Immunomodulatory roles of the carcinoembryonic antigen family of glycoproteins

Role of eosinophil counts in mediating the association between asthma and colon cancer

BACKGROUND

Epidemiological findings regarding the association between asthma and the risk of colon cancer (CC) are inconsistent. The causality and potential molecular mechanisms underlying asthma, eosinophil count, and CC remain unknown.

METHODS

We performed Mendelian randomization (MR) analysis to investigate the causality between asthma and CC and attempted to demonstrate that asthma indirectly affects CC mediated by eosinophil count through mediation analysis. Sensitivity analyses and multivariable MR were performed to test the robustness of our findings. Multiple bioinformatics tools were applied to further investigate the underlying mechanisms related to eosinophils that contribute to the pathogenesis of both asthma and CC.

RESULTS

MR with mediation analyses suggested that eosinophil count may play a role in the mechanism through which asthma reduces the risk of CC. Our bioinformatic analyses identified PPP1R14A as a potential therapeutic target and an eosinophil-associated biomarker for CC patients. Higher expression of PPP1R14A may be associated with a poorer prognosis in CC patients. Additionally, the lysosome pathway emerges as a shared eosinophil-related pathway in both asthma and CC.

CONCLUSIONS

Eosinophils may contribute to a lower risk of CC in patients with asthma. PPP1R14A is a potential therapeutic target and biomarker for CC.

Biomarker screening in fetal growth restriction based on multiple RNA-seq studies

Objective

Fetal growth restriction (FGR) is a severe pathological complication associated with compromised fetal development. The early diagnosis and prediction for FGR are still unclear. Sequencing technologies present a huge opportunity to identify novel biomarkers. However, limitation of individual studies (e.g., long lists of dysregulated genes, small sample size and conflicting results) hinders the selection of the best-matched ones.

Study design

A multi-step bioinformatics analysis was performed. We separately reanalyzed data from four public RNA-seq studies, followed by a combined analysis of individual results. The differentially expressed genes (DEGs) were identified based on DESeq2. Then, function enrichment analyses and protein-protein interaction network (PPI) were conducted to screen for hub genes. The results were further verified by using external microarray data.

Results

A total of 65 dysregulated genes (50 down and 15 upregulated) were identified in FGR compared to controls. Function enrichment and PPI analysis revealed ten hub genes closely related to FGR. Validation analysis found four downregulated candidate biomarkers (CEACAM6, SCUBE2, DEFA4, and MPO) for FGR.

Conclusions

The use of omics tools to explore mechanism of pregnancies disorders contributes to improvements in obstetric clinical practice.

Regulation of CEACAM Family Members by IBD-Associated Triggers in Intestinal Epithelial Cells, Their Correlation to Inflammation and Relevance to IBD Pathogenesis

Carcinoembryogenic antigen cellular adhesion molecules (CEACAMs) are intercellular adhesion molecules highly expressed in intestinal epithelial cells. CEACAM1, -3, -5, -6, -7 are altered in patients suffering from colon cancer and inflammatory bowel diseases (IBD), but their role in the onset and pathogenesis of IBD is not well known. Herein, we aim to correlate CEACAM1, -3, -5, -6, -7 expression to the degree of inflammation in pediatric and adult IBD colon biopsies and to examine the regulation of CEACAMs on human intestinal epithelial cell lines (C2BBe1/HT29) by different IBD-associated triggers (cytokines, bacteria/metabolites, emulsifiers) and IBD-drugs (6-Mercaptopurine, Prednisolone, Tofacitinib). Biopsies from patients with pediatric Crohn’s disease (CD) and adult ulcerative colitis (UC, active/inactive disease) showed a significant increase in CEACAM3, -5, -6 expression, while CEACAM5 expression was reduced in adult CD patients (active/inactive disease). Intestinal epithelial cells cultured with a pro-inflammatory cytokine cocktail and Adherent-invasive Escherichia coli (AIEC) showed a rapid induction of CEACAM1, -5, -7 followed by a reduced RNA and protein expression overtime and a constant expression of CEACAM3, correlating with IL-8 expression. Cells cultured with the emulsifier polysorbate-80 resulted in a significant induction of CEACAM3, -5, -6, -7 at a late time point, while SCFA treatment reduced CEACAM1, -5, -7 expression. No major alterations in expression of CEACAMs were noted on cells cultured with the commensal Escherichia coli K12 or the pathogen Salmonella typhimurium. IBD drugs, particularly Tofacitinib, significantly reduced cytokine-induced CEACAM1, -3, -5, -6, -7 expression associated with a reduced IL-8 secretion. In conclusion, we provide new evidence on the regulation of CEACAMs by different IBD-associated triggers, identifying a role of CEACAMs in IBD pathogenesis.

Exploring the Triple Interaction between the Host Genome, the Epigenome, and the Gut Microbiome in Type 1 Diabetes

Type 1 diabetes (T1D) is an auto-immune disorder characterized by a complex interaction between the host immune system and various environmental factors in genetically susceptible individuals. Genome-wide association studies (GWAS) identified different T1D risk and protection alleles, however, little is known about the environmental factors that can be linked to these alleles. Recent evidence indicated that, among those environmental factors, dysbiosis (imbalance) in the gut microbiota may play a role in the pathogenesis of T1D, affecting the integrity of the gut and leading to systemic inflammation and auto-destruction of the pancreatic β cells. Several studies have identified changes in the gut microbiome composition in humans and animal models comparing T1D subjects with controls. Those changes were characterized by a higher abundance of Bacteroides and a lower abundance of the butyrate-producing bacteria such as Clostridium clusters IV and XIVa. The mechanisms by which the dysbiotic bacteria and/or their metabolites interact with the genome and/or the epigenome of the host leading to destructive autoimmunity is still not clear. As T1D is a multifactorial disease, understanding the interaction between different environmental factors such as the gut microbiome, the genetic and the epigenetic determinants that are linked with the early appearance of autoantibodies can expand our knowledge about the disease pathogenesis. This review aims to provide insights into the interaction between the gut microbiome, susceptibility genes, epigenetic factors, and the immune system in the pathogenesis of T1D.

Carcinoembryonic antigen cell adhesion molecule 6 (CEACAM6) in Pancreatic Ductal Adenocarcinoma (PDA): An integrative analysis of a novel therapeutic target

We investigated biomarker CEACAM6, a highly abundant cell surface adhesion receptor that modulates the extracellular matrix (ECM) in pancreatic ductal adenocarcinoma (PDA). The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) RNA-Seq data from PDA patients were analyzed for CEACAM6 expression and evaluated for overall survival, association, enrichment and correlations. A CRISPR/Cas9 Knockout (KO) of CEACAM6 in PDA cell line for quantitative proteomics, mitochondrial bioenergetics and tumor growth in mice were conducted. We found CEACAM6 is over-expressed in primary and metastatic basal and classical PDA subtypes. Highest levels are in classical activated stroma subtype. CEACAM6 over-expression is universally a poor prognostic marker in KRAS mutant and wild type PDA. High CEACAM6 expression is associated with low cytolytic T-cell activity in both basal and classical PDA subtypes and correlates with low levels of T-_REG markers. In HPAF-II cells knockout of CEACAM6 alters ECM-cell adhesion, catabolism, immune environment, transmembrane transport and autophagy. CEACAM6 loss increases mitochondrial basal and maximal respiratory capacity. HPAF-II CEACAM6−/− cells are growth suppressed by >65% vs. wild type in mice bearing tumors. CEACAM6, a key regulator affects several hallmarks of PDA including the fibrotic reaction, immune regulation, energy metabolism and is a novel therapeutic target in PDA.

Intestinal enteroids/organoids: A novel platform for drug discovery in inflammatory bowel diseases

The introduction of biologics such as anti-tumor necrosis factor (TNF) monoclonal antibodies followed by anti-integrins has dramatically changed the therapeutic paradigm of inflammatory bowel diseases (IBD). Furthermore, a newly developed anti-p40 subunit of interleukin (IL)-12 and IL-23 (ustekinumab) has been recently approved in the United States for patients with moderate to severe Crohn’s disease who have failed treatment with anti-TNFs. However, these immunosuppressive therapeutics which focus on anti-inflammatory mechanisms or immune cells still fail to achieve long-term remission in a significant percentage of patients. This strongly underlines the need to identify novel treatment targets beyond immune suppression to treat IBD. Recent studies have revealed the critical role of intestinal epithelial cells (IECs) in the pathogenesis of IBD. Physical, biochemical and immunologic driven barrier dysfunctions of epithelial cells contribute to the development of IBD. In addition, the recent establishment of adult stem cell-derived intestinal enteroid/organoid culture technology has allowed an exciting opportunity to study human IECs comprising all normal epithelial cells. This long-term epithelial culture model can be generated from endoscopic biopsies or surgical resections and recapitulates the tissue of origin, representing a promising platform for novel drug discovery in IBD. This review describes the advantages of intestinal enteroids/organoids as a research tool for intestinal diseases, introduces studies with these models in IBD, and gives a description of the current status of therapeutic approaches in IBD. Finally, we provide an overview of the current endeavors to identify a novel drug target for IBD therapy based on studies with human enteroids/organoids and describe the challenges in using enteroids/organoids as an IBD model.

Carcinoembryonic antigen (CEACAM) family members and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), is a chronic intestinal inflammatory condition with increasing incidence worldwide and whose pathogenesis remains largely unknown. The collected evidence indicates that genetic, environmental and microbial factors and a dysregulated immune response are responsible for the disease. IBD has an early onset and long term sufferers present a higher risk of developing colitis associated cancer (CAC). The carcinoembryonic antigen-related adhesion molecules (CEACAM) are a subgroup of the CEA family, found in a range of different cell types and organs including epithelial cells in the intestine. They can act as intercellular adhesions molecules for e.g. bacteria and soluble antigens. CEACAMs are involved in a number of different processes including cell adhesion, proliferation, differentiation and tumour suppression. Some CEACAMs such as CEACAM1, CEACAM5 and CEACAM6 are highly associated with cancer and are even recognised as valid clinical markers for certain cancer forms. However, their role in IBD pathogenesis is less understood. The purpose of this review is to provide a comprehensive summary of published literature on CEACAMs and intestinal inflammation (IBD). The interactions between CEACAMs and bacteria adhesion in relation to IBD pathophysiology will be addressed and potential new therapeutic and diagnostic opportunities will be identified.

Pathogenesis of human diffusely adhering Escherichia coli expressing Afa/Dr adhesins (Afa/Dr DAEC): current insights and future challenges

The pathogenicity and clinical pertinence of diffusely adhering Escherichia coli expressing the Afa/Dr adhesins (Afa/Dr DAEC) in urinary tract infections (UTIs) and pregnancy complications are well established. In contrast, the implication of intestinal Afa/Dr DAEC in diarrhea is still under debate. These strains are age dependently involved in diarrhea in children, are apparently not involved in diarrhea in adults, and can also be asymptomatic intestinal microbiota strains in children and adult. This comprehensive review analyzes the epidemiology and diagnosis and highlights recent progress which has improved the understanding of Afa/Dr DAEC pathogenesis. Here, I summarize the roles of Afa/Dr DAEC virulence factors, including Afa/Dr adhesins, flagella, Sat toxin, and pks island products, in the development of specific mechanisms of pathogenicity. In intestinal epithelial polarized cells, the Afa/Dr adhesins trigger cell membrane receptor clustering and activation of the linked cell signaling pathways, promote structural and functional cell lesions and injuries in intestinal barrier, induce proinflammatory responses, create angiogenesis, instigate epithelial-mesenchymal transition-like events, and lead to pks-dependent DNA damage. UTI-associated Afa/Dr DAEC strains, following adhesin-membrane receptor cell interactions and activation of associated lipid raft-dependent cell signaling pathways, internalize in a microtubule-dependent manner within urinary tract epithelial cells, develop a particular intracellular lifestyle, and trigger a toxin-dependent cell detachment. In response to Afa/Dr DAEC infection, the host epithelial cells generate antibacterial defense responses. Finally, I discuss a hypothetical role of intestinal Afa/Dr DAEC strains that can act as "silent pathogens" with the capacity to emerge as "pathobionts" for the development of inflammatory bowel disease and intestinal carcinogenesis.

CEACAM6 promotes tumor migration, invasion, and metastasis in gastric cancer

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) shows increased expression in a wide variety of human cancers, and its over-expression is associated with enhanced migration, invasion, and in vivo metastasis. Here, we reported that CEACAM6 was up-regulated in gastric cancer (GC) cell lines and tumor tissues. Over-expression of CEACAM6 in MKN-45 and SGC-7901 GC cells promoted migration and invasion in vitro and metastasis in athymic mice, whereas migration and invasion of MKN-28 and SNU-16 GC cells were suppressed by knockdown of CEACAM6. We also observed that steroid receptor coactivator (C-SRC) phosphorylation was increased when CEACAM6 was over-expressed in SGC-7901 cells. Taken together, these results suggested that CEACAM6 functions as an oncoprotein in GC and may be an important metastatic biomarker and therapeutic target.

[Immunotherapy for colorectal cancer]

Recent studies have underlined the close link between immune response and prognosis of patients with colorectal cancer (CRC). Immune response understanding combined with biotechnology progress of the last years has allowed development of immunotherapy strategies in CRC. Immunotherapy strategies are divided in "active" or "passive" strategies (patients immune system stimulation or not) and considering the activation of antigen specific immune response or not. These immunotherapy strategies are well tolerated and induced cellular and humoral response correlated with clinical response. Many monoclonal antibodies targeting signalisation pathways or angiogenic growth factors have demonstrated their efficacy in CRC. Multiple vaccine strategies, using different tumour associated antigens, have demonstrated a biological efficacy but with poor clinical results. Results are more promising in adjuvant setting but need to be confirmed by randomized trials. Adoptive immunotherapy with transfer of tumour associated antigen specific T cell is probably the most promising strategy. Actually, except monoclonal antibodies, immunotherapy is not used in clinical practice in CRC due to the lack of results and absence of standardisation.

Highly glycosylated tumour antigens: interactions with the immune system

A common phenotypic change in cancer is a dramatic transformation of cellular glycosylation. Functional studies of particular tumour-associated oligosaccharides are difficult to interpret conclusively, but carbohydrate-binding proteins are likely to contribute to progression of the tumour. This review discusses the potential role of CLRs (C-type lectin receptors), expressed by antigen-presenting cells of the immune system, in tumour recognition and immune modulation. Studies in recent years have provided significant insight into the immunomodulatory function of CLR during infections, but their role in cancer remains elusive; some strongly bind tumour cells and antigens, indicating participation in malignancy. The potential to use recombinant CLR as diagnostic tools will also be discussed.

Isolation of carcinoembryonic antigen N-terminal domains (N-A1) from soluble aggregates

Carcinoembryonic antigen (CEA) was identified as a prominent tumor-associated antigen in human colorectal cancer and it is still intensively investigated. However, its physiological role remains unclear. The CEA molecule is composed of seven highly hydrophobic, immunoglobulin-like domains, six of which contain a single disulphide bridge. The production of recombinant protein containing Ig-like domains in bacterial expression systems often results in partial degradation or insolubility due to aggregation hampering the analysis of their native structure and function. Here, we present a new method of expression and purification of CEA N-terminal domains (N-A1) fused to MBP in Escherichia coli. In order to optimize the expression and purification of CEA N-A1 domains we evaluated bacteria cultivation conditions, the length of N-A1 domains, fusion systems (GST- and MBP-tag), IPTG concentrations and protein purification conditions. We have found that MBP-N-A1 fusion protein digested with TEV protease forms soluble aggregates composed of N-A1 domains and incompletely digested MBP-N-A1 fusion protein. Using 1.25 M guanidinium chloride (GdmCl) as a component of the elution buffer we were able to achieve an almost complete dissociation of the aggregates. The dissociation was monitored by circular dichroism and fluorescence measurements. The CD spectra and Ellman's assay suggest that the conformation of N-A1 domains and their disulphide bonds are correct.

HLA-A*0201-restricted CEA-derived peptide CAP1 is not a suitable target for T-cell-based immunotherapy

Carcinoembryonic antigen (CEA) is a potential target for antigen-specific immunotherapy, as it is frequently overexpressed in human carcinomas. Moreover, an epitope derived from CEA, designated CAP1 (YLSGANLNL), has been proposed as naturally processed and presented by tumors in the human leukocyte antigen (HLA)-A*0201 context. Our aim was to fully characterize and assess the clinical relevance of the HLA-A*0201-restricted cytotoxic T lymphocyte (CTL) response against CEA. Stable and potent artificial antigen presenting cells (AAPCs) were used to evaluate T-cell response against CEA. These cells efficiently activate CTLs against tumor-derived epitopes after transduction with the antigenic peptides or full-length proteins. We found that AAPCs genetically modified to express CAP1, the agonist peptide CAP1-6D, or the whole CEA protein were not able to activate CAP1-specific CTLs from HLA-A*0201+ healthy donors or patients with colorectal carcinoma, even after multiple stimulations. In addition, we showed that a CAP1-specific T-cell clone, obtained after multiple stimulations of T cells of a HLA-A*0201+ healthy donor in vitro with autologous antigen presenting cells, recognized CEA(-) HLA-A*0201+ tumors transduced with a minigene encoding CAP1 but failed to react against HLA-A*0201+ tumor cells expressing CEA. Finally, AAPCs expressing the whole CEA protein did not induce any specific CTL response against CEA+ HLA-A*0201+ tumor cells highlighting the potential difficulty of mounting an efficacious T-cell response against this autoantigen. Altogether, our data indicate that CAP1 is not efficiently processed and presented by CEA+ tumor cells, and therefore, is not an appropriate target for T-cell-based immunotherapy.

Mutations in VIPAR cause an arthrogryposis, renal dysfunction and cholestasis syndrome phenotype with defects in epithelial polarization

Arthrogryposis, renal dysfunction and cholestasis syndrome (ARC) is a multisystem disorder associated with abnormalities in polarized liver and kidney cells. Mutations in VPS33B account for most cases of ARC. We identified mutations in VIPAR (also called C14ORF133) in individuals with ARC without VPS33B defects. We show that VIPAR forms a functional complex with VPS33B that interacts with RAB11A. Knockdown of vipar in zebrafish resulted in biliary excretion and E-cadherin defects similar to those in individuals with ARC. Vipar- and Vps33b-deficient mouse inner medullary collecting duct (mIMDC-3) cells expressed membrane proteins abnormally and had structural and functional tight junction defects. Abnormal Ceacam5 expression was due to mis-sorting toward lysosomal degradation, but reduced E-cadherin levels were associated with transcriptional downregulation. The VPS33B-VIPAR complex thus has diverse functions in the pathways regulating apical-basolateral polarity in the liver and kidney.

Human pregnancy specific beta-1-glycoprotein 1 (PSG1) has a potential role in placental vascular morphogenesis

Previous studies suggest that human pregnancy specific beta-1-glycoproteins (PSGs) play immunomodulatory roles during pregnancy; however, other possible functions of PSGs have yet to be explored. We have observed that PSGs induce transforming growth factor beta 1 (TGFB1), which among its other diverse functions inhibits T-cell function and has proangiogenic properties. The present study investigates a potential role for PSG1, the most abundant PSG in maternal serum, as a possible inducer of proangiogenic growth factors known to play an important role in establishment of the vasculature at the maternal-fetal interface. To this end, we measured TGFB1, vascular endothelial growth factors (VEGFs) A and C, and placental growth factor (PGF) protein levels in several cell types after PSG1 treatment. In addition, tube formation and wound healing assays were performed to investigate a possible direct interaction between PSG1 and endothelial cells. PSG1 induced up-regulation of both TGFB1 and VEGFA in human monocytes, macrophages, and two human extravillous trophoblast cell lines. We did not observe induction of VEGFC or PGF by PSG1 in any of the cells tested. PSG1 treatment resulted in endothelial tube formation in the presence and absence of VEGFA. Site-directed mutagenesis was performed to map the essential regions within the N-domain of PSG1 required for functional activity. We found that the aspartic acid at position 95, previously believed to be required for binding of PSGs to cells, is not required for PSG1 activity but that the amino acids implicated in the formation of a salt bridge within the N-domain are essential for PSG1 function.

Murine pregnancy-specific glycoprotein 23 induces the proangiogenic factors transforming-growth factor beta 1 and vascular endothelial growth factor a in cell types involved in vascular remodeling in pregnancy

Haemochorial placentation is a unique physiological process in which the fetal trophoblast cells remodel the maternal decidual spiral arteries to establish the fetoplacental blood supply. Pregnancy-specific glycoproteins (PSGs) are members of the carcinoembryonic antigen family. PSGs are produced by the placenta of rodents and primates and are secreted into the bloodstream. PSG23 is one of 17 members of the murine PSG family (designated PSG16 to PSG32). Previous studies determined that PSGs have immunoregulatory functions due to their ability to modulate macrophage cytokine secretion. Here we show that recombinant PSG23 induces transforming growth factor (TGF) beta1, TGFB1, and vascular endothelial growth factor A (VEGFA) in primary murine macrophages and the macrophage cell line RAW 264.7 cells. In addition, we identified new cell types that responded to PSG23 treatment. Dendritic cells, endothelial cells, and trophoblasts, which are involved in maternal vasculature remodeling during pregnancy, secreted TGFB1 and VEGFA in response to PSG23. PSG23 showed cross-reactivity with human cells, including human monocytes and the trophoblast cell line, HTR-8/SVneo cells. We analyzed the binding of PSG23 to the tetraspanin CD9, the receptor for PSG17, and found that CD9 is not essential for PSG23 binding and activity in macrophages. Overall these studies show that PSGs can modulate the secretion of important proangiogenic factors, TGFB1 and VEGFA, by different cell types involved in the development of the placenta.