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American Journal of Clinical Dermatology

Published in:

01-06-2002 | Review Article

The Acidic Milieu of the Horny Layer

New Findings on the Physiology and Pathophysiology of Skin pH

Authors: Dr Frank Rippke, Volker Schreiner, Hans-Joachim Schwanitz

Published in: American Journal of Clinical Dermatology | Issue 4/2002

Abstract

The acidic pH of the horny layer, measurable on the skin surface, has long been regarded as a result of exocrine secretion of the skin glands. The ‘acid mantle’ was thought to regulate the bacterial skin flora and to be sensitive primarily to skin cleansing procedures.

In recent years, an increasing number of investigations have been published on the changes in, and constituents and functions of, the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. A central role for the acidic milieu as a regulating factor in stratum corneum homeostasis is now emerging. This has relevance to the integrity of the barrier function, from normal maturation of the stratum corneum lipids through to desquamation. Changes in the pH and the organic factors influencing it appear to play a role, not only in the pathogenesis, prevention and treatment of irritant contact dermatitis, but also of atopic dermatitis and ichthyosis and in wound healing.

On the basis of these findings, a broader concept, exceeding the superficial ‘acid mantle’ theory, has been formulated.

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Schade H., Marchionini A. Der Säuremantel der Haut (nach Gaskettenmessung). Klin Wschr 1928; 7: 12–14CrossRef

Dikstein S., Zlotogorski A. Skin surface hydrogen ion concentration (pH). In: Leveque J.-L., editor. Cutaneous investigation in health and disease. New York: Marcel Dekker, 1989: 59–77

Braun-Falco O., Korting H.C. Der normale pH-Wert der Haut. Hautarzt 1986; 37: 126–129PubMed

Marchionini A., Hausknecht W. Säuremantel der Haut und Bakterienabwehr. Klin Wschr 1938; 17: 663–666CrossRef

Rieger M. The apparent pH of the skin. Cosmet Toiletries 1989; 104: 53–60

Welzel J. pH and ions. In: Berardesca E., Elsner P., Wilhelm K.-P., et al., editors. Bioengineering of the skin: methods and instrumentation. Boca Raton (FL): CRC Press, 1995: 91–93

Mayer W., Neurand K., Bartels T.H. The “acid mantle” of the skin of domesticated animals [in German]. Dtsch Tierärztl Wschr 1991; 98: 167–170

Dikstein S., Zlotogorski A. Measurement of skin pH. Acta Derm Venereol (Stockh) 1994; Suppl. 185: 18–20

Öhman H., Vahlquist A. In vivo studies concerning a pH gradient in human stratum corneum and upper epidermis. Acta Derm Venereol (Stockh) 1994; 74: 375–379

10.

Schäfer H., Redelmeier T.E., editors. Skin barrier. Basel: Karger, 1996: 101–117

11.

Szakall A. über die Eigenschaften, Herkunft und physiologischen Funktionen der die H-Ionenkonzentration bestimmenden Wirkstoffe in der verhornten Epidermis. Arch Klin Exp Dermatol 1955; 201: 331–360PubMed

12.

Locher G. Permeabilitätsprüfung der Haut Ekzemkranker und Hautgesunder für den neuen Indikator Nitrazingelb ‘Geigy’, Modifizierung der Alkaliresistenzprobe, pH-Verlauf in der Tiefe des stratum corneum. Dermatologica 1961; 124: 159–182CrossRef

13.

Moon K.C., Wilhelm K.-P., Maibach H.I. Sequential tape stripping of human stratum corneum: influence on pH, water content, adherence; comparison of young and aged skin [abstract]. J Invest Dermatol 1989; 92: 484

14.

Wilhelm D., Elsner P., Maibach H.I. Standardized trauma (tape stripping) in human vulvar and forearm skin. Acta Derm Venereol (Stockh) 1991; 71: 123–126

15.

Berardesca E., Pirot F., Singh M., et al. Differences in stratum corneum pH gradient when comparing white Caucasian and black African-American skin. Br J Dermatol 1998; 139: 855–857PubMedCrossRef

16.

Vahlquist A. Variations in skin pH during normal and pathological keratinisation. Retinoids 1999; 15: 50–53

17.

Krien P.M., Kermici M. Evidence for the existence of a self-regulated enzymatic process within the human stratum corneum: an unexpected role for urocanic acid. J Invest Dermatol 2000; 115: 414–420PubMedCrossRef

18.

Turner N.G., Cullander C., Guy R.H. Determination of the pH gradient across the stratum corneum. J Invest Dermatol Symp Proc 1998; 3: 110–113

19.

Öhman H., Vahlquist A. The pH gradient over the stratum corneum differs in Xlinked recessive and autosomal dominant ichthyosis: a clue to the molecular origin of the ‘acid skin mantle’? J Invest Dermatol 1998; 111: 674–677PubMedCrossRef

20.

Raab W. Skin cleansing in health and disease. Wien Med Wschr 1990; 141 Suppl. 108: 4–10

21.

Thune P., Nilsen T., Hanstad I.K., et al. The water barrier function of the skin in relation to the water content of stratum corneum, pH and skin lipids. Acta Derm Venereol (Stockh) 1988; 68: 277–283

22.

Bock M., Schwanitz H.J. Prevention of irritant contact dermatitis in hairdressers through topical application of CO2-impregnated water: empirical and experimental studies [in German]. Dermatosen Occup Environ 1999; 47: 53–57

23.

Horii I., Nakayama Y., Obata M., et al. Stratum corneum hydration and amino acid content in xerotic skin. Br J Dermatol 1989; 121: 587–592PubMedCrossRef

24.

Warner R.R., Bush R.D., Ruebusch N.A. Corneocytes undergo systematic changes in element concentrations across the human inner stratum corneum. J Invest Dermatol 1995; 104: 530–536PubMedCrossRef

25.

Fluhr J.W., Kao J., Jain M., et al. Generation of free fatty acids from phospholipids regulates stratum corneum acidification and integrity. J Invest Dermatol 2001; 117: 44–51PubMedCrossRef

26.

Chapman S.J., Walsh A. Membrane-coating granules are acidic organelles which possess proton pumps. J Invest Dermatol 1989; 93: 466–470PubMedCrossRef

27.

Behne M., Oda Y., Holleran W.M., et al. The sodium/hydrogen antiporters (NHE) in epidermal pH regulation [abstract]. J Invest Dermatol 1999; 112: 620

28.

Grayson S., Behne M.J., Man M.-Q., et al. Lamellar body and stratum corneum extracellular acidification: implications for the permeability barrier [abstract]. J Invest Dermatol 1993; 100: 528

29.

Behne M., Oda Y., Murata S., et al. Functional role of the sodium-hydrogen antiporter, NHE1, in the epidermis: pharmacologic and NHE1 null-allele mouse studies [abstract]. J Invest Dermatol 2000; 114: 797CrossRef

30.

Forestier J.P. Les enzymes de l’espace extra-cellulaire du stratum corneum. Int J Cosmet Sci 1992; 14: 47–63PubMedCrossRef

31.

Redoules D., Tarroux R., Perie J. Epidermal enzymes: their role in homeostasis and their relationship with dermatoses. Skin Pharmacol Appl Skin Physiol 1998; 11: 183–192PubMedCrossRef

32.

Watkinson A. Stratum corneum gelatinase: a novel late differentiation, epidermal cystein protease [abstract]. J Invest Dermatol 1998; 110: 539

33.

Freinkel R.K., Traczyk T.N. Lipid composition and acid hydrolase content of lamellar granules of fetal rat epidermis. J Invest Dermatol 1985; 85: 295–298PubMedCrossRef

34.

Mauro T., Holleran W.M., Grayson S., et al. Barrier recovery is impeded at neutral pH, independent of ionic effects: implications for extracellular lipid processing. Arch Dermatol Res 1998; 290: 215–222PubMedCrossRef

35.

Menon G.K., Ghadially R., Williams M.L., et al. Lamellar bodies as delivery systems of hydrolytic enzymes: implications for normal and abnormal desquamation. Br J Dermatol 1992; 126: 337–345PubMedCrossRef

36.

Sondell B., Thornell L.-E., Egelrud T. Evidence that stratum corneum chymotryptic enzyme is transported to the stratum corneum extracellular space via lamellar bodies. J Invest Dermatol 1995; 104: 819–823PubMedCrossRef

37.

Bouwstra J.A., Gooris G.S., Dubbelaar F.E.R., et al. pH, cholesterol sulfate, and fatty acids affect the stratum corneum lipid organization. J Invest Dermatol 1998; 3: 69–74

38.

Friberg S.E. Micelles, microemulsions, liquid crystals, and the structure of stratum corneum lipids. J Soc Cosmet Chem 1990; 41: 155–171

39.

Osborne D.W., Friberg S.E. Role of stratum corneum lipids as moisture retaining agent. J Dispers Sci Technol 1987; 8: 173–179CrossRef

40.

Mauro T., Holleran W.M., Man M.-Q., et al. Extracellular pH controls barrier repair [abstract]. J Invest Dermatol 1995; 104: 687

41.

Schreiner V., Maerker U., Hoppe U. Dependence of barrier repair in human skin on intra- and extracellular pH [abstract]. J Invest Dermatol 1996; 106: 917

42.

Weller R. Nitrite oxide: a newly discovered chemical transmitter in human skin. Br J Dermatol 1997; 137: 665–672PubMedCrossRef

43.

Elias P. Stratum corneum architecture, metabolic activity and interactivity with subjacent cell layers. Exp Dermatol 1996; 5: 191–201PubMedCrossRef

44.

Berardesca E., Distante F., Vignoli G.P., et al. Alpha hydroxyacids modulate stratum corneum barrier function. Br J Dermatol 1997; 137: 934–938PubMedCrossRef

45.

Rawlings A.V., Davies A., Carlomusto M., et al. Effect of lactic acid isomers on keratinocyte ceramide synthesis, stratum corneum lipid levels and stratum corneum barrier function. Arch Dermatol Res 1996; 288: 383–390PubMedCrossRef

46.

Pigatto P.D., Bigardi A.S., Cannistraci C., et al. 10% urea cream (Laceran) for atopic dermatitis: a clinical and laboratory evaluation. J Dermatol Treat 1996; 7: 171–175CrossRef

47.

Fartasch M., Teal J., Menon G.K. Mode of action of glycolic acid on human stratum corneum; ultrastructural and functional evaluation of epidermal barrier. Arch Dermatol Res 1997; 287: 404–409CrossRef

48.

Yosipovitch G., Maibach H.I. Skin surface pH: a protective acid mantle. Cosmet Toiletries 1996; 111: 101–102

49.

Behrendt H., Green M. Skin pH pattern in the newborn infant. Am J Dis Child 1958; 95: 35–41

50.

Visscher M.O., Chatterjee R., Munson K.A., et al. Changes in diapered and nondiapered infant skin over the first month of life. Ped Dermatol 2000; 17: 45–51CrossRef

51.

Yosipovitch G., Maayan-Metzger A., Merlob P., et al. Skin barrier properties in different body areas in neonates. Pediatrics 2000; 106: 105–108PubMedCrossRef

52.

Priestley G.C., McVittie E., Aldridge R.D. Changes in skin pH after use of baby wipes. Ped Dermatol 1996; 13: 14–17CrossRef

53.

Berg R.W., Milligan M.C., Sarbaugh F.C. Association of skin wetness and pH with diaper dermatitis. Ped Dermatol 1994; 11: 18–20CrossRef

54.

Huss-Marp J., Schäfer T., Möhrenschlager M., et al. Non-invasive studies of skin pH, hydration of the stratum corneum, transepidermal water loss, skin sebum content and skin roughness in a group of schoolchildren with healthy skin [in German]. Allergo J 1999; 8: 356–361

55.

Zlotogorski A. Distribution of skin surface pH on the forehead and cheek of adults. Arch Dermatol Res 1987; 279: 398–401PubMedCrossRef

56.

Weber G., Türk G., Molls W. Ist der Säuremantel der Hautoberfläche noch existent? Dtsch Derm 1985; 33: 1275–1281

57.

Seidenari S., Giusti G. Objective assessment of the skin of children affected by atopic dermatitis: a study of pH, capacitance and TEWL in eczematous and clinically uninvolved skin. Acta Derm Venereol (Stockh) 1995; 75: 429–433

58.

Gfatter R., Hackl P., Braun F. Effects of soap and detergents on skin surface pH, stratum corneum hydration and fat content in infants. Dermatology 1997; 195: 258–262PubMedCrossRef

59.

Yosipovitch G., Tur E., Cohen O., et al. Skin surface pH in intertriginous areas in NIDDM patients. Diabetes Care 1993; 16: 560–563PubMedCrossRef

60.

Yosipovitch G., Tur E., Morduchowitz G., et al. Skin surface pH, moisture, and pruritus in haemodialysis patients. Nephrol Dial Transplant 1993; 8: 1129–1132PubMed

61.

Laufer A., Dikstein S. Objective measurement and self-assessment of skin-care treatments. Cosmet Toiletries 1996; 111: 91–98

62.

Wilhelm K.-P., Cua A.B., Maibach H.I. Skin aging: effect on transepidermal water loss, stratum corneum hydration, skin surface pH, and casual sebum content. Arch Dermatol 1991; 127: 1806–1809PubMedCrossRef

63.

Jacobson T.M., Ümit Yüksel K., Geesin J.C., et al. Effects of aging and xerosis on the amino acid composition of human skin. J Invest Dermatol 1990; 95: 296–300PubMedCrossRef

64.

Tezuka T., Qing J., Saheki M., et al. Terminal differentiation of facial epidermis of the aged: immunhistochemical studies. Dermatology 1994; 188: 21–24PubMedCrossRef

65.

Imokawa G., Abe A., Jin K., et al. Decreased level of ceramides in stratum corneum of atopic dermatitis: an etiological factor in atopic dry skin? J Invest Dermatol 1991; 96: 523–526PubMedCrossRef

66.

Jin K., Higaki Y., Takagi Y., et al. Analysis of beta-glucocerebrosidase and ceramidase activities in atopic and aged dry skin. Acta Derm Venereol (Stockh) 1994; 74: 337–340

67.

Schütze S., Jensen J.-M., Krönke M., et al. Reduced acidic and neutral sphingomyelinase activities in the skin of aged mice skin [abstract]. J Invest Dermatol 1997; 108: 619

68.

Förl M., Jensen J.-M., Schütze S., et al. Acidic and neutral sphingomyelinases generating ceramides for the skin barrier in outer and inner epidermal layers of aged mice [abstract]. J Invest Dermatol 1998; 110: 672

69.

Schwindt D.A., Wilhelm K.P., Miller D.L., et al. Cumulative irritation in older and younger skin: a comparison. Acta Derm Venereol (Stockh) 1998; 78: 279–281CrossRef

70.

Meigel W., Sepehrmanesh M. Untersuchung der pflegenden Wirkung und der Verträglichkeit einer Creme/Lotio bei älteren Patienten mit trockenem Hautzustand. Dtsch Derm 1994; 42: 1235–1241

71.

Korting H.C., Lucacs A., Braun-Falco O. Mikrobielle Flora und Geruch der menschlichen Haut. Hautarzt 1988; 39: 564–568PubMed

72.

Lukacs A., Korting H.C. Antitranspirants and deodorants: ingredients and evaluation [in German]. Dermatosen 1989; 37: 53–57

73.

Stenzaly-Achtert S., Schölermann A., Schreiber J., et al. Axillary pH and influence of deodorants. Skin Res Technol 2000; 6: 87–91PubMedCrossRef

74.

Elsner P., Maibach H.I. The effect of prolonged drying on transepidermal water loss, capacitance and pH of human vulvar and forearm skin. Acta Derm Venereol (Stockh) 1990; 70: 105–109

75.

Elsner P., Maibach H.I. The vulva. In: Baran R., Maibach H.I., editors. Textbook of cosmetic dermatology. London: Martin Dunitz, 1998: 331–342

76.

Treffel P., Panisset F., Faivre B., et al. Hydration, transepidermal water loss, pH and skin surface parameters: correlations and variations between dominant and non-dominant forearms. Br J Dermatol 1994; 130: 325–328PubMedCrossRef

77.

Yosipovitch G., Xiong G.L., Haus E., et al. Time-dependent variations of the skin barrier function in humans: transepidermal water loss, stratum corneum hydration, skin surface pH, and skin temperature. J Invest Dermatol 1998; 110: 20–23PubMedCrossRef

78.

Le Fur I., Reinberg A., Lopez S., et al. Analysis of circadian and ultradian rhythms of skin surface properties of face and forearm of healthy women. J Invest Dermatol 2001; 117: 718–724PubMedCrossRef

79.

Surber C., Itin P., Rufli T.H. Skin surface pH after short exposure to model solutions. In: Marks R., Plewig G., editors. The environmental threat to the skin. London: Martin Dunitz, 1992: 277–281

80.

Mücke H., Mohr K.-T., Rümmler A., et al. Untersuchungen über den Haut-pH-Wert der Hand nach Anwendung von Seife, Reinigungs- und Händedesinfektionsmitteln. Pharmazie 1993; 48: 468–469PubMed

81.

Grunewald A.M., Gloor M., Kleesz P. Barrier re-compensation mechanisms. In: Elsner P., Lachapelle J.M., Wahlberg J.E., et al., editors. Prevention of contact dermatitis. Current problems in dermatology, Vol. 25. Basel: Karger, 1996: 206–213

82.

Wulfhorst B. Hardening-effect, I: review and state of the art [in German]. Allergologie 1996; 19: 500–508

83.

Schmid M.-H., Korting H.C. The concept of the acid mantle of the skin: its relevance for the choice of skin cleansers. Dermatology 1995; 191: 276–280PubMedCrossRef

84.

Aly R., Shirley C., Cunico B., et al. Effect of prolonged occlusion on the microbial flora, pH, carbon dioxide and transepidermal water loss on human skin. J Invest Dermatol 1978; 71: 378–381PubMedCrossRef

85.

Hartmann A.A. Effect of occlusion on resident flora, skin-moisture and skin-pH. Arch Dermatol Res 1983; 275: 251–254PubMed

86.

Ghane Y., Heese A., Martus P., et al. Veränderungen von Haut-pH und TEWL infolge Okklusion durch medizinische Einmalhandschuhe [abstract]. Hautarzt 1997; 48 Suppl. 1: S71

87.

Romanelli M., Magliaro A., Schipani E., et al. The effect of occlusion on surface pH in chronic ulcers [abstract]. Exp Dermatol 1997; 6: 263

88.

Epprecht R. Elektrometrische Messungen des pH der Hautoberfläche bei Hautgesunden und Ekzempatienten mit besonderer Berücksichtigung der Säureneutralisation. Dermatologica 1955; 111: 204–223PubMedCrossRef

89.

Schnyder U.W., Gloor M., Taugner M. über die sozialmedizinische Bedeutung von Alkaliresistenz, Alkalineutralisation und Hautoberflächenlipidmenge bei Neurodermitis atopica und Ichthyosis vulgaris. Berufs-Dermatosen 1977; 25: 101–140PubMed

90.

Sparavigna A., Setaro M., Gualandri V. Cutaneous pH in children affected by atopic dermatitis and in healthy children: a multicenter study. Skin Res Technol 1999; 5: 221–227CrossRef

91.

Eberlein-König B., Schäfer T., Huss-Marp J., et al. Skin surface pH, stratum corneum hydration, trans-epidermal water loss and skin roughness related to atopic eczema and skin dryness in a population of primary school children. Acta Derm Venereol 2000; 80: 188–191PubMedCrossRef

92.

Blaich W., Niermann H. Pathophysiologische Untersuchungen bei Neurodermitis. Hautarzt 1957; 8: 243–247PubMed

93.

Schwarz E. Neurodermitis und Hornschicht. Z Hautkr 1977; 52 Suppl. 2: 59–64PubMed

94.

Gloor M. über die Hautoberflächenlipide. Hautarzt 1975; 26: 6–10PubMed

95.

Seguchi T., Chang-Yi C., Kusuda S., et al. Decreased expression of filaggrin in atopic skin. Arch Dermatol Res 1996; 288: 442–446PubMedCrossRef

96.

Fartasch M., Diepgen T.L. The barrier function in atopic dry skin: disturbance of membrane-coating granule exocytosis and formation of epidermal lipids? Acta Derm Venereol (Stockh) 1992; Suppl. 176: 26–31

97.

Sasai-Takedatsu M., Kojima T., Yamamoto A., et al. Reduction of staphylococcus aureus in atopic skin lesions with acid electrolytic water: a new therapeutic strategy for atopic dermatitis. Allergy 1997; 52: 1012–1016PubMedCrossRef

98.

Kubota K., Machida I., Tamura K., et al. Treatment of refractory cases of atopic dermatitis with acidic hot-spring bathing. Acta Derm Venereol (Stockh) 1997; 77: 452–454

99.

Korting H.C., Bau A., Baldauf P. pH-Abhängigkeit des Wachstumsverhaltens von Staphylococcus aureus und Propionibakterium acnes. ärztl Kosmetol 1987; 17: 41–53

100.

Inoue T., Inoue S., Kubota K. Bactericidal activity of manganese and iodide ions against staphylococcus aureus: a possible treatment for acute atopic dermatitis. Acta Derm Venereol 1999; 79: 360–362PubMedCrossRef

101.

McNally N.J., Williams H.C., Phillips D.R., et al. Atopic eczema and domestic water hardness. Lancet 1998; 352: 527–531PubMedCrossRef

102.

Klaschka F. Nachbehandlung ekzematöser Erkrankungen. TW Dermatologie 1992; 22: 397–398

103.

Schöne D., Borelli S., Rippke F., et al. High-potency sunscreens for children: importance in atopic dermatitis [in German]. Z Hautkr 1994; 69: 308–313

104.

Bielfeldt S., Wehmeyer A., Rippke F., et al. Efficacy of a new hand care system (cleansing oil and cream) in a model of irritation and in atopic hand eczema [in German]. Dermatosen Occup Environ 1998; 46: 159–165

105.

Wilhelm K.-P., Maibach H.I. Susceptibility to irritant dermatitis induced by sodium lauryl sulphate. J Am Acad Dermatol 1990; 23: 122–124PubMedCrossRef

106.

Francomano M.A., Mantovani L., Pepe P., et al. Baseline biophysical parameters in subjects with sensitive skin [abstract]. Skin Res Technol 1996; 2: 225

107.

Traupe H. Dermatosen der Windelregion. Hautarzt 1992; 43: 523–533PubMed

108.

Dahlquist I., Fregert S. Skin irritation in newborns. Contact Dermatitis 1979; 5: 336–337PubMedCrossRef

109.

Pena Penabad C., Perez Arellano J.L., Becker E., et al. Differential patterns of filaggrin expression in lamellar ichthyosis. Br J Dermatol 1998; 139: 958–964CrossRef

110.

Küster W., Bohnsack K., Rippke F., et al. Efficacy of urea therapy in children with ichthyosis: a multicenter randomized, placebo-controlled, double-blind, semilateral study. Dermatology 1998; 196: 217–222PubMedCrossRef

111.

Mende B., Böhm I., Bauer R. Therapy of ichthyosis lamellosa in childhood: clear success of therapy with lactic acid [in German]. Z Hautkr 1991; 66: 550–554

112.

Van Scott E.J., Yu R.J. Control of keratinization with a-hydroxy acids and related compounds: topical treatment of ichthyotic disorders. Arch Dermatol 1974; 110: 568–590

113.

Runeman B., Faergemann J., Larkö O. Experimental candida albicans lesions in healthy humans: dependence on skin pH. Acta Derm Venereol 2000; 80: 421–424PubMedCrossRef

114.

Weller R., Hobson R., Ormerod A., et al. Acidified nitrite cream is an effective treatment for tinea pedis [abstract]. Br J Dermatol 1996; 135 Suppl. 47: 21

Title: The Acidic Milieu of the Horny Layer
New Findings on the Physiology and Pathophysiology of Skin pH
Authors: Dr Frank Rippke
Volker Schreiner
Hans-Joachim Schwanitz
Publication date: 01-06-2002
Publisher: Springer International Publishing
Published in: American Journal of Clinical Dermatology / Issue 4/2002
Print ISSN: 1175-0561
Electronic ISSN: 1179-1888
DOI: https://doi.org/10.2165/00128071-200203040-00004

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The Acidic Milieu of the Horny Layer

New Findings on the Physiology and Pathophysiology of Skin pH

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