Articles by Simaan Assi in JoVE
Isolement et caractérisation de neutrophiles avec des propriétés anti-tumorales Ronit Vogt Sionov1, Simaan Assi1, Maya Gershkovitz1, Jitka Y. Sagiv1, Lola Polyansky1, Inbal Mishalian2, Zvi G. Fridlender2, Zvi Granot1 1Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Hebrew University Medical School, 2Institute of Pulmonary Medicine, Hadassah-Hebrew University Medical Center
Other articles by Simaan Assi on PubMed
Saturated-efferocytosis Generates Pro-resolving CD11b Low Macrophages: Modulation by Resolvins and Glucocorticoids European Journal of Immunology. Feb, 2011 | Pubmed ID: 21268007 During the resolution phase of inflammation, apoptotic leukocytes are efferocytosed by macrophages in a nonphlogistic fashion that results in diminished responses to bacterial moieties and production of anti-inflammatory cytokines. Complement receptor 3 and pro-resolving lipid mediators promote the engulfment of apoptotic leukocytes by macrophages. Here, we present evidence for the emergence of pro-resolving, CD11b(low) macrophages in vivo during the resolution of murine peritonitis. These macrophages are distinct from the majority of peritoneal macrophages in terms of their functional protein expression profile, as well as pro-resolving properties, such as apoptotic leukocyte engulfment, indifference to TLR ligands, and emigration to lymphoid organs. Notably, we also found macrophages convert from the CD11b(high) to the CD11b(low) phenotype upon interaction with apoptotic cells ex vivo. In addition, we found that the pro-resolving lipid mediators resolvin E1 and D1, and the glucocorticoid dexamethasone regulated pro-resolving macrophage functions in vivo. This regulation culminated in a novel pro-resolving function, namely reducing the apoptotic leukocyte ingestion requirement for CD11b(low) macrophage generation. These new phenotype and molecular pathway markers define the new satiated macrophage. Thus, we suggest that satisfying efferocytosis generates CD11b(low) macrophages that are essential for complete nonphlogistic containment of inflammatory agents and the termination of acute inflammation.
Heat Acclimation and Exercise Training Interact when Combined in an Overriding and Trade-off Manner: Physiologic-genomic Linkage American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Dec, 2011 | Pubmed ID: 21957158 Combined heat acclimation (AC) and exercise training (EX) enhance exercise performance in the heat while meeting thermoregulatory demands. We tested the hypothesis that different stress-specific adaptations evoked by each stressor individually trigger similar cardiac alterations, but when combined, overriding/trade-off interactions take place. We used echocardiography, isolated cardiomyocyte imaging and cDNA microarray techniques to assay in situ cardiac performance, excitation-contraction (EC) coupling features, and transcriptional programs associated with cardiac contractility. Rat groups studied were controls (sedentary 24°C); AC (sedentary, 34°C, 1 mo); normothermic EX (treadmill at 24°C, 1 mo); and heat-acclimated, exercise-trained (EXAC; treadmill at 34°C, 1 mo). Prolonged heat exposure decreased heart rate and contractile velocity and increased end ventricular diastolic diameter. Compared with controls, AC/EXAC cardiomyocytes demonstrated lower l-type Ca(2+) current (I(CaL)) amplitude, higher Ca(2+) transient (Ca(2+)T), and a greater Ca(2+)T-to-I(CaL) ratio; EX alone enhanced I(CaL) and Ca(2+)T, whereas aerobic training in general induced cardiac hypertrophy and action potential elongation in EX/EXAC animals. At the genomic level, the transcriptome profile indicated that the interaction between AC and EX yields an EXAC-specific molecular program. Genes affected by chronic heat were linked with the EC coupling cascade, whereas aerobic training upregulated genes involved with Ca(2+) turnover via an adrenergic/metabolic-driven positive inotropic response. In the EXAC cardiac phenotype, the impact of chronic heat overrides that of EX on EC coupling components and heart rate, whereas EX regulates cardiac morphometry. We suggest that concerted adjustments induced by AC and EX lead to enhanced metabolic and mechanical performance of the EXAC heart.
Phenotypic Diversity and Plasticity in Circulating Neutrophil Subpopulations in Cancer Cell Reports. Feb, 2015 | Pubmed ID: 25620698 Controversy surrounds neutrophil function in cancer because neutrophils were shown to provide both pro- and antitumor functions. We identified a heterogeneous subset of low-density neutrophils (LDNs) that appear transiently in self-resolving inflammation but accumulate continuously with cancer progression. LDNs display impaired neutrophil function and immunosuppressive properties, characteristics that are in stark contrast to those of mature, high-density neutrophils (HDNs). LDNs consist of both immature myeloid-derived suppressor cells (MDSCs) and mature cells that are derived from HDNs in a TGF-β-dependent mechanism. Our findings identify three distinct populations of circulating neutrophils and challenge the concept that mature neutrophils have limited plasticity. Furthermore, our findings provide a mechanistic explanation to mitigate the controversy surrounding neutrophil function in cancer.