ALBERT

Description: Elevated plasma levels of the nucleoside diphosphate kinase (NDPK) NM23-H1 are associated with poorer prognosis in acute myeloid leukemia (AML). We previously demonstrated that leukemic blasts release NM23-H1, which binds to more differentiated myeloid cells inducing their secretion of inflammatory cytokines, including IL-1β, that promote survival and proliferation of leukemic blasts1. Both AML and myelodysplastic syndrome (MDS) patients are prone to infections due to impaired hematopoiesis that is worsened by treatment. NDPKs are highly evolutionarily conserved raising the possibility that bacterial/fungal NDPKs could mediate the same survival effect on malignant AML/MDS blasts and exacerbate disease progression. To test this, we generated recombinant NDPKs (rNDPKs) from bacteria and fungi associated with common infections in these patients (E. coli, S. aureus, S. pneumoniae, K. pneumoniae, C. albicans). Cytokine production and survival responses of primary AMLs to these proteins were indistinguishable from their response to rNM23-H1. This activity was independent of NDPK enzyme activity since mutant rNM23-H1 and bacterial and fungal rNDPKs with impaired oligomerization, kinase or exonuclease activity elicited the same cytokine and survival response. Toll like receptors (TLRs) are the major family of human DAMP/PAMP receptors and IL-1β secretion is closely associated with TLR-4 mediated activation of the NLRP3 inflammasome in monocytes. We therefore postulated that NM23-H1 and pathogen derived NDPKs act as novel damage- and pathogen- associated molecular pattern (DAMP, PAMP) molecules. We confirmed that fluorescently labelled rNM23-H1 and S. pneumoniae rNDPK bound selectively to monocytes in peripheral blood. Using in vitro generated monocytes (vitamin D3 differentiated THP-1 cells) we demonstrated that both wild type and mutant rNM23-H1 and bacterial/fungal rNDPKs induced activation of caspase-1 and cleavage of pro-IL-1β into its active form. Secretion of IL-1β was inhibited by antagonists/inhibitors of TLR4, NLRP3 and caspase-1 indicating the involvement of the TLR4-NLRP3 inflammasome axis is mediating the NDPK response. Unlike the canonical NLRP3-inflammasome pathway that leads to monocyte cell death by pyroptosis, rNM23-H1 and rNDPKs did not lead to cell death indicating that rNDPKs are responsible for the activation of the alternative inflammasome. In our earlier studies, and those of others, we demonstrated that not all AML primary samples responsed to NM23-H1 in vitro. We have observed that non responders to NM23-H1 also do not respond to pathogen derived rNDPKs. In contrast, we have observed uniform responses in terms of cytokine release in all normal peripheral blood. We hence hypothesized that the non-rNDPK-responding AML samples may reflect the absence of monocytes in culture. To test this, we generated conditioned media using normal donor leukocytes, in presence or absence of a TLR-4 antagonist to inhibit the IL-1β production. The conditioned media was then used to culture primary AML samples, in parallel with rNDPK in unconditioned media. All the samples analyzed showed increased survival in rNDPK conditioned media even whilst some did not respond to rNDPK in unconditioned media. In summary, our data demonstrate for the first time that NM23-H1 and bacterial/fungal NDPKs are novel DAMPs/PAMPS that signal via TLR4 in monocytes. We further demonstrate that this interaction results in activation of the alternative NLRP3 inflammasome and subsequent cleavage and secretion of IL-1β without death by pyroptosis. Our data showing that bacterial/fungal NDPKs can promote survival of AML blasts indicates that rather than just being a consequence of AML associated immunosuppression, infections may drive the progression and AML. These findings have important implications in the clinical management of AML and its precursor myelodysplastic syndromes (MDS). Lilly AJ, et al.Cancer Res. 2011;71(3):1177-86.Gaidt MM, et al. Immunity. 2016;44(4):833-46 Disclosures Drayson: Abingdon Health: Consultancy, Equity Ownership.

Description: Elevated circulating levels of NM23-H1 have been associated with poor prognosis in haematological malignancies including AML and non-Hodgkin's lymphomas. In diffuse large B-cell lymphoma (DLBCL), several studies have demonstrated that both elevated circulating plasma levels and intra-tumoural levels of NM23-H1 correlate with poorer prognosis. These observations bring into question whether the mechanistic link of NM23-H1 expression with DLBCL prognosis depends an intrinsic intracellular mechanisms or is mediated by release of NM23-H1. We have shown that DLBCL lymphoma cell lines (Farage, HT, OCI-LY1, OCI-LY3, OCI-LY7, SUDHL4, SUDHL5 SUDHL6, U2932) express both NM23-H1 protein and the highly related protein NM23-H2. We also demonstrated that DLBCL cell lines release significant levels of NM23-H1 into their extracellular environment but not NM23-H2. Release of NM23-H1 was highly variable between cell lines with some releasing very high levels and some releasing much lower levels. Thus, DLBCL cell lines represent appropriate models to investigate the role of high and low levels of NM23-H1 on prognosis. The DLBCL cell lines HT and OCI-LY1 where selected for further study as representative of high and low level releasers of NM23-H1, respectively. CRISPR-Cas9 knockout of NM23-H1 (KO-NM23-H1) in HT and OCI-LY1 DLBCL cells had no impact on cell growth, viability or immuno-phenotype either in normoxic or hypoxic cultures. Thus NM23-H1 appears to not be required intrinsically by DLBCL cell lines. We therefore considered that the link between higher expression and release of NM23-H1 with prognosis is mediated via tumour-host environment interactions. We used an NSG mouse model transplanted subcutaneously with 1x106 CRISPR control (CTRL)-HT, CTRL-OCIL-Y1, KO-NM23-H1-HT or KO-NM23-H1-OCI-LY1 cell lines. We did not observe significant differences in tumour growth between CTRL and KO-NM23-H1 cells in the low NM23-H1 expressing OCI-LY1 DLBCL cell line. However, the high-expressing KO-NM23-H1-HT cells had significantly slower tumour progression and increased host survival when compared to CTRL-HT cells. We interpret to indicate that NM23-H1 release above a certain threshold provides a tumour growth advantage. Reduced lymphocyte:monocyte ratios (LMR) are also associated with poor prognosis in DLBCL. To investigate a potential functional link between NM23-H1 release and monocyte behaviour we first exposed peripheral blood leucocytes to Alexa 647 labelled fluorescent recombinant-NM23-H1 and found that monocytes but not neutrophils, T-cells or B-cells bound NM23-H1. We also observed that monocyte viability and survival were elevated in serum free cultures when supplemented with rNM23-H1, an observation that might indicate that elevated circulating NM23-H1 and reduced LMR in poor prognosis DLBCL may be mechanistically linked. We next co- cultured CTRL-HT or koNM23-H1-HT in a 1:1 ratios with purified monocytes from healthy human donors. Principle component analyses of 27 cytokines simultaneously measured by luminex assays identified that IL-1β, IL-6, IL-8, MIP-1α, MIP-1β and TNF-α were elevated when monocytes were co-cultured with CTRL-HT cells compared to co-culture with koNm23-H1-HT cells. In contrast, IP-10 was found elevated in the co-culture with koNm23-H1-HT cells. These observations indicate potentially important cross talk between the malignant DLBCL cells and innate immune cells of the host. Consistent with this, IL-6 and IL-8 serum levels have been shown to be elevated in pretreatment DLBCL patients compared to control subjects and MIP-1α, IL-6, and IL-8 serum levels have a greater association with DLBCL than follicular lymphoma. In conclusion ours is the first study to investigate potential mechanistic links between the associations of elevated NM23-H1 and poor prognosis in DLBCL and indicate a role for cross-talk between tumour cells and innate immune cells. Our data also indicate that NM23-H1 release from DLBCL cells may be a driving component in driving reduced LMRs that are also associated with poor prognosis. Whether reduced LMR and NM23-H1 release are casually related or not, the possibility that patients with both elevated monocytes and elevated circulating NM23-H1 levels are likely to represent a group with particularly poor prognosis requires urgent investigation. Disclosures Drayson: Abingdon Health: Consultancy, Equity Ownership. Rushworth:Abbvie: Research Funding; Janssen: Research Funding.