integrated WGCNA" or IWGCNA. Specifically, we present the following IWGCNA approach: 1) construct a co-expression network, 2) identify trait-related modules within the network, 3) use a trait-related genetic marker to prioritize genes within the module, 4) apply an integrated gene screening strategy to identify candidate genes and 5) carry out causality testing to verify and/or prioritize results. By applying this strategy to a CFS data set consisting of microarray, SNP and clinical trait data, we identify a module of 299 highly correlated genes that is associated with CFS severity. Our integrated gene screening strategy results in 20 candidate genes. We show that our approach yields biologically interesting genes that function in the same pathway and are causal drivers for their parent module. We use a separate data set to replicate findings and use Ingenuity Pathways Analysis software to functionally annotate the candidate gene pathways. CONCLUSIONS: We show how WGCNA can be combined with genetic marker data to identify disease-related pathways and the causal drivers within them. The systems genetics approach described here can easily be used to generate testable genetic hypotheses in other complex disease studies.

Microarrays are a powerful laboratory tool for the simultaneous assessment of the activity of thousands genes. Remarkable advances in biological sample collection, preparation and automation of hybridization have enabled the application of microarray technology to large, population-based studies. Now, microarrays have the potential to serve as screening tools for the detection of altered gene expression activity that might contribute to diseases in human populations. Reproducible and reliable microarray results depend on multiple factors. In this chapter, biological sample parameters are introduced that should be considered for any microarray experiment. Then, the microarray technology that we have successfully applied to limited biological sample from all our molecular epidemiology studies is detailed. This reproducible and reliable approach for using microarrays should be applicable to any biological questions asked.

Chronic fatigue syndrome (CFS) is a debilitating disorder of unknown etiology with no known lesions, diagnostic markers or therapeutic intervention. The pathophysiology of CFS remains elusive, although abnormalities in the central nervous system (CNS) have been implicated, particularly hyperactivity of the serotonergic (5-hydroxytryptamine; 5-HT) system and hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Since alterations in 5-HT signaling can lead to physiologic and behavioral changes, a genetic evaluation of the 5-HT system was undertaken to identify serotonergic markers associated with CFS and potential mechanisms for CNS abnormality. A total of 77 polymorphisms in genes related to serotonin synthesis (TPH2), signaling (HTR1A, HTR1E, HTR2A, HTR2B, HTR2C, HTR3A, HTR3B, HTR4, HTR5A, HTR6, and HTR7), transport (SLC6A4), and catabolism (MAOA) were examined in 137 clinically evaluated subjects (40 CFS, 55 with insufficient fatigue, and 42 non-fatigued, NF, controls) derived from a population-based CFS surveillance study in Wichita, Kansas. Of the polymorphisms examined, three markers (-1438G/A, C102T, and rs1923884) all located in the 5-HT receptor subtype HTR2A were associated with CFS when compared to NF controls. Additionally, consistent associations were observed between HTR2A variants and quantitative measures of disability and fatigue in all subjects. The most compelling of these associations was with the A allele of -1438G/A (rs6311) which is suggested to have increased promoter activity in functional studies. Further, in silico analysis revealed that the -1438 A allele creates a consensus binding site for Th1/E47, a transcription factor implicated in the development of the nervous system. Electrophoretic mobility shift assay supports allele-specific binding of E47 to the A allele but not the G allele at this locus. These data indicate that sequence variation in HTR2A, potentially resulting in its enhanced activity, may be involved in the pathophysiology of CFS.

BACKGROUND:: A consequence of a number of diseases is an alteration in apoptosis. Currently, there is no single assay that measures the main stages of apoptosis, requiring that multiple assays be performed. This hinders studies on clinical samples that have limited cell numbers. Our objective was to combine and optimize assays that target specific stages of apoptosis for use in a typical clinical blood sample. METHODS:: Two flow cytometric assays were developed for use on peripheral blood mononuclear cells (PBMC) collected in two 8-ml tubes from a single draw. One measures caspase-12 activity, the level of active caspase-3 and DNA fragmentation. The second assesses depolarization of the mitochondria and phosphatidylserine externalization. Cell populations present within the samples were determined by flow cytometry. Apoptosis was validated by ELISA. RESULTS:: Each assay was optimized for use with cell numbers and sample volumes typical of clinical blood samples. Each combination assay effectively distinguished apoptotic from nonapoptotic blood cells. CONCLUSIONS:: This combined optimized method comprised of two independent assays makes it possible to assay the major pathways of apoptosis in addition to determining the blood cell subsets that are affected. Published 2007 Wiley-Liss, Inc.

Background. Infectious mononucleosis (IM) commonly triggers a protracted postinfective fatigue syndrome (PIFS) of unknown pathogenesis.Methods. Seven subjects with PIFS with 6 or more months of disabling symptoms and 8 matched control subjects who had recovered promptly from documented IM were studied. The expression of 30,000 genes was examined in the peripheral blood by microarray analysis in 65 longitudinally collected samples. Gene expression patterns associated with PIFS were sought by correlation with symptom factor scores.Results. Differential expression of 733 genes was identified when samples collected early during the illness and at the late (recovered) time point were compared. Of these genes, 234 were found to be significantly correlated with the reported severity of the fatigue symptom factor, and 180 were found to be correlated with the musculoskeletal pain symptom factor. Validation by analysis of the longitudinal expression pattern revealed 35 genes for which changes in expression were consistent with the illness course. These genes included several that are involved in signal transduction pathways, metal ion binding, and ion channel activity.Conclusions. Gene expression correlates of the cardinal symptoms of PIFS after IM have been identified. Further studies of these gene products may help to elucidate the pathogenesis of PIFS.

For the past two decades, research appearing in the pages of Brain, Behavior, and Immunity (BBI), as well as other journals, has significantly deepened our understanding of the complexities of endocrine regulation of immunity in states of health and disease. This mini-review discusses contributions that endocrinology has made to the field of psycho-neuroimmunology (PNI), as well as discoveries that PNI researchers have made of the pervasive interactions between the endocrine and immune systems. We highlight the endocrine-immune interface, emphasizing similarities between the immune and endocrine systems as well as hormone/cytokine interactions. Differing endocrine-immune responses to acute and chronic psychosocial stress have been clarified during this time frame with the use of novel stress and endocrine sampling paradigms. Furthermore, investigations examining the role of cytokine involvement in acquired glucocorticoid resistance in illnesses like depression have expanded our understanding of the complexity of the endocrine-immune response to psychosocial stress. We have selected literature, with a focus on human studies, to illustrate these principals. We conclude with a discussion of the clinical relevance of endocrine-immune investigations and thoughts about the next decade of endocrine research in PNI.

ABSTRACT: BACKGROUND: Acute infectious diseases are typically accompanied by non-specific symptoms including fever, malaise, irritability and somnolence that usually resolve on recovery. However, in some individuals these symptoms persist in what is commonly termed post-infective fatigue. The objective of this pilot study was to determine the gene expression correlates of post-infective fatigue following acute Epstein Barr virus (EBV) infection. METHODS: We followed 5 people with acute mononucleosis who developed post-infective fatigue of more than 6 months duration and 5 HLA-matched control subjects who recovered within 3 months. Subjects had peripheral blood mononuclear cell (PBMC) samples collected at varying time points including at diagnosis, then every 2 weeks for 3 months, then every 3 months for a year. Total RNA was extracted from the PBMC samples and hybridized to microarrays spotted with 3,800 oligonucleotides. RESULTS: Those who developed post-infective fatigue had gene expression profiles indicative of an altered host response during acute mononucleosis compared to those who recovered uneventfully. Several genes including ISG20 (interferon stimulated gene), DNAJB2 (DnaJ [Hsp40] homolog and CD99), CDK8 (cyclin-dependent kinase 8), E2F2 (E2F transcription factor 2), CDK8 (cyclin-dependent kinase 8), and ACTN2 (actinin, alpha 2), known to be regulated during EBV infection, were differentially expressed in post-infective fatigue cases. Several of the differentially expressed genes affect mitochondrial functions including fatty acid metabolism and the cell cycle. CONCLUSIONS: These preliminary data provide insights into alterations in gene transcripts associated with the varied clinical outcomes from acute infectious mononucleosis.

Acute infection is known to perturb psycho-neuroendocrine-immune (PNI) gene expression. Oligonucleotide microarrays were used to examine PNI gene expression in the peripheral blood of 13 subjects with infectious mononucleosis (IM). Novel peripheral blood gene expression activity was correlated with central-nervous-system-mediated symptoms including fatigue and sleep disturbance. Of note, expression of the MADS box transcription enhancer factor 2 polypeptide C (MEF2C) gene, previously implicated in skeletal muscle myogenesis, correlated with symptoms of musculo-skeletal pain and fatigue. Expression of the hypocretin/orexin receptor HCRTR2, which has been implicated in narcolepsy, correlated with sleep disturbance. And, VACHT, the vesicular acetylcholine transporter, was highly correlated with neurocognitive disturbance. The expression of both HCRTR2 and MEF2C in the peripheral blood was validated by reverse transcription PCR. Thus, investigation of the PNI response in peripheral blood may provide novel insights into the complex pathophysiology of centrally mediated disease states.

Since their discovery in 1998, the hypocretins (orexins)-peptides that are produced by a group of neurons situated in the posterolateral hypothalamus--have been shown to excite many CNS areas including many neuronal systems that regulate sleep and wakefulness. Animal studies indicate that hypocretins play a part in the regulation of various functions including arousal, muscle tone, locomotion, regulation of feeding behaviour, and neuroendocrine and autonomic functions. A link between hypocretin deficiency and narcoleptic symptoms was first shown in canine and rodent models of narcolepsy. Hypocretin deficiency, as shown by low or absent concentrations in CSF, was subsequently found in 90% of patients with sporadic narcolepsy-cataplexy, and less commonly in familial narcolepsy. In most other sleep-wake and neurological disorders, hypocretin concentrations are normal. Low concentrations were also found in hypothalamic disorders, acute traumatic brain injury, and a few other disorders. The exact function of the hypocretin system in sleep-wake regulation and its pathophysiological role in hypocretin-deficient and non-deficient narcolepsy as well as in non-narcoleptic, hypocretin-deficiency syndromes remain unclear.

Imputability of thymic disorders caused by IFNalpha during the chronic Hepatitis C treatment -- hepatitis C and depression -- the infection by the hepatitis C virus (HCV) is a major public health concern since it affects 1.2% in the French population. Eighty percent of those contaminated by HCV keep bearing the virus chronically although they remain asymptomatic during many years. HCV infection is associated with psychiatric symptoms like depression. Together with other factors (eg the severity of hepatic condition), depression may induce significant impairment in quality of life. Conversely, some psychiatric conditions may increase the risk of HCV infection. In drug-addicted subjects using intravenous route, HCV contamination rate ranges from 74 to 100%. Compared with general population, a higher HCV contamination rate has also been noticed in some other subgroups of subjects (patients with alcohol abuse or dependence, with alcohol-induced hepatic disease and psychiatric inpatients). However, no valid explanation to this phenomenon has been established. Interferon alpha and depression - Interferons are a variety of cytokines naturally produced by human tissues and have also been synthesized for therapeutic purposes (treatment of a variety of cancers and viral infections). Many psychobehavioural symptoms are observed under IFNalpha treatment. Among them, mood disorders are known to occur early after entry into treatment and to be within the reach of preventive measures. The reported frequency of depression during IFNalpha treatment ranges from 0 to 37%. This variation reflects either methodological biases (eg differences in psychiatric assessment) or the heterogeneity of the population of patients accepted in therapeutic protocols. Note that the adjunction of ribavirine to IFNalpha in therapeutic protocols has not brought any changes in the depression frequency. The causal relationship between IFNalpha administration and the occurrence of mood disorders has been tackled by various recent research works focusing on the importance of the immune system in the pathophysiology of depression. Miscellaneous pathophysiological hypotheses -- nature of the psychobehavioural symptomatology -- in addition to depressive symptoms, IFNalpha treatment also induces various cognitive impairments and disruptions in EEG patterns. These symptoms are consistent with a mild subcortical dementia. Data resulting from pharmacological trials in humans and in animals are controversial (eg IFNalpha-induced symptoms being alleviated by both immune and antidepressant therapies). However, the debate about the nature of the psychobehavioural disorders observed under IFNalpha treatment might be no longer relevant in the light of recent theories which regard depression as a maladaptive response to a particular form of stress, namely a deep and diffuse feeling of sickness ("malaise"). These theoretical views ascribe the production of depressive symptoms to a disruption in the immune function, mediated by the variety of cytokines. The therapeutic effects of anti-depressive drugs are thus attributed to their analgesic properties, reducing the "malaise" feeling underlying depressive symptoms. Necessity of a second messanger -- accordingly to current pathophysiological theories, depression results from disorders of various CNS functions, mainly limbic, monaminergic and neuroendocrinal systems. Though, exogenous IFNalpha does not cross the blood-brain barrier when unscathed and an intermediary mechanism is necessary. First to be addressed is the cytokines system itself since it is composed of numerous different molecules interacting in an infinite number of possible combinations. Some of these cytokines (eg some interleukins) both are activated by IFNalpha and can reach CNS; they are good candidates for the role of second messenger mediating the induction of psychobehavioural disorders. Second, keeping in mind that serotonin is a monoaminergic neurotransmitter classically involved in depression pathophysiology, other works have demonstrated that IFNalpha modulates the peripheral activity of indolamine-dioxygenase -- a regulating enzyme of serotonin metabolism -- possibly through lymphocyte T CD4 activation. Third, other authors have postulated an immune-induced vagal mechanism to explain depression caused by IFNalpha. Action of IFNalpha on the neuroendocrine and on neuromodulating functions: monoaminergic hypothesis -- cytokines could have an influence on the mood through their modulating role on the serotoninergic system. IFNalpha treatment is reported to produce: 1) a decrease in tryptophan availability for serotonin synthesis, 2) a decrease in the 5-HIAA level in the LCR, and 3) a modification of the central serotoninergic receptors. Moreover, selective inhibitors of serotonin transporters are effective to treat or prevent depression caused by IFNalpha. Many studies support the serotonin-transporter hypothesis: in vitro, both IFNalpha and interleukine 4 (IL-4) increases the expression of serotonin transporter gene, IFNalpha increases in the production of IL-4 by mononucleus cells (not found in vivo). Serotoninergic system can also be altered by a peripheral action of IFNalpha on trytophan catabolism by activating a concurrent pathway (known as "kynurenine pathway") to serotonin synthesis. Finally, serotonin-mediated vulnerability to the psychobehavioural effects of IFNalpha could be underlain by a polymorphism of serotonin transporter gene. Concerning the other monoaminergic systems, IFNalpha seems to have an amphetamine-like effect at its first administration, followed by a decrease in dopaminergic tone with chronic administration. Dopaminergic depletion, subsequent to psychostimulant abuse for instance, results in severe depressive syndromes. Interactions between IFNalpha and noradrenergic system have also been reported. Neuroendocrinian hypothesis -- when administered through central or peripheral way, IFNalpha simulates/inhibits the corticotrope axis and alters endorphin system as shown by the induction of analgesia, catatonia and behavioural slowdown that can be suppressed by opioid antagonists. IFNalpha neurotoxic effects are successfully treated by naltrexone. Lastly, IFNalpha is known to cause disorders in thyroid function that are likely to contribute to the production or aggravation of mood disorders. CONCLUSION: A better understanding of pathophysiologic mechanisms underlying psychiatric side-effects of IFNalpha is essential to extend access to treatment to some categories of patients that remain excluded from the protocols. A better management of those psychiatric side effects should help the clinician not to draw aside patients at risk, ie patients with depression, drug and alcohol addiction. Treating them in a pragmatic and careful way is a major issue, since this population represents a high percentage of the potential candidates for interferon therapy.

Human narcolepsy is a chronic sleep disorder affecting 1:2000 individuals. The disease is characterized by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep, such as sleep paralysis and hypnagogic hallucinations. Recently, it was discovered that the pathophysiology of (idiopathic) narcolepsy-cataplexy is linked to hypocretin ligand deficiency in the brain and cerebrospinal fluid (CSF), as well as the positivity of the human leukocyte antigen (HLA) DR2/DQ6 (DQB1*0602). The symptoms of narcolepsy can also occur during the course of other neurological conditions (i.e. symptomatic narcolepsy). We define symptomatic narcolepsy as those cases that meet the International Sleep Disorders Narcolepsy Criteria, and which are also associated with a significant underlying neurological disorder that accounts for excessive daytime sleepiness (EDS) and temporal associations. To date, we have counted 116 symptomatic cases of narcolepsy reported in literature. As, several authors previously reported, inherited disorders (n=38), tumors (n=33), and head trauma (n=19) are the three most frequent causes for symptomatic narcolepsy. Of the 116 cases, 10 are associated with multiple sclerosis, one case of acute disseminated encephalomyelitis, and relatively rare cases were reported with vascular disorders (n=6), encephalitis (n=4) and degeneration (n=1), and hererodegenerative disorder (three cases in a family). EDS without cataplexy or any REM sleep abnormalities is also often associated with these neurological conditions, and defined as symptomatic cases of EDS. Although it is difficult to rule out the comorbidity of idiopathic narcolepsy in some cases, review of the literature reveals numerous unquestionable cases of symptomatic narcolepsy. These include cases with HLA negative and/or late onset, and cases in which the occurrences of the narcoleptic symptoms are parallel with the rise and fall of the causative disease. A review of these cases (especially those with brain tumors), illustrates a clear picture that the hypothalamus is most often involved. Several cases of symptomatic cataplexy (without EDS) were also reported and in contrast, these cases appear to be often associated with non-hypothalamic structures. CSF hypocretin-1 measurement were also carried out in a limited number of symptomatic cases of narcolepsy/EDS, including narcolepsy/EDS associated with tumors (n=5), head trauma (n=3), vascular disorders (n=5), encephalopathies (n=3), degeneration (n=30), demyelinating disorder (n=7), genetic/congenital disorders (n=11) and others (n=2). Reduced CSF hypocretin-1 levels were seen in most symptomatic narcolepsy cases of EDS with various etiologies and EDS in these cases is sometimes reversible with an improvement of the causative neurological disorder and an improvement of the hypocretin status. It is also noted that some symptomatic EDS cases (with Parkinson diseases and the thalamic infarction) appeared, but they are not linked with hypocretin ligand deficiency. In contrast to idiopathic narcolepsy cases, an occurrence of cataplexy is not tightly associated with hypocretin ligand deficiency in symptomatic cases. Since CSF hypocretin measures are still experimental, cases with sleep abnormalities/cataplexy are habitually selected for CSF hypocretin measures. Therefore, it is still not known whether all or a large majority of cases with low CSF hypocretin-1 levels with CNS interventions, exhibit EDS/cataplexy. It appears that further studies of the involvement of the hypocretin system in symptomatic narcolepsy and EDS are helpful to understand the pathophysiological mechanisms for the occurrence of EDS and cataplexy.

The finding of orexin (hypocretin) deficiency in patients with narcolepsy suggests that this hypothalamic neuropeptide plays a crucial role in regulating and maintaining sleep/wakefulness states and energy homeostasis. Orexin might be especially important for stabilization of behavioral states, because the major symptom in narcolepsy is instability of each behavioral state, which results in sleep/wakefulness fragmentation. The efferent and afferent systems of orexin neurons suggest interactions between these cells and arousal/sleep-wakefulness centers in the brainstem as well as important feeding centers in the hypothalamus. Electrophysiological studies have shown that orexin neurons are regulated by monoamines and acetylcholine as well as metabolic cues, including leptin, glucose, and ghrelin. Thus, orexin neurons have the requisite functional interactions with hypothalamic feeding pathways and monoaminergic/cholinergic centers, and provide a critical link between peripheral energy balance and the central mechanisms that coordinate sleep/wakefulness and motivated behavior such as food seeking.

We investigated whether depressed muscle Na(+)-K(+)-ATPase activity with exercise reflected a loss of Na(+)-K(+)-ATPase units, the time course of its recovery postexercise, and whether this depressed activity was related to increased Na(+)-K(+)-ATPase isoform gene expression. Fifteen subjects performed fatiguing, knee extensor exercise at approximately 40% maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue, 3 h, and 24 h postexercise and analyzed for maximal Na(+)-K(+)-ATPase activity via 3-O-methylfluorescein phosphatase (3-O-MFPase) activity, Na(+)-K(+)-ATPase content via [(3)H]ouabain binding sites, and Na(+)-K(+)-ATPase alpha(1)-, alpha(2)-, alpha(3)-, beta(1)-, beta(2)- and beta(3)-isoform mRNA expression by real-time RT-PCR. Exercise [352 (SD 267) s] did not affect [(3)H]ouabain binding sites but decreased 3-O-MFPase activity by 10.7 (SD 8)%(P < 0.05), which had recovered by 3 h postexercise, without further change at 24 h. Exercise elevated alpha(1)-isoform mRNA by 1.5-fold at fatigue (P < 0.05). This increase was inversely correlated with the percent change in 3-O-MFPase activity from rest to fatigue (%Delta3-O-MFPase(rest-fatigue))(r =-0.60, P < 0.05). The average postexercise (fatigue, 3 h, 24 h) alpha(1)-isoform mRNA was increased 1.4-fold (P < 0.05) and approached a significant inverse correlation with %Delta3-O-MFPase(rest-fatigue)(r =-0.56, P = 0.08). Exercise elevated alpha(2)-isoform mRNA at fatigue 2.5-fold (P < 0.05), which was inversely correlated with %Delta3-O-MFPase(rest-fatigue)(r =-0.60, P = 0.05). The average postexercise alpha(2)-isoform mRNA was increased 2.2-fold (P < 0.05) and was inversely correlated with the %Delta3-O-MFPase(rest-fatigue)(r =-0.68, P < 0.05). Nonsignificant correlations were found between %Delta3-O-MFPase(rest-fatigue) and other isoforms. Thus acute exercise transiently decreased Na(+)-K(+)-ATPase activity, which was correlated with increased Na(+)-K(+)-ATPase gene expression. This suggests a possible signal-transduction role for depressed muscle Na(+)-K(+)-ATPase activity with exercise.

Histone deacetylase 4 (HDAC4) negatively regulates skeletal myogenesis by associating with the myocyte enhancer factor 2 (MEF2) transcription factors. Our data indicate that the gene PC4 (interferon-related developmental regulator 1 [IFRD1], Tis7), which we have previously shown to be required for myoblast differentiation, is both induced by MyoD and potentiates the transcriptional activity of MyoD, thus revealing a positive regulatory loop between these molecules. Enhancement by PC4 of MyoD-dependent activation of muscle gene promoters occurs selectively through MEF2 binding sites. Furthermore, PC4 localizes in the nucleus of differentiating myoblasts, associates with MEF2C, and is able to counteract the HDAC4-mediated inhibition of MEF2C. This latter action can be explained by the observed ability of PC4 to dose dependently displace HDAC4 from MEF2C. Consistently, we have observed that (i) the region of PC4 that binds MEF2C is sufficient to counteract the inhibition by HDAC4;(ii) PC4, although able to bind HDAC4, does not inhibit the enzymatic activity of HDAC4; and (iii) PC4 overcomes the inhibition mediated by the amino-terminal domain of HDAC4, which associates with MEF2C but not with PC4. Together, our findings strongly suggest that PC4 acts as a coactivator of MyoD and MEF2C by removing the inhibitory effect of HDAC4, thus exerting a pivotal function during myogenesis.