Natural killer T cells in allergic asthma: implications for the development of novel immunotherapeutical strategies.

Allergic asthma has emerged as a prevalent allergic disease worldwide, affecting most prominently both young individuals and lower-income populations in developing and developed countries. To devise effective and curative immunotherapy, it is crucial to comprehend the intricate nature of this condition, characterized by an immune response imbalance that favors a proinflammatory profile orchestrated by diverse subsets of immune cells. Although the involvement of Natural Killer T (NKT) cells in asthma pathology is frequently implied, their specific contributions to disease onset and progression remain incompletely understood. Given their remarkable ability to modulate the immune response through the rapid secretion of various cytokines, NKT cells represent a promising target for the development of effective immunotherapy against allergic asthma. This review provides a comprehensive summary of the current understanding of NKT cells in the context of allergic asthma, along with novel therapeutic approaches that leverage the functional response of these cells.

Targeting VCAM-1: a therapeutic opportunity for vascular damage.

INTRODUCTION: The vascular cell adhesion molecule (VCAM-1) is a transmembrane sialoglycoprotein detected in activated endothelial and vascular smooth muscle cells involved in the adhesion and transmigration of inflammatory cells into damaged tissue. Widely used as a pro-inflammatory marker, its potential role as a targeting molecule has not been thoroughly explored. AREAS COVERED: We discuss the current evidence supporting the potential targeting of VCAM-1 in atherosclerosis, diabetes, hypertension and ischemia/reperfusion injury. EXPERT OPINION: There is emerging evidence that VCAM-1 is more than a biomarker and may be a promising therapeutic target for vascular diseases. While there are neutralizing antibodies that allow preclinical research, the development of pharmacological tools to activate or inhibit this protein are required to thoroughly assess its therapeutic potential.

Mitochondria and Calcium Regulation as Basis of Neurodegeneration Associated With Aging.

Age is the main risk factor for the onset of neurodegenerative diseases. A decline of mitochondrial function has been observed in several age-dependent neurodegenerative diseases and may be a major contributing factor in their progression. Recent findings have shown that mitochondrial fitness is tightly regulated by Ca2+ signals, which are altered long before the onset of measurable histopathology hallmarks or cognitive deficits in several neurodegenerative diseases including Alzheimer's disease (AD), the most frequent cause of dementia. The transfer of Ca2+ from the endoplasmic reticulum (ER) to the mitochondria, facilitated by the presence of mitochondria-associated membranes (MAMs), is essential for several physiological mitochondrial functions such as respiration. Ca2+ transfer to mitochondria must be finely regulated because excess Ca2+ will disturb oxidative phosphorylation (OXPHOS), thereby increasing the generation of reactive oxygen species (ROS) that leads to cellular damage observed in both aging and neurodegenerative diseases. In addition, excess Ca2+ and ROS trigger the opening of the mitochondrial transition pore mPTP, leading to loss of mitochondrial function and cell death. mPTP opening probably increases with age and its activity has been associated with several neurodegenerative diseases. As Ca2+ seems to be the initiator of the mitochondrial failure that contributes to the synaptic deficit observed during aging and neurodegeneration, in this review, we aim to look at current evidence for mitochondrial dysfunction caused by Ca2+ miscommunication in neuronal models of neurodegenerative disorders related to aging, with special emphasis on AD.

Calcium release by ryanodine receptors mediates hydrogen peroxide-induced activation of ERK and CREB phosphorylation in N2a cells and hippocampal neurons.

Hydrogen peroxide, which stimulates ERK phosphorylation and synaptic plasticity in hippocampal neurons, has also been shown to stimulate calcium release in muscle cells by promoting ryanodine receptor redox modification (S-glutathionylation). We report here that exposure of N2a cells or rat hippocampal neurons in culture to 200 microM H2O2 elicited calcium signals, increased ryanodine receptor S-glutathionylation, and enhanced both ERK and CREB phosphorylation. In mouse hippocampal slices, H2O2 (1 microM) also stimulated ERK and CREB phosphorylation. Preincubation with ryanodine (50 microM) largely prevented the effects of H2O2 on calcium signals and ERK/CREB phosphorylation. In N2a cells, the ERK kinase inhibitor U0126 suppressed ERK phosphorylation and abolished the stimulation of CREB phosphorylation produced by H2O2, suggesting that H2O2 enhanced CREB phosphorylation via ERK activation. In N2a cells in calcium-free media, 200 microM H2O2 stimulated ERK and CREB phosphorylation, while preincubation with thapsigargin prevented these enhancements. These combined results strongly suggest that H2O2 promotes ryanodine receptors redox modification; the resulting calcium release signals, by enhancing ERK activity, would increase CREB phosphorylation. We propose that ryanodine receptor stimulation by activity-generated redox species produces calcium release signals that may contribute significantly to hippocampal synaptic plasticity, including plasticity that requires long-lasting ERK-dependent CREB phosphorylation.

Depolarization of skeletal muscle cells induces phosphorylation of cAMP response element binding protein via calcium and protein kinase Calpha.

Membrane depolarization of skeletal muscle cells induces slow inositol trisphosphate-mediated calcium signals that regulate the activity of transcription factors such as the cAMP-response element-binding protein (CREB), jun, and fos. Here we investigated whether such signals regulate CREB phosphorylation via protein kinase C (PKC)-dependent pathways. Western blot analysis revealed the presence of seven isoforms (PKCalpha, -betaI, -betaII, -delta, -epsilon, -, and -zeta) in rat primary myotubes. The PKC inhibitors bisindolymaleimide I and Gö6976, blocked CREB phosphorylation. Chronic exposure to phorbol ester triggered complete down-regulation of several isoforms, but reduced PKCalpha levels to only 40%, and did not prevent CREB phosphorylation upon myotube depolarization. Immunocytochemical analysis revealed selective and rapid PKCalpha translocation to the nucleus following depolarization, which was blocked by 2-amino-ethoxydiphenyl borate, an inositol trisphosphate receptor inhibitor, and by the phospholipase C inhibitor U73122. In C2C12 cells, which expressed PKCalpha,-epsilon, and -zeta, CREB phosphorylation also depended on PKCalpha. These results strongly implicate nuclear PKCalpha translocation in CREB phosphorylation induced by skeletal muscle membrane depolarization.

Testosterone stimulates intracellular calcium release and mitogen-activated protein kinases via a G protein-coupled receptor in skeletal muscle cells.

Involvement of intracellular Ca(2+) and ERK1/2 phosphorylation in the fast nongenomic effects of androgens in myotubes was investigated. Testosterone or nandrolone produced fast (<1 min) and transient increases in intracellular Ca(2+) with an oscillatory pattern. Calcium signals were slightly reduced in Ca(2+)-free medium, but lack of oscillations was evident. Signals were blocked by U-73122 and xestospongin B, inhibitors of inositol 1,4,5-trisphosphate (IP(3)) pathway. Furthermore, IP(3) increased transiently 2- to 3-fold 45 sec after hormone addition. Cyproterone neither affected the fast Ca(2+) signal nor the increase in IP(3). Calcium increases could also be induced by the impermeant testosterone conjugated to BSA, and the effect of testosterone was abolished in cells incubated with guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin. Stimulation of myotubes with testosterone, nandrolone, or testosterone conjugated to BSA increased immunodetectable phosphorylation of ERK1/2 within 5 min, and this effect was not inhibited by cyproterone. Phosphorylation was blocked by the use of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethylester, U-73122, and xestospongin B as well as by dominant negative Ras, MAPK kinase (MEK), or the MEK inhibitor PD-98059. In addition, guanosine 5'-O-(2-thiodiphosphate) or pertussis toxin blocked ERK1/2 phosphorylation. These results are consistent with a fast effect of testosterone, involving a G protein-linked receptor at the plasma membrane, IP(3)-mediated Ca(2+) signal, and the Ras/MEK/ERK pathway in muscle cells.

Depolarization-induced slow calcium transients activate early genes in skeletal muscle cells.

The signaling mechanisms by which skeletal muscle electrical activity leads to changes in gene expression remain largely undefined. We have reported that myotube depolarization induces calcium signals in the cytosol and nucleus via inositol 1,4,5-trisphosphate (IP(3)) and phosphorylation of both ERK1/2 and cAMP-response element-binding protein (CREB). We now describe the calcium dependence of P-CREB and P-ERK induction and of the increases in mRNA of the early genes c-fos, c-jun, and egr-1. Increased phosphorylation and early gene activation were maintained in the absence of extracellular calcium, while the increase in intracellular calcium induced by caffeine could mimic the depolarization stimulus. Depolarization performed either in the presence of the IP(3) inhibitors 2-aminoethoxydiphenyl borate or xestospongin C or on cells loaded with BAPTA-AM, in which slow calcium signals were abolished, resulted in decreased activation of the early genes examined. Both early gene activation and CREB phosphorylation were inhibited by ERK phosphorylation blockade. These data suggest a role for calcium in the transcription-related events that follow membrane depolarization in muscle cells.