Theme 4: Control of leukocyte recruitment and microvascular permeability during inflammation

Supervisors: A/Prof  Michael Hickey
Telephone: 9594 5519
Email: Michael.Hickey@med.monash.edu.au

1. Mechanisms of T cell recruitment and migration in Contact Sensitivity

   (A/Prof. Michael Hickey & Dr. James Deane)

   Diseases such as psoriasis, allergic contact dermatitis and atopic dermatitis are inflammatory conditions caused by recruitment of T cells of the skin.  T cells exist in many subsets, including CD4+ Th1, Th2, & Th17, CD8+, and T regulatory cells.  Emerging evidence indicates distinctly different functional roles for the various T cell subsets in inflammatory skin disease.  In addition, the mechanisms whereby they gain entry into the skin may involve different adhesion molecules and chemokines for each subset.

   The focus of our laboratory is the use of in vivo imaging to investigate the molecular mechanisms whereby leukocytes interact with the vascular endothelium, and migrate into sites of inflammation.  This project will utilise state of the art imaging approaches (e.g. multi-photon confocal microscopy, and spinning disk confocal microscopy) to examine T cell-endothelial cell interactions in the vasculature of the skin, and also investigate the mechanisms of T cell migration within the inflamed interstitium.  The mechanisms of adhesion and migration of CD4+, CD8+ and T regulatory cells will be examined.

2. Macrophage Migration Inhibitory Factor (MIF) and human endothelial cell function

   (A/Prof. Michael Hickey & Prof. Eric Morand)

   The ability of endothelial cells to express adhesion molecules and chemokines underlies their role in the key feature of inflammatory responses, leukocyte recruitment.  These molecules serve specific functions in enabling leukocytes traveling rapidly in the mainstream of blood flow to tether and roll and subsequently arrest on the endothelial surface, events which are required for leukocytes to enter inflammatory sites.

   Recently we have use siRNA to inhibit expression of the proinflammatory mediator, macrophage migration inhibitory factor (MIF), in human endothelial cells in vitro.   These experiments have demonstrated that MIF promotes endothelial adhesive function by amplifying expression of adhesion molecules and chemokines.  This leads to an increased ability to induce rolling and adhesion of human leukocytes under flow conditions.

   The aim of this project will be to examine this issue further, by determining whether MIF also regulates the subsequent step of leukocyte transmigration across the endothelial monolayer.  These experiments will also investigate the intracellular signaling molecules whereby MIF promotes expression of adhesion molecules and chemokines.  These experiments will utilise in vitro approaches to culture human endothelial cells, alter expression levels of inflammatory mediators and signaling molecules in these cells, and in vitro flow chamber assays to assess interactions between human endothelial cells and leukocytes under flow conditions.

3. Mechanisms of T cell recruitment in a novel model of T cell-mediated glomerular injury

   (A/Prof. Michael Hickey & A/Prof. Richard Kitching)

   Glomerulonephritis is an inflammatory disease of the kidney, the most important forms of which are mediated by the recruitment of inflammatory leukocytes to the glomerulus.  Emerging evidence implicates CD4+ T cells as being key initiating leukocytes in this disease.  However, the process whereby these T cells are recruited to the glomerulus and recognise their cognate antigen to promulgate the inflammatory process remains undefined.

   We have developed a range of novel tools, including techniques for imaging the glomerular microvasculature in living mice, to enable the analysis of leukocyte function in the glomerulus.  The aim of this project will be to investigate the mechanisms of antigen-specific T cell recruitment to the glomerulus.  This project will utilise a range of techniques, including intravital microscopy of the kidney, in vitro T cell polarization, intracellular cytokine staining and immunohistochemistry for analysis of renal inflammation.

4. Tetraspanins as regulators of leukocyte migratory function

   (A/Prof. Michael Hickey & A/Prof. Mark Wright)

   Tetraspanins are a family of novel transmembrane proteins whose functions have not been fully elucidated.  Recent data have suggested that the tetraspanin CD37 is important in promoting leukocyte transmigration across the endothelium, and migration within the interstitium, suggesting that it might play key roles in inflammatory and immune responses.  The aim of this project will be to investigate this issue in vivo by examining leukocyte-endothelial cell interactions and migration in the inflamed microvasculature of wild-type and CD37-deficient mice.  This project, which is a collaboration between the laboratories of A/Prof. Michael Hickey (Centre for Inflammatory Diseases) and A/Prof. Mark Wright (Dept. of Immunology), will utilise a wide range of techniques, including in vivo imaging (multi-photon confocal microscopy, and spinning disk confocal microscopy) in living mice, as well as complementary in vitro approaches to determine the role of CD37 in leukocyte migration.