I am thinking the pathogenesis of the C5a in GBS. I think the pathogenesis happens like
C5a-peptidase in acid environment (Sialic acid, capsule) $\to$ cleaves C'-derived Neu chemoattractant C5a $\to \downarrow$ alternative pathway of Complement.
However, this part cleaves C'-derived Neu chemoattractant C5a is not clear to me. I think this means that C5a-peptidase cleaves Neu C5a from the previous complement reaction that inhibits the next coming alternative pathway of complement.
How does this pathogenesis of GBS happen?