ACUTE RADIATION SICKNESS IN HUMAN: ETIOPATHOGENESIS, CLINIC, DIAGNOSIS AND TREATMENT (LECTURE)

Under the conditions of war in Ukraine, there remains a high probability that russia will use nuclear weapons or commit terrorist acts against nuclear power plants, which will lead to exposure of the population in doses that cause acute radiation sickness (ARS). In this regard, our medical service must be ready for the treatment of ARS of various degrees of severity under a mass influx of victims. In peacetime, ARS is a rather infrequent pathology, so most doctors lack experience in its treatment. This article, having the form of a lecture, presents material on the pathogenesis, classification, clinic, diagnosis and treatment of ARS, taking into account the modern achievements of radiation medicine. Treatment of ARS is based on the use of pharmaceutical drugs that are licensed in Ukraine. The article will be useful for doctors and medical workers of all branches and levels of health care, who will have to deal with irradiated persons in order to timely identify patients with ARS and provide them with effective treatment.

Polypharmacy to Mitigate Acute and Delayed Radiation Syndromes

There is a need for countermeasures to mitigate lethal acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE). In WAG/RijCmcr rats, ARS occurs by 30-days following total body irradiation (TBI), and manifests as potentially lethal gastrointestinal (GI) and hematopoietic (H-ARS) toxicities after >12.5 and >7 Gy, respectively. DEARE, which includes potentially lethal lung and kidney injuries, is observed after partial body irradiation >12.5 Gy, with one hind limb shielded (leg-out PBI). The goal of this study is to enhance survival from ARS and DEARE by polypharmacy, since no monotherapy has demonstrated efficacy to mitigate both sets of injuries. For mitigation of ARS following 7.5 Gy TBI, a combination of three hematopoietic growth factors (polyethylene glycol (PEG) human granulocyte colony-stimulating factor (hG-CSF), PEG murine granulocyte-macrophage-CSF (mGM-CSF), and PEG human Interleukin (hIL)-11), which have shown survival efficacy in murine models of H-ARS were tested. This triple combination (TC) enhanced survival by 30-days from ∼25% to >60%. The TC was then combined with proven medical countermeasures for GI-ARS and DEARE, namely enrofloxacin, saline and the angiotensin converting enzyme inhibitor, lisinopril. This combination of ARS and DEARE mitigators improved survival from GI-ARS, H-ARS, and DEARE after 7.5 Gy TBI or 13 Gy PBI. Circulating blood cell recovery as well as lung and kidney function were also improved by TC + lisinopril. Taken together these results demonstrate an efficacious polypharmacy to mitigate radiation-induced ARS and DEARE in rats.

Severe Neutropenia and Agranulocytosis Related to Antithyroid Drugs: A Study of 30 Cases Managed in A Single Reference Center

BACKGROUND

The most important series devoted to antithyroid drug-induced severe neutropenia and agranulocytosis are Japanese studies, almost specifically in relation to the intake of methimazole. The clinical data of 30 Caucasian patients followed up for antithyroid drug-induced neutropenia at a third-level hospital are reported. Methods: The data of 30 patients with idiosyncratic antithyroid drug-induced neutropenia and agranulocytosis from a cohort study on drug-induced neutropenia and agranulocytosis conducted at the University Hospital of Strasbourg (France) were retrospectively reviewed. Results: The mean patient age was 61.7 years old (range: 20-87), and the gender ratio (F/M) was 4. Several comorbidities were reported in 23 patients (76.7%), with the mean Charlson comorbidity index of 1. The causative drugs were carbimazole and benzylthiouracil, in 28 (93.3%) and 2 cases, respectively, prescribed primarily for multi-hetero-nodular goiter or thyroid nodule to 18 patients (60%). Sore throat and acute tonsillitis (40%), isolated fever (20%), septicemia (13.3%), documented pneumonia (6.7%), and septic shock (6.7%) were the main clinical features upon admission. The mean neutrophil count at nadir was 0.02 and 0 × 109/L (range: 0-0.3). Regarding the patients' hospital course: 13 cases (43.3%) worsened during hospitalization, severe sepsis was found in 26.7%, systemic inflammatory response syndrome-in 13.3%, and septic shock-in 3.3% of the cases, respectively. Broad-spectrum antibiotics were indicated for all the patients, and 21 (73.3%) of them received hematopoietic growth factors. Hematological recovery (neutrophil count ≥ 1.5 × 109/L) was seen at 8.3 days (range: 2-24), but faster in those receiving hematopoietic growth factors (4.9 days, p = 0.046). Two patients died during hospitalization, and the rest had a favorable clinical outcome. Conclusions: Antithyroid drug-induced neutropenia represents a serious complication resulting from the rates of severe infections especially in those cases severe neutropenia. In this setting, an established procedure for the management of patients seems useful or even indispensable in view of potential mortality.

CCR5 Signaling Promotes Murine and Human Hematopoietic Regeneration following Ionizing Radiation

Hematopoietic stem and progenitor cells (HSPCs) depend on regulatory cytokines from the marrow microenvironment. From an unbiased cytokine screen of murine marrow supernatants, we identified C-C motif chemokine ligand 5 (CCL5) as an endothelial cell-secreted hematopoietic growth factor. Following treatment with CCL5, hematopoietic regeneration is accelerated and survival is prolonged after radiation. In mice with deletion of Ccr5, hematopoietic regeneration is delayed compared to control mice. Deletion of Ccr5 specifically in hematopoietic cells was sufficient to delay regeneration, while the deletion of Ccr5 in stromal/endothelial cells was not. Mechanistically, CCL5 promotes hematopoietic cell cycling and cell survival. Like murine hematopoietic cells, human hematopoietic cells (cord blood, healthy marrow, and peripheral blood) increase CCR5 expression after radiation exposure to promote cell survival. These data establish that CCL5 and CCR5 signaling play critical roles in hematopoietic regeneration and could serve as therapeutic targets to shorten the duration of myelosuppression.

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CCL5 and CCR5 expression in the bone marrow is increased following radiation

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CCL5 promotes cell cycling and survival after irradiation

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CCR5 is necessary for hematopoietic regeneration

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CCL5 can shorten the duration of myelosuppression following total body radiation

The effects of short-term use of granulocyte colony-stimulating factor on bone metabolism in child cancer patients

OBJECTIVE:

The granulocyte colony-stimulating factor (G-CSF) is the most commonly used hematopoietic growth factor recombinant DNA technology. It affects bone metabolism by modulating both osteoclast and osteoblast functions. The aim of the present study was to investigate the effects of short-term use of G-CSF on bone metabolism in children with leukemia and solid tumors.

METHODS:

Thirty-six patients with a malignancy who received G-CSF therapy according to chemotherapy protocols and another 20 growth factor-free cancer patients who were enrolled as controls were included in the study. The serum osteocalcin and urinary free deoxypyridinoline levels were measured before the start of G-CSF therapy, on day 3 after treatment, and 7 days after G-CSF therapy was discontinued. In the control group, the measurements were made during corticosteroid and methotrexate-free chemotherapy.

RESULTS:

The mean osteocalcin level (8.6±2.3 ng/mL) from before the onset of treatment decreased significantly (7.7±2.3 ng/mL) on day 3 of G-CSF therapy and significantly increased after 7 days of G-CSF therapy (7.9±2.2 ng/mL) (p<0.001 and p<0.001, respectively), which was still significantly lower than the pre-G-CSF values (p<0.001). The urinary free deoxypyridinoline level significantly increased on day 3 of G-CSF treatment (25.6±6.5 nmol/mmol Cr) and significantly decreased after 7 days of G-CSF therapy (22.6±6.4 nmol/mmol Cr) (p<0.001 and p<0.001, respectively), which was still significantly higher than the values recorded before G-CSF therapy (p<0.001).

CONCLUSION:

The findings show that the short-term use of G-CSF in children with cancer can affect bone metabolism and can play a role in metabolic changes. Decreased osteoblastic activity and increased osteoclastic activity suggest that osteoporosis may be associated with bone pain in these patients.

Neuroprotective effects of erythropoietin on rat retinas subjected to oligemia

OBJECTIVES

Erythropoietin may have neuroprotective potential after ischemia of the central nervous system. Here, we conducted a study to characterize the protective effects of erythropoietin on retinal ganglion cells and gliotic reactions in an experimentally induced oligemia model.

METHODS

Rats were subjected to global oligemia by bilateral common carotid artery occlusion and then received either vehicle or erythropoietin via intravitreal injection after 48 h; they were euthanized one week after the injection. The densities of retinal ganglion cells and contents of glial fibrillary acidic protein (astrocytes/Müller cells) and cluster of differentiation 68 clone ED1 (microglia/macrophages), assessed by fluorescence intensity, were evaluated in frozen retinal sections by immunofluorescence and epifluorescence microscopy.

RESULTS

Retinal ganglion cells were nearly undetectable one week after oligemia compared with the sham controls; however, these cells were partially preserved in erythropoietin-treated retinas. The contents of glial fibrillary acidic protein and cluster of differentiation 68 clone ED1, markers for reactive gliosis, were significantly higher in retinas after bilateral common carotid artery occlusion than those in both sham and erythropoietin-treated retinas.

CONCLUSIONS

The number of partially preserved retinal ganglion cells in the erythropoietin-treated group suggests that erythropoietin exerts a neuroprotective effect on oligemic/ischemic retinas. This effect could be related to the down-modulation of glial reactivity, usually observed in hypoxic conditions, clinically observed during glaucoma or retinal artery occlusion conditions. Therefore, glial reactivity may enhance neurodegeneration in hypoxic conditions, like normal-tension glaucoma and retinal ischemia, and erythropoietin is thus a candidate to be clinically applied after the detection of decreased retinal blood flow.

History and Outcome of Febrile Neutropenia Outside the Oncology Setting: A Retrospective Study of 76 Cases Related to Non-Chemotherapy Drugs

BACKGROUND

Despite major advances in its prevention and treatment, febrile neutropenia remains a most concerning complication of cancer chemotherapy. Outside the oncology setting, however, only few data are currently available on febrile neutropenia related to non-chemotherapy drugs. We report here data on 76 patients with febrile neutropenia related to non-chemotherapy drugs, followed up in a referral center within a university hospital.

PATIENTS AND METHODS

Data from 76 patients with idiosyncratic drug-induced febrile neutropenia were retrospectively reviewed. All cases were extracted from a cohort study on agranulocytosis conducted at the Strasbourg University Hospital (Strasbourg, France).

RESULTS

Mean patient age was 52.2 years old (range: 18-93) and gender ratio (F/M) 1.6, with several comorbidities present in 86.8% of patients. The most common causative drugs were: antibiotics (37.4%), antithyroid drugs (17.2%), neuroleptic and anti-epileptic agents (13.1%), non-steroidal anti-inflammatory agents and analgesics (8%), and platelet aggregation inhibitors (8%). Main clinical presentations upon hospitalization included isolated fever (30%), sore throat, acute tonsillitis and sinusitis (18.4%), documented pneumonia (18.4%), septicemia (14.5%), and septic shock (6.6%). Mean neutrophil count at nadir was 0.13 × 10(9)/L (range: 0-0.48). While in hospital, 22 patients (28.9%) worsened clinically and required intensive care unit placement. All patients were promptly treated with broad-spectrum antibiotics, and 45 (59.2%) with hematopoietic growth factors. Mean duration of hematological recovery (neutrophil count ≥1.5 × 10(9)/L) was 7.5 days (range: 2-21), which was reduced to 0.7 days (range: 2-16) (p = 0.089) with hematopoietic growth factors. Outcome was favorable in 89.5% of patients, whereas eight died.

CONCLUSIONS

Like in oncology and myelosuppressive chemotherapy settings, idiosyncratic febrile neutropenia is typically serious, about 40% of patients exhibiting severe pneumonia, septicemia, and septic shock, with a mortality rate of 10%. Like in febrile, chemotherapy-related neutropenia, modern and timely management (immediate broad spectrum antibiotherapy, hematopoietic growth factors) may reduce infection-related mortality. All practitioners should be aware of this potential side-effect that may even occur in the event of "daily medication" exposure.

Non-chemotherapy drug-induced neutropenia - an update

INTRODUCTION

To date, non-chemotherapy drug-induced severe neutropenia (neutrophil count of ≤0.5 x 10⁹/L) also called idiosyncratic drug-induced agranulocytosis is little discussed in the literature. In the present paper, we report and discuss the clinical data and management of this rare disorder. Areas covered: To do this, we carried out a review of the literature using PubMed database of the US National Library of Medicine. We also used data from the American Society of Hematology educational books, textbooks of Hematology and Internal medicine, and information gleaned from international meetings. Expert opinion: Idiosyncratic agranulocytosis remains a potentially serious adverse event due to the frequency of severe sepsis with severe deep tissue infections (e.g., pneumonia), septicemia, and septic shock in approximately two-thirds of all hospitalized patients. In this context, several prognostic factors have been identified that may be helpful when identifying 'susceptible' patients. Old age (>65 years), septicemia or shock, renal failure, and a neutrophil count ≤0.1 × 10⁹/L have been consensually accepted as poor prognostic factors. In our experience, modern management with pre-established procedures, intravenous broad-spectrum antibiotics and hematopoietic growth factors (particularly G-CSF) is likely to improve the prognosis. Thus with appropriate management, the mortality rate is currently between 5 to 10%.

Anti-infective prophylaxis in pediatric patients with acute myeloid leukemia

Pediatric patients undergoing treatment for acute myeloid leukemia (AML) are at high risk for infectious complications, predominantly due to Gram-negative bacteria, viridans group streptococci and fungal pathogens. In order to prevent infections in these patients, most institutions have implemented a number of non-pharmacological approaches to supportive care. In addition, antibiotic prophylaxis reduces bacterial infection, but may increase the emergence of resistance. Antifungal prophylaxis is generally recommended for children with AML. Whereas the use of hematopoietic growth factors has not resulted in improved survival, the efficacy of prophylactic granulocyte transfusions has to be determined.

In vivo administration of granulocyte colony-stimulating factor restores long-term depression in hippocampal slices prepared from transgenic APP/PS1 mice

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine that also possesses neurotrophic and antiapoptotic properties. G-CSF has been reported to decrease amyloid burden significantly, promote hippocampal neurogenesis, and improve spatial learning in a mouse model of Alzheimer's disease. To understand better the effects of G-CSF on hippocampal-dependent learning, the present study focused on electrophysiological correlates of neuroplasticity, long-term potentiation (LTP), and long-term depression (LTD). Two cohorts of transgenic APP/PS1 mice, with or without prior bone marrow transplantation from Tg GFP mice, were treated in vivo for 2 weeks with G-CSF or vehicle. After completion of the treatments, hippocampal slices were prepared for electrophysiological studies of LTP and LTD. LTP was induced and maintained in both G-CSF-treated and vehicle-treated groups of Tg APP/PS1. In contrast, LTD could not be induced in vehicle-treated Tg APP/PS1 mice, but G-CSF treatment restored LTD. The LTP and LTD results obtained from the cohort of bone marrow-grafted Tg APP/PS1 mice did not differ from those from nongrafted Tg APP/PS1 mice. The mechanism by which G-CSF restores LTD is not known, but it is possible that its capacity to reduce amyloid plaques results in increased soluble oligomers of amyloid-β (A-β), which in turn may facilitate LTD. This mechanism would be consistent with the recent report that soluble A-β oligomers promote LTD in hippocampal slices.

Granulocyte colony-stimulating factor in patients with acute ischemic stroke: results of the AX200 for Ischemic Stroke trial

BACKGROUND AND PURPOSE

Granulocyte colony-stimulating factor (G-CSF; AX200; Filgrastim) is a stroke drug candidate with excellent preclinical evidence for efficacy. A previous phase IIa dose-escalation study suggested potential efficacy in humans. The present large phase IIb trial was powered to detect clinical efficacy in acute ischemic stroke patients.

METHODS

G-CSF (135 µg/kg body weight intravenous over 72 hours) was tested against placebo in 328 patients in a multinational, multicenter, randomized, and placebo-controlled trial (NCT00927836; www.clinicaltrial.gov). Main inclusion criteria were ≤9-hour time window after stroke onset, infarct localization in the middle cerebral artery territory, baseline National Institutes of Health Stroke Scale score range of 6 to 22, and baseline diffusion-weighted imaging lesion size ≥15 mL. Primary and secondary end points were the modified Rankin scale score and the National Institutes of Health Stroke Scale score at day 90, respectively. Data were analyzed using a prespecified model that adjusted for age, National Institutes of Health Stroke Scale score at baseline, and initial infarct volume (diffusion-weighted imaging).

RESULTS

G-CSF treatment failed to meet the primary and secondary end points of the trial. For additional end points such as mortality, Barthel index, or infarct size at day 30, G-CSF did not show efficacy either. There was, however, a trend for reduced infarct growth in the G-CSF group. G-CSF showed the expected peripheral pharmacokinetic and pharmacodynamic profiles, with a strong increase in leukocytes and monocytes. In parallel, the cytokine profile showed a significant decrease of interleukin-1.

CONCLUSIONS

G-CSF, a novel and promising drug candidate with a comprehensive preclinical and clinical package, did not provide any significant benefit with respect to either clinical outcome or imaging biomarkers.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00927836.

Recombinant Human Erythropoietin: Novel Strategies for Neuroprotective/Neuro-regenerative Treatment of Multiple Sclerosis

Treatment of multiple sclerosis (MS) is still unsatisfactory and essentially non-existing for the progressive course of the disease. Recombinant human erythropoietin (EPO) may be a promising neuroprotective/neuroregenerative treatment of MS. In the nervous system, EPO acts anti-apoptotic, antioxidative, anti-inflammatory, neurotrophic and plasticity-modulating. Beneficial effects have been shown in animal models of various neurological and psychiatric diseases, including different models of experimental autoimmune encephalomyelitis. EPO is also effective in human brain disease, as shown in double-blind placebo-controlled clinical studies on ischemic stroke and chronic schizophrenia. An exploratory study on chronic progressive MS yielded lasting improvement in motor and cognitive performance upon high-dose long-term EPO treatment.

Pivotal role for the NFIL3/E4BP4 transcription factor in interleukin 3-mediated survival of pro-B lymphocytes

The E2A-HLF (hepatic leukemia factor) oncoprotein, generated in pro-B lymphocytes by fusion of the trans-activation domain of E2A to the basic region/leucine zipper (bZIP) domain of HLF, functions as an anti-apoptotic transcription factor in leukemic cell transformation. When introduced into interleukin 3 (IL-3)-dependent mouse pro-B lymphocytes, E2A-HLF prevents apoptosis induced by growth factor deprivation, suggesting that IL-3 mediates cell survival through activation of a transcription factor whose activity can be constitutively replaced by the chimeric oncoprotein. We considered four bZIP transcription factors as candidates for this putative IL-3-regulated factor, each of which binds avidly to the DNA consensus sequence recognized by E2A-HLF and is related to the Caenorhabditis elegans CES-2 (cell death specification protein) neuron-specific mediator of cell death. The expression and binding activity of the Nfil3 protein (also called E4bp4), but not of Hlf, Dbp, or Tef, was found to be regulated by IL-3 in mouse pro-B cell lines (Baf-3 and FL5.12). Northern blot analysis showed that Nfil3/E4bp4 is regulated as a "delayed-early" IL-3-responsive gene, requiring de novo protein synthesis. In the absence of IL-3, enforced expression of the human NFIL3/E4BP4 cDNA promoted the survival but not the growth of IL-3-dependent pro-B cells. Our results implicate NFIL3/E4BP4 (nuclear factor regulated by IL-3/adenovirus E4 promoter binding protein) in a distinct growth factor-regulated signaling pathway that is responsible for the survival of early B-cell progenitors, and whose alteration by E2A-HLF leads to childhood B lineage leukemia.

Hematopoietic Growth Factors and Blast Progenitors in Acute Leukemia

Leukemic cells are maintained by a minor subpopulation of cells called leukemic stem cells (LSC) with proliferative and self-renewal capacity, both of which are detected with leukemic colony assay, with the latter being an important prognositic factor. Drug sensitivity tests employing leukemic colony assay revealed the effects of cytotoxic drugs on LSC to be diverse and that cytosine arabinoside predominantly suppresses self-renewal, which probably accounts for its effectiveness in AML therapy. Hematopoietic growth factors (HGFs) regulate the growth of LSC and various in vitro effects of HGFs on acute leukemia cells have been reported. These effects appear to reflect physiological functions of each HGF and can be categorized into groups according to their distinct functions. Endogenously produced HGFs stimulate LSC in an autocrine or a paracrine fashion, resulting in autonomous growth of these cells, which also correlates with the patients' prognosis. HGFs can enhance the cytotoxicity of anti-leukemia drugs in vitro, possibly mainly through recruitment of LSC from the dormant state into active cell cycling. HGFs have been clinically tested in leukemia therapy. Although recovery of blood leukocyte counts can consistently be accelerated with HGF treatment, the effectiveness of HGFs in sensitizing leukemia cells to chemotherapeutic agents and/or improving patient prognosis has not been clearly demonstrated. Different strategies using HGFs and related molecules must be tested in future leukemia therapy.

Tyrosine phosphorylation of the proto-oncogene product Vav and its association with the adapter Grb2/Ash in a human leukemia cell line UT-7

The vav proto-oncogene product (Vav) is expressed exclusively in hematopoietic cells and is reported to have guanine nucleotide exchange activity. Here we report that granulocyte-macrophage colony-stimulating factor, interleukin-3, and erythropoietin induce tyrosine phosphorylation of Vav in a human leukemia cell line UT-7. Tyrosine phosphorylation of Vav is rapid and transient; it occurs within 1 min of the stimulation and at physiological concentrations of the factors. Furthermore, we show that Vav is constitutively associated with the adapter molecule Grb2/Ash in UT-7. These data suggest that tyrosine kinases, the adapter Grb2/Ash, and the guanine nucleotide exchange factor Vav are members of a signaling pathway leading to Ras activation in hematopoietic cells.