A personal COVID-19 dendritic cell vaccine made at point-of-care: Feasibility, safety, and antigen-specific cellular immune responses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a world-wide pandemic. Internationally, because of availability, accessibility, and distribution issues, there is a need for additional vaccines. This study aimed to: establish the feasibility of personal dendritic cell vaccines to the SARS-CoV-2 spike protein, establish the safety of a single subcutaneous vaccine injection, and determine the antigen-specific immune response following vaccination. In Phase 1, 31 subjects were assigned to one of nine formulations of autologous dendritic cells and lymphocytes (DCL) incubated with 0.10, 0.33, or 1.0 µg of recombinant SARS-CoV-2 spike protein, and admixed with saline or 250 or 500 µg of granulocyte-macrophage colony-stimulating factor (GM-CSF) prior to injection, then assessed for safety and humoral response. In Phase 2, 145 subjects were randomized to one of three formulations defined by incubation with the same three quantities of spike protein without GM-CSF, then assessed for safety and cellular response. Vaccines were successfully manufactured for every subject at point-of-care. Approximately 46.4% of subjects had a grade 1 adverse event (AE); 6.5% had a grade 2 AE. Among 169 evaluable subjects, there were no acute allergic, grade 3 or 4, or serious AE. In Phase 1, anti-receptor binding domain antibodies were increased in 70% of subjects on day-28. In Phase 2, in the 127 subjects who did not have high levels of gamma interferon-producing cells at baseline, 94.4% had increased by day 14 and 96.8% by day 28. Point-of-care personal vaccine manufacturing was feasible. Further development of such subject-specific vaccines is warranted.

Layer 4 Gates Plasticity in Visual Cortex Independent of a Canonical Microcircuit

Disrupting binocular vision during a developmental critical period can yield enduring changes to ocular dominance (OD) in primary visual cortex (V1). Here we investigated how this experience-dependent plasticity is coordinated within the laminar circuitry of V1 by deleting separately in each cortical layer (L) a gene required to close the critical period, nogo-66 receptor (ngr1). Deleting ngr1 in excitatory neurons in L4, but not in L2/3, L5, or L6, prevented closure of the critical period, and adult mice remained sensitive to brief monocular deprivation. Intracortical disinhibition, but not thalamocortical disinhibition, accompanied this OD plasticity. Both juvenile wild-type mice and adult mice lacking ngr1 in L4 displayed OD plasticity that advanced more rapidly L4 than L2/3 or L5. Interestingly, blocking OD plasticity in L2/3 with the drug AM-251 did not impair OD plasticity in L5. We propose that L4 restricts disinhibition and gates OD plasticity independent of a canonical cortical microcircuit.

Reduced Prefrontal Synaptic Connectivity and Disturbed Oscillatory Population Dynamics in the CNTNAP2 Model of Autism

Loss-of-function mutations in CNTNAP2 cause a syndromic form of autism spectrum disorder in humans and produce social deficits, repetitive behaviors, and seizures in mice. However, the functional effects of these mutations at cellular and circuit levels remain elusive. Using laser-scanning photostimulation, whole-cell recordings, and electron microscopy, we found a dramatic decrease in excitatory and inhibitory synaptic inputs onto L2/3 pyramidal neurons of the medial prefrontal cortex (mPFC) of Cntnap2 knockout (KO) mice, concurrent with reduced spines and synapses, despite normal dendritic complexity and intrinsic excitability. Moreover, recording of mPFC local field potentials (LFPs) and unit spiking in vivo revealed increased activity in inhibitory neurons, reduced phase-locking to delta and theta oscillations, and delayed phase preference during locomotion. Excitatory neurons showed similar phase modulation changes at delta frequencies. Finally, pairwise correlations increased during immobility in KO mice. Thus, reduced synaptic inputs can yield perturbed temporal coordination of neuronal firing in cortical ensembles.

An inhibitory pull-push circuit in frontal cortex

Push-pull is a canonical computation of excitatory cortical circuits. Here we identify a pull-push inhibitory circuit in frontal cortex that originates in vasoactive intestinal polypeptide (VIP) expressing interneurons. During arousal, VIP cells rapidly and directly inhibit pyramidal neurons; VIP cells also indirectly excite these pyramidal neurons via parallel disinhibition. Thus, arousal exerts a feed-back pull-push influence on excitatory neurons – an inversion of the canonical push-pull of feed-forward input.

Neuregulin-1/ErbB4 Signaling Regulates Visual Cortical Plasticity

Experience alters cortical networks through neural plasticity mechanisms. During a developmental critical period, the most dramatic consequence of occluding vision through one eye (monocular deprivation) is a rapid loss of excitatory synaptic inputs to parvalbumin-expressing (PV) inhibitory neurons in visual cortex. Subsequent cortical disinhibition by reduced PV cell activity allows for excitatory ocular dominance plasticity. However, the molecular mechanisms underlying critical period synaptic plasticity are unclear. Here we show that brief monocular deprivation during the critical period downregulates neuregulin-1(NRG1)/ErbB4 signaling in PV neurons, causing retraction of excitatory inputs to PV neurons. Exogenous NRG1 rapidly restores excitatory inputs onto deprived PV cells through downstream PKC-dependent activation and AMPA receptor exocytosis, thus enhancing PV neuronal inhibition to excitatory neurons. NRG1 treatment prevents the loss of deprived eye visual cortical responsiveness in vivo. Our findings reveal molecular, cellular, and circuit mechanisms of NRG1/ErbB4 in regulating the initiation of critical period visual cortical plasticity.

High-resolution and cell-type-specific photostimulation mapping shows weak excitatory vs. strong inhibitory inputs in the bed nucleus of the stria terminalis

The bed nucleus of the stria terminalis (BNST) is a key component of the extended amygdala and has been implicated in anxiety and addiction. As individual neurons function within neural circuits, it is important to understand local microcircuits and larger network connections of identified neuronal types and understand how maladaptive changes in the BNST neural networks are induced by stress and drug abuse. However, due to limitations of classic anatomical and physiological methods, the local circuit organization of synaptic inputs to specific BNST neuron types is not well understood. In this study, we report on the application of high-resolution and cell-type-specific photostimulation methodology developed in our laboratory to local circuit mapping in the BNST. Under calibrated experimental conditions, laser photostimulation via glutamate uncaging or channelrhodopsin-2 photoactivation evokes spiking of BNST neurons perisomatically, without activating spikes from axons of passage or distal dendrites. Whole cell recordings, combined with spatially restricted photostimulation of presynaptic neurons at many different locations over a large region, allow high-resolution mapping of presynaptic input sources to single recorded neurons in the BNST. We constructed maps of synaptic inputs impinging onto corticotrophin-releasing hormone-expressing (CRH+) BNST neurons in the dorsolateral BNST and found that the CRH+ neurons receive predominant local inhibitory synaptic connections with very weak excitatory connections. Through cell-type-specific optogenetic stimulation mapping, we generated maps of somatostatin-expressing neuron-specific inhibitory inputs to BNST neurons. Taken together, the photostimulation-based techniques offer us powerful tools for determining the functional organization of local circuits of specific BNST neuron types.

Primary visual cortex shows laminar-specific and balanced circuit organization of excitatory and inhibitory synaptic connectivity

KEY POINTS

Using functional mapping assays, we conducted a quantitative assessment of both excitatory and inhibitory synaptic laminar connections to excitatory neurons in layers 2/3-6 of the mouse visual cortex (V1). Laminar-specific synaptic wiring diagrams of excitatory neurons were constructed on the basis of circuit mapping. The present study reveals that that excitatory and inhibitory synaptic connectivity is spatially balanced across excitatory neuronal networks in V1.

ABSTRACT

In the mammalian neocortex, excitatory neurons provide excitation in both columnar and laminar dimensions, which is modulated further by inhibitory neurons. However, our understanding of intracortical excitatory and inhibitory synaptic inputs in relation to principal excitatory neurons remains incomplete, and it is unclear how local excitatory and inhibitory synaptic connections to excitatory neurons are spatially organized on a layer-by-layer basis. In the present study, we combined whole cell recordings with laser scanning photostimulation via glutamate uncaging to map excitatory and inhibitory synaptic inputs to single excitatory neurons throughout cortical layers 2/3-6 in the mouse primary visual cortex (V1). We find that synaptic input sources of excitatory neurons span the radial columns of laminar microcircuits, and excitatory neurons in different V1 laminae exhibit distinct patterns of layer-specific organization of excitatory inputs. Remarkably, the spatial extent of inhibitory inputs of excitatory neurons for a given layer closely mirrors that of their excitatory input sources, indicating that excitatory and inhibitory synaptic connectivity is spatially balanced across excitatory neuronal networks. Strong interlaminar inhibitory inputs are found, particularly for excitatory neurons in layers 2/3 and 5. This differs from earlier studies reporting that inhibitory cortical connections to excitatory neurons are generally localized within the same cortical layer. On the basis of the functional mapping assays, we conducted a quantitative assessment of both excitatory and inhibitory synaptic laminar connections to excitatory cells at single cell resolution, establishing precise layer-by-layer synaptic wiring diagrams of excitatory neurons in the visual cortex.

Bidirectional global spontaneous network activity precedes the canonical unidirectional circuit organization in the developing hippocampus

Spontaneous network activity is believed to sculpt developing neural circuits. Spontaneous giant depolarizing potentials (GDPs) were first identified with single-cell recordings from rat CA3 pyramidal neurons, but here we identify and characterize a large-scale spontaneous network activity we term global network activation (GNA) in the developing mouse hippocampal slices, which is measured macroscopically by fast voltage-sensitive dye imaging. The initiation and propagation of GNA in the mouse is largely GABA-independent and dominated by glutamatergic transmission via AMPA receptors. Despite the fact that signal propagation in the adult hippocampus is strongly unidirectional through the canonical trisynaptic circuit (dentate gyrus [DG] to CA3 to CA1), spontaneous GNA in the developing hippocampus originates in distal CA3 and propagates both forward to CA1 and backward to DG. Photostimulation-evoked GNA also shows prominent backward propagation in the developing hippocampus from CA3 to DG. Mouse GNA is strongly correlated to electrophysiological recordings of highly localized single-cell and local field potential events. Photostimulation mapping of neural circuitry demonstrates that the enhancement of local circuit connections to excitatory pyramidal neurons occurs over the same time course as GNA and reveals the underlying pathways accounting for GNA backward propagation from CA3 to DG. The disappearance of GNA coincides with a transition to the adult-like unidirectional circuit organization at about 2 weeks of age. Taken together, our findings strongly suggest a critical link between GNA activity and maturation of functional circuit connections in the developing hippocampus.

Distinct physiological and developmental properties of hippocampal CA2 subfield revealed by using anti-Purkinje cell protein 4 (PCP4) immunostaining

The hippocampal CA2 subfield was initially identified by Lorente de Nó as an anatomically distinct region based on its cytoarchitectural features. Although there is an enormous body of literature on other hippocampal subfields (CA1 and CA3), relatively little is known about the physiological and developmental properties of CA2. Here we report identification of the CA2 region in the mouse by immunostaining with a Purkinje cell protein 4 (PCP4) antibody, which effectively delineates CA3/CA2 and CA2/CA1 borders and agrees well with previous cytoarchitectural definitions of CA2. The PCP4 immunostaining–delineated CA2 neurons have distinguishable differences in cell morphology, physiology, and synaptic circuit connections compared with distal CA3 and proximal CA1 regions. The average somatic sizes of excitatory cells differ across CA1–3, with the smallest to largest somatic size being CA1<CA2<CA3. CA2 excitatory cells have dense dendritic spines, but do not have thorny excrescences associated with bordering CA3 neurons. Photostimulation functional circuit mapping shows that CA2 excitatory neurons receives extensive synaptic input from CA3, but no detectable input from the dentate gyrus. CA2 excitatory cells also differ significantly from CA3 cells in intrinsic electrophysiological parameters, such as membrane capacitance and spiking rates. Although CA2 neurons differ from CA1 neurons for PCP4 and other marker expressions, these neurons have less distinct neurophysiological and morphological properties. Developmental examination revealed that PCP4 immunostaining first appears at postnatal day 4–5 and becomes successively more refined around CA2 until reaching adult form by postnatal day 21. J. Comp. Neurol. J. Comp. Neurol. 522:1333–1354, 2014. © 2013 Wiley Periodicals, Inc.

Histamine inhibits the melanin-concentrating hormone system: implications for sleep and arousal

Melanin-concentrating hormone (MCH)-producing neurons are known to regulate a wide variety of physiological functions such as feeding, metabolism, anxiety and depression, and reward. Recent studies have revealed that MCH neurons receive projections from several wake-promoting brain regions and are integral to the regulation of rapid eye movement (REM) sleep. Here, we provide evidence in both rats and mice that MCH neurons express histamine-3 receptors (H3R), but not histamine-1 (H1R) or histamine-2 (H2R) receptors. Electrophysiological recordings in brain slices from a novel line of transgenic mice that specifically express the reporter ZsGreen in MCH neurons show that histamine strongly inhibits MCH neurons, an effect which is TTX insensitive, and blocked by the intracellular presence of GDP-β-S. A specific H3R agonist, α-methylhistamine, mimicks the inhibitory effects of histamine, and a specific neutral H3R antagonist, VUF 5681, blocks this effect. Tertiapin Q (TPQ), a G protein-dependent inwardly rectifying potassium (GIRK) channel inhibitor, abolishes histaminergic inhibition of MCH neurons. These results indicate that histamine directly inhibits MCH neurons through H3R by activating GIRK channels and suggest that that inhibition of the MCH system by wake-active histaminergic neurons may be responsible for silencing MCH neurons during wakefulness and thus may be directly involved in the regulation of sleep and arousal.

Adult neurogenesis modifies excitability of the dentate gyrus

Adult-born dentate granule neurons contribute to memory encoding functions of the dentate gyrus (DG) such as pattern separation. However, local circuit-mechanisms by which adult-born neurons partake in this process are poorly understood. Computational, neuroanatomical and electrophysiological studies suggest that sparseness of activation in the granule cell layer (GCL) is conducive for pattern separation. A sparse coding scheme is thought to facilitate the distribution of similar entorhinal inputs across the GCL to decorrelate overlapping representations and minimize interference. Here we used fast voltage-sensitive dye (VSD) imaging combined with laser photostimulation and electrical stimulation to examine how selectively increasing adult DG neurogenesis influences local circuit activity and excitability. We show that DG of mice with more adult-born neurons exhibits decreased strength of neuronal activation and more restricted excitation spread in GCL while maintaining effective output to CA3c. Conversely, blockade of adult hippocampal neurogenesis changed excitability of the DG in the opposite direction. Analysis of GABAergic inhibition onto mature dentate granule neurons in the DG of mice with more adult-born neurons shows a modest readjustment of perisomatic inhibitory synaptic gain without changes in overall inhibitory tone, presynaptic properties or GABAergic innervation pattern. Retroviral labeling of connectivity in mice with more adult-born neurons showed increased number of excitatory synaptic contacts of adult-born neurons onto hilar interneurons. Together, these studies demonstrate that adult hippocampal neurogenesis modifies excitability of mature dentate granule neurons and that this non-cell autonomous effect may be mediated by local circuit mechanisms such as excitatory drive onto hilar interneurons. Modulation of DG excitability by adult-born dentate granule neurons may enhance sparse coding in the GCL to influence pattern separation.

A disinhibitory microcircuit initiates critical-period plasticity in the visual cortex

Early sensory experience instructs the maturation of neural circuitry in cortex ^1,2. This has been extensively studied in the primary visual cortex where loss of vision to one eye permanently degrades cortical responsiveness to that eye ^3,4, a phenomenon known as ocular dominance plasticity (ODP). Cortical inhibition mediates this process ^4-6, but the precise role of specific classes of inhibitory neurons in ODP is controversial. Here we report that evoked firing rates of binocular excitatory neurons in primary visual cortex immediately drop by half when vision is restricted to one eye, but gradually return to normal over the following 24 hours, despite the fact that vision remains restricted to one eye. This restoration of binocular-like excitatory firing rates following monocular deprivation results from a rapid, though transient reduction in the firing rates of fast-spiking, parvalbumin-positive (PV) interneurons, which in turn can be attributed to a decrease in local excitatory circuit input onto PV interneurons. This reduction in PV cell evoked responses following monocular lid suture is restricted to the critical period for ODP and appears to be necessary for subsequent shifts in excitatory ODP. Pharmacologically enhancing inhibition at the time of sight deprivation blocks ODP and, conversely, pharmaco-genetic reduction of PV cell firing rates can extend the critical period for ODP. These findings define the microcircuit changes initiating competitive plasticity during critical periods of cortical development. Moreover, they show that the restoration of evoked firing rates of L2/3 pyramidal neurons by PV-specific disinhibition is a key step in the progression of ocular dominance plasticity.

Optical stimulation and imaging of functional brain circuitry in a segmented laminar flow chamber

Microfluidic technology is emerging as a useful tool for the study of brain slices, offering precise delivery of chemical factors along with robust oxygen and nutrient transport. However, continued reliance upon electrode-based physiological recording poses inherent limitations in terms of physical access, as well as the number of sites that can be sampled simultaneously. In the present study, we combine a microfluidic laminar flow chamber with fast voltage-sensitive dye imaging and laser photostimulation via caged glutamate to map neural network activity across large cortical regions in living brain slices. We find that the closed microfluidic chamber results in greatly improved signal-to-noise performance for optical measurements of neural signaling. These optical tools are also leveraged to characterize laminar flow interfaces within the device, demonstrating a functional boundary width of less than 100 μm. Finally, we utilize this integrated platform to investigate the mechanism of signal propagation for spontaneous neural activity in the developing mouse hippocampus. Through the use of localized Ca(2+) depletion, we provide evidence for Ca(2+)-dependent synaptic transmission.

Cell-type specific regulation of cortical excitability through the allatostatin receptor system

Recent technical advances enable the regulation of neuronal circuit activity with high spatial and temporal resolution through genetic delivery of molecular activation or inactivation systems.Among them, the allatostatin receptor (AlstR)/ligand system has been developed for selective and quickly reversible silencing of mammalian neurons. However, targeted AlstR-mediated inactivation of specific neuronal types, particularly diverse types of inhibitory interneurons, remains to be established. In the present study, we achieved Cre-directed expression of AlstRs to excitatory and inhibitory cell-types in the cortex, and found that the AlstR-mediated inactivation was specific and robust at single-cell and neuronal population levels. Bath application of the allatostatin peptide markedly reduced spiking activity of AlstR-expressing excitatory and inhibitory neurons in response to intrasomatic current injections and laser photostimulation via glutamate uncaging, but control neurons without AlstR expression were not affected. As for the cortical network activity, the peptide application constrained photostimulation-evoked excitatory activity propagation detected by fast voltage-sensitive dye (VSD) imaging of the slices expressing AlstRs selectively in excitatory neurons, while it augmented excitatory activity in those slices with inhibitory neurons expressing AlstRs. In addition, AlstR-mediated inactivation effectively suppressed pharmacologically induced seizure activity in the slices targeting AlstRs to excitatory neurons. Taken together, our work demonstrated that the genetic delivery of AlstRs can be used for regulation of cortical excitability in a cell-type specific manner, and suggested that the AlstR system can be potentially used for fast seizure control.

Mapping inhibitory neuronal circuits by laser scanning photostimulation

Inhibitory neurons are crucial to cortical function. They comprise about 20% of the entire cortical neuronal population and can be further subdivided into diverse subtypes based on their immunochemical, morphological, and physiological properties. Although previous research has revealed much about intrinsic properties of individual types of inhibitory neurons, knowledge about their local circuit connections is still relatively limited. Given that each individual neuron's function is shaped by its excitatory and inhibitory synaptic input within cortical circuits, we have been using laser scanning photostimulation (LSPS) to map local circuit connections to specific inhibitory cell types. Compared to conventional electrical stimulation or glutamate puff stimulation, LSPS has unique advantages allowing for extensive mapping and quantitative analysis of local functional inputs to individually recorded neurons. Laser photostimulation via glutamate uncaging selectively activates neurons perisomatically, without activating axons of passage or distal dendrites, which ensures a sub-laminar mapping resolution. The sensitivity and efficiency of LSPS for mapping inputs from many stimulation sites over a large region are well suited for cortical circuit analysis. Here we introduce the technique of LSPS combined with whole-cell patch clamping for local inhibitory circuit mapping. Targeted recordings of specific inhibitory cell types are facilitated by use of transgenic mice expressing green fluorescent proteins (GFP) in limited inhibitory neuron populations in the cortex, which enables consistent sampling of the targeted cell types and unambiguous identification of the cell types recorded. As for LSPS mapping, we outline the system instrumentation, describe the experimental procedure and data acquisition, and present examples of circuit mapping in mouse primary somatosensory cortex. As illustrated in our experiments, caged glutamate is activated in a spatially restricted region of the brain slice by UV laser photolysis; simultaneous voltage-clamp recordings allow detection of photostimulation-evoked synaptic responses. Maps of either excitatory or inhibitory synaptic input to the targeted neuron are generated by scanning the laser beam to stimulate hundreds of potential presynaptic sites. Thus, LSPS enables the construction of detailed maps of synaptic inputs impinging onto specific types of inhibitory neurons through repeated experiments. Taken together, the photostimulation-based technique offers neuroscientists a powerful tool for determining the functional organization of local cortical circuits.

High precision and fast functional mapping of cortical circuitry through a novel combination of voltage sensitive dye imaging and laser scanning photostimulation

The development of modern neuroscience tools is critical for deciphering brain circuit organization and function. An important aspect for technical development is to enhance each technique's advantages and compensate for limitations. We developed a high-precision and fast functional mapping technique in brain slices that incorporates the spatial precision of activation that can be achieved by laser-scanning photostimulation with rapid and high-temporal resolution assessment of evoked network activity that can be achieved by voltage-sensitive dye imaging. Unlike combination of whole cell recordings with photostimulation for mapping local circuit inputs to individually recorded neurons, this innovation is a new photostimulation-based technique to map cortical circuit output and functional connections at the level of neuronal populations. Here we report on this novel technique in detail and show its effective applications in mapping functional connections and circuit dynamics in mouse primary visual cortex and hippocampus. Given that this innovation enables rapid mapping and precise evaluation of cortical organization and function, it can have broad impacts in the field of cortical circuitry.

Evaluation of channel function after alteration of amino acid residues at the pore center of KCNQ1 channel

The effect of the electrical charge or the size of the amino acid residue at the pore center of a slowly activation component of the delayed rectifier potassium channel: KCNQ1 was studied. K(+) currents were measured after transfection of one of four KCNQ1 mutants: substituting Isoleucine with Lysine, Glutamate, Valine or Glycine and then transfected in COS-7 cells. Both the negatively- and positive charged residue I313K and I313E showed a loss of function when expressed alone and a dominant negative suppression when co-expressed with wild type KCNQ1. When the site was substituted with the smallest neutral amino acid residue: I313G, there was a small reduction of current when transfected alone and a gain of function when co-transfected with the wild type. I313V showed no difference from the wild type. Changes of amino acid residue at the pore center of KCNQ1 may alter the channel function but this depends on the electrical charge or the size of amino acid residue.

A pilot-controlled study of myeloperoxidase-specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA) in the coronary circulation

Hereby we report our observations derived from a pilot-study of 39 subjects (30 patients with coronary artery disease [CAD] and 9 non-CAD controls). In this work, we aimed to evaluate MPO-ANCA titer in the human coronary circulation for the first time; and examine its possible association with CAD and some cytokines/inflammatory markers. We found higher mean coronary MPO-ANCA titer in CAD subjects than in non-CAD controls; beside significant positive correlations between MPO-ANCA titers and both C-reactive protein and interleukin-6 levels. Thus, we might suggest the possible involvement of MPO-ANCA in coronary atherogenesis indirectly through modulating some pro-inflammatory cytokines/markers; that a large-scale study of MPO-ANCA in CAD patients may be warranted in the future.

A double-point mutation in the selectivity filter site of the KCNQ1 potassium channel results in a severe phenotype, LQT1, of long QT syndrome

INTRODUCTION

Slowly activating delayed-rectifier potassium currents in the heart are produced by a complex protein with alpha and beta subunits composed of the potassium voltage-gated channel KQT-like subfamily, member 1 (KCNQ1) and the potassium voltage-gated channel Isk-related family, member 1 (KCNE1), respectively. Mutations in KCNQ1 underlie the most common type of hereditary long QT syndrome (LQTS). Like other potassium channels, KCNQ1 has six transmembrane domains and a highly conserved potassium selectivity filter in the pore helix called "the signature sequence." We aimed to investigate the functional consequences of a newly identified mutation within the signature sequence.

METHODS AND RESULTS

Potassium channel genomic DNA from a family with clinical evidence of LQTS was amplified by polymerase chain reaction (PCR), and the resulting products were then sequenced. Three family members had a double-point mutation in KCNQ1 at nucleotides 938 (T-to-A) and 939 (C-to-A), resulting in an isoleucine-to-lysine change at amino acid position 313. These patients displayed prolonged QTc intervals (629, 508, and 500 ms(1/2,) respectively) and repetitive episodes of syncope, but no deafness. Three-dimensional structure modeling of KCNQ1 revealed that this mutation is located at the center of the channel pore. COS-7 cells displayed a lack of current when transfected with a plasmid expressing the mutant. In addition, the mutant displayed a dominant negative effect on current but appeared normal with respect to plasma membrane integration.

CONCLUSION

An I313K mutation within the selectivity filter of KCNQ1 results in a dominant-negative loss of channel function, leading to a long QT interval and subsequent syncope.

Impact of percutaneous coronary intervention on the levels of interleukin-6 and C-reactive protein in the coronary circulation of subjects with coronary artery disease

Many clinical studies have evaluated the inflammatory response (mainly interleukin [IL]-6 and C-reactive protein [CRP]) after percutaneous coronary intervention (PCI) in patients with coronary artery disease (CAD). The aim of this study was to verify the source of possible elevation of IL-6 and CRP after PCI using coronary sinus sampling. We studied 87 subjects who underwent coronary angiography for diagnostic, therapeutic, or follow-up purposes. Blood samples were taken by the PCI team during the catheterization study from the coronary sinus. We measured coronary IL-6 levels by sandwich enzyme-linked immunosorbent assay, and high-sensitivity CRP levels were measured by latex immunonephelometry. The subjects were then classified according to their coronary angiographic findings into non-CAD (no evidence of significant organic CAD), mild CAD (1 vessel narrowed), and severe CAD (>or=2 vessels narrowed) groups. PCI (including stent deployment) was performed in 16 patients with CAD. The mean coronary IL-6 value was higher in the severe than in the mild CAD group (3.67 +/- 2.48 vs 2.3 +/- 1.15 pg/ml, p = 0.027). The mean coronary IL-6 value was higher in the subjects who underwent PCI than in those who did not (2.9 +/- 1.23 vs 1.87 +/- 0.9 pg/ml, p = 0.037), and the same was found regarding CRP (1.244 +/- 0.72 vs 0.498 +/- 0.51 mg/L, p = 0.032). The coronary IL-6 values correlated positively with the coronary CRP values (r = 0.374, p = 0.017). In conclusion, the increase in coronary IL-6 and CRP levels after PCI in patients with CAD might be attributed to their release from the coronary atheroma secondary to the direct mechanical effect applied on the atheroma itself by balloon inflation and stent deployment.

Human cardiac ryanodine receptor mutations in ion channel disorders in Japan

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterized by adrenergic induced bidirectional or polymorphic ventricular tachycardias. Some of CPVT families were reported to be associated with cardiac ryanodine receptor gene (RyR2) mutations. However, association between RyR2 and other arrhythmogenic disorders is not clarified. In this study, we analyzed 83 Japanese patients including patients with long-QT syndrome, Brugada syndrome, idiopathic ventricular fibrillation, arrhythmogenic right ventricular cardiomyopathy and CPVT. Genetic screening of RyR2 revealed 3 distinct mutations among 4 families with CPVT (75% of incidence). However, no mutation was found in other groups. This is the first report to demonstrate prevalence of RyR2 mutations in various arrhythmogenic disorders in Japan. RyR2 mutations were detected frequently in CPVT but not in other diseases.