biostudies-literatureLe HGNational Research Foundation of Korea13623https://www.ebi.ac.uk/biostudies/studies/S-EPMC10487526biostudies-literatureUnknown24(17)Extracellular vesicles (EVs) of protozoan parasites have diverse biological functions that are essential for parasite survival and host-parasite interactions. In this study, we characterized the functional properties of EVs from <i>Naegleria fowleri</i>, a pathogenic amoeba that causes a fatal brain infection called primary amoebic meningoencephalitis (PAM). <i>N. fowleri</i> EVs (NfEVs) have been shown to be internalized by host cells such as C6 glial cells and BV-2 microglial cells without causing direct cell death, indicating their potential roles in modulating host cell functions. NfEVs induced increased expression of proinflammatory cytokines and chemokines such as TNF-α, IL-1α, IL-1β, IL-6, IL-17, IFN-γ, MIP-1α, and MIP-2 in BV-2 microglial cells; these increases were initiated via MyD88-dependent TLR-2/TLR-4. The production levels of proinflammatory cytokines and chemokines in NfEVs-stimulated BV-2 microglial cells were effectively downregulated by inhibitors of MAPK, NF-κB, or JAK-STAT. Phosphorylation levels of JNK, p38, ERK, p65, JAK-1, and STAT3 were increased in NfEVs-stimulated BV-2 microglial cells but were effectively suppressed by each corresponding inhibitor. These results suggest that NfEVs could induce proinflammatory immune responses in BV-2 microglial cells via the NF-κB-dependent MAPK and JAK-STAT signaling pathways. Taken together, these findings suggest that NfEVs are pathogenic factors involved in the contact-independent pathogenic mechanisms of <i>N. fowleri</i> by inducing proinflammatory immune responses in BV-2 microglial cells, further contributing to deleterious inflammation in infected foci by activating subsequent inflammation cascades in other brain cells.International journal of molecular sciences<i>Naegleria fowleri</i> Extracellular Vesicles Induce Proinflammatory Immune Responses in BV-2 Microglial Cells.PMC10487526NRF-2018R1D1A1B07048097NRF-2021R1A2C1091855Na BKKang JMVo TCYoo WGLe HGfalse<i>Naegleria fowleri</i> Extracellular Vesicles Induce Proinflammatory Immune Responses in BV-2 Microglial Cells.Extracellular vesicles (EVs) of protozoan parasites have diverse biological functions that are essential for parasite survival and host-parasite interactions. In this study, we characterized the functional properties of EVs from <i>Naegleria fowleri</i>, a pathogenic amoeba that causes a fatal brain infection called primary amoebic meningoencephalitis (PAM). <i>N. fowleri</i> EVs (NfEVs) have been shown to be internalized by host cells such as C6 glial cells and BV-2 microglial cells without causing direct cell death, indicating their potential roles in modulating host cell functions. NfEVs induced increased expression of proinflammatory cytokines and chemokines such as TNF-α, IL-1α, IL-1β, IL-6, IL-17, IFN-γ, MIP-1α, and MIP-2 in BV-2 microglial cells; these increases were initiated via MyD88-dependent TLR-2/TLR-4. The production levels of proinflammatory cytokines and chemokines in NfEVs-stimulated BV-2 microglial cells were effectively downregulated by inhibitors of MAPK, NF-κB, or JAK-STAT. Phosphorylation levels of JNK, p38, ERK, p65, JAK-1, and STAT3 were increased in NfEVs-stimulated BV-2 microglial cells but were effectively suppressed by each corresponding inhibitor. These results suggest that NfEVs could induce proinflammatory immune responses in BV-2 microglial cells via the NF-κB-dependent MAPK and JAK-STAT signaling pathways. Taken together, these findings suggest that NfEVs are pathogenic factors involved in the contact-independent pathogenic mechanisms of <i>N. fowleri</i> by inducing proinflammatory immune responses in BV-2 microglial cells, further contributing to deleterious inflammation in infected foci by activating subsequent inflammation cascades in other brain cells.2023-01-01T00:00:00Z2023 Sep2025-04-22T04:15:34.189Z2025-04-05T20:55:04.854ZS-EPMC104875263768642910.3390/ijms241713623