Background Abdominal aortic aneurysm (AAA) formation is characterized by inflammation, smooth muscle activation and matrix degradation. This study tests the hypothesis that CD4+ T cell-produced IL-17 modulates inflammation and smooth muscle cell activation leading to the pathogenesis of AAA and that human mesenchymal stem cell (MSC) treatment can attenuate IL-17 production and AAA formation. Methods and Results Human aortic tissue demonstrated a significant increase in IL-17 and IL-23 expression in AAA patients compared to controls as analyzed by RT-PCR and ELISA. AAA formation was assessed in C57BL/6 (wild type; WT), IL-23−/− or IL-17−/− mice using an elastase-perfusion model. Heat-inactivated elastase was used as control. On days 3, 7 and 14 following perfusion, abdominal aorta diameter was measured by video micrometry, and aortic tissue was analyzed for cytokines, cell counts and IL-17-producing CD4+ T cells. Aortic diameter and cytokine production (MCP-1, RANTES, KC, TNF-α, MIP-1α and IFN-γ) was significantly attenuated in elastase-perfused IL-17−/− and IL-23−/− mice compared to WT mice on day 14. Cellular infiltration (especially IL-17-producing CD4+ T cells) was significantly attenuated in elastase-perfused IL-17−/− mice compared to WT mice on day 14. Primary aortic smooth muscle cells were significantly activated by elastase or IL-17 treatment. Furthermore, MSC treatment significantly attenuated AAA formation and IL-17 production in elastase-perfused WT mice. Conclusion These results demonstrate that CD4+ T cell-produced IL-17 plays a critical role in promoting inflammation during AAA formation and that immunomodulation of IL-17 by MSCs can offer protection against AAA formation.

Objective Abdominal aortic aneurysms (AAAs) are common, but their exact pathogenesis remains unknown and no specific medical therapies are available. We sought to evaluate interleukin-1β (IL-1β) and interleukin-1 receptor (IL-1R) in an experimental AAA model to identify novel therapeutic targets for AAA treatment. Methods and Results IL-1β mRNA and protein levels were significantly elevated in abdominal aortas of 8-12 week old male C57Bl/6 mice following elastase aortic perfusion (WT) compared to saline perfusion. Mice with genetic deletion of IL-1β (IL-1β KO) or IL-1R (IL-1R KO) that underwent elastase perfusion demonstrated significant protection against AAA formation, with maximal aortic dilations of 38.0±5.5% for IL-1β KO and 52.5±4.6% for IL-1R KO compared to 89.4±4.0% for WT mice (p<0.005). Correspondingly, IL-1β KO and IL-1R KO aortas had reduced macrophage and neutrophil staining with greater elastin preservation compared to WT. In WT mice pretreated with escalating doses of the IL-1R antagonist anakinra, there was a dose-dependent decrease in maximal aortic dilation (R=−0.676, p <0.0005). Increasing anakinra doses correlated with decreasing macrophage staining and elastin fragmentation. Lastly, WT mice treated with anakinra 3 or 7 days following AAA initiation with elastase demonstrated significant protection against AAA progression and had decreased aortic dilation compared to control mice. Conclusions IL-1β is critical for AAA initiation and progression, and IL-1β neutralization through genetic deletion or receptor antagonism attenuates experimental AAA formation. Disrupting IL-1β signaling offers a novel pathway for AAA treatment.

Background KLF4 mediates inflammatory responses following vascular injury/disease; however, the role of KLF4 in abdominal aortic aneurysms [AAA] remains unknown. The goals of the present study were to: 1) determine the role of KLF4 in experimental AAA; and 2) determine the effect of KLF4 on smooth muscle cells in AAA. Methods and Results KLF4 expression progressively increased at day 3, 7, and 14 following aortic elastase perfusion in C57BL/6 mice. Separately, loss of a KLF4 allele conferred AAA protection using ERTCre+ KLF4 flx/wt mice in the elastase AAA model. In a third set of experiments, smooth muscle specific loss of 1 and 2 KLF4 alleles resulted in progressively greater protection using novel transgenic mice (MYHCre+ flx/flx, flx/wt and wt/wt) in the elastase AAA model compared to control. Elastin degradation, MAC2, and cytokine production (MCP1, TNFα, IL23) were significantly attenuated while α-actin staining was increased in KLF4 knock-out mice versus controls. Results were verified in global KLF4 and smooth muscle specific knock-out mice using an Angiotensin II model of aneurysm formation. KLF4 inhibition with siRNA attenuated down-regulation of smooth muscle gene expression in vitro, while in vivo studies demonstrated that KLF4 binds to promoters of smooth muscle genes by ChIP analysis. Finally, human aortic aneurysms demonstrated significantly higher KLF4 expression that was localized to smooth muscle cells (SMCs). Conclusions KLF4 plays a critical role in aortic aneurysm formation via effects on SMCs. These results suggest that KLF4 regulates SMC “phenotypic switching” and could be a potential therapeutic target for AAA disease.

Background Thoracic aortic aneurysms (TAAs) are common, but experimental TAA models are limited and the role of interleukin-1β (IL-1β) is undetermined. Methods and Results IL-1β protein was measured in human TAAs and control aortas, and IL-1β protein was increased ≈20-fold in human TAAs. To develop an experimental model of TAAs, 8- to 10-week-old male C57Bl/6 mice (wild type [WT]) underwent thoracotomy with application of periadventitial elastase (WT TAA) or saline (WT control; n=30 per group). Elastase treatment to thoracic aortas resulted in progressive dilation until day 14 with maximal dilation of 99.6±24.7% compared with 14.4±8.2% for WT saline control (P<0.0001). WT TAAs demonstrated elastin fragmentation, smooth muscle cell loss, macrophage infiltration, and increased IL-1β expression. Next, TAAs were induced in mice deficient of IL-1β (IL-1β knockout) or IL-1 receptor (IL-1R knockout; n=10 each). Genetic deletion of IL-1β and IL-1R significantly decreased thoracic aortic dilation (IL-1β knockout=54.2±16.8% and IL-1R knockout=62.6±17.2% versus WT TAA=104.7±23.8%; P<0.001for both). IL-1β knockout and IL-1R knockout aortas demonstrated preserved elastin and smooth muscle cells with fewer inflammatory cells. Correspondingly, IL-1β and IL-1R knockout aortas had decreased inflammatory cytokine and matrix metalloproteinase 9 expression. Separately, WT mice pretreated with either IL-1R antagonist anakinra (100 mg/kg per day) or vehicle alone (control) underwent elastase treatment. Pretreatment of WT mice with anakinra attenuated TAA formation (control: 99.2±15.5% versus anakinra: 68.3±19.2%; P<0.005). Finally, to investigate treatment of small TAAs, WT mice were treated with anakinra 3 days after TAA induction. Anakinra treatment in WT mice with small TAAs reduced aortic dilation on day 14 (control treatment: 89.1±18.6% versus anakinra treatment: 59.7±25.7%; P=0.01). Conclusions Periadventitial application of elastase to murine thoracic aortas reproducibly produced aneurysms with molecular and histological features consistent with TAA disease. Genetic and pharmacological inhibition of IL-1β decreased TAA formation and progression, indicating that IL-1β may be a potential target for TAA treatment.

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Objective The protective effects of female gender on the development of abdominal aortic aneurysms (AAAs) have been attributed to anti-inflammatory effects of estrogen. All estrogen synthesis is dependent upon the enzyme aromatase, which is located both centrally in the ovaries and peripherally in adipose tissue, bone, and vascular smooth muscle cells. It is hypothesized that deletion of aromatase in both ovaries and peripheral tissues would diminish the protective effect of female gender and would be associated with increased aortic diameter in female mice. Methods Male and female 8–10 week-old mice with aromatase (wild type: WT) and without aromatase (ArKO) underwent elastase aortic perfusion with aortic harvest 14 days following. To evaluate the contribution of central and peripheral estrogen conversion, female WT mice were compared to female WT and ArKO mice that had undergone ovariectomy (ovx) at 6 weeks followed by elastase perfusion at 8–10 weeks. At aortic harvest, maximal aortic dilation was measured and samples were collected for immunohistochemistry and protein analysis. Serum was collected for serum estradiol concentrations. Groups were compared with analysis of variance (ANOVA). Human and mouse AAA cross-sections were analyzed with confocal immunohistochemistry for aromatase, smooth muscle markers, and macrophage markers. Results Female WT mice had significant reduction in aortic dilation compared to male WT mice (F WT: 51.5±15.1% vs. M WT: 78.7±14.9%, p<0.005). The protective effects of female gender were completely eliminated with deletion of aromatase (F ArKO: 82.6±13.8%, p<0.05 vs. F WT). Ovariectomy increased aortic dilation in WT mice (F WT ovx: 70.6±11.7%, p<0.05 vs. F WT). Aromatase deletion with ovariectomy further increased aortic dilation compared to WT ovx mice (F ArKO ovx: 87.3±14.7%, p<0.001 vs. F WT and p<0.05 vs. F WT ovx). Accordingly, female ArKO ovx mice had significantly higher levels of proinflammatory cytokines MCP-1 and IL-1β and were associated with increased macrophage staining and decreased elastin staining. Regarding serum hormone levels, decreasing estradiol levels correlated with increasing aortic diameter (R=−0.565, p<0.01). By confocal immunohistochemistry, both human and mouse AAA smooth muscle cells (smooth muscle α actin positive) and macrophages (CD68 positive or Mac-2 positive) expressed aromatase. Conclusions The protective effect of female gender on AAAs is due to estrogen synthesis and requires the presence of both ovarian and extragonadal/peripheral aromatase. Peripheral estrogen synthesis accounts for roughly half of the protective effect of female gender. If peripheral aromatase could be targeted, high levels of local estrogen could be produced and may avoid the side effects of systemic estrogen.

Abstract-Radio-frequency interference (RFI) in the spaceborne multichannel radiometer data of WindSat and the Advanced Microwave Scanning Radiometer-EOS is currently being detected using a spectral difference technique. Such a technique does not explicitly utilize multichannel correlations of radiometer data, which are key information in separating RFI from natural radiations. Furthermore, it is not optimal for radiometer data observed over ocean regions due to the inherent large natural variability of spectral difference over ocean. In this paper, we first analyzed multivariate WindSat and Scanning Multichannel Microwave Radiometer (SMMR) data in terms of channel correlation, information content, and principal components of WindSat and SMMR data. Then two methods based on channel correlation were developed for RFI detection over land and ocean. Over land, we extended the spectral difference technique using principal component analysis (PCA) of RFI indices, which integrates statistics of target emission/scattering characteristics (through RFI indices) and multivariate correlation of radiometer data into a single statistical framework of PCA. Over ocean, channel regression of X-band can account for nearly all of the natural variations in the WindSat data. Therefore, we use a channel regression-based model difference technique to directly predict RFI-free brightness temperature, and therefore RFI intensity. Although model difference technique is most desirable, it is more difficult to apply over land due to heterogeneity of land surfaces. Both methods improve our knowledge of RFI signatures in terms of channel correlations and explore potential RFI mitigation, and thus provide risk reductions for future satellite passive microwave missions such as the NPOESS Conical Scanning Microwave Imager/Sounder. The new RFI algorithms are effective in detecting RFI in the C-and X-band Windsat radiometer channels over land and ocean.Index Terms-Microwave remote sensing, radio-frequency interference (RFI), WindSat.

in seed production unless crop residue is removed. Canode and Law (1977) found that yield reductions ranged Field burning has traditionally been used to stimulate Kentucky from 40 to 80%, depending on row spacing. Mechanical bluegrass (Poa pratensis L.) seed production, but air quality issues are making this practice untenable. Our objectives were to determine removal of straw was less effective at promoting yield agronomic and crop developmental responses of 45 diverse Kentucky than open-field burning. This response is consistent with bluegrass entries under burned, mechanically removed, and residueother reports on the effect of residue on seed production retained management systems, assess the scope for improving yield (Hickey and Ensign, 1983). The yield response also varunder nonthermal residue management, and relate seed yield and turf ies depending on the amount of residue removed, with quality factors. Compared with burned treatments, yield was reduced more complete removal conducive to higher yield 27% when residue was mechanically removed from plots, and 63% (Hickey and Ensign, 1983). Chastain et al. (1997) rewhen residue was retained. Higher yield was promoted by a long ported that Kentucky bluegrass seed yield could be heading-to-anthesis period, a relatively short anthesis-to-harvest pemaintained without field burning with near complete riod, and an early harvest date (maturity). Although both seeds per straw removal and reduced stubble height. Lamb and panicle and fertile panicles per square meter were positively correlated with yield, lower yield with nonthermal residue management was