Roemer, Shanu F.

AbstractBackgroundPerturbations in immune pathways are strongly associated with Alzheimer’s disease. A positive association between autoimmune diseases and frontotemporal dementia has been reported. We explored whether early onset Alzheimer’s disease (EOAD) would associate with autoimmune diseases.MethodWe compared 313 patients with EOAD from the Mayo Clinic Florida, Alzheimer’s Disease Research Center (ADRC) Registry with matched cognitively normal controls (NC) based on age (+/‐ 2 years) and gender at 1:2 ratio. NC were derived from Mayo Clinic Biobank Project, Rochester (N = 313) and the Mayo Clinic Study of Aging (N = 313). Data abstraction was performed by trained statisticians using ICD 9&10 codes corresponding to 40 specified autoimmune diseases and/or documentation of specified immunomodulatory treatment. Data was also abstracted via retrospective record review. We further reviewed clinical records from EOAD patients with neuropathologically confirmed Alzheimer’s disease patients enrolled in the ADRC (n = 10). Each autoimmune disease type was compared between cases and controls using Fisher’s exact test. All tests were two‐sided with alpha level set at 0.05 for statistical significance. Continuous variables were summarized as median (range) while categorical variables were reported as frequency (percentage). The prevalence of autoimmune disease in the general population was based off Hayter & Cook, 2012 and Roberts & Erdei, 2020. All data abstraction was done blinded to the clinical diagnosis and baseline demographics.ResultAutoimmune disease history was abstracted from 949 patient records (313 EOAD, 10 pathologically‐confirmed EOAD, 626 NCI). The median age was 57 years‐old. (EOAD range 28,65 yrs.; NC 30,66 yrs.). Autoimmune thyroiditis (p = 0.0008), ulcerative colitis (p = 0.011, psoriasis (<0.0001), rheumatoid arthritis (p = 0.0005), and Raynaud’s syndrome (p = 0.0021) were less prevalent in patients with EOAD compared to NC. Furthermore, patients with EOAD had a lower prevalence of immune mediated hematologic disorders.ConclusionPatients with EOAD have a lower prevalence of autoimmune diseases than NC. Immune activation identified in early onset AD patients may be unrelated to autoimmunity. Findings should be explored in late onset AD patients.

Amyotrophic lateral sclerosis (ALS) is a fatal disease affecting upper and lower motor neurons. Microglia directly interact with motor neurons and participate in the progression of ALS. Single-cell mass cytometry (CyTOF) analysis revealed prominent expression of α5 integrin in microglia and macrophages in a superoxide dismutase-1 G93A mouse model of ALS (SOD1 G93A ). In postmortem tissues from ALS patients with various clinical ALS phenotypes and disease duration, α5 integrin is prominent in motor pathways of the central and peripheral nervous system and in perivascular zones associated with the blood–brain barrier. In SOD1 G93A mice, administration of a monoclonal antibody against α5 integrin increased survival compared to an isotype control and improved motor function on behavioral testing. Together, these findings in mice and in humans suggest that α5 integrin is a potential therapeutic target in ALS.

AbstractBackgroundMost series exploring the causes of rapidly progressive dementia (RPD) rely on clinical diagnoses, with limited pathological confirmation. This approach may underestimate the contributions of Alzheimer disease and related dementias to RPD, recognizing challenges associated with extrapolating clinical phenotypes to neuropathological diagnoses. A clearer understanding of the neuropathological causes of RPD is needed to inform the diagnosis and treatment of patients. To meet this need, we determined the neuropathological causes of RPD within the Mayo Clinic neurodegenerative brain bank.MethodPatients with disease duration <4.0 years (symptom‐onset to death due to dementia) were identified within the Mayo Clinic neurodegenerative brain bank (1998‐2020). Available clinical records were reviewed, and details extracted including demographics, family history, dominant symptoms/signs at onset, and common comorbidities (depression, psychoses, sleep disturbance). Neuropathological diagnoses were assigned following standard protocols.Result310/8586 (3.6%) cases met RPD criteria. Relative to typically progressive cases, prion disease most commonly presented as RPD (74%, 32/43), followed by progressive supranuclear palsy/corticobasal degeneration (PSP/CBD: 7.5%, 142/1894), other frontotemporal lobar degeneration (FTLD: 5.7%, 32/561), Lewy body disease (LBD: 4.1%, 49/1202), and Alzheimer disease (AD: 1.8%, 48/2687). Average age‐at‐symptom onset was 69.5±10.4 years. Patients with rapidly progressive AD were older than others (p<0.01), except LBD. Patients with FTLD were younger than others (p<0.05), except prion disease. Average disease duration was 2.9±1.0 years: prion diseases had the most rapid disease course (1.6±1.3 years). Comorbid cerebrovascular disease (25.5%), and clinically symptomatic depression (41.3%), psychoses (37.1%) and sleep disturbances (39.4%) were common across groups. Only psychosis was associated with shorter disease duration (β=‐0.31 years, CI95% [‐0.53, ‐0.082]; controlling for age‐at‐symptom onset).ConclusionRapidly progressive neurodegenerative diseases accounted for 3.6% of cases in this neurodegenerative brain bank. Although prion disease commonly presented as RPD, atypical presentations of more prevalent neurodegenerative diseases accounted for most cases. Atypical (rapidly progressive) variants of typical neurodegenerative diseases warrant consideration in clinical practice.

AbstractBackground: Abnormal aggregates of α‐synuclein are pathologic hallmarks of multiple system atrophy (MSA) and Lewy body disease (LBD). LBD sometimes coexists with MSA, but the impact of co‐pathology, particularly diffuse LBD, on presentation of MSA has not been studied. We aimed to determine the frequency and clinicopathologic features of MSA with LBD (MSA+LBD). Methods: Using hematoxylin & eosin and α‐synuclein‐immunostained slides, we assessed the distribution and severity of LBD in 230 autopsy‐confirmed MSA patients collected from 1998 to 2018. Alzheimer‐type pathology was assessed to assign the likelihood of clinical presentations of dementia with Lewy body (DLB) using the consensus criteria for DLB. We reviewed medical records to characterize clinicopathologic features of MSA+LBD. Genetic risk factors for LBD, including APOE ε4 allele and mutations in GBA, SNCA, LRRK2, and VPS35, were analyzed. Results: LBD was observed in 11 MSA patients (5%); seven were brainstem type, three were transitional type, and one was diffuse type. The latter four had an intermediate or high likelihood of DLB. Three of the four had an antemortem diagnosis of Parkinson’s disease with dementia (PDD) or clinically probable DLB. Two patients had neuronal loss in the substantia nigra, but not in striatal or olivocerebellar systems with widespread glial cytoplasmic inclusions, consistent with minimal change MSA. In these cases, LBD was considered the primary pathology, and MSA was considered coincidental. APOE ε4 allele frequency was not different between MSA+LBD and MSA without LBD. Two of nine MSA+LBD patients had a risk variant of GBA (p.T408M and p.E365K). Conclusions: Although rare, MSA with transitional or diffuse LBD can develop clinical features of PDD or DLB. Minimal change MSA can be interpreted as a coincidental, but distinct, α‐synucleinopathy in a subset of patients with diffuse LBD.

AbstractObjectiveTo identify clinicopathological differences between frontotemporal lobar degeneration (FTLD) due to mutations in progranulin (FTLD‐GRN) and chromosome 9 open reading frame 72 (FTLD‐C9ORF72).MethodsWe performed quantitative neuropathologic comparison of 17 FTLD‐C9ORF72 and 15 FTLD‐GRN with a focus on microglia. For clinical comparisons, only cases with high quality medical documentation and concurring diagnoses by at least two neurologists were included (14 FTLD‐GRN and 13 FTLD‐C9ORF72). Neuropathological analyses were limited to TDP‐43 Type A to assure consistent assessment between the groups, acknowledging that Type A is a minority of C9ORF72 patients. Furthermore, only cases with sufficient tissue from all regions were studied (11 FTLD‐GRN and 11 FTLD‐C9ORF72). FTLD cases were also compared to age– and sex–matched normal controls. Immunohistochemistry was performed for pTDP‐43, IBA‐1, CD68, and GFAP. Morphological characterization of microglia was performed in sections of cortex blinded to clinical and genetic information.ResultsFTLD‐GRN patients had frequent asymmetric clinical features, including aphasia and apraxia, as well as more asymmetric cortical atrophy. Neuropathologically, FTLD‐C9ORF72 had greater hippocampal tau pathology and more TDP‐43 neuronal cytoplasmic inclusions. FTLD‐GRN had more neocortical microvacuolation, as well as more IBA‐1–positive ameboid microglia in superficial cortical layers and in subcortical white matter. FTLD‐GRN also had more microglia with nuclear condensation, possibly indicating apoptosis. Microglial morphology with CD68 immunohistochemistry in FTLD‐GRN and FTLD‐C9ORF72 differed from controls.InterpretationOur findings underscore differences in microglial response in FTLD‐C9ORF72 and FTLD‐GRN as shown by significant differences in ameboid microglia in gray and white matter. These results suggest the differential contribution of microglial dysfunction in FTLD‐GRN and FTLD‐C9ORF72 and suggest that clinical, neuroimaging and pathologic differences could in part be related to differences in microglia response.

AbstractProgressive supranuclear palsy with predominant cerebellar ataxia (PSP-C) has been reported as a rare clinical subtype, but the underlying pathology of its cerebellar ataxia remains unclear. Here, we report a patient with the coexistence of PSP with pontocerebellar atrophy and myotonic dystrophy type 1 (DM1). A 73-year-old man who was an asymptomatic carrier of DM1 (66 CTG repeats) started developing ataxic gait with multiple falls, visual blurring, double vision, and word finding difficulty at age 62 and was initially diagnosed with multiple system atrophy (MSA). Subsequently, the diagnosis was changed to PSP due to hypometric downward gaze, reduced blink frequency, symmetric bradykinesia, rigidity, and the absence of autonomic dysfunction. He eventually developed delayed grip opening with percussion myotonia at age 72. At autopsy, severe neuronal degeneration and astrogliosis in the pontocerebellar structures suggested MSA, but immunohistochemistry for α-synuclein did not reveal neuronal or glial cytoplasmic inclusions. Immunohistochemistry for phospho-tau and 4-repeat tau confirmed a neuropathological diagnosis of PSP with exceptionally numerous coiled bodies and threads in the pontine base and cerebellar white matter. This unusual distribution of 4-repeat tau pathology and neuronal degeneration with astrogliosis is a plausible clinicopathological substrate of PSP-C.

Neuromyelitis optica (NMO)-immunoglobulin G (IgG) is a clinically validated serum biomarker that distinguishes relapsing central nervous system (CNS) inflammatory demyelinating disorders related to NMO from multiple sclerosis. This autoantibody targets astrocytic aquaporin-4 (AQP4) water channels. Clinical, radiological, and immunopathological data suggest that NMO-IgG might be pathogenic. Characteristic CNS lesions exhibit selective depletion of AQP4, with and without associated myelin loss; focal vasculocentric deposits of IgG, IgM, and complement; prominent edema; and inflammation. The effect of NMO-IgG on astrocytes has not been studied. In this study, we demonstrate that exposure to NMO patient serum and active complement compromises the membrane integrity of CNS-derived astrocytes. Without complement, astrocytic membranes remain intact, but AQP4 is endocytosed with concomitant loss of Na+-dependent glutamate transport and loss of the excitatory amino acid transporter 2 (EAAT2) . Our data suggest that EAAT2 and AQP4 exist in astrocytic membranes as a macromolecular complex. Transport-competent EAAT2 protein is up-regulated in differentiating astrocyte progenitors and in nonneural cells expressing AQP4 transgenically. Marked reduction of EAAT2 in AQP4-deficient regions of NMO patient spinal cord lesions supports our immunocytochemical and immunoprecipitation data. Thus, binding of NMO-IgG to astrocytic AQP4 initiates several potentially neuropathogenic mechanisms: complement activation, AQP4 and EAAT2 down-regulation, and disruption of glutamate homeostasis.