Zheng Jun Li

Autologous Platelet‐Rich Plasma: A Potential Therapeutic Tool for Promoting Hair Growth

Background Recently, autologous platelet‐rich plasma (PRP) has attracted attention in various medical fields, including plastic and orthopedic surgery and dermatology, for its ability to promote wound healing. PRP has been tested during facelift and hair transplantation to reduce swelling and pain and to increase hair density. Objective To investigate the effects of PRP on hair growth using in vivo and in vitro models. Methods PRP was prepared using the double‐spin method and applied to dermal papilla (DP) cells. The proliferative effect of activated PRP on DP cells was measured. To understand the mechanisms of activated PRP on hair growth, we evaluated signaling pathways. In an in vivo study, mice received subcutaneous injections of activated PRP, and their results were compared with control mice. Results Activated PRP increased the proliferation of DP cells and stimulated extracellular signal‐regulated kinase (ERK) and Akt signaling. Fibroblast growth factor 7 (FGF‐7) and beta‐catenin, which are potent stimuli for hair growth, were upregulated in DP cells. The injection of mice with activated PRP induced faster telogen‐to‐anagen transition than was seen on control mice. Conclusions Although few studies tested the effects of activated PRP on hair growth, this research provides support for possible clinical application of autologous PRP and its secretory factors for promotion of hair growth.

Effect of Wnt signaling pathway on wound healing

Wnt signaling pathway has been divided into two subclasses: the canonical pathway (Wnt/beta-catenin pathway) and the non-canonical pathway. It has been proven that Wnt/beta-catenin pathway can enhance wound healing, and some glycoprotein of Wnt family may directly or indirectly improve wound healing.

Propionibacterium acnes Activates the NLRP3 Inflammasome in Human Sebocytes

Propionibacterium acne and sebaceous glands are considered to have an important role in the development of acne. Although information regarding the activation of innate immunity by P. acnes in the sebaceous gland is limited, different P. acnes phylotypes and a higher prevalence of follicular P. acnes macrocolonies/biofilms in sebaceous follicles of skin biopsies from acne compared with control skin and occasionally single P. acnes clusters in single sebaceous glands have been detected. In this study, we investigated whether P. acnes activates the inflammasome in human sebaceous glands in vivo and in vitro. We found that IL-1β expression was upregulated in sebaceous glands of acne lesions. After stimulation of human sebocytes with P. acnes, the activation of caspase-1 and secretion of IL-1β were enhanced significantly. Moreover, knocking down the expression of NLRP3 abolished P. acnes-induced IL-1β production in sebocytes. The activation of the NLRP3 inflammasome by P. acnes was dependent on protease activity and reactive oxygen species generation. Finally, we found that NALP3-deficient mice display an impaired inflammatory response to P. acnes. These results suggest that human sebocytes are important immunocompetent cells that induce the NLRP3 inflammasome, and that P. acnes-induced IL-1β activation in sebaceous glands may have a role in combating skin infections and in acne pathogenesis.

Regulation of lipid production by acetylcholine signalling in human sebaceous glands

BACKGROUND The extraneuronal cholinergic system has been implicated in numerous functions in the skin, such as terminal differentiation, barrier formation, sweat secretion and the microcirculation. However, the evidence for cholinergic signalling in sebaceous glands is lacking, and its role needs to be clarified. OBJECTIVE We investigated the role of acetylcholine signalling in sebaceous glands using human sebocytes and a clinical study using botulinum toxin. METHODS Immunohistochemistry and immunocytofluorescence were performed to evaluate cholinergic receptor levels in sebaceous glands. Lipid levels were assessed by Oil Red O staining and signalling pathways by Western blotting. To evaluate the clinical relevance, we also assessed the effect of botulinum toxin on sebum production in healthy volunteers. RESULTS We demonstrated that human skin sebaceous glands in vivo and sebocytes in vitro express nicotinic acetylcholine receptor α7 (nAchRα7), and that acetylcholine increased lipid synthesis in a dose-dependent manner. When sebocytes were incubated with α-bungarotoxin, a competitive nAchR antagonist, acetylcholine failed to up-regulate lipid synthesis. Twenty healthy volunteers were enrolled in a double-blind, placebo-controlled, split-face study. A marked decrease in sebum production on the botulinum-treated side was found in volunteers with oily skin. CONCLUSION These results provide evidence that acetylcholine signalling plays a significant role in human sebaceous gland biology and identify acetylcholine signalling as a promising target in the clinical management of disorders in which sebum production is increased, such as acne vulgaris.

Roles of TLR7 in Activation of NF-κB Signaling of Keratinocytes by Imiquimod

Imiquimod is known to exert its effects through Toll-like receptor 7 (TLR7) and/or TLR8, resulting in expression of proinflammatory cytokines and chemokines. Keratinocytes have not been reported to constitutively express TLR7 and TLR8, and the action of imiquimod is thought to be mediated by the adenine receptor, not TLR7 or TLR8. In this study, we revealed the expression of TLR7 in keratinocytes after calcium-induced differentiation. After addition of calcium to cultured keratinocytes, the immunological responses induced by imiquimod, such as activation of NF-κB and induction of TNF-α and IL-8, were more rapid and stronger. In addition, imiquimod induced the expression TLR7, and acted synergistically with calcium to induce proinflammatory cytokines. We confirmed that the responses induced by imiquimod were significantly inhibited by microRNAs suppressing TLR7 expression. These results suggest that TLR7 expressed in keratinocytes play key roles in the activation of NF-κB signaling by imiquimod, and that their modulation in keratinocytes could provide therapeutic potential for many inflammatory skin diseases.

Imiquimod Induces Apoptosis of Squamous Cell Carcinoma (SCC) Cells via Regulation of A20

Imiquimod, a nucleoside analogue of the imidazoquinoline family, is being used to treat various cutaneous cancers including squamous cell carcinoma (SCC). Imiquimod activates anti-tumor immunity via Toll-like receptor 7 (TLR7) in macrophage and other immune cells. Imiquimod can also affect tumor cells directly, regardless of its impact on immune system. In this study, we demonstrated that imiquimod induced apoptosis of SCC cells (SCC12) and A20 was involved in this process. When A20 was overexpressed, imiquimod-induced apoptosis was markedly inhibited. Conversely, knockdown of A20 potentiated imiquimod-induced apoptosis. Interestingly, A20 counteracted activation of c-Jun N-terminal kinase (JNK), suggesting that A20-regulated JNK activity was possible mechanism underlying imiquimod-induced apoptosis of SCC12 cells. Finally, imiquimod-induced apoptosis of SCC12 cells was taken place in a TLR7-independent manner. Our data provide new insight into the mechanism underlying imiquimod effect in cutaneous cancer treatment.

Regional difference in sebum production by androgen susceptibility in human facial skin

Androgens are important hormones that influence sebum production from the sebaceous glands. Human facial skin can be categorized as T‐ and U‐zones, which are areas with high and low levels of sebum secretion, respectively. This study was performed to investigate whether there are topographical differences in androgen receptor (AR) expression related to regional variations in facial sebum secretion. The results of in vivo analysis indicated a statistically significant increase in AR expression in the sebaceous gland T‐zones compared with the U‐zones. In vitro experiments using human primary sebocytes also yielded similar results, with higher levels of AR protein and mRNA expression in T‐zones. The results of this study suggested that differences in androgen susceptibility may be an important factor influencing regional differences in sebum production in human facial skin.

Clinicopathological roles of S100A8 and S100A9 in cutaneous squamous cell carcinoma in vivo and in vitro.

S100A8 and S100A9 are members of the S100 protein family and exist in neutrophils, monocytes, and macrophages. Recent studies have shown that S100A8 and S100A9 are associated with various neoplastic disorders; however, their roles in cutaneous squamous cell carcinoma (SCC) are not well defined. To investigate the expression and function of S100A8 and S100A9 in skin tumors, we examined the expression levels of S100A8 and S100A9 between premalignant and malignant skin tumors and investigated the functional roles of S100A8 and S100A9 in vitro and in vivo using recombinant adenovirus expressing S100A8 or S100A9. The immunopositive staining rates and intensities of S100A8 and S100A9 were higher in SCC than in premalignant skin tumors. When S100A8 and/or S100A9 were overexpressed in SCC12 cells using a recombinant adenovirus, cell growth and motility were increased. Similarly, when mouse skin was intradermally injected with SCC12 cells overexpressing S100A8 and/or S100A9, there were remarkable increases in tumor growth and volume. Both S100A8 and S100A9 are highly expressed in cutaneous SCC and play important roles in tumorigenesis. We suggest that S100A8 and S100A9 may be potential therapeutic targets for the prevention or treatment of SCC in skin.

Genkwadaphnin induces reactive oxygen species (ROS)-mediated apoptosis of squamous cell carcinoma (SCC) cells

Genkwadaphnin is a daphnane diterpene ester molecule isolated from the flower buds of Daphne genkwa. In the present study, we investigated the apoptosis-inducing effect of genkwadaphnin in squamous cell carcinoma (SCC) cells. Apoptosis was triggered in SCC12 cells following genkwadaphnin treatment in a time- and concentration-dependent manner. Genkwadaphnin treatment increased phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Knockdown of JNK and p38 MAPK by recombinant adenovirus expressing microRNA (miR) resulted in significant inhibition of genkwadaphnin-induced apoptosis in SCC12 cells. Finally, pretreatment with the reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) markedly reduced SCC12 cell apoptosis, concomitant with significant inhibition of MAPK activation. These results indicate that genkwadaphnin has the potential to induce apoptosis in SCC cells, providing information on which to base further research with the aim of developing a cure for SCC.

Inhibitory effect of cucurbitacin B on imiquimod-induced skin inflammation

Psoriasis is a common skin disease, of which pathogenesis involves the increase of inflammatory reaction in epidermal cells. In an attempt to find therapeutics for psoriasis, we found that cucurbitacin B has an inhibitory potential on imiquimod-induced inflammation of keratinocytes. Cucurbitacin B significantly inhibited imiquimod-induced expression of crucial psoriatic cytokines, such as IL-8 and CCL20, via down-regulation of NF-κB and STAT3 signaling pathway in human keratinocytes. In addition, keratinocyte proliferation was markedly inhibited by cucurbitacin B. The potential beneficial effect of cucurbitacin B on psoriasis was further validated in imiquimod-induced psoriasiform dermatitis of experimental animal. Topical application of cucurbitacin B resulted in significant reduction of epidermal hyperplasia and inflammatory cytokines production, and ameliorated the psoriatic symptom. Taken together, these results suggest that cucurbitacin B may be a potential candidate for the treatment of psoriasis.