Centre for Dermatology Research, University of Manchester & NIHR Biomedical Research Centre, Manchester, UK.
Department of Dermatology, Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, Salford, UK.
Int J Cosmet Sci. 2024 Oct;46(5):717-733. doi: 10.1111/ics.12956. Epub 2024 Mar 15.
Dandruff is characterised by the presence of perivascular leukocytes and mild inflammation; however, the immune microenvironment of dandruff-affected scalp skin and the potential changes to the hair follicle's (HF) physiological immune privilege (HF IP) remain unknown. Here, we characterised the HF immune microenvironment and immune privilege status in dandruff-affected scalp skin.
We assessed relevant key parameters in healthy versus dandruff-affected human scalp biopsies using quantitative immunohistomorphometry, laser capture microdissection, and RNA sequencing.
The number of epidermal CD4 and CD8 T cells was increased in lesional dandruff scalp skin, while the number of MHC class II/CD1a Langerhans cells was decreased in the infundibulum. The number of intrafollicular and perifollicular CD4 T cells and CD8 T cells, perifollicular CD68 macrophages, and tryptase mast cells remained unchanged. Interestingly, MHC class Ia and ß2-microglobulin protein expression were significantly increased specifically in the suprabulbar outer root sheath (ORS) compartment of dandruff-associated HFs. RNAseq analysis of laser capture micro-dissected suprabulbar ORS compartment revealed antigen presentation pathway as the top regulated canonical pathway, along with the upregulation of HF-IP genes such as HLA-C, HLA-DP, and TAP1, which are normally down-regulated in healthy HFs. Intrafollicular protein expression of known HF IP guardians (CD200 and α-MSH) and 'danger signals' (MICA and CXCL10) remained unaltered at the IP sites of dandruff lesional HFs compared to non-lesional and healthy HFs. Instead, the expression of macrophage migration inhibiting factor (MIF), another HF IP guardian, was reduced.
Together, this work shows that dandruff is associated with epidermal T-cell infiltration and a weakened HF IP in the suprabulbar ORS of HFs in dandruff lesional scalp.
头皮屑的特征是存在血管周围白细胞和轻度炎症；然而，头皮屑影响的头皮皮肤的免疫微环境以及毛囊（HF）生理免疫特权（HF IP）的潜在变化仍然未知。在这里，我们描述了头皮屑影响的头皮皮肤中 HF 的免疫微环境和免疫特权状态。
我们使用定量免疫组织形态计量学、激光捕获显微切割和 RNA 测序评估了健康与头皮屑影响的人类头皮活检之间的相关关键参数。
在病变的头皮屑头皮中，表皮 CD4 和 CD8 T 细胞的数量增加，而在漏斗部，MHC 类 II/CD1a 朗格汉斯细胞的数量减少。内毛囊和毛囊周围的 CD4 T 细胞和 CD8 T 细胞、毛囊周围的 CD68 巨噬细胞和类胰蛋白酶肥大细胞的数量保持不变。有趣的是，MHC 类 Ia 和β2-微球蛋白蛋白表达在头皮屑相关 HF 的超毛囊外根鞘（ORS）隔室中特异性显著增加。激光捕获微切割超毛囊 ORS 隔室的 RNAseq 分析显示抗原呈递途径是调节最多的经典途径，同时上调 HF-IP 基因，如 HLA-C、HLA-DP 和 TAP1，这些基因在健康 HF 中通常下调。与非病变和健康 HF 相比，已知 HF IP 保护者（CD200 和 α-MSH）和“危险信号”（MICA 和 CXCL10）的内毛囊蛋白表达在头皮屑病变 HF 的 IP 部位保持不变。相反，另一个 HF IP 保护者巨噬细胞迁移抑制因子（MIF）的表达减少。
总之，这项工作表明头皮屑与表皮 T 细胞浸润和 HF 在超毛囊 ORS 中的 IP 减弱有关，在头皮屑病变的头皮中。
