Seven of the 15 studies reported that patients were infected with CagA-positive strains of H. pylori [16, 17, 19, 21, 22, 26, 30], of which four studies [16, 21, 22, 26] showed that the infection was significantly associated with AITD, and three studies demonstrated no correlation between the infection and AITD [17, 19, 30]. Here, S100A8 is linked to infection.