Thursday, May 15, 2008


I had been mystified by this subfield until now, and it is profoundly relevant to research of neurological disease, both somatic and psychological:

The brain is extremely immune-protected, since there is a blood-brain barrier made by the glia surrounding our neurons (astrocytes). Very few substances get through the blood-brain barrier, and the molecules that get through produce some interesting effects, but viruses and bacteria which enter the nervous system are acted on by molecules which also affect the nervous system - in a sense, these molecules possess a double duty , particularly cytokines and chemokines.

Psychoneuroimmunology, in particular, is very interesting. It focuses on the 'mind-body connection', which is largely a lot of stuff about placebos and nocebos and how attitude affects your immune system and things of such ilk. What I'd like to see psychoneuroimmunologists address is microbes and mental illness.

As stated before, viruses and bacteria can cause mental illness - schizophrenia might be caused by a virus. I know little of how the blood-brain barrier is formed, but presumably, for example, if a pregnant woman has a virus, it might be easier for it to cross the BBB and wreak all sorts of shit.

I am not sure about how encephalitis and other brain-affecting disorders affect the neuroimmune system, but there seems to be a major role filled by cytokine RNA in detecting it. Cytokines, for those of you who don't know what they are, are proteins that are used in cellular signaling. Activation of them can affect sleep and disposition, and their actions are controlled to an extent by psychological triggers. Presumably, this is probably the biological basis of 'laughter is the best medicine' and other sorts of adages which are the same in meaning.

The entire immunological makeup of a person, however, will affect the brain. Human Genome Sciences, for example, is developing a treatment called belimumab, a human monoclonal antibody, for the treatment of lupus. Lupus has neurological symptoms, among them seizures, psychosis, and abnormalities of the CSF. Given the fact that lupus is triggered by environmental factors, belimumab should be effective in minimizing the development of lymphocytes which act against the body; specifically, it inhibits the b-lymphocyte stimulator. Given the interaction of lupus with the nervous system, one can make a few inferences about how this drug might act: the drug will keep B cells from interacting with the cytokines and chemokines in the nervous system, since it will reduce the B cell count, and reduces the amount of harmful B cells in the cerebrospinal fluid (since the CSF acts as immunological protection).

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