The annexin superfamily consists of 13 calcium or calcium and phospholipid binding proteins with a significant degree of biological and structural homology (40-60%). First described in the late 1970s and subsequently referred to as macrocortin, renocortin, lipomodulin, lipocortin-1, and more recently Annexin 1, this 37 kDa calcium and phospholipid binding protein is a strong inhibitor of glucocorticoid-induced eicosanoid synthesis and PLA2. Recent interest in the biological activity of this intriguing molecule has unraveled important functional attributes of Annexin 1 in a variety of inflammatory pathways, on cell proliferation machinery, in the regulation of cell death signaling, in phagocytic clearance of apoptosing cells, and most importantly in the process of carcinogenesis. Here we attempt to present a short review on these diverse biological activities of an interesting and important molecule, which could be a potential target for novel therapeutic intervention in a host of disease states.

Twenty-eight subjects meeting Diagnostic and Statistical Manual of Mental Disorders (rev. 3rd ed.; American Psychiatric Association, 1987) criteria for social phobia and without a comorbid affective disorder and 33 nonclinical controls were asked to present a brief, impromptu speech to a small audience. Speakers themselves, as well as members of the audience, rated each speaker on a public speaking questionnaire that included both specific items (e.g., voice shook) and global items (e.g., appeared confident). For global items, no significant difference was indicated between the two groups on observers' ratings of public speaking performance. However, social phobics rated their own performance worse than did nonclinical controls, and there was a significantly greater discrepancy between self and other ratings for social phobics than controls. Fear of negative evaluation was the only significant predictor of the self-other discrepancy on global items.

After injury or infection, neutrophils rapidly migrate from the circulation into tissues by means of an orderly progression of adhesion receptor engagements. Neutrophils have been previously considered to use selectins exclusively to roll on vessels before an adhesion step mediated by the β2 integrins, lymphocyte function–associated antigen (LFA)-1, and Mac-1. Here we use LFA-1−/− mice, function blocking monoclonal antibodies, and intravital microscopy to investigate the roles of LFA-1, Mac-1, and α4 integrins in neutrophil recruitment in vivo. For the first time, we show that LFA-1 makes a contribution to neutrophil rolling by stabilizing the transient attachment or tethering phase of rolling. In contrast, Mac-1 does not appear to be important for either rolling or firm adhesion, but instead contributes to emigration from the vessel. Blocking Mac-1 in the presence of LFA-1 significantly reduces emigration, suggesting cooperation between these two integrins. Low levels of α4β1 integrin can be detected on neutrophils from LFA-1+/+ and −/− mice. These cells make use of α4β1 during the rolling phase, particularly in the absence of LFA-1. Thus LFA-1 and α4β1, together with the selectins, are involved in the rolling phase of neutrophil recruitment, and, in turn, affect the later stages of the transmigration event.

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In this study we investigated, using intravital microscopy, how neutrophil extravasation across mouse mesenteric postcapillary venules is inhibited by the glucocorticoid-regulated protein lipocortin (LC; also termed annexin) 1. Intraperitoneal injection of 1 mg of zymosan into mice induced neutrophil rolling on the activated mesenteric endothelium followed by adhesion (maximal at 2 hr: 5-6 cells per 100-m of vessel length) and emigration (maximal at 4 hr: 8-10 cells per high-powered field). Treatment of mice with human recombinant LC1 (2 mg͞kg s.c.) or its mimetic peptide Ac2-26 (13 mg͞kg s.c.) did not modify cell rolling but markedly reduced (>50%) the degree of neutrophil adhesion and emigration (P < 0.05). Intravenous treatment with peptide Ac2-26 (13 mg͞kg) or recombinant human LC1 (0.7-2 mg͞kg) promoted detachment of neutrophils adherent to the endothelium 2 hr after zymosan administration, with adherent cells detaching within 4.12 ؎ 0.75 min and 2.36 ؎ 0.31 min, respectively (n ‫؍‬ 20-25 cells). Recruitment of newly adherent cells to the endothelium was unaffected. The structurally related protein LC5 was inactive in this assay, whereas a chimeric molecule constructed from the N terminus of LC1 (49 aa) attached to the core region of LC5 produced cell detachment with kinetics similar to LC1. Removal of adherent neutrophils from activated postcapillary endothelium is a novel pharmacological action, and it is at this site where LC1 and its mimetics operate to down-regulate this aspect of the host inf lammatory response.

The molecular mechanisms underlying constitutive nuclear factor-jB (NF-jB) activation in solid tumors has not been elucidated. We show that Annexin-1 (ANXA1) is involved in this process, and suppression of ANXA1 in highly metastatic breast cancer cells impedes migration and metastasis capabilities in vitro and in vivo. ANXA1 expression correlates with NF-jB activity, suggesting that ANXA1 may be required for the constitutive activity of IjB kinase (IKK) and NF-jB in highly metatstatic breast cancer. Gel-filtration analysis demonstrated that ANXA1 co-elutes with the members of the IKK complex and NF-jB signaling pathway, and immunoprecipitation confirmed that ANXA1 can bind to and interact with IKKc or NEMO, but not IKKa or IKKb. Importantly, silencing of ANXA1 prevents the interaction of NEMO and RIP1, which indicates that ANXA1 is required for the recruitment of RIP1 to the IKK complex, which may be important for the activation of NF-jB. Downstream targets of NF-jB include uPA and CXCR4, which can be modulated by ANXA1 silencing. CXCR4-mediated migration of breast cancer cell lines in response to CXCL12 was significantly modulated by ANXA1, indicating its importance in the tissue-specific migration of breast cancer cells. Chromatin immunoprecipitation experiments confirmed that in ANXA1 overexpressed cells, NF-jB was recruited to CXCR4 promoter without external stimulation, indicating that ANXA1 is critical for the constitutive activation of NF-jB in breast cancer to promote metastasis. Finally, we show that ANXA1 overexpression enhances metastasis and reduces survival in an intracardiac metastasis model, while ANXA1-deficient mice crossed with MMTV-PyMT mice display significantly less metastasis than their heterozygous littermates, indicating that ANXA1 is an important gene in breast cancer metastasis. Our data reveal that ANXA1 can constitutively activate NF-jB in breast cancer cells through the interaction with the IKK complex, and suggests that modulating ANXA1 levels has therapeutic potential to suppress breast cancer metastasis.

A cytotoxic cycle triggered by DNA single-strand breakage and poly (ADP-ribose) synthetase activation has been shown to contribute to the cellular injury during various forms of oxidant stress in vitro. The aim of this study was to investigate the role of poly (ADP-ribose) synthetase (PARS) in the process of neutrophil recruitment and in development of local and systemic inflammation. In pharmacological studies, PARS was inhibited by 3-aminobenzamide (10–20 mg/kg) in rats and mice. In other sets of studies, inflammatory responses in PARS−/− mice were compared with the responses in corresponding wild-type controls. Inhibition of PARS reduced neutrophil recruitment and reduced the extent of edema in zymosan- and carrageenan-triggered models of local inflammation. Moreover, inhibition of PARS prevented neutrophil recruitment, and reduced organ injury in rodent models of inflammation and multiple organ failure elicited by intraperitoneal injection of zymosan. Inhibition of PARS also reduced the extent of neutrophil emigration across murine mesenteric postcapillary venules. This reduction was due to an increased rate of adherent neutrophil detachment from the endothelium, promoting their reentry into the circulation. Taken together, our results demonstrate that PARS inhibition reduces local and systemic inflammation. Part of the antiinflammatory effects of PARS inhibition is due to reduced neutrophil recruitment, which may be related to maintained endothelial integrity.

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