Chemical Modulation of 3-Methylindole Toxicosis in Mice: Effect on Bronchiolar and Olfactory Mucosal Injury

Turk, Margaret A.; Flory, W; Henk, William G.

doi:10.1177/030098588602300504

Cited by 38 publications

(16 citation statements)

References 25 publications

(5 reference statements)

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“…This aromatic hydrocarbon is converted to a reactive arene oxide by the P-450 system, and either the parent compound or the metabolite(s) selectively initiates bronchiolar Clara cell necrosis in mice (7). Two other compounds, 4-ipomeanol and 3-methylindole, which also produce extensive Clara cell necrosis in mice (8)(9)(10)(11), are very highly toxic (TD50 value < 0.1 MM) and highly toxic (TD50 = 5 MM), respectively, to Clara cell cultures (Figs. 6 and 7).…”

Section: Effects Of Bronchiolar Toxins On the Plating Efficiency Of Cmentioning

confidence: 99%

Clara Cell Cultures from the Mouse and Their Reaction to Bronchiolar Toxins

Richards¹,

Oreffo²,

Lewis³

1990

Environmental Health Perspectives

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The major aim of this study was to determine if small numbers of freshly isolated mouse Clara cells could be used to rapidly screen the toxic effects of a number of diverse pulmonary toxins. A short-term (20 hr) culture of functionally competent (nitotetrazolium reductase positive) Clara cells was developed. In this culture the Clara cells were allowed to attach to an extracellular matrix in 96-well multiwell plates containing a culture medium of DCCM 1 and Ultroser G (0.4%). Pulmonary toxins (a total of 26 agents with concentrations ranging from 10 -7 M to 10 -3 M) were examined for their ability to reduce the attachment efficiency of functionally competent Clara cells and TD50 values (the amount of toxin required to reduce normal attachment efficiency by 50 %) were calculated. With the possible exception of some halogenated hydrocarbons, the simple toxicity test in vitro correlated well with the known effects of the bronchiolar necrotic agents in vivo. For 13 compounds studied there was a direct correlation between TD50 values in vitro and LD50 values (mostly oral) in rodents in vivo, the correlation coefficient of the regression line being 0.783.

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Section: Effects Of Bronchiolar Toxins On the Plating Efficiency Of Cmentioning

confidence: 99%

Clara Cell Cultures from the Mouse and Their Reaction to Bronchiolar Toxins

Richards¹,

Oreffo²,

Lewis³

1990

Environmental Health Perspectives

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“…3-Methylindole (3MI), a metabolite of tryptophan and a constituent of tobacco smoke, is a selective respiratory tract toxicant in mice (Turk et al, 1986). 3MI can selectively induce necrosis in the bronchiolar epithelial (Clara) cells in the mouse lung (Turk et al, 1984) and necrosis in epithelial cells of Bowman's glands and olfactory sustentacular cells in mouse nasal olfactory mucosa (OM) (Turk et al, 1987;Miller and O'Bryan, 2003).…”

Section: Introductionmentioning

confidence: 99%

Respective Roles of CYP2A5 and CYP2F2 in the Bioactivation of 3-Methylindole in Mouse Olfactory Mucosa and Lung: Studies Using Cyp2a5-Null and Cyp2f2-Null Mouse Models

Zhou

D’Agostino

et al. 2012

Drug Metab Dispos

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ABSTRACT:The aim of this study was to determine whether mouse CYP2A5 and CYP2F2 play critical roles in the bioactivation of 3-methylindole (3MI), a tissue-selective toxicant, in the target tissues, the nasal olfactory mucosa (OM) and lung. Five metabolites of 3MI were identified in NADPH-and GSH-fortified microsomal reactions, including 3-glutathionyl-S-methylindole (GS-A1), 3-methyl-2-glutathionyl-S-indole (GS-A2), 3-hydroxy-3-methyleneindolenine (HMI), indole-3-carbinol (I-3-C), and 3-methyloxindole (MOI). The metabolite profiles and enzyme kinetics of the reactions were compared between OM and lung, and among wild-type, Cyp2a5-null, and Cyp2f2-null mice. In lung reactions, GS-A1, GS-A2, and HMI were detected as major products, and I-3-C and MOI, as minor metabolites. In OM reactions, all five metabolites were detected in ample amounts. The loss of CYP2F2 affected formation of all 3MI metabolites in the lung and formation of HMI, GS-A1, and GS-A2 in the OM. In contrast, loss of CYP2A5 did not affect formation of 3MI metabolites in the lung but caused substantial decreases in I-3-C and MOI formation in the OM. Thus, whereas CYP2F2 plays a critical role in the 3MI metabolism in the lung, both CYP2A5 and CYP2F2 play important roles in 3MI metabolism in the OM. Furthermore, the fate of the reactive metabolites produced by the two enzymes through common dehydrogenation and epoxidation pathways seemed to differ with CYP2A5 supporting direct conversion to stable metabolites and CYP2F2 supporting further formation of reactive iminium ions. These results provide the basis for understanding the respective roles of CYP2A5 and CYP2F2 in 3MI's toxicity in the respiratory tract.

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“…The use of mice was also considered important because of their previous use in a range of pulmonary toxicological studies particularly related to bronchiolar necrosis, with agents such as aromatic hydrocarbons (15), naphthalene (16), paraquat (1? ), or 3-methylindole (18).…”

Section: Introductionmentioning

confidence: 99%

Isolation of Clara Cells from the Mouse Lung

Oreffo¹,

Morgan²,

Richards³

1990

Environmental Health Perspectives

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A method is described for isolating Clara cells from the mouse lung that does not require the technique ofelutriation. Mouse lungs totally perfused ofblood are instilled with crystalline trypsin (0.25 %) and incubated for the optimum time of 15 min. The lung tissue is chopped, mechanically agitated, and sequentially filtered to obtain a primary digest of 3 to 5 x 106 cells. Clara cells, identified routinely by histochemical localization ofNADPH diaphorase, using the stain nitrotetrazolium blue (NBT), accounts for between 20 to 40% of the cells in the primary digest. Layering the cells of the primary digest on a discontinuous Percoll gradient followed by centrifugation gives rise to a major band of cells, 52 % that are Clara cells (0.77 ± 0.28 x 106/mouse). A second method was devised to purify the Clara cells by simply centrifuging (32g, 6 min, 10 OC) the primary digest and discarding the supernatant that contained only a few NBT positive cells. When this process was repeated three times, the final pellet contained 68 % Clara cells realizing 0.55 ± 0.16 x 106 cells/mouse. The cells have typical Clara cell morphology as confirmed by electron microscopy and have a high level ofP-450 enzymes (7-ethoxycoumarin deethylase and coumarin hydroxylase). Furthermore, the primary digests and the purified isolates contain less than 1% alveolar lype II cells, although such cells, identified by the histochemical localization of alkaline phosphatase, can be obtained by a second, more extensive digestion procedure. The simple procedure described for the isolation ofmouse Clara cells could be further advanced if methods could be devised to prevent the loss of NADPH diaphorase activity during enzymatic digestion and cell centrifugation.

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Chemical Modulation of 3-Methylindole Toxicosis in Mice: Effect on Bronchiolar and Olfactory Mucosal Injury

Cited by 38 publications

References 25 publications

Clara Cell Cultures from the Mouse and Their Reaction to Bronchiolar Toxins

Clara Cell Cultures from the Mouse and Their Reaction to Bronchiolar Toxins

Respective Roles of CYP2A5 and CYP2F2 in the Bioactivation of 3-Methylindole in Mouse Olfactory Mucosa and Lung: Studies Using Cyp2a5-Null and Cyp2f2-Null Mouse Models

Isolation of Clara Cells from the Mouse Lung

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