Research

Leukocyte Trafficking Group research

Mechanisms of Leukocyte Recruitment

The hypotheses which drive the work in our laboratory are that leukocyte recruitment is of central importance in inflammatory diseases, and the mechanisms whereby leukocytes enter sites of inflammation are highly complex and variable depending on the disease process and tissue involved. As a result of this research, we hope to develop an understanding of how leukocytes contribute to a range of inflammatory diseases. This understanding forms a vital step in the development of the next generation of novel anti-inflammatory therapeutics.

To achieve this aim, the major technique used by our laboratory is in vivo imaging, including multi-photon and spinning disk confocal intravital microscopy, for the investigation of leukocyte function in intact tissues. This allows us to gain an unrivalled understanding of leukocyte function and behaviour as it occurs in an inflammatory response.

In this work, we focus on the contributions of key inflammatory molecules, such as adhesion molecules and other cell surface molecules, cytokines, chemokines and signaling molecules, and the tissue- and context-specific roles of these molecules.

Leukocyte recruitment

Neutrophils (magenta) undergoing interactions with the endothelial lining of a postcapillary venule of a muscle (muscle cells visible via red striations, capillaries labeled in green).

Immune cell interactions in the inflamed Glomerulus

The renal glomerulus is a specialized capillary bed which serves the function of blood filtration for the generation of urine. However, the glomerulus is also the target of damaging immune responses in the diseases of glomerulonephritis and systemic lupus erythematosus (SLE). In these conditions, leukocytes accumulate within glomeruli, where they play critical roles in glomerular injury and dysfunction.

We use multiphoton and spinning disk confocal intravital microscopy to examine the mechanisms of leukocyte recruitment to this specialized vasculature in vivo. Our multiphoton microscopy studies have shown that the process of leukocyte recruitment in glomeruli is distinct from that in most vascular beds. As part of these studies we have demonstrated that leukocytes can mediate glomerular injury while retained within the blood vessels of the glomerulus, and that the duration of their retention in these vessels is a key factor in facilitating injury (Devi et al., Nature Medicine 2013).

In more recent work we have been investigating the roles of interactions between various immune cell subsets within the glomerular microvasculature (Finsterbusch et al., Proc. Natl Acad. Sci. USA 2016), including neutrophils, monocytes and CD4+ T cells, in the development of inflammatory glomerular disease.

Inflamed glomerulus

Neutrophils (red) within the capillaries of a glomerulus (unstained). One of the neutrophils is interacting with a patrolling monocyte (green) (see Finsterbusch et al., Proc Natl Acad Sci USA 2016).

Leukocyte-platelet interactions in the inflamed vasculature

Platelets are well known for their essential roles in controlling bleeding and thrombosis. However, platelets also make important contributions in inflammation, particularly by promoting the actions of inflammatory leukocytes such as neutrophils. We are using spinning disk confocal microscopy to investigate how interactions between platelets and neutrophils control the proinflammatory actions of neutrophils in acute glomerular inflammation.

Inflamed vasculature 

Neutrophils (green) and platelets (red) undergoing retention within the capillaries of a glomerulus (blue).

Regulatory T cell recruitment and function in inflammatory skin disease

In forms of skin disease such as atopic dermatitis and allergic contact dermatitis, T lymphocytes are recruited to the skin where they play key roles in excessive and debilitating inflammatory responses. Different types of T cells (CD8+, CD4+, regulatory T cell) can play different roles in this response. We are using the contact sensitivity model of T cell-mediated skin inflammation to investigate the mechanisms of T cell recruitment to the inflamed skin, with a particular focus on the anti-inflammatory CD4+ regulatory T cell subset. We have developed novel imaging approaches to detect this rare subset in skin blood vessels (Abeynaike et al., J. Immunol 2014) and in the dermis (Chow et al., J. Immunol 2013), allowing the investigation of novel mechanisms of action of this important immune cell.

Skin disease 

Immune cells (pink) recruited to the skin as part of a contact hypersensitivity response.

Roles of tetraspanin family members in leukocyte migration

Tetraspanins are cell surface molecules expressed on a wide range of cells. However, their functions in the immune system are only beginning to be unraveled. In collaboration with A/Prof. Mark Wright (Department of Immunology & Pathology), we are investigating the actions of tetraspanin family members CD37, CD81 and CD53 in controlling immune cell function. As tetraspanins have been shown to regulate migration of other cell types, these investigations are focusing on how these molecules control the migration of different immune cell subsets around the body in health and disease (Wee et al., J. Immunol. 2015).

Leukocyte migration

Neutrophils (green) in which the adhesion molecule LFA-1 (red) has undergone internalization (see Wee et al., J. Immunol 2015).