Recent studies have implicated the innate immunity system in the pathogenesis of myelodysplastic syndromes (MDS). Toll-like receptor (TLR) genes encode key innate immunity signal initiators. We recently identified multiple genes, known to be regulated by TLRs, to be overexpressed in MDS bone marrow (BM) CD34+ cells, and hypothesized that TLR signaling is abnormally activated in MDS. We analyzed a large cohort of MDS cases and identified that TLR1, 2 and 6 to be significantly overexpressed in MDS BM CD34+ cells. Deep-sequencing followed by Sanger-resequencing of TLR1, 2, 4 and 6 genes uncovered a recurrent genetic variant, TLR2-F217S, in 11% of 149 patients. Functionally, TLR2-F217S results in enhanced activation of downstream signaling including NF-kB activity after TLR2 agonist treatment. In cultured primary BM CD34+ cells of normal donors, TLR2 agonists induced histone demethylase JMJD3 and interleukin-8 gene expression. Inhibition of TLR2 in BM CD34+ cells from patients with lower-risk MDS using shRNA resulted in increased erythroid colony formation. Finally, RNA expression levels of TLR2 and 6 as well as presence of TLR2-F217S are associated with distinct prognosis and clinical characteristics. These findings indicate that TLR2-centered signaling is deregulated in MDS and that its targeting may have potential therapeutic benefit in MDS.

The molecular bases of myelodysplastic syndromes (MDS) are not fully understood. Trimethylated histone 4 lysine 3 (H3K4me3) is present in promoters of actively transcribed genes and has been shown to be involved in hematopoietic differentiation. We performed a genome-wide H3K4me3 CHIP-Seq analysis of primary MDS bone marrow (BM) CD34+ cells. This resulted in the identification of 36 genes marked by distinct higher levels of promoter H3K4me3 in MDS. A majority of these genes are involved in NF-kB activation and innate immunity signaling. We then analyzed expression of histone demethylases and observed significant overexpression of the JmjC-domain histone demethylase JMJD3 (KDM6b) in MDS CD34+ cells. Furthermore, we demonstrated that JMJD3 has a positive effect on transcription of multiple CHIP-Seq identified genes involved in NF-kB activation. Inhibition of JMJD3 using shRNA in primary BM MDS CD34+ cells resulted in an increased number of erythroid colonies in samples isolated from patients with lower-risk MDS. Taken together, these data indicate the deregulation of H3K4me3 and associated abnormal activation of innate immunity signals play a role in the pathogenesis of MDS and that targeting these signals may have potential therapeutic value in MDS.

In tumour lysis syndrome (TLS), metabolic alterations caused by the destruction of malignant cells manifest as laboratory abnormalities with (clinical TLS) or without (laboratory TLS) organ dysfunction. This prospective multicentre cohort study included 153 consecutive patients with malignancies at high risk for TLS (median age 54 years (interquartile range, 38-66). Underlying malignancies were acute leukaemia (58%), aggressive non-Hodgkin lymphoma (29.5%), and Burkitt leukaemia/lymphoma (12.5%). Laboratory TLS developed in 17 (11.1%) patients and clinical TLS with acute kidney injury (AKI) in 30 (19.6%) patients. After adjustment for confounders, admission phosphates level (odds ratio [OR] per mmol/l, 5.3; 95% confidence interval [95% CI], 1.5-18.3), lactic dehydrogenase (OR per x normal, 1.1; 95%CI, 1.005-1.25), and disseminated intravascular coagulation (OR, 4.1; 95%CI, 1.4-12.3) were associated with clinical TLS; and TLS was associated with day-90 mortality (OR, 2.45; 95%CI, 1.09-5.50; P = 0.03). In this study, TLS occurred in 30.7% of high-risk patients. One third of all patients experienced AKI, for which TLS was an independent risk factor. TLS was associated with increased mortality, indicating a need for interventional studies aimed at decreasing early TLS-related deaths in this setting.

MYD88 is a key mediator of Toll-like receptor innate immunity signaling. Oncogenically active MYD88 mutations have recently been reported in lymphoid malignancies, but has not been described in MDS. To characterize MYD88 in MDS, we sequenced the coding region of the MYD88 gene in 40 MDS patients. No MYD88 mutation was detected. We next characterized MYD88 expression in bone marrow CD34+ cells (N = 64). Increased MYD88 RNA was detected in 40% of patients. Patients with higher MYD88 expression in CD34+ cells had a tendency for shorter survival compared to the ones with lower MYD88, which was significant when controlled for IPSS and age. We then evaluated effect of MYD88 blockade in the CD34+ cells of patients with lower-risk MDS. Colony formation assays indicated that MYD88 blockade using a MYD88 inhibitor resulted in increased erythroid colony formation. MYD88 blockade also negatively regulated the secretion of interleukin-8. Treatment of MDS CD34+ cells with an IL-8 antibody also increased formation of erythroid colonies. These results indicate that MYD88 plays a role in the pathobiology of MDS and may have prognostic and therapeutic value in the management of patients with this disease.