Circulating microRNAs as potential biomarkers for genetic generalized epilepsies: a three microRNA panel.

BACKGROUND AND PURPOSE: Genetic generalized epilepsies (GGEs) encompass a group of syndromes of mainly genetic causes, characterized by the involvement of both hemispheres. MicroRNAs (miRNAs) are small non-coding RNAs with a critical role in the regulation of neuronal biological processes through gene expression modulation. Dysregulated miRNA expression has been shown in epilepsy. Due to their stability in biological fluids like serum, miRNAs have assumed a prominent role in biomarker research. Our aim was to evaluate circulating levels of three miRNAs in GGE patients and assess their putative diagnostic value. METHODS: MiR-146a, miR-155 and miR-132 were quantified by real-time polymerase chain reaction in the serum of 79 GGE patients (47 women, 32 men, 35.1 ± 12.4 years) and 67 healthy individuals (41 women, 26 men, 42.4 ± 10.1 years). Relative expression values were calculated using the 2-ΔΔCt method. Receiver operating characteristic curve analysis was performed to assess diagnostic value. MiRNA expression was correlated with clinicopathological features. RESULTS: Serum levels of miR-146a and miR-155 were significantly upregulated in GGE patients relative to controls (3.13 and 6.05, respectively). Combined miR-146a, miR-155 and miR-132 serum levels performed well as a diagnostic biomarker, discriminating GGE patients from controls with an area under the curve of 0.85, 80% specificity and 73% sensitivity. CONCLUSIONS: Our results indicate that miR-146a, miR-155 and miR-132 may partake in GGE epileptogenesis. A panel of three circulating miRNAs with potential value as a GGE biomarker is reported for the first time. Novel biomarkers may help to identify new treatment targets and contribute to improved patients' quality of life through earlier diagnosis and a more precise prognosis.

Synaptic tagging and capture in the living rat.

In isolated hippocampal slices, decaying long-term potentiation can be stabilized and converted to late long-term potentiation lasting many hours, by prior or subsequent strong high-frequency tetanization of an independent input to a common population of neurons-a phenomenon known as 'synaptic tagging and capture'. Here we show that the same phenomenon occurs in the intact rat. Late long-term potentiation can be induced in CA1 during the inhibition of protein synthesis if an independent input is strongly tetanized beforehand. Conversely, declining early long-term potentiation induced by weak tetanization can be converted into lasting late long-term potentiation by subsequent strong tetanization of a separate input. These findings indicate that synaptic tagging and capture is not limited to in vitro preparations; the past and future activity of neurons has a critical role in determining the persistence of synaptic changes in the living animal, thus providing a bridge between cellular studies of protein synthesis-dependent synaptic potentiation and behavioural studies of memory persistence.

[Uveitis]. / Uveíte.

Uveitis is a general term that refers to the inflammation of uveal tract, which is an important cause of blindness in young people. It is well known that uveitis can be the initial manifestation of a systemic disease (S.D.), and may appear years before the diagnosis of the primary disease. Uveitis should be integrated in a systemic study with proper testing. Therefore, the diagnosis is a matter for the ophthalmologist and the Specialist in internal medicine. We have made a retrospective study of 71 patients with chronic uveitis or panuveitis. We found 54.9% of primary uveitis and 45.1% of S.D. associated uveitis, most of them with Behçet's disease (16/71) and Ankylosing Spondilytis (7/71). HLA typing of the patients showed a decreased frequency of HLA A1 and HLA A3 antigens and an increased frequency of the HLA B27 antigen, when compared to a Portuguese control population. We confirmed the important role of HLA B27 as an independent susceptibility factor for anterior uveitis. The lowest HLA A3 frequency was observed in the group of S.D. associated uveitis, which could suggest that this antigen may play a role as a factor of resistance to uveitis.

Anomalies of the CD8+ T cell pool in haemochromatosis: HLA-A3-linked expansions of CD8+CD28- T cells.

The present study consists of a phenotypic and functional characterization of peripheral blood T lymphocytes in a group of 21 patients with hereditary haemochromatosis (HH), an MHC class I-linked genetic disease resulting in iron overload, and a group of 30 healthy individuals, both HLA-phenotyped. The HH patients studied showed an increased percentage of CD8+ CD28- T cells with a corresponding reduction in the percentage of CD8+ CD28+ T cells in peripheral blood relative to healthy blood donors. No anomalies of CD28 expression were found in the CD4+ subset. The presence of the HLA-A3 antigen but not age accounted for these imbalances. Thus, an apparent failure of the CD8+ CD28+ T cell population 'to expand', coinciding with an 'expansion' of CD8+ CD28- T cells in peripheral blood of HLA-A3+ but not HLA-A3- HH patients was observed when compared with the respective HLA-A3-matched control group. A significantly higher percentage of HLA-DR+ but not CD45RO+ cells was also found within the peripheral CD8+ T cell subset in HH patients relative to controls. Phytohaemagglutinin (PHA) stimulation of peripheral blood mononuclear cells (PBMC) for 5 days showed: (i) that CD8+ CD28+ T cells both in controls and HH were able to expand in vitro; (ii) that CD8+ CD28- T cells decreased markedly after activation in controls but not in HH patients. Moreover, functional studies showed that CD8+ cytotoxic T lymphocytes (CTL) from HH patients exhibited a diminished cytotoxic activity (approx. two-fold) in standard 51Cr-release assays when compared with CD8+ CTL from healthy controls. The present results provide additional evidence for the existence of phenotypic and functional anomalies of the peripheral CD8+ T cell pool that may underlie the clinical heterogeneity of this iron overload disease. They are of particular relevance given the recent discovery of a novel mutated MHC class I-like gene in HH.

Importance of establishing appropriate local reference values for the screening of hemochromatosis: a study of three different control populations and 136 hemochromatosis family members. Hemochromatosis Clinical and Research Group.

Hemochromatosis is a human leukocyte antigen-linked (HLA-linked), potentially lethal disorder of iron metabolism with a high prevalence in white populations albeit an autosomal recessive mode of transmission. The diagnosis and treatment at early stages of the disease are critical to the prevention of the morbidity and mortality caused by the iron overload. After the identification of the first cases of hemochromatosis in Portugal, a screening program was started with a systematic search for the disease among family members of the patients, as well as in subjects from the normal population. In this study we analyze the results obtained with a total of 136 family members from 15 different families and 353 control subjects from three different villages, two in the north and one in the south of Portugal. We establish reference values for the biochemical tests used in the screening for iron overload and analyze the factors that affect those results. Besides sex-related differences, factors that were found to influence biochemical parameters most significantly included age and levels of daily alcohol intake. In addition, differences in iron status were identified between the populations from the regions in the north and the south of the country. We estimate, by HLA typing and family studies, a gene frequency for hemochromatosis of 0.14 that corresponds to a frequency of homozygotes and heterozygotes of 0.019 and 0.24, respectively.

Ferritin secretion by human mononuclear cells: association with HLA phenotype.

A number of different observations indicate that cells of the immune system can participate in the prevention of potential tissue toxicity from iron accumulation and that, in turn, iron and iron binding proteins have important effects on immune responses. The current studies were undertaken to examine a specific aspect of the interaction of iron with human peripheral blood mononuclear cells. A modified hemolytic plaque-forming assay was used to measure ferritin secretion in vitro by phytohemagglutinin activated or nonactivated mononuclear cells in response to stimulation by ferric citrate. Cells from 55 unrelated healthy subjects collectively representing all well-defined HLA-A, B, C, and DR antigens were studied. There were large reproducible differences in the numbers of plaques formed by different individuals, and there was a statistically significant increase in the frequency of the HLA determinant A3 among the "low" responders. Ferritin secretion measured with an antibody specific for acidic ferritin also showed a distinction between A3 and non-A3 donors. In preliminary cell mixing studies, ferritin secretion by mononuclear cells was shown to require the presence of monocytes and to be influenced by the secretion characteristics of both the monocyte and the T-cell donor. These results may provide a clue to the mechanism of development of idiopathic hemochromatosis which is an HLA-A-linked autosomal recessive disease associated with the specific HLA antigen HLA-A3.