Caveolin-1 protects B6129 mice against Helicobacter pylori gastritis

Caspase-11 contributes to site-1 protease cleavage and SREBP1 activation in the inflammatory response of macrophages

Sterol regulatory element-binding proteins (SREBPs) are key transcription factors that control fatty acid and cholesterol metabolism. As the major SREBP isoform in macrophages, SREBP1a is also required for inflammatory and phagocytotic functions. However, it is insufficiently understood how SREBP1a is activated by the innate immune response in macrophages. Here, we show that mouse caspase-11 is a novel inflammatory activator of SREBP1a in macrophages. Upon LPS treatment, caspase-11 was found to promote the processing of site-1 protease (S1P), an enzyme that mediates the cleavage and activation of SREBP1. We also determined that caspase-11 directly associates with S1P and cleaves it at a specific site. Furthermore, deletion of the Casp4 gene, which encodes caspase-11, impaired the activation of S1P and SREBP1 as well as altered the expression of genes regulated by SREBP1 in macrophages. These results demonstrate that the caspase-11/S1P pathway activates SREBP1 in response to LPS, thus regulating subsequent macrophage activation.

Functional antagonism between CagA and DLC1 in gastric cancer

Helicobacter (H.) pylori-induced gastritis is a risk factor for gastric cancer (GC). Deleted-in-liver-cancer-1 (DLC1/ARHGAP7) inhibits RHOA, a downstream mediator of virulence factor cytotoxin-A (CagA) signalling and driver of consensus-molecular-subtype-2 diffuse GC. DLC1 located to enterochromaffin-like and MIST1+ stem/chief cells in the stomach. DLC1+ cells were reduced in H. pylori gastritis and GC, and in mice infected with H. pylori. DLC1 positivity inversely correlated with tumour progression in patients. GC cells retained an N-terminal truncation variant DLC1v4 in contrast to full-length DLC1v1 in non-neoplastic tissues. H. pylori and CagA downregulated DLC1v1/4 promoter activities. DLC1v1/4 inhibited cell migration and counteracted CagA-driven stress phenotypes enforcing focal adhesion. CagA and DLC1 interacted via their N- and C-terminal domains, proposing that DLC1 protects against H. pylori by neutralising CagA. H. pylori-induced DLC1 loss is an early molecular event, which makes it a potential marker or target for subtype-aware cancer prevention or therapy.

The Role of Lipid Metabolism in Gastric Cancer

Gastric cancer has been one of the most common cancers worldwide with extensive metastasis and high mortality. Chemotherapy has been found as a main treatment for metastatic gastric cancer, whereas drug resistance limits the effectiveness of chemotherapy and leads to treatment failure. Chemotherapy resistance in gastric cancer has a complex and multifactorial mechanism, among which lipid metabolism plays a vital role. Increased synthesis of new lipids or uptake of exogenous lipids can facilitate the rapid growth of cancer cells and tumor formation. Lipids form the structural basis of biofilms while serving as signal molecules and energy sources. It is noteworthy that lipid metabolism is capable of inducing drug resistance in gastric cancer cells by reshaping the tumor micro-environment. In this study, new mechanisms of lipid metabolism in gastric cancer and the metabolic pathways correlated with chemotherapy resistance are reviewed. In particular, we discuss the effects of lipid metabolism on autophagy, biomarkers treatment and drug resistance in gastric cancer from the perspective of lipid metabolism. In brief, new insights can be gained into the development of promising therapies through an in-depth investigation of the mechanism of lipid metabolism reprogramming and resensitization to chemotherapy in gastric cancer cells, and scientific treatment can be provided by applying lipid-key enzyme inhibitors as cancer chemical sensitizers in clinical settings.

Caveolae as Potential Hijackable Gates in Cell Communication

Caveolae are membrane microdomains described in many cell types involved in endocytocis, transcytosis, cell signaling, mechanotransduction, and aging. They are found at the interface with the extracellular environment and are structured by caveolin and cavin proteins. Caveolae and caveolins mediate transduction of chemical messages via signaling pathways, as well as non-chemical messages, such as stretching or shear stress. Various pathogens or signals can hijack these gates, leading to infectious, oncogenic and even caveolin-related diseases named caveolinopathies. By contrast, preclinical and clinical research have fallen behind in their attempts to hijack caveolae and caveolins for therapeutic purposes. Caveolae involvement in human disease is not yet fully explored or understood and, of all their scaffold proteins, only caveolin-1 is being considered in clinical trials as a possible biomarker of disease. This review briefly summarizes current knowledge about caveolae cell signaling and raises the hypothesis whether these microdomains could serve as hijackable “gatekeepers” or “gateways” in cell communication. Furthermore, because cell signaling is one of the most dynamic domains in translating data from basic to clinical research, we pay special attention to translation of caveolae, caveolin, and cavin research into clinical practice.

Effect of β-caryophyllene from Cloves Extract on Helicobacter pylori Eradication in Mouse Model

New antibacterial treatments against Helicobacter pylori are needed as H. pylori is acquiring antibiotic resistance. β-caryophyllene is a natural bicyclic sesquiterpene, with anti-inflammatory and antimicrobial effects. This study investigates the effects of H-002119-00-001 from β-caryophyllene on the eradication of H. pylori in a mouse model, and its effects on the inflammation of the gastric mucosa. To evaluate the anti-H.pylori efficacy of β-caryophyllene, a total of 160 mice were divided into eight groups (n = 10 each) and were administered different treatments for 2 and 4 weeks. H. pylori eradication was assessed using a Campylobacter-like organism (CLO) test and H. pylori qPCR of the gastric mucosa. The levels of inflammation of gastric mucosa were assessed using histology and immunostaining. H-002119-00-001 decreased bacterial burden in vitro. When H-002119-00-001 was administered to mice once daily for 2 weeks, cure rates shown by the CLO test were 40.0%, 60.0%, and 70.0% in groups 6, 7, and 8, respectively. H. pylori levels in gastric mucosa decreased dose-dependently after H-002119-00-001 treatment. H-002119-00-001 also reduced levels of inflammation in gastric mucosa. H-002119-00-001 improved inflammation and decreased bacterial burden in H. pylori-infected mouse models. H-002119-00-001 is a promising and effective therapeutic agent for the treatment of H. pylori infection.

Cell Intrinsic and Extrinsic Mechanisms of Caveolin-1-Enhanced Metastasis

Caveolin-1 (CAV1) is a scaffolding protein with a controversial role in cancer. This review will initially discuss earlier studies focused on the role as a tumor suppressor before elaborating subsequently on those relating to function of the protein as a promoter of metastasis. Different mechanisms are summarized illustrating how CAV1 promotes such traits upon expression in cancer cells (intrinsic mechanisms). More recently, it has become apparent that CAV1 is also a secreted protein that can be included into exosomes where it plays a significant role in determining cargo composition. Thus, we will also discuss how CAV1 containing exosomes from metastatic cells promote malignant traits in more benign recipient cells (extrinsic mechanisms). This ability appears, at least in part, attributable to the transfer of specific cargos present due to CAV1 rather than the transfer of CAV1 itself. The evolution of how our perception of CAV1 function has changed since its discovery is summarized graphically in a time line figure.

Aryl hydrocarbon receptor nuclear translocator-like (ARNTL/BMAL1) is associated with bevacizumab resistance in colorectal cancer via regulation of vascular endothelial growth factor A

BACKGROUND

The identification of new biomarkers and the development of novel, targetable contexts of vulnerability are of urgent clinical need in drug-resistant metastatic colorectal cancer (mCRC). Aryl-Hydrocarbon-Receptor-Nuclear-Translocator-Like (ARNTL/BMAL1) is a circadian clock-regulated transcription factor promoting expression of genes involved in angiogenesis and tumour progression. We hypothesised that BMAL1 increases expression of the vascular endothelial growth factor A VEGFA gene and, thereby, confers resistance to anti-angiogenic therapy with bevacizumab (Beva), a clinically used antibody for neutralization of VEGFA.

METHODS

PCR and immunohistochemistry were employed to assess BMAL1 expression in mice (C57BL/6 J Apcmin/+; BALB/c nu/nu xenografts) and CRC patients under combination chemotherapy with Beva. BMAL1 single nucleotide gene polymorphisms (SNPs) were analysed by DNA-microarray in clinical samples. BMAL1 functions were studied in human CRC cell lines using colorimetric growth, DNA-binding and reporter assays.

FINDINGS

In murine CRCs, high BMAL1 expression correlated with poor preclinical response to Beva treatment. In CRC patients' tumours (n = 74), high BMAL1 expression was associated with clinical non-response to combination chemotherapy with Beva (*p = .0061) and reduced progression-free survival (PFS) [*p = .0223, Hazard Ratio (HR) = 1.69]. BMAL1 SNPs also correlated with shorter PFS (rs7396943, rs7938307, rs2279287) and overall survival (OS) [rs11022780, *p = .014, HR = 1.61]. Mechanistically, Nuclear-Receptor-Subfamily-1-Group-D-Member-1 (NR1D1/REVERBA) bound a - 672 bp Retinoic-Acid-Receptor-Related-Orphan-Receptor-Alpha-responsive-element (RORE) adjacent to a BMAL1 DNA-binding motif (E-box) in the VEGFA gene promoter, resulting in increased VEGFA synthesis and proliferation of human CRC cell lines.

INTERPRETATION

BMAL1 was associated with Beva resistance in CRC. Inhibition of REVERBA-BMAL1 signalling may prevent resistance to anti-angiogenic therapy. FUND: This work was in part supported by the European Commission Seventh Framework Programme (Contract No. 278981 [ANGIOPREDICT]).

Mechanisms of Inflammasome Signaling, microRNA Induction and Resolution of Inflammation by Helicobacter pylori

Inflammasome-controlled transcription and subsequent cleavage-mediated activation of mature IL-1β and IL-18 cytokines exemplify a crucial innate immune mechanism to combat intruding pathogens. Helicobacter pylori represents a predominant persistent infection in humans, affecting approximately half of the population worldwide, and is associated with the development of chronic gastritis, peptic ulcer disease, and gastric cancer. Studies in knockout mice have demonstrated that the pro-inflammatory cytokine IL-1β plays a central role in gastric tumorigenesis. Infection by H. pylori was recently reported to stimulate the inflammasome both in cells of the mouse and human immune systems. Using mouse models and in vitro cultured cell systems, the bacterial pathogenicity factors and molecular mechanisms of inflammasome activation have been analyzed. On the one hand, it appears that H. pylori-stimulated IL-1β production is triggered by engagement of the immune receptors TLR2 and NLRP3, and caspase-1. On the other hand, microRNA hsa-miR-223-3p is induced by the bacteria, which controls the expression of NLRP3. This regulating effect by H. pylori on microRNA expression was also described for more than 60 additionally identified microRNAs, indicating a prominent role for inflammatory and other responses. Besides TLR2, TLR9 becomes activated by H. pylori DNA and further TLR10 stimulated by the bacteria induce the secretion of IL-8 and TNF, respectively. Interestingly, TLR-dependent pathways can accelerate both pro- and anti-inflammatory responses during H. pylori infection. Balancing from a pro-inflammation to anti-inflammation phenotype results in a reduction in immune attack, allowing H. pylori to persistently colonize and to survive in the gastric niche. In this chapter, we will pinpoint the role of H. pylori in TLR- and NLRP3 inflammasome-dependent signaling together with the differential functions of pro- and anti-inflammatory cytokines. Moreover, the impact of microRNAs on H. pylori-host interaction will be discussed, and its role in resolution of infection versus chronic infection, as well as in gastric disease development.

Anti-inflammatory effects of Kaempferol on Helicobacter pylori-induced inflammation

Inflammation induced by Helicobacter pylori infection related to gastric carcinogenesis. In this study, we have investigated the anti-inflammatory effect and its mechanism of kaempferol in the inflammatory response caused by H. pylori infection in vitro. We found that kaempferol reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-8) and production of IL-8 in AGS cells. In addition, kaempferol suppressed translocation of cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) of H. pylori to AGS cells. It was due to decreased transcription of type IV secretion system (T4SS) components involved in CagA injection and secretion system subunit protein A (SecA) of type V secretion system (T5SS) involved in VacA secretion by kaempferol. In conclusion, kaempferol shows the anti-inflammatory effect by suppressing the translocation of CagA and VacA proteins and leading to the down-regulation of pro-inflammatory cytokines. Abbreviations: CagA: cytotoxin-associated gene A; VacA: vacuolating cytotoxin A; T4SS: type IV secretion systems; SecA: secretion system subunit protein A; T5SS: type V secretion system.

All-trans retinoic acid inhibits the proliferation of SGC7901 cells by regulating caveolin-1 localization via the ERK/MAPK signaling pathway

Caveolin-1 is a scaffold protein of caveolae in the mucosa of the gastrointestinal tract and acts as a tumor modulator by interacting with cell adhesion molecules and signaling receptors. Caveolin-1 stabilizes cell-cell and cell-matrix contacts and is a hallmark of a number of different types of human cancer, including gastric cancer. All-trans retinoic acid (ATRA), a derivative of vitamin A, has been demonstrated to exhibit tumor inhibitory effects in acute leukemia and certain types of solid tumor. In the present study, treatment with ATRA was demonstrated to inhibit the proliferation of gastric cancer cell line SGC7901, in a time- and dose-dependent manner. The markedly increased membrane localization of caveolin-1 was observed in the cells that were treated with 10 µmol/l ATRA for > 48 h. In addition, it was observed that treatment with ATRA was able to regulate the level of phosphorylation of extracellular signal-regulated kinase (ERK). Therefore, the SGC7901 cells were treated with a specific agonist of ERK/mitogen-activated protein kinase (MAPK) investigate whether ATRA mediated its effects via the ERK/MAPK signaling pathway. The results of the present study demonstrated that ATRA-induced increase in membrane localization of caveolin-1 was reversed by treatment with a specific agonist of ERK/MAPK. Together, these results suggest that ATRA exhibits anti-gastric cancer effects. ATRA may regulate the membrane localization of caveolin-1 in order to inhibit the proliferation of SGC7901 cells. These effects of ATRA may be mediated by inhibiting the activation of ERK/MAPK signaling pathway. These results contribute to the current knowledge on the potential use of ATRA as therapy for solid tumors and provide further insight into the potential molecular mechanisms of ATRA action.

Identification and characterization of molluscan caveolin-1 ortholog from Haliotis discus discus: Possible involvement in embryogenesis and host defense mechanism against pathogenic stress

Caveolins are principal membrane proteins of caveolae that play a central role in signal transduction, substrate transport, and membrane trafficking in various cell types. Numerous studies have reported the crucial role of caveolin-1 (CAV1) in response to invading microbes; yet, very little is known about molluscan CAV1. In this study, we identified and characterized CAV1 ortholog from the disk abalone, Haliotis discus discus (HdCAV1). The cDNA sequence of HdCAV1 is 826 bp long and encodes a 127-amino acid polypeptide. Characteristic caveolin superfamily domain (Glu³ - Lys¹²⁶) and two possible transmembrane domains (Cys⁴⁸ - Tyr⁶⁷ and Ile¹⁰³ - Phe¹²⁰) were identified in the HdCAV1 protein. Homology analysis revealed that HdCAV1 shared higher identity (>47%) with molluscans, but lower identity with other species. Phylogenetic tree constructed by the neighbor-joining (NJ) method revealed a distinct evolutionary pathway for molluscans. Transcriptional analysis by SYBR Green qPCR showed the highest expression of HdCAV1 mRNA in late veliger stage, as compared to that in other embryonic developmental stages of disk abalone. In adult animals, gill tissue showed highest HdCAV1 transcript levels under normal physiological condition. Stimulations with two bacteria (Vibrio parahaemolyticus and Listeria monocytogenes), viral hemorrhagic septicemia virus, and two pathogen-associated molecular patterns (LPS and poly I:C) significantly modulated the expression of HdCAV1 transcripts. Collectively, these data suggest that CAV1 plays an important role in embryogenesis and host immune defense in disk abalone.

An epigenome-wide association study of inflammatory response to fenofibrate in the Genetics of Lipid Lowering Drugs and Diet Network

AIM

Fenofibrate, a PPAR-α inhibitor used for treating dyslipidemia, has well-documented anti-inflammatory effects that vary between individuals. While DNA sequence variation explains some of the observed variability in response, epigenetic patterns present another promising avenue of inquiry due to the biological links between the PPAR-α pathway, homocysteine and S-adenosylmethionine - a source of methyl groups for the DNA methylation reaction.

HYPOTHESIS

DNA methylation variation at baseline is associated with the inflammatory response to a short-term fenofibrate treatment.

METHODS

We have conducted the first epigenome-wide study of inflammatory response to daily treatment with 160 mg of micronized fenofibrate over a 3-week period in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN, n = 750). Epigenome-wide DNA methylation was quantified on CD4⁺ T cells using the Illumina Infinium HumanMethylation450 array.

RESULTS

We identified multiple CpG sites significantly associated with the changes in plasma concentrations of inflammatory cytokines such as high sensitivity CRP (hsCRP, 7 CpG sites), IL-2 soluble receptor (IL-2sR, one CpG site), and IL-6 (4 CpG sites). Top CpG sites mapped to KIAA1324L (p = 2.63E-10), SMPD3 (p = 2.14E-08), SYNPO2 (p = 5.00E-08), ILF3 (p = 1.04E-07), PRR3, GNL1 (p = 6.80E-09), FAM50B (p = 3.19E-08), RPTOR (p = 9.79e-07) and several intergenic regions (p < 1.03E-07). We also derived two inflammatory patterns using principal component analysis and uncovered additional epigenetic hits for each pattern before and after fenofibrate treatment.

CONCLUSION

Our study provides preliminary evidence of a relationship between DNA methylation and inflammatory response to fenofibrate treatment.

DNA methylation as a marker of response in rheumatoid arthritis

Rheumatoid arthritis (RA) is a complex disease affecting approximately 0.5-1% of the population. While there are effective biologic therapies, in up to 40% of patients, disease activity remains inadequately controlled. Therefore, identifying factors that predict, prior to the initiation of therapy, which patients are likely to respond best to which treatment is a research priority and DNA methylation is increasingly being explored as a potential theranostic biomarker. DNA methylation is thought to play a role in RA disease pathogenesis and in mediating the relationship between genetic variants and patient outcomes. The role of DNA methylation has been most extensively explored in cancer medicine, where it has been shown to be predictive of treatment response. Studies in RA, however, are in their infancy and, while showing promise, further investigation in well-powered studies is warranted.

Caveolin1 protects against diet induced hepatic lipid accumulation in mice

BACKGROUND AND AIM

Caveolin1 (CAV1) is involved in lipid homeostasis and endocytosis, but little is known about the significance of CAV1 in the pathogenesis and development of nonalcoholic fatty liver disease (NAFLD). This study aimed to determine the role of CAV1 in NAFLD.

METHODS

Expression of CAV1 in the in vitro and in vivo models of NAFLD was analyzed. The effects of CAV1 knockdown or overexpression on free fatty acid (FFA)-induced lipid accumulation in L02 cells and AML12 cells were determined. CAV1 knockout (CAV1-KO) mice and their wild-type (WT) littermates were subjected to a high fat diet (HFD) for 4 weeks, and the functional consequences of losing the CAV1 gene and its subsequent molecular mechanisms were also examined.

RESULTS

Noticeably, CAV1 expression was markedly reduced in NAFLD. CAV1 knockdown led to the aggravation of steatosis that was induced by FFA in both L02 cells and AML12 cells, while CAV1 overexpression markedly attenuated lipid accumulation in the cells. Consistent with CAV1 repression in the livers of HFD-induced mice, the CAV1-KO mice exhibited more severe hepatic steatosis upon HFD intake. In addition, increased cholesterol levels and elevated transaminases were detected in the plasma of CAV1-KO mice. The protein expression of SREBP1, a key gene involved in lipogenesis, was augmented following CAV1 suppression in FFA-treated hepatocytes and in the livers of HFD-fed CAV1-KO mice.

CONCLUSIONS

CAV1 serves as an important protective factor in the development of NAFLD by modulating lipid metabolism gene expression.

Cooperation of Gastric Mononuclear Phagocytes with Helicobacter pylori during Colonization

Helicobacter pylori, the dominant member of the human gastric microbiota, elicits immunoregulatory responses implicated in protective versus pathological outcomes. To evaluate the role of macrophages during infection, we employed a system with a shifted proinflammatory macrophage phenotype by deleting PPARγ in myeloid cells and found a 5- to 10-fold decrease in gastric bacterial loads. Higher levels of colonization in wild-type mice were associated with increased presence of mononuclear phagocytes and in particular with the accumulation of CD11b+F4/80hiCD64+CX3CR1+ macrophages in the gastric lamina propria. Depletion of phagocytic cells by clodronate liposomes in wild-type mice resulted in a reduction of gastric H. pylori colonization compared with nontreated mice. PPARγ-deficient and macrophage-depleted mice presented decreased IL-10-mediated myeloid and T cell regulatory responses soon after infection. IL-10 neutralization during H. pylori infection led to increased IL-17-mediated responses and increased neutrophil accumulation at the gastric mucosa. In conclusion, we report the induction of IL-10-driven regulatory responses mediated by CD11b+F4/80hiCD64+CX3CR1+ mononuclear phagocytes that contribute to maintaining high levels of H. pylori loads in the stomach by modulating effector T cell responses at the gastric mucosa.

Role of Helicobacter pylori infection in pathogenesis of gastric carcinoma

Gastric cancer (GC) is one of the most common carcinoma and the second leading cause of cancer-related deaths worldwide. Helicobacter pylori (H. pylori) infection causes a series of precancerous lesions like gastritis, atrophy, intestinal metaplasia and dysplasia, and is the strongest known risk factor for GC, as supported by epidemiological, preclinical and clinical studies. However, the mechanism of H. pylori developing gastric carcinoma has not been well defined. Among infected individuals, approximately 10% develop severe gastric lesions such as peptic ulcer disease, 1%-3% progresses to GC. The outcomes of H. pylori infection are determined by bacterial virulence, genetic polymorphism of hosts as well as environmental factors. It is important to gain further understanding of the pathogenesis of H. pylori infection for developing more effective treatments for this common but deadly malignancy. The recent findings on the bacterial virulence factors, effects of H. pylori on epithelial cells, genetic polymorphism of both the bacterium and its host, and the environmental factors for GC are discussed with focus on the role of H. pylori in gastric carcinogenesis in this review.

Caveolin-1 is a modulator of fibroblast activation and a potential biomarker for gastric cancer

Stromal fibroblasts play an important role in chronic cancer-related inflammation and the development as well as progression of malignant diseases. However, the difference and relationship between inflammation-associated fibroblasts (IAFs) and cancer-associated fibroblasts (CAFs) are poorly understood. In this study, gastric cancer-associated fibroblasts (GCAFs) and their corresponding inflammation-associated fibroblasts (GIAFs) were isolated from gastric cancer (GC) with chronic gastritis and cultured in vitro. These activated fibroblasts exhibited distinct secretion and tumor-promoting behaviors in vitro. Using proteomics and bioinformatics techniques, caveolin-1 (Cav-1) was identified as a major network-centric protein of a sub-network consisting of 121 differentially expressed proteins between GIAFs and GCAFs. Furthermore, immunohistochemistry in a GC cohort showed significant difference in Cav-1 expression score between GIAFs and GCAFs and among patients with different grades of chronic gastritis. Moreover, silencing of Cav-1 in GIAFs and GCAFs using small interfering RNA increased the production of pro-inflammatory and tumor-enhancing cytokines and chemokines in conditioned mediums that elevated cell proliferation and migration when added to GC cell lines AGS and MKN45 in vitro. In addition, Cav-1 status in GIAFs and GCAFs independently predicted the prognosis of GC. Our findings indicate that Cav-1 loss contributes to the distinct activation statuses of fibroblasts in GC microenvironment and gastritis mucosa, and Cav-1 expression in both GCAFs and GIAFs may serve as a potential biomarker for GC progression.

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori relies on multiple colonization and virulence factors to persist in the human stomach for life. In addition, these factors can be modulated and vary to suit the ever-changing environment within the host individual. This article outlines the novel developments in this field of research during the past year, highlighting the cag pathogenicity island, VacA, γ-glutamyl-transpeptidase as well as including recent advances in protein structure, bacteria-host interaction, and the role of stomach microbiota.