p53-dependent X-ray-induced modulation of cytokine mRNA levels in vivo

Role of radiation-induced granulocyte colony-stimulating factor in recovery from whole body gamma-irradiation

The purpose of this study was to further elucidate the radioprotective role of granulocyte colony-stimulating factor (G-CSF) induced in response to irradiation. The induction of G-CSF and interleukin-6 (IL-6) in response to radiation exposure was evaluated in mice. The level of cytokine in serum was determined by multiplex Luminex. The role of G-CSF on survival and tissue injury after total body gamma-irradiation was evaluated by administration of neutralizing antibody to G-CSF before radiation exposure. An isotype control was used for comparison and survival was monitored for 30 d after irradiation. Jejunum samples were used for immunohistochemistry. Ionizing radiation exposure induced significant levels of the hematopoietic cytokines G-CSF and IL-6, in mice receiving 9.2 Gy radiation. Maximal levels of G-CSF were observed in peripheral blood of mice 8h after irradiation. IL-6 levels were maximum at 12h after irradiation. Administration of G-CSF antibody significantly enhanced mortality in irradiated mice. G-CSF antibody-treated mice had higher numbers of CD68(+) cells and apoptotic cells in intestinal villi. Our results confirm that radiation exposure induces elevations of circulating G-CSF and IL-6. Neutralizing antibody to G-CSF exacerbates the deleterious effects of radiation, indicating that G-CSF induced in response to irradiation plays an important role in recovery.

Proteomics analysis of apoptosis-regulating proteins in tissues with different radiosensitivity

The aim of this study was to identify of radiosusceptibility proteins in tissues with different radiosensitivity. C3H/HeJ mice were exposed to 10 Gy. The tissues were processed for proteins extraction and were analyzed by 2-dimensional electrophoresis. The proteins were identified by matrix-assisted laser desorption ionizing time-of-flight mass spectrometry and validated by immunohistochemical staining and Western blotting. The peaks of apoptosis levels were 35.3 +/- 1.7% and 0.6 +/- 0.2% in the spleen and the liver, respectively, after ionizing radiation. Analysis of liver tissue showed that the expression level of ROS related proteins such as cytochrome c, glutathione S transferase, NADH dehydrogenase and peroxiredoxin VI increased after radiation. The expression level of cytochrome c increased to 3-fold after ionizing radiation in both tissues. However in spleen tissue, the expression level of various kinds of apoptosis regulating proteins increased after radiation. These involved iodothyronine, CD 59A glycoprotein precursor, fas antigen and tumor necrosis factor -inducible protein TSG-6n precursor after radiation. The difference in the apoptosis index between the liver and spleen tissues is closely associated with the expression of various kinds of apoptosis-related proteins. The result suggests that the expression of apoptosis-related protein and redox proteins play important roles in this radiosusceptibility.

A proteomic analysis of murine bone marrow and its response to ionizing radiation

To characterize the mouse bone marrow tissue proteome and investigate the response to radiation damage we took bone marrow before and after 4-Gy gamma-irradiation from mouse strains (C57BL/6 and CBA/Ca) that differ in their short-term and long-term radiation responses and analyzed extracellular proteins by high-resolution 2-DE. Twenty proteins were identified from 71 protein spots in both C57BL/6 and CBA/Ca. We detected significant differences between control and irradiated bone marrow and between genotypes and identified many of the changed proteins by MS. In C57BL/6, 27 spots were significantly different between control and irradiated samples. In CBA/Ca, 18 spots showed significant changes following irradiation. Proteins such as serum albumin, apolipoprotein A-I, ferritin, haptoglobin (Hp) and alpha-1-antitrypsin were changed in irradiated bone marrow of both mouse strains, reflecting an ongoing acute-phase reaction. Several other proteins including serotransferrin, neutrophil collagenase, peroxiredoxin 2 and creatine kinase M chain were changed specifically in an individual mouse strain. The proteomic approach makes an important contribution to characterizing bone marrow proteome and investigating the tissue response of bone marrow to radiation, assists in identifying genotype-dependent responses and provides support for the importance of microenvironmental factors contributing to the overall response.

Acute vasculitis after endovascular brachytherapy

PURPOSE

Angioplasty effectively relieves coronary artery stenosis but is often followed by restenosis. Endovascular radiation (beta or gamma) at the time of angioplasty prevents restenosis in a large proportion of vessels in swine (short term) and humans (short and long term). Little information is available about the effects of this radiation exposure beyond the wall of the coronary arteries.

METHODS AND MATERIALS

Samples were obtained from 76 minipigs in the course of several experiments designed to evaluate endovascular brachytherapy: 76 of 114 coronary arteries and 6 of 12 iliac arteries were exposed to endovascular radiation from 32P sources (35 Gy at 0.5 mm from the intima). Two-thirds of the vessels had angioplasty or stenting. The vessels were systematically examined either at 28 days or at 6 months after radiation.

RESULTS

We found an unexpected lesion: acute necrotizing vasculitis in arterioles located < or =2.05 mm from the target artery. It was characterized by fibrinoid necrosis of the wall, often associated with lymphocytic exudates or thrombosis. Based on the review of perpendicular sections of tissue samples, the arterioles had received between 6 and 40 Gy. This arteriolar vasculitis occurred at 28 days in samples from 51% of irradiated coronary arteries and 100% of irradiated iliac arteries. By 6 months, the incidence of acute vasculitis decreased to 24% around the coronary arteries. However, at that time, healing vasculitis was evident, often with luminal narrowing, in 46% of samples. Vasculitis was not seen in any of 44 samples from unirradiated vessels (0%) and had no relation to angioplasty, stenting, or their sequelae. This radiation-associated vasculitis in the swine resembles the localized lymphocytic vasculitis that we have reported in tissues of humans exposed to external radiation. On the other hand, it is quite different from the various types of systemic vasculitis that occur in nonirradiated humans.

CONCLUSION

Endoarterial brachytherapy using 32P results in vascular effects beyond the adventitia of the target vessel. This necrotizing vasculitis is causally related to radiation, but its mechanism is unclear and a dose effect is not evident. Quite possibly, local upregulation of inflammatory cytokines contributes to this radiation-associated vasculitis, which only involved some of the arterioles in each sample. It is likely that radiation-associated vasculitis also occurs around human coronary arteries and may result in foci of ischemia. To our knowledge, this lesion has not been previously recognized, either in experimental models or in human specimens examined after angioplasty/brachytherapy.

Allelic loss on chromosome 4 (Lyr2/TLSR5) is associated with myeloid, B-lympho-myeloid, and lymphoid (B and T) mouse radiation-induced leukemias

The CBA/H mouse model of radiation-induced acute myeloid leukemia (AML) was re-examined using molecular approaches. In addition to the typical promyelocytic AMLs, 34% were reclassified as early pre-B lympho-myeloid leukemias (L-ML) based on leukemic blood cell morphology, immunoglobulin heavy-chain gene re-arrangements (IgH(R)), or expression of both lymphoid (Vpre-B1 and Rag1) and myeloid (myeloperoxidase and lysozyme M) genes. Allelic loss on chromosome 4 was frequently detected in AMLs (53%) and L-MLs (more than 95%), and the preferential loss of the maternally transmitted allele suggests the locus may be imprinted. A minimally deleted region (MDR) maps to a 3.4-cM interval, which is frequently deleted in radiation-induced thymic lymphomas (TLSR5) and contains a recessive, maternally transmitted genetic locus (Lyr2) that confers resistance to spontaneous and radiation-induced pre-B and T cell lymphomas, suggesting they are one and the same. Thus, the Lyr2/TLSR5 locus is frequently implicated in myeloid, lymphoid (B and T), and mixed-lineage mouse leukemias and lymphomas. Epigenetic inactivation of one Lyr2/TLSR5 allele during normal mouse development suggests that only a single hit is required for its inactivation during leukemogenesis, and this may be a significant contributing factor to the efficiency of the leukemogenic process in the mouse.

Transforming growth factor-beta inhibits lymphokine activated killer cytotoxicity of bone marrow cells: implications for the graft-versus-leukemia effect in irradiation allogeneic bone marrow chimeras

BACKGROUND

We have previously shown that allogeneic bone marrow (BM) chimeras preconditioned with total lymphoid irradiation and low-dose total body irradiation (TLI/TBI) develop a stronger graft-versus-leukemia (GVL) effect than chimeras preconditioned with high-dose total body irradiation only (TBI). Here, we report on the possible role of cytokines in the mechanism underlying this GVL effect.

METHODS

Splenic mRNA levels of the cytokines interleukin (IL)-1, IL-2, IL-4, IL-6, IL-7, IL-10, IL-12, IL-15, interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta (TGF-beta), and of inducible nitric oxide synthetase were determined by reverse transcription-polymerase chain reaction in TLI/TBI- or TBI-conditioned C3H/AKR BM chimeras challenged with AKR-type BW5147.3 leukemia cells. Ex vivo TGF-beta protein production by splenocytes was determined using ELISA. The possibility that cytokines influence the GVL effect by modulating the activity of IL-2-activated lymphocytes (LAK cells) was investigated by in vitro assays on donor-type BM cells.

RESULTS

Of all cytokine mRNA levels studied, those of TGF-beta and IL-7 were different between groups; both were significantly more elevated in TBI- than in TLI/ TBI-conditioned or normal mice. Differences were apparent after conditioning and were not influenced by additionally injected BM or leukemia cells. Cultured splenocytes of TBI-conditioned animals produced significantly more TGF-beta protein than those of TLI/TBI-conditioned ones or normal controls. r-TGF-beta but not r-IL-7 suppressed in vitro LAK activity of donor-type BM cells against BW5147.3 cells in a dose-dependent way.

CONCLUSIONS

High-dose TBI-induced, host-derived splenic TGF-beta may inhibit generation of LAK cells from subsequently transplanted donor BM cells, suppressing their capacity to generate cytotoxicity upon injection of leukemia cells. The cytokine profile, induced by irradiation in host hematopoietic organs, can significantly modify posttransplant immunological processes such as the GVL effect and graft-versus-host disease (GVHD).