Division of Respirology

Luke J Janssen

M.Sc., Ph.D.

Professor, Division of Respirology, Department of Medicine

St. Joseph's Healthcare

Firestone Institute of Respiratory Health

 

 

 

Education and Professional Standing Awards and Distinctions

  • B. Sc., McMaster University (Biochemistry), 1984
  • M.Sc., McMaster University (Medical Sciences), 1987
  • Ph.D., McMaster University (Medical Sciences), 1990
  • Postdoctoral research fellowship, University of Western Ontario, 1990-1993
  • Assistant Professor, Department of Medicine, McMaster, 1993-1998
  • Member, Firestone Institute for Respiratory Health, 1999-present
  • Associate Professor, Department of Medicine, McMaster, 1999-2005
  • Professor, Department of Medicine, McMaster, 2005-present

Research Interests

Dr. Janssen’s major research area is focused on calcium handling in a variety of cell types (airway smooth muscle; fibroblasts; eosinophils; lymphocytes). This includes three major themes:

(i) the mechanisms by which the cytosolic concentrations of calcium are regulated up and down within those cells. Addresses the various ion channels, pumps and exchangers which co-ordinate to regulate membrane potential, the movement of Ca2+ within the cell, its organelles and across the plasmalemma. Experimental techniques include patch-clamp electrophysiology, confocal fluorimetry.

(ii) how those changes in [Ca2+] are interpreted by the cells. [Ca2+]-responses include both the sustained changes which are measured on time-scales of minutes to days, as well as much more brief transient changes; the latter often manifest as periodic or rhythmic changes (calcium-oscillations or calcium-waves). These various responses are "interpreted" differently by effectors such as ion channels and enzymes, leading to selective changes in one kind of cell function over another (gene expression; cytoskeletal rearrangement; contraction/relaxation). Experimental techniques also include patch-clamp electrophysiology and confocal fluorimetry, as well as use of force transducers to measure tension, pressure transducers and videomicrometry to measure changes in diameter, pressure and flow in cannulated/pressurized vessels, videomicrometry of lung slices, cell migrational assays, enzyme assays, RT-PCR, Western blots, etc.

(iii) how the cellular physiological events referred to above are altered in various disease states. The latter particularly include asthma and pulmonary fibrosis, but our work also touches on hypertension, COPD, inflammation and immunity. The ultimate goal is to identify potential novel therapeutic strategies.

We have published over 130 peer-reviewed papers in journals such as Journal of Clinical Investigation, American Journal of Physiology, American Journal of Respiratory and Critical Care Medicine, European Respiratory Journal and many others. We have been funded by CIHR, NSERC, Heart&Stroke, OTS and different Pharma companies over the years. Dr. Janssen has competed successfully for career awards from: the Medical Research Council of Canada / CIHR; Pharmaceutical Manufacturer's Association of Canada; Canadian Lung Association; JP Bickell Foundation; and the Province of Ontario (Premier's Research Excellence Award).

Recent Publications (selected to convey breadth of research activities and range of experimental techniques)

  1. Mukherjee, S.M., E. Ayaub, J. Murphy, M. Kolb, K. Ask, L. J. Janssen. Nifedipine attenuates bleomycin-induced fibrosis by blocking calcium oscillations.  American Journal of Respiratory Cell and Molecular Biology.
  2. Mukherjee, S.M., M. Kolb, L. J Janssen.  Platelet derived growth factor (PDGF) evoked Ca2+ wave and enhanced gene expression through IP3 gated channel in cultured human pulmonary fibroblast. Int J Biochem Cell Biol. 45(7):1516-24, 2013
  3. J. Hernandez, L. J. Janssen. Involvement of L-type Ca2+ channels, Ca2+-induced Ca2+ release, and BKCa channels in airway stretch-induced contraction. European Journal of Pharmacology 696(1-3):161-5, 2012
  4. M. Rahman, L. J. Janssen. NCX in airway smooth muscle and altered expression in allergen-induced hyperresponsiveness. Acta Physiologica 205(2):279-291, 2012
  5. T. Tazzeo, G. Bates, H. N. Roman, A-M Lauzon, M. D. Khasnis, M. Eto and L. J. Janssen. Caffeine relaxes airway smooth muscle through actin depolymerization. American Journal of Physiology 303(4):L334-42
  6. P. Dyrda, Tazzeo T, DoHarris L, Nilius B, Roman HN, Lauzon AM, Aziz T, Lukic D, L. J. Janssen. Acute response of airway muscle to extreme temperature includes disruption of actin-myosin interaction. American Journal of Respiratory Cell and Molecular Biology 44(2):213-21, 2011
  7. Khan, M. A., R. Ellis, M. D. Inman, J. H. T. Bates, M. J. Sanderson, L. J. Janssen. The influence of airway wall stiffness and parenchymal tethering on the dynamics of bronchoconstriction. American Journal of Physiology 299(1):L98-L108, 2010