Gingiva Equivalents Secrete Negligible Amounts of Key Chemokines Involved in Langerhans Cell Migration Compared to Skin Equivalents

Abstract

Both oral mucosa and skin have the capacity to maintain immune homeostasis or regulate immune responses upon environmental assault. Whereas much is known about key innate immune events in skin, little is known about oral mucosa. Comparative studies are limited due to the scarce supply of oral mucosa for ex vivo studies. Therefore, we used organotypic tissue equivalents (reconstructed epithelium on fibroblast-populated collagen hydrogel) to study cross talk between cells. Oral mucosa and skin equivalents were compared regarding secretion of cytokines and chemokines involved in LC migration and general inflammation. Basal secretion, representative of homeostasis, and also secretion after stimulation with TNFα, an allergen (cinnamaldehyde), or an irritant (SDS) were assessed. We found that proinflammatory IL-18 and chemokines CCL2, CCL20, and CXCL12, all involved in LC migration, were predominantly secreted by skin as compared to gingiva. Furthermore, CCL27 was predominantly secreted by skin whereas CCL28 was predominantly secreted by gingiva. In contrast, general inflammatory cytokines IL-6 and CXCL8 were secreted similarly by skin and gingiva. These results indicate that the cytokines and chemokines triggering innate immunity and LC migration are different in skin and gingiva. This differential regulation should be figured into novel therapy or vaccination strategies in the context of skin versus mucosa.

MUTZ-3 Langerhans Cell maturation and CXCL12 independent migration in reconstructed human gingiva

“…This, together with the finding that anti-CXCL12 was unable to block migration, indicates that an as yet unknown chemokine / receptor pair is responsible for LC epithelium-to-LP migration in oral gingiva after allergen exposure. Indeed recently, we have shown that GE (without LC), topically exposed to an allergen or an irritant, secrete negligible amounts of key cytokines and chemokines (IL-18, CCL2, CCL20, CXCL12) involved in LC migration compared to skin, whereas the general inflammatory cytokine CXCL8 was secreted at similar levels by SE and GE (Kosten et al, 2015a). These results further support our current findings that the cytokines and chemokines triggering innate immunity and LC migration are very different in skin and gingiva.…”

“…Pro-inflammatory cytokines (e.g., TNFα, IL-α, IL-18) are rapidly released by epidermal cells and trigger the secretion of many chemokines from cells residing in the dermis, thus initiating the inflammatory response (Kosten et al, 2015a). One of these chemokines is CXCL12, which is secreted by dermal fibroblasts (Ouwehand et al, 2008).…”

“…Indeed, in the past we have shown in skin equivalents with integrated Langerhans Cells (SE-LC) that upon allergen exposure MUTZ-3 LC mature and migrate in a CXCL12 dependent manner from the epidermis to the dermis, whereas upon irritant exposure MUTZ-3 LC migrate in a CCL5 dependent manner and undergo an IL-10 dependent phenotypic switch into a macrophage-like cell in the dermis, closely mimicking our observations in excised skin (Kosten et al, 2015b;Ouwehand et al, 2008Ouwehand et al, , 2011b). Recently, we described a full thickness oral gingiva equivalent (GE) consisting of a reconstructed epithelium on a fibroblast populated collagen hydrogel (lamina propria) and shown that the GE secretes negligible amounts of key chemokines involved in LC migration in skin (Kosten et al, 2015a). In this study we have incorporated MUTZ-3 LC into the epithelium of this GE (GE-LC).…”

Comparison of advanced therapy medicinal product gingiva and skin substitutes and their in vitro wound healing potentials

“…Both chemokines are lymphocyte chemo‐attractants (Morales et al, 1999) and CCL28 has high homology with CCL27 (Wang et al, 2000). Recently we have shown in another GS model (reconstructed epithelium on a fibroblast populated collagen hydrogel) that gingiva can indeed secrete CCL27 and that it is also inducible with tumour necrosis factor‐α, albeit to a much lower extent than in skin equivalents (Kosten, Buskermolen, Spiekstra, de Gruijl, & Gibbs, 2015). The reason why CCL28 was undetectable is currently unknown, but it is possible that it is directly internalized by other cells in the vicinity, such as fibroblasts.…”

Comparative phenotypic and functional analysis of migratory dendritic cell subsets from human oral mucosa and skin

“…Our findings indicate that gingival LC in contrast migrate to the lamina propria in a CXCR4/CXCL12 independent fashion. In keeping with this, researchers found that CXCL12 was not secreted by gingival fibroblasts, not even after their activation [16], and that in gingival equivalents LC migrated to the lamina propria in a CXCL12 independent manner [34]. There are indications that LC in the oral mucosa may not even have to migrate to lymph nodes in order to direct a T cell immune response [35].…”