Patricia C. Chulada

Prostaglandin synthase 1 gene disruption in mice reduces arachidonic acid-induced inflammation and indomethacin-induced gastric ulceration

Cyclooxygenases 1 and 2 (COX-1 and COX-2) are key enzymes in prostaglandin biosynthesis and the target enzymes for the widely used nonsteroidal anti-inflammatory drugs. To study the physiological roles of the individual isoforms, we have disrupted the mouse Ptgs1 gene encoding COX-1. Homozygous Ptgs1 mutant mice survive well, have no gastric pathology, and show less indomethacin-induced gastric ulceration than wild-type mice, even though their gastric prostaglandin E2 levels are about 1% of wild type. The homozygous mutant mice have reduced platelet aggregation and a decreased inflammatory response to arachidonic acid, but not to tetradecanoyl phorbol acetate. Ptgs1 homozygous mutant females mated to homozygous mutant males produce few live offspring. COX-1-deficient mice provide a useful model to distinguish the physiological roles of COX-1 and COX-2.

Allergic lung responses are increased in prostaglandin H synthase–deficient mice

To investigate the function of prostaglandin H synthase-1 and synthase-2 (PGHS-1 and PGHS-2) in the normal lung and in allergic lung responses, we examined allergen-induced pulmonary inflammation and airway hyperresponsiveness in wild-type mice and in PGHS-1(-/-) and PGHS-2(-/-) mice. Among nonimmunized saline-exposed groups, we found no significant differences in lung function or histopathology, although PGE(2) was dramatically reduced in bronchoalveolar lavage (BAL) fluid from PGHS-1(-/-) mice, relative to wild-type or PGHS-2(-/-) mice. After ovalbumin sensitization and challenge, lung inflammatory indices (BAL cells, proteins, IgE, lung histopathology) were significantly greater in PGHS-1(-/-) mice compared with PGHS-2(-/-) mice, and both were far greater than in wild-type mice, as illustrated by the ratio of eosinophils in BAL fluid (8:5:1, respectively). Both allergic PGHS-1(-/-) and PGHS-2(-/-) mice exhibited decreased baseline respiratory system compliance, whereas only allergic PGHS-1(-/-) mice showed increased baseline resistance and responsiveness to methacholine. Ovalbumin exposure caused a modest increase in lung PGHS-2 protein and a corresponding increase in BAL fluid PGE(2) in wild-type mice. We conclude that (a) PGHS-1 is the predominant enzyme that biosynthesizes PGE(2) in the normal mouse lung; (b) PGHS-1 and PGHS-2 products limit allergic lung inflammation and IgE secretion and promote normal lung function; and (c) airway inflammation can be dissociated from the development of airway hyperresponsiveness in PGHS-2(-/-) mice.

Susceptibility of cyclooxygenase-2-deficient mice to pulmonary fibrogenesis

The cyclooxygenase (COX)-2 enzyme has been implicated as an important mediator of pulmonary fibrosis. In this study, the lung fibrotic responses were investigated in COX-1 or COX-2-deficient (-/-) mice following vanadium pentoxide (V(2)O(5)) exposure. Lung histology was normal in saline-instilled wild-type and COX-deficient mice. COX-2(-/-), but not COX-1(-/-) or wild-type mice, exhibited severe inflammatory responses by 3 days following V(2)O(5) exposure and developed pulmonary fibrosis 2 weeks post-V(2)O(5) exposure. Western blot analysis and immunohistochemistry showed that COX-1 protein was present in type 2 epithelial cells, bronchial epithelial cells, and airway smooth muscle cells of saline or V(2)O(5)-exposed wild-type and COX-2(-/-) mice. COX-2 protein was present in Clara cells of wild-type and COX-1(-/-) terminal bronchioles and was strongly induced 24 hours after V(2)O(5) exposure. Prostaglandin (PG) E(2) levels in the bronchoalveolar lavage (BAL) fluid from wild-type and COX-1(-/-) mice were significantly up-regulated by V(2)O(5) exposure within 24 hours, whereas PGE(2) was not up-regulated in COX-2(-/-) BAL fluid. Tumor necrosis factor-alpha was elevated in the BAL fluid from all genotypes after V(2)O(5) exposure, but was significantly and chronically elevated in the BAL fluid from COX-2(-/-) mice above wild-type or COX-1(-/-) mice. These findings indicate that the COX-2 enzyme is protective against pulmonary fibrogenesis, and we suggest that COX-2 generation of PGE(2) is an important factor in resolving inflammation.

Implementation of evidence-based asthma interventions in post-Katrina New Orleans: the Head-off Environmental Asthma in Louisiana (HEAL) study.

Background: Childhood asthma morbidity and mortality in New Orleans, Louisiana, is among the highest in the nation. In August 2005, Hurricane Katrina created an environmental disaster that led to high levels of mold and other allergens and disrupted health care for children with asthma. Objectives: We implemented a unique hybrid asthma counselor and environmental intervention based on successful National Institutes of Health asthma interventions from the National Cooperative Inner City Asthma (NCICAS) and Inner-City Asthma (ICAS) Studies with the goal of reducing asthma symptoms in New Orleans children after Hurricane Katrina. Methods: Children (4–12 years old) with moderate-to-severe asthma (n = 182) received asthma counseling and environmental intervention for approximately 1 year. HEAL was evaluated employing several analytical approaches including a pre–post evaluation of symptom changes over the entire year, an analysis of symptoms according to the timing of asthma counselor contact, and a comparison to previous evidence-based interventions. Results: Asthma symptoms during the previous 2 weeks decreased from 6.5 days at enrollment to 3.6 days at the 12-month symptom assessment (a 45% reduction, p < 0.001), consistent with changes observed after NCICAS and ICAS interventions (35% and 62% reductions in symptom days, respectively). Children whose families had contact with a HEAL asthma counselor by 6 months showed a 4.09-day decrease [95% confidence interval (CI): 3.25 to 4.94-day decrease] in symptom days, compared with a 1.79-day decrease (95% CI: 0.90, 2.67) among those who had not yet seen an asthma counselor (p < 0.001). Conclusions: The novel combination of evidence-based asthma interventions was associated with improved asthma symptoms among children in post-Katrina New Orleans. Post-intervention changes in symptoms were consistent with previous randomized trials of NCICAS and ICAS interventions.

Indoor environmental exposures for children with asthma enrolled in the HEAL study, post-Katrina New Orleans.

Background: Rain and flooding from Hurricane Katrina resulted in widespread growth of mold and bacteria and production of allergens in New Orleans, Louisiana, which may have led to increased exposures and morbidity in children with asthma. Objectives: The goal of the Head-off Environmental Asthma in Louisiana (HEAL) study was to characterize post-Katrina exposures to mold and allergens in children with asthma. Methods: The homes of 182 children with asthma in New Orleans and surrounding parishes were evaluated by visual inspection, temperature and moisture measurements, and air and dust sampling. Air was collected using vacuum-pump spore traps and analyzed for > 30 mold taxa using bright field microscopy. Dust was collected from the children’s beds and bedroom floors and analyzed for mouse (Mus m 1), dust mite (Der p 1), cockroach (Bla g 1), and mold (Alternaria mix) allergens using ELISA. Results: More than half (62%) of the children were living in homes that had been damaged by rain, flooding, or both. Geometric mean indoor and outdoor airborne mold levels were 501 and 3,958 spores/m3, respectively. Alternaria antigen was detected in dust from 98% of homes, with 58% having concentrations > 10 µg/g. Mus m 1, Der p 1, and Bla g 1 were detected in 60%, 35%, and 20% of homes, respectively, at low mean concentrations. Conclusions: Except for Alternaria antigen in dust, concentrations of airborne mold (ratio of indoor to outdoor mold) and dust allergens in the homes of HEAL children were lower than measurements found in other studies, possibly because of extensive post-Katrina mold remediation and renovations, or because children moved into cleaner homes upon returning to New Orleans.

The Head-off Environmental Asthma in Louisiana (HEAL) Study—Methods and Study Population

Background: In the city of New Orleans, Louisiana, and surrounding parishes (NOLA), children with asthma were perilously impacted by Hurricane Katrina as a result of disrupted health care, high home mold and allergen levels, and high stress. Objectives: The Head-off Environmental Asthma in Louisiana (HEAL) study was conducted to examine relationships between the post-Katrina environment and childhood asthma in NOLA and assess a novel asthma counselor intervention that provided case management and guidance for reducing home mold and allergen levels. Methods: Children (4–12 years old) with moderate-to-severe asthma were recruited from NOLA schools. Over 1 year, they received two clinical evaluations, three home environmental evaluations, and the asthma intervention. Quarterly end points included symptom days, medication use, and unscheduled emergency department or clinic visits. A community advisory group was assembled and informed HEAL at all phases. Results: Of the children (n = 182) enrolled in HEAL, 67% were African American, and 25% came from households with annual incomes <

The Environmental Polymorphisms Registry: a DNA resource to study genetic susceptibility loci.

15,000. HEAL children were symptomatic, averaging 6.6 symptom days in the 2 weeks before baseline, and had frequent unscheduled visits to clinics or emergency departments (76% had at least one unscheduled visit in the preceding 3 months). In this report, we describe study design and baseline characteristics of HEAL children. Conclusions: Despite numerous challenges faced by investigators, study staff, and participants, including destroyed infrastructure, disrupted lives, and lost jobs, HEAL was successful in terms of recruitment and retention, the high quality of data collected that will provide insight into asthma-allergen relationships, and the asthma intervention. This success was attributable to using an adaptive approach and refining processes as needed.

The Environmental Polymorphism Registry: a unique resource that facilitates translational research of environmental disease.

The National Institute of Environmental Health Sciences is establishing a DNA repository named the Environmental Polymorphisms Registry (EPR). The goal is to recruit 20,000 subjects from the greater Research Triangle Park region of North Carolina and collect a sample of each subject’s DNA for genetic study. Personal information is obtained from each EPR subject and linked to their sample in coded form. Once individuals with the genotypes of interest are identified, their samples are decoded, and their names and contact information are given to scientists for follow-up studies in which genotype is important. “Recruit-by-genotype” resources such as the EPR require a transparent consent process and rigorous human subjects protection measures. Unlike the EPR, most US DNA resources are anonymous. Once scientists identify potentially significant genetic variants, they must screen new populations to find individuals with the variants of interest to study. The EPR eliminates this time consuming and expensive step. In designing the EPR, consideration was given to achieving high response rates, minimizing attrition and maximizing usefulness for future research studies. Subjects are recruited from outpatient clinics in area medical centers as well as from the general population to ascertain individuals in diverse states of health. Data are collected on race, ethnicity, gender and age, and are monitored for demographic diversity. As of November 2007, 7,788 individuals have been recruited into the EPR and their DNA samples have been used in numerous genetic studies. EPR subjects have also been solicited for several follow-up studies with high response rates (>90%). The success of the EPR based on the number of subjects recruited and genetic studies underway, suggests that it will be a model for future DNA resources.

The Feasibility of Creating a Population-based National Twin Registry in the United States

Background: Dissecting complex disease has become more feasible because of the availability of large-scale DNA resources and advances in high-throughput genomic technology. Although these tools help scientists identify potential susceptibility loci, subjects with relevant genotypes are needed for clinical phenotyping and toxicity studies. Objective: We have developed a resource of subjects and their DNA to use for translational research of environmental disease. Methods: More than 15,000 individuals of diverse sex, age, race, and ethnicity were recruited from North Carolina. DNA was isolated from their blood and coded with personal identification numbers linked to their identities. This linked resource of subjects and their DNA—the Environmental Polymorphism Registry (EPR)—allows scientists to screen for individuals with genotypes of interest and invite them to participate in follow-up studies. Discussion: The EPR is a phenotype-by-genotype resource designed to facilitate translational studies of environmental disease. Based on their genotypes, subjects are invited to participate at all levels of research, from basic laboratory ex vivo cell phenotyping experiments that require viable tissue to in vivo observational studies and clinical trials. Here we report on progress of the EPR since 2008. We also describe a major effort at the National Institute of Environmental Health Sciences (NIEHS) to investigate susceptibility loci in 87 environmental response genes and gene × environment interactions using EPR resources. Conclusion: The EPR is a unique and novel resource and is ideal for genotype-driven translational research of environmental disease. We expect that it will serve as a model for future resources. Such tools help scientists attain their ultimate goals: to identify at-risk populations and develop strategies for preventing and treating human disease.

Genetic Disruption of Ptgs-1, as well as of Ptgs-2, Reduces Intestinal Tumorigenesis in Min Mice

Between 4 to 6 million twins exist in the US today who offer scientists a valuable potential resource for conducting behavioral and biomedical research. However, unlike many other countries, there is no national system in the US for identifying twins and eliciting their participation in these important research programs. Therefore, the National Institute of Environmental Health Sciences (NIEHS) is conducting a study to determine the feasibility of creating a national, population-based twin registry in the US. The major goal is to estimate the potential size and characteristics of a national twin registry based on the current twin population in the US, our ability to ascertain and enroll them, and their willingness to participate. Existing US twin cohorts are also being examined in this study as well as alternatives for improving US twin resources should a national twin registry be deemed infeasible. The various options will be compared in terms of possible source populations, generalizability and adequacy for statistically powering various types of etiological studies. Two expert advisory panels have been assembled to assist in the conduct of this study. The Scientific Advisory Panel is charged with providing expertise concerning study goals, design and methodology, and evaluating the studys conclusion. A separate Ethics Advisory Panel is charged with providing expertise on the ethical, legal, and social issues that might be encountered if a national twin registry is ultimately pursued. Having a national population-based twin registry in the US would be advantageous to US scientists and those worldwide. It would provide ample numbers of twin pairs to conduct various types of environmental genomic studies currently not possible with existing US twin resources. It would also allow US scientists to select for characteristics (race, ethnicity, environments, and so on) inherent in our own population. Finally and foremost, it would help to meet the worldwide demand for twin resources which is expected to increase over time, as new genomic and analytical tools become available and new hypotheses emerge concerning the complex interplay between genes, lifestyles and environment.