Metabolic syndrome biomarkers predict lung function impairment: a nested case-control study

Challenges and Current Efforts in the Development of Biomarkers for Chronic Inflammatory and Remodeling Conditions of the Lungs

This review discusses biomarkers that are being researched for their usefulness to phenotype chronic inflammatory lung diseases that cause remodeling of the lung's architecture. The review focuses on asthma, chronic obstructive pulmonary disease (COPD), and pulmonary hypertension. Bio-markers of environmental exposure and specific classes of biomarkers (noncoding RNA, metabolism, vitamin, coagulation, and microbiome related) are also discussed. Examples of biomarkers that are in clinical use, biomarkers that are under development, and biomarkers that are still in the research phase are discussed. We chose to present examples of the research in biomarker development by diseases, because asthma, COPD, and pulmonary hypertension are distinct entities, although they clearly share processes of inflammation and remodeling.

Correlation between heart rate variability and pulmonary function adjusted by confounding factors in healthy adults

The autonomic nervous system maintains homeostasis, which is the state of balance in the body. That balance can be determined simply and noninvasively by evaluating heart rate variability (HRV). However, independently of autonomic control of the heart, HRV can be influenced by other factors, such as respiratory parameters. Little is known about the relationship between HRV and spirometric indices. In this study, our objective was to determine whether HRV correlates with spirometric indices in adults without cardiopulmonary disease, considering the main confounders (e.g., smoking and physical inactivity). In a sample of 119 asymptomatic adults (age 20-80 years), we evaluated forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). We evaluated resting HRV indices within a 5-min window in the middle of a 10-min recording period, thereafter analyzing time and frequency domains. To evaluate daily physical activity, we instructed participants to use a triaxial accelerometer for 7 days. Physical inactivity was defined as <150 min/week of moderate to intense physical activity. We found that FVC and FEV1, respectively, correlated significantly with the following aspects of the RR interval: standard deviation of the RR intervals (r =0.31 and 0.35), low-frequency component (r =0.38 and 0.40), and Poincaré plot SD2 (r =0.34 and 0.36). Multivariate regression analysis, adjusted for age, sex, smoking, physical inactivity, and cardiovascular risk, identified the SD2 and dyslipidemia as independent predictors of FVC and FEV1 (R2=0.125 and 0.180, respectively, for both). We conclude that pulmonary function is influenced by autonomic control of cardiovascular function, independently of the main confounders.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Metabolic Syndrome and the Lung

A link between metabolic syndrome (MetS) and lung diseases has been observed in several cross-sectional and longitudinal studies. This syndrome has been identified as an independent risk factor for worsening respiratory symptoms, greater lung function impairment, pulmonary hypertension, and asthma. This review will discuss several potential mechanisms to explain these associations, including dietary factors and the effect of adiposity and fat-induced inflammation on the lungs, and the role of other comorbidities that frequently coexist with MetS, such as OSA and obesity. In contrast to the well-known association between asthma and obesity, the recognition that MetS affects the lung is relatively new. Although some controversy remains as to whether MetS is a unique disease entity, its individual components have independently been associated with changes in pulmonary function or lung disease. There is, however, uncertainty as to the relative contribution that each metabolic factor has in adversely affecting the respiratory system; also, it is unclear how much of the MetS-related lung effects occur independently of obesity. In spite of these epidemiological limitations, the proposed mechanistic pathways strongly suggest that this association is likely to be causal. Given the wide prevalence of MetS in the general population, it is imperative that we continue to further understand how this metabolic disorder impacts the lung and how to prevent its complications.

Biomarkers of World Trade Center Particulate Matter Exposure: Physiology of Distal Airway and Blood Biomarkers that Predict FEV₁ Decline

Biomarkers can be important predictors of disease severity and progression. The intense exposure to particulates and other toxins from the destruction of the World Trade Center (WTC) overwhelmed the lung's normal protective barriers. The Fire Department of New York (FDNY) cohort not only had baseline pre-exposure lung function measures but also had serum samples banked soon after their WTC exposure. This well-phenotyped group of highly exposed first responders is an ideal cohort for biomarker discovery and eventual validation. Disease progression was heterogeneous in this group in that some individuals subsequently developed abnormal lung function while others recovered. Airflow obstruction predominated in WTC-exposed patients who were symptomatic. Multiple independent disease pathways may cause this abnormal FEV1 after irritant exposure. WTC exposure activates one or more of these pathways causing abnormal FEV1 in an individual. Our hypothesis was that serum biomarkers expressed within 6 months after WTC exposure reflect active disease pathways and predict subsequent development or protection from abnormal FEV1 below the lower limit of normal known as WTC-Lung Injury (WTC-LI). We utilized a nested case-cohort control design of previously healthy never smokers who sought subspecialty pulmonary evaluation to explore predictive biomarkers of WTC-LI. We have identified biomarkers of inflammation, metabolic derangement, protease/antiprotease balance, and vascular injury expressed in serum within 6 months of WTC exposure that were predictive of their FEV1 up to 7 years after their WTC exposure. Predicting future risk of airway injury after particulate exposures can focus monitoring and early treatment on a subset of patients in greatest need of these services.

Association Between Average Daily Television Viewing Time and Chronic Obstructive Pulmonary Disease-Related Mortality: Findings From the Japan Collaborative Cohort Study

Background

Sedentary behavior is associated with cardiovascular disease, diabetes mellitus, and cancer morbidity, and watching television (TV) is an important sedentary behavior. The aim of this study is to clarify the association between TV viewing time and chronic obstructive pulmonary disease (COPD)-related mortality in Japanese adults.

Methods

Using the Cox proportional hazard model, we assessed COPD-related mortality by TV viewing time in a national cohort of 33 414 men and 43 274 women without cancer, stroke, myocardial infarction, or tuberculosis at baseline (1988–1990).

Results

The median follow-up was 19.4 years; 244 men and 34 women died of COPD. Men watching ≥4 hours/day of TV were more likely to die of COPD than those watching <2 hours/day (hazard ratio 1.63; 95% confidence interval, 1.04–2.55), independent of major confounders. No association was found in women.

Conclusions

Avoiding a sedentary lifestyle, particularly prolonged TV viewing, may help in preventing death from COPD among men.

Association Between Pulmonary Function and Nonalcoholic Fatty Liver Disease in the NHANES III Study

Emerging evidence indicates that nonalcoholic fatty liver disease (NAFLD) is associated with a wide variety of extrahepatic complications. However, the potential association between impaired pulmonary function and NAFLD has been less investigated. This study examined the relationship between pulmonary function and hepatic steatosis in 9976 adults participating in a cross-sectional analysis of the Third National Health and Nutrition Examination Survey (NHANES III). NAFLD was defined as hepatic steatosis presented on ultrasound examinations in the absence of other known liver diseases. The associations between predicted forced expiratory volume in 1 second (FEV1)% or predicted forced vital capacity (FVC)% and NAFLD were examined using multivariable linear regression while controlling for confounders. The association between obstructive or restrictive spirometry patterns and NAFLD was also evaluated using multivariable logistic regression analysis. After adjustment for multiple covariates, predicted FEV1% and FVC% were significantly and inversely associated with the degree of hepatic steatosis (P for trend <0.001 for both). The restrictive lung pattern was significantly related to participants with moderate and severe hepatic steatosis as compared with those without steatosis (OR 1.65, 95% CI 1.14-2.39 and OR 1.85, 95% CI 1.13-2.82), whereas the obstructive lung pattern was not associated with the presence of hepatic steatosis. Individuals with a greater degree of hepatic steatosis were at greater risk for poor pulmonary function, especially in restrictive pattern. These novel findings demonstrate that impaired pulmonary function is also an extrahepatic complication of NAFLD.

Association of pulmonary function with adiposity and metabolic abnormalities in urban minority adolescents

RATIONALE

Childhood obesity is a known risk factor for pulmonary diseases, likely due to obesity-mediated alteration of pulmonary function. Inflammation and mechanical fat load are two proposed causative mechanisms for altered pulmonary function among obese children; however, the association of metabolic abnormalities with pulmonary function among children is poorly understood.

OBJECTIVES

We investigated the independent association of truncal and general adiposity and metabolic abnormalities with pulmonary function in a sample of urban minority adolescents.

METHODS

Spirometry and lung volume indices were compared between adolescents with general (body mass index [BMI] > 95th percentile) or truncal adiposity (waist circumference > 90th percentile) and normal-weight (BMI < 85th percentile or waist circumference ≤ 90th percentile) and between those with metabolic abnormalities (homeostatic model assessment of insulin resistance [HOMA-IR] in the top quartile or high-density lipoprotein [HDL] < 40 mg/dl) and those with a normal metabolic profile.

MEASUREMENTS AND MAIN RESULTS

Obese adolescents had lower lung volumes, including residual volume (RV), RV/TLC ratio, expiratory reserve volume (ERV), and FRC, and higher inspiratory capacity (IC) than normal-weight adolescents, but did not differ in measures of lower airway obstruction, FEV1/FVC ratio, and mid-expiratory flow rate. Adolescents with high HOMA-IR had lower FEV1/FVC ratio, RV, RV/TLC ratio, ERV, and FRC and higher IC, whereas those with low HDL had lower FEV1/FVC and RV/TLC ratios. After adjusting for adiposity, HOMA-IR remained a predictor of ERV (β = -1.4; P = 0.02) and FEV1/FVC ratio (β = -0.5; P = 0.03), and HDL remained a predictor of FEV1/FVC ratio (β = 0.1; P = 0.01). General adiposity was a predictor of FRC (β = -0.5; P < 0.001), IC (β = 0.3; P < 0.001), RV (β = -0.8; P < 0.0001), and RV/TLC ratio (β = -0.2; P < 0.0001), and truncal adiposity was a predictor of RV (β = -20.3; P = 0.03) and FRC (β = -13.8; P = 0.004). Thus, adiposity and metabolic abnormalities were independent predictors of ERV, but only metabolic abnormalities independently predicted FEV1/FVC ratio. Although general adiposity predicted RV and RV/TLC ratio, truncal adiposity was predictive of RV and FRC, conferring additional risk above general adiposity.

CONCLUSIONS

These results suggest that metabolic abnormalities and adiposity are independently associated with pulmonary function deficits among urban adolescents. Metabolic assessment of obese adolescents may identify those at risk of developing obesity-associated pulmonary morbidity.

Strategies for managing oxygenation in obese patients undergoing laparoscopic surgery

The worldwide trend toward increasing body mass index (BMI) has caused the anesthetic management of overweight, obese, and severely obese patients to become common. The increase in oxygen demand coupled with the anatomic and physiologic changes associated with excess adipose tissue make maintenance of oxygenation a major challenge during induction, maintenance and recovery from general anesthesia. It is crucial for anesthesiologists, surgeons and perioperative healthcare providers alike to have a thorough understanding of the impact of airway management and mechanical ventilation on the respiratory care of the obese in the immediate perioperative setting. In this manuscript we aim to discuss the consequences of obesity, particularly abdominal obesity, on respiratory physiology and provide suggestions on intraoperative ventilatory strategies to maintain oxygenation in the severely obese patient undergoing pneumoperitoneum.

Lung function and metabolic syndrome: Findings of National Health and Nutrition Examination Survey 2007–2010

BACKGROUND

Considerable uncertainty remains about obstructive lung function( OLF) in adults with metabolic syndrome (MetS). The aim of the present study was to examine pulmonary function status in adults with and without MetS.

METHODS

We used data from 3109 participants aged ≥20 years of the National Health and Nutrition Examination Survey 2007-2010. Subjects'MetS status was established on the basis of the 2009 harmonizing definition. Participants received spirometry.

RESULTS

After age adjustment, 79.3% (SE 1.1) of participants with MetS had normal lung function, 8.7% (0.9) had restrictive lung function (RLF), 7.1% (0.8) had mild OLF, and 4.8% (0.6) had moderate OLF or worse. Among participants without MetS, these estimates were 78.7% (1.2), 3.9% (0.6), 10.9%(1.1), and 6.4% (0.8), respectively. After multiple adjustment, participants with MetS were more likely to have RLF (adjusted prevalence ratio [aPR] 2.20; 95% confidence interval [CI] 1.67, 2.90) and less likely to have any OLF (aPR 0.73; 95% CI 0.62, 0.86) than those without MetS. Furthermore, participants with MetS had lower mean levels of forced expiratory volume in one second (FEV1), FEV1 % predicted, forced vital capacity (FVC), and FVC % predicted, but a higher FEV1/FVC ratio than participants without MetS. Mean levels of FEV1, FEV1 % predicted, FVC, and FVC % predicted declined significantly, but not the FEV1/FVC ratio, as the number of components increased.

CONCLUSIONS

Compared with adults without MetS, spirometry is more likely to show a restrictive pattern and less likely to show an obstructive pattern among adults with MetS.

Enlarged pulmonary artery is predicted by vascular injury biomarkers and is associated with WTC-Lung Injury in exposed fire fighters: a case-control study

OBJECTIVES

We hypothesise that there is an association between an elevated pulmonary artery/aorta (PA/A) and World Trade Center-Lung Injury (WTC-LI). We assessed if serum vascular disease biomarkers were predictive of an elevated PA/A.

DESIGN

Retrospective case-cohort analysis of thoracic CT scans of WTC-exposed firefighters who were symptomatic between 9/12/2001 and 3/10/2008. Quantification of vascular-associated biomarkers from serum collected within 200 days of exposure.

SETTING

Urban tertiary care centre and occupational healthcare centre.

PARTICIPANTS

Male never-smoking firefighters with accurate pre-9/11 forced expiratory volume in 1 s (FEV1)≥75%, serum sampled ≤200 days of exposure was the baseline cohort (n=801). A subcohort (n=97) with available CT scans and serum biomarkers was identified. WTC-LI was defined as FEV1≤77% at the subspecialty pulmonary evaluation (n=34) and compared with controls (n=63) to determine the associated PA/A ratio. The subcohort was restratified based on PA/A≥0.92 (n=38) and PA/A<0.92(n=59) to determine serum vascular biomarkers that were predictive of this vasculopathy.

OUTCOME MEASURES

The primary outcome of this study was to identify a PA/A ratio in a cohort of individuals exposed to WTC dust that was associated with WTC-LI. The secondary outcome was to identify serum biomarkers predictive of the PA/A ratio using logistic regression.

RESULTS

PA/A≥0.92 was associated with WTC-LI, OR of 4.02 (95% CI 1.21 to 13.41; p=0.023) when adjusted for exposure, body mass index and age at CT. Elevated macrophage derived chemokine and soluble endothelial selectin were predictive of PA/A≥0.92, (OR, 95% CI 2.08, 1.05 to 4.11, p=0.036; 1.33, 1.06 to 1.68, p=0.016, respectively), while the increased total plasminogen activator inhibitor 1 was predictive of not having PA/A≥0.92 (OR 0.88, 0.79 to 0.98; p=0.024).

CONCLUSIONS

Elevated PA/A was associated with WTC-LI. Development of an elevated PA/A was predicted by biomarkers of vascular disease found in serum drawn within 6 months of WTC exposure. Increased PA/A is a potentially useful non-invasive biomarker of WTC-LI and warrants further study.

Lysophosphatidic acid and apolipoprotein A1 predict increased risk of developing World Trade Center-lung injury: a nested case-control study

RATIONALE

Metabolic syndrome, inflammatory and vascular injury markers measured in serum after World Trade Center (WTC) exposures predict abnormal FEV1. We hypothesized that elevated LPA levels predict FEV₁ < LLN.

METHODS

Nested case-control study of WTC-exposed firefighters. Cases had FEV₁ < LLN. Controls derived from the baseline cohort. Demographics, pulmonary function, serum lipids, LPA and ApoA1 were measured.

RESULTS

LPA and ApoA1 levels were higher in cases than controls and predictive of case status. LPA increased the odds by 13% while ApoA1 increased the odds by 29% of an FEV₁ < LLN in a multivariable model.

CONCLUSIONS

Elevated LPA and ApoA1 are predictive of a significantly increased risk of developing an FEV₁ < LLN.

MMP-2 and TIMP-1 predict healing of WTC-lung injury in New York City firefighters

Rationale

After 9/11/2001, most FDNY workers had persistent lung function decline but some exposed workers recovered. We hypothesized that the protease/anti-protease balance in serum soon after exposure predicts subsequent recovery.

Methods

We performed a nested case–control study measuring biomarkers in serum drawn before 3/2002 and subsequent forced expiratory volume at one second (FEV₁) on repeat spirometry before 3/2008. Serum was assayed for matrix metalloproteinases (MMP-1,2,3,7,8,9,12 and 13) and tissue inhibitors of metalloproteinases (TIMP-1,2,3,4). The representative sub-cohort defined analyte distribution and a concentration above 75^th percentile defined elevated biomarker expression. An FEV₁ one standard deviation above the mean defined resistance to airway injury. Logistic regression was adjusted for pre-9/11 FEV₁, BMI, age and exposure intensity modeled the association between elevated biomarker expression and above average FEV₁.

Results

FEV₁ in cases and controls declined 10% of after 9/11/2001. Cases subsequently returned to 99% of their pre-exposure FEV₁ while decline persisted in controls. Elevated TIMP-1 and MMP-2 increased the odds of resistance by 5.4 and 4.2 fold while elevated MMP-1 decreased it by 0.27 fold.

Conclusions

Resistant cases displayed healing, returning to 99% of pre-exposure values. High TIMP-1 and MMP-2 predict healing. MMP/TIMP balance reflects independent pathways to airway injury and repair after WTC exposure.

YKL-40 is a Protective Biomarker for Fatty Liver in World Trade Center Particulate Matter-Exposed Firefighters

Background

Serum biomarkers of metabolic syndrome predict abnormal lung function in World Trade Center particulate matter (WTC-PM)-exposed Fire Department of New York (FDNY) rescue workers. In animal models, exposure to ambient PM induces non-alcoholic fatty liver disease (NAFLD), a well-known comorbidity of metabolic syndrome. YKL-40 is an inflammatory biomarker for both liver and lung disease. We tested if YKL-40 is a biomarker for NAFLD in this dust-exposed cohort.

Methods

Using a nested case-control design, we studied 131 FDNY personnel who had Computer Tomography performed within 5 years post 9/11. NAFLD was defined by a liver/spleen attenuation ratio of ≤1. Serum biomarkers, lipid panel and liver function were measured in serum that had been drawn within 6 months of September 11, 2001. YKL-40 and chitotriosidase were assayed by ELISA. We tested biomarker and NAFLD association using logistic regression adjusted for age, BMI, and post-911 lung function.

Results

NAFLD was present in 29/131 (22%) of the cohort. In a multivariable model increasing YKL-40 was protective while increasing triglyceride and alkaline phosphatase were risk factors for NAFLD.

Conclusions

Increased YKL-40 is a protective biomarker in non-alcoholic fatty liver disease. Further studies may reveal a link between PM-induced lung and liver diseases.

One airway: Biomarkers of protection from upper and lower airway injury after World Trade Center exposure

BACKGROUND

Firefighters exposed to World Trade Center (WTC) dust have developed chronic rhinosinusitis (CRS) and abnormal forced expiratory volume in 1 s (FEV1). Overlapping but distinct immune responses may be responsible for the clinical manifestations of upper and lower airway injury. We investigated whether a panel of inflammatory cytokines, either associated or not associated with WTC-LI, can predict future chronic rhinosinusitis disease and its severity.

METHODS

Serum obtained within six months of 9/11/2001 from 179 WTC exposed firefighters presenting for subspecialty evaluation prior to 3/2008 was assayed for 39 cytokines. The main outcomes were medically managed CRS (N = 62) and more severe CRS cases requiring sinus surgery (N = 14). We tested biomarker-CRS severity association using ordinal logistic regression analysis.

RESULTS

Increasing serum IL-6, IL-8, GRO and neutrophil concentration reduced the risk of CRS progression. Conversely, increasing TNF-α increased the risk of progression. In a multivariable model adjusted for exposure intensity, increasing IL-6, TNF-α and neutrophil concentration remained significant predictors of progression. Elevated IL-6 levels and neutrophil counts also reduced the risk of abnormal FEV1 but in contrast to CRS, increased TNF-α did not increase the risk of abnormal FEV1.

CONCLUSIONS

Our study demonstrates both independent and overlapping biomarker associations with upper and lower respiratory injury, and suggests that the innate immune response may play a protective role against CRS and abnormal lung function in those with WTC exposure.

Early elevation of serum MMP-3 and MMP-12 predicts protection from World Trade Center-lung injury in New York City Firefighters: a nested case-control study

Objective

After 9/11/2001, some Fire Department of New York (FDNY) workers had excessive lung function decline. We hypothesized that early serum matrix metalloproteinases (MMP) expression predicts World Trade Center-Lung Injury (WTC-LI) years later.

Methods

This is a nested case-control analysis of never-smoking male firefighters with normal pre-exposure Forced Expiratory Volume in one second (FEV₁) who had serum drawn up to 155 days post 9/11/2001. Serum MMP-1, 2,3,7,8, 9, 12 and 13 were measured. Cases of WTC-LI (N = 70) were defined as having an FEV1 one standard deviation below the mean (FEV₁≤77%) at subspecialty pulmonary evaluation (SPE) which was performed 32 months (IQR 21–53) post-9/11. Controls (N = 123) were randomly selected. We modeled MMP's ability as a predictor of cases status with logistic regression adjusted for time to blood draw, exposure intensity, weight gain and pre-9/11 FEV₁.

Results

Each log-increase in MMP-3 and MMP-12 showed reduced odds of developing WTC-LI by 73% and 54% respectively. MMP-3 and MMP-12 consistently clustered together in cases, controls, and the cohort. Increasing time to blood draw significantly and independently increased the risk of WTC-LI.

Conclusions

Elevated serum levels of MMP-3 and MMP-12 reduce the risk of developing WTC-LI. At any level of MMP-3 or 12, increased time to blood draw is associated with a diminished protective effect.

Adiponectin: an attractive marker for metabolic disorders in Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory lung disease which may be complicated by development of co-morbidities including metabolic disorders. Metabolic disorders commonly associated with this disease contribute to lung function impairment and mortality. Systemic inflammation appears to be a major factor linking COPD to metabolic alterations. Adipose tissue seems to interfere with systemic inflammation in COPD patients by producing a large number of proteins, known as “adipokines”, involved in various processes such as metabolism, immunity and inflammation. There is evidence that adiponectin is an important modulator of inflammatory processes implicated in airway pathophysiology. Increased serum levels of adiponectin and expression of its receptors on lung tissues of COPD patients have recently highlighted the importance of the adiponectin pathway in this disease. Further, in vitro studies have demonstrated an anti-inflammatory activity for this adipokine at the level of lung epithelium. This review focuses on mechanisms by which adiponectin is implicated in linking COPD with metabolic disorders.

Chitotriosidase is a biomarker for the resistance to World Trade Center lung injury in New York City firefighters

PURPOSE

World Trade Center (WTC) exposure caused airflow obstruction years after exposure. Chitinases and IgE are innate and humoral mediators of obstructive airway disease. We investigated if serum expression of chitinases and IgE early after WTC exposure predicts subsequent obstruction.

METHODS

With a nested case-control design, 251 FDNY personnel had chitotriosidase, YKL-40 and IgE measured in serum drawn within months of 9/11/2001. The main outcome was subsequent Forced Expiratory Volume after 1 second/Forced Vital Capacity (FEV1/FVC) less than the lower limit of normal (LLN). Cases (N = 125) had abnormal FEV1/FVC whereas controls had normal FEV1/FVC (N = 126). In a secondary analysis, resistant cases (N = 66) had FEV1 (≥107%) one standard deviation above the mean. Logistic regression adjusted for age, BMI, exposure intensity and post-exposure FEV1/FVC modeled the association between early biomarkers and later lung function.

RESULTS

Cases and Controls initially lost lung function. Controls recovered to pre-9/11 FEV1 and FVC while cases continue to decline. Cases expressed lower serum chitotriosidase and higher IgE levels. Increase in IgE increased the odds of airflow obstruction and decreased the odds of above average FEV1. Alternately, increasing chitotriosidase decreased the odds of abnormal FEV1/FVC and increased the odds of FEV1 ≥ 107%. Serum YKL-40 was not associated with FEV1/FVC or FEV1 in this cohort.

CONCLUSIONS

Increased serum chitotriosidase reduces the odds of developing obstruction after WTC-particulate matter exposure and is associated with recovery of lung function. Alternately, elevated IgE is a risk factor for airflow obstruction and progressive lung function decline.

Cigarette smoke decreases airway epithelial FABP5 expression and promotes Pseudomonas aeruginosa infection

Cigarette smoking is the primary cause of Chronic Obstructive Pulmonary Disease (COPD), which is characterized by chronic inflammation of the airways and destruction of lung parenchyma. Repeated and sustained bacterial infections are clearly linked to disease pathogenesis (e.g., exacerbations) and a huge burden on health care costs. The airway epithelium constitutes the first line of host defense against infection and our previous study indicated that Fatty Acid Binding Protein 5 (FABP5) is down regulated in airway epithelial cells of smokers with COPD as compared to smokers without COPD. We hypothesized that cigarette smoke (CS) exposure down regulates FABP5, thus, contributing to a more sustained inflammation in response to bacterial infection. In this report, we show that FABP5 is increased following bacterial infection but decreased following CS exposure of primary normal human bronchial epithelial (NHBE) cells. The goal of this study was to address FABP5 function by knocking down or overexpressing FABP5 in primary NHBE cells exposed to CS. Our data indicate that FABP5 down regulation results in increased P. aeruginosa bacterial load and inflammatory cytokine levels (e.g., IL-8) and decreased expression of the anti-bacterial peptide, β defensin-2. On the contrary, FABP5 overexpression exerts a protective function in airway epithelial cells against P. aeruginosa infection by limiting the production of IL-8 and increasing the expression of β defensin-2. Our study indicates that FABP5 exerts immunomodulatory functions in the airway epithelium against CS exposure and subsequent bacterial infection through its modulation of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ activity. These findings support the development of FABP5/PPAR-γ-targeted therapeutic approach to prevent airway inflammation by restoring antimicrobial immunity during COPD exacerbations.

Systemic inflammation and lung function impairment in morbidly obese subjects with the metabolic syndrome

BACKGROUND

Obesity and asthma are associated. There is a relationship between lung function impairment and the metabolic syndrome. Whether this relationship also exists in the morbidly obese patients is still unknown. Hypothesis. Low-grade systemic inflammation associated with the metabolic syndrome causes inflammation in the lungs and, hence, lung function impairment.

METHODS

This is cross-sectional study of morbidly obese patients undergoing preoperative screening for bariatric surgery. Metabolic syndrome was assessed according to the revised NCEP-ATP III criteria.

RESULTS

A total of 452 patients were included. Patients with the metabolic syndrome (n = 293) had significantly higher blood monocyte (mean 5.3 versus 4.9, P = 0.044) and eosinophil percentages (median 1.0 versus 0.8, P = 0.002), while the total leukocyte count did not differ between the groups. The FEV1/FVC ratio was significantly lower in patients with the metabolic syndrome (76.7% versus 78.2%, P = 0.032). Blood eosinophils were associated with FEV1/FVC ratio (adj. B -0.113, P = 0.018).

CONCLUSION

Although the difference in FEV1/FVC ratio between the groups is relatively small, in this cross-sectional study, and its clinical relevance may be limited, these data indicate that the presence of the metabolic syndrome may influence lung function impairment, through the induction of relative eosinophilia.

Cardiovascular biomarkers predict susceptibility to lung injury in World Trade Center dust-exposed firefighters

Pulmonary vascular loss is an early feature of chronic obstructive pulmonary disease. Biomarkers of inflammation and of metabolic syndrome predict loss of lung function in World Trade Center (WTC) lung injury (LI). We investigated if other cardiovascular disease (CVD) biomarkers also predicted WTC-LI. This nested case-cohort study used 801 never-smoker, WTC-exposed firefighters with normal pre-9/11 lung function presenting for subspecialty pulmonary evaluation (SPE) before March 2008. A representative subcohort of 124 out of 801 subjects with serum drawn within 6 months of 9/11 defined CVD biomarker distribution. Post-9/11 forced expiratory volume in 1 s (FEV1) at defined cases were as follows: susceptible WTC-LI cases with FEV1 ≤77% predicted (66 out of 801) and resistant WTC-LI cases with FEV1 ≥107% predicted (68 out of 801). All models were adjusted for WTC exposure intensity, body mass index at SPE, age on 9/11 and pre-9/11 FEV1. Susceptible WTC-LI cases had higher levels of apolipoprotein-AII, C-reactive protein and macrophage inflammatory protein-4 with significant relative risks (RRs) of 3.85, 3.93 and 0.26, respectively, with an area under the curve (AUC) of 0.858. Resistant WTC-LI cases had significantly higher soluble vascular cell adhesion molecule and lower myeloperoxidase, with RRs of 2.24 and 2.89, respectively (AUC 0.830). Biomarkers of CVD in serum 6 months post-9/11 predicted either susceptibility or resistance to WTC-LI. These biomarkers may define pathways either producing or protecting subjects from pulmonary vascular disease and associated loss of lung function after an irritant exposure.

Comparison of WTC dust size on macrophage inflammatory cytokine release in vivo and in vitro

Background

The WTC collapse exposed over 300,000 people to high concentrations of WTC-PM; particulates up to ∼50 mm were recovered from rescue workers’ lungs. Elevated MDC and GM-CSF independently predicted subsequent lung injury in WTC-PM-exposed workers. Our hypotheses are that components of WTC dust strongly induce GM-CSF and MDC in AM; and that these two risk factors are in separate inflammatory pathways.

Methodology/Principal Findings

Normal adherent AM from 15 subjects without WTC-exposure were incubated in media alone, LPS 40 ng/mL, or suspensions of WTC-PM_10–53 or WTC-PM_2.5 at concentrations of 10, 50 or 100 µg/mL for 24 hours; supernatants assayed for 39 chemokines/cytokines. In addition, sera from WTC-exposed subjects who developed lung injury were assayed for the same cytokines. In the in vitro studies, cytokines formed two clusters with GM-CSF and MDC as a result of PM_10–53 and PM_2.5. GM-CSF clustered with IL-6 and IL-12(p70) at baseline, after exposure to WTC-PM_10–53 and in sera of WTC dust-exposed subjects (n = 70) with WTC lung injury. Similarly, MDC clustered with GRO and MCP-1. WTC-PM_10–53 consistently induced more cytokine release than WTC-PM_2.5 at 100 µg/mL. Individual baseline expression correlated with WTC-PM-induced GM-CSF and MDC.

Conclusions

WTC-PM_10–53 induced a stronger inflammatory response by human AM than WTC-PM_2.5. This large particle exposure may have contributed to the high incidence of lung injury in those exposed to particles at the WTC site. GM-CSF and MDC consistently cluster separately, suggesting a role for differential cytokine release in WTC-PM injury. Subject-specific response to WTC-PM may underlie individual susceptibility to lung injury after irritant dust exposure.