Relationship of adhesion molecules expression with epithelial differentiation markers during fetal skin development

Immunoexpression of adhesion molecules during human fetal hair development

INTRODUCTION

Hair follicles are produced in a cyclical manner and the machinery involved in the reproduction of these follicles is present since the fetal stage. Although extensive research has been done on the human hair follicle, very little is known about the importance of adhesion molecules in its development.

MATERIAL AND METHODS

We analyzed here, the immunoexpression of beta-1 integrin, p-cadherin, e-cadherin, and beta-catenin in hair follicles from 26 formalin-fixed and paraffin-embedded skin samples from human embryos and fetus between 12-23 weeks of gestational age.

RESULTS

The adhesion molecules beta-1 integrin and e-cadherin/p-cadherin were expressed from 12 weeks and seemed to play a role in regulating epidermis invagination. Beta-catenin immunostaining was negative in all cases; down regulation of this protein may be necessary for fetal hair development and thus facilitating hair follicle down growth.

DISCUSSION/CONCLUSION

Adhesion molecules are essential for hair follicle down growth and proliferation; integrins and cadherins play a major role in this process. More studies are needed to describe hair follicle development.

Immunostaining study of cytokeratins in human hair follicle development

Background

The hair follicle is a unique structure, one of the most dynamic structures in mammalians, which can reproduce in every new cycle all the mechanism involved in its fetal development. Although a lot of research has been made about the human hair follicle much less has been discovered about the importance of the cytokeratins (CKs) in its development.

Objective

Study the immunohistochemical pattern of epithelial CKs during human hair follicle development.

Methods

We performed an immunohistochemical study using fresh post-mortem skin biopsies of human fetuses between 4 and 25 weeks of gestational age to study the expression of cytokeratins (CKs): CK1, CK10, CK13, CK14, CK16 and CK20 during human hair follicle fetal development.

Study limitations

Restrospective study with a good number of makers but with a small population.

Results/conclusion

We found that, the CKs were expressed in an intermediate time during follicular development. The epithelial CKs (CK1, CK14, CK10, CK13) and the epithelial CKs with a proliferative character such as CK16 were expressed first, as markers of cellular maturation and follicular keratinization. At a later phase, CK20 was expressed in more developed primitive hair follicles as previously discussed in literature.

Connecting cyto-nano-architectural attributes and epithelial molecular expression in oral submucous fibrosis progression to cancer

OBJECTIVE

Problems in pre-cancer diagnosis complicate cancer theragnosis as well as life expectancy. There is uncertainty regarding malignant transformation of oral submucous fibrosis (OSF), an oral pre-cancer with dysplastic (OSFWD) and non-dysplastic (OSFWT) subtypes. Understanding the structural, molecular and physical aspects of epithelial homeostasis may be useful.

MATERIALS AND METHODS

Histopathological grading of biopsy sections was performed using H&E staining. Alterations in epithelial surface architecture in different groups was evaluated using scanning electron microscopy (SEM). The expression of crucial epithelial genes (p63, CK-5/6, CK-10, E-cadherin and β-catenin) was studied by immunohistochemistry, Western blot and RT-PCR analysis.

RESULTS

SEM observations revealed that the surface epithelial ridge pattern became thick and dense, and pit pattern gradually decreased in OSFWD and oral squamous cell carcinoma (OSCC). p63, ΔNp63 and CK-5/6 were up-regulated in OSFWD and OSCC but down-regulated in OSFWT. CK-10 was down-regulated in OSFWD compared to OSFWT. Cytoplasmic expression of E-cadherin and β-catenin was elevated in dysplastic and cancerous conditions. Moreover, statistical correlation between SEM features (ridges and pits) and molecular attributes demonstrated a significant positive relationship between the ridge-to-pit ratio and p63 population density (r=0.85) and the ridge-to-pit ratio and CK-5/6 intensity (r=0.63).

CONCLUSIONS

Molecular changes related to epithelial progressive maturation and cellular proliferation are correlated with concomitant alteration of epithelial surface architecture which helps to predict the malignant potentiality of OSF.

Desmosomes in developing human epidermis

Desmosomes play important roles in the cell differentiation and morphogenesis of tissues. Studies on animal models have greatly increased our knowledge on epidermal development while reports on human developing skin are rare due to the difficult accessibility to the samples. Although the morphology of periderm cells and the process how the epidermis develops very much resemble each other, the timetable and the final outcome of a mature human epidermis markedly differ from those of murine skin. Even the genetic basis of the junctional components may have profound differences between the species, which might affect the implementation of the data from animal models in human studies. The aim of this review is to focus on the development of human skin with special emphasis on desmosomes. Desmosomal development is mirrored in perspective with other simultaneous events, such as maturation of adherens, tight and gap junctions, and the basement membrane zone.

Comparison between human fetal and adult skin

Healing of early-gestation fetal wounds results in scarless healing. Since the capacity for regeneration is probably inherent to the fetal skin itself, knowledge of the fetal skin composition may contribute to the understanding of fetal wound healing. The aim of this study was to analyze the expression profiles of different epidermal and dermal components in the human fetal and adult skin. In the human fetal skin (ranging from 13 to 22 weeks' gestation) and adult skin biopsies, the expression patterns of several epidermal proteins (K10, K14, K16, K17, SKALP, involucrin), basement membrane proteins, Ki-67, blood vessels and extracellular matrix proteins (fibronectin, chondroitin sulfate, elastin) were determined using immunohistochemistry. The expression profiles of K17, involucrin, dermal Ki-67, fibronectin and chondroitin sulfate were higher in the fetal skin than in adult skin. In the fetal skin, elastin was not present in the dermis, but it was found in the adult skin. The expression patterns of basement membrane proteins, blood vessels, K10, K14, K16 and epidermal Ki-67 were similar in human fetal skin and adult skin. In this systematic overview, most of the differences between fetal and adult skin were found at the level of dermal extracellular matrix molecules expression. This study suggests that, especially, dermal components are important in fetal scarless healing.