Porcine cathelicidins and defensins

Hundreds of antimicrobial peptides (AMP) have been described in vertebrates, invertebrates, plants and even fungi. The present article describes the cathelicidins and defensins of pigs. Antimicrobial peptides possess direct antimicrobial activity against a wild spectrum of microorganisms (bacteria, fungi, viruses ect.) and the ability to modulate immunological response. The activity of AMP consists mainly in disrupting the microbial membrane. Defensins and cathelicidins are two main classes of AMP. To date, several AMP have been isolated from porcine tissues. The presence of AMP was confirmed in the bone marrow, tongue, trachea, kidneys, reproductive tract, urinary tract and small intestine. Porcine cathelicidins are the first cathelicidins isolated from mammals. So far, eleven porcine cathelicidins have been described: PR-39 (proline-rich 39-amino-acid peptide), PF-1 (proline-phenylalanine-rich prophenin-1), PF-2, cysteine-rich proteins called protegrins (PG) (from PG-1 to PG-5), three porcine myeloid antimicrobial peptides PMAP-23, PMAP-36 and PMAP-37. As yet, no alpha-defensins have been found in pigs; however, thirteen isoforms of porcine beta-defensins (pBD) have been identified, including pBD-1, -2, -3, -4, -104, -108, -114, -123, -125, -126, -129 and pEP2C and pEP2E. In recent years, when the increasing bacterial resistance to antimicrobial agents has been observed, the studies of AMP are necessary, especially with respect to their role as an alternative to antibiotics.