Circulating HMGB1 is increased in myelodysplastic syndrome but not in other bone marrow failure syndromes: proof-of-concept cross-sectional study.

Background: Myelodysplastic syndrome (MDS) is associated with persistent immune activation. High mobility group box-1 (HMGB1) is a ubiquitous, functionally diverse, non-histone intranuclear protein. During acute and chronic inflammatory states, HMGB1 is actively released by inflammatory cells, further amplifying the inflammatory response. A role in MDS and other hypoplastic bone marrow (BM) disorders is incompletely understood. Objectives: The objective of the study is to evaluate whether circulating HMGB1 is elevated in patients with MDS and other BM failure syndromes [namely, aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH)]. Design: This is a observational, cross-sectional, single-center, exploratory study. Methods: We evaluated circulating concentrations of HMGB1, interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α in patients with MDS and age-matched hematologically healthy controls as well as patients with AA and PNH. Results: We included 66 patients with MDS and 65 age-matched controls as well as 44 patients with other BM failures (AA = 27, PNH = 17). Circulating levels of HMGB1 were higher in patients with MDS [median, 4.9 ng/ml; interquartile range (IQR): 2.3-8.1] than in AA (median, 2.6 ng/ml; IQR: 1.7-3.7), PNH (median, 1.7 ng/ml; IQR: 0.9-2.5), and age-matched healthy individuals (median, 1.9 ng/ml; IQR: 0.9-2.5) (p = 0.0001). We observed higher concentrations of HMGB1 in the very low/low-risk MDS patients than in the intermediate/high/very high-risk ones (p = 0.046). Finally, in comparison with patients with AA, those with hypocellular MDS (h-MDS) had significantly higher levels of circulating HMGB1 (n = 14; median concentration, 5.6 ng/ml, IQR: 2.8-7.3; p = 0.006). We determined a circulating HMGB1 value of 4.095 ng/ml as a diagnostic cutoff differentiator between h-MDS and AA. Conclusion: These observations indicate that circulating HMGB1 is increased in patients with MDS. HMGB1 (but not IL-1ß or TNF-α) differentiated between MDS and other BM failures, suggesting that HMGB1 may be mechanistically involved in MDS and a druggable target to decrease inflammation in MDS.