11:00 am–12:00 pm
Please Join us:
Elizabeth Mulder's PhD Thesis Defense
Wednesday, April 19, 2023 at 11:00 am CDT
PROBING INDIVIDUAL AND COLLECTIVE MACROPHAGE RESPONSES WITH FLUIDIC FORCE MICROSCOPY
Macrophages play a central role in the immune response by monitoring for signs of infection and then initiating a wider response. This immune response needs to be proportionate to the threat; both over-responding and under-responding are potentially dangerous to the body. The number of macrophages that activate, the degree and duration of their responses, and the types of signals they generate may all impact the downstream immune response. However, not all macrophages respond identically even to a uniform stimulus, and macrophages residing in tissues likely encounter localized and/or transient signals to which individual cells may respond differently depending on their context, history, cell state, etc.
Within this complex environment, how do macrophages calibrate their individual and collective responses to correctly match their response to the threat? Answering this question is difficult with traditional experimental techniques that either treat an entire culture or isolate cells from their environment. Fluidic Force Microscopy (FluidFM) combines the precision control of Atomic Force Microscopy (AFM) with a pneumatic system capable of delivering picoliter volumes of liquid through a hollow AFM probe. FluidFM stimulation targets cells on their length-scale, allows simultaneous live cell monitoring, preserves environmental context, and gives the user precise control over the location, concentration, and duration of stimulation.
Using the FluidFM, I determined the minimum conditions in concentration and time for activation of single macrophages via TLR stimulation, compared single, small group, and whole culture stimulation, and found a dependence on culture density in modulating the group response. I built a model to determine the stimulus gradients produced by FluidFM dispensing and how it related to the spatial limits of the macrophage group response. Lastly, I developed a method to investigate whole pathogen-macrophage interactions with the FluidFM, in order to determine the physical parameters that are necessary to generate an immune response. This research advances our knowledge of how macrophages, singly and collectively, modulate their responses to signs of infection and environmental factors. These regulation strategies by early-responding cells are one piece of how the whole immune system regulates itself for safe and effective function.
Committee Members:
Aaron Esser-Kahn (Chair)
Margaret Gardel (Department Sponsor)
Samantha Riesenfeld
David Schmitz