Intraepithelial macrophage infiltration is related to a high number of regulatory T cells and promotes a progressive course of HPV-induced vulvar neoplasia

Human papilloma virus (HPV)-induced usual-type vulvar intraepithelial neoplasia (uVIN) is infiltrated by myeloid cells but the type and role of these cells is unclear. We used triple immunofluorescent confocal microscopy to locate, identify and quantify myeloid cells based on their staining pattern for CD14, CD33 and CD163 in a cohort of 43 primary and 20 recurrent uVIN lesions, 21 carcinomas and 26 normal vulvar tissues. The progressive course of uVIN is characterized by an increase in both intraepithelial and stromal mature M1 and M2 macrophages. While the M2 macrophages outnumber M1 macrophages in healthy controls and uVIN, they are matched in number by M1 macrophages in cancer. Importantly, uVIN patients with a dense intraepithelial infiltration with mature CD14+ macrophages (irrespective of M1 or M2 type) displayed approximately a six times higher risk to develop a recurrence and a high number of these cells constituted an independent prognostic factor for recurrence. In addition, a dense intraepithelial CD14+ cell infiltration was associated with high numbers of intraepithelial CD4+ Tregs and low numbers of stromal CD8+TIM3+ T cells. Patients with low numbers of intraepithelial CD14+ cells and high numbers of stromal CD8+TIM3+ cells showed the best recurrence-free survival. These data clearly show the importance of the local immune response in HPV-induced vulvar neoplasia and may be of help in predicting the prognosis of patients or their response to immunotherapy. What's new? The infiltration of myeloid cells in human papillomavirus (HPV)-induced usual-type vulvar intraepithelial neoplasia (uVIN) may influence the uVIN microenvironment and responses to immunotherapy. In the present study, uVIN progression was characterized by increases in intraepithelial and stromal M1 and M2 macrophages and by dense intraepithelial infiltration by CD14+ macrophages. Dense CD14+ macrophage infiltration was associated with a significantly increased risk of recurrence, indicating that it is an independent prognostic factor for disease recurrence. By contrast, best recurrence free survival was associated with sparse CD14+ cell populations and an abundance of stromal CD8+TIM3+ cells.