Outcomes of global coagulation assays in patients with Philadelphia-negative myeloproliferative neoplasms with respect to genetic determinants of clonal progression

Classical myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders that manifest with inflammation, promotion of atherosclerosis, hypercoagulability, fibrosis, and clonal evolution. The complex biological background lends itself to multi-omics studies. We have previously shown that reduced platelet fibrinogen receptor (PFR) expression may follow hyperactivation of plasma-dependent mechanisms, such as tissue factor (TF) release, unbalanced thrombin generation, involvement of protease-activated receptors (PARs). Acetylsalicylic acid (ASA) helped to restore the expression of PFRs. In this study, we enrolled 53 MPN patients, subjecting them to advanced genetic testing (panel of 30 genes in NGS), global coagulation testing (Rotational Thromboelastometry - ROTEM) and cytofluorometric determination of PFRs. ROTEM parameters appear to differ considerably depending on the type of pathology under investigation, cell count, and selected mutations. Essential thrombocythemia (ET) and CALR mutation appear to correlate with increased efficiency of both classical coagulation pathways, with significantly more contracted clot formation times (CFTs). In contrast, primary myelofibrosis (PMF) and polycythemia vera (PV) show greater imbalances in the hemostatic system. PV, probably due to its peculiar hematological features, shows a lengthening of the CFT and, at the same time, a selective contraction of parameters in INTEM with the increase of platelets and white blood cells. PMF - in contrast - seems to exploit the extrinsic pathway more to increase cell numbers. The presence of DNMT3A mutations is associated with reduced clotting time (CT) in EXTEM, while ASXL1 causes reduced maximal lysis (ML). EZH2 could be responsible for the elongation of CFT in INTEM assay. In addition, increased PFR expression is associated with history of hemorrhage and sustained CT time in FIBTEM under ASA prophylaxis. Our findings corroborate the existing models on the connection between fibrosis, genetic complexity, clonal progression, and hypercoagulability. Global coagulation assays and PFR expression are potentially useful tools for dynamic evaluation of treatments’ outcomes.

L'elastometria Shear-wave epato-splenica nella diagnosi e stadiazione delle malattie mieloproliferative Ph-negative e della mielofibrosi

Introduzione: La stiffness epato-splenica, misurata attraverso la transient elastography (TE), è stata associata con la fibrosi midollare nei pazienti con malattia mieloproliferativa (MPNs). La rigidità dei tessuti può essere valutata con la shear-wave elastography (SWE), con due tecniche: point (pSWE) e bidimensionale (2DSWE). Obiettivi dello studio sono: 1) identificare le differenze di TE fra i pazienti con MPNs, i cirrotici e volontari sani (HV); 2) valutare specifiche caratteristiche di TE in pazienti con MF, PV ed ET; 3) stabilire una correlazione con il grado di fibrosi midollare. Metodi: in questo studio monocentrico, MPN, cirrotici ed HV hanno eseguito elastometria epato-splenica con pSWE e 2DSWE. Risultati: 236 pazienti sono stati inclusi in questo studio: 64 con MF (27.1%), 33 con PV (14%), 46 con ET (19.4%), 75 HV (32%) e 18 (8%) cirrotici. Al confronto con gli HV, i pazienti con MF hanno maggiore stiffness splenica (pSWE 40.9 vs 26.3 kPa, p<0.001; 2DSWE 34.9 vs 20.1 kPa, p<0.001) ed epatica (pSWE 7.72 vs 5.52 kPa, p<0.001; 2DSWE 6.96 vs 5.01 kPa, p<0.001). Al confronto con i pazienti con PV ed ET, quelli con MF hanno maggiori valori di stiffness epatici (p<0.001) e splenici (p<0.001). In fibrosi di basso (0-1) (n=81 , 60.4%) vs alto grado (2-3) (n=42, 39.6%), sono evidenti valori di stiffness maggiori nei pazienti con fibrosi di alto grado sia per il fegato (pSWE 5.2 vs 6.65 kPa; 2DSWE 5.1 vs 6.05 kPa) che nella milza (pSWE 27.2 vs 37.9 kPa, 2DSWE 21.7 vs 30.75 kPa – p<0.001) Conclusioni: La TE distingue i pazienti con MF sia dai sani che dalle altre MPNs. Valori di TE sono significativamente associati con caratteristiche rilevanti che includono la fibrosi midollare in tutte le MPNs. I valori di stiffness epatici e splenici sono pertanto rilevanti nella diagnosi e management delle MPNs.

Policitemia Vera: scoperta di saggi di biopsia liquida finalizzata a identificare i biomarcatori correlati al rischio trombotico

La Policitemia Vera (PV) è una neoplasia mieloproliferativa con un aumentato rischio di trombosi e di progressione verso la Mielofibrosi. L'infiammazione cronica è comunemente osservata nelle neoplasie mieloproliferative, compresa la PV. La rete infiammatoria, tra le varie componenti, comprende le vescicole extracellulari (EVs), che svolgono un ruolo nella comunicazione cellula-cellula. Inoltre, le componenti microbiche circolanti sono state recentemente indicate come potenziali modificatori dell'infiammazione, della coagulazione e dell’emopoiesi in generale. Qui abbiamo studiato il DNA microbico delle EVs circolanti attraverso. Sangue periferico e feci sono stati raccolti da pazienti con PV (n=38) e da donatori sani (n=30). Le EVs circolanti derivate da megacariociti (MK) e piastrine (PLT) sono state analizzate mediante citometria a flusso. Dopo l'estrazione del DNA microbico dalle feci e dalle EV isolate, è stata sequenziata la regione V3-V4 del 16S rDNA. La percentuale di EVs di MK era ridotta nei pazienti con PV rispetto ai donatori sani. Al contrario, la proporzione di EVs di PLT era aumentata. La PV è stata associata anche a una firma del DNA microbico delle EVs isolate con una maggiore diversità e una composizione microbica distinta rispetto alla controparte sana. Nei pazienti con PV c’è una maggiore proporzione di EVs associate al lipopolisaccaride. Il profilo del microbioma intestinale non differiva tra PV e doantori. Inoltre, l'aumento della proporzione di EVs di MK e la riduzione di EVs di piastre identificavano i pazienti con pregressa trombosi. Le EVs dei pazienti con trombosi erano impoverite di DNA di Staphylococcus ma arricchite di DNA di Actinobacteria e Anaerococcus. Inoltre, questi pazienti avevano livelli più bassi di EVs associate al lipopolisaccaride. I pazienti con fibrosi midollare avevano una maggiore proporzione di PE-EV ed erano arricchite in DNA di Collinsella e Flavobacterium. Questi dati possono contribuire a perfezionare la prognosi della PV e a identificare nuovi bersagli farmacologici.

Microenvironment and therapeutic modulation of myelofibrosis in an experimental mouse model.

Primary myelofibrosis(PMF) is the most severe form of Philadelphia-negative myeloproliferative neoplasms(MPNs), characterized by splenomegaly, extramedullary hematopoiesis and bone marrow(BM) fibrosis, with disease progression to leukemia and low survival. The best therapy currently available includes treatment with a JAK inhibitor(Ruxolitinib), which only ameliorates symptoms. Unfortunately, the pathogenesis of the disease is still poorly understood. It has been hypothesized that its progression may be determined by the presence of inflammatory cytokines produced by the bone marrow microenvironment that promote fibrosis. The three aims of this PhD thesis, using the Gata1low mouse model of myelofibrosis, were: 1. Investigate the presence of different cytokines in the bone marrow microenvironment; 2. Test the efficacy of treatment with Reparixin, a CXCR1/2 receptor inhibitor; 3. Test the efficacy of treatment with RB40.34 (P-selectin inhibitor), alone and in combination with Ruxolitinib. In the first study, we demonstrated by immunohistochemistry(IHC) the presence in the BM of Gata1low mice of elevated levels of CXCL1, and its receptors CXCR1/2, and TGF-β1. Particularly, the cells with higher expression of these cytokines were the megakaryocytes. In the second study, we found that treatment with Reparixin in Gata1low mice showed dose-dependent efficacy in reducing bone marrow and splenic fibrosis. Furthermore, by IHC analysis we demonstrated that the treatment induced a decrease in the expression of TGF-β1. In the third study, we found that treatment with RB40.34 in combination with Ruxolitinib normalizes the phenotype of Gata1low mice, reducing fibrosis and the content of TGF-β and CXCL1 in the bone marrow, and restoring the architecture of hematopoiesis in the bone marrow and spleen. In summary, these data provide preclinical evidence that treatment with Reparixin and RB40.34 in combination with Ruxolitinib are effective on reversing the myelofibrotic trait in the Gata1low mouse model and encourage clinical trials to validate these compounds in human patients with PMF.

Contribution of cytokines to the etiology and progression of Primary Myelofibrosis

Primary Myelofibrosis (PMF) is the end-stage of Philadelphia-negative myeloproliferative neoplasms (MPN) and is characterized by fibrosis and hematopoietic failure in bone marrow, with a consequential migration of the malignant hematopoietic stem cells (HSC) in the spleen where they induce ineffective haematopoiesis. To date, available therapies for PMF are still palliative and do not halt the progression of this neoplasm. During my PhD years, our laboratory investigated the factors promoting the onset and progression of PMF. In our PMF mice model, Gata1low mouse, we studied the role of the interaction of HSC niche with megakaryocytes and HSC localization in the bone marrow during their division and cycle. We observed the inflammation and the main protagonists (LNC-2, CXCL1, and TGF-β) of this process and how their level changes before and after the onset of the disease. We investigated the different megakaryocyte populations in the fibrotic environment in different organs (lung and bone marrow) to define the megakaryocytes implicated in this process. In human samples, we described different ultrastructural abnormalities of megakaryocytes from the bone marrow and the spleen, identifying a possible different metabolism in those two populations. In conclusion, we highlighted the intricated crosstalk between the megakaryocytes, the niche and HSC in PMF. We identified megakaryocytes-dependent cytokines altering the homeostasis of the niche and HSC. Those cytokines could be used as alternative therapeutic targets. Furthermore, we observed different megakaryocytic populations in different organs, providing new prospective on the role of megakaryocytes in different microenvironments.