Are Astrocytes Important for Fighting Inflammation?

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Inflammation is an important part of the body’s defence mechanism towards pathogens but sometimes needs to be stopped or reduced to protect us. This is because inflammation is usually a sign of the body killing pathogens, healing injuries and more positives, effects which are more common with acute inflammation. However, inflammation can be disadvantageous if it is extreme. The reason for that is that inflammation of high intensity or over a long period (chronic inflammation) can damage healthy cells, resulting in tissue death, internal scarring, DNA damage and more. These effects can result in cancer and other diseases, which are not necessarily pathogenic. This why it is important within the body to have anti-inflammatory responses to prevent or stop damage to healthy cells by inflammation.

Usually, astrocytes have not much effect on inflammation. Astrocytes are cells within the brain which are very important in the regulation of neurone development, through their provision of various vital nutrients to these neurones. Although astrocytes are extremely crucial, they can often malfunction, resulting in the promotion of inflammation and neurodegeneration, resulting in diseases like Alzheimer’s and Parkinson’s.

However, what if faulty astrocytes can decrease, not support inflammation in the body? This is what was observed by researchers at Ann Romney Center for Neurologic Diseases, at Brigham and Women’s Hospital, in Boston, MA, USA. The lead researcher, Dr Francisco Quintana, said that his team had found the first case ever of astrocytes, normal and malfunctioned, having anti-inflammatory responses. This group of astrocytes were found in mice, but Dr Quintana is confident that the qualities of this specific astrocyte can be used to reduce and prevent harmful inflammation in humans. Dr Quintana also said that the reason specific differences between astrocytes had not been noticed before is that scientists assumed that all astrocytes had the same structure due to their “uniformity” but this has now been proven to be false.1

What makes these newly found astrocytes anti-inflammatory? The astrocytes in question have genes which express the two proteins LAMP1 and TRAIL. This results in the new astrocytes being called LAMP1+TRAIL+ astrocytes. LAMP1+TRAIL+ astrocytes form near to the meninges, which are the protective membranes enveloping the brain and spinal cord. The TRAIL protein expressed by the astrocyte reduced inflammation, by binding to death receptors within the membranes of immune cells, receptors which increase inflammation. This binding results in immune cells promoting inflammation conducting apoptosis.

Dr Quintana’s team has also discovered why the LAMP1+TRAIL+ astrocyte acts the way it does. Their research showed that the LAMP1+TRAIL+ astrocyte was regulated by the gut microbiome, only one of two types of astrocytes known to be controlled in this particular way. Scientists predict that once it is known the specific mechanism by which the gut flora regulates the LAMP1+TRAIL+ astrocytes, new, more effective, treatments for inflammatory neurological diseases can be found, especially multiple sclerosis. Despite how promising this research is, it should be recognised that so far gut flora is shown to affect some astrocytes in mice, and although this should be the same in humans, it is not definite.2

Even so, it is very encouraging to see how extreme and chronic inflammatory responses may be able to be reduced in the future in humans by controlling the environment of the astrocytes, which can indirectly regulate the action of the astrocytes.


References

  1. ScienceDaily. 2021. Newly discovered subset of brain cells fight inflammation with instructions from the gut. [online] Available at: <https://www.sciencedaily.com/releases/2021/01/210125191812.htm> [Accessed 29 January 2021].
  2. The Human Memory. 2021. Astrocytes | Facts, Functions, Structure, Types & Repair. [online] Available at: <https://human-memory.net/astrocytes/> [Accessed 29 January 2021].

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