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The tumor microenvironment is highly heterogeneous. For gliomas, the tumor-associated inflammatory response is pivotal to support growth and invasion. Factors of glioma growth, inflammation, and invasion, such as the translocator protein (TSPO) and matrix metalloproteinases (MMP), may serve as specific imaging biomarkers of the glioma microenvironment. In this study, noninvasive imaging by PET with [18F]DPA-714 (TSPO) and [18F]BR-351 (MMP) was used for the assessment of localization and quantification of the expression of TSPO and MMP. Imaging was performed in addition to established clinical imaging biomarker of active tumor volume ([18F]FET) in conjunction with MRI. We hypothesized that each imaging biomarker revealed distinct areas of the heterogeneous glioma tissue in a mouse model of human glioma. Tracers were found to be increased 1.4- to 1.7-fold, with [18F]FET showing the biggest volume as depicted by a thresholding-based, volumes of interest analysis. Tumor areas, which could not be detected by a single tracer and/or MRI parameter alone, were measured. Specific compartments of [18F]DPA-714 (14%) and [18F]BR-351 (11%) volumes along the tumor rim could be identified. [18F]DPA-714 (TSPO) and [18F]BR-351 (MMP) matched with histology. Glioma-associated microglia/macrophages (GAM) were identified as TSPO and MMP sources. Multitracer and multimodal molecular imaging approaches may allow us to gain important insights into glioma-associated inflammation (GAM, MMP). Moreover, this noninvasive technique enables characterization of the glioma microenvironment with respect to the disease-driving cellular compartments at the various disease stages. Cancer Res; 77(8); 1831–41. ©2017 AACR.

Gli36dEGFR cells were implanted. Thereafter, two imaging sequences were conducted: In sequence 1, T2w MRI and PET with [18F]DPA-714 was performed, while [18F]BR-351 PET and [18F]FET PET were conducted at day 13 and 14, respectively. In imaging sequence 2, T2w MRI and [18F]FET PET were conducted at day 12, followed by [18F]BR-351 and [18F]DPA-714 at day 13 and 14, respectively. After the last imaging experiment, mice were sacrificed and the brains immediately harvested for further analysis.

PET and CT images were co-registered using three CT-detectable, molecular sieve spheres (# 1-3) rinsed in radiotracer solution. After segmentation of spheres in the CT image (arrows), PET and CT images were superimposed by using the automated "Landmark tool" provided by the Vinci software. The "Magic tool" was applied for minor corrections of co-registrations. The resulting resliced PET image was saved for further processing. In a second step, MR and CT images were superimposed using the "Fusion- and Magic tool". For illustration MR is pseudocolored in red, while the CT was inverted in color (black). The CT contour was further superimposed to demonstrate co-registration accuracy. Selected bone structures were used as additional quality measures of image registration. The resliced CT image was saved with the new transformation matrix. In a last step, the before mentioned transformation of the CT (CTMR) was transferred to the PET, resulting in co-registration of PET/MR/CT. This workflow was repeated for every PET scan per mouse.

(A) T/B ratios, (B-D) tracer volumes, (E-J) areas of unique tracer uptake and overlapping regions. No significant effect on volumetric data was observed based on the order of imaging experiments.

Supplementary Figure Legends 1-5

(A) An elliptical VOI (yellow) was drawn in the striatum. (B) Another elliptical VOI (green) was placed over the affected hemisphere. (C) After application of a thresholding based on the control VOI. The same original VOIs (left and middle) were used for all animals for individual thresholding.

An exemplary subset of n=6 mice were randomly assessed for intra-rater reproducibility. (A-E) [18F]DPA-714 and [18F]FET images were on two consecutive days repeatedly co-registered. Volumetry was performed twice (coreg 2 and coreg 3) and compared to the data reported in the main text (coreg 1). Dotted lines represent the overall mean for all n=20 animals reported in the main text. No significant changes for all parameters, except for the "percentage of [18F]DPA-714 only" between coreg 1 and 3, was found over the three different time points of co-registration.

International audience; Le vieillissement est associé à une accumulation de cellules sénescentes produisant un environnement cellulaire inflammatoire qui pourrait expliquer différentes maladies liées à l’âge. Diverses situations menant à la sénescence sont liées à la présence de dommages de l’ADN. De plus, de nombreux syndromes progéroïdes sont associés à une instabilité du génome ou de la structure nucléaire. Nous discuterons du lien étroit existant entre l’altération des lamines, composants de l’enveloppe nucléaire, et le vieillissement cellulaire. Nous verrons que l’altération de l’enveloppe nucléaire, comme celle observée dans la Progéria, est aussi associée à des défauts de réparation de l’ADN, à une persistance de dommages de l’ADN et à un phénotype inflammatoire.

The accumulation of senescent cells accompanies organismal aging. Senescent cells produce an inflammatory microenvironment that is conducive to the development of many age-related diseases. Here we describe the different situations leading to cellular senescence and show that these situations are frequently associated with DNA damage. We also discuss the intimate link between cell aging and perturbations in the nuclear envelope, namely in nuclear lamins, as seen in progeroid syndromes. Finally, we present evidence that these alterations are associated with DNA repair defects, the persistence of DNA damage, and an inflammatory phenotype.Le vieillissement - Une histoire de dommages de l’ADN, d’enveloppe nucléaire altérée et d’inflammation ?Le vieillissement est associé à une accumulation de cellules sénescentes produisant un environnement cellulaire inflammatoire qui pourrait expliquer différentes maladies liées à l’âge. Diverses situations menant à la sénescence sont liées à la présence de dommages de l’ADN. De plus, de nombreux syndromes progéroïdes sont associés à une instabilité du génome ou de la structure nucléaire. Nous discuterons du lien étroit existant entre l’altération des lamines, composants de l’enveloppe nucléaire, et le vieillissement cellulaire. Nous verrons que l’altération de l’enveloppe nucléaire, comme celle observée dans la Progéria, est aussi associée à des défauts de réparation de l’ADN, à une persistance de dommages de l’ADN et à un phénotype inflammatoire.

Lamin B1 controls 53BP1 recruitment to DNA damage., Double-strand breaks (DSBs) are harmful lesions and a major cause of genome instability. Studies have suggested a link between the nuclear envelope and the DNA damage response. Here, we show that lamin B1, a major component of the nuclear envelope, interacts directly with 53BP1 protein, which plays a pivotal role in the DSB repair. This interaction is dissociated after DNA damage. Lamin B1 overexpression impedes 53BP1 recruitment to DNA damage sites and leads to a persistence of DNA damage, a defect in nonhomologous end joining and an increased sensitivity to DSBs. The identification of interactions domains between lamin B1 and 53BP1 allows us to demonstrate that the defect of 53BP1 recruitment and the DSB persistence upon lamin B1 overexpression are due to sequestration of 53BP1 by lamin B1. This study highlights lamin B1 as a factor controlling the recruitment of 53BP1 to DNA damage sites upon injury.

The tumor microenvironment is highly heterogeneous. For gliomas, the tumor-associated inflammatory response is pivotal to support growth and invasion. Factors of glioma growth, inflammation, and invasion, such as the translocator protein (TSPO) and matrix metalloproteinases (MMP), may serve as specific imaging biomarkers of the glioma microenvironment. In this study, noninvasive imaging by PET with [18F]DPA-714 (TSPO) and [18F]BR-351 (MMP) was used for the assessment of localization and quantification of the expression of TSPO and MMP. Imaging was performed in addition to established clinical imaging biomarker of active tumor volume ([18F]FET) in conjunction with MRI. We hypothesized that each imaging biomarker revealed distinct areas of the heterogeneous glioma tissue in a mouse model of human glioma. Tracers were found to be increased 1.4- to 1.7-fold, with [18F]FET showing the biggest volume as depicted by a thresholding-based, volumes of interest analysis. Tumor areas, which could not be detected by a single tracer and/or MRI parameter alone, were measured. Specific compartments of [18F]DPA-714 (14%) and [18F]BR-351 (11%) volumes along the tumor rim could be identified. [18F]DPA-714 (TSPO) and [18F]BR-351 (MMP) matched with histology. Glioma-associated microglia/macrophages (GAM) were identified as TSPO and MMP sources. Multitracer and multimodal molecular imaging approaches may allow us to gain important insights into glioma-associated inflammation (GAM, MMP). Moreover, this noninvasive technique enables characterization of the glioma microenvironment with respect to the disease-driving cellular compartments at the various disease stages. Cancer Res; 77(8); 1831–41. ©2017 AACR.

KEY POINTS Vascular brain lesions and atherosclerosis are two similar conditions that are characterized by increased inflammation and oxidative stress. Non-invasive imaging in a murine model of atherosclerosis showed vascular brain damage and peripheral inflammation. In this study, exercise training reduced magnetic resonance imaging-detected abnormalities, insulin resistance and markers of oxidative stress and inflammation in old ApoE-/- mice. Our results demonstrate the protective effect of exercise on neurovascular damage in the ageing brain of ApoE-/- mice. ABSTRACT Vascular brain lesions, present in advanced atherosclerosis, share pathological hallmarks with peripheral vascular lesions, such as increased inflammation and oxidative stress. Physical activity reduces these peripheral risk factors, but its cerebrovascular effect is less documented, especially by non-invasive imaging. Through a combination of in vivo and post-mortem techniques, we aimed to characterize vascular brain damage in old ApoE-/- mice fed a high-cholesterol (HC) diet with dietary controlled intake. We then sought to determine the beneficial effects of exercise training on oxidative stress and inflammation in the brain as a treatment option in an ageing atherosclerosis mouse model. Using in vivo magnetic resonance imaging (MRI) and biological markers of oxidative stress and inflammation, we evaluated the occurrence of vascular abnormalities in the brain of HC-diet fed ApoE-/- mice >70 weeks old, its association with local and systemic oxidative stress and inflammation, and whether both can be modulated by exercise. Exercise training significantly reduced both MRI-detected abnormalities (present in 71% of untrained vs. 14% of trained mice) and oxidative stress (lipid peroxidation, 9.1 ± 1.4 vs. 5.2 ± 0.9 μmol mg-1 ; P

Purpose: Characterizing tumor heterogeneity using texture indices (TI) calculated from Positron Emission Tomography (PET) images has shown promise in predicting treatment response or patient survival in some types of cancer. Yet, the relationship between PET-derived TI, precise tracer distribution and biological heterogeneity needs to be clarified. We investigated the relationship between PET-derived TI and observations made on autoradiography and histological slides. Methods: Three mice bearing orthopically implanted mammary tumors derived from transgenic MMTV-PyMT mouse were scanned with the Inveon PET/Computerized Tomograph after injection of 18F-FDG. Tumors were then sliced, autoradiography was performed and tumor slices were stained using haematoxylin and eosin. Six TI computed from PET, autoradiography and histological images were compared to assess the ability of texture analysis to capture heterogeneity at different scales. Results: TI were significantly correlated (Spearman coefficient R between 0.57 and 0.85) between PET and autoradiography images but the TI values differed in magnitude. The TI correlation was low between histological and PET or autoradiography images (R between 0.06 and 0.54). All TI were little or moderately influenced by the difference of voxel size and spatial resolution in autoradiography images. TI measured in autoradiography images were significantly different (p

Introduction A growing area of research suggests that neuroimmunity may impact the pharmacology of opioids. Microglia is a key component of the brain immunity. Preclinical and clinical studies have demonstrated that microglial modulators may improve morphine-induced analgesia and prevent the development of tolerance and dependence. Positron emission tomography (PET) using translocator protein 18 kDa (TSPO) radioligand is a clinically validated strategy for the non-invasive detection of microglial activation. We hypothesized that TSPO PET imaging may be used to study the neuroimmune component of opioid tolerance and withdrawal. Methods Healthy rats (n = 6 in each group) received either saline or escalating doses of morphine (10–40 mg/kg) on five days to achieve tolerance and a withdrawal syndrome after morphine discontinuation. MicroPET imaging with [ 18 F]DPA-714 was performed 60 h after morphine withdrawal. Kinetic modeling was performed to estimate [ 18 F]DPA-714 volume of distribution (V T ) in several brain regions using dynamic PET images and corresponding metabolite-corrected input functions. Immunohistochemistry (IHC) experiments on striatal brain slices were performed to assess the expression of glial markers (Iba1, GFAP and CD68) during 14 days after morphine discontinuation. Results The baseline binding of [ 18 F]DPA-714 to the brain (V T = 0.086 ± 0.009 mL cm −3 ) was not increased by morphine exposure and withdrawal (V T = 0.079 ± 0.010 mL cm −3 ) indicating the absence of TSPO overexpression, even at the regional level. Accordingly, expression of glial markers did not increase after morphine discontinuation. Conclusions Morphine tolerance and withdrawal did not detectably activate microglia and had no impact on [ 18 F]DPA-714 brain kinetics in vivo.

International audience; Aim: Advanced atherosclerosis increases inflammation and stroke risk in the cerebral vasculature. Exercise is known to improve cardio-metabolic profiles when associated with a caloric restriction, but it remains debated whether it is still beneficial without the dietary control. The aim of this study was to determine both the peripheral and central effects of exercise training combined with a cholesterol-rich diet given ad libitum in old ApoE-/- mice. Methods: Forty-five-weeks old obese ApoE-/- mice fed with a high cholesterol diet ad libitum were divided into Exercise-trained (EX; running wheel free access) and Sedentary (SED) groups. Insulin tolerance and brain imaging were performed before and after the twelve-weeks training. Tissue insulin resistance, oxidative stress, and inflammation markers in plasma, aorta, and brain were then assessed. Results: In EX ApoE-/- mice, no beneficial effect of exercise was observed on weight, abdominal fat, metabolic parameters, oxidative stress, or inflammation compared to SED. Despite the regular exercise training in ApoE-/- EX mice (mean of 12.5 km/week during 12 weeks), brain inflammation imaging score was significantly associated with increased blood brain barrier (BBB) leakage evaluated by imaging follow-up (r2 = 0.87; p = 0.049) with a faster evolution compared to SED ApoE-/-mice. Conclusion: We conclude that in a context of high cardio-metabolic risk, exercise does not provide any protective effect in old ApoE-/- animals under high cholesterol diet given ad libitum. Peripheral (insulin sensitivity and oxidative/inflammatory status) but also central features (BBB preservation and protection against inflammation) did not show any benefits of exercise. Indeed, there was a fast induction of irreversible brain damage that was more pronounced in exercise-trained ApoE-/- mice.

Fluorescence imaging techniques could be used in different ways to study the interaction of aptamers with biological systems from cell culture to animal models. Here, we present the methods developed in our laboratory for fluorescently labeled aptamers, study their internalization inside living cells using time-lapse microscopy, and monitor their biodistribution in mice bearing subcutaneous xenograft tumors using planar fluorescence imaging and fluorescence diffuse optical tomography (fDOT).