Sarah explores the latest research on astrocytes, gut bacteria and neuroinflammation with scientist and medical researcher Dr. Francisco Quintana.
Dr. Quintana is a Professor of Neurology at Harvard Medical School and an Associate Scientist at Brigham and Women’s Hospital in Boston, Massachusetts. He describes some of the causes of neuroinflammation including infection, tumours and auto-immune disease. So what does all of that have to do with astrocytes?
Astrocytes are a type of glial cell found in the central nervous system. These cells were first described over 100 years ago and were given their celestial name because they are shaped like a star. Even though they are the most abundant type of cell in the brain, Dr. Quintana points out that we are just now beginning to understand their function. One of the important functions of the glymphatic system is in regulating the movement of fluids in and out of the brain. Once seen as having more of a supportive role in the brain, astrocytes are now understood to help regulate inflammation – an important finding in the study of diseases such as Multiple Sclerosis, Alzheimers and Parkinson’s disease. In fact, Dr. Quintana states that the astrocytes can, “boost and drive inflammation and that’s very important because, so far, we have no therapies to actually suppress those pro-inflammatory activities.”
“All in all, I think this shows how complex systems that, from the distance seem to be completely unconnected…the bacteria, the gut and the brain…but our data shows how closely they are connected and by doing so, then it highlights how much we have to learn about, not only how those connections operate, but also how we can manipulate those connections as a way of having new therapies for important diseases.”Dr. Francisco Quintana
Neuroinflammation and gut bacteria
What does gut bacteria have to do with our brains? Dr. Quintana explains that research is showing that some chemicals produced by gut bacteria, metabolites, go to the brain and act directly on the astrocytes. These bacteria also send signals, through the nervous system, to the astrocytes to activate anti-inflammatory processes in the brain. Dr. Quintana describes how astrocytes can act as gatekeepers for the brain, determining not only what can transfer from the circulatory system into the brain, but also sending out signals based on information carried in the blood.
“We’re starting to appreciate that actually, astrocytes can boost and drive inflammation and that’s very important because so far, we have no therapies to actually suppress those pro-inflammatory activities.”Dr. Francisco Quintana
Although some astrocytes are helping to keep our brains safe and healthy, another subset of astrocytes act in ways that are considered pathogenic – leading to neuroinflammation or even the death of neurons (neurodegeneration). Because of this, certain types of astrocytes are implicated with specific diseases. Dr. Quintana’s research examines the ways to reduce the activity of the harmful subsets of astrocytes while boosting those types that have helpful properties. He notes that being able to target different types of astrocytes is an important step in regulating their activity.
Dr. Quintana describes other research that looks at how various microbiome environments, including the microbiomes of patients with various diseases, contribute to pathogenesis in those types of patients. He is currently researching the anti-inflammatory properties of astrocytes and how they may be utilized in preventing neuroinflammation, how they communicate with other parts of the body, how they are influenced by the gut flora, and how certain molecules can be targeted to treat diseases. Dr. Quintana’s team continues to explore the interconnections that are being discovered through research and hopes that these discoveries can be applied to new therapies for treating various diseases. Thank you Dr. Quintana for your dedication to this important research and for seeking out new therapies for neuro-inflammatory diseases!
“We started to use new techniques to actually be able to look into different subsets or classes of astrocytes and indeed that led us to identify very recently a class of astrocytes…involved in dampening inflammation. This is a protective subset.”Dr. Francisco Quintana
Sanmarco, L.M., Wheeler, M.A., Gutiérrez-Vázquez, C. et al. Gut-licensed IFNγ+ NK cells drive LAMP1+TRAIL+ anti-inflammatory astrocytes. Nature 590, 473–479 (2021). https://doi.org/10.1038/s41586-020-03116-4