Inflammatory Dendritic Cells Research Articles

IL-4-Producing Dendritic Cells Induced during Schistosoma japonica Infection Promote Th2 Cells via IL-4-Dependent Pathway.

Although dendritic cells (DCs) have been widely demonstrated to play essential roles in initiation of Th2 responses in helminth infections and allergic reactions, the mechanisms remain uncertain largely because DCs do not produce IL-4. In present investigation, we have uncovered a novel subset of DCs from mice infected with Th2-provoking pathogens Schistosoma japonica, which independently promoted Th2 cells via IL-4-dependent pathway. These DCs contained similar levels of IL-4 mRNA and higher levels of IL-12p40 mRNA comparing to basophils, correlating to their Th2-promoting and Th1-promoting dual polarization capacities. Characterized by expression of FcεRI(+), these DCs were induced independent of T cells. Further investigations revealed that Th2-promoting FcεRI(+) DCs were monocyte-derived inflammatory DCs, which were sufficient to induce Th2 cells in vivo. Egg Ags together with GM-CSF or IL-3 alone were able to stimulate the generation of Th2-promoting FcεRI(+) DCs from bone marrow cells in vitro. To our knowledge, our data for the first time demonstrate that IL-4-producing DCs are induced under some Th2-provoking situations, and they should play important roles in initiation of Th2 response.

In vivo confocal microscopy of early corneal epithelial recovery in patients with chemical injury.

To investigate the early recovery of corneal epithelium in patients with chemical injuries by the application of in vivo laser scanning confocal microscopy (LSCM). LSCM was performed on 26 eyes of 18 consecutive patients at 1, 2, and 3 months post injury. The morphology of central corneal epithelium and limbus was evaluated. Analysis was performed to compare the densities of corneal apical surface cells (ASCs) and basal epithelial cells (BECs) among different injury severity and time points after injury. The comparisons were also made on inflammatory cells (ICs) and dendritic cells (DCs) infiltrating at the limbus. Moreover, the presence rate of palisades of Vogt (POV) was analyzed at 3 months post injury. Corneal re-epithelialization was found within 3 months post injury in all eyes, except that persistent epithelium defect was identified in grade IV injured eyes even at 3 months after injury. The injury severity had a significantly negative correlation with the densities of ASCs. However, it had no relationship with the densities of BECs. The density of ICs at the limbus decreased significantly with the prolongation of follow-up, except in the grade I injured eyes. The presence rate of POV also had a significantly negative correlation with injury severity. Epithelial recovery after chemical injury varied in cellular morphology and the densities of ASCs among eyes with different injury severity. The presence rates of POV decreased with the aggravation of injury. LSCM is a feasible method for observing the early recovery of corneal epithelium in patients with chemical injuries.

CX3CR1-expressing inflammatory dendritic cells contribute to the progression of steatohepatitis.

Liver monocytes play a major role in the development of NASH (non-alcoholic steatohepatitis). In inflamed tissues, monocytes can differentiate in both macrophages and dendritic cells. In the present study, we investigated the role of moDCs (monocyte-derived inflammatory dendritic cells) in experimental steatohepatitis induced in C57BL/6 mice by feeding on a MCD (methionine/choline-deficient) diet. The evolution of steatohepatitis was characterized by an increase in hepatic CD45+ / CD11b+ myeloid cells displaying the monocyte/macrophage marker F4-80(+). In the early phases (4 weeks of treatment), Ly6C(high)/CD11b(+)/F4-80(+) inflammatory macrophages predominated. However, their frequency did not grow further with the disease progression (8 weeks of treatment), when a 4-fold expansion of CD11b(+)/F4-80(+) cells featuring the fractalkine receptor (CX3CR1) was evident. These CX3CR1+ cells were also characterized by the combined expression of inflammatory monocyte (Ly6C, CD11b) and dendritic cell (CD11c, MHCII) markers as well as by a sustained TNFα (tumour necrosis factor α) production, suggesting monocyte differentiation into inflammatory moDCs. The expansion of TNFα-producing CX3CR1+ moDCs was associated with an elevation in hepatic and circulating TNFα level and with the worsening of parenchymal injury. Hydrogen sulfide (H2S) has been shown to interfere with CX3CR1 up-regulation in monocyte-derived cells exposed to pro-inflammatory stimuli. Treating 4-week-MCD-fed mice with the H2S donor NaHS while continuing on the same diet prevented the accumulation of TNFα-producing CX3CR1+ moDCs without interfering with hepatic macrophage functions. Furthermore, NaHS reduced hepatic and circulating TNFα levels and ameliorated transaminase release and parenchymal injury. Altogether, these results show that inflammatory CX3CR1+ moDCs contributed in sustaining inflammation and liver injury during steatohepatitis progression.

Application of confocal laser scanning microscopy in the diagnosis of hypopigmentation disorders in children

Objective To investigate the microscopic features of common hypopigmentation disorders using confocal laser scanning microscopy (CLSM). Methods Totally, 1915 child patients with hypopigmentation disorders were enrolled in this study, including 181 cases of vitiligo, 38 idiopathic guttate hypomelanosis, 370 amelanotic nevus, 304 lichen striatus, 712 pityriasis alba, and 310 postinflammatory hypopigmentation. CLSM was performed to observe all layers of depigmented lesions, their borders, and normal-appearing perilesional skin in these patients. Statistical analysis was done by chi-square test and Fisher's exact test. Results Grade 1 and 2 hypopigmentation was observed in 984 (51.4% ) and 684 (35.7% ) out of the 1915 patients, respectively. The proportion of patients with grade 3 hypopigmentation was 77.9% (141/181) in patients with vitiligo, significantly higher than that in those with the other diseases (0 - 10.3% ). Among the 1915 patients, 815 showed mild epidermal hyperkeratosis, 1060 focal edema of stratum spinosum, 79 changes in dermal papillary rings, and 1133 sparse inflammatory cells or dendritic cells in the superficial dermis. There were significant differences in the degree of hypopigmentation and frequencies of pathologic changes in different skin layers on CLSM images among the six hypopigmentation disorders (all P < 0.05). As CLSM showed, idiopathic guttate hypomelanosis was characterized by complete absence of dermal papillary rings; lichen striatus, pityriasis alba and postinflammatory hypopigmentation were all characterized by nonspecific inflammatory changes; lichen striatus manifested as punctiform or focal liquifaction degeneration of basal cells, and amelanotic nevus as only hypopigmentation and refractive attenuation; vitiligo was characterized by complete depigmentation and lack of integrity of dermal papillary rings in white patches. Conclusions CLSM images obviously differ between vitiligo, idiopathic guttate hypomelanosis, amelanotic nevus, lichen striatus, pityriasis alba and postinflammatory hypopigmentation, and can serve as a basis for their differential diagnosis. Key words: Microscopy, confocal; Hypopigmentation; Vitiligo; Child; Melanins; Dermal papillary rings; Pityriasis alba; Lichen striatus; Amelanotic nevus

Hyaluronan Binding Identifies a Functionally Distinct Alveolar Macrophage-like Population in Bone Marrow-Derived Dendritic Cell Cultures.

Although classical dendritic cells (DCs) arise from distinct progenitors in the bone marrow, the origin of inflammatory DCs and the distinction between monocyte-derived DCs and macrophages is less clear. In vitro culture of mouse bone marrow cells with GM-CSF is a well-established method to generate DCs, but GM-CSF has also been used to generate bone marrow-derived macrophages. In this article, we identify a distinct subpopulation of cells within the GM-CSF bone marrow-derived DC culture based on their ability to bind hyaluronan (HA), a major component of the extracellular matrix and ligand for CD44. HA identified a morphologically distinct subpopulation of cells within the immature DC population (CD11c(+) MHC II(mid/low)) that were CCR5(+)/CCR7(-) and proliferated in response to GM-CSF, but, unlike immature DCs, did not develop into mature DCs expressing CCR7 and high levels of MHC II, even after stimulation with LPS. The majority of these cells produced TNF-α in response to LPS but were unable to activate naive T cells, whereas the majority of mature DCs produced IL-12 and activated naive T cells. This HA binding population shared many characteristics with alveolar macrophages and was retained in the alveolar space after lung instillation even after LPS stimulation, whereas the MHC II(high) mature DCs were found in the draining lymph node. Thus, HA binding in combination with MHC II expression can be used to identify alveolar-like macrophages from GM-CSF-treated bone marrow cultures, which provides a useful in vitro model to study alveolar macrophages.

CD81 controls immunity to Listeria infection through rac-dependent inhibition of proinflammatory mediator release and activation of cytotoxic T cells.

Despite recent evidence on the involvement of CD81 in pathogen binding and Ag presentation by dendritic cells (DCs), the molecular mechanism of how CD81 regulates immunity during infection remains to be elucidated. To investigate the role of CD81 in the regulation of defense mechanisms against microbial infections, we have used the Listeria monocytogenes infection model to explore the impact of CD81 deficiency in the innate and adaptive immune response against this pathogenic bacteria. We show that CD81(-/-) mice are less susceptible than wild-type mice to systemic Listeria infection, which correlates with increased numbers of inflammatory monocytes and DCs in CD81(-/-) spleens, the main subsets controlling early bacterial burden. Additionally, our data reveal that CD81 inhibits Rac/STAT-1 activation, leading to a negative regulation of the production of TNF-α and NO by inflammatory DCs and the activation of cytotoxic T cells by splenic CD8α(+) DCs. In conclusion, this study demonstrates that CD81-Rac interaction exerts an important regulatory role on the innate and adaptive immunity against bacterial infection and suggests a role for CD81 in the development of novel therapeutic targets during infectious diseases.

De novo-induced self-antigen-specific Foxp3+ regulatory T cells impair the accumulation of inflammatory dendritic cells in draining lymph nodes.

Foxp3(+) regulatory T cell (Treg)-based immunotherapy holds promise for autoimmune diseases. However, this effort has been hampered by major caveats, including the low frequency of autoantigen-specific Foxp3(+) Tregs and lack of understanding of their molecular and cellular targets, in an unmanipulated wild-type (WT) immune repertoire. In this study, we demonstrate that infusion of myelin in WT mice results in the de novo induction of myelin-specific Foxp3(+) Tregs in WT mice and amelioration of experimental autoimmune encephalomyelitis. Myelin-specific Foxp3(+) Tregs exerted their effect both by diminishing Ag-bearing inflammatory dendritic cell (iDC) recruitment to lymph nodes and by impairing their function. Transcriptome analysis of ex vivo-isolated Treg-exposed iDCs showed significant enrichment of transcripts involved in functional properties of iDCs, including chemotaxis-related genes. To this end, CCR7 expression by iDCs was significantly downregulated in tolerant mice and this was tightly regulated by the presence of IL-10. Collectively, our data demonstrate a novel model for deciphering the Ag-specific Foxp3(+) Treg-mediated mechanisms of tolerance and delineate iDCs as a Foxp3(+) Treg cellular target in unmanipulated mice.

Involvement of CD300a Phosphatidylserine Immunoreceptor in Aluminum Salt Adjuvant-Induced Th2 Responses.

Aluminum salt (alum) has been widely used for vaccinations as an adjuvant. Alum not only enhances immunogenicity but also induces Th2 cell immune responses. However, the mechanisms of how alum enhances Th2 cell immune responses have been controversial. In an experimental allergic airway inflammation model, in which alum in conjunction with OVA Ag was i.p. injected for immunization, we found that apoptotic cells and inflammatory dendritic cells (iDC) expressing CD300a, an inhibitory immunoreceptor for phosphatidylserine (PS), significantly increased in number in the peritoneal cavity after the immunization. In contrast, apoptotic cells and iDCs were scarcely observed in the peritoneal cavity after injection of OVA alone. In CD300a-deficient mice, eosinophil infiltration in bronchoalveolar lavage fluid, serum IgE levels, and airway hyperreactivity were significantly decreased after immunization with alum plus OVA compared with wild-type mice. In vitro, iDCs purified from CD300a-deficient mice after the immunization induced significantly less IL-4 production from OT-II naive CD4(+) T cells after coculture with OVA Ag. CD300a expressed on iDCs bound PS on apoptotic cells in the peritoneal cavity after injection of OVA plus alum. Blocking CD300a interaction with PS by injection of a neutralizing anti-CD300a Ab resulted in inhibition of the development of allergic airway inflammation. These results suggest that CD300a is involved in alum-induced Th2 skewing.

Microglia Versus Myeloid Cell Nomenclature during Brain Inflammation.

As immune sentinels of the central nervous system (CNS), microglia not only respond rapidly to pathological conditions but also contribute to homeostasis in the healthy brain. In contrast to other populations of the myeloid lineage, adult microglia derive from primitive myeloid precursors that arise in the yolk sac early during embryonic development, after which they self-maintain locally and independently of blood-borne myeloid precursors. Under neuro-inflammatory conditions such as experimental autoimmune encephalomyelitis, circulating monocytes invade the CNS parenchyma where they further differentiate into macrophages or inflammatory dendritic cells. Often it is difficult to delineate resident microglia from infiltrating myeloid cells using currently known markers. Here, we will discuss the current means to reliably distinguish between these populations, and which recent advances have helped to make clear definitions between phenotypically similar, yet functionally diverse myeloid cell types.

Amelioration of allergic airway inflammation in mice by regulatory IL-35 through dampening inflammatory dendritic cells.

IL-35, a new member of the IL-12 family, is an inhibitory cytokine produced by regulatory T and B lymphocytes that play a suppressive role in the inflammatory diseases. This study focuses on the cellular mechanism regulating the anti-inflammatory activity of IL-35 in asthmatic mice. Ovalbumin-induced asthmatic and humanized asthmatic mice were adopted to evaluate the invivo anti-inflammatory activities of IL-35. For monitoring the airway, Penh value (% baseline) was measured using a whole-body plethysmograph. In this study using ovalbumin-induced asthmatic mice, we observed that intraperitoneal injection of IL-35 during the allergen sensitization stage was more efficient than administration in the challenge stage for the amelioration of airway hyper-responsiveness. This was reflected by the significantly reduced concentration of asthma-related Th2 cytokines IL-5 and IL-13, as well as eosinophil counts in bronchoalveolar lavage fluid (all P<0.05). IL-35 also significantly attenuated the accumulation of migratory CD11b+CD103(-) dendritic cells (DC) in the mediastinal lymph node (mLN) and lung of mice (all P<0.05). IL-35 markedly inhibited the ovalbumin-induced conversion of recruited monocytes into inflammatory DC, which were then substantially reduced in mLN to cause less T-cell proliferation (all P<0.05). Further study using the humanized asthmatic murine model also indicated human IL-35 exhibited a regulatory impact on allergic asthma. Our findings suggest that IL-35 can act as a crucial regulatory cytokine to inhibit the development of allergic airway inflammation via suppressing the formation of inflammatory DC at the inflammatory site and their accumulation in the draining lymph nodes.

Development of uptake capacity and bactericidal activity in myeloid cells during GM-CSF-driven differentiation. (INC6P.326)

Abstract The antigen presenting function of dendritic cells (DC) is well defined, yet their ability to handle bacterial infection is poorly understood. We have previously shown that GM-CSF-derived DC can confine Listeria monocytogenes (Lm) to the phagosome, preventing its invasion of the cytosol, growth, and spread. However, it is not clear at what stage of development DC acquire the capacity to retain Lm in the phagosome. To measure this activity at different stages of development, GM-CSF driven bone marrow cells were sorted based on expression of Ly6C, CD115, and CD11c. This strategy enables isolation of cells representing five distinct myeloid cell types: CMP, GMP, monocytes, inflammatory dendritic precursors (IDP), and inflammatory DC (IDC). To measure bacterial invasion of the cytosol, we used an Lm strain that expresses GFP upon cytoplasmic entry, in combination with fluorescent bioparticles to measure bulk uptake. The CMP demonstrated minimal uptake capacity and little bacterial cytoplasmic entry. The GMP population showed greatly increased uptake capacity, but also high susceptibility to bacterial cytoplasmic entry. In the monocyte population, the uptake capacity reached its peak, and these cells gained the capacity to confine the bacteria to the phagosome. Finally, the uptake capacity decreased modestly in the IDP and IDC populations, but these cells also blocked cytoplasmic invasion of the bacteria. The mechanistic basis of phagosomal retention was further examined.

Protection of human myeloid dendritic cell subsets against influenza A virus infection is differentially regulated upon TLR stimulation.

The proinflammatory microenvironment in the respiratory airway induces maturation of both resident and infiltrating dendritic cells (DCs) upon influenza A virus (IAV) infection. This results in upregulation of antiviral pathways as well as modulation of endocytic processes, which affect the susceptibility of DCs to IAV infection. Therefore, it is highly relevant to understand how IAV interacts with and infects mature DCs. To investigate how different subsets of human myeloid DCs (MDCs) involved in tissue inflammation are affected by inflammatory stimulation during IAV infection, we stimulated primary blood MDCs and inflammatory monocyte-derived DCs (MDDCs) with TLR ligands, resulting in maturation. Interestingly, MDDCs but not MDCs were protected against IAV infection after LPS (TLR4) stimulation. In contrast, stimulation with TLR7/8 ligand protected MDCs but not MDDCs from IAV infection. The reduced susceptibility to IAV infection correlated with induction of type I IFNs. We found that differential expression of TLR4, TRIF, and MyD88 in the two MDC subsets regulated the ability of the cells to enter an antiviral state upon maturation. This difference was functionally confirmed using small interfering RNA and inhibitors. Our data show that different human MDC subsets may play distinct roles during IAV infection, as their capacity to induce type I IFNs is dependent on TLR-specific maturation, resulting in differential susceptibility to IAV infection.

Lymphotoxin β receptor signaling promotes influenza-induced lung damage (VIR5P.1151)

Abstract Lymphotoxin β receptor (LTβR) has been shown to play a critical role in protection against mucosal bacterial pathogens in the gut. Surprisingly, we found that genetic or biochemical inhibition of LTβR signaling confers protection against highly pathogenic H1N1 influenza virus infection. Consistent with amelioration of disease severity, LTβR-deficient mice displayed reduced expression of pro-inflammatory cytokines, reduced inflammatory dendritic cells, and drastically reduced numbers of antigen specific CD8+ T cells in the lung. Further, LTβR-deficient mice showed attenuated viral loads during the peak of viral replication. Previous studies by our group have highlighted a potential role of LT signaling in the regulation of mucin expression in the gut. Further, increased mucin secretion in the lung is known to correlate with attenuation of influenza virus replication. Immunohistochemical and gene expression analysis revealed a marked increase in goblet cell hyperplasia and MUC5AC secretion in the lungs of influenza infected LTβR-deficient mice relative to wild type mice. Additionally, treatment of infected wild type mice with an agonistic anti-LTβR antibody resulted in almost complete inhibition of MUC5AC mRNA expression in the lung. Taken together, our data suggest that LT signaling negatively regulates mucin production in response to respiratory viral infection leading to increased viral burden, lung pathology, and death.

Synovial CD4+ T-cell-derived GM-CSF supports the differentiation of an inflammatory dendritic cell population in rheumatoid arthritis

ObjectiveA population of synovial inflammatory dendritic cells (infDCs) has recently been identified in rheumatoid arthritis (RA) and is thought to be monocyte-derived. Here, we investigated the role and source of...

The diverging roles of dendritic cells in kidney allotransplantation

Dendritic cells (DCs) are a family of antigen presenting cells that play a paramount role in bridging innate and adaptive immunity. In murine models several subtypes of DCs have been identified, including classical DCs, monocyte-derived DCs, and plasmacytoid DCs. Quiescent, immature DCs and some subtypes of plasmacytoid cells favor the expression of regulatory T cells, but in an inflammatory milieu DCs become mature and after intercepting the antigen migrate to lymphatic system where they present the antigen to naïve T cells. Transplant rejection largely depends on the phenotype and maturation of DCs. The ischemia-reperfusion injury causes the release of endogenous molecules that are recognized as danger signals by the pattern recognition receptor of the innate immunity with subsequent activation of inflammatory cells and mediators. In this environment DCs become mature and migrate to lymphonodes where they present the alloantigen to T cells and direct their differentiation towards Th1 and Th17 effector cells. On the other hand, manipulation of DCs may favor T cell differentiation towards tolerant Th2 and T regulators (Treg). Experimental studies in murine models showed the possibility of inducing an operational tolerance by injecting immature tolerogenic DCs. Recently, such a possibility has been also confirmed in primates. Although manipulation of DCs may represent an important step ahead in kidney transplantation, a number of technical and ethical issues should be solved before its clinical application.

Anti-CD40-induced inflammatory E-cadherin+ dendritic cells enhance T cell responses and antitumour immunity in murine Lewis lung carcinoma

BackgroundAgonistic CD40 antibodies have been demonstrated to activate antigen-presenting cells (APCs) and enhance antitumour T cell responses, thereby providing a new therapeutic option in cancer immunotherapy. In agonistic CD40 antibody-mediated inflammatory responses, a novel subset of E-cadherin + dendritic cells (DCs) has been identified, and little is known about the role of these DCs in tumour immunity. This study investigated the effect of anti-CD40-mediated inflammatory E-cadherin + DCs in murine Lewis lung carcinoma (LLC).MethodsThe phenotype and characteristics of anti-CD40-mediated inflammatory E-cadherin + DCs isolated from the anti-CD40 model were assessed in vitro. The antitumour activity of E-cadherin + DCs were evaluated in vivo by promoting the differentiation of effector CD4+ T cells, CEA-specific CD8+ T cells and CD103+ CD8+ T cells and assessing their resistance to tumour challenge, including variations in tumour volume and survival curves.ResultsHere, we demonstrated that anti-CD40-mediated E-cadherin + inflammatory DCs accumulate in the lungs of Rag1 KO mice and were able to stimulate naïve CD4+ T cells to induce Th1 and Th17 cell differentiation and polarisation and to inhibit regulatory T cell and Th2 responses. Importantly, with the adoptive transfer of E-cadherin + DCs into the Lewis lung cancer model, the inflammatory DCs increased the Th1 and Th17 cell responses and reduced the Treg cell and Th2 responses. Interestingly, following the injection of inflammatory E-cadherin + DCs, the CD103+ CD8+ T cell and CEA-specific CD8+ T cell responses increased and exhibited potent antitumour immunity.ConclusionsThese findings indicate that anti-CD40-induced E-cadherin + DCs enhance T cell responses and antitumour activity in non-small cell lung cancer (NSCLC)-bearing mice and may be used to enhance the efficacy of DC-based peptide vaccines against NSCLC.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-015-0126-9) contains supplementary material, which is available to authorized users.

Increased Numbers of 6-sulfo LacNAc (slan) Dendritic Cells in Hand Transplant Recipients

Vascularized composite allotransplantation (VCA) is a modern option for the treatment of functionally significant limb and tissue defects. In our study we aimed to characterize the morphological and histological features of the hand transplant recipient skin rejection. We clinically evaluated the skin and mucous membranes and microscopically assessed biopsies taken from the patient's own skin and from the allogenic grafted limb (n=5). We also performed immunohistochemistry for presence of T lymphocytes (CD3, CD4, and CD8), B lymphocytes (CD20), macrophages (CD68), Langerhans cells (CD1a+), plasmacytoid dendritic cells (pDCs) (CD123+) and 6-sulfo LacNAc+ dendritic cells (slanDCs) (DD2+). Only scattered pDCs were present in both own and skin grafts. The number of LC in the epidermis was higher in graft skin in all cases and CD1a+ cells were also present in the dermis in transplanted skin in patients with grade 1 rejection. Most interestingly, we identified far increased numbers of dermal slanDCs in the grafted skin. SlanDCs have a high capacity to produce proinflammatory cytokines and have been described as inflammatory dermal dendritic cells in psoriasis and lupus erythematosus. It may be hypothesized that slanDCs identified in the skin after limb transplantation may support the local inflammatory skin reaction.

Fluorescent activated cell sorting: An effective approach to study dendritic cell subsets in human atherosclerotic plaques

Different immune cell types are present within atherosclerotic plaques. Dendritic cells (DC) are of special interest, since they are considered as the ‘center of the immuniverse’. Identifying inflammatory DC subtypes within plaques is important for a better understanding of the lesion pathogenesis and pinpoints their contribution to the atherosclerotic process. We have developed a flow cytometry-based method to characterize and isolate different DC subsets (i.e. CD11b+, Clec9A+ and CD16+ conventional (c)DC and CD123+ plasmacytoid (p)DC) in human atherosclerotic plaques. We revealed a predominance of pro-inflammatory CD11b+ DC in advanced human lesions, whereas atheroprotective Clec9A+ DC were almost absent. CD123+ pDC and CD16+ DC were also detectable in plaques. Remarkably, plaques from distinct anatomical locations exhibited different cellular compositions: femoral plaques contained less CD11b+ and Clec9A+ DC than carotid plaques. Twice as many monocytes/macrophages were observed compared to DC. Moreover, relative amounts of T cells/B cells/NK cells were 6 times as high as DC numbers.For the first time, fluorescent activated cell sorting analysis of DC subsets in human plaques indicated a predominance of CD11b+ cDC, in comparison with other DC subsets. Isolation of the different subsets will facilitate detailed functional analysis and may have significant implications for tailoring appropriate therapy.

Control of pathogenic effector T-cell activities in situ by PD-L1 expression on respiratory inflammatory dendritic cells during respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) infection is a leading cause of severe lower respiratory tract illness in young infants, the elderly and immunocompromised individuals. We demonstrate here that the co-inhibitory molecule programmed cell death 1 (PD-1) is selectively upregulated on T cells within the respiratory tract during both murine and human RSV infection. Importantly, the interaction of PD-1 with its ligand PD-L1 is vital to restrict the pro-inflammatory activities of lung effector T cells in situ, thereby inhibiting the development of excessive pulmonary inflammation and injury during RSV infection. We further identify that PD-L1 expression on lung inflammatory dendritic cells is critical to suppress inflammatory T-cell activities, and an interferon-STAT1-IRF1 axis is responsible for increased PD-L1 expression on lung inflammatory dendritic cells. Our findings suggest a potentially critical role of PD-L1 and PD-1 interactions in the lung for controlling host inflammatory responses and disease progression in clinical RSV infection.

Automated image analysis in the study of lymphocyte subpopulation in eosinophilic oesophagitis.

BackgroundEosinophilic oesophagitis (EoE) is characterized by the presence of eosinophils in oesophageal mucosa. Other inflammatory cells, mainly lymphocytes, dendritic cells, and mast cells may also play an important role in this disease. The aim of this study is to compare the inflammatory pattern of the mucosa between EoE and gastro-oesophageal reflux disease (GERD), using automatic image analysis in digital slides, and to assess treatment response after elimination diet and food challenge test.MethodsFrom 2010 to 2013, 35 oesophageal biopsies from EoE and GERD patients were randomly selected. In six EoE biopsies, patients had been treated with selective food exclusion diet. Immunohistochemical study with CD3, CD20, CD4, and CD8 for lymphocyte populations, CD1a for dendritic cells, and CD117/c-kit for mast cells was performed. Slides were scanned using Leica Aperio Scanscope XT with 40× magnification. Immunohistochemical expression was quantified in 245 immunohistochemistry digital slides with Leica Aperio positive pixel count algorithm using two different approaches: whole slide analysis versus selection of a 2 mm2 hot spot area.ResultsAverage eosinophil cell count was significantly higher (p < 0.001) in the first biopsy of EoE patients before treatment (30.75 eosinophils per high power field - HPF) than in GERD patients (0.85 eosinophils/HPF) or in EoE patients after treatment with elimination diet (1.60 eosinophils/HPF). In the immunohistochemical study, manual count and automatic image analysis showed a significant increase in the number of CD3 and CD8 cells in EoE patients, compared with GERD patients. However, the increase of CD117/c-kit was only statistically significant when manual counting procedures were used. CD20 positive cell count also showed a non-statistically significant tendency to reduce after elimination diet treatment.Manual eosinophil count correlated much better with CD3 and CD8 count using hot spot approach than with a whole slide approach.ConclusionsPositive pixel count algorithm can be a useful tool to quantify the immunohistochemical expression of inflammatory cells in the diagnosis and follow up of eosinophilic oesophagitis.