Differential Use of Chondroitin Sulfate to Regulate Hyaluronan Binding by Receptor CD44 in Inflammatory and Interleukin 4-activated Macrophages

Abstract

CD44 is a cell surface receptor for the extracellular matrix glycosaminoglycan hyaluronan and is involved in processes ranging from leukocyte recruitment to wound healing. In the immune system, the binding of hyaluronan to CD44 is tightly regulated, and exposure of human peripheral blood monocytes to inflammatory stimuli increases CD44 expression and induces hyaluronan binding. Here we sought to understand how mouse macrophages regulate hyaluronan binding upon inflammatory and anti-inflammatory stimuli. Mouse bone marrow-derived macrophages stimulated with tumor necrosis factor ␣ or lipopolysaccharide and interferon-␥ (LPS/IFN␥) induced hyaluronan binding by up-regulating CD44 and down-regulating chondroitin sulfation on CD44. Hyaluronan binding was induced to a lesser extent in interleukin-4 (IL-4)-activated macrophages despite increased CD44 expression, and this was attributable to increased chondroitin sulfation on CD44, as treatment with ␤-D-xyloside to prevent chondroitin sulfate addition significantly enhanced hyaluronan binding. These changes in the chondroitin sulfation of CD44 were associated with changes in mRNA expression of two chondroitin sulfotransferases, CHST3 and CHST7, which were decreased in LPS/IFN␥-stimulated macrophages and increased in IL-4-stimulated macrophages. Thus, inflammatory and anti-inflammatory stimuli differentially regulate the chondroitin sulfation of CD44, which is a dynamic physiological regulator of hyaluronan binding by CD44 in mouse macrophages.Macrophages differentiate from peripheral blood monocytes upon recruitment to the tissues. Under homeostatic conditions this process occurs constitutively to maintain a population of resident macrophages that provide a first line of defense against invading microorganisms (for review, see Refs. 1 and 2). This is of particular importance in some tissues, such as the lungs, where phagocytosis of bacteria by resident alveolar macrophages can be sufficient to clear infection (3). During inflammatory conditions, recruitment of a different subpopulation of monocytes occurs, and the number of macrophages in the tissues is greatly increased. Macrophages initially undergo "classical activation" in response to IFN␥ and toll-like receptor (TLR) 6 ligands such as LPS and display increased anti-microbial abilities due to increased production of reactive nitrogen and oxygen species (for review, see Refs. 4 and 5). The production of proinflammatory and T helper cell 1 (T H 1)-polarizing cytokines by these LPS-and IFN␥-polarized (M1) macrophages affects both the local and systemic immune response. Recruited macrophages are also important for resolving inflammation, as they phagocytose inflammation-inducing agents such as bacteria, cellular debris, and degraded extracellular matrix components (6, 7). Furthermore, increased levels of anti-inflammatory or T helper cell 2 (T H 2)-polarizing cytokines such as IL-4 result in the "alternative activation" of macrophages. These alternatively activated (M2) macrophages produce anti-inflammatory cytokines ...

Membrane cholesterol modulates the hyaluronan-binding ability of CD44 in T lymphocytes and controls rolling under shear flow

“…4). The clustered particles formed agglomerations of gold signals of 100-300 nm in size in the untreated cells ( Johnson and others have intensively investigated the regulation of CD44 function, and shown that post-translational modifications to CD44 are implicated in modulating its HA-binding ability (Katoh et al, 1995;English et al, 1998;Skelton et al, 1998;Levesque and Haynes, 1999;Ruffell et al, 2011;Maiti et al, 1998;Brown et al, 2001). Under the conditions described here, however, the involvement of post-translational modifications may not matter, since the HA-binding ability of CD44 rose within 30 minutes (Fig.…”

“…In fact, CD44 on resting T cells does not bind HA, but can be induced to bind it upon T cell activation with antigen via the T cell receptor (TCR) (DeGrendele et al, 1997;Lesley et al, 1994;Ariel et al, 2000;Firan et al, 2006;Maeshima et al, 2011). Studies report that various posttranslational modifications on CD44, including glycosylation (Katoh et al, 1995;English et al, 1998;Skelton et al, 1998), chondroitin sulfate addition (Levesque and Haynes, 1999;Ruffell et al, 2011), and sulfation (Maiti et al, 1998;Brown et al, 2001), affect its HA-binding ability. However, the membrane-based regulation of CD44's HA-binding ability has not been clarified.…”

Hyaluronan Binding Identifies a Functionally Distinct Alveolar Macrophage–like Population in Bone Marrow–Derived Dendritic Cell Cultures

“…Specific environments and the cytokine milieu likely contribute to this phenotypic, and possibly functional, heterogeneity. For example, the addition of IL-4 to M-CSF-induced bone marrow-derived macrophages (BMDMs) upregulates CD11c and downregulates F4/80 (10). Whereas peritoneal and splenic red pulp macrophages are positive for F4/80 and CD11b, alveolar macrophages express low levels of these classical macrophage markers and high levels of CD11c (6,11).…”

“…CD44 is the major cell-surface receptor for HA on immune cells, but not all CD44-expressing cells bind HA (29,30). On human monocytes, CD44 can be induced to bind HA by various inflammatory cytokines including GM-CSF, IL-1a and IL-1b, and TNF-a (25,31), and M-CSF-derived BMDMs only bind HA after they are stimulated with M1 or M2 polarizing agents (10). However, the functional significance of this induced binding remains enigmatic.…”

“…Activated human blood monocytes and M1 (LPS and IFN-g) and M2 (IL-4) polarized M-CSF-induced murine BMDMs have been shown to bind hyaluronan (HA), a major component of the extracellular matrix (10,25). HA is present in virtually all tissues.…”