Substrate Stiffness Regulates B-cell Activation, Proliferation, Class Switch, and T-cell-independent Antibody Responses in Vivo

Eur J Immunol. 2015 Jun;45(6):1621-34. doi: 10.1002/eji.201444777. Epub 2015 Apr 15.

Abstract

B cells use B-cell receptors (BCRs) to sense antigens that are usually presented on substrates with different stiffness. However, it is not known how substrate stiffness affects B-cell proliferation, class switch, and in vivo antibody responses. We addressed these questions using polydimethylsiloxane (PDMS) substrates with different stiffness (20 or 1100 kPa). Live cell imaging experiments suggested that antigens on stiffer substrates more efficiently trigger the synaptic accumulation of BCR and phospho-Syk molecules compared with antigens on softer substrates. In vitro expansion of mouse primary B cells shows different preferences for substrate stiffness when stimulated by different expansion stimuli. LPS equally drives B-cell proliferation on stiffer or softer substrates. Anti-CD40 antibodies enhance B-cell proliferation on stiffer substrates, while antigens enhance B-cell proliferation on softer substrates through a mechanism involving the enhanced phosphorylation of PI3K, Akt, and FoxO1. In vitro class switch differentiation of B cells prefers softer substrates. Lastly, NP67-Ficoll on softer substrates accounted for an enhanced antibody response in vivo. Thus, substrate stiffness regulates B-cell activation, proliferation, class switch, and T cell independent antibody responses in vivo, suggesting its broad application in manipulating the fate of B cells in vitro and in vivo.

Keywords: B-cell activation; Class switch; PDMS; Proliferation; Substrate stiffness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody Formation / immunology*
  • Antigen Presentation / immunology
  • Antigens / chemistry
  • Antigens / immunology*
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / metabolism*
  • Cell Proliferation
  • Dimethylpolysiloxanes / chemistry
  • Forkhead Transcription Factors / metabolism
  • Immunoglobulin Class Switching / genetics*
  • Immunoglobulin Class Switching / immunology*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Lymphocyte Activation / immunology*
  • Mice
  • Nylons / chemistry
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Phosphotyrosine / metabolism
  • Protein Binding
  • Protein Transport
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Antigen, B-Cell / metabolism
  • Syk Kinase
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism

Substances

  • Antigens
  • Dimethylpolysiloxanes
  • Forkhead Transcription Factors
  • Intracellular Signaling Peptides and Proteins
  • Nylons
  • Receptors, Antigen, B-Cell
  • poly(dimethylsiloxane)-polyamide copolymer
  • Phosphotyrosine
  • Phosphatidylinositol 3-Kinases
  • Protein-Tyrosine Kinases
  • Syk Kinase
  • Syk protein, mouse
  • Proto-Oncogene Proteins c-akt