Annexin A1 (AnxA1) is a protein that displays potent anti-inflammatory properties, but its expression in eye tissue and its role in ocular inflammatory diseases have not been well studied. We investigated the mechanism of action and potential uses of AnxA1 and its mimetic peptide (Ac2-26) in the endotoxin-induced uveitis (EIU) rodent model and in human ARPE-19 cells activated by LPS. In rats, analysis of untreated EIU after 24 and 48 h or EIU treated with topical applications or with a single s.c. injection of Ac2-26 revealed the anti-inflammatory actions of Ac2-26 on leukocyte infiltration and on the release of inflammatory mediators; the systemic administration of Boc2, a formylated peptide receptor (fpr) antagonist, abrogated the peptide’s protective effects. Moreover, AnxA1−/− mice exhibited exacerbated EIU compared with wild-type animals. Immunohistochemical studies of ocular tissue showed a specific AnxA1 posttranslational modification in EIU and indicated that the fpr2 receptor mediated the anti-inflammatory actions of AnxA1. In vitro studies confirmed the roles of AnxA1 and fpr2 and the protective effects of Ac2-26 on the release of chemical mediators in ARPE-19 cells. Molecular analysis of NF-κB translocation and IL-6, IL-8, and cyclooxygenase-2 gene expression indicated that the protective effects of AnxA1 occur independently of the NF-κB signaling pathway and possibly in a posttranscriptional manner. Together, our data highlight the role of AnxA1 in ocular inflammation, especially uveitis, and suggest the use of AnxA1 or its mimetic peptide Ac2-26 as a therapeutic approach.

ObjectivesTo establish the role and effect of glucocorticoids and the endogenous annexin A1 (AnxA1) pathway in inflammatory arthritis.MethodsAnkle joint mRNA and protein expression of AnxA1 and its receptors were analysed in naive and arthritic mice by real-time PCR and immunohistochemistry. Inflammatory arthritis was induced with the K/BxN arthritogenic serum in AnxA1+/+ and AnxA1−/− mice; in some experiments, animals were treated with dexamethasone (Dex) or with human recombinant AnxA1 or a protease-resistant mutant (termed SuperAnxA1). Readouts were arthritic score, disease incidence, paw oedema and histopathology, together with pro-inflammatory gene expression.ResultsAll elements of the AnxA1 pathway could be detected in naive joints, with augmentation during ongoing disease, due to the infiltration of immune cells. No difference in arthritis intensity of profile could be observed between AnxA1+/+ and AnxA1−/− mice. Treatment of mice with Dex (10 µg intraperitoneally daily from day 2) afforded potent antiarthritic effects highly attenuated in the knockouts: macroscopic changes were mirrored by histopathological findings and pro-inflammatory gene (eg, Nos2) expression. Presence of proteinase 3 mRNA in the arthritic joints led the authors to test AnxA1 and the mutant SuperAnxA1 (1 µg intraperitoneally daily in both cases from day 2), with the latter one being able to accelerate the resolving phase of the disease.ConclusionAnxA1 is an endogenous determinant for the therapeutic efficacy of Dex in inflammatory arthritis. Such an effect can be partially mimicked by application of SuperAnxA1 which may represent the starting point for novel antiarthritic therapeutic strategies.

The anti-inflammatory protein Annexin-A1 (ANXA1) is associated to tumor invasion process and its actions can be mediated by formylated peptides receptors (FPRs). Therefore, we evaluated the expression and correlation of ANXA1, FPR and cyclooxygenase-2 (COX-2) enzyme in esophageal and stomach inflammations and neoplasias. The study of proteins was performed by immunohistochemistry in biopsies of esophagitis, Barrett's esophagus, squamous cell carcinoma and adenocarcinoma of the esophagus, as well as gastritis, stomach polypus and gastric adenocarcinoma. The intensity of the expressions was evaluated by densitometry. The immunohistochemical and densitometric analyzes showed specificity for the FPR1 receptor and modulation of the ANXA1, COX-2 and FPR1 expressions in the epithelial cells in the different studied conditions. Increased immunoreactivity of these proteins was observed in cases of inflammation and stomach polypus. Interestingly, moderate immunoreactivity for ANXA1 and FPR1 but increased immunolabeling for COX-2 were observed in Barrett́s esophagus and esophageal adenocarcinomas. Also, there was reduced expression of ANXA1 and FPR1 in esophageal carcinoma but COX-2 overexpression in this tumor. There was no expression of FPR2 but ANXA1 and FPR1 expressions were positively correlated in all clinical conditions studied. Positive correlation between ANXA1 and COX-2 were also observed in inflammation conditions while negative correlation between ANXA1 and COX-2 was observed in esophageal carcinoma. Our results demonstrate the unregulated expression of ANXA1 and COX-2 in precursor lesions of esophageal and stomach cancers, reinforcing their involvement in gastroesophageal carcinogenesis. In addition, the data show that the actions of ANXA1 in the inflammatory and neoplastic processes of the esophagus and stomach are specifically mediated by the FPR1 receptor.

Mast cells (MCs) participate in all stages of skin healing and one of their mediators is the Annexin A1 protein (AnxA1), linked to inflammation, proliferation, migration and apoptosis processes, but not studied in thermal burns yet. Therefore, our objectives were to evaluate the behavior of MCs and AnxA1 in a second degree burn model, treated or not with silver sulfadiazine 1% (SDP 1%) and associated to macrophages quantification and cytokines dosages. MCs counts showed few cells in the early stages of repair but increased MCs in the final phases in the untreated group. The normal skin presented numerous tryptase-positive MCs that were reduced after burning in all analyzed periods. Differently, few chymase-positive MCs were observed in the early stages of healing, however, increased chymase-positive MCs were found at the final phase in the untreated group. MCs also showed high immunoreactivity for AnxA1 on day 3 in both groups. In the tissue there was a strong protein expression in the early stages of healing, but in the final phases only in the SDP treated animals. TNF-α, IL-1β, IL-6, IL-10 and MCP-1 levels and macrophages quantification were increased in inflammation and reepithelialization phases. Reduced IL-1β, IL-6 and IL-10 levels and numerous macrophages occurred in the treated animals during tissue repair. Our results indicate modulation in the profile of MCs and AnxA1expression during healing by the treatment with SDP 1%, pointing them as targets for therapeutic interventions on skin burns.