EpidermisThe epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. The epidermis is composed of multiple layers of flattened cells that overlie a base layer (stratum basale) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in the basal layer.
Integumentary systemThe integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the skin and its appendages, which act as a physical barrier between the external environment and the internal environment that it serves to protect and maintain the body of the animal. Mainly it is the body's outer skin. The integumentary system includes hair, scales, feathers, hooves, and nails.
Autoimmune diseaseAn autoimmune disease is a condition that results from an anomalous response of the immune system, wherein it mistakenly targets and attacks healthy, functioning parts of the body as if they were foreign organisms. It is estimated that there are more than 80 recognized autoimmune diseases, with recent scientific evidence suggesting the existence of potentially more than 100 distinct conditions. Nearly any body part can be involved. Symptoms of autoimmune diseases can significantly vary, primarily based on the specific type of the disease and the body part that it affects.
Skin floraSkin flora, also called skin microbiota, refers to microbiota (communities of microorganisms) that reside on the skin, typically human skin. Many of them are bacteria of which there are around 1,000 species upon human skin from nineteen phyla. Most are found in the superficial layers of the epidermis and the upper parts of hair follicles. Skin flora is usually non-pathogenic, and either commensal (are not harmful to their host) or mutualistic (offer a benefit).
Dendritic cellA dendritic cell (DC) is an antigen-presenting cell (also known as an accessory cell) of the mammalian immune system. A DC's main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and adaptive immune systems. Dendritic cells are present in tissues that are in contact with the body's external environment, such as the skin (where there is a specialized dendritic cell type called the Langerhans cell), and the inner lining of the nose, lungs, stomach and intestines.
Skin infectionA skin infection is an infection of the skin in humans and other animals, that can also affect the associated soft tissues such as loose connective tissue and mucous membranes. They comprise a category of infections termed skin and skin structure infections (SSSIs), or skin and soft tissue infections (SSTIs), and acute bacterial SSSIs (ABSSSIs). They are distinguished from dermatitis (inflammation of the skin), although skin infections can result in skin inflammation.
KeratinocyteKeratinocytes are the primary type of cell found in the epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the basal layer (stratum basale) of the skin are sometimes referred to as basal keratinocytes. Keratinocytes form a barrier against environmental damage by heat, UV radiation, water loss, pathogenic bacteria, fungi, parasites, and viruses. A number of structural proteins, enzymes, lipids, and antimicrobial peptides contribute to maintain the important barrier function of the skin.
Tumor-infiltrating lymphocytesTumor-infiltrating lymphocytes (TIL) are white blood cells that have left the bloodstream and migrated towards a tumor. They include T cells and B cells and are part of the larger category of ‘tumor-infiltrating immune cells’ which consist of both mononuclear and polymorphonuclear immune cells, (i.e., T cells, B cells, natural killer cells, macrophages, neutrophils, dendritic cells, mast cells, eosinophils, basophils, etc.) in variable proportions. Their abundance varies with tumor type and stage and in some cases relates to disease prognosis.
GranulomaA granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such substances include infectious organisms including bacteria and fungi, as well as other materials such as foreign objects, keratin, and suture fragments. In pathology, a granuloma is an organized collection of macrophages. In medical practice, doctors occasionally use the term granuloma in its more literal meaning: "a small nodule".
Trypsin inhibitorA trypsin inhibitor (TI) is a protein and a type of serine protease inhibitor (serpin) that reduces the biological activity of trypsin by controlling the activation and catalytic reactions of proteins. Trypsin is an enzyme involved in the breakdown of many different proteins, primarily as part of digestion in humans and other animals such as monogastrics and young ruminants. Serpins – including trypsin inhibitors – are irreversible and suicide substrate-like inhibitors.
