Polyphenolic Compounds: Orchestrating Intestinal Microbiota Harmony during Aging.

In the aging process, physiological decline occurs, posing a substantial threat to the physical and mental well-being of the elderly and contributing to the onset of age-related diseases. While traditional perspectives considered the maintenance of life as influenced by a myriad of factors, including environmental, genetic, epigenetic, and lifestyle elements such as exercise and diet, the pivotal role of symbiotic microorganisms had been understated. Presently, it is acknowledged that the intestinal microbiota plays a profound role in overall health by signaling to both the central and peripheral nervous systems, as well as other distant organs. Disruption in this bidirectional communication between bacteria and the host results in dysbiosis, fostering the development of various diseases, including neurological disorders, cardiovascular diseases, and cancer. This review aims to delve into the intricate biological mechanisms underpinning dysbiosis associated with aging and the clinical ramifications of such dysregulation. Furthermore, we aspire to explore bioactive compounds endowed with functional properties capable of modulating and restoring balance in this aging-related dysbiotic process through epigenetics alterations.

Metabolic Insights into Caffeine's Anti-Adipogenic Effects: An Exploration through Intestinal Microbiota Modulation in Obesity.

Obesity, a chronic condition marked by the excessive accumulation of adipose tissue, not only affects individual well-being but also significantly inflates healthcare costs. The physiological excess of fat manifests as triglyceride (TG) deposition within adipose tissue, with white adipose tissue (WAT) expansion via adipocyte hyperplasia being a key adipogenesis mechanism. As efforts intensify to address this global health crisis, understanding the complex interplay of contributing factors becomes critical for effective public health interventions and improved patient outcomes. In this context, gut microbiota-derived metabolites play an important role in orchestrating obesity modulation. Microbial lipopolysaccharides (LPS), secondary bile acids (BA), short-chain fatty acids (SCFAs), and trimethylamine (TMA) are the main intestinal metabolites in dyslipidemic states. Emerging evidence highlights the microbiota's substantial role in influencing host metabolism and subsequent health outcomes, presenting new avenues for therapeutic strategies, including polyphenol-based manipulations of these microbial populations. Among various agents, caffeine emerges as a potent modulator of metabolic pathways, exhibiting anti-inflammatory, antioxidant, and obesity-mitigating properties. Notably, caffeine's anti-adipogenic potential, attributed to the downregulation of key adipogenesis regulators, has been established. Recent findings further indicate that caffeine's influence on obesity may be mediated through alterations in the gut microbiota and its metabolic byproducts. Therefore, the present review summarizes the anti-adipogenic effect of caffeine in modulating obesity through the intestinal microbiota and its metabolites.

The Effects of Green Tea Catechins in Hematological Malignancies.

Green tea catechins are bioactive polyphenol compounds which have attracted significant attention for their diverse biological activities and potential health benefits. Notably, epigallocatechin-3-gallate (EGCG) has emerged as a potent apoptosis inducer through mechanisms involving caspase activation, modulation of Bcl-2 family proteins, disruption of survival signaling pathways and by regulating the redox balance, inducing oxidative stress. Furthermore, emerging evidence suggests that green tea catechins can modulate epigenetic alterations, including DNA methylation and histone modifications. In addition to their apoptotic actions, ROS signaling effects and reversal of epigenetic alterations, green tea catechins have shown promising results in promoting the differentiation of leukemia cells. This review highlights the comprehensive actions of green tea catechins and provides valuable insights from clinical trials investigating the therapeutic potential of green tea catechins in leukemia treatment. Understanding these multifaceted mechanisms and the outcomes of clinical trials may pave the way for the development of innovative strategies and the integration of green tea catechins into clinical practice for improving leukemia patient outcomes.

Polyphenolic Flavonoid Compound Quercetin Effects in the Treatment of Acute Myeloid Leukemia and Myelodysplastic Syndromes.

Flavonoids are ubiquitous groups of polyphenolic compounds present in most natural products and plants. These substances have been shown to have promising chemopreventive and chemotherapeutic properties with multiple target interactions and multiple pathway regulations against various human cancers. Polyphenolic flavonoid compounds can block the initiation or reverse the promotion stage of multistep carcinogenesis. Quercetin is one of the most abundant flavonoids found in fruits and vegetables and has been shown to have multiple properties capable of reducing cell growth in cancer cells. Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) therapy remains a challenge for hematologists worldwide, and the outcomes for patients with both disorders continue to be poor. This scenario indicates the increasing demand for innovative drugs and rational combinative therapies. Herein, we discuss the multitarget effects of the flavonoid quercetin, a naturally occurring flavonol, on AML and MDS.

Exosomes in the serum of Acute Myeloid Leukemia patients induce dendritic cell tolerance: Implications for immunotherapy.

Exosomes may represent an interesting antigenic pulse for new forms of anti-tumor immunotherapy. We evaluated exosomes from serum of patients with acute myeloid leukemia (AML) as an antigenic source for dendritic cells (DC) and the effects upon antitumor cytotoxicity, assessed by the percentage of specific lysis of K562 leukemic cells in co-cultures. Surprisingly, incubation of exosomes with DCs decreased lysis of K562, which may correspond to a mechanism of tumor evasion in vivo. However, when immature DCs were pulsed with exosomes purified from K562 culture supernatants, the lysis of target cells was notably enhanced, associated with a substantial increase in the expression of the maturation marker CD83. Thus, the development of vaccines using patients' exosomes would probably add no benefits to the treatment of AML; alternately, exosomes from cultured cells may represent an effective way for maturing DCs into a cytotoxic phenotype, without the immunosuppression observed with patients' exosomes.

Up-regulation of SPINT2/HAI-2 by Azacytidine in bone marrow mesenchymal stromal cells affects leukemic stem cell survival and adhesion.

The role of tumour microenvironment in neoplasm initiation and malignant evolution has been increasingly recognized. However, the bone marrow mesenchymal stromal cell (BMMSC) contribution to disease progression remains poorly explored. We previously reported that the expression of serine protease inhibitor kunitz-type2 (SPINT2/HAI-2), an inhibitor of hepatocyte growth factor (HGF) activation, is significantly lower in BMMSC from myelodysplastic syndromes (MDS) patients compared to healthy donors (HD). Thus, to investigate whether this loss of expression was due to SPINT2/HAI-2 methylation, BMMSC from MDS and de novo acute myeloid leukaemia (de novo AML) patients were treated with 5-Azacitidine (Aza), a DNA methyltransferase inhibitor. In MDS- and de novo AML-BMMSC, Aza treatment resulted in a pronounced SPINT2/HAI-2 levels up-regulation. Moreover, Aza treatment of HD-BMMSC did not improve SPINT2/HAI-2 levels. To understand the role of SPINT2/HAI-2 down-regulation in BMMSC physiology, SPINT2/HAI-2 expression was inhibited by lentivirus. SPINT2 underexpression resulted in an increased production of HGF by HS-5 stromal cells and improved survival of CD34+ de novo AML cells. We also observed an increased adhesion of de novo AML hematopoietic cells to SPINT2/HAI-2 silenced cells. Interestingly, BMMSC isolated from MDS and de novo AML patients had increased expression of the integrins CD49b, CD49d, and CD49e. Thus, SPINT2/HAI-2 may contribute to functional and morphological abnormalities of the microenvironment niche and to stem/progenitor cancer cell progression. Hence, down-regulation in SPINT2/HAI-2 gene expression, due to methylation in MDS-BMMSC and de novo AML-BMMSC, provides novel insights into the pathogenic role of the leukemic bone marrow microenvironment.

Small Particles, Big Effects: The Interplay Between Exosomes and Dendritic Cells in Antitumor Immunity and Immunotherapy.

Dendritic cells play a fundamental role in the antitumor immunity cycle, and the loss of their antigen-presenting function is a recognized mechanism of tumor evasion. We have recently demonstrated the effect of exosomes extracted from serum of patients with acute myeloid leukemia as important inducers of dendritic cell immunotolerance, and several other works have recently demonstrated the effects of these nanoparticles on immunity to other tumor types as well. The aim of this review was to highlight the recent findings on the effects of tumor exosomes on dendritic cell functions, the mechanisms by which they can lead to tumor evasion, and their manipulation as a possible strategy in cancer treatment.

The polyphenol quercetin induces cell death in leukemia by targeting epigenetic regulators of pro-apoptotic genes.

BACKGROUND: In the present study, we investigated the molecular mechanisms underlying the pro-apoptotic effects of quercetin (Qu) by evaluating the effect of Qu treatment on DNA methylation and posttranslational histone modifications of genes related to the apoptosis pathway. This study was performed in vivo in two human xenograft acute myeloid leukemia (AML) models and in vitro using HL60 and U937 cell lines. RESULTS: Qu treatment almost eliminates DNMT1 and DNMT3a expression, and this regulation was in part STAT-3 dependent. The treatment also downregulated class I HDACs. Furthermore, treatment of the cell lines with the proteasome inhibitor, MG132, together with Qu prevented degradation of class I HDACs compared to cells treated with Qu alone, indicating increased proteasome degradation of class I HDACS by Qu. Qu induced demethylation of the pro-apoptotic BCL2L11, DAPK1 genes, in a dose- and time-dependent manner. Moreover, Qu (50 µmol/L) treatment of cell lines for 48 h caused accumulation of acetylated histone 3 and histone 4, resulting in three- to ten fold increases in the promoter region of DAPK1, BCL2L11, BAX, APAF1, BNIP3, and BNIP3L. In addition, Qu treatment significantly increased the mRNA levels of all these genes, when compared to cells treated with vehicle only (control cells) (*p < 0.05). CONCLUSIONS: In summary, our results showed that enhanced apoptosis, induced by Qu, might be caused in part by its DNA demethylating activity, by HDAC inhibition, and by the enrichment of H3ac and H4ac in the promoter regions of genes involved in the apoptosis pathway, leading to their transcription activation.

Effect of Helicobacter pylori Infection on GATA-5 and TFF1 Regulation, Comparison Between Pediatric and Adult Patients.

BACKGROUND: GATA factors, which constitute a family of transcription regulatory proteins, participate in gastrointestinal development. Trefoil factor 1 (TFF1) plays a crucial role in mucosal defense and healing, and evidence suggests that GATA-5 mediated its regulation. Gastric cancer is a multiple-step process triggered by Helicobacter pylori and is characterized by accumulation of molecular and epigenetic alteration. The aim of this study was to evaluate the effect of H. pylori infection on the regulation of GATA-5 and TFF1 in vitro and in vivo. RESULTS: Infected cells exhibited upregulation of GATA-5 and TFF1 after 48 h. An increase in GATA-5 and TFF1 mRNA levels was also found in mice samples after 6 and 12 months of infection, respectively. In human samples, we found an association between H. pylori infection and GATA-5 upregulation. In fact, among H. pylori-infected patients, hypermethylation was observed in 45.5% of pediatric samples, in 62.6% of chronic gastritis samples, and in 63% of gastric cancer samples. Regarding TFF1, the expression levels were similar in pediatrics and adults patients, and were independent of H. pylori infection, and the expression of these factors was downregulated in gastric cancer samples. GATA-5 promoter methylation was associated with a decrease in TFF1 mRNA levels. CONCLUSIONS: Our results suggest that the upregulation of GATA-5 and TFF1 observed in vitro and in vivo may be correlated with a protective effect of the mucosa in response to infection. The epigenetic inactivation of GATA-5 observed in human biopsies from infected patients may suggest that this alteration is an early event occurring in association with H. pylori infection.

Methylation pattern of THBS1, GATA-4, and HIC1 in pediatric and adult patients infected with Helicobacter pylori.

BACKGROUND: Helicobacter pylori infection is usually acquired in childhood and persists into adulthood if untreated. The bacterium induces a chronic inflammatory response, which is associated with epigenetic alterations in oncogenes, tumor-suppressor genes, cell-cycle regulators, and cell-adhesion molecules. AIM: The aim of this study was to analyze the effect of H. pylori infection on the methylation status of Thrombospondin-1 (THBS1), Hypermethylated in cancer 1 (HIC1) and Gata binding protein-4 (GATA-4) in gastric biopsy samples from children and adults infected or uninfected with the bacterium and in samples obtained from gastric cancer patients. METHODS: The methylation pattern was analyzed with methylation-specific PCR. RESULTS: Our results showed that H. pylori infection was associated with methylation of the promoter regions of the THBS1 and GATA-4 genes in pediatric and adult samples (p < 0.01). HIC1 showed the lowest level of methylation, which was not an early event during gastric carcinogenesis. CONCLUSIONS: The results from this study indicate that methylation of THBS1 and GATA-4 occurs in the early stages of chronic gastritis and gastric cancer in association with H. pylori infection; however, in gastric cancer samples, other mechanisms cooperate with the down-regulation of these genes. Methylation of HIC1 may not be the principal mechanism implicated in its down-regulation in gastric cancer samples.

Effect of Helicobacter pylori infection on IL-8, IL-1beta and COX-2 expression in patients with chronic gastritis and gastric cancer.

OBJECTIVE: Helicobacter pylori infection is related to gastric cancer development, and chronic inflammation is presumed to be the main cause. The aim of the present study was to evaluate the influence of H. pylori cagA, vacA, iceA, and babA genotypes on COX-2, IL-1beta, and IL-8 expression. MATERIAL AND METHODS: Of the 217 patients included in the study, 26 were uninfected, 127 had chronic gastritis and were H. pylori-positive, and 64 had gastric cancer. Bacterial genotypes were evaluated by polymerase chain reaction (PCR), and the expression values were determined by quantitative real-time PCR and immunohistochemistry. RESULTS: An association was found between the infection with cagA, vacA s1m1 strains and gastric cancer development. Regarding the 3' region of the cagA gene, we also found an association between the infection with cagA EPIYA-ABCCC strains and clinical outcome. Higher levels of IL-8, IL-1beta, and COX-2 were detected in gastric mucosa from infected patients with chronic gastritis, and they were also associated with the infection by cagA, vacA s1m1 strains. The IL-8 and IL-1beta levels decrease significantly from chronic gastritis to gastric cancer, while the relative expression remained unaltered when COX-2 expression was analyzed among patients with gastritis and cancer. CONCLUSIONS: Since inflammatory response to H. pylori infection plays an important role in cellular proliferation and gastric mucosal damage, the up-regulation of IL-1beta, IL-8, and COX-2 in patients with chronic gastritis has an important clinical implication in gastric carcinogenesis.