Repurposing drugs for the treatment of osteoarthritis.

OBJECTIVE: Currently, no disease-modifying therapies for osteoarthritis (OA) exist, and attempts to identify novel cellular targets have been challenging. Risk factors for OA include advanced age, obesity, and metabolic syndrome. This creates an attractive opportunity to repurpose existing drugs that are used to treat comorbidities commonly encountered in patients with OA, if those drugs possess OA disease modifying properties. METHODS: This narrative review incorporates findings from knee or hand OA randomized clinical trials, post-hoc clinical trial analyses, prospective cohort studies, and observational data. RESULTS: Drugs used for the treatment of rheumatoid arthritis (methotrexate; TNFa, IL-1, and IL-6 pathway inhibitors; hydroxychloroquine), atopic/allergic disease (anti-histamines), osteoporosis (bisphosphonates and vitamin D), type 2 diabetes (metformin and GLP-1 agonists), and cardiovascular disease (atorvastatin, fish oil, and beta blockers) were reviewed for their potential benefit in OA. This review outlines the successful attributes of repurposed drugs, the challenges in repurposing drugs, and strategies for future clinical trials to support OA drug repurposing. Potential drug candidates for OA may be identified through the use of existing datasets and via collaborations with researchers in other fields to include OA endpoints in future clinical trials. CONCLUSION: Given the association of OA with several commonly treated comorbidities, drug repurposing is an appealing approach that could provide a favorable benefit-to-risk ratio for chronic OA treatment.

Genetic association between atopic disease and osteoarthritis.

OBJECTIVES: To evaluate the association between genetically determined risk for atopic disease and osteoarthritis (OA). METHODS: We performed linkage disequilibrium (LD) score regression using 1000 Genomes Project European samples as a reference for patterns of genome-wide LD. Summary statistics for atopic disease traits were obtained from the UK Biobank. We generated a pairwise genetic correlation between OA and traits for atopic disease to estimate the genetic correlation between traits (rg) and heritability for each trait. The association between atopy-related traits and OA was examined using Mendelian randomization (MR) on summary statistics; we reported inverse-variance weighted (IVW), MR-Egger, maximum likelihood estimation, weighted median, and weighted mode. RESULTS: There was a significant positive correlation between the genome-wide genetic architecture of asthma and all OA traits. Using the IVW (random effects), there was a significant association between asthma and knee OA ((odds ratio) OR = 1.04, 95% (confidence interval) CI 1.01-1.08, p = 0.0169). Using IVW (fixed effects), significant associations were identified between knee OA and allergic disease (OR = 1.07, 95% CI 1.01-1.14, p = 0.0342), allergic rhinitis (OR = 1.07, 95% CI 1.00-1.13, p = 0.0368), and asthma (OR = 1.04, 95% CI 1.01-1.07, p = 0.0139), as well as for OA at any site and asthma (OR = 1.02, 95% CI 1.00-1.04, p = 0.0166). CONCLUSIONS: We found a significant correlation between the overall genetic architecture of asthma and OA, as well as an increased risk of developing OA in patients with genetic variants associated with asthma and allergic rhinitis; predominately, this risk was for the development of knee OA. These results support a causal relationship between asthma and/or allergic rhinitis and knee OA.

Abundant transcriptomic alterations in the human cerebellum of patients with a C9orf72 repeat expansion.

The most prominent genetic cause of both amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) is a repeat expansion in the gene C9orf72. Importantly, the transcriptomic consequences of the C9orf72 repeat expansion remain largely unclear. Here, we used short-read RNA sequencing (RNAseq) to profile the cerebellar transcriptome, detecting alterations in patients with a C9orf72 repeat expansion. We focused on the cerebellum, since key C9orf72-related pathologies are abundant in this neuroanatomical region, yet TDP-43 pathology and neuronal loss are minimal. Consistent with previous work, we showed a reduction in the expression of the C9orf72 gene and an elevation in homeobox genes, when comparing patients with the expansion to both patients without the C9orf72 repeat expansion and control subjects. Interestingly, we identified more than 1000 alternative splicing events, including 4 in genes previously associated with ALS and/or FTLD. We also found an increase of cryptic splicing in C9orf72 patients compared to patients without the expansion and controls. Furthermore, we demonstrated that the expression level of select RNA-binding proteins is associated with cryptic splice junction inclusion. Overall, this study explores the presence of widespread transcriptomic changes in the cerebellum, a region not confounded by severe neurodegeneration, in post-mortem tissue from C9orf72 patients.

Senile plaque-associated transactive response DNA-binding protein 43 in Alzheimer's disease: A case report spanning 16 years of memory loss.

Transactive response DNA-binding protein 43 (TDP-43) pathological inclusions are found in frontotemporal lobar degeneration (FTLD-TDP) and Alzheimer's disease (AD-TDP). While clinically different, TDP-43 inclusions in FTLD-TDP and AD can have similar morphological characteristics. However, TDP-43 colocalizing with tau and forming "apple-bite" or "flame-shaped" neuronal cytoplasmic inclusions (NCI) are only found in AD-TDP. Here, we describe a case with AD and neuritic plaque-associated TDP-43. The patient was a 96-year-old right-handed Caucasian woman who had developed a slowly progressive amnestic syndrome compatible with typical AD at age 80. Genetic testing revealed APOE ε3/ε4, GRN r5848 CT, and MAPT H1/H2 genotype. Consistent with the old age at onset and long disease duration, limbic-predominant AD was found at autopsy, with high hippocampal yet low cortical neurofibrillary tangle (NFT) counts. Hippocampal and amygdala sclerosis were present. Immunohistochemistry for phospho-TDP-43 showed NCIs, dystrophic neurites, and rare neuronal intranuclear inclusions consistent with FTLD-TDP type A, as well as tau NFT-associated TDP-43 inclusions. These were frequent in the amygdala, entorhinal cortex, hippocampus, occipitotemporal gyrus, and inferior temporal gyrus but sparse in the mid-frontal cortex. Additionally, there were TDP-43-immunoreactive inclusions forming plaque-like structures in the molecular layer of the dentate fascia of the hippocampus. The presence of neuritic plaques in the same region was confirmed using thioflavin-S fluorescent microscopy and immunohistochemistry for phospho-tau. Double labeling immunofluorescence showed colocalization of TDP-43 and tau within neuritic plaques. Other pathologies included mild Lewy body pathology predominantly affecting the amygdala and olfactory bulb, aging-related tau astrogliopathy, and mixed small vessel disease (arteriolosclerosis and amyloid angiopathy) with several cortical microinfarcts. In conclusion, we have identified TDP-43 colocalizing with tau in neuritic plaques in AD, which expands the association of TDP-43 and tau in AD beyond NFTs. The clinical correlate of this plaque-associated TDP-43 appears to be a slowly progressive amnestic syndrome.

Increased risk of osteoarthritis in patients with atopic disease.

OBJECTIVES: To determine the incidence of osteoarthrits (OA) in patients with atopic disease compared with matched non-exposed patients. METHODS: We conducted a retrospective cohort study with propensity score matching using claims data from Optum's de-identified Clinformatics Data Mart (CDM) (January 2003 to June 2019) and electronic health record data from the Stanford Research Repository (STARR) (January 2010 to December 2020). We included adult patients without pre-existing OA or inflammatory arthritis who were exposed to atopic disease or who were non-exposed. The primary outcome was the development of incident OA. RESULTS: In Optum CDM, we identified 117 346 exposed patients with asthma or atopic dermatitis (mean age 52 years; 60% female) and 1 247 196 non-exposed patients (mean age 50 years; 48% female). After propensity score matching (n=1 09 899 per group), OA incidence was higher in patients with asthma or atopic dermatitis (26.9 per 1000 person-years) compared with non-exposed patients (19.1 per 1000 person-years), with an adjusted odds ratio (aOR) of 1.58 (95% CI 1.55 to 1.62) for developing OA. This effect was even more pronounced in patients with both asthma and atopic dermatitis compared with non-exposed patients (aOR=2.15; 95% CI 1.93 to 2.39) and in patients with asthma compared with patients with chronic obstructive pulmonary disease (aOR=1.83; 95% CI 1.73 to 1.95). We replicated our results in an independent dataset (STARR), which provided the added richness of body mass index data. The aOR of developing OA in patients with asthma or atopic dermatitis versus non-exposed patients in STARR was 1.42 (95% CI 1.36 to 1.48). CONCLUSIONS: This study demonstrates an increased incidence of OA in patients with atopic disease. Future interventional studies may consider targeting allergic pathways for the prevention or treatment of OA.

A double-blind, placebo-controlled, randomized withdrawal trial of sarilumab for the treatment of glucocorticoid-dependent sarcoidosis.

OBJECTIVES: Effective steroid-sparing therapies for the treatment of sarcoidosis are lacking; interleukin-6 (IL-6) antagonists may reduce sarcoidosis disease activity. This study assessed the safety and efficacy of the IL-6 receptor antagonist, sarilumab, in subjects with glucocorticoid-dependent sarcoidosis. METHODS: This phase II, double-blind, placebo-controlled, randomized withdrawal trial enrolled 15 subjects with biopsy-proven sarcoidosis at Stanford University from November 2019 to September 2022. In Period 1, subjects were treated with open-label sarilumab 200mg subcutaneously every two weeks for 16 weeks, with predefined tapering of prednisone. Subjects who completed Period 1 without a sarcoidosis flare entered Period 2 and were randomized to continue sarilumab or to receive matching placebo for 12 weeks. Endpoints included flare-free survival, as well as changes in pulmonary function tests, chest imaging, patient reported outcomes, and laboratory values. RESULTS: Fifteen subjects were enrolled in the study (median age 57 years, 80% male, 73.3% White), and 10 subjects successfully completed Period 1. During Period 1, 4 of 15 subjects (26.7%) discontinued due to worsening of their sarcoidosis, and CT chest imaging worsened in 5 of 15 subjects (35.7%). During Period 2, 0 of 2 subjects in the sarilumab group and 1 of 8 subjects (12.5%) in the placebo group had a flare. Treatment with sarilumab 200 mg was generally well tolerated in subjects with sarcoidosis. CONCLUSION: In this double-blind, placebo-controlled, randomized withdrawal trial, a meaningful signal for improvement in subjects with sarcoidosis treated with sarilumab was not observed. Given the small numbers in this study, no definitive conclusions can be drawn. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04008069.

The Positive Predictive Value of a Very High Serum IgG4 Concentration for the Diagnosis of IgG4-Related Disease.

OBJECTIVE: Serum IgG4 concentrations are used to evaluate a diagnosis of IgG4-related disease (IgG4-RD), but the positive predictive value (PPV) of a very high IgG4 level is uncertain. This study evaluated the PPV of a very high IgG4 concentration for diagnosing IgG4-RD. METHODS: The data warehouses of 2 large academic healthcare systems were queried for IgG4 concentration test results. Cases with serum IgG4 concentrations > 5× the upper limit of normal (ULN) were included. Cases of IgG4-RD were determined using the American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria. The PPV for IgG4-RD of an IgG4 concentration > 5× ULN was estimated. Other conditions associated with very high IgG4 concentrations and specific features of IgG4-RD cases were characterized. RESULTS: IgG4 concentrations were available in 32,206 cases. Of these, 3039 (9.4%) had elevated IgG4 concentrations, and a final cohort of 191 (0.6%) cases had IgG4 concentrations > 5× ULN (median age 66 yrs, 72% male). The PPV of an IgG4 concentration > 5× ULN for a diagnosis of IgG4-RD was 75.4% (95% CI 68.7-81.3). In the remaining cases, elevated IgG4 concentrations were observed among patients with malignancies, autoimmune diseases, and infections. CONCLUSION: The majority of cases with serum IgG4 concentrations > 5× ULN in this study had IgG4-RD. These data support the high weight placed on very high serum IgG4 concentrations in the ACR/EULAR classification criteria. However, 25% of cases with very high IgG4 concentrations had an alternative diagnosis, underscoring the importance of considering the broad differential of etiologies associated with an elevated IgG4 concentration when evaluating a patient.

Shared brain transcriptomic signature in TDP-43 type A FTLD patients with or without GRN mutations.

Frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) is a complex heterogeneous neurodegenerative disorder for which mechanisms are poorly understood. To explore transcriptional changes underlying FTLD-TDP, we performed RNA-sequencing on 66 genetically unexplained FTLD-TDP patients, 24 FTLD-TDP patients with GRN mutations and 24 control participants. Using principal component analysis, hierarchical clustering, differential expression and coexpression network analyses, we showed that GRN mutation carriers and FTLD-TDP-A patients without a known mutation shared a common transcriptional signature that is independent of GRN loss-of-function. After combining both groups, differential expression as compared to the control group and coexpression analyses revealed alteration of processes related to immune response, synaptic transmission, RNA metabolism, angiogenesis and vesicle-mediated transport. Deconvolution of the data highlighted strong cellular alterations that were similar in FTLD-TDP-A and GRN mutation carriers with NSF as a potentially important player in both groups. We propose several potentially druggable pathways such as the GABAergic, GDNF and sphingolipid pathways. Our findings underline new disease mechanisms and strongly suggest that affected pathways in GRN mutation carriers extend beyond GRN and contribute to genetically unexplained forms of FTLD-TDP-A.

Neutralizing anti-IL-1 receptor antagonist autoantibodies induce inflammatory and fibrotic mediators in IgG4-related disease.

BACKGROUND: IgG4-related disease (IgG4-RD) is a fibroinflammatory condition involving loss of B-cell tolerance and production of autoantibodies. However, the relevant targets and role of these aberrant humoral immune responses are not defined. OBJECTIVE: Our aim was to identify novel autoantibodies and autoantigen targets that promote pathogenic responses in IgG4-RD. METHODS: We sequenced plasmablast antibody repertoires in patients with IgG4-RD. Representative mAbs were expressed and their specificities characterized by using cytokine microarrays. The role of anti-IL-1 receptor antagonist (IL-1RA) autoantibodies was investigated by using in vitro assays. RESULTS: We identified strong reactivity against human IL-1RA by using a clonally expanded plasmablast-derived mAb from a patient with IgG4-RD. Plasma from patients with IgG4-RD exhibited elevated levels of reactivity against IL-1RA compared with plasma from the controls and neutralized IL-1RA activity, resulting in inflammatory and fibrotic mediator production in vitro. IL-1RA was detected in lesional tissues from patients with IgG4-RD. Patients with anti-IL-1RA autoantibodies of the IgG4 subclass had greater numbers of organs affected than did those without anti-IL-1RA autoantibodies. Peptide analyses identified IL-1RA epitopes targeted by anti-IL-1RA antibodies at sites near the IL-1RA/IL-1R interface. Serum from patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) also had elevated levels of anti-IL-1RA autoantibodies compared with those of the controls. CONCLUSION: A subset of patients with IgG4-RD have anti-IL-1RA autoantibodies, which promote proinflammatory and profibrotic meditator production via IL-1RA neutralization. These findings support a novel immunologic mechanism underlying the pathogenesis of IgG4-RD. Anti-IL-1RA autoantibodies are also present in a subset of patients with SLE and RA, suggesting a potential common pathway in multiple autoimmune diseases.

Evolution of the Chief Medical Officer Role in Teaching Hospitals and Health Systems.

GOAL: Clinical physician leaders have become an increasingly important asset to hospitals and hospital systems in a changing healthcare environment. Specifically, the role of the chief medical officer (CMO) has expanded and evolved amid the shift to value-based payment models and sharpened focus on patient safety, quality, community engagement, and equity in healthcare, as well as a global pandemic. In light of these changes, this study examined the transformation of CMOs and similar roles and evaluated the current needs, challenges, and responsibilities of clinical leaders today. METHODS: The primary data source used in this analysis was a survey fielded to 391 clinical leaders in 290 Association of American Medical Colleges-member hospitals and health systems in 2020. In addition, this study compared responses to the 2020 survey with findings from two prior iterations of the survey from 2005 and 2016. The surveys collected information regarding demographics, compensation, administrative titles, qualifications for the position, and the scope of the role, among other questions. All surveys consisted of multiple-choice, free response, and rating questions. The analysis was conducted using frequency counts and percentage distributions. PRINCIPAL FINDINGS: Thirty percent of eligible clinical leaders responded to the 2020 survey. Twenty-six percent of the clinical leader respondents identified as female. Ninety-one percent of the CMOs were members of the senior management team in their hospital or health system. CMOs reported that they were responsible for five hospitals, on average, with 67% indicating they were responsible for more than 500 physicians. PRACTICAL APPLICATIONS: This analysis provides hospital and health systems with insight into the expanding scope and complexity of CMOs as they take on greater leadership responsibilities within their institutions amidst a shifting healthcare landscape. In reflecting on our results, hospital leaders can understand the current needs, barriers, and responsibilities of today's clinical leaders.

Concurrent tau pathologies in frontotemporal lobar degeneration with TDP-43 pathology.

AIMS: Accumulating evidence suggests that patients with frontotemporal lobar degeneration (FTLD) can have pathologic accumulation of multiple proteins, including tau and TDP-43. This study aimed to determine the frequency and characteristics of concurrent tau pathology in FTLD with TDP-43 pathology (FTLD-TDP). METHODS: The study included 146 autopsy-confirmed cases of FTLD-TDP and 55 cases of FTLD-TDP with motor neuron disease (FTLD-MND). Sections from the basal forebrain were screened for tau pathology with phosphorylated-tau immunohistochemistry. For cases with tau pathology on the screening section, additional brain sections were studied to establish a diagnosis. Genetic analysis of C9orf72, GRN and MAPT was performed on select cases. RESULTS: We found 72 cases (36%) with primary age-related tauopathy (PART), 85 (42%) with ageing-related tau astrogliopathy (ARTAG), 45 (22%) with argyrophilic grain disease (AGD) and 2 cases (1%) with corticobasal degeneration (CBD). Patients with ARTAG or AGD were significantly older than those without these comorbidities. One of the patients with FTLD-TDP and CBD had C9orf72 mutation and relatively mild tau pathology, consistent with incidental CBD. CONCLUSION: The coexistence of TDP-43 and tau pathologies was relatively common, particularly PART and ARTAG. Although rare, patients with FTLD can have multiple neurodegenerative proteinopathies. The absence of TDP-43-positive astrocytic plaques may suggest that CBD and FTLD-TDP were independent disease processes in the two patients with both tau and TDP-43 pathologies. It remains to be determined if mixed cases represent a unique disease process or two concurrent disease processes in an individual.

Lewy Body Disease is a Contributor to Logopenic Progressive Aphasia Phenotype.

OBJECTIVE: The objective of this study was to describe clinical features, [18 F]-fluorodeoxyglucose (FDG)-positron emission tomography (PET) metabolism and digital pathology in patients with logopenic progressive aphasia (LPA) and pathologic diagnosis of diffuse Lewy body disease (DLBD) and compare to patients with LPA with other pathologies, as well as patients with classical features of probable dementia with Lewy bodies (pDLB). METHODS: This is a clinicopathologic case-control study of 45 patients, including 20 prospectively recruited patients with LPA among whom 6 were diagnosed with LPA-DLBD. We analyzed clinical features and compared FDG-PET metabolism in LPA-DLBD to an independent group of patients with clinical pDLB and regional α-synuclein burden on digital pathology to a second independent group of autopsied patients with DLBD pathology and antemortem pDLB (DLB-DLBD). RESULTS: All patients with LPA-DLBD were men. Neurological, speech, and neuropsychological characteristics were similar across LPA-DLBD, LPA-Alzheimer's disease (LPA-AD), and LPA-frontotemporal lobar degeneration (LPA-FTLD). Genetic screening of AD, DLBD, and FTLD linked genes were negative with the exception of APOE ε4 allele present in 83% of LPA-DLBD patients. Seventy-five percent of the patients with LPA-DLBD showed a parietal-dominant pattern of hy pometabolism; LPA-FTLD - temporal-dominant pattern, whereas LPA-AD showed heterogeneous patterns of hypometabolism. LPA-DLBD had more asymmetrical hypometabolism affecting frontal lobes, with relatively spared occipital lobe in the nondominantly affected hemisphere, compared to pDLB. LPA-DLBD had minimal atrophy on gross brain examination, higher cortical Lewy body counts, and higher α-synuclein burden in the middle frontal and inferior parietal cortices compared to DLB-DLBD. INTERPRETATION: Whereas AD is the most frequent underlying pathology of LPA, DLBD can also be present and may contribute to the LPA phenotype possibly due to α-synuclein-associated functional impairment of the dominant parietal lobe. ANN NEUROL 2021;89:520-533.

Loss of Tmem106b exacerbates FTLD pathologies and causes motor deficits in progranulin-deficient mice.

Progranulin (PGRN) and transmembrane protein 106B (TMEM106B) are important lysosomal proteins implicated in frontotemporal lobar degeneration (FTLD) and other neurodegenerative disorders. Loss-of-function mutations in progranulin (GRN) are a common cause of FTLD, while TMEM106B variants have been shown to act as disease modifiers in FTLD. Overexpression of TMEM106B leads to lysosomal dysfunction, while loss of Tmem106b ameliorates lysosomal and FTLD-related pathologies in young Grn-/- mice, suggesting that lowering TMEM106B might be an attractive strategy for therapeutic treatment of FTLD-GRN. Here, we generate and characterize older Tmem106b-/- Grn-/- double knockout mice, which unexpectedly show severe motor deficits and spinal cord motor neuron and myelin loss, leading to paralysis and premature death at 11-12 months. Compared to Grn-/- , Tmem106b-/- Grn-/- mice have exacerbated FTLD-related pathologies, including microgliosis, astrogliosis, ubiquitin, and phospho-Tdp43 inclusions, as well as worsening of lysosomal and autophagic deficits. Our findings confirm a functional interaction between Tmem106b and Pgrn and underscore the need to rethink whether modulating TMEM106B levels is a viable therapeutic strategy.

Long-read targeted sequencing uncovers clinicopathological associations for C9orf72-linked diseases.

To examine the length of a hexanucleotide expansion in C9orf72, which represents the most frequent genetic cause of frontotemporal lobar degeneration and motor neuron disease, we employed a targeted amplification-free long-read sequencing technology: No-Amp sequencing. In our cross-sectional study, we assessed cerebellar tissue from 28 well-characterized C9orf72 expansion carriers. We obtained 3507 on-target circular consensus sequencing reads, of which 814 bridged the C9orf72 repeat expansion (23%). Importantly, we observed a significant correlation between expansion sizes obtained using No-Amp sequencing and Southern blotting (P = 5.0 × 10-4). Interestingly, we also detected a significant survival advantage for individuals with smaller expansions (P = 0.004). Additionally, we uncovered that smaller expansions were significantly associated with higher levels of C9orf72 transcripts containing intron 1b (P = 0.003), poly(GP) proteins (P = 1.3 × 10- 5), and poly(GA) proteins (P = 0.005). Thorough examination of the composition of the expansion revealed that its GC content was extremely high (median: 100%) and that it was mainly composed of GGGGCC repeats (median: 96%), suggesting that expanded C9orf72 repeats are quite pure. Taken together, our findings demonstrate that No-Amp sequencing is a powerful tool that enables the discovery of relevant clinicopathological associations, highlighting the important role played by the cerebellar size of the expanded repeat in C9orf72-linked diseases.

Trends in Adoption and Maturation of Telehealth Programs at Teaching Hospitals and Health Systems.

Introduction: Although early adopters of telehealth have built and sustained telehealth programs over long periods, little research has been conducted differentiating the characteristics of health systems at different stages of maturation. Methods: This study surveyed 165 major teaching hospitals and health systems from fiscal year 2015 through 2018 about the stage and characteristics of their telehealth services. Respondents reported (i) the progression level of their telehealth program, (ii) which of six services they provide, and (iii) greatest barriers and motivators to implementing telehealth, as well as their overall operational and financial characteristics. Results: Telehealth programs at teaching hospitals progressed steadily and adoption of a wide range of telehealth delivery modes expanded. Hospital operational and financial characteristics corresponding to both higher maturation and the adoption of more delivery modes were identified. Reported barriers and motivations were similar across maturation levels. Discussion: With telehealth's broader use and the heterogeneity of delivery modes being utilized, a binary metric of whether or not to implement telehealth does not sufficiently capture key differences in telehealth programs or differentiate implementation scope and scale across health systems. Conclusions: The findings suggest that programs at different levels of maturation are characteristically different from one another. Identifying factors related to mature telehealth programs may help guide policymakers, future telehealth program leaders, and other stakeholders in identifying barriers to continued investment in telehealth.

Old age genetically confirmed frontotemporal lobar degeneration with TDP-43 has limbic predominant TDP-43 deposition.

AIMS: To assess the burden of transactive response DNA-binding protein of 43 kDa (TDP-43) inclusions in a unique cohort of old-age patients with genetic frontotemporal lobar degeneration (gFTLD-TDP) and compare these patients with sporadic old-age individuals with TDP-43, either in the presence of Alzheimer's disease (AD-TDP) or in isolation (pure-TDP). METHODS: The brain bank at Mayo Clinic-Jacksonville was searched for cases ≥75 years old at death with TDP-43 extending into middle frontal cortex. Cases were split into the following groups: (1) gFTLD-TDP (n = 15) with progranulin (GRN)/C9ORF72 mutations; (2) AD-TDP (n = 10)-cases with median Braak neurofibrillary tangle (NFT) stage VI, Thal phase V; (3) pure-TDP (n = 10)-cases with median Braak NFT stage I, Thal phase I. Clinical data were abstracted; TDP-43 burden was calculated using digital pathology. RESULTS: Amnestic Alzheimer's dementia was the clinical diagnosis in ≥50% patients in each group. The distribution of TDP-43 burden in gFTLD-TDP and AD-TDP, but not pure-TDP, was limbic-predominant targeting CA1 and subiculum. Patients with gFTLD-TDP had higher burden in entorhinal cortex compared to AD-TDP. TDP-43 burden in middle frontal cortex did not differ between the three groups. CONCLUSIONS: In old age it is challenging to clinically and pathologically differentiate gFTLD-TDP from AD-TDP and pure-TDP-43 based on burden. Like AD-TDP, old age gFTLD-TDP have a limbic predominant TDP-43 distribution. The finding that amnestic Alzheimer's dementia was the most common clinical diagnosis regardless of group suggests that TDP-43 directly and indirectly targets limbic regions.

Latent trait modeling of tau neuropathology in progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is the second most common neurodegenerative Parkinsonian disorder after Parkinson's disease, and is characterized as a primary tauopathy. Leveraging the considerable clinical and neuropathologic heterogeneity associated with PSP, we measured tau neuropathology as quantitative traits to perform a genome-wide association study (GWAS) within PSP to identify genes and biological pathways that underlie the PSP disease process. In 882 PSP cases, semi-quantitative scores for phosphorylated tau-immunoreactive coiled bodies (CBs), neurofibrillary tangles (NFTs), tufted astrocytes (TAs), and tau threads were documented from 18 brain regions, and converted to latent trait (LT) variables using the R ltm package. LT analysis utilizes a multivariate regression model that links categorical responses to unobserved covariates allowing for a reduction of dimensionality, generating a single, continuous variable to account for the multiple lesions and brain regions assessed. We first tested for association with PSP LTs and the top PSP GWAS susceptibility loci. Significant SNP/LT associations were identified at rs242557 (MAPT H1c sub-haplotype) with hindbrain CBs and rs1768208 (MOBP) with forebrain tau threads. Digital microscopy was employed to quantify phosphorylated tau burden in midbrain tectum and red nucleus in 795 PSP cases and tau burdens were used as quantitative phenotypes in GWAS. Top associations were identified at rs1768208 with midbrain tectum and red nucleus tau burden. Additionally, we performed a PSP LT GWAS on an initial cohort, a follow-up SNP panel (37 SNPs, P < 10-5) in an extended cohort, and a combined analysis. Top SNP/LT associations were identified at SNPs in or near SPTBN5/EHD4, SEC13/ATP2B2, EPHB1/PPP2R3A, TBC1D8, IFNGR1/OLIG3, ST6GAL1, HK1, CALB1, and SGCZ. Finally, testing for SNP/transcript associations using whole transcriptome and whole genome data identified significant expression quantitative trait loci at rs3088159/SPTBN5/EHD4 and rs154239/GHRL. Modeling tau neuropathology heterogeneity using LTs as quantitative phenotypes in a GWAS may provide substantial insight into biological pathways involved in PSP by affecting regional tau burden.

Neurobehavioral Characteristics of FDG-PET Defined Right-Dominant Semantic Dementia: A Longitudinal Study.

INTRODUCTION: Semantic dementia (SD) is characterized by fluent speech, anomia, and loss of word and object knowledge with varying degrees of right and left anterior-medial temporal lobe hypometabolism on [18F] fluorodeoxyglucose (FDG)-PET. We assessed neurobehavioral features in SD patients across 3 FDG-PET-defined metabolic patterns and investigated progression over time. METHODS: Thirty-four patients with SD who completed FDG-PET were classified into a left- and right-dominant group based on the degree of hypometabolism in each temporal lobe. The left-dominant group was further subdivided depending on whether hypometabolism in the right temporal lobe was more or less than 2 standard deviations from controls (left+ group). Neurobehavioral characteristics determined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) were compared across groups. Progression of NPI-Q scores and FDG-PET hypometabolism was assessed in 14 patients with longitudinal follow-up. RESULTS: The right-dominant group performed worse on the NPI-Q and had a greater frequency of abnormal behaviors and more severe disinhibition compared to the left-dominant group. Performance on the NPI-Q and severity of disinhibition correlated with right medial and lateral, but not left, temporal lobe hypometabolism. Severity of abnormal behaviors worsened over time in most left-dominant and left+ patients but appeared to improve in the 2 right-dominant patients with longitudinal follow-up. All groups showed progressive worsening of metabolism in both temporal lobes over time, with hypometabolism spreading from anteromedial to posterior temporal regions. However, the degree of temporal lobe asymmetry remained relatively constant over time. CONCLUSION: In SD, neurobehavioral features, especially disinhibition, are associated with right medial and lateral temporal lobe hypometabolism and commonly develop over time even in patients that present with left-dominant patterns of hypometabolism.

Repetitive element transcripts are elevated in the brain of C9orf72 ALS/FTLD patients.

Significant transcriptome alterations are detected in the brain of patients with amyotrophic lateral sclerosis (ALS), including carriers of the C9orf72 repeat expansion and C9orf72-negative sporadic cases. Recently, the expression of repetitive element transcripts has been associated with toxicity and, while increased repetitive element expression has been observed in several neurodegenerative diseases, little is known about their contribution to ALS. To assess whether aberrant expression of repetitive element sequences are observed in ALS, we analysed RNA sequencing data from C9orf72-positive and sporadic ALS cases, as well as healthy controls. Transcripts from multiple classes and subclasses of repetitive elements (LINEs, endogenous retroviruses, DNA transposons, simple repeats, etc.) were significantly increased in the frontal cortex of C9orf72 ALS patients. A large collection of patient samples, representing both C9orf72 positive and negative ALS, ALS/FTLD, and FTLD cases, was used to validate the levels of several repetitive element transcripts. These analyses confirmed that repetitive element expression was significantly increased in C9orf72-positive compared to C9orf72-negative or control cases. While previous studies suggest an important link between TDP-43 and repetitive element biology, our data indicate that TDP-43 pathology alone is insufficient to account for the observed changes in repetitive elements in ALS/FTLD. Instead, we found that repetitive element expression positively correlated with RNA polymerase II activity in postmortem brain, and pharmacologic modulation of RNA polymerase II activity altered repetitive element expression in vitro. We conclude that increased RNA polymerase II activity in ALS/FTLD may lead to increased repetitive element transcript expression, a novel pathological feature of ALS/FTLD.