Lead Nitrate Induces Inflammation and Apoptosis in Rat Lungs Through the Activation of NF-κB and AhR Signaling Pathways

Abstract

Lead (Pb) is one of the most frequent hazardous air contaminants, where the lungs are particularly vulnerable to its toxicity. However, the Pb distribution and its impact on lung inflammation/apoptosis and particularly the involvement of nuclear factor kappa B (NF-κB) and aryl hydrocarbon receptor (AhR) signaling pathways in Pb-induced lung toxicity have not yet been fully investigated. Adult male Wistar albino rats were exposed to Pb nitrate 25, 50, and 100 mg/kg b.w. orally for 3 days. The histopathological changes of several rat organs were analyzed using hematoxylin and eosin staining. The concentrations of Pb ion in different organ tissues were quantified using inductive coupled plasma mass spectrometry, while gas chromatography-mass spectrometry was used to identify organic compounds. The changes in the mRNA and protein expression levels of inflammatory and apoptotic genes in response to Pb exposure were quantified by using RT-PCR and Western blot analyses, respectively. Treatment of rats with Pb for three consecutive days significantly increased the accumulation of Pb in lung tissues causing severe interstitial inflammation. Pb treatment also increased the percentage of lung apoptotic cells and modulated apoptotic genes (Bc2, p53, and TGF-α), inflammatory markers (IL-4, IL-10, TNF-α), and oxidative stress biomarkers (iNOS, CYP1A1, EphX) in rat lung tissues. These effects were associated with a significant increase in organic compounds, such as 3-nitrotyrosine and myeloperoxidase, and some inorganic elements, such as selenium. Importantly, the Pb-induced lung inflammation and apoptosis were associated with a proportional increase in the expression of NF-κB and AhR mRNAs and proteins. These findings clearly show that Pb induces severe inflammation and apoptosis in rat lungs and suggest that NF-κB and AhR may play a role in Pb-induced lung toxicity.

Exogenous surfactant reduces inflammation and redox imbalance in rats under prone or supine mechanical ventilation

“…For the analysis, the same strategy was applied as used by Attafi et al . 38 Triplicate analyses on the mRNA expression (fold change) were performed normalizing the results with the constitutive gene β-actin (ΔCt).…”

“…The efficiency of each primer pair was evaluated by serial dilutions of cDNA according to the protocol developed by PE Applied Biosystems. In order to evaluate expression of the inflammatory markers IL-6, IL-8, NF-κB, and TNF-α, qRT-PCR was utilized using the same specific primers used by Attafi et al 38 (Table 1). For the analysis, the same strategy was applied as used by Attafi et al .…”

“…The efficiency of each primer pair was evaluated by serial dilutions of cDNA according to the protocol developed by PE Applied Biosystems. In order to evaluate expression of the inflammatory markers IL-6, IL-8, NF-κB, and TNF-α, qRT-PCR was utilized using the same specific primers used by Attafi et al 38 (Table 1). For the analysis, the same strategy was applied as used by Attafi et al 38 Triplicate analyses on the mRNA expression (fold change) were performed normalizing the results with the constitutive gene β-actin (ΔCt).…”

Pb(NO3)2 induces cell apoptosis through triggering of reactive oxygen species accumulation and disruption of mitochondrial function via SIRT3/SOD2 pathways

“…6,9 Many human and experimental animal studies have revealed that exposure to Pb causes epigenetic changes and microenvironmental alterations, including microRNA dysregulation, DNA methylation, cell autophagy and apoptosis, immune cells dysfunction, cytokines production, reactive oxygen species (ROS) accumulation, and tumorassociated signaling pathway activation. [10][11][12] Oxidative stress represents the major mechanism of Pb-induced toxicity through generating ROS as well as inhibiting antioxidative responses. 5 Using antioxidant flavonoid luteolin improved Pb-induced oxidative damage and cell death by eliminating lipid peroxidation and elevating antioxidant molecules, such as superoxide dismutase (SOD), catalase, glutathionedisulfide reductase (GSR), glutathione peroxidase, and glutathione (GSH) in rat hepatocytes, indicating the critical role of oxidative responses resulted from Pb exposure.…”

“…13 Although Pb stimulation has reported to increase cell death by regulating oxidative stress biomarkers, apoptotic genes, and inflammatory factors in human lung cancer HL-60 cells 14 and rat lung. 10 Moreover, the excess ROS accumulation induces mitochondria DNA damage which causes the loss of mitochondrial membrane potential (ΔΨm) and cell death in brain, kidney, and lung. 15,16 However, the upstream regulators of ROS production are unclear.…”