PR-39 coordinates changes in vascular smooth muscle cell adhesive strength and locomotion by modulating cell surface heparan sulfate-matrix interactions

Neutrophil-derived cathelicidin promotes cerebral angiogenesis after ischemic stroke

Neutrophils play critical roles in the evolving of brain injuries following ischemic stroke. However, how they impact the brain repair in the late phase after stroke remain uncertain. Using a prospective clinical stroke patient cohort, we found significantly increased cathelicidin antimicrobial peptide (CAMP) in the peripheral blood of stroke patients compared to that of healthy controls. While in the mouse stroke model, CAMP was present in the peripheral blood, brain ischemic core and significantly increased at day 1, 3, 7, 14 after middle cerebral artery occlusion (MCAO). CAMP-/- mice exhibited significantly increased infarct volume, exacerbated neurological outcome, reduced cerebral endothelial cell proliferation and vascular density at 7 and 14 days after MCAO. Using bEND3 cells subjected to oxygen-glucose deprivation (OGD), we found significantly increased angiogenesis-related gene expression with the treatment of recombinant CAMP peptide (rCAMP) after reoxygenation. Intracerebroventricular injection (ICV) of AZD-5069, the antagonist of CAMP receptor CXCR2, or knockdown of CXCR2 by shCXCR2 recombinant adeno-associated virus (rAAV) impeded angiogenesis and neurological recovery after MCAO. Administration of rCAMP promoted endothelial proliferation and angiogenesis and attenuated neurological deficits 14 days after MCAO. In conclusion, neutrophil derived CAMP represents an important mediator that could promote post-stroke angiogenesis and neurological recovery in the late phase after stroke.

Proline-arginine rich (PR-39) cathelicidin: Structure, expression and functional implication in intestinal health

Proline-Arginine-39 (PR-39) is a small cationic, proline and arginine rich, cathelicidin that plays an important role in the porcine innate immune system. Although PR-39 was first discovered in intestinal cell lysates of pigs, subsequent research has indicated that it is primarily expressed in bone marrow and other lymphoid tissues including the thymus and spleen, as well as in leukocytes. Mature PR-39 cathelicidin has anti-microbial activity against many gram-negative and some gram-positive bacteria. PR-39 is also a bridge between the innate and adaptive immune system with recognized immunomodulatory, wound healing, anti-apoptotic, and pro-angiogenic functions. The purpose of this review is to summarize our current knowledge about the structure, expression, and functions of PR-39 and its potential to promote intestinal homeostasis. This understanding is relevant in the search of alternative therapeutics against diarrheic enterocolitis, a major problem faced by pork producers both in terms of costs and risk of zoonosis.

Cathelicidins in inflammation and tissue repair: Potential therapeutic applications for gastrointestinal disorders

Cathelicidins, a family of host defense peptides, are highly expressed during infection, inflammation and wound healing. These peptides not only have broad-spectrum antimicrobial activities, but also modulate inflammation by altering cytokine response and chemoattraction of inflammatory cells in diseased tissues. In this connection, a mouse cathelicidin has been demonstrated to prevent inflammation in the colon through enhancing mucus production and reducing production of pro-inflammatory cytokines. In addition, cathelicidins promote wound healing through stimulation of re-epithelialization and angiogenesis at injured tissues. In an animal model of gastric ulceration, the rat cathelicidin promotes ulcer healing by inducing proliferation of gastric epithelial cells both in vitro and in vivo. In conclusion, cathelicidins represent an important group of effector molecules in the innate immune system that operates a complex integration of inflammation and tissue repair in the gastrointestinal mucosa and other organs.

Expression and purification of two different antimicrobial peptides, PR-39 and Protegrin-1 in Escherichia coli

To implement coexpression of antimicrobial peptides PR-39 and Protegrin-1 (PG-1) in prokaryotic expression system, a tandem gene fragment encoding PR-39 and PG-1 has been synthesized chemically. The cleavage site (Asn-Gly) of hydroxylamine hydrochloride was introduced between PR-39 and PG-1. The fragment was inserted into vector pGEX-4T-1 and expressed in Escherichia coli. The fusions of single peptides to GST were created at the same time. The fusion protein GST-PR-39-PG-1, purified by affinity chromatography, was cleaved first by hydroxylamine hydrochloride to release recombinant PG-1 and then by enterokinase to release PR-39. Purification of recombinant PR-39 and PG-1 was achieved. About 1.9 mg/l recombinant PR-39 and 1.1 mg/l PG-1 were obtained. The recombinant antimicrobial peptides showed antibacterial activities that were similar to those released from fusions of single peptides to GST.

Porcine host defense peptides: expanding repertoire and functions

Host defense peptides (HDPs) are a large group of innate immune effectors that are also termed antimicrobial peptides. Because of the rapid progress that has been made in completing several animal genomes, many HDPs have been systemically defined using bioinformatic analysis and partially characterized using reverse genomic approaches. In pigs, about 30 HDPs have been identified and partially characterized relative to structure and function. Antimicrobial activity of porcine HDPs has been extensively evaluated against a broad spectrum of microorganisms in vitro and evaluated for their protective role in vivo. Increasing evidence indicates that HDPs are functionally differentiated during posttranslational and postsecretory processing, and that the structural units for antimicrobial and immunoregulatory functions are separate. These findings suggest promising new avenues for therapeutic drug design based on HDPs, including porcine HDPs. This review summarizes and discusses advances in porcine HDPs research during the last decade with an emphasis on the rapidly expanding profiles and biological functions.

The cationic host defense peptide rCRAMP promotes gastric ulcer healing in rats

Cathelicidin, a cationic host defense peptide, has been shown to promote cutaneous wound repair and reaches high levels in the gastric mucosa during infection and inflammation. Therefore, we investigated whether this peptide contributes to gastric ulcer healing in rats. Ulcer induction increased the expression of rat cathelicidin rCRAMP in the gastric mucosa. Further increase in expression of rCRAMP by local injection of rCRAMP-encoding plasmid promoted ulcer healing by enhancing cell proliferation and angiogenesis. rCRAMP directly stimulated proliferation of cultured rat gastric epithelial cells (RGM-1), which was abolished by inhibitors of matrix metalloproteinase (MMP), epidermal growth factor receptors (EGFR) tyrosine kinase, or mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase. rCRAMP also increased EGFR and ERK1/2 phosphorylation via an MMP-dependent mechanism. Knockdown of transforming growth factor alpha (TGFalpha), which is a ligand of EGFR, by small interfering RNA completely nullified the mitogenic signals evoked by rCRAMP in RGM-1 cells. These findings suggest that rCRAMP exhibits prohealing activity in stomachs through TGFalpha-dependent transactivation of EGFR and its related signaling pathway to induce proliferation of gastric epithelial cells.

Expression of an additional cathelicidin antimicrobial peptide protects against bacterial skin infection

Cathelicidin antimicrobial peptides are effectors of innate immune defense in mammals. Humans and mice have only one cathelicidin gene, whereas domesticated mammals such as the pig, cow, and horse have multiple cathelicidin genes. We hypothesized that the evolution of multiple cathelicidin genes provides these animals with enhanced resistance to infection. To test this, we investigated the effects of the addition of cathelicidins by combining synthetic cathelicidin peptides in vitro, by producing human keratinocytes that overexpress cathelicidins in culture, or by producing transgenic mice that constitutively overexpress cathelicidins in vivo. The porcine cathelicidin peptide PR-39 acted additively with human cathelicidin LL-37 to kill group A Streptococcus (GAS). Lentiviral delivery of PR-39 enhanced killing of GAS by human keratinocytes. Finally, transgenic mice expressing PR-39 under the influence of a K14 promoter showed increased resistance to GAS skin infection (50% smaller necrotic ulcers and 60% fewer surviving bacteria). Similarly constructed transgenic mice designed to overexpress their native cathelicidin did not show increased resistance. These findings demonstrate that targeted gene transfer of a xenobiotic cathelicidin confers resistance against infection and suggests the benefit of duplication and divergence in the evolution of antimicrobial peptides.

Oxidized linoleic acid regulates expression and shedding of syndecan-4

Syndecan-4, a heparan sulfate proteoglycan that is widely expressed in the vascular wall and as a cell surface receptor, modulates events relevant to acute tissue repair, including cell migration and proliferation, cell-substrate interactions, and matrix remodeling. While syndecan-4 expression is regulated in response to acute vascular wall injury, its regulation under chronic proatherogenic conditions such as those characterized by prolonged exposure to oxidized lipids has not been defined. In this investigation, arterial smooth muscle cells were treated with 13-hydroperoxy-9,11-octadecadienoic acid (HPODE) and 13-hydroperoxy-10,12-octadecadienoic acid, oxidized products of linoleic acid, which is the major oxidizable fatty acid in LDL. Both oxidized fatty acids induced a dose-dependent, rapid upregulation of syndecan-4 mRNA expression that was not attenuated by cycloheximide. This response was inhibited by pretreatment with N-acetylcysteine, catalase, or MEK1/2 inhibitors, but not by curcumin or lactacystin, known inhibitors of NF-κB. These data suggest that oxidized linoleic acid induces syndecan-4 mRNA expression through the initial generation of intracellular hydrogen peroxide with subsequent activation of the extracellular signal-regulated kinase signaling pathway via MEK1/2. Notably, the HPODE-induced enhancement of syndecan-4 mRNA was accompanied by accelerated shedding of syndecan-4. In principle, alterations in both the cell surface expression and shedding of syndecan-4 may augment a variety of proatherogenic events that occur in response to oxidized lipids.