Mingcan Xia

Cathepsin K Deficiency Reduces Elastase Perfusion–Induced Abdominal Aortic Aneurysms in Mice

Objective— Cathepsin K (CatK) is one of the most potent mammalian elastases. We have previously shown increased expression of CatK in human abdominal aortic aneurysm (AAA) lesions. Whether this protease participates directly in AAA formation, however, remains unknown. Methods and Results— Mouse experimental AAA was induced with aortic perfusion of a porcine pancreatic elastase. Using this experimental model, we demonstrated that absence of CatK prevented AAA formation in mice 14 days postperfusion. CatK deficiency significantly reduced lesion CD4+ T-cell content, total lesion and medial cell proliferation and apoptosis, medial smooth muscle cell (SMC) loss, elastinolytic CatL and CatS expression, and elastin fragmentation, but it did not affect AAA lesion Mac-3+ macrophage accumulation or CD31+ microvessel numbers. In vitro studies revealed that CatK contributed importantly to CD4+ T-cell proliferation, SMC apoptosis, and other cysteinyl cathepsin and matrix metalloproteinase expression and activities in SMCs and endothelial cells but played negligible roles in microvessel growth and monocyte migration. AAA lesions from CatK-deficient mice showed reduced elastinolytic cathepsin activities compared with those from wild-type control mice. Conclusion— This study demonstrates that CatK plays an essential role in AAA formation by promoting T-cell proliferation, vascular SMC apoptosis, and elastin degradation and by affecting vascular cell protease expression and activities.

Vehicular exhaust particles promote allergic airway inflammation through an aryl hydrocarbon receptor–notch signaling cascade

BACKGROUND Traffic-related particulate matter (PM) has been linked to a heightened incidence of asthma and allergic diseases. However, the molecular mechanisms by which PM exposure promotes allergic diseases remain elusive. OBJECTIVE We sought to determine the expression, function, and regulation of pathways involved in promotion of allergic airway inflammation by PM. METHODS We used gene expression transcriptional profiling, in vitro culture assays, and in vivo murine models of allergic airway inflammation. RESULTS We identified components of the Notch pathway, most notably Jagged 1 (Jag1), as targets of PM induction in human monocytes and murine dendritic cells. PM, especially ultrafine particles, upregulated TH cytokine levels, IgE production, and allergic airway inflammation in mice in a Jag1- and Notch-dependent manner, especially in the context of the proasthmatic IL-4 receptor allele Il4raR576. PM-induced Jag1 expression was mediated by the aryl hydrocarbon receptor (AhR), which bound to and activated AhR response elements in the Jag1 promoter. Pharmacologic antagonism of AhR or its lineage-specific deletion in CD11c(+) cells abrogated the augmentation of airway inflammation by PM. CONCLUSION PM activates an AhR-Jag1-Notch cascade to promote allergic airway inflammation in concert with proasthmatic alleles.

CCR10 and its ligands in regulation of epithelial immunity and diseases

Epithelial tissues covering the external and internal surface of a body are constantly under physical, chemical or biological assaults. To protect the epithelial tissues and maintain their homeostasis, multiple layers of immune defense mechanisms are required. Besides the epithelial tissue-resident immune cells that provide the first line of defense, circulating immune cells are also recruited into the local tissues in response to challenges. Chemokines and chemokine receptors regulate tissue-specific migration, maintenance and functions of immune cells. Among them, chemokine receptor CCR10 and its ligands chemokines CCL27 and CCL28 are uniquely involved in the epithelial immunity. CCL27 is expressed predominantly in the skin by keratinocytes while CCL28 is expressed by epithelial cells of various mucosal tissues. CCR10 is expressed by various subsets of innate-like T cells that are programmed to localize to the skin during their developmental processes in the thymus. Circulating T cells might be imprinted by skin-associated antigen- presenting cells to express CCR10 for their recruitment to the skin during the local immune response. On the other hand, IgA antibody-producing B cells generated in mucosa-associated lymphoid tissues express CCR10 for their migration and maintenance at mucosal sites. Increasing evidence also found that CCR10/ligands are involved in regulation of other immune cells in epithelial immunity and are frequently exploited by epithelium-localizing or -originated cancer cells for their survival, proliferation and evasion from immune surveillance. Herein, we review current knowledge on roles of CCR10/ligands in regulation of epithelial immunity and diseases and speculate on related important questions worth further investigation.

Immune Activation Resulting from NKG2D/Ligand Interaction Promotes Atherosclerosis

Background— The interplay between the immune system and abnormal metabolic conditions sustains and propagates a vicious feedback cycle of chronic inflammation and metabolic dysfunction that is critical for atherosclerotic progression. It is well established that abnormal metabolic conditions, such as dyslipidemia and hyperglycemia, cause various cellular stress responses that induce tissue inflammation and immune cell activation, which in turn exacerbate the metabolic dysfunction. However, molecular events linking these processes are not well understood. Methods and Results— Tissues and organs of humans and mice with hyperglycemia and hyperlipidemia were examined for expression of ligands for NKG2D, a potent immune-activating receptor expressed by several types of immune cells, and the role of NKG2D in atherosclerosis and metabolic diseases was probed with the use of mice lacking NKG2D or by blocking NKG2D with monoclonal antibodies. NKG2D ligands were upregulated in multiple organs, particularly atherosclerotic aortas and inflamed livers. Ligand upregulation was induced in vitro by abnormal metabolites associated with metabolic dysfunctions. Using apolipoprotein E–deficient mouse models, we demonstrated that preventing NKG2D functions resulted in a dramatic reduction in plaque formation, suppressed systemic and organ inflammation mediated by multiple immune cell types, and alleviated abnormal metabolic conditions. Conclusions— The NKG2D/ligand interaction is a critical molecular link in the vicious cycle of chronic inflammation and metabolic dysfunction that promotes atherosclerosis and might be a useful target for therapeutic intervention in the disease.

CCR10 Is Important for the Development of Skin-Specific γδT Cells by Regulating Their Migration and Location

Unlike conventional αβ T cells, which preferentially reside in secondary lymphoid organs for adaptive immune responses, various subsets of unconventional T cells, such as the γδ T cells with innate properties, preferentially reside in epithelial tissues as the first line of defense. However, mechanisms underlying their tissue-specific development are not well understood. We report in this paper that among different thymic T cell subsets fetal thymic precursors of the prototypic skin intraepithelial Vγ3+ T lymphocytes (sIELs) were selected to display a unique pattern of homing molecules, including a high level of CCR10 expression that was important for their development into sIELs. In fetal CCR10-knockout mice, the Vγ3+ sIEL precursors developed normally in the thymus but were defective in migrating into the skin. Although the earlier defect in skin-seeding by sIEL precursors was partially compensated for by their normal expansion in the skin of adult CCR10-knockout mice, the Vγ3+ sIELs displayed abnormal morphology and increasingly accumulated in the dermal region of the skin. These findings provide definite evidence that CCR10 is important in sIEL development by regulating the migration of sIEL precursors and their maintenance in proper regions of the skin and support the notion that unique homing properties of different thymic T cell subsets play an important role in their peripheral location.

Cutting Edge: Intrinsic Programming of Thymic γδT Cells for Specific Peripheral Tissue Localization

Various innate-like T cell subsets preferentially reside in specific epithelial tissues as the first line of defense. However, mechanisms regulating their tissue-specific development are poorly understood. Using the prototypical skin intraepithelial γδT cells (sIELs) as a model, we show in this study that a TCR-mediated selection plays an important role in promoting acquisition of a specific skin-homing property by fetal thymic sIEL precursors for their epidermal location, and the skin-homing potential is intrinsically programmed even before the selection. In addition, once localized in the skin, the sIEL precursors develop into sIELs without the requirement of further TCR–ligand interaction. These studies reveal that development of the tissue-specific lymphocytes is a hard-wired process that targets them to specific tissues for proper functions.

IgE actions on CD4 + T cells, mast cells, and macrophages participate in the pathogenesis of experimental abdominal aortic aneurysms

Immunoglobulin E (IgE) activates mast cells (MCs). It remains unknown whether IgE also activates other inflammatory cells, and contributes to the pathogenesis of abdominal aortic aneurysms (AAAs). This study demonstrates that CD4+ T cells express IgE receptor FcεR1, at much higher levels than do CD8+ T cells. IgE induces CD4+ T‐cell production of IL6 and IFN‐γ, but reduces their production of IL10. FcεR1 deficiency (Fcer1a−/−) protects apolipoprotein E‐deficient (Apoe−/−) mice from angiotensin‐II infusion‐induced AAAs and reduces plasma IL6 levels. Adoptive transfer of CD4+ T cells (but not CD8+ T cells), MCs, and macrophages from Apoe−/− mice, but not those from Apoe−/− Fcer1a−/− mice, increases AAA size and plasma IL6 in Apoe−/− Fcer1a−/− recipient mice. Biweekly intravenous administration of an anti‐IgE monoclonal antibody ablated plasma IgE and reduced AAAs in Apoe−/− mice. Patients with AAAs had significantly higher plasma IgE levels than those without AAAs. This study establishes an important role of IgE in AAA pathogenesis by activating CD4+ T cells, MCs, and macrophages and supports consideration of neutralizing plasma IgE in the therapeutics of human AAAs.

The Ron Receptor Tyrosine Kinase Regulates Macrophage Heterogeneity and Plays a Protective Role in Diet-Induced Obesity, Atherosclerosis, and Hepatosteatosis

Obesity is a chronic inflammatory disease mediated in large part by the activation of inflammatory macrophages. This chronic inflammation underlies a whole host of diseases including atherosclerosis, hepatic steatosis, insulin resistance, type 2 diabetes, and cancer, among others. Macrophages are generally classified as either inflammatory or alternatively activated. Some tissue-resident macrophages are derived from yolk sac erythromyeloid progenitors and fetal liver progenitors that seed tissues during embryogenesis and have the ability to repopulate through local proliferation. These macrophages tend to be anti-inflammatory in nature and are generally involved in tissue remodeling, repair, and homeostasis. Alternatively, during chronic inflammation induced by obesity, bone marrow monocyte-derived macrophages are recruited to inflamed tissues, where they produce proinflammatory cytokines and exacerbate inflammation. The extent to which these two populations of macrophages are plastic in their phenotype remains controversial. We have demonstrated previously that the Ron receptor tyrosine kinase is expressed on tissue-resident macrophages, where it limits inflammatory macrophage activation and promotes a repair phenotype. In this study, we demonstrate that Ron is expressed in a subpopulation of macrophages during chronic inflammation induced by obesity that exhibit a repair phenotype as determined by the expression of arginase 1. In addition, we demonstrate that the Ron receptor plays a protective role in the progression of diet-induced obesity, hepatosteatosis, and atherosclerosis. These results suggest that altering macrophage heterogeneity in vivo could have the potential to alleviate obesity-associated diseases.

A Jagged 1–Notch 4 molecular switch mediates airway inflammation induced by ultrafine particles

Background Exposure to traffic‐related particulate matter promotes asthma and allergic diseases. However, the precise cellular and molecular mechanisms by which particulate matter exposure acts to mediate these effects remain unclear. Objective We sought to elucidate the cellular targets and signaling pathways critical for augmentation of allergic airway inflammation induced by ambient ultrafine particles (UFP). Methods We used in vitro cell‐culture assays with lung‐derived antigen‐presenting cells and allergen‐specific T cells and in vivo mouse models of allergic airway inflammation with myeloid lineage‐specific gene deletions, cellular reconstitution approaches, and antibody inhibition studies. Results We identified lung alveolar macrophages (AM) as the key cellular target of UFP in promoting airway inflammation. Aryl hydrocarbon receptor–dependent induction of Jagged 1 (Jag1) expression in AM was necessary and sufficient for augmentation of allergic airway inflammation by UFP. UFP promoted TH2 and TH17 cell differentiation of allergen‐specific T cells in a Jag1‐ and Notch 4–dependent manner. Treatment of mice with an anti–Notch 4 antibody abrogated exacerbation of allergic airway inflammation induced by UFP. Conclusion UFP exacerbate allergic airway inflammation by promoting a Jag1‐Notch 4–dependent interaction between AM and allergen‐specific T cells, leading to augmented TH cell differentiation. Graphical abstract Figure. No Caption available.

Gene-environment interaction between an IL4R variant and school endotoxin exposure contributes to asthma symptoms in inner-city children

Brandi T. Johnson-Weaver, PhD Susan McRitchie, MS Kelly A. Mercier, PhD Wimal Pathmasiri, PhD Susan J. Sumner, PhD Cliburn Chan, PhD Dori Germolec, PhD Michael Kulis, PhD A. Wesley Burks, MD Herman F. Staats, PhD From the Departments of Pathology and Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC; Systems and Translational Sciences Discovery– Science–Technology, RTI International, Research Triangle Park, NC; the NIH Eastern Regional Comprehensive Metabolomics Resource Core, Department of Nutrition, and the Department of Nutrition, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC; the Toxicology Branch, Division of National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC; the Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, NC. E-mail: susan_sumner@unc.edu. Or: Herman.Staats@duke.edu. Supported by the National Institutes of Health (NIH)/National Institutes of Environmental Health Sciences (1R03ES021036-01A1) in collaboration with the NIH Eastern Regional Comprehensive Metabolomics Resource Core (ERCMRC)/National Institute of Diabetes and Digestive and Kidney Diseases (1U24DK097193 to S.J.S.). Disclosure of potential conflict of interest: B. T. Johnson-Weaver’s institution received grant R03 from the National Institute of Environmental Health Sciences (NIEHS) for this work. S. McRitchie’s, W. Pathmasiri’s, and S. J. Sumner’s institutions received a grant from the University of North Carolina at Chapel Hill for this work. C. Chan’s institution received a grant from the NIEHS for this work. M. Kulis is employed by the University of North Carolina at Chapel Hill; his institution received grants from the National Institutes of Health (NIH) and Department of Defense (DOD) for other works, the NIH AITC Review Panel and Allertein. A. W. Burks received personal fees from the NIH; is an HAI Study Section review panel member; is a shareholder of Allertein; receives royalties from the American Society for Microbiology; receives payment from Elsevier as a coeditor of an allergy textbook; holds board membership from FARE, the World Health Organization, and Aimmune Therapeutics; receives grants from FARE, the NIH, and the Wallace Research Foundation; receives consultancy fees from Adept Field Solutions, Aimmune Therapeutics, Astellas Pharma Global Development, Biomerica, Evelo Biosciences/Epiva Biosciences, First Manhattan, Genentech, GLG Research, Insys Therapeutics, Intrommune Therapeutics, PPD Development, Regeneron Pharmceuticals, Sanofi US Services, SRA International, Stallergenes, UKKO, and Valeant Pharmaceuticals North America; and received the patents US-09/731375/8153414 Microbial delivery system, US-09/ 731375/8153414 Microbial delivery system, CA-2241918 HS-103 CIP: Peanut allergens and methods, US08/610424 Immunoassay for peanut allergen, EP-96933862.3 HS-103 CAP: Peanut allergens and methods, and US-13-742828/8815251 Microbial delivery system. H. F. Staats’ institution received a grant from the NIH for this work, and he was personally paid consultancy fees from Allertein, is employed by Duke University, received grants from the NIH for other works, holds patents issued with his name listed as an inventor but has not received any payments related to the patents, and receives stipend for his work as an editor from ASM. The rest of the authors declare that they have no relevant conflicts of interest.