Increase of bone marrow macrophages and CD8+ T lymphocytes predict graft failure after allogeneic bone marrow or cord blood transplantation.

Graft failure (GF) remains an obstacle to survival after allogeneic hematopoietic stem cell transplantation. However, differentiating GF from delayed engraftment (DE) can be difficult. Host CD8+ lymphocytes have been reported to mediate graft rejection, but the impact of macrophages on DE or GF is yet to be clarified. Peri-engraftment bone marrow (BM) specimens of 32 adult patients with normal engraftment, DE or GF were retrospectively evaluated to identify the potential associations of CD163+ macrophage and CD8+ lymphocyte infiltration into BM. The macrophage or CD8+ lymphocyte number/total nucleated cell number was defined as the Mac ratio and CD8 ratio, respectively. Both DE and GF groups had significantly higher Mac ratios at day 14 than the normal group (P<0.0001), but no significant difference was observed between the DE and GF groups (P=1.000). The CD8 ratio at day 14 was significantly higher in the GF than in the normal group (P=0.005), whereas the CD8 ratios of the DE and normal groups were similar (P=0.07). A high Mac ratio at day 14 was associated with a risk of DE or subsequent GF. Patients with increased CD8 ratio at day 14 had a further risk of GF. The Mac ratio and the CD8 ratio appear to be well suited for predicting engraftment status.

Proteasome inhibitors exert cytotoxicity and increase chemosensitivity via transcriptional repression of Notch1 in T-cell acute lymphoblastic leukemia.

The Notch signaling pathway has been recognized as a key factor for the pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL), because of the high incidence of activating mutations of Notch1. Notch inhibition could serve as a new treatment strategy for T-ALL; however, the attempts to perturb Notch signaling pathways have been unsuccessful so far. In this study, we found that proteasome inhibitors exert cytotoxic effects on T-ALL cells with constitutive activation of Notch1 to a similar extent as myeloma cells. The proteasome inhibitor bortezomib repressed the transcription of Notch1 and downstream effectors including Hes1, GATA3, RUNX3 and nuclear factor-κB (NF-κB) (p65 and p50), coincided with downregulation of the major transactivator Sp1 and its dissociation from Notch1 promoter. Overexpression of the Notch1 intracellular domain (NICD) significantly ameliorated bortezomib-induced cytotoxicity against T-ALL cells. Drug combination studies revealed that bortezomib showed synergistic or additive effects with key drugs for the treatment of T-ALL such as dexamethasone (DEX), doxorubicin and cyclophosphamide, which were readily abolished by NICD overexpression. The synergy of bortezomib and DEX was confirmed in vivo using a murine xenograft model. Our findings provide a molecular basis and rationale for the inclusion of proteasome inhibitors in treatment strategies for T-ALL.

Clinical significance of hemophagocytosis in BM clot sections during the peri-engraftment period following allogeneic hematopoietic SCT.

The effects of macrophage activation on the outcome of allogeneic hematopoietic SCT (allo-HSCT) have yet to be fully examined. A total of 70 adult patients who received a first allo-HSCT for hematological diseases were studied. We counted the number of hemophagocytic cells in BM clot sections on day +14±7, and analyzed its impact on subsequent outcome. In all, 23 patients were diagnosed as having increased numbers of hemophagocytic cells (HP group), whereas 47 were not (non-HP group). The HP group was not associated with an increased incidence of acute or chronic GVHD, but was associated with worse hematopoietic recovery than the non-HP group. The 2-year OS for the HP group and the non-HP group was 30 and 65% (P<0.01), respectively, and 2-year non-relapse mortality was 48% and 27% (P<0.01), respectively. Multivariate analysis confirmed that the HP group was associated with a lower OS (hazard ratio (HR)=2.3; 95% confidence interval (CI), 1.0-5.4; P=0.048) and higher non-relapse mortality (HR=4.0; 95% CI, 1.6-9.9; P<0.01). The HP group had higher incidences of death due to graft failure (P<0.01) and endothelial complications, such as sinusoidal obstruction syndrome and transplant-associated microangiopathy (P=0.01). Macrophage activation is a previously unrecognized complication with negative impact on outcome of allo-HSCT.

The enhanced production of hyaluronic acid by cultured rat fibroblast cells treated with cyclic AMP and its dibutyryl derivative.

Cells of a newly established rat fibroblast line (SEN) in culture synthesize mucopolysaccharides, which have been identified as hyaluronic acid, chondroitin-4-sulfate and heparan sulfate. Treatment of the cells with adenosine 3':5'-cyclic monophosphate resulted in a marked stimulation of production of hyaluronic acid, but not of the other mucopolysaccharides. Treated cells also showed increased activity of hyaluronic acid synthetase, a reduction in growth rate, and morphological alteration. In addition, 5-bromodeoxyuridine was found to counteract greatly the cyclic AMP effect.