ANXA1Ac2–26 peptide, a possible therapeutic approach in inflammatory ocular diseases

Annexin A1 in the nervous and ocular systems

The therapeutic potential of Annexin A1, an important member of the Annexin superfamily, has become evident in results of experiments with multiple human systems and animal models. The anti-inflammatory and pro-resolving effects of Annexin A1 are characteristic of pathologies involving the nervous system. In this review, we initially describe the expression sites of Annexin A1, then outline the mechanisms by which Annexin A1 maintains the neurological homeostasis through either formyl peptide receptor 2 or other molecular approaches; and, finally, we discuss the neuroregenerative potential qualities of Annexin A1. The eye and the nervous system are anatomically and functionally connected, but the association between visual system pathogenesis, especially in the retina, and Annexin A1 alterations has not been well summarized. Therefore, we explain the beneficial effects of Annexin A1 for ocular diseases, especially for retinal diseases and glaucoma on the basis of published findings, and we explore present and future delivery strategies for Annexin A1 to the retina.

Effects of hyperosmolarity on annexin A1 on ocular surface epithelium in vitro

Osmotic stress is an important challenge to cell function. Dry eye pathology is characterized by elevated tear film osmolarity as consequence of decreased tear secretion and/or increased evaporation. Dry eye pathogenesis is not completely clarified. However, it is known that tear hyperosmolarity induces NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain-cointaining 3) inflammasome activation and inflammatory mediators release that leads to ocular surface damage. Annexin A1 is a protein involved in anti-inflammatory or pro-resolution actions in different tissues while its presence and biological role on ocular surface has been scarcely examined. In this study, potential changes in annexin A1 protein expression and secretion on the ocular surface after exposure to hyperosmolar conditions were evaluated. In addition, considering the significant role of inflammation in dry eye pathology, the potential anti-inflammatory activity of Ac2-26, an annexin A1 peptide mimicking its N-terminus, was assessed. Cytosolic and membrane staining was detected for annexin A1 in corneal and conjunctival epithelial cells. A native form of annexin A1 together with a truncated form were detected by western blot analysis. Under hyperosmotic conditions increased protein levels of intracellular and secreted annexin A1 as well as higher expression of its receptor Fpr2 (formyl peptide receptor type 2) were found. Treatment with mimetic peptide Ac2-26 ameliorated NLRP3 activation and interleukin 1β (IL-1β) release triggered by elevated osmolarity in corneal and conjunctival epithelial cells. These findings suggest a potential role of annexin A1 and its mimetic peptide modulating key inflammatory events associated to dry eye.

Annexin A1 Mimetic Peptide and Piperlongumine: Anti-Inflammatory Profiles in Endotoxin-Induced Uveitis

Uveitis is one of the main causes of blindness worldwide, and therapeutic alternatives are worthy of study. We investigated the effects of piperlongumine (PL) and/or annexin A1 (AnxA1) mimetic peptide Ac2-26 on endotoxin-induced uveitis (EIU). Rats were inoculated with lipopolysaccharide (LPS) and intraperitoneally treated with Ac2-26 (200 µg), PL (200 and 400 µg), or Ac2-26 + PL after 15 min. Then, 24 h after LPS inoculation, leukocytes in aqueous humor, mononuclear cells, AnxA1, formyl peptide receptor (fpr)1, fpr2, and cyclooxygenase (COX)-2 were evaluated in the ocular tissues, along with inflammatory mediators in the blood and macerated supernatant. Decreased leukocyte influx, levels of inflammatory mediators, and COX-2 expression confirmed the anti-inflammatory actions of the peptide and pointed to the protective effects of PL at higher dosage. However, when PL and Ac2-26 were administered in combination, the inflammatory potential was lost. AnxA1 expression was elevated among groups treated with PL or Ac2-26 + PL but reduced after treatment with Ac2-26. Fpr2 expression was increased only in untreated EIU and Ac2-26 groups. The interaction between Ac2-26 and PL negatively affected the anti-inflammatory action of Ac2-26 or PL. We emphasize that the anti-inflammatory effects of PL can be used as a therapeutic strategy to protect against uveitis.

Drops of Lactiplantibacillus plantarum CRL 759 culture supernatant attenuates eyes inflammation induced by lipopolysaccharide

Anti-inflammatory effect of soluble secreted compounds of probiotic bacteria was widely demonstrated as therapy for different inflammatory diseases, but was not investigated in inflammatory eye disorders. The aim of this study was to determine whether Lactiplantibacillus plantarum CRL759 cell-free supernatant reduced inflammatory parameters and clinical signs in ocular inflammations. First, we evaluated the effect of L. plantarum CRL759 supernatant in vitro on human retinal cell line, ARPE-19 cells, stimulated with lipopolysaccharide (LPS). Then, we investigated in vivo its capacity to decrease inflammation by local administration on the eyes of mice with endotoxin induced inflammation. In vitro assays demonstrated that L. plantarum CRL759 supernatant reduced the production of interleukin (IL)-6, IL-8, nitric oxide and thiobarbituric acid reactive substances in LPS-stimulated ARPE-19 cells. Our in vivo data proved that L. plantarum supernatant significantly reduced the clinical score of endotoxin treated mice and diminished levels of tumour necrosis factor alpha, interferon gamma and protein concentration in aqueous humour. Histological examination showed reduction of infiltrating inflammatory cells in the posterior segment of the eyes. As far as we know, this is the first report showing that Lactobacillus spp. supernatant administered as drops reduces some parameters of ocular inflammation. This promising strategy is safe and could alleviate symptoms and signs of ocular inflammation in people that are refractories to the conventional therapies.

Genome-Wide Association Analysis Identified ANXA1 Associated with Shoulder Impingement Syndrome in UK Biobank Samples

Shoulder impingement syndrome (SIS) is a common shoulder disorder with unclear genetic mechanism. In this study, Genome-wide Association Study (GWAS) was conducted to identify the candidate loci associated with SIS by using the UK Biobank samples (including 3,626 SIS patients and 3,626 control subjects). Based on the GWAS results, gene set enrichment analysis was further performed to detect the candidate gene ontology and pathways associated with SIS. We identified multiple risk loci associated with SIS, such as rs750968 (P = 4.82 × 10⁻⁸), rs754832 (P = 4.83 × 10⁻⁸) and rs1873119 (P = 6.39 × 10⁻⁸) of ANXA1 gene. Some candidate pathways have been identified related to SIS, including those linked to infection response and hypoxia, “ZHOU_INFLAMMATORY_RESPONSE_FIMA_DN” (P = 0.012) and “MANALO_HYPOXIA_UP” (P = 5.00 × 10⁻⁵). Our results provide novel clues for understanding the genetic mechanism of SIS.

Molecular cloning, characterization and expression profiles of Annexin family (ANXA1~A6) in yellow catfish (Pelteobagrus fulvidraco) and ANX regulation by CpG ODN responding to bacterial infection

Up to now, many previous reports have emphasized that Annexins (ANX) family played an important role in immune responses. Aeromonas hydrophila (A. hydrophila), the most common zoonotic pathogenic bacteria of yellow catfish (Pelteobagrus fulvidraco), can cause serious economic loss, especially to yellow catfish with high economic value. In our previous work, we demonstrated that synthetic oligodeoxynucleotides containing CpG motifs (CpG ODN) owned powerful immunostimulatory activity. However, the relationship among Pelteobagrus fulvidraco Annexins (Pf_ANX), CpG ODN and A. hydrophila is unknown. Therefore, we cloned Pf_ANX1-6 genes and analyzed its sequences, structures, genetic evolution, post-translation modifications (PTMs), Ca²⁺ ion binding sites and tissue distribution to reveal the relevance. In addition, we investigated the responses of ANXA1-6 and cytokines in intestine and spleen as well as morbidity/survival rate of fish post CpG ODN immunization and/or A. hydrophila infection. The results showed that compared with challenge alone (challenge-CK) group, the CpG immunization following challenge (CpG-challenge) group displayed relatively flat IL-1β level throughout in both organs. Meanwhile, the expression of IFN-γ and morbidity/survival rate of fish in CpG-challenge group showed a great improvement compared with the challenge-CK group. Our results indicated that CpG ODN could improve morbidity/survival by up-regulating Pf_ANXA 1, 2 and 5 in the intestine and spleen to ameliorate inflammatory responses and promote anti-infective responses. Our findings offer some important insights into ANX related to the immunity of fish infection and lay a theoretical basis for the prevention and treatment of fish infections.

Annexin A1 peptide and endothelial cell-conditioned medium modulate cervical tumorigenesis

Cervical cancer is one of the leading causes of cancer death in women worldwide, and its tumorigenesis can be influenced by the microenvironment. The anti-inflammatory protein annexin A1 (ANXA1) has been reported to be associated with cancer progression and metastasis, suggesting that it plays a role in regulating tumour cell proliferation. Here, we examined the effect of the N-terminal peptide Ac2-26 of ANXA1 on the HaCaT cell line (normal) and HeLa cell line (cervical cancer) co-cultured with endothelium cell-conditioned medium (HMC). Treatment with Ac2-26 decreased proliferation and increased motility of cervical cancer cells, but did not affect cellular morphology or viability. Combined HMC stimulus and Ac2-26 treatment resulted in an increase in apoptotic HeLa cells, upregulated expression of MMP2, and downregulated expression of COX2,EP3 and EP4. In conclusion, Ac2-26 treatment may modulate cellular and molecular mechanisms underlying cervical carcinogenesis.

Silencing of Annexin A1 suppressed the apoptosis and inflammatory response of preeclampsia rat trophoblasts

Preeclampsia (PE) is a disorder that is characterized by pregnancy-induced hypertension. It has been reported that Annexin A1 (ANXA1) is highly expressed in the plasma of women diagnosed with PE. Therefore, the present study aimed to examine the effect of ANXA1 on PE rats. The PE animal model was constructed in rats using Nω-nitro-L-arginine methyl ester (L-NAME), and the blood pressure and urine protein levels of rats were detected. The pathological features of placental tissue, and the levels of inflammatory factors and ANXA1 were respectively measured by hematoxylin-eosin staining, enzyme-linked immunosorbent assay and immunohistochemical assay. The activity of trophoblasts obtained from PE placental tissue was measured using immunofluorescence staining, while cell apoptosis was assessed using flow cytometry. The levels of associated factors were determined by reverse transcription-quantitative polymerase chain reaction and western blot analysis. The results identified that systolic blood pressure, diastolic blood pressure, mean arterial pressure and urine protein levels were enhanced, and that the contents of ANXA1, tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6 and IL-8 were increased in the L-NAME group. Transfection with small interfering RNA (siRNA)-ANXA1 markedly decreased the apoptosis and inflammatory response of trophoblasts. In addition, siRNA-ANXA1 upregulated the levels of B-cell lymphoma-2 (Bcl-2) and pro-caspase-3, and downregulated the levels of Bcl-2-associated X protein, cleaved-caspase-3, TNF-α, IL-1β, IL-6 and IL-8. Furthermore, siRNA-ANXA1 repressed the phosphorylation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3); however, siRNA-ANXA1 did not alter the levels of JAK2 and STAT3. Therefore, silencing of ANXA1 suppressed the apoptosis and inflammatory response of PE rat trophoblasts, and downregulated JAK2/STAK3 pathway.

Annexin A12-26 Treatment Improves Skin Heterologous Transplantation by Modulating Inflammation and Angiogenesis Processes

Skin graft successful depends on reduction of local inflammation evoked by the surgical lesion and efficient neovascularization to nutrition the graft. It has been shown that N-terminal portion of the Annexin A1 protein (AnxA1) with its anti-inflammatory properties induces epithelial mucosa repair and presents potential therapeutic approaches. The role of AnxA1 on wound healing has not been explored and we investigated in this study the effect of the peptide Ac2-26 (N-terminal AnxA1 peptide Ac2-26; AnxA1_2-26) on heterologous skin scaffolds transplantation in BALB/c mice, focusing on inflammation and angiogenesis. Treatment with AnxA1_2-26, once a day, from day 3-60 after scaffold implantation improved the take of the implant, induced vessels formation, enhanced gene and protein levels of the vascular growth factor-A (VEGF-A) and fibroblast influx into allograft tissue. It also decreased pro- while increasing anti-inflammatory cytokines. The pro-angiogenic activity of AnxA1_2-26 was corroborated by topical application of AnxA1_2-26 on the subcutaneous tissue of mice. Moreover, treatment of human umbilical endothelial cells (HUVECs) with AnxA1_2-26 improved proliferation, shortened cycle, increased migration and actin polymerization similarly to those evoked by VEGF-A. The peptide treatment instead only potentiated the tube formation induced by VEGF-A. Collectively, our data showed that AnxA1_2-26 treatment favors the tissue regeneration after skin grafting by avoiding exacerbated inflammation and improving the angiogenesis process.