Post-inflammatory hyperpigmentation (PIH) is a hypermelanosis that often occurs secondary to skin irritation or injury, especially in darker skin tones, for which there is currently a lack of effective treatment options. Few preclinical models are available to study PIH. Here, we show that the Yucatan miniature pig consistently develops PIH after skin injuries. Skin wounds were produced on Yucatan pigs by needle punches, full-thickness excisions, or burns. Wound sites were monitored and photographed regularly. Tissue samples were collected after 24 weeks and processed for histology/immunohistochemistry. Skin pigmentation and histologic changes were quantified by computer-assisted image analyses. All injury methods resulted in hyperpigmentation. Melanin content at the histologic level was quantified in the larger (burn and excision) wounds, showing a significant increase compared to uninjured skin. Increased melanin was found for both epidermal and dermal regions. Dermal melanin deposits were primarily clustered around the papillary vasculature, and were associated not with melanocytes but with leukocytes. The Yucatan miniature pig model recapitulates key clinical and histologic features of PIH in humans, including skin hyperpigmentation at both gross and histologic levels, and persistence of dermal melanin subsequent to injury. This model could be used to further our understanding of the etiology of PIH, and for new therapy development.

中文翻译：

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尤卡坦小型猪作为炎症后色素沉着过度的模型

炎症后色素沉着过度（PIH）是一种常继发于皮肤刺激或损伤的黑色素沉着过度症，尤其是在深色肤色中，目前缺乏有效的治疗方案。可用于研究 PIH 的临床前模型很少。在这里，我们发现尤卡坦小型猪在皮肤受伤后始终会出现妊娠高血压综合征。尤卡坦半岛猪的皮肤伤口是通过针刺、全层切除或烧伤造成的。定期监测伤口部位并拍照。24 周后收集组织样本并进行组织学/免疫组织化学处理。通过计算机辅助图像分析对皮肤色素沉着和组织学变化进行量化。所有损伤方法都会导致色素沉着过度。在较大的（烧伤和切除）伤口中对组织学水平的黑色素含量进行了定量，显示与未受伤的皮肤相比显着增加。表皮和真皮区域的黑色素均增加。真皮黑色素沉积物主要聚集在乳头状脉管系统周围，与黑素细胞无关，而是与白细胞相关。尤卡坦小型猪模型概括了人类妊娠高血压综合征的关键临床和组织学特征，包括总体和组织学水平上的皮肤色素沉着过度，以及损伤后真皮黑色素的持续存在。该模型可用于进一步了解 PIH 的病因，并用于新疗法的开发。