Background Thrombopoietin (TPO) is a liver produced protein that drives megakaryocyte maturation. TPO is the main of regulator platelet production but may also increase platelet reactivity. As both thrombocytopenia and thrombosis are frequent manifestations among Systemic Lupus Erythematosus (SLE) patients, we investigated the relationship between TPO and disease parameters.
Methods TPO levels were measured in SLE patients (n=98) with clinical and laboratory data collected at the same time point as sampling for TPO, inflammatory cytokines and auto antibodies detection. Patients with RA (n=100) and healthy controls (n=100) served as TPO comparators. Associations and correlations were evaluated using non parametric methods.
Results Mean TPO was significantly higher) in SLE (326pg/ml) compared with RA patients (96pg/ml) (p=0.04, but not significantly different (p=0.20) from healthy controls (185pg/ml). Among SLE patients, TPO did not correlate with platelet or antiphospholipid antibodies levels, while increased TPO was not association with thrombocytopenic episodes, thrombotic events or disease activity. TPO levels correlated with MIP1-alpha (Rs 0.56, p<0.001), IL6 (Rs 0.26, p=0.02) and IL4 (Rs 0.29, p=0.01), while inversely correlated to C4 (Rs - 0.23, p=0.04). MIP1alpha was found to be the strongest independent predictor of increased TPO levels.
Conclusions TPO is significantly increased in a quarter of SLE patients, but this is unrelated to the occurrence of thrombocytopenia or thrombosis. MIP1-alpha is the main factor driving higher TPO levels among SLE patients, possibly through its inhibitory effect on megakaryopoeisis.
Disclosure of Interest None declared