Role of vitamin D and calcium signaling in wound healing

描述(由申请人提供)： 伤口愈合是生存的关键。这是一个涉及许多不同细胞类型的多步骤过程。在皮肤损伤之后，首先是炎症，与生俱来的免疫反应有助于保护皮肤免受入侵生物的侵袭，并触发炎症反应。其次是真皮和表皮细胞的增殖和迁移，以闭合伤口。最后，重塑和分化使皮肤恢复正常，重建渗透屏障。维生素D和钙信号很可能在这些过程中发挥作用，尽管这在伤口愈合方面的研究很少。毛囊隆起中的干细胞不仅为毛囊的形成提供角质形成细胞，还为创伤后的表皮再上皮化提供角质形成细胞。这些隆起干细胞的功能受VDR的调节。维生素D信号是表皮正常的先天免疫反应所必需的。缺乏维生素D受体(VDR)或缺乏产生VDR关键配体1，25二羟基维生素D3(1，25(OH)2D3)的酶(CYP27B1)的小鼠，在创伤后无法激活其先天免疫反应。维生素D信号对角质形成细胞的增殖和分化也是至关重要的，最终导致通透性屏障的重建。缺乏VDR的小鼠表现出分化标志物的表达减少，损伤后屏障恢复迟缓(磁带剥离)。钙是维生素D信号调节角质形成细胞这些过程的关键参与者。钙和维生素D一样，会诱导负责分化的基因，并限制细胞增殖。钙梯度的重建与损伤后通透性屏障的恢复(胶带剥离)平行。钙敏感受体(CAR)在此起关键作用，其表达受1，25(OH)2D3的刺激。缺乏CAR的小鼠先天免疫反应有缺陷，分化标志物表达减少，损伤后屏障恢复延迟(胶带剥离)。这些观察结果让我们得出了以下假设。维生素D信号通过启动创伤后表皮的初始炎症反应，通过控制角质形成细胞的增殖和迁移以关闭伤口，以及通过刺激角质形成细胞的分化以通过CAR需要的机制来改变通透性屏障来调节伤口的愈合。我们将通过实现以下目标来检验这一假设。1.通过检测角质形成细胞中缺乏VDR的小鼠的天然免疫反应、再上皮化率和分化率，确定创面愈合过程中对VDR的需求。2.确定角质形成细胞在创伤后迁移反应中对VDR的需求。3.确定创伤愈合反应中对CAR的要求。我们预计，我们的发现将导致新的治疗方法，通过这些方法可以加速创伤过程，这一过程对我们的军队和退伍军人非常重要。 公共卫生相关性： 皮肤为环境中威胁生命的力量提供了主要的屏障。破坏这一屏障会导致体液流失，并为感染微生物提供一个入口。不能治愈皮肤伤口可能会导致死亡。因此，至关重要的是，伤口愈合是有效的，同时在愈合过程中保护身体免受必需液体的损失和感染。正常皮肤可以很好地做到这一点。尽管所有生物都需要有效的伤口愈合才能健康，但退伍军人更有可能患有危及这一过程的医疗条件，无论是烧伤、旧创伤，还是糖尿病等内科疾病。维生素D是皮肤这些功能的重要调节者之一。维生素D促进通透性屏障的形成，防止液体流失，以及先天免疫反应，防止感染。该项目将评估维生素D信号的丢失对促进伤口愈合过程的影响。

DESCRIPTION (provided by applicant): Wound healing is essential for survival. This is a multistep processes involving a number of different cell types. In the skin wounding is followed initially by inflammation, with the innate immune response contributing both to protection against invasive organisms and to triggering the inflammatory response. This is followed by proliferation and migration of dermal and epidermal cells to close the wound. Finally remodeling and differentiation restore the skin to normal, reestablishing the permeability barrier. Vitamin D and calcium signaling most likely play a role in these processes, although this has received little study in wound healing. Stem cells in the bulge of the hair follicle provide keratinocytes not only for hair follicle formation but also for the reepithelialization of the epidermis following wounding. The function of these bulge stem cells is regulated by VDR. Vitamin D signaling is necessary for a normal innate immune response in the epidermis. Mice lacking the vitamin D receptor (VDR) or lacking the enzyme (CYP27B1) critical for producing the key ligand for VDR, 1,25 dihydroxyvitamin D3 (1,25(OH)2D3), fail to activate their innate immune response following wounding. Vitamin D signaling is also critical for regulation of keratinocyte proliferation and differentiation, eventuating in the reformation of the permeability barrier. Mice lacking the VDR show decreased expression of differentiation markers and a retarded barrier recovery after wounding (tape stripping). Calcium is a critical participant in the mechanism by which vitamin D signaling regulates these processes in keratinocytes. Calcium like vitamin D induces the genes responsible for differentiation, and limits proliferation. Reestablishment of the calcium gradient parallels the restoration of the permeability barrier after wounding (tape stripping). The calcium sensing receptor (CaR) is critical here, and its expression is stimulated by 1,25(OH)2D3. Mice lacking the CaR have a defective innate immune response, decreased expression of differentiation markers, and delayed recovery of the barrier after wounding (tape stripping). These observations have led us to the following hypothesis. Vitamin D signaling regulates wound healing by enabling the initial inflammatory response of the epidermis to wounding, by controlling the proliferation and migration of keratinocytes to close the wound, and by stimulating the differentiation of the keratinocytes to reform the permeability barrier through mechanisms requiring the CaR. We will test this hypothesis by achieving the following aims. 1. Determine the requirement for VDR in the wound healing process by assessing the innate immune response, the rate of reepithelialization, and the rate of differentiation in mice lacking VDR in their keratinocytes. 2. Determine the requirement for VDR in the migratory response of keratinocytes to wounding. 3. Determine the requirement for CaR in the wound healing response. We anticipate that our findings will lead to new therapies by which the wounding process can be accelerated, a process of great importance for our Military and Veteran populations. PUBLIC HEALTH RELEVANCE: The skin provides the major barrier to the life threatening forces in the environment. Disrupting this barrier leads to loss of bodily fluids and provides a portal for infectious organisms. Failure to heal skin wounds can lead to death. Therefore, it is essential that wound healing be efficient and at the same time protect the body from both losses of essential fluids and infection during the healing process. The normal skin does this quite well. Although all creatures require efficient wound healing for health, Veterans are more likely to have medical conditions that compromise this process, whether it be burns, old trauma, or medical diseases such as diabetes mellitus. Among the important regulators of these functions in skin is vitamin D. Vitamin D facilitates the formation of the permeability barrier, protecting against losses of fluids, and the innate immune response, protecting against infection. This project will evaluate the impact of loss of vitamin D signaling on events that contribute to the wound healing process.