Single-Cell Transcriptomics Reveals Early Effects of Ionizing Radiation on Bone Marrow Mononuclear Cells in Mice.

Ionizing radiation exposure can cause damage to diverse tissues and organs, with the hematopoietic system being the most sensitive. However, limited information is available regarding the radiosensitivity of various hematopoietic cell populations in the bone marrow due to the high heterogeneity of the hematopoietic system. In this study, we observed that granulocyte-macrophage progenitors, hematopoietic stem/progenitor cells, and B cells within the bone marrow showed the highest sensitivity, exhibiting a rapid decrease in cell numbers following irradiation. Nonetheless, neutrophils, natural killer (NK) cells, T cells, and dendritic cells demonstrated a certain degree of radioresistance, with neutrophils exhibiting the most pronounced resistance. By employing single-cell transcriptome sequencing, we investigated the early responsive genes in various cell types following irradiation, revealing that distinct gene expression profiles emerged between radiosensitive and radioresistant cells. In B cells, radiation exposure led to a specific upregulation of genes associated with mitochondrial respiratory chain complexes, suggesting a connection between these complexes and cell radiosensitivity. In neutrophils, radiation exposure resulted in fewer gene alterations, indicating their potential for distinct mechanisms in radiation resistance. Collectively, this study provides insights into the molecular mechanism for the heterogeneity of radiosensitivity among the various bone marrow hematopoietic cell populations.

Sequential radiation exposure: uncovering the potential of low dose ionizing radiation in mitigating high dose effects on immune cells.

PURPOSE: The radioadaptive response refers to a phenomenon wherein exposure to a low dose of ionizing radiation (LDIR) can induce a protective response in cells or organisms, reducing the adverse effects of a subsequent higher dose of ionizing radiation (HDIR). However, it is possible to administer the low dose after the challenge dose. This study was conducted to determine the potential mitigating effect of LDIR administered after HDIR on mice immune cells. MATERIALS AND METHODS: Alongside the conventional adaptive response setting, one group of mice was initially exposed to HDIR and subsequently treated with LDIR. Neutrophil activation was done using DHR-reducing assay and cell proliferation was evaluated through CFSE-dilution assay in helper (CD4+) and cytotoxic (CD8+) T cells. Cytokine production by these T cell subsets was also assessed by intracellular staining using flow cytometry. RESULTS: The results of this study revealed no change in neutrophil function between any of the mice groups compared to the untreated control group. Although significant changes were not detected in the proliferation of CD4+ T cells, decreased proliferation was observed in stimulated CD8+ T cells in the HDIR group. In contrast to IFN-É£, which showed no evident change in either of the T cell subsets after stimulation, IL-4 was rigorously dropped in stimulated CD4+ T cells in the HDIR group. CONCLUSIONS: In summary, the results of this study indicated that the administration of LDIR to mice before HDIR was not able to reduce the detrimental effects of HDIR in our experimental setting. Instead, we observed a mitigating effect of LDIR when administered after the challenge dose. This suggests that not only the dose and duration but also the order of LDIR relative to HDIR affects its efficacy.

Low-Dose Ionizing γ-Radiation Elicits the Extrusion of Neutrophil Extracellular Traps.

PURPOSE: Patients with cancer frequently undergo radiotherapy in their clinical management with unintended irradiation of blood vessels and copiously irrigated organs in which polymorphonuclear leukocytes circulate. Following the observation that such low doses of ionizing radiation are able to induce neutrophils to extrude neutrophil extracellular traps (NET), we have investigated the mechanisms, consequences, and occurrence of such phenomena in patients undergoing radiotherapy. EXPERIMENTAL DESIGN: NETosis was analyzed in cultures of neutrophils isolated from healthy donors, patients with cancer, and cancer-bearing mice under confocal microscopy. Cocultures of radiation-induced NETs, immune effector lymphocytes, and tumor cells were used to study the effects of irradiation-induced NETs on immune cytotoxicity. Radiation-induced NETs were intravenously injected to mice for assessing their effects on metastasis. Circulating NETs in irradiated patients with cancer were measured using ELISA methods for detecting MPO-DNA complexes and citrullinated histone 3. RESULTS: Irradiation of neutrophils with very low γ-radiation doses (0.5-1 Gy) elicits NET formation in a manner dependent on oxidative stress, NADPH oxidase activity, and autocrine IL8. Radiation-induced NETs interfere with NK cell and T-cell cytotoxicity. As a consequence, preinjection of irradiation-induced NETs increases the number of successful metastases in mouse tumor models. Increases in circulating NETs were readily detected in two prospective series of patients following the first fraction of their radiotherapy courses. CONCLUSIONS: NETosis is induced by low-dose ionizing irradiation in a neutrophil-intrinsic fashion, and radiation-induced NETs are able to interfere with immune-mediated cytotoxicity. Radiation-induced NETs foster metastasis in mouse models and can be detected in the circulation of patients undergoing conventional radiotherapy treatments. See related commentary by Mowery and Luke, p. 3965.

Engineered nanoceria modulate neutrophil oxidative response to low doses of UV-B radiation through the inhibition of reactive oxygen species production.

To avoid aging and ultraviolet mediated skin disease the cell repair machinery must work properly. Neutrophils, also known as polymorphonuclear leukocytes, are the first and most abundant cell types which infiltrate sites of irradiation and play an important role in restoring the microenvironment homeostasis. However, the infiltration of neutrophils in ultraviolet-B (UV-B) irradiated skin might also contribute to the pathophysiology of skin disease. The polymorphonuclear leukocytes activation induced by UV-B exposure may lead to prolonged, sustained NADPH oxidase activation followed by an increase in reactive oxygen species (ROS) production. Our previous work showed that cerium oxide nanoparticles can protect L929 fibroblasts from ultraviolet-B induced damage. Herein, we further our investigation of engineered cerium oxide nanoparticles (CNP) in conferring radiation protection specifically in modulation of neutrophils' oxidative response under low dose of UV-B radiation. Our data showed that even low doses of UV-B radiation activate neutrophils' oxidative response and that the antioxidant, ROS-sensitive redox activities of engineered CNPs are able to inhibit the effects of NADPH oxidase activation while conferring catalase and superoxide dismutase mimetic activity. Further, our investigations revealed similar levels of total ROS scavenging for both CNP formulations, despite substantial differences in cerium redox states and specific enzyme-mimetic reaction activity. We therefore determine that CNP activity in mitigating the effects of neutrophils' oxidative response, through the decrease of ROS and of cell damage such as chromatin condensation, suggests potential utility as a radio-protectant/therapeutic against UV-B damage.

Acute skin exposure to ultraviolet light triggers neutrophil-mediated kidney inflammation.

Photosensitivity to ultraviolet (UV) light affects up to ∼80% of lupus patients. Sunlight exposure can exacerbate local as well as systemic manifestations of lupus, including nephritis, by mechanisms that are poorly understood. Here, we report that acute skin exposure to UV light triggers a neutrophil-dependent injury response in the kidney characterized by upregulated expression of endothelial adhesion molecules as well as inflammatory and injury markers associated with transient proteinuria. We showed that UV light stimulates neutrophil migration not only to the skin but also to the kidney in an IL-17A-dependent manner. Using a photoactivatable lineage tracing approach, we observed that a subset of neutrophils found in the kidney had transited through UV light-exposed skin, suggesting reverse transmigration. Besides being required for the renal induction of genes encoding mediators of inflammation (vcam-1, s100A9, and Il-1b) and injury (lipocalin-2 and kim-1), neutrophils significantly contributed to the kidney type I interferon signature triggered by UV light. Together, these findings demonstrate that neutrophils mediate subclinical renal inflammation and injury following skin exposure to UV light. Of interest, patients with lupus have subpopulations of blood neutrophils and low-density granulocytes with similar phenotypes to reverse transmigrating neutrophils observed in the mice post-UV exposure, suggesting that these cells could have transmigrated from inflamed tissue, such as the skin.

Pretreatment Neutrophil-to-Lymphocyte Ratio Predicts Survival and Liver Toxicity in Patients With Hepatocellular Carcinoma Treated With Stereotactic Ablative Radiation Therapy.

PURPOSE: The objective of this study was to determine whether pretreatment neutrophil-to-lymphocyte ratio (NLR) could predict survival outcomes and liver toxicity in hepatocellular carcinoma (HCC) patients treated with stereotactic ablative radiation therapy (SABR). METHODS AND MATERIALS: In this retrospective study we collected pretreatment NLR of HCC patients treated with SABR between December 2007 and August 2018 and determined its association with overall survival (OS), progression-free survival, and radiation-related liver toxicity defined as an increase in the Child-Turcotte-Pugh score by ≥2 within 3 months after SABR in the absence of disease progression. RESULTS: A total of 153 patients with a median follow-up of 13.3 months were included. Receiver operating characteristic curve analysis found that an NLR ≥2.4 was optimum (area under the curve, 0.762; 95% confidence interval [CI], 0.682-0.841, P < .001) for predicting poor 1-year OS (38.2% vs 83.6%, P < .001). Multivariable analysis demonstrated that NLR was significantly associated with OS, both as a continuous (P = .006) and a binary variable (NLR set at 2.4; P = .003). Multiple tumors (P = .003), macrovascular invasion (P = .024), extrahepatic spread (P = .002), and albumin-bilirubin score (P = .020) were also significant predictors of OS. Elevated NLR independently prognosticated poor progression-free survival (P = .016). Liver toxicity was seen in 22 evaluable patients (15.4%). Receiver operating characteristic curve analysis found NLR ≥4.0 was optimum at predicting liver toxicity (31.4% vs 10.2%, P = .005). A higher NLR (P = .049) and albumin-bilirubin score (P = .002) were independent risk factors for liver toxicity. CONCLUSIONS: NLR is an objective and ubiquitous inflammatory marker that can predict OS and liver toxicity in HCC patients undergoing SABR. NLR could be a useful biomarker for patient risk stratification and therapeutic decision-making.

Pretreatment peripheral neutrophils, lymphocytes and monocytes predict long-term survival in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is an inflammation-related cancer, where nonresolving inflammation contributes to its development and progression. Peripheral inflammatory cells have been shown to be associated with the prognosis of various types of cancer. The present study investigated the utility of pretreatment peripheral inflammatory cells in the prognosis of patients with HCC. METHODS: We retrospectively analyzed data regarding peripheral inflammatory cell, and patient and tumor characteristics from patients with HCC who were diagnosed between November 2008 and March 2018. Baseline data, including peripheral inflammatory cell counts, were recorded before treatment. The relationships between overall survival (OS) and study variables were assessed. RESULTS: A total of 1681 patients who were diagnosed with HCC were included. In univariate and multivariate analyses, individual neutrophil, lymphocyte and monocyte cell counts were found as independent indicators of poor OS. High neutrophil (≥3100 × 106/L) and, monocyte (≥470 × 106/L) counts and low lymphocyte counts (< 1640 × 106/L) significantly associated with reduced OS (p < 0.05). Neutrophil and, monocyte cell counts rose and lymphocyte counts decreased in association with advancing the Barcelona Clinic Liver Cancer stage (P < 0.001). CONCLUSIONS: Pretreatment peripheral neutrophils, lymphocytes, and monocytes are independently associated with outcomes of patients with HCC. These cells provides a noninvasive, low-cost, easy, and reproducible biomarker that can be used in routine clinical practice to predict the prognosis of patients with HCC.

The post-treatment neutrophil-to-lymphocyte ratio and changes in this ratio predict survival after treatment of stage III non-small-cell lung cancer with conventionally fractionated radiotherapy.

Aim: To investigate the predictive potential of post-treatment neutrophil-to-lymphocyte ratio (NLR) and changes in this ratio (ΔNLR) for stage III non-small-cell lung cancer (NSCLC) patients who received conventionally fractionated radiotherapy (CFRT). Patients & methods: The data of 168 NSCLC patients treated at the Shandong Cancer Hospital were analyzed retrospectively. The relationship between progression-free survival (PFS), overall survival (OS) and post-treatment NLR and ΔNLR were analyzed using both Kaplan-Meier and Cox regression methods. Results: Kaplan-Meier survival analyses showed that post-treatment NLR and ΔNLR were associated with PFS (p < 0.001) and OS (p < 0.001) after CFRT. Multivariate analyses revealed that ΔNLR was an independent predictor of PFS (p = 0.001) and OS (p = 0.018). Post-treatment NLR can only be used as an independent predictor of PFS (p = 0.040). Conclusion: Our results demonstrated the prognostic value of the ΔNLR in predicting PFS and OS in stage III NSCLC patients undergoing CFRT. However, post-treatment NLR has predictive value only for PFS.

The prognostic value of the ratio of neutrophils to lymphocytes before and after intensity modulated radiotherapy for patients with nasopharyngeal carcinoma.

This study aimed to determine the impact of the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) on the prognosis of nasopharyngeal carcinoma (NPC) before and after intensity modulated radiotherapy (IMRT).Pre/post-treatment and changes in inflammatory biomarker levels of 207 patients who were diagnosed with NPC and received IMRT between January 2012 and December 2014 were analyzed, and the cellular biomarker analyses were from patient blood. ROC (receiver operating characteristic) analysis was used to decide the optimal cutoff values of NLR and changes in NLR (ΔNLR) and PLR (ΔPLR). The Kaplan-Meier and logarithmic rank methods were used to compare overall survival times between groups. Univariate analysis was used to investigate the effects of age, gender, histology, Karnofsky performance score (KPS), TNM stage, clinical stage, course of disease and lymphocyte, neutrophil and platelet counts as well as alkaline phosphatase (ALP) levels on the prognosis of NPC. The independent predictors of OS were determined by Cox multivariate regression analysis.The optimal cut-off values of NLR, PLR, ΔNLR and ΔPLR were 2.49, 155.82, 1.80, and 100.00, respectively. These were used to classify patients into high (NLR > 2.49) and low NLR groups (NLR < 2.49); high (PLR>155.82) and low (PLR < 155.82) PLR groups; high (ΔNLR>1.80) and low ΔNLR groups (ΔNLR < 1.80); high (ΔPLR > 100.00) and low ΔPLR groups (ΔPLR < 100.00). TNM stage, clinical stage and ALP levels were highly correlated with high NLR and PLR. Cox multivariate regression analysis suggested that the ΔNLR (HR = 2.89, 95% CI: 1.33∼2.78) was independent of the characteristics for NPC.As a novel inflammatory index, ΔNLR appears to have some predictive power for the prognosis of patients with NPC.

Effect of hyperthermia on improving neutrophil restoration after intraperitoneal chemotherapy.

Purpose: Intraperitoneal (IP) chemotherapy has several benefits but also can have severe hematologic side effects. We compared the effects of hyperthermic intraperitoneal chemotherapy (HIPEC) and conventional IP chemotherapy on bone marrow suppression and evaluated whether HIPEC increased neutrophil recovery.Methods: HIPEC or IP chemotherapy was administered to ovarian cancer-bearing mice. Bone marrow progenitor cell colony-forming unit (CFU) count, serum cytokine levels, and peripheral leukocyte count after HIPEC and IP chemotherapy were compared.Results: Peripheral neutrophil count, cytokine (G-CSF and CXCL1/KC) levels, and bone marrow progenitor cell CFU count were significantly higher after HIPEC than after IP chemotherapy.Conclusions: Hyperthermia increased the serum neutrophil-recruiting cytokine levels and reduced the magnitude of chemotherapy-induced neutropenia. Thus, HIPEC improved neutrophil and bone marrow recovery compared with conventional IP chemotherapy.

TISSUE IMMUNE CELLS AND THEIR ROLE IN THE HEALING PROCESS OF INFECTED RADIATION ULCERS UNDER THE IMPACT OF PHOTODYNAMIC THERAPY (EXPERIMENTAL STUDY). / TKANYNNI IMUNNI KLITYNY TA ÏKh ROL' U PROTsESAKh ZAGOIeNNIa INFIKOVANYKh PROMENEVYKh VYRAZOK PRY VPLYVI FOTODYNAMIChNOÏ TERAPIÏ (EKSPERYMENTAL'NE DOSLIDZhENNIa).

OBJECTIVE: to study the effect of antibacterial photodynamic therapy (PDT) on the dynamics of tissue neutrophilic leukocytes CD18 and tissue macrophages ED1 in the tissues of infected radiation ulcer during the stages of sponta- neous healing and in the treatment of PDTMaterials and methods. Infected radiation ulcer was modeled by local X-ray irradiation of the rat thigh skin at a dose of 85.0 Gy, followed by applying to the surface of the ulcer bacterial suspension of S. аureus. PDT was performed using a «Barva-LED/630¼ photonic apparatus and a methylene blue photosensitizer. The effect of PDT on the state of cellular immunity was determined using an immunohistochemical method based on the quantitative indices of neutrophilic leukocytes CD18 and ED1 macrophages during the stages of healing of an infected radiation ulcer. RESULTS: In the course of spontaneous healing of the ulcer (control I), the dynamics of changes in the relative vo- lume of tissue neutrophil leukocytes CD18 and ED1 macrophages in the lesion zone, a decrease in the CD18 / ED1 index more than 2 times indicated that switching of the neutrophil response to macrophage occurred before 52nd days of observations. When infected with S. аureus X-ray (control II), the switching of the neutrophil response to the macrophage did not occur during the entire observation period. When using PDT in the case of S. аureus infected ulcer (experimental group), the decrease in the CD18 / ED1 index was determined from the 21st day of observation. CONCLUSIONS: The positive effect of the antibacterial PDT method of infected S. аureus radiation ulcers was manifes- ted by complete microbial decontamination of the wound, reduction of phases of the wound process, complete hea- ling of radiation ulcers.The use of PDT has led to the death of bacteria, a decrease in the number of neutrophilic leukocytes and an increase in macrophages in the lesion area, the switching of the neutrophilic response to the reaction of monocyte-macrophage cells in the early stages of healing.

Blue and Long-Wave Ultraviolet Light Induce in vitro Neutrophil Extracellular Trap (NET) Formation.

Neutrophil Extracellular Traps (NETs) are produced by neutrophilic granulocytes and consist of decondensed chromatin decorated with antimicrobial peptides. They defend the organism against intruders and are released upon various stimuli including pathogens, mediators of inflammation, or chemical triggers. NET formation is also involved in inflammatory, cardiovascular, malignant diseases, and autoimmune disorders like rheumatoid arthritis, psoriasis, or systemic lupus erythematosus (SLE). In many autoimmune diseases like SLE or dermatomyositis, light of the ultraviolet-visible (UV-VIS) spectrum is well-known to trigger and aggravate disease severity. However, the underlying connection between NET formation, light exposure, and disease exacerbation remains elusive. We studied the effect of UVA (375 nm), blue (470 nm) and green (565 nm) light on NETosis in human neutrophils ex vivo. Our results show a dose- and wavelength-dependent induction of NETosis. Light-induced NETosis depended on the generation of extracellular reactive oxygen species (ROS) induced by riboflavin excitation and its subsequent reaction with tryptophan. The light-induced NETosis required both neutrophil elastase (NE) as well as myeloperoxidase (MPO) activation and induced histone citrullination. These findings suggest that NET formation as a response to light could be the hitherto missing link between elevated susceptibility to NET formation in autoimmune patients and photosensitivity for example in SLE and dermatomyositis patients. This novel connection could provide a clue for a deeper understanding of light-sensitive diseases in general and for the development of new pharmacological strategies to avoid disease exacerbation upon light exposure.

Mitigating Effects of 1-Palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) on Hematopoietic Acute Radiation Syndrome after Total-Body Ionizing Irradiation in Mice.

Acute radiation syndrome (ARS) occurs as a result of partial- or whole-body, high-dose exposure to radiation in a very short period of time. Survival is dependent on the severity of the hematopoietic sub-syndrome of ARS. In this study, we investigated the mitigating effects of a lipid molecule, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG), on the kinetics of hematopoietic cells, including absolute neutrophil count (ANC), red blood cells (RBCs) and platelet counts, in mice after gamma-ray total-body irradiation (TBI). Male and female BALB/c mice (11 weeks old) received a LD70/30 dose of TBI. PLAG significantly and dose-dependently attenuated radiation-induced mortality (P = 0.0041 for PLAG 50 mg/kg; P < 0.0001 for PLAG 250 mg/kg) and body weight loss (P < 0.0001 for PLAG 50 and 250 mg/kg) in mice. Single-fraction TBI sharply reduced ANC within 3 days postirradiation and maintained the neutropenic state (ANC < 500 cells/µl) by approximately 26.8 ± 0.8 days. However, administration of PLAG attenuated radiation-induced severe neutropenia (ANC < 100 cells/µl) by effectively delaying the mean day of its onset and decreasing its duration. PLAG also significantly mitigated radiation-induced thrombocytopenia (P < 0.0001 for PLAG 250 mg/kg) and anemia (P = 0.0023 for PLAG 250 mg/kg) by increasing mean platelet and RBC counts, as well as hemoglobin levels, in peripheral blood. Moreover, delayed administration of PLAG, even at 48 and 72 h after gamma-ray irradiation, significantly attenuated radiation-induced mortality in a time-dependent manner. When compared to olive oil and palmitic linoleic hydroxyl (PLH), only PLAG effectively attenuated radiation-induced mortality, indicating that it has a distinctive mechanism of action. Based on these preclinical observations, we concluded that PLAG has high potential as a radiation countermeasure for the improvement of survivability and the treatment of hematopoietic injury in gamma-ray-induced ARS.

Oral administration of 3,3'-diselenodipropionic acid prevents thoracic radiation induced pneumonitis in mice by suppressing NF-kB/IL-17/G-CSF/neutrophil axis.

The incidence of symptomatic radiation induced lung pneumonitis (RILP), a major dose limiting side effect of thoracic radiotherapy, is in the range of 15-40%. Therapeutic options for the prevention and treatment of RILP are limited. Hence there is a need for developing novel radioprotectors to prevent RILP which can be patient compliant. This study sought to evaluate the efficacy of oral 3,3'-diselenodipropionic acid (DSePA), a novel selenocystine derivative to prevent RILP. C3H/HeJ (pneumonitis responding) mice received a single dose of 18 Gy, whole thorax irradiation and a subset were treated with DSePA orally (2.5 mg/kg), three times per week beginning 2 h post irradiation and continued till 6 months. DSePA delayed onset of grade ≥ 2 RILP by 45 days compared to radiation control (~105 versus ~60 days). It also reversed the severity of pneumonitis in 3/10 radiation treated mice leading to significant improvement in asymptomatic survival compared to radiation control (~180 versus ~102 days). DSePA significantly (p < 0.05) reduced the radiation-mediated infiltration of polymorphonuclear neutrophils (PMN) and elevation in levels of cytokines such as IL1-ß, ICAM-1, E-selectin, IL-17 and TGF-ß in the bronchoalveolar lavage fluid. Moreover DSePA lowered PMN-induced oxidants, maintained glutathione peroxidase activity and suppressed NF-kB/IL-17/G-CSF/neutrophil axis in the lung of irradiated mice. Additionally, this compound did not protect A549 (lung cancer) derived xenograft tumor from radiation exposure in SCID mice. DSePA offers protection to normal lung against RILP without affecting radiation sensitivity of tumors. It has the potential to be developed as an oral agent for preventing RILP.

Impact of Radiation Dose to the Host Immune System on Tumor Control and Survival for Stage III Non-Small Cell Lung Cancer Treated with Definitive Radiation Therapy.

PURPOSE: The significance of radiation dose to the host immune system during the treatment of stage III non-small cell lung cancer (NSCLC) is unknown, but higher doses were associated with worse tumor control and overall survival (OS) in a secondary analysis of RTOG 0617. In this study, we sought to assess the impact of the estimated dose of radiation to immune cells (EDRIC) on cancer-specific outcomes in an independent cohort of patients treated at our institution. METHODS AND MATERIALS: We retrospectively identified 117 patients with stage III NSCLC treated with definitive fractionated radiation from 2004 to 2017 at a single academic center (median dose of 60 Gy; 60% underwent intensity modulated radiation therapy and 92% received concurrent platinum-based chemotherapy). EDRIC was calculated as a function of the number of radiation fractions and mean doses to the lung, heart, and remaining body based on a model developed by Jin et al. RESULTS: Median follow-up was 16 months with 77% of patients followed until death. In the entire population, 5-year OS was 11.2% with a median survival of 17.3 months. Median EDRIC for the entire cohort was 6.1 Gy (range, 2.5-10.0 Gy). A higher EDRIC was correlated with greater risk of grade ≥3 lymphopenia (P = .004). On multivariate analysis including total prescription radiation dose, planning target volume, and chemotherapy utilization, EDRIC was independently associated with OS (hazard ratio [HR] 1.17, P = .03), local progression-free survival (HR 1.17, P = .02), and disease-free survival (HR 1.15, P = .04). The median OS for patients with an EDRIC above 7.3 Gy (fourth quartile) and below 5.1 Gy (first quartile) was 14.3 and 28.2 months, respectively. CONCLUSIONS: Higher doses of radiation to the immune system were associated with tumor progression and death after the definitive treatment of stage III NSCLC. Tailoring radiation therapy to spare the immune system may be an important future direction to improve outcomes in this population.

Nanosecond pulsed electric fields induce extracellular release of chromosomal DNA and histone citrullination in neutrophil-differentiated HL-60 cells.

Nanosecond pulsed electric fields (nsPEFs) have gained attention as a novel physical stimulus for life sciences. Although cancer therapy is currently their promising application, nsPEFs have further potential owing to their ability to elicit various cellular responses. This study aimed to explore stimulatory actions of nsPEFs, and we used HL-60 cells that were differentiated into neutrophils under cultured conditions. Exposure of neutrophil-differentiated HL-60 cells to nsPEFs led to the extracellular release of chromosomal DNA, which appears to be equivalent to neutrophil extracellular traps (NETs) that serve as a host defense mechanism against pathogens. Fluorometric measurement of extracellular DNA showed that DNA extrusion was rapidly induced after nsPEF exposure and increased over time. Western blot analysis demonstrated that nsPEFs induced histone citrullination that is the hydrolytic conversion of arginine to citrulline on histones and facilitates chromatin decondensation. DNA extrusion and histone citrullination by nsPEFs were cell type-specific and Ca2+-dependent events. Taken together, these observations suggest that nsPEFs drive the mechanism for neutrophil-specific immune response without infection, highlighting a novel aspect of nsPEFs as a physical stimulus.

UVA and UVB radiation induce the formation of neutrophil extracellular traps by human polymorphonuclear cells.

Prolonged exposure of the skin to ultraviolet radiation (UV) leads to its damage and loss of protective properties. This condition called photoaging of the skin is caused by a number of destructive factors, such as reactive oxygen species (ROS) and proteolytic enzymes that cause damage to the extracellular matrix, e.g. collagen fibers. Many cells of the immune system, including neutrophils, are involved in the photoaging process. The presence of neutrophils in the skin exposed to UV irradiation is known; however, the mechanism of neutrophil activity at these conditions remains unclear. In our study, we focused on the ability of neutrophils to release neutrophil extracellular traps (NETs) and the role of these structures in the photoaging process. NET release occurs in response to various stimuli; however, we hereby showed that the UVA and UVB radiation that reaches the Earth's surface could activate the mechanism of netosis. UV-induced netosis was much faster than that activated by chemical or biological factors; however, it also occurred due to the production of ROS, known signal mediators in netosis. In this work, we also identified the probable netosis signaling pathway involved in the neutrophil response to UV. The participation of NET components may explain the ongoing process of skin photoaging, but it is also important to indicate netosis as a potential target for skin protection therapy. Antioxidants tested in this work, such as N-acetylcysteine, ethamsylate, as well as vitamin B1 (thiamine), can successfully inhibit UV-induced netosis, and thus be used as protective components against the negative effects of solar radiation.

Immune regeneration in irradiated mice is not impaired by the absence of DPP9 enzymatic activity.

The ubiquitous intracellular protease dipeptidyl peptidase 9 (DPP9) has roles in antigen presentation and B cell signaling. To investigate the importance of DPP9 in immune regeneration, primary and secondary chimeric mice were created in irradiated recipients using fetal liver cells and adult bone marrow cells, respectively, using wild-type (WT) and DPP9 gene-knockin (DPP9S729A) enzyme-inactive mice. Immune cell reconstitution was assessed at 6 and 16 weeks post-transplant. Primary chimeric mice successfully regenerated neutrophils, natural killer, T and B cells, irrespective of donor cell genotype. There were no significant differences in total myeloid cell or neutrophil numbers between DPP9-WT and DPP9S729A-reconstituted mice. In secondary chimeric mice, cells of DPP9S729A-origin cells displayed enhanced engraftment compared to WT. However, we observed no differences in myeloid or lymphoid lineage reconstitution between WT and DPP9S729A donors, indicating that hematopoietic stem cell (HSC) engraftment and self-renewal is not diminished by the absence of DPP9 enzymatic activity. This is the first report on transplantation of bone marrow cells that lack DPP9 enzymatic activity.

Chemoirradiated neutrophils and T cells differentially affect immune functions of APCs.

Extracorporeal photopheresis (ECP) is known as an immunomodulatory therapy with few side effects, which is mainly used in the treatment of cutaneous T cell lymphoma, graft-versus-host disease, and allograft rejection. During ECP, leukocytes are separated from whole blood by leukapheresis, subsequently chemoirradiated with 8-methoxypsoralen and UVA light, and re-infused into the patient. Although clinically effective, its mode of action has not been fully elucidated. In the present study, we analyzed the interaction of chemoirradiated neutrophils and CD3+ lymphocytes with APC in an in vitro model. We report that chemoirradiated CD3+ T cells induced increased expression of activation markers on dendritic cells (DC), macrophages, and monocytes. Coculture of chemoirradiated CD3+ T cells with these APC also led to significantly increased secretion of TNF-α. Although less pronounced, additional activation of APC took place when APC were stimulated with LPS or IFN-γ. In contrast, chemoirradiated neutrophils did not show activating effects on APC. The presence of chemoirradiated neutrophils during LPS and IFN-γ stimulation of DC rather diminished DC and macrophage activation. In line with these findings DC cocultured with chemoirradiated CD3+ T cells, but not neutrophils, showed significantly increased activation of CD3+ responder lymphocytes in a mixed lymphocyte reaction. With this study, we demonstrate that chemoirradiated leukocytes have differential indirect immunomodulatory effects. Whereas chemoirradiated CD3+ T cells activate APC, chemoirradiated neutrophils suppress activation of APC in the presence of other activating factors, suggesting that the composition of the ECP-treated buffy coat might be of importance for its immunomodulatory effects.