Amniotic Fluid Activates the Nrf2/Keap1 Pathway to Repair an Epidermal Barrier Defect In Utero (original) (raw)
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Effects of amniotic fluid on human keratinocyte gene expression: Implications for wound healing
Experimental Dermatology, 2022
Cutaneous wound healing is a clinically important field of research where the translation of new treatment options is desperately needed. The healing process involves innate and adaptive immunity. Blood factors and all the cells and compartments of the integumentary system compromise a complex structure that presents many potential targets for intervention. Inflammatory cascades and the re-establishment of epithelial integrity marks the early phase of cutaneous wound healing whilst tissue remodelling and the return of further skin functions occur at later stages of the healing process. 1 The realisation that early fetal wounds heal with tissue regeneration instead of scarring suggests an instructive role of the embryonic environment in regulating the response to wounding. 2 The
Nrf2 links epidermal barrier function with antioxidant defense
EMBO Molecular Medicine, 2012
The skin provides an efficient permeability barrier and protects from microbial invasion and oxidative stress. Here, we show that these essential functions are linked through the Nrf2 transcription factor. To test the hypothesis that activation of Nrf2 provides skin protection under stress conditions, we determined the consequences of pharmacological or genetic activation of Nrf2 in keratinocytes. Surprisingly, mice with enhanced Nrf2 activity in keratinocytes developed epidermal thickening, hyperkeratosis and inflammation resembling lamellar ichthyosis. This resulted from upregulation of the cornified envelope proteins small proline-rich proteins (Sprr) 2d and 2h and of secretory leukocyte peptidase inhibitor (Slpi), which we identified as novel Nrf2 targets in keratinocytes. Since Sprrs are potent scavengers of reactive oxygen species and since Slpi has antimicrobial activities, their upregulation contributes to Nrf2's protective function. However, it also caused corneocyte fragility and impaired desquamation, followed by alterations in the epidermal lipid barrier, inflammation and overexpression of mitogens that induced keratinocyte hyperproliferation. These results identify an unexpected role of Nrf2 in epidermal barrier function, which needs to be considered for pharmacological use of Nrf2 activators.
Amniotic membrane stimulates cell migration by modulating Transforming Growth Factor-β signaling
Journal of tissue engineering and regenerative medicine, 2017
Keratinocyte migration is a mandatory aspect of wound-healing. We have previously shown that Amniotic Membrane (AM) applied to chronic wounds assists healing through a process resulting in overexpression of c-Jun at the wound's leading edge. Also, we have demonstrated that amniotic membrane modifies the genetic program induced by TGF-ß in chronic wounds. In this paper, we used a scratch assay of Mv1Lu and HaCaT cells to examine the influence of AM application on the underlying signaling during scratch closure. AM-application induced c-Jun phosphorylation at the leading-edge of scratch wounds in a process dependent on MAPK and JNK signaling. Strikingly, when the TGF-ß-dependent Smad-activation inhibitor SB431542 was used together with AM, migration improvement was partially restrained, while addition of TGF-ß had a synergistic effect on the AM induced cell migration. Moreover, antagonizing TGF-ß with specific antibodies in both cell lines or knocking out TGF-ß receptors in Mv1Lu ...
Epidermal Immunity and Function: Origin in Neonatal Skin
Frontiers in Molecular Biosciences, 2022
The fascinating story of epidermal immunity begins in utero where the epidermal barrier derives from the ectoderm and evolves through carefully orchestrated biological processes, including periderm formation, keratinocyte differentiation, proliferation, cornification, and maturation, to generate a functional epidermis. Vernix caseosa derives from epidermal cells that mix with sebaceous lipids and coat the fetus during late gestation, likely to provide conditions for cornification. At birth, infants dramatically transition from aqueous conditions to a dry gaseous environment. The epidermal barrier begins to change within hours, exhibiting decreased hydration and low stratum corneum (SC) cohesion. The SC varied by gestational age (GA), transformed over the next 2–3 months, and differed considerably versus stable adult skin, as indicated by analysis of specific protein biomarkers. Regardless of gestational age, the increased infant SC proteins at 2–3 months after birth were involved in...
Cells, 2021
Amniotic epithelial stem cells (AESCs) are considered as potential alternatives to keratinocytes (KCs) in tissue-engineered skin substitutes used for treating skin damage. However, their clinical application is limited since similarities and distinctions between AESCs and KCs remain unclear. Herein, a transcriptomics analysis and functional evaluation were used to understand the commonalities and differences between AESCs and KCs. RNA-sequencing revealed that AESCs are involved in multiple epidermis-associated biological processes shared by KCs and show more similarity to early stage immature KCs than to adult KCs. However, AESCs were observed to be heterogeneous, and some possessed hybrid mesenchymal and epithelial features distinct from KCs. A functional evaluation revealed that AESCs can phagocytose melanosomes transported by melanocytes in both 2D and 3D co-culture systems similar to KCs, which may help reconstitute pigmented skin. The overexpression of TP63 and activation of NO...
Frontiers in Bioengineering and Biotechnology, 2021
The application of amniotic membrane (AM) on chronic wounds has proven very effective at resetting wound healing, particularly in re-epithelialization. Historically, several aspects of AM effect on wound healing have been evaluated using cell models. In keratinocytes, the presence of AM induces the activation of mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK) pathways, together with the high expression of c-Jun, an important transcription factor for the progression of the re-epithelialization tongue. In general, the levels of transforming growth factor (TGF)-β present in a wound are critical for the process of wound healing; they are elevated during the inflammation phase and remain high in some chronic wounds. Interestingly, the presence of AM, through epidermal growth factor (EGF) signaling, produces a fine-tuning of the TGF-β signaling pathway that re-conducts the stalled process of wound healing. However, the complete suppression of TGF-β signaling has p...
Keratin 8 protection of placental barrier function
The Journal of Cell Biology, 2003
he intermediate filament protein keratin 8 (K8) is critical for the development of most mouse embryos beyond midgestation. We find that 68% of K8 Ϫ / Ϫ embryos, in a sensitive genetic background, are rescued from placental bleeding and subsequent death by cellular complementation with wild-type tetraploid extraembryonic cells. This indicates that the primary defect responsible for K8 Ϫ / Ϫ lethality is trophoblast giant cell layer failure. Furthermore, the genetic absence of maternal but not paternal TNF doubles the number of viable K8 Ϫ / Ϫ embryos. Finally, we show that K8 Ϫ / Ϫ concepti are more sensitive to a TNF-dependent epithelial T apoptosis induced by the administration of concanavalin A (ConA) to pregnant mothers. The ConA-induced failure of the trophoblast giant cell barrier results in hematoma formation between the trophoblast giant cell layer and the embryonic yolk sac in a phenocopy of dying K8-deficient concepti in a sensitive genetic background. We conclude the lethality of K8 Ϫ / Ϫ embryos is due to a TNF-sensitive failure of trophoblast giant cell barrier function. The keratindependent protection of trophoblast giant cells from a maternal TNF-dependent apoptotic challenge may be a key function of simple epithelial keratins.
Wound Repair and Regeneration Official Publication of the Wound Healing Society and the European Tissue Repair Society, 2010
Fetuses and adults follow different repair strategies for the healing of skin wounds. Experimental evidence indicates that this most probably reflects the intrinsic characteristics of fetal tissue, although environmental factors may also contribute to this phenomenon. Accordingly, the aim of the present study was to investigate the effect of the in utero environment, i.e., amniotic fluid, on one of the major parameters of wound healing, namely cell proliferation, and especially its effect on cultures of both human fetal and adult skin fibroblasts. We found that second trimester human amniotic fluid is a potent stimulant of DNA synthesis and proliferation of cells from both developmental stages. This effect is due to the presence of growth factors, especially basic fibroblast growth factor and platelet-derived growth factor, because inhibitors of their respective receptor kinases and specific neutralizing antibodies can significantly inhibit cell proliferation. Furthermore, we found that this mitogenic effect is mediated through the activation of the MEK/ERK and the PI3K/Akt signaling pathways. Interestingly, we have not observed any significant differences between fetal and adult fibroblasts in their response to amniotic fluid, indicating that cells from both developmental stages respond equally to this complex mixture of regulatory molecules.
International Journal of Molecular Sciences
Unsuccessful wound closure in chronic wounds can be linked to altered keratinocyte activation and their inability to re-epithelize. Suggested mechanisms driving this impairment involve unbalanced cytokine signaling. However, the molecular events leading to these aberrant responses are poorly understood. Among cytokines affecting keratinocyte responses, Transforming Growth Factor-β (TFG-β) is thought to have a great impact. In this study, we have used a previously characterized skin epidermal in vitro model, HaCaT cells continuously exposed to TGF-β1, to study the wound recovery capabilities of chronified/senescent keratinocytes. In this setting, chronified keratinocytes show decreased migration and reduced activation in response to injury. Amniotic membrane (AM) has been used successfully to manage unresponsive complicated wounds. In our in vitro setting, AM treatment of chronified keratinocytes re-enabled migration in the early stages of wound healing, also promoting proliferation ...