Publications

BACKGROUND

Genetic variants that contribute to asthma susceptibility might be present at varying frequencies in different populations, which is an important consideration and advantage for performing genetic association studies in admixed populations.

OBJECTIVE

We sought to identify asthma-associated loci in African American subjects.

METHODS

We compared local African and European ancestry estimated from dense single nucleotide polymorphism genotype data in African American adults with asthma and nonasthmatic control subjects. Allelic tests of association were performed within the candidate regions identified, correcting for local European admixture.

RESULTS

We identified a significant ancestry association peak on chromosome 6q. Allelic tests for association within this region identified a single nucleotide polymorphism (rs1361549) on 6q14.1 that was associated with asthma exclusively in African American subjects with local European admixture (odds ratio, 2.2). The risk allele is common in Europe (42% in the HapMap population of Utah residents with Northern and Western European ancestry from the Centre d'Etude du Polymorphisme Humain collection) but absent in West Africa (0% in the HapMap population of Yorubans in Ibadan, Nigeria), suggesting the allele is present in African American subjects because of recent European admixture. We replicated our findings in Puerto Rican subjects and similarly found that the signal of association is largely specific to subjects who are heterozygous for African and non-African ancestry at 6q14.1. However, we found no evidence for association in European American or Puerto Rican subjects in the absence of local African ancestry, suggesting that the association with asthma at rs1361549 is due to an environmental or genetic interaction.

CONCLUSION

We identified a novel asthma-associated locus that is relevant to admixed populations with African ancestry and highlight the importance of considering local ancestry in genetic association studies of admixed populations.

BACKGROUND

Systemic lupus erythematosus (SLE) affects 1 in 2500 Americans and is associated with significant morbidity and mortality. The recent development of SLE quality measures provides an opportunity to understand gaps in clinical care and to identify modifiable factors associated with variations in quality.

OBJECTIVE

To evaluate performance on SLE quality measures as well as differences in quality of care by demographic, socioeconomic, disease, and health system characteristics.

DESIGN AND PATIENTS

Cross-sectional analysis of data derived from the Lupus Outcomes Study, a prospective, longitudinal study of 814 individuals. Principal data collection was through annual structured telephone surveys between 2009-2010. Data on 13 SLE quality measures was collected. We used regression models to estimate demographic, socioeconomic, disease, and health system characteristics associated with performance on individual and overall quality measures.

OUTCOME MEASURES

Performance on each quality measure and overall performance on all measures for which participants were eligible (pass rate).

RESULTS

Participants were eligible for a mean of five measures (range 2-12). Performance varied from 29 % (assessment of cardiovascular risk factors) to 90 % (sun avoidance counseling). The overall pass rate was 65 % (95 % CI 64 %, 65 %). In unadjusted analyses, younger age, minority race/ethnicity, poverty, shorter disease duration, fewer physician visits, and lack of health insurance, were associated with lower pass rates. Receiving care in public sector managed care organizations was associated with higher pass rates. After adjustment, younger age, having fewer physician visits and lacking health insurance remained significantly associated with lower performance; receiving care in public sector managed care organizations remained associated with higher performance.

CONCLUSIONS

We identified a number of gaps in clinical care for SLE. Factors associated with the health care system, including presence and type of health insurance, were the primary determinants of performance on quality measures in SLE.

HIV has evolved sophisticated mechanisms to avoid restriction by intracellular innate immune defenses that otherwise serve to control acute viral infection and virus dissemination. Innate defenses are triggered when pattern recognition receptor (PRR) proteins of the host cell engage pathogen-associated molecule patterns (PAMPs) present in viral products. Interferon regulatory factor 3 (IRF3) plays a central role in PRR signaling of innate immunity to drive the expression of type I interferon (IFN) and interferon-stimulated genes (ISGs), including a variety of HIV restriction factors, that serve to limit viral replication directly and/or program adaptive immunity. Productive infection of T cells by HIV is dependent upon the targeted proteolysis of IRF3 that occurs through a virus-directed mechanism that results in suppression of innate immune defenses. However, the mechanisms by which HIV controls innate immune signaling and IRF3 function are not defined. Here, we examined the innate immune response induced by HIV strains identified through their differential control of PRR signaling. We identified viruses that, unlike typical circulating HIV strains, lack the ability to degrade IRF3. Our studies show that IRF3 regulation maps specifically to the HIV accessory protein Vpu. We define a molecular interaction between Vpu and IRF3 that redirects IRF3 to the endolysosome for proteolytic degradation, thus allowing HIV to avoid the innate antiviral immune response. Our studies reveal that Vpu is an important IRF3 regulator that supports acute HIV infection through innate immune suppression. These observations define the Vpu-IRF3 interface as a novel target for therapeutic strategies aimed at enhancing the immune response to HIV.