Airway Smooth Muscle Cells Are Insensitive to the Anti-Proliferative

Immunobiology 224 (2019) 490–496 Contents lists available at ScienceDirect Immunobiology journal homepage: www.elsevier.com/locate/imbio Airway smooth muscle cells are insensitive to the anti-proliferative effects of corticosteroids: The novel role of insulin growth factor binding Protein-1 in T asthma ⁎ Hong Buia, Yassine Amranib, Brian Deeneyc, Reynold A. Panettieric, Omar Tlibad, a Penn Health System, Microbiology laboratories, University of Pennsylvania, Philadelphia, PA, USA b Institute for Lung Health, Department of Infection, Inflammation and Immunity, University of Leicester, United Kingdom c Rutgers Institute of Translational Medicine and Sciences, Rutgers School of Medicine, New Brunswick, NJ, USA d Department of Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY, USA ARTICLE INFO ABSTRACT Keywords: Airway remodeling in asthma manifests, in part, as enhanced airway smooth muscle (ASM) mass, due to myocyte Asthma proliferation. While the anti-proliferative effects of glucocorticoid (GC) were investigated in normal ASM cells Glucocorticoid insensitivity (NASMC), little is known about such effects in ASM cells derived from asthma subjects (AASMC). We posit that Airway smooth muscle GC differentially modulates mitogen-induced proliferation of AASMC and NASMC. Cells were cultured, starved, Proliferation then treated with Epidermal growth factor (EGF) (10 ng/ml) and Platelet-derived growth factor (PDGF) (10 ng/ Growth ml) for 24 h and/or fluticasone propionate (FP) (100 nM) added 2 h before. Cell counts and flow cytometry Airway remodeling analyses showed that FP failed to decrease the cell number of and DNA synthesis in AASMC irrespective of mitogens used. We also examine the ability of Insulin Growth Factor Binding Protein-1 (IGFBP-1), a steroid- inducible gene that deters cell growth in other cell types, to inhibit proliferation of AASMC where FP failed. We found that FP increased IGFBP1 mRNA and protein levels. Interestingly, the addition of IGFBP1 (1 μg/ml) to FP completely inhibited the proliferation of AASMC irrespective to the mitogens used. Further investigation of different signaling molecules involved in ASM growth and GC receptor functions (Protein kinase B (PKB/AKT), Mitogen-activated protein kinases (MAPKs), Focal Adhesion Kinase (FAK)) showed that IGFBP-1 selectively decreased mitogen-induced p38 phosphorylation in AASMC. Collectively, our results show the insensitivity of AASMC to the anti-proliferative effects of GC, and demonstrate the ability of IGFBP1 to modulate AASMC growth representing, hence, a promising strategy to control ASM growth in subjects with GC insensitive asthma. 1. Introduction increased ASM mass in bronchial biopsies obtained from patients with asthma (Bentley et al., 2009; Bentley and Hershenson, 2008) supports Asthma is a chronic airway inflammatory disease characterized by the notion that ASM is a critical player in the pathogenesis of asthma shortness of breath, chest tightness, coughing, and wheezing (Wahidi and Kraft, 2012; Panettieri, 2015). Mitogens such as Platelet- (Panettieri, 2016). While inhaled glucocorticoids (GC) are the most Derived Growth Factor (PDGF) and Epidermal Growth Factor (EGF) commonly used treatment in asthma, some patients with severe asthma modulate ASM growth (Stamatiou et al., 2012; Vlahos et al., 2003). The are insensitive to GC therapy (Marwick et al., 2010). Consequently, molecular mechanisms modulating ASM cell proliferation involve nu- such patients contribute disproportionately to the health care costs and merous signaling pathways. For example, to promote cell growth, PDGF morbidity associated with asthma (Moore and Peters, 2006). Hence, and EGF bind to receptors with intrinsic tyrosine kinase activity (RTK) significant research efforts aiming at defining the mechanism(s) un- (reviewed in (Tliba and Panettieri, 2009)) and promote the activation derlying GC insensitivity, more importantly, strategies that reestablish of serine-threonine kinases AKT and mitogen-activated protein kinases GC responsiveness are needed. (MAPKs). Ultimately, via the phosphorylation of other intermediate Studies showed that patients with severe asthma benefited from molecules, the upregulation of cyclin D1 facilitates ASM cells transition bronchial thermoplasty, a therapy that attenuates bronchoconstriction through the cell cycle (Tliba and Panettieri, 2009). Interestingly, the by reducing airway smooth muscle (ASM) mass; this finding and that of ability of some mitogens to promote growth of normal ASM cells is ⁎ Corresponding author at: Department of Biomedical Sciences, College of Veterinary Medicine, Long Island University, Brookville, NY, USA. E-mail address: [email protected] (O. Tliba). https://doi.org/10.1016/j.imbio.2019.05.006 Received 29 March 2019; Received in revised form 20 May 2019; Accepted 21 May 2019 Available online 23 May 2019 0171-2985/ © 2019 Elsevier GmbH. All rights reserved. H. Bui, et al. Immunobiology 224 (2019) 490–496 sensitive to the anti-proliferative effects of GC, although differentially proliferative effects of FP. After that, cells were trypsinized, pelleted by with thrombin being more sensitive to GC than EGF (Vlahos et al., centrifugation, and suspended in a 15 ml conical tubes. Next, 10 μlof 2003; Stewart et al., 1995; Dekkers et al., 2012). Yet, little is known suspended cells were mixed with 10 μl of Trypan Blue stain (Life about the anti-proliferative effects of GC on ASM cells derived from Technologies, Frederick, MD) and loaded onto chamber slides. The asthma subjects. Countess II automated cell counter (Life Technologies) was used to GC acts through different molecular mechanisms of action. The two perform cell count of viable cells. Of note, IGFBP-1 used at 1 μg/ml did most well-described are transrepression and transactivation (van der not affect the viability of ASM cell viability as assessed by the MTT Velden, 1998). When GC binds to its receptor in the cytoplasm, the GC assay (data not shown). receptor (GR) is released from heat shock protein (HSP)-90 complex to translocate to the nuclear compartment of the cell. Transrepression 2.3. Bromodeoxyuridine (BrdU) incorporation occurs when the GR binds to the cis-element of inflammatory transcription factors such as activating protein-1 (AP-1) and nuclear factor ASM cells were treated as above. To measure DNA synthesis, BrdU κB (NF-κB) to inhibit the expression of pro-inflammatory genes. (GE Healthcare, Mickleton, NJ) was added to culture media for 18 h Transactivation occurs when the GR binds to the GC response element before cells were trypsinized and pelleted by centrifugation. To de- (GRE) on the promoter of GC inducible genes, such as MAPK phos- nature DNA, cells were exposed to 2 N Hydrochloric Acid (HCl) for phatase 1 (MKP-1) (Quante et al., 2008), glucocorticoid-induced leu- 30 min in 37 °C water bath. Next, cells were neutralized with 0.1 M cine zipper (GILZ) (Eddleston et al., 2007), and insulin-like growth Sodium Tetraborate and washed with Immunofluorescence Antibody factor binding protein-1 (IGFBP-1) (Lee et al., 1997; Suh and Rechler, Assay (IFA) buffer supplemented with HEPES Saline, Fetal Bovine 1997; Suh et al., 1995, 1996) to induce their transcription. Importantly, Serum (FBS) (Hyclone Laboratories, Logan, Utah), and Sodium Azide while the role of MKP-1 and GILZ in mediating GC effects has been (Sigma-Aldrich, St. Louis, MO). After that, cells were incubated with extensively investigated, the role of IGFBP-1 in mediating GC effects anti-BrdU fluorescence conjugated secondary antibody (BD Biosciences, has been poorly investigated. San Jose, CA). Tween 20/IFA buffer at 0.5% was then used to wash the IGFBP1 has IGF1-dependent and -independent activities. IGF1-de- cells before they were pelleted by centrifugation and re-suspended in pendent activity of IGFBP1 involves its binding to IGF1 and subse- solution of Propidium Iodide and RNase (Sigma) for Flow Cytometric quently modulates IGF1 cellular actions (Kajimura et al., 2005). IGF1- analysis on FACScalibur (BD Biosciences). independent activities involve IGFBP-1′s RGD (Arg-Gly-Asp) motif present in the C-terminal domain. RGD is a ligand of integrin α5β1 that 2.4. Immunoblot analysis acts independently of IGF receptors (Jones et al., 1993). Several studies investigated the role of IGFBP1 in modulating cell growth. For instance, Growth-arrested ASM cells were exposed to FP (100 nM), then total IGFBP-1 decreases the growth of breast cancer cells in response to es- proteins were extracted. Immunoblot analyses were conducted as we trogen and serum (Van den Berg et al., 1997) and the thymidine uptake reported previously (Bouazza et al., 2014, 2012) using IGFBP-1 anti- in rat aortic smooth muscle cells (Motani et al., 1995). Evidence sug- body (Santa Cruz Biotechnology, Santa Cruz, CA). For normalization gests that IGFBP-1 downregulates the expression of key proteins asso- purposes, an anti-glyceraldehyde 3-phosphate dehydrogenase (GAPDH) ciated with cell growth such as ERK and AKT in fibroblasts (Prokop antibody (Santa Cruz Biotechnology) was used to stain the corre- et al., 2013). However, the expression and the role of IGFBP-1 in sponding stripped nitrocellulose membrane. modulating ASM cell responses remains unknown. In parallel experiments, growth-arrested AASMC were treated with Because increased ASM mass in asthma is a critical component of PDGF 10 ng/ml for 24 h in and/or FP (100 nM) and/or of IGFBP-1 asthma pathogenesis, therapeutic strategies aiming at reducing ASM (1 μg/ml) added 2 and 3

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