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• W2009667054 abstract "Although basal permeability barrier function is established at birth, the higher risk for infections, dermatitis, and percutaneous absorption of toxic agents may indicate incomplete permeability barrier maturation in the early neonatal period. Since stratum corneum (SC) acidification in adults is required for normal permeability barrier homeostasis, and lipid processing occurs via acidic pH dependent enzymes, we hypothesized that, in parallel with the less acidic surface pH, newborn SC would exhibit signs of incomplete barrier formation. Fluorescence lifetime imaging reveals that neonatal rat SC acidification first becomes evident by postnatal day 3, in extracellular “microdomains” at the SC- stratum granulosum (SG) interface, where pH-sensitive lipid processing is known to occur. This localized acidification correlated temporally with efficient processing of secreted lamellar body contents to mature extracellular lamellar bilayers. Since expression of the key acidifying mechanism NHE1 is maximal just prior to birth, and gradually declines over the first postnatal week, subop-timal SC acidification at birth cannot be attributed to insufficient NHE1 expression, but could instead reflect reduced NHE1 activity. Expression of the key lipid processing enzyme, β-glucocerebrosidase (β-GlcCer’ase), develops similar to NHE1, excluding a lack of β-GlcCer’ase protein as rate limiting for efficient lipid processing. These results define a postnatal development consisting of initial acidification in the lower SC followed by outward progression, which is accompanied by formation of mature extracellular lamellar membranes. Thus, full barrier competence appears to require the extension of acidification in microdomains from the SC/SG interface outward toward the skin surface in the immediate postnatal period. Although basal permeability barrier function is established at birth, the higher risk for infections, dermatitis, and percutaneous absorption of toxic agents may indicate incomplete permeability barrier maturation in the early neonatal period. Since stratum corneum (SC) acidification in adults is required for normal permeability barrier homeostasis, and lipid processing occurs via acidic pH dependent enzymes, we hypothesized that, in parallel with the less acidic surface pH, newborn SC would exhibit signs of incomplete barrier formation. Fluorescence lifetime imaging reveals that neonatal rat SC acidification first becomes evident by postnatal day 3, in extracellular “microdomains” at the SC- stratum granulosum (SG) interface, where pH-sensitive lipid processing is known to occur. This localized acidification correlated temporally with efficient processing of secreted lamellar body contents to mature extracellular lamellar bilayers. Since expression of the key acidifying mechanism NHE1 is maximal just prior to birth, and gradually declines over the first postnatal week, subop-timal SC acidification at birth cannot be attributed to insufficient NHE1 expression, but could instead reflect reduced NHE1 activity. Expression of the key lipid processing enzyme, β-glucocerebrosidase (β-GlcCer’ase), develops similar to NHE1, excluding a lack of β-GlcCer’ase protein as rate limiting for efficient lipid processing. These results define a postnatal development consisting of initial acidification in the lower SC followed by outward progression, which is accompanied by formation of mature extracellular lamellar membranes. Thus, full barrier competence appears to require the extension of acidification in microdomains from the SC/SG interface outward toward the skin surface in the immediate postnatal period. β-glucocerebrosidase cultured human kcratinocytes from foreskin free fatty acids fluorescence lifetime imaging microscopy hematoxylin-eosin sodium/ hydrogen antiporter 1 sphingomyelinase phospholipids stratum corneum standard error of the mean stratum granulosum secretory phospholipase A2 Full-term mammalian infants are born with a neutral skin surface pH, which normalizes to acidic values over the first few postnatal days-to-weeks, depending on species. The neutral skin surface pH of human infants was first noted by Taddei, 1935Taddei A. Ricerche, mediante indicatori, sulla relazionc attuale della cute nel neona- to.Riv Ital Ginec. 1935; 18: 496Google Scholar, and Behrendt and Green, 1958Behrendt H. Green M. Skin pH pattern in the newborn infant.AMA Journal of Diseases of Children. 1958; 95: 35-41PubMed Google Scholar detailed the kinetics of development of an acidic surface pH over the first postnatal month (1958). Since the skin surface pH of both full-term and premature infants acidifies rapidly during the first week (Fox et al., 1998Fox C. Nelson D. Wareham J. The timing of skin acidification in very low birth weight infants.J Perinatol. 1998; 18: 272-275PubMed Google Scholar; Visscher et al., 2001Visscher M. Hoath S.B. Conroy E. Wickett R.R. Effect of semipermeable membrane on skin barrier repair following tape stripping.Arch Dermatol Res. 2001; 293: 491-499Crossref PubMed Scopus (68) Google Scholar), the progressive postnatal adaptation of SC pH to ex-utcro conditions occurs independent of fetal age at birth. In adults and neonates, formation and maintenance of the cutaneous permeability barrier requires hydrolytic processing of the relatively polar, secreted lipid mixture of lamellar bodies into their less polar lipid products, a process that is controlled by SC pH (Mauro et al., 1998Mauro T. Hollcran 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: 215-222Crossref PubMed Scopus (234) Google Scholar). Two of the “lysosomal-type” enzymes that are required for this lipid processing, β-glucocerebrosidase (β-GlcCer’ase) and acidic sphingomyelinase (aSM’ase), are cosecrcted with the lipids to the extracellular domains of the lower SC, but both require an acidic milieu for optimal activity (Holleran et al., 1992Holleran W.M. Takagi Y. Imokawa G. Jackson S. Lec J.M. Elias P.M. beta-Glucocereb-rosidase activity in murine epidermis. Characterization and localization in relation to differentiation.J Lipid Res. 1992; 33: 1201-1209PubMed Google Scholar; Jensen et al., 1999Jensen J.M. Schutzc S. Fori M. Kronke M. Proksch E. Roles for tumor necrosis factor receptor p55 and sphingomyelinase in repairing the cutaneous permeability barrier.J Clin Invest. 1999; 104: 1761-1770Crossref PubMed Scopus (164) Google Scholar). Despite normal basal barrier function at birth (Cunico et al., 1977Cunico R.L. Maibach I.I.I. Khan H. Bloom E. Skin barrier properties in the newborn. Transcpidermal water loss and carbon dioxide emission rates.Biol Neonate. 1977; 32: 177-182Crossref PubMed Scopus (54) Google Scholar), even full-term infants’ skin exhibits a greater tendency to develop irritant/allergic contact dermatitis when exposed to alkaline or neutral solutions (Wilhelm and Maibach, 1990Wilhelm K.P. Maibach H.I. Factors predisposing to cutaneous irritation.Dermatol Gin. 1990; 8: 17-22Abstract Full Text PDF PubMed Google Scholar; Berg et al., 1994Berg R.W. Milligan M.C. Sarbaugh F.C. Association of skin wetness and pH with diaper dermatitis.Pediatr Dermatol. 1994; 11: 18-20Crossref PubMed Scopus (152) Google Scholar; Seidenari and Giusti, 1995Seidenari S. Giusti G. Objective assessment of the skin of children affected by atopic dermatitis: A study of pFl, capacitance andTEWL in eczematous and clinically uninvolvcd skin.Acta Dermato-Venereologica. 1995; 75: 429-433PubMed Google Scholar), suggesting that barrier function is not fully mature at birth. During the immediate postnatal period, infant SC simultaneously acidifies, and reduces its susceptibility to irritants, microbes, and xe-nobiotic penetration (Harpin and Rutter, 1983Harpin V.A. Rutter N. Barrier properties of the newborn infant's skin.J Pediatr. 1983; 102: 419-425Abstract Full Text PDF PubMed Scopus (243) Google Scholar; Visscher et al., 2000Visscher M.O. Chatterjee R. Munson K.A. Pickens W.L. Hoath S.B. Changes in diapered and nondiapered infant skin over the first month of life.Pediatr DemMld. 2000; 17: 45-51Google Scholar). Together, these observations suggest that development of a fully—mature permeability barrier is linked to SC acidification. We hypothesized, therefore, that the neutral pH of infants’ skin could delay the formation of mature lipid bilayers leading to optimal barrier function, and that delayed acidification could explain the increased infantile risk for irritant/allergic contact dermatitis, infection, and percutaneous absorption of toxic chemicals. Rats have served as a useful model to examine a range of parameters of the peri- and neonatal adaptation process (Aszterbaum et al., 1992Aszterbaum M. Menon G.K. Fcingold K.R. Williams M.L. Ontogeny of the epidermal barrier to water loss in the rat: Correlation of function with stratum corneum structure and lipid content.Pcdiatr Res. 1992; 31: 308-317Crossref PubMed Scopus (74) Google Scholar; Hoath et al., 1993Hoath S.B. Tanaka R. Boyce S.T. Rate of stratum corneum formation in the perinatal rat.Invest Dermatol. 1993; 100: 400-406Abstract Full Text PDF PubMed Scopus (16) Google Scholar; Wickett et al., 1993Wickett R.R. Mutschelknaus J.L. Hoath S.B. Ontogeny of water sorption-desorption in the perinatal rat.J Invest Dermatol. 1993; 100: 407-411Abstract Full Text PDF PubMed Scopus (30) Google Scholar; Hanley et al., 1997Hanley K. Jiang Y. Holleran W.M. Elias P.M. Williams M.L. Feingold K.R. Glucosyl-ccramidc metabolism is regulated during normal and hormonally stimulated epidermal barrier development in the rat.J Lipid Res. 1997; 38: 576-584PubMed Google Scholar). These studies have shown that the epidermal permeability barrier develops late in gestation, paralleled by increased expression of pH-dependent, lipid-processing enzymes. Yet, the pH of the SC of neonatal rats is neutral, as in humans. Although the rodent model exhibits certain differences from the human neonate, notably the hyperplasticity of neonatal rat epidermis, and the persistence of a periderm for several days post birth (Hoath et al., 1993Hoath S.B. Tanaka R. Boyce S.T. Rate of stratum corneum formation in the perinatal rat.Invest Dermatol. 1993; 100: 400-406Abstract Full Text PDF PubMed Scopus (16) Google Scholar) versus the presence of vernix cascosa at birth in full-term humans (Pickens et al., 2000Pickens W.L. Warner R.R. Boissy Y.L. Boissy R.E. Hoath S.B. Characterization of ver-nix caseosa: Water content, morphology, and elemental analysis.J Invest Dermatol. 2000; 115: 875-881Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar), development of the SC acid mantle occurs postnatally in both species. We therefore used newborn rats to study the adaptation of neonatal skin from the neutral pH, aqueous in-utero environment, to the dry postnatal environment. Specifically, we examined here the spatio-temporal development and changes in SC microdomain distribution of acidity during early postnatal development. Employing our newly developed application, fluorescence lifetime imaging (FLIM) (Hanson et al., 2002Hanson K.M. Behne M.J. Barry N.P. Mauro T.M. Gratton E. Clegg R.M. Two-photon fluorescence lifetime imaging of the skin stratum corneum pH gradient.BiophysJ. 2002; 83: 1682-1690Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar), we first localized the events leading to an acidic SC, and then correlated these changes with parallel, acidity-requiring, lipid processing in the SC interstices that produces a fully competent epidermal permeability barrier. In addition, we assessed the role of the periderm and its dissolution as a possible contributor to neonatal SC acidification. Pregnant sprague-dawley rats were obtained from Charles River Laboratories (Hollister, CA) and fed Purina mouse diet and water ad libitum. Newborn pups were removed individually from the litter, in approximately 24 h intervals following birth. Fetal tissue samples were generated by cesarean section, as described earlier (Aszterbaum et al., 1992Aszterbaum M. Menon G.K. Fcingold K.R. Williams M.L. Ontogeny of the epidermal barrier to water loss in the rat: Correlation of function with stratum corneum structure and lipid content.Pcdiatr Res. 1992; 31: 308-317Crossref PubMed Scopus (74) Google Scholar). 2′,7′-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) was from molecular probes (Eugene, OR). All other chemicals were of analytical grade. All experiments were performed under animal protocols reviewed and approved by the Institutional Animal Care and Use Committee (IACUC) at the VA Medical Center, San Francisco, CA. pH was determined using the lifetime-sensitive fluorescent pH indicator BCECF (Molecular Probes, 100 mM applied in pure ethanol), as reported previously (Behne et al., 2002Behne M.J. Meyer J.W. Hanson K.M. et al.NHE1 regulates the stratum corneum permeability barrier homeostasis. Microenvironmcnt acidification assessed with fluorescence lifetime imaging.J Biol Chem. 2002; 277: 47399-47406Crossref PubMed Scopus (176) Google Scholar; Hanson et al., 2002Hanson K.M. Behne M.J. Barry N.P. Mauro T.M. Gratton E. Clegg R.M. Two-photon fluorescence lifetime imaging of the skin stratum corneum pH gradient.BiophysJ. 2002; 83: 1682-1690Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar). Pups were kept in a 37 °C environment and ambient humidity for the duration of the dye incubation. A biopsy was taken approximately 15 mm following the last dye application, mounted for microscopy, and directly visualized. In brief, two-photon fluorescence lifetime imaging microscopy (FLIM) (Szmacinski and Lakowicz, 1993Szmacinski H. Lakowicz J.R. Optical measurements of pH using fluorescence lift-times and phase- modulation fluorometry.Anal Chem. 1993; 65: 1668-1674Crossref PubMed Scopus (150) Google Scholar; Masters et al., 1997Masters B.R. So P.T. Gratton E. Multiphoton excitation fluorescence microscopy and spectroscopy of in vivo human skin.BiophysJ. 1997; 72: 2405-2412Abstract Full Text PDF PubMed Scopus (442) Google Scholar; Tadrous, 2000Tadrous P.J. Methods for imaging the structure and function of living tissues and cells: 2. Fluorescence lifetime imaging.J Pathol. 2000; 191: 229-234Crossref PubMed Scopus (92) Google Scholar) to determine pH was performed by using a Millenia-pumpcd Tsunami titanium:sapphire laser system (Spectra-Physics) as the two-photon excitation source. Excitation of the sample was achieved by coupling the 820 nm output of the laser through the epifluorcsccnce port of a Zeiss Axiovert microscope. The fluorescence was collected using a Hamamatsu (R3996) photomultiplier placed at the bottom port of the microscope. Scanning mirrors and a 40 × infinity corrected oil objective (Zeiss F Fluar, 1.3 NA) were used to image areas of 107 μm2. Z-slices (1.7 μm per slice) were obtained by adjusting the objective focus with a motorized driver (ASI Multi-Scan 4). Lifetime data were acquired using the frequency-domain method (80 MHz). Fluorescein was used as the reference lifetime standard (τf=4.05 ns, pH 9.5). Data-evaluation and visualization were performed directly with the in-house software SIM-FCS. Fluorescence-intensity images were adjusted to enhance structural features and to visualize dye distribution and penetration. Lifetime-values were converted to pH-values, based on a calibration of BCECF in a series of buffers of different pH. The resulting pH-maps are displayed on the same color-scale to facilitate comparisons. The pH-value distribution within these images is depicted in the corresponding histograms. For some experiments, these histograms were imported into Origin (Origin Laboratory Corporation, Northampton, MA) to form a reconstruction graph of pH values over depth. Individual images were combined using Adobe Illustrator (Adobe Systems Incorporated, San Jose, CA), but no further image processing was performed. Background fluorescence was measured in samples of unstained tissue, treated otherwise identically. Conventional surface pH measurements were performed using a flat glass surface electrode (Mettler-Toledo, Giessen, Germany) with a pH meter (Skin pH Meter PH 900; Courage & Khazaka, Cologne, Germany). Fresh tissue biopsies were directly immersed in formalin, and stored at 4 °C until paraffin embedding. 5μm sections were cut, and routinely H&E stained. Images were taken on a Zeiss Axiovert Microscope. Freshly obtained biopsies from newborn rat skin (taken from the same animals used for FLIM and light microscopy experiments) were fixed directly in modified Karnovsky's fixative, postfixed with reduced osmium tetroxide (OsO4), and then embedded in an Epon-epoxy mixture. For visualization of lipid-enriched, lamellar bilayer structures, some samples were postfixed with ruthenium tetroxide (Ru04). Sections were cut on a Reichcrt Ultracut E microtome, counterstaincd with uranyl acetate and lead citrate, and viewed in a Zeiss 10 CR electron microscope, operated at 60 kV. Fresh biopsies from newborn rats, or from fetal rats obtained by C-section, were formaldehyde fixed, paraffin-embedded, and sectioned (5 μm). For immunolabeling of NHE1, a rabbit polyclonal antibody was used (Chemicon Int., Temecula, CA), which was detected via a FITC-labeled, secondary goat anti rabbit antibody (Capped, Organon Teknika Corp., Durham, NC). Sections were counterstained with propidium iodide (Sigma, St. Louis, MO), and pictures were taken on a Leica TCS-SP confocal microscope. Detection of β-GlcCer’ase was performed similarly, employing a polyclonal antibody from rabbit (gift from Drs Ginns and Sidranski, NIH). Full thickness skin was harvested from newborn rats, and incubated in 10 mM ethylenediaminetetraacetic acid (EDTA) solution for 30 min. The epidermis was subsequently separated by gentle scraping, and membrane fractions (Triton-X100 soluble fraction) prepared. Similarly, membrane fractions were prepared from cultured human keratinocytes, directly immersed in Triton-X100 buffer. The protein contents of individual samples were determined, and gels were loaded with equal amounts per sample and lane. Western immunoblotting was performed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), as described previously (Laemmli, 1970Laemmli U.K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4.Nature. 1970; 227: 680-685Crossref PubMed Scopus (206983) Google Scholar). Following transfer of protein to polyvinylidene difluoride (PVDF) membranes, NHE1 was detected via a monoclonal mouse antibody (Chemicon Int., Temecula, CA). The secondary antibody (peroxidase-conjugated anti mouse; Amersham Pharmacia Biotech Inc., Piscataway, NJ) was followed by final detection with chemiluminescence (ECL-kit, Amersham). For AB/AG competition studies, the primary antibody was preabsorbed with the peptide used for creating the antibody (Alpha Diagnostic, San Antonio, TX). Similarly, β-GlcCer’ase expression was assessed in the same samples, employing the antibody mentioned above. Equal loading per sample was controlled via individual protein content analysis and Coomassie Brilliant Blue staining of the SDS gels following transfer to PVDF membranes. Additionally, densitometry was performed on the final chemiluminescence images, using the Biorad GS-710 scanner, and Quantity One analysis software. Optical density (OD) values were first adjusted to average background density of the film, and normalization was achieved by reprobing the same PVDF membrane with an anti β-actin antibody (clone AC-74, Sigma, St. Louis, MO). Expression values were normalized within same samples, and averaged values per condition/time point compared by two-tailed t test. Finally, a percentage value for the average difference was calculated. Molecular sizes were calculated by a regression analysis based on the prestained color standards routinely used for PAGE. We first assessed the structural integrity and maturity of rat skin over the first 5 postnatal days. Light microscopy of fixed, H&E stained sagittal sections revealed a normal-appearing epidermis, although the hyperplasia in our samples was possibly less pronounced as previously reported (Hoath et al., 1993Hoath S.B. Tanaka R. Boyce S.T. Rate of stratum corneum formation in the perinatal rat.Invest Dermatol. 1993; 100: 400-406Abstract Full Text PDF PubMed Scopus (16) Google Scholar). On the first postnatal day (Fig 1, panel A), the epidermis was completely covered by a tightly apposed pcridermal layer (Fig 1, panel B). This layer began to separate into discontinuous, surface patches at day 3 (Fig 1, panel C, D), and was largely absent by day 4 (Fig 1, panel E). Electron microscopy also confirmed the presence of a continuous sheet/layer of periderm over the SC on days 1 and 2 (Fig 2, panel A; cf. Figure 1; data for day 2 not shown). By day 3, this layer became less cohesive and adherent to the underlying SC (Fig 2, panel C). Electron microscopy of ruthenium tetroxide postfixed material also revealed incompletely processed, extracellular lipids in both day 1 and day 2 postnatal SC (Fig 2, panel B; data for day 2 not shown). By day 3, however, sections revealed a normal pattern of mature, extracellular lamellar bilayers, indicative of complete lipid processing (Fig 2, panel D). Similar, mature (processed) lipid also was found in samples from postnatal days 4 and 5 (not shown). Together, these results show that neonatal SC contains barrier competent, mature structures by 3 days after birth. We next assessed changes in surface pH, using flat electrode measurements, over the first postnatal week in neonatal rats. Newborn rat SC developed an increasingly acidic pH over this period, which achieved adult levels by day 7 (Fig 3). After this date, hair growth made surface pH measurements less reliable. Traditional skin surface pH measurements, using flat electrodes, provide reliable information only about surface pH changes, without further vertical or subcellular spatial resolution; ie, specific microdomains such as the corneocytc interstices are not resolved, and the deeper SC is inaccessible without resorting to inherently disruptive stripping methods (van der Molen et al., 1997van der Molen R.G. van Spies F, ’t Noordcndc J.M. Boclsma E. Mommaas A.M. Koerten H.K. Tape stripping of human stratum corneum yields cell layers that originate from various depths because of furrows in the skin.Arch Dermatol Res. 1997; 289: 514-518Crossref PubMed Scopus (122) Google Scholar). Therefore, while a decrease in surface pH occurs during the neonatal period, more precise localization of pH/acidification in epidermal/SC microdomains that would allow elucidation of mechanistic issues is lacking. Previous studies comparing FLIM with flat electrode measurements showed that FLIM is far more sensitive than flat electrodes, and provides further information about the localized pH microenvironment of adult murine SC (Behne et al., 2002Behne M.J. Meyer J.W. Hanson K.M. et al.NHE1 regulates the stratum corneum permeability barrier homeostasis. Microenvironmcnt acidification assessed with fluorescence lifetime imaging.J Biol Chem. 2002; 277: 47399-47406Crossref PubMed Scopus (176) Google Scholar; Hanson et al., 2002Hanson K.M. Behne M.J. Barry N.P. Mauro T.M. Gratton E. Clegg R.M. Two-photon fluorescence lifetime imaging of the skin stratum corneum pH gradient.BiophysJ. 2002; 83: 1682-1690Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar). Therefore, we next assessed changes in pH distribution by FLIM in SC of newborn rats from birth through the fifth postnatal day. During the first postnatal day, only neutral pH values (>pH 6.5) were present throughout the SC, but acidity was detectable in the periderm layer at the skin surface, overlying the SC. This localized apical acidity is best seen in the pH map as the green-dotted pattern of acidic values, colocalizcd to the rounded peridermal structures (Fig 4, panel A, red arrows). The pH histograms derived from these sections demonstrate neutral values throughout the SC, notably at the SC/SG interface (Fig 4, panel B), except for localized acidity in the periderm, located above the surface of the SC (Fig 4, panel A). This pattern did not substantially change during the second postnatal day, indicating the continued presence of a neutral pH throughout the SC (data not shown). By day 3, acidic microdomains were largely, though still incompletely developed at the SC/SG interface (Fig 4, panel D), best demonstrated in the histograms, which displayed both an acidic (∼pH 6) and a neutral (∼pH 7) peak both at the surface (Fig 4, panel C and the SC/SG interface (Fig 4, panel D). By day 4, the periderm was largely absent, surface sections displayed normal SC structure, and extracellular acidity was present at all levels of the SC (Fig 4, panel E and F, blue arrows), reflecting the pattern of acidity seen in normal adult mice (Behne et al., 2002Behne M.J. Meyer J.W. Hanson K.M. et al.NHE1 regulates the stratum corneum permeability barrier homeostasis. Microenvironmcnt acidification assessed with fluorescence lifetime imaging.J Biol Chem. 2002; 277: 47399-47406Crossref PubMed Scopus (176) Google Scholar; Hanson et al., 2002Hanson K.M. Behne M.J. Barry N.P. Mauro T.M. Gratton E. Clegg R.M. Two-photon fluorescence lifetime imaging of the skin stratum corneum pH gradient.BiophysJ. 2002; 83: 1682-1690Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar). Moreover, the histograms derived from pH maps, first at day 3 and thereafter display a distribution of acidic and neutral pH spikes, which was qualitatively identical to adult murine SC, where a clear colocalization of extracellular domains with acidic pH values is apparent (Behne et al., 2002Behne M.J. Meyer J.W. Hanson K.M. et al.NHE1 regulates the stratum corneum permeability barrier homeostasis. Microenvironmcnt acidification assessed with fluorescence lifetime imaging.J Biol Chem. 2002; 277: 47399-47406Crossref PubMed Scopus (176) Google Scholar). We did not assess pH distribution in adult rats, because the epidermis becomes very thin and abundant hair follicles make assessment of SC layers by FLIM unreliable. Nevertheless, previous pH electrode measurements on adult rats revealed a pH in the acidic range (Draize, 1942Draize J.H. The determination of the pH of the skin of man and common laboratory animals.J Invest Dermatol. 1942; 5: 77-85Abstract Full Text PDF Google Scholar), although somewhat closer to neutral if measured on unshaved skin (Meyer and Neurand, 1991Meyer W. Neurand K. Comparison of skin pH in domesticated and laboratory mammals.Arch Dermatol Res. 1991; 283: 16-18Crossref PubMed Scopus (46) Google Scholar). To more precisely localize the origin and development of SC acidity, two-dimensional diagrams of pH distribution were constructed. Figure 5 displays diagrams combining a full scries of histograms from the skin surface to the SG, per postnatal day. The diagrams for days 1–3 showed acidity increasing initially in the periderm (day 1 and 3; Fig 5, panel A and B, asterisks; day 2 not shown), with values that peaked in this location at day 3. More importantly, a separate increase in acidity became distinguishable at the SC/SG interface on day 3 (Fig 5, panel B). On the 4th day, the periderm was no longer evident, and a continuously spreading, acidic pH domain that mirrored the adult-pattern “acid mantle” was present (Fig 5, panel C, with little change thereafter (day 5, Fig 5, panel D). An adult pattern of SC acidity, consisting of both an acidic (∼pH 6) and a neutral (∼pH 7) peak in the histograms of surface and SC/SG interface, is first evident in rat SC at day 3, and extends uniformly from the SC/SG interface throughout the SC by day 4. Day 5 displays the same pattern as day 4, with a slightly accentuated predominance of the inside-out generation of acidity (Fig 5, panel D). Together, these results show that acidity develops in distinct, separate membrane microdomain compartments within the SC. Initially, acidity is limited to within the periderm, and beginning on the third postnatal day, develops inside-out from the SC/SG interface, extending through the entire SC thereafter. These results also show that up to and including day 3, there is a spatial discontinuity between the acidity that develops at the SC/ SG interface and the acidity that is present at the surface, within the periderm. This discontinuity suggests that acidity at the SC/SG interface versus acidity in the periderm stem from separate processes. In our previous work, we demonstrated the importance of the sodium/hydrogen antiportcr NHE1 for SC acidification, and that this antiporter primarily acidifies the SC/SG interface (Behne et al., 2002Behne M.J. Meyer J.W. Hanson K.M. et al.NHE1 regulates the stratum corneum permeability barrier homeostasis. Microenvironmcnt acidification assessed with fluorescence lifetime imaging.J Biol Chem. 2002; 277: 47399-47406Crossref PubMed Scopus (176) Google Scholar). Since the FLIM data show that acidification begins at the SC/SG interface, and then radiates outward, we next assessed whether delayed postnatal acidification reflects a parallel delay in the expression of this proton transporter. Because it is not possible to measure NHE1 activity directly in vivo, we examined changes in antiporter expression and localization in late fetal and neonatal rat epidermis by Immunohistochemistry and Western irnrnunoblotting. Whereas NHE1 protein was only minimally evident in suprabasal layers at fetal day 17, its amount steadily increased, reaching a maximum expression in all suprabasal layers on fetal day 21, just before birth (term=day 22). Following birth, NHE1 expression continued in the SG localizing to the apical plasma membrane, where it is optimally positioned to extrude protons into t" @default.
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• W2009667054 date "2003-06-01" @default.
• W2009667054 modified "2023-10-15" @default.
• W2009667054 title "Neonatal Development of the Stratum Corneum pH Gradient: Localization and Mechanisms Leading to Emergence of Optimal Barrier Function" @default.
• W2009667054 cites W1522005841 @default.
• W2009667054 cites W1532765673 @default.
• W2009667054 cites W1554578780 @default.
• W2009667054 cites W1570503970 @default.
• W2009667054 cites W1573122791 @default.
• W2009667054 cites W1605354968 @default.
• W2009667054 cites W1897076938 @default.
• W2009667054 cites W1964904400 @default.
• W2009667054 cites W1968008704 @default.
• W2009667054 cites W1971216151 @default.
• W2009667054 cites W1973998988 @default.
• W2009667054 cites W1978141359 @default.
• W2009667054 cites W1981675297 @default.
• W2009667054 cites W1990084557 @default.
• W2009667054 cites W1990324172 @default.
• W2009667054 cites W1992987223 @default.
• W2009667054 cites W1993379676 @default.
• W2009667054 cites W1996940153 @default.
• W2009667054 cites W1997673339 @default.
• W2009667054 cites W2012647985 @default.
• W2009667054 cites W2018673693 @default.
• W2009667054 cites W2025083169 @default.
• W2009667054 cites W2027386197 @default.
• W2009667054 cites W2029936361 @default.
• W2009667054 cites W2031629302 @default.
• W2009667054 cites W2040459675 @default.
• W2009667054 cites W2043082205 @default.
• W2009667054 cites W2044364035 @default.
• W2009667054 cites W2045098982 @default.
• W2009667054 cites W2049593244 @default.
• W2009667054 cites W2052773588 @default.
• W2009667054 cites W2055206016 @default.
• W2009667054 cites W2061712385 @default.
• W2009667054 cites W2064146585 @default.
• W2009667054 cites W2070935457 @default.
• W2009667054 cites W2072503318 @default.
• W2009667054 cites W2072756220 @default.
• W2009667054 cites W2073074765 @default.
• W2009667054 cites W2076474107 @default.
• W2009667054 cites W2077672204 @default.
• W2009667054 cites W2088798928 @default.
• W2009667054 cites W2090400502 @default.
• W2009667054 cites W2098534191 @default.
• W2009667054 cites W2100837269 @default.
• W2009667054 cites W2102841893 @default.
• W2009667054 cites W2144471230 @default.
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