Role of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Inflammation and Pathogen-Associated Interactions.

BACKGROUND: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is known as a major receptor for oxidized low-density lipoproteins (oxLDL) and plays a significant role in the genesis of atherosclerosis. Recent research has shown its involvement in cancer, ischemic stroke, and diabetes. LOX-1 is a C-type lectin receptor and is involved in the activation of immune cells and inflammatory processes. It may further interact with pathogens, suggesting a role in infections or the host's response. SUMMARY: This review compiles the current knowledge of potential implications of LOX-1 in inflammatory processes and in host-pathogen interactions with a particular emphasis on its regulatory role in immune responses. Also discussed are genomic and structural variations found in LOX-1 homologs across different species as well as potential involvements of LOX-1 in inflammatory processes from the angle of different cell types and organ-specific interactions. KEY MESSAGES: The results presented reveal both similar and different structures in human and murine LOX-1 and provide clues as to the possible origins of different modes of interaction. These descriptions raise concerns about the suitability, particularly of mouse models, that are often used in the analysis of its functionality in humans. Further research should also aim to better understand the mostly unknown binding and interaction mechanisms between LOX-1 and different pathogens. This pursuit will not only enhance our understanding of LOX-1 involvement in inflammatory processes but also identify potential targets for immunomodulatory approaches.

Antibody ligation of CEACAM1, CEACAM3, and CEACAM6, differentially enhance the cytokine release of human neutrophils in responses to Candida albicans.

Invasive candidiasis is a healthcare-associated fungal infection with a high mortality rate. Neutrophils, the first line of defense during fungal infections, express the immunoregulatory Candida albicans receptors CEACAM1, CEACAM3, and CEACAM6. We analyzed the effects of specific antibodies on C. albicans-induced neutrophil responses. CEACAM6 ligation by 1H7-4B and to some extent CEACAM1 ligation by B3-17, but not CEACAM3 ligation by 308/3-3, resulted in the immediate release of stored CXCL8 and altered transcriptional responses of the C. albicans-stimulated neutrophils. Integrated network analyses and dynamic simulations of signaling cascades predicted alterations in apoptosis and cytokine secretion. We verified that CEACAM6 ligation enhanced Candida-induced neutrophil apoptosis and increased long-term IL-1ß/IL-6 release in responses to C. albicans. CEACAM3 ligation, but not CEACAM1 ligation, increased the long-term release of pro-inflammatory IL-1ß/IL-6. Taken together, we demonstrated for the first time that ligation of CEACAM receptors differentially affects the regulation of C. albicans-induced immune functions in human neutrophils.

Inhibition of the NLRP3/IL-1ß axis protects against sepsis-induced cardiomyopathy.

BACKGROUND: Septic cardiomyopathy worsens the prognosis of critically ill patients. Clinical data suggest that interleukin-1ß (IL-1ß), activated by the NLRP3 inflammasome, compromises cardiac function. Whether or not deleting Nlrp3 would prevent cardiac atrophy and improve diastolic cardiac function in sepsis was unclear. Here, we investigated the role of NLRP3/IL-1ß in sepsis-induced cardiomyopathy and cardiac atrophy. METHODS: Male Nlrp3 knockout (KO) and wild-type (WT) mice were exposed to polymicrobial sepsis by caecal ligation and puncture (CLP) surgery (KO, n = 27; WT, n = 33) to induce septic cardiomyopathy. Sham-treated mice served as controls (KO, n = 11; WT, n = 16). Heart weights and morphology, echocardiography and analyses of gene and protein expression were used to evaluate septic cardiomyopathy and cardiac atrophy. IL-1ß effects on primary and immortalized cardiomyocytes were investigated by morphological and molecular analyses. IonOptix and real-time deformability cytometry (RT-DC) analysis were used to investigate functional and mechanical effects of IL-1ß on cardiomyocytes. RESULTS: Heart morphology and echocardiography revealed preserved systolic (stroke volume: WT sham vs. WT CLP: 33.1 ± 7.2 µL vs. 24.6 ± 8.7 µL, P < 0.05; KO sham vs. KO CLP: 28.3 ± 8.1 µL vs. 29.9 ± 9.9 µL, n.s.; P < 0.05 vs. WT CLP) and diastolic (peak E wave velocity: WT sham vs. WT CLP: 750 ± 132 vs. 522 ± 200 mm/s, P < 0.001; KO sham vs. KO CLP: 709 ± 152 vs. 639 ± 165 mm/s, n.s.; P < 0.05 vs. WT CLP) cardiac function and attenuated cardiac (heart weight-tibia length ratio: WT CLP vs. WT sham: -26.6%, P < 0.05; KO CLP vs. KO sham: -3.3%, n.s.; P < 0.05 vs. WT CLP) and cardiomyocyte atrophy in KO mice during sepsis. IonOptix measurements showed that IL-1ß decreased contractility (cell shortening: IL-1ß: -15.4 ± 2.3%, P < 0.001 vs. vehicle, IL-1RA: -6.1 ± 3.3%, P < 0.05 vs. IL-1ß) and relaxation of adult rat ventricular cardiomyocytes (time-to-50% relengthening: IL-1ß: 2071 ± 225 ms, P < 0.001 vs. vehicle, IL-1RA: 564 ± 247 ms, P < 0.001 vs. IL-1ß), which was attenuated by an IL-1 receptor antagonist (IL-1RA). RT-DC analysis indicated that IL-1ß reduced cardiomyocyte size (P < 0.001) and deformation (P < 0.05). RNA sequencing showed that genes involved in NF-κB signalling, autophagy and lysosomal protein degradation were enriched in hearts of septic WT but not in septic KO mice. Western blotting and qPCR disclosed that IL-1ß activated NF-κB and its target genes, caused atrophy and decreased myosin protein in myocytes, which was accompanied by an increased autophagy gene expression. These effects were attenuated by IL-1RA. CONCLUSIONS: IL-1ß causes atrophy, impairs contractility and relaxation and decreases deformation of cardiomyocytes. Because NLRP3/IL-1ß pathway inhibition attenuates cardiac atrophy and cardiomyopathy in sepsis, it could be useful to prevent septic cardiomyopathy.

Context-dependent regulation of immunoglobulin mutagenesis by p53.

p53 plays a major role in genome maintenance. In addition to multiple p53 functions in the control of DNA repair, a regulation of DNA damage bypass via translesion synthesis has been implied in vitro. Somatic hypermutation of immunoglobulin genes for affinity maturation of antibody responses is based on aberrant translesion polymerase action and must be subject to stringent control to prevent genetic alterations and lymphomagenesis. When studying the role of p53 in somatic hypermutation in vivo, we found altered translesion polymerase-mediated A:T mutagenesis in mice lacking p53 in all organs, but notably not in mice with B cell-specific p53 inactivation, implying that p53 functions in non-B cells may alter mutagenesis in B cells. During class switch recombination, when p53 prevents formation of chromosomal translocations, we in addition detected a B cell-intrinsic role for p53 in altering G:C and A:T mutagenesis. Thus, p53 regulates translesion polymerase activity and shows differential activity during somatic hypermutation versus class switch recombination in vivo. Finally, p53 inhibition leads to increased somatic hypermutation in human B lymphoma cells. We conclude that loss of p53 function may promote genetic instability via multiple routes during antibody diversification in vivo.

Unaltered Fungal Burden and Lethality in Human CEACAM1-Transgenic Mice During Candida albicans Dissemination and Systemic Infection.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1, CD66a) is a receptor for Candida albicans. It is crucial for the immune response of intestinal epithelial cells to this opportunistic pathogen. Moreover, CEACAM1 is of importance for the mucosal colonization by different bacterial pathogens. We therefore studied the influence of the human CEACAM1 receptor in human CEACAM1-transgenic mice on the C. albicans colonization and infection utilizing a colonization/dissemination and a systemic infection mouse model. Our results showed no alterations in the host response between the transgenic mice and the wild-type littermates to the C. albicans infections. Both mouse strains showed comparable C. albicans colonization and mycobiota, similar fungal burdens in various organs, and a similar survival in the systemic infection model. Interestingly, some of the mice treated with anti-bacterial antibiotics (to prepare them for C. albicans colonization via oral infection) also showed a strong reduction in endogenous fungi instead of the normally observed increase in fungal numbers. This was independent of the expression of human CEACAM1. In the systemic infection model, the human CEACAM1 expression was differentially regulated in the kidneys and livers of Candida-infected transgenic mice. Notably, in the kidneys, a total loss of the largest human CEACAM1 isoform was observed. However, the overwhelming immune response induced in the systemic infection model likely covered any CEACAM1-specific effects in the transgenic animals. In vitro studies using bone marrow-derived neutrophils from both mouse strains also revealed no differences in their reaction to C. albicans. In conclusion, in contrast to bacterial pathogens interacting with CEACAM1 on different mucosal surfaces, the human CEACAM1-transgenic mice did not reveal a role of human CEACAM1 in the in vivo candidiasis models used here. Further studies and different approaches will be needed to reveal a putative role of CEACAM1 in the host response to C. albicans.

Controlling intestinal colonization of high-risk haematology patients with ESBL-producing Enterobacteriaceae: a randomized, placebo-controlled, multicentre, Phase II trial (CLEAR).

OBJECTIVES: We assessed the efficacy and safety of an oral antimicrobial regimen for short- and long-term intestinal eradication of ESBL-producing Escherichia coli and Klebsiella pneumoniae (ESBL-EC/KP) in immunocompromised patients. METHODS: We performed a randomized (2:1), double-blind multicentre Phase II study in four haematology-oncology departments. Patients colonized with ESBL-EC/KP received a 7 day antimicrobial regimen of oral colistin (2 × 106 IU 4×/day), gentamicin (80 mg 4×/day) and fosfomycin (three administrations of 3 g every 72 h), or placebo. Faecal, throat and urine specimens were collected on day 0, 6 ± 2, 11 ± 2, 28 ± 4 and 42 ± 4 after treatment initiation, and the quantitative burden of ESBL-EC/KP, resistance genes and changes in intestinal microbiota were analysed. Clinicaltrials.gov: NCT01931592. RESULTS: As the manufacture of colistin powder was suspended worldwide, the study was terminated prematurely. Overall, 29 (18 verum/11 placebo) out of 47 patients were enrolled. The short-term intestinal eradication was marginal at day 6 (verum group 15/18, 83.3% versus placebo 2/11, 18.2%; relative risk 4.58, 95% CI 1.29-16.33; Fisher's exact test P = 0.001) and not evident at later timepoints. Quantitative analysis showed a significant decrease of intestinal ESBL-EC/KP burden on day 6. Sustained intestinal eradication (day 28 + 42) was not achieved (verum, 38.9% versus placebo, 27.3%; P = 0.299). In the verum group, mcr-1 genes were detected in two faecal samples collected after treatment. Microbiome analysis showed a significant decrease in alpha diversity and a shift in beta diversity. CONCLUSIONS: In this prematurely terminated study of a 7 day oral antimicrobial eradication regimen, short-term ESBL-EC/KP suppression was marginal, while an altered intestinal microbiota composition was clearly apparent.

AmpliSeq Screening of Genes Encoding the C-Type Lectin Receptors and Their Signaling Components Reveals a Common Variant in MASP1 Associated with Pulmonary Tuberculosis in an Indian Population.

Tuberculosis (TB) is a multifactorial disease governed by bacterial, host and environmental factors. On the host side, growing evidence shows the crucial role that genetic variants play in the susceptibility to Mycobacterium tuberculosis (Mtb) infection. Such polymorphisms have been described in genes encoding for different cytokines and pattern recognition receptors (PRR), including numerous Toll-like receptors (TLRs). In recent years, several members of the C-type lectin receptors (CTLRs) have been identified as key PRRs in TB pathogenesis. Nevertheless, studies to date have only addressed particular genetic polymorphisms in these receptors or their related pathways in relation with TB. In the present study, we screened the main CTLR gene clusters as well as CTLR pathway-related genes for genetic variation associated with pulmonary tuberculosis (PTB). This case-control study comprised 144 newly diagnosed pulmonary TB patients and 181 healthy controls recruited at the Bhagwan Mahavir Medical Research Center (BMMRC), Hyderabad, India. A two-stage study was employed in which an explorative AmpliSeq-based screening was followed by a validation phase using iPLEX MassARRAY. Our results revealed one SNP (rs3774275) in MASP1 significantly associated with PTB in our population (joint analysis p = 0.0028). Furthermore, serum levels of MASP1 were significantly elevated in TB patients when compared to healthy controls. Moreover, in the present study we could observe an impact of increased MASP1 levels on the lectin pathway complement activity in vitro. In conclusion, our results demonstrate a significant association of MASP1 polymorphism rs3774275 and MASP1 serum levels with the development of pulmonary TB. The present work contributes to our understanding of host-Mtb interaction and reinforces the critical significance of mannose-binding lectin and the lectin-complement pathway in Mtb pathogenesis. Moreover, it proposes a MASP1 polymorphism as a potential genetic marker for TB resistance.

Differential regulation of the transcriptomic and secretomic landscape of sensor and effector functions of human airway epithelial cells.

Protein secretion upon TLR, TNFR1, and IFNGR ligation in the human airways is considered to be central for the orchestration of pulmonary inflammatory and immune responses. In this study, we compared the gene expression and protein secretion profiles in response to specific stimulation of all expressed TLRs and in further comparison to TNFR1 and IFNGR in primary human airway epithelial cells. In addition to 22 cytokines, we observed the receptor-induced regulation of 571 genes and 1,012 secreted proteins. Further analysis revealed high similarities between the transcriptional TLR sensor and TNFR1 effector responses. However, secretome to transcriptome comparisons showed a broad receptor stimulation-dependent release of proteins that were not transcriptionally regulated. Many of these proteins are annotated to exosomes with associations to, for example, antigen presentation and wound-healing, or were identified as secretable proteins related to immune responses. Thus, we show a hitherto unrecognized scope of receptor-induced responses in airway epithelium, involving several additional functions for the immune response, exosomal communication and tissue homeostasis.

IL-37 Causes Excessive Inflammation and Tissue Damage in Murine Pneumococcal Pneumonia.

Streptococcus pneumoniae infections can lead to severe complications with excessive immune activation and tissue damage. Interleukin-37 (IL-37) has gained importance as a suppressor of innate and acquired immunity, and its effects have been therapeutic as they prevent tissue damage in autoimmune and inflammatory diseases. By using RAW macrophages, stably transfected with human IL-37, we showed a 70% decrease in the cytokine levels of IL-6, TNF-α, and IL-1ß, and a 2.2-fold reduction of the intracellular killing capacity of internalized pneumococci in response to pneumococcal infection. In a murine model of infection with S. pneumoniae, using mice transgenic for human IL-37b (IL-37tg), we observed an initial decrease in cytokine expression of IL-6, TNF-α, and IL-1ß in the lungs, followed by a late-phase enhancement of pneumococcal burden and subsequent increase of proinflammatory cytokine levels. Additionally, a marked increase in recruitment of alveolar macrophages and neutrophils was noted, while TRAIL mRNA was reduced 3-fold in lungs of IL-37tg mice, resulting in necrotizing pneumonia with augmented death of infiltrating neutrophils, enhanced bacteremic spread, and increased mortality. In conclusion, we have identified that IL-37 modulates several core components of a successful inflammatory response to pneumococcal pneumonia, which lead to increased inflammation, tissue damage, and mortality.

Global analysis of glycoproteins identifies markers of endotoxin tolerant monocytes and GPR84 as a modulator of TNFα expression.

Exposure of human monocytes to lipopolysaccharide (LPS) induces a temporary insensitivity to subsequent LPS challenges, a cellular state called endotoxin tolerance. In this study, we investigated the LPS-induced global glycoprotein expression changes of tolerant human monocytes and THP-1 cells to identify markers and glycoprotein targets capable to modulate the immunosuppressive state. Using hydrazide chemistry and LC-MS/MS analysis, we analyzed glycoprotein expression changes during a 48 h LPS time course. The cellular snapshots at different time points identified 1491 glycoproteins expressed by monocytes and THP-1 cells. Label-free quantitative analysis revealed transient or long-lasting LPS-induced expression changes of secreted or membrane-anchored glycoproteins derived from intracellular membrane coated organelles or from the plasma membrane. Monocytes and THP-1 cells demonstrated marked differences in glycoproteins differentially expressed in the tolerant state. Among the shared differentially expressed glycoproteins G protein-coupled receptor 84 (GPR84) was identified as being capable of modulating pro-inflammatory TNFα mRNA expression in the tolerant cell state when activated with its ligand Decanoic acid.

Binding of Candida albicans to Human CEACAM1 and CEACAM6 Modulates the Inflammatory Response of Intestinal Epithelial Cells.

Candida albicans colonizes human mucosa, including the gastrointestinal tract, as a commensal. In immunocompromised patients, C. albicans can breach the intestinal epithelial barrier and cause fatal invasive infections. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1; CD66a), CEACAM5 (CEA), and CEACAM6 (CD66c) are immunomodulatory receptors expressed on human mucosa and are recruited by bacterial and viral pathogens. Here we show for the first time that a fungal pathogen (i.e., C. albicans) also binds directly to the extracellular domain of human CEACAM1, CEACAM3, CEACAM5, and CEACAM6. Binding was specific for human CEACAMs and mediated by the N-terminal IgV-like domain. In enterocytic C2BBe1 cells, C. albicans caused a transient tyrosine phosphorylation of CEACAM1 and induced higher expression of membrane-bound CEACAM1 and soluble CEACAM6. Lack of the CEACAM1 receptor after short hairpin RNA (shRNA) knockdown abolished CXCL8 (interleukin-8) secretion by C2BBe1 cells in response to C. albicans In CEACAM1-competent cells, the addition of recombinant soluble CEACAM6 reduced the C. albicans-induced CXCL8 secretion.IMPORTANCE The present study demonstrates for the first time that fungal pathogens can be recognized by at least four members of the immunomodulatory CEACAM receptor family: CEACAM1, -3, -5, and -6. Three of the four receptors (i.e., CEACAM1, -5, and -6) are expressed in mucosal cells of the intestinal tract, where they are implicated in immunomodulation and control of tissue homeostasis. Importantly, the interaction of the major fungal pathogen in humans Candida albicans with CEACAM1 and CEACAM6 resulted in an altered epithelial immune response. With respect to the broad impact of CEACAM receptors on various aspects of the innate and the adaptive immune responses, in particular epithelial, neutrophil, and T cell behavior, understanding the role of CEACAMs in the host response to fungal pathogens might help to improve management of superficial and systemic fungal infections.

S100A12 is up-regulated in pulmonary tuberculosis and predicts the extent of alveolar infiltration on chest radiography: an observational study.

Pulmonary tuberculosis (PTB) results in lung functional impairment and there are no surrogate markers to monitor the extent of lung involvement. We investigated the clinical significance of S100A12 and soluble receptor for advanced glycation end-products (sRAGE) for predicting the extent of lung involvement. We performed an observational study in India with 119 newly diagnosed, treatment naïve, sputum smear positive, HIV-negative PTB patients and 163 healthy controls. All patients were followed-up for six months. Sociodemographic variables and the serum levels of S100A12, sRAGE, esRAGE, HMGB-1, TNF-α, IFN-γ and CRP were measured. Lung involvement in PTB patients was assessed by chest radiography. Compared with healthy controls, PTB patients had increased serum concentrations of S100A12 while sRAGE was decreased. S100A12 was an independent predictor of disease occurrence (OR 1.873, 95%CI 1.212-2.891, p = 0.004). Under DOTS therapy, S100A12 decreased significantly after 4 months whereas CRP significantly decreased after 2 months (p < 0.0001). Importantly, although CRP was also an independent predictor of disease occurrence, only S100A12 was a significant predictor of lung alveolar infiltration (OR 2.60, 95%CI 1.35-5.00, p = 0.004). These results suggest that S100A12 has the potential to assess the extent of alveolar infiltration in PTB.

Moraxella catarrhalis decreases antiviral innate immune responses by down-regulation of TLR3 via inhibition of p53 in human bronchial epithelial cells.

Chronic obstructive pulmonary disease (COPD) is complicated by infectious exacerbations with acute worsening of respiratory symptoms. Coinfections of bacterial and viral pathogens are associated with more severe exacerbations. Moraxella catarrhalis is one of the most frequent lower respiratory tract pathogens detected in COPD. We therefore studied the impact of M. catarrhalis on the antiviral innate immune response that is mediated via TLR3 and p53. Molecular interactions between M. catarrhalis and normal human bronchial epithelial (NHBE) cells as well as Beas-2B cells were studied using flow cytometry, quantitative PCR analysis, chromatin immunoprecipitation, RNA interference, and ELISA. M. catarrhalis induces a significant down-regulation of TLR3 in human bronchial epithelial cells. In M. catarrhalis-infected cells, expression of p53 was decreased. We detected a reduced binding of p53 to the tlr3 promoter, resulting in reduced TLR3 gene transcription. M. catarrhalis diminished the TLR3-dependent secretion of IFN-ß, IFN-λ, and chemokine (C-X-C motif) ligand 8. In addition in M. catarrhalis infected cells, expression of rhinovirus type 1A RNA was increased compared with uninfected cells. M. catarrhalis reduces antiviral defense functions of bronchial epithelial cells, which may increase susceptibility to viral infections.-Heinrich, A., Haarmann, H., Zahradnik, S., Frenzel, K., Schreiber, F., Klassert, T. E., Heyl, K. A., Endres, A.-S., Schmidtke, M., Hofmann, J., Slevogt, H. Moraxella catarrhalis decreases antiviral innate immune responses by down-regulation of TLR3 via inhibition of p53 in human bronchial epithelial cells.

Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury.

Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The 'response to microorganisms' was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the 'neuron projection morphogenesis' process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis', which have been never anticipated in ALI pathogenesis, promotes lung-protective effects of LVT with high levels of PEEP.

Dectin-1 is expressed in human lung and mediates the proinflammatory immune response to nontypeable Haemophilus influenzae.

UNLABELLED: The C-type lectin receptor Dectin-1 is expressed mainly on myeloid cells mediating the immune response targeting respiratory pathogens such as Aspergillus fumigatus and Mycobacterium tuberculosis. The pulmonary epithelium serves as an important interface for interactions between these pathogens and the respiratory tract. Therefore, we analyzed the expression pattern of Dectin-1 in the human lung. Immunohistochemically stained human lung sections from 17 out of 19 individuals were positive for Dectin-1, which was expressed mainly apically on bronchial and alveolar epithelium. Our results showed no correlation with chronic obstructive pulmonary disease (COPD) or the smoking habits of the patients. Nontypeable Haemophilus influenzae (NTHI), an important bacterial pathogen of the respiratory tract with significant importance in COPD, has also been proposed to be recognized by Dectin-1, suggesting a possible impact on the NTHI-dependent immune response in human airways. Therefore, the involvement of Dectin-1 in NTHI-triggered cytokine responses was investigated in primary normal human bronchial epithelial (NHBE) cells and in the A549 cell line stably transfected with Dectin-1. The presence of Dectin-1 significantly increased cytokine release in response to NTHI in NHBE and A549 cells. In addition, phosphorylation of the Dectin-1 hem-immunoreceptor tyrosine-based activation motif (hemITAM) was essential for the Dectin-1-triggered response to NTHI in A549 cells. In conclusion, in human airways, epithelium-expressed Dectin-1 may play a significant role in generating an NTHI-mediated, proinflammatory immune response. IMPORTANCE: In this study, we demonstrated, for the first time, the expression of Dectin-1 on human lung tissues and, in particular, pulmonary epithelium by making use of immunohistochemical staining. The epithelial lining of the human airways is an important interface for host-pathogen interactions. Therefore, our data suggest that epithelium-expressed Dectin-1 is of considerable importance for the interaction of the human airways with pathogens detected by this receptor, such as A. fumigatus and M. tuberculosis. Moreover, we further demonstrated that, in pulmonary epithelial cells, Dectin-1 enhances the proinflammatory immune response to NTHI. In COPD patients, NTHI is a major cause of respiratory tract infections and is associated with proinflammatory immune responses in the lower airways. Therefore, our data suggest that the functional interaction of Dectin-1 with NTHI in human airways may have an important impact on the pathogenesis of COPD.

Carcinoembryonic antigen (CEA)-related cell adhesion molecules are co-expressed in the human lung and their expression can be modulated in bronchial epithelial cells by non-typable Haemophilus influenzae, Moraxella catarrhalis, TLR3, and type I and II interferons.

BACKGROUND: The carcinoembryonic antigen (CEA)-related cell adhesion molecules CEACAM1 (BGP, CD66a), CEACAM5 (CEA, CD66e) and CEACAM6 (NCA, CD66c) are expressed in human lung. They play a role in innate and adaptive immunity and are targets for various bacterial and viral adhesins. Two pathogens that colonize the normally sterile lower respiratory tract in patients with chronic obstructive pulmonary disease (COPD) are non-typable Haemophilus influenzae (NTHI) and Moraxella catarrhalis. Both pathogens bind to CEACAMs and elicit a variety of cellular reactions, including bacterial internalization, cell adhesion and apoptosis. METHODS: To analyze the (co-) expression of CEACAM1, CEACAM5 and CEACAM6 in different lung tissues with respect to COPD, smoking status and granulocyte infiltration, immunohistochemically stained paraffin sections of 19 donors were studied. To address short-term effects of cigarette smoke and acute inflammation, transcriptional regulation of CEACAM5, CEACAM6 and different CEACAM1 isoforms by cigarette smoke extract, interferons, Toll-like receptor agonists, and bacteria was tested in normal human bronchial epithelial (NHBE) cells by quantitative PCR. Corresponding CEACAM protein levels were determined by flow cytometry. RESULTS: Immunohistochemical analysis of lung sections showed the most frequent and intense staining for CEACAM1, CEACAM5 and CEACAM6 in bronchial and alveolar epithelium, but revealed no significant differences in connection with COPD, smoking status and granulocyte infiltration. In NHBE cells, mRNA expression of CEACAM1 isoforms CEACAM1-4L, CEACAM1-4S, CEACAM1-3L and CEACAM1-3S were up-regulated by interferons alpha, beta and gamma, as well as the TLR3 agonist polyinosinic:polycytidylic acid (poly I:C). Interferon-gamma also increased CEACAM5 expression. These results were confirmed on protein level by FACS analysis. Importantly, also NTHI and M. catarrhalis increased CEACAM1 mRNA levels. This effect was independent of the ability to bind to CEACAM1. The expression of CEACAM6 was not affected by any treatment or bacterial infection. CONCLUSIONS: While we did not find a direct correlation between CEACAM1 expression and COPD, the COPD-associated bacteria NTHi and M. catarrhalis were able to increase the expression of their own receptor on host cells. Further, the data suggest a role for CEACAM1 and CEACAM5 in the phenomenon of increased host susceptibility to bacterial infection upon viral challenge in the human respiratory tract.

Developmental regulation of TAC1 in peptidergic-induced human mesenchymal stem cells: implication for spinal cord injury in zebrafish.

Human mesenchymal stem cells (MSCs) are easy to expand, are relatively safe, and can be transplanted in allogeneic recipients as off-the-shelf cells. MSCs can be induced to form functional peptidergic neurons and express the neurotransmitter gene, TAC1. Expression of TAC1 requires that the repressor gene, RE-1 silencing transcription factor (REST), is decreased. This study investigated the molecular pathway in TAC1 induction as MSCs differentiated into neurons and then applied the findings in a model of spinal cord injury (SCI) in zebrafish. We studied the developmental roles of the 2 cAMP response element (CRE) sites: CRE1 and CRE2. Activator protein-1 (AP-1) binding site overlaps with CRE2 (CRE2/AP-1). Reporter gene studies with the 5' regulatory region of TAC1 containing wild-type or mutant CRE sites and, parallel studies with ectopically expressed inhibitor of cAMP proteins (inducible cAMP early repressor) indicated that CRE1 and CRE2/AP-1 are activated at days 6 and 12, respectively. Studies with protein kinase-A (PKA) and Jun N-terminal kinase (JNK) inhibitors in the reporter gene studies, chromatin immunoprecipation assay, and ectopic expression of REST indicated the following pathways: Decrease of REST activated upstream c-Jun N-terminal kinase (JNK). In turn, JNK activated ATF-2 and AP-1 for interaction with CRE1 and CRE2/AP-1, respectively. To apply the finding to SCI, we transplanted 6-day-induced MSCs in transgenic HB9-GFP zebrafish larvae with SCI, in the presence or absence of JNK inhibitors. Imaging and functional studies showed significant improvement in the fish. The repair mechanism involved the activation of JNK. The findings have long-term implications for SCI repair with MSCs.

Tachykinins and Neurokinin Receptors in Bone Marrow Functions: Neural-Hematopoietic Link.

After many decades of neuropeptide research, advances in the field of tachykinins have considerably increased and shown their implications in several physiological processes. In this review we focus on the role of the tachykinins in the regulation of hematopoietic functions. Evidence has shown that neural control of this process is emerging as a significant category in hematopoietic modulation. In the context of this regulation, we discuss the existence of a complex network involving the neurokinin receptors, tachykinins and cytokines. This network is tightly regulated by each of its components.