Tuberculosis is associated with expansion of a motile, permissive and immunomodulatory CD16(+) monocyte population via the IL-10/STAT3 axis

The human CD14+ monocyte compartment is composed by two subsets based on CD16 expression. We previously reported that this compartment is perturbed in tuberculosis (TB) patients, as reflected by the expansion of CD16+ monocytes along with disease severity. Whether this unbalance is beneficial or detrimental to host defense remains to be elucidated. Here in the context of active TB, we demonstrate that human monocytes are predisposed to differentiate towards an anti-inflammatory (M2-like) macrophage activation program characterized by theCD16+CD163+MerTK+pSTAT3+ phenotype and functional properties such as enhanced protease-dependent motility, pathogen permissivity and immunomodulation. This process is dependent on STAT3 activation, and loss-of-function experiments point towards a detrimental role in host defense against TB. Importantly, we provide a critical correlation between the abundance of the CD16+CD163+MerTK+pSTAT3+ cells and the progression of the disease either at the local level in a non-human primate tuberculous granuloma context, or at the systemic level through the detection of the soluble form of CD163 in human sera. Collectively, this study argues for the pathogenic role of the CD16+CD163+MerTK+pSTAT3+ monocyte-to-macrophage differentiation program and its potential as a target for TB therapy,and promotes the detection of circulating CD163 as a potential biomarker for disease progression and monitoringof treatment efficacy.Fil: Lastrucci, Claire. Centre National de la Recherche Scientifique; FranciaFil: Bénard, Alan. Centre National de la Recherche Scientifique; FranciaFil: Balboa, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Pingris, Karine. Centre National de la Recherche Scientifique; FranciaFil: Souriant, Shanti. Centre National de la Recherche Scientifique; FranciaFil: Poincloux, Renaud. Centre National de la Recherche Scientifique; FranciaFil: Al Saati, Talal. Inserm; FranciaFil: Rasolofo, Voahangy. Pasteur Institute in Antananarivo; MadagascarFil: González Montaner, Pablo. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Inwentarz, Sandra. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Moraña, Eduardo José. Gobierno de la Ciudad de Buenos Aires. Hospital de Infecciosas ; ArgentinaFil: Kondova, Ivanela. Biomedical Primate Research Centre; Países BajosFil: Verreck, Franck A. W.. Biomedical Primate Research Centre; Países BajosFil: Sasiain, María del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Neyrolles, Olivier. Centre National de la Recherche Scientifique; FranciaFil: Maridonneau Parini, Isabel. Centre National de la Recherche Scientifique; FranciaFil: Lugo Villarino, Geanncarlo. Centre National de la Recherche Scientifique; FranciaFil: Cougoule, Celine. Centre National de la Recherche Scientifique; Franci

Regulation of Phagocyte Migration by Signal Regulatory Protein-Alpha Signaling

Signaling through the inhibitory receptor signal regulatory protein-alpha (SIRPα) controls effector functions in phagocytes. However, there are also indications that interactions between SIRPα and its ligand CD47 are involved in phagocyte transendothelial migration. We have investigated the involvement of SIRPα signaling in phagocyte migration in vitro and in vivo using mice that lack the SIRPα cytoplasmic tail. During thioglycolate-induced peritonitis in SIRPα mutant mice, both neutrophil and macrophage influx were found to occur, but to be significantly delayed. SIRPα signaling appeared to be essential for an optimal transendothelial migration and chemotaxis, and for the amoeboid type of phagocyte migration in 3-dimensional environments. These findings demonstrate, for the first time, that SIRPα signaling can directly control phagocyte migration, and this may contribute to the impaired inflammatory phenotype that has been observed in the absence of SIRPα signalin

Regulation of Phagocyte Migration by Signal Regulatory Protein-Alpha Signaling

Signaling through the inhibitory receptor signal regulatory protein-alpha (SIRPα) controls effector functions in phagocytes. However, there are also indications that interactions between SIRPα and its ligand CD47 are involved in phagocyte transendothelial migration. We have investigated the involvement of SIRPα signaling in phagocyte migration in vitro and in vivo using mice that lack the SIRPα cytoplasmic tail. During thioglycolate-induced peritonitis in SIRPα mutant mice, both neutrophil and macrophage influx were found to occur, but to be significantly delayed. SIRPα signaling appeared to be essential for an optimal transendothelial migration and chemotaxis, and for the amoeboid type of phagocyte migration in 3-dimensional environments. These findings demonstrate, for the first time, that SIRPα signaling can directly control phagocyte migration, and this may contribute to the impaired inflammatory phenotype that has been observed in the absence of SIRPα signaling

Dynamic life and death interactions between Mycobacterium smegmatis and J774 macrophages

After internalization into macrophages non-pathogenic mycobacteria are killed within phagosomes. Pathogenic mycobacteria can block phagosome maturation and grow inside phagosomes but under some conditions can also be killed by macrophages. Killing mechan

Pharmacological Activation of Guanine Nucleotide Exchange Factors for the Small GTPase Rap1 Recruits High-Affinity β1 Integrins as Coreceptors for Parvovirus B19: Improved Ex Vivo Gene Transfer to Human Erythroid Progenitor Cells

Parvovirus B19 has potential as a gene therapy vector because of its restricted tropism for human erythroid progenitor cells in the bone marrow. B19 binds to the cell surface through P antigen and we identified activated β1 integrins as coreceptors for internalization. Because differentiation with phorbol ester induces β1 integrin coreceptor activity, but cell differentiation is not desirable in gene transfer to human progenitor cells and one of the downstream effectors of phorbol esters is the small GTPase Rap1, the role of Rap1 in the recruitment of β1 integrins on hematopoietic cells was examined. Expression of a constitutively active Rap1 (63E) was sufficient to recruit β1 integrin coreceptors in erythroleukemic K562 cells by inducing high-affinity integrin conformation. A crucial role of actin polymerization in Rap1-mediated β1 integrin recruitment was documented by complete inhibition of the 63E Rap1 effect with low-dose cytochalasin D and by the ability of a constitutively active mutant of the actin cytoskeleton regulator Rac1 to sensitize K562 cells to the pharmacological activation of endogenous Rap1, using the Rap1 exchange factor-specific 8-pCPT-2′-O-Me-cAMP [8-(4-chlorophenylthio)-2′-O-methyladenosine-3′,5′-cyclic monophosphate]. Interestingly, in primary human erythroid progenitor cells, 8-pCPT-2′-O-Me-cAMP was sufficient to significantly increase B19-mediated gene transfer, suggesting that these cells possess the cytoskeleton organization capacity required for efficient recruitment of β1 integrins by brief pharmacological stimulation of Rap1 GTP loading. Because 8-pCPT-2′-O-Me-cAMP has been implicated in enhanced homing of progenitor cells, these results identify a novel tool with which to optimize ex vivo B19-mediated gene transfer and potentially improve homing of transduced cells by Rap1–β1 integrin activation with 8-pCPT-2′-O-Me-cAMP

2D transwell chemotaxis and transendothelial migration are impaired in SIRPα^Δcyt phagocytes.

<p>A) C5a-induced 2D migration in transwell chemotaxis assay is regulated by SIRPα signaling. Data shown represents the difference between the maximum and the minimum fluorescent value reached within 1 h in BMDN and 2 h in BMDM. Values shown represent averages ± SEM of n = 4 independent experiments. Asterisk, p≤0,05. B) Transendothelial migration is deficient in SIRPα^<b>Δcyt</b> BMDN. WT and SIRPα^<b>Δcyt</b> BMDN were seeded over a mrTNFα-stimulated monolayer of bEnd5 cells. After 5’ a flow ratio of 0.9dyn/cm^<b>2</b> was applied and transendothelial migration was monitored by time lapse video microscopy using a phase-contrast lens. Data shown represent means ± SEM of 12 measurements done in 3 independent experiments. Asterisk, p≤0,05. C) BMDN and BMDM from SIRPα^<b>Δcyt</b> mice have similar levels of integrin expression. Cells were cultured as described in material and methods and stained with specific Abs against the indicated integrins. Gating was based on FCS and SSC. Histograms from representative experiments are shown for BMDN and BMDM. The dotted line represents the isotype control wile the continuous line represents WT (gray filled) or SIRPα^<b>Δcyt</b> (no filling) stainings.</p