Maintenance of skin physical and immune barrier synergy via CLASP2 and JAK-STAT pathway interaction
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Presented by: Yicheng Xu
Introduction: In recent years, climate change has become a growing concern, affecting every aspect of our lives. As the outermost layer of the body to the external environment, the integrity of the skin barrier is particularly important. The skin barrier is mainly composed of the epidermis-based physical barrier and the immune barrier formed by various immune response networks. CLASP2 is involved in cell-cell adhesion preservation in epidermal stem cells and prevents keratinocyte differentiation disorders, which are important for epidermal architecture maintenance. The JAK-STAT (Janus kinase/signal transducer and activator of transcription) pathway is one of the major mechanisms that regulates the production of cytokines, which play a main role in the innate immune response. But the interaction between CLASP2 and JAK-STAT pathway in skin cells remains unclear. The purpose of this study was to understand the possibility of maintaining the synergy of two skin barrier systems through CLASP2 and JAK-STAT pathway interaction.
Methods: We first investigated the epidermal barrier function. Human primary keratinocytes (NHEKs) were obtained from a mature female donor. Cells were pre-incubated during 24 hours. At the end of the pre-incubation period, CLASP2 protein was quantified in cell lysates. Epidermal stem cells were obtained following the method described by Goodell et al. and were irradiated by UVB (30mJ/cm2). Cell viability has been measured using Alamar blue. C. Acnes lysate at a final concentration of 2.108 UFC was used as lipopolysaccharide (LPS). Cells were then incubated with LPS for 24 hours. At the end of the incubation period, p-STAT3, NLRP3 and IL-1 beta protein levels were measured in cell lysates. In order to evaluate the wound healing effect, a scratch of around 1mm of width has been performed in the NHEKs monolayer culture. The area of the injury at Day 0 and the non-recolonized area at Day 3 were measured by image analysis using the Image J software.
Results: In NHEKs, the CLASP2 synthesis was significantly increased by a Mushroom-Based Skin Protectant (MBSP). The latter significantly protected epidermal stem cells from UVB stress, which coincided with the trend towards increased CLASP2. The LPS-induced STAT3 phosphorylation, NLRP3 inflammasome and IL-1 beta production in NHEKs were statistically counterbalanced by MBSP, suggesting that MBSP displays potent JAK2 inhibition in NHEKs. A significant increase in wound healing at 72 hours was observed on scratched monolayer of NHEKs in the presence of MBSP.
Discussion & Conclusion: As the skin surface is in direct contact with the external environment, external and internal factors may severely impact microbiome balance and skin health. Both skin protection and wound healing are based on intact epidermal architecture and barrier function. Multiple mechanisms of stem cells and cell adhesion allow the formation of skin tissue with well-defined structure. Studies have shown that CLASP2 plays a critical role in the maintenance of adhesion homeostasis in epidermal stem cells, and may prevent keratinocyte differentiation disorders. CLASP2 has also been described to be essential for the inhibition of the JAK2-STAT3 pathway via SOCS3. JAK2 inhibition reduces STAT3 phosphorylation, decreases the activation of NLRP3 inflammasome, resulting in the downregulation of IL-1 beta expression. The latter is critical for the skin inflammation progression and wound repair via keratinocyte proliferation. Our findings are consistent with the possibility that CLASP2 interact with the JAK2-STAT3 pathway to preserve epidermal architecture and barrier function. JAK2 inhibition also has potential skin neuroprotective effects that require further investigation. The CLASP2 and JAK-STAT pathway interaction may become a novel approach for maintaining skin physical and immune barrier synergy.
Methods: We first investigated the epidermal barrier function. Human primary keratinocytes (NHEKs) were obtained from a mature female donor. Cells were pre-incubated during 24 hours. At the end of the pre-incubation period, CLASP2 protein was quantified in cell lysates. Epidermal stem cells were obtained following the method described by Goodell et al. and were irradiated by UVB (30mJ/cm2). Cell viability has been measured using Alamar blue. C. Acnes lysate at a final concentration of 2.108 UFC was used as lipopolysaccharide (LPS). Cells were then incubated with LPS for 24 hours. At the end of the incubation period, p-STAT3, NLRP3 and IL-1 beta protein levels were measured in cell lysates. In order to evaluate the wound healing effect, a scratch of around 1mm of width has been performed in the NHEKs monolayer culture. The area of the injury at Day 0 and the non-recolonized area at Day 3 were measured by image analysis using the Image J software.
Results: In NHEKs, the CLASP2 synthesis was significantly increased by a Mushroom-Based Skin Protectant (MBSP). The latter significantly protected epidermal stem cells from UVB stress, which coincided with the trend towards increased CLASP2. The LPS-induced STAT3 phosphorylation, NLRP3 inflammasome and IL-1 beta production in NHEKs were statistically counterbalanced by MBSP, suggesting that MBSP displays potent JAK2 inhibition in NHEKs. A significant increase in wound healing at 72 hours was observed on scratched monolayer of NHEKs in the presence of MBSP.
Discussion & Conclusion: As the skin surface is in direct contact with the external environment, external and internal factors may severely impact microbiome balance and skin health. Both skin protection and wound healing are based on intact epidermal architecture and barrier function. Multiple mechanisms of stem cells and cell adhesion allow the formation of skin tissue with well-defined structure. Studies have shown that CLASP2 plays a critical role in the maintenance of adhesion homeostasis in epidermal stem cells, and may prevent keratinocyte differentiation disorders. CLASP2 has also been described to be essential for the inhibition of the JAK2-STAT3 pathway via SOCS3. JAK2 inhibition reduces STAT3 phosphorylation, decreases the activation of NLRP3 inflammasome, resulting in the downregulation of IL-1 beta expression. The latter is critical for the skin inflammation progression and wound repair via keratinocyte proliferation. Our findings are consistent with the possibility that CLASP2 interact with the JAK2-STAT3 pathway to preserve epidermal architecture and barrier function. JAK2 inhibition also has potential skin neuroprotective effects that require further investigation. The CLASP2 and JAK-STAT pathway interaction may become a novel approach for maintaining skin physical and immune barrier synergy.