NLRP3 Inflammasome Activation in THP-1 Target Cells Triggered by Pathogenic Naegleria fowleri.
Naegleria fowleri, known as the brain-eating amoeba, causes acute primary amoebic meningoencephalitis. During swimming and other recreational water activities, N. fowleri trophozoites penetrate the nasal mucosa and invade the olfactory bulbs, resulting in intense inflammatory reactions in the forebrain tissue. To investigate what kinds of inflammasome molecules are expressed in target cells due to N. fowleri infection, human macrophage cells (THP-1 cells) were cocultured with N. fowleri trophozoites in a noncontact system, and consequently, interleukin-1β (IL-1β) production was estimated. Caspase-1 activation and IL-1β production from THP-1 cells by Western blotting and the culture supernatant by enzyme-linked immunosorbent assay analysis were observed at 3 h after cocultivation. In addition, the increased expression of ASC and NLRP3, which make up an inflammasome complex, was also observed at 3 h after cocultivation. To confirm the caspase-1 activation and IL-1β production via the NLRP3 inflammasome in THP-1 cells triggered by N. fowleri trophozoites, THP-1 cells were pretreated with several inhibitors. The inhibition assay showed that CA-074 (a cathepsin B inhibitor), glybenclamide (an NLRP3 molecule inhibitor), and N-benzyloxycarbony-Val-Ala-Asp(O-methyl)-fluoromethylketone (Z-VAD-FMK; a caspase-1 inhibitor) reduced the levels of caspase-1 activation and IL-1β production from THP-1 cells. This study suggests that N. fowleri infection induces the NLRP3 inflammasome, which activates caspase-1 and subsequently produces IL-1β, thus resulting in inflammation.
Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, Republic of Korea Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea.
Jong-Hyun
JH
Kim
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Hae-Jin
HJ
Sohn
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Jong-Kyun
JK
Yoo
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Heekyoung
H
Kang
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Gi-Sang
GS
Seong
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Yong-Joon
YJ
Chwae
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Kyongmin
K
Kim
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea.
Sun
S
Park
Department of Microbiology, Ajou University School of Medicine, Suwon, Republic of Korea Department of Biomedical Science, Graduate School of Ajou University, Suwon, Republic of Korea hjshin@ajou.ac.kr.
Ho-Joon
HJ
Shin
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D020170:Caspase 1 / Q000378:metabolism; D045744:Cell Line, Tumor; D004151:Dipeptides / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D058847:Inflammasomes / Q000187:drug effects / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein / Q000378:metabolism*; D016848:Naegleria fowleri / Q000187:drug effects / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D004151:Dipeptides; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C068250:N-(3-propylcarbamoyloxirane-2-carbonyl)-isoleucyl-proline; D020170:Caspase 1; D005905:Glyburide