Interleukin-10 and Th2 cytokines differentially regulate osteopontin expression in human monocytes and dendritic cells

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

The interaction between cancer associated fibroblasts and tumor associated macrophages via the osteopontin pathway in the tumor microenvironment of hepatocellular carcinoma

BACKGROUND

Cancer-tumor associated macrophage (TAM)-cancer associated fibroblast (CAF) interactions are an important factor in the tumor microenvironment of hepatocellular carcinoma.

MATERIALS AND METHODS

Hepatic stellate cells (HSCs) were cultured with cancer cell-conditioned medium (Ca.-CM), TAM-CM and CAF-CM, and the expression of CAF markers were evaluated by RT-PCR. Whether HSCs cultured with Ca.-CM, TAM-CM and CAF-CM contributed to the enhanced malignancy of cancer cells was examined using proliferation, invasion and migration assays. Furthermore, the differences between these three types of CM were evaluated using cytokine arrays.

RESULTS

HSCs cultured with Ca.-CM, TAM-CM and CAF-CM showed significantly increased mRNA expression of αSMA, FAP and IL-6. All HSCs cultured with each CM exhibited significantly increased proliferation, invasion and migration of cancer cells. The osteopontin concentration was significantly higher in HSCs cultured with TAM-CM than the other CAF-CMs. Osteopontin inhibition significantly reduced osteopontin secretion from HSCs cultured with TAM-CM and suppressed the proliferation and invasion of cancer cells enhanced by HSCs cultured with TAM-CM.

CONCLUSIONS

We observed enhanced osteopontin secretion from TAMs, and this increased osteopontin further promoted osteopontin secretion from HSCs cultured with TAM-CM, leading to increased malignancy. For the first time, we demonstrated the importance of cancer-TAM-CAF interactions via osteopontin in hepatocellular carcinoma.

Angiogenesis in Lymph Nodes Is a Critical Regulator of Immune Response and Lymphoma Growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies.

Role of osteopontin in dendritic cell shaping of immune responses

Osteopontin (OPN) is a pleiotropic cytokine produced both by immune and non-immune cells and active on different cellular targets. OPN production has been associated with several pathological conditions, including autoimmune diseases (e.g. lupus, multiple sclerosis and rheumatoid arthritis) and cancer. Emerging evidence suggests that the role of OPN has been underestimated, as it seems to be working at multiple levels of immune regulation, such as the shaping of T cell effector responses, the regulation of the tumor microenvironment, and the functional interaction with mesenchymal stromal cells. In this context, dendritic cells (DCs) play a crucial role being both an important source and a cellular target for OPN action. DC family is composed by several cell subsets endowed with specific immune functions. OPN exerts its biological functions through multiple receptors and is produced in different intracellular and secreted forms. OPN production by DC subsets is emerging as a crucial mechanism of regulation in normal and pathological conditions and starts to be exploited as a therapeutic target. This review will focus on the role of DC-derived OPN in shaping immune response and on the complex role of this cytokines in the regulation in immune response.

Leptin/Osteopontin Axis Regulated Type 2T Helper Cell Response in Allergic Rhinitis with Obesity

The prevalence of allergic rhinitis (AR) and obesity in children increased concurrently during recent decades. However, the molecular pathway involved in the interaction between obesity and AR is still unclear. We aimed to investigate the interaction between leptin and osteopontin (OPN) and their effect on T helper (T_H) response in the development of AR in children. Thirty AR and 30 healthy children with or without obesity were enrolled. Serum leptin and OPN levels were measured and their relationship with T_H1/2 cytokines was analyzed. T_H cell differentiation and cytokine production in peripheral blood mononuclear cells (PBMCs) stimulated by leptin and/or OPN were analyzed by enzyme linked immunosorbent assay (ELISA). Obese AR mice models were established to verify the effect of obesity on leptin and OPN as well T_H regulation. Immunoprecipitation was performed to confirm the interaction between OPN and leptin in CD4+ T cells. Our results showed elevated serum leptin and OPN in AR children correlated with T_H2 cytokines expression. Leptin and OPN enhanced T_H2 inflammation in house dust mite stimulated PBMCs from AR children synergistically. Obese AR mice showed as more severe inflammatory reaction, symptoms and expression of nasal leptin and OPN compared with other groups. Immunoprecipitation suggested that OPN and leptin may interact with each other and this process may be mediated by α4 integrin and PI3K/AKT pathway in CD4+ T cells. Our data provide evidence that leptin-mediated OPN upregulation promote T_H2 inflammation in AR and this process is achieved through the α4 integrin and PI3K/AKT signaling pathways.

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Previous studies suggested that both leptin and osteopontin are increased in allergic rhinitis patients and related to the severity of disease. We also provide evidence that leptin and osteopontin contributes to T_H2-skewed airway diseases. In the present study, our data suggested that obesity and allergic rhinitis interacted closely through leptin and OPN, and these cytokines may be used as potential biomarkers for disease severity of allergic rhinitis despite that more studies were needed.

Interleukin-18 Amplifies Macrophage Polarization and Morphological Alteration, Leading to Excessive Angiogenesis

M2 macrophage (Mφ) promotes pathologic angiogenesis through a release of pro-angiogenic mediators or the direct cell–cell interaction with endothelium in the micromilieu of several chronic inflammatory diseases, including rheumatoid arthritis and cancer, where interleukin (IL)-18 also contributes to excessive angiogenesis. However, the detailed mechanism remains unclear. The aim of this study is to investigate the mechanism by which M2 Mφs in the micromilieu containing IL-18 induce excessive angiogenesis in the in vitro experimental model using mouse Mφ-like cell line, RAW264.7 cells, and mouse endothelial cell line, b.End5 cells. We discovered that IL-18 acts synergistically with IL-10 to amplify the production of Mφ-derived mediators like osteopontin (OPN) and thrombin, yielding thrombin-cleaved form of OPN generation, which acts through integrins α4/α9, thereby augmenting M2 polarization of Mφ with characteristics of increasing surface CD163 expression in association with morphological alteration. Furthermore, the results of visualizing temporal behavior and morphological alteration of Mφs during angiogenesis demonstrated that M2-like Mφs induced excessive angiogenesis through the direct cell–cell interaction with endothelial cells, possibly mediated by CD163.

Potent pro-inflammatory and pro-fibrotic molecules, osteopontin and galectin-3, are not major disease modulators of laminin α2 chain-deficient muscular dystrophy

A large number of human diseases are caused by chronic tissue injury with fibrosis potentially leading to organ failure. There is a need for more effective anti-fibrotic therapies. Congenital muscular dystrophy type 1A (MDC1A) is a devastating form of muscular dystrophy caused by laminin α2 chain-deficiency. It is characterized with early inflammation and build-up of fibrotic lesions, both in patients and MDC1A mouse models (e.g. dy^3K/dy^3K). Despite the enormous impact of inflammation on tissue remodelling in disease, the inflammatory response in MDC1A has been poorly described. Consequently, a comprehensive understanding of secondary mechanisms (impaired regeneration, enhanced fibrosis) leading to deterioration of muscle phenotype in MDC1A is missing. We have monitored inflammatory processes in dy^3K/dy^3K muscle and created mice deficient in laminin α2 chain and osteopontin or galectin-3, two pro-inflammatory and pro-fibrotic molecules drastically increased in dystrophic muscle. Surprisingly, deletion of osteopontin worsened the phenotype of dy^3K/dy^3K mice and loss of galectin-3 did not reduce muscle pathology. Our results indicate that osteopontin could even be a beneficial immunomodulator in MDC1A. This knowledge is essential for the design of future therapeutic interventions for muscular dystrophies that aim at targeting inflammation, especially that osteopontin inhibition has been suggested for Duchenne muscular dystrophy therapy.

Osteopontin That Is Elevated in the Airways during COPD Impairs the Antibacterial Activity of Common Innate Antibiotics

Bacterial infections of the respiratory tract contribute to exacerbations and disease progression in chronic obstructive pulmonary disease (COPD). There is also an increased risk of invasive pneumococcal disease in COPD. The underlying mechanisms are not fully understood but include impaired mucociliary clearance and structural remodeling of the airways. In addition, antimicrobial proteins that are constitutively expressed or induced during inflammatory conditions are an important part of the airway innate host defense. In the present study, we show that osteopontin (OPN), a multifunctional glycoprotein that is highly upregulated in the airways of COPD patients co-localizes with several antimicrobial proteins expressed in the airways. In vitro, OPN bound lactoferrin, secretory leukocyte peptidase inhibitor (SLPI), midkine, human beta defensin-3 (hBD-3), and thymic stromal lymphopoietin (TSLP) but showed low or no affinity for lysozyme and LL-37. Binding of OPN impaired the antibacterial activity against the important bacterial pathogens Streptococcus pneumoniae and Pseudomonas aeruginosa. Interestingly, OPN reduced lysozyme-induced killing of S. pneumoniae, a finding that could be explained by binding of OPN to the bacterial surface, thereby shielding the bacteria. A fragment of OPN generated by elastase of P. aeruginosa retained some inhibitory effect. Some antimicrobial proteins have additional functions. However, the muramidase-activity of lysozyme and the protease inhibitory function of SLPI were not affected by OPN. Taken together, OPN can contribute to the impairment of innate host defense by interfering with the function of antimicrobial proteins, thus increasing the vulnerability to acquire infections during COPD.

The immunological effect of hyaluronan in tumor angiogenesis

The relationship between the immune system and angiogenesis has been described in several contexts, both in physiological and pathological conditions, as pregnancy and cancer. In fact, different types of immune cells, such as myeloid, macrophages and denditric cells, are able to modulate tumor neovascularization. On the other hand, tumor microenvironment also includes extracellular matrix components like hyaluronan, which has a deregulated synthesis in different tumors. Hyaluronan is a glycosaminoglycan, normally present in the extracellular matrix of tissues in continuous remodeling (embryogenesis or wound healing processes) and acts as an important modulator of cell behavior by different mechanisms, including angiogenesis. In this review, we discuss hyaluronan as a modulator of tumor angiogenesis, focusing in intracellular signaling mediated by its receptors expressed on different immune cells. Recent observations suggest that the immune system is an important component in tumoural angiogenesis. Therefore, immune modulation could have an impact in anti-angiogenic therapy as a new therapeutic strategy, which in turn might improve effectiveness of treatment in cancer patients.

Expression and regulation of osteopontin in chronic rhinosinusitis with nasal polyps

BACKGROUND

Osteopontin (OPN) has been proposed to be associated with airway inflammation including asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). This study sought to evaluate the expression and regulation of the OPN in CRSwNP patients.

METHODS

Nasal polyp (NP) tissues and normal tissues were collected from 30 CRSwNP patients and 16 control subjects. The expression and regulation of OPN, as well eosinophil (EOS) accumulation and activation, were examined in nasal tissues using DNA microarray, immunohistochemical (IHC), immunofluorescent (IF) staining and qPCR analysis. Moreover, the regulation of OPN in nasal epithelial cells and its effects on migration and activation of EOS were evaluated in vitro using flow cytometry, ELISA, qPCR and Western blot, etc.

RESULTS

DNA microarray analysis identified OPN as one of the 19 upregulated genes in polyp tissues. The mean number of OPN(+) cells in polyp tissues was found to be significantly increased compared with the normal controls (P < 0.01), and OPN(+) cells in polyp tissues significantly correlated with tissue eosinophilia [major basic protein (MBP)(+) cells; r = 0.51, P < 0.01]. Accordingly, the mRNA and protein levels of OPN in NP tissues were significantly higher than those in normal controls (P < 0.01). Poly I:C, flagellin and TLR-9 agonist CpG ODN, as well as TNF-α, IFN-γ, IL-6, IL-17A and TGF-β, significantly increased OPN mRNA expression in cultured PECs and NECs (P < 0.05). Recombinant human OPN significantly promoted the migration of EOS, as well as enhanced EOS cationic protein (ECP) production, in an in vitro dispersed NP cells (DNPCs) culture system (P < 0.05).

CONCLUSIONS

OPN promotes eosinophilic nasal inflammation in CRSwNP patients, which may represent a promising therapeutic target.

Osteopontin: a potential biomarker of Gaucher disease

Gaucher disease (GD) is one of the most prevalent lysosomal storage disorders and the disorder that has the greatest immune system involvement. Pathologic lipid accumulation in macrophages accounts for a small amount of the additional tissue mass in the liver and spleen. The additional increase may be related to an inflammatory response because Gaucher cells secrete inflammatory mediators. Osteopontin (OPN) is a protein identified in cancer cells and in bone cells that is produced by several types of immune cells including T-cells and macrophages. We report here elevated OPN levels in the plasma of type 1 GD patients and its sensitive response to enzyme replacement therapy. The mean OPN value of GD patients receiving ERT was similar to the values of controls and patients with other lysosomal disorders. When comparing untreated and treated GD patients, the p value was <0.001. In GD, OPN appears to be more sensitive to ERT than chitotriosidase and can be used during the follow-up of patients who are chitotriosidase deficient. Additional extended studies are required to relate variations in the OPN levels to clinical findings and response to therapy in GD patients.

Elevated level of serum osteopontin in school-age children with asthma

BACKGROUND

The role of osteopontin (OPN) has not been elucidated in childhood asthma.

OBJECTIVE

Our purpose was to investigate whether OPN levels change due to allergic inflammation in pre-school and school-age children.

METHODS

In this prospective, cross-sectional study, 42 healthy children and a total of 51 children with asthma were recruited. OPN levels and its association with clinical and laboratory parameters were investigated in the study population. The asthma group were divided into two groups with respect to age, ≤ 5-years (n = 23) and >5-years (n = 28), and labelled Asthma Group 1 and Asthma Group 2, respectively. OPN levels were compared between subgroups.

RESULTS

Serum OPN levels were significantly higher in the asthma group when compared to the control group (p = 0.004). OPN levels were similar in Asthma Group 1 and control groups, whereas it was found to be higher in Asthma Group 2 (p>0.025, p = 0.001, respectively). In the >5-years age asthmatic group, OPN levels of the patients with allergic rhinitis (n = 15) were higher than those of the patients (n=13) without allergic rhinitis (p = 0.021).

CONCLUSION

The study underscores the relationship between childhood asthma and OPN as the first study in the literature. In this study we found that OPN, which plays a role in Th2 mediated inflammation, may also play a role in childhood asthma. The fact that OPN levels do not increase in preschool-age children with asthma might be due to the transient wheezing in this group.

The impact of the immune system on tumor: angiogenesis and vascular remodeling

Angiogenesis, the formation of new blood vessels, as well as inflammation with massive infiltration of leukocytes are hallmarks of various tumor entities. Various epidemiological, clinical, and experimental studies have not only demonstrated a link between chronic inflammation and cancer onset but also shown that immune cells from the bone marrow such as tumor-infiltrating macrophages significantly influence tumor progression. Tumor angiogenesis is critical for tumor development as tumors have to establish a blood supply in order to progress. Although tumor cells were first believed to fuel tumor angiogenesis, numerous studies have shown that the tumor microenvironment and infiltrating immune cell subsets are important for regulating the process of tumor angiogenesis. These infiltrates involve the adaptive immune system including several types of lymphocytes as well as cells of the innate immunity such as macrophages, neutrophils, eosinophils, mast cells, dendritic cells, and natural killer cells. Besides their known immune function, these cells are now recognized for their crucial role in regulating the formation and the remodeling of blood vessels in the tumor. In this review, we will discuss for each cell type the mechanisms that regulate the vascular phenotype and its impact on tumor growth and metastasis.

Role of osteopontin, a multifunctional protein, in allergy and asthma

Osteopontin (OPN) is an extracellular matrix protein and immune modulator with a wide range of functions. OPN is recognized as a key cytokine in Th1 immune responses, yet its potential involvement in allergic/asthmatic responses has been investigated only recently. Current data from molecular and cellular studies and studies of OPN-deficient mice provide evidence that OPN plays multiple roles in the regulation of allergic responses, including regulation of IgE response, inflammatory cell migration, and the development of airway fibrosis and angiogenesis. These results suggest that OPN is a pleiotropic cytokine that functions both systemically and locally in tissue mucosa. Notably, OPN is able to exert its effects through different functional domains, and the secreted and intracellular forms of OPN may have distinct functions. Future research to elucidate all aspects of OPN function is needed to ultimately establish its role in the regulation of immune responses and various disease processes, including those critically involved in the development of allergies and asthma.

Osteopontin in macrophage function

The secreted phosphorylated protein osteopontin (OPN) is expressed in a variety of tissues and bodily fluids, and is associated with pathologies including tissue injury, infection, autoimmune disease and cancer. Macrophages are ubiquitous, heterogeneous cells that mediate aspects of cell and tissue damage in all these pathologies. Here, the role of OPN in macrophage function is reviewed. OPN is expressed in macrophage cells in multiple pathologies, and the regulation of its expression in these cells has been described in vitro. The protein has been implicated in multiple functions of macrophages, including cytokine expression, expression of inducible nitric oxide synthase, phagocytosis and migration. Indeed, the role of OPN in cells of the macrophage lineage might underlie its physiological role in many pathologies. However, there are numerous instances where the published literature is inconsistent, especially in terms of OPN function in vitro. Although the heterogeneity of OPN and its receptors, or of macrophages themselves, might underlie some of these inconsistencies, it is important to understand the role of OPN in macrophage biology in order to exploit its function therapeutically.

The expression of osteopontin and its association with Clara cell 10 kDa protein in allergic rhinitis

BACKGROUND

Osteopontin (OPN) is a multifunctional protein that has recently been linked to allergic diseases. Clara cell 10 kDa protein (CC10) is another protein linked to allergy, and has been suggested to have an inhibitory role in inflammatory airway diseases. At this time, it is not known whether OPN is involved in allergic rhinitis (AR) or if there is any association between CC10 and OPN in AR.

OBJECTIVE

To study the expression of OPN and its potential association with CC10 in AR.

METHODS

The expression of CC10 and OPN in nasal mucosa of AR patients was investigated. AR animal models were established by using wild-type and CC10-knockout mice. In some experiments, human recombinant CC10 protein was given to AR mice during either sensitization or challenge. The phenotypic changes were examined by histology and real-time RT-PCR. The direct effect of CC10 on the OPN expression in spleen mononuclear cells and on the OPN-induced inflammatory cytokine expression in BEAS-2B cells was measured through in vitro cell culture.

RESULTS

OPN expression was up-regulated, with a concomitant down-regulation of CC10, in AR patients, showing a significant negative correlation between their expression. Compared with control mice sensitized with PBS, the OPN expression was significantly increased in AR mice; such an increase was more prominent in CC10-knockout mice, compared with wild-type. Administration of CC10 during both sensitization and challenge could markedly ameliorate Th2-skewed inflammation and OPN expression in nasal mucosa. CC10 administration at the sensitization phase could also reduce spleen OPN expression. The in vitro study showed that CC10 directly down-regulated the OPN expression in spleen mononuclear cells stimulated with OVA and suppressed the OPN-induced expression of Th2 cytokines and pro-inflammatory cytokines in BEAS-2B cells.

CONCLUSION

In the context of allergic airway responses, CC10 can inhibit OPN expression and suppress the Th2-promoting function of OPN, resulting in CC10's inhibitory biological effects.

Osteopontin levels are elevated in patients with eosinophilic pneumonia

BACKGROUND AND OBJECTIVE

Osteopontin is a key cytokine involved in pro-inflammatory T helper type 1 (Th1)-associated immune responses, which has recently been implicated in allergic diseases. We investigated the pathogenic role of osteopontin in eosinophilic pneumonia.

METHODS

The concentrations of osteopontin and Th1- or Th2-associated cytokines were measured in BAL fluid (BALF) from 41 patients with eosinophilic pneumonia, including those with acute (AEP, n = 12), chronic (CEP, n = 16), or drug-induced eosinophilic pneumonia (DEP, n = 13). The results were compared with those from patients with other interstitial lung diseases. Immunocytochemistry and double immunofluorescence labelling were performed to determine the cellular source of osteopontin.

RESULTS

Osteopontin was significantly elevated in BALF from patients with eosinophilic pneumonia as compared with BALF from patients with drug-induced interstitial pneumonia, hypersensitivity pneumonitis, idiopathic interstitial pneumonia, or sarcoidosis, and also compared with BALF from healthy volunteers. Osteopontin concentrations elevated at the time of exacerbation decreased during clinical improvement, either spontaneously or as a result of corticosteroid therapy. Elevated concentrations of CXCL10, CCL17 and IL-10 were also detected in BALF from patients with eosinophilic pneumonia. Osteopontin concentrations in BALF of AEP patients were correlated with IL-5, as well as IL-10, CCL11, CCL17 and CXCL10 concentrations. In AEP and DEP patients, serum osteopontin concentrations were also elevated. Double immunofluorescence labelling showed that in patients with eosinophilic pneumonia, osteopontin was expressed in lung eosinophils.

CONCLUSIONS

Osteopontin is likely to contribute to the development of inflammation in patients with eosinophilic pneumonia.

Plasma osteopontin concentration correlates with the severity of hepatic fibrosis and inflammation in HCV-infected subjects

BACKGROUND

The association between OPN level and the histological severity of hepatic fibrosis and inflammation in hepatitis C virus (HCV) induced liver fibrosis remains unknown.

METHODS

120 chronic HCV-infected subjects and 75 controls were enrolled in this study. Assessment of liver histology was performed based on liver biopsy. Plasma OPN levels were determined.

RESULTS

Significant differences were noted in the mean plasma OPN levels between subjects with extensive fibrosis and those with mild fibrosis (4.29+/-1.01 ng/ml vs. 2.15+/-0.63 ng/ml, respectively; p<0.001). Similarly, the subjects with higher histological activity index (HAI) score had elevated OPN levels than those with mild HAI score (4.41+/-1.11 ng/ml vs. 2.25+/-0.94 ng/ml, respectively; p<0.001). The correlation between the plasma OPN levels and the severity of liver fibrosis degree and HAI score were noted (r=0.945, and r=0.788, respectively both p<0.001). Logistic regression analysis showed that serum OPN was an independent risk factor contributing to extensive liver fibrosis and inflammation (p=0.0018 and p<0.001, respectively) in patients with HCV subjects.

CONCLUSION

The plasma OPN level is correlated with the severity of liver fibrosis and inflammation, suggesting OPN could be used as a biomarker to evaluate the severity of liver damages in HCV subjects.

Regulatory role of DC-derived osteopontin in systemic allergen sensitization

Osteopontin (OPN) is a secreted phosphoglycoprotein with a wide range of functions, and is involved in various pathophysiological conditions. However, the role of OPN in IgE and Th2-associated allergic responses remains incompletely defined. The aim of this study was to elucidate the role of OPN in systemic allergen sensitization in mice. When compared with OPN(+/+) mice, significantly increased levels of OVA-induced IgE were found in OPN(-/-) mice. OPN(-/-) DC demonstrated an increased capacity to enhance Th2 cytokine production in CD4+ T cells from sensitized OPN(+/+) mice. Furthermore, significantly reduced levels of IL-12p70 expression were seen in LPS-stimulated OPN(-/-) DC as compared with the WT DC, and the reduction was reversible by the addition of recombinant OPN (rOPN). rOPN was able to suppress OVA-induced IL-13 production in the cultures of CD4 and OPN(-/-) DC, but this inhibitory activity was neutralized by the addition of anti-IL-12 Ab. In addition, administration of rOPN in vivo suppressed OVA-specific IgE production; however, this suppressive effect was abrogated in IL-12-deficient mice. These results indicate that DC-derived OPN plays a regulatory role in the development of systemic allergen sensitization, which is mediated, at least in part, through the production of endogenous IL-12.

Osteopontin: an early innate immune marker of Escherichia coli mastitis harbors genetic polymorphisms with possible links with resistance to mastitis

Background

Mastitis is the most important disease in dairy cows and it causes significant lost of profit to producers. Identification of the genes, and their variants, involved in innate immune responses is essential for the understanding of this inflammatory disease and to identify potential genetic markers for resistance to mastitis. The progeny of dairy cows would benefit from receiving favourable alleles that support greater resistance to infection, thus reducing antibiotic use. This study aims to identify a key gene in the innate immune response to mastitis, led us to evaluate its genetic association with somatic cell score (SCS), which is an indicator of clinical mastitis, and to evaluate its impact on other traits related to milk production.

Results

The osteopontin transcript (SPP1) was identified in the somatic cells from cows experimentally infected with Escherichia coli. By selecting bulls with extreme estimated breeding values (EBVs) for SCS, which is an indicator of mammary gland health, four DNA polymorphisms in the SPP1 genomic sequence were found. Statistical analysis revealed that the SNP SPP1c.-1301G>A has an impact on EBV for SCS (P < 0.001) Using an allele substitution model, SPP1c.-1251C>T, SPP1c.-430G>A, and SPP1c.*40A>C have an impact on SCS whereas SPP1c.-1301G>A has an effect on the EBVs for milk yield (second and third lactations), fat and protein percentages (all three lactations). Analysis revealed statistically significant differences between haplotype groups at a comparison-wise level with sire EBVS for SCS for the first (P = 0.012), second (P < 0.001), and third (P < 0.001) lactations.

Conclusion

This study reports the link between DNA polymorphisms of SPP1, the number of milk immune cells and, potentially, the susceptibility to mastitis. These SNPs were identified by in silico search to be located in transcription factor recognition sites which factors are presumably involved in the Th1 immune response and in the Th2 regulation pathway. Indeed, one SNP abolished the SP1 recognition site, whereas another SNP affected the transcription binding factor IKAROS. All together, these findings support the genetic potential of these variants in terms of selection for the improvement of mastitis resistance in dairy cows.

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.

Production of Th1- and Th2-dependent cytokines induced by the Chinese medicine herb, Rhodiola algida, on human peripheral blood monocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Rhodiola algida, an herb ingredient used in Chinese medicine, has been clinically proven to be effective in enhancing human immune responses.

AIM OF STUDY

This study attempted to identify the potential immunomodulatory effect of Rhodiola algida extract in human immune system in vitro, and to examine its underlying molecular effects.

MATERIALS AND METHODS

Firstly, the bioactive marker compound salidroside was used for standardization of Rhodiola algida extract by reversed-phase HPLC. Secondly, the regulation of human immune responses was investigated in human peripheral blood monocytes. A series of cytokines known to play important roles in the human immune responses were examined.

RESULTS

The current study provided quantitative assay for the marker compound, salidroside, in the Rhodiola algida extract for ensuring the quality consistency of Rhodiola algida used in the following experiments. Biological assay indicated that Rhodiola algida stimulates human peripheral blood lymphocytes and its underlying immunomodulatory effects probably through its regulation of IL-2 in Th1 cells and IL-4, IL-6, IL-10 in Th2 cells.

CONCLUSION

The findings may enable us to further explain the pharmacological properties in Chinese medicine and make Rhodiola algida a very promising immunomodulating agent.

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 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.

Expression of osteopontin in chronic rhinosinusitis with and without nasal polyps

BACKGROUND

Osteopontin (OPN) is a multifunctional 34-kDa extracellular matrix protein that can influence the inflammatory process. However, the presence of OPN in human sinonasal mucosa and its roles in the inflammatory process of chronic rhinosinusitis (CRS) are not clear. This study investigated the expression of OPN in human sinonasal mucosa, its cytokine-driven expression regulation, and its effect on cytokine production in sinonasal mucosa.

METHODS

Surgical samples were investigated by means of quantitative reverse transcriptase polymerase chain reaction for evaluation of OPN messenger RNA (mRNA) expression, and the presence and location of OPN protein expression were analyzed using immunohistochemistry. Furthermore, nasal explant culture was used to investigate the mutual regulatory interactions between interferon (IFN)-gamma, interleukin (IL)-4, IL-5, IL-13, IL-1beta, and tumor necrosis factor (TNF)-alpha and OPN in sinonasal mucosa.

RESULTS

Osteopontin expression was significantly upregulated in CRS tissues compared with control tissues. There was a further significant increase of OPN expression in patients with nasal polyps (NPs) and asthma. Immunohistochemistry revealed positive staining of OPN in epithelial cells, submucosal glands, infiltrating cells, and extracellular matrix. Osteopontin mRNA was induced by IFN-gamma, IL-1beta, and TNF-alpha, but inhibited by IL-4 and IL-13. On the contrary, OPN induced IFN-gamma, IL-4, IL-5, IL-13, IL-1beta, and TNF-alpha production in sinonasal mucosa.

CONCLUSIONS

The expression of OPN is upregulated in CRS. The mutual regulatory interactions between OPN and inflammatory cytokines suggest that OPN may play an important role in the pathogenesis of CRS.

The role of myeloid cells in the promotion of tumour angiogenesis

The use of various transgenic mouse models and analysis of human tumour biopsies has shown that bone marrow-derived myeloid cells, such as macrophages, neutrophils, eosinophils, mast cells and dendritic cells, have an important role in regulating the formation and maintenance of blood vessels in tumours. In this Review the evidence for each of these cell types driving tumour angiogenesis is outlined, along with the mechanisms regulating their recruitment and activation by the tumour microenvironment. We also discuss the therapeutic implications of recent findings that specific myeloid cell populations modulate the responses of tumours to agents such as chemotherapy and some anti-angiogenic therapies.

Dendritic cell–endothelial cell cross-talk in angiogenesis

Dendritic cells (DCs) are professional antigen-presenting cells that have a pivotal role in the onset and regulation of adaptive immune responses. DCs have the ability to regulate inflammation through their capacity to release cytokines and chemokines and kill pathogens, which they share with other phagocytes. Recent observations have shown that different DC subsets produce and release various pro- and anti-angiogenic mediators depending on their activation status and cytokine milieu. In particular, alternatively activated DCs exert a potent pro-angiogenic activity that is mediated by the prototypic angiogenic growth factor vascular endothelial growth factor-A (VEGF-A). In turn, pro- and anti-angiogenic mediators can affect the biology of DCs, modulating their differentiation and maturation. Finally, DCs can trans-differentiate into endothelial-like cells, possibly contributing to vasculogenesis in the adult. Thus, DCs might exert an important impact on the neovascularization process in different physiopathological conditions.

Hepatoprotective role of endogenous interleukin-13 in a murine model of acetaminophen-induced liver disease

Recent evidence suggests that a deficiency in one or more hepatoprotective regulatory mechanisms may contribute to determining susceptibility in drug-induced liver disease. In the present study, we investigated the role of interleukin (IL)-13 in acetaminophen (APAP)-induced liver disease (AILD). Following APAP (200 mg/kg) administration to male C57BL/6 wild-type (WT) mice, hepatotoxicity developed up to 24 h post-APAP, with a concomitant increase in serum IL-13 concentration. Pretreatment of these mice with an IL-13-neutralizing antibody exacerbated liver injury, as did APAP administration to IL-13 knockout (KO) mice in comparison to WT mice. No difference was observed in either overall APAP-protein adduct formation or liver glutathione levels between KO and WT mice following APAP administration, suggesting that the increased susceptibility of IL-13 KO mice to AILD was not due to enhanced APAP bioactivation but rather injurious downstream events. In this regard, multiplex antibody arrays were used to identify potential IL-13-regulated biomarkers, including various cytokines and chemokines, as well as nitric oxide (NO), associated with AILD that were present at higher concentrations in the sera of APAP-treated IL-13 KO mice than in WT mice. Subsequent inhibition studies determined interferon-gamma, NO, neutrophils, natural killer cells, and natural killer cells with T-cell receptors had pathologic roles in AILD in IL-13 KO mice. Taken together, these results suggest that IL-13 is a critical hepatoprotective factor modulating the susceptibility to AILD and may provide hepatoprotection, in part, by down-regulating protoxicant factors and cells associated with the innate immune system.