Priming by chemokines restricts lateral mobility of the adhesion receptor LFA-1 and restores adhesion to ICAM-1 nano-aggregates on human mature dendritic cells

PLoS One. 2014 Jun 19;9(6):e99589. doi: 10.1371/journal.pone.0099589. eCollection 2014.

Abstract

LFA-1 is a leukocyte specific β2 integrin that plays a major role in regulating adhesion and migration of different immune cells. Recent data suggest that LFA-1 on mature dendritic cells (mDCs) may function as a chemokine-inducible anchor during homing of DCs through the afferent lymphatics into the lymph nodes, by transiently switching its molecular conformational state. However, the role of LFA-1 mobility in this process is not yet known, despite that the importance of lateral organization and dynamics for LFA-1-mediated adhesion regulation is broadly recognized. Using single particle tracking approaches we here show that LFA-1 exhibits higher mobility on resting mDCs compared to monocytes. Lymphoid chemokine CCL21 stimulation of the LFA-1 high affinity state on mDCs, led to a significant reduction of mobility and an increase on the fraction of stationary receptors, consistent with re-activation of the receptor. Addition of soluble monomeric ICAM-1 in the presence of CCL21 did not alter the diffusion profile of LFA-1 while soluble ICAM-1 nano-aggregates in the presence of CCL21 further reduced LFA-1 mobility and readily bound to the receptor. Overall, our results emphasize the importance of LFA-1 lateral mobility across the membrane on the regulation of integrin activation and its function as adhesion receptor. Importantly, our data show that chemokines alone are not sufficient to trigger the high affinity state of the integrin based on the strict definition that affinity refers to the adhesion capacity of a single receptor to its ligand in solution. Instead our data indicate that nanoclustering of the receptor, induced by multi-ligand binding, is required to maintain stable cell adhesion once LFA-1 high affinity state is transiently triggered by inside-out signals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemokine CCL21 / genetics
  • Chemokine CCL21 / metabolism*
  • Chemokine CCL21 / pharmacology
  • Dendritic Cells / cytology
  • Dendritic Cells / drug effects
  • Dendritic Cells / metabolism*
  • Gene Expression Regulation
  • Humans
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism*
  • Intercellular Adhesion Molecule-1 / pharmacology
  • Ligands
  • Lymphocyte Function-Associated Antigen-1 / genetics
  • Lymphocyte Function-Associated Antigen-1 / metabolism*
  • Monocytes / cytology
  • Monocytes / drug effects
  • Monocytes / metabolism*
  • Primary Cell Culture
  • Protein Aggregates
  • Protein Binding
  • Protein Transport
  • Signal Transduction
  • Solubility

Substances

  • CCL21 protein, human
  • Chemokine CCL21
  • Ligands
  • Lymphocyte Function-Associated Antigen-1
  • Protein Aggregates
  • Intercellular Adhesion Molecule-1

Grants and funding

This work was supported by grant MAT2011-22887 from the Plan Nacional Immunanoforce (http://www.idi.mineco.gob.es) (MFG-P) (http://www.idi.mineco.gob.es/%29%28MFG-P%29), grant RGP0027/2012 from the Human Frontier Science Program (http://www.hfsp.org/) (MFG-P and AC) and by the European Commission (FP7-ICT-2011-7, under grant agreement No. 288263) to MFG-P and AC (http://www.nanovista.eu). AC is the recipient of a Meervoud grant (836.09.002) from The Netherlands Organisation for Scientific Research (NWO) (http://www.nwo.nl/en). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.