Osteopontin functionally activates dendritic cells and induces their differentiation toward a Th1-polarizing phenotype

APTAMERS: USHERING IN NEW HOPES IN TARGETED GLIOBLASTOMA THERAPY

Glioblastoma, a formidable brain cancer, has remained a therapeutic challenge due to its aggressive nature and resistance to conventional treatments. Recent data indicate that aptamers, short synthetic DNA or RNA molecules can be used in anti-cancer therapy due to their better tumor penetration, specific binding affinity, longer retention in tumor sites and their ability to cross the blood-brain barrier. With the ability to modify these oligonucleotides through the selection process, and using rational design to modify them, post-SELEX aptamers offer several advantages in glioblastoma treatment, including precise targeting of cancer cells while sparing healthy tissue. This review discusses the pivotal role of aptamers in glioblastoma therapy and diagnosis, emphasizing their potential to enhance treatment efficacy and also highlights recent advancements in aptamer-based therapies which can transform the landscape of glioblastoma treatment, offering renewed hope to patients and clinicians alike.

Osteopontin/SPP1: a potential mediator between immune cells and vascular calcification

Vascular calcification (VC) is considered a common pathological process in various vascular diseases. Accumulating studies have confirmed that VC is involved in the inflammatory response in heart disease, and SPP1+ macrophages play an important role in this process. In VC, studies have focused on the physiological and pathological functions of macrophages, such as pro-inflammatory or anti-inflammatory cytokines and pro-fibrotic vesicles. Additionally, macrophages and activated lymphocytes highly express SPP1 in atherosclerotic plaques, which promote the formation of fatty streaks and plaque development, and SPP1 is also involved in the calcification process of atherosclerotic plaques that results in heart failure, but the crosstalk between SPP1-mediated immune cells and VC has not been adequately addressed. In this review, we summarize the regulatory effect of SPP1 on VC in T cells, macrophages, and dendritic cells in different organs' VC, which could be a potential therapeutic target for VC.

Involvement of Cyclooxygenase-2 in Establishing an Immunosuppressive Microenvironment in Tumorspheres Derived from TMZ-Resistant Glioblastoma Cell Lines and Primary Cultures

Glioblastoma (GBM) is characterized by an immunosuppressive tumor microenvironment (TME) strictly associated with therapy resistance. Cyclooxygenase-2 (COX-2) fuels GBM proliferation, stemness, and chemoresistance. We previously reported that COX-2 upregulation induced by temozolomide (TMZ) supported chemoresistance. Also, COX-2 transfer by extracellular vesicles released by T98G promoted M2 polarization in macrophages, whereas COX-2 inhibition counteracted these effects. Here, we investigated the COX-2 role in the stemness potential and modulation of the GBM immunosuppressive microenvironment. The presence of macrophages U937 within tumorspheres derived from GBM cell lines and primary cultures exposed to celecoxib (COX-2 inhibitor) with or without TMZ was studied by confocal microscopy. M2 polarization was analyzed by TGFβ-1 and CD206 levels. Osteopontin (OPN), a crucial player within the TME by driving the macrophages' infiltration, and CD44 expression was assessed by Western blot. TMZ strongly enhanced tumorsphere size and induced the M2 polarization of infiltrating macrophages. In macrophage-infiltrated tumorspheres, TMZ upregulated OPN and CD44 expression. These TMZ effects were counteracted by the concurrent addition of CXB. Remarkably, exogenous prostaglandin-E2 restored OPN and CD44, highlighting the COX-2 pivotal role in the protumor macrophages' state promotion. COX-2 inhibition interfered with TMZ's ability to induce M2-polarization and counteracted the development of an immunosuppressive TME.

A novel experimental model to investigate fungal involvement shows expression of Dectin-1 in periapical lesion pathogenesis

BACKGROUND

Candida albicans is linked to persistent endodontic lesions. However, the recognition receptor that identifies it is not explored previously.

OBJECTIVES

The aim of this study was to (1) establish a zymosan-induced model of apical periodontitis in mouse, (2) observe the expression of Dectin-1 and its possible relationship with toll-like receptor (TLR) 2 and (3) observe relationship between Osteopontin (OPN) and inflammatory cytokines.

METHODS

A total of 138 Naval Medical Research Institute (NMRI) mice were randomly divided into; Experimental Group n = 69 and Zymosan Group n = 69. Periapical periodontitis was developed in right maxillary molar. The animals were sacrificed at 7, 21 and 42 days. Bone blocks containing the mesial root (n = 15 for qRT-PCR, n = 45 for enzyme-linked immune sorbent assay (ELISA)) were collected for mRNA expression and ELISA. While whole maxilla (n = 3 from each time interval) were used for histology and immunohistochemical analysis. One way analysis of variance (ANOVA) and Tuckey's posthoc was used for statistical analysis at p ≤ .05.

RESULTS

TLR-2, Dectin-1 and TLR4-positive cells was detected at all time intervals in both groups. A strong positive correlation was observed between TLR-2 and Dectin-1 in both lesions (regular r = .680, p = .015, zymosan (r = .861, p < .001)). A significant correlation was found between OPN and tumour necrosis factor-alpha (TNF-α) in zymosan lesion (r = .827, p = .001).

CONCLUSIONS

Immune cells of inflamed periapical tissue expressed Dectin-1 receptor in response to the microbial challenge from infected root canals and showed positive correlation with TLR-2 and OPN suggesting a possible receptor collaboration mediated by OPN. The expression of OPN and TNF-α showed positive correlation in response to fungal antigen, indicating a possible relationship.

A Dual Role of Osteopontin in Modifying B Cell Responses

The occurrence of B cell aggregates within the central nervous system (CNS) has prompted the investigation of the potential sources of pathogenic B cell and T cell responses in a subgroup of secondary progressive multiple sclerosis (MS) patients. Nevertheless, the expression profile of molecules associated with these aggregates and their role in aggregate development and persistence is poorly described. Here, we focused on the expression pattern of osteopontin (OPN), which is a well-described cytokine, in MS brain tissue. Autopsied brain sections from MS cases with and without B cell pathology were screened for the presence of CD20⁺ B cell aggregates and co-expression of OPN. To demonstrate the effect of OPN on B cells, flow cytometry, ELISA and in vitro aggregation assays were conducted using the peripheral blood of healthy volunteers. Although OPN was expressed in MS brain tissue independent of B cell pathology, it was also highly expressed within B cell aggregates. In vitro studies demonstrated that OPN downregulated the co-stimulatory molecules CD80 and CD86 on B cells. OPN-treated B cells produced significantly lower amounts of IL-6. However, OPN-treated B cells also exhibited a higher tendency to form homotypic cell aggregates in vitro. Taken together, our data indicate a conflicting role of OPN in modulating B cell responses.

Osteopontin (OPN)/SPP1: from its biochemistry to biological functions in the innate immune system and the central nervous system (CNS)

Osteopontin (OPN) is a multifunctional protein, initially identified in osteosarcoma cells with its role of mediating osteoblast adhesion. Later studies revealed that OPN is associated with many inflammatory conditions caused by infections, allergic responses, autoimmunity and tissue damage. Many cell types in the peripheral immune system express OPN with various functions, which could be beneficial or detrimental. Also, more recent studies demonstrated that OPN is highly expressed in the central nervous system (CNS), particularly in microglia during CNS diseases and development. However, understanding of mechanisms underlying OPN's functions in the CNS is still limited. In this review, we focus on peripheral myeloid cells and CNS-resident cells to discuss the expression and functions of OPN.

Expression of Toll-like receptor 2, Dectin-1, and Osteopontin in murine model of pulpitis

OBJECTIVES

This in vivo animal study aimed to develop a murine model of pulpitis induced by pulp exposure with or without application of zymosan in Naval Medical Research Institute (NMRI) mice and observe expressions of Toll-like receptor (TLR)-2, TLR-4, Dectin-1, Osteopontin (OPN), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-1ß.

MATERIAL AND METHODS

A total of 168 NMRI mice were divided into two groups, i.e., group A (n = 84) (pulpitis induced by pulp exposure only) and group B (n = 84) (pulpitis induced by pulp exposure and zymosan application). Right maxillary molar pulps were exposed with ¼ round bur, and animals were sacrificed at 0, 6, 9, 12, 24, 48, and 72 h. The exposed teeth were obtained for real-time polymerase chain reaction (qRT-PCR) analysis and histological and immunohistochemistry (IHC) analysis.

RESULTS

Histological evaluation revealed a time-dependent steady increase in inflammation. Similar time-dependent increase in the expression of inflammatory cytokines was noted. Group A exhibited an increase in TLR-4, Dectin-1, and OPN at 6 h, while TLR-2 was expressed at 24 h. Group B expressed TLR-2, Dectin-1, and OPN at 9, 48, and 72 h, respectively (p ≤ 0.05). Expression of OPN and TNF-α exhibited a similar pattern in both groups. IHC also detected expression of TLR-2, Dectin-1, TLR4, and CD68 in some cells at 6 and 9 h.

CONCLUSIONS

NMRI mice provided for a stable pulp inflammation model. Zymosan may be used to develop pulp inflammation model and study inflammatory response towards fungal antigens. Dental pulp expressed Dectin-1 receptor. OPN and TNF-α exhibited a similar expression pattern.

CLINICAL RELEVANCE

Innate immunity of dental pulp is capable of detecting fungal pathogens.

Gene expression analysis of toll like receptor 2 and 4, Dectin-1, Osteopontin and inflammatory cytokines in human dental pulp ex-vivo

BACKGROUND

Toll like receptors (TLR) 2 and 4 present on innate immune cells of the dental pulp detect cariogenic bacteria. Along with bacteria, C. albicans may also be present in dental caries. The presence of C. albicans can be detected by Dectin-1 a C type Lectin receptor. Expression of Dectin-1 in human pulpits has not been reported. Similarly, cytokines are released as a consequence of dental pulp inflammation caused by cariogenic bacteria. The T helper (Th) 1 inflammatory response leads to exacerbation of inflammation and its relationship with Osteopontin (OPN) is not known in pulp inflammation.

OBJECTIVE

The aim of this study was to observe the expression of Dectin-1, TLR-2, OPN and pro-inflammatory cytokines in irreversibly inflamed human dental pulp and to observe relationship between Dectin-1/TLR-2 and OPN/Pro-inflammatory cytokines in the presence of appropriate controls.

METHODS

A total of 28 subjects diagnosed with irreversible pulpitis were included in this ex-vivo study. Fifteen samples were subjected to standard hematoxylin and Eosin (H&E) and immunohistochemistry staining. Whereas, gene expression analysis was performed on 13 samples to observe mRNA expression of pro-inflammatory cytokines; tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1 beta (ß), IL-6 Dectin-1, OPN, TLR-2 and TLR-4. SPSS version 21 was used for statistical analysis. One way analysis of variance (ANOVA), Pearson correlation and Chi-square test were used at p ≤ 0.05.

RESULTS

Gene expressions of Dectin-1, TLR-2 and TLR-4 were observed in all samples. Dectin-1 and TLR-2 expressions were significantly correlated (r = 0.5587, p = 0.0002). Similarly, OPN and TNF-α expression showed a significant correlation (r = 0.5860, p = 0001). The agreement between histologic and clinical diagnosis was 69.2% in the cases of irreversible pulpitis.

CONCLUSION

Dectin-1 was expressed by inflamed human dental pulp. Dectin-1 and TLR-2 expression pattern was suggestive of a collaborative receptor response in inflamed pulp environment. OPN and TNF-α expressions showed a positive correlation indicating a possible relationship.

Osteopontin: An important protein in the formation of kidney stones

The incidence of kidney stones averages 10%, and the recurrence rate of kidney stones is approximately 10% at 1 year, 35% at 5 years, 50% at 10 years, and 75% at 20 years. However, there is currently a lack of good medicines for the prevention and treatment of kidney stones. Osteopontin (OPN) is an important protein in kidney stone formation, but its role is controversial, with some studies suggesting that it inhibits stone formation, while other studies suggest that it can promote stone formation. OPN is a highly phosphorylated protein, and with the deepening of research, there is growing evidence that it promotes stone formation, and the phosphorylated protein is believed to have adhesion effect, promote stone aggregation and nucleation. In addition, OPN is closely related to immune cell infiltration, such as OPN as a pro-inflammatory factor, which can activate mast cells (degranulate to release various inflammatory factors), macrophages (differentiated into M1 macrophages), and T cells (differentiated into T1 cells) etc., and these inflammatory cells play a role in kidney damage and stone formation. In short, OPN mainly exists in the phosphorylated form in kidney stones, plays an important role in the formation of stones, and may be an important target for drug therapy of kidney stones.

Secreted phosphoprotein 1 promotes angiogenesis of glioblastoma through upregulating PSMA expression via transcription factor HIF-1&alpha;

Glioblastoma multiforme (GBM) is a highly vascularized malignant brain tumor. Our previous study showed that prostate-specific membrane antigen (PSMA) promotes angiogenesis of GBM. However, the specific mechanism underlying GBM-induced PSMA upregulation remains unclear. In this study, we demonstrate that the GBM-secreted cytokine phosphoprotein 1 (SPP1) can regulate the expression of PSMA in human umbilical vein endothelial cells (HUVECs). Our mechanistic study further reveals that SPP1 regulates the expression of PSMA through the transcription factor HIF1α. Moreover, SPP1 promotes HUVEC migration and tube formation. In addition, HIF1α knockdown reduces the expression of PSMA in HUVECs and blocks the ability of SPP1 to promote HUVEC migration and tube formation. We further confirm that SPP1 is abundantly expressed in GBM, is associated with poor prognosis, and has high clinical diagnostic value with considerable sensitivity and specificity. Collectively, our findings identify that the GBM-secreted cytokine SPP1 upregulates PSMA expression in endothelial cells via the transcription factor HIF1α, providing insight into the angiogenic process and promising candidates for targeted GBM therapy.

An integrin axis induces IFN-β production in plasmacytoid dendritic cells

Type I interferon (IFN) production by plasmacytoid dendritic cells (pDCs) has been mainly studied in the context of Toll-like receptor (TLR) activation. In the current report, we reveal that, in the absence of TLR activation, the integrin-binding SLAYGLR motif of secreted osteopontin (sOpn) induces IFN-β production in murine pDCs. This process is mediated by α4β1 integrin, indicating that integrin triggering may act as a subtle danger signal leading to IFN-β induction. The SLAYGLR-mediated α4 integrin/IFN-β axis is MyD88 independent and operates via a PI3K/mTOR/IRF3 pathway. Consequently, SLAYGLR-treated pDCs produce increased levels of type I IFNs following TLR stimulation. Intratumoral administration of SLAYGLR induces accumulation of IFN-β-expressing pDCs and efficiently suppresses melanoma tumor growth. In this process, pDCs are crucial. Finally, SLAYGLR enhances pDC development from bone marrow progenitors. These findings open new questions on the roles of sOpn and integrin α4 during homeostasis and inflammation. The newly identified integrin/IFN-β axis may be implicated in a wide array of immune responses.

Role of osteopontin (OPN) in uterine spiral artery remodeling

Uterine spiral artery (SpA) remodeling is critical for a successful pregnancy. The deficiency of SpA remodeling seriously affects the blood perfusion of the placenta, impacting the nutritional supply to the fetus and therefore fetal growth and development, which is one of the pathological causes of pregnancy related diseases. This process involves the interaction between all cells and related factors at the maternal-fetal interface, especially extravillous trophoblast cells (EVT), vascular smooth muscle cells (VSMCs) and decidual immune cells. Osteopontin (OPN), as a glycosylated protein, is widely localized in the extracellular matrix and participates in a variety of cellular activities such as migration, adhesion, differentiation and survival. OPN plays an important role in placental development, uterine decidualization and pregnancy success. This study focuses on the role of OPN in uterine spiral artery remodeling and its related molecular mechanism.

SPP1 in infliximab resistant ulcerative colitis and associated colorectal cancer: an analysis of differentially expressed genes

OBJECTIVE

Infliximab, a tumour necrosis factor-α (TNFα) antagonist, has advanced the management of ulcerative colitis. Although efficacious, considerable percentage of patients are resistant to treatment. Accumulative inflammatory burden in long-term ulcerative colitis patients refractory to therapy increases the risk of developing colorectal cancer (CRC). Our study investigated anti-TNFα-naïve patients with active ulcerative colitis to identify gene biomarkers whose dysregulated expression correlated with resistance to infliximab (IFX) treatment and poor prognosis in CRC.

METHODS

Differentially expressed genes (DEGs) from two studies (GSE73661 and GSE14580) with colonic mucosal samples were retrieved. Noninflammatory bowel disease controls were compared with those with active ulcerative colitis that either responded or were resistant to IFX before treatment. DEGs from ulcerative colitis samples resistant to IFX were used to construct a protein-protein interaction network, and clustering gene modules were identified. Module DEGs that overlapped with ulcerative colitis samples responsive to IFX were analysed, based on topological closeness and radiality. Hub genes were obtained, and their correlation with CRC progression was evaluated. Their expression in CRC tissues and their tumour microenvironment immune status was estimated.

RESULTS

Three clusters composed of 582 DEGs from ulcerative colitis samples resistant to IFX were retrieved. Comparative analysis identified 305 overlapping DEGs with ulcerative colitis samples responsive to IFX. Topological analysis revealed a hub gene - SPP1 - whose overexpression in CRC tissues and patients correlated with increased infiltration of immune signatures and poor prognosis.

CONCLUSION

SPP1 may serve as potential gene biomarker and predictor of resistance to IFX therapy in ulcerative colitis and CRC development.

Immune regulatory effect of osteopontin gene therapy in a murine model of multi-drug resistant pulmonary tuberculosis

Tuberculosis (TB) has been for many years a major public health problem since treatment is long and sometimes ineffective favoring the increase of multi-drug-resistant mycobacteria (MDR). Gene therapy is a novel and effective tool to regulate immune responses. In this study we evaluated the therapeutic effect of an adenoviral vector codifying osteopontin (AdOPN), a molecule known for their roles to favour Th1 and Th17 type-cytokine expression which are crucial in TB containment. A single-dose of AdOPN administration in BALB/c mice suffering late progressive pulmonary MDR-TB, produced significant lower bacterial load and pneumonia, due to higher expression of IFN-γ, IL-12 and IL-17 in coexistence with increase of granulomas in number and size, resulting in higher survival, in contrast with mice treated with the control adenovirus that codify the green fluorescent protein (AdGFP). Combined therapy of AdOPN with a regimen of 2nd line antibiotics produced a better control of bacterial load in lung during the first days of treatment, suggesting that AdOPN can shorten chemotherapy. Taken together, gene therapy with AdOPN leads to higher immune responses against TB infection, resulting in a new potential treatment against pulmonary TB that can co-adjuvant chemotherapy.

Osteopontin in autoimmune disorders: current knowledge and future perspective

Osteopontin (OPN) is a multifunctional cytokine and adhesion molecule, as well as an unusual regulator for both innate and adaptive immune responses. Several immune cells can produce OPN, including dendritic cells (DCs), macrophages, and T lymphocytes. OPN expression is reported to be increased in a wide range of disorders, including autoimmunity, cancer, and allergy. The overexpression of OPN in several autoimmune disorders, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), Type 1 diabetes (T1D), inflammatory bowel disease (IBD), Sjögren's, and myasthenia gravis, have been shown to be correlated with disease severity. Regarding the important regulatory roles of OPN in the immune system, this study aimed to review the role of this molecule in autoimmune disorders and to provide a complete view of the current knowledge in this field.

Possible causes of atherosclerosis: lncRNA COLCA1 induces oxidative stress in human coronary artery endothelial cells and impairs wound healing

Background

Atherosclerosis is the most common cause of cardiovascular disease, accompanied by high mortality and poor prognosis. Low-density lipoprotein (LDL) and its oxidized form oxidized low-density lipoprotein (oxLDL) play an important role in atherosclerosis. This article will explore the role of the lncRNA COLCA1 (colorectal cancer associated 1)/hsa-miR-371a-5p/SPP1 (secreted phosphoprotein 1) pathway in oxLDL in causing human coronary artery endothelial cells (HCAECs) inflammation and related biological function changes.

Methods

OxLDL was used to stimulate HCAECs. The inflammatory response and biological function changes of HCAECs were analyzed, total RNA-seq was performed on HCAECs before and after stimulation, and RT-Qpcr (real-time quantitative PCR) was used to verify the differential genes. Interference of the expression of COLCA1 in HCAECs was performed by siRNA interference technology to verify the role of COLCA1 in the biological function changes of HCAECs after oxLDL stimulation, and further prove that COLCA1 affects SPP1 through hsa-miR-371a-5p.

Results

OxLDL can affect the oxidative stress response of HCAECs, which in turn affects the apoptosis and wound healing ability of HCAECs. COLCA1 and SPP1 were highly expressed after oxLDL stimulation, while hsa-miR-371a-5p was the opposite. After COLCA1 interference, the oxidative stress level of HCAECs stimulated by oxLDL decreased, the apoptosis level also significantly decreased, and the wound healing ability was enhanced. After simultaneous COLCA1 interference and recovery of the expression of hsa-miR-371a-5p, these improved functions disappeared. The dual-luciferase assay confirmed that hsa-miR-371a-5p and COLCA1, hsa-miR-371a-5p and SPP1 has binding targets.

Conclusions

OxLDL can up-regulate the expression of COLCA1 in HCAECs, which in turn affects the intracellular COLCA1/hsa-miR-371a-5p/SPP1 pathway to regulate the level of oxidative stress in cells. This in turn affects the level of apoptosis and wound healing ability, which causes cells to produce a continuous inflammatory response.

Secreted osteopontin from CD4+ T cells limits acute graft-versus-host disease

Osteopontin (OPN) has been considered a potential biomarker of graft-versus-host disease (GVHD). However, the function of OPN in GVHD is still elusive. Using a mouse model of acute GVHD (aGVHD), we report that OPN generated by CD4+ T cells is sufficient to exert a beneficial effect in controlling aGVHD through limiting gastrointestinal pathology, a major target organ of aGVHD. CD4+ T cell-derived OPN works on CD44 expressed in intestinal epithelial cells (IECs) and abates cell death of IECs. OPN also modulates gut microbiota with enhanced health-associated commensal bacteria Akkermansia. Importantly, we use our in vivo mouse mutant model to specifically express OPN isoforms and demonstrate that secreted OPN (sOPN), not intracellular OPN (iOPN), is solely responsible for the protective role of OPN. This study demonstrates that sOPN generated by CD4+ T cells is potent enough to limit aGVHD.

Both Full-Length and Protease-Cleaved Products of Osteopontin Are Elevated in Infectious Diseases

Circulating full-length osteopontin (FL-OPN) is elevated in plasma from patients with various infectious diseases, such as adult T-cell leukemia, Mycobacterium tuberculosis (TB), hepatitis virus infection, leptospirosis, acquired immune deficiency syndrome (AIDS), AIDS/TB, and coronavirus disease 2019 (COVID-19). Proteolysis of OPN by thrombin, matrix metalloproteases, caspase 8/3, cathepsin D, plasmin, and enterokinase generates various cleaved OPNs with a variety of bioactivities by binding to different target cells. Moreover, OPN is susceptible to gradual proteolysis. During inflammation, one of the cleaved fragments, N-terminal thrombin-cleaved OPN (trOPN or OPN-Arg¹⁶⁸ [OPN-R]), induces dendritic cell (DC) adhesion. Further cleavage by carboxypeptidase B2 or carboxypeptidase N removes Arg¹⁶⁸ from OPN-R to OPN-Leu¹⁶⁷ (OPN-L). Consequently, OPN-L decreases DC adhesion. In particular, the differences in plasma level over time are observed between FL-OPN and its cleaved OPNs during inflammation. We found that the undefined OPN levels (mixture of FL-OPN and cleaved OPN) were elevated in plasma and reflected the pathology of TB and COVID-19 rather than FL-OPN. These infections are associated with elevated levels of various proteases. Inhibition of the cleavage or the activities of cleaved products may improve the outcome of the therapy. Research on the metabolism of OPN is expected to create new therapies against infectious diseases.

A literature review on lactopontin and its roles in early life

OBJECTIVE

Our study aims to review the functions and possible mechanisms of lactopontin (LPN) in early life.

BACKGROUND

Human milk proteins provide a variety of protection and health benefits in early life. One of these multifunctional proteins is LPN, which is osteopontin (OPN) derived from milk.

METHODS

Information used to write this paper was collected from Uniprot, PubMed, and Google Scholar, including in vitro, in vivo, and clinical studies.

CONCLUSIONS

LPN is a highly phosphorylated, O-glycosylated acidic protein and a unique type of OPN, as it presents at the highest concentration and a higher degree of posttranslational modifications (PTMs) in human milk than other tissues and excretions. LPN is present in milk and the intestinal tracts of infants after consumption as a mixture of intact protein and peptides, which can bind diverse integrin and receptors in the target cell and drive downstream signaling pathways. LPN is found to play important roles in developing the immune, intestinal and nervous systems in early life. Moreover, LPN has also shown to support preterm infants' health when they are especially vulnerable after delivery via animal studies. Additionally, LPN can form protein complex with another milk bioactive protein, lactoferrin (LF), to withstand proteolysis and perform more efficient biological activity. Therefore, LPN showed great potential for early life while more clinical trials and evidence are still emergying.

Single-Cell Profiling Reveals Transcriptional Signatures and Cell-Cell Crosstalk in Anti-PLA2R Positive Idiopathic Membranous Nephropathy Patients

Idiopathic membranous nephropathy (IMN) is an organ-specific autoimmune disease of the kidney glomerulus. It may gradually progress to end-stage renal disease (ESRD) characterized by increased proteinuria, which leads to serious consequences. Although substantial advances have been made in the understanding of the molecular bases of IMN in the last 10 years, certain questions remain largely unanswered. To define the transcriptomic landscape at single-cell resolution, we analyzed kidney samples from 6 patients with anti-PLA2R positive IMN and 2 healthy control subjects using single-cell RNA sequencing. We then identified distinct cell clusters through unsupervised clustering analysis of kidney specimens. Identification of the differentially expressed genes (DEGs) and enrichment analysis as well as the interaction between cells were also performed. Based on transcriptional expression patterns, we identified all previously described cell types in the kidney. The DEGs in most kidney parenchymal cells were primarily enriched in genes involved in the regulation of inflammation and immune response including IL-17 signaling, TNF signaling, NOD-like receptor signaling, and MAPK signaling. Moreover, cell-cell crosstalk highlighted the extensive communication of mesangial cells, which infers great importance in IMN. IMN with massive proteinuria displayed elevated expression of genes participating in inflammatory signaling pathways that may be involved in the pathogenesis of the progression of IMN. Overall, we applied single-cell RNA sequencing to IMN to uncover intercellular interactions, elucidate key pathways underlying the pathogenesis, and identify novel therapeutic targets of anti-PLA2R positive IMN.

Curcumin: A Dietary Phytochemical for Targeting the Phenotype and Function of Dendritic Cells

Dendritic cells (DCs) are the most powerful antigen-presenting cells which link the innate and adaptive immune responses. Depending on the context, DCs initiate the immune responses or contribute to immune tolerance. Any disturbance in their phenotypes and functions may initiate inflammatory or autoimmune diseases. Hence, dysregulated DCs are the most attractive pharmacological target for the development of new therapies aiming at reducing their immunogenicity and at enhancing their tolerogenicity. Curcumin is the polyphenolic phytochemical component of the spice turmeric with a wide range of pharmacological activities. It acts in several ways as a modulator of DCs and converts them into tolerogenic DCs. Tolerogenic DCs possess anti-inflammatory and immunomodulatory activities that regulate the immune responses in health and disease. Curcumin by blocking maturation markers, cytokines and chemokines expression, and disrupting the antigen-presenting machinery of DCs render them non- or hypo-responsive to immunostimulants. It also reduces the expression of co-stimulatory and adhesion molecules on DCs and prevents them from both migration and antigen presentation but enhances their endocytosis capacity. Hence, curcumin causes DCs-inducing regulatory T cells and dampens CD4+ T helper 1 (Th1), Th2, and Th17 polarization. Inhibition of transcription factors such as NF-κB, AP-1, MAPKs (p38, JNK, ERK) and other intracellular signaling molecules such as JAK/STAT/SOCS provide a plausible explanation for most of these observations. In this review, we summarize the potential effects of curcumin on the phenotypes and functions of DCs as the key players in orchestration, stimulation, and modulation of the immune responses.

Dietary osteopontin-enriched algal protein as nutritional support in weaned pigs infected with F18-fimbriated enterotoxigenic Escherichia coli

This study investigated the effects of dietary osteopontin (OPN)-enriched algal protein on growth, immune status, and fecal fermentation profiles of weaned pigs challenged with a live infection of F18-fimbriated enterotoxigenic E. coli (ETEC). At 21 d of age, 54 pigs (5.95 ± 0.28 kg BW; blocked by BW) were allotted to 1 of 3 experimental groups combining dietary and health statuses. A control diet, containing 1% wild-type algal protein, was fed to both sham-inoculated (NC) and ETEC-inoculated (PC) pigs, while the test diet contained 1% OPN-enriched algal protein as fed only to ETEC-inoculated pigs (OA). All pigs received their assigned dietary treatment starting at study initiation to permit a 10-d acclimation period prior to inoculation. Growth performance, fecal dry matter, as well as hematological, histopathological, immune, and microbiota outcomes were analyzed by ANOVA, where treatment and time were considered as fixed effects and pig as a random effect; significance was accepted at P < 0.05. Overall, ETEC-inoculated pigs (PC and OA) exhibited decreased (P < 0.05) ADG and G:F, as well as increased (P < 0.05) peripheral blood helper T-cells and total leukocyte counts, compared with NC pigs during the postinoculation period. The OA treatment also elicited the highest (P < 0.05) concentrations of circulating tumor necrosis factor-α and volatile fatty acid concentrations in luminal contents at various postinoculation time-points, compared with other treatments. A principal coordinate analysis based on Unifrac weighted distances indicated that NC and OA groups had similar overall bacterial community structures, while PC pigs exhibited greater diversity, but infection status had no impact on α-diversity. Osteopontin-specific effects on microbial community structure included enrichment within Streptococcus and Blautia genera and decreased abundance of 12 other genera as compared with PC pigs. Overall, ETEC-infected pigs receiving 1% OPN-enriched algal protein exhibited changes immunity, inflammatory status, and colonic microbial community structure that may benefit weanling pigs experiencing F18 ETEC infection.

Tau Pathology Drives Dementia Risk-Associated Gene Networks toward Chronic Inflammatory States and Immunosuppression

To understand how neural-immune-associated genes and pathways contribute to neurodegenerative disease pathophysiology, we performed a systematic functional genomic analysis in purified microglia and bulk tissue from mouse and human AD, FTD, and PSP. We uncover a complex temporal trajectory of microglial-immune pathways involving the type 1 interferon response associated with tau pathology in the early stages, followed by later signatures of partial immune suppression and, subsequently, the type 2 interferon response. We find that genetic risk for dementias shows disease-specific patterns of pathway enrichment. We identify drivers of two gene co-expression modules conserved from mouse to human, representing competing arms of microglial-immune activation (NAct) and suppression (NSupp) in neurodegeneration. We validate our findings by using chemogenetics, experimental perturbation data, and single-cell sequencing in post-mortem brains. Our results refine the understanding of stage- and disease-specific microglial responses, implicate microglial viral defense pathways in dementia pathophysiology, and highlight therapeutic windows.

Rexach et al. use transcriptional network analysis to define dynamic microglial transitions across neurodegeneration, discovering that three dementias with tau pathology involve dysregulated microglial viral and antiviral pathways. Bio-informatics coupled with experimental validation identifies regulatory drivers, implicating double-stranded RNA and interferon-response genes as drivers of early immune suppression in disease.

Osteopontin contributes to late-onset asthma phenotypes in adult asthma patients

Patients with late-onset asthma (LOA) have poor clinical outcomes. Osteopontin (OPN) is associated with airway inflammation and remodeling. To investigate the role of OPN in LOA compared to early-onset asthma (EOA), serum OPN levels were compared between 131 adult asthma patients (48 LOA and 83 EOA patients) and 226 healthy controls (HCs). BALB/c mice were sensitized with ovalbumin with/without polyinosinic-polycytidylic acid (poly(I:C)) from week 6 (A6 mice) or week 12 (A12 mice) after birth. Airway hyperresponsiveness (AHR), bronchoalveolar lavage fluid (BALF), cell counts, histology, and Spp1 expression were assessed. The levels of OPN, transforming growth factor β1 (TGF-β1), chitinase 3-like 1 (CH3L1), and interleukin (IL) 5 were measured by ELISA. The expression of Smad3 phosphorylation and tissue transglutaminase 2 (TGM2) was evaluated by Western blot. The serum OPN levels were significantly higher in asthma patients than in HCs and in LOA patients than in those with EOA (P < 0.05) and were positively correlated with serum TGF-β1 and CH3L1 (r = 0.174, r = 0.264; P < 0.05). A12 mice showed elevated AHR with increased levels of OPN/TGF-β1/IL-5 in BALF and Spp1 compared to A6 mice. Poly(I:C) induced remarkable TGF-β1, CH3L1, Th2 cytokine, and OPN levels in BALF and the expression of phosphorylated Smad3, TGM2, and Spp1 in the lungs. OPN triggered TGF-β1/Smad3 signaling in the lungs, which was suppressed by dexamethasone and anti-IL5 antibody. In conclusion, aging and exposure to viral infections may induce OPN release and consequently modulate inflammation and TGF-β1/Smad3-related remodeling, contributing to the development of LOA.

Aging and viral infections in older individuals may combine to spur the release of an inflammatory protein implicated in late-onset asthma. A team led by Hae-Sim Park from Ajou University School of Medicine, Suwon, South Korea, showed that people who develop asthma after age 40 have higher blood levels of osteopontin, a multifunctional protein with roles in airway inflammation and tissue remodeling, than people who develop asthma at a younger age or healthy individuals. The researchers developed two ovalbumin-induced asthma models in younger and older mice, and found that older mice developed more severe airway hyperresponsiveness with higher levels of osteopontin, among other inflammatory markers, which were emnhanced by viral infection. Drug therapies that target osteopontin signaling could help combat the late-onset asthma.

NLRP3 gain-of-function in CD4+ T lymphocytes ameliorates experimental autoimmune encephalomyelitis

NLRP3 inflammasome [NLR (nucleotide-binding domain, leucine-rich repeat containing protein) Pyrin-domain-containing 3 ] functions as an innate sensor of several PAMPs and DAMPs (pathogen- and damage-associated molecular patterns). It has been also reported as a transcription factor related to Th2 pattern, although its role in the adaptive immunity has been controversial, mainly because the studies were performed using gene deletion approaches. In the present study, we have investigated the NLRP3 gain-of-function in the context of encephalomyelitis autoimmune disease (EAE), considered to be a Th1- and Th17-mediated disease. We took advantage of an animal model with NLRP3 gain-of-function exclusively to T CD4⁺ lymphocytes (CD4CreNLRP3fl/fl). These mice presented reduced clinical score, accompanied by less infiltrating T CD4⁺ cells expressing both IFN-γ and IL-17 at the central nervous system (CNS) during the peak of the disease. However, besides NLRP3 gain-of-function in lymphocytes, these mice lack NLRP3 expression in non-T CD4⁺ cells. Therefore, in order to circumvent this deficiency, we transferred naive CD4⁺ T cells from WT, NLRP3-/- or CD4CreNLRP3fl/fl into Rag-1-/- mice and immunized them with MOG_35-55 Likewise, the animals repopulated with CD4CreNLRP3fl/fl T CD4⁺ cells presented reduced clinical score and decreased IFN-γ production at the peak of the disease. Additionally, primary effector CD4⁺ T cells derived from these mice presented reduced glycolytic profile, a metabolic profile compatible with Th2 cells. Finally, naive CD4⁺ T cells from CD4CreNLRP3fl/fl mice under a Th2-related cytokine milieu cocktail exhibited in vitro an increased IL-4 and IL-13 production. Conversely, naive CD4⁺ T cells from CD4CreNLRP3fl/fl mice under Th1 differentiation produced less IFN-γ and T-bet. Altogether, our data evidence that the NLRP3 gain-of-function promotes a Th2-related response, a pathway that could be better explored in the treatment of multiple sclerosis.

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.

Osteopontin protects against pneumococcal infection in a murine model of allergic airway inflammation

BACKGROUND

In atopic asthma, chronic Th2-biased inflammation is associated with an increased risk of pneumococcal infection. The anionic phosphoglycoprotein osteopontin (OPN) is highly expressed in asthma and has been ascribed several roles during inflammation. This study aimed to investigate whether OPN affects inflammation and vulnerability to pneumococcal infection in atopic asthma.

METHODS

House dust mite (HDM) extract was used to induce allergic airway inflammation in both wild-type (Spp1^+/+ ) and OPN knockout (Spp1^-/- ) C57BL/6J mice, and the airway was then infected with Streptococcus pneumoniae. Parameters reflecting inflammation, tissue injury, and bacterial burden were measured. In addition, samples from humans with allergic asthma were analyzed.

RESULTS

Both allergen challenge in individuals with allergic asthma and the intranasal instillation of HDM in mice resulted in increased OPN levels in bronchoalveolar lavage fluid (BALF). More immune cells (including alveolar macrophages, neutrophils, eosinophils, and lymphocytes) and higher levels of proinflammatory cytokines were found in Spp1^-/- mice than in Spp1^+/+ mice. Moreover, OPN-deficient mice exhibited increased levels of markers reflecting tissue injury. Upon infection with S. pneumoniae, Spp1^+/+ mice with allergic airway inflammation had a significantly lower bacterial burden in both BALF and lung tissue than did Spp1^-/- mice. Furthermore, Spp1^-/- mice had higher levels of cytokines and immune cells in BALF than did Spp1^+/+ mice.

CONCLUSION

OPN reduces inflammation, decreases tissue injury, and reduces bacterial loads during concurrent pneumococcal infection and allergic airway inflammation in a murine model. These findings suggest that OPN significantly affects vulnerability to pneumococcal infection in atopic asthma.

Bovine Derived in vitro Cultures Generate Heterogeneous Populations of Antigen Presenting Cells

Antigen presenting cells (APC) of the mononuclear phagocytic system include dendritic cells (DCs) and macrophages (Macs) which are essential mediators of innate and adaptive immune responses. Many of the biological functions attributed to these cell subsets have been elucidated using models that utilize in vitro-matured cells derived from common progenitors. However, it has recently been shown that monocyte culture systems generate heterogeneous populations of cells, DCs, and Macs. In light of these findings, we analyzed the most commonly used bovine in vitro-derived APC models and compared them to bona fide DCs. Here, we show that bovine monocyte-derived DCs and Macs can be differentiated on the basis of CD11c and MHC class II (MHCII) expression and that in vitro conditions generate a heterologous group of both DCs and Macs with defined and specific biological activities. In addition, skin-migrating macrophages present in the bovine afferent lymph were identified and phenotyped for the first time. RNA sequencing analyses showed that these monophagocytic cells have distinct transcriptomic profiles similar to those described in other species. These results have important implications for the interpretation of data obtained using in vitro systems.

Discrepancies in the Tumor Microenvironment of Spontaneous and Orthotopic Murine Models of Pancreatic Cancer Uncover a New Immunostimulatory Phenotype for B Cells

B cells are salient features of pancreatic ductal adenocarcinoma (PDAC) tumors, yet their role in this disease remains controversial. Murine studies have indicated a protumoral role for B cells, whereas clinical data show tumor-infiltrating B cells are a positive prognostic factor, both in PDAC and other cancers. This disparity needs to be clarified in order to develop effective immunotherapies. In this study, we provide new evidence that reconcile human and mouse data and highlight the importance of using relevant preclinical tumor models when assessing B cell function. We compared B cell infiltration and activation in both a genetic model of murine PDAC (KPC mouse) and an injectable orthotopic model. A pronounced B cell infiltrate was only observed in KPC tumors and correlated with T cell infiltration, mirroring human disease. In contrast, orthotopic tumors exhibited a relative paucity of B cells. Accordingly, KPC-derived B cells displayed markers of B cell activation (germinal center entry, B cell memory, and plasma cell differentiation) accompanied by significant intratumoral immunoglobulin deposition, a feature markedly weaker in orthotopic tumors. Tumor immunoglobulins, however, did not appear to form immune complexes. Furthermore, in contrast to the current paradigm that tumor B cells are immunosuppressive, when assessed as a bulk population, intratumoral B cells upregulated several proinflammatory and immunostimulatory genes, a distinctly different phenotype to that of splenic-derived B cells; further highlighting the importance of studying tumor-infiltrating B cells over B cells from secondary lymphoid organs. In agreement with the current literature, genetic deletion of B cells (μMT mice) resulted in reduced orthotopic tumor growth, however, this was not recapitulated by treatment with B-cell-depleting anti-CD20 antibody and, more importantly, was not observed in anti-CD20-treated KPC mice. This suggests the result from B cell deficient mice might be caused by their altered immune system, rather than lack of B cells. Therefore, our data indicate B cells do not favor tumor progression. In conclusion, our analysis of relevant preclinical models shows B cells to be active members of the tumor microenvironment, producing immunostimulatory factors that might support the adaptive antitumor immune response, as suggested by human PDAC studies.

Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target

Glioblastoma is highly enriched with macrophages, and osteopontin (OPN) expression levels correlate with glioma grade and the degree of macrophage infiltration; thus, we studied whether OPN plays a crucial role in immune modulation. Quantitative PCR, immunoblotting, and ELISA were used to determine OPN expression. Knockdown of OPN was achieved using complementary siRNA, shRNA, and CRISPR/Cas9 techniques, followed by a series of in vitro functional migration and immunological assays. OPN gene-deficient mice were used to examine the roles of non-tumor-derived OPN on survival of mice harboring intracranial gliomas. Patients with mesenchymal glioblastoma multiforme (GBM) show high OPN expression, a negative survival prognosticator. OPN is a potent chemokine for macrophages, and its blockade significantly impaired the ability of glioma cells to recruit macrophages. Integrin αvβ5 (ITGαvβ5) is highly expressed on glioblastoma-infiltrating macrophages and constitutes a major OPN receptor. OPN maintains the M2 macrophage gene signature and phenotype. Both tumor-derived and host-derived OPN were critical for glioma development. OPN deficiency in either innate immune or glioma cells resulted in a marked reduction in M2 macrophages and elevated T cell effector activity infiltrating the glioma. Furthermore, OPN deficiency in the glioma cells sensitized them to direct CD8+ T cell cytotoxicity. Systemic administration in mice of 4-1BB-OPN bispecific aptamers was efficacious, increasing median survival time by 68% (P < 0.05). OPN is thus an important chemokine for recruiting macrophages to glioblastoma, mediates crosstalk between tumor cells and the innate immune system, and has the potential to be exploited as a therapeutic target.

Raw cow's milk consumption and allergic diseases - The potential role of bioactive whey proteins

The prevalence of allergic diseases has increased significantly in Western countries in the last decades. This increase is often explained by the loss of rural living conditions and associated changes in diet and lifestyle. In line with this 'hygiene hypothesis', several epidemiological studies have shown that growing up on a farm lowers the risk of developing allergic diseases. The consumption of raw, unprocessed, cow's milk seems to be one of the factors contributing to this protective effect. Recent evidence indeed shows an inverse relation between raw cow's milk consumption and the development of asthma and allergies. However, the consumption of raw milk is not recommended due to the possible contamination with pathogens. Cow's milk used for commercial purposes is therefore processed, but this milk processing is shown to abolish the allergy-protective effects of raw milk. This emphasizes the importance of understanding the components and mechanisms underlying the allergy-protective capacity of raw cow's milk. Only then, ways to produce a safe and protective milk can be developed. Since mainly heat treatment is shown to abolish the allergy-protective effects of raw cow's milk, the heat-sensitive whey protein fraction of raw milk is an often-mentioned source of the protective components. In this review, several of these whey proteins, their potential contribution to the allergy-protective effects of raw cow's milk and the consequences of heat treatment will be discussed. A better understanding of these bioactive whey proteins might eventually contribute to the development of new nutritional approaches for allergy management.

Regulatory Roles of Osteopontin in Production of Monocyte-Origin MCP-1

Osteopontin (OPN), expressed by various immune cells, plays a critical role in leukocyte migration. Although OPN was found to selectively induce the expression of proinflammatory chemokines, the molecular mechanisms that control OPN gene expression and its underlying mechanism for migration and recruitment of inflammatory cells remain largely unknown. In this study, real-time polymerase chain reaction and enzyme-linked immunosorbent assay were used to determine OPN and monocyte chemoattractant protein 1 (MCP-1) expression. Signaling and molecular events between OPN and MCP-1 were analyzed by Western blot. Leukocyte migration in the presence of OPN was measured by chemotaxis assay. Our data indicated that phosphoinositide 3-kinase (PI3K), c-Jun NH2-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) that are activated upon stimulation with lipopolysaccharide were shown to upregulate OPN expression. Endogenous production of OPN was attributable to increased production of MCP-1, and this effect could be blocked by an anti-β1 integrin antibody and JNK and p38 kinase inhibitors. Furthermore, we found that the effect of OPN on inflammatory cell migration was mediated through inducing the expression of MCP-1 in monocytes. These results support a role of OPN in monocyte migration via MCP-1, which may represent an additional mechanism for innate and adaptive immune responses.

Assessing the Feasibility of Neutralizing Osteopontin with Various Therapeutic Antibody Modalities

Osteopontin is a secreted glycophosphoprotein that is highly implicated in many physiological and pathological processes such as biomineralization, cell-mediated immunity, inflammation, fibrosis, cell survival, tumorigenesis and metastasis. Antibodies against osteopontin have been actively pursued as potential therapeutics for various diseases by pharmaceutical companies and academic laboratories. Many studies have demonstrated the efficacy of osteopontin inhibition in a variety of preclinical models of diseases such as rheumatoid arthritis, cancer, nonalcoholic steatohepatitis, but clinical utility has not yet been demonstrated. To evaluate the feasibility of osteopontin neutralization with antibodies in a clinical setting, we measured its physiological turnover rate in humans, a sensitive parameter required for mechanistic pharmacokinetic and pharmacodynamic (PK/PD) modeling of biotherapeutics. Results from a stable isotope-labelled amino acid pulse-chase study in healthy human subjects followed by mass spectrometry showed that osteopontin undergoes very rapid turnover. PK/PD modeling and simulation of different theoretical scenarios reveal that achieving sufficient target coverage using antibodies can be very challenging mostly due to osteopontin’s fast turnover, as well as its relatively high plasma concentrations in human. Therapeutic antibodies against osteopontin would need to be engineered to have much extended PK than conventional antibodies, and be administered at high doses and with short dosing intervals.

Methylglyoxal-bis-guanylhydrazone inhibits osteopontin expression and differentiation in cultured human monocytes

Monocyte activation and polarization play essential roles in many chronic inflammatory diseases. An imbalance of M1 and M2 macrophage activation (pro-inflammatory and alternatively activated, respectively) is believed to be a key aspect in the etiology of these diseases, thus a therapeutic approach that regulates macrophage activation could be of broad clinical relevance. Methylglyoxal-bis-guanylhydrazone (MGBG), a regulator of polyamine metabolism, has recently been shown to be concentrated in monocytes and macrophages, and interfere with HIV integration into the DNA of these cells in vitro. RNA expression analysis of monocytes from HIV+ and control donors with or without MGBG treatment revealed the only gene to be consistently down regulated by MGBG to be osteopontin (OPN). The elevated expression of this pro-inflammatory cytokine and monocyte chemoattractant is associated with various chronic inflammatory diseases. We demonstrate that MGBG is a potent inhibitor of secreted OPN (sOPN) in cultured monocytes with 50% inhibition achieved at 0.1 μM of the drug. Furthermore, inhibition of OPN RNA transcription in monocyte cultures occurs at similar concentrations of the drug. During differentiation of monocytes into macrophages in vitro, monocytes express cell surface CD16 and the cells undergo limited DNA synthesis as measured by uptake of BrdU. MGBG inhibited both activities at similar doses to those regulating OPN expression. In addition, monocyte treatment with MGBG inhibited differentiation into both M1 and M2 classes of macrophages at non-toxic doses. The inhibition of differentiation and anti-OPN effects of MGBG were specific for monocytes in that differentiated macrophages were nearly resistant to MGBG activities. Thus MGBG may have potential therapeutic utility in reducing or normalizing OPN levels and regulating monocyte activation in diseases that involve chronic inflammation.

Osteopontin Promotes Protective Antigenic Tolerance against Experimental Allergic Airway Disease

In the context of inflammation, osteopontin (Opn) is known to promote effector responses, facilitating a proinflammatory environment; however, its role during antigenic tolerance induction is unknown. Using a mouse model of asthma, we investigated the role of Opn during antigenic tolerance induction and its effects on associated regulatory cellular populations prior to disease initiation. Our experiments demonstrate that Opn drives protective antigenic tolerance by inducing accumulation of IFN-β-producing plasmacytoid dendritic cells, as well as regulatory T cells, in mediastinal lymph nodes. We also show that, in the absence of TLR triggers, recombinant Opn, and particularly its SLAYGLR motif, directly induces IFN-β expression in Ag-primed plasmacytoid dendritic cells, which renders them extra protective against induction of allergic airway disease upon transfer into recipient mice. Lastly, we show that blockade of type I IFNR prevents antigenic tolerance induction against experimental allergic asthma. Overall, we unveil a new role for Opn in setting up a tolerogenic milieu boosting antigenic tolerance induction, thus leading to prevention of allergic airway inflammation. Our results provide insight for the future design of immunotherapies against allergic asthma.

Is Osteopontin a Friend or Foe of Cell Apoptosis in Inflammatory Gastrointestinal and Liver Diseases?

Osteopontin (OPN) is involved in a variety of biological processes, including bone remodeling, innate immunity, acute and chronic inflammation, and cancer. The expression of OPN occurs in various tissues and cells, including intestinal epithelial cells and immune cells such as macrophages, dendritic cells, and T lymphocytes. OPN plays an important role in the efficient development of T helper 1 immune responses and cell survival by inhibiting apoptosis. The association of OPN with apoptosis has been investigated. In this review, we described the role of OPN in inflammatory gastrointestinal and liver diseases, focusing on the association of OPN with apoptosis. OPN changes its association with apoptosis depending on the type of disease and the phase of disease activity, acting as a promoter or a suppressor of inflammation and inflammatory carcinogenesis. It is essential that the roles of OPN in those diseases are elucidated, and treatments based on its mechanism are developed.

A systematic review and meta-analysis of HCV clearance

While hepatitis C exemplifies the role of host genetics in infectious diseases outcomes, there is no comprehensive overview of polymorphisms influencing spontaneous and/or treatment-induced hepatitis C virus clearance. We performed a systematic review and meta-analysis of host polymorphisms associated with these phenotypes. Literature search was conducted using combinations of keywords in three databases. Studies were reviewed and relevant data systematically extracted for subsequent meta-analyses. Polymorphisms from candidate gene studies were tested in two cohorts of HCV-infected patients with available genomic data. The literature search yielded 8'294 citations, among which 262 studies were selected. In the meta-analysis of 27 HLA studies, the most significant associations with spontaneous hepatitis C virus clearance included DQB1*02, DQB1*03, DRB1*04 and DRB1*11. In the meta-analysis of 16 studies of KIR genes and their HLA-ligands, KIR2DS3 was associated with both spontaneous and treatment-induced clearance, and the HLA-C2 ligand with failure to spontaneously clear the virus. In a pooled analysis of 105 candidate genes and two genome-wide association studies, we observed associations of single nucleotide polymorphisms from nine genes (EIF2AK2, IFNAR2, ITPA, MBL2, MX1, OASL, SPP1, TGFB1, TNK2) with response to interferon-based therapy. Meta-analysis of 141 studies confirmed the association of IFNL3/4 polymorphisms with spontaneous and treatment-induced hepatitis C virus clearance, even in previously underpowered groups, such as hepatitis C virus genotypes 2/3-infected patients. This study may contribute to a better understanding of hepatitis C virus immunopathogenesis and highlights the complex role of host genetics in hepatitis C virus clearance.

Osteopontin at the Crossroads of Inflammation and Tumor Progression

Complex interactions between tumor and host cells regulate systemic tumor dissemination, a process that begins early at the primary tumor site and goes on until tumor cells detach themselves from the tumor mass and start migrating into the blood or lymphatic vessels. Metastatic cells colonize the target organs and are capable of surviving and growing at distant sites. In this context, osteopontin (OPN) appears to be a key determinant of the crosstalk between cancer cells and the host microenvironment, which in turn modulates immune evasion. OPN is overexpressed in several human carcinomas and has been implicated in inflammation, tumor progression, and metastasis. Thus, it represents one of the most attracting targets for cancer therapy. Within the tumor mass, OPN is secreted in various forms either by the tumor itself or by stroma cells, and it can exert either pro- or antitumorigenic effects according to the cell type and tumor microenvironment. Thus, targeting OPN for therapeutic purposes needs to take into account the heterogeneous functions of the multiple OPN forms with regard to cancer formation and progression. In this review, we will describe the role of systemic, tumor-derived, and stroma-derived OPN, highlighting its pivotal role at the crossroads of inflammation and tumor progression.

Role of Osteopontin in Psoriasis: An Immunohistochemical Study

Background:

Osteopontin (OPN) has been postulated to have a role in several T-helper (Th) 1 and Th 17-mediated diseases including psoriasis (PS), through multiple mechanisms sharing in the onset and worsening of PS, OPN shares in induction of keratinocyte proliferation through inhibiting keratinocyte apoptosis, OPN acts as a proinflammatory agent that participates in the upregulation of Th cell lineages, among which are the Th 1 and Th 17 cells.

Aims and Objectives:

The aim of this study was to explore the possible role of OPN in the pathogenesis of PS.

Materials and Methods:

This case–control study was carried out on 18 patients of chronic plaque PS (mean age 37.61 ± 14.48) and a control group of 18 apparently healthy volunteers (mean age 41.11 ± 11.02 years). Severity of PS was assessed using the PS area and severity index score. Two skin biopsies were taken from psoriatic patients. The first was taken from the lesional skin and the other from a counter apparently healthy site.

Results:

Our results showed statistically significant differences in the expression of OPN, between lesional and nonlesional skin as well as between nonlesional skin and control group (P ≤ 0.001). In addition, there was a significant difference in the expression of OPN, between control and lesional group.

Conclusions:

OPN involvement in PS enlarges the list of cytokines able to stimulate the inflammatory response in this disease, anti-OPN antibodies, may eventually become a useful therapeutic approach in PS.

Secreted Phosphoprotein 1 Promoter Genetic Variants Are Associated with the Response to Pegylated Interferon α Plus Ribavirin Combination Therapy in Egyptian Patients with Chronic Hepatitis C Virus Infection

Background/Aims

The T-helper 1 (TH1) immune reaction is essential for the eradication of hepatitis C virus (HCV) during pegylated interferon α (PEG-IFN-α)- and ribavirin (RBV)-based therapy in chronic HCV patients. Secreted phosphoprotein 1 (SPP1) was shown to be a crucial cytokine for the initiation of a TH1 immune response. We aimed to investigate whether SPP1 single nucleotide polymorphisms (SNPs) may influence sustained virological response (SVR) rates.

Methods

Two SNPs in the promoter region of SPP1 at the −443 C>T and −1748 G>A loci were genotyped in 100 patients with chronic HCV genotype 4 infection using a TaqMan SNP genotyping assay.

Results

Sixty-seven patients achieved a SVR, and 33 patients showed no SVR. Patients carrying the T/T genotype at the −443 locus showed a significantly higher SVR rate than those carrying the C/T or C/C genotype (83.67% vs 50.98%, p<0.001). At the −1748 locus, the SVR rate was significantly higher in patients with the G/G genotype than in those with the A/A genotype (88.89% vs 52.63%, p=0.028) and in patients with the G/A genotype than in those with the A/A genotype (85.29% vs 52.63%, p=0.001).

Conclusions

SPP1 SNPs at −443 C>T and −1748 G>A loci may be useful markers for predicting the response to PEG-IFN-α-2b plus RBV therapy in Egyptian patients with chronic HCV genotype 4 infection.

Increased chemokine (C-C motif) ligand 21 expression and its correlation with osteopontin in Graves' disease

Graves' disease (GD) is a chronic autoimmune process characterized by the production of auto-antibodies that presumably consequent to the lymphocytic infiltrates in the thyroid. Chemokine (C-C motif) ligand 21 (CCL21) is important for the circulation of CC-chemokine receptor 7 (CCR7)-expressing cells. Meanwhile, osteopontin (OPN) enhances the production of proinflammatory cytokines and chemokines through NF-κB and MAPK signaling pathways in GD. Although CCL21 has been reported to play a vital role in several autoimmune diseases, little is known about the relationship between CCL21 and GD development. This study aimed to detect the CCL21 level in GD and to examine the role of OPN in regulating CCL21 production. 40 initial GD patients, 15 euthyroid GD patients, 12 TRAb-negative GD patients, and 25 healthy control donors were recruited. CCL21 levels in plasma and culture supernatants were quantified by enzyme-linked immunosorbent assay (ELISA). CD4+ T cells were isolated from peripheral blood mononuclear cells using antibody-coated magnetic beads. Quantitative polymerase chain reaction was used to determine CCL21 expression levels in CD4+ T cells. We demonstrated for the first time that plasma CCL21 levels were overexpressed in GD patients and recovered in TRAb-negative GD patients. Moreover, CCL21 levels correlated with TRAb levels and plasma OPN concentrations. Furthermore, we demonstrated that recombinant OPN increased the expression of CCL21 in a dose- and time-dependent manner. These data indicated a clinical correlation between plasma CCL21 levels and GD. CCL21 could serve as a novel biomarker for GD as well as a potential target for TRAb-positive GD treatment.

Enhancement of the Immunostimulatory Functions of Ex Vivo-Generated Dendritic Cells from Early-Stage Colon Cancer Patients by Consecutive Exposure to Low Doses of Sequential-Kinetic-Activated IL-4 and IL-12. A Preliminary Study

Dendritic cells (DCs), specialized antigen-presenting cells bridging innate and adaptive immunity, play a crucial role in determining specific immune response to tumors. Because of their potent immunoregulatory capacities, DCs have been exploited in anticancer vaccination, with limited success thus far. This pilot study compared low-dose interleukin (IL)-4 and IL-12 prepared by sequential kinetic activation (SKA) with standard doses of the same recombinant human cytokines on functional activity of ex vivo–generated monocyte-derived (Mo) DCs from colon carcinoma patients and normal subjects. MoDCs were exposed to medium alone, SKA-IL-4 (0.5 fg/ml), or SKA-IL-12 (2 fg/ml), alone or consecutively combined, in parallel with rhIL-4 (50 ng/ml) and rhIL-12 (1 ng/ml). Primary allogeneic one-way mixed lymphocyte reaction (MLR) was the end point to assess in vitro T-lymphocyte proliferation in response to MoDCs, and secreted IL-12p70 and interferon-γ in MLR supernatants measured by ELISA to assay for T-helper 1–promoting MoDC phenotype. No single agent enhanced the compromised allostimulatory activity of MoDCs from colon cancer patients, unlike healthy donors. However, MoDCs from nonmetastatic colon cancer patients, after sequential exposure to SKA-IL-4 (48 hours) and SKA-IL-12 (24 hours), displayed increased T-cell stimulatory capacity by MLR and acquired driving T-helper 1 polarization activity, although less markedly than the effects induced by recombinant human cytokines or found in normal subjects. These results point to an immunomodulatory capacity of low-dose SKA-IL-4 and SKA-IL-12 and encourage further investigation to provide clues for the rational development of new and more effective immunotherapeutic strategies against cancer.

Osteopontin promotes dendritic cell maturation and function in response to HBV antigens

Purpose

Dendritic cells (DCs) play critical roles in promoting innate and adaptive immunity in microbial infection. Functional impairment of DCs may mediate the suppression of viral-specific T-cell immune response in chronic hepatitis B (CHB) patients. Osteopontin (OPN) is involved in several liver diseases and infectious diseases. However, whether OPN affects DC function in hepatitis B virus (HBV) infection is unknown.

Methods

Twenty CHB patients and 20 healthy volunteers were recruited. OPN secreted by DCs was compared. Peripheral blood mononuclear cells cultured with OPN antibody were examined to study the costimulatory molecular expression and interleukin (IL)-12 production of DCs after HBV antigenic stimulation. OPN-deficient mice were used to investigate the influence of OPN on DC maturation and function after HBV antigenic stimulation in vitro and in vivo. Exogenous OPN was administrated to further verify the functioning of DCs from CHB patients upon HBV antigenic stimulation.

Results

We found that OPN production of DCs from CHB patients was significantly lower than those from healthy volunteers. The absence of OPN impaired IL-12 production and costimulatory molecular expression of DCs upon stimulation with HBV antigens. Defective DC function led to reduced activation of Th1 response to HBV antigens. In addition, OPN deficiency in DCs reduced the HBV antigen-induced inflammatory response in the liver of mice. Importantly, OPN administration significantly promoted the maturation of DCs from CHB patients in vitro.

Conclusion

These findings suggested that OPN could improve the maturation and functioning of DCs in the immune response to HBV antigens, which might be useful to further improve the effect of DC vaccine.

Assessment of serum levels of osteopontin, selenium and prolactin in patients with psoriasis compared with healthy controls, and their association with psoriasis severity

BACKGROUND

The association between psoriasis and cardiovascular diseases is well documented, but the underlying mechanisms remain unknown. Overexpression of osteopontin (OPN) has been reported in the plasma of patients with psoriasis, with increased cardiovascular risk factors in these patients. Selenium compounds are effective in downregulating OPN expression.

OBJECTIVE

We investigated the levels of OPN, selenium and prolactin (PRL) in psoriasis, and their association with metabolic status in patients to identify a possible link between these markers and observed comorbidities.

METHODS

Plasma samples from 40 patients with psoriasis and 40 age- and sex-matched healthy controls (HCs) were collected for ELISA. The clinical significance of plasma OPN, selenium and PRL levels in patients compared with controls was analysed in relation to metabolic disorders.

RESULTS

There was no significant difference in median serum selenium levels between the two groups. Serum levels of PRL were not significantly different from those of HCs, but levels of OPN were significantly higher in patients with psoriasis than in HCs.

CONCLUSIONS

High plasma OPN is a predictor for occurrence of psoriasis. Our study showed that serum selenium and PRL were not decreased in patients with psoriasis, but there was a negative statistically significant correlation between OPN and selenium in all participants.

Bovine osteopontin modifies the intestinal transcriptome of formula-fed infant rhesus monkeys to be more similar to those that were breastfed

BACKGROUND

Osteopontin (OPN) is a multifunctional protein found in human milk at high concentration.

OBJECTIVE

The impact of supplemental bovine OPN on growth, body composition, and the jejunal transcriptome was assessed.

METHODS

Newborn rhesus monkeys were randomly assigned to be breastfed (n = 4) or to receive formula [formula fed (FF), n = 6] or formula supplemented with 125 mg/L of bovine OPN (bOPN, n = 6) for 3 mo. Jejunal mRNA was extracted and subjected to microarray analysis.

RESULTS

Growth was similar among all the treatment groups, but breastfed monkeys were ∼25% leaner at 3 mo. Pairwise comparisons demonstrated that 1017 genes were differentially expressed between breastfed and FF groups, 217 between breastfed and bOPN groups, and 119 between FF and bOPN groups. The data were also analyzed with the use of weighted gene coexpression network analysis, which revealed 6 modules of coexpressed genes that differed among the 3 treatments. Nearly 50% of genes were assigned to one module in which breastfed differed from FF and bOPN expression was intermediate. This module was enriched for genes related to cell adhesion and motility, cytoskeletal remodeling, wingless and integration site signaling, and neuronal development. Most of these canonical pathways centered on integrins, which are receptors for OPN.

CONCLUSIONS

The intestinal transcriptome of breastfed and FF monkeys differs, but bovine OPN at levels similar to human milk shifts gene expression profiles to be more similar to breastfed monkeys.

Tenascin-C aggravates autoimmune myocarditis via dendritic cell activation and Th17 cell differentiation

Background

Tenascin‐C (TN‐C), an extracellular matrix glycoprotein, appears at several important steps of cardiac development in the embryo, but is sparse in the normal adult heart. TN‐C re‐expresses under pathological conditions including myocarditis, and is closely associated with tissue injury and inflammation in both experimental and clinical settings. However, the pathophysiological role of TN‐C in the development of myocarditis is not clear. We examined how TN‐C affects the initiation of experimental autoimmune myocarditis, immunologically.

Methods and Results

A model of experimental autoimmune myocarditis was established in BALB/c mice by immunization with murine α‐myosin heavy chains. We found that TN‐C knockout mice were protected from severe myocarditis compared to wild‐type mice. TN‐C induced synthesis of proinflammatory cytokines, including interleukin (IL)‐6, in dendritic cells via activation of a Toll‐like receptor 4, which led to T‐helper (Th)17 cell differentiation and exacerbated the myocardial inflammation. In the transfer experiment, dendritic cells loaded with cardiac myosin peptide acquired the functional capacity to induce myocarditis when stimulated with TN‐C; however, TN‐C‐stimulated dendritic cells generated from Toll‐like receptor 4 knockout mice did not induce myocarditis in recipients.

Conclusions

Our results demonstrated that TN‐C aggravates autoimmune myocarditis by driving the dendritic cell activation and Th17 differentiation via Toll‐like receptor 4. The blockade of Toll‐like receptor 4‐mediated signaling to inhibit the proinflammatory effects of TN‐C could be a promising therapeutic strategy against autoimmune myocarditis.