Neuroimmune cardiovascular interfaces control atherosclerosis.

Atherosclerotic plaques develop in the inner intimal layer of arteries and can cause heart attacks and strokes1. As plaques lack innervation, the effects of neuronal control on atherosclerosis remain unclear. However, the immune system responds to plaques by forming leukocyte infiltrates in the outer connective tissue coat of arteries (the adventitia)2-6. Here, because the peripheral nervous system uses the adventitia as its principal conduit to reach distant targets7-9, we postulated that the peripheral nervous system may directly interact with diseased arteries. Unexpectedly, widespread neuroimmune cardiovascular interfaces (NICIs) arose in mouse and human atherosclerosis-diseased adventitia segments showed expanded axon networks, including growth cones at axon endings near immune cells and media smooth muscle cells. Mouse NICIs established a structural artery-brain circuit (ABC): abdominal adventitia nociceptive afferents10-14 entered the central nervous system through spinal cord T6-T13 dorsal root ganglia and were traced to higher brain regions, including the parabrachial and central amygdala neurons; and sympathetic efferent neurons projected from medullary and hypothalamic neurons to the adventitia through spinal intermediolateral neurons and both coeliac and sympathetic chain ganglia. Moreover, ABC peripheral nervous system components were activated: splenic sympathetic and coeliac vagus nerve activities increased in parallel to disease progression, whereas coeliac ganglionectomy led to the disintegration of adventitial NICIs, reduced disease progression and enhanced plaque stability. Thus, the peripheral nervous system uses NICIs to assemble a structural ABC, and therapeutic intervention in the ABC attenuates atherosclerosis.

Analysis of nonleukemic cellular subcompartments reconstructs clonal evolution of acute myeloid leukemia and identifies therapy-resistant preleukemic clones.

To acquire a better understanding of clonal evolution of acute myeloid leukemia (AML) and to identify the clone(s) responsible for disease recurrence, we have comparatively studied leukemia-specific mutations by whole-exome-sequencing (WES) of both the leukemia and the nonleukemia compartments derived from the bone marrow of AML patients. The T-lymphocytes, B-lymphocytes and the functionally normal hematopoietic stem cells (HSC), that is, CD34+ /CD38- /ALDH+ cells for AML with rare-ALDH+ blasts (<1.9% ALDH+ cells) were defined as the nonleukemia compartments. WES identified 62 point-mutations in the leukemia compartment derived from 12 AML-patients at the time of diagnosis and 73 mutations in 3 matched relapse cases. Most patients (8/12) showed 4 to 6 point-mutations per sample at diagnosis. Other than the mutations in the recurrently mutated genes such as DNMT3A, NRAS and KIT, we were able to identify novel point-mutations that have not yet been described in AML. Some leukemia-specific mutations and cytogenetic abnormalities including DNMT3A(R882H), EZH2(I146T) and inversion(16) were also detectable in the respective T-lymphocytes, B-lymphocytes and HSC in 5/12 patients, suggesting that preleukemia HSC might represent the source of leukemogenesis for these cases. The leukemic evolution was reconstructed for five cases with detectable preleukemia clones, which were tracked in follow-up and relapse samples. Four of the five patients with detectable preleukemic mutations developed relapse. The presence of leukemia-specific mutations in these nonleukemia compartments, especially after chemotherapy or after allogeneic stem cell transplantation, is highly relevant, as these could be responsible for relapse. This discovery may facilitate the identification of novel targets for long-term cure.

Reduced hematopoietic stem cell frequency predicts outcome in acute myeloid leukemia.

In patients with acute myeloid leukemia and low percentages of aldehyde-dehydrogenase-positive cells, non-leukemic hematopoietic stem cells can be separated from leukemic cells. By relating hematopoietic stem cell frequencies to outcome we detected poor overall- and disease-free survival of patients with low hematopoietic stem cell frequencies. Serial analysis of matched diagnostic and follow-up samples further demonstrated that hematopoietic stem cells increased after chemotherapy in patients who achieved durable remissions. However, in patients who eventually relapsed, hematopoietic stem cell numbers decreased dramatically at the time of molecular relapse demonstrating that hematopoietic stem cell levels represent an indirect marker of minimal residual disease, which heralds leukemic relapse. Upon transplantation in immune-deficient mice cases with low percentages of hematopoietic stem cells of our cohort gave rise to leukemic or no engraftment, whereas cases with normal hematopoietic stem cell levels mostly resulted in multi-lineage engraftment. Based on our experimental data, we propose that leukemic stem cells have increased niche affinity in cases with low percentages of hematopoietic stem cells. To validate this hypothesis, we developed new mathematical models describing the dynamics of healthy and leukemic cells under different regulatory scenarios. These models suggest that the mechanism leading to decreases in hematopoietic stem cell frequencies before leukemic relapse must be based on expansion of leukemic stem cells with high niche affinity and the ability to dislodge hematopoietic stem cells. Thus, our data suggest that decreasing numbers of hematopoietic stem cells indicate leukemic stem cell persistence and the emergence of leukemic relapse.

N,N-diethylaminobenzaldehyde targets aldehyde dehydrogenase to eradicate human pancreatic cancer cells.

Pancreatic cancer is a common cause of worldwide cancer-related mortality with a poor 5-year survival rate. Aldehyde dehydrogenase (ALDH) activity is a possible marker for malignant stem cells in solid organ systems, including the pancreas, and N,N-diethylaminobenzaldehyde (DEAB) is able to inhibit ALDH activity. In the present study, the role of DEAB in the treatment of pancreatic cancer cells and the potential underlying mechanisms were investigated. The ALDH activities of pancreatic cancer cell lines treated with or without DEAB were analyzed by an ALDEFLUOR™ assay. The Cell Counting Kit-8 and colony formation assays, and cell cycle analysis were used to evaluate the viability, colony-forming ability and cell quiescence of cell lines under DEAB treatment, respectively. DEAB and/or gemcitabine-induced cell apoptosis was assessed by flow cytometry. DEAB reduced ALDH activity and inhibited the proliferation, colony-forming ability and cell quiescence of pancreatic cancer cell lines. Compared with respective controls, DEAB alone and the combination of gemcitabine and DEAB significantly decreased cell viability and increased cell apoptosis. Moreover, reverse transcription-PCR and western blotting were used to measure the expressions of B cell lymphoma 2 (Bcl2) associated X protein (Bax) and Bcl2 mRNA and protein. The anti-cancer effect of DEAB was associated with upregulation of Bax expression. Therefore, targeting ALDH with DEAB may be a potential therapeutic choice for pancreatic cancer, demonstrating a synergic effect with gemcitabine.

The molecular signature of AML with increased ALDH activity suggests a stem cell origin.

Enrichment of leukemic blasts with a stem cell phenotype correlates with poor survival in acute myeloid leukemia (AML). In this context, measurement of the stem cell marker aldehyde-dehydrogenase (ALDH) activity can distinguish poor prognosis cases with increased fractions of ALDH-positive cells (ALDH-numerous AML) and favorable outcome cases with low percentages (ALDH-rare AML). It has been shown that ALDH-numerous AML favor leukemic engraftment in xenotransplantation assays which suggests increased leukemic stem cell (LSC) potential. To test if this reflects an immature cell of origin, comparative gene-expression studies of CD34+ leukemic blasts were performed. This analysis revealed increased expression of LSC and HSC signatures in ALDH-numerous AML, whereas ALDH-rare AML were enriched for a progenitor signature. The enrichment of stemness-associated transcriptional programs suggests that ALDH-numerous AML derive from immature hematopoietic progenitors and offers an explanation for the poor prognosis and therapy resistance of this subgroup which is likely caused by inherited stem cell properties.