Molecular analysis of neutrophil spontaneous apoptosis reveals a strong role for the pro-apoptotic BH3-only protein Noxa

Neutrophils enter the peripheral blood from the bone marrow and die after a short time. Molecular analysis of spontaneous neutrophil apoptosis is difficult as these cells die rapidly and cannot be easily manipulated. We use conditional Hoxb8 expression to generate mouse neutrophils and test the regulation of apoptosis by extensive manipulation of B-cell lymphoma protein 2 (Bcl-2)-family proteins. Spontaneous apoptosis was preceded by downregulation of anti-apoptotic Bcl-2 proteins. Loss of the pro-apoptotic Bcl-2 homology domain (BH3)-only protein Bcl-2-interacting mediator of cell death (Bim) gave some protection, but only neutrophils deficient in both BH3-only proteins, Bim and Noxa, were strongly protected against apoptosis. Function of Noxa was at least in part neutralization of induced myeloid leukemia cell differentiation protein (Mcl-1) in neutrophils and progenitors. Loss of Bim and Noxa preserved neutrophil function in culture, and apoptosis-resistant cells remained in circulation in mice. Apoptosis regulated by Bim- and Noxa-driven loss of Mcl-1 is thus the final step in neutrophil differentiation, required for the termination of neutrophil function and neutrophil-dependent inflammation.     

XIAP antisense oligonucleotide (AEG35156) achieves target knockdown and induces apoptosis preferentially in CD34<Superscript>+</Superscript>38<Superscript>−</Superscript> cells in a phase 1/2 study of patients with relapsed/refractory AML

XIAP, a potent caspase inhibitor, is highly expressed in acute myeloid leukemia (AML) cells and contributes to chemoresistance. A multi-center phase 1/2 trial of XIAP antisense oligonucleotide AEG35156 in combination with idarubicin/cytarabine was conducted in 56 patients with relapsed/refractory AML. Herein we report the pharmacodynamic studies of the patients enrolled at M. D. Anderson Cancer Center. A total of 13 patients were enrolled in our institution: five in phase 1 (12–350 mg/m² AEG35156) and eight in phase 2 (350 mg/m² AEG35156) of the protocol. AEG35156 was administered on 3 consecutive days and then weekly up to a maximum of 35 days. Blood samples were collected from patients on days 1 through 5 and on day 28–35 post-chemotherapy for detection of XIAP levels and apoptosis. AEG35156 treatment led to dose-dependent decreases of XIAP mRNA levels (42–100% reduction in phase 2 patients). XIAP protein levels were reduced in all five samples measured. Apoptosis induction was detected in 1/4 phase 1 and 4/5 phase 2 patients. Importantly, apoptosis was most pronounced in CD34 ⁺ 38 ⁻ AML stem cells and all phase 2 patients showing apoptosis induction in CD34 ⁺ 38 ⁻ cells achieved response. We conclude that at 350 mg/m², AEG35156 is effective in knocking down XIAP in circulating blasts accompanied by the preferential induction of apoptosis in CD34 ⁺ 38 ⁻ AML stem cells.     

Antibiotics and the resistant microbiome

Since the discovery and clinical application of antibiotics, pathogens and the human microbiota have faced a near continuous exposure to these selective agents. A well-established consequence of this exposure is the evolution of multidrug-resistant pathogens, which can become virtually untreatable. Less appreciated are the concomitant changes in the human microbiome in response to these assaults and their contribution to clinical resistance problems. Studies have shown that pervasive changes to the human microbiota result from antibiotic treatment and that resistant strains can persist for years. Additionally, culture-independent functional characterization of the resistance genes from the microbiome has demonstrated a close evolutionary relationship between resistance genes in the microbiome and in pathogens. Application of these techniques and novel cultivation methods are expected to significantly expand our understanding of the interplay between antibiotics and the microbiome.     

A simple and objective method for reproducible resting state network (RSN) detection in fMRI

Spatial Independent Component Analysis (ICA) decomposes the time by space functional MRI (fMRI) matrix into a set of 1-D basis time courses and their associated 3-D spatial maps that are optimized for mutual independence. When applied to resting state fMRI (rsfMRI), ICA produces several spatial independent components (ICs) that seem to have biological relevance - the so-called resting state networks (RSNs). The ICA problem is well posed when the true data generating process follows a linear mixture of ICs model in terms of the identifiability of the mixing matrix. However, the contrast function used for promoting mutual independence in ICA is dependent on the finite amount of observed data and is potentially non-convex with multiple local minima. Hence, each run of ICA could produce potentially different IC estimates even for the same data. One technique to deal with this run-to-run variability of ICA was proposed by [1] in their algorithm RAICAR which allows for the selection of only those ICs that have a high run-to-run reproducibility. We propose an enhancement to the original RAICAR algorithm that enables us to assign reproducibility p-values to each IC and allows for an objective assessment of both within subject and across subjects reproducibility. We call the resulting algorithm RAICAR-N (N stands for null hypothesis test), and we have applied it to publicly available human rsfMRI data (http://www.nitrc.org). Our reproducibility analyses indicated that many of the published RSNs in rsfMRI literature are highly reproducible. However, we found several other RSNs that are highly reproducible but not frequently listed in the literature.     

Pronounced hypoxia in models of murine and human leukemia: high efficacy of hypoxia-activated prodrug PR-104

Recent studies indicate that interactions between leukemia cells and the bone marrow (BM) microenvironment promote leukemia cell survival and confer resistance to anti-leukemic drugs. There is evidence that BM microenvironment contains hypoxic areas that confer survival advantage to hematopoietic cells. In the present study we investigated whether hypoxia in leukemic BM contributes to the protective role of the BM microenvironment. We observed a marked expansion of hypoxic BM areas in immunodeficient mice engrafted with acute lymphoblastic leukemia (ALL) cells. Consistent with this finding, we found that hypoxia promotes chemoresistance in various ALL derived cell lines. These findings suggest to employ hypoxia-activated prodrugs to eliminate leukemia cells within hypoxic niches. Using several xenograft models, we demonstrated that administration of the hypoxia-activated dinitrobenzamide mustard, PR-104 prolonged survival and decreased leukemia burden of immune-deficient mice injected with primary acute lymphoblastic leukemia cells. Together, these findings strongly suggest that targeting hypoxia in leukemic BM is feasible and may significantly improve leukemia therapy.     

Synthesis and antitubercular activity of 2-hydroxy-aminoalkyl derivatives of diaryloxy methano phenanthrenes

A series of 2-hydroxy-aminoalkyl derivatives of diaryloxy methano phenanthrenes were synthesized from nucleophilic opening of oxirane with different amines. These compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis H(37)R(v) in vitro and showed MIC in the range of 3.12-25microg/ml.