Pronounced reduction of cutaneous Langerhans cell density in recently diagnosed type 2 diabetes.

Immune-mediated processes have been implicated in the pathogenesis of diabetic polyneuropathy. Langerhans cells (LCs) are the sole dendritic cell type located in the healthy epidermis and exert tolerogenic immune functions. We aimed to determine whether alterations in cutaneous LC density and intraepidermal nerve fiber density (IENFD) are present in patients with recently diagnosed type 2 diabetes. Skin biopsy specimens from the distal leg from 96 type 2 diabetic patients and 75 healthy control subjects were used for quantification of LC density and IENFD. LCs and IENFs were labeled using immunohistochemistry. Nerve conduction studies, quantitative sensory testing, and neurological examination were used to assess peripheral nerve function. LC density was markedly reduced in the diabetic group compared with the control group, but did not correlate with reduced IENFD or peripheral nerve function. Multivariate linear regression analysis revealed a strong association between LC density and whole-body insulin sensitivity in women but not in men with diabetes. Prospective studies should establish whether the pronounced reduction of cutaneous LCs detected in recently diagnosed type 2 diabetes could promote a cutaneous immunogenic imbalance toward inflammation predisposing to polyneuropathy and foot ulcers.