Helminth exposure and its association with allergies and lung function in Northern European cohorts

Bakgrunn: De siste tiårene har forekomsten av astma og allergi økt over hele verden. I land hvor parasittinfeksjoner er endemiske, er forekomsten av astma og allergi lavere enn i land med lavere forekomst av parasitter. En hypotese er at parasittinfeksjoner kan beskytte mot allergiske sykdommer. Studier som har undersøkt dette er fremdeles kontroversielle, de fleste studier er fra endemiske områder og studiene gjelder oftest barn og ikke voksne. Rundormen Ascaris lumbricoides forårsaker en av de vanligste parasittinfeksjonene på verdensbasis med om lag 800 millioner smittetilfeller årlig. I løpet av livssyklusen, passerer Ascaris lungene. I tillegg til direkte skade på vev, kan infeksjonen føre til vedvarende immunologiske forandringer. I europeiske land antar man at denne typen infeksjoner begrenses av gode sanitære forhold, men forekomsten av parasitter som helminter (rundorm) og hvordan disse påvirker astma og allergi er lite studert i høyinntektsland. Formålet med studien er å: 1) Beskrive forekomst av Ascaris og Toxocara seropositivitet og eventuell sammenheng med allergiske sykdommer i to generasjoner i Norge; 2) Undersøke sammenhengen mellom helminteksponering og lungefunksjon, astma og DNA-metylering i tre kohorter fra Nord-Europa; 3) Undersøke om humant serum med Ascaris IgG4 binder seg til Ascaris-larver, og om husstøvmidd (HDM) sensibilisering bidrar til anti-Ascaris IgE- og IgG4-responser i humant serum. Material og metode: 1) Konsentrasjon av serum IgG4 mot Ascaris spp. og Toxocara spp. ble målt med endepunkttitrering i to kohorter: Foreldre fra ECRHS III-studien født 1945-1972 (n=171), og barna til disse deltagerne født 1969-2003 (n=264) (RHINESSA- studien). Data om allergisk sykdom og symptomer og andre faktorer ble samlet inn gjennom intervju og kliniske undersøkelser, bl.a. med måling av IgE i serum og hudprikktest for allergisk sensibilisering. Multivariat logistisk regresjon ble benyttet for å analysere sammenheng mellom seropositivitet og allergiske utfall. 2) IgG-antistoffer mot Ascaris i serum ble kvantifisert med ImmunoCAP (ThermoFisher) hos 671 voksne i alderen 18-47 år (46% kvinner) fra RHINESSA sentre i Aarhus, Bergen og Tartu. Seropositivitet ble definert som IgG over 90 persentilen. Multivariat logistisk/lineær regresjon ble anvendt for å analysere sammenhengen mellom Ascaris seropositivitet og astma/lungefunksjon. Alle modeller ble justert for alder, høyde og røyking, og vektet i forhold til studiesenter. DNA-metylering ble målt med Human-MethylationEPIC-chip (Illumina, USA), som dekker 850 CpG sites. I tillegg ble IgG-antistoffer mot fem helminter målt med kommersielt tilgjengelig ELISA kits (NovaTec Immunodiagnostica, Tyskland) for deltakere fra Bergen RHINESSA. 3) ELISA med fire forskjellige Ascaris-antigener for IgG4 og IgE binding ble benyttet for å bekrefte Ascaris-eksponering, hos mannlige RHINESSA deltagere fra Bergen senter kategorisert på bakgrunn av HDM sensibilisering og Ascaris IgG4 serum positivitet. Kruskal-Wallis test og Dunns Multiple sammenligningstest ble bruk for å identifisere signifikante forskjeller (p<0.05) mellom gruppene. Fluorescensmikroskopi ble benyttet for å undersøke IgG i serum og IgE binding til Ascaris-larvene. Resultater: 1) Anti-Ascaris spp. IgG4 påvist i serum hos 29% av deltakerne fra den eldre generasjonen (foreldre) og hos 10% av deres «barn», den yngre generasjonen. Anti-Toxocara spp. IgG4 ble påvist hos 18% av foreldrene og hos 8% av barna. Hos den yngre generasjonen var Toxocara seropositivitet assosiert med å ha hatt kjæledyr før 15 års alder (odds ratio (OR) = 6.15; 95%CI = 1.37-27.5) og økende BMI (1.16 [1.06-1.25] per kg/m2). Toxocara positivitet var assosiert med piping i brystet (justert OR 2.97 [1.45- 7.76]), høysnue (4.03[1.63-9.95]), eksem (2.89 [1.08-7.76]) og sensibilisering mot katt (5.65 [1.92-16.6]) for deltakere i den yngste generasjonen, men ikke for den eldre generasjonen. Selv når kjæledyrhold ble tatt med i betraktningen endret ikke dette sammenhengen mellom Toxocara seropositivitet og allergi. Toxocara spp. Seropositivitet i foreldre-generasjonen var assosiert med høyere forekomst av allergi hos deres barn (kjønns-spesifikke mønster); det bemerkes at eksponeringen ble målt flere år etter at barna var født. 2) Av de fem helmintene som ble målt med kommersielt ELISA kit, var positivt utslag på Ascaris mest hyppig. Ascaris seropositivitet var assosiert med lav FEV1 (-247 mL [-460, -34]) og høyere odds for noen gang å ha hatt astma (aOR 5.84 [1.67, 20.37]); dette gjaldt kun for menn. Funnene endret seg ikke etter å ha tatt høyde for HDM sensibilisering, og til stede for alle studiesentre (Aarhus, Bergen og Tartu). Epigenetikk analysene viste at Ascaris eksponering var forbundet med endret DNA metylering for 23 CpG lokasjoner hos menn og tre hos kvinner. Vi identifiserte hypermetylering i MYBPC1 gener, som er involvert i regulering av luftveiskontraksjon, samt endret metylering av gener som påvirker astma patogenese, slik som CRHR1 og GRK1, og av PRSS22 genet som er assosiert med nematode infeksjon. De epigenetiske analysene understøttet dermed helmint eksponeringsmålingene i populasjonene våre, sammenheng med lungehelseutfall samt kjønnsforskjell i sammenhengene. 3) Serum IgG4 binding mot Ascaris var konsistent, selv når vi benyttet forskjellige antigener. Vi påviste IgG4 binding til Ascaris larver kun for serum med forhøyet nivå av Ascaris spesifikk IgG4 (målt med ELISA), mens sensibilisering mot husstøvmidd alene (uten Ascaris IgG4 seropositivitet) ikke førte til IgG4 eller IgE binding mot Ascaris larver. Ingen av prøvene hadde påvisbare nivåer av IgE mot Ascaris og det ble heller ikke observert spesifikk eller uspesifikk IgE binding mot larvene. Konklusjon: 1) I Norge var eksponering for parasittene Ascaris og Toxocara mindre vanlig hos yngre enn hos eldre generasjoner. Imidlertid var seropositivitet mot disse assosiert med økt risiko for allergisk sykdom og symptomer hos den yngre generasjonen, men ikke hos den eldre generasjonen. Våre funn tyder på at parasitt eksponering per i dag påvirker immunsystemet på en slik måte at det kan gi økt risiko for allergi også i høyinntektsland. 2) Ascaris eksponering var assosiert med lavere lungefunksjon og økt risiko for astma hos menn. Deltagere som var Ascaris seropositive hadde endringer i DNA-metylering, forskjellig for menn og kvinner. Dette kan tyde på at Ascaris eksponering kan føre til kjønnsspesifikke epigenetiske endringer i DNA metylering som kan påvirke lungepatologi. 3) Resultatene tyder på at sensibilisering mot husstøvmidd ikke gir IgG4 eller IgE kryss-sensibilisering mot Ascaris, men at IgG4 mot Ascaris også kan binde mot allergen fra husstøvmidd. Oppsummert er dette en indikasjon på at IgG4 mot Ascaris og HDM reflekterer Ascaris eksponering og ikke HDM sensibilisering. Implikasjoner: Resultatene fra dette PhD-prosjektet tyder på at parasitteksponering i Nord-Europa kan være en risikofaktor for astma, allergi og nedsatt lungefunksjon som har vært oversett. I et folkehelseperspektiv bør det forskes mer på kilder til og eksponeringsveier for parasitter. Vi har vist i dette prosjektet at det er viktig å undersøke hvordan parasitt eksponering påvirker lungehelse i et globalt perspektiv, det gjelder både høy- og middelinntektsland, og ikke minst lavinntektsland hvor parasittinfeksjoner er svært vanlig.Background: The prevalence of asthma and allergies have increased all over the world during the past few decades. In countries where helminth infections are endemic, the prevalence of asthma and allergies appears to be lower. Therefore, it has been hypothesized that helminth infections might confer protection against allergic diseases. Results from studies linking helminth infections and allergies are still controversial with most studies addressing allergy in children in endemic regions. The round worm, Ascaris lumbricoides, is a common helminth infection worldwide with an estimated prevalence of 800 million people. During its life cycle, Ascaris migrates through the lungs causing direct damage. The infection is also likely to cause long-term altered immune responses. Data addressing the prevalence of helminths infections and their association with allergies and asthma in Europe is scarce. High sanitary standards are believed to have broken the life cycle of many helminthiases. Objectives: 1) Describe the prevalence of Ascaris and Toxocara seropositivity and test for association with allergies in two generations in Norway. 2) Investigate the association of lung function, asthma, and DNA methylation with helminth exposure in three Northern European cohorts. 3) Explore if serum anti-Ascaris IgG4 from European cohorts binds to Ascaris larvae, and test if house dust mite (HDM) sensitization leads to anti-Ascaris IgE and IgG4 responses in humans. Materials and Methods: 1) Serum levels of IgG4 against Ascaris spp. and Toxocara spp. were established by end point titration ELISA in two cohorts: parents born 1945-1972 (n = 171) from the ECRHS III study and their offspring born 1969-2003 (n = 264) from the RHINESSA study. Serum samples were first pre-incubated on plates covered with Ascaris proteins before measuring antibody levels towards Toxocara, in order to reduce cross-reactivity with Toxocara spp. Allergic outcomes and covariates were recorded through interviews and clinical examinations including measurement of serum IgE levels and skin prick tests. Multivariate logistic regression models were used to measure the association between seropositivity and allergic outcomes. 2) Serum IgG antibodies against Ascaris were measured with ImmunoCAP (ThermoFisher) in 671 adults aged 18-47 years (46% women) from Aarhus, Bergen, and Tartu RHINESSA study centres. Seropositivity was defined as IgG above the 90th percentile. Multivariate linear and logistic regression models were used to analyse Ascaris seropositivity as associated with lung function measured via spirometry, and asthma. All models were adjusted for age, height, smoking, and clustered by study centre. DNA methylation was measured from peripheral blood using Human- MethylationEPIC (Illumina, USA) chip, which measures 850k 5′-C-phosphate-G-3′ (CpG) sites. Additionally, in the Bergen study centre, IgG antibodies against five helminths were measured with commercially available ELISA kits (NovaTec Immunodiagnostica, Germany). 3) Men from the RHINESSA Bergen study centre were divided into groups, based on their HDM sensitization and Ascaris IgG4 seropositivity. Four different Ascaris antigens were used as coating antigens for the IgG4 and IgE ELISAs to confirm Ascaris exposure. Kruskal-Wallis test followed by Dunn’s Multiple comparison test was used to identify significant differences (p<0.05) between the groups. The presence of serum IgG4 and IgE binding to the larvae was imaged using fluorescence microscopy. Results: 1) Anti-Ascaris spp. IgG4 was detected in 29% of the parent generation and in 10% of the offspring, anti-Toxocara spp. IgG4 in 18% and 8% of parents and offspring, respectively. Among offspring, Toxocara seropositivity was associated with pet keeping before age the of 15 (OR = 6.15; 95%CI = 1.37-27.5) and increasing BMI (1.16 [1.06-1.25] per kg/m2). Toxocara seropositivity was associated with wheezing (adjusted odds ratio 2.97 [1.45- 7.76]), hay fever (4.03[1.63-9.95]), eczema (2.89 [1.08- 7.76]) and sensitization towards cat allergens (5.65 [1.92-16.6]) among offspring, but was not associated with allergic outcomes among parents. Adjustment for childhood or current pet keeping did not alter associations with allergies. Parental Toxocara spp. seropositivity was associated with increased offspring allergies following a sex-specific pattern, although the exposure was measured years after the birth of the offspring. 2) Among the five helminths measured, Ascaris exposure was the most common. Ascaris seropositivity was associated with lower FEV1 (-247 mL [-460, -34]) and higher odds for ever reporting asthma (aOR 5.84 [1.67, 20.37]) among men but not women, also after further adjusting for HDM sensitization. These results were consistent across study centres. At a genome-wide level, Ascaris exposure was associated with 23 differentially methylated DNA sites in men and three in women. We identified hypermethylation of the MYBPC1 gene, which is involved with regulation of airway muscle contraction. We also identified genes linked to asthma pathogenesis such as CRHR1 and GRK1, as well as a differentially methylated region in the PRSS22 gene, previously linked to nematode infection, suggesting that we are measuring true helminth exposure. 3) Serum IgG4 levels against Ascaris were consistent using the different antigens. We detected IgG4 binding to Ascaris larvae only from sera that had raised Ascaris specific IgG4 levels measured with the ELISAs. HDM sensitization only (without concurrent Ascaris IgG4 seropositivity) did not facilitate serum IgG4 or IgE binding to Ascaris larva. Furthermore, no Ascaris specific IgE levels were detected in any of the samples, and no specific or non-specific IgE binding to larvae was detected. Conclusion: 1) Helminth exposure in Norway was less frequent in younger than older adults. However, seropositivity was associated with increased risk of allergic manifestations in the younger generation, but not among their older parents. Potential changes in response to helminth exposure may provide insights into the increase in allergy incidence in affluent countries. 2) Ascaris exposure was associated with lower lung function and increased asthma risk among men. Seropositive participants had sex- specific differences in DNA methylation compared to the unexposed, thus, suggesting that Ascaris exposure may lead to sex-specific epigenetic changes that might contribute to effects on lung pathology. 3) Our results suggest that HDM sensitization does not lead to IgG4 or IgE cross-sensitization towards Ascaris, but that anti-Ascaris IgG4 appears to also bind to HDM allergens. Thus, IgG4 against Ascaris and HDM allergens appear to reflect Ascaris exposure and not HDM sensitization. Implications: Results from this PhD project suggest that exposure to helminths might be an overlooked risk factor in the development of allergies, asthma and low lung function in Northern Europe. From a public health perspective, future research should focus on pinpointing the source of this neglected exposure. Overall, our findings identify a need to investigate the role of helminths on long-term lung health globally, including in high- and middle-income countries, as well as in low-income countries, where helminth exposure is highly prevalent.Doktorgradsavhandlin

Indoor Airborne Microbiome and Endotoxin: Meteorological Events and Occupant Characteristics Are Important Determinants

Airborne bacteria and endotoxin may affect asthma and allergies. However, there is limited understanding of the environmental determinants that influence them. This study investigated the airborne microbiomes in the homes of 1038 participants from five cities in Northern Europe: Aarhus, Bergen, Reykjavik, Tartu, and Uppsala. Airborne dust particles were sampled with electrostatic dust fall collectors (EDCs) from the participants' bedrooms. The dust washed from the EDCs' clothes was used to extract DNA and endotoxin. The DNA extracts were used for quantitative polymerase chain (qPCR) measurement and 16S rRNA gene sequencing, while endotoxin was measured using the kinetic chromogenic limulus amoebocyte lysate (LAL) assay. The results showed that households in Tartu and Aarhus had a higher bacterial load and diversity than those in Bergen and Reykjavik, possibly due to elevated concentrations of outdoor bacterial taxa associated with low precipitation and high wind speeds. Bergen-Tartu had the highest difference (ANOSIM R = 0.203) in β diversity. Multivariate regression models showed that α diversity indices and bacterial and endotoxin loads were positively associated with the occupants' age, number of occupants, cleaning frequency, presence of dogs, and age of the house. Further studies are needed to understand how meteorological factors influence the indoor bacterial community in light of climate change

Helminth exposure and its association with allergies and lung function in Northern European cohorts

Bakgrunn: De siste tiårene har forekomsten av astma og allergi økt over hele verden. I land hvor parasittinfeksjoner er endemiske, er forekomsten av astma og allergi lavere enn i land med lavere forekomst av parasitter. En hypotese er at parasittinfeksjoner kan beskytte mot allergiske sykdommer. Studier som har undersøkt dette er fremdeles kontroversielle, de fleste studier er fra endemiske områder og studiene gjelder oftest barn og ikke voksne. Rundormen Ascaris lumbricoides forårsaker en av de vanligste parasittinfeksjonene på verdensbasis med om lag 800 millioner smittetilfeller årlig. I løpet av livssyklusen, passerer Ascaris lungene. I tillegg til direkte skade på vev, kan infeksjonen føre til vedvarende immunologiske forandringer. I europeiske land antar man at denne typen infeksjoner begrenses av gode sanitære forhold, men forekomsten av parasitter som helminter (rundorm) og hvordan disse påvirker astma og allergi er lite studert i høyinntektsland. Formålet med studien er å: 1) Beskrive forekomst av Ascaris og Toxocara seropositivitet og eventuell sammenheng med allergiske sykdommer i to generasjoner i Norge; 2) Undersøke sammenhengen mellom helminteksponering og lungefunksjon, astma og DNA-metylering i tre kohorter fra Nord-Europa; 3) Undersøke om humant serum med Ascaris IgG4 binder seg til Ascaris-larver, og om husstøvmidd (HDM) sensibilisering bidrar til anti-Ascaris IgE- og IgG4-responser i humant serum. Material og metode: 1) Konsentrasjon av serum IgG4 mot Ascaris spp. og Toxocara spp. ble målt med endepunkttitrering i to kohorter: Foreldre fra ECRHS III-studien født 1945-1972 (n=171), og barna til disse deltagerne født 1969-2003 (n=264) (RHINESSA- studien). Data om allergisk sykdom og symptomer og andre faktorer ble samlet inn gjennom intervju og kliniske undersøkelser, bl.a. med måling av IgE i serum og hudprikktest for allergisk sensibilisering. Multivariat logistisk regresjon ble benyttet for å analysere sammenheng mellom seropositivitet og allergiske utfall. 2) IgG-antistoffer mot Ascaris i serum ble kvantifisert med ImmunoCAP (ThermoFisher) hos 671 voksne i alderen 18-47 år (46% kvinner) fra RHINESSA sentre i Aarhus, Bergen og Tartu. Seropositivitet ble definert som IgG over 90 persentilen. Multivariat logistisk/lineær regresjon ble anvendt for å analysere sammenhengen mellom Ascaris seropositivitet og astma/lungefunksjon. Alle modeller ble justert for alder, høyde og røyking, og vektet i forhold til studiesenter. DNA-metylering ble målt med Human-MethylationEPIC-chip (Illumina, USA), som dekker 850 CpG sites. I tillegg ble IgG-antistoffer mot fem helminter målt med kommersielt tilgjengelig ELISA kits (NovaTec Immunodiagnostica, Tyskland) for deltakere fra Bergen RHINESSA. 3) ELISA med fire forskjellige Ascaris-antigener for IgG4 og IgE binding ble benyttet for å bekrefte Ascaris-eksponering, hos mannlige RHINESSA deltagere fra Bergen senter kategorisert på bakgrunn av HDM sensibilisering og Ascaris IgG4 serum positivitet. Kruskal-Wallis test og Dunns Multiple sammenligningstest ble bruk for å identifisere signifikante forskjeller (p<0.05) mellom gruppene. Fluorescensmikroskopi ble benyttet for å undersøke IgG i serum og IgE binding til Ascaris-larvene. Resultater: 1) Anti-Ascaris spp. IgG4 påvist i serum hos 29% av deltakerne fra den eldre generasjonen (foreldre) og hos 10% av deres «barn», den yngre generasjonen. Anti-Toxocara spp. IgG4 ble påvist hos 18% av foreldrene og hos 8% av barna. Hos den yngre generasjonen var Toxocara seropositivitet assosiert med å ha hatt kjæledyr før 15 års alder (odds ratio (OR) = 6.15; 95%CI = 1.37-27.5) og økende BMI (1.16 [1.06-1.25] per kg/m2). Toxocara positivitet var assosiert med piping i brystet (justert OR 2.97 [1.45- 7.76]), høysnue (4.03[1.63-9.95]), eksem (2.89 [1.08-7.76]) og sensibilisering mot katt (5.65 [1.92-16.6]) for deltakere i den yngste generasjonen, men ikke for den eldre generasjonen. Selv når kjæledyrhold ble tatt med i betraktningen endret ikke dette sammenhengen mellom Toxocara seropositivitet og allergi. Toxocara spp. Seropositivitet i foreldre-generasjonen var assosiert med høyere forekomst av allergi hos deres barn (kjønns-spesifikke mønster); det bemerkes at eksponeringen ble målt flere år etter at barna var født. 2) Av de fem helmintene som ble målt med kommersielt ELISA kit, var positivt utslag på Ascaris mest hyppig. Ascaris seropositivitet var assosiert med lav FEV1 (-247 mL [-460, -34]) og høyere odds for noen gang å ha hatt astma (aOR 5.84 [1.67, 20.37]); dette gjaldt kun for menn. Funnene endret seg ikke etter å ha tatt høyde for HDM sensibilisering, og til stede for alle studiesentre (Aarhus, Bergen og Tartu). Epigenetikk analysene viste at Ascaris eksponering var forbundet med endret DNA metylering for 23 CpG lokasjoner hos menn og tre hos kvinner. Vi identifiserte hypermetylering i MYBPC1 gener, som er involvert i regulering av luftveiskontraksjon, samt endret metylering av gener som påvirker astma patogenese, slik som CRHR1 og GRK1, og av PRSS22 genet som er assosiert med nematode infeksjon. De epigenetiske analysene understøttet dermed helmint eksponeringsmålingene i populasjonene våre, sammenheng med lungehelseutfall samt kjønnsforskjell i sammenhengene. 3) Serum IgG4 binding mot Ascaris var konsistent, selv når vi benyttet forskjellige antigener. Vi påviste IgG4 binding til Ascaris larver kun for serum med forhøyet nivå av Ascaris spesifikk IgG4 (målt med ELISA), mens sensibilisering mot husstøvmidd alene (uten Ascaris IgG4 seropositivitet) ikke førte til IgG4 eller IgE binding mot Ascaris larver. Ingen av prøvene hadde påvisbare nivåer av IgE mot Ascaris og det ble heller ikke observert spesifikk eller uspesifikk IgE binding mot larvene. Konklusjon: 1) I Norge var eksponering for parasittene Ascaris og Toxocara mindre vanlig hos yngre enn hos eldre generasjoner. Imidlertid var seropositivitet mot disse assosiert med økt risiko for allergisk sykdom og symptomer hos den yngre generasjonen, men ikke hos den eldre generasjonen. Våre funn tyder på at parasitt eksponering per i dag påvirker immunsystemet på en slik måte at det kan gi økt risiko for allergi også i høyinntektsland. 2) Ascaris eksponering var assosiert med lavere lungefunksjon og økt risiko for astma hos menn. Deltagere som var Ascaris seropositive hadde endringer i DNA-metylering, forskjellig for menn og kvinner. Dette kan tyde på at Ascaris eksponering kan føre til kjønnsspesifikke epigenetiske endringer i DNA metylering som kan påvirke lungepatologi. 3) Resultatene tyder på at sensibilisering mot husstøvmidd ikke gir IgG4 eller IgE kryss-sensibilisering mot Ascaris, men at IgG4 mot Ascaris også kan binde mot allergen fra husstøvmidd. Oppsummert er dette en indikasjon på at IgG4 mot Ascaris og HDM reflekterer Ascaris eksponering og ikke HDM sensibilisering. Implikasjoner: Resultatene fra dette PhD-prosjektet tyder på at parasitteksponering i Nord-Europa kan være en risikofaktor for astma, allergi og nedsatt lungefunksjon som har vært oversett. I et folkehelseperspektiv bør det forskes mer på kilder til og eksponeringsveier for parasitter. Vi har vist i dette prosjektet at det er viktig å undersøke hvordan parasitt eksponering påvirker lungehelse i et globalt perspektiv, det gjelder både høy- og middelinntektsland, og ikke minst lavinntektsland hvor parasittinfeksjoner er svært vanlig

Prevalence of allergic sensitization to storage mites in Northern Europe

Background: Allergic sensitization to storage mites has mostly been related to occupational exposures like farming, grain/cattle handling, whereas for non‐occupational settings, storage mite sensitization has been attributed to cross‐reactivity with house dust mite (HDM) allergens. Objective: We aimed to describe the prevalence of allergic sensitization to storage mites, co‐sensitization to HDM allergens and respiratory symptoms in Denmark, Iceland, Norway and Sweden. Methods: The population comprised of 1180 participants born 1945‐1972 of the third follow‐up of the population‐based cohort European Community Respiratory Health Survey (ECRHS) in Aarhus, Bergen, Reykjavik and Uppsala. A clinical examination included skin prick tests (SPT) to Lepidoglyphus destructor , Tyrophagus putrescentiae , Acarus siro and common inhalant allergens, as well as standardized interviews. Results: 8% were sensitized to HDM and 10% to storage mite, with some variation by study centre: Reykjavik 13%, Bergen 8% and Aarhus 7%. In Uppsala, only L destructor (3%) was measured. Storage mite sensitization was higher among men (11%) than women (8%). Among storage mite sensitized, 44% were also sensitized to HDM. Storage mite sensitization was associated with asthma and nasal allergies, but not with age, education, pet keeping or place of upbringing. Conclusions and Clinical Relevance: In this Northern European population‐based study, allergic sensitization to storage mite was as common as HDM sensitization. Storage mite sensitization was, independently of HDM sensitization, associated with respiratory symptoms and asthma. Our findings suggest that storage mite sensitization should be evaluated with regard to inclusion into the common inhalant allergen panel in Northern Europe

Ascaris exposure and its association with lung function, asthma, and DNA methylation in Northern Europe

Background Ascaris infections, with a worldwide prevalence above 10%, can cause respiratory pathology. However, long-term effects on lung function in humans are largely unknown. Objective We investigated the associations of Ascaris exposure with lung function, asthma, and DNA methylation. Methods Serum Ascaris IgG antibodies were measured in 671 adults aged 18 to 47 years (46% women) from Aarhus, Bergen, and Tartu RHINESSA study centers. Seropositivity was defined as IgG above the 90th percentile. Linear and logistic regressions were used to analyze Ascaris seropositivity as associated with lung function and asthma, adjusted for age, height, and smoking and clustered by center. DNA methylation in blood was profiled by a commercial methylation assay. Results Ascaris seropositivity was associated with lower FEV1 (−247 mL; 95% CI, −460, −34) and higher odds for asthma (adjusted odds ratio, 5.84; 95% CI, 1.67, 20.37) among men but not women, also after further adjusting for house dust mite sensitivity, consistent across study centers. At a genome-wide level, Ascaris exposure was associated with 23 differentially methylated sites in men and 3 in women. We identified hypermethylation of the MYBPC1 gene, which can regulate airway muscle contraction. We also identified genes linked to asthma pathogenesis such as CRHR1 and GRK1, as well as a differentially methylated region in the PRSS22 gene linked to nematode infection. Conclusion Ascaris exposure was associated with substantially lower lung function and increased asthma risk among men. Seropositive participants had sex-specific differences in DNA methylation compared to the unexposed, thus suggesting that exposure may lead to sex-specific epigenetic changes associated with lung pathology

Zoonotic helminth exposure and risk of allergic diseases: A study of two generations in Norway

Background Animal and human studies indicate that definitive host helminth infections may confer protection from allergies. However, zoonotic helminths, such as Toxocara species (spp.), have been associated with increased allergies. Objective We describe the prevalence of Toxocara spp. and Ascaris spp. seropositivity and associations with allergic diseases and sensitization, in 2 generations in Bergen, Norway. Methods Serum levels of total IgG4, anti-Toxocara spp. IgG4 and Ascaris spp. IgG4 were established by ELISA in 2 cohorts: parents born 1945-1972 (n = 171) and their offspring born 1969-2003 (n = 264). Allergic outcomes and covariates were recorded through interviews and clinical examinations including serum IgEs and skin prick tests. Results Anti-Ascaris spp. IgG4 was detected in 29.2% of parents and 10.3% of offspring, and anti-Toxocara spp. IgG4 in 17.5% and 8.0% of parents and offspring, respectively. Among offspring, anti-Toxocara spp. IgG4 was associated with pet keeping before age 15 (OR = 6.15; 95% CI = 1.37-27.5) and increasing BMI (1.16[1.06-1.25] per kg/m2). Toxocara spp. seropositivity was associated with wheeze (2.97[1.45- 7.76]), hayfever (4.03[1.63-9.95]), eczema (2.89[1.08-7.76]) and cat sensitization (5.65[1.92-16.6]) among offspring, but was not associated with allergic outcomes among parents. Adjustment for childhood or current pet keeping did not alter associations with allergies. Parental Toxocara spp. seropositivity was associated with increased offspring allergies following a sex-specific pattern. Conclusions & Clinical Relevance Zoonotic helminth exposure in Norway was less frequent in offspring than parents; however, Toxocara spp. seropositivity was associated with increased risk of allergic manifestations in the offspring generation, but not among parents. Changes in response to helminth exposure may provide insights into the increase in allergy incidence in affluent countries

Parents’ smoking onset before conception as related to body mass index and fat mass in adult offspring: Findings from the RHINESSA generation study

Emerging evidence suggests that parents’ preconception exposures may influence offspring health. We aimed to investigate maternal and paternal smoking onset in specific time windows in relation to offspring body mass index (BMI) and fat mass index (FMI). We investigated fathers (n = 2111) and mothers (n = 2569) aged 39–65 years, of the population based RHINE and ECRHS studies, and their offspring aged 18–49 years (n = 6487, mean age 29.6 years) who participated in the RHINESSA study. BMI was calculated from self-reported height and weight, and FMI was estimated from bioelectrical impedance measures in a subsample. Associations with parental smoking were analysed with generalized linear regression adjusting for parental education and clustering by study centre and family. Interactions between offspring sex were analysed, as was mediation by parental pack years, parental BMI, offspring smoking and offspring birthweight. Fathers’ smoking onset before conception of the offspring (onset ≥15 years) was associated with higher BMI in the offspring when adult (β 0.551, 95%CI: 0.174–0.929, p = 0.004). Mothers’ preconception and postnatal smoking onset was associated with higher offspring BMI (onset <15 years: β1.161, 95%CI 0.378–1.944; onset ≥15 years: β0.720, 95%CI 0.293–1.147; onset after offspring birth: β2.257, 95%CI 1.220–3.294). However, mediation analysis indicated that these effects were fully mediated by parents’ postnatal pack years, and partially mediated by parents’ BMI and offspring smoking. Regarding FMI, sons of smoking fathers also had higher fat mass (onset <15 years β1.604, 95%CI 0.269–2.939; onset ≥15 years β2.590, 95%CI 0.544–4.636; and onset after birth β2.736, 95%CI 0.621–4.851). There was no association between maternal smoking and offspring fat mass. We found that parents’ smoking before conception was associated with higher BMI in offspring when they reached adulthood, but that these effects were mediated through parents’ pack years, suggesting that cumulative smoking exposure during offspring’s childhood may elicit long lasting effects on offspring BMI

Maternal preconception occupational exposure to cleaning products and disinfectants and offspring asthma

Background Emerging research suggests health effects in offspring after parental chemical exposures before conception. Many future mothers are exposed to potent chemicals at work, but potential offspring health effects are hardly investigated. Objective We sought to investigate childhood asthma in relation to mother’s occupational exposure to cleaning products and disinfectants before conception. Methods The multicenter Respiratory Health In Northern Europe/Respiratory Health In Northern Europe, Spain and Australia generation study investigated asthma and wheeze starting at age less than 10 years in 3318 mother-offspring pairs. From an asthma-specific Job-Exposure Matrix and mothers’ occupational history, we defined maternal occupational exposure to indoor cleaning agents (cleaning products/detergents and disinfectants) starting before conception, in the 2-year period around conception and pregnancy, or after birth. Never-employed mothers were excluded. Exposed groups include cleaners, health care workers, cooks, and so forth. Associations were analyzed using mixed-effects logistic regression and ordinary logistic regression with clustered robust SEs and adjustment for maternal education. Results Maternal occupational exposure to indoor cleaning starting preconception and continuing (n = 610) was associated with offspring’s childhood asthma: odds ratio 1.56 (95% CI, 1.05-2.31), childhood asthma with nasal allergies: 1.77 (1.13-2.77), and childhood wheeze and/or asthma: 1.71 (95% CI, 1.19-2.44). Exposure starting around conception and pregnancy (n = 77) was associated with increased childhood wheeze and/or asthma: 2.25 (95% CI, 1.03-4.91). Exposure starting after birth was not associated with asthma outcomes (1.13 [95% CI, 0.71-1.80], 1.15 [95% CI, 0.67-1.97], 1.08 [95% CI, 0.69-1.67]). Conclusions Mother’s occupational exposure to indoor cleaning agents starting before conception, or around conception and pregnancy, was associated with more childhood asthma and wheeze in offspring. Considering potential implications for vast numbers of women in childbearing age using cleaning agents, and their children, further research is imperative

Parental Prepuberty Overweight and Offspring Lung Function

In a recent study we found that fathers’ but not mothers’ onset of overweight in puberty was associated with asthma in adult offspring. The potential impact on offspring’s adult lung function, a key marker of general and respiratory health, has not been studied. We investigated the potential causal effects of parents’ overweight on adult offspring’s lung function within the paternal and maternal lines. We included 929 offspring (aged 18–54, 54% daughters) of 308 fathers and 388 mothers (aged 40–66). Counterfactual-based multi-group mediation analyses by offspring’s sex (potential moderator) were used, with offspring’s prepubertal overweight and/or adult height as potential mediators. Unknown confounding was addressed by simulation analyses. Fathers’ overweight before puberty had a negative indirect effect, mediated through sons’ height, on sons’ forced expiratory volume in one second (FEV1) (beta (95% CI): −144 (−272, −23) mL) and forced vital capacity (FVC) (beta (95% CI): −210 (−380, −34) mL), and a negative direct effect on sons’ FVC (beta (95% CI): −262 (−501, −9) mL); statistically significant effects on FEV1/FVC were not observed. Mothers’ overweight before puberty had neither direct nor indirect effects on offspring’s lung function. Fathers’ overweight starting before puberty appears to cause lower FEV1 and FVC in their future sons. The effects were partly mediated through sons’ adult height but not through sons’ prepubertal overweight

Indoor airborne microbiome and endotoxin : meteorological events and occupant characteristics are important determinants

Airborne bacteria and endotoxin may affect asthma and allergies. However, there is limited understanding of the environmental determinants that influence them. This study investigated the airborne microbiomes in the homes of 1038 participants from five cities in Northern Europe: Aarhus, Bergen, Reykjavik, Tartu, and Uppsala. Airborne dust particles were sampled with electrostatic dust fall collectors (EDCs) from the participants' bedrooms. The dust washed from the EDCs' clothes was used to extract DNA and endotoxin. The DNA extracts were used for quantitative polymerase chain (qPCR) measurement and 16S rRNA gene sequencing, while endotoxin was measured using the kinetic chromogenic limulus amoebocyte lysate (LAL) assay. The results showed that households in Tartu and Aarhus had a higher bacterial load and diversity than those in Bergen and Reykjavik, possibly due to elevated concentrations of outdoor bacterial taxa associated with low precipitation and high wind speeds. Bergen-Tartu had the highest difference (ANOSIM R = 0.203) in β diversity. Multivariate regression models showed that α diversity indices and bacterial and endotoxin loads were positively associated with the occupants' age, number of occupants, cleaning frequency, presence of dogs, and age of the house. Further studies are needed to understand how meteorological factors influence the indoor bacterial community in light of climate change