Hemoglobin in the epidermis

Researchers have shown for the first time that haemoglobin, a protein found in red blood cells where it binds oxygen, is also present in the epidermis, our skin's outermost body tissue. The study, which appears in the Journal of Investigative Dermatology, and published by Elsevier, provides important insights into the properties of our skin's protective external layer.

This research was driven by a curiosity about how the epidermis protects our delicate body from the environment and what unexpected molecules are expressed in the epidermis. Researchers discovered the hemoglobin α protein in keratinocytes of the epidermis and in hair follicles. This unexpected evidence adds a new facet to the understanding of the workings of our skin's defense mechanisms.

Hemoglobin binds gases such as oxygen, carbon dioxide, and nitric oxide, and it is an iron carrier via the heme complex. These properties make epidermal hemoglobin a prime candidate for antioxidant activity and potentially other roles in barrier function.

Professor Amagai concludes: "Our study showed that epidermal hemoglobin was upregulated by oxidative stress and inhibited the production of reactive oxygen species in human keratinocyte cell cultures. Our findings suggest that hemoglobin α protects keratinocytes from oxidative stress derived from external or internal sources such as UV irradiation and impaired mitochondrial function, respectively. Therefore, the expression of hemoglobin by keratinocytes represents an endogenous defense mechanism against skin aging and skin cancer."

Reference: Discovery of hemoglobin in the epidermis sheds new light on our skin's protective properties; Journal of Investigative Dermatology, DOI:10.1016/j.jid.2023.08.008.