Welcome! You have reached the homepage for the laboratory of Dr. Bryan Heit. Our lab is part of the Department of Microbiology and Immunology at Western University, and we are members of the Center for Human Immunology, the lead centre for the CIHR Human Immunology Network.
Our interests surround the function of phagocytes – white blood cells which ingest (phagocytose) pathogens, particles, and dead cells. We focus on the cellular and molecular processes which control the function of these cells during the maintenance of homeostasis, infection and chronic inflammatory disease. Central to most of our studies is the study of efferoctyosis – the phagocytic removal of apoptotic (dying) cells, and how failures in this process lead to inflammation, autoimmunity and infection.
Phagocytes are a class of white blood cells which have the capacity to engulf large particles such as bacterial and fungal pathogens, and subsequently destroy the engulfed material. The term phagocyte literally translates to “cell that eats”, which is an apt description of the primary function of these cells in our bodies. While there are many types of phagocytes, the Heit lab focuses primarily on macrophages, which play key roles in both maintaining our bodies and in fighting infections.
We use a combination of advanced microscopy techniques, gene expression analysis and functional assays to investigate the activity of macrophages. Some examples of the methods we employ can be found on our YouTube channel.
One of the best parts of science is bringing new techniques and technologies into your lab. Our newest technique is SRRF imaging, which can more than double the resolution of nearly any widefield microscope, and can even be employed on living samples. The improvement this technology adds can be seen in the images of bovine aortic epithelial cells on the left, which have been stained for actin (yellow), DNA (cyan) and mitochondria (magenta).
SRRF imaging uses a specialised deconvolution approach which relies on the mapping of radial symmetry to resolve the positions of fluorophores with high precision. This process is repeated over a number of frames (10-100), with the convergence of signals between images used to refine fluorophore positions and non-convergence used to remove noise. The result is a dramatic improvement in both resolution and signal-to-noise ratios.
This amazing advance in microscopy was made possible by the work and free NanoJ plug-in for ImageJ/FIJI produced by Ricardo Henriques’s group at University College, UK. SRRF imaging will soon be available to approved users via our widefield core.
Additional papers and resources on SRRF Imaging:
The Heit lab is excited to announce the publication of our latest paper – a video methods paper describing our procedure for performing highly quantitative and precise measurements of efferocytosis. This is also our first publication with our new collaborator, Dr. Dan Wootton from the University of Liverpool.
Taruc, K., Yin, C., Wootton, D. G., Heit, B. Quantification of Efferocytosis by Single-cell Fluorescence Microscopy. J. Vis. Exp. (138), e58149, doi:10.3791/58149 (2018).
— Bryan Heit (@BryanHeit) August 20, 2018
The Heit Lab is excited to announce that we recently received the Breathe New Life Award, an operating grant which we will use to launch a new research initiative into the mechanisms used by macrophages to promote the healing of lungs following pneumonia, and how bacterial infections modulate this healing process. The ultimate goal is to understand why some patient recover normal lung function following bacterial pneumonia, while others will suffer lifelong impairment of their lung function. By investigating these processes we believe that it will become possible to identify those patients who are at risk of developing impaired lung function, and to develop treatments which will prevent the loss of lung function in these patients.
Pneumonia – infection of the lungs by pathogens such as bacteria – are a major cause of hospitalization and death among Canadians. Many pneumonia survivors experience a severe and lasting loss of lung function; the consequences of this range from long-term disability to death. In fact, the likelihood of a pneumonia patient dying from a post-pneumonia complication is higher than the likelihood of a patient dying from the complications of a heart attack or stroke. Clearly, better treatments for recovering lung function are required for pneumonia patients, both to restore normal lung function after disease, and to prevent the deaths resulting from post-pneumonia complications. This proposal is directly focused on understanding how and why lung function is lost following pneumonia. This work may lead to treatments which restore lung repair in pneumonia patients, thereby preventing the loss of lung function that is an all too common result of pneumonia. This would directly improve the lung health of the approximately 11,000 Canadians who die of the lost lung function following pneumonia each year.
This award would not be possible without the donations and volunteers that support the Lung Association, and would not have been possible without the scientific support of the Ontario Thoracic Society. For more information on the Lung Association, or to fund additional research into lung health, please follow the link below.
We are excited to announce the publication of our newest paper Membrane Diffusion Occurs by Continuous-Time Random Walk Sustained by Vesicular Trafficking, published in Biophysical Journal. In this paper we investigate the diffusive process that mediates the movement of proteins on the cell surface, and demonstrate a key role of endocytosis and exocytosis in maintaining diffusion within the cell membrane.
Goiko M, de Bruyn JR, Heit B. Membrane Diffusion Occurs by Continuous-Time Random Walk Sustained by Vesicular Trafficking. Biophysical Journal. Volume 114, Issue 12, 19 June 2018, Pages 2887–2899.
If you do not have access to the paper, the final author version is available for free as a preprint at Biorxiv.
I’m excited to announce the publication of our latest paper which investigates the mechanisms by which membrane diffusion and vesicular trafficking contribute to the movement of proteins on the cell surface. https://t.co/GwMUAWPyJB
— Bryan Heit (@BryanHeit) June 19, 2018