Paneth Cell -Defensins from Rhesus Macaque Small Intestine

Antimicrobial peptides are secreted by small intestinal Paneth cells as components of innate immunity. To investigate the role of -defensins in enteric host defenses in nonhuman primates, -defensin cDNAs were isolated, -defensin peptides were purified from rhesus macaque small bowel, and the bactericidal activities of the peptides were measured. Six rhesus enteric -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 -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 g/ml) against gram-positive and gram-negative bacteria, with individual peptides exhibiting variable target cell specificities. Thus, compared to myeloid -defensins from rhesus macaques, enteric -defensin peptides are highly variable in both primary structure and activity. These studies should facilitate further analyses of the role of -defensins in primate enteric immunity. In mammals, antimicrobial proteins (AMPs) and peptid