The Role of Microglia in the Brain

As more and more research is being done on the brain and its structures, we are discovering that there may be more significant elements that play key roles in its function than previously thought. One of these elements is microglia. Apart from its commonly known role as the scavengers of the brain and one of its first lines of defense, microglia are also involved in inducing cell death, promoting tissue repair, and other types of development. Many research studies are underway to explore these seemingly newfound functions of microglia that are specifically focused on how they are involved in development, repair, and diseases in the brain.
One research study done by Ukpong B. Eyo and Michael E. Dailey looks at the role of microglia. In this study, the researchers look at microglia as the often overlooked ‘3rd element’ of the nervous system working alongside other key structures such as neurons and astrocytes. In the article Microglia: Key Elements in Neural Development, Plasticity, and Pathology, it details microglia as having a wide range of functions in the brain including migrating to injuries, induction of cell neuronal death, phagocytic clearance of cellular debris, the monitoring of the functional states of synapses. One particularly significant point the article mentions is that it was previously thought that in uninjured brain tissue microglia were nonmotile. This notion was later overturned with the discovery that even in healthy tissue, the microglia are very motile just not migratory. This discovery means that microglia in the “uninjured adult CNS are motile, non-migratory cells functioning to persistently survey the CNS to detect aberrations”. Though they do respond to injuries in brain tissue, even in normal tissue, they are not simply stationary and inactive. Furthermore, this leads to the idea that microglia are not just activated when there are injuries in the brain they actually have proactive role in the maintenance of the brain that was previously not known.
Similarly, another study ,detailed in the article Rise of the Microglia, discusses the work of the researchers at the European Molecular Biology Laboratory and their study on microglia. This article talks about another newly discovered function of microglia which is their role in synapse sculpting. This means that as the brain is developing in vivo, microglia are critical to this process as they “they gobble up synapses, thus helping to sculpt the brain by eliminating unwanted connections.” Though this provides important insight into the development of the brain, it also raises questions about what can occur if this sculpting process goes wrong. Specifically, the article mentions that “studies have also found evidence for increased microglial activation in individuals with schizophrenia and autism” though the exact cause behind these disorders are unknown. This means that microglia could possibly be looked at in terms of assessing reasons for a certain disease and even potential treatments for them. By understanding that these structures have a key role in development, it brings to light the fact that there is so much that still may be unknown about how the brain develops.
When looking at and comparing these two studies, it is important to think about how recent so many of these discoveries are. Previously, the functions that are not attributed to microglia were most likely not fully understood or were overlooked. There are so many aspects of the brain and nervous system that scientists still do not completely understand, leading to the idea that there may be other structures in the brain that have yet to be discovered. Though both articles touch on the fact that these discoveries may lead to treatments involving microglia, an actual therapeutic use of these structures has yet to be created. We can be hopeful, however, that as we learn more and more about these defenders of the brain, a treatment for many disorders involving microglia may be just on the horizon.