Fig. 3.

The impact of ECM on immune cell function. The dense collagen-rich ECM of fibrotic tumors can act as a physical barrier to CTL infiltration into tumors. Increased ECM stiffness and aligned structural barriers in a fibrotic tumor also influence the localization and migration of T cells into the tumor stroma. Tumor-associated ECM components as well as sequestered chemokine factors can influence macrophage polarization (towards an M2 signature) and affect the maturation and migration of monocytes and MDSCs. Dense ECM architecture can also prompt changes in availability of oxygen and micronutrients, inducing hypoxia and thereby influencing the immune contexture of the tumor microenvironment