Interleukin 1 and interleukin 1beta converting enzyme (caspase 1) expression in the human colonic epithelial barrier. Caspase 1 downregulation in colon cancer

Pathogenic diversification of the gut commensal Providencia alcalifaciens via acquisition of a second type III secretion system

Providencia alcalifaciens is a Gram-negative bacterium found in various water and land environments and organisms, including insects and mammals. Some P. alcalifaciens strains encode gene homologs of virulence factors found in pathogenic Enterobacterales members, such as Salmonella enterica serovar Typhimurium and Shigella flexneri. Whether these genes are pathogenic determinants in P. alcalifaciens is not known. In this study, we investigated P. alcalifaciens-host interactions at the cellular level, focusing on the role of two type III secretion systems (T3SS) belonging to the Inv-Mxi/Spa family. T3SS1b is widespread in Providencia spp. and encoded on the chromosome. A large plasmid that is present in a subset of P. alcalifaciens strains, primarily isolated from diarrheal patients, encodes for T3SS1a. We show that P. alcalifaciens 205/92 is internalized into eukaryotic cells, lyses its internalization vacuole, and proliferates in the cytosol. This triggers caspase-4-dependent inflammasome responses in gut epithelial cells. The requirement for the T3SS1a in entry, vacuole lysis, and cytosolic proliferation is host cell type-specific, playing a more prominent role in intestinal epithelial cells than in macrophages or insect cells. In a bovine ligated intestinal loop model, P. alcalifaciens colonizes the intestinal mucosa and induces mild epithelial damage with negligible fluid accumulation in a T3SS1a- and T3SS1b-independent manner. However, T3SS1b was required for the rapid killing of Drosophila melanogaster. We propose that the acquisition of two T3SS has allowed P. alcalifaciens to diversify its host range, from a highly virulent pathogen of insects to an opportunistic gastrointestinal pathogen of animals.

Inherently Reduced Expression of ASC Restricts Caspase-1 Processing in Hepatocytes and Promotes Plasmodium Infection

Inflammasome-mediated caspase-1 activation facilitates innate immune control of Plasmodium in the liver, thereby limiting the incidence and severity of clinical malaria. However, caspase-1 processing occurs incompletely in both mouse and human hepatocytes and precludes the generation of mature IL-1β or IL-18, unlike in other cells. Why this is so or how it impacts Plasmodium control in the liver has remained unknown. We show that an inherently reduced expression of the inflammasome adaptor molecule apoptosis-associated specklike protein containing CARD (ASC) is responsible for the incomplete proteolytic processing of caspase-1 in murine hepatocytes. Transgenically enhancing ASC expression in hepatocytes enabled complete caspase-1 processing, enhanced pyroptotic cell death, maturation of the proinflammatory cytokines IL-1β and IL-18 that was otherwise absent, and better overall control of Plasmodium infection in the liver of mice. This, however, impeded the protection offered by live attenuated antimalarial vaccination. Tempering ASC expression in mouse macrophages, on the other hand, resulted in incomplete processing of caspase-1. Our work shows how caspase-1 activation and function in host cells are fundamentally defined by ASC expression and offers a potential new pathway to create better disease and vaccination outcomes by modifying the latter.

Exploring the role of the inflammasomes on prostate cancer: Interplay with obesity

Obesity is a weight-related disorder characterized by excessive adipose tissue growth and dysfunction which leads to the onset of a systemic chronic low-grade inflammatory state. Likewise, inflammation is considered a classic cancer hallmark affecting several steps of carcinogenesis and tumor progression. In this regard, novel molecular complexes termed inflammasomes have been identified which are able to react to a wide spectrum of insults, impacting several metabolic-related disorders, but their contribution to cancer biology remains unclear. In this context, prostate cancer (PCa) has a markedly inflammatory component, and patients frequently are elderly individuals who exhibit weight-related disorders, being obesity the most prevalent condition. Therefore, inflammation, and specifically, inflammasome complexes, could be crucial players in the interplay between PCa and metabolic disorders. In this review, we will: 1) discuss the potential role of each inflammasome component (sensor, molecular adaptor, and targets) in PCa pathophysiology, placing special emphasis on IL-1β/NF-kB pathway and ROS and hypoxia influence; 2) explore the association between inflammasomes and obesity, and how these molecular complexes could act as the cornerstone between the obesity and PCa; and, 3) compile current clinical trials regarding inflammasome targeting, providing some insights about their potential use in the clinical practice.

AIM2 sensors mediate immunity to Plasmodium infection in hepatocytes

Malaria, caused by Plasmodium parasites is a severe disease affecting millions of people around the world. Plasmodium undergoes obligatory development and replication in the hepatocytes, before initiating the life-threatening blood-stage of malaria. Although the natural immune responses impeding Plasmodium infection and development in the liver are key to controlling clinical malaria and transmission, those remain relatively unknown. Here we demonstrate that the DNA of Plasmodium parasites is sensed by cytosolic AIM2 (absent in melanoma 2) receptors in the infected hepatocytes, resulting in Caspase-1 activation. Remarkably, Caspase-1 was observed to undergo unconventional proteolytic processing in hepatocytes, resulting in the activation of the membrane pore-forming protein, Gasdermin D, but not inflammasome-associated proinflammatory cytokines. Nevertheless, this resulted in the elimination of Plasmodium-infected hepatocytes and the control of malaria infection in the liver. Our study uncovers a pathway of natural immunity critical for the control of malaria in the liver.

The Influence of Bifidobacterium bifidum and Bacteroides fragilis on Enteric Glial Cell-Derived Neurotrophic Factors and Inflammasome

Enteric glial cells (EGCs) and enteric glial-derived neurotrophic factor (GDNF) are directly involved in intestinal inflammation. In this study, we sought to examine the possible mechanisms for how Bifidobacterium bifidum (B.b.) and Bacteroides fragilis (B.f.) influence EGC regulation. In this study, lipopolysaccharide (LPS) and interferon-γ (IFN-γ) were used as exogenous stimuli of EGCs to establish an intestinal inflammation model. After stimulation with LPS and IFN-γ, B.b. and B.f. supernatants were used to activate EGCs and to examine EGC immune mechanisms. For this purpose, qRT-PCR, western blotting, and laser scanning confocal microscopy (LSCM) were used to detect the expression of NLRP3, NLRP6, NGF, NT-3, IL-18, IL-1β, and caspase-1. We found that EGCs, after stimulation with LPS and IFN-γ, could express NLRP3, NLRP6, NT-3, NGF, IL-18, IL-1β, and caspase-1 through LSCM. In intestinal inflammation, B.b. and B.f. could trigger an increase in NGF and NT-3 expression in EGCs in order to protect the intestine. Furthermore, B.b. and B.f. could upregulate NLRP3 expression in EGCs and promote an inflammatory response. B.b. had a dual regulatory role in EGC NLRP6 expression, while B.f. inhibited NLRP6 protein expression. Moreover, B.b. could decrease the expression of IL-18, IL-1β, and caspase-1 in EGCs in order to inhibit the inflammatory response. Contrary to this, B.f. could upregulate IL-18, IL-1β, and caspase-1 expression in EGCs in order to promote the inflammatory response. B.b. and B.f. can influence the expression of NGF, NT-3, NLRP3, NLRP6, IL-18, IL-1β, and caspase-1 in EGCs in order to inhibit or promote intestinal inflammation.

The Caspase-1/IL-18 Axis of the Inflammasome in Tumor Cells: A Modulator of the Th1/Tc1 Response of Tumor-Infiltrating T Lymphocytes in Colorectal Cancer

In colorectal cancer (CRC), a high density of T lymphocytes represents a strong prognostic marker in subtypes of CRC. Optimized immunotherapy strategies to boost this T-cell response are still needed. A good candidate is the inflammasome pathway, an emerging player in cancer immunology that bridges innate and adaptive immunity. Its effector protein caspase-1 matures IL-18 that can promote a T-helper/cytotoxic (Th1/Tc1) response. It is still unknown whether tumor cells from CRC possess a functional caspase-1/IL-18 axis that could modulate the Th1/Tc1 response. We used two independent cohorts of CRC patients to assess IL-18 and caspase-1 expression by tumor cells in relation to the density of TILs and the microsatellite status of CRC. Functional and multiparametric approaches at the protein and mRNA levels were performed on an ex vivo CRC explant culture model. We show that, in the majority of CRCs, tumor cells display an activated and functional caspase-1/IL-18 axis that contributes to drive a Th1/Tc1 response elicited by TILs expressing IL-18Rα. Furthermore, unsupervised clustering identified three clusters of CRCs according to the caspase-1/IL-18/TIL density/interferon gamma (IFNγ) axis and microsatellite status. Together, our results strongly suggest that targeting the caspase-1/IL-18 axis can improve the anti-tumor immune response in subgroups of CRC.

IL-1 Signaling in Tumor Microenvironment

Interleukin 1 (IL-1) has long been known for its pleiotropic effects on inflammation that plays a complex, and sometimes contrasting, role in different stages of cancer development. As a major proinflammatory cytokine, IL-1β is mainly expressed by innate immune cells. IL-1α, however, is expressed by various cell types under physiological and pathological conditions. IL-1R1 is the main receptor for both ligands and is expressed by various cell types, including innate and adaptive immune cell types, epithelial cells, endothelial cells, adipocytes, chondrocytes, fibroblasts, etc. IL-1 and IL-1R1 receptor interaction leads to a set of common signaling pathways, mainly the NF-kB and MAP kinase pathways, as a result of complex positive and negative regulations. The variety of cell types with IL-1R1 expression dictates the role of IL-1 signaling at different stages of cancer, which under certain circumstances leads to contrasting roles in tumor development. Recent availability of IL-1R1 conditional knockout mouse model has made it possible to dissect the role of IL-1/IL-1R1 signaling transduction in different cell types within the tumor microenvironment. This chapter will focus on the role of IL-1/IL-1R1 in different cell types within the tumor microenvironment and discuss the potential of targeting this pathway in cancer therapy.

Plant protein diet suppressed immune function by inhibiting spiral valve intestinal mucosal barrier integrity, anti-oxidation, apoptosis, autophagy and proliferation responses in amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to investigate the effects of replacing dietary fishmeal with a plant protein blend on the growth performance, mucosal barrier integrity and the related regulation mechanism in Amur Sturgeon (Acipenser schrenckii) with initial weight of 87.48 g. Three isonitrogenous and isoenergetic diets were prepared. A basal diet containing 540 g/kg fishmeal (P0), whereas the other two diets were formulated by replacing 50% and 100% of FM with plant protein blend (soybean protein concentrate and cottonseed protein concentrate), and named as P50 and P100, respectively. Although essential amino acids, fatty acids, and available phosphorus had been balanced according to the nutrient requirement of sturgeon, compared with the fish of P0 and P50, the full plant protein diet (P100) significantly reduced growth performance and survival, and accompanied with serious spiral valve intestinal (SVI) damage. The increased tissue necrosis and failed responses in anti-oxidation, programming apoptosis, autophagy and cell proliferation system were regulated by inhibiting ERK1 phosphorylation, which indicated that SVI hypoimmunity and functional degradation were the main reasons for the high mortality and low utilization ability of plant protein in Amur sturgeon.

Fecal metatranscriptomics of macaques with idiopathic chronic diarrhea reveals altered mucin degradation and fucose utilization

BACKGROUND

Idiopathic chronic diarrhea (ICD) is a common cause of morbidity and mortality among juvenile rhesus macaques. Characterized by chronic inflammation of the colon and repeated bouts of diarrhea, ICD is largely unresponsive to medical interventions, including corticosteroid, antiparasitic, and antibiotic treatments. Although ICD is accompanied by large disruptions in the composition of the commensal gut microbiome, no single pathogen has been concretely identified as responsible for the onset and continuation of the disease.

RESULTS

Fecal samples were collected from 12 ICD-diagnosed macaques and 12 age- and sex-matched controls. RNA was extracted for metatranscriptomic analysis of organisms and functional annotations associated with the gut microbiome. Bacterial, fungal, archaeal, protozoan, and macaque (host) transcripts were simultaneously assessed. ICD-afflicted animals were characterized by increased expression of host-derived genes involved in inflammation and increased transcripts from bacterial pathogens such as Campylobacter and Helicobacter and the protozoan Trichomonas. Transcripts associated with known mucin-degrading organisms and mucin-degrading enzymes were elevated in the fecal microbiomes of ICD-afflicted animals. Assessment of colon sections using immunohistochemistry and of the host transcriptome suggests differential fucosylation of mucins between control and ICD-afflicted animals. Interrogation of the metatranscriptome for fucose utilization genes reveals possible mechanisms by which opportunists persist in ICD. Bacteroides sp. potentially cross-fed fucose to Haemophilus whereas Campylobacter expressed a mucosa-associated transcriptome with increased expression of adherence genes.

CONCLUSIONS

The simultaneous profiling of bacterial, fungal, archaeal, protozoan, and macaque transcripts from stool samples reveals that ICD of rhesus macaques is associated with increased gene expression by pathogens, increased mucin degradation, and altered fucose utilization. The data suggest that the ICD-afflicted host produces fucosylated mucins that are leveraged by potentially pathogenic microbes as a carbon source or as adhesion sites.

Cytochrome P450 1B1 inhibition suppresses tumorigenicity of prostate cancer via caspase-1 activation

Cytochrome P450 1B1 (CYP1B1) is recognized as a universal tumor biomarker and a feasible therapeutic target due to its specific overexpression in cancer tissues. Despite its up-regulation in prostate cancer (PCa), biological significance and clinicopathological features of CYP1B1 are still elusive. Here, we show that overexpression or hyperactivation of CYP1B1 stimulated proliferative, migratory and invasive potential of non-tumorigenic PCa cells. Attenuation of CYP1B1 with its specific small hairpin (sh) RNAs greatly reduced proliferation through apoptotic cell death and impaired migration and invasion in PCa cells. Intratumoral injection of CYP1B1 shRNA attenuated growth of pre-existing tumors. The antitumor effect of CYP1B1 shRNA was also observed in prostate tumor xenograft mouse models. Among the genes altered by CYP1B1 knockdown, reduction of caspase-1 (CASP1) activity attenuated the antitumor effect of CYP1B1 inhibition. Indeed, CYP1B1 regulates CASP1 expression or activity. Finally, CYP1B1 expression was increased in higher grades of PCa and overall survival was significantly reduced in patients with high levels of CYP1B1 protein. CYP1B1 expression was reversely associated with CASP1 expression in clinical tissue samples. Together, our results demonstrate that CYP1B1 regulates PCa tumorigenesis by inhibiting CASP1 activation. Thus, the CYP1B1-CASP1 axis may be useful as a potential biomarker and a therapeutic target for PCa.

Macrophage-derived interleukin-1beta promotes human breast cancer cell migration and lymphatic adhesion in vitro

Lymphovascular invasion (LVI), encompassing blood and lymphatic vessel invasion, is an important event in tumourigenesis. Macrophages within the tumour microenvironment are linked to the presence of LVI and angiogenesis. This study investigates the role of macrophage-derived, caspase-1-dependent interleukin-1beta (IL-1β) in an in vitro model of LVI. IL-1β significantly augmented the adhesion and transmigration of breast cancer cell lines MCF7 and MDA-MB-231 across endothelial cell barriers. MDA-MB-231 and MCF7 showed a higher percentage of adhesion to lymphatic endothelial cells than blood endothelial cells following endothelial cell IL-1β stimulation (P < 0.001 and P < 0.0001, respectively). Supernatants from activated macrophages increased the adhesion of tumour cells to lymphatic and blood endothelium. Secretion of IL-1β was caspase-1 dependent, and treatment with caspase-1 inhibitor reduced IL-1β production by 73% and concomitantly reduced tumour cell adhesion to levels obtained with resting macrophages. Transmigration of MDA-MB-231 cells across blood and lymphatic endothelial monolayers was significantly increased following IL-1β stimulation. Furthermore, supernatants from activated macrophages increased transmigration of MDA-MB-231 cells across endothelial monolayers, which was abolished by caspase-1 inhibition. IL-1β stimulation of tumour cells significantly increased their migratory ability and a significant increase in migration was observed when MDA-MB-231 cells were stimulated with macrophage conditioned media (two of three donors). Results demonstrate that macrophage production of IL-1β plays an important role in the migration of breast cancer cells and their adhesion to, and transmigration across, blood and lymphatic endothelial cells. Results suggest that IL-1β may play a role in the adhesion to lymphatic endothelial cells in particular.

Inflammasome expression and cytomegalovirus viremia in critically ill patients with sepsis

BACKGROUND

CMV viremia is a contributor to poor outcomes in critically ill patients with sepsis.

OBJECTIVES

To assess the expression levels of genes encoding inflammasome-related proteins in the development of CMV viremia in critically ill patients with sepsis.

STUDY DESIGN

A cohort of CMV-seropositive critically ill patients with sepsis due to bloodstream infection underwent weekly testing for CMV viremia. Blood samples to evaluate mRNA levels of genes encoding CASP1, ASC, NLRP1, NLRP3, and NLRP12 were collected at the time of enrollment. Clinical outcomes were assessed at 30days or until death/discharge from ICU.

RESULTS

CMV viremia was documented in 27.5% (8/29) of the patients, a median of 7days after the onset of bacteremia. Patients with sepsis who developed CMV viremia had higher CASP1 although this was not statistically significant (relative mean 3.6 vs 1.8, p=0.13). Development of high grade CMV viremia however, was significantly associated with CASP1; septic patients who developed high grade CMV viremia had significantly higher CASP1than all other patients (relative mean 5.5 vs 1.8, p=0.016).

CONCLUSIONS

These data document possible involvement of inflammasome in the pathogenesis of CMV. Regulating the host immune response by agents that target these genes may have implications for improving CMV-related outcomes in these patients.

Cytokine changes in gastric and colonic epithelial cell in response to Planta ovata extract

Background Psyllium (Planta ovata, Ispaghul) seed and husk are used for treatment of altered bowel habit, i. e. constipation and diarrhea. We studied the effect of Ispaghul extract on secretion of interleukin-1 beta (IL-1β) by AGS (ATCC CRL 1739) and SW480 (ATCC CCL-227) epithelial cell lines and determined whether Ispaghul extract has an effect on IL-1β secretion by Helicobacter pylori (H. pylori)-stimulated AGS cell and Escherichia coli K-12 (E. coli K-12)-stimulated SW480 cells in vitro. Methods The AGS cells and SW480 cells were pretreated with Ispaghul extract in concentrations, i. e. 3.5 and 7 μg/mL prior to infection with H. pylori and E. coli K-12. Results DNA fragmentation in AGS and SW480 cells treated with Ispaghul extract was not significant (2.3±0.8 %) compared with untreated cells (2.2±0.6 %). Ispaghul extract decreased the H. pylori-stimulated secretion of IL-1β by AGS cell (p<0.0001). This effect did not increase as the concentration of extract was increased. Ispaghul extract also decreased E. coli K-12-stimulated IL-1β secretion by SW480 cell (p<0.0001). This effect increased as the concentration of extracts was increased. Conclusions Ispaghul extract had an effect on stimulated secretion of IL-1β by the AGS and SW480 cell. It decreased pro-inflammatory reaction from both cell lines stimulated by bacteria.

Regulation of antiapoptotic and cytoprotective pathways in colonic epithelial cells in ulcerative colitis

Ulcerative colitis is an inflammatory bowel disease involving the colon resulting in bloody diarrhea and increased risk of colorectal cancer in certain patient subgroups. Increased apoptosis in the epithelial cell layer causes increased permeability, especially during flares; this leads to translocation of luminal pathogens resulting in a continued inflammatory drive. The present work investigates how epithelial apoptosis is regulated in ulcerative colitis. The main results are that Fas mediated apoptosis is inhibited during flares of ulcerative colitis, probably by an upregulation of cellular inhibitor of apoptosis protein 2 (cIAP2) and cellular FLICE-like inhibitory protein. cIAP2 is upregulated in regenerative epithelial cells both in ulcerative colitis and in experimental intestinal wounds. Inhibition of cIAP2 decreases wound healing in vitro possibly through inhibition of migration. Altogether, it is shown that epithelial cells in ulcerative colitis responds to the hostile microenvironment by activation of cytoprotective pathways that tend to counteract the cytotoxic effects of inflammation. However, the present studies also show that epithelial cells produce increased amounts of reactive oxygen species during stimulation with tumor necrosis factor-α and interferon-γ resulting in DNA instability. The combined effect of increased DNA-instability and decreased apoptosis responses could lead to neoplasia.

Heterogeneity of subordination of the IL-18/IFN-γ axis to caspase-1 among patients with Crohn's disease

In Crohn's disease (CD), hierarchical architecture of the inflammatory network, including subordination of IL-18, an IFN-γ-inducing cytokine, to the inflammasome, have remained undeciphered. Heterogeneity among patients of such a subordination cannot be evaluated by animal models, monofactorial in their etiology and homogenous in disease progression. To address these issues, we set up an ex vivo model of inflamed mucosa explant cultures from patients with active long-standing CD. Th1 cytokine production, especially IFN-γ and IL-18, was assessed in relation with inflammation intensity. Subordination of the Th1 response to caspase-1, effector of the inflammasome, was determined in explant cultures subjected to pharmacological inhibition of caspase-1 by YVAD. We showed a correlation between secreted IFN-γ/IL-18 levels, and caspase-1 activation, with inflammation intensity of intestinal CD mucosa explants. Inhibition of caspase-1 activation using the specific inhibitor YVAD identified a homogenous non responder group featuring a caspase-1-independent IL-18/IFN-γ response, and a heterogenous responder group, in which both IL-18 and IFN-γ responses were caspase-1-dependent, with a 40-70% range of inhibition by YVAD. These findings bring out the concept of heterogeneity of subordination of the Th1 response to inflammasome activation among CD patients. This ex vivo model should have therapeutic relevance in allowing to determine eligibility of CD patients for new targeted therapies.

Subversion of human intestinal mucosa innate immunity by a Crohn's disease-associated E. coli

Adherent-invasive Escherichia coli (AIEC), associated with Crohn's disease, are likely candidate contributory factors in the disease. However, signaling pathways involved in human intestinal mucosa innate host response to AIEC remain unknown. Here we use a 3D model of human intestinal mucosa explant culture to explore the effects of the AIEC strain LF82 on two innate immunity platforms, i.e., the inflammasome through evaluation of caspase-1 status, and NFκB signaling. We showed that LF82 bacteria enter and survive within a few intestinal epithelial cells and macrophages, without altering the mucosa overall architecture. Although 4-h infection with a Salmonella strain caused crypt disorganization, caspase-1 activation, and mature IL-18 production, LF82 bacteria were unable to activate caspase-1 and induce IL-18 production. In parallel, LF82 bacteria activated NFκB signaling in epithelial cells through IκBα phosphorylation, NFκBp65 nuclear translocation, and TNFα secretion. In addition, NFκB activation was crucial for the maintenance of epithelial homeostasis upon LF82 infection. In conclusion, here we decipher at the whole-mucosa level the mechanisms of the LF82-induced subversion of innate immunity that, by maintaining host cell integrity, ensure intracellular bacteria survival.

Naringin inhibits growth and induces apoptosis by a mechanism dependent on reduced activation of NF‑κB/COX‑2‑caspase-1 pathway in HeLa cervical cancer cells

Naringin (NRG), a bioflavonoid found in citrus fruit extracts, has been pharmacologically evaluated as a potential anticancer agent. This study confirmed a novel mechanism of the anticancer effects of NRG in the human cervical cancer HeLa cell line (HeLa cells). Exposure of HeLa cells to NRG resulted in growth inhibition, as evidenced by a decrease in cell viability. In addition, NRG treatment induced apoptosis, as indicated by the increased apoptotic percentage and the cleaved caspase-3 expression. Importantly, exposure of the cells to NRG attenuated the expression levels of phosphorylated (p) nuclear factor κB (NF-κB) p65 subunit, cyclooxygenase-2 (COX-2) and cysteinyl aspartate proteinase-1 (caspase-1). Treatment with PDTC (an inhibitor of NF-κB) or NS-398 (an inhibitor of COX-2) or SC-3069 (an inhibitor of caspase-1) markedly induced growth inhibition and apoptosis. Treatment with PDTC or NS-398 also reduced caspase-1 expression. Interestingly, PDTC treatment blocked the expression of COX-2 and NS-398 reduced the p-NF-κB p65 expression. Taken together, this study provides novel evidence that NRG induces growth inhibition and apoptosis by inhibiting the NF-κB/COX-2-caspase-1 pathway and that a positive interaction between NF-κB and COX-2 pathway contributes to the growth and antiapoptotic effect in HeLa cells.

Loss of interleukin-10 or transforming growth factor β signaling in the human colon initiates a T-helper 1 response via distinct pathways

BACKGROUND & AIMS

Signaling via interleukin (IL)-10 or transforming growth factor (TGF)-β is disrupted in subpopulations of patients with inflammatory bowel disease, but it is not clear how a T-helper (Th) 1 cell response is induced. We studied conversion of human mucosal innate immune cells into inflammatory cells and the initiation of a Th1 cell response following loss of IL-10 or TGF-β signaling.

METHODS

We depleted IL-10 or TGF-β from explant cultures of human normal colonic mucosa using immunoneutralization. Pharmacologic inhibitors and antibodies were used to determine the factors involved in the initiation of an interferon (IFN)-γ response following loss of TGF-β or IL-10 signaling. Cytokines produced by mucosal cells were assessed by enzyme-linked immunosorbent assay and quantitative reverse-transcriptase polymerase chain reaction. The subsets of cells involved in cytokine production were determined by in situ immunofluorescence analysis and flow cytometry after digestion of the explants with collagenase.

RESULTS

Depletion of IL-10 from human normal colonic mucosa resulted in an IFN-γ response, characterized by early-stage secretion of mature IL-18 and production of the active form of caspase-1 by macrophages and some epithelial cells. A caspase-1 inhibitor or the IL-18 antagonist IL-18-binding protein blocked this response. By contrast, depletion of TGF-β resulted in an IFN-γ response that was preceded by and required secretion of IL-12 from macrophages, dendritic cells, and epithelial cells.

CONCLUSIONS

Innate immune cells (macrophages and epithelial cells) activate a Th1 cell response in explant cultures of human normal colonic mucosa depleted in IL-10 or TGF-β via distinct, nonredundant pathways. These pathways might contribute to the pathogenesis of inflammatory bowel disease.

Prognostic impact of ΔTAp73 isoform levels and their target genes in colon cancer patients

PURPOSE

Cumulative data support the role of ΔTAp73 variants in tumorigenic processes such as drug resistance. We evaluate the impact of TP73 isoforms and their putative target genes ABCB1, HMGB1, and CASP1 on the survival of colon cancer patients and the correlation between their expressions.

EXPERIMENTAL DESIGN

We determined in 77 colon cancer patients the expression of ΔEx2p73, ΔEx2/3p73, ΔNp73, TAp73, ABCB1, HMGB1, and CASP1 by quantitative real-time reverse transcriptase-PCR. Tumor characteristics, disease-free survival, and overall survival (OS) were examined in each patient. Functional experiments were carried out to check whether ectopic expression of ΔNp73 modifies the proliferation, drug resistance, migration, and invasion properties of colon tumor cells and the expression of ABCB1, HMGB1, and CASP1.

RESULTS

Positive correlations were observed between the expression levels of ΔTAp73 variants and HMGB1. Furthermore, a trend was observed for ABCB1. Overexpression of ΔEx2/3p73 and ΔNp73 isoforms was significantly associated with advanced stages (P = 0.04 and P = 0.03, respectively) and predicted shortened OS (P = 0.04 and P = 0.05, respectively). High levels of ABCB1 and HMGB1 were associated with shorter OS (P = 0.04 and P = 0.05, respectively). Multivariate analysis showed that, in addition to the tumor stage, ABCB1 and HMGB1 had independent relationships with OS (P = 0.008). Ectopic expression of ΔNp73 was associated with an increase in proliferation and drug resistance.

CONCLUSIONS

The positive correlation between ΔTAp73 variants and HMGB1 and ABCB1 expression supports them as TP73 targets. The fact that upregulation of ΔTAp73 isoforms was associated with shortened OS, increase in proliferation, and drug resistance confirms their oncogenic role and plausible value as prognostic markers. ABCB1 and HMGB1, putative ΔTAp73 target genes, strongly predict OS in an independent manner, making clear the importance of studying downstream TP73 targets that could predict the outcome of colon cancer patients better than ΔTAp73 variants themselves do.

Inflammation-induced tumorigenesis in the colon is regulated by caspase-1 and NLRC4

Chronic inflammation is a known risk factor for tumorigenesis, yet the precise mechanism of this association is currently unknown. The inflammasome, a multiprotein complex formed by NOD-like receptor (NLR) family members, has recently been shown to orchestrate multiple innate and adaptive immune responses, yet its potential role in inflammation-induced cancer has been little studied. Using the azoxymethane and dextran sodium sulfate colitis-associated colorectal cancer model, we show that caspase-1-deficient (Casp1(-/-)) mice have enhanced tumor formation. Surprisingly, the role of caspase-1 in tumorigenesis was not through regulation of colonic inflammation, but rather through regulation of colonic epithelial cell proliferation and apoptosis. Consequently, caspase-1-deficient mice demonstrate increased colonic epithelial cell proliferation in early stages of injury-induced tumor formation and reduced apoptosis in advanced tumors. We suggest a model in which the NLRC4 inflammasome is central to colonic inflammation-induced tumor formation through regulation of epithelial cell response to injury.

Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae)

BACKGROUND

The delta smelt (Hypomesus transpacificus) is a pelagic fish species listed as endangered under both the USA Federal and Californian State Endangered Species Acts and considered an indicator of ecosystem health in its habitat range, which is limited to the Sacramento-San Joaquin estuary in California, USA. Anthropogenic contaminants are one of multiple stressors affecting this system, and among them, current-use insecticides are of major concern. Interrogative tools are required to successfully monitor effects of contaminants on the delta smelt, and to research potential causes of population decline in this species. We have created a microarray to investigate genome-wide effects of potentially causative stressors, and applied this tool to assess effects of the pyrethroid insecticide esfenvalerate on larval delta smelt. Selected genes were further investigated as molecular biomarkers using quantitative PCR analyses.

RESULTS

Exposure to esfenvalerate affected swimming behavior of larval delta smelt at concentrations as low as 0.0625 mug.L-1, and significant differences in expression were measured in genes involved in neuromuscular activity. Alterations in the expression of genes associated with immune responses, along with apoptosis, redox, osmotic stress, detoxification, and growth and development appear to have been invoked by esfenvalerate exposure. Swimming impairment correlated significantly with expression of aspartoacylase (ASPA), an enzyme involved in brain cell function and associated with numerous human diseases. Selected genes were investigated for their use as molecular biomarkers, and strong links were determined between measured downregulation in ASPA and observed behavioral responses in fish exposed to environmentally relevant pyrethroid concentrations.

CONCLUSIONS

The results of this study show that microarray technology is a useful approach in screening for, and generation of molecular biomarkers in endangered, non-model organisms, identifying specific genes that can be directly linked with sublethal toxicological endpoints; such as changes in expression levels of neuromuscular genes resulting in measurable swimming impairments. The developed microarrays were successfully applied on larval fish exposed to esfenvalerate, a known contaminant of the Sacramento-San Joaquin estuary, and has permitted the identification of specific biomarkers which could provide insight into the factors contributing to delta smelt population decline.

IL-33 is upregulated in colonocytes of ulcerative colitis

Interleukin-33 (IL-33) is a novel member of the IL-1 cytokine family. It has been shown to elicit a Th2-like cytokine response in immunocompetent cells through binding and activation of the T1/ST2 receptor. IL-33 has recently been associated with immune responses to helminthic intestinal infections, airway inflammation and arthritis in animal models. We now report IL-33 to be produced by colonic epithelial cells in humans and it is highly upregulated in ulcerative colitis (UC). Little mRNA expression was found in control subjects (N=9), whereas patients with UC in remission (N=7) and active UC (N=9) had a 3-fold (p<0.006) and 13-fold (p<0.0002) increased expression, respectively. On the protein level, IL-33 in its uncleaved form was overexpressed in active UC compared to controls (p<0.006) and inactive UC (p<0.03). Immunohistochemistry of IL-33 confirmed expression in active UC in colonic epithelial cells, whereas no detectable epithelial expression was seen in control specimens. Caspase 1, which is known to activate IL-33, was expressed in colonocytes, albeit at just detectable levels when the activated p20 caspase 1 was measured. Since IL-33 recently has been shown to be biologically active in its pro-form, and cleavage seems to inactivate IL-33, IL-33 is suggested to be active in UC. We found no IL-33 expression in Caco2 cells, regardless of stimulation by pro-inflammatory cytokines. In contrast to the IL-33 expression data, we could not show any difference in the production of another member of the IL-1 cytokine family, IL-1beta. This is the first study to describe that IL-33 is upregulated in UC. If IL-33 is driving a Th2-like cytokine response in UC, inhibition of the IL-33 T1/ST2 receptor pathway could be a future therapeutic option in UC.

Mucosal IL-10 and TGF-beta play crucial roles in preventing LPS-driven, IFN-gamma-mediated epithelial damage in human colon explants

IL-10 is an immunomodulatory cytokine that plays an obligate role in preventing spontaneous enterocolitis in mice. However, little is known about IL-10 function in the human intestinal mucosa. We showed here that IL-10 was constitutively expressed and secreted by the human normal colonic mucosa, including epithelial cells. Depletion of IL-10 in mucosal explants induced both downregulation of the IL-10-inducible, immunosuppressive gene BCL3 and upregulation of IFN-gamma, TNF-alpha, and IL-17. Interestingly, TGF-beta blockade also strongly induced IFN-gamma production. In addition, the high levels of IFN-gamma produced upon IL-10 depletion were responsible for surface epithelium damage and crypt loss, mainly by apoptosis. Polymyxin B, used as a scavenger of endogenous LPS, abolished both IFN-gamma production and epithelial barrier disruption. Finally, adding a commensal bacteria strain to mucosa explant cultures depleted of both IL-10 and LPS reproduced the ability of endogenous LPS to induce IFN-gamma secretion. These findings demonstrate that IL-10 ablation leads to an endogenous IFN-gamma-mediated inflammatory response via LPS from commensal bacteria in the human colonic mucosa. We also found that both IL-10 and TGF-beta play crucial roles in maintaining human colonic mucosa homeostasis.

From model cell line to in vivo gene expression: disease-related intestinal gene expression in IBD

Crohn's disease (CD) and ulcerative colitis (UC) are subforms of inflammatory bowel diseases (IBD). Genetic and environmental factors influencing the onset and course of the diseases have been recently identified. This study uses a two-step approach to detect genes involved in the pathogenesis of IBD by microarray analysis and real-time PCR (RT-PCR). In a first step, microarray expression screening was used to obtain tumour necrosis factor-alpha (TNF-alpha) induction profiles of two human cell lines to represent the tissue cell types involved in IBD. In a second step, a subset of differentially expressed genes was examined by real-time PCR in intestinal biopsy samples of normal controls (NC) compared with UC and CD patients, as well as to a cohort of patients suffering from intestinal diseases other than IBD. Data were obtained from 88 CD, 88 UC, 53 non-IBD patients (inflammatory control), DC and 45 NC individuals. The experimental design enabled the identification of disease-specific expressed genes. DnaJ (Hsp40) homologue, subfamily B, member 5 (DNAJB5) was downregulated in intestinal biopsy samples of the UC cohort compared with NC. A difference in JUNB expression levels was observed by comparing biopsy samples from inflamed and non-inflamed areas of UC patients. Transcript expression differences between IBD and control cohorts were found by examining histamine N-methyltransferase (HNMT), interleukin-1A (IL-1A) and proplatelet basic protein (PPBP) expression. The experimental procedure represents an approach to identify disease-relevant genes, which is applicable to any disease where appropriate model systems are available.

Gene expression profiles of primary colorectal carcinomas, liver metastases, and carcinomatoses

Background

Despite the fact that metastases are the leading cause of colorectal cancer deaths, little is known about the underlying molecular changes in these advanced disease stages. Few have studied the overall gene expression levels in metastases from colorectal carcinomas, and so far, none has investigated the peritoneal carcinomatoses by use of DNA microarrays. Therefore, the aim of the present study is to investigate and compare the gene expression patterns of primary carcinomas (n = 18), liver metastases (n = 4), and carcinomatoses (n = 4), relative to normal samples from the large bowel.

Results

Transcriptome profiles of colorectal cancer metastases independent of tumor site, as well as separate profiles associated with primary carcinomas, liver metastases, or peritoneal carcinomatoses, were assessed by use of Bayesian statistics. Gains of chromosome arm 5p are common in peritoneal carcinomatoses and several candidate genes (including PTGER4, SKP2, and ZNF622) mapping to this region were overexpressed in the tumors. Expression signatures stratified on TP53 mutation status were identified across all tumors regardless of stage. Furthermore, the gene expression levels for the in vivo tumors were compared with an in vitro model consisting of cell lines representing all three tumor stages established from one patient.

Conclusion

By statistical analysis of gene expression data from primary colorectal carcinomas, liver metastases, and carcinomatoses, we are able to identify genetic patterns associated with the different stages of tumorigenesis.

Tumour-associated angiogenesis in human colorectal cancer

Tumour angiogenesis is a critical step in the growth, metastatic spread and regrowth of colorectal cancer. Angiogenesis specific to tumour is a complicated process, the mechanisms of which remain unclear. Metastasis of colorectal cancer may result from passive entry into the circulation secondary to the effect of angiogenic factors. The survival and growth of colorectal tumour and thus their metastases are dependent on the balance of endogenous angiogenic and anti-angiogenic factors such that the outcome favours increased angiogenesis. Angiogenesis has become an attractive target for anticancer drug development, based on its important roles in tumour growth, invasion and metastasis. Several growth factors have been identified that regulate angiogenesis in colorectal cancer; the most important of these are vascular endothelial growth factors (VEGF), and of the several angiogenic factors, VEGF expression at the deepest invasive site of tumour is the most statistically significant prognostic indicator in advanced colorectal carcinoma. In this review article, we provide an overview on angiogenic factors and their receptors, and discuss the role of newly identified tumour endothelial markers (TEMs) that are involved in tumour-associated angiogenesis in colorectal cancer.

The expression of FHIT, PCNA and EGFR in benign and malignant breast lesions

Immunohistochemical staining for FHIT and PCNA proteins was carried out in 451 breast lesions showing nonproliferative benign breast disease (BBD) (n=263), proliferative BBD without atypia (n=128), proliferative BBD with atypia (n=11), carcinoma in situ (n=15) or invasive carcinoma (n=34) and for EGFR protein in a subset of 71 of these cases. FHIT underexpression was not detected in nonproliferative lesions, but occurred in 2% of proliferative BBD without atypia, 10% proliferative BBD with atypia, 27% of carcinoma in situ and 41% of invasive carcinoma, which suggests that it could be useful in assessing those carcinoma in situ lesions (ductal, DCIS and lobular, LCIS) that are more likely to progress to malignancy. Preliminary microarray comparisons on DCIS and invasive carcinoma samples dissected from formalin-fixed paraffin sections showed a consistent downregulation of two previously identified FHIT-related genes, caspase 1 and BRCA1 in lesions underexpressing FHIT.

IL-1beta alters hemodynamics in newborn intestine: role of endothelin

Studies were carried out to determine the effects of IL-1beta on newborn intestinal hemodynamics. IL-1beta increased the release of ET-1 by primary endothelial cells in a dose-dependent manner; as well, it reduced expression of the endothelin (ET) type B (ET(B)) receptor on endothelial cells and increased expression of the ET type A (ET(A)) receptor on vascular smooth muscle cells. IL-1beta increased endothelial cell endothelial nitric oxide (NO) synthase (eNOS) expression but did not enhance eNOS activity as evidenced by release of NO(x) into conditioned medium in response to acetylcholine or shear stress. The effects of IL-1beta on flow-induced dilation were evaluated in terminal mesenteric arteries in vitro. Pretreatment with IL-1beta (1 ng; 4 h) significantly attenuated vasodilation in response to flow rates of 100 and 200 microl/min. This effect was mediated, in part, by the endothelin ET(A) receptor; thus selective blockade of ET(A) receptors with BQ610 nearly restored flow-induced dilation. In contrast, exogenous ET-1 only shifted the diameter-flow curve downward without altering the percent vasodilation in response to flow. The effects of IL-1beta on ileal oxygenation were then studied using in vivo gut loops. Intramesenteric artery infusion of IL-1beta upstream of the gut loop caused ileal vasoconstriction and reduced the arterial-venous O(2) difference across the gut loop; consequently, it reduced ileal oxygenation by 60%. This effect was significantly attenuated by pretreatment with BQ610. These data support a linkage between the proinflammatory cytokine IL-1beta and vascular dysfunction within the intestinal circulation, mediated, at least in part, by the ET system.

Irinotecan changes gene expression in the small intestine of the rat with breast cancer

PURPOSE

The aetiology of mucositis is complex involving change in gene expression, altered apoptosis and interaction between epithelial and subepithelial compartments. This is the first investigation using microarray to assess chemotherapy-induced changes in the gut. The aims of this study were to identify genes that are altered by irinotecan, to determine how these genes contribute to apoptosis and to identify any potential gene families and pathways that are important for mucositis development.

METHODS

Tumour-bearing female dark Agouti rats were administered twice with 150 mg/kg of irinotecan and killed 6 h after the final dose. Jejunal tissue was harvested and RNA was isolated. cDNA was synthesised and purified, prior to hybridisation and microarray analysis. A 5-K oligo clone set was used to investigate gene expression. Results from the microarray were quantified using RT-PCR.

RESULTS

Many genes were significantly up- or down-regulated by irinotecan. In particular, multiple genes implicated in the mitogen-activated protein kinase (MAPK) signalling pathway were differentially regulated following treatment. These included interleukin 1 receptor, caspases, protein kinase C and dual-specificity phosphatase 6. RT-PCR was used to confirm effects of irinotecan on caspase-1 expression in jejunal tissue and was significantly increased 6 h after treatment with irinotecan.

CONCLUSIONS

This study has identified MAP kinase signalling as being involved with irinotecan-induced intestinal damage and confirms previous findings with radiation-induced oral mucosal damage, which also implicated this pathway. Microarrays are emerging as a valuable tool in mucositis research by linking such findings. The common pathway of chemotherapy- and radiotherapy-induced damage, which utilises the caspase-cascade, may be a useful target to prevent apoptosis following cancer treatment.

Colon cancer and apoptosis

BACKGROUND

The implementation of new therapeutic options for the management of metastatic colon cancer mandates a revisit to apoptosis and its role in colon cancer tumorigenesis with an emphasis on the mechanisms leading to chemotherapeutic resistance and immune system evasion of colon cancer cells.

DATA SOURCES

Literature regarding molecular apoptosis mechanisms and the role of apoptosis in colon cancer progression are reviewed by this article.

CONCLUSION

Programmed cell death has rapidly emerged as a potential target for cancer treatment at various stages of tumor progression. Chemoprevention, immuno-regulation, and metastasis are prospective targets by which apoptotic mechanisms could be utilized in the prevention and management of tumorigenesis. Understanding how defects in the death receptor pathway of apoptosis permit colon cancer cells to escape the immune system would allow for treatment options whereby the body's immune system could again recognize and eliminate unwanted cells.

Caspase activity is downregulated in choriocarcinoma: a cDNA array differential expression study

BACKGROUND

Placental trophoblast can be considered to be pseudomalignant tissue and the pathogenesis of gestational trophoblastic diseases remains to be clarified.

AIMS

To examine the role of caspases 8 and 10, identified by differential expression, on trophoblast tumorigenesis.

METHODS

cDNA array hybridisation was used to compare gene expression profiles in choriocarcinoma cell lines (JAR, JEG, and BeWo) and normal first trimester human placentas, followed by confirmation with quantitative real time polymerase chain reaction and immunohistochemistry. Caspase 10 and its closely related family member caspase 8 were analysed.

RESULTS

Downregulation of caspase 10 in choriocarcinoma was detected by both Atlastrade mark human cDNA expression array and Atlastrade mark human 1.2 array. Caspase 10 mRNA expression was significantly lower in hydatidiform mole (p = 0.035) and chorioarcinoma (p = 0.002) compared with normal placenta. The caspase 8 and 10 proteins were expressed predominantly in the cytotrophoblast and syncytiotrophoblast, respectively, with significantly lower expression in choriocarcinomas than other trophoblastic tissues (p < 0.05). Immunoreactivity for both caspase 8 and 10 correlated with the apoptotic index previously assessed by terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (p = 0.02 and p = 0.04, respectively) and M30 (p < 0.001 and p = 0.003, respectively) approaches.

CONCLUSIONS

These results suggest that the downregulation of capases 8 and 10 might contribute to the pathogenesis of choriocarcinoma.

Caspase-1α Is Down-regulated in Human Ovarian Cancer Cells and the Overexpression of Caspase-1α Induces Apoptosis

Caspase-1 plays a key role in the processing of cytokines and in the apoptosis of neurons and macrophages. Whether it also causes apoptosis of cancer cells has been unclear. In this study, we screened an array of apoptosis-related proteins in ovarian carcinoma cell lines and their tissue of origin, ovarian surface epithelium (OSE). Caspase-1alpha protein was abundant in OSE and in nontumorigenic OSE with extended but limited life spans (immortalized OSE), but was reduced in the cancer lines A2780 and OVCAR10. By Western blot and immunofluorescence, caspase-1alpha levels were greatly reduced in six of eight ovarian carcinoma lines compared with OSE. By real-time reverse transcription-PCR, steady-state transcripts of the CASP1 gene were proportional to protein levels. Caspase-1alpha overexpression caused significant apoptosis, but overexpression of a caspase-1alpha mutant without catalytic activity did not, confirming that the effect was caspase-1alpha-specific. Immunofluorescence of caspase-1alpha and terminal nucleotidyl transferase-mediated dUTP-X nick end labeling colocalization clearly established a link between apoptosis and caspase-1alpha expression. Caspase-9 and caspase-3 were activated in caspase-1alpha overexpressing A2780 cells, suggesting involvement of an intrinsic apoptotic pathway. Caspase-1alpha overexpression did not change the apoptotic effect of cisplatin in A2780 and OVCAR10 cells, suggesting that this agent activates a different pathway. Immunohistochemically, caspase-1 was lower in ovarian serous carcinomas than in OSE. Our study indicates, for the first time, that caspase-1alpha is proapoptotic in ovarian cancer cells, and raises the possibility that its down-regulation is one of the mechanisms which increase resistance to apoptosis in cancer cells.

Tumour endothelial marker 8 (TEM-8) in human colon cancer and its association with tumour progression

BACKGROUND AND AIMS

Tumour endothelial marker-8 (TEM-8) is endothelial cell surface marker that may be specific to tumour endothelial cells. This study examined the role of TEM-8 in human colon cancer and its correlation with tumour prognosis.

METHODOLOGY

Specimens of colorectal tissue (normal and cancer) were stained immunohistochemically with an anti-TEM-8 antibody, newly developed in our laboratory, and with anti-vonWillebrand Factor antibody. RNA was extracted from frozen sections for gene amplification. The anti-TEM-8 antibody specificity tested by using slot blotting with irrelevant antibody, and western blotting with different cell lines. The expression of TEM-8 was assessed using RT-PCR, and the level of TEM-8 was quantified using real-time-quantitative PCR (Q-RT-PCR).

RESULTS

TEM-8 staining was primarily seen in endothelial cells. TEM-8 identified more micro-vessels in colon tumour tissue, than in normal colon tissues, (p=0.002). Whereas, fewer vessels were stained positive for TEM-8 in normal tissues stained positive for vonWillebrand Factor (factor-8), (p=0.008). Malignant cells in tumour tissues were found to be stained strongly positive for TEM-8 compared with the epithelial cells in normal colon tissues. The level of TEM-8 expression was significantly higher in the tumour tissues compared to the normal colon mucosa (p=0.001). TEM-8 mRNA expression was also found to be more elevated in patients with advanced tumour, Dukes C (Dukes A vs. Dukes C, p=0.01).

CONCLUSION

TEM-8 is a marker that identifies tumour associated micro-vessels in colon cancer. The levels of expression of TEM-8 in invasive colon cancer are linked to disease progression. This suggests that TEM-8 has significant prognostic and therapeutic values in colon cancer.

Caspase-1zeta, a new splice variant of the caspase-1 gene

Five alternatively spliced mRNA isoforms of human caspase-1 have been identified previously and we report here the cloning of a new isoform, named CASP1 zeta (zeta), from human ovarian surface epithelial cell cDNA. The new isoform zeta is identical to the alpha isoform but missing 79 nucleotides in the coding region of the prodomain of procaspase-1. Analysis of the cDNA sequence of the zeta isoform revealed an ORF of a shorter protein missing the 39 amino acids at the amino terminal of procaspase-1alpha, which comprises the important caspase activating recruitment domain (CARD), which is required for interactions between caspases and other proteins. Secondary structure analysis of procaspase-1 CARD predicted the truncation of the alpha1, the alpha2, and part of the alpha3 helix in the zeta isoform in comparison to the full-length alpha isoform. The new zeta isoform was expressed in many, but not all, adult human tissues by RT-PCR. In HEK293 cells, transient overexpression of wild-type caspase-1zeta induced apoptosis to levels similar to those of caspase-1alpha. However, mutational change at the caspase-1 active center of the Cys 246 of caspase-1zeta, as well as Cys 285 of caspase-1alpha, completely abolished their apoptotic activity. Our findings suggest that caspase-1zeta is a widespread, new proapoptotic isoform of caspase-1. They also demonstrate that the first 39 amino acids of the N-terminal of the CARD in procaspase-1 are not required for its apoptotic activity.

Zerumbone, an anti-inflammatory phytochemical, induces expression of proinflammatory cytokine genes in human colon adenocarcinoma cell lines

Zerumbone, a sesquiterpene occurring in zingiberaceous plants in Southeast Asian countries, has been shown to have anti-inflammatory effects in several independent experimental studies. We examined its effect on the expression of proinflammatory genes in human colon adenocarcinoma cell lines, Caco-2, Colo320DM, and HT-29, using reverse transcription-polymerase chain reaction (RT-PCR) assays. Surprisingly, zerumbone markedly induced the expression of interleukin (IL)-1alpha, IL-1beta, IL-6, and tumor necrosis factor (TNF)-alpha in each cell line in concentration- and time-dependent manners. Results of a previous pharmacological approach using specific inhibitors of mitogen-activated protein kinases (MAPKs) suggested that the activation of both c-Jun N-terminal kinase and extracellular signal-regulated protein kinase, however, not that of p38 MAPK, may be involved in zerumbone-induced IL-1beta expression pathways in Caco-2 cells. The present results imply that zerumbone increases the production of proinflammatory cytokines in cancerous tissues in the colon and that this biochemical property may cause side-effects.

Human colon carcinomas constitutively express and shed type II IL-1 receptor, an IL-1 antagonist

We reported earlier that rat intestinal epithelial cells respond to helminth infection, to NSAID injury, and to detachment in vitro with expression of the IL-1RII. Now we have sought to determine whether human colon carcinoma cell lines express, or may be induced to express, this potent IL-1 antagonist. Using RT-PCR, the T84 and HT-29 cell lines constitutively expressed mRNA for the membrane-bound, but not the secreted variant of the receptor. The protein was detectable by immunohistochemistry and was estimated to be 70 kDa by western blotting. TNF treatment of T84 cells led to slightly increased levels of IL-1RII mRNA and to significant increases in soluble protein detected in culture supernatants. Treating T84 cells with inhibitory anti-IL-1RII antibodies led to heightened responsiveness to IL-1, measured as IL-8 production. Expression of the IL-1RII by human epithelial cells has implications in terms of the IL-1 agonist versus antagonist balance in the diseased intestines.

Differential expression and upregulation of interleukin-1alpha, interleukin-1beta and interleukin-6 by freshly isolated human small intestinal epithelial cells

BACKGROUND

Small intestinal epithelial cells (SIEC) may contribute to local immune regulation.

AIM

To examine production of interleukin (IL)-1alpha, IL-1beta and IL-6 by freshly isolated human SIEC.

METHODS

IL-1alpha and IL-1beta mRNA in epithelial layers (EL) prepared from small intestine and in intestinal epithelial cell (EC) lines were examined by reverse transcription-polymerase chain reaction. IL-1alpha, IL-1beta and IL-6 protein expression by SIEC was examined by flow cytometry before and after activation with lipopolysaccharide and epithelial growth factor.

RESULTS

IL-1alpha and IL-1beta mRNA was detected in EL and EC lines. Background expression of IL-1alpha and IL-1beta protein by SIEC was observed, which did not increase even following activation. IL-6 protein was expressed by SIEC, in a proportion that increased in two out of three samples following activation.

CONCLUSIONS

IL-6 expression and the presence of IL-1alpha and IL-1beta mRNA suggest a role for SIEC in the regulation of local inflammation.

Regulation of proinflammatory cytokines in human lung epithelial cells infected with Mycoplasma pneumoniae

Mycoplasma pneumoniae is a small bacterium without a cell wall that causes tracheobronchitis and atypical pneumonia in humans. It has also been associated with chronic conditions, such as arthritis, and extrapulmonary complications, such as encephalitis. Although the interaction of mycoplasmas with respiratory epithelial cells is a critical early phase of pathogenesis, little is known about the cascade of events initiated by infection of respiratory epithelial cells by mycoplasmas. Previous studies have shown that M. pneumoniae can induce proinflammatory cytokines in several different study systems including cultured murine and human monocytes. In this study, we demonstrate that M. pneumoniae infection also induces proinflammatory cytokine expression in A549 human lung carcinoma cells. Infection of A549 cells resulted in increased levels of interleukin-8 (IL-8) and tumor necrosis factor alpha mRNA, and both proteins were secreted into culture medium. IL-1 beta mRNA also increased after infection and IL-1 beta protein was synthesized, but it remained intracellular. In contrast, levels of IL-6 and gamma interferon mRNA and protein remained unchanged or undetectable. Using protease digestion and antibody blocking methods, we found that M. pneumoniae cytoadherence is important for the induction of cytokines. On the other hand, while M. pneumoniae protein synthesis and DNA synthesis do not appear to be prerequisites for the induction of cytokine gene expression, A549 cellular de novo protein synthesis is responsible for the increased cytokine protein levels. These results suggest a novel role for lung epithelial cells in the pathogenesis of M. pneumoniae infection and provide a better understanding of M. pneumoniae pathology at the cellular level.

Relationship of the interleukin-1 system with neuroendocrine and exocrine markers in human colon cancer cell lines

Interleukin 1 (IL-1) is known to regulate the proliferation and differentiation of normal and malignant immune cells as well as other cell types. Expression of IL-1 (alpha and beta), IL-1 receptors (RI and RII) and IL-1 receptor antagonist (IL-1RA) was determined by RT-PCR in seven human colon carcinoma cell lines (COLO 320DM, LoVo, SW403, SW1116, SW1417, LS123 and LS174t). Influence of IL-1 on the secretion of the neuroendocrine (NE) differentiation marker chromogranin A (CGA) and the exocrine marker carcinoembryonic antigen (CEA) was examined by Western blotting. Our data indicate that CGA and IL-1RI are expressed by all seven, IL-1 beta by five, IL-1RII and IL-1RA by six lines. IL-1 alpha transcripts were found only in three lines (LoVo, SW1116 and LS174t) and correlated with high CEA levels and aggressive growth behavior. "Pure" NE cell lines (COLO 320DM and LS123) secreted the highest levels of CGA, but the lowest levels of CEA and were IL-1 (alpha and beta) negative. Exogenously added IL-1 caused a decrease in CGA, but an increase in CEA secretion. Our results suggest an inverse relationship between IL-1 and NE differentiation, as well as a direct relationship between IL-1 and CEA expression in colon carcinoma.

Overexpression of the CD155 gene in human colorectal carcinoma

BACKGROUND AND AIMS

The Tage4 gene (tumour associated glycoprotein E4) is overexpressed in rat colon tumours and Min mouse intestinal adenomas. The rat Tage4 protein has approximately 40% identity with human CD155, a member of the immunoglobulin superfamily coding for a transmembrane protein capable of serving as an entry receptor for poliovirus, porcine pseudorabies virus, and bovine herpesvirus 1. Analysis of the rat Tage4 gene has revealed structural and functional similarities with the human CD155 gene. We therefore investigated expression of the CD155 gene in human colorectal carcinomas.

METHODS

Overall CD155 expression was assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical analysis using tissue specimens from patients with colorectal adenomas and adenocarcinomas. We also used a qualitative RT-PCR assay to determine relative expression of different splicing variants in each sample.

RESULTS

mRNA levels of CD155 were increased in six of six colorectal cancer tissues compared with the tumour free colon mucosa. Immunohistochemical analysis revealed an increased level of CD155 protein in 12 of 12 samples. The qualitative RT-PCR assay revealed that relative expression of the different CD155 variant transcripts was similar in the different normal and cancer samples tested, indicating that this overexpression is not associated with a particular mRNA variant generated by alternative splicing of the CD155 gene.

CONCLUSION

We have shown for the first time that the CD155 gene is overexpressed in colorectal carcinoma and that this overexpression begins at an early stage in tumorigenesis and continues to late stages.

Caspase 7 downregulation as an immunohistochemical marker of colonic carcinoma

Caspases play a crucial role as apoptotic effectors; their potential implication in tumorigenesis remains to be clarified. We investigated the expression and function of caspases 7, 8, and 9 in colon cancer tissues and cell lines. Immunohistochemistry (IHC) showed downregulation of caspase 7 (22 of 26 cases) and caspase 9 (12 of 26 cases) in colonic cancer samples compared with normal mucosa on the same tissue section. Caspase 8 expression was unchanged or slightly upregulated (19 of 27 cases). The combination of IHC and Western blot analysis showed expression of the proforms of caspases 7, 8, and 9 in HT29-19A and HT29-16E colonic carcinoma cell lines. Apoptosis could be induced by staurosporine in both HT29 cell lines, with a sensitivity similar to that of the HGT cell line, but lower than that of the DAUDI cell line. Apoptosis induction in HT29 cells was concomitant with processing of caspases 3, 7, 8, and 9 and was inhibited by the caspase inhibitor ZVAD. Our data show that (1) human colon cancer cells downregulate caspase 7 and, to a smaller extent, caspase 9 in vivo and (2) in vitro staurosporine-induced apoptosis of colonic cancer cells involves caspases 7 and 9. Caspase 7 deficiency thus appears as a new immunohistochemical marker of colonic neoplasia; its correction represents a potential basis for new therapies.

Immune privilege or inflammation? Insights into the Fas ligand enigma

Fas ligand (FasL) has become an enigmatic molecule: some evidence indicates that it contributes to immune privilege in tissues and tumors, whereas other data demonstrates that FasL can elicit inflammation. New findings may begin to reconcile the paradoxical effects of FasL.

Apoptosis (programmed cell death) in colonic cells: from normal to transformed stage

We determined apoptosis in whole rat colonic tissue and in isolated colonocytes from the various rat crypt regions in preneoplastic stages up to frank neoplasia following administration of the procarcinogen, dimethylhydrazine (DMH). Apoptotic cells were determined by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL)-method, by evaluating sections stained with hematoxylin and eosin, and caspase-1 immunostaining. Apoptotic cells in whole colonic tissue from untreated rats were confined to the upper crypt while, in DMH-treated rats apoptotic and caspase-1 positive cells were located in the crypt proliferative regions. Numerous apoptotic and caspase-1-positive cells were found in sections from early tumors while in the delayed tumors, apoptotic-positive cells were absent and number of caspase-1-positive cells was negligible. A marked reduction in the apoptotic index along the crypt was observed in isolated transformed colonic cells, this was not the case for caspase-1-positive cells. We conclude that: (i) in colorectal tumors at progressive stage apoptosis is altered, (ii) the mechanistic alteration in apoptosis may be located between caspase-1-protease activity and the fragmentation process of DNA.

Interferon-gamma sensitizes colonic epithelial cell lines to physiological and therapeutic inducers of colonocyte apoptosis

Homeostasis in the colonic epithelium is achieved by a continuous cycle of proliferation and apoptosis, in which imbalances are associated with disease. Inflammatory bowel disease (IBD) and colon cancer are associated with either excessive or insufficient apoptosis of colonic epithelial cells, respectively. By using two colonic epithelial cell lines, HT29 and SW620, we investigated how the epithelial cell's sensitivity to apoptosis was regulated by the proinflammatory cytokine interferon-gamma (IFN-gamma). We found that IFN-gamma sensitized HT29 cells, and to a lesser extent SW620, to diverse inducers of apoptosis of physiologic or therapeutic relevance to the colon. These apoptosis inducers included Fas (CD95/APO-1) ligand (FasL), short-chain fatty acids, and chemotherapeutic drugs. The extent of IFN-gamma-mediated apoptosis sensitization in these two cell lines correlated well with the degree of IFN-gamma-mediated upregulation of the proapoptotic protease caspase-1. Although IFN-gamma alone effectively sensitized HT29 cells to apoptosis, inclusion of the protein synthesis inhibitor cyclohexamide (CHX) during apoptotic challenge was necessary for maximal sensitization of SW620. The requirement of CHX to sensitize SW620 cells to apoptosis implies a need to inhibit translation of antiapoptotic proteins absent from HT29. In particular, the antiapoptotic protein Bcl-2 was strongly expressed in SW620 cells but absent from HT29. Our results indicate that IFN-gamma increases the sensitivity of colonic epithelial cells to diverse apoptotic stimuli in concert, via upregulation of caspase-1. Our findings implicate caspase-1 and Bcl-2 as important central points of control determining the general sensitivity of colonic epithelial cells to apoptosis.