Letter: Zinc in acrodermatis enteropathica

Effects of non-toxic zinc exposure on human epidermal keratinocytes

Zinc is an essential microelement; its importance to the skin is highlighted by the severe skin symptoms in hereditary or acquired zinc deficiency, by the improvement of several skin conditions using systemic or topical zinc preparations and by the induced intracellular zinc release upon UVB exposure, which is the main harmful environmental factor to the skin. Understanding the molecular background of the role of zinc in skin may help gain insight into the pathology of skin disorders and provide evidence for the therapeutic usefulness of zinc supplementation. Herein, we studied the effects of zinc chloride (ZnCl2) exposure on the function of HaCaT keratinocytes, and the results showed that a non-toxic elevation in the concentration of extracellular zinc (100 μM) facilitated cell proliferation and induced significant alterations in the mRNA expression of NOTCH1, IL8, and cyclooxygenase-2. In addition, increased heme oxygenase-1 (HMOX1) expression and non-toxic generation of superoxide were detected in the first 4 h. Regarding the effects on the UVB-induced toxicity, although the level of cyclobutane pyrimidine dimers in the keratinocytes pre-treated with zinc for 24 h was reduced 3 h after UVB irradiation, significantly enhanced superoxide generation was observed 10 h after UVB exposure in the zinc pre-exposed cells. The overall survival was unaffected; however, there was a decrease in the percentage of early apoptotic cells and an increase in the percentage of late apoptotic plus necrotic cells. These results suggest that the exposure of human keratinocytes to non-toxic concentrations of ZnCl2 impacts gene expression, cell proliferation and the responses to environmental stress in the skin. It would be important to further examine the role of zinc in skin and further clarify whether this issue can affect our thinking regarding the pathogenesis of skin diseases.

The role of zinc in Candida dimorphism

By analyzing the effects of zinc on growth and dimorphism, it has become clear that there exists at least two modes, or "pathways," of mycelium formation in C. albicans (7). Paradoxically, even though the characteristics for the two modes appear to be opposite in nature, the mycelium that form appear to be superficially similar. Unfortunately, it may be difficult to compare the two modes unambiguously at the molecular level for two reasons. First, the physiology of cells resuming growth after release from stationary phase will undoubtedly differ drastically from the physiology of cells exiting from the growth cycle, regardless of phenotype. Therefore, most molecular or physiologic differences probably will represent differences in growth rate or position in the cell cycle, rather than alternate molecular mechanisms that are basic to the alternate modes of mycelium formation. Second, it has been observed that during release from stationary phase, a prescribed program of gene expression accompanies commitment to the mycelial and budding forms (11). This program was demonstrable because of the excellent synchrony and homogeneity of released cultures (60), which is a characteristic lacking in cultures entering stationary phase in the M10 mode. Even so, a comparison at the molecular level between the two modes of mycelium formation should be undertaken with the above reservations in mind. Perhaps the most attractive aspect of alternate modes of mycelium formation in Candida is at the genetic level of analysis. The hypothesis of homozygosis in the expression of the M10 phenotype is testable, as is the possible role of the M10 phenotype in tissue penetration. If the hypothesis is true and if the M10 phenotype predominates in infected tissue, it would represent a new mechanism of opportunism in infectious fungi that may be used by other systems as well as Candida. If it is not true, a detailed analysis of the differences between the two modes of mycelium formation will still be valuable in our understanding of both the mechanisms regulating phenotypic transitions in Candida and the more general question of cell divergence in developing systems.

Lymphocyte and granulocyte function in zinc-treated and zinc-deficient hemodialysis patients

Lymphocyte blast transformation and granulocyte motility were studied in 20 clinically stable hemodialysis patients, 10 of whom were receiving 50 mg of zinc (as zinc acetate) per day and 10 of whom were not. Plasma zinc concentration was significantly higher in zinc-treated than in untreated patients (108 +/- 5 vs. 82 +/- 2 micrograms/dl). Mononuclear cell subpopulation analysis showed equivalent proportions of T lymphocytes and monocytes in both groups, but B lymphocytes were reduced in untreated patients (10 +/- 0.7 vs 14 +/- 0.5%). Lymphocyte blast transformations in response to nonspecific mitogens, soluble antigen and mixed lymphocyte culture were not significantly different in the two groups, nor was lymphocyte zinc concentration. Zinc-treated patients showed significantly greater granulocyte responsiveness to zymosan-activated serum (21 +/- 1 vs. 14 +/- 2 mean), greater chemokinetic activity (50 +/- 4 vs. 27 +/- 3 mean) and higher granulocyte zinc concentration (114 +/- 6 vs. 47 +/- 2 micrograms/10(6) cells) than untreated patients. Granulocyte zinc correlated significantly with plasma zinc (r = 0.81, P less than 0.001) and with granulocyte motility (r = 0.63, P = 0.001). Moderate zinc deficiency in hemodialysis patients does not result in abnormal lymphocyte blast transformation in vitro, but it does result in granulocyte zinc depletion and impaired granulocyte motility.

Acrodermatitis enteropathica

Acrodermatisis enteropathical has had a remarkable hist orical course beginning only 35 years ago, first passing through a period of empiric management with the 8-hydroxyquinoline drugs and culminating with the discovery of a biochemical effect in zinc absorption. This accomplishment has not only resulted in the cure of a serious and often fatal disease, but has opened the way to an understanding of the vital role played by the trace element zinc in many previously unrecognized areas of human physiology.

Acrodermatitis enteropathica: recent findings concerning clinical features, pathogenesis, diagnosis and therapy

Acrodermatitis enteropathica (AE) was diagnosed in 2 siblings, boy and girl, at the age of 10 and 6 weeks. The family history is unremarkable except for consanguinity 5 generations previously. The clinical symptoms of the 2 patients conformed to the known features of AE, the gastrointestinal involvement loosing its significance with increasing age. In one patient in a stage of exacerbation the serum level of oleic acid (18:1) was lowered and of linoleic (18:2) acid slightly increased while that of arachidonic acid was decreased (Fig. 4). In both patients the serum zinc levels were significantly lowered. Under substitution with ZnSO4 the clinical condition improved and the serum zinc levels returned to normal. Histologically the small bowel mucosa was practically normal. Ultrastructural examination of jejunal biopsies revealed rather unspecific changes in the enterocytes in the form of numerous multivesicular bodies. The Paneth cells sometimes contained irregularly formed inhomogeneous structures within their cytoplasm. In addition the secretory granules varied in size and displayed a granular heteromorphic matrix. Frequently they were confluent and formed giant granules.

Treatment of acrodermatitis enteropathica with zinc sulphate

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