Human dendritic cell subsets display distinct interactions with the pathogenic mould Aspergillus fumigatus

The mould Aspergillus fumigatus is primarily an opportunistic pathogen of immunocompromised patients. Once fungal spores have been inhaled they encounter cells of the innate immune system, which include dendritic cells (DCs). DCs are the key antigen-presenting cells of the immune system and distinct subtypes, which differ in terms of origin, morphology and function.This study has systematically compared the interactions between A. fumigatus and myeloid DCs (mDCs), plasmacytoid DCs (pDCs) and monocyte-derived DCs (moDCs). Analyses were performed by time-lapse video microscopy, scanning electron microscopy, plating assays, flow cytometry, 25-plex ELISA and transwell assays.The three subsets of DCs displayed distinct responses to the fungus with mDCs and moDCs showing the greatest similarities. mDCs and moDCs both produced rough convolutions and occasionally phagocytic cups upon exposure to A. fumigatus whereas pDCs maintained a smooth appearance. Both mDCs and moDCs phagocytosed conidia and germ tubes, while pDCs did not phagocytose any fungi. Analysis of cytokine release and maturation markers revealed specific differences in pro- and anti-inflammatory patterns between the different DC subsets.These distinct characteristics between the DC subsets highlight their differences and suggest specific roles of moDCs, mDCs and pDCs during their interaction with A. fumigatus in vivo.     

Longitudinal alteration of circulating dendritic cell subsets and its correlation with steroid treatment in patients with severe acute respiratory syndrome

In this study, we found that 74 patients with severe acute respiratory syndrome (SARS) exhibited a rapid, dramatic decrease in numbers of circulating myeloid and plasmacytoid dendritic cells (mDCs and pDCs) during the first 2 weeks of illness (5.3- and 28.4-fold reductions for mDCs and pDCs compared with 25 healthy individuals, respectively), with slow return to normal cell numbers during convalescence (weeks 5–7 of illness on average). In addition, numbers of circulating CD4 and CD8 T cells exhibited milder reductions (2.1- and 1.8-fold at week 1) and earlier return to normal at a mean of weeks 3 and 4, respectively. A significant inverse correlation was found between numbers of DC and T-cell subsets and high-dose steroid treatment. Our novel findings thus suggest that the acute SARS-coronavirus infection probably contributes to the initial reduction of DC and T-cell subsets in blood, and that high-dose steroid administration may subsequently exacerbate and prolong low expression of the cell subsets. These findings will aid the framing of further studies of the immunopathogenesis of SARS.     

皮肤树突状细胞亚群研究进展

皮肤树突状细胞(DC)作为重要的抗原提呈细胞,在机体免疫应答或自身耐受的发生中扮演着非常重要的角色.皮肤免疫系统中定居着多种DC亚群,主要包括表皮层中的郎格汉斯细胞(LC)与真皮层中的各种真皮DC亚群.健康皮肤中的DC亚群主要有表皮LC、真皮DC(dDC)和浆细胞DC(pDC),dDC又分为Langerin+ dDC及Langerin-dDC等.但在炎症性皮肤,如过敏性皮炎、银屑病等病变皮肤中则存在着炎症性DC亚群.DC由于其复杂的异质性群体,导致了其各亚群的特殊化功能.皮肤DC亚群的特殊化功能,为皮肤性疾病的临床治疗及新型疫苗的研发设计等都提供了良好的新策略.     

Aberrant composition of the dendritic cell population in hepatic lymph nodes of patients with hepatocellular carcinoma

Patients with hepatocellular carcinoma (HCC) are characterized by a weak T-cell response to their tumor, and chronic carriers of hepatitis B virus or hepatitis C virus have a poor T-cell response against the virus. These inadequate T-cell responses may be due to insufficient activation of the T cells by dendritic cells (DCs). Because lymph nodes (LNs) are the primary site of antigen-specific T-cell activation, we hypothesized that hepatic LNs of patients with HCC and/or chronic viral hepatitis might have aberrant compositions of their DC populations. To address this hypothesis, we enumerated mature myeloid DCs (MDCs) and plasmacytoid DCs (PDCs) in hepatic LNs by quantitative immunohistochemistry. Patients with HCC and chronic viral hepatitis and patients with chronic viral hepatitis without HCC were compared with patients with liver inflammation of nonviral etiology and with organ donors with healthy livers. The numbers of PDCs and mature MDCs in hepatic LNs of patients with chronic viral hepatitis did not differ from those of patients with liver inflammation of nonviral etiology nor from individuals with healthy livers. However, hepatic LNs of patients with HBV or HCV infection complicated by HCC showed a 1.5-fold reduction in numbers of mature MDCs and a 4-fold increase in numbers of PDCs in their T-cell areas compared with those of patients with viral hepatitis only (P <.01). In conclusion, patients with HCC have an aberrant composition of the DC population in their hepatic LNs. This may be one of the causes of the inadequate T-cell response against HCC in these patients.     

Interleukin 17-Producing γδ T Cells Increased in Patients with Active Pulmonary Tuberculosis

Although it has been known that γδ T cells may play an important role in the immune response to infection of Mycobacterium tuberculosis （M. tb）, the mechanisms by which the γδ T cells participate in the innate and/or acquired immunity to tuberculosis （TB） have not been full elucidated. In the present study, 27 patients with active pulmonary TB and 16 healthy donors （HD） were performed. We found that proportion of IL-17-producing cells among lymphocyte was similar between TB patients and HD, whereas the proportions of γδ T cells in IL-17-producing cells （59.2%） and IL-17-producing cells in γδ T cells （19.4%） in peripheral blood were markedly increased in TB patients when compared to those in HD （43.9% and 7.7%, respectively）. In addition, the proportions of IFN-T-producing γδ T cells in TB patients were obviously lower than that in HD. Upon re-stimulated with M. tb heat-treated antigen （M. tb-HAg） in vitro, fewer IL-17-producing γδ T cells were generated from HD and TB patients, whereas IFN-T-producing γδ T cells were increased in TB patients compared to that in HD. Our findings in TB patients and healthy human were consistent with other murine investigation that the IL-17- producing γδ T cells were main source of IL-17 in mouse model of BCG infection, suggesting that γδ T cells might be involved in the formation of tubercular granuloma in pulmonary TB patients, but need further identification.     

结核病患者外周血树突状细胞及其亚群的变化

目的:分析不同结核病患者外周血树突状细胞(DCs)及其亚群的变化,并进行免疫机制探讨。方法:就诊于我院2008-11/2009-08的结核病患者32例(实验组),同期在我院进行健康体检者11例(对照组),采用流式细胞术(FCM)检测了结核病患者(包括19例初治患者和13例复治患者,以及痰涂片结果不同的19例肺结核患者)和对照组中外周血中DCs及其亚群的变化。结果:实验组DC1亚群的比率和DCs的总数分别为(0.28±0.13)%和(0.42±0.19)%,明显低于对照组的DC1亚群的比率和DCs的总数(0.47±0.23)%和(0.65±0.22)%(P0.01)。痰涂片阳性患者外周血中DC1亚群的比率和DCs的总数分别为(0.16±0.04)%和(0.24±0.06)%,明显低于痰涂片阴性患者DC1亚群的比率和DCs的总数(0.28±0.14)%和(0.43±0.12)%(P0.05)。初治患者与复治患者外周血中DCs的总数及其亚群的比率无统计学意义(P0.05)。结论:DCs可作为结核病传染源初筛和抗结核疗效观察的参考指标,反映不同结核病患者的免疫状态。     

Elevated HMGB1-related interleukin-6 is associated with dynamic responses of monocytes in patients with active pulmonary tuberculosis

There were limited studies assessing the role of HMGB1 in TB infection. In this prospective study, we aimed to assess the levels of HMGB1 in plasma or sputum from active pulmonary tuberculosis (APTB) patients positive for Mtb culture test, and to evaluate its relationship with inflammatory cytokines and innate immune cells. A total of 36 sputum Mtb culture positive APTB patients and 32 healthy volunteers (HV) were included. Differentiated THP-1 cells were treated for 6, 12 and 24 hrs with BCG at a multiplicity of infection of 10. The absolute values and percentages of white blood cells (WBC), neutrophils, lymphocytes, and monocytes were detected by an automatic blood analyzer. Levels of HMGB1, IL-6, IL-10 and TNF-α in plasma, sputum, or cell culture supernatant were measured by ELISA. The blood levels of HMGB1, IL-6, IL-10 and TNF-α, the absolute values of WBC, monocytes and neutrophils, and the percentage of monocytes were significant higher in APTB patients than those in HV groups (P<0.05). The sputum levels of HMGB1, IL-10, and TNF-α were also significantly higher in APTB patients than those in HV groups (P<0.05). Meanwhile, plasma level of HMGB1, IL-6, and IL-10 in APTB patients were positively correlated with those in sputum (P<0.05), respectively. IL-6 was positively correlated with HMGB1 both in plasma and sputum of APTB patients (P<0.05). HMGB1 and IL-6 is positively correlated with the absolute number of monocytes in APTB patients (P<0.05). BCG induced HMGB1, IL-6, IL-10 and TNF-α production effectively in PMA-treated THP-1 cells. HMGB1 may be used as an attractive biomarker for APTB diagnosis and prognosis and may reflect the inflammatory status of monocytes in patients with APTB.     

Recruitment of dendritic cells in human liver with metastases

Dendritic cells (DCs) play a key role in the generation of antitumor immune responses as the most potent professional antigen-presenting cells. In this study we examined the distribution of DCs subsets in selected areas of liver metastases and adjacent liver tissue of 74 patients with gastrointestinal cancers (14 gastric, 47 colon, and 13 rectal) using immunohistochemistrty for the DCs markers S-100 protein, HLA-DR, CD1a, and CD83. S-100 protein-positive DCs were localized mainly in clusters in metastases and at the tumor border with the surrounding liver tissue, while HLA-DR-positive DCs were significantly more in number (P < 0.0001) and were diffusely distributed in metastasis stroma and at the tumor border. S-100 protein-positive DCs with mature phenotype were presented around metastases and in the sinusoidal lumena, whereas S-100 protein-positive DCs with less mature phenotype based on their ultrastructure were scattered in the tumor stroma. CD1a- and CD83-positive DCs were observed predominantly in small groups or as single cells in the tumor stroma and in the invasive margin. The numbers of CD1a-positive DCs (immature) and CD83-positive DCs (mature) were comparable, but significantly lower than that of S-100 protein-positive (P < 0.0001) and HLA-DR-positive cells (P < 0.0001).We observed more S-100 protein-positive DCs and HLA-DR-expressing cells in the sinusoids and portal tracts of the liver tissue, surrounding metastases, than in control liver tissue. In conclusion, this study provides additional information on the functional subtypes and distribution of DCs infiltrating metastatic tissue and local liver environment in patients with liver metastases from gastrointestinal cancers.     

Levels of the soluble forms of CD80, CD86, and CD83 are elevated in the synovial fluid of rheumatoid arthritis patients

The release of soluble forms of CD80 (sCD80), CD86 (sCD86), and CD83 (sCD83) provide a potentially powerful immunoregulatory mechanism. We therefore investigated the potential presence and relative levels of these molecules in the synovial fluid (SF) and serum of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). Serum and SF levels were measured by enzyme-linked immunosorbent assay. Serum levels of sCD80, sCD86, and sCD83 in RA and OA patients were similar to those present in normal donor serum (NDS) and the SF of OA patients. In contrast, when compared with NDS and OA SF levels, almost all RA SF samples had elevated sCD83 levels (32/35, >0.63 ng/ml) and a substantial proportion had elevated sCD80 (13/29, >0.22 ng/ml) or sCD86 (16/33, >2.31 ng/ml) levels. Analysis of matched pairs of serum and SF from RA patients demonstrated that the SF/serum ratio for sCD80 (95% CI = 1.7-3), sCD86 (95% CI = 1.5-3.1), and sCD83 (95% CI = 3.6-7.8) levels was >1 in almost all patients. In conclusion, this study shows that the SF from almost all RA patients contain elevated levels of sCD83 and the majority of these samples also contain elevated levels of sCD80 and/or sCD86. These molecules may play a role in modulating immune responses within the rheumatoid joint.     

哮喘患者外周血DC参与Th2型偏移

体外诱导和扩增树突状细胞(DC)并从形态学、细胞超微结构、特异性表面标志、分泌的细胞因子和混合淋巴细胞反应等五方面予以鉴定并研究其在哮喘中的生物学功能。采用正常人外周血单个核细胞(PBMC)经贴壁去除悬浮细胞,加入细胞因子(IL-4、GM-CSF)培养7 d后,LPS刺激其成熟。通过形态学观察、特异性表面标志、分泌细胞因子IL-12的能力及混合淋巴细胞反应予以鉴定,ELISA法检测DC分泌的细胞因子IL-12以及与自身T细胞反应后,流式细胞术检测T细胞分泌的胞内细胞因子IL-4和IFN-γ水平。结果显示正常人外周血诱导的DC具有典型的树突状突起和超微结构,高表达特异性表面标志物CD1a和CD83,分泌细胞因子IL-12以及很强的促进T细胞增殖功能。DC诱导培养第8天,哮喘组DC分泌的IL-12水平低于正常对照组,差异有显著性意义(P<0.01);混合培养第7天,哮喘组IFN-γ水平低于正常对照组(P<0.05),而IL-4和IL-4/IFN-γ比值均高于正常对照组,有显著性差异(P<0.01)。因而PBMC经细胞因子的序贯培养,可获得高纯度、功能性的DC,且该DC能通过调节IL-12的分泌在哮喘发病机制中发挥重要作用,为DC在肿瘤免疫、感染免疫、抗移植排斥等方面的研究奠定了基础。     

Glucocorticoids hamper the ex vivo maturation of lung dendritic cells from their low autofluorescent precursors in the human bronchoalveolar lavage: decreases in allostimulatory capacity and expression of CD80 and CD86

Dendritic cells (DCs) were prepared from human bronchoalveolar lavage (BAL) cells. We previously reported that, in particular, the CD1a fraction of the low autofluorescent (LAF) cells contains the precursors for DCs: after overnight culture, 40% of the LAF cells change into functionally and phenotypically prototypic dendritic/veiled cells. There are, as yet, no data on the modulatory effects of glucocorticoids (GC) on the maturation and function of such DCs isolated from the human lung. Functional tests (allogeneic mixed lymphocyte reaction: allo-MLR) were therefore performed with CD1a+ LAF cells at different stimulator-to-T-cell ratios and after preincubation with different dexamethasone (DEX) concentrations. DEX caused suppression of the T-cell stimulatory capacity of CD1a+ LAF cells, which was dose-dependent, and more evident at the higher stimulator-to-T-cell ratios. Here, we also show that CD80 and CD86 are normally expressed at low levels on CD1a+ LAF cell-derived DCs compared to other DC populations. This low-level expression of costimulatory molecules is discussed here in relation to the previously reported low-level expression of CD80 (and CD86) on lung DCs in experimental animals. This appears to play a role in a predominant Th2 cell stimulating potential of DC from the lung environment. DEX exposure of CD1a+ LAF cells prevented the upregulation of even this low-level expression of CD80 and CD86. The veiled/dendritic morphology and the expression of other relevant cell surface markers and adhesion molecules was not affected by DEX exposure. It is concluded that DEX hampers the maturation of CD1a+ LAF cells into active lung DCs.     

Correlation of dendritic cell infiltration with active crypt inflammation in ulcerative colitis

The aim of this study was to evaluate the histological localization and phenotypic characteristics of infiltrating dendritic cells (DCs) and to examine the relationship between the degree of DC infiltration and the severity of inflammation in the colonic mucosa in ulcerative colitis (UC). Also explored was the expression of macrophage inflammatory protein-3alpha (MIP-3alpha), and its receptor CC-chemokine receptor 6 (CCR6), to evaluate the significance of immature DCs in the crypt inflammation evident in UC. There was a significant positive correlation between the number of infiltrating DCs and the degree of crypt inflammation, mononuclear cell infiltration, crypt atrophy, and comprehensive active inflammation. No significant correlation between the number of S-100 protein(+) cells and the severity of crypt atrophy was found. S-100 protein(+), MIP-3alpha(+), and CCR6(+) cells were frequently localized in or around the crypt with inflammation. MIP-3alpha(+) neutrophils and S-100 protein(+) CCR6(+) cells with dendritic morphology were detected in or around the crypt inflammation. Both S-100 protein(+) DCs and CCR6(+) cells were frequently clustered in the surface mucosa beneath the surface epithelium when the crypt was not inflamed. CD1a(+) Langerhans-cell-type DCs were not found in any of the tissues examined. These data indicate that DCs participate not only in chronic inflammation but also in active crypt inflammation.     

Type 1 diabetes patients have significantly lower frequency of plasmacytoid dendritic cells in the peripheral blood

Dendritic cells uniquely orchestrate the delicate balance between T cell immunity and regulation and an imbalance favoring immunogenic rather than tolerogenic DC is believed to contribute to the development of autoimmune diseases such as type 1 diabetes (T1D). In this study, we determined the frequencies of three blood DC subsets (pDC, mDC1 and mDC2) in 72 T1D patients and 75 normal controls using the Miltenyi blood DC enumeration kit. The frequency of blood pDC was found to be negatively correlated with subject age in both normal controls and T1D patients (p=0.0007), while the frequency of mDC1 and mDC2 do not change significantly with subject age. More importantly, the mean frequency of pDC in blood was, after adjusting for age, significantly lower in T1D (mean=0.127%) than controls (mean=0.188%) (p<6.0 x 10(-5)), whereas no difference was observed for mDC1 and mDC2 between T1D and controls. Furthermore, T1D patients have a lower proportion of pDC and higher proportion of mDC1 among the total blood DC population than normal controls. These results indicate that the frequency of blood pDC and the pDC/mDC1 ratio are negatively associated with T1D.     

Langerhans cells and more: langerin-expressing dendritic cell subsets in the skin

Summary: Langerhans cells (LCs) are antigen-presenting dendritic cells (DCs) that reside in epithelia. The best studied example is the LC of the epidermis. By electron microscopy, their identifying feature is the unique rod- or tennis racket-shaped Birbeck granule. The phenotypic hallmark is their expression of the C-type lectin receptor langerin/CD207. Langerin, however, is also expressed on a recently discovered population of DC in the dermis and other tissues of the body. These ‘dermal langerin⁺ dendritic cells’ are unrelated to LCs. The complex field of langerin-negative dermal DCs is not dealt with here. In this article, we briefly review the history, ontogeny, and homeostasis of LCs. More emphasis is laid on the discussion of functional properties in vivo. Novel models using genetically engineered mice are contributing tremendously to our understanding of the role of LCs in eliciting adaptive immune responses against pathogens or tumors and in inducing and maintaining tolerance against self antigens and innocuous substances in vivo. Also, innate effector functions are increasingly being recognized. Current activities in this area are reviewed, and possibilities for future exploitation of LC in medicine, e.g. for the improvement of vaccines, are contemplated.     

Distinctive role of efferocytosis in dendritic cell maturation and migration in sterile or infectious conditions

Efferocytosis, or clearance of apoptotic cells (ACs), by dendritic cells (DCs) leads to immune response suppression and tolerance to self‐antigens. However, efferocytosis of infected apoptotic cells (IACs) leads to the production of a mixed pro‐ and anti‐inflammatory cytokine milieu. We examined the DC phenotype and ability to migrate after phagocytosis of ACs or IACs and observed higher levels of CD86 and CCR7 expression in DCs, as well as enhanced migration capacity following efferocytosis of IACs. Interestingly, higher levels of interleukin‐1β, interleukin‐10 and prostaglandin E₂ (PGE₂) were also produced in this context. Blockage of IAC recognition led to an impaired maturation profile and PGE₂ production, which may have contributed to reduced CD86 and CCR7 expression and migration capacity. These data contribute to the understanding of how efferocytosis of sterile or infected cells may regulate the adaptive immune response, although the precise role of PGE₂ in this process requires further investigation.     

Increased expression of DC-SIGN+IL-12+IL-18+ and CD83+IL-12-IL-18- dendritic cell populations in the colonic mucosa of patients with Crohn's disease

Dentritic cells (DC) as antigen-presenting cells are most likely responsible for regulation of abnormal T cell activation in Crohn's disease (CD), a chronic inflammatory bowel disease. We have analyzed the expression of activation and maturation markers on DC in the colon mucosa from patients with CD compared with normal colon, using immunohistochemical techniques. We found two distinct populations of DC present in CD patients: a DC-specific ICAM-3 grabbing non-integrin (DC-SIGN)(+) population that was present scattered throughout the mucosa, and a CD83(+) population that was present in aggregated lymphoid nodules and as single cells in the lamina propria. In normal colon the number of DC-SIGN(+) DC was lower and CD83(+) DC were detected only in very few solitary lymphoid nodules. Co-expression of activation markers and cytokine synthesis was analyzed with three-color confocal laser scanning microscopy analysis. CD80 expression was enhanced on the majority of DC-SIGN(+) DC in CD patients, whereas only a proportion of the CD83(+) DC co-expressed CD80 in CD as well as in normal tissue. Surprisingly, IL-12 and IL-18 were only detected in DC-SIGN(+) DC and not in CD83(+) DC. A similar pattern of cytokine production was observed in normal colon albeit to a much lesser extent. The characteristics of these in-situ-differentiated DC markedly differ from the in-vitro-generated DC that simultaneously express DC-SIGN, CD83 and cytokines.