Microbiota Manipulation by Probiotics Administration as Emerging Tool in Cancer Prevention and Therapy

The effect of oral probiotics on response to vaccination in older adults: a systematic review of randomised controlled trials

This systematic review evaluated the impact of oral probiotics on the immune response to vaccination in older people. A literature search was performed in three electronic databases up to January 2023. Randomised controlled trials (RCTs) conducted in older people (age ≥ 60 years) investigating oral probiotics and vaccine response outcomes were included. Characteristics and outcome data of the included studies were extracted and analysed and study quality was assessed using the Cochrane Risk of Bias Tool for randomised trials. Ten RCTs involving 1,560 participants, reported in 9 papers, were included. Nine studies involved the seasonal influenza vaccine and one a COVID-19 vaccine. All studies used lactobacilli, some in combination with bifidobacteria. Studies reported outcomes including anti-vaccine antibody titres or concentrations, seroconversion and seroprotection. When comparing antibody titres, seroprotection rate and seroconversion rate between probiotic and placebo groups expressed as a response ratio, the weighted mean values were 1.29, 1.16 and 2.00, respectively. Meta-analysis showed that probiotics increase seroconversion rates to all three strains of the seasonal influenza vaccine: odds ratio (95% confidence interval) 2.74 (1.31, 5.70; P = 0.007) for the H1N1 strain; 1.90 (1.04, 3.44; P = 0.04) for the H3N2 strain; 1.72 (1.05, 2.80; P = 0.03) for the B strain. There was a low level of heterogeneity in these findings. Several studies were at high risk of bias due to missing outcome data. Lactobacilli may improve the vaccine response, but further research is needed to be more certain of this.

A Review of the Use of Native and Engineered Probiotics for Colorectal Cancer Therapy

Colorectal cancer (CRC) is a serious global health concern, and researchers have been investigating different strategies to prevent, treat, or support conventional therapies for CRC. This review article comprehensively covers CRC therapy involving wild-type bacteria, including probiotics and oncolytic bacteria as well as genetically modified bacteria. Given the close relationship between CRC and the gut microbiota, it is crucial to compile and present a comprehensive overview of bacterial therapies used in the context of colorectal cancer. It is evident that the use of native and engineered probiotics for colorectal cancer therapy necessitates research focused on enhancing the therapeutic properties of probiotic strains.. Genetically engineered probiotics might be designed to produce particular molecules or to target cancer cells more effectively and cure CRC patients.

Gut microbiota and its therapeutic implications in tumor microenvironment interactions

The development of cancer is not just the growth and proliferation of a single transformed cell, but its tumor microenvironment (TME) also coevolves with it, which is primarily involved in tumor initiation, development, metastasis, and therapeutic responses. Recent years, TME has been emerged as a potential target for cancer diagnosis and treatment. However, the clinical efficacy of treatments targeting the TME, especially its specific components, remains insufficient. In parallel, the gut microbiome is an essential TME component that is crucial in cancer immunotherapy. Thus, assessing and constructing frameworks between the gut microbiota and the TME can significantly enhance the exploration of effective treatment strategies for various tumors. In this review the role of the gut microbiota in human cancers, including its function and relationship with various tumors was summarized. In addition, the interaction between the gut microbiota and the TME as well as its potential applications in cancer therapeutics was described. Furthermore, it was summarized that fecal microbiota transplantation, dietary adjustments, and synthetic biology to introduce gut microbiota-based medical technologies for cancer treatment. This review provides a comprehensive summary for uncovering the mechanism underlying the effects of the gut microbiota on the TME and lays a foundation for the development of personalized medicine in further studies.

The nasopharyngeal microbiome in COVID-19

The development of novel culture-independent techniques of microbial identification has allowed a rapid progress in the knowledge of the nasopharyngeal microbiota and its role in health and disease. Thus, it has been demonstrated that the nasopharyngeal microbiota defends the host from invading pathogens that enter the body through the upper airways by participating in the modulation of innate and adaptive immune responses. The current COVID-19 pandemic has created an urgent need for fast-track research, especially to identify and characterize biomarkers to predict the disease severity and outcome. Since the nasopharyngeal microbiota diversity and composition could potentially be used as a prognosis biomarker for COVID-19 patients, which would pave the way for strategies aiming to reduce the disease severity by modifying such microbiota, dozens of research articles have already explored the possible associations between changes in the nasopharyngeal microbiota and the severity or outcome of COVID-19 patients. Unfortunately, results are controversial, as many studies with apparently similar experimental designs have reported contradictory data. Herein we put together, compare, and discuss all the relevant results on this issue reported to date. Even more interesting, we discuss in detail which are the limitations of these studies, that probably are the main sources of the high variability observed. Therefore, this work is useful not only for people interested in current knowledge about the relationship between the nasopharyngeal microbiota and COVID-19, but also for researchers who want to go further in this field while avoiding the limitations and variability of previous works.

The progress on the relationship between gut microbiota and immune checkpoint blockade in tumors

Immune checkpoint blockade (ICB) has emerged as a promising immunotherapeutic approach for the treatment of various tumors. However, the efficacy of this therapy is limited in a subset of patients, and it is important to develop strategies to enhance immune responses. Studies have demonstrated a critical role of gut microbiota in regulating the therapeutic response to ICB. Gut microbiota composition, diversity, and function are mediated by metabolites, such as short-chain fatty acids and secondary bile acids, that interact with host immune cells through specific receptors. In addition, gut bacteria may translocate to the tumor site and stimulate antitumor immune responses. Therefore, maintaining a healthy gut microbiota composition, for instance through avoiding the use of antibiotics or probiotic interventions, can be an effective approach to optimize ICB therapy. This review summarizes the current understanding of the microbiota-immunity interactions in the context of ICB therapy, and discusses potential clinical implications of these findings.

Lacticaseibacillus rhamnosus Probio-M9 enhanced the antitumor response to anti-PD-1 therapy by modulating intestinal metabolites

BACKGROUND

Probiotics have been increasingly proposed for enhancing immune checkpoint blockade (ICB) treatments against cancer. However, its causal relationship with immunotherapeutic efficacy remains unclear, which promoted us to explore if and how probiotic Lacticaseibacillus rhamnosus Probio-M9 manipulates gut microbiome for expected outcomes.

METHODS

We evaluated the effects of Probio-M9 on the anti-PD-1 treatment against colorectal cancer in mice via a multi-omics approach. We defined the mechanisms of Probio-M9-mediated antitumor immunity by comprehensive analyses of metagenome and metabolites of commensal gut microbes as well as the immunologic factors and serum metabolome of the host.

FINDINGS

The results indicated that Probio-M9 intervention strengthened the anti-PD-1-based tumor inhibition. Both prophylactic and therapeutic administration of Probio-M9 showed conspicuous performance in controlling tumor growth with ICB treatment. The supplement of Probio-M9 modulated enhanced immunotherapy response through promoting beneficial microbes (e.g., Lactobacillus and Bifidobacterium animalis), producing beneficial metabolites including butyric acids in the gut, and accumulating blood-derived α-ketoglutaric acid, N-acetyl-l-glutamic acid and pyridoxine in particular, which promoted the infiltration and activation of cytotoxic T lymphocytes (CTLs) and suppressing the function of regulatory T cells (Tregs) in the tumor microenvironment (TME). Subsequently, we found that enhanced immunotherapeutic response was transmissible by transplanting either post-probiotic-treatment gut microbes or intestinal metabolites to new tumor-bearing mice.

INTERPRETATION

This study offered valuable insight into the causal role of Probio-M9 in correcting the defects in gut microbiota that compromised anti-PD-1 therapeutic efficacy, which can be used as an alternative synergetic agent with ICB for clinical cancer treatment.

FUNDING

This research was supported by Research Fund for the National Key R&D Program of China (2022YFD2100702), Inner Mongolia Science and Technology Major Projects (2021ZD0014), and China Agriculture Research System of MOF and MARA.

Pterostilbene and Probiotic Complex in Chemoprevention of Putative Precursor Lesions for Colorectal Cancer in an Experimental Model of Intestinal Carcinogenesis with 1,2-Dimethylhydrazine

Dietary supplementation with pterostilbene (PS) and/or a probiotic (PRO) may ameliorate the intestinal microbiota in disease conditions. This study aims to evaluate PS and PRO for the chemoprevention of putative precursor lesions for colorectal cancer (CRC) in an experimental model of intestinal carcinogenesis with 1,2-dimethylhydrazine (1,2-DMH). Sixty male Wistar rats were equally divided into five groups: Sham, 1,2-DMH, 1,2-DMH + PS, 1,2-DMH + PRO, and 1,2-DMH + PS + PRO. PRO (5 × 10⁷/mL) was offered in water, and PS (300 ppm) was provided in the diet ad libitum. 1,2-DMH (20 mg/kg/week) was administered for 15 consecutive weeks. In the 25th week, proctocolectomy was conducted. PRO alone and PRO combined with PS were the best intervention strategies to improve experimental 1,2-DMH-induced CRC regarding several parameters of carcinogenesis. Our findings may contribute to the development of novel preventive strategies for CRC and may help to identify novel modulators of colon carcinogenesis.

Cell-free Lactiplantibacillus plantarum OC01 supernatant suppresses IL-6-induced proliferation and invasion of human colorectal cancer cells: Effect on β-Catenin degradation and induction of autophagy

Background and aim

Gut microbiota is considered as a complex organ of human body. The interaction between the host and microbiota is dynamic and controlled by a huge number of factors, such as lifestyle, geography, pharmaceuticals, diet, and stress. The breakdown of this relationship could change microbiota composition favoring the onset of several diseases, including cancer. Metabolites released by microbiota bacterial strains have been reported to elicit protective effects on the mucosa that could contrast cancer development and progression. Here, we tested the ability of specific probiotic strain Lactiplantibacillus plantarum OC01-derived metabolites (NCIMB 30624) to contrast the malignant features of colorectal cancer (CRC) cells.

Experimental procedure

The study was performed on two cell lines, HCT116 and HT29, cultured in 2D and 3D, and focused on the hallmarks of cell proliferation and migration.

Results and conclusion

Probiotic metabolites reduced cell proliferation both in 2D and 3D-spheroid cultures, the latter model mimicking the growth in vivo. The bacterial metabolites also contrasted the pro-growth and pro-migratory activity of inteurleukin-6 (IL-6), an inflammatory cytokine abundantly found in the tumor microenvironment of CRC. These effects were associated with inhibition of the ERK and of the mTOR/p70S6k pathways and with the inhibition of the E-to N-Cadherin switch. In a parallel study, we found that sodium butyrate (a representative of the main probiotic metabolites) induced autophagy and β-Catenin degradation, which is consistent with the growth inhibitory activity. The present data indicate that the metabolites of Lactiplantibacillus plantarum OC01 (NCIMB 30624) elicits anti-tumor effect and support its possible inclusion as adjuvant therapy of CRC for limiting cancer growth and progression.

Probiotic Supplementation Suppresses Tumor Growth in an Experimental Colorectal Cancer Liver Metastasis Model

Colorectal cancer (CRC) ranks third in incidence and second in mortality of all cancers worldwide. At the time of primary diagnosis, around 20% of patients already have metastatic CRC and only around 20% are candidates for radical resection. Thus, most of the patients have to undergo chemotherapy (CTx). Due to chemoresistance and side effects, novel treatment additives are crucial for controlling the disease and prolonging patient survival. The aim of this study was to evaluate probiotic supplementation and its antitumorigenic effects in an experimental CRC liver metastasis model. Six-week-old male Wistar rats received either a multispecies probiotic (1.2 × 10⁹ CFU/daily) or placebo mixture. On day 14 of the experiment, rat CRC cells (CC531) were implanted under the liver capsule later treated by FOLFOX CTx. Change in tumor volume was measured by performing micro computed tomography (micro-CT) scanning on experimental days 28 and 34. Additionally, immunohistochemical staining with anti-MPO, anti-Ki67, and anti-CD31 were performed. Tumor apoptosis was evaluated using TUNEL staining. Micro-CT image analysis indicates that probiotic supplementation significantly inhibits tumor growth. No synergistic effects between probiotic supplementation and FOLFOX CTx was observed. Reduced tumor volume was achieved by inhibiting angiogenesis, as tumor microvascular density was significantly lower in rats receiving probiotic supplementation. This study shows that a multispecies probiotic mixture significantly reduces angiogenesis and inhibits CRC liver metastasis growth in an experimental rat model.

Biodetoxification and Protective Properties of Probiotics

Probiotic consumption is recognized as being generally safe and correlates with multiple and valuable health benefits. However, the mechanism by which it helps detoxify the body and its anti-carcinogenic and antimutagenic potential is less discussed. A widely known fact is that globalization and mass food production/cultivation make it impossible to keep all possible risks under control. Scientists associate the multitude of diseases in the days when we live with these risks that threaten the population’s safety in terms of food. This review aims to explore whether the use of probiotics may be a safe, economically viable, and versatile tool in biodetoxification despite the numerous risks associated with food and the limited possibility to evaluate the contaminants. Based on scientific data, this paper focuses on the aspects mentioned above and demonstrates the probiotics’ possible risks, as well as their anti-carcinogenic and antimutagenic potential. After reviewing the probiotic capacity to react with pathogens, fungi infection, mycotoxins, acrylamide toxicity, benzopyrene, and heavy metals, we can conclude that the specific probiotic strain and probiotic combinations bring significant health outcomes. Furthermore, the biodetoxification maximization process can be performed using probiotic-bioactive compound association.

Probiotics, Prebiotics and Postbiotics on Mitigation of Depression Symptoms: Modulation of the Brain-Gut-Microbiome Axis

The brain–gut–microbiome axis is a bidirectional communication pathway between the gut microbiota and the central nervous system. The growing interest in the gut microbiota and mechanisms of its interaction with the brain has contributed to the considerable attention given to the potential use of probiotics, prebiotics and postbiotics in the prevention and treatment of depressive disorders. This review discusses the up-to-date findings in preclinical and clinical trials regarding the use of pro-, pre- and postbiotics in depressive disorders. Studies in rodent models of depression show that some of them inhibit inflammation, decrease corticosterone level and change the level of neurometabolites, which consequently lead to mitigation of the symptoms of depression. Moreover, certain clinical studies have indicated improvement in mood as well as changes in biochemical parameters in patients suffering from depressive disorders.

Probiotic Streptococcus salivarius K12 Alleviates Radiation-Induced Oral Mucositis in Mice

Background

Oral mucositis is the most common oral complication of cancer patients receiving radiotherapy and/or chemotherapy, leading to poor quality of life. Limitations of the current interventions on radiation-induced oral mucositis (RIOM) urge the development of novel therapeutics. Here, we evaluated the treatment outcome of probiotic Streptococcus salivarius K12 on RIOM mice, and oral microbiota that is associated with the progress of RIOM was further investigated.

Methods

An experimental RIOM mouse model was established, and S. salivarius K12 was applied to the mouse oral cavity daily. Histological analyses were performed to evaluate the severity of oral mucositis and the treatment outcome of S. salivarius K12. The oral microbiota of mice was further analyzed by 16S rRNA sequencing, microbial culture and qPCR.

Results

Irradiation induced conspicuous mucositis in the oral cavity of mice. S. salivarius K12 treatment was beneficial for the healing of RIOM, as reflected by reduced ulcer size, increased basal layer epithelial cellularity and mucosal thickness, and elevated epithelial proliferation and attenuated apoptosis. RIOM mice presented significant oral microbial dysbiosis, with an overgrowth of oral anaerobes. S. salivarius K12 treatment reconstituted the oral microbiota and decreased the abundance of oral anaerobes of RIOM mice. In addition, S. salivarius K12 treatment inhibited NI1060 in Pasteurella genus and downregulated the expression of nitrate reductase.

Conclusions

S. salivarius K12 treatment can alleviate RIOM and reconstituted the dysbiotic oral microbiota in mice. S. salivarius K12 may represent a promising adjuvant treatment to improve the quality of life of cancer patients receiving radiotherapy.

Investigation of Nasal/Oropharyngeal Microbial Community of COVID-19 Patients by 16S rDNA Sequencing

Since December 2019, SARS-CoV-2 infection has been still rapidly spreading, resulting in a pandemic, followed by an increasing number of cases in countries throughout the world. The severity of the disease depends on the patient's overall medical condition but no appropriate markers are available to establish the prognosis of the patients. We performed a 16S rRNA gene sequencing, revealing an altered composition of the nasal/oropharyngeal (NOP) microbiota in 21 patients affected by COVID-19, paucisymptomatic or in an Intensive Care Unit (ICU), as compared to 10 controls negative for COVID-19 or eight affected by a different Human Coronavirus (HKU, NL63 and OC43). A significant decrease in Chao1 index was observed when patients affected by COVID-19 (in ICU) were compared to paucisymptomatic. Furthermore, patients who were in ICU, paucisymptomatic or affected by other Coronaviruses all displayed a decrease in the Chao1 index when compared to controls, while Shannon index significantly decreased only in patients under ICU as compared to controls and paucisymptomatic patients. At the phylum level, Deinococcus-Thermus was present only in controls as compared to SARS-CoV-2 patients admitted to ICU, paucisymptomatic or affected by other coronaviruses. Candidatus Saccharibacteria (formerly known as TM7) was strongly increased in negative controls and SARS-CoV-2 paucisymptomatic patients as compared to SARS-CoV-2 ICU patients. Other modifications were observed at a lower taxonomy level. Complete depletion of Bifidobacterium and Clostridium was exclusively observed in ICU SARS-CoV-2 patients, which was the only group characterized by the presence of Salmonella, Scardovia, Serratia and Pectobacteriaceae. In conclusion, our preliminary results showed that nasal/oropharyngeal microbiota profiles of patients affected with SARS-CoV-2 may provide valuable information in order to facilitate the stratification of patients and may open the way to new interventional strategies in order to ameliorate the outcome of the patients.