Genome-wide association study of preserved ratio impaired spirometry (PRISm).

BACKGROUND: Preserved ratio impaired spirometry (PRISm) is defined as a forced expiratory volume in 1 s (FEV1) <80% predicted and FEV1/forced vital capacity ≥0.70. PRISm is associated with respiratory symptoms and comorbidities. Our objective was to discover novel genetic signals for PRISm and see if they provide insight into the pathogenesis of PRISm and associated comorbidities. METHODS: We undertook a genome-wide association study (GWAS) of PRISm in UK Biobank participants (Stage 1), and selected single nucleotide polymorphisms (SNPs) reaching genome-wide significance for replication in 13 cohorts (Stage 2). A combined meta-analysis of Stage 1 and Stage 2 was done to determine top SNPs. We used cross-trait linkage disequilibrium score regression to estimate genome-wide genetic correlation between PRISm and pulmonary and extrapulmonary traits. Phenome-wide association studies of top SNPs were performed. RESULTS: 22 signals reached significance in the joint meta-analysis, including four signals novel for lung function. A strong genome-wide genetic correlation (rg) between PRISm and spirometric COPD (rg=0.62, p<0.001) was observed, and genetic correlation with type 2 diabetes (rg=0.12, p=0.007). Phenome-wide association studies showed that 18 of 22 signals were associated with diabetic traits and seven with blood pressure traits. CONCLUSION: This is the first GWAS to successfully identify SNPs associated with PRISm. Four of the signals, rs7652391 (nearest gene MECOM), rs9431040 (HLX), rs62018863 (TMEM114) and rs185937162 (HLA-B), have not been described in association with lung function before, demonstrating the utility of using different lung function phenotypes in GWAS. Genetic factors associated with PRISm are strongly correlated with risk of both other lung diseases and extrapulmonary comorbidity.

Newborn screening for primary carnitine deficiency: who will benefit? - a retrospective cohort study.

BACKGROUND: Newborn screening (NBS) programmes identify a wide range of disease phenotypes, which raises the question whether early identification and treatment is beneficial for all. This study aims to answer this question for primary carnitine deficiency (PCD) taking into account that NBS for PCD identifies newborns with PCD and also until then undiagnosed mothers. METHODS: We investigated clinical, genetic (variants in SLC22A5 gene) and functional (carnitine transport activity in fibroblasts) characteristics of all referred individuals through NBS (newborns and mothers) and clinically diagnosed patients with PCD (not through NBS). Disease phenotype in newborns was predicted using data from PCD mothers and cases published in literature with identical SLC22A5 variants. RESULTS: PCD was confirmed in 19/131 referred newborns, 37/82 referred mothers and 5 clinically diagnosed patients. Severe symptoms were observed in all clinically diagnosed patients, 1 newborn and none of the mothers identified by NBS. PCD was classified as severe in all 5 clinically diagnosed patients, 3/19 newborns and 1/37 mothers; as benign in 8/19 newborns and 36/37 mothers and as unknown in 8/19 newborns. Carnitine transport activity completely separated severe phenotype from benign phenotype (median (range): 4.0% (3.5-5.0)] vs 26% (9.5-42.5), respectively). CONCLUSION: The majority of mothers and a significant proportion of newborns with PCD identified through NBS are likely to remain asymptomatic without early treatment. Conversely, a small proportion of newborns with predicted severe PCD could greatly benefit from early treatment. Genetic variants and carnitine transport activity can be used to distinguish between these groups.

Highlights from the 11th Bronchitis International Symposium: "Heterogeneity of Lung Disease in a Changing Environment," Groningen, The Netherlands, 2024.

This meeting report provides an overview of the highlights of the Bronchitis XI international symposium, held in June 2024 in Groningen, The Netherlands. The theme of this year's symposium was "heterogeneity of lung disease in a changing environment," and the symposium contained five different sessions focused on (i) heterogeneity of chronic lung disease, (ii) environmental changes with impact on lung disease, (iii) the aging lung, (iv) bronchitis, and (v) innovative therapy. The highlights from each of these sessions will be discussed separately, providing an overview of latest studies, new data, and enthralling discussions.

FAM13A regulates cellular senescence marker p21 and mitochondrial reactive oxygen species production in airway epithelial cells.

Inhalation of noxious gasses induces oxidative stress in airway epithelial cells (AECs), which may lead to cellular senescence and contribute to the development of chronic obstructive pulmonary disease (COPD). FAM13A, a well-known COPD susceptibility gene, is highly expressed in airway epithelium. We studied whether its expression is associated with aging and cellular senescence and affects airway epithelial responses to paraquat, a cellular senescence inducer. The association between age and FAM13A expression was investigated in two datasets of human lung tissue and bronchial brushings from current/ex-smokers with/without COPD. Protein levels of FAM13A and cellular senescence marker p21 were investigated using immunohistochemistry in lung tissue from patients with COPD. In vitro, FAM13A and P21 expression was assessed using qPCR in air-liquid-interface (ALI)-differentiated AECs in absence/presence of paraquat. In addition, FAM13A was overexpressed in human bronchial epithelial 16HBE cells and the effect on P21 expression (qPCR) and mitochondrial reactive oxygen species (ROS) production (MitoSOX staining) was assessed. Lower FAM13A expression was significantly associated with increasing age in lung tissue and bronchial epithelium. In airway epithelium of patients with COPD, we found a negative correlation between FAM13A and p21 protein levels. In ALI-differentiated AECs, the paraquat-induced decrease in FAM13A expression was accompanied by increased P21 expression. In 16HBE cells, the overexpression of FAM13A significantly reduced paraquat-induced P21 expression and mitochondrial ROS production. Our data suggest that FAM13A expression decreases with aging, resulting in higher P21 expression and mitochondrial ROS production in the airway epithelium, thus facilitating cellular senescence and as such potentially contributing to accelerated lung aging in COPD.NEW & NOTEWORTHY To our knowledge, this is the first study investigating the role of the COPD susceptibility gene FAM13A in aging and cellular senescence. We found that FAM13A negatively regulates the expression of the cellular senescence marker P21 and mitochondrial ROS production in the airway epithelium. In this way, the lower expression of FAM13A observed upon aging may facilitate cellular senescence and potentially contribute to accelerated lung aging in COPD.

Age-associated differences in the human lung extracellular matrix.

Extracellular matrix (ECM) remodeling has been associated with chronic lung diseases. However, information about specific age-associated differences in lung ECM is currently limited. In this study, we aimed to identify and localize age-associated ECM differences in human lungs using comprehensive transcriptomic, proteomic, and immunohistochemical analyses. Our previously identified age-associated gene expression signature of the lung was re-analyzed limiting it to an aging signature based on 270 control patients (37-80 years) and focused on the Matrisome core geneset using geneset enrichment analysis. To validate the age-associated transcriptomic differences on protein level, we compared the age-associated ECM genes (false discovery rate, FDR < 0.05) with a profile of age-associated proteins identified from a lung tissue proteomics dataset from nine control patients (49-76 years) (FDR < 0.05). Extensive immunohistochemical analysis was used to localize and semi-quantify the age-associated ECM differences in lung tissues from 62 control patients (18-82 years). Comparative analysis of transcriptomic and proteomic data identified seven ECM proteins with higher expression with age at both gene and protein levels: COL1A1, COL6A1, COL6A2, COL14A1, FBLN2, LTBP4, and LUM. With immunohistochemistry, we demonstrated higher protein levels with age for COL6A2 in whole tissue, parenchyma, airway wall, and blood vessel, for COL14A1 and LUM in bronchial epithelium, and COL1A1 in lung parenchyma. Our study revealed that higher age is associated with lung ECM remodeling, with specific differences occurring in defined regions within the lung. These differences may affect lung structure and physiology with aging and as such may increase susceptibility to developing chronic lung diseases.NEW & NOTEWORTHY We identified seven age-associated extracellular matrix (ECM) proteins, i.e., COL1A1, COL6A1, COL6A2 COL14A1, FBLN2, LTBP4, and LUM with higher transcript and protein levels in human lung tissue with age. Extensive immunohistochemical analysis revealed significant age-associated differences for COL6A2 in whole tissue, parenchyma, airway wall, and vessel, for COL14A1 and LUM in bronchial epithelium, and COL1A1 in parenchyma. Our findings lay a new foundation for the investigation of ECM differences in age-associated chronic lung diseases.

Epidemiology of Pathogens Listed as Potential Bioterrorism Agents, the Netherlands, 2009‒2019.

We provide incidences (cases/10 million persons) in the Netherlands during 2009-2019 for pathogens listed as potential bioterrorism agents. We included pathogens from the highest categories of the European Medicines Agency or the US Centers for Disease Control and Prevention. Notifiable diseases and recently published data were used to calculate the average annual incidence. Coxiella burnetii had the highest incidence because of a Q fever epidemic during 2007-2010. Incidence then decreased to 10.8 cases/. Pathogens with an incidence >1 were Brucella spp. (2.5 cases), Francisella tularensis (1.3 cases), and Burkholderia pseudomallei (1.1 cases). Pathogens with an incidence <1 were hemorrhagic fever viruses (0.3 cases), Clostridium botulinum (0.2 cases), and Bacillus anthracis (0.1 cases). Variola major and Yersinia pestis were absent. The generally low incidences make it unlikely that ill-meaning persons can isolate these pathogens from natural sources in the Netherlands. However, the pathogens are stored in laboratories, underscoring the need for biosecurity measures.

Presence of Burkholderia pseudomallei in Soil, Nigeria, 2019.

Melioidosis, caused by the soil-dwelling bacterium Burkholderia pseudomallei, is predicted to be endemic in Nigeria but is only occasionally reported. This report documents the systematic identification of the presence of B. pseudomallei and B. thailandensis in the soil across multiple states in Nigeria.

Routine and interval detection of locoregional breast cancer recurrences and risk of subsequent distant metastasis.

PURPOSE: Follow-up for breast cancer survivors consists of after care and surveillance. The benefits of routine surveillance visits remain debatable. In this study we compared the severity of locoregional recurrences (LRRs) and the subsequent risk of a distant metastasis (DM) between LRRs detected at routine and interval visits. METHODS: Women diagnosed with early breast cancer between 2003 and 2008 in one of the 15 participating hospitals, and who developed a LRR as first event after primary treatment, were selected from the Netherlands Cancer Registry (Cohort A). Chi-squared tests were used to compare the severity of routine- and interval-detected local recurrences (LRs) and regional recurrences (RRs), using tumor size, tumor grade, and number of positive lymph nodes. Data on the development of a subsequent DM after a LRR were available for a subset of patients (Cohort B). Cohort B was used to estimate the association between way of LRR-detection and risk of a DM. RESULTS: Cohort A consisted of 109 routine- and 113 interval-LRR patients. The severity of routine-detected LRs or RRs and interval-detected LRs or RRs did not significantly differ. Cohort B consisted of 66 routine- and 61 interval-LRR patients. Sixteen routine- (24%) and 17 (28%) interval-LRR patients developed a DM. After adjustment, way of LRR-detection was not significantly associated with the risk of a DM (hazard ratio: 1.22; 95% confidence interval: 0.49-3.06). CONCLUSION: The current study showed that routine visits did not lead to less severe LRRs and did not decrease the risk of a subsequent DM.

Genome-wide association study of chronic sputum production implicates loci involved in mucus production and infection.

BACKGROUND: Chronic sputum production impacts on quality of life and is a feature of many respiratory diseases. Identification of the genetic variants associated with chronic sputum production in a disease agnostic sample could improve understanding of its causes and identify new molecular targets for treatment. METHODS: We conducted a genome-wide association study (GWAS) of chronic sputum production in UK Biobank. Signals meeting genome-wide significance (p<5×10-8) were investigated in additional independent studies, were fine-mapped and putative causal genes identified by gene expression analysis. GWASs of respiratory traits were interrogated to identify whether the signals were driven by existing respiratory disease among the cases and variants were further investigated for wider pleiotropic effects using phenome-wide association studies (PheWASs). RESULTS: From a GWAS of 9714 cases and 48 471 controls, we identified six novel genome-wide significant signals for chronic sputum production including signals in the human leukocyte antigen (HLA) locus, chromosome 11 mucin locus (containing MUC2, MUC5AC and MUC5B) and FUT2 locus. The four common variant associations were supported by independent studies with a combined sample size of up to 2203 cases and 17 627 controls. The mucin locus signal had previously been reported for association with moderate-to-severe asthma. The HLA signal was fine-mapped to an amino acid change of threonine to arginine (frequency 36.8%) in HLA-DRB1 (HLA-DRB1*03:147). The signal near FUT2 was associated with expression of several genes including FUT2, for which the direction of effect was tissue dependent. Our PheWAS identified a wide range of associations including blood cell traits, liver biomarkers, infections, gastrointestinal and thyroid-associated diseases, and respiratory disease. CONCLUSIONS: Novel signals at the FUT2 and mucin loci suggest that mucin fucosylation may be a driver of chronic sputum production even in the absence of diagnosed respiratory disease and provide genetic support for this pathway as a target for therapeutic intervention.

Diagnosing, discarding, or de-VUSsing: A practical guide to (un)targeted metabolomics as variant-transcending functional tests.

PURPOSE: For patients with inherited metabolic disorders (IMDs), any diagnostic delay should be avoided because early initiation of personalized treatment could prevent irreversible health damage. To improve diagnostic interpretation of genetic data, gene function tests can be valuable assets. For IMDs, variant-transcending functional tests are readily available through (un)targeted metabolomics assays. To support the application of metabolomics for this purpose, we developed a gene-based guide to select functional tests to either confirm or exclude an IMD diagnosis. METHODS: Using information from a diagnostic IMD exome panel, Kyoto Encyclopedia of Genes and Genomes, and Inborn Errors of Metabolism Knowledgebase, we compiled a guide for metabolomics-based gene function tests. From our practical experience with this guide, we retrospectively selected illustrative cases for whom combined metabolomic/genomic testing improved diagnostic success and evaluated the effect hereof on clinical management. RESULTS: The guide contains 2047 metabolism-associated genes for which a validated or putative variant-transcending gene function test is available. We present 16 patients for whom metabolomic testing either confirmed or ruled out the presence of a second pathogenic variant, validated or ruled out pathogenicity of variants of uncertain significance, or identified a diagnosis initially missed by genetic analysis. CONCLUSION: Metabolomics-based gene function tests provide additional value in the diagnostic trajectory of patients with suspected IMD by enhancing and accelerating diagnostic success.

Defining the phenotype of PGAP3-congenital disorder of glycosylation; a review of 65 cases.

Biallelic pathogenic variants in PGAP3 cause a rare glycosylphosphatidyl-inositol biogenesis disorder, PGAP3-CDG. This multisystem condition presents with a predominantly neurological phenotype, including developmental delay, intellectual disability, seizures, and hyperphosphatemia. Here, we summarized the phenotype of sixty-five individuals including six unreported individuals from our CDG natural history study with a confirmed PGAP3-CDG diagnosis. Common additional features found in this disorder included brain malformations, behavioral abnormalities, cleft palate, and characteristic facial features. This report aims to review the genetic and metabolic findings and characterize the disease's phenotype while highlighting the necessary clinical approach to improve the management of this rare CDG.

Longitudinal effects of environmental noise and air pollution exposure on autism spectrum disorder and attention-deficit/hyperactivity disorder during adolescence and early adulthood: The TRAILS study.

BACKGROUND: Exposure to ambient noise and air pollution may affect the manifestation and severity of Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD). However, evidence is limited, and most studies solely assessed environmental exposures during pregnancy and early childhood. OBJECTIVE: To examine the longitudinal effects of ambient noise and air pollutants on ASD and ADHD symptom severity during adolescence and early adulthood. METHODS: Using a longitudinal design, we included 2750 children between 10 and 12 years old from the TRacking Adolescents' Individual Lives Survey (TRAILS) in the Netherlands, who were assessed in 6 waves from 2001 to 2017. ASD was measured by the Children's Social Behavior Questionnaire and the Adult Social Behavior Questionnaire. ADHD was measured by Child Behavior Checklist and the Adult Behavior Checklist. Ambient noise and air pollution exposures, including Ozone (O3), soot, sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter 2.5 (PM2.5), and PM10 were modeled at the residential level according to standardized protocols. The longitudinal associations between exposures and symptom outcomes were examined using linear mixed models. RESULTS: We found evidence that higher levels of exposure to PM were associated with more severe ASD and ADHD symptoms. This association decreased over time. We did not observe any other consistent associations of noise or other air pollutants with ASD and ADHD severity. CONCLUSION: The current study provides evidence for the negative impact of PM on ASD and ADHD symptoms. We did not find evidence of the negative health impact of other air pollutants and noise exposures on ASD or ADHD symptoms. Our study adds more evidence on the presence of associations between PM air pollution and neurodevelopmental diseases among adolescents and young adults.

Pulmonary Function and Blood DNA Methylation: A Multiancestry Epigenome-Wide Association Meta-analysis.

Rationale: Methylation integrates factors present at birth and modifiable across the lifespan that can influence pulmonary function. Studies are limited in scope and replication. Objectives: To conduct large-scale epigenome-wide meta-analyses of blood DNA methylation and pulmonary function. Methods: Twelve cohorts analyzed associations of methylation at cytosine-phosphate-guanine probes (CpGs), using Illumina 450K or EPIC/850K arrays, with FEV1, FVC, and FEV1/FVC. We performed multiancestry epigenome-wide meta-analyses (total of 17,503 individuals; 14,761 European, 2,549 African, and 193 Hispanic/Latino ancestries) and interpreted results using integrative epigenomics. Measurements and Main Results: We identified 1,267 CpGs (1,042 genes) differentially methylated (false discovery rate, <0.025) in relation to FEV1, FVC, or FEV1/FVC, including 1,240 novel and 73 also related to chronic obstructive pulmonary disease (1,787 cases). We found 294 CpGs unique to European or African ancestry and 395 CpGs unique to never or ever smokers. The majority of significant CpGs correlated with nearby gene expression in blood. Findings were enriched in key regulatory elements for gene function, including accessible chromatin elements, in both blood and lung. Sixty-nine implicated genes are targets of investigational or approved drugs. One example novel gene highlighted by integrative epigenomic and druggable target analysis is TNFRSF4. Mendelian randomization and colocalization analyses suggest that epigenome-wide association study signals capture causal regulatory genomic loci. Conclusions: We identified numerous novel loci differentially methylated in relation to pulmonary function; few were detected in large genome-wide association studies. Integrative analyses highlight functional relevance and potential therapeutic targets. This comprehensive discovery of potentially modifiable, novel lung function loci expands knowledge gained from genetic studies, providing insights into lung pathogenesis.

Tularemia Transmission to Humans, the Netherlands, 2011-2021.

We used national registry data on human cases of Francisella tularensis subspecies holarctica infection to assess transmission modes among all 26 autochthonous cases in the Netherlands since 2011. The results indicate predominance of terrestrial over aquatic animal transmission sources. We recommend targeting disease-risk communication toward hunters, recreationists, and outdoor professionals.

Genetic, biochemical, and clinical spectrum of patients with mitochondrial trifunctional protein deficiency identified after the introduction of newborn screening in the Netherlands.

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is included in many newborn screening (NBS) programs. Acylcarnitine-based NBS for LCHADD not only identifies LCHADD, but also the other deficiencies of the mitochondrial trifunctional protein (MTP), a multi-enzyme complex involved in long-chain fatty acid ß-oxidation. Besides LCHAD, MTP harbors two additional enzyme activities: long-chain enoyl-CoA hydratase (LCEH) and long-chain ketoacyl-CoA thiolase (LCKAT). Deficiency of one or more MTP activities causes generalized MTP deficiency (MTPD), LCHADD, LCEH deficiency (not yet reported), or LCKAT deficiency (LCKATD). To gain insight in the outcomes of MTP-deficient patients diagnosed after the introduction of NBS for LCHADD in the Netherlands, a retrospective evaluation of genetic, biochemical, and clinical characteristics of MTP-deficient patients, identified since 2007, was carried out. Thirteen patients were identified: seven with LCHADD, five with MTPD, and one with LCKATD. All LCHADD patients (one missed by NBS, clinical diagnosis) and one MTPD patient (clinical diagnosis) were alive. Four MTPD patients and one LCKATD patient developed cardiomyopathy and died within 1 month and 13 months of life, respectively. Surviving patients did not develop symptomatic hypoglycemia, but experienced reversible cardiomyopathy and rhabdomyolysis. Five LCHADD patients developed subclinical neuropathy and/or retinopathy. In conclusion, patient outcomes were highly variable, stressing the need for accurate classification of and discrimination between the MTP deficiencies to improve insight in the yield of NBS for LCHADD. NBS allowed the prevention of symptomatic hypoglycemia, but current treatment options failed to treat cardiomyopathy and prevent long-term complications. Moreover, milder patients, who might benefit from NBS, were missed due to normal acylcarnitine profiles.

Neurocognitive outcome and mental health in children with tyrosinemia type 1 and phenylketonuria: A comparison between two genetic disorders affecting the same metabolic pathway.

Tyrosinemia type 1 (TT1) and phenylketonuria (PKU) are both inborn errors of phenylalanine-tyrosine metabolism. Neurocognitive and behavioral outcomes have always featured in PKU research but received less attention in TT1 research. This study aimed to investigate and compare neurocognitive, behavioral, and social outcomes of treated TT1 and PKU patients. We included 33 TT1 patients (mean age 11.24 years; 16 male), 31 PKU patients (mean age 10.84; 14 male), and 58 age- and gender-matched healthy controls (mean age 10.82 years; 29 male). IQ (Wechsler-subtests), executive functioning (the Behavioral Rating Inventory of Executive Functioning), mental health (the Achenbach-scales), and social functioning (the Social Skills Rating System) were assessed. Results of TT1 patients, PKU patients, and healthy controls were compared using Kruskal-Wallis tests with post-hoc Mann-Whitney U tests. TT1 patients showed a lower IQ and poorer executive functioning, mental health, and social functioning compared to healthy controls and PKU patients. PKU patients did not differ from healthy controls regarding these outcome measures. Relatively poor outcomes for TT1 patients were particularly evident for verbal IQ, BRIEF dimensions "working memory", "plan and organize" and "monitor", ASEBA dimensions "social problems" and "attention problems", and for the SSRS "assertiveness" scale (all p values <0.001). To conclude, TT1 patients showed cognitive impairments on all domains studied, and appeared to be significantly more affected than PKU patients. More attention should be paid to investigating and monitoring neurocognitive outcome in TT1 and research should focus on explaining the underlying pathophysiological mechanism.

Occupational exposure to gases/fumes and mineral dust affect DNA methylation levels of genes regulating expression.

Many workers are daily exposed to occupational agents like gases/fumes, mineral dust or biological dust, which could induce adverse health effects. Epigenetic mechanisms, such as DNA methylation, have been suggested to play a role. We therefore aimed to identify differentially methylated regions (DMRs) upon occupational exposures in never-smokers and investigated if these DMRs associated with gene expression levels. To determine the effects of occupational exposures independent of smoking, 903 never-smokers of the LifeLines cohort study were included. We performed three genome-wide methylation analyses (Illumina 450 K), one per occupational exposure being gases/fumes, mineral dust and biological dust, using robust linear regression adjusted for appropriate confounders. DMRs were identified using comb-p in Python. Results were validated in the Rotterdam Study (233 never-smokers) and methylation-expression associations were assessed using Biobank-based Integrative Omics Study data (n = 2802). Of the total 21 significant DMRs, 14 DMRs were associated with gases/fumes and 7 with mineral dust. Three of these DMRs were associated with both exposures (RPLP1 and LINC02169 (2×)) and 11 DMRs were located within transcript start sites of gene expression regulating genes. We replicated two DMRs with gases/fumes (VTRNA2-1 and GNAS) and one with mineral dust (CCDC144NL). In addition, nine gases/fumes DMRs and six mineral dust DMRs significantly associated with gene expression levels. Our data suggest that occupational exposures may induce differential methylation of gene expression regulating genes and thereby may induce adverse health effects. Given the millions of workers that are exposed daily to occupational exposures, further studies on this epigenetic mechanism and health outcomes are warranted.

COPD-derived fibroblasts secrete higher levels of senescence-associated secretory phenotype proteins.

COPD-derived fibroblasts have increased cellular senescence. Senescent cell accumulation can induce tissue dysfunction by their senescence-associated secretory phenotype (SASP). We aimed to determine the SASP of senescent fibroblasts and COPD-derived lung fibroblasts, including severe, early-onset (SEO)-COPD. SASP protein secretion was measured after paraquat-induced senescence in lung fibroblasts using Olink Proteomics and compared between (SEO-)COPD-derived and control-derived fibroblasts. We identified 124 SASP proteins of senescent lung fibroblasts, of which 42 were secreted at higher levels by COPD-derived fibroblasts and 35 by SEO-COPD-derived fibroblasts compared with controls. Interestingly, the (SEO-)COPD-associated SASP included proteins involved in chronic inflammation, which may contribute to (SEO-)COPD pathogenesis.

Link between increased cellular senescence and extracellular matrix changes in COPD.

Chronic obstructive pulmonary disease (COPD) is associated with features of accelerated aging, including cellular senescence, DNA damage, oxidative stress, and extracellular matrix (ECM) changes. We propose that these features are particularly apparent in patients with severe, early-onset (SEO)-COPD. Whether fibroblasts from COPD patients display features of accelerated aging and whether this is also present in relatively young SEO-COPD patients is unknown. Therefore, we aimed to determine markers of aging in (SEO)-COPD-derived lung fibroblasts and investigate the impact on ECM. Aging hallmarks and ECM markers were analyzed in lung fibroblasts from SEO-COPD and older COPD patients and compared with fibroblasts from matched non-COPD groups (n = 9-11 per group), both at normal culture conditions and upon Paraquat-induced senescence. COPD-related differences in senescence and ECM expression were validated in lung tissue. Higher levels of cellular senescence, including senescence-associated ß-galactosidase (SA-ß-gal)-positive cells (19% for COPD vs. 13% for control) and p16 expression, DNA damage (γ-H2A.X-positive nuclei), and oxidative stress (MGST1) were detected in COPD compared with control-derived fibroblasts. Most effects were also different in SEO-COPD, with SA-ß-gal-positive cells only being significant in SEO-COPD vs. matched controls. Lower decorin expression in COPD-derived fibroblasts correlated with higher p16 expression, and this association was confirmed in lung tissue. Paraquat treatment induced cellular senescence along with clear changes in ECM expression, including decorin. Fibroblasts from COPD patients, including SEO-COPD, display higher levels of cellular senescence, DNA damage, and oxidative stress. The association between cellular senescence and ECM expression changes may suggest a link between accelerated aging and ECM dysregulation in COPD.

Does the 48-hour BH4 loading test miss responsive PKU patients?

BACKGROUND: Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism. Besides dietary treatment, some patients are responsive to and treated with tetrahydrobiopterin (BH4). Our primary objective was to examine whether the 48-hour BH4 loading test misses BH4-responsive PKU patients. Secondary, we assessed if it would be beneficial to 1) use a cut-off value of 20% Phe reduction instead of commonly used 30%, and 2) extend the loading test to 7 days. METHODS: 24 patients with a 20-30% decrease of blood Phe levels during their initial 48-hour BH4 loading test or at least one mutation associated with long-term BH4 responsiveness, were invited to participate. 22 of them underwent the 7-day BH4 loading test. During the BH4 loading test, BH4 was administered orally once daily for 7 days (20 mg/kg/day). Blood samples on filter paper were collected at 13 time points. Potential BH4 responders (≥20% decrease in blood Phe concentrations at ≥1 moment within the first 48 h or ≥30% at ≥1 moment during the entire test) underwent a treatment trial to assess true long-term responsiveness (≥30% decrease of Phe levels compared to baseline and/or ≥50% increase in natural protein tolerance in accordance with the Dutch guidelines before 2017). The duration of the treatment trial varied from 2 to 18 months. RESULTS: Of the 22 patients who completed the 7-day BH4 loading test, 2 were excluded, 8 had negative tests and 12 were considered to be potential BH4 responders. Of these 12 potential BH4-responsive PKU patients, 5 turned out to be false positive, 6 true-responder and 1 was withdrawn. CONCLUSION: Even though the 48-hour BH4 loading test has proven its efficacy in the past, a full week may be necessary to detect all responders. So, if blood Phe concentrations during the 48-hour BH4 test shows a clear tendency, but not sufficient decrease, a full week (with only measurements each 24 h) could be offered. A threshold of ≥20% decrease within 48 h is not useful for predicting true BH4 responsiveness.