Objective The purpose of this study was to establish a reliable, chronic model of abdominal aortic aneurysm (AAA). Materials and methods 120 eight-week old C56BL/6 male mice were equally divided into three groups: 1) BAPN Group: 0.2% 3-aminopropionitrile fumarate salt (BAPN) drinking water was provided to mice two days before surgery until the end of study. Sham aneurysm induction surgery was performed using 5 μl of heat de-activated elastase. 2) Elastase Group: Mice were given regular drinking water without BAPN. During aneurysm induction surgery, 5 μl of active form elastase (10.3mg protein/ml, 5.9units/mg protein) was applied on top of adventitia of infrarenal abdominal aorta for 5 minutes. 3) BAPN+Elastase Group: Mice were given both BAPN drinking water and active form of elastase application as above. On post-operative days 7, 14, 21, 28 and 100, aortic samples were collected for histology, cytokine array and gelatin zymography after aortic diameter measurement. Results Compared with Elastase group, BAPN+Elastase group had higher AAA formation rate (93% vs 65%, P < .01) with more advanced-staged AAAs (25/42 vs 1/40 for Stage II & III, P < .001). Aneurysms from the BAPN+Elastase Group demonstrated persistent long-term growth (221.5 ± 36.6%, 285.8 ± 78.6%, 801 ± 160% on day 21, 28 and 100 respectively, P ˂ .001), with considerable thrombus formation (54%) and rupture (31%) at the advanced stages of AAA development. Cytokine levels (pro-MMP9, IL-1β, IL-6, CCL-5, TREM-1, MCP-1 and TIMP-1) in BAPN+Elastase Group were higher than Elastase Group on day 7. After day 7, cytokine levels returned to baseline with the exception of elevated MMP2 activity. By histology, CD3⁺T cells in the BAPN+Elastase Group were elevated on days 28 and 100. Conclusions A combination of oral BAPN administration and peri-aortic elastase application induced a chronic, advanced staged AAA with characteristics of persistent aneurysm growth, thrombus formation, and spontaneous rupture. Future studies should utilize this model, especially for examining tissue remodeling during the late stages of aneurysm development.

The degradation of misfolded proteins is essential for cellular and organism viability. Quality control mechanisms of protein folding involve multi-component systems, which include chaperones, ubiquitylation enzymes, and ultimately degradation by the proteasome. So far, quality control mechanisms have been described in the cytoplasm, the nucleus and endoplasmic reticulum (ER) (Bader et al., 2007;Goldberg, 2003;Hampton, 2002;Jarosch et al., 2003;Meusser et al., 2005;von Mikecz, 2006).The recognition and degradation of misfolded proteins in the ER is called ER-associated degradation (ERAD) (Hampton, 2002;Jarosch et al., 2003;McCracken and Brodsky, 2003;Meusser et al., 2005;Richly et al., 2005;Sitia and Braakman, 2003). Membrane-spanning and secretory proteins are first transported into the ER in an unfolded state through the Sec61p complex (Matlack et al., 1998). Folding of these nascent polypeptides is assisted by a number of ER-resident chaperones. Translocated proteins also undergo modifications to support folding; these include N-terminal glycosylation and disulphide bond formation (Meusser et al., 2005;Schroder and Kaufman, 2005;Sitia and Braakman, 2003). In the ER, proteins that do not fold properly are retro-translocated to the cytoplasm. During retro-translocation, these misfolded proteins are ubiquitylated by several ER-specific E3 ubiquitin ligase complexes. A cytoplasmic ubiquitin-binding and multi-ubiquitylation enzyme complex further modifies these proteins and finally transports them to the proteasome for degradation.The accumulation of misfolded proteins in the ER activates the unfolded protein response (UPR), which is required for cells to survive conditions of stress. The UPR is mediated by three ER transmembrane proteins, IRE1, PERK and ATF6, which get activated at least in part because of the dissociation of the ER chaperone BiP, to which they are normally bound and also because of their sequestration by misfolded proteins (Bertolotti et al., 2000;Cox et al., 1993;Harding et al., 1999;Haze et al., 1999;Iwawaki et al., 2001;Kimata et al., 2004;Lee et al., 2002;Mori et al., 1993;Okamura et al., 2000). IRE1, PERK and ATF6 function to decrease the load on the ER by reducing translation rate and activating the transcription of chaperones, ERAD proteins and other enzymes. UPR activation also results in increased biosynthesis of some lipids, the elaboration of the ER and increased secretion (Sato et al., 2002;Shaffer et al., 2004;Sriburi et al., 2004). A major downstream regulator of UPR is XBP1/HAC1. Upon activation of IRE1, the XBP1 mRNA is directly spliced by an endonuclease activity in the C-terminus of IRE-1; this splice variant of XBP1 functions as a potent transcriptional activator of several genes (Calfon et al., 2002;Cox and Walter, 1996;Sidrauski and Walter, 1997;Yoshida et al., 2001).Derlin proteins are a conserved family that function in ERAD (Schekman, 2004). They have four transmembrane domains and are conserved in all eukaryotes. There are two members in Saccharomyces cerevisiae, Der1p a...

Ligand-gated ion channels are transmembrane proteins that respond to a variety of transmitters, including acetylcholine, gamma-aminobutyric acid (GABA), glycine, and glutamate [1 and 2]. These proteins play key roles in neurotransmission and are typically found in the nervous system and at neuromuscular junctions [3]. Recently, acetylcholine receptor family members also have been found in nonneuronal cells, including macrophages [4], keratinocytes [5], bronchial epithelial cells [5], and endothelial cells of arteries [6]. The function of these channels in nonneuronal cells in mammals remains to be elucidated, though it has been shown that the acetylcholine receptor alpha7 subunit is required for acetylcholine-mediated inhibition of tumor necrosis factor release by activated macrophages [4]. We show that cup-4, a gene required for efficient endocytosis of fluids by C. elegans coelomocytes, encodes a protein that is homologous to ligand-gated ion channels, with the highest degree of similarity to nicotinic acetylcholine receptors. Worms lacking CUP-4 have reduced phosphatidylinositol 4,5-bisphosphate levels at the plasma membrane, suggesting that CUP-4 regulates endocytosis through modulation of phospholipase C activity.

Objective B cell depletion therapy is widely used for treatment of cancers and autoimmune diseases. B cells are abundant in abdominal aortic aneurysms (AAA), however, it is unknown whether B cell depletion therapy affects AAA growth. Using experimental models of murine AAA, we aim to examine the effect of B cell depletion on AAA formation. Approach and Results Wild-type or Apolipoprotein E knockout mice were treated with mouse monoclonal anti-CD20 or control antibodies and subjected to an elastase perfusion or angiotensin II-infusion model to induce AAA, respectively. Anti-CD20 antibody treatment significantly depleted B1 and B2 cells, and strikingly suppressed AAA growth in both models. B cell depletion resulted in lower circulating IgM levels, but did not affect the levels of IgG or cytokine/chemokine levels. Although the total number of leukocyte remained unchanged in elastase perfused aortas following anti-CD20 antibody treatment, the number of B cell subtypes was significantly lower. Interestingly, plasmacytoid dendritic cells (pDCs) expressing the immunomodulatory enzyme indole 2,3-dioxygenase (IDO) were detected in the aortas of B cell depleted mice. In accordance with an increase in IDO+ pDCs, the number of regulatory T cells was higher while the expression of pro-inflammatory genes was lower in aortas of B cell depleted mice. In a coculture model, presence of B cells significantly lowered the number of IDO+ pDCs without affecting total pDC number. Conclusions The present results demonstrate that B cell depletion protects mice from experimental AAA formation and promotes emergence of an immunosuppressive environment in aorta.