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Corcionivoschi N.,National Childrens Research Center
Cell host & microbe | Year: 2012

Reactive oxygen species (ROS) play key roles in mucosal defense, yet how they are induced and the consequences for pathogens are unclear. We report that ROS generated by epithelial NADPH oxidases (Nox1/Duox2) during Campylobacter jejuni infection impair bacterial capsule formation and virulence by altering bacterial signal transduction. Upon C. jejuni invasion, ROS released from the intestinal mucosa inhibit the bacterial phosphotyrosine network that is regulated by the outer-membrane tyrosine kinase Cjtk (Cj1170/OMP50). ROS-mediated Cjtk inactivation results in an overall decrease in the phosphorylation of C. jejuni outer-membrane/periplasmic proteins, including UDP-GlcNAc/Glc 4-epimerase (Gne), an enzyme required for N-glycosylation and capsule formation. Cjtk positively regulates Gne by phosphorylating an active site tyrosine, while loss of Cjtk or ROS treatment inhibits Gne activity, causing altered polysaccharide synthesis. Thus, epithelial NADPH oxidases are an early antibacterial defense system in the intestinal mucosa that modifies virulence by disrupting bacterial signaling. Copyright © 2012 Elsevier Inc. All rights reserved.

Ozaki E.,Trinity College Dublin | Campbell M.,Trinity College Dublin | Doyle S.L.,Trinity College Dublin | Doyle S.L.,National Childrens Research Center
Journal of Inflammation Research | Year: 2015

The inflammasome is a molecular platform formed by activation of an innate immune pattern recognition receptor seed, such as NLRP3. Once activated, NLRP3 recruits the adapter ASC (apoptosis-related speck-like protein containing a caspase recruitment domain), which in turn recruits procaspase-1. Procaspase-1 autocatalyzes its cleavage and activation, resulting in maturation of the precursor forms of interleukin (IL)-1β and IL-18 into active proinflammatory cytokines and initiation of pyroptotic cell death. The NLRP3 inflammasome has been implicated in the pathogenesis of a wide variety of diseases, including genetically inherited autoinflammatory conditions as well as chronic diseases in which NLRP3 is abnormally activated. The NLRP3 inflammasome has been linked to diseases such as Alzheimer’s disease, atherosclerosis, metabolic syndrome, and age-related macular degeneration. In this review, we describe the NLRP3 inflammasome complex and its activation in disease, and detail the current therapies that modulate either the NLRP3 inflammasome complex itself or the two cytokines it is responsible for activating, ie, IL-1β and IL-18. © 2015 Ozaki et al.

Campbell M.,Trinity College Dublin | Doyle S.L.,Trinity College Dublin | Doyle S.L.,National Childrens Research Center
Journal of Molecular Medicine | Year: 2013

Age-related macular degeneration (AMD) is the leading cause of central vision loss worldwide. While activation of the immune system has been implicated in disease progression, the pathways involved remain relatively unclear. Typically, inflammatory responses are caused as a result of pathogenic infection. However, in chronic conditions, like AMD, a form of 'sterile' inflammation can exist in localised areas of the body in response to modified host-derived elements and particulate matter accumulation, due to the activation of a complex termed the 'inflammasome'. Inflammasomes control the activity of two major pro-inflammatory cytokines, namely, interleukin (IL)-1β and IL-18, by allowing for their cleavage from inactive pro-forms into mature cytokines. The major pathological hallmark common to both 'dry' and 'wet' AMD is the presence of extracellular deposits, known as drusen, below the retinal pigment epithelium in the macula of the eye. Past studies have shown that host-derived particulate matter such as amyloid deposits and atherosclerotic plaques can be 'sensed' by the NLRP3-inflammasome causing cleavage of pro-IL-1β and pro-IL-18. We have recently reported that the NLRP3-inflammasome can also 'sense' drusen isolated from human AMD donor eyes and that IL-18 protects against the development of choroidal neovascularisation in a model that mimics 'wet' AMD. In fact, since then, a number of studies have reported roles for the NLRP3-inflammasome in AMD. This review will focus on describing, comparing and contrasting these reports and analyzing the potential for manipulating the NLRP3-inflammasome as a therapy for AMD. © 2013 Springer-Verlag Berlin Heidelberg.

Puri P.,National Childrens Research Center
Journal of Pediatric Surgery | Year: 2010

Purpose: The pathogenesis of pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) is not fully understood. Platelet-derived growth factor A (PDGFA) and platelet-derived growth factor receptor α (PDGFRα) play a crucial role in lung development. It has been reported that PDGF induces H2O2-production and that oxidative stress may be an important mechanism for the impaired lung development in the nitrofen rat model. We hypothesized that pulmonary expression of PDGFA and PDGFRα is altered in the nitrofen induced CDH model. Materials and Methods: Pregnant rats received 100 mg nitrofen or vehicle on gestational day 9 (D9) and were sacrificed on D15, D18 or D21. RNA was extracted from fetal left lungs and mRNA levels of PDGFA and PDGFRα were determined using real-time polymerase chain reaction. Immunohistochemistry for protein expression of PDGFA and PDGFRα was performed. Pulmonary H2O2 was measured colorimetrically. Results: mRNA levels of PDGFRα at D15 (4.50 ± 0.87) and PDGFA at D18 (2.90 ± 1.38) were increased in the nitrofen group (P < .05). Immunohistochemistry revealed increased pulmonary expression of PDGFRα and PDGFA. H2O2 content was significantly higher in the nitrofen group. Conclusions: Increased expression of PDGFA and PDGFRα suggests that pulmonary hypoplasia in the nitrofen CDH model may be owing to PDGF-induced oxidative stress during lung development. © 2010 Elsevier Inc. All rights reserved.

McAleer M.A.,National Childrens Research Center | McAleer M.A.,Trinity College Dublin | Irvine A.D.,National Childrens Research Center | Irvine A.D.,Trinity College Dublin
Journal of Allergy and Clinical Immunology | Year: 2013

Filaggrin is a major structural protein in the stratum corneum of the epidermis. Mutations in the filaggrin gene are the most significant known genetic risk factor for the development of atopic dermatitis. Mutations in the human filaggrin gene (FLG) also confer risk for the associated allergic diseases of food allergy, asthma, and allergic rhinitis. These discoveries have highlighted the importance of skin barrier function in the pathogenesis of atopic diseases and have motivated a surge in research characterizing the filaggrin-deficient skin barrier and its consequences. In this review we discuss the mechanisms through which mutations in this protein contribute to the pathogenesis of atopic dermatitis and associated atopic conditions. We focus on recent human and murine discoveries characterizing the filaggrin-deficient epidermis with respect to biophysical, immunologic, and microbiome abnormalities. © 2013 American Academy of Allergy, Asthma & Immunology.

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