Biomedical subjects

Michiaki Koga

Publications and source records attributed to Michiaki Koga.

At least 19 recordsLinked to original sources

PubMed2007

Anti-gp210 and anti-centromere antibodies are different risk factors for the progression of primary biliary cirrhosis.

UNLABELLED: The predictive role of antinuclear antibodies (ANAs) remains elusive in the long-term outcome of primary biliary cirrhosis (PBC). The progression of PBC was evaluated in association with ANAs using stepwise Cox proportional hazard regression and an unconditional stepwise logistic regression model based on the data of 276 biopsy-proven, definite PBC patients who have been registered to the National Hospital Organization Study Group for Liver Disease in Japan (NHOSLJ). When death of hepatic failure/liver transplantation (LT) was defined as an end-point, positive anti-gp210 antibodies (Hazard ratio (HR) = 6.742, 95% confidence interval (CI): 2.408, 18.877), the late stage (Scheuer's stage 3, 4) (HR = 4.285, 95% CI:1.682,10.913) and male sex (HR = 3.266, 95% CI: 1.321,8.075) were significant risk factors at the time of initial liver biopsy. When clinical progression to death of hepatic failure/LT (i.e., hepatic failure type progression) or to the development of esophageal varices or hepatocellular carcinoma without developing jaundice (Total bilirubin < 1.5 mg/dL) (i.e., portal hypertension type progression) was defined as an end-point in the early stage (Scheuer's stage 1, 2) PBC patients, positive anti-gp210 antibodies was a significant risk factor for hepatic failure type progression [odds ratio (OR) = 33.777, 95% CI: 5.930, 636.745], whereas positive anti-centromere antibodies was a significant risk factor for portal hypertension type progression (OR = 4.202, 95% CI: 1.307, 14.763). Histologically, positive anti-gp210 antibodies was most significantly associated with more severe interface hepatitis and lobular inflammation, whereas positive anticentromere antibodies was most significantly associated with more severe ductular reaction. CONCLUSION: These results indicate 2 different progression types in PBC, hepatic failure type and portal hypertension type progression, which may be represented by positive-anti-gp210 and positive-anticentromere antibodies, respectively.

Adult↗

PubMed2006

Ganglioside-specific IgG and IgA recruit leukocyte effector functions in Guillain-Barré syndrome.

The capacity of ganglioside-specific autoantibodies to recruit leukocyte effector functions was studied. Serum samples from 87 patients with Guillain-Barré (GBS) or Miller Fisher syndrome (MFS), containing GM1-, GQ1b-, or GD1b-specific IgG or IgA, were tested for leukocyte activating capacity. Ganglioside-specific IgG antibodies generally induced leukocyte activation, irrespective of specificity. The magnitude of leukocyte degranulation correlated with GM1- and GQ1b-specific IgG titers, but not with disease severity. Finally, GM1-specific IgA activated leukocytes through the IgA receptor, FcalphaRI (CD89). Therefore, both ganglioside-specific IgG and IgA can recruit leukocyte effector functions, which may be relevant in the pathogenesis of GBS and MFS.

Adolescent↗

PubMed2006

Campylobacter coli enteritis and Guillain-Barré syndrome: no evidence of molecular mimicry and serological relationship.

Campylobacter coli was isolated from two Guillain-Barré syndrome (GBS) patients who had anti-GM1 and anti-GD1 IgG antibodies. Although both this bacteria and Campylobacter jejuni are common causes of diarrheal illness, previous studies have focused only on C. jejuni as the causal agent of GBS. To determine whether C. coli also is a causative agent, we examined the hypothesis that production of anti-ganglioside antibodies is induced by ganglioside-mimics on that bacterial lipo-oligosaccharide (LOS), as in C. jejuni-associated GBS. LOSs of both C. coli isolates had very weak reactivities with anti-GM1 and anti-GD1a IgG monoclonal antibodies, whereas those of some GBS-related C. jejuni isolates had strong reactivities. Anti-GM1 and anti-GD1a IgG antibodies from the two patients were not absorbed as much by the LOSs of their isolates as were those of GBS-related C. jejuni strains. These findings do not support the hypothesis of ganglioside mimicry on C. coli isolates' LOSs. We next made a serological assay of recent C. coli infection in 74 patients with GBS, 26 with Fisher syndrome (FS), 49 with other neurological diseases (OND), and 37 normal controls (NC) using the bacterial outer membrane protein as antigen. Eight (11%) GBS and two (8%) FS patients had two or three classes of IgG, IgM, and IgA anti-C. coli antibodies. Anti-C. jejuni IgG and IgA antibody titers were significantly higher than those of anti-C. coli (respectively, p = 0.03 and 0.01). This suggests that anti-C. coli antibodies cross-react with C. jejuni protein. We concluded that a C. coli infection was not the cause of GBS in our patients. Both isolation of a microorganism from, and the positive infectious serology of, GBS patients do not always indicate the causal agent.

Adult↗

PubMed2006

Identification of a sialate O-acetyltransferase from Campylobacter jejuni: demonstration of direct transfer to the C-9 position of terminalalpha-2, 8-linked sialic acid.

We have identified a sialate O-acetyltransferase in the lipo-oligosaccharide biosynthesis locus of Campylobacter jejuni. Strains possessing this locus are known to produce sialylated outer core structures that mimic host gangliosides, and have been implicated in triggering the onset of Guillain-Barré syndrome. The acetyltransferase, which was cloned and expressed as a fusion construct in Escherichia coli, is soluble and homologous with members of the NodL-LacA-CysE family of O-acetyltransferases. This enzyme catalyzes the transfer of O-acetyl groups onto oligosaccharide-bound sialic acid, with a high specificity for terminal alpha2,8-linked residues. The modification is directed to C-9 and not C-7 as is believed to occur more commonly in other organisms. Despite their wide prevalence and importance in both eukaryotes and prokaryotes, this is the first report to describe the characterization of a purified sialate O-acetyltransferase.

Acetyltransferases↗

PubMed2006

Comprehensive analysis of bacterial risk factors for the development of Guillain-Barre syndrome after Campylobacter jejuni enteritis.

BACKGROUND: Guillain-Barre syndrome (GBS), a postinfectious autoimmune-mediated neuropathy, is a serious complication after Campylobacter jejuni enteritis. METHODS: To investigate the bacterial risk factors for developing GBS, genotypes, serotypes, and ganglioside mimics on lipo-oligosaccharide (LOS) were analyzed in C. jejuni strains from Japanese patients. RESULTS: Strains from patients with GBS had LOS biosynthesis locus class A more frequently (72/106; 68%) than did strains from patients with enteritis (17/103; 17%). Class A strains predominantly were serotype HS:19 and had the cstII (Thr51) genotype; the latter is responsible for biosynthesis of GM1-like and GD1a-like LOSs. Both anti-GM1 and anti-GD1a monoclonal antibodies regularly bound to class A LOSs, whereas no or either antibody bound to other LOS locus classes. Mass-spectrometric analysis showed that a class A strain carried GD1a-like LOS as well as GM1-like LOS. Logistic regression analysis showed that serotype HS:19 and the class A locus were predictive of the development of GBS. CONCLUSIONS: The high frequency of the class A locus in GBS-associated strains, which was recently reported in Europe, provides the first GBS-related C. jejuni characteristic that is common to strains from Asia and Europe. The class A locus and serotype HS:19 seem to be linked to cstII polymorphism, resulting in promotion of both GM1-like and GD1a-like structure synthesis on LOS and, consequently, an increase in the risk of producing antiganglioside autoantibodies and developing GBS.

Antibodies, Bacterial↗

PubMed2006

Bacterial infections in Guillain-Barré and Fisher syndromes.

PURPOSE OF REVIEW: Progress has been made in our understanding of Guillain-Barré syndrome, especially in identifying the Campylobacter jejuni genes responsible for the development of clinical features. RECENT FINDINGS: C. jejuni is grouped into several classes based on the organization of lipo-oligosaccharide biosynthesis genes. A specific class carrying a sialyltransferase gene (cst-II) is associated with the development of Guillain-Barré syndrome, which is essential for the biosynthesis of ganglioside-like lipo-oligosaccharides. The class of C. jejuni expressed both GM1-like and GD1a-like lipo-oligosaccharides, which could induce the production of autoantibodies to GM1, to GD1a or to the GM1/GD1a complex, possibly increasing the risk of development. C. jejuni sialyltransferase (Cst-II) consists of 291 amino acids, and the 51st amino acid determines its enzymatic activity. Strains with cst-II (Thr51) expressed GM1-like or GD1a-like lipo-oligosaccharide whereas strains with cst-II (Asn51) expressed GT1a-like or GD1c-like lipo-oligosaccharide. Patients infected with the cst-II (Thr51) strains had anti-GM1 or anti-GD1a IgG antibodies, and showed limb weakness. Patients infected with the cst-II (Asn51) strains had anti-GQ1b IgG antibodies, and showed ophthalmoplegia and ataxia. SUMMARY: The cst-II gene is responsible for the development of Guillain-Barré and Fisher syndromes, and the polymorphism (Thr/Asn51) determines which syndrome develops after C. jejuni enteritis.

Animals↗

PubMed2006

[Development of testing kits of anti-ganglioside antibody: clinical utility in Guillain-Barré and Fisher syndromes].

We developed testing kits for anti-GM1 and anti-GQ1b IgG antibodies and examined their utilities in supporting the diagnosis of Guillain-Barré syndrome (GBS) and Fisher syndrome (FS). Anti-GM1 antibody was detected in 49% of 95 patients with GBS and in 5% or less of disease and normal controls. Anti-GQ1b antibody was detected in 85% of 55 patients with FS, whereas in none of the controls. Eight GBS patients, in whom anti-GM1 IgG antibody was judged negative using the kit, were found to have other anti-ganglioside IgG antibodies. Four of them showed ophthalmoplegia and had anti-GQ1b IgG antibody. Detection of anti-GM1 IgG antibody in GBS and of anti-GQ1b IgG antibody in FS within one week after the disease onset were significantly more frequent compared to albuminocytologic dissociation in the cerebrospinal fluids (GBS, 58% vs 32%; FS, 89% vs 20%). These findings indicate that our testing kits are useful for supporting the early diagnosis of GBS and FS.

Adult↗

PubMed2005

An adolescent with pharyngeal-cervical-brachial variant of Guillain-Barré syndrome after cytomegalovirus infection.

A 15-year-old Japanese girl developed bulbar palsy and upper limb-dominant muscle weakness 2 weeks after the onset of an upper respiratory tract infection due to cytomegalovirus (CMV). Her symptoms resembled that seen in the pharyngeal-cervical-brachial variant (PCB) of Guillain-Barré syndrome (GBS). Although bulbar palsy usually continues for several months in PCB, her bulbar palsy was very mild and improved rapidly before intravenous immunoglobulin therapy was instituted. Serum anti-GT1a IgG antibody titer was elevated at the acute phase of the disease and gradually decreased. The bulbar palsy-dominant GBS is thought to relate to anti-GT1a antibody and Campylobacter jejuni infection in adult patients. Our Case report suggests that CMV can also induce the production of anti-GT1a antibody, thereby resulting in PCB. When one sees acute onset bulbar palsy and limb muscle weakness, the possibility of PCB, even in children, should be considered, thus compelling the need for serum anti-ganglioside antibody measurement.

Adolescent↗

PubMed2005

Immunoglobulin KM allotypes are associated with the prevalence of autoantibodies to GD1a ganglioside, but not with susceptibility to the disease, in Japanese patients with Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS), an autoimmune disease of the peripheral nervous system, is associated with antecedent Campylobacter jejuni infection. GM and KM allotypes--genetic markers of immunoglobulin gamma and kappa chains, respectively--are implicated in the etiopathogenesis of several autoimmune diseases. To determine if GM/KM phenotypes are associated with GBS and influence antibody responses to C. jejuni and to GM1 and GD1a gangliosides, 72 Japanese GBS patients and 73 controls were allotyped for several GM and KM markers. Sera from patients were characterized for antibodies to C. jejuni, GM1, and GD1a. The distribution of KM phenotypes was significantly different in patients with anti-GD1a ganglioside antibodies from those who lacked these antibodies (P=0.029). No other significant associations were found. These results suggest that KM allotypes are not risk factors for developing GBS, but contribute significantly to the generation of autoimmune responses to GD1a ganglioside in patients with this disease.

Campylobacter Infections↗

PubMed2005

Electrophoresis-assisted open-tubular liquid chromatography/mass spectrometry for the analysis of lipooligosaccharide expressed by Campylobacter jejuni.

Lipooligosaccharide (LOS) is the major component of the external membrane of Campylobacter jejuni. LOS contains a hydrophobic moiety, lipid A, and a hydrophilic moiety, oligosaccharide. Due to the unique mimicry of human ganglioside structures and potential involvement in the induction of the autoimmune polyneuropathies, Guillain-Barré and Miller Fisher syndromes, the structural characterization of C. jejuni LOS has received much attention. We have been using capillary zone electrophoresis-mass spectrometry to analyze O-deacylated LOS from C. jejuni. In an attempt to optimize the separation conditions, the effect of methanol on the separation of LOS was investigated. It was found that methanol resulted in stronger adsorption of LOS onto the wall of fused-silica capillary. In this paper, we applied this adsorption to perform electrophoresis-assisted open-tubular liquid chromatography electrospray mass spectrometry for the analysis of O-deacylated LOS mixtures from C. jejuni. The analytical potential of the proposed strategy for the analysis of O-deacylated LOS glycoforms from five bacterial colonies is demonstrated. Online tandem mass spectrometry is shown to provide a powerful tool for characterization of variations in the hexosamine backbone, phosphorylation of the lipid A, and sialic acid sequence information.

Campylobacter jejuni↗

PubMed2005

Antibody titer to gp210-C terminal peptide as a clinical parameter for monitoring primary biliary cirrhosis.

BACKGROUND/AIMS: The presence of antibodies to the 210-kDa glycoprotein of the nuclear pore complex (gp210) is highly indicative of primary biliary cirrhosis (PBC). However, the significance of anti-gp210 antibody titers for monitoring PBC remains unresolved. METHODS: We used an ELISA with a gp210 C-terminal peptide as an antigen to assess serum antibody titers in 71 patients with PBC. RESULTS: Patients were classified into three groups: Group A in whom anti-gp210 titers were sustained at a high level, Group B in whom anti-gp210 status changed from positive to negative under ursodeoxycholic acid (UDCA) therapy, Group C in whom anti-gp210 antibodies were negative at the time of diagnosis. The rate of progression to end-stage hepatic failure was significantly higher in group A (60%) as compared to groups B (0%) and C (4.2%). The sustained antibody response to gp210 was closely associated with the severity of interface hepatitis. The significance of anti-gp210 antibody was confirmed by National Hospital Organization Study Group for Liver Disease in Japan. CONCLUSIONS: The serial quantitation of serum anti-gp210-C-terminal peptide antibodies is useful for monitoring the effect of UDCA and for the early identification of patients at high risk for end-stage hepatic failure.

Antibodies↗

PubMed2005

Epidemiology of Campylobacter jejuni isolated from patients with Guillain-Barré and Fisher syndromes in Japan.

Campylobacter jejuni isolation is the standard for the diagnosis of this type of bacterial infection, but there have been no epidemiological studies of a large number of C. jejuni isolates from patients with Guillain-Barre syndrome (GBS) and Fisher syndrome (FS). For 13 years, stool specimens from GBS/FS patients have been sent from 378 hospitals throughout Japan to the Tokyo Metropolitan Institute of Public Health. A total of 113 strains (11%) were isolated from the stool specimens from 1,049 patients. The isolation rate did not differ by region. The rates were 22% for 449 patients with a history of diarrhea and 2% for the others. An additional 18 isolates were provided by various hospitals. There was no noticeable seasonal distribution in the onset of C. jejuni isolated from patients with GBS/FS. The male/female ratios were 1.7:1 for GBS and 2.2:1 for FS. The patient age range showed a peak in 10- to 30-year-old subjects who had GBS and in 10- to 20-year-old subjects who had FS. The predominance of young adults and male patients who had C. jejuni-associated GBS/FS may be related to the preponderance of young adults and male patients who had C. jejuni enteritis. The median interval from diarrhea onset to neurologic symptom onset was 10 days for GBS/FS. Penner's C. jejuni serotype HS:19 was more frequently present in GBS (67%) than in enteritis (6%) patients. HS:2 was more frequent in FS (41%) than in enteritis (14%) patients. These findings suggest that certain C. jejuni strains specifically trigger GBS and that others specifically trigger FS.

Adolescent↗

PubMed2005

[Clinical features and treatment of Fisher syndrome].

To clarify the clinical features of patients with Fisher syndrome, we reviewed detailed clinical profiles and laboratory findings in 267 cases. The men:women ratio was about 3:2, median age at onset 42 years, and the two peaks were 30-39 and 50-59. Sixty two percent of the patients had an antecedent illness with upper respiratory infectious symptoms. As initial symptoms, 63% had diplopia, 33% ataxic gait, and 17% dysesthesia of the upper and/or lower limbs. Besides ophthalmoplegia, ataxia, and areflexia, blepharoptosis (42%), internal ophthalmoplegia (35%), facial palsy (25%), and bulbar palsy (16%) were present. Limb weakness was significant in 25% and sensory impairment in 52%. CSF albuminocytological dissociation was present in 80% after the second week. Most patients were given intravenous immunoglobulin (59%). None died, and almost all had a monophasic remitting course and a generally good outcome.

Adult↗

PubMed2004

Various immunization protocols for an acute motor axonal neuropathy rabbit model compared.

Various ganglioside immunization protocols were examined to refine the procedure for establishing an animal model of acute motor axonal neuropathy. The most effective was subcutaneous injection of an emulsion of 2.5mg of bovine brain ganglioside mixtures, keyhole lympet hemocyanin, and complete Freund's adjuvant to Japanese white rabbits, repeated at 3-week intervals. Under that protocol, all the rabbits developed marked flaccid paralysis associated with plasma anti-GM1 IgG antibody. This acute motor axonal neuropathy rabbit model also could be reproduced by the use of incomplete Freund's adjuvant, methylated bovine serum albumin, and New Zealand white rabbits. These results provide useful information for the confirmation of and further research on the model.

Acute Disease↗

PubMed2004

Carbohydrate mimicry between human ganglioside GM1 and Campylobacter jejuni lipooligosaccharide causes Guillain-Barre syndrome.

Molecular mimicry between microbial and self-components is postulated as the mechanism that accounts for the antigen and tissue specificity of immune responses in postinfectious autoimmune diseases. Little direct evidence exists, and research in this area has focused principally on T cell-mediated, antipeptide responses, rather than on humoral responses to carbohydrate structures. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, occurs 1-2 wk after various infections, in particular, Campylobacter jejuni enteritis. Carbohydrate mimicry [Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-] between the bacterial lipooligosaccharide and human GM1 ganglioside is seen as having relevance to the pathogenesis of Guillain-Barré syndrome, and conclusive evidence is reported here. On sensitization with C. jejuni lipooligosaccharide, rabbits developed anti-GM1 IgG antibody and flaccid limb weakness. Paralyzed rabbits had pathological changes in their peripheral nerves identical with those present in Guillain-Barré syndrome. Immunization of mice with the lipooligosaccharide generated a mAb that reacted with GM1 and bound to human peripheral nerves. The mAb and anti-GM1 IgG from patients with Guillain-Barré syndrome did not induce paralysis but blocked muscle action potentials in a muscle-spinal cord coculture, indicating that anti-GM1 antibody can cause muscle weakness. These findings show that carbohydrate mimicry is an important cause of autoimmune neuropathy.

Animals↗

PubMed2004

Clinical correlates of serum anti-GT1a IgG antibodies.

Patients with the pharyngeal-cervical-brachial variant (PCB) of Guillain-Barré syndrome (GBS) have anti-GT1a IgG with or without GQ1b reactivity, whereas those with Fisher syndrome (FS) or Bickerstaff's brainstem encephalitis (BBE) have anti-GQ1b IgG antibodies which cross-react with GT1a. The nosological relationship between these conditions has yet to be established. To investigate the relationships between each manifestation and between clinical features and the coexistence of anti-GQ1b IgG, we reviewed neurological signs present during illnesses of 140 patients who had anti-GT1a IgG. Based on our criteria, FS was diagnosed for 64 (46%) patients, GBS for 22 (16%), BBE for 14 (10%), and PCB for 6 (4%). Overlapping conditions were diagnosed for some patients: FS and GBS (5%), PCB and FS (5%), BBE and GBS (4%), and PCB and BBE (1%). Patients who initially had bulbar palsy developed not only PCB but FS or BBE. The population of anti-GT1a-positive patients frequently had ophthalmoplegia, ataxia, and areflexia, whereas the subpopulation who had anti-GT1a IgG without GQ1b reactivity frequently had preceding diarrhea as well as oropharyngeal, neck, and limb weakness. Patients with anti-GT1a IgG presented a variety of clinical conditions, indicative of a continuous clinical spectrum. A major part of this clinical variation was due to the coexistence of anti-GQ1b IgG. The presence of a common autoantibody (anti-GT1a IgG) and overlapping illnesses suggests that PCB is closely related not only to GBS but to FS and BBE as well.

Adolescent↗

PubMed2004

Bickerstaff's brainstem encephalitis associated with IgM antibodies to GM1b and GalNAc-GD1a.

This is the first report of a case of Bickerstaff's brainstem encephalitis (BBE) associated with IgM antibodies to GM1b and GalNAc-GD1a. Subsequent to Campylobacter jejuni enteritis, the patient rapidly developed consciousness disturbance and hyperreflexia in addition to external ophthalmoplegia and cerebellar-like ataxia. EEG showed transient 7 Hz monorhythmic theta activities, predominantly in the front-central area. He received high doses of immunoglobulin intravenously and had completely recovered 3 months later. High anti-GM1b and anti-GalNAc-GD1a IgM antibody titers present during the acute phase decreased with his clinical improvement. An absorption study showed the anti-GM1b and anti-GalNAc-GD1a IgM antibodies to be cross-reactive. Anti-GM1b and anti-GalNAc-GD1a antibodies have been detected in some patients who developed Guillain-Barré syndrome after C. jejuni enteritis, whereas the anti-GQ1b IgG antibody is associated with BBE. Infection by C. jejuni bearing a GM1b-like or GalNAc-GD1a-like lipooligosaccharide may trigger the production of anti-GalNAc-GD1a and anti-GM1b IgM antibodies. It is not clear why our patient developed BBE rather than Guillain-Barré syndrome. These antibodies may, however, prove useful serological markers for identifying BBE patients who do not have the anti-GQ1b IgG antibody.

Ataxia↗

PubMed2004

Natural interferon alpha treatment and interferon alpha receptor 2 levels in acute hepatitis C.

Efficacy of interferon (IFN) therapy during the acute phase of hepatitis C infection is promising, although the optimal regimen has yet to be determined. It is not known whether the known prognostic factors for chronic hepatitis C (CHC) influence the effect of IFN in acute hepatitis C (AHC). Seventeen patients with AHC were analyzed for hepatic IFN alpha receptor 2 (IFNAR2) prior to IFN treatment. All patients were subsequently treated with either 168 million units (MU) or 336 MU of natural IFN alpha. Seventeen age-matched samples of CHC were provided as controls. The overall sustained response rate was 64.7% (11/17). In patients who received a total dose of 168 MU IFN, the sustained response rate was 28.6% (2/7), and in those who received 336 MU of IFN, the sustained response rate was 90.0% (9/10). The peaks of ALT and HCV-RNA quantity were not associated with the response to IFN. The hepatic IFNAR2 levels were 1.52 +/- 0.34 densitometry units and 0.92 +/- 0.16 in AHC and CHC, respectively (P = 0.042). There was no difference in hepatic IFNAR2 levels between sustained virological responders (SVR) and nonsustained virological responders (NR). The hepatic receptor levels were higher in AHC than in CHC patients. The levels of hepatic IFNAR2 did not differ in SVR and NR, indicating that high-dose natural IFN alpha treatment is effective for AHC, irrespective of the levels of hepatic IFNAR2.

Acute Disease↗