TABLE 2.

Summary of neuroprotective and neurotoxic effects of microglia-derived exosomes with identified cargo.

Role	Stimuli/disease	Cargo	Effect observed	References
	PD	α-Synuclein	Increases Iba-1 expression, microglia number, and arborization	Xia et al., 2019
			Increases the aggregated form of α-synuclein in neurons
	PFF and LPS	α-Synuclein	Increases dopaminergic neuron degeneration	Guo et al., 2020
	α-Synuclein	MHC-II and TNF-α	Increases neuronal cell death	Chang et al., 2013
	Tau and LPS or ATP	Tau	Increases tau dissemination on neurons	Asai et al., 2015; Clayton et al., 2021
	LPS and Mn+2	ASC	Increases pro-IL-1β and NLRP3 in microglia	Sarkar et al., 2019
	Th1 cytokines and LPS	miR-146a-5p	Reduces the expression of Syt1 and Nlg1	Prada et al., 2018
			Reduces dendritic spine density
Neurotoxic	Stretch injury	miR-5121	Reduces the expression of synaptophysin, PSD-95, GluR-1	Zhao et al., 2021
			Reduces dendritic spine density
	Ethanol	CD13, MMP2 and C1q	Increases neuronal cell death?	Mukherjee et al., 2020
	Cerebral ischemia	TNF-α and COX-2	Increases neuroinflammation	Gao et al., 2020
	OGD	PDE1-B	Induces neuronal cell death	Zang et al., 2020
	Brain extract from mTBI/	miR-124-3p	Reduces inflammation	Huang et al., 2018; Li et al., 2019; Ge et al., 2020
	Over-expression of miR-124-3p		Increases the expression of BDNF and neurogranin
Neuroprotective			Increases neurite length and number of branches
			Reduces Rela, VILIP-1, Aβ, and APP
	IL-4	miR-124	Protects neurons from OGD induced cell death	Song et al., 2019
	IL-4	miR-137	Protects neurons from OGD induced cell death	Zhang et al., 2021
Regulatory	–	AEA	Inhibits presynaptic transmission in GABAergic neurons	Gabrielli et al., 2015