The contribution of phage therapy to medical knowledge

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.

Phage Therapy vs. the Use of Antibiotics in the Treatment of Salmonella-Infected Chickens: Comparison of Effects on Hematological Parameters and Selected Biochemical Markers

Previous studies indicated that the use of a phage cocktail, composed of bacteriophages vB_SenM-2 and vB_Sen-TO17, is effective in killing cells of Salmonella enterica serovars Typhimurium and Enteritidis in vitro and in the Galleria mellonella animal model as efficiently as antibiotics (enrofloxacin or colistin) and induced fewer deleterious changes in immune responses. Here, we investigated the effects of this phage cocktail on the hematological parameters and selected biochemical markers in chickens infected with S. enterica serovar Typhimurium, in comparison to those caused by enrofloxacin or colistin. We found that treatment with antibiotics (especially with enrofloxacin) caused nonbeneficial effects on red blood cell parameters, including hematocrit, MCV, MCH, and MCHC. However, Salmonella-induced changes in the aforementioned parameters were normalized by the use of the phage cocktail. Importantly, hepatotoxicity was suggested to be induced by both antibiotics on the basis of increased alanine transaminase (ALT) and aspartate aminotransferase (AST) activities, in contrast to the phage cocktail, which did not influence these enzymes. We conclude that phage therapy with the cocktail of vB_SenM-2 and vB_Sen-TO17 in Salmonella-infected chickens is not only as effective as antibiotics but also significantly safer for the birds than enrofloxacin and colistin.

How Interest in Phages Has Bloomed into a Leading Medical Research Activity in Poland

Poland has a leading position in phage therapy, as reflected by the number of patients treated and relevant publications in quality journals. The Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences was established by Ludwik Hirszfeld, a prominent microbiologist and serologist who also initiated studies on phages and pioneered the activities that set into motion phage therapy at the Institute. To achieve this goal, Hirszfeld had to overcome many difficulties in a post-war Poland. He died a month before the official start of the Institute's activity and was not able to witness the advancement of the Institute bearing his name. However, his hard work and dedication have been recently rewarded. In a recent evaluation of scientific performance, the Institute received the highest ranking in medical sciences among all universities and research institutions in Poland. One could consider it a posthumous tribute to the memory of L. Hirszfeld, being well-deserved on the grounds of the Institute's achievements (especially in the field of phage therapy) as well as his life and work.

Modification of the immune response by bacteriophages alters methicillin-resistant Staphylococcus aureus infection

There is an urgent need to develop phage therapies for multidrug-resistant bacterial infections. However, although bacteria have been shown to be susceptible to phage therapy, phage therapy is not sufficient in some cases. PhiMR003 is a methicillin-resistant Staphylococcus aureus phage previously isolated from sewage influent, and it has demonstrated high lytic activity and a broad host range to MRSA clinical isolates in vitro. To investigate the potential of phiMR003 for the treatment of MRSA infection, the effects of phiMR003 on immune responses in vivo were analysed using phiMR003-susceptible MRSA strains in a mouse wound infection model. Additionally, we assessed whether phiMR003 could affect the immune response to infection with a nonsusceptible MRSA strain. Interestingly, wounds infected with both susceptible and nonsusceptible MRSA strains treated with phiMR003 demonstrated decreased bacterial load, reduced inflammation and accelerated wound closure. Moreover, the infiltration of inflammatory cells in infected tissue was altered by phiMR003. While the effects of phiMR003 on inflammation and bacterial load disappeared with heat inactivation of phiMR003. Transcripts of proinflammatory cytokines induced by lipopolysaccharide were reduced in mouse peritoneal macrophages. These results show that the immune modulation occurring as a response to the phage itself improves the clinical outcomes of phage therapy.

A Thorough Synthesis of Phage Therapy Unit Activity in Poland-Its History, Milestones and International Recognition

The year 2020 marked 15 years of the Phage Therapy Unit in Poland, the inception of which took place just one year after Poland's accession to the European Union (2004). At first sight, it is hard to find any connection between these two events, but in fact joining the European Union entailed the need to adapt the regulatory provisions concerning experimental treatment in humans to those that were in force in the European Union. These changes were a solid foundation for the first phage therapy center in the European Union to start its activity. As the number of centers conducting phage therapy in Europe and in the world constantly and rapidly grows, we want to grasp the opportunity to take a closer look at the over 15-year operation of our site by analyzing its origins, legal aspects at the local and international levels and the impressive number and diversity of cases that have been investigated and treated during this time. This article is a continuation of our work published in 2020 summarizing a 100-year history of the development of phage research in Poland.