Development of telencephalin in the human cerebrum

The TARC/sICAM5 Ratio in Patient Plasma is a Candidate Biomarker for Drug Resistant Epilepsy

Epilepsy is a common affliction that involves inflammatory processes. There are currently no definitive chemical diagnostic biomarkers in the blood, so diagnosis is based on a sometimes expensive synthesis of clinical observation, radiology, neuro-psychological testing, and interictal and ictal EEG studies. Soluble ICAM5 (sICAM5), also known as telencephalin, is an anti-inflammatory protein of strictly central nervous system tissue origin that is also found in blood. Here we have tested the hypothesis that plasma concentrations of select inflammatory cytokines, including sICAM5, might serve as biomarkers for epilepsy diagnosis. To test this hypothesis, we developed a highly sensitive and accurate electrochemiluminescent ELISA assay to measure sICAM5 levels, and measured levels of sICAM5 and 18 other inflammatory mediators in epilepsy patient plasma and controls. Patient samples were drawn from in-patients undergoing video-EEG monitoring, without regard to timing of seizures. Differences were defined by t-test, and Receiver Operating Condition (ROC) curves determined the ability of these tests to distinguish between the two populations. In epilepsy patient plasmas, we found that concentrations of anti-inflammatory sICAM5 are reduced (p = 0.002) and pro-inflammatory IL-1β, IL-2, and IL-8 are elevated. TARC (thymus and activation regulated chemokine, CCL17) concentrations trend high. In contrast, levels of BDNF and a variety of other pro-inflammatory mediators are not altered. Based on p-value and ROC analysis, we find that the ratio of TARC/sICAM5 discriminates accurately between patients and controls, with an ROC Area Under the Curve (AUC) of 1.0 (p = 0.034). In conclusion, we find that the ratio of TARC to sICAM5 accurately distinguishes between the two populations and provides a statistically and mechanistically compelling candidate blood biomarker for drug resistant epilepsy.

Structure, Expression, and Function of ICAM-5

Cell adhesion is of utmost importance in normal development and cellular functions. ICAM-5 (intercellular adhesion molecule-5, telencephalin, TLN) is a member of the ICAM family of adhesion proteins. As a novel cell adhesion molecule, ICAM-5 shares many structural similarities with the other members of IgSF, especially the ICAM subgroup; however, ICAM-5 has several unique properties compared to the other ICAMs. With its nine extracellular Ig domains, ICAM-5 is the largest member of ICAM subgroup identified so far. Therefore, it is much more complex than the other ICAMs. The expression of ICAM-5 is confined to the telencephalic neurons of the central nervous system whereas all the other ICAM members are expressed mostly by cells in the immune and blood systems. The developmental appearance of ICAM-5 parallels the time of dendritic elongation and branching, and synapse formation in the telencephalon. As a somatodendrite-specific adhesion molecule, ICAM-5 not only participates in immune-nervous system interactions, it could also participate in neuronal activity, Dendrites' targeting signals, and cognition. It would not be surprising if future investigations reveal more binding partners and other related functions of ICAM-5.

Appearance of LFA-1 in the initial stage of synaptogenesis of developing hippocampal neurons

In the present study, we found that leucocyte function-associated antigen-1 (LFA-1), and integrin (heterodimer complex of CD11a and CD18), which are abundant in immunological synapse, were expressed in developing hippocampal neurons. The expression of LFA-1 in hippocampal neurons was in the period of synaptogenesis, and synaptogenesis was inhibited by the blocking antibodies of anti-CD11a or anti-CD18 in vitro. Since it is known that LFA-1 has an important role in the immunological response, especially in immunological synapse, LFA-1 is considered to have an important role in neuronal synapse and is highly involved in synaptogenesis in the early developmental stage in vitro. In vivo, we also confirmed that CD18 was expressed in hippocampus in the early developmental stage. Telencephalin, which is a candidate for postsynaptic elements to contact LFA-1, was precisely opposed to CD18-positive structures in presynaptic elements, and telencephalin was considered to be involved in synaptogenesis. The present study showed that 17beta-estradiol of steroid hormones, which are well known to have various effects on hippocampal neurons, has a significant influence on the presynaptic expression of CD18 in synaptogenesis and inhibited synaptogenesis in the early developmental stage in vitro. These results suggest that LFA-1 plays some mechanisms in synaptic contacts and synaptogenesis of hippocampal neurons.

Dendritic overgrowth and alterations in laminar phenotypes of neocortical neurons in the newborn with semilobar holoprosencephaly

We analyzed neuronal phenotypes and dendritic growth in the newborn with semilobar holoprosencephaly and 18p deletion. We found that the holoprosencephalic neocortex retained its basic six-layered lamination but displayed a number of intralaminar and modular architectonic alterations and contained a mixture of normal and aberrant neuronal phenotypes. The most conspicious finding was the presence of the pronounced increase in soma size and total basal dendritic length of holoprosencephalic layer III pyramidal neurons in comparison to age-matched control brains. The dramatic (5-fold) dendritic overgrowth observed in associative cortico-cortical pyramidal neurons is probably related to the pronounced diminution of the cortical afferent input.

Cell adhesion molecules, leukocyte trafficking, and strategies to reduce leukocyte infiltration

Leukocyte-endothelial cell interactions are mediated by various cell adhesion molecules. These interactions are important for leukocyte extravasation and trafficking in all domestic animal species. An initial slowing of leukocytes on the vascular endothelium is mediated by selectins. This event is followed by (1) activation of beta2 integrins after leukocyte exposure to cytokines and pro-inflammatory mediators, (2) adherence of leukocyte beta2 integrins to vascular endothelial ligands (eg, intercellular adhesion molecule-1 [ICAM-1]), (3) extravasation of leukocytes into tissues through tight junctions of endothelial cells mediated by platelet and endothelial cell adhesion molecule-1 (PECAM-1), and (4) perivascular migration through the extracellular matrix via beta1 integrins. Inhibiting excessive leukocyte egress and subsequent free radical-mediated damage caused by leukocyte components may attenuate or eliminate tissue damage. Several methods have been used to modify leukocyte infiltration in various animal models. These methods include nonspecific inhibition of pro-inflammatory mediators and adhesion molecules by nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids, inhibition of cytokines and cytokine receptors, and inhibition of specific types of cell adhesion molecules, with inhibitors such as peptides and antibodies to beta2 integrins, and inhibitors of selectins, ICAMs, and vascular cell adhesion molecule-1 (VCAM-1). By understanding the cellular and molecular events in leukocyte-endothelial cell interactions, therapeutic strategies are being developed in several animal models and diseases in domestic animal species. Such therapies may have clinical benefit in the future to overcome tissue damage induced by excessive leukocyte infiltration.

A new algorithm for analysis of oligonucleotide arrays: application to expression profiling in mouse brain regions

Oligonucleotide arrays are a powerful technology for measuring the expression of thousands of genes simultaneously. Improvements in the sensitivity and precision of the measurements, which often pose a challenge to users, would assist the practical application of the technology. Here, we describe a new analysis algorithm for assessing changes in gene expression using oligonucleotide arrays. Changes in expression are detected in terms of the statistical significance (S-score) of change, which combines signals detected by multiple probe pairs according to an error model characteristic of oligonucleotide arrays. We show that the S-score is sensitive and reliable, enabling us to obtain more consistent results than with existing methods. Cluster analysis of S-score data of four brain regions exhibits patterns that are more distinctive because of improved data quality. In our case study of two mouse brain regions, over 200 genes were identified to have detectable changes between the ventral tegmental area and the prefrontal cortex. The genes with the most distinctive changes are found to be related to myelin or neurofilament synthesis, calcium signaling, and transcription factors. Many of these findings are in agreement with previous studies, using other techniques, such as in situ hybridization. Overall, our findings suggest that this new algorithm may have broad applicability for improving the analysis of oligonucleotide array data.