1 3 Eur Biophys J (2014) 43:573–579 DOI 10.1007/s00249-014-0988-3 REVIEW Macrophage adhesion on ﬁbronectin evokes an increase in the elastic property of the cell membrane and cytoskeleton: an atomic force microscopy study Samuel T. Souza · Laís C. Agra · Cássio E. A. Santos · Emiliano Barreto · Jandir M. Hickmann · Eduardo J. S. Fonseca Received: 12 March 2014 / Revised: 31 August 2014 / Accepted: 8 September 2014 / Published online: 19 October 2014 © European Biophysical Societies’ Association 2014 actin cytoskeleton to the elastic properties of the cell. Our ﬁndings show that cell adhesion inﬂuences the mechanical properties of the plasma membrane, provid- ing new information toward understanding the inﬂuence of the ECM on elastic alterations of macrophage cell membranes. Keywords Atomic force microscopy · Elastic modulus · Nanoindentation · Extracellular matrix · Cytoskeleton · Fibronectin Introduction Macrophages play an important role in immune response and tissue homeostasis. The ability of macrophages to perform phagocytosis renders them effective at killing microbes and clearing apoptotic and necrotic cells (Gordon 2003; Gordon and Martinez 2010; Kreider et al. 2007). The hallmarks of macrophage activation can be veriﬁed by cell adhesion and spreading on the extracellular matrix (ECM) (Collins 1987). Among the ECM components, ﬁbronec- tin (Fn) has been recognized as the key element promot- ing cell adhesion, among its other functions. Adhesion to Fn modulates the secretion of proinﬂammatory cytokines and contributes to cell migration through various tissues (Vesey et al. 2002). These functions are mediated by sur- face receptors, called integrins, which are present on mac- rophages (Hemler 1990). The migratory process involves a repeated, dynamic deformation and recovery of the plasma membrane; however, it is not yet fully understood whether this capacity for deformation is inﬂuenced by cell adhesion to the ECM. It has been hypothesized that one pathway by which mechanical stress regulates intracellular activity is via a direct physical connection of the ECM across the Abstract Interactions between cells and microenviron- ments are essential to cellular functions such as survival, exocytosis and differentiation. Cell adhesion to the extra- cellular matrix (ECM) evokes a variety of biophysical changes in cellular organization, including modiﬁcation of the cytoskeleton and plasma membrane. In fact, the cytoskeleton and plasma membrane are structures that mediate adherent contacts with the ECM; therefore, they are closely correlated. Considering that the mechanical properties of the cell could be affected by cell adhesion- induced changes in the cytoskeleton, the purpose of this study was to investigate the inﬂuence of the ECM on the elastic properties of ﬁxed macrophage cells using atomic force microscopy. The results showed that there was an increase (~50 %) in the Young’s modulus of macrophages adhered to an ECM-coated substrate as compared with an uncoated glass substrate. In addition, cytochalasin D-treated cells had a 1.8-fold reduction of the Young’s modulus of the cells, indicating the contribution of the S. T. Souza · E. J. S. Fonseca (*) Instituto de Física, Universidade Federal de Alagoas, Caixa Postal 2051, Maceió, AL 57061-970, Brazil e-mail: eduardo@ﬁs.ufal.br L. C. Agra · E. Barreto Laboratório de Biologia Celular, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas, Maceió, AL 57072-970, Brazil C. E. A. Santos · J. M. Hickmann · E. J. S. Fonseca Centro de Tecnologia-CTEC, Universidade Federal de Alagoas, Maceió, AL 57072-970, Brazil J. M. Hickmann Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, RS 91501-970, Brazil