This invention relates to polypeptides, including variants of interleukin-37 (IL-37), and related therapeutics and compositions. The invention also relates to the use of the polypeptides and compositions in methods of treating inflammatory diseases or conditions. The present invention provides a monomeric anti-inflammatory polypeptide comprising an amino acid sequence of an IL-37 monomer, the amino acid sequence having a mutation or modification for preventing the anti-inflammatory peptide from forming a homodimer.