Gilbert W. Beebe Symposium on 30 Years after the Chernobyl Accident: Current and Future Studies on Radiation Health Effects

AZD 9668, a neutrophil elastase inhibitor, promotes wound healing in the irradiated skin by inhibiting NET-derived vascular dysfunction

Despite the increasing awareness of the health risks associated with radiation exposure such as radiotherapy and accidents, effective treatments remain limited except for bone marrow damage. Radiation-induced skin damage is a critical concern as it is often accompanied by severe inflammation and delayed wound healing. Endothelial cells have emerged as a promising therapeutic target for addressing such radiation-induced damage. Neutrophils, as key mediators of the early inflammatory response, play a pivotal role in this process. The formation of neutrophil extracellular trap (NET) is particularly noteworthy, as it may directly contribute to exacerbating vascular damage. However, studies specifically exploring the role of NETs in radiation-induced skin injury and their impact on endothelial barrier function are limited. Therefore, this study aimed to evaluate the use of AZD9668, an orally administered NE inhibitor, as a therapeutic agent to mitigate NET-induced endothelial and skin damage. Irradiated skin showed increased neutrophil infiltration, NET formation, and vascular permeability in the mouse model. Neutrophil elastase (NE) inhibitor, AZD9668, decreased NET formation and NET-derived NE activity. And AZD9668 treatment restored endothelial dysfunction and regulated antioxidative factors in NET-treated irradiated HUVECs. In mouse model of radiation-induced skin injury, oral administration of AZD9668 improved endothelial tight junction expression, vascular leakage, and inflammatory reaction. Therefore, skin wound healing accelerated in the AZD9668-treated group. This study highlights the critical role of NET in radiation-induced skin damage and endothelial barrier disruption, addressing a previously underexplored area. AZD9668 effectively mitigated radiation-induced damage by preventing NET formation, preserving tight junction integrity, and reducing inflammation. These findings underscore the therapeutic potential of NET and NET-derived NE in the management of radiation-induced vascular and skin injuries.

Sex differences in radiation research

PURPOSE

The Sex Differences in Radiation Research workshop addressed the role of sex as a confounder in radiation research and its implication in real-world radiological and nuclear applications.

METHODS

In April 2022, HHS-wide partners from the Radiation and Nuclear Countermeasures Program, the Office of Research on Women's Health National Institutes of Health Office of Women's Health, U.S. Food and Drug Administration, and the Radiological and Nuclear Countermeasures Branch at the Biomedical Advanced Research and Development Authority conducted a workshop to address the scientific implication and knowledge gaps in understanding sex in basic and translational research. The goals of this workshop were to examine sex differences in 1. Radiation animal models and understand how these may affect radiation medical countermeasure development; 2. Biodosimetry and/or biomarkers used to assess acute radiation syndrome, delayed effects of acute radiation exposure, and/or predict major organ morbidities; 3. medical research that lacks representation from both sexes. In addition, regulatory policies that influence inclusion of women in research, and the gaps that exist in drug development and device clearance were discussed. Finally, real-world sex differences in human health scenarios were also considered.

RESULTS

This report provides an overview of the two-day workshop, and open discussion among academic investigators, industry researchers, and U.S. government representatives.

CONCLUSIONS

This meeting highlighted that current study designs lack the power to determine statistical significance based on sex, and much is unknown about the underlying factors that contribute to these differences. Investigators should accommodate both sexes in all stages of research to ensure that the outcome is robust, reproducible, and accurate, and will benefit public health.

How the Science of Radiation Biology Can Help Reduce the Crippling Fear of Low-level Radiation

ABSTRACT

The fear of radiation has been present almost since the discovery of radiation, but has intensified since the "dawn of the atomic age" over 75 y ago. This fear has often served as an impediment to the safe and beneficial uses of radiation and radioactive material. The underlying causes of such fear are varied, can be complex, and are often not associated with any scientific knowledge or understanding. The authors believe that a clear understanding of the current scientific knowledge and understanding of the effects of radiation exposure may be useful in helping to allay some of the fear of radiation. This manuscript attempts to (1) address several scientific questions that we believe have contributed to the fear of radiation, (2) review the data derived from research that can be used to address these questions, and (3) summarize how the results of such scientific research can be used to help address the fear of low-dose and low-dose-rate radiation. Several examples of how fear of radiation has affected public perception of radiological events are discussed, as well as a brief history of the etiology of radiation fear. Actions needed to reduce the public fear of radiation and help fulfill the full societal benefits of radiation and radioactive materials are suggested.

Inadvertent Radiation Exposures in Combat Zones: Risk of Contamination and Radiobiologic Consequences

On February 24, 2022, Russia began a military invasion of Ukraine. Missile and air strikes were reported throughout the country, shortly followed by a large ground invasion from multiple directions. Four major theaters developed: the Kyiv offensive, the Northeastern Ukraine offensive, the Eastern Ukraine offensive, and the Southern Ukraine offensive, with continued missile and air strikes far into Western Ukraine. Advancing Russian military units launched an attack and captured the Chernobyl nuclear station. Russian troops dug trenches into the area commonly known as the "Red Forest," violating the established radiation safety measures and threatening security within the Chernobyl Exclusion Zone. The placement of military units in such close proximity to the station also sparked concerns of possible damage occurring to the containment vessel constructed around the station's wrecked fourth reactor. There are 15 operating nuclear reactors in Ukraine. Each is vulnerable to an attack or sabotage that could precipitate a malfunction and possible release of radioactive isotopes. In this short commentary, we will discuss radiobiologic data obtained after the analysis of historical nuclear power plant (NPP) accidents and emphasize new challenges for nuclear security when NPPs are found and are possible targets within a conflict zone.

Lung cancer mortality in Europe and the USA between 2000 and 2017: an observational analysis

BACKGROUND

The lung is the most common site for cancer and has the highest worldwide cancer-related mortality. Our study reports and compares trends in lung cancer mortality in the USA and 26 European countries.

STUDY DESIGN AND METHODS

Lung cancer mortality data were extracted for males and females for each of the years 2000-2017 from the World Health Organization (WHO) Mortality and the Centers for Disease Control and Prevention (CDC) WONDER databases. Lung cancer mortality trends were compared using Joinpoint regression analysis, and male-to-female mortality ratios were calculated.

RESULTS

Down-trending lung cancer mortality rates were observed in males in all countries except Cyprus and Portugal between 2000 and 2017. In females, increasing mortality rates were observed in 22 of the 27 countries analysed. Latvia had the highest estimated annual percentage change (EAPC) in male mortality (-9.6%) between 2013 and 2015. In the USA, EAPCs were -5.1% for males and -4.2% for females between 2014 and 2017. All countries had an overall decrease in the ratio of male-to-female lung cancer mortality. The most recent observation of median male-to-female mortality was 2.26 (IQR 1.92-4.05). The countries with the greatest current sex disparity in lung cancer mortality were Lithuania (5.51) and Latvia (5.00).

CONCLUSION

Between 2000 and 2017, lung cancer mortality rates were decreasing for males in Europe and the USA, whereas increasing lung cancer mortality rates were generally observed in females. There is a persistent but decreasing sex-mortality gap, with men having persistently greater lung cancer mortality but with rates decreasing faster than women.

Small-area methods for investigation of environment and health

Small-area studies offer a powerful epidemiological approach to study disease patterns at the population level and assess health risks posed by environmental pollutants. They involve a public health investigation on a geographical scale (e.g. neighbourhood) with overlay of health, environmental, demographic and potential confounder data. Recent methodological advances, including Bayesian approaches, combined with fast-growing computational capabilities, permit more informative analyses than previously possible, including the incorporation of data at different scales, from satellites to individual-level survey information. Better data availability has widened the scope and utility of small-area studies, but has also led to greater complexity, including choice of optimal study area size and extent, duration of study periods, range of covariates and confounders to be considered and dealing with uncertainty. The availability of data from large, well-phenotyped cohorts such as UK Biobank enables the use of mixed-level study designs and the triangulation of evidence on environmental risks from small-area and individual-level studies, therefore improving causal inference, including use of linked biomarker and -omics data. As a result, there are now improved opportunities to investigate the impacts of environmental risk factors on human health, particularly for the surveillance and prevention of non-communicable diseases.

Nrf2-modulation by seleno-hormetic agents and its potential for radiation protection

The trace element selenium (Se) is an essential component of selenoproteins and plays a critical role in redox signaling via regulating the activity of selenoenzymes such as thioredoxin reductase-1 and glutathione peroxidases. Se compounds and its metabolites possess a wide range of biological functions including anticancer and cytoprotection effects, modulation of hormetic genes and antioxidant enzyme activities. Radiation-induced injury of normal tissues is a significant side effect for cancer patients who receive radiotherapy in the clinic and the development of new and effective radioprotectors is an important goal of research. Others and we have shown that seleno-compounds have the potential to protect ionizing radiation-induced toxicities in various tissues and cells both in in vitro and in vivo studies. In this review, we discuss the potential utilization of Se compounds with redox-dependent hormetic activity as novel radio-protective agents to alleviate radiation toxicity. The cellular and molecular mechanisms underlying the radioprotection effects of these seleno-hormetic agents are also discussed. These include Nrf2 transcription factor modulation and the consequent upregulation of the adaptive stress response to IR in bone marrow stem cells and hematopoietic precursors.

Cancers after Chornobyl: From Epidemiology to Molecular Quantification

An overview and new data are presented from cancer studies of the most exposed groups of the population after the Chornobyl accident, performed at the National Research Center for Radiation Medicine (NRCRM). Incidence rates of solid cancers were analyzed for the 1990-2016 period in cleanup workers, evacuees, and the general population from the contaminated areas. In male cleanup workers, the significant increase in rates was demonstrated for cancers in total, leukemia, lymphoma, and thyroid cancer, as well as breast cancer rates were increased in females. Significantly elevated thyroid cancer incidence was identified in the male cleanup workers cohort (150,813) in 1986-2012 with an overall standardized incidence ratio (SIR) of 3.35 (95% CI: 2.91-3.80). A slight decrease in incidence rates was registered starting at 25 years after exposure. In total, 32 of 57 deaths in a group of cleanup workers with confirmed acute radiation syndrome (ARS) or not confirmed ARS (ARS NC) were due to blood malignancies or cancer. Molecular studies in cohort members included gene expression and polymorphism, FISH, relative telomere length, immunophenotype, micronuclei test, histone H2AX, and TORCH infections. Analysis of chronic lymphocytic leukemia (CLL) cases from the cohort showed more frequent mutations in telomere maintenance pathway genes as compared with unexposed CLL patients.

Radiation-induced papillary thyroid cancer: is it a distinct clinical entity?

PURPOSE OF REVIEW

To present the current status of knowledge regarding radiation-induced papillary thyroid cancer (RIPTC), defining its epidemiologic, pathologic, and clinical characteristics, with ensuing possible therapeutic and prognostic consequences.

RECENT FINDINGS

Cumulative evidence shows that RIPTC resembles sporadic papillary thyroid cancer (PTC) of comparable age, both in terms of clinical-pathological features and prognosis. Therefore, more aggressive treatment does not seem to be required when managing RIPTC as its prognosis is comparable to that of never-irradiated patients.

SUMMARY

Radiation exposure in childhood is a well-documented risk factor for development of PTC. Therefore, increased exposure to medical or environmental radiation may be in part responsible, along with increased screening, of the recent burgeoning incidence of PTC. A specific morphological and molecular portrait of RIPTC is unlikely to exist. The more aggressive histologic and clinical features initially reported in radiation-induced cases are consistent with the expectations in nonradiation-related PTC of a comparable age. Aggressive histology, nodal, and distant metastases correlate with early age at onset rather than with radiation exposure. Although relapses are frequent in children, long-term cancer-specific mortality is approximately 1%, lower than that observed for adults and comparable between irradiated and nonirradiated cohorts. RIPTC does not require more aggressive surgery or more adjuvant treatments, as prognosis is as good as that of sporadic PTC when matched for stage and treatment received.