Thymocyte expression of cathepsin L is essential for NKT cell development

CD1d antigen presentation to natural killer T (NKT) cells expressing the semi-invariant T cell receptor V(alpha)14J(alpha)18 requires CD1d trafficking through endosomal compartments; however, the endosomal events remain undefined. We show that mice lacking the endosomal protease cathepsin L (catL) have greatly reduced numbers of V(alpha)14(+)NK1.1(+) T cells. In addition, catL expression in thymocytes is critical not only for selection of these cells in vivo but also for stimulation of V(alpha)14(+)NK1.1(+) T cells in vitro. CD1d cell-surface expression and intracellular localization appear normal in catL-deficient thymocytes, as does the lysosomal morphology; this implies a specific role for catL in regulating presentation of natural CD1d ligands mediating V(alpha)14(+)NK1.1(+) T cell selection. These data implicate lysosomal proteases as key regulators of not only classical major histocompatibility complex class II antigen presentation but also nonclassical CD1d presentation.     

α7 Nicotinic Acetylcholine Receptor Regulates Airway Epithelium Differentiation by Controlling Basal Cell Proliferation

Airway epithelial basal cells are known to be critical for regenerating injured epithelium and maintaining tissue homeostasis. Recent evidence suggests that the α7 nicotinic acetylcholine receptor (nAChR), which is highly permeable to Ca²⁺, is involved in lung morphogenesis. Here, we have investigated the potential role of the α7 nAChR in the regulation of airway epithelial basal cell proliferation and the differentiation of the human airway epithelium. In vivo during fetal development and in vitro during the regeneration of the human airway epithelium, α7 nAChR expression coincides with epithelium differentiation. Inactivating α7 nAChR function in vitro increases cell proliferation during the initial steps of the epithelium regeneration, leading to epithelial alterations such as basal cell hyperplasia and squamous metaplasia, remodeling observed in many bronchopulmonary diseases. The regeneration of the airway epithelium after injury in α7^−/− mice is delayed and characterized by a transient hyperplasia of basal cells. Moreover, 1-year-old α7^−/− mice more frequently present basal cells hyperplasia. Modulating nAChR function or expression shows that only α7 nAChR, as opposed to heteropentameric α_xβ_y nAChRs, controls the proliferation of human airway epithelial basal cells. These findings suggest that α7 nAChR is a key regulator of the plasticity of the human airway epithelium by controlling basal cell proliferation and differentiation pathway and is involved in airway remodeling during bronchopulmonary diseases.The respiratory epithelium, which is constantly exposed to airborne pollutants, is frequently injured, which results in altered epithelial functions. To restore these functions, the respiratory epithelium must undergo rapid repair via epithelial cell spreading and migration and regenerate its structure via basal cell proliferation and differentiation.¹ These processes are tightly controlled to restore the pseudostratified architecture of the normal mucociliary epithelium. However, in most respiratory diseases, alterations of the regeneration processes induce epithelial remodeling such as hyperplasia, metaplasia, and fibrosis. Understanding the sequence of processes involved in cell proliferation and differentiation is therefore of crucial importance. Both in vivo and in vitro, human airway basal cells are able to proliferate and reconstitute a fully differentiated and functional epithelium.² These cells are such considered as progenitors of the human airway epithelium and important actors of the airway epithelium regeneration.The nonneuronal cholinergic system is thought to be involved in the regulation of cell functions such as cell-cell interaction, apoptosis, and proliferation.³ It is now established that human bronchial epithelial cells contain all of the machinery for the production, storage, secretion, and degradation of acetylcholine, which acts as an autocrine or paracrine hormone.^4,5 Acetylcholine exerts its effects through muscarinic and nicotinic acetylcholine receptors. Nicotinic acetylcholine receptors (nAChRs) are composed of five subunits, arranged as α/β heteromeric or α homomeric nAChRs, and assembled around a central ion channel, mediating the influx of Ca²⁺.⁶ The airway epithelium expresses α3, α4, α5, α7, α9, β2, and β4 subunits for nAChRs.^7,8,9α7 nAChR is characterized by an elevated Ca²⁺ permeability¹⁰ and has been involved in several important biological processes such as cell proliferation, apoptosis, and angiogenesis in cancer.^11,12 Prenatal nicotine exposure significantly increases pulmonary α7 nAChR expression and alters fetal lung development¹³ and subsequently pulmonary function in newborn.¹⁴ In particular, alteration of lung branching morphogenesis induced by nicotine is mediated by α7 nAChR.¹⁵ Altogether, these observations led us to investigate whether the α7 nAChR could be involved in the differentiation of the respiratory epithelium. In the human airway epithelium, we observed α7 nAChR expression in basal cells, which play a critical role in the epithelial regeneration. Both in vivo and in vitro, the α7 nAChR expression is associated with the airway epithelium differentiation. Moreover, in vitro inactivating α7 nAChR or in vivo disrupting genetic α7 nAChR expression induces airway epithelium remodeling by modulating basal cell proliferation. This study thus provides several lines of evidence that α7 nAChR is significant for airway epithelial differentiation and suggests that α7 nAChR is a key regulator of the plasticity of the airway epithelium.     

High-fat diet induced an oxidative stress in white adipose tissue and disturbed plasma transition metals in rat: prevention by grape seed and skin extract

Obesity is a public health problem characterized by increased accumulation of fat into adipose tissues leading to oxidative stress, dyslipidemia, and chronic inflammatory status. We used an experimental model of high-fat diet-induced obesity to analyze the link between dyslipidemia, oxidative stress, and fat accumulation into adipose tissue of rats, as well as the involvement of intracellular mediators such as transition metals on signal transduction. We also looked at the ability of a grape seed and skin extract (GSSE) from a Tunisian cultivar to prevent fat-induced disturbances. Data showed that a high-fat diet (HFD) provoked dyslipidemia into plasma which is linked to an oxidative stress, an accumulation of transition metals such as manganese, copper, and zinc and a depletion of iron. GSSE prevented dyslipidemia by modulating lipase activity, together with increased antioxidant capacity and depletion of transition metals as well as of free radicals such as O₂ ^? and OH. These data indicated that GSSE has important preventive effects on HFD-induced obesity and oxidative stress whose transduction seems to involve transition metals. GSSE should be used as a safe anti-obesity agent that could find potential applications in metabolic disorders involving transition metals dyshomeostasis.     

RyR1 Deficiency in Congenital Myopathies Disrupts Excitation–Contraction Coupling

In skeletal muscle, excitation–contraction (EC) coupling is the process whereby the voltage‐gated dihydropyridine receptor (DHPR) located on the transverse tubules activates calcium release from the sarcoplasmic reticulum by activating ryanodine receptor (RyR1) Ca²⁺ channels located on the terminal cisternae. This subcellular membrane specialization is necessary for proper intracellular signaling and any alterations in its architecture may lead to neuromuscular disorders. In this study, we present evidence that patients with recessive RYR1‐related congenital myopathies due to primary RyR1 deficiency also exhibit downregulation of the alfa 1 subunit of the DHPR and show disruption of the spatial organization of the EC coupling machinery. We created a cellular RyR1 knockdown model using immortalized human myoblasts transfected with RyR1 siRNA and confirm that knocking down RyR1 concomitantly downregulates not only the DHPR but also the expression of other proteins involved in EC coupling. Unexpectedly, this was paralleled by the upregulation of inositol‐1,4,5‐triphosphate receptors; functionally however, upregulation of the latter Ca²⁺ channels did not compensate for the lack of RyR1‐mediated Ca²⁺ release. These results indicate that in some patients, RyR1 deficiency concomitantly alters the expression pattern of several proteins involved in calcium homeostasis and that this may influence the manifestation of these diseases.     

Neuroprotective effects of IGF-I against TNFalpha-induced neuronal damage in HIV-associated dementia

Human immunodeficiency virus type 1 (HIV-1) infection often results in disorders of the central nervous system, including HIV-associated dementia (HAD). It is suspected that tumor necrosis factor-alpha (TNFalpha) released by activated and/or infected macrophages/microglia plays a role in the process of neuronal damage seen in AIDS patients. In light of earlier studies showing that the activation of the insulin-like growth factor I receptor (IGF-IR) exerts a strong neuroprotective effect, we investigated the ability of IGF-I to protect neuronal cells from HIV-infected macrophages. Our results demonstrate that the conditioned medium from HIV-1-infected macrophages, HIV/CM, causes loss of neuronal processes in differentiated PC12 and P19 neurons and that these neurodegenerative effects are associated with the presence of TNFalpha. Furthermore, we demonstrate that IGF-I rescues differentiated neurons from both HIV/CM and TNFalpha-induced damage and that IGF-I-mediated neuroprotection is strongly enhanced by overexpression of the wt IGF-IR cDNA and attenuated by the antisense IGF-IR cDNA. Finally, IGF-I-mediated antiapoptotic pathways are continuously functional in differentiated neurons exposed to HIV/CM and are likely supported by TNFalpha-mediated phosphorylation of I(kappa)B. All together these results suggest that the balance between TNFalpha and IGF-IR signaling pathways may control the extent of neuronal injury in this HIV-related experimental setting.     

Screening for coeliac disease among Egyptian children

Introduction

To screen for coeliac disease in Egyptian children with non-endocrinal short stature, refractory iron deficiency anaemia and type 1 diabetes. Also, to evaluate the sensitivity and specificity of different serological tests for diagnosis of coeliac disease (CD).

Material and methods

The study included 292 patients with clinical risk of CD. Testing for coeliac antibodies was performed, together with upper gastrointestinal endoscopy and small intestinal biopsy.

Results

Eleven patients (44%) among 25 patients with refractory iron deficiency anaemia, 23 patients (34.3%) among 67 patients with non-endocrinal short stature, and 6 patients (3%) among 200 patients with type I diabetes mellitus were diagnosed by jejunal biopsy as having coeliac disease. AGA (IgG) had the highest sensitivity for diagnosing CD (80.0%) followed by the TTG (72.7%) antibody, while ARA had the highest specificity (95.9%) followed by anti-EMA (94.7%).

Conclusions

Coeliac disease is more common in Egyptian children with refractory iron deficiency anaemia, non-endocrinal short stature and type 1 diabetes than was previously thought; therefore it is mandatory to screen such patients for CD. Serological tests showed fairly good sensitivity and specificity for the diagnosis; however, intestinal biopsy remains the cornerstone for definitive diagnosis of patients with immunological reaction to gluten.     

Myocardial performance index after surgical correction of ventricular septal defects

Introduction

The myocardial performance index (MPI) has been described as a non-invasive Doppler measurement of ventricular function. The aim of this study was to assess MPI following surgical correction of ventricular septal defect (VSD) and to evaluate its impact on postoperative recovery.

Material and methods

This is a prospective study involving 30 children (16 girls and 14 boys) operated on for VSD (group I). The control group (group II) consisted of 30 healthy children (age and sex matched).

Results

We found that both the right and left ventricular (RV and LV) MPI correlated significantly with the ejection fraction (EF) (r = –0.49, p = 0.006, r = –0.51, p = 0.004, respectively). The LV EF and the LV FS were negatively correlated, while the left and right ventricular MPI was positively correlated with the: LVEDD (p = 0.000), the VSD size (p = 0.000), and the postoperative course of the patients in terms of the duration of ventilation (p = 0.000), the duration of use of inotropics (p = 0.000) and the duration of staying in the ICU (p = 0.000). By linear regression, the factors that correlated with the postoperative course of VSD surgery were the RV MPI pre-surgery, MPI 2 days after surgery and the ejection fraction (p = 0.000).

Conclusions

Myocardial performance index is a useful index for measurement of the left and right ventricular function. It correlates significantly with the ejection fraction, fractional shortening, VSD size, and the left ventricular size. It also significantly predicts the outcome of VSD surgery.