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Malvar G, Gunasekaran D, Mehr NV, Ishibe S, Moeckel G. Thrombotic Microangiopathy and Acute Tubular Injury After Diethylene Glycol Ingestion: A Kidney Biopsy Teaching Case. Kidney Med 2024; 6:100758. [PMID: 38304581 PMCID: PMC10831151 DOI: 10.1016/j.xkme.2023.100758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024] Open
Abstract
We present a rare and unusual case of thrombotic microangiopathy (TMA) in a patient who ingested chafing fuel containing diethylene glycol. The patient showed a typical clinical course of initial gastrointestinal symptoms followed by acute kidney injury (AKI) and peripheral sensorimotor neuropathy. A kidney biopsy showed TMA and diffuse acute tubular injury. Diethylene glycol is widely used as a solvent in numerous consumer products, including brake fluid, antifreeze, chafing fuel, and artificial fog solutions. Diethylene glycol has been implemented in mass poisonings, and the incidence of AKI in diethylene glycol poisonings is linked to high-mortality rates. TMA, a pathologic lesion observed in a wide spectrum of diseases, is triggered by endothelial injury. Our case shows that TMA should be considered as a possible life-threatening complication in the setting of acute diethylene glycol poisoning. Direct toxic injury to endothelial cells by diethylene glycol is a possible mechanism. It is therefore plausible that patients with a genetic predisposition to endothelial injury may develop TMA following diethylene glycol exposure.
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Affiliation(s)
- Grace Malvar
- Department of Pathology, Yale University School of Medicine, New Haven, CT
| | | | | | - Shuta Ishibe
- Department of Medicine, Yale University School of Medicine, New Haven, CT
| | - Gilbert Moeckel
- Department of Pathology, Yale University School of Medicine, New Haven, CT
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Tobin JD, Jamison CN, Robinson CN, McMartin KE. Variable sensitivity to diethylene glycol poisoning is related to differences in the uptake transporter for the toxic metabolite diglycolic acid. Clin Toxicol (Phila) 2023; 61:207-211. [PMID: 36939119 PMCID: PMC10263375 DOI: 10.1080/15563650.2022.2163659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 12/19/2022] [Accepted: 12/24/2022] [Indexed: 03/21/2023]
Abstract
INTRODUCTION/CONTEXT Poisonings with diethylene glycol are characterized by acute kidney injury and peripheral neuropathy. In animal studies on the toxicities of diethylene glycol and its metabolite diglycolic acid, remarkable differences in susceptibility to acute kidney injury were observed in identically-dosed rats. In those studies, only about 60% showed acute kidney injury, yet all rats with acute kidney injury showed marked diglycolic acid accumulation in tissues, while no diglycolic acid accumulated in rats without injury. Diglycolic acid is taken into renal cells via sodium-dependent dicarboxylate transporters. When sodium-dependent dicarboxylate transporter-1 is inhibited or knocked down in human kidney cells, diglycolic acid uptake and toxicity are reduced. We hypothesize that the variation in sensitivity to tissue diglycolic acid retention and to diethylene glycol/diglycolic acid toxicity is explained by differential expression of sodium-dependent dicarboxylate transporter-1 in rat kidneys. METHODS Using kidney tissue from previous studies, we performed rt-PCR analysis of sodium-dependent dicarboxylate transporter-1 mRNA. In those studies, Wistar-Han rats were either gavage with diethylene glycol 6 g/kg every 12 h for 7 days or with single doses of diglycolic acid 300 mg/kg. Kidney tissue was harvested after euthanasia and preserved in formalin. Tissue slices were homogenized and RNA was isolated using an RNAstorm FFPE RNA Isolation Kit. The expression of sodium-dependent dicarboxylate transporter-1 mRNA was compared between groups that showed diglycolic acid accumulation and acute renal injury with those that showed no diglycolic acid accumulation or toxicity. RESULTS Significantly higher expression of sodium-dependent dicarboxylate transporter-1 mRNA was present in the kidneys of rats with acute kidney injury and diglycolic acid accumulation compared to those in rats that had no diglycolic acid in their kidneys and no acute kidney injury. DISCUSSION The likelihood of acute kidney injury after dosing of rats with diethylene glycol or diglycolic acid is linked with an enhanced ability to take up diglycolic acid into renal cells via the sodium-dependent dicarboxylate transporter-1. The variability in diethylene glycol toxicity in humans, as reported in epidemiological studies, may also be linked with differences in tissue uptake of diglycolic acid. CONCLUSIONS Animals with acute kidney injury after exposure to diethylene glycol or diglycolic acid had higher sodium-dependent dicarboxylate transporter-1 expression and greater diglycolic acid accumulation in renal tissues than animals without acute kidney injury.
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Affiliation(s)
- Julie D Tobin
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Courtney N Jamison
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Corie N Robinson
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Kenneth E McMartin
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
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Tobin JD, Robinson CN, Luttrell-Williams ES, Landry GM, McMartin KE. Lack of efflux of diglycolic acid from proximal tubule cells leads to its accumulation and to toxicity of diethylene glycol. Toxicol Lett 2023; 379:48-55. [PMID: 36958672 DOI: 10.1016/j.toxlet.2023.03.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/07/2023] [Accepted: 03/16/2023] [Indexed: 03/25/2023]
Abstract
Diethylene glycol (DEG) mass poisonings have resulted from ingestion of adulterated pharmaceuticals, leading to proximal tubular necrosis and acute kidney injury. Diglycolic acid (DGA), one of the primary metabolites, accumulates greatly in kidney tissue and its direct administration results in toxicity identical to that in DEG-treated rats. DGA is a dicarboxylic acid, similar in structure to Krebs cycle intermediates such as succinate. Previous studies have shown that DGA is taken into kidney cells via the succinate-related dicarboxylate transporters. These studies have assessed whether the DGA that is taken up by primary cultures of human proximal tubule (HPT) cells is effluxed. In addition, a possible mechanism for efflux, via organic anion transporters (OATs) that exchange external organic anions for dicarboxylates inside the cell, was assessed using transformed cell lines that actively express OAT activities. When HPT cells were cultured on membrane inserts, then loaded with DGA and treated with the OAT4/5 substrate estrone sulfate or the OAT1/3 substrate para-aminohippurate, no DGA efflux was seen. A repeat of this experiment utilizing RPTEC/TERT1 cells with overexpressed OAT1 and OAT3 had similar results. In these cells, but not in HPT cells, co-incubation with succinate increased the uptake of PAH, confirming the presence of OAT activity in the RPTEC/TERT1 cells. Thus, despite OATs stimulation in cells with OAT activity, there was little to no efflux of DGA from the cells. This study concluded that DGA is poorly transported out of cells and that stimulation of OAT transporters is not a viable target for reducing DGA accumulation in cells.
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Affiliation(s)
- Julie D Tobin
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130
| | - Corie N Robinson
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130
| | - Elliot S Luttrell-Williams
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130
| | - Greg M Landry
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130
| | - Kenneth E McMartin
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport, Shreveport, Louisiana 71130.
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Reed KJ, Landry GM. Diglycolic acid inhibits succinate dehydrogenase activity, depletes mitochondrial membrane potential, and induces inflammation in an SH-SY5Y neuroblastoma model of neurotoxicity in vitro. Toxicol Appl Pharmacol 2023; 463:116414. [PMID: 36754214 DOI: 10.1016/j.taap.2023.116414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/08/2023]
Abstract
Diethylene glycol is a toxic industrial solvent resulting in a well-defined toxidrome. Diglycolic acid (DGA) has been identified as the metabolite responsible for the nephrotoxicity and hepatotoxicity. These studies assess the mechanism of DGA-induced neurotoxicity, specifically addressing the known ability of DGA to chelate calcium (Ca2+) in solution and inhibit mitochondrial complex II. SH-SY5Y cells were seeded into 96-well plates to assess intracellular Ca2+ chelation, complex II activity, mitochondrial membrane potential (ΔΨm), ATP production, and release of inflammatory cytokines TNF-α and IL-1β with 2-, 4-, 6-, 24-, and 48-h DGA exposure. Peak Ca2+ chelation occurred at 4 h in cells treated with 6.25-50 mM DGA; however, effects were transient. Complex II activity was significantly decreased at all DGA concentrations tested, with 12.5 mM DGA causing 80% inhibition and 25 and 50 mM DGA causing 97 and 100% inhibition, respectively. Subsequently, 12.5-50 mM DGA concentrations significantly decreased ΔΨm at all time points. 50 mM DGA significantly increased release of TNF-α and IL-1β after 24 and 48 h with significantly decreased ATP production observed at the same time points and concentration. These studies demonstrate that the DGA-induced mechanism of SH-SY5Y cell death involves complex II inhibition leading to mitochondrial depolarization, and subsequent ATP depletion with accompanying inflammatory cytokine release. These results indicate a direct mechanism of DGA-induced neurotoxicity in vitro, similarly observed in other DEG-affected target organs.
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Affiliation(s)
- Kristi J Reed
- Massachusetts College of Pharmacy and Health Sciences, School of Pharmacy, Department of Pharmaceutical Sciences, Boston, MA 02115, United States
| | - Greg M Landry
- Massachusetts College of Pharmacy and Health Sciences, School of Pharmacy, Department of Pharmaceutical Sciences, Boston, MA 02115, United States.
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Tobin JD, Robinson CN, Luttrell-Williams ES, Landry GM, Dwyer D, McMartin KE. Role of plasma membrane dicarboxylate transporters in the uptake and toxicity of diglycolic acid, a metabolite of diethylene glycol, in human proximal tubule cells. Toxicol Sci 2022; 190:1-12. [PMID: 36087010 DOI: 10.1093/toxsci/kfac091] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Diethylene glycol (DEG) mass poisonings have resulted from ingestion of pharmaceuticals mistakenly adulterated with DEG, typically leading to proximal tubular necrosis and acute kidney injury. The metabolite, diglycolic acid (DGA) accumulates greatly in kidney tissue and its direct administration results in toxicity identical to that in DEG-treated rats. DGA is a dicarboxylic acid, similar in structure to metabolites like succinate. These studies have assessed the mechanism for cellular accumulation of DGA, specifically whether DGA is taken into primary cultures of human proximal tubule (HPT) cells via sodium dicarboxylate transporters (NaDC-1 or NaDC-3) like those responsible for succinate uptake. When HPT cells were cultured on membrane inserts, sodium dependent succinate uptake was observed from both apical and basolateral directions. Pretreatment with the NaDC-1 inhibitor N-(p-amylcinnamoyl)anthranilic acid (ACA) markedly reduced apical uptakes of both succinate and DGA. Basolateral uptake of both succinate and DGA were decreased similarly following combined treatment with ACA and the NaDC-3 inhibitor 2,3-dimethylsuccinate. When the cells were pre-treated with siRNA to knockdown NaDC-1 function, apical uptake of succinate and toxicity of apically applied DGA were reduced, while the reduction in basolateral succinate uptake and basolateral DGA toxicity was marginal with NaDC-3 knockdown. DGA reduced apical uptake of succinate, but not basolateral uptake. This study confirmed that primary HPT cells retain sodium dicarboxylate transport functionality and that DGA was taken up by these transporters. This study identified NaDC-1 as a likely and NaDC-3 as a possible molecular target to reduce uptake of this toxic metabolite by the kidney.
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Affiliation(s)
- Julie D Tobin
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
| | - Corie N Robinson
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
| | - Elliot S Luttrell-Williams
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
| | - Greg M Landry
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
| | - Donard Dwyer
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130.,Department of Psychiatry and Behavioral Medicine, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
| | - Kenneth E McMartin
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center-Shreveport Shreveport, Louisiana, 71130
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Histopathological evidence that diethylene glycol produces kidney and nervous system damage in rats. Neurotoxicology 2022; 91:200-210. [DOI: 10.1016/j.neuro.2022.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 04/14/2022] [Accepted: 05/20/2022] [Indexed: 11/21/2022]
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Jamison CN, Dayton RD, Latimer B, McKinney MP, Mitchell HG, McMartin KE. Diethylene glycol produces nephrotoxic and neurotoxic effects in female rats. Clin Toxicol (Phila) 2022; 60:324-331. [PMID: 34278906 PMCID: PMC9661884 DOI: 10.1080/15563650.2021.1953049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
CONTEXT Diethylene glycol (DEG) is an organic compound found in household products but also as a counterfeit solvent in medicines. DEG poisonings are characterized by acute kidney injury (AKI) and by neurological sequelae such as decreased reflexes or face and limb weakness. Previous studies in male rats have demonstrated that neurotoxic effects develop only with the establishment of AKI, but the dose sensitivity of females to DEG toxicity is unknown. OBJECTIVES Assessing whether subacute administration of DEG in female rats would delineate any sex-differences in neuropathy or in kidney injury. METHODS Female Wistar-Han rats were orally administered doses of 4 - 6 g/kg DEG every 12 h and monitored for 7 days. Urine was collected every 12 h and endpoint blood and cerebrospinal fluid (CSF) were collected for renal plasma parameters and total protein estimation, respectively. Motor function tests were conducted before and after treatment. Kidney and brain tissue were analyzed for metabolite content. RESULTS Of 12 animals treated with DEG, 3 developed AKI as confirmed by increased BUN and creatinine concentrations. Renal and brain DGA contents were increased in animals that developed AKI compared to animals without AKI. Total CSF protein content in animals with AKI was markedly elevated compared to control and to treated animals without AKI. Decreases in forelimb grip strength and in locomotor and rearing activity were observed in animals with AKI compared to control and to animals without AKI. DISCUSSION Repeated dosing with DEG in a female model produced nephrotoxic effects at a dose similar to that in males. The decrease in motor function and increase in CSF protein were only present in females that developed AKI. However, kidney and neurologic effects were assessed only at the end of the treatments, thus limiting determination of which effect occurs first. Limb function and coordination were measured globally and more sensitive tests such as nerve conduction studies might offer a detailed neurotoxicity assessment of the effects of DEG. CONCLUSIONS These studies show that DEG toxicity does not appear to be sex-specific and that, in males and females, neurological symptoms are present only when DGA accumulation and kidney injury also occur.
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Affiliation(s)
- Courtney N. Jamison
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Robert D. Dayton
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Brian Latimer
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Mary P. McKinney
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Hannah G. Mitchell
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Kenneth E. McMartin
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
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Reed KJ, Freeman DT, Landry GM. Diethylene glycol and its metabolites induce cell death in SH-SY5Y neuronal cells in vitro. Toxicol In Vitro 2021; 75:105196. [PMID: 34022404 DOI: 10.1016/j.tiv.2021.105196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/04/2021] [Accepted: 05/15/2021] [Indexed: 01/07/2023]
Abstract
Diethylene glycol (DEG) intoxication results in metabolic acidosis, renal and hepatic dysfunction, and late-stage neurotoxicity. Though the renal and hepatic toxicity of DEG and its metabolites 2-hydroxyethoxyacetic acid (2-HEAA) and diglycolic acid (DGA) have been well characterized, the resultant neurotoxicity has not. SH-SY5Y neuroblastoma cells were incubated with all 3 compounds at increasing concentrations for 24, 48, or 120 h. At all 3 time points, 50 mmol/L DGA and 100 mmol/L DEG showed significant Annexin V and propidium iodide (PI) staining with additional concentrations showing similar staining patterns at 24 h (100 mmol/L DGA) and 48 h (50 mmol/L DEG, 100 mmol/L DGA). Only the 200 mmol/L 2-HEAA concentration induced SH-SY5Y cell death. Interestingly at 24 and 48 h, 100 mmol/L DEG induced significant increases in apoptotic cell death markers, which progressed to necrosis at 120 h. Similar to DEG, 50 mmol/L DGA induced significant increases in SH-SY5Y cell apoptosis and necrosis markers at both 24 and 48 h. As expected, high DGA concentrations (100 mmol/L) at 120 h induced significant SH-SY5Y cell necrosis with no apoptosis detected. However, at 120 h lower DGA concentrations (20 mmol/L) significantly increased oligonucleosome formation alone and in combination with 2-HEAA or DEG. Taken together, these results indicate that DGA and DEG at threshold concentrations induce neurotoxicity in SH-SY5Y cells.
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Affiliation(s)
- Kristi J Reed
- MCPHS University, School of Pharmacy, Department of Pharmaceutical Sciences, Boston, MA 02115, United States
| | - Dylan T Freeman
- MCPHS University, School of Pharmacy, Department of Pharmaceutical Sciences, Boston, MA 02115, United States
| | - Greg M Landry
- MCPHS University, School of Pharmacy, Department of Pharmaceutical Sciences, Boston, MA 02115, United States.
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Jamison CN, Dayton RD, Latimer B, McKinney MP, Mitchell HG, McMartin KE. Neurotoxic effects of nephrotoxic compound diethylene glycol. Clin Toxicol (Phila) 2021; 59:810-821. [PMID: 33475432 DOI: 10.1080/15563650.2021.1874403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
CONTEXT Diethylene glycol (DEG) is an organic compound found in household products but also as an adulterant in medicines by acting as a counterfeit solvent. DEG poisonings have been characterized predominately by acute kidney injury (AKI), but also by delayed neurological sequelae such as decreased reflexes or face and limb weakness. OBJECTIVES Characterizing the neurological symptoms of DEG poisoning in a subacute animal model would create a clearer picture of overall toxicity and possibly make mechanistic connections between kidney injury and neuropathy. METHODS Male Wistar-Han rats were orally administered doses of 4 - 6 g/kg DEG every 12 or 24 h and monitored for 7 days. Urine was collected every 12 h and endpoint blood and cerebrospinal fluid (CSF) were collected for a renal plasma panel and total protein estimation, respectively. Motor function tests were conducted before and after treatment. Kidney and brain tissue was harvested for metabolic analysis. RESULTS Of the 43 animals treated with DEG, 11 developed AKI as confirmed by increased BUN and creatinine levels. Renal and brain DGA accumulation was markedly increased in animals that developed AKI compared to animals without AKI. The total protein content in CSF in animals with kidney injury was markedly elevated compared to control and to treated animals without AKI. Significant decreases in forelimb grip strength and decreases in locomotor and rearing activity were observed in animals with AKI compared to control and to animals without AKI. DISCUSSION Repeated dosing with DEG in an animal model produced nephrotoxic effects like those in studies with acute DEG administration. The decrease in motor function and increase in CSF protein were only present in animals that developed AKI. CONCLUSIONS These studies show development of neurotoxicity in this DEG animal model and suggest that neurological symptoms are observed only when DGA accumulation and kidney injury also occur.
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Affiliation(s)
- Courtney N Jamison
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Robert D Dayton
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Brian Latimer
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Mary P McKinney
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Hannah G Mitchell
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
| | - Kenneth E McMartin
- Department of Pharmacology, Toxicology and Neuroscience, LSU Health Sciences Center, Shreveport, LA, USA
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Eckstrum K, Striz A, Ferguson M, Zhao Y, Welch B, Solomotis N, Olejnik N, Sprando R. Utilization of a model hepatotoxic compound, diglycolic acid, to evaluate liver Organ-Chip performance and in vitro to in vivo concordance. Food Chem Toxicol 2020; 146:111850. [DOI: 10.1016/j.fct.2020.111850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 10/23/2022]
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Mossoba ME, Vohra S, Toomer H, Pugh-Bishop S, Keltner Z, Topping V, Black T, Olejnik N, Depina A, Belgrave K, Sprando J, Njorge J, Flynn TJ, Wiesenfeld PL, Sprando RL. Comparison of diglycolic acid exposure to human proximal tubule cells in vitro and rat kidneys in vivo. Toxicol Rep 2017; 4:342-347. [PMID: 28959658 PMCID: PMC5615145 DOI: 10.1016/j.toxrep.2017.06.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/19/2017] [Accepted: 06/22/2017] [Indexed: 01/13/2023] Open
Abstract
Diglycolic acid (DGA) is an indirect food additive. DGA was tested for renal cell toxicity in vitro using HK-2 cells. Evaluation of toxicity included cellular and mitochondrial effects. In vitro data are highly concordant with in vivo outcomes.
Diglycolic acid (DGA) is present in trace amounts in our food supply and is classified as an indirect food additive linked with the primary GRAS food additive carboxymethyl cellulose (CMC). Carboxymethyl starches are used as a filler/binder excipient in dietary supplement tablets and a thickening ingredient in many other processed foods. We sought to utilize the human proximal tubule HK-2 cell line as an in vitro cellular model system to evaluate its acute nephrotoxicity of DGA. We found that DGA was indeed toxic to HK-2 cells in all in vitro assays in our study, including a highly sensitive Luminex assay that measures levels of an in vitro biomarker of kidney-specific toxicity, Kidney Injury Molecule 1 (KIM-1). Interestingly, in vitro KIM-1 levels also correlated with in vivo KIM-1 levels in urine collected from rats treated with DGA by daily oral gavage. The use of in vitro and in vivo models towards understanding the effectiveness of an established in vitro system to predict in vivo outcomes would be particularly useful in rapidly screening compounds that are suspected to be unsafe to consumers. The merit of the HK-2 cell model in predicting human toxicity and accelerating the process of food toxicant screening would be especially important for regulatory purposes. Overall, our study not only revealed the value of HK-2 in vitro cell model for nephrotoxicity evaluation, but also uncovered some of the mechanistic aspects of the human proximal tubule injury that DGA may cause.
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Affiliation(s)
- Miriam E. Mossoba
- Corresponding author at: US FDA, MOD-1 Laboratories, 8301 Muirkirk Rd., HFS-025, Lab 1406, Laurel, MD 20708, United States.
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