Radiation damage and immune suppression in splenic mononuclear cell populations

We have examined alterations in all of the major splenic mononuclear cell (SMNC) populations in C57B1/6 mice following whole-body irradiation (0-700 cGy) in order to determine which populations may play a role in active immune suppression and/or haematopoietic recovery. A protocol has been established for characterization and differentiation by flow cytometric analysis (FCA) of the major MNC populations in the mouse spleen: T lymphocytes (CD4+ and CD8+ cells), B lymphocytes, natural killer (NK) cells, and monocytes/macrophages. Ionizing radiation caused decreased spleen cellularity and decreased ability of surviving SMNC to respond to mitogen. FCA revealed alterations in the relative composition of the constituent splenic cell populations following irradiation, reflecting differential radiosensitivity, with selective enrichment of NK cells (seven-fold) and CD4+ T lymphocytes (three-fold). Enrichment developed during the 7-day post-irradiation period. In addition, some MNC became activated in a dose- and time-dependent fashion following whole-body irradiation, as indicated by expression of CD71, the transferrin receptor. These cells were CD34+ and Thy 1.2+, but were CD4- or CD8- as well as CD45- (B cell). The observed increase in NK cells corresponds with a previously reported increase in natural suppressor (NS) cells following total-lymphoid irradiation (TLI). The balance of recovery-inhibiting NK cells and recovery-enhancing CD4+ T lymphocytes following irradiation may reflect or influence the degree of haematopoietic recovery, and may provide an indication of the extent of damage (biological dosimetry).

Analysis of immune cell populations and cytokine profiles in murine splenocytes exposed to whole-body low-dose irradiation

PURPOSE

In contrast to high-dose therapeutic irradiation, definitive research detailing the physiological effects of low-dose irradiation is limited. Notably, the immunological response elicited after low-dose irradiation remains controversial.

MATERIALS AND METHODS

Female C57BL/6 mice were whole- body-irradiated with a single or three daily fractions up to a total dose of 0.1, 1, or 10 cGy. Blood and spleen were harvested 2, 7 and 14 days after irradiation.

RESULTS

The splenic CD4(+) T cell subpopulations were temporarily increased at 2 days after single or fractionated irradiation, whereas the percentage of dendritic cells (DC) and macrophages was decreased. Whereas CD8(+) T cell populations were decreased in single-dose irradiated mice at day 7, early and sustained reduction of CD8(+) T cell numbers was observed in fractionated- dose-irradiated mice from day 2 until day 14. In addition, single-dose irradiation resulted in a Th1 cytokine expression profile, whereas fractionated-dose irradiation drove a Th2 shift. Additionally, increased expression of immune-related factors was observed at early time-points with single-dose irradiation, in contrast to the dose-independent induction following fractionated-dose irradiation.

CONCLUSIONS

Our results demonstrate that low-dose irradiation modulates the immune response in mice, where the sensitivity and kinetics of the induced response vary according to the dosing method.

Leydig cell failure with testicular radiation doses <20Gy: The clinical effects of total body irradiation conditioned haematopoietic stem cell transplantation for childhood leukaemia during long-term follow-up

OBJECTIVE

Testosterone replacement is generally considered likely to be required only at testicular radiation doses in excess of 20Gy. Long-term data are not available for patients receiving 9-14.4Gy as part of Total Body Irradiation in childhood.

DESIGN

Retrospective cohort study.

DATA COLLECTION

notes review, laboratory results, prescription of testosterone.

PATIENTS

Forty-two of 96 boys who received Total Body Irradiation (9-14.4Gy) and Haematopoietic Stem Cell Transplantation for childhood leukaemia at Great Ormond Street Hospital between 1981-2011 and survived >5 years.

MEASUREMENTS

The serum concentrations of testosterone and gonadotrophins and the prescription of testosterone were recorded.

RESULTS

Of the 42 boys included, 37 (88%) entered puberty spontaneously and 5 required induction. Median length of follow-up was 19.4 years (range 5-33.1). At last follow-up, 23 of the 37 (62%) with spontaneous puberty were receiving testosterone replacement and 4 of the 5 (80%) with induced puberty.

CONCLUSION

This study with the benefit of long follow-up indicates that Leydig cell failure occurs with radiation doses <20Gy. It may occur many years after irradiation and mandates long-term screening for hypogonadism.

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

Shielded Cs irradiators are routinely used in pre-clinical radiation research to perform in vitro or in vivo investigations. Without appropriate dosimetry and irradiation protocols in place, there can be large uncertainty in the delivered dose of radiation between irradiated subjects that could lead to inaccurate and possibly misleading results. Here, a dosimetric evaluation of the JL Shepard Mark I-68A Cs irradiator and an irradiation technique for whole-body irradiation of small animals that allows one to limit the between subject variation in delivered dose to ±3% are provided. Mathematical simulation techniques and Gafchromic EBT film were used to describe the region within the irradiation cavity with homogeneous dose distribution (100% ± 5%), the dosimetric impact of varying source-to-subject distance, and the variation in attenuation thickness due to turntable rotation. Furthermore, an irradiation protocol and dosimetry formalism that allows calculation of irradiation time for whole-body irradiation of small animals is proposed that is designed to ensure a more consistent dose delivery between irradiated subjects. To compare this protocol with the conventional irradiation protocol suggested by the vendor, high-resolution film dosimetry measurements evaluating the dose difference between irradiation subjects and the dose distribution throughout subjects was performed using phantoms resembling small animals. Based on these results, there can be considerable variation in the delivered dose of > ± 5% using the conventional irradiation protocol for whole-body irradiation doses below 5 Gy. Using the proposed irradiation protocol this variability can be reduced to within ±3% and the dosimetry formalism allows for more accurate calculation of the irradiation time in relation to the intended prescription dose.

Different but synergistic effects of bone marrow-derived VEGFR2+ and VEGFR2-CD45+ cells during hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-associated mortality worldwide in men. Bone marrow-derived cells (BMDCs), including circulating endothelial progenitor cells, have been reported to be involved in the progression of HCC. The complexity of BMDCs inspires further interest in the study of HCC. In the present study, highly metastatic HCC models with BM function deficiency/reconstruction were established by sublethal irradiation/BM transplantation. The effects of vascular endothelial growth factor receptor-2 (VEGFR2)⁺ or VEGFR2⁻/cluster of differentiation 45 (CD45)⁺ BMDCs on HCC growth were evaluated. VEGFR2⁺ and VEGFR2⁻CD45⁺ BMDCs facilitated the recovery of BM function and promoted tumor growth, while the enhancement of tumor growth by VEGFR2⁻CD45⁺ BMDCs was independent of VEGFR2⁺ BMDCs. BM-derived CD45⁺CD133⁺ and VEGFR2⁺CD133⁺ cells synergistically played a role in the different stages during HCC progression. In conclusion, different types of BMDCs exhibit effects on HCC tumor growth in a coordinated manner.

Low-Energy Laser-Driven Ultrashort Pulsed Electron Beam Irradiation-Induced Immune Response in Rats

The development of new laser-driven electron linear accelerators, providing unique ultrashort pulsed electron beams (UPEBs) with low repetition rates, opens new opportunities for radiotherapy and new fronts for radiobiological research in general. Considering the growing interest in the application of UPEBs in radiation biology and medicine, the aim of this study was to reveal the changes in immune system in response to low-energy laser-driven UPEB whole-body irradiation in rodents. Forty male albino Wistar rats were exposed to laser-driven UPEB irradiation, after which different immunological parameters were studied on the 1st, 3rd, 7th, 14th, and 28th day after irradiation. According to the results, this type of irradiation induces alterations in the rat immune system, particularly by increasing the production of pro- and anti-inflammatory cytokines and elevating the DNA damage rate. Moreover, such an immune response reaches its maximal levels on the third day after laser-driven UPEB whole-body irradiation, showing partial recovery on subsequent days with a total recovery on the 28th day. The results of this study provide valuable insight into the effect of laser-driven UPEB whole-body irradiation on the immune system of the animals and support further animal experiments on the role of this novel type of irradiation.

TGF-B3 Dependent Modification of Radiosensitivity in Reporter Cells Exposed to Serum From Whole-Body Low Dose-Rate Irradiated Mice

Prior findings in vitro of a TGF-β3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-β3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation.

Pediatric hormonal disturbances after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for various malignant and nonmalignant diseases. Improvement of HSCT in children has resulted in many long-term survivors with substantial long-term morbidities. Endocrine complications are most frequently observed as late effects in HSCT recipients. Growth failure, pubertal disorders, thyroid dysfunctions, obesity, metabolic syndrome and bone loss are usually encountered after HSCT in children, while infertility is an important problem in adulthood. Patient age at HSCT, characteristics of primary diseases, intervention duration, preparative conditioning regimens, dose of irradiation and specificity of chemotherapeutic agents affect the prevalence of endocrine late effects. Awareness of endocrine late effects of HSCT and close follow-up of patients would help to increase the quality of health of patients.

Effects of radiation based on whole-body irradiation in HTLV-1-infected mice

Adult T-cell leukemia is one of the life-threatening diseases that occur in individuals infected with human T-cell leukemia virus type 1 (HTLV-1). Clinical trials of hematopoietic stem cell transplantation therapy are being performed in addition to chemotherapy; however, neither is satisfactory. As a pretreatment for transplantation, anticancer drugs or whole-body irradiation is used to decrease the number of HTLV-1-infected cells, but there are numerous side effects. Therefore, in the present study, using a mouse model of HTLV-1 infection, the long-term survival and number of infected cells in the reservoir organ were investigated in order to determine the effect of γ-irradiation on HTLV-1-infected mice in vivo. There was no improvement in the survival period following γ-irradiation in the γ-irradiated group after HTLV-1 infection when compared with the HTLV-1-infected group. It was also found that the incidence of splenomegaly was ≥80% in the HTLV-1-infected and γ-irradiated group, which was significantly higher than that in the HTLV-1-infected mice. The tissue morphology in the spleen became non-uniform because of γ-rays. Importantly, the number of infected cells in the spleen was increased 4.1-fold in the HTLV-1-infected and γ-irradiated mice compared with that in the HTLV-1-infected mice. Careful consideration might be necessary when using whole-body irradiation in patients with HTLV-1 infection.

Distinct Urinary Metabolite Signatures Mirror In Vivo Oxidative Stress-Related Radiation Responses in Mice

Exposure to ionizing radiation disrupts metabolic pathways and causes oxidative stress, which can lead to organ damage. In this study, urinary metabolites from mice exposed to high-dose and low-dose whole-body irradiation (WBI HDR, WBI LDR) or partial-body irradiation (PBI BM2.5) were analyzed using targeted and untargeted metabolomics approaches. Significant metabolic changes particularly in oxidative stress pathways were observed on Day 2 post-radiation. By Day 30, the WBI HDR group showed persistent metabolic dysregulation, while the WBI LDR and PBI BM2.5 groups were similar to control mice. Machine learning models identified metabolites that were predictive of the type of radiation exposure with high accuracy, highlighting their potential use as biomarkers for radiation damage and oxidative stress.

Relative hematopoietic stem cell transplantation for the treatment of blastic plasmacytoid dendritic cell neoplasm: a case report and literature review

OBJECTIVE

To report the long-term survival of a patient with maternal plasmacytoid dendritic cell tumor (BPDCN) treated by allo-HSCT.

METHODS

The patient was diagnosed by skin infiltration, bone marrow involvement, skin biopsy and bone marrow cytology. CD4, CD56, and CR123 were expressed in tumor cells. The first complete remission (CR1) was achieved by CHOP-E and MA regimens before transplantation. In March 2018, HLA 5/10 matched hematopoietic stem cell transplantations were performed in the paternal donors and fathers. The pretreatment regimen was FTBI (4 Gy × 2, total lung dose 6 Gy) + CY (cyclophosphamide 1.8 g/m² × 2 d) + Flu (30 mg/m² × 4 d) + ATG (10 mg/kg); CSA + MMF + MTX to prevent GVHD. MNC 6.45 × 10⁸/kg and CD34 + cells 7.40 × 10⁶/kg were transfused back. + Granulocyte and platelet were engrafted 12 days and 14 days respectively. The donor-recipient chimerism was monitored regularly, immunosuppressive agents were regulated, and minimal residual disease (MRD) was monitored by flow cytometry. No DLI.

RESULTS

Complete donor implantation and continuous remission were achieved after transplantation. After transplantation, complications such as mucositis, viral infection, hypoproteinemia, and renal dysfunction occurred. At present, the disease-free survival is 10 months.

CONCLUSION

BPDCN combined with TBI in the CR1 phase can effectively control the disease; HLA haploidentical hematopoietic stem cell transplantation is also an alternative treatment, and complications should be treated in a timely manner.

Evaluating the radioprotective effect of green barley juice on male rats

PURPOSE

DNA damage accounts for most biological effects of ionizing radiation. Antioxidants are known for their protective effect by preventing DNA damage. This pilot study aimed to evaluate the potential radioprotective effect of Natural SOD®, a green barley juice rich in antioxidants, on DNA damage in the testes and lymphocytes of Wistar rats exposed to ionizing radiation.

MATERIALS AND METHODS

Male Wistar rats (n = 15) were selected and equally divided into three groups. Rats in one of the groups were pretreated orally with Natural SOD® for 14 days, while rats in another group were sham-pretreated with saline solution. Rats in both these groups were afterwards subjected to a single dose of 6 Gy X-ray whole-body irradiation. The control group did not receive any treatment and was not irradiated. Shortly after X-ray exposure, all rats were sacrificed and testes and blood were collected. Gamma-H2AX and histopathological assessment in the testes, along with comet assay of lymphocytes were performed.

RESULTS

Histopathological examination of the testes showed no significant architectural alterations. Immunofluorescent staining of γ-H2AX revealed more DNA double-strand break sites in testicular cells from sham animals compared to Natural SOD® pretreated rats. Alkaline comet assay results showed increased DNA damage in lymphocytes of irradiated rats compared to the control group with little differences between the pretreated groups. Animals pretreated with Natural SOD showed slightly reduced DNA damage compared to sham-pretreated rats. These findings suggest a potential protective effect of Natural SOD® against radiation-induced DNA damage.

CONCLUSIONS

Natural SOD® exhibited a potential prophylactic radioprotective effect in rats, particularly in testes. Further investigations to determine medium and long-term effects of X-ray in animals administered Natural SOD® are needed to better estimate the radioprotective effect.

Effective T-cell replete haploidentical stem cell transplantation for pediatric patients with high-risk hematologic disorders

OBJECTIVES

Patients with high-risk hematologic diseases require intensive modalities, including high-dose chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Haploidentical T-cell-replete transplantation is a logical choice because of the limited availability of matched sibling donors and the prolonged time needed to identify matched unrelated donors in Thailand.

METHODS

The clinical outcomes data of 43 patients undergoing allo-HSCT were reviewed. All patients had high-risk hematologic malignancies, were younger than 20 years, and were in complete cytological remission at the time of allo-HSCT. We used two different conditioning regimens: total body irradiation (TBI) combined with cyclophosphamide, fludarabine, and melphalan (n = 23) and thiotepa combined with fludarabine and busulfan (n = 20). All patients received a graft-versus-host disease prophylaxis regimen consisting of cyclophosphamide, mycophenolate mofetil, and a calcineurin inhibitor or sirolimus.

RESULTS

There was no difference in engraftment between patients receiving either of the regimens. After a median follow-up of 35.8 (range, 0.6-106.2) months, the overall survival (OS) and event-free survival (EFS) rates were 62.4% and 54.7%, respectively. OS and EFS were comparable between the respective regimens.

CONCLUSIONS

We conclude that thiotepa-based conditioning has similar efficacy and tolerability as TBI-based conditioning for haploidentical HSCT with post-transplant cyclophosphamide.