Human β‐defensin 3 affects the activity of pro‐inflammatory pathways associated with MyD88 and TRIF

Abstract

β-Defensins are cationic host defense peptides that form an amphipathic structure stabilized by three intramolecular disulfide bonds. They are key players in innate and adaptive immunity and have recently been shown to limit the production of pro-inflammatory cytokines in TLR4-stimulated macrophages. In the present study, we investigate the mechanism underlying the anti-inflammatory effect of human β-defensin 3 (hBD3). We show that the canonical structure of hBD3 is required for this immunosuppressive effect and that hBD3 rapidly associates with and enters macrophages. Examination of the global effect of hBD3 on transcription in TLR4-stimulated macrophages shows that hBD3 inhibits the transcription of pro-inflammatory genes. Among the altered genes there is significant enrichment of groups involved in the positive regulation of NF-κB including components of Toll-like receptor signaling pathways. We confirm these observations by showing corresponding decreases in protein levels of pro-inflammatory cytokines and cell surface molecules. In addition, we show that hBD3 reduces NF-κB signaling in cells transfected with MyD88 or TRIF and that hBD3 inhibits the TLR4 response in both MyD88- and TRIF-deficient macrophages. Taken together these findings suggest that the mechanism of hBD3 anti-inflammatory activity involves specific targeting of TLR signaling pathways resulting in transcriptional repression of pro-inflammatory genes.

Human β-defensin-3 promotes intestinal epithelial cell migration and reduces the development of necrotizing enterocolitis in a neonatal rat model

“…However, findings in knockout mice (matrilysin deficient) suggested that direct pathogen clearance was at least one mechanism of defensin function (25). Second, antimicrobial peptides, including hBD3, have been shown to demonstrate a biphasic effect, being proinflammatory at higher concentrations, but anti-inflammatory at lower levels (23,26,27). In contrast, our data showed hBD3 did not increase the expression of TNF-α in enterocytes.…”

Identification of a cell-penetrating peptide domain from human beta-defensin 3 and characterization of its anti-inflammatory activity

“…32 In previous studies, proinflammatory cytokines, such as TNF-α and IL-6, were completely blocked by hBD3 in pathogen-induced macrophages isolated from human bone marrow both in vitro and in vivo 33 through toll-like receptor-mediated signaling pathways and the subsequent transcriptional inhibition of inflammatory genes. 34 However, the therapeutic application of hBD3 has some limitations, including the difficulty of mass production due to its long amino acid sequence and the decreased stability observed at high ionic strength. Importantly, three disulfide bonds containing six cysteines maintain the stability of the hBD3 structure, as well as its anti-inflammatory properties.…”

The Novel Human β-Defensin 114 Regulates Lipopolysaccharide (LPS)-mediated Inflammation and Protects Sperm from Motility Loss

“…In addition to LPS binding, the direct interference of DEFB114 in inflammation signaling pathways in the presence of LPS could not be excluded. Among human DEFBs, DEFB103 associates with and rapidly enters macrophages and then inhibits both MyD88 and TRIF signaling pathways, resulting in the transcriptional repression of proinflammatory genes (38). Whether DEFB103 and DEFB114 utilize a similar mechanism to exert their anti-inflammatory activity is an interesting question.…”