C3AR1 and Alzheimer disease: [49, 61] A new study shows that H. pylori OMV may contribute to the onset of Alzheimer's disease (AD) through complement component C3a receptor (C3aR) signaling.[62]H. pylori OMVs could enter the brain via a transcellular pathway crossing the barriers or indirectly via the vagus nerve[63] and increased the compactness and surface area of Aβ plaques in mice, which is an important pathological features of AD.