Keto microbiota: A powerful contributor to host disease recovery.

Gut microbiota (GM) is a key contributor to host metabolism and physiology. Data generated on comparing diseased and healthy subjects have reported changes in the GM profile between both health states, suggesting certain bacterial composition could be involved in pathogenesis. Moreover, studies reported that reshaping of GM could contribute actively to disease recovery. Interestingly, ketogenic diets (KD) have emerged recently as new economic dietotherapeutic strategy to combat a myriad of diseases (refractory epilepsy, obesity, cancer, neurodegenerative diseases…). KD, understood in a broad sense, refers to whatever dietetic approximation, which causes physiological ketosis. Therefore, high fat-low carbs diets, fasting periods or caloric restriction constitute different strategies to produce an increase of main ketones bodies, acetoacetate and ß-hydroxybutyrate, in blood. Involved biological mechanisms in ketotherapeutic effects are still to be unravelled. However, it has been pointed out that GM remodelling by KD, from now on "keto microbiota", may play a crucial role in patient response to KD treatment. In fact, germ-free animals were resistant to ketotherapeutic effects; reinforcing keto microbiota may be a powerful contributor to host disease recovery. In this review, we will comment the influence of gut microbiota on host, as well as, therapeutic potential of ketogenic diets and keto microbiota to restore health status. Current progress and limitations will be argued too. In spite of few studies have defined applicability and mechanisms of KD, in the light of results, keto microbiota might be a new useful therapeutic agent.

Relationship of Zonulin with Serum PCSK9 Levels after a High Fat Load in a Population of Obese Subjects.

Despite the fact that circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) remain unchanged after fat load in healthy lean individuals, PCSK9 has been suggested to have a role in postprandial lipemia regulation in obese individuals. On the other hand, intestinal permeability and endotoxemia have been observed to increase more in obese individuals than in non-obese individuals after a lipid load. This study aimed to analyze the relationship between PCSK9, intestinal permeability, and endotoxemia after a high fat load in obese individuals. We included 39 individuals with morbid obesity. Serum PCSK9 levels, intestinal permeability marker (zonulin), endotoxemia markers (LPS and LBP), and lipid parameters were measured before and after 3 h of fat load. A significant rise in triglycerides, apolipoprotein A1, zonulin, LPS, and LBP, and a significant decline in PCSK9, were observed after a lipid load. Linear regression analysis showed that low-density lipoprotein cholesterol (LDL-C) was independently related to PCSK9 at baseline, whereas both zonulin and LDL-C were independently related to PCSK9 levels after fat load. A relationship between zonulin and PCSK9 levels after fat load in individuals with morbid obesity may exist.

Association between variation of circulating 25-OH vitamin D and methylation of secreted frizzled-related protein 2 in colorectal cancer.

BACKGROUNDS: Colorectal cancer (CRC) results from the accumulation of epigenetic and genetic changes in colon cells during neoplasic transformation, which the activation of Wingless (Wnt) signaling pathway is a common mechanism for CRC initiation. The Wnt pathway is mainly regulated by Wnt antagonists, as secreted frizzled-related protein (SFRP) family. Indeed, SFRP2 is proposed as a noninvasive biomarker for CRC diagnosis. Vitamin D also antagonizes Wnt signaling in colon cancers cells. Several studies showed that vitamin D was able to alter DNA methylation, although this mechanism is not yet clear. Therefore, the aim of this study was to find an association between circulating 25-OH vitamin D (30th percentile of vitamin D) and the SFRP2 methylation. METHODS: A total of 67 CRC patients were included in the study. These patients were subdivided into two groups based on their 30th percentile vitamin D (20 patients were below, and 47 participants were above the 30th percentile of vitamin D). We investigated the SFRP2 methylation in peripheral blood mononuclear cells (PBMCs), visceral adipose tissue (VAT), CRC tumor tissue, and adjacent tumor-free area. We also determined the relationship between SFRP2 methylation and methylation of carcinogenic and adipogenic genes. Finally, we tested the effect of vitamin D on the SFRP2 methylation in human colorectal carcinoma cell lines 116 (HCT116) and studied the association of neoadjuvant therapy under the 30th percentile vitamin D with SFRP2 promoter methylation. RESULTS: SFRP2 methylation in tumor area was decreased in patients who had higher levels of vitamin D. SFRP2 promoter methylation was positively correlated in tumor area with insulin and homeostasis model assessment of insulin resistance (HOMA-IR) but negatively correlated with HDL-c. SFRP2 methylation was also correlated with T cell lymphoma invasion and metastasis 1 (TIAM1) methylation in tumor area and CCAAT/enhancer-binding protein alpha (C/EBPα) in VAT. Treatment with vitamin D did not affect SFRP2 methylation in HCT116 cell line. Finally, neoadjuvant treatment was correlated with higher circulating 25-OH vitamin D and SFRP2 methylation under linear regression model. CONCLUSION: Our results showed that higher circulating vitamin D is associated with low SFRP2 promoter methylation. Therefore, our results could suggest that vitamin D may have an epigenetic effect on DNA methylation. Finally, higher vitamin D could contribute to an improvement response to neoadjuvant treatment.

The Expression/Methylation Profile of Adipogenic and Inflammatory Transcription Factors in Adipose Tissue Are Linked to Obesity-Related Colorectal Cancer.

Obesity is well accepted as crucial risk factor that plays a critical role in the initiation and progression of colorectal cancer (CRC). More specifically, visceral adipose tissue (VAT) in people with obesity could produce chronic inflammation and an altered profile expression of key transcription factors that promote a favorable microenvironment to colorectal carcinogenesis. For this, the aim of this study was to explore the relationship between adipogenic and inflammatory transcription factors in VAT from nonobese, obese, and/or CRC patients. To test this idea, we studied the expression and methylation of CCAAT-enhancer binding protein type alpha (C/EBP-α), peroxisome proliferator-activated receptor gamma (PPAR-γ), peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) in VAT from non-obese control, non-obese CRC subjects, overweight/obese control, and overweight/obese CRC patients and their correlation with anthropometric and biochemical variables. We found decreased expression of C/EBP-α in overweight/obese CRC patients in comparison with overweight/obese control subjects. PGC-1α and NF-κB were overexpressed in CRC patients independently of the BMI. NF-κB promoter was hypomethylated in overweight/obese CRC patients when compared to overweight/obese control individuals. In addition, multiple significant correlations between expression, methylation, and biochemical parameters were found. Finally, linear regression analysis showed that the expression of C/EBP-α and NF-κB and that NF-κB methylation were associated with CRC and able to explain up to 55% of CRC variability. Our results suggest that visceral adipose tissue may be a key factor in tumor development and inflammatory state. We propose C/EBP-α, PGC-1α and NF-κB to be interesting candidates as potential biomarkers in adipose tissue for CRC patients.

Transcriptional Analysis of FOXO1, C/EBP-α and PPAR-γ2 Genes and Their Association with Obesity-Related Insulin Resistance.

BACKGROUND: Obesity is associated with several comorbid disorders, ranging from cardiovascular diseases to insulin resistance. In this context, visceral adipose tissue (VAT) seems to have a close connection with insulin resistance. In our study, we hypothesized that the expression profile of key adipogenic genes, such as proliferator-activated receptor γ type 2 (PPAR-γ2), CCAAT/enhancer-binding protein type α (C/EBP-α), and forkhead box protein class O type 1 (FOXO1) in VAT should shed light on their association with obesity-related insulin resistance. METHODS: To test this idea, we studied the expression profile of C/EBP-α, FOXO1 and PPAR-γ2 in VAT from non-obese individuals, and low insulin (LIR-MO) and high insulin morbidly obese (HIR-MO) subjects, through a combination of RT-qPCR, co-immunoprecipitation, ELISA, Western blot analysis and EMSA assays. RESULTS: Our results show that C/EBP-α and PPAR-γ2 were down-expressed in HIR-MO individuals, while FOXO1 was overexpressed. In addition, the PPAR-γ2-RXR-α heterodimer showed weak activity and bound weakly to the putative IGFBP-2-PPRE promoter sequence in VAT from HIR-MO subjects when compared with LIR-MO individuals. CONCLUSIONS: These results show that PPAR-γ2, C/EBP-α, FOXO1 and IGFBP-2 have a close relationship with insulin resistance in VAT of morbidly obese individuals.

Novel SFRP2 DNA Methylation Profile Following Neoadjuvant Therapy in Colorectal Cancer Patients with Different Grades of BMI.

The relationship between body weight and different cancers is now well-recognized and among such cancers, colorectal cancer (CRC) is reported most frequently. Our group recently published findings, through an epigenome-wide association study, suggesting that body mass index (BMI) could act as a relevant risk factor in the CRC. In addition, aberrant SFRP2 methylation is one of the major mechanisms for Wnt signaling activation in CRC. Conversely, neoadjuvant chemo-radiotherapy appears to alter the rectal cancer epigenome. This study was aimed to evaluate the effect of obesity, measured by BMI, on the methylation of SFRP2 in tumor samples of patients with CRC. Non-treated CRC patients and CRC patients treated with pre-operative neoadjuvant therapy from 2011 to 2013 were included and classified by BMI < 25.0 kg/m2 and BMI > 25.0 kg/m2. SFRP2 DNA methylation in tumor samples was measured by pyrosequencing. Our findings suggest a possible interaction between SFRP2 methylation levels and BMI in CRC tumor samples. The correlation of SFRP2 hypomethylation with an elevated BMI was stronger within the non-treated CRC patient group than within the treated CRC patient group. We have successfully demonstrated that the beneficial association of tumor SFRP2 hypomethylation is dependent on patient BMI in non-treated CRC, suggesting a possible tumor suppressor role for SFRP2 in overweight and obese patients. Additional studies of clinical pathologies would be necessary to strengthen these preliminary results.

Gut Microbiota Composition Is Associated With the Global DNA Methylation Pattern in Obesity.

Objective: Obesity and obesity-related metabolic diseases are characterized by gut microbiota and epigenetic alterations. Recent insight has suggested the existence of a crosstalk between the gut microbiome and the epigenome. However, the possible link between alterations in gut microbiome composition and epigenetic marks in obesity has been not explored yet. The aim of this work is to establish a link between the gut microbiota and the global DNA methylation profile in a group of obese subjects and to report potential candidate genes that could be epigenetically regulated by gut microbiota in adipose tissue. Methods: Gut microbiota composition was analyzed in DNA stool samples from 45 obese subjects by 16S ribosomal RNA (rRNA) gene sequencing. Twenty patients were selected based on their Bacteroidetes-to-Firmicutes ratio (BFR): HighBFR group (BFR > 2.5, n = 10) and LowBFR group (BFR < 1.2, n = 10). Genome-wide analysis of DNA methylation pattern in both whole blood and visceral adipose tissue of these selected patients was performed with an Infinium EPIC BeadChip array-based platform. Gene expression analysis of candidate genes was done in adipose tissue by real-time quantitative PCR. Results: Genome-wide analysis of DNA methylation revealed a completely different DNA methylome pattern in both blood and adipose tissue in the low BFR group vs. the high BFR group. Two hundred fifty-eight genes were differentially methylated in both blood and adipose tissue, of which several potential candidates were selected for gene expression analysis. We found that in adipose tissue, both HDAC7 and IGF2BP2 were hypomethylated and overexpressed in the low BFR group compared with the high BFR group. ß values of both genes significantly correlated with the BFR ratio and the relative abundance of Bacteroidetes and/or Firmicutes. Conclusions: In this study, we demonstrate that the DNA methylation status is associated with gut microbiota composition in obese subjects and that the expression levels of candidate genes implicated in glucose and energy homeostasis (e.g., HDAC7 and IGF2BP2) could be epigenetically regulated by gut bacterial populations in adipose tissue.