As we reported in an article yesterday, researchers are becoming increasingly interested in the potential of changing the ratio of types of macrophages present in the body to facilitate tissue regeneration and healing.
This is a line of research that covers a number of topics, including aging, regeneration, tissue repair, and inflammation. Over the last year or so we have seen a number of publications focusing on altering populations of macrophages to elicit repair and regeneration of tissues, which is a positive sign that things are moving forward.
The balance between different types (known as polarizations) of macrophages is again the subject of another study, which we will discuss today. This time the focus is on Parkinson’s disease and how changing the ratio of macrophage types could be a potential therapy for this devastating age-related disease.
Altering macrophage types
Macrophages are derived from monocytes, a type of immune cell which changes into one of a number of macrophage types, depending on local signalling when they arrive at the site of injury or damage.
As discussed in our previous article, the M1 and M2 types of macrophages are again in the spotlight and the potential of changing the ratio of M1 and M2 types is the focus.
M1-type macrophages tend to aggressively destroy problematic cells and cause inflammation when they do so, due to the inflammatory signals they secrete to recruit other immune cells to the site.
The problem is, when there are too many M1-type macrophages present, inflammation becomes excessive and this hinders the repair and regeneration of tissues.
The M2 type of macrophage can be considered a “healing” cell which favours and facilitates the suppression of inflammation as well as promoting tissue regeneration.
Falling costs may be encouraging progress
This increased interest in tweaking macrophage types is likely the result of the arrival of tools that allow for cost-effective approaches to change the ratio of macrophages. Progress in biotechnology is moving very rapidly, thanks in part to falling costs and refined techniques and equipment that make tasks far easier.
One only needs to consider CRISPR as an example of this: what was once a complex and time-consuming laborious process can now be rapidly achieved. The field is filled with similar examples, and these breakthroughs in the tools researchers have at their disposal is fuelling a meteoric rise in research progress.
So onto the research
Researchers in this new study focus on a tissue resident type of macrophage known as microglia, which is present in the central nervous system. Changes to microglia are known to be important in the progression of a number of age-related neurodegenerative conditions, including Alzheimer’s, ALS, and Parkinson’s disease.
As we age, the immune system declines in the central nervous system, as it does in the rest of the body, causing it to become dysfunctional and generating excessive levels of inflammation driving the aging process even faster. This chronic inflammation, often referred to as “inflammaging”, hinders tissue maintenance and repair.
However, microglia have additional functions, such as helping to ensure the correct functioning of neurons and neural connections. In this paper, the researchers explore the idea of changing the ratio of microglia polarization to favour the healing M2 type as a potential way to address Parkinson’s disease.
It is great to see yet more researchers focusing on this area of research, and with the falling costs of the infrastructure of biotechnology, we are hopeful that interest will continue to grow in this area.
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 Subramaniam, S. R., & Federoff, H. J. (2017). Targeting Microglial Activation States as a Therapeutic Avenue in Parkinson’s Disease. Frontiers in Aging Neuroscience, 9, 176.