Introduction and Objectives Markers of immune activation and inflammation are raised in pulmonary arterial hypertension; the degree of elevation of levels of pro-inflammatory cytokines in idiopathic pulmonary arterial hypertension has recently been shown to predict long term survival (Soon et al, Circulation, 2010). Much less is known of the role of cytokines in disease monitoring. We assessed levels of serum cytokines in patients at initial assessment prior to commencement of targeted therapy for pulmonary hypertension, and when the patient returned to the hospital for follow-up. We also examined if changes in serum cytokines correlated with changes in 6-min walk test (6MWT).

Methods 19 patients with a diagnosis of Group I PAH or Group IV chronic thromboembolic pulmonary hypertension in a distribution inaccessible to surgery were included. Patients with inflammatory conditions other than an associated connective tissue disease or a musculoskeletal condition that would interfere with the 6MWT were excluded. 11 healthy volunteers acted as a control group. Serum levels of interleukin (IL) 1ß, 2, 4, 6, 8, 10, 12p70 and tumour necrosis factor α (TNFα) were measured using a multiplex analyser. A Wilcoxon matched pairs test was used to compare differences between baseline and follow-up samples.

Results Patient and control demographics are presented in the Abstract P3 table 1. Levels of IL 2,6,8,10 and TNFα were elevated in the patient group compared to controls. Average time to repeat patient sampling was 4.7±1.8 months. There were no significant differences between the levels of any cytokines between baseline and follow-up in the patients and no overall correlation existed between change in 6MWT and change in any cytokine. When patients who had improved their 6MWT on follow-up were analysed as a separate group, there was a significant (p=0.0068) drop in IL6 levels on follow-up.

Conclusions Several cytokines were elevated in these patients with pulmonary hypertension. The role of cytokines in disease monitoring requires further study and there seems to be little relation with serum cytokines, except IL6, and a change in a patient's clinical state as measured by 6MWT. Replication of results from this pilot study and examination of longitudinal trends in cytokine levels are warranted.