TOLL样受体在皮肤中的表达和功能

Toll样受体在皮肤角质形成细胞、树突状细胞、成纤维细胞和肥大细胞中都有表达,但表达的种类有明显区别.不同细胞的同一Toll受体激活后引起的反应亦有所不同.Toll样受体与其相应的配体结合可以诱导细胞产生多种炎症因子和抗菌肽,在皮肤介导的固有免疫和炎症反应中有重要作用.     

免疫炎症在皮肤创伤中的作用及研究进展

组织损伤后出现炎症反应不可避免。越来越多的证据显示炎症反应在皮肤损伤后内稳态的重建中至关重要,并且特异性的炎性细胞亚群及其分泌的细胞因子相互作用形成的网络直接影响角质形成细胞的增殖,进而影响组织修复。近年来发现皮肤中过度的炎症反应会延迟创伤愈合,而在创伤微环境作用下皮肤的角质形成细胞亦会加重炎症反应。因此深入了解组织修复时控制炎症反应的机制以及炎症反应怎样直接影响愈合过程非常重要。本文将对近期皮肤组织修复时控制炎症反应潜在的细胞及分子机制作一简要综述。     

皮肤抗菌肽的研究进展

抗菌肽是机体固有免疫的重要组成部分,人类皮肤抗菌肽主要包括cathelicidins家族和β-防御素家族,广泛表达于皮肤角质形成细胞及各种炎症细胞.皮肤抗菌肽除了直接杀菌作用外,还能调节免疫反应,促进伤口愈合和血管新生,其表达受到体内,体外多种因素的影响,与各种皮肤炎症性疾病发病密切相关,也可能在糖尿病创面愈合中发挥着重要作用.     

小鼠皮肤角质细胞在电场中的移动及其机理的研究

研究小鼠皮肤角质细胞在电场中的移动以及微管、微丝和钙离子通道在细胞移动中的作用.制作直流电场干预细胞装置,以不同强度的电流作用于小鼠皮肤角质细胞,并在培养基中加入L-型钙离子通道阻断剂硝苯地平、微管抑制剂秋水仙碱和微丝抑制剂细胞松弛素B观察小鼠皮肤角质细胞运动的变化.结果表明:小鼠皮肤角质细胞在1.6 mA电流刺激下向阴极方向移动,移动速率为29.966 μm/h.加入硝苯地平,对小鼠皮肤角质细胞移动的抑制作用不明显.而秋水仙碱和细胞松弛素B对小鼠皮肤角质细胞移动有明显抑制作用.小鼠皮肤角质细胞在电场中可以向阴极定向移动,微管和微丝参与调解这一运动,而L-型钙离子通道与此运动无关.     

低温治疗通过p38 MAPK信号通路抑制UVB诱导的小鼠皮肤炎症北大核心CSCD

目的探讨局部低温治疗对中波紫外线辐射(UVB)诱导的皮肤炎症的作用机制。方法角质形成细胞体外培养后接受如下3种处理:仅低温治疗、仅UVB照射、UVB照射后低温治疗,检测低温治疗对UVB照射后角质形成细胞的作用。将野生型雌性C57BL/6小鼠分为3组:低温治疗组、UVB组、UVB+低温治疗组。通过数字测微计测量、组织病理学、免疫组织化学、免疫荧光、定量RT-PCR和Western blot检测低温治疗对UVB诱导炎症的影响。结果低温治疗可显著减少UVB诱导的巨噬细胞和T细胞浸润(P<0.05),并显著抑制UVB诱导的p38磷酸化(P<0.05),减少相关的炎症反应,包括减轻耳肿胀反应、表皮增生(P<0.05)和皮肤炎症(P<0.05),减少小鼠模型中相关细胞因子表达和细胞凋亡(P<0.05)。结论低温治疗是治疗UVB诱导的皮肤炎症的一种有效的方法。     

皮肤共生菌的研究进展

皮肤共生菌是皮肤固有免疫的重要组成部分。它们产生的抗菌肽可增强角质形成细胞生成抗菌肽的作用,并通过抑制表皮损伤后过量炎症因子的释放来维持体内炎症的平衡。研究证实,异位性皮炎、银屑病、痤疮等皮肤疾病的发病及慢性创面的延迟愈合与皮肤共生菌紊乱有关,而皮肤共生菌的深层理解为皮肤疾病提供了新的治疗方式。     

组胺对皮肤肿瘤坏死因子受体分布的影响的实验研究

目的　探讨人皮肤角质细胞TNFR的分布和炎症介质组胺对其分布的影响。方法　依据Tel lides成熟实验模型 ,将人皮肤移植于免疫缺陷小鼠上 ,分别注入等量 10ml组胺或生理盐水 ,然后制成共聚焦荧光显微镜和电镜标本观察。结果　正常皮肤TNFR2阳性反应细胞较少 ,TNFR1阴性细胞数量较多 ,阳性反应主要见于角质细胞的胞质和膜 ;组胺刺激后角质细胞质和膜的TNFR1消失 ,主要分布在角质细胞间隙。结论　组胺可使角质细胞质和膜上TNFR1消失 ,移位于细胞间隙     

角质细胞、混合皮肤移植和免疫调节

1 皮肤相关淋巴细胞(SALT):皮肤免疫系统面临概念的更新1.1 SALT只包括真皮→真皮、表皮同时涉及;1.2 表皮中免疫细胞为郎罕细胞→同时包括郎罕细胞(Lhc)、角质细胞(Kc)和T细胞;1.3 皮肤免疫应答由Lhc捕获抗原至引流淋巴结激活T细胞→T细胞可以同时在表皮和真皮中被激活;1.4 角质细胞主要参与炎症反应发挥屏障作用→可直接参与T细胞激活.但同种异体移植中Kc对T如何发挥作用未明?分泌细胞因子、趋化T细胞因子?直接刺激?递呈抗原?免疫调节?     

角质形成细胞在银屑病中作用的研究进展

银屑病是慢性复发性皮肤疾病,其发生与免疫功能失调、环境因素、信号转导通路紊乱及银屑病易感基因相关。既往研究表明角质形成细胞(KC)在银屑病的发生发展中发挥重要作用。银屑病中KC如何影响炎症细胞的募集、活化,及炎症因子如何导致炎症级联放大尚不明确。KC作为银屑病治疗的靶标,具有广泛的应用前景。本文从银屑病中KC的屏障功能、增殖分化及角质形成细胞与免疫细胞的相互作用作综述。     

组织工程皮肤移植过程中白细胞介素10和肿瘤坏死因子α的表达

背景:白细胞介素10和肿瘤坏死因子α在异体异种皮肤移植局部免疫与排斥反应中发挥了重要作用。但在组织工程人工皮肤移植过程中局部皮肤组织内白细胞介素10和肿瘤坏死因子α的表达情况目前尚不清楚。目的:采用表皮干细胞联合脱细胞真皮构建人工皮肤并移植修复兔全层皮肤缺损创面,观察创面修复效果和局部皮肤组织白介素10与肿瘤坏死因子α的表达变化。方法:将体外培养的人表皮干细胞或角质细胞接种到脱细胞真皮支架中,构建组织工程人工皮肤;取新西兰白兔常规制作背部全层皮肤缺损创面随机分为4组,表皮干细胞组、角质细胞组用含表皮干细胞或角质细胞的组织工程皮肤移植于皮肤缺损创面;脱细胞真皮组移植单纯脱细胞真皮;对照组创面空置。观察创面修复情况,局部炎症反应,创面愈合时间。各组分别于术后7d在部分创面取材观察组织形态和白细胞介素10与肿瘤坏死因子α表达。结果与结论:含表皮干细胞的人工皮肤移植后创面愈合良好,局部炎症反应轻微,无出血、积脓、坏死,创面愈合时间较角质细胞组明显缩短。白细胞介素10在各组均有表达,其中表皮干细胞组表达最强,角质细胞组次之,脱细胞真皮组和对照组最弱。肿瘤坏死因子α在各组也均有表达,其中角质细胞组表达最强,表皮干细胞组次之,脱细胞真皮组和对照组较弱。说明以表皮干细胞作为种子细胞联合脱细胞真皮构建人工皮肤可用有效促进皮肤缺损创面的修复治疗,创面修复过程中局部皮肤组织内白细胞介素10和肿瘤坏死因子的表达变化可能是其取得较好效果的主要机制之一。     

TRPV3 in keratinocytes transmits temperature information to sensory neurons via ATP

Transient receptor potential V3 (TRPV3) and TRPV4 are heat-activated cation channels expressed in keratinocytes. It has been proposed that heat-activation of TRPV3 and/or TRPV4 in the skin may release diffusible molecules which would then activate termini of neighboring dorsal root ganglion (DRG) neurons. Here we show that adenosine triphosphate (ATP) is such a candidate molecule released from keratinocytes upon heating in the co-culture systems. Using TRPV1-deficient DRG neurons, we found that increase in cytosolic Ca²⁺-concentration in DRG neurons upon heating was observed only when neurons were co-cultured with keratinocytes, and this increase was blocked by P2 purinoreceptor antagonists, PPADS and suramin. In a co-culture of keratinocytes with HEK293 cells (transfected with P2X₂ cDNA to serve as a bio-sensor), we observed that heat-activated keratinocytes secretes ATP, and that ATP release is compromised in keratinocytes from TRPV3-deficient mice. This study provides evidence that ATP is a messenger molecule for mainly TRPV3-mediated thermotransduction in skin.     

Importance of transient receptor potential vanilloid 4 (TRPV4) in epidermal barrier function in human skin keratinocytes

The state of the skin changes drastically depending on the ambient temperature. Skin epidermal keratinocytes express thermosensitive transient receptor potential vanilloid (TRPV) cation channels, TRPV3 and TRPV4. These multimodal receptors are activated by various kinds of chemical and physical stimuli, including warm temperatures (>30°C). It has been suggested that TRPV4 is involved in cell–cell junction maturation; however, the effect of temperature fluctuations on TRPV4-dependent barrier homeostasis is unclear. In the present study, we demonstrated that activation of TRPV4 was crucial for barrier formation and recovery, both of which were critical for the prevention of excess dehydration of human skin keratinocytes. TRPV4 activation by physiological skin temperature (33°C), GSK1016790A or 4α-PDD allowed influx of Ca²⁺ from extracellular spaces which promoted cell–cell junction development. These changes resulted in augmentation of intercellular barrier integrity in vitro and ex vivo. TRPV4 disruption reduced the increase in trans-epidermal resistance and increased intercellular permeation after a Ca²⁺ switch. Furthermore, barrier recovery after the disruption of the stratum corneum was accelerated by the activation of TRPV4 either by warm temperature or a chemical activator. Our results suggest that physiological skin temperatures play important roles in cell–cell junction and skin barrier homeostasis through TRPV4 activation.     

A hot new twist to hair biology: involvement of vanilloid receptor-1 (VR1/TRPV1) signaling in human hair growth control

The vanilloid receptor-1 (VR1, or transient receptor potential vanilloid-1 receptor, TRPV1) is activated by capsaicin, the key ingredient of hot peppers. TRPV1 was originally described on sensory neurons as a central integrator of various nociceptive stimuli. However, several human skin cell populations are also now recognized to express TRPV1, but with unknown function. Exploiting the human hair follicle (HF) as a prototypic epithelial-mesenchymal interaction system, we have characterized the HF expression of TRPV1 in situ and have examined TRPV1 signaling in organ-cultured human scalp HF and outer root sheath (ORS) keratinocytes in vitro. TRPV1 immunoreactivity was confined to distinct epithelial compartments of the human HF, mainly to the ORS and hair matrix. In organ culture, TRPV1 activation by capsaicin resulted in a dose-dependent and TRPV1-specific inhibition of hair shaft elongation, suppression of proliferation, induction of apoptosis, premature HF regression (catagen), and up-regulation of intrafollicular transforming growth factor-beta(2). Cultured human ORS keratinocytes also expressed functional TRPV1, whose stimulation inhibited proliferation, induced apoptosis, elevated intracellular calcium concentration, up-regulated known endogenous hair growth inhibitors (interleukin-1beta, transforming growth factor-beta(2)), and down-regulated known hair growth promoters (hepatocyte growth factor, insulin-like growth factor-I, stem cell factor). These findings strongly support TRPV1 as a significant novel player in human hair growth control, underscore the physiological importance of TRPV1 in human skin beyond nociception, and identify TRPV1 as a promising, novel target for pharmacological manipulations of epithelial growth disorders.     

Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels

Carvacrol, eugenol and thymol are major components of plants such as oregano, savory, clove and thyme. When applied to the tongue, these flavors elicit a warm sensation. They are also known to be skin sensitizers and allergens. The transient receptor potential channel (TRPV3) is a warm-sensitive Ca2+-permeable cation channel highly expressed in the skin, tongue and nose. Here we show that TRPV3 is strongly activated and sensitized by carvacrol, thymol and eugenol. Tongue and skin epithelial cells respond to carvacrol and eugenol with an increase in intracellular Ca2+ levels. We also show that this TRPV3 activity is strongly potentiated by phospholipase C-linked, G protein-coupled receptor stimulation. In addition, carvacrol activates and rapidly desensitizes TRPA1, which may explain the pungency of oregano. Our results support a role for temperature-sensitive TRP channels in chemesthesis in oral and nasal epithelium and suggest that TRPV3 may be a molecular target of plant-derived skin sensitizers.     

Epidermal transient receptor potential vanilloid 1 in idiopathic small nerve fibre disease, diabetic neuropathy and healthy human subjects

AIMS: The transient receptor potential vanilloid 1 (TRPV1) plays an important role in mediating pain and heat. In painful neuropathies, intraepidermal TRPV1 nerve fibre expression is low or absent, suggesting that pain generated is not directly related to sensory nerve fibres. Recent evidence suggests that keratinocytes may act as thermal receptors via TRPV1. The aim was to investigate epidermal TRPV1 expression in patients with neuropathic conditions associated with pain. METHODS AND RESULTS: In a prospective study of distal small nerve fibre neuropathy (DISN; n = 13) and diabetic neuropathy (DN; n = 12) intraepidermal nerve fibre density was assessed using the pan axonal marker PGP 9.5 and epidermal TPVR1 immunoreactivity compared with controls (n = 9). Intraepidermal nerve fibres failed to show TRPV1 immunoreactivity across all groups. There was moderate and strong TRPV1 reactivity of epidermal keratinocytes in 41.8% and 6% for DISN, 32.9% and 2.9% for DN and 25.4% and 5.1% for controls, respectively. Moderate keratinocyte TRPV1 expression was significantly increased in DISN compared with controls (P = 0.01). CONCLUSION: Our study suggests that in human painful neuropathies, epidermal TRPV1 expression is mainly in keratinocytes.     

TRPV1 expression in acupuncture points: response to electroacupuncture stimulation

The present study was to examine the distribution of transient receptor potential vanilloid type-1 (TRPV1) receptor immunoreactivity in the acupuncture points (acupoint), and determine the influences of electroacupuncture (EA) stimulation on TRPV1 expression. EA stimulation of BL 40 was conducted in two sessions of 20 min separated by an 80 min interval in anesthetized rats. Sections of skin containing BL 40, and its non-meridian control were examined by immunolabeling with antibodies directed against TRPV1. Without EA, the number of subepidermal nerve fibers expressing TRPV1 was higher in the acupoint than in non-acupoint control skin (p<0.01). The subepidermal nerve fibers showed the co-localization of TRPV1 with peripherine, a marker for the C-fibers and A-δ fibers. The expression of TRPV1 in nerve fibers is significantly increased by EA stimulation in acupoints (p<0.01). However the upregulation in the non acupoint meridian and the non-meridian control skin was short of statistical significance. Double immunostaining of TRPV1 and neuronal nitric oxide synthase (nNOS) revealed their co-localization in both the subepidermal nerve fibers and in the dermal connective tissue cells. These results show that a high expression of TRPV1 endowed with nNOS in subepidermal nerve fibers exists in the acupoints and the expression is increased by EA. We conclude that the higher expression of TRPV1 in the subepidermal nerve fibers and its upregulation after EA stimulation may play a key role in mediating the transduction of EA signals to the CNS, and its expression in the subepidermal connective tissue cells may play a role in conducting the local effect of the EA.     

Kv7/M-type potassium channels in rat skin keratinocytes

Skin keratinocytes fulfil important signalling and protective functions. Immunocytochemical experiments revealed the unexpected presence of immunoreactivity for the M-type potassium channel subunit Kv7.2 in the keratinocyte layer of intact rat paw skin and in keratinocytes isolated from the skin of 1-day-old rats and cultured in vitro for 3–10 days. Application of the M-channel enhancer retigabine (3–10 μM) to isolated cultured rat keratinocytes: (a) increased outward membrane currents recorded under voltage clamp, (b) produced ~3 mV hyperpolarization at rest, (c) enhanced ~3-fold the release of ATP induced by the TRPV3 agonist carvacrol (1 mM) and (d) increased the amplitude of the carvacrol-induced intracellular Ca²⁺ transient measured with Fura-2. The effect of retigabine on ATP release was prevented by the M-channel blocking agent XE991. We conclude that rat skin keratinocytes possess M-channels that, when activated, can modify their physiological properties, with potential significance for their sensory and other biological functions.     

The TRPV1/2/3 activator 2-aminoethoxydiphenyl borate sensitizes native nociceptive neurons to heat in wildtype but not TRPV1 deficient mice

TRPV1 gene disruption results in a loss of capsaicin and proton responsiveness, but has minimal effects on heat-induced nocifensive behavior, suggesting that sensory transduction of heat is independent of TRPV1. TRPV3, another heat-activated ion channel but insensitive to capsaicin, was shown to be expressed in keratinocytes as well as in sensory neurons projecting to the skin. Recently, 2-aminoethoxydiphenyl borate was introduced as a TRPV3 agonist, but its selectivity was questioned by showing that it activated recombinant TRPV1 and TRPV2 as well. We used the isolated mouse skin-saphenous nerve preparation and whole-cell patch-clamping of cultured dorsal root ganglia neurons from TRPV1-/- and wildtype mice. We found no phenotypic differences between the heat responses of polymodal C-fibers, whereas cultured dorsal root ganglia neurons of TRPV1-/- hardly showed any heat-activated currents. Only C-fibers of wildtype but not TRPV1-/- mice were clearly sensitized to heat by 2-aminoethoxydiphenyl borate 10 and 100 microM; heat-activated current in wildtype neurons was only facilitated at 100 microM. Noxious heat-induced calcitonin gene-related peptide release showed clear deficits (<50%) in TRPV1 deficient skin, but the stimulated calcitonin gene-related peptide release from the isolated skull dura was unaffected. In both models, 2-aminoethoxydiphenyl borate was able to potentiate the heat response (46 degrees C, 5 min) in a concentration-dependent manner, again, only in wildtype but not TRPV1-/- mice, suggesting that TRPV2/3 are not involved in this sensitization to heat. The results further suggest that TRPV1 is not responsible for the normal heat response of native nociceptors but plays the essential role in thermal sensitization and a prominent one in controlling dermal calcitonin gene-related peptide release, i.e. neurogenic inflammation.     

Transient receptor potential vanilloid 1 (TRPV1), TRPV4, and the kidney

Recent preclinical data indicate that activators of transient receptor potential channels of the vanilloid receptor subtype 1 (TRPV1) may improve the outcome of ischaemic acute kidney injury (AKI). The underlying mechanisms are unclear, but may involve TRPV1 channels in dorsal root ganglion neurones that innervate the kidney. Recent data identified TRPV4, together with TRPV1, to serve as major calcium influx channels in endothelial cells. In these cells, gating of individual TRPV4 channels within a four‐channel cluster provides elementary calcium influx (calcium sparklets) to open calcium‐activated potassium channels and promote vasodilation. The TRPV receptors can also form heteromers that exhibit unique conductance and gating properties, further increasing their spatio‐functional diversity. This review summarizes data on electrophysiological properties of TRPV1/4 and their modulation by endogenous channel agonists such as 20‐HETE, phospholipase C and phosphatidylinositide 3‐kinase (PI3 kinase). We review important roles of TRPV1 and TRPV4 in kidney physiology and renal ischaemia reperfusion injury; further studies are warranted to address renoprotective mechanism of vanilloid receptors in ischaemic AKI including the role of the capsaicin receptor TRPV1 in primary sensory nerves and/or endothelium. Particular attention should be paid to understand the kidneys' ability to respond to ischaemic stimuli after catheter‐based renal denervation therapy in man, whereas the discovery of novel pharmacological TRPV modulators may be a successful strategy for better treatment of acute or chronic kidney failure.