According to ScienceDaily, the architecture of its neural networks and underlying biological processes and structures that underpin them are notoriously difficult to extract from the human brain. Scientists can now undertake in-depth investigations of the live brain due to recent advances in neuro-imaging and molecular biology, revealing insight into previously inexplicable phenomena.
This novel component of the brain’s architecture, which defends the brain from viruses and inflammation while also providing immune cells with a vantage point to watch brain activity, was published today in science. The meninges are three membranes that cover and protect the brain and spinal cord. The dura, arachnoid, and pia mater are the three. The subarachnoid region in both the mouse and human brains is divided by a fourth meningeal layer, which we call the subarachnoid lymphatic-like Membrane (SLYM).
SLYM resembles the mesothelial Membrane that borders peripheral organs and body cavities in form and immunophenotype because it encloses blood veins and contains immune cells. SLYM operate similarly to arachnoid granulations in the mouse due to their closeness to the endothelial lining of the meningeal venous sinus, permitting the direct exchange of minute solutes between cerebrospinal fluid and venous blood.
Understanding the underlying processes of SLYM activation aids in the resolution of fundamental questions concerning the brain’s immunological defenses and fluid transport. Kjeld Mllgrd, M.D., a professor of neuroanatomy at the University of Copenhagen, and Maiken Nedergaard, co-director of the Center for Translational Neuromedicine at the University of Rochester and the University of Copenhagen, collaborated on this recent study.
Nedergaard and her colleagues have significantly enhanced the understanding of the brain’s basic mechanics by exposing the brain’s unique waste clearance function, dubbed the glymphatic system, and the myriad necessary actions of brain cells known as glia.
According to Nedergaard, cerebrospinal fluid (CSF) plays a complicated role in conveying and eliminating waste from the brain and maintaining its immunological defenses. He also mentioned the discovery of a novel anatomic structure that segregates and helps control the flow of CSF in and around the brain.
Because they keep the brain wet, cerebrospinal fluid and the membranes surrounding it are being researched (CSF). The dura, arachnoid, and pia matter make up the meningeal layer.
The Subarachnoidal Lymphatic-like Membrane is a newly discovered layer that divides the subarachnoid space (found underneath the arachnoid layer) into two extra compartments (SLYM). The study focuses mainly on SLYM function in mice but also reports finding SLYM in the human brain.
The SLYM is composed of the mesothelium, which may also be found lining other organs such as the lungs and heart. Mesothelium, which is found around organs, protects them and serves as a home for immune cells. Mllgrd, the paper’s lead author, postulated the presence of a comparable membrane in the brain. His study focuses on developing the brain’s defenses at different stages of life.
The nascent Membrane is readily disrupted since it is only a few cells thick. On the other hand, the SLYM is a highly impermeable barrier that appears to differentiate “clean” from “dirty” CSF by allowing only the smallest molecules to get through.
Finally, this finding suggests that SLYM may function in the glymphatic system, which relies on the continual flow and exchange of cerebrospinal fluid (CSF) to bring in new CSF while flushing away harmful proteins associated with Alzheimer’s disease and other neurological illnesses. The glymphatic system is currently the subject of a $13 million study financed by the National Institutes of Health’s BRAIN Initiative, and our findings will help that inquiry.
According to studies, the SLYM is essential in avoiding brain injury. The CNS has its own resident immune cell population, and the Membrane’s integrity prevents immune cells from invading the CNS. As if that weren’t enough, the SLYM has its population of central nervous system immune cells that utilize it for surveillance near the brain’s surface, looking for indications of infection in circulating CSF.
The discovery of SLYM opens the door to future research into its function in neurodegenerative illnesses. The researchers discovered, for example, that inflammation and aging both increases the quantity and kind of immune cells converging on the Membrane. When cerebrospinal fluid (CSF) flow is interrupted, immune cells from the circulation can reach the CNS and cause injury.
These findings imply that SLYM dysfunction may have a role in the start or progression of various illnesses and ailments, including but not limited to M.S., CNS infections, and Alzheimer’s disease. They also imply that SLYM function may alter medication and gene therapy delivery to the brain, which will need to be considered when constructing the next generation of biological medicines.