S100A9 and dry eye syndrome: It was previously shown that IL-17 can upregulate the cutaneous expressions of IL-1β, hBD-2, CAMP, S100A7, S100A8, S100A9, LCN2, CCL2, CCL20 (24, 42), and KRT17 (39, 41) at the mRNA level detected by microarray and RT-PCR as well, whereas it can downregulate LOR in KCs (42).