Intracellular Interleukin-1 Receptor 2 Binding Prevents Cleavage and Activity of Interleukin-1α, Controlling Necrosis-Induced Sterile Inflammation

“The ‘‘danger’’ model proposes that immunity responds to nonphysiological cell death, damage, or stress (Matzinger, 1994).”

“Indeed, increased IL-1 activity is a hallmark of many chronic inflammatory conditions, including rheumatoid arthritis, gout, diabetes, atherosclerosis, and psoriasis (Dinarello, 1996, 2009; Duewell et al., 2010; Rajamäki et al., 2010).”

“Indeed, increased IL-1 activity is a hallmark of many chronic inflammatory conditions, including rheumatoid arthritis, gout, diabetes, atherosclerosis, and psoriasis (Dinarello, 1996, 2009; Duewell et al., 2010; Rajamäki et al., 2010).”

“IL-1a is near universally expressed (Dinarello, 2009), lacks a signal peptide, is rarely extracellular under normal physiology, and also associates with chromatin during apoptosis, resulting in retention (Cohen et al.”

“Many human diseases are driven by activation of these pathways, including ischemia-reperfusion injury, Alzheimer’s disease, atherosclerosis, and toxic insults to liver and lung (Chen and Nuñez, 2010; Kono and Rock, 2008; Stewart et al., 2010).”

“Induction of antitumor immunity in vivo is dependent upon the mode of cell death, whereby necrosis is more immunogenic than apoptosis (Melcher et al., 1998) and local IL-1 activity (Ghiringhelli et al., 2009; Michaud et al., 2011).”

“Many human diseases are driven by activation of these pathways, including ischemia-reperfusion injury, Alzheimer’s disease, atherosclerosis, and toxic insults to liver and lung (Chen and Nuñez, 2010; Kono and Rock, 2008; Stewart et al., 2010).”

“Indeed, expression of an uncleavable IL-1R2 mutant reduces IL-1a release, whereas Casp1 / mice have long been known to be deficient in IL-1a secretion (Kuida et al., 1995; Li et al., 1995).”

“, 2003), and cytokine activity is supposedly independent of cleavage (March et al., 1985; Mosley et al., 1987).”

“Many human diseases are driven by activation of these pathways, including ischemia-reperfusion injury, Alzheimer’s disease, atherosclerosis, and toxic insults to liver and lung (Chen and Nuñez, 2010; Kono and Rock, 2008; Stewart et al., 2010).”

“IL-1a also has powerful effects on adaptive immunity by enhancing expansion and survival of T cells, differentiation of T helper 17 (Th17) cells, and effector T cell proliferation in the presence of regulatory T cells (Sims and Smith, 2010).”

“Induction of antitumor immunity in vivo is dependent upon the mode of cell death, whereby necrosis is more immunogenic than apoptosis (Melcher et al., 1998) and local IL-1 activity (Ghiringhelli et al., 2009; Michaud et al., 2011).”

“DAMPs are retained in healthy cells and during apoptosis (Basu et al., 2000; Cohenetal., 2010;Scaffidi etal., 2002),whereasnecrosis releases them into the extracellular milieu.”

“Indeed, increased IL-1 activity is a hallmark of many chronic inflammatory conditions, including rheumatoid arthritis, gout, diabetes, atherosclerosis, and psoriasis (Dinarello, 1996, 2009; Duewell et al., 2010; Rajamäki et al., 2010).”

“receptor that limits bioavailability of IL-1 (Colotta et al., 1993), we examined whether IL-1R2 silencing had reversed ‘‘general’’ IL-1 antagonism within necrotic lysates.”

“Interestingly, calpain is activated upon loss of plasma membrane integrity (Wang, 2000), suggesting that calpain cleavageof IL-1a could be a control point for activity postnecrosis.”

“, 2007, 2008), toxic liver insults (Chen et al., 2007), and ischemiareperfusion injury (Cohen et al.”

“Accordingly, necrotic death releases damage-associated molecular patterns (DAMPs), which are sensed as danger and act as universal signals to activate immunity (Chen and Nuñez, 2010; Kono and Rock, 2008; Rock et al., 2010).”

“, 2012) requires inflammasome activation, but given that IL-1a is not a caspase substrate, this has been puzzling (Keller et al., 2008).”

“In contrast, IL-33 processing by caspase-3 or caspase-1 results in inactivation (Cayrol andGirard, 2009; Lüthi et al., 2009).”

“…Clarke et al., 2010; Cohen et al., 2010; Eigenbrod et al., 2008;Konoet al., 2010;Raoet al., 2007), drivingpathologies as diverse as tumorigenesis (Sakurai et al., 2008), atherosclerosis (Clarke et al., 2010; Kamari et al., 2007), graft rejection (Rao et al., 2007, 2008), toxic liver insults…”

“, 2011) or dendritic cells (DCs) (Gross et al., 2012) requires inflammasome activation, but given that IL-1a is not a caspase substrate, this has been puzzling (Keller et al.”

“Induction of antitumor immunity in vivo is dependent upon the mode of cell death, whereby necrosis is more immunogenic than apoptosis (Melcher et al., 1998) and local IL-1 activity (Ghiringhelli et al., 2009; Michaud et al., 2011).”

“, 2003), and cytokine activity is supposedly independent of cleavage (March et al., 1985; Mosley et al., 1987).”

“IL-1a is near universally expressed (Dinarello, 2009), lacks a signal peptide, is rarely extracellular under normal physiology, and also associates with chromatin during apoptosis, resulting in retention (Cohen et al., 2010).”

“Pro-IL-1a (p33) is processed tomature IL-1a (p17) by calpain (Kobayashi et al., 1990), but the biological consequences of cleavage are unknown given that p33 is reported to be fully active.”

“Although a recent study reports increased IL-1a activity after granzyme B cleavage (Afonina et al., 2011), differential efficacy of p33 and p17 IL-1a is still controversial (Gross et al., 2012), and no mechanism to explain this has been reported.”

“, 2010), although recent work casts doubt on IL-1b’s role (Menu et al., 2011), suggesting that IL-1a could be the major ligand affecting atherosclerotic plaques.”

“Interleukin-1a (IL-1a) is an important DAMP that activates immunity postnecrosis (Chen et al., 2007; Clarke et al., 2010; Cohen et al., 2010; Eigenbrod et al., 2008;Konoet al., 2010;Raoet al., 2007), drivingpathologies as diverse as tumorigenesis (Sakurai et al., 2008), atherosclerosis (Clarke et…”

“…Eigenbrod et al., 2008;Konoet al., 2010;Raoet al., 2007), drivingpathologies as diverse as tumorigenesis (Sakurai et al., 2008), atherosclerosis (Clarke et al., 2010; Kamari et al., 2007), graft rejection (Rao et al., 2007, 2008), toxic liver insults (Chen et al., 2007), and ischemiareperfusion…”

“Several reports indicate that processing is not required for secretion (Brough et al., 2003; Prudovsky et al., 2003), and cytokine activity is supposedly independent of cleavage (March et al.”

“Finally, atherosclerosis is highly dependent on IL-1 (Chamberlain et al., 2009; Chi et al., 2004; Duewell et al., 2010), although recent work casts doubt on IL-1b’s role (Menu et al., 2011), suggesting that IL-1a could be the major ligand affecting atherosclerotic plaques.”

“Because recent work demonstrates that IL-1a secretion requires inflammasome activation (Fettelschoss et al., 2011), we investigated whether this could overcome IL-1R2 blockade.”

“Human monocyte-derived macrophages were differentiated as described previously (Brown et al., 2000).”

“Several reports indicate that processing is not required for secretion (Brough et al., 2003; Prudovsky et al., 2003), and cytokine activity is supposedly independent of cleavage (March et al.”

“The crystal structure of IL-1R2 complexed to IL-1 (Wang et al., 2010) revealed that cleavage at these sites would remove the D1 domain vital for binding.”

“The prototypic IL-1 family is ancient, with homologs identified back to echinoderms (Beck and Habicht, 1986).”

“Indeed, multiple factors determine how much of a signal peptide-containing protein ends up nontargeted, including the signal peptide and flanking amino acid sequences and cell type and growth condition effects (Levine et al., 2005).”

“Finally, atherosclerosis is highly dependent on IL-1 (Chamberlain et al., 2009; Chi et al., 2004; Duewell et al., 2010), although recent work casts doubt on IL-1b’s role (Menu et al.”

“Therefore we determined whether cell surface-shed IL-1R2 (Orlando et al., 1997) protects IL-1a by inhibiting metalloproteases with BB-94; p33, however, remained uncleaved (Figure S4B).”

“, 2008), atherosclerosis (Clarke et al., 2010; Kamari et al., 2007), graft rejection (Rao et al.”

“Previous studies concluded that IL-1a is only a secondary signaling molecule released by macrophages during sterile inflammation (Chen et al., 2007; Kono et al., 2010).”

“…2007), drivingpathologies as diverse as tumorigenesis (Sakurai et al., 2008), atherosclerosis (Clarke et al., 2010; Kamari et al., 2007), graft rejection (Rao et al., 2007, 2008), toxic liver insults (Chen et al., 2007), and ischemiareperfusion injury (Cohen et al., 2010; Luheshi et al., 2011).”

“Although the previously described splice variant of IL-1R2 (Liu et al., 1996) loses the transmembrane domain, it still codes for a signal peptide and should be secreted.”

“…2007), drivingpathologies as diverse as tumorigenesis (Sakurai et al., 2008), atherosclerosis (Clarke et al., 2010; Kamari et al., 2007), graft rejection (Rao et al., 2007, 2008), toxic liver insults (Chen et al., 2007), and ischemiareperfusion injury (Cohen et al., 2010; Luheshi et al., 2011).”

“790), and many proteins with signal peptides can be found in the cytosol (Davis et al., 2006).”

“Intriguingly, IL-1R2 is upregulated in some tumors including pancreatic ductal adenocarcinoma (Rückert et al., 2010) and ovarian cancer, where it provides a powerful distinction between primary and recurrent tumors (Laios et al.”

“, 2010) and ovarian cancer, where it provides a powerful distinction between primary and recurrent tumors (Laios et al., 2008).”

“Although we could express and purify p17 in E. coli, p33 was very insoluble and prone to aggregation (not shown)—a finding reported by others (Tokunaga et al., 2010).”

“Because IL-1R2 is expressed by a limited set of cells, this would represent a further mechanism of negative control of IL-1a by IL-1R2 during necrosis, restricted to specific cell types (Zheng et al., 2013).”