Devic disease, also referred to as neuromyelitis optica or NMO, is known as an immunological disorder that is frequently misdiagnosed with multiple sclerosis (MS). Devic disease is often characterized by immune attacks on the optic nerves and the spinal cord. Anti-AQP4 autoimmune antibody has been regarded as responsible for the development of Devic disease.
On the other hand, AQP4 is a well-known water channel in the central nervous system where it participates in cerebral water balance and induces brain edema with damaged BBB. That is why it seems to be paradoxical why auto-immune reaction against AQP4 does cause the inflammation in the central nervous system in Devic disease...
Anti-AQP positive variants of Devic's disease is similar to multiple sclerosis in that, the immune system attacks the myelin. Unlike MS these attacks are not mediated by T-cells, but by the antibodies called Anti-AQP4-IgG, which targets the AQP4 in astrocytes membrane.
In addition to this, the inflammation's pattern in Decic's dusease is different from MS which has a perivascular distribution.
Like MS, Devic's disease leads to loss of myelin and can cause attacks of optic neuritis and myelitis. However, Devic's disease is different from MS in the severity of its attacks and its tendency to solely strike the optic nerves and spinal cord at the beginning of the disease. Symptoms outside of the optic nerves and spinal cord are rare, although certain symptoms, including uncontrollable vomiting and hiccups, are now recognized as relatively specific symptoms of NMO that are due to brainstem involvement.
mh. but how can anti-AQP be responsible when AQP is not expressed in endothelial cells? Or do I miss something? the BBB will stay closed, the antibody has no access to the target.
And there are anti-AQP negative NMO cases. If the hypothesis is that NMO is mediated by this anti-AQP, then the existence of negative patients is the falsification of that theory (according to Popper :-p).
To find it in the lesions at the end (if this holds true, it can be just another polyreactive clone binding many proteins) and that it would fit to our "understanding" does not proof anything. Association with severity and progression of disease is missing. sorry guys.
And anti-AQP is a natural antibody, germline encoded. Anybody has anti-AQP4-IgM. Only IgG is associated with the disease in the neuro-group. I would be interested to see data from SLE patients or RA. often the autoantibody theories collapses then.
CD4 T Cells need to be there against AQP4. Otherwise switch to IgG is hard to explain.
don't get me wrong. until now anti-AQP is an important marker for NMO. And the immune system likely plays a role. But I believe a clear clinical picture seen by an experienced neurologist should be the lead.
But to think of anti MBP as important antigen in MS is like: I hit my muscle, get inflammation and wow: I get anti-myoglobin. MBP is the highest abundant protein in the myelin sheeth. and MOG has other problems which but a rol in question.
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