Antibiotics treatment promotes vasculogenesis in the brain of glioma-bearing mice

Gut microbiota and their influence in brain cancer milieu

Microbial communities are not simply remnants of the past but dynamic entities that continuously evolve under the selective pressures of nature, reflecting the intricate and adaptive processes of evolution. The microbiota residing in the various regions of the human body has numerous roles in different physiological processes such as nutrition, metabolism, immune regulation, etc. In the zeal of achieving empirical insights into the ambit of the gut microbiome, the research over the years led to the revelation of reciprocal interaction between the gut microbiome and the cognitive functioning of the human body. Dysbiosis in the gut microbial composition disturbs the homeostatic cognitive functioning of the human body. This dysbiosis has been associated with various chronic diseases, including brain cancer, such as glioma, glioblastoma, etc. This review explores the mechanistic role of dysbiosis-mediated progression of brain cancers and their subtypes. Moreover, it demonstrates the regulatory role of microbial metabolites produced by the gut microbiota, such as short-chain fatty acids, amino acids, lipids, etc., in the tumour progression. Further, we also provide valuable insights into the microbiota mediating the efficiency of therapeutic regimens, thereby leveraging gut microbiota as potential biomarkers and targets for improved treatment outcomes.

Exploring the Microbiome's Impact on Glioma and Brain Metastases: Insights into Development, Progression, and Treatment Response-A Scoping Review

Background: The human microbiome plays a crucial role in health and disease. Dysbiosis, an imbalance of microorganisms, has been implicated in cancer development and treatment response, including in primary brain tumors and brain metastases, through interactions mediated by the gut-brain axis. This scoping review synthesizes current evidence on the relationship between the human microbiome and brain tumors. Methods: A systematic search of five electronic databases was conducted by an expert librarian, using controlled vocabulary and keywords. A targeted grey literature search in Google Scholar and clinical trial registries was also undertaken. Eligible studies included primary research involving human patients, or in vivo, or in vitro models of glioma or brain metastasis, with a focus on the microbiome's role in tumor development, treatment response, and outcomes. Results: Out of 584 citations screened, 40 studies met inclusion criteria, comprising 24 articles and 16 conference abstracts. These included 12 human studies, 16 using mouse models, 7 combining both, and 5 employing large datasets or next-generation sequencing of tumor samples. Thirty-one studies focused on primary brain tumors, six on brain metastases, and three on both. Of the 20 studies examining dysbiosis in tumor development, 95% (n = 19) found an association with tumor growth. Additionally, 71.4% (n = 5/7) of studies reported that microbiome alterations influenced treatment efficacy. Conclusions: Although the role of the gut-brain axis in brain tumors is still emerging and is characterized by heterogeneity across studies, existing evidence consistently supports a relationship between the gut microbiome and both brain tumor development and treatment outcomes.

Targeting gut microbiota: a potential therapeutic approach for tumor microenvironment in glioma

Glioma, being one of the malignant tumors with the highest mortality rate globally, has an unclear pathogenesis, and the existing treatment effects still have certain limitations. The tumor microenvironment (TME) plays an important role in the occurrence, development, and recurrence of glioma. As one of the important regulatory factors of TME, the gut microbiota can regulate the progression of glioma not only by interacting with the brain through the brain-gut axis but also by influencing the tumor immune microenvironment (TIME) and inflammatory microenvironment. Recent studies have identified the gut microbiota and TME as potential therapeutic targets for glioma. This paper aims to summarize the role of the gut microbiota in TME, the association between them and glioma, and the potential of developing new intervention measures by targeting the gut microbiota. Understanding the involvement process of the gut microbiota in glioma may pave the way for the development of effective treatment methods that can regulate TME and prevent disease progression.

Exploiting the gut microbiome for brain tumour treatment

Increasing evidence suggests that the gut microbiome plays a key role in a host of pathological conditions, including cancer. Indeed, the bidirectional communication that occurs between the gut and the brain, known as the 'gut-brain axis,' has recently been implicated in brain tumour pathology. Here, we focus on current research that supports a gut microbiome-brain tumour link with emphasis on high-grade gliomas, the most aggressive of all brain tumours, and the impact on the glioma tumour microenvironment. We discuss the potential use of gut-brain axis signals to improve responses to current and future therapeutic approaches. We highlight that the success of novel treatment strategies may rely on patient-specific microbiome profiles, and these should be considered for personalised treatment approaches.

The Role of Bacteria in Central Nervous System Tumors: Opportunities and Challenges

Tumors of the central nervous system (CNS) are severe and refractory diseases with poor prognosis, especially for patients with malignant glioblastoma and brain metastases. Currently, numerous studies have explored the potential role of bacteria and intestinal flora in tumor development and treatment. Bacteria can penetrate the blood-brain barrier (BBB), targeting the hypoxic microenvironment at the core of tumors, thereby eliminating tumors and activating both the innate and adaptive immune responses, rendering them promising therapeutic agents for CNS tumors. In addition, engineered bacteria and derivatives, such as bacterial membrane proteins and bacterial spores, can also be used as good candidate carriers for targeted drug delivery. Moreover, the intestinal flora can regulate CNS tumor metabolism and influence the immune microenvironment through the "gut-brain axis". Therefore, bacterial anti-tumor therapy, engineered bacterial targeted drug delivery, and intervention of the intestinal flora provide therapeutic modalities for the treatment of CNS tumors. In this paper, we performed a comprehensive review of the mechanisms and therapeutic practices of bacterial therapy for CNS tumors and discussed potential future research directions in this field.

Effect of antibiotic drug use on outcome and therapy-related toxicity in patients with glioblastoma-A retrospective cohort study

Background

Glioblastoma (GB) is the most frequent malignant brain tumor and has a dismal prognosis. In other cancers, antibiotic use has been associated with severity of chemotherapy-induced toxicity and outcome. We investigated if these mechanisms are also involved in GB.

Methods

We selected a cohort of 78 GB patients who received combined radiochemotherapy. We investigated if exposure to prediagnostic antibiotic use is associated with clinical side effects and laboratory changes during adjuvant therapy as well as overall survival (OS) and progression-free survival (PFS) using chi-square test, binary logistic regression, Kaplan-Meyer analysis, and multivariable Cox regression.

Results

Seventeen patients (21.8%) received at least one course of prediagnostic antibiotics and 61 (78.2%) received no antibiotics. We found a higher incidence of loss of appetite (23.5% vs. 4.9%; P = .018) and myelosuppression (41.2% vs. 18.0%; P = .045) in the antibiotic group. Multivariable logistic regression analysis revealed antibiotics to be a predictor for nausea (OR = 6.94, 95% CI: 1.09-44.30; P = .041) and myelosuppression (OR = 9.75, 95% CI: 1.55-61.18; P = .015). Furthermore, lymphocytopenia was more frequent in the antibiotic group (90.0% vs. 56.1%, P = .033). There were no significant differences in OS (P = .404) and PFS (P = .844). Multivariable Cox regression showed a trend toward shorter survival time (P = .089) in the antibiotic group.

Conclusions

Our study suggests that antibiotic use affects symptoms and lab values in GB patients. Larger prospective studies are required to investigate if prediagnostic antibiotic use could be a prognostic factor in GB patients.