Annexin A1 mimetic peptide controls the inflammatory and fibrotic effects of silica particles in mice.

BACKGROUND AND PURPOSE: Endogenous glucocorticoids are pro-resolving mediators, an example of which is the endogenous glucocorticoid-regulated protein annexin A1 (ANXA1). Because silicosis is an occupational lung disease characterized by unabated inflammation and fibrosis, in this study we tested the therapeutic properties of the N-terminal ANXA1-derived peptide annexin 1-(2-26) (Ac2-26) on experimental silicosis. EXPERIMENTAL APPROACH: Swiss-Webster mice were administered silica particles intranasally and were subsequently treated with intranasal peptide Ac2-26 (200 µg per mouse) or dexamethasone (25 µg per mouse) for 7 days, starting 6 h post-challenge. Ac2-26 abolished the leukocyte infiltration, collagen deposition, granuloma formation and generation of pro-inflammatory cytokines evoked by silica; these variables were only partially inhibited by dexamethasone. KEY RESULTS: A clear exacerbation of the silica-induced pathological changes was observed in ANXA1 knockout mice as compared with their wild-type (WT) littermate controls. Incubation of lung fibroblasts from WT mice with Ac2-26 in vitro reduced IL-13 or TGF-ß-induced production of CCL2 (MCP-1) and collagen, but this peptide did not affect the production of CCL2 (MCP-1) by stimulated fibroblasts from formyl peptide receptor type 1 (FPR1) knockout mice. Ac2-26 also inhibited the production of CCL2 (MCP-1) from fibroblasts of FPR2 knockout mice. CONCLUSIONS AND IMPLICATIONS: Collectively, our findings reveal novel protective properties of the ANXA1 derived peptide Ac2-26 on the inflammatory and fibrotic responses induced by silica, and suggest that ANXA1 mimetic agents might be a promising strategy as innovative anti-fibrotic approaches for the treatment of silicosis.

Annexin-A1 gene expression during liver development and post-translation modification after experimental endotoxemia.

OBJECTIVE AND DESIGN: We have previously reported a role for annexin-A1 in liver proliferation and tumorogenicity as well as its action as an acute phase protein in a model of endotoxemia in interleukin-6 null mice. MATERIAL AND METHODS: In this study, we have investigated the analysis of the gene and protein expression in annexin-A1 null mice and the wild type livers during foetal and adult life, and in the presence of a proinflammatory stimulus. RESULTS: The data indicate a link between the expression of the annexin-A1 as serine-phosphorylated-protein during early events of the inflammatory response and as tyrosine-phosphorylated-form at later time-points, during the resolution of inflammation. CONCLUSIONS: The study of annexin-A1 post-translation modification may promote a new annexin-A1 peptide discovery programme to treat specific pathologies.

An immunocytochemical and in situ hybridization analysis of annexin 1 expression in rat mast cells: modulation by inflammation and dexamethasone.

The presence and localization of the anti-inflammatory protein annexin 1 (also known as lipocortin 1) in perivenular rat mast cells was investigated here. Using the rat mesenteric microvascular bed and a combination of morphologic techniques ranging from immunofluorescence to electron microscopy analyses, we detected the presence of annexin 1 in discrete intracellular sites, both in the nucleus and in the cytoplasm. In resting mast cells, most of the protein pool (approximately 80% of the cytosolic portion) was localized to cytoplasmic granules. In agreement with other cell types, treatment of rats with dexamethasone (0.2 mg/kg, ip) increased annexin 1 expression in mast cells, inducing a remarkable appearance of clusters of protein immunoreactivity. This effect was most likely the result of de novo protein synthesis as determined by an increase in mRNA seen by in situ hybridization. Triggering an ongoing experimental inflammatory response (0.3 mg of carrageenin, ip) increased annexin 1 mRNA and protein levels. In conclusion, we report for the first time the localization of annexin 1 in connective tissue mast cells, and its susceptibility not only to glucocorticoid hormone treatment, but also to an experimental acute inflammatory response.

Role of lipocortin-1 in the anti-hyperalgesic actions of dexamethasone.

1. The effect of dexamethasone, lipocorton-1(2-26) and an antiserum to lipocortin-1(2-26) (LCPS1) upon the hyperalgesic activities in rats of carrageenin, bradykinin, tumour necrosis factor alpha (TNF alpha), interleukin-1(2), interleukin-6 (IL-6), interleukin-8 (IL-8), prostaglandin E beta (PGE2) and dopamine were investigated in a model of mechanical hyperalgesia. 2. Hyperalgesic responses to intraplantar (i.pl.) injections of carrageenin (100 micrograms), bradykinin (500 ng), TNF alpha (2.5 pg), IL-1 beta (0.5 pg), and IL-6 (1.0 ng), but not responses to IL-8 (0.1 ng), PGE2 (100 ng) and dopamine (10 micrograms), were inhibited by pretreatment with dexamethasone (0.5 mg kg-1, subcutaneously, s.c., or 0.04-5.0 micrograms/paw). 3. Inhibition of hyperalgesic responses to injections (i.pl.) of bradykinin (500 ng) and IL-1 beta (0.5 pg) by dexamethasone (0.5 mg kg-1, s.c.) was reversed by LCPS1 (0.5 ml kg-1, injected s.c., 24 h and 1 h before hyperalgesic substances) and hyperalgesic responses to injections (i.pl.) of bradykinin (500 ng), TNF alpha (2.5 pg) and IL-1 beta (0.5 pg), but not responses to PGE2 (100 ng), were inhibited by pretreatment with lipocortin-1(2-26) (100 micrograms/paw). Also, lipocortin-1(2-26) (30 and 100 micrograms ml-1 and dexamethasone (10 micrograms ml-1) inhibited TNF alpha release by cells of the J774 (murine macrophage-like) cell-line stimulated with LPS (3 micrograms ml-1), and LCPS1 partially reversed the inhibition by dexamethasone. These data are consistent with an important role for endogenous lipocortin-1(2-26) in mediating the anti-hyperalgesic effect of dexamethasone, with inhibiton of TNF alpha production by lipocortin-1(2-26) contributing, in part, to this role. 4. Although arachidonic acid by itself was not hyperalgesic, the hyperalgesic response to IL-1 beta (0.25 pg, i.pl.) was potentiated by arachidonic acid (50 micrograms) and the potentiated response was inhibited by dexamethasone (50 micrograms, i.pl.) and lipocortin-1(2-26) (100 micrograms, i.pl.). Also, lipocortin-1(2-26) (30 and 100 micrograms ml-1) inhibited/abolished PGE2 release by J774 cells stimulated with LPS (3 micrograms ml-1). These data suggest that, in inflammatory hyperalgesia, inhibition of the induction of cyclo-oxygenase 2 (COX-2), rather than phospholipase A2, by dexamethasone and lipocortin-1(2-26) accounts for the anti-hyperalgesic effects of these agents. 5. The above data support the notion that induction of lipocortin by dexamethasone plays a major role in the inhibition by dexamethasone of inflammatory hyperalgesia evoked by carrageenin, bradykinin and the cytokines TNF alpha, IL-1 beta and IL-6, and provides additional evidence that the biological activity of lipocortin resides within the peptide lipocortin-1(2-26). Further, the data suggest that inhibition of lipocortin-1(2-26) of eicosanoid production by COX-2 also contributes to the anti-hyperalgesic effect of lipocortin-1.