https://scholarworks.korea.ac.kr/kumedicine/handle/2020.sw.kumedicine/426 2026-04-04T06:32:45Z https://scholarworks.korea.ac.kr/kumedicine/handle/2021.sw.kumedicine/79547 Title: Immune-Modulatory Effects of Micrococcus yunnanensis, a Dominant Indoor Air Bacterium in Seoul Metropolitan City Authors: Yoo, Young; Kang, Changmin; Park, Yongsung; Han, Changhak; Chong, Chanhee; Kim, Hyunseo; Yoon, Wonsuck; Song, Dae Jin Abstract: Rationale Humans inhale approximately 20–50 m^3 of air daily, establishing direct link between air quality and respiratory health. Airborne microorganisms have increasingly drawn scientific attention due to their potential impact to modulate immune responses within the respiratory tract. We hypothesized that the composition and biological activity of indoor airborne microorganisms significantly influence human respiratory immunity, particularly through dominant microbial taxa. Methods Indoor air samples from 272 diverse sites across Seoul including public facilities, transportation hubs, and residential environments. Airborne bacteria were captured via direct impaction, cultured, and taxonomically identified by 16S rDNA sequencing. Remarkably, Micrococcus yunnanensis (M. unnanensis) was ubiquitously abundant across all sampled locations. BALB/c mice which were sensitized and challenged with ovalbumin received intranasal M. yunnanensis (10^5 CFU) for examining immunomodulatory effects. Airway hyperresponsiveness (AHR) was evaluated via methacholine challenge. Cytokines, including IL-2, IL-4, IL-12, MDC, and IFN-γ in BALF and serum total IgE levels were measured. Results Exposure to M. yunnanensis significantly attenuated AHR compared to the OVA- controls. BALF concentrations of Th2 associated cytokines such as IL-4 and IL-2 were reduced, whereas Th1 cytokines, IFN-γ and IL-12 were elevated. Notably, MDC expression increased despite reduced IL-4, suggesting IgE regulation mechanisms beyond classical Th2 pathways. Conclusions These findings demonstrate that M. yunnanensis, a prevalent urban indoor bacterium, modulates respiratory immune responses by promoting Th1-skewed immunity and suppressing Th2-driven inflammation. This study highlights the potential protective role of indoor commensal microbes in allergic airway diseases and underscore the necessity of reevaluating the immunological impact of indoor microbial exposure on respiratory health. 2026-03-01T00:00:00Z https://scholarworks.korea.ac.kr/kumedicine/handle/2021.sw.kumedicine/79142 Title: Sequential Mediation by Maternal Weight Gain and Late Blood Metal Concentration in the Association Between Heavy Metal Exposure in Early Pregnancy and Fetal Growth Authors: Choe, Seung-Ah; Lee, Jue Seong; Kang, Changmin; Jo, Jungheum; Yoon, Wonsuck; Song, Dae Jin; Yoo, Young Abstract: Background: To assess the mediation effect of gestational weight gain (GWG) and blood heavy metal levels in the late pregnancy affecting the association between early pregnancy metal exposure and fetal growth. Methods: We analyzed data from Korean Children's Environmental Health Study cohort comprising 4,712 full-term births. Blood levels of lead (Pb), mercury (Hg), and cadmium (Cd) during pregnancy, and newborn birthweights were retrieved. We applied single-exposure model to assess the association between heavy metal levels and newborn anthropometric measures and conducted path analyses to examine the direct and indirect effects of heavy metal levels in early pregnancy on newborn measures. Results: Exposure to Pb ((3 = -15.470, P = 0.036) and Cd ((3 = -24.150, P = 0.004) during late pregnancy were associated with lower birthweight. Early exposure to Pb was not directly associated with lower birthweight, however, mediation of late exposure to Pb ((3 = -7.417, P = 0.049) resulted in lower birthweight ((3 = -14.787, P = 0.036). Early exposure to Hg was associated with higher birthweight, however, indirect paths via GWG ((3 = 3.626, P = 0.048) and late Hg levels ((3 = -12.929, P = 0.111) countered each other, resulting in the nullification of the total effect ((3 = -8.519, P = 0.301). Conclusion: The effect of Pb exposure in early pregnancy on birthweight was mediated by GWG and Pb exposures during late pregnancy. When assessing the impact of heavy metal exposure on birthweight, it is important to note that GWG and late heavy metal levels act as mediators, rather than confounders. 2026-01-01T00:00:00Z https://scholarworks.korea.ac.kr/kumedicine/handle/2021.sw.kumedicine/79562 Title: Cohort profile: Korean Varicella Immunization Monitoring (K-VIM) Scheme: a national cohort of children born 2011-2022 Authors: Shim, Young Kyu; Lee, Young Hwa; Choe, Young June; Yoon, Yoonsun; Kim, Yun-Kyung Abstract: Varicella, caused by the varicella-zoster virus, was once nearly universal in childhood before the advent of vaccination and may lead to severe complications and even fatalities. Monitoring varicella vaccine effectiveness is crucial yet often overlooked in settings with limited surveillance infrastructure. The Korean Varicella Immunization Monitoring (K-VIM) Scheme was established to address this gap by assembling a national, insurance-based birth cohort of children born between 2011 and 2022 (n = 4,505,165). This cohort leverages comprehensive healthcare databases in Korea to capture vaccination records, medical visits, and varicella infection outcomes for virtually all children within the target birth years. We describe the enrollment and key characteristics of the K-VIM cohort, including vaccination coverage, demographic features, and varicella incidence to date. The structure and completeness of Korea's national health insurance and immunization registries enable robust longitudinal tracking of varicella infections among vaccinated versus unvaccinated children. Early findings demonstrate distinct patterns in infection rates and disease severity according to vaccination status. The K-VIM Scheme provides a foundation for ongoing epidemiological studies of varicella vaccine effectiveness and public health impact in Korea. Future plans include evaluating the long-term effects of varicella vaccination, including potential impacts on herpes zoster incidence, using diverse study designs to strengthen causal inference and inform immunization policy. 2026-01-01T00:00:00Z https://scholarworks.korea.ac.kr/kumedicine/handle/2021.sw.kumedicine/78592 Title: Associations of pre- and postnatal levels of three heavy metals with visual impairment in 3-year-old children Authors: Ham, Dajeong; Kim, Sung-yeon; Bae, Sanghyuk; Kim, Suejin; Park, Choonghee; Song, Sanghwan; Lee, Jueun; Park, Huibyeol; Jo, Jung-heum; Jung, A-ra; Yu, Seung-do; Kim, Hyun-jeong; Jung, Soonwon; Hong, Sooyeon; Seo, Heung Won; Hwang, Namkyoung; Kang, Tackshin; Jeong, Dong-jin; Lee, Seungjune; Ha, Eun Hee; Kim, Yi-jun; Shah, Surabhi; Oh, Jongmin; Kim, Hwan-cheol; Jeong, Kyoung-sook; Kim, Byungmi; Lee, Seulbi; Kim, Hyesook; Kook, Hoon; Baek, Hee-jo; Moon, Jai-dong; Park, Wonju; Shin, Myung-geun; Ha, Mina; Paik, Ki-chung; Kwon, Ho-jang; Lim, Myung-ho; Yoo, Seung-jin; Bae, Sanghyuk; Kim, Jin-kyung; Bae, Jisuk; Hong, Young-seoub; Kim, Yu-mi; Son, Hyunjin; Park, Mi-hye; Lim, Daehyun; Kim, Jeong-hee; Hong, Sung-chul; Lee, Keun-hwa; Kim, Su-young; Kim, Woo-jin; Na, Sunghun; Lim, Myoung-nam; Yoo, Young; Song, Daejin; Lee, Jue Seong; Yoon, Wonsuck; Choe, Seung-ah; Kim, Seunghyun; Choung, Jitae; Kim, Sukyung; Kim, Jihyun; Ahn, Kangmo; Hong, Yun-chul; Choi, Baekyong; Ryoo, Seung-woo; Son, Seok-yoon; Lee, Ji-hyeon; Lee, Dongwook; Woo, Kuckhyeun; Yoon, Seongyong; Hur, Jongil; Choi, Kyung-hwa; Park, Myungsook; Lee, Seung-hwa; Chu, Yeonhee; Kim, Jung-ah; Kim, Yangho; Lee, Jiho; Sim, Chang-sun; Kim, A-ram; Oh, Inbo; Ko-CHENS Study group Abstract: Visual impairment is an important public health issue affecting young children. Environmental heavy metals, such as lead (Pb), mercury (Hg), and cadmium (Cd), are neurotoxicants that may disrupt visual development, yet evidence of their impact remains limited. We aimed to investigate the associations between pre- and postnatal blood concentrations of Pb, Hg, and Cd and the risk of visual impairment in children at age three, considering exposure timing, sex differences, and behavioral factors. We analyzed data from 599 children enrolled in the Korean Children's Environmental Health Study, a prospective cohort initially comprising 5458 children. Maternal blood metal concentrations were measured during early (<20 weeks) and late pregnancy (>30 weeks), while child blood levels were measured at 24 and 36 months. Visual impairment was defined as visual acuity (VA) below 0.5 (Snellen ≤20/40) on Jin's vision chart at age three. Logistic regression and generalized estimating equations were used to estimate associations, adjusting for confounders. Higher maternal blood Cd concentrations during early pregnancy were significantly associated with increased risk of unilateral visual impairment in offspring (OR = 2.49; 95 % CI: 2.01–3.10 per 1 μg/L). Associations were stronger among girls and children with higher screen time and lower outdoor activity. No significant differences were observed for Pb or Hg, or across other exposure time points. Our findings suggest maternal exposure to Cd during early pregnancy may adversely affect visual development in preschool children, particularly in girls and children with sedentary behaviors. Prenatal biomonitoring and targeted behavioral interventions are warranted to mitigate these risks. © 2025 Elsevier B.V., All rights reserved. 2025-12-01T00:00:00Z