Figures
- Figure 1–
a) C-reactive protein (CRP) concentration, b) interleukin (IL)-6 concentration and c) leptin concentration in nonobese and obese subjects with and without asthma. Horizontal bars represent median concentrations. #: p<0.0001; ¶: p=0.008; +: p=0.003; §: p=0.013; ƒ: p=0.001.
- Figure 2–
a) Sputum neutrophil percentages and b) sputum eosinophil percentages in nonobese and obese subjects with and without asthma. Horizontal bars represent a) mean and b) median concentrations. #: p=0.005; ¶: p=0.001; +: p=0.003; §: p<0.0001; ƒ: p=0.007.
- Figure 3–
Increased proportion of neutrophilic asthma (sputum neutrophils ≥61%) in obese females with asthma. #: p=0.017 versus nonobese asthmatic females.
Tables
- Table 1– Subject characteristics
Nonobese asthma Obese asthma Nonobese controls Obese controls p-value Subjects n 68 47 63 16 Age yrs 56.7 (39.0–64.5) 59.0 (52.1–64.6) 58.7 (27.9–66.4) 57.3 (34.7–65.0) 0.671 Females % 64.7 61.7 63.5 56.3 0.933 FEV1 % pred 82.0 (67.5–92.5)+,§ 84.0 (67.0–95.0)+ 101.0 (94.0–115.0) 99.0 (82.0–111.0) <0.001 FVC % pred 96.4±17.8+ 92.8±15.8+,§ 109.1±12.6 104.4±17.3 <0.001 FEV1/FVC 68.5 (61.5–74.5)+,§ 72.0 (64.0–80.0)+ 78.0 (75.0–82.0) 76.0 (74.0–78.5) <0.001 Atopy % 73.5+,§ 66.0+,§ 41.3 25.0 <0.001 BMI kg·m−2 26.1 (23.8–28.3)§ 34.7 (33.2–39.9)+,ƒ 25.8 (23.4–28.0)§ 33.0 (31.0–35.0) <0.001 ICS dose# μg·day−1 500 (0–1000) 1000 (0–2000)ƒ NA NA 0.003 ICS use % 58.8 70.2 NA NA 0.212 ACQ Score 0.7 (0.4–1.3) 0.9 (0.4–1.6) NA NA 0.811 GINA classification % 0.708 Intermittent 32.4 40.4 NA NA Mild persistent 13.2 8.5 NA NA Moderate persistent 39.7 34.0 NA NA Severe persistent 14.7 17.0 NA NA LogPD15¶ mL 1.81 (-0.35–2.16) 1.91 (1.53–2.51) NA NA 0.104 Data are presented as median (interquartile range) or mean±sd, unless otherwise stated. FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; BMI: body mass index; ICS: inhaled corticosteroid; ACQ: Asthma Control Questionnaire; GINA: Global Initiative for Asthma; PD15: provocation dose of 4.5% hypertonic saline required to induce a drop in FEV1 of 15% from baseline; NA: not available. #: beclomethasone equivalents; ¶: presented as geometric median (interquartile range); +: p<0.01 versus nonobese controls; §: p<0.02 versus obese controls; ƒ: p<0.01 versus nonobese asthma.
- Table 2– Plasma C-reactive protein (CRP), interleukin (IL)-6 and leptin, and sputum inflammatory markers classified by subject group
Nonobese asthma Obese asthma Nonobese controls Obese controls p-value Obesity × asthma interaction Obese versus nonobese Asthma versus controls Subjects n 59 42 54 11 CRP mg·L−1 1.6 (0.9–5.2) 8.2 (2.9–13.0) 1.6 (0.7–3.6) 2.2 (1.6–5.5) 0.003 IL-6 pg·mL−1 1.3 (0.9–1.9) 2.4 (1.6–3.3) 1.0 (0.8–1.3) 1.6 (1.2–2.1) 0.626 0.496 0.044 Leptin pg·mL−1 3539 (2187–8342) 8637 (5906–11199) 3864 (2361–6835) 5655 (1779–10602) 0.290 <0.001 0.454 Total cell count 106 cells·mL−1 3.1 (2.3–4.8) 2.3 (1.4–4.2) 2.7 (1.9–4.3) 3.0 (1.5–7.8) 0.203 0.566 0.348 Neutrophils % 37.8±21.9 50.8±23.0 36.1±23.8 24.6±21.2 0.012 Neutrophils 106 cells·mL−1 1116 (539–2526) 1271 (347–2862) 797 (248–1890) 358 (216–3360) 0.815 0.464 0.506 Eosinophils % 1.3 (0.5–5.3) 1.4 (0.3–3.0) 0.3 (0–1.3) 0.3 (0.3–1.8) 0.119 0.157 0.001 Eosinophils 106 cells·mL−1 51 (15–170) 33 (2–80) 9 (0–38) 20 (6–43) 0.102 0.111 0.013 Macrophages % 50.6±23.7 41.5±22.1 58.1±22.7 68.7±20.7 0.050 0.089 0.110 Macrophages 106 cells·mL−1 1535 (967–2251) 826 (358–1508) 1507 (689–2545) 1862 (1113–4410) 0.032 Lymphocytes % 0.5 (0–1.3) 0.3 (0–1.0) 1.4 (0.5–2.3) 1.3 (0–2.3) 0.990 0.741 0.056 Lymphocytes 106 cells·mL−1 17.8 (2.3–38.3) 2.3 (0–22.3) 29.3 (7.4–67.7) 40.6 (0–147.2) 0.245 0.159 0.319 Squamous cells % 1.7 (0.5–4.5) 3.6 (0.7–8.1) 5.0 (2.4–9.9) 2.0 (1.5–5.6) 0.012 Squamous cells 106 cells·mL−1 54.1 (17.9–167.5) 79.5 (21.8–121.7) 145.0 (85.4–261.3) 87.3 (35.1–275.1) 0.556 0.561 0.024 Data are presented as median (interquartile range) or mean±sd, unless otherwise stated. p-values are given for the interaction and main effects of asthma and obesity.
- Table 3– Multiple linear regression model describing predictors of sputum neutrophil percentages in all subjects with asthma
Unadjusted model Final model (R2=0.108, p=0.004) β-coefficient (95% CI) p-value β-coefficient (95% CI) p-value Age yrs 0.395 (0.085–0.704) 0.013 0.330 (0.022–0.639) 0.036 Sex 0.108 (-9.486–9.702) 0.982 BMI kg·m−2 0.937 (0.238–1.635) 0.009 0.801 (0.102–1.499) 0.025 Total SFA mg·L−1 0.017 (-0.002–0.036) 0.075 Total MUFA mg·L−1 0.016 (-0.001–−0.032) 0.062 Total PUFA mg·L−1 0.003 (-0.014–0.019) 0.760 ICS dose# μg·day−1 0.003 (-0.002–0.009) 0.235 Use of ICS treatment yes/no 4.831 (-4.515–14.177) 0.308 BMI: body mass index; SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; ICS: inhaled corticosteroid. #: beclomethasone equivalents.
- Table 4– Multiple linear regression model describing predictors of sputum neutrophil percentages in females with asthma
Unadjusted model Final model (R2=0.102, p=0.009) β-coefficient (95% CI) p-value β-coefficient (95% CI) p-value Age yrs 0.419 (0.025–0.814) 0.037 BMI kg·m−2 1.015 (0.258–1.772) 0.009 1.015 (0.258–1.772) 0.009 Total SFA mg·L−1 0.003 (-0.023–0.028) 0.840 Total MUFA mg·L−1 0.013 (-0.010–0.035) 0.261 Total PUFA mg·L−1 -0.008 (-0.029–0.013) 0.456 ICS dose# μg·day−1 0.004 (-0.002–0.011) 0.173 Use of ICS treatment yes/no 8.508 (-3.147–20.163) 0.150 BMI: body mass index; SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; ICS: inhaled corticosteroid. #: beclomethasone equivalents.
- Table 5– Multiple linear regression model describing predictors of sputum neutrophil percentages in males with asthma
Unadjusted model Final model (R2=0.286, p=0.005) β-coefficient (95% CI) p-value β-coefficient (95% CI) p-value Age yrs 0.423 (-0.158–1.003) 0.148 BMI kg·m−2 0.594 (-1.208–2.397) 0.507 Total SFA mg·L−1 0.036 (0.008–0.065) 0.014 0.108 (0.036–0.180) 0.004 Total MUFA mg·L−1 0.020 (-0.007–0.046) 0.135 -0.068 (-0.131–−0.005) 0.035 Total PUFA mg·L−1 0.019 (-0.008–0.047) 0.165 ICS dose# μg·day−1 0.000 (-0.012–0.012) 0.962 Use of ICS treatment yes/no −1.339 (-17.900–15.222) 0.870 BMI: body mass index; SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids; ICS: inhaled corticosteroid. #: beclomethasone equivalents.
- Table 6– Total and percentage plasma fatty acids (FAs) in nonobese and obese subjects with asthma, by sex
Nonobese asthmatic females Nonobese asthmatic males Obese asthmatic females Obese asthmatic males p-value Total FAs mg·L−1 3316 (2795–3898) 2966 (2612–3335) 3232 (2924–3586) 3385 (3034–4400) 0.150 % SFA 28.6±1.7# 28.6±1.7# 28.8±1.4# 30.4±2.4 0.005 % MUFA 23.9±3.6#,*** 25.2±2.8# 26.3±2.7# 29.2±3.1 <0.001 % PUFA 47.5±4.6# 46.3±3.5# 44.9±3.2# 40.4±4.7 <0.001 Data are presented as median (interquartile range) or mean±sd, udless otherwise stated. SFA: saturated fatty acids; MUFA: monounsaturated fatty acids; PUFA: polyunsaturated fatty acids. #: p<0.02 versus obese asthmatic males; ***: p<0.001 versus obese asthmatic females.
