Enhancing effect of dietary cholesterol and inhibitory effect of pravastatin on allergic pulmonary inflammation

Protective effects of statins on pulmonary function in patients with persistent hyperlipidemia: a retrospective cohort study

BACKGROUND

Pulmonary function tests offer crucial parameters for evaluating lung health and predicting clinical outcomes. Hyperlipidemia, a prevalent metabolic disorder, has been linked to declining pulmonary function. Statins are an essential therapy for lowering lipid levels in hyperlipidemia.

OBJECTIVES

This study aims to investigate the therapeutic potential of statins in mitigating the decline in pulmonary function.

DESIGN

This is a retrospective cohort study.

METHODS

Out of 8286 patients who underwent spirometry testing from January 2018 to December 2020, 492 patients were included in the final analysis. The relationship between statin usage, dosage, along with other biometric indices and spirometry parameters were evaluated. Multivariate logistic regression analyses were employed to assess the association between statin use and the decline in pulmonary function.

RESULTS

In patients with persistent hyperlipidemia, the use of statins was associated with a higher predicted percentage of forced expiratory volume in 1 second (FEV1) compared to non-users (84.0% vs 78.0%, p = 0.015). Logistic regression models further revealed that statin use independently prevented FEV1 decline, irrespective of dosage (adjusted OR 0.036, 95% CI: 0.002-0.618 in lower statins dose group and adjusted OR 0.170, 95% CI: 0.019-1.552 in higher statins dose group).

CONCLUSION

The findings suggested that statin usage, regardless of dosage, independently mitigated the decline in pulmonary function among patients with persistent hyperlipidemia. Early initiation of statin therapy may hold promise for individuals experiencing hyperlipidemia and declining pulmonary function.

Real-World Effectiveness of Statin Therapy in Adult Asthma

BACKGROUND

Blood lipids affect airway inflammation in asthma. Although several studies have suggested anti-inflammatory effects of statins on asthmatic airways, further studies are needed to clarify the long-term effectiveness of statins on asthma control and whether they are an effective treatment option.

OBJECTIVE

To evaluate the long-term effectiveness of statins in the chronic management of adult asthma in real-world practice.

METHODS

Electronic medical record data spanning 28 years, collected from the Ajou University Medical Center in Korea, were used to conduct a retrospective study. Clinical outcomes were compared between patients with asthma who had maintained statin use (the statin group) and those not taking statins, whose blood lipid tests were always normal (the non-statin group). We performed propensity score matching and calculated hazard ratios with 95% CIs using the Cox proportional hazards model. Severe asthma exacerbation was the primary outcome; asthma exacerbation, asthma-related hospitalization, and new-onset type 2 diabetes mellitus and hypertension were secondary outcomes.

RESULTS

After 1:1 propensity score matching, the statin and non-statin groups each included 545 adult patients with asthma. The risk of severe asthma exacerbations and asthma exacerbations was significantly lower in the statin group than in the non-statin group (hazard ratios [95% CI] = 0.57 [0.35-0.90] and 0.71 [0.52-0.96], respectively). There were no significant differences in the risk of asthma-related hospitalization or new-onset type 2 diabetes mellitus or hypertension between groups (0.76 [0.53-1.09], 2.33 [0.94-6.59], and 1.71 [0.95-3.17], respectively).

CONCLUSION

Statin use is associated with a lower risk of asthma exacerbation, with better clinical outcomes in adult asthma.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

Sterols and immune mechanisms in asthma

The field of sterol and oxysterol biology in lung disease has recently gained attention, revealing a unique need for sterol uptake and metabolism in the lung. The presence of cholesterol transport, biosynthesis, and sterol/oxysterol-mediated signaling in immune cells suggests a role in immune regulation. In support of this idea, statin drugs that inhibit the cholesterol biosynthesis rate-limiting step enzyme, hydroxymethyl glutaryl coenzyme A reductase, show immunomodulatory activity in several models of inflammation. Studies in human asthma reveal contradicting results, whereas promising retrospective studies suggest benefits of statins in severe asthma. Here, we provide a timely review by discussing the role of sterols in immune responses in asthma, analytical tools to evaluate the role of sterols in disease, and potential mechanistic pathways and targets relevant to asthma. Our review reveals the importance of sterols in immune processes and highlights the need for further research to solve critical gaps in the field.

Depression in Childhood Asthma vs. Adult-Onset Asthma: A Cross-Sectional Study from the National Health and Nutrition Examination Survey (NHANES)

Background: asthma, a chronic respiratory disease caused by inflammation and narrowing of the small airways in the lungs, is the most common chronic childhood disease. Prevalence of childhood asthma in the United States is 5.8%. In boys, prevalence is 5.7% and it is 6% in girls. Asthma is associated with other comorbidities such as major depressive disorder and anxiety disorder. This study explores the association between asthma and depression. Methods: we conducted a retrospective cross-sectional study using NHANES data from 2013 to 2018. Asthma and childhood onset asthma were assessed using questionnaires MCQ010 and MCQ025, respectively. Sociodemographic variables were summarized, and univariate analysis was performed to determine the association between asthma and major depressive disorder and its individual symptoms. Results: there were 402,167 participants from 2013−2018 in our study: no asthma in 84.70%; asthma in 15.30%. Childhood onset asthma (COA) included 10.51% and adult-onset asthma (AOA) included 4.79%. Median age of COA is 5 years and AOA is 41 years. Among the asthma groups, most AOA were females (67.77%, p < 0.0001), most COA were males (52.16%, p < 0.0001), and ethnicity was predominantly White in AOA (42.39%, p < 0001) and in COA (35.24%, p < 0.0001). AOA mostly had annual household income from $0−24,999 (35.91%, p < 0.0001), while COA mostly had annual household income from $25,000−64,999 (36.66%, p < 0.0001). There was a significantly higher prevalence of MDD in COA (38.90%) and AOA (47.30%) compared to NOA (31.91%). Frequency of symptoms related to MDD were found to have a significantly higher prevalence and severity in the asthma groups compared to no asthma, and slightly greater and more severe in AOA than in COA. Symptoms include having little interest in doing things (COA 18.38% vs. AOA 22.50% vs. NOA 15.44%), feeling down, depressed, or hopeless (COA 20.05% vs. AOA 22.77% vs. NOA 15.85%), having trouble sleeping or sleeping too much (COA 27.38% vs. AOA 23.15% vs. NOA 22.24%), feeling tired or having little energy (COA 39.17% vs. AOA 34.24% vs. NOA 33.97%), having poor appetite or overeating (COA 19.88% vs. AOA 20.02% vs. NOA 15.11%), feeling bad about yourself (COA 13.90% vs. AOA 13.79% vs. NOA 10.78%), having trouble concentrating on things (COA 12.34% vs. AOA 14.41% vs. NOA 10.06%), moving or speaking slowly or too fast (COA 8.59% vs. AOA 9.72% vs. NOA 6.09%), thinking you would be better off dead (COA 3.12% vs. AOA 4.38% vs. NOA 1.95%) and having the difficulties these problems have caused (COA 21.66% vs. AOA 26.73% vs. NOA 19.34%, p < 0.0001). Conclusion: MDD and related symptoms were significantly higher and more severe in participants with asthma compared to no asthma. Between adult-onset asthma compared to childhood onset asthma, adult-onset asthma had slightly greater and more severe MDD and related symptoms compared to childhood onset asthma.

High density lipoprotein inhibited group II innate lymphoid cells proliferation and function in allergic rhinitis

Background

More and more studies had suggested that dyslipidemia was closely related to allergic diseases. High density lipoprotein (HDL) often plays anti-inflammatory and anti-oxidative roles by suppressing immune cell chemotaxis and activation. We aimed to explore the role of HDL in the regulation of group II innate lymphoid cells (ILC2) in allergic rhinitis (AR).

Methods

The blood lipid levels and their correlation with symptom scores of 20 AR subjects and 20 controls were analyzed. Purified ILC2 were stimulated by HDL and cytokines production were examined by enzyme-linked immunosorbent assay (ELISA) and flow cytometry. The mRNA levels of GATA binding protein 3(GATA3) and retinoid-related orphan receptor α (RORα) expressed by ILC2 were detected using reverse transcription polymerase chain reaction (RT-PCR).

Results

HDL level was significantly lower in AR than controls and correlated with the symptom scores. The serum HDL levels were negatively related to the increased number of ILC2, IL-5⁺ ILC2, and IL-13⁺ ILC2 in AR patients. HDL decreased the number of ILC2 and type II cytokines levels significantly by inhibiting expression of GATA3 and RORα.

Conclusions

Our data provide preliminary evidence that HDL may play a negative role in ILC2 inflammation in AR, suggesting that HDL may serve as promising treatment target in AR.

The association between serum apolipoprotein B and fractional exhaled nitric oxide in bronchial asthma patients

Background

Asthma and lipid metabolism are associated with systemic inflammation. However, the studies about the relationship between lipid profile, fractional exhaled nitric acid (FeNO) and pulmonary function test (PFT) results are currently lacking.

Methods

We enrolled asthma patients who had serum lipid profiles including apolipoprotein levels from March 1, 2019 to December 31, 2019. We classified the asthma patients into two groups according to the diagnosis method: (I) patients who were diagnosed based on clinical symptoms/signs and PFT results and (II) patients diagnosed with clinical symptoms/signs. Clinical characteristics including age, underlying diseases, smoking status, allergy test results and treatment agents were compared between the two groups. The associations between blood cholesterol levels including apolipoprotein and pulmonary functions were analyzed. Moreover, patients were divided into two groups according to the median value of apolipoprotein B (Apo B), and lung function test results were compared between the patients who had high and low Apo B levels.

Results

Among the 167 patients, 93 (55.7%) were PFT-proven asthma patients. In PFT-proven asthma patients, the levels of total cholesterol (TC) (r =0.37, P=0.03), low-density lipoprotein (LDL) (r =0.46, P=0.01) and Apo B (r =0.38, P=0.02) showed a significant correlation with FeNO, which had no statistical significance in physician-diagnosed asthma group. In multivariate regression analysis, log (FeNO) showed a significant correlation with Apo B (P<0.01) after adjustment for presence of PFT-proven asthma (P=0.01) and current smoking (P=0.01). Patients with high Apo B levels had a lower post-bronchodilator (BD) forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio (69.8 vs. 74.9, P=0.02) and lower post-BD FEV1 (%) (77.5 vs. 85.0, P=0.04) compared with those showing low Apo B levels.

Conclusions

The levels of Apo B and FeNO had positive correlations and high Apo B levels were associated with severe airflow obstruction and low FEV1 (%). Apo B could reflect the uncontrolled status of bronchial asthma and poor lung function.

Effect of Lavandula dentata extract on Ovalbumin-induced Asthma in Male Guinea Pigs

Asthma is an inflammatory disease of the lungs, and it causes oxidative stress. Lavandula dentata is an aromatic herb with anti-oxidative and anti-inflammatory activities. This study examined the activity of L. dentata extract on a guinea pig model of asthma. Adult males were divided into five groups: First group was control, second was asthma model induced by OVA, third was treated with L. dentata extract orally (300 mg/kg) for 21 days; the fourth was an asthma model with L. dentata extract (300 mg/kg) and fifth was treated with Tween 80 for 21 days. OVA treatment increased IgE, triglycerides, total cholesterol, glucose levels in serum, WBC count in blood and MDA in lungs. Also, OVA reduced SOD activity, GSH content in lungs, and GGT activity in serum (p<0.05). L. dentata extract treatment in asthma model reduced elevated IgE, triglycerides, total cholesterol, glucose levels in serum, and MDA in lungs (p<0.05), while it increased GSH content in lungs (p<0.05). These results suggest the possibility that L . dentata extract can exert suppressive effects on asthma, and may provide evidence that it is a useful agent for the treatment of allergic airway disease, it also limits oxidative stress induced by OVA. L. dentata extract appears to have hypolipidemic and hypoglycemic activities.

Rosuvastatin suppresses cytokine production and lung inflammation in asthmatic, hyperlipidemic and asthmatic-hyperlipidemic rat models

BACKGROUND

Given the role that T lymphocytes play on the pathogenesis of allergic asthma, drugs targeting Th2 and Th17 cells may be a hopeful therapeutic strategy. This study aimed to evaluate the effect of rosuvastatin treatment on cytokine production and lung inflammation in allergic asthma.

METHODS

The animals were assigned into control (C), asthmatic (A), hyperlipidemic (H), asthmatic-hyperlipidemic (AH), rosuvastatin (40 mg/kg/day intraperitoneally, for 3 weeks)-treated asthmatic (AR), rosuvastatin-treated hyperlipidemic (HR) and rosuvastatin-treated asthmatic-hyperlipidemic (AHR) groups (n = 6 in each group). The levels of IL-4, IFN-γ and IL-17, total and differential WBC counts in bronchoalveolar lavage fluid (BALF), Th1/Th2 balance, and pathological changes were evaluated.

RESULTS

The BALF level of IL-4 in A, H and AH groups, and IL-17A in A and AH groups were significantly higher than that in C group (p < 0.05 to p < 0.001). IFN-γ level and Th1/Th2 balance (IFN‑γ/IL-4 ratio) in A and AH groups were significantly decreased (p < 0.05 to p < 0.01). Inflammatory cells infiltration, muscle hypertrophy and emphysema were also observed in A and AH groups. The BALF levels of IL-4 in AR, HR and AHR groups, IFN-γ level in HR group, and IL-17A level in AR and AHR groups showed a significant improvement compared to that of A, H and AH groups (p < 0.05 to p < 0.001). Rosuvastatin treatment increased Th1/Th2 balance in all treated groups (p < 0.05 to p < 0.01), decreased total WBC counts, neutrophilia, eosinophilia and lung inflammation in AR and AHR groups, and improved muscle hypertrophy and emphysema in AHR group.

CONCLUSIONS

Rosuvastatin treatment improved lung pathological changes by suppression of Th2 and Th17-mediated cytokines which was unrelated to its lipid-lowering activity. Therefore, rosuvastatin might be a candidate immunomodulatory drug for treatment of patients with allergic asthma.

Adherence to the Mediterranean diet and inflammatory markers in children with asthma

INTRODUCTION

There is accumulated evidence supporting a beneficial role of Mediterranean diet (MD) in the control of asthma symptoms. The aim of this study was to investigate the relationships between adherence to MD and serum levels of certain cytokines namely, interleukin (IL)-4, and IL-17 known to have a pathogenetic role in the airway changes associated with asthma.

METHODS

We measured serum IL-4, IL-33, and IL-17, in 44 asthmatic and 26 healthy children, 5-15 years old. Their adherence to MD was estimated with the Mediterranean Diet Quality Index for children and adolescents (KIDMED) score.

RESULTS

KIDMED score did not differ between the two groups (P=0.59) and was not correlated with any of the three measured cytokines. However, when the analysis was restricted only to asthmatic children, the KIDMED score was correlated with IL-4, IL-33, and IL-17 (Beta: -0.56, P=0.007; Beta: 0.57, P=0.010; Beta: -0.62, P=0.017, respectively).

CONCLUSION

Our results indicate that MD can modulate the production of some of the main inflammatory mediators of asthma, in asthmatic children.

Transcriptomic Sequencing of Airway Epithelial Cell NCI-H292 Induced by Synthetic Cationic Polypeptides

Eosinophil asthma is characterized by the infiltration of eosinophils to the bronchial epithelium. The toxic cationic protein released by eosinophils, mainly major basic protein (MBP), is one of the most important causative factors of epithelium damage. Poly-L-Arginine (PLA) is a kind of synthetic cationic polypeptides, which is widely used to mimic the effects of MBP on epithelial cells in vitro. However, little is known about the changes of differentially expressed genes (DEGs) and transcriptome profiles in cationic protein stimulated epithelial cells. In this study, we compared the expression of DEGs and transcriptome profiles between PLA-treated airway epithelial cells NCI-H292 and control. The results showed that there were a total of 230 DEGs, of which 86 were upregulated and 144 were downregulated. These DEGs were further analyzed using gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results showed that the upregulated DEGs were involved in cholesterol synthesis, protein binding, and composition of cellular membranes, mainly enriched in metabolic and biosynthesis pathways. While downregulated DEGs were implicated in cell adhesion, extracellular matrix (ECM) composition and cytoskeleton and were enriched in ECM pathway. In conclusion, our research provided the mechanism of the cationic polypeptides acting on the airway epithelial cells on the basis of transcriptomic profile, and this could be regarded as important indications in unveiling the pathologic role of natural cationic proteins in the damage to epithelial cells of asthmatics.

Repurposing of statins via inhalation to treat lung inflammatory conditions

Despite many therapeutic advancements over the past decade, the continued rise in chronic inflammatory lung diseases incidence has driven the need to identify and develop new therapeutic strategies, with superior efficacy to treat these diseases. Statins are one class of drug that could potentially be repurposed as an alternative treatment for chronic lung diseases. They are currently used to treat hypercholesterolemia by inhibiting the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, that catalyses the rate limiting step in the mevalonate biosynthesis pathway, a key intermediate in cholesterol metabolism. Recent research has identified statins to have other protective pleiotropic properties including anti-inflammatory, anti-oxidant, muco-inhibitory effects that may be beneficial for the treatment of chronic inflammatory lung diseases. However, clinical studies have yielded conflicting results. This review will summarise some of the current evidences for statins pleiotropic effects that could be applied for the treatment of chronic inflammatory lung diseases, their mechanisms of actions, and the potential to repurpose statins as an inhaled therapy, including a detailed discussion on their different physical-chemical properties and how these characteristics could ultimately affect treatment efficacies. The repurposing of statins from conventional anti-cholesterol oral therapy to inhaled anti-inflammatory formulation is promising, as it provides direct delivery to the airways, reduced risk of side effects, increased bioavailability and tailored physical-chemical properties for enhanced efficacy.

A New Frontier in Immunometabolism. Cholesterol in Lung Health and Disease

The lung has a unique relationship to cholesterol that is shaped by its singular physiology. On the one hand, the lungs receive the full cardiac output and have a predominant dependence on plasma lipoprotein uptake for their cholesterol supply. On the other hand, surfactant lipids, including cholesterol, are continually susceptible to oxidation owing to direct environmental exposure and must be cleared or recycled because of the very narrow biophysical mandates placed upon surfactant lipid composition. Interestingly, increased lipid-laden macrophage "foam cells" have been noted in a wide range of human lung pathologies. This suggests that lipid dysregulation may be a unifying and perhaps contributory event in chronic lung disease pathogenesis. Recent studies have shown that perturbations in intracellular cholesterol trafficking critically modify the immune response of macrophages and other cells. This minireview discusses literature that has begun to demonstrate the importance of regulated cholesterol traffic through the lung to pulmonary immunity, inflammation, and fibrosis. This emerging recognition of coupling between immunity and lipid homeostasis in the lung presents potentially transformative concepts for understanding lung disease and may also offer novel and exciting avenues for therapeutic development.

Impact of Dietary Cholesterol on the Pathophysiology of Infectious and Autoimmune Disease

Cellular cholesterol metabolism, lipid raft formation, and lipoprotein interactions contribute to the regulation of immune-mediated inflammation and response to pathogens. Lipid pathways have been implicated in the pathogenesis of bacterial and viral infections, whereas altered lipid metabolism may contribute to immune dysfunction in autoimmune diseases, such as systemic lupus erythematosus, multiple sclerosis, and rheumatoid arthritis. Interestingly, dietary cholesterol may exert protective or detrimental effects on risk, progression, and treatment of different infectious and autoimmune diseases, although current findings suggest that these effects are variable across populations and different diseases. Research evaluating the effects of dietary cholesterol, often provided by eggs or as a component of Western-style diets, demonstrates that cholesterol-rich dietary patterns affect markers of immune inflammation and cellular cholesterol metabolism, while additionally modulating lipoprotein profiles and functional properties of HDL. Further, cholesterol-rich diets appear to differentially impact immunomodulatory lipid pathways across human populations of variable metabolic status, suggesting that these complex mechanisms may underlie the relationship between dietary cholesterol and immunity. Given the Dietary Guidelines for Americans 2015⁻2020 revision to no longer include limitations on dietary cholesterol, evaluation of dietary cholesterol recommendations beyond the context of cardiovascular disease risk is particularly timely. This review provides a comprehensive and comparative analysis of significant and controversial studies on the role of dietary cholesterol and lipid metabolism in the pathophysiology of infectious disease and autoimmune disorders, highlighting the need for further investigation in this developing area of research.

Ganoderma lucidum beta 1,3/1,6 glucan as an immunomodulator in inflammation induced by a high-cholesterol diet

BACKGROUND

Binding of beta 1,3/1,6 glucan of Ganoderma lucidum (G. lucidum) with the receptor results in a series of signal transfers (signalling cascades), which activates the transcription factors for regulating inflammation. Excess cholesterol intake leads to an increase in the distance between fat cells and capillaries, which may cause hypoxia in the fat tissue of obese mice. This hypoxia induces the death of fat cells, resulting in the inflammation of adipose tissue or an increase in the inflammatory gene expression associated with obesity.

METHODS

The current study examined the immunomodulation effect of G. lucidum beta 1,3/1,6 glucan according to immunoglobulin, poly-Ig receptor expression, Nature Killer cell (NK cell) activity, lymphocytes proliferation and cytokines expression.

RESULTS

Our present study shows that feeding G. lucidum beta 1,3/1,6 glucan to mice induces IgA or IgG expression in the serum and small intestine washing fluid and enhances poly-Ig receptor expression in the small intestine moreover, the observation of the IL-2 and Nature killer cell activity were exchanged.

CONCLUSIONS

The effect of a high-cholesterol diet in the inflammatory response was observed in heart, liver, kidney, spleen, and colon tissues through histopathological evaluations. The presented evidence demonstrates that the inflammation response in the high-cholesterol diet group was much higher than in the other groups and the beta 1,3/1,6 glucan reduces inflammation in obese mice fed a high-cholesterol diet.

Regulation of Adaptive Immunity in Health and Disease by Cholesterol Metabolism

Four decades ago, it was observed that stimulation of T cells induces rapid changes in cellular cholesterol that are required before proliferation can commence. Investigators returning to this phenomenon have finally revealed its molecular underpinnings. Cholesterol trafficking and its dysregulation are now also recognized to strongly influence dendritic cell function, T cell polarization, and antibody responses. In this review, the state of the literature is reviewed on how cholesterol and its trafficking regulate the cells of the adaptive immune response and in vivo disease phenotypes of dysregulated adaptive immunity, including allergy, asthma, and autoimmune disease. Emerging evidence supporting a potential role for statins and other lipid-targeted therapies in the treatment of these diseases is presented. Just as vascular biologists have embraced immunity in the pathogenesis and treatment of atherosclerosis, so should basic and clinical immunologists in allergy, pulmonology, and other disciplines seek to encompass a basic understanding of lipid science.

Lifestyle-Related Factors and Atopy in Seven Danish Population-Based Studies from Different Time Periods

BACKGROUND

The prevalence of allergic respiratory disease tends to increase in populations that adopt the so-called Westernized lifestyle. We investigated the association between atopy and several possible lifestyle-related factors in seven Danish population-based studies.

METHODS

A total of 20048 persons participated in the seven studies. We used logistic regression to analyse the associations between possible determinants and atopy defined as serum specific IgE or skin prick test positivity against inhalant allergens. Associations were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs). In addition, individual participant data meta-analyses were performed.

RESULTS

Atopy was significantly associated with younger age (OR per 1 year increase in age: 0.97; 95% CI: 0.97, 0.98); male sex (OR for males versus females: 1.34; 95% CI: 1.24, 1.45), heavy drinking (OR for heavy drinkers versus light drinkers: 1.15; 95% CI: 1.04, 1.27), never smoking (OR for current versus never smokers: 0.73; 95% CI: 0.67, 0.80), and higher educational level (OR for educated versus uneducated: 1.27; 95% CI: 1.15, 1.41). Atopy was not associated with blood pressure, serum total cholesterol, physical activity or body mass except in women only, where we found a positive association (OR for obese vs. normal weight: 1.18; 95% CI: 1.00, 1.39) with ptrend = 0.032.

CONCLUSIONS

Of interest for preventive purposes, we found that atopy was associated with some of the reversible lifestyle-related factors that characterize a Westernized lifestyle.

Blood lipid levels associate with childhood asthma, airway obstruction, bronchial hyperresponsiveness, and aeroallergen sensitization

BACKGROUND

Studies of children's blood lipid profiles in relation to asthma are few, and the results are ambiguous.

OBJECTIVE

We sought to examine whether the lipid profile is associated with concurrent asthma, altered lung function, and allergic sensitization in children.

METHODS

High-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride levels were measured at ages 5 to 7 years in the Copenhagen Prospective Studies on Asthma in Childhood2000 at-risk birth cohort. Asthma and allergic rhinitis were diagnosed based on predefined algorithms at age 7 years along with assessments of lung function, bronchial responsiveness, fraction of exhaled nitric oxide (Feno), and allergic sensitization. Associations between lipid levels and clinical outcomes were adjusted for sex, passive smoking, and body mass index.

RESULTS

High levels of low-density lipoprotein cholesterol were associated with concurrent asthma (adjusted odds ratio [aOR], 1.93; 95% CI, 1.06-3.55; P = .03) and airway obstruction: 50% of forced expiratory flow (aβ coefficient, -0.13 L/s; 95% CI, -0.24 to -0.03 L/s; P = .01) and specific airway resistance (aβ coefficient, 0.06 kPa/s; 95% CI, 0.00-0.11 kPa/s; P = .05). High levels of high-density lipoprotein cholesterol were associated with improved specific airway resistance (aβ coefficient, -0.11 kPa/s; 95% CI, -0.21 to -0.02; P = .02), decreased bronchial responsiveness (aβ coefficient, 0.53 log-μmol; 95% CI, 0.00-1.60 log-μmol; P = .05), decreased risk of aeroallergen sensitization (aOR, 0.27; 95% CI, 0.01-0.70; P = .01), and a trend of reduced Feno levels (aβ coefficient, -0.22 log-ppb; 95% CI, -0.50 to 0.01 log-ppb; P = .06). High triglyceride levels were associated with aeroallergen sensitization (aOR, 2.01; 95% CI, 1.14-3.56; P = .02) and a trend of increased Feno levels (aβ coefficient, 0.14 log-ppb; 95% CI, -0.02 to 0.30 log-ppb; P = .08).

CONCLUSION

The blood lipid profile is associated with asthma, airway obstruction, bronchial responsiveness, and aeroallergen sensitization in 7-year-old children. These findings suggest that asthma and allergy are systemic disorders with commonalities with other chronic inflammatory disorders.

Intratracheal instillation of pravastatin for the treatment of murine allergic asthma: a lung-targeted approach to deliver statins

Systemic treatment with statins mitigates allergic airway inflammation, T_H2 cytokine production, epithelial mucus production, and airway hyperreactivity (AHR) in murine models of asthma. We hypothesized that pravastatin delivered intratracheally would be quantifiable in lung tissues using mass spectrometry, achieve high drug concentrations in the lung with minimal systemic absorption, and mitigate airway inflammation and structural changes induced by ovalbumin. Male BALB/c mice were sensitized to ovalbumin (OVA) over 4 weeks, then exposed to 1% OVA aerosol or filtered air (FA) over 2 weeks. Mice received intratracheal instillations of pravastatin before and after each OVA exposure (30 mg/kg). Ultra performance liquid chromatography – mass spectrometry was used to quantify plasma, lung, and bronchoalveolar lavage fluid (BALF) pravastatin concentration. Pravastatin was quantifiable in mouse plasma, lung tissue, and BALF (BALF > lung > plasma for OVA and FA groups). At these concentrations pravastatin inhibited airway goblet cell hyperplasia/metaplasia, and reduced BALF levels of cytokines TNFα and KC, but did not reduce BALF total leukocyte or eosinophil cell counts. While pravastatin did not mitigate AHR, it did inhibit airway hypersensitivity (AHS). In this proof-of-principle study, using novel mass spectrometry methods we show that pravastatin is quantifiable in tissues, achieves high levels in mouse lungs with minimal systemic absorption, and mitigates some pathological features of allergic asthma. Inhaled pravastatin may be beneficial for the treatment of asthma by having direct airway effects independent of a potent anti-inflammatory effect. Statins with greater lipophilicity may achieve better anti-inflammatory effects warranting further research.

Targeting the mevalonate cascade as a new therapeutic approach in heart disease, cancer and pulmonary disease

The cholesterol biosynthesis pathway, also known as the mevalonate (MVA) pathway, is an essential cellular pathway that is involved in diverse cell functions. The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGCR) is the rate-limiting step in cholesterol biosynthesis and catalyzes the conversion of HMG-CoA to MVA. Given its role in cholesterol and isoprenoid biosynthesis, the regulation of HMGCR has been intensely investigated. Because all cells require a steady supply of MVA, both the sterol (i.e. cholesterol) and non-sterol (i.e. isoprenoid) products of MVA metabolism exert coordinated feedback regulation on HMGCR through different mechanisms. The proper functioning of HMGCR as the proximal enzyme in the MVA pathway is essential under both normal physiologic conditions and in many diseases given its role in cell cycle pathways and cell proliferation, cholesterol biosynthesis and metabolism, cell cytoskeletal dynamics and stability, cell membrane structure and fluidity, mitochondrial function, proliferation, and cell fate. The blockbuster statin drugs ('statins') directly bind to and inhibit HMGCR, and their use for the past thirty years has revolutionized the treatment of hypercholesterolemia and cardiovascular diseases, in particular coronary heart disease. Initially thought to exert their effects through cholesterol reduction, recent evidence indicates that statins also have pleiotropic immunomodulatory properties independent of cholesterol lowering. In this review we will focus on the therapeutic applications and mechanisms involved in the MVA cascade including Rho GTPase and Rho kinase (ROCK) signaling, statin inhibition of HMGCR, geranylgeranyltransferase (GGTase) inhibition, and farnesyltransferase (FTase) inhibition in cardiovascular disease, pulmonary diseases (e.g. asthma and chronic obstructive pulmonary disease (COPD)), and cancer.

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.

Is serum cholesterol a risk factor for asthma?

BACKGROUND

Proinflammatory role of serum cholesterol in asthma has been recently explored with contradicting results. Clarity on the link between serum cholesterol and asthma may lead to new evolutions in planning management strategies. The objective of our study was to examine the relationship between the serum cholesterol, asthma and its characteristics.

MATERIALS AND METHODS

A total of 40 asthmatics and 40 normal subjects were examined cross-sectionally and their serum fasting cholesterol and serum high sensitivity C reactive protein (hsCRP) levels were measured along with other baseline investigations. All subjects were non-smokers.

RESULTS

Serum total cholesterol (mean ± SD) among asthmatics was 176.45 ± 30.77 mgs/dL as compared to 163.33 ± 26.38 mgs/dL among normal subjects (P < 0.05). This higher serum cholesterol level was found to be associated with asthma independent of age, gender, body mass index (BMI), socio-economic status and serum hsCRP levels. However, the association was only modest (adjusted odds ratio 1.033; 95% confidence interval [CI] 1.008-1.059). There was no association between the serum cholesterol and asthma characteristics such as duration of illness, intake of inhaled steroids and frequency of emergency department visits. Other risk factors identified were poor ventilation (adjusted odds ratio 9.27; 95%CI 1.83-46.99) and overcrowding (adjusted odds ratio 41.9; 95% CI 3.15-557.46) at home.

CONCLUSION

Our study found a modest but significant association between higher levels of serum cholesterol and asthma, which is independent of age, gender, BMI, socio-economic status and serum hsCRP. Future research is required in a larger population to substantiate above association and its clinical implications. Poor ventilation and overcrowding at home are risk factors for asthma possibly facilitating increased exposure to indoor allergens.

Alendronate attenuates eosinophilic airway inflammation associated with suppression of Th2 cytokines, Th17 cytokines, and eotaxin-2

Bisphosphonates (BPs) have been widely used to treat osteoporosis. They act by inhibiting farnesyl diphosphate synthase in the mevalonate pathway. This resembles the action of statins, whose immune-modulating effect has recently been highlighted. In contrast, the effect of BPs on immune responses has not been elucidated well. In this study, we examined the effect of alendronate (ALN), a nitrogen-containing BP, on allergic airway inflammation in a mouse model. BALB/c mice were sensitized twice with OVA and challenged three times with nebulized OVA to induce eosinophilic airway inflammation. ALN was administered by an intragastric tube before each inhalation. ALN strongly suppressed airway eosinophilia and Th2, as well as Th17 cytokine production in the lung. ALN also attenuated eotaxin-2 production in the lung. Immunohistochemistry demonstrated that the major cell source of eotaxin-2 was peribronchial/perivascular macrophages, and flow cytometrical studies confirmed that ALN decreased eotaxin-2 expression in these macrophages. Furthermore, ALN attenuated eotaxin-2 production from mouse pleural macrophages and human monocyte/macrophage-like THP-1 cells in vitro. These results suggest that ALN suppressed Ag-induced airway responses in the mouse model. The suppression of eotaxin-2 production from macrophages appears to be one of ALN's immunomodulatory effects, whereas the mechanism by which ALN suppressed Th2 and Th17 responses could not be fully elucidated in this study. Although a clinical study should be conducted, ALN could be a novel therapeutic option for asthma.

Simvastatin inhibits smoke-induced airway epithelial injury: implications for COPD therapy

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death. The statin drugs may have therapeutic potential in respiratory diseases such as COPD, but whether they prevent bronchial epithelial injury is unknown. We hypothesised that simvastatin attenuates acute tobacco smoke-induced neutrophilic lung inflammation and airway epithelial injury. Spontaneously hypertensive rats were given simvastatin (20 mg·kg(-1) i.p.) daily for either 7 days prior to tobacco smoke exposure and during 3 days of smoke exposure, or only during tobacco smoke exposure. Pretreatment with simvastatin prior to and continued throughout smoke exposure reduced the total influx of leukocytes, neutrophils and macrophages into the lung and airways. Simvastatin attenuated tobacco smoke-induced cellular infiltration into lung parenchymal and airway subepithelial and interstitial spaces. 1 week of simvastatin pretreatment almost completely prevented smoke-induced denudation of the airway epithelial layer, while simvastatin given only concurrently with the smoke exposure had no effect. Simvastatin may be a novel adjunctive therapy for smoke-induced lung diseases, such as COPD. Given the need for statin pretreatment there may be a critical process of conditioning that is necessary for statins' anti-inflammatory effects. Future work is needed to elucidate the mechanisms of this statin protective effect.

Lipid profiles in children with and without asthma: interaction of asthma and obesity on hyperlipidemia

AIMS

The joint effect of obesity and asthma on hyperlipidemia has never been explored. We aim to examine (1) the association of dyslipidemia and asthma, (2) the interaction effect of asthma and obesity on hyperlipidemia, and (3) whether a gender difference existed in the above relationships.

METHODS

Between 2009 and 2010, 10- to 15-year-old children were recruited from 7 schools and 2 hospitals in Northern Taiwan. The population consisted of 237 asthmatic children and 225 non-asthmatic controls, and was further divided into four groups: non-obese controls, obese controls, non-obese asthmatics, and obese asthmatics. Measurements included anthropometric measures and blood samples for analysis of metabolic factors. The Cook's criteria were used to define childhood metabolic syndrome. General linear models were used to analyze how lipid profiles were associated with obesity and asthma.

RESULTS

Total cholesterol and low density lipoprotein cholesterol levels increased progressively in the group order obese asthmatics>non-obese asthmatics>obese controls>non-obese controls. In boys, low density lipoprotein cholesterol levels were significantly higher in obese asthmatics compared to obese non-asthmatics, with a mean difference of 6.2 mmol/L in the general linear model. We also discovered a significant interactive effect of obesity and asthma on hyperlipidemia in boys (p for interaction=0.03).

CONCLUSIONS

Asthma was associated with higher low density lipoprotein cholesterol levels and this association was amplified in overweight and obese subjects. A gender difference was observed in the joint effect of obesity and asthma on hyperlipidemia.

A systematic review of statin efficacy in asthma

BACKGROUND

Statins are known for their lipid-lowering effects and role in the treatment of atherosclerotic disease. They also have anti-inflammatory and immunomodulatory properties which could benefit asthma patients. We aimed to review the evidence on the efficacy and safety of statins in asthma-related outcomes.

METHODS

A systematic review of the literature on the effects of statins on asthma-related outcomes was performed following a search of the National Guideline Clearinghouse, Cochrane, Scopus, and Pubmed Medline databases in January 2012. Randomized controlled trials (RCTs) and observational studies (cohort/case-control design) assessing the effect of statins were included. The Grading of Recommendations Assessment Development and Evaluation (GRADE) system was used to rate the levels of evidence and grade of recommendation.

RESULTS

Twenty-four of the 379 articles retrieved electronically and one article identified by hand search were selected for full-text scrutiny by two independent reviewers. Eight studies were included: six RCTs and two observational studies. Statin use was not associated with consistent, statistical significant improvements in patient outcomes (asthma control, quality of life, steroid-sparing effects) or disease outcomes (lung function, airway responsiveness), and all the studies analyzed had low or very low quality of evidence. Inflammatory outcome improvements were observed in mild allergic asthma.

CONCLUSION

Statins do not seem to have any additional benefit in asthma control or steroid-sparing effect in asthma treatment. Considering the prevalence of both statin use and asthma, more, better designed studies are needed to determine whether a specific phenotype of asthma exists that could benefit from statin treatment.

Effect of β-glucan originated from Aureobasidium pullulans on asthma induced by ovalbumin in mouse

The objective of this study is to detect the effect of beta-glucan derived from Aureobasidium pullulans SM-2001, a UV induced mutant of A. pullulans on the ovalbumin (OVA) induced allergic asthma. The test articles were orally administered to OVA-inducing asthmatic mice 4 days after sensitization for 13 days at 31.25, 62.5 or 125 mg/kg levels. Three days after the OVA sensitization, ten mice were selected per group based on body weight and were sacrificed three days after the OVA aerosol challenge. The changes on the body weight, lung weight, total leukocytes in peripheral blood and total cells in bronchoalveolar lavage fluid (BALF) were observed with changes on the lung histopathology and histomorphometry. The results were compared with dexamethasone (DEXA) 3 mg/kg intraperitoneally treated mice. The results showed increases of body weight after the OVA aerosol challenge, lung weight, total leukocytes and eosinophils in peripheral blood, total cell numbers, neutrophil and eosinophils in BALF were detected in the OVA control compared to sham control (non-OVA). However, these changes from asthmatic responses were significantly or dose-dependently decreased in the beta-glucan-dosing groups compared to those of the OVA control. Therefore, it is concluded that beta-glucan has favorable effects on asthmatic response induced by OVA. It was found that beta-glucan 125 mg/kg showed similar or slightly lower efficacy compared with DEXA 3 mg/kg.

Emerging roles for cholesterol and lipoproteins in lung disease

Dyslipidemia, the condition of elevated serum triglycerides, elevated low-density lipoprotein cholesterol, and/or low high-density lipoprotein cholesterol, is a public health problem of growing concern. Dyslipidemia clusters with other disorders of the metabolic syndrome that together influence, and may derive from, chronic inflammation. While best recognized as a risk factor for atherosclerotic cardiovascular disease, lipid dysregulation has recently been shown to influence a variety of disease processes in several organ systems. This review highlights our current understanding of the role of cholesterol and its homeostatic trafficking in pulmonary physiology and pathophysiology. Gene-targeted mice deficient in regulatory proteins that govern reverse cholesterol transport (e.g., ATP Binding Cassette transporter G1, apolipoprotein E) have recently been shown to have abnormal lung physiology, including dysregulated pulmonary innate and adaptive immune responses to the environment. It has also recently been shown that diet-induced dyslipidemia alters trafficking of immune cells to the lung in a manner that may have important implications for the pathogenesis of acute lung injury, asthma, pneumonia, and other lung disorders. Conversely, cholesterol-targeting pharmacologic agents, such as statins, apolipoprotein mimetic peptides, and Liver X Receptor agonists, have shown early promise in the treatment of several lung disorders. An improved understanding of the precise molecular mechanisms by which cholesterol and its trafficking modify pulmonary immunity will be required before the full implications of dyslipidemia as a lung disease modifier, and the full potential of lipid-targeting agents as pulmonary therapeutics, can be realized.

Genetic interactions between chromosomes 11 and 18 contribute to airway hyperresponsiveness in mice

We used two-dimensional quantitative trait locus analysis to identify interacting genetic loci that contribute to the native airway constrictor hyperresponsiveness to methacholine that characterizes A/J mice, relative to C57BL/6J mice. We quantified airway responsiveness to intravenous methacholine boluses in eighty-eight (C57BL/6J X A/J) F₂ and twenty-seven (A/J X C57BL/6J) F₂ mice as well as ten A/J mice and six C57BL/6J mice; all studies were performed in male mice. Mice were genotyped at 384 SNP markers, and from these data two-QTL analyses disclosed one pair of interacting loci on chromosomes 11 and 18; the homozygous A/J genotype at each locus constituted the genetic interaction linked to the hyperresponsive A/J phenotype. Bioinformatic network analysis of potential interactions among proteins encoded by genes in the linked regions disclosed two high priority subnetworks - Myl7, Rock1, Limk2; and Npc1, Npc1l1. Evidence in the literature supports the possibility that either or both networks could contribute to the regulation of airway constrictor responsiveness. Together, these results should stimulate evaluation of the genetic contribution of these networks in the regulation of airway responsiveness in humans.

Statin drugs, metabolic pathways, and asthma: a therapeutic opportunity needing further research

The chance discovery of hydroxymethylglutaryl (HMG)-CoA reductase inhibitors has revolutionized the care of patients with cardiovascular disease. The unexpected finding that these cholesterol-lowering drugs (or 'statins') also possess pleiotropic immunomodulatory properties, has opened a new area of research which investigates the anti-inflammatory and anti-proliferative properties of statins. In this brief commentary, we discuss the potential application of these drugs in asthma, where metabolic pathways pertinent to lung inflammation, in addition to the mevalonate cascade, may be targeted. We review mechanisms of action, discuss the potential therapeutic use of statins in asthma, share some preliminary data from our laboratory, discuss results from recent clinical trials in asthma, and propose a new target asthma subpopulation that could potentially benefit. We conclude our essay by highlighting the mevalonate-dependent and -independent pathways that may be modulated by statins, including the emerging area of cholesterol, sphingolipid, and lipid raft biology in lung disease. In this is an opportunity to develop new treatments for asthma, where innovative therapies are urgently needed to prevent acute exacerbations and alter disease progression.

Relationship of serum cholesterol levels to atopy in the US population

BACKGROUND

Cholesterol promotes Th2 immunity and allergic inflammation in rodents; whether this occurs in humans is unclear. Reports of both direct and inverse associations between serum cholesterol and atopy in different populations suggest that race and/or other demographic variables may modify these relationships.

AIMS OF THE STUDY

To determine the relationships between levels of three serum cholesterol measures [total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), and non-HDL-C] and atopy in a sample representative of the US population.

METHODS

Cross-sectional study of 6854 participants aged > or =6 years from the 2005-2006 National Health and Nutrition Examination Survey.

RESULTS

In the overall population, adjusted odds ratios (AORs) per two-standard deviation increase in TC and non-HDL-C for biochemical atopy (defined as > or =1 allergen-specific IgE to 19 allergens) were 1.17 [95% confidence interval (CI), 1.00-1.38] and 1.19 (95% CI, 1.03-1.39), respectively. Interactions by race were noted for the two relationships (interaction P = 0.004 and P = 0.009, respectively) with non-Hispanic Whites (NHWs) having direct relationships [TC: AOR 1.27 (95% CI, 1.03-1.57); non-HDL-C: AOR 1.27 (95% CI, 1.03-1.56)] and non-Hispanic Blacks (NHBs) inverse relationships [TC: AOR 0.77 (95% CI, 0.62-0.95); non-HDL-C: AOR 0.86 (95% CI, 0.69-1.08)]. The adjusted HDL-C-atopy relationship was nonsignificant for NHWs and inverse for NHBs [AOR 0.77 (95% CI, 0.61-0.96)]. Relationships were independent of body mass index and serum C-reactive protein and unmodified by corticosteroid or statin usage. Results were similar using current hay fever/allergy as the atopy outcome.

CONCLUSIONS

There are marked inter-racial differences in the relationship between serum cholesterol and atopy in the US population.

Interleukin-17 regulation: an attractive therapeutic approach for asthma

Interleukin (IL)-17 is recognized to play a critical role in numerous immune and inflammatory responses by regulating the expression of various inflammatory mediators, which include cytokines, chemokines, and adhesion molecules. There is growing evidence that IL-17 is involved in the pathogenesis of asthma. IL-17 orchestrates the neutrophilic influx into the airways and also enhances T-helper 2 (Th2) cell-mediated eosinophilic airway inflammation in asthma. Recent studies have demonstrated that not only inhibitor of IL-17 per se but also diverse regulators of IL-17 expression reduce antigen-induced airway inflammation, bronchial hyperresponsiveness, and Th2 cytokine levels in animal models of asthma. This review will summarize the role of IL-17 in the context of allergic airway inflammation and discuss the therapeutic potential of various strategies targeting IL-17 for asthma.

Simvastatin inhibits airway hyperreactivity: implications for the mevalonate pathway and beyond

RATIONALE

Statin use has been linked to improved lung health in asthma and chronic obstructive pulmonary disease. We hypothesize that statins inhibit allergic airway inflammation and reduce airway hyperreactivity via a mevalonate-dependent mechanism.

OBJECTIVES

To determine whether simvastatin attenuates airway inflammation and improves lung physiology by mevalonate pathway inhibition.

METHODS

BALB/c mice were sensitized to ovalbumin over 4 weeks and exposed to 1% ovalbumin aerosol over 2 weeks. Simvastatin (40 mg/kg) or simvastatin plus mevalonate (20 mg/kg) was injected intraperitoneally before each ovalbumin exposure.

MEASUREMENTS AND MAIN RESULTS

Simvastatin reduced total lung lavage leukocytes, eosinophils, and macrophages (P < 0.05) in the ovalbumin-exposed mice. Cotreatment with mevalonate, in addition to simvastatin, reversed the antiinflammatory effects seen with simvastatin alone (P < 0.05). Lung lavage IL-4, IL-13, and tumor necrosis factor-alpha levels were all reduced by treatment with simvastatin (P < 0.05). Simvastatin treatment before methacholine bronchial challenge increased lung compliance and reduced airway hyperreactivity (P = 0.0001).

CONCLUSIONS

Simvastatin attenuates allergic airway inflammation, inhibits key helper T cell type 1 and 2 chemokines, and improves lung physiology in a mouse model of asthma. The mevalonate pathway appears to modulate allergic airway inflammation, while the beneficial effects of simvastatin on lung compliance and airway hyperreactivity may be independent of the mevalonate pathway. Simvastatin and similar agents that modulate the mevalonate pathway may prove to be treatments for inflammatory airway diseases, such as asthma.

Lovastatin inhibits antigen-induced airway eosinophilia without affecting the production of inflammatory mediators in mice

OBJECTIVE AND DESIGN

Statins have been proposed as a novel treatment of respiratory diseases. To determine the beneficial effects of statins on allergic bronchial asthma, the effect of systemic treatment with lovastatin on antigen-induced airway inflammation was investigated.

SUBJECTS

Male BALB/c mice were used.

TREATMENTS

Mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen to induce asthmatic response. Animals were also treated with lovastatin (4 mg/kg/day, i.p.) once a day prior to and during the antigen inhalation period.

METHODS

Inflammatory cell counts and levels of interleukin (IL)-4, IL-13, eotaxin, thymus and activation-regulated chemokine and leukotriene B(4) (LTB(4)) in bronchoalveolar lavage (BAL) fluids were measured.

RESULTS

Significant increases in eosinophils and levels of the T helper 2 cytokines, chemokines and LTB(4) in BAL fluids in association with the increments of total and OA-specific immunoglobulin E (IgE) in sera were observed in the repeatedly antigen-challenged mice. The airway eosinophilia was ameliorated by lovastatin, whereas it had no significant effect on the levels of these inflammatory mediators or IgE.

CONCLUSION

Lovastatin may be beneficial for the treatment of allergic inflammatory diseases in the airways, such as allergic bronchial asthma.

LXR-induced reverse cholesterol transport in human airway smooth muscle is mediated exclusively by ABCA1

The association of hypercholesterolemia and obesity with airway hyperresponsiveness has drawn increasing attention to the potential role of cholesterol and lipid homeostasis in lung physiology and in chronic pulmonary diseases such as asthma. We have recently shown that activation of the nuclear hormone receptor liver X receptor (LXR) stimulates cholesterol efflux in human airway smooth muscle (hASM) cells and induces expression of the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, members of a family of proteins that mediate reverse cholesterol and phospholipid transport. We show here that ABCA1 is responsible for all LXR-mediated cholesterol and phospholipid efflux to both apolipoprotein AI and high-density lipoprotein acceptors. In contrast, ABCG1 does not appear to be required for this process. Moreover, we show that hASM cells respond to increased levels of cholesterol by inducing expression of ABCA1 and ABCG1 transporters, a process that is dependent on LXR expression. These findings establish a critical role for ABCA1 in reverse cholesterol and phospholipid transport in airway smooth muscle cells and suggest that dysregulation of cholesterol homeostasis in these cells may be important in the pathogenesis of diseases such as asthma.

Loss of ABCG1 results in chronic pulmonary inflammation

ABCG1, a member of the ATP-binding cassette transporter superfamily, is highly expressed in multiple cells of the lung. Loss of ABCG1 results in severe pulmonary lipidosis in mice, with massive deposition of cholesterol in both alveolar macrophages and type 2 cells and the accumulation of excessive surfactant phospholipids. These observations are consistent with ABCG1 controlling cellular sterol metabolism. Herein, we report on the progressive and chronic inflammatory process that accompanies the lipidosis in the lungs of Abcg1-/- mice. Compared with wild-type animals, the lungs of aged chow-fed mice deficient in ABCG1 show distinctive signs of inflammation that include macrophage accumulation, lymphocytic infiltration, hemorrhage, eosinophilic crystals, and elevated levels of numerous cytokines and cytokine receptors. Analysis of bronchoalveolar lavages obtained from Abcg1-/- mice revealed elevated numbers of foamy macrophages and leukocytes and the presence of multiple markers of inflammation including crystals of chitinase-3-like proteins. These data suggest that cholesterol and/or cholesterol metabolites that accumulate in Abcg1-/- lungs can trigger inflammatory signaling pathways. Consistent with this hypothesis, the expression of a number of cytokines was found to be significantly increased following increased cholesterol delivery to either primary peritoneal macrophages or Raw264.7 cells. Finally, cholesterol loading of primary mouse macrophages induced cytokine mRNAs to higher levels in Abcg1-/-, as compared with wild-type cells. These results demonstrate that ABCG1 plays critical roles in pulmonary homeostasis, balancing both lipid/cholesterol metabolism and inflammatory responses.

Lovastatin inhibits bronchial hyperresponsiveness by reducing RhoA signaling in rat allergic asthma

Recent studies revealed an importance of a monomeric GTP-binding protein, RhoA, in contraction of bronchial smooth muscle (BSM). RhoA and its downstream have been proposed as a new target for the treatment of airway hyperresponsiveness in asthma. Statins are known to inhibit the functional activation of RhoA via the depletion of geranylgeranylpyrophosphate. To determine the beneficial effects of statins on the airway hyperresponsiveness in allergic bronchial asthma, we investigated the effects of systemic treatment with lovastatin on the augmented BSM contraction and activation of RhoA in rats with allergic bronchial asthma. Rats were sensitized and repeatedly challenged with 2,4-dinitrophenylated Ascaris suum antigen. Animals were also treated with lovastatin (4 mg kg(-1) day(-1) ip) once a day before and during the antigen inhalation period. Repeated antigen inhalation caused a marked BSM hyperresponsiveness to ACh with the increased expression and translocation of RhoA. Lovastatin treatments significantly attenuated both the augmented contraction and RhoA translocation to the plasma membrane. Lovastatin also reduced the increased cell number in bronchoalveolar lavage fluids and histological changes induced by antigen exposure, whereas the levels of immunoglobulin E in sera and interleukins-4, -6, and -13 in bronchoalveolar lavage fluids were not significantly changed. These findings suggest that lovastatin ameliorates antigen-induced BSM hyperresponsiveness, an important factor of airway hyperresponsiveness in allergic asthmatics, probably by reducing the RhoA-mediated signaling.

Macrophage beta3 integrin suppresses hyperlipidemia-induced inflammation by modulating TNFalpha expression

OBJECTIVE

High-fat, cholesterol-containing diets contribute to hyperlipidemia. Both high-fat diets and hyperlipidemia are associated with chronic inflammatory diseases like atherosclerosis. Integrins, heterodimeric mediators of inflammatory cell recruitment, are not generally thought to be affected by diet. However, high-fat feeding promotes inflammation, atherosclerosis, and death in hyperlipidemic mice with beta3 integrin deficiency, and treatment of humans from Western populations with oral beta3 integrin inhibitors increases mortality. The mechanisms responsible for these beta3 integrin-associated events are unknown.

METHODS AND RESULTS

Here we show that diet-induced death in beta3 integrin-deficient mice is a TNFalpha-dependent process mediated by bone marrow-derived cells. In 2 different hyperlipidemic models, apoE-null and LDL receptor-null mice, beta3-replete animals transplanted with beta3-deficient marrow died with Western-type high-fat feeding whereas beta3-deficient animals transplanted with beta3-replete marrow were rescued from diet-induced death. Transplantation with beta3-deficient marrow also increased atherosclerosis. TNFalpha [corrected] expression was increased in beta3-deficient macrophages and normalized by either retroviral or adenoviral reconstitution of beta3 integrin expression. Treatment with the anti-TNFalpha antibody infliximab rescued beta3 integrin-deficient mice from Western diet-induced death, directly implicating TNFalpha in the pathophysiology triggered by diet-induced hyperlipidemia.

CONCLUSIONS

These findings suggest that macrophage beta3 integrin, acting through TNFalpha, suppresses inflammation caused by hyperlipidemia attributable to high-fat feeding.

Liver X receptor stimulates cholesterol efflux and inhibits expression of proinflammatory mediators in human airway smooth muscle cells

Human (h) airway smooth muscle (ASM) cells are important mediators of the inflammatory process observed in asthma and other respiratory diseases. We show here that primary hASM cells express liver X receptor (LXR; alpha and beta subtypes), an oxysterol-activated nuclear receptor that controls expression of genes involved in lipid and cholesterol homeostasis, and inflammation. LXR was functional as determined by transient assays using LXR-responsive reporter genes and by analysis of mRNA and protein expression of endogenous LXR target genes in cells exposed to LXR agonists. LXR activation induced expression of the ATP-binding cassette transporters ABCA1 and ABCG1 and increased efflux of cholesterol to apolipoprotein AI and high-density lipoprotein acceptors, pointing to a role for hASM cells in modulating cholesterol homeostasis in the airway. Under inflammatory conditions, hASM cells release a variety of chemokines and cytokines that contribute to inflammatory airway diseases. Activation of LXR inhibited the expression of multiple cytokines in response to proinflammatory mediators and blocked the release of both granulocyte macrophage colony-stimulating factor and granulocyte colony stimulating factor. LXR activation also inhibited proliferation of hASM cells and migration toward platelet-derived growth factor chemoattractant, two important processes that contribute to airway remodeling. Our findings reveal biological roles for LXR in ASM cells and suggest that modulation of LXR activity offers prospects for new therapeutic approaches in the treatment of asthma and other inflammatory respiratory diseases.

Potential therapeutic role for statins in respiratory disease

Statins reduce cholesterol levels by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and have an established role in the treatment of atherosclerotic disease. Recent research has identified anti-inflammatory properties of statins. Statins appear to reduce the stability of lipid raft formation with subsequent effects on immune activation and regulation, and also prevent the prenylation of signalling molecules with subsequent downregulation of gene expression. Both these effects result in reduced cytokine, chemokine, and adhesion molecule expression, with effects on cell apoptosis or proliferation. This review considers the evidence for the anti-inflammatory properties of statins in the lung, and how these effects are being applied to research into the role of statins as a novel treatment of respiratory diseases.

Hypercholesterolemia is a potential risk factor for asthma

INTRODUCTION

The effect of hyperlipidemia on asthma has never been addressed. Recent literature implicates a pro-inflammatory role for hypercholesterolemia. This study evaluates the effect of serum cholesterol level on asthma frequency.

METHODS

Factors associated with asthma risk were examined in a retrospective study design. Study subjects were between the 4 and 20 years of age who presented to a rural pediatric clinic and whose total serum cholesterol level was obtained. Diagnosis of asthma was determined by the treating physician. Multivariable logistic regression was performed to identify variables that were related to the odds of having asthma.

RESULTS

A total of 188 patients were included. Asthma was present in 50 patients. Total serum cholesterol (mean +/- SD) for the asthma group was 176.7 +/- 39.8 compared to 162.9 +/- 12.8 in the non-asthma group (P = 0.028). A total of 21 of the 50 (42%) asthma patients were obese compared to 31 of the 138 (22%) non-asthma patients (p = 0.014). There was no difference between both groups regarding age and gender. Hypercholesterolemia and obesity were identified by logistic regression analysis to increase the probability of asthma independently.

CONCLUSION

Hypercholesterolemia is a potential risk factor for asthma independent of obesity.

Effect of simvastatin, an established lipid-lowering drug, on pulmonary Chlamydia pneumoniae infection in mice

The effects of simvastatin treatment on Chlamydia pneumoniae lung infection, inflammation, and serum lipids in mouse model were studied. Simvastatin decreased viable chlamydial counts and increased inflammatory cell infiltrates in the lung tissue, suggesting that simvastatin treatment had both antichlamydial and immunomodulatory effects during an acute C. pneumoniae infection.