Short-chain fatty acids exert opposite effects on the expression and function of p-glycoprotein and breast cancer resistance protein in rat intestine

Different Short-Chain Fatty Acids Unequally Modulate Intestinal Homeostasis and Reverse Obesity-Related Symptoms in Lead-Exposed High-Fat Diet Mice

Our previous study showed that heavy metal lead (Pb) exposure exacerbates high-fat-diet (HFD)-induced metabolic damage and significantly depletes the gut microbiota-derived metabolite short-chain fatty acid (SCFA) levels. However, it remains unclear whether SCFA is a key metabolite involved in accelerating adverse consequences after Pb exposure. In this study, we explored the effects of exogenous supplementation of acetate, propionate, and butyrate on a metabolic disorder model in Pb-exposed HFD mice. We found that three SCFA interventions attenuated glycolipid metabolism disorders and liver damage, with butyrate performing the best effects in improving obesity-related symptoms. All three SCFA promoted the abundance of Muribaculaceae and Muribaculum, acetate specifically enriched Christensenellaceae, Blautia, and Ruminococcus, and butyrate specifically enriched Parasutterella, Rikenella, Prevotellaceae_UCG-001, and Bacteroides, which contributed to the positive promotion of SCFA production forming a virtuous cycle. Besides, butyrate inhibited Gram-negative bacteria Escherichia-Shigella. All of these events alleviated the intestinal Th17/Treg imbalance and inflammatory response through crosstalk between the G protein-coupled receptor (GPR)/histone deacetylase 3 (HDAC3) and lipopolysaccharide (LPS)/toll-like receptors 4 (TLR4)/nuclear factor κ-B (NF-κB) pathways and ultimately improved the intestinal barrier function. SCFA further upregulated the monocarboxylate transporter 1 (MCT1) and GPR43/adenosine 5'-monophosphate-activated protein kinase (AMPK) pathways to inhibit hepatic lipid accumulation. Overall, SCFA, especially butyrate, is an effective modulator to improve metabolic disorders in obese individuals exposed to heavy metals by targeting gut microecology.

Short-chain fatty acids mitigate Methamphetamine-induced hepatic injuries in a Sigma-1 receptor-dependent manner

Methamphetamine (Meth) is a potent psychostimulant with well-established hepatotoxicity. Gut microbiota-derived short-chain fatty acids (SCFAs) have been reported to yield beneficial effects on the liver. In this study, we aim to further reveal the mechanisms of Meth-induced hepatic injuries and investigate the potential protective effects of SCFAs. Herein, mice were intraperitoneally injected with 15 mg/kg Meth to induce hepatic injuries. The composition of fecal microbiota and SCFAs was profiled using 16 S rRNA sequencing and Gas Chromatography/Mass Spectrometry (GC/MS) analysis, respectively. Subsequently, SCFAs supplementation was performed to evaluate the protective effects against hepatic injuries. Additionally, Sigma-1 receptor knockout (S1R-/-) mice and fluvoxamine (Flu), an agonist of S1R, were introduced to investigate the mechanisms underlying the protective effects of SCFAs. Our results showed that Meth activated S1R and induced hepatic autophagy, inflammation, and oxidative stress by stimulating the MAPK/ERK pathway. Meanwhile, Meth disrupted SCFAs product-related microbiota, leading to a reduction in fecal SCFAs (especially Acetic acid and Propanoic acid). Accompanied by the optimization of gut microbiota, SCFAs supplementation normalized S1R expression and ameliorated Meth-induced hepatic injuries by repressing the MAPK/ERK pathway. Effectively, S1R knockout repressed Meth-induced activation of the MAPK/ERK pathway and further ameliorated hepatic injuries. Finally, the overexpression of S1R stimulated the MAPK/ERK pathway and yielded comparable adverse phenotypes to Meth administration. These findings suggest that Meth-induced hepatic injuries relied on the activation of S1R, which could be alleviated by SCFAs supplementation. Our study confirms the crucial role of S1R in Meth-induced hepatic injuries for the first time and provides a potential preemptive therapy.

Changes in the fecal microbiota of breast cancer patients based on 16S rRNA gene sequencing: a systematic review and meta-analysis

PURPOSE

Breast cancer (BC) is a devastating disease for women. Microbial influences may be involved in the development and progression of breast cancer. This study aimed to investigate the difference in intestinal flora abundance between breast cancer patients and healthy controls (HC) based on previous 16S ribosomal RNA (rRNA) gene sequencing results, which have been scattered and inconsistent in previous studies.

MATERIALS AND METHODS

In agreement with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we searched for pertinent literature in Pubmed, Embase, Cochrane Library, and Web of Science databases from build until February 1, 2023. Relative abundance, diversity of intestinal microflora by level, microbial composition, community structure, diversity index, and other related data were extracted. We used a fixed or random effects model for data analysis. We also conducted funnel plot analysis, sensitivity analysis, Egger's, and Begg's tests to assess the bias risk.

RESULTS

A total of ten studies involving 734 BC patients were enrolled. It was pointed out that there were significant differences in the Chao index between BC and HC in these studies [SMD = - 175.44 (95% CI - 246.50 to - 104.39)]. The relative abundance of Prevotellaceae [SMD = - 0.27 (95% CI - 0.39 to - 0.15)] and Bacteroides [SMD = 0.36 (95% CI 0.23-0.49)] was significantly different. In the included articles, the relative abundance of Prevotellaceae, Ruminococcus, Roseburia inulinivorans, and Faecalibacterium prausnitzii decreased in BC. Accordingly, the relative richness of Erysipelotrichaceae was high in BC.

CONCLUSIONS

This observational meta-analysis revealed that the changes in gut microbiota were correlated with BC, and the changes in some primary fecal microbiota might affect the beginning of breast cancer.

Roles of PPAR activation in cancer therapeutic resistance: Implications for combination therapy and drug development

Therapeutic resistance is a major obstacle to successful treatment or effective containment of cancer. Peroxisome proliferator-activated receptors (PPARs) play an essential role in regulating energy homeostasis and determining cell fate. Despite of the pleiotropic roles of PPARs in cancer, numerous studies have suggested their intricate relationship with therapeutic resistance in cancer. In this review, we provided an overview of the roles of excessively activated PPARs in promoting resistance to modern anti-cancer treatments, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy. The mechanisms through which activated PPARs contribute to therapeutic resistance in most cases include metabolic reprogramming, anti-oxidant defense, anti-apoptosis signaling, proliferation-promoting pathways, and induction of an immunosuppressive tumor microenvironment. In addition, we discussed the mechanisms through which activated PPARs lead to multidrug resistance in cancer, including drug efflux, epithelial-to-mesenchymal transition, and acquisition and maintenance of the cancer stem cell phenotype. Preliminary studies investigating the effect of combination therapies with PPAR antagonists have suggested the potential of these antagonists in reversing resistance and facilitating sustained cancer management. These findings will provide a valuable reference for further research on and clinical translation of PPAR-targeting treatment strategies.

Natural medicinal compounds target signal transduction pathways to overcome ABC drug efflux transporter-mediated multidrug resistance in cancer

ATP-binding cassette (ABC) transporters such as ABCB1, ABCG2, and ABCC1 are the major players in drug efflux-mediated multidrug resistance (MDR), which severely affects the efficacy of chemotherapy. Several synthetic compounds block the drug transport by ABC transporters; however, they exhibit a narrow therapeutic window, and produce side effects in non-target normal tissues. Conversely, the downregulation of the expression of ABC drug transporters seems to be a promising strategy to reverse MDR in cancer cells. Several signaling pathways, such as NF-κB, STAT3, Gli, NICD, YAP/TAZ, and Nrf2 upregulate the expression of ABC drug transporters in drug-resistant cancers. Recently, natural medicinal compounds have gained importance to overcome the ABC drug-efflux pump-mediated MDR in cancer. These compounds target transcription factors and the associated signal transduction pathways, thereby downregulating the expression of ABC transporters in drug-resistant cancer cells. Several potent natural compounds have been identified as lead candidates to synergistically enhance chemotherapeutic efficacy, and a few of them are already in clinical trials. Therefore, modulation of signal transduction pathways using natural medicinal compounds for the reversal of ABC drug transporter-mediated MDR in cancer is a novel approach for improving the efficiency of the existing chemotherapeutics. In this review, we discuss the modulatory role of natural medicinal compounds on cellular signaling pathways that regulate the expression of ABC transporters in drug-resistant cancer cells.

Effect of acetate supplementation on traumatic stress-induced behavioral impairments in male rats

Gut microbiota and their metabolites have emerged as key players in the pathogenesis of neuropsychiatric disorders. Recently, we demonstrated that animals susceptible to Single Prolonged Stress (SPS) have an overall pro-inflammatory gut microbiota and significantly lower cecal acetate levels than SPS-resilient rats, which correlated inversely with the anxiety index. Here, we investigated whether the microbial metabolite, acetate, could ameliorate SPS-triggered impairments. Male rats were randomly divided into unstressed controls or groups exposed to SPS. The groups received continued oral supplementation of either 150 mM of sodium acetate or 150 mM of sodium chloride-matched water. Two weeks after SPS, a battery of behavioral tests was performed, and the animals were euthanized the following day. While not affecting the unstressed controls, acetate supplementation reduced the impact of SPS on body weight gain and ameliorated SPS-induced anxiety-like behavior and the impairments in social interaction, but not depressive-like behavior. These changes were accompanied by several beneficial effects of acetate supplementation. Acetate alleviated the stress response by reducing urinary epinephrine levels, induced epigenetic modification by decreasing histone deacetylase (HDAC2) gene expression, inhibited neuroinflammation by reducing the density of Iba1+ cells and the gene expression of IL-1ß in the hippocampus, and increased serum β-hydroxybutyrate levels. The findings reveal a causal relationship between oral acetate treatment and mitigation of several SPS-induced behavioral impairments. Mechanistically, it impacted neuronal and metabolic pathways including changes in stress response, epigenetic modifications, neuroinflammation and showed novel link to ketone body production. The study demonstrates the preventive-therapeutic potential of acetate supplementation to alleviate adverse responses to traumatic stress.

Discovery of a novel small molecule with efficacy in protecting against inflammation in vitro and in vivo by enhancing macrophages activation

Immune response and inflammation highly contribute to many metabolic syndromes such as inflammatory bowel disease (IBD), ageing and cancer with disruption of host metabolic homeostasis and the gut microbiome. Icariin-1 (GH01), a small-molecule flavonoid derived from Epimedium, has been shown to protect against systemic inflammation. However, the molecular mechanisms by which GH01 ameliorates ulcerative colitis via regulation of microbiota-mediated macrophages polarization remain elusive. In this study, we found that GH01 effectively ameliorated dextran sulfate sodium (DSS)-induced colitis symptoms in mice. Disruption of intestinal barrier function, commensal microbiota and its metabolites were also significantly restored by GH01 in a dose-dependent manner. Of note, we also found that GH01 enhanced phagocytic ability of macrophages and switched macrophage phenotype from M1 to M2 both in vitro and in vivo. Such macrophage polarization was highly associated with intestinal barrier integrity and the gut microbial community. Consequently, GH01 exhibited strong anti-inflammatory capacity by inhibiting TLR4 and NF-κB pathways and proinflammatory factors (IL-6). These findings suggested that GH01 might be a potential nutritional intervention strategy for IBD treatment with the gut microbial community-meditated macrophage as the therapeutic targets.

Short-chain fatty acids in diseases

Short-chain fatty acids (SCFAs) are the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract. The absorption of SCFAs is mediated by substrate transporters, such as monocarboxylate transporter 1 and sodium-coupled monocarboxylate transporter 1, which promote cellular metabolism. An increasing number of studies have implicated metabolites produced by microorganisms as crucial executors of diet-based microbial influence on the host. SCFAs are important fuels for intestinal epithelial cells (IECs) and represent a major carbon flux from the diet, that is decomposed by the gut microbiota. SCFAs play a vital role in multiple molecular biological processes, such as promoting the secretion of glucagon-like peptide-1 by IECs to inhibit the elevation of blood glucose, increasing the expression of G protein-coupled receptors such as GPR41 and GPR43, and inhibiting histone deacetylases, which participate in the regulation of the proliferation, differentiation, and function of IECs. SCFAs affect intestinal motility, barrier function, and host metabolism. Furthermore, SCFAs play important regulatory roles in local, intermediate, and peripheral metabolisms. Acetate, propionate, and butyrate are the major SCFAs, they are involved in the regulation of immunity, apoptosis, inflammation, and lipid metabolism. Herein, we review the diverse functional roles of this major class of bacterial metabolites and reflect on their ability to affect intestine, metabolic, and other diseases. Video Abstract.

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.

Protective effect of sodium butyrate on intestinal barrier damage and uric acid reduction in hyperuricemia mice

PURPOSE

The goal of this study was to examine the role of sodium butyrate in preserving the intestinal mucosal barrier and reducing hyperuricemia (HUA).

METHODS

First, we established a mouse model of HUA via intraperitoneal injection of potassium oxonate together with a yeast-rich diet to detect the levels of serum uric acid (UA) and fecal short-chain fatty acids (SCFAs). Then, in vitro, different concentrations of UA and sodium butyrate (NaB) were used to treat LS174T and Caco2 cells. The effects of UA and NaB on the gut barrier were determined based on the expression levels of MUC2, ZO-1, and Occludin.Finally, C57BL/6 mice were used to model HUA, and these mice were administered 200 mg·kg^-1·d^-1 NaB by gavage to counter the HUA. The effect of NaB on HUA in the intestinal tract was elucidated by determining serum UA levels, inflammatory parameters, epithelial barrier integrity, and via histological analysis.

RESULTS

The data showed that the content of fecal SCFAs in HUA mice decreased. Additionally, in LS174T and Caco2 cells, NaB reversed the decrease of ZO-1, Occludin, and MUC2 protein expression caused by high UA levels. Furthermore, NaB decreased serum UA of HUA mice, and reversed both the decreased expression of MUC2, ZO-1, Occludin, and ABCG2 proteins and the increased level of inflammatory factors in the intestinal tissues of these mice.

CONCLUSION

The HUA mouse model showed intestinal barrier damage. NaB protected the intestinal barrier of HUA mice and reduced the serum UA level.

Control of Redox Homeostasis by Short-Chain Fatty Acids: Implications for the Prevention and Treatment of Breast Cancer

Breast cancer is the leading cause of death among women worldwide, and certain subtypes are highly aggressive and drug resistant. As oxidative stress is linked to the onset and progression of cancer, new alternative therapies, based on plant-derived compounds that activate signaling pathways involved in the maintenance of cellular redox homeostasis, have received increasing interest. Among the bioactive dietary compounds considered for cancer prevention and treatment are flavonoids, such as quercetin, carotenoids, such as lycopene, polyphenols, such as resveratrol and stilbenes, and isothiocyanates, such as sulforaphane. In healthy cells, these bioactive phytochemicals exhibit antioxidant, anti-apoptotic and anti-inflammatory properties through intracellular signaling pathways and epigenetic regulation. Short-chain fatty acids (SCFAs), produced by intestinal microbiota and obtained from the diet, also exhibit anti-inflammatory and anti-proliferative properties related to their redox signaling activity—and are thus key for cell homeostasis. There is evidence supporting an antioxidant role for SCFAs, mainly butyrate, as modulators of Nrf2-Keap1 signaling involving the inhibition of histone deacetylases (HDACs) and/or Nrf2 nuclear translocation. Incorporation of SCFAs in nutritional and pharmacological interventions changes the composition of the the intestinal microbiota, which has been shown to be relevant for cancer prevention and treatment. In this review, we focused on the antioxidant properties of SCFAs and their impact on cancer development and treatment, with special emphasis on breast cancer.

Fatty acids as histone deacetylase inhibitors: old biochemistry tales in a new life sciences town

Histone acetylation is a key epigenetic event. Although the keywords fatty acids, histones, and histone acetylation have a long history in biochemistry, these topics continue to attract much attention among researchers. The acetylation of histones is controlled by the activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). An imbalance in the activities of HATs and HDACs is common in a range of human cancers. Histone deacetylase inhibitors (HDACi) can restore dysregulated histone acetylation profiles in cancer cells and have been identified as promising anti-cancer therapeutics. Short-chain fatty acids mediate anti-cancer effects by inhibiting the activity of HDACs. Recent studies have identified odd-chain fatty acids as novel HDACi. This review summarizes recent findings regarding fatty acids as HDACi in cancer therapy. Teaser: Inhibition of histone deacetylase (HDAC) activity by fatty acids.

Sodium Propionate Contributes to Tumor Cell Growth Inhibition through PPAR-γ Signaling

New therapeutic approaches are needed to improve the outcome of patients with glioblastoma (GBM). Propionate, a short-chain fatty acid (SCFA), has a potent antiproliferative effect on various tumor cell types. Peroxisome proliferator-activated receptor (PPAR) ligands possess anticancer properties. We aimed to investigate the PPAR-γ/SCFAs interaction in in vitro and in vivo models of GBM. The U87 cell line was used in the in vitro study and was treated with sodium propionate (SP). U87 cells were silenced by using PPAR-γ siRNA or Ctr siRNA. In the in vivo study, BALB/c nude mice were inoculated in the right flank with 3 × 10⁶ U-87 cells. SP (doses of 30 and 100 mg/kg) and GW9662 (1 mg/kg) were administered. In vitro exposure of GBM to SP resulted in prominent apoptosis activation while the autophagy pathway was promoted by SP treatments by influencing autophagy-related proteins. Knockdown of PPAR-γ sensitized GBM cells and blocked the SP effect. In vivo, SP was able to decrease tumor growth and to resolve GBM tissue features. SP promoted apoptosis and autophagy pathways and tumor cell proliferation leading to cell cycle arrest through a PPAR-γ-dependent mechanism suggesting that the PPAR-γ/SCFAs axis could be targeted for the management of GBM.

Lacticaseibacillus rhamnosus Probio-M9-Driven Mouse Mammary Tumor-Inhibitory Effect Is Accompanied by Modulation of Host Gut Microbiota, Immunity, and Serum Metabolome

Gut microbiome may influence tumor growth and cancer treatment efficacy, so it is a potential target for tumor prevention/treatment. This pilot study investigated the preventive and therapeutic effects of a probiotic strain, Lacticaseibacillus rhamnosus Probio-M9 (Probio-M9), against murine mammary cancer. Thirty-six female mice were randomly divided into three groups (n = 12 per group): control (without tumor transplantation), model (tumor transplantation; no probiotic administration), and probiotic (30-day oral gavage of probiotic, started seven days before tumor transplantation). Changes in tumor size were recorded, and blood, tumor tissue, and stool samples were collected at the end of the trial for analyses. Comparing with the model group, the probiotic group had a significantly smaller tumor volume (p < 0.05), a higher fecal microbiota Shannon diversity index, with significant modifications in the gut microbiota structure (p < 0.05), characterized by more Alistipes sp._2, Porphyromonadaceae bacterium_7, and Bacteroidales bacterium 55_9 (p < 0.05). Additionally, Probio-M9 administration elevated the serum IFN-γ, IL-9, IL-13, and IL-27 levels and several metabolites (e.g., pyridoxal, nicotinic acid, 3-hydroxybutyric acid, glutamine; p < 0.05), while reducing IL-5 (p < 0.05). These changes might be associated with the protective effect of Probio-M9 against mammary tumor growth. Thus, probiotic administration could harness host gut microbiome in anti-cancer responses.

Exploring the mechanism of Qinbaiqingfei-concentrate pills in the treatment of Mycoplasma pneumoniae pneumonia from the perspective of intestinal microbiota and mucosal immunity

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine categorizes Mycoplasma pneumoniae pneumonia as "lung heat", and treatment with heat clear and detoxify. Traditional Chinese medicine believes that the lungs and intestines come from the same source, and the intestine is related to pneumonia. This is the same as the gut-lung axis theory. Qinbaiqingfei concentrate pills (QBs) were modified based on Cough San in the ancient medical book Medical Awareness. It clears lung heat, moisturizes the lungs and dredges collaterals, and has a good ability to treat Mycoplasma pneumoniae.

AIM OF THE STUDY

A rat model of Mycoplasma pneumoniae was established. From the aspect of intestinal flora and mucosal immunity, the potential mechanism of the QBs was researched.

MATERIALS AND METHODS

First, the content of Mycoplasma pneumoniae in lung tissue and the levels of the inflammatory factors IL-4, IL-10, TNF-α and INF-γ were detected. To determine the expression of NF-kB related proteins in lung tissue, which can understand the ability in treating disease. Next, metagenomic sequencing was performed to detect changes in short-chain fatty acids, proving the ability of the drug to regulate intestinal microecology. Finally, HDAC, LPS, SIgA, etc. were detected to facilitate the correlation of the overall experimental indicators.

RESULTS

QBs reduces the levels of IL-4, IL-10, TNF-α and INF-γ in the serum by inhibiting the expression of MyD88, IKKα, IκBα, and NF-κB p65 in lung tissue. In addition, QBs restores the ratio of gram-negative bacteria to gram-positive bacteria in the intestine, restores the secretion of acetic acid, propionic acid, butyric acid, isobutyric acid and isovaleric acid, and promotes the secretion of NF-κB p65 and SIgA by HDAC1/3. The result is that the lung tissue is repaired and the proliferation of Mycoplasma pneumoniae is inhibited.

CONCLUSIONS

From the "gut-lung axis", a new research perspective was discovered. QBs intervened in the intestines and lungs to treat Mycoplasma pneumoniae.

Functions of Gut Microbiota Metabolites, Current Status and Future Perspectives

Gut microbiota, a collection of microorganisms that live within gastrointestinal tract, provides crucial signaling metabolites for the physiological of hosts. In healthy state, gut microbiota metabolites are helpful for maintaining the basic functions of hosts, whereas disturbed production of these metabolites can lead to numerous diseases such as metabolic diseases, cardiovascular diseases, gastrointestinal diseases, neurodegenerative diseases, and cancer. Although there are many reviews about the specific mechanisms of gut microbiota metabolites on specific diseases, there is no comprehensive summarization of the functions of these metabolites. In this Opinion, we discuss the knowledge of gut microbiota metabolites including the types of gut microbiota metabolites and their ways acting on targets. In addition, we summarize their physiological and pathologic functions in health and diseases, such as shaping the composition of gut microbiota and acting as nutrition. This paper can be helpful for understanding the roles of gut microbiota metabolites and thus provide guidance for developing suitable therapeutic strategies to combat microbial-driven diseases and improve health.

Bile Duct Ligation Impairs Function and Expression of Mrp1 at Rat Blood–Retinal Barrier via Bilirubin-Induced P38 MAPK Pathway Activations

Liver injury is often associated with hepatic retinopathy, resulting from accumulation of retinal toxins due to blood–retinal barrier (BRB) dysfunction. Retinal pigment epithelium highly expresses MRP1/Mrp1. We aimed to investigate whether liver injury affects the function and expression of retinal Mrp1 using bile duct ligation (BDL) rats. Retinal distributions of fluorescein and 2,4-dinitrophenyl-S-glutathione were used for assessing Mrp1 function. BDL significantly increased distributions of the two substrates and bilirubin, downregulated Mrp1 protein, and upregulated phosphorylation of p38 and MK2 in the retina. BDL neither affected the retinal distribution of FITC-dextran nor expressions of ZO-1 and claudin-5, demonstrating intact BRB integrity. In ARPE-19 cells, BDL rat serum or bilirubin decreased MRP1 expression and enhanced p38 and MK2 phosphorylation. Both inhibiting and silencing p38 significantly reversed the bilirubin- and anisomycin-induced decreases in MRP1 protein. Apparent permeability coefficients of fluorescein in the A-to-B direction (P_{app, A-to-B}) across the ARPE-19 monolayer were greater than P_{app, B-to-A}. MK571 or bilirubin significantly decreased P_{app, A-to-B} of fluorescein. Bilirubin treatment significantly downregulated Mrp1 function and expression without affecting integrity of BRB and increased bilirubin levels and phosphorylation of p38 and MK2 in rat retina. In conclusion, BDL downregulates the expression and function of retina Mrp1 by activating the p38 MAPK pathway due to increased bilirubin levels.

The Role of the Intestine in the Development of Hyperuricemia

Gout is a common inflammatory arthritis caused by the deposition of sodium urate crystals in the joints. Hyperuricemia is the fundamental factor of gout. The onset of hyperuricemia is related to purine metabolism disorders or uric acid excretion disorders. Current studies have shown that the intestine is an important potential organ for the excretion of uric acid outside the kidneys. The excretion of uric acid of gut is mainly achieved through the action of uric acid transporters and the catabolism of intestinal flora, which plays an important role in the body’s uric acid balance. Here we reviewed the effects of intestinal uric acid transporters and intestinal flora on uric acid excretion, and provide new ideas for the treatment of hyperuricemia and gout.

Regulation of Drug Transport Proteins-From Mechanisms to Clinical Impact: A White Paper on Behalf of the International Transporter Consortium

Membrane transport proteins are involved in the absorption, disposition, efficacy, and/or toxicity of many drugs. Numerous mechanisms (e.g., nuclear receptors, epigenetic gene regulation, microRNAs, alternative splicing, post‐translational modifications, and trafficking) regulate transport protein levels, localization, and function. Various factors associated with disease, medications, and dietary constituents, for example, may alter the regulation and activity of transport proteins in the intestine, liver, kidneys, brain, lungs, placenta, and other important sites, such as tumor tissue. This white paper reviews key mechanisms and regulatory factors that alter the function of clinically relevant transport proteins involved in drug disposition. Current considerations with in vitro and in vivo models that are used to investigate transporter regulation are discussed, including strengths, limitations, and the inherent challenges in predicting the impact of changes due to regulation of one transporter on compensatory pathways and overall drug disposition. In addition, translation and scaling of in vitro observations to in vivo outcomes are considered. The importance of incorporating altered transporter regulation in modeling and simulation approaches to predict the clinical impact on drug disposition is also discussed. Regulation of transporters is highly complex and, therefore, identification of knowledge gaps will aid in directing future research to expand our understanding of clinically relevant molecular mechanisms of transporter regulation. This information is critical to the development of tools and approaches to improve therapeutic outcomes by predicting more accurately the impact of regulation‐mediated changes in transporter function on drug disposition and response.

Lactobacillus Suppresses Tumorigenesis of Oropharyngeal Cancer via Enhancing Anti-Tumor Immune Response

Deficiency in T cell-mediated adaptive immunity, such as low CD8⁺ T cell infiltration, inhibits the immune surveillance, promotes malignant transformation, and facilitates tumor growth. Microbiota dysbiosis diminishes the immune system and contributes to the occurrence of cancer. However, the impact of oral dysbiosis on the occurrence and molecular mechanisms of oropharyngeal cancer (OPC) remains largely unknown. In the current study, we used 4-nitroquinoline-1-oxide (4NQO) to mimic tobacco-related carcinogenesis to generate a murine OPC model and determine the role of microbiota changes in OPC tumorigenesis. Our results showed that the oral flora composition of mice was deregulated during the tumorigenesis of OPC. The abundance of Streptococcus, Veillonella, Muribacter, Rodentibacter, and Gemella was increased, whereas the dominant genus Lactobacillus was gradually decreased with disease progression. We further demonstrated that infiltration of CD8⁺ T lymphocytes was markedly reduced due to the reduction of Lactobacillus. Supplementation of Lactobacillus increased the infiltration of CD8⁺ T cells, promoted the expression of IFN-γ and granzyme B, and lessened the OPC progression. Analyzing the metabolites of the Lactobacillus, we demonstrated that Lactobacillus enhanced the anti-tumor immune response by producing acetate in OPC development. Administration of acetate to mice could increase the expression of IFN-γ and IFN-γ-inducible chemokines in tumor tissues by activating GPR43 to promote the infiltration of CD8⁺ T lymphocytes and substantially delay the development of OPC. Together, our data suggest that dysbiosis of oral microbiota promotes the tumorigenesis of OPC through downregulation of cytotoxic T lymphocytes. Lactobacillus and its metabolite acetate improve the tumor microenvironment, which could be applied in the treatment of OPC.

Regulation of Butyrate-Induced Resistance through AMPK Signaling Pathway in Human Colon Cancer Cells

Butyrates inhibit cell growth in colon cancer cells by inhibiting histone deacetylases. However, chronic exposure to butyrates induces butyrate resistance in colon cancer cells. The mechanism underlying the acquisition of resistance is not yet fully understood. Here, butyrate-resistant (BR) colon cancer cells were developed in HCT116, HT29, and SW480 human colon cancer cells and were confirmed by the increase in the inhibitory concentrations of cell growth by 50% (IC₅₀) compared to their respective parental (PT) cells. Chronic exposure to butyrate induced autophagy via higher expression of Beclin-1 and LC3B-II. The AMP-activated protein kinase (AMPK) was downregulated along with the activation of Akt and mammalian target of rapamycin (mTOR) and decrease in acetyl-CoA carboxylase (ACC) in BR colon cancer cells compared to those in their respective PT cells. Activation of AMPK by AICAR treatment in BR colon cancer cells suppressed cell proliferation by inhibiting Akt and mTOR and activating ACC. Taken together, chronic exposure to butyrate increased butyrate resistance in human colon cancer by inducing protective autophagy through the downregulation of AMPK/ACC and activation of Akt/mTOR signaling. Activation of AMPK restored sensitivity to butyrate by the inhibition of Akt/mTOR, suggesting that AMPK could be a therapeutic target for BR colon cancers.

A Non-Nutritive Feeding Intervention Alters the Expression of Efflux Transporters in the Gastrointestinal Tract

Intestinal interactions with nutrients, xenobiotics and endogenous hormones can influence the expression of clinically relevant membrane transporters. These changes in the gastrointestinal (GI) physiology can in turn affect the absorption of numerous drug substrates. Several studies have examined the effect of food on intestinal transporters in male and female humans and animal models. However, to our knowledge no studies have investigated the influence of a non-nutritive fibre meal on intestinal efflux transporters and key sex and GI hormones. Here, we show that a fibre meal increased the acute expression of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug-resistance-associated protein-2 (MRP2) in small intestinal segments in both male and female Wistar rats. Enzyme-linked immunosorbent assays were used for the protein quantification of efflux transporters and hormonal plasma concentration. In male rats, the fibre meal caused the plasma concentration of the GI hormone cholecystokinin (CCK) to increase by 75% and the sex hormone testosterone to decrease by 50%, whereas, in contrast, the housing food meal caused a decrease in CCK by 32% and testosterone saw an increase of 31%. No significant changes in the hormonal concentrations, however, were seen in female rats. A deeper understanding of the modulation of efflux transporters by sex, food intake and time can improve our understanding of inter- and intra-variability in the pharmacokinetics of drug substrates.

Interactions between gut microbiota and berberine, a necessary procedure to understand the mechanisms of berberine

Berberine (BBR), an isoquinoline alkaloid, has been found in many plants, such as Coptis chinensis Franch and Phellodendron chinense Schneid. Although BBR has a wide spectrum of pharmacological effects, its oral bioavailability is extremely low. In recent years, gut microbiota has emerged as a cynosure to understand the mechanisms of action of herbal compounds. Numerous studies have demonstrated that due to its low bioavailability, BBR can interact with the gut microbiota, thereby exhibiting altered pharmacological effects. However, no systematic and comprehensive review has summarized these interactions and their corresponding influences on pharmacological effects. Here, we describe the direct interactive relationships between BBR and gut microbiota, including regulation of gut microbiota composition and metabolism by BBR and metabolization of BBR by gut microbiota. In addition, the complex interactions between gut microbiota and BBR as well as the side effects and personalized use of BBR are discussed. Furthermore, we provide our viewpoint on future research directions regarding BBR and gut microbiota. This review not only helps to explain the mechanisms underlying BBR activity but also provides support for the rational use of BBR in clinical practice.

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Low bioavailability enables interactions between berberine and the gut microbiota.

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Berberine can shape the composition and metabolism of the gut microbiota.

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Gut microbiota can metabolize and transform berberine.

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Personalized use of berberine can reduce the occurrence of side effects.

Structure-Based Discovery of Pyrimidine Aminobenzene Derivatives as Potent Oral Reversal Agents against P-gp- and BCRP-Mediated Multidrug Resistance

Overexpression of ATP binding cassette (ABC) transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), is an important factor leading to multidrug resistance (MDR) in cancer treatments. Three subclasses of dual inhibitors of P-gp and BCRP were designed based on the active moieties of BCRP inhibitors, tyrosine kinase inhibitors, and P-gp inhibitors, of which compound 21 possessed low cytotoxicity, high reversal potency, and good lipid distribution coefficient. 21 also increased the accumulation of Adriamycin (ADM) and Mitoxantrone (MX), blocked Rh123 efflux, and made no change in the protein expression of P-gp and BCRP. Importantly, coadministration of 21 can significantly improve the oral bioavailability of paclitaxel (PTX). It was also demonstrated that 21 significantly inhibited the growth of K562/A02 xenograft tumors by increasing the sensitivity of ADM in vivo. In summary, 21 has the potential to overcome MDR caused by P-gp and BCRP and to improve the oral bioavailability of PTX.

Changes of intestinal microflora of breast cancer in premenopausal women

Breast cancer is one of the most common malignant tumors in women. More than half of breast cancer patients are not menopausal at the time of diagnosis. The occurrence and development of premenopausal breast cancer are affected by many factors. Intestinal flora, especially SCFA-producing bacteria, participates in the development of various tumors, and there is a lack of in-depth research in premenopausal breast cancer patients. We used 16S rRNA gene sequencing, targeted metabolomics, and cell culture methods to analyze the changes in the intestinal flora and metabolites of premenopausal breast cancer patients. In addition, we treated breast cancer cells with significantly altered propionate and butyrate in vitro to examine their effects on cell activity. This study followed STROBE guidelines. We found that compared with healthy premenopausal women, the composition and symbiosis of intestinal flora in patients with premenopausal breast cancer changed significantly. The abundance of short-chain fatty acid (SCFA)-producing bacteria was significantly reduced, and the key SCFA-producing enzymes were also significantly reduced. Pediococcus and Desulfovibrio could distinguish premenopausal breast cancer patients from normal premenopausal women. The related propionate and butyrate had a certain ability to inhibit breast cancer cell viability in vitro. As SCFA-producing bacteria, Pediococcus and Desulfovibrio showed potential reference value for the diagnosis of premenopausal breast cancer. The ability of propionate and butyrate to inhibit breast cancer cell lines in vitro suggests that the relevant SCFA receptor may be a new target for the treatment of premenopausal breast cancer.