Spectrum Library

There is evidence that the presence of Aquaporin-4 is directly involved in the pathogenesis of NMO. AQP-4 Ab is thought to bind to an extra-ceLlular domain of the target protein and the E-loop was suggested as a probable candidate epitope. Molecular mimicry namely structural similarity between epitopes contained within microbial and host proteins, leading to cross-reactive Ab’s in the host has been discussed. These authors preformed a “BLAST” search for bacterial and viral proteins sharing homology with loop E of AQP-4.The Klebsiella Pneumoniae (kpsp) transmembrane protein KPN-pKPN 3p05929 produces significant alignment with loop E of AQP-4. Kpsp infection is not rare, an immunity to Kpsp has been implicated in the etiology of Ankylosing spondylitis and Crohn’s disease. It was therefore postulated that K Pneumoniae may playa role in the pathogenesis of NMO. These studies however do not provide a major role of Kpsp infection in the development of NMO. The authors do not rule out the fact that the epitope of AQP-4 Ab could be conformational rather than linear The homology does not imply structural homology, and the latter approach would be arduous and challenging to proof.

Read More: Homology between Klebsiella pneumoniae and human aquaporin-4: no evidence for cross-reactivity in neuromyelitis optica. A study on 114 patients.