Rationale: Epidemiological studies have identified an associate between iron deficiency (ID) and the use of oral contraceptives (CC) and ischemic stroke (IS). To date, however, the underlying mechanism remains poorly understood. Both ID and CC have been demonstrated to upregulate the level and iron-binding ability of Tf (transferrin), with our recent study showing that this upregulation can induce hypercoagulability by potentiating FXIIa/thrombin and blocking antithrombin-coagulation proteases interactions. Objective: To investigate whether Tf mediates IS associated with ID or CC and the underlying mechanisms. Methods and Results: Tf levels were assayed in the plasma of IS patients with a history of ID anemia, ID anemia patients, venous thromboembolism patients using CC, and ID mice, and in the cerebrospinal fluid of some IS patients. Effects of ID and estrogen administration on Tf expression and coagulability and the underlying mechanisms were studied in vivo and in vitro. High levels of Tf and Tf-thrombin/FXIIa complexes were found in patients and ID mice. Both ID and estrogen upregulated Tf through hypoxia and estrogen response elements located in the Tf gene enhancer and promoter regions, respectively. In addition, ID, administration of exogenous Tf or estrogen, and Tf overexpression promoted platelet-based thrombin generation and hypercoagulability and thus aggravated IS. In contrast, anti-Tf antibodies, Tf knockdown, and peptide inhibitors of Tf-thrombin/FXIIa interaction exerted anti-IS effects in vivo. Conclusions: Our findings revealed that certain factors (ie, ID and CC) upregulating Tf are risk factors of thromboembolic diseases decipher a previously unrecognized mechanistic association among ID, CC, and IS and provide a novel strategy for the development of anti-IS medicine by interfering with Tf-thrombin/FXIIa interactions.

Although it is well known that wound healing proceeds incredibly quickly in urodele amphibians, such as newts and salamanders, little is known about skin‐wound healing, and no bioactive/effector substance that contributes to wound healing has been identified from these animals. As a step toward understanding salamander wound healing and skin regeneration, a potential wound‐healing‐promoting peptide (tylotoin; KCVRQNNKRVCK) was identified from salamander skin of Tylototriton verrucosus. It shows comparable wound‐healing‐promoting ability (EC ₅₀ =11.14 μg/ml) with epidermal growth factor (EGF; NSDSECPLSHDGYCLHDGVCMYIEALDKYACNCVVGYIGERCQYRDLKWWELR) in a murine model of full‐thickness dermal wound. Tylotoin directly enhances the motility and proliferation of keratinocytes, vascular endothelial cells, and fibroblasts, resulting in accelerated reepithelialization and granulation tissue formation in the wound site. Tylotoin also promotes the release of transforming growth factor β1 (TGF‐β1) and interleukin 6 (IL‐6), which are essential in the wound healing response. Gene‐encoded tylotoin secreted in salamander skin is possibly an effector molecule for skin wound healing. This study may facilitate understanding of the cellular and molecular events that underlie quick wound healing in salamanders.—Mu, L., Tang, J., Liu, H., Shen, C., Rong, M., Zhang, Z., Lai, R. A potential wound‐healing‐promoting peptide from salamander skin. FASEB J. 28, 3919‐3929 (2014). www.fasebj.org

Studies have shown significantly increased thromboembolic events at high altitude. We recently reported that transferrin could potentiate blood coagulation, but the underlying mechanism for high altitude–related thromboembolism is still poorly understood. Here, we examined the activity and concentration of plasma coagulation factors and transferrin in plasma collected from long-term human residents and short-stay mice exposed to varying altitudes. We found that the activities of thrombin and factor XIIa (FXIIa) along with the concentrations of transferrin were significantly increased in the plasma of humans and mice at high altitudes. Furthermore, both hypoxia (6% O2) and low temperature (0°C), 2 critical high-altitude factors, enhanced hypoxia-inducible factor 1α (HIF-1α) levels to promote the expression of the transferrin gene, whose enhancer region contains HIF-1α binding site, and consequently, to induce hypercoagulability by potentiating thrombin and FXIIa. Importantly, thromboembolic disorders and pathological insults in mouse models induced by both hypoxia and low temperature were ameliorated by transferrin interferences, including transferrin antibody treatment, transferrin downregulation, and the administration of our designed peptides that inhibit the potentiation of transferrin on thrombin and FXIIa. Thus, low temperature and hypoxia upregulated transferrin expression–promoted hypercoagulability. Our data suggest that targeting the transferrin-coagulation pathway is a novel and potentially powerful strategy against thromboembolic events caused by harmful environmental factors under high-altitude conditions.