Microneedle array delivered recombinant coronavirus vaccines: Immunogenicity and rapid translational development

BACKGROUND

Coronaviruses pose a serious threat to global health as evidenced by Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), and COVID-19. SARS Coronavirus (SARS-CoV), MERS Coronavirus (MERS-CoV), and the novel coronavirus, previously dubbed 2019-nCoV, and now officially named SARS-CoV-2, are the causative agents of the SARS, MERS, and COVID-19 disease outbreaks, respectively. Safe vaccines that rapidly induce potent and long-lasting virus-specific immune responses against these infectious agents are urgently needed. The coronavirus spike (S) protein, a characteristic structural component of the viral envelope, is considered a key target for vaccines for the prevention of coronavirus infection.

METHODS

We first generated codon optimized MERS-S1 subunit vaccines fused with a foldon trimerization domain to mimic the native viral structure. In variant constructs, we engineered immune stimulants (RS09 or flagellin, as TLR4 or TLR5 agonists, respectively) into this trimeric design. We comprehensively tested the pre-clinical immunogenicity of MERS-CoV vaccines in mice when delivered subcutaneously by traditional needle injection, or intracutaneously by dissolving microneedle arrays (MNAs) by evaluating virus specific IgG antibodies in the serum of vaccinated mice by ELISA and using virus neutralization assays. Driven by the urgent need for COVID-19 vaccines, we utilized this strategy to rapidly develop MNA SARS-CoV-2 subunit vaccines and tested their pre-clinical immunogenicity in vivo by exploiting our substantial experience with MNA MERS-CoV vaccines.

FINDINGS

Here we describe the development of MNA delivered MERS-CoV vaccines and their pre-clinical immunogenicity. Specifically, MNA delivered MERS-S1 subunit vaccines elicited strong and long-lasting antigen-specific antibody responses. Building on our ongoing efforts to develop MERS-CoV vaccines, promising immunogenicity of MNA-delivered MERS-CoV vaccines, and our experience with MNA fabrication and delivery, including clinical trials, we rapidly designed and produced clinically-translatable MNA SARS-CoV-2 subunit vaccines within 4 weeks of the identification of the SARS-CoV-2 S1 sequence. Most importantly, these MNA delivered SARS-CoV-2 S1 subunit vaccines elicited potent antigen-specific antibody responses that were evident beginning 2 weeks after immunization.

INTERPRETATION

MNA delivery of coronaviruses-S1 subunit vaccines is a promising immunization strategy against coronavirus infection. Progressive scientific and technological efforts enable quicker responses to emerging pandemics. Our ongoing efforts to develop MNA-MERS-S1 subunit vaccines enabled us to rapidly design and produce MNA SARS-CoV-2 subunit vaccines capable of inducing potent virus-specific antibody responses. Collectively, our results support the clinical development of MNA delivered recombinant protein subunit vaccines against SARS, MERS, COVID-19, and other emerging infectious diseases.

Redox Epiphospholipidome in Programmed Cell Death Signaling: Catalytic Mechanisms and Regulation

A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane building blocks. Indeed, a number of signaling functions of (phospho)lipid molecules has been discovered. Among these signaling lipids, a particular group of oxygenated polyunsaturated fatty acids (PUFA), so called lipid mediators, has been thoroughly investigated over several decades. This group includes oxygenated octadecanoids, eicosanoids, and docosanoids and includes several hundreds of individual species. Oxygenation of PUFA can occur when they are esterified into major classes of phospholipids. Initially, these events have been associated with non-specific oxidative injury of biomembranes. An alternative concept is that these post-synthetically oxidatively modified phospholipids and their adducts with proteins are a part of a redox epiphospholipidome that represents a rich and versatile language for intra- and inter-cellular communications. The redox epiphospholipidome may include hundreds of thousands of individual molecular species acting as meaningful biological signals. This review describes the signaling role of oxygenated phospholipids in programs of regulated cell death. Although phospholipid peroxidation has been associated with almost all known cell death programs, we chose to discuss enzymatic pathways activated during apoptosis and ferroptosis and leading to peroxidation of two phospholipid classes, cardiolipins (CLs) and phosphatidylethanolamines (PEs). This is based on the available LC-MS identification and quantitative information on the respective peroxidation products of CLs and PEs. We focused on molecular mechanisms through which two proteins, a mitochondrial hemoprotein cytochrome c (cyt c), and non-heme Fe lipoxygenase (LOX), change their catalytic properties to fulfill new functions of generating oxygenated CL and PE species. Given the high selectivity and specificity of CL and PE peroxidation we argue that enzymatic reactions catalyzed by cyt c/CL complexes and 15-lipoxygenase/phosphatidylethanolamine binding protein 1 (15LOX/PEBP1) complexes dominate, at least during the initiation stage of peroxidation, in apoptosis and ferroptosis. We contrast cell-autonomous nature of CLox signaling in apoptosis correlating with its anti-inflammatory functions vs. non-cell-autonomous ferroptotic signaling facilitating pro-inflammatory (necro-inflammatory) responses. Finally, we propose that small molecule mechanism-based regulators of enzymatic phospholipid peroxidation may lead to highly specific anti-apoptotic and anti-ferroptotic therapeutic modalities.

Second-generation Probiotics Producing IL-22 Increase Survival of Mice After Total Body Irradiation

BACKGROUND/AIM

Intestinal damage induced by total body irradiation (TBI) reduces leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5)-expressing stem cells, goblet, and Paneth cells, breaching the epithelial lining, and facilitating bacterial translocation, sepsis, and death.

MATERIALS AND METHODS

Survival was measured after TBI in animals that received wild-type or recombinant bacteria producing interleukin-22 (IL-22). Changes in survival due to microbially delivered IL-22 were measured. Lactobacillus reuteri producing IL-22, or Escherichia coli-IL-22 were compared to determine which delivery system is better.

RESULTS

C57BL/6 mice receiving IL-22 probiotics at 24 h after 9.25 Gy TBI, demonstrated green fluorescent protein-positive bacteria in the intestine, doubled the number of Lgr5+ intestinal stem cells, and increased 30-day survival. Bacteria were localized to the jejunum, ileum, and colon.

CONCLUSION

Second-generation probiotics appear to be valuable for mitigation of TBI, and radiation protection during therapeutic total abdominal irradiation.

Fanconi Anemia Mouse Genotype-specific Mitigation of Total Body Irradiation by GS-Nitroxide JP4-039

BACKGROUND/AIM

Radiation mitigator, GS-nitroxide, JP4-039, was evaluated for mitigation of total body irradiation (TBI) in Fanconi anemia (FA) Fancd2^-/- (129/Sv), Fancg^-/- (B6), and Fanca^-/- (129/Sv) mice.

MATERIALS AND METHODS

JP4-039 dissolved in 30% 2-hydroxypropyl-β-cyclodextrin was injected intramuscularly 24 h after total body irradiation (9.25 Gy) into Fanca^-/-, Fancd2^-/- and Fancg^-/- mice. Irradiation survival curves were performed in vitro using bone marrow stromal cell lines derived from Fanca^-/-, Fancd2^-/- and Fancg^-/- mice.

RESULTS

FA mice demonstrate genotype specific differences in TBI mitigation by JP4-039. Radiation effects in derived bone marrow stromal cell lines in vitro were mitigated by drugs that block apoptosis, but not necroptosis or ferroptosis.

CONCLUSION

FA mouse models are valuable for elucidating DNA repair pathways in cell and tissue responses to TBI, and the role of drugs that target distinct cell death pathways.

Amelioration of Mucositis in Proton Therapy of Fanconi Anemia Fanca-/- Mice by JP4-039

BACKGROUND/AIM

We tested JP4-039, a GS-nitroxide radiation damage mitigator in proton therapy of Fanconi anemia (FA) mice.

MATERIALS AND METHODS

Fanca-/- and Fanca+/+ bone marrow stromal cells were pre-treated with JP4-039 and irradiated with either protons or photons (0-10 GyRBE) followed by clonogenic survival and β-Galactosidase senescence analysis. Fanca-/- and Fanca+/+ mice were pretreated with JP4-039 for 10 min prior to oropharyngeal irradiation with either protons or photons (0 or 30 GyRBE) followed by sacrifice and measurement of oral cavity ulceration, distant hematopoietic suppression, and real-time polymerase chain reaction analysis.

RESULTS

JP4-039 reduced oral cavity ulceration in Fanca-/- mice, transcripts Nfkb, Ap1, Sp1, and Nrf2, and proton therapy induced distant marrow suppression.

CONCLUSION

JP4-039 protected Fanca-/- and Fanca+/+ cells and mouse oral cavity from both proton and photon radiation.

Radioresistance of Serpinb3a-/- Mice and Derived Hematopoietic and Marrow Stromal Cell Lines

Serpins are a group of serine-proteases involved in multiple signal transduction pathways in mammalian cells. In particular, Serpinb3a is involved in the lysosomal necrosis cell death pathway with components that overlap with radiation-induced apoptosis. We investigated the radiation response of Serpinb3a-/- mice compared to Serpinb3a+/+ mice on the Balb/c background. Serpinb3a-/- mice showed significant radioresistance to a dose of 8.0 Gy total-body irradiation, compared to Serpinb3a+/+ Balb/c mice. Long-term bone marrow cultures from Serpinb3a-/- mice showed increased longevity. In clonogenic survival assays, fresh bone marrow hematopoietic progenitors, as well as clonal interleukin-3 (IL-3)-dependent hematopoietic progenitor and bone marrow stromal cell lines from Serpinb3a-/- mice were radioresistant. Serpinb3a-/- mouse bone marrow-derived stromal cell lines had increased baseline and postirradiation antioxidant capacity. Serpinb3a-/- bone marrow stromal cells showed increased radiation-induced RNA transcripts for MnSOD and p21, and decreased levels of p53 and TGF-b. Both irradiated Serpinb3a-/- mouse bone marrow stromal cell lines and plasma removed from total-body irradiated mice had decreased levels of expression of stress response and inflammation-associated proteins. Abrogation of Serpinb3a may be a potential new target for mitigation of radiation effects.

Abstract 5155: Increased longevity of continuous bone marrow cultures and radioresistance of bone marrow stromal cells from SOD193A ALS (Amyotrophic Lateral Sclerosis) mice

Introduction: The SOD1G93A mouse model of ALS, demonstrates hind limb paralysis beginning at 90 - 100 days of age with stage 4 paralysis at 125 days of age and progressive neuromuscular loss.

Materials and Methods: To determine whether deficiency of functional SOD1 influenced parameters of hematopoiesis, long-term bone marrow cultures were established from ALS and control mice. Bone marrow stromal cell lines derived from LTBMCs were tested for clonogenic radiation survival. We tested the effect of bone marrow transplant after total body irradiation on delay of paralysis.

Results: SOD1G93A marrow cultures demonstrated significant increase in production of hematopoietic progenitor cells (p < 0.0001) and overall longevity of production of hematopoietic cells (p = 0.0354), and bone marrow stromal cell lines were significantly radioresistant (D0 = 1.33 ± 0.09, and ñ = 8.57 ± 1.8) compared to control C57BL/6J mice (D0 = 1.59 ± 0.11, p = 0.117; and ñ = 3.4 ± 0.4, p= 0.0466). Total body irradiation and bone marrow transplantation with GFP+ donor marrow demonstrated a significant increase in paralysis free interval from 129.2 ± 3.0 to 240.7 ± 21.1 days (p = 0.0010), normalization of blood/brain barrier permeability, and increase in M2 marrow origin microglial cells in proximity to degenerating anterior horn cell/motor neurons. Isolated brain and spinal cord irradiation did not prolong the paralysis free interval (129.0 ± 2.7 days, p = 0.7748).

Conclusions: The results of hematopoiesis in LTBMCs in the absence of functional SOD1 showed improved LTBMC longevity and radioresistance of marrow stromal cells both unexpected pleiotropic effects of the SOD1G93A genotype. Marrow transplant after TBI prolonged the paralysis free interval in ALS mice.

Citation Format: Andrew Henderson, Michael W. Epperly, Renee Fisher, Donna Shields, Lora Rigatti, Christopher Donnelly, Simon Watkins, Joel S. Greenberger. Increased longevity of continuous bone marrow cultures and radioresistance of bone marrow stromal cells from SOD193A ALS (Amyotrophic Lateral Sclerosis) mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5155.

Redox (phospho)lipidomics of signaling in inflammation and programmed cell death

In addition to the known prominent role of polyunsaturated (phospho)lipids as structural blocks of biomembranes, there is an emerging understanding of another important function of these molecules as a highly diversified signaling language utilized for intra- and extracellular communications. Technological developments in high-resolution mass spectrometry facilitated the development of a new branch of metabolomics, redox lipidomics. Analysis of lipid peroxidation reactions has already identified specific enzymatic mechanisms responsible for the biosynthesis of several unique signals in response to inflammation and regulated cell death programs. Obtaining comprehensive information about millions of signals encoded by oxidized phospholipids, represented by thousands of interactive reactions and pleiotropic (patho)physiological effects, is a daunting task. However, there is still reasonable hope that significant discoveries, of at least some of the important contributors to the overall overwhelmingly complex network of interactions triggered by inflammation, will lead to the discovery of new small molecule regulators and therapeutic modalities. For example, suppression of the production of AA-derived pro-inflammatory mediators, HXA3 and LTB4, by an iPLA2 γ inhibitor, R-BEL, mitigated injury associated with the activation of pro-inflammatory processes in animals exposed to whole-body irradiation. Further, technological developments promise to make redox lipidomics a powerful approach in the arsenal of diagnostic and therapeutic instruments for personalized medicine of inflammatory diseases and conditions.

Amelioration of Amyotrophic Lateral Sclerosis in SOD1G93A Mice by M2 Microglia from Transplanted Marrow

Background/Aim: The cause of fatal neuromuscular amyotrophic lateral sclerosis (ALS) is not known. Materials and Methods: Ninety-day-old superoxide-dismutase-1 G93A (SOD1 G93A ) mice demonstrating level 1 paralysis, received 9.0 Gy total body irradiation (TBI) from a cesium source at 340 cGy per minute, and intravenous transplantation with 1×10 6 C57BL/6 green fluorescent protein (GFP)+ donor bone marrow cells. Results: Paralysis-free survival was prolonged in TBI and bone marrow-transplanted SOD1 G93A mice from 100 to over 250 days (p=0.0018). Other mice transplanted with SOD1 G93A marrow or marrow treated with the free-radical scavenger MMS350 showed no therapeutic effect. GFP+ macrophage-2 (M2) microglial cells of bone marrow origin, were seen at sites of degenerating anterior horn motor neurons. SOD1 G93A mice had a disruption in the blood-brain barrier permeability which was reversed by marrow transplant from C57BL/6 mice. SOD1 G93A marrow showed unexpected robust hematopoiesis in vitro, and radioresistance. Conclusion: After TBI, M2 microglial cells from transplanted donor marrow extended the paralysis-free interval in SOD1 G93A mice.

Adipose-Derived Stem Cell Therapy Ameliorates Ionizing Irradiation Fibrosis via Hepatocyte Growth Factor-Mediated Transforming Growth Factor-β Downregulation and Recruitment of Bone Marrow Cells

Radiation therapy to anatomic regions, including the head and neck, chest wall, and extremities, can produce radiation-induced fibrosis (RIF). To elucidate the cellular and molecular mechanism(s) involved in RIF, female C57BL/6J mice were irradiated to the right flank to 35 Gy in single fraction using 6 Mv electrons. Radiation fibrosis was detected by day 14, was increased by day 28, and confirmed by Masson's trichrome histological staining for collagen. Biopsied tissue at day 14 showed an increase in expression of fibrosis-related genes including transforming growth factor-β (TGF-β) and collagens 1-6. A single adipose-derived stem cell (ASC) injection on day 28 at the irradiated site decreased by day 40: epithelial thickness, collagen deposition, and significantly improved limb excursion compared with irradiated controls. Noncontact transwell coculture of ASCs above a monolayer of irradiated human foreskin fibroblasts downregulated fibrosis-related genes TGF-β, connective tissue growth factor, interleukin-1, NF-kB, tumor necrosis factor, and collagens 1-6. Hepatocyte growth factor (HGF) secreted by ASCs was identified as a novel mechanism by which ASCs exert antifibrotic effects by downregulating fibrotic gene expression in irradiated cells and recruiting bone marrow cells to the irradiated site. In conclusion, these data indicate a mechanistic role of HGF secreted by ASCs in reducing RIF. Stem Cells 2019;37:791-802.

Malignant Transformation of Fanconi Anemia Complementation Group D2-deficient (Fancd2 -/-) Hematopoietic Progenitor Cells by a Single HPV16 Oncogene

AIM

To demonstrate that Fanconi anemia complementation group D2-deficient (Fancd2^-/-) hematopoietic progenitor cell lines can be transformed by transfection with a plasmid containing either the E6 or E7 oncogene of human papillomavirus (HPV) to generate malignant plasmacytoma-inducing cell lines.

MATERIALS AND METHODS

In order to determine whether a single HPV type 16 (HPV16) oncogene induced malignant transformation, Fancd2^-/- and Fancd2^+/+ interleukin 3 (IL3)-dependent hematopoietic progenitor cell lines were transfected with plasmids containing E6 or E7 oncogene, or control empty plasmid.

RESULTS

Fancd2^-/- but not Fancd2^+/+ cells were transformed into malignant IL3-independent cells by both E6, and E7 oncogenes, but not by empty plasmid. Hematopoietic cell lines and tumors induced by Fancd2^-/- E6 and Fancd2^-/- E7 cell lines were positive for each respective HPV RNA and protein.

CONCLUSION

A single HPV16 oncogene is adequate to produce malignant transformation of Fancd2^-/- hematopoietic cells.

Continuous One Year Oral Administration of the Radiation Mitigator, MMS350, after Total-Body Irradiation, Restores Bone Marrow Stromal Cell Proliferative Capacity and Reduces Senescence in Fanconi Anemia (Fanca-/-) Mice

We quantitated age-related accumulation of senescent cells in irradiated Fanconi anemia (FA) (Fanca^-/- mouse cell lines in vitro, and monitored the effect of continuous administration (via drinking water) of the water-soluble radiation mitigator, MMS350, on tissues in vivo over one year after 7.5 Gy total-body irradiation (TBI). Irradiated Fanca^-/- mouse bone marrow stromal cell lines showed increased numbers of beta-galactosidase- and p21-positive senescent cells compared to Fanca^+/+ cell lines, which was reduced by MMS350. One week after 7.5 Gy TBI, Fanca^-/- mice showed increased numbers of senescent cells in spleen compared to Fanca^+/+ controls, decreased bone marrow cellularity, failure of explanted bone marrow to proliferate in vitro to form a hematopoietic microenvironment and no detectable single stromal cell cloning capacity. There was no detectable amelioration by MMS350 administration at one week. In contrast, one year post-TBI, Fanca^-/- mice demonstrated fewer senescent cells in brain and spleen compared to Fanca^+/+ controls. While Fanca^-/- mouse bone marrow stromal cells explanted one year post-TBI still failed to proliferate in vitro, continuous oral administration of 400 µ M, MMS350 in drinking water restored explanted stromal cell proliferation. The data indicate that continuous administration of MMS350 modulated several properties of TBI-accelerated aging in Fanca^-/- mice as well as control mice, and support further study of MMS350 as a modulator of radiation late effects.

Synthesis and Evaluation of a Mitochondria-Targeting Poly(ADP-ribose) Polymerase-1 Inhibitor

The poly(ADP-ribose) polymerase (PARP) family of enzymes plays a crucial role in cellular and molecular processes including DNA damage detection and repair and transcription; indeed, PARP inhibitors are under clinical evaluation as chemotherapeutic adjuncts given their capacity to impede genomic DNA repair in tumor cells. Conversely, overactivation of PARP can lead to NAD⁺ depletion, mitochondrial energy failure, and cell death. Since PARP activation facilitates genomic but impedes mitochondrial DNA repair, nonselective PARP inhibitors are likely to have opposing effects in these cellular compartments. Herein, we describe the synthesis and evaluation of the mitochondria-targeting PARP inhibitor, XJB-veliparib. Attachment of the hemigramicidin S pentapeptide isostere for mitochondrial targeting using a flexible linker at the primary amide site of veliparib did not disrupt PARP affinity or inhibition. XJB-veliparib was effective at low nanomolar concentrations (10-100 nM) and more potent than veliparib in protection from oxygen-glucose deprivation (OGD) in primary cortical neurons. Both XJB-veliparib and veliparib (10 nM) preserved mitochondrial NAD⁺ after OGD; however, only XJB-veliparib prevented release of NAD⁺ into cytosol. XJB-veliparib (10 nM) appeared to inhibit poly(ADP-ribose) polymer formation in mitochondria and preserve mitochondrial cytoarchitecture after OGD in primary cortical neurons. After 10 nM exposure, XJB-veliparib was detected by LC-MS in mitochondria but not nuclear-enriched fractions in neurons and was observed in mitoplasts stripped of the outer mitochondrial membrane obtained from HT22 cells. XJB-veliparib was also effective at preventing glutamate-induced HT22 cell death at micromolar concentrations. Importantly, in HT22 cells exposed to H₂O₂ to produce DNA damage, XJB-veliparib (10 μM) had no effect on nuclear DNA repair, in contrast to veliparib (10 μM) where DNA repair was retarded. XJB-veliparib and analogous mitochondria-targeting PARP inhibitors warrant further evaluation in vitro and in vivo, particularly in conditions where PARP overactivation leads to mitochondrial energy failure and maintenance of genomic DNA integrity is desirable, e.g., ischemia, oxidative stress, and radiation exposure.

Evaluation of Different Formulations and Routes for the Delivery of the Ionizing Radiation Mitigator GS-Nitroxide (JP4-039)

BACKGROUND/AIM

The mitochondrial targeted GS-nitroxide, JP4-039, is an effective total body irradiation (TBI) mitigator when delivered intravenously (IV) up to 72 h after exposure. Effective systemic and localized administration to oral cavity/oropharynx and esophagus has been demonstrated. The objective of the study was to establish alternatives to IV administration suitable for JP4-039 delivery to mass casualties.

MATERIALS AND METHODS

JP4-039 was administered to C57BL/6 mice by topically applied carboxy-methyl-cellulose microneedle arrays (MNAs) or by intramuscular (IM) injection. Three different formulations that have passed Food and Drug Administration review, namely Captisol, 2-hydroxypropyl-β-cyclodextrin (cyclodextrin), and Miglyol-812-N, were used for drug delivery. Intraoral (IO) administration with each formulation was also evaluated.

RESULTS

All tested formulations and MNAs successfully delivered JP4-039. However, IM delivery of the Miglyol-812-N displayed very efficient and highly reproducible radiation mitigation.

CONCLUSION

Effective IM delivery of JP4-039 in animal models after TBI or partial-body irradiation suggested the use of the Miglyol-812-N formulation in both medical indications and radiation countermeasures.

Targeting Mitochondrial Oxidative Stress to Mitigate UV-Induced Skin Damage

Unmitigated UV radiation (UVR) induces skin photoaging and multiple forms of cutaneous carcinoma by complex pathways that include those mediated by UV-induced reactive oxygen species (ROS). Upon UVR exposure, a cascade of events is induced that overwhelms the skin’s natural antioxidant defenses and results in DNA damage, intracellular lipid and protein peroxidation, and the dysregulation of pathways that modulate inflammatory and apoptotic responses. To this end, natural products with potent antioxidant properties have been developed to prevent, mitigate, or reverse this damage with varying degrees of success. Mitochondria are particularly susceptible to ROS and subsequent DNA damage as they are a major intracellular source of oxidants. Therefore, the development of mitochondrially targeted agents to mitigate mitochondrial oxidative stress and resulting DNA damage is a logical approach to prevent and treat UV-induced skin damage. We summarize evidence that some existing natural products may reduce mitochondrial oxidative stress and support for synthetically generated mitochondrial targeted cyclic nitroxides as potential alternatives for the prevention and mitigation of UVR-induced skin damage.

Development of tensile strength methodology for murine skin wound healing

In this study, a methodology was evaluated and improved to quickly measure the tensile strength of murine skin in a biomechanical assay for an incisional wound healing model. The aim was to streamline and enhance the wound model, skin specimen preparation, and tensile test so that large numbers of fresh tissue could be tested reliably and rapidly. Linear incisions of 25-mm length were made in the dorsal skin of mice along the spine and metallic staples were used to close the wound. After 20 days, the mice were sacrificed, and a square-shaped section of skin containing the linear incision was excised. Two metallic punches were fabricated and used to punch 15-mm long strips of skin of 2 mm width whose length was orthogonal to the direction of incision. The tensiometer configuration was modified to expedite tensile measurements on fresh skin, and load-to-failure was measured for each strip of skin from the cephalad to the caudal region. We evaluated sources of error in the animal model and the testing protocol and developed procedures to maximize speed and reproducibility in tensile strength measurements. This report provides guidance for efficient and reproducible tensile strength measurement of large numbers of skin specimens from freshly sacrificed animals.

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Tattoo placement to identify the two ends of the healing incisional wound assisted in decreasing error in the position and orientation of tensile strips.

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Custom-made punches to prepare skin strips for tensile testing helped conduct tensile tests of fresh tissue rapidly.

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Alteration of the manual grips of the tensile tester enabled specimens to be gripped rapidly to significantly accelerate testing for each skin strip.

Amelioration of Head and Neck Radiation-Induced Mucositis and Distant Marrow Suppression in Fanca-/- and Fancg-/- Mice by Intraoral Administration of GS-Nitroxide (JP4-039)

Squamous cell carcinomas of the head and neck are appearing with increased frequency in both marrow transplanted and non-transplanted Fanconi anemia (FA) patients. FA patients commonly display radiosensitivity of epithelial tissues, complicating effective radiotherapy. Fancd2^-/- mice (C57BL/6J and 129/Sv background) demonstrate epithelial tissue sensitivity to single-fraction or fractionated irradiation to the head and neck and distant marrow suppression (abscopal effect), both ameliorated by intraoral administration of the mitochondrial-targeted antioxidant, GS-nitroxide, JP4-039. We now report that mice of two other FA genotypes, Fancg^-/- (B6) and the most prevalent human genotype Fanca^-/- (129/Sv), also demonstrate: 1. reduced longevity of hematopoiesis in long-term bone marrow cultures; 2. radiosensitivity of bone marrow stromal cell lines; and 3. head and neck radiation-induced severe mucositis and abscopal suppression of distant marrow hematopoiesis. Intraoral administration of JP4-039/F15, but not non-mitochondrial-targeted 4-amino-Tempo/F15 or F15 alone, prior to each radiation treatment ameliorated both local and abscopal radiation effects. Head and neck irradiated TGF-β-resistant SMAD3^-/- (129/Sv) mice and double-knockout SMAD3^-/- Fancd2^-/- (129/Sv) mice treated daily with TGF-β receptor antagonist, LY364947, still displayed abscopal bone marrow suppression, implicating a non-TGF-β mechanism. Thus, amelioration of both local normal tissue radiosensitivity and distant marrow suppression by intraoral administration of JP4-039 in Fancg^-/- and Fanca^-/- mice supports a clinical trial of this locally administered normal tissue radioprotector and mitigator during head and neck irradiation in FA patients.

Induction of TGF-β by Irradiation or Chemotherapy in Fanconi Anemia (FA) Mouse Bone Marrow Is Modulated by Small Molecule Radiation Mitigators JP4-039 and MMS350

BACKGROUND/AIM

Total-body irradiation and/or administration of chemotherapy drugs in bone marrow transplantation induce cytokines that can suppress engraftment. Fanconi Anemia (FA) patients have a hyperactive responsiveness to the inhibitory cytokine, transforming growth factor-beta (TGF-β). Small molecule radiation mitigator drugs, JP4-039 and MMS350, were evaluated for suppression of irradiation or drug-induced TGF-β.

MATERIALS AND METHODS

In vivo induction of TGF-β by total-body ionizing irradiation (TBI), L-phenylalanine mustard (L-PAM), busulfan or fludarabine, was quantified. In parallel, mitigator drug amelioration of TGF-β induction in FA D2^-/- (FANCD2^-/-) mouse bone marrow, was studied in vitro. Tissue culture medium, cell lysates, and mouse plasma were analyzed for TGF-β levels.

RESULTS

Induction of TGF-β levels in FANCD2^-/- and FANCD2^+/+ mice and in mouse bone marrow were modulated by both JP4-039 and MMS350.

CONCLUSION

Bone marrow transplantation in FA recipients may benefit from administration of small molecule agents that suppress TGF-β induction.

Reduced Competitive Repopulation Capacity of Multipotential Hematopoietic Stem Cells in the Bone Marrow of Friend Virus-infected Fv2-resistant Mice

BACKGROUND/AIM

The polycythemia form of Friend leukemia virus (FVP) causes splenomegaly and lethal erythroleukemia in Fv-2^s-susceptible mouse strains. We sought to determine whether the hematopoietic stem cell (HSC) pool was expanded in Fv-2^r-resistant mice.

MATERIALS AND METHODS

The 120-day bone marrow transplantation competitive repopulation assay was used to determine whether FVP-infected Fv-2^r C57BL/6 mice demonstrated expansion of the HSC pool compared to the pool of committed hematopoietic progenitor cells in the same marrow assayed in vitro.

RESULTS

There was a significant expansion of committed hematopoietic progenitors observed in virus-infected Fv-2^s FVB mice, but not Fv-2^r C57BL/6 mice. Furthermore, Fv-2^r mice showed no detectable expansion of either committed hematopoietic progenitor cells or the multipotential stem cell pool by competitive repopulation assay.

CONCLUSION

Friend virus disease in Fv-2^s mice is associated with expansion of committed hematopoietic progenitors. Fv-2^r mice show no expansion of either committed progenitor or pluripotential stem cell numbers.

Effectiveness of Analogs of the GS-Nitroxide, JP4-039, as Total Body Irradiation Mitigators

BACKGROUND/AIM

Mitochondrial-targeted gramicidin S (GS)-nitroxide, JP4-039, has been demonstrated to be a potent radiation mitigator, and safe over a wide dose range. In addition, JP4-039 has organ-specific effectiveness when locally applied.

MATERIALS AND METHODS

We tested the effect of another GS-nitroxide, XJB-5-131, which has more effective mitochondrial localization, and compared these results to those for radiation mitigation against the hematopoietic syndrome, and two analogs of JP4-039, which have the same mitochondrial localization signal, but different chemical payloads: JRS527.084 contains a second nitroxide per molecule, and TK649.030 contains an ester group attached to the nitroxide.

RESULTS

The results demonstrate the superiority of JP4-039 as a systemic radiation mitigator.

CONCLUSION

Structure-activity relationships and bioassays demonstrate that JP4-039 is an optimized small-molecule radiation mitigator.

FANCD2 protects against bone marrow injury from ferroptosis

Bone marrow injury remains a serious concern in traditional cancer treatment. Ferroptosis is an iron- and oxidative-dependent form of regulated cell death that has become part of an emerging strategy for chemotherapy. However, the key regulator of ferroptosis in bone marrow injury remains unknown. Here, we show that Fanconi anemia complementation group D2 (FANCD2), a nuclear protein involved in DNA damage repair, protects against ferroptosis-mediated injury in bone marrow stromal cells (BMSCs). The classical ferroptosis inducer erastin remarkably increased the levels of monoubiquitinated FANCD2, which in turn limited DNA damage in BMSCs. FANCD2-deficient BMSCs were more sensitive to erastin-induced ferroptosis (but not autophagy) than FANCD2 wild-type cells. Knockout of FANCD2 increased ferroptosis-associated biochemical events (e.g., ferrous iron accumulation, glutathione depletion, and malondialdehyde production). Mechanically, FANCD2 regulated genes and/or expression of proteins involved in iron metabolism (e.g., FTH1, TF, TFRC, HAMP, HSPB1, SLC40A1, and STEAP3) and lipid peroxidation (e.g., GPX4). Collectively, these findings indicate that FANCD2 plays a novel role in the negative regulation of ferroptosis. FANCD2 could represent an amenable target for the development of novel anticancer therapies aiming to reduce the side effects of ferroptosis inducers.

Radioresistant human lung adenocarcinoma cells that survived multiple fractions of ionizing radiation are sensitive to HSP90 inhibition

Despite the common usage of radiotherapy for the treatment of NSCLC, outcomes for these cancers when treated with ionizing radiation (IR) are still unsatisfactory. A better understanding of the mechanisms underlying resistance to IR is needed to design approaches to eliminate the radioresistant cells and prevent tumor recurrence and metastases. Using multiple fractions of IR we generated radioresistant cells from T2821 and T2851 human lung adenocarcinoma cells. The radioresistant phenotypes present in T2821/R and T2851/R cells include multiple changes in DNA repair genes and proteins expression, upregulation of EMT markers, alterations of cell cycle distribution, upregulation of PI3K/AKT signaling and elevated production of growth factors, cytokines, important for lung cancer progression, such as IL-6, PDGFB and SDF-1 (CXCL12). In addition to being radioresistant these cells were also found to be resistant to cisplatin.

HSP90 is a molecular chaperone involved in stabilization and function of multiple client proteins implicated in NSCLC cell survival and radioresistance. We examined the effect of ganetespib, a novel HSP90 inhibitor, on T2821/R and T2851/R cell survival, migration and radioresistance. Our data indicates that ganetespib has cytotoxic activity against parental T2821 and T2851 cells and radioresistant T2821/R and T2851/R lung tumor cells. Ganetespib does not affect proliferation of normal human lung fibroblasts. Combining IR with ganetespib completely abrogates clonogenic survival of radioresistant cells.

Our data show that HSP90 inhibition can potentiate the effect of radiotherapy and eliminate radioresistant and cisplatin -resistant residual cells, thus it may aid in reducing NSCLC tumor recurrence after fractionated radiotherapy.

A Topical Mitochondria-Targeted Redox-Cycling Nitroxide Mitigates Oxidative Stress-Induced Skin Damage

Skin is the largest human organ, and it provides a first line of defense that includes physical, chemical, and immune mechanisms to combat environmental stress. Radiation is a prevalent environmental stressor. Radiation-induced skin damage ranges from photoaging and cutaneous carcinogenesis caused by UV exposure, to treatment-limiting radiation dermatitis associated with radiotherapy, to cutaneous radiation syndrome, a frequently fatal consequence of exposures from nuclear accidents. The major mechanism of skin injury common to these exposures is radiation-induced oxidative stress. Efforts to prevent or mitigate radiation damage have included development of antioxidants capable of reducing reactive oxygen species. Mitochondria are particularly susceptible to oxidative stress, and mitochondrial-dependent apoptosis plays a major role in radiation-induced tissue damage. We reasoned that targeting a redox cycling nitroxide to mitochondria could prevent reactive oxygen species accumulation, limiting downstream oxidative damage and preserving mitochondrial function. Here we show that in both mouse and human skin, topical application of a mitochondrially targeted antioxidant prevents and mitigates radiation-induced skin damage characterized by clinical dermatitis, loss of barrier function, inflammation, and fibrosis. Further, damage mitigation is associated with reduced apoptosis, preservation of the skin's antioxidant capacity, and reduction of irreversible DNA and protein oxidation associated with oxidative stress.

Evolution of malignant plasmacytoma cell lines from K14E7 Fancd2-/- mouse long-term bone marrow cultures

We tested the effect of expression of the Human Papilloma Virus (HPV E7) oncogene on hematopoiesis in long-term bone marrow cultures (LTBMCs) derived from K14E7 (FVB) Fancd2-/- (129/Sv), K14E7 Fancd2+/+, Fancd2-/-, and control (FVB X 129/Sv) Fl mice. K14E7 Fancd2-/- and Fancd2-/- LTBMCs showed decreased duration of production of total nonadherent hematopoietic cells and progenitors forming day 7 and day 14 multilineage CFU-GEMM colonies in secondary cultures (7 wks and 8 wks respectively) compared to cultures from K14E7 Fancd2+/+ (17 wks) or control mice (18 wks) p < 0.0001. Marrow stromal cell lines derived from both K14E7 Fancd2-/- and Fancd2-/- cultures were radiosensitive, as were IL-3 dependent hematopoietic progenitor cell lines derived from K14E7 Fancd2-/- cultures. In contrast, Fancd2-/- mouse hematopoietic progenitor cell lines and fresh marrow were radioresistant. K14E7 Fancd2-/- mouse freshly explanted bone marrow expressed no detectable K14 or E7; however, LTBMCs produced K14 positive factor-independent (FI) clonal malignant plasmacytoma forming cell lines in which E7 was detected in the nucleus with p53 and Rb. Transfection of an E6/E7 plasmid into Fancd2-/-, but not control Fancd2+/+ IL-3 dependent hematopoietic progenitor cell lines, increased cloning efficiency, cell growth, and induced malignant cell lines. Therefore, the altered radiobiology of hematopoietic progenitor cells and malignant transformation in vitro by K14E7 expression in cells of the Fancd2-/- genotype suggests a potential role of HPV in hematopoietic malignancies in FA patients.

Abstract 1660: JP4-039/F14 treatment of E13 pregnant mice 24 hours after total body irradiation (TBI) improves survival, growth and development of fetal mice

Purpose: A practical radiation mitigator must be safe in pregnant females. Irradiation during pregnancy can induce fetal death, stunt growth, and/or lead to teratogenic and carcinogenic effects dependent on stage of gestation. We evaluated the mitochondrial targeted GS-nitroxide mitigator JP4-039 for effects on total body irradiated (TBI) pregnant mice.

Methods: Timed pregnant C57Bl/6NHsd mice at E13 were irradiated to 3 Gy, subgroups were injected IV 24 hr later (E14) with JP4-039 in F14 emulsion (4 ug JP4-039 in 100 ul of F14). Mice were followed for number of pups born, weight of pups at day 5 after birth, and for number of survivors at time of weaning. In other studies of irradiation effects, new- born pups, on the day of delivery, were euthanized, fixed, sectioned and examined microscopically.

Results: Nonirradiated mice showed 97 ± 2% of newborn surviving until weaning. Pups born to 3 Gy irradiated E13 pregnant mice had decreased survival (8.3 ± 8.7%) (p &lt; 0.0001). Control nonirradiated pregnant mice receiving JP4-039/F14 or F14 alone showed no effect on pup survival (85 ± 10% at weaning) (p = 0.1453). The survival of pups from 3 Gy irradiated E13 pregnant mice that received JP4-039/F14 24 hr after irradiation was significantly decreased (45 ± 16.4% compared to nonirradiated controls (p = 0.0230). All newborn pups were weighed at 5 days after birth: those surviving 3 Gy in utero had significantly decreased weight of 1.64 ± 0.04 g compared to 2.73 ± 0.08 g for nonirradiated controls (p &lt; 0.0001). In contrast, while the 3 Gy TBI E13 irradiated pups from mothers that received JP4-039/F14 showed no significant weight change compared to control nonirradiated pups (2.44 ± 0.15 and 2.73 ± 0.08, respectively, p = 0.0799). Their weight was significantly increased compared to the 3 Gy irradiated group (2.44 ± 0.15 and 1.64 ± 0.04 g, respectively, p = 0.0433). Pups from nonirradiated mothers that were administered JP4-039/F14 had a significantly increased weight on day 5 compared to nonirradiated mice (3.32 ± 0.10 and 2.73 ± 0.08 g, respectively, p &lt; 0.0001). Microscopic examination of irradiated pups dying at day of birth, revealed: 1) increased number of hematopoietic precursors in liver and decreased glycogen stores in the hepatocytes; 2)adrenal glands were enlarged and contain severely hypertrophied cortical cells; 3) brain, showed necrosis and loss of parenchyma within the intermediate zone of white matter and cell debris in the lateral ventricles. These changes were not observed in pups from JP4-039/F14 treated mothers, sacrificed on the day of birth.

Conclusions: Treatment of total body irradiated E13 pregnant mice at E14 with JP4-039/F14 was safe and effective as a radiation mitigator, led to increased numbers of surviving newborns, improved growth and development, and after weaning over 21 days, and increased body weight with no late deaths.

Supported by NIAID/NIH U19-AI068021

Citation Format: Michael W. Epperly, Lora Rigatti, Tracy Dixon, Song Li, Joel S. Greenberger. JP4-039/F14 treatment of E13 pregnant mice 24 hours after total body irradiation (TBI) improves survival, growth and development of fetal mice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1660.