Effect of modulating glutamate signaling on myelinating oligodendrocytes and their development-A study in the zebrafish model.

Myelination is crucial for the development and maintenance of axonal integrity, especially fast axonal action potential conduction. There is increasing evidence that glutamate signaling and release through neuronal activity modulates the myelination process. In this study, we examine the effect of manipulating glutamate signaling on myelination of oligodendrocyte (OL) lineage cells and their development in zebrafish (zf). We use the "intensity-based glutamate-sensing fluorescent reporter" (iGluSnFR) in the zf model (both sexes) to address the hypothesis that glutamate is implicated in regulation of myelinating OLs. Our results show that glial iGluSnFR expression significantly reduces OL lineage cell number and the expression of myelin markers in larvae (zfl) and adult brains. The specific glutamate receptor agonist, L-AP4, rescues this iGluSnFR effect by significantly increasing the expression of the myelin-related genes, plp1b and mbpa, and enhances myelination in L-AP4-injected zfl compared to controls. Furthermore, we demonstrate that degrading glutamate using Glutamat-Pyruvate Transaminase (GPT) or the blockade of glutamate reuptake by L-trans-pyrrolidine-2,4-dicarboxylate (PDC) significantly decreases myelin-related genes and drastically declines myelination in brain ventricle-injected zfl. Moreover, we found that myelin-specific ClaudinK (CldnK) and 36K protein expression is significantly decreased in iGluSnFR-expressing zfl and adult brains compared to controls. Taken together, this study confirms that glutamate signaling is directly required for the preservation of myelinating OLs and for the myelination process itself. These findings further suggest that glutamate signaling may provide novel targets to therapeutically boost remyelination in several demyelinating diseases of the CNS.

No association of PTPN22 R620W gene polymorphism with rheumatic heart disease and systemic lupus erythematosus.

Rheumatic heart disease (RHD) or acute rheumatic fever (ARF) develops as a consequence of an exaggerated immune response to Group A beta haemolytic streptococci causing pharyngitis. The molecular mimicry appears between human cardiac myosin and M protein of group A streptococcal membranes. The polymorphism of the protein tyrosine phosphatase nonreceptor 22 (PTPN22) gene, which encodes an important negative regulator of T cell activation, has been reported to be associated with susceptibility to several autoimmune diseases such as SLE and RA. The objective of this study was to investigate whether PTPN22 R620W polymorphism confers susceptibility to RHD in Turkish population. PTPN 22 R620W (rs2476601, A/G) polymorphism was genotyped by PCR-RFLP in 121 patients with RHD who fulfilling the revised classification criteria of Jones, and 160 healthy control (HC), and also 137 SLE as a diseased-control. The frequency of GG and AG genotypes were found to be 94% (114), 6% (7) in RHD, respectively and 96% (153) and 4% (7) in HC, respectively. The homozygous AA genotype was not present in RHD and HC. There was no statistically significant difference between RHD and HC according to the frequency of AG heterozygote genotype (P = 0.831; OR = 1.13; 95% CI 0.37-3.46). The frequency of the rare allele A was also very similar in RHD patients and HC (3, 2% respectively). A similar result was also found between SLE and HC. Our results demonstrated that the PTPN22 R620W polymorphism is not associated with RHD nor with SLE in Turkish population.

Serum interleukin-37 level and interleukin-37 gene polymorphism in patients with Behçet disease.

Behçet's disease (BD) is a chronic inflammatory disease. The etiopathogenesis of BD is not well understood and several cytokines and genetic factors have been investigated. Interleukin (IL)-37, which a member of IL-1 family is an anti-inflammatory cytokine. The aim of the study was to analyze serum IL-37 level and IL-37 gene polymorphisms to assess its possible role in BD. Two hundred twenty-three patients with BD and 80 healthy controls (HC) were enrolled. Serum IL-37 level was measured using an enzyme-linked immunosorbent assay (ELISA). Deoksiribo Nucleic acids (DNA) were extracted using a genomic DNA isolation kit. Single nucleotide polymorphism (SNP) of IL-37 gene (rs3811047) was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) methods. Serum IL-37 level was not significantly different in BD and HC (p > 0.05). Serum IL-37 level was not associated with the disease activity (p > 0.05). However, its level was higher in mucocutaneous involvement compared with systemic involvement (p = 0.002) and HC (p = 0.005). IL-37 gene polymorphisms were similar in BD and HC (p > 0.05). IL-37 may play a role in the etiopathogenesis of BD by contributing to manifestation with more moderate clinical symptoms.

The lack of genetic association of the Toll-like receptor 2 (TLR2) Arg753Gln and Arg677Trp polymorphisms with rheumatic heart disease.

UNLABELLED: Acute rheumatic fever (ARF) is a non-suppurative inflammatory disease after group A, beta haemolytic streptococcal pharyngitis. Certain individuals can develop ARF. This finding implies variability in host predisposition to ARF. A variety of studies have linked specific genetic markers with ARF or rheumatic heart disease (RHD) as a sequelae of ARF. For this purpose, we aimed to search the role of polymorphisms in Toll-like receptor-2 and -4 (TLR2 and TLR4) gene in Turkish patients with RHD. This study included a total 84 patients with RHD, ages ranging between 18 and 65, 25 male and 59 female, fulfilling the revised classification criteria of Jones. One hundred forty healthy unrelated persons were selected as a control group. Genotype analysis: DNA was extracted from whole blood. TLR4 gene (Asp 299Gly and Thr399Ile) and TLR2 gene (Arg753Gln and Arg677Trp) polymorphisms were genotyped by the previously reported method. STATISTICAL ANALYSIS: binary logistic regression models were used. Results were expressed as odds ratios (OR) with corresponding 95% confidence intervals (95% CI). Significant level was predefined at 0.05. There was a significant difference for carrying Ile allele in the 399 position in the patients compared to healthy controls (OR = 5.26, 95% CI, 1.40-19.73, p = 0.014). In the TLR4 gene, Asp 299Gly polymorphism did not reach to a statistically significant value (OR = 3.02). We found no Arg753Gln polymorphism of the TLR2 gene in the patient group. There were three heterozygote samples in the healthy group. We did not detect Arg677Trp polymorphism of the TLR2 gene in both patient and control groups.

5 alpha steroid reductase deficiency in Turkey.

5 alpha steroid reductase 2 (5 alpha SR2) deficiency is an autosomal recessive enzyme defect causing male pseudohermaphroditism (MPH) because of an abnormally low peripheral conversion of testosterone to dihydrotestosterone (DHT), which is required for the normal differentiation of external male genitalia. The present report describes the distribution of 5 alpha steroid reductase gene mutations in the Turkish population in the light of published reports from different centers. Eight Turkish patients from unrelated Turkish families and a large pedigree of one of these patients are also discussed. These patients were followed up at Ankara University Department of Pediatric Endocrinology. The presence of Leu 55 Gln mutation in six patients out of 8 indicates the increased prevalence of this mutation in the Turkish population with different presentations. One patient out of six (patient FG) had a large pedigree of Leu 55 Gln mutation in exon 1. The pedigree of this family with marital consanguinity was very remarkable and extraordinary. A further 85 members of this family were analyzed for exon 1 Leu 55 Gln 5 alpha SR2 gene mutations. Forty two out of the 85 subjects (49.41% ) had this alteration in gene mutation. Thirty-one of them were heterozygous (18 genetic male, 13 genetic female) and 11 of them were homozygous (8 genetic male, 3 asymptomatic female carriers) for this mutation. A trinucleotid deletion at straddling codons 156 and 157 is responsible for a methionize residue at position 157 (delta Met 157) of 5 alpha SR type 2 gene which was first described in our patient NA. Two additional Turkish patients were reported by different investigators with this rare mutation and this also suggests an increased prevalence of this mutation in the Turkish population. In conclusion Leu 55 Gln mutation in exon 1 seems to be a hot spot in Turkish patients. Hence 5 alpha SR2 gene mutation analysis especially Leu 55 Gln mutation in exon 1 and delta Met 157 in exon 3, must be evaluated in Turkish patients with male pseudohermaphroditism according to our results and other Turkish patients reported by different investigators. It is important that homozygous asymptomatic female carriers be taken into consideration in this clinical entity especially in closed populations because of the risk of carrying the disease to their offspring.

Association between single nucleotide polymorphisms in prospective genes and susceptibility to ankylosing spondylitis and inflammatory bowel disease in a single centre in Turkey.

BACKGROUND/AIMS: To establish the prevalence of the single nucleotide polymorphisms (SNPs) of endoplasmic reticulum aminopeptidase 1 (ERAP1), IL-23 receptor (IL-23R), signal transducer and activator of transcription 3 (STAT-3) and Janus kinase 2 (JAK-2) in ankylosing spondylitis (AS) and inflammatory bowel disease (IBD) in a Turkish population. MATERIALS AND METHODS: A total of 562 subjects who presented at the Ankara University internal medicine departments of rheumatology and gastroenterology outpatient clinics were recruited in this study, including 365 patients with AS, 197 patients with IBD and 230 healthy controls. ERAP1, IL-23R, STAT-3 and JAK-2) were genotyped in competitive allele-specific polymerase chain reactions. RESULTS: The ERAP1 (rs26653) polymorphism was found to increase the disease risk in patients with AS and IBD compared with the control group (p=0.02 and p=0.01, respectively). In addition, this polymorphism revealed a significant relationship with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath AS Functional Index (BASFI) in patients with AS (r=0.829, p < 0.001 and r=0.731, p < 0.001, respectively). CONCLUSION: The ERAP1 gene polymorphism might be a risk factor in the pathogenesis of AS and IBD. In contrast, IL-23R gene polymorphisms may serve a protective role in AS and IBD.

Spectrum of GJB2 mutations in Turkey comprises both Caucasian and Oriental variants: roles of parental consanguinity and assortative mating.

Considerable differences exist for the spectrum of GJB2 mutations in different populations. Screening for the c.35delG mutation in 256 independent probands, 154 multiplex (familial) and 102 simplex (sporadic), coming from different regions of Turkey revealed 37 (14.5%) homozygotes. The allele frequency of c.35delG ranged from 5% to 53% in different cities. Parental consanguinity was noted in 34% of c.35delG homozygotes, yet it was 55% in c.35delG negatives (p=0.034). Further screening for GJB2 mutations in multiplex families demonstrated the presence of c.167delT and L90P mutations as well as a novel complex mutation, c.236_239delTGCAinsAGATCCG, in single alleles, leading to compound heterozygosity with c.35delG. The homozygous E120del mutation was found in another case. The V27I polymorphism was detected in five alleles, one of which was associated with the E114G change. Assortative mating was a significant factor predicting to detect biallelic mutations in the GJB2 gene. These results confirm the overwhelming majority of c.35delG in the Turkish deaf individuals as well as the presence of other changes detected in Caucasian and Asian populations.