Immune Dysfunction from Radiation Exposure

Radiation-Induced Tissue Regeneration: Pathways, Mechanisms, and Therapeutic Potential

This article explores the paradoxic nature of radiation as both a destructive and regenerative force. The article examines the interplay of signaling pathways, immune modulation, and stem cells in tissue regeneration post radiation, emphasizing the roles of key pathways like Wnt, Hedgehog, Notch, and p53. It highlights advancements in low-dose radiation therapy, extracellular vesicles, and stem cell-based interventions. Furthermore, the immune system's dual role in repair and damage is dissected, along with technologies such as artificial intelligence and bioengineered scaffolds that enhance therapeutic outcomes. The article offers a roadmap for integrating therapeutic innovation with regenerative medicine to improve patient outcomes.

Expected role of photodynamic therapy to relieve skin damage in nuclear or radiological emergency: Review

Nuclear and radiological accidents can occur due to poor management, in transportation, radiation therapy and nuclear wards in hospitals, leading to extreme radiation exposure and serious consequences for human health. Additionally, in many of previous radiological accidents, skin damage was observed in patients and survivors due to the high radiation exposure. However, as part of a medical countermeasures in a nuclear/radiological emergency, it is critical to plan for the treatment of radiation-induced skin damage. Hence, the new, non-invasive technology of photodynamic therapy (PDT) is projected to be more effectively used for treating skin damage caused by high-dose radiation. PDT plays an important role in treating, repairing skin damage and promoting wound healing as evidenced by research. This review, highlighted and recommended potential impacts of PDT to repair and decrease radiation-induced skin tissue damage. Moreover, we have suggested some photosensitizer (PS) agent as radio-mitigator drugs to decrease radiobiological effects.

T lymphocyte and neutrophil/lymphocyte ratio in patients with radiation-induced oral mucositis after intensity-modulated radiation therapy for head and neck cancer: A retrospective single-center study

To investigate T lymphocyte, neutrophil/lymphocyte ratio (NLR) and their impact on patients with radiation-induced oral mucositis (RIOM) after intensity-modulated radiotherapy for head and neck cancer. The clinical data of 148 patients diagnosed with head and neck cancer from January 2016 to January 2019 were retrospectively analyzed. Patients were divided into RIOM group (n = 42 cases) and non-RIOM group (n = 106 cases), based on whether they developed RIOM after intensity-modulated radiation therapy. The T lymphocyte and NLR of the 2 groups were analyzed before and after treatment; The correlation between T lymphocyte and NLR in RIOM group was analyzed. We used RTOG grading system to evaluate and scale the RIOM. The relationship between the grade of RIOM, T lymphocyte and NLR in RIOM group was analyzed. After treatment, the proportion of CD3 +, CD4 +, and CD8 + T lymphocytes in the 2 groups after treatment were decreased, and the RIOM group was significantly lower than non-RIOM group, P < .05. NLR in RIOM group was significantly higher than that in non-RIOM group, P < .05. The data of overall survival showed no significant differences between 2 groups (HR = 0.82, 95% CI: 0.43-1.59). Compared with RIOM group, patients in non-RIOM group showed a longer progress-free survival (HR = 0.57, 95% CI: 0.33-0.99). In RIOM group, NLR was negatively correlated with CD3 + (r = -0.433, P = .004), CD4 + (r = -0.644, P < .001) and CD8 + T cells (r = -0.665, P < .001). RIOM was positively correlated with NLR (R = 0.621, P < .001), negatively correlated with CD4 + T cell ratio (r = -0.449, P = .003) and CD8 + T cell ratio (r = -0.307, P = .048), but RIOM did not correlate with CD3 + T cell ratio (r = -0.225, P = .152). For patients with RIOM after intensity-modulated radiotherapy for head and neck cancer, T lymphocyte showed a downward trend, and NLR showed an upward trend. In addition, T lymphocyte and NLR are closely related to the RIOM, indicating that clinicians should be aware of the importance of T lymphocyte and NLR on patients received radiotherapy.

Transplantation of Donor-Recipient Chimeric Cells Restores Peripheral Blood Cell Populations and Increases Survival after Total Body Irradiation-Induced Injury in a Rat Experimental Model

Current therapies for acute radiation syndrome (ARS) involve bone marrow transplantation (BMT), leading to graft-versus-host disease (GvHD). To address this challenge, we have developed a novel donor-recipient chimeric cell (DRCC) therapy to increase survival and prevent GvHD following total body irradiation (TBI)-induced hematopoietic injury without the need for immunosuppression. In this study, 20 Lewis rats were exposed to 7 Gy TBI to induce ARS, and we assessed the efficacy of various cellular therapies following systemic intraosseous administration. Twenty Lewis rats were randomly divided into four experimental groups (n = 5/group): saline control, allogeneic bone marrow transplantation (alloBMT), DRCC, and alloBMT + DRCC. DRCC were created by polyethylene glycol-mediated fusion of bone marrow cells from 24 ACI (RT1a) and 24 Lewis (RT11) rat donors. Fusion feasibility was confirmed by flow cytometry and confocal microscopy. The impact of different therapies on post-irradiation peripheral blood cell recovery was evaluated through complete blood count, while GvHD signs were monitored clinically and histopathologically. The chimeric state of DRCC was confirmed. Post-alloBMT mortality was 60%, whereas DRCC and alloBMT + DRCC therapies achieved 100% survival. DRCC therapy also led to the highest white blood cell counts and minimal GvHD changes in kidney and skin samples, in contrast to alloBMT treatment. In this study, transplantation of DRCC promoted the recovery of peripheral blood cell populations after TBI without the development of GVHD. This study introduces a novel and promising DRCC-based bridging therapy for treating ARS and extending survival without GvHD.

Immune Dysfunction from Radiation Exposure

Exposure to ionizing radiation causes acute damage and loss of bone marrow and peripheral immune cells that can result in high mortality due to reduced resistance to infections and hemorrhage. Besides these acute effects, tissue damage from radiation can trigger inflammatory responses, leading to progressive and chronic tissue damage by radiation-induced loss of immune cell types that are required for resolving tissue injuries. Understanding the mechanisms involved in radiation-induced immune system injury and repair will provide new insights for developing medical countermeasures that help restore immune homeostasis. For these reasons, The Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID) convened a two-day workshop, along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN). This workshop, titled "Immune Dysfunction from Radiation Exposure," was held virtually on September 9-10, 2020; this Commentary provides a high-level overview of what was discussed at the meeting.