The anti-inflammatory peptides, antiflammins, regulate the expression of adhesion molecules on human leukocytes and prevent neutrophil adhesion to endothelial cells

Inflammation Resolution in the Cardiovascular System: Arterial Hypertension, Atherosclerosis, and Ischemic Heart Disease

Significance: Chronic inflammation has emerged as a major underlying cause of many prevalent conditions in the Western world, including cardiovascular diseases. Although targeting inflammation has emerged as a promising avenue by which to treat cardiovascular disease, it is also associated with increased risk of infection. Recent Advances: Though previously assumed to be passive, resolution has now been identified as an active process, mediated by unique immunoresolving mediators and mechanisms designed to terminate acute inflammation and promote tissue repair. Recent work has determined that failures of resolution contribute to chronic inflammation and the progression of human disease. Specifically, failure to produce pro-resolving mediators and the impaired clearance of dead cells from inflamed tissue have been identified as major mechanisms by which resolution fails in disease. Critical Issues: Drawing from a rapidly expanding body of experimental and clinical studies, we review here what is known about the role of inflammation resolution in arterial hypertension, atherosclerosis, myocardial infarction, and ischemic heart disease. For each, we discuss the involvement of specialized pro-resolving mediators and pro-reparative cell types, including T regulatory cells, myeloid-derived suppressor cells, and macrophages. Future Directions: Pro-resolving therapies offer the promise of limiting chronic inflammation without impairing host defense. Therefore, it is imperative to better understand the mechanisms underlying resolution to identify therapeutic targets. Antioxid. Redox Signal. 40, 292-316.

AIPs-SnTCN: Predicting Anti-Inflammatory Peptides Using fastText and Transformer Encoder-Based Hybrid Word Embedding with Self-Normalized Temporal Convolutional Networks

Inflammation is a biologically resistant response to harmful stimuli, such as infection, damaged cells, toxic chemicals, or tissue injuries. Its purpose is to eradicate pathogenic micro-organisms or irritants and facilitate tissue repair. Prolonged inflammation can result in chronic inflammatory diseases. However, wet-laboratory-based treatments are costly and time-consuming and may have adverse side effects on normal cells. In the past decade, peptide therapeutics have gained significant attention due to their high specificity in targeting affected cells without affecting healthy cells. Motivated by the significance of peptide-based therapies, we developed a highly discriminative prediction model called AIPs-SnTCN to predict anti-inflammatory peptides accurately. The peptide samples are encoded using word embedding techniques such as skip-gram and attention-based bidirectional encoder representation using a transformer (BERT). The conjoint triad feature (CTF) also collects structure-based cluster profile features. The fused vector of word embedding and sequential features is formed to compensate for the limitations of single encoding methods. Support vector machine-based recursive feature elimination (SVM-RFE) is applied to choose the ranking-based optimal space. The optimized feature space is trained by using an improved self-normalized temporal convolutional network (SnTCN). The AIPs-SnTCN model achieved a predictive accuracy of 95.86% and an AUC of 0.97 by using training samples. In the case of the alternate training data set, our model obtained an accuracy of 92.04% and an AUC of 0.96. The proposed AIPs-SnTCN model outperformed existing models with an ∼19% higher accuracy and an ∼14% higher AUC value. The reliability and efficacy of our AIPs-SnTCN model make it a valuable tool for scientists and may play a beneficial role in pharmaceutical design and research academia.

Mechanisms Limiting Renal Tissue Protection and Repair in Glomerulonephritis

Glomerulonephritis are renal disorders resulting from different pathogenic mechanisms (i.e., autoimmunity, complement, inflammatory activation, etc.). Clarifying details of the pathogenic cascade is basic to limit the progression from starting inflammation to degenerative stages. The balance between tissue injury, activation of protective systems and renal tissue repair determines the final outcome. Induction of an oxidative stress is part of glomerular inflammation and activation of protective antioxidant systems has a crucial role in reducing tissue effects. The generation of highly reactive oxygen species can be evaluated in vivo by tracing the inner-layer content of phosphatidyl ethanolamine and phosphatidyl serine in cell membranes. Albumin is the major antioxidant in serum and the level of oxidized albumin is another indirect sign of oxidative stress. Studies performed in Gn, specifically in FSGS, showed a high degree of oxidation in most contexts. High levels of circulating anti-SOD2 antibodies, limiting the detoxyfing activity of SOD2, have been detected in autoimmune Gn(lupus nephritis and membranous nephropathy) in association with persistence of proteinuria and worsening of renal function. In renal transplant, high levels of circulating anti-Glutathione S-transferase antibodies have been correlated with chronic antibody rejection and progressive loss of renal function. Annexins, mainly ANXA1 and ANXA2, play a general anti-inflammatory effect by inhibiting neutrophil functions. Cytosolic ANXA1 is decreased in apoptotic neutrophils of patients with glomerular polyangitis in association with delayed apoptosis that is considered the mechanism for polyangitis. High circulating levels of anti-ANXA1 and anti-ANXA2 antibodies characterize lupus nephritis implying a reduced anti-inflammatory effect. High circulating levels of antibodies targeting Macrophages (anti-FMNL1) have been detected in Gn in association with proteinuria. They potentially modify the intra-glomerular presence of protective macrophages (M2a, M2c) thus acting on the composition of renal infiltrate and on tissue repair.

Annexin A1 Is Associated with Adverse Clinical Outcomes in Patients with COVID-19

Severe coronavirus disease 2019 (COVID-19) is characterized by hyperinflammation, vascular damage, and hypercoagulability. Insufficient responses of Annexin A1 (AnxA1), a pro-resolving inhibitor of neutrophil infiltration and activation, might contribute to a severe course of the disease. We longitudinally evaluated AnxA1's role in terms of inflammation, vascular damage, and clinical outcomes in a large prospective cohort of patients with COVID-19. AnxA1 was measured at presentation and during follow-up in the sera of 220 consecutive patients who presented at our hospital during the first wave. AnxA1 was significantly higher in the moderate and severe cases of COVID-19 compared to the healthy controls. Elevated AnxA1 was associated with markers of inflammation and endothelial damage. AnxA1 was significantly higher in patients with thrombotic events and ICU admission. Multivariable logistic regression indicated baseline AnxA1 (per ten units) as a predictor of thrombotic events. Linear mixed models predicted that AnxA1 tended to increase more steeply over time in patients without adverse events, with a statistically significant rise in patients without thrombotic events. These findings might reflect an insufficient increase in AnxA1 as a response to the excessive hyperinflammation in COVID-19. Future studies should evaluate whether hyperinflammation could be reduced through the administration of human recombinant AnxA1 or Ac2-26 peptide.

Immunomodulatory peptides-A promising source for novel functional food production and drug discovery

Immunomodulatory peptides are a complex class of bioactive peptides that encompasses substances with different mechanisms of action. Immunomodulatory peptides could also be used in vaccines as adjuvants which would be extremely desirable, especially in response to pandemics. Thus, immunomodulatory peptides in food of plant origin could be regarded both as valuable suplements of novel functional food preparation and/or as precursors or possible active ingredients for drugs design for treatment variety of conditions arising from impaired function of immune system. Given variety of mechanisms, different tests are required to assess effects of immunomodulatory peptides. Some of those effects show good correlation with in vivo results but others, less so. Certain plant peptides, such as defensins, show both immunomodulatory and antimicrobial effect, which makes them interesting candidates for preparation of functional food and feed, as well as templates for design of synthetic peptides.

Inflammation Resolution: Implications for Atherosclerosis

Resolution is an active and highly coordinated process that occurs in response to inflammation to limit tissue damage and promote repair. When the resolution program fails, inflammation persists. It is now understood that failed resolution is a major underlying cause of many chronic inflammatory diseases. Here, we will review the major failures of resolution in atherosclerosis, including the imbalance of proinflammatory to pro-resolving mediator production, impaired clearance of dead cells, and functional changes in immune cells that favor ongoing inflammation. In addition, we will briefly discuss new concepts that are emerging as possible regulators of resolution and highlight the translational significance for the field.

AIEpred: An Ensemble Predictive Model of Classifier Chain to Identify Anti-Inflammatory Peptides

Anti-inflammatory peptides (AIEs) have recently emerged as promising therapeutic agent for treatment of various inflammatory diseases, such as rheumatoid arthritis and Alzheimer's disease. Therefore, detecting the correlation between amino acid sequence and its anti-inflammatory property is of great importance for the discovery of new AIEs. To address this issue, we propose a novel prediction tool for accurate identification of peptides as anti-inflammatory epitopes or non anti-inflammatory epitopes. Most of all, we encode the original peptide sequence for better mining and exploring the information and patterns, based on the three feature representations as amino acid contact, position specific scoring matrix, physicochemical property. At the same time, we exploit several feature extraction models and utilize one feature selection model, in order to construct many base classifiers from various feature representations. More specifically, we develop an effective classification model, with which we can extract and learn a set of informative features from the ensemble classifier chain model with different group of base classifiers. Furthermore, in order to test the predictive power of our model, we conduct the comparative experiments on the leave-one-out cross-validation and the independent test. It shows that our novel predictor performs great accurate for identification of AIEs as well as existing outstanding prediction tools. Source codes are available at https://github.com/guofei-tju/Ensemble-classifier-chain-model.

PreAIP: Computational Prediction of Anti-inflammatory Peptides by Integrating Multiple Complementary Features

Numerous inflammatory diseases and autoimmune disorders by therapeutic peptides have received substantial consideration; however, the exploration of anti-inflammatory peptides via biological experiments is often a time-consuming and expensive task. The development of novel in silico predictors is desired to classify potential anti-inflammatory peptides prior to in vitro investigation. Herein, an accurate predictor, called PreAIP (Predictor of Anti-Inflammatory Peptides) was developed by integrating multiple complementary features. We systematically investigated different types of features including primary sequence, evolutionary and structural information through a random forest classifier. The final PreAIP model achieved an AUC value of 0.833 in the training dataset via 10-fold cross-validation test, which was better than that of existing models. Moreover, we assessed the performance of the PreAIP with an AUC value of 0.840 on a test dataset to demonstrate that the proposed method outperformed the two existing methods. These results indicated that the PreAIP is an accurate predictor for identifying AIPs and contributes to the development of AIPs therapeutics and biomedical research. The curated datasets and the PreAIP are freely available at http://kurata14.bio.kyutech.ac.jp/PreAIP/.

Antiinflammatory peptides: current knowledge and promising prospects

BACKGROUND

Inflammation is part of the regular host reaction to injury or infection caused by toxic factors, pathogens, damaged cells, irritants, and allergens. Antiinflammatory peptides (AIPs) are present in all living organisms, and many peptides from herbal, mammalian, bacterial, and marine origins have been shown to have antimicrobial and/or antiinflammatory properties.

METHODS

In this study, we investigated the effects of antiinflammatory peptides on inflammation, and highlighted the underlying mechanisms responsible for these effects.

RESULTS

In multicellular organisms, including humans, AIPs constitute an essential part of their immune system. In addition, numerous natural and synthetic AIPs are effective immunomodulators and can interfere with signal transduction pathways involved in inflammatory cytokine expression. Among them, some peptides such as antiflammin, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), and those derived from velvet antler proteins, bee venom, horse fly salivary gland, and bovine β-casein have received considerable attention over the past few years.

CONCLUSION

This article presents an overview on the major properties and mechanisms of action associated with AIPs as immunomodulatory, chemotactic, antioxidant, and antimicrobial agents. In addition, the results of various studies dealing with effects of AIPs on numerous classical models of inflammation are reviewed and discussed.

Meta-Analysis for Correlating Structure of Bioactive Peptides in Foods of Animal Origin with Regard to Effect and Stability

Amino acid (AA) sequences of 807 bioactive peptides from foods of animal origin were examined in order to correlate peptide structure with activity (antihypertensive, antioxidative, immunomodulatory, antimicrobial, hypolipidemic, antithrombotic, and opioid) and stability in vivo. Food sources, such as milk, meat, eggs, and marine products, show different frequencies of bioactive peptides exhibiting specific effects. There is a correlation of peptide structure and effect, depending on type and position of AA. Opioid peptides contain a high percentage of aromatic AA residues, while antimicrobial peptides show an excess of positively charged AAs. AA residue position is significant, with those in the first and penultimate positions having the biggest effects on peptide activity. Peptides that have activity in vivo contain a high percentage (67%) of proline residues, but the positions of proline in the sequence depend on the length of the peptide. We also discuss the influence of processing on activity of these peptides, as well as methods for predicting release from the source protein and activity of peptides.

The role of non-resolving inflammation in atherosclerosis

Non-resolving inflammation drives the development of clinically dangerous atherosclerotic lesions by promoting sustained plaque inflammation, large necrotic cores, thin fibrous caps, and thrombosis. Resolution of inflammation is not merely a passive return to homeostasis, but rather an active process mediated by specific molecules, including fatty acid-derived specialized pro-resolving mediators (SPMs). In advanced atherosclerosis, there is an imbalance between levels of SPMs and proinflammatory lipid mediators, which results in sustained leukocyte influx into lesions, inflammatory macrophage polarization, and impaired efferocytosis. In animal models of advanced atherosclerosis, restoration of SPMs limits plaque progression by suppressing inflammation, enhancing efferocytosis, and promoting an increase in collagen cap thickness. This Review discusses the roles of non-resolving inflammation in atherosclerosis and highlights the unique therapeutic potential of SPMs in blocking the progression of clinically dangerous plaques.

Annexin A1 and Autoimmunity: From Basic Science to Clinical Applications

Annexin A1 is a protein with multifunctional roles in innate and adaptive immunity mainly devoted to the regulation of inflammatory cells and the resolution of inflammation. Most of the data regarding Annexin A1 roles in immunity derive from cell studies and from mice models lacking Annexin A1 for genetic manipulation (Annexin A1^−/−); only a few studies sought to define how Annexin A1 is involved in human diseases. High levels of anti-Annexin A1 autoantibodies have been reported in systemic lupus erythematosus (SLE), suggesting this protein is implicated in auto-immunity. Here, we reviewed the evidence available for an association of anti-Annexin A1 autoantibodies and SLE manifestations, in particular in those cases complicated by lupus nephritis. New studies show that serum levels of Annexin A1 are increased in patients presenting renal complications of SLE, but this increment does not correlate with circulating anti-Annexin A1 autoantibodies. On the other hand, high circulating Annexin A1 levels cannot explain per se the development of autoantibodies since post-translational modifications are necessary to make a protein immunogenic. A hypothesis is presented here and discussed regarding the possibility that Annexin A1 undergoes post-translational modifications as a part of neutrophil extracellular traps (NETs) that are produced in response to viral, bacterial, and/or inflammatory triggers. In particular, focus is on the process of citrullination of Annexin A1, which takes place within NETs and that mimics, to some extent, other autoimmune conditions, such as rheumatoid arthritis, that are characterized by the presence of anti-citrullinated peptides in circulation. The description of pathologic pathways leading to modification of Annexin A1 as a trigger of autoimmunity is a cognitive evolution, but requires more experimental data before becoming a solid concept for explaining autoimmunity in human beings.

Small but mighty: Platelets as central effectors of host defense

Platelets actively participate in inflammatory processes and drive diseases such as atherosclerosis, rheumatoid arthritis and cancer metastasis. However, platelets also have anti-inflammatory and anti-infective properties, which have received less consideration in the past. In this review, we highlight recent findings on the role of platelets in host defense and describe regulatory pathways modulating immuneresponses. Furthermore, we discuss the role of platelets for the resolution of inflammation and tissue repair. These conceptual changes contribute to our understanding of platelet biology in disease.

Prediction of anti-inflammatory proteins/peptides: an insilico approach

Background

The current therapy for inflammatory and autoimmune disorders involves the use of nonspecific anti-inflammatory drugs and other immunosuppressant, which are often accompanied with potential side effects. As an alternative therapy, anti-inflammatory peptides are recently being exploited as anti-inflammatory agents for treatment of various inflammatory diseases such as Alzheimer’s disease and rheumatoid arthritis. Thus, understanding the correlation between amino acid sequence and its potential anti-inflammatory property is of great importance for the discovery of novel and efficient anti-inflammatory peptide-based therapeutics.

Methods

In this study, we have developed a prediction tool for the classification of peptides as anti-inflammatory epitopes or non anti-inflammatory epitopes. The training was performed using experimentally validated epitopes obtained from Immune epitope database and analysis resource database. Different sequence-based features and their hybrids with motif information were employed for development of support vector machine-based machine learning models. Similarly, machine learning models were also constructed using random forest.

Results

The composition and terminal residue conservation analysis of peptides revealed the dominance of leucine, serine, tyrosine and arginine residues in anti-inflammatory epitopes as compared to non anti-inflammatory epitopes. Similarly, the anti-inflammatory epitopes specific motifs were found to be rich in hydrophobic and polar residues. The hybrid of tripeptide composition-based support vector machine model and motif yielded the best performance on 10-fold cross validation with an accuracy of 78.1% and MCC of 0.58. The same displayed an accuracy of 72% and MCC of 0.45 on validation dataset, rejecting any possibility of over-fitting. The tripeptide composition-based random forest model displayed an accuracy of 0.8 and MCC of 0.59 on 10-fold cross validation, however, the accuracy (0.68) and MCC (0.31) was lower as compared to support vector machine model on validation dataset. Thus, the support vector machine model is implemented as the default model and an additional option of using the random forest model is provided.

Conclusion

The prediction models along with tools for epitope mapping and similarity search have been provided as a web server which is freely accessible at http://metagenomics.iiserb.ac.in/antiinflam/.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1103-6) contains supplementary material, which is available to authorized users.

The advantageous role of annexin A1 in cardiovascular disease

The inflammatory response protects the human body against infection and injury. However, uncontrolled and unresolved inflammation can lead to tissue damage and chronic inflammatory diseases. Therefore, active resolution of inflammation is essential to restore tissue homeostasis. This review focuses on the pro-resolving molecule annexin A1 (ANXA1) and its derived peptides. Mechanisms instructed by ANXA1 are multidisciplinary and affect leukocytes as well as endothelial cells and tissue resident cells like macrophages and mast cells. ANXA1 has an outstanding role in limiting leukocyte recruitment and different aspects of ANXA1 as modulator of the leukocyte adhesion cascade are discussed here. Additionally, this review details the therapeutic relevance of ANXA1 and its derived peptides in cardiovascular diseases since atherosclerosis stands out as a chronic inflammatory disease with impaired resolution and continuous leukocyte recruitment.

Annexin A1 and the Resolution of Inflammation: Modulation of Neutrophil Recruitment, Apoptosis, and Clearance

Neutrophils (also named polymorphonuclear leukocytes or PMN) are essential components of the immune system, rapidly recruited to sites of inflammation, providing the first line of defense against invading pathogens. Since neutrophils can also cause tissue damage, their fine-tuned regulation at the inflammatory site is required for proper resolution of inflammation. Annexin A1 (AnxA1), also known as lipocortin-1, is an endogenous glucocorticoid-regulated protein, which is able to counterregulate the inflammatory events restoring homeostasis. AnxA1 and its mimetic peptides inhibit neutrophil tissue accumulation by reducing leukocyte infiltration and activating neutrophil apoptosis. AnxA1 also promotes monocyte recruitment and clearance of apoptotic leukocytes by macrophages. More recently, some evidence has suggested the ability of AnxA1 to induce macrophage reprogramming toward a resolving phenotype, resulting in reduced production of proinflammatory cytokines and increased release of immunosuppressive and proresolving molecules. The combination of these mechanisms results in an effective resolution of inflammation, pointing to AnxA1 as a promising tool for the development of new therapeutic strategies to treat inflammatory diseases.

Multi-antibody composition in lupus nephritis: isotype and antigen specificity make the difference

Research on autoimmune processes involved in glomerulonephritis has been for years based on experimental models. Recent progress in proteomics has radically modified perspectives: laser microdissection and proteomics were crucial for an in vivo analysis of autoantibodies eluted from human biopsies. Lupus nephritis has been the subject of recent independent researches. Main topics have been the definition of renal autoimmune components in human lupus biopsies; methods were laser capture of glomeruli and/or of single cells (CD38+ or Ki-67+) from tubulointerstitial areas as starting step followed by elution and characterization of renal antibodies by proteomics. The innovative approach highlighted different panels of autoantibodies deposited in glomeruli and in tubulo-interstitial areas that actually represented the unique autoimmune components in these patients. IgG2 was the major isotype; new podocyte proteins (αenolase, annexin AI) and already known implanted molecules (DNA, histone 3, C1q) were their target antigens in glomeruli. Vimentin was the antigen in tubulo-interstitial areas. Matching renal autoantibodies with serum allowed the definition of a typical autoantibody serum map that included the same anti-αenolase, anti-annexin AI, anti-DNA, and anti-histone 3 IgG2 already detected in renal tissue. Serum levels of specific autoantibodies were tenfold increased in patients with lupus nephritis allowing a clear differentiation from both rheumatoid arthritis and other glomerulonephritis. In all cases, targeted antigens were characterized as components of lupus NETosis. Matching renal/serum autoantibody composition in vivo furnishes new insights on human lupus nephritis and allows to refine composition of circulating antibodies in patients with lupus. A thoughtful passage from bench to bedside of new knowledge would expand our clinical and therapeutic opportunities.

Antiflammin-1 attenuates bleomycin-induced pulmonary fibrosis in mice

BACKGROUND

Antiflammin-1 (AF-1), a derivative of uteroglobin (UG), is a synthetic nonapeptide with diverse biological functions. In the present study, we investigated whether AF-1 has a protective effect against bleomycin-induced pulmonary fibrosis.

METHODS

C57BL/6 mice were injected with bleomycin intratracheally to create an animal model of bleomycin-induced pulmonary fibrosis. On Day 7 and Day 28, we examined the anti-inflammatory effect and antifibrotic effect, respectively, of AF-1 on the bleomycin-treated mice. The effects of AF-1 on the transforming growth factor-beta 1 (TGF-β1)-induced proliferation of murine lung fibroblasts (NIH3T3) were examined by a bromodeoxycytidine (BrdU) incorporation assay and cell cycle analysis.

RESULTS

Severe lung inflammation and fibrosis were observed in the bleomycin-treated mice on Day 7 and Day 28, respectively. Administration of AF-1 significantly reduced the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in the lung homogenates on Day 7. Histological examination revealed that AF-1 markedly reduced the number of infiltrating cells on Day 7 and attenuated the collagen deposition and destruction of lung architecture on Day 28. The hydroxyproline (HYP) content was significantly decreased in the AF-1-treated mice. In vitro, AF-1 inhibited the TGF-β1-induced proliferation of NIH3T3 cells, which was mediated by the UG receptor.

CONCLUSIONS

AF-1 has anti-inflammatory and antifibrotic actions in bleomycin-induced lung injury. We propose that the antifibrotic effect of AF-1 might be related to its suppression of fibroblast growth in bleomycin-treated lungs and that AF-1 has potential as a new therapeutic tool for pulmonary fibrosis.

Evidence for operation of nicotinic and muscarinic acetylcholine receptor-dependent survival pathways in human coronary artery endothelial cells

Nicotinic acetylcholine receptors (nAChRs) have recently emerged as critical players in modulation of endothelial function. In particular, studies on endothelial cells from different vascular beds have shown anti-apoptotic actions of nicotinic stimulation, but whether there is actually activation of survival signaling downstream nAChR function has not been explored. In the present work we used human coronary artery endothelial cells (HCAECs) and a pharmacological approach to examine the impact of cholinergic stimulation on survival signaling pathways. Our findings show that cholinergic receptors promote activation of three typical survival routes: the phosphatidyl-inositol-3-kinase (PI3K)/AKT axis, activated downstream muscarinic and nAChRs; the JAK2/STAT3 axis, activated downstream nAChR; and ERK1/2 MAP kinases, activated by both muscarinic acetylcholine receptor (mAChR) and nAChR. Based on their sensitivity to α-bungarotoxin, nicotinic regulation of JAK2/STAT3 and ERK1/2 occurs downstream α7-nAChRs. The present findings suggest that in HCAECs the two cholinergic receptors may act concertedly to induce an efficient survival response of coronary cells when exposed to pro-apoptotic stimuli.

Evidence for an anti-inflammatory loop centered on polymorphonuclear leukocyte formyl peptide receptor 2/lipoxin A4 receptor and operative in the inflamed microvasculature

The importance of proresolving mediators in the overall context of the resolution of acute inflammation is well recognized, although little is known about whether these anti-inflammatory and proresolving molecules act in concert. In this article, we focused on lipoxin A(4) (LXA(4)) and annexin A1 (AnxA1) because these two very different mediators converge on a single receptor, formyl peptide receptor type 2 (FPR2/ALX). Addition of LXA(4) to human polymorphonuclear leukocytes (PMNs) provoked a concentration- and time-dependent mobilization of AnxA1 onto the plasma membrane, as determined by Western blotting and flow cytometry analyses. This property was shared by another FPR2/ALX agonist, antiflammin-2, and partly by fMLF or peptide Ac2-26 (an AnxA1 derivative that can activate all three members of the human FPR family). An FPR2/ALX antagonist blocked AnxA1 mobilization activated by LXA(4) and antiflammin-2. Analysis of PMN degranulation patterns and phospho-AnxA1 status suggested a model in which the two FPR2/ALX agonists mobilize the cytosolic (and not the granular) pool of AnxA1 through an intermediate phosphorylation step. Intravital microscopy investigations of the inflamed mesenteric microvasculature of wild-type and AnxA1(-/-) mice revealed that LXA(4) provoked leukocyte detachment from the postcapillary venule endothelium in the former (>50% within 10 min; p < 0.05), but not the latter genotype (∼15%; NS). Furthermore, recruitment of Gr1(+) cells into dorsal air-pouches, inflamed with IL-1β, was significantly attenuated by LXA(4) in wild-type, but not AnxA1(-/-), mice. Collectively, these data prompt us to propose the existence of an endogenous network in anti-inflammation centered on PMN AnxA1 and activated by selective FPR2/ALX agonists.

Therapeutic anti-inflammatory potential of formyl-peptide receptor agonists

The need for novel anti-inflammatory drugs justifies the search for innovative targets that could satisfy this goal. For quite some time now, we have proposed the study of endogenous anti-inflammation as a distinctive approach to the discovery of new drugs. This approach requires development of new compounds that activate specific receptor targets to downregulate the cellular and tissue pathways operative in the host during inflammation. Here we dwell on a family of G-protein coupled receptors (GPCR) termed FPRs, acronym for formyl-peptide receptors. With three and seven members in man and mouse, respectively, these receptors harness many biological functions, spanning odour perception and hair growth, to the control of multiple facets (pain; cell migration; oxidative burst; xenobiotic engulfment) of the inflammatory reaction. We focus on FPR biology with particular attention to molecules able to produce pharmacological effects by interacting with these GPCRs, describing endogenous agonists of FPRs and, more relevantly, the current development of synthetic agonists. Besides being potential leads for the development of the anti-inflammatory therapeutics of the future, these compounds could also help clarify the properties and roles that each FPR might play in the complex network of pathways that is inflammation. We conclude that FPR2 agonists could be valid warhorses for defining a novel philosophy for anti-inflammatory drug discovery programmes: mimicking - with new compounds - the way our body disposes of inflammation could be a viable approach to regulate aberrant inflammatory responses as in the case of several chronic rheumatic and cardiovascular pathologies.

CFTR inhibition provokes an inflammatory response associated with an imbalance of the annexin A1 pathway

Cystic fibrosis (CF), a disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, is characterized by chronic bacterial infections and inflammation in the lung. Having previously shown that deletion of CFTR is associated with lower expression of the endogenous anti-inflammatory protein Annexin A1 (AnxA1), we investigated further this possible functional connection using a validated CFTR inhibitor. Treatment of mice with the CFTR inhibitor-172 (CFTR(172)) augmented the acute peritonitis promoted by zymosan, an effect associated with lower AnxA1 levels in peritoneal cells. Similar results were obtained with another, chemically distinct, CFTR inhibitor. The pro-inflammatory effect of CFTR(172) was lost in AnxA1(-/-), as well as CFTR(-/-) mice. Importantly, administration of hrAnxA1 and its peptido-mimetic to CFTR(-/-) animals or to animals treated with CFTR(172) corrected the exaggerated leukocyte migration seen in these animals. In vitro assays with human Polymorphonuclear leukocyte (PMN) demonstrated that CFTR(172) reduced cell-associated AnxA1 by promoting release of the protein in microparticles. We propose that the reduced impact of the counterregulatory properties of AnxA1 in CF cells contributes to the inflammatory phenotype characteristic of this disease. Thus, these findings provide an important insight into the mechanism underlying the inflammatory disease associated with CFTR inhibition while, at the same time, providing a novel pharmacological target for controlling the inflammatory phenotype of CF.

Exploiting the Annexin A1 pathway for the development of novel anti-inflammatory therapeutics

The appreciation that the inflammatory reaction does not 'spontaneously' finish, but rather that inflammatory resolution is an active phenomenon brought about by endogenous anti-inflammatory agonists opens multiple opportunities for a reassessment of the complexity of inflammation and its main mediators. This review dwells on one of these pathways, the one centred around the glucocorticoid-regulated protein Annexin A1 and its G protein-coupled receptor. In recent years, much of the knowledge detailing the processes by which Annexin A1 expresses its anti-inflammatory role on innate immunity has been produced. Moreover, the generation of the Annexin A1 null mouse colony has provided important proof-of-concept experiments demonstrating the inhibitory properties of this mediator in the context of inflammatory and/or tissue-injury models. Therefore, Annexin A1 acts as a pivotal homeostatic mediator, where if absent, inflammation would overshoot and be prolonged. This new understanding scientific information could guide us onto the exploitation of the biological properties of Annexin A1 and its receptor to instigate novel drug discovery programmes for anti-inflammatory therapeutics. This line of research relies on the assumption that anti-inflammatory drugs designed upon endogenous anti-inflammatory mediators would be burdened by a lower degree of secondary effects as these agonists would be mimicking specific pathways activated in our body for safe disposal of inflammation. We believe that the next few years will produce examples of such new drugs and the validity of this speculation could then be assessed.

Atorvastatin modifies the protein profile of circulating human monocytes after an acute coronary syndrome

Aggressive treatment with high-dose atorvastatin reduces more effectively the incidence of cardiovascular events than moderate statin therapy. The mechanism of this benefit has not been fully elucidated. In order to know the potential effects of statin treatment on the protein expression of circulating monocytes in acute coronary syndrome (ACS) patients, a proteomic analysis of these cells was carried out by 2-DE and MS. Twenty-five patients with non-ST-elevation acute coronary syndrome (NSTEACS) were randomized, the fourth day after admission, to receive ATV 80 mg/dL (n = 14) or conventional treatment (CT) (n = 11), for two months. Blood was withdrawn at the end of the treatment, and monocytes were extracted for proteomic analysis and their protein expression patterns determined. Age, sex, total cholesterol, LDL, HDL, triglycerides, body mass index, presence of hypertension, diabetes, and smoking status were not significantly different between the two groups of patients. The expression of 20 proteins was modified by intensive ATV. Among the most relevant results stand out the normalization by intensive ATV treatment of the expression of proteins that modulate inflammation and thrombosis such as protein disulfide isomerase ER60 (PDI), Annexin I, and prohibitin, or that have other protective effects as HSP-70. Thus, this approach shed light at the molecular level of the beneficial mechanisms of anti-atherothrombotic drugs.

Functional and ultrastructural analysis of annexin A1 and its receptor in extravasating neutrophils during acute inflammation

The purpose of this study was twofold: to reveal cellular events associated with the protective role of endogenous annexin A1 (AnxA1) in inflammation and to highlight the potential involvement of members of the formyl peptide receptor (Fpr) family in this process. We found that wild-type, AnxA1-null, and Fpr1-null mice all displayed an intense neutrophil recruitment into the peritoneal cavity as assessed 4 hours after carrageenin injection, and that this recruitment was most pronounced in AnxA1-null mice. In addition, this cell influx could be inhibited by the AnxA1 pharmacophore peptide, Ac2-26, in wild-type, AnxA1-null, and Fpr1-null mice, but was restored when co-treated with the pan-receptor antagonist Boc2. Using the LacZ gene reporter assay, an enhancement of AnxA1 gene promoter activity in extravasated neutrophils was evident in AnxA1-null mice; again this response was reduced after peptide treatment. The lack of functional involvement of Fpr1 prompted us to monitor the structurally related receptor Fpr2. We report, for the first time, the ultrastructural immunocytochemical co-localization of Fpr2 with AnxA1 in neutrophils that migrate into the mesenteric microcirculation and extravasate into the peritoneal fluid. Collectively, these data provide in vivo support to the hypothesis that endogenous AnxA1 is an essential effector of endogenous anti-inflammation and provide an ultrastructural indication that this mediator interacts with Fpr2 in murine neutrophils. We believe that these findings could significantly affect the development of novel therapeutics, which are modeled after the anti-migratory actions of AnxA1.

Skin peptides: biological activity and therapeutic opportunities

The skin provides an effective barrier to the loss of body fluids and environmental assault. In addition to the physical barrier provided by the stratum corneum, the skin also contains a chemical barrier consisting of antimicrobial peptides (AMPs), which control microbial growth on the surface. These AMPs also have multiple roles as mediators of inflammation with effects on epithelial and inflammatory cells, influencing cell proliferation, wound healing, cytokine/chemokine production and chemotaxis. This review describes the range of peptides found in the skin, both constitutive and those induced in response to injury. The role these peptides play in normal skin function and in various skin conditions is described. A better understanding of their role in normal and skin disease may offer new strategies in skin disease, dermatology and as cosmeceuticals.

Annexin 1 mediates the rapid anti-inflammatory effects of neutrophil-derived microparticles

Polymorphonuclear leukocyte (PMN)-derived microparticles display inhibitory properties on target cells as assessed in vitro; since PMNs contain abundant amounts of the endogenous anti-inflammatory protein annexin 1 (AnxA1), we tested here whether biologically active AnxA1 could be present in PMN-derived microparticles. PMN adhesion to human umbilical vein endothelial cell (HUVEC) monolayers led to the generation of microparticles that contained AnxA1, as detected by Western blotting, flow cytometry, and mass spectrometry analyses. Addition of these microparticles to recipient PMNs prior to flow over HUVEC monolayers significantly inhibited cell adhesion, an effect abrogated by a neutralizing anti-AnxA1 antibody, or an antibody raised against the AnxA1 receptor, that is termed lipoxin A(4) receptor or ALX. Intravenous delivery of human PMN-derived microparticles markedly inhibited PMN recruitment to an air pouch inflamed with IL-1beta. This anti-inflammatory effect was also dependent on endogenous AnxA1, since injection of microparticles produced from wild-type PMNs (bone marrow derived), but not from AnxA1-null PMNs, inhibited IL-1beta-induced leukocyte trafficking. In conclusion, PMN-derived microparticles contain functionally active AnxA1 that confers them anti-inflammatory properties; generation of these microparticles in the microcirculation could promote inflammatory resolution by time-dependent dampening of cell recruitment.

Human neutrophil-pulmonary microvascular endothelial cell interactions in vitro: differential effects of nitric oxide vs. peroxynitrite

Sepsis-induced acute lung injury is characterized by activation and injury of pulmonary microvascular endothelial cells (PMVEC), increased neutrophil-PMVEC adhesion and migration, and trans-PMVEC high-protein edema. Inducible NO synthase (iNOS) inhibits septic murine neutrophil migration in vivo and in vitro. The effects of NO in human neutrophil-PMVEC interactions are not known. We isolated human PMVEC using magnetic bead-bound anti-PECAM antibody. Confluent PMVEC at passage 3-4 were co-cultured with human neutrophils for assessment of neutrophil-PMVEC adhesion, and trans-PMVEC neutrophil migration and Evans-Blue dye-labeled albumin leak. Two NO donors (spermine-NONOate, S-nitroso-N-acetylpenicillamine) attenuated both cytomix-enhanced neutrophil-PMVEC adhesion by 64+/-14% (p<0.01) and 32+/-3% (p<0.05), respectively, and cytomix-induced trans-PMVEC neutrophil migration by 85+/-16% (p<0.01) and 43+/-5% (p<0.01), respectively. Correspondingly, iNOS inhibition with 1400W enhanced cytomix-stimulated neutrophil migration by 52+/-3% (p<0.01), but had no effect on neutrophil-PMVEC adhesion. Conversely, a peroxynitrite donor (SIN-1) increased both neutrophil-PMVEC adhesion (38+/-2% vs. 14+/-1% control, p<0.01) and trans-PMVEC neutrophil migration; with both effects were completely inhibited by scavenging of NO, superoxide, or peroxynitrite (p<0.05 for each). Scavenging of peroxynitrite also eliminated cytomix-induced neutrophil adhesion and migration. Blocking CD18-dependent neutrophil adhesion prevented cytomix-stimulated trans-PMVEC EB-albumin leak (p<0.05), while inhibiting neutrophil migration paradoxically enhanced cytomix-stimulated EB-albumin leak (11+/-1% vs. 7+/-0.5%, p<0.01). FMLP-induced neutrophil migration had no effect on trans-PMVEC EB-albumin leak. In summary, we report differential effects, including the inhibitory action of NO and stimulatory effect of ONOO(-) on human neutrophil-PMVEC adhesion and trans-PMVEC migration under cytomix stimulation. Moreover, neutrophil-PMVEC adhesion, but not trans-PMVEC migration, contributes to human PMVEC barrier dysfunction.

NKT cells inhibit the development of experimental crescentic glomerulonephritis

CD1d is an MHC class I-like, beta2-microglobulin-associated protein, constitutively expressed by antigen-presenting cells and some epithelial cells, which is recognized by NKT cells, a subpopulation of T cells. CD1d-dependent NKT cells confer protection in immune-mediated disorders, but whether these cells modulate the development of glomerulonephritis is unknown. Experimental crescentic glomerulonephritis was induced by administering anti-glomerular basement membrane antibodies to NKT cell-deficient (CD1d(-/-)) and wild-type mice. Compared with wild-type mice, NKT cell-deficient mice had an accelerated course of glomerulonephritis measured by renal function and crescent formation, and this was abrogated by adoptive transfer of NKT cells. Reconstitution with NKT cells also attenuated intraglomerular expression of TGF-beta1 and decreased phosphorylation of the transcription factors NF-kappaB and IkappaB. Adopted transfer of fluorescence-labeled NKT cells demonstrated their distribution to glomeruli damaged by anti-glomerular basement membrane antibodies but not to the tubulointerstitium. The chemokine CXCL16, which is the ligand for CXCR6 on NKT cells, was upregulated in glomeruli after induction of glomerulonephritis, and NKT cells were present in the same glomeruli. In vitro, NKT cells inhibited LPS-stimulated proliferation of mesangial cells, an affect that was reduced by co-current treatment with an anti-CXCL16 monoclonal antibody. In summary, these findings highlight the regulatory capacity of CD1d-dependent NKT cells in experimental glomerulonephritis and suggest that CXCL16 is involved in the recruitment of these cells to the site of injury.

Opposing regulation of neutrophil apoptosis through the formyl peptide receptor-like 1/lipoxin A4 receptor: implications for resolution of inflammation

Neutrophils have a central role in innate immunity, and their programmed cell death and removal are critical to the optimal expression as well as to efficient resolution of inflammation. Human neutrophils express the pleiotropic receptor formyl peptide receptor-like 1/lipoxin A4 (LXA(4)) receptor that binds a variety of ligands, including the acute-phase reactant serum amyloid A (SAA), the anti-inflammatory lipids LXA(4) and aspirin-triggered 15-epi-LXA(4) (ATL), and the glucocorticoid-inducible protein annexin 1. In addition to regulation of neutrophil activation and recruitment, these ligands have a profound influence on neutrophil survival and apoptosis with contrasting actions, mediating aggravation or resolution of the inflammatory response. Thus, annexin 1 accelerates, whereas SAA rescues human neutrophils from constitutive apoptosis by preventing mitochondrial dysfunction and subsequent activation of caspase-3. Furthermore, ATL overcomes the antiapoptosis signal from SAA and redirects neutrophils to caspase-mediated cell death. We review recent developments about the molecular basis of these actions and suggest a novel mechanism by which aspirin promotes resolution of acute inflammation and tissue injury.

Uteroglobin: a steroid-inducible immunomodulatory protein that founded the Secretoglobin superfamily

Blastokinin or uteroglobin (UG) is a steroid-inducible, evolutionarily conserved, secreted protein that has been extensively studied from the standpoint of its structure and molecular biology. However, the physiological function(s) of UG still remains elusive. Isolated from the uterus of rabbits during early pregnancy, UG is the founding member of a growing superfamily of proteins called Secretoglobin (Scgb). Numerous studies demonstrated that UG is a multifunctional protein with antiinflammatory/ immunomodulatory properties. It inhibits soluble phospholipase A(2) activity and binds and perhaps sequesters hydrophobic ligands such as progesterone, retinols, polychlorinated biphenyls, phospholipids, and prostaglandins. In addition to its antiinflammatory activities, UG manifests antichemotactic, antiallergic, antitumorigenic, and embryonic growth-stimulatory activities. The tissue-specific expression of the UG gene is regulated by several steroid hormones, although a nonsteroid hormone, prolactin, further augments its expression in the uterus. The mucosal epithelia of virtually all organs that communicate with the external environment express UG, and it is present in the blood, urine, and other body fluids. Although the physiological functions of this protein are still under investigation, a single nucleotide polymorphism in the UG gene appears to be associated with several inflammatory/autoimmune diseases. Investigations with UG-knockout mice revealed that the absence of this protein leads to phenotypes that suggest its critical homeostatic role(s) against oxidative damage, inflammation, autoimmunity, and cancer. Recent studies on UG-binding proteins (receptors) provide further insight into the multifunctional nature of this protein. Based on its antiinflammatory and antiallergic properties, UG is a potential drug target.

Interaction of antiflammin-1 with uteroglobin-binding protein induces phosphorylation of ERK1/2 in NIH 3T3 cells

Previously, it has been suggested that uteroglobin (UG)-binding protein functions as a putative receptor of UG; however, the specific epitope of UG that interacts with this receptor has not yet been identified. The downstream events of UG-binding protein signaling remain unclear. Here we report that antiflammin-1 (AF-1, a bioactive C-terminal peptide of UG) specifically binds to UG-binding protein and has a cellular signaling consequence. We reduced the level of endogenous UG-binding protein expression in murine fibroblast cell line NIH 3T3 by RNA interference and found that knockdown of UG-binding protein inhibited AF-1-induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation. Meanwhile, the interaction between AF-1 and UG-binding protein was confirmed by flow cytometry-based binding assays and co-localization of AF-1 and enhanced green fluorescent protein (EGFP)-tagged UG-binding protein. The present study provides evidence for the first time for AF-1 binding with UG-binding protein, and preliminarily characterized UG-binding protein as a point downstream of AF-1 in mediating ERK phosphorylation.

The metabolic changes caused by dexamethasone in the adjuvant-induced arthritic rat

The action of orally administered dexamethasone (0.2 mg kg(-1) day(-1)) on metabolic parameters of adjuvant-induced arthritic rats was investigated. The body weight gain and the progression of the disease were also monitored. Dexamethasone was very effective in suppressing the Freund's adjuvant-induced paw edema and the appearance of secondary lesions. In contrast, the body weight loss of dexamethasone-treated arthritic rats was more accentuated than that of untreated arthritic or normal rats treated with dexamethasone, indicating additive harmful effects. The perfused livers from dexamethasone-treated arthritic rats presented high content of glycogen in both fed and fasted conditions, as indicated by the higher rates of glucose release in the absence of exogenous substrate. The metabolization of exogenous L: -alanine was increased in livers from dexamethasone-treated arthritic rats in comparison with untreated arthritic rats, but there was a diversion of carbon flux from glucose to L: -lactate and pyruvate. Plasmatic levels of insulin and glucose were significantly higher in arthritic rats following dexamethasone administration. Most of these changes were also found in livers from normal rats treated with dexamethasone. The observed changes in L: -alanine metabolism and glycogen synthesis indicate that insulin was the dominant hormone in the regulation of the liver glucose metabolism even in the fasting condition. The prevalence of the metabolic effects of dexamethasone over those ones induced by the arthritis disease suggests that dexamethasone administration was able to suppress the mechanisms implicated in the development of the arthritis-induced hepatic metabolic changes. It seems thus plausible to assume that those factors responsible for the inflammatory responses in the paws and for the secondary lesions may be also implicated in the liver metabolic changes, but not in the body weight loss of arthritic rats.

Genetic analysis of CC16, OGG1 and GCLC polymorphisms and susceptibility to COPD

BACKGROUND AND OBJECTIVES

The importance of genetic susceptibility in COPD has not been determined. The aim of this study was to investigate the association between susceptibility to COPD and polymorphisms in the Clara cell 16 kDa secretory protein (CC16), 8-hydroxy-guanine glycosylase (OGG1) and glutamatecysteine ligase catalytic subunit (GCLC) genes in a southern Chinese population of Han nationality.

METHODS

A case-control study was performed on 166 paired subjects with or without COPD, who were randomly selected from a pool of 310 paired subjects. These subjects were selected from epidemiological survey participants, with matched-pairs being strictly localized in the Guangzhou urban and Shaoguan rural areas. The following polymorphisms were genotyped by PCR-single strand conformation polymorphism analysis: 38 A/G in exon 1 of the CC16 gene, 1245C/G in exon 7 of the OGG1 gene and -129C/T in the GCLC gene. Genotype frequencies and allelic frequencies were analysed.

RESULTS

There were no significant differences in the distribution of genotype frequencies for CC16 38 A/G, OGG1 1245C/G or GCLC -129C/T between the COPD and non-COPD subjects. The distribution of the allelic frequencies of these three genes also showed no significant difference between the two groups.

CONCLUSIONS

The genetic polymorphisms in CC16 38 A/G, OGG1 1245C/G and GCLC -129C/T are not associated with susceptibility to COPD in a southern Chinese population of Han nationality.

Antiflammin-2 activates the human formyl-peptide receptor like 1

The anti-inflammatory actions of the nonapeptide antiflammin-2, identified by homology with uteroglobin and annexin-A1 sequences, have been described in some detail, yet its mechanisms of action remain elusive. Since recent data indicate an involvement of the formyl peptide receptor (FPR)-like 1 (or FPRL-1) in the effects of annexin-A1, we have tested here the effect of antiflammin-2 with respect to this receptor family. Using HEK-293 cells expressing either human FPR and FPRL-1, and an annexin-A1 peptide as tracer ([¹²⁵I-Tyr]-Ac2-26), we found that antiflammin-2 competed for binding only at FPRL-1, and not FPR, with an approximate EC₅₀ of 1 μM. In line with data produced for the full-length protein, genuine receptor activation by antiflammin-2 was confirmed by rapid phosphorylation of extracellular-regulated kinase 1 and 2. Finally, study of the neutrophil interaction with activated endothelium under flow demonstrated an inhibitory effect of antiflammin-2, thus providing functional support to a role for the antiflammin-2/FPRL-1 anti-inflammatory axis.

Spatial and temporal profiles for anti-inflammatory gene expression in leukocytes during a resolving model of peritonitis

The recent appreciation of the role played by endogenous counterregulatory mechanisms in controlling the outcome of the host inflammatory response requires specific analysis of their spatial and temporal profiles. In this study, we have focused on the glucocorticoid-regulated anti-inflammatory mediator annexin 1. Induction of peritonitis in wild-type mice rapidly (4 h) produced the expected signs of inflammation, including marked activation of resident cells (e.g., mast cells), migration of blood-borne leukocytes, mirrored by blood neutrophilia. These changes subsided after 48-96 h. In annexin 1(null) mice, the peritonitis response was exaggerated ( approximately 40% at 4 h), with increased granulocyte migration and cytokine production. In blood leukocytes, annexin 1 gene expression was activated at 4, but not 24, h postzymosan, whereas protein levels were increased at both time points. Locally, endothelial and mast cell annexin 1 gene expression was not detectable in basal conditions, whereas it was switched on during the inflammatory response. The significance of annexin 1 system plasticity in the anti-inflammatory properties of dexamethasone was assessed. Clear induction of annexin 1 gene in response to dexamethasone treatment was evident in the circulating and migrated leukocytes, and in connective tissue mast cells; this was associated with the steroid failure to inhibit leukocyte trafficking, cytokine synthesis, and mast cell degranulation in the annexin 1(null) mouse. In conclusion, understanding how inflammation is brought under control will help clarify the complex interplay between pro- and anti-inflammatory pathways operating during the host response to injury and infection.

Effects of antiflammins on transglutaminase and phospholipase A2 activation by transglutaminase

Two anti-inflammatory peptides, named antiflammins (AFs), corresponding to a region with high amino acid similarity between lipocortin-1 and uteroglobin were tested for their ability to inhibit transglutaminase (TG) and low-molecular-mass phospholipase A2 (PLA2). Porcine pancreatic PLA2 activity and guinea pig hepatic TG activity were determined by arachidonyl release from arachidonyl-phosphatidylcholine and by the incorporation of putrescine into succinylated casein, respectively. AFs inhibited TG activity but did not affect PLA2 activity. Moreover, porcine pancreatic PLA2 was activated by TG and AFs decreased porcine pancreatic PLA2 activation induced by TG. Taken together, our results support the hypothesis that the anti-inflammatory effects of AFs are, at least in part, due to the action of AFs on TG activity.

Annexin 1 and its bioactive peptide inhibit neutrophil-endothelium interactions under flow: indication of distinct receptor involvement

We have tested the effects of annexin 1 (ANXA1) and its N-terminal peptide Ac2-26 on polymorphonuclear leukocyte (PMN) recruitment under flow. Differential effects of the full-length protein and its peptide were observed; ANXA1 inhibited firm adhesion of human PMNs, while Ac2-26 significantly attenuated capture and rolling without effect on firm adhesion. Analysis of the effects of ANXA1 and Ac2-26 on PMN adhesion molecule expression supported the flow chamber results, with Ac2-26 but not ANXA1 causing l-selectin and PSGL-1 shedding. ANXA1 and its peptide act via the FPR family of receptors. This was corroborated using HEK-293 cells transfected with FPR or FPRL-1/ALX (the 2 members of this family expressed by human PMNs). While Ac2-26 bound both FPR and FPRL-1/ALX, ANXA1 bound FPRL-1/ALX only. ANXA1 and Ac2-26 acted as genuine agonists; Ac2-26 binding led to ERK activation in both FPR- and FPRL-1/ALX-transfected cells, while ANXA1 caused ERK activation only in cells transfected with FPRL-1/ALX. Finally, blockade of FPRL-1/ALX with a neutralizing monoclonal antibody was found to abrogate the effects of ANXA1 in the flow chamber but was without effect on Ac2-26-mediated inhibition of rolling. These findings demonstrate for the first time distinct mechanisms of action for ANXA1 and its N-terminal peptide Ac2-26.

Critical protective role for annexin 1 gene expression in the endotoxemic murine microcirculation

The inflammatory response is a protective process of the body to counteract xenobiotic penetration and injury, although in disease this response can become deregulated. There are endogenous biochemical pathways that operate in the host to keep inflammation under control. Here we demonstrate that the counterregulator annexin 1 (AnxA1) is critical for controlling experimental endotoxemia. Lipopolysaccharide (LPS) markedly activated the AnxA1 gene in epithelial cells, neutrophils, and peritoneal, mesenteric, and alveolar macrophages--cell types known to function in experimental endotoxemia. Administration of LPS to AnxA1-deficient mice produced a toxic response characterized by organ injury and lethality within 48 hours, a phenotype rescued by exogenous application of low doses of the protein. In the absence of AnxA1, LPS generated a deregulated cellular and cytokine response with a marked degree of leukocyte adhesion in the microcirculation. Analysis of LPS receptor expression in AnxA1-null macrophages indicated an aberrant expression of Toll-like receptor 4. In conclusion, this study has detailed cellular and biochemical alterations associated with AnxA1 gene deletion and highlighted the impact of this protective circuit for the correct functioning of the homeostatic response to sublethal doses of LPS.

Annexin 1-deficient neutrophils exhibit enhanced transmigration in vivo and increased responsiveness in vitro

The role of the endogenous anti-inflammatory mediator annexin 1 (AnxA1) in controlling polymorphonuclear leukocyte (PMN) trafficking and activation was addressed using the recently generated AnxA1 null mouse. In the zymosan peritonitis model, AnxA1 null mice displayed a higher degree (50-70%) of PMN recruitment compared with wild-type littermate mice, and this was associated with reduced numbers of F4/80+ cells. Intravital microscopy analysis of the cremaster microcirculation inflamed by zymosan (6 h time-point) indicated a greater extent of leukocyte emigration, but not rolling or adhesion, in AnxA1 null mice. Real-time analysis of the cremaster microcirculation did not show spontaneous activation in the absence of AnxA1; however, superfusion with a direct-acting PMN activator (1 nM platelet-activating factor) revealed a subtle yet significant increase in leukocyte emigration, but not rolling or adhesion, in this genotype. Changes in the microcirculation were not secondary to alterations in hemodynamic parameters. The phenotype of the AnxA1 null PMN was investigated in two in vitro assays of cell activation (CD11b membrane expression and chemotaxis): the data obtained indicated a higher degree of cellular responses irrespective of the stimulus used. In conclusion, we have used a combination of inflammatory protocols and in vitro assays to address the specific counter-regulatory role of endogenous AnxA1, demonstrating its inhibitory control on PMN activation and the consequent impact on the inflamed microcirculation.

An overview of the effects of annexin 1 on cells involved in the inflammatory process

The concept of anti-inflammation is currently evolving with the definition of several endogenous inhibitory circuits that are important in the control of the host inflammatory response. Here we focus on one of these pathways, the annexin 1 (ANXA1) system. Originally identified as a 37 kDa glucocorticoid-inducible protein, ANXA1 has emerged over the last decade as an important endogenous modulator of inflammation. We review the pharmacological effects of ANXA1 on cell types involved in inflammation, from blood-borne leukocytes to resident cells. This review reveals that there is scope for more research, since most of the studies have so far focused on the effects of the protein and its peptido-mimetics on neutrophil recruitment and activation. However, many other cells central to inflammation, e.g. endothelial cells or mast cells, also express ANXA1: it is foreseen that a better definition of the role(s) of the endogenous protein in these cells will open the way to further pharmacological studies. We propose that a more systematic analysis of ANXA1 physio-pharmacology in cells involved in the host inflammatory reaction could aid in the design of novel anti-inflammatory therapeutics based on this endogenous mediator.

Recombinant uteroglobin prevents the experimental crescentic glomerulonephritis

BACKGROUND

Although uteroglobin is known to have an immunomodulatory property and prevents the deposition of immune-complexes on the glomeruli of mice, the therapeutic potential of uteroglobin is uncertain in glomerulonephritis. To test the hypothesis that uteroglobin can prevent glomerulonephritis, we have studied the effects of recombinant uteroglobin on the development of experimental crescentic glomerulonephritis that is induced by anti-glomerular basement membrane (anti-GBM) antibodies.

METHODS AND RESULTS

Glomerulonephritis was induced by the intravenous injection of rabbit anti-GBM globulin antibodies into mice (C57BL/6), and renal injury was evaluated 7, 14, and 21 days afterward. Recombinant uteroglobin or phosphate-buffered saline (PBS) were given intravenously to mice for 3 days after anti-GBM antibody injection. Proteinuria was significantly reduced in mice treated with recombinant uteroglobin compared with disease-control mice at 7 and 14 days after an anti-GBM antibody injection, although the serum creatinine concentration was similar in both groups. The amount of proteinuria was similar in recombinant uteroglobin-treated and normal control mice. By histologic analysis, mesangial matrix expansion, mesangial proliferation, and cellular crescents representing crescentic glomerulonephritis were markedly attenuated by injection of recombinant uteroglobin. The in vitro proliferative responses of mesangial cells to lipopolysaccharide (LPS) were blunted by the addition of recombinant uteroglobin in a dose-dependent manner. The preventive effects exerted by recombinant uteroglobin treatment were based on the inhibition of antibodies and complement-3 deposition on the glomeruli.

CONCLUSION

This study demonstrates the preventive effects of recombinant uteroglobin in an experimental model of crescentic glomerulonephritis, and suggests the therapeutic implications of uteroglobin for human chronic glomerulonephritis.

The annexin 1 receptor(s): is the plot unravelling?

Recent studies have proposed a functional link between annexin 1 (ANXA1), an endogenous anti-inflammatory mediator, and receptors of the formyl-peptide family. In particular, exogenous and endogenous ANXA1 and its peptidomimetics interact with one member of this family, the formyl-peptide-receptor-like 1. Further analyses of the interactions between ANXA1 and this and other members of this receptor family, and a better characterization of the ANXA1 receptor systems in models of inflammation, might clarify their mechanism of anti-inflammatory effects. This line of research will facilitate the development of ANXA1 mimetics and take advantage of >20 years of biological research into the functions of this glucocorticoid-modulated protein.

Annexin 1 and the biology of the neutrophil

This overview will focus on one aspect of neutrophil biology, which is the selective activation of the annexin 1 system in relation to the process of cell extravasation. Besides the current view about the biochemistry of annexin 1 and annexin 1 receptor(s) up-regulation within the microenvironment of the adherent neutrophils, we will also comment on the final result achieved by activation of the system, which is inhibition of neutrophil recruitment. In view of the historical link between annexin 1 and glucocorticoids, the potential for the annexin 1 system in mediating at least some of the anti-inflammatory actions of these powerful drugs is also discussed.

A novel calcium-dependent proapoptotic effect of annexin 1 on human neutrophils

The glucocorticoid-inducible protein annexin (ANXA) 1 is an anti-inflammatory mediator that down-regulates the host response. Endogenously, ANXA1 is released in large amounts from adherent polymorphonuclear neutrophils (PMN) and binds to their cell surface to inhibit their extravasation into inflamed tissues. The present study determined the effects of exogenous ANXA1 on several functions of human PMN in vitro. Addition of 0.1-1 microM human recombinant ANXA1 to the PMN provoked rapid and transient changes in intracellular Ca2+ concentrations that were blocked by the Ca2+ channel inhibitor SKF-96365. Although ANXA1 did not affect oxidant production and only minimally affected PMN chemotactic properties, the ANXA1-promoted Ca2+ influx was associated with two important functional effects: shedding of L-selectin and acceleration of PMN apoptosis. The latter effect was confirmed using three distinct technical procedures, namely, cell cycle, Hoechst staining, and ANXA5 binding assay. ANXA1-induced PMN apoptosis was insensitive to inhibitors of L-selectin shedding, whereas it appeared to be associated with dephosphorylation of the proapoptotic intracellular mediator BAD. In conclusion, exogenous ANXA1 displayed selective actions on human PMN. We propose that the new proapoptotic effect reported here may be part of the spectrum of ANXA1-mediated events involved in the resolution of acute inflammation.

Novel transglutaminase inhibitors reverse the inflammation of allergic conjunctivitis

Steroidal anti-inflammatory drugs induce proteins that inhibit phospholipase A(2) (PLA(2)), including uteroglobin and lipocortin-1 (annexin I). Uteroglobin and lipocortin-1 retain several conserved sequences. Based on these sequences, several nonapeptides (antiflammins) were synthesized. These nonapeptides were shown to have anti-inflammatory effects in vitro and in vivo, possibly by inhibiting PLA(2). Subsequent research showed that PLA(2) is activated by transglutaminase 2 (TGase 2). We hypothesize here that TGase 2 inhibitors may increase the anti-inflammatory efficacy of inhibiting PLA(2) activity. To test this theory, we constructed recombinant peptides containing sequences from pro-elafin (for inhibition of TGase 2), and from lipocortin-1, lipocortin-5, and uteroglobin (for inhibition of PLA(2)). The recombinant peptides, which had dual inhibitory effects on purified TGase 2 and PLA(2), reversed the inflammation of allergic conjunctivitis to ragweed in a guinea pig model. The present work suggests that novel recombinant peptides may be safe and effective agents for the treatment of various inflammatory diseases.