Biology subjects

Iwahara, N.

Publications and source records attributed to Iwahara, N..

3 recordsLinked to original sources

bioRxiv2023

Neutralizing antibody responses and cellular responses against severe acute respiratory syndrome coronavirus 2 omicron subvariant BA.5 after an mRNA severe acute respiratory syndrome coronavirus 2 vaccine dose in kidney transplant recipients

We examined the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein IgG antibody and neutralizing antibody titers and cellular immunity in 73 uninfected recipients and 17 uninfected healthy controls who received three doses of a coronavirus 2019 mRNA vaccine. Neutralizing antibody titers were evaluated using GFP-carrying recombinant SARS-CoV-2 with spike protein of B.1.1, omicron BA.1, or BA.5. For cellular immunity, peripheral blood mononuclear cells were stimulated with peptides corresponding to spike protein antigens of B.1.1, BA.1, and BA.5; spike-specific CD4/CD8 memory T cells were evaluated using intracellular cytokine staining. The median IgG antibody titers were 7.8 AU/mL in recipients and 143.0 AU/mL in healthy controls (p < 0.0001). Neutralizing antibody titers against all three viral variants were significantly lower in recipients (p < 0.0001). The number of spike-specific CD8 + memory T cells significantly decreased in recipients (p < 0.0001). Twenty recipients and seven healthy controls additionally received a bivalent omicron-containing booster vaccine, and IgG antibody and neutralizing antibody titers increased in both groups; however, the increase was significantly lower in recipients. Recipients did not gain sufficient immunity with a third dose of vaccine, suggesting a need to explore methods other than vaccines.

immunology↗

bioRxiv2020

Enrichment of neurodegenerative microglia signature in brain-derived extracellular vesicles isolated from Alzheimer's disease mouse model

Extracellular vesicles (EVs) are secreted by any neuronal cells in the central nervous system (CNS) for molecular clearance, cellular communications and disease spread in multiple neurodegenerative diseases, including Alzheimers disease (AD), although their exact molecular mechanism is poorly understood. We hypothesize that high-resolution proteomic profiling of EVs separated from animal models of AD would determine the composition of EV contents and their cellular origin. Here, we examined recently developed transgenic mice (CAST.APP/PS1), which express familial AD-linked mutations of amyloid precursor protein (APP) and presenilin-1 (PS1) in the CAST/EiJ mouse strain and develop hippocampal neurodegeneration. Quantitative proteomics analysis of EVs separated from CAST.APP/PS1 and age-matched control mice by tandem mass tag-mass spectrometry identified a total of 3,444 unique proteins, which are enriched in neuron, astrocyte, oligodendrocyte and microglia-specific molecules. CAST.APP/PS1-derived EVs show significant enrichment of Psen1, APP, Itgax, and reduction of Wdr61, Pmpca, Aldh1a2, Calu, Anp32b, Actn4 and Ndufv2 compared to WT-derived EVs, suggesting the involvement of A{beta}-processing complex and disease-associated / neurodegenerative microglia (DAM/MGnD) in EV secretion. In addition, Itgax and Apoe, the DAM/MGnD markers, in EV show a positive correlation with Itgax and Apoe mRNA expression from brain tissue in CAST.APP/PS1 mice. These datasets indicate the significant contribution of A{beta} plaque and neurodegeneration-induced DAM/MGnD microglia for EV secretion in CAST.APP/PS1 mice and shed light on understanding the AD pathogenesis.

neuroscience↗

bioRxiv2020

Amyloid plaque deposition accelerates tau propagation via activation of microglia in a humanized APP mouse model

Microglia have an emerging role in development of tau pathology after amyloid plaque deposition in Alzheimers disease, although it has not been definitively shown. We hypothesize that plaque-associated activated microglia accelerate tau propagation via enhanced phagocytosis and secretion of tau. Here we show that the injection of adeno-associated virus expressing P301L tau mutant into the medial entorhinal cortex (MEC) in humanized APPNL-G-F knock-in mice induces exacerbated tau propagation in the dentate gyrus compared to wild type mice. Depletion of microglia dramatically reduces accumulation of phosphorylated tau (pTau) in the dentate gyrus as well as an extracellular vesicle (EV) marker, Tumor susceptibility gene 101, co-localized in microglia. Mac2+ activated microglia secrete significantly more EVs compared to Mac2- microglia in APPNL-G-F mice in vivo when injected with lentivirus expressing EV reporter gene mEmerald-CD9, suggesting enhanced EV secretion by microglial activation. Our findings indicate that amyloid plaque-mediated acceleration of tau propagation is dependent on activated microglia, which show enhanced EV secretion in vivo.

neuroscience↗