Origin of langerin (CD207)‐expressing antigen presenting cells in the normal oral mucosa and in oral lichen planus lesions

Abstract

The number of langerin-expressing antigen-presenting cells is higher in oral lichen planus than in normal oral mucosa. However, langerin may be expressed by several functionally different lineages of antigen presenting cells (APCs), and this has important implications for our understanding of the pathogenesis of oral lichen planus. The aim of this study was to determine the origin of the langerin-expressing APCs. To this end, we examined oral mucosal biopsies from healthy persons and patients with oral lichen planus using multicolor immunofluorescence. In normal oral mucosa, a substantial fraction of Langerhans cells expressed Ki-67, indicating that steady-state oral mucosal Langerhans cells are at least partially maintained by self-renewal. In oral lichen planus, the numbers of Langerhans cells were higher but proliferation was not altered, indicating that the higher cell numbers appeared to depend on recruited dendritic cell (DC)-precursors. Moreover, we found a markedly higher number of langerin + APCs within the lamina propria of oral lichen planus lesions. Such cells did not display monocyte-or macrophage markers, but rather showed a phenotype compatible with tissue-elicited IRF4 + cDC2. Detailed understanding of how the oral mucosal APC network is regulated and the functional capacities of the different ontogenies may identify novel treatment targets for oral lichen planus.

ALDH1 immunoexpression in epithelial and stromal cells of oral lichen planus and lesions with lichenoid inflammatory infiltrate

“…Activation of T cells depends on antigen presentation by APCs in the context of MHCII receptors. Dendritic cells, a kind of APC control the strength and quality of T and B cell response and are present in both epithelium and lichenoid infiltrate of OLP ( 24 ).…”

Immunological Aspects of EBV and Oral Mucosa Interactions in Oral Lichen Planus

“…In addition, it was found in a significant density already in the case of reticular oral lichen planus, which is clinically characterized by fewer subjective symptoms compared to erosive oral lichen planus [79]. This increase in LC in OLP was observed not only intraepithelially but also in lamina propria and is associated with enhanced recruitment of dendritic cell precursors [80].…”

“…LCs role in OLP pathogenesis confirms studies of OLP biopsies, finding out that in the submucosa, together with lymphocytes, mature LC and DC accumulate [76,83], and that there is a quantitative increase of immature LCs in antigen perception and demonstrating to T cells, as well as ongoing interactions with T lymphocytes in the subepithelial area [77]. When evaluating the amount of Langerin expression by all APCs in OLP and normal oral mucosa, a significantly higher number of MHCII+ APCs were found in OLP, both in the epithelium and in the lamina propria, compared to the normal oral mucosa [80]. Recent studies show that the immune system regulatory function of LCs is also manifested in the activation and propagation of regulatory T cells (Tregs) [80].…”

“…When evaluating the amount of Langerin expression by all APCs in OLP and normal oral mucosa, a significantly higher number of MHCII+ APCs were found in OLP, both in the epithelium and in the lamina propria, compared to the normal oral mucosa [80]. Recent studies show that the immune system regulatory function of LCs is also manifested in the activation and propagation of regulatory T cells (Tregs) [80]. LCs, as a specialized subset of APC both in the skin and in the oral mucosa, are one of the main players in detecting and capturing antigens on the body's barrier surfaces and initiating an immune response.…”

Avaliação imuno-histoquímica das células dendríticas no lúpus eritematoso oral

“…Nas mucosas em monocamada (intestino) ou pseudoestratificada (pulmões) as DC estão localizadas, essencialmente, na lâmina própria, e são pouco representadas no epitélio (Borgne et al, 2007). Já nas mucosas com epitélio pluriestratificado como a oral, vaginal e a mucosa retal, as DC localizam-se nas camadas epiteliais e no tecido conjuntivo da lâmina própria (Borgne et al, 2007) (cDC2) e subpopulações menores de células apresentadoras de antígenos expressando CD1a ou langerina (Solhaug et al, 2022).…”