PGLYRP1, also known as tumour antigen 7 (tag7) protein or PGRP-S, is another member of the mammalian PGRP family and is highly expressed in immune cells such as neutrophils, macrophages and eosinophils [50] and has been linked to several inflammatory conditions like rheumatoid arthritis [51], airway inflammation [50], coronary artery disease [52–54], asthma [55,56], oral inflammation [57–60] and cancer [61]. Here, PGLYRP1 is linked to rheumatoid arthritis.