Helicobacter pylori cytotoxin-associated gene A activates tumor necrosis factor-α and interleukin-6 in gastric epithelial cells through P300/CBP-associated factor-mediated nuclear factor-κB p65 acetylation

Targeting macrophage M1 polarization suppression through PCAF inhibition alleviates autoimmune arthritis via synergistic NF-κB and H3K9Ac blockade

Sustained inflammatory invasion leads to joint damage and progressive disability in several autoimmune rheumatic diseases. In recent decades, targeting M1 macrophage polarization has been suggested as a promising therapeutic strategy for autoimmune arthritis. P300/CBP-associated factor (PCAF) is a histone acetyltransferase (HAT) that exhibits a strong positive relationship with the proinflammatory microenvironment. However, whether PCAF mediates M1 macrophage polarization remains poorly studied, and whether targeting PCAF can protect against autoimmune arthritis in vivo remains unclear. Commonly used drugs can cause serious side effects in patients because of their extensive and nonspecific distribution in the human body. One strategy for overcoming this challenge is to develop drug nanocarriers that target the drug to desirable regions and reduce the fraction of drug that reaches undesirable targets. In this study, we demonstrated that PCAF inhibition could effectively inhibit M1 polarization and alleviate arthritis in mice with collagen-induced arthritis (CIA) via synergistic NF-κB and H3K9Ac blockade. We further designed dextran sulfate (DS)-based nanoparticles (DSNPs) carrying garcinol (a PCAF inhibitor) to specifically target M1 macrophages in inflamed joints of the CIA mouse model via SR-A-SR-A ligand interactions. Compared to free garcinol, garcinol-loaded DSNPs selectively targeted M1 macrophages in inflamed joints and significantly improved therapeutic efficacy in vivo. In summary, our study indicates that targeted PCAF inhibition with nanoparticles might be a promising strategy for treating autoimmune arthritis via M1 macrophage polarization inhibition.

Low-grade intestinal metaplasia in Indonesia: Insights into the expression of proinflammatory cytokines during Helicobacter pylori infection and unique East-Asian CagA characteristics

Helicobacter pylori infection is a major cause of intestinal metaplasia. In this study, we aimed to understand the reason underlying the low grade and incidence of intestinal metaplasia in Indonesia, based on the expression of genes encoding proinflammatory cytokines in gastric biopsy specimens. The possible reasons for the lesser virulence of the East-Asian-type CagA in Indonesia than that of the Western-type CagA, which is not common in other countries, were also investigated. The mRNA expression of cytokines was evaluated using real-time PCR. CagA characteristics were analyzed using in silico analysis. The expression of cytokines was typically not robust, among H. pylori-infected subjects in Indonesia, despite them predominantly demonstrating the East-Asian-type CagA. This might partially be explained by the characteristics of the East-Asian-type CagA in Indonesia, which showed a higher instability index and required higher energy to interact with proteins related to the cytokine induction pathway compared with the other types (p < 0.001 and p < 0.05, respectively). Taken together, besides the low prevalence of H. pylori, the low inflammatory response of the host and low CagA virulence, even among populations with high infection rates, may play an essential role in the low grade and low incidence of intestinal metaplasia in Indonesia. We believe that these findings would be relevant for better understanding of intestinal metaplasia, which is closely associated with the development of gastric cancer.

Caulerpin Mitigates Helicobacter pylori-Induced Inflammation via Formyl Peptide Receptors

The identification of novel strategies to control Helicobacter pylori (Hp)-associated chronic inflammation is, at present, a considerable challenge. Here, we attempt to combat this issue by modulating the innate immune response, targeting formyl peptide receptors (FPRs), G-protein coupled receptors that play key roles in both the regulation and the resolution of the innate inflammatory response. Specifically, we investigated, in vitro, whether Caulerpin—a bis-indole alkaloid isolated from algae of the genus Caulerpa—could act as a molecular antagonist scaffold of FPRs. We showed that Caulerpin significantly reduces the immune response against Hp culture filtrate, by reverting the FPR2-related signaling cascade and thus counteracting the inflammatory reaction triggered by Hp peptide Hp(2–20). Our study suggests Caulerpin to be a promising therapeutic or adjuvant agent for the attenuation of inflammation triggered by Hp infection, as well as its related adverse clinical outcomes.

The role of PKM2 nuclear translocation in the constant activation of the NF-κB signaling pathway in cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) play critical roles in cancer progression by regulating tumor cell proliferation, angiogenesis, and metastasis. Recent studies demonstrated that CAFs induce inhibitory immune cell infiltration and chemotherapy resistance in gastric cancer by activating the NF-κB signaling pathway to secrete IL6, IL8, and other inflammatory factors. Inhibition of the NF-κB signaling pathway in CAFs might be a potential therapeutic strategy in gastric cancer. However, how the NF-κB pathway is activated in CAFs remains unclear. We showed that mesenchymal stem cells (MSCs) differentiated into CAFs, induced by the exosomes derived from gastric cancer cells. During the process of differentiation from MSCs into CAFs, we showed that nuclear PKM2 expression was continuously upregulated and associated with NF-κB P65 acetylation, contributing to P65 nuclear retention in CAFs and constant transcription of IL-6, IL-8, and other inflammatory factors, thus promoting gastric cancer cell proliferation. We showed that NF-κB P65 acetylation was induced by P300. We showed that nuclear PKM2 was derived from exosomes of gastric cancer cell lines and the positive feedback loop induced by PKM2-P65 combination. It is also proved that P300 inhibitors can inhibit tumor proliferation in an AGS subcutaneous xenograft tumor model. Our study showed that gastric cancer cells influence the continuous activation of the NF-κB signaling pathway in CAFs by secreting gastric cancer exosomes containing PKM2, thus inducing abnormal metabolism and inflammation activation. This study provides a new therapeutic target for CAF normalization or deactivation strategies.

Effects of choline supplementation on liver biology, gut microbiota, and inflammation in Helicobacter pylori-infected mice

AIMS

Diet is one of the factors affecting the pathogenicity of Helicobacter pylori (H. pylori) infection. Choline is a dietary component that is crucial for normal cellular function. However, choline intake imbalance can lead to liver injury, inflammation, and changes of the gut microbiota composition. The study aimed to explore the effects of choline supplementation on liver biology, gut microbiota, and inflammation in H. pylori-infected mice.

MAIN METHODS

Liver function was detected by biochemical and histopathological analysis. Serum inflammatory markers were measured using ELISA. Fecal microbial profiles were determined via 16S rRNA sequencing.

KEY FINDINGS

The results showed that choline supplementation decreased serum LDL level, while increased the activities of serum AST and ALT in normal BALB/c mice. Besides, choline also reduced hepatic SOD and GSH-Px activities, and elevated hepatic MDA level of H. pylori-infected mice. Moreover, choline markedly enhanced the concentrations of inflammatory factors including LPS, CRP, IL-6, TNF-α, and CXCL1 in H. pylori-infected mice. Meanwhile, choline and H. pylori cotreatment altered the richness and diversity of the mice gut microbiota, and increased the relative abundance of Escherichia_Shigella, which had a significant positive correlation with the levels of LPS, CRP, IL-6, TNF-α and CXCL1.

SIGNIFICANCE

Our data suggest, for the first time, that choline can aggravate H. pylori-induced inflammation, which may be associated with the alterations of gut microbiota. This study may provide novel insights into the possible effects of food-derived choline on H. pylori infection-related diseases.

Expression of tryptophan hydroxylase in gastric mucosa in symptomatic and asymptomatic Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori infection induces clinical symptoms in 15-20% of subjects, and the reason for this variation is still not clear. The aim of the present study is to evaluate the expression of tryptophan hydroxylase (TpH-1) in gastric mucosa of patients with symptomatic and asymptomatic H. pylori infection in relation to the intensity of bacterial colonization and severity of dyspeptic symptoms.

MATERIAL AND METHODS

Ninety subjects (aged 35-49 years) were enrolled in the study and separated into 3 groups of 30 subjects each. Group I - healthy volunteers without H. pylori infection, group II - subjects with asymptomatic H. pylori infection, group III - H. pylori-infected patients with dyspeptic symptoms, mainly fasting and nocturnal epigastric pain. To diagnose H. pylori infection the urea breath test (UBT-13C) and histological analysis were performed. The level of mRNA expression of tryptophan hydroxylase (TpH-1) was estimated in gastric mucosa with RT-PCR.

RESULTS

The expression of this enzyme in antral mucosa was 2.69 ±0.97 in group I, 2.28 ±0.69 in group II (p > 0.05) and 4.40 ±1.64 in group III (p < 0.001). The levels of expression of TpH-1 in gastric body mucosa were 2.16 ±0.70, 1.57 ±0.52 (p > 0.05) and 3.40 ±1.51 (p < 0.001), respectively. In group III a positive correlation was found between intensity of H. pylori colonization and TpH-1 expression as well as between TpH-1 expression and severity of dyspeptic symptoms.

CONCLUSIONS

Increased expression of TpH-1 in gastric mucosa plays a role in pathogenesis of chronic dyspepsia.

H. pylori infection induced BMAL1 expression and rhythm disorder aggravate gastric inflammation

BACKGROUND

Rhythm abnormalities are crucial for diverse diseases. However, their role in disease progression induced by Helicobacter pylori (H. pylori) remains elusive.

METHODS

H. pylori infection was used in in vivo and in vitro experiments to examine its effect on rhythmic genes. The GEO database was used to screen H. pylori affecting rhythm genes, and the effect of rhythm genes on inflammatory factors. Chromatin immunoprecipitation and dual luciferase assays were used to further find out the regulation between molecules. Animal models were used to confirm the relationship between rhythm genes and H. pylori-induced inflammation.

FINDINGS

BMAL1 disorders aggravate inflammation induced by H. pylori. Specifically, H. pylori induce BMAL1 expression in vitro and in vivo through transcriptional activation of LIN28A, breaking the circadian rhythm. Mechanistically, LIN28A binds to the promoter region of BMAL1 and directly activates its transcription under H. pylori infection. BMAL1 in turn functions as a transcription factor and enhances the expression of proinflammatory cytokine TNF-α, thereby promoting inflammation. Of note, BMAL1 dysfunction in the rhythm disorder animal model aggravates inflammatory response induced by H. pylori infection in vivo.

INTERPRETATION

These findings in this study imply the pathogenic relationship between BMAL1 and H. pylori. BMAL1 may serve as a potential diagnostic marker and therapeutic target for the early diagnosis and treatment of diseases related to H. pylori infection. FUND: National Natural Science Foundation of China.

Role of NOD1 and ALPK1/TIFA Signalling in Innate Immunity Against Helicobacter pylori Infection

The human pathogen Helicobacter pylori interacts intimately with gastric epithelial cells to induce inflammatory responses that are a hallmark of the infection. This inflammation is a critical precursor to the development of peptic ulcer disease and gastric cancer. A major driver of this inflammation is a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI), present in a subpopulation of more virulent H. pylori strains. The cagPAI T4SS specifically activates signalling pathways in gastric epithelial cells that converge on the transcription factor, nuclear factor-κB (NF-κB), which in turn upregulates key immune and inflammatory genes, resulting in various host responses. It is now clear that H. pylori possesses several mechanisms to activate NF-κB in gastric epithelial cells and, moreover, that multiple signalling pathways are involved in these responses. Two of the dominant signalling pathways implicated in NF-κB-dependent responses in epithelial cells are nucleotide-binding oligomerisation domain 1 (NOD1) and a newly described pathway involving alpha-kinase 1 (ALPK1) and tumour necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain (TIFA). Although the relative roles of these two pathways in regulating NF-κB-dependent responses still need to be clearly defined, it is likely that they work cooperatively and non-redundantly. This chapter will give an overview of the various mechanisms and pathways involved in H. pylori induction of NF-κB-dependent responses in gastric epithelial cells, including a 'state-of-the-art' review on the respective roles of NOD1 and ALPK1/TIFA pathways in these responses.

Involvement of Aryl Hydrocarbon Receptor and Aryl Hydrocarbon Receptor Repressor in Helicobacter Pylori-related Gastric Pathogenesis

Background: Persistent Helicobacter pylori (H. pylori) infection leads to various gastric diseases. Multiple studies have demonstrated that aryl hydrocarbon receptor (AHR) plays roles in the antibacterial response and aryl hydrocarbon receptor repressor (AHRR) is downregulated in stomach cancer. However, the role of AHR or AHRR in H. pylori-related gastric diseases remains unclear. Aims: To investigate whether AHR or AHRR is involved in H. pylori-related gastric diseases. Methods: Patients with gastritis or gastric adenocarcinoma were enrolled randomly, and gastric tissue specimens were diagnosed pathologically. AHR, AHRR, and H. pylori infection status in tissues were detected by immunohistochemistry. Human gastric cells were cocultured with H. pylori. siRNAs were used to silence AHR or AHRR, and a C57bl/6 mouse model colonized by H. pylori was established. Protein expression was determined by western blotting analysis, and TNF, IL-8 and IL-1β in cell supernatants were measured by ELISA. Results: AHR and AHRR were expressed in gastritis tissues and gastric cancer tissues without H. pylori infection, and principally located in the cytoplasm and nucleus. AHR expression was significantly correlated with AHRR expression in gastric tissues without H. pylori infection (P=0.008). However, their expressions were negatively correlated with H. pylori infection status. H. pylori coculture inhibited AHR and AHRR expression in stomach mucosa in vitro and in vivo. Gastric cells produced more TNF, IL-8 and IL-1β when AHR or AHRR was silenced. Conclusions: This preliminary study indicates that AHR and AHRR may be involved in H. pylori-related gastric pathogenesis, and helps toward understanding of inflammation-initiated carcinogenesis of gastric cancer.

Role of Δ133p53 isoform in NF-κB inhibitor PDTC-mediated growth inhibition of MKN45 gastric cancer cells

AIM

To investigate the role of Δ133p53 isoform in nuclear factor-κB (NF-κB) inhibitor pyrrolidine dithiocarbamate (PDTC)-mediated growth inhibition of MKN45 gastric cancer cells.

METHODS

The growth rate of MKN45 cells after treatment with different concentrations of only PDTC or PTDC in combination with cisplatin was detected by the CCK-8 assay. mRNA expression levels of Δ133p53, p53β, and the NF-κB p65 subunit and p65 protein levels were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence, respectively. Growth of MKN45 cells was significantly inhibited by PDTC alone in a dose-dependent manner (P < 0.01). Moreover, the inhibitory effect of cisplatin was remarkably enhanced in a dose-dependent manner by co-treatment with PDTC (P < 0.01).

RESULTS

RT-PCR analysis revealed that mRNA expression of p65 was curbed significantly in a dose-dependent manner by treatment with only PDTC (P < 0.01), and this suppressive effect was further enhanced when co-treated with cisplatin (P < 0.01). With respect to the other p53 isoforms, mRNA level of Δ133p53 was significantly reduced in a dose-dependent manner by treatment with only PDTC or PTDC in combination with cisplatin (P < 0.01), whereas p53β mRNA expression was not altered by PDTC treatment (P > 0.05). A similar tendency of change in p65 protein expression, as observed for the corresponding mRNA, was detected by immunofluorescence analysis (P < 0.01). Pearson correlation analysis demonstrated that Δ133p53 and p65 mRNA expression levels were positively related, while no significant relationship was observed between those of p65 and p53β (r = 0.076, P > 0.01).

CONCLUSION

Δ133p53 isoform (not p53β) is required in PDTC-induced inhibition of MKN45 gastric cancer cells, indicating that disturbance in the cross-talk between p53 and NF-κB pathways is a promising target in pharmaceutical research for the development of treatment strategies for gastric cancer.