Salmonella typhimurium may support cancer treatment: a review

Salmonella-based therapeutic strategies: improving tumor microenvironment and bringing new hope for cancer immunotherapy

Immunotherapy has revolutionized cancer treatment, yet its effectiveness is limited by immunosuppressive tumor microenvironment (TME). To overcome this challenge, innovative strategies to effectively modulate the TME are urgently needed. Over the past decades, bacteria-mediated cancer immunotherapy has recaptured increasing attention, driven by advances in synthetic biology, genetic engineering and our knowledge of host-pathogen interactions. Among various bacterial species, Salmonella has emerged as a leading candidate with significant therapeutic potential due to its broad-spectrum anti-tumor activity, tumor-targeting ability, immunomodulatory effects, oncolytic properties, genetic programmability, and engineering flexibility. These characteristics enable Salmonella to reshape the immunosuppressive TME, thereby enhancing anti-tumor efficacy. This review elaborates the regulatory effects of Salmonella on key components of the TME, the versatile engineering strategies for optimizing Salmonella's ability to modulate the TME, and recent advancements in combination cancer therapies. We also summarize current clinical applications and discuss challenges of developing safer and more effective Salmonella-based cancer immunotherapy.

Impact on Human Health of Salmonella spp. and Their Lipopolysaccharides: Possible Therapeutic Role and Asymptomatic Presence Consequences

Epidemiologically, one of the most important concerns associated with introducing Salmonella spp. into the environment and food chain is the presence of asymptomatic carriers. The oncogenic and oncolytic activity of Salmonella and their lipopolysaccharides (LPSs) is important and research on this topic is needed. Even a single asymptomatic dose of the S. Enteritidis LPS (a dose that has not caused any symptoms of illness) in in vivo studies induces the dysregulation of selected cells and bioactive substances of the nervous, immune, and endocrine systems. LPSs from different species, and even LPSs derived from different serotypes of one species, can define different biological activities. The activity of low doses of LPSs derived from three different Salmonella serotypes (S. Enteritidis, S. Typhimurium, and S. Minnesota) affects the neurochemistry of neurons differently in in vitro studies. Studies on lipopolysaccharides from different Salmonella serotypes do not consider the diversity of their activity. The presence of an LPS from S. Enteritidis in the body, even in amounts that do not induce any symptoms of illness, may lead to unknown long-term consequences associated with its action on the cells and biologically active substances of the human body. These conclusions should be important for both research strategies and the pharmaceutical industry &.

Advancements of engineered live oncolytic biotherapeutics (microbe/virus/cells): Preclinical research and clinical progress

The proven efficacy of immunotherapy in fighting tumors has been firmly established, heralding a new era in harnessing both the innate and adaptive immune systems for cancer treatment. Despite its promise, challenges such as inefficient delivery, insufficient tumor penetration, and considerable potential toxicity of immunomodulatory agents have impeded the advancement of immunotherapies. Recent endeavors in the realm of tumor prophylaxis and management have highlighted the use of living biological entities, including bacteria, oncolytic viruses, and immune cells, as a vanguard for an innovative class of live biotherapeutic products (LBPs). These LBPs are gaining recognition for their inherent ability to target tumors. However, these LBPs must contend with significant barriers, including robust immune clearance mechanisms, cytotoxicity and other in vivo adverse effects. Priority must be placed on enhancing their safety and therapeutic indices. This review consolidates the latest preclinical research and clinical progress pertaining to the exploitation of engineered biologics, spanning bacteria, oncolytic viruses, immune cells, and summarizes their integration with combination therapies aimed at circumventing current clinical impasses. Additionally, the prospective utilities and inherent challenges of the biotherapeutics are deliberated, with the objective of accelerating their clinical application in the foreseeable future.

Effects of intratumoral microbiota on tumorigenesis, anti-tumor immunity, and microbe-based cancer therapy

Intratumoral microbiota (IM) has emerged as a significant component of the previously thought sterile tumor microenvironment (TME), exerting diverse functions in tumorigenesis and immune modulation. This review outlines the historical background, classification, and diversity of IM, elucidating its pivotal roles in oncogenicity, cancer development, and progression, alongside its influence on anti-tumor immunity. The signaling pathways through which IM impacts tumorigenesis and immunity, including reactive oxygen species (ROS), β-catenin, stimulator of interferon genes (STING), and other pathways [NF-κB, Toll-like receptor (TLR), complement, RhoA/ROCK, PKR-like ER kinase (PERK)], are discussed comprehensively. Furthermore, we briefly introduce the clinical implications of IM, emphasizing its potential as a target for novel cancer therapies, diagnostic biomarkers, and prognostic indicators. Notably, microbe-based therapeutic strategies such as fecal microbiome transplantation (FMT), probiotics regulation, bacteriotherapy, bacteriophage therapy, and oncolytic virotherapy are highlighted. These strategies hold promise for enhancing the efficacy of current cancer treatments and warrant further exploration in clinical settings.

Attenuated Salmonella typhimurium L forms suppress tumor growth and promote apoptosis in murine ovarian tumors

To study the effects of attenuated Salmonella typhimurium L forms on the in vivo tumorigenicity and apoptosis of murine epithelial ovarian cancer cells, as well as the related mechanisms. Attenuated Salmonella typhimurium VNP20009 was induced into bacterial L forms by using antibiotic ceftriaxone. CCK-8 cell proliferation assay showed that attenuated S. typhimurium L forms can inhibit the proliferation of murine ovarian epithelial cancer ID8 cells. Attenuated ST L forms can induce apoptosis and inhibit invasion ability of epithelial ovarian cancer cells in vitro. TUNEL assay showed that attenuated ST L forms can induce apoptosis of ID8 cells in murine ovarian tumors. Meanwhile, attenuated ST L forms inhibit tumor growth in murine ovarian tumors. The tumorigenicity-related proteins of xenograft tumors detected by immunohistochemistry and fluorescence quantitative RT-PCR assays showed that attenuated ST L forms can reduce the expression of proteins that promote tumor growth and metastasis, such as Lgals9 and MMP9. This study confirmed that attenuated ST L forms can suppress tumor growth and promote apoptosis in murine ovarian tumors. Attenuated ST L forms may serve as a novel biological agent for bacterial-mediated tumor therapy in epithelial ovarian cancer.

Emerging therapeutic approaches for peritoneal metastases from gastrointestinal cancers

Peritoneal metastases from gastrointestinal malignancies present difficult management decisions, with options consisting primarily of systemic chemotherapy or major surgery with or without hyperthermic intraperitoneal chemotherapy. Current research is investigating expanding therapeutic modalities, and the aim of this review is to provide an overview of the existing and emerging therapies for the peritoneal metastases from gastrointestinal cancers, primarily through the recent literature (2015 and newer). These include the current data with systemic therapy and cytoreduction with hyperthermic intraperitoneal or pressurized intraperitoneal aerosol chemotherapy, as well as novel promising modalities under investigation, including dominating oncolytic viral therapy and adoptive cellular, biologic, and bacteria therapy, or nanotechnology. The novel diverse strategies, although preliminary and preclinical in murine models, individually and collectively contribute to the treatment of peritoneal metastases, offering hope for improved outcomes and quality of life. We foresee that these evolving treatment approaches will facilitate the transfer of knowledge and data among studies and advance discovery of new drugs and optimized treatments for patients with peritoneal metastases.

Salmonella enterica and outer membrane vesicles are current and future options for cancer treatment

Conventional cancer therapies have many limitations. In the last decade, it has been suggested that bacteria-mediated immunotherapy may circumvent the restrictions of traditional treatments. For example, Salmonella enterica is the most promising bacteria for treating cancer due to its intrinsic abilities, such as killing tumor cells, targeting, penetrating, and proliferating into the tumor. S. enterica has been genetically modified to ensure safety and increase its intrinsic antitumor efficacy. This bacterium has been used as a vector for delivering anticancer agents and as a combination therapy with chemotherapy, radiotherapy, or photothermic. Recent studies have reported the antitumor efficacy of outer membrane vesicles (OMVs) derived from S. enterica. OMVs are considered safer than attenuated bacteria and can stimulate the immune system as they comprise most of the immunogens found on the surface of their parent bacteria. Furthermore, OMVs can also be used as nanocarriers for antitumor agents. This review describes the advances in S. enterica as immunotherapy against cancer and the mechanisms by which Salmonella fights cancer. We also highlight the use of OMVs as immunotherapy and nanocarriers of anticancer agents. OMVs derived from S. enterica are innovative and promising strategies requiring further investigation.