Oxidative Stress and Genetic Variants of Xenobiotic-Metabolising Enzymes Associated with COPD Development and Severity in Serbian Adults

Figures & data

Table 1a. The main characteristics and biomarkers in all COPD patient groups, all control groups and in sex-related groups.

	All		Male		Female
	COPD (n = 71)	Control (n = 153)	COPD (n = 33)	Control (n = 85)	COPD (n = 38)	Control (n = 68)
Age, years	59 (42–69)^a	47 (30–60)	61 (46–71)^b,d	42 (29–60)^e	56 (39–68)^c	51 (32–62)
Smokers (%)	49.3	50.7	39.4	47.6	57.9	54.7
Non-smokers (%)	7.0^a	33.1	3.0^b	31.0	10.5^c	35.9
Former smokers (%)	43.7^a	16.2	57.6^b,d	21.4^e	31.6^c	9.4
Smoking history (Pack-year)	37 (10–115)^a	18 (2–45)	40 (10–120)^b,d	20 (1–45)	30 (10–53)^c	15 (3–45)
BMI (kg/m^2)	24 (17–39)	26 (21–34)	26 (17–41)	27 (22–34)	22 (17–38)	25 (20–35)
8-OxodG/creatinine (nmol/mmol)	2.36 (0.81–8.26)^a	1.06 (0.55–2.29)	2.60 (0.74–8.56)^b	0.94 (0.48–1.65)^e	2.28 (0.89–8.07)^c	1.25 (0.69–2.65)
Creatinine (μmol/L)	57.0 (40.0–88.6)^a	77.0 (60.4–100.3)	63.0 (36.6–96.1)^b,d	86.0 (71.0–102.7)^e	51.5 (40.0–78.5)^c	69.5 (57.4–81.0)
Erythrocytes (x10^12/L)	4.6 (3.5–6.2)^a	4.8 (4.1–5.4)	4.7 (3.5–6.5)^b	5.0 (4.4–5.5)^e	4.4 (3.4–6.1)	4.5 (4.1–5.0)
Leucocytes ( x10^9/L)	9.7 (5.8–20.8)^a	6.8 (4.5–9.8)	9.1 (5.5–23.9)^b	7.3 (4.8–9.8)	10.3 (6.3–20.3)^c	6.6 (4.4–10.2)
Haemoglobin (g/dL)	13.8 (10.6–16.1)^a	14.6 (12.4–16.4)	14.4 (9.2–16.3)^b	15.4 (13.3–16.6)^e	13.0 (10.8–16.0)	13.5 (11.9–14.8)
FEV1, %	45 (29–56)	—	44 (28–54)	—	46 (31–66)	—
FVC, %	75 (54–90)	—	75 (58–90)	—	77 (54–92)	—
FEV1/FVC ratio	0.48 (0.39–0.62)	—	0.45 (0.33–0.57)^d	—	0.59 (0.39–0.67)	—

Quantitative data were expressed as geometric mean (5th–95th percentiles), except smoking status (%). ^ain all population: difference between COPD and Control; ^bin male population: difference between COPD and Control; ^cin female population: difference between COPD and Control; ^din COPD population: difference between males and females; ^ein Control population: difference between males and females; 8-oxodG: 8-oxo-7,8-dihydro-2'-deoxyguanosine; FEV1, % = forced expiratory volume in one second, % of predicted value; FVC, % = forced vital capacity, % of predicted value.

Table 1b. The main characteristics and biomarkers in sex-related COPD and control groups according to smoking status.

	Male						Female
	Smokers		Former smokers		Non-smokers		Smokers		Former smokers		Non-smokers
	COPD(n = 13)	Control (n = 40)	COPD(n = 14)	Control (n = 18)	COPD (n = 6)	Control (n = 27)	COPD (n = 21)	Control (n = 35)	COPD (n = 12)	Control (n = 9)	COPD (n = 5)	Control (n = 24)
Age, years	61^f (56–63)	39^h(34–47)	61^b(52–66)	46 (40–52)	58 (51–63)	48 (41–57)	54 (49–61)	53 (38–57)	60^d(57–62)	49 (41–54)	52 (43–59)	51 (47-58)
BMI (kg/m^2)	26 (20–32)	26 (25–29)	26 (22–32)	26 (23–29)	25 (25–30)	27 (25–29)	24 (20–30)	25 (22–28)	21^d(20–22)	26 (25–27)	32 (22–33)	23 (21-27)
8-OxodG/creatinine (nmol/mmol)	2.6^a (1.1–3.7)	0.9^h(0.7–1.2)	3.5^b (1.9–5.4)	0.9^i (0.7–1.3)	1.8 (1.5–2.6)	1.0 (0.7–1.3)	2.1^c(1.6–3.7)	1.6 (1.0–1.9)	2.5^d(1.7–4.0)	1.2 (0.9–2.1)	1.9 (1.4–2.8)	1.2 (1.0-1.6)
Creatinine (μmol/L)	62.0^a (56.5–68.5)	79.0^h(75.2–89.5)	64.0^b (50.0–71.0)	87.0^i (79.7–94.2)	63.0 (54.5–80.5)	90.0^j (86.0–99.0)	53.0^c(47.0–62.5)	70.0 (64.2–74.7)	45.0^d(41.2–62.5)	70.5 (63.7–79.5)	56.0^e(52.5–57.5)	67.5 (62.0-75.7)
Erythrocytes (x10^12/L)	4.6 (4.2–5.1)	4.9^h(4.7–5.1)	4.8 (4.4–4.9)	5.0^i (4.7–5.3)	5.3 ^g (4.5–5.6)	5.1^j (4.8–5.2)	4.4 (4.1–4.7)	4.5 (4.3–4.8)	4.6 (4.2–4.9)	4.4 (4.3–4.6)	3.8^e(3.7–4.6)	4.4 (4.2-4.7)
Leucocytes (x10^9/L)	7.5 (6.4–11.8)	7.7 (6.5–9.0)	9.9^b(8.0–11.0)	7.4^i (6.4–8.5)	9.7 (8.7–18.9)	6.3 (5.7–7.8)	10.0^c(7.8–14.6)	7.2 (6.1–8.1)	8.6^d(7.9–13.9)	6.0 (4.5–7.2)	10.8^e(10.5–13.1)	6.4 (4.7-7.3)
Haemoglobin (g/dL)	13.7^a (12.6–15.5)	15.4^h(14.9–15.8)	14.4 (13.2–15.4)	15.3 (14.6–16.0)	15.5 ^g (14.2–16.0)	15.2^j (14.9–15.9)	13.9 (12.1–14.3)	13.7 (13.2–14.3)	12.9 (12.0–14.5)	13.2 (12.9–13.3)	11.8^d (10.8–12.1)	13.2 (12.6-13.8)
FEV1, %	45 (38–52)	—	36 (27–56)	—	50 (25–73)	—	53 (29–76)	—	35 (29–56)	—	40 (32–69)	—
FVC, %	69 (58–87)	—	80 (48–89)	—	89 (54–100)	—	80 (51–94)	—	72 (66–89)	—	79 (52–93)	—
FEV1/FVC ratio	47^f (38–55)	—	45 (28–59)	—	40 (37–54)	—	62^j(55–68)	—	44 (36–45)	—	61 (38–67)	—

^ain male smokers: difference between COPD and Control; ^bin male former smokers: difference between COPD and Control; ^cin female smokers: difference between COPD and Control; ^din female former smokers: difference between COPD and Control; ^ein female non-smokers: difference between COPD and Control; ^fin COPD smokers: difference between males and females; ^gin COPD non-smokers: difference between males and females; ^hin Control population of smokers: difference between males and females; ⁱin Control population of former smokers: difference between males and females; ^jin Control population of non-smokers: difference between males and females; ^kin COPD female group: difference between smokers and former smokers.

Figure 1. Mean levels of urinary 8-oxodG/creatinine (nmol/mmol): a. in COPD and control groups according to smoking status; b. in COPD and control groups according to body mass index (BMI); c. in COPD group according to COPD stages. ^*difference between COPD and control groups (p < 0.05); ^#differences between former smokers with COPD group and smokers with COPD/non-smokers with COPD groups (p < 0.05); and differences between COPD with BMI < 18 group and COPD with BMI 18–25 group; ^§differences between very severe COPD with pack-year>30 group and severe COPD with pack-year > 30 group.

Table 2. Distribution of genotypes (dominant model) and gene combination of Xenobiotic-metabolising enzymes (XMEs) in all COPD patients, all control groups and in populations related to smoking status (smokers, non-smokers and former smokers).

Genotype/gene combination	COPD				Control				P
	All (n = 71)	S (n = 35)	NS (n = 5)	FS (n = 31)	All (n = 153)	S (n = 78)	NS (n = 50)	FS (n = 25)	All^b	All ^a	S^a	NS ^a	FS ^a
GSTM1^*
plus	45	37	80	48	54	57	47	62	0.297	0.201	0.049 ^d	0.159	0.297
null	55	63	20	52	46	43	53	37
GSTT1^*
plus	73	77	100	64	73	71	73	75	0.295	0.995	0.477	0.186	0.404
null	27	23	0	36	27	29	27	25
mEX Tyr113His
Tyr113Tyr	39	37	60	39	51	53	55	42	0.649	0.107	0.113	0.834	0.824
113Tyr/113His and 113His/113His	61	63	40	61	49	47	45	58
H-W χ^2 (P) ^c	4.1 (0.13)				1.05 (0.59)
mEH His139Arg
His139His	68	66	80	68	71	67	73	71	0.646	0.651	0.922	0.751	0.557
139His/139Arg and 139Arg/139Arg	32	34	20	32	29	33	27	29
H-W χ^2 (P) ^c	0.76 (0.69)				1.00 (0.61)
mEH activity phenotype
^#low	44	40	20	52	39	36	37	46	—	0.715	0.374	0.295	0.389
Intermediate	41	49	80	25	42	41	45	42	0.585
High	15	11	0	23	19	23	18	12	0.507
GSTM1/GSTT1
^#GSTM1-/T1-	14	14	0	16	12	16	10	4	—	0.603	0.219	0.086	0.301
GSTM1+/T1+	32	29	80	29	39	44	31	42	0.333
GSTM1-/T1+ and GSTM1+/T1-	54	57	20	55	49	40	59	54	0.719

All: all investigated subjects; S: smokers; NS: non-smokers; FS: former smokers; ^*null is GSTM1 or GSTT1 gene deletion; plus is the presence of intact GSTM1 or GSTT1gene; ^#reference variable when tested difference between patient and control group adjusted to age and pack-year; ^adifference between patient and control group; ^bdifference between patient and control group adjusted to age and pack-year; ^ctesting Hardy–Weinberg equilibrium in all population; ^dOR (95%CI): 2.27 (1.00–5.19).

Figure 2. Distribution of GSTM1/GSTT1 genotype combinations (with at least one deletion and without deletion): a. in all COPD and control groups; b. in non-smokers with COPD and control groups; c. in smokers with COPD and control groups; d. in former smokers with COPD and control groups.

Table 3. Binary logistic regression model for predicting the COPD development in all investigated subjects and sex-related populations.

	All			Males			Females
Predictor	(S.E)	p	OR (95% CI)	(S.E.)	p	OR (95% CI)	(S.E)	p	OR (95% CI)
Age	0.18 (0.05)	<0.001	1.19 (1.1–1.3)	0.25 (0.07)	<0.001	1.29 (1.12–1.48)	—	—	—
Pack-year	0.04 (0.02)	0.04	1.04 (1.00–1.08)	—	—	—	0.08 (0.04)	0.02	1.09 (1.01–1.16)
8-OxodG/creatinine	1.36 (0.38)	<0.001	3.91 (1.83–8.34)	2.13 (0.67)	0.001	8.42 (2.26–31.28)	1.28 (0.53)	0.01	3.60 (1.37–9.45)
Leucocytes	0.57 (0.15)	<0.001	1.77 (1.33–2.37)	0.58 (0.19)	0.003	1.75 (1.21–2.62)	0.39 (0.15)	0.01	1.47 (1.10–1.98)
GSTM1/GSTT1 with deletion	1.782 (0.79)	0.02	5.94 (1.27–27.91)	—	—	—	3.17 (1.12)	0.01	23.67 (2.62–213.46)
Constant	−19.05 (4.02)	<0.001	—	−22.47 (5.31)	<0.001	—	−10.38 (2.66)	<0.001	—
Full model	χ2 (df 3, N = 183) = 131.4, p < 0.001			χ2 (df 3, N = 116) = 101.4, p < 0.001			χ2 (df4, N = 67) = 49.28, p < 0.001

β (S.E): regression coefficient β (standard error of β), OR (95% CI): odds ratio (95% confidence interval).

Figure 3. Combined effect of high oxidative stress (urinary 8-oxodG/creatinine > 3.5 nmol/mmol), heavy smoking (pack-year > 30) and mEH activity phenotype (L-low, I-intermediate and + H-high) on the pulmonary function assessed by: a. FEV1%; b. FVC%. * difference compared to the group of COPD patients with low mEH activity phenotype, high level of oxidative stress and heavy smoking habits (>3.5 + >30).