ANXA1 Promotes Tumor Immune Evasion by Binding PARP1 and Upregulating Stat3-Induced Expression of PD-L1 in Multiple Cancers.

The deregulation of Annexin A1 (ANXA1), a regulator of inflammation and immunity, leads to cancer growth and metastasis. However, whether ANXA1 is involved in cancer immunosuppression is still unclear. Here, we report that ANXA1 knockdown (i) dramatically downregulates programmed cell death-ligand 1 (PD-L1) expression in breast cancer, lung cancer, and melanoma cells; (ii) promotes T cell-mediated killing of cancer cells in vitro; and (iii) inhibits cancer immune escape in immune-competent mice via downregulating PD-L1 expression and increasing the number and killing activity of CD8+ T cells. Mechanistically, ANXA1 functioned as a sponge molecule for interaction of PARP1 and Stat3. Specifically, binding of ANXA1 to PARP1 decreased PARP1's binding to Stat3, which reduced poly(ADP-ribosyl)ation and dephosphorylation of Stat3 and thus, increased Stat3's transcriptional activity, leading to transcriptionally upregulated expression of PD-L1 in multiple cancer cells. In clinical samples, expression of ANXA1 and PD-L1 was significantly higher in breast cancer, non-small cell lung cancer, and skin cutaneous melanoma compared with corresponding normal tissues and positively correlated in cancer tissues. Moreover, using both ANXA1 and PD-L1 proteins for predicting efficacy of anti-PD-1 immunotherapy and patient prognosis was superior to using individual proteins. Our data suggest that ANXA1 promotes cancer immune escape via binding PARP1 and upregulating Stat3-induced expression of PD-L1, that ANXA1 is a potential new target for cancer immunotherapy, and combination of ANXA1 and PD-L1 expression is a potential marker for predicting efficacy of anti-PD-1 immunotherapy in multiple cancers.

Annexin A1 (Ac2-26)-dependent Fpr2 receptor alleviates sepsis-induced acute kidney injury by inhibiting inflammation and apoptosis in vivo and in vitro.

OBJECTIVES: Excessive inflammatory responses and apoptosis are critical pathologies that contribute to sepsis-induced acute kidney injury (SI-AKI). Annexin A1 (ANXA1), a member of the calcium-dependent phospholipid-binding protein family, protects against SI-AKI through its anti-inflammatory and antiapoptotic effects, but the underlying mechanisms are still largely unknown. METHODS: In vivo, SI-AKI mouse models were established via caecal ligation and puncture (CLP) and were then treated with the Ac2-26 peptide of ANXA1 (ANXA1 (Ac2-26)), WRW4 (Fpr2 antagonist) or both. In vitro, HK-2 cells were induced by lipopolysaccharide (LPS) and then treated with ANXA1 (Ac2-26), Fpr2-siRNA or both. RESULTS: In the present study, we found that the expression levels of ANXA1 were decreased, and the expression levels of TNF-α, IL-1ß, IL-6, cleaved caspase-3, cleaved caspase-8 and Bax were significantly increased, accompanied by marked kidney tissue apoptosis in vivo. Moreover, we observed that ANXA1 (Ac2-26) significantly reduced the levels of TNF-α, IL-1ß and IL-6 and cleaved caspase-3, cleaved caspase-8, FADD and Bax and inhibited apoptosis in kidney tissue and HK-2 cells, accompanied by pathological damage to kidney tissue. Seven-day survival, kidney function and cell viability were significantly improved in vivo and in vitro, respectively. Furthermore, the administration of ANXA1 (Ac2-26) inhibited the CLP- or LPS-induced phosphorylation of PI3K and AKT and downregulated the level of NF-κB in vivo and in vitro. Moreover, our data demonstrate that blocking the Fpr2 receptor by the administration of WRW4 or Fpr2-siRNA reversed the abovementioned regulatory role of ANXA1, accompanied by enhanced phosphorylation of PI3K and AKT and upregulation of the level of NF-κB in vivo and in vitro. CONCLUSIONS: Taken together, this study provides evidence that the protective effect of ANXA1 (Ac2-26) on SI-AKI largely depends on the negative regulation of inflammation and apoptosis via the Fpr2 receptor.

Resolution Pharmacology: Focus on Pro-Resolving Annexin A1 and Lipid Mediators for Therapeutic Innovation in Inflammation.

Chronic diseases that affect our society are made more complex by comorbidities and are poorly managed by the current pharmacology. While all present inflammatory etiopathogeneses, there is an unmet need for better clinical management of these diseases and their multiple symptoms. We discuss here an innovative approach based on the biology of the resolution of inflammation. Studying endogenous pro-resolving peptide and lipid mediators, how they are formed, and which target they interact with, can offer innovative options through augmenting the expression or function of pro-resolving pathways or mimicking their actions with novel targeted molecules. In all cases, resolution offers innovation for the treatment of the primary cause of a given disease and/or for the management of its comorbidities, ultimately improving patient quality of life. By implementing resolution pharmacology, we harness the whole physiology of inflammation, with the potential to bring a marked change in the management of inflammatory conditions.

Pro-resolving therapies as potential adjunct treatment for infectious diseases: Evidence from studies with annexin A1 and angiotensin-(1-7).

Infectious diseases, once believed to be an eradicable public health threat, still represent a leading cause of death worldwide. Environmental and social changes continuously favor the emergence of new pathogens and rapid dissemination around the world. The limited availability of anti-viral therapies and increased antibiotic resistance has made the therapeutic management of infectious disease a major challenge. Inflammation is a primordial defense to protect the host against invading microorganisms. However, dysfunctional inflammatory responses contribute to disease severity and mortality during infections. In recent years, a few studies have examined the relevance of resolution of inflammation in the context of infections. Inflammation resolution is an active integrated process transduced by several pro-resolving mediators, including Annexin A1 and Angiotensin-(1-7). Here, we examine some of the cellular and molecular circuits triggered by pro-resolving molecules and that may be beneficial in the context of infectious diseases.

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.

Decreased Annexin A1 expression enhances sensitivity to docetaxel, cisplatin and 5-fluorouracil combination induction chemotherapy in oral squamous cell carcinoma.

BACKGROUND: Annexin A1, a member of the Annexin superfamily, has been shown to play a vital role in a broad range of molecular and cellular processes. This study aims to explore the relationship between the Annexin A1 expression and the clinical response to cisplatin, docetaxel and 5-fluorouracil (TPF) as induction chemotherapy in patients with oral squamous cell carcinoma (OSCC). METHODS: This study recruited two hundred thirty-two patients from a III/IVA OSCC trial. Immunohistochemistry was used to assess the level of Annexin A1 expression. Overexpression and knockdown methods in HB96, HN4 and CAL27 cell lines were used to assess the role of Annexin A1 in the neoplastic cellular response to chemotherapy. RESULTS: We found that reduced expression of Annexin A1 conferred a prognostic benefit from induction chemotherapy based on the TPF drug combination in patients with moderately/poorly differentiated disease. Using an in vitro model, we found that low Annexin A1 enhanced cellular proliferation by activating the EGFR/AKT signalling pathway and inhibiting p27 expression. Furthermore, low Annexin A1 initiated a significant decrease in cell viability after treatment with TPF agents. In addition, downregulation of Annexin A1 promoted apoptosis induced by docetaxel, cisplatin and 5-fluorouracil, and upregulation of Annexin A1 inhibited apoptosis. CONCLUSION: Annexin A1 may be of prognostic value in patients with locally advanced OSCC who are managed with TPF chemotherapy, as low Annexin A1 promotes chemosensitivity to TPF chemotherapy in oral cancer cells via enhanced caspase-dependent apoptosis.

Annexin A1 protects against cerebral ischemia-reperfusion injury by modulating microglia/macrophage polarization via FPR2/ALX-dependent AMPK-mTOR pathway.

BACKGROUND: Cerebral ischemia-reperfusion (I/R) injury is a major cause of early complications and unfavorable outcomes after endovascular thrombectomy (EVT) therapy in patients with acute ischemic stroke (AIS). Recent studies indicate that modulating microglia/macrophage polarization and subsequent inflammatory response may be a potential adjunct therapy to recanalization. Annexin A1 (ANXA1) exerts potent anti-inflammatory and pro-resolving properties in models of cerebral I/R injury. However, whether ANXA1 modulates post-I/R-induced microglia/macrophage polarization has not yet been fully elucidated. METHODS: We retrospectively collected blood samples from AIS patients who underwent successful recanalization by EVT and analyzed ANXA1 levels longitudinally before and after EVT and correlation between ANXA1 levels and 3-month clinical outcomes. We also established a C57BL/6J mouse model of transient middle cerebral artery occlusion/reperfusion (tMCAO/R) and an in vitro model of oxygen-glucose deprivation and reoxygenation (OGD/R) in BV2 microglia and HT22 neurons to explore the role of Ac2-26, a pharmacophore N-terminal peptide of ANXA1, in regulating the I/R-induced microglia/macrophage activation and polarization. RESULTS: The baseline levels of ANXA1 pre-EVT were significantly lower in 23 AIS patients, as compared with those of healthy controls. They were significantly increased to the levels found in controls 2-3 days post-EVT. The increased post-EVT levels of ANXA1 were positively correlated with 3-month clinical outcomes. In the mouse model, we then found that Ac2-26 administered at the start of reperfusion shifted microglia/macrophage polarization toward anti-inflammatory M2-phenotype in ischemic penumbra, thus alleviating blood-brain barrier leakage and neuronal apoptosis and improving outcomes at 3 days post-tMCAO/R. The protection was abrogated when mice received Ac2-26 together with WRW4, which is a specific antagonist of formyl peptide receptor type 2/lipoxin A4 receptor (FPR2/ALX). Furthermore, the interaction between Ac2-26 and FPR2/ALX receptor activated the 5' adenosine monophosphate-activated protein kinase (AMPK) and inhibited the downstream mammalian target of rapamycin (mTOR). These in vivo findings were validated through in vitro experiments. CONCLUSIONS: Ac2-26 modulates microglial/macrophage polarization and alleviates subsequent cerebral inflammation by regulating the FPR2/ALX-dependent AMPK-mTOR pathway. It may be investigated as an adjunct strategy for clinical prevention and treatment of cerebral I/R injury after recanalization. Plasma ANXA1 may be a potential biomarker for outcomes of AIS patients receiving EVT.

The formyl peptide receptor agonist Ac2-26 alleviates neuroinflammation in a mouse model of pneumococcal meningitis.

BACKGROUND: Bacterial meningitis is still a cause of severe neurological disability. The brain is protected from penetrating pathogens by the blood-brain barrier and the innate immune system. The invading pathogens are recognized by pattern recognition receptors including the G-protein-coupled formyl peptide receptors (FPRs), which are expressed by immune cells of the central nervous system. FPRs show a broad spectrum of ligands, including pro- and anti-inflammatory ones. Here, we investigated the effects of the annexin A1 mimetic peptide Ac2-26 in a mouse model of pneumococcal meningitis. METHODS: Wildtype (WT) and Fpr1- and Fpr2-deficient mice were intrathecally infected with Streptococcus pneumoniae D39 (type 2). Subsequently, the different mice groups were treated by intraperitoneal injections of Ac2-26 (1 mg/kg body weight) 2, 8, and 24 h post-infection. The extent of inflammation was analyzed in various brain regions by means of immunohistochemistry and real-time reverse transcription polymerase chain reaction (RT-PCR) 30 h post-infection. RESULTS: Ac2-26-treated WT mice showed less severe neutrophil infiltration, paralleled by a reduced induction of pro-inflammatory glial cell responses in the hippocampal formation and cortex. While meningitis was ameliorated in Ac2-26-treated Fpr1-deficient mice, this protective effect was not observed in Fpr2-deficient mice. Irrespective of Ac2-26 treatment, inflammation was more severe in Fpr2-deficient compared to Fpr1-deficient mice. CONCLUSIONS: In summary, this study demonstrates anti-inflammatory properties of Ac2-26 in a model of bacterial meningitis, which are mediated via FPR2, but not FPR1. Ac2-26 and other FPR2 modulators might be promising targets for the development of novel therapies for Streptococcus pneumoniae-induced meningitis.

Harnessing inflammation resolving-based therapeutic agents to treat pulmonary viral infections: What can the future offer to COVID-19?

Inflammation is generally accepted as a component of the host defence system and a protective response in the context of infectious diseases. However, altered inflammatory responses can contribute to disease in infected individuals. Many endogenous mediators that drive the resolution of inflammation are now known. Overall, mediators of resolution tend to decrease inflammatory responses and provide normal or greater ability of the host to deal with infection. In the lung, it seems that pro-resolution molecules, or strategies that promote their increase, tend to suppress inflammation and lung injury and facilitate control of bacterial or viral burden. Here, we argue that the demonstrated anti-inflammatory, pro-resolving, anti-thrombogenic and anti-microbial effects of such endogenous mediators of resolution may be useful in the treatment of the late stages of the disease in patients with COVID-19.

Annexin A1 attenuates neuroinflammation through FPR2/p38/COX-2 pathway after intracerebral hemorrhage in male mice.

Spontaneous intracerebral hemorrhage (ICH) is the deadliest stroke subtype and neuroinflammation is a critical component of the pathogenesis following ICH. Annexin A1-FPR2 signaling has been shown to play a protective role in animal stroke models. This study aimed to assess whether Annexin A1 attenuated neuroinflammation and brain edema after ICH and investigate the underlying mechanisms. Male CD-1 mice were subjected to collagenase-induced ICH. Annexin A1 was administered at 0.5 hr after ICH. Brain water content measurement, short-term and long-term neurobehavioral tests, Western blot and immnunofluorescence were performed. Results showed that Annexin A1 effectively attenuated brain edema, improved short-term neurological function and ameliorated microglia activation after ICH. Annexin A1 also improved memory function at 28 days after ICH. However, these beneficial effects were abolished with the administration of FPR2 antagonist Boc-2. Furthermore, AnxA1/FPR2 signaling may confer protective effects via inhibiting p38-associated inflammatory cascade. Our study demonstrated that Annexin A1/FPR2/p38 signaling pathway played an important role in attenuating neuroinflammation after ICH and that Annexin A1 could be a potential therapeutic strategy for ICH patients.

Annexin A1-derived peptide Ac2-26 in a pilocarpine-induced status epilepticus model: anti-inflammatory and neuroprotective effects.

BACKGROUND: The inflammatory process has been described as a crucial mechanism in the pathophysiology of temporal lobe epilepsy. The anti-inflammatory protein annexin A1 (ANXA1) represents an interesting target in the regulation of neuroinflammation through the inhibition of leukocyte transmigration and the release of proinflammatory mediators. In this study, the role of the ANXA1-derived peptide Ac2-26 in an experimental model of status epilepticus (SE) was evaluated. METHODS: Male Wistar rats were divided into Naive, Sham, SE and SE+Ac2-26 groups, and SE was induced by intrahippocampal injection of pilocarpine. In Sham animals, saline was applied into the hippocampus, and Naive rats were only handled. Three doses of Ac2-26 (1 mg/kg) were administered intraperitoneally (i.p.) after 2, 8 and 14 h of SE induction. Finally, 24 h after the experiment-onset, rats were euthanized for analyses of neuronal lesion and inflammation. RESULTS: Pilocarpine induced generalised SE in all animals, causing neuronal damage, and systemic treatment with Ac2-26 decreased neuronal degeneration and albumin levels in the hippocampus. Also, both SE groups showed an intense influx of microglia, which was corroborated by high levels of ionised calcium binding adaptor molecule 1(Iba-1) and monocyte chemoattractant protein-1 (MCP-1) in the hippocampus. Ac2-26 reduced the astrocyte marker (glial fibrillary acidic protein; GFAP) levels, as well as interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and growth-regulated alpha protein (GRO/KC). These effects of the peptide were associated with the modulation of the levels of formyl peptide receptor 2, a G-protein-coupled receptor that binds to Ac2-26, and the phosphorylated extracellular signal-regulated kinase (ERK) in the hippocampal neurons. CONCLUSIONS: The data suggest a neuroprotective effect of Ac2-26 in the epileptogenic processes through downregulation of inflammatory mediators and neuronal loss.

Mimetic peptide AC2-26 of annexin A1 as a potential therapeutic agent to treat COPD.

Chronic obstructive pulmonary disease (COPD) is related to inflammatory process caused by smoking habit. In this scenario, the anti-inflammatory protein Annexin A1 (AnxA1) may represent a therapeutic alternative. We performed experiments to evaluate the effects of the AnxA1 mimetic peptide Ac2-26 in an initial COPD model by physiological, histopathological, biochemical and immunohistochemical analyses. Weight loss, increased blood pressure, reductions in the pulmonary frequency and ventilation, loss of tracheal cilia, enlargement of the pulmonary intra-alveolar spaces and lymphoid tissue found in untreated smoke-exposed group were attenuated by AnxA1 peptide treatment. The Ac2-26 administration also protected against leukocytes influx in bronchoalveolar lavage (BAL), lung and trachea, and it also led to decreased hemoglobin, glucose, cholesterol, gamma glutamyl transferase and aspartato aminotransferase levels. Similarly, reduction of proinflammatory mediators and higher concentration of anti-inflammatory cytokine were found in macerated lung supernatant, blood plasma and BAL in the treated animals. Besides Ac2-26 group showed reduced tissue expressions of AnxA1, cyclooxygenase-2 and metalloproteinase-9, but formylated peptide receptor 2 (FPR2) overexpression. Our results all together highlighted the protective role of the Ac2-26 mimetic peptide in COPD with promising perspectives.

Therapeutic Potential of Annexin A1 in Ischemia Reperfusion Injury.

Cardiovascular disease (CVD) continues to be the leading cause of death in the world. Increased inflammation and an enhanced thrombotic milieu represent two major complications of CVD, which can culminate into an ischemic event. Treatment for these life-threatening complications remains reperfusion and restoration of blood flow. However, reperfusion strategies may result in ischemia-reperfusion injury (I/RI) secondary to various cardiovascular pathologies, including myocardial infarction and stroke, by furthering the inflammatory and thrombotic responses and delivering inflammatory mediators to the affected tissue. Annexin A1 (AnxA1) and its mimetic peptides are endogenous anti-inflammatory and pro-resolving mediators, known to have significant effects in resolving inflammation in a variety of disease models. Mounting evidence suggests that AnxA1, which interacts with the formyl peptide receptor (FPR) family, may have a significant role in mitigating I/RI associated complications. In this review article, we focus on how AnxA1 plays a protective role in the I/R based vascular pathologies.

Annexin A1 promotes timely resolution of inflammation in murine gout.

Gout is a self-limited inflammatory disease caused by deposition of monosodium urate (MSU) crystals in the joints. Resolution of inflammation is an active process leading to restoration of tissue homeostasis. Here, we studied the role of Annexin A1 (AnxA1), a glucocorticoid-regulated protein that has anti-inflammatory and proresolving actions, in resolution of acute gouty inflammation. Injection of MSU crystals in the knee joint of mice induced inflammation that was associated with expression of AnxA1 during the resolving phase of inflammation. Neutralization of AnxA1 with antiserum or blockade of its receptor with BOC-1 (nonselective) or WRW4 (selective) prevented the spontaneous resolution of gout. There was greater neutrophil infiltration after challenge with MSU crystals in AnxA1 knockout mice (AnxA1-/- ) and delayed resolution associated to decreased neutrophil apoptosis and efferocytosis. Pretreatment of mice with AnxA1-active N-terminal peptide (Ac2-26 ) decreased neutrophil influx, IL-1ß, and CXCL1 production in periarticular joint. Posttreatment with Ac2-26 decreased neutrophil accumulation, IL-1ß, and hypernociception, and improved the articular histopathological score. Importantly, the therapeutic effects of Ac2-26 were associated with increased neutrophils apoptosis and shortened resolution intervals. In conclusion, AnxA1 plays a crucial role in the context of acute gouty inflammation by promoting timely resolution of inflammation.

Mecanismos de modulação da ANXA1 sobre a função da proteína translocadora (TSPO) em células da glia (OU) Mecanismos de modulação da anexina A1 sobre a função da proteína translocadora em células da glia / Annexin A1 modulation mechanism on the expression of the Translocator Protein (TSPO) in BV2 cells

A inflamação no sistema nervoso central (SNC) está envolvida na gênese de uma série de doenças neurodegenerativas, sendo assim, compreender o processo inflamatório nessas circunstâncias se torna essencial para propor novas abordagens terapêuticas. Sabemos que a Anexina A1 (ANXA1) e o receptor TSPO são dois moduladores importantes da neuroinflamação. Enquanto se sabe que a ANXA1 possui propriedades antiinflamatórias, o papel do TSPO ainda não está esclarecido. Desta forma, este projeto avaliou a atuação da ANXA1 sobre a expressão do TSPO em linhagem de células da microglia (BV2), e sua conexão com o receptor Toll-like receptor-4 (TLR4) em BV2 ativada pelo lipopolisacarídeo de E.coli (LPS). Os resultados obtidos mostram que o tratamento de BV2 com LPS induz a expressão de TSPO, dependente de ativação de TLR4, através das vias da molécula adaptadora do fator de diferenciação mielóide 88 (MyD88) e do fator nuclear κB (NFκB). O tratamento com ANXA1 recombinante induz um perfil antiinflamatório em células BV2 estimuladas com LPS, por reduzir a secreção de citocinas proinflamatórias e, ao mesmo tempo, aumentar secreção de citocinas antiinflamatórias. A exposição com ANXA1 ainda impede o aumento da expressão de TSPO induzida pelo LPS. Mostramos também que esta ação da ANXA1 é dependente da interação com o receptor de peptídeo formilado (FPR2). Adicionalmente, o silenciamento de TSPO em células BV2 predispõe essas células a um perfil ativado exacerbando a secreção do fator de necrose tumoral (TNFα) em resposta ao LPS, o que não pode ser revertido pelo tratamento com ANXA1 recombinante. Em conjunto, os resultados expõe a relação existente entre ANXA1 e TSPO em micróglia ativada pelo LPS, mostrando que a ANXA1 9 modula negativamente a expressão do TSPO. Ademais, o silenciamento de TSPO inibiu a fagocitose de neurônios apoptóticos, o que ainda sugere a participação do TSPO na eferocitose

Inflammation in the Central Nervous System (CNS) is involved in the genesis of a number of neurodegenerative diseases, so understanding the inflammatory process in these circumstances is essential to proposal new therapeutic approaches. We know that Annexin A1 (ANXA1) and the TSPO receptor are two important modulators of neuroinflammation. While it is known that ANXA1 has anti-inflammatory properties, the role of TSPO has not yet been clarified. Thus, this project evaluated the interference of ANXA1 on the expression of TSPO in microglia cell line (BV2), and its connection with the Toll-like receptor-4 receptor (TLR4) in BV2 activated by E. coli lipopolysaccharide LPS). The results show that the treatment of BV2 with LPS induces the expression of TSPO, dependent on activation of TLR4, through the pathways of the adapter molecule of myeloid differentiation factor 88 (MyD88) and nuclear factor κB (NFκB). Treatment with recombinant ANXA1 induces an anti-inflammatory profile in LPS-stimulated BV2 cells, by reducing the secretion of proinflammatory cytokines and, at the same time, increasing secretion of anti-inflammatory cytokines. Exposure with ANXA1 still prevents the increase of LPS-induced TSPO expression. We also show that this action of ANXA1 is dependent on the interaction with the formylated peptide receptor (FPR2). In addition, TSPO silencing in BV2 cells predisposes these cells to an activated profile exacerbating secretion of tumor necrosis factor (TNFα) in response to LPS, which can not be reversed by treatment with recombinant ANXA1. Together, the results show the relationship between ANXA1 and TSPO in LPS activated microglia, showing that ANXA1 negatively modulates TSPO 11 expression. In addition, TSPO silencing inhibited the phagocytosis of apoptotic neurons, which still suggests the participation of TSPO in eferocytosis

Anti-inflammatory and anti-fibrotic effects of annexin1 on erectile function after cavernous nerve injury in rats.

The aim of this study was to investigate the effect of the anti-inflammatory and anti-fibrotic actions of ANX1 on erectile function (EF). Forty-eight male Wistar rats were randomly distributed into four equal groups: one group (sham operation-control) and three groups (bilateral cavernous nerve (CN) crush injury). Crush injury groups were treated prior to injury with an intravascular injection of either ANX1 (50 or 100 µg kg-1) or vehicle. EF was assessed by CN electrical stimulation at 2 and 7 days after CN injury with histomorphometric and immunohistochemical analysis. ANX1 demonstrated functional preservation as the increase in intracavernous pressure (ICP). A dose-response relationship regarding the effect on penile tissue was confirmed, and preservation of the penile dorsal nerves and anti-apoptotic effects in the corpus cavernosum (real P-value vs injured control). ANX1 treatment prevented collagen deposition and smooth muscle loss in the penis. ANX1 normalized the expression of vascular endothelial growth factor and decreased tumor necrosis factor-α in the lumen of the blood vessels of the organ. ANX1 proved effective in preserving EF in a rat model of neurogenic erectile dysfunction. ANX1 treatment before CN injury in rats improved erectile recovery, enhanced vascular regeneration and preserved the micro-architecture of the corpus cavernosum. The clinical availability of this compound merits application in penile rehabilitation studies following radical prostatectomy.

Formyl-Peptide Receptor 2/3/Lipoxin A4 Receptor Regulates Neutrophil-Platelet Aggregation and Attenuates Cerebral Inflammation: Impact for Therapy in Cardiovascular Disease.

BACKGROUND: Platelet activation at sites of vascular injury is essential for hemostasis, but it is also a major pathomechanism underlying ischemic injury. Because anti-inflammatory therapies limit thrombosis and antithrombotic therapies reduce vascular inflammation, we tested the therapeutic potential of 2 proresolving endogenous mediators, annexin A1 N-terminal derived peptide (AnxA1Ac2-26) and aspirin-triggered lipoxin A4 (15-epi-lipoxin A4), on the cerebral microcirculation after ischemia/reperfusion injury. Furthermore, we tested whether the lipoxin A4 receptor formyl-peptide receptor 2/3 (Fpr2/3; ortholog to human FPR2/lipoxin A4 receptor) evoked neuroprotective functions after cerebral ischemia/reperfusion injury. METHODS AND RESULTS: Using intravital microscopy, we found that cerebral ischemia/reperfusion injury was accompanied by neutrophil and platelet activation and neutrophil-platelet aggregate formation within cerebral microvessels. Moreover, aspirin-triggered lipoxin A4 activation of neutrophil Fpr2/3 regulated neutrophil-platelet aggregate formation in the brain and inhibited the reactivity of the cerebral microvasculature. The same results were obtained with AnxA1Ac2-26 administration. Blocking Fpr2/lipoxin A4 receptor with the antagonist Boc2 reversed this effect, and treatments were ineffective in Fpr2/3 knockout mice, which displayed an exacerbated disease severity, evidenced by increased infarct area, blood-brain barrier dysfunction, increased neurological score, and elevated levels of cytokines. Furthermore, aspirin treatment significantly reduced cerebral leukocyte recruitment and increased endogenous levels of aspirin-triggered lipoxin A4, effects again mediated by Fpr2/3. CONCLUSION: Fpr2/lipoxin A4 receptor is a therapeutic target for initiating endogenous proresolving, anti-inflammatory pathways after cerebral ischemia/reperfusion injury.

The role of the Wnt/ß-catenin-Annexin A1 pathway in the process of sevoflurane-induced cognitive dysfunction.

Postoperative cognitive decline (POCD) is a common geriatric complication, and sevoflurane is a widely accepted inducer of POCD. Although the aetiology of POCD is not clear, a breach in the blood-brain barrier (BBB) is involved in early POCD. Annexin A1 has shown protective effects on BBB function. The objective of this study was to investigate both the effects of sevoflurane on the components of the BBB and the underlying mechanism. In vivo treatment with 3.6% sevoflurane for 6 h disrupted BBB components led to fibrinogen invasion and down-regulation of Annexin A1 expression at 24 h after inhalation. The administration of human recombinant Annexin A1 (hr Annexin A1) attenuated the disruption of BBB components, thereby reducing fibrinogen invasion. In addition, the administration of hr Annexin A1 improved cognitive function after the inhalation of 3.6% sevoflurane for 6 h. Moreover, in cultured endothelial cells, 3.6% sevoflurane for 6 h increased GSK-3ß and decreased ß-catenin levels at 24 h after inhalation. The activation/inhibition of the Wnt/ß-catenin signalling pathway attenuated/worsened the sevoflurane-induced decrease in Annexin A1. Our findings indicate that in endothelial cells, treatment with 3.6% sevoflurane for 6 h inhibits the Wnt/ß-catenin signalling pathway, thereby increasing GSK-3ß and decreasing ß-catenin. By inhibiting this pathway, the gas anaesthetic sevoflurane down-regulated Annexin A1, which consequently breached the BBB and induced POCD. We propose the following cascade for sevoflurane-induced cognitive dysfunction: in microvascular endothelial cells, treatment with 3.6% sevoflurane for 6 h inhibits the Wnt/ß-catenin signalling pathway, increasing GSK-3ß and decreasing ß-catenin, which down-regulates the expression of Annexin A1. This cascade leads to a breach in the blood-brain barrier, a process which is involved in the occurrence of early postoperative cognitive decline. Cover Image for this issue: doi: 10.1111/jnc.13314.

Beneficial effect of annexin A1 in a model of experimental allergic conjunctivitis.

Annexin A1 (ANXA1), a 37 kDa glucocorticoid-regulated protein, is a potent anti-inflammatory mediator effective in terminating acute inflammatory response, and its role in allergic settings has been poorly studied. The aim of this investigation was to evaluate the mechanism of action of ANXA1 in intraocular inflammation using a classical model of ovalbumin (OVA)-induced allergic conjunctivitis (AC). OVA-immunised Balb/c mice, wild-type (WT) and ANXA1-deficient (AnxA1(-/-)), were challenged with eye drops containing OVA on days 14-16 with a subset of WT animals pretreated intraperitoneally with the peptide Ac2-26 (N-terminal region of ANXA1) or dexamethasone (DEX). After 24 h of the last ocular challenge, WT mice treated with Ac2-26 and DEX had significantly reduced clinical signs of conjunctivitis (chemosis, conjunctival hyperaemia, lid oedema and tearing), plasma IgE levels, leukocyte (eosinophil and neutrophil) influx and mast cell degranulation in the conjunctiva compared to WT controls. These anti-inflammatory effects of DEX were associated with high endogenous levels of ANXA1 in the ocular tissues as detected by immunohistochemistry. Additionally, Ac2-26 administration was effective to reduce IL-2, IL-4, IL-10, IL-13, eotaxin and RANTES in the eye and lymph nodes compared to untreated WT animals. The lack of ANXA1 produced an exacerbated allergic response as detected by the density of the inflammatory cell influx to the conjunctiva and the cytokine/chemokine release. These different effects observed for Ac2-26 were correlated with diminished level of activated ERK at 24 h in the ocular tissues compared to untreated OVA group. Our findings demonstrate the protective effect of ANXA1 during the inflammatory allergic response suggesting this protein as a potential target for new ocular inflammation therapies.

Cardioprotective potential of annexin-A1 mimetics in myocardial infarction.

Myocardial infarction (MI) and its resultant heart failure remains a major cause of death in the world. The current treatments for patients with MI are revascularization with thrombolytic agents or interventional procedures. These treatments have focused on restoring blood flow to the ischemic tissue to prevent tissue necrosis and preserve organ function. The restoration of blood flow after a period of ischemia, however, may elicit further myocardial damage, called reperfusion injury. Pharmacological interventions, such as antioxidant and Ca(2+) channel blockers, have shown premises in experimental settings; however, clinical studies have shown limited success. Thus, there is a need for the development of novel therapies to treat reperfusion injury. The therapeutic potential of glucocorticoid-regulated anti-inflammatory mediator annexin-A1 (ANX-A1) has recently been recognized in a range of systemic inflammatory disorders. ANX-A1 binds to and activates the family of formyl peptide receptors (G protein-coupled receptor family) to inhibit neutrophil activation, migration and infiltration. Until recently, studies on the cardioprotective actions of ANX-A1 and its peptide mimetics (Ac2-26, CGEN-855A) have largely focused on its anti-inflammatory effects as a mechanism of preserving myocardial viability following I-R injury. Our laboratory provided the first evidence of the direct protective action of ANX-A1 on myocardium, independent of inflammatory cells in vitro. We now review the potential for ANX-A1 based therapeutics to be seen as a "triple shield" therapy against myocardial I-R injury, limiting neutrophil infiltration and preserving both cardiomyocyte viability and contractile function. This novel therapy may thus represent a valuable clinical approach to improve outcome after MI.