Mechanism of curcumin in inhibiting silica-induced NLRP3 inflammasome activation in mouse alveolar macrophages
10.11763/j.issn.2095-2619.2020.02.001
- Author:
Nannan SONG
1
;
Zhongjun DU
;
Qiang JIA
;
Shangya CHEN
;
Wenwen ZHU
;
Xu YANG
;
Shanshan HOU
;
Hua SHAO
1
Author Information
1. Shandong University of Traditional Chinese Medicine Jinan, Shandong 250355, China
- Publication Type:Journal Article
- Keywords:
Curcumin;
Silica;
Alveolar macrophages;
NLRP3;
Caspase-1;
Interleukin;
Nuclear factor-κB;
Mouse
- From:
China Occupational Medicine
2020;47(02):121-128
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE: To explore the molecular mechanism of curcumin in inhibiting the nucleotide-binding oligomerization domain like receptor family pyrin domain-containing(NLRP3) inflammatory bodies induced by silica(SiO_2) in mouse alveolar macrophages(AM). METHODS: AMs were isolated from the bronchoalveolar lavage fluid of specific pathogen free C57 BL/6 mice and divided into 6 groups. Among them, the AM of the control group received no stimulation; the AM in the SiO_2 stimulation group was stimulated with SiO_2 suspension at the final mass concentration of 50 mg/L; the AM in nuclear factor(NF-κB)inhibition group was pretreated with 5-(4-fluorophenyl)-2-urea-thiophene-3-formamide with a final concentration of 200 nmoL/L for 1 hour, the AM in the low-, medium-and high-dose curcumin groups were pretreated with curcumin with the final concentrations of 20, 40 and 50 μmol/L for 1 hour, respectively, and then stimulated with SiO_(2 )suspension with a final concentration of 50 mg/L. Samples were collected after 6 hours of incubation. The mRNA expression of NLRP3 inflammasome related genes such as NLRP3, Caspase-1 and interleukin(IL)-1β was detected by real-time fluorescence quantitative polymerase chain reaction. The secretion level of maturation IL-1β(mIL-1β) and IL-18 in AM was detected by enzyme-linked immunosorbent assay. The protein expression and secretion level of cleaved Caspase-1, precursor-IL-1β(pro-IL-1β) and mIL-1β were analyzed by Western blotting. RESULTS: The mRNA relative expression of NLRP3, Caspase-1 and IL-1β, and the secretion levels of mIL-1β and IL-18, and the protein relative expression of Caspase-1, pro-IL-1β and mIL-1β, as well as the secretion levels of cleaved Caspase-1 and mIL-1β increased in the SiO_2 stimulated group compared with the control group(P<0.05). Except for the relative expression and the secretion level of cleaved Caspase-1, the other 8 indexes in the NF-κB inhibition group were lower than that in the SiO_2 stimulation group(P<0.05). Except for the relative expression of cleaved Caspase-1 and mIL-1β proteins in the low-dose curcumin group, the relative expression of all the above 10 indexes was lower in the three curcumin treated groups than that in the SiO_2 stimulation group(P<0.05). In addition, all the above indexes decreased with the increase of curcumin intervention dose(P<0.05). The mRNA relative expression of NLRP3 and IL-1β, and the protein relative expression of pro-IL-1β increased in the medium-dose curcumin group(P<0.05), the secretion levels of mIL-1β and IL-18, as well as the protein relative expression and secretion levels of cleaved Caspase-1 and mIL-1β decreased(P<0.05), compared with the NF-κB inhibition group. CONCLUSION: Curcumin can inhibit SiO_2-induced AM NLRP3 inflammasome activation in a dose-response relationship. This process may be related to the inhibition of NF-κB signaling pathway by curcumin and the down-regulating NLRP3 inflammasome-related genes at the transcriptional level. The important mechanism may be that curcumin directly blocks the activation, assembly, and downstream shearing of NLRP3 in inflammasomes.
