A recent article in the Science Daily reports on a study that demonstrated in detail how the human immune system located in the brain is altered during certain diseases such as multiple sclerosis. The researchers who participated in the study were from Freiburg, Göttingen, Berlin, Bochum, Essen, and Ghent (Belgium). The study was originally published in the scientific journal Nature.
The scientists used a new, high-resolution method for analyzing single cells. They discovered that phagocytes, a cell of the brain immune system, have the same signature core. However, their function determines how they adapt.
About Phagocytes and Microglia
Phagocytes were known as “the so-called microglia”. Scientists assumed that phagocytes were another type of microglia. They were also uncertain as to whether there are subtypes of microglia associated with the various functions they serve either in the diseased brain or in the healthy brain. The scientists determined that only a single form of microglia is present, but in different permutations.
Prof. Prinz explained that the immune cells are versatile and can adapt to different roles instead of specializing.
As the major cellular component of the innate immune system in the central nervous system (CNS), microglia are the first line of defense whenever injury or disease occurs.
Microglia are the brain’s own immune defenses. This is critical because the regular immune cells of the bloodstream cannot cross the blood-brain barrier or reach the spinal cord.
Results of the Study of Microglia
Microglia cells represent about ten to fifteen percent of all cells in the brain. These cells act as the first line of active immune defense in the central nervous system.
Detailed studies on microglia in the brain were conducted by researchers led by Prof. Prinz. The studies analyzed a animal model and also analyzed human tissue samples from patients. The researchers were able to demonstrate the features of microglia by using a distinct method for cell analysis.
The researchers, using these single-cell analyses, studied microglia throughout their development and in various areas of the brain. Even though the cells shared a single core signature, they nevertheless performed different roles at different development stages. They adapt differently depending upon their location and this adaptation depends upon function.
Limiting Damage in MS, Alzheimer’s, and Autism
If microglia should become dysregulated they can produce high levels of pro-inflammatory and cytotoxic mediators. This can disrupt central nervous system repair and will create neuronal dysfunction and cell death.
Dysregulated microglia can appear with brain diseases such as multiple sclerosis (MS), Alzheimer’s, and several psychiatric diseases, including autism.
Microglia surround the neurons with a uniform network in a healthy brain. New phagocytes are formed in a matter of minutes to limit damage if disease should strike.
Research with MS patients has revealed microglia with unique characteristics and future research with other diseases will continue to focus on how they are altered in different diseases.
Although the mouse model studies were productive, and the scientists recognize the flexibility of microglia, co-author Dr. Masuda acknowledges the complexities of human microglia.