Rescue of Normal Excitability in LGI1-Deficient Epileptic Neurons.

Leucine-rich glioma inactivated 1 (LGI1) is a glycoprotein secreted by neurons, the deletion of which leads to autosomal dominant lateral temporal lobe epilepsy. We previously showed that LGI1 deficiency in a mouse model (i.e., knock-out for LGI1 or KO-Lgi1) decreased Kv1.1 channel density at the axon initial segment (AIS) and at presynaptic terminals, thus enhancing both intrinsic excitability and glutamate release. However, it is not known whether normal excitability can be restored in epileptic neurons. Here, we show that the selective expression of LGI1 in KO-Lgi1 neurons from mice of both sexes, using single-cell electroporation, reduces intrinsic excitability and restores both the Kv1.1-mediated D-type current and Kv1.1 channels at the AIS. In addition, we show that the homeostatic-like shortening of the AIS length observed in KO-Lgi1 neurons is prevented in neurons electroporated with the Lgi1 gene. Furthermore, we reveal a spatial gradient of intrinsic excitability that is centered on the electroporated neuron. We conclude that expression of LGI1 restores normal excitability through functional Kv1 channels at the AIS.SIGNIFICANCE STATEMENT The lack of leucine-rich glioma inactivated 1 (LGI1) protein induces severe epileptic seizures that leads to death. Enhanced intrinsic and synaptic excitation in KO-Lgi1 mice is because of the decrease in Kv1.1 channels in CA3 neurons. However, the conditions to restore normal excitability profile in epileptic neurons remain to be defined. We show here that the expression of LGI1 in KO-Lgi1 neurons in single neurons reduces intrinsic excitability, and restores both the Kv1.1-mediated D-type current and Kv1.1 channels at the axon initial segment (AIS). Furthermore, the homeostatic shortening of the AIS length observed in KO-Lgi1 neurons is prevented in neurons in which the Lgi1 gene has been rescued. We conclude that LGI1 constitutes a critical factor to restore normal excitability in epileptic neurons.

Contribution of Axon Initial Segment Structure and Channels to Brain Pathology.

Brain channelopathies are a group of neurological disorders that result from genetic mutations affecting ion channels in the brain. Ion channels are specialized proteins that play a crucial role in the electrical activity of nerve cells by controlling the flow of ions such as sodium, potassium, and calcium. When these channels are not functioning properly, they can cause a wide range of neurological symptoms such as seizures, movement disorders, and cognitive impairment. In this context, the axon initial segment (AIS) is the site of action potential initiation in most neurons. This region is characterized by a high density of voltage-gated sodium channels (VGSCs), which are responsible for the rapid depolarization that occurs when the neuron is stimulated. The AIS is also enriched in other ion channels, such as potassium channels, that play a role in shaping the action potential waveform and determining the firing frequency of the neuron. In addition to ion channels, the AIS contains a complex cytoskeletal structure that helps to anchor the channels in place and regulate their function. Therefore, alterations in this complex structure of ion channels, scaffold proteins, and specialized cytoskeleton may also cause brain channelopathies not necessarily associated with ion channel mutations. This review will focus on how the AISs structure, plasticity, and composition alterations may generate changes in action potentials and neuronal dysfunction leading to brain diseases. AIS function alterations may be the consequence of voltage-gated ion channel mutations, but also may be due to ligand-activated channels and receptors and AIS structural and membrane proteins that support the function of voltage-gated ion channels.

Pericarditis efusivo-constrictiva recidivante tras COVID-19 / Recurrent Pericarditis After Covid-19

Paciente con artritis reumatoide que tiene COVID-19 con debut de pericaditis recidivante, diagnóstico diferencial.(AU)

Patient with rheumatoid arthritis who has Covid-19 with recurrent pericaditis debut, differential diagnosis.(AU)

Prospective multicentre study of experience in real-world clinical practice in monitoring reported outcome measures (PROMs) of patient with a diagnosis of psoriatic and/or spondyloarthritis and initiating treatment with secukinumab.

OBJECTIVE: To analyse the effect of secukinumab on self-reported variables of patients diagnosed with psoriatic arthritis and/or ankylosing spondylitis in relation to their health status, pain, fatigue, sleep and quality of life. METHODS: A six-month, observational, longitudinal, prospective, multicentre study was conducted with 39 patients who initiated treatment with secukinumab as therapy for psoriatic arthritis and/or spondylitis. The main variables were changes in patient-reported measures and they were evaluated by means of the questionnaires: FACIT-fatigue, Insomnia Severity Index, EuroQol-3L-5D and PsAQoL. In addition, depending on the type of disease (peripheral psoriasis or spondyloarthritis) the DAS28 with ESR or the BASDAI were calculated, respectively. RESULTS: Levels of fatigue, moderate and severe insomnia significantly reduced after 6 months of treatment with secukinumab. At the same time, patient-reported quality of life increased significantly (P = .006). Data on pain and discomfort also show significant improvement after the treatment. CONCLUSIONS: Patients with psoriatic arthritis and/or ankylosing spondylitis who start treatment with secukinumab show improvement at 6 months in all effect sizes of the treatment, particularly in sleep, fatigue and quality of life. Furthermore, patient-reported outcome measures are of additional clinical value and allow more accurate and closer assessment of their real status of health and well-being.

Estudio prospectivo multicéntrico de experiencia en práctica clínica real en el control de medidas de desenlace reportadas por el paciente (PRO) diagnosticado de artritis psoriásica y/o espondiloartritis y que inicia tratamiento con secukinumab / Prospective multicentre study of experience in real-world clinical practice in monitoring reported outcome measures (PROMs) of patient with a diagnosis of psoriatic and/or spondyloarthritis and initiating treatment with secukinumab

Objetivo: Analizar el efecto del secukinumab sobre las variables propias reportadas por el paciente diagnosticado de artritis psoriásica y/o espondilitis anquilosante en relación con su estado de salud, dolor, fatiga, sueño y calidad de vida. Métodos: Se realizó un estudio observacional, longitudinal, prospectivo y multicéntrico a 6meses con 39 pacientes que iniciaron tratamiento con secukinumab para la terapia de artritis psoriásica y/o espondilitis. Las variables principales fueron los cambios en las medidas reportadas por el paciente, evaluándolas por medio de los cuestionarios FACIT-fatiga, Índice de Gravedad del Insomnio, EuroQol-3L-5D y PsAQoL. Adicionalmente, y dependiendo del tipo de enfermedad (psoriásica periférica o espondiloartritis), se recogió el DAS28 con velocidad o el BASDAI, respectivamente. Resultados: Los niveles de fatiga, insomnio moderado y grave presentan una reducción significativa tras el tratamiento de 6meses con secukinumab. Al mismo tiempo, la calidad de vida reportada por el paciente aumenta notablemente (p=0,006). Los datos referentes al dolor y a la incomodidad también presentan una notable mejoría tras el tratamiento. Conclusiones: Los pacientes de artritis psoriásica y/o espondilitis anquilosante que inician tratamiento con secukinumab presentan mejoría a los 6meses en todos los tamaños del efecto del tratamiento, particularmente en el sueño, la fatiga y la calidad de vida. Además, las medidas de desenlace reportadas por los pacientes son un valor clínico adicional y permiten realizar una valoración más exacta y aproximada de su estado real de salud y bienestar.(AU)

Objective: To analyse the effect of secukinumab on self-reported variables of patients diagnosed with psoriatic arthritis and/or ankylosing spondylitis in relation to their health status, pain, fatigue, sleep and quality of life. Methods: A six-month, observational, longitudinal, prospective, multicentre study was conducted with 39 patients who initiated treatment with secukinumab as therapy for psoriatic arthritis and/or spondylitis. The main variables were changes in patient-reported measures and they were evaluated by means of the questionnaires: FACIT-fatigue, Insomnia Severity Index, EuroQol-3L-5D and PsAQoL. In addition, depending on the type of disease (peripheral psoriasis or spondyloarthritis) the DAS28 with ESR or the BASDAI were calculated, respectively. Results: Levels of fatigue, moderate and severe insomnia significantly reduced after 6months of treatment with secukinumab. At the same time, patient-reported quality of life increased significantly (P=.006). Data on pain and discomfort also show significant improvement after the treatment. Conclusions: Patients with psoriatic arthritis and/or ankylosing spondylitis who start treatment with secukinumab show improvement at 6months in all effect sizes of the treatment, particularly in sleep, fatigue and quality of life. Furthermore, patient-reported outcome measures are of additional clinical value and allow more accurate and closer assessment of their real status of health and well-being.(AU)

Recurrent pericarditis after Covid-19.

Patient with rheumatoid arthritis who has Covid-19 with recurrent pericaditis debut, differential diagnosis.

Homeostatic regulation of axonal Kv1.1 channels accounts for both synaptic and intrinsic modifications in the hippocampal CA3 circuit.

Homeostatic plasticity of intrinsic excitability goes hand in hand with homeostatic plasticity of synaptic transmission. However, the mechanisms linking the two forms of homeostatic regulation have not been identified so far. Using electrophysiological, imaging, and immunohistochemical techniques, we show here that blockade of excitatory synaptic receptors for 2 to 3 d induces an up-regulation of both synaptic transmission at CA3-CA3 connections and intrinsic excitability of CA3 pyramidal neurons. Intrinsic plasticity was found to be mediated by a reduction of Kv1.1 channel density at the axon initial segment. In activity-deprived circuits, CA3-CA3 synapses were found to express a high release probability, an insensitivity to dendrotoxin, and a lack of depolarization-induced presynaptic facilitation, indicating a reduction in presynaptic Kv1.1 function. Further support for the down-regulation of axonal Kv1.1 channels in activity-deprived neurons was the broadening of action potentials measured in the axon. We conclude that regulation of the axonal Kv1.1 channel constitutes a major mechanism linking intrinsic excitability and synaptic strength that accounts for the functional synergy existing between homeostatic regulation of intrinsic excitability and synaptic transmission.

Formin Activity and mDia1 Contribute to Maintain Axon Initial Segment Composition and Structure.

The axon initial segment (AIS) is essential for maintaining neuronal polarity, modulating protein transport into the axon, and action potential generation. These functions are supported by a distinctive actin and microtubule cytoskeleton that controls axonal trafficking and maintains a high density of voltage-gated ion channels linked by scaffold proteins to the AIS cytoskeleton. However, our knowledge of the mechanisms and proteins involved in AIS cytoskeleton regulation to maintain or modulate AIS structure is limited. In this context, formins play a significant role in the modulation of actin and microtubules. We show that pharmacological inhibition of formins modifies AIS actin and microtubule characteristics in cultured hippocampal neurons, reducing F-actin density and decreasing microtubule acetylation. Moreover, formin inhibition diminishes sodium channels, ankyrinG and ßIV-spectrin AIS density, and AIS length, in cultured neurons and brain slices, accompanied by decreased neuronal excitability. We show that genetic downregulation of the mDia1 formin by interference RNAs also decreases AIS protein density and shortens AIS length. The ankyrinG decrease and AIS shortening observed in pharmacologically inhibited neurons and neuron-expressing mDia1 shRNAs were impaired by HDAC6 downregulation or EB1-GFP expression, known to increase microtubule acetylation or stability. However, actin stabilization only partially prevented AIS shortening without affecting AIS protein density loss. These results suggest that mDia1 maintain AIS composition and length contributing to the stability of AIS microtubules.

Recurrent Pericarditis After Covid-19. / Pericarditis efusivo-constrictiva recidivante tras COVID-19.

Patient with rheumatoid arthritis who has Covid-19 with recurrent pericaditis debut, differential diagnosis.

Prospective multicentre study of experience in real-world clinical practice in monitoring reported outcome measures (PROMs) of patient with a diagnosis of psoriatic and/or spondyloarthritis and initiating treatment with secukinumab. / Estudio prospectivo multicéntrico de experiencia en práctica clínica real en el control de medidas de desenlace reportadas por el paciente (PRO) diagnosticado de artritis psoriásica y/o espondiloartritis y que inicia tratamiento con secukinumab.

OBJECTIVE: To analyse the effect of secukinumab on self-reported variables of patients diagnosed with psoriatic arthritis and/or ankylosing spondylitis in relation to their health status, pain, fatigue, sleep and quality of life. METHODS: A six-month, observational, longitudinal, prospective, multicentre study was conducted with 39 patients who initiated treatment with secukinumab as therapy for psoriatic arthritis and/or spondylitis. The main variables were changes in patient-reported measures and they were evaluated by means of the questionnaires: FACIT-fatigue, Insomnia Severity Index, EuroQol-3L-5D and PsAQoL. In addition, depending on the type of disease (peripheral psoriasis or spondyloarthritis) the DAS28 with ESR or the BASDAI were calculated, respectively. RESULTS: Levels of fatigue, moderate and severe insomnia significantly reduced after 6months of treatment with secukinumab. At the same time, patient-reported quality of life increased significantly (P=.006). Data on pain and discomfort also show significant improvement after the treatment. CONCLUSIONS: Patients with psoriatic arthritis and/or ankylosing spondylitis who start treatment with secukinumab show improvement at 6months in all effect sizes of the treatment, particularly in sleep, fatigue and quality of life. Furthermore, patient-reported outcome measures are of additional clinical value and allow more accurate and closer assessment of their real status of health and well-being.

Functional screenings reveal different requirements for host microRNAs in Salmonella and Shigella infection.

MicroRNAs (miRNAs) are increasingly recognized for their role in infection by bacterial pathogens, although the effect of each individual miRNA remains largely unknown. Here, we used a comparative genome-wide microscopy-based functional screening approach to identify miRNAs controlling infection by two bacterial pathogens-Salmonella enterica serovar Typhimurium and Shigella flexneri. Despite the similarities between these pathogens, we found infections to be controlled by largely non-overlapping subsets of miRNAs, seemingly reflecting different requirements prompted by their distinct intracellular lifestyles. By characterizing a small subset of miRNAs chosen among the strongest inhibitors of Shigella infection, we discovered that miR-3668, miR-4732-5p and miR-6073 exert a selective effect on Shigella infection by impairing bacterial actin-based motility by downregulating N-WASP. Additionally, by identifying let-7i-3p miRNA as a strong inhibitor of Salmonella replication and performing in-depth analysis of its mechanisms of action, we showed that this miRNA specifically inhibits Salmonella infection via modulation of endolysosomal trafficking and the vacuolar environment by targeting the host RGS2 protein. These findings illustrate two paradigms underlying miRNA-mediated regulation of bacterial infection, acting as part of the host response to infection, or as part of bacterial strategies to modulate the host environment and favour pathogenesis.

P2Y1 Purinergic Receptor Modulate Axon Initial Segment Initial Development.

Morphological and functional polarization of neurons depends on the generation and maintenance of the axon initial segment (AIS). This axonal domain maintains axonal properties but is also the place where the action potential (AP) is generated. All these functions require the AIS, a complex structure that is not fully understood. An integrated structure of voltage-gated ion channels, specific cytoskeleton architecture, as well as, scaffold proteins contributes to these functions. Among them, ankyrinG plays a crucial role to maintain ion channels and membrane proteins. However, it is still elusive how the AIS performs its complex structural and functional regulation. Recent studies reveal that AIS is dynamically regulated in molecular composition, length and location in response to neuronal activity. Some mechanisms acting on AIS plasticity have been uncovered recently, including Ca2+, calpain or calmodulin-mediated modulation, as well as post-translational modifications of cytoskeleton proteins and actin-associated proteins. Neurons are able to respond to different kind of physiological and pathological stimuli from development to maturity by adapting their AIS composition, position and length. This raises the question of which are the neuronal receptors that contribute to the modulation of AIS plasticity. Previous studies have shown that purinergic receptor P2X7 activation is detrimental to AIS maintenance. During initial axonal elongation, P2X7 is coordinated with P2Y1, another purinergic receptor that is essential for proper axon elongation. In this study, we focus on the role of P2Y1 receptor on AIS development and maintenance. Our results show that P2Y1 receptor activity and expression are necessary during AIS initial development, while has no role once AIS maturity is achieved. P2Y1 inhibition or suppression results in a decrease in ankyrinG, ßIV-spectrin and voltage-gated sodium channels accumulation that can be rescued by actin stabilization or the modulation of actin-binding proteins at the AIS. Moreover, P2X7 or calpain inhibition also rescues ankyrinG decrease. Hence, a dynamic balance of P2Y1 and P2X7 receptors expression and function during AIS assembly and maturation may represent a fine regulatory mechanism in response to physiological or pathological extracellular purines concentration.

Primary neurons can enter M-phase.

Differentiated neurons can undergo cell cycle re-entry during pathological conditions, but it remains largely accepted that M-phase is prohibited in these cells. Here we show that primary neurons at post-synaptogenesis stages of development can enter M-phase. We induced cell cycle re-entry by overexpressing a truncated Cyclin E isoform fused to Cdk2. Cyclin E/Cdk2 expression elicits canonical cell cycle checkpoints, which arrest cell cycle progression and trigger apoptosis. As in mitotic cells, checkpoint abrogation enables cell cycle progression through S and G2-phases into M-phase. Although most neurons enter M-phase, only a small subset undergo cell division. Alternatively, neurons can exit M-phase without cell division and recover the axon initial segment, a structural determinant of neuronal viability. We conclude that neurons and mitotic cells share S, G2 and M-phase regulation.

LGI1 tunes intrinsic excitability by regulating the density of axonal Kv1 channels.

Autosomal dominant epilepsy with auditory features results from mutations in leucine-rich glioma-inactivated 1 (LGI1), a soluble glycoprotein secreted by neurons. Animal models of LGI1 depletion display spontaneous seizures, however, the function of LGI1 and the mechanisms by which deficiency leads to epilepsy are unknown. We investigated the effects of pure recombinant LGI1 and genetic depletion on intrinsic excitability, in the absence of synaptic input, in hippocampal CA3 neurons, a classical focus for epileptogenesis. Our data indicate that LGI1 is expressed at the axonal initial segment and regulates action potential firing by setting the density of the axonal Kv1.1 channels that underlie dendrotoxin-sensitive D-type potassium current. LGI1 deficiency incurs a >50% down-regulation of the expression of Kv1.1 and Kv1.2 via a posttranscriptional mechanism, resulting in a reduction in the capacity of axonal D-type current to limit glutamate release, thus contributing to epileptogenesis.

The role of axonal Kv1 channels in CA3 pyramidal cell excitability.

Axonal ion channels control spike initiation and propagation along the axon and determine action potential waveform. We show here that functional suppression of axonal Kv1 channels with local puff of dendrotoxin (DTx), laser or mechanical axotomy significantly increased excitability measured in the cell body. Importantly, the functional effect of DTx puffing or axotomy was not limited to the axon initial segment but was also seen on axon collaterals. In contrast, no effects were observed when DTx was puffed on single apical dendrites or after single dendrotomy. A simple model with Kv1 located in the axon reproduced the experimental observations and showed that the distance at which the effects of axon collateral cuts are seen depends on the axon space constant. In conclusion, Kv1 channels located in the axon proper greatly participate in intrinsic excitability of CA3 pyramidal neurons. This finding stresses the importance of the axonal compartment in the regulation of intrinsic neuronal excitability.

Cannabinoid Receptors Modulate Neuronal Morphology and AnkyrinG Density at the Axon Initial Segment.

Neuronal polarization underlies the ability of neurons to integrate and transmit information. This process begins early in development with axon outgrowth, followed by dendritic growth and subsequent maturation. In between these two steps, the axon initial segment (AIS), a subcellular domain crucial for generating action potentials (APs) and maintaining the morphological and functional polarization, starts to develop. However, the cellular/molecular mechanisms and receptors involved in AIS initial development and maturation are mostly unknown. In this study, we have focused on the role of the type-1 cannabinoid receptor (CB1R), a highly abundant G-protein coupled receptor (GPCR) in the nervous system largely involved in different phases of neuronal development and differentiation. Although CB1R activity modulation has been related to changes in axons or dendrites, its possible role as a modulator of AIS development has not been yet explored. Here we analyzed the potential role of CB1R on neuronal morphology and AIS development using pharmacological and RNA interference approaches in cultured hippocampal neurons. CB1R inhibition, at a very early developmental stage, has no effect on axonal growth, yet CB1R activation can promote it. By contrast, subsequent dendritic growth is impaired by CB1R inhibition, which also reduces ankyrinG density at the AIS. Moreover, our data show a significant correlation between early dendritic growth and ankyrinG density. However, CB1R inhibition in later developmental stages after dendrites are formed only reduces ankyrinG accumulation at the AIS. In conclusion, our data suggest that neuronal CB1R basal activity plays a role in initial development of dendrites and indirectly in AIS proteins accumulation. Based on the lack of CB1R expression at the AIS, we hypothesize that CB1R mediated modulation of dendritic arbor size during early development indirectly determines the accumulation of ankyrinG and AIS development. Further studies will be necessary to determine which CB1R-dependent mechanisms can coordinate these two domains, and what may be the impact of these early developmental changes once neurons mature and are embedded in a functional brain network.

Class I PI3-kinase or Akt inhibition do not impair axonal polarization, but slow down axonal elongation.

PI3K proteins family have multiple and essential functions in most cellular events. This family is composed of class I, class II and class III PI3Ks, which upstream and downstream elements are not completely elucidated. Previous studies using the broad PI3K inhibitor, LY294002 allowed to propose that PI3 kinase>Akt pathway is a key element in the determination of axonal polarity in hippocampal neurons. Recently, new inhibitors with a higher selectivity for class I PI3K have been characterized. In the present study we have examined this widely accepted theory using a new class I PI3K inhibitor (GDC-0941), as well as Akt inhibitors, and PTEN phosphatase constructs to reduce PIP3 levels. Our present data show that both, class I PI3K inhibitor and Akt inhibitor did not alter axon specification in hippocampal neurons, but greatly reduced axon length. However, in the same experiments LY294002 effectively impeded axonal polarization, as previously reported. Our biochemical data show that both, class I PI3K and Akt inhibitors, effectively block downstream elements from Akt to S6K1 activity. Both inhibitors are stable in culture medium along the time period analysed, maintaining the inhibition better than LY294002. Besides, we found evidence that LY294002 directly inhibits mTORC1. However, further analysis using an mTORC1 inhibitor showed no change in neuron polarity. Same result was obtained using a general class III PI3K inhibitor. Interestingly, we found that either, wild-type PTEN, or a phosphatase-dead form of PTEN, disrupted axonal polarization, strongly suggesting that the role of PTEN in axonal polarity can be independent of PIP3.

RENACER study: Assessment of 12-month efficacy and safety of 168 certolizumab PEGol rheumatoid arthritis-treated patients from a Spanish multicenter national database.

OBJECTIVE: To assess effectiveness and safety of certolizumab PEGol (CZP) in rheumatoid arthritis (RA) patients after 12 months of treatment and to detect predictors of response. METHODS: Observational longitudinal prospective study of RA patients from 35 sites in Spain. Variables (baseline, 3- and 12-month assessment): sociodemographics, previous Disease Modifying Anti-Rheumatic Drug (DMARD) and previous Biological Therapies (BT) use; TJC, SJC, ESR, CRP, DAS28, SDAI. Response variables: TJC, SJC, CRP, ESR, and steroids dose reductions, EULAR Moderate/Good Response, SDAI response and remission, DAS28 remission. Safety variables: discontinuation due to side-effects. Descriptive, comparative and Logistic regression analyses were performed. RESULTS: We included 168 patients: 79.2% women, mean age 54.5 years (±13.2 SD), mean disease duration 7.5 years (±7.3 SD). Mean number of prior DMARD: 1.4 (±1.2 SD), mean number of prior BT was 0.8 (±1.1). Mean time on CZP was 9.8 months (±3.4 SD). A total of 71.4% were receiving CZP at 12-month assessment. Baseline predictors of response: lower prior number DMARD; low number prior BT; higher CRP, ESR, TJC, SJC, DAS28 and SDAI (p < 0.05) scores. A 25/46.4% Moderate/Good Response, a 20% SDAI remission, and a 44% DAS28 remission were observed. We observed 48 discontinuations (28.6%), 31 due to partial or complete ineffectiveness, and 17 due to side-effects. CONCLUSIONS: CZP showed benefit in severe RA patients, with significant reduction of all effectiveness parameters, despite the high prevalence of previous BT exposure in our series. We found CRP, ESR, prior DMARD/BT number, TJC, SJC, DAS28, and SDAI as baseline predictors of response. CZP was mostly well tolerated.

ATP-P2X7 Receptor Modulates Axon Initial Segment Composition and Function in Physiological Conditions and Brain Injury.

Axon properties, including action potential initiation and modulation, depend on both AIS integrity and the regulation of ion channel expression in the AIS. Alteration of the axon initial segment (AIS) has been implicated in neurodegenerative, psychiatric, and brain trauma diseases, thus identification of the physiological mechanisms that regulate the AIS is required to understand and circumvent AIS alterations in pathological conditions. Here, we show that the purinergic P2X7 receptor and its agonist, adenosine triphosphate (ATP), modulate both structural proteins and ion channel density at the AIS in cultured neurons and brain slices. In cultured hippocampal neurons, an increment of extracellular ATP concentration or P2X7-green fluorescent protein (GFP) expression reduced the density of ankyrin G and voltage-gated sodium channels at the AIS. This effect is mediated by P2X7-regulated calcium influx and calpain activation, and impaired by P2X7 inhibition with Brilliant Blue G (BBG), or P2X7 suppression. Electrophysiological studies in brain slices showed that P2X7-GFP transfection decreased both sodium current amplitude and intrinsic neuronal excitability, while P2X7 inhibition had the opposite effect. Finally, inhibition of P2X7 with BBG prevented AIS disruption after ischemia/reperfusion in rats. In conclusion, our study demonstrates an involvement of P2X7 receptors in the regulation of AIS mediated neuronal excitability in physiological and pathological conditions.

Proteomic approaches to study the pig intestinal system.

One of the major challenges in pig production is managing digestive health to maximize feed conversion and growth rates, but also to minimize treatment costs and to warrant public health. There is a great interest in the development of useful tools for intestinal health monitoring and the investigation of possible prophylactic/ therapeutic intervention pathways. A great variety of in vivo and in vitro intestinal models of study have been developed in the recent years. The understanding of such a complex system as the intestinal system (IS), and the study of its physiology and pathology is not an easy task. Analysis of such a complex system requires the use of systems biology techniques, like proteomics. However, for a correct interpretation of results and to maximize analysis performance, a careful selection of the IS model of study and proteomic platform is required. The study of the IS system is especially important in the pig, a species whose farming requires a very careful management of husbandry procedures regarding feeding and nutrition. The incorrect management of the pig digestive system leads directly to economic losses related suboptimal growth and feed utilization and/or the appearance of intestinal infections, in particular diarrhea. Furthermore, this species is the most suitable experimental model for human IS studies. Proteomics has risen as one of the most promising approaches to study the pig IS. In this review, we describe the most useful models of IS research in porcine and the different proteomic platforms available. An overview of the recent findings in pig IS proteomics is also provided.