Paneth Cell α-Defensins from Rhesus Macaque Small Intestine

Open Access
Publisher Website
Google Scholar
Abstract
Antimicrobial peptides are secreted by small intestinal Paneth cells as components of innate immunity. To investigate the role of α-defensins in enteric host defenses in nonhuman primates, α-defensin cDNAs were isolated, α-defensin peptides were purified from rhesus macaque small bowel, and the bactericidal activities of the peptides were measured. Six rhesus enteric α-defensin (RED) cDNAs, RED-1 to RED-6, were identified in a jejunum cDNA library; the deduced RED peptides exhibited extensive diversity relative to the primary structures of rhesus myeloid α-defensins. RED-4 was purified from monkey jejunum, and N-terminal peptide sequencing of putative RED-4 peptides identified two N termini, RTCYCRTGR… and TCYCRTGRC…; these corresponded to alternative N termini for the RED-4 molecules, as deduced from their molecular masses and RED cDNAs. In situ hybridization experiments localized RED mRNAs exclusively to small intestinal Paneth cells. Recombinant RED-1 to RED-4 were purified to homogeneity and shown to be microbicidal in the low micromolar range (≤10 μg/ml) against gram-positive and gram-negative bacteria, with individual peptides exhibiting variable target cell specificities. Thus, compared to myeloid α-defensins from rhesus macaques, enteric α-defensin peptides are highly variable in both primary structure and activity. These studies should facilitate further analyses of the role of α-defensins in primate enteric immunity.