Induction of toll-like receptors by Propionibacterium acnes

BACKGROUND: The bacterium Propionibacterium acnes is involved in the induction and maintenance of the inflammatory phase of acne. Recent studies have found that keratinocytes express toll-like receptors (TLRs) implicated in immediate immunity. No studies have, to date, been carried out on the action of P. acnes upon TLR activation in keratinocytes. OBJECTIVES: Focusing on the inflammatory phase of acne, to clarify the role of P. acnes in immediate immunity by inducing expression of TLR-2 and TLR-4 by keratinocytes. We also studied how the secretion and expression of matrix metalloproteinase (MMP)-9 is induced by P. acnes. METHODS: The work was carried out on two levels: in vivo with the study of the expression of TLR-2 and TLR-4 proteins in biopsies of acne lesions and in vitro on cultured keratinocyte monolayers to study the modulating effects of P. acnes on the expression of TLR-2 and TLR-4 and also on the expression and secretion of MMP-9. RESULTS: Our findings reveal that in vivo TLR-2 and TLR-4 expression is increased in the epidermis of acne lesions. In vitro, an increase in TLR-2 and TLR-4 expression by human keratinocytes occurred in the first hours of incubation with bacterial fractions as well as an increase of the expression and secretion by the keratinocytes of MMP-9, which plays a role in inflammation. CONCLUSIONS: This work demonstrates that P. acnes induces TLR expression and that this mechanism could play an essential role in acne-linked inflammation. These receptors could be involved notably in acute acne.     

Activation of Toll-like Receptors 1, 2, 4, 5, and 7 on Human Melanocytes Modulate Pigmentation

Human melanocytes are not simply pigment-producing cells. It may be part of the inflammatory response, during which the pigmentary system may produce more melanin or suppress melanization. Toll-like receptors (TLRs) have been implicated in both innate host defense against pathogens and inflammatory response. Therefore, it may be possible that activation of TLRs in melanocytes may play a role in the modulation of melanogenesis. In this study, we investigated whether normal human melanocytes expressed TLRs and analyzed pigmentation changes upon TLR stimulation. The expression of TLR1~10 mRNA in cultured human melanocyte was analyzed using RT-PCR, Western blotting and immunocytochemistry. Human melanocytes constitutively express mRNA and protein for TLR2, 3, 4, 5, 7, 9 and 10. Stimulation of TLR1/2 and 4 with Pam3CSK4 and lipopolysaccharide induced pigmentation of melanocytes. Activation of TLR5 and 7 with flagellin and imiquimod treatments reduced pigmentation of melanocytes and zebrafish. In summary, the results provided evidence for TLRs expression in normal human melanocytes. It is speculated that a response of melanocyte to TLR ligands may play a role in the pigmentary change in the skin.     

Mapping toll-like receptor activity in different stages of cutaneous T-cell lymphoma

ABSTRACT:: It is known that human keratinocytes (KCs) express Toll-like receptors (TLRs). However, published reports conflict regarding TLR expression in cutaneous T-cell lymphoma patient's KCs. To define the pattern of expression and detect any differences of TLRs 1-9 and p65 expression in epidermal KCs, tumor infiltrate, and endothelial cell types using immunohistochemical stains on fixed and paraffin-embedded sections of mycosis fungoides (MF) in patch, plaque, and nodular stages. MF cases showed no change in pattern of TLRs expressed through different stages but increased epidermal staining of TLRs 2, 3, 4, 5, 6, and 8 with higher scores associated with more aggressive stages. Endothelial cell staining was increased for TLR 4 and 6. Tumor infiltrate staining was strongest with TLRs 5 and 7. Individual cases with disease progression showed increased intensity of TLRs 4, 5, and 6 staining in the epidermis, tumor infiltrate, and endothelial cell. p65 verified nuclear factor kappa B activation of the TLR pathway with trace staining of the epidermis and 1-2+ staining of tumor infiltrate. MF cases showed increased epidermal expression of TLRs and increased endothelial cell staining compared with controls. TLR expression may be driven by antigenic stimulation and may play a role in the activation of neoplastic T cells in the skin. Further definition of TLR patterns may refine the use of TLR modifiers for treatment.     

Expression of TLR3, 4, 7 and 9 in cutaneous malignant melanoma: relationship with clinicopathological characteristics and prognosis

Toll-like receptors (TLRs) have achieved an extraordinary amount of interest in cancer research due to their role in tumor progression. The aim of this study was to investigate the expression and clinical relevance of TLR3, 4, 7 and 9 in cutaneous malignant melanoma (CMM). The expression levels of TLR3, 4, 7 and 9 were analyzed in tumors from 30 patients with CMM. The analysis was performed by immunohistochemistry, and the results were correlated with various clinicopathological findings and with relapse-free survival. Our results indicate that there was a wide variability in the immunostaining score values for each receptor. Positive staining for TLRs was generally found in tumor cells, especially for TLR4 and TLR9. Nevertheless, a significant percentage of tumors also showed TLR4 expression in mononuclear inflammatory cells (62.1 %) and in fibroblast-like cells (34.5 %). Our results showed no significant association between score values for each TLR and clinicopathological characteristics of patients. However, our results demonstrated that high TLR4 expression was significantly associated with a shortened relapse-free survival (p = 0.001). Therefore, TLR4 expression may be a new prognostic factor of unfavorable evolution in cutaneous malignant melanoma.     

Hyaluronan fragments induce cytokine and metalloprotease upregulation in human melanoma cells in part by signalling via TLR4

Abstract:  Small fragments of the extracellular matrix component hyaluronic acid (sHA) are typically produced at sites of inflammation and tissue injury and have been shown to be associated with tumor invasiveness and metastasis. Here we report that exposure of human melanoma cells to sHA leads to nuclear factor kB (NFk-B) activation followed by enhanced expression of matrix metalloprotease (MMP) 2 and interleukin (IL)-8, factors that can contribute to melanoma progression. At the receptor level, we found that Toll-like receptor (TLR) 4 is involved in this signalling pathway, similar to the case in dendritic and endothelial cells. Specifically, we found that melanoma cells expressed TLR4 on their surface in vivo and in vitro , and using specific siRNA, we could clearly demonstrate the functional importance of TLR4 in sHA-triggered activation of IL-8 expression in melanoma cells. Furthermore, we also found that sHA treatment enhanced the motility of melanoma cells, an effect that could again be blocked by TLR4-specific siRNA. Together, our results suggest that sHA in melanoma might promote tumor invasiveness by inducing MMP- and cytokine-expression, in part in a TLR4-dependent manner, providing new insights into the relationship between cancer and innate immunity.     

Toll样受体在尖锐湿疣皮损中的表达

目的 探讨尖锐湿疣皮损中Toll样受体（TLR）各亚型的表达。方法 将尖锐湿疣患者的病损组织标本冰冻切片经免疫组化染色检测10种TLR亚型的表达情况,以正常皮肤组织作对照,比较两者TLR表达谱的差异。结果 正常表皮角质层和颗粒层TLR6、9呈强阳性表达,TLR1、3、10呈中等强度表达,TLR2、4、5、7、8弱表达,棘层和基底层细胞不表达或弱表达TLR;尖锐湿疣皮损表皮中除基底层弱表达或不表达TLR外,其余细胞层TLR1、3、6、9强阳性表达,TLR4、8、10中等强度表达,TLR2、5、7弱表达。两组皮肤的真皮层均未见明显TLR阳性细胞。结论 尖锐湿疣皮损增生的角质形成细胞中TLR表达较正常皮肤明显增高,尤以TLR1、3、6、9亚型为著,可能与HPV感染启动机体抗病毒免疫有关。     

Expression of functional Toll-like receptor 2 on human epidermal keratinocytes

Epidermal keratinocytes secrete cytokines, chemokines, and anti-microbial peptides in response to various microbial pathogens and their components including lipopolysaccharide (LPS). To identify the receptor(s) involved in the anti-microbial responses of epidermal keratinocytes, we analyzed expression of CD14, Toll-like receptor 2 (TLR2), and TLR4 on cultured normal human epidermal keratinocytes (NHEK). Although CD14 and TLR2 mRNA were expressed in cultured NHEK, only TLR2 was detected on the cell surface. Cultured NHEK did not express TLR4 mRNA or protein. Commercial LPS preparations could stimulate epidermal keratinocytes to produce β-defensin-2 and IL-8, and the LPS response was inhibited with mAb specific for TLR2, but not for CD14 or TLR4. Repurified LPS and lipid A did not stimulate epidermal keratinocytes, whereas peptidoglycan (PGN) from Gram-positive bacteria and yeast cell wall particle induced β-defensin-2 and IL-8 production. Thus, cultured NHEK express functional TLR2, but not CD14 or TLR4, and the “LPS” response of epidermal keratinocytes shown in the previous studies might be mediated by TLR2-dependent recognition of non-LPS bacterial components contaminating in commercial LPS preparations. In the normal human skin, however, epidermal keratinocytes expressed both TLR2 and TLR4. Because TLR4 was induced in epidermal keratinocytes by in vitro stimulation with PGN from Gram-positive bacteria, constitutive expression of TLR4 on epidermal keratinocytes in vivo might also be induced by continuous recognition of the resident skin flora containing Gram-positive bacteria through TLR2.     

2型单纯疱疹病毒对HaCaT细胞表达Toll样受体1～10的影响

目的观察2型单纯疱疹病毒(HSV-2)对人永生化角质形成细胞株(HaCaT)表达Toll样受体(Toll-like receptors,TLRs)1～10的影响,探讨角质形成细胞(keratinocyte cell,KC)对HSV-2病毒感染初期的免疫防御机制。方法采用非洲绿猴肾细胞株VERO细胞进行HSV-2病毒扩增,再用HSV-2病毒感染HaCaT细胞,应用荧光实时定量PCR检测感染后24h,48h和72h时TLR1～10mRNA的表达量。结果静息状态下TLR1～10mRNA在HaCaT细胞中均有表达,经HSV-2病毒感染后HaCaT细胞转录TLR2～4和9mRNA的表达量与对照组相比,均显著升高,差异有统计学意义(P均0.05),而TLR1和7mRNA的表达量与对照组相比,均下降,差异也有统计学意义(P均0.05),TLR5～6,8和10mR-NA的表达量与对照组相比,差异则均无统计学意义(P均0.05)。结论 KC表达TLR1～10,其中TLR2～4和9在HSV-2感染初期对识别及清除病毒并防止其感染扩散有积极的作用,而TLR5～6,8和10在HSV-2病毒感染KC初期可能不起作用。     

MV3恶性黑素瘤皮肤体外模型中基质金属蛋白酶-2、9的表达

目的 探讨体外构建的MV3恶性黑素瘤皮肤模型中基质金属蛋白酶-2（MMP-2）和基质金属蛋白酶-9（MMP-9）的表达及意义。方法 用MV3恶性黑素瘤细胞接种至去表皮的真皮（DED）上,采用液下和空气－液面培养相结合的方式进行组织培养,2周后取培养的黑素瘤组织切片分别做HE染色及MMP-2、9免疫组化染色。同时用RT-PCR对培养组织进行MMP-2、9表达检测。结果 HE染色显示MV3黑素瘤细胞在DED表面呈条带状生长,在凹陷处聚集生长,在DED残留的皮肤附属器管腔中形成大小不等的团、灶;免疫组化染色显示在MV3黑素瘤细胞生长的DED表层及DED附属器管壁基底膜处MMP-2、9均呈阳性表达;RT-PCR检测进一步证实体外构建的恶性黑素瘤组织表达MMP-2和MMP-9,而未接种MV3黑素瘤细胞的DED组织无MMP-2、9表达。结论 体外构建的恶性黑素瘤皮肤模型中瘤细胞侵入到真皮,表达MMP-2、9,为进一步研究黑素瘤的侵袭与转移提供实验依据。     

Normal keratinocytes express Toll-like receptors (TLRs) 1, 2 and 5: modulation of TLR expression in chronic plaque psoriasis

BACKGROUND: Toll-like receptors (TLRs) are part of the innate immune system involved in the response to microbial pathogens. TLR2 recognizes various ligands expressed by Gram-positive bacteria, while TLR3, TLR4 and TLR5 are specific for double-stranded RNA, Gram-negative lipopolysaccharides and bacterial flagellin, respectively. OBJECTIVES: To determine, firstly, whether epidermal keratinocytes of normal skin express TLRs and, secondly, whether modulation of TLR expression occurs in psoriasis, an inflammatory skin disease associated with certain microorganisms such as streptococci, staphylococci and yeasts. METHODS: Eight samples of normal, and 15 samples of lesional and nonlesional psoriatic skin were stained with polyclonal antibodies specific for TLR1-5 using an avidin-biotin-peroxidase technique. RESULTS: Epidermal keratinocytes in normal skin constitutively expressed TLR1, TLR2 and TLR5, while TLR3 and TLR4 were, in most cases, barely detectable. Cytoplasmic TLR1 and TLR2 were expressed throughout the epidermis, with higher staining of the latter on basal keratinocytes, while TLR5 expression was concentrated in the basal layer. In contrast, in lesional epidermis from patients with psoriasis, TLR2 was more highly expressed on the keratinocytes of the upper epidermis than on the basal layer, while TLR5 was downregulated in basal keratinocytes compared with corresponding nonlesional psoriatic epidermis. In addition, nuclear TLR1 staining was observed in the upper layers of both nonlesional and lesional psoriatic epidermis, but not in that of normal skin. CONCLUSIONS: These findings suggest that TLRs expressed by epidermal keratinocytes constitute part of the innate immune system of the skin. The relevance of altered keratinocyte TLR expression in psoriasis remains to be determined.     

Toll样受体2、4 和9在皮肤结核皮损中的表达

目的 研究Toll样受体2、4和9 （TLR-2、TLR-4、TLR-9）在寻常狼疮和疣状皮肤结核皮损中的表达,探讨其在皮肤结核发病中的作用。方法 经临床与病理确诊的皮肤结核（包括寻常狼疮和疣状皮肤结核）患者皮损标本18份,斑块状银屑病皮损15份为阳性对照,色素痣边缘正常皮肤10份为阴性对照。用免疫组化法观察TLR-2、TLR-4、TLR-9的表达情况。采用SPSS 13.0统计软件进行统计学分析,组间比较行t检验。结果 TLR-2在正常皮肤表达于除基底层外的表皮全层,而在皮肤结核和银屑病皮损表达于表皮的中上层,3组的表达强度均为高表达（A值分别为0.28 ± 0.03、0.25 ± 0.04和0.25 ± 0.05）,3组差异无统计学意义（P > 0.05）。TLR-4在正常皮肤和银屑病呈低或无表达（A值分别为0.07 ± 0.09和0.02 ± 0.05）,而皮肤结核（0.16 ± 0.07）呈低表达,其表达强度高于正常皮肤（t = 2.58,P ＜ 0.05）和银屑病皮损（t = 6.24,P ＜ 0.01）。TLR-9在正常皮肤和皮肤结核表达于表皮全层、附属器及血管壁,而皮肤结核的表达强度（A值为0.25 ± 0.05）高于正常皮肤（0.19 ± 0.05）,两组比较,t = 2.88,P ＜ 0.05。结论 TLR-2、TLR-4和TLR-9在皮肤结核皮损中均存在表达,其中TLR-4和TLR-9的表达高于正常皮肤,提示其在皮肤结核的免疫应答中可能起一定的作用。     

Microbial recognition by Toll-like receptors

Toll-like receptors (TLRs) sense invasion of microorganisms by detecting microbial components that are conserved among pathogens. Recognition of microbial components by TLRs triggers activation of the innate immune system. Signaling pathways via TLRs originate from conserved cytoplasmic Toll/IL-1 receptor (TIR) domains. Recent accumulating evidence demonstrates that TIR domain-containing adaptors, such as MyD88, TIRAP/Mal, TRIF, and TRAM, regulate TLR-mediated signaling pathways. MyD88 is common to all TLR-mediated pathways, which lead to the production of inflammatory cytokines, whereas TRIF mediates induction of IFN-beta in TLR3 and TLR4 signaling pathways. TIRAP/Mal is implicated in the TLR2- and TLR4-mediated MyD88-dependent signaling pathway. TRAM is specifically involved in the TLR4-mediated TRIF-dependent pathway. Thus, TIR domain-containing adaptors play a pivotal role in TLR signaling pathways, which culminate in pathogen-specific immune responses.     

Human keratinocytes express functional Toll-like receptor 3, 4, 5, and 9

Keratinocytes are continuously in contact with external stimuli and have the capacity to produce several soluble mediators. Pathogen-associated molecular patterns (PAMPs) are recognized, among others, by Toll-like receptors (TLRs). The functional responses of keratinocytes to different PAMPs have not yet been fully established. Here we show that keratinocytes constitutively express TLR1, 2, 3, 4, 5, 6, 9, and 10 mRNA, but not TLR7 and 8. Stimulation of keratinocytes with TLR3, 4, 5, and 9 ligands resulted in differential immune-associated responses. Tumor necrosis factor-alpha, CXC chemokine ligand 8 (CXCL8), CCL2, and C chemokine ligand 20 (CCL20) release was enhanced in response to all PAMPs tested, in a time- and dose-dependent manner. Only TLR9 ligand CpG-oligodeoxynucleotides (ODNs) and TLR3 ligand poly-I:C could additionally induce type I IFNs. CCL27 production was selectively induced by poly-I:C and flagellin, whereas CXCL9 and CXCL10 were exclusively induced by CpG-ODNs and/or poly-I:C. Upregulation of ICAM-1, HLA-DR, HLA-ABC, FasR, and CD40 was mainly observed in response to poly-I:C, flagellin, and lipopolysaccharide. Furthermore, PAMP triggering resulted in the phosphorylation of phosphorylated-IkappaB alpha and in the nucleus translocation of NF-kappaB p65. Altogether, these findings stress an unexpectedly multifaceted role of keratinocytes in innate immunity as evident by their differential, TLR-mediated responses to PAMPs associated with different classes of pathogens.     

金黄色葡萄球菌肽聚糖对HaCaT细胞Toll样受体2和4的影响

目的观察金黄色葡萄球菌胞壁成分肽聚糖对HaCaT细胞Toll样受体(TLR)2和TLR4表达的影响。方法用不同浓度的肽聚糖(10μg/mL、30μg/mL、100μg/mL)处理培养的HaCaT细胞,用RT-PCR检测TLR2 mRNA和TLR4 mRNA含量变化,用流式细胞术检测HaCaT细胞表面TLR2和TLR4蛋白的表达。结果30μg/mL肽聚糖处理组HaCaT细胞的TLR2 mRNA和TLR4 mRNA相对表达水平分别为0.826±0.06和0.801±0.04,明显高于未处理的对照组的TLR2 mRNA(0.433±0.04,P<0.05)和TLR4 mRNA(0.351±0.05,P<0.01)。各浓度的肽聚糖处理HaCaT细胞24h,及100μg/mL浓度的肽聚糖处理HaCaT细胞12h、24h、36h和48h时,及100μg/mL肽聚糖处理24h后,HaCaT细胞表面TLR2和TLR4蛋白表达量均最高。结论肽聚糖可以上调HaCaT细胞TLR2和TLR4的mRNA和蛋白的表达。     

Toll-like receptors 2, 4 and 9 expression in cutaneous T-cell lymphoma (mycosis fungoides and Sézary syndrome)

The aim of this work was to study Toll-like receptors (TLRs) 2, 4 and 9 expression patterns in parapsoriasis and in cutaneous T-cell lymphoma (CTCL): Mycosis fungoides (MF) and Sézary syndrome (SS) at different stages of the illness. The expression of TLRs was examined by immunohistochemistry on paraffin-embedded biopsies. Normal skin, atopic dermatitis and psoriasis, were used as controls. In cutaneous lesions of inflammatory diseases (atopic dermatitis, psoriasis) the expression of TLR2, TLR4 and TLR9 was low compared to normal skin. In parapsoriasis the expression of the three TLRs was similar to control. By contrast, in MF skin we observed a strong intensity of labelling with the three TLRs in the epidermis. Concerning SS, the expression of TLR2, TLR4 and TLR9 was intermediate between inflammatory lesions and MF. Thus, the development of skin lesions in MF appears associated with an increase of TLR2, TLR4 and TLR9 expression by keratinocytes in cutaneous lesions, which could play a role in the chronic activation of T lymphocytes in the skin.     

CpG motifs are efficient adjuvants for DNA cancer vaccines

DNA vaccines can induce impressive specific cellular immune response (IR) when taking advantage of their recognition as pathogen-associated molecular patterns (PAMP) through Toll-like receptors (TLR) expressed on/in cells of the innate immune system. Among the many types of PAMP, immunostimulatory DNA, so-called CpG motifs, was shown to interact specifically with TLR9, which is expressed in plasmacytoid dendritic cells (pDC), a key regulatory cell for the activation of innate and adaptive IR. We now report that CpG motifs, when introduced into the backbone, are a useful adjuvant for plasmid-based DNA (pDNA) vaccines to induce melanoma antigen-specific protective T cell responses in the Cloudman M3/DBA/2 model. The CpG-enriched pDNA vaccine induced protection against subsequent challenge with melanoma cells at significantly higher levels than its parental unmodified vector. Preferential induction of an antigen-specific, protective T cell response could be demonstrated by (i) induction of antigen-dependent tumor cell protection, (ii) complete loss of protection by in vivo CD4+/CD8+T cell- but not NK cell-depletion, and (iii) the detection of antigen-specific T cell responses but not of relevant NK cell activity in vitro. These results demonstrate that employing PAMP in pDNA vaccines improves the induction of protective, antigen-specific, T cell-mediated IR.     

Tumor microenvironment modulates hyaluronan expression: the lactate effect

Hyaluronan (HA) synthesis is a tightly regulated process and is partly controlled by the microenvironment (e.g., lactate concentration). Experimental evidence has indicated that the melanoma cells that synthesize large amounts of HA exhibit enhanced tumor cell growth and increased metastatic capacity compared to those expressing smaller amounts. Because most studies have examined HA expression on melanoma cells in vitro, we compared the patterns of HA expression by B16-F1 and B16-F10 melanoma cells in vitro and in situ. Cell surface HA expression was assessed with the HA-binding peptide Pep-1. B16-F1 melanoma cells showed significantly higher levels of Pep-1 binding compared with B16-F10 cells in vitro. On the other hand, expression levels of HA were comparable between B16-F1 and B16-F10 melanoma cells in cryostat sections. These results show that B16-F1 cells express high levels of HA in vitro and in vivo, while B16-F10 cells express high concentrations of HA only in the context of skin tumors. Finally, B16-F10 melanoma cells, but not B16-F1 cells, expressed high concentrations of HA after stimulation with lactate. We propose that components of the tumor microenvironment (e.g., lactate) can induce melanoma cells to express HA and thus acquire an aggressive phenotype.     

Expression of Toll-like Receptor 2 in Cultured Human Keratinocytes: The Effect of Bacterial Antigens, Cytokines and Calcium Concentration

Background

Toll-like receptors (TLRs) are expressed by human epidermal keratinocytes and are involved in immune responses.

Objective

The goal of this was to investigate the expression of TLR2 in response to bacterial antigens, cytokines, and different calcium concentrations.

Methods

The expression of TLR2 was assessed after stimulation by lipoteichoic acid (LTA) and streptolysin O (SLO). In addition, TLR2 expression was evaluated after treatment with IFN-γ and TNF-α, and different concentrations of calcium. The expression levels of TLR2 mRNA and protein were studied using RT-PCR and Western blot analysis.

Results

Cultured human epidermal keratinocytes constitutively expressed TLR2 and the expression was stimulated by LTA and SLO; in addition, IFN-γ and TNF-α upregulated TLR2 expression. However, the changes in TLR2 expression associated with the calcium concentrations were insignificant.

Conclusion

TLR2 expression increased with the concentration and duration of bacterial pathogens and this increase was amplified by several cytokines, from activated keratinocytes and other cells.