Performance evaluation of automated white matter hyperintensity segmentation algorithms in a multicenter cohort on cognitive impairment and dementia

Background: White matter hyperintensities (WMH), a biomarker of small vessel disease, are often found in Alzheimer’s disease (AD) and their advanced detection and quantification can be beneficial for research and clinical applications. To investigate WMH in large-scale multicenter studies on cognitive impairment and AD, appropriate automated WMH segmentation algorithms are required. This study aimed to compare the performance of segmentation tools and provide information on their application in multicenter research. Methods: We used a pseudo-randomly selected dataset (n = 50) from the DZNE-multicenter observational Longitudinal Cognitive Impairment and Dementia Study (DELCODE) that included 3D fluid-attenuated inversion recovery (FLAIR) images from participants across the cognitive continuum. Performances of top-rated algorithms for automated WMH segmentation [Brain Intensity Abnormality Classification Algorithm (BIANCA), lesion segmentation toolbox (LST), lesion growth algorithm (LGA), LST lesion prediction algorithm (LPA), pgs, and sysu_media] were compared to manual reference segmentation (RS). Results: Across tools, segmentation performance was moderate for global WMH volume and number of detected lesions. After retraining on a DELCODE subset, the deep learning algorithm sysu_media showed the highest performances with an average Dice’s coefficient of 0.702 (±0.109 SD) for volume and a mean F1-score of 0.642 (±0.109 SD) for the number of lesions. The intra-class correlation was excellent for all algorithms (>0.9) but BIANCA (0.835). Performance improved with high WMH burden and varied across brain regions. Conclusion: To conclude, the deep learning algorithm, when retrained, performed well in the multicenter context. Nevertheless, the performance was close to traditional methods. We provide methodological recommendations for future studies using automated WMH segmentation to quantify and assess WMH along the continuum of cognitive impairment and AD dementia

Antigen delivery to dendritic cells shapes human CD4⁺ and CD8⁺ T cell memory responses to <i>Staphylococcus aureus</i>

<div><p>Intracellular persistence of <i>Staphylococcus aureus</i> favors bacterial spread and chronic infections. Here, we provide evidence for the existence of human CD4⁺ and CD8⁺ T cell memory against staphylococcal antigens. Notably, the latter could provide a missing link in our understanding of immune control of intracellular <i>S</i>. <i>aureus</i>. The analyses showed that pulsing of monocyte-derived dendritic cells (MoDC) with native staphylococcal protein antigens induced release of Th2-associated cytokines and mediators linked to T regulatory cell development (G-CSF, IL-2 and IL-10) from both CD4⁺ and CD8⁺ T cells, thus revealing a state of tolerance predominantly arising from preformed memory T cells. Furthermore, G-CSF was identified as a suppressor of CD8⁺ T cell-derived IFNγ secretion, thus confirming a tolerogenic role of this cytokine in the regulation of T cell responses to <i>S</i>. <i>aureus</i>. Nevertheless, delivery of <i>in vitro</i> transcribed mRNA-encoded staphylococcal antigens triggered Th1-biased responses, e.g. IFNγ and TNF release from both naïve and memory T cells. Collectively, our data highlight the potential of mRNA-adjuvanted antigen presentation to enable inflammatory responses, thus overriding the existing Th2/Treg-biased memory T cell response to native <i>S</i>. <i>aureus</i> antigens.</p></div

Turn Plasticity Distinguishes Different Modes of Amyloid‑β Aggregation

Pathogenesis of Alzheimer’s disease (AD) is associated with aggregation of the amyloid-β (Aβ) peptide into oligomeric and fibrillar assemblies; however, little is known about the molecular basis of aggregation of Aβ into distinct assembly states. Here we demonstrate that phosphorylation at serine 26 (S26) impairs Aβ fibrillization while stabilizing its monomers and nontoxic soluble assemblies of nonfibrillar morphology. NMR spectroscopy and replica-exchange molecular dynamics indicate that introduction of a phosphate group or phospho­mimetic at position 26 diminishes Aβ’s propensity to form a β-hairpin, rigidifies the region around the modification site, and interferes with formation of a fibril-specific salt bridge between aspartic acid 23 and lysine 28. The combined data demonstrate that phosphorylation of S26 prevents a distinct conformational rearrangement that is required for progression of Aβ aggregation toward fibrils and provide a basis for a possible role of phosphorylation at serine 26 in AD

T cell cytokine profiles in response to <i>spa</i> mRNA-encoded and SpA protein delivered antigens.

<p>Cytokine secretion profiles in day 5 supernatants of CD4⁺ (left panel) or CD8⁺ T cells (right panel) stimulated with <i>spa</i> mRNA or SpA protein antigens was performed using a multiplex cytokine array: <b>(a)</b> Th1 cytokines (IFNγ, TNF) and <b>(b)</b> Th2 cytokines (IL-5, IL-13). The graphs depict the mean values ± SEM obtained from n = 6 independent donors. Experiments were carried out in duplicates. For Th1 cytokines, one-way ANOVA was used to test significance of multiple conditions; for Th2 cytokines, p values refer to condition with <i>spa</i> mRNA (paired student’s t-test; p**<0.01, p*< 0.05).</p

Protein-derived antigens activate memory T cells.

<p>Human <b>(a)</b> CD4⁺ or <b>(b)</b> CD8⁺ T cells were isolated from frozen PBMC via magnetic beads. Cell fractions were either purified for <b>(a)</b> CD14^-CD8^- and <b>(b)</b> CD14^-CD8⁺, and CD45RO^-CD45RA⁺ (naïve) or CD45RO⁺CD45RA^- (memory) phenotype. Cytokine secretion profiles after 5 days of MoDC/T cell co-culture stimulated with SpA protein were measured by multiplex cytokine array, done in duplicates. TNF, IFNγ, IL-5 and IL-13 are presented as mean ± SEM of n = 7 or 8 donors, respectively. p value refers to the same condition in naïve T cells. p**<0.01, p*< 0.05 (paired student’s t-test). For testing of multiple conditions, one-way ANOVA was used.</p

Antigen source-dependent activation of different T cell subsets.

<p>MoDC/T cell co-cultures of n = 8 independent donors were stimulated with <i>spa</i>-encoding mRNA and/or SpA protein and analyzed by IFNγ/IL-13 FluoroSpot demonstrating cytokine secretion by different cell subsets dependent on the antigen delivery. The number of spots is displayed as mean values ± SEM. p*< 0.05, n.s. not significant (Wilcoxon matched-pairs signed rank test). Experiments were done in technical duplicates.</p

Comparison of IFNγ production by T cells stimulated with mRNA- or protein-derived staphylococcal antigens.

<p><b>(a)</b> CD4⁺ T cells and <b>(b)</b> CD8⁺ T cells in co-culture with MoDC were stimulated with either mRNA-encoded antigens or the corresponding protein antigens, e.g. <i>spa</i> / SpA, <i>mecA</i> / PBP2a and <i>sitC</i> / SitC. Lipofectamine (LF) alone, non-coding mRNA (NC) and a peptide pool from matrix protein 1 (MP1) of H1N1 Influenza virus and Tetanus toxoid (TT) served as controls. The number of IFNγ ELISpot spots after overnight culture is shown as mean values ± SEM of n = 8 donors. p**<0.01, p*< 0.05 (Wilcoxon matched-pairs signed rank test). Experiments were done in duplicates.</p

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G-CSF-mediated regulation of IFNγ production.

<p>Cytokine secretion profiles of <b>(a)</b> G-CSF, IL-2 and IL-10 in day 5 supernatants of CD4⁺ (left panel) or CD8⁺ T cells (right panel): MoDC/T cell co-cultures stimulated with <i>spa</i>, <i>mecA or sitC</i> mRNA or the corresponding protein antigens (SpA, PBP2a, SitC) were performed using a multiplex cytokine array. The graphs depict the mean values ± SEM obtained by n = 6 independent donors. Paired t-test was used to test for significance. The p-value refers to the mRNA condition of the corresponding protein antigen and cytokine. <b>(b+c)</b> MoDC were transfected with non-coding (NC) or <i>spa</i> mRNA and cultured in the presence of recombinant IL-2, IL-10 or G-CSF with <b>(b)</b> CD4⁺ or <b>(c)</b> CD8⁺ T cells. IFNγ ELISPOT enzymatic activity of n = 8 different donors was normalized to the NC mRNA control. Wilcoxon matched-pairs signed rank test was used to test for significance. If not indicated otherwise, p values refer to the untreated control transfected with <i>spa</i> mRNA. p**<0.01, p*< 0.05. All experiments were done in duplicates.</p

Additional file 5: Figure S5. of The release and trans-synaptic transmission of Tau via exosomes

Uptake and transmission of TauCFP by neurons cultured in microfluidic chambers via exosomes derived from cultured neurons. (A) Nanoparticle tracking analysis of exosomes derived from primary neurons transfected with TauCFP. The size distribution peaks at ~90 nm, indicating the enrichment of exosomes in the preparations. (B) Uptake and transmission of exosomes containing TauCFP isolated as in (A) by neurons cultured in microfluidic chambers with long microgrooves (900 nm). The 1st order neurons at DIV25 were treated for 24 h with exosomes (20 μg) isolated from primary cortical neurons infected with adeno-virus expressing TauCFP, when the 2nd order neurons were at DIV11. Neurons were then fixed and stained for immunofluorescence microscopy with antibodies against MAP2 (red). Arrows denote TauCFP exosomes. Scale bar = 10 μm. Note that TauCFP exosomes were detected in the 2nd order neurons on the neuritic side, indicating their uptake by 1st order neurons on the somal side, transport across the microgrooves, and synaptic transmission to the neurons on the neuritic side. (PNG 157 kb