Lung dendritic-cell metabolism underlies susceptibility to viral infection in diabetes

People with diabetes feature a life-risking susceptibility to respiratory viral infection, including influenza and SARS-CoV-2 (ref. 1), whose mechanism remains unknown. In acquired and genetic mouse models of diabetes, induced with an acute pulmonary viral infection, we demonstrate that hyperglycaemia leads to impaired costimulatory molecule expression, antigen transport and T cell priming in distinct lung dendritic cell (DC) subsets, driving a defective antiviral adaptive immune response, delayed viral clearance and enhanced mortality. Mechanistically, hyperglycaemia induces an altered metabolic DC circuitry characterized by increased glucose-to-acetyl-CoA shunting and downstream histone acetylation, leading to global chromatin alterations. These, in turn, drive impaired expression of key DC effectors including central antigen presentation-related genes. Either glucose-lowering treatment or pharmacological modulation of histone acetylation rescues DC function and antiviral immunity. Collectively, we highlight a hyperglycaemia-driven metabolic-immune axis orchestrating DC dysfunction during pulmonary viral infection and identify metabolic checkpoints that may be therapeutically exploited in mitigating exacerbated disease in infected diabetics.

Epithelial Nlrp10 inflammasome mediates protection against intestinal autoinflammation

Unlike other nucleotide oligomerization domain-like receptors, Nlrp10 lacks a canonical leucine-rich repeat domain, suggesting that it is incapable of signal sensing and inflammasome formation. Here we show that mouse Nlrp10 is expressed in distal colonic intestinal epithelial cells (IECs) and modulated by the intestinal microbiome. In vitro, Nlrp10 forms an Apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC)-dependent, m-3M3FBS-activated, polyinosinic:polycytidylic acid-modulated inflammasome driving interleukin-1β and interleukin-18 secretion. In vivo, Nlrp10 signaling is dispensable during steady state but becomes functional during autoinflammation in antagonizing mucosal damage. Importantly, whole-body or conditional IEC Nlrp10 depletion leads to reduced IEC caspase-1 activation, coupled with enhanced susceptibility to dextran sodium sulfate-induced colitis, mediated by altered inflammatory and healing programs. Collectively, understanding Nlrp10 inflammasome-dependent and independent activity, regulation and possible human relevance might facilitate the development of new innate immune anti-inflammatory interventions.

Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance

Non-nutritive sweeteners (NNS) are commonly integrated into human diet and presumed to be inert; however, animal studies suggest that they may impact the microbiome and downstream glycemic responses. We causally assessed NNS impacts in humans and their microbiomes in a randomized-controlled trial encompassing 120 healthy adults, administered saccharin, sucralose, aspartame, and stevia sachets for 2 weeks in doses lower than the acceptable daily intake, compared with controls receiving sachet-contained vehicle glucose or no supplement. As groups, each administered NNS distinctly altered stool and oral microbiome and plasma metabolome, whereas saccharin and sucralose significantly impaired glycemic responses. Importantly, gnotobiotic mice conventionalized with microbiomes from multiple top and bottom responders of each of the four NNS-supplemented groups featured glycemic responses largely reflecting those noted in respective human donors, which were preempted by distinct microbial signals, as exemplified by sucralose. Collectively, human NNS consumption may induce person-specific, microbiome-dependent glycemic alterations, necessitating future assessment of clinical implications.

Pediatric glioblastoma cells are sensitive to drugs that inhibit eIF2α dephosphorylation and its phosphomimetic S51D variant

We found that pediatric glioblastoma (PED-GBM) cell lines from diffuse intrinsic pontine glioma (DIPG) carrying the H3K27M mutation or from diffuse hemispheric glioma expressing the H3G34R mutation are sensitive to the combination of vorinostat (a histone deacetylase inhibitor) and PARP-1 inhibitors. The combined treatment increased the phosphorylation of eIF2α (P-eIF2α) relative to each drug alone and enhanced the decrease in cell survival. To explore the role played by increased P-eIF2α in modulating PED-GBM survival and response to treatments, we employed brain-penetrating inhibitors of P-eIF2α dephosphorylation: salubrinal and raphin-1. These drugs increased P-eIF2α, DNA damage, and cell death, similarly affecting the sensitivity of DIPG cells and derived neurospheres to PARP-1 inhibitors. Interestingly, these drugs also decreased the level of eIF2Bϵ (the catalytic subunit of eIF2B) and increased its phosphorylation, thereby enhancing the effect of increased P-eIF2α. Transient transfection with the S51D phosphomimetic eIF2α variant recapitulated the effect of salubrinal and raphin-1 on PED-GBM survival and sensitivity to PARP-1 inhibitors. Importantly, either salubrinal or raphin-1 dramatically increased the sensitivity of DIPG cells to radiation, the main treatment modality of PED-GBM. Finally, PED-GBM was more sensitive than normal human astrocytes to salubrinal, raphin-1, and the treatment combinations described herein. Our results indicate that combinations of histone deacetylase inhibitors and PARP-1 inhibitors should be evaluated for their toxicity and efficacy in PED-GBM patients and point to drugs that increase P-eIF2α or modulate its downstream effectors as a novel means of treating PED-GBM.

Gut microbiota modulates weight gain in mice after discontinued smoke exposure

Cigarette smoking constitutes a leading global cause of morbidity and preventable death¹, and most active smokers report a desire or recent attempt to quit². Smoking-cessation-induced weight gain (SCWG; 4.5 kg reported to be gained on average per 6-12 months, >10 kg year^-1 in 13% of those who stopped smoking³) constitutes a major obstacle to smoking abstinence⁴, even under stable^5,6 or restricted⁷ caloric intake. Here we use a mouse model to demonstrate that smoking and cessation induce a dysbiotic state that is driven by an intestinal influx of cigarette-smoke-related metabolites. Microbiome depletion induced by treatment with antibiotics prevents SCWG. Conversely, fecal microbiome transplantation from mice previously exposed to cigarette smoke into germ-free mice naive to smoke exposure induces excessive weight gain across diets and mouse strains. Metabolically, microbiome-induced SCWG involves a concerted host and microbiome shunting of dietary choline to dimethylglycine driving increased gut energy harvest, coupled with the depletion of a cross-regulated weight-lowering metabolite, N-acetylglycine, and possibly by the effects of other differentially abundant cigarette-smoke-related metabolites. Dimethylglycine and N-acetylglycine may also modulate weight and associated adipose-tissue immunity under non-smoking conditions. Preliminary observations in a small cross-sectional human cohort support these findings, which calls for larger human trials to establish the relevance of this mechanism in active smokers. Collectively, we uncover a microbiome-dependent orchestration of SCWG that may be exploitable to improve smoking-cessation success and to correct metabolic perturbations even in non-smoking settings.

High-Throughput Screen Identifies Host and Microbiota Regulators of Intestinal Barrier Function

BACKGROUND & AIMS

The intestinal barrier protects intestinal cells from microbes and antigens in the lumen-breaches can alter the composition of the intestinal microbiota, the enteric immune system, and metabolism. We performed a screen to identify molecules that disrupt and support the intestinal epithelial barrier and tested their effects in mice.

METHODS

We performed an imaging-based, quantitative, high-throughput screen (using CaCo-2 and T84 cells incubated with lipopolysaccharide; tumor necrosis factor; histamine; receptor antagonists; and libraries of secreted proteins, microbial metabolites, and drugs) to identify molecules that altered epithelial tight junction (TJ) and focal adhesion morphology. We then tested the effects of TJ stabilizers on these changes. Molecules we found to disrupt or stabilize TJs were administered mice with dextran sodium sulfate-induced colitis or Citrobacter rodentium-induced intestinal inflammation. Colon tissues were collected and analyzed by histology, fluorescence microscopy, and RNA sequencing.

RESULTS

The screen identified numerous compounds that disrupted or stabilized (after disruption) TJs and monolayers of epithelial cells. We associated distinct morphologic alterations with changes in barrier function, and identified a variety of cytokines, metabolites, and drugs (including inhibitors of actomyosin contractility) that prevent disruption of TJs and restore TJ integrity. One of these disruptors (putrescine) disrupted TJ integrity in ex vivo mouse colon tissues; administration to mice exacerbated colon inflammation, increased gut permeability, reduced colon transepithelial electrical resistance, increased pattern recognition receptor ligands in mesenteric lymph nodes, and decreased colon length and survival times. Putrescine also increased intestine levels and fecal shedding of viable C rodentium, increased bacterial attachment to the colonic epithelium, and increased levels of inflammatory cytokines in colon tissues. Colonic epithelial cells from mice given putrescine increased expression of genes that regulate metal binding, oxidative stress, and cytoskeletal organization and contractility. Co-administration of taurine with putrescine blocked disruption of TJs and the exacerbated inflammation.

CONCLUSIONS

We identified molecules that disrupt and stabilize intestinal epithelial TJs and barrier function and affect development of colon inflammation in mice. These agents might be developed for treatment of barrier intestinal impairment-associated and inflammatory disorders in patients, or avoided to prevent inflammation.

Time-space Fourier κω' filter for motion artifacts compensation during transcranial fluorescence brain imaging

Intravital imaging of brain vasculature through the intact cranium in vivo is based on the evolution of the fluorescence intensity and provides an ability to characterize various physiological processes in the natural context of cellular resolution. The involuntary motions of the examined subjects often limit in vivo non-invasive functional optical imaging. Conventional imaging diagnostic modalities encounter serious difficulties in correction of artificial motions, associated with fast high dynamics of the intensity values in the collected image sequences, when a common reference cannot be provided. In the current report, we introduce an alternative solution based on a time-space Fourier transform method so-called K-Omega. We demonstrate that the proposed approach is effective for image stabilization of fast dynamic image sequences and can be used autonomously without supervision and assignation of a reference image.

Induction of Nitric-Oxide Metabolism in Enterocytes Alleviates Colitis and Inflammation-Associated Colon Cancer

Nitric oxide (NO) plays an established role in numerous physiological and pathological processes, but the specific cellular sources of NO in disease pathogenesis remain unclear, preventing the implementation of NO-related therapy. Argininosuccinate lyase (ASL) is the only enzyme able to produce arginine, the substrate for NO generation by nitric oxide synthase (NOS) isoforms. Here, we generated cell-specific conditional ASL knockout mice in combination with genetic and chemical colitis models. We demonstrate that NO derived from enterocytes alleviates colitis by decreasing macrophage infiltration and tissue damage, whereas immune cell-derived NO is associated with macrophage activation, resulting in increased severity of inflammation. We find that induction of endogenous NO production by enterocytes with supplements that upregulate ASL expression and complement its substrates results in improved epithelial integrity and alleviation of colitis and of inflammation-associated colon cancer.

IL-23-producing IL-10Rα-deficient gut macrophages elicit an IL-22-driven proinflammatory epithelial cell response

Cytokines maintain intestinal health, but precise intercellular communication networks remain poorly understood. Macrophages are immune sentinels of the intestinal tissue and are critical for gut homeostasis. Here, we show that in a murine inflammatory bowel disease (IBD) model based on macrophage-restricted interleukin-10 (IL-10) receptor deficiency (Cx3cr1Cre:Il10rafl/fl mice), proinflammatory mutant gut macrophages cause severe spontaneous colitis resembling the condition observed in children carrying IL-10R mutations. We establish macrophage-derived IL-23 as the driving factor of this pathology. Specifically, we report that Cx3cr1Cre:Il10rafl/fl:Il23afl/fl mice harboring macrophages deficient for both IL-10R and IL-23 are protected from colitis. By analyzing the epithelial response to proinflammatory macrophages, we provide evidence that T cells of colitic animals produce IL-22, which induces epithelial chemokine expression and detrimental neutrophil recruitment. Collectively, we define macrophage-specific contributions to the induction and pathogenesis of colitis, as manifested in mice harboring IL-10R deficiencies and human IBDs.

Post-Antibiotic Gut Mucosal Microbiome Reconstitution Is Impaired by Probiotics and Improved by Autologous FMT

Probiotics are widely prescribed for prevention of antibiotics-associated dysbiosis and related adverse effects. However, probiotic impact on post-antibiotic reconstitution of the gut mucosal host-microbiome niche remains elusive. We invasively examined the effects of multi-strain probiotics or autologous fecal microbiome transplantation (aFMT) on post-antibiotic reconstitution of the murine and human mucosal microbiome niche. Contrary to homeostasis, antibiotic perturbation enhanced probiotics colonization in the human mucosa but only mildly improved colonization in mice. Compared to spontaneous post-antibiotic recovery, probiotics induced a markedly delayed and persistently incomplete indigenous stool/mucosal microbiome reconstitution and host transcriptome recovery toward homeostatic configuration, while aFMT induced a rapid and near-complete recovery within days of administration. In vitro, Lactobacillus-secreted soluble factors contributed to probiotics-induced microbiome inhibition. Collectively, potential post-antibiotic probiotic benefits may be offset by a compromised gut mucosal recovery, highlighting a need of developing aFMT or personalized probiotic approaches achieving mucosal protection without compromising microbiome recolonization in the antibiotics-perturbed host.

Combined laser speckle imaging and fluorescent intravital microscopy for monitoring acute vascular permeability reaction

Optical clearing agents (OCAs) and many chemicals are widely used in functional diagnosis of skin tissues. Numerous studies are associated with the transcutaneous diffusion of OCA in epidermal, dermal, and hypodermal tissues, which results in changing their optical properties. In addition, an objective approach that is suitable for screening the influence of utilized OCA, as well as various chemical agents, synthetics, and nanomaterials, on blood and lymph flows is highly desirable. In our study, a highly sensitive laser speckle imaging (LSI) system and fluorescent intravital microscopy (FIM) were used team-wise to inspect the acute skin vascular permeability reaction in mouse ear during the local application of OCA on the skin surface. Fluorescent contrast material administrated intravenously was used for quantitatively assessing the intensity of vascular permeability reaction and the strength of skin irritation. The obtained results suggest that a combined use of LSI and FIM is highly effective for monitoring the cutaneous vascular permeability reaction, with great potential for assessment of allergic reactions of skin in response to interactions with chemical substances.

The Likelihood of Misidentifying Rodent Pasteurellaceae by Using Results from a Single PCR Assay

The precise identification of rodent Pasteurellaceae is known to be highly challenging. An unknown strain of Pasteurellaceae appeared and rapidly spread throughout our animal facilities. Standard microbiology, combined with biochemical analysis, suggested that the bacteria strain was Rodentibacter pneumotropicus or R. heylii. We submitted samples of the unknown bacteria and known isolates of R. pneumotropicus, R. heylii, and Muribacter muris, to 2 service laboratories that provide animal health monitoring. Results of microbiology tests performed by both laboratories, species-specific PCR analysis performed by one laboratory, and independent 16S rRNA gene sequencing yielded identical identification of the unknown bacteria as Pasteurellaceae (Pasteurella spp.) and not R. pneumotropicus or R. heylii. In contrast, the similarly intended PCR assay performed by the other laboratory identified the bacteria as R. heylii. Careful evaluation of all of the results led us to conclude that the correct identification of the bacteria is Pasteurellaceae. From our experience, we recommend that a combination of several methods should be used to achieve correct identification of rodent Pasteurellaceae. Specifically, we advise that all primer sets used should be disclosed when reporting PCR test results, including in health reports provided by service laboratories and animal vendors. Careful, correct, and informative health monitoring reports are most beneficial to animal researchers and caretakers who might encounter the presence and effects of rodent Pasteurellaceae.

Regulatory Forum Opinion Piece*: Imaging Applications in Toxicologic Pathology-Recommendations for Use in Regulated Nonclinical Toxicity Studies

Available imaging systems for use in preclinical toxicology studies increasingly show utility as important tools in the toxicologic pathologist's armamentarium, permit longitudinal evaluation of functional and morphological changes in tissues, and provide important information such as organ and lesion volume not obtained by conventional toxicology study parameters. Representative examples of practical imaging applications in toxicology research and preclinical studies are presented for ultrasound, positron emission tomography/single-photon emission computed tomography, optical, magnetic resonance imaging, and matrix-assisted laser desorption ionization-imaging mass spectrometry imaging. Some of the challenges for making imaging systems good laboratory practice-compliant for regulatory submission are presented. Use of imaging data on a case-by-case basis as part of safety evaluation in regulatory submissions is encouraged.

Hyperglycemia drives intestinal barrier dysfunction and risk for enteric infection

Obesity, diabetes, and related manifestations are associated with an enhanced, but poorly understood, risk for mucosal infection and systemic inflammation. Here, we show in mouse models of obesity and diabetes that hyperglycemia drives intestinal barrier permeability, through GLUT2-dependent transcriptional reprogramming of intestinal epithelial cells and alteration of tight and adherence junction integrity. Consequently, hyperglycemia-mediated barrier disruption leads to systemic influx of microbial products and enhanced dissemination of enteric infection. Treatment of hyperglycemia, intestinal epithelial-specific GLUT2 deletion, or inhibition of glucose metabolism restores barrier function and bacterial containment. In humans, systemic influx of intestinal microbiome products correlates with individualized glycemic control, indicated by glycated hemoglobin levels. Together, our results mechanistically link hyperglycemia and intestinal barrier function with systemic infectious and inflammatory consequences of obesity and diabetes.

Assessing Mucosal Inflammation in a DSS-Induced Colitis Mouse Model by MR Colonography

Inflammatory bowel disease (IBD) is characterized by a chronic flaring inflammation of the gastrointestinal tract. To determine disease activity, the inflammatory state of the colon should be assessed. Endoscopy in patients with IBD aids visualization of mucosal inflammation. However, because the mucosa is fragile, there is a significant risk of perforation. In addition, the technique is based on grading of the entire colon, which is highly operator-dependent. An improved, noninvasive, objective magnetic resonance imaging (MRI) technique will effectively assess pathologies in the small intestinal mucosa, more specifically, along the colon, and the bowel wall and surrounding structures. Here, dextran sodium sulfate polymer induced acute colitis in mice that was subsequently characterized by multisection magnetic resonance colonography. This study aimed to develop a noninvasive, objective, quantitative MRI technique for detecting mucosal inflammation in a dextran sodium sulfate–induced colitis mouse model. MRI results were correlated with endoscopic and histopathological evaluations.

Persistent microbiome alterations modulate the rate of post-dieting weight regain

In tackling the obesity pandemic, considerable efforts are devoted to the development of effective weight reduction strategies, yet many dieting individuals fail to maintain a long-term weight reduction, and instead undergo excessive weight regain cycles. The mechanisms driving recurrent post-dieting obesity remain largely elusive. Here we identify an intestinal microbiome signature that persists after successful dieting of obese mice and contributes to faster weight regain and metabolic aberrations upon re-exposure to obesity-promoting conditions. Faecal transfer experiments show that the accelerated weight regain phenotype can be transmitted to germ-free mice. We develop a machine-learning algorithm that enables personalized microbiome-based prediction of the extent of post-dieting weight regain. Additionally, we find that the microbiome contributes to diminished post-dieting flavonoid levels and reduced energy expenditure, and demonstrate that flavonoid-based 'post-biotic' intervention ameliorates excessive secondary weight gain. Together, our data highlight a possible microbiome contribution to accelerated post-dieting weight regain, and suggest that microbiome-targeting approaches may help to diagnose and treat this common disorder.

Subcutaneous Compared with Intraperitoneal KetamineXylazine for Anesthesia of Mice

Mice are commonly anesthetized intraperitoneally with a ketamine-xylazine (KX) solution. Although this route of administration allows rapid uptake of the injected drugs, its disadvantages and potential risks include pain, peritoneal irritation, and perforation of an abdominal organ; some of the risks depend on the operator's experience. We compared the efficacy of intraperitoneal and subcutaneous administration of KX in HSD:ICR, BALB/cOlaHsd, and C57BL/6JOlaHsd mice in terms of time to onset and duration of surgical anesthesia, procedure safety, and mortality. Male and female mice (n = 20 each sex and strain) were anesthetized by using the same dose of intraperitoneal or subcutaneous KX. Time to onset and duration of immobilization and time to onset and duration of surgical anesthesia according to the pedal reflex differed significantly between strains. Within each strain, the durations of immobilization and surgical anesthesia were comparable between the routes of administration. The sex of the mouse but not the route of administration influenced whether surgical anesthesia was achieved. None of the subcutaneously-injected mice died. After intraperitoneal injections, 30% of the female mice died, compared with 3% of the male. In addition, fewer female mice achieved surgical anesthesia, suggesting a narrow therapeutic window for intraperitoneal KX in female mice. In conclusion, surgical anesthesia of mice with subcutaneous KX (K, 191.25 mg/kg; X, 4.25 mg/kg) seems to be safe, and the subcutaneous route is generally just as effective as the intraperitoneal route. The variability among mouse strains and between sexes requires further investigation to determine the optimal dosage.

The Spectrum and Regulatory Landscape of Intestinal Innate Lymphoid Cells Are Shaped by the Microbiome

Innate lymphoid cells (ILCs) are critical modulators of mucosal immunity, inflammation, and tissue homeostasis, but their full spectrum of cellular states and regulatory landscapes remains elusive. Here, we combine genome-wide RNA-seq, ChIP-seq, and ATAC-seq to compare the transcriptional and epigenetic identity of small intestinal ILCs, identifying thousands of distinct gene profiles and regulatory elements. Single-cell RNA-seq and flow and mass cytometry analyses reveal compartmentalization of cytokine expression and metabolic activity within the three classical ILC subtypes and highlight transcriptional states beyond the current canonical classification. In addition, using antibiotic intervention and germ-free mice, we characterize the effect of the microbiome on the ILC regulatory landscape and determine the response of ILCs to microbial colonization at the single-cell level. Together, our work characterizes the spectrum of transcriptional identities of small intestinal ILCs and describes how ILCs differentially integrate signals from the microbial microenvironment to generate phenotypic and functional plasticity.

ADAR1 deletion induces NFκB and interferon signaling dependent liver inflammation and fibrosis

Adenosine deaminase acting on RNA (ADAR) 1 binds and edits double-stranded (ds) RNA secondary structures found mainly within untranslated regions of many transcripts. In the current research, our aim was to study the role of ADAR1 in liver homeostasis. As previous studies show a conserved immunoregulatory function for ADAR1 in mammalians, we focused on its role in preventing chronic hepatic inflammation and the associated activation of hepatic stellate cells to produce extracellular matrix and promote fibrosis. We show that hepatocytes specific ADAR1 knock out (KO) mice display massive liver damage with multifocal inflammation and fibrogenesis. The bioinformatics analysis of the microarray gene-expression datasets of ADAR1 KO livers reveled a type-I interferons signature and an enrichment for immune response genes compared to control littermate livers. Furthermore, we found that in vitro silencing of ADAR1 expression in HepG2 cells leads to enhanced transcription of NFκB target genes, foremost of the pro-inflammatory cytokines IL6 and IL8. We also discovered immune cell-independent paracrine signaling among ADAR1-depleted HepG2 cells and hepatic stellate cells, leading to the activation of the latter cell type to adopt a profibrogenic phenotype. This paracrine communication dependent mainly on the production and secretion of the cytokine IL6 induced by ADAR1 silencing in hepatocytes. Thus, our findings shed a new light on the vital regulatory role of ADAR1 in hepatic immune homeostasis, chiefly its inhibitory function on the crosstalk between the NFκB and type-I interferons signaling cascades, restraining the development of liver inflammation and fibrosis.

Biopsy of the mouse prostate

Many transgenic and knockout mouse models of prostate cancer have become available over the past decade. In this paper we describe a simple biopsy technique of the murine prostate. This technique allows sequential follow-up of the prostate in an individual mouse. Its use could also reduce the number of mice used in studies of the prostate gland.

CRFR1 in AgRP Neurons Modulates Sympathetic Nervous System Activity to Adapt to Cold Stress and Fasting

Signaling by the corticotropin-releasing factor receptor type 1 (CRFR1) plays an important role in mediating the autonomic response to stressful challenges. Multiple hypothalamic nuclei regulate sympathetic outflow. Although CRFR1 is highly expressed in the arcuate nucleus (Arc) of the hypothalamus, the identity of these neurons and the role of CRFR1 here are presently unknown. Our studies show that nearly half of Arc-CRFR1 neurons coexpress agouti-related peptide (AgRP), half of which originate from POMC precursors. Arc-CRFR1 neurons are innervated by CRF neurons in the hypothalamic paraventricular nucleus, and CRF application decreases AgRP(+)CRFR1(+) neurons' excitability. Despite similar anatomy in both sexes, only female mice selectively lacking CRFR1 in AgRP neurons showed a maladaptive thermogenic response to cold and reduced hepatic glucose production during fasting. Thus, CRFR1, in a subset of AgRP neurons, plays a regulatory role that enables appropriate sympathetic nervous system activation and consequently protects the organism from hypothermia and hypoglycemia.

Genetic manipulation of iron biomineralization enhances MR relaxivity in a ferritin-M6A chimeric complex

Ferritin has gained significant attention as a potential reporter gene for in vivo imaging by magnetic resonance imaging (MRI). However, due to the ferritin ferrihydrite core, the relaxivity and sensitivity for detection of native ferritin is relatively low. We report here on a novel chimeric magneto-ferritin reporter gene - ferritin-M6A - in which the magnetite binding peptide from the magnetotactic bacteria magnetosome-associated Mms6 protein was fused to the C-terminal of murine h-ferritin. Biophysical experiments showed that purified ferritin-M6A assembled into a stable protein cage with the M6A protruding into the cage core, enabling magnetite biomineralisation. Ferritin-M6A-expressing C6-glioma cells showed enhanced (per iron) r2 relaxivity. MRI in vivo studies of ferritin-M6A-expressing tumour xenografts showed enhanced R2 relaxation rate in the central hypoxic region of the tumours. Such enhanced relaxivity would increase the sensitivity of ferritin as a reporter gene for non-invasive in vivo MRI-monitoring of cell delivery and differentiation in cellular or gene-based therapies.

Microbiota-Modulated Metabolites Shape the Intestinal Microenvironment by Regulating NLRP6 Inflammasome Signaling

Host-microbiome co-evolution drives homeostasis and disease susceptibility, yet regulatory principles governing the integrated intestinal host-commensal microenvironment remain obscure. While inflammasome signaling participates in these interactions, its activators and microbiome-modulating mechanisms are unknown. Here, we demonstrate that the microbiota-associated metabolites taurine, histamine, and spermine shape the host-microbiome interface by co-modulating NLRP6 inflammasome signaling, epithelial IL-18 secretion, and downstream anti-microbial peptide (AMP) profiles. Distortion of this balanced AMP landscape by inflammasome deficiency drives dysbiosis development. Upon fecal transfer, colitis-inducing microbiota hijacks this microenvironment-orchestrating machinery through metabolite-mediated inflammasome suppression, leading to distorted AMP balance favoring its preferential colonization. Restoration of the metabolite-inflammasome-AMP axis reinstates a normal microbiota and ameliorates colitis. Together, we identify microbial modulators of the NLRP6 inflammasome and highlight mechanisms by which microbiome-host interactions cooperatively drive microbial community stability through metabolite-mediated innate immune modulation. Therefore, targeted "postbiotic" metabolomic intervention may restore a normal microenvironment as treatment or prevention of dysbiosis-driven diseases.

A simple approach for non-invasive transcranial optical vascular imaging (nTOVI)

In vivo imaging of cerebral vasculature is highly vital for clinicians and medical researchers alike. For a number of years non-invasive optical-based imaging of brain vascular network by using standard fluorescence probes has been considered as impossible. In the current paper controverting this paradigm, we present a robust non-invasive optical-based imaging approach that allows visualize major cerebral vessels at the high temporal and spatial resolution. The developed technique is simple to use, utilizes standard fluorescent dyes, inexpensive micro-imaging and computation procedures. The ability to clearly visualize middle cerebral artery and other major vessels of brain vascular network, as well as the measurements of dynamics of blood flow are presented. The developed imaging approach has a great potential in neuroimaging and can significantly expand the capabilities of preclinical functional studies of brain and notably contribute for analysis of cerebral blood circulation in disorder models. An example of 1 × 1.5 cm color-coded image of brain blood vessels of mouse obtained in vivo by transcranial optical vascular imaging (TOVI) approach through the intact cranium.

Growth dynamics of gut microbiota in health and disease inferred from single metagenomic samples

Metagenomic sequencing increased our understanding of the role of the microbiome in health and disease, yet it only provides a snapshot of a highly dynamic ecosystem. Here, we show that the pattern of metagenomic sequencing read coverage for different microbial genomes contains a single trough and a single peak, the latter coinciding with the bacterial origin of replication. Furthermore, the ratio of sequencing coverage between the peak and trough provides a quantitative measure of a species' growth rate. We demonstrate this in vitro and in vivo, under different growth conditions, and in complex bacterial communities. For several bacterial species, peak-to-trough coverage ratios, but not relative abundances, correlated with the manifestation of inflammatory bowel disease and type II diabetes.

Transkingdom control of microbiota diurnal oscillations promotes metabolic homeostasis

All domains of life feature diverse molecular clock machineries that synchronize physiological processes to diurnal environmental fluctuations. However, no mechanisms are known to cross-regulate prokaryotic and eukaryotic circadian rhythms in multikingdom ecosystems. Here, we show that the intestinal microbiota, in both mice and humans, exhibits diurnal oscillations that are influenced by feeding rhythms, leading to time-specific compositional and functional profiles over the course of a day. Ablation of host molecular clock components or induction of jet lag leads to aberrant microbiota diurnal fluctuations and dysbiosis, driven by impaired feeding rhythmicity. Consequently, jet-lag-induced dysbiosis in both mice and humans promotes glucose intolerance and obesity that are transferrable to germ-free mice upon fecal transplantation. Together, these findings provide evidence of coordinated metaorganism diurnal rhythmicity and offer a microbiome-dependent mechanism for common metabolic disturbances in humans with aberrant circadian rhythms, such as those documented in shift workers and frequent flyers.

A simple cage-autonomous method for the maintenance of the barrier status of germ-free mice during experimentation

The use of germ-free (GF) isolators for microbiome-related research is exponentially increasing, yet limited by its cost, isolator size and potential for trans-contamination. As such, current isolator technology is highly limiting to researchers engaged in short period experiments involving multiple mouse strains and employing a variety of mono-inoculated microorganisms. In this study, we evaluate the use of positive pressure Isocages as a solution for short period studies (days to 2–3 weeks) of experimentation with GF mice at multiple simultaneous conditions. We demonstrate that this new Isocage technology is cost-effective and room-sparing, and enables maintenance of multiple simultaneous groups of GF mice. Using this technology, transferring GF mice from isolators to Isocage racks for experimentation, where they are kept under fully germ-free conditions, enables parallel inoculation with different bacterial strains and simultaneous experimentation with multiple research conditions. Altogether, the new GF Isocage technology enables the expansion of GF capabilities in a safe and cost-effective manner that can facilitate the growth, elaboration and flexibility of microbiome research.

Ear swelling test by using laser speckle imaging with a long exposure time

Laser speckle imaging with long exposure time has been applied noninvasively to visualize the immediate reaction of cutaneous vessels in mice in response to a known primary irritant and potential allergen—methyl salicylate. The compound has been used topically on the surface of the pinna and the reaction of the vascular network was examined. We demonstrate that irritant-induced acute vascular reaction can be effectively and accurately detected by laser speckle imaging technique. The current approach holds a great promise for application in routine screening of the cutaneous vascular response induced by contact agents, screenings of mouse ear swelling test, and testing the allergenic potential of new synthetic materials and healthcare pharmaceutical products.

Multimodal imaging reveals a role for Akt1 in fetal cardiac development

Even though congenital heart disease is the most prevalent malformation, little is known about how mutations affect cardiovascular function during development. Akt1 is a crucial intracellular signaling molecule, affecting cell survival, proliferation, and metabolism. The aim of this study was to determine the role of Akt1 on prenatal cardiac development. In utero echocardiography was performed in fetal wild-type, heterozygous, and Akt1-deficient mice. The same fetal hearts were imaged using ex vivo micro-computed tomography (μCT) and histology. Neonatal hearts were imaged by in vivo magnetic resonance imaging. Additional ex vivo neonatal hearts were analyzed using histology and real-time PCR of all three groups. In utero echocardiography revealed abnormal blood flow patterns at the mitral valve and reduced contractile function of Akt1 null fetuses, while ex vivo μCT and histology unraveled structural alterations such as dilated cardiomyopathy and ventricular septum defects in these fetuses. Further histological analysis showed reduced myocardial capillaries and coronary vessels in Akt1 null fetuses. At neonatal age, Akt1-deficient mice exhibited reduced survival with reduced endothelial cell density in the myocardium and attenuated cardiac expression of vascular endothelial growth factor A and collagen Iα1. To conclude, this study revealed a central role of Akt1 in fetal cardiac function and myocardial angiogenesis inducing fetal cardiomyopathy and reduced neonatal survival. This study links a specific physiological phenotype with a defined genotype, namely Akt1 deficiency, in an attempt to pinpoint intrinsic causes of fetal cardiomyopathies.

Man made disease: clinical manifestations of low phenylalanine levels in an inadequately treated phenylketonuria patient and mouse study

INTRODUCTION

Phenylalanine (Phe) deficiency and its clinical manifestations have been previously described mostly as sporadic case reports dating back to the 1960's and 1970's. In these reports, low plasma Phe levels were associated with listlessness, eczematous eruptions and failure to gain weight, most often in infants in their first year of life.

CASE REPORT

Herein we describe a 9 month old female patient with known phenylketonuria, who presented with an unusual constellation of symptoms, including severe erythema and desquamation, alopecia, keratomalacia, corneal perforation, failure to thrive and prolonged diarrhea. The diagnostic possibilities of acrodermatitis enteropathica and vitamin deficiencies were ruled out, and further investigation into her medical history led to the conclusion that during the weeks preceding the hospitalization, the patient's diet consisted of the phenylalanine-free medical formula alone, without the addition of a standard infant formula or food as recommended. Subsequently, dietary control of the blood phenylalanine levels brought swift and marked resolution of the dermatological lesions, with renewal of hair growth.

OBJECTIVE

Following this experience, and due to the relative paucity of data regarding the clinical manifestations of low serum phenylalanine levels in humans and their putative pathogenetic mechanisms, we sought to further investigate the effects of a phenylalanine-free diet in a mouse study.

MATERIALS AND METHODS

For this purpose, twenty mice were randomly allocated to receive either a phenylalanine-deficient diet (n=10) or a normal diet (n=10). Weight was measured weekly, and laboratory tests were obtained including complete blood count, electrolyte studies, and phenylalanine and tyrosine levels. Finally, necropsies and histopathological examinations of different tissues were performed in selected mice, either early after diet initiation, late after diet initiation or following re-introduction of normal diets. The study was then repeated in additional two groups of mice, for a period of up to thirteen weeks, with a total of 63 mice.

RESULTS

Gross lesions noted on necropsy in the Phe-deficient mice included scruffy coat, tendency toward weight loss, a reduction in thymic mass, and most notably severe gastric dilation, all of which were not seen in the controls. Histologic findings included thymic depletion, hepatocellular vacuolation, and exocrine pancreatic atrophy. No histopathological lesions were evident in the brain, nor were significant lesions in the eyes.

CONCLUSIONS

Diagnosis of the iatrogenic condition of phenylalanine deficiency, which manifests in gastrointestinal, dermatological and ocular findings, requires a high index of suspicion. Mice fed a phenylalanine-deficient diet display to some extent similar organ involvement, although no eye abnormalities were evident.

Label free in vivo laser speckle imaging of blood and lymph vessels

The peripheral lymphatic vascular system is a part of the immune body system comprising a complex network of lymph vessels and nodes that are flowing lymph toward the heart. Traditionally the imaging of lymphatic vessels is based on the conventional imaging modalities utilizing contrast fluorescence materials. Given the important role of the lymphatic system there is a critical need for the development of noninvasive imaging technologies for functional quantitative diagnosis of the lymph vessels and lymph flow without using foreign chemicals. We report a label free methodology for noninvasive in vivo imaging of blood and lymph vessels, using long-exposure laser speckle imaging approach. This approach entails great promise in the noninvasive studies of tissues blood and lymph vessels distribution in vivo.

Zinc supplementation augments in vivo antitumor effect of chemotherapy by restoring p53 function

Activated p53 is necessary for tumor suppression. Homeodomain-interacting protein kinase-2 (HIPK2) is a positive regulator of functional p53. HIPK2 modulates wild-type p53 activity toward proapoptotic transcription and tumor suppression by the phosphorylation of serine 46. Knock-down of HIPK2 interferes with tumor suppression and sensitivity to chemotherapy. Combined administration of adriamycin and zinc restores activity of misfolded p53 and enables the induction of its proapoptotic and tumor suppressor functions in vitro and in vivo. We therefore looked for a cancer model where HIPK2 expression is low. MMTV-neu transgenic mice overexpressing HER2/neu, develop mammary tumors at puberty with a long latency, showing very low expression of HIPK2. Here we show that whereas these tumors are resistant to adriamycin treatment, a combination of adriamycin and zinc suppresses tumor growth in vivo in these mice, an effect evidenced by the histological features of the mammary tumors. The combined treatment of adriamycin and zinc also restores wild-type p53 conformation and induces proapoptotic transcription activity. These findings may open up new possibilities for the treatment of human cancers via the combination of zinc with chemotherapeutic agents, for a selected group of patients expressing low levels of HIPK2, with an intact p53. In addition, HIPK2 may serve as a new biomarker for tumor aggressiveness.

In vivo characterization of tumor and tumor vascular network using multi-modal imaging approach

We present a multi-modal optical diagnostic approach utilizing a combined use of Fluorescence Intravital Microscopy (FIM), Dynamic Light Scattering (DLS) and Spectrally Enhanced Microscopy (SEM) modalities for in vivo imaging of tumor vascular network and blood microcirculation. FIM is used for imaging of tumor surroundings and microenvironment, SEM provides information regarding blood vessels topography, whereas DLS is applied for functional imaging of vascular network and blood microcirculation. This complementary combination of the imaging approaches is extremely useful for functional in vivo imaging of blood vasculature and tumor microenvironment. The technique has also a great potential in vascular biology and can significantly expand the capabilities of tumor angiogenesis studies and notably contribute to the development of cancer treatment.

Functional phenotyping of the maternal albumin turnover in the mouse placenta by dynamic contrast-enhanced MRI

Purpose

The purpose of this study was to develop a tool for functional phenotyping of the maternal circulation in the mouse placenta.

Procedures

In utero macromolecular dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was performed on embryonic day 10.5 (E10.5), E13.5, and E18.5. Fluorescence analysis was also used for validation of the results.

Results

The initial rate of contrast enhancement revealed an increased maternal blood volume fraction as the pregnancy progressed. Serial imaging of E10.5 and E13.5 placentas revealed a loss of contrast enhancement due to phagocytic uptake. A key application of macromolecular DCE-MRI would be to follow mouse pregnancies during fetal and placental manipulation including embryo transfer, tetraploid complementation, and fetal resorptions. We were able to resolve strain differences in ICR outbred mice carrying both ICR and C57Bl/6J embryos and to differentiate in utero resorptions from functional placentas.

Conclusions

Our results highlight the importance of the functional in utero analysis of placental vascularization in physiological phenotyping of transgenic mice and suggest MRI, particularly macromolecular DCE-MRI, as a non-invasive tool for the analysis of the placenta.

Survival and size are differentially regulated by placental and fetal PKBalpha/AKT1 in mice

The importance of placental circulation is exemplified by the correlation of placental size and blood flow with fetal weight and survival during normal and compromised human pregnancies in such conditions as preeclampsia and intrauterine growth restriction (IUGR). Using noninvasive magnetic resonance imaging, we evaluated the role of PKBalpha/AKT1, a major mediator of angiogenesis, on placental vascular function. PKBalpha/AKT1 deficiency reduced maternal blood volume fraction without affecting the integrity of the fetomaternal blood barrier. In addition to angiogenesis, PKBalpha/AKT1 regulates additional processes related to survival and growth. In accordance with reports in adult mice, we demonstrated a role for PKBalpha/AKT1 in regulating chondrocyte organization in fetal long bones. Using tetraploid complementation experiments with PKBalpha/AKT1-expressing placentas, we found that although placental PKBalpha/AKT1 restored fetal survival, fetal PKBalpha/AKT1 regulated fetal size, because tetraploid complementation did not prevent intrauterine growth retardation. Histological examination of rescued fetuses showed reduced liver blood vessel and renal glomeruli capillary density in PKBalpha/Akt1 null fetuses, both of which were restored by tetraploid complementation. However, bone development was still impaired in tetraploid-rescued PKBalpha/Akt1 null fetuses. Although PKBalpha/AKT1-expressing placentas restored chondrocyte cell number in the hypertrophic layer of humeri, fetal PKBalpha/AKT1 was found to be necessary for chondrocyte columnar organization. Remarkably, a dose-dependent phenotype was exhibited for PKBalpha/AKT1 when examining PKBalpha/Akt1 heterozygous fetuses as well as those complemented by tetraploid placentas. The differential role of PKBalpha/AKT1 on mouse fetal survival and growth may shed light on its roles in human IUGR.

Bone vascularization and trabecular bone formation are mediated by PKB alpha/Akt1 in a gene-dosage-dependent manner: in vivo and ex vivo MRI

PKBalpha/Akt1, a protein kinase, is a major mediator of angiogenic signaling. The purpose of this study was to determine the role of PKB alpha/Akt1 in bone vascularization and development. For that aim, macromolecular dynamic contrast enhanced MRI was applied to examine in vivo vascular changes in long bones of 40-day-old growing PKB alpha/Akt1-deficient, heterozygous, and wild-type mice. Ex vivo microMRI and microCT were applied to monitor the impact of PKB alpha/Akt1 gene dosage on trabecular bone formation during endochondral bone growth. PKB alpha/Akt1-deficient mice and, remarkably, also heterozygous mice showed significantly reduced blood volume fraction in the humerus compared to wild-type mice. Moreover, PKB alpha/Akt1-deficient mice showed a more severe vascular deficiency with reduced permeability. microCT and microMRI of trabeculae revealed impaired bone formation in both PKB alpha/Akt1-deficient and heterozygous mice, whereas cortical bone parameters were only reduced in PKB alpha/Akt1-deficient mice. Reduction of metaphyseal blood vessel invasion, concomitant with aberrant trabeculae and shorter long bones, demonstrates a gene-dose-dependent role for PKB alpha/Akt1 in regulation of overall size and endochondral bone growth. MRI proved to provide high sensitivity for in vivo detection of subtle gene dose effects leading to impaired bone vascularity and for uncovering changes in trabecular bone.

Ferritin as a reporter gene for MRI: chronic liver over expression of H-ferritin during dietary iron supplementation and aging

The iron storage protein, ferritin, provides an important endogenous MRI contrast that can be used to determine the level of tissue iron. In recent years the impact of modulating ferritin expression on MRI contrast and relaxation rates was evaluated by several groups, using genetically modified cells, viral gene transfer and transgenic animals. This paper reports the follow-up of transgenic mice that chronically over-expressed the heavy chain of ferritin (h-ferritin) in liver hepatocytes (liver-hfer mice) over a period of 2 years, with the aim of investigating the long-term effects of elevated level of h-ferritin on MR signal and on the well-being of the mice. Analysis revealed that aging liver-hfer mice, exposed to chronic elevated expression of h-ferritin, have increased R(2) values compared to WT. As expected for ferritin, R(2) difference was strongly enhanced at high magnetic field. Histological analysis of these mice did not reveal liver changes with prolonged over expression of ferritin, and no differences could be detected in other organs. Furthermore, dietary iron supplementation significantly affected MRI contrast, without affecting animal wellbeing, for both wildtype and ferritin over expressing transgenic mice. These results suggest the safety of ferritin over-expression, and support the use of h-ferritin as a reporter gene for MRI.

Ferritin nanoparticles as magnetic resonance reporter gene

Dynamic imaging of gene expression in live animals is among the exciting challenges of molecular imaging. To achieve that, one of the approaches is to use reporter genes that encode for the synthesis of easily detectable products. Such reporter genes can be designed to be expressed under the control of the regulatory elements included in a promoter region of a gene of interest, thus allowing the use of the same reporter gene for the detection of multiple genes. The most commonly used reporter genes include the firefly light-generating enzyme luciferase and the green fluorescent protein detectable by bioluminescence and fluorescence optical imaging, respectively. Over the last years a number of studies demonstrated the ability to use the iron-binding protein ferritin as a reporter gene that allows the detection of gene expression by magnetic resonance imaging (MRI). MRI provides high spatial resolution and soft tissue contrast for deep tissues along with a large arsenal of functional and anatomical contrast mechanisms that can be correlated with gene expression, and can potentially be translated into clinical use.

Gonadotropin-regulated lymphangiogenesis in ovarian cancer is mediated by LEDGF-induced expression of VEGF-C

The risk and severity of ovarian carcinoma, the leading cause of gynecologic malignancy death, are significantly elevated in postmenopausal women. Ovarian failure at menopause, associated with a reduction in estrogen secretion, results in an increase of the gonadotropic luteinizing hormone (LH) and follicle-stimulating hormone (FSH), suggesting a role for these hormones in facilitating the progression of ovarian carcinoma. The current study examined the influence of hormonal stimulation on lymphangiogenesis in ovarian cancer cells. In vitro stimulation of ES2 ovarian carcinoma cells with LH and FSH induced expression of vascular endothelial growth factor (VEGF)-C. In vivo, ovariectomy of mice resulted in activation of the VEGF-C promoter in ovarian carcinoma xenografts, increased VEGF-C mRNA level, and enhanced tumor lymphangiogenesis and angiogenesis. Seeking the molecular mechanism, we examined the role of lens epithelium-derived growth factor (LEDGF/p75) and the possible contribution of its putative target, a conserved stress-response element identified in silico in the VEGF-C promoter. Using chromatin immunoprecipitation, we showed that LEDGF/p75 indeed binds the VEGF-C promoter, and binding is augmented by FSH. A corresponding hormonally regulated increase in the LEDGF/p75 mRNA and protein levels was observed. Suppression of LEDGF/p75 expression using small interfering RNA, suppression of LH and FSH production using the gonadotropin-releasing hormone antagonist cetrorelix, or mutation of the conserved stress-response element suppressed the hormonally induced expression of VEGF-C. Overall, our data suggest a possible role for elevated gonadotropins in augmenting ovarian tumor lymphangiogenesis in postmenopausal women.

Interspecies comparison of prostate cancer gene-expression profiles reveals genes associated with aggressive tumors

Prostate cancer (PC) is a heterogeneous disease whose aggressive phenotype is the second leading cause of cancer-related death in men. The identification of key molecules and pathways that play a pivotal role in PC progression towards an aggressive form is crucial. A major effort towards this end has been taken by global analyses of gene expression profiles. However, the large body of data did not provide a definitive idea about the genes which are associated with the aggressive growth of PC. In order to identify such genes, we performed an interspecies comparison between several human data sets and high quality microarray data that we generated from the transgenic adenocarcinoma of mouse prostate (TRAMP) strain. The TRAMP PC mimics the histological and pathological appearance as well as the aggressive phenotype of human PC (huPC). Analysis of the microarray data, derived from microdissected TRAMP specimens removed at different stages of the disease yielded genetic signatures delineating the TRAMP PC development and progression. Comparison of the TRAMP data with a set of genes representing the core expression signature of huPC yielded a limited set genes. Some of these genes are known predictors of poor prognosis in huPC. Interestingly, the modulation of genes responsible for the invasive phenotype of huPC occurs in TRAMP already during the transition to prostate intraepithelial neoplasia (PIN) and onwards to localized tumors. We therefore suggest that critical oncogenic events leading to an aggressive phenotype of huPC can be studied in the PIN stage of TRAMP.

Cell lineage analysis of a mouse tumor

Revealing the lineage relations among cancer cells can shed light on tumor growth patterns and metastasis formation, yet cell lineages have been difficult to come by in the absence of a suitable method. We previously developed a method for reconstructing cell lineage trees from genomic variability caused by somatic mutations. Here, we apply the method to cancer and reconstruct, for the first time, a lineage tree of neoplastic and adjacent normal cells obtained by laser microdissection from tissue sections of a mouse lymphoma. Analysis of the reconstructed tree reveals that the tumor initiated from a single founder cell, approximately 5 months before diagnosis, that the tumor grew in a physically coherent manner, and that the average number of cell divisions accumulated in cancerous cells was almost twice than in adjacent normal lung epithelial cells but slightly less than the expected figure for normal B lymphocytes. The cells were also genotyped at the TP53 locus, and neoplastic cells were found to share a common mutation, which was most likely present in a heterozygous state. Our work shows that the ability to obtain data regarding the physical appearance, precise anatomic position, genotypic profile, and lineage position of single cells may be useful for investigating cancer development, progression, and interaction with the microenvironment.

Reconstruction of cell lineage trees in mice

The cell lineage tree of a multicellular organism represents its history of cell divisions from the very first cell, the zygote. A new method for high-resolution reconstruction of parts of such cell lineage trees was recently developed based on phylogenetic analysis of somatic mutations accumulated during normal development of an organism. In this study we apply this method in mice to reconstruct the lineage trees of distinct cell types. We address for the first time basic questions in developmental biology of higher organisms, namely what is the correlation between the lineage relation among cells and their (1) function, (2) physical proximity and (3) anatomical proximity. We analyzed B-cells, kidney-, mesenchymal- and hematopoietic-stem cells, as well as satellite cells, which are adult skeletal muscle stem cells isolated from their niche on the muscle fibers (myofibers) from various skeletal muscles. Our results demonstrate that all analyzed cell types are intermingled in the lineage tree, indicating that none of these cell types are single exclusive clones. We also show a significant correlation between the physical proximity of satellite cells within muscles and their lineage. Furthermore, we show that satellite cells obtained from a single myofiber are significantly clustered in the lineage tree, reflecting their common developmental origin. Lineage analysis based on somatic mutations enables performing high resolution reconstruction of lineage trees in mice and humans, which can provide fundamental insights to many aspects of their development and tissue maintenance.

Irradiation enhances the metastatic potential of prostatic small cell carcinoma xenografts

BACKGROUND

Small cell carcinoma of the prostate (SCCP) is a rare subset of prostate cancer (0.5-2% of all prostatic carcinomas), predominantly composed of neuroendocrine (NE) cells, with a very poor prognosis. Irradiation is one of the mainstay options for SCCP local treatment, yet, little is known about the clinical response of these aggressive tumors to radiotherapy.

METHODS

Using SCID mice, the response to fractionated ionizing radiation (IR) of two unique human NE xenografts of SCCP (WISH-PC2 and WM-4A) was investigated.

RESULTS

Fractionated irradiation of WISH-PC2 xenografts using total doses of >24 Gy induced a delay in tumor growth, while total doses of >36 Gy led to local tumor eradication. However, most of the irradiated mice suffered from disseminated metastases. Similarly, in the WM-4A xenograft, a total dose of 20 Gy led to tumor growth delay and some of the mice also developed metastases. Non-irradiated local xenografts failed to disseminate, even following surgical excision of the main tumor mass; however, tumor cells administered intravenously did form metastases. Metastases of both xenografts were located in the adrenal/kidney and inter-scapular regions, areas rich in brown adipose tissue. A correlation was found between the appearance of irradiation-induced metastases and activation of the gelatinase activity of matrix metalloproteinase-9.

CONCLUSIONS

Clinically, this study raises the possibility that radiation to SCCP may promote metastatic disease. For patients in whom prostate biopsy shows a predominance of small cell cancer, it may be necessary to deliver systemic therapy together with the radiotherapy in order to prevent the development of metastases.

Amplification of multiple genomic loci from single cells isolated by laser micro-dissection of tissues

BACKGROUND

Whole genome amplification (WGA) and laser assisted micro-dissection represent two recently developed technologies that can greatly advance biological and medical research. WGA allows the analysis of multiple genomic loci from a single genome and has been performed on single cells from cell suspensions and from enzymatically-digested tissues. Laser micro-dissection makes it possible to isolate specific single cells from heterogeneous tissues.

RESULTS

Here we applied for the first time WGA on laser micro-dissected single cells from stained tissue sections, and developed a protocol for sequentially performing the two procedures. The combined procedure allows correlating the cell's genome with its natural morphology and precise anatomical position. From each cell we amplified 122 genomic and mitochondrial loci. In cells obtained from fresh tissue sections, 64.5% of alleles successfully amplified to approximately 700000 copies each, and mitochondrial DNA was amplified successfully in all cells. Multiplex PCR amplification and analysis of cells from pre-stored sections yielded significantly poorer results. Sequencing and capillary electrophoresis of WGA products allowed detection of slippage mutations in microsatellites (MS), and point mutations in P53.

CONCLUSION

Comprehensive genomic analysis of single cells from stained tissue sections opens new research opportunities for cell lineage and depth analyses, genome-wide mutation surveys, and other single cell assays.