Diabetic polyneuropathy (DPN) is a complication of diabetes characterized by pain or lack of peripheral sensation, but the underlying mechanisms are not yet fully understood. Recent evidence showed increased cutaneous macrophage infiltration in patients with type 2 diabetes and painful DPN, and this study aimed to understand whether the same applies to type 1 diabetes.

The study included 104 participants: 26 healthy controls and 78 participants with type 1 diabetes (participants without DPN [n = 24], participants with painless DPN [n = 29], and participants with painful DPN [n = 25]). Two immune cells, dermal IBA1⁺ macrophages and epidermal Langerhans cells (LCs, CD207⁺), were visualized and quantified using immunohistological labeling and stereological counting methods on skin biopsies from the participants. The IBA1⁺ macrophage infiltration, LC number density, LC soma cross-sectional area, and LC processes were measured in this study.

Significant difference in IBA1⁺ macrophage expression was seen between the groups (p = 0.003), with lower expression of IBA1 in participants with DPN. No differences in LC morphologies (LC number density, soma cross-sectional area, and process level) were found between the groups (all p > 0.05). In addition, IBA1⁺ macrophages, but not LCs, correlated with intraepidermal nerve fiber density, Michigan neuropathy symptom inventory, (questionnaire and total score), severity of neuropathy as assessed by the Toronto clinical neuropathy score, and vibration detection threshold in the whole study cohort.

This study showed expressional differences of cutaneous IBA1⁺ macrophages but not LC in participants with type 1 diabetes–induced DPN compared with those in controls. The study suggests that a reduction in macrophages may play a role in the development and progression of autoimmune-induced diabetic neuropathy.

糖尿病性多发性神经病（DPN）是糖尿病的一种并发症，其特征是疼痛或缺乏周围感觉，但其潜在机制尚不完全清楚。最近的证据表明，患有 2 型糖尿病和疼痛性 DPN 的患者皮肤巨噬细胞浸润增加，本研究旨在了解这是否也适用于 1 型糖尿病。

该研究包括 104 名参与者：26 名健康对照者和 78 名 1 型糖尿病参与者（无 DPN 的参与者 [n = 24]、无痛 DPN 的参与者 [n = 29] 和有疼痛 DPN 的参与者 [n = 25]）。使用免疫组织学标记和体视计数方法对参与者的皮肤活检中的两种免疫细胞（真皮 IBA1 ⁺巨噬细胞和表皮朗格汉斯细胞（LC，CD207 ^{+ ））进行可视化和量化。}本研究测量了IBA1 ⁺巨噬细胞浸润、LC 数密度、LC 胞体横截面积和 LC 过程。

各组之间IBA1 ⁺巨噬细胞表达存在显着差异 ( p = 0.003)，DPN 参与者中 IBA1 表达较低。各组之间未发现 LC 形态（LC 数密度、胞体横截面积和过程水平）存在差异（所有p > 0.05）。此外，IBA1 ⁺巨噬细胞（而非 LC）与表皮内神经纤维密度、密歇根神经病症状量表（问卷和总分）、多伦多临床神经病评分评估的神经病严重程度以及整个研究中的振动检测阈值相关队列。

这项研究显示，与对照组相比，1 型糖尿病诱发的 DPN 参与者皮肤 IBA1 ^{+巨噬细胞的表达存在差异，但 LC 没有差异。}该研究表明巨噬细胞的减少可能在自身免疫诱导的糖尿病神经病变的发生和进展中发挥作用。