The role of osteopontin in lung disease

Plasma osteopontin velocity differentiates lung cancers from controls in a CT screening population

INTRODUCTION

As CT screening is integrated into non-small cell lung cancer (NSCLC) care, additional parameters are needed to help distinguish cancers from benign nodules. Osteopontin (OPN), a secreted phosphoprotein, has elevated plasma levels in NSCLC. We hypothesize that changes in plasma OPN over time (i.e., OPN velocity [OPNV]) can differentiate NSCLC patients from those without cancer in a CT screening population.

METHODS

A nested case-control study was conducted within a NSCLC CT screening trial. Incident cancers with serial plasma were matched to controls. OPN was measured by ELISA. Demographic, OPN, and OPNV were compared between cancers and controls using Wilcoxon Signed Rank tests.

RESULTS

Ten incident cancers were identified. The pack years distributions were similar, but cancers were older (median of the paired difference: 5.35 years; p=0.002) and their surveillance intervals were shorter (median of the paired difference: -2 months; p=0. 03) than matched controls. Baseline OPN was similar (median of the paired difference: -5.15 ng/ml, p=0.50), but OPNV in the cancers was significantly greater than that of matched controls, (median of the paired difference: 1.06 ng/ml/month, p=0.01). Accuracy rate for prediction of disease status based on OPNV (adjusted for age and surveillance) was 83%.

CONCLUSIONS

These are early evidence for utility of monitoring plasma OPN during CT screening to assist in identification of NSCLCs.

Plasma osteopontin levels are associated with disease activity in the patients with multiple sclerosis and neuromyelitis optica

Osteopontin (OPN) up-regulates pro-inflammatory cytokines from both T helper type 1 and T helper type 17 cell pathways. We measured plasma OPN levels in Japanese multiple sclerosis (MS) and neuromyelitis optica (NMO) patients to investigate its value as a potential biomarker of disease activity. In NMO patients, plasma OPN levels were significantly higher than those in healthy individuals, being equivalent to those in MS patients. In both NMO and MS patients, OPN levels were significantly higher during relapse compared with remission. There was also a significant positive correlation between Expanded Disability Status Scale of Kurzke scores and plasma OPN levels in both NMO and MS patients, and plasma OPN levels were significantly higher in patients with secondary progressive MS compared with those with relapsing-remitting MS. Diagnostic sensitivity and specificity of plasma OPN for MS and NMO during the relapse phase were 100% and 50%, respectively (cut-off point: 31.3ng/ml). Thus, elevated plasma OPN levels could be a potential biomarker for not only MS but also NMO. These are the first results to suggest that plasma OPN in NMO patients may be a useful marker, playing an important role in inflammation, disease activity, and disease progression, as well as MS.

Osteopontin as a two-sided mediator in acute neuroinflammation in rat models

Osteopontin (OPN) plays an important role in the initiation of inflammation, affecting cell adhesion, chemotaxis, immune regulation, and protection against apoptosis, depending on its intracellular or extracellular localization. Although OPN in inflammation of the autoimmune central nervous system is proinflammatory, recent studies have shown that OPN during the induction stage of inflammation may also participate in neuroprotection and neurite growth. The present review examines the dual roles of OPN, specifically, its proinflammatory and subsequent neuroprotective roles, in acute neuroinflammation in rat models, including experimental autoimmune encephalomyelitis, brain injury, and autoimmune neuritis. All of these models are characterized by acute neuroinflammation, followed by remodeling of neural tissues.

Phosphorylation of osteopontin in osteoarthritis degenerative cartilage and its effect on matrix metalloprotease 13

The purpose of this study is to observe the differences of osteopontin (OPN) phosphorylation in osteoarthritis (OA) cartilage and normal cartilage, and evaluate the possible correlations between the OPN phosphorylation and MMP-13 expression. Degenerative cartilage (n = 29) and normal cartilage (n = 10) were identified by hematoxylin-eosin, safranin-O staining and modified Mankin score. The phosphorylation level of OPN in OA cartilage and normal cartilage was detected by immunoprecipitation. Chondrocytes were treated with phospho-OPN, OPN or buffer. Quantitative reverse transcription polymerase chain reaction (qPCR) and ELISA were used to assess the expression of MMP-13 in different treatments. The OD values of phosphorylation of OPN in normal cartilage and OA cartilage were 137.89 ± 10.59 and 153.52 ± 8.80, respectively, (P = 0.000). Chondrocytes treated with OPN showed a higher MMP-13 expression at gene and protein level compared with control group. Chondrocytes treated with phospho-OPN showed the highest MMP-13 expression in gene and protein. In conclusion, our results revealed a higher phosphorylation level of OPN in OA cartilage than in normal cartilage. We found OPN leads to elevated expression of MMP-13 (both at gene level and protein level), and phospho-OPN had a more obvious upregulation effect on MMP-13 expression than nonphospho-OPN. Further studies are needed to reveal the mechanism of OPN phosphorylation on cartilage degeneration.

Osteopontin contributes to TGF-β1 mediated hepatic stellate cell activation

BACKGROUND AND PURPOSE

Liver fibrosis is characterized by accumulation of extracellular matrix. Our previous study found that osteopontin (OPN) increased in plasma of cirrhotic patients and indicative of cirrhosis staging. The present study was designed to investigate the expression of OPN in liver tissues and plasma of cirrhotic patients and further explore the role of OPN in human hepatic stellate cell (HSC) activation.

METHODS

We used immunohistochemical staining and enzyme-linked immunosorbent assay to evaluate the expression level of OPN in liver tissues and plasma from cirrhotic patients, respectively. We produced lentivirus particles and infected target cell to manipulate OPN expression. Infection efficiency was determined by real-time RT-PCR and western blot. Cell proliferation was determined using CCK8 assay, and phenotypes of HSC activation were determined by real-time RT-PCR. OPN promoter activity was determined by dual luciferase reporter assay.

RESULTS

We found that OPN expression in human cirrhotic liver tissues was upregulated compared to normal controls. In addition, its expression correlated with Child-Pugh classification, MELD score and the occurrence of complications. We further explored OPN level in patients' plasma and showed that its level correlated with transforming growth factor-β1 (TGF-β1). In human HSC cell line LX-2, we found that change of OPN expression level could not only affect the proliferation of cells but also the TGF-β1 mediated HSC activation. Moreover, OPN was increased by TGF-β1 stimulation and regulated by TGF-β1 at transcription level.

CONCLUSIONS

OPN is upregulated in liver tissues and plasma of cirrhotic patients and promotes TGF-β1 mediated HSC activation.

Quinolone-induced upregulation of osteopontin gene promoter activity in human lung epithelial cell line A549

Quinolones, in addition to their antibacterial activities, act as immunomodulators. Osteopontin (OPN), a member of the extracellular matrix proteins, was found to play a role in the immune and inflammatory response. We found that quinolones significantly enhanced OPN secretion, namely, garenoxacin (220%), moxifloxacin (62%), gatifloxacin (82%), sparfloxacin, (79%), and sitafloxacin (60%). Enhancement of OPN secretion was shown to be due to the effect of quinolones on the OPN gene promoter activity. We also examined the role of quinolones on apoptosis and found that sparfloxacin decreased the late apoptosis of A549 cells, but garenoxacin did not show the antiapoptotic effect. The antiapoptotic effects of quinolones do not appear to be associated with OPN elevation.

Osteopontin in systemic sclerosis and its role in dermal fibrosis

Osteopontin (OPN) is a matricellular protein with proinflammatory and profibrotic properties. Previous reports demonstrate a role for OPN in wound healing and pulmonary fibrosis. Here, we determined whether OPN levels are increased in a large cohort of patients with systemic sclerosis (SSc) and whether OPN contributes to the development of dermal fibrosis. The plasma OPN levels were increased in SSc patients, including patients with limited and diffuse disease, compared with healthy controls. Immunohistology demonstrated OPN on fibroblast-like and inflammatory cells in SSc skin and lesional skin from mice in the bleomycin (bleo)-induced dermal fibrosis model. OPN-deficient (OPN(-/-)) mice developed less dermal fibrosis compared with wild-type (WT) mice in the bleo-induced dermal fibrosis model. Additional in vivo studies have demonstrated that lesional skin from OPN(-/-)mice had fewer Mac-3-positive cells, fewer myofibroblasts, decreased transforming growth factor (TGF)-β and genes in the TGF-β pathway, and decreased numbers of cells expressing phosphorylated SMAD2 (pSMAD) and extracellular signal-regulated kinase. In vitro, OPN(-/-) dermal fibroblasts had decreased migratory capacity but similar phosphorylation of SMAD2 by TGF-β. Finally, TGF-β production by OPN-deficient macrophages was reduced compared with WT. These data demonstrate an important role for OPN in the development of dermal fibrosis and suggest that it may be a new therapeutic target in SSc.

Multiwalled carbon nanotube-induced gene signatures in the mouse lung: potential predictive value for human lung cancer risk and prognosis

Concerns over the potential for multiwalled carbon nanotubes (MWCNT) to induce lung carcinogenesis have emerged. This study sought to (1) identify gene expression signatures in the mouse lungs following pharyngeal aspiration of well-dispersed MWCNT and (2) determine if these genes were associated with human lung cancer risk and progression. Genome-wide mRNA expression profiles were analyzed in mouse lungs (n = 160) exposed to 0, 10, 20, 40, or 80 μg of MWCNT by pharyngeal aspiration at 1, 7, 28, and 56 d postexposure. By using pairwise statistical analysis of microarray (SAM) and linear modeling, 24 genes were selected, which have significant changes in at least two time points, have a more than 1.5-fold change at all doses, and are significant in the linear model for the dose or the interaction of time and dose. Additionally, a 38-gene set was identified as related to cancer from 330 genes differentially expressed at d 56 postexposure in functional pathway analysis. Using the expression profiles of the cancer-related gene set in 8 mice at d 56 postexposure to 10 μg of MWCNT, a nearest centroid classification accurately predicts human lung cancer survival with a significant hazard ratio in training set (n = 256) and test set (n = 186). Furthermore, both gene signatures were associated with human lung cancer risk (n = 164) with significant odds ratios. These results may lead to development of a surveillance approach for early detection of lung cancer and prognosis associated with MWCNT in the workplace.

Role of aldosterone on lung structural remodelling and right ventricular function in congestive heart failure

Background

The mechanisms of benefit of mineralocorticoid receptors antagonists in congestive heart failure (CHF) are still debated. We hypothesized that aldosterone contributes to pulmonary remodelling and right ventricular (RV) dysfunction associated with CHF by stimulation of lung myofibroblasts (MYFs) proliferation.

Methods

Rats with moderate to large myocardial infarcts (MI) and CHF were studied. Two weeks after MI, spironolactone 100 mg/kg/day (n = 21) or no treatment (n = 24) were given for 3 weeks and compared to sham (n = 8).

Results

Infarct size was similar by ultrasound and pathologic measures in both MI groups.

The MI-untreated group developed important lung remodelling with nearly doubling of dry lung weight (p < 0.01), reduced left ventricular (LV) fractional shortening (16 ± 2% vs. 53 ± 1%; mean ± SEM, p < 0.0001), pulmonary hypertension (RV systolic pressure: 40 ± 3 mmHg vs. 27 ± 1 mmHg, p < 0.01) and RV hypertrophy (RV/(LV + septum): 38 ± 3% vs. 24 ± 1%, p < 0.05). Spironolactone had no effect on these parameters and did not improve LV or RV performance (tricuspid annular plane systolic excursion and RV myocardial performance index) measured by echocardiography. CHF induced a restrictive respiratory syndrome with histological lung fibrosis: this was also unaffected by spironolactone. Finally, isolated lung MYFs did not proliferate after exposure to aldosterone.

Conclusion

Aldosterone does not significantly contribute to pulmonary remodelling and RV dysfunction associated with CHF. Other mechanisms are responsible for the beneficial effects of spironolactone in CHF.

Polymorphism in Osteopontin Gene (SPP1) Is Associated with Asthma and Related Phenotypes in a Puerto Rican Population

Recent studies have shown that osteopontin, a cytokine with suggested immunoregulatory functions, may contribute to pathogenesis of asthma. To determine whether single-nucleotide polymorphisms (SNPs) in SPP1, the gene encoding osteopontin, are associated with risk of asthma, we genotyped 6 known SNPs in SPP1 in the well-characterized Genetics of Asthma in Latino Americans population of 294 Mexican and 365 Puerto Rican parent-child asthma trios. The associations between SNPs and asthma or asthma-related phenotypes were examined by transmission disequilibrium tests as implemented in the family-based association test program. Three polymorphisms, 1 in exon 7 (rs1126616C) and 2 in the 3'-untranslated region (rs1126772A and rs9138A) of SPP1, were associated with diagnosis of asthma, severity of asthma, asthma in subjects with elevated immunoglobulin E (IgE) (IgE >100 IU/mL), and postbronchodilator FEV(1) in Puerto Ricans (P values=0.00007-0.04). The CC genotype of rs1126616 conferred an odds ratio of 1.7 (95% CI=[1.3, 2.3], P value adjusted for multiple comparisons=0.001) for asthma compared with the CT and TT genotypes. Furthermore, haplotype analysis identified rs1126616C-rs1126772A-rs9138A to be associated with an increased risk for asthma, severity of asthma, and asthma in subjects with elevated IgE (P=0.03). There was no association between the SPP1 SNPs and asthma outcomes in Mexicans. Our findings suggest that the SPP1 gene is a risk factor for asthma and asthma-related phenotypes in Puerto Ricans, and are consistent with previous animal and human studies on the role of osteopontin in pathogenesis of asthma.

Osteopontin as a marker of weight loss in lung cancer

Although the role of osteopontin (OPN) in tumorigenesis and invasiveness is well-known, its role in systemic consequences of lung cancer has not been studied yet. The objective of the current study was to assess the value of osteopontin as a marker of weight loss in relation to systemic inflammation in non-small cell lung cancer (NSCLC) patients. A total of 63 male NSCLC patients (stage III and IV) and 25 age and sex-matched controls were included. The NSCLC patients were further divided into subgroups depending on whether they had > 5% weight loss in the last 6 months or not. Serum OPN and TNF-α concentrations were measured by ELISA using commercially available kits. Serum C-reactive protein (CRP) concentration was measured by the turbidimetric method. OPN (p = 0.001) and CRP (p < 0.001) concentrations were significantly higher in lung cancer patients compared to controls whereas TNF-α concentrations were similar in cancer and control groups (p = 0.063). There were 33 NSCLC patients (52.4%) with weight loss. Serum OPN concentration was found to be higher in this weight-losing group (p = 0.042). CRP concentration was also higher in the weight-losing group but the difference was not statistically significant (p = 0.246). TNF-α concentrations were similar in both subgroups (p = 0.094). In correlation tests, there was a positive correlation between OPN and CRP (r = 0.299, p = 0.044), but no correlation was detected between OPN and TNF-α (r = − 0.009, p = 0.930). A negative correlation was detected between OPN and BMI (r = − 0.246, p = 0.048). In addition to being an indicator of systemic inflammation in lung cancer patients, osteopontin may also be an indicator of weight loss.

Secreted osteopontin is highly polymerized in human airways and fragmented in asthmatic airway secretions

BACKGROUND

Osteopontin (OPN) is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family and a cytokine with diverse biologic roles. OPN undergoes extensive post-translational modifications, including polymerization and proteolytic fragmentation, which alters its biologic activity. Recent studies suggest that OPN may contribute to the pathogenesis of asthma.

METHODOLOGY

To determine whether secreted OPN (sOPN) is polymerized in human airways and whether it is qualitatively different in asthma, we used immunoblotting to examine sOPN in bronchoalveolar lavage (BAL) fluid samples from 12 healthy and 21 asthmatic subjects (and in sputum samples from 27 healthy and 21 asthmatic subjects). All asthmatic subjects had mild to moderate asthma and abstained from corticosteroids during the study. Furthermore, we examined the relationship between airway sOPN and cellular inflammation.

PRINCIPAL FINDINGS

We found that sOPN in BAL fluid and sputum exists in polymeric, monomeric, and cleaved forms, with most of it in polymeric form. Compared to healthy subjects, asthmatic subjects had proportionately less polymeric sOPN and more monomeric and cleaved sOPN. Polymeric sOPN in BAL fluid was associated with increased alveolar macrophage counts in airways in all subjects.

CONCLUSIONS

These results suggest that sOPN in human airways (1) undergoes extensive post-translational modification by polymerization and proteolytic fragmentation, (2) is more fragmented and less polymerized in subjects with mild to moderate asthma, and (3) may contribute to recruitment or survival of alveolar macrophages.

Osteopontin and endostatin concentrations in peripheral blood of patients with adrenal tumors undergoing unilateral adrenalectomy

Peripheral blood osteopontin (OPN) and endostatin (END) levels were studied in 35 patients with adrenal cortex tumors and 10 patients with pheochromocytoma before unilateral adrenalectomy, as well as in 10 healthy subjects (controls). Thirty days after surgery, OPN and END were evaluated again in 16 patients with adrenal cortex tumors and 4 female patients with pheochromocytoma. Before surgery, OPN blood concentrations increased in the group of patients with adrenal cortex carcinomas as compared to controls (p < 0.001) and the group with Conn syndrome (p < 0.05); they did not change after surgery. Before adrenalectomy, OPN blood levels in pheochromocytoma patients were also lower than in Conn syndrome subjects (p < 0.05). After adrenalectomy, the normal concentrations of END decreased only in the group of patients with hormonally inactive cortical adenomas (p < 0.05). We were unable to demonstrate any relationships between removed tumor volumes and OPN or END blood levels.

Osteopontin modulates inflammation, mucin production, and gene expression signatures after inhalation of asbestos in a murine model of fibrosis

Inflammation and lung remodeling are hallmarks of asbestos-induced fibrosis, but the molecular mechanisms that control these events are unclear. Using laser capture microdissection (LCM) of distal bronchioles in a murine asbestos inhalation model, we show that osteopontin (OPN) is up-regulated by bronchiolar epithelial cells after chrysotile asbestos exposures. In contrast to OPN wild-type mice (OPN(+/+)) inhaling asbestos, OPN null mice (OPN(-/-)) exposed to asbestos showed less eosinophilia in bronchoalveolar lavage fluids, diminished lung inflammation, and decreased mucin production. Bronchoalveolar lavage fluid concentrations of inflammatory cytokines (IL-1β, IL-4, IL-6, IL-12 subunit p40, MIP1α, MIP1β, and eotaxin) also were significantly less in asbestos-exposed OPN(-/-) mice. Microarrays performed on lung tissues from asbestos-exposed OPN(+/+) and OPN(-/-) mice showed that OPN modulated the expression of a number of genes (Col1a2, Timp1, Tnc, Eln, and Col3a1) linked to fibrosis via initiation and cross talk between IL-1β and epidermal growth factor receptor-related signaling pathways. Novel targets of OPN identified include genes involved in cell signaling, immune system/defense, extracellular matrix remodeling, and cell cycle regulation. Although it is unclear whether the present findings are specific to chrysotile asbestos or would be observed after inhalation of other fibers in general, these results highlight new potential mechanisms and therapeutic targets for asbestosis and other diseases (asthma, smoking-related interstitial lung diseases) linked to OPN overexpression.

Systemic blood osteopontin, endostatin, and E-selectin concentrations after vertical banding surgery in severely obese adults

BACKGROUND

Obesity is associated with endothelial dysfunction and increased inflammation as well as with expansion of the capillary bed in regional adipose deposits, and a balance between these factors is involved in angiogenesis. Osteopontin (OPN) is a proinflammatory cytokine involved in regulating immune processes and mediating chronic inflammation. Its level is usually elevated in the plasma and adipose tissue of obese subjects. E-selectin, an adhesion molecule which is released by dysfunctional endothelial cells, is believed to be a marker of an early atherosclerotic process. Endostatin (END), an angiogenesis inhibitor, is present in the blood of obese subjects. The most effective treatment to achieve weight loss in morbidly obese subjects is bariatric surgery. The aim of the study was to evaluate and compare the circulating concentrations of OPN, E-selectin and END as well as the insulin resistance (HOMA-IR) of severely obese patients with metabolic syndrome before and after vertical banded gastroplasty (VBG).

MATERIAL AND METHODS

The test cohorts comprised eight males and 20 females (total 28 patients) aged from 20 to 59 years with simple obesity and the presence of metabolic syndrome, both before and 3, 6, 12, 24 months after bariatric surgery (six patients were also checked after 36 and four after 48 months).

RESULTS

Bariatric surgery significantly reduced (over 24 months) body weight, BMI, waist circumference, HOMA-IR and blood concentrations of CRP. Plasma OPN gradually increased after VBG and E-selectin in systemic blood decreased. We did not observe any differences in END concentrations from 12 to 48 months after surgery.

CONCLUSION

VBG improves metabolic syndrome parameters, decreases E-selectin and gradually increases OST blood concentrations but it does not have any significant influence on END levels.

Osteopontin and allergic disease: pathophysiology and implications for diagnostics and therapy

Osteopontin (OPN) is a phosphoglycoprotein that is expressed by various immune cells in a secreted and intracellular form. It has cytokine, chemotactic and cell signaling functions enhancing Th1 and Th17 immunity and protects against apoptosis. Recent studies found OPN to be modulatory in cell-mediated and immediate-type allergic diseases. In allergic asthma, OPN enhances sensitization but downmodulates Th2-driven IL-4-dominated inflammation. The finding that OPN expression is augmented during specific immunotherapy supports a Th2 suppressive effect of OPN. In Th1-driven delayed-type allergy, such as allergic contact dermatitis, OPN supports dendritic cell migration and IL-12 expression and is secreted by T effector cells and keratinocytes, augmenting Th1-mediated allergy and supporting disease chronification. There are numerous missing links as to how OPN variants modulate allergic inflammation through different OPN receptors. OPN research in allergy is an interesting, rapidly expanding field that has high potential for translational research.

Novel murine model of chronic granulomatous lung inflammation elicited by carbon nanotubes

Lung granulomas are associated with numerous conditions, including inflammatory disorders, exposure to environmental pollutants, and infection. Osteopontin is a chemotactic cytokine produced by macrophages, and is implicated in extracellular matrix remodeling. Furthermore, osteopontin is up-regulated in granulomatous disease, and osteopontin null mice exhibit reduced granuloma formation. Animal models currently used to investigate chronic lung granulomatous inflammation bear a pathological resemblance, but lack the chronic nature of human granulomatous disease. Carbon nanoparticles are generated as byproducts of combustion. Interestingly, experimental exposures to carbon nanoparticles induce pulmonary granuloma-like lesions. However, the recruited cellular populations and extracellular matrix gene expression profiles within these lesions have not been explored. Because of the rapid resolution of granulomas in current animal models, the mechanisms responsible for persistence have been elusive. To overcome the limitations of previous models, we investigated whether a model using multiwall carbon nanoparticles would resemble chronic human lung granulomatous inflammation. We hypothesized that pulmonary exposure to multiwall carbon nanoparticles would induce granulomas, elicit a macrophage and T-cell response, and mimic other granulomatous disorders with an up-regulation of osteopontin. This model demonstrates: (1) granulomatous inflammation, with macrophage and T-cell infiltration; (2) resemblance to the chronicity of human granulomas, with persistence up to 90 days; and (3) a marked elevation of osteopontin, metalloproteinases, and cell adhesion molecules in granulomatous foci isolated by laser-capture microdissection and in alveolar macrophages from bronchoalveolar lavage. The establishment of such a model provides an important platform for mechanistic studies on the persistence of granuloma.

Distinct severe acute respiratory syndrome coronavirus-induced acute lung injury pathways in two different nonhuman primate species

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), caused by influenza A virus H5N1 and severe acute respiratory syndrome coronavirus (SARS-CoV), supposedly depend on activation of the oxidative-stress machinery that is coupled with innate immunity, resulting in a strong proinflammatory host response. Inflammatory cytokines, such as interleukin 1β (IL-1β), IL-8, and IL-6, play a major role in mediating and amplifying ALI/ARDS by stimulating chemotaxis and activation of neutrophils. To obtain further insight into the pathogenesis of SARS-CoV-associated ALI, we compared SARS-CoV infections in two different nonhuman primate species, cynomolgus macaques and African green monkeys. Viral titers in the upper and lower respiratory tract were not significantly different in SARS-CoV-infected macaques and African green monkeys. Inflammatory cytokines that play a major role in mediating and amplifying ALI/ARDS or have neutrophil chemoattractant activity, such as IL-6, IL-8, CXCL1, and CXCL2, were, however, induced only in macaques. In contrast, other proinflammatory cytokines and chemokines, including osteopontin and CCL3, were upregulated in the lungs of African green monkeys to a significantly greater extent than in macaques. Because African green monkeys developed more severe ALI than macaques, with hyaline membrane formation, some of these differentially expressed proinflammatory genes may be critically involved in development of the observed pathological changes. Induction of distinct proinflammatory genes after SARS-CoV infection in different nonhuman primate species needs to be taken into account when analyzing outcomes of intervention strategies in these species.

Cardiovascular and inflammatory effects of intratracheally instilled ambient dust from Augsburg, Germany, in spontaneously hypertensive rats (SHRs)

Rationale

Several epidemiological studies associated exposure to increased levels of particulate matter in Augsburg, Germany with cardiovascular mortality and morbidity. To elucidate the mechanisms of cardiovascular impairments we investigated the cardiopulmonary responses in spontaneously hypertensive rats (SHR), a model for human cardiovascular diseases, following intratracheal instillation of dust samples from Augsburg.

Methods

250 μg, 500 μg and 1000 μg of fine ambient particles (aerodynamic diameter <2.5 μm, PM_2.5-AB) collected from an urban background site in Augsburg during September and October 2006 (PM_2.5 18.2 μg/m³, 10,802 particles/cm³) were instilled in 12 months old SHRs to assess the inflammatory response in bronchoalveolar lavage fluid (BALF), blood, lung and heart tissues 1 and 3 days post instillation. Radio-telemetric analysis was performed to investigate the cardiovascular responses following instillation of particles at the highest dosage based on the inflammatory response observed.

Results

Exposure to 1000 μg of PM_2.5-AB was associated with a delayed increase in delta mean blood pressure (ΔmBP) during 2^nd-4^th day after instillation (10.0 ± 4.0 vs. -3.9 ± 2.6 mmHg) and reduced heart rate (HR) on the 3^rd day post instillation (325.1 ± 8.8 vs. 348.9 ± 12.5 bpm). BALF cell differential and inflammatory markers (osteopontin, interleukin-6, C-reactive protein, and macrophage inflammatory protein-2) from pulmonary and systemic level were significantly induced, mostly in a dose-dependent way. Protein analysis of various markers indicate that PM_2.5-AB instillation results in an activation of endothelin system (endothelin1), renin-angiotensin system (angiotensin converting enzyme) and also coagulation system (tissue factor, plasminogen activator inhibitor-1) in pulmonary and cardiac tissues during the same time period when alternation in ΔmBP and HR have been detected.

Conclusions

Our data suggests that high concentrations of PM_2.5-AB exposure triggers low grade PM mediated inflammatory effects in the lungs but disturbs vascular homeostasis in pulmonary tissues and on a systemic level by affecting the renin angiotensin system, the endothelin system and the coagulation cascade. These findings are indicative for promotion of endothelial dysfunction, atherosclerotic lesions, and thrombogeneis and, thus, provide plausible evidence that susceptible-predisposed individuals may develop acute cardiac events like myocardial infarction when repeatedly exposed to high pollution episodes as observed in epidemiological studies in Augsburg, Germany.

Osteopontin: an effector and an effect of tumor metastasis

Osteopontin (OPN) is a matricellular protein that is produced by multiple tissues in our body and is most abundant in bone. It is also produced by cancer cells and plays a determinative role in the growth, progression and metastasis of cancer. Clinically, OPN has been reported to be upregulated in tumor cells per se; this is also reflected by increased levels of OPN in the circulation. Thus, increased OPN levels the plasma are an effect of tumor growth and progression. Functionally, high OPN levels are determinative of higher incidence of bone metastases in mouse models and are clinically correlated with metastatic bone disease and bone resorption in advanced breast cancer patients. Several research efforts have been made to therapeutically target and inhibit the activities of OPN. In this article we have reviewed OPN in its role as an effector of critical steps in tumor progression and metastasis, with a particular emphasis on its role in facilitating bone metastasis of breast cancer. We have also addressed the role of the host-derived OPN in influencing the malignant behavior of the tumor cells.

An in vitro assessment of a cell-containing collagenous extracellular matrix-like scaffold for bone tissue engineering

Extracellular matrix (ECM) consists of a complex mixture of macromolecules such as collagens, proteoglycans, glycoproteins, and elastic fibers. ECM is essential to preserving tissue architecture, signaling to cells, and regulating calcification in mineralized tissues. Osteoblasts in culture secrete and assemble an extensive ECM rich in type I collagen, and other noncollagenous proteins that can be mineralized. Three-dimensional matrix models can be used in vitro to most appropriately resemble the geometry and biochemistry of natural ECMs. In the present study, MC3T3-E1 mouse calvarial preosteoblasts were cultured within a dense three-dimensional collagenous ECM-like scaffold produced through the method of plastic compression. Plastic compression rapidly produces scaffolds of collagen density approaching native tissue levels with enhanced biomechanical properties while maintaining the viability of resident cells. The proliferation, morphology, and gene expression of seeded MC3T3s, as well as collagen production and matrix mineralization, were investigated for up to 7 weeks in culture. Soluble collagen secretion ranged in concentration from 5 to 30 microg/mL over a 24-h period, concomitant with a steady rate of collagen mRNA expression. Expression of osteogenic markers such as tissue-nonspecific alkaline phosphatase (Alpl), bone sialoprotein (Bsp), and osteopontin (Opn) examined by biochemical assay and reverse transcription-polymerase chain reaction demonstrated cell differentiation. Pericellular voids of ECM around cells, together with evidence of MMP13 mRNA expression, suggested matrix remodeling. Ultrastructural analyses, X-ray microanalysis, micro-computed tomography, as well as Fourier-transform infrared and imaging all confirmed the formation of a calcium-phosphate mineral phase within the fibrillar collagen matrix. In conclusion, preosteoblastic MC3T3 cells seeded within an ECM-like dense collagen scaffold secrete matrix proteins and induce scaffold mineralization in a manner potentially appropriate for bone tissue engineering uses.

Local Atherosclerotic Plaques Are a Source of Prognostic Biomarkers for Adverse Cardiovascular Events

Objective— Atherosclerotic cardiovascular disease is a major burden to health care. Because atherosclerosis is considered a systemic disease, we hypothesized that one single atherosclerotic plaque contains ample molecular information that predicts future cardiovascular events in all vascular territories.

Methods and Results— AtheroExpress is a biobank collecting atherosclerotic lesions during surgery, with a 3-year follow-up. The composite primary outcome encompasses all cardiovascular events and interventions, eg, cardiovascular death, myocardial infarction, stroke, and endovascular interventions. A proteomics search identified osteopontin as a potential plaque biomarker. Patients undergoing carotid surgery (n=574) served as the cohort in which plaque osteopontin levels were examined in relation to their outcome during follow-up and was validated in a cohort of patients undergoing femoral endarterectomy (n=151). Comparing the highest quartile of carotid plaque osteopontin levels with quartile 1 showed a hazard ratio for the primary outcome of 3.8 (95% confidence interval, 2.6–5.9). The outcome did not change after adjustment for plaque characteristics and traditional risk factors (hazard ratio, 3.5; 95% confidence interval, 2.0–5.9). The femoral validation cohort showed a hazard ratio of 3.8 (95% confidence interval 2.0 to 7.4) comparing osteopontin levels in quartile 4 with quartile 1.

Conclusion— Plaque osteopontin levels in single lesions are predictive for cardiovascular events in other vascular territories. Local atherosclerotic plaques are a source of prognostic biomarkers with a high predictive value for secondary manifestations of atherosclerotic disease.

ApoE-deficient mice on cholate-containing high-fat diet reveal a pathology similar to lung sarcoidosis

Sarcoidosis is a chronic disease of unknown etiology characterized by the formation of non-necrotizing epithelioid granulomas in various organs, especially in the lungs. The lack of an adequate animal model reflecting the pathogenesis of the human disease is one of the major impediments in studying sarcoidosis. In this report, we describe ApoE-/- mice on a cholate-containing high-fat diet that exhibit granulomatous lung inflammation similar to human sarcoidosis. Histological analysis revealed well-defined and non-necrotizing granulomas in about 40% of mice with the highest number of granulomas after 16 weeks on a cholate-containing high-fat diet. Granulomas contained CD4+ and CD8+ T cells, and the majority of the cells in granulomas showed immunoreactivity for the macrophage marker Mac-3. Cells with morphological features of epithelioid cells expressed angiotensin-converting enzyme, osteopontin, and cathepsin K, all characteristics of epithelioid and giant cells in granulomas of human sarcoidosis. Giant cells and nonspecific inclusions such as Schaumann's bodies and crystalline deposits were also detected in some lungs. Granulomatous inflammation resulted in progressive pulmonary fibrosis. Removal of cholate from the diet prevented the formation of lung granulomas. The observed similarities between the analyzed mouse lung granulomas and granulomas of human sarcoidosis, as well as the chronic disease character leading to fibrosis, suggest that this mouse model might be a useful tool to study sarcoidosis.

Reduction of elevated plasma osteopontin levels with resection of non-small-cell lung cancer

PURPOSE Plasma osteopontin (OPN) levels in advanced non-small-cell lung cancer (NSCLC) correlate with therapeutic response and survival, but the utility of plasma OPN for diagnosis and monitoring of early-stage NSCLC has not been investigated. We hypothesize that plasma OPN levels are elevated in early-stage NSCLC and decrease with resection. PATIENTS AND METHODS Presurgery plasma OPN levels (in ng/mL) were measured by enzyme-linked immunosorbent assay (ELISA) in a discovery set of 60 patients with early-stage NSCLC and were compared with data from 56 cancer-free smokers. Presurgery OPN was validated in an independent cohort of 96 patients with resectable NSCLC. The presurgery levels in the latter cohort were compared with matched postsurgery levels. Perioperative OPN levels were correlated with demographics, tumor characteristics, and perioperative events. OPN was monitored during follow-up. Results Discovery set presurgery NSCLC OPN (271 +/- 31 ng/mL) was higher than smokers (40 +/- 2 ng/mL; P = .001). Presurgery OPN was similar in the NSCLC validation cohort (324 ng/mL +/- 20 ng/mL; P = .134). Postsurgery OPN (256 ng/mL +/- 21 ng/mL) measured at mean of 9.8 weeks (range, 2 to 46 weeks) was lower than presurgery OPN (P = .005). Time from surgery significantly impacted postsurgery OPN: OPN < or = 6 weeks postsurgery (303 n/mL +/- 26 ng/mL) was higher than OPN greater than 6 weeks postsurgery (177 ng/mL +/- 29 ng/mL; P = .003). Multivariate analysis noted correlations between albumin and creatinine to presurgery OPN and use of thoracotomy to postsurgery OPN. Recurrence rate was 5% at 29 weeks mean follow-up. OPN at recurrence was elevated from postsurgery nadir. CONCLUSION Plasma OPN levels are elevated in early-stage NSCLC. They are reduced after resection and appear to increase with recurrence. Plasma OPN may have utility as a biomarker in early-stage NSCLC.

The bile acid sensor farnesoid X receptor is a modulator of liver immunity in a rodent model of acute hepatitis

Immune-mediated liver diseases including autoimmune and viral hepatitis are a major health problem worldwide. In this study, we report that activation of the farnesoid X receptor (FXR), a member of the ligand-activated nuclear receptor superfamily and bile sensor highly expressed in the liver, attenuates liver injury in a model of autoimmune hepatitis induced by Con A. We found that FXR gene ablation results in a time-dependent increase of liver expression (up to 20-fold in a 9-mo-old mouse) of osteopontin, a NKT cell-derived extracellular matrix protein and immunoregulatory cytokine. In comparison to wild-type, FXR(-/-) mice are more susceptible to Con A-induced hepatitis and react to Con A administration by an unregulated production of osteopontin. Administering wild-type mice with a synthetic FXR agonist attenuated Con A-induced liver damage and liver expression of the osteopontin gene. By in vitro studies, we found that FXR is expressed by primarily isolated NKT cells and its ablation favors ostepontin production in response to Con A. Chromatin immunoprecipitation assay and coimmunoprecipitation experiments demonstrate that the short heterodimer partner (SHP), a nuclear receptor and FXR target, was expressed by NKT cell hybridomas and increased in response to FXR activation. FXR activates SHP that interacts with and inhibits c-Jun binding to the osteopontin promoter. These data indicate that in NKT cells, FXR activation causes a SHP-mediated inhibition of osteopontin production. These data support the notion that the bile acid sensor FXR regulates the activation of liver NKT cells.

Pulmonary toxicity of multi-walled carbon nanotubes (Baytubes) relative to alpha-quartz following a single 6h inhalation exposure of rats and a 3 months post-exposure period

Manufactured multi-walled carbon nanotubes (MWCNT) have attracted a great deal of attention due to their unique structural, chemical, and physical characteristics. This study utilized a 1x 6h inhalation exposure protocol followed by a 3 months post-exposure period. Wistar rats were nose-only exposed to 11 and 241 mg/m(3) MWCNT (Baytubes) of respirable, solid aerosol. MWCNT depleted of residual metals (depletion from 0.53% to 0.12% Co) were compared at 11 mg/m(3). Rats similarly exposed to air and alpha-quartz (248 mg/m(3)) served as negative and positive controls, respectively. Pulmonary response was characterized by bronchoalveolar lavage (BAL), lung histopathology, organ burden determinations, and gene expression analyses of lung homogenates with emphasis on extracellular matrix components. This acute inhalation exposure protocol was suitable to characterize and distinguish acute deposition-related effects from the long-term sequelae of retained MWCNT. Subtle differences in acute pulmonary toxic potency due to differences in metal contaminations could be revealed by this protocol. Consistent with the long retention halftime of poorly soluble particles, even short-term inhalation studies may require post-exposure periods of at least 3 months to reveal MWCNT-specific dispositional and toxicological characteristics relative to alpha-quartz. Distinct differences in the time course of pulmonary inflammation of MWCNT and alpha-quartz could be demonstrated. Transcriptomics proved to be a useful tool to analyze the etiopathology of collagen detected by BAL and histopathology. In summary, the pulmonary inflammogenicity following exposure to MWCNT was concentration-dependent with evidence of regression over time. Conversely, alpha-quartz resulted in progressive changes over time. The time course of pulmonary inflammation associated with retained MWCNT was independent on the concentration of residual cobalt. This supports the conclusion that the predominant response to inhaled MWCNT is principally related to the assemblage structure and not catalyst impurities (if in the range of < or = 0.5%).

beta6 Integrin subunit deficiency alleviates lung injury in a mouse model of bronchopulmonary dysplasia

Pulmonary inflammation is associated with the development of bronchopulmonary dysplasia in premature infants. We have previously shown that perinatal pulmonary expression of human IL-1beta is sufficient to cause a lung disease similar to bronchopulmonary dysplasia, characterized by inflammation, impaired alveolarization, poor postnatal growth, and increased mortality in infant mice. The alphavbeta6 integrin plays a critical role in regulating inflammation in the adult lung. To study the role of the beta6 integrin subunit in neonatal inflammatory lung disease, we compared the pulmonary development in IL-1beta-expressing infant mice with wild-type or null beta6 integrin loci. Absence of the beta6 integrin subunit decreased the mortality and improved the postnatal growth of IL-1beta-expressing pups. The disrupted alveolar development of IL-1beta-expressing mice was improved by beta6 integrin deficiency. IL-1beta-expressing beta6(-/-) pups had shorter alveolar chord length and thinner alveolar walls than IL-1beta-expressing beta6(+/+) pups. In addition, the absence of the beta6 integrin subunit reduced IL-1beta-induced neutrophil and macrophage infiltration into the alveolar spaces. beta6 integrin subunit deficiency suppressed inflammation and goblet cell hyperplasia in the airways and alleviated airway remodeling in IL-1beta-expressing mice. The expression of the chemoattractant proteins, keratinocyte-derived chemokine, macrophage-inflammatory protein-2, calgranulin A, and calgranulin B, of osteopontin, and of the chitinase-like lectins, Ym1 and Ym2, was lower in IL-1beta-expressing beta6(-/-) than in IL-1beta-expressing beta6(+/+) mice. We conclude that absence of the beta6 integrin subunit protects the infant murine lung against IL-1beta-induced inflammation and injury.

Abnormal bone remodeling process is due to an imbalance in the receptor activator of nuclear factor-kappaB ligand (RANKL)/osteoprotegerin (OPG) axis in patients with solid tumors metastatic to the skeleton

The role of receptor activator of nuclear factor-kappaB ligand (RANKL)/osteoprotegerin (OPG) system, and osteopontin (OPN) was studied in patients with solid tumors metastatic to the bone in relation to the type of malignancy and the neoplastic burden to the skeleton. Levels of soluble RANKL (sRANKL), OPG and OPN were assessed in 61 patients with breast, lung and prostate cancer with newly-diagnosed metastasis to the bone, in parallel with bone resorption [C-telopeptide of type-I collagen (CTX), tartrate-resistant acid phosphatase-5b (TRACP-5b)] and bone formation markers [bone-alkaline phosphatase (bALP), osteocalcin (OC), and C-terminal propeptide of collagen type-I (CICP)]. Patients had elevated serum levels of sRANKL, OPG, OPN, TRACP-5b, and bALP, and reduced OC levels compared to controls. OPG correlated with the extent of metastatic bone burden. Patients with breast and lung cancer shared increased levels of sRANKL, OPG, and OPN whereas prostate cancer patients had elevated values of OPG and bALP only. These results suggest that patients with solid tumors metastatic to the bone have severe disruption of the sRANKL/OPG axis. Breast and lung cancer seem to exert their osteolytic action through upregulation of the sRANKL/OPG system and OPN, whereas prostate cancer seems to provoke profound elevation of OPG levels only, thus leading to increased osteoblastic activity.

Osteopontin: role in extracellular matrix deposition and myocardial remodeling post-MI

Remodeling after myocardial infarction (MI) associates with left ventricular (LV) dilation, decreased cardiac function and increased mortality. The dynamic synthesis and breakdown of extracellular matrix (ECM) proteins play a significant role in myocardial remodeling post-MI. Expression of osteopontin (OPN) increases in the heart post-MI. Evidence has been provided that lack of OPN induces LV dilation which associates with decreased collagen synthesis and deposition. Inhibition of matrix metalloproteinases, key players in ECM remodeling process post-MI, increased ECM deposition (fibrosis) and improved LV function in mice lacking OPN after MI. This review summarizes--1) signaling pathways leading to increased expression of OPN in the heart; 2) the alterations in the structure and function of the heart post-MI in mice lacking OPN; and 3) mechanisms involved in OPN-mediated ECM remodeling post-MI.

Osteopontin and the skin: multiple emerging roles in cutaneous biology and pathology

Osteopontin (OPN) is a glycoprotein expressed by various tissues and cells. The existence of variant forms of OPN as a secreted (sOPN) and intracellular (iOPN) protein and its modification through post-translational modification and proteolytic cleavage explain its broad range of functions. There is increasing knowledge which receptors OPN isoforms can bind to and which signaling pathways are activated to mediate different OPN functions. sOPN interacts with integrins and CD44, mediates cell adhesion, migration and tumor invasion, and has T helper 1 (Th1) cytokine functions and anti-apoptotic effects. iOPN has been described to regulate macrophage migration and interferon-alpha secretion in plasmacytoid dendritic cells. Both sOPN and iOPN, through complex functions for different dendritic cell subsets, participate in the regulation of Th cell lineages, among them Th17 cells. For skin disease, OPN from immune cells and tumor cells is of pathophysiological relevance. OPN is secreted in autoimmune diseases such as lupus erythematosus, and influences inflammation of immediate and delayed type allergies and granuloma formation. We describe that OPN is overexpressed in psoriasis and propose a model to study OPN function in psoriatic inflammation. Through cytokine functions, OPN supports immune responses against Mycobacteria and viruses such as herpes simplex virus. OPN is also implicated in skin tumor progression. Overexpression of OPN influences invasion and metastasis of melanoma and squamous cell carcinoma cells, and OPN expression in melanoma is a possible prognostic marker. As OPN protein preparations and anti-OPN antibodies may be available in the near future, in-depth knowledge of OPN functions may open new therapeutic approaches for skin diseases.

Effects of corticosteroids on osteopontin expression in a murine model of allergic asthma

BACKGROUND

Osteopontin (OPN) contributes to the development of T helper 1 (Th1)-mediated immunity and Th1-associated diseases. However, the role of OPN in bronchial asthma is unclear. Corticosteroids reduce airway inflammation, as reflected by the low eosinophil and T-cell counts, and the low level of cytokine expression. We investigated OPN production and the inhibitory effects of corticosteroids on OPN production in a murine model of allergic asthma.

METHODS

BALB/c mice were sensitized by intraperitoneal injections of ovalbumin (OVA) with alum. Some mice received daily injections of dexamethasone (DEX) or phosphate-buffered saline for 1 week. All OVA-challenged mice were exposed to aerosolized 1% OVA for 30 min an hour after these injections. After the OVA challenge, the mice were killed, and bronchoalveolar lavage (BAL) fluid and lung tissue were examined.

RESULTS

The levels of OPN protein in BAL fluid and OPN mRNA in lung tissue increased after OVA challenge. Most OPN-expressing cells were CD11c+ cells and some were T cells. DEX decreased the levels of OPN protein in the BAL fluid, and those of OPN mRNA and OPN protein in lung tissue.

CONCLUSIONS

OPN may play an important role in allergic bronchial asthma. Corticosteroids inhibit OPN production in mice with allergic asthma. The beneficial effect of corticosteroids in bronchial asthma is partly due to their inhibitory effects on OPN production.

Osteopontin is upregulated in malignant and inflammatory pleural effusions

BACKGROUND AND OBJECTIVE

Osteopontin (OPN) is an important mediator of inflammation and cancer progression. In the present study, we asked whether pleural fluid (PF) and serum OPN concentrations differed between patients with pleural effusions of different aetiologies, and whether assessment of OPN levels was useful for diagnostic purposes.

METHODS

One hundred and nine consecutive patients with pleural effusions of different aetiologies were recruited prospectively during daily clinics. OPN levels were measured by ELISA.

RESULTS

PF OPN levels were 10-fold higher in exudates than in transudates and were significantly correlated with markers of pleural inflammation and vascular hyper-permeability, such as PF/serum LDH or protein ratios, PF protein and PF vascular endothelial growth factor levels. Patients with malignant pleural effusions had higher PF and lower serum OPN concentrations than those with benign disease. The diagnostic accuracies of PF and PF/serum OPN for malignancy were 71.5% (95% CI: 64-80) and 70.6% (95% CI: 62-80), respectively.

CONCLUSIONS

OPN levels were elevated in exudative pleural effusions, as compared with the levels in blood or transudative pleural effusions. While PF and PF/serum OPN were higher in patients with malignancies, the diagnostic accuracy of the tests was not sufficient to permit routine use in clinical practice.

Essential role of osteopontin in smoking-related interstitial lung diseases

Smoking-related interstitial lung diseases are characterized by the accumulation of macrophages and Langerhans cells, and fibrotic remodeling, which are linked to osteopontin (OPN) expression. Therefore, OPN levels were investigated in bronchoalveolar lavage (BAL) cells in 11 patients with pulmonary Langerhans cell histiocytosis (PLCH), 15 patients with desquamative interstitial pneumonitis (DIP), 10 patients with idiopathic pulmonary fibrosis, 5 patients with sarcoidosis, 13 otherwise healthy smokers, and 19 non-smoking controls. Furthermore, OPN overexpression was examined in rat lungs using adenoviral gene transfer. We found that BAL cells from patients with either PLCH or DIP spontaneously produced abundant amounts of OPN. BAL cells from healthy smokers produced 15-fold less OPN, and those cells from non-smoking healthy volunteers produced no OPN. BAL cells from patients with either idiopathic pulmonary fibrosis or sarcoidosis produced significantly less OPN, as compared with patients with PLCH. These data were confirmed by immunochemistry. Nicotine stimulation increased production of both OPN and granulocyte-macrophage colony stimulating factor by alveolar macrophages from smokers. Nicotinic acetylcholine receptor expression resembled the pattern of spontaneous OPN production and was dramatically increased in both PLCH and DIP. OPN overexpression in rat lungs induced lesions similar to PLCH with marked alveolar and interstitial accumulation of Langerhans cells. Our findings suggest a pathogenetic role of increased OPN production in both PLCH and DIP by promoting the accumulation of macrophages and Langerhans cells.

Serum bone turnover markers may be involved in the metastatic potential of lung cancer patients

The aim of this study was to investigate several bone markers in Non-Small Cell Lung (NSCLC) and Small Cell Lung (SCLC) patients experiencing or not secondary bony disease. Fasting serum levels of bone formation, bone resorption, and osteoclastogenesis markers were determined in 22 NSCLC patients with bone metastases, 18 without bone metastasis, and 28 SCLC patients. A total of 29 healthy volunteers were also included in the study. Decreased osteocalcin (OC) serum levels and increased osteopontin and ligand of the receptor of nuclear factor kB (RANKL) serum levels were detected in NCSLC patients with bone metastases while increased C-terminal cross-linking telopeptide of type I collagen and increased RANKL/OPG (osteoprotegerin) ratio were detected in SCLC patients. Increased serum levels of OPG were observed in all lung cancer patients. OPG may be actively involved in the development of lung cancer metastasis. Furthermore, OC, OPN, and RANKL in NSCLC and CTX and RANKL in SCLC patients may also have a broader role in the pathogenesis and spread of lung cancer. They also provide useful information in identifying the group of patients that may benefit from a more rigorous treatment.

Osteopontin is not crucial to protective immunity during murine tuberculosis

Upon infection with Mycobacterium (M.) tuberculosis, the development of a strong T helper 1 (Th1)-mediated adaptive immune response is considered as being most important for containment of the infection. Osteopontin (OPN) is a phosphorylated glycoprotein that is chemotactic for inflammatory cells and has been implicated in the induction of Th1 responses and granulomatous disease. We tested the hypothesis that OPN facilitates protective immunity during M. tuberculosis infection using wild-type (WT) and OPN knockout (KO) mice in a model of pulmonary tuberculosis. OPN expression was up-regulated in alveolar macrophages and lymphoid cells during M. tuberculosis infection. There were no significant differences in bacterial outgrowth, inflammation or recruitment of lymphocytes, macrophages and polymorphonuclear cells in the lungs after 2 and 5 weeks of infection. However, the numbers of CD4(+) and CD8(+) T cells were reduced in the absence of OPN 5 weeks after infection. Similar concentrations of cytokine were observed in lungs from both WT mice and OPN KO mice; however, there was a trend towards decreased levels of interferon-gamma (IFN-gamma) in OPN KO mice 5 weeks after infection. Despite an unaltered immune response in the early phase of tuberculosis, OPN KO mice had a modest survival advantage. Of note, both pulmonary bacterial loads and lung inflammation were reduced in these mice 31 weeks after infection. These data suggest that OPN is not crucial for protective immunity upon M. tuberculosis infection and during the late phase of tuberculosis may even be detrimental for the host.

Osteopontin induces airway remodeling and lung fibroblast activation in a murine model of asthma

Airway remodeling is a central feature of asthma; however, the mechanisms underlying its development have not been fully elucidated. We have demonstrated that osteopontin, an inflammatory cytokine and an extracellular matrix glycoprotein with profibrotic properties, is up-regulated in a murine model of allergen-induced airway remodeling. In the present study, we determined whether osteopontin plays a functional role in airway remodeling. Osteopontin (OPN)-deficient (OPN(-/-)) and wild-type mice were sensitized and exposed to inhaled ovalbumin (OVA) or saline for 5 weeks. Collagen production, peribronchial smooth muscle area, mucus-producing cell number, and bronchoalveolar cell counts were assessed. The functional behavior and phenotype of lung fibroblasts from OVA-treated OPN(-/-) and from wild-type mice were studied using ex vivo cultures. OVA-treated OPN(-/-) mice exhibited reduced lung collagen content, smooth muscle area, mucus-producing cells, and inflammatory cell accumulation as compared with wild-type mice. Reduced matrix metalloproteinase-2 activity and expression of transforming growth factor-beta1 and vascular endothelial growth factor were observed in OVA-treated OPN(-/-) mice. Lung fibroblasts from OVA-treated OPN(-/-) mice showed reduced proliferation, migration, collagen deposition, and alpha-smooth muscle actin expression in comparison with OVA-treated wild-type lung fibroblasts. Thus, OPN is key for the development of allergen-induced airway remodeling in mice. In response to allergen, OPN induces the switching of lung fibroblasts to a pro-fibrogenic myofibroblast phenotype.

Distinct regulatory profiles of interleukins and chemokines in response to cigarette smoke condensate in normal human bronchial epithelial (NHBE) cells

Bronchial epithelium is frequently exposed to air pollutants, and it is hypothesized that these cells elicit inflammatory responses as early elements in pulmonary defense. Our purpose was to evaluate changes in messenger RNA levels of 84 genes representing cytokines and receptors over a repetitive-exposure time course to further define the inflammatory responses associated with mainstream cigarette smoke (MSS) exposure in an in vitro lung model. Normal human bronchial epithelial cells were treated with mainstream cigarette smoke condensate (CSC) prepared from Kentucky 2R4F cigarettes (60 microg total particulate matter/mL media, 0.2% dimethylsulfoxide), and examined by quantitative real-time polymerase chain reaction. Applications of CSC were designed in seven groups to test immediate, early, intermediate, and late responses evaluated at the end of alternating exposure/recovery periods. Three predominant gene expression responses were observed: adaptive (return to baseline), sustained (maintained expression during treatment), and chronic (maintained expression posttreatment). Overall, 25 genes exhibited statistically significant changes: 14 genes exclusively elevated, 10 genes exclusively depressed, and 1, interleukin-8 (IL8), exhibiting both up- and downregulation in the seven groups. The most responsive genes were osteopontin (34-fold upregulation) and CXCL14 (23-fold downregulation). Our observations suggest that specific genes involved in inflammatory pathways respond to CSC in chronic, sustained, or adaptive patterns with the chronic pattern as the predominant behavior.

Osteopontin expression in normal and hypobaric hypoxia-exposed rats

AIM

Experimental pulmonary hypertension induced in a hypobaric hypoxic environment (HHE) is characterized by structural remodelling of the heart and pulmonary arteries. Osteopontin (OPN) has emerged as a key factor in cardiovascular remodelling in response to pressure or volume overload. We studied the possible effects of HHE on the OPN synthesis system.

METHODS

One hundred and forty-eight male Wistar rats were housed in a chamber with conditions equivalent of an altitude of 5500 m for up to 21 days.

RESULTS

Plasma OPN protein level was found to be significantly decreased on day 0.5 of exposure to HHE, as was the level in the adrenal gland (which secreted highest levels of OPN protein). In the right ventricle of the heart (mRNA) and the lung (protein), OPN expression was found to be significantly increased only on day 1 and day 5, respectively, of exposure to HHE. By immunohistochemistry, the distribution and intensity of OPN protein in several organs were found to alter during exposure to HHE. However, these changes in OPN synthesis did not coincide with the moderate increase in pulmonary arterial pressure (PAP) (maximal mean PAP, 24.5 mmHg) during HHE.

CONCLUSION

Pulmonary hypertension in HHE with conditions equivalent of an altitude of 5500 m may induce little or no OPN in heart and lung. Sustained induction may require a more severe PAP overload.

Enhanced osteopontin expression in a murine model of allergen-induced airway remodelling

BACKGROUND

Airway remodelling is a central pathophysiological feature of chronic asthma. A wide variety of cytokines and growth factors are likely to be involved in the development of airway remodelling. Osteopontin (OPN) is a cytokine with pro-fibrotic properties; however, its role in airway remodelling in asthma has not been explored.

OBJECTIVE

To determine the expression and cellular sources of OPN in a murine model of chronic allergen-induced airway remodelling.

METHODS

BALB/c mice were sensitized and exposed to ovalbumin (OVA) or saline inhalations for 5 weeks and killed 24 h after the last inhalation. The following parameters of inflammation and remodelling were assessed: differential cell counts in bronchoalveolar lavage (BAL) fluid lung collagen content (colorimetric biochemical assay) and peribronchial smooth muscle content (immunohistochemistry, followed by image analysis). OPN expression in BAL and lung tissue was determined by PCR and ELISA. The cellular source and distribution of OPN were evaluated by immunohistochemistry and immunofluorescence.

RESULTS

OPN expression is up-regulated in lung tissue and in BAL fluid of OVA-treated mice and correlates with collagen content and peribronchial smooth muscle area. In addition, OPN significantly increases collagen deposition in vitro in a murine lung cell line. Cells producing OPN include the airway epithelium and cells of the submucosal inflammatory infiltrate (T cells, eosinophils, and macrophages). Positive staining for OPN was also observed in bronchial tissue from human asthmatic subjects.

CONCLUSION

OPN expression in the lungs is increased in a murine model of allergen-induced chronic airway remodelling, suggesting a role for this cytokine in airway remodelling in asthma.

Osteopontin regulates hindlimb-unloading-induced lymphoid organ atrophy and weight loss by modulating corticosteroid production

Osteopontin (OPN), a multifunctional secreted phosphoglycoprotein, plays diverse roles in bone biology, immune regulation, cell survival, inflammation, and cancer metastasis. Here we show its role in determining lymphocyte homeostasis and body mass in response to hindlimb unloading (HU), a model for evaluating effects of weightlessness on the musculoskeletal and other physiological systems. Using this stress model, we compared OPN(-/-) mice with OPN(+/+) mice subjected to HU for 3 days. Whereas OPN(+/+) mice suffered a marked reduction of body weight and significant spleen and thymus atrophy, OPN(-/-) mice exhibited minor weight loss and much less spleen and thymus atrophy. The HU-induced lymphoid organ atrophy was the result of dramatically diminished numbers, respectively, of T and B cells in the spleen and CD4(+)CD8(+) double-positive cells in the thymus of OPN(+/+) mice. Increased levels of corticosterone, which modulates lymphocyte activation responses and apoptosis during stress, were found only in OPN(+/+) mice. Apoptotic cell death was evident in the spleen and thymus of OPN(+/+) mice subjected to HU but not in OPN(-/-)mice. Importantly, lymphocytes from both OPN(+/+) and OPN(-/-) mice were equally sensitive to corticosteroid-induced apoptosis. These results reveal that OPN is required for enhanced corticosterone production, immune organ atrophy, and weight loss in mice subjected to HU.

Utility of osteopontin and serum mesothelin in malignant pleural mesothelioma diagnosis and prognosis assessment

PURPOSE

Malignant mesothelioma is a highly aggressive tumor and is often diagnosed too late for a curative treatment. We compared diagnostic and prognostic values of mesothelin and osteopontin in 172 patients suspected of malignant pleural mesothelioma (MPM) and in a control group of 112 asymptomatic asbestos-exposed subjects.

EXPERIMENTAL DESIGN

Osteopontin and mesothelin were assayed with commercial ELISA kits in a series of 43 patients with pleural metastases of various carcinomas, 33 patients with benign pleural lesions associated with asbestos exposure, 96 patients with MPMs, and 112 asbestos-exposed healthy subjects. Results were correlated with patient's diagnosis and survival.

RESULTS

Serum osteopontin level was higher in MPM patients compared with healthy asbestos-exposed subjects and had a good capability to distinguish between these two populations. However, osteopontin was unable to distinguish between MPM and pleural metastatic carcinoma or benign pleural lesions associated with asbestos exposure. Neither plasma nor pleural fluid osteopontin were more powerful in this respect. Serum mesothelin had a good ability for diagnosing MPM but was unable to identify patients with nonepithelioid mesothelioma subtypes. Survival analysis identified tumor histologic subtype along with serum osteopontin and serum mesothelin as independent prognostic factors in mesothelioma patients.

CONCLUSIONS

Osteopontin has a lower diagnostic accuracy than mesothelin in patients suspected of MPM. Insufficient specificity limits osteopontin utility as diagnostic marker. Both molecules have a potential value as prognostic markers.