Scalp disorders affect millions of people worldwide, but few ingredients have proven efficacy in treating them, posing a challenge for prescribers.
Human hair is a highly visible feature involved in social signaling and often indicates cultural identity and personal style. High, unique among human skin areas. There are over 100,000 hair follicles (HFs) in the scalp out of a total of 5 million human HFs that are formed during embryogenesis and ensure cyclical hair growth throughout life.
The actual structure of hair follicles on the scalp is very different from what is assumed in primers. The base of the hair follicle (“bulb”) lies 4 mm deep in the skin, where cell proliferation occurs and begins to form fibres. As soon as it is generated, the hair fiber becomes biologically “dead” shortly after leaving the bulbous region and begins its two-week journey to the surface of the scalp. This soft pro-fiber initiates the process of maturation (keratinization) and elongation, eventually leading to the stiffest fibers found after leaving the scalp. Similar to the process of connecting basal epidermal cells. A coordinated series of physicochemical changes stretches and strengthens the hair fiber. Hair growth rate and fiber quality are directly related to intense cellular communication between the dermal papilla, macrophages, keratinocytes, bulges and sebaceous glands. This can be modeled as a mechanical process describing the fibers resulting in physical forces from stiffening and water transport.
Mid-20th century discoveries spawned the field of hair follicle immunology, the study of the hair follicle immune system, and stimulated research into the cutaneous immune system, immune-mediated alopecia, and the mechanisms involved in maintaining immune tolerance. Initial ultrastructural analysis also revealed that most of the normal skin flora resides at the opening of the hair follicle. HFs must be important mediators of immune tolerance to commensal microbes. Indeed, recent discoveries have established HF as an essential portal for immune cells in the skin niche. Over the past decade, hair immunology has expanded to include studies of immune-mediated capillary regeneration by direct manipulation of HFSCs and differentiation of dermal and epidermal wound cells. A new study reveals that T cells and macrophages are the most promiscuous immune regulators of HF regeneration in the hair fiber cycle, injury-induced regeneration, and injury-induced capillary neogenesis. Disruption or exaggeration of this relationship can lead to clinically significant forms of immune-mediated alopecia.
HFs that spread from the skin surface into the subcutaneous tissue, which connect directly to the dermis or sebaceous glands, are called pilosebaceous units and, together with the sweat glands, create a unique hydrophobic niche rich in lipids, making the scalp a highly favorable environment for hair growth. to microbes. Ecologically, sebaceous areas have higher microbial diversity than dry areas, affecting both skin physiology and pathological conditions.
Human sebum is a complex mixture of triglycerides, squalene, cholesterol esters, wax esters, and cholesterol secreted from the sebaceous glands to the scalp. Sebocytes, the major cell type of sebaceous glands (SGs), are found associated with hair follicles or specialized glands. Although all SGs are structurally similar, the nature of the products secreted and the regulation underlying secretion appear to differ among different types of SGs. Sebum release is controlled by sebaceous gland activity, and is reported to be strongly correlated with scalp disorders. In a sense, sebaceous gland activity is directly related to the skin’s immune response.
Recently, the role of the skin microbiome in scalp health has been elucidated through various mechanisms, including regulation of host immune responses and protection from skin pathogens. A well-defined environment is provided by the surface of the scalp thanks to microbes that emerge primarily from the host’s physiological conditions, including sebum content, moisture, pH, topography, transepidermal water loss (TEWL) and hydration level. These physiological parameters may affect the microbiota that inhabit the scalp by affecting the scalp environment.
Sebum is an important source of nutrients for the growth of mold and bacteria. Non-specific lipases produced by Malassezia, a fungus important in cases of scalp disorders, can degrade available triglycerides. remains on the skin. It has long been thought that unsaturated fatty acids penetrate the stratum corneum and lead to barrier disruption.
Disturbances in intercellular lipid levels are associated with many pathological and cosmetic skin problems and are directly related to poor scalp conditions in which the epidermal barrier is disrupted. These changes in lipid content may affect tissue water-holding capacity and reduce corneodesmosome degradation leading to skin barrier dysfunction.
Scalp problems, such as oily scalp, are associated with scalp inflammation that causes erythema, itching, burning, and even a more severe condition of desquamation, leading to disruption of the scalp barrier. While enhancing or repairing, it improves the condition of the scalp and enhances the quality of hair through homeostasis.
Sources of oxidative stress such as natural metabolic oxidants, smoking, ultraviolet light, inflammation, pollutants, and oxidized scalp lipids have a profound effect on the health of the scalp and the hair fibers it produces.
The process of lipid peroxidation has been implicated in several human diseases. Oxidative stress processes negatively affect the skin of the scalp, resulting in poor quality hair fibers originating from the scalp and premature hair loss. For optimum quality and holding power.
Active ingredients derived from algae are used in a variety of cosmetic products due to their many beneficial properties. Algae are rich in metabolites such as polyphenols, pigments, glucosylglycerols, sulfated polysaccharides, uronic acid-rich polysaccharides, and mycosporin-like amino acids (MAAs). Seaweeds have a wide range of biological activities, including antibacterial, antioxidant, anti-inflammatory and immunomodulatory effects. Previous studies have shown that a combination of red and brown seaweed modulates the expression of markers involved in the inflammatory response in fibroblasts, leading to decreased inflammation and inducing downregulation of the expression of markers involved in the inflammatory response. was shown.
Polysaccharides in cosmetics are effective for hydration, and seaweed extracts, which are rich in polysaccharides and polyphenols, are also expected to have various beneficial properties for the skin, such as antioxidants, anti-melanogenesis, and skin anti-aging. increase. Phenolic compounds found in red seaweed scavenge free radicals and also exhibit other properties such as inhibition of tyrosinase.
Scalp disorders affect millions of people worldwide, yet few natural bioactive ingredients have proven activity in treating them. Ingredients that prevent or eliminate, regulate the immune response and excess sebum production, combat oxidative stress and reduce inflammation will increasingly receive the attention of scientists, formulators and brands.
