LCN2 and depressive disorder: Lipocalins are elevated and released during inflammation 56, infections 57 and sepsis 58, 59, 60, especially when the urinary tract is affected in humans and dogs 61, 62; in cardiovascular inflammation they get overexpressed in the brain and linked with depression 63; in cancer LCN2 is overexpressed 11, 64 prompting interaction with metalloproteinase‐9 (MMP‐9) 65, but only LCN2 is prognostic 66.