Sodium bicarbonate protects uranium-induced acute nephrotoxicity through uranium-decorporation by urinary alkalinization in rats

Protective effect of Moringa oleifera leaf ethanolic extract against uranyl acetate-induced testicular dysfunction in rats

Uranyl acetate (UA) is used in civilian and military applications, predisposing it to wide dispersion in ecosystems. Using high-performance liquid chromatography, gas chromatography-mass spectrometry, and 2,2-Diphenyl-1-picrylhydrazyl scavenging radical analysis, we confirmed that Moringa oleifera leaf ethanolic extract (MLEE) is rich in biologically active phytochemicals. Thus, this study aims to investigate the possible defensive effect of MLEE against UA-induced testicular dysfunction. To achieve this, rats were divided randomly and evenly into three groups for 14 days. The control group received no treatment, while the UA group received a single intraperitoneal injection of UA at a dose of 5 mg/kg BW dissolved in saline on the 12th day of the experiment, followed by no treatment the following day. The MLEE + UA group received daily oral administration of MLEE (300 mg/kg BW) dissolved in distilled water before exposure to UA intoxication. The disruption observed in the pituitary-gonadal axis of UA-intoxicated rats was characterized by a significant decrease in luteinizing hormone, follicle-stimulating hormone, testosterone, and estradiol 17beta levels. Additionally, there was a notable increase in malondialdehyde and a decrease in catalase, superoxide dismutase, reduced glutathione, and nitric oxide, accompanied by an up-regulation in the immuno-expression of nuclear factor-kappa B, indicating a disturbance in the redox balance. The TUNEL assay confirmed a substantial rise in apoptotic cell numbers in the UA group. Testicular histopathological changes, excessive collagen deposition, and reduced glycogen content were evident following UA exposure. However, supplementation with MLEE effectively countered these mentioned abnormalities. MLEE is proposed to combat the toxicological molecular targets in the UA-affected testis by restoring the balance between oxidants and antioxidants while obstructing the apoptotic cascade. MLEE contains an abundance of redox-stabilizing and cytoprotective phytochemicals that have the potential to counteract the mechanistic pathways associated with UA exposure. These findings encourage further research into other plausible protective aspects of Moringa oleifera against the UA challenge.

Induction of lysosomal exocytosis and biogenesis via TRPML1 activation for the treatment of uranium-induced nephrotoxicity

Uranium (U) is a well-known nephrotoxicant which forms precipitates in the lysosomes of renal proximal tubular epithelial cells (PTECs) after U-exposure at a cytotoxic dose. However, the roles of lysosomes in U decorporation and detoxification remain to be elucidated. Mucolipin transient receptor potential channel 1 (TRPML1) is a major lysosomal Ca2+ channel regulating lysosomal exocytosis. We herein demonstrate that the delayed administration of the specific TRPML1 agonist ML-SA1 significantly decreases U accumulation in the kidney, mitigates renal proximal tubular injury, increases apical exocytosis of lysosomes and reduces lysosomal membrane permeabilization (LMP) in renal PTECs of male mice with single-dose U poisoning or multiple-dose U exposure. Mechanistic studies reveal that ML-SA1 stimulates intracellular U removal and reduces U-induced LMP and cell death through activating the positive TRPML1-TFEB feedback loop and consequent lysosomal exocytosis and biogenesis in U-loaded PTECs in vitro. Together, our studies demonstrate that TRPML1 activation is an attractive therapeutic strategy for the treatment of U-induced nephrotoxicity.

Chelating decorporation agents for internal contamination by actinides: Designs, mechanisms, and advances

During the wide utilization of the actinides in medicine, energy, military, and other fields, internal contaminations can profoundly endanger human health and public security. Chelating decorporation agents are the most effective therapies to reduce internal contamination that includes radiological and chemical toxicities. This review introduces the structures of chelating decorporation agents including inorganic salts, polyaminocarboxylic acids, peptides, polyphosphonates, siderophores, calixarenes, polyethylenimines, and fullerenes, and highlights ongoing advances in their designs and mechanisms. However, there are still numerous challenges that block their applications including coordination properties, pharmacokinetic properties, oral bioavailability, limited timing of administration, and toxicity. Therefore, additional efforts are needed to push novel decorporation agents with high efficiency and low toxicity for the treatment of internal contamination by actinides.

Nuclear and Radiological Emergencies: Biological Effects, Countermeasures and Biodosimetry

Atomic and radiological crises can be caused by accidents, military activities, terrorist assaults involving atomic installations, the explosion of nuclear devices, or the utilization of concealed radiation exposure devices. Direct damage is caused when radiation interacts directly with cellular components. Indirect effects are mainly caused by the generation of reactive oxygen species due to radiolysis of water molecules. Acute and persistent oxidative stress associates to radiation-induced biological damages. Biological impacts of atomic radiation exposure can be deterministic (in a period range a posteriori of the event and because of destructive tissue/organ harm) or stochastic (irregular, for example cell mutation related pathologies and heritable infections). Potential countermeasures according to a specific scenario require considering basic issues, e.g., the type of radiation, people directly affected and first responders, range of doses received and whether the exposure or contamination has affected the total body or is partial. This review focuses on available medical countermeasures (radioprotectors, radiomitigators, radionuclide scavengers), biodosimetry (biological and biophysical techniques that can be quantitatively correlated with the magnitude of the radiation dose received), and strategies to implement the response to an accidental radiation exposure. In the case of large-scale atomic or radiological events, the most ideal choice for triage, dose assessment and victim classification, is the utilization of global biodosimetry networks, in combination with the automation of strategies based on modular platforms.

Protective effects of Polygonatum kingianum polysaccharides and aqueous extract on uranium-induced toxicity in human kidney (HK-2) cells

The current detoxification options of uranium, a toxic radioactive heavy metal, have obvious side effects. Polygonatum kingianum (PK), a natural product with the function of antioxidant, may be effective in detoxification and prevention of uranium-induced nephrotoxicity. Here, we studied the protective effects of PK polysaccharides (PKP) and aqueous extract (PKAE) on uranium-induced toxicity in human kidney (HK-2) cells. First, the physicochemical properties of PKP and PKAE were characterized. Assays on cultured cells demonstrated that pretreatment with PKP and PKAE significantly increased metabolic activity, relieved morphological impairments, and alleviated apoptosis. The impairments caused by uranium exposure were ameliorated (mitochondrial membrane potential and ATP level increased while reactive oxygen species decreased). Molecular mechanistic studies revealed that PKP and PKAE alleviated uranium-induced cytotoxicity by regulating mitochondria-mediated apoptosis and the GSK-3β/Fyn/Nrf2 pathway. Collectively, our data support the preventive and therapeutic applications of PKP and PKAE for uranium poisoning.

Amidoxime-Functionalized Covalent Organic Nanosheets for Sequestration of Uranium In Vivo

Finding efficient actinide decorporation agents is crucial for public health and the development of the nuclear industry. The current inventory of decorporation agents is predominately limited to a handful of ligands. In this work, a two-dimensional (2D) covalent organic nanosheet (CON) material was rationally designed and tested for in vivo uranium decorporation. This material is extensively grafted with amidoxime (AO), a classic uranium-recognition ligand, which not only provides selective binding sites for uranyl but also expands the interlayer spacing of CON, making the active sites more accessible. Significantly, the results of in vivo experiments demonstrate that, in both prophylactic and prompt administration groups, CON-AO exhibits a higher excretion ratio of uranium from kidneys than that of ZnNa₃-diethylenetriamine pentaacetate (DTPA), while presenting a similar level of cytotoxicity. These results suggest that functionalized CONs may emerge as a promising type of actinide in vivo decorporation agent.

In Vivo Uranium Sequestration using a Nanoscale Metal-Organic Framework

An agent for actinide sequestration with fast uranium uptake kinetics and efficient in vivo uranium removal using a nanoscale metal-organic framework (nano-MOF) is proposed. UiO-66 nanoparticles post-synthetically functionalized with carboxyl groups, UiO-66-(COOH)₄ -180, exhibit the fastest uranium uptake kinetics reported with more than 65 % of uranyl in fetal bovine serum (FBS) removed within 5 min. Moreover, the in vivo bio-distribution studies show that the material partially accumulates in kidneys and femurs where uranium mainly deposits facilitating the in vivo sequestration of uranium. The results of the in vivo uranium decorporation assays with mice show that UiO-66-(COOH)₄ -180 could successfully reduce the amounts of uranyl deposited in kidneys and femurs by up to 55.4 % and 36.5 %, respectively, and is significantly more efficient than the commercial actinide decorporation agent, ZnNa₃ -DTPA.

Radioprotection and Radiomitigation: From the Bench to Clinical Practice

The development of protective agents against harmful radiations has been a subject of investigation for decades. However, effective (ideal) radioprotectors and radiomitigators remain an unsolved problem. Because ionizing radiation-induced cellular damage is primarily attributed to free radicals, radical scavengers are promising as potential radioprotectors. Early development of such agents focused on thiol synthetic compounds, e.g., amifostine (2-(3-aminopropylamino) ethylsulfanylphosphonic acid), approved as a radioprotector by the Food and Drug Administration (FDA, USA) but for limited clinical indications and not for nonclinical uses. To date, no new chemical entity has been approved by the FDA as a radiation countermeasure for acute radiation syndrome (ARS). All FDA-approved radiation countermeasures (filgrastim, a recombinant DNA form of the naturally occurring granulocyte colony-stimulating factor, G-CSF; pegfilgrastim, a PEGylated form of the recombinant human G-CSF; sargramostim, a recombinant granulocyte macrophage colony-stimulating factor, GM-CSF) are classified as radiomitigators. No radioprotector that can be administered prior to exposure has been approved for ARS. This differentiates radioprotectors (reduce direct damage caused by radiation) and radiomitigators (minimize toxicity even after radiation has been delivered). Molecules under development with the aim of reaching clinical practice and other nonclinical applications are discussed. Assays to evaluate the biological effects of ionizing radiations are also analyzed.

A review of biological effects and treatments of inhaled depleted uranium aerosol

Depleted uranium (DU) is primarily used for DU bombs and DU tanks in the military. Aerosol inhalation is considered the primary route of DU exposure. Although laboratory tests have confirmed that inhalation of DU aerosol can cause lung, kidney, and other organ damage, epidemiological studies have found no conclusive evidence that persons in areas with prolonged exposure to DU-containing bombs are affected. After the body inhaled DU aerosols, we first clear the insoluble DU through whole-lung lavage (WLL). Then we eliminate the soluble uranium by the chelating agent. Besides, reducing DU damage to tissues and cells through drugs is also an important treatment method. In future research, emphasis should be placed on the damage mechanism of DU aerosol, the laboratory and clinical research of DU chelating agents, the research on the combination of DU chelating agent and WLL, and the research and development of new drugs to prevent DU damage.

The toxicological mechanisms and detoxification of depleted uranium exposure

Depleted uranium (DU) has been widely applied in industrial and military activities, and is often obtained from producing fuel for nuclear reactors. DU may be released into the environment, polluting air, soil, and water, and is considered to exert both radiological and chemical toxicity. In humans and animals, DU can induce multiple health effects, such as renal tubular necrosis and bone malignancies. This review summarizes the known information on DU’s routes of entry, mechanisms of toxicity, and health effects. In addition, we survey the chelating agents used in ameliorating DU toxicity.

Polyethyleneimine methylphosphonate: towards the design of a new class of macromolecular actinide chelating agents in the case of human exposition

Methylphosphonated polyethyleneimine as an interesting candidate to act as a new class of uranyl and plutonium (thorium) decorporation agents.

Pathophysiological role of different tubular epithelial cell death modes in acute kidney injury

The histological substrate of many forms of intrinsic acute kidney injury (AKI) has been classically attributed to tubular necrosis. However, more recent studies indicate that necrosis is not the main form of cell death in AKI and that other forms such as apoptosis, regulated necrosis (i.e. necroptosis and parthanatos), autophagic cell death and mitotic catastrophe, also participate in AKI and that their contribution depends on the cause and stage of AKI. Herein, we briefly summarize the main characteristics of the major types of cell death and we also critically review the existing evidence on the occurrence of different types of cell death reported in the most common experimental models of AKI and human specimens. We also discuss the pathophysiological mechanisms linking tubule epithelial cell death with reduced glomerular filtration, azotaemia and hydroelectrolytic imbalance. For instance, special relevance is given to the analysis of the inflammatory component of some forms of cell death over that of others, as an important and differential pathophysiological determinant. Finally, known molecular mechanisms and signalling pathways involved in each cell death type pose appropriate targets to specifically prevent or reverse AKI, provided that further knowledge of their participation and repercussion in each AKI syndrome is progressively increased in the near future.