Showing papers in "Nature Medicine in 2008"

Amyloid-beta protein dimers isolated directly from Alzheimer's brains impair synaptic plasticity and memory.

Abstract: Alzheimer's disease constitutes a rising threat to public health. Despite extensive research in cellular and animal models, identifying the pathogenic agent present in the human brain and showing that it confers key features of Alzheimer's disease has not been achieved. We extracted soluble amyloid-beta protein (Abeta) oligomers directly from the cerebral cortex of subjects with Alzheimer's disease. The oligomers potently inhibited long-term potentiation (LTP), enhanced long-term depression (LTD) and reduced dendritic spine density in normal rodent hippocampus. Soluble Abeta from Alzheimer's disease brain also disrupted the memory of a learned behavior in normal rats. These various effects were specifically attributable to Abeta dimers. Mechanistically, metabotropic glutamate receptors were required for the LTD enhancement, and N-methyl D-aspartate receptors were required for the spine loss. Co-administering antibodies to the Abeta N-terminus prevented the LTP and LTD deficits, whereas antibodies to the midregion or C-terminus were less effective. Insoluble amyloid plaque cores from Alzheimer's disease cortex did not impair LTP unless they were first solubilized to release Abeta dimers, suggesting that plaque cores are largely inactive but sequester Abeta dimers that are synaptotoxic. We conclude that soluble Abeta oligomers extracted from Alzheimer's disease brains potently impair synapse structure and function and that dimers are the smallest synaptotoxic species.

Perfusion-decellularized matrix: using nature's platform to engineer a bioartificial heart

Abstract: About 3,000 individuals in the United States are awaiting a donor heart; worldwide, 22 million individuals are living with heart failure. A bioartificial heart is a theoretical alternative to transplantation or mechanical left ventricular support. Generating a bioartificial heart requires engineering of cardiac architecture, appropriate cellular constituents and pump function. We decellularized hearts by coronary perfusion with detergents, preserved the underlying extracellular matrix, and produced an acellular, perfusable vascular architecture, competent acellular valves and intact chamber geometry. To mimic cardiac cell composition, we reseeded these constructs with cardiac or endothelial cells. To establish function, we maintained eight constructs for up to 28 d by coronary perfusion in a bioreactor that simulated cardiac physiology. By day 4, we observed macroscopic contractions. By day 8, under physiological load and electrical stimulation, constructs could generate pump function (equivalent to about 2% of adult or 25% of 16-week fetal heart function) in a modified working heart preparation.

Interleukin-22 mediates early host defense against attaching and effacing bacterial pathogens

Abstract: Infections by attaching and effacing (A/E) bacterial pathogens, such as Escherichia coli O157:H7, pose a serious threat to public health. Using a mouse A/E pathogen, Citrobacter rodentium, we show that interleukin-22 (IL-22) has a crucial role in the early phase of host defense against C. rodentium. Infection of IL-22 knockout mice results in increased intestinal epithelial damage, systemic bacterial burden and mortality. We also find that IL-23 is required for the early induction of IL-22 during C. rodentium infection, and adaptive immunity is not essential for the protective role of IL-22 in this model. Instead, IL-22 is required for the direct induction of the Reg family of antimicrobial proteins, including RegIIIbeta and RegIIIgamma, in colonic epithelial cells. Exogenous mouse or human RegIIIgamma substantially improves survival of IL-22 knockout mice after C. rodentium infection. Together, our data identify a new innate immune function for IL-22 in regulating early defense mechanisms against A/E bacterial pathogens.

Lewy bodies in grafted neurons in subjects with Parkinson's disease suggest host-to-graft disease propagation.

Abstract: Two subjects with Parkinson's disease who had long-term survival of transplanted fetal mesencephalic dopaminergic neurons (11-16 years) developed alpha-synuclein-positive Lewy bodies in grafted neurons. Our observation has key implications for understanding Parkinson's pathogenesis by providing the first evidence, to our knowledge, that the disease can propagate from host to graft cells. However, available data suggest that the majority of grafted cells are functionally unimpaired after a decade, and recipients can still experience long-term symptomatic relief.

Stromal gene expression predicts clinical outcome in breast cancer

Abstract: Although it is increasingly evident that cancer is influenced by signals emanating from tumor stroma, little is known regarding how changes in stromal gene expression affect epithelial tumor progression. We used laser capture microdissection to compare gene expression profiles of tumor stroma from 53 primary breast tumors and derived signatures strongly associated with clinical outcome. We present a new stroma-derived prognostic predictor (SDPP) that stratifies disease outcome independently of standard clinical prognostic factors and published expression-based predictors. The SDPP predicts outcome in several published whole tumor-derived expression data sets, identifies poor-outcome individuals from multiple clinical subtypes, including lymph node-negative tumors, and shows increased accuracy with respect to previously published predictors, especially for HER2-positive tumors. Prognostic power increases substantially when the predictor is combined with existing outcome predictors. Genes represented in the SDPP reveal the strong prognostic capacity of differential immune responses as well as angiogenic and hypoxic responses, highlighting the importance of stromal biology in tumor progression.

Lewy body–like pathology in long-term embryonic nigral transplants in Parkinson's disease

Abstract: Fourteen years after transplantation into the striatum of an individual with Parkinson's disease, grafted nigral neurons were found to have Lewy body–like inclusions that stained positively for α-synuclein and ubiquitin and to have reduced immunostaining for dopamine transporter. These pathological changes suggest that Parkinson's disease is an ongoing process that can affect grafted cells in the striatum in a manner similar to host dopamine neurons in the substantia nigra. These findings have implications for cell-based therapies and for understanding the cause of Parkinson's disease.

Effective use of PI3K and MEK inhibitors to treat mutant Kras G12D and PIK3CA H1047R murine lung cancers

Abstract: Somatic mutations that activate phosphoinositide 3-kinase (PI3K) have been identified in the p110-alpha catalytic subunit (encoded by PIK3CA). They are most frequently observed in two hotspots: the helical domain (E545K and E542K) and the kinase domain (H1047R). Although the p110-alpha mutants are transforming in vitro, their oncogenic potential has not been assessed in genetically engineered mouse models. Furthermore, clinical trials with PI3K inhibitors have recently been initiated, and it is unknown if their efficacy will be restricted to specific, genetically defined malignancies. In this study, we engineered a mouse model of lung adenocarcinomas initiated and maintained by expression of p110-alpha H1047R. Treatment of these tumors with NVP-BEZ235, a dual pan-PI3K and mammalian target of rapamycin (mTOR) inhibitor in clinical development, led to marked tumor regression as shown by positron emission tomography-computed tomography, magnetic resonance imaging and microscopic examination. In contrast, mouse lung cancers driven by mutant Kras did not substantially respond to single-agent NVP-BEZ235. However, when NVP-BEZ235 was combined with a mitogen-activated protein kinase kinase (MEK) inhibitor, ARRY-142886, there was marked synergy in shrinking these Kras-mutant cancers. These in vivo studies suggest that inhibitors of the PI3K-mTOR pathway may be active in cancers with PIK3CA mutations and, when combined with MEK inhibitors, may effectively treat KRAS mutated lung cancers.

Expression of a noncoding RNA is elevated in Alzheimer's disease and drives rapid feed-forward regulation of β-secretase

Abstract: BACE is an enzyme necessary for the generation of neurotoxic amyloid-β in Alzheimer's disease. Claes Wahlestedt and his colleagues identify a noncoding RNA that is upregulated in the brains of individuals with Alzheimer's disase. This noncoding RNA increases expression of BACE, driving amyloid-β generation and possibly disease progression.

IL-22 mediates mucosal host defense against Gram-negative bacterial pneumonia

Abstract: Emerging evidence supports the concept that T helper type 17 (TH17) cells, in addition to mediating autoimmunity, have key roles in mucosal immunity against extracellular pathogens. Interleukin-22 (IL-22) and IL-17A are both effector cytokines produced by the TH17 lineage, and both were crucial for maintaining local control of the Gram-negative pulmonary pathogen, Klebsiella pneumoniae. Although both cytokines regulated CXC chemokines and granulocyte colony–stimulating factor production in the lung, only IL-22 increased lung epithelial cell proliferation and increased transepithelial resistance to injury. These data support the concept that the TH17 cell lineage and its effector molecules have evolved to effect host defense against extracellular pathogens at mucosal sites.

Virus-specific T cells engineered to coexpress tumor-specific receptors: persistence and antitumor activity in individuals with neuroblastoma

Abstract: Cytotoxic T lymphocytes (CTLs) directed to nonviral tumor-associated antigens do not survive long term and have limited antitumor activity in vivo, in part because such tumor cells typically lack the appropriate costimulatory molecules. We therefore engineered Epstein-Barr virus (EBV)-specific CTLs to express a chimeric antigen receptor directed to the diasialoganglioside GD2, a nonviral tumor-associated antigen expressed by human neuroblastoma cells. We reasoned that these genetically engineered lymphocytes would receive optimal costimulation after engagement of their native receptors, enhancing survival and antitumor activity mediated through their chimeric receptors. Here we show in individuals with neuroblastoma that EBV-specific CTLs expressing a chimeric GD2-specific receptor indeed survive longer than T cells activated by the CD3-specific antibody OKT3 and expressing the same chimeric receptor but lacking virus specificity. Infusion of these genetically modified cells seemed safe and was associated with tumor regression or necrosis in half of the subjects tested. Hence, virus-specific CTLs can be modified to function as tumor-directed effector cells.

Gene expression-based survival prediction in lung adenocarcinoma: a multi-site, blinded validation study.

Abstract: Although prognostic gene expression signatures for survival in early-stage lung cancer have been proposed, for clinical application, it is critical to establish their performance across different subject populations and in different laboratories. Here we report a large, training-testing, multi-site, blinded validation study to characterize the performance of several prognostic models based on gene expression for 442 lung adenocarcinomas. The hypotheses proposed examined whether microarray measurements of gene expression either alone or combined with basic clinical covariates (stage, age, sex) could be used to predict overall survival in lung cancer subjects. Several models examined produced risk scores that substantially correlated with actual subject outcome. Most methods performed better with clinical data, supporting the combined use of clinical and molecular information when building prognostic models for early-stage lung cancer. This study also provides the largest available set of microarray data with extensive pathological and clinical annotation for lung adenocarcinomas.

The miR-15a-miR-16-1 cluster controls prostate cancer by targeting multiple oncogenic activities.

Abstract: Two microRNAs, miR-15a and miR-16, localize to a chromosome region that is frequently deleted in cancer. Bonci et al. now show that these microRNAs have tumor suppressive effects in prostate cancer cells and regulate the expression of crucial oncogenic targets.

Simultaneous PET-MRI: a new approach for functional and morphological imaging

Abstract: Noninvasive imaging at the molecular level is an emerging field in biomedical research. This paper introduces a new technology synergizing two leading imaging methodologies: positron emission tomography (PET) and magnetic resonance imaging (MRI). Although the value of PET lies in its high-sensitivity tracking of biomarkers in vivo, it lacks resolving morphology. MRI has lower sensitivity, but produces high soft-tissue contrast and provides spectroscopic information and functional MRI (fMRI). We have developed a three-dimensional animal PET scanner that is built into a 7-T MRI. Our evaluations show that both modalities preserve their functionality, even when operated isochronously. With this combined imaging system, we simultaneously acquired functional and morphological PET-MRI data from living mice. PET-MRI provides a powerful tool for studying biology and pathology in preclinical research and has great potential for clinical applications. Combining fMRI and spectroscopy with PET paves the way for a new perspective in molecular imaging.

The actin cytoskeleton of kidney podocytes is a direct target of the antiproteinuric effect of cyclosporine A

Abstract: The immunosuppressive action of the calcineurin inhibitor cyclosporine A (CsA) stems from the inhibition of nuclear factor of activated T cells (NFAT) signaling in T cells. CsA is also used for the treatment of proteinuric kidney diseases. As it stands, the antiproteinuric effect of CsA is attributed to its immunosuppressive action. Here we show that the beneficial effect of CsA on proteinuria is not dependent on NFAT inhibition in T cells, but rather results from the stabilization of the actin cytoskeleton in kidney podocytes. CsA blocks the calcineurin-mediated dephosphorylation of synaptopodin, a regulator of Rho GTPases in podocytes, thereby preserving the phosphorylation-dependent synaptopodin-14-3-3 beta interaction. Preservation of this interaction, in turn, protects synaptopodin from cathepsin L-mediated degradation. These results represent a new view of calcineurin signaling and shed further light on the treatment of proteinuric kidney diseases. Novel calcineurin substrates such as synaptopodin may provide promising starting points for antiproteinuric drugs that avoid the serious side effects of long-term CsA treatment.

The biology of infertility: research advances and clinical challenges

Abstract: Reproduction is required for the survival of all mammalian species, and thousands of essential 'sex' genes are conserved through evolution. Basic research helps to define these genes and the mechanisms responsible for the development, function and regulation of the male and female reproductive systems. However, many infertile couples continue to be labeled with the diagnosis of idiopathic infertility or given descriptive diagnoses that do not provide a cause for their defect. For other individuals with a known etiology, effective cures are lacking, although their infertility is often bypassed with assisted reproductive technologies (ART), some accompanied by safety or ethical concerns. Certainly, progress in the field of reproduction has been realized in the twenty-first century with advances in the understanding of the regulation of fertility, with the production of over 400 mutant mouse models with a reproductive phenotype and with the promise of regenerative gonadal stem cells. Indeed, the past six years have witnessed a virtual explosion in the identification of gene mutations or polymorphisms that cause or are linked to human infertility. Translation of these findings to the clinic remains slow, however, as do new methods to diagnose and treat infertile couples. Additionally, new approaches to contraception remain elusive. Nevertheless, the basic and clinical advances in the understanding of the molecular controls of reproduction are impressive and will ultimately improve patient care.

Cyclophilin D deficiency attenuates mitochondrial and neuronal perturbation and ameliorates learning and memory in Alzheimer's disease.

Abstract: Mitochondrial dysfunction has been described in Alzheimer's disease, but how it is induced has remained unclear. Shi Du Yan and her colleagues find that a neurotoxic amyloid protein associated with the disease binds a mitochondrial protein called cyclophilin D and causes neuron death. The authors show that Alzheimer's disease model mice that lack cyclophilin D show improvements in learning and memory. Cyclophilin D (CypD, encoded by Ppif) is an integral part of the mitochondrial permeability transition pore, whose opening leads to cell death. Here we show that interaction of CypD with mitochondrial amyloid-β protein (Aβ) potentiates mitochondrial, neuronal and synaptic stress. The CypD-deficient cortical mitochondria are resistant to Aβ- and Ca2+-induced mitochondrial swelling and permeability transition. Additionally, they have an increased calcium buffering capacity and generate fewer mitochondrial reactive oxygen species. Furthermore, the absence of CypD protects neurons from Aβ- and oxidative stress–induced cell death. Notably, CypD deficiency substantially improves learning and memory and synaptic function in an Alzheimer's disease mouse model and alleviates Aβ-mediated reduction of long-term potentiation. Thus, the CypD-mediated mitochondrial permeability transition pore is directly linked to the cellular and synaptic perturbations observed in the pathogenesis of Alzheimer's disease. Blockade of CypD may be a therapeutic strategy in Alzheimer's disease.

Catapult-like release of mitochondrial DNA by eosinophils contributes to antibacterial defense

Abstract: Although eosinophils are considered useful in defense mechanisms against parasites, their exact function in innate immunity remains unclear. The aim of this study is to better understand the role of eosinophils within the gastrointestinal immune system. We show here that lipopolysaccharide from Gram-negative bacteria activates interleukin-5 (IL-5)- or interferon-gamma-primed eosinophils to release mitochondrial DNA in a reactive oxygen species-dependent manner, but independent of eosinophil death. Notably, the process of DNA release occurs rapidly in a catapult-like manner--in less than one second. In the extracellular space, the mitochondrial DNA and the granule proteins form extracellular structures able to bind and kill bacteria both in vitro and under inflammatory conditions in vivo. Moreover, after cecal ligation and puncture, Il5-transgenic but not wild-type mice show intestinal eosinophil infiltration and extracellular DNA deposition in association with protection against microbial sepsis. These data suggest a previously undescribed mechanism of eosinophil-mediated innate immune responses that might be crucial for maintaining the intestinal barrier function after inflammation-associated epithelial cell damage, preventing the host from uncontrolled invasion of bacteria.

Reversal of learning deficits in a Tsc2+/− mouse model of tuberous sclerosis

Abstract: Tuberous sclerosis is a single-gene disorder caused by heterozygous mutations in the TSC1 (9q34) or TSC2 (16p13.3) gene and is frequently associated with mental retardation, autism and epilepsy. Even individuals with tuberous sclerosis and a normal intelligence quotient (approximately 50%) are commonly affected with specific neuropsychological problems, including long-term and working memory deficits. Here we report that mice with a heterozygous, inactivating mutation in the Tsc2 gene (Tsc2(+/-) mice) show deficits in learning and memory. Cognitive deficits in Tsc2(+/-) mice emerged in the absence of neuropathology and seizures, demonstrating that other disease mechanisms are involved. We show that hyperactive hippocampal mammalian target of rapamycin (mTOR) signaling led to abnormal long-term potentiation in the CA1 region of the hippocampus and consequently to deficits in hippocampal-dependent learning. These deficits included impairments in two spatial learning tasks and in contextual discrimination. Notably, we show that a brief treatment with the mTOR inhibitor rapamycin in adult mice rescues not only the synaptic plasticity, but also the behavioral deficits in this animal model of tuberous sclerosis. The results presented here reveal a biological basis for some of the cognitive deficits associated with tuberous sclerosis, and they show that treatment with mTOR antagonists ameliorates cognitive dysfunction in a mouse model of this disorder.

Niemann-Pick disease type C1 is a sphingosine storage disease that causes deregulation of lysosomal calcium

Abstract: Niemann-Pick type C1 (NPC1) disease is a neurodegenerative lysosomal storage disorder caused by mutations in the acidic compartment (which we define as the late endosome and the lysosome) protein, NPC1. The function of NPC1 is unknown, but when it is dysfunctional, sphingosine, glycosphingolipids, sphingomyelin and cholesterol accumulate. We have found that NPC1-mutant cells have a large reduction in the acidic compartment calcium store compared to wild-type cells. Chelating luminal endocytic calcium in normal cells with high-affinity Rhod-dextran induced an NPC disease cellular phenotype. In a drug-induced NPC disease cellular model, sphingosine storage in the acidic compartment led to calcium depletion in these organelles, which then resulted in cholesterol, sphingomyelin and glycosphingolipid storage in these compartments. Sphingosine storage is therefore an initiating factor in NPC1 disease pathogenesis that causes altered calcium homeostasis, leading to the secondary storage of sphingolipids and cholesterol. This unique calcium phenotype represents a new target for therapeutic intervention, as elevation of cytosolic calcium with curcumin normalized NPC1 disease cellular phenotypes and prolonged survival of the NPC1 mouse.

The lysophosphatidic acid receptor LPA1 links pulmonary fibrosis to lung injury by mediating fibroblast recruitment and vascular leak.

Abstract: Aberrant wound-healing responses to injury have been implicated in the development of pulmonary fibrosis, but the mediators directing these pathologic responses have yet to be fully identified. We show that lysophosphatidic acid levels increase in bronchoalveolar lavage fluid following lung injury in the bleomycin model of pulmonary fibrosis, and that mice lacking one of its receptors, LPA1, are markedly protected from fibrosis and mortality in this model. The absence of LPA1 led to reduced fibroblast recruitment and vascular leak, two responses that may be excessive when injury leads to fibrosis rather than to repair, whereas leukocyte recruitment was preserved during the first week after injury. In persons with idiopathic pulmonary fibrosis, lysophosphatidic acid levels in bronchoalveolar lavage fluid were also increased, and inhibition of LPA1 markedly reduced fibroblast responses to the chemotactic activity of this fluid. LPA1 therefore represents a new therapeutic target for diseases in which aberrant responses to injury contribute to fibrosis, such as idiopathic pulmonary fibrosis.

Oxidative damage–induced inflammation initiates age-related macular degeneration

Abstract: Oxidative damage and inflammation are postulated to be involved in age-related macular degeneration (AMD). However, the molecular signal(s) linking oxidation to inflammation in this late-onset disease is unknown. Here we describe AMD-like lesions in mice after immunization with mouse serum albumin adducted with carboxyethylpyrrole, a unique oxidation fragment of docosahexaenoic acid that has previously been found adducting proteins in drusen from AMD donor eye tissues1 and in plasma samples2 from individuals with AMD. Immunized mice develop antibodies to this hapten, fix complement component-3 in Bruch's membrane, accumulate drusen below the retinal pigment epithelium during aging, and develop lesions in the retinal pigment epithelium mimicking geographic atrophy, the blinding end-stage condition characteristic of the dry form of AMD. We hypothesize that these mice are sensitized to the generation of carboxyethylpyrrole adducts in the outer retina, where docosahexaenoic acid is abundant and conditions for oxidative damage are permissive. This new model provides a platform for dissecting the molecular pathology of oxidative damage in the outer retina and the immune response contributing to AMD.

Kindlin-3 is essential for integrin activation and platelet aggregation

Abstract: Integrin-mediated platelet adhesion and aggregation are essential for sealing injured blood vessels and preventing blood loss, and excessive platelet aggregation can initiate arterial thrombosis, causing heart attacks and stroke1. To ensure that platelets aggregate only at injury sites, integrins on circulating platelets exist in a low-affinity state and shift to a high-affinity state (in a process known as integrin activation or priming) after contacting a wounded vessel2. The shift is mediated through binding of the cytoskeletal protein Talin to the β subunit cytoplasmic tail3,4,5. Here we show that platelets lacking the adhesion plaque protein Kindlin-3 cannot activate integrins despite normal Talin expression. As a direct consequence, Kindlin-3 deficiency results in severe bleeding and resistance to arterial thrombosis. Mechanistically, Kindlin-3 can directly bind to regions of β-integrin tails distinct from those of Talin and trigger integrin activation. We have therefore identified Kindlin-3 as a novel and essential element for platelet integrin activation in hemostasis and thrombosis.

Granulysin is a key mediator for disseminated keratinocyte death in Stevens-Johnson syndrome and toxic epidermal necrolysis

Abstract: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse drug reactions characterized by massive epidermal necrosis, in which the specific danger signals involved remain unclear. Here we show that blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule, confirmed by quantitative PCR and immunohistochemistry. Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity. Granulysin in the blister fluids was a 15-kDa secretory form, and injection of it into mouse skin resulted in features mimicking SJS-TEN. Our findings demonstrate that secretory granulysin is a key molecule responsible for the disseminated keratinocyte death in SJS-TEN and highlight a mechanism for CTL- or NK cell—mediated cytotoxicity that does not require direct cellular contact. Adverse drug reactions (ADRs) account for 6–7% of all hospital admissions and remain a major clinical problem 1 . Among them, SJS

Recovery of supraspinal control of stepping via indirect propriospinal relay connections after spinal cord injury.

Abstract: Spinal cord injuries (SCIs) in humans and experimental animals are often associated with varying degrees of spontaneous functional recovery during the first months after injury. Such recovery is widely attributed to axons spared from injury that descend from the brain and bypass incomplete lesions, but its mechanisms are uncertain. To investigate the neural basis of spontaneous recovery, we used kinematic, physiological and anatomical analyses to evaluate mice with various combinations of spatially and temporally separated lateral hemisections with or without the excitotoxic ablation of intrinsic spinal cord neurons. We show that propriospinal relay connections that bypass one or more injury sites are able to mediate spontaneous functional recovery and supraspinal control of stepping, even when there has been essentially total and irreversible interruption of long descending supraspinal pathways in mice. Our findings show that pronounced functional recovery can occur after severe SCI without the maintenance or regeneration of direct projections from the brain past the lesion and can be mediated by the reorganization of descending and propriospinal connections. Targeting interventions toward augmenting the remodeling of relay connections may provide new therapeutic strategies to bypass lesions and restore function after SCI and in other conditions such as stroke and multiple sclerosis.

Distinct roles of matrix metalloproteases in the early- and late-phase development of neuropathic pain

Abstract: Treatment of neuropathic pain, triggered by multiple insults to the nervous system, is a clinical challenge because the underlying mechanisms of neuropathic pain development remain poorly understood. Most treatments do not differentiate between different phases of neuropathic pain pathophysiology and simply focus on blocking neurotransmission, producing transient pain relief. Here, we report that early- and late-phase neuropathic pain development in rats and mice after nerve injury require different matrix metalloproteinases (MMPs). After spinal nerve ligation, MMP-9 shows a rapid and transient upregulation in injured dorsal root ganglion (DRG) primary sensory neurons consistent with an early phase of neuropathic pain, whereas MMP-2 shows a delayed response in DRG satellite cells and spinal astrocytes consistent with a late phase of neuropathic pain. Local inhibition of MMP-9 by an intrathecal route inhibits the early phase of neuropathic pain, whereas inhibition of MMP-2 suppresses the late phase of neuropathic pain. Further, intrathecal administration of MMP-9 or MMP-2 is sufficient to produce neuropathic pain symptoms. After nerve injury, MMP-9 induces neuropathic pain through interleukin-1beta cleavage and microglial activation at early times, whereas MMP-2 maintains neuropathic pain through interleukin-1beta cleavage and astrocyte activation at later times. Inhibition of MMP may provide a novel therapeutic approach for the treatment of neuropathic pain at different phases.

Broadly neutralizing antibodies protect against hepatitis C virus quasispecies challenge

Abstract: A major problem in hepatitis C virus (HCV) immunotherapy or vaccine design is the extreme variability of the virus. We identified human monoclonal antibodies (mAbs) that neutralize genetically diverse HCV isolates and protect against heterologous HCV quasispecies challenge in a human liver-chimeric mouse model. The results provide evidence that broadly neutralizing antibodies to HCV protect against heterologous viral infection and suggest that a prophylactic vaccine against HCV may be achievable.

Ex vivo glycan engineering of CD44 programs human multipotent mesenchymal stromal cell trafficking to bone

Abstract: The capacity to direct migration ('homing') of blood-borne cells to a predetermined anatomic compartment is vital to stem cell-based tissue engineering and other adoptive cellular therapies. Although multipotent mesenchymal stromal cells (MSCs, also termed 'mesenchymal stem cells') hold the potential for curing generalized skeletal diseases, their clinical effectiveness is constrained by the poor osteotropism of infused MSCs (refs. 1-3). Cellular recruitment to bone occurs within specialized marrow vessels that constitutively express vascular E-selectin, a lectin that recognizes sialofucosylated determinants on its various ligands. We show here that human MSCs do not express E-selectin ligands, but express a CD44 glycoform bearing alpha-2,3-sialyl modifications. Using an alpha-1,3-fucosyltransferase preparation and enzymatic conditions specifically designed for treating live cells, we converted the native CD44 glycoform on MSCs into hematopoietic cell E-selectin/L-selectin ligand (HCELL), which conferred potent E-selectin binding without effects on cell viability or multipotency. Real-time intravital microscopy in immunocompromised (NOD/SCID) mice showed that intravenously infused HCELL(+) MSCs infiltrated marrow within hours of infusion, with ensuing rare foci of endosteally localized cells and human osteoid generation. These findings establish that the HCELL glycoform of CD44 confers tropism to bone and unveil a readily translatable roadmap for programming cellular trafficking by chemical engineering of glycans on a distinct membrane glycoprotein.

Chip–NMR biosensor for detection and molecular analysis of cells

Abstract: Rapid and accurate measurement of biomarkers in tissue and fluid samples is a major challenge in medicine. Here we report the development of a new, miniaturized diagnostic magnetic resonance (DMR) system for multiplexed, quantitative and rapid analysis. By using magnetic particles as a proximity sensor to amplify molecular interactions, the handheld DMR system can perform measurements on unprocessed biological samples. We show the capability of the DMR system by using it to detect bacteria with high sensitivity, identify small numbers of cells and analyze them on a molecular level in real time, and measure a series of protein biomarkers in parallel. The DMR technology shows promise as a robust and portable diagnostic device.

BMP type I receptor inhibition reduces heterotopic ossification

Abstract: Fibrodysplasia ossificans progressiva (FOP) is a congenital disorder of progressive and widespread postnatal ossification of soft tissues and is without known effective treatments. Affected individuals harbor conserved mutations in the ACVR1 gene that are thought to cause constitutive activation of the bone morphogenetic protein (BMP) type I receptor, activin receptor-like kinase-2 (ALK2). Here we show that intramuscular expression in the mouse of an inducible transgene encoding constitutively active ALK2 (caALK2), resulting from a glutamine to aspartic acid change at amino acid position 207, leads to ectopic endochondral bone formation, joint fusion and functional impairment, thus phenocopying key aspects of human FOP. A selective inhibitor of BMP type I receptor kinases, LDN-193189 (ref. 6), inhibits activation of the BMP signaling effectors SMAD1, SMAD5 and SMAD8 in tissues expressing caALK2 induced by adenovirus specifying Cre (Ad.Cre). This treatment resulted in a reduction in ectopic ossification and functional impairment. In contrast to localized induction of caALK2 by Ad.Cre (which entails inflammation), global postnatal expression of caALK2 (induced without the use of Ad.Cre and thus without inflammation) does not lead to ectopic ossification. However, if in this context an inflammatory stimulus was provided with a control adenovirus, ectopic bone formation was induced. Like LDN-193189, corticosteroid inhibits ossification in Ad.Cre-injected mutant mice, suggesting caALK2 expression and an inflammatory milieu are both required for the development of ectopic ossification in this model. These results support the role of dysregulated ALK2 kinase activity in the pathogenesis of FOP and suggest that small molecule inhibition of BMP type I receptor activity may be useful in treating FOP and heterotopic ossification syndromes associated with excessive BMP signaling.

Differential regulation of central nervous system autoimmunity by TH1 and TH17 cells

Abstract: Multiple sclerosis is an inflammatory, demyelinating disease of the central nervous system (CNS) characterized by a wide range of clinical signs1 The location of lesions in the CNS is variable and is a crucial determinant of clinical outcome Multiple sclerosis is believed to be mediated by myelin-specific T cells, but the mechanisms that determine where T cells initiate inflammation are unknown Differences in lesion distribution have been linked to the HLA complex, suggesting that T cell specificity influences sites of inflammation2 We demonstrate that T cells that are specific for different myelin epitopes generate populations characterized by different T helper type 17 (TH17) to T helper type 1 (TH1) ratios depending on the functional avidity of interactions between TCR and peptide-MHC complexes Notably, the TH17:TH1 ratio of infiltrating T cells determines where inflammation occurs in the CNS Myelin-specific T cells infiltrate the meninges throughout the CNS, regardless of the TH17:TH1 ratio However, T cell infiltration and inflammation in the brain parenchyma occurs only when TH17 cells outnumber TH1 cells and trigger a disproportionate increase in interleukin-17 expression in the brain In contrast, T cells showing a wide range of TH17:TH1 ratios induce spinal cord parenchymal inflammation These findings reveal critical differences in the regulation of inflammation in the brain and spinal cord