N-Glycosylation Profiles of Immunoglobulin G and Future Cardiovascular Events.

BACKGROUND: Posttranslational glycosylation of IgG can modulate its inflammatory capacity through structural variations. We examined the association of baseline IgG N-glycans and an IgG glycan score with incident cardiovascular disease (CVD). METHODS: IgG N-glycans were measured in 2 nested CVD case-control studies: JUPITER (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin; NCT00239681; primary prevention; discovery; Npairs=162); and TNT trial (Treating to New Targets; NCT00327691; secondary prevention; validation; Npairs=397). Using conditional logistic regression, we investigated the association of future CVD with baseline IgG N-glycans and a glycan score adjusting for clinical risk factors (statin treatment, age, sex, race, lipids, hypertension, and smoking) in JUPITER. Significant associations were validated in TNT, using a similar model further adjusted for diabetes. Using least absolute shrinkage and selection operator regression, an IgG glycan score was derived in JUPITER as a linear combination of selected IgG N-glycans. RESULTS: Six IgG N-glycans were associated with CVD in both studies: an agalactosylated glycan (IgG-GP4) was positively associated, while 3 digalactosylated glycans (IgG glycan peaks 12, 13, 14) and 2 monosialylated glycans (IgG glycan peaks 18, 20) were negatively associated with CVD after multiple testing correction (overall false discovery rate <0.05). Four selected IgG N-glycans comprised the IgG glycan score, which was associated with CVD in JUPITER (adjusted hazard ratio per glycan score SD, 2.08 [95% CI, 1.52-2.84]) and validated in TNT (adjusted hazard ratio per SD, 1.20 [95% CI, 1.03-1.39]). The area under the curve changed from 0.693 for the model without the score to 0.728 with the score in JUPITER (PLRT=1.1×10-6) and from 0.635 to 0.637 in TNT (PLRT=0.017). CONCLUSIONS: An IgG N-glycan profile was associated with incident CVD in 2 populations (primary and secondary prevention), involving an agalactosylated glycan associated with increased risk of CVD, while several digalactosylated and sialylated IgG glycans associated with decreased risk. An IgG glycan score was positively associated with future CVD.

Storage stability and HILIC-UHPLC-FLR analysis of immunoglobulin G N-glycome from saliva.

Immunoglobulin G (IgG) is the most abundant antibody in the blood and plays a critical role in host immune defense against infectious agents. Glycosylation is known to modulate the effector functions of IgG and is involved in disease development and progression. It is no surprise that the N-glycome of IgG from plasma has already been proposed as a biomarker for various physiological and pathological conditions. However, because saliva is easy to collect, it could be useful for exploring the functional role of salivary IgG N-glycosylation and its potential as a diagnostic biomarker. Therefore, in this study, we described a method for N-glycome analysis of IgG from saliva samples. Salivary IgG N-glycans were analyzed by ultra-high-performance liquid chromatography based on hydrophilic interactions with fluorescence detection (HILIC-UHPLC-FLR). In addition, we compared IgG N-glycan profiles from saliva with those from plasma, assessed the stability of salivary IgG N-glycan profiles under different storage conditions, and evaluated the effects of using a saliva preservation medium. This study provides an ultrasensitive UHPLC method for the analysis of total IgG N-glycosylation from saliva, gives insight into storage stability of salivary IgG, and highlights its (dis)advantages for further biomarker-related research.

Susceptibility of Human Plasma N-glycome to Low-Calorie and Different Weight-Maintenance Diets.

Aberrant plasma protein glycosylation is associated with a wide range of diseases, including diabetes, cardiovascular, and immunological disorders. To investigate plasma protein glycosylation alterations due to weight loss and successive weight-maintenance diets, 1850 glycomes from participants of the Diogenes study were analyzed using Ultra-High-Performance Liquid Chromatography (UHPLC). The Diogenes study is a large dietary intervention study in which participants were subjected to a low-calorie diet (LCD) followed by one of five different weight-maintenance diets in a period of 6 months. The most notable alterations of the plasma glycome were 8 weeks after the subjects engaged in the LCD; a significant increase in low-branched glycan structures, accompanied by a decrease in high-branched glycan structures. After the LCD period, there was also a significant rise in N-glycan structures with antennary fucose. Interestingly, we did not observe significant changes between different diets, and almost all effects we observed immediately after the LCD period were annulled during the weight-maintenance diets period.

Replication of 15 loci involved in human plasma protein N-glycosylation in 4802 samples from four cohorts.

Human protein glycosylation is a complex process, and its in vivo regulation is poorly understood. Changes in glycosylation patterns are associated with many human diseases and conditions. Understanding the biological determinants of protein glycome provides a basis for future diagnostic and therapeutic applications. Genome-wide association studies (GWAS) allow to study biology via a hypothesis-free search of loci and genetic variants associated with a trait of interest. Sixteen loci were identified by three previous GWAS of human plasma proteome N-glycosylation. However, the possibility that some of these loci are false positives needs to be eliminated by replication studies, which have been limited so far. Here, we use the largest set of samples so far (4802 individuals) to replicate the previously identified loci. For all but one locus, the expected replication power exceeded 95%. Of the 16 loci reported previously, 15 were replicated in our study. For the remaining locus (near the KREMEN1 gene), the replication power was low, and hence, replication results were inconclusive. The very high replication rate highlights the general robustness of the GWAS findings as well as the high standards adopted by the community that studies genetic regulation of protein glycosylation. The 15 replicated loci present a good target for further functional studies. Among these, eight loci contain genes encoding glycosyltransferases: MGAT5, B3GAT1, FUT8, FUT6, ST6GAL1, B4GALT1, ST3GAL4 and MGAT3. The remaining seven loci offer starting points for further functional follow-up investigation into molecules and mechanisms that regulate human protein N-glycosylation in vivo.

Increased yield of enzymatic synthesis by chromatographic selection of different N-glycoforms of yeast invertase.

Invertases are glycosidases applied for synthesis of alkyl glycosides that are important and effective surfactants. Stability of invertases in the environment with increased content of organic solvent is crucial for increase of productivity of glycosidases. Their stability is significantly influenced by N-glycosylation. However, yeast N-glycosylation pathways may synthesize plethora of N-glycan structures. A total natural crude mixture of invertase glycoforms (EINV) extracted from Saccharomyces cerevisiae was subfractionated by anion-exchange chromatography on industrial monolithic supports to obtain different glycoforms (EINV1-EINV3). Separated glycoforms exhibited different stabilities in water-alcohol solutions that are in direct correlation with the amount of phosphate bound to N-glycans. Observed differences in stability of different invertase glycoforms were used to improve productivity of methyl ß-d-fructofuranoside (MF) synthesis. The efficiency and yield of MF synthesis were improved more than 50% when the most stabile glycoform bearing the lowest amount of phosphorylated N-glycans is selected and utilized. These data underline the importance of analysis of glycan structures attached to glycoproteins, demonstrate different impact of N-glycans on the surface charge and enzyme stability in regard to particular reaction environment, and provide a platform for improvement of yield of industrial enzymatic synthesis by chromatographic selection of glycoforms on monolithic supports.

Glycosylation Profile of Immunoglobulin G Is Cross-Sectionally Associated With Cardiovascular Disease Risk Score and Subclinical Atherosclerosis in Two Independent Cohorts.

RATIONALE: One measure of protein glycosylation (GlycA) has been reported to predict higher cardiovascular risk by reflecting inflammatory pathways. OBJECTIVE: The main objective of this study is to assess the role of a comprehensive panel of IgG glycosylation traits on traditional risk factors for cardiovascular disease and on presence of subclinical atherosclerosis in addition to GlycA. METHODS AND RESULTS: We measured 76 IgG glycosylation traits in 2970 women (age range, 40-79 years) from the TwinsUK cohort and correlated it to their estimated 10-year atherosclerotic cardiovascular disease risk score and their carotid and femoral plaque measured by ultrasound imaging. Eight IgG glycan traits are associated with the 10-year atherosclerotic cardiovascular disease risk score after adjusting for multiple tests and for individual risk factors-5 with increased risk and 3 with decreased risk. These glycans replicated in 967 women from ORCADES cohort (Orkney Complex Disease Study), and 6 of them were also associated in 845 men. A linear combination of IgG glycans and GlycA is also associated with presence of carotid (odds ratio, 1.55; 95% confidence interval, 1.25-1.93; P=7.5×10-5) and femoral (odds ratio, 1.32; 95% confidence interval, 1.06-1.64; P=0.01) plaque in a subset of women with atherosclerosis data after adjustment for traditional risk factors. One specific glycosylation trait, GP18-the percentage of FA2BG2S1 glycan in total IgG glycans, was negatively correlated with very-low-density lipoprotein and triglyceride levels in serum and with presence of carotid plaque (odds ratio, 0.60; 95% confidence interval, 0.50-0.71; P=5×10-4). CONCLUSIONS: We find molecular pathways linking IgG to arterial lesion formation. Glycosylation traits are independently associated with subclinical atherosclerosis. One specific trait related to the sialylated N-glycan is negatively correlated with cardiovascular disease risk, very-low-density lipoprotein and triglyceride serum levels, and presence of carotid plaque.

N-glycome of the Lysosomal Glycocalyx is Altered in Niemann-Pick Type C Disease (NPC) Model Cells.

Increasing evidence implicates lysosomal dysfunction in the pathogenesis of neurodegenerative diseases, including the rare inherited lysosomal storage disorders (LSDs) and the most common neurodegenerative diseases, such as Alzheimer's and Parkinson's disease (AD and PD). Although the triggers of the lysosomal impairment may involve the accumulated macromolecules or dysfunction of the lysosomal enzymes, the role of the lysosomal glycocalyx in the lysosomal (dys)function has not been studied. The goal of this work was to analyze whether there are changes in the lysosomal glycocalyx in a cellular model of a LSD Niemann-Pick type C disease (NPC). Using the ferrofluid nanoparticles we isolated lysosomal organelles from NPC1-null and CHOwt cells. The magnetically isolated lysosomal fractions were enriched with the lysosomal marker protein LAMP1 and showed the key features of NPC disease: 3-fold higher cholesterol content and 4-5 fold enlarged size of the particles compared with the lysosomal fractions of wt cells. These lysosomal fractions were further processed to isolate lysosomal membrane proteins using Triton X-114 and their N-glycome was analyzed by HILIC-UPLC. N-glycans presented in each chromatographic peak were elucidated using MALDI-TOF/TOF-MS. We detected changes in the N-glycosylation pattern of the lysosomal glycocalyx of NPC1-null versus wt cells which involved high-mannose and sialylated N-glycans. To the best of our knowledge this study is the first to report N-glycome profiling of the lysosomal glycocalyx in NPC disease cellular model and the first to report the specific changes in the lysosomal glycocalyx in NPC1-null cells. We speculate that changes in the lysosomal glycocalyx may contribute to lysosomal (dys)function. Further glycome profiling of the lysosomal glycocalyx in other LSDs as well as the most common neurodegenerative diseases, such as AD and PD, is necessary to better understand the role of the lysosomal glycocalyx and to reveal its potential contribution in lysosomal dysfunction leading to neurodegeneration.

Comprehensive N-glycosylation analysis of immunoglobulin G from dried blood spots.

Immunoglobulin G (IgG) glycans are emerging as a new putative biomarker for biological age and different diseases, requiring a robust workflow for IgG glycome analysis, ideally beginning with a simple and undemanding sampling procedure. Here, we report the first comprehensive study on total N-glycans of IgG isolated from dried blood spots (DBSs), which was performed in a high-throughput mode. We compared the IgG N-glycan profiles originating from DBS with those originating from plasma, compared different media for DBS collection, evaluated analytical variation and assessed IgG N-glycan profile stability for different storage conditions. In conclusion, we show that DBSs are a good and stable source material for a robust IgG N-glycan analysis by ultra-performance liquid chromatography, suitable for blood sampling in conditions where no trained personnel and necessary laboratory equipment are available.

High throughput profiling of whole plasma N-glycans in type II diabetes mellitus patients and healthy individuals: A perspective from a Ghanaian population.

Aberrant protein glycosylation may reflect changes in cell metabolism of type II diabetes mellitus (T2DM) and offers fresh vistas for discovering potential biomarkers. However, the functional significance of T2DM N-glycan alterations is underexplored, since to date, N-glycan profiling studies have been performed in selected populations. Geographically and genetically isolated populations are needed for validation of specific biomarkers. This age-sex matched cross sectional study comprising 232 T2DM patients and 219 controls was conducted in Ghana, Western Africa. Blood plasma samples were collected for clinical assessment after which plasma N-glycans were freed and analysed by ultra-performance liquid chromatography (UPLC). High branching (HB) [W = 46328; q = 0.00072], tri-galactosylated (G3) [W = 44076; q = 0.00096], antennary fucosylated (FUC_A) [W = 43055; q = 0.0000763], and triantennary (TRIA) [W = 44624; q = 0.0025], N-glycan structures were increased in T2DM whereas low branching (LB) [W = 46328; q = 0.00072], non-sialylated (S0) [W = 46929; q = 0.00292], monogalactosylation (G1) [W = 44091; q = 0.0000763], core fucosylation (FUC_C), [W = 46497; q = 0.00096], biantennary galactosylation (A2G) [W = 45663; q = 0.000763], and biantennary (BA) [W = 46376; q = 0.00072], structures were decreased compared to controls. Nine N-glycan peaks (GPs (GP1, GP4, GP7, GP11, GP17, GP19, GP22, GP26, GP29)) were found to predict case status based on Akaike's information criterion (AIC) and Bayesian information criterion (BIC) model selection. Adjusting for age, sex and other co-variates in this model yielded an area under the curve (AUC) of 80.5% with sensitivity of 79% and specificity of 73%, indicating the predicting power of N-glycans as robust biomarkers. Our results show that hyperglycemia influences N-glycan complexities among Ghanaians. N-glycan profiling in distinct populations has affirmed the potentiality of N-glycan profiles as generic biomarkers which may facilitate better prognosis for T2DM.

Correction to: Increased plasma N-glycome complexity is associated with higher risk of type 2 diabetes.

The authors regret that Nish Chaturvedi's name was spelt incorrectly in the author list. The details given in this correction are correct.

Low galactosylation of IgG associates with higher risk for future diagnosis of rheumatoid arthritis during 10 years of follow-up.

Antibodies are known to have an important role in the development of rheumatoid arthritis (RA), one of the most prevalent chronic inflammatory diseases which primarily involves the joints. Most RA patients develop autoantibodies against immunoglobulin G (IgG) and changes in IgG glycosylation have been associated with RA. We undertook this study to determine whether altered IgG glycosylation precedes the disease diagnosis. We studied IgG glycosylation in RA in two prospective cohorts (N = 14,749) by measuring 28 IgG glycan traits in 179 subjects who developed RA within 10-years follow-up and 358 matched controls. Ultra-performance liquid chromatography method based on hydrophilic interactions (HILIC-UPLC) was used to analyse IgG glycans. Future RA diagnosis associated with traits related to lower galactosylation and sialylation of IgG when comparing the cases to the matched controls. In RA cases, these traits did not correlate with the time between being recruited to the study and being diagnosed with RA (median time 4.31 years). The difference in IgG glycosylation was relatively stable and present years before diagnosis. This indicates that long-acting factors affecting IgG glycome composition are among the underlying mechanisms of RA and that decreased galactosylation is a pre-existing risk factor involved in the disease development.

Immunoglobulin G glycosylation in aging and diseases.

The Immunoglobulin G (IgG) glycome is well known for its heterogeneity and shows a significant degree of variation within populations. IgG glycome composition is influenced both by genes and by environment, making it an excellent biomarker of a person's general health state, i.e. biological age. IgG glycosylation appears to be highly regulated, both during homeostasis and in cases of its disturbance. Changes in IgG glycosylation patterns have been observed in aging and in various diseases. Differential IgG glycosylation is known to modulate IgG effector functions and is involved in disease development and progression, representing both a predisposition and a functional mechanism involved in disease pathology. This makes IgG glycosylation analysis a promising add-on to improve existing disease biomarkers.

IgG glycosylation and DNA methylation are interconnected with smoking.

BACKGROUND: Glycosylation is one of the most common post-translation modifications with large influences on protein structure and function. The effector function of immunoglobulin G (IgG) alters between pro- and anti-inflammatory, based on its glycosylation. IgG glycan synthesis is highly complex and dynamic. METHODS: With the use of two different analytical methods for assessing IgG glycosylation, we aim to elucidate the link between DNA methylation and glycosylation of IgG by means of epigenome-wide association studies. In total, 3000 individuals from 4 cohorts were analyzed. RESULTS: The overlap of the results from the two glycan measurement panels yielded DNA methylation of 7 CpG-sites on 5 genomic locations to be associated with IgG glycosylation: cg25189904 (chr.1, GNG12); cg05951221, cg21566642 and cg01940273 (chr.2, ALPPL2); cg05575921 (chr.5, AHRR); cg06126421 (6p21.33); and cg03636183 (chr.19, F2RL3). Mediation analyses with respect to smoking revealed that the effect of smoking on IgG glycosylation may be at least partially mediated via DNA methylation levels at these 7 CpG-sites. CONCLUSION: Our results suggest the presence of an indirect link between DNA methylation and IgG glycosylation that may in part capture environmental exposures. GENERAL SIGNIFICANCE: An epigenome-wide analysis conducted in four population-based cohorts revealed an association between DNA methylation and IgG glycosylation patterns. Presumably, DNA methylation mediates the effect of smoking on IgG glycosylation.

Increased plasma N-glycome complexity is associated with higher risk of type 2 diabetes.

AIMS/HYPOTHESIS: Better understanding of type 2 diabetes and its prevention is a pressing need. Changes in human plasma N-glycome are associated with many diseases and represent promising diagnostic and prognostic biomarkers. Variations in glucose metabolism directly affect glycosylation through the hexosamine pathway but studies of plasma glycome in type 2 diabetes are scarce. The aim of this study was to determine whether plasma protein N-glycome is changed in individuals who are at greater risk of developing type 2 diabetes. METHODS: Using a chromatographic approach, we analysed N-linked glycans from plasma proteins in two populations comprising individuals with registered hyperglycaemia during critical illness (increased risk for development of type 2 diabetes) and individuals who stayed normoglycaemic during the same condition: AcuteInflammation (59 cases vs 49 controls) and AcuteInflammation Replication (52 cases vs 14 controls) populations. N-glycome was also studied in individuals from FinRisk (37 incident cases of type 2 diabetes collected at baseline vs 37 controls), Orkney Complex Disease Study (ORCADES; 94 individuals with HbA1c > 6.5% [47.5 mmol/mol] vs 658 controls) and Southall and Brent Revisited (SABRE) cohort studies (307 individuals with HbA1c > 6.5% [47.5 mmol/mol] vs 307 controls). RESULTS: Individuals with increased risk for diabetes type 2 development (AcuteInflammation and AcuteInflammation Replication populations), incident cases of type 2 diabetes collected at baseline (FinRisk population) and individuals with elevated HbA1c (ORCADES and SABRE populations) all presented with increased branching, galactosylation and sialylation of plasma protein N-glycans and these changes were of similar magnitude. CONCLUSIONS/INTERPRETATION: Increased complexity of plasma N-glycan structures is associated with higher risk of developing type 2 diabetes and poorer regulation of blood glucose levels. Although further research is needed, this finding could offer a potential new approach for improvement in prevention of diabetes and its complications.

Enrichment of hydrophobic membrane proteins using Triton X-114 and subsequent analysis of their N-glycosylation.

BACKGROUND: Numerous proteins depend on correct glycosylation for their proper function and nearly all membrane, as well as secreted, proteins are glycosylated. Glycosylation of membrane proteins plays a crucial role in many processes including the intercellular recognition and intermolecular interactions on the cell surface. The composition of N-glycans attached to membrane proteins has not been sufficiently studied due to the lack of efficient and reproducible analytical methods. METHODS: The aim of this study was to optimise cloud-point extraction (CPE) of membrane proteins with the non-ionic detergent Triton X-114 and analyse their N-glycosylation using hydrophilic interaction liquid chromatography (HILIC-UPLC). Purification of isolated proteins from the excess of detergent proved to be the key step. Therefore, several purification procedures were tested to efficiently remove detergent, while retaining maximum protein recoveries. RESULTS: CPE showed to be an efficient method to simultaneously extract membrane and soluble proteins, which subsequently resulted in different N-glycan profiles of the aforementioned protein groups. The resulting protocol showed satisfactory reproducibility and potential for N-glycan analysis of both membrane and intracellular (soluble) proteins from different kinds of biological material. CONCLUSIONS: This method can be used as a new analytical tool for reliable detection and quantification of oligomannose and complex type N-glycans attached to membrane proteins, thus serving to distinguish between differences in cell types and states. GENERAL SIGNIFICANCE: The simple method was successfully optimised to generate reliable HILIC-UPLC profiles of N-glycans released from membrane proteins. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Early detection of COPD patients in GOLD 0 population: an observational non-interventional cohort study - MARKO study.

BACKGROUND: Main risk factor for the development of chronic obstructive pulmonary disease (COPD) is smoking, although only less than 1/3 of smokers develop clinically manifest COPD. COPD's progressive nature with high disability and mortality makes it plausible to detect it as early as possible thus allowing for an early intervention. The only tool for an early diagnosis that could be used on the global scale is spirometry, even though symptoms and deprivation of health related quality of life (HRQoL) precede relevant spirometric changes. Existing HRQoL questionnaires are too complicated or not developed for an early detection of COPD. The aim of our study was to develop a new simple HRQoL tool that will allow (alone or in combination with other markers) early detection of patients with COPD. METHODS: A multicenter prospective cohort study recruiting 500 subjects at risk for COPD (smokers/ex-smokers ≥20 pack-years, 40-65 years, both sexes, with no prior diagnosis of COPD) will be carried out in two phases: (1) cross-sectional - development and validation of a new questionnaire; and (2) prospective - follow-up of a cohort of patients at risk for COPD. Subjects were recruited by 25 GPs and assessed for COPD by dedicated pulmonologists in 7 hospital centers using a predefined protocol: HRQoL, history, physical, blood sampling, exhaled breath temperature (EBT), lung function, 6-min walk test (6MWT). Patients without COPD and those in GOLD stage 1 at initial assessment will be reassessed for disease progression by the same pulmonologist after 2 and 5 years. DISCUSSION: This is one of the first cohort studies attempting to establish the incidence of COPD in the pre-symptomatic stage before significant end organ damage. We intend to assess the validity, predictability and discriminative power ('healthy' smokers vs. pre-symptomatic phase in newly developed COPD) of newly developed HRQoL tool alone or in combination with other markers; EBT, lung function, 6MWT, genomics, transcriptomics, proteomics). We expect that the results of this study can improve our understanding of the development of COPD, identify some new underlying pathophysiological pathways, and offer to sensitive smokers/ex-smokers new preventive and early intervention measures thus improving the management of COPD. TRIAL REGISTRATION: Clinicaltrial.gov NCT01550679 retrospectively registered February 28, 2012.

Glycosylation Profile of IgG in Moderate Kidney Dysfunction.

Glycans constitute the most abundant and diverse form of the post-translational modifications, and animal studies have suggested the involvement of IgG glycosylation in mechanisms of renal damage. Here, we explored the associations between IgG glycans and renal function in 3274 individuals from the TwinsUK registry. We analyzed the correlation between renal function measured as eGFR and 76 N-glycan traits using linear regressions adjusted for covariates and multiple testing in the larger population. We replicated our results in 31 monozygotic twin pairs discordant for renal function. Results from both analyses were then meta-analyzed. Fourteen glycan traits were associated with renal function in the discovery sample (P<6.5×10(-4)) and remained significant after validation. Those glycan traits belong to three main glycosylation features: galactosylation, sialylation, and level of bisecting N-acetylglucosamine of the IgG glycans. These results show the role of IgG glycosylation in kidney function and provide novel insight into the pathophysiology of CKD and potential diagnostic and therapeutic targets.

Diagnostic accuracy of a pocket screening spirometer in diagnosing chronic obstructive pulmonary disease in general practice: a cross sectional validation study using tertiary care as a reference.

BACKGROUND: COPD-6™ is a lung function testing device for a rapid pre-spirometry testing to screen-out at-risk individuals not having COPD and indicating those at risk. The aim of this study was to validate COPD-6™ lung function testing (index test) in general practice in discriminating patients with COPD out of the population at risk - smokers/ex-smokers with no previous diagnosis of COPD, using measurements at tertiary care as reference standard. METHODS: Consecutive 227 subjects (115 women, 185 smokers/42 ex-smokers, ≥20 pack-years) with no previous diagnosis of COPD, aged 52.5 (SD 6.8) years from 26 general practitioners (GPs) were recruited, lung function tested with COPD-6™, referred to the tertiary institution for repeated COPD-6™ testing followed by spirometry with a bronchodilator (salbutamol), examination, and pulmonologist consultation for the diagnosis and severity of COPD. RESULTS: COPD was diagnosed in 43 subjects (18.9 %), with an AUC of 0.827 (95 % CI 0.769-0.875, P < 0.001) for the diagnosis of COPD when lung function was measured using COPD-6™ in GP's office with a specificity of 100 % (95 % CI, 97.95-100 %) but a very low sensitivity of 32.56 % (95 % CI, 20.49-47.48 %). Significant agreement for forced expiratory volume in 1 s measured at GP's office and at lung function lab was found (mean difference 0.01 L, p = 0.667) but not for other measured parameters (p < 0.001 for all). CONCLUSIONS: Our study results point out that active case finding in a population at risk for COPD should be instituted (almost 20 % of undiagnosed COPD). Based on our results lung function testing with COPD-6™ can substitute spirometry testing in cases where it is not readily available to the patient/physician taken into account that the traditional FEV1/FEV6 cutoff value of <0.7 is not the only criterion for diagnosis and/or further referral. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01550679 Registered 28 September 2014, retrospectively registered.

Exhaled Breath Temperature as a Novel Marker of Future Development of COPD: Results of a Follow-Up Study in Smokers.

Although only less than one-third of smokers develop COPD, early marker(s) of COPD development are lacking. The aim of this research was to assess the ability of an average equilibrium exhaled breath temperature (EBT) in identifying susceptibility to cigarette smoke so as to predict COPD development in smokers at risk. The study was a part of a multicenter prospective cohort study in current smokers (N = 140, both sexes, 40-65 years, ≥20 pack-years) with no prior diagnosis of COPD. Diagnostic workup includes history, physical, quality of life, hematology and highly sensitive CRP, EBT before and after smoking a cigarette, lung function with bronchodilator test, and 6-minute walk test. Patients without a diagnosis of COPD and in GOLD 1 stage at initial assessment were reassessed after 2 years. COPD was additionally diagnosed based on lower level of normal (LLN) lung function criteria. Utility of EBT for disease progression was analyzed using receiver operator curve (ROC) and logistic regression analyses. Change in EBT after smoking a cigarette at initial visit (ΔEBT) was significantly predictive for disease progression (newly diagnosed COPD; newly diagnosed COPD + severity progression) after 2 years (p < 0.05 for both). ΔEBT had an AUC of 0.859 (p = 0.011) with sensitivity of 66.7% and specificity of 98.1% for newly diagnosed COPD using LLN criteria. We conclude that EBT shows potential for predicting the future development of COPD in current smokers. This was best seen using LLN to diagnose COPD, adding further evidence to question the use of GOLD criteria for diagnosing COPD.

Development and the initial validation of a new self-administered questionnaire for an early detection of health status changes in smokers at risk for chronic obstructive pulmonary disease (MARKO questionnaire).

AIM: To develop and do an initial validation of a new simple tool (self-administered questionnaire) that would be sensitive and specific enough to detect early changes in smokers leading to future development of chronic obstructive pulmonary disease (COPD). METHODS: 224 consecutive participants (50.9% women), with mean±standard deviation age of 52.3±6.7 years, 37.5±16.7 pack-years smoking history (85.8% active smokers), and no prior diagnosis of COPD were recruited. The MARKO questionnaire was self-administered twice; at the general practitioner's office and after 2-4 weeks at the tertiary care hospital. Participants were assessed for COPD by a pulmonologist after filling in a quality of life (QoL) questionnaires, history-taking, physical examination, lung function test, 6-minute walk test, and laboratory tests. They were divided into four subgroups: "healthy" smokers, symptomatic smokers, and smokers with mild and moderately severe COPD. RESULTS: Psychometric analyses indicated that the 18-item questionnaire had a very good internal consistency (Cronbach's alpha=0.91) and test-retest reliability for a four week period (c=0.89, 95% confidence interval [CI] 0.85-0.92, Lin's concordance). A significant correlations of MARKO scores were found with two QoL questionnaires; r=0.69 (P<0.001) and r=0.81 (P<0.001). Receiver operating characteristic curve analysis showed an area under the curve of 0.753 (95% CI 0.691-0.808, <0.001), with a sensitivity of 71.83% and specificity of 64.24% to discriminate "healthy" smokers from other subgroups. CONCLUSION: Based on psychometric analyses and high convergent validity correlation with already validated QoL questionnaires, the newly developed MARKO questionnaire was shown to be a reliable self-administered short health status assessment tool.