Effect of gamma radiation on cytokine expression and cytokine-receptor mediated STAT activation

Parotid glands have a dysregulated immune response following radiation therapy

Head and neck cancer treatment often consists of surgical resection of the tumor followed by ionizing radiation (IR), which can damage surrounding tissues and cause adverse side effects. The underlying mechanisms of radiation-induced salivary gland dysfunction are not fully understood, and treatment options are scarce and ineffective. The wound healing process is a necessary response to tissue injury, and broadly consists of inflammatory, proliferative, and redifferentiation phases with immune cells playing key roles in all three phases. In this study, select immune cells were phenotyped and quantified, and certain cytokine and chemokine concentrations were measured in mouse parotid glands after IR. Further, we used a model where glandular function is restored to assess the immune phenotype in a regenerative response. These data suggest that irradiated parotid tissue does not progress through a typical inflammatory response observed in wounds that heal. Specifically, total immune cells (CD45+) decrease at days 2 and 5 following IR, macrophages (F4/80+CD11b+) decrease at day 2 and 5 and increase at day 30, while neutrophils (Ly6G+CD11b+) significantly increase at day 30 following IR. Additionally, radiation treatment reduces CD3- cells at all time points, significantly increases CD3+/CD4+CD8+ double positive cells, and significantly reduces CD3+/CD4-CD8- double negative cells at day 30 after IR. Previous data indicate that post-IR treatment with IGF-1 restores salivary gland function at day 30, and IGF-1 injections attenuate the increase in macrophages, neutrophils, and CD4+CD8+ T cells observed at day 30 following IR. Taken together, these data indicate that parotid salivary tissue exhibits a dysregulated immune response following radiation treatment which may contribute to chronic loss of function phenotype in head and neck cancer survivors.

Cellular RNA and DNA sensing pathways are essential for the dose-dependent response of human monocytes to ionizing radiation

Circulating monocytes are important players of the inflammatory response to ionizing radiation (IR). These IR-resistant immune cells migrate to radiation-damaged tissues and differentiate into macrophages that phagocytize dying cells, but also facilitate inflammation. Besides the effect of damage-associated molecular patterns, released from irradiated tissues, the inflammatory activation of monocytes and macrophages is largely dependent on IR-induced DNA damage and aberrant transcriptional activity, which may facilitate expression of type I interferons (IFN-I) and numerous inflammation-related genes. We analyzed the accumulation of dsRNA, dsDNA fragments, and RNA:DNA hybrids in the context of induction of RNA-triggered MAVS-mediated and DNA-triggered STING-mediated signaling pathways, in primary human monocytes and a monocytic cell line, THP1, in response to various doses of gamma IR. We found that exposure to lower doses (<7.5 Gy) led to the accumulation of dsRNA, along with dsDNA and RNA:DNA hybrids and activated both MAVS and STING pathway-induced gene expression and signaling activity of IFN-I. Higher doses of IR resulted in the reduced dsRNA level, degradation of RNA-sensing mediators involved in MAVS signaling and coincided with an increased accumulation of dsDNA and RNA:DNA hybrids that correlated with elevated STING signaling and NF-κB-dependent gene expression. While both pathways activate IFN-I expression, using MAVS- and STING-knockout THP1 cells, we identified differences in the spectra of interferon-stimulated genes (ISGs) that are associated with each specific signaling pathway and outlined a large group of STING signaling-associated genes. Using the RNAi technique, we found that increasing the dose of IR activates STING signaling through the DNA sensor cGAS, along with suppression of the DDX41 helicase, which is known to reduce the accumulation of RNA:DNA hybrids and thereby limit cGAS/STING signaling activity. Together, these results indicate that depending on the applied dose, IR leads to the activation of either dsRNA-induced MAVS signaling, which predominantly leads to the expression of both pro- and anti-inflammatory markers, or dsDNA-induced STING signaling that contributes to pro-inflammatory activation of the cells. While RNA:DNA hybrids boost both MAVS- and STING-mediated signaling pathways, these structures being accumulated upon high IR doses promote type I interferon expression and appear to be potent enhancers of radiation dose-dependent pro-inflammatory activation of monocytes.

Irradiation and parasitism affect the ability of larval hemocytes of Anastrepha obliqua for phagocytosis and the production of reactive oxygen species

The development of the parasitoid Doryctobracon crawfordi (Viereck) (Hymenoptera: Braconidae) in Anastrepha obliqua (McQuart) (Diptera: Tephritidae) larvae is unviable in nature; however, if the host larva is irradiated at 160 Gy, the parasitoid develops and emerges successfully. This suggests that radiation affects the immune responses of A. obliqua larvae, while the underlying mechanisms remain to be revealed. Using optical and electronic microscopies we determined the number and type of hemocyte populations found inside the A. obliqua larvae, either nonirradiated, irradiated at 160 Gy, parasitized by D. crawfordi, or irradiated and parasitized. Based on flow cytometry, the capacity to produce reactive oxygen species (ROS) was determined by the 123-dihydrorhodamine method in those hemocyte cells. Five cell populations were found in the hemolymph of A. obliqua larvae, two of which (granulocytes and plasmatocytes) can phagocytize and produce ROS. A reduction in the number of cells, mainly of the phagocytic type, was observed, as well as the capacity of these cells to produce ROS, when A. obliqua larvae were irradiated. Both radiation and parasitization decreased the ROS production, and when A. obliqua larvae were irradiated followed by parasitization by D. crawfordi, the reduction of the ROS level was even greater. In contrast, a slight increase in the size of these cells was observed in the hemolymph of the parasitized larvae compared to those in nonparasitized larvae. These results suggest that radiation significantly affects the phagocytic cells of A. obliqua and thus permits the development of the parasitoid D. crawfordi.

Monocyte programming by cancer therapy

Monocytes in peripheral blood circulation are the precursor of essential cells that control tumor progression, that include tumor-associated macrophages (TAMs), dendritic cells (DCs) and myeloid-derive suppressor cells (MDSC). Monocytes-derived cells orchestrate immune reactions in tumor microenvironment that control disease outcome and efficiency of cancer therapy. Four major types of anti-cancer therapy, surgery, radiotherapy, chemotherapy, and most recent immunotherapy, affect tumor-associated macrophage (TAM) polarization and functions. TAMs can also decrease the efficiency of therapy in a tumor-specific way. Monocytes is a major source of TAMs, and are recruited to tumor mass from the blood circulation. However, the mechanisms of monocyte programming in circulation by different therapeutic onsets are only emerging. In our review, we present the state-of-the art about the effects of anti-cancer therapy on monocyte progenitors and their dedifferentiation, on the content of monocyte subpopulations and their transcriptional programs in the circulation, on their recruitment into tumor mass and their potential to give origin for TAMs in tumor-specific microenvironment. We have also summarized very limited available knowledge about genetics that can affect monocyte interaction with cancer therapy, and highlighted the perspectives for the therapeutic targeting of circulating monocytes in cancer patients. We summarized the knowledge about the mediators that affect monocytes fate in all four types of therapies, and we highlighted the perspectives for targeting monocytes to develop combined and minimally invasive anti-cancer therapeutic approaches.

PARADOXICAL DUAL ROLES OF SOME CYTOKINES INTERPRETED BY CYTOGENETICS INVESTIGATIONS IN IRRADIATED HUMAN BLOOD CULTURES

Four different cytokines (IL1-β, IL-6, IL-10 and TNF-α) and the cytokinesis-block micronucleus (CBMN) cytome assay investigations were evaluated in six human blood samples. They were divided into the control (nonirradiated) and five gamma-irradiated groups which were exposed to five different doses (0.5, 1, 2, 4 and 8 Gy). Blood groups were cultured in triplets for 72 h following 1 h of irradiation. Immunological and cytogenetics were investigated parallelly at different irradiation doses to understand the connection between them. Our aim is anchoring the active proliferation action of cytokines by presence of binucleated cells and resting immune system by mononuclear cell. Also, cell death by increasing necrotic cell count and TNF-α concentration. When compared with the control group, 0.5, 1, 2 and 4 Gy irradiation groups recorded a gradual increase in the cytokines levels, an increase in the total micronucleated cells (binucleated and mononucleated cells), an increase in necrotic and apoptotic cells counts. While 8 Gy irradiation leads to depletion in TNF-α concentration, although the number of necrotic cells was high.

Mitigating effects of sublethal and lethal whole-body gamma irradiation in a mouse model with soluble melanin

The field of radiation countermeasures is growing, however, currently there are no effective and non-toxic compounds which could be administered orally to the individuals post exposure to high doses of ionising radiation. The pigment melanin is ubiquitous through all kingdoms of life and provides selective advantage under radiation stress through its role as a chemical and physical shield, and its capacity to respond and react to exposures. Soluble allomelanin was administered to mice following whole-body exposure to lethal or sublethal doses of gamma radiation to determine its capacity to mitigate the effects of acute radiation syndrome, and its utility as a radiation countermeasure. Allomelanin has shown a trend to improve survival post an 8 Gy sublethal radiation exposure when administered up to 48 h post-irradiation. Furthermore, it improved median and overall survival to a 10 Gy lethal radiation exposure, specifically when administered at 24 h post-irradiation. Histological analysis on the jejunum region of the small intestine of this treatment group indicated that alterations of the mucosal and submucosal architecture, and disruption of the lymphatic system associated with lethal radiation exposure were mitigated when allomelanin was administered at 24 h post-irradiation. Based on this work soluble allomelanin derived from a fungal source could serve as an easily sourced, cost-effective, and viable countermeasure to accidental radiation exposure and merits further investigation.

Radiation inducible MafB gene is required for thymic regeneration

The thymus facilitates mature T cell production by providing a suitable stromal microenvironment. This microenvironment is impaired by radiation and aging which lead to immune system disturbances known as thymic involution. Young adult thymus shows thymic recovery after such involution. Although various genes have been reported for thymocytes and thymic epithelial cells in such processes, the roles of stromal transcription factors in these remain incompletely understood. MafB (v-maf musculoaponeurotic fibrosarcoma oncogene homolog B) is a transcription factor expressed in thymic stroma and its expression was induced a day after radiation exposure. Hence, the roles of mesenchymal MafB in the process of thymic regeneration offers an intriguing research topic also for radiation biology. The current study investigated whether MafB plays roles in the adult thymus. MafB/green fluorescent protein knock-in mutant (MafB^+/GFP) mice showed impaired thymic regeneration after the sublethal irradiation, judged by reduced thymus size, total thymocyte number and medullary complexity. Furthermore, IL4 was induced after irradiation and such induction was reduced in mutant mice. The mutants also displayed signs of accelerated age-related thymic involution. Altogether, these results suggest possible functions of MafB in the processes of thymic recovery after irradiation, and maintenance during aging.

How Macrophages Become Transcriptionally Dysregulated: A Hidden Impact of Antitumor Therapy

Tumor-associated macrophages (TAMs) are the essential components of the tumor microenvironment. TAMs originate from blood monocytes and undergo pro- or anti-inflammatory polarization during their life span within the tumor. The balance between macrophage functional populations and the efficacy of their antitumor activities rely on the transcription factors such as STAT1, NF-κB, IRF, and others. These molecular tools are of primary importance, as they contribute to the tumor adaptations and resistance to radio- and chemotherapy and can become important biomarkers for theranostics. Herein, we describe the major transcriptional mechanisms specific for TAM, as well as how radio- and chemotherapy can impact gene transcription and functionality of macrophages, and what are the consequences of the TAM-tumor cooperation.

Gamma-radiated immunosuppressed tumor xenograft mice can be a new ideal model in cancer research

Tumor xenograft models can create a high capacity to study human tumors and discover efficient therapeutic approaches. Here, we aimed to develop the gamma-radiated immunosuppressed (GIS) mice as a new kind of tumor xenograft model for biomedical studies. First, 144 mice were divided into the control and treated groups exposed by a medical Cobalt-60 apparatus in 3, 4, and 5 Gy based on the system outputs. Then, 144 BALB/c mice were divided into four groups; healthy, xenograft, radiation, and radiation + xenograft groups. The animals in the xenograft and radiation + xenograft groups have subcutaneously received 3 × 106 MCF-7 cells 24 h post-radiation. On 3, 7, 14, and 21 days after cell injection, the animals were sacrificed. Then, the blood samples and the spleen and tumor tissues were removed for the cellular and molecular analyses. The whole-body gamma radiation had a high immunosuppressive effect on the BALB/c mice from 1 to 21 days post-radiation. The macroscopic and histopathological observations have proved that the created clusters' tumor structure resulted in the xenograft breast tumor. There was a significant increase in tumor size after cell injection until the end of the study. Except for Treg, the spleen level of CD4, CD8, CD19, and Ly6G was significantly decreased in Xen + Rad compared to the Xen alone group on 3 and 7 days. Unlike IL-4 and IL-10, the spleen level of TGF-β, INF-γ, IL-12, and IL-17 was considerably decreased in the Xen + Rad than the Xen alone group on 3 and 7 days. The spleen expressions of the VEGF, Ki67, and Bax/Bcl-2 ratio were dramatically increased in the Xen + Rad group compared to the Xen alone on 3, 7, 14, and 21 days. Our results could confirm a new tumor xenograft model via an efficient immune-suppressive potential of the whole-body gamma radiation in mice.

Resveratrol Modulates the Inflammatory Profile of Immune Responses and Circulating Endothelial Cells' (CECs') Population During Acute Whole Body Gamma Irradiation

Wistar rats were whole body irradiated with a single dose of 2 Gy post administration with 10 or 100 mg/kg of resveratrol (RSV) intraperitoneally for 30 days. Rats’ livers were dissected and processed to analyze immune response profiles of Th1, Th2, Th9, Th17, and Th22 by flow cytometry. In addition, peripheral blood samples were collected and circulating endothelial cells (CECs) were counted as an indicator for endothelial damage. Results demonstrated that resveratrol at 100 mg/kg enhanced liver immunological response influenced by irradiation by inducing Th2 immune response that was revealed by an increase in IL-10 secretion to more than 5,000 pmol/ml post irradiation. Results also indicated that RSV, at a dose of 100 mg/kg, decreased levels of the main pro-inflammatory cytokines such as INF-γ, IL-22, IL-17A, and GM-CSF post irradiation. In addition, the same RSV was bound to upregulate the expression of IL-10 mRNA in isolated Kupffer cells (KCs) and their secretion of IL-10 post irradiation. The result demonstrated that KCs were the central source of this anti-inflammatory response mediated mainly by IL10. These results, proposed for the first time, clearly states that RSV promotes IL-10 mediated immune resolution by Kupffer cells and not by hepatocytes. This implies that KCs have a crucial role in radiotherapy. Additionally, this study showed that RSV had an anti-apoptotic effect through re-increasing the number of CECs, which is implicated in irradiation damage. Result of the current work discloses novel findings about the potential of RSV as a radio-protector agent of a natural origin and suggests novel roles of KCs as a pharmacological target during radiation exposure.

Irradiation of early immature Anastrepha ludens stages for the rearing of Doryctobracon areolatus (Hymenoptera: Braconidae), a fruit fly parasitoid

Doryctobracon areolatus is a native parasitoid of the Neotropical region that presents the highest percentages of natural parasitism of fruit flies of the genus Anastrepha. In the Moscafrut Program SADER-SENASICA, located in Metapa de Domínguez, Chiapas, Mexico, a laboratory colony of this species is maintained on Anastrepha ludens, the Mexican fruit fly, with the aim to scale the production of the parasitoid up to massive levels. In order to eliminate unwanted emergence of adult flies during the rearing process, this study evaluated the effect of irradiation (at doses of 20, 30, 40, and 50 Gy) applied to eggs, and first and second instar larvae of A. ludens; all irradiated stages were subsequently exposed as second instar larvae to adult females of D. areolatus. Irradiation did not affect the eclosion of A. ludens eggs but, at doses of 40 and 50 Gy, it did cause delayed larval development and pupation, as well as lower larval weight. Adult fly emergence was suppressed at all doses, except in eggs irradiated at 20 Gy. Doses of 20 and 30 Gy applied to the eggs and larvae did not affect the emergence, survival, fecundity or flight ability of the emerged parasitoids, but the second instar larvae were easily handled during the rearing process. Our results suggest that D. areolatus can be successfully produced in second instar larvae of A. ludens irradiated at 30 Gy.

Comparison of Biodosimetry Biomarkers for Radiation Dose and Injury Assessment After Mixed-Field (Neutron and Gamma) and Pure Gamma Radiation in the Mouse Total-Body Irradiation Model

The detonation of a nuclear weapon and the occurrence of a nuclear accident represent possible mass-casualty events with significant exposure to mixed neutron and gamma radiation fields in the first few minutes after the event with the ensuing fallout, extending for miles from the epicenter, that would result primarily in photon (gamma- and/or x-ray) exposure. Circulating biomarkers represent a crucial source of information in a mass-casualty radiation exposure triage scenario. We evaluated multiple blood biodosimetry and organ-specific biomarkers for early-response assessment of radiation exposure using a mouse (B6D2F1, males and females) total-body irradiation model exposed to Co gamma rays over a broad dose range (3-12 Gy) and dose rates of either 0.6 or 1.9 Gy min and compared the results with those obtained after exposure of mice to a mixed field (neutrons and gamma rays) using the Armed Forces Radiobiology Research Institute Co gamma-ray source and TRIGA Mark F nuclear research reactor. The mixed-field studies were performed previously over a broad dose range (1.5-6 Gy), with dose rates of either 0.6 or 1.9 Gy min, and using different proportions of neutrons and gammas: either (67% neutrons + 33% gammas) or (30% neutrons + 70% gammas). Blood was collected 1, 2, 4, and 7 d after total-body irradiation. Results from Co gamma-ray studies demonstrate: (1) significant dose- and time-dependent reductions in circulating mature hematopoietic cells; (2) dose- and time-dependent changes in fms-related tyrosine kinase 3 ligand, interleukins IL-5, IL-10, IL-12, and IL-18, granulocyte colony-stimulating factors, thrombopoietin, erythropoietin, acute-phase proteins (serum amyloid A and lipopolysaccharide binding protein), surface plasma neutrophil (CD45) and lymphocyte (CD27) markers, ratio of CD45 to CD27, procalcitonin but not in intestinal fatty acid binding protein; (3) no significant differences were observed between dose-rate groups in hematological and protein profiles (fms-related tyrosine kinase 3 ligand, IL-5, IL-12, IL-18, erythropoietin, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, CD27, CD45, and ratio of CD45 to CD27) for any radiation dose at any time after exposure (p > 0.148); (4) no significant differences were observed between sex groups in hematological and protein profiles (fms-related tyrosine kinase 3 ligand, IL-18, erythropoietin, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, serum amyloid A, CD45) for any radiation dose at any time after exposure (p > 0.114); and (5) PCT level significantly increased (p < 0.008) in mice irradiated with 12 Gy on day 7 post-total-body irradiation without significant differences between groups irradiated at dose rates of either 0.6 or 1.9 Gy min (p > 0.287). Radiation-quality comparison results demonstrate that: (1) equivalent doses of pure gamma rays and mixed-field radiation do not produce equivalent biological effects, and hematopoietic syndrome occurs at lower doses of mixed-field radiation; (2) ratios of hematological and protein biomarker means in the Co study compared to mixed-field studies using 2× Co doses vs. 1× TRIGA radiation doses (i.e., 3 Gy Co vs. 1.5 Gy TRIGA) ranged from roughly 0.2 to as high as 26.5 but 57% of all ratios fell within 0.7 and 1.3; and (3) in general, biomarker results are in agreement with the relative biological effectiveness = 1.95 (Dn/Dt = 0.67) reported earlier by Armed Forces Radiobiology Research Institute scientists in mouse survival countermeasure studies.

Effect of gamma irradiation doses in the structural and functional properties of mice splenic cells

PURPOSE

Ionizing radiation is nowadays effectively used in cancer treatments. However, the effect of irradiation in immune-system cells is poorly understood and remains controversial. The aim of this work was to determine the effect of γ-irradiation in the structural and functional properties of mice splenic cells.

MATERIALS AND METHODS

Structural traits of irradiated splenic cells were evaluated by Atomic Force Microscopy and Raman spectroscopy. Functional properties were measured by gene and protein expression by RT-qPCR and ELISA, respectively. The induced cytotoxic effect was evaluated by MTT assay and the phagocytic capability by flow cytometry.

RESULTS

Membrane roughness and molecular composition of splenic adherent cells are not changed by irradiation doses exposure. An increase in transcription of pro-inflammatory cytokines was observed. While protein expression decreased in IL-2 dose-dependent, relevant differences were identified in the anti-inflammatory marker IL-10 at 27 Gy. An increase of cytotoxicity in irradiated cells at 7 Gy and 27 Gy doses was observed, while phagocytosis was slight increased at 7 Gy dose but not statistically significant.

CONCLUSIONS

We have demonstrated that γ-irradiation affects the splenic cells and changes the cytokines profile toward a pro-inflammatory phenotype and a tendency to increase the cytotoxicity was found, which implies a stimulation of immune response induced by γ-irradiation.

Radiation, inflammation and the immune response in cancer

Radiation is an important component of cancer treatment with more than half of all patients receive radiotherapy during their cancer experience. While the impact of radiation on tumour morphology is routinely examined in the pre-clinical and clinical setting, the impact of radiation on the tumour microenvironment and more specifically the inflammatory/immune response is less well characterised. Inflammation is a key contributor to short- and long-term cancer eradication, with significant tumour and normal tissue consequences. Therefore, the role of radiation in modulating the inflammatory response is highly topical given the current wave of targeted and immuno-therapeutic treatments for cancer. This review provides a general overview of how radiation modulates the inflammatory and immune response—(i) how radiation induces the inflammatory/immune system, (ii) the cellular changes that take place, (iii) how radiation dose delivery affects the immune response, and (iv) a discussion on research directions to improve patient survival, reduce side effects, improve quality of life, and reduce financial costs in the immediate future. Harnessing the benefits of radiation on the immune response will enhance its maximal therapeutic benefit and reduce radiation-induced toxicity.

Effect of gamma radiation on the expression of mRNA growth factors in glycerol cryopreserved human amniotic membrane

Human amniotic membrane (HAM) due to its high biocompatibility, low immunogenicity, anti-microbial, anti-viral properties as well as the presence of growth factors has been used in various clinical applications. The growth factors play an important role in wound healing. The current study aimed to explore the effect of 15 kGy gamma radiation dose on selected growth factors and receptors mRNA present in HAM. Eight growth factors, namely, EGF, HGF, KGF, TGF-α, TGF-β1, TGF-β2, TGF-β3 and bFGF and two growth factor receptors, HGFR and KGFR were evaluated in this study. The total RNA was extracted and converted to complimentary DNA using commercial kits. Subsequently, the mRNA expressions of these growth factors were evaluated using real-time PCR and the results were statistically analyzed using REST-MCS software. This study confirmed the presence of these mRNA growth factors and receptors in fresh, glycerol cryopreserved and irradiated glycerol cryopreserved HAM. In glycerol cryopreserved HAM, the results showed up-regulation of HGF and bFGF and down-regulation of EGF, HGFR, KGF, KGFR, TGF-α, TGF-β1, TGF-β2 and TGF-β3 relative to the fresh HAM which acted as the control, whereas in irradiated glycerol cryopreserved HAM, the results showed up-regulation of EGF, HGF, KGF, KGFR, TGF-β1, TGF-β2 and TGF-β3 and down-regulation of HGFR, TGF-α and bFGF relative to the glycerol cryopreserved HAM which acted as the control. However, these mRNA expressions did not show any statistical significant difference compared to the control groups. This study concluded that a dose of 15 kGy of gamma radiation did not affect the mRNA expression for the growth factors' and receptors' in the glycerol cryopreserved HAM.

Single Low-Dose Radiation Induced Regulation of Keratinocyte Differentiation in Calcium-Induced HaCaT Cells

Background

We are continually exposed to low-dose radiation (LDR) in the range 0.1 Gy from natural sources, medical devices, nuclear energy plants, and other industrial sources of ionizing radiation. There are three models for the biological mechanism of LDR: the linear no-threshold model, the hormetic model, and the threshold model.

Objective

We used keratinocytes as a model system to investigate the molecular genetic effects of LDR on epidermal cell differentiation.

Methods

To identify keratinocyte differentiation, we performed western blots using a specific antibody for involucrin, which is a precursor protein of the keratinocyte cornified envelope and a marker for keratinocyte terminal differentiation. We also performed quantitative polymerase chain reaction. We examined whether LDR induces changes in involucrin messenger RNA (mRNA) and protein levels in calcium-induced keratinocyte differentiation.

Results

Exposure of HaCaT cells to LDR (0.1 Gy) induced p21 expression. p21 is a key regulator that induces growth arrest and represses stemness, which accelerates keratinocyte differentiation. We correlated involucrin expression with keratinocyte differentiation, and examined the effects of LDR on involucrin levels and keratinocyte development. LDR significantly increased involucrin mRNA and protein levels during calcium-induced keratinocyte differentiation.

Conclusion

These studies provide new evidence for the biological role of LDR, and identify the potential to utilize LDR to regulate or induce keratinocyte differentiation.

Blockage of caspase-1 activation ameliorates bone marrow inflammation in mice after hematopoietic stem cell transplantation

Conditioning regimens before hematopoietic stem cell transplantation (HSCT), cause damage to bone marrow and inflammation. Whether inflammasomes are involved in bone marrow inflammation remains unclear. The study aims to evaluate the role of inflammasomes in bone marrow inflammation after HSCT. On days 7, 14, 21 and 28 after HSCT, mice were sacrificed for analysis of bone marrow inflammation, pro-inflammatory cytokines secretion, inflammasomes expression and caspase-1 activation. Bone marrow inflammation with neutrophils and macrophages infiltration was observed after HSCT. Secretion of IL-1β, IL-18, TNF-α and IL-6 were elevated, with increased caspase-1 activation and inflammasomes expression. Caspase-1 inhibitor administration after HSCT significantly reduced infiltration of neutrophils and macrophages into bone marrow and increased the numbers of megakaryocytes and platelets. In conclusion, inflammasomes activation is involved in bone marrow inflammation after HSCT and caspase-1 inhibition attenuates bone marrow inflammation and promoted hematopoietic reconstitution, suggesting targeting caspase-1 might be beneficial for improving HSCT outcomes.

Portrait of inflammatory response to ionizing radiation treatment

Ionizing radiation (IR) activates both pro-and anti-proliferative signal pathways producing an imbalance in cell fate decision. IR is able to regulate several genes and factors involved in cell-cycle progression, survival and/or cell death, DNA repair and inflammation modulating an intracellular radiation-dependent response. Radiation therapy can modulate anti-tumour immune responses, modifying tumour and its microenvironment. In this review, we report how IR could stimulate inflammatory factors to affect cell fate via multiple pathways, describing their roles on gene expression regulation, fibrosis and invasive processes. Understanding the complex relationship between IR, inflammation and immune responses in cancer, opens up new avenues for radiation research and therapy in order to optimize and personalize radiation therapy treatment for each patient.

Donor satellite cell engraftment is significantly augmented when the host niche is preserved and endogenous satellite cells are incapacitated

Stem cell transplantation is already in clinical practice for certain genetic diseases and is a promising therapy for dystrophic muscle. We used the mdx mouse model of Duchenne muscular dystrophy to investigate the effect of the host satellite cell niche on the contribution of donor muscle stem cells (satellite cells) to muscle regeneration. We found that incapacitation of the host satellite cells and preservation of the muscle niche promote donor satellite cell contribution to muscle regeneration and functional reconstitution of the satellite cell compartment. But, if the host niche is not promptly refilled, or is filled by competent host satellite cells, it becomes nonfunctional and donor engraftment is negligible. Application of this regimen to aged host muscles also promotes efficient regeneration from aged donor satellite cells. In contrast, if the niche is destroyed, yet host satellite cells remain proliferation-competent, donor-derived engraftment is trivial. Thus preservation of the satellite cell niche, concomitant with functional impairment of the majority of satellite cells within dystrophic human muscles, may improve the efficiency of stem cell therapy.

Cytokines in radiobiological responses: a review

Cytokines function in many roles that are highly relevant to radiation research. This review focuses on how cytokines are structurally organized, how they are induced by radiation, and how they orchestrate mesenchymal, epithelial and immune cell interactions in irradiated tissues. Pro-inflammatory cytokines are the major components of immediate early gene programs and as such can be rapidly activated after tissue irradiation. They converge with the effects of ionizing radiation in that both generate free radicals including reactive oxygen and nitrogen species (ROS/RNS). "Self" molecules secreted or released from cells after irradiation feed the same paradigm by signaling for ROS and cytokine production. As a result, multilayered feedback control circuits can be generated that perpetuate the radiation tissue damage response. The pro-inflammatory phase persists until such times as perceived challenges to host integrity are eliminated. Antioxidant, anti-inflammatory cytokines then act to restore homeostasis. The balance between pro-inflammatory and anti-inflammatory forces may shift to and fro for a long time after radiation exposure, creating waves as the host tries to deal with persisting pathogenesis. Individual cytokines function within socially interconnected groups to direct these integrated cellular responses. They hunt in packs and form complex cytokine networks that are nested within each other so as to form mutually reinforcing or antagonistic forces. This yin-yang balance appears to have redox as a fulcrum. Because of their social organization, cytokines appear to have a considerable degree of redundancy and it follows that an elevated level of a specific cytokine in a disease situation or after irradiation does not necessarily implicate it causally in pathogenesis. In spite of this, "driver" cytokines are emerging in pathogenic situations that can clearly be targeted for therapeutic benefit, including in radiation settings. Cytokines can greatly affect intrinsic cellular radiosensitivity, the incidence and type of radiation tissue complications, bystander effects, genomic instability and cancer. Minor and not so minor, polymorphisms in cytokine genes give considerable diversity within populations and are relevant to causation of disease. Therapeutic intervention is made difficult by such complexity; but the potential prize is great.

Effects of ionizing radiation on the immune system with special emphasis on the interaction of dendritic and T cells

Dendritic cells (DCs), as professional antigen-presenting cells, are members of the innate immune system and function as key players during the induction phase of adaptive immune responses. Uptake, processing, and presentation of antigens direct the outcome toward either tolerance or immunity. The cells of the immune system are among the most highly radiosensitive cells in the body. For high doses of ionizing radiation (HD-IR) both immune-suppressive effects after whole body irradiation and possible immune activation during tumor therapy were observed. On the other hand, the effects of low doses of ionizing radiation (LD-IR) on the immune system are controversial and seem to show high variability among different individuals and species. There are reports revealing that protracted LD-IR can result in radioresistance. But immune-suppressive effects of chronic LD-IR are also reported, including the killing or sensitizing of certain cell types. This article shall review the current knowledge of radiation-induced effects on the immune system, paying special attention to the interaction of DCs and T cells.

Long-term alterations of cytokines and growth factors expression in irradiated tissues and relation with histological severity scoring

Purpose

Beside its efficacy in cancer treatment, radiotherapy induces degeneration of healthy tissues within the irradiated area. The aim of this study was to analyze the variations of proinflammatory (IL-1α, IL-2, IL-6, TNF-α, IFN-γ), profibrotic (TGF-β1), proangiogneic (VEGF) and stem cell mobilizing (GM-CSF) cytokines and growth factors in an animal model of radiation-induced tissue degeneration.

Materials and Methods

24 rats were irradiated unilaterally on the hindlimb at a monodose of 30 Gy. Six weeks (n = 8), 6 months (n = 8) and 1 year (n = 8) after irradiation the mediators expression in skin and muscle were analyzed using Western blot and the Bio-Plex® protein array (BPA) technology. Additional histological severity for fibrosis, inflammation, vascularity and cellularity alterations scoring was defined from histology and immnunohistochemistry analyses.

Results

A significant increase of histological severity scoring was found in irradiated tissue. Skin tissues were more radio-sensitive than muscle. A high level of TGF-β1 expression was found throughout the study and a significant relation was evidenced between TGF-β1 expression and fibrosis scoring. Irradiated tissue showed a chronic inflammation (IL-2 and TNF-α significantly increased). Moreover a persistent expression of GM-CSF and VEGF was found in all irradiated tissues. The vascular score was related to TGF-β1 expression and the cellular alterations score was significantly related with the level of IL-2, VEGF and GM-CSF.

Conclusion

The results achieved in the present study underline the complexity and multiplicity of radio-induced alterations of cytokine network. It offers many perspectives of development, for the comprehension of the mechanisms of late injuries or for the histological and molecular evaluation of the mode of action and the efficacy of rehabilitation techniques.

Low-dose gamma-rays and simulated solar particle event protons modify splenocyte gene and cytokine expression patterns

The goal was to investigate the T helper (Th) response in splenocytes of mice exposed to low-dose/low-dose-rate (LDR) γ-rays, simulated solar particle event protons (sSPE), or combination of both. C57BL/6 mice were exposed to LDR γ-radiation ((57)Co) to a total dose of 0.05 Gray (Gy) at 0.024 cGy/h, either with or without subsequent exposure to 2 Gy sSPE protons. Expression of genes related to Th cells was evaluated immediately after exposure (day 0). On day 21, intra- and extracellular cytokine production was assessed after activation with anti-CD3 monoclonal antibodies (mAb) or phorbol 12-myristate 13-acetate/ionophore (PMA/I). Five genes were significantly modulated on day 0 in one or more of the irradiated groups compared to controls (p < 0.05): Ccl11, Ccr5, Cd80, Inha, and Il9. On day 21, numbers of cells positive for interferon-γ were high in the LDR + sSPE group versus 0 Gy and LDR γ-rays (p < 0.05), but there was no difference in IL-2 and TNF-α. Levels of secreted cytokines after anti-CD3 mAb activation were high for 5 (MIP-1α, GM-CSF, IFN-γ, TNF-α, IL-13) and low for 2 (IL-7, IL-9) in all irradiated groups. Priming with LDR photons had a significant effect on IFN-γ and IL-17 compared to sSPE protons alone; IL-2 was low only in the LDR + sSPE group. The cytokine patterns after anti-PMA/I activation were different compared to anti-CD3 mAb and with fewer differences among groups. The data show that total-body exposure to space-relevant radiation has profound effects on Th cell status and that priming with LDR γ-rays can in some cases modulate the response to sSPE.

Low-dose γ-rays modify CD4(+) T cell signalling response to simulated solar particle event protons in a mouse model

PURPOSE

Astronauts on missions are exposed to low-dose/low-dose-rate (LDR) radiation and could receive high doses during solar particle events (SPE). This study investigated T cell function in response to LDR radiation and simulated SPE (sSPE) protons, alone and in combination.

MATERIALS AND METHODS

C57BL/6 mice received LDR γ-radiation (⁵⁷Co) to a total dose of 0.01 Gray (Gy) at 0.179 mGy/h, either with or without subsequent exposure to 1.7 Gy sSPE protons delivered over 36 h. Mice were euthanised on days 4 and 21 post-exposure. T cells with cluster of differentiation 4 (CD4(+)) were negatively isolated from spleens and activated with anti-CD3 antibody. Cells and supernatants were evaluated for survival/signalling proteins and cytokines.

RESULTS

The most striking effects were noted on day 21. In the survival pathway, nuclear factor-kappaB (NF-κB; total and active forms) and p38 mitogen activated protein kinase (p38MAPK; total) were significantly increased and cJun N-terminal kinase (JNK; total and active) was decreased when mice were primed with LDR γ-rays prior to sSPE exposure (P < 0.001). Evaluation of the T cell antigen receptor (TCR) signalling pathway revealed that LDR γ-ray exposure normalised the high sSPE proton-induced level of lymphocyte specific protein tyrosine kinase (Lck; total and active) on day 21 (P < 0.001 for sSPE vs. LDR + sSPE), while radiation had no effect on active zeta-chain-associated protein kinase 70 (Zap-70). There was increased production of interleukin-2 (IL-2) and IL-4 and decreased transforming growth factor-β1 in the LDR + sSPE group compared to the sSPE group.

CONCLUSION

The data demonstrate, for the first time, that protracted exposure to LDR γ-rays can significantly modify the effects of sSPE protons on critical survival/signalling proteins and immunomodulatory cytokines produced by CD4(+) T cells.

Influence of sublethal total-body irradiation on immune cell populations in the intestinal mucosa

The intestinal immune system is the largest in the body. This study analyzed changes in intestinal immune cell populations, cytokine protein levels, and transcript profiles after total-body irradiation (TBI) in CD2F1 mice. A single dose of 8.0 Gy gamma radiation caused negligible 30-day lethality but induced significant histological damage in jejunal mucosa that was maximal at 3.5 days and that had seemingly recovered by day 21 after irradiation. These changes were accompanied by decreased numbers of mucosal macrophages, neutrophils, and B and T lymphocytes, mostly coinciding with similar reductions in peripheral blood cell counts. Recovery of mucosal macrophages occurred within 1 week, whereas mucosal granulocytes and lymphocytes remained low until 3 weeks after TBI. Maximal suppression of T-helper cell (T(H))-related transcripts occurred at 3.5 days, but there was no obvious T(H)1 or T(H)2 bias. Genome-wide transcriptional profiling revealed a preponderance of differentially regulated genes involved in cell cycle control, cell death and DNA repair between 4 h and 3.5 days after irradiation. Genes involved in tissue recovery predominated from day 7 onward. We conclude that the intestinal immune system undergoes profound changes after sublethal TBI and that these changes likely contribute to postirradiation pathophysiological manifestations.

Irradiation induces regionally specific alterations in pro-inflammatory environments in rat brain

PURPOSE

Pro-inflammatory environments in the brain have been implicated in the onset and progression of neurological disorders. In the present study, we investigate the hypothesis that brain irradiation induces regionally specific alterations in cytokine gene and protein expression.

MATERIALS AND METHODS

Four month old F344 x BN rats received either whole brain irradiation with a single dose of 10 Gy gamma-rays or sham-irradiation, and were maintained for 4, 8, and 24 h following irradiation. The mRNA and protein expression levels of pro-inflammatory mediators were analysed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining. To elucidate the molecular mechanisms of irradiation-induced brain inflammation, effects of irradiation on the DNA-binding activity of pro-inflammatory transcription factors were also examined.

RESULTS

A significant and marked up-regulation of mRNA and protein expression of pro-inflammatory mediators, including tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and monocyte chemoattractant protein-1 (MCP-1), was observed in hippocampal and cortical regions isolated from irradiated brain. Cytokine expression was regionally specific since TNF-alpha levels were significantly elevated in cortex compared to hippocampus (57% greater) and IL-1beta levels were elevated in hippocampus compared to cortical samples (126% greater). Increases in cytokine levels also were observed after irradiation of mouse BV-2 microglial cells. A series of electrophoretic mobility shift assays (EMSA) demonstrated that irradiation significantly increased activation of activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), and cAMP response element-binding protein (CREB).

CONCLUSION

The present study demonstrated that whole brain irradiation induces regionally specific pro-inflammatory environments through activation of AP-1, NF-kappaB, and CREB and overexpression of TNF-alpha, IL-1beta, and MCP-1 in rat brain and may contribute to unique pathways for the radiation-induced impairments in tissue function.

PPARs in Irradiation-Induced Gastrointestinal Toxicity

The use of radiation therapy to treat cancer inevitably involves exposure of normal tissues. Although the benefits of this treatment are well established, many patients experience distressing complications due to injury to normal tissue. These side effects are related to inflammatory processes, and they decrease therapeutic benefit by increasing the overall treatment time. Emerging evidence indicates that PPARs and their ligands are important in the modulation of immune and inflammatory reactions. This paper discusses the effects of abdominal irradiation on PPARs, their role and functions in irradiation toxicity, and the possibility of using their ligands for radioprotection.

Acute and persisting Th2-like immune response after fractionated colorectal γ-irradiation

AIM: To investigate if an immune imbalance may account for the development and progression of chronic radiation enteritis. We analyzed the Th1/Th2 immune response profile early and 6 mo after fractionated colorectal irradiation.

METHODS: A rat model of fractionated colorectal γ-irradiation (4-Gy fractions, 3 fractions per week) was designed to investigate the effects of cumulative dose on inflammatory mediators (cytokines and chemokines) and immune response (Th1/Th2 profile and immunosuppressive mediator IL-10) during acute (early) response and 6 mo after the end of fractionated irradiation (chronic response). Analyses were performed 1 d after the cumulative doses of 16 Gy and 36 Gy and 1 d, 3 d, and 26 wk after the cumulative dose of 52 Gy.

RESULTS: Without causing histological damage, fractionated radiation induced elevated expression of IL-1β, TNFα, MCP-1, and iNOS in distal colonic mucosa during the early post-irradiation phase. At that time, a Th2 profile was confirmed by expression of both the Th2-specific transcription factor GATA-3 and the chemokine receptor CCR4 and by suppression of the Th1 cytokine IFNγ/IP-10 throughout the irradiation protocol. After 6 mo, despite the 2-fold reduction of iNOS and MCP-1 levels, the Th2 profile persisted, as shown by a 50% reduction in the expression of the Th1 transcription factor T-bet, the chemokine receptor CCXCR3, and the IFNγ/STAT1 pathway. At the same time-point, the immunosuppressive IL-10/STAT3 pathway, known to regulate the Th1/Th2 balance, was expressed, in irradiated rats, at approximately half its level as compared to controls. This suppression was associated with an overexpression of SOCS3, which inhibits the feedback of the Th1 polarization and regulates IL-10 production.

CONCLUSION: Colorectal irradiation induces Th2 polarization, defective IL-10/STAT3 pathway activation and SOCS3 overexpression. These changes, in turn, maintain a immunological imbalance that persists in the long term.

Cross-talk between myeloid-derived suppressor cells and macrophages subverts tumor immunity toward a type 2 response

Although the immune system has the potential to protect against malignancies, many individuals with cancer are immunosuppressed. Myeloid-derived suppressor cells (MDSC) are elevated in many patients and animals with tumors, and contribute to immune suppression by blocking CD4(+) and CD8(+) T cell activation. Using the spontaneously metastatic 4T1 mouse mammary carcinoma, we now demonstrate that cross-talk between MDSC and macrophages further subverts tumor immunity by increasing MDSC production of IL-10, and by decreasing macrophage production of IL-12. Cross-talk between MDSC and macrophages requires cell-cell contact, and the IL-12 decrease is dependent on MDSC production of IL-10. Treatment with the chemotherapeutic drug gemcitabine, which reduces MDSC, promotes rejection of established metastatic disease in IL-4Ralpha(-/-) mice that produce M1 macrophages by allowing T cell activation, by maintaining macrophage production of IL-12, and by preventing increased production of IL-10. Therefore, MDSC impair tumor immunity by suppressing T cell activation and by interacting with macrophages to increase IL-10 and decrease IL-12 production, thereby promoting a tumor-promoting type 2 response, a process that can be partially reversed by gemcitabine.