The Kinetics of Transforming Growth Factor beta1 mRNA Expression and Its Serum Concentration in Graft-Versus-Host Disease After Allogeneic Hemopoietic Stem Cell Transplantation for Myeloid Leukemias.

Graft-versus-host disease (GVHD) remains one of the major complication following allogeneic haematopoietic stem cell transplantation (alloHSCT). Recent data indicates that transforming growth factor beta1 (TGF-β1) may play a role in the development of GVH reaction.

The study included 40 adult patients who underwent allogeneic bone marrow transplantation for myeloid leukemias between 2001-2004. Twenty four patients were transplanted for acute myeloid leukemia in first complete remission and 16 patients for chronic myeloid leukemia in first chronic phase. 25 patients received stem cells from unrelated donor whereas the donor was sibling for the remaining 15 recipients. Conditioning regimen consisted of busulphan and cyclosphamide (BuCy) and ciclosporin (CyS) and methotrexate (Mtx) were administered for GVHD prophylaxis. In all cases, the expression of TGF-β1 mRNA by real-time quantitive polymerase chain reaction (RT-QPCR) using ABI PRISM^TM 7700 (Taqman) and TGF-β1 serum concentration by commercial ELISA were measured fourfold in the peritransplant period (on days: -10, 0, +30 and +100).

Acute GVHD (aGVHD) experienced 20 patients, in 4 patients the symptoms were classified as severe (grades III-IV). Chronic GVHD (cGVHD) occurred in 11 patients (in 4 as a diffuse form). A median TGF-β1 mRNA expression was 7088 copies/μg of total RNA at day -10 before transplant, dropped to 1907 copies/μg of total RNA after conditioning (p<0.005) and then significantly increased on days +30 (p<0.04) and +100 (p<0.003) when compared to the day of transplant (median: 3808 and 7531 copies/μg of total RNA, respectively). A median TGF-β1 serum concentration was 21411 pg/ml at day -10 before transplant, dropped to 8277 pg/ml at the day of transplant (p<0.000063), the low value (median: 12184 pg/ml) was still detected on day +30 (p<0.0026) in comparison to the pretransplant period. A median TGF-β1 serum concentration significantly increased on day +100 (median: 19509 pg/ml) when compared to the day of transplant and to the day +30 (p<0.0025 and p<0.0196, respectively). All patients demonstrated a prompt decrease in TGF-β1 mRNA expression and its serum concentration after conditioning. In patients with acute GVHD, TGF-β1 mRNA expression and its serum concentration remained low until day +30 after transplant if compared to the transplant day (p<0.03 and p<0.006, respectively). TGF-β1 mRNA expression and its serum concentration significantly increased on day +100 if compared to the transplant day (p<0.0009 and p<0.02, respectively) in patients who developed chronic GVHD.

We demonstrate the kinetics of TGF-β1 changes both on molecular and protein level in patients who underwent alloHSCT for myeloid leukemias. These results show that TGF-β1 is likely to be an additional regulator of donor engraftment, probably its low levels contributing to the development of acute GVHD, which may suggest that TGF-β1 exerts beneficial effects in the early post transplant period. In contrast, chronic GVHD symptoms seem to correlate significantly with high TGF-β1 levels, suggesting that TGF-β1 is likely to increase the risk of cGVHD by causing fibrosis of target organs, which remains in coherence with TGF-β1 profibrotic activity.

No relevant conflicts of interest to declare.