Ciprofloxacin Affects Host Cells by Suppressing Expression of the Endogenous Antimicrobial Peptides Cathelicidins and Beta-Defensin-3 in Colon Epithelia

Exploring the Localization of Siderophore-Mediated Cargo Delivery in Gram-Negative Bacteria Using 3-Hydroxypyridin-4(1H)-one-Fluorescein Probes

The design of siderophore-antibiotic conjugates is a promising strategy to overcome drug resistance in negative bacteria. However, accumulating studies have shown that only those antibiotics acting on the cell wall or cell membrane multiply their antibacterial effects when coupled with siderophores, while antibiotics acting on targets in the cytoplasm of bacteria do not show an obvious enhancement of their antibacterial effects when coupled with siderophores. To explore the causes of this phenomenon, we synthesized several conjugate probes using 3-hydroxypyridin-4(1H)-ones as siderophores and replacing the antibiotic cargo with 5-carboxyfluorescein (5-FAM) or malachite green (MG) cargo. By monitoring changes in the fluorescence intensity of FAM conjugate 20 in bacteria, the translocation of the conjugate across the outer membranes of Gram-negative pathogens was confirmed. Further, the use of the fluorogen activating protein(FAP)/MG system revealed that 3-hydroxypyridin-4(1H)-one-MG conjugate 26 was ultimately distributed mainly in the periplasm rather than being translocated into the cytosol of Escherichia coli and Pseudomonas aeruginosa PAO1. Additional mechanistic studies suggested that the uptake of the conjugate involved the siderophore-dependent iron transport pathway and the 3-hydroxypyridin-4(1H)-ones siderophore receptor-dependent mechanism. Meanwhile, we demonstrated that the conjugation of 3-hydroxypyridin-4(1H)-ones to the fluorescein 5-FAM can reduce the possibility of the conjugates crossing the membrane layers of mammalian Vero cells by passive diffusion, and the advantages of the mono-3-hydroxypyridin-4(1H)-ones as a delivery vehicle in the design of conjugates compared to the tri-3-hydroxypyridin-4(1H)-ones. Overall, this work reveals the localization rules of 3-hydroxypyridin-4(1H)-ones as siderophores to deliver the cargo into Gram-negative bacteria. It provides a theoretical basis for the subsequent design of siderophore-antibiotic conjugates, especially based on 3-hydroxypyridin-4(1H)-ones as siderophores.

Antibiotics, Sedatives, and Catecholamines Further Compromise Sepsis-Induced Immune Suppression in Peripheral Blood Mononuclear Cells

OBJECTIVES

We hypothesized that the immunosuppressive effects associated with antibiotics, sedatives, and catecholamines amplify sepsis-associated immune suppression through mitochondrial dysfunction, and there is a cumulative effect when used in combination. We thus sought to determine the impact of the exemplar drugs ciprofloxacin, propofol, and norepinephrine, used alone and in combination, at clinically relevant concentrations, on the ex vivo functionality of peripheral blood mononuclear cells (PBMCs) drawn from healthy, infected, and septic individuals.

DESIGN

In vitro/ex vivo investigation.

SETTING

University laboratory.

SUBJECTS

Healthy volunteers, infected (nonseptic) patients in the emergency department, and septic ICU patients.

INTERVENTIONS

PBMCs were isolated from these subjects and treated with ciprofloxacin (100 µg/mL), propofol (50 µg/mL), norepinephrine (10 µg/mL), or all three drugs combined, with and without lipopolysaccharide (100 ng/mL) for 6 or 24 hours. Comparison was made between study groups and against untreated cells. Measurements were made of cell viability, cytokine production, phagocytosis, human leukocyte antigen-DR (HLA-DR) status, mitochondrial membrane potential, mitochondrial reactive oxygen species production, and oxygen consumption. Gene expression in immune and metabolic pathways was investigated in PBMCs sampled from healthy volunteers coincubated with septic serum.

MEASUREMENTS AND RESULTS

Coincubation with each of the drugs reduced cytokine production and phagocytosis in PBMCs isolated from septic patients, and healthy volunteers coincubated with septic serum. No effect was seen on HLA-DR surface expression. No cumulative effects were seen with the drug combination. Sepsis-induced changes in gene expression and mitochondrial functionality were not further affected by addition of any of the drugs.

CONCLUSION

Drugs commonly used in critical care lead to significant immune dysfunction ex vivo and enhance sepsis-associated immunosuppression. Further studies are required to identify underlying mechanisms and potential impact on patient outcomes.

New treatment approaches for Clostridioides difficile infections: alternatives to antibiotics and fecal microbiota transplantation

Clostridioides difficile causes a range of debilitating intestinal symptoms that may be fatal. It is particularly problematic as a hospital-acquired infection, causing significant costs to the health care system. Antibiotics, such as vancomycin and fidaxomicin, are still the drugs of choice for C. difficile infections, but their effectiveness is limited, and microbial interventions are emerging as a new treatment option. This paper focuses on alternative treatment approaches, which are currently in various stages of development and can be divided into four therapeutic strategies. Direct killing of C. difficile (i) includes beside established antibiotics, less studied bacteriophages, and their derivatives, such as endolysins and tailocins. Restoration of microbiota composition and function (ii) is achieved with fecal microbiota transplantation, which has recently been approved, with standardized defined microbial mixtures, and with probiotics, which have been administered with moderate success. Prevention of deleterious effects of antibiotics on microbiota is achieved with agents for the neutralization of antibiotics that act in the gut and are nearing regulatory approval. Neutralization of C. difficile toxins (iii) which are crucial virulence factors is achieved with antibodies/antibody fragments or alternative binding proteins. Of these, the monoclonal antibody bezlotoxumab is already in clinical use. Immunomodulation (iv) can help eliminate or prevent C. difficile infection by interfering with cytokine signaling. Small-molecule agents without bacteriolytic activity are usually selected by drug repurposing and can act via a variety of mechanisms. The multiple treatment options described in this article provide optimism for the future treatment of C. difficile infection.

Antibiotic associated diarrhea in outpatient pediatric antibiotic therapy

BACKGROUND

Antibiotic-associated diarrhea is one of the most frequent side effects of antimicrobial therapy. We assessed the epidemiological data of antibiotic-associated diarrhea in pediatric patients in our region.

METHODS

The prospective multi-center study included pediatric patients who were initiated an oral antibiotic course in outpatient clinics and followed in a well-established surveillance system. This follow-up system constituded inclusion of patient by the primary physician, supply of family follow-up charts to the family, passing the demographics and clinical information of patient to the Primary Investigator Centre, and a close telephone follow-up of patients for a period of eight weeks by the Primary Investigator Centre.

RESULTS

A result of 758 cases were recruited in the analysis which had a frequency of 10.4% antibiotic-associated diarrhea. Among the cases treated with amoxicillin-clavulanate 10.4%, and cephalosporins 14.4% presented with antibiotic-associated diarrhea. In the analysis of antibiotic-associated diarrhea occurrence according to different geographical regions of Turkey, antibiotic-associated diarrhea episodes differed significantly (p = 0.014), particularly higher in The Eastern Anatolia and Southeastern Anatolia. Though most commonly encountered with cephalosporin use, antibiotic-associated diarrhea is not a frequent side effect.

CONCLUSION

This study on pediatric antibiotic-associated diarrhea displayed epidemiological data and the differences geographically in our region.

Identifying hub genes of calcific aortic valve disease and revealing the immune infiltration landscape based on multiple WGCNA and single-cell sequence analysis

BACKGROUND

Calcific aortic valve disease (CAVD) is a progressive fibrocalcific disease that can be treated only through valve replacement. This study aimed to determine the role of hub genes and immune cell infiltration in CAVD progression.

METHODS

In this study, bioinformatics analysis was used to identify hub genes involved in CAVD. The datasets were downloaded from the Gene Expression Omnibus (GEO) database. Gene expression differences were evaluated via pathway and Gene Ontology analyses. Weighted gene co-expression network analysis (WGCNA) and differentially expressed genes were used to screen hub genes. The CIBERSORT algorithm was used to compare immune infiltration into the calcified aortic valve based on the hub genes between high- and low-expression groups. We also performed single-cell RNA sequencing based on six different human aortic valve leaflets. The expression of hub genes was identified in human and mouse samples through quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry, immunofluorescence, and ELISA, and clinical features of the patients were investigated.

RESULTS

In total, 454 differentially expressed genes were obtained from the GEO database. WGCNA was used to find 12 co-expression modules in the Array Express database, of which one hub module (brown module) was most correlated with CAVD. Two hub genes were identified after combining the differentially expressed genes S100A8 and S100A9. Regarding these genes, the immune infiltration profiles varied between high- and low-expression groups. Compared with that in the low hub gene expression group, the high hub gene expression group had a higher proportion of activated NK cells (p < 0.01) and M1 macrophages (p < 0.05). The expression of S100A8 and S100A9 was consistent with single-gene RNA sequencing results, confirming that the expression levels of these two hub genes are significantly upregulated in patients with CAVD (p < 0.01). Furthermore, these results were verified using mouse and human samples by performing immunofluorescence, immunohistochemistry, qPCR, and ELISA analyses. Finally, the localization of S100A8 and S100A9 in monocytes and macrophages was confirmed via immunofluorescence using human aortic valves.

CONCLUSION

These results demonstrate that S100A8 and S100A9 are two hub genes involved in CAVD, which might play an important role in its development through immune-related signaling pathways.

Toxicity induced by ciprofloxacin and enrofloxacin: oxidative stress and metabolism

Ciprofloxacin (CIP) (human use) and enrofloxacin (ENR) (veterinary use) are synthetic anti-infectious medications that belong to the second generation of fluoroquinolones. They have a wide antimicrobial spectrum and strong bactericidal effects at very low concentrations via enzymatic inhibition of DNA gyrase and topoisomerase IV, which are required for DNA replication. They also have high bioavailability, rapid absorption with favorable pharmacokinetics and excellent tissue penetration, including cerebral spinal fluid. These features have made them the most applied antibiotics in both human and veterinary medicine. ENR is marketed exclusively for animal medicine and has been widely used as a therapeutic veterinary antibiotic, resulting in its residue in edible tissues and aquatic environments, as well as the development of resistance and toxicity. Estimation of the risks to humans due to antimicrobial resistance produced by CIP and ENR is important and of great interest. Moreover, in rare cases due to their overdose and/or prolonged administration, the development of CIP and ENR toxicity may occur. The toxicity of these fluoroquinolones antimicrobials is mainly related to reactive oxygen species (ROS) and oxidative stress (OS) generation, besides metabolism-related toxicity. Therefore, CIP is restricted in pregnant and lactating women, pediatrics and elderly similarly ENR do in the veterinary field. This review manuscript aims to identify the toxicity induced by ROS and OS as a common sequel of CIP and ENR. Furthermore, their metabolism and the role of metabolizing enzymes were reported.

IL-27 induces LL-37/CRAMP expression from intestinal epithelial cells: implications for immunotherapy of Clostridioides difficile infection

Clostridioides difficile infection is currently the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. Cathelicidins, a major group of natural antimicrobial peptides, have antimicrobial and immunomodulatory activities in Clostridioides difficile infection. Here, we have shown that cytokine IL-27 induced human cathelicidin antimicrobial peptide (LL-37) expression in primary human colonic epithelial cells. IL-27 receptor-deficient mice had impaired expression of cathelicidin-related antimicrobial peptide (CRAMP, mouse homolog for human LL-37) after Clostridioides difficile infection, and restoration of CRAMP improved Clostridium difficile clearance and reduced mortality in IL-27 receptor-deficient mice after Clostridioides difficile challenge. In clinical samples from 119 patients with Clostridioides difficile infection, elevated levels of IL-27 were positively correlated with LL-37 in the sera and stools. These findings suggest that IL-27 may be involved in host immunity against Clostridioides difficile infection via induction of LL-37/CRAMP. Therefore, IL-27-LL-37 axis may be a valuable pathway in the development of immune-based therapy.

Host Directed Therapy Against Infection by Boosting Innate Immunity

The innate immune system constitutes the first line of defense against invading pathogens, regulating the normal microbiota and contributes to homeostasis. Today we have obtained detailed knowledge on receptors, signaling pathways, and effector molecules of innate immunity. Our research constellation has focused on ways to induce the expression of antimicrobial peptides (AMPs), the production of oxygen species (ROS and NO), and to activate autophagy, during the last two decades. These innate effectors, with different mechanisms of action, constitute a powerful defense armament in phagocytes and in epithelial cells. Innate immunity does not only protect the host from invading pathogens, but also regulates the composition of the microbiota, which is an area of intense research. Notably, some virulent bacteria have the capacity to downregulate innate defenses and can thereby cause invasive disease. Understanding the detailed mechanisms behind pathogen-mediated suppression of innate effectors are currently in progress. This information can be of importance for the development of novel treatments based on counteraction of the downregulation; we have designated this type of treatment as host directed therapy (HDT). The concept to boost innate immunity may be particularly relevant as many pathogens are developing resistance against classical antibiotics. Many pathogens that are resistant to antibiotics are sensitive to the endogenous effectors included in early host defenses, which contain multiple effectors working in cooperation to control infections. Here, we review recent data related to downregulation of AMPs by pathogenic bacteria, induction of innate effector mechanisms, including cytokine-mediated effects, repurposed drugs and the role of antibiotics as direct modulators of host responses. These findings can form a platform for the development of novel treatment strategies against infection and/or inflammation.

A practical guide for probiotics applied to the case of antibiotic-associated diarrhea in The Netherlands

BACKGROUND

Antibiotic-associated diarrhea (AAD) is a side-effect frequently associated with the use of broad spectrum antibiotics. Although a number of clinical studies show that co-administration of specific probiotics reduces the risk for AAD, there is still unclarity among healthcare professionals on the recommendation of probiotic products. This paper aims at a practical guide to inform healthcare professionals, patients and consumers about the exact product characteristics of available probiotics with a proven efficacy to prevent AAD.

METHODS

The workflow in this paper includes three consecutive steps: 1) systematic review of relevant clinical studies for effective probiotics by a meta-analysis, 2) compilation of a list of available probiotic products, and 3) recommendation of probiotic products that match effective formulations. Our systematic review on the efficacy of probiotics for the prevention of AAD included only studies with randomized, double blind placebo-controlled trials, a clear definition of antibiotic associated diarrhea, and a probiotic administration regime for at least the duration of the antibiotic therapy.

RESULTS

Using our inclusion criteria, we selected 32 out of 128 identified trials and pooled the results of these studies for each specific dairy product and food supplement. The results indicate a total of seven single or multiple-strain formulations favoring the probiotic treatment group, with the strain Lactobacillus rhamnosus GG being the most effective [relative risk ratio of probiotic versus placebo 0.30 (95% CI 0.16-0.5)]. We selected products for recommendation from a compiled list of all probiotic dairy products and food supplements available in The Netherlands and categorized them into groups of products showing effects against the incidence of AAD in at least one, two or three independent clinical studies. We excluded all products which did not unambiguously declare on the label the specific probiotic strain(s) and the number of colony forming units.

CONCLUSION

Here we present a practical guide that informs healthcare professionals and patients on the availability of probiotic products with a proven efficacy for the prevention of AAD.

Alternatives to antibiotics-a pipeline portfolio review

Antibiotics have saved countless lives and enabled the development of modern medicine over the past 70 years. However, it is clear that the success of antibiotics might only have been temporary and we now expect a long-term and perhaps never-ending challenge to find new therapies to combat antibiotic-resistant bacteria. A broader approach to address bacterial infection is needed. In this Review, we discuss alternatives to antibiotics, which we defined as non-compound approaches (products other than classic antibacterial agents) that target bacteria or any approaches that target the host. The most advanced approaches are antibodies, probiotics, and vaccines in phase 2 and phase 3 trials. This first wave of alternatives to antibiotics will probably best serve as adjunctive or preventive therapies, which suggests that conventional antibiotics are still needed. Funding of more than £1·5 billion is needed over 10 years to test and develop these alternatives to antibiotics. Investment needs to be partnered with translational expertise and targeted to support the validation of these approaches in phase 2 trials, which would be a catalyst for active engagement and investment by the pharmaceutical and biotechnology industry. Only a sustained, concerted, and coordinated international effort will provide the solutions needed for the future.