https://www.jidonline.org/article/S0022-202X(15)41272-2/pdf

Expression of Calcium-Binding S100 Proteins A4 and A6 in Regions of the Epithelial Sac Associated with the Onset of Hair Follicle Regeneration

Human hair consists of proteins, lipids, water, trace elements and pigments. The composition of the first four of these components is the focus of this Chapter. About two decades ago the emphasis on the proteins of hair was on its amino acid constituents which provided important information on the relative amounts of different functional groups in different types of hair and in different regions of the fiber. However, as a result of advances in the characterization and classification of the different proteins and genes of keratins and keratin associated proteins the focus today is on the proteins themselves. Several important new contributions to the composition of the surface layers of hair and the proteins of the cell membrane complex have been and are continuing and therefore are summarized in this Chapter. The current state of changes in the amino acids, proteins and lipids of hair by morphological region (including KAP and keratin proteins and where they reside), chemical and sunlight damage, diet, puberty and menopause, and other factors have been and are being made and are summarized here. An expanded section on metals in hair, where in the fiber these metals reside and the functional groups that they bind to and their effects on hair chemistry, toxicity and disorders are included.

Chemical Composition of Different Hair Types

The structure, chemistry and physical properties of the cell membrane complex (CMC) of keratin fibers are reviewed, highlighting differences in the three types of CMC. Starting with Rogers' initial description of the CMC in animal hairs, several important developments have occurred that will be described, adding new details to this important structure in mammalian hair fibers. These developments show that essentially all of the covalently bound fatty acids of the beta layers are in the cuticle and exist as monolayers. The beta layers of the cortex are bilayers that are not covalently bonded but are attached by ionic and polar linkages on one side to the cortical cell membranes and on the other side to the delta layer. The delta layer between cortical cells consists of five sublayers; its proteins are clearly different from the delta layer that exists between cuticle cells. The cell membranes of cuticle cells are also markedly different from the cell membranes of cortical cells. Models with supporting evidence are presented for the three different types of cell membrane complex: cuticle-cuticle CMC, cuticle-cortex CMC, and cortex-cortex CMC.

The cell membrane complex: three related but different cellular cohesion components of mammalian hair fibers.

Sunlight, especially ultraviolet (UV) light-induced hair damage is difficult to avoid during daily life. Concerns about the effects of ultraviolet light on hair are emerging recently. These photochemical changes mainly come from damage to hair proteins and melanins. In this study, we performed experiments to find the patterns of morphological and biochemical changes in UV-light-induced damage to hair by scanning and transmission electron microscopy and hair protein analysis. In our results, morphological damage is significant in UVB-irradiated hairs, while biochemical changes are greater in UVA-irradiated hairs.

Comparison of hair shaft damage after UVA and UVB irradiation.

Cosmetic hair treatments have been referred to as 'the pitfall' of hair analysis. However, most cosmetic treatments, when applied to the hair as instructed by the product vendors, do not interfere with analysis, provided such treatments can be identified by the laboratory and the samples analyzed and reported appropriately for the condition of the hair. This paper provides methods for identifying damaged or porous hair samples using digestion rates of hair in dithiothreitol with and without proteinase K, as well as a protein measurement method applied to dithiothreitol-digested samples. Extremely damaged samples may be unsuitable for analysis. Aggressive and extended aqueous washing of hair samples is a proven method for removing or identifying externally derived drug contamination of hair. In addition to this wash procedure, we have developed an alternative wash procedure using 90% ethanol for washing damaged or porous hair. The procedure, like the aqueous wash procedure, requires analysis of the last of five washes to evaluate the effectiveness of the washing procedure. This evaluation, termed the Wash Criterion, is derived from studies of the kinetics of washing of hair samples that have been experimentally contaminated and of hair from drug users. To study decontamination methods, in vitro contaminated drug-negative hair samples were washed by both the aqueous buffer method and a 90% ethanol method. Analysis of cocaine and methamphetamine was by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Porous hair samples from drug users, when washed in 90% ethanol, pass the wash criterion although they may fail the aqueous wash criterion. Those samples that fail both the ethanolic and aqueous wash criterion are not reported as positive for ingestion. Similar ratios of the metabolite amphetamine relative to methamphetamine in the last wash and the hair is an additional criterion for assessing contamination vs. ingestion of methamphetamine.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/dta.1652

Identification and analysis of damaged or porous hair

We previously found that certain hair proteins were soluble by means of a partial extraction method. In this study, we demonstrate that the amount of soluble proteins internally formed in permed and bleached hair, labile proteins, is a useful index for hair damage assessment. Compared to tensile property changes, this index rose in widely dynamic ranges as the time of either permanent waving or bleaching treatments increased. The amount of labile proteins was much larger than that of proteins eluted into perming and bleaching lotions. However, the labile proteins showed electrophoretic profiles similar to those of the eluted proteins. These results suggest that a portion of the stable proteins in normal hair was transformed into labile proteins upon permanent waving and bleaching treatments. Consequently, permed and bleached hair tends to release the resultant labile proteins.

Labile proteins accumulated in damaged hair upon permanent waving and bleaching treatments.

In hair fiber, a cysteine-rich calcium-binding S100A3 protein is segregated in the inner part of the cuticle and postulated to play an important role in the attachment to the adjacent cuticular scale. In this study, elution of S100A3 from hair fiber was examined under various conditions by means of immunoblot analyses. The exposure of hair fiber to permanent waving lotions resulted in recoveries of substantial amounts of S100A3 by elution. Ultraviolet-light radiation and perming also increased the elution of S100A3 even without reductant. The distal part of hair fiber eluted less S100A3, as compared to the proximal section, under reducing conditions. These results suggest that S100A3 is eluted preferentially by daily washing and rinsing, especially from damaged hair. Given the presence of soluble S100A3 in the inner part of cuticle, we propose a new mechanism of hair damage in which the elution of S100A3 plays a major role.

Elution of S100A3 from hair fiber : New model for hair damage emphasizing the loss of S100A3 from cuticle

Because of small fluctuations, it is difficult to evaluate hair damage caused by bleaching using previously utilized hair damage indexes. Application of commercial bleaching products elevates partially extractable labile hair protein amounts in the range of 0.4-1.2 mg/g of hair. Within this range, the level of labile protein fluctuates greatly, depending on the extent of bleaching. In the current study, it was found that the effects of alkaline constituents and various peptides contained in bleaching lotions on hair damage could be evaluated by measuring labile protein amounts without employing harsher bleaching conditions.

Kenji Kizawa

Papers

Labile proteins accumulated in damaged hair upon permanent waving and bleaching treatments.

Elution of S100A3 from hair fiber : New model for hair damage emphasizing the loss of S100A3 from cuticle

Practical use of labile protein as an index of hair damage