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Fig. 6 | Journal of Neuroinflammation

Fig. 6

From: The role of microglia in processing and spreading of bioactive tau seeds in Alzheimer’s disease

Fig. 6

Microglia uptake and process tau, and tau is required for seeding activity independent of other inflammatory factors. a Wild-type microglia (labeled with Iba1, red) incubated with rTg4510 brain lysate take up tau (labeled with HT7 for human tau, green) in vitro after 24 h. b Microglia media or WT microglia CM on its own does not induce seeding (no lysate). However, rTg4510 lysate without microglia incubated for 24 h at 37 °C induces significantly more seeding (p < 0.01) than when rTg4510 lysate is incubated with microglia for 24 h at 37 °C as measured by two-way ANOVA with a Bonferroni post-hoc. c Tau does not have a toxic effect on microglia at the time point tested here, but there is significant toxicity with rTg4510 lysate by LDH assay at 48 h and 72 h. d The first panel examines whether various inflammagens are able to induce tau seeding by themselves or by triggering microglia-induced tau seeding. None of the inflammagens tested had any effect on seeding on their own (white bars) or with microglia (black bars) as measured by a two-way ANOVA with a Bonferroni post-hoc. However, there is a trend (p = 0.0812 and 0.0838, respectively) towards reduced IFD by IL-1β or TNFα without microglia present. The second panel examines whether there is a synergistic effect of applying these same inflammagens with rTg4510 brain lysate with or without microglia present. On its own, rTg4510 brain lysate without microglia or inflammagens induced significantly more seeding (p < 0.001) than any of the other inflammagens with or without microglia. Regardless of inflammagen treatment, the presence of microglia significantly reduced seeding activity and there was no difference between any of the inflammagen-treated microglia (p > 0.9). The presence of inflammagens did not induce microglia to increase or decrease their processing of tau, although the inflammagens by themselves seem to have an effect on the seeding assay itself. *** p < 0.001, ** p < 0.01; n.s. not significant. e Experimental design replicated from Fig. 1. Microglia or media alone was plated at DIV0. At DIV5, half of the media was replaced with fresh media containing rTg4510 lysate containing misfolded tau seeds (τ) inflammagen of varying types (i), or media only (Ø). Twenty-four hours later, media was collected for later application to the seeding assay

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