Characterization of Chicken IgY Specific to Clostridium difficile R20291 Spores and the Effect of Oral Administration in Mouse Models of Initiation and Recurrent Disease

Understanding host immune responses in Clostridioides difficile infection: Implications for pathogenesis and immunotherapy

Clostridioides difficile (C. difficile) is the predominant causative agent of nosocomial diarrhea worldwide. Infection with C. difficile occurs due to the secretion of large glycosylating toxin proteins, which can lead to toxic megacolon or mortality in susceptible hosts. A critical aspect of C. difficile's biology is its ability to persist asymptomatically within the human host. Individuals harboring asymptomatic colonization or experiencing a single episode of C. difficile infection (CDI) without recurrence exhibit heightened immune responses compared to symptomatic counterparts. The significance of these immune responses cannot be overstated, as they play critical roles in the development, progression, prognosis, and outcomes of CDI. Nonetheless, our current comprehension of the immune responses implicated in CDI remains limited. Therefore, further investigation is imperative to elucidate their underlying mechanisms. This review explores recent advancements in comprehending CDI pathogenesis and how the host immune system response influences disease progression and severity, aiming to enhance our capacity to develop immunotherapy-based treatments for CDI.

Production and purification of Clostridium perfringens type C beta-toxin and IgG and IgY antitoxins

OBJECTIVES

This study aimed to produce and purify Clostridium perfringens type C beta-toxin, sheep anti-beta toxin immunoglobulin G (IgG) and chicken immunoglobulin Y (IgY).

METHODS

Two methods were used for beta-toxin purification: single-step metal affinity chromatography (MAC) using zinc as a chelator and ion exchange chromatography (IEX). The purified and inactivated beta-toxoids were then administered to sheep and chickens in order to produce IgG and IgY.

RESULTS

All assays using the IEX failed. In contrast, MAC purified more than 21 mg of toxin per run in a single-step protocol. The purified and inactivated beta-toxoids were then administered to sheep and chickens, and IgG and IgY were purified with a high yield, medium antibody titer of 50 IU/mL, and high avidity (73.2 %).

CONCLUSIONS

C. perfringens type C beta-toxin and sheep or chicken anti-beta toxin IgG and IgY antibodies were successfully produced and purified using a simple protocol. This protocol can be used for the production of components used in the diagnosis and research of necrotic enteritis caused by C. perfringens type C, as well as for the evaluation of existing vaccines and the development of new preventive methods against this disease.

IgYs: on her majesty's secret service

There has been an increasing interest in using Immunoglobulin Y (IgY) antibodies as an alternative to "classical" antimicrobials. Unlike traditional antibiotics, they can be utilized on a continual basis without leading to the development of resistance. The veterinary IgY antibody market is growing because of the demand for minimal antibiotic use in animal production. IgY antibodies are not as strong as antibiotics for treating infections, but they work well as preventative agents and are natural, nontoxic, and easy to produce. They can be administered orally and are well tolerated, even by young animals. Unlike antibiotics, oral IgY supplements support the microbiome that plays a vital role in maintaining overall health, including immune system function. IgY formulations can be delivered as egg yolk powder and do not require extensive purification. Lipids in IgY supplements improve antibody stability in the digestive tract. Given this, using IgY antibodies as an alternative to antimicrobials has garnered interest. In this review, we will examine their antibacterial potential.

Egg Yolk Antibody for Passive Immunization: Status, Challenges, and Prospects

The immunoglobulin Y (IgY) derived from hyperimmune egg yolk is a promising passive immune agent to combat microbial infections in humans and livestock. Numerous studies have been performed to develop specific egg yolk IgY for pathogen control, but with limited success. To date, the efficacy of commercial IgY products, which are all delivered through an oral route, has not been approved or endorsed by any regulatory authorities. Several challenging issues of the IgY-based passive immunization, which were not fully recognized and holistically discussed in previous publications, have impeded the development of effective egg yolk IgY products for humans and animals. This review summarizes major challenges of this technology, including in vivo stability, purification, heterologous immunogenicity, and repertoire diversity of egg yolk IgY. To tackle these challenges, potential solutions, such as encapsulation technologies to stabilize IgY, are discussed. Exploration of this technology to combat the COVID-19 pandemic is also updated in this review.

Redistribution of the Novel Clostridioides difficile Spore Adherence Receptor E-Cadherin by TcdA and TcdB Increases Spore Binding to Adherens Junctions

Clostridioides difficile causes antibiotic-associated diseases in humans, ranging from mild diarrhea to severe pseudomembranous colitis and death. A major clinical challenge is the prevention of disease recurrence, which affects nearly ~20 to 30% of the patients with a primary C. difficile infection (CDI). During CDI, C. difficile forms metabolically dormant spores that are essential for recurrence of CDI (R-CDI). In prior studies, we have shown that C. difficile spores interact with intestinal epithelial cells (IECs), which contribute to R-CDI. However, this interaction remains poorly understood. Here, we provide evidence that C. difficile spores interact with E-cadherin, contributing to spore adherence and internalization into IECs. C. difficile toxins TcdA and TcdB lead to adherens junctions opening and increase spore adherence to IECs. Confocal micrographs demonstrate that C. difficile spores associate with accessible E-cadherin; spore-E-cadherin association increases upon TcdA and TcdB intoxication. The presence of anti-E-cadherin antibodies decreased spore adherence and entry into IECs. By enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and immunogold labeling, we observed that E-cadherin binds to C. difficile spores, specifically to the hairlike projections of the spore, reducing spore adherence to IECs. Overall, these results expand our knowledge of how C. difficile spores bind to IECs by providing evidence that E-cadherin acts as a spore adherence receptor to IECs and by revealing how toxin-mediated damage affects spore interactions with IECs.

Synbiotic-IgY Therapy Modulates the Mucosal Microbiome and Inflammatory Indices in Dogs with Chronic Inflammatory Enteropathy: A Randomized, Double-Blind, Placebo-Controlled Study

Chronic inflammatory enteropathy (CE) is a common cause of persistent gastrointestinal signs and intestinal inflammation in dogs. Since evidence links dysbiosis to mucosal inflammation, probiotics, prebiotics, or their combination (synbiotics) may reduce intestinal inflammation and ameliorate dysbiosis in affected dogs. This study's aim was to investigate the effects of the synbiotic-IgY supplement on clinical signs, inflammatory indices, and mucosal microbiota in dogs with CE. Dogs with CE were enrolled in a randomized prospective trial. Twenty-four client-owned dogs were fed a hydrolyzed diet and administered supplement or placebo (diet) for 6 weeks. Dogs were evaluated at diagnosis and 2- and 6-week post-treatment. Outcome measures included clinical activity, endoscopic and histologic scores, inflammatory markers (fecal calprotectin, C-reactive protein), and composition of the mucosal microbiota via FISH. Eleven supplement- and nine placebo-treated dogs completed the trial. After 6 weeks of therapy, clinical activity and endoscopic scores decreased in both groups. Compared to placebo-treated dogs, dogs administered supplement showed decreased calprotectin at 2-week post-treatment, decreased CRP at 2- and 6-week post-treatment increased mucosal Clostridia and Bacteroides and decreased Enterobacteriaceae in colonic biopsies at trial completion. Results suggest a beneficial effect of diet and supplements on host responses and mucosal microbiota in dogs with CE.

Polymeric Nanohybrids Engineered by Chitosan Nanoparticles and Antimicrobial Peptides as Novel Antimicrobials in Food Biopreservatives: Risk Assessment and Anti-Foodborne Pathogen Escherichia coli O157:H7 Infection by Immune Regulation

Polymeric nanomaterials (APs) are gaining attention as promising clinical antimicrobials with rapidly increasing antibiotic resistance. Infections by zoonotic enterohemorrhagic Escherichia coli are a severe global threat to public health. Chitosan nanoparticles-microcin J25 (CNM), a class of APs engineered by bioactive peptides and chitosan nanoparticles, can be used as a novel antimicrobial agent against bacterial infections. However, the risk assessment of CNM on animal health or its potential immune modulation to treat serotype E. coli O157:H7 infection impacts in vivo are not well understood. Herein, our findings in mouse models uncovered that oral administration of low levels of CNM significantly increased the body weight and made beneficial effects on the lifespan or clinical signs, accompanied by a significant improvement in gut health, including enhancing the intestinal barrier, immune modulation, and changes in gut microbiota compositions or metabolites. However, high concentrations of CNM induced serious adverse effects, negatively improving intestinal health targets. Anti-infective results proved that oral 0.1% CNM enhances host defense against E. coli O157:H7 infection by improving immune functions and modulating the Th1/Th2 balance. In summary, these findings uncover an instrumental link between the dosage and toxicity risk, suggesting that APs need to be comprehensively assessed for risk before application as safe and reliable food preservatives or therapeutic agents. In addition, CNM as a promising AP may markedly enhance host immunity and therapeutic effects by oral administration.

Chicken IgY reduces the risk of Pseudomonas aeruginosa urinary tract infections in a murine model

Introduction

Urinary tract infections (UTIs) with Pseudomonas aeruginosa are a severe problem in disposed patients in modern healthcare. Pseudomonas aeruginosa establishes recalcitrant biofilm infections and can develop antibiotic resistance. Gargling with avian egg yolk anti-Pseudomonas antibodies (IgY) has shown clinical effect in preventing onset of chronic P. aeruginosa lung infections in patients with cystic fibrosis (CF). Therefore, we speculated whether passive intravesically administered IgY immunotherapy could be a novel strategy against P. aeruginosa UTIs.

Aim

To evaluate if prophylactic repurposing of anti-Pseudomonas IgY can prevent UTIs with P. aeruginosa in a UTI mouse model.

Materials and methods

In vitro, P. aeruginosa (PAO1 and PAO3) was mixed with increasing concentrations of specific anti-Pseudomonas IgY (sIgY) or non-specific control IgY (cIgY) and/or freshly isolated human neutrophils. Bacterial growth was evaluated by the optical density at 600 nm. In vivo, via a temporary transurethral catheter, 10-week-old female Balb/c mice were intravesically infected with 50 ml of a bacterial suspension and sIgY, cIgY, or isotonic NaCl. IgY and NaCl were either co-instilled with the bacteria, or instilled prophylactically, 30 min prior to infection. The animals were euthanized 20 h after infection. Vesical bacteriology was quantified, and cytokine expression in the bladder homogenate was measured by multiplex cytokine assay.

Results

In vitro, sIgY concentrations above 2.5% reduced bacterial growth in a dose-dependent manner. In vivo, a UTI lasting for minimum 7 days was established by installing 5 × 106 colony-forming units (CFU) of P. aeruginosa PAO1. sIgY reduced vesical bacterial load if co-installed with P. aeruginosa PAO1. Prophylactic sIgY and cIgY reduced bacterial load when compared to isotonic NaCl. CXCL2 and G-CSF were both increased in infected bladders compared to non-infected controls which had non-detectable levels. Co-installation of sIgY and bacteria nearly completely inhibited the inflammatory response. However, the cytokine levels in the bladder did not change after prophylactic administration of sIgY or cIgY.

Conclusion

Prophylactic sIgY significantly reduces the amount of bacteria in the bladder in a mouse model of P. aeruginosa cystitis and may serve as a novel non-antibiotic strategy in preventing P. aeruginosa UTIs.

Scientometric analysis and perspective of IgY technology study

Egg yolk immunoglobulin (IgY) is a class of antibody that is produced in birds against pathogens. Therefore, hyperimmunization of birds can produce a specific antibody in the egg against target antigen for a wide range of applications in diagnostic, prophylactic or treatment in human and veterinary medicine which is known today as IgY technology. Until now, the number of articles, patents and clinical studies on IgY technology has increased significantly. Hence, there is a fact that scientometric studies are needed to gain a deeper understanding of the research for the commercialization of IgY technology. Until now, no scientometric research has been directed toward IgY technology. In view of this, we conducted scientometric analysis in the WoS database. A total of 1,029 IgY-related papers were obtained including 981 journal articles and 48 reviews. The visualization of this literature showed an increasing trend in the number of IgY-related publications over the 4 decades, especially after 2008 to 2021. China, the United States, Canada, Japan, and Germany had the largest number of publications, with 220, 148, 91, 76, and 72, respectively. Among all the research institutions, Dalian University of Technology, Alberta University and Northwest Agriculture and Forestry University published the most of the articles, respectively. Among authors, Dr. Xiaoying Zhang had the highest number of publications with 21. The top most cited publications were from Dr. da Silva with 38 citations. Keywords co-occurrence network analysis showed that the correlation between different keywords is large, especially IgY, antibodies and immunoglobulin which is consistent with the rapid increase in the number of publications. Finally, through this data analysis, we hope that our result could help IgY technology to more maturity toward industrialization and commercialization.

Using a ligate intestinal loop mouse model to investigate Clostridioides difficile adherence to the intestinal mucosa in aged mice

Interaction of Clostridioides difficile spores with the intestinal mucosa contributes to the persistence and recurrence of the infection. Advanced age is one of the main risk factors for C. difficile infection and recurrence of the disease. However, interaction of C. difficile spores with the intestinal mucosa during aging has not been evaluated. In the present work, using intestinal ligated loop technique in a mouse model, we analyzed C. difficile spore adherence and internalization to the ileum and colonic mucosa during aging. Additionally, we provide visual documentation of the critical steps of the procedure. Consequently, our data suggest that spore internalization in the ileum and colonic mucosa is higher in elderly mice rather than adults or young mice. Also, our data suggest that spore adherence to the ileum and colonic mucosa decreases with aging.

Learning from Nature: Bacterial Spores as a Target for Current Technologies in Medicine (Review)

The capability of some representatives of Clostridium spp. and Bacillus spp. genera to form spores in extreme external conditions long ago became a subject of medico-biological investigations. Bacterial spores represent dormant cellular forms of gram-positive bacteria possessing a high potential of stability and the capability to endure extreme conditions of their habitat. Owing to these properties, bacterial spores are recognized as the most stable systems on the planet, and spore-forming microorganisms became widely spread in various ecosystems.

Spore-forming bacteria have been attracted increased interest for years due to their epidemiological danger. Bacterial spores may be in the quiescent state for dozens or hundreds of years but after they appear in the favorable conditions of a human or animal organism, they turn into vegetative forms causing an infectious process. The greatest threat among the pathogenic spore-forming bacteria is posed by the causative agents of anthrax (B. anthracis), food toxicoinfection (B. cereus), pseudomembranous colitis (C. difficile), botulism (C. botulinum), gas gangrene (C. perfringens).

For the effective prevention of severe infectious diseases first of all it is necessary to study the molecular structure of bacterial spores and the biochemical mechanisms of sporulation and to develop innovative methods of detection and disinfection of dormant cells. There is another side of the problem: the necessity to investigate exo- and endospores from the standpoint of obtaining similar artificially synthesized models in order to use them in the latest medical technologies for the development of thermostable vaccines, delivery of biologically active substances to the tissues and intracellular structures. In recent years, bacterial spores have become an interesting object for the exploration from the point of view of a new paradigm of unicellular microbiology in order to study microbial heterogeneity by means of the modern analytical tools.

Tecnología IgY: Estrategia en el tratamiento de enfermedades infecciosas humanas

La aparición de microorganismos resistentes a antibióticos, el descubrimiento de nuevos agentes patógenos con potencial pandémico y el aumento de una población inmunocomprometida han dejado casi obsoleta la terapia antimicrobiana, terapia comúnmente usada para tratar enfermedades infecciosas. Por otro lado, las investigaciones acerca del uso del anticuerpo IgY para desarrollar inmunidad pasiva han demostrado el potencial que tiene la tecnología IgY para tratar enfermedades infecciosas víricas y bacterianas. Donde los anticuerpos IgY de aves se destacan por su alta especificidad, rendimiento y escalabilidad de producción a menor costo, con relación a los anticuerpos IgG de mamíferos. El objetivo de esta revisión es determinar la importancia del uso de los anticuerpos IgY como tratamiento terapéutico y profiláctico frente a los patógenos causantes de infecciones virales y bacterianas en humanos, mediante la recopilación de ensayos clínicos, productos comerciales y patentes registradas en el período de 2010-2021. Finalmente, con este estudio se estableció que la tecnología IgY es una herramienta biotecnológica versátil y eficaz para tratar y prevenir enfermedades infecciosas, al reducir los síntomas y la carga del patógeno.

Inhibition of spores to prevent the recurrence of Clostridioides difficile infection - A possibility or an improbability?

Clostridioides difficile is one of the most common nosocomial gastrointestinal pathogens, and recurrence is a problematic issue because approximately 20-30% of patients experience at least one episode of recurrence, even after treatment with a therapeutic drug of choice for C. difficile infection (CDI), such as vancomycin. CDI recurrence has a multifactorial complex mechanism, in which gut microbiota disruption coincident with viable C. difficile spores, is considered the most important factor. The effectiveness of an anti-C. difficile antimicrobial agent against CDI cannot guarantee its inhibitory effect on C. difficile spores and vice versa. However, an antimicrobial agent, such as fidaxomicin, which has a good inhibitory effect on both C. difficile vegetative cells and spores is assumed to not only treat CDI but also prevent its recurrence. Prolonged adherence to the exosporium has been proposed as a possible mechanism of inhibiting spores, and as a result, redesigning anti-C. difficile antimicrobial agents with the ability to adhere to the exosporium may provide another pathway for the development of anti-C. difficile spore agents. For example, vancomycin lacks an inhibitory effect against C. difficile spores, but a vancomycin-loaded spore-targeting iron oxide nanoparticle that selectively binds to C. difficile spores has been developed to successfully delay spore germination. Some new antimicrobial agents in phase II clinical trials, including cadazolid and ridinilazole, have shown exceptional anti-C. difficile and spore-inhibiting effects that can be expected to not only treat CDI but also prevent its recurrence in the future.

Immunoglobulin Y for Potential Diagnostic and Therapeutic Applications in Infectious Diseases

Antiviral, antibacterial, and antiparasitic drugs and vaccines are essential to maintaining the health of humans and animals. Yet, their production can be slow and expensive, and efficacy lost once pathogens mount resistance. Chicken immunoglobulin Y (IgY) is a highly conserved homolog of human immunoglobulin G (IgG) that has shown benefits and a favorable safety profile, primarily in animal models of human infectious diseases. IgY is fast-acting, easy to produce, and low cost. IgY antibodies can readily be generated in large quantities with minimal environmental harm or infrastructure investment by using egg-laying hens. We summarize a variety of IgY uses, focusing on their potential for the detection, prevention, and treatment of human and animal infections.

Chicken Egg Yolk Antibody (IgY) Protects Mice Against Enterotoxigenic Escherichia coli Infection Through Improving Intestinal Health and Immune Response

Chicken egg yolk antibody (IgY), considered as a potential substitute for antibiotics, has been used for preventing pathogens infection in food, human and animals. This study investigated effects of IgY on growth, adhesion inhibitory and morphology of enterotoxigenic Escherichia coli (ETEC) K88 in vitro, and evaluated the protective effects of IgY on intestinal health and immune response of mice infected with ETEC in vivo. Sixty pathogen-free C57BL/6J (4-6 weeks of age) mice were divided into six treatments: control (neither IgY nor ETEC infection), ETEC infection, ETEC-infected mice treated with 250 μL of high-dose (32 mg/mL), medium-dose (16 mg/mL) or low-dose (8 mg/mL) anti-ETEC IgY, or ETEC-infected mice treated with 250 μL of non-specific IgY (16 mg/mL). Anti-ETEC IgY inhibited ETEC growth, reduced adherence of ETEC to intestinal epithelial cells J2 and damaged the morphology and integrity of ETEC cell. Oral administration of anti-ETEC IgY effectively ameliorated ETEC-induced clinical signs, reduced ETEC colonization and intestinal permeability, alleviated inflammatory response through reducing the production and expression of proinflammatory cytokines, improved intestinal morphology, and inhibited excessive activation of the mucosal immune response of challenged mice. The overall protective effects of high-dose and medium-dose anti-ETEC IgY against ETEC infection were more effective. These results suggest that anti-ETEC IgY may function as a promising novel prophylactic agent against enteric pathogens infection.

Entry of spores into intestinal epithelial cells contributes to recurrence of Clostridioides difficile infection

Clostridioides difficile spores produced during infection are important for the recurrence of the disease. Here, we show that C. difficile spores gain entry into the intestinal mucosa via pathways dependent on host fibronectin-α5β1 and vitronectin-αvβ1. The exosporium protein BclA3, on the spore surface, is required for both entry pathways. Deletion of the bclA3 gene in C. difficile, or pharmacological inhibition of endocytosis using nystatin, leads to reduced entry into the intestinal mucosa and reduced recurrence of the disease in a mouse model. Our findings indicate that C. difficile spore entry into the intestinal barrier can contribute to spore persistence and infection recurrence, and suggest potential avenues for new therapies.

A Novel, Orally Delivered Antibody Therapy and Its Potential to Prevent Clostridioides difficile Infection in Pre-clinical Models

Clostridioides difficile infection (CDI) is a toxin-mediated infection in the gut and a major burden on healthcare facilities worldwide. We rationalized that it would be beneficial to design an antibody therapy that is delivered to, and is active at the site of toxin production, rather than neutralizing the circulating and luminal toxins after significant damage of the layers of the intestines has occurred. Here we describe a highly potent therapeutic, OraCAb, with high antibody titers and a formulation that protects the antibodies from digestion/inactivation in the gastrointestinal tract. The potential of OraCAb to prevent CDI in an in vivo hamster model and an in vitro human colon model was assessed. In the hamster model we optimized the ratio of the antibodies against each of the toxins produced by C. difficile (Toxins A and B). The concentration of immunoglobulins that is effective in a hamster model of CDI was determined. A highly significant difference in animal survival for those given an optimized OraCAb formulation versus an untreated control group was observed. This is the first study testing the effect of oral antibodies for treatment of CDI in an in vitro gut model seeded with a human fecal inoculum. Treatment with OraCAb successfully neutralized toxin production and did not interfere with the colonic microbiota in this model. Also, treatment with a combination of vancomycin and OraCAb prevented simulated CDI recurrence, unlike vancomycin therapy alone. These data demonstrate the efficacy of OraCAb formulation for the treatment of CDI in pre-clinical models.

Lasso Peptide Microcin J25 Effectively Enhances Gut Barrier Function and Modulates Inflammatory Response in an Enterotoxigenic Escherichia coli-Challenged Mouse Model

Bacterial resistance leads to severe public health and safety issues worldwide. Alternatives to antibiotics are currently needed. A promising lasso peptide, microcin J25 (MccJ25), is considered to be the best potential substitute for antibiotics to treat pathogen infection, including enterotoxigenic Escherichia coli (ETEC). This study evaluated the efficacy of MccJ25 in the prevention of ETEC infection. Forty-five female BALB/c mice of clean grade (aged seven weeks, approximately 16.15 g) were randomly divided into three experimental groups as follows: (i) control group (uninfected); (ii) ETEC infection group; (iii) MccJ25 + ETEC group. Fifteen mice per group in five cages, three mice/cage. MccJ25 conferred effective protection against ETEC-induced body weight loss, decrease in rectal temperature and increase in diarrhea scores in mice. Moreover, in ETEC-challenged mice model, MccJ25 significantly improved intestinal morphology, decreased intestinal histopathological scores and attenuated intestinal inflammation by decreasing proinflammatory cytokines and intestinal permeability, including reducing serum diamine oxidase and D-lactate levels. MccJ25 enhanced epithelial barrier function by increasing occludin expression in the colon and claudin-1 expression in the jejunum, ultimately improving intestinal health of host. MccJ25 was further found to alleviate gut inflammatory responses by decreasing inflammatory cytokine production and expression via the activation of the mitogen-activated protein kinase and nuclear factor κB signaling pathways. Taken together, the results indicated that MccJ25 protects against ETEC-induced intestinal injury and intestinal inflammatory responses, suggesting the potential application of MccJ25 as an excellent antimicrobial or anti-inflammation agent against pathogen infections.

Can Immunization of Hens Provide Oral-Based Therapeutics against COVID-19?

In the current worldwide pandemic situation caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and the newest coronavirus disease (COVID-19), therapeutics and prophylactics are urgently needed for a large population. Some of the prophylaxis strategies are based on the development of antibodies targeting viral proteins. IgY antibodies are a type of immunoglobulin present in birds, amphibians, and reptiles. They are usually obtained from egg yolk of hyper-immunized hens and represent a relatively inexpensive source of antibodies. Specific IgY can be produced by immunizing chickens with the target antigen and then purifying from the egg yolk. Chicken IgY has been widely explored as a clinical anti-infective material for prophylaxis, preventive medicine, and therapy of infectious diseases. Administered non-systemically, IgY antibodies are safe and effective drugs. Moreover, passive immunization with avian antibodies could become an effective alternative therapy, as these can be obtained relatively simply, cost-efficiently, and produced on a large scale. Here, we highlight the potential use of polyclonal avian IgY antibodies as an oral prophylactic treatment for respiratory viral diseases, such as COVID-19, for which no vaccine is yet available.

Effect of antibiotic to induce Clostridioides difficile-susceptibility and infectious strain in a mouse model of Clostridioides difficile infection and recurrence

The anaerobic bacterium Clostridioides difficile is the leading cause of antibiotic-associated diarrhea that can culminate in life-threating colitis. During the C. difficile infection (CDI), C. difficile produces toxins that generate the clinical symptoms of the disease, and produce spores, which persist in the host during antibiotic treatment and can cause recurrent CDI (R-CDI). In this work, we aimed to compare three antibiotic regimens in the susceptibility of mice to CDI and R-CDI (i.e., antibiotic cocktail followed by clindamycin, 5 days of cefoperazone and 10 days of cefoperazone) with three different C. difficile isolates (i.e., strains 630; R20291, and VPI 10463). We observed that the severity of the clinical symptoms of CDI and R-CDI was dependent on the antibiotic treatment used to induce C. difficile-susceptibility, and that the three strains generated a different onset to diarrhea and weight loss in mice that were administrated with the same antibiotic treatment and which differed in comparison to the effect previously reported by other research groups. Our results suggest that, in our experimental conditions, in those animals treated with antibiotic cocktail followed by clindamycin, infection with strain R20291 had the highest diarrhea manifestation in comparison to strains 630 and VPI 10463. In animals treated with cefoperazone for 5 days, infection with strains R20291 or 630 had the highest diarrhea manifestation in comparison to VPI 10463, while in animals treated with cefoperazone for 10 days, infection with strain R20291 or VPI 10463, but not 630, had the highest diarrhea manifestation.

Early career interview: Marjorie Pizarro-Guajardo, Universidad Andrés Bello

Marjorie Pizarro-Guajardo is a postdoctoral fellow at the Universidad Andrés Bello (Santiago, Chile), where she studies Clostridium difficile spores. She won the 2019 Future Science Future Star Award. Here she tells us about her career to date, and how she felt winning the award.

Anti-PcrV IgY antibodies protect against Pseudomonas aeruginosa infection in both acute pneumonia and burn wound models

Pseudomonas aeruginosa is a common nosocomial pathogen in burn patients, and rapidly acquires antibiotic resistance; thus, developing an effective therapeutic approach is the most promising strategy for combating infection. Type III secretion system (T3SS) translocates bacterial toxins into the cytosol of the targeted eukaryotic cells, which plays important roles in the virulence of P. aeruginosa infections in both acute pneumonia and burn wound models. The PcrV protein, a T3SS translocating protein, is required for T3SS function and is a well-validated target in animal models of immunoprophylactic strategies targeting P. aeruginosa. In the present study, we evaluated the protective efficacy of chicken egg yolk antibodies (IgY) raised against recombinant PcrV (r-PcrV) in both acute pneumonia and burn wound models. R-PcrV protein was generated by expressing the pcrV gene (cloned in pET-28a vector) in E. coli BL-21. Anti-PcrV IgY was obtained by immunization of hen. Anti-PcrV IgY induced greater protection in P. aeruginosamurine acute pneumonia and burn wound models than control IgY (C-IgY) and PBS groups. Anti-PcrV IgY improved opsonophagocytic killing and inhibition of bacterial invasion of host cells. Taken together, our data provide evidence that anti-PcrV IgY can be a promising therapeutic candidate for combating P. aeruginosa infections.

Egg yolk antibodies (IgY) and their applications in human and veterinary health: A review

Egg yolk constitutes a relevant alternative source of antibodies. It presents some advantages over mammalian serum immunoglobulins regarding productivity, animal welfare and specificity. The main immunoglobulin present in avian blood (IgY) is transmitted to their offspring and accumulates in egg yolks, which enables the non-invasive harvesting of high amounts of antibodies. Moreover, due to structural differences and phylogenetic distance, IgY is more suitable for diagnostic purposes than mammalian antibodies, since it does not react with certain components of the human immune system and displays greater avidity for mammalian conserved proteins. IgY has been extensively used in health researches, as both therapeutic and diagnostic tool. This article aims to review its applications in both human and veterinary health.

Phagolysosomal activity of macrophages in Nile tilapia (Oreochromis niloticus) infected in vitro by Aeromonas hydrophila: Infection and immunotherapy

The biochemical mechanisms involved in phagocytosis and the intracellular survival of Aeromonas hydrophila (Ah) in host macrophages (MΦs) are complex processes that affect infection success or failure. Thus, in the present study, we described the in vitro infection of Nile tilapia MΦs by a homologous bacterium and tested the effects of anti-A. hydrophila immunoglobulin Y (IgY) on the phagolysosomal activity and intracellular survival of the pathogen. The anti-Ah IgY modulated lysosomal acid phosphatase (LAP) activity as well as the production of reactive oxygen intermediates (ROIs) and nitric oxide (NO), thereby potentiating phagocytosis and the elimination of Ah. Thus, we assume that the specific IgY had a beneficial effect on infection control and postulated the use of the Nile tilapia MΦs as an important in vitro experimental model for the functional and therapeutic study of Ah infection.

Risks Related to High-Dosage Recombinant Antimicrobial Peptide Microcin J25 in Mice Model: Intestinal Microbiota, Intestinal Barrier Function, and Immune Regulation

Antimicrobial peptide (AMP) can be a promising alternative in various domains. However, further risk information is required. In this study, mice were orally administrated different dosages of recombinant AMP microcin J25 (4.55, 9.1, and 18.2 mg/kg; MccJ25) for 1 week, and the toxicity risk impacts were examined. We evidenced that middle-dosage administration mice had a lower inflammation, better body weight, and ameliorated mucosal morphology, accompanied by reduced intestinal permeability and tighter intestinal barrier. Fecal microbiota composition analysis in middle- or low-dosage mice revealed the Bifidobacterium count was increased and the coliform bacteria count was decreased, and increased in short-chain fatty acid levels. Unexpectedly, there was a risk that high-dosage mice increased intestinal permeability and imbalance of intestinal bacteria. Taken together, these data indicated a safe threshold for usage of MccJ25 in clinical practice. Such studies can effectively enhance the safety of various aspects such as food preservative and drug.

Indomethacin increases severity of Clostridium difficile infection in mouse model

AIM

To evaluate the effect on the nonsteroidal anti-inflammatory drug indomethacin on Clostridium difficile infection (CDI) severity.

MATERIALS & METHODS

Indomethacin was administered in two different mouse models of antibiotic-associated CDI in two different facilities, using a low and high dose of indomethacin.

RESULTS

Indomethacin administration caused weight loss, increased the signs of severe infection and worsened histopathological damage, leading to 100% mortality during CDI. Indomethacin-treated, antibiotic-exposed mice infected with C. difficile had enhanced intestinal inflammation with increased expression of KC, IL-1β and IL-22 compared with infected mice unexposed to indomethacin.

CONCLUSION

These results demonstrate a negative impact of nonsteroidal anti-inflammatory drugs on antibiotic-associated CDI in mice and suggest that targeting the synthesis or signaling of prostaglandins might be an approach to ameliorating the severity of CDI.

Application of Antibody-Mediated Therapy for Treatment and Prevention of Clostridium difficile Infection

Clostridium difficile causes antibiotic- and healthcare-associated diarrhea, which is characterized by a high mortality rate (5–15%) and high recurrence rate of 20% or more. Therapeutic alternatives to antibiotics are urgently needed to improve the overall cure rate. Among these, therapeutic antibodies have shown promising results in clinical studies. Herein, the authors review current monoclonal and polyclonal anti- C. difficile antibodies that have entered the clinical development stage, either for systemic administration or by the oral route. The antibodies can be applied as monotherapy or in combination with standard-of-care to treat an infection with C. difficile or to protect from a recurrence. Bezlotoxumab is the first antibody for secondary prevention of recurrence of C. difficile infection approved by the regulatory agencies in US and Europe. The human monoclonal antibody is administered systemically to patients receiving oral standard-of–care antibiotics. Other antibodies are currently in the clinical pipeline, and some are intended for oral use. They show a good safety profile, high efficacy and low production costs, and can be considered promising therapies of the future. The most promising orally administered drug candidate is a bovine antibody from hyperimmune colostral milk, which is in an advanced clinical development stage. Which antibody will enter the market is dependent on its bioavailability at the site of infection as well as its activity against C. difficile toxins, protection against colonization and possible action on spore formation. The antibody must demonstrate a clear benefit in comparison with other available treatment options to be considered for use by clinicians.

Anti-lipopolysaccharide egg yolk antibodies enhance the phagocytosis of mammalian phagocytes

Macrophages play crucial roles in combatting infectious diseases by promoting inflammation and phagocytosis. The decline of macrophage phagocytic function will bring many serious consequences, including weakened pathogen clearance. As an avian antibody, immunoglobulin Y (IgY) has been widely used in preventing and treating infectious diseases, but whether it can enhance the phagocytic ability of mammalian macrophages in order to clear pathogens is still unknown. In this study, mouse peritoneal macrophages and THP-1 cells were cultured with anti-lipopolysaccharide (LPS) IgY in vivo or in vitro, respectively. Morphological observation, ELISA, fluorescence immunoassays and flow cytometry were used to study whether IgY could enhance phagocytosis of mammalian macrophages. It was found that without anti-LPS IgY, mouse peritoneal macrophages showed adherent growth with no differentiation and little pseudopod extension; but with anti-LPS IgY, peritoneal macrophages presented more significant characteristics in adherent growth, extension deformation and protruding pseudopods. With flow cytometry, the macrophages from mice injected with anti-LPS IgY exhibited a significantly higher percentage of phagocytosis and index (90.83±2.59% and 4.45±0.13 respectively) compared with phosphate buffered saline (PBS) groups (64.32±1.5%, and 2.36±0.11) and non-immunized groups (65.94%±1.4%, and 2.4±0.15). With phorbol-12-myristate-13-acetate (PMA)-induced THP-1 cells, similar results were found; the percentage and index were significantly higher, with larger body and more pseudopods, for THP-1 cells that were co-incubated with anti-LPS IgY (79.83±0.38% and 2.64±0.03), compared with cells that were co-incubated with PBS (68.07±0.52%, and 1.88±0.03) or non-immunized IgY (74.89±1.14% and 2.30±0.02). The results showed that anti-LPS IgY was effective in promoting the growth of macrophages, pseudopod extension and stronger phagocytic capacity. Our study indicated that anti-LPS IgY could enhance the phagocytic capacity of mammalian macrophages to internalize pathogens more effectively with larger body and more pseudopods. This may be important to encourage IgY to be used to prevent and treat infectious diseases.

Lauric Acid Is an Inhibitor of Clostridium difficile Growth in Vitro and Reduces Inflammation in a Mouse Infection Model

Clostridium difficile is a Gram-positive, spore-forming anaerobic human gastrointestinal pathogen. C. difficile infection (CDI) is a major health concern worldwide, with symptoms ranging from diarrhea to pseudomembranous colitis, toxic megacolon, sepsis, and death. CDI onset and progression are mostly caused by intestinal dysbiosis and exposure to C. difficile spores. Current treatment strategies include antibiotics; however, antibiotic use is often associated with high recurrence rates and an increased risk of antibiotic resistance. Medium-chain fatty acids (MCFAs) have been revealed to inhibit the growth of multiple human bacterial pathogens. Components of coconut oil, which include lauric acid, have been revealed to inhibit C. difficile growth in vitro. In this study, we demonstrated that lauric acid exhibits potent antimicrobial activities against multiple toxigenic C. difficile isolates in vitro. The inhibitory effect of lauric acid is partly due to reactive oxygen species (ROS) generation and cell membrane damage. The administration of lauric acid considerably reduced biofilm formation and preformed biofilms in a dose-dependent manner. Importantly, in a mouse infection model, lauric acid pretreatment reduced CDI symptoms and proinflammatory cytokine production. Our combined results suggest that the naturally occurring MCFA lauric acid is a novel C. difficile inhibitor and is useful in the development of an alternative or adjunctive treatment for CDI.