The receptor for advanced glycation end products is a critical mediator of type 2 cytokine signaling in the lungs.

BACKGROUND: Asthma is estimated to effect more than 300 million persons worldwide, leading to nearly 250,000 deaths annually. The majority of patients with mild-to-severe asthma have what is deemed "type-2 high" asthma, which is driven by the prototypical type 2 cytokines IL-4, IL-5, and IL-13. Studies have indicated that the receptor for advanced glycation end products (RAGE) is a critical molecule in the pathogenesis of experimental asthma/allergic airway inflammation. More specifically, RAGE expressed on stromal cells, rather than hematopoietic cells, is critical to induction of asthma/allergic airway inflammation by driving type 2 inflammatory responses. However, the role of RAGE in directly mediating type 2 cytokine signaling has never been investigated. OBJECTIVE: The goal of this study was to test the hypothesis that RAGE mediates type 2 cytokine-induced signal transduction, airway inflammation, and mucus metaplasia in the lungs. METHODS: Wild-type (WT) and RAGE knockout (RAGE-/-) mice, were intranasally administered rIL-5/rIL-13 or rIL-4 alone, and signal transducer and activator of transcription 6 (STAT6) signaling, airway inflammation, and mucus metaplasia were assessed. A RAGE small-molecule antagonist was used to determine the effects of pharmacologically inhibiting RAGE on type 2 cytokine-induced effects. RESULTS: Administration of type 2 cytokines induced pronounced airway inflammation and mucus metaplasia in WT mice, which was nearly completely abrogated in RAGE-/- mice. In addition, treatment with a RAGE-specific antagonist diminished the effects of type 2 cytokines in WT mice and in primary human bronchial epithelial cell cultures. Genetic ablation or pharmacologic inhibition of RAGE blocks the effects of IL-13 and IL-4 by inhibiting sustained STAT6 activation and downstream target gene expression in mice and in human bronchial epithelial cells. CONCLUSIONS: This study is the first to indicate that RAGE is a critical component of type 2 cytokine signal transduction mechanisms, which is a driving force behind type 2-high asthma.

Alveolar Epithelial Cell-Derived Mediators: Potential Direct Regulators of Large Airway and Vascular Responses.

Bronchial epithelial cells and pulmonary endothelial cells are thought to be the primary modulators of conducting airways and vessels, respectively. However, histological examination of both mouse and human lung tissue reveals that alveolar epithelial cells (AECs) line the adventitia of large airways and vessels and thus are also in a position to directly regulate these structures. The primary purpose of this perspective is to highlight the fact that AECs coat the adventitial surface of every vessel and airway in the lung parenchyma. This localization is ideal for transmitting signals that can contribute to physiologic and pathologic responses in vessels and airways. A few examples of mediators produced by AECs that may contribute to vascular and airway responses are provided to illustrate some of the potential effects that AECs may modulate.

All the "RAGE" in lung disease: The receptor for advanced glycation endproducts (RAGE) is a major mediator of pulmonary inflammatory responses.

The receptor for advanced glycation endproducts (RAGE) is a pro-inflammatory pattern recognition receptor (PRR) that has been implicated in the pathogenesis of numerous inflammatory diseases. It was discovered in 1992 on endothelial cells and was named for its ability to bind advanced glycation endproducts and promote vascular inflammation in the vessels of patients with diabetes. Further studies revealed that RAGE is most highly expressed in lung tissue and spurred numerous explorations into RAGE's role in the lung. These studies have found that RAGE is an important mediator in allergic airway inflammation (AAI) and asthma, pulmonary fibrosis, lung cancer, chronic obstructive pulmonary disease (COPD), acute lung injury, pneumonia, cystic fibrosis, and bronchopulmonary dysplasia. RAGE has not yet been targeted in the lungs of paediatric or adult clinical populations, but the development of new ways to inhibit RAGE is setting the stage for the emergence of novel therapeutic agents for patients suffering from these pulmonary conditions.

Pulmonary receptor for advanced glycation end-products promotes asthma pathogenesis through IL-33 and accumulation of group 2 innate lymphoid cells.

BACKGROUND: Single nucleotide polymorphisms in the human gene for the receptor for advanced glycation end-products (RAGE) are associated with an increased incidence of asthma. RAGE is highly expressed in the lung and has been reported to play a vital role in the pathogenesis of murine models of asthma/allergic airway inflammation (AAI) by promoting expression of the type 2 cytokines IL-5 and IL-13. IL-5 and IL-13 are prominently secreted by group 2 innate lymphoid cells (ILC2s), which are stimulated by the proallergic cytokine IL-33. OBJECTIVE: We sought to test the hypothesis that pulmonary RAGE is necessary for allergen-induced ILC2 accumulation in the lung. METHODS: AAI was induced in wild-type and RAGE knockout mice by using IL-33, house dust mite extract, or Alternaria alternata extract. RAGE's lung-specific role in type 2 responses was explored with bone marrow chimeras and induction of gastrointestinal type 2 immune responses. RESULTS: RAGE was found to drive AAI by promoting IL-33 expression in response to allergen and by coordinating the inflammatory response downstream of IL-33. Absence of RAGE impedes pulmonary accumulation of ILC2s in models of AAI. Bone marrow chimera studies suggest that pulmonary parenchymal, but not hematopoietic, RAGE has a central role in promoting AAI. In contrast to the lung, the absence of RAGE does not affect IL-33-induced ILC2 influx in the spleen, type 2 cytokine production in the peritoneum, or mucus hypersecretion in the gastrointestinal tract. CONCLUSIONS: For the first time, this study demonstrates that a parenchymal factor, RAGE, mediates lung-specific accumulation of ILC2s.

Calpains mediate integrin attachment complex maintenance of adult muscle in Caenorhabditis elegans.

Two components of integrin containing attachment complexes, UNC-97/PINCH and UNC-112/MIG-2/Kindlin-2, were recently identified as negative regulators of muscle protein degradation and as having decreased mRNA levels in response to spaceflight. Integrin complexes transmit force between the inside and outside of muscle cells and signal changes in muscle size in response to force and, perhaps, disuse. We therefore investigated the effects of acute decreases in expression of the genes encoding these multi-protein complexes. We find that in fully developed adult Caenorhabditis elegans muscle, RNAi against genes encoding core, and peripheral, members of these complexes induces protein degradation, myofibrillar and mitochondrial dystrophies, and a movement defect. Genetic disruption of Z-line- or M-line-specific complex members is sufficient to induce these defects. We confirmed that defects occur in temperature-sensitive mutants for two of the genes: unc-52, which encodes the extra-cellular ligand Perlecan, and unc-112, which encodes the intracellular component Kindlin-2. These results demonstrate that integrin containing attachment complexes, as a whole, are required for proper maintenance of adult muscle. These defects, and collapse of arrayed attachment complexes into ball like structures, are blocked when DIM-1 levels are reduced. Degradation is also blocked by RNAi or drugs targeting calpains, implying that disruption of integrin containing complexes results in calpain activation. In wild-type animals, either during development or in adults, RNAi against calpain genes results in integrin muscle attachment disruptions and consequent sub-cellular defects. These results demonstrate that calpains are required for proper assembly and maintenance of integrin attachment complexes. Taken together our data provide in vivo evidence that a calpain-based molecular repair mechanism exists for dealing with attachment complex disruption in adult muscle. Since C. elegans lacks satellite cells, this mechanism is intrinsic to the muscles and raises the question if such a mechanism also exists in higher metazoans.

Electron microscopy remains the gold standard for the diagnosis of epithelial malignant mesothelioma: a case study.

This is a case of idiopathic epithelial malignant mesothelioma in a 47-year-old mechanic. The advent of a large battery of immunochemical markers has provided new tools for the diagnosis of mesothelioma in recent years; however, immunostaining can often be misleading or inconsistent, as demonstrated in this case. This report highlights the lasting utility of electron microscopy in the diagnosis of mesothelioma. Ultrastructural features of epithelial mesothelioma were discernable using electron microscopy even on somewhat poorly preserved chest wall biopsy specimens from paraffin blocks. These images, combined with immunostains and a fiber analysis from the lungs, allowed for a final diagnosis of a non-asbestos-related malignant epithelial mesothelioma in this patient.

It's a cell-eat-cell world: autophagy and phagocytosis.

The process of cellular eating, or the phagocytic swallowing of one cell by another, is an ancient manifestation of the struggle for life itself. Following the endosymbiotic origin of eukaryotic cells, increased cellular and then multicellular complexity was accompanied by the emergence of autophagic mechanisms for self-digestion. Heterophagy and autophagy function not only to protect the nutritive status of cells, but also as defensive responses against microbial pathogens externally or the ill effects of damaged proteins and organelles within. Because of the key roles played by phagocytosis and autophagy in a wide range of acute and chronic human diseases, pathologists have played similarly key roles in elucidating basic regulatory phases for both processes. Studies in diverse organ systems (including the brain, liver, kidney, lung, and muscle) have defined key roles for these lysosomal pathways in infection control, cell death, inflammation, cancer, neurodegeneration, and mitochondrial homeostasis. The literature reviewed here exemplifies the role of pathology in defining leading-edge questions for continued molecular and pathophysiological investigations into all forms of cellular digestion.

The ZJU index is a powerful surrogate marker for NAFLD in severely obese North American women.

INTRODUCTION: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the western world and is highly associated with multiple cardiometabolic complications. The Zhejiang University (ZJU) index was first developed to predict NAFLD in Chinese populations, where it was shown to have better predictive value than other currently used indices. The aims of the present study were to 1) determine the diagnostic accuracy of ZJU index in identifying NAFLD in a well-phenotyped cohort of obese middle-aged American women and 2) compare its performance with other non-invasive indices for NAFLD identification. METHODS: To achieve this goal, we performed a retrospective analysis of a prospectively-collected cohort of participants enrolled in a weight loss trial for severe obesity (RENEW, clinicaltrials.gov identifier: NCT00712127). One hundred and seven women between the age of 30 and 55 with obesity class II (BMI 35-39.9 kg/m2) or class III (BMI ≥ 40 kg/m2) were recruited for analyses. Hepatic steatosis was measured using liver/spleen attenuation ratio (L/S ratio) from unenhanced abdominal computed tomography. Beside ZJU index, hepatic steatosis index (HSI), lipid accumulation production index (LAPI), and visceral adiposity index (VAI) were also determined and to compare their performance in predicting NAFLD. RESULTS: Of 107 obese women in the study, 40 (37.4%) met imaging criteria for NAFLD using cut-off value of L/S ratio < 1.1. The ZJU index was positively correlated with HIS, LAPI, but not VAI. The area under the curve was highest for the ZJU index (AUC = 0.742, 95% CI:0.647-0.837), followed by HSI (AUC = 0.728, 95% CI:0.631-0.825), LAPI (AUC = 0.682, CI:0.583-0.781), and VAI (AUC = 0.621, 95% CI:0.518-0.725), respectively, using the Youden method. CONCLUSION: The ZJU index is a powerful surrogate marker for NAFLD in severely obese western females and its predictive value was better than that of other commonly used indices for predicting NAFLD. Our study is the first to suggest that the ZJU index could be a promising model for use in western as well as Chinese populations.

Wnt Pathway Inhibitor DKK1: A Potential Novel Biomarker for Adiposity.

Emerging evidence indicates that ectopic skeletal muscle adiposity may be a risk factor for type 2 diabetes (T2D), especially in persons of African ancestry. In vitro studies suggest that a Wnt pathway inhibitor, Dickkopf-related protein 1 (DKK1), plays a role in adiposity regulation and could be a biomarker for adiposity in humans. The objective of this study was to test whether serum DKK1 levels relate to adiposity measures in a cohort from an African ancestry population at high risk for T2D. Fasting serum DKK1 was measured in a sample of 159 men of African ancestry aged ≥40 years (mean age ± SD, 63.5 ± 8.2 years; mean body mass index, 27.8 ± 4.5 kg/m2). Anthropometrics included total-body and trunk adiposity measured by dual-energy x-ray absorptiometry and lower-leg skeletal muscle density measured by CT [which reflects the intramuscular adiposity content (mg/cm3)]. Serum DKK1 was positively correlated with BMI (r = 0.20; P = 0.01), waist circumference (r = 0.15; P = 0.046), DXA total-body adiposity (r = 0.24; P = 0.003), and DXA trunk adiposity (r = 0.21; P = 0.009), independent of age and height. In addition, serum DKK1 was inversely correlated with skeletal muscle density (r = -0.25; P = 0.002), independent of age, BMI, and calf muscle area. No significant correlation was found between serum DKK1 and fasting serum glucose or insulin levels or insulin resistance estimated by homeostasis model assessment. These findings suggest that higher levels of serum DKK1 may be associated with greater overall, central, and ectopic skeletal muscle adiposity. Further studies are needed to unravel the potential role of DKK1 in the regulation of adiposity in humans.

Neutrophil elastase promotes myofibroblast differentiation in lung fibrosis.

IPF is a progressive lung disorder characterized by fibroblast proliferation and myofibroblast differentiation. Although neutrophil accumulation within IPF lungs has been negatively correlated with outcomes, the role played by neutrophils in lung fibrosis remains poorly understood. We have demonstrated previously that NE promotes lung cancer cell proliferation and hypothesized that it may have a similar effect on fibroblasts. In the current study, we show that NE(-/-) mice are protected from asbestos-induced lung fibrosis. NE(-/-) mice displayed reduced fibroblast and myofibroblast content when compared with controls. NE directly both lung fibroblast proliferation and myofibroblast differentiation in vitro, as evidenced by proliferation assays, collagen gel contractility assays, and αSMA induction. Furthermore, αSMA induction occurs in a TGF-ß-independent fashion. Treatment of asbestos-recipient mice with ONO-5046, a synthetic NE antagonist, reduced hydroxyproline content. Thus, the current study points to a key role for neutrophils and NE in the progression of lung fibrosis. Lastly, the study lends rationale to use of NE-inhibitory approaches as a novel therapeutic strategy for patients with lung fibrosis.

Remote automated multi-generational growth and observation of an animal in low Earth orbit.

The ultimate survival of humanity is dependent upon colonization of other planetary bodies. Key challenges to such habitation are (patho)physiologic changes induced by known, and unknown, factors associated with long-duration and distance space exploration. However, we currently lack biological models for detecting and studying these changes. Here, we use a remote automated culture system to successfully grow an animal in low Earth orbit for six months. Our observations, over 12 generations, demonstrate that the multi-cellular soil worm Caenorhabditis elegans develops from egg to adulthood and produces progeny with identical timings in space as on the Earth. Additionally, these animals display normal rates of movement when fully fed, comparable declines in movement when starved, and appropriate growth arrest upon starvation and recovery upon re-feeding. These observations establish C. elegans as a biological model that can be used to detect changes in animal growth, development, reproduction and behaviour in response to environmental conditions during long-duration spaceflight. This experimental system is ready to be incorporated on future, unmanned interplanetary missions and could be used to study cost-effectively the effects of such missions on these biological processes and the efficacy of new life support systems and radiation shielding technologies.