Keiichi Himuro

Serum cytokine and chemokine profiles in patients with myasthenia gravis

Myasthenia gravis (MG) is an autoimmune‐mediated inflammatory disease of the neuromuscular junction. Previous studies of animal MG models have suggested important roles of cytokines in MG pathogenesis, but adequate studies on cytokines in human MG are lacking. Using a multiplex suspension array system, we measured the serum levels of 27 cytokines/chemokines in 47 anti‐acetylcholine receptor antibody‐positive patients with MG and 20 normal controls (NC) to investigate the contribution of cytokines/chemokines toward MG pathogenesis. Correlations between clinical parameters and cytokine/chemokine levels in patients with MG were also examined. The serum levels of interleukin (IL)‐15 (mean ± standard deviation: 6·85 ± 6·97 pg/ml) and vascular endothelial growth factor (VEGF) (96·21 ± 71·60 pg/ml) significantly increased, whereas IL‐4 levels (3·57 ± 0·86 pg/ml) decreased in patients with MG compared with NC (IL‐15: 4·42 ± 1·55 pg/ml; VEGF: 63·51 ± 32·95 pg/ml; IL‐4: 4·15 ± 0·81 pg/ml, P < 0·05). In addition, eight cytokines (IL‐4, IL‐8, IL‐15, eotaxin, macrophage inflammatory protein‐1α, macrophage inflammatory protein‐1β, VEGF and IL‐1b) were significantly changed among MG patients with thymoma, MG patients without thymoma and NC (P < 0·05). Some cytokines, such as IL‐4, IL‐15, and VEGF, may play roles in the pathogenesis of MG.

First adult case of Helicobacter cinaedi meningitis

Helicobacter cinaedi, a gram-negative spiral bacillus that inhabits the intestinal tracts of rodents and primates, is associated with gastroenteritis in humans. H. cinaedi infection has been commonly reported in immunocompromised individuals such as human immunodeficiency virus-infected patients, but rarely in immunocompetent individuals. Prior contact with animals has attracted attention as a possible source of H. cinaedi infection. We report a case of meningitis in an immunocompetent 34-year-old woman who had daily contact with a kitten for a month. She developed acute headaches, fevers, and chills. Neurological examination revealed neck stiffness and her cerebrospinal fluid (CSF) exhibited polymorphonuclear pleocytosis and a decreased concentration of glucose. Blood and CSF cultures were negative; however, the pathogen responsible for her condition was identified as H. cinaedi by polymerase chain reaction in CSF. This is the first adult case of meningitis caused by H. cinaedi. Thus, this bacillus should be considered a possible causative agent of bacterial meningitis in healthy adults.

HLA-DRB1*14 and DQB1*05 are associated with Japanese anti-MuSK antibody-positive myasthenia gravis patients

BACKGROUND Myasthenia gravis (MG) is an autoimmune disorder presumed to be associated with genetic susceptibility. This study aims to determine whether HLA is associated with MG in Japanese patients. METHODS We included 58 MG patients with anti-acetylcholine receptor antibody (AChR+MG) and 14 MG patients with muscle-specific receptor tyrosine kinase (MuSK+MG) and determined HLA-A, B, DRB1 and -DQB1 alleles using polymerase chain reaction with sequence-specific oligonucleotide and primers. AChR+MG was classified into the three subgroups: early-onset MG (EOMG; n=11), late-onset MG (LOMG; n=20), and thymoma-associated MG (n=27). Healthy volunteers (n=100) served as controls. RESULTS A significant positive association was observed between MuSK+MG with the DRB1*14 [57.1%, MuSK+MG vs. 18.0%, healthy controls (HC); odds ratio (OR): 6.1] and DQB1*05 [78.6%, MuSK+MG vs. 30.0%, HC; odds ratio (OR): 8.5]. We found a negative association between LOMG and DQB1*04 [5.0%, LOMG vs. 37.0%, HC; OR: 0.09]. There was no association between other MG subgroups and HLA alleles. CONCLUSION HLA-DRB1*14 and DQB1*05 were associated with MuSK+MG, therefore these alleles may play important roles in developing MuSK+MG across the races.

Changes in inflammatory cytokine networks in myasthenia gravis

Myasthenia gravis (MG) is an autoimmunological inflammatory disorder of the neuromuscular junction. Inflammation could be a key player for understanding the pathogenesis of MG. We measured the serum levels of 24 inflammatory cytokines in 43 patients with anti-acetylcholine receptor antibody-positive MG and 25 healthy controls. In patients with MG, serum levels of a proliferation-inducing ligand (APRIL), IL-19, IL-20, IL-28A and IL-35 were significantly increased as compared with controls (p < 0.05). Among them, IL-20, IL-28A and IL-35 were significantly decreased after treatment (p < 0.05). In clinical subtype analyses, APRIL and IL-20 were increased in patients with late-onset MG and IL-28A levels were increased in patients with thymoma-associated MG compared with healthy controls (p < 0.01). The results of the present study demonstrate both anti-inflammatory and inflammatory cytokines are upregulated in MG, reflecting the importance of cytokine-mediated inflammation and its regulation in MG pathophysiology.

Serum high mobility group box 1 is upregulated in myasthenia gravis

Objective High mobility group box 1 (HMGB1) functions as an inflammatory mediator and is implicated in the pathogenesis of various autoimmune diseases. Our primary aim is to determine whether HMGB1 is involved in the pathogenesis of myasthenia gravis (MG). Methods Serum HMGB1 levels of 60 patients with anti-acetylcholine receptor (AChR) antibody-positive MG without immunosuppressive treatment and of 10 patients with anti-muscle-specific receptor tyrosine kinase (MuSK) antibody-positive MG were compared with those in 40 controls. We also investigated the potential correlation between serum HMGB1 levels and the clinical variables in patients with MG. Results Serum HMGB1 levels in patients with anti-AChR antibody-positive MG were higher than those in controls (7.80±7.47 vs 4.13±2.55 ng/mL, p=0.004) and were decreased after treatment (p=0.051). Although not significant, patients with anti-MuSK antibody-positive MG showed higher serum HMGB1 levels than the controls (p=0.178). There were correlations between serum HMGB1 levels and phenotypes of anti-AChR antibody-positive MG: patients with generalised MG showed higher HMGB1 levels than those of patients with ocular MG (p=0.059) and controls (p=0.002); patients with thymoma showed higher HMGB1 levels than those without thymoma (p=0.094) and controls (p=0.001). Conclusions Serum HMGB1 is elevated in patients with MG and may play a key role in the inflammation of the neuromuscular junction.

Increased serum peroxiredoxin 5 levels in myasthenia gravis.

Extracellular peroxiredoxin 5 (PRX5) is known to be an inflammatory mediator. The serum PRX5 levels of 40 patients with anti-acetylcholine receptor antibody-positive MG and those of 40 controls were measured. PRX5 levels in patients with MG were higher than those in the controls (P=0.045). Thymoma-associated MG patients showed higher PRX5 levels than late-onset MG patients and controls (P<0.05). There were significant associations between the serum PRX5 levels and high mobility group box 1 levels. PRX5 elevation in MG could be related to the neuromuscular junction breakdown and plays a pivotal role in the pathogenic inflammation of MG.

Spinal myoclonus in the periscapular muscles after mastectomy assessed by FDG-PET

We describe a 64-year-old woman who developed spinal myoclonus around the left scapula after long thoracic nerve injury by mastectomy. Involuntary muscle twitching was semi-rhythmic, and ultrasonography identified contraction of the serratus anterior, teres major, and rhomboid muscles. FDG-PET imaging revealed markedly increased glucose uptake only in the serratus anterior. Lidocaine injection into this muscle resulted in complete cessation of the involuntary movement, and then she was successfully treated with botulinum toxin type A. These findings raise the possibility that the myoclonus was primarily caused by ectopic firing of the injured long thoracic nerve, then spreading to adjacent muscles possibly via a central mechanism mediated by group Ia afferents. The new imaging tools, such as FDG-PET and ultrasonography, were useful to determine the therapeutic target muscle.

Adequate tacrolimus concentration for myasthenia gravis treatment

A single, oral dose of 3 mg/day tacrolimus, approved for myasthenia gravis (MG) treatment in Japan, was shown to reduce steroid dose and anti‐acetylcholine receptor (AChR) antibody titers as well as to improve MG symptoms. However, no studies have investigated the association between tacrolimus concentration and its clinical efficacy in MG. In this study, we aimed to determine the optimal tacrolimus concentration for MG treatment.

Predictive score for oral corticosteroid-induced initial worsening of seropositive generalized myasthenia gravis

BACKGROUND Initial worsening of symptoms after the start of corticosteroid administration is a major concern in the treatment of myasthenia gravis (MG). However, the risk factors or specific patient backgrounds related to this issue have not been fully understood. We aimed to determine the risk factors and developed a scoring system for predicting initial worsening in generalized MG. METHODS We enrolled 62 generalized MG patients with anti-acetylcholine receptor antibody. Initial worsening was defined as an increment of three points in the Quantitative MG score within 2 weeks after the start of steroid treatment. A multivariate logistic regression model was used to determine the risk factors, and predictive scores were assigned. Bootstrap resampling was applied to evaluate the risk score models internal validity. RESULTS Steroid-induced initial worsening occurred in 26% of MG patients and was correlated with thymoma-associated or early-onset MG (p = 0.018), initial prednisolone doses ≥40 mg/day (p = 0.029), and upper limb weakness (p = 0.039). Stepwise multivariate logistic regression identified these three clinical factors for predicting initial worsening in MG. A predictive score of 0-3 points had a bootstrapping area under the curve of 0.770 (0.625-0.878). CONCLUSIONS Our scoring system based on three clinical characteristics can predict the likelihood of steroid-induced initial worsening in MG.

Polymorphisms of CYP3A5 Affect Serum Levels and Maintenance Doses of Tacrolimus in Myasthenia Gravis Patients

Objectives: To evaluate the influences of polymorphisms of cytochrome P450 (CYP) 3A5 (A6986G, CYP3A5*3) on serum levels of tacrolimus and cyclosporine (CyA) in patients with myasthenia gravis (MG). Methods: This study included 74 MG patients treated with tacrolimus (n=65) or CyA (n=22). Genomic DNA was extracted and amplified with specific primers, and CYP3A5 alleles were confirmed by direct sequencing of PCR products on an automated AB13100 DNA sequencer. We measured blood trough level (C0) of tacrolimus and CyA. Clinical disabilities were evaluated with the MG-ADL scale. Results: For tacrolimus C0, the CYP3A5*3/*3 genotype was associated with higher levels than the CYP3A5*1/*3 genotypes (7.1 ng/ml versus 2.9 ng/ml; P<0.0001) and CYP3A*1/*1 (7.1 ng/ml versus 1.3 ng/ml; P<0.0004). The improvement in the mean MG-ADL scores tended to be better in MG patients with the CYP3A5*3/*3 or CYP3A5*1/*3 than those with CYP3A5*1/*1. For the CyA concentrations, CYP3A5 genotypes did not have significant effects. Conclusion: In MG patients, CYP3A5 polymorphism significantly affects serum levels of tacrolimus and thereby treatment effects, but not those of CyA. The maintenance dose of tacrolimus should be determined considering CYP3A5 polymorphism.