Proteomic Signature Reveals Modulation of Human Macrophage Polarization and Functions Under Differing Environmental Oxygen Conditions.

Macrophages are innate immune cells which can react to a large number of environmental stimuli thanks to a high degree of plasticity. These cells are involved in a variety of tissue functions in homeostasis, and they play essential roles in pathological contexts. Macrophages' activation state, which determines their functional orientation, is strongly influenced by the cellular environment. A large body of macrophage literature is devoted to better defining polarizations from a molecular viewpoint. It is now accepted that a multidimensional model of polarization is needed to grasp the broad phenotype repertoire controlled by environmental signals. The study presented here aimed, among other goals, to provide a molecular signature of various polarizations in human macrophages at the protein level to better define the different macrophage activation states. To study the proteome in human monocyte-derived macrophages as a function of their polarization state, we used a label-free quantification approach on in-gel fractionated and LysC/Trypsin digested proteins. In total, 5102 proteins were identified and quantified for all polarization states. New polarization-specific markers were identified and validated. Because oxygen tension is an important environmental parameter in tissues, we explored how environmental oxygen tension, at either atmospheric composition (18.6% O2) or "tissue normoxia" (3% O2), affected our classification of macrophage polarization. The comparative results revealed new polarization-specific makers which suggest that environmental oxygen levels should be taken into account when characterizing macrophage activation states. The proteomic screen revealed various polarization-specific proteins and oxygen sensors in human macrophages. One example is arachidonate 15-lipoxygenase (ALOX15), an IL4/IL13 polarization-specific protein, which was upregulated under low oxygen conditions and is associated with an increase in the rate of phagocytosis of apoptotic cells. These results illustrate the need to consider physicochemical parameters like oxygen level when studying macrophage polarization, so as to correctly assess their functions in tissue.

Identification of AREG and PLK1 pathway modulation as a potential key of the response of intracranial 9L tumor to microbeam radiation therapy.

Synchrotron microbeam radiation therapy (MRT) relies on the spatial fractionation of a synchrotron beam into parallel micron-wide beams allowing deposition of hectogray doses. MRT controls the intracranial tumor growth in rodent models while sparing normal brain tissues. Our aim was to identify the early biological processes underlying the differential effect of MRT on tumor and normal brain tissues. The expression of 28,000 transcripts was tested by microarray 6 hr after unidirectional MRT (400 Gy, 50 µm-wide microbeams, 200 µm spacing). The specific response of tumor tissues to MRT consisted in the significant transcriptomic modulation of 431 probesets (316 genes). Among them, 30 were not detected in normal brain tissues, neither before nor after MRT. Areg, Trib3 and Nppb were down-regulated, whereas all others were up-regulated. Twenty-two had similar expression profiles during the 2 weeks observed after MRT, including Ccnb1, Cdc20, Pttg1 and Plk1 related to the mitotic role of the Polo-like kinase (Plk) pathway. The up-regulation of Areg expression may indicate the emergence of survival processes in tumor cells triggered by the irradiation; while the modulation of the "mitotic role of Plk1" pathway, which relates to cytokinetic features of the tumor observed histologically after MRT, may partially explain the control of tumor growth by MRT. The identification of these tumor-specific responses permit to consider new strategies that might potentiate the antitumoral effect of MRT.

Influence of oxygen tension on CD133 phenotype in human glioma cell cultures.

Under standard culture conditions, tumor cells are exposed to 20% O(2), whereas the mean tumor oxygen levels within the tumor are much lower. We demonstrate, using low-passaged human tumor cell cultures established from glioma, that a reduction in the oxygen level in these cell cultures dramatically increases the percentage of CD133 expressing cells.

Effects of Tumor Necrosis Factor-α (TNFα) and Interferon-γ (IFNγ) on Gene Expression Profiles in Bladder Carcinoma Cells Using Oligonucleotide Microarray Analysis.

BACKGROUND: TNFα and IFNγ, two main cytokines secreted in the urine of bladder cancer patients after Bacillus Calmette Guerin immunotherapy (BCG therapy), exert various responses ranging from growth arrest, apoptosis, phenotypic changes and differentiation. MATERIALS AND METHODS: To identify their transcriptional and translational targets, the highly sensitive bladder cancer cell line (RT112) was treated for 24 hours with increasing doses of IFNγ or TNFα and analyzed for cellular and molecular changes using a cDNA microarray technique (Transcriptome) containing 800 genes. RESULTS: High doses (>10 ng/ml) induced an apoptotic cell death, whereas low doses (<5 ng/ml) induced a survival program. TNFα-inducible genes, IFNγ-inducible genes and genes modulated by TNFα and IFNγ together were identified. All were related to the tumor progression program including cell proliferation, apoptosis/survival, angiogenesis and metastatic processes. CONCLUSION: These results suggest that the transcriptomic approach could be a good methodology to determine the molecular mechanisms involved in bladder tumor progression processes in relation to a low response to BCG treatment. However, mRNA and protein expression did not always correlate, suggesting that translational regulation is a vital process in bladder tumor progression.