An antimicrobial peptide with angiogenic properties, AG-30/5C, activates human mast cells through the MAPK and NF-κB pathways

Abstract

Apart from their direct antimicrobial activities against invading pathogens, antimicrobial peptides exhibit additional protective functions that have led to their being named host defense peptides (HDPs). These functions include the stimulation of the production of cytokines/chemokines, the promotion of chemotaxis and cell proliferation and the induction of angiogenesis and wound healing. AG-30/5C is a novel angiogenic HDP that in addition to its antimicrobial activity also activates fibroblasts and endothelial cells and promotes angiogenesis and wound healing. Given that mast cells are found primarily in the vicinity of vessels, where they are intimately involved in wound healing, we hypothesized that AG-30/5C may activate mast cells. We demonstrated that AG-30/5C activated LAD2 human mast cells to degranulate and produce lipid mediators including leukotriene C4, prostaglandin D2 and E2. Moreover, AG-30/5C increased mast cell chemotaxis and induced the production of the cytokines GM-CSF and TNF-α and various chemokines, such as IL-8, MCP-1, MCP-3, MIP-1α and MIP-1β. The chemotaxis and cytokine/chemokine production induced by AG-30/5C were suppressed by both pertussis toxin and U-73122, suggesting the involvement of the G protein and phospholipase C pathways in AG-30/5C-induced mast cell activation. Furthermore, these pathways were activated downstream of the MAPK and NF-κB signaling molecules, as demonstrated by the inhibitory effects of ERK-, JNK-, p38- and NF-κB-specific inhibitors on cytokine/chemokine production. Interestingly, AG-30/5C caused the phosphorylation of MAPKs and IκB. We suggest that the angiogenic and antimicrobial peptide AG-30/5C plays a key role in the recruitment and activation of human mast cells at inflammation and wound sites.

Immunomodulatory effects of anti-microbial peptides

“…Likewise, the in vivo anti-bacterial effects of the designer Chex-Arg20 proline-arginine-rich peptide are more extensive when embedded in a nanofiber formulation than after intramuscular administration using only one-tenth of the active pharmaceutical ingredient [49]. The various cutaneous and wound healing activities are likely linked to the ability of HDP to activate mast cells and enhance the production of cytokines (GM-CSF, TNF-α) and chemokines (IL-8-MCPs and MIPs) at inflammation and injury sites [50]. Along these lines, a polyelectrolyte multilayer film based on polyarginine and hyaluronic acid has a remarkable anti-microbial activity in a film format against Staphylococcus aureus and as well as inhibits the production of inflammatory cytokines released by human primary macrophages [51].…”

Angiogenic Host Defense Peptide AG-30/5C and Bradykinin B2 Receptor Antagonist Icatibant Are G Protein Biased Agonists for MRGPRX2 in Mast Cells

“…AG-30/5C is a synthetic angiogenic HDP that promotes new blood vessel formation, induces human keratinocyte proliferation, effectively clears microbial infection, and induces wound healing in mice (17). The ability of AG-30/5C to harness MC's immunomodulatory property likely contributes to its host defense, but the mechanism via which it activates MC remains unknown (19). The data presented in this article clearly demonstrate that AG-30/ 5C induces MC degranulation via MRGPRX2.…”

“…We previously showed that PTx inhibits MC degranulation in response to HDP human b-defensin 3 without affecting Ca 2+ mobilization (19). We therefore tested the effect of PTx on degranulation and Ca 2+ mobilization to the well-established MRGPRX2 agonists compound 48/80 and AG-30/5C.…”

“…Interestingly, topical application of AG-30/5C on a mouse diabetic wound-healing model infected with methicillinresistant Staphylococcus aureus results in clearance of the microbe and promotes accelerated wound healing (17). This in vivo effect of AG-30/5C likely reflects its ability to kill microbes directly, to harness MC's immunomodulatory property, to promote angiogenesis, and to induce keratinocyte migration and proliferation (17)(18)(19). Although AG-30/5C induces mediator release in human MC via signaling pathways involving G protein and phospholipase C, the possibility that it does so via a cell surface GPCR has not been determined (19).…”

Lentinan Administration Alleviates Diarrhea of Rotavirus-Infected Weaned Pigs via Regulating Intestinal Immunity

“…Host defense peptides (HDPs) also are an important part of innate immunity, which are the barriers for preventing invasion of pathogens [44]. This process is derived from HDPs regulating in ammatory cytokines and responses via some signaling pathways, such as Toll-like receptors 4, mitogen-activated protein kinase and nuclear factor-kappa B signaling pathways [45][46][47][48]. And the HBD-2 mRNA expression in pulmonary epithelial cells could be induced by lentinan in a concentration-and time-dependent manner [49].…”