Genetic determinants of susceptibility to silver nanoparticle-induced acute lung inflammation in mice.

Silver nanoparticles (AgNPs) are employed in a variety of consumer products; however, in vivo rodent studies indicate that AgNPs can cause lung inflammation and toxicity in a strain- and particle type-dependent manner, but mechanisms of susceptibility remain unclear. The aim of this study was to assess the variation in AgNP-induced lung inflammation and toxicity across multiple inbred mouse strains and to use genome-wide association (GWA) mapping to identify potential candidate susceptibility genes. Mice received doses of 0.25 mg/kg of either 20-nm citrate-coated AgNPs or citrate buffer using oropharyngeal aspiration. Neutrophils in bronchoalveolar lavage fluid (BALF) served as markers of inflammation. We found significant strain- and treatment-dependent variation in neutrophils in BALF. GWA mapping identified 10 significant single-nucleotide polymorphisms (false discovery rate, 15%) in 4 quantitative trait loci on mouse chromosomes 1, 4, 15, and 18, and Nedd4l (neural precursor cell expressed developmentally downregulated gene 4-like; chromosome 18), Ano6 (anocatmin 6; chromosome 15), and Rnf220 (Ring finger protein 220; chromosome 4) were considered candidate genes. Quantitative RT-PCR revealed significant inverse associations between mRNA levels of these genes and neutrophil influx. Nedd4l, Ano6, and Rnf220 are candidate susceptibility genes for AgNP-induced lung inflammation that warrant additional exploration in future studies.-Scoville, D. K., Botta, D., Galdanes, K., Schmuck, S. C., White, C. C., Stapleton, P. L., Bammler, T. K., MacDonald, J. W., Altemeier, W. A., Hernandez, M., Kleeberger, S. R., Chen, L.-C., Gordon, T., Kavanagh, T. J. Genetic determinants of susceptibility to silver nanoparticle-induced acute lung inflammation in mice.

Role of cytochrome P450 2C8 and 2J2 genotypes in calcineurin inhibitor-induced chronic kidney disease.

OBJECTIVES: The calcineurin inhibitors (CNIs) cyclosporine A (CsA) and tacrolimus (Tac) help prevent allograft rejection but are associated with nephrotoxicity. Cytochrome P450 2C8 (CYP2C8) and CYP2J2 are polymorphic enzymes expressed in the kidney that metabolize arachidonic acid (AA) to epoxyeicosatrienoic acids, promoting kidney homeostasis. This study examined the association between CNI-induced nephrotoxicity in liver transplant patients and CYP2C8 and CYP2J2 polymorphisms. METHODS: Liver transplantation patients receiving CNIs for at least 3 years were genotyped for CYP2C8*3, CYP2C8*4, CYP2C8 Haplotypes B and C, and CYP2J2*7 and evaluated for nephrotoxicity (serum creatinine > or = 1.6 mg/dl) 3-year post-transplantation. CYP2C8 proteins were also engineered in E. coli and their activity towards AA and inhibition by CNIs was investigated in vitro. RESULTS: The risk of kidney disease post-transplantation was positively associated with CYP2C8*3 genotype. Odds ratios for all participants carrying at least one CYP2C8*3 allele were significant [odds ratio=2.38 (1.19-4.78)]. Stratification by CNI indicated a significant association between CYP2C8*3 and nephrotoxicity among patients receiving Tac but not CsA. The risk of renal dysfunction was not significantly influenced by CYP2C8*4, CYP2J2*7, or CYP2C8 haplotype B genotypes although inheritance of haplotype C seems to be protective. In vitro, the gene products of CYP2C8*3 and CYP2C8*4 were deficient in AA epoxidation, retaining 26 and 18% of wild-type activity, respectively. Circulating plasma concentrations of CsA and Tac inhibited CYP2C8 wild-type in vitro epoxidation of AA by 17 and 35%, respectively. CONCLUSION: Inheritance of CYP2C8*3 is associated with a higher risk of developing renal toxicity in patients treated chronically with CNIs, and especially Tac, possibly by reducing formation of kidney protecting vasodilatory epoxyeicosatrienoic acids.

Association of estrogen-related polymorphisms with age at menarche, age at final menstrual period, and stages of the menopausal transition.

OBJECTIVE: To explore the association of estrogen-related polymorphisms with age at menarche, age at onset and duration of stages of the menopausal transition, and age at final menstrual period (FMP). DESIGN: A total of 152 white women were genotyped for CYP17, CYP19 3-untranslated region, CYP19 TTTA7-13, HSDB1, CYP1A1, CYP1B1, and ESR1 polymorphisms. Analysis of variance was used to test a nonspecific model for differences among genotypes associated with each polymorphism. RESULTS: Five of the 84 associations tested were significant at P < 0.05, which could be expected by chance. Women with two CYP19 7r alleles had menarche earlier (11.5 y) than those with one 7r allele (13.1 y). Women with two 11r alleles were 2 years older at onset of late stage than those with one 11r allele (50.7 y vs 48.6 y). Those with two 7r(-3) alleles were 2 years older at FMP than those without this allele (53.9 y vs 51.3 y). Women with the homozygous wild-type allele for HSDB1 (rs2830) were younger at FMP by 2 years than those with the heterozygous allele (50.8 y vs 52.9 y). Women with the heterozygous allele for CYP1B1*2 had a later age at menarche compared with women with the homozygous wild type (13 y vs 12.5 y). CONCLUSIONS: Age at onset of late stage and FMP and age at menarche are associated with specific genetic polymorphisms in the estrogen biosynthesis and metabolism genes. However, because of the number of comparisons, these associations may be false positives. These findings should be confirmed with a larger sample of white women.

Cytochrome p450 and glutathione s-transferase mRNA expression in human fetal liver hematopoietic stem cells.

During fetal development, the liver serves as the primary hematopoietic organ in which hematopoietic stem cells (HSC) capable of initiating long-term hematopoiesis comprise a large proportion of the hepatic cell population. Although HSC are potential targets for transplacental chemicals, little is known regarding their xenobiotic biotransformation ability. We quantitated the steady-state mRNA expression of six cytochrome P450 (P450) and 11 glutathione S-transferase (GST) isoforms in CD34(+)-selected HSC isolated from second trimester human fetal liver donors, genotyped donors for polymorphic hGSTM1 and hGSTT1 status, and analyzed gene expression in HSC relative to total liver from donors of similar gestational ages. Several P450 isoforms, including CYP1A1, CYP2E1, CYP3A4, and CYP3A5, were expressed at low levels in HSC (relative mRNA expression CYP3A5 > CYP1A1 > CYP2E1 > CYP3A4). CYP1A2 and CYP3A7 were not detected in HSC. The CYP3A4/5 mRNA expression in HSC was accompanied by detectable CYP3A protein and low midazolam oxidation activity. Several GST isoforms, including hGSTM1, hGSTM2, hGSTM4, and hGSTP1, were significantly higher in HSC as compared with total fetal liver. With the exception of hGSTA4, alpha class GST were not detected in HSC. GST expression in HSC was accompanied by substantial GST catalytic activity toward 1-chloro-2,4-dinitrobenzene. In summary, our data indicate that fetal liver CD34(+)-derived HSC constitutively express several P450 isoforms at low levels relative to total hepatic cell populations but have a higher capacity for GST conjugation reactions through mu and pi class isoforms. The functional ramifications of these observations are discussed relative to the sensitivity of human fetal HSC to transplacental chemical injury.

Polymorphisms in the estrogen synthesis and metabolism pathways and symptoms during the menopausal transition: observations from the Seattle Midlife Women's Health Study.

OBJECTIVE: The purpose of this study was to determine whether polymorphisms in the estrogen synthesis and metabolism pathways are associated with women's vasomotor symptom experiences during the menopausal transition. DESIGN: In 2002, a subset of women enrolled in the Seattle Midlife Women's Health Study since 1990 (N = 174) provided a buccal smear for genotyping. Women were recruited by complete ascertainment of selected multiethnic neighborhoods in 1990. Participants were midlife women with a mean age of 53 years in 2005, well educated, employed, married, and represented a multiethnic population. Genotyping was done for the following polymorphisms: CYP1A1m2; CYP1B1*2 and CYP1B1*3; CYP17 5'UTR; CYP19 3'UTR; CYP19 (TTTA)n; including CYP19 7r and CYP19 7(r-3); CYP19 8r and CYP19 11r; and ESR1PvuII and ESR1XbaI. Women rated their vasomotor symptom severity in diaries on days 5, 6, and 7 of the menstrual cycle or on a constant date each month for women skipping periods. Menopausal transition stage was determined from daily menstrual calendars. First voided urine specimens provided several times each year were assayed for estrone glucuronide. RESULTS: Women with the CYP19 11r polymorphism reported more severe and frequent hot flashes during the middle and late menopausal transition stages and postmenopause and higher E1G levels during middle and late stages. None of the other polymorphisms studied were related to hot flashes or to estrone glucuronide levels. CONCLUSIONS: These findings suggest a possible role for CYP19 polymorphisms in estrogen levels and in vasomotor symptoms during the menopausal transition that warrants further study in larger and more diverse populations of women.

Association of CYP17, CYP19, CYP1B1, and COMT polymorphisms with serum and urinary sex hormone concentrations in postmenopausal women.

Women with high circulating estrogen concentrations have an increased risk of breast cancer; thus, it is important to understand factors, including genetic variability, that influence estrogen concentrations. Several genetic polymorphisms that may influence sex hormone concentrations have been identified, including CYP17 (5'-untranslated region T-->C), CYP19 [intron 4 (TTTA)(n = 7-13) and a 3-bp deletion (-3)], CYP1B1 (Val(432)Leu), and COMT (Val(108/158)Met). We examined associations between these polymorphisms and serum concentrations of estrogens, androgens, and sex hormone-binding globulin and urinary concentrations of 2- and 16alpha-hydroxyestrone in 171 postmenopausal women, using data from the prerandomization visit of an exercise clinical trial. Participants were sedentary, not taking hormone therapy, and had a body mass index >24.0. Compared with noncarriers, women carrying two CYP19 7r(-3) alleles had 26% lower estrone (P < 0.001), 19% lower estradiol (P = 0.01), 23% lower free estradiol (P = 0.01), and 22% higher sex hormone-binding globulin concentrations (P = 0.06). Compared with noncarriers, women carrying at least one CYP19 8r allele had 20% higher estrone (P = 0.003), 18% higher estradiol (P = 0.02), and 21% higher free estradiol concentrations (P = 0.01). Women with the COMT Met/Met genotype had 28% higher 2-hydroxyestrone (P = 0.08) and 31% higher 16alpha-hydroxyestrone concentrations (P = 0.02), compared with Val/Val women. Few associations were found for CYP17 and CYP1B1 or with serum androgen concentrations. This study provides further evidence that genetic variation may appreciably alter sex hormone concentrations in postmenopausal women not taking hormone therapy.

Glutathione S-transferase M1, T1, and P1 polymorphisms and survival among lung cancer patients.

Glutathione S-transferase (GST) enzymes detoxify therapeutic drugs and reactive oxidants, so GST polymorphisms may influence survival after diagnosis of cancer. We evaluated survival according to GST polymorphisms in a population-based series of lung cancer patients. The study subjects (n = 274) were men diagnosed with lung cancer from 1993 through 1996 who participated in a case control study and provided a blood sample for genotyping. The presence of the GSTM1 and GSTT1 genes were assayed by multiplex PCR. Genotype at the GSTP1 Ile(105)Val substitution was determined by PCR and oligonucleotide ligation assay. The study subjects were followed for vital status through 2000, and overall survival was evaluated in Kaplan-Meier survival functions and Cox proportional hazards models. Subjects with the GSTM1 null genotype had shorter survival; the proportion of GSTM1 null subjects surviving at 5 years was 0.20 [95% confidence interval (CI) 0.14-0.27], compared with 0.29 (95% CI 0.22-0.37) for GSTM1 present subjects. The relative risk of death associated with GSTM1 null genotype, adjusted for stage at diagnosis and histology, was 1.36, 95% CI 1.04-1.80. There was no association between GSTT1 or GSTP1 genotype and survival in the overall study population, nor in a subgroup of patients treated with chemotherapy (n = 130). For GSTM1, our results are consistent with a previous study, which also observed that the GSTM1-null genotype, which confers susceptibility to lung cancer, was associated with shorter survival. Future studies of lung cancer survival should take into account GSTM1 genotype as well as investigate underlying mechanisms.