Sclerostin antibody increases trabecular bone and bone mechanical properties by increasing osteoblast activity damaged by whole-body irradiation in mice
Project description:Irradiation therapy causes bone deterioration and increased risk for skeletal-related events. Irradiation interferes with trabecular architecture through increased osteoclastic activity, decreased osteoblastic activity, and increased adipocyte expansion in the bone marrow (BM), which further compounds bone-related disease. Neutralizing antibodies to sclerostin (Scl-Ab) increase bone mass and strength by increasing bone formation and reducing bone resorption. We hypothesized that treatment with Scl-Ab would attenuate the adverse effects of irradiation by increasing bone volume and decreasing BM adipose tissue (BMAT), resulting in better quality bone. In this study, 12-week-old female C57BL/6J mice were exposed to 6 Gy whole-body irradiation or were non-irradiated, then administered Scl-Ab (25 mg/kg) or vehicle weekly for 5 weeks. Femoral μCT analysis confirmed that the overall effect of IR significantly decreased trabecular bone volume/total volume (Tb.BV/TV) (2-way ANOVA, p < 0.0001) with a -43.8% loss in Tb.BV/TV in the IR control group. Scl-Ab independently increased Tb.BV/TV by 3.07-fold in non-irradiated and 3.6-fold in irradiated mice (2-way ANOVA, p < 0.0001). Irradiation did not affect cortical parameters, although Scl-Ab increased cortical thickness and area significantly in both irradiated and non-irradiated mice (2-way ANOVA, p < 0.0001). Femoral mechanical testing confirmed Scl-Ab significantly increased bending rigidity and ultimate moment independently of irradiation (2-way ANOVA, p < 0.0001). Static and dynamic histomorphometry of the femoral metaphysis revealed osteoblast vigor, not number, was significantly increased in the irradiated mice treated with Scl-Ab. Systemic alterations were assessed through serum lipidomic analysis, which showed that Scl-Ab normalized lipid profiles in the irradiated group. This data supports the theory of sclerostin as a novel contributor to the regulation of osteoblast activity after irradiation. Overall, our data support the hypothesis that Scl-Ab ameliorates the deleterious effects of whole-body irradiation on bone and adipose tissue in a mouse model. Our findings suggest that future research into localized and systemic therapies after irradiation exposure is warranted.
Project description:Dose assessment is an important issue for radiation emergency medicine to determine appropriate clinical treatment. Hematopoietic tissues are extremely vulnerable to radiation exposure. A decrease in blood cell count following radiation exposure is the first quantitative bio-indicator using hematological techniques. We further examined induction of oxidative stress biomarkers in residual lymphocytes to identify new biomarkers for dosimetry. In vivo whole-body radiation to mice exposed to 5 Gy significantly induces DNA double-strand breaks, which were visualized by γ-H2AX in mouse blood cells. Mouse blood smears and peripheral blood mononuclear cells (PBMC) isolated from irradiated mice were used for immunostaining for oxidative biomarkers, parkin or Nrf2. Parkin is the E3 ubiquitin ligase, which is normally localized in the cytoplasm, is relocated to abnormal mitochondria with low membrane potential (ΔΨm), where it promotes clearance via mitophagy. Nrf2 transcription factor controls the major cellular antioxidant responses. Both markers of oxidative stress were more sensitive and persistent over time than nuclear DNA damage. In conclusion, parkin and Nrf2 are potential biomarkers for use in radiation dosimetry. Identification of several biological markers which show different kinetics for radiation response is essential for radiation dosimetry that allows the assessment of radiation injury and efficacy of clinical treatment in emergency radiation incidents. Radiation-induced oxidative damage is useful not only for radiation dose assessment but also for evaluation of radiation risks on humans.
Project description:Accidental or therapeutic total body exposure to ionizing radiation has profound pathophysiological consequences including acute radiation syndrome. Currently only investigational drugs are available in case of radiological or nuclear accidents or terrorism. Lack of selective radioprotectants for normal tissues also limits the therapeutic doses that can be delivered to treat cancers. CD47 is a receptor for the secreted protein thrombospondin-1. Blockade of thrombospondin-1 or CD47 provides local radioprotection of soft tissues and bone marrow. We now report that suppression of CD47 using an antisense morpholino increases survival of mice exposed to lethal total body irradiation. Increased survival is associated with increased peripheral circulating blood cell counts and increased proliferative capacity of bone marrow derived cells. Moreover, CD47 blockade decreased cell death while inducing a protective autophagy response in radiosensitive gastrointestinal tissues. Thus, CD47 is a new target for radiomitigation that prevents both hematopoietic and gastrointestinal radiation syndromes.
Project description:GST-TAT-SOD was the fusion of superoxide dismutase (SOD), cell-permeable peptide TAT, and glutathione-S-transferase (GST). It was proved to be a potential selective radioprotector in vitro in our previous work. This study evaluated the in vivo radioprotective activity of GST-TAT-SOD against whole-body irradiation. We demonstrated that intraperitoneal injection of 0.5 ml GST-TAT-SOD (2 kU/ml) 2 h before the 6 Gy whole-body irradiation in mice almost completely prevented the splenic damage. It could significantly enhance the splenic antioxidant activity which kept the number of splenic white pulp and consequently resisted the shrinkage of the spleen. Moreover, the thymus index, hepatic antioxidant activity, and white blood cell (WBC) count of peripheral blood in irradiated mice pretreated with GST-TAT-SOD also remarkably increased. Although the treated and untreated irradiated mice showed no significant difference in the growth rate of animal body weight at 7 days postirradiation, the highest growth rate of body weight was observed in the GST-TAT-SOD-pretreated group. Furthermore, GST-TAT-SOD pretreatment increased resistance against 8 Gy whole-body irradiation and enhanced 30 d survival. The overall effect of GST-TAT-SOD seemed to be a bit more powerful than that of amifostine. In conclusion, GST-TAT-SOD would be a safe and potentially promising radioprotector.
Project description:Whole- or partial-body exposure to ionizing radiation damages major organ systems, leading to dysfunction on both acute and chronic timescales. Radiation medical countermeasures can mitigate acute damages and may delay chronic effects when delivered within days after exposure. However, in the event of widespread radiation exposure, there will inevitably be scarce resources with limited countermeasures to distribute among the affected population. Radiation biodosimetry is necessary to separate exposed from unexposed victims and determine those who requires the most urgent care. Blood-based, microRNA signatures have great potential for biodosimetry, but the affected population in such a situation will be genetically heterogeneous and have varying miRNA responses to radiation. Thus, there is a need to understand differences in radiation-induced miRNA expression across different genetic backgrounds to develop a robust signature. We used inbred mouse strains C3H/HeJ and BALB/c mice to determine how accurate miRNA in blood would be in developing markers for radiation vs. no radiation, low dose (1 Gy, 2 Gy) vs. high dose (4 Gy, 8 Gy), and high risk (8 Gy) vs. low risk (1 Gy, 2 Gy, 4 Gy). Mice were exposed to whole-body doses of 0 Gy, 1 Gy, 2 Gy, 4 Gy, or 8 Gy of X rays. MiRNA expression changes were identified using NanoString nCounter panels on blood RNA collected 1, 2, 3 or 7 days postirradiation. Overall, C3H/HeJ mice had more differentially expressed miRNAs across all doses and timepoints than BALB/c mice. The highest amount of differential expression occurred at days 2 and 3 postirradiation for both strains. Comparison of C3H/HeJ and BALB/c expression profiles to those previously identified in C57BL/6 mice revealed 12 miRNAs that were commonly expressed across all three strains, only one of which, miR-340-5p, displayed a consistent regulation pattern in all three miRNA data. Notably multiple Let-7 family members predicted high-dose and high-risk radiation exposure (Let-7a, Let-7f, Let-7e, Let-7g, and Let-7d). KEGG pathway analysis demonstrated involvement of these predicted miRNAs in pathways related to: Fatty acid metabolism, Lysine degradation and FoxO signaling. These findings indicate differences in the miRNA response to radiation across various genetic backgrounds, and highlights key similarities, which we exploited to discover miRNAs that predict radiation exposure. Our study demonstrates the need and the utility of including multiple animal strains in developing and validating biodosimetry diagnostic signatures. From this data, we developed highly accurate miRNA signatures capable of predicting exposed and unexposed subjects within a genetically heterogeneous population as quickly as 24 h of exposure to radiation.
Project description:The renin-angiotensin system contributes to atherosclerotic lesion formation. Angiotensin-converting enzyme 2 (ACE2) catabolizes angiotensin II (Ang II) to angiotensin 1-7 (Ang-(1-7)) to limit effects of the renin-angiotensin system. The purpose of this study was to define the role of ACE2 in atherosclerosis.Male Ace2(-/y) mice in an low-density lipoprotein receptor-deficient background were fed a high-fat diet for 3 months. ACE2 deficiency increased atherosclerotic area (Ace2(+/y), 17 ± 1; Ace2(-/y), 23 ± 2 mm(2), P < 0.002). This increase was blunted by losartan. To determine whether leukocytic ACE2 influenced atherosclerosis, irradiated low-density lipoprotein receptor-deficient male mice were repopulated with bone marrow-derived cells from Ace2(+/y) or Ace2(-/y) mice and fed a high-fat diet for 3 months. ACE2 deficiency in bone marrow-derived cells increased atherosclerotic area (Ace2(+/y), 1.6 ± 0.3; Ace2(-/y), 2.8 ± 0.3 mm(2); P < 0.05). Macrophages from Ace2(-/y) mice exhibited increased Ang II secretion and elevated expression of inflammatory cytokines. Conditioned media from mouse peritoneal macrophages of Ace2(-/y) mice increased monocyte adhesion to human umbilical vein endothelial cells. Incubation of human umbilical vein endothelial cells with Ang II promoted monocyte adhesion, which was blocked by Ang-(1-7). Coinfusion of Ang-(1-7) with Ang II reduced atherosclerosis.These results demonstrate that ACE2 deficiency in bone marrow-derived cells promotes atherosclerosis through regulation of Ang II/Ang-(1-7) peptides.
Project description:We designed a study with the objective to determine the long-term radiation effects of gamma rays, originating from a single shot of Co60 at a dose of 2 Gy on the 7-month-old male mice of the ICR line in 30 days after the irradiation. The aim of this study was to characterize the behavior of animals using the Open Field test, immuno-hematological status, and morpho-functional changes in the central nervous system of mice. Irradiated animals displayed significantly different behavior in the OF in comparison with the control group. The radiation damage was confirmed by assessing the ratio of leukocytes in the peripheral blood of mice at a later date after exposure to Co60. After irradiation, a decrease in the glioneuronal complex was observed in the irritated group as well as histological changes of brain cells. To sum up, not only was the hematological status of mice altered upon the total gamma irradiation, but also their behavior, which was most probably due to significant alterations in the CNS. Study of influence of ionizing radiation on female mice, comparison between different age groups. Open Field test on the 30 days after 2 Gy of γ-rays and histological analysis indicated changes in behavioral patterns, leucocytes, and brain tissue.
Project description:Bone marrow transplantation (BMT) substantially improves 10-day survival after total body irradiation (TBI), consistent with an effect on intestinal radiation death. Total body irradiation, in addition to injuring the intestinal epithelium, also perturbs the mucosal immune system, the largest immune system in the body. This study focused on how transplanted bone marrow cells (BMCs) help restore mucosal immune cell populations after sublethal TBI (8.0 Gy). We further evaluated whether transplanted BMCs: (a) home to sites of radiation injury using green fluorescent protein labeled bone marrow; and (b) contribute to restoring the mucosal barrier in vivo. As expected, BMT accelerated recovery of peripheral blood (PB) cells. In the intestine, BMT was associated with significant early recovery of mucosal granulocytes (P = 0.005). Bone marrow transplantation did not affect mucosal macrophages or lymphocyte populations at early time points, but enhanced the recovery of these cells from day 14 onward (P = 0.03). Bone marrow transplantation also attenuated radiation-induced increase of intestinal CXCL1 and restored IL-10 levels (P = 0.001). Most importantly, BMT inhibited the post-radiation increase in intestinal permeability after 10 Gy TBI (P = 0.02) and modulated the expression of tight junction proteins (P = 0.01-0.05). Green fluorescent protein-positive leukocytes were observed both in intestinal tissue and in PB. These findings strongly suggest that BMT, in addition to enhancing general hematopoietic and immune system recovery, helps restore the intestinal immune system and enhances intestinal mucosal barrier function. These findings may be important in the development and understanding of strategies to alleviate or treat intestinal radiation toxicity.
Project description:Radiation exposure has multiple effects on the brain, behavior and cognitive functions. It has been reported that high-dose (>20 Gy) radiation-induced behavior and cognitive aberration partly associated with severe tissue destruction. Low-dose (<3 Gy) exposure can occur in radiological disasters and cerebral endovascular treatment. However, only a few reports analyzed behavior and cognitive functions after low-dose irradiation. This study was undertaken to assess the relationship between brain neurochemistry and behavioral disruption in irradiated mice. The irradiated mice (0.5 Gy, 1 Gy and 3 Gy) were tested for alteration in their normal behavior over 10 days. A serotonin (5-HT), Dopamine, gamma-Aminobutyric acid (GABA) and cortisol analysis was carried out in blood, hippocampus, amygdala and whole brain tissue. There was a significant decline in the exploratory activity of mice exposed to 3 Gy and 1 Gy radiation in an open field test. We observed a significant short-term memory loss in 3 Gy and 1 Gy irradiated mice in Y-Maze. Mice exposed to 1 Gy and 3 Gy radiation exhibited increased anxiety in an elevated plus maze (EPM). The increased anxiety and memory loss patterns were also seen in 0.5 Gy irradiated mice, but the results were not statistically significant. In this study we observed that neurotransmitters are significantly altered after irradiation, but the neuronal cells in the hippocampus were not significantly affected. This study suggests that the low-dose radiation-induced cognitive impairment may be associated with the neurochemical in low-dose irradiation and unlike the high-dose scenario might not be directly related to the morphological changes in the brain.
Project description:Obesity is a chronic, costly, and globally prevalent condition, with excess caloric intake a suspected etiologic factor. Nonsurgical treatments are modestly efficacious, and weight loss maintenance is hampered by anti-famine homeostatic mechanisms. Ghrelin, a gastric hormone linked to meal initiation, energy expenditure, and fuel partitioning, is hypothesized to facilitate weight gain and impede weight loss. Unique among known animal peptides, the serine-3 residue of ghrelin is posttranslationally acylated with an n-octanoic acid, a modification important for the peptide's active blood-brain transport and growth hormone secretagogue receptor-1 agonist activity. Pharmacological degradation of ghrelin would be hypothesized to reduce ghrelin's biological effects. To study endogenous ghrelin's role in appetite and energy expenditure, we generated antibodies that hydrolyze the octanoyl moiety of ghrelin to form des-acyl ghrelin. The most proficient antibody catalyst, GHR-11E11, was found to display a second-order rate constant of 18 M(-1) x s(-1) for the hydrolysis of ghrelin to des-acyl ghrelin. I.v. administration of GHR-11E11 (50 mg/kg) maintained a greater metabolic rate in fasting C57BL/6J mice as compared with mice receiving a control antibody and suppressed 6-h refeeding after 24 h of food deprivation. Indirect respiratory measures of metabolism after refeeding and relative fuel substrate utilization were unaffected. The results support the hypothesis that acylated ghrelin stimulates appetite and curbs energy expenditure during deficient energy intake, whereas des-acyl ghrelin does not potently share these functions. Catalytic anti-ghrelin antibodies might thereby adjunctively aid consolidation of caloric restriction-induced weight loss and might also be therapeutically relevant to Prader-Willi syndrome, characterized after infancy by hyperghrelinemia, hyperphagia, and obesity.