Fibroproliferative activity in patients with immune thrombocytopenia (ITP) treated with thrombopoietic agents
Hepatocyte Growth Factor
Purpura, Thrombocytopenic, Idiopathic
Recombinant Fusion Proteins
This study assessed the grade of bone marrow (BM) fibrosis and its association with a seromarker for collagen-III formation and fibrosis-related cytokines in 25 immune thrombocytopenia (ITP) patients treated with thrombopoietin receptor agonists (Tpo-RA) who had at least one BM biopsy. Assessment of 8 pre- and on-treatment BM biopsies revealed statistically significant increases in reticulin. Reticulin in biopsies performed after a median of 1·4 years of treatment was graded: MF-0 in 3 (12%), MF-1 in 19 (76%), MF-2 in 2 (8%) and MF-3 in 1 (4%). No cytogenetic or flow-cytometric abnormalities were detected. Median pretreatment Procollagen III N-propeptide (PIIINP) (6·6 μg/l) was significantly higher than on-treatment levels (5·6 μg/l); both were higher than controls (3·4 μg/l; P < 0·001). PIIINP was negatively correlated with treatment duration (r = -0·49) suggesting a decelerated reticulin production over time. There was a trend towards an association between grade of reticulin and PIIINP. Transforming growth factor (GF)-beta and basic-Fibroblast GF were not different between patients and controls but Hepatocyte GF (HGF), an anti-fibrotic cytokine, was significantly elevated in patients. In conclusion, low-grade BM reticulin fibrosis is seen in most ITP patients on Tpo-RA. The novel findings of decreasing PIIINP and elevated HGF need further investigation to explore their significance in BM fibrogenesis.