UCLA Cores: UCLA Center for Medical Countermeasures against Radiation Components

Drs. William McBride, Joanne Weidhaas & John Chute: Administrative Core

The Administrative Core will continue to promote interactions with other CMCRs and members of the Consortium, with NIAID Program leaders, and with industry, working to further the CMCR goals. At the local level, we will continue to use Internal and the External Scientific Review Groups (ISAG/ESAG) to develop new avenues of research and to build a strong an infrastructure at UCLA to continue to discover and develop novel mitigators.

Dr. Julian Whitelegge: Product Development Core

The Product Development Core (PDC) within the UCLA-CMCR Program has developed an effective infrastructure for the discovery and development of novel mitigators. With time this Core has evolved away from high throughput screening for projects to perform more chemoinformatics, drug synthesis and optimization, and pharmacokinetics. In acknowledgement of its evolving role, it has been renamed the Product Development Core (PDC). It will retain many of its functions in drug discovery, but has repositioned itself with added expertise to perform more pharmaceutical chemistry and organic synthesis; chemoinformatics and drug optimization; high-throughput assay development for toxicology, mechanism-of-action (MOA) and biomarker screening; pharmacokinetics mass spectrometry; pharmacodynamics and absorption, distribution, metabolism and excretion (ADME) mass spectrometry; deep sequencing and transcriptomics informatics; and biomarker mass spectrometry.

Dr. Kei Iwamoto: Product Testing Animal Core

The Product Testing Animal Core (PTAC) provides: 1) high-quality gnotobiotic mice, 2) in vivo evaluation of radiomitigators, 3) axenic models of radiation effects, and 4) support regarding animal research issues and regulations. The PTAC’s platforms are exceptional because it manages, breeds, and maintains its own mouse colony. For over 30 years, the vivarium has been maintained as an extremely high-quality gnotobiotic facility where animals have a defined microbiota. Performing experiments in mice that are of the highest quality from microbial and genetic standpoints is essential if meaningful results are to be obtained. Further, establishment of an absolutely germfree, or axenic, mouse colony within the gnotobiotic facility has been initiated and the PTAC plans to expand it to accommodate the needs of the CMCR. Germfree animals will facilitate the CMCR mission by eliminating a role for microbes in ARS and delayed effects of acute radiation exposure. The facility currently breeds over 140 strains, 59,000 per year, of normal, immune deficient, and transgenic mice all of which are accessible to CMCR investigators. As part of the pipeline for new drug development, the PTAC, utilizing such in-house animal models, will characterize the pharmacokinetics and examine the radiomitigative efficacy of compounds screened from the Product Development Core (PDC). This includes the effects of ionizing radiation on multiple normal tissues (bone marrow, intestine, lung, skin, kidney, brain, and spinal cord) at the molecular, cellular, and whole tissue level. Finally, like all facilities at UCLA, the PTAC-associated colony is fully AAALAC-accredited. The PTAC will perform a vital function in facilitating animal research within the CMCR, integrating the Projects, standardizing information derived from individual studies, and enabling development of viable new drugs for imminent future clinical investigation to meet the CMCR mission.

Consortium Core Led By UCLA

Dr. Ke Sheng: Radiation Physics Core

Led by Dr. Ke Sheng in the Department of Radiation Oncology, The RPC will be responsible for providing consortium-wide standards for the various research sites and sources used to conduct studies on irradiated animals to ensure that all such work conducted within the CMCRC is performed under standardized methodologies. Specifically the RPC will be responsible for:

  1. Education. Since most operators of the small animal irradiator are not medical physicists and do not have previous training in dosimetry, it is imperative for them to understand the factors contributing to inaccurate dosimetry and be able to follow the standard quality assurance protocols designated by the RPC. The RPC will provide remote and online seminars to disseminate such information and be available for individual question and answers.
  2. Establish SOPs and QA Procedures. The RPC will develop cost effective QA procedures that can be performed by individuals with minimal equipment and training at each participating center with remote RPC technical support.
  3. Service. The RPC will provide onsite initial QA for each machine that will be used for the consortium. We will establish a baseline for subsequent annual and monthly QA that will be performed by onsite personnel. We will provide consultation services for special physics dosimetry that cannot be achieved using open field radiation. 

UCLA Projects

The UCLA-CMCR focuses on three interdisciplinary projects involving investigators in the departments of Microbiology, Immunology & Molecular Genetics, Hematology-Oncology, and Radiation Oncology.

Dr. Genhong Cheng: Acute and Long Term Immune Responses to Radiation and Mitigation

The goal of this project is to understand the role of immune responses in and the mechanisms responsible for the short and long term diseases caused by exposure to sources of ionizing radiation. One important aspect of radiation injury is the release of both endogenous damage associated molecular patterns (DAMPs) from the damaged tissues and pathogen associated molecular patterns (PAMPs) from the gastrointestinal system. Based on our results from multiple tissue damage models, we have recently hypothesized that over reactive innate immune responses to DAMPs and PAMPs released after irradiation can further trigger secondary tissue damages by proinflammatory cytokines and autoantibodies. We have further developed a widely available and easily deliverable DAMP blocking compound, glycyrrhizic acid (GA), as a potent radiation mitigator. In addition, while GCSF has been used as a standard mitigator, we have developed a bivalent GCSF (Bi-GCSF) as a more potent and stable radiation mitigator. Overall, this project will evaluate the effects of individual mitigators on the short and long term innate and adaptive immune systems and further develop a combination of mitigators that can effectively treat both acute and chronic diseases after radiation.

Dr. John Chute: Protein Tyrosine Phosphatase-Sigma, A Novel Target for Mitigation of Acute Radiation Injury

The potentially devastating effects of acute radiation exposure on the hematopoietic, gastrointestinal and other vital organs are well chronicled, but few effective mitigators exist which are capable of ameliorating radiation-induced vital organ damage. The Chute laboratory has discovered that cells within the bone marrow (BM) microenvironment, specifically vascular endothelial cells (ECs), secrete growth factors capable of promoting hematopoietic stem cell (HSC) regeneration following radiation injury. They showed further that 2 EC-derived proteins, pleiotrophin (PTN) and epidermal growth factor (EGF), produced marked improvements in mice survival when administered after lethal dose irradiation. PTN treatment significantly improved the survival of irradiated mice when administered as late as 4 days after radiation exposure, highlighting the practical utility of PTN as a deliverable mitigator of radiation injury. Based on our discovery that PTN promotes HSC regeneration via inhibition of protein tyrosine phosphatase receptor – zeta (PTPζ), we screened HSCs for expression of other members of the PTP receptor family. We found that PTP-Sigma (PTPσ) was more than 100-fold overexpressed compared to PTPζ on BM HSCs. Interestingly, HSCs from PTPσ-/- mice displayed 8-fold increased long term repopulating capacity compared to HSCs from PTPσ+/+ mice and loss-of-function studies suggested that this was mediated by the RhoGTPase, Rac1. Importantly, PTPσ-/- mice displayed significantly increased recovery of BM colony forming cells (CFCs) at day +10 following 600 cGy total body irradiation (TBI) compared to identically irradiated PTPσ+/+ mice. Based upon these preliminary data, we hypothesize that PTPσ regulates HSC regeneration following irradiation and that inhibition of PTPσ will promote HSC regeneration and improve survival following radiation injury. The broad objective of this project is to interrogate PTPσ and Rac proteins as novel targets for radiation mitigation and to develop a PTPσ- or Rac-targeted therapeutic for victims of radiation injury and for dual use to accelerate hematopoietic reconstitution in myelosuppressed or myeloablated patients.

Dr. Frank Pajonk: Radiation Mitigation and Normal Tissue Stem Cells

The long-term goal of this research project is to identify mechanisms by which normal tissue stem cells that initially survive exposure to radiation are expanded in vivo to maintain tissue integrity. The goal of this proposal is to uncover the mechanism of mitigation observed with drugs, especially those containing 4-nitrosulfonylpiperazine active groups. We will investigate whether the reconstitution of the normal tissue stem cell pool seen after application of these mitigators is a direct effect on the stem cell populations in the gut and central nervous system (CNS), or mediated by providing a microenvironment permissive for stem cell expansion. Using in vitro and in vivo model systems for acute and late radiation damage we will investigate direct and indirect effects of these drugs on stem cell expansion and plasticity and uncover the underlying signaling events that lead to radiation mitigation. Specifically, we hypothesize that radiation mitigators with 4-nitrosulfonylpiperazine groups, identified in the previous funding period, affect normal tissue stem cell populations in the gut and CNS directly or indirectly through G-protein-coupled receptor-mediated signaling. The systematic study of the cellular effects of mitigators discovered at UCLA in mitigating ARS and DEARE, and uncovering the underlying mechanisms will lay ground for finding and understanding novel dual function mitigators for acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE). This will have a wide impact on the field, as it will uncover common targets on normal tissue stem cells that can be used to mitigate radiation damage on multiple organ systems simultaneously.