Research

Our lab investigates cell adhesion mechanisms, and how adhesion signaling drives various cardiovascular and inflammatory diseases. In particular, we are interested in studying how leukocytes, especially neutrophils, adhere to blood vessels and trigger inflammation leading to immune disorders. Neutrophils are often the first immune cells to reach sites of inflammation, where they release cytotoxic species that kill bacteria, fungi, and other pathogens. Exacerbated inflammation causes collateral tissue damage and is a strong risk factor for cardiovascular diseases such as inflammatory heart disease and stroke. We strive to gain a comprehensive understanding of the molecular mechanisms of leukocyte adhesion in inflammation.

Molecular mechanisms of leukocyte adhesion and trafficking

Rapid leukocyte recruitment to inflammation sites is highly dependent on the activation of integrins. Integrins are transmembrane receptors that control cell adhesion and migration to inflammatory tissues. Such control is particularly important in the vasculature, where dynamic blood flow physically opposes cell attachment. β2 integrins are expressed in all leukocyte populations. How are β2 integrins activated during leukocyte adhesion? We use flow cytometry, imaging, and genetic intervention tools to delineate molecules underlying leukocyte adhesion in cardiovascular inflammation.

Leukocyte adhesion cascade

Integrin activation at the footprints of neutrophils. Movie: TIRF imaging of neutrophil-like HL-60 cell rolling and arrest under flow. CMDR: cell membrane. TagRFP-K3: kindlin-3 labeled with TagRFP, mAb24-AF488: antibody reporter of high-affinity β2 integrin. Flow direction: top to down. 0 s, cell arrest. < 0 s, cell rolling. > 0 s, cell adhesion. Scale bar, 5 µm.

Visualization of neutrophil recruitment and function during inflammation

Neutrophils circulating in the bloodstream are first captured by the vessel wall, followed by rolling, slow rolling, full activation, and arrest, before transmigration across the vessel wall. In response to inflammation, receptor ligation on the membrane of immune cells is transmitted by intracellular second messengers. We develop and apply tools including reporter mice for cAMP/cGMP/Ca2+ and β2 integrin activation to understand inter- and intra-cellular signaling responding to inflammatory signals.

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β2 integrin activation in vivo. Movie: Mouse neutrophils arrest on the vessel wall in response to CXCL1. Reporter antibodies show extended integrin (red, top) and high-affinity integrin conformation (green, middle). Channel merge shown in yellow (bottom). Purple, neutrophil cell outline.

Engineering immune cells for cancer immunotherapy

Can we harness the immune signaling to develop effective immunotherapy to treat cancer? We aim to push the boundaries of cancer immunotherapy by exploring advanced techniques in engineering immune cells for enhanced and precise targeting of cancer cells. We seek to identify key molecular pathways that can be manipulated to augment the immune response against tumors.

Approaches

We use a variety of approaches to test our hypotheses and to achieve our goals.

● Gene editing and genomic engineering

● Multi-color flow cytometry

● Transgenic mouse models

● Lentiviral and retroviral gene delivery

● Bone marrow transplantation

● Biosensors/probes

● Homogenous antibody binding assays

● Molecular structure/function analysis

● Microfluidics

● High-resolution imaging:

Confocal, super-resolution imaging, live-cell imaging, molecular tracking, TIRF microscopy, FRET microscopy and intravital imaging

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