2023 Fiscal Year Research-status Report
Potential role of chemokine (C-C motif) ligand 18 in the development of obese asthma and Type 2 inflammation using epidemiological and experimental studies
| Project/Area Number |
23K09664
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Project Period (FY) |
2023-04-01 – 2026-03-31
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| Keywords | Asthma / Obesity / Birth cohort / adult asthma cohort / CCL18 / Immune pathways / Epidemiological studies / T2 biomarkers |
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| Outline of Annual Research Achievements |
1) Hokkaido birth cohort: An ongoing population-based cohort study that began in 2002 (n = 20,926). We have finished interviews and physical examinations of children aged 10 years (n=418) for allergic condition assessment. Parents completed the ISAAC questionnaires to assess wheeze, rhinitis, and eczema. Also, information on sociodemographic characteristics, anthropometric measures, doctor-diagnosis of asthma, and confounders from pregnancy to age 10 have been collected. We have collected biospecimens in children and measured T2 biomarkers in children, including blood eosinophils, and FeNO. We measured plasma CCL18 protein as a novel T2 biomarker at ten years of age by ELISA (R&D Systems). Because of the influence of the CCL18 genotype on CCL18 levels, we will determine CCL18 polymorphism using the TaqMan system. 2) Adult asthma cohort: We enrolled patients who were diagnosed with asthma by respiratory physicians in the Hokkaido University Hospital and 29 other affiliated hospitals and clinics. A total of 220 subjects (141 with severe asthma and 79 with mild-to-moderate asthma) underwent procedural evaluations at entry and followed each year for 6 years. We have evaluated all participants for clinical parameters, pulmonary function tests, FeNO, CT images, and biosamples. We have started data analysis to assess the effect of BMI and obesity with CCL18 in asthma patients. We found that there is a significant positive association between CCL18 and BMI in asthma patients. Also, CCL18 is associated with elevated blood eosinophils, sputum eosinophils, and FeNO as T2 biomarkers.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
1) Hokkaido Birth Cohort: Recruitment of study participants at age 10 has been completed successfully. We collected baseline characteristics of parent-child pairs without issues. Information on the allergic conditions of the children, which is the main outcome of the current study using ISAAC, was gathered with minimal missing data. All survey information has been extracted, and data input into Excel files is complete. Double checks and data cleaning have also been performed. Notably, we collected biospecimens from over 95% of the children. Given the difficulty of obtaining such samples from the general population and the initial concerns about gaining consent from parents and children, this high acceptance rate is significant. T2 biomarkers in examined children were measured with almost no missing data (only 2% of the children had missing data). The determination of CCL18 genotyping and plasma CCL18 protein levels, which are key topics of the current study among children, has been successfully performed. 2) Adult Asthma: Recruitment of participants, sample collection, pulmonary function tests, and biomarker measurements were completed as planned at the start of the project. We have begun data analysis to assess the association of obesity indices with CCL18. The examination of the association between CCL18 and T2 biomarkers has been completed, yielding promising results.
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| Strategy for Future Research Activity |
We will include experimental studies to find possible mechanism(s) of CCL18's role in the obese asthma phenotype. Our plans for the next fiscal year:
1) Hokkaido birth cohort: We will extract DNA from buffy coat samples of children at age 10 to determine genetic polymorphisms of CCL18, which could have a significant effect on circulatory CCL18 levels. We will assess such possible effects in this fiscal year. Also, we will start assessing the association of BMI and obesity with CCL18 in children. As the next step and to dig further to explore the mechanism of CCL18 in obese asthma, we will examine the association of CCL18 with T2 biomarkers in children. 2) Adult asthma cohort: According to our preliminary analysis, CCL18 is an important protein in the pathogenesis of obese asthma by enhancing T2 inflammation. We will look at the association of CCL18 with pulmonary function tests, risk of exacerbation and hospitalization with a prospective approach. We will replicate such data in an additional two cohorts in this fiscal year. As with the birth cohort, we will determine the genetic polymorphisms of CCL18 in adults as well. 3) Initiation of experimental studies: Because CCL18 is not expressed in rodents, in vivo studies are not possible for this project. We will clarify the possible upstream regulatory pathways of CCL18 using in vitro studies. We will treat THP1 cells enriched for macrophages as the main source of CCL18 in humans and treat the cells with several interleukins, adipokines, and mediators to find regulatory pathways of CCL18.
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| Causes of Carryover |
Our study is a common project between two departments. In addition, there are several projects in our ongoing cohorts and expenses for general surveys and common outcomes in various projects in the same cohort. Therefore, some parts of survey conduction, data and biospecimen collection, and T2 biomarkers measurement have been handled with other financial support in the same cohort. Also, we have measured serum CCL18 protein by our staff not asking any company. Also, our technicians are doing DNA extraction and CCL18 genotyping, not asking any external party to do it. These helped us in saving budget for the next steps, doing more sophisticated measurement and experiments in next coming years. For exploration of mechanism of the association of obesity with CCL18, and interplay of CCL18 with other biomarkers and outcomes, we are planning to measure such as SomaScan. The SomaScan Platform is a high-plex, high-throughput proteomics technology revolutionizes how researchers gain insights into protein biology and protein-protein interactions. Enables 7000 protein measurements simultaneously from a single, 55 microliter sample of serum, plasma, and various other sample types.
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