A zebrafish specimen. Image courtesy of Wikimedia.
life sciences
Neuroimmunology: A Dialogue Between Two Crucial Systems Andrew Prevatte The human body constantly collects information about its environment, sending signals, and commanding actions through an intricate network known as the nervous system. A flaw or short-circuit in the nervous system could mean catastrophe for the rest of the body. The vital importance of such a widespread system is what piqued Dr. Celia Shiau’s interest, which led her to study another crucial body system and eventually, one of the most versatile and extensive cell types in the body. Dr. Shiau works within the dynamic field of neuroimmunology, a subfield of molecular Dr. Celia Shiau biology which examines the interaction between the nervous system and immune system, the body’s defense against infection. These two networks are often intertwined; when the nervous system is disrupted by disease, the immune system usually responds in defense. Knowing how these two systems interact can lead to a better understanding of how homeostasis, or bodily equilibrium, is maintained across the body. One particular component of the immune system is of interest to Dr. Shiau: macrophages. Macrophages, which are big “cell eaters” that help clean up cellular debris across the body, are involved in signaling and have been implicated as impacting the connections between neurons. Dr. Shiau’s states, macrophages are a “very unique and phenomenal cell type that is versatile and dynamic.”1 Fully understanding the inner workings of macrophages would allow for major developments in immunotherapy, with widespread applications, including cancer remission. Macrophages reside in every tissue across the body, performing a myriad of different functions. In fact, they can change morphology and behavior in
response to a small change in their microenvironment. The unique sensitivity makes macrophages well-equipped for their environment in the brain, the hub of the nervous system. Macrophages that reside in the brain are known as “microglia.” Dr. Shiau specifically examines microglia, due to their unique nature of being the only type of immune cell residing in the brain.1 Much is still unknown about microglia, but Dr. Shiau’s lab is determined to develop a better picture. What are the molecular controls that regulate activity of microglia? What genes are involved in the development of microglia, or the lack of them? What does a loss of microglia look like — are there structural changes in the brain, or consequential impacts on animal behavior? These are the questions about microglia which currently interest Dr. Shiau.
Figre 1, left: Macrophage of a mouse phagocytosing Figure 2, right: Microglia (green) and neurons. Images courtesy of Wikimedia.
In order to observe and test macrophages, Dr. Shiau uses an interesting organism, the zebrafish. Zebrafish processes bear remarkable similarities to human processes, as their tissues, organs, and cell types are highly conserved from fish to human. However, it is not only the applicability of results that drew Dr. Shiau to study this model organism. Zebrafish also have high optical transparency, meaning that the inner workings of their tissues
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