A Proinflammatory Role for Proteolytically Cleaved Annexin A1 in Neutrophil Transendothelial Migration

Abstract

Neutrophil extravasation, a critical component of innate immunity must be tightly regulated to prevent inadvertent or prolonged inflammation and subsequent tissue damage. We have shown previously that endothelial ERK1/2 signaling essential for neutrophil transendothelial migration is induced by a soluble factor produced by activated neutrophils. In this study, we demonstrate that the soluble neutrophil factor is a truncated form of annexin A1 (AnxA1) that can be generated by calpain 1 cleavage of the N terminus, thus identifying a novel proinflammatory function to AnxA1. In contrast, neither the full-length protein nor the N-terminal 26 aa peptide, previously shown to be antiinflammatory, were able to activate Erk. Our data suggest that two different fragments of AnxA1 have opposing functions in inflammation. We also provide evidence that C-terminal AnxA1 functions by increasing ICAM1 clustering around adherent neutrophils to anchor them to the endothelium and promote transmigration through the transcellular route.

Proresolving Actions of Synthetic and Natural Protease Inhibitors Are Mediated by Annexin A1

“…Thus, modulation of endogenous AnxA1 pool might be an important mechanism to resolve inflammatory responses. This can be even of more acute importance because the 33-kDa form of AnxA1 displays proinflammatory effects by promoting ERK1/2 activation and neutrophil transendothelial migration (16). To our knowledge, the first concept that the 33-kDa AnxA1 form might have proinflammatory properties has been suggested by findings in fluid samples from cystic fibrosis patients (15).…”

“…However, within this microenvironment AnxA1 is vulnerable to be cleaved at the N-terminal region by proteases including NE and PR3, generating the 33-kDa isoform of poorly known properties (13,14). Studies have shown that the 33-kDa isoform of AnxA1 may be associated with proinflammatory effects (15,16). Congruently, cleavage-resistant (CR) AnxA1 exhibited greater anti-inflammatory effect compared with the parent protein, in different animal models of inflammation (17,18).…”

Regulation of Cytosolic Phospholipase A2 Phosphorylation by Proteolytic Cleavage of Annexin A1 in Activated Mast Cells

“…ANXA1 cleavage promotes neutrophil transendothelial migration (17) and regulates EGF-triggered signaling and AA production in normal and malignant squamous epithelial cells (14). Recently, an ANXA1 mutant (A11R/V22K/V36K) was reported to be resistant to cleavage by all proteases present in PMN cell extracts (18).…”

“…The N-terminal peptide is known to be cleaved by a number of proteases, including elastase, calpain, plasmin, cathepsin D, and proteinase 3 (11)(12)(13)(14), and is also phosphorylated to regulate the activity of the protein (15,16). N-terminal truncated ANXA1 has a proinflammatory effect and promotes neutrophil transendothelial migration (17). Truncated ANXA1 has also been linked to an epidermal growth factor (EGF)-triggered signaling pathway involving cytosolic phospholipase A 2 (cPLA 2 ) in normal and malignant squamous epithelial cells (14).…”

A fragmented form of annexin A1 is secreted from C2C12 myotubes by electric pulse-induced contraction

“…ANXA1 has been identified in various cell types, where it is thought to be important in biological functions. Originally described as having an anti-inflammatory effect similar to that of glucocorticoids, ANXA1 has been demonstrated to be involved in various cellular processes, including inflammation [1], leukocyte migration [2], cell growth [3], and differentiation [4]. As ANXA1 does not have signal peptide sequences, it is thought to be secreted unconventionally [5].…”