CREEPING INTO YOUR HEAD – A BRIEF INTRODUCTION TO MICROGLIA

By | January 24, 2007 | archive, commentary, textbook

Know anyone with a brain? Know anyone with a problem with their brain?

If you answered yes or no to either or both of those questions, you need to know about microglia. More importantly, however, you need to know about them in order to alleviate my distress. It’s a sucking burden to over and over have it come out at the grocery store that I am a microgliologist and to have no one know what I just said. Not ever. Always just a cocking of the head and a stifled pursing of the lips.

So, what are microglia? They are a type of immune cell that hangs out in our brains. Microglia are known as facilitators, fixers, fighters, and fomenters. At least, in my teaching presentations I call them that – they are the f-words of your brain and mine. To elaborate, microglia facilitate normal development and happy brain function, fix problems, and fight disease, but also sometimes foment bad juju as in Alzheimer’s disease, cancer, stroke, brain injury, schizophrenia, fetal alcohol syndrome, etc. That last f-word, by the way, also explains why you need to know about microglia – it’s a citizenship issue and you need to help humanity fight such bad juju. Thus, if, for instance, you are on a grant issuing board and a proposal for research on microglia comes up, you will now be able to say, “Ah, I know microglia. They are important for normal brain and for fighting pathology of the brain. Give her the cash.”

Now, I am not going to get into a lot of detail about microglia here, as all I really want you to know I already said – they exist and are important in the fight against pathology of the brain. But that doesn’t even reach 300 words, so I can flesh this piece out a bit by mentioning that these teeny immunoinflammatory cells don’t just live in but also constantly move around in our brains. I am, in fact, rather tormented by the knowledge that my brain is a blob of jello riddled with these crawling and climbing, creeping and blorping entities. But I take comfort in the fact that so, too, is your brain, your dog’s brain, your slug’s brain, and, for those of you in Nunavut, your caribou’s brain.

I should also mention that I say they are teeny but that is only relative. Microglia are much smaller than most of the mainstream, Hollywood brain cells such as the rather well-known neuron, for instance. But you probably already guessed something like that based on the name, no? “Micro”, of course, means puny. But “glia”, as you may not know, means glue. Glia is the name given to several types of cell in the brain that aren’t neurons. And that’s all microglia are. Tiny glue holding your head together. The end. Nothing to it. Good ole glia. Who cares. Icky, sticky, gluey, glue, glue.

Ok. So maybe you detected a note of hostility there. The fact is, glia were historically considered mere support cells, and it was once said that glia fill the spaces between neurons. But it has since been argued that perhaps it is just as well said that neurons fill the spaces between glia.

Why were glia and microglia in particular relatively neglected in science? I mean, brain development, brain function, immune and inflammatory goings on in the brain, are pretty important things to know about, are they not? Well, it’s not that microglia were too well hidden to be found until lately. Nope. Microscopists peering into light microscopes found microglia in brain tissue in the late 1800s. And its not that they were really boring and static entities. Rather. Microglia can not only move around but also change back and forth from amorphous blobs that fight disease to cells with multiple highly branched thingies sticking out of them – very funky looking, in fact – that constantly watch over your brain. Despite their amazingness, however, microglia just sort of faded out of the important people’s interest sphere and it wasn’t until about a hundred years had passed since their discovery that really good staining methods for detecting microglia were finally developed and folks started really taking them seriously.

Moreover, the cardinal signs of inflammation we all know and love (redness, swelling, heat, and pain) are difficult to apply to the CNS and it was not until the latter part of the 20th century that modern science even fully recognized immunoinflammatory activity in the central nervous system. So, these fine and upstanding cells, brought to light then thrust back into darkness, were orphaned, waiting for a hundred years between the fronts of neuroscience and immunology, until they were properly claimed by the emerging field of neuroimmunology.

So. Now you know. When we meet in the dairy section, and you ask what I do, I will say what I say and you will say in response, “Ahh. I know microglia. They are vital and dynamic immunoinflammatory cells in the brain. They were ignored for a time in science but have been reclaimed in a conceptual revolution embracing the importance of immune and inflammatory activity in the CNS and are increasingly being seen as targets for therapeutic intervention in many human diseases.” And I will cock my head and neatly purse my lips.

About audreykarperien

The author is a freakin microgliologist, ok?