Intestinal regeneration after irradiation: stem cells and Sox9

Whole body irradiation is a useful challenge to study the response of intestinal epithelial stem cells (IESC) to genetic damage. High dose irradiation causes complete loss of the proliferative zone within intestinal crypts excluding a few stem/multipotent cells that can regenerate the intestinal epithelial lining. Whole body irradiation models using high dose irradiation are not ideal for studying the regenerative process due to poor animal survival. Little is known about direct effects of irradiation on IESC due to lack of biomarkers. This study developed a high dose abdominal irradiation model with increased survival allowing for analysis of regeneration to day 9 after irradiation and potentially longer. The expression pattern of the putative IESC marker, Sox9, was evaluated and compared with proliferation markers. We provide evidence that differential levels of Sox9 mark subpopulations of proliferating cells. This model will be useful to evaluate therapies that increase IESC survival, proliferation and regeneration

High-Fat Diet: Bacteria Interactions Promote Intestinal Inflammation Which Precedes and Correlates with Obesity and Insulin Resistance in Mouse

Obesity induced by high fat (HF) diet is associated with inflammation which contributes to development of insulin resistance. Most prior studies have focused on adipose tissue as the source of obesity-associated inflammation. Increasing evidence links intestinal bacteria to development of diet-induced obesity (DIO). This study tested the hypothesis that HF western diet and gut bacteria interact to promote intestinal inflammation, which contributes to the progression of obesity and insulin resistance.Conventionally raised specific-pathogen free (CONV) and germ-free (GF) mice were given HF or low fat (LF) diet for 2-16 weeks. Body weight and adiposity were measured. Intestinal inflammation was assessed by evaluation of TNF-alpha mRNA and activation of a NF-kappaB(EGFP) reporter gene. In CONV but not GF mice, HF diet induced increases in body weight and adiposity. HF diet induced ileal TNF-alpha mRNA in CONV but not GF mice and this increase preceded obesity and strongly and significantly correlated with diet induced weight gain, adiposity, plasma insulin and glucose. In CONV mice HF diet also resulted in activation of NF-kappaB(EGFP) in epithelial cells, immune cells and endothelial cells of small intestine. Further experiments demonstrated that fecal slurries from CONV mice fed HF diet are sufficient to activate NF-kappaB(EGFP) in GF NF-kappaB(EGFP) mice.Bacteria and HF diet interact to promote proinflammatory changes in the small intestine, which precede weight gain and obesity and show strong and significant associations with progression of obesity and development of insulin resistance. To our knowledge, this is the first evidence that intestinal inflammation is an early consequence of HF diet which may contribute to obesity and associated insulin resistance. Interventions which limit intestinal inflammation induced by HF diet and bacteria may protect against obesity and insulin resistance

Biochromoendoscopy: molecular imaging with capsule endoscopy for detection of adenomas of the GI tract

Current capsule endoscopy (CE) provides minimally invasive technology for gastrointestinal imaging, but has limited ability to discriminate different polyp types. Near Infrared Fluorescent (NIRF) probes activated by biomarkers upregulated in adenomas (e.g., cathepsin B) are potentially powerful tools to distinguish premalignant or malignant lesions from benign or inflammatory lesions

Circulating senescent myeloid cells drive blood brain barrier breakdown and neurodegeneration

Neurodegenerative diseases (ND) are characterized by progressive loss of neuronal function. Mechanisms of ND pathogenesis are incompletely understood, hampering the development of effective therapies. Langerhans cell histiocytosis (LCH) is an inflammatory neoplastic disorder caused by hematopoietic progenitors expressing MAPK activating mutations that differentiate into senescent myeloid cells that drive lesion formation. Some patients with LCH subsequently develop progressive and incurable neurodegeneration (LCH-ND). Here, we show that LCH-ND is caused by myeloid cells that are clonal with peripheral LCH cells. We discovered that circulating BRAF V600E $^{+}$ myeloid cells cause the breakdown of the blood-brain barrier (BBB), enhancing migration into the brain parenchyma where they differentiate into senescent, inflammatory CD11a $^{+}$ macrophages that accumulate in the brainstem and cerebellum. Blocking MAPK activity and senescence programs reduced parenchymal infiltration, neuroinflammation, neuronal damage and improved neurological outcome in preclinical LCH-ND. MAPK activation and senescence programs in circulating myeloid cells represent novel and targetable mechanisms of ND

Cationic Amino Acid Transporter 2 Enhances Innate Immunity during Helicobacter pylori Infection

Once acquired, Helicobacter pylori infection is lifelong due to an inadequate innate and adaptive immune response. Our previous studies indicate that interactions among the various pathways of arginine metabolism in the host are critical determinants of outcomes following infection. Cationic amino acid transporter 2 (CAT2) is essential for transport of l-arginine (L-Arg) into monocytic immune cells during H. pylori infection. Once within the cell, this amino acid is utilized by opposing pathways that lead to elaboration of either bactericidal nitric oxide (NO) produced from inducible NO synthase (iNOS), or hydrogen peroxide, which causes macrophage apoptosis, via arginase and the polyamine pathway. Because of its central role in controlling L-Arg availability in macrophages, we investigated the importance of CAT2 in vivo during H. pylori infection. CAT2−/− mice infected for 4 months exhibited decreased gastritis and increased levels of colonization compared to wild type mice. We observed suppression of gastric macrophage levels, macrophage expression of iNOS, dendritic cell activation, and expression of granulocyte-colony stimulating factor in CAT2−/− mice suggesting that CAT2 is involved in enhancing the innate immune response. In addition, cytokine expression in CAT2−/− mice was altered from an antimicrobial Th1 response to a Th2 response, indicating that the transporter has downstream effects on adaptive immunity as well. These findings demonstrate that CAT2 is an important regulator of the immune response during H. pylori infection

Mead-halls of the Oiscingas: a new Kentish perspective on the Anglo-Saxon great hall complex phenomenon

Widely cited as a metaphor for the emergence of kingship in early medieval England, the great hall complex represents one of the most distinctive and evocative expressions of the Anglo-Saxon settlement record, yet interpretation of these sites remains underdeveloped and heavily weighted towards Yeavering. Inspired by the results of recent excavations at Lyminge, this paper undertakes a detailed comparative interrogation of three great hall complexes in Kent and exploits this new regional perspective to advance understanding of the agency and embodied meanings of these settlements as ‘theatres of power’. Explored through the thematic prisms of place, social memory and monumental hybridity, this examination leads to a new appreciation of the involvement of great hall sites in the genealogical strategies of 7th-century royal dynasties and a fresh perspective on how this remarkable yet short-lived monumental idiom was adapted to harness the symbolic capital of Romanitas

L-arginine Supplementation Improves Responses to Injury and Inflammation in Dextran Sulfate Sodium Colitis

Inflammatory bowel disease (IBD), consisting of Crohn's disease and ulcerative colitis (UC), results in substantial morbidity and is difficult to treat. New strategies for adjunct therapies are needed. One candidate is the semi-essential amino acid, L-arginine (L-Arg), a complementary medicine purported to be an enhancer of immunity and vitality in the lay media. Using dextran sulfate sodium (DSS) as a murine colonic injury and repair model with similarities to human UC, we assessed the effect of L-Arg, as DSS induced increases in colonic expression of the y+ cationic amino acid transporter 2 (CAT2) and L-Arg uptake. L-Arg supplementation improved the clinical parameters of survival, body weight loss, and colon weight, and reduced colonic permeability and the number of myeloperoxidase-positive neutrophils in DSS colitis. Luminex-based multi-analyte profiling demonstrated that there was a marked reduction in proinflammatory cytokine and chemokine expression with L-Arg treatment. Genomic analysis by microarray demonstrated that DSS-treated mice supplemented with L-Arg clustered more closely with mice not exposed to DSS than to those receiving DSS alone, and revealed that multiple genes that were upregulated or downregulated with DSS alone exhibited normalization of expression with L-Arg supplementation. Additionally, L-Arg treatment of mice with DSS colitis resulted in increased ex vivo migration of colonic epithelial cells, suggestive of increased capacity for wound repair. Because CAT2 induction was sustained during L-Arg treatment and inducible nitric oxide (NO) synthase (iNOS) requires uptake of L-Arg for generation of NO, we tested the effect of L-Arg in iNOS−/− mice and found that its benefits in DSS colitis were eliminated. These preclinical studies indicate that L-Arg supplementation could be a potential therapy for IBD, and that one mechanism of action may be functional enhancement of iNOS activity

Molecular Imaging of Gastric Neoplasia with Near-Infrared Fluorescent Activatable Probes

Gastric cancer is the second leading cause of cancer mortality worldwide and is projected to rise to tenth in all-cause mortality in the near term. Early detection requires improved sensitivity and specificity of endoscopic imaging with novel methods. The objective of this study was to evaluate the utility of activatable molecular probes for the detection of gastric cancer both in vivo and ex vivo in a preclinical model. Smad4 +/− mice, which develop spontaneous gastric neoplasia, were compared to normal wild-type controls. Cathepsin-activatable and matrix metalloproteinase (MMP)-activatable molecular probes were injected 24 hours and 6 hours before imaging, respectively. In vivo imaging was performed using quantitative tomographic near-infrared fluorescence (NIRF) imaging. For validation, ex vivo imaging and histologic examination were performed. Molecular imaging in vivo of Smad4 +/− gastric cancer murine models revealed intense activation of both cathepsin B and MMP probes. Ex vivo imaging and histology confirmed that the detected neoplasms were adenocarcinomas and hyperplastic lesions. This study provides proof of principle that the cathepsin- and MMP-activatable molecular probes are activated in the Smad4 +/− murine model of spontaneous gastric adenocarcinoma and can be imaged by both in vivo and ex vivo NIRF methods. The cathepsin probe also detects hyperplastic lesions