Association Between Short-term Exposure To Fine Particulate Matter,the Expression Of Long Non-coding RNA And Inflammation Indicators

Background and objectiveIn recent years,the pollution of fog and haze has occurred frequently in China,resulting in serious harms to social development and people’s health.PM2.5 is main cause of the pollution of fog and haze and has attracted increasing attention of the public.PM_2.5 has a large specific surface area and can carry abundant toxic and harmful substances.Moreover,PM_2.5 has a small particle size and can penetrate deep into the lung and blood circulation,thus causing damages to human body’s many tissues and organs.Researches have demonstrated that it is related to the occurrence and development of many diseases,such as respiratory system diseases,cardiovascular system diseases,tumors,and diabetes.Inflammatory response is one of the important biological mechanisms by which PM_2.5 induces health damages.At present,the molecular regulatory mechanism of inflammatory response induced by PM2.5 has not been fully elucidated.Many researches suggest that long non-coding RNA（lncRNA）can be a key regulator of inflammatory response,and its abnormal expression may play an important role in the occurrence and development of a variety of inflammatory diseases.It was indicated by in vitro and in vivo studys that PM_2.5 exposure can affect the expression of certain lncRNAs,and the abnormal expression of lncRNAs were related to the inflammatory response induced by PM_2.5.However,there was no population-based study about the effect of PM_2.5 exposure on lncRNA expression and PM_2.5 exposure related lncRNA’s association with inflammation.We carried out a population study to evaluate the effect of short-term exposure to PM_2.5 on inflammatory response by monitoring the concentrations of ambient PM_2.5,assessing every study object’s PM_2.5 exposure level and detecting the level of inflammation indicators in the blood.In addition,we detected the expression level of lncRNA in plasma and analyzed the influence of short-term exposure to PM_2.5 on the expression of lncRNA as well as association between PM_2.5-related lncRNAs and inflammation indicators.The possibility of lncRNA as a biomarker of short-term exposure to PM_2.5 and the association between PM_2.5 exposure related lncRNA and inflammation response were explored.MethodsTwo hundred and sixty-nine community residents from Shijiazhuang City,Hebei Province were recruited as the research objects in March and April,2018.Questionnaire survey and blood collection were conducted for all objects.Short-term exposure level of PM_2.5 for each participant was estimated by the inverse distance weighted（IDW）interpolation method,based on hourly pollution concentration data from eight air quality monitoring stations in Shijiazhuang city released by China National Environmental Monitoring Center and individual’s residential address.Considering that there was a time lag between particulate exposure and its health effects,the exposure time of this study included single-day lag time and cumulative lag time.Lag0,lag1,lag2,lag3 and lag4 were included in the single-day lag time,which indicated the day of blood draw,the previous 1-,2-,3-and 4-day,respectively.Lag0-1,lag0-2,lag0-3 and lag0-4 were included in the cumulative lag time,for example,lag0-1 referred to moving average of the day of blood draw and the previous1 day,and so on.The level of IL-6,IL-8,TNF-αand CC16 in plasma were measured by ELISA.Multiple linear regression models were used to analyze the associations between per interquartile range increase in PM_2.5 exposure concentration and IL-6,IL-8,TNF-αas well as CC16.All participants were divided into low exposure group（lower than median）and high exposure group（greater than or equal to median）according to the median of PM_2.5 exposure concentration at the cumulative lag time lag0-3.Four individuals were selected in each group,and their plasma was mixed in equal volume to detect the lncRNA expression profile.The lncRNAs with expression difference between the two groups was preliminarily screened by gene microarray and qRT-PCR was used to detect relative expression levels of these lncRNAs（lnc-PRICKLE1-4:1,lnc-GPR39-7:2,lnc-TMEM167B-3:1,lnc-MTRNR2L12-3:6,lnc-FLRT2-11:2,lnc-C2orf42-6:1,and lnc-ACAD11-1:1,etc.）in plasma.Multiple linear regression models were used to analyze association between PM_2.5 exposure level at different lag time and the expression level of lncRNAs with expression difference between the two groups,as well as association between PM_2.5exposure-related lncRNAs and inflammation indicators.Results1.Association between short-term exposure to fine particulate matter and inflammation indicators in plasmaPM_2.5’s exposure level was correlated with the level of IL-6,TNF-αand CC16 in plasma.Increased IL-6 was significantly associated with exposure to PM2.5 at lag time of lag0,lag0-1,lag0-2,lag0-3 and lag0-4.The strongest association was observed for PM_2.5 exposure at lag0-4,and each interquartile range（21.74μg/m³）increase of PM_2.5exposure was associated with 19.13%（95%CI:3.36,37.44）increase in IL-6.Increased TNF-αwas significantly associated with exposure to PM_2.5 at lag time of lag0,lag0-2and lag0-3.The strongest association was observed for PM_2.5 exposure at lag0-3,and each interquartile range（24.16μg/m³）increase of PM_2.5 exposure was associated with17.12%（95%CI:6.50,28.79）increase in TNF-α.Decreased CC16 was significantly associated with exposure to PM_2.5 at lag time of lag0-3 and lag0-4.The strongest association was observed for PM_2.5 exposure at lag0-4,and each interquartile range（21.74μg/m³）increase of PM_2.5 exposure was associated with 10.15%（95%CI:1.19,18.37）decrease in CC16.2.Association between short-term exposure to fine particulate matter and the expression level of lncRNA in plasmaCompared with the low exposure group,lncRNA’s microarray expression profile of the PM_2.5 high exposure group in plasma changed significantly,with 1,191lncRNAs high expression and 1,709 lncRNAs low expression.qRT-PCR was used to identify the difference expression of these lncRNAs,and the results suggested that lncRNA lnc-PRICKLE1-4:1,lnc-GPR39-7:2,lnc-TMEM167B-3:1 and lnc-MTRNR2L12-3:6 decreased significantly in the high exposure group,which was consistent with the result of expression profile by microarray.After adjusting for potential confounding factors（age,gender,body mass index,smoking,drinking,physical exercise and education level）,multiple linear regression analysis revealed that short-term exposure to PM_2.5 was negatively correlated with the expression level of lnc-PRICKLE1-4:1,lnc-GPR39-7:2 and lnc-MTRNR2L12-3:6 in plasma.With each interquartile range increase of PM_2.5 exposure at lag time of lag0,lag2,lag4,lag0-1,lag0-2 and lag0-3,lnc-PRICKLE1-4:1 reduced by 16.56%to 26.51%,lnc-GPR39-7:2 reduced by 18.05%to 32.16%,and lnc-MTRNR2L12-3:6 reduced by32.83%to 55.96%.The strongest association was observed for PM_2.5 exposure at lag0-2,with an average decline in the proportion of 26.51%（95%CI:14.27-36.94,P<0.001）,32.16%（95%CI:15.72-45.34,P<0.01）and 55.96%（95%CI:31.27-71.78,P<0.001）,respectively.3.Association between PM_2.5 exposure related lncRNAs and inflammation indicators in plasmaGene co-expression network analysis by Cytoscape software suggested that PM_2.5 exposure related lncRNAs lnc-PRICKLE1-4:1,lnc-GPR39-7:2 and lnc-MTRNR2L12-3:6 were correlated with multiple inflammation related mRNAs,such as IL-6,IL-1β,CCL2,IFN-G,CCR7,etc.In particular,a negative correlation between lnc-PCK1-2:1 and the key inflammatory factor IL-6 was identified.KEGG analysis suggested that these mRNAs can participate in five important inflammatory signaling pathways,including JAK-STAT,MAPK,toll like receptor（TLR）,Notch and chemokine signaling pathways.Multiple linear regression analysis indicated that each one-unit increase in expression level of lnc-MTRNR2L12-3:6 was associated with a6.76%（95%CI:1.88,11.40）decrease in IL-6,consistent with the interaction trend shown by gene co-expression network analysis.And each one-unit increase in expression level of lnc-GPR39-7:2 was associated with a 10.77%（95%CI:1.09,19.43）decrease in TNF-α.Conclusion1.The short-term exposure level of PM_2.5 was positively correlated with concentration of IL-6 and TNF-αin plasma,and negatively correlated with concentration of CC16.2.The short-term exposure level of PM_2.5 was negatively correlated with expression level of lncRNA lnc-PRICKLE1-4:1,lnc-GPR39-7:2 and lnc-MTRNR2L12-3:6.3.PM_2.5 exposure-related lncRNAs were associated with inflammation indicators.The expression level of lnc-MTRNR2L12-3:6 was negatively correlated with theconcentration of IL-6 in plasma,and the expression level of lnc-GPR39-7:2 was negatively correlated with the concentration of TNF-α.Lnc-MTRNR2L12-3:6 and lnc-GPR39-7:2 may be potential biomarkers of inflammatory response induced by ambient PM_2.5 exposure.