Adeno-associated viral vector serotype 9-based gene therapy for Niemann-Pick disease type A

Niemann-Pick disease type A (NPD-A) is a lysosomal storage disorder characterized by neurodegeneration and early death. It is caused by loss-of-function mutations in the gene encoding for acid sphingomyelinase (ASM), which hydrolyzes sphingomyelin into ceramide. Here, we evaluated the safety of cerebellomedullary (CM) cistern injection of adeno-associated viral vector serotype 9 encoding human ASM (AAV9-hASM) in nonhuman primates (NHP). We also evaluated its therapeutic benefit in a mouse model of the disease (ASM-KO mice). We found that CM injection in NHP resulted in widespread transgene expression within brain and spinal cord cells without signs of toxicity. CM injection in the ASM-KO mouse model resulted in hASM expression in cerebrospinal fluid and in different brain areas without triggering an inflammatory response. In contrast, direct cerebellar injection of AAV9-hASM triggered immune response. We also identified a minimally effective therapeutic dose for CM injection of AAV9-hASM in mice. Two months after administration, the treatment prevented motor and memory impairment, sphingomyelin (SM) accumulation, lysosomal enlargement, and neuronal death in ASM-KO mice. ASM activity was also detected in plasma from AAV9-hASM CM-injected ASM-KO mice, along with reduced SM amount and decreased inflammation in the liver. Our results support CM injection for future AAV9-based clinical trials in NPD-A as well as other lysosomal storage brain disorders.Nation Foundation and by grants from the Spanish Ministry of Economy and Competitivity (SAF-2014-57539-R and SAF2017-87698-R) to M.D.L. and from NIH-NINDS (R01NS073940) to K.S.B. A.P.-C. was a recipient of the FPU predoctoral fellowship from the Spanish Ministry of Economy and Competitivity and Fundación Ramón Areces to the Centro Biología Molecular Severo Ochoa

Engineering GPCR signaling pathways with RASSLs

We are creating families of designer G-protein-coupled receptors (GPCRs) to allow for precise spatiotemporal control of GPCR signaling in vivo. These engineered GPCRs, called receptors activated solely by synthetic ligands (RASSLs), are unresponsive to endogenous ligands but can be activated by nanomolar concentrations of pharmacologically inert, drug-like small molecules. Currently, RASSLs exist for the three major GPCR signaling pathways (Gs, Gi, Gq). These new advances are reviewed here to help facilitate the use of these powerful and diverse tools

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Functional Deactivation of the Major Neuronal Nicotinic Receptor Caused by Nicotine and a Protein Kinase C- Dependent Mechanism

SUMMARY The effect of nicotine on the major human neuronal nicotinic receptor (␣4␤2 subtype) was studied in permanently transfected HEK 293 cells. Prolonged exposure to low concentrations of nicotine (1 M) increased epibatidine binding but functionally deactivated the nicotinic receptor, abolishing Ca 2ϩ influx in response to an acute nicotine challenge. Deactivation could also be caused by down-regulating protein kinase C (PKC) activity with 0.5 M phorbol-12,13-dibutyrate or briefly incubating cells with the PKC inhibitor NPC-15437. Recovery from receptor deactivation caused by either nicotine treatment or PKC inhibition occurred slowly (4 -6 hr). Reversal of nicotineinduced deactivation was accelerated by the addition of inhibitors of protein phosphatases 2A and 2B. These data suggest a hypothetical mechanism of nicotine-induced deactivation that involves dephosphorylation of nicotinic receptors at PKC phosphorylation sites. The action of nicotine in the brain is mediated by a family of oligomeric ion channels whose opening is regulated by the binding of the neurotransmitter acetylcholine and drugs such as nicotine. Eleven different mammalian nAChR subunits (␣2-9 and ␤2-4) have been cloned (for reviews, see Refs. 1 and 2), and all the neuronal nicotinic receptors display a pronounced selectivity for Ca 2ϩ relative to Na ϩ (3-5). The most abundant receptor is composed of the ␣4 and ␤2 subunits with a stoichiometry of 2␣:3␤ (6) and is responsible for ϳ85% of the high affinity nicotine binding in the brain (6 -8). When nicotine is administered chronically to rats, a ϳ2-fold up-regulation of high affinity brain nicotinic receptors has been observed (9). This seems to be due to a dramatic decrease in the rate of degradation of the receptor in the cell membrane after nicotine treatment (10). The basis for this change in turnover is obscure. It has also been shown that chronic nicotine exposure leads to what has been termed "functional deactivation" of receptors to distinguish it from short term desensitization (11). Deactivation of neuronal nAChRs was first described and distinguished from receptor desensitization by Simasko et al. (12). The fact that chronic nicotine administration results in an increase in receptor number, coupled with a functional deactivation, suggests a mechanism for the addictive effects of nicotine (13). In this model, withdrawal of nicotine from an individual chronically exposed to the drug would result in reactivation of excess receptors, leading to craving, and prompting a further deactivating dose of the drug (13). Therefore, the relationship between nicotinic receptor number and intrinsic activity is a critical issue. In this report, we show that HEK 293 cells stably expressing the human ␣4␤2 nicotinic receptor subtype, after prolonged exposure to nicotine, display both a dramatic up-regulation of the receptor, together with a functional deactivation that is easily distinguished from simple short term desensitization. This functional deactivation can also be achieved by inhibition of PKC activity in the cells. Furthermore, phosphatase inhibitors increase the rate of recovery from nicotine-induced deactivation of the ␣4␤2 nicotinic receptor. Our data also indicate that the open state conformation per se, rather than calcium ion influx, directs formation of a deactivated receptor structure. Experimental Procedures Cloning human nicotinic receptor subunits. A human ␣4 subunit cDNA probe was generated by RT-PCR of total human brain RNA, with primers based on the rat ␣4 sequence. The resulting PCR fragment, which contained part of the human ␣4 sequence spanning nucleotides 755-985 (all numbering is from the ATG initiatio

Detection of Mycoplasma Infection of Mammalian Cells

Mycoplasma infection was detected in cultures of COS cells with a novel, simple assay that detects the conversion of arginine to citrulline by the enzyme, arginine deiminase, specific to all species of mycoplasma. Transfection of COS cells was inhibited in mycoplasma-infected cells, a phenomenon that was readily reversed by treatment with a mycoplasma removal agent. Cultures of cells used for transfection should be regularly monitored for evidence of mycoplasma by assay of arginine deiminase activity or by other methods

Strong Cortical and Spinal Cord Transduction After AAV7 and AAV9 Delivery into the Cerebrospinal Fluid of Nonhuman Primates

The present study builds on previous work showing that infusion of adeno-associated virus type 9 (AAV9) into the cisterna magna (CM) of nonhuman primates resulted in widespread transduction throughout cortex and spinal cord. Transduction efficiency was severely limited, however, by the presence of circulating anti-AAV antibodies. Accordingly, we compared AAV9 to a related serotype, AAV7, which has a high capsid homology. CM infusion of either AAV7 or AAV9 directed high level of cell transduction with similar patterns of distribution throughout brain cortex and along the spinal cord. Dorsal root ganglia and corticospinal tracts were also transduced. Both astrocytes and neurons were transduced. Interestingly, little transduction was observed in peripheral organs. Our results indicate that intrathecal delivery of either AAV7 or AAV9 directs a robust and widespread cellular transduction in the central nervous system and other peripheral neural structures

AAV9-mediated Expression of a Non-self Protein in Nonhuman Primate Central Nervous System Triggers Widespread Neuroinflammation Driven by Antigen-presenting Cell Transduction

Many studies have demonstrated that adeno-associated virus serotype 9 (AAV9) transduces astrocytes and neurons when infused into rat or nonhuman primate (NHP) brain. We previously showed in rats that transduction of antigen-presenting cells (APC) by AAV9 encoding a foreign protein triggered a full neurotoxic immune response. Accordingly, we asked whether this phenomenon occurred in NHP. We performed parenchymal or intrathecal infusion of AAV9 encoding green fluorescent protein (GFP), a non-self protein derived from jellyfish, or human aromatic L-amino acid decarboxylase (hAADC), a self-protein, in separate NHP. Animals receiving AAV9-GFP into cisterna magna (CM) became ataxic, indicating cerebellar pathology, whereas AAV9-hAADC animals remained healthy. In transduced regions, AAV9-GFP elicited inflammation associated with early activation of astrocytic and microglial cells, along with upregulation of major histocompatibility complex class II (MHC-II) in glia. In addition, we found Purkinje neurons lacking calbindin after AAV9-GFP but not after AAV9-hAADC delivery. Our results demonstrate that AAV9-mediated expression of a foreign-protein, but not self-recognized protein, triggers complete immune responses in NHP regardless of the route of administration. Our results warrant caution when contemplating use of serotypes that can transduce APC if the transgene is not syngeneic with the host. This finding has the potential to complicate preclinical toxicology studies in which such vectors encoding human cDNA's are tested in animals