FRI0470 CARDIORESPIRATORY FITNESS IN JUVENILE IDIOPATHIC ARTHRITIS IN 6 – 17-YEAR-OLD CHILDREN- CROSS-SECTIONAL STUDY

Background:

Children with juvenile idiopathic arthritis (JIA) have been found to have reduced cardiorespiratory fitness and lower physical activity. Poor cardiorespiratory fitness is associated with a risk of cardiometabolic diseases.

Objectives:

The aim of this study was to study the levels of cardiorespiratory fitness, respiratory function and hemodynamic responses during and after maximal cycle ergometer exercise test in children with JIA aged 6-17 years and compare the results with healthy controls.

Methods:

Study group in this analysis consisted of 43 patients with JIA who were treated in Department of Pediatrics in Kuopio University Hospital, Finland and 40 healthy age- and sex matched controls. Maximal exercise tests were carried out with an electromagnetic cycle ergometer using a pediatric saddle module. Maximal workload per kilogram (Wmax/kg) was used as a measure of cardiorespiratory fitness and was presented relative to bodyweight. In addition the peak values of VO2per kilogram (VO2max/kg) were used as a measure of highest amount of oxygen that an individual can consume during exercise. Values of VO2maxwere collected from respiratory gases measured directly from breath by breath method and was presented relative to body weight.

Physical activity and sedentary behavior (minutes per day) was assessed by the PANIC (Physical activity and nutrition in children -study) Physical Activity Questionnaire which the participants filled.

Results:

Statistical analyses were performed for 43 children with JIA and 40 controls. Mean age in JIA group was 12.09 years (95%Cl 11.04-13.14), and 11.72 years (95%CI 10.52-12.93) in controls (p=0.572). Mean body mass index for age (BMI) was 22.58 kg/m2(95%CI 21.54-23.62) in JIA and 18.95 kg/m2(95%CI 17.73-20.16) in controls (p<0.05). In JIA group BMI was 19.18 % higher compared to controls. Mean physical activity in JIA group was 94.11 minutes per day (95% Cl 81.09-107.13), and 122.54 minutes per day (95% CI 102.84-142.24) in controls, thus JIA group was 23.20 % less physically active than controls (p=0.015).

Mean Wmax/kg was 2.65 W/kg (95% CI 2.49-2.82) in JIA and 3.01 W/kg (95%CI 2.86-3.15) in controls thus Wmax/kg in JIA was 0.36 W/kg (11.8 %) lower than in controls, (p = 0.002). VO2max/kg was 37.00 (95%CI 33.96-40.84) ml/kg/min in JIA and 43.30 (95%CI 40.79-45.82) ml/kg/min in controls thus in JIA group mean VO2max/kg was 6.3 ml/kg/min (14.4 %) lower than in controls (p=0.001).

Conclusion:

Children with JIA were found to have significantly lower cardiorespiratory fitness. In addition, BMI in JIA patients was higher compared to healthy age- and sex-matched controls. Impaired cardiorespiratory fitness and higher BMI may predispose children with JIA to cardiometabolic comorbidities later in life. In addition to disease-control, more attention should be paid to maintaining good cardiorespiratory fitness and normal BMI in these patients already before adulthood.

References:

[1]M Nørgaard, M Twilt, LB Andersen & T Herlin (2016) Accelerometry-based monitoring of daily physical activity in children with juvenile idiopathic arthritis, Scandinavian Journal of Rheumatology, 45:3, 179-187,

[2]Maggio, A.B.R., Hofer, M.F., Martin, X.E. et al. Reduced physical activity level and cardiorespiratory fitness in children with chronic diseases. Eur J Pediatr 169, 1187–1193 (2010)

[3]Bohr, AH., Fuhlbrigge, R.C., Pedersen, F.K. et al. Premature subclinical atherosclerosis in children and young adults with juvenile idiopathic arthritis. A review considering preventive measures. Pediatr Rheumatol (2016)14: 3.

Acknowledgments:

Panu Karjalainen1, Timo Pitkänen1, Anneli Paloranta2, Kirsi Saastamoinen1

1University of Eastern Finland 2 Kuopio university hospital, Finland

Disclosure of Interests:

None declared

Effect of fuel zinc content on toxicological responses of particulate matter from pellet combustion in vitro

Significant amounts of transition metals such as zinc, cadmium and copper can become enriched in the fine particle fraction during biomass combustion with Zn being one of the most abundant transition metals in wood combustion. These metals may have an important role in the toxicological properties of particulate matter (PM). Indeed, many epidemiological studies have found associations between mortality and PM Zn content. The role of Zn toxicity on combustion PM was investigated. Pellets enriched with 170, 480 and 2300 mg Zn/kg of fuel were manufactured. Emission samples were generated using a pellet boiler and the four types of PM samples; native, Zn-low, Zn-medium and Zn-high were collected with an impactor from diluted flue gas. The RAW 264.7 macrophage cell line was exposed for 24h to different doses (15, 50,150 and 300 μg ml(-1)) of the emission samples to investigate their ability to cause cytotoxicity, to generate reactive oxygen species (ROS), to altering the cell cycle and to trigger genotoxicity as well as to promote inflammation. Zn enriched pellets combusted in a pellet boiler produced emission PM containing ZnO. Even the Zn-low sample caused extensive cell cycle arrest and there was massive cell death of RAW 264.7 macrophages at the two highest PM doses. Moreover, only the Zn-enriched emission samples induced a dose dependent ROS response in the exposed cells. Inflammatory responses were at a low level but macrophage inflammatory protein 2 reached a statistically significant level after exposure of RAW 264.7 macrophages to ZnO containing emission particles. ZnO content of the samples was associated with significant toxicity in almost all measured endpoints. Thus, ZnO may be a key component producing toxicological responses in the PM emissions from efficient wood combustion. Zn as well as the other transition metals, may contribute a significant amount to the ROS responses evoked by ambient PM.