Detection of enterovirus in human skeletal muscle from patients with chronic inflammatory muscle disease or fibromyalgia and healthy subjects

Umbilical Cord Mesenchymal-Stem-Cell-Derived Exosomes Exhibit Anti-Oxidant and Antiviral Effects as Cell-Free Therapies

The oxidative stress induced by the accumulation of reactive oxygen species (ROS) can lead to cell aging and death. Equally, the skeletal muscle usually hosts enteroviral persistent infection in inflammatory muscle diseases. As excellent bioactive products, the exosomes derived from umbilical cord mesenchymal stem cells (ucMSCs) have been proven to be safe and have low immunogenicity with a potential cell-free therapeutic function. Here, exosomes derived from ucMSCs (ucMSC-EXO) were extracted and characterized. In a model of oxidative damage to skin fibroblasts (HSFs) under exposure to H2O2, ucMSC-EXO had an observable repairing effect for the HSFs suffering from oxidative damage. Furthermore, ucMSC-EXO inhibited mitogen-activated protein kinases (MAPK), c-Jun N-terminal kinase (JNK), and nuclear factor kappa-B (NF-κB) signaling pathways, thereby promoting p21 protein expression while decreasing lamin B1 protein expression, and finally alleviated oxidative stress-induced cell damage and aging. In a model of rhabdomyosarcoma (RD) cells being infected by enterovirus 71 (EV71) and coxsackievirus B3 (CVB3), the ucMSC-EXO enhanced the expression of interferon-stimulated gene 15 (ISG15) and ISG56 to inhibit enteroviral replication, whereafter reducing the virus-induced proinflammatory factor production. This study provides a promising therapeutic strategy for ucMSC-EXO in anti-oxidative stress and antiviral effects, which provides insight into extending the function of ucMSC-EXO in cell-free therapy.

A Mouse-adapted CVA6 Strain Exhibits Neurotropism and Triggers Systemic Manifestations in a Novel Murine Model

CVA6 is one of Enteroviruses causing worldwide epidemics of HFMD with neurological and systemic complications. A suitable animal model is necessary for studying the pathogenesis of CVA6 and evaluating antiviral and vaccine efficacy. In this study, we generated a mouse-adapted CVA6 strain that successfully infected 10-day-old ICR mice via oral route. All infected mice were paralyzed and died within 11 dpi. Analysis of pathological changes and virus loads in fourteen tissues showed that CVA6 triggered systematic damage similar to i.p. inoculation route. Unlike i.p. route, we detected oral and gastrointestinal lesions with the presence of viral antigens. Both specific anti-CVA6 serum and inactivated vaccines successfully generated immune protection in mice. Meanwhile, we also established a successful infection of CVA6 via i.p. and i.m. route in 10-day-old mice. After infection, mice developed remarkably neurological signs and systemic manifestations such as emaciation, polypnea, quadriplegia, depilation and even death. Through i.p. inoculation, pathological examination showed brain and spinal cord damage caused by the virus infection with neuronal reduction, apoptosis, astrocyte activation, and recruitment of neutrophils and monocytes. Following neurological manifestation, the CVA6 infection became systemic, and high viral loads were detected in multiple organs along with morphological changes and inflammation. Moreover, analysis of spleen cells by FACS indicated that CVA6 led to immune system activation, which further contributed to systemic inflammation. Taken together, our novel murine model of CVA6 provides a useful tool for studying the pathogenesis and evaluating antiviral and vaccine efficacy.

Human enteroviral infection in fibromyalgia: a case-control blinded study

OBJECTIVE

This study aimed to test the hypothesis that fibromyalgia is associated with a human enteroviral infection.

METHODS

Venous peripheral blood samples from 27 patients fulfilling the American College of Rheumatology revised diagnostic criteria for fibromyalgia and from 26 age- and sex-matched controls, who underwent immunofluorescence assays for coxsackievirus A7 IgG, coxsackievirus B1 IgG, coxsackievirus A7 IgA, coxsackievirus B1 IgA, echovirus IgG, and echovirus IgA. These immunological tests were performed blind to group status.

RESULTS

There were no significant differences between the patient and control groups in respect of positive results for coxsackievirus A7 IgG (p=0.467), coxsackievirus B1 IgG (p=0.491), coxsackievirus A7 IgA (p=0.586), coxsackievirus B1 IgA (p=0.467), echovirus IgG (p=0.236), and echovirus IgA (p=1).

CONCLUSIONS

The results of this systematic study do not support the hypothesis that fibromyalgia is associated with infection by a human enterovirus.

Seasonal Effect on Disease Onset and Presentation in Anti-MDA5 Positive Dermatomyositis

Objective

To investigate the seasonal variation of disease onset and presentation in an ethno-geographically homogeneous cohort of patients with anti-MDA5 positive dermatomyositis (DM).

Methods

This was a multi-centered, retrospective cohort study. Adult Chinese anti-MDA5 positive DM patients were identified from the Hong Kong Myositis Registry and the Clinical Data Analysis and Reporting System from 2015 to 2020. Equal number of IIM patients without anti-MDA5 antibody were selected as controls. Line blot immunoassay was used to detect the autoantibodies. The onset of disease, presenting clinical features and subsequent complications were analyzed for any seasonality.

Results

A total of 110 patients with anti-MDA5 positive DM were studied. The mean age at diagnosis was 53.0 ± 12.3 years and the mean follow-up duration was 20.6 ± 23.1 months. Two third of the patients (66%) had the clinically amyopathic phenotype. Most patients (86%) had interstitial lung disease (ILD) and 42% developed rapidly progressive ILD (RP-ILD). The mortality was 40% and the commonest cause was RP-ILD. Chi-square test showed significantly less patients had symptom onset in July to September. However, no particular seasonal pattern was observed in the anti-MDA5 negative IIM controls. RP-ILD occurred more frequently in patients with disease onset in October to December. Anti-MDA5 positive DM patients with disease onset in warmer months (April to September) were more likely to have clinical muscle involvement.

Conclusion

Apparent seasonal patterns were noted in our ethno-geographically identical anti-MDA5 positive DM patients, but not in IIM patients in general. Certain environmental factors, particularly infection, might be implicated.

The Enterovirus Theory of Disease Etiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Critical Review

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex, multi-system disease whose etiological basis has not been established. Enteroviruses (EVs) as a cause of ME/CFS have sometimes been proposed, as they are known agents of acute respiratory and gastrointestinal infections that may persist in secondary infection sites, including the central nervous system, muscle, and heart. To date, the body of research that has investigated enterovirus infections in relation to ME/CFS supports an increased prevalence of chronic or persistent enteroviral infections in ME/CFS patient cohorts than in healthy individuals. Nevertheless, inconsistent results have fueled a decline in related studies over the past two decades. This review covers the aspects of ME/CFS pathophysiology that are consistent with a chronic enterovirus infection and critically reviews methodologies and approaches used in past EV-related ME/CFS studies. We describe the prior sample types that were interrogated, the methods used and the limitations to the approaches that were chosen. We conclude that there is considerable evidence that prior outbreaks of ME/CFS were caused by one or more enterovirus groups. Furthermore, we find that the methods used in prior studies were inadequate to rule out the presence of chronic enteroviral infections in individuals with ME/CFS. Given the possibility that such infections could be contributing to morbidity and preventing recovery, further studies of appropriate biological samples with the latest molecular methods are urgently needed.

A Review of Myofascial Pain and Fibromyalgia – Factors that Promote Their Persistence

Chronic muscle pain (myalgia) is a common problem throughout the world. Seemingly simple, it is actually a difficult problem for the clinician interested in determining the aetiology of the pain, as well as in managing the pain. The two common muscle pain conditions are fibromyalgia and myofascial pain syndrome. Fibromyalgia is a chronic, widespread muscle tenderness syndrome, associated with central sensitisation. It is often accompanied by chronic sleep disturbance and fatigue, visceral pain syndromes like irritable bowel syndrome and interstitial cystitis. Myofascial pain syndrome is an overuse or muscle stress syndrome characterised by the presence of trigger points in muscle. The problem these syndromes pose lies not in making the diagnosis of muscle pain. Rather, it is the need to identify the underlying cause(s) of persistent or chronic muscle pain in order to develop a specific treatment plan. Chronic myalgia may not improve until the underlying precipitating or perpetuating factor(s) are themselves managed. Precipitating or perpetuating causes of chronic myalgia include structural or mechanical causes like scoliosis, localised joint hypomobility, or generalised or local joint laxity; and metabolic factors like depleted tissue iron stores, hypothyroidism or Vitamin D deficiency. Sometimes, correction of an underlying cause of myalgia is all that is needed to resolve the condition.

Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Background and main text

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and controversial clinical condition without having established causative factors. Increasing numbers of cases during past decade have created awareness among patients as well as healthcare professionals. Chronic viral infection as a cause of ME/CFS has long been debated. However, lack of large studies involving well-designed patient groups and validated experimental set ups have hindered our knowledge about this disease. Moreover, recent developments regarding molecular mechanism of pathogenesis of various infectious agents cast doubts over validity of several of the past studies.

Conclusions

This review aims to compile all the studies done so far to investigate various viral agents that could be associated with ME/CFS. Furthermore, we suggest strategies to better design future studies on the role of viral infections in ME/CFS.

Pulmonary edema following central nervous system lesions induced by a non- mouse-adapted EV71 strain in neonatal BALB/c mice

Background

Enterovirus (EV) infection has been a serious health issue in Asia-Pacific region. It has been indicated that the occurrence of fatal hand foot and mouth disease (HFMD) cases following EV71 infection is mainly attributed to pulmonary edema. However, the development of pulmonary disorders after EV71 infection remains largely unknown. To establish an EV71-infected animal model and further explore the underlying association of central nervous system (CNS) invasion with pulmonary edema, we isolated a clinical source EV71 strain (ZZ1350) from a severe case in Henan Province.

Methods

We evaluated the cytotoxicity of ZZ1350 strain and the susceptibility in 3-day-old BALB/c mice with intraperitoneal, intracerebral and intramuscular inoculation. Various histopathological and immunohistochemical techniques were applied to determine the target organs or tissue damage after infection. Correlation analysis was used to identify the relationship between CNS injury and pulmonary disorders.

Results

Our experimental results suggested that ZZ1350 (C4 subtype) had high cytotoxicity against African green monkey kidney (Vero) cells and human rhabdomyosarcoma (RD) cells and neonatal BALB/c mice were highly susceptible to the infection with ZZ1350 through three different inoculation routes (2 × 10⁶ pfu/mouse) exhibiting severe neurological and respiratory symptoms that were similar to clinical observation. Viral replication was found in brain, spinal cord, skeletal muscle, lung, spleen, liver, heart of infected mice and these sections also showed histopathological changes. We found that brain histology score was positive correlated with lung histology score in total experimental mice and mice under the three inoculation routes (P < 0.05). At the same time, there were positive correlations between spinal cord score and lung score in total experimental mice and mice with intracerebral inoculation (P < 0.05).

Conclusions

ZZ1350 strain is effective to establish animal model of EV71 infection with severe neurological and respiratory symptoms. The development of pulmonary disorders after EV71 infection is associated with severity of CNS damage.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12985-017-0911-5) contains supplementary material, which is available to authorized users.

Infections and respiratory tract disease as risk factors for idiopathic inflammatory myopathies: a population-based casecontrol study

OBJECTIVES

To investigate the association between infection or respiratory tract disease and future risk of developing idiopathic inflammatory myopathy (IIM).

METHODS

A case-control study was performed using Swedish nationwide registers. Adults with newly diagnosed IIM were identified (2002-2011) from the National Patient Register (NPR) and the Swedish Rheumatology Register (n=957). Controls were matched by age, sex and place of residence (n=9476). Outpatient visits and hospitalisations preceding IIM diagnosis indicating infection or respiratory disease were identified from NPR. Conditional logistic regression models were used to calculate OR and 95% CI. Sensitivity analyses were performed by varying the exposure definition, adjusting for previous healthcare consumption and excluding individuals with connective tissue disease, IIM lung phenotype or IIM-associated cancer.

RESULTS

Preceding infections were more common in IIM cases compared with controls (13% vs 9%) and were associated with an increased risk of IIM (OR 1.5, 95% CI 1.2 to 1.9). Gastrointestinal and respiratory tract infections were associated with an increased risk of IIM while cutaneous infections were not.Preceding respiratory tract disease was present in 10% of IIM cases and 4% of controls (OR 2.3, 95% CI 1.8 to 3.0). Both upper and lower respiratory tract diseases were associated with an increased risk of IIM.Variations in exposure and outcome definitions did not greatly affect the results.

CONCLUSIONS

Infections and respiratory tract diseases are associated with an increased risk of IIM which suggests that the triggering of the immune system may take place outside the skeletal muscle.

Functional Consequences of RNA 5'-Terminal Deletions on Coxsackievirus B3 RNA Replication and Ribonucleoprotein Complex Formation

Group B coxsackieviruses are responsible for chronic cardiac infections. However, the molecular mechanisms by which the virus can persist in the human heart long after the signs of acute myocarditis have abated are still not completely understood. Recently, coxsackievirus B3 strains with 5'-terminal deletions in genomic RNAs were isolated from a patient suffering from idiopathic dilated cardiomyopathy, suggesting that such mutant viruses may be the forms responsible for persistent infection. These deletions lacked portions of 5' stem-loop I, which is an RNA secondary structure required for viral RNA replication. In this study, we assessed the consequences of the genomic deletions observed in vivo for coxsackievirus B3 biology. Using cell extracts from HeLa cells, as well as transfection of luciferase replicons in two types of cardiomyocytes, we demonstrated that coxsackievirus RNAs harboring 5' deletions ranging from 7 to 49 nucleotides in length can be translated nearly as efficiently as those of wild-type virus. However, these 5' deletions greatly reduced the synthesis of viral RNA in vitro, which was detected only for the 7- and 21-nucleotide deletions. Since 5' stem-loop I RNA forms a ribonucleoprotein complex with cellular and viral proteins involved in viral RNA replication, we investigated the binding of the host cell protein PCBP2, as well as viral protein 3CD^pro, to deleted positive-strand RNAs corresponding to the 5' end. We found that binding of these proteins was conserved but that ribonucleoprotein complex formation required higher PCBP2 and 3CD^pro concentrations, depending on the size of the deletion. Overall, this study confirmed the characteristics of persistent CVB3 infection observed in heart tissues and provided a possible explanation for the low level of RNA replication observed for the 5'-deleted viral genomes-a less stable ribonucleoprotein complex formed with proteins involved in viral RNA replication.IMPORTANCE Dilated cardiomyopathy is the most common indication for heart transplantation worldwide, and coxsackie B viruses are detected in about one-third of idiopathic dilated cardiomyopathies. Terminal deletions at the 5' end of the viral genome involving an RNA secondary structure required for RNA replication have been recently reported as a possible mechanism of virus persistence in the human heart. These mutations are likely to disrupt the correct folding of an RNA secondary structure required for viral RNA replication. In this report, we demonstrate that transfected RNAs harboring 5'-terminal sequence deletions are able to direct the synthesis of viral proteins, but not genomic RNAs, in human and murine cardiomyocytes. Moreover, we show that the binding of cellular and viral replication factors to viral RNA is conserved despite genomic deletions but that the impaired RNA synthesis associated with terminally deleted viruses could be due to destabilization of the ribonucleoprotein complexes formed.

Human enterovirus in the gastrocnemius of patients with peripheral arterial disease

Background

Peripheral arterial disease (PAD) is characterized by myofiber degeneration and loss of function in muscles of the lower limbs. Human enterovirus (HEV) infection has been implicated in the pathogenesis of a number of muscle diseases. However, its association with PAD has not been studied. In this study, we tested the hypothesis that infectious HEV is present in skeletal muscle of patients with PAD and is associated with severity of disease.

Methods and Results

Gastrocnemius biopsies from 37 patients with PAD and 14 controls were examined for the presence of HEV RNA, viral capsid protein, viral RNA copy number, and viral infectivity. HEV RNA was detected in 54% of the biopsies from patients with PAD but was not detected in muscle biopsies from control patients. This difference in prevalence among PAD and control patients was significant at P<0.001. Viral RNA copy numbers were increased significantly at the later stages of disease; Fontaine Stage IV (10^5.50 copies/mg muscle wet weight, at P<0.005) and Stage III (10^4.87 copies/mg, at P<0.010) compared to Stage II (10^2.50 copies/mg). Viral replication was confirmed by the presence of the negative‐strand of viral RNA in all specimens positive for HEV RNA. Cultures of HeLa and human skeletal muscle cells treated with muscle homogenates showed HEV replication and the presence of HEV capsid protein.

Conclusion

Our data identified infectious HEV in the gastrocnemius of PAD patients but not in controls. Viral copy number and prevalence of infection were higher in the later stages of disease. Our data point to the need for further studies to determine the contribution of HEV infection to the pathophysiology of PAD.

Mouse adaptation of a sub-genogroup B5 strain of human enterovirus 71 is associated with a novel lysine to glutamic acid substitution at position 244 in protein VP1

Most human enterovirus 71 (HEV71) strains infect only primates and are unable to cause clinically apparent infection in mice. Here we describe a mouse-adapted HEV71 strain that belongs to sub-genogroup B5 with increased virulence in newborn BALB/c mice. The mouse-virulent strain was initially selected by serial passage of a HEV71 clinical isolate (HEV71-B5) in Chinese hamster ovary (CHO) cells (CHO-B5), followed by serial passage in newborn mice. Virus from the fifth mouse passage was cultured twice on Vero cells and designated as MP-B5. MP-B5 induces severe disease of high mortality in newborn mice in a dose-dependent manner. Skeletal muscle is the primary site of virus replication and results in severe myositis. CHO-B5 harbours a single amino acid substitution (K(149) → I) in the VP2 capsid protein. Five additional nucleotide sequence changes were identified in MP-B5, two of which are located in the 5' UTR and the three within the open reading frame (ORF). Two of the ORF mutations resulted in deduced amino acid changes in the capsid protein VP1: S(241) → L and K(244) → E; the third ORF mutation was a synonymous C → T change at nucleotide position 6072 within the 3D polymerase gene. Infectious cDNA clone-derived mutant virus populations of HEV71 belonging to sub-genogroup B3 (CHO-26 M) that contain the VP1 mutations identified in MP-B5 were generated in order to determine the mutation(s) responsible for mouse virulence. Only viruses expressing the VP1 (K(244) → E) mutation were virulent in 5-day-old BALB/c mice, indicating that the VP1 (K(244) → E) change is the critical genetic determinant of mouse adaptation and virulence in this model.

A non-mouse-adapted enterovirus 71 (EV71) strain exhibits neurotropism, causing neurological manifestations in a novel mouse model of EV71 infection

Enterovirus 71 (EV71) is a neurotropic pathogen that has been consistently associated with the severe neurological forms of hand, foot, and mouth disease. The lack of a relevant animal model has hampered our understanding of EV71 pathogenesis, in particular the route and mode of viral dissemination. It has also hindered the development of effective prophylactic and therapeutic approaches, making EV71 one of the most pressing public health concerns in Southeast Asia. Here we report a novel mouse model of EV71 infection. We demonstrate that 2-week-old and younger immunodeficient AG129 mice, which lack type I and II interferon receptors, are susceptible to infection with a non-mouse-adapted EV71 strain via both the intraperitoneal (i.p.) and oral routes of inoculation. The infected mice displayed progressive limb paralysis prior to death. The dissemination of the virus was dependent on the route of inoculation but eventually resulted in virus accumulation in the central nervous systems of both animal groups, indicating a clear neurotropism of the virus. Histopathological examination revealed massive damage in the limb muscles, brainstem, and anterior horn areas. However, the minute amount of infectious viral particles in the limbs from orally infected animals argues against a direct viral cytopathic effect in this tissue and suggests that limb paralysis is a consequence of EV71 neuroinvasion. Together, our observations support that young AG129 mice display polio-like neuropathogenesis upon infection with a non-mouse-adapted EV71 strain, making this mouse model relevant for EV71 pathogenesis studies and an attractive platform for EV71 vaccine and drug testing.

The common immunogenic etiology of chronic fatigue syndrome: from infections to vaccines via adjuvants to the ASIA syndrome

Chronic fatigue syndrome (CFS) is characterized by unexplained fatigue that lasts for at least 6 months with a constellation of other symptoms. Most cases start suddenly, and are usually accompanied by a flu-like illness. It is a symptom-based diagnosis of exclusion, the pathogenesis of which is unknown. Studies have examined and hypothesized about the possible biomedical and epidemiologic characteristics of the disease, including genetic predisposition, infections, endocrine abnormalities, and immune dysfunction and psychological and psychosocial factors. Recently, the AISA (autoimmune/inflammatory syndrome induced by adjuvants) syndrome was recognized, indicating the possible contribution of adjuvants and vaccines to the development of autoimmunity.

A mouse muscle-adapted enterovirus 71 strain with increased virulence in mice

Enterovirus 71 (EV71) infections can usually cause epidemic hand, foot, and mouth disease (HFMD), and occasionally lead to aseptic meningitis, encephalitis, and polio-like illness. Skeletal muscles have been thought to be crucial for the pathogenesis of EV71-related diseases. However, little is known about the virulence of mouse muscle-adapted EV71. The EV71 0805 were subjected to four passages in the mouse muscle to generate a mouse-adapted EV71 strain of 0805a. In comparison with the parental EV71 0805, the mouse muscle-adapted EV71 0805a displayed stronger cytotoxicity against Rhabdomyosarcoma (RD) cells and more efficient replication in RD cells. Furthermore, infection with the EV71 0805a significantly inhibited the gain of body weight, accompanied by increased muscle virus load and multiple tissue distribution in the infected mouse. Histological examinations indicated that infection with the EV71 0805 did not cause obvious pathogenic lesions in mice, while infection with the muscle-adapted 0805a resulted in severe necrotizing myositis in the skeletal and cardio muscles, and intestinitis in mice on day 5 post infection. Further analysis revealed many mutations in different regions of the genome of mouse muscle-adapted virus. Collectively, these data demonstrated the mouse muscle-adapted EV71 0805a with increased virulence in mice.

Idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies are a group of systemic autoimmune syndromes characterized by striated muscle inflammation. Here, we discuss the clinical features of this group of conditions and review the recent developments in the understanding of the pathogenesis and immunogenetics of the idiopathic inflammatory myopathies. The role of myositis-specific autoantibodies and their clinical significance and an overview of management are also provided.

Interactions between multiple genetic determinants in the 5' UTR and VP1 capsid control pathogenesis of chronic post-viral myopathy caused by coxsackievirus B1

Mice infected with coxsackievirus B1 Tucson (CVB1(T)) develop chronic, post-viral myopathy (PVM) with clinical manifestations of hind limb muscle weakness and myositis. The objective of the current study was to establish the genetic basis of myopathogenicity in CVB1(T). Using a reverse genetics approach, full attenuation of PVM could only be achieved by simultaneously mutating four sites located at C706U in the 5' untranslated region (5' UTR) and at Y87F, V136A, and T276A in the VP1 capsid. Engineering these four myopathic determinants into an amyopathic CVB1(T) variant restored the ability to cause PVM. Moreover, these same four determinants controlled PVM expression in a second strain of mice, indicating that the underlying mechanism is operational in mice of different genetic backgrounds. Modeling studies predict that C706U alters both local and long range pairing in the 5' UTR, and that VP1 determinants are located on the capsid surface. However, these differences did not affect viral titers, temperature stability, pH stability, or the antibody response to virus. These studies demonstrate that PVM develops from a complex interplay between viral determinants in the 5' UTR and VP1 capsid and have uncovered intriguing similarities between genetic determinants that cause PVM and those involved in pathogenesis of other enteroviruses.

Retrograde axonal transport: a major transmission route of enterovirus 71 in mice

Inoculation of enterovirus 71 (EV71) by the oral (p.o.), intramuscular (i.m.), or intracranial route resulted in brain infection, flaccid paralysis, pulmonary dysfunction, and death of 7-day-old mice. The lag time of disease progression indicated that neuroinvasion from the inoculation sites was a prerequisite for the development of the clinical signs. Although EV71 p.o. inoculation led to a persistent viremia and a transient increase in blood-brain barrier permeability at the early stage of the infection, only low levels of virus, which led to neither severe infection nor clinical illness, could be detected in the brain, suggesting that hematogenous transport might not represent a major transmission route. In the spinal cord, following both p.o. and hind limb i.m. inoculation, the virus first appeared and increased rapidly in the lower segments, especially at the anterior horn areas, and then spread to the upper segments and brain in the presence of viremia. A reverse pattern, with the virus being first detected in the upper segment, was observed when the virus was i.m. inoculated in the forelimb. Colchicine, a fast axonal transport inhibitor, but not sciatic nerve transection reduced EV71 neuroinvasion in a dose-dependent manner, indicating a neuronal transmission of the virus.

Transcriptomic and proteomic analyses of rhabdomyosarcoma cells reveal differential cellular gene expression in response to enterovirus 71 infection

Insights into the host antiviral strategies as well as viral disease manifestations can be achieved through the elucidation of host- and virus-mediated transcriptional responses. An oligo-based microarray was employed to analyse mRNAs from rhabdomyosarcoma cells infected with the MS/7423/87 strain of enterovirus 71 (EV71) at 20 h post infection. Using Acuity software and LOWESS normalization, 152 genes were found to be downregulated while 39 were upregulated by greater than twofold. Altered transcripts include those encoding components of cytoskeleton, protein translation and modification; cellular transport proteins; protein degradation mediators; cell death mediators; mitochondrial-related and metabolism proteins; cellular receptors and signal transducers. Changes in expression profiles of 15 representative genes were authenticated by real-time reverse transcription polymerase chain reaction (RT-PCR), which also compared the transcriptional responses of cells infected with EV71 strain 5865/Sin/000009 isolated from a fatal case during the Singapore outbreak in 2000. Western blot analyses of APOB, CLU, DCAMKL1 and ODC1 proteins correlated protein and transcript levels. Two-dimensional proteomic maps highlighted differences in expression of cellular proteins (CCT5, CFL1, ENO1, HSPB1, PSMA2 and STMN1) following EV71 infection. Expression of several apoptosis-associated genes was modified, coinciding with apoptosis attenuation observed in poliovirus infection. Interestingly, doublecortin and CaM kinase-like 1 (DCAMKL1) involved in brain development, was highly expressed during infection. Thus, microarray, real-time RT-PCR and proteomic analyses can elucidate the global view of the numerous and complex cellular responses that contribute towards EV71 pathogenesis.

The role of enterovirus in chronic fatigue syndrome

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.

Evaluation of maximal exercise performance, fatigue, and depression in athletes with acquired chronic training intolerance

OBJECTIVE

This study compared differences in maximal strength and aerobic capacity and symptoms of fatigue and depression in athletes with acquired training intolerance (ATI) and control athletes (CON) matched for age and current training volume who did not have symptoms of excessive or chronic fatigue associated with their sporting activity.

SETTING

University of Cape Town, Sports Science Institute of South Africa.

PARTICIPANTS

Twenty ATI and 10 CON athletes participated in the trial. Although the ATI athletes reported symptoms of excessive fatigue during exercise, or symptoms of fatigue that occurred at rest and during activities of daily living, they did not fulfill the criteria for a diagnosis of chronic fatigue syndrome.

MAIN OUTCOME MEASURES

A training and comprehensive medical history was recorded from all subjects. The Beck Depression Inventory Short Form (BDI-SF) was used to assess levels of depression in both ATI and control subjects. Maximal force output during a 5-second isometric voluntary knee extensor muscle contraction, and maximal aerobic capacity (VO2max), maximal heart rate (HRmax), and maximal blood lactate concentrations during a treadmill running test were measured in all subjects.

RESULTS

There were no differences in maximal isometric force output, peak treadmill running speed, VO2max, HRmax, or blood lactate concentration at rest or after maximal exercise testing between the ATI and CON athletes. However, the BDI-SF scores were higher in the ATI (7.7 +/- 6.6 arbitrary units) than in the CON athletes (1.7 +/- 1.5 arbitrary units; (P = 0.0052).

CONCLUSIONS

These findings suggest that the symptoms of excessive fatigue and acquired training intolerance described by these ATI athletes do not affect their maximal isometric and maximal aerobic capacity, and may be associated with psychologic depression in these athletes.

Myositis: an update on pathogenesis

PURPOSE OF REVIEW

The etiology and much about the pathogenesis of the inflammatory myopathies remain a mystery. In this review, we investigate recent research efforts to understand the pathogenesis of the diverse entities of polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM), diseases that result from interactions between environmental risk factors and genetic susceptibility.

RECENT FINDINGS

Over the past year, there has been considerable progress toward better understanding of IBM, with relatively few developments toward understanding PM and DM. Although these diseases may share some common clinical phenotypic and serologic components, they differ on a molecular and cellular level.

SUMMARY

The need for definitive, safer therapies in these diseases makes vital the search for defining detailed pathogenesis of inflammation and muscle fiber damage at the molecular level.

α1-Antitrypsin and fibromyalgia: new data in favour of the inflammatory hypothesis of fibromyalgia

alpha1-Antitrypsin (AAT) circulates in high serum concentrations, and impregnates most body tissues. AAT has a broad anti-inflammatory spectrum, and modulates most inflammatory reactions occurring in human body. Recently, a possible relationship between AAT deficiency (AAT-D) and fibromyalgia (FM) has been raised, with the finding that intravenous infusions of purified human AAT efficiently controlled FM symptoms in two patients with severe hereditary AAT-D. On the other hand, functional magnetic resonance imaging has detected a significant greater activity in pain sensitive areas of the brain in patients with FM, in response to cutaneous stimuli, providing further evidence for a physiological explanation for FM pain. In recent studies abnormal profiles of inflammation markers in serum and biopsies have been found in FM patients. Since most of these inflammation mediators can be inhibited by AAT, these observations would suggest that at least a subset of the FM syndrome could be related to an inflammatory process, possibly due to an imbalance between inflammatory and anti-inflammatory substances, in the soft body tissues. Future directions of research would be: (1) to develop epidemiological studies to determine the gene frequency of AAT deficiency alleles in FM patients; (2) implementation of a double-blind placebo-controlled clinical trial to determine the specific role of AAT augmentation therapy in AAT-D patients with FM; (3) identification of specific laboratory markers for diagnostic and clinical evaluation purposes in FM; (4) application of the newest medical imaging techniques for diagnosis; and (5) identification of genetic, familial, and environmental risk factors suspected to participate in the FM syndrome development.

Seasonal influence on the onset of idiopathic inflammatory myopathies in serologically defined groups

OBJECTIVE

To assess possible seasonal patterns in the onset of polymyositis (PM) and dermatomyositis (DM).

METHODS

The study group comprised 503 patients who met the criteria for probable or definite PM or DM and for whom detailed data on the time of myositis onset were available. Statistical analyses were performed using a Poisson model that assessed associations of ethnicity, sex, autoantibody presence, and month of onset of muscle weakness.

RESULTS

There were no significant seasonal patterns of disease onset in myositis patients as a whole or in the total PM or DM populations. Significant seasonal associations were present, however, in the serologically defined groups. In the 131 patients with antisynthetase autoantibodies who were categorized as non-black, myositis onset peaked in March-April (P = 0.03). Among the antisynthetase-positive patients, the association was predominantly in those with PM (n = 85; P = 0.05) and in men (n = 51; P = 0.042). Patients with anti-signal recognition particle autoantibodies, however, did not have a significant seasonal onset, which is in contrast to previous findings. Patients without myositis-specific autoantibodies showed a significant peak in summer, with myositis onset in June-July (n = 252; P = 0.03); this seasonal association was significant in women (n = 182; P = 0.005), whereas there was no seasonal pattern in men (P = 0.9).

CONCLUSION

These findings, in conjunction with other data, suggest that diverse environmental agents, acting upon different immunogenetic backgrounds, result in distinct immune responses and clinical syndromes in the idiopathic inflammatory myopathies. Our results emphasize the importance of considering more homogeneous disease groups, based on clinicopathologic features, immune responses, ethnicity, and sex, when attempting to decipher the pathogeneses of autoimmune disorders.