Enhancement of phagocytosis by dynorphin A in mouse peritoneal macrophages

Dynorphin regulates the phagocytic activity of splenic phagocytes in wall lizards: involvement of a κ-opioid receptor-coupled adenylate-cyclase–cAMP–PKA pathway

“…In the wall lizard H. flaviviridis, dyn A (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) by acting through the -opioid receptor inhibited the phagocytosis of yeast cells by splenic phagocytes. This is in contrast to data reported in fish (Singh and Rai, 2010) and mammals (Ichinose et al, 1995), wherein, dyn A (1-17) stimulated the phagocytosis of yeast cells by fish splenic phagocytes (Singh and Rai, 2010) and latex particles by murine peritoneal macrophages (Ichinose et al, 1995). With respect to receptormediated action, dyn A (1-17) stimulated the phagocytosis through a -opioid receptor in fish only.…”

“…With respect to receptormediated action, dyn A (1-17) stimulated the phagocytosis through a -opioid receptor in fish only. Interestingly, in mammals, the stimulatory effect of dyn A (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) was mediated through a non-opioid receptor as the non-selective opioid receptor blocker naltrexone failed to block the effect of dyn A (1-17) on phagocytosis (Ichinose et al, 1995). Nevertheless, a specific opioid-receptor-mediated inhibitory effect of dynorphin(s) and its receptor agonist on phagocytosis has been reported in mammals.…”

“…In addition to an analgesic effect (Knoll and Carlezon, 2010), a role for dynorphins in the regulation of immune responses has emerged in recent years (Casellas et al, 1991;Ichinose et al, 1995;Singh and Rai, 2010). Furthermore, functional -, -and -opioid receptors belonging to the G-protein-coupled receptor (GPCR) superfamily (Law et al, 2000) have been demonstrated to be expressed by immune cells (Martin-Kleiner and Gabrilovac, 1997).…”

Identification of human cathelicidin peptide LL-37 as a ligand for macrophage integrin α_Mβ₂ (Mac-1, CD11b/CD18) that promotes phagocytosis by opsonizing bacteria

“…Indeed, screening of several proteins stored in neutrophil granules as well as mammalian cathelicidins and other cationic peptides showed that they bind the a M I-domain 20 (and unpublished data). Consistent with this proposal, we have recently shown that the cationic peptide dynorphin A that was previously shown to enhance phagocytosis 56 opsonizes bacteria and promotes phagocytosis through Mac-1. 57 Since negatively charged residues are generally strongly disfavored in the Mac-1 recognition motifs, it is tempting to speculate that the absence of negatively charged residues in some cathelicidin peptides (eg, bovine SMAP-29 and BMAP-27 1 ) as compared to LL-37 may increase their Mac-1-binding activity.…”

Inhibitory effects of dynorphin 3-14 on the lipopolysaccharide-induced toll-like receptor 4 signalling pathway

“…Furthermore, inhibition of LPS-induced NF-κB activation and subsequent IL-1β release following naloxone treatment in RAW264 cells was mediated by L-type calcium channels [16]. The enhancement of phagocytosis by DYN 1-17 in mouse peritoneal macrophages was reported to be dependent on intracellular calcium signalling [17], whereas in another study, the inhibition of LPS-induced production of nitric oxide and TNF-α by DYN 1-8 was not blocked by the KOR antagonist norbinaltorphimine (nor-BNI), indicative of the involvement of non-opioid mechanisms in these inhibitory effects [18].…”