We hypothesized that LCN15 may contribute to the prevention of infection in the olfactory mucosa because (1) LCN2 is known to exhibit bacteriostatic effects by binding bacterial siderophores and depriving iron of the bacteria28, and (2) olfactory mucosa is a direct infectious pathway from the nasal cavity to the brain, and may therefore have a unique preventive system against bacterial infection. Here, LCN2 is linked to infection.