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Background & Aims Fulminant hepatitis (FH) is a clinical syndrome characterized by sudden and severe liver dysfunction. Dot1L, a histone methyltransferase, is implicated in various physiologic and pathologic processes, including transcription regulation and leukemia. However, the role of Dot1L in regulating inflammatory responses during FH remains elusive. Methods Propionibacterium acnes (P. acnes)-primed, lipopolysaccharides (LPS)-induced FH was established in C57BL/6 mice and was treated with the Dot1L inhibitor EPZ-5676. Myeloid derived suppressor cells (MDSCs) were depleted by anti-Gr-1 antibody to evaluate their therapeutic roles in Dot1L treatment of FH. Moreover, peripheral blood of patients suffered with FH and healthy controls was collected to determine the expression profile of Dot1L-SOCS1-iNOS axis in their MDSCs. Results Here we identified that EPZ-5676, pharmacological inhibitor of Dot1L, attenuated the liver injury of mice subjected to FH. Dot1L inhibition led to decreased T helper 1 cell response and expansion of regulatory T cells (Tregs) during FH. Interestingly, Dot1L inhibition didn’t directly target T cells, but dramatically enhanced the immunosuppressive function of MDSCs. Mechanistically, Dot1L inhibition epigenetically suppressed SOCS1 expression, thus inducing inducible nitric oxide synthase (iNOS) expression in a STAT1-dependent manner. Moreover, in human samples, the levels of Dot1L and SOCS1 expression were upregulated in MDSCs, accompanied by decreased expression of iNOS in patients with FH, compared with healthy controls. Conclusions Altogether, our findings established Dot1L as a critical regulator of MDSC immunosuppressive function for the first time, and highlighted the therapeutic potential of Dot1L inhibitor for FH treatment., Graphical abstract

Leukemic stem cells (LSCs) are an emerging target of curative anti-leukemia therapy. In acute lymphoblastic leukemia (ALL), LSCs frequently express CD34 and often lack CD38. However, little is known about markers and targets expressed in ALL LSCs. We have examined marker- and target expression profiles in CD34+/CD38- LSCs in patients with Ph+ ALL (n = 22) and Ph- ALL (n = 27) by multi-color flow cytometry and qPCR. ALL LSCs expressed CD19 (B4), CD44 (Pgp-1), CD123 (IL-3RA), and CD184 (CXCR4) in all patients tested. Moreover, in various subgroups of patients, LSCs also displayed CD20 (MS4A1) (10/41 = 24%), CD22 (12/20 = 60%), CD33 (Siglec-3) (20/48 = 42%), CD52 (CAMPATH-1) (17/40 = 43%), IL-1RAP (13/29 = 45%), and/or CD135 (FLT3) (4/20 = 20%). CD25 (IL-2RA) and CD26 (DPPIV) were expressed on LSCs in Ph+ ALL exhibiting BCR/ABL1p210, whereas in Ph+ ALL with BCR/ABL1p190, LSCs variably expressed CD25 but did not express CD26. In Ph- ALL, CD34+/CD38- LSCs expressed IL-1RAP in 6/18 patients (33%), but did not express CD25 or CD26. Normal stem cells stained negative for CD25, CD26 and IL-1RAP, and expressed only low amounts of CD52. In xenotransplantation experiments, CD34+/CD38- and CD34+/CD38+ cells engrafted NSG mice after 12-20 weeks, and targeting with antibodies against CD33 and CD52 resulted in reduced engraftment. Together, LSCs in Ph+ and Ph- ALL display unique marker- and target expression profiles. In Ph+ ALL with BCR/ABL1p210, the LSC-phenotype closely resembles the marker-profile of CD34+/CD38- LSCs in chronic myeloid leukemia, confirming the close biologic relationship of these neoplasms. Targeting of LSCs with specific antibodies or related immunotherapies may facilitate LSC eradication in ALL.

Leukocyte cell-derived chemotaxin 2 (LECT2) is a secreted pleiotropic protein that is mainly produced by the liver. We have previously shown that LECT2 plays an important role in the pathogenesis of inflammatory liver diseases. Lipopolysaccharide/d-galactosamine (LPS/d-GalN)-induced acute liver injury is a known animal model of fulminant hepatic failure. Here we found that this hepatic injury was alleviated in LECT2-deficient mice. The levels of TNF-α and IFN-γ, which mediate this hepatitis, had significantly decreased in these mice, with the decrease in IFN-γ production notably greater than that in TNF-α. We therefore analyzed IFN-γ-producing cells in liver mononuclear cells. Flow cytometric analysis showed significantly reduced IFN-γ production in hepatic NK and NKT cells in LECT2-deficient mice compared with in wild-type mice. We also demonstrated a decrease in IFN-γ production in LECT2-deficient mice after systemic administration of recombinant IL-12, which is known to induce IFN-γ in NK and NKT cells. These results indicate that a decrease of IFN-γ production in NK and NKT cells was involved in the alleviation of LPS/d-GalN-induced liver injury in LECT2-deficient mice., Highlights • LECT2-deficient mice are less sensitive to LPS/d-GalN-induced hepatitis. • The IFN-γ level in hepatic NK and NKT cells is lower in LECT2-deficient mice. • IL-12-induced IFN-γ production is diminished in LECT2-deficient mice. • The pathological role of LECT2 in hepatitis could depend on the initiation of immune response cells.

Background & Aims Toll-like receptor 2 (TLR2) and TLR3 regulate hepatic immunity under pathological conditions, but their functions and potential drug targets in alcoholic liver disease (ALD) remain poorly understood. Methods ALD-associated liver injury were induced in TLR2 knockout (TLR2–/–), TLR3–/–, TLR2–/– bone marrow transplanted (BMT), TLR3–/– BMT, IL-10–/– mice, and their wild-type littermates through ethanol challenge with or without co-administered epigallocatechin-3-gallate (EGCG). Moreover, Kupffer cells were depleted by GdCl3 injection to evaluate their pathogenic roles in ALD. Results We identified that deficiency of TLR2 and TLR3 significantly alleviated and aggravated ALD-induced liver injury, respectively. Mechanistically, Kupffer cell inactivation, M1 to M2 polarization, and IL-10 production via STAT3 activation contributed to hepatic protection mediated by concurrent TLR2 inhibition and TLR3 agonism. These findings were further confirmed in TLR2 and TLR3 BMT mice. We also identified a novel ALD-protective agent EGCG which directly interacted with Kupffer cell TLR2/3 to induce IL-10 production. Deficiency of IL-10 aggravated ALD injury and blunted EGCG-mediated hepatoprotection while depletion of Kupffer cells partially recovered liver injury but abolished EGCG’s actions. Conclusions Altogether, our results illustrate the divergent roles of Kupffer cells TLR2/3 in ALD progression via anti-inflammatory cytokine IL-10 production., Graphical abstract

Increasing numbers of paediatric patients with congenital heart defects are surviving to adulthood, albeit with continuing clinical needs. Hence, there is still scope for revolutionary new strategies to correct vascular anatomical defects. Adult patients are also surviving longer with the adverse consequences of ischemic vascular disease, especially after acute coronary syndromes brought on by plaque erosion and rupture. Vascular tissue engineering and therapeutic angiogenesis provide new hope for these patients. Both approaches have shown promise in laboratory studies, but have not yet been able to deliver clear evidence of clinical success. More research into biomaterials, molecular medicine and cell and molecular therapies is necessary. This review article focuses on the new opportunities offered by targeting microRNAs for the improved production and greater empowerment of vascular cells for use in vascular tissue engineering or for increasing blood perfusion of ischemic tissues by amplifying the resident microvascular network., Graphical abstract Schematic of application of miRs in vascular tissue engineering. Cells from patient could be collected, expanded and be subjected to miR modulation strategies to generate cells of desired specification. Pluripotent stem cells can be modulated to inhibit self-renewal and promote differentiation toward a desired progenitor cell. Also miR modulation of the progenitor cells may permit maintenance of the cells in a progenitor state or differentiation toward specific progeny thereby facilitating a modular cell therapy strategy. The modified cells can be loaded onto scaffolds for implantation or can be used to generate intact tissues and organs in vitro before implantation in the patient. MiR modification strategies can also be used directly in ischemic tissues to regulate angiogenesis. Extracellular vesicles (EVs) carrying the ‘desired’ cargo of miR can be isolated from stem or progenitor cells for direct injection into ischemic tissue.