CCL28 Has Dual Roles in Mucosal Immunity as a Chemokine with Broad-Spectrum Antimicrobial Activity

Abstract

CCL28 is a CC chemokine signaling via CCR10 and CCR3 that is selectively expressed in certain mucosal tissues such as exocrine glands, trachea, and colon. Notably, these tissues commonly secrete low-salt fluids. RT-PCR analysis demonstrated that salivary glands expressed CCL28 mRNA at the highest levels among various mouse tissues. Single cells prepared from mouse parotid glands indeed contained a major fraction of CD3−B220low cells that expressed CCR10 at high levels and CCR3 at low levels and responded to CCL28 in chemotaxis assays. Morphologically, these cells are typical plasma cells. By immunohistochemistry, acinar epithelial cells in human and mouse salivary glands were strongly positive for CCL28. Furthermore, human saliva and milk were found to contain CCL28 at high concentrations. Moreover, the C terminus of human CCL28 has a significant sequence similarity to histatin-5, a histidine-rich candidacidal peptide in human saliva. Subsequently, we demonstrated that human and mouse CCL28 had a potent antimicrobial activity against Candida albicans, Gram-negative bacteria, and Gram-positive bacteria. The C-terminal 28-aa peptide of human CCL28 also displayed a selective candidacidal activity. In contrast, CCL27, which is most similar to CCL28 and shares CCR10, showed no such potent antimicrobial activity. Like most other antimicrobial peptides, CCL28 exerted its antimicrobial activity in low-salt conditions and rapidly induced membrane permeability in target microbes. Collectively, CCL28 may play dual roles in mucosal immunity as a chemoattractant for cells expressing CCR10 and/or CCR3 such as plasma cells and also as a broad-spectrum antimicrobial protein secreted into low-salt body fluids.

CC Chemokine Ligands 25 and 28 Play Essential Roles in Intestinal Extravasation of IgA Antibody-Secreting Cells

“…After washing, cells were incubated with streptavidin-allophycocyanin for 30 min. For surface staining of CCR9, CCR10, and CXCR4, mouse CCL25-Fc, human CCL27-Fc, mouse CXCL12-Fc, respectively, and control Fc were used, as described previously (13). After staining, cells were immediately analyzed on a FACSCalibur (BD Biosciences, Mountain View, CA).…”

“…This was performed using 8-m Transwell plates (Corning Costar, Cambridge, MA), as described previously (13). Briefly, cells were placed in upper wells (2 ϫ 10 6 /well), while bottom wells contained medium alone or medium containing chemokines at concentrations that were predetermined to be optimal (300 nM for CCL25, 300 nM for CCL28, and 50 nM for CXCL12) (13,14).…”

“…Briefly, cells were placed in upper wells (2 ϫ 10 6 /well), while bottom wells contained medium alone or medium containing chemokines at concentrations that were predetermined to be optimal (300 nM for CCL25, 300 nM for CCL28, and 50 nM for CXCL12) (13,14). After incubation at 37°C for 4 h, migrated cells in multiple replicate wells (generally 4 -5 wells per each condition) were combined.…”

“…Bowman et al (10) reported that IgA ASCs, but not IgG or IgM ASCs, in mice expressed CCR9 and efficiently responded to its ligand CCL25, which is selectively expressed in the small intestine (11,12). Previously, we have demonstrated that plasma cells in mouse salivary glands as well as those in human bone marrow selectively express CCR10 and respond to its ligand CCL28 (13,14), which is selectively expressed in certain mucosal tissues and human bone marrow (13)(14)(15)(16). Butcher and coworkers (17,18) have also demonstrated that CCL28 attracts IgA ASCs present in both intestinal and nonintestinal mucosal tissues, while CCL25 only attracts a subpopulation of IgA ASCs associated with small intestine.…”

Temporal Production of CCL28 Corresponds to Eosinophil Accumulation and Airway Hyperreactivity in Allergic Airway Inflammation

“…13 Although little is known about the regulation of CCL28, it has been shown to mediate both eosinophil and T-cell recruitment in vitro, in addition to playing a role in mucosal immunity because of potent broad-spectrum antimicrobial activity. [13][14][15] CCL28, like CCL27, has been identified as a ligand for CCR10/GPR2 13 however Pan and colleagues 14 have demonstrated that the functional effects of CCL28 are also mediated by CCR3. We investigated the pattern of CCL28 expression within normal and allergen-challenged lungs and examined the role of CCL28 in a murine model of allergic airway inflammation.…”