Lactoferrin and desferrioxamine are ineffective in the treatment of Helicobacter pylori infection and may enhance H. pylori growth and gastric inflammation in mice

Antimicrobial Effects of Lactoferrin against Helicobacter pylori Infection

Helicobacter (H.) pylori is the primary causative agent of various gastroduodenal diseases. H. pylori is an adapted microorganism that has evolved to survive in the acidic conditions of the human stomach, possessing a natural strategy for colonizing harsh environments. Despite the implementation of various eradication regimens worldwide, the eradication rate of H. pylori has decreased to less than 80% in recent years due to the emergence of antibiotic-resistant strains. This has posed a significant challenge in treating H. pylori infection, as antibiotic resistance and side effects have become increasingly problematic. Lactoferrin, a member of the transferrin family, is an iron-binding protein with antioxidant, antibacterial, antiviral, and anti-inflammatory properties that promote human health. The concentrations of lactoferrin in the gastric juice and mucosa significantly increase during H. pylori infection and are strongly correlated with the severity of gastric mucosal inflammation. Numerous researchers have studied the antimicrobial properties of lactoferrin both in vitro and in vivo. In addition, recent studies have investigated the addition of oral lactoferrin supplementation to H. pylori eradication therapy, even though monotherapy with lactoferrin does not eradicate the microorganism. In this article, we reviewed the survival strategy of H. pylori to evade the antimicrobial activity of human lactoferrin and explore the potential of lactoferrin in H. pylori eradication therapy.

Polyethylene microplastics cooperate with Helicobacter pylori to promote gastric injury and inflammation in mice

Microplastics provide stable habitats for the colonization and survival of pathogenic microorganisms, and cooperate with microorganisms to pose a potential threat to human health. In this study, polyethylene microplastics (PE-MPs) in artificial gastric juice time-dependently decomposed and broke into small-diameter PE-MP fragments that were more stable than those in an aqueous solution. Helicobacter pylori adhered to the surfaces of the PE-MPs to form a biofilm. The gastric tissues of mice treated with PE-MPs first and mixture of PE-MPs and H. pylori were positive for H. pylori infection in the 10th and 14th weeks after treatment, whereas those infected with H. pylori first and H. pylori alone were positive only in the 14th week after treatment. PE-MPs were visible in the gastric, intestinal, and liver tissues of mice treated with PE-MPs. The average diameter of the PE-MP fragments in the liver was greater than those of fragments that entered the gastric or intestinal tissues, and the average diameter of PE-MPs in the PE-MPs only-treated mice was significantly smaller than those of PE-MPs entering the intestinal tissues of the other groups. The infiltration of inflammatory cells was most serious in the mice treated with the mixture of PE-MPs and H. pylori, or with PE-MPs first and then H. pylori. Of all the groups, the gastric organ index and MPO, IL6, and TNF-α levels were highest in the mice treated with the mixture of PE-MPs and H. pylori. These results indicate that the interaction between PE-MPs and H. pylori contributed to the rapid bacterial colonization of gastric mucosal epithelial cells, improved the efficiency of PE-MP entry into tissues, and promoted gastric injury and inflammation in mice. These findings suggest that microplastics may provide a stable habitat for H. pylori, and act synergistically with H. pylori to pose a potential threat to human health.

The Innate Immune Glycoprotein Lactoferrin Represses the Helicobacter pylori cag Type IV Secretion System

Chronic infection with Helicobacter pylori increases risk of gastric diseases including gastric cancer. Despite development of a robust immune response, H. pylori persists in the gastric niche. Progression of gastric inflammation to serious disease outcomes is associated with infection with H. pylori strains which encode the cag Type IV Secretion System (cag T4SS). The cag T4SS is responsible for translocating the oncogenic protein CagA into host cells and inducing pro-inflammatory and carcinogenic signaling cascades. Our previous work demonstrated that nutrient iron modulates the activity of the T4SS and biogenesis of T4SS pili. In response to H. pylori infection, the host produces a variety of antimicrobial molecules, including the iron-binding glycoprotein, lactoferrin. Our work shows that apo-lactoferrin exerts antimicrobial activity against H. pylori under iron-limited conditions, while holo-lactoferrin enhances bacterial growth. Culturing H. pylori in the presence of holo-lactoferrin prior to co-culture with gastric epithelial cells, results in repression of the cag T4SS activity. Concomitantly, a decrease in biogenesis of cag T4SS pili at the host-pathogen interface was observed under these culture conditions by high-resolution electron microscopy analyses. Taken together, these results indicate that acquisition of alternate sources of nutrient iron plays a role in regulating the pro-inflammatory activity of a bacterial secretion system and present novel therapeutic targets for the treatment of H. pylori-related disease.

Lactoferrin in the Prevention and Treatment of Intestinal Inflammatory Pathologies Associated with Colorectal Cancer Development

The connection between inflammation and cancer is well-established and supported by genetic, pharmacological and epidemiological data. The inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis, have been described as important promoters for colorectal cancer development. Risk factors include environmental and food-borne mutagens, dysbalance of intestinal microbiome composition and chronic intestinal inflammation, with loss of intestinal epithelial barrier and enhanced cell proliferation rate. Therapies aimed at shutting down mucosal inflammatory response represent the foundation for IBDs treatment. However, when applied for long periods, they can alter the immune system and promote microbiome dysbiosis and carcinogenesis. Therefore, it is imperative to find new safe substances acting as both potent anti-inflammatory and anti-pathogen agents. Lactoferrin (Lf), an iron-binding glycoprotein essential in innate immunity, is generally recognized as safe and used as food supplement due to its multifunctionality. Lf possesses a wide range of immunomodulatory and anti-inflammatory properties against different aseptic and septic inflammatory pathologies, including IBDs. Moreover, Lf exerts anti-adhesive, anti-invasive and anti-survival activities against several microbial pathogens that colonize intestinal mucosa of IBDs patients. This review focuses on those activities of Lf potentially useful for the prevention/treatment of intestinal inflammatory pathologies associated with colorectal cancer development.

Lactoferrin: Balancing Ups and Downs of Inflammation Due to Microbial Infections

Lactoferrin (Lf) is a glycoprotein of the primary innate immune-defense system of mammals present in milk and other mucosal secretions. This protein of the transferrin family has broad antimicrobial properties by depriving pathogens from iron, or disrupting their plasma membranes through its highly cationic charge. Noteworthy, Lf also exhibits immunomodulatory activities performing up- and down-regulation of innate and adaptive immune cells, contributing to the homeostasis in mucosal surfaces exposed to myriad of microbial agents, such as the gastrointestinal and respiratory tracts. Although the inflammatory process is essential for the control of invasive infectious agents, the development of an exacerbated or chronic inflammation results in tissue damage with life-threatening consequences. In this review, we highlight recent findings in in vitro and in vivo models of the gut, lung, oral cavity, mammary gland, and liver infections that provide experimental evidence supporting the therapeutic role of human and bovine Lf in promoting some parameters of inflammation and protecting against the deleterious effects of bacterial, viral, fungal and protozoan-associated inflammation. Thus, this new knowledge of Lf immunomodulation paves the way to more effective design of treatments that include native or synthetic Lf derivatives, which may be useful to reduce immune-mediated tissue damage in infectious diseases.

Efficacy of fermented milk and whey proteins in Helicobacter pylori eradication: A review

Helicobacter pylori (H. pylori) eradication is considered a necessary step in the management of peptic ulcer disease, chronic gastritis, gastric adenocarcinoma and mucosa associated lymphoid tissue lymphoma. Standard triple therapy eradication regimens are inconvenient and achieve unpredictable and often poor results. Eradication rates are decreasing over time with increase in antibiotic resistance. Fermented milk and several of its component whey proteins have emerged as candidates for complementary therapy. In this context the current review seeks to summarize the current evidence available on their role in H. pylori eradication. Pertinent narrative/systematic reviews, clinical trials and laboratory studies on individual components including fermented milk, yogurt, whey proteins, lactoferrin, α-lactalbumin (α-LA), glycomacropeptide and immunoglobulin were comprehensively searched and retrieved from Medline, Embase, Scopus, Cochrane Controlled Trials Register and abstracts/proceedings of conferences up to May 2013. A preponderance of the evidence available on fermented milk-based probiotic preparations and bovine lactoferrin suggests a beneficial effect in Helicobacter eradication. Evidence for α-LA and immunoglobulins is promising while that for glycomacropeptide is preliminary and requires substantiation. The magnitude of the potential benefit documented so far is small and the precise clinical settings are ill defined. This restricts the potential use of this group as a complementary therapy in a nutraceutical setting hinging on better patient acceptability/compliance. Further work is necessary to identify the optimal substrate, fermentation process, dose and the ideal clinical setting (prevention/treatment, first line therapy/recurrence, symptomatic/asymptomatic, gastritis/ulcer diseases etc.). The potential of this group in high antibiotic resistance or treatment failure settings presents interesting possibilities and deserves further exploration.

Evaluation of the anti-adhesive effect of milk fat globule membrane glycoproteins on Helicobacter pylori in the human NCI-N87 cell line and C57BL/6 mouse model

BACKGROUND

 The interest in non-antibiotic therapies for Helicobacter pylori infections in man has considerably grown because increasing numbers of antibiotic-resistant strains are being reported. Intervention at the stage of bacterial attachment to the gastric mucosa could be an approach to improve the control/eradication rate of this infection.

MATERIALS AND METHODS

 Fractions of purified milk fat globule membrane glycoproteins were tested in vitro for their cytotoxic and direct antibacterial effect. The anti-adhesive effect on H. pylori was determined first in a cell model using the mucus-producing gastric epithelial cell line NCI-N87 and next in the C57BL/6 mouse model after dosing at 400 mg/kg protein once or twice daily from day -2 to day 4 post-infection. Bacterial loads were determined by using quantitative real-time PCR and the standard plate count method.

RESULTS

 The milk fat globule membrane fractions did not show in vitro cytotoxicity, and a marginal antibacterial effect was demonstrated for defatted milk fat globule membrane at 256 μg/mL. In the anti-adhesion assay, the results varied from 56.0 ± 5.3% inhibition for 0.3% crude milk fat globule membrane to 79.3 ± 3.5% for defatted milk fat globule membrane. Quite surprisingly, in vivo administration of the same milk fat globule membrane fractions did not confirm the anti-adhesive effects and even caused an increase in bacterial load in the stomach.

CONCLUSIONS

 The promising anti-adhesion in vitro results could not be confirmed in the mouse model, even after the highest attainable exposure. It is concluded that raw or defatted milk fat globule membrane fractions do not have any prophylactic or therapeutic potential against Helicobacter infection.

Human lactoferrin increases Helicobacter pylori internalisation into AGS cells

Helicobacter pylori has high global infection rates and can cause other undesirable clinical manifestations such as duodenal ulcer (DU) and gastric cancer (GC). Frequencies of re-infection after therapeutic clearance and rates of DU versus GC vary geographically and differ markedly between developed and developing countries, which suggests additional factors may be involved. The possibility that, in vivo, lactoferrin (Lf) may play a subtle role in modulating micronutrient availability or bacterial internalisation with implications for disease etiology is considered. Lf is an iron binding protein produced in mammals that has antimicrobial and immunomodulatory properties. Some bacteria that regularly colonise mammalian hosts have adapted to living in high Lf environments and we investigated if this included the gastric pathogen H. pylori. We found that H. pylori was able to use iron from fully iron-saturated human Lf (hLf) whereas partially iron-saturated hLf (apo) did not increase H. pylori growth. Instead, apo-hLf increased adherence to and internalisation of bacteria into cultured epithelial cells. By increasing internalisation, we speculate that apo-human lactoferrin may contribute to H. pylori's ability to persistence in the human stomach, an observation that potentially has implications for the risk of H. pylori-associated disease.

Bovine antibody-based oral immunotherapy for reduction of intragastric Helicobacter pylori colonization: a randomized clinical trial

BACKGROUND

Antibiotic-based regimens are frequently used for the treatment of Helicobacter pylori infection. These regimens fail to eradicate H pylori in 15% to 40% of patients, primarily due to antimicrobial resistance and insufficient patient compliance. Effective prevention and eradication of H pylori by passive immunization with orally administered bovine antibodies has been demonstrated in animal studies, and may serve as an alternative therapy in humans.

OBJECTIVE

To study the efficacy and safety of orally administered bovine anti-H pylori antibodies for the reduction of intragastric bacterial load and eradication of H pylori in humans.

METHODS

Dairy cows were immunized against H pylori. After confirmation of the presence of anti-H pylori antibodies in the milk, the milk was subsequently processed into a whey protein concentrate (WPC). In a prospective, double-blind, placebo-controlled randomized clinical trial, H pylori-infected subjects were randomly assigned to treatment with the WPC preparation or placebo. Study medication was continued for 28 days; subjects were followed-up for 56 days.

RESULTS

Of the 30 subjects included, 27 completed the protocol. Of these 27 evaluable subjects, 14 were treated with WPC and 13 with placebo. There was no significant difference in urea breath test decrease between the WPC- and placebo-treated group (P=0.75). H pylori-associated gastritis and density were not significantly reduced in either group after treatment (P>0.05 for all).

CONCLUSION

Bovine antibody-based oral immunotherapy appears to be safe, but does not significantly reduce intragastric density in humans. Further studies are needed to determine whether WPC treatment has additional value to conventional antibiotic treatment for H pylori.

Unique host iron utilization mechanisms of Helicobacter pylori revealed with iron-deficient chemically defined media

Helicobacter pylori chronically infects the gastric mucosa, where it can be found free in mucus, attached to cells, and intracellularly. H. pylori requires iron for growth, but the sources of iron used in vivo are unclear. In previous studies, the inability to culture H. pylori without serum made it difficult to determine which host iron sources might be used by H. pylori. Using iron-deficient, chemically defined medium, we determined that H. pylori can bind and extract iron from hemoglobin, transferrin, and lactoferrin. H. pylori can use both bovine and human versions of both lactoferrin and transferrin, contrary to previous reports. Unlike other pathogens, H. pylori preferentially binds the iron-free forms of transferrin and lactoferrin, which limits its ability to extract iron from normal serum, which is not iron saturated. This novel strategy may have evolved to permit limited growth in host tissue during persistent colonization while excessive injury or iron depletion is prevented.