- Email: [email protected]
Dermocosmetic Aspects of Hair and Scalp
Dermocosmetic Aspects of Hair and Scalp Ralph M. Tru¨eb Department of Dermatology, University Hospital of Zurich, Zurich, Switzerland
Hair cosmetic agents are preparations intended for placing in contact with the hair and scalp, with the purpose of cleansing, promoting attractiveness, altering appearance, and/or protecting them in order to maintain them in good condition. Current shampoo formulations and styling products are tailored to the variations associated with age, gender, hair quality, hair care habit, and specific problems relating to the superficial condition of the scalp. The great amount of variables to be accounted for, some of them contradictory and hard to bring into accord, makes adequate product formulation a challenge and requires continuous research. Recent hair cosmetic developments include topical hair growth stimulants, photoprotectors, and anti-aging compounds. The advances in molecular technology have opened the avenue to the study of the molecular basis of hair growth and its deviations, as well as of the aging process. The discovery of potential pharmacological targets and the development of selective and effective delivery systems following topical application indicate further strategies for maintenance of healthy hair and scalp in the young and old.
Key words: hair anti-aging/hair cosmetic agents/hair growth stimulants/photoprotectors of hair and scalp/ shampoos J Investig Dermatol Symp Proc 10:289 –292, 2005 Hair cosmetic agents are preparations intended for placing in contact with the hair and scalp, with the purpose of cleansing, promoting attractiveness, altering appearance, and/or protecting them in order to maintain them in good condition. Although shampooing has been the most common form of cosmetic hair treatment, primarily aimed at cleansing the hair and scalp, the present-day consumer expects more options. The cosmetic industry has become aware of this, and has become more capable of delivering active dermocosmetic agents that are directed toward meeting this consumer demand.
A correlation of PSS with histological findings has revealed that the presence of PPS could reflect the presence of perifollicular inflammatory infiltrates and fibrosis (Deloche et al, 2004). The implication of microscopic follicular inflammation in the pathogenesis of androgenetic alopeica (AGA) has emerged from several independent studies (Jaworsky et al, 1992; Whiting, 1993; Mahe´ et al, 2000). The term ‘‘microinflammation’’ has been proposed, because the process involves a slow, subtle, and indolent course, in contrast to the inflammatory and destructive process in the classical inflammatory scarring alopecias (Mahe´ et al, 2000). An important question is how the inflammatory reaction pattern is generated around the individual hair follicle. The localization in the upper follicle near the infundibulum suggests that the primary causal event for the triggering of inflammation might occur at this site. Considering the microbial colonization of the follicular infundibulum, one could speculate that microbial toxins or antigens may be involved in the generation of the inflammatory response. Alternatively, keratinocytes themselves may respond to chemical stress from irritants, pollutants, and ultraviolet (UV) irradiation, by producing radical oxygen species, nitric oxide, and releasing pro-inflammatory cytokines. In the case where the causal agents persist, sustained inflammation occurs, together with connective tissue remodeling, where collagenases play a role. Collagenases are suspected to contribute to the tissue changes in perifollicular fibrosis. Finally, permanent hair loss results form irreversible damage to the putative site of follicular stem cells in the ‘‘bulge’’ area of the outer-root sheath in the superficial portion of the hair follicle (Lavker et al, 1993). The preference of this site for the immunologic attack may be related to the fact that, in contrast to the proximal hair
Clinical Approach to Common Hair and Scalp Complaints Antonella Tosti reviewed conditions underlying common hair and scalp complaints, such as hair weathering, dandruff, itchy scalp, greasy scalp, and the ‘‘red scalp syndrome,’’ and further characterized them on the basis of videodermoscopy findings. Epiluminiscence microscopy of the scalp at 10 magnification reveals pathologic conditions of the hair shaft and scalp not readily recognized by the naked eye. Examples are hair diameter diversity, the ‘‘peripilar signs’’ (PPS) around the hair ostia and vascular abnormalities (teleangiectasia) of the scalp. Hair diameter diversity has been identified as a marker for the hair follicle miniaturization process in the course of androgenetic alopecia (de Lacharrie`re et al, 2001). Abbreviation: UV, ultraviolet
Copyright r 2005 by The Society for Investigative Dermatology, Inc.
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follicle, the isthmus, and infundibulum area do not bear any immune privilege (Paus, 1997). The ‘‘red scalp syndrome’’ is an ill-defined condition, characterized by persistent erythema of the scalp that is not otherwise explained through a specific dermatologic condition, such as seborrhoic dermatitis. First described by Thestrup-Pedersen and Hjorth (1987), it has been commented upon in the English language by Moschella (1994), who stated the problem of ‘‘diffuse red scalp disease which can also be itchy and burning. Clinically, there is no scaling, no hair loss, and no scarring. It is non responsive to any therapy including potent topical steroids or anti-seborrhoic therapy.’’ A study of 18 patients with ‘‘red scalp syndrome’’ showed that the scalp redness was associated with AGA in the majority of patients.1 Patients often report associated discomfort of the scalp (trichodynia). In another series of patients complaining of hair loss and trichodynia, the dermatoscopic finding of scalp telangiectasia was found to strongly correlate with the presence of trichodynia (Willimann and Tru¨eb, 2002). An interesting analogy to rosacea exists, in which it was found that patients with the telangiectatic variant respond more frequently with astinging sensation to the topical application of 5% lactic acid on the cheek than patients with the papulopustular type of rosacea or normal controls (Lonne-Rahm et al, 1999). In patients with trichodynia, overexpression of neuropeptide substance P has been found (Ericson et al, 1999), suggesting a connection between sensory or subjective irritation and cutaneous vascular reactivity.
Dermocosmetic Management in Practice for the Maintenance of Healthy Hair and Scalp Ralph Tru¨eb reviewed cosmetic hair treatments and dermocosmetic treatments for dandruff, greasy hair, scalp itch, and hair loss. Although shampoos have primarily been products aimed at cleansing the hair and scalp, the diversity of qualities demanded by the present-day consumer go well beyond this function. Current shampoo formulations are adapted to the variations associated with hair quality, hair care habit, and specific problems related to the superficial condition of the scalp (Bouillon, 1996; Shapiro and Maddin, 1996; Tru¨eb, 2001). Accordingly, a shampoo is composed of up to 30 different ingredients: cleansing agents, additives, conditioning agents, and special care ingredients. Cleansing agents function by weakening the physicochemical adhesive force that binds soil to hair, taking it up and transferring it into the aqueous rinse, and dispersing it and preventing redeposition on the hair fiber. This action is carried out by surfactants, compounds with dual affinity: they are both lipophilic by their hydrocarbon fatty chain, which bonds to greasy soil, and hydrophilic by the polar head group at the end of the fatty chain, which makes them water soluble. Depending on the charge of the polar head group, surfactants are divided into anionics, cationics, amphoterics, and non-ionics. A shampoo comprises a 1 Grimalt R, Lacueva L, Hasmann G, Ferrando J. Red scalp syndrome. Annual Meeting of the European Hair Research Society (EHRS), Barcelona, 2000 Abstract F11: 22, 2000.
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mixture of several surfactants, as a single surfactant cannot adequately ensure all expected cosmetic benefits. Although anionics are the primary-cleansing agents, cationics, amphoterics, and non-ionics are utilized to modify surfactant activity. By virtue of their positive charge, cationics show high affinity for hair fiber that is negatively charged. They impart softness to the hair and ease of combing and reducing flyaway, making them appropriate for the care of weathered hair. Amphoterics form a complex with anionics, reducing the latter’s tendency to adsorb onto proteins. Generally combined with other surfactants in the formulation of mild shampoos, they modulate cleansing efficiency and enhance lathering qualities. Finally, non-ionics are the mildest of all surfactants. Their high level of tolerance by the skin has found application in their combination with anionics or amphoterics for very mild shampoos. Additives that contribute to the stability and comfort of the product include foam stabilizers, thickeners, chelating agents, preservatives, pearlescents, opacifiers, fragrances, and colorants. Conditioning agents are intended to impart softness and gloss, to reduce flyaway, and to enhance disentangling facility. They are particularly beneficial for the care of dry hair and weathered hair. A number of ingredients may be introduced into shampoos, mostly fatty ingredients, hydrolyzed proteins, quaternized cationic derivatives, cationic polymers, and more recently, silicones. By the virtue of their high spreading coefficients, silicones, such as dimethicone, readily spread over the surface of hair forming a thin, uniform, hydrophobic film that increases luster and gloss. The lubricant nature of the film reduces inter-fiber friction, resulting in less need for combing force and thus less damage during grooming. Finally, special care ingredients are aimed at modifying specific problems relating to the superficial condition of the scalp. They include anti-dandruff agents, humefactants, and anti-pruritic agents. The great amount of variables to be accounted for, some of them contradictory and hard to bring into accord, makes adequate product formulation a challenge and requires continuous research, as is reflected by the large number of patents appearing in this field. Constant research to find new formulas is at the root of the progress of shampoo technology. For example, micronization of the anti-dandruff agent zink pyrithione has enhanced its efficacy with shorter contact time. Altogether, test methods have been developed to evaluate the efficacy of hair care products, so consumers are offered reliable products that perform as claimed. This has been achieved by transferring consumers’ perceived attributes into scientifically measurable qualities and correlating these laboratory data with real-life results. Recent dermocosmetic developments include topical hair growth stimulants, photoprotectors of hair and scalp, and anti-aging compounds. The rational basis for the development of topical hair growth stimulants are: effect on androgen metabolism (Kaufman, 1996), effect on sebum production and microbial flora (Pierard et al, 1996), effect on microinflammation and fibrosis (Whiting, 1993), and effect on vascularization and vascular epidermal growth factor (Lachgar et al, 1998).
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Among topical hair growth stimulants, minoxidil is the drug with proven efficacy. It has become mandatory that the efficacy of a dermocosmetic agent that claims to act as a hair growth stimulant is measured by the scientific standards set by the clinical studies performed with topical minoxidil and, more recently, oral finasteride for treatment of AGA (Price, 1999). Certainly, hair growth stimulants incorporated into shampoos do not have any impact on hair growth because of short contact time and water dilution. Alternatively, the mechanics of taking care of thinned hair are underrated: the first thing to recommend is to shampoo hair frequently with an appropriate shampoo that will leave the hair fluffy and give the illusion of thicker hair. Aging affects the hair follicle with a decrease of melanocyte function and of hair production (Tobin and Paus, 2001; van Neste and Tobin, 2004). The scalp is subject to both intrinsic or physiologic aging, and extrinsic aging because of external factors. Intrinsic factors are related to individual genetic and epigenetic mechanisms with interindividual variations. Prototypes are AGA (Tru¨eb, 2002), and familial premature graying. Extrinsic factors include UVR (Tru¨eb, 2003b), pollution, smoking (Tru¨eb, 2003a), nutrition, and lifestyle. Experimental evidence supports the hypothesis that oxidative stress plays a role in premature aging. Besides hair conditioners and humefactants for the care of the hair shaft, topical anti-aging compounds would thus include photoprotectors and antioxidants. Others of interest are green tea polyphenols, phytoestrogens, melatonin (Bangha et al, 1996; Fischer et al, 2001), and as yet unidentified substances from TCM and Ayurveda. With respect to photoprotection, hair dyes provide protection of the hair shaft (Pande et al, 2001), and topically applied chemicals that act as UV protectors are under research. Cinnamidpropyltrimonium chloride, a quaternized UV absorber delivered in shampoos, has both UV protective and conditional benefits (Gao and Bedell, 2001). Solid lipid nanoparticles as carriers of UV blockers are under current investigation (Wissing and Muller, 2001). Antioxidants, such as ascorbic acid and tocopherol acetate, protect fatty shampoo ingredients, but not the scalp and hair from oxidation.
Research Activities, Innovations, and Future Outlooks in Hair Care Bruno Bernard gave an overview of current research activities and innovation in hair care, as well as future outlooks in hair research. Current research activities are focused at deciphering the molecular mechanisms involved in the control of the different phases of the hair cycle, and the transition from one phase to another. To date, progress has been achieved in the understanding of the signals involved in the primary organogenesis of the hair follicle. It is not certain, however, whether it may give clues to manipulate telogen–anagen transition. The localization of putative stem cells in the ‘‘bulge’’ area of the outer-root sheath in the superficial portion of the hair follicle (Cotsarelis et al, 1990) from where the follicle is cyclically renewed is also actively ongoing with the identification of specific markers, future tools to isolate and manipulate these cells. Meanwhile,
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molecular characterization of the hair follicle compartments has still not been completely achieved, and subtle subcompartmentalization of basal membrane, connective tissue sheath versus dermal papilla, outer hair root sheath, inner hair root sheath, and hair fiber is being revealed. The complexity of the hair follicle composition probably explains the paucity of recognized active molecules at controlling hair growth and hair cycling, and new avenues are being investigated, i.e., through genomics and proteomics. Even though considerable data will be generated, however, it will probably take a while before pertinent information will be extracted from them. Moreover, as the immediate vascular, nervous, and dermal environment of the hair follicle also plays a very likely major role in its biology, it will have to be taken into consideration more thoroughly. Furthermore, hair pigmentation and the graying process are thoroughly being studied, and new insights are being obtained with respect to the role of absolute melanocyte number, and the melanogenesis pathway that operates in the hair follicle melanocyte (Commo et al, 2004). Although graying is understood as a loss of pigment in the shaft, its cellular and molecular origins are incompletely understood (Tobin and Paus, 2001; van Neste and Tobin, 2004). The color of hair mainly relies on the presence or absence of melanin pigment. Melanin is formed in melanosomes, produced by melanocytes, and is the product of a complex biochemical pathway (melanogenesis), with tyrosinase being the rate-limiting enzyme. It has been shown that gray hair has undergone a marked reduction in melanogenically active melanocytes in the hair follicle (Commo et al, 2004). The net effect of this reduction is that fewer melanosomes are incorporated into cortical keratinocytes. In addition, there appears to be a defect of melanosome transfer. This defect is further corroborated by the observation of melanin debris in and around the graying hair bulb. This anomaly is because of either defective melanosomal transfer to cortical keratinocytes or melanin incontinence from melanocyte degeneration. Eventually, no melanogenic melanocytes remain in the hair bulb. This decrease of melanin synthesis is associated with a decrease in tyrosinase activity. Ultrastructural studies have shown that the remaining melanocytes not only contain fewer melanosomes, but the residual melanosomes may be packaged within autophagolysosomes. This removal of melanosomes into autophagolysosomes suggests that they are defective, possibly with reactive melanin metabolites. This interpretation is supported by the observation that melanocytes in graying hair bulbs are frequently highly vacuolated, a common cellular response to increased oxidative stress. The extraordinary melanogenic activity of pigmented bulbar melanocytes, continuing for up to 10 y in some hair follicles, is likely to generate large amounts of reactive oxygen species via the hydroxylation of tyrosine and the oxidation of DOPA to melanin. If not adequately removed by efficient antioxidant system, an accumulation of these reactive oxidative species will generate significant oxidative stress. It is possible that the antioxidant system may become impaired with age, leading to damage to the melanocyte itself from its own melanogenesis-related oxidative stress. As mutations occur at a higher rate in tissue exposed to high levels of oxidative stress, and these accumulate with age, the induction of
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replicative senescence is likely to be an important protective mechanism against cell transformation. Finally, there is an increasing interest in the hair follicular route for delivery of active compounds affecting the hair. Current research activities focus on topical liposome targeting for melanins, genes, and proteins selectively to hair follicles for therapeutic and cosmetic modification of hair (Hoffman, 1998). For example, topical liposome selective delivery to hair follicles has demonstrated the ability to color hair with melanin. The discovery of potential targets and the development of both selective and effective delivery systems following topical application (Li and Hoffman, 1995) indicate further rational strategies for maintenance of healthy hair and scalp in the young and old.
DOI: 10.1111/j.1087-0024.2005.10118.x Manuscript received September 20, 2004; revised November 22, 2004; accepted for publication December 2, 2004 Address correspondence to: Prof. Dr Ralph M. Tru¨eb, Department of Dermatology, University Hospital of Zurich, Gloriastr. 31, CH-8091 Zurich, Switzerland. Email: [email protected]
References Bangha E, Elsner P, Kistler GS: Suppression of UV-induced erythema by topical treatment with melatonin (N-acetyl-5-methoxytryptamine). Arch Dermatol Res 288:522–526, 1996 Bouillon C: Shampoos. Clin Dermatol 14:113–121, 1996 Commo S, Gaillard O, Bernard BA: Human hair graying is linked to a specific depletion of hair follicle melanocytes affecting both the bulb and the outer root sheath. Br J Dermatol 150:435–443, 2004 Cotsarelis G, Sun TT, Lavker RM: Label-retaining cells reside in the bulge area of pilosebaceous unit: Implications for follicular stem cells, hair cycle, and skin carcinogenesis. Cell 61:1329–1337, 1990 de Lacharrie`re O, Deloche C, Misciali C, et al: Hair diameter diversity: A clinical sign reflecting the follicle miniaturization. Arch Dermatol 137:641–646, 2001 Deloche C, de Lacharrie`re O, Misciali C, et al: Histological features of peripilar signs associated with androgenetic alopecia. Arch Dermatol Res 295:422–428, 2004 Ericson M, Gabrielson A, Worel S, et al: Substance P (SP) in innervated and noninnervated blood vessels in the skin of patients with symptomatic scalp. Exp Dermatol 8:344–345, 1999 Fischer TW, Scholz G, Knoll B, et al: Melatonin reduces UV-induced reactive oxygen species in a dose-dependent manner in IL-3-stimulated leukocytes. J Pineal Res 31:39–45, 2001
Gao T, Bedell A: Ultraviolet damage on natural gray hair and ist photoprotection. J Cosmet Sci 52:103–118, 2001 Hoffman RM: Topical liposome targeting of dyes, melanins, genes, and proteins electively to hair follicles. J Drug Target 5:67–74, 1998 Jaworsky C, Kligman AM, Murphy GF: Characterisation of inflammatory infiltrates in male pattern alopecia: Implication for pathogenesis. Br J Dermatol 127:239–246, 1992 Kaufman KD: Androgen metabolism as it affects hair growth in androgenetic alopecia. Dermatol Clin 14:697–711, 1996 Lachgar S, Charveron M, Gall Y, Bonafe JL: Minoxidil upregulates the expression of vascular endothelial growth factor in human hair dermal papilla cells. Br J Dermatol 138:407–411, 1998 Lavker RM, Miller S, Wilson C, Cotsarelis G, Wei ZG, Yang JS, Sun TT: Hair follicle stem cells: Their location, role in hair cycle, and involvement in skin tumor formation. J Invest Dermatol 101:16S–26S, 1993 Li L, Hoffman RM: The feasibility of targeted selective gene therapy on the hair follicle. Nat Med 1:705–706, 1995 Lonne-Rahm SB, Fischer T, Berg M: Stinging rosacea. Acta Derm Venereol 79:460–461, 1999 Mahe´ YF, Michelet JF, Billoni N, et al: Androgenetic alopecia and microinflammation. Int J Dermatol 39:576–584, 2000 Moschella SL: Written personal communication. August 14, 1994. In: Bernhard JD (ed). Itch. Mechanisms and Management of Pruritus. New York, NY: McGraw-Hill, 1994; p 51 Pande CM, Albrecht L, Yang B: Hair photoprotection by dyes. J Cosmet Sci 52:377–389, 2001 Paus R: Immunology of the hair follicle. In: Bos JD (ed). Skin Immune System. Cutaneous Immunology and Clinical Immunodermatology. Boca Raton, FL: CRC Press, 1997 Pierard GE, Pierard-Franchimont C, Nikkels-Tassoudji N, et al: Improvement in the inflammatory aspect of androgenetic alopecia. A pilot study with an antimicrobial lotion. J Dermatol Treat 7:153–157, 1996 Price VH: Treatment of hair loss. N Engl J Med 341:964–973, 1999 Shapiro J, Maddin S: Medicated shampoos. Clin Dermatol 14:123–128, 1996 Thestrup-Pedersen K, Hjorth N: Rod skalp. En ikke tidligere beskrevet harbundssygdom? Ugeskr Laeger 149:2141–2142, 1987 Tobin DJ, Paus R: Graying: Gerontobiology of the hair follicle pigmentary unit. Exp Gerontol 36:29–54, 2001 Tru¨eb RM: Molecular mechanisms of androgenetic alopecia. Exp Gerontol 37:981–990, 2002 Tru¨eb RM: Association between smoking and hair loss: Another opportunity for health education against smoking? Dermatology 206:189–191, 2003a Tru¨eb RM: Is androgenetic alopecia a photoaggravated dermatosis? Dermatology 207:343–348, 2003b Tru¨eb RM, Swiss Trichology Study Group: The value of hair cosmetics and pharmaceuticals. Dermatology 202:275–282, 2001 van Neste D, Tobin DJ: Hair cycle and hair pigmentation: Dynamic interactions and changes associated with aging. Micron 35:193–200, 2004 Whiting DA: Diagnostic and predictive value of horizontal sections of scalp biopsy specimens in male pattern androgenetic alopecia. J Am Acad Dermatol 28:755–763, 1993 Willimann B, Tru¨eb RM: Hair pain (trichodynia): Frequency and relationship to hair loss and patient gender. Dermatology 205:374–377, 2002 Wissing SA, Muller RH: Solid lipid nanoparticles (SLN)—a novel carrier for UV blockers. Pharmazie 56:783–786, 2001
Hair cosmetic agents are preparations intended for placing in contact with the hair and scalp, with the purpose of cleansing, promoting attractiveness, altering appearance, and/or protecting them in order to maintain them in good condition. Current shampoo formulations and styling products are tailored to the variations associated with age, gender, hair quality, hair care habit, and specific problems relating to the superficial condition of the scalp. The great amount of variables to be accounted for, some of them contradictory and hard to bring into accord, makes adequate product formulation a challenge and requires continuous research. Recent hair cosmetic developments include topical hair growth stimulants, photoprotectors, and anti-aging compounds. The advances in molecular technology have opened the avenue to the study of the molecular basis of hair growth and its deviations, as well as of the aging process. The discovery of potential pharmacological targets and the development of selective and effective delivery systems following topical application indicate further strategies for maintenance of healthy hair and scalp in the young and old.
Key words: hair anti-aging/hair cosmetic agents/hair growth stimulants/photoprotectors of hair and scalp/ shampoos J Investig Dermatol Symp Proc 10:289 –292, 2005 Hair cosmetic agents are preparations intended for placing in contact with the hair and scalp, with the purpose of cleansing, promoting attractiveness, altering appearance, and/or protecting them in order to maintain them in good condition. Although shampooing has been the most common form of cosmetic hair treatment, primarily aimed at cleansing the hair and scalp, the present-day consumer expects more options. The cosmetic industry has become aware of this, and has become more capable of delivering active dermocosmetic agents that are directed toward meeting this consumer demand.
A correlation of PSS with histological findings has revealed that the presence of PPS could reflect the presence of perifollicular inflammatory infiltrates and fibrosis (Deloche et al, 2004). The implication of microscopic follicular inflammation in the pathogenesis of androgenetic alopeica (AGA) has emerged from several independent studies (Jaworsky et al, 1992; Whiting, 1993; Mahe´ et al, 2000). The term ‘‘microinflammation’’ has been proposed, because the process involves a slow, subtle, and indolent course, in contrast to the inflammatory and destructive process in the classical inflammatory scarring alopecias (Mahe´ et al, 2000). An important question is how the inflammatory reaction pattern is generated around the individual hair follicle. The localization in the upper follicle near the infundibulum suggests that the primary causal event for the triggering of inflammation might occur at this site. Considering the microbial colonization of the follicular infundibulum, one could speculate that microbial toxins or antigens may be involved in the generation of the inflammatory response. Alternatively, keratinocytes themselves may respond to chemical stress from irritants, pollutants, and ultraviolet (UV) irradiation, by producing radical oxygen species, nitric oxide, and releasing pro-inflammatory cytokines. In the case where the causal agents persist, sustained inflammation occurs, together with connective tissue remodeling, where collagenases play a role. Collagenases are suspected to contribute to the tissue changes in perifollicular fibrosis. Finally, permanent hair loss results form irreversible damage to the putative site of follicular stem cells in the ‘‘bulge’’ area of the outer-root sheath in the superficial portion of the hair follicle (Lavker et al, 1993). The preference of this site for the immunologic attack may be related to the fact that, in contrast to the proximal hair
Clinical Approach to Common Hair and Scalp Complaints Antonella Tosti reviewed conditions underlying common hair and scalp complaints, such as hair weathering, dandruff, itchy scalp, greasy scalp, and the ‘‘red scalp syndrome,’’ and further characterized them on the basis of videodermoscopy findings. Epiluminiscence microscopy of the scalp at 10 magnification reveals pathologic conditions of the hair shaft and scalp not readily recognized by the naked eye. Examples are hair diameter diversity, the ‘‘peripilar signs’’ (PPS) around the hair ostia and vascular abnormalities (teleangiectasia) of the scalp. Hair diameter diversity has been identified as a marker for the hair follicle miniaturization process in the course of androgenetic alopecia (de Lacharrie`re et al, 2001). Abbreviation: UV, ultraviolet
Copyright r 2005 by The Society for Investigative Dermatology, Inc.
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follicle, the isthmus, and infundibulum area do not bear any immune privilege (Paus, 1997). The ‘‘red scalp syndrome’’ is an ill-defined condition, characterized by persistent erythema of the scalp that is not otherwise explained through a specific dermatologic condition, such as seborrhoic dermatitis. First described by Thestrup-Pedersen and Hjorth (1987), it has been commented upon in the English language by Moschella (1994), who stated the problem of ‘‘diffuse red scalp disease which can also be itchy and burning. Clinically, there is no scaling, no hair loss, and no scarring. It is non responsive to any therapy including potent topical steroids or anti-seborrhoic therapy.’’ A study of 18 patients with ‘‘red scalp syndrome’’ showed that the scalp redness was associated with AGA in the majority of patients.1 Patients often report associated discomfort of the scalp (trichodynia). In another series of patients complaining of hair loss and trichodynia, the dermatoscopic finding of scalp telangiectasia was found to strongly correlate with the presence of trichodynia (Willimann and Tru¨eb, 2002). An interesting analogy to rosacea exists, in which it was found that patients with the telangiectatic variant respond more frequently with astinging sensation to the topical application of 5% lactic acid on the cheek than patients with the papulopustular type of rosacea or normal controls (Lonne-Rahm et al, 1999). In patients with trichodynia, overexpression of neuropeptide substance P has been found (Ericson et al, 1999), suggesting a connection between sensory or subjective irritation and cutaneous vascular reactivity.
Dermocosmetic Management in Practice for the Maintenance of Healthy Hair and Scalp Ralph Tru¨eb reviewed cosmetic hair treatments and dermocosmetic treatments for dandruff, greasy hair, scalp itch, and hair loss. Although shampoos have primarily been products aimed at cleansing the hair and scalp, the diversity of qualities demanded by the present-day consumer go well beyond this function. Current shampoo formulations are adapted to the variations associated with hair quality, hair care habit, and specific problems related to the superficial condition of the scalp (Bouillon, 1996; Shapiro and Maddin, 1996; Tru¨eb, 2001). Accordingly, a shampoo is composed of up to 30 different ingredients: cleansing agents, additives, conditioning agents, and special care ingredients. Cleansing agents function by weakening the physicochemical adhesive force that binds soil to hair, taking it up and transferring it into the aqueous rinse, and dispersing it and preventing redeposition on the hair fiber. This action is carried out by surfactants, compounds with dual affinity: they are both lipophilic by their hydrocarbon fatty chain, which bonds to greasy soil, and hydrophilic by the polar head group at the end of the fatty chain, which makes them water soluble. Depending on the charge of the polar head group, surfactants are divided into anionics, cationics, amphoterics, and non-ionics. A shampoo comprises a 1 Grimalt R, Lacueva L, Hasmann G, Ferrando J. Red scalp syndrome. Annual Meeting of the European Hair Research Society (EHRS), Barcelona, 2000 Abstract F11: 22, 2000.
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mixture of several surfactants, as a single surfactant cannot adequately ensure all expected cosmetic benefits. Although anionics are the primary-cleansing agents, cationics, amphoterics, and non-ionics are utilized to modify surfactant activity. By virtue of their positive charge, cationics show high affinity for hair fiber that is negatively charged. They impart softness to the hair and ease of combing and reducing flyaway, making them appropriate for the care of weathered hair. Amphoterics form a complex with anionics, reducing the latter’s tendency to adsorb onto proteins. Generally combined with other surfactants in the formulation of mild shampoos, they modulate cleansing efficiency and enhance lathering qualities. Finally, non-ionics are the mildest of all surfactants. Their high level of tolerance by the skin has found application in their combination with anionics or amphoterics for very mild shampoos. Additives that contribute to the stability and comfort of the product include foam stabilizers, thickeners, chelating agents, preservatives, pearlescents, opacifiers, fragrances, and colorants. Conditioning agents are intended to impart softness and gloss, to reduce flyaway, and to enhance disentangling facility. They are particularly beneficial for the care of dry hair and weathered hair. A number of ingredients may be introduced into shampoos, mostly fatty ingredients, hydrolyzed proteins, quaternized cationic derivatives, cationic polymers, and more recently, silicones. By the virtue of their high spreading coefficients, silicones, such as dimethicone, readily spread over the surface of hair forming a thin, uniform, hydrophobic film that increases luster and gloss. The lubricant nature of the film reduces inter-fiber friction, resulting in less need for combing force and thus less damage during grooming. Finally, special care ingredients are aimed at modifying specific problems relating to the superficial condition of the scalp. They include anti-dandruff agents, humefactants, and anti-pruritic agents. The great amount of variables to be accounted for, some of them contradictory and hard to bring into accord, makes adequate product formulation a challenge and requires continuous research, as is reflected by the large number of patents appearing in this field. Constant research to find new formulas is at the root of the progress of shampoo technology. For example, micronization of the anti-dandruff agent zink pyrithione has enhanced its efficacy with shorter contact time. Altogether, test methods have been developed to evaluate the efficacy of hair care products, so consumers are offered reliable products that perform as claimed. This has been achieved by transferring consumers’ perceived attributes into scientifically measurable qualities and correlating these laboratory data with real-life results. Recent dermocosmetic developments include topical hair growth stimulants, photoprotectors of hair and scalp, and anti-aging compounds. The rational basis for the development of topical hair growth stimulants are: effect on androgen metabolism (Kaufman, 1996), effect on sebum production and microbial flora (Pierard et al, 1996), effect on microinflammation and fibrosis (Whiting, 1993), and effect on vascularization and vascular epidermal growth factor (Lachgar et al, 1998).
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Among topical hair growth stimulants, minoxidil is the drug with proven efficacy. It has become mandatory that the efficacy of a dermocosmetic agent that claims to act as a hair growth stimulant is measured by the scientific standards set by the clinical studies performed with topical minoxidil and, more recently, oral finasteride for treatment of AGA (Price, 1999). Certainly, hair growth stimulants incorporated into shampoos do not have any impact on hair growth because of short contact time and water dilution. Alternatively, the mechanics of taking care of thinned hair are underrated: the first thing to recommend is to shampoo hair frequently with an appropriate shampoo that will leave the hair fluffy and give the illusion of thicker hair. Aging affects the hair follicle with a decrease of melanocyte function and of hair production (Tobin and Paus, 2001; van Neste and Tobin, 2004). The scalp is subject to both intrinsic or physiologic aging, and extrinsic aging because of external factors. Intrinsic factors are related to individual genetic and epigenetic mechanisms with interindividual variations. Prototypes are AGA (Tru¨eb, 2002), and familial premature graying. Extrinsic factors include UVR (Tru¨eb, 2003b), pollution, smoking (Tru¨eb, 2003a), nutrition, and lifestyle. Experimental evidence supports the hypothesis that oxidative stress plays a role in premature aging. Besides hair conditioners and humefactants for the care of the hair shaft, topical anti-aging compounds would thus include photoprotectors and antioxidants. Others of interest are green tea polyphenols, phytoestrogens, melatonin (Bangha et al, 1996; Fischer et al, 2001), and as yet unidentified substances from TCM and Ayurveda. With respect to photoprotection, hair dyes provide protection of the hair shaft (Pande et al, 2001), and topically applied chemicals that act as UV protectors are under research. Cinnamidpropyltrimonium chloride, a quaternized UV absorber delivered in shampoos, has both UV protective and conditional benefits (Gao and Bedell, 2001). Solid lipid nanoparticles as carriers of UV blockers are under current investigation (Wissing and Muller, 2001). Antioxidants, such as ascorbic acid and tocopherol acetate, protect fatty shampoo ingredients, but not the scalp and hair from oxidation.
Research Activities, Innovations, and Future Outlooks in Hair Care Bruno Bernard gave an overview of current research activities and innovation in hair care, as well as future outlooks in hair research. Current research activities are focused at deciphering the molecular mechanisms involved in the control of the different phases of the hair cycle, and the transition from one phase to another. To date, progress has been achieved in the understanding of the signals involved in the primary organogenesis of the hair follicle. It is not certain, however, whether it may give clues to manipulate telogen–anagen transition. The localization of putative stem cells in the ‘‘bulge’’ area of the outer-root sheath in the superficial portion of the hair follicle (Cotsarelis et al, 1990) from where the follicle is cyclically renewed is also actively ongoing with the identification of specific markers, future tools to isolate and manipulate these cells. Meanwhile,
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molecular characterization of the hair follicle compartments has still not been completely achieved, and subtle subcompartmentalization of basal membrane, connective tissue sheath versus dermal papilla, outer hair root sheath, inner hair root sheath, and hair fiber is being revealed. The complexity of the hair follicle composition probably explains the paucity of recognized active molecules at controlling hair growth and hair cycling, and new avenues are being investigated, i.e., through genomics and proteomics. Even though considerable data will be generated, however, it will probably take a while before pertinent information will be extracted from them. Moreover, as the immediate vascular, nervous, and dermal environment of the hair follicle also plays a very likely major role in its biology, it will have to be taken into consideration more thoroughly. Furthermore, hair pigmentation and the graying process are thoroughly being studied, and new insights are being obtained with respect to the role of absolute melanocyte number, and the melanogenesis pathway that operates in the hair follicle melanocyte (Commo et al, 2004). Although graying is understood as a loss of pigment in the shaft, its cellular and molecular origins are incompletely understood (Tobin and Paus, 2001; van Neste and Tobin, 2004). The color of hair mainly relies on the presence or absence of melanin pigment. Melanin is formed in melanosomes, produced by melanocytes, and is the product of a complex biochemical pathway (melanogenesis), with tyrosinase being the rate-limiting enzyme. It has been shown that gray hair has undergone a marked reduction in melanogenically active melanocytes in the hair follicle (Commo et al, 2004). The net effect of this reduction is that fewer melanosomes are incorporated into cortical keratinocytes. In addition, there appears to be a defect of melanosome transfer. This defect is further corroborated by the observation of melanin debris in and around the graying hair bulb. This anomaly is because of either defective melanosomal transfer to cortical keratinocytes or melanin incontinence from melanocyte degeneration. Eventually, no melanogenic melanocytes remain in the hair bulb. This decrease of melanin synthesis is associated with a decrease in tyrosinase activity. Ultrastructural studies have shown that the remaining melanocytes not only contain fewer melanosomes, but the residual melanosomes may be packaged within autophagolysosomes. This removal of melanosomes into autophagolysosomes suggests that they are defective, possibly with reactive melanin metabolites. This interpretation is supported by the observation that melanocytes in graying hair bulbs are frequently highly vacuolated, a common cellular response to increased oxidative stress. The extraordinary melanogenic activity of pigmented bulbar melanocytes, continuing for up to 10 y in some hair follicles, is likely to generate large amounts of reactive oxygen species via the hydroxylation of tyrosine and the oxidation of DOPA to melanin. If not adequately removed by efficient antioxidant system, an accumulation of these reactive oxidative species will generate significant oxidative stress. It is possible that the antioxidant system may become impaired with age, leading to damage to the melanocyte itself from its own melanogenesis-related oxidative stress. As mutations occur at a higher rate in tissue exposed to high levels of oxidative stress, and these accumulate with age, the induction of
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replicative senescence is likely to be an important protective mechanism against cell transformation. Finally, there is an increasing interest in the hair follicular route for delivery of active compounds affecting the hair. Current research activities focus on topical liposome targeting for melanins, genes, and proteins selectively to hair follicles for therapeutic and cosmetic modification of hair (Hoffman, 1998). For example, topical liposome selective delivery to hair follicles has demonstrated the ability to color hair with melanin. The discovery of potential targets and the development of both selective and effective delivery systems following topical application (Li and Hoffman, 1995) indicate further rational strategies for maintenance of healthy hair and scalp in the young and old.
DOI: 10.1111/j.1087-0024.2005.10118.x Manuscript received September 20, 2004; revised November 22, 2004; accepted for publication December 2, 2004 Address correspondence to: Prof. Dr Ralph M. Tru¨eb, Department of Dermatology, University Hospital of Zurich, Gloriastr. 31, CH-8091 Zurich, Switzerland. Email: [email protected]
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