Sibel P. Yentür

Identification of multiple genetic susceptibility loci in Takayasu arteritis

Takayasu arteritis is a rare inflammatory disease of large arteries. The etiology of Takayasu arteritis remains poorly understood, but genetic contribution to the disease pathogenesis is supported by the genetic association with HLA-B*52. We genotyped ~200,000 genetic variants in two ethnically divergent Takayasu arteritis cohorts from Turkey and North America by using a custom-designed genotyping platform (Immunochip). Additional genetic variants and the classical HLA alleles were imputed and analyzed. We identified and confirmed two independent susceptibility loci within the HLA region (r(2) < 0.2): HLA-B/MICA (rs12524487, OR = 3.29, p = 5.57 × 10(-16)) and HLA-DQB1/HLA-DRB1 (rs113452171, OR = 2.34, p = 3.74 × 10(-9); and rs189754752, OR = 2.47, p = 4.22 × 10(-9)). In addition, we identified and confirmed a genetic association between Takayasu arteritis and the FCGR2A/FCGR3A locus on chromosome 1 (rs10919543, OR = 1.81, p = 5.89 × 10(-12)). The risk allele in this locus results in increased mRNA expression of FCGR2A. We also established the genetic association between IL12B and Takayasu arteritis (rs56167332, OR = 1.54, p = 2.18 × 10(-8)).

Interleukin-6 in neuro-Behçet's disease: association with disease subsets and long-term outcome.

Increased cerebrospinal fluid (CSF) IL-6 has been reported in patients with Behçets disease (BD) and neurological involvement. To elucidate the value of IL-6 as a marker of disease activity, serum and CSF IL-6 levels of 68 BD patients with acute (26) or chronic progressive (14) parenchymal involvement (pNB), dural sinus thrombosis (10), ischemic stroke (5) or headache (13) were measured by ELISA. Samples from multiple sclerosis, subacute sclerosing panencephalitis, and noninflammatory neurological disorders were used as controls. CSF but not serum samples of neuro-BD patients with acute pNB displayed significantly increased IL-6 levels as compared to other groups. Chronic progressive pNB patients also showed increased CSF IL-6 levels, albeit less prominent. Patients with increased CSF IL-6 levels were more likely to have increased CSF cell counts and total protein levels and these three parameters were correlated with long-term (3 years) disease outcome. In four chronic progressive patients, IL-6 was elevated despite otherwise normal CSF. CSF IL-6 seems to be a marker of disease activity and long-term outcome for pNB along with CSF cell count and protein levels. CSF IL-6 could be used in chronic progressive patients who have normal CSF cell, or protein levels to detect disease activity.

Cytokines and chemokines in neuro-Behçet's disease compared to multiple sclerosis and other neurological diseases

Cytokines and chemokines in cerebrospinal fluid (CSF) can have implications on the pathogenesis of neuro-Behçets disease (NB). CSF and serum samples from 33 patients with NB, 25 with multiple sclerosis (MS), 20 patients with infectious and/or inflammatory neurological diseases (IN) and 14 with other noninflammatory neurological diseases (NIN) were investigated by ELISA. In the CSF, CXCL10 levels were significantly higher in NB and IN than NIN and MS, whereas CXCL8 was increased in NB compared to NIN. CCL2 levels in MS CSF and sera were lower, whereas CXCL8 in MS sera was higher than the other groups. IL-12 was elevated in CSF of IN compared to NB and NIN and also in the CSF of MS compared to NIN. No difference was detected for IL-10 and IL-17. These results reflect that NB has a mediator pattern in resemblance with non-specific inflammations such as neuro-infections compared to autoimmune disorders such as multiple sclerosis, suggesting that a currently unknown infection might be the trigger of a vasculitic process in the central nervous system (CNS).

Anti-αB-crystallin immunoreactivity in inflammatory nervous system diseases

AbstractαB-Crystallin, a small heat shock protein, is an immuno-dominant antigen with increased tissue expression in demyelination. To investigate the humoral response against αB-crystallin, the sera and CSF samples of patients with multiple sclerosis (MS), Guillain-Barré syndrome (GBS), neuro-Behçets disease (NBD) and other non-inflammatory neurological disease (NIND) were screened by enzyme-linked immunosorbent assay for anti-αB-crystallin IgG and IgM antibodies. Serum and CSF IgG antibody responses to αB-crystallin were significantly elevated only in NBD patients (serum IgG, NBD 1.29±0.49 vs NIND 0.95±0.39, p=0.01; CSF IgG, NBD 1.22±0.64 vs. NIND 0.81±0.35, P=0.01). Similarly, high serum IgM antibody titres were also detected in NBD (1.83±0.72 vs. 1.16±0.49, P=0.0005) and in MS (1.57±1.07, P=0.046), whereas elevated CSF IgM responses were observed to be high only in GBS (2.09±1.09 vs. 1.41±0.7, P=0.007). Humoral responses against αB-crystallin are increased in NBD and GBS, which may implicate this central nervous system antigen in the causation and pathogenesis of these inflammatory nervous system disorders.

Identification of Susceptibility Loci in IL6, RPS9/LILRB3, and an Intergenic Locus on Chromosome 21q22 in Takayasu Arteritis in a Genome-Wide Association Study

Takayasu arteritis is a rare large vessel vasculitis with incompletely understood etiology. This study was undertaken to perform the first unbiased genome‐wide association analysis of Takayasu arteritis.

Interleukin (IL)-12, IL-2, interferon-γ gene polymorphisms in subacute sclerosing panencephalitis patients

Mutated measles virus variants have been claimed as the causing agent for subacute sclerosing panencephalitis (SSPE) developing several years after the recovery from measles infection. However, immune dysfunction may be considered related to a genetic susceptibility to this rare disease. Interleukin (IL)-2 -330 (rs2069762) and +160 (rs2069763), IL-12 p40 3′ UTR (rs3213113), and interferon (IFN)-γ+874 (rs2430561) polymorphisms are screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR-sequence-specific priming (SSP) methods in 87 SSPE patients and 106 healthy controls (HCs) as candidate genes of susceptibility. The distribution of the IL12B genotypes (rs3213113) showed a trend for a significant difference (P = .053). The frequency of IL12B C allele (P = .04, OR: 1.6) and CC genotype (P = .03, OR: 3.2) were both higher in SSPE patients than in HC. The IL2 −330 genotypes revealed lower frequencies of GG genotype (P = .03, OR: 0.4) as well as G allele (P = .02, OR: 0.6) in SSPE. IL2 −330+160 TG haplotype was more frequent in patients (P = .005, OR: 1.8), whereas GG haplotype was less frequent, compared to controls (P = .02, OR: 0.6). IFNG +874 polymorphism revealed no difference. These findings implicate possible effects of genetic polymorphisms in the susceptibility to SSPE, which need to be confirmed in other populations.

Oligoclonal bands and increased cytokine levels in idiopathic intracranial hypertension.

Objectives The pathogenesis of idiopathic intracranial hypertension (IIH) is currently unknown and there are speculations about the contribution of some immunologic factors. The aim of this study is to investigate the presence of oligoclonal bands (OCBs) and cerebrospinal fluid (CSF) and/or serum cytokine levels in patients with IIH. Methods Patients fulfilling revised diagnostic criteria for IIH were included. Their demographic, clinical, ophthalmologic and laboratory features were examined. Serum and CSF samples were detected by isoelectric focusing and immunoblotting for OCBs. The samples of IIH patients and control groups were investigated by ELISA for cytokine levels. Results We detected OCBs in eight (30.77%) patients diagnosed with IIH. There were no other obvious clinical and laboratory differences of IIH profiles between the patients with and without OCBs, but frequency of vision loss was significantly higher in the group with OCBs in comparison to OCB negatives (p = 0.038). Patients with IIH had highly elevated TNF-α, IFN-γ, IL-4, IL-10, IL-12, IL-17 in their sera compared to patients with multiple sclerosis (MS) and healthy controls. Furthermore, all cytokines except TNF-α in the CSF were found significantly higher in IIH patients compared to MS controls. Conclusion The presence of OCBs and elevated cytokine levels in IIH patients may support an immunologic background in the pathophysiological pathway of this disorder.

Subacute sclerosing panencephalitis surveillance study in Istanbul

The exact incidence rate of subacute sclerosing panencephalitis (SSPE) in Turkey (and in Istanbul) is not known. We have conducted an active surveillance study to determine the epidemiological characteristics and the incidence rate of SSPE in Istanbul between the dates July 1, 2002 and July 1, 2004. We found that the incidence of SSPE in Istanbul is 2 per million. By logistic regression analysis, risk factors in SSPE development are determined as being at younger ages (OR: 1.199, 95%CI=1.047-1.372, P=0.009), living in crowded households (OR: 1.430, 95%CI=1.039-1.968, P=0.028), low education level of the mother (OR: 0.123, 95%CI=0.034-0.447, P=0.001), low household income (OR: 0.413, 95%CI=0.234-0.728, P=0.002), infants being born out of Marmara region (Istanbul is in Marmara region of Turkey) (OR: 0.358, 95%CI: 0.172-0.746, P=0.006), infants not being vaccinated against measles (OR: 0.495, 95%CI: 0.312-0.786), infants having had measles before (OR: 0.235, 95%CI: 0.135-0.411). As a result, it is found in this study that SSPE is mostly related to having measles infection, and measles vaccination is found to be highly protective against SSPE. This is the first epidemiological study in SSPE from Turkey that conveys the incidence rate in Istanbul.

Differential Cytokine Changes in Patients with Myasthenia Gravis with Antibodies against AChR and MuSK

Neuromuscular transmission failure in myasthenia gravis (MG) is most commonly elicited by autoantibodies (ab) to the acetylcholine receptor or the muscle-specific kinase, constituting AChR-MG and MuSK-MG. It is controversial whether these MG subtypes arise through different T helper (Th) 1, Th2 or Th17 polarized immune reactions and how these reactions are blunted by immunosuppression. To address these questions, plasma levels of cytokines related to various Th subtypes were determined in patients with AChR-MG, MuSK-MG and healthy controls (CON). Peripheral blood mononuclear cells (PBMC) were activated in vitro by anti-CD3, and cytokines were quantified in supernatants. In purified blood CD4+ T cells, RNA of various cytokines, Th subtype specific transcription factors and the co-stimulatory molecule, CD40L, were quantified by qRT-PCR. Plasma levels of Th1, Th2 and Th17 related cytokines were overall not significantly different between MG subtypes and CON. By contrast, in vitro stimulated PBMC from MuSK-MG but not AChR-MG patients showed significantly increased secretion of the Th1, Th17 and T follicular helper cell related cytokines, IFN-γ, IL-17A and IL-21. Stimulated expression of IL-4, IL-6, IL-10 and IL-13 was not significantly different. At the RNA level, expression of CD40L by CD4+ T cells was reduced in both AChR-MG and MuSK-MG patients while expression of Th subset related cytokines and transcription factors were normal. Immunosuppression treatment had two effects: First, it reduced levels of IL12p40 in the plasma of AChR-MG and MuSK-MG patients, leaving other cytokine levels unchanged; second, it reduced spontaneous secretion of IFN-γ and increased secretion of IL-6 and IL-10 by cultured PBMC from AChR-MG, but not MuSK-MG patients. We conclude that Th1 and Th17 immune reactions play a role in MuSK-MG. Immunosuppression attenuates the Th1 response in AChR-MG and MuSK-MG, but otherwise modulates immune responses in AChR-MG and MuSK-MG patients differentially.

Genetic heterogeneity within the HLA region in three distinct clinical subgroups of myasthenia gravis.

This study aims to investigate genetic susceptibility to early-onset and late-onset anti-acetylcholine receptor antibody positive myasthenia gravis (EOMG and LOMG) and anti-muscle specific kinase antibody positive MG (MuSK-MG) at genome-wide level in a single population. Using a custom-designed array and imputing additional variants and the classical HLA alleles in 398 patients, we detected distinct associations. In EOMG, rs113519545 in the HLA class I region (OR=5.71 [3.77-8.66], P=2.24×10(-16)), HLA-B*08:01 (OR=7.04 [3.95-12.52], P=3.34×10(-11)) and HLA-C*07:01 (OR=2.74 [1.97-3.81], P=2.07(-9)), in LOMG, rs111256513 in the HLA class II region (OR=2.22 [1.59-3.09], P=2.48×10(-6)) and in MuSK-MG, an intronic variant within HLA-DQB1 (rs68081734, OR=5.86, P=2.25×10(-14)) and HLA-DQB1*05:02 (OR=8.56, P=6.88×10(-13)) revealed the most significant associations for genome-wide significance. Differential genetic susceptibility within the HLA to EOMG, LOMG and MuSK-MG has been established in a population from Turkey.