Crucial factors of the inflammatory microenvironment (IL-1β/TNF-α/TIMP-1) promote the maintenance of the malignant hemopoietic clone of myelofibrosis: an in vitro study

// Daria Sollazzo 1, * , Dorian Forte 1, * , Nicola Polverelli 1 , Marco Romano 1 , Margherita Perricone 1 , Lara Rossi 1 , Emanuela Ottaviani 1 , Simona Luatti 1 , Giovanni Martinelli 1 , Nicola Vianelli 1 , Michele Cavo 1 , Francesca Palandri 1, * , Lucia Catani 1, * 1 Department of Experimental, Diagnostic and Specialty Medicine, Institute of Hematology “L. e A. Seràgnoli”, University of Bologna, Bologna, Italy * These authors contributed equally to this work Correspondence to: Lucia Catani, email: lucia.catani@unibo.it Keywords: circulating CD34 + cells, myelofibrosis, inflammatory microenvironment, migration, survival Received: November 12, 2015      Accepted: May 20, 2016      Published: June 11, 2016 ABSTRACT Along with molecular abnormalities (mutations in JAK2 , Calreticulin ( CALR ) and MPL genes ), chronic inflammation is the major hallmark of Myelofibrosis (MF). Here, we investigated the in vitro effects of crucial factors of the inflammatory microenvironment (Interleukin (IL)-1β, Tumor Necrosis Factor (TNF)-α, Tissue Inhibitor of Metalloproteinases (TIMP)-1 and ATP) on the functional behaviour of MF-derived circulating CD34 + cells. We found that, regardless mutation status, IL-1β or TNF-α increases the survival of MF-derived CD34 + cells. In addition, along with stimulation of cell cycle progression to the S-phase, IL-1β or TNF-α ± TIMP-1 significantly stimulate(s) the in vitro clonogenic ability of CD34 + cells from JAK2 V617 mutated patients. Whereas in the JAK2 V617F mutated group, the addition of IL-1β or TNF-α + TIMP-1 decreased the erythroid compartment of the CALR mutated patients. Megakaryocyte progenitors were stimulated by IL-1β ( JAK2 V617F mutated patients only) and inhibited by TNF-α. IL-1β + TNF-α + C-X-C motif chemokine 12 (CXCL12) ± TIMP-1 highly stimulates the in vitro migration of MF-derived CD34+ cells. Interestingly, after migration toward IL-1β + TNF-α + CXCL12 ± TIMP-1, CD34 + cells from JAK2 V617F mutated patients show increased clonogenic ability. Here we demonstrate that the interplay of these inflammatory factors promotes and selects the circulating MF-derived CD34 + cells with higher proliferative activity, clonogenic potential and migration ability. Targeting these micro-environmental interactions may be a clinically relevant approach.