An isolated and purified peptide, neonatal NET-inhibitory Factor (nNIF), is disclosed. Methods for treatment of and prophylaxis against inflammatory disorders are also disclosed, including methods of treatment of and prophylaxis against inflammatory disorders comprising administering NET-inhibitory peptides (NIPs), which may be a nNIF, a pharmaceutically acceptable salt of a nNIF, a nNIF analog, a pharmaceutically acceptable salt of a nNIF analog, a nNIF-Related Peptide (nNRP), including the nNRP, Cancer-Associated SCM-Recognition, Immune Defense Suppression, and Serine Protease Protection Peptide (CRISPP), a pharmaceutically acceptable salt of a nNRP, a nNRP analog, or a pharmaceutically acceptable salt of a nNRP analog, to an individual.