Engineering superactive granulocyte macrophage colony‐stimulating factor transferrin fusion proteins as orally‐delivered candidate agents for treating neurodegenerative disease

Intravenously injected granulocyte macrophage colony‐stimulating factor (GM‐CSF) has shown efficacy in Alzheimer's Disease (AD) and Parkinson's Disease (PD) animal studies and is undergoing clinical evaluation. The likely need for dosing of GM‐CSF to patients over months or years motivates pursuit of avenues for delivering GM‐CSF to circulation via oral administration. Flow cytometric screening of 37 yeast‐displayed GM‐CSF saturation mutant libraries revealed residues P12, H15, R23, R24, and K72 as key determinants of GM‐CSF's CD116 and CD131 GM‐CSF receptor (GM‐CSFR) subunit binding affinity. Screening combinatorial GM‐CSF libraries mutated at positions P12, H15, and R23 yielded variants with increased affinities toward both CD116 and CD131. Genetic fusion of GM‐CSF to human transferrin (Trf), a strategy that enables oral delivery of other biopharmaceuticals in animals, yielded bioactive wild type and variant cytokines upon secretion from cultured Human Embryonic Kidney cells. Surface plasmon resonance (SPR) measurements showed that all evaluated variants possess decreases in CD116 and CD131 binding K_D values of up to 2.5‐fold relative to wild type. Improved affinity led to increased in vitro bioactivity; the most bioactive variant, P12D/H15L/R23L, had a leukocyte proliferation assay EC₅₀ value 3.5‐fold lower than the wild type GM‐CSF/Trf fusion. These outcomes are important first steps toward our goal of developing GM‐CSF/Trf fusions as orally available AD and PD therapeutics. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:668–677, 2015     

Mesenchymal stem cells are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction

Summary Both cell therapy and angiogenic growth factor gene therapy have been applied to animal studies and clinical trials. Little is known about the direct comparison between cell therapy and angiogenic growth factor gene therapy. The goal of this study was to compare the effects of human bone marrow-derived mesenchymal stem cells (hMSCs) transplantation and injection of angiogenic growth factor genes in a model of acute myocardial infarction in mice. The hMSCs were obtained from adult human bone marrow and expanded in vitro. The purity and characteristics of hMSCs were identified by flow cytometry and immunophenotyping. Immediately after ligation of the left anterior descending coronary artery in male severe combined immunodeficient (SCID) mice, culture-expanded hMSCs or angiogenic growth factor genes were injected intramuscularly at the left anterior free wall. The engrafted hMSCs were positive for cardiac marker, desmin. Infarct size was significantly smaller in the hMSCs-treated group than in the angiopoietin-1 (Ang-1) or vascular endothelial growth factor (VEGF)-treated group at day 28 after infarction. hMSCs transplantation was better in decreasing left ventricular end-diastolic dimension and increasing fractional shortening than Ang1 or VEGF gene therapy. Capillary density was markedly increased after hMSCs transplantation than Ang1 and VEGF gene therapy. In conclusion, intramyocardial transplantation of hMSCs improves cardiac function after acute myocardial infarction through enhancement of angiogenesis and myogenesis in the ischemic myocardium. hMSCs are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction. Transplantation of MSCs may become the future therapy for acute myocardial infarction for myocardial regeneration.     

Granulocyte‐macrophage colony‐stimulating factor antibody suppresses microglial activity: implications for anti‐inflammatory effects in Alzheimer’s Disease and multiple sclerosis

The objective of our study was to determine granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) activity in the brain following GM‐CSF induction. We injected recombinant mouse GM‐CSF into the brains of 8‐month‐old C57BL6 mice via intracerebroventricular injections and studied the activities of microglia, astrocytes, and neurons. We also sought to determine whether an anti‐GM‐CSF antibody could suppress endogenous microglial activity in the C57BL6 mice and could also suppress microglial activity induced by the recombinant mouse GM‐CSF in another group of C57BL6 mice. Using quantitative real‐time RT‐PCR, we assessed microglial, astrocytic, and neuronal activity by measuring mRNA expression of pro‐inflammatory cytokines, GFAP, and the neuronal marker NeuN in the cerebral cortex tissues from C57BL6 mice. We performed immunoblotting and immunohistochemistry of activated microglia in different regions of the brains from control (phosphate‐buffered saline‐injected C57BL6 mice) and experimental mice (recombinant GM‐CSF‐injected C57BL6 mice, GM‐CSF antibody‐injected C57BL6 mice, and recombinant mouse GM‐CSF plus anti‐GM‐CSF antibody‐injected C57BL6 mice). We found increased mRNA expression of CD40 (9.75‐fold), tumor necrosis factor‐alpha (2.1‐fold), CD45 (1.73‐fold), and CD11c (1.70‐fold) in the cerebral cortex of C57BL6 mice that were induced with recombinant GM‐CSF, compared with control mice. Further, the anti‐GM‐CSF antibody suppressed microglia in mice that were induced with recombinant GM‐CSF. Our immunoblotting and immunohistochemistry findings of GM‐CSF‐associated cytokines in C57BL6 mice induced with recombinant GM‐CSF, in C57BL6 mice injected with the anti‐GM‐CSF antibody, and in C57BL6 mice injected with recombinant mouse GM‐CSF plus anti‐GM‐CSF antibody concurred with our real‐time RT‐PCR findings. These findings suggest that GM‐CSF is critical for microglial activation and that anti‐GM‐CSF antibody suppresses microglial activity in the CNS. The findings from this study may have implications for anti‐inflammatory effects of Alzheimer’s disease and experimental autoimmune encephalomyelitis mice (a multiple sclerosis mouse model).     

Protective immunity against Bordetella pertussis by a recombinant DNA vaccine and the effect of coinjection with a granulocyte-macrophage colony stimulating factor gene

A recombinant pertussis DNA vaccine was described here with its immunogenicity and the ability to induce protection against B. pertussis infection in mice. Three immunodominant antigen gene fragments of pertussis, pertussis toxin subunit 1 (pts1), fragments of pertactin (prn) and filamentous hemagglutinin (fha), were recombined as fragment pts1-prn-fha named ppf, and it was cloned to plasmid pVAX1 as pVAX1/ppf. Compared to those injected with pVAX1, the mice injected with pVAX1/ppf significantly elicited more antigen specific antibody anti-PTS1, anti-PRN, anti-FHA and cytokine IL-10, IFN-gamma. When pGM-CSF was coinjected with pVAX1/ppf, the mice showed significantly increases of the three antibodies and cytokine IL-10, IL-4, IFN-gamma and TNF-alpha compared to those injected with pVAX1 only. The mice in group pVAX1/ppf & pGM-CSF, in particular; induced much more anti-PTS1, IL-4 and TNF-alpha than those in group pVAX1/ppf. In the intracerebral mouse protection test, the mice immunized with pVAX1/ppf or pVAX1/ppf & pGM-CSF induced protection to a lethal dose of B. pertussis. The results indicate that recombinant DNA vaccine and pGM-CSF coinjection can induce protective immunity against B. pertussis, demonstrating a valuable method to prevent pertussis.     

Receptor activator of nuclear factor‐kappa B ligand induces osteoclast formation in RAW 264.7 macrophage cells via augmented production of macrophage–colony‐stimulating factor

RAW 264.7 macrophage cells differentiate into osteoclast‐like cells in the presence of RANKL. Participation of M‐CSF in RANKL‐induced osteoclast formation of RAW 264.7 cells was examined. TRAP‐positive osteoclast‐like cells appeared in RAW 264.7 cells cultured in the presence of RANKL. RANKL‐induced osteoclast formation was markedly inhibited by anti‐M‐CSF antibody. RANKL augmented M‐CSF mRNA expression and M‐CSF production in RAW 264.7 cells. Further, anti‐M‐CSF antibody inhibited the expression of RANK, c‐fms, c‐fos and TRAP mRNA in RANKL‐stimulated RAW 264.7 cells. However, anti‐M‐CSF antibody did not affect the expression of DC‐STAMP in the stimulated cells. Therefore, RANKL was suggested to induce osteoclast formation in RAW 264.7 cells via augmented production of M‐CSF. The putative role of M‐CSF in RANKL‐induced osteoclast formation of RAW 264.7 cells is discussed.     

Neuroprotective effects of granulocyte-colony stimulating factor in a novel transgenic mouse model of SCA17

Spinocerebellar ataxia type 17 (SCA17) is an autosomal dominant inherited disorder characterized by degeneration of spinocerebellar tracts and selected brainstem neurons owing to the expansion of a CAG repeat of the human TATA-binding protein (hTBP) gene. To gain insight into the pathogenesis of this hTBP mutation, we generated transgenic mice with the mutant hTBP gene driven by the Purkinje specific protein (Pcp2/L7) gene promoter. Mice with the expanded hTBP allele developed ataxia within 2-5 months. Behavioral analysis of L7-hTBP transgenic mice showed reduced fall latency in a rotarod assay. Purkinje cell degeneration was identified by immunostaining of calbindin and IP3R1. Reactive gliosis and neuroinflammation occurred in the transgenic cerebellum, accompanied by up-regulation of GFAP and Iba1. The L7-hTBP transgenic mice were thus confirmed to recapitulate the SCA17 phenotype and were used as a disease model to explore the potential of granulocyte-colony stimulating factor in SCA17 treatment. Our results suggest that granulocyte-colony stimulating factor has a neuroprotective effect in these transgenic mice, ameliorating their neurological and behavioral deficits. These data indicate that the expression of the mutant hTBP in Purkinje cells is sufficient to produce cell degeneration and an ataxia phenotype, and constitutes a good model for better analysis of the neurodegeneration in SCA17.     

Effects of PEMF on microcirculation and angiogenesis in a model of acute hindlimb ischemia in diabetic rats

Hindlimb ischemia is a major complication of diabetic patients due to poor neovascularization. Therapy with pulsed electromagnetic fields (PEMF) can promote angiogenesis in ischemic lesions. However, the efficacy and therapeutic mechanisms of PEMF in diabetes‐related hindlimb ischemia are unclear. Sprague–Dawley rats were injected with streptozocin to induce diabetes, and 10 weeks later diabetic rats were subjected to surgical induction of acute hindlimb ischemia. The rats were randomized and treated with PEMF, and the blood perfusion of individual rats was determined longitudinally by laser Doppler perfusion imaging (LDPI). The neovascular density was examined using immunofluorescent analysis of CD31 expression and alkaline phosphatase (AP) staining. The levels of VEGF, VEGFR, FGF‐2, and FGFR1 expression, and ERK 1/2 and P38 phosphorylation in the muscles were characterized using enzyme‐linked immunosorbent assay (ELISA) and Western blot assays. The values of LDPI in the PEMF‐treated rats at 14 and 28 days post surgery were significantly greater than those in the controls, accompanied by significantly elevated levels of anti‐CD31 and AP staining. The relative levels of FGF‐2 and FGFR1, but not VEGF and VEGFR expression, and ERK1/2, but not P38 phosphorylation, in the muscles of the PEMF‐treated rats were significantly higher than those in the controls. Our data indicated that PEMF enhanced acute hindlimb ischemia‐related perfusion and angiogenesis, associated with up‐regulating FGF‐2 expression and activating the ERK1/2 pathway in diabetic rats. Therefore, PEMF may be valuable for the treatment of diabetic patients with ischemic injury. Bioelectromagnetics 34:180–188, 2013. © 2012 Wiley Periodicals, Inc.     

FACS-purified myoblasts producing controlled VEGF levels induce safe and stable angiogenesis in chronic hind limb ischemia

We recently developed a method to control the in vivo distribution of vascular endothelial growth factor (VEGF) by high throughput Fluorescence-Activated Cell Sorting (FACS) purification of transduced progenitors such that they homogeneously express specific VEGF levels. Here we investigated the long-term safety of this method in chronic hind limb ischemia in nude rats. Primary myoblasts were transduced to co-express rat VEGF-A(164) (rVEGF) and truncated ratCD8a, the latter serving as a FACS-quantifiable surface marker. Based on the CD8 fluorescence of a reference clonal population, which expressed the desired VEGF level, cells producing similar VEGF levels were sorted from the primary population, which contained cells with very heterogeneous VEGF levels. One week after ischemia induction, 12 × 10(6) cells were implanted in the thigh muscles. Unsorted myoblasts caused angioma-like structures, whereas purified cells only induced normal capillaries that were stable after 3 months. Vessel density was doubled in engrafted areas, but only approximately 0.1% of muscle volume showed cell engraftment, explaining why no increase in total blood flow was observed. In conclusion, the use of FACS-purified myoblasts granted the cell-by-cell control of VEGF expression levels, which ensured long-term safety in a model of chronic ischemia. Based on these results, the total number of implanted cells required to achieve efficacy will need to be determined before a clinical application.     

Pulsed ultrasound promotes melanoblast migration through upregulation of macrophage colony‐stimulating factor/focal adhesion kinase autocrine signaling and paracrine mechanisms

Repigmentation of vitiliginous lesions relies on the proliferation and migration of melanoblasts from hair follicles to the epidermis. Pulsed ultrasound has been demonstrated to have stimulatory effects on cell proliferation and migration and has been applied clinically to enhance tissue repair. To clarify the biologic effects and signaling mechanisms of pulsed ultrasound on melanoblast proliferation and migration, two melanoblast cell lines, the undifferentiated NCCmelb4 cells and the differentiated NCCmelan5 cells, were examined. We demonstrated that pulsed ultrasound increased cell migration in a dose‐dependent manner without altering cell proliferation. Pulsed ultrasound enhanced autocrine secretion of macrophage colony‐stimulating factor (M‐CSF), which subsequently activated the focal adhesion kinase (FAK) pathway to promote melanoblast migration. Furthermore, conditioned medium from mouse embryonic fibroblasts NIH 3T3 and primary human keratinocytes treated with pulsed ultrasound could stimulate melanoblast migration through a paracrine effect. Our results provide a novel mechanism to promote migration of melanoblasts by pulsed ultrasound stimulation.     

Effect of the in vivo application of granulocyte colony‐stimulating factor on NK cells in bone marrow and peripheral blood

Granulocyte colony‐stimulating factor (G‐CSF) has been widely used in the field of allogeneic haematopoietic stem cell transplantation (allo‐HSCT) for priming donor stem cells from the bone marrow (BM) to peripheral blood (PB) to collect stem cells more conveniently. Donor‐derived natural killer (NK) cells have important antitumour functions and immune regulatory roles post‐allo‐HSCT. The aim of this study was to evaluate the effect of G‐CSF on donors' NK cells in BM and PB. The percentage of NK cells among nuclear cells and lymphocyte was significantly decreased and led to increased ratio of T and NK cells in BM and PB post‐G‐CSF in vivo application. Relative expansion of CD56^bri NK cells led to a decreased ratio of CD56^dim and CD56^bri NK subsets in BM and PB post‐G‐CSF in vivo application. The expression of CD62L, CD54, CD94, NKP30 and CXCR4 on NK cells was significantly increased in PB after G‐CSF treatment. G‐CSF treatment decreased the IFN‐γ‐secreting NK population (NK1) dramatically in BM and PB, but increased the IL‐13‐secreting NK (NK2), TGF‐β‐secreting NK (NK3) and IL‐10‐secreting NK (NKr) populations significantly in BM. Clinical data demonstrated that higher doses of NK1 infused into the allograft correlated with an increased incidence of chronic graft‐vs‐host disease post‐transplantation. Taken together, our results show that the in vivo application of G‐CSF can modulate NK subpopulations, leading to an increased ratio of T and NK cells and decreased ratio of CD56^dim and CD56^bri NK cells as well as decreased NK1 populations in both PB and BM.     

Treatment of chronical myocardial ischemia by adenovirus-mediated hepatocyte growth factor gene transfer in minipigs

Growth factor gene transfer-induced therapeutic angiogenesis has become a novel approach for the treatment of myocardial ischemia. In order to provide a basis for the clinical application of an adeno- virus with hepatocyte growth factor gene (Ad-HGF) in the treatment of myocardial ischemia, we estab- lished a minipig model of chronically ischemic myocardium in which an Ameroid constrictor was placed around the left circumflex branch of the coronary artery (LCX). A total of 18 minipigs were ran- domly divided into 3 groups: a surgery control group, a model group and an Ad-HGF treatment group implanted with Ameroid constrictor. Ad-HGF or the control agent was injected directly into the ischemic myocardium, and an improvement in heart function and blood supply were evaluated. The results showed that myocardial perfusion remarkably improved in the Ad-HGF group compared with that in both the control and model groups. Four weeks after the treatment, the density of newly formed blood vessels was higher and the number of collateral blood vessels was greater in the Ad-HGF group than in the model group. The area of myocardial ischemia reduced evidently and the left ventricular ejection fraction improved significantly in the Ad-HGF group. These results suggest that HGF gene therapy may become a novel approach in the treatment of chronically ischemic myocardium.     

The mechanism for the radioprotective effects of zymosan‐A in mice

It proved that Zymosan‐A protected the haematopoietic system from radiation‐induced damage via Toll‐Like Receptor2 in our previous study. In this study, we investigated the potential mechanism for the radioprotective effects of Zymosan‐A. The mice were treated with Zymosan‐A (50 mg/kg, dissolved in NS) via peritoneal injection 24 and 2 hours before ionizing radiation. Apoptosis of bone marrow cells and the levels of IL‐6, IL‐12, G‐CSF and GM‐CSF were evaluated by flow cytometry assay. DNA damage was determined by γ‐H2AX foci assay. In addition, RNA sequencing was performed to identify differentially expressed genes (DEGs). Zymosan‐A protected bone marrow cells from radiation‐induced apoptosis, up‐regulated IL‐6, IL‐12, G‐CSF and GM‐CSF in bone marrow cells. Zymosan‐A also protected cells from radiation‐induced DNA damage. Moreover, RNA sequencing analysis revealed that Zymosan‐A induced 131 DEGs involved in the regulation of immune system process and inflammatory response. The DEGs were mainly clustered in 18 KEGG pathways which were also associated with immune system processes. Zymosan‐A protected bone marrow cells from radiation‐induced apoptosis and up‐regulated IL‐6, IL‐12, G‐CSF and GM‐CSF. Moreover, Zymosan‐A might also exhibit radioprotective effects through regulating immune system process and inflammatory response. These results provided new knowledge regarding the radioprotective effect of Zymosan‐A.     

An inducible mouse model for epidermolysis bullosa simplex: implications for gene therapy

The Dowling-Meara variant of epidermolysis bullosa simplex (EBS-DM) is a severe blistering disease inherited in an autosomal-dominant fashion. Here we report the generation of a mouse model that allows focal activation of a mutant keratin 14 allele in epidermal stem cells upon topical administration of an inducer, resulting in EBS phenotypes in treated areas. Using laser capture microdissection, we show that induced blisters healed by migration of surrounding nonphenotypic stem cells into the wound bed. This observation provides an explanation for the lack of mosaic forms of EBS-DM. In addition, we show that decreased mutant keratin 14 expression resulted in normal morphology and functions of the skin. Our results have important implications for gene therapy of EBS and other dominantly inherited diseases.     

Aquaporin‐1 inhibition reduces metastatic formation in a mouse model of melanoma

Aquaporin‐1 (AQP1) is a proangiogenic water channel protein promoting endothelial cell migration. We previously reported that AQP1 silencing by RNA interference reduces angiogenesis‐dependent primary tumour growth in a mouse model of melanoma. In this study, we tested the hypothesis that AQP1 inhibition also affects animal survival and lung nodule formation. Melanoma was induced by injecting B16F10 cells into the back of C57BL6J mice. Intratumoural injection of AQP1 siRNA and CTRL siRNA was performed 10 days after tumour cell implantation. Lung nodule formation was analysed after the death of the mice. Western blot was used to quantify HIF‐1α, caspase‐3 (CASP3) and metalloproteinase‐2 (MMP2) protein levels. We found that AQP1 knock‐down (KD) strongly inhibited metastatic lung nodule formation. Moreover, AQP1 siRNA‐treated mice showed a twofold survival advantage compared to mice receiving CTRL siRNAs. The reduced AQP1‐dependent tumour angiogenesis caused a hypoxic condition, evaluated by HIF‐1α significant increase, in turn causing an increased level of apoptosis in AQP1 KD tumours, assessed by CASP3 quantification and DNA fragmentation. Importantly, a decreased level of MMP2 after AQP1 KD indicated a decreased activity against extracellular matrix associated with reduced vascularization and metastatic formation. In conclusion, these findings highlight an additional role for AQP1 as an important determinant of tumour dissemination by facilitating tumour cell extravasation and metastatic formation. This study adds knowledge on the role played by AQP1 in tumour biology and supports the view of AQP1 as a potential drug target for cancer therapy.