Institut de recherche biomédicale
     

    Research program

    •  
    • Cross talk between signaling, intracellular trafficking and cytoskeleton during phagocytosis in macrophages

      Phagocytosis depends on reorganization of cortical actin coordinated with the recruitment of intracellular compartments, which fuse with the plasma membrane, a process necessary to extend pseudopods around the particle internalized [1- 6]. We showed that mDia1, an actin nucleator of the formin family, is required downstream of the CR3 integrin receptors [7]. We also highlighted an original dialogue between the cytoskeleton microtubules and actin, based on CLIP-170, a protein that binds and stabilizes the plus ends of microtubules, and mDia1 [8].

    We further showed a that the protein B cell lymphoma/leukemia-10 (Bcl10), well known for its role in stimulating immune responses via NF-kB, is unexpectedly involved in cytoskeletal reorganization during phagocytosis in monocytes and macrophages by controlling the traffic of intracellular vesicles bearing the AP1 adaptors and the OCRL phosphatase [9, 10].  We developed an original method based on evanescent wave microscopy to monitor the spatiotemporal reorganization of membrane and actin in nascent phagosomes in three dimensions [11]. We revealed the role of dynamin2 in the control of phagosome formation and closure [12]. We are currently using the method to address questions on CR3 mediated-phagocytosis and on phagosome closure.

     

     

    • Perturbations of the phagocytic and activation functions of macrophages by viral infections (HIV, respiratory virus) and bacterial co-infections.

                                                                                                                                                                                                                                                                                                                                                                                                                            Macrophages are a major initial target of the human immunodeficiency virus (HIV) and represent a productive reservoir for the virus because of their resistance to cytopathic effects. Infection of macrophages by HIV-1 causes a severe impairment of the functions of these cells, which allows the development of opportunistic pathogens. We demonstrated that macrophages infected with HIV-1 exhibit defects in phagocytosis, which are due to one of its major virulence factors, Nef [13]. More recently, we showed that the Vpr viral protein interacts with microtubule associated motors, which impairs phagosome maturation and bacterial clearance [14] implicating the MICAL-L1/ EHD3 machinery [15]. We continue to characterize the development of opportunistic bacteria, especially Salmonella Typhimurium strains emerged in African HIV-1-infected patients (coll Dr Melita Gordon, Liverpool and Malawi).

    Alveolar macrophages are the most abundant innate immune cells present in the airways and are thought to play a crucial role in airway homeostasis. In chronic obstructive pulmonary disease (COPD), their numbers are increased and they are considered as key drivers of the pathogenesis of COPD through defective clearance capacities and exaggerated inflammatory responses [16]. The infection of alveolar macrophages with respiratory viruses is often implicated in exacerbation and emergence of bacterial co-infections. We are currently dissecting the mechanisms leading to this defective phagocytosis. The work is performed in collaboration with Astra Zeneca (Sweden)/ MedImmune and Prof. Pierre-Regis Burgel (Hôpital Cochin).

     

    • Capture by dendritic cells and antigen recycling.

    We described in dendritic cells (DCs) a mechanism of recycling to the extracellular milieu of non-degraded material from late endocytic compartments that we called “regurgitation” [17]. This is regulated by the small G protein Rab27 and the chemokine CXCL13, which is essential to attract B lymphocytes in the lymph nodes. B cells require recognition of native antigen to be activated, but how this encounter occurs is still unclear. Our results reveal a unique property of dendritic cells that might play an important role in the activation of B lymphocytes [17,18].

    We now analyze the molecular machineries regulating this type of recycling in DCs. We also analyze the antigen transfer between DCs and B cells in lymph nodes using intravital microscopy and will determine the development of humoral immune responses in vivo.

     

     

    REFERENCES

    1. Niedergang F., Phagocytosis. In: Ralph A Bradshaw and Philip D Stahl (Editors-in-Chief), Encyclopedia of Cell Biology, Vol 2, Waltham, MA: Academic Press, 2016, pp. 751-757.

    2. Braun, V., Deschamps, C., Raposo, G., Benaroch, P., Benmerah, A., Chavrier, P., and Niedergang, F. (2007). AP-1 and ARF1 Control Endosomal Dynamics at Sites of FcR mediated Phagocytosis. Mol Biol Cell 18, 4921-4931.

    3. Braun, V., Fraisier, V., Raposo, G., Hurbain, I., Sibarita, J.B., Chavrier, P., Galli, T., and Niedergang, F. (2004). TI-VAMP/VAMP7 is required for optimal phagocytosis of opsonised particles in macrophages. Embo J 23, 4166-4176.

    4. Niedergang, F., Colucci-Guyon, E., Dubois, T., Raposo, G., and Chavrier, P. (2003). ADP ribosylation factor 6 is activated and controls membrane delivery during phagocytosis in macrophages. J. Cell Biol. 161, 1143-1150.

    5. Braun, V., and Niedergang, F. (2006). Linking exocytosis and endocytosis during phagocytosis. Biol Cell 98, 195-201.

    6. Niedergang F, Di Bartolo V, Alcover A. (2016) Comparative Anatomy of Phagocytic and Immunological Synapses. Front Immunol. 7:18.

    7. Colucci-Guyon, E., Niedergang, F., Wallar, B.J., Peng, J., Alberts, A.S., and Chavrier, P. (2005). A role for mammalian diaphanous-related formins in complement receptor (CR3)-mediated phagocytosis in macrophages. Curr Biol 15, 2007-2012.

    8. Lewkowicz, E., Herit, F., Le Clainche, C., Bourdoncle, P., Perez, F., and Niedergang, F. (2008). The microtubule-binding protein CLIP-170 coordinates mDia1 and actin reorganization during CR3-mediated phagocytosis The Journal of Cell Biology 183, 1287-1298.

    9. Marion, S., Mazzolini, J., Herit, F., Bourdoncle, P., Kambou-Pene, N., Hailfinger, S., Sachse, M., Ruland, J., Benmerah, A., Echard, A., et al. (2012). The NF-kappaB Signaling Protein Bcl10 Regulates Actin Dynamics by Controlling AP1 and OCRL-Bearing Vesicles. Dev Cell 23, 954-967

    10. Deschamps C, Echard A and Niedergang F. Phagocytosis and cytokinesis : do cells share common tools ? (2013) Traffic 4, 355-364. Review

    11. Marie-Anaïs F, Mazzolini J, Bourdoncle P and Niedergang F. (2016). “Phagosome Closure Assay” to visualize phagosome formation in three dimensions using Total Internal Fluorescent Microscopy (TIRFM). JoVE in press.

    12. Marie-Anaïs F, Mazzolini J, Herit F and Niedergang F. (2016). Dynamin-actin cross-talk contributes to phagosome formation and closure. Traffic 17, 487-499.

    13. Mazzolini, J., Herit, F., Bouchet, J., Benmerah, A., Benichou, S., and Niedergang, F. (2010). Inhibition of phagocytosis in HIV-1-infected macrophages relies on Nef-dependent alteration of focal delivery of recycling compartments. Blood 115, 4226-4236.

    14. Dumas A., Lê‑Bury G., Marie‑Anaïs F., Herit F., Mazzolini J., Guilbert T., Bourdoncle P., Russell D.G., Benichou S., Zahraoui A.,  and Niedergang F. (2015). The HIV-1 protein Vpr impairs phagosome maturation by controlling microtubule-dependent trafficking. J. Cell Biol. 211 : 359-372.

    15. Abou-Zeid, N., Pandjaitan, R., Sengmanivong, L., David, V., Le Pavec, G., Salamero, J., and Zahraoui, A. (2011). MICAL-like1 mediates epidermal growth factor receptor endocytosis. Mol Biol Cell 22, 3431-3441.

    16. Jubrail, J., Kurian, N., and Niedergang, F. (2017). Macrophage phagocytosis cracking the defect code in COPD. Biomed. J. In press.

    17. Le Roux, D., Le Bon, A., Dumas, A., Taleb, K., Sachse, M., Sikora, R., Julithe, M., Benmerah, A., Bismuth, G., and Niedergang, F. (2012). Antigen stored in dendritic cells after macropinocytosis is released unprocessed from late endosomes to target B cells. Blood 119, 95-105.

    18. Le Roux, D., and Niedergang, F. (2012). New insights into antigen encounter by B cells. Immunobiology 217, 1285-1291. Review.