Cathelicidin protects against Helicobacter pylori colonization and the associated gastritis in mice

Downregulation of PDIA3 inhibits gastric cancer cell growth through cell cycle regulation

OBJECTIVE

Protein disulfide isomerase A3 (PDIA3) promotes the correct folding of newly synthesized glycoproteins in the endoplasmic reticulum. PDIA3 is overexpressed in most tumors, and it may become a biomarker of cancer prognosis and immunotherapy. Our study aims to detect the expression level of PDIA3 in gastric cancer (GC) and its association with GC development as wells as the underlying mechanisms.

METHODS

GC cell lines with PDIA3 knockdown by siRNA, CRISPR-cas9 sgRNAs or a pharmacological inhibitor of LOC14 were prepared and used. PDIA3 knockout GC cells were established by CRISPR-cas9-PDIA3 system. The proliferation, migration, invasion and cell cycle of GC cells were analyzed by cell counting kit-8 assay, wound healing assay, transwell assay and flow cytometry, respectively. Immunodeficient nude mice was used to evaluate the role of PDIA3 in tumor formation. Quantitative PCR and western blot were used for examining gene and protein expressions. RNA sequencing was performed to see the altered gene expression.

RESULTS

The expressions of PDIA3 in GC tissues and cells were increased significantly, and its expression was negatively correlated with the three-year survival rate of GC patients. Down-regulation of PDIA3 by siRNA, LOC14 or CRISPR-cas9 significantly inhibited proliferation, invasion and migration of GC cells TMK1 and AGS, with cell cycle arrested at G2/M phase. Meanwhile, decreased PDIA3 significantly inhibited growth of tumor xenograft in vivo. It was found that cyclin G1 (encoded by CCNG1 gene) expression was decreased by downregulation of PDIA3 in GC cells both in vitro and in vivo. In addition, protein levels of other cell cycle related factors including cyclin D1, CDK2, and CDK6 were also significantly decreased. Further study showed that STAT3 was associated with PDIA3-mediated cyclin G1 regulation.

CONCLUSION

PDIA3 plays an oncogenic role in GC. Our findings unfolded the functional role of PDIA3 in GC development and highlighted a novel target for cancer therapeutic strategy.

Recent Advances in Vitamin D3 Intervention to Eradicate Helicobacter pylori Infection

Helicobacter pylori (HP) infections affect approximately one-third of children worldwide. In China, the incidence of HP infection in children ranges from approximately 30% to 60%. In addition to damaging the gastrointestinal tract mucosa, HP infection in children can negatively affect their growth and development, hematology, respiratory and hepatobiliary system, skin, nutritional metabolism, and autoimmune system. However, the rate of HP eradication also fell considerably from the previous rate due to the presence of drug-resistant HP strains and the limited types of antibiotics that can be used in young patients. Vitamin D3 (VitD3) is a steroid hormone that can reduce inflammation in the stomach mucosa induced by HP and can alleviate and eradicate HP through a variety of pathways and mechanisms, including immune regulation and the stimulation of antimicrobial peptide (AMP) secretion and Ca2+ influx, to reestablish lysosomal acidification; thus, these results provide new strategies and ideas for the eradication of drug-resistant HP strains.

Control of Helicobacter pylori with engineered probiotics secreting selective guided antimicrobial peptides

Helicobacter pylori is the primary cause of 78% of gastric cancer cases, providing an opportunity to prevent cancer by controlling a single bacterial pathogen within the complex gastric microbiota. We developed highly selective antimicrobial agents against H. pylori by fusing an H. pylori-binding guide peptide (MM1) to broad-spectrum antimicrobial peptides. The common dairy probiotic Lactococcus lactis was then engineered to secrete these guided antimicrobial peptides (gAMPs). When co-cultured in vitro with H. pylori, the gAMP probiotics lost no toxicity compared to unguided AMP probiotics against the target, H. pylori, while losing >90% of their toxicity against two tested off-target bacteria. To test binding to H. pylori, the MM1 guide was fused to green fluorescent protein (GFP), resulting in enhanced binding compared to unguided GFP as measured by flow cytometry. In contrast, MM1-GFP showed no increased binding over GFP against five different off-target bacteria. These highly selective gAMP probiotics were then tested by oral gavage in mice infected with H. pylori. As a therapy, the probiotics outperformed antibiotic treatment, effectively eliminating H. pylori in just 5 days, and also protected mice from challenge infection as a prophylactic. As expected, the gAMP probiotics were as toxic against H. pylori as the unguided AMP probiotics. However, a strong rebound in gastric species diversity was found with both the selective gAMP probiotics and the non-selective AMP probiotics. Eliminating the extreme microbial dysbiosis caused by H. pylori appeared to be the major factor in diversity recovery. IMPORTANCE Alternatives to antibiotics in the control of Helicobacter pylori and the prevention of gastric cancer are needed. The high prevalence of H. pylori in the human population, the induction of microbial dysbiosis by antibiotics, and increasing antibiotic resistance call for a more sustainable approach. By selectively eliminating the pathogen and retaining the commensal community, H. pylori control may be achieved without adverse health outcomes. Antibiotics are typically used as a therapeutic post-infection, but a more targeted, less disruptive approach could be used as a long-term prophylactic against H. pylori or, by extension, against other gastrointestinal pathogens. Furthermore, the modular nature of the guided antimicrobial peptide (gAMP) technology allows for the substitution of different guides for different pathogens and the use of a cocktail of gAMPs to avoid the development of pathogen resistance.

LncRNA RP11-93B14.5 promotes gastric cancer cell growth through PI3K/AKT signaling pathway

OBJECTIVE

Emerging evidence indicates that long non-coding RNA (lncRNA) RP11-93B14.5 facilitates tumor progression in variety of malignancies. The present study proposed to study the functional effect of lncRNA RP11-93B14.5 in gastric cancer (GC) as well as the underlying mechanism.

METHODS

Bioinformatics analysis was utilized to analyze lncRNA expression in GC tissues. siRNA was used for knockdown of RP11-93B14.5 in GC cells MKN45 and KATO III. The stable knockdown cell lines were constructed by CRISPR-Cas9. Cell counting kit-8 (CCK-8) assay and soft agar colony formation assay were used to analyze GC cell viability. Flow cytometry analysis was performed to analyze the cell cycle distribution of MKN45 and KATO III. RNA sequencing (RNA-seq) was employed to detect differential genes after transfection with siRP11-93B14.5. Quantitative PCR (Q-PCR) was used to examine gene expression in GC cell lines. Western-blot assay was used to measure protein levels. RNA fluorescent in situ hybridization (FISH) was conducted for lncRNA cellular location and expression.

RESULTS

Based on the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database, RP11-93B14.5 was upregulated in GC tissue, which was also verified in GC cell lines in comparison to the normal gastric epithelial HFE145 cells. Knockdown of RP11-93B14.5 decreased cell viability and the colony number of MKN45 and KATO III cells, and altered cell cycle distribution in vitro. RNA-seq analysis revealed RP11-93B14.5 may modulate genes expression of S100A2 and TIMP2 in MKN45 and KATO III cells. Mechanistically, RP11-93B14.5 may drive the progression of GC via S100A2 related-PI3K/AKT signaling pathway.

CONCLUSIONS

LncRNA RP11-93B14.5 knockdown alleviated the malignant phenotypes of GC cells through regulating PI3K/AKT. Our results provide evidence for the role of lncRNAs in regulating tumor progression.

Strategies adopted by gastric pathogen Helicobacter pylori for a mature biofilm formation: Antimicrobial peptides as a visionary treatment

Enormous efforts in recent past two decades to eradicate the pathogen that has been prevalent in half of the world's population have been problematic. The biofilm formed by Helicobacter pylori provides resistance towards innate immune cells, various combinatorial antibiotics, and human antimicrobial peptides, despite the fact that these all are potent enough to eradicate it in vitro. Biofilm provides the opportunity to secrete various virulence factors that strengthen the interaction between host and pathogen helping in evading the innate immune system and ultimately leading to persistence. To our knowledge, this review is the first of its kind to explain briefly the journey of H. pylori starting with the chemotaxis, the mechanism for selecting the site for colonization, the stress faced by the pathogen, and various adaptations to evade these stress conditions by forming biofilm and the morphological changes acquired by the pathogen in mature biofilm. Furthermore, we have explained the human GI tract antimicrobial peptides and the reason behind the failure of these AMPs, and how encapsulation of Pexiganan-A(MSI-78A) in a chitosan microsphere increases the efficiency of eradication.

Immune Biology and Persistence of Helicobacter pylori in Gastric Diseases

Helicobacter pylori is a prevalent pathogen, which affects more than 40% of the global population. It colonizes the human stomach and persists in its host for several decades or even a lifetime, if left untreated. The persistent infection has been linked to various gastric diseases, including gastritis, peptic ulcers, and an increased risk for gastric cancer. H. pylori infection triggers a strong immune response directed against the bacterium associated with the infiltration of innate phagocytotic immune cells and the induction of a Th1/Th17 response. Even though certain immune cells seem to be capable of controlling the infection, the host is unable to eliminate the bacteria as H. pylori has developed remarkable immune evasion strategies. The bacterium avoids its killing through innate recognition mechanisms and manipulates gastric epithelial cells and immune cells to support its persistence. This chapter focuses on the innate and adaptive immune response induced by H. pylori infection, and immune evasion strategies employed by the bacterium to enable persistent infection.

Human cathelicidin LL-37 exerts amelioration effects against EHEC O157:H7 infection regarding inflammation, enteric dysbacteriosis, and impairment of gut barrier function

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 infection impairs intestinal barrier function, causing intestinal inflammation and enteric dysbacteriosis. The human cathelicidin LL-37 can regulate excessive inflammatory responses, barrier function, and balance the intestinal microbial community; however, little is known about its effects on inflammation, intestinal barrier function, and microbiota disorders in EHEC O157:H7-infected mice. In this study, we investigated the protective effect of LL-37 against EHEC O157:H7 infection and elucidated the underlying mechanism using a mouse model. LL-37 treatment was found to inhibit body weight loss, restore edema and destruction of the intestinal villi, and significantly reduce epithelial apoptosis (P < 0.05) in EHEC O157:H7-infected mice. Furthermore, inflammatory infiltration of macrophages and neutrophils into the jejunum and colon was significantly decreased (P < 0.05). LL-37 significantly downregulated the production of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) (P < 0.05) and upregulated the anti-inflammatory cytokine (IL-10) during EHEC O157:H7 infection. LL-37 increased the expression of tight junction proteins (ZO-1, ZO-2, claudin-1, and occludin), which are associated with intestinal barrier function, and had a positive effect on EHEC O157:H7-induced microbial disorders, particularly in terms of the inflammation-related microbiota. LL-37 also significantly decreased the E. coli load in the liver and spleen (P < 0.01) and restored the structure of the liver and kidney. Taken together, LL-37 conferred protection in a EHEC O157:H7-induced mouse model by reducing intestinal inflammation, enhancing intestinal barrier function, and restoring the balance of the intestinal microbiota, which indicates the therapeutic potential of LL-37 against pathogen infection.

Vitamin D3 eradicates Helicobacter pylori by inducing VDR-CAMP signaling

Background

Vitamin D₃ [VitD₃, 1,25 (OH)₂D₃] is known to have immunomodulatory and anti-microbial properties; however, its activity against Helicobacter pylori is unclear. In this study, we established H. pylori infection models in wild-type and VitD₃ receptor (VDR) knockdown mice and analyzed the effects of VitD₃ and their underlying mechanisms.

Methods

VDR^+/+ and VDR^+/- mice were intragastrically infected with the H. pylori SS1 strain. After confirmation of H. pylori infection, mice were treated with different doses of VitD₃. The infection levels in stomach tissues were quantified using the colony-forming assay, and the expression levels of the VDR and cathelicidin antimicrobial peptide (CAMP) in the gastric mucosa were analyzed by immunohistochemistry and western blotting.

Results

The gastric mucosa of VDR^+/- mice was more susceptible to H. pylori colonization and had lower levels of VDR and CAMP expression than that of VDR^+/+ mice. H. pylori infection upregulated VDR and CAMP expression in the stomach of both wild-type and mutant mice, and VitD₃ treatment resulted in further increase of VDR and CAMP levels, while significantly and dose-dependently decreasing the H. pylori colonization rate in both mouse groups, without affecting blood calcium or phosphorus levels.

Conclusion

Our data indicate that oral administration of VitD₃ reduces the H. pylori colonization rate and upregulates VDR and CAMP expression in the gastric mucosa, suggesting a role for VitD₃/VDR/CAMP signaling in the eradication of H. pylori in the stomach. These findings provide important insights into the mechanism underlying the anti-H. pylori activity of VitD₃ and should be useful in the development of measures to eradicate H. pylori.

Host Cell Antimicrobial Responses against Helicobacter pylori Infection: From Biological Aspects to Therapeutic Strategies

The colonization of Helicobacter pylori (H. pylori) in human gastric mucosa is highly associated with the occurrence of gastritis, peptic ulcer, and gastric cancer. Antibiotics, including amoxicillin, clarithromycin, furazolidone, levofloxacin, metronidazole, and tetracycline, are commonly used and considered the major treatment regimens for H. pylori eradication, which is, however, becoming less effective by the increasing prevalence of H pylori resistance. Thus, it is urgent to understand the molecular mechanisms of H. pylori pathogenesis and develop alternative therapeutic strategies. In this review, we focus on the virulence factors for H. pylori colonization and survival within host gastric mucosa and the host antimicrobial responses against H. pylori infection. Moreover, we describe the current treatments for H. pylori eradication and provide some insights into new therapeutic strategies for H. pylori infection.

Alterations in Intestinal Microbiota Composition in Mice Treated With Vitamin D3 or Cathelicidin

Gut microbiota is a complex aggregation of microbial organisms, which offers diverse protective benefits to the host. Dysbiosis of intestinal microbiota is frequently associated with many diseases. Vitamin D3 (VD), which was originally associated with bone health, also possesses antimicrobial activities and can act through antimicrobial peptide. Cathelicidin is a type of antimicrobial peptide in host to maintain the balance of gut microbiome. Our current study sought to evaluate the protective effect of VD and cathelicidin in mice intestines by administration of VD or mCRAMP-encoding L. lactis. We herein provided a comprehensive profile of the impact of VD and mCRAMP on gut microbiota using 16S rRNA sequencing, followed by bioinformatics and statistical analysis. Our results revealed an increased richness of bacterial community in mice intestines due to VD administration. Moreover, we showed a beneficial effect of VD and mCRAMP by enhancing the colonization of bacterial taxa that are associated with protective effects to the host but repressing the propagation of bacterial taxa that are associated with harmful effects to the host. Various metabolic pathways related to amino acid and lipid metabolism were affected in this process. We further established a bacterial panel as a reliable biomarker to evaluate the efficacy of remodeling the mice gut microbiota by VD and mCRAMP administration. The uncovered effects will deepen the comprehension about the antibacterial mechanisms of VD and mCRAMP and provide new insights for therapeutic implication of them.

Antimicrobial peptides and the gut microbiome in inflammatory bowel disease

Antimicrobial peptides (AMP) are highly diverse and dynamic molecules that are expressed by specific intestinal epithelial cells, Paneth cells, as well as immune cells in the gastrointestinal (GI) tract. They play critical roles in maintaining tolerance to gut microbiota and protecting against enteric infections. Given that disruptions in tolerance to commensal microbiota and loss of barrier function play major roles in the pathogenesis of inflammatory bowel disease (IBD) and converge on the function of AMP, the significance of AMP as potential biomarkers and novel therapeutic targets in IBD have been increasingly recognized in recent years. In this frontier article, we discuss the function and mechanisms of AMP in the GI tract, examine the interaction of AMP with the gut microbiome, explore the role of AMP in the pathogenesis of IBD, and review translational applications of AMP in patients with IBD.

Three-Decade Failure to the Eradication of Refractory Helicobacter pylori Infection and Recent Efforts to Eradicate the Infection

BACKGROUND

Helicobacter pylori causes dangerous and deadly diseases such as gastric cancer and duodenal ulcers. Eradication and treatment of this bacterium are very important due to the deadly diseases caused by H. pylori and the high cost of treatment for countries.

METHODS

Thus, we present a complete list of the most important causes of failure in the treatment and eradication of H. pylori, and address new therapeutic methods that may be effective in controlling this bacterium in the future.

RESULTS

Many efforts have been made to control and eradicate this bacterium over the years, but no success has been achieved since its eradication is a complex process affected by the bacterial properties and host factors. Previous studies have shown that various factors are involved in the failure to eradicate H. pylori, such as new genotypes of the bacterium with higher pathogenicity, inappropriate patient cooperation, mutations, biofilm formation and dormant forms that cause antibiotic resistance, acidic stomach pH, high bacterial load, smoking, immunosuppressive features and intracellular occurrence of H. pylori. On the other hand, recent studies reported that the use of probiotics, nanoparticles, antimicrobial peptides, natural product and vaccines can be helpful in the treatment and eradication of H. pylori infections.

CONCLUSION

Eradication of H. pylori is crucial for the treatment of important diseases such as gastric cancer. Therefore, it seems that identifying the failure causes of treating this bacterium can be helpful in controlling the infections. Besides, further studies on new therapeutic strategies may help eradicate H. pylori in the future.

Lactobacillus plantarum ZJ316 Attenuates Helicobacter pylori-Induced Gastritis in C57BL/6 Mice

Helicobacter pylori is a highly prevalent human-specific pathogen that causes various gastric diseases. In the present study, Lactobacillus plantarum ZJ316, which could survive well in simulated gastrointestinal conditions, was found to have significant anti-H. pylori ability. Animal assays revealed that L. plantarum ZJ316 had preventive and therapeutic effects on H. pylori-induced gastritis. L. plantarum ZJ316 significantly decreased interferon γ (IFN-γ) and interleukin 6 (IL-6) levels, increased the IL-10 level, and repaired mucosal damage. Moreover, 16S rRNA gene sequencing revealed that the relative abundance of H. pylori could be significantly reduced by L. plantarum ZJ316 administration. Members of the families Dehalobacteriaceae and Geodermatophilaceae were more prevalent in the prevention group, while Lactobacillaceae and Actinomycetaceae were more prevalent in the treatment group. These results indicate that L. plantarum ZJ316 serves as a potential candidate for the prevention and treatment of H. pylori-induced gastritis by regulating the gastric microbiota and reducing mucosal inflammation.

Vitamin D3 Inhibits Helicobacter pylori Infection by Activating the VitD3/VDR-CAMP Pathway in Mice

Helicobacter pylori (H. pylori) infection is closely associated with the occurrence and development of gastric diseases. Therefore, eliminating H. pylori infection should help to prevent gastric diseases. Vitamin D3 (VitD3, 1,25(OH)₂D₃) was previously observed to exhibit anti-H. pylori infection activity in clinic, but these results were reported in heterogeneous in vivo studies without elucidation of the underlying mechanisms. In the present study, we established H. pylori infection models in both wild-type and VDR knockdown (VDR^-KD) mice, which were used to demonstrate that VitD3 inhibits H. pylori infection by enhancing the expression of VitD receptor (VDR) and cathelicidin antimicrobial peptide (CAMP). Furthermore, VDR^-KD mice that exhibited lower VDR expression were more susceptible to H. pylori infection. In cultured mouse primary gastric epithelial cells, we further demonstrated that the VitD3/VDR complex binds to the CAMP promoter region to increase its expression. These data provide a mechanistic explanation of the anti-H. pylori infection activity of VitD3 at the molecular level in mice and suggest a new avenue for the clinical management of H. pylori eradication therapy.

Cathelicidin preserves intestinal barrier function in polymicrobial sepsis

Objectives

The intestinal epithelium compartmentalizes the sterile bloodstream and the commensal bacteria in the gut. Accumulating evidence suggests that this barrier is impaired in sepsis, aggravating systemic inflammation. Previous studies reported that cathelicidin is differentially expressed in various tissues in sepsis. However, its role in sepsis-induced intestinal barrier dysfunction has not been investigated.

Design

To examine the role of cathelicidin in polymicrobial sepsis, cathelicidin wild-(Cnlp^+/+) and knockout (Cnlp^−/−) mice underwent cecal-ligation and puncture (CLP) followed by the assessment of septic mortality and morbidity as well as histological, biochemical, immunological, and transcriptomic analyses in the ileal tissues. We also evaluated the prophylactic and therapeutic efficacies of vitamin D3 (an inducer of endogenous cathelicidin) in the CLP-induced murine polymicrobial sepsis model.

Results

The ileal expression of cathelicidin was increased by three-fold after CLP, peaking at 4 h. Knockout of Cnlp significantly increased 7-day mortality and was associated with a higher murine sepsis score. Alcian-blue staining revealed a reduced number of mucin-positive goblet cells, accompanied by reduced mucin expression. Increased number of apoptotic cells and cleavage of caspase-3 were observed. Cnlp deletion increased intestinal permeability to 4kD fluorescein-labeled dextran and reduced the expression of tight junction proteins claudin-1 and occludin. Notably, circulating bacterial DNA load increased more than two-fold. Transcriptome analysis revealed upregulation of cytokine/inflammatory pathway. Depletion of Cnlp induced more M1 macrophages and neutrophils compared with the wild-type mice after CLP. Mice pre-treated with cholecalciferol (an inactive form of vitamin D3) or treated with 1alpha, 25-dihydroxyvitamin D3 (an active form of VD3) had decreased 7-day mortality and significantly less severe symptoms. Intriguingly, the administration of cholecalciferol after CLP led to worsened 7-day mortality and the associated symptoms.

Conclusions

Endogenous cathelicidin promotes intestinal barrier integrity accompanied by modulating the infiltration of neutrophils and macrophages in polymicrobial sepsis. Our data suggested that 1alpha, 25-dihydroxyvitamin D3 but not cholecalciferol is a potential therapeutic agent for treating sepsis.

Review of antimicrobial peptides with anti-Helicobacter pylori activity

BACKGROUND

The emergence of antibiotic-resistant Helicobacter pylori strains in recent years has increased the need for finding an alternative in the post-antibiotic era. One of the fields being considered for this purpose is antimicrobial peptides. The aim of this review was to provide an obvious scheme from the studied anti-H. pylori peptides and to investigate their common features.

METHOD

First, all of the antimicrobial peptides with their anti-H. pylori effects have been proved up to September 2018 were selected and their information including structure, mechanism of action, and function was reviewed. To achieve this, three databases of PubMed, Scopus, and Web of science were used.

RESULTS

A total of 9 groups containing 22 antimicrobial peptides were found with demonstrated anti-H. pylori effects. The nine groups included pexiganan, tilapia piscidins, epinecidin-1, cathelicidins, defensins, bicarinalin, odorranain-HP, PGLa-AM1, and bacteriocins. Most of the antimicrobial peptides, not all, had common features such as the ability to kill antibiotic-resistant strains, having α-helical structure, being cationic, with high positive charge and isoelectric point.

CONCLUSION

Antimicrobial peptides with anti-H. pylori effects have the potential to replace the antibiotics, especially in the post-antibiotic era, if a rapid and low-cost production method would be found.

Vitamin D3 activates the autolysosomal degradation function against Helicobacter pylori through the PDIA3 receptor in gastric epithelial cells

Helicobacter pylori (H. pylori) is a common human pathogenic bacterium. Once infected, it is difficult for the host to clear this organism using the innate immune system. Increased antibiotic resistance further makes it challenging for effective eradication. However, the mechanisms of immune evasion still remain obscure, and novel strategies should be developed to efficiently eliminate H. pylori infection in stomachs. Here we uncovered desirable anti-H. pylori effect of vitamin D3 both in vitro and in vivo, even against antibiotic-resistant strains. We showed that H. pylori can invade into the gastric epithelium where they became sequestered and survived in autophagosomes with impaired lysosomal acidification. Vitamin D3 treatment caused a restored lysosomal degradation function by activating the PDIA3 receptor, thereby promoting the nuclear translocation of PDIA3-STAT3 protein complex and the subsequent upregulation of MCOLN3 channels, resulting in an enhanced Ca²⁺ release from lysosomes and normalized lysosomal acidification. The recovered lysosomal degradation function drives H. pylori to be eliminated through the autolysosomal pathway. These findings provide a novel pathogenic mechanism on how H. pylori can survive in the gastric epithelium, and a unique pathway for vitamin D3 to reactivate the autolysosomal degradation function, which is critical for the antibacterial action of vitamin D3 both in cells and in animals, and perhaps further in humans. Abbreviations: 1,25D3: 1α, 25-dihydroxyvitamin D3; ATG5: autophagy related 5; Baf A1: bafilomycin A₁; BECN1: beclin 1; CagA: cytotoxin-associated gene A; CFU: colony-forming unit; ChIP-PCR: chromatin immunoprecipitation-polymerase chain reaction; Con A: concanamycin A; CQ: chloroquine; CRISPR: clustered regularly interspaced short palindromic repeats; CTSD: cathepsin D; GPN: Gly-Phe-β-naphthylamide; H. pylori: Helicobacter pylori; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MCOLN1: mucolipin 1; MCOLN3: mucolipin 3; MCU: mitochondrial calcium uniporter; MOI: multiplicity of infection; NAGLU: N-acetyl-alpha-glucosaminidase; PDIA3: protein disulfide isomerase family A member 3; PMA: phorbol 12-myristate 13-acetate; PRKC: protein kinase C; SQSTM1: sequestosome 1; STAT3: signal transducer and activator of transcription 3; SS1: Sydney Strain 1; TRP: transient receptor potential; VacA: vacuolating cytotoxin; VD3: vitamin D3; VDR: vitamin D receptor.

Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori

Evasion of autophagy is key for intracellular survival of bacteria in host cells, but its involvement in persistent infection by Helicobacter pylori, a bacterium identified to invade gastric epithelial cells, remains obscure. The aim of this study was to functionally characterize the role of autophagy in H. pylori infection. Autophagy was assayed in H. pylori-infected human gastric epithelium and the functional role of autophagy was determined via genetic or pharmacological ablation of autophagy in mouse and cell line models of H. pylori infection. Here, we showed that H. pylori inhibited lysosomal function and thereby promoted the accumulation of autophagosomes in gastric epithelial cells. Importantly, inhibiting autophagosome formation by pharmacological inhibitors or genetic ablation of BECN1 or ATG5 reduced H. pylori intracellular survival, whereas inhibition of lysosomal functions exerted an opposite effect. Further experiments demonstrated that H. pylori inhibited lysosomal acidification and the retrograde trafficking of mannose-6-phosphate receptors, both of which are known to positively regulate lysosomal function. We conclude that H. pylori subverts autophagy into a pro-survival mechanism through inhibition of lysosomal clearance of autophagosomes. Disruption of autophagosome formation offers a novel strategy to reduce H. pylori colonization in human stomachs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Therapeutic targeting of noncoding RNAs in hepatocellular carcinoma: Recent progress and future prospects

Due to the high mortality rate and unsatisfactory treatment options available, hepatocellular carcinoma (HCC) remains one of the most common malignancies and a leading cause of cancer-associated mortality. Novel therapeutic targets for HCC are urgently required. Advanced RNA sequencing technology enables the identification of considerable amounts of noncoding RNAs (ncRNAs), including small noncoding RNAs and long noncoding RNAs, which exhibit no protein-coding activities. In this respect, ncRNAs and their regulatory processes are important factors in liver tumorigenesis. The present review focuses on the characteristics and biological roles of ncRNAs in HCC. Potential therapeutic applications of ncRNAs in HCC are also evaluated.

How host regulation of Helicobacter pylori-induced gastritis protects against peptic ulcer disease and gastric cancer

The bacterial pathogen Helicobacter pylori is the etiological agent of a range of gastrointestinal pathologies including peptic ulcer disease and the major killer, gastric adenocarcinoma. Infection with this bacterium induces a chronic inflammatory response in the gastric mucosa (gastritis). It is this gastritis that, over decades, eventually drives the development of H. pylori-associated disease in some individuals. The majority of studies investigating H. pylori pathogenesis have focused on factors that promote disease development in infected individuals. However, an estimated 85% of those infected with H. pylori remain completely asymptomatic, despite the presence of pathogenic bacteria that drive a chronic gastritis that lasts many decades. This indicates the presence of highly effective regulatory processes in the host that, in most cases, keeps a check on inflammation and protect against disease. In this minireview we discuss such known host factors and how they prevent the development of H. pylori-associated pathologies.

Critical Role of Antimicrobial Peptide Cathelicidin for Controlling Helicobacter pylori Survival and Infection

The antimicrobial peptide cathelicidin is critical for protection against different kinds of microbial infection. This study sought to elucidate the protective action of cathelicidin against Helicobacter pylori infection and its associated gastritis. Exogenous cathelicidin was found to inhibit H. pylori growth, destroy the bacteria biofilm, and induce morphological alterations in H. pylori membrane. Additionally, knockdown of endogenous cathelicidin in human gastric epithelial HFE-145 cells markedly increased the intracellular survival of H. pylori. Consistently, cathelicidin knockout mice exhibited stronger H. pylori colonization, higher expression of proinflammatory cytokines IL-6, IL-1β, and ICAM1, and lower expression of the anti-inflammatory cytokine IL-10 in the gastric mucosa upon H. pylori infection. In wild-type mice, H. pylori infection also stimulated gastric epithelium-derived cathelicidin production. Importantly, pretreatment with bioengineered Lactococcus lactis that actively secretes cathelicidin significantly increased mucosal cathelicidin levels and reduced H. pylori infection and the associated inflammation. Moreover, cathelicidin strengthened the barrier function of gastric mucosa by stimulating mucus synthesis. Collectively, these findings indicate that cathelicidin plays a significant role as a potential natural antibiotic for H. pylori clearance and a therapeutic agent for chronic gastritis.

Changes in gastric microbiota induced by Helicobacter pylori infection and preventive effects of Lactobacillus plantarum ZDY 2013 against such infection

Helicobacter pylori is a gram-negative pathogen linked to gastric ulcers and stomach cancer. Gastric microbiota might play an essential role in the pathogenesis of these stomach diseases. In this study, we investigated the preventive effect of a probiotic candidate Lactobacillus plantarum ZDY 2013 as a protective agent against the gastric mucosal inflammation and alteration of gastric microbiota induced by H. pylori infection in a mouse model. Prior to infection, mice were pretreated with or without 400 µL of L. plantarum ZDY 2013 at a concentration of 10(9) cfu/mL per mouse. At 6 wk postinfection, gastric mucosal immune response and alteration in gastric microbiota mice were examined by quantitative real-time PCR and high-throughput 16S rRNA gene amplicon sequencing, respectively. The results showed that L. plantarum ZDY 2013 pretreatment prevented increase in inflammatory cytokines (e.g., IL-1β and IFN-γ) and inflammatory cell infiltration in gastric lamina propria induced by H. pylori infection. Weighted UniFrac principal coordinate analysis showed that L. plantarum ZDY 2013 pretreatment prevented the alteration in gastric microbiota post-H. pylori infection. Linear discriminant analysis coupled with effect size identified 22 bacterial taxa (e.g., Pasteurellaceae, Erysipelotrichaceae, Halomonadaceae, Helicobacteraceae, and Spirochaetaceae) that overgrew in the gastric microbiota of H. pylori-infected mice, and most of them belonged to the Proteobacteria phylum. Lactobacillus plantarum ZDY 2013 pretreatment prevented this alteration; only 6 taxa (e.g., Lachnospiraceae, Ruminococcaceae, and Clostridiaceae), mainly from the taxa of Firmicutes and Bacteroidetes, were dominant in the gastric microbiota of the L. plantarum ZDY 2013 pretreated mice. Administration of L. plantarum ZDY 2013 for 3 wk led to increase in several bacterial taxa (e.g., Rikenella, Staphylococcus, Bifidobacterium), although a nonsignificant alteration was found in the gastric microbiota. Overall, this study demonstrated that L. plantarum ZDY 2013 pretreatment played an important role in preventing gastric mucosal inflammation and gastric microbiota alteration induced by H. pylori infection, and the selective modulation in gastric microbiota posed by this intervention suggested that targeting gastric microbiota through oral administration of probiotics might be an alternative strategy to prevent H. pylori infection.

Antibiotic treatment for Helicobacter pylori: Is the end coming?

Infection with the Gram-negative pathogen Helicobacter pylori (H. pylori) has been associated with gastro-duodenal disease and the importance of H. pylori eradication is underscored by its designation as a group I carcinogen. The standard triple therapy consists of a proton pump inhibitor, amoxicillin and clarithromycin, although many other regimens are used, including quadruple, sequential and concomitant therapy regimens supplemented with metronidazole, clarithromycin and levofloxacin. Despite these efforts, current therapeutic regimens lack efficacy in eradication due to antibiotic resistance, drug compliance and antibiotic degradation by the acidic stomach environment. Antibiotic resistance to clarithromycin and metronidazole is particularly problematic and several approaches have been proposed to overcome this issue, such as complementary probiotic therapy with Lactobacillus. Other studies have identified novel molecules with an anti-H. pylori effect, as well as tailored therapy and nanotechnology as viable alternative eradication strategies. This review discusses current antibiotic therapy for H. pylori infections, limitations of this type of therapy and predicts the availability of newly developed therapies for H. pylori eradication.

Trans-species polymorphism at antimicrobial innate immunity cathelicidin genes of Atlantic cod and related species

Natural selection, the most important force in evolution, comes in three forms. Negative purifying selection removes deleterious variation and maintains adaptations. Positive directional selection fixes beneficial variants, producing new adaptations. Balancing selection maintains variation in a population. Important mechanisms of balancing selection include heterozygote advantage, frequency-dependent advantage of rarity, and local and fluctuating episodic selection. A rare pathogen gains an advantage because host defenses are predominantly effective against prevalent types. Similarly, a rare immune variant gives its host an advantage because the prevalent pathogens cannot escape the host's apostatic defense. Due to the stochastic nature of evolution, neutral variation may accumulate on genealogical branches, but trans-species polymorphisms are rare under neutrality and are strong evidence for balancing selection. Balanced polymorphism maintains diversity at the major histocompatibility complex (MHC) in vertebrates. The Atlantic cod is missing genes for both MHC-II and CD4, vital parts of the adaptive immune system. Nevertheless, cod are healthy in their ecological niche, maintaining large populations that support major commercial fisheries. Innate immunity is of interest from an evolutionary perspective, particularly in taxa lacking adaptive immunity. Here, we analyze extensive amino acid and nucleotide polymorphisms of the cathelicidin gene family in Atlantic cod and closely related taxa. There are three major clusters, Cath1, Cath2, and Cath3, that we consider to be paralogous genes. There is extensive nucleotide and amino acid allelic variation between and within clusters. The major feature of the results is that the variation clusters by alleles and not by species in phylogenetic trees and discriminant analysis of principal components. Variation within the three groups shows trans-species polymorphism that is older than speciation and that is suggestive of balancing selection maintaining the variation. Using Bayesian and likelihood methods positive and negative selection is evident at sites in the conserved part of the genes and, to a larger extent, in the active part which also shows episodic diversifying selection, further supporting the argument for balancing selection.

Cathelicidin suppresses colon cancer development by inhibition of cancer associated fibroblasts

BACKGROUND

Cathelicidin (LL-37 in humans and mCRAMP in mice) represents a family of endogenous antimicrobial and anti-inflammatory peptides. Cancer-associated fibroblasts can promote the proliferation of colon cancer cells and growth of colon cancer tumors.

METHODS

We examined the role of cathelicidin in the development of colon cancer, using subcutaneous human HT-29 colon-cancer-cell-derived tumor model in nude mice and azoxymethane- and dextran sulfate-mediated colon cancer model in C57BL/6 mice. We also determined the indirect antitumoral mechanism of cathelicidin via the inhibition of epithelial-mesenchymal transition (EMT) of colon cancer cells and fibroblast-supported colon cancer cell proliferation.

RESULTS

Intravenous administration of cathelicidin expressing adeno-associated virus significantly reduced the size of tumors, tumor-derived collagen expression, and tumor-derived fibroblast expression in HT-29-derived subcutaneous tumors in nude mice. Enema administration of the mouse cathelicidin peptide significantly reduced the size and number of colonic tumors in azoxymethane- and dextran sulfate-treated mice without inducing apoptosis in tumors and the adjacent normal colonic tissues. Cathelicidin inhibited the collagen expression and vimentin-positive fibroblast expression in colonic tumors. Cathelicidin did not directly affect HT-29 cell viability, but did significantly reduce tumor growth factor-β1-induced EMT of colon cancer cells. Media conditioned by the human colonic CCD-18Co fibroblasts promoted human colon cancer HT-29 cell proliferation. Cathelicidin pretreatment inhibited colon cancer cell proliferation mediated by media conditioned by human colonic CCD-18Co fibroblasts. Cathelicidin disrupted tubulin distribution in colonic fibroblasts. Disruption of tubulin in fibroblasts reduced fibroblast-supported colon cancer cell proliferation.

CONCLUSION

Cathelicidin effectively inhibits colon cancer development by interfering with EMT and fibroblast-supported colon cancer cell proliferation.

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.

Animal models of gastrointestinal inflammation and cancer

Inflammation and cancer are the two major disorders in the gastrointestinal tract. They are causally related in their pathogenesis. It is important to study animal models' causal relationship and, in particular, to discover new therapeutic agents for such diseases. There are several criteria for these models in order to make them useful in better understanding the etiology and treatment of the said diseases in humans. In this regard, animal models should be similar as possible to human diseases and also be easy to produce and reproducible and also economic to allow a continuous replication in different laboratories. In this review, we summarize the various animal models for inflammatory and cancerous disorders in the upper and lower gastrointestinal tract. Experimental approaches are as simple as by giving a single oral dose of alcohol or other noxious agents or by injections of multiple dosages of ulcer inducing agents or by parenteral administration or in drinking water of carcinogens or by modifying the genetic makeups of animals to produce relatively long-term pathological changes in particular organs. With these methods they could induce consistent inflammatory responses or tumorigenesis in the gastrointestinal mucosa. These animal models are widely used in laboratories in understanding the pathogenesis as well as the mechanisms of action for therapeutic agents in the treatment of gastrointestinal inflammation and cancer.

Inflammation, immunity, vaccines for Helicobacter pylori infection

Over the last decades, it has become evident that chronic infection by Helicobacter pylori is achieved by colonizing an almost exclusive niche and hiding from many of the host's cellular immune defense mechanisms. Although recent years have seen progress in our understanding of the innate and adaptive immune response against H. pylori, it is still uncertain how to promote the development of immunity with the final goal of a successful vaccine. Research published in the last year revealed an intriguing mutual regulation of innate response mechanisms of mucosal epithelial cells by the host and H. pylori, respectively. A further focus was put on the interaction between H. pylori and dendritic cells, with some emphasis on the inflammasome and the resulting T-cell responses. Moreover, the function of microRNAs in macrophages and gastric MALT lymphoma development has been studied in more detail. Several novel antigens and adjuvants have been tested as vaccination strategies, primarily in mice. In this review, we present a concise summary of advances in the area of inflammation, immunity, and vaccines during the last twelve months.

Cathelicidin a potential therapeutic peptide for gastrointestinal inflammation and cancer

Cathelicidins, are host defense peptides synthesized and stored in circulating leukocytes and numerous types of epithelial tissues in particular the gastrointestinal (GI) tract and skin. They have been known for their antimicrobial activities against a variety of microbes. Recently it was discovered that they have other significant biological functions and produce appealing pharmacological actions against inflammation and cancer in the GI tract through defined mechanisms. Experimental evidence shows that these actions could be tissue and disease specific and concentration dependent. This article reviews some of the physiological functions of cathelicidins and also their therapeutic potential in the treatment of inflammation and cancer and also the delivery system for this peptide as targeted therapy for various disorders in the GI tract both in animals and humans.