Glutathione Metabolism Is a Regulator of the Acute Inflammatory Response of Monocytes to (1→3)-ß-D-Glucan.

(1→3)-ß-D-Glucan (BDG) represents a potent pathogen-associated molecular pattern (PAMP) in triggering the host response to fungal and some bacterial infections. Monocytes play a key role in recognizing BDG and governing the acute host response to infections. However, the mechanisms regulating monocyte's acute response to BDG are poorly understood. We sought to investigate the response of monocytes to BDG at the epigenetic, transcriptomic, and molecular levels. Response of human monocytes to 1, 4, and 24 hours of BDG exposure was investigated using RNA-seq, ATAC-seq, H3K27ac and H3K4me1 ChIP-seq. We show that pathways including glutathione metabolism, pentose phosphate pathway, and citric acid cycle were upregulated at the epigenetic and transcriptomic levels in response to BDG exposure. Strikingly, unlike bacterial lipopolysaccharides, BDG induced intracellular glutathione synthesis. BDG exposure also induced NADP synthesis, increased NADPH/NADP ratio, and increased expression of genes involved in the pentose phosphate pathway in a GSH-dependent manner. By inhibiting GSH synthesis with L-buthionine sulfoximine (BSO) before BDG exposure we show that the GSH pathway promotes cell survival and regulates monocyte's effector functions including NO production, phagocytosis, and cytokine production. In summary, our work demonstrates that BDG induces glutathione synthesis and metabolism in monocytes, which is a major promoter of the acute functional response of monocytes to infections.

Development and application of novel immunoassays for eosinophil granule major basic proteins to evaluate eosinophilia and myeloproliferative disorders.

BACKGROUND: During eosinophil differentiation, the granule eosinophil major basic protein 1 (eMBP1) is synthesized as a 32-kDa precursor form, referred to as proMBP1, which is processed into the 14-kDa mature form of eMBP1. The prevalence of these two forms of MBP1 in most pathological conditions remains unknown. OBJECTIVE: To develop the immunoassays that differentiate mature eMBP1 and proMBP1 and apply them to analyze their levels in biological fluids from patients with eosinophilia and hematologic disorders. METHODS: We produced a series of monoclonal antibodies and selected pairs capable of discriminating between the two molecular forms of eMBP1. Radioimmunoassay (RIA) was performed to simultaneously quantitate the levels of mature eMBP1 and proMBP1 in secretions from patients with chronic rhinosinusitis (CRS) and sera from patients with hypereosinophilic syndrome (HES) and other myeloproliferative disorders. RESULTS: The novel immunoassays possessed less than 1% crossreactivity between mature eMBP1 and proMBP1. Mature eMBP1, but not proMBP1, was found in nasal secretions of CRS patients. In contrast, elevated serum levels of mature eMBP1 and proMBP1 were observed in approximately 60% and 90% of HES patients, respectively, with proMBP1 present in greater quantities than mature eMBP1. Patients with several myeloproliferative disorders also showed high serum levels of proMBP1 while mature eMBP1 remained at basal levels. CONCLUSION: The novel immunoassays successfully differentiated mature eMBP1 and proMBP1 in human biological fluids. Further studies addressing the clinical correlates of these assays will help to develop biomarkers to diagnose and monitor patients with eosinophilia and myeloproliferative disorders.

Isolation, identification, and characterization of the human airway ligand for the eosinophil and mast cell immunoinhibitory receptor Siglec-8.

BACKGROUND: The immunoinhibitory receptor Siglec-8 on the surface of human eosinophils and mast cells binds to sialic acid-containing ligands in the local milieu, resulting in eosinophil apoptosis, inhibition of mast cell degranulation, and suppression of inflammation. Siglec-8 ligands were found on postmortem human trachea and bronchi and on upper airways in 2 compartments, cartilage and submucosal glands, but they were surprisingly absent from the epithelium. We hypothesized that Siglec-8 ligands in submucosal glands and ducts are normally transported to the airway mucus layer, which is lost during tissue preparation. OBJECTIVE: Our aim was to identify the major Siglec-8 sialoglycan ligand on the mucus layer of human airways. METHODS: Human upper airway mucus layer proteins were recovered during presurgical nasal lavage of patients at a sinus clinic. Proteins were resolved by gel electrophoresis and blotted, and Siglec-8 ligands detected. Ligands were purified by size exclusion and affinity chromatography, identified by proteomic mass spectrometry, and validated by electrophoretic and histochemical colocalization. The affinity of Siglec-8 binding to purified human airway ligand was determined by inhibition of glycan binding. RESULTS: A Siglec-8-ligand with a molecular weight of approximately 1000 kDa was found in all patient nasal lavage samples. Purification and identification revealed deleted in malignant brain tumors 1 (DMBT1) (also known by the aliases GP340 and SALSA), a large glycoprotein with multiple O-glycosylation repeats. Immunoblotting, immunohistochemistry, and enzyme treatments confirmed that Siglec-8 ligand on the human airway mucus layer is an isoform of DMBT1 carrying O-linked sialylated keratan sulfate chains (DMBT1S8). Quantitative inhibition revealed that DMBT1S8 has picomolar affinity for Siglec-8. CONCLUSION: A distinct DMBT1 isoform, DMBT1S8, is the major high-avidity ligand for Siglec-8 on human airways.

Functional Cellular Anti-Tumor Mechanisms are Augmented by Genetic Proteoglycan Targeting.

While recent research points to the importance of glycans in cancer immunity, knowledge on functional mechanisms is lacking. In lung carcinoma among other tumors, anti-tumor immunity is suppressed; and while some recent therapies boost T-cell mediated immunity by targeting immune-checkpoint pathways, robust responses are uncommon. Augmenting tumor antigen-specific immune responses by endogenous dendritic cells (DCs) is appealing from a specificity standpoint, but challenging. Here, we show that restricting a heparan sulfate (HS) loss-of-function mutation in the HS sulfating enzyme Ndst1 to predominantly conventional DCs (Ndst1f/f CD11cCre+ mutation) results in marked inhibition of Lewis lung carcinoma growth along with increased tumor-associated CD8+ T cells. In mice deficient in a major DC HS proteoglycan (syndecan-4), splenic CD8+ T cells showed increased anti-tumor cytotoxic responses relative to controls. Studies examining Ndst1f/f CD11cCre + mutants revealed that mutation was associated with an increase in anti-tumor cytolysis using either splenic CD8+ T cells or tumor-infiltrating (TIL) CD8+ T cells purified ex-vivo, and tested in pooled effector-to-target cytolytic assays against tumor cells from respective animals. On glycan compositional analysis, HS purified from Ndst1f/f CD11cCre + mutant DCs had reduced overall sulfation, including reduced sulfation of a tri-sulfated disaccharide species that was intriguingly abundant on wildtype DC HS. Interestingly, antigen presentation in the context of major histocompatibility complex class-I (MHC-I) was enhanced in mutant DCs, with more striking effects in the setting of HS under-sulfation, pointing to a likely regulatory role by sulfated glycans at the antigen/MHC-I - T-cell interface; and possibly future opportunities to improve antigen-specific T cell responses by immunologic targeting of HS proteoglycans in cancer.

Role of cell surface proteoglycans in cancer immunotherapy.

Over the past few decades, understanding how tumor cells evade the immune system and their communication with their tumor microenvironment, has been the subject of intense investigation, with the aim of developing new cancer immunotherapies. The current therapies against cancer such as monoclonal antibodies against checkpoint inhibitors, adoptive T-cell transfer, cytokines, vaccines, and oncolytic viruses have managed to improve the clinical outcome of the patients. However, in some tumor entities, the response is limited and could benefit from the identification of novel therapeutic targets. It is known that tumor-extracellular matrix interplay and matrix remodeling are necessary for anti-tumor and pro-tumoral immune responses. Proteoglycans are dominant components of the extracellular matrix and are a highly heterogeneous group of proteins characterized by the covalent attachment of a specific linear carbohydrate chain of the glycosaminoglycan type. At cell surfaces, these molecules modulate the expression and activity of cytokines, chemokines, growth factors, adhesion molecules, and function as signaling co-receptors. By these mechanisms, proteoglycans influence the behavior of cancer cells and their microenvironment during the progression of solid tumors and hematopoietic malignancies. In this review, we discuss why cell surface proteoglycans are attractive pharmacological targets in cancer, and we present current and recent developments in cancer immunology and immunotherapy utilizing proteoglycan-targeted strategies.

Mechanism of atopic cataract caused by eosinophil granule major basic protein.

Atopic cataracts develop under the ages of 40 years, after which visual acuity rapidly declines. However, the mechanism underlying the development of atopic cataracts is not yet clear. We focused on the eosinophil granule major basic protein (MBP), which was detected in the aqueous humor of atopic cataracts previously, and which was cytotoxic. Specifically, we investigated its origin in this fluid and its effects on lens epithelial cells (LECs). MBP immunostaining was positive in atopic cataract-derived LECs, but negative in age-related cataract-derived LECs. MBP mRNA was not detected in either type of cataract, but protein was detected in the aqueous humor. Furthermore, the flare values associated with atopic cataracts were higher than those with age-related cataracts. When MBP was purified from eosinophils or recombinant MBP was added to LEC culture medium, cell viability decreased in a concentration-dependent manner, but an MBP antibody neutralized the cytotoxic effect of this protein towards these cells. These results were consistent with the flow of MBP into the aqueous humor from the blood due to a compromised blood-aqueous barrier. Thus, MBP could further penetrate the lens capsule and adhere to LECs, resulting in decreased cell viability and the development of atopic cataracts.

Bispecific Antibody Approach for Improved Melanoma-Selective PD-L1 Immune Checkpoint Blockade.

Reactivation of functionally-impaired anticancer T cells by programmed cell death protein 1 (PD-1) and programmed cell death receptor ligand-1 (PD-L1)-blocking antibodies shows prominent therapeutic benefit in advanced melanoma and patients with non-small cell lung cancer. However, current PD-L1-blocking antibodies lack intrinsic tumor selectivity. Therefore, efficacy may be reduced resulting from on-target and off-tumor binding to PD-L1-expressing normal cells. This may lead to indiscriminate activation of antigen-experienced T cells, including those implicated in autoimmune-related adverse events. To direct PD-L1 blockade to chondroitin sulfate proteoglycan 4 (CSPG4)-expressing cancers and to reactivate anticancer T cells more selectively, we constructed bispecific antibody PD-L1xCSPG4. CSPG4 is an established target antigen that is selectively overexpressed on malignant melanoma and various other difficult-to-treat cancers. PD-L1xCSPG4 showed enhanced capacity for CSPG4-directed blockade of PD-L1 on cancer cells. Importantly, treatment of mixed cultures containing primary patient-derived CSPG4-expressing melanoma cells and autologous tumor-infiltrating lymphocytes with PD-L1xCSPG4 significantly enhanced activation status, IFN-γ production, and cytolytic activity of anticancer T cells. In conclusion, tumor-directed blockade of PD-L1 by PD-L1xCSPG4 may improve efficacy and safety of PD-1/PD-L1 checkpoint blockade for treatment of melanoma and other CSPG4-overexpressing malignancies.

A Trypsin-Sensitive Proteoglycan from the Tapeworm Hymenolepis diminuta Inhibits Murine Neutrophil Chemotaxis in vitro by Suppressing p38 MAP Kinase Activation.

It has emerged that neutrophils can play important roles in the host response following infection with helminth parasites. Mice infected with the tapeworm, Hymenolepis diminuta, are protected from some inflammatory conditions, accompanied by reduced neutrophil tissue infiltration. Thus, the ability of a phosphate-buffered saline-soluble extract of the worm (H. diminuta extract [HdE]) was tested for (1) its ability to activate murine neutrophils (Ca2+ mobilization, reactive oxygen species (ROS) and cytokine production); and (2) affect neutrophil chemotaxis in vitro to the penta-peptide, WKYMVm, the chemokine, KC, and leukotriene B4. HdE was not cytotoxic to neutrophils, elicited a Ca2+ response and ROS, but not, cytokine (KC, interleukin-10, tumour necrosis factor-α) generation. HdE is not a chemotactic stimulus for murine neutrophils. However, a heat- and trypsin-sensitive, acid-insensitive proteoglycan (sensitive to sodium metaperiodate) in the HdE significantly reduced neutrophil chemotaxis towards WKYMVm or KC, but not LTB4. The latter suggested that the HdE interfered with p38 mitogen-activated protein kinase signalling, which is important in WKYMVm chemotaxis. Corroborating this, immunoblotting revealed reduced phosphorylated p38, and the downstream signal heat-shock protein-27, in protein extracts from HdE + WkYMVm treated cells compared to those exposed to the penta-peptide only. We speculate that HdE can be used to modify the outcome of neutrophilic disease and that purification of the bioactive proteoglycan(s) from the extract could be used as a template to design immunomodulatory drugs targeting neutrophils.

Serum endocan levels in patients with stable COPD.

BACKGROUND: Endothelial cell specific molecule-1, also called as endocan, is a dermatan sulfate proteoglycan, which is expressed by endothelial cells in alveolar walls of the lung and kidney. High endocan levels are found associated with endothelial dysfunction and inflammation. We hypothesize that endocan level is also high in COPD due to systemic inflammation and endothelial dysfunction. We aimed to investigate the expression of endocan in patients with stable COPD. MATERIAL AND METHODS: The study included patients with COPD and control subjects. COPD patients were classified according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2017 criteria. Demographics, body mass index, smoking history, and comorbidities were recorded. Endocan levels of COPD patients and controls were compared. RESULTS: Totally, 88 subjects (47 stable COPD patients, 41 controls) were evaluated. Endocan levels were significantly higher in COPD patients than control group (860.1±259.8 vs 647.3±316.9 pg/mL, P=0.001). There was no relationship between GOLD COPD categories and endocan levels. Also endocan levels were similar between COPD patients with or without hypoxemia. CONCLUSION: Serum endocan level was significantly higher in patients with stable COPD. Further studies should be performed to better understand the relationship between endocan and COPD.

212Pb-Labeled Antibody 225.28 Targeted to Chondroitin Sulfate Proteoglycan 4 for Triple-Negative Breast Cancer Therapy in Mouse Models.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis. There is a clinical need for effective, targeted therapy strategies that destroy both differentiated TNBC cells and TNBC cancer initiating cells (CICs), as the latter are implicated in the metastasis and recurrence of TNBC. Chondroitin sulfate proteoglycan 4 (CSPG4) is overexpressed on differentiated tumor cells and CICs obtained from TNBC patient specimens, suggesting that CSPG4 may be a clinically relevant target for the imaging and therapy of TNBC. The purpose of this study was to determine whether α-particle radioimmunotherapy (RIT) targeting TNBC cells using the CSPG4-specific monoclonal antibody (mAb) 225.28 as a carrier was effective at eliminating TNBC tumors in preclinical models. To this end, mAb 225.28 labeled with 212Pb (212Pb-225.28) as a source of α-particles for RIT was used for in vitro Scatchard assays and clonogenic survival assays with human TNBC cells (SUM159 and 2LMP) grown as adherent cells or non-adherent CIC-enriched mammospheres. Immune-deficient mice bearing orthotopic SUM159 or 2LMP xenografts were injected i.v. with the targeted (225.28) or irrelevant isotype-matched control (F3-C25) mAbs, labeled with 99mTc, 125I, or 212Pb for in vivo imaging, biodistribution, or tumor growth inhibition studies. 212Pb-225.28 bound to adherent SUM159 and 2LMP cells and to CICs from SUM159 and 2LMP mammospheres with a mean affinity of 0.5 nM. Nearly ten times more binding sites per cell were present on SUM159 cells and CICs compared with 2LMP cells. 212Pb-225.28 was six to seven times more effective than 212Pb-F3-C25 at inhibiting SUM159 cell and CIC clonogenic survival (p < 0.05). Radiolabeled mAb 225.28 showed significantly higher uptake than radiolabeled mAb F3-C25 in SUM159 and 2LMP xenografts (p < 0.05), and the uptake of 212Pb-225.28 in TNBC xenografts was correlated with target epitope expression. 212Pb-225.28 caused dose-dependent growth inhibition of SUM159 xenografts; 0.30 MBq 212Pb-225.28 was significantly more effective than 0.33 MBq 212Pb-F3-C25 at inhibiting tumor growth (p < 0.01). These results suggest that CSPG4-specific 212Pb-225.28 is a useful reagent for RIT of CSPG4-expressing tumors, including metastatic TNBC.

The use of synthetic peptides for detection of anti-citrullinated protein antibodies in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology. A characteristic feature of RA is the presence of anti-citrullinated protein antibodies (ACPA). Since ACPAs are highly specific for RA and are often present before the onset of RA symptoms, they have become valuable diagnostic and prognostic. As a result, several assays for detection of ACPAs exist, which vary in sensitivity and specificity. In this study, we analyzed the reactivity of RA sera to selected peptides by solid-phase immunoassays in order to develop an ACPA assay with improved sensitivity and specificity. ACPA levels were determined with respect to sensitivity and specificity in 332 serum samples using the newly developed peptide panel, which was compared to the commercial assays CCPlus (Eurodiagnostica) and CCP3.1 (Inova Diagnostics). A primary panel (peptides 814, 33062 and 33156) was identified, which obtained a sensitivity of 71%, while the complete peptide panel reacted with 79% of RA sera screened. Total specificities of 89% and 80% were obtained for the primary peptide panel and the complete peptide panel. Sensitivities for the commercial assays ranged between 71% and 76% and specificities between 88% and 90%. These findings indicate that the generated peptide panel is optimal for ACPA detection and able to compete with commercial available assays. Collectively, this study may contribute to characterize autoimmunity towards citrullinated proteins and to the development of new and improved diagnostic assays for detection of ACPA and determination of RA.

In-vitro characterization of canine multipotent stromal cells isolated from synovium, bone marrow, and adipose tissue: a donor-matched comparative study.

BACKGROUND: The dog represents an excellent large animal model for translational cell-based studies. Importantly, the properties of canine multipotent stromal cells (cMSCs) and the ideal tissue source for specific translational studies have yet to be established. The aim of this study was to characterize cMSCs derived from synovium, bone marrow, and adipose tissue using a donor-matched study design and a comprehensive series of in-vitro characterization, differentiation, and immunomodulation assays. METHODS: Canine MSCs were isolated from five dogs with cranial cruciate ligament rupture. All 15 cMSC preparations were evaluated using colony forming unit (CFU) assays, flow cytometry analysis, RT-PCR for pluripotency-associated genes, proliferation assays, trilineage differentiation assays, and immunomodulation assays. Data were reported as mean ± standard deviation and compared using repeated-measures analysis of variance and Tukey post-hoc test. Significance was established at p < 0.05. RESULTS: All tissue samples produced plastic adherent, spindle-shaped preparations of cMSCs. Cells were negative for CD34, CD45, and STRO-1 and positive for CD9, CD44, and CD90, whereas the degree to which cells were positive for CD105 was variable depending on tissue of origin. Cells were positive for the pluripotency-associated genes NANOG, OCT4, and SOX2. Accounting for donor and tissue sources, there were significant differences in CFU potential, rate of proliferation, trilineage differentiation, and immunomodulatory response. Synovium and marrow cMSCs exhibited superior early osteogenic activity, but when assessing late-stage osteogenesis no significant differences were detected. Interestingly, bone morphogenic protein-2 (BMP-2) supplementation was necessary for early-stage and late-stage osteogenic differentiation, a finding consistent with other canine studies. Additionally, synovium and adipose cMSCs proliferated more rapidly, displayed higher CFU potential, and formed larger aggregates in chondrogenic assays, although proteoglycan and collagen type II staining were subjectively decreased in adipose pellets as compared to synovial and marrow pellets. Lastly, cMSCs derived from all three tissue sources modulated murine macrophage TNF-α and IL-6 levels in a lipopolysaccharide-stimulated coculture assay. CONCLUSIONS: While cMSCs from synovium, marrow, and adipose tissue share a number of similarities, important differences in proliferation and trilineage differentiation exist and should be considered when selecting cMSCs for translational studies. These results and associated methods will prove useful for future translational studies involving the canine model.

Is neuroglial antigen 2 a potential contributor to cilengitide response in glioblastoma?

BACKGROUND: Determining the expression levels of neuroglial antigen 2 (NG2) in glioma cell lines and to evaluate the potential contribution of NG2 to cilengitide response were aimed. MATERIALS AND METHODS: Endogenous expression level of NG2 was determined using quantitative reverse transcription polymerase chain reaction and immunoblotting. Cilengitide responses of the cells were monitored to determine half maximal inhibitory concentration values. Whether the suppression of NG2 expression alters the response of A172 cells to cilengitide was examined. RESULTS: The effect of cilengitide on inducing apoptosis of the cells was determined by TUNEL staining. High mRNA and protein expression of NG2 was detected in A172 and U-87MG cells, while T98G, M059K and M059J cells demonstrated low levels of NG2. A172, U-87MG and positive control MG-63 were relatively sensitive to cilengitide compared to T98G, M059K and M059J. MG-63, A172 and U-87MG were unexpectedly found to be more susceptible to cilengitide. In addition, NG2 knock-down showed no significant difference in cell death between small interfering RNA (siRNA)-transfected and cilengitide-treated groups. The results showed that cilengitide caused detachment and subsequently initiated apoptosis. Glioma cell lines express variable levels of NG2 and differ in their responses to cilengitide. Although increased numbers of apoptotic cells were found in untransfected cells compared to siRNA-transfected cells upon exposed to cilengitide, the difference was not documented to be significant between two groups. CONCLUSION: It may be proposed that the combination therapy of NG2 suppression and cilengitide treatment showed no considerable effect on glioblastoma compared to cilengitide therapy alone. Response to therapy may be further improved by targeting other factors act in concert in this signaling pathway.

Evaluation of Selected Immunomodulatory Glycoproteins as an Adjunct to Cancer Immunotherapy.

Polysaccharopeptide (PSP), from Coriolus versicolor, has been used widely as an adjuvant to chemotherapy with demonstrated anti-tumor and broad immunomodulating effects. While PSP's mechanism of action still remains unknown, its enhanced immunomodulatory potential with acacia gum is of great interest. Acacia gum, which also contains polysaccharides and glycoproteins, has been demonstrated to be immunopotentiating. To elucidate whether PSP directly activates T-cell-dependent B-cell responses in vivo, we used a well-established hapten carrier system (Nitrophenyl-chicken gamma globulin (NP-CGG)). 6-week C57BL/6 male mice were immunised with 50 µg of NP25-CGG alum precipitate intraperitoneally. Mice were gavaged daily with 50 mg/kg PSP in a vehicle containing acacia gum and sacrificed at days 0, 4, 7, 10, 14 and 21. ELISA was used to measure the total and relative hapten-specific anti-NP IgA, IgM and IgG titre levels compared to the controls. It was found that PSP, combined with acacia gum, significantly increased total IgG titre levels at day 4 (P< 0.05), decreased IgM titre levels at days 4 and 21 (P< 0.05) with no alterations observed in the IgA or IgE titre levels at any of the time points measured. Our results suggest that while PSP combined with acacia gum appears to exert weak immunological effects through specific T-cell dependent B-cell responses, they are likely to be broad and non-specific which supports the current literature on PSP. We report for the first time the application of a well-established hapten-carrier system that can be used to characterise and delineate specific T-cell dependent B-cell responses of potential immunomodulatory glycoprotein-based herbal medicines combinations in vivo.

Decoding the Matrix: Instructive Roles of Proteoglycan Receptors.

The extracellular matrix is a dynamic repository harboring instructive cues that embody substantial regulatory dominance over many evolutionarily conserved intracellular activities, including proliferation, apoptosis, migration, motility, and autophagy. The matrix also coordinates and parses hierarchical information, such as angiogenesis, tumorigenesis, and immunological responses, typically providing the critical determinants driving each outcome. We provide the first comprehensive review focused on proteoglycan receptors, that is, signaling transmembrane proteins that use secreted proteoglycans as ligands, in addition to their natural ligands. The majority of these receptors belong to an exclusive subset of receptor tyrosine kinases and assorted cell surface receptors that specifically bind, transduce, and modulate fundamental cellular processes following interactions with proteoglycans. The class of small leucine-rich proteoglycans is the most studied so far and constitutes the best understood example of proteoglycan-receptor interactions. Decorin and biglycan evoke autophagy and immunological responses that deter, suppress, or exacerbate pathological conditions such as tumorigenesis, angiogenesis, and chronic inflammatory disease. Basement membrane-associated heparan sulfate proteoglycans (perlecan, agrin, and collagen XVIII) represent a unique cohort and provide proteolytically cleaved bioactive fragments for modulating cellular behavior. The receptors that bind the genuinely multifactorial and multivalent proteoglycans represent a nexus in understanding basic biological pathways and open new avenues for therapeutic and pharmacological intervention.

Chondroitin sulfate proteoglycan 4 as a target for chimeric antigen receptor-based T-cell immunotherapy of solid tumors.

INTRODUCTION: Proteoglycans are critical molecules involved in multiple physiological cell functions, but also key players in cancer development and progression. In particular, chondroitin sulfate proteoglycan 4 (CSPG4) is recognized as an attractive target for antibody-based approaches because of its high expression on cancer cells in several types of human malignancies and its restricted distribution in normal tissues. AREAS COVERED: Adoptive transfer of genetically modified T cells is emerging as a powerful therapeutic approach in cancer patients. In this regard, the selection of the appropriate antigen to be targeted in solid tumors becomes a critical aspect in promoting potent antitumor effects while preventing toxicities. This review summarizes the authors' current knowledge on the expression and function of CSPG4 in normal tissues and malignant tumors, with a particular focus on the potential use of CSPG4 as a target for antigen-specificity redirected T cells. EXPERT OPINION: T cells expressing a CSPG4-specific chimeric antigen receptor (CAR) offer the possibility to target a broad spectrum of solid tumors for which no curative treatment is currently available. In addition, since CSPG4 is also selectively up-regulated on tumor-associated pericytes, targeting this antigen may also contribute to tumor regression via inhibition of neoangiogenesis. Preclinical experiments to date justify the clinical translation of CSPG4-specific CAR-T cells.

A Novel In-Frame Deletion in the Leucine Zipper Domain of C/EBPε Leads to Neutrophil-Specific Granule Deficiency.

Neutrophil-specific granule deficiency (SGD) is a rare autosomal recessive primary immunodeficiency characterized by neutrophil dysfunction, bilobed neutrophil nuclei and lack of neutrophil-specific granules. Defects in a myeloid-specific transcription factor, CCAAT/enhancer binding protein-ε (C/EBPε), have been identified in two cases in which homozygous frameshift mutations led to loss of the leucine zipper domain. In this study, we report a 55-y-old woman affected with SGD caused by a novel homozygous 2-aa deletion (ΔRS) in the leucine zipper domain of the C/EBPε gene. The patient showed characteristic neutrophil abnormalities and recurrent skin infections; however, there was no history of deep organ infections. Biochemical analysis revealed that, in contrast to the two frameshift mutations, the ΔRS mutant maintained normal cellular localization, DNA-binding activity, and dimerization, and all three mutants exhibited marked reduction in transcriptional activity. The ΔRS mutant was defective in its association with Gata1 and PU.1, as well as aberrant cooperative transcriptional activation of eosinophil major basic protein. Thus, the ΔRS likely impairs protein-protein interaction with other transcription factors, resulting in a loss of transcriptional activation. These results further support the importance of the leucine zipper domain of C/EBPε for its essential function, and indicate that multiple molecular mechanisms lead to SGD.

Dual targeting NG2 and GD3A using Mab-Zap immunotoxin results in reduced glioma cell viability in vitro.

BACKGROUND: Effective treatments for glioblastoma multiforme (GBM) are lacking due, in part, to cellular heterogeneity. Consequently, single-target therapeutic strategies are unlikely to succeed. Simultaneous targeting of different neoplastic cell populations within the same tumour may, therefore, prove of value. Neuron-glia 2 (NG2), a transmembrane chondroitin sulphate proteoglycan, present on developing glial cells, and GD3(A), a ganglioside expressed on developing migratory glia, are re-expressed in GBM. MATERIALS AND METHODS: The aims of this study were to conduct 'proof of concept' experiments in human GBM cell lines to show that proliferative high NG2-expressing cells and high GD3(A) -expressing migratory cells could be effectively ablated using a Mab-Zap saporin immunotoxin system. RESULTS: The combinatorial ablation of both NG2 and GD3(A)-expressing cells resulted in significant reduction in GBM cell viability compared to single epitope targeting and controls (p<0.0001); non-neoplastic astrocytes were not affected. CONCLUSION: Multiple targeting of GBM sub-populations may, therefore, help inform novel therapeutic approaches.

Mesenchymal stem cell therapy in proteoglycan induced arthritis.

OBJECTIVES: To explore the immunosuppressive effect and mechanism of action of intraperitoneal (ip) and intra-articular (ia) mesenchymal stem cell (MSC) injection in proteoglycan induced arthritis (PGIA). METHODS: MSC were administered ip or ia after establishment of arthritis. We used serial bioluminescence imaging (BLI) to trace luciferase-transfected MSC. Mice were sacrificed at different time points to examine immunomodulatory changes in blood and secondary lymphoid organs. RESULTS: Both ip and local ia MSC injection resulted in a beneficial clinical and histological effect on established PGIA. BLI showed that MSC ip and ia in arthritic mice are largely retained for several weeks in the peritoneal cavity or injected joint respectively, without signs of migration. Following MSC treatment pathogenic PG-specific IgG2a antibodies in serum decreased. The Th2 cytokine IL-4 was only upregulated in PG-stimulated lymphocytes from spleens in ip treated mice and in lymphocytes from draining lymph nodes in ia treated mice. An increase in production of IL-10 was seen with equal distribution. Although IFN-γ was also elevated, the IFN-γ/IL-4 ratio in MSC treated mice was opposite to the ratio in (untreated) active PGIA. CONCLUSIONS: MSC treatment, both ip and ia, suppresses PGIA, a non-collagen induced arthritis model. MSC are largely retained for weeks in the injection region. MSC treatment induced at the region of injection a deviation of PG-specific immune responses, suggesting a more regulatory phenotype with production of IL-4 and IL-10, but also of IFN-γ, and a systemic decrease of pathogenic PG-specific IgG2a antibodies. These findings underpin the potential of MSC treatment in resistant arthritis.

Dynamic contrast enhanced MRI detects early response to adoptive NK cellular immunotherapy targeting the NG2 proteoglycan in a rat model of glioblastoma.

There are currently no established radiological parameters that predict response to immunotherapy. We hypothesised that multiparametric, longitudinal magnetic resonance imaging (MRI) of physiological parameters and pharmacokinetic models might detect early biological responses to immunotherapy for glioblastoma targeting NG2/CSPG4 with mAb9.2.27 combined with natural killer (NK) cells. Contrast enhanced conventional T1-weighted MRI at 7±1 and 17±2 days post-treatment failed to detect differences in tumour size between the treatment groups, whereas, follow-up scans at 3 months demonstrated diminished signal intensity and tumour volume in the surviving NK+mAb9.2.27 treated animals. Notably, interstitial volume fraction (ve), was significantly increased in the NK+mAb9.2.27 combination therapy group compared mAb9.2.27 and NK cell monotherapy groups (p = 0.002 and p = 0.017 respectively) in cohort 1 animals treated with 1 million NK cells. ve was reproducibly increased in the combination NK+mAb9.2.27 compared to NK cell monotherapy in cohort 2 treated with increased dose of 2 million NK cells (p<0.0001), indicating greater cell death induced by NK+mAb9.2.27 treatment. The interstitial volume fraction in the NK monotherapy group was significantly reduced compared to mAb9.2.27 monotherapy (p<0.0001) and untreated controls (p = 0.014) in the cohort 2 animals. NK cells in monotherapy were unable to kill the U87MG cells that highly expressed class I human leucocyte antigens, and diminished stress ligands for activating receptors. A significant association between apparent diffusion coefficient (ADC) of water and ve in combination NK+mAb9.2.27 and NK monotherapy treated tumours was evident, where increased ADC corresponded to reduced ve in both cases. Collectively, these data support histological measures at end-stage demonstrating diminished tumour cell proliferation and pronounced apoptosis in the NK+mAb9.2.27 treated tumours compared to the other groups. In conclusion, ve was the most reliable radiological parameter for detecting response to intralesional NK cellular therapy.