Effect of allergens and irritants on levels of natural moisturizing factor and corneocyte morphology

Abstract

SummaryBackgroundThe irritant sodium lauryl sulfate (SLS) is known to cause a decrease in the stratum corneum level of natural moisturizing factor (NMF), which in itself is associated with changes in corneocyte surface topography.ObjectiveTo explore this phenomenon in allergic contact dermatitis.MethodsPatch testing was performed on patients with previously positive patch test reactions to potassium dichromate (Cr), nickel sulfate (Ni), methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), or p‐phenylenediamine. Moreover, a control (pet.) patch and an irritant (SLS) patch were applied. After 3 days, the stratum corneum from tested sites was collected, and NMF levels and corneocyte morphology, expressed as the amount of circular nanosize objects, quantified according to the Dermal Texture Index (DTI), were determined.ResultsAmong allergens, only MCI/MI reduced NMF levels significantly, as did SLS. Furthermore, only MCI/MI caused remarkable changes at the microscopic level; the corneocytes were hexagonal‐shaped with pronounced cell borders and a smoother surface. The DTI was increased after SLS exposure but not after allergen exposure.Conclusions MCI/MI significantly decreased NMF levels, similarly to SLS. The altered corneocyte morphology suggests that skin barrier damage plays a role in the pathogenesis of MCI/MI contact allergy. The DTI seems to differentiate reactions to SLS from those to the allergens tested, as SLS was the only agent that caused a DTI increase.

The role of skin barrier in occupational contact dermatitis

“…Interestingly, Kohli and Nedorost found that AD predisposes to sensitization only to less potent allergens arguing that potent sensitizers are often strong irritants that damage the skin barrier and trigger innate immune response needed for the induction of allergic response. Consistently, Koppes et al reported that a strong contact allergen methyl⁄chloromethylisothiazolinone known for its corrosive and irritant properties causes remarkable alterations of the corneocyte surface topography and reduction in NMF, similarly to SLS. This effect was, however, not seen for nickel, a less irritant contact allergen.…”

“…As an alkaline detergent, SLS increases the pH of the SC affecting the activity of serine proteases (especially KLK5 and KLK7), which are known effectors of desquamation and lipid synthesis . Next, SLS dramatically decreased NMF, and this decrease was correlated with a decrease in SC hydration and changes in corneocyte surface topography . Of note, NMF is not only important for skin hydration, but also for the conformation of the keratin fibres within the corneocytes, pH of the SC and the SC levels of IL‐1 cytokines .…”

Specific barrier response profiles after experimentally induced skin irritation in vivo

“…The pathomechanism of ICD remains incompletely understood; however, impairment of the skin barrier function plays a central role, triggering homeostatic and innate immune responses . Recently, Koppes et al reported 2 novel biomarkers of irritant skin reactions to sodium lauryl sulfate (SLS): the dermal texture index (DTI) as a measure of the corneocyte topography, and the levels of natural moisturizing factors (NMFs). As shown by the use of atomic force microscopy (AFM), SLS dramatically increased the number of circular nano‐objects protruding above the corneocyte surface, as shown by the DTI, and decreased NMF levels at the same time.…”

“…Recently, Koppes et al reported 2 novel biomarkers of irritant skin reactions to sodium lauryl sulfate (SLS): the dermal texture index (DTI) as a measure of the corneocyte topography, and the levels of natural moisturizing factors (NMFs). As shown by the use of atomic force microscopy (AFM), SLS dramatically increased the number of circular nano‐objects protruding above the corneocyte surface, as shown by the DTI, and decreased NMF levels at the same time. In contrast to the SLS‐induced increase in the DTI, no changes in the DTI were observed in skin affected by allergic contact dermatitis .…”

“…As shown by the use of atomic force microscopy (AFM), SLS dramatically increased the number of circular nano‐objects protruding above the corneocyte surface, as shown by the DTI, and decreased NMF levels at the same time. In contrast to the SLS‐induced increase in the DTI, no changes in the DTI were observed in skin affected by allergic contact dermatitis . These observations suggest that the alterations in the corneocyte surface topography might be attributed to the skin barrier damage caused by the irritant, rather than to inflammation itself .…”