Eccentric Resistance Training Ameliorates Muscle Weakness in a Mouse Model of Idiopathic Inflammatory Myopathies.

OBJECTIVE: High-force eccentric contractions (ECCs) have traditionally been excluded from rehabilitation programs that include patients with idiopathic inflammatory myopathies (IIMs) due to unverified fear of causing muscle damage and inflammation. In an IIM animal model that used mice with experimental autoimmune myositis (EAM), we undertook this study to investigate whether ECC training can safely and effectively be used to counteract muscle weakness in IIM. METHODS: EAM was induced in BALB/c mice by immunization with 3 injections of myosin emulsified in Freund's complete adjuvant. Controls (n = 12) and mice with EAM (n = 12) were exposed to either an acute bout of 100 ECCs or 4 weeks of ECC training (20 ECCs every other day). To induce ECCs, plantar flexor muscles were electrically stimulated while the ankle was forcibly dorsiflexed. RESULTS: Less cell damage, as assessed by Evans blue dye uptake, was observed in the muscles of mice with EAM, compared to controls, after an acute bout of 100 ECCs (P < 0.05). Maximum Ca2+ -activated force was decreased in skinned gastrocnemius muscle fibers from mice with EAM, and this was accompanied by increased expression of endoplasmic reticulum (ER) stress proteins, including Gsp78 and Gsp94 (P < 0.05). ECC training prevented the decrease in force and the increase in ER stress proteins and also enhanced the expression and myofibrillar binding of small heat-shock proteins (HSPs) (P < 0.05), which can stabilize myofibrillar structure and function. CONCLUSION: ECC training protected against the reduction in myofibrillar force-generating capacity in an IIM mouse model, and this occurred via inhibition of ER stress responses and small HSP-mediated myofibrillar stabilization.

Upregulated expression of NMDA receptor in the paraventricular nucleus shortens ejaculation latency in rats with experimental autoimmune prostatitis.

BACKGROUND: Estimated 30%-40% of patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) suffer from premature ejaculation (PE), which is difficult to cure, but the mechanism is still unknown. Based on the results of our previous clinical studies and animal experiments, we propose that the glutamatergic system dysfunction in the paraventricular nucleus (PVN) may be involved. METHODS: To test this hypothesis, we used experimental autoimmune prostatitis (EAP) rats to investigate the effects of CP/CPPS on ejaculation behavior through integrating copulatory behavior testing, neuroelectrophysiologic experiments, and molecular biology technologies. RESULTS: Histological examination of prostate tissue in EAP rats exhibited consistent pathological findings with that in CP/CPPS patients. Behavior testing showed that ejaculation latency (EL) of EAP rats significantly shortened compared with the controls (5.1 ± 1.8 vs 9.1 ± 2.4 min, P < .001). Sympathetic nervous system (SNS) activity testing revealed that EAP rats displayed significantly higher plasma norepinephrine (NE) level (1780 ± 493 vs 1421 ± 453 pg/mL, P = .043) and SNS sensitivity (67.8 ± 9.6 vs 44.6 ± 8.7%, P < .001). Immunohistochemical detection and Western blot analysis both displayed that NR1 subunit expression of N-methyl-D-aspartic acid (NMDA) receptors in the PVN of EAP rats was significantly upregulated (P = .007 and P < .001). Furthermore, the expression of NMDA NR1 subunit positively correlated both with SNS sensitivity (r = .917, P < .001) and prostatic inflammation scores (r = .964, P < .001). CONCLUSION: This study shows that EAP rats suffer from the same PE symptom as CP/CPPS patients. CP/CPPS-induced inflammatory-immune response can significantly upregulate the expression of NMDA receptors in the PVN, which shortening the EL by enhancing SNS sensitivity. However, the exact mechanism of chronic inflammation in the prostate causing the upregulated expression of NMDA receptors needs to be further studied.

Pregabalin enhances myelin repair and attenuates glial activation in lysolecithin-induced demyelination model of rat optic chiasm.

Multiple sclerosis (MS) is an autoimmune disease in which more than 70% of patients experience visual disturbance as the earliest symptoms. Lysolecithin (LPC)-induced focal demyelination model has been developed to evaluate the effects of different therapies on myelin repair improvement. In this study, the effects of pregabalin administration on myelin repair and glial activation were investigated. Local demyelination was induced by administration of LPC (1%, 2µL) into the rat optic chiasm. Rats underwent daily injection of pregabalin (30mg/kg, i.p) or vehicle. Visual-evoked potentials (VEPs) recordings were performed for evaluating the function of optic pathway on days 3, 7, 14 and 28 post lesions. Myelin specific staining and immunostaining against GFAP and Iba1 were also carried out for assessment of myelination and glial activation respectively. Electrophysiological data indicated that pregabalin administration could significantly reduce the P1-N1 latency and increase the amplitude of VEPs waves compared to saline group. Luxol fast blue staining and immunostaining against PLP, as mature myelin marker, showed that myelin repair was improved in animals received pregabalin treatment. In addition, pregabalin effectively reduced the expression of GFAP and Iba1 as activated glial markers in optic chiasm. The present study indicates that pregabalin administration enhances myelin repair and ameliorates glial activation of optic chiasm following local injection of LPC.

[Some aspects of heart rate variability estimation in rats].

This study focuses on researching of heart rate variability (HRV) in rats with autoimmune myocarditis. Intact rats were investigated additionally. It was registered 2-, 5- and 20-min duration ECG from awake animals at rest-conditions and after cooling probe (CP), and then time domain and spectral parameters of HRV were calculated. We shown that 1) after CP decreasing of parasympathetic influence and augmentation of sympathetic influence on heart rate regulation in rats with autoimmune myocarditis was more manifested than in intact rats, 2) in CP with the 5-min ECG interval's duration was more informative for HRV estimation, 3) intracardiac inflammation leads to modification of correlation interconnection between some HRV-parameters, and that may talk about features of heart's chronotropic regulation in rats with autoimmune myocarditis.

Development of an improved animal model of experimental autoimmune myositis.

Multiple animal models of experimental autoimmune myositis (EAM) have been developed. However, these models vary greatly in the severity of disease and reproducibility. The goal of this study was to test whether vaccination twice with increased dose of rat myosin and pertussis toxin (PT) could induce EAM with severer disease in mice. BALB/c mice were injected with 1 mg rat myosin in 50% complete Freund's adjuvant (CFA) weekly for four times and one time of PT (EAM) or twice with 1.5 mg myosin in CFA and PT (M-EAM). In comparison with that in the CFA and PT injected controls, vaccination with rat myosin and injection PT significantly reduced the muscle strength and EMG duration, elevated serum creatine kinase levels, promoted inflammatory infiltration in the muscle tissues, leading to pathological changes in the muscle tissues, demonstrating to induce EAM. Interestingly, we found that vaccination twice with the high dose of myosin and PT prevented EAM-related gain in body weights and caused significantly less muscle strength in mice. More importantly, all of the mice receiving high dose of myosin and PT survived while 3 out of 16 mice with four times of low dose of myosin died. Finally, vaccination with high dose of myosin promoted CD4(+) and CD8(+) T cell infiltration in the muscle tissues and up-regulated MHC-I expression in the muscle tissues of mice. Hence, the new model of EAM is a time-saving, efficient and easily replicable tool for studying autoimmune myositis.

[Follow-up of nerve and muscle disorders: the collaboration between general practitioner and specialist]. / Suivi des malades neuromusculaires: collaboration entre praticien et spécialiste.

The follow-up of neuromuscular diseases varies widely as the etiologies and requires specialized care. Yet, the inter-disciplinary and collaborative approach with the General Practitioner (GP) is indispensable, and we may review the international recommandations according to the Evidence-based Medicine (EBM) of frequent symptoms like cramps and neuropathic pain. Besides, we discuss some principles of our daily pratice, which--we hope--would facilitate the communication with the GPs.

Functional redundancy of MyD88-dependent signaling pathways in a murine model of histidyl-transfer RNA synthetase-induced myositis.

We have previously shown that i.m. administration of bacterially expressed murine histidyl-tRNA synthetase (HRS) triggers florid muscle inflammation (relative to appropriate control proteins) in various congenic strains of mice. Because severe disease develops even in the absence of adaptive immune responses to HRS, we sought to identify innate immune signaling components contributing to our model of HRS-induced myositis. In vitro stimulation assays demonstrated HRS-mediated activation of HEK293 cells transfected with either TLR2 or TLR4, revealing an excitatory capacity exceeding that of other bacterially expressed fusion proteins. Corresponding to this apparent functional redundancy of TLR signaling pathways, HRS immunization of B6.TLR2(-/-) and B6.TLR4(-/-) single-knockout mice yielded significant lymphocytic infiltration of muscle tissue comparable to that produced in C57BL/6 wild-type mice. In contrast, concomitant elimination of TLR2 and TLR4 signaling in B6.TLR2(-/-).TLR4(-/-) double-knockout mice markedly reduced the severity of HRS-induced muscle inflammation. Complementary subfragment analysis demonstrated that aa 60-90 of HRS were absolutely required for in vitro as well as in vivo signaling via these MyD88-dependent TLR pathways--effects mediated, in part, through preferential binding of exogenous ligands capable of activating specific TLRs. Collectively, these experiments indicate that multiple MyD88-dependent signaling cascades contribute to this model of HRS-induced myositis, underscoring the antigenic versatility of HRS and confirming the importance of innate immunity in this system.

Wnt signaling in the pathogenesis of multiple sclerosis-associated chronic pain.

Many multiple sclerosis (MS) patients develop chronic pain, but the underlying pathological mechanism is unknown. Mice with experimental autoimmune encephalomyelitis (EAE) have been widely used to model MS-related neurological complications, including CNS demyelination, neuroinflammation and motor impairments. Similar to MS patients, EAE mice also develop chronic pain. We are interested in elucidating the potential involvement of Wnt signaling in the pathogenesis of chronic pain in EAE mice. In this study, we characterized the expression of Wnt signaling proteins in the spinal cord dorsal horn (SCDH) of EAE mice, by immunoblotting and immunostaining. The EAE model was created by immunization of adult mice (C57BL/6, 10 weeks) with myelin oligodendrocyte glycoprotein (MOG) 35-55. Robust mechanical hyperalgesia and allodynia were developed in both fore- and hindpaws of the EAE mice. Wnt3a, a prototypical Wnt ligand for the canonical pathway, was significantly increased in the SCDH of the EAE mice. Another key protein in the canonical pathway, ß-catenin, was also significantly up-regulated. In addition, Wnt5a, a prototypic Wnt ligand for the non-canonical pathway, and its receptor (co-receptor) Ror2 were also up-regulated in the SCDH of the EAE mice. We further found that Wnt5a antagonist Box5 and ß-catenin inhibitor indomethacin attenuated mechanical allodynia in the EAE mice. Our data collectively suggest that Wnt signaling pathways are up-regulated in the SCDH of the EAE mice and that aberrant activation of Wnt signaling contributes to the development of EAE-related chronic pain.

Axonal damage in multiple sclerosis.

Multiple sclerosis is a debilitating disease of the central nervous system that has been characteristically classified as an immune-mediated destruction of myelin, the protective coating on nerve fibers. Although the mechanisms responsible for the immune attack to central nervous system myelin have been the subject of intense investigation, more recent studies have focused on the neurodegenerative component, which is cause of clinical disability in young adults and appears to be only partially controlled by immunomodulatory therapies. Here, we review distinct, but not mutually exclusive, mechanisms of pathogenesis of axonal damage in multiple sclerosis patients that are either consequent to long-term demyelination or independent from it. We propose that the complexity of axonal degeneration and the heterogeneity of the underlying pathogenetic mechanisms should be taken into consideration for the design of targeted therapeutic intervention.

Eculizumab prevents anti-ganglioside antibody-mediated neuropathy in a murine model.

Anti-GQ1b ganglioside antibodies are the serological hallmark of the Miller Fisher syndrome (MFS) variant of the paralytic neuropathy, Guillain-Barré syndrome, and are believed to be the principal pathogenic mediators of the disease. In support of this, we previously showed in an in vitro mouse model of MFS that anti-GQ1b antibodies were able to bind and disrupt presynaptic motor nerve terminals at the neuromuscular junction (NMJ) as one of their target sites, thereby causing muscle paralysis. This injury only occurred through activation of complement, culminating in the formation and deposition of membrane attack complex (MAC, C5b-9) in nerve membranes. Since this step is crucial to the neuropathic process and an important convergence point for antibody and complement mediated membrane injury in general, it forms an attractive pharmacotherapeutic target. Here, we assessed the efficacy of the humanized monoclonal antibody eculizumab, which blocks the formation of human C5a and C5b-9, in preventing the immune-mediated motor neuropathy exemplified in this model. Eculizumab completely prevented electrophysiological and structural lesions at anti-GQ1b antibody pre-incubated NMJs in vitro when using normal human serum (NHS) as a complement source. In a novel in vivo mouse model of MFS generated through intraperitoneal injection of anti-GQ1b antibody and NHS, mice developed respiratory paralysis due to transmission block at diaphragm NMJs, resulting from anti-GQ1b antibody binding and complement activation. Intravenous injection of eculizumab effectively prevented respiratory paralysis and associated functional and morphological hallmarks of terminal motor neuropathy. We show that eculizumab protects against complement-mediated damage in murine MFS, providing the rationale for undertaking clinical trials in this disease and other antibody-mediated neuropathies in which complement activation is believed to be involved.

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist JWH-133 in a rodent model of autoimmune uveoretinitis.

Previous studies have shown that cannabinoids have anti-inflammatory and immune-modulating effects, but the precise mechanisms of action remain to be elucidated. In this study, we investigated the effect of JWH 133, a selective agonist for cannabinoid receptor 2, the main receptor expressed on immune cells, in a model of autoimmune disease, experimental autoimmune uveoretinitis (EAU). JWH 133 suppressed EAU in a dose-dependent manner (0.015-15 mg/kg), and the suppressive effect could be achieved in the disease-induction stage and the effector stage. Leukocytes from mice, which had been treated with JWH 133, had diminished responses to retinal peptide and mitogen Con A stimulation in vitro. In vivo JWH 133 treatment also abrogated leukocyte cytokine/chemokine production. Further in vitro studies indicated that JWH 133 down-regulated the TLR4 via Myd88 signal transduction, which may be responsible for its moderate, suppressive effect on antigen presentation. In vivo JWH 133 treatment (1 mg/kg) also suppressed leukocyte trafficking (rolling and infiltration) in inflamed retina as a result of an effect on reducing adhesion molecules CD162 (P-selectin glycoprotein ligand 1) and CD11a (LFA-1) expression on T cells. In conclusion, the cannabinoid agonist JWH 133 has a high in vivo, anti-inflammatory property and may exert its effect via inhibiting the activation and function of autoreactive T cells and preventing leukocyte trafficking into the inflamed tissue.

[Observation of auditory brainstem response and distortion product otoacoustic emission on the animal model of autoimmune auditory neuropathy].

OBJECTIVE: To set up an animal model of autoimmune auditory neuropathy and to observe the auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) in guinea pigs. METHODS: The spiral ganglion and the cochlear nerve were obtained and purified by electrophoresis from 250 normal guinea pigs. The purified cochlear nerve antigen was mixed with an equal volume of complete Freunds adjuvant for immunization. Seventy guinea pigs were divided into three groups: experiment group (50 guinea pigs), control group (10 guinea pigs), normal group (10 guinea pigs). ABR, DPOAE, serum IgG levels, and morphological changes of spiral ganglion cells and the cochlear nucleus were observed. The protein expressions of the antigen were examined by immunohistochemistry and the super-structure of the auditory nerve were observed. RESULTS: The threshold of ABR response increased ranged from 10 to 25 dB in 32% (32/100 ears) of the guinea pigs. The peak latencies of waves I , III and the interpeak latency I approximately III were prolonged in the hearing loss group of guinea pigs. Prolonged peak latency of wave III was noted in hearing loss group at 2 and 3 weeks post immunization and slowly decreased to normal peak latency. The amplitude of DPOAE was no difference in the guinea pigs. The levels of serum IgG increased significantly compared with those of the control group. Inflammatory cell infiltration was observed in the cochlear nerve and the number of spiral ganglion cells detected. On the contrary, inflammatory cell infiltration was not observed in the cochlear nucleus. The cell densities and the across-sectional areas of neurons in anteroventral cochlear nucleus and posteroventral cochlear nucleus were no difference in the guinea pigs. The antigen protein distributed strictly in cochlear nerve and the spiral ganglion. Some demyelinated areas in cochlear nerve was observed in this group. The threshold of ABR response in 68% guinea pigs (68/100 ears) did not increase. The data of DPOAE and the serum IgG levels show no difference compared with the control group. There were not pathological observation in spiral ganglion cells, cochlear nucleus and cochlear nerve. CONCLUSION: An animal model of autoimmune auditory neuropathy has been set up successfully and the character of the ABR and DPOAE was observed.

Involvement of CCR5 in the passage of Th1-type cells across the blood-retina barrier in experimental autoimmune uveitis.

Although the recruitment of T helper cell type 1 (Th1)/Th2 cells into peripheral tissues is essential for inflammation and the host response to infection, the traffic signals that enable the distinct positioning of Th1/Th2 cells are unclear. We have determined the role of CC chemokine receptor 5 (CCR5) in this using experimental autoimmune uveitis (EAU) as a model system. In EAU, Th1-like cells are preferentially recruited into the retina across the blood-retina barrier, partly as a result of expression of the adhesion molecules P-selectin glycoprotein ligand 1 and lymphocyte function-associated antigen-1 on these cells. CD3+ T cells, infiltrating the retina, also expressed the chemokine receptor CCR5, and CCR5 ligands, macrophage-inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated on activation, normal T expressed and secreted (RANTES), were strongly expressed in the retina at peak EAU. Th1-like cells, polarized in vitro, expressed high levels of CCR5. The trafficking of these CCR5+ cells was examined by tracking them after adoptive transfer in real time in vivo at an early disease stage using scanning laser ophthalmoscopy. Treatment of the cells with antibody against CCR5 prior to transfer resulted in a reduction in their infiltration into the retina. However, rolling velocity, rolling efficiency, and adherence of the cells to retinal endothelium were not reduced. CCR5 is clearly important for Th1 cell recruitment, and this study demonstrates for the first time in vivo that CCR5 may act at the level of transendothelial migration rather than at the earlier stage of rolling on the endothelium.

[Mechanisms of transition from acute to chronic muscle pain]. / Mechanismen der Chronifizierung von Muskelschmerz.

The present article presents an overview of neurophysiological and neuroanatomical mechanisms that may be involved in the transition from acute to chronic muscle pain. The report is based on data that were obtained in studies on anaesthetised rats in which an acute or chronic myositis was induced experimentally. The inflamed muscle tissue was evaluated using histochemical and immunohistochemical methods, and the impulse activity of single muscle nociceptors or dorsal horn neurones was recorded in electrophysiological experiments in vivo. Chronic myositis was associated with a higher innervation density of the tissue with putative nociceptive free nerve endings that contain the neuropeptide substance P (SP). The nociceptive information from muscle to the spinal cord was largely carried by unmyelinated fibres with tetrodotoxin-resistant Na(+)-channels. At the spinal level, myositis caused changes in the connectivity of dorsal horn neurones which were reflected in an expansion of the input (target) region of the muscle nerve. The central sensitisation can explain the hyperalgesia and spread of pain in patients. Chronic spontaneous muscle pain, however, appears to be due to a lack of NO. The final step in the transition from acute to chronic pain involves structural changes that perpetuate the functional changes. In rat experiments employing nerve lesions or muscle inflammation, such morphological changes become apparent within a few hours after the lesion.

Pertussis toxin alters the innate and the adaptive immune responses in a pertussis-dependent model of autoimmunity.

Pertussis toxin (PTX) is used to promote development of autoimmune diseases. The mechanism(s) are still incompletely understood. We dissected the innate and adaptive immune responses in a PTX-dependent model of autoimmune retinal disease, experimental autoimmune uveoretinitis (EAU), a Th1-driven disease of the neural retina elicited in F344 rats with a peptide derived from the retinal antigen interphotoreceptor retinoid binding protein (IRBP). Our results showed that optimal doses of PTX led to strongly increased innate cytokine responses, followed by enhanced adaptive Th1 immunity and disease. At supraoptimal doses of PTX, EAU was suppressed, the animals exhibited persistent lymphocytosis and had an inhibited chemotactic response to chemokines. We suggest that the suppressive effect of PTX at supraoptimal doses is due to inhibition of lymphocyte emigration from the blood into the target tissue, secondary to inhibition of Gi-protein-coupled chemokine receptor signaling, that persists into the effector phase of disease.

Neurological and neuroendocrine-cytokine inter-relationship in the antiphospholipid syndrome.

Although many neurological deficits have been described in the antiphospholipid syndrome (APS), only stroke is well established and accepted as a diagnostic criterion in the disease. We presently review clinical data obtained from large series of cases regarding stroke, dementia, epilepsy, chorea, migraine, white-matter disease, and behavioral changes in APS, or linked-to-laboratory criteria such as antiphospholipid antibodies (aPL). The contribution of animal models to our understanding of these manifestations of APS is stressed, especially regarding the cognitive and behavioral aspects for which we have established model systems in the mouse. These models utilize immunization of mice with beta(2)-glycoprotein1, a central autoantigen in APS, which induces persistent high levels of aPLs. These mice develop hyperactive behavior after a period of four months, as well as deficits in learning and memory, and are potentially valuable as a system in which to study the pathogenesis and treatment of cognitive and behavioral aspects of APS. We have developed another model, in which IgGs from APS patients induce depolarization of brain synaptoneurosomes, and which may serve as a model for the pathogenesis of epilepsy in APS. Hormonal changes are another potential CNS manifestation of APS and this may be potentially linked to the systemic and central effects of cytokines such as interleukin-3. Better understanding of the link between APS and neurological or neuroendocrine manifestations other than stroke will reveal whether they can be used as clinical criteria for the diagnosis of APS and, it is hoped, lead to better treatment.

Experimental autoimmune myositis in the lewis rat: lack of spontaneous T-cell apoptosis and therapeutic response to glucocorticosteroid application.

Recently, it has been shown that inflammatory T-cells in human idiopathic myositis only very rarely undergo spontaneous apoptosis. The animal model of experimental autoimmune myositis (EAM) in the Lewis rat was chosen to investigate whether similar findings hold true in rat muscle and if glucocorticosteroids act by induction of T-cell apoptosis in inflammatory lesions. The rate of spontaneous T-cell apoptosis in rat EAM was low, even in muscle specimens with extensive inflammation. After intravenous glucocorticosteroid pulse therapy we found a dramatic increase in the rate of apoptotic T-cells in the inflamed muscles. Up to 50% of these apoptotic T-cells were CD8 positive apoptotic T-cells. T-cell apoptosis was significantly lower in similarly inflamed muscle specimens of the control group. We suggest that glucocorticosteroids induce apoptosis of endomysial T-cells in human idiopathic polymyositis. Glucocorticosteroid-induced apoptosis may be a candidate mechanism in the termination of inflammatory activity.