Gut Microbiota Modulate CD8 T Cell Responses to Influence Colitis-Associated Tumorigenesis

Microbiota-Gut-Brain Axis Regulation of Adult Hippocampal Neurogenesis

The birth, maturation, and integration of new neurons in the adult hippocampus regulates specific learning and memory processes, responses to stress, and antidepressant treatment efficacy. This process of adult hippocampal neurogenesis is sensitive to environmental stimuli, including peripheral signals from certain cytokines, hormones, and metabolites, which can promote or hinder the production and survival of new hippocampal neurons. The trillions of microorganisms resident to the gastrointestinal tract and collectively known as the gut microbiota, also demonstrate the ability to modulate adult hippocampal neurogenesis. In doing so, the microbiota-gut-brain axis can influence brain functions regulated by adult hippocampal neurogenesis. Unlike the hippocampus, the gut microbiota is highly accessible to direct interventions, such as prebiotics, probiotics, and antibiotics, and can be manipulated by lifestyle choices including diet. Therefore, understanding the pathways by which the gut microbiota shapes hippocampal neurogenesis may reveal novel targets for non-invasive therapeutics to treat disorders in which alterations in hippocampal neurogenesis have been implicated. This review first outlines the factors which influence both the gut microbiome and adult hippocampal neurogenesis, with cognizance that these effects might happen either independently or due to microbiota-driven mechanisms. We then highlight approaches for investigating the regulation of adult hippocampal neurogenesis by the microbiota-gut-brain axis. Finally, we summarize the current evidence demonstrating the gut microbiota’s ability to influence adult hippocampal neurogenesis, including mechanisms driven through immune pathways, microbial metabolites, endocrine signalling, and the nervous system, and postulate implications for these effects in disease onset and treatment.

The complex immunological role of Helicobacter in modulating cancer

The gut microbiota has recently emerged as a unique mechanism of immunotherapeutic resistance or response within certain cancer patients. Certain adherent bacterial species that reside along the epithelial barrier within the gastrointestinal tract have been shown to be the most immunogenic and include several species within the Helicobacteraceae family. The role of these microbes in cancer remains controversial and varies according to species, immune status, and cancer type. Here, we hypothesize that the functional characteristics rather than the bacterial species of Helicobacteraceae dictate the type of immune response with either a benefit or a detriment to overall cancer progression.

Interaction of Gut Microbiota with Endocrine Homeostasis and Thyroid Cancer

The gut microbiota plays a crucial role in healthy individuals as well as in patients with thyroid diseases, including thyroid cancer. Although the prognosis of differentiated thyroid cancer is predictable, that of some poorly differentiated, medullary, and anaplastic thyroid cancers remains unpromising. As the interaction between the gut microbiota and thyroid cancer has been gradually revealed in recent years, the thyroid gland, a crucial endocrine organ, is shown to have a complex connection with the body's metabolism and is involved in inflammation, autoimmunity, or cancer progression. Dysbiosis of the gut microbiota and its metabolites can influence changes in hormone levels and susceptibility to thyroid cancer through multiple pathways. In this review, we focus on the interactions of the gut microbiota with thyroid function diseases and thyroid cancer. In addition, we also discuss some potential new strategies for the prevention and treatment of thyroid disease and thyroid cancer. Our aim is to provide some possible clinical applications of gut microbiota markers for early diagnosis, treatment, and postoperative management of thyroid cancer. These findings were used to establish a better multi-disciplinary treatment and prevention management strategy and to individualize the treatment of patients in relation to their gut microbiota composition and pathological characteristics.

Association of Gut Microbiota with Inflammatory Bowel Disease and COVID-19 Severity: A Possible Outcome of the Altered Immune Response

Inflammatory bowel disease could be induced by SARS-CoV-2, involved in alteration of gut microbiota during the respiratory viral infection. Presence of viral RNA in fecal samples for longer period, even after the clearance of the virus from respiratory tract, is suggestive of dysbiosis leading to the poor prognosis of COVID-19 in hospitalized patients. Gut microbiome (GM) plays a significant role to stimulate the modulated antiviral immune response against invading pathogens regulating the physiological homeostasis. GM profile of COVID-19 patients has revealed the drastic depletion of dominant families of commensals in the gut such as, Bacteroidaceae, Lachnospiraceae and Ruminococcaceae to be replaced with Enterococcus, Staphylococcus, Streptococcus, Serratia etc. Immune dysfunction of Th1–Th17 cells along gut-lung axis impairs the mucosal lining translocating the microorganisms including commensals and metabolites to other body organs like lungs, brain, kidney through circulation. These events may cause hyper inflammations associated with excessive secretion of cytokines and chemokines to form the cytokine storm causing ARDS. Gut virome could interact with microbiome and immune cells, help establishing the antiviral immune signaling, important for health maintenance/ or in disease progression. Essentially, these immunological strategies are needed to use in future prospective therapeutics to control the severity events.

Immunomodulation by Gut Microbiome on Gastrointestinal Cancers: Focusing on Colorectal Cancer

Simple Summary

A symbiotic relationship with the host gut microbiome influences the immune system’s development, functions, and activities. In the mucosa, the gut microbiome mediates several immune activities such as the induction of naïve T-cells differentiation, production of cytokines, and myeloid cells activation. The gut-immune interaction and GI cancer development were investigated more recently. Understanding the interaction’s underlying mechanism provides insight to use them as potential anti-cancer targets. Even though multiple reports support the role of gut-immune interactions in targeting cancer-related pathways such as inflammation, apoptosis, and cellular proliferation, efforts are required to assess their interaction and impact on current treatment options.

Abstract

Gastrointestinal cancer (GI) is a global health disease with a huge burden on a patient’s physical and psychological aspects of life and on health care providers. It is associated with multiple disease related challenges which can alter the patient’s quality of life and well-being. GI cancer development is influenced by multiple factors such as diet, infection, environment, and genetics. Although activating immune pathways and components during cancer is critical for the host’s survival, cancerous cells can target those pathways to escape and survive. As the gut microbiome influences the development and function of the immune system, research is conducted to investigate the gut microbiome–immune interactions, the underlying mechanisms, and how they reduce the risk of GI cancer. This review addresses and summarizes the current knowledge on the major immune cells and gut microbiome interactions. Additionally, it highlights the underlying mechanisms of immune dysregulation caused by gut microbiota on four major cancerous pathways, inflammation, cellular proliferation, apoptosis, and metastasis. Overall, gut-immune interactions might be a key to understanding GI cancer development, but further research is needed for more detailed clarification.

The Potential of Gut Microbiota Metabolic Capability to Detect Drug Response in Rheumatoid Arthritis Patients

Gut microbiota plays an essential role in the development of rheumatoid arthritis (RA) and affects drug responses. However, the underlying mechanism remains elusive and urgent to elucidate to explore the pathology and clinical treatment of RA. Therefore, we selected methotrexate (MTX) as an example of RA drugs to explore the interactions between the gut microbiota and drug responses and obtain an in-depth understanding of their correlation from the perspective of the metabolic capability of gut microbiota on drug metabolism. We identified 2,654 proteins and the corresponding genes involved in MTX metabolism and then profiled their abundances in the gut microbiome datasets of four cohorts. We found that the gut microbiota harbored various genes involved in MTX metabolism in healthy individuals and RA patients. Interestingly, the number of genes involved in MTX metabolism was not significantly different between response (R) and non-response (NR) groups to MTX, but the gene composition in the microbial communities significantly differed between these two groups. Particularly, several models were built based on clinical information, as well as data on the gene, taxonomical, and functional biomarkers by using the random forest algorithm and then validated. Our findings provide bases for clinical management not only of RA but also other gut microbiome–related diseases. First, it suggests that the potential metabolic capability of gut microbiota on drug metabolism is important because they affect drug efficiency; as such, clinical treatment strategies should incorporate the gene compositions of gut microbial communities, in particular genes involved in drug metabolism. Second, a suitable model can be developed to determine hosts’ responses to drugs before clinical treatment.

Insights into the Role of Commensal-Specific T Cells in Intestinal Inflammation

Trillions of microorganisms exist in the human intestine as commensals and contribute to homeostasis through their interactions with the immune system. In this review, we use previous evidence from published papers to elucidate the involvement of commensal-specific T cells (CSTCs) in regulating intestinal inflammatory responses. CSTCs are generated centrally in the thymus or peripherally at mucosal interfaces and present as CD4+ or CD8+ T cells. Bacteria, fungi, and even viruses act commensally with humans, warranting consideration of CSTCs in this critical relationship. Dysregulation of this immunological balance can result in both intestinal inflammation or damaging autoimmune responses elsewhere in the body. Given the relative novelty of CSTCs in the literature, we aim to introduce the importance of their role in maintaining immune homeostasis at barrier sites such as the intestine.

Regulation of tissue-resident memory T cells by the Microbiota

Resident memory T cells (Trms) predominantly reside within tissue and are critical for providing rapid protection against invasive viruses, fungi and bacteria. Given that tissues are heavily impacted and shaped by the microbiota, it stands to reason that Trms are also influenced by the microbiota that inhabits barrier sites. The influence of the microbiota is largely mediated by microbial production of metabolites which are crucial to the immune response to both viral infection and cancerous tumors. In addition to the effects of metabolites, antigens derived from the microbiota can activate T cell responses. While microbiota-specific T cells may assist in tissue repair, control of infection and anti-tumor immunity, the actual 'memory' potential of these cells remains unclear. Here, we hypothesize that memory responses to antigens from the microbiota must be 'licensed' by inflammatory signals activated by invasion of the host by microorganisms.

Metabolic programs tailor T cell immunity in viral infection, cancer, and aging

Productive T cell responses to infection and cancer rely on coordinated metabolic reprogramming and epigenetic remodeling among the immune cells. In particular, T cell effector and memory differentiation, exhaustion, and senescence/aging are tightly regulated by the metabolism-epigenetics axis. In this review, we summarize recent advances of how metabolic circuits combined with epigenetic changes dictate T cell fate decisions and shape their functional states. We also discuss how the metabolic-epigenetic axis orchestrates T cell exhaustion and explore how physiological factors, such as diet, gut microbiota, and the circadian clock, are integrated in shaping T cell epigenetic modifications and functionality. Furthermore, we summarize key features of the senescent/aged T cells and discuss how to ameliorate vaccination- and COVID-induced T cell dysfunctions by metabolic modulations. An in-depth understanding of the unexplored links between cellular metabolism and epigenetic modifications in various physiological or pathological contexts has the potential to uncover novel therapeutic strategies for fine-tuning T cell immunity.

Transfer of Tumor-Bearing Mice Intestinal Flora Can Ameliorate Cognition in Alzheimer's Disease Mice

BACKGROUND

Fecal microbiota transplant (FMT) is a potential treatment approach for many diseases. Alzheimer's disease (AD) and cancer have been proven to have a specific antagonistic relationship to FMT.

OBJECTIVE

This article aims to explore whether intestinal flora transplantation from cancer individuals can ameliorate cognitive impairment.

METHODS

Morris water maze and object recognition tests were performed to assess cognitive function after the fecal flora from tumor-bearing and WT mice were transplanted into AD mice by gavage. The effect of flora transplantation on AD was analyzed by thioflavin T staining, western blot, and 16S RNA sequencing.

RESULTS

AD mice with FMT significantly improved short-term memory level and cognitive ability compared with Tg + NaCl group. Inflammatory factors in the plasma were regulated, and Aβ plaques burden in the hippocampus and cortex were decreased. FMT in the tumor-bearing group showed a higher significant amelioration in symptoms compared to the healthy group. 16S RNA sequencing revealed that FMT treatments could reverse the increased Firmicutes and Prevotella and the decreased Bacteroidetes, Bacteroides, and Sutterella in AD mice. AD mice transplanted with tumor-bearing mice feces additionally increased the density of Oscillospira, Odoribacter, and AF12. Furthermore, the predicted functional analyses showed that the metabolism of inorganic and organic salts in the intestinal flora of AD mice was also reversed by FMT.

CONCLUSION

Intestinal flora transplantation from tumor-bearing mice can ameliorate the cognitive impairment of AD mice.

Tumor necrosis factor-α-induced protein 8-like 2 Fosters Tumor-Associated Microbiota to Promote the Development of Colorectal Cancer

Although increasing evidence links the gut microbiota with the development of colorectal cancer, the molecular mechanisms for microbiota regulation of tumorigenesis are not fully understood. Here, we found that a member of the TNF-α-induced protein 8 (TNFAIP8) family called TIPE2 (TNFAIP8-like 2) was significantly upregulated in murine intestinal tumors and in human colorectal cancer (CRC), and colorectal cancer with high expression of Tipe2 mRNA associated with reduced survival time of patients. Consistent with these findings, TIPE2 deficiency significantly inhibited the development of CRC in mice treated with azoxymethane/dextran sodium sulfate and in Apcmin/+ mice. TIPE2 deficiency attenuated the severity of colitis by successfully resolving and restricting colonic inflammation and protected colonic myeloid cells from death during colitis. Transplantation of TIPE2-deficient bone marrow into WT mice successfully dampened the latter's tumorigenic phenotype, indicating a hematopoietic-specific role for TIPE2. Mechanistically, restricting the expansion of Enterobacteriaceae/E. coli decreased intestinal inflammation and reduced the incidence of colonic tumors. Collectively, these data suggest that hematopoietic TIPE2 regulates intestinal anti-tumor immunity by regulation of gut microbiota. TIPE2 may represent a new therapeutic target for treating CRC.

Biliary Diseases from the Microbiome Perspective: How Microorganisms Could Change the Approach to Benign and Malignant Diseases

Recent evidence regarding microbiota is modifying the cornerstones on pathogenesis and the approaches to several gastrointestinal diseases, including biliary diseases. The burden of biliary diseases, indeed, is progressively increasing, considering that gallstone disease affects up to 20% of the European population. At the same time, neoplasms of the biliary system have an increasing incidence and poor prognosis. Framing the specific state of biliary eubiosis or dysbiosis is made difficult by the use of heterogeneous techniques and the sometimes unwarranted invasive sampling in healthy subjects. The influence of the microbial balance on the health status of the biliary tract could also account for some of the complications surrounding the post-liver-transplant phase. The aim of this extensive narrative review is to summarize the current evidence on this topic, to highlight gaps in the available evidence in order to guide further clinical research in these settings, and, eventually, to provide new tools to treat biliary lithiasis, biliopancreatic cancers, and even cholestatic disease.

Deciphering the influence of urinary microbiota on FoxP3+ regulatory T cell infiltration and prognosis in Chinese patients with non-muscle-invasive bladder cancer

Despite increasing evidence that dysbiosis of urinary microbiota is closely correlated with bladder cancer, the influence of the urinary microbiota on immune evasion and tumor growth in bladder cancer is unknown. This study investigated whether the urinary microbiota influences intratumoral infiltration of FoxP3+ regulatory T cells, expression of Ki-67 and clinical prognosis in non-muscle-invasive bladder cancer. Forty male patients, including 12 and 28 with or without recurrence, respectively, were retrospectively enrolled. Midstream urine samples were preoperatively collected. Urinary microbiota composition was analyzed by 16s rDNA sequencing. Alpha and beta diversities were measured. LEfSe analysis was employed to identify specific bacteria associated with recurrence. Intratumoral infiltration of FoxP3+ regulatory T cells and Ki-67 expression were evaluated by immunohistochemistry. Patients with recurrence had higher α-diversity compared to those without (Shannon Index, P = 0.0007, Simpson Index, P = 0.0004). Distinct beta diversity was observed between recurrence and non-recurrence groups (weighted Unifrac P = 0.02; unweighted Unifrac P = 0.001). LEfSe analysis showed that the recurrence group displayed marked enrichment of Pseudomonas, Staphylococcus, Corynebacterium, and Acinetobacter genera. Patients with higher alpha diversity had elevated Ki-67 expression than those with lower alpha diversity (P = 0.0194), although microbial diversity was unassociated with infiltration of FoxP3+ regulatory T cells (P = 0.1653). Patients with lower urinary microbial diversity had prolonged recurrence-free survival compared to those with higher diversity. Perturbation of urinary microbiota may induce immune evasion and tumor growth, eventually contributing to unfavorable outcomes. Additional study is warranted to confirm a causal role of urinary microbiota in modulating antitumor immune response and survival in bladder cancer.

Microbiota-specific T follicular helper cells drive tertiary lymphoid structures and anti-tumor immunity against colorectal cancer

The composition of the intestinal microbiota is associated with both the development of tumors and the efficacy of anti-tumor immunity. Here, we examined the impact of microbiota-specific T cells in anti-colorectal cancer (CRC) immunity. Introduction of Helicobacter hepaticus (Hhep) in a mouse model of CRC did not alter the microbial landscape but increased tumor infiltration by cytotoxic lymphocytes and inhibited tumor growth. Anti-tumor immunity was independent of CD8⁺ T cells but dependent upon CD4⁺ T cells, B cells, and natural killer (NK) cells. Hhep colonization induced Hhep-specific T follicular helper (Tfh) cells, increased the number of colon Tfh cells, and supported the maturation of Hhep+ tumor-adjacent tertiary lymphoid structures. Tfh cells were necessary for Hhep-mediated tumor control and immune infiltration, and adoptive transfer of Hhep-specific CD4⁺ T cells to Tfh cell-deficient Bcl6^fl/flCd4^Cre mice restored anti-tumor immunity. Thus, introduction of immunogenic intestinal bacteria can promote Tfh-associated anti-tumor immunity in the colon, suggesting therapeutic approaches for the treatment of CRC.

COVID-19 and gut immunomodulation

The disease coronavirus disease 2019 (COVID-19) is a severe respiratory illness that has emerged as a devastating health problem worldwide. The disease outcome is heterogeneous, and severity is likely dependent on the immunity of infected individuals and comorbidities. Although symptoms of the disease are primarily associated with respiratory problems, additional infection or failure of other vital organs are being reported. Emerging reports suggest a quite common co-existence of gastrointestinal (GI) tract symptoms in addition to respiratory symptoms in many COVID-19 patients, and some patients show just the GI symptoms. The possible cause of the GI symptoms could be due to direct infection of the epithelial cells of the gut, which is supported by the fact that (1) The intestinal epithelium expresses a high level of angiotensin-converting enzyme-2 and transmembrane protease serine 2 protein that are required for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the cells; (2) About half of the severe COVID-19 patients show viral RNA in their feces and various parts of the GI tract; and (3) SARS-CoV-2 can directly infect gut epithelial cells in vitro (gut epithelial cells and organoids) and in vivo (rhesus monkey). The GI tract seems to be a site of active innate and adaptive immune responses to SARS-CoV-2 as clinically, stool samples of COVID-19 patients possess proinflammatory cytokines (interleukin 8), calprotectin (neutrophils activity), and immunoglobulin A antibodies. In addition to direct immune activation by the virus, impairment of GI epithelium integrity can evoke immune response under the influence of systemic cytokines, hypoxia, and changes in gut microbiota (dysbiosis) due to infection of the respiratory system, which is confirmed by the observation that not all of the GI symptomatic patients are viral RNA positive. This review comprehensively summarizes the possible GI immunomodulation by SARS-CoV-2 that could lead to GI symptoms, their association with disease severity, and potential therapeutic interventions.

Composition of intestinal flora affects the risk relationship between Alzheimer's disease/Parkinson's disease and cancer

An increasing number of epidemiological studies have shown that there is a significant inverse relationship between the onset of Alzheimer's disease/Parkinson's disease (AD/PD) and cancer, but the mechanism is still unclear. Considering that intestinal flora can connect them, we tried to explain this phenomenon from the intestinal flora. This review briefly introduced the relationship among AD/PD, cancer, and intestinal flora, studied metabolites or components of the intestinal flora and the role of intestinal barriers and intestinal hormones in AD/PD and cancer. After screening, a part of the flora capable of participating in the occurrence processes of the three diseases at the same time was obtained, the abundance changes of the special flora in AD/PD and various types of cancers were summarized, and they were classified according to the flora function and abundance, which in turn innovatively and reasonably explained the fact that AD/PD and cancer showed certain antagonism in epidemiological statistics from the perspective of intestinal flora. This review also proposed that viewing the risk relationship between diseases from the perspective of intestinal flora may provide new research ideas for the treatment of fecal microbiota transplantation (FMT) and related diseases.

Heterologous Prime-Boost Vaccination with a Peptide-Based Vaccine and Viral Vector Reshapes Dendritic Cell, CD4+ and CD8+ T Cell Phenotypes to Improve the Antitumor Therapeutic Effect

Simple Summary

Developing new therapeutic cancer vaccines is of paramount importance to counteract tumor escape observed after conventional therapies in certain types of cancer. We have previously shown that the combination of two different vaccine platforms, targeting tumor-specific antigens, resulted in potent immune responses in preclinical models. Here, we show that the heterologous prime-boost combination with a protein vaccine and a viral vector vesicular stomatitis virus immunologically reshapes the immune-excluded TC-1 tumor model as well as the inflamed MC-38 tumor model, leading to beneficial therapeutic efficacy. Furthermore, the treatment with a multi-epitope vaccine allowed us to appreciate the various repartition among three antigen-specific cytotoxic T-cell responses combined with the viral boost. The combination leads to improved efficacy in all animals and highlights the importance of combining tumor epitopes. Our vaccine strategy could be further extended to prophylactic cancer vaccines and beyond, for infectious diseases.

Abstract

Heterologous prime-boost settings with a protein vaccine and the viral vector vesicular stomatitis virus, both expressing tumor-associated antigens (KISIMA-TAA and VSV-GP-TAA), have been previously shown to generate potent antitumor immunity. In the cold TC-1 model (HPV antigen) and the immune-infiltrate MC-38 model (Adpgk, Reps1 and Rpl18 neo-antigens), we further investigated pivotal immune cells that educate CD8+ T cells. Heterologous prime-boost vaccination induced a superior antitumor response characterized by the increase in number and functionality of antigen-specific CD8+ T cells, recruitment of cross-presenting dendritic cells, and polarization of CD4+ T cells towards an antitumor Th1 phenotype within the tumor and tumor-draining lymph nodes, turning the cold TC-1 tumor into a hot, inflamed tumor. In the inflamed MC-38 tumor model, treatment combination markedly prolonged the overall survival of mice. Treatment with multi-epitope vaccines also induced high frequencies of multiple antigen specificities in the periphery and in the tumor. Prime-boost treatment reduced tumor-infiltrating regulatory CD4+ T cells whilst increasing cross-presenting dendritic cells in tumor-draining lymph nodes. In conclusion, heterologous prime-boost vaccination possesses the ability to induce a potent anti-tumor response in both immune-excluded and immune-infiltrated mouse tumor models. Additionally, this study highlights the design of a multi-epitope vaccine for cancer immunotherapy.

The Role of the Immune System in IBD-Associated Colorectal Cancer: From Pro to Anti-Tumorigenic Mechanisms

Patients with inflammatory bowel disease (IBD) have increased incidence of colorectal cancer (CRC). IBD-associated cancer follows a well-characterized sequence of intestinal epithelial changes, in which genetic mutations and molecular aberrations play a key role. IBD-associated cancer develops against a background of chronic inflammation and pro-inflammatory immune cells, and their products contribute to cancer development and progression. In recent years, the effect of the immunosuppressive microenvironment in cancer development and progression has gained more attention, mainly because of the unprecedented anti-tumor effects of immune checkpoint inhibitors in selected groups of patients. Even though IBD-associated cancer develops in the background of chronic inflammation which is associated with activation of endogenous anti-inflammatory or suppressive mechanisms, the potential role of an immunosuppressive microenvironment in these cancers is largely unknown. In this review, we outline the role of the immune system in promoting cancer development in chronic inflammatory diseases such as IBD, with a specific focus on the anti-inflammatory mechanisms and suppressive immune cells that may play a role in IBD-associated tumorigenesis.

Identification of a novel cancer microbiome signature for predicting prognosis of human breast cancer patients

BACKGROUND

Prognosis of breast cancer (BC) patients differs considerably and identifying reliable prognostic biomarker(s) is imperative. With evidence that the microbiome plays a critical role in the response to cancer therapies, we aimed to identify a cancer microbiome signature for predicting the prognosis of BC patients.

METHODS

The TCGA BC microbiome data (TCGA-BRCA-microbiome) was downloaded from cBioPortal. Univariate and multivariate Cox regression analyses were used to examine association of microbial abundance with overall survival (OS) and to identify a microbial signature for creating a prognostic scoring model. The performance of the scoring model was assessed by the area under the ROC curve (AUC). Nomograms using the microbial signature, clinical factors, and molecular subtypes were established to predict OS and progression-free survival (PFS).

RESULTS

Among 1406 genera, the abundances of 94 genera were significantly associated with BC patient OS in TCGA-BRCA-microbiome dataset. From that set we identified a 15-microbe prognostic signature and developed a 15-microbial abundance prognostic scoring (MAPS) model. Patients in low-risk group significantly prolong OS and PFS as compared to those in high-risk group. The time-dependent ROC curves with MAPS showed good predictive efficacy both in OS and PFS. Moreover, MAPS is an independent prognostic factor for OS and PFS over clinical factors and PAM50-based molecular subtypes and superior to the previously published 12-gene signature. The integration of MAPS into nomograms significantly improved prognosis prediction.

CONCLUSION

MAPS was successfully established to have independent prognostic value, and our study provides a new avenue for developing prognostic biomarkers by microbiome profiling.

Bacterial Extracellular Vesicles in Gastrointestinal Tract Cancer: An Unexplored Territory

Bacterial extracellular vesicles are membrane-enclosed, lipid bi-layer nanostructures that carry different classes of biomolecules, such as nucleic acids, lipids, proteins, and diverse types of small molecular metabolites, as their cargo. Almost all of the bacteria in the gut secrete extracellular vesicles to assist them in competition, survival, material exchange, host immune modulation, infection, and invasion. The role of gut microbiota in the development, progression, and pathogenesis of gastrointestinal tract (GIT) cancer has been well documented. However, the possible involvement of bacterial extracellular vesicles (bEVs) in GIT cancer pathophysiology has not been given due attention. Studies have illustrated the ability of bEVs to cross physiological barriers, selectively accumulate near tumor cells, and possibly alter the tumor microenvironment (TME). A systematic search of original published works related to bacterial extracellular vesicles on gastrointestinal cancer was performed for this review. The current systemic review outlines the possible impact of gut microbiota derived bEVs in GIT cancer in light of present-day understanding. The necessity of using advanced sequencing technologies, such as genetic, proteomic, and metabolomic investigation methodologies, to facilitate an understanding of the interrelationship between cancer-associated bacterial vesicles and gastrointestinal cancer is also emphasized. We further discuss the clinical and pharmaceutical potential of bEVs, along with future efforts needed to understand the mechanism of interaction of bEVs in GIT cancer pathogenesis.

Cytotoxic T-Cell Trafficking Chemokine Profiles Correlate With Defined Mucosal Microbial Communities in Colorectal Cancer

The involvement of gut microbiota in T-cell trafficking into tumor tissue of colorectal cancer (CRC) remains to be further elucidated. The current study aimed to evaluate the expression of major cytotoxic T-cell trafficking chemokines (CTTCs) and chemokine-associated microbiota profiles in both tumor and adjacent normal tissues during CRC progression. We analyzed the expression of chemokine C-X-C motif ligands 9, 10, and 11 (CXCL9, CXCL10, and CXCL11), and C-C motif ligand 5 (CCL5), characterized gut mucosa-associated microbiota (MAM), and investigated their correlations in CRC patients. Our results showed that the expression of CXCL9, CXCL10, and CXCL11 was significantly higher in tumor than in adjacent normal tissues in 136 CRC patients. Notably, the high expression of CXCL9 in tumor tissues was associated with enhanced CD8⁺ T-cell infiltration and improved survival. Moreover, the MAM in tumor tissues showed reduction of microbial diversity and increase of oral bacteria. Microbial network analysis identified differences in microbial composition and structure between tumor and adjacent normal tissues. In addition, stronger associations between oral bacteria and other gut microbes were observed. Furthermore, the correlation analysis between the defined MAM and individual CTTCs showed that the CTTCs' correlated operational taxonomic units (OTUs) in tumor and adjacent normal tissues rarely overlap with each other. Notably, all the enriched OTUs were positively correlated with the CTTCs in either tumor or adjacent normal tissues. Our findings demonstrated stronger interactions between oral bacteria and gut microbes, and a shifted correlation pattern between MAM and major CTTCs in tumor tissues, underlining possible mechanisms of gut microbiota-host interaction in CRC.

The Role of Gut Microbiota in Tumor Immunotherapy

Tumor immunotherapy is the fourth therapy after surgery, chemotherapy, and radiotherapy. It has made great breakthroughs in the treatment of some epithelial tumors and hematological tumors. However, its adverse reactions are common or even more serious, and the response rate in some solid tumors is not satisfactory. With the maturity of genomics and metabolomics technologies, the effect of intestinal microbiota in tumor development and treatment has gradually been recognized. The microbiota may affect tumor immunity by regulating the host immune system and tumor microenvironment. Some bacteria help fight tumors by activating immunity, while some bacteria mediate immunosuppression to help cancer cells escape from the immune system. More and more studies have revealed that the effects and complications of tumor immunotherapy are related to the composition of the gut microbiota. The composition of the intestinal microbiota that is sensitive to treatment or prone to adverse reactions has certain characteristics. These characteristics may be used as biomarkers to predict the prognosis of immunotherapy and may also be developed as “immune potentiators” to assist immunotherapy. Some clinical and preclinical studies have proved that microbial intervention, including microbial transplantation, can improve the sensitivity of immunotherapy or reduce adverse reactions to a certain extent. With the development of gene editing technology and nanotechnology, the design and development of engineered bacteria that contribute to immunotherapy has become a new research hotspot. Based on the relationship between the intestinal microbiota and immunotherapy, the correct mining of microbial information and the development of reasonable and feasible microbial intervention methods are expected to optimize tumor immunotherapy to a large extent and bring new breakthroughs in tumor treatment.

The role of microbiome in pancreatic cancer

Recent studies of the human microbiome have offered new insights into how the microbiome can impact cancer development and treatment. Specifically, in pancreatic ductal adenocarcinoma (PDAC), the microbiota has been shown to modulate PDAC risk, contribute to tumorigenesis, impact the tumor microenvironment, and alter treatment response. These findings provide rationale for further investigations into leveraging the microbiome to develop new strategies to diagnose and treat PDAC patients. There is growing evidence that microbiome analyses have the potential to become easily performed, non-invasive diagnostic, prognostic, and predictive biomarkers in pancreatic cancer. More excitingly, there is now emerging interest in developing interventions based on the modulation of microbiota. Fecal microbiota transplantation, probiotics, dietary changes, and antibiotics are all potential strategies to augment the efficacy of current therapeutics and reduce toxicities. While there are still challenges to overcome, this is a rapidly growing field that holds promise for translation into clinical practice and provides a new approach to improving patient outcomes.

Increased CD3+, CD8+, or FoxP3+ T Lymphocyte Infiltrations Are Associated with the Pathogenesis of Colorectal Cancer but Not with the Overall Survival of Patients

Tumor-infiltrating lymphocytes include heterogeneous populations of T lymphocytes that play crucial roles in the tumor immune response; importantly, their presence in the tumor tissue may predict clinical outcomes. Therefore, we herein studied the prognostic significance of the presence and location of CD3⁺, CD8⁺, and FoxP3⁺ T lymphocytes in colorectal cancer samples. In the intratumor analysis, our data did not reveal any association between lymphocyte infiltrations with clinical or pathological data. However, in the tumor margins, we found that the presence of high infiltrations of CD3⁺, CD8⁺, or FoxP3⁺ T lymphocytes were associated with TNM stages I-II (p = 0.021, p = 0.022, and p = 0.012, respectively) and absence of lymph node metastases (p = 0.010, p = 0.003, and p = 0.004, respectively). Despite these associations with good prognostic indicators, we were not able to find any statistically significant alterations in the overall survival of the patients, even though high infiltrations of FoxP3⁺ T lymphocytes in the tumor margins resulted in an increased overall survival of 14 months. Taken together, these data show that the presence of CD3⁺, CD8⁺, or FoxP3⁺T lymphocyte infiltrates in the tumor margins are associated with the pathogenesis of CRC, but only high Foxp3⁺ T lymphocyte infiltrations in the tumor invasive margins are inclined to indicate favorable prognosis.

Ultrafine Jujube Powder Enhances the Infiltration of Immune Cells during Anti-PD-L1 Treatment against Murine Colon Adenocarcinoma

Simple Summary

While modulating gut microbiota using dietary intervention with natural nutrients has proven to be effective in improving the response rate of immune checkpoint inhibitors (ICIs), the underpinning mechanism is poorly understood. This work demonstrates that the oral administration of ultrafine jujube powder (JP) let to a significant alteration of gut microbiota, an increased abundance of Clostridiales, including Ruminococcaceae and Lachnospiraceae, an elevated SCFA production, an intensified infiltration of CD8⁺ T cells to the tumor microenvironment, and a greatly improved response of anti-PD-L1 treatment against murine colon adenocarcinoma. Moreover, the size of the JP particles had a significant impact on the abovementioned attributes. The present study demonstrates that dietary intervention with nutrients is highly effective in modulating the gut microbiota for an improved immune checkpoint blockage therapy.

Abstract

Whereas dietary intervention with natural nutrients plays an important role in activating the immune response and holds unprecedented application potential, the underpinning mechanism is poorly understood. The present work was dedicated to comprehensively examine the effects of ultrafine jujube powder (JP) on the gut microbiota and, consequentially, the effects associated with the response rate to anti-PD-L1 treatment against murine colon adenocarcinoma. A murine colon adenocarcinoma model with anti-PD-L1 immunotherapy was established to evaluate how dietary interventions affect the microbiota. In vitro and in vivo experiments confirmed the role of SCFAs in the immune response. Oral administration of JP greatly improves the response of anti-PD-L1 treatment against murine colon adenocarcinoma. Such an improvement is associated with the alteration of gut microbiota which leads to an increased abundance of Clostridiales, including Ruminococcaceae and Lachnospiraceae, an elevated SCFA production, and an intensified infiltration of CD8⁺ T cells to the tumor microenvironment. This work demonstrates that JP is particularly effective in modulating the gut microbiota for an improved immune checkpoint blockage therapy by boosting cytotoxic CD8⁺ T cells in tumor-infiltrating lymphocytes. The experimental findings of the present study are helpful for the development of dietary intervention methods for cancer immunotherapy using natural nutrients.

TPL Inhibits the Invasion and Migration of Drug-Resistant Ovarian Cancer by Targeting the PI3K/AKT/NF-κB-Signaling Pathway to Inhibit the Polarization of M2 TAMs

Chemoresistance is the primary reason for the poor prognosis of patients with ovarian cancer, and the search for a novel drug treatment or adjuvant chemotherapy drug is an urgent need. The tumor microenvironment plays key role in the incidence and development of tumors. As one of the most important components of the tumor microenvironment, M2 tumor-associated macrophages are closely related to tumor migration, invasion, immunosuppressive phenotype and drug resistance. Many studies have confirmed that triptolide (TPL), one of the principal components of Tripterygium wilfordii, possesses broad-spectrum anti-tumor activity. The aims of this study were to determine whether TPL could inhibit the migration and invasion of A2780/DDP cells in vitro and in vivo by inhibiting the polarization of M2 tumor-associated macrophages (TAMs); to explore the mechanism(s) underlying TPL effects; and to investigate the influence of TPL on murine intestinal symbiotic microbiota. In vitro results showed that M2 macrophage supernatant slightly promoted the proliferation, invasion, and migration of A2780/DDP cells, which was reversed by TPL in a dose-dependent manner. Animal experiments showed that TPL, particularly TPL + cisplatin (DDP), significantly reduced the tumor burden, prolonged the life span of mice by inhibiting M2 macrophage polarization, and downregulated the levels of CD31 and CD206 (CD31 is the vascular marker and CD206 is the macrophage marker), the mechanism of which may be related to the inhibition of the PI3K/Akt/NF-κB signaling pathway. High-throughput sequencing results of the intestinal microbiota in nude mice illustrated that Akkermansia and Clostridium were upregulated by DDP and TPL respective. We also found that Lactobacillus and Akkermansia were downregulated by DDP combined with TPL. Our results highlight the importance of M2 TAMs in Epithelial Ovarian Cancer (EOC) migration ability, invasiveness, and resistance to DDP. We also preliminarily explored the mechanism governing the reversal of the polarization of M2 macrophages by TPL.

A Comprehensive Overview of Colon Cancer- A Grim Reaper of the 21st Century

A few decades ago, the incidence of colorectal cancer (CRC) was low and is now the fourth in the list of deadly cancers producing nearly a million deaths annually. A population that is aging along with risk factors such as smoking, obesity, sedentary lifestyle with little or no physical activity, and non-healthy food habits of developed countries can increase the risk of colorectal cancer. The balance in gut microbiota and the metabolites produced during bacterial fermentation within the host plays a significant role in regulating intestinal diseases as well as colorectal cancer development. Recent progress in the understanding of illness resulted in multiple treatment options such as surgery, radiation, and chemotherapy, including targeted therapy and multitherapies. The treatment plan for CRC depends on the location, stage and grade of cancer as well as genomic biomarker tests. Despite all the advancements made in the genetic and molecular aspects of the disease, the knowledge seems inadequate as the drug action as well as the wide variation in drug response did not appear strongly correlated with the individual molecular and genetic characteristics, which suggests the requirement of comprehensive molecular understanding of this complex heterogeneous disease. Furthermore, multitherapies or a broad spectrum approach, which is an amalgamation of the various promising as well as effective therapeutic strategies that can tackle heterogeneity and act on several targets of the disease, need to be validated in clinical studies. The latest treatment options have significantly increased the survival of up to three years in the case of advanced disease. The fact that colorectal cancer is developed from a polypoid precursor, as well as the symptoms of the disease that occur at an advanced stage, underlines how screening programs can help early detection and decrease mortality as well as morbidity from CRC.

Reinforcing the Immunocompromised Host Defense against Fungi: Progress beyond the Current State of the Art

Despite the availability of a variety of antifungal drugs, opportunistic fungal infections still remain life-threatening for immunocompromised patients, such as those undergoing allogeneic hematopoietic cell transplantation or solid organ transplantation. Suboptimal efficacy, toxicity, development of resistant variants and recurrent episodes are limitations associated with current antifungal drug therapy. Adjunctive immunotherapies reinforcing the host defense against fungi and aiding in clearance of opportunistic pathogens are continuously gaining ground in this battle. Here, we review alternative approaches for the management of fungal infections going beyond the state of the art and placing an emphasis on fungus-specific T cell immunotherapy. Harnessing the power of T cells in the form of adoptive immunotherapy represents the strenuous protagonist of the current immunotherapeutic approaches towards combating invasive fungal infections. The progress that has been made over the last years in this field and remaining challenges as well, will be discussed.

The Role of Gut Microbiota in Modulating Tumor Growth and Anticancer Agent Efficacy

An increasing number of studies have revealed an interaction between gut microbiota and tumors. The enrichment of specific bacteria strains in the intestines has been found to modulate tumor growth and influence the mechanisms of tumor treatment. Various bacteria are involved in modulating the effects of chemotherapeutic drugs currently used to treat patients with cancer, and they affect not only gastrointestinal tract tumors but also distant organ tumors. In addition, changes in the gut microbiota are known to be involved in the antitumor immune response as well as the modulation of the intestinal immune system. As a result, the gut microbiota plays an important role in modulating the efficacy of immune checkpoint inhibitors. Therefore, gut microbiota could be considered as an adjuvant treatment option with other cancer treatment or as another marker for predicting treatment response. In this review, we examine how gut microbiota affects cancer treatments.

Integrating Viral Metagenomics into an Ecological Framework

Viral metagenomics has expanded our knowledge of the ecology of uncultured viruses, within both environmental (e.g., terrestrial and aquatic) and host-associated (e.g., plants and animals, including humans) contexts. Here, we emphasize the implementation of an ecological framework in viral metagenomic studies to address questions in virology rarely considered ecological, which can change our perception of viruses and how they interact with their surroundings. An ecological framework explicitly considers diverse variants of viruses in populations that make up communities of interacting viruses, with ecosystem-level effects. It provides a structure for the study of the diversity, distributions, dynamics, and interactions of viruses with one another, hosts, and the ecosystem, including interactions with abiotic factors. An ecological framework in viral metagenomics stands poised to broadly expand our knowledge in basic and applied virology. We highlight specific fundamental research needs to capitalize on its potential and advance the field. Expected final online publication date for the Annual Review of Virology, Volume 8 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Individuals at risk for rheumatoid arthritis harbor differential intestinal bacteriophage communities with distinct metabolic potential

Rheumatoid arthritis (RA) is an autoimmune disease characterized in seropositive individuals by the presence of anti-cyclic citrullinated protein (CCP) antibodies. RA is linked to the intestinal microbiota, yet the association of microbes with CCP serology and their contribution to RA is unclear. We describe intestinal phage communities of individuals at risk for developing RA, with or without anti-CCP antibodies, whose first-degree relatives have been diagnosed with RA. We show that at-risk individuals harbor intestinal phage compositions that diverge based on CCP serology, are dominated by Streptococcaceae, Bacteroidaceae, and Lachnospiraceae phages, and may originate from disparate ecosystems. These phages encode unique repertoires of auxiliary metabolic genes, which associate with anti-CCP status, suggesting that these phages directly influence the metabolic and immunomodulatory capability of the microbiota. This work sets the stage for the use of phages as preclinical biomarkers and provides insight into a possible microbial-based causation of RA disease development.

Mechanisms of PD-L1 Regulation in Malignant and Virus-Infected Cells

Programmed cell death protein 1 (PD-1), a receptor on T cells, and its ligand, PD-L1, have been a topic of much interest in cancer research. Both tumour and virus-infected cells can upregulate PD-L1 to suppress cytotoxic T-cell killing. Research on the PD-1/PD-L1 axis has led to the development of anti-PD-1/PD-L1 immune checkpoint blockades (ICBs) as promising cancer therapies. Although effective in some cancer patients, for many, this form of treatment is ineffective due to a lack of immunogenicity in the tumour microenvironment (TME). Despite the development of therapies targeting the PD-1/PD-L1 axis, the mechanisms and pathways through which these proteins are regulated are not completely understood. In this review, we discuss the latest research on molecules of inflammation and innate immunity that regulate PD-L1 expression, how its expression is regulated during viral infection, and how it is modulated by different cancer therapies. We also highlight existing research on the development of different combination therapies with anti-PD-1/PD-L1 antibodies. This information can be used to develop better cancer immunotherapies that take into consideration the pathways involved in the PD-1/PD-L1 axis, so these molecules do not reduce their efficacy, which is currently seen with some cancer therapies. This review will also assist in understanding how the TME changes during treatment, which will provide further rationale for combination therapies.

Intratumour microbiome associated with the infiltration of cytotoxic CD8+ T cells and patient survival in cutaneous melanoma

OBJECTIVE

The gut microbiome plays an important role in systemic inflammation and immune response. Microbes can translocate and reside in tumour niches. However, it is unclear how the intratumour microbiome affects immunity in human cancer. The purpose of this study was to investigate the association between intratumour bacteria, infiltrating CD8+ T cells and patient survival in cutaneous melanoma.

METHODS

Using The Cancer Genome Altas's cutaneous melanoma RNA sequencing data, levels of intratumour bacteria and infiltrating CD8+ T cells were determined. Correlation between intratumour bacteria and infiltrating CD8+ T cells or chemokine gene expression and survival analysis of infiltrating CD8+ T cells and Lachnoclostridium in cutaneous melanoma were performed.

RESULTS

Patients with low levels of CD8+ T cells have significantly shorter survival than those with high levels. The adjusted hazard ratio was 1.57 (low vs high) (95% confidence interval: 1.17-2.10, p = 0.002). Intratumour bacteria of the Lachnoclostridium genus ranked top in a positive association with infiltrating CD8+ T cells (correlation coefficient = 0.38, p = 9.4 × 10^-14), followed by Gelidibacter (0.31, p = 1.13 × 10^-9), Flammeovirga (0.29, p = 1.96 × 10^-8) and Acinetobacter (0.28, p = 8.94 × 10^-8). These intratumour genera positively correlated with chemokine CXCL9, CXCL10 and CCL5 expression. The high Lachnoclostridium load significantly reduced the mortality risk (p = 0.0003). However, no statistically significant correlation was observed between intratumour Lachnoclostridium abundance and the levels of either NK, B or CD4+ T cells.

CONCLUSION

Intratumour-residing gut microbiota could modulate chemokine levels and affect CD8+ T-cell infiltration, consequently influencing patient survival in cutaneous melanoma. Manipulating the intratumour gut microbiome may benefit patient outcomes for those undergoing immunotherapy.

CD8+ T Cells in GCA and GPA: Bystanders or Active Contributors?

Vasculitis refers to inflammation of blood vessels and can cause a variety of serious complications depending on which vessels are affected. Two different forms of vasculitis are Giant Cell Arteritis (GCA) and Granulomatosis with Polyangiitis (GPA). GCA is the most common form of vasculitis in adults affecting the large arteries and can lead to visual impairment and development of aneurysms. GPA affects small- and medium-sized blood vessels predominantly in the lungs and kidneys resulting in organ failure. Both diseases can potentially be fatal. Although the pathogenesis of GCA and GPA are incompletely understood, a prominent role for CD4+ T cells has been implicated in both diseases. More recently, the role of CD8+ T cells has gained renewed interest. CD8+ T cells are important players in the adaptive immune response against intracellular microorganisms. After a general introduction on the different forms of vasculitis and their association with infections and CD8+ T cells, we review the current knowledge on CD8+ T-cell involvement in the immunopathogenesis of GCA and GPA focusing on phenotypic and functional features of circulating and lesional CD8+ T cells. Furthermore, we discuss to which extent aging is associated with CD8+ T-cell phenotype and function in GCA and GPA.

Gut microbiota, NLR proteins, and intestinal homeostasis

The gastrointestinal tract harbors a highly complex microbial community, which is referred to as gut microbiota. With increasing evidence suggesting that the imbalance of gut microbiota plays a significant role in the pathogenesis of multiple diseases, interactions between the host immune system and the gut microbiota are now attracting emerging interest. Nucleotide-binding and leucine-rich repeat–containing receptors (NLRs) encompass a large number of innate immune sensors and receptors, which mediate the activation of Caspase-1 and the subsequent release of mature interleukin-1β and interleukin-18. Several family members have been found to restrain rather than activate inflammatory cytokines and immune signaling. NLR family members are central regulators of pathogen recognition, host immunity, and inflammation with utmost importance in human diseases. In this review, we focus on the potential roles played by NLRs in controlling and shaping the microbiota community and discuss how the functional axes interconnecting gut microbiota with NLRs impact the modulation of colitis, inflammatory bowel diseases, and colorectal cancer.

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.

The tumor microenvironment shapes the molecular characteristics of exhausted CD8+ T cells

The persistent antigen stimulation during chronic infections and cancer results in CD8⁺ T cell exhaustion. The exhausted T (Tex) cells within the tumor microenvironment (TME) are characterized by increased expression of multiple co-inhibitory receptors simultaneously, progressive loss of effector function, poor proliferation and self-renewal capacity, and dysregulated metabolic activity. Emerging insights into molecular mechanisms underlying T cell exhaustion have proposed potential approaches to improve the efficacy of cancer immunotherapy via restoring the effector function of Tex cells. In this review, we summarize the fundamental characteristics (e.g., inhibitory receptors and transcriptional factors) regarding Tex cell differentiation and discuss in particular how those exhaustion features are acquired and shaped by key factors within the TME. Additionally, we discuss the progress and limitations of current cancer immunotherapeutic strategies targeting Tex cells in clinical setting.

New Insights Into the Cancer-Microbiome-Immune Axis: Decrypting a Decade of Discoveries

The past decade has witnessed groundbreaking advances in the field of microbiome research. An area where immense implications of the microbiome have been demonstrated is tumor biology. The microbiome affects tumor initiation and progression through direct effects on the tumor cells and indirectly through manipulation of the immune system. It can also determine response to cancer therapies and predict disease progression and survival. Modulation of the microbiome can be harnessed to potentiate the efficacy of immunotherapies and decrease their toxicity. In this review, we comprehensively dissect recent evidence regarding the interaction of the microbiome and anti-tumor immune machinery and outline the critical questions which need to be addressed as we further explore this dynamic colloquy.

Antibiotic-Related Changes in Microbiome: The Hidden Villain behind Colorectal Carcinoma Immunotherapy Failure

The interplay between drugs and microbiota is critical for successful treatment. An accumulating amount of evidence has identified the significant impact of intestinal microbiota composition on cancer treatment response, particularly immunotherapy. The possible molecular pathways of the interaction between immune checkpoint inhibitors (ICIs) and the microbiome can be used to reverse immunotherapy tolerance in cancer by using various kinds of interventions on the intestinal bacteria. This paper aimed to review the data available on how the antibiotic-related changes in human microbiota during colorectal cancer (CRC) treatment can affect and determine ICI treatment outcomes. We also covered the data that support the potential intimate mechanisms of both local and systemic immune responses induced by changes in the intestinal microbiota. However, further better-powered studies are needed to thoroughly assess the clinical significance of antibiotic-induced alteration of the gut microbiota and its impact on CRC treatment by direct observations of patients receiving antibiotic treatment.

Human gut microbial communities dictate efficacy of anti-PD-1 therapy in a humanized microbiome mouse model of glioma

Background

Although immunotherapy works well in glioblastoma (GBM) preclinical mouse models, the therapy has not demonstrated efficacy in humans. To address this anomaly, we developed a novel humanized microbiome (HuM) model to study the response to immunotherapy in a preclinical mouse model of GBM.

Methods

We used 5 healthy human donors for fecal transplantation of gnotobiotic mice. After the transplanted microbiomes stabilized, the mice were bred to generate 5 independent humanized mouse lines (HuM1-HuM5).

Results

Analysis of shotgun metagenomic sequencing data from fecal samples revealed a unique microbiome with significant differences in diversity and microbial composition among HuM1-HuM5 lines. All HuM mouse lines were susceptible to GBM transplantation, and exhibited similar median survival ranging from 19 to 26 days. Interestingly, we found that HuM lines responded differently to the immune checkpoint inhibitor anti-PD-1. Specifically, we demonstrate that HuM1, HuM4, and HuM5 mice are nonresponders to anti-PD-1, while HuM2 and HuM3 mice are responsive to anti-PD-1 and displayed significantly increased survival compared to isotype controls. Bray-Curtis cluster analysis of the 5 HuM gut microbial communities revealed that responders HuM2 and HuM3 were closely related, and detailed taxonomic comparison analysis revealed that Bacteroides cellulosilyticus was commonly found in HuM2 and HuM3 with high abundances.

Conclusions

The results of our study establish the utility of humanized microbiome mice as avatars to delineate features of the host interaction with gut microbial communities needed for effective immunotherapy against GBM.

NLRP3 Inflammasome at the Interface of Inflammation, Endothelial Dysfunction, and Type 2 Diabetes

Type 2 diabetes mellitus (T2DM), accounting for 90-95% cases of diabetes, is characterized by chronic inflammation. The mechanisms that control inflammation activation in T2DM are largely unexplored. Inflammasomes represent significant sensors mediating innate immune responses. The aim of this work is to present a review of links between the NLRP3 inflammasome, endothelial dysfunction, and T2DM. The NLRP3 inflammasome activates caspase-1, which leads to the maturation of pro-inflammatory cytokines interleukin 1β and interleukin 18. In this review, we characterize the structure and functions of NLRP3 inflammasome as well as the most important mechanisms and molecules engaged in its activation. We present evidence of the importance of the endothelial dysfunction as the first key step to activating the inflammasome, which suggests that suppressing the NLRP3 inflammasome could be a new approach in depletion hyperglycemic toxicity and in averting the onset of vascular complications in T2DM. We also demonstrate reports showing that the expression of a few microRNAs that are also known to be involved in either NLRP3 inflammasome activation or endothelial dysfunction is deregulated in T2DM. Collectively, this evidence suggests that T2DM is an inflammatory disease stimulated by pro-inflammatory cytokines. Finally, studies revealing the role of glucose concentration in the activation of NLRP3 inflammasome are analyzed. The more that is known about inflammasomes, the higher the chances to create new, effective therapies for patients suffering from inflammatory diseases. This may offer potential novel therapeutic perspectives in T2DM prevention and treatment.

Implications of the microbiome in the development and treatment of pancreatic cancer: Thinking outside of the box by looking inside the gut

Pancreatic ductal adenocarcinoma is the third leading cause of cancer-related death in the United States. As one of the most lethal cancer types, the prognosis for patients diagnosed with pancreatic cancer remains dismal and novel investigations are urgently needed. Evidence for an association of microbes with pancreatic cancer risk, development, treatment response, and post-treatment survivorship is rapidly developing. Herein, we provide an overview on the role of the microbiome as it relates to the natural history of pancreatic cancer, including host immune interactions, alterations in metabolism, direct carcinogenic effect, and its role in treatment response.

Gut Microbial Signatures in Sporadic and Hereditary Colorectal Cancer

Colorectal cancer (CRC) is the fourth most common cause of cancer-related death and the third most common cancer in the world. Depending on the origin of the mutation, colorectal carcinomas are classified as sporadic or hereditary. Cancers derived from mutations appearing during life, affecting individual cells and their descendants, are called sporadic and account for almost 95% of the CRCs. Less than 5% of CRC cases result from constitutional mutations conferring a very high risk of developing cancer. Screening for hereditary-related cancers is offered to individuals at risk for hereditary CRC, who have either not undergone genetic evaluation or have uncertain genetic test results. In this review, we briefly summarize the main findings on the correlation between sporadic CRC and the gut microbiota, and we specifically focus on the few evidences about the role that gut microorganisms have on the development of CRC hereditary syndromes. The characterization of a gut microbiota associated with an increased risk of developing CRC could have a profound impact for prevention purposes. We also discuss the potential role of the gut microbiota as therapeutic treatment.

Gut microbiota influence tumor development and Alter interactions with the human immune system

Recent scientific advances have greatly enhanced our understanding of the complex link between the gut microbiome and cancer. Gut dysbiosis is an imbalance between commensal and pathogenic bacteria and the production of microbial antigens and metabolites. The immune system and the gut microbiome interact to maintain homeostasis of the gut, and alterations in the microbiome composition lead to immune dysregulation, promoting chronic inflammation and development of tumors. Gut microorganisms and their toxic metabolites may migrate to other parts of the body via the circulatory system, causing an imbalance in the physiological status of the host and secretion of various neuroactive molecules through the gut-brain axis, gut-hepatic axis, and gut-lung axis to affect inflammation and tumorigenesis in specific organs. Thus, gut microbiota can be used as a tumor marker and may provide new insights into the pathogenesis of malignant tumors.

Targeting the aryl hydrocarbon receptor in stem cells to improve the use of food as medicine

Purpose of review

Intestinal stem cells, the most rapidly proliferating adult stem cells, are exquisitely sensitive to extrinsic dietary factors. Uncontrolled regulation of intestinal stem cells is closely linked to colon tumorigenesis. This review focuses on how dietary and microbial derived cues regulate intestinal stem cell functionality and colon tumorigenesis in mouse models by targeting the aryl hydrocarbon receptor (AhR).

Recent findings

AhR, a ligand activated transcription factor, can integrate environmental, dietary and microbial cues to modulate intestinal stem cell proliferation, differentiation and their microenvironment, affecting colon cancer risk. Modulation of AhR activity is associated with many chronic diseases, including inflammatory bowel diseases where AhR expression is protective.

Summary

AhR signaling controls the maintenance and differentiation of intestinal stem cells, influences local niche factors, and plays a protective role in colon tumorigenesis. Mounting evidence suggests that extrinsic nutritional/dietary cues which modulate AhR signaling may be a promising approach to colon cancer chemoprevention.

The gut microbiome: an under-recognised contributor to the COVID-19 pandemic?

The novel coronavirus infection (COVID-19) caused by the SARS-CoV-2 virus has spread rapidly across the globe, culminating in major global morbidity and mortality. As such, there has been a rapid escalation in scientific and clinical activity aimed at increasing our comprehension of this virus. This volume of work has led to early insights into risk factors associated with severity of disease, and mechanisms that underpin the virulence and dynamics involved in viral transmission. These insights ultimately may help guide potential therapeutics to reduce the human, economic and social impact of this pandemic. Importantly, the gastrointestinal (GI) tract has emerged as an important organ influencing propensity to, and potentially severity of, COVID-19 infection. Furthermore, the gut microbiome has been linked to a variety of risk factors for COVID-19 infection, and manipulation of the gut microbiome is an attractive potential therapeutic target for a number of diseases. While data profiling the gut microbiome in COVID-19 infection to date are limited, they support the possibility of several routes of interaction between COVID-19, the gut microbiome, angiotensin converting enzyme 2 (ACE-2) expression in the small bowel and colon and gut inflammation. This article will explore the evidence that implicates the gut microbiome as a contributing factor to the pathogenesis, severity and disease course of COVID-19, and speculate about the gut microbiome's capability as a therapeutic avenue against COVID-19.

LAY SUMMARY

It has been noted that certain baseline gut profiles of COVID-19 patients are associated with a more severe disease course, and the gut microbiome impacts the disease course of several contributory risk factors to the severity of COVID-19. A protein called ACE-2, which is found in the small intestine among other sites, is a key receptor for COVID-19 virus entry; there is evidence that the gut microbiome influences ACE-2 receptor expression, and hence may play a role in influencing COVID-19 infectivity and disease severity. Furthermore, the gut microbiome plays a significant role in immune regulation, and hence may be pivotal in influencing the immune response to COVID-19. In terms of understanding COVID-19 treatments, the gut microbiome is known to interact with several drug classes being used to target COVID-19 and should be factored into our understanding of how patients respond to treatment. Importantly, our understanding of the role of the gut microbiome in COVID-19 infection remains in its infancy, but future research may potentially aid our mechanistic understanding of viral infection, and new ways in which we might approach treating it.

Atypical immunometabolism and metabolic reprogramming in liver cancer: Deciphering the role of gut microbiome

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related mortality worldwide. Much recent research has delved into understanding the underlying molecular mechanisms of HCC pathogenesis, which has revealed to be heterogenous and complex. Two major hallmarks of HCC include: (i) a hijacked immunometabolism and (ii) a reprogramming in metabolic processes. We posit that the gut microbiota is a third component in an entanglement triangle contributing to HCC progression. Besides metagenomic studies highlighting the diagnostic potential in the gut microbiota profile, recent research is pinpointing the gut microbiota as an instigator, not just a mere bystander, in HCC. In this chapter, we discuss mechanistic insights on atypical immunometabolism and metabolic reprogramming in HCC, including the examination of tumor-associated macrophages and neutrophils, tumor-infiltrating lymphocytes (e.g., T-cell exhaustion, regulatory T-cells, natural killer T-cells), the Warburg effect, rewiring of the tricarboxylic acid cycle, and glutamine addiction. We further discuss the potential involvement of the gut microbiota in these characteristics of hepatocarcinogenesis. An immediate highlight is that microbiota metabolites (e.g., short chain fatty acids, secondary bile acids) can impair anti-tumor responses, which aggravates HCC. Lastly, we describe the rising 'new era' of immunotherapies (e.g., immune checkpoint inhibitors, adoptive T-cell transfer) and discuss for the potential incorporation of gut microbiota targeted therapeutics (e.g., probiotics, fecal microbiota transplantation) to alleviate HCC. Altogether, this chapter invigorates for continuous research to decipher the role of gut microbiome in HCC from its influence on immunometabolism and metabolic reprogramming.

Microbiome in cancer progression and therapy

A myriad of microbes living together with the host constitute microbiota, which possesses very diverse functions in regulation of host physiology. Recently, it has been unequivocally demonstrated that microbiota regulates cancer initiation, progression and responses to therapy. Here we review known pro-tumorigenic and anti-tumorigenic function of microbiota and mechanisms how microbes can regulate cancer cells and immune and stromal cells within the tumor microenvironment.

Effect of bacterial contamination in bile on pancreatic cancer cell survival

BACKGROUND

Introduction of gut flora into the biliary system is common owing to biliary stenting in patients with obstructing pancreatic head cancer. We hypothesize that alteration of biliary microbiome modifies bile content that modulates pancreatic cancer cell survival.

METHODS

Human bile samples were collected during pancreaticoduodenectomy. Bacterial strains were isolated from contaminated (stented) bile and identified using 16S ribosomal RNA sequencing. Human pancreatic cancer cells (AsPC1, CFPAC, Panc1) were treated for 24 hours with sterile (nonstented) bile, contaminated (stented) bile, and sterile bile preincubated with 10⁶ colony forming unit of live bacteria isolated from contaminated bile or a panel of bile acids for 24 hours at 37°C, and evaluated using CellTiter-Blue Cell Viability Assay (Promega Corp. Madison, WI). Human bile (30-50 μl/mouse) was coinjected intraperitoneally with 10⁵ Panc02 mouse pancreatic cancer cells in C57BL6/N mice to evaluate the impact of bile on peritoneal metastasis 3 to 4 weeks after tumor challenge.

RESULTS

While all bile samples significantly reduced peritoneal metastasis of Panc02 cells in mice, some contaminated bile samples had diminished antitumor effect. All sterile bile (n = 4) reduced pancreatic cancer cell survival in vitro. Only 40% (2/5) of contaminated bile samples had significant effect. Preincubation of sterile bile with live Enterococcus faecalis or Streptococcus oralis modified the antitumor effect of sterile bile. These changes were not observed with culture media preincubated with live bacteria, suggesting live gut bacteria can modify the antitumor components present in bile. Conjugated bile acids were more potent than unconjugated cholic acid in reducing pancreatic cancer cell survival.

CONCLUSION

Alteration of bile microbiome from biliary stenting has a direct impact on pancreatic cancer cell survival. Further study is warranted to determine if this microbiome shift alters tumor microenvironment.

Computational analysis of eugenol inhibitory activity in lipoxygenase and cyclooxygenase pathways

Chronic inflammation is triggered by numerous diseases such as osteoarthritis, Crohn's disease and cancer. The control of the pro-inflammatory process can prevent, mitigate and/or inhibit the evolution of these diseases. Therefore, anti-inflammatory drugs have been studied as possible compounds to act in these diseases. This paper proposes a computational analysis of eugenol in relation to aspirin and diclofenac and analyzing the ADMET profile and interactions with COX-2 and 5-LOX enzymes, important enzymes in the signaling pathway of pro-inflammatory processes. Through the analysis of ADMET in silico, it was found that the pharmacokinetic results of eugenol are similar to NSAIDs, such as diclofenac and aspirin. Bioinformatics analysis using coupling tests showed that eugenol can bind to COX-2 and 5-LOX. These results corroborate with different findings in the literature that demonstrate anti-inflammatory activity with less gastric irritation, bleeding and ulcerogenic side effects of eugenol. The results of bioinformatics reinforce studies that try to propose eugenol as an anti-inflammatory compound that can act in the COX-2/5-LOX pathways, replacing some NSAIDs in different diseases.