Zhang et al. BMC Pulm Med (2021) 21:114 https://doi.org/10.1186/s12890-021-01484-9 RESEARCH ARTICLE Open Access Household mold exposure interacts with infammation-related genetic variants on childhood asthma: a case–control study Yu Zhang1,2†, Li Hua4†, Quan‑Hua Liu4, Shu‑Yuan Chu3, Yue‑Xin Gan2, Min Wu5, Yi‑Xiao Bao4, Qian Chen2* and Jun Zhang1,2* Abstract Background: A number of studies have examined the association between mold exposure and childhood asthma. However, the conclusions were inconsistent, which might be partly attributable to the lack of consideration of gene function, especially the key genes afecting the pathogenesis of childhood asthma. Research on the interactions between genes and mold exposure on childhood asthma is still very limited. We therefore examined whether there is an interaction between infammation‑related genes and mold exposure on childhood asthma. Methods: A case–control study with 645 asthmatic children and 910 non‑asthmatic children aged 3–12 years old was conducted. Eight single nucleotide polymorphisms (SNPs) in infammation‑related genes were genotyped using MassARRAY assay. Mold exposure was defned as self‑reported visible mold on the walls. Associations between visible mold exposure, SNPs and childhood asthma were evaluated using logistic regression models. In addition, crossover analyses were used to estimate the gene‑environment interactions on childhood asthma on an additive scale. Results: After excluding children without information on visible mold exposure or SNPs, 608 asthmatic and 839 non‑asthmatic children were included in the analyses. Visible mold exposure was reported in 151 asthmatic (24.8%) and 119 non‑asthmatic children (14.2%) (aOR 2.19, 95% CI 1.62–2.97). The rs7216389 SNP in gasdermin B gene (GSDMB) increased the risk of childhood asthma with each C to T substitution in a dose‑dependent pattern (additive model, aOR 1.32, 95% CI 1.11–1.57). Children carrying the rs7216389 T allele and exposed to visible mold dramatically increased the risk of childhood asthma (aOR 3.21; 95% CI 1.77–5.99). The attributable proportion due to the interac‑ tion (AP: 0.47, 95% CI 0.03–0.90) and the relative excess risk due to the interaction (RERI: 1.49, 95% CI 0–2.99) were statistically signifcant. *Correspondence: [email protected]; [email protected]; [email protected] †Yu Zhang and Li Hua have contributed equally and are considered as co‑frst authors 1 Ministry of Education‑Shanghai Key Laboratory of Children’s Environmental Health, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2 Ministry of Education‑Shanghai Key Laboratory of Children’s Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665 Kongjiang Road, Shanghai 200092, China Full list of author information is available at the end of the article © The Author(s) 2021. 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The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Zhang et al. BMC Pulm Med (2021) 21:114 Page 2 of 11 Conclusions: In the present study, there was a signifcant additive interaction between visible mold exposure and rs7216389 SNP on childhood asthma. Future studies need to consider the gene‑environment interactions when exploring the risk factors of childhood asthma. Keywords: Mold, Additive interaction, Rs7216389, Single nucleotide polymorphisms, Childhood asthma Introduction Shanghai, located at the Yangtze River estuary in the Asthma is a common chronic airway infammatory dis- East China Sea, has a typical subtropical monsoon cli- order, characterized by hyper responsiveness, obstruc- mate. Visible mold in buildings is common and frequent tion and chronic infammation of the airway [1]. It has [17]. Te surface pathogen-associated molecular pat- emerged as a major global public health problem. In 2016, terns (PAMPs) in mold could induce distinct infamma- the Global Burden of Disease (GBD) study estimated that tory phenotypes in the lungs, and increase the risk of 339.4 million people worldwide were afected by asthma, asthma development and exacerbation [18]. Meanwhile, which has increased by 3.6% since 2006 [2]. Te asthma infammation-related genes are involved in pro- and anti- epidemic experienced by high-income countries over the infammatory efects, and could modify the pathogenesis past 30 years has now become an increasing problem in of asthma caused by mold exposure. Tus, we sought to low- and middle-income countries with the economic investigate whether there is any gene-environment inter- development and urbanization. As one of the largest action between the infammation-related gene polymor- middle-income countries, China has undergone changes phisms and visible mold exposure in childhood asthma in with an unprecedented speed of urbanization, leading to Shanghai. changes in environment and child lifestyle. Meanwhile, the prevalence of childhood asthma has been increasing Material and methods rapidly [3, 4]. Te Tird Nationwide Survey of Child- Study population and design hood Asthma in Urban Areas of China (2010) found that From June 2015 to January 2016, we conducted a the prevalence of asthma in children under 14 years had case–control study aiming to explore the risk factors increased from 2.0% in 2000 to 3.0%, and Shanghai had of childhood asthma. Te design, recruitment and the the highest rate of 7.6% [2]. characteristics of the study population have been previ- Te genetic susceptibility of asthma has been dem- ously described elsewhere [19]. Briefy, children aged 3 onstrated by numerous studies using candidate gene to 12 years with asthma were recruited in the case group associations and genome-wide associations (GWAS) from the Xinhua Hospital, Shanghai, China. Children method [5, 6]. Single nucleotide polymorphisms (SNPs) with a history of recurrent wheezing (> 2 times) were in infammation-related genes have been shown to infu- examined by a physician, including medical history, ence the development of childhood asthma. However, physical exams and tests. According to the Global Initia- the results are inconsistent and inconclusive, even for the tive for Asthma (GINA) guidelines, asthmatic children most replicated genes [7], probably due to the infuence were defned by history of recurrent wheezing, feeling of of environmental factors, which play an important role in tightness or pain in the chest, cough, and with positive the physiological pathways between genes and childhood bronchial provocation (forced expiratory volume in one asthma [8]. second (FEV1) > 200 ml after inhaling bronchodilator). Te urbanization has led people, especially children, Te control group consisted of non-asthmatic children spending most of their time in the indoor environment of the same age, from the pediatric outpatient clinic and [9]. Evidence shows that the indoor environment plays pediatric surgery clinic of the same hospital. 645 asth- a key role in the development of childhood asthma matic and 910 non-asthmatic children were recruited in [10–13]. Visible mold, a common indoor dampness phe- our study. Te study protocol was approved by the Insti- nomenon, has been found closely associated with child- tutional Review Board of the Xinhua Hospital (approval hood asthma. For example, a meta-analysis with 31,742 number: XHEC-C-2014-065), and conducted accord- children from eight European birth cohorts found that ing to the principles in the Declaration of Helsinki. Te visible mold exposure during the frst 2 years of life was informed consents were signed by all parents. positively associated with childhood asthma [14]. Two large epidemiologic studies from China showed that vis- Questionnaires ible mold on walls was signifcantly associated with phy- A face-to-face interview was conducted with the parents sician-diagnosed childhood asthma in both boys and girls of the participants. Te questionnaire included informa- [15, 16]. tion on parental demographic factors, delivery mode of Zhang et al. BMC Pulm Med (2021) 21:114 Page 3 of 11 the child, feeding habits, and indoor environment includ- above. Missing data of the covariates were included as a ing visible mold and environmental tobacco smoke (ETS) separate category in the analyses. exposure. Mold exposure was assessed by the following question “Have you ever seen visible mold on your walls, Statistical analyses ceiling, or foor in your home?”. Te diferences in demographic characteristics, envi- ronmental factors and genotype frequencies of SNPs Genotyping between the cases and controls were calculated using Oral mucosal swabs were collected at recruitment and chi-square test for categorical variables, Student’s t-test maintained at -80 ºC immediately after transportation or Wilcoxon test for continuous variables. Te Hardy– to the biobank. Genomic DNA was isolated from oral Weinberg equilibrium (HWE) of allele frequencies in the mucosal swabs using the DNA extraction kit (Shanghai control group was assessed by the goodness-of-ft chi- Lifefeng Biotechnology Co., China) according to the man- square. Odds ratios (ORs) and 95% confdence intervals ufacturer’s manual.