Multiple sclerosis plasma IgG aggregates induce complement-dependent neuronal apoptosis

Grey matter pathology is central to the progression of multiple sclerosis (MS). We discovered that MS plasma immunoglobulin G (IgG) antibodies, mainly IgG1, form large aggregates (>100 nm) which are retained in the flow-through after binding to Protein A. Utilizing an annexin V live-cell apoptosis detection assay, we demonstrated six times higher levels of neuronal apoptosis induced by MS plasma IgG aggregates (n = 190, from two cohorts) compared to other neurological disorders (n = 116) and healthy donors (n = 44). MS IgG aggregate-mediated, complement-dependent neuronal apoptosis was evaluated in multiple model systems including primary human neurons, primary human astrocytes, neuroblastoma SH-SY5Y cells, and newborn mouse brain slices. Immunocytochemistry revealed the co-deposition of IgG, early and late complement activation products (C1q, C3b, and membrane attack complex C5b9), as well as active caspase 3 in treated neuronal cells. Furthermore, we found that MS plasma cytotoxic antibodies are not present in Protein G flow-through, nor in the paired plasma. The neuronal apoptosis can be inhibited by IgG depletion, disruption of IgG aggregates, pan-caspase inhibitor, and is completely abolished by digestion with IgG-cleaving enzyme IdeS. Transmission electron microscopy and nanoparticle tracking analysis revealed the sizes of MS IgG aggregates are greater than 100 nm. Our data support the pathological role of MS IgG antibodies and corroborate their connection to complement activation and axonal damage, suggesting that apoptosis may be a mechanism of neurodegeneration in MS.

DDRE-10. SCREENING OF EPIGENETIC COMPOUNDS IN GLIOMA AND GLIOBLASTOMA IDENTIFIES NOVEL THERAPEUTICS FOR THEIR POTENTIAL TREATMENT

BACKGROUND

28% of primary central nervous system tumors are glioma and glioblastoma. These tumors are responsible for 80% of malignant brain neoplasms and most brain tumor related deaths. Despite modern therapies, patients with grade II gliomas have an average survival of 8-15 years, while patients with grade III tumors have an average survival of 3-5 years, and patients with glioblastoma have an average survival of 12-15 months. The lack of a curative treatment for this group of tumors supports additional research and novel approaches to identify more effective therapies.

METHODS

In this study, we developed a high-throughput drug screen and culture system to identify epigenetic inhibitor compounds with the potential to reduce glioma and glioblastoma viability.

RESULTS

We screened 33 tumors: 18 glioblastoma, 8 oligodendroglioma, and 7 astrocytoma. The top three most effective compounds across the full glioma cohort were all HDAC inhibitors; in order from most effective: panobinostat (average tumor viability = 52.5% +/-14.1SD; p=2.16x10-61), LAQ824 (average tumor viability = 58.1% +/-18SD; p=1.48x10-45), and HC Toxin (average tumor viability = 64% +/-21.1SD; p= 1.16x10-33). Additionally, HDAC inhibition was also the most effective across each histopathological glioma type: astrocytoma, oligodendroglioma, and glioblastoma. UNC0631(G9a inhibitor) and JIB-04(KDM inhibitor) were the most effective compounds in the six recurrent tumors, though HDAC inhibition was still significantly effective in this group. We also evaluated drug sensitivity with respect to tumor grade, prior treatment, de novo vs progressive etiology, EGFR amplification, IDH mutation, MGMT methylation, and patient gender.

CONCLUSIONS

After screening a large glioma cohort against a panel of epigenetic inhibitors, we found HDAC inhibition most effectively reduced tumor viability across all histopathological types and grades. These findings require further in vivo validation.

DDRE-45. HIGH-THROUGHPUT SCREENING OF EPIGENETIC COMPOUNDS FOR THE TREATMENT OF CHORDOMA IDENTIFIES POTENTIAL NOVEL THERAPEUTICS

BACKGROUND

Chordoma is a rare malignant tumor with few treatment options. While surgical resection is deemed the most effective treatment, the 5-year overall survival rate is 61% and 5-year recurrence free survival rate is approximately 50%. To date, no FDA approved pharmacotherapies exist for the treatment of chordoma, and adjuvant therapy remains highly debated. This necessitates the need for further research to provide clinicians with more options to treat this patient population.

METHODS

In this study, we conducted a high-throughput 139-compound epigenetic inhibitor screen against 12 chordoma patient-derived cell lines; 4 were resected at our institution and 8 were graciously donated by the Chordoma Foundation.

RESULTS

8 tumors were located in the sacrum, 3 were located in the mobile spine, and 1 tumor was located in the clivus. 5 tumors were primary, 5 were recurrent, and 2 were metastatic. 6 tumors came from female patients and 6 tumors came from male patients. The top three most effect compounds across the cohort were the G9a inhibitor UNC0631 (cell viability = 64.5% +/-25.1SD; p=1.53x10-9), the KDM inhibitor JIB-04 (cell viability = 68.4% +/-27.2SD; p=9.81x10-8), and the G9a inhibitor BIX01294 (cell viability = 68.6% +/-27.9SD; p=1.27x10-7). No single compound significantly reduced viability in every tumor in the cohort, although the HDAC inhibitor HC Toxin significantly reduced viability in 9 tumors (cell viability = 69.7% +/-16.6SD; p=2.6x10-12). The most effective compound for sacral tumors was UNC0631 (viability = 68.6% +/-22.1SD; p=4x10-7), UNC0631 was also the most effective for spinal tumors (viability = 54.4% +/-32.1SD; p=2.72x10-3), and notably, no significant compounds were identified for the single clival tumor.

CONCLUSIONS

Based on our drug screen results, epigenetic inhibition, particularly methyltransferase inhibition, may be a promising therapeutic avenue for the treatment of chordomas.

EPCO-09. LONGITUDINAL ANALYSIS OF DIFFUSE GLIOMA REVEALS CELL STATE DYNAMICS AT RECURRENCE ASSOCIATED WITH CHANGES IN GENETICS AND THE MICROENVIRONMENT

Diffuse glioma is characterized by a poor prognosis and a universal resistance to therapy, though the evolutionary processes behind this resistance remain unclear. The Glioma Longitudinal Analysis (GLASS) Consortium has previously demonstrated that therapy-induced selective pressures shape the genetic evolution of glioma in a stochastic manner. However, single-cell studies have revealed that malignant glioma cells are highly plastic and transition their cell state in response to diverse challenges, including changes in the microenvironment and the administration of standard-of-care therapy. To interrogate the factors driving therapy resistance in diffuse glioma, we collected and analyzed RNA- and/or DNA-sequencing data from temporally separated tumor pairs of over 300 adult patients with IDH-wild-type or IDH-mutant glioma. In a subset of these tumor pairs, we complemented these data with single-nucleus RNAseq and multiplex imaging mass cytometry at each time point. Recurrent tumors exhibited diverse changes that were attributable to changes in histological features, somatic alterations, and microenvironment interactions. IDH-wild-type tumors overall were more invasive at recurrence and exhibited increased expression of neuronal signaling programs that reflected a possible role for neuronal interactions in promoting glioma progression. In contrast, recurrent IDH-mutant tumors exhibited a significant increase in proliferative expression programs that correlated with discrete genetic changes. Hypermutation and acquired CDKN2A homozygous deletions associated with an increase in proliferating stem-like malignant cells at recurrence in both glioma subtypes, reflecting active tumor expansion. A transition to the mesenchymal phenotype was associated with the presence of a specific myeloid cell state defined by unique ligand-receptor interactions with malignant cells, providing opportunities to target this transition through therapy. Collectively, our results uncover recurrence-associated changes in genetics and the microenvironment that can be targeted to shape disease progression following initial diagnosis.

DDRE-20. HIGH-THROUGHPUT SCREENING OF FDA-APPROVED COMPOUNDS IN GLIOMA AND GLIOBLASTOMA IDENTIFIES NOVEL THERAPEUTICS

BACKGROUND

Glioma and glioblastoma comprise 28% of all primary central nervous system tumors and cause the majority of primary brain tumor deaths. Despite substantial research into the molecular pathogenesis and genetic landscape of glioma, no currently approved therapies are curative for any glioma or glioblastoma. Patients with glioblastoma have an average survival time of 12-15 months, while patients with grade III gliomas have an average survival time of 3-5 years, and patients with grade II gliomas have an average survival time of 8-15 years. The lack of a curative treatment for these tumors necessitates additional research into novel therapies.

METHODS

In this study, we developed a high-throughput drug screen and culture system to identify existing FDA-approved therapies with the potential to inhibit glioma viability.

RESULTS

In total, we screened 39 tumors: 21 glioblastoma, 10 oligodendroglioma, and 8 astrocytoma. Carfilzomib was the most effective compound across the cohort, decreasing the average tumor viability to 39.0% +/- 16.5%SD. Regardless of tumor grade, MGMT methylation, EGFR amplification, tumor recurrence and etiology, tumor histology, prior treatment, and patient gender, carfilzomib significantly reduced cell viability in every tumor; though was not necessarily the most effective compound in each of these groups. We found HDAC inhibition to be the most effective treatment in grade 1 astrocytomas. However, HDAC inhibition was surpassed by carfilzomib and RNA transcription inhibitors in all higher grades. Interestingly, EGFR inhibition, while significantly effective in 36 tumors, was consistently less effective than carfilzomib across the cohort, though did surpass the effectiveness of HDAC inhibition in grade III gliomas.

CONCLUSIONS

FDA approved compounds can effectively inhibit glioma tumor viability. Specifically, carfilizomib holds great promise. Further in vivo studies are needed to confirm these findings.

DDRE-43. SCREENING OF FDA-APPROVED COMPOUNDS FOR THE TREATMENT OF CHORDOMA, WITH IN VIVO VALIDATION USING THREE DIFFERENT XENOGRAFT MODELS, IDENTIFIES BRIGATINIB AS A POTENTIAL TREATMENT

BACKGROUND

Chordoma is a rare malignant tumor with poor surgical control and no existing pharmacotherapies. Therefore, these tumors require additional research into novel therapeutics for their treatment.

METHODS

In this study we created a high-throughput drug screen and culture system to evaluate the efficacy of existing FDA-approved compounds in 10 chordoma cell lines and primary tumors. The cell lines were graciously donated by the Chordoma Foundation. Primary tumors were collected from our operating room. In vivo validation using three separate chordoma xenograft models was also performed through the Chordoma Foundation. One model was a primary clival pediatric tumor, the second was a metastatic sacral tumor, and the third model was a recurrent skull base tumor.

RESULTS

Using a 127 FDA-approved compound library, we screened 6 donated chordoma cell lines and 4 tumors resected from our institution. 5 of the chordomas were primary, 3 were recurrent, and 2 were metastatic. 6 chordoma were located in the sacrum, three were located in the mobile spine, and one was located in the clivus. Five tumors came from female patients and five came from male patients. After a single 72-hour 1um dose of brigatinib, the average tumor viability in our drug screen was reduced to 81.5% +/-9.5SD (p=1.61x10-13). In the in vivo studies, brigatinib achieved a full response in the metastatic sacral chordoma xenograft model (TGI=100%, p< 0.0001), a partial response in the recurrent skull base xenograft model (TGI=54%, p=0.3048), and no response in the primary clival pediatric xenograft model (TGI = 0%, p >0.9).

CONCLUSIONS

Brigatinib may be a viable treatment option for recurrent and metastatic chordomas.

NIMG-61. UNUSUAL PRESENTATION OF NEUROSARCOIDOSIS: A CASE SERIES

INTRODUCTION

Neurosarcoidosis is a rare diagnosis, and even with known systemic disease or history, often remains a diagnosis of exclusion. Typical imaging findings of neurosarcoidosis include white matter lesions coupled with meningeal enhancement, or “sugarcoating” near the skull base. Occasionally, imaging can be quite unusual and mimic other entities. Other diagnoses to rule out include neoplastic, autoimmune, or infectious pachymeningitis, neoplastic lesions, neurosyphilis or tuberculosis.

METHODS

Our neuropathology database was queried for neurosarcoidosis from January 2008 until December 2019. These cases were then reviewed for cases with unusual presentations for further review and discussion.

RESULTS

Here we present 16 cases of neurosarcoidosis with histories and/or imaging that did not conform to the typical appearance of neurosarcoidosis. Along with a rare radiographic presentation, these cases also lacked CSF, laboratory, or systemic findings to suggest a diagnosis of neurosarcoidosis. 15 of these cases presented intracranially while 1 case presented within the spinal cord.

CONCLUSIONS

Neurosarcoidosis presentations can vary greatly. A better understanding of some unique patient presentations can help improve noninvasive diagnosis, although biopsy often remains necessary for confirmation.

The genome of the simian and human malaria parasite Plasmodium knowlesi

Plasmodium knowlesi is an intracellular malaria parasite whose natural vertebrate host is Macaca fascicularis (the 'kra' monkey); however, it is now increasingly recognized as a significant cause of human malaria, particularly in southeast Asia. Plasmodium knowlesi was the first malaria parasite species in which antigenic variation was demonstrated, and it has a close phylogenetic relationship to Plasmodium vivax, the second most important species of human malaria parasite (reviewed in ref. 4). Despite their relatedness, there are important phenotypic differences between them, such as host blood cell preference, absence of a dormant liver stage or 'hypnozoite' in P. knowlesi, and length of the asexual cycle (reviewed in ref. 4). Here we present an analysis of the P. knowlesi (H strain, Pk1(A+) clone) nuclear genome sequence. This is the first monkey malaria parasite genome to be described, and it provides an opportunity for comparison with the recently completed P. vivax genome and other sequenced Plasmodium genomes. In contrast to other Plasmodium genomes, putative variant antigen families are dispersed throughout the genome and are associated with intrachromosomal telomere repeats. One of these families, the KIRs, contains sequences that collectively match over one-half of the host CD99 extracellular domain, which may represent an unusual form of molecular mimicry.

The "fatty pancreas allograft": anatomopathologic findings and clinical experience

Thirty-three hematoxylin and eosin-stained sections from 7 turned down pancreata from donors with body mass index (BMI) of 33.3 (range, 28-42) were examined. There was more fat infiltration between the superficial pancreatic lobules, interspersed with superficial islands of pancreatic tissue with its vessels and ductules. Thicker fatty interlobular septa were observed with numerous intralobular fat vacuoles. One organ had widespread autolysis. No microthrombi were noted. One pancreas from a 24-year-old donor with BMI of 30 was transplanted successfully. The "fatty pancreas" can be defatted and used for transplantation.

Genome sequence of the enterobacterial phytopathogen Erwinia carotovora subsp. atroseptica and characterization of virulence factors

The bacterial family Enterobacteriaceae is notable for its well studied human pathogens, including Salmonella, Yersinia, Shigella, and Escherichia spp. However, it also contains several plant pathogens. We report the genome sequence of a plant pathogenic enterobacterium, Erwinia carotovora subsp. atroseptica (Eca) strain SCRI1043, the causative agent of soft rot and blackleg potato diseases. Approximately 33% of Eca genes are not shared with sequenced enterobacterial human pathogens, including some predicted to facilitate unexpected metabolic traits, such as nitrogen fixation and opine catabolism. This proportion of genes also contains an overrepresentation of pathogenicity determinants, including possible horizontally acquired gene clusters for putative type IV secretion and polyketide phytotoxin synthesis. To investigate whether these gene clusters play a role in the disease process, an arrayed set of insertional mutants was generated, and mutations were identified. Plant bioassays showed that these mutants were significantly reduced in virulence, demonstrating both the presence of novel pathogenicity determinants in Eca, and the impact of functional genomics in expanding our understanding of phytopathogenicity in the Enterobacteriaceae.

Sequence of Plasmodium falciparum chromosomes 1, 3-9 and 13

Since the sequencing of the first two chromosomes of the malaria parasite, Plasmodium falciparum, there has been a concerted effort to sequence and assemble the entire genome of this organism. Here we report the sequence of chromosomes 1, 3-9 and 13 of P. falciparum clone 3D7--these chromosomes account for approximately 55% of the total genome. We describe the methods used to map, sequence and annotate these chromosomes. By comparing our assemblies with the optical map, we indicate the completeness of the resulting sequence. During annotation, we assign Gene Ontology terms to the predicted gene products, and observe clustering of some malaria-specific terms to specific chromosomes. We identify a highly conserved sequence element found in the intergenic region of internal var genes that is not associated with their telomeric counterparts.

Modulation of ACTH-induced grooming by [Des-Tyr1]-gamma-endorphin and haloperidol

Intraventricular administration of ACTH1-24 into the rat induced excessive grooming behavior. This response could be blocked by local administration of of neuroleptics into either the nucleus accumbens or the neostriatum. Local administration of [Des-Tyr1]-gamma-endorphine (LPH62-77) but not alpha-endorphin (LPH61-76) in either the nucleus accumbens or the neostriatum mimicked the effect of the neuroleptics. A second intraventricular injection of ACTH1-24 4 h after the first did not cause excessive grooming suggesting the development of acute tolerance. Both haloperidol and DT-gamma-E reduced the development of acute tolerance to ACTH-induced grooming. It is suggested the DT-gamma-E modulates the dopaminergic activity underlying the display of ACTH-induced excessive grooming.

New radioisotope test for detection of deep venous thrombosis in the legs

A radiopharmsceutical product, labelled macroaggregates of albumin (M.A.A.), which is in use as a lung scintiscanning agent has been noted to have an affinity for venous thrombi. With this material and an inexpensive portable scintillation detector we have attempted to diagnose and localize thrombi in leg veins. The procedure is performed at the bedside and the result is available in 30 minutes. Thirty-one patients with clinical evidence suggestive of deep venous thrombosis in the legs were studied by the radioisotope method and by phlebography. There was agreement in 18 of 21 legs shown to contain thrombus on phlebography and in 9 of 10 legs shown to be free of thrombosis on phlebography. There was, however, lesser agreement on the site of thrombosis between the two methods. The ease of performing the test combined with the rapidity of obtaining results and accuracy in diagnosis suggests that the test has a clinical application.