Browsing by Author "Kelly, Margaret Mary"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Investigating pulmonary vascular B cells
    (2019-04-26) Podstawka, John; Yipp, Bryan G.; Hirota, Simon Andrew; Kelly, Margaret Mary; Flannigan, Kyle L.
    The lung is a vital organ which is required for gas exchange. The anatomy of the lung itself, immune molecules, and leukocytes provide the host with protection from harmful debris and pathogenic stimuli. A component of pulmonary host defense is neutrophils which are found within the lung capillary network. Within the pulmonary capillaries, there is a population of neutrophils which remains adherent to the vascular endothelium for extended periods of time and exhibits marginated behaviour. While pulmonary vascular neutrophils are important in the acute immune response of the lung, they tend to exhibit an aged and pro-inflammatory phenotype. While inflammation within the lung is necessary for host defence and is a part of wound healing, cellular infiltration of the lung significantly compromises oxygen delivery and carbon dioxide removal. Therefore, pulmonary inflammation must be tightly controlled and regulated. We previously determined that pulmonary vascular B cells regulate neutrophils via CD18-mediated interactions, labelling them MHCII+AnnexinV+, and that in the absence of B cells, the lung will develop pathological fibrotic interstitial lung disease. In this body of work, we determined that pulmonary intravascular B cells can marginate which allows them to specialize in regulating lung neutrophils. These B cells exhibit a mature, naïve, conventional B2 cell phenotype, and engage in marginated behaviour which can be mediated by CD49e or via CXCR5/CXCL13. Blocking CD49e decreased the amount B cell-neutrophil interactions taking place within the lung capillaries, and providing exogenous CXCL13 or neutralizing endogenous CXCL13 would respectively increase and decrease the amount of interactions. Moreover, we demonstrated an intratracheal injection of CXCL13 increased the number of neutrophils which exhibited an MHCII+AnnexinV+ phenotype; indicating increased regulation via B cell interactions. Thus, we acquired novel insight into how lung intravascular B cells are engaging in prolonged interactions with lung neutrophils; interactions which were previously defined as regulatory and important for maintaining inflammatory homeostasis.
  • Thumbnail Image
    ItemOpen Access
    Modulation of TGFβ1-induced Fibroblast-to-Myofibroblast Transition in response to Prostaglandin E2 Production by Human Rhinovirus-Infected Airway Epithelial Cells
    (2020-05-08) Pham, Diana Minh; Leigh, Richard A.; Proud, David G.; Kelly, Margaret Mary; Giembycz, Mark A.
    One of the cardinal features of asthma is the presence of airway remodeling, the structural changes that contribute to exaggerated narrowing of the airway. Fibroblast-to-myofibroblast transition (FMT) is an airway remodeling phenomenon whereby fibroblasts develop phenotypic characteristics of myofibroblasts. This increase in myofibroblasts leads to the excessive deposition of extracellular matrix proteins, leading to the thickening of the airway walls. Transforming growth factor beta-1 (TGFβ1) is highly expressed in asthmatics and is known to upregulate fibroblast alpha-smooth muscle actin (α-SMA) expression, a characteristic marker of myofibroblasts. Given that human rhinovirus (HRV) infections are postulated to be involved in the pathogenesis of airway remodeling in asthma, we originally hypothesized that human airway epithelial cells promoted TGFβ1-induced FMT based on α-SMA expression by secreting mediator(s) upon HRV infection. Interestingly, our data consistently demonstrated that supernatants from HRV-infected epithelial cells inhibited TGFβ1-induced α-SMA in fibroblasts compared to supernatants from non-infected epithelial cells. This led us to hypothesize that HRV-infected airway epithelial cells released PGE2 which acts via EP1-4 receptors on fibroblasts to suppress TGFβ1-induced α-SMA expression. Using an in vitro cell culture model, we confirmed HRV-infection of epithelial cells result in the upregulation of PGE2 and validated that PGE2 inhibits TGFβ1-induced α-SMA protein in fibroblasts. Furthermore, supernatants from epithelial cells treated with diclofenac, a non-selective cyclooxygenase inhibitor, prior to HRV infection had reduced ability to inhibit TGFβ1-induced α-SMA expression in fibroblasts. Finally, we demonstrated that PGE2 acts on the fibroblast EP2 receptor to downregulate TGFβ1-induced FMT. In conclusion, our research findings may account for why healthy, non-asthmatic individuals are prevented from developing TGFβ1-induced FMT following repeated rhinovirus infections. This thesis instigates future investigation on whether well-characterized asthmatic cells behave differently to render it vulnerable to TGFβ1-induced FMT following rhinovirus infections.