Sodium butyrate induces autophagy in colorectal cancer cells through LKB1/AMPK signaling

The butyrate derived from probiotic Clostridium butyricum exhibits an inhibitory effect on multiple myeloma through cell death induction

Multiple myeloma (MM) is a hematological malignancy characterized by a poor prognosis. While certain probiotics have been shown to produce antitumor molecules that inhibit solid tumor progression, it remains unclear whether probiotic-derived compounds can exert similar effects on hematological tumors, such as MM. In this study, we screened the cell-free culture supernatants (CFCS) of 24 probiotic strains for antitumor effects against multiple myeloma (MM) cells and identified that the CFCS from Clostridium butyricum (C. butyricum) demonstrated the most significant reduction in MM cell viability. Further fractionation of this CFCS through reverse-phase and gel filtration chromatography revealed a high enrichment of butyrate in the antitumor fraction, as confirmed by gas chromatography-mass spectrometry. Butyrate reduced MM cell viability in a concentration-dependent manner. Butyrate was significantly more cytotoxic to RPMI-8226 cells than peripheral blood mononuclear cells (PBMCs) isolated from two non-cancerous individuals. In the xenograft model of RPMI-8226 cells, butyrate showed significant inhibition of tumor formation. Cell cycle analysis showed that butyrate induced G1 phase arrest and increased sub-G1 phase, suggesting DNA fragmentation. Western blot analysis demonstrated that butyrate treatment led to cleaved poly ADP-ribose polymerase (PARP) accumulation. Additionally, flow cytometry showed an increase in annexin V positive MM cells, indicating apoptosis. Butyrate also exhibited synergistic antitumor activity when combined with bortezomib, a proteasome inhibitor. These findings suggest that probiotic-derived molecules, including butyrate, may enhance the therapeutic effect of hematological malignancy, such as MM.

Sodium butyrate and sodium propionate inhibit breast cancer cell migration and invasion through regulation of epithelial-to-mesenchymal transition and suppression of MEK/ERK signaling pathway

Objective

This study aims to investigate the roles played by NaB and NaP in breast carcinogenesis by elucidating their potential anti-metastatic effects in the context of tumor migration, invasion, and EMT regulation in two distinct breast cancer cell lines, MCF-7 and MDA-MB-231.

Methods

The cytotoxic effect of both compounds on 3D spheroid formation was evaluated using a hanging drop assay. The anti-migratory and anti-invasive potentials of NaB and NaP were investigated through transwell migration and invasion assays. Moreover, their role in regulating epithelial-to-mesenchymal transition (EMT) was examined by assessing E-cadherin, vimentin, and β-catenin mRNA and protein expression levels through RT-qPCR and Western blot or flow cytometry. β-Catenin localization upon treatment was further visualized via immunofluorescence. Protein expression of MEK, p-MEK, ERK, and p-ERK was analyzed by Western blot.

Results

Our results revealed a dose- and time-dependent impairment of spheroid formation in both cell lines, with NaB exerting a more potent effect than NaP. Both SCFAs were able to significantly inhibit migration and invasion of MDA-MB-231 cells following 24 h of treatment. Moreover, treatment with NaB or NaP altered the mRNA and protein profile of EMT-associated markers and abrogated the nuclear translocation of β-catenin. Finally, ERK and MEK phosphorylation was reduced in MDA-MB-231 and MCF-7 cells upon treatment with NaB, and less prominently with NaP.

Conclusion

Our study highlights the promising therapeutic potential of NaB and NaP, providing insight into their inhibitory effects on 3D formation, migration, and invasion through EMT regulation and deactivation of MEK/ERK signaling in breast cancer.

The interplay between probiotics and host autophagy: mechanisms of action and emerging insights

Autophagy, a lysosome-dependent protein degradation mechanism, is a highly conserved catabolic process seen in all eukaryotes. This cell protection system, which is present in all tissues and functions at a basic level, can be up- or downregulated in response to various stresses. A disruption in the natural route of the autophagy process is frequently followed by an interruption in the inherent operation of the body's cells and organs. Probiotics are live bacteria that protect the host through various mechanisms. One of the processes through which probiotics exert their beneficial effects on various cells and tissues is autophagy. Autophagy can assist in maintaining host homeostasis by stimulating the immune system and affecting numerous physiological and pathological responses. In this review, we particularly focus on autophagy impairments occurring in several human illnesses and investigate how probiotics affect the autophagy process under various circumstances.Abbreviation: AD: Alzheimer disease; AKT: AKT serine/threonine kinase; AMPK: 5'AMP-activated protein kinase; ATG: autophagy related; CCl4: carbon tetrachloride; CFS: cell-free supernatant; CMA: chaperone-mediated autophagy; CRC: colorectal cancer; EPS: L. plantarum H31 exopolysaccharide; HD: Huntington disease; HFD: high-fat diet; HPV: human papillomavirus; IFNG/IFN-γ: interferon gamma; IL6: interleukin 6; LGG: L. rhamnosus GG; LPS: lipopolysaccharide; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis; PD: Parkinson disease; Pg3G: pelargonidin-3-O-glucoside; PI3K: phosphoinositide 3-kinase; PolyQ: polyglutamine; ROS: reactive oxygen species; SCFAs: short-chain fatty acids; SLAB51: a novel formulation of lactic acid bacteria and bifidobacteria; Slp: surface layer protein (of acidophilus NCFM); SNCA: synuclein alpha; ULK1: unc-51 like autophagy-activating kinase 1; YB: B. longum subsp. infantis YB0411; YFP: yeast fermentate prebiotic.

Postbiotics as Adjuvant Therapy in Cancer Care

Postbiotics are defined as a preparation of inanimate microorganisms and/or their components that confers a health benefit to the host. They range from cell wall fragments to metabolites, bacterial lysates, extracellular vesicles, and short-chain fatty acids (SCFAs). Postbiotics may influence carcinogenesis via a variety of mechanisms. They can promote homeostatic immune responses, reduce inflammation, induce selective cytotoxicity against tumor cells, as well as the enabling the control of tumor cell proliferation and enhancing intestinal epithelial barrier function. Therefore, probiotics can serve as an adjunct strategy in anticancer treatment together with chemotherapy and immunotherapy. Up to now, the only relevant postbiotics used as interventions in oncological patients remain vitamin K molecules, with few phase-II and III trials available. In fact, postbiotics' levels are strictly dependent on the gut microbiota's composition, which may vary between individuals and can be altered under different physiological and pathological conditions. Therefore, the lack of consistent clinical evidence supporting postbiotics' efficacy is due to their poor bioavailability, short half-life, and fluctuating levels. Synbiotics, a mixture of prebiotics and probiotics, are expected to have a more homogeneous bioavailability with respect to postbiotics and may have greater potential for future development. In this review, we focus on the role of postbiotics as an adjuvant therapy in cancer treatment.

Treatment with sodium butyrate induces autophagy resulting in therapeutic benefits for spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3, also known as Machado Joseph disease) is a fatal neurodegenerative disease caused by the expansion of the trinucleotide repeat region within the ATXN3/MJD gene. Mutation of ATXN3 causes formation of ataxin-3 protein aggregates, neurodegeneration, and motor deficits. Here we investigated the therapeutic potential and mechanistic activity of sodium butyrate (SB), the sodium salt of butyric acid, a metabolite naturally produced by gut microbiota, on cultured SH-SY5Y cells and transgenic zebrafish expressing human ataxin-3 containing 84 glutamine (Q) residues to model SCA3. SCA3 SH-SY5Y cells were found to contain high molecular weight ataxin-3 species and detergent-insoluble protein aggregates. Treatment with SB increased the activity of the autophagy protein quality control pathway in the SCA3 cells, decreased the presence of ataxin-3 aggregates and presence of high molecular weight ataxin-3 in an autophagy-dependent manner. Treatment with SB was also beneficial in vivo, improving swimming performance, increasing activity of the autophagy pathway, and decreasing the presence of insoluble ataxin-3 protein species in the transgenic SCA3 zebrafish. Co-treating the SCA3 zebrafish with SB and chloroquine, an autophagy inhibitor, prevented the beneficial effects of SB on zebrafish swimming, indicating that the improved swimming performance was autophagy-dependent. To understand the mechanism by which SB induces autophagy we performed proteomic analysis of protein lysates from the SB-treated and untreated SCA3 SH-SY5Y cells. We found that SB treatment had increased activity of Protein Kinase A and AMPK signaling, with immunoblot analysis confirming that SB treatment had increased levels of AMPK protein and its substrates. Together our findings indicate that treatment with SB can increase activity of the autophagy pathway process and that this has beneficial effects in vitro and in vivo. While our results suggested that this activity may involve activity of a PKA/AMPK-dependent process, this requires further confirmation. We propose that treatment with sodium butyrate warrants further investigation as a potential treatment for neurodegenerative diseases underpinned by mechanisms relating to protein aggregation including SCA3.

Sodium Butyrate Inhibits the Expression of Thymidylate Synthase and Induces Cell Death in Colorectal Cancer Cells

The most commonly used chemotherapy for colorectal cancer (CRC) is the application of 5-fluorouracil (5-FU). Inhibition of thymidylate synthase (TYMS) expression appears to be a promising strategy to overcome the decreased sensitivity to 5-FU caused by high expression of TYMS, which can be induced by 5-FU treatment. Several compounds have been shown to potentially inhibit the expression of TYMS, but it is unclear whether short-chain fatty acids (SCFAs), which are naturally produced by bacteria in the human intestine, can regulate the expression of TYMS. Sodium butyrate (NaB) is the most widely known SCFA for its beneficial effects. Therefore, we investigated the enhancing effects on inhibition of cell viability and induction of apoptosis after co-treatment of NaB with 5-FU in two CRC cell lines, HCT116 and LoVo. This study suggests that the effect of NaB in improving therapeutic sensitivity to 5-FU in CRC cells may result from a mechanism that strongly inhibits the expression of TYMS. This study also shows that NaB inhibits the migration of CRC cells and can cause cell cycle arrest in the G2/M phase. These results suggest that NaB could be developed as a potential therapeutic adjuvant to improve the therapeutic effect of 5-FU in CRC.

Mucosal Microbiome in Patients with Early Bowel Polyps: Inferences from Short-Read and Long-Read 16S rRNA Sequencing

Numerous studies have correlated dysbiosis in stool microbiota with colorectal cancer (CRC); however, fewer studies have investigated the mucosal microbiome in pre-cancerous bowel polyps. The short-read sequencing of variable regions in the 16S rRNA gene has commonly been used to infer bacterial taxonomy, and this has led, in part, to inconsistent findings between studies. Here, we examined mucosal microbiota from patients who presented with one or more polyps, compared to patients with no polyps, at the time of colonoscopy. We evaluated the results obtained using both short-read and PacBio long-read 16S rRNA sequencing. Neither sequencing technology identified significant differences in microbial diversity measures between patients with or without bowel polyps. Differential abundance measures showed that amplicon sequence variants (ASVs) associated with Ruminococcus gnavus and Escherichia coli were elevated in mucosa from polyp patients, while ASVs associated with Parabacteroides merdae, Veillonella nakazawae, and Sutterella wadsworthensis were relatively decreased. Only R. gnavus was consistently identified using both sequencing technologies as being altered between patients with polyps compared to patients without polyps, suggesting differences in technologies and bioinformatics processing impact study findings. Several of the differentially abundant bacteria identified using either sequencing technology are associated with inflammatory bowel diseases despite these patients being excluded from the current study, which suggests that early bowel neoplasia may be associated with a local inflammatory niche.

Therapeutic strategies targeting AMPK-dependent autophagy in cancer cells

Macroautophagy is a health-modifying process of engulfing misfolded or aggregated proteins or damaged organelles, coating these proteins or organelles into vesicles, fusion of vesicles with lysosomes to form autophagic lysosomes, and degradation of the encapsulated contents. It is also a self-rescue strategy in response to harsh environments and plays an essential role in cancer cells. AMP-activated protein kinase (AMPK) is the central pathway that regulates autophagy initiation and autophagosome formation by phosphorylating targets such as mTORC1 and unc-51 like activating kinase 1 (ULK1). AMPK is an evolutionarily conserved serine/threonine protein kinase that acts as an energy sensor in cells and regulates various metabolic processes, including those involved in cancer. The regulatory network of AMPK is complicated and can be regulated by multiple upstream factors, such as LKB1, AKT, PPAR, SIRT1, or noncoding RNAs. Currently, AMPK is being investigated as a novel target for anticancer therapies based on its role in macroautophagy regulation. Herein, we review the effects of AMPK-dependent autophagy on tumor cell survival and treatment strategies targeting AMPK.

Postbiotics in oncology: science or science fiction?

The gut microbiome has been increasingly understood to play a critical role in carcinogenesis and cancer disease progression. The most recent research advancements have shown that different tools of microbiota manipulation contribute to gut microbiome-immune-oncology axis modulation, offering exciting opportunities for targeted interventions aimed at improving the efficacy of established anti-cancer therapy. Postbiotics are a new entry among the biotics showing beneficial effects on human health while not requiring living cells to obtain the health effect and therefore not subjected to food safety rules for live microorganisms. Postbiotics are recently defined as the "preparation of inanimate microorganisms and/or their components that confers a health benefit on the host" and have gradually become the focus of the scientific community. Since the beginning of research on this topic, numerous studies about postbiotics have been proven to strengthen the gut barrier, reduce inflammation, and promote antimicrobial activity. However, research on the potential application of cancer therapy is still at the early stages of its efforts to uncover all the secrets surrounding postbiotics. This review aims to increase our understanding of the anti-cancer effect of postbiotics throughout a "bibliographic journey" on the biological activity of their components, including exopolysaccharides, cell wall fragments, tryptophan metabolites, enzymes, bacterial lysates, extracellular vesicles, and short-chain fatty acids, highlighting their perspective as a new supportive therapeutic method of treatment and identifying the literature gaps where further research is needed.

Sertaconazole nitrate targets IDO1 and regulates the MAPK signaling pathway to induce autophagy and apoptosis in CRC cells

Colorectal cancer (CRC) has become the third most frequently occurring malignant tumor worldwide. It is vital to identify novel, effective targeted treatments while considering side effects and drug resistance in the clinic. Recently, the tryptophan-metabolizing enzyme indole-2, 3-dioxygenase 1 (IDO1) has been widely reported to be overexpressed in CRC, indicating that blocking IDO1 with small-molecule inhibitors may be a promising approach to CRC treatment. In this study, the antifungal drug sertaconazole nitrate (STZ) was repurposed and showed antitumor activity, and therefore, its anticancer effect was further investigated in CRC cells. The SwissTargetPrediction analysis indicated that STZ binding to IDO1 was significantly and highly probable, and STZ was found to downregulate IDO1 in CRC cells in a dose-dependent manner. STZ exhibited considerable antiproliferative activity and induced apoptosis and autophagy in HCT116 and RKO cells. Moreover, based on an RNA-seq analysis, STZ was shown to regulate signal transducer and activator of transcription 3 (STAT3) and the mitogen-activated protein kinase (MAPK) signaling pathways. We discovered that STZ suppressed tumor growth in an HCT116 nude mouse xenograft tumor model without causing evident cytotoxicity. In conclusion, our results reveal that STZ induces antitumor effects in CRC by inhibiting IDO1-modulated autophagy and apoptosis, providing a clue for repurposing STZ as a novel and potentially effective candidate medication for the future treatment of CRC.

Targeted PEGylated Chitosan Nano-complex for Delivery of Sodium Butyrate to Prostate Cancer: An In Vitro Study

Introduction: Cancer remains a challenging issue against human health throughout the world; As a result, introducing novel approaches would be beneficial for cancer treatment. In this research, sodium butyrate (Sb) is one of the effective anti-cancer therapeutics (also a potent survival factor for normal cells) that was used for prostate cancer suppression in the platform of modified chitosan (CS) nano-complex (polyethylene glycol (PEG)-folic acid (FA)-Sb-CS). Methods: Different analytical devices including Fourier transform infrared, dynamic light scattering, high-performance liquid chromatography, scanning electron microscopy, and transmission electron microscopy were applied for the characterization of synthetics. On the other hand, biomedical tests including cell viability assay, molecular and functional assay of apoptosis/autophagy pathways, and cell cycle arrest analysis were potentially implemented on human PC3 (folate receptor-negative prostate cancer) and DU145 (folate receptor-positive prostate cancer) and HFF-1 normal cell lines. Results: The quality of the syntheses was effectively verified, and the size range from 140 to 170 nm was determined for the PEG-CS-FA-Sb sample. Also, 75  ±  5% of drug entrapment efficiency with controlled drug release manner (Sb release of 54.21% and 74.04% for pHs 7.4 and 5.0) were determined for nano-complex. Based on MTT results, PEG-CS-FA-Sb has indicated 72.07% and 33.53% cell viability after 24 h of treatment with 9 mM on PC3 and DU145 cell lines, respectively, which is desirable anti-cancer performance. The apoptotic and autophagy genes overexpression was 15-fold (caspase9), 2.5-fold (BAX), 11-fold (ATG5), 2-fold (BECLIN1), and 3-fold (mTORC1) genes in DU145 cancer cells. More than 50% of cell cycle arrest and 45.05% of apoptosis were obtained for DU145 cancer cells after treatment with nano-complex. Conclusion: Hence, the synthesized Sb-loaded nano-complex could specifically suppress prostate cancer cell growth and induce apoptosis and autophagy in the molecular and cellular phases.

Gut microbiota-derived short-chain fatty acids regulate gastrointestinal tumor immunity: a novel therapeutic strategy?

Tumor immune microenvironment (TIME), a tumor-derived immune component, is proven to be closely related to the development, metastasis, and recurrence of tumors. Gut microbiota and its fermented-metabolites short-chain fatty acids (SCFAs) play a critical role in maintaining the immune homeostasis of gastrointestinal tumors. Consisting mainly of acetate, propionate, and butyrate, SCFAs can interact with G protein-coupled receptors 43 of T helper 1 cell or restrain histone deacetylases (HDACs) of cytotoxic T lymphocytes to exert immunotherapy effects. Studies have shed light on SCFAs can mediate the differentiation and function of regulatory T cells, as well as cytokine production in TIME. Additionally, SCFAs can alter epigenetic modification of CD8⁺ T cells by inhibiting HDACs to participate in the immune response process. In gastrointestinal tumors, the abundance of SCFAs and their producing bacteria is significantly reduced. Direct supplementation of dietary fiber and probiotics, or fecal microbiota transplantation to change the structure of gut microbiota can both increase the level of SCFAs and inhibit tumor development. The mechanism by which SCFAs modulate the progression of gastrointestinal tumors has been elucidated in this review, aiming to provide prospects for the development of novel immunotherapeutic strategies.

Dysbiosis: The first hit for digestive system cancer

Gastrointestinal cancer may be associated with dysbiosis, which is characterized by an alteration of the gut microbiota. Understanding the role of gut microbiota in the development of gastrointestinal cancer is useful for cancer prevention and gut microbiota-based therapy. However, the potential role of dysbiosis in the onset of tumorigenesis is not fully understood. While accumulating evidence has demonstrated the presence of dysbiosis in the intestinal microbiota of both healthy individuals and patients with various digestive system diseases, severe dysbiosis is often present in patients with digestive system cancer. Importantly, specific bacteria have been isolated from the fecal samples of these patients. Thus, the association between dysbiosis and the development of digestive system cancer cannot be ignored. A new model describing this relationship must be established. In this review, we postulate that dysbiosis serves as the first hit for the development of digestive system cancer. Dysbiosis-induced alterations, including inflammation, aberrant immune response, bacteria-produced genotoxins, and cellular stress response associated with genetic, epigenetic, and/or neoplastic changes, are second hits that speed carcinogenesis. This review explains the mechanisms for these four pathways and discusses gut microbiota-based therapies. The content included in this review will shed light on gut microbiota-based strategies for cancer prevention and therapy.

Sodium butyrate in both prevention and supportive treatment of colorectal cancer

Accumulating evidence suggests that selected microbiota-derived metabolites play a significant role in both tumor prevention and supportive treatment of cancer. Short-chain fatty acids (SCFAs), i.e., mainly acetate, proprionate, and butyrate, are one of them. Nowadays, it is known that butyrate is a key microbial metabolite. Therefore, in the current review, we focused on butyrate and sodium butyrate (NaB) in the context of colorectal cancer. Notably, butyrate is characterized by a wide range of beneficial properties/activities. Among others, it influences the function of the immune system, maintains intestinal barrier integrity, positively affects the efficiency of anti-cancer treatment, and may reduce the risk of mucositis induced by chemotherapy. Taking into consideration these facts, we analyzed NaB (which is a salt of butyric acid) and its impact on gut microbiota as well as anti-tumor activity by describing molecular mechanisms. Overall, NaB is available as, for instance, food with special medical purposes (depending on the country's regulation), and its administration seems to be a promising option for colorectal cancer patients.

Lactobacillus (LA-1) and butyrate inhibit osteoarthritis by controlling autophagy and inflammatory cell death of chondrocytes

Osteoarthritis (OA) reduces the quality of life as a result of the pain caused by continuous joint destruction. Inactivated Lactobacillus (LA-1) ameliorated osteoarthritis and protected cartilage by modulating inflammation. In this study, we evaluated the mechanism by which live LA-1 ameliorated OA. To investigate the effect of live LA-1 on OA progression, we administered LA-1 into monosodium iodoacetate (MIA)-induced OA animals. The pain threshold, cartilage damage, and inflammation of the joint synovial membrane were improved by live LA-1. Furthermore, the analysis of intestinal tissues and feces in the disease model has been shown to affect the systems of the intestinal system and improve the microbiome environment. Interestingly, inflammation of the intestinal tissue was reduced, and the intestinal microbiome was altered by live LA-1. Live LA-1 administration led to an increase in the level of Faecalibacterium which is a short-chain fatty acid (SCFA) butyrate-producing bacteria. The daily supply of butyrate, a bacterial SCFA, showed a tendency to decrease necroptosis, a type of abnormal cell death, by inducing autophagy and reversing impaired autophagy by the inflammatory environment. These results suggest that OA is modulated by changes in the gut microbiome, suggesting that activation of autophagy can reduce aberrant cell death. In summary, live LA-1 or butyrate ameliorates OA progression by modulating the gut environment and autophagic flux. Our findings suggest the regulation of the gut microenvironment as a therapeutic target for OA.

Mechanisms shared between cancer, heart failure, and targeted anti-cancer therapies

Heart failure (HF) and cancer are the leading causes of death worldwide and accumulating evidence demonstrates that HF and cancer affect one another in a bidirectional way. Patients with HF are at increased risk for developing cancer, and HF is associated with accelerated tumour growth. The presence of malignancy may induce systemic metabolic, inflammatory, and microbial alterations resulting in impaired cardiac function. In addition to pathophysiologic mechanisms that are shared between cancer and HF, overlaps also exist between pathways required for normal cardiac physiology and for tumour growth. Therefore, these overlaps may also explain the increased risk for cardiotoxicity and HF as a result of targeted anti-cancer therapies. This review provides an overview of mechanisms involved in the bidirectional connection between HF and cancer, specifically focusing upon current 'hot-topics' in these shared mechanisms. It subsequently describes targeted anti-cancer therapies with cardiotoxic potential as a result of overlap between their anti-cancer targets and pathways required for normal cardiac function.

The role and mechanism of butyrate in the prevention and treatment of diabetic kidney disease

Diabetic kidney disease (DKD) remains the leading cause of the end-stage renal disease and is a major burden on the healthcare system. The current understanding of the mechanisms responsible for the progression of DKD recognizes the involvement of oxidative stress, low-grade inflammation, and fibrosis. Several circulating metabolites that are the end products of the fermentation process, released by the gut microbiota, are known to be associated with systemic immune-inflammatory responses and kidney injury. This phenomenon has been recognized as the “gut–kidney axis.” Butyrate is produced predominantly by gut microbiota fermentation of dietary fiber and undigested carbohydrates. In addition to its important role as a fuel for colonic epithelial cells, butyrate has been demonstrated to ameliorate obesity, diabetes, and kidney diseases via G-protein coupled receptors (GPCRs). It also acts as an epigenetic regulator by inhibiting histone deacetylase (HDAC), up-regulation of miRNAs, or induction of the histone butyrylation and autophagy processes. This review aims to outline the existing literature on the treatment of DKD by butyrate in animal models and cell culture experiments, and to explore the protective effects of butyrate on DKD and the underlying molecular mechanism.

Microbial Metabolites in the Maturation and Activation of Dendritic Cells and Their Relevance for Respiratory Immunity

The respiratory tract is a gateway for viruses and bacteria from the external environment to invade the human body. Critical to the protection against these invaders are dendritic cells (DCs) - a group of highly specialized myeloid cells that monitors the lung microenvironment and relays contextual and antigenic information to T cells. Following the recognition of danger signals and/or pathogen molecular associated patterns in the lungs, DCs undergo activation. This process arms DCs with the unique ability to induce the proliferation and differentiation of T cells responding to matching antigen in complex with MHC molecules. Depending on how DCs interact with T cells, the ensuing T cell response can be tolerogenic or immunogenic and as such, the susceptibility and severity of respiratory infections is influenced by the signals DCs receive, integrate, and then convey to T cells. It is becoming increasingly clear that these facets of DC biology are heavily influenced by the cellular components and metabolites produced by the lung and gut microbiota. In this review, we discuss the roles of different DC subsets in respiratory infections and outline how microbial metabolites impact the development, propensity for activation and subsequent activation of DCs. In particular, we highlight these concepts in the context of respiratory immunity.

Liver Metastatic Breast Cancer: Epidemiology, Dietary Interventions, and Related Metabolism

The median overall survival of patients with metastatic breast cancer is only 2-3 years, and for patients with untreated liver metastasis, it is as short as 4-8 months. Improving the survival of women with breast cancer requires more effective anti-cancer strategies, especially for metastatic disease. Nutrients can influence tumor microenvironments, and cancer metabolism can be manipulated via a dietary modification to enhance anti-cancer strategies. Yet, there are no standard evidence-based recommendations for diet therapies before or during cancer treatment, and few studies provide definitive data that certain diets can mediate tumor progression or therapeutic effectiveness in human cancer. This review focuses on metastatic breast cancer, in particular liver metastatic forms, and recent studies on the impact of diets on disease progression and treatment.

Changes of gut microbiota in diabetic nephropathy and its effect on the progression of kidney injury

PURPOSE

We aimed to illustrate gut microbiota and short chain fatty acid (SCFA) levels in diabetic nephropathy (DN) patients, and investigate the mechanism of sodium butyrate in diabetic mellitus (DM) rats.

METHODS

Gut microbiota and serum SCFA levels were measured by 16S rDNA and GC-MS. After being built by streptozotocin (DM rats), the DM rats were administered 300 mg/kg sodium butyrate for 12 weeks (DM + BU rats). Gut microbiota, serum and fecal butyrate level were measured. RT-PCR, WB and transmission electron microscopy were performed to explore LC3mRNA or LC3B protein expression, and autophagosomes in kidney tissues. AMPK/mTOR protein expression in renal tissue were also measured.

RESULTS

The gut microbial dysbiosis was found in DM and DN groups, and some SCFAs-producing bacteria were decreased in DN group. The serum butyrate concentrations were lower in SCFA-DN group compared with SCFA-HC group and SCFA-DM group in the other cohort. Serum butyrate level was positively correlated with eGFR. Sodium butyrate increased serum and fecal butyrate levels, and improved the enlargement of glomerular area and fibronectin and collagen IV expressions in renal tissues in DM + BU rats. The LC3 mRNA, LC3BII/I ratio and number of autophagosomes were increased in renal tissue of DM + BU rats. Higher p-AMPK/AMPK ratio and lower p-mTOR/ mTOR ratio were shown in renal tissue of DM + BU rats compared with DM rats.

CONCLUSIONS

We found the decrease in SCFAs-producing bacteria and low SCFAs concentrations in DN patients. Oral butyrate supplementation may improve kidney injury in DM rats, possibly by increasing autophagy via activating AMPK/mTOR pathway.

Sodium Butyrate Ameliorates Oxidative Stress-Induced Intestinal Epithelium Barrier Injury and Mitochondrial Damage through AMPK-Mitophagy Pathway

Sodium butyrate has gained increasing attention for its vast beneficial effects. However, whether sodium butyrate could alleviate oxidative stress-induced intestinal dysfunction and mitochondrial damage of piglets and its underlying mechanism remains unclear. The present study used a hydrogen peroxide- (H₂O₂-) induced oxidative stress model to study whether sodium butyrate could alleviate oxidative stress, intestinal epithelium injury, and mitochondrial dysfunction of porcine intestinal epithelial cells (IPEC-J2) in AMPK-mitophagy-dependent pathway. The results indicated that sodium butyrate alleviated the H₂O₂-induced oxidative stress, decreased the level of reactive oxygen species (ROS), increased mitochondrial membrane potential (MMP), mitochondrial DNA (mtDNA), and mRNA expression of genes related to mitochondrial function, and inhibited the release of mitochondrial cytochrome c (Cyt c). Sodium butyrate reduced the protein expression of recombinant NLR family, pyrin domain-containing protein 3 (NLRP3) and fluorescein isothiocyanate dextran 4 kDa (FD4) permeability and increased transepithelial resistance (TER) and the protein expression of tight junction. Sodium butyrate increased the expression of light-chain-associated protein B (LC3B) and Beclin-1, reduced the expression of P62, and enhanced mitophagy. However, the use of AMPK inhibitor or mitophagy inhibitor weakened the protective effect of sodium butyrate on mitochondrial function and intestinal epithelium barrier function and suppressed the induction effect of sodium butyrate on mitophagy. In addition, we also found that after interference with AMPKα, the protective effect of sodium butyrate on IPEC-J2 cells treated with H₂O₂ was suppressed, indicating that AMPKα is necessary for sodium butyrate to exert its protective effect. In summary, these results revealed that sodium butyrate induced mitophagy by activating AMPK, thereby alleviating oxidative stress, intestinal epithelium barrier injury, and mitochondrial dysfunction induced by H₂O₂.

Role of Intestinal Alkaline Phosphatase in Innate Immunity

Intestinal alkaline phosphatase (IAP) is a multi-functional protein that has been demonstrated to primarily protect the gut. The role of IAP in maintaining intestinal homeostasis is underscored by the observation that IAP expression is defective in many gastrointestinal-related disorders such as inflammatory bowel disease IBD, necrotizing enterocolitis, and metabolic syndrome and that exogenous IAP supplementation improves the outcomes associated with these disorders. Additionally, studies using transgenic IAP-knock out (IAP-KO) mouse models further support the importance of the defensive role of IAP in the intestine. Supplementation of exogenous IAP and cellular overexpression of IAP have also been used in vitro to dissect out the downstream mechanisms of this protein in mammalian cell lines. Some of the innate immune functions of IAP include lipopolysaccharide (LPS) detoxification, protection of gut barrier integrity, regulation of gut microbial communities and its anti-inflammatory roles. A novel function of IAP recently identified is the induction of autophagy. Due to its critical role in the gut physiology and its excellent safety profile, IAP has been used in phase 2a clinical trials for treating conditions such as sepsis-associated acute kidney injury. Many excellent reviews discuss the role of IAP in physiology and pathophysiology and here we extend these to include recent updates on this important host defense protein and discuss its role in innate immunity via its effects on bacteria as well as on host cells. We will also discuss the relationship between IAP and autophagy and how these two pathways may act in concert to protect the gut.

Effect of butyrate, a bacterial by-product, on the viability and ICAM-1 expression/production of human vascular endothelial cells: Role in infectious pulpal/periapical diseases

AIM

To investigate the effects of butyric acid (BA), a metabolic product generated by pulp and root canal pathogens, on the viability and intercellular adhesion molecule-1 (ICAM-1) production of endothelial cells, which are crucial to angiogenesis and pulpal/periapical wound healing.

METHODOLOGY

Endothelial cells were exposed to butyrate with/without inhibitors. Cell viability, apoptosis and reactive oxygen species (ROS) were evaluated using an MTT assay, PI/annexin V and DCF fluorescence flow cytometry respectively. RNA and protein expression was determined using a polymerase chain reaction assay and Western blotting or immunofluorescent staining. Soluble ICAM-1 (sICAM-1) was measured using an enzyme-linked immunosorbent assay. The quantitative results were expressed as mean ± standard error (SE) of the mean. The data were analysed using a paired Student's t-test where necessary. A p-value ≤0.05 was considered to indicate a statistically significant difference between groups.

RESULTS

Butyrate (>4 mM) inhibited cell viability and induced cellular apoptosis and necrosis. It inhibited cyclin B1 but stimulated p21 and p27 expression. Butyrate stimulated ROS production and hemeoxygenase-1 (HO-1) expression as well as activated the Ac-H3, p-ATM, p-ATR, p-Chk1, p-Chk2, p-p38 and p-Akt expression of endothelial cells. Butyrate stimulated ICAM-1 mRNA/protein expression and significant sICAM-1 production (p < .05). Superoxide dismutase, 5z-7oxozeaenol, SB203580 and compound C (p <  .05), but not ZnPP, CGK733, AZD7762 or LY294002, attenuated butyrate cytotoxicity to endothelial cells. Notably, little effect on butyrate-stimulated sICAM-1 secretion was found. Valproic acid, phenylbutyrate and trichostatin (three histone deacetylase inhibitors) significantly induced sICAM-1 production (p < .05).

CONCLUSION

Butyric acid inhibited proliferation, induced apoptosis, stimulated ROS and HO-1 production and increased ICAM-1 mRNA expression and protein synthesis in endothelial cells. Cell viability affected by BA was diminished by some inhibitors; however, the increased sICAM-1 secretion by BA was not affected by any of the tested inhibitors. These results facilitate understanding of the pathogenesis, prevention and treatment of pulpal/periapical diseases.

Postbiotics, Metabolic Signaling, and Cancer

Postbiotics are health-promoting microbial metabolites delivered as a functional food or a food supplement. They either directly influence signaling pathways of the body or indirectly manipulate metabolism and the composition of intestinal microflora. Cancer is the second leading cause of death worldwide and even though the prognosis of patients is improving, it is still poor in the substantial part of the cases. The preventable nature of cancer and the importance of a complex multi-level approach in anticancer therapy motivate the search for novel avenues of establishing the anticancer environment in the human body. This review summarizes the principal findings demonstrating the usefulness of both natural and synthetic sources of postbotics in the prevention and therapy of cancer. Specifically, the effects of crude cell-free supernatants, the short-chain fatty acid butyrate, lactic acid, hydrogen sulfide, and β-glucans are described. Contradictory roles of postbiotics in healthy and tumor tissues are highlighted. In conclusion, the application of postbiotics is an efficient complementary strategy to combat cancer.

A gut butyrate-producing bacterium Butyricicoccus pullicaecorum regulates short-chain fatty acid transporter and receptor to reduce the progression of 1,2-dimethylhydrazine-associated colorectal cancer

Gut microbes influence tumor development and progression in the intestines and may provide a novel paradigm for the treatment of colorectal cancer (CRC). Gut dysbiosis may be associated with the development and progression of CRC. Identifying the interactions between the colonic tract and gut microbiota may provide novel information relevant to CRC prevention. The present study examined the effects of butyrate-producing Butyricicoccus pullicaecorum (B. pullicaecorum) on mice with 1,2-dimethylhydrazine (DMH)-induced CRC and the microbial metabolite of B. pullicaecorum on CRC cells. Immunohistochemical staining of the mouse colon tissues and reverse transcription PCR of CRC cells were used to determine the protein and mRNA expression levels of the short-chain fatty acid (SCFA) transporter solute carrier family 5 member 8 (SLC5A8) and G-protein-coupled receptor 43 (GPR43). In CRC-bearing mice fed B. pullicaecorum, DMH-induced CRC regressed, body weight increased and serum carcinoembryonic antigen levels decreased. Notably, SLC5A8 and GPR43 were diffusely and moderately to strongly expressed in the neoplastic epithelial cells and underlying muscularis propria in the colons of the mice. In conclusion, administration of B. pullicaecorum or its metabolites improved the clinical outcome of CRC by activating the SCFA transporter and/or receptor. These results indicated that B. pullicaecorum was a probiotic with anti-CRC potential.

Sodium Butyrate Selectively Kills Cancer Cells and Inhibits Migration in Colorectal Cancer by Targeting Thioredoxin-1

BACKGROUND

Sodium butyrate (NaB) is a short-chain fatty acid which is produced by bacterial fermentation of nondigestible dietary fiber and has been reported to exert anti-tumor effects in many tumors including colorectal cancer (CRC). However, the role of thioredoxin-1 (Trx-1) in NaB-induced anti-tumor effect has not been completely clarified.

MATERIALS AND METHODS

Effects of NaB on the growth of CRC cell lines HT29 and SW480 were detected by the Cell Counting Kit-8 (CCK-8) and colony formation assays. The apoptotic cells were determined by flow cytometry, and cell migration was assessed by a Transwell assay. Western blot analysis was used to test the Trx-1 and epithelial-to-mesenchymal transition (EMT)-related proteins level. Reactive oxygen species (ROS) level was determined and N-acetylcysteine (NAC) recovery experiment was performed in CRC cells. In addition, mice xenograft model was established to test the effect of NaB on CRC growth in vivo. Further, the effects of NaB on CRC cells with overexpression or knockdown were tested by the CCK-8 and Transwell assays.

RESULTS

NaB treatment significantly inhibited cell growth and decreased Trx-1 protein expression in CRC cells but not in normal colon epithelial cells. NaB also induced apoptosis, inhibited colony formation, migration and EMT in CRC cells. Besides, NaB increased ROS level in CRC cells and NAC reversed NaB-induced inhibition of cell proliferation. Moreover, downregulation of Trx-1 significantly enhanced NaB-induced inhibitory effects on cell growth and migration, whereas overexpression of Trx-1 attenuated NaB-induced inhibitory effects on growth and migration in CRC cells.

CONCLUSION

These findings indicate that the NaB-mediated anti-tumor effects on CRC cells are related to downregulation of Trx-1.

Effect of Short Chain Fatty Acids on Age-Related Disorders

Recent studies have indicated a prominent role of intestinal microbiota in regulation of several physiological aspects of the host including development and activation of the immune system and control of metabolism. In this review, we focused our discussion on bacterial metabolites produced from dietary fiber fermentation called short-chain fatty acids, which act as a link between the microbiota and host cells. Specifically, we described how modifications in their intestinal levels are associated with development of age-related pathologies including metabolic diseases and type 2 diabetes, hypertension, cardiovascular and neurodegenerative diseases. We also highlight their impact on the development of cancer.

Sodium butyrate causes α-synuclein degradation by an Atg5-dependent and PI3K/Akt/mTOR-related autophagy pathway

Aggregation of α-Synuclein is central to the pathogenesis of Parkinson's disease (PD). However, these α-Synuclein inclusions are not only present in brain, but also in gut. Enteroendocrine cells (EECs), which are directly exposed to the gut lumen, can express α-Synuclein and directly connect to α-Synuclein-containing nerves. Dysbiosis of gut microbiota and microbial metabolite short-chain fatty acids (SCFAs) has been implicated as a driver for PD. Butyrate is an SCFA produced by the gut microbiota. Our aim was to demonstrate how α-Synuclein expression in EECs responds to butyrate stimulation. Interestingly, we found that sodium butyrate (NaB) increases α-Synuclein mRNA expression, enhances Atg5-mediated autophagy (increased LC3B-II and decreased SQSTM1 (also known as p62) expression) in murine neuroendocrine STC-1 cells. Further, α-Synuclein mRNA was decreased by the inhibition of autophagy by using inhibitor bafilomycin A1 or by silencing Atg5 with siRNA. Moreover, the PI3K/Akt/mTOR pathway was significantly inhibited and cell apoptosis was activated by NaB. Conditioned media from NaB-stimulated STC-1 cells induced inflammation in SH-SY5Y cells. Collectively, NaB causes α-Synuclein degradation by an Atg5-dependent and PI3K/Akt/mTOR-related autophagy pathway.

Wheat Bran for Colon Cancer Prevention: The Synergy between Phytochemical Alkylresorcinol C21 and Intestinal Microbial Metabolite Butyrate

There is convincing evidence that consuming whole grains (WGs) may decrease the risk of colorectal cancer (CRC). Wheat bran (WB) is a rich source of dietary fiber and phytochemicals with health-promoting properties. However, the active components especially the interaction between different components in WG wheat have not been fully explored. Here, we investigated whether one of the major WB phytochemicals, alkylresorcinol (AR) C21, and the major active intestinal microbial metabolite of fiber, butyrate, could synergistically suppress human colon cancer cells. Our results demonstrated for the first time that the combination of C21 and butyrate synergistically inhibited the growth of human colon cancer cells and induced apoptosis. Further mechanistic studies demonstrated that the cotreatment of C21 and butyrate induced significant up-regulations in cleaved Poly(ADP-ribose) polymerase (PARP), cleaved caspase 3, p53 upregulated modulator of apoptosis (PUMA), cytochrome C, lipid-conjugated membrane-bound form of microtubule-associated protein 1A/1B-light chain 3 (LC3-II), and C/EBP homologous protein (CHOP) expressions, indicating the synergistic anticancer effects of C21 and butyrate were associated with induction of apoptosis, autophagy, and ER stress pathways. Notably, the C21 concentrations in the large intestinal tract of mice treated with human relevant doses of C21, were from 0.86 to 1.78 μmol/g, suggesting the C21 doses used in vitro may be achievable after daily WG wheat intake. These results provide novel insights into the dietary prevention of CRC regarding the potential interaction of bioactive WG wheat phytochemicals and the microbial metabolites of fiber.

Glioblastoma: Role of Mitochondria N-acetylserotonin/Melatonin Ratio in Mediating Effects of miR-451 and Aryl Hydrocarbon Receptor and in Coordinating Wider Biochemical Changes

A wide array of different factors and processes have been linked to the biochemical underpinnings of glioblastoma multiforme (GBM) and glioblastoma stem cells (GSC), with no clear framework in which these may be integrated. Consequently, treatment of GBM/GSC is generally regarded as very poor. This article provides a framework that is based on alterations in the regulation of the melatonergic pathways within mitochondria of GBM/GSC. It is proposed that the presence of high levels of mitochondria-synthesized melatonin is toxic to GBM/GSC, with a number of processes in GBM/GSC acting to limit melatonin’s synthesis in mitochondria. One such factor is the aryl hydrocarbon receptor, which increases cytochrome P450 (CYP)1b1 in mitochondria, leading to the ‘backward’ conversion of melatonin to N-acetylserotonin (NAS). N-acetylserotonin has some similar, but some important differential effects compared with melatonin, including its activation of the tyrosine receptor kinase B (TrkB) receptor. TrkB activation is important to GBM/GSC survival and proliferation. A plethora of significant, but previously disparate, data on GBM/GSC can then be integrated within this framework, including miR-451, AMP-activated protein kinase (AMPK)/mTOR, 14-3-3 proteins, sirtuins, tryptophan 2,3-dioxygenase, and the kynurenine pathways. Such a conceptualization provides a framework for the development of more effective treatment for this poorly managed condition.

Corilagin alleviates acetaminophen-induced hepatotoxicity via enhancing the AMPK/GSK3β-Nrf2 signaling pathway

Background

Acetaminophen (APAP) overdose-induced acute liver failure (ALF) is mainly resulted from uncontrolled oxidative stress. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a key antioxidant transcription factor, is essential for alleviating APAP-induced hepatotoxicity. Corilagin (Cori) is a natural polyphenol compound that possesses effective antioxidant activity; however, the protective effect of Cori on APAP-induced hepatotoxicity is still unknown. The current study aimed to explore whether Cori could mitigate hepatotoxicity caused by APAP and the underlying molecular mechanisms of action.

Methods

Cell counting kit-8 (CCK-8) assays, Western blotting analysis, dual-luciferase reporter assays, a mouse model, CRISPR/Cas9 knockout technology, and hematoxylin-eosin (H & E) staining were employed to explore the mechanisms by which Cori exerts a protective effect on hepatotoxicity in HepG2 cells and in a mouse model.

Results

Our findings suggested that Cori efficiently decreased APAP-triggered the generation of reactive oxygen species (ROS) and cell death in HepG2 cells. Additionally, Cori significantly induced the expression of several antioxidant enzymes, and this induced expression was closely linked to the upregulation of Nrf2, inhibition of Keap1 protein expression, and promotion of antioxidant response element (ARE) activity in HepG2 cells. Moreover, Cori clearly induced the phosphorylation of AMP-activated protein kinase (AMPK), glycogen synthase kinase-3β (GSK3β), liver kinase B1 (LKB1) and acetyl-CoA carboxylase (ACC). Furthermore, Cori-mediated GSK3β inactivation, Nrf2 upregulation and cytoprotection were abolished by an AMPK inhibitor (Compound C) in HepG2 cells. Lastly, we found that Cori inhibited APAP-induced hepatotoxicity and mediated the expression of many antioxidant enzymes; these results were reversed in Nrf2 ^−/− HepG2 cells. In vivo, Cori significantly protected against APAP-induced ALF by reducing mortality and alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, attenuating histopathological liver changes, inhibiting myeloperoxidase (MPO) and malondialdehyde (MDA) levels, and increasing the superoxide dismutase (SOD) content and GSH-to-GSSG ratio as well as suppressing c-jun N-terminal kinase (JNK) phosphorylation. However, Cori-induced reductions in mortality, AST and ALT levels, and histopathological liver changes induced by APAP were clearly abrogated in Nrf2-deficienct mice.

Conclusions

These findings principally indicated that Cori effectively protects against APAP-induced ALF via the upregulation of the AMPK/GSK3β-Nrf2 signaling pathway.