Faculty Bibliography

BACKGROUND:Kidney reabsorption of magnesium (Mg) is essential for homeostasis. OBJECTIVES:We developed and validated models with the kidney reabsorption-related magnesium depletion score (MDS) to predict states of magnesium deficiency and disease outcomes. METHODS:MDS was validated in predicting body magnesium status among 77 adults (aged 62 ± 8 y, 51% men) at high risk of magnesium deficiency in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (registered at clinicaltrials.gov as NCT01105169) using the magnesium tolerance test (MTT). We then validated MDS for risk stratification and for associations with inflammation and mortality among >10,000 US adults (weighted: aged 48 ± 0.3 y, 47% men) in the NHANES, a nationally representative study. A proportional hazards regression model was used for associations between magnesium intake and the MDS with risks of total and cardiovascular disease (CVD) mortality. RESULTS:In the PPCCT, the area under the receiver operating characteristic (ROC) curve (AUC) for magnesium deficiency was 0.63 (95% CI: 0.50, 0.76) for the model incorporating the MDS with sex and age compared with 0.53 (95% CI: 0.40, 0.67) for the model with serum magnesium alone. In the NHANES, mean serum C-reactive protein significantly increased with increasing MDS (P-trend < 0.01) after adjusting for age and sex and other covariates, primarily among individuals with magnesium intake less than the Estimated Average Requirement (EAR; P-trend < 0.05). Further, we found that low magnesium intake was longitudinally associated with increased risks of total and CVD mortality only among those with magnesium deficiency predicted by MDS. MDS was associated with increased risks of total and CVD mortality in a dose-response manner only among those with magnesium intake less than the EAR. CONCLUSIONS:The MDS serves as a promising measure in identifying individuals with magnesium deficiency who may benefit from increased intake of magnesium to reduce risks of systemic inflammation and CVD mortality. This lays a foundation for precision-based nutritional interventions.

The gut microbiota plays an important role in human health and disease. Stool, rectal swab and rectal mucosal tissue samples have been used in individual studies to survey the microbial community but the consequences of using these different sample types are not completely understood. In this study, we report differences in stool, rectal swab and rectal mucosal tissue microbial communities with shotgun metagenome sequencing of 1397 stool, swab and mucosal tissue samples from 240 participants. The taxonomic composition of stool and swab samples was distinct, but less different to each other than mucosal tissue samples. Functional profile differences between stool and swab samples are smaller, but mucosal tissue samples remained distinct from the other two types. When the taxonomic and functional profiles were used for inference in association with host phenotypes of age, sex, body mass index (BMI), antibiotics or non-steroidal anti-inflammatory drugs (NSAIDs) use, hypothesis testing using either stool or rectal swab gave broadly significantly correlated results, but inference performed on mucosal tissue samples gave results that were generally less consistent with either stool or swab. Our study represents an important resource for determination of how inference can change for taxa and pathways depending on the choice of where to sample within the human gut.

Vaccination intent is foundational for effective COVID-19 vaccine campaigns. To understand factors and attitudes influencing COVID-19 vaccination intent in Black and White adults in the US south, we conducted a mixed-methods cross-sectional survey of 4512 adults enrolled in the Southern Community Cohort Study (SCCS), an ongoing study of racial and economic health disparities. Vaccination intent was measured as "If a vaccine to prevent COVID-19 became available to you, how likely are you to choose to get the COVID-19 vaccination?" with options of "very unlikely," "somewhat unlikely," "neither unlikely nor likely," "somewhat likely," and "very likely." Reasons for intent, socio-demographic factors, preventive behaviors, and other factors were collected. 46% of participants had uncertain or low intent. Lower intent was associated with female gender, younger age, Black race, more spiritual/religious, lower perceived COVID-19 susceptibility, living in a greater deprivation area, lower reading ability, and lack of confidence in childhood vaccine safety or COVID-19 vaccine effectiveness or safety (p < .05 for all). Most factors were present in all racial/gender groups. Contextual influences, vaccine/vaccination specific issues, and personal/group influences were identified as reasons for low intent. Reasons for higher intent included preventing serious illness, life returning to normal, and recommendation of trusted messengers. Hesitancy was complex, suggesting tailored interventions may be required to address low intent.

OBJECTIVES:The viral entry of SARS-CoV-2 requires host-expressed TMPRSS2 to facilitate the viral spike protein priming. This study aims to test the hypothesis that magnesium (Mg) treatment leads to DNA methylation changes in TMPRSS2. METHODS:This study is nested within the Personalized Prevention of Colorectal Cancer Trial, a double-blind 2 × 2 factorial randomized controlled trial, which enrolled 250 participants from Vanderbilt University Medical Center. RESULTS:We found that 12 wk of personalized Mg treatment significantly increased 5-methylcytosine methylation at cg16371860 (TSS1500, promoter) by 7.2% compared to the placebo arm (decreased by 0.1%) in those ages < 65 y. The difference remained statistically significant after adjusting for age, sex, and baseline methylation as well as correction for false discovery rate (adjusted P = 0.014). Additionally, Mg treatment significantly reduced 5-hydroxymethylcytosine levels at cg26337277 (close proximity to TSS200 and the 5' untranslated region, promoter) by 2.3% compared to an increase of 7.1% in the placebo arm after adjusting for covariates in those ages < 65 y (P = 0.003). The effect remained significant at a false discovery rate of 0.10 (adjusted P = 0.088). CONCLUSIONS:Among individuals ages < 65 y with calcium-to-magnesium intake ratios equal to or over 2.6, reducing the ratio to around 2.3 increased 5-methylcytosine modifications (i.e., cg16371860) and reduced 5-hydroxymethylcytosine modifications (i.e., cg26337277) in the TMPRSS2 gene. These findings, if confirmed, provide another mechanism for the role of Mg intervention in the prevention of COVID-19 and treatment of early and mild disease by modifying the phenotype of the TMPRSS2 genotype.

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn's colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000-2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4-14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation 'the colonic ectopy ileal metaplasia formation' conspicuously of pathogenic importance in CC.

BACKGROUND:The treatment, genotyping, and phenotyping of patients with World Health Organization Group 1 pulmonary arterial hypertension (PAH) have evolved dramatically in the last decade. RESEARCH QUESTION:The United States Pulmonary Hypertension Scientific Registry was established as the first US PAH patient registry to investigate genetic information, reproductive histories, and environmental exposure data in a contemporary patient population. STUDY DESIGN AND METHODS:Investigators at 15 US centers enrolled consecutively screened adults diagnosed with Group 1 PAH who had enrolled in the National Biological Sample and Data Repository for PAH (PAH Biobank) within 5 years of a cardiac catheterization demonstrating qualifying hemodynamic criteria. Exposure and reproductive histories were collected by using a structured interview and questionnaire. The biobank provided genetic data. RESULTS:, and 79% were women. Mean duration between symptom onset and diagnostic catheterization was 1.9 years. Sixty-six percent of patients were treated with more than one PAH medication at enrollment. Past use of prescription weight loss drugs (16%), recreational drugs (27%), and oral contraceptive pills (77%) was common. Women often reported miscarriage (37%), although PAH was rarely diagnosed within 6 months of pregnancy (1.9%). Results of genetic testing identified pathogenic or suspected pathogenic variants in 13% of patients, reclassifying 18% of IPAH patients and 5% of APAH patients to heritable PAH. INTERPRETATION:Patients with Group 1 PAH remain predominately middle-aged women diagnosed with IPAH or APAH. Delays in diagnosis of PAH persist. Treatment with combinations of PAH-targeted medications is more common than in the past. Women often report pregnancy complications, as well as exposure to anorexigens, oral contraceptives, and/or recreational drugs. Results of genetic tests frequently identify unsuspected heritable PAH.

BACKGROUND:Supervised exercise training improves outcomes in patients with pulmonary arterial hypertension (PAH). The effect of an unsupervised activity intervention has not been tested. RESEARCH QUESTION:Can a text-based mobile health intervention increase step counts in patients with PAH? STUDY DESIGN AND METHODS:We performed a randomized, parallel arm, single-blind clinical trial. We randomized patients to usual care or a text message-based intervention for 12 weeks. The intervention arm received three automated text messages per day with real-time step count updates and encouraging messages rooted in behavioral change theory. Individual step targets increased by 20% every 4 weeks. The primary end point was mean week 12 step counts. Secondary end points included the 6-min walk test, quality of life, right ventricular function, and body composition. RESULTS:Among 42 randomized participants, the change in raw steps between baseline and week 12 was higher in the intervention group (1,409 steps [interquartile range, -32 to 2,220] vs -149 steps [interquartile range, -1,010 to 735]; P = .02), which persisted after adjustment for age, sex, baseline step counts, and functional class (model estimated difference, 1,250 steps; P = .03). The intervention arm took a higher average number of steps on all days between days 9 and 84 (P < .05, all days). There was no difference in week 12 six-minute walk distance. Analysis of secondary end points suggested improvements in the emPHasis-10 score (adjusted change, -4.2; P = .046), a reduction in visceral fat volume (adjusted change, -170 mL; P = .023), and nearly significant improvement in tricuspid annular plane systolic excursion (model estimated difference, 1.2 mm; P = .051). INTERPRETATION:This study demonstrated the feasibility of an automated text message-based intervention to increase physical activity in patients with PAH. Additional studies are warranted to examine the effect of the intervention on clinical outcomes. CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov; No. NCT03069716; URL: www.clinicaltrials.gov.

Dipeptidyl peptidase-4 (DPP-4) inhibitors increase endogenous glucagon-like peptide-1 (GLP-1). We hypothesized that genetic variation in the gene encoding the GLP-1 receptor (GLP1R) could affect the metabolic response to DPP-4 inhibition. To evaluate the relationship between the GLP1R rs6923761 variant (G-to-A nucleic acid substitution) and metabolic responses, we performed mixed meal studies in individuals with type 2 diabetes mellitus and hypertension after 7-day treatment with placebo and the DPP-4 inhibitor sitagliptin. This analysis is a substudy of NCT02130687. The genotype frequency was 13:12:7 GG:GA:AA among individuals of European ancestry. Postprandial glucose excursion was significantly decreased in individuals carrying the rs6923761 variant (GA or AA) as compared with GG individuals during both placebo (P = 0.001) and sitagliptin treatment (P = 0.045), while intact GLP-1 levels were similar among the genotype groups. In contrast, sitagliptin lowered postprandial glucose to a greater degree in GG as compared with GA/AA individuals (P = 0.035). The relationship between GLP1R rs6923761 genotype and therapies that modulate GLP-1 signalling merits study in large populations.

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