Induction of the mitochondrial pathway of apoptosis by enrofloxacin in the context of the safety issue of its use in poultry.

The overuse of antibiotics in both humans and livestock has led to the antibiotic resistance phenomenon which is now considered one of the biggest problems in the modern world. Some antibiotics used to control or prevent infections in livestock poultry were registered a long time ago, and as a result, data on the possible side effects of their use, both for birds and humans, are incomplete and should be updated. An example of such an antibiotic is enrofloxacin which has been widely used in poultry since 1989. Data in recent years have begun to indicate that this antibiotic induces the process of apoptosis in diverse types of eukaryotic cells. Unfortunately, such studies have never been conducted on chicken models even though it is in poultry that this antibiotic is most commonly used. Therefore, the purpose of this work was to investigate whether enrofloxacin induces apoptosis in chicken cells of the UMNSAH/DF-1 line and to study the molecular mechanism of its action. The results of these experiments indicated that enrofloxacin induces apoptosis in chicken cells but not in human HEK-293 and PC3 cells. This induction was accompanied by changes in the morphology and size of mitochondria, the process of apoptosome formation and activation of executive caspases, which clearly indicates the role of the mitochondrial pathway in the induction of apoptosis by enrofloxacin. This study is the first to show the toxicity of enrofloxacin against chicken cells and to demonstrate the exact mechanism of its action. The results presented in this work show the need to monitor the concentration of antibiotic residues in poultry foods as well as to study their impact on public health to guarantee consumer safety and prevent the phenomenon of antibiotic resistance in bacteria.

Bacteriophages-Dangerous Viruses Acting Incognito or Underestimated Saviors in the Fight against Bacteria?

The steadily increasing number of drug-resistant bacterial species has prompted the search for alternative treatments, resulting in a growing interest in bacteriophages. Although they are viruses infecting bacterial cells, bacteriophages are an extremely important part of the human microbiota. By interacting with eukaryotic cells, they are able to modulate the functioning of many systems, including the immune and nervous systems, affecting not only the homeostasis of the organism, but potentially also the regulation of pathological processes. Therefore, the aim of this review is to answer the questions of (i) how animal/human immune systems respond to bacteriophages under physiological conditions and under conditions of reduced immunity, especially during bacterial infection; (ii) whether bacteriophages can induce negative changes in brain functioning after crossing the blood-brain barrier, which could result in various disorders or in an increase in the risk of neurodegenerative diseases; and (iii) how bacteriophages can modify gut microbiota. The crucial dilemma is whether administration of bacteriophages is always beneficial or rather if it may involve any risks.

The NMR structure of the Orf63 lytic developmental protein from lambda bacteriophage.

The orf63 gene resides in a region of the lambda bacteriophage genome between the exo and xis genes and is among the earliest genes transcribed during infection. In lambda phage and Shiga toxin (Stx) producing phages found in enterohemorrhagic Escherichia coli (EHEC) associated with food poisoning, Orf63 expression reduces the host survival and hastens the period between infection and lysis thereby giving it pro-lytic qualities. The NMR structure of dimeric Orf63 reveals a fold consisting of two helices and one strand that all make extensive intermolecular contacts. Structure-based data mining failed to identify any Orf63 homolog beyond the family of temperate bacteriophages. A machine learning approach was used to design an amphipathic helical ligand that bound a hydrophobic cleft on Orf63 with micromolar affinity. This approach may open a new path towards designing therapeutics that antagonize the contributions of Stx phages in EHEC outbreaks.

Bacteriophage DNA induces an interrupted immune response during phage therapy in a chicken model.

One of the hopes for overcoming the antibiotic resistance crisis is the use of bacteriophages to combat bacterial infections, the so-called phage therapy. This therapeutic approach is generally believed to be safe for humans and animals as phages should infect only prokaryotic cells. Nevertheless, recent studies suggested that bacteriophages might be recognized by eukaryotic cells, inducing specific cellular responses. Here we show that in chickens infected with Salmonella enterica and treated with a phage cocktail, bacteriophages are initially recognized by animal cells as viruses, however, the cGAS-STING pathway (one of two major pathways of the innate antiviral response) is blocked at the stage of the IRF3 transcription factor phosphorylation. This inhibition is due to the inability of RNA polymerase III to recognize phage DNA and to produce dsRNA molecules which are necessary to stimulate a large protein complex indispensable for IRF3 phosphorylation, indicating the mechanism of the antiviral response impairment.