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Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages
Published on: May 21, 2018
Molybdenum and/or cadmium induce NLRP3 inflammasome production by causing mitochondria-associated endoplasmic
Huifeng Chang1, Fan Yang1, He Bai2
1Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, No. 1101 Zhimin Avenue, Economic and Technological Development District, Nanchang, 330045, Jiangxi, PR China.
Abstract:
Accumulation of the heavy metals molybdenum (Mo) and cadmium (Cd) in the liver can induce organelle damage and inflammation, resulting in hepatotoxicity. The effect of Mo and/or Cd on sheep hepatocytes was investigated by determining the relationship between the mitochondria-associated endoplasmic reticulum membrane (MAM) and NLRP3 inflammasome. Sheep hepatocytes were divided into four groups: the control group, Mo group (600 μM Mo), Cd group (4 μM Cd) and Mo + Cd group (600 μM Mo+4 μM Cd). The results showed that Mo and/or Cd exposure increased the levels of lactate dehydrogenase (LDH) and nitric oxide (NO) in the cell culture supernatant, elevated the levels of intracellular Ca2+ and mitochondrial Ca2+, downregulated the expression of MAM-related factors (IP3R, GRP75, VDAC1, PERK, ERO1-α, Mfn1, Mfn2, ERP44), shortened the length of the MAM and reduced the formation of the MAM structure, eventually causing MAM dysfunction. Moreover, the expression levels of NLRP3 inflammasome-related factors (NLRP3, Caspase1, IL-1β, IL-6, TNF-α) were also dramatically increased after Mo and Cd exposure, triggering NLRP3 inflammasome production. However, an IP3R inhibitor, 2-APB treatment significantly alleviated these changes. Overall, the data indicate that Mo and Cd coexposure leads to structural disruption and dysfunction of MAM, disrupts cellular Ca2+ homeostasis, and increases NLRP3 inflammasome production in sheep hepatocytes. However, the inhibition of IP3R alleviates NLRP3 inflammasome production induced by Mo and Cd.
Insights
Heavy metals molybdenum (Mo) and cadmium (Cd) cause liver damage by disrupting mitochondria-associated endoplasmic reticulum membrane (MAM) structure and function. This disruption triggers NLRP3 inflammasome activation, leading to hepatotoxicity, but IP3R inhibition can mitigate this response.
Area of Science:
- Toxicology
- Cell Biology
- Hepatology
Background:
- Heavy metals like molybdenum (Mo) and cadmium (Cd) are known hepatotoxins.
- Organelle damage and inflammation are key mechanisms in heavy metal-induced liver injury.
- The mitochondria-associated endoplasmic reticulum membrane (MAM) plays a crucial role in cellular homeostasis and stress response.
Purpose of the Study:
- To investigate the effects of Mo and/or Cd exposure on sheep hepatocytes.
- To determine the relationship between MAM dysfunction and NLRP3 inflammasome activation in response to heavy metal exposure.
- To evaluate the potential of IP3R inhibition in mitigating heavy metal-induced hepatotoxicity.
Main Methods:
- Sheep hepatocytes were exposed to Mo, Cd, or both.
- Cell viability was assessed by measuring lactate dehydrogenase (LDH) and nitric oxide (NO) release.
- Intracellular and mitochondrial calcium (Ca2+) levels were measured.
- Expression of MAM-related proteins and NLRP3 inflammasome components was analyzed.
- The effect of an IP3R inhibitor (2-APB) was evaluated.
Main Results:
- Mo and/or Cd exposure increased LDH and NO levels, indicating cell damage.
- Exposure elevated intracellular and mitochondrial Ca2+ concentrations.
- Expression of MAM-related factors was downregulated, leading to MAM structural disruption and dysfunction.
- NLRP3 inflammasome components (NLRP3, Caspase-1, IL-1β, IL-6, TNF-α) were significantly upregulated.
- Treatment with the IP3R inhibitor 2-APB ameliorated MAM dysfunction and NLRP3 inflammasome activation.
Conclusions:
- Coexposure to Mo and Cd induces structural disruption and dysfunction of the MAM in sheep hepatocytes.
- Heavy metal-induced MAM dysfunction disrupts cellular Ca2+ homeostasis and promotes NLRP3 inflammasome activation.
- Inhibition of IP3R offers a potential therapeutic strategy to alleviate heavy metal-induced hepatotoxicity by reducing NLRP3 inflammasome activation.
