Publications

Developing technologies for efficient and scalable disruption of gene expression will provide powerful tools for studying gene function, developmental pathways, and disease mechanisms. Here, we develop clustered regularly interspaced short palindromic repeat interference (CRISPRi) to repress gene expression in human induced pluripotent stem cells (iPSCs). CRISPRi, in which a doxycycline-inducible deactivated Cas9 is fused to a KRAB repression domain, can specifically and reversibly inhibit gene expression in iPSCs and iPSC-derived cardiac progenitors, cardiomyocytes, and T lymphocytes. This gene repression system is tunable and has the potential to silence single alleles. Compared with CRISPR nuclease (CRISPRn), CRISPRi gene repression is more efficient and homogenous across cell populations. The CRISPRi system in iPSCs provides a powerful platform to perform genome-scale screens in a wide range of iPSC-derived cell types, dissect developmental pathways, and model disease.

The APOL1 high-risk genotype, present in approximately 13% of blacks in the United States, is a risk factor for kidney function decline in populations with CKD. It is unknown whether genetic screening is indicated in the general population. We evaluated the prognosis of APOL1 high-risk status in participants in the population-based Atherosclerosis Risk in Communities (ARIC) study, including associations with eGFR decline, variability in eGFR decline, and related adverse health events (AKI, ESRD, hypertension, diabetes, cardiovascular disease, pre-ESRD and total hospitalization rate, and mortality). Among 15,140 ARIC participants followed from 1987-1989 (baseline) to 2011-2013, 75.3% were white, 21.5% were black/APOL1 low-risk, and 3.2% were black/APOL1 high-risk. In a demographic-adjusted analysis, blacks had a higher risk for all assessed adverse health events; however, in analyses adjusted for comorbid conditions and socioeconomic status, blacks had a higher risk for hypertension, diabetes, and ESRD only. Among blacks, the APOL1 high-risk genotype associated only with higher risk of ESRD in a fully adjusted analysis. Black race and APOL1 high-risk status were associated with faster eGFR decline (P<0.001 for each). However, we detected substantial overlap among the groups: median (10th-90th percentile) unadjusted eGFR decline was 1.5 (1.0-2.2) ml/min per 1.73 m(2) per year for whites, 2.1 (1.4-3.1) ml/min per 1.73 m(2) per year for blacks with APOL1 low-risk status, and 2.3 (1.5-3.5) ml/min per 1.73 m(2) per year for blacks with APOL1 high-risk status. The high variability in eGFR decline among blacks with and without the APOL1 high-risk genotype suggests that population-based screening is not yet justified.

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality; however, the role of inflammatory mediators in its pathobiology remains unclear. The aim of this study was to investigate the influence of gender in COPD on lipid mediator levels.Bronchoalveolar lavage fluid (BALF) and serum were obtained from healthy never-smokers, smokers and COPD patients (Global Initiative for Chronic Obstructive Lung Disease stage I-II/A-B) (n=114). 94 lipid mediators derived from the cytochrome-P450, lipoxygenase, and cyclooxygenase pathways were analysed by liquid chromatography-mass spectrometry.Multivariate modelling identified a 9-lipid panel in BALF that classified female smokers with COPD from healthy female smokers (p=6×10(-6)). No differences were observed for the corresponding male population (p=1.0). These findings were replicated in an independent cohort with 92% accuracy (p=0.005). The strongest drivers were the cytochrome P450-derived epoxide products of linoleic acid (leukotoxins) and their corresponding soluble epoxide hydrolase (sEH)-derived products (leukotoxin-diols). These species correlated with lung function (r=0.87; p=0.0009) and mRNA levels of enzymes putatively involved in their biosynthesis (r=0.96; p=0.003). Leukotoxin levels correlated with goblet cell abundance (r=0.72; p=0.028).These findings suggest a mechanism by which goblet cell-associated cytochrome-P450 and sEH activity produce elevated leukotoxin-diol levels, which play a putative role in the clinical manifestations of COPD in a female-dominated disease sub-phenotype.

RATIONALE

Household air pollution (HAP) from solid fuel combustion is a major contributor to the global burden of disease, with considerable impact from respiratory infections in children. The impact of HAP on lung function is unknown.

OBJECTIVES

The Childhood Exposure to Respirable Particulate Matter (CRECER) prospective cohort study followed Guatemalan children who participated in the Randomised Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) trial of a chimney stove intervention to determine the effect of early childhood HAP exposure on growth of lung function.

METHODS

RESPIRE households with pregnant women or infant children were randomised to receive a chimney stove at the beginning or at the end of the 18-month trial. During CRECER, a subset of these children, as well as children from households with newly installed stoves, were followed with spirometry beginning at age 5. Biomass smoke exposure was measured using personal carbon monoxide tubes. Two-stage regression models were employed to analyse associations with lung function growth.

MEASUREMENTS AND MAIN RESULTS

Longitudinal peak expiratory flow (PEF) and FEV1 data were available for 443 and 437 children, respectively, aged 5-8 (mean follow-up 1.3 years). Decreases in PEF growth of 173 mL/min/year (95% CI -341 to -7) and FEV1 of 44 mL/year (95% CI -91 to 4) were observed with stove installation at 18 months compared with stove installation at birth in analyses adjusted for multiple covariates. No statistically significant associations were observed between personal HAP exposure and lung function.

CONCLUSIONS

A significant decrease in PEF growth and a large non-significant decrease in FEV1 growth were observed with later stove installation. Additional studies including longer follow-up and cleaner stoves or fuels are needed.

BACKGROUND

Intermittent treatment with sulfadoxine-pyrimethamine is widely recommended for the prevention of malaria in pregnant women in Africa. However, with the spread of resistance to sulfadoxine-pyrimethamine, new interventions are needed.

METHODS

We conducted a double-blind, randomized, controlled trial involving 300 human immunodeficiency virus (HIV)-uninfected pregnant adolescents or women in Uganda, where sulfadoxine-pyrimethamine resistance is widespread. We randomly assigned participants to a sulfadoxine-pyrimethamine regimen (106 participants), a three-dose dihydroartemisinin-piperaquine regimen (94 participants), or a monthly dihydroartemisinin-piperaquine regimen (100 participants). The primary outcome was the prevalence of histopathologically confirmed placental malaria.

RESULTS

The prevalence of histopathologically confirmed placental malaria was significantly higher in the sulfadoxine-pyrimethamine group (50.0%) than in the three-dose dihydroartemisinin-piperaquine group (34.1%, P=0.03) or the monthly dihydroartemisinin-piperaquine group (27.1%, P=0.001). The prevalence of a composite adverse birth outcome was lower in the monthly dihydroartemisinin-piperaquine group (9.2%) than in the sulfadoxine-pyrimethamine group (18.6%, P=0.05) or the three-dose dihydroartemisinin-piperaquine group (21.3%, P=0.02). During pregnancy, the incidence of symptomatic malaria was significantly higher in the sulfadoxine-pyrimethamine group (41 episodes over 43.0 person-years at risk) than in the three-dose dihydroartemisinin-piperaquine group (12 episodes over 38.2 person-years at risk, P=0.001) or the monthly dihydroartemisinin-piperaquine group (0 episodes over 42.3 person-years at risk, P<0.001), as was the prevalence of parasitemia (40.5% in the sulfadoxine-pyrimethamine group vs. 16.6% in the three-dose dihydroartemisinin-piperaquine group [P<0.001] and 5.2% in the monthly dihydroartemisinin-piperaquine group [P<0.001]). In each treatment group, the risk of vomiting after administration of any dose of the study agents was less than 0.4%, and there were no significant differences among the groups in the risk of adverse events.

CONCLUSIONS

The burden of malaria in pregnancy was significantly lower among adolescent girls or women who received intermittent preventive treatment with dihydroartemisinin-piperaquine than among those who received sulfadoxine-pyrimethamine, and monthly treatment with dihydroartemisinin-piperaquine was superior to three-dose dihydroartemisinin-piperaquine with regard to several outcomes. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ClinicalTrials.gov number, NCT02163447.).

OBJECTIVE

To determine if trauma exposure is associated with suicidal ideation in a nationally representative sample of older adults.

METHODS

This study included 3,277 participants 55 years and older involved in the Collaborate Psychiatric Epidemiology Surveys (2001-2003).

RESULTS

Of the 84.8% of older adults who were exposed to any trauma, 2.2% endorsed late-life suicidal ideation. Multivariable models fully adjusted for sociodemographics, post-traumatic stress disorder, major depressive disorder, and substance use revealed exposure to serious accidents/illness was associated with suicidal ideation (odds ratio: 2.55; 95% confidence interval: 1.16-5.59; Wald χ(2) = 5.47, df = 1, p = 0.019). Investigation of specific traumas within the category revealed that life-threatening illness was specifically associated with suicidal ideation in older adults (odds ratio: 2.12; 95% confidence interval: 1.34-3.36; Wald χ(2) = 10.33, df = 1, p = 0.001).

CONCLUSION

These findings highlight the need for monitoring of suicidal ideation among older adults who have been informed of a life-threatening illness diagnosis.