A novel rationally designed agonist antibody fragment that functionally mimics thrombopoietin

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 2541-2541
Author(s):  
M. Renshaw ◽  
S. Frederickson ◽  
B. Lin ◽  
X. Su ◽  
Y. Wang ◽  
...  

2541 Background: Thrombocytopenia, or low platelet count, is a significant clinical problem associated with ITP, cancer chemotherapy, or other clinical settings. To avoid transfusions, agents that stimulate platelet production are in development. Clinical trials with recombinant versions of thrombopoietin (TPO), which stimulates platelet production in a lineage specific manner by binding to cMpl receptor (cMpl-R) on megakaryocytic progenitors, were demonstrated to increase platelet counts in humans. However, the possible generation of an anti-TPO immune response that cross-reacts with and impairs the function of the endogenous cytokine is a significant disadvantage of this treatment approach. Alternate thrombopoietic agents that lack native TPO primary sequences have been developed to address this concern. Methods: Using rational design, antibody fragments (Fabs) that mimic TPO were created. A peptide with cMpl-R binding capability was grafted into different CDRs of a fully human Fab scaffold. Functional presentation of the peptide was optimized using phage display and cell-based panning. Select antibodies and fragments containing two grafted peptides were assayed for their ability to stimulate cMpl-R in vitro. In vivo stimulation of platelet production was tested in normal mice injected daily for five days with either rhTPO (90 μg/kg) or Fab59 (0.2 mg/kg, 2 mg/kg or 5 mg/kg) or negative control Fab (5mg/kg). Results: Several candidates demonstrated agonist activity in an in vitro cMpl-R signaling reporter assay, including Fab59 which was estimated to be equipotent to TPO. In vivo, a rise in peripheral platelet counts comparable to rhTPO was seen with Fab59 at 2 mg/kg and 5 mg/kg. Serum antibodies generated in response to dosing with Fab59 did not cross-react with murine or human TPO. Conclusion: These rationally-designed mimetic Fabs may provide a therapeutic intervention for thrombocytopenia while avoiding the potential generation of neutralizing antibodies to endogenous TPO. [Table: see text]

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3622-3622
Author(s):  
Frederick Karl Racke ◽  
Maureen E Baird ◽  
Rolf Barth ◽  
Tianyao Huo ◽  
Weilian Yang ◽  
...  

Abstract Abstract 3622 Poster Board III-558 Despite recent advances in our understanding of megakaryocytic growth and platelet production, thrombocytopenia remains a difficult problem in the clinical management of patients with hematologic malignancies. Thrombopoietin (TPO) is the major cytokine involved in the normal production of platelets. However, the use of TPO has been relatively unsuccessful for the treatment of these patients and platelet transfusions remain the primary treatment for thrombocytopenia despite their significant cost and relatively short-lived responses. Thus, there remains an important clinical need for the development of novel approaches to generate platelets. Despite numerous reports on protein kinase C (PKC) agonists as promoters of megakaryocytic differentiation in leukemic cell lines and primary cells, little is known about their in vitro effects on primary CD34-selected progenitors or when administered in vivo. In the present study, we examine that effects of the novel PKC isoform agonist ingenol 3,20 dibenzoate (IDB) on megakaryocyte differentiation from CD34+ cells cultured in TPO and stem cell factor (SCF) or erythropoietin/SCF and its effects on platelet production in BALB/c mice. IDB potently stimulates early megakaryopoiesis and redirects the specificity of EPO to favor megakaryopoiesis over erythropoiesis. In contrast, broad spectrum PKC agonists such as phorbol myristate acetate, mezerein, and indolactam V fail to promote megakaryopoiesis. In vitro, IDB stimulates early expression of the promegakaryopoietic transcription factors egr1 and fli-1 and downregulates the proerythropoietic factors KLF1 and c-myb. Induction of the early megakaryocytic marker, CD9, was observed within the first 24 hrs of treatment with IDB and CD9 induction was blocked by the PKC inhibitor bisindolylmaleimide, which inhibits both novel and conventional PKC isoforms. In contrast, an inhibitor of conventional PKC isoforms, Gö6976, failed to block CD9 induction. In vivo, single intraperitoneal injections of IDB selectively increased platelet counts in BALB/c mice by 50% (plt= 630,000 vs. 985,000/μl; p<.005) at day 7 without affecting hemoglobin (Hgb) concentration or white counts (WBC). Mice treated with low dose radiation (2-4 Gy) had a transient drop in both platelet and WBC counts. Pretreatment with IDB 3 hrs prior to irradiation increased the platelet counts without improving WBC. More severe radiation exposure (6-8 Gy) causes pancytopenia. IDB treatment 3 hrs prior to 6 Gy irradiation significantly reduced the thrombocytopenia (plt=192,000 vs 594,000/μl; p<0.005) and anemia (hemoglobin=11.9 vs. 13.5gm/dl); p<0.005) without affecting the drop in WBC (WBC=1,200 vs. 1,300/μl; p=NS) at 14 days following irradiation. For mice treated with 8 Gy radiation, IDB pretreatment resulted in similar improvements in platelet counts (plt=111,000 vs. 443,000/μl; p<0.005) and hemoglobin (hgb=8.2 vs. 12.7 gm/dl; p<0.005) at 21 days following irradiation. The mitigation of thrombocytopenia is accompanied by marked increases in the megakaryocyte content in both the spleens and bone marrows of IDB-treated mice. Most importantly, IDB mitigated radiation-induced thrombocytopenia, even when administered 24 hrs after irradiation (plt=80,000 vs. 241,000/μl at 14 days following 6 Gy irradiation; p<0.01). Finally, IDB improved the survival of lethally irradiated mice. Our data suggest that the novel PKC isoform agonist IDB promotes the early differentiation of megakaryocytes from hematopoietic progenitors at the resulting in a significant improvement in platelet recovery following irradiation. IDB also improved Hgb levels following higher radiation doses. This may be due to improved hemostasis secondary to increased platelet numbers; however, an additional radioprotective effect on erythroid precursors cannot be excluded. These results strongly support our hypothesis that the novel PKC agonist IDB may be useful for the treatment of radiation and possibly drug-induced thrombocytopenia. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3696-3696
Author(s):  
Kazunori Murai ◽  
Shugo Kowata ◽  
Akiko Abo ◽  
Tatsuo Oyake ◽  
Kenichi Nomura ◽  
...  

Abstract Abstract 3696 Background: Bortezomib is potent and reversible proteasome inhibitor that has been extensively used for multiple myeloma. Several clinical studies demonstrated that overall response rates using bortezomib alone to relapsed or refractory patients with multiple myeloma were 33 to 50%. The most common grade 3 adverse event was a cyclic thrombocytopenia, which was reported in 20–30% of patients in several clinical studies. The mechanism by which bortezomib causes thrombocytopenia remains unknown. In this study, we evaluated the effect of bortezomib on megakaryocytic progenitor cells, megakaryocytopoiesis, megakaryocyte and platelet production in mice. Method: All animal procedures were approved by the Institutional Animal Care and Use Committee in Iwate Medical University. Male ddY at 8 weeks of age mice were used in all experiments. In vivo experiments: (a) The mice received 2.5 mg/kg bortezomib via tail-vein injection. Blood was obtained and the following experiments were carried out at day 2, 4, 6, 8, 10 after intravenous injection (n=9, each group). Complete blood counts were measured. Reticulated platelet (RP) was analyzed by flow cytometry using thiazole orange (TO) to evaluate platelet kinetics. Plasma TPO level were measured by ELISA. Bone marrow megakaryocyte's number and morphology from femur in bortezomib- and control-treated mice were observed by microscopy. Femur was fixed in 10% buffered formalin, decalcificated, embedded in paraffin and stained for Hematoxylin-Eosin (H-E). (b) Bortezomib (2.5 mg/kg) was administrated via tail-vein to mice. After 24hr, bone marrow cells were cultured in MegaCult®-C at 5% CO2 and 20% O2for 7 days. The megakaryocytic colonies (CFU-Megs-in vivo) were counted. In vitro experiments: (c) Bone marrow cells, obtained from non-treated mice, were cultured at 37°C in 5% CO2and 20% O2 for 7 days with bortezomib (0.01, 0.1, 1, 10, 100 ng/ml). CFU-Megs were counted (CFU-Megs-in vitro). (d) Proplatelet formation: Murine megakarocytes were partially purified from bone marrow using BSA gradient. They were plated in 96 micro-well culture plates (300 megakaryocyte)well) and cultured in IMDM in duplicates, supplemented with 1 × ITS-G (Life technologies) and each concentration of bortezomib (0.01, 0.1, 1, 10, 100 ng/ml), at 37°C in 5% CO2and 20% O2. After 24 hr incubation, the megakaryocytes with proplatelets in each well were counted. Results: (a) Control mice did not have any significant change in platelet counts, % reticulated platelets and plasma TPO levels at days 0, 2, 4, 6, 8, 10. While, bortezomib treated mice (2.5mg/kg) had a significant reduction in platelet counts at day 2 (470 ± 210 × 109/L. P<0.001), at day 4 (667 ± 118 × 109/L, P<0.001). The platelet counts returned to normal value at day 6 (903 ± 548 × 109/L) and day 10 (1122 ± 187 × 109/L). RP (%) began to increase at day 6 (8.8 ± 4.0 %). Plasma TPO levels tend to increase at day 4. Means megakaryocytes's number in one field of femur was similar in between bortezomib non-treated and –treated mice. The megakaryocytes were similar in morphology at each day, too. (b) CFU-Megs-in vivo were similar in number between bortezomib non-treated and –treated mice (38.0 ± 6.1 vs 34.5 ± 5.6 per 1 × 105 bone marrow cells respectively). (c) CFU-Megs-in vitro were not decreased significantly at 0.001 to 1 ng/ml and decreased significantly (p<0.01) at 10 and 100 ng/ml of bortezomib. (d) Proplatelet formation (PPF) were decreased significantly at 0.01, 0.1, 1, 10, 100 ng/ml bortezomib (0 mg)ml: 25.2 ± 4.8%, 0.01ng/ml: 23.8 ± 4.9%, 0.1 ng/ml: 18.4 ± 3.1% p<0.01, 1 ng/ml: 13.2 ± 3.8% p<0.001, 10 ng/ml: 13.3 ± 2.1% p<0.001, 100ng/ml: 5.9 ± 1.4 % p<0.001). Discussion & Conclusion: Bortezomib did not adversely affect on megakaryocytic prognitors nor megakaryocytes. It did inhibit PPF, that is, the step of platelet production, even when bortezomib plasma concentration levels have gone down. Plasma TPO level showed an inverse relationship against circulating platelet counts. Based on the evidence in which Cmax of plasma bortezomib concentration was under 100 ng/ml in bortezomib-injected mice (2.5mg/kg), bortezomib induced thrombocytopenia might be due to the inhibition of proplatelet formation of megakaryocyte. Disclosures: No relevant conflicts of interest to declare.


Inorganics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 128 ◽  
Author(s):  
Giglio ◽  
Rey

Technetium-99m has a rich coordination chemistry that offers many possibilities in terms of oxidation states and donor atom sets. Modifications in the structure of the technetium complexes could be very useful for fine tuning the physicochemical and biological properties of potential 99mTc radiopharmaceuticals. However, systematic study of the influence of the labelling strategy on the “in vitro” and “in vivo” behaviour is necessary for a rational design of radiopharmaceuticals. Herein we present a review of the influence of the Tc complexes’ molecular structure on the biodistribution and the interaction with the biological target of potential nitroimidazolic hypoxia imaging radiopharmaceuticals presented in the literature from 2010 to the present. Comparison with the gold standard [18F]Fluoromisonidazole (FMISO) is also presented.


2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Meilin Chan ◽  
Licun Wu ◽  
Zhihong Yun ◽  
Trevor D. McKee ◽  
Michael Cabanero ◽  
...  

AbstractMalignant pleural mesothelioma (MPM) is an aggressive neoplasm originating from the pleura. Non-epithelioid (biphasic and sarcomatoid) MPM are particularly resistant to therapy. We investigated the role of the GITR-GITRL pathway in mediating the resistance to therapy. We found that GITR and GITRL expressions were higher in the sarcomatoid cell line (CRL5946) than in non-sarcomatoid cell lines (CRL5915 and CRL5820), and that cisplatin and Cs-137 irradiation increased GITR and GITRL expressions on tumor cells. Transcriptome analysis demonstrated that the GITR-GITRL pathway was promoting tumor growth and inhibiting cell apoptosis. Furthermore, GITR+ and GITRL+ cells demonstrated increased spheroid formation in vitro and in vivo. Using patient derived xenografts (PDXs), we demonstrated that anti-GITR neutralizing antibodies attenuated tumor growth in sarcomatoid PDX mice. Tumor immunostaining demonstrated higher levels of GITR and GITRL expressions in non-epithelioid compared to epithelioid tumors. Among 73 patients uniformly treated with accelerated radiation therapy followed by surgery, the intensity of GITR expression after radiation negatively correlated with survival in non-epithelioid MPM patients. In conclusion, the GITR-GITRL pathway is an important mechanism of autocrine proliferation in sarcomatoid mesothelioma, associated with tumor stemness and resistance to therapy. Blocking the GITR-GITRL pathway could be a new therapeutic target for non-epithelioid mesothelioma.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhou Fang ◽  
Junjian Chen ◽  
Ye Zhu ◽  
Guansong Hu ◽  
Haoqian Xin ◽  
...  

AbstractPeptides are widely used for surface modification to develop improved implants, such as cell adhesion RGD peptide and antimicrobial peptide (AMP). However, it is a daunting challenge to identify an optimized condition with the two peptides showing their intended activities and the parameters for reaching such a condition. Herein, we develop a high-throughput strategy, preparing titanium (Ti) surfaces with a gradient in peptide density by click reaction as a platform, to screen the positions with desired functions. Such positions are corresponding to optimized molecular parameters (peptide densities/ratios) and associated preparation parameters (reaction times/reactant concentrations). These parameters are then extracted to prepare nongradient mono- and dual-peptide functionalized Ti surfaces with desired biocompatibility or/and antimicrobial activity in vitro and in vivo. We also demonstrate this strategy could be extended to other materials. Here, we show that the high-throughput versatile strategy holds great promise for rational design and preparation of functional biomaterial surfaces.


2021 ◽  
Vol 19 ◽  
pp. 228080002198969
Author(s):  
Min-Xia Zhang ◽  
Wan-Yi Zhao ◽  
Qing-Qing Fang ◽  
Xiao-Feng Wang ◽  
Chun-Ye Chen ◽  
...  

The present study was designed to fabricate a new chitosan-collagen sponge (CCS) for potential wound dressing applications. CCS was fabricated by a 3.0% chitosan mixture with a 1.0% type I collagen (7:3(w/w)) through freeze-drying. Then the dressing was prepared to evaluate its properties through a series of tests. The new-made dressing demonstrated its safety toward NIH3T3 cells. Furthermore, the CCS showed the significant surround inhibition zone than empty controls inoculated by E. coli and S. aureus. Moreover, the moisture rates of CCS were increased more rapidly than the collagen and blank sponge groups. The results revealed that the CCS had the characteristics of nontoxicity, biocompatibility, good antibacterial activity, and water retention. We used a full-thickness excisional wound healing model to evaluate the in vivo efficacy of the new dressing. The results showed remarkable healing at 14th day post-operation compared with injuries treated with collagen only as a negative control in addition to chitosan only. Our results suggest that the chitosan-collagen wound dressing were identified as a new promising candidate for further wound application.


2021 ◽  
Vol 7 (6) ◽  
pp. eaba2458
Author(s):  
Weier Bao ◽  
Falin Tian ◽  
Chengliang Lyu ◽  
Bin Liu ◽  
Bin Li ◽  
...  

The poor understanding of the complex multistep process taken by nanocarriers during the delivery process limits the delivery efficiencies and further hinders the translation of these systems into medicine. Here, we describe a series of six self-assembled nanocarrier types with systematically altered physical properties including size, shape, and rigidity, as well as both in vitro and in vivo analyses of their performance in blood circulation, tumor penetration, cancer cell uptake, and anticancer efficacy. We also developed both data and simulation-based models for understanding the influence of physical properties, both individually and considered together, on each delivery step and overall delivery process. Thus, beyond finding that nanocarriers that are simultaneously endowed with tubular shape, short length, and low rigidity outperformed the other types, we now have a suit of theoretical models that can predict how nanocarrier properties will individually and collectively perform in the multistep delivery of anticancer therapies.


Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1597
Author(s):  
Thuong Thi Ho ◽  
Van Thi Pham ◽  
Tra Thi Nguyen ◽  
Vy Thai Trinh ◽  
Tram Vi ◽  
...  

Nanodiamond (ND) has recently emerged as a potential nanomaterial for nanovaccine development. Here, a plant-based haemagglutinin protein (H5.c2) of A/H5N1 virus was conjugated with detonation NDs (DND) of 3.7 nm in diameter (ND4), and high-pressure and high-temperature (HPHT) oxidative NDs of ~40–70 nm (ND40) and ~100–250 nm (ND100) in diameter. Our results revealed that the surface charge, but not the size of NDs, is crucial to the protein conjugation, as well as the in vitro and in vivo behaviors of H5.c2:ND conjugates. Positively charged ND4 does not effectively form stable conjugates with H5.c2, and has no impact on the immunogenicity of the protein both in vitro and in vivo. In contrast, the negatively oxidized NDs (ND40 and ND100) are excellent protein antigen carriers. When compared to free H5.c2, H5.c2:ND40, and H5.c2:ND100 conjugates are highly immunogenic with hemagglutination titers that are both 16 times higher than that of the free H5.c2 protein. Notably, H5.c2:ND40 and H5.c2:ND100 conjugates induce over 3-folds stronger production of both H5.c2-specific-IgG and neutralizing antibodies against A/H5N1 than free H5.c2 in mice. These findings support the innovative strategy of using negatively oxidized ND particles as novel antigen carriers for vaccine development, while also highlighting the importance of particle characterization before use.


Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 861
Author(s):  
Elizabeth E. Niedert ◽  
Chenghao Bi ◽  
Georges Adam ◽  
Elly Lambert ◽  
Luis Solorio ◽  
...  

A microrobot system comprising an untethered tumbling magnetic microrobot, a two-degree-of-freedom rotating permanent magnet, and an ultrasound imaging system has been developed for in vitro and in vivo biomedical applications. The microrobot tumbles end-over-end in a net forward motion due to applied magnetic torque from the rotating magnet. By turning the rotational axis of the magnet, two-dimensional directional control is possible and the microrobot was steered along various trajectories, including a circular path and P-shaped path. The microrobot is capable of moving over the unstructured terrain within a murine colon in in vitro, in situ, and in vivo conditions, as well as a porcine colon in ex vivo conditions. High-frequency ultrasound imaging allows for real-time determination of the microrobot’s position while it is optically occluded by animal tissue. When coated with a fluorescein payload, the microrobot was shown to release the majority of the payload over a 1-h time period in phosphate-buffered saline. Cytotoxicity tests demonstrated that the microrobot’s constituent materials, SU-8 and polydimethylsiloxane (PDMS), did not show a statistically significant difference in toxicity to murine fibroblasts from the negative control, even when the materials were doped with magnetic neodymium microparticles. The microrobot system’s capabilities make it promising for targeted drug delivery and other in vivo biomedical applications.


1997 ◽  
Vol 8 (2) ◽  
pp. 175-200 ◽  
Author(s):  
H.F. Jenkinson ◽  
RJ Lamont

Streptococci express arrays of adhesins on their cell surfaces that facilitate adherence to substrates present in their natural environment within the mammalian host. A consequence of such promiscuous binding ability is that streptococcal cells may adhere simultaneously to a spectrum of substrates, including salivary glycoproteins, extracellular matrix and serum components, host cells, and other microbial cells. The multiplicity of streptococcal adherence interactions accounts, at least in part, for their success in colonizing the oral and epithelial surfaces of humans. Adhesion facilitates colonization and may be a precursor to tissue invasion and immune modulation, events that presage the development of disease. Many of the streptococcal adhesins and virulence-related factors are cell-wall-associated proteins containing repeated sequence blocks of amino acids. Linear sequences, both within the blocks and within non-repetitive regions of the proteins, have been implicated in substrate binding. Sequences and functions of these proteins among the streptococci have become assorted through gene duplication and horizontal transfer between bacterial populations. Several adhesins identified and characterized through in vitro binding assays have been analyzed for in vivo expression and function by means of animal models used for colonization and virulence. Information on the molecular structure of adhesins as related to their in vivo function will allow for the rational design of novel acellular vaccines, recombinant antibodies, and adhesion agonists for the future control or prevention of streptococcal colonization and streptococcal diseases.


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