Combinations of Cytokines Promote Survival of Mice and Limit Acute Radiation Damage in Concert with Amelioration of Vascular Damage

Protective effects of autologous bone marrow-derived mesenchymal stem cell transplantation on acute radioactive enteritis in Beagle dogs

BACKGROUND

Radiation enteritis is a common complication of radiation therapy in which the surrounding normal intestinal tissue is damaged by ionising radiation, and there is no standard pharmacological prophylaxis or treatment regimen available. Mesenchymal stem cell transplantation can be used for radiation protection and the treatment of acute radiation injury, but its therapeutic mechanism of action remains unclear.

AIM

To investigate the protective effects of autologous bone marrow-derived mesenchymal stem cell (ABMSC) transplantation on radiation-induced intestinal injury.

METHODS

A model of acute radioactive enteritis was established in dogs by applying abdominal intensity-modulated radiation at a single X-ray dose of 12 Gy. ABMSCs were transplanted into the mesenteric artery with the technology of femoral artery puncture and DSA imaging two days after radiation. Visual and histopathological changes of the experimental dogs were observed. Different kinds of cytokines from intestinal samples were tested using Quantibody Canine Cytokine Array method. Enzyme-linked immunosorbent assay (ELISA) was also used to evaluate the cytokines changes in serum.

RESULTS

The ABMSCs group showed significant improvements in survival status compared with the blank and saline treatment groups. Histological observations revealed that the former had lower histological scores than the later after treatment (P < 0.05). Compared to the control groups, interleukin (IL)-10 and monocyte chemotactic protein (MCP)-1 from intestinal samples showed a remarkable increase and ELISA of serum samples proved higher secretion of the two target cytokines in the ABMSCs group (P < 0.05).

CONCLUSION

Our data suggest that transplantation of ABMSCs promotes intestinal recovery after acute radioactive injury in Beagle dogs. The cytokines of IL-10 and MCP-1 might play an important role in this process.

Recombinant human thrombopoietin in alleviating endothelial cell injury in sepsis

BACKGROUND

To evaluate the effect of recombinant human thrombopoietin (rhTPO) on clinical prognosis by exploring changes in endothelial cell injury markers and inflammatory factors in patients with sepsis after treatment with rhTPO.

METHODS

This retrospective observational study involved patients with sepsis (diagnosed according to Sepsis 3.0) admitted to Shanghai General Hospital intensive care unit from January 1, 2019 to December 31, 2022. Patients were divided into two groups (control and rhTPO) according to whether they received rhTPO. Baseline information, clinical data, prognosis, and survival status of the patients, as well as inflammatory factors and immune function indicators were collected. The main monitoring indicators were endothelial cell-specific molecule (ESM-1), human heparin-binding protein (HBP), and CD31; secondary monitoring indicators were interleukin (IL)-6, tumor necrosis factor (TNF)-α, extravascular lung water index, platelet, antithrombin III, fibrinogen, and international normalized ratio. We used intraperitoneal injection of lipopolysaccharide (LPS) to establish a mouse model of sepsis. Mice were randomly divided into four groups: normal saline, LPS, LPS + rhTPO, and LPS + rhTPO + LY294002. Plasma indicators in mice were measured by enzyme-linked immunosorbent assay.

RESULTS

A total of 84 patients were included in the study. After 7 days of treatment, ESM-1 decreased more significantly in the rhTPO group than in the control group compared with day 1 (median=38.6 [interquartile range, IQR: 7.2 to 67.8] pg/mL vs. median=23.0 [IQR: -15.7 to 51.5] pg/mL, P=0.008). HBP and CD31 also decreased significantly in the rhTPO group compared with the control group (median=59.6 [IQR: -1.9 to 91.9] pg/mL vs. median=2.4 [IQR: -23.2 to 43.2] pg/mL; median=2.4 [IQR: 0.4 to 3.5] pg/mL vs. median=-0.6 [IQR: -2.2 to 0.8] pg/mL, P <0.001). Inflammatory markers IL-6 and TNF-α decreased more significantly in the rhTPO group than in the control group compared with day 1 (median=46.0 [IQR: 15.8 to 99.1] pg/mL vs. median=31.2 [IQR: 19.7 to 171.0] pg/mL, P <0.001; median=17.2 [IQR: 6.4 to 23.2] pg/mL vs. median=0.0 [IQR: 0.0 to 13.8] pg/mL, P=0.010). LPS + rhTPO-treated mice showed significantly lower vascular von Willebrand factor (P=0.003), vascular endothelial growth factor (P=0.002), IL-6 (P <0.001), and TNF-α (P <0.001) than mice in the LPS group. Endothelial cell damage factors vascular von Willebrand factor (P=0.012), vascular endothelial growth factor (P=0.001), IL-6 (P <0.001), and TNF-α (P=0.001) were significantly elevated by inhibiting the PI3K/Akt pathway.

CONCLUSION

rhTPO alleviates endothelial injury and inflammatory indices in sepsis, and may regulate septic endothelial cell injury through the PI3K/Akt pathway.

Clinical comprehensive and experimental assessment of the radioprotective effect of Annona muricata leaf extract to prevent cellular damage in the ileum tissue

We report the radioprotective attitude of Annona muricata (AM) leaf extract as antioxidant material to prevent cellular damage in the ileum tissue. The protective effects of an ethyl acetate extract of AM leaves are comprehensively investigated against radiation-induced ileal damage in numerous rats. Thirty-two adult female rats were separated into 4 groups (3 intervention groups and 1 control) as follows: controls received 0.01 mL/kg distilled water, the AM group received 300 mg/kg AM leaf extract, the ionizing radiation (IR) group received a single dose of whole body radiation (8.3 Gy) after 0.01 mL/kg saline treatment, and the AM + IR group received 300 mg/kg AM leaf extract treatment and were subjected to whole body radiation (8.3 Gy) 1 h after the last gavage. All treatments are administered by oral gavage once a day for 9 days. At the end of the experiment, biochemical total oxidant status (TOS, interleukin-6, and caspase) and histological examinations are performed on blood samples as well as ileum tissue. TOS levels are found to be significantly high in rats, which received irradiation, and those in the AM group when compared to controls. These findings suggest that AM has radioprotective effects on ileum tissue, likely because of its antioxidative properties. The findings of this research may contribute to the minimizing of major side effects induced by excessive radiation exposure in patients undergoing radiotherapy and may serve as a significant impetus for further assessments. However, future studies are highly recommended to confirm safety and to determine extraction technique and dosage before human use can be considered.

Hematopoietic Recovery using Multi-Cytokine Therapy in 8 Patients Presenting Radiation-Induced Myelosuppression after Radiological Accidents

Treatment of accidental radiation-induced myelosuppression is primarily based on supportive care and requires specific treatment based on hematopoietic growth factors injection or hematopoietic cell transplantation for the most severe cases. The cytokines used consisted of pegylated erythropoietin (darbepoetin alfa) 500 IU once per week, pegylated G-CSF (pegfilgrastim) 6 mg × 2 once, stem cell factor 20 μg.kg-1 for five days, and romiplostim (TPO analog) 10 μg.kg-1 once per week, with different combinations depending on the accidents. As the stem cell factor did not have regulatory approval for clinical use in France, the French regulatory authorities (ANSM, formerly, AFSSAPS) approved their compassionate use as an investigational drug "on a case-by-case basis". According to the evolution and clinical characteristics, each patient's treatment was adopted on an individual basis. Daily blood count allows initiating G-CSF and SCF delivery when granulocyte <1,000/mm3, TPO delivery when platelets <50,000/mm3, and EPO when Hb<80 g/L. The length of each treatment was based on blood cell recovery criteria. The concept of "stimulation strategy" is linked to each patient's residual hematopoiesis, which varies among them, depending on the radiation exposure's characteristics and heterogeneity. This paper reports the medical management of 8 overexposed patients to ionizing radiation. The recovery of bone marrow function after myelosuppression was accelerated using growth factors, optimized by multiple-line combinations. Particularly in the event of prolonged exposure to ionizing radiation in dose ranges inducing severe myelosuppression (in the order of 5 to 8 Gy), with no indication of hematopoietic stem cell transplantation.

IL-11 mediates the Radioresistance of Cervical Cancer Cells via the PI3K/Akt Signaling Pathway

Cervical cancer is one of the most common malignant tumors in the female reproductive system. Radioresistance remains a significant factor that limits the efficacy of radiotherapy for cervical cancer. Interleukin-11 (IL-11) has been reported to be upregulated in various types of human cancer and correlate with clinical stage and poor survival. However, the exact effects and mechanisms of IL-11 in the radioresistance of cervical cancer have not yet been defined. In this research, TCGA databases revealed that IL-11 expression was upregulated in cervical cancer tissues and was associated with clinical stages and poor prognosis in cervical cancer patients. We discovered that IL-11 concentration was significantly upregulated in radioresistant cervical cancer cells. Knocking down IL-11 in Hela cells could reduce clonogenic survival rate, decrease cell viability, induce G2/M phase block, and facilitate cell apoptosis. In contrast, Exogeneous IL-11 in C33A cells could upregulate clonogenic survival rate, increase cell viability, curb G2/M phase block, and cell apoptosis. Mechanistic investigations showed that radioresistance conferred by IL-11 was attributed to the activation of the PI3K/Akt signaling pathway. Altogether, our results demonstrate that IL-11 might be involved in radioresistance, and IL-11 may be a potent radiosensitization target for cervical cancer therapy.

Mechanism of Action of Diallyl Sulphide in Ameliorating the Hematopoietic Radiation Injury

Diallyl sulphide (DAS), the pungent component of garlic, is known to have several medicinal properties and has recently been shown to have radiomitigative properties. The present study was performed to better understand its mode of action in rendering radiomitigation. Evaluation of the colonogenic ability of hematopoietic progenitor cells (HPCs) on methocult media, proliferation and differentiation of hematopoietic stem cells (HSCs), and transplantation of stem cells were performed. The supporting tissue of HSCs was also evaluated by examining the histology of bone marrow and in vitro colony-forming unit–fibroblast (CFU-F) count. Alterations in the levels of IL-5, IL-6 and COX-2 were studied as a function of radiation or DAS treatment. It was observed that an increase in proliferation and differentiation of hematopoietic stem and progenitor cells occurred by postirradiation DAS administration. It also resulted in increased circulating and bone marrow homing of transplanted stem cells. Enhancement in bone marrow cellularity, CFU-F count, and cytokine IL-5 level were also evident. All those actions of DAS that could possibly add to its radiomitigative potential and can be attributed to its HDAC inhibitory properties, as was observed by the reversal radiation induced increase in histone acetylation.

Homing of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) Labeled Adipose-Derived Stem Cells by Magnetic Attraction in a Rat Model of Parkinson's Disease

Introduction

Stem cell therapies for neurodegenerative diseases such as Parkinson’s disease (PD) are intended to replace lost dopaminergic neurons. The basis of this treatment is to guide the migration of transplanted cells into the target tissue or injury site. The aim of this study is an evaluation of the homing of superparamagnetic iron oxide nanoparticles (SPIONs) labeled adipose-derived stem cells (ADSC) by an external magnetic field in a rat model of PD.

Methods

ADSCs were obtained from perinephric regions of male adult rats and cultured in a DMEM medium. ADSC markers were assessed by immunostaining with CD90, CD105, CD49d, and CD45. The SPION was coated using poly-L-lysine hydrobromide and transfection was determined in rat ADSC using the GFP reporter gene. For this in vivo study, rats with PD were divided into five groups: a positive control group, a control group with PD (lesion with 6-HD injection), and three treatment groups: the PD/ADSC group (PD transplant with ADSCs transfected by BrdU), PD/ADSC/SPION group (PD transplant with ADSCs labeled with SPION and transfected by GFP), and the PD/ADSC/SPION/EM group (PD transplant with ADSCs labeled with SPION and transfected by GFP induced with external magnet).

Results

ADSCs were immunoreactive to fat markers CD90 (90.73±1.7), CD105 (87.4±2.9) and CD49d (79.6±2.6), with negative immunostaining at the hematopoietic stem cell marker (CD45: 1.4±0.4). The efficiency of cells with SPION/PLL was about 96% of ADSC. The highest number of GFP-positive cells was in the ADSC/SPION/EM group (54.5±1.3), which was significantly different from that in ADSC/SPION group (30.83±3 and P<0.01).

Conclusion

Transfection of ADSC by SPION/PLL is an appropriate protocol for cell therapy. External magnets can be used for the delivery and homing of transplanted stem cells in the target tissue.

Radioprotective Activity of Naturally Occurring Organosulfur Compounds

The radioprotective effects of naturally occurring sulfur compounds and isothiocyanates such as diallyl sulfide (DAS), diallyl disulfide (DADS), allyl methyl sulfide (AMS), allyl isothiocyanate (AITC) and phenyl isothiocyanate (PITC) have been investigated in whole body irradiated Swiss albino mice. Administration of these sulfur compounds could reduce the serum content of alkaline phosphatase (ALP), which was elevated after irradiation (23.9 ± 1.82 KA units). The elevated liver content of glutamate pyruvate transaminase (GPT) in control animals (76.2 ± 2.2 U/mL) after irradiation was significantly reduced in DAS (58.93 ± 4 U/mL) and AMS (55.7 ± 2.2 U/mL) treated animals. Elevated levels of lipid peroxides in serum and liver of irradiated control animals were also significantly reduced by treatment with these sulfur compounds. The glutathione (GSH) content in liver and intestinal mucosa was drastically reduced after irradiation. All the sulfur compounds and isothiocyanates could effectively enhance the GSH content of intestinal mucosa and liver. Findings at histopathological analysis of the intestine proved to be correlated with the above results.

Early and Late Protective Effect of Bone Marrow Mononuclear Cell Transplantation on Radiation-Induced Vascular Dysfunction and Skin Lesions

Skin lesions caused by accidental exposure to radiation or by radiotherapy are a major clinical challenge. We evaluated the effect of bone marrow mononuclear cells (BMMNC) on collagen remodeling and vascular function in radiation-induced skin lesions in the acute and late phases in mice. We studied the effect of BMMNC transplantation in a mouse model of cutaneous radiation injury combining local skin gamma-irradiation and biopsy punch wound. Mice were first irradiated, punched and then BMMNC were intramuscularly administered. Seven days after injury, BMMNC promoted wound healing by (i) increasing re-epithelialization, tissue collagen density and mRNA levels of collagens 1A1, 1A2, and 3A1, and (ii) inhibiting the radiation-induced vascular activation and limiting interactions between leukocytes and the vascular endothelium compared with control. Importantly, BMMNC did not amplify the inflammatory response despite the infiltration of neutrophils and macrophages associated with the expression of IL-6 and MCP-1 mRNAs in the tissue. Remarkably, the beneficial effects of BMMNC therapy on matrix remodeling were maintained for 2 months. Furthermore, BMMNC injection restored vascular function in skin tissue by increasing vascular density and vascular permeability. This therapeutic strategy based on BMMNC injection protects against radiation-induced skin lesions by preventing vascular dysfunction and unfavorable remodeling in the acute and late phases.

rBPI21 (Opebacan) Promotes Rapid Trilineage Hematopoietic Recovery in a Murine Model of High-Dose Total Body Irradiation

The complexity of providing adequate care after radiation exposure has drawn increasing attention. While most therapeutic development has focused on improving survival at lethal radiation doses, acute hematopoietic syndrome (AHS) occurs at substantially lower exposures. Thus, it is likely that a large proportion of such a radiation-exposed population will manifest AHS of variable degree and that the medical and socioeconomic costs of AHS will accrue. Here, we examined the potential of rBPI21 (opebacan), used without supportive care, to accelerate hematopoietic recovery after radiation where expected survival was substantial (42-75%) at 30 days). rBPI21 administration was associated with accelerated recovery of hematopoietic precursors and normal marrow cellularity, with increases in megakaryocyte numbers particularly marked. This translated into attaining normal trilineage peripheral blood counts 2-3 weeks earlier than controls. Elevations of hematopoietic growth factors observed in plasma and the marrow microenvironment suggest the mechanism is likely multifactorial and not confined to known endotoxin-neutralizing and cytokine down-modulating activities of rBPI21 . These observations deserve further exploration in radiation models and other settings where inadequate hematopoiesis is a prominent feature. These experiments also model the potential of therapeutics to limit the allocation of scarce resources after catastrophic exposures as an endpoint independent of lethality mitigation. This article is protected by copyright. All rights reserved.

Further Characterization of the Mitigation of Radiation Lethality by Protective Wounding

There continues to be a major effort in the United States to develop mitigators for the treatment of mass casualties that received high-intensity acute ionizing radiation exposures from the detonation of an improvised nuclear device during a radiological terrorist attack. The ideal countermeasure should be effective when administered after exposure, and over a wide range of absorbed doses. We have previously shown that the administration of a subcutaneous incision of a defined length, if administered within minutes after irradiation, protected young adult female C57BL/6 mice against radiation-induced lethality, and increased survival after total-body exposure to an LD_50/30 X-ray dose from 50% to over 90%. We refer to this approach as "protective wounding". In this article, we report on our efforts to further optimize, characterize and demonstrate the validity of the protective wounding response by comparing the response of female and male mice, varying the radiation dose, the size of the wound, and the timing of wounding with respect to administration of the radiation dose. Both male and female mice that received a subcutaneous incision after irradiation were significantly protected from radiation lethality. We observed that the extent of protection against lethality after an LD_50/30 X-ray dose was independent of the size of the subcutaneous cut, and that a 3 mm subcutaneous incision is effective at enhancing the survival of mice exposed to a broad range of radiation doses (LD₁₅-LD₁₀₀). Over the range of 6.2-6.7 Gy, the increase in survival observed in mice that received an incision was associated with an enhanced recovery of hematopoiesis. The enhanced rate of recovery of hematopoiesis was preceded by an increase in the production of a select group of cytokines. Thus, a thorough knowledge of the timing of the cytokine cascade after wounding could aid in the development of novel pharmacological radiation countermeasures that can be administered several days after the actual radiation exposure.

Pathology and biology of radiation-induced cardiac disease

Heart disease is the leading global cause of death. The risk for this disease is significantly increased in populations exposed to ionizing radiation, but the mechanisms are not fully elucidated yet. This review aims to gather and discuss the latest data about pathological and biological consequences in the radiation-exposed heart in a comprehensive manner. A better understanding of the molecular and cellular mechanisms underlying radiation-induced damage in heart tissue and cardiac vasculature will provide novel targets for therapeutic interventions. These may be valuable for individuals clinically or occupationally exposed to varying doses of ionizing radiation.

A study of the effect of sequential injection of 5-androstenediol on irradiation-induced myelosuppression in mice

Herein, we aimed at examining the therapeutic effects of 5-androstenediol (5-AED), a natural hormone produced in the adrenal cortex, on radiation-induced myelosuppression in C3H/HeN mice. The mice were subjected to whole-body irradiation with a sublethal dose of 5 Gy gamma-irradiation to induce severe myelosuppression, and 5-AED (50 mg/kg) was administered subcutaneously. 5-AED was administrated 1 day before irradiation (pre-treatment) or twice weekly for 3 weeks starting from 1 h after irradiation (post-treatment). Treatment with 5-AED significantly ameliorated the decrease in the peripheral blood neutrophil and platelet populations in irradiated myelosuppressive mice, but had no effect on the lymphocyte population. It also ameliorated hypocellularity and disruption of bone marrow induced by irradiation and led to rapid recovery of myeloid cells. Further, it attenuated the decrease in spleen weight and megakaryocyte and myeloid cell populations in the spleen and promoted multilineage hematopoietic recovery. We found that a single injection of 5-AED produced only a temporary therapeutic effect, while sequential injection of 5-AED after irradiation had a more pronounced and prolonged therapeutic effect and reduced myelosuppression by irradiation. Thus, sequential injection of 5-AED after irradiation has therapeutic potential for radiation-induced myelosuppression when administered continuously and can be a significant therapeutic candidate for the management of acute radiation syndrome, particularly in a mass casualty scenario where rapid and economic intervention is important.

Subcutaneous wounding postirradiation reduces radiation lethality in mice

The detonation of an improvised nuclear device during a radiological terrorist attack could result in the exposure of thousands of civilians and first responders to lethal or potentially lethal doses of ionizing radiation (IR). There is a major effort in the United States to develop phamacological mitigators of radiation lethality that would be effective particularly if administered after irradiation. We show here that giving female C57BL/6 mice a subcutaneous surgical incision after whole body exposure to an LD50/30 X-ray dose protects against radiation lethality and increases survival from 50% to over 90% (P = 0.0001). The increase in survival, at least in part, appears to be due to enhanced recovery of hematopoiesis, notably red blood cells, neutrophils and platelets. While a definitive mechanism has yet to be elucidated, we propose that this approach may be used to identify potentially novel mechanisms and pathways that could aid in the development of novel pharmacological radiation countermeasures.

PEGylated G-CSF (BBT-015), GM-CSF (BBT-007), and IL-11 (BBT-059) analogs enhance survival and hematopoietic cell recovery in a mouse model of the hematopoietic syndrome of the acute radiation syndrome

Hematopoietic growth factors (HGF) are recommended therapy for high dose radiation exposure, but unfavorable administration schedules requiring early and repeat dosing limit the logistical ease with which they can be used. In this report, using a previously described murine model of H-ARS, survival efficacy and effect on hematopoietic recovery of unique PEGylated HGF were investigated. The PEGylated-HGFs possess longer half-lives and more potent hematopoietic properties than corresponding non-PEGylated-HGFs. C57BL/6 mice underwent single dose lethal irradiation (7.76-8.72 Gy, Cs, 0.62-1.02 Gy min) and were treated with various dosing regimens of 0.1, 0.3, and 1.0 mg kg of analogs of human PEG-G-CSF, murine PEG-GM-CSF, or human PEG-IL-11. Mice were administered one of the HGF analogs at 24-28 h post irradiation, and in some studies, additional doses given every other day (beginning with the 24-28 h dose) for a total of three or nine doses. Thirty-day (30 d) survival was significantly increased with only one dose of 0.3 mg kg of PEG-G-CSF and PEG-IL-11 or three doses of 0.3 mg kg of PEG-GM-CSF (p ≤ 0.006). Enhanced survival correlated with consistently and significantly enhanced WBC, NE, RBC, and PLT recovery for PEG-G- and PEG-GM-CSF, and enhanced RBC and PLT recovery for PEG-IL-11 (p ≤ 0.05). Longer administration schedules or higher doses did not provide a significant additional survival benefit over the shorter, lower dose, schedules. These data demonstrate the efficacy of BBT's PEG-HGF to provide significantly increased survival with fewer injections and lower drug doses, which may have significant economic and logistical value in the aftermath of a radiation event.

Bactericidal/permeability-increasing protein (rBPI21) and fluoroquinolone mitigate radiation-induced bone marrow aplasia and death

Identification of safe, effective treatments to mitigate toxicity after extensive radiation exposure has proven challenging. Only a limited number of candidate approaches have emerged, and the U.S. Food and Drug Administration has yet to approve any agent for a mass-casualty radiation disaster. Because patients undergoing hematopoietic stem cell transplantation undergo radiation treatment that produces toxicities similar to radiation-disaster exposure, we studied patients early after such treatment to identify new approaches to this problem. Patients rapidly developed endotoxemia and reduced plasma bactericidal/permeability-increasing protein (BPI), a potent endotoxin-neutralizing protein, in association with neutropenia. We hypothesized that a treatment supplying similar endotoxin-neutralizing activity might replace the BPI deficit and mitigate radiation toxicity and tested this idea in mice. A single 7-Gy radiation dose, which killed 95% of the mice by 30 days, was followed 24 hours later by twice-daily, subcutaneous injections of the recombinant BPI fragment rBPI21 or vehicle alone for 14 or 30 days, with or without an oral fluoroquinolone antibiotic with broad-spectrum antibacterial activity, including that against endotoxin-bearing Gram-negative bacteria. Compared to either fluoroquinolone alone or vehicle plus fluoroquinolone, the combined rBPI21 plus fluoroquinolone treatment improved survival, accelerated hematopoietic recovery, and promoted expansion of stem and progenitor cells. The observed efficacy of rBPI21 plus fluoroquinolone initiated 24 hours after lethal irradiation, combined with their established favorable bioactivity and safety profiles in critically ill humans, suggests the potential clinical use of this radiation mitigation strategy and supports its further evaluation.

After the bomb drops: a new look at radiation-induced multiple organ dysfunction syndrome (MODS)

PURPOSE

There is increasing concern that, since the Cold War era, there has been little progress regarding the availability of medical countermeasures in the event of either a radiological or nuclear incident. Fortunately, since much is known about the acute consequences that are likely to be experienced by an exposed population, the probability of survival from the immediate hematological crises after total body irradiation (TBI) has improved in recent years. Therefore focus has begun to shift towards later down-stream effects, seen in such organs as the gastrointestinal tract (GI), skin, and lung. However, the mechanisms underlying therapy-related normal tissue late effects, resulting from localised irradiation, have remained somewhat elusive and even less is known about the development of the delayed syndrome seen in the context of whole body exposures, when it is likely that systemic perturbations may alter tissue microenvironments and homeostasis.

CONCLUSIONS

The sequence of organ failures observed after near-lethal TBI doses are similar in many ways to that of multiple organ dysfunction syndrome (MODS), leading to multiple organ failure (MOF). In this review, we compare the mechanistic pathways that underlie both MODS and delayed normal tissue effects since these may impact on strategies to identify radiation countermeasures.

Medical countermeasures for platelet regeneration after radiation exposure. Report of a workshop and guided discussion sponsored by the National Institute of Allergy and Infectious Diseases, Bethesda, MD, March 22–23, 2010

The events of September 11, 2001 and their aftermath increased awareness of the need to develop medical countermeasures (MCMs) to treat potential health consequences of a radiation accident or deliberate attack. The medical effects of lethal exposures to ionizing radiation have been well described and affect multiple organ systems. To date, much of the research to develop treatments for mitigation of radiation-induced hematopoietic damage has focused on amelioration of radiation-induced neutropenia, which has long been considered to be the primary factor in determining survival after an unintentional radiation exposure. Consistent with historical data, recent studies have highlighted the role that radiation-induced thrombocytopenia plays in radiation mortality, yet development of MCMs to mitigate radiation damage to the megakaryocyte lineage has lagged behind anti-neutropenia approaches. To address this gap and to foster research in the area of platelet regeneration after radiation exposure, the National Institute of Allergy and Infectious Diseases (NIAID) sponsored a workshop on March 22-23, 2010 to encourage collaborations between NIAID program awardees and companies developing pro-platelet approaches. NIAID also organized an informal, open discussion between academic investigators, product development contractors, and representatives from the U.S. Food and Drug Administration (FDA) and other relevant government agencies about drug development toward FDA licensure of products for an acute radiation syndrome indication. Specific emphasis was placed on the challenges of product licensure for radiation/nuclear MCMs using current FDA regulations (21 CFR Parts 314 and 601) and on the importance of animal efficacy model development, design of pivotal protocols, and standardization of irradiation and animal supportive care.

Local irradiation not only induces homing of human mesenchymal stem cells at exposed sites but promotes their widespread engraftment to multiple organs: a study of their quantitative distribution after irradiation damage

Mesenchymal stem cells (MSCs) have been shown to migrate to various tissues. There is little information on the fate and potential therapeutic efficacy of the reinfusion of MSCs following total body irradiation (TBI). We addressed this question using human MSC (hMSCs) infused to nonobese diabetic/ severe combined immunodeficient (NOD/SCID) mice submitted to TBI. Further, we tested the impact of additional local irradiation (ALI) superimposed to TBI, as a model of accidental irradiation. NOD/SCID mice were transplanted with hM-SCs. Group 1 was not irradiated before receiving hMSC infusion. Group 2 received only TBI at a dose of 3.5 Gy, group 3 received local irradiation to the abdomen at a dose of 4.5 Gy in addition to TBI, and group 4 received local irradiation to the leg at 26.5 Gy in addition to TBI. Fifteen days after irradiation, quantitative and spatial distribution of the hMSCs were studied. Histological analysis of mouse tissues confirmed the presence of radio-induced lesions in the irradiated fields. Following their infusion into nonirradiated animals, hMSCs homed at a very low level to various tissues (lung, bone marrow, and muscles) and no significant engraftment was found in other organs. TBI induced an increase of engraftment levels of hMSCs in the brain, heart, bone marrow, and muscles. Abdominal irradiation (AI) as compared with leg irradiation (LI) increased hMSC engraftment in the exposed area (the gut, liver, and spleen). Hind LI as compared with AI increased hMSC engraftment in the exposed area (skin, quadriceps, and muscles). An increase of hMSC engraftment in organs outside the fields of the ALI was also observed. Conversely, following LI, hMSC engraftment was increased in the brain as compared with AI. This study shows that engraftment of hMSCs in NOD/ SCID mice with significantly increased in response to tissue injuries following TBI with or without ALI. ALI induced an increase of the level of engraftment at sites outside the local irradiation field, thus suggesting a distant (abscopal) effect of radiation damage. This work supports the use of MSCs to repair damaged normal tissues following accidental irradiation and possibly in patients submitted to radiotherapy.

Endogenous IL-11 signaling is essential in Th2- and IL-13-induced inflammation and mucus production

IL-11 and IL-11 receptor (R)alpha are induced by Th2 cytokines. However, the role(s) of endogenous IL-11 in antigen-induced Th2 inflammation has not been fully defined. We hypothesized that IL-11, signaling via IL-11Ralpha, plays an important role in aeroallergen-induced Th2 inflammation and mucus metaplasia. To test this hypothesis, we compared the responses induced by the aeroallergen ovalbumin (OVA) in wild-type (WT) and IL-11Ralpha-null mutant mice. We also generated and defined the effects of an antagonistic IL-11 mutein on pulmonary Th2 responses. Increased levels of IgE, eosinophilic tissue and bronchoalveolar lavage (BAL) inflammation, IL-13 production, and increased mucus production and secretion were noted in OVA-sensitized and -challenged WT mice. These responses were at least partially IL-11 dependent because each was decreased in mice with null mutations of IL-11Ralpha. Importantly, the administration of the IL-11 mutein to OVA-sensitized mice before aerosol antigen challenge also caused a significant decrease in OVA-induced inflammation, mucus responses, and IL-13 production. Intraperitoneal administration of the mutein to lung-specific IL-13-overexpressing transgenic mice also reduced BAL inflammation and airway mucus elaboration. These studies demonstrate that endogenous IL-11R signaling plays an important role in antigen-induced sensitization, eosinophilic inflammation, and airway mucus production. They also demonstrate that Th2 and IL-13 responses can be regulated by interventions that manipulate IL-11 signaling in the murine lung.

Mesenchymal stem cells increase self-renewal of small intestinal epithelium and accelerate structural recovery after radiation injury

Patients who undergo pelvic or abdominal radiotherapy may develop side effects that can be life threatening. Tissue complications caused by radiation-induced stem cell depletion may result in structural and functional alterations of the gastrointestinal (GI) tract. Stem cell therapy using mesenchymal stem cells (MSC) is a promising approach for replenishment of the depleted stem cell compartment during radiotherapy. There is little information on the therapeutic potential of MSC in injured-GI tract following radiation exposure. In this study, we addressed the ability of MSC to support the structural regeneration of the small intestine after abdominal irradiation. We isolated MSC from human bone marrow and human mesenchymal stem cells (hMSC) were transplanted into immunotolerent NOD/SCID mice with a dose of 5.10(6) cells via the systemic route. Using a model of radiation-induced intestinal injury, we studied the link between damage, hMSC engraftment and the capacity of hMSC to sustain structural recovery. Tissue injury was assessed by histological analysis. hMSC engraftment in tissues was quantified by PCR assay. Following abdominal irradiation, the histological analysis of small intestinal structure confirms the presence of partial and transient (three days) mucosal atrophy. PCR analysis evidences a low but significant hMSC implantation in small intestine (0.17%) but also at all the sites of local irradiation (kidney, stomach and spleen). Finally, in presence of hMSC, the small intestinal structure is already recovered at three days after abdominal radiation exposure. We show a structural recovery accompanied by an increase of small intestinal villus height, three and fifteen days following abdominal radiation exposure. In this study, we show that radiation-induced small intestinal injury may play a role in the recruitment of MSC for the improvement of tissue recovery. This work supports, the use of MSC infusion to repair damaged GI tract in patients subjected to radiotherapy. MSC therapy to avoid extended intestinal crypt sterilization is a promising approach to diminish healthy tissue alterations during the course of pelvic radiotherapy.

The protective effect of interleukin-11 on the cell death induced by X-ray irradiation in cultured intestinal epithelial cell

Interleukin-11 (IL-11) is a well known anti-inflammatory cytokine that is associated with cell growth, and also participates in limiting X-ray irradiation induced intestinal mucosal injury. The aim of this study was to evaluate the protective effect of IL-11 on the cell injury induced by X-ray irradiation in rat intestinal epithelial IEC-18 cells. Recombinant human IL-11 (rhIL-11) treated cells were irradiated and then examined for cell viability. To evaluate irradiation injury, trypan blue staining was used to detect the dead cells. The viability of irradiated cells was up-regulated by rhIL-11 treatment and also resulted in the activation of p90 ribosomal S6 kinase (p90RSK) and S6 ribosomal protein (S6Rp). Wortmannin, a specific inhibitor of PI3K, suppressed the activation of S6Rp in rhIL-11 treated cells, and decreased the up-regulation of viability by rhIL-11 treatment in irradiated cells. The TUNEL assay was also perfomed to estimate the rate of apoptosis in X-ray induced cell death. There was no difference in the results between trypan blue staining and the TUNEL assay. Further, rhIL-11 down-regulated the expression of cleaved caspase-3 in irradiated cells. These results suggest that rhIL-11 may play an important role in protection from radiation injury.

Effects of whole-body gamma irradiation and 5-androstenediol administration on serum G-CSF

5-Androstenediol (5-AED) is a natural circulating adrenocortical steroid hormone that interconverts in vivo with other members of the 5-androstene family of steroids: dehydroepiandrosterone and 5-androstenetriol. These steroids stimulate immune responses and resistance to infection. 5-AED has been identified as a systemic radiation countermeasure that enhances survival in mice exposed to gamma irradiation and ameliorates radiation-induced neutropenia in mice and nonhuman primates. 5-AED mitigates radiation-induced decreases in platelets, natural killer (NK) cells, red blood cells, and monocytes. Administration of 5-AED causes functional activation of circulating granulocytes (phagocytic ability), monocytes (oxidative burst), and NK cells (surface CD11b expression). The effects of 5-AED on survival and hematological parameters are consistent with induction of hematopoietic cytokines. To test this hypothesis, we measured serum cytokines by ELISA, Luminex, and a cytokine array. A cytokine array was used for 62 different cytokines, chemokines, growth factors, and soluble receptors. 5-AED caused significant increases in circulating granulocyte colony-stimulating factor (G-CSF) in irradiated and unirradiated animals as observed with ELISA and Luminex. The cytokine array results suggest induction of G-CSF and additional cytokines, and related molecules. Since G-CSF is an important hematopoietic cytokine, the results support our hypothesis that the previously observed increases in numbers of hematopoietic progenitors, circulating innate immune cells and platelets, and functional activation of granulocytes, monocytes, and NK cells result from a cytokine cascade induced by 5-AED.

Cytokine-based treatment of accidentally irradiated victims and new approaches

A major goal of medical management of acute radiation syndrome following accidental exposures to ionizing radiation (IR) is to mitigate the risks of infection and hemorrhage related to the period of bone marrow aplasia. This can be achieved by stimulating the proliferation and differentiation of residual hematopoietic stem and progenitor cells (HSPC) related to either their intrinsic radioresistance or the heterogeneity of dose distribution. This is the rationale for treatment with hematopoietic growth factors. In fact, apoptosis has recently been shown to play a major role in the death of the continuum of more or less radiosensitive HSPC, soon after irradiation. Therefore, administration of antiapoptotic cytokine combinations such as stem cell factor, Flt-3 ligand, thrombopoietin, and interleukin-3 (4F), may be important for multilineage recovery, particularly when these factors are administered early. Moreover, acute exposure to high doses of IR induces sequential, deleterious effects responsible for a delayed multiple organ dysfunction syndrome. These considerations strongly suggest that therapeutics could include tissue-specific cytokines, such as keratinocyte growth factor, and pleiotropic agents, such as erythropoietin, in addition to hematopoietic growth factors to ensure tissue damage repair and mitigate the inflammatory processes. Noncytokine drugs have also been proposed as an alternative to treat hematopoietic or nonhematopoietic radiation effects. To develop more effective treatments for radiation injuries, basic research is required, particularly to improve understanding of stem cell needs within their environment. In the context of radiological terrorism and radiation accidents, new growth promoting molecules need to be approved and available cytokines stockpiled.

Mesenchymal stem cells support expansion of in vitro irradiated CD34(+) cells in the presence of SCF, FLT3 ligand, TPO and IL3: potential application to autologous cell therapy in accidentally irradiated victims

Ex vivo expansion of residual autologous hematopoietic stem and progenitor cells collected from victims soon after accidental irradiation (autologous cell therapy) may represent an additional or alternative approach to cytokine therapy or allogeneic transplantation. Peripheral blood CD34+ cells could be a useful source of cells for this process provided that collection and ex vivo expansion of hematopoietic stem and progenitor cells could be optimized. Here we investigated whether mesenchymal stem cells could sustain culture of irradiated peripheral blood CD34+ cells. In vitro irradiated (4 Gy 60Co gamma rays) or nonirradiated mobilized peripheral blood CD34+ cells from baboons were cultured for 7 days in a serum-free medium supplemented with stem cell factor+thrombopoietin+interleukin 3+FLT3 ligand (50 ng/ml each) in the presence or absence of mesenchymal stem cells. In contrast to cultures without mesenchymal stem cells, irradiated CD34+ cells cultured with mesenchymal stem cells displayed cell amplification, i.e. CD34+ (4.9-fold), CD34++ (3.8-fold), CD34++/Thy-1+ (8.1-fold), CD41+ (12.4-fold) and MPO+ (50.6-fold), although at lower levels than in nonirradiated CD34+ cells. Fourteen times more clonogenic cells, especially BFU-E, were preserved when irradiated cells were cultured on mesenchymal stem cells. Moreover, we showed that the effect of mesenchymal stem cells is related mainly to the reduction of apoptosis and involves cell-cell contact rather than production of soluble factor(s). This experimental model suggests that mesenchymal stem cells could provide a crucial tool for autologous cell therapy applied to accidentally irradiated victims.

IL-11 receptor alpha in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 is a major stimulator of inflammation and tissue remodeling at sites of Th2 inflammation. In Th2-dominant inflammatory disorders such as asthma, IL-11 is simultaneously induced. However, the relationship(s) between IL-11 and IL-13 in these responses has not been defined, and the role(s) of IL-11 in the genesis of the tissue effects of IL-13 has not been evaluated. We hypothesized that IL-11, signaling via the IL-11Ralpha-gp130 receptor complex, plays a key role in IL-13-induced tissue responses. To test this hypothesis we compared the expression of IL-11, IL-11Ralpha, and gp130 in lungs from wild-type mice and transgenic mice in which IL-13 was overexpressed in a lung-specific fashion. We simultaneously characterized the effects of a null mutation of IL-11Ralpha on the tissue effects of transgenic IL-13. These studies demonstrate that IL-13 is a potent stimulator of IL-11 and IL-11Ralpha. They also demonstrate that IL-13 is a potent stimulator of inflammation, fibrosis, hyaluronic acid accumulation, myofibroblast accumulation, alveolar remodeling, mucus metaplasia, and respiratory failure and death in mice with wild-type IL-11Ralpha loci and that these alterations are ameliorated in the absence of IL-11Ralpha. Lastly, they provide insight into the mechanisms of these processes by demonstrating that IL-13 stimulates CC chemokines, matrix metalloproteinases, mucin genes, and gob-5 and stimulates and activates TGF-beta1 via IL-11Ralpha-dependent pathways. When viewed in combination, these studies demonstrate that IL-11Ralpha plays a key role in the pathogenesis of IL-13-induced inflammation and remodeling.