Many long-lived species of animals require the function of adult stem cells throughout their lives. However, the transcriptomes of stem cells in invertebrates and vertebrates have not been compared, and consequently, ancestral regulatory circuits that control stem cell populations remain poorly defined. In this study, we have used data from high-throughput RNA sequencing to compare the transcriptomes of pluripotent adult stem cells from planarians with the transcriptomes of human and mouse pluripotent embryonic stem cells. From a stringently defined set of 4,432 orthologs shared between planarians, mice and humans, we identified 123 conserved genes that are ≥5-fold differentially expressed in stem cells from all three species. Guided by this gene set, we used RNAi screening in adult planarians to discover novel stem cell regulators, which we found to affect the stem cell-associated functions of tissue homeostasis, regeneration, and stem cell maintenance. Examples of genes that disrupted these processes included the orthologs of TBL3, PSD12, TTC27, and RACK1. From these analyses, we concluded that by comparing stem cell transcriptomes from diverse species, it is possible to uncover conserved factors that function in stem cell biology. These results provide insights into which genes comprised the ancestral circuitry underlying the control of stem cell self-renewal and pluripotency.

Background-Studies to define the overall contribution of lymphocytes to lesion formation in atherosclerosis-susceptible mice have demonstrated relatively subtle effects; the use of lymphocyte-deficient mice, however, compromises both the effector and regulatory arms of the immune system. Here, we tested the hypothesis that deletion of CXCL10 (IP-10), a chemokine specific for effector T cells that has been localized within atherosclerotic lesions, would significantly inhibit atherogenesis. Methods and Results-Compound deficient ApoeϪ/Ϫ /Cxcl10 Ϫ/Ϫ mice fed a Western-style diet for either 6 or 12 weeks demonstrated significant reductions in atherogenesis as compared with Apoe Ϫ/Ϫ controls, as assessed by both aortic en face and cross-sectional analyses. Immunohistochemical studies revealed a decrease in the accumulation of CD4 ϩ T cells, whereas quantitative polymerase chain reaction analysis of lesion-rich aortic arches demonstrated a marked reduction in mRNA for CXCR3, the CXCL10 chemokine receptor. Although overall T-cell accumulation was diminished significantly, we found evidence to suggest that regulatory T-cell (T reg ) numbers and activity were enhanced, as assessed by increased message for the T reg -specific marker Foxp3, as well as increases in immunostaining for the T reg -associated cytokines interleukin-10 and transforming growth factor-␤1. We also documented naturally occurring T reg cells in human atherosclerotic lesions. Conclusions-We provide novel evidence for a functional role for the effector T-cell chemoattractant CXCL10 in atherosclerotic lesion formation by modulating the local balance of the effector and regulatory arms of the immune system.

Background-Vascular disease can manifest as stenotic plaques or ectatic aneurysms, although the mechanisms culminating in these divergent disease manifestations remain poorly understood. T-helper type 1 cytokines, including interferon-␥ and CXCL10, have been strongly implicated in atherosclerotic plaque development. Methods and Results-Here, we specifically examined their role in the formation of abdominal aortic aneurysms in the angiotensin II-induced murine model. Unexpectedly, we found increased suprarenal aortic diameters, abdominal aortic aneurysm incidence, and aneurysmal death in apolipoprotein E-and interferon-␥-deficient (Apoe Ϫ/Ϫ /Ifng Ϫ/Ϫ ) mice compared with Apoe Ϫ/Ϫ controls, although atherosclerotic luminal plaque formation was attenuated. The interferon-␥-inducible T-cell chemoattractant CXCL10 was highly induced by angiotensin II infusion in Apoe Ϫ/Ϫ mice, but this induction was markedly attenuated in Apoe Ϫ/Ϫ /Ifng Ϫ/Ϫ mice. Apoe Ϫ/Ϫ /Cxcl10 Ϫ/Ϫ mice had decreased luminal plaque but also increased aortic size, worse morphological grades of aneurysms, and a higher incidence of death due to aortic rupture than Apoe Ϫ/Ϫ controls. Furthermore, abdominal aortic aneurysms in Apoe Ϫ/Ϫ /Cxcl10 Ϫ/Ϫ mice were enriched for non-T-helper type 1-related signals, including transforming growth factor-␤1. Treatment of Apoe Ϫ/Ϫ /Cxcl10 Ϫ/Ϫ mice with anti-transforming growth factor-␤ neutralizing antibody diminished angiotensin II-induced aortic dilation. Conclusions-The present study defines a novel pathway in which interferon-␥ and its effector, CXCL10, contribute to divergent pathways in abdominal aortic aneurysm versus plaque formation, inhibiting the former pathology but promoting the latter. Thus, efforts to develop antiinflammatory strategies for atherosclerosis must carefully consider potential effects on all manifestations of vascular disease. Key Words: aneurysm Ⅲ atherosclerosis Ⅲ immunology Ⅲ inflammation Ⅲ mice, knockout T he pathophysiological mechanisms that lead to stenotic plaques versus aneurysms, 2 distinct vascular lesions, remain poorly understood. Clinically, abdominal aortic aneurysms (AAAs) are more strongly correlated with a family history 1 and smoking 2 than are coronary stenoses. Diabetes mellitus, a strong risk factor for coronary plaques, actually protects against AAA formation in population-based studies. 3,4 Clinical Perspective p 435Chronic inflammation of the vascular wall is believed to contribute to both manifestations of arterial pathology. 5,6 Atherosclerotic plaques are marked primarily by intimal infiltration of macrophages and T cells, at least at earlier disease stages. In contrast, aneurysmal segments are characterized by macrophage, T-cell, and B-cell accumulation primarily in the media and adventitia at all stages of disease evolution. 6 Human atherosclerotic stenoses specifically express mediators characteristic of a T-helper type 1 (Th1) immune response, including interferon (IFN)-␥, as well as the IFN-␥-inducible T-cell chemoattractant IP-10 (IFN-␥-inducible Protein...

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Three-dimensional printing technology in craniomaxillofacial surgery can be classified into contour models (type I), guides (type II), splints (type III), and implants (type IV). These four methods vary in their use between craniofacial and maxillofacial surgery, reflecting their different goals. This understanding may help advance and predict three-dimensional printing applications for other types of plastic surgery and beyond.

Leukotriene B4 is a proinflammatory lipid mediator generated by the enzymes 5-lipoxygenase and leukotriene A4 hydrolase. Leukotriene B4 signals primarily through its high-affinity G protein-coupled receptor, BLT1, which is highly expressed on specific leukocyte subsets. Recent genetic studies in humans as well as knockout studies in mice have implicated the leukotriene synthesis pathway in several vascular pathologies. In this study, we tested the hypothesis that BLT1 is necessary for abdominal aortic aneurysm (AAA) formation, a major complication of atherosclerotic vascular disease. Chow-fed Apoe−/− and Apoe−/−/Blt1−/− mice were treated with a 4-wk infusion of angiotensin II (1000 ng/min/kg) beginning at 20 wk of age, in a well-established murine AAA model. We found a reduced incidence of AAA formation as well as concordant reductions in the maximum suprarenal/infrarenal diameter and total suprarenal/infrarenal area in the angiotensin II-treated Apoe−/−/Blt1−/− mice as compared with the Apoe−/− controls. Diminished AAA formation in BLT1-deficient mice was associated with significant reductions in mononuclear cell chemoattractants and leukocyte accumulation in the vessel wall, as well as striking reductions in the production of matrix metalloproteinases-2 and -9. Thus, we have shown that BLT1 contributes to the frequency and size of abdominal aortic aneurysms in mice and that BLT1 deletion in turn inhibits proinflammatory circuits and enzymes that modulate vessel wall integrity. These findings extend the role of BLT1 to a critical complication of vascular disease and underscore its potential as a target for intervention in modulating multiple pathologies related to atherosclerosis.

During adult homeostasis and regeneration, the freshwater planarian must accomplish a constant balance between cell proliferation and cell death, while also maintaining proper tissue and organ size and patterning. How these ordered processes are precisely modulated remains relatively unknown. Here we show that planarians use the downstream effector of the Hippo signaling cascade, yorkie (yki; YAP in vertebrates) to control a diverse set of pleiotropic processes in organ homeostasis, stem cell regulation, regeneration and axial patterning. We show that yki functions to maintain the homeostasis of the planarian excretory (protonephridial) system and to limit stem cell proliferation, but does not affect the differentiation process or cell death. Finally, we show that Yki acts synergistically with WNT/β-catenin signaling to repress head determination by limiting the expression domains of posterior WNT genes and that of the WNTinhibitor notum. Together, our data show that yki is a key gene in planarians that integrates stem cell proliferation control, organ homeostasis, and the spatial patterning of tissues.

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