Disclosure of ultraviolet (UV) radiation is the key feature from environment to cause redness of the skin, inflammation, photoaging and skin cancer. 6-Shogaol, a spicy compound secluded from ginger, ...which shows anti-inflammatory effects. Present study was demonstrated the role of 6-Shogaol on UVB induced oxidative stress and photoaging signaling in human epidermal keratinocytes (HaCaT cells). In this study, UVB-irratiation (180 mJ/cm2) significantly elevated the intracellular ROS levels, depletion of antioxidants resulted in apoptotic HaCaT cells. MAPKs signaling are concerned in oxidative stress; these signaling events are measured as differentiation. We found that 6-shogaol prevents over expression of MAPKs (ERK1, JNK1 & p38), in disclosure of UVB in HaCaT cells. Moreover, 6-shogaol infringed Bax and Bcl-2 in which 20 μg 6-shogaol influenced apoptosis in HaCaT cells by investigating augmented appearance of Bax and condensed appearance of Bcl-2 in contrast to control HaCaT cells. These results suggest that 6-shogaol could be a successful healing agent provides fortification against UVB-induced provocative and oxidative skin reimbursement.
•Disclosure of ultraviolet radiation is the key feature from environment to cause inflammation and photoaging.•6-shogaol repressed the UVB induced inflammation retortion which includes the improved appearance of iNOS, COX-2, and TNF-α.•6-shogaol might be an effectual defensive and healing agent shielding against UVB induced skin reimbursement.
Keratinocyte differentiation program leading to an organized epidermis plays a key role in maintaining the first line of defense of the skin. Epidermal integrity is regulated by a tight communication ...between keratinocytes and leucocytes, particularly under cytokine control. Imbalance of the cytokine network leads to inflammatory diseases such as psoriasis. Our attempt to model skin inflammation showed that the combination of IL-17A, IL-22, IL-1α, OSM and TNFα (Mix M5) synergistically increases chemokine and antimicrobial-peptide expression, recapitulating some features of psoriasis. Other characteristics of psoriasis are acanthosis and down-regulation of keratinocyte differentiation markers. Our aim was to characterize the specific roles of these cytokines on keratinocyte differentiation, and to compare with psoriatic lesion features. All cytokines decrease keratinocyte differentiation markers, but IL-22 and OSM were the most powerful, and the M5 strongly synergized the effects. In addition, IL-22 and OSM induced epidermal hyperplasia in vitro and M5 induced epidermal thickening and decreased differentiation marker expression in a mouse model, as observed in human psoriatic skin lesions. This study highlights the precise role of cytokines in the skin inflammatory response. IL-22 and OSM more specifically drive epidermal hyperplasia and differentiation loss while IL-1α, IL-17A and TNFα were more involved in the activation of innate immunity.
Junctional epidermolysis bullosa (JEB) is a severe and often lethal genetic disease caused by mutations in genes encoding the basement membrane component laminin-332. Surviving patients with JEB ...develop chronic wounds to the skin and mucosa, which impair their quality of life and lead to skin cancer. Here we show that autologous transgenic keratinocyte cultures regenerated an entire, fully functional epidermis on a seven-year-old child suffering from a devastating, life-threatening form of JEB. The proviral integration pattern was maintained in vivo and epidermal renewal did not cause any clonal selection. Clonal tracing showed that the human epidermis is sustained not by equipotent progenitors, but by a limited number of long-lived stem cells, detected as holoclones, that can extensively self-renew in vitro and in vivo and produce progenitors that replenish terminally differentiated keratinocytes. This study provides a blueprint that can be applied to other stem cell-mediated combined ex vivo cell and gene therapies.
Human NLRP1 is a sensor for double-stranded RNA Bauernfried, Stefan; Scherr, Matthias J; Pichlmair, Andreas ...
Science (American Association for the Advancement of Science),
01/2021, Volume:
371, Issue:
6528
Journal Article
Peer reviewed
Open access
Inflammasomes function as intracellular sensors of pathogen infection or cellular perturbation and thereby play a central role in numerous diseases. Given the high abundance of NLRP1 in epithelial ...barrier tissues, we screened a diverse panel of viruses for inflammasome activation in keratinocytes. We identified Semliki Forest virus (SFV), a positive-strand RNA virus, as a potent activator of human but not murine NLRP1B. SFV replication and the associated formation of double-stranded (ds) RNA was required to engage the NLRP1 inflammasome. Moreover, delivery of long dsRNA was sufficient to trigger activation. Biochemical studies revealed that NLRP1 binds dsRNA through its leucine-rich repeat domain, resulting in its NACHT domain gaining adenosine triphosphatase activity. Altogether, these results establish human NLRP1 as a direct sensor for dsRNA and thus RNA virus infection.
As the most dominant cell type in the skin, keratinocytes play critical roles in wound repair not only as structural cells but also exerting important immune functions. This review focuses on the ...communications between keratinocytes and immune cells in wound healing, which are mediated by various cytokines, chemokines, and extracellular vesicles. Keratinocytes can also directly interact with T cells via antigen presentation. Moreover, keratinocytes produce antimicrobial peptides that can directly kill the invading pathogens and contribute to wound repair in many aspects. We also reviewed the epigenetic mechanisms known to regulate keratinocyte immune functions, including histone modifications, non-protein-coding RNAs (e.g., microRNAs, and long noncoding RNAs), and chromatin dynamics. Lastly, we summarized the current evidence on the dysregulated immune functions of keratinocytes in chronic nonhealing wounds. Based on their crucial immune functions in skin wound healing, we propose that keratinocytes significantly contribute to the pathogenesis of chronic wound inflammation. We hope this review will trigger an interest in investigating the immune roles of keratinocytes in chronic wound pathology, which may open up new avenues for developing innovative wound treatments.
Integrity of human skin is endangered by exposure to UV irradiation and chemical stressors, which can provoke a toxic production of reactive oxygen species (ROS) and oxidative damage. Since oxidation ...of proteins and metabolites occurs virtually instantaneously, immediate cellular countermeasures are pivotal to mitigate the negative implications of acute oxidative stress. We investigated the short-term metabolic response in human skin fibroblasts and keratinocytes to H2O2 and UV exposure. In time-resolved metabolomics experiments, we observed that within seconds after stress induction, glucose catabolism is routed to the oxidative pentose phosphate pathway (PPP) and nucleotide synthesis independent of previously postulated blocks in glycolysis (i.e., of GAPDH or PKM2). Through ultra-short 13C labeling experiments, we provide evidence for multiple cycling of carbon backbones in the oxidative PPP, potentially maximizing NADPH reduction. The identified metabolic rerouting in oxidative and non-oxidative PPP has important physiological roles in stabilization of the redox balance and ROS clearance.
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•Oxidants induce rerouting of glucose flux into oxidative PPP within seconds•Initial rerouting is independent of GADPH or PKM2 inhibition•Multiple cycling of carbon molecules in PPP potentially amplifies NADPH production•PPP activation might be involved in resistance against ROS-based cancer therapies
The human skin is continuously exposed to oxidative stress induced by UV irradiation. Kuehne and Emmert et al. report how skin cells reroute glucose flux into the oxidative pentose phosphate pathway as a first-line defense to increase NADPH production, which is essential to prevent oxidative damage.
Staphylococcus aureus commonly colonizes the epidermis, but the mechanisms by which the host senses virulent, but not commensal, S. aureus to trigger inflammation remain unclear. Using a ...murine epicutaneous infection model, we found that S. aureus-expressed phenol-soluble modulin (PSM)α, a group of secreted virulence peptides, is required to trigger cutaneous inflammation. PSMα induces the release of keratinocyte IL-1α and IL-36α, and signaling via IL-1R and IL-36R was required for induction of the pro-inflammatory cytokine IL-17. The levels of released IL-1α and IL-36α, as well as IL-17 production by γδ T cells and ILC3 and neutrophil infiltration to the site of infection, were greatly reduced in mice with total or keratinocyte-specific deletion of the IL-1R and IL-36R signaling adaptor Myd88. Further, Il17a−/−f−/− mice showed blunted S. aureus-induced inflammation. Thus, keratinocyte Myd88 signaling in response to S. aureus PSMα drives an IL-17-mediated skin inflammatory response to epicutaneous S. aureus infection.
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•S. aureus virulence factor PSMα induces the release of keratinocyte IL-1α and IL-36α•Myd88 signaling in keratinocytes is required for IL-1α and IL-36α production•IL-1R and IL-36R signaling is critical for the induction of IL-17-producing cells•Mice deficient in IL-17A/F show blunted S. aureus-induced skin inflammation
Nakagawa et al. demonstrate that S. aureus produces PSMα, a group of virulence peptides, to induce keratinocyte damage and release of IL-1α and IL-36α. IL-1R and IL-36R signaling via the adaptor Myd88 induces IL-17-producing γδ T cells and ILC3, which critically mediate skin inflammation in response to epicutaneous S. aureus.
Solar ultraviolet radiation (UVR)-induced DNA damage has acute, and long-term adverse effects in the skin. This damage arises directly by absorption of UVR, and indirectly via photosensitization ...reactions. The aim of the present study was to assess the effects of vitamin E on UVAI-induced DNA damage in keratinocytes in vitro. Incubation with vitamin E before UVAI exposure decreased the formation of oxidized purines (with a decrease in intracellular oxidizing species), and cyclobutane pyrimidine dimers (CPD). A possible sunscreening effect was excluded when similar results were obtained following vitamin E addition after UVAI exposure. Our data showed that DNA damage by UVA-induced photosensitization reactions can be inhibited by the introduction of vitamin E either pre- or post-irradiation, for both oxidized purines and CPD (including so-called "dark" CPDs). These data validate the evidence that some CPD are induced by UVAI initially via photosensitization, and some via chemoexcitation, and support the evidence that vitamin E can intervene in this pathway to prevent CPD formation in keratinocytes. We propose the inclusion of similar agents into topical sunscreens and aftersun preparations which, for the latter in particular, represents a means to mitigate on-going DNA damage formation, even after sun exposure has ended.
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