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

Neisseriae internalization by epithelial cells is enhanced by TLR2 stimulation

Neisseria meningitidis (NM) is an opportunistic gram-negative human pathogen that colonizes the human nasopharyngeal epithelium. Asymptomatic carriage is common, but some meningococcal strains can invade nasopharyngeal epithelial cells and proceed to cause severe and often fatal infections. Invasion is predominantly driven by expression of bacterial virulence factors and host cell cognate receptors for bacterial recognition. Porins are among the Neisserial components involved in host cell activation and bacterial internalization processes. Similar to other virulence factors, porins present antigenic and structure variability among strains. Such sequence variability in the surface-exposed loop regions has been correlated to bacterial invasiveness and to variability in host cell responses via Toll-like receptor 2 (TLR2). Here, we examined whether TLR2 signaling by porins influences recovery of intracellular Neisseriae from epithelial cells in vitro. Our results show that TLR2 stimulation, either by the organism or exogenously, generally enhances Neisseriae internalization by epithelial cells. TLR2-driven intracellular signaling via ERK1/2, JNK and particularly NF-κB plays a role in this process. Based on these results, it is possible that expression of porin sequence variants that strongly induce TLR2 activation may be a mechanism to enhance the invasive features of pathogenic Neisseriae strains.

Dual RNA-seq of Nontypeable Haemophilus influenzae and Host Cell Transcriptomes Reveals Novel Insights into Host-Pathogen Cross Talk

The ability to adhere and adapt to the human respiratory tract mucosa plays a pivotal role in the pathogenic lifestyle of nontypeable Haemophilus influenzae (NTHi). However, the temporal events associated with a successful colonization have not been fully characterized. In this study, by reconstituting the ciliated human bronchial epithelium in vitro, we monitored the global transcriptional changes in NTHi and infected mucosal epithelium simultaneously for up to 72 h by dual RNA sequencing. The initial stage of colonization was characterized by the binding of NTHi to ciliated cells. Temporal profiling of host mRNA signatures revealed significant dysregulation of the target cell cytoskeleton elicited by bacterial infection, with a profound effect on the intermediate filament network and junctional complexes. In response to environmental stimuli of the host epithelium, NTHi downregulated its central metabolism and increased the expression of transporters, indicating a change in the metabolic regime due to the availability of host substrates. Concurrently, the oxidative environment generated by infected cells instigated bacterial expression of stress-induced defense mechanisms, including the transport of exogenous glutathione and activation of the toxin-antitoxin system. The results of this analysis were validated by those of confocal microscopy, Western blotting, Bio-plex, and real-time quantitative reverse transcription-PCR (qRT-PCR). Notably, as part of our screening for novel signatures of infection, we identified a global profile of noncoding transcripts that are candidate small RNAs (sRNAs) regulated during human host infection in Haemophilus species. Our data, by providing a robust and comprehensive representation of the cross talk between the host and invading pathogen, provides important insights into NTHi pathogenesis and the development of efficacious preventive strategies.

IMPORTANCE

Simultaneous monitoring of infection-linked transcriptome alterations in an invading pathogen and its target host cells represents a key strategy for identifying regulatory responses that drive pathogenesis. In this study, we report the progressive events of NTHi colonization in a highly differentiated model of ciliated bronchial epithelium. Genome-wide transcriptome maps of NTHi during infection provided mechanistic insights into bacterial adaptive responses to the host niche, with modulation of the central metabolism as an important signature of the evolving milieu. Our data indicate that infected epithelia respond by substantial alteration of the cytoskeletal network and cytokine repertoire, revealing a dynamic cross talk that is responsible for the onset of inflammation. This work significantly enhances our understanding of the means by which NTHi promotes infection on human mucosae and reveals novel strategies exploited by this important pathogen to cause invasive disease.

Nontypeable Haemophilus influenzae exploits the interaction between protein-E and vitronectin for the adherence and invasion to bronchial epithelial cells

Background

Nontypeable Haemophilus influenzae (NTHi) is one of the most common Gram-negative pathogens in otitis media and exacerbation of chronic obstructive pulmonary disease. NTHi has been reported to invade bronchial epithelial cells. This penetration enables NTHi to evade the host immune system and antibiotics, and it seems to be related to the intractable features of these diseases. However, the precise mechanism of the invasion has been unknown. We hypothesized that protein-E, an outer membrane protein of NTHi, plays a role in this penetration into bronchial epithelial cells.

Results

We utilized two NTHi strains. NTHi efficiently attached to plate-bound vitronectin (254–309 / field at 1,000× magnification) and this attachment was blocked by pretreatment with protein-E peptide (PE^84–108). The blockade of adhesion was dependent on the concentration of PE^84–108. NTHi strains invaded bronchial epithelial cells and the intracellular bacteria were localized in early endosomes. Furthermore, intracellular invasion of NTHi was also blocked by PE^84–108, but not by Arg-Gly-Asp (RGD) peptide. Pretreatment with PE^84–108 significantly prevented cells from being invaded by both NTHi strains, which was confirmed by fluorescent microscope observation. In addition, pretreatment with PE^84–108 significantly reduced percentages of CFU after gentamicin treatment of cells per input CFU.

Conclusions

These results suggest that NTHi does not directly bind to the cell surface, but binds to host vitronectin that is bound to the cell surface, via bacterial protein-E. Bacterial protein-E and host vitronectin play a role in the attachment to bronchial epithelial cells and is also involved in the subsequent intracellular invasion of NTHi. A novel vaccine or treatment strategy targeting the protein-E-vitronectin axis may prevent respiratory intracellular infection of NTHi and may lead to better clinical outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0600-8) contains supplementary material, which is available to authorized users.

Therapeutic effect of anti CEACAM6 monoclonal antibody against lung adenocarcinoma by enhancing anoikis sensitivity

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) plays a crucial role in tumorigenesis of lung cancer. However, the therapeutic potential for anti CEACAM6 monoclonal antibody (mAb) has only been limitedly explored. Here, we evaluate the therapeutic potential of naked anti CEACAM6 mAb against lung adenocarcinoma. Clone 8F5, recognizing B domain of CEACAM6, is established by immunizing A549 cells and screening for clones double positive for A549 and CEACAM6-Fc recombinant protein. We found that 85.7% of 70 resected lung adenocarcinoma tissue sections were positive for CEACAM6, whereas all squamous cell carcinoma examined were negative. A549 cells with high levels of CEACAM6 demonstrated more aggressive growth nature and showed increased paclitaxel chemosensitivity upon 8F5 binding. Treatment with 8F5 to A549 decreased cellular CEACAM6 expression and reversed anoikis resistance. 8F5 also decreased cellular status of Akt phosphorylation and increased apoptosis via caspase activation. In a mouse model of lung adenocarcinoma with xenotransplanted A549 cells, 8F5 treatment alone demonstrated 40% tumor growth inhibition. When combined with paclitaxel treatment, 8F5 markedly enhanced tumor growth inhibition, up to 80%. In summary, we demonstrate that anti CEACAM6 mAb is an effective therapeutic treatment for lung adenocarcinoma whose effect is further enhanced by combined treatment with paclitaxel.

Moraxella catarrhalis induces an immune response in the murine lung that is independent of human CEACAM5 expression and long-term smoke exposure

In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared with wild-type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5 expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.

Pathogenesis of progressive scarring trachoma in Ethiopia and Tanzania and its implications for disease control: two cohort studies

BACKGROUND

Trachoma causes blindness through a conjunctival scarring process initiated by ocular Chlamydia trachomatis infection; however, the rates, drivers and pathophysiological determinants are poorly understood. We investigated progressive scarring and its relationship to conjunctival infection, inflammation and transcript levels of cytokines and fibrogenic factors.

METHODOLOGY/PRINCIPAL FINDINGS

We recruited two cohorts, one each in Ethiopia and Tanzania, of individuals with established trachomatous conjunctival scarring. They were followed six-monthly for two years, with clinical examinations and conjunctival swab sample collection. Progressive scarring cases were identified by comparing baseline and two-year photographs, and compared to individuals without progression. Samples were tested for C. trachomatis by PCR and transcript levels of S100A7, IL1B, IL13, IL17A, CXCL5, CTGF, SPARCL1, CEACAM5, MMP7, MMP9 and CD83 were estimated by quantitative RT-PCR. Progressive scarring was found in 135/585 (23.1%) of Ethiopian participants and 173/577 (30.0%) of Tanzanian participants. There was a strong relationship between progressive scarring and increasing inflammatory episodes (Ethiopia: OR 5.93, 95%CI 3.31-10.6, p<0.0001. Tanzania: OR 5.76, 95%CI 2.60-12.7, p<0.0001). No episodes of C. trachomatis infection were detected in the Ethiopian cohort and only 5 episodes in the Tanzanian cohort. Clinical inflammation, but not scarring progression, was associated with increased expression of S100A7, IL1B, IL17A, CXCL5, CTGF, CEACAM5, MMP7, CD83 and reduced SPARCL1.

CONCLUSIONS/SIGNIFICANCE

Scarring progressed in the absence of detectable C. trachomatis, which raises uncertainty about the primary drivers of late-stage trachoma. Chronic conjunctival inflammation appears to be central and is associated with enriched expression of pro-inflammatory factors and altered expression of extracellular matrix regulators. Host determinants of scarring progression appear more complex and subtle than the features of inflammation. Overall this indicates a potential role for anti-inflammatory interventions to interrupt progression and the need for trichiasis disease surveillance and surgery long after chlamydial infection has been controlled at community level.

Cell surface marker profiling of human tracheal basal cells reveals distinct subpopulations, identifies MST1/MSP as a mitogenic signal, and identifies new biomarkers for lung squamous cell carcinomas

BACKGROUND

The large airways of the lungs (trachea and bronchi) are lined with a pseudostratified mucociliary epithelium, which is maintained by stem cells/progenitors within the basal cell compartment. Alterations in basal cell behavior can contribute to large airway diseases including squamous cell carcinomas (SQCCs). Basal cells have traditionally been thought of as a uniform population defined by basolateral position, cuboidal cell shape, and expression of pan-basal cell lineage markers like KRT5 and TP63. While some evidence suggests that basal cells are not all functionally equivalent, few heterogeneously expressed markers have been identified to purify and study subpopulations. In addition, few signaling pathways have been identified that regulate their cell behavior. The goals of this work were to investigate tracheal basal cell diversity and to identify new signaling pathways that regulate basal cell behavior.

METHODS

We used flow cytometry (FACS) to profile cell surface marker expression at a single cell level in primary human tracheal basal cell cultures that maintain stem cell/progenitor activity. FACS results were validated with tissue staining, in silico comparisons with normal basal cell and lung cancer datasets, and an in vitro proliferation assay.

RESULTS

We identified 105 surface markers, with 47 markers identifying potential subpopulations. These subpopulations generally fell into more (~ > 13%) or less abundant (~ < 6%) groups. Microarray gene expression profiling supported the heterogeneous expression of these markers in the total population, and immunostaining of large airway tissue suggested that some of these markers are relevant in vivo. 24 markers were enriched in lung SQCCs relative to adenocarcinomas, with four markers having prognostic significance in SQCCs. We also identified 33 signaling receptors, including the MST1R/RON growth factor receptor, whose ligand MST1/MSP was mitogenic for basal cells.

CONCLUSION

This work provides the largest description to date of molecular diversity among human large airway basal cells. Furthermore, these markers can be used to further study basal cell function in repair and disease, and may aid in the classification and study of SQCCs.

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

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.

Deep transcriptome sequencing of Pecten maximus hemocytes: a genomic resource for bivalve immunology

Pecten maximus, the king scallop, is a bivalve species with important commercial value for both fisheries and aquaculture, traditionally consumed in several European countries. Major problems in larval rearing, however, still limit hatchery-based seed production. High mortalities during early larval stages, likely related to bacterial pathogens, represent the most relevant bottleneck. To address this issue, understanding host defense mechanisms against microbes is extremely important. In this study next-generation RNA-sequencing was carried on scallop hemocytes. To enrich for immune-related transcripts, cDNA libraries from hemocytes challenged in vivo with inactivated-Vibrio anguillarum and in vitro with pathogen-associated molecular patterns, as well as unchallenged controls, were sequenced yielding 216,444,674 sequence reads. De novo assembly of the scallop hemocyte transcriptome consisted of 73,732 contigs (31% annotated). A total of 934 contigs encoded proteins with a known immune function, grouped into several functional categories. Particular attention was reserved to Toll-like receptors (TLRs), a family of pattern recognition receptors (PRRs) involved in non-self recognition. Through mining the scallop hemocyte transcriptome, at least four TLRs could be identified. The organization of canonical TLR domains demonstrated that single cysteine cluster and multiple cysteine cluster TLRs co-exist in this species. In addition, preliminary data concerning their mRNA level following bacterial challenge suggested that different members of this family could exhibit opposite responses to pathogenic stimuli. Finally, a global analysis of differential expression comparing gene-expression levels in in vitro and in vivo stimulated hemocytes against controls provided evidence on a large set of transcripts involved in the great scallop immune response.