Quantification of myelin loss in frontal lobe white matter in vascular dementia, Alzheimer's disease, and dementia with Lewy bodies

The aim of this study was to characterize myelin loss as one of the features of white matter abnormalities across three common dementing disorders. We evaluated post-mortem brain tissue from frontal and temporal lobes from 20 vascular dementia (VaD), 19 Alzheimer’s disease (AD) and 31 dementia with Lewy bodies (DLB) cases and 12 comparable age controls. Images of sections stained with conventional luxol fast blue were analysed to estimate myelin attenuation by optical density. Serial adjacent sections were then immunostained for degraded myelin basic protein (dMBP) and the mean percentage area containing dMBP (%dMBP) was determined as an indicator of myelin degeneration. We further assessed the relationship between dMBP and glutathione S-transferase (a marker of mature oligodendrocytes) immunoreactivities. Pathological diagnosis significantly affected the frontal but not temporal lobe myelin attenuation: myelin density was most reduced in VaD compared to AD and DLB, which still significantly exhibited lower myelin density compared to ageing controls. Consistent with this, the degree of myelin loss was correlated with greater %dMBP, with the highest %dMBP in VaD compared to the other groups. The %dMBP was inversely correlated with the mean size of oligodendrocytes in VaD, whereas it was positively correlated with their density in AD. A two-tier regression model analysis confirmed that the type of disorder (VaD or AD) determines the relationship between %dMBP and the size or density of oligodendrocytes across the cases. Our findings, attested by the use of three markers, suggest that myelin loss may evolve in parallel with shrunken oligodendrocytes in VaD but their increased density in AD, highlighting partially different mechanisms are associated with myelin degeneration, which could originate from hypoxic–ischaemic damage to oligodendrocytes in VaD whereas secondary to axonal degeneration in AD

LATE-NC staging in routine neuropathologic diagnosis : an update

An international consensus report in 2019 recommended a classification system for limbic-predominant age-related TDP-43 encephalopathy neuropathologic changes (LATE-NC). The suggested neuropathologic staging system and nomenclature have proven useful for autopsy practice and dementia research. However, some issues remain unresolved, such as cases with unusual features that do not fit with current diagnostic categories. The goal of this report is to update the neuropathologic criteria for the diagnosis and staging of LATE-NC, based primarily on published data. We provide practical suggestions about how to integrate available genetic information and comorbid pathologies [e.g., Alzheimer's disease neuropathologic changes (ADNC) and Lewy body disease]. We also describe recent research findings that have enabled more precise guidance on how to differentiate LATE-NC from other subtypes of TDP-43 pathology [e.g., frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS)], and how to render diagnoses in unusual situations in which TDP-43 pathology does not follow the staging scheme proposed in 2019. Specific recommendations are also made on when not to apply this diagnostic term based on current knowledge. Neuroanatomical regions of interest in LATE-NC are described in detail and the implications for TDP-43 immunohistochemical results are specified more precisely. We also highlight questions that remain unresolved and areas needing additional study. In summary, the current work lays out a number of recommendations to improve the precision of LATE-NC staging based on published reports and diagnostic experience.Peer reviewe

SFN action impacts HIV-2 as well as HIV-1 and is not reporter dependent.

<p>PMA-differentiated THP1 cells were treated with media supplemented with vehicle only (DMSO), 5 μM AZT or with 10 μM SFN. Twenty-four hours after treatment, the samples were either mock infected or infected with (A), VSV-G pseudotyped HIV-1 encoding firefly luciferase in place of <i>nef</i> or (B), VSV-G pseudotyped HIV-2 encoding firefly luciferase in place of <i>nef</i>. Twenty-four hours after infection, luciferase activity was measured by photon emission. (C), In parallel, the same experiment as in (A) and (B) was performed except that THP1 cells were infected with VSV-G-pseudotyped HIV-1 with GFP in place of <i>nef</i> or (D), VSV-G pseudotyped HIV-2 with GFP in place of <i>nef</i>. The samples with GFP-reporter viruses were fixed and harvested 24 h after infection and the fraction of GFP(+) cells was enumerated by flow cytometry. Bar graphs represent the data for replicate experiments (n = 3).</p

SFN action blocks spreading infections that rely on the HIV envelope for viral entry.

<p>hMDMs were pretreated with vehicle (DMSO), 5 μM AZT, or 10 μM SFN. All cultures were subsequently maintained in their respective treatments for the duration of the experiment. Twenty four hours after initial treatment, the cultures were infected with the HIV-1 clinical isolate 89.6. Culture supernatants were collected 3, 6, 9, and 14 days after infection. (A), Western blots and (B), p24 antigen ELISA assays of viral supernatants were performed. (C), Fourteen days after infection, cells were imaged using phase contrast microscopy. (D), Uninfected replicate cultures were maintained in the presence of vehicle (DMSO) or in 10 μM SFN. After 14 days of treatment, the viability of each cell type was assessed under each condition by measuring water-soluble tetrazolium salt (WST-8) formazan reagent cleavage by cellular dehydrogenases. Continuous treatment of cells with 10 μg/ml of the eukaryotic toxin blasticidin served as a positive control to demonstrate loss of viability. (E), hMDMs were infected with 89.6-Env-pseudotyped HIV-1 encoding firefly luciferase in place of <i>nef</i>. The bar graphs represent the data for replicate experiments (n = 3).</p

The SFN-mediated HIV infection block is reversible.

<p>(A), Study design: PMA-differentiated THP1 cells were pretreated with media supplemented with vehicle only (DMSO) or with 10 μM, 20 μM or 30 μM SFN. After twenty-four hours of treatment, the culture media was replaced with fresh SFN-free media. Cultures were infected 1, 2, 3, 4, or 5 days after treatment with freshly thawed aliquots of VSV-G pseudotyped HIV-1 encoding firefly luciferase in place of <i>nef</i>. Twenty-four hours after the start of each time-point infection, the cells were harvested and (B), luciferase activity was measured by photon emission. The bar graph represents the data for replicate experiments (n = 3).</p

SFN blocks infection after entry and but before 2-LTR circle formation.

<p>Replicate cultures of hMDMs were pretreated with vehicle (DMSO)-containing media, with 5 μM AZT or with 10 μM SFN. Twenty four hours after treatment, the samples were infected with VSV-G-pseudotyped HIV-1 encoding GFP in place of <i>nef</i>. Cultures treated with heat-inactivated virus served as controls for plasmid carry over and for impaired viral entry. Cells were harvested and DNA was isolated 24 hours after infection. Viral DNA products were detected by real-time PCR using primer sets specific for the indicated stage of reverse transcription. (A), Relative quantities of late reverse transcription products, (B), 2-LTR circles, and (C), integrated proviruses. The bar graph represents the data for replicate experiments (n = 3).</p

SFN blocks HIV infection in monocytoid cell lines but does not increase SAMHD1 expression.

<p>(A), HeLa, (B), GHOST, (C), HEK293T, (D), PMA-differentiated U937, and (E), PMA-differentiated THP1, cells were treated with media supplemented with vehicle only (DMSO) or with 10 μM, 20 μM or 30 μM SFN. Pretreatment of cell cultures with 5 μM AZT served as a positive control for viral inhibition. Twenty-four hours after treatment, the samples were infected with VSV-G pseudotyped HIV-1 encoding firefly luciferase in place of <i>nef</i>. Twenty-four hours after infection, the cultures were harvested and luciferase activity was measured by photon emission. (F), PMA-differentiated THP1 cells were treated with SFN that underwent a twofold serial dilution with 10μM of SFN being the highest concentration. Twenty-four hours after treatment, the samples were either mock infected or infected with VSV-G pseudotyped HIV-1 encoding firefly luciferase in place of <i>nef</i>. Twenty-four hours after infection, luciferase activity was measured. The bar graphs represent the data for replicate experiments (n = 3). (G), SAMHD1 protein was detected by western blot analysis from lysates of mock- and SFN treated PMA-differentiated U937 cells. Lysates from mock-treated, PMA-differentiated THP1 cells served as a positive control for SAMHD1 production.</p

SFN does not trigger expression of interferon-stimulated anti-viral factors SAMHD1 or MX2.

<p>PMA-differentiated THP1 cells were mock-treated or treated with media supplemented with vehicle only (DMSO) or with 10 μM SFN or with 500 U/mL of IFNα. (A), Proteins from whole cell lysates were resolved by SDS-PAGE and identified by western blotting using antibodies with the indicated specificities. (B), Densitometric analysis was performed on the Nrf2, SAMHD1, MX2, NQO1 and GCLM (NQO1 and GCLM are both indicators of Nrf2 function) bands and normalized to the values of the corresponding tubulin bands. The relative normalized intensities of the bands were then graphed.</p

The major genetic determinants of HIV-1 control affect HLA class I peptide presentation.

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified &gt;300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection