Ambient PM2.5 Components Are Associated With Bone Strength: Evidence From a China Multi-Ethnic Study

Multiomics Analysis of PCB126's Effect on a Mouse Chronic-Binge Alcohol Feeding Model

BACKGROUND

Environmental pollutants, including polychlorinated biphenyls (PCBs) have been implicated in the pathogenesis of liver disease. Our group recently demonstrated that PCB126 promoted steatosis, hepatomegaly, and modulated intermediary metabolism in a rodent model of alcohol-associated liver disease (ALD).

OBJECTIVE

To better understand how PCB126 promoted ALD in our previous model, the current study adopts multiple omics approaches to elucidate potential mechanistic hypotheses.

METHODS

Briefly, male C57BL/6J mice were exposed to 0.2 mg / kg polychlorinated biphenyl (PCB) 126 or corn oil vehicle prior to ethanol (EtOH) or control diet feeding in the chronic-binge alcohol feeding model. Liver tissues were collected and prepared for mRNA sequencing, phosphoproteomics, and inductively coupled plasma mass spectrometry for metals quantification.

RESULTS

Principal component analysis showed that PCB126 uniquely modified the transcriptome in EtOH-fed mice. EtOH feeding alone resulted in > 4,000 differentially expressed genes (DEGs), and PCB126 exposure resulted in more DEGs in the EtOH-fed group (907 DEGs) in comparison with the pair-fed group (503 DEGs). Top 20 significant gene ontology (GO) biological processes included "peptidyl tyrosine modifications," whereas top 25 significantly decreasing GO molecular functions included "metal/ion/zinc binding." Quantitative, label-free phosphoproteomics and western blot analysis revealed no major significant PCB126 effects on total phosphorylated tyrosine residues in EtOH-fed mice. Quantified hepatic essential metal levels were primarily significantly lower in EtOH-fed mice. PCB126-exposed mice had significantly lower magnesium, cobalt, and zinc levels in EtOH-fed mice.

DISCUSSION

Previous work has demonstrated that PCB126 is a modifying factor in metabolic dysfunction-associated steatotic liver disease (MASLD), and our current work suggests that pollutants also modify ALD. PCB126 may, in part, be contributing to the malnutrition aspect of ALD, where metal deficiency is known to contribute and worsen prognosis. https://doi.org/10.1289/EHP14132.

Tumor necrosis factor mediates the impact of PM2.5 on bone mineral density: Inflammatory proteome Mendelian randomization and colocalization analyses

To assess the causal effect of particulate matter 2.5 (PM2.5) on human bone mineral density (BMD) and to explore the possible mechanism and proportion mediated by inflammation-related protein. The genetic correlation between PM2.5 and BMD was assessed using the Linkage Disequilibrium Score (LDSC), and the causal effect between PM2.5 and BMD was assessed by two-sample Mendelian randomization (TSMR). A 2-step Mendelian randomization (MR) approach was employed to evaluate the potential role of inflammation-associated protein as the mediator in the causal association between PM2.5 and BMD. The multivariate Mendelian randomization (MVMR) study was designed to perform mediation analyses, exclude possible confounders and calculate the proportion of mediation. Subsequently, we used Bayesian colocalization analysis to consolidate the MR results. Finally, using drug-target MR design, we evaluated the potential repurposing of tumor necrosis factor (TNF) inhibitors for the treatment of osteoporosis (OP). The results of the analyses show that BMD is negatively influenced by PM2.5 (Inverse variance weighted [IVW] beta [β] = -0.288, 95% confidence interval [CI]: -0.534 - -0.042, P < 0.05). PM2.5 has a positive causal association with TNF (IVW β = 1.564, 95% CI: 0.155 - 2.973, P < 0.05) and a negative causal association with protachykinin-1 (TAC-1) (IVW β = -1.654, 95% CI: -3.063 - -0.244, P < 0.05). TNF has a negative causal association with BMD (Wald ratio β = -0.082, 95% CI: -0.165 - 0.000, P < 0.05) and TAC-1 has a positive causal association with BMD (IVW β = 0.042, 95% CI: 0.007 - 0.077, P < 0.05). After adjusting TNF and TAC-1, PM2.5 has no causal association with BMD (IVW β = -0.200, 95% CI: -0.579 - 0.179, P > 0.05). After adjusting PM2.5 and TAC-1, there was still a negative causal association between TNF and BMD (IVW β = -0.089, 95% CI: -0.166 - -0.012, P < 0.05). In the final drug-target MR study, the protective effect of TNF/TNF receptor 1 (TNFR1) inhibition on BMD was observed. For every 10% decrease of circulating C-reactive protein (CRP) achieved by TNF/TNF receptor 1 (TNFR1) blockade, β was 0.540 (95% CI: 0.040-1.040) for BMD. We found a negative causal association between PM2.5 and BMD and that causal association was mediated by TNF. The results of drug-target MR do support TNFR1 as a promising target for OP prevention among the general population.