Immune Responses Raised in an Experimental Colon Carcinoma Model Following Oral Administration of Lactobacillus casei

Mechanisms of primary and acquired resistance to PD-1/PD-L1 blockade and the emerging role of gut microbiome

As a very promising immunotherapy, PD-1/PD-L1 blockade has revolutionized the treatment of a variety of tumor types, resulting in significant clinical efficacy and lasting responses. However, these therapies do not work for a large proportion of patients initially, which is called primary resistance. And more frustrating is that most patients eventually develop acquired resistance after an initial response to PD-1/PD-L1 blockade. The mechanisms that lead to primary and acquired resistance to PD-1/PD-L1 inhibition have remained largely unclear. Recently, the gut microbiome has emerged as a potential regulator for PD-1/PD-L1 blockade. This review elaborates on the current understanding of the mechanisms in terms of PD-1 related signaling pathways and necessary factors. Moreover, this review discusses new strategies to increase the efficacy of immunotherapy from the perspectives of immune markers and gut microbiome.

Biogenic selenium nanoparticles produced by Lactobacillus casei ATCC 393 inhibit colon cancer cell growth in vitro and in vivo

Selenium compounds exhibit excellent anticancer properties but have a narrow therapeutic window. Selenium nanoparticles, however, are less toxic compared to other selenium forms, and their biogenic production leads to improved bioavailability. Herein, we used the probiotic strain Lactobacillus casei ATCC 393, previously shown to inhibit colon cancer cell growth, to synthesize biogenic selenium nanoparticles. We examined the anticancer activity of orally administered L. casei, L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei, and investigated their antitumor potential in the CT26 syngeneic colorectal cancer model in BALB/c mice. Our results indicate that L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei exert cancer-specific antiproliferative activity in vitro. Moreover, the nanoparticles were found to induce apoptosis and elevate reactive oxygen species levels in cancer cells. It is noteworthy that, when administered orally, selenium nanoparticle-enriched L. casei attenuated the growth of colon carcinoma in mice more effectively than the isolated nanoparticles or L. casei, suggesting a potential additive effect of the nanoparticles and the probiotic. To the best of our knowledge this is the first comparative study examining the anticancer effects of selenium nanoparticles synthesized by a microorganism, the selenium nanoparticle-enriched microorganism and the sole microorganism.

Drops of Lactiplantibacillus plantarum CRL 759 culture supernatant attenuates eyes inflammation induced by lipopolysaccharide

Anti-inflammatory effect of soluble secreted compounds of probiotic bacteria was widely demonstrated as therapy for different inflammatory diseases, but was not investigated in inflammatory eye disorders. The aim of this study was to determine whether Lactiplantibacillus plantarum CRL759 cell-free supernatant reduced inflammatory parameters and clinical signs in ocular inflammations. First, we evaluated the effect of L. plantarum CRL759 supernatant in vitro on human retinal cell line, ARPE-19 cells, stimulated with lipopolysaccharide (LPS). Then, we investigated in vivo its capacity to decrease inflammation by local administration on the eyes of mice with endotoxin induced inflammation. In vitro assays demonstrated that L. plantarum CRL759 supernatant reduced the production of interleukin (IL)-6, IL-8, nitric oxide and thiobarbituric acid reactive substances in LPS-stimulated ARPE-19 cells. Our in vivo data proved that L. plantarum supernatant significantly reduced the clinical score of endotoxin treated mice and diminished levels of tumour necrosis factor alpha, interferon gamma and protein concentration in aqueous humour. Histological examination showed reduction of infiltrating inflammatory cells in the posterior segment of the eyes. As far as we know, this is the first report showing that Lactobacillus spp. supernatant administered as drops reduces some parameters of ocular inflammation. This promising strategy is safe and could alleviate symptoms and signs of ocular inflammation in people that are refractories to the conventional therapies.

The role of gut microbiota in tumorigenesis and treatment

A large number of microbial communities exist in normal human intestinal tracts, which maintain a relatively stable dynamic balance under certain conditions. Gut microbiota are closely connected with human health and the occurrence of tumors. The colonization of certain intestinal bacteria on specific sites, gut microbiota disturbance and intestinal immune disorders can induce the occurrence of tumors. Meanwhile, gut microbiota can also play a role in tumor therapy by participating in immune regulation, influencing the efficacy of anti-tumor drugs, targeted therapy of engineered probiotics and fecal microbiota transplantation. This article reviews the role of gut microbiota in the occurrence, development, diagnosis and treatment of tumors. A better understanding of how gut microbiota affect tumors will help us find more therapies to treat the disease.

Pro-biomics: Omics Technologies To Unravel the Role of Probiotics in Health and Disease

The comprehensive characterization of probiotic action has flourished during the past few decades, alongside the evolution of high-throughput, multiomics platforms. The integration of these platforms into probiotic animal and human studies has provided valuable insights into the holistic effects of probiotic supplementation on intestinal and extraintestinal diseases. Indeed, these methodologies have informed about global molecular changes induced in the host and residing commensals at multiple levels, providing a bulk of metagenomic, transcriptomic, proteomic, and metabolomic data. The meaningful interpretation of generated data remains a challenge; however, the maturation of the field of systems biology and artificial intelligence has supported analysis of results. In this review article, we present current literature on the use of multiomics approaches in probiotic studies, we discuss current trends in probiotic research, and examine the possibility of tailor-made probiotic supplementation. Lastly, we delve deeper into newer technologies that have been developed in the last few years, such as single-cell multiomics analyses, and provide future directions for the maximization of probiotic efficacy.

Isolation of a Lactobacillus paracasei Strain with Probiotic Attributes from Kefir Grains

Κefir is a rich source of potentially probiotic bacteria. In the present study, firstly, in vitro screening for probiotic characteristics of ten lactic acid bacteria (LAB) isolated from kefir grains was performed. Strain AGR 4 was selected for further studies. Molecular characterization of strain AGR 4, confirmed that AGR 4 belongs to the Lactobacillus paracasei (reclassified to Lacticaseibacillus paracasei subsp. paracasei) species. Further testing revealed that L. paracasei AGR 4 displayed adhesion capacity on human adenocarcinoma cells, HT-29, similar to that of the reference strain, L. casei ATCC 393. In addition, the novel strain exerted significant time- and dose-dependent antiproliferative activity against HT-29 cells and human melanoma cell line, A375, as demonstrated by the sulforhodamine B cytotoxicity assay. Flow cytometry analysis was employed to investigate the mechanism of cellular death; however, it was found that AGR 4 did not act by inducing cell cycle arrest and/or apoptotic cell death. Taken together, these findings promote the probiotic character of the newly isolated strain L. paracasei AGR 4, while further studies are needed for the detailed description of its biological properties.

The inhibitory effects of probiotics on colon cancer cells: in vitro and in vivo studies

Background

Colorectal cancer (CRC) is the most common gastrointestinal malignancy. And probiotics may have the function of preventing colon cancer. The aim of this study was to investigate the inhibitory effects of a probiotic mixture on colorectal cancer and its potential mechanisms.

Methods

The effects of the probiotic mixture on proliferation and metastasis of mouse colon cancer CT26 cells were assessed by probiotics and cells co-culture assay, Cell Counting Kit-8 assay, colony formation assay, wound-healing assay, as well as migration and invasion assays. And CT26 cells were also transplanted into BALB/c mice to construct transplanted tumor animal model. The mice were randomly divided into two groups, control group and probiotic mixture intragastric administration group, after injection 21 days the tumor size and infiltration of immune cells in the tumor or spleen tissues were analyzed by hematoxylin and eosin (HE) and immunohistochemistry (IHC) staining.

Results

The probiotic mixture significantly inhibited the proliferation, invasion, and migration ability of CT26 cells compare to the control cells (P<0.05). In the animal experiments, the tumor volume of mice that had been fed the probiotic mixture was significantly smaller than that of the control group (P<0.05). Compared with control mice, more apoptotic cells and infiltration of immune cells were showed in the tumor tissues of the mice treated with the probiotic mixture, and an increased number of CD8+ cells in the tumor and spleen tissues but no significant change in tissues.

Conclusions

These results suggested that the probiotic mixture could inhibit the growth of CT26 tumors and induce an immune response in vivo. The probiotic mixture also inhibited the invasion, migration, and proliferation ability of CT26 cells in vitro.

Obligate and facultative anaerobic bacteria in targeted cancer therapy: Current strategies and clinical applications

Traditional methods for cancer therapy, including radiotherapy, chemotherapy, and immunotherapy are characterized by inherent limitations. Bacteria-mediated tumor therapy is becoming a promising approach in cancer treatment due to the ability of obligate or facultative anaerobic microorganisms to penetrate and proliferate in hypoxic regions of tumors. It is widely known that anaerobic bacteria cause the regression of tumors and inhibition of metastasis through a variety of mechanisms, including toxin production, anaerobic lifestyle and synergy with anti-cancer drugs. These features have the potential to be used as a supplement to conventional cancer treatment. To the best of our knowledge, no reports have been published regarding the most common tumor-targeting bacterial agents with special consideration of obligate anaerobes (such as Clostridium sp., Bifidobacterium sp.) and facultative anaerobes (including Salmonella sp., Listeria monocytogenes, Lactobacillus sp., Escherichia coli, Corynebacterium diphtheriae and Pseudomonas sp). In this review, we summarize the latest literature on the role of these bacteria in cancer treatment.

Modulation of Anti-Tumour Immune Responses by Probiotic Bacteria

There is a growing amount of evidence to support the beneficial role of a balanced intestinal microbiota, or distinct members thereof, in the manifestation and progression of malignant tumours, not only in the gastrointestinal tract but also in distant tissues as well. Intriguingly, bacterial species have been demonstrated to be indispensable modulatory agents of widely-used immunotherapeutic or chemotherapeutic regiments. However, the exact contribution of commensal bacteria to immunity, as well as to neoplasia formation and response to treatment, has not been fully elucidated, and most of the current knowledge acquired from animal models has yet to be translated to human subjects. Here, recent advances in understanding the interaction of gut microbes with the immune system and the modulation of protective immune responses to cancer, either naturally or in the context of widely-used treatments, are reviewed, along with the implications of these observations for future therapeutic approaches. In this regard, bacterial species capable of facilitating optimal immune responses against cancer have been surveyed. According to the findings summarized here, we suggest that strategies incorporating probiotic bacteria and/or modulation of the intestinal microbiota can be used as immune adjuvants, aiming to optimize the efficacy of cancer immunotherapies and conventional anti-tumour treatments.

Linking Obesity with Colorectal Cancer: Epidemiology and Mechanistic Insights

The incidence of obesity and colorectal cancer (CRC) has risen rapidly in recent decades. More than 650 million obese and 2 billion overweight individuals are currently living in the world. CRC is the third most common cancer. Obesity is regarded as one of the key environmental risk factors for the pathogenesis of CRC. In the present review, we mainly focus on the epidemiology of obesity and CRC in the world, the United States, and China. We also summarize the molecular mechanisms linking obesity to CRC in different aspects, including nutriology, adipokines and hormones, inflammation, gut microbiota, and bile acids. The unmet medical needs for obesity-related CRC are still remarkable. Understanding the molecular basis of these associations will help develop novel therapeutic targets and approaches for the treatment of obesity-related CRC.

Assessment of the Immunomodulatory Properties of the Probiotic Strain Lactobacillus paracasei K5 in vitro and In Vivo

Lactobacillus paracasei K5 is a lactic acid bacteria (LAB) strain that has been isolated from dairy products. Previous studies have established its probiotic potential in a series of in vitro tests, including molecular characterization, safety profiling, and tolerability of the gastrointestinal tract conditions. To characterize its beneficial actions on the host, we have shown previously that L. paracasei K5 adheres to Caco-2 cells and exerts anti-proliferative effects through the induction of apoptosis. In the present study, we focused on the immunomodulatory potential of this strain. We employed the dorsal-air-pouch mouse model of inflammation and recorded an eight-fold increase in the recruitment of immune cells in mice treated with the probiotic strain, compared to the control group. Analysis of the exudates revealed significant changes in the expression of pro-inflammatory mediators on site. Treatment of Caco-2 cells with L. paracasei K5 induced significant upregulation of cytokines interleukin-1α (IL-1α), ΙL-1β, IL-6, tumor necrosis factor-alpha (TNF-α), the chemokine C-X-C motif ligand 2 (CXCL2), and the inflammation markers soluble intercellular adhesion molecule (sICAM) and metallopeptidase inhibitor-1 (TIMP-1). Transient induction of the Toll-like receptors (TLRs) 2, 4, 6, and 9 expression levels was recorded by real-time PCR analysis. These results highlight the immunomodulatory potential of this strain and further support its probiotic character.