Leukotriene C4 induces migration of human monocyte-derived dendritic cells without loss of immunostimulatory function

Generation of human monocyte-derived dendritic cells (DCs) for cancer vaccination involves ex vivo maturation in the presence of proinflammatory cytokines and prostaglandin E(2) (PGE(2)). Although the inclusion of PGE(2) during maturation is imperative for the induction of DC migration, PGE(2) has unfavorable effects on the immunostimulatory capacity of these cells. Like PGE(2), leukotrienes (LTs) are potent mediators of DC migration. We therefore sought to characterize the migratory and immunologic properties of DCs that matured in the presence of LTB(4), LTC(4), LTD(4), and PGE(2). Here, we demonstrate that DCs matured in the presence of LTC(4), but not LTB(4) or LTD(4), are superior to PGE(2)-matured DCs in stimulating CD4(+) T-cell responses and in inducing antigen-specific cytotoxic T lymphocytes (CTLs) in vitro without concomitant induction or recruitment of regulatory T cells (Tregs). LTC(4)-matured DCs migrate efficiently through layers of extracellular matrix and secrete higher levels of immunostimulatory IL-12p70 while producing reduced levels of immune-inhibitory IL-10, IL12p40, indoleamine-2,3-dioxidase, and TIMP-1 (tissue inhibitor of matrix metalloproteinases). Intracellular calcium mobilization and receptor antagonist studies reveal that, in contrast to LTD(4), LTC(4) did not signal through CysLTR(1) in DCs. Collectively, our data suggest that LTC(4) represents a promising candidate to replace PGE(2) in DC maturation protocols for cancer vaccination.     

Safety and efficacy of brentuximab vedotin for Hodgkin lymphoma recurring after allogeneic stem cell transplantation

Hodgkin lymphoma (HL) relapsing after allogeneic stem cell transplantation (alloSCT) presents a major clinical challenge. In the present investigation, we evaluated brentuximab vedotin, a CD30-directed Ab-drug conjugate, in 25 HL patients (median age, 32 years; range, 20-56) with recurrent disease after alloSCT (11 unrelated donors). Patients were > 100 days after alloSCT, had no active GVHD, and received a median of 9 (range, 5-19) prior regimens. Nineteen (76%) had refractory disease immediately before enrollment. Patients received 1.2 or 1.8 mg/kg of brentuximab vedotin IV every 3 weeks (median, 8 cycles; range, 1-16). Overall and complete response rates were 50% and 38%, respectively, among 24 evaluable patients. Median time to response was 8.1 weeks, median progression-free survival was 7.8 months, and the median overall survival was not reached. Cough, fatigue, and pyrexia (52% each), nausea and peripheral sensory neuropathy (48% each), and dyspnea (40%) were the most frequent adverse events. The most common adverse events ≥ grade 3 were neutropenia (24%), anemia (20%), thrombocytopenia (16%), and hyperglycemia (12%). Cytomegalovirus was detected in 5 patients (potentially clinically significant in 1). These results support the potential utility of brentuximab vedotin for selected patients with HL relapsing after alloSCT.     

Clonal competition with alternating dominance in multiple myeloma

Emerging evidence indicates that tumors can follow several evolutionary paths over a patient's disease course. With the use of serial genomic analysis of samples collected at different points during the disease course of 28 patients with multiple myeloma, we found that the genomes of standard-risk patients show few changes over time, whereas those of cytogenetically high-risk patients show significantly more changes over time. The results indicate the existence of 3 temporal tumor types, which can either be genetically stable, linearly evolving, or heterogeneous clonal mixtures with shifting predominant clones. A detailed analysis of one high-risk patient sampled at 7 time points over the entire disease course identified 2 competing subclones that alternate in a back and forth manner for dominance with therapy until one clone underwent a dramatic linear evolution. With the use of the Vk*MYC genetically engineered mouse model of myeloma we modeled this competition between subclones for predominance occurring spontaneously and with therapeutic selection.     

Reduced methylation of the thromboxane synthase gene is correlated with its increased vascular expression in preeclampsia

Preeclampsia is characterized by increased thromboxane and decreased prostacyclin levels, which predate symptoms, and can explain some of the clinical manifestations of preeclampsia, including hypertension and thrombosis. In this study, we examined DNA methylation of the promoter region of the thromboxane synthase gene (TBXAS1) and the expression of thromboxane synthase in systemic blood vessels of normal pregnant and preeclamptic women. Thromboxane synthase is responsible for the synthesis of thromboxane A(2), a potent vasoconstrictor and activator of platelets. We also examined the effect of experimentally induced DNA hypomethylation on the expression of thromboxane synthase in a neutrophil-like cell line (HL-60 cells) and in cultured vascular smooth muscle and endothelial cells. We found that DNA methylation of the TBXAS1 promoter was decreased and thromboxane synthase expression was increased in omental arteries of preeclamptic women as compared with normal pregnant women. Increased thromboxane synthase expression was observed in vascular smooth muscles cells, endothelial cells, and infiltrating neutrophils. Experimentally induced DNA hypomethylation only increased expression of thromboxane synthase in the neutrophil-like cell line, whereas tumor necrosis factor-α, a neutrophil product, increased its expression in cultured vascular smooth muscle cells. Our study suggests that epigenetic mechanisms and release of tumor necrosis factor-α by infiltrating neutrophils could contribute to the increased expression of thromboxane synthase in maternal systemic blood vessels, contributing to the hypertension and coagulation abnormalities associated with preeclampsia.