ORCID Profile
0000-0003-4553-018X
Current Organisation
University of Dublin Trinity College
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Publisher: Springer Science and Business Media LLC
Date: 24-07-2005
DOI: 10.1038/NM1282
Abstract: The latent transcription factor Stat3 is activated by gp130, the common receptor for the interleukin (IL)-6 cytokine family and other growth factor and cytokine receptors. Ligand-induced dimerization of gp130 leads to activation of the Stat1, Stat3 and Shp2-Ras-Erk signaling pathways. Here we assess genetically the contribution of exaggerated Stat3 activation to the phenotype of gp130 (Y757F/Y757F) mice, in which a knock-in mutation disrupts the negative feedback mechanism on gp130-dependent Stat signaling. Compared to gp130 (Y757F/Y757F) mice, reduced Stat3 activation in gp130 (Y757F/Y757F) Stat3(+/-) mice increased their lifespan, prevented splenomegaly, normalized exaggerated hepatic acute-phase response and lymphocyte trafficking, and suppressed the growth of spontaneously arising gastric adenomas in young mice. These lesions share histological features of gastric polyps in aging mice with monoallelic null mutations in Smad4, which encodes the common transducer for transforming growth factor (TGF)-beta signaling. Indeed, hyperactivation of Stat3 desensitizes gp130 (Y757F/Y757F) cells to the cytostatic effect of TGF-beta through transcriptional induction of inhibitory Smad7, thereby providing a novel link for cross-talk between Stat and Smad signaling in gastric homeostasis.
Publisher: Elsevier BV
Date: 2014
Publisher: The American Association of Immunologists
Date: 18-01-2010
Abstract: IL-6 responses are classically orchestrated via a membrane-bound IL-6R (CD126) α subunit (classical IL-6R signaling) or through a soluble form of this cognate receptor (IL-6 trans signaling). Appraisal of IL-6R expression on human and mouse T cells emphasized that IL-6R expression is closely linked with that of CCR7 and CD62L. In this regard, infiltrating effector T cells from clinical and experimental peritonitis episodes lose IL-6R expression, and anti-CD3/CD28 Ab costimulation of peripheral T cells in vitro leads to a downregulation in IL-6R expression. Consequently, IL-6 signaling through membrane-bound IL-6R seems to be limited to naive or central memory T cell populations. Loss of IL-6R expression by activated T cells further suggests that these effector cells might still retain IL-6 responsiveness via IL-6 trans signaling. Using IL-6R–deficient mice and recombinant tools that modulate the capacity of IL-6 to signal via its soluble receptor, we report that local control of IL-6 trans signaling regulates the effector characteristics of the T cell infiltrate and promotes the maintenance of IL-17A–secreting CD4+ T cells. Therefore, we concluded that classical IL-6R signaling in naive or central memory CD4+ T cells is required to steer their effector characteristics, whereas local regulation of soluble IL-6R activity might serve to maintain the cytokine profile of the Th cell infiltrate. Therefore, the activation status of a T cell population is linked with an alteration in IL-6 responsiveness.
Publisher: American Society for Microbiology
Date: 09-2015
DOI: 10.1128/IAI.00358-15
Abstract: The capacity for intracellular survival within phagocytes is likely a critical factor facilitating the dissemination of Staphylococcus aureus in the host. To date, the majority of work on S. aureus -phagocyte interactions has focused on neutrophils and, to a lesser extent, macrophages, yet we understand little about the role played by dendritic cells (DCs) in the direct killing of this bacterium. Using bone marrow-derived DCs (BMDCs), we demonstrate for the first time that DCs can effectively kill S. aureus but that certain strains of S. aureus have the capacity to evade DC (and macrophage) killing by manipulation of autophagic pathways. Strains with high levels of Agr activity were capable of causing autophagosome accumulation, were not killed by BMDCs, and subsequently escaped from the phagocyte, exerting significant cytotoxic effects. Conversely, strains that exhibited low levels of Agr activity failed to accumulate autophagosomes and were killed by BMDCs. Inhibition of the autophagic pathway by treatment with 3-methyladenine restored the bactericidal effects of BMDCs. Using an in vivo model of systemic infection, we demonstrated that the ability of S. aureus strains to evade phagocytic cell killing and to survive temporarily within phagocytes correlated with persistence in the periphery and that this effect is critically Agr dependent. Taken together, our data suggest that strains of S. aureus exhibiting high levels of Agr activity are capable of blocking autophagic flux, leading to the accumulation of autophagosomes. Within these autophagosomes, the bacteria are protected from phagocytic killing, thus providing an intracellular survival niche within professional phagocytes, which ultimately facilitates dissemination.
Publisher: Elsevier BV
Date: 04-2022
Publisher: Proceedings of the National Academy of Sciences
Date: 23-06-2005
Abstract: Interleukin (IL)-6 signaling through its soluble receptor (IL-6 transsignaling) directs transition between innate and acquired immune responses by orchestrating the chemokine-directed attraction and apoptotic clearance of leukocytes. Through analysis of mononuclear cell infiltration in WT and IL-6-deficient mice during peritoneal inflammation, we now report that IL-6 selectively governs T cell infiltration by regulating chemokine secretion (CXCL10, CCL4, CCL5, CCL11, and CCL17) and chemokine receptor (CCR3, CCR4, CCR5, and CXCR3) expression on the CD3 + infiltrate. Although blockade of IL-6 trans-signaling prevented chemokine release, chemokine receptor expression remained unaltered suggesting that this response is regulated by IL-6 itself. To dissect the signaling events promoting T cell migration, inflammation was established in knock-in mice expressing mutated forms of the universal signal-transducing element for IL-6-related cytokines gp130. In mice ( gp130 Y757F/Y757F ) deficient in SHP2 and SOCS3 binding, but presenting hyperactivation of STAT1/3, T cell recruitment and CCL5 expression was enhanced. Conversely, both of these parameters were suppressed in mice with ablated gp130-mediated STAT1/3 activation ( gp130 ΔSTAT/ΔSTAT ). T cell migration was related to STAT3 activity, because monoallelic deletion of Stat3 in gp130 Y757F/Y757F mice ( gp130 Y757F/Y757F : Stat3 +/- ) corrected the exaggerated responses observed in gp130 Y757F/Y757F mice. Consequently, STAT3 plays a defining role in IL-6-mediated T cell migration.
Publisher: Public Library of Science (PLoS)
Date: 27-12-2012
Publisher: Cold Spring Harbor Laboratory
Date: 03-09-2021
DOI: 10.1101/2021.09.01.21262953
Abstract: SARS-CoV-2 infection causes a wide spectrum of disease severity. Immune changes associated with severe disease include pro-inflammatory cytokine production and expansion of immature myeloid populations. The relative importance of the immunological changes in driving progression to severe disease remain poorly understood. We aimed to identify and rank clinical and immunological features associated with progression to severe COVID-19. We sought to use tests available in an on-site diagnostic hospital laboratory to identify an immunological signature for severe disease development which could be detected prior to peak severity thereby allowing initiation of therapeutic interventions. We used univariate and multivariate analysis, including unbiased machine learning, to investigate the relationships between clinical and demographic characteristics, inflammatory markers, and leukocyte immunophenotypes with progression to severe disease in 108 patients and to rank these in importance. A combination of four features (elevated levels of interleukin-6 and C-reactive protein, coupled with reduced monocyte HLA-DR expression and reduced neutrophil CD10 expression), were strongly predictive of severe disease with an average prediction score of 0.925. Severe COVID-19 can be predicted by a combination of emergency myelopoiesis (CD10-neutrophils and HLA DR-monocytes) and inflammation (raised IL-6 and CRP) These changes can be identified from tests carried out prior to peak illness severity in a diagnostic laboratory This predictive model was derived from a cohort of patients with a wide range of ages, frailty and COVID-19 severity
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Rachel McLoughlin.