A chemical screen identifies small molecules that regulate hepcidin expression

AbstractHepcidin, a peptide hormone produced in the liver, decreases intestinal iron absorption and macrophage iron release via effects on ferroportin. Bone morphogenic protein and Stat3 signaling regulate Hepcidin's transcription. Hepcidin is a potential drug target for patients with iron overload syndromes because its levels are inappropriately low in these individuals. To generate a tool for identifying small molecules that modulate Hepcidin expression, we stably transfected human hepatocytes (HepG2) cells with a reporter construct containing 2.7kb of the human Hepcidin promoter upstream of a firefly reporter gene. We used high throughput methods to screen 10,169 chemicals in duplicate for their effect on Hepcidin expression and cell viability. Regulators were identified as chemicals that caused a change >3 standard deviations above or >1 standard deviation below the mean of the other chemicals (z-score >3 or <1), while not adversely affecting cell viability, quantified by fluorescence assay. Following validation assays, we identified 16 chemicals in a broad range of functional classes that promote Hepcidin expression. All of the chemicals identified increased expression of bone morphogenic protein-dependent and/or Stat3-dependent genes, however none of them strongly increased phosphorylation of Smad1,5,8 or Stat3

Omega-3 fatty acids and genome-wide interaction analyses reveal DPP10-pulmonary function association

Rationale: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have anti-inflammatory properties that could benefit adults with comprised pulmonary health. Objective: To investigate n-3 PUFA associations with spirometric measures of pulmonary function tests (PFTs) and determine underlying genetic susceptibility. Methods: Associations of n-3 PUFA biomarkers (a-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid [DPA], and docosahexaenoic acid [DHA]) were evaluated with PFTs (FEV1, FVC, and FEV1/FVC) in meta-analyses across seven cohorts from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium (N=16,134 of European or African ancestry). PFT-associated n-3 PUFAs were carried forward to genome-wide interaction analyses in the four largest cohorts (N=11,962) and replicated in one cohort (N=1,687). Cohort-specific results were combined using joint 2 degree-of-freedom (2df) meta-analyses of SNPassociations and their interactions with n-3PUFAs. Results: DPA and DHA were positively associated with FEV1 and FVC (P < 0.025), with evidence for effect modification by smoking and by sex. Genome-wide analyses identified a novel association of rs11693320-an intronic DPP10 SNP-with FVC when incorporating an interaction with DHA, and the finding was replicated (P-2df = 9.4 x 10(-9) across discovery and replication cohorts). The rs11693320-A allele (frequency, similar to 80%) was associated with lower FVC (P-SNP = 2.1 x 10(-9); beta(SNP) = 2161.0 ml), and the association was attenuated by higher DHA levels (P-SNPxDHA interaction = 2.1x10(-7); beta(SNPxDHA interaction) = 36.2 ml). Conclusions: We corroborated beneficial effects of n-3 PUFAs on pulmonary function. By modeling genome-wide n-3 PUFA interactions, we identified a novel DPP10 SNP association with FVC that was not detectable in much larger studies ignoring this interaction

INVESTIGATING THE CAUSAL ROLE OF VITAMIN D AND OMEGA-3 FATTY ACIDS IN LUNG HEALTH

232 pagesThis dissertation aimed to investigate causality in the associations of vitamin D and omega-3 fatty acids (ω-3 FAs), two nutrients recognized for their immunomodulatory and antiinflammatory properties,with lung health and disease. We used multiple methods with the goal of addressing context-specific limitations and improving causal inference. We first investigated causality in the association of serum vitamin D levels and COVID-19. We conducted a Mendelian Randomization (MR) study of genetic variants associated with vitamin D nutritional status and COVID-19 susceptibility and severity, including severe respiratory infection and hospitalization. We found no evidence for a causal effect of genetically predicted differences in long-term vitamin D nutritional status on susceptibility to and severity of COVID-19 infection. Next, we investigated causality in the association of circulating ω-3 FAs with spirometry-measured long-term lung outcomes. We applied two complementary approaches: 1) a longitudinal study of plasma phospholipid ω-3 FAs, lung function decline, and incident airway obstruction, and 2) an MR study of genetically predicted ω-3 FAs and lung function parameters. The longitudinal study found that higher ω-3 FAs were associated with an attenuation in lung function decline and reduced risk of airway obstruction, with the strongest effects for docosahexaenoic acid (DHA). The MR study corroborated these findings, with evidence for positive effects of genetically predicted ω-3 FAs on lung function parameters. Lastly, we studied the evidence for the efficacy of vitamin D supplementation in early life for preventing childhood asthma. We conducted a systematic review and meta-analysis of randomized controlled trials of vitamin D supplementation in pregnant or lactating women or young children. We identified 17 studies meeting the eligibility criteria for the review, and found moderate-certainty evidence that vitamin D supplementation in pregnancy or early childhood reduces the risk of childhood asthma or wheeze, and may also reduce the risk of atopic dermatitis and decrease markers of allergic sensitization, both of which are thought to contribute to the development of asthma. Ultimately the studies comprising this dissertation demonstrate the application of different methods to improve causal inference for nutrition and lung health. The findings could help inform public health strategies to prevent lung disease.2024-09-0

A politics of indifference: reading Cavarero, Rancière and Arendt

This article compares the accounts of politics found in the work of Adriana Cavarero and Jacques Rancière. It argues that when Cavarero offers a formal account of politics she thinks politics with Hannah Arendt and thus falls foul of Rancière's critique of Arendt. However, Cavarero offers the sense of another account of politics in her reading of Penelope in In Spite of Plato, one that not only avoids Rancière's critique but demonstrates the limits of Rancière's own account of politics. Cavarero makes tangible a sense of a politics indifferent to extant orders, something that is difficult to discern in Rancière given his insistence that politics makes visible forms of existence that could not otherwise be seen, said or heard

Nicotinamide N‐methyltransferase expression decreases in iron overload, exacerbating toxicity in mouse hepatocytes

Iron overload causes the generation of reactive oxygen species that can lead to lasting damage to the liver and other organs. The goal of this study was to identify genes that modify the toxicity of iron overload. We studied the effect of iron overload on the hepatic transcriptional and metabolomic profile in mouse models using a dietary model of iron overload and a genetic model, the hemojuvelin knockout mouse. We then evaluated the correlation of nicotinamide N‐methyltransferase (NNMT) expression with body iron stores in human patients and the effect of NNMT knockdown on gene expression and viability in primary mouse hepatocytes. We found that iron overload induced significant changes in the expression of genes and metabolites involved in glucose and nicotinamide metabolism and that NNMT, an enzyme that methylates nicotinamide and regulates hepatic glucose and cholesterol metabolism, is one of the most strongly down‐regulated genes in the liver in both genetic and dietary iron overload. We found that hepatic NNMT expression is inversely correlated with serum ferritin levels and serum transferrin saturation in patients who are obese, suggesting that body iron stores regulate human liver NNMT expression. Furthermore, we demonstrated that adenoviral knockdown of NNMT in primary mouse hepatocytes exacerbates iron‐induced hepatocyte toxicity and increases expression of transcriptional markers of oxidative and endoplasmic reticulum stress, while overexpression of NNMT partially reversed these effects. Conclusion:: Iron overload alters glucose and nicotinamide transcriptional and metabolic pathways in mouse hepatocytes and decreases NNMT expression, while NNMT deficiency worsens the toxic effect of iron overload. For these reasons, NNMT may be a drug target for the prevention of iron‐induced hepatotoxicity. (Hepatology Communications 2017;1:803–815

A systematic analysis of protein-altering exonic variants in chronic obstructive pulmonary disease

Genome-wide association studies (GWASs) have identified regions associated with chronic obstructive pulmonary disease (COPD). GWASs of other diseases have shown an approximately 10-fold overrepresentation of nonsynonymous variants, despite limited exonic coverage on genotyping arrays. We hypothesized that a large-scale analysis of coding variants could discover novel genetic associations with COPD, including rare variants with large effect sizes. We performed a meta-analysis of exome arrays from 218,399 controls and 33,851 moderate-to-severe COPD cases. All exome-wide significant associations were present in regions previously identified by GWAS. We did not identify any novel rare coding variants with large effect sizes. Within GWAS regions on chromosomes 5q, 6p, and 15q, four coding variants were conditionally significant (p < 0.00015) when adjusting for lead GWAS SNPs. A common GSDMB splice variant (rs11078928) previously associated with decreased risk for asthma, was nominally associated with decreased risk for COPD (MAF = 0.46, p=1.8e-4). Two stop variants in CCHCR1, a gene involved in regulating cell proliferation, were associated with COPD (both p < 0.0001). The SERPINA1 Z allele was associated with a random effects odds ratio of 1.43 for COPD (95% CI: 1.17-1.74), though with marked heterogeneity across studies. Overall, COPD-associated exonic variants were identified in genes involved in DNA methylation, cell-matrix interactions, cell proliferation, and cell death. In conclusion, we performed the largest exome array meta-analysis of COPD to date and identified potential functional coding variants. Future studies are needed to identify rarer variants, and further define the role of coding variants in COPD pathogenesis

Paradoxes of Constitutional Democracy

Drawing on the work of Frank Michelman and Jürgen Habermas, I outline two interconnected paradoxes of constitutional democracy. The paradox of the founding prevents a purely democratic constitution from being founded, because the procedures needed to secure its legitimacy cannot be spontaneously self-generated. It displays an infinite regression of procedures presupposing procedures. The paradox of dynamic indeterminacy heads off any attempt to resolve this problem through constitutional amendment. It shows that a developing constitution needs some standard to guide it towards legitimacy. Without such a standard, constitutional reform will be aimlessly indeterminate. After rejecting proposed solutions to these paradoxes based on political contestation, culture, and “constitutional patriotism,” I outline an alternative based on the ideas of dynamic constitutionalism and reflexive citizenship. This solution draws on material, structural, positive characteristics of the law to show how a dynamically evolving constitution can promote its own legitimacy from within, resolving both paradoxes in one stroke