Association of genetic polymorphisms with mercapturic acids in the urine of young healthy subjects before and after exposure to outdoor air pollution

Figures & data

Figure 1. Workflow of the research. a total of 50 healthy subjects were recruited according to the enrollment criteria. Peripheral blood and urinary samples of all participants were collected at five different time points, including Point C, Po1, Pu1, Po2 and Pu2. Then, SNP genotyping detection of genomic DNA from peripheral blood at Point C was conducted by an SNP panel, and the expression levels of five mercapturic acids in urinary samples at five points were detected by SPE-LC-MS/MS. Finally, association analysis between SNPs and changes in five mercapturic acids was carried out to discover potential biomarkers for the early monitoring of air pollution as risk factors for lung cancer. Point C: the clean time point; Point Po1: the first polluted time point; Point Pu1: the first purified time point; Point Po2: the second polluted time point; Point Pu2: the second purified time point.

Table 1. General characteristics of 50 healthy participants.

Characteristics	Value and percentage
	Female	Male
Percentage of gender	48% (24)	52% (26)
Age at tested (years)	24.88 ± 0.83	24.77 ± 1.34
Height (cm)	161.71 ± 5.08	177.69 ± 4.82
Body Weight at tested (kg)	53.13 ± 5.84	71.92 ± 9.76
BMI at tested (kg/m2)	20.27 ± 1.63	22.73 ± 2.30
Smoking history (None)	24	26

BMI = Body mass index.

Table 2. Genotype of 47 pollution-relevant SNPs selected on the basis of their biological literature search.

SNP_ID	Gene	Homozygous genotype with wild-type allele		Heterozygous geneotype		Homozygous genotype with variant allele		Total number	Gene Describe
		genotype	Count	genotype	Count	genotype	Count
rs1001179	CAT	C	47	CT	3		0	50	catalase
rs1007991	SOD3	C	14	CG	30	G	6	50	superoxide dismutase 3, extracellular
rs1048943	CYP1A1	C	2	T	33	TC	15	50	cytochrome P450, family 1, subfamily A, polypeptide 1
rs1050450	GPX1	G	43	GA	7		0	50	glutathione peroxidase 1
rs10516526	GSTCD	A	50		0		0	50	glutathione S-transferase, C-terminal domain containing
rs10517	NQO1	A	8	AG	31	G	11	50	NAD(P)H dehydrogenase, quinone 1
rs1051740	EPHX1	C	4	CT	31	T	15	50	epoxide hydrolase 1, microsomal (xenobiotic)
rs1056836	CYP1B1	G	32	GC	18		0	50	cytochrome P450, family 1, subfamily B, polypeptide 1
rs10759931	N/A	A	14	G	8	GA	28	50	NA
rs10759932	TLR4	C	5	T	23	TC	22	50	toll-like receptor 4
rs1138272	GSTP1	C	49	TC	1		0	50	glutathione S-transferase pi 1
rs1695	GSTP1	A	32	AG	14	G	4	50	glutathione S-transferase pi 1
rs1799895	SOD3	C	48	CG	2		0	50	superoxide dismutase 3, extracellular
rs1800440	CYP1B1	T	50		0		0	50	cytochrome P450, family 1, subfamily B, polypeptide 1
rs1800566	NQO1	A	6	G	19	GA	25	50	NAD(P)H dehydrogenase, quinone 1
rs1800629	TNF	G	45	GA	5		0	50	tumor necrosis factor
rs1871042	GSTP1	C	34	CT	13	T	3	50	glutathione S-transferase pi 1
rs1898830	TLR2	A	18	G	9	GA	23	50	toll-like receptor 2
rs1927911	TLR4	A	7	AG	29	G	14	50	toll-like receptor 4
rs2234922	EPHX1	A	40	G	1	GA	9	50	epoxide hydrolase 1, microsomal (xenobiotic)
rs2266637	GSTT1	C	36	T	2	Deletion	12	50	glutathione S-transferase theta 1
rs2333227	MPO	TC	50		0		0	50	myeloperoxidase
rs2395185	N/A	G	25	GT	22	T	3	50	NA
rs2536512	SOD3	A	6	G	15	GA	29	50	superoxide dismutase 3, extracellular
rs2695231	SOD3	T	3	TC	47		0	50	superoxide dismutase 3, extracellular
rs2736100	TERT	A	17	C	15	CA	18	50	telomerase reverse transcriptase
rs2737190	N/A	A	14	G	7	GA	29	50	NA
rs2855262	SOD3	C	5	T	13	TC	32	50	superoxide dismutase 3, extracellular
rs2917666	N/A	G	1	CG	13	C	36	50	NA
rs4488809	TP63	C	14	T	13	TC	23	50	tumor protein p63
rs4600802	TP63	C	8	T	21	TC	21	50	tumor protein p63
rs4646424	N/A	A	50		0		0	50	NA
rs4673	CYBA	A	0	AG	5	G	45	50	cytochrome b-245, alpha polypeptide
rs4696480	TLR2	A	18	T	9	TA	23	50	toll-like receptor 2
rs4880	SOD2	A	40	AG	8	G	2	50	superoxide dismutase 2, mitochondrial
rs4891	GSTP1	C	4	T	32	TC	14	50	glutathione S-transferase pi 1
rs596603	N/A	G	24	GT	18	T	8	50	NA
rs699473	SOD3	C	14	T	2	TC	34	50	superoxide dismutase 3, extracellular
rs7086803	VTI1A	A	2	AG	16	G	32	50	vesicle transport through interaction with t-SNAREs 1A
rs749174	GSTP1	A	3	AG	13	G	34	50	glutathione S-transferase pi 1
rs762803	GSTP1	A	3	C	34	CA	13	50	glutathione S-transferase pi 1
rs769214	CAT	A	3	G	32	GA	15	50	catalase
rs8192287	SOD3	G	44	GT	6		0	50	superoxide dismutase 3, extracellular
rs8192288	SOD3	G	43	GT	7		0	50	superoxide dismutase 3, extracellular
rs8192291	SOD3	C	37	T	8	TC	5	50	superoxide dismutase 3, extracellular
rs9387478	DCBLD1	A	15	C	14	CA	21	50	discoidin, CUB and LCCL domain containing 1
rs9932581	CYBA	C	11	T	14	TC	25	50	cytochrome b-245, alpha polypeptide

Figure 2. Expression levels of five mercapturic acids in urinary samples at five different time points. Expression abundance represented the value after taking the average expression of mercapturic acids in 50 samples and normalizing by Z-score. CEMA: N-acetyl-S-(2-cyanoethyl)-cysteine; HMPMA: 3-hydroxy-1-methylpropylmercapturic acid; SPMA: N-acetyl-S-phenyl-L-cysteine; HPMA: N-acetyl-S-(3-hydroxypropyl)-l-cysteine; HEMA: N-acetyl-S-(2-hydroxyethyl)-L-cysteine.

Table 3. A total of 21 SNPs mapped to 9 genes had significant relationships with changes in expression levels of five mercapturic acids (P < .05).

Metabolites	SNP	Gene Symbol	Chr	Position	Variety of metabolite change	R value	Pvalue	Gene Description
CEMA	rs10759931	N/A	9	117701869	log2(Po1/C)	.288	.043
	rs2695231	SOD3	4	24796559	log2(Po1/C)	.366	.009	superoxide dismutase 3, extracellular
	rs2395185	N/A	6	32465390	log2(Pu1/Po1)	.296	.037
	rs2266637	GSTT1	22	24376845	log2(Pu1/Po1)	−.310	.029	glutathione S-transferase theta 1
	rs4488809	TP63	3	189638472	log2(Pu1/Po1)	.507	.000	tumor protein p63
	rs4600802	TP63	3	189665641	log2(Pu1/Po1)	−.459	.001	tumor protein p63
HMPMA	rs1898830	TLR2	4	153687301	log2(Po1/C)	−.288	.043	toll-like receptor 2
SPMA	rs10759931	N/A	9	117701869	log2(Pu1/Po1)	.426	.002
	rs2737190	N/A	9	117701903	log2(Pu1/Po1)	.368	.008
	rs596603	N/A	11	67592132	log2(Pu1/Po1)	−.295	.037
	rs4673	CYBA	16	88646828	log2(Po1/C)	−.291	.040	cytochrome b-245, alpha polypeptide
	rs769214	CAT	11	34438170	log2(Po1/C)	.325	.021	catalase
	rs10759932	TLR4	9	117702866	log2(Pu1/Po1)	−.424	.002	toll-like receptor 4
	rs1927911	TLR4	9	117707776	log2(Pu1/Po1)	.368	.008	toll-like receptor 4
	rs1695	GSTP1	11	67585218	log2(Pu1/Po1)	−.323	.022	glutathione S-transferase pi 1
	rs1871042	GSTP1	11	67586373	log2(Pu1/Po1)	−.376	.007	glutathione S-transferase pi 1
	rs4891	GSTP1	11	67,586,499	log2(Pu1/Po1)	−.323	.022	glutathione S-transferase pi 1
	rs749174	GSTP1	11	67585782	log2(Pu1/Po1)	.376	.007	glutathione S-transferase pi 1
	rs762803	GSTP1	11	67584785	log2(Pu1/Po1)	−.376	.007	glutathione S-transferase pi 1
HPMA	rs10759931	N/A	9	117701869	log2(Po1/C)	.291	.041
	rs2737190	N/A	9	117701903	log2(Po1/C)	.338	.016
	rs1927911	TLR4	9	117707776	log2(Po1/C)	.338	.016	toll-like receptor 4
	rs2695231	SOD3	4	24796559	log2(Po1/C)	.299	.035	superoxide dismutase 3, extracellular
	rs8192287	SOD3	4	24794946	log2(Po1/C)	.285	.045	superoxide dismutase 3, extracellular
	rs699473	SOD3	4	24795181	log2(Pu1/Po1)	−.286	.044	superoxide dismutase 3, extracellular
HEMA	rs2737190	N/A	9	117,701,903	log2(Pu1/Po1)	.289	.042
	rs2234922	EPHX1	1	225838705	log2(Po1/C)	.336	.017	epoxide hydrolase 1, microsomal (xenobiotic)
	rs10759932	TLR4	9	117702866	log2(Pu1/Po1)	−.295	.037	toll-like receptor 4
	rs1927911	TLR4	9	117707776	log2(Pu1/Po1)	.289	.042	toll-like receptor 4

Figure 3. The top-ranked (P ≤.05) KEGG pathways for 9 genes corresponding to 21 SNPs had significant relationships with changes in the expression levels of five mercapturic acids. *P <.05, ** P <.01.

Data availability statement

All the datasets in the current study are available from the corresponding author upon reasonable request.