Development Of Medical Countermeasures Research Articles

Crimean Congo Hemorrhagic Fever Virus for Clinicians-Virology, Pathogenesis, and Pathology.

Crimean-Congo hemorrhagic fever (CCHF), caused by CCHF virus, is a tickborne disease that can cause a range of illness outcomes, from asymptomatic infection to fatal viral hemorrhagic fever; the disease has been described in >30 countries. We conducted a literature review to provide an overview of the virology, pathogenesis, and pathology of CCHF for clinicians. The virus life cycle and molecular interactions are complex and not fully described. Although pathogenesis and immunobiology are not yet fully understood, it is clear that multiple processes contribute to viral entry, replication, and pathological damage. Limited autopsy reports describe multiorgan involvement with extravasation and hemorrhages. Advanced understanding of CCHF virus pathogenesis and immunology will improve patient care and accelerate the development of medical countermeasures for CCHF.

Gastrointestinal Acute Radiation Syndrome: Mechanisms, Models, Markers, and Medical Countermeasures.

There have been a number of reported human exposures to high dose radiation, resulting from accidents at nuclear power plants (e.g., Chernobyl), atomic bombings (Hiroshima and Nagasaki), and mishaps in industrial and medical settings. If absorbed radiation doses are high enough, evolution of acute radiation syndromes (ARS) will likely impact both the bone marrow as well as the gastrointestinal (GI) tract. Damage incurred in the latter can lead to nutrient malabsorption, dehydration, electrolyte imbalance, altered microbiome and metabolites, and impaired barrier function, which can lead to septicemia and death. To prepare for a medical response should such an incident arise, the National Institute of Allergy and Infectious Diseases (NIAID) funds basic and translational research to address radiation-induced GI-ARS, which remains a critical and prioritized unmet need. Areas of interest include identification of targets for damage and mitigation, animal model development, and testing of medical countermeasures (MCMs) to address GI complications resulting from radiation exposure. To appropriately model expected human responses, it is helpful to study analogous disease states in the clinic that resemble GI-ARS, to inform on best practices for diagnosis and treatment, and translate them back to inform nonclinical drug efficacy models. For these reasons, the NIAID partnered with two other U.S. government agencies (the Biomedical Advanced Research and Development Authority, and the Food and Drug Administration), to explore models, biomarkers, and diagnostics to improve understanding of the complexities of GI-ARS and investigate promising treatment approaches. A two-day workshop was convened in August 2022 that comprised presentations from academia, industry, healthcare, and government, and highlighted talks from 26 subject matter experts across five scientific sessions. This report provides an overview of information that was presented during the conference, and important discussions surrounding a broad range of topics that are critical for the research, development, licensure, and use of MCMs for GI-ARS.

Ebola virus disease sequelae and viral persistence in animal models: Implications for the future.

Ebola virus disease (EVD), caused by infection with Ebola virus, results in severe, acute illness with a high mortality rate. As the incidence of outbreaks of EVD increases and with the development and approval of medical countermeasures (MCMs) against the acute disease, late phases of EVD, including sequelae, recrudescence, and viral persistence, are occuring more frequently and are now a focus of ongoing research. Existing animal disease models recapitulate acute EVD but are not suitable to investigate the mechanisms of these late disease phenomena. Although there are challenges in establishing such a late disease model, the filovirus research community has begun to call for the development of an EBOV persistence model to address late disease concerns. Ultimately, this will aid the development of MCMs against late disease and benefit survivors of future EVD and filovirus outbreaks.

Delayed effects of radiation exposure in a C57L/J mouse model of partial body irradiation with ~2.5% bone marrow shielding.

Mouse models of radiation injury are critical to the development of medical countermeasures (MCMs) against radiation. Now that MCMs against hematopoietic acute radiation syndrome (H-ARS) have achieved regulatory approval, attention is shifting to develop MCMs against the adverse effects of gastrointestinal acute radiation syndrome (GI-ARS) and delayed effects of acute radiation exposure (DEARE). The C57L/J mouse model of partial body irradiation (PBI) with 2.5% bone marrow shielding (BM2.5) is being leveraged to examine both GI-ARS and DEARE effects. Within days of PBI, mice may develop H- and GI-ARS followed several months later by DEARE as a multi-organ injury, which typically involves the lung and kidney (L- and K-DEARE, respectively). The objective of this manuscript is to describe the dose response relationship and progression of radiation injury in the C57L/J mouse and to evaluate its suitability for use in DEARE MCM testing. In two separate studies conducted over 2 years, male and female C57L/J mice were exposed to PBI BM2.5 with one hindlimb shielded from radiation, representing ~2.5% bone marrow shielding/sparing. Mice were X-ray irradiated at doses ranging from 9 to 13 Gy at 10 to 12 weeks of age for the purposes of assessing ARS survival at 30 days and DEARE survival at 182 days post-irradiation. Clinical indicators of ARS and DEARE were determined by clinical observations, body weights, hematology, clinical chemistry, magnetic resonance imaging (MRI) of lung, and histopathology of selected tissues. C57L/J mice developed canonical ARS responses of hematopoietic atrophy and gastrointestinal injury resulting in dose dependent mortality at doses ≥11 Gy between 1- and 15-days post-irradiation. In animals that survived ARS, DEARE associated mortality occurred in dose dependent fashion at ≥9 Gy for both sexes between 60- and 159-days post-irradiation with histopathology examinations indicating lung injury as the primary cause of death in moribund animals. The PBI BM2.5 C57L/J mouse model reliably produced known H- and GI-ARS effects at doses greater than those resulting in DEARE effects. Because of this, the C57L/J mouse can be used to test MCMs against L-DEARE injury, while avoiding ARS associated mortality.

Product Development within the National Institutes of Health Radiation and Nuclear Countermeasures Program.

The Radiation and Nuclear Countermeasures Program (RNCP) at the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH) was established to facilitate the development of medical countermeasures (MCMs) and diagnostic approaches for use in a radiation public health emergency. Approvals for MCMs can be very challenging but are made possible under the United States Food and Drug Administration (FDA) Animal Rule, which is designed to enable licensure of drugs or biologics when clinical efficacy studies are unethical or unfeasible. The NIAID portfolio includes grants, contracts, and inter-agency agreements designed to span all aspects of drug development and encompasses basic research through FDA approval. In addition, NIAID manages an active portfolio of biodosimetry approaches to assess injuries and absorbed radiation levels to guide triage and treatment decisions. NIAID, together with grantees, contractors, and other stakeholders with promising products, works to advance candidate MCMs and biodosimetry tools through an established product development pipeline. In addition to managing grants and contracts, NIAID tests promising candidates in our established preclinical animal models, and the NIAID Program Officers work closely with sponsors as product managers to guide them through the process. In addition, a valuable benefit for stakeholders is working with the NIAID Office of Regulatory Affairs, where NIAID coordinates with the FDA to facilitate interactions between sponsors and the agency. Activities funded by NIAID include basic research (e.g., library screens to discover new products, determine early efficacy, and delineate mechanism of action) and the development of small and large animal models of radiation-induced hematopoietic, gastrointestinal, lung, kidney, and skin injury, radiation combined injury, and radionuclide decorporation. NIAID also sponsors Good Laboratory Practice product safety, pharmacokinetic, pharmacodynamic, and toxicology studies, as well as efficacy and dose-ranging studies to optimize product regimens. For later-stage candidates, NIAID funds large-scale manufacturing and formulation development of products. The program also supports Phase 1 human clinical studies to ensure human safety and to bridge pharmacokinetic, pharmacodynamic, and efficacy data from animals to humans. To date, NIAID has supported >900 animal studies and one clinical study, evaluating >500 new/repurposed radiation MCMs and biodosimetric approaches. NIAID sponsorship led to the approval of three of the six drugs for acute radiation syndrome under the FDA Animal Rule, five Investigational New Drug applications, and 18 additional submissions for Investigational Device Exemptions, while advancing 38 projects to the Biomedical Advanced Research and Development Authority for follow-on research and development.

How Global Collaboration Can Improve the Medical Countermeasure Life Cycle for Infectious Disease Outbreaks: A BARDA Perspective.

Infectious disease outbreaks have become increasingly common and require global partnership for adequate preparedness and response. During outbreaks, medical countermeasures (MCMs)-vaccines, therapeutics, and diagnostics-need to reach patients quickly. BARDA utilizes public-private partnerships to support advanced development of MCMs through U.S. FDA approval against a variety of threats within its mission space. MCM preparedness and response must be approached as an integrated life cycle, not as independent steps. Recent filovirus outbreaks in Africa exemplify that collaborative relationships are critical for emergency response, and products with regulatory approval can expand access and reach patients quicker than investigational products. Unfortunately, insufficient funding globally and differences in funders' prioritization puts gains and future efforts at risk. Of primary concern is a) lack of a feasible regulatory path and clinical capability to achieve regulatory approval for new MCMs for many diseases; and b) the need for partners with the mandate, funding, and capabilities to support the life cycle activities following development-long-term sustainment of manufacturing capability and stockpiling of licensed products to support international outbreaks. Finding partners that complement BARDA's mission and support the MCM life cycle will be a key component in deciding which MCM development efforts can be supported. Without collaboration, the global community runs the risk of losing the capabilities built through years of investment and being underprepared to combat future threats. Synergies between funders that have different roles and responsibilities within the MCM life cycle are critical to MCM availability and create long-term sustainment of products to ensure access.

Host microbiome depletion attenuates biofluid metabolite responses following radiation exposure.

Development of novel biodosimetry assays and medical countermeasures is needed to obtain a level of radiation preparedness in the event of malicious or accidental mass exposures to ionizing radiation (IR). For biodosimetry, metabolic profiling with mass spectrometry (MS) platforms has identified several small molecules in easily accessible biofluids that are promising for dose reconstruction. As our microbiome has profound effects on biofluid metabolite composition, it is of interest how variation in the host microbiome may affect metabolomics based biodosimetry. Here, we 'knocked out' the microbiome of male and female C57BL/6 mice (Abx mice) using antibiotics and then irradiated (0, 3, or 8 Gy) them to determine the role of the host microbiome on biofluid radiation signatures (1 and 3 d urine, 3 d serum). Biofluid metabolite levels were compared to a sham and irradiated group of mice with a normal microbiome (Abx-con mice). To compare post-irradiation effects in urine, we calculated the Spearman's correlation coefficients of metabolite levels with radiation dose. For selected metabolites of interest, we performed more detailed analyses using linear mixed effect models to determine the effects of radiation dose, time, and microbiome depletion. Serum metabolite levels were compared using an ANOVA. Several metabolites were affected after antibiotic administration in the tryptophan and amino acid pathways, sterol hormone, xenobiotic and bile acid pathways (urine) and lipid metabolism (serum), with a post-irradiation attenuative effect observed for Abx mice. In urine, dose×time interactions were supported for a defined radiation metabolite panel (carnitine, hexosamine-valine-isoleucine [Hex-V-I], creatine, citric acid, and Nε,Nε,Nε-trimethyllysine [TML]) and dose for N1-acetylspermidine, which also provided excellent (AUROC ≥ 0.90) to good (AUROC ≥ 0.80) sensitivity and specificity according to the area under the receiver operator characteristic curve (AUROC) analysis. In serum, a panel consisting of carnitine, citric acid, lysophosphatidylcholine (LysoPC) (14:0), LysoPC (20:3), and LysoPC (22:5) also gave excellent to good sensitivity and specificity for identifying post-irradiated individuals at 3 d. Although the microbiome affected the basal levels and/or post-irradiation levels of these metabolites, their utility in dose reconstruction irrespective of microbiome status is encouraging for the use of metabolomics as a novel biodosimetry assay.

Pharmacokinetics and Biodistribution of 16,16 dimethyl Prostaglandin E2 in Non-Irradiated and Irradiated Mice and Non-Irradiated Non-Human Primates.

Exposure to high-dose ionizing radiation can lead to life-threatening injuries and mortality. Bone marrow is the most sensitive organ to radiation damage, resulting in the hematopoietic acute radiation syndrome (H-ARS) with the potential sequelae of infection, hemorrhage, anemia, and death if untreated. The development of medical countermeasures (MCMs) to protect or mitigate radiation injury is a medical necessity. In our well-established murine model of H-ARS we have demonstrated that the prostaglandin E2 (PGE2) analog 16,16 dimethyl-PGE2 (dmPGE2) has survival efficacy as both a radioprotectant and radiomitigator. The purpose of this study was to investigate the pharmacokinetics (PK) and biodistribution of dmPGE2 when used as a radioprotector in irradiated and non-irradiated inbred C57BL/6J mice, PK in irradiated and non-irradiated Jackson Diversity Outbred (JDO) mice, and the PK profile of dmPGE2 in non-irradiated non-human primates (NHPs). The C57BL/6J and JDO mice each received a single subcutaneous (SC) dose of 35 ug of dmPGE2 and were randomized to either receive radiation 30 min later or remain non-irradiated. Plasma and tissue PK profiles were established. The NHP were dosed with 0.1 mg/kg by SC administration and the PK profile in plasma was established. The concentration time profiles were analyzed by standard non-compartmental analysis and the metrics of AUC0-Inf, AUC60-480 (AUC from 60-480 min), Cmax, and t1/2 were evaluated. AUC60-480 represents the postirradiation time frame and was used to assess radiation effect. Overall, AUC0-Inf, Cmax, and t1/2 were numerically similar between strains (C57BL/6J and JDO) when combined, regardless of exposure status (AUC0-Inf: 112.50 ng·h/ml and 114.48 ng·h/ml, Cmax: 44.53 ng/ml and 63.96 ng/ml; t1/2: 1.8 h and 1.1 h, respectively). PK metrics were numerically lower in irradiated C57BL/6J mice than in non-irradiated mice [irradiation ratio: irradiated values/non-irradiated values = 0.71 for AUC60-480 (i.e., 29% lower), and 0.6 for t1/2]. In JDO mice, the radiation ratio was 0.53 for AUC60-480 (i.e., 47% lower), and 1.7 h for t1/2. The AUC0-Inf, Cmax, and t1/2 of the NHPs were 29.20 ng·h/ml, 7.68 ng/ml, and 3.26 h, respectively. Despite the numerical differences seen between irradiated and non-irradiated groups in PK parameters, the effect of radiation on PK can be considered minimal based on current data. The biodistribution in C57BL/6J mice showed that dmPGE2 per gram of tissue was highest in the lungs, regardless of exposure status. The radiation ratio for the different tissue AUC60-480 in C57BL/6J mice ranged between 0.5-1.1 (50% lower to 10% higher). Spleen, liver and bone marrow showed close to twice lower exposures after irradiation, whereas heart had a 10% higher exposure. Based on the clearance values from mice and NHP, the estimated allometric scaling coefficient was 0.81 (95% CI: 0.75, 0.86). While slightly higher than the current literature estimates of 0.75, this scaling coefficient can be considered a reasonable estimate and can be used to scale dmPGE2 dosing from animals to humans for future trials.

Animal Model Considerations for Medical Countermeasure Development for Radiation and Sulfur Mustard Exposures: Animal models for radiation and HD exposures.

Development of medical countermeasures (MCM) to mitigate and/ or treat the pulmonary complications associated with exposure to chemical, radiological, and/ or nuclear weapons is a national, public health preparedness posture priority in the United States (US). Pulmonary exposure to either sulfur mustard vapor or radiation causes oxidative damage, vascular injury, hyperinflammation, and pro-fibrotic signaling cascades that lead to life-threatening and potentially debilitating lung disease. There is no MCM currently approved by the US Food and Drug Administration (FDA) to mitigate and/ or treat lung injury caused by sulfur mustard or radiation exposure. Thus, there remains a major unmet public health need for development of threat-agnostic, host-directed therapeutics that target common pathophysiological mechanisms underlying the progression of acute and/ or late lung injury independent of the etiology of disease. This review describes the clinical manifestations and underlying mechanisms of sulfur mustard and radiation-induced lung injury and regulatory considerations for MCM development under the non-traditional Animal Rule pathway.

The Arenaviridae Family: Knowledge Gaps, Animal Models, Countermeasures, and Prototype Pathogens.

Lassa virus (LASV), Junin virus (JUNV), and several other members of the Arenaviridae family are capable of zoonotic transfer to humans and induction of severe viral hemorrhagic fevers. Despite the importance of arenaviruses as potential pandemic pathogens, numerous gaps exist in scientific knowledge pertaining to this diverse family, including gaps in understanding replication, immunosuppression, receptor usage, and elicitation of neutralizing antibody responses, that in turn complicates development of medical countermeasures. A further challenge to the development of medical countermeasures for arenaviruses is the requirement for use of animal models at high levels of biocontainment, where each model has distinct advantages and limitations depending on, availability of space, animals species-specific reagents, and most importantly the ability of the model to faithfully recapitulate human disease. Designation of LASV and JUNV as prototype pathogens can facilitate progress in addressing the public health challenges posed by members of this important virus family.

Prototype Pathogens for Vaccine and Monoclonal Antibody Countermeasure Development: NIAID Workshop Process and Outcomes for Viral Families of Pandemic Potential.

Given the increased risk of pandemics driven by emerging and reemerging infectious diseases, it is imperative that the United States and global scientific community be better prepared for future threats by prioritizing and launching key research programs and strategies. In December 2021, the National Institute of Allergy and Infectious Diseases (NIAID) published its pandemic preparedness plan, which focuses on the prototype pathogen approach for medical countermeasure development. The plan was introduced before its release at a NIAID-hosted workshop in November 2021 that featured scientific experts from the extramural community, government, and the private sector and focused on selection of prototype pathogens from 10 viral families with pandemic risk and moderate resources. This article will serve as an introduction to this special issue and will briefly define the prototype pathogen approach, describe the workshop goals and process for outcomes, and provide an outline of the viral working group articles to follow and future directions for NIAID.

Temporal changes in pathology and viral RNA distribution in guinea pigs following separate infection with two New World Arenaviruses.

Numerous arenaviruses have been identified throughout the Americas and a subset of these viruses cause viral hemorrhagic fever in humans. This study compared the pathology and viral RNA distribution in Hartley guinea pigs challenged with two human-disease causing New World arenaviruses, Junin virus (JUNV) or Guanarito virus (GTOV). Histopathologic analysis and RNA in situ hybridization revealed similar pathology and viral RNA distribution for both groups of animals challenged with either JUNV or GTOV on days 3, 7, 10 and 12 post exposure (PE). Gross lesions were first observed on day 7 and primarily involved the lungs and liver. The most severe histologic lesions occurred in the lymph nodes, spleen, and thymus and included lymphoid depletion and necrosis which increased in severity over time. Extensive necrosis was also observed in the bone marrow on day 12. Minimal to mild inflammation with and without necrosis was observed in the choroid plexus of the brain, choroid of the eye, intestinal tract, lung and adrenal gland. Significant liver lesions were rare, consisting predominantly of hepatocyte vacuolation. Viral RNA labeling was identified in nearly all organs examined, was often extensive in certain organs and generally increased over time starting on day 7. Our data demonstrate the guinea pig may serve as a useful model to study New World arenavirus infection in humans and for the evaluation and development of medical countermeasures.

Comparative characterization of Crimean-Congo hemorrhagic fever virus cell culture systems with application to propagation and titration methods

Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV) is a biosafety level 4 and World Health Organization top priority pathogen. Infection leads to an often fatal hemorrhagic fever disease in humans. The tick-borne virus is endemic in countries across Asia, Europe and Africa, with signs of spreading into new regions. Despite the severity of disease and the potential of CCHFV geographic expansion to cause widespread outbreaks, no approved vaccine or treatment is currently available. Critical for basic research and the development of diagnostics or medical countermeasures, CCHFV viral stocks are commonly produced in Vero E6 and SW-13 cell lines. While a variety of in-house methods are being used across different laboratories, there has been no clear, specific consensus on a standard, optimal system for CCHFV growth and titration. In this study, we perform a systematic, side-by-side characterization of Vero E6 and SW-13 cell lines concerning the replication kinetics of CCHFV under different culture conditions. SW-13 cells are typically cultured in a CO2-free condition (SW-13 CO2−) according to the American Type Culture Collection. However, we identify a CO2-compatible culture condition (SW-13 CO2+) that demonstrates the highest viral load (RNA concentration) and titer (infectious virus concentration) in the culture supernatants, in comparison to SW-13 CO2− and Vero E6 cultures. This optimal viral propagation system also leads to the development of two titration methods: an immunostaining-based plaque assay using a commercial CCHFV antibody and a colorimetric readout, and an antibody staining-free, cytopathic effect-based median tissue culture infectious dose assay using a simple excel calculator. These are anticipated to serve as a basis for a reproducible, standardized and user-friendly platform for CCHFV propagation and titration.

Biopharmaceutical Financialization and Public Funding of Medical Countermeasures (MCMs) in Canada During the COVID-19 Pandemic.

Analysing the Canadian government's efforts to support the development of COVID-19 "medical countermeasures" (MCMs), this article seeks insights into political economy as a driver of pandemic response. We explore whether Canadian public funding policy during the pandemic involved departures from established practices of financialisation in biopharmaceutical research and development (R&D), including the dominance of private sector involvement in an intellectual property (IP) intensive approach to innovation underscoring profit, and governance opacity. We interrogate public funding for MCMs by analyzing how much the Government of Canada (GoC) spent, how those funds were allocated, on what terms, and to whom. We identify the funding institutions, and the funds awarded between February 10, 2020, and March 31, 2021, to support the research, development, and manufacturing of MCMs, including diagnostics, vaccines, therapeutics, and information about clinical management and virus transmission. To collect these data, we conducted searches on the Internet, public data repositories, and filed several requests under the Access to Information Act (1985). Subsequently, we carried out a document-based analysis of electronically accessible research contracts, proposals, grant calls, and policy announcements. The GoC announced CAD$ 1.4 billion for research, development and manufacturing of COVID-19 MCMs. Fully 68% (CAD$ 959 million) of the announced public funding was channelled to investment in private sector firms. Canadian public funding showed a consistent focus on early and late stage development of COVID-19 MCMs and the expansion of biopharmaceutical manufacturing capacity. Assessing whether Canada's investments into developing COVID-19 MCMs safeguard affordable and transparent access to the products of publicly funded research, we found that access policies on IP management, sharing of clinical data, affordability and availability were not systematic, consistent, or transparent, and few, if any, mechanisms ensured long-term sustainability. Beyond incremental change in policy goals, such as public investment in domestic biomanufacturing, the features of Canadian public policies endorsing financialization in the biopharmaceutical sector remained largely unchanged during the pandemic.

Radiosensitivity of rhesus nonhuman primates: consideration of sex, supportive care, body weight, and age at time of exposure

ABSTRACT Background Animal models are vital for the development of radiation medical countermeasures for the prophylaxis or treatment of acute radiation syndrome and for the delayed effects of acute radiation exposure. Nonhuman primates (NHPs) play an important role in the regulatory approval of such agents by the United States Food and Drug Administration following the Animal Rule. Reliance on such animal models requires that such models are well characterized. Methods Data gathered from both male and female animals under the same conditions and gathered concurrently are limited; therefore, the authors compared and contrasted here the radiosensitivity of both male and female NHPs provided different levels of clinical support over a range of acute, total-body gamma irradiation, as well as the influence of age and body weight. Results Under matched experimental conditions, the authors observed only marginal, but clearly evident differences between acutely irradiated male and female NHPs relative to the measured response endpoints (rates of survival, blood cell changes, and cytokine fluctuations). These differences appeared to be accentuated by the level of exposure as well as by the nature of clinical support. Conclusion Additional studies with both sexes under various experimental conditions and different radiation qualities run concurrently are needed.

Biological sex differences in renin angiotensin system enzymes ACE and ACE2 regulate normal tissue response to radiation injury.

Introduction: In experimental animal models, biological sex-differences in the manifestation and severity of normal tissue radiation injury have been well-documented. Previously we demonstrated male and female rats have differential and highly reproducible responses to high-dose partial body irradiation (PBI) with male rats having greater susceptibility to both gastrointestinal acute radiation syndrome (GI-ARS) and radiation pneumonitis than female rats. Methods: In the current study, we have investigated whether differential expression of the renin-angiotensin system (RAS) enzymes angiotensin converting enzyme (ACE) and ACE2 contribute to the observed sex-related differences in radiation response. Results: During the period of symptomatic pneumonitis, the relative ratio of ACE to ACE2 (ACE/ACE2) protein in the whole lung was significantly increased by radiation in male rats alone. Systemic treatment with small molecule ACE2 agonist diminazene aceturate (DIZE) increased lung ACE2 activity and reduced morbidity during radiation pneumonitis in both sexes. Notably DIZE treatment also abrogated morbidity in male rats during GI-ARS. We then evaluated the contribution of the irradiated bone marrow (BM) compartment on lung immune cell infiltration and ACE imbalance during pneumonitis. Transplantation of bone marrow from irradiated donors increased both ACE-expressing myeloid cell infiltration and immune ACE activity in the lung during pneumonitis compared to non-irradiated donors. Discussion: Together, these data demonstrate radiation induces a sex-dependent imbalance in the renin-angiotensin system enzymes ACE and ACE2. Additionally, these data suggest a role for ACE-expressing myeloid cells in the pathogenesis of radiation pneumonitis. Finally, the observed sex-differences underscore the need for consideration of sex as a biological variable in the development of medical countermeasures for radiation exposure.

Maintaining Warp Speed: Policy Requirements for a Just-in-Time, Capability-Based, Scalable Medical Countermeasure Research and Development Enterprise.

Maintaining Warp Speed: Policy Requirements for a Just-in-Time, Capability-Based, Scalable Medical Countermeasure Research and Development Enterprise.

722 Select Survey of Human Cadaver Skin Allograft Utilization by 21 Senior Academic Burn Surgeons

Abstract Introduction As of 2022, cryopreserved human cadaver skin allograft remains the gold standard by which all other skin substitutes used for burn care are compared. The 2015 Taiwan Color Dust Explosion burn mass casualty engendered the transfer of emergency tranches of skin allograft from reserves in both the US and EU to Taiwan. HHS/ASPR/BARDA/CBRN led an after-action fact-finding mission to Taiwan and concluded that skin allograft would still play a central role as a safety net in US national burn care preparedness, even as BARDA invested in the development of other burn medical countermeasures that would be part of the preparedness strategy. However, before investments in a skin allograft based national strategy could be built, it was critical that the leaders of the Disaster Committee and Organization and Delivery of Burn Care (ODBC) Committee of the American Burn Association (ABA) commission a survey to verify current practice patterns of senior academic burn surgeons on the use of skin allograft. Methods The committee chairs curated a list of 21 leading academic burn surgeons in North America. These surgeons’ credentials included having been an ABA president, a member of the ABA Board of Trustees, or having chaired a standing committee of the ABA. All 21 surgeons were actively practicing burn care daily. The survey contained 18 questions and was intentionally kept brief (Survey to be provided as Appendix). Results Of the 21 surgeons selected, there was 100% participation and completion of the survey. Most were in practice >15 years (62%) and manage >200 patients surgically per year (71%). The predominant use of allograft is to temporize the wound bed when there are inadequate donor sites (48% “Almost Always”). It is “Often” (48%) used to temporize wound beds prior to autografting. However, most are looking for alternatives to allograft (43% “Sometimes”, 43% “Often”). With ongoing development of skin substitutes, most indicated their allograft use will likely decrease, with only 19% indicating “Probably Not”. Conclusions Human skin allograft continues to play a central role in surgical burn care management. For the foreseeable future, new technologies are not likely to displace allograft use but rather blend with its use. This brief, select survey is not powered but provides a snapshot of the current role of skin allograft. In the future, we may conduct a broader survey to obtain a validated and more granular view of the use of allograft in modern burn care. Applicability of Research to Practice Armed with this information, the US Federal Government acted to increase preparedness after a burn mass casualty. In February 2022, a Request for Proposals for a large vendor-managed inventory of human cryopreserved skin allograft was answered by two separate tissue banks. As of September 2022, $38M was awarded to two partners for procurement and expansion of a vendor managed inventory of cryopreserved human skin allograft to ensure preparedness for rapid response to a burn mass casualty incident.

Ionizing radiation induces lasting changes to the tissue resident memory T cell compartment

Abstract Exposure to sublethal ionizing radiation can occur through various mechanisms, including purposeful medical exposure, nuclear accidents, and acts of nuclear terrorism, making the development of effective medical countermeasures a high public health priority. The induction of DNA damage through reactive oxygen species makes rapidly dividing cells, such as naïve T cells highly sensitive to radiation induced depletion. A previous study demonstrated that broadly, circulating memory T cells are more resistant to numerical loss following radiation exposure compared to naïve T cells. However, the effects of radiation on the more recently described memory T cell subset, tissue resident memory T cells (T RM) remain unknown. T RMhave been identified as a critical T cell subset in protection from a number of infections including influenza, respiratory syncytial virus and malaria. In particular, lung T RMare critical for strain-transcending heterosubtypic immunity to influenza virus. In a murine model of influenza infection (IAV), we have found that sublethal thorax targeted radiation resulted in the rapid numerical decline of lung T RMwithout major alterations in circulating IAV-specific memory CD8+ T cells. The depletion of anti-IAV lung T RMwas long-lasting, and resulted in the loss of heterosubtypic immunity to IAV. Interestingly, any surviving T RMdisplay elevated granzyme B expression, indicating functional consequences for T RMfollowing radiation exposure, which could have implications for immune-mediated pathology. Designing effective vaccination strategies to reinvigorate this critical T cell subset will be an important step in combating the immunological effects of radiation exposure. 1F32AI174382-01

Further Characterization of Multi-Organ DEARE and Protection by 16,16 Dimethyl Prostaglandin E2 in a Mouse Model of the Hematopoietic Acute Radiation Syndrome.

Survivors of acute radiation exposure suffer from the delayed effects of acute radiation exposure (DEARE), a chronic condition affecting multiple organs, including lung, kidney, heart, gastrointestinal tract, eyes, and brain, and often causing cancer. While effective medical countermeasures (MCM) for the hematopoietic-acute radiation syndrome (H-ARS) have been identified and approved by the FDA, development of MCM for DEARE has not yet been successful. We previously documented residual bone marrow damage (RBMD) and progressive renal and cardiovascular DEARE in murine survivors of H-ARS, and significant survival efficacy of 16,16-dimethyl prostaglandin E2 (dmPGE2) given as a radioprotectant or radiomitigator for H-ARS. We now describe additional DEARE (physiological and neural function, progressive fur graying, ocular inflammation, and malignancy) developing after sub-threshold doses in our H-ARS model, and detailed analysis of the effects of dmPGE2 administered before (PGE-pre) or after (PGE-post) lethal total-body irradiation (TBI) on these DEARE. Administration of PGE-pre normalized the twofold reduction of white blood cells (WBC) and lymphocytes seen in vehicle-treated survivors (Veh), and increased the number of bone marrow (BM) cells, splenocytes, thymocytes, and phenotypically defined hematopoietic progenitor cells (HPC) and hematopoietic stem cells (HSC) to levels equivalent to those in non-irradiated age-matched controls. PGE-pre significantly protected HPC colony formation ex vivo by >twofold, long term-HSC in vivo engraftment potential up to ninefold, and significantly blunted TBI-induced myeloid skewing. Secondary transplantation documented continued production of LT-HSC with normal lineage differentiation. PGE-pre reduced development of DEARE cardiovascular pathologies and renal damage; prevented coronary artery rarefication, blunted progressive loss of coronary artery endothelia, reduced inflammation and coronary early senescence, and blunted radiation-induced increase in blood urea nitrogen (BUN). Ocular monocytes were significantly lower in PGE-pre mice, as was TBI-induced fur graying. Increased body weight and decreased frailty in male mice, and reduced incidence of thymic lymphoma were documented in PGE-pre mice. In assays measuring behavioral and cognitive functions, PGE-pre reduced anxiety in females, significantly blunted shock flinch response, and increased exploratory behavior in males. No effect of TBI was observed on memory in any group. PGE-post, despite significantly increasing 30-day survival in H-ARS and WBC and hematopoietic recovery, was not effective in reducing TBI-induced RBMD or any other DEARE. In summary, dmPGE2 administered as an H-ARS MCM before lethal TBI significantly increased 30-day survival and ameliorated RBMD and multi-organ and cognitive/behavioral DEARE to at least 12 months after TBI, whereas given after TBI, dmPGE2 enhances survival from H-ARS but has little impact on RBMD or other DEARE.