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NLRP3 inflammasome: a novel link between lipoproteins and atherosclerosis

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Pattern recognition receptor-mediated signaling pathways have recently been elucidated to bridge the innate immune system and atherosclerosis. NLRP3 is a member of the NLR family. Upon activation, it initiates IL-1β and IL-18 processing, a key step in the inflammatory process of atherosclerosis.

Material and methods: We used three different types of lipoproteins, ox-LDL, ox-HDL, and HDL, in Thp-1 at the concentration of 50 mg/l, 100 mg/l, and 150 mg/l respectively. Using real-time polymerase chain reaction and western blot, ELISA detected the expression of NLRP3 and downstream cytokines. NLRP3 siRNA was constructed to down-regulate expression of the NLRP3 gene via the RNA interference technique. 150 mg/l of ox-LDL, ox-HDL and HDL was added to the Thp-1 cell line respectively. We observed the changes in the expression of caspase-1, IL-1β and IL-18 when the NLRP3 gene was down-regulated.

Results: Ox-LDL and ox-HDL addition not only increases the expression of NLRP3, but also activates the NLRP3 downstream cytokines and caspase-1 and induces IL-1β and IL-18 secretion. Moreover, the effects of activation and induction are shown to have a dose-dependent manner. Expression of NLRP3 and its downstream inflammatory cytokines is reduced in the presence of HDL (p < 0.05). Furthermore, our data demonstrated that NLRP3 siRNA downregulates NLRP3 expression in mononuclear cells, thus leading to a dramatic reduction in the expression of caspase-1, IL-1β and IL-18 (p < 0.05).

Conclusions: The data suggest that activation of the NLRP3 inflammasome is a critical step in caspase-1 activation and IL-1β and IL-18 secretion. Interference with the NLRP3 inflammasome can significantly inhibit the generation of cytokines, thus impeding the pathogenesis of inflammation.

No MeSH data available.


NLRP3 siRNA interferes with secretion of IL-1β and IL-18 in the supernatant of cell culture*p < 0.05, statistically significant difference compared to the group which did not transfect with NLRP3 siRNA.
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Figure 0005: NLRP3 siRNA interferes with secretion of IL-1β and IL-18 in the supernatant of cell culture*p < 0.05, statistically significant difference compared to the group which did not transfect with NLRP3 siRNA.

Mentions: We further examined the expression of IL-1β and IL-18 in the supernatant of cell culture using ELISA. IL-1β and IL-18 levels were too low to be detected in the groups of control, control transfected with NLRP3 siRNA, HDL and HDL transfected with NLRP3 siRNA. However, the expression of IL-1β and IL-18 is significantly decreased in the groups of ox-LDL and ox-HDL transfected with NLRP3 siRNA respectively. On average, the reduction level is approximately 60–70%. However, there is no statistically significant difference between the groups of ox-LDL and ox-HDL (Figure 5).


NLRP3 inflammasome: a novel link between lipoproteins and atherosclerosis
NLRP3 siRNA interferes with secretion of IL-1β and IL-18 in the supernatant of cell culture*p < 0.05, statistically significant difference compared to the group which did not transfect with NLRP3 siRNA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016581&req=5

Figure 0005: NLRP3 siRNA interferes with secretion of IL-1β and IL-18 in the supernatant of cell culture*p < 0.05, statistically significant difference compared to the group which did not transfect with NLRP3 siRNA.
Mentions: We further examined the expression of IL-1β and IL-18 in the supernatant of cell culture using ELISA. IL-1β and IL-18 levels were too low to be detected in the groups of control, control transfected with NLRP3 siRNA, HDL and HDL transfected with NLRP3 siRNA. However, the expression of IL-1β and IL-18 is significantly decreased in the groups of ox-LDL and ox-HDL transfected with NLRP3 siRNA respectively. On average, the reduction level is approximately 60–70%. However, there is no statistically significant difference between the groups of ox-LDL and ox-HDL (Figure 5).

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Pattern recognition receptor-mediated signaling pathways have recently been elucidated to bridge the innate immune system and atherosclerosis. NLRP3 is a member of the NLR family. Upon activation, it initiates IL-1&beta; and IL-18 processing, a key step in the inflammatory process of atherosclerosis.

Material and methods: We used three different types of lipoproteins, ox-LDL, ox-HDL, and HDL, in Thp-1 at the concentration of 50 mg/l, 100 mg/l, and 150 mg/l respectively. Using real-time polymerase chain reaction and western blot, ELISA detected the expression of NLRP3 and downstream cytokines. NLRP3 siRNA was constructed to down-regulate expression of the NLRP3 gene via the RNA interference technique. 150 mg/l of ox-LDL, ox-HDL and HDL was added to the Thp-1 cell line respectively. We observed the changes in the expression of caspase-1, IL-1&beta; and IL-18 when the NLRP3 gene was down-regulated.

Results: Ox-LDL and ox-HDL addition not only increases the expression of NLRP3, but also activates the NLRP3 downstream cytokines and caspase-1 and induces IL-1&beta; and IL-18 secretion. Moreover, the effects of activation and induction are shown to have a dose-dependent manner. Expression of NLRP3 and its downstream inflammatory cytokines is reduced in the presence of HDL (p &lt; 0.05). Furthermore, our data demonstrated that NLRP3 siRNA downregulates NLRP3 expression in mononuclear cells, thus leading to a dramatic reduction in the expression of caspase-1, IL-1&beta; and IL-18 (p &lt; 0.05).

Conclusions: The data suggest that activation of the NLRP3 inflammasome is a critical step in caspase-1 activation and IL-1&beta; and IL-18 secretion. Interference with the NLRP3 inflammasome can significantly inhibit the generation of cytokines, thus impeding the pathogenesis of inflammation.

No MeSH data available.