Mitsuhiro Miyashita

Glyoxalase I Retards Renal Senescence

Although kidney functions deteriorate with age, little is known about the general morphological alterations and mechanisms of renal senescence. We hypothesized that carbonyl stress causes senescence and investigated the possible role of glyoxalase I (GLO1), which detoxifies precursors of advanced glycation end products in the aging process of the kidney. We observed amelioration of senescence in GLO1-transgenic aged rats (assessed by expression levels of senescence markers such as p53, p21(WAF1/CIP1), and p16(INK4A)) and a positive rate of senescence-associated β-galactosidase (SABG) staining, associated with reduction of renal advanced glycation end product accumulation (estimated by the amount of carboxyethyl lysine). GLO1-transgenic rats showed amelioration of interstitial thickening (observed as an age-related presentation in human renal biopsy specimens) and were protected against age-dependent decline of renal functions. We used GLO1 overexpression or knockdown in primary renal proximal tubular epithelial cells to investigate the effect of GLO1 on cellular senescence. Senescence markers were significantly up-regulated in renal proximal tubular epithelial cells at late passage and in those treated with etoposide, a chemical inducer of senescence. GLO1 cellular overexpression ameliorated and knockdown enhanced the cellular senescence phenotypes. Furthermore, we confirmed the association of decreased GLO1 enzymatic activity and age-dependent deterioration of renal function in aged humans with GLO1 mutation. These findings indicate that GLO1 ameliorates carbonyl stress to retard renal senescence.

Utility of Scalp Hair Follicles as a Novel Source of Biomarker Genes for Psychiatric Illnesses

BACKGROUND Identifying beneficial surrogate genetic markers in psychiatric disorders is crucial but challenging. METHODS Given that scalp hair follicles are easily accessible and, like the brain, are derived from the ectoderm, expressions of messenger RNA (mRNA) and microRNA in the organ were examined between schizophrenia (n for first/second = 52/42) and control subjects (n = 62/55) in two sets of cohort. Genes of significance were also analyzed using postmortem brains (n for case/control = 35/35 in Brodmann area 46, 20/20 in cornu ammonis 1) and induced pluripotent stem cells (n = 4/4) and pluripotent stem cell-derived neurospheres (n = 12/12) to see their role in the central nervous system. Expression levels of mRNA for autism (n for case/control = 18/24) were also examined using scalp hair follicles. RESULTS Among mRNA examined, FABP4 was downregulated in schizophrenia subjects by two independent sample sets. Receiver operating characteristic curve analysis determined that the sensitivity and specificity were 71.8% and 66.7%, respectively. FABP4 was expressed from the stage of neurosphere. Additionally, microarray-based microRNA analysis showed a trend of increased expression of hsa-miR-4449 (p = .0634) in hair follicles from schizophrenia. hsa-miR-4449 expression was increased in Brodmann area 46 from schizophrenia (p = .0007). Finally, we tested the expression of nine putative autism candidate genes in hair follicles and found decreased CNTNAP2 expression in the autism cohort. CONCLUSIONS Scalp hair follicles could be a beneficial genetic biomarker resource for brain diseases, and further studies of FABP4 are merited in schizophrenia pathogenesis.

Clinical Features of Schizophrenia With Enhanced Carbonyl Stress

Accumulating evidence suggests that advanced glycation end products, generated as a consequence of facilitated carbonyl stress, are implicated in the development of a variety of diseases. These diseases include neurodegenerative illnesses, such as Alzheimer disease. Pyridoxamine is one of the 3 forms of vitamin B6, and it acts by combating carbonyl stress and inhibiting the formation of AGEs. Depletion of pyridoxamine due to enhanced carbonyl stress eventually leads to a decrease in the other forms of vitamin B6, namely pyridoxal and pyridoxine. We previously reported that higher levels of plasma pentosidine, a well-known biomarker for advanced glycation end products, and decreased serum pyridoxal levels were found in a subpopulation of schizophrenic patients. However, there is as yet no clinical characterization of this subset of schizophrenia. In this study, we found that these patients shared many clinical features with treatment-resistant schizophrenia. These include a higher proportion of inpatients, low educational status, longer durations of hospitalization, and higher doses of antipsychotic medication, compared with patients without carbonyl stress. Interestingly, psychopathological symptoms showed a tendency towards negative association with serum vitamin B6 levels. Our results support the idea that treatment regimes reducing carbonyl stress, such as supplementation of pyridoxamine, could provide novel therapeutic benefits for this subgroup of patients.

High-resolution copy number variation analysis of schizophrenia in Japan

Recent schizophrenia (SCZ) studies have reported an increased burden of de novo copy number variants (CNVs) and identified specific high-risk CNVs, although with variable phenotype expressivity. However, the pathogenesis of SCZ has not been fully elucidated. Using array comparative genomic hybridization, we performed a high-resolution genome-wide CNV analysis on a mainly (92%) Japanese population (1699 SCZ cases and 824 controls) and identified 7066 rare CNVs, 70.0% of which were small (<100 kb). Clinically significant CNVs were significantly more frequent in cases than in controls (odds ratio=3.04, P=9.3 × 10−9, 9.0% of cases). We confirmed a significant association of X-chromosome aneuploidies with SCZ and identified 11 de novo CNVs (e.g., MBD5 deletion) in cases. In patients with clinically significant CNVs, 41.7% had a history of congenital/developmental phenotypes, and the rate of treatment resistance was significantly higher (odds ratio=2.79, P=0.0036). We found more severe clinical manifestations in patients with two clinically significant CNVs. Gene set analysis replicated previous findings (e.g., synapse, calcium signaling) and identified novel biological pathways including oxidative stress response, genomic integrity, kinase and small GTPase signaling. Furthermore, involvement of multiple SCZ candidate genes and biological pathways in the pathogenesis of SCZ was suggested in established SCZ-associated CNV loci. Our study shows the high genetic heterogeneity of SCZ and its clinical features and raises the possibility that genomic instability is involved in its pathogenesis, which may be related to the increased burden of de novo CNVs and variable expressivity of CNVs.

Advanced glycation end products and schizophrenia: A systematic review

Oxidative stress has become an exciting area of research on schizophrenia, which is a highly prevalent condition that affects approximately 1% of the worldwide population. Advanced glycation end products (AGEs), which are considered metabolic biomarkers of increased oxidative stress, have a pathogenic role in the development and progression of different oxidative stress-based diseases including atherosclerosis, diabetes, neurodegenerative disorders and schizophrenia. AGE formation and accumulation as well as the activation of its receptor (RAGE) can lead to signaling through several inflammatory signaling pathways and further damaging effects. This systematic review is based on a search conducted in July 2014 in which 6 studies were identified that met our criteria. In this work, we describe how recent methodological advances regarding the role of AGEs may contribute to a better understanding of the pathophysiology of schizophrenia and provide a different approach in the comprehension of the relationship between cardiovascular disease and schizophrenia. These latest findings may lead to new directions for future research on novel diagnostic and treatment strategies.

Schizophrenia: maternal inheritance and heteroplasmy of mtDNA mutations.

Role of mitochondrial pathology in schizophrenia has not been fully clarified. We searched for distinctive variants in mtDNA extracted from the gray matter of postmortem brains and from peripheral blood samples. We screened mtDNA region containing 5 genes encoding subunits of cytochrome c oxidase and ATPases. Polymorphisms not already reported in databases are recorded as unregistered rare variants. Four unregistered, non-synonymous rare variants were detected in 4 schizophrenic samples. Seven registered non-synonymous variants were not previously detected in non-psychotic Japanese samples registered in the mtSNP database. These variants may contribute to disease pathophysiology. In one family, compound mutations showed co-segregation with schizophrenia. MtDNA mutations could confer a risk for schizophrenia in the Japanese population, although further analyses are needed.

Replication of enhanced carbonyl stress in a subpopulation of schizophrenia

OXYTOCIN (OXT) SIGNALING THROUGH its receptor (OXTR) has been implicated in the pathophysiology of autism spectrum disorders (ASD). Our previous study showed a decrease in relative ratios of N-acetylaspartate to creatine (NAA/Cr) in the right medial temporal lobe (MTL) in ASD individuals. Here, we investigated the effects of OXTR on right MTL NAA/Cr in ASD individuals. This study was approved by the Ethics Committee on Genetics of the Niigata University School of Medicine. All participants and their parents provided written informed consent. DNA samples were taken from 26 ASD individuals (21 boys and five girls; mean age = 13.1 ± 3.6 years) who overlapped with those in our previous study. Detailed protocol for proton magnetic resonance spectroscopy has been previously described. We genotyped 14 single nucleotide polymorphisms (SNP) in OXTR using the TaqMan 5′-exonuclease assay. We compared mean right MTL NAA/Cr between major allele homozygotes and minor allele carriers of each SNP using ANCOVA with age and full-scale IQ as covariates. Power calculations were performed using G*Power v3.1.7 (http://www.psycho.uni-duesseldorf.de/ abteilungen/aap/gpower3). We observed nominally significant differences in mean NAA/Cr in the right MTL, including the amygdala– hippocampus region, between major allele homozygotes and minor allele carriers of two SNP: 1.14 ± 0.23 and 1.40 ± 0.21, respectively (P = 0.010) for rs9840864; and 1.18 ± 0.27 and 1.41 ± 0.18, respectively (P = 0.020) for rs11706648. Our study is in line with earlier studies reporting an association between OXTR and neuroimaging indices for the amygdala and hippocampus. There are some limitations of the present study. First, the associations between two SNP and the right MTL NAA/Cr did not survive a multiple testing correction. Sixty-two samples are needed to detect the associations with an α of 0.0036 (0.05/ 14) and a power of 0.8, under the favorable assumption that the effect size d is 1.0 and the numbers of each group are equal. Second, we used a ratio rather than absolute quantification of neurochemical metabolites. As such, we cannot determine whether NAA/Cr variation by the genetic polymorphisms was due to an alteration of NAA or Cr concentration. In conclusion, our findings obtained from an imaginggenetics approach provided preliminary evidence for the association between OXTR and neuronal function in the MTL in ASD individuals. Advances in such an approach appear to be promising for understanding ASD with diverse causes. REFERENCES

Carbonyl stress and schizophrenia

Appropriate biological treatment and psychosocial support are essential to achieve and maintain recovery for patients with schizophrenia. Despite extensive efforts to clarify the underlying disease mechanisms, the main cause and pathophysiology of schizophrenia remain unclear. This is due in large part to disease heterogeneity, which results in biochemical differences within a single disease entity. Other factors include variability across clinical symptoms and disease course, along with varied risk factors and treatment responses. Although schizophrenias positive symptoms are largely managed through treatment with atypical antipsychotics, new classes of drugs are needed to address the unmet medical need for improving cognitive dysfunction and promoting recovery of negative symptoms in these patients. Accumulation of toxic reactive dicarbonyls, such as methylglyoxal, are typical indicators of carbonyl stress, and result in the modification of proteins and the formation of advanced glycation end products, such as pentosidine. In June 2010, we reported on idiopathic carbonyl stress in a subpopulation of schizophrenia patients, leading to a failure of metabolic systems with plasma pentosidine accumulation and serum pyridoxal depletion. Our findings suggest two markers, pentosidine and pyridoxal, as beneficial for distinguishing a specific subgroup of schizophrenics. We believe that this information, derived from in vitro and in vivo studies, is beneficial in the search for personalized and hopefully more effective treatment regimens in schizophrenia. Here, we define a subtype of schizophrenia based on carbonyl stress and the potential for using carbonyl stress as a biomarker in the challenge of overcoming heterogeneity in schizophrenia treatment.

Characterization of modified proteins in plasma from a subtype of schizophrenia based on carbonyl stress: Protein carbonyl is a possible biomarker of psychiatric disorders.

Although its well known that protein carbonyl (PCO) and advanced glycation end-products (AGEs) levels are elevated in plasma from patients with renal dysfunction, we recently identified patients who had no renal dysfunction but possessed high levels of plasma pentosidine (PEN), which is an AGEs, and low vitamin B6 levels in serum. In this study, we investigated the status of carbonyl stress to characterize the subtype of schizophrenia. When plasma samples were subjected to Western blot analysis for various AGEs, clear differences were only observed with the anti-PEN antibody in the plasma from schizophrenic patients. Moreover, we determined the formation of protein carbonyl (PCO), a typical indicator of carbonyl stress, occurred prior to the accumulation of PEN in the plasma of schizophrenic patients. PCO levels in the plasma from schizophrenic patients were significantly higher than that from healthy subjects. Western blots analysis clearly showed that albumin and IgG were markedly carbonylated in the plasma of some patients. Thus, PCOs may be a novel marker of carbonyl stress-type schizophrenia in addition to albumin containing PEN structure.

Idiopathic carbonyl stress in a drug-naive case of at-risk mental state

full-scale intelligence quotient (IQ) was 124, verbal IQ was 130, and performance IQ was 112. Marked deviations were seen in some subtests of the WAIS-III, with very high performance in Vocabulary and Information, and very low performance in Letter–number sequencing and Picture completion. Magnetic resonance imaging (MRI) of the head and encephalography yielded results within normal limits. These findings suggested autistic disorder (high-functioning autism) according to DSM-IV-TR criteria. Collagens represent a large family of structurally related extracellular matrix proteins essential for development, cell attachment, platelet aggregation and tensile strength in connective tissues such as bone, skin, ligaments, tendons, and blood vessels. Cupo et al. described abnormalities in the development of the central nervous system (CNS) in EDS, including a heterotropic formation in the CNS. Although no CNS abnormality was evident on MRI in the present case, loss of elasticity and strength of collagen presumably contributed to structural failure in connective tissues of the CNS. We speculate that associations exist between connective tissue diseases and autistic disorders, and that connective tissue abnormalities may contribute to autistic symptoms.