Lower miR-26a levels in breastmilk affect gene expression in adipose tissue of offspring.

Breastmilk miRNAs may act as epigenetic regulators of metabolism and energy homeostasis in offspring. Here, we aimed to investigate the regulatory effects of miR-26a on adipose tissue development. First, the 3T3-L1 cell model was used to identify putative target genes for miR-26a. Then, target genes were analysed in adipose tissue of offspring from dams that supplied lower levels of breastmilk miR-26a to determine whether miR-26a milk concentration might have a long-lasting impact on adipose tissue in the progeny. In the in vitro model, both over- and under-expression of miR-26a were induced by transfecting into 3T3-L1 with miR-26a mimic and inhibitor. Array analysis was performed after induction of miR-26a to ascertain the impact on mRNA target genes and influence of differentiation status. Focusing on genes related to adipose tissue development, transfection with miR-26a mimic reduced the expression of Pten, Hmga1, Stk11, Rb1, and Adam17 in both pre- and mature adipocytes. Data mostly confirmed the results found in the animal model. After weaning, descendants of cafeteria-fed dams breastfed with lower levels of miR-26a displayed greater expression of Hmag1, Rb1, and Adam17 in retroperitoneal white adipose tissue in comparison with controls. Hence, alterations in the amount of miR-26a supplied through milk during lactation is able to alter the expression of target genes in the descendants and may affect adipose tissue development. Thus, milk miR-26a may act as an epigenetic regulator influencing early metabolic program in the progeny, which emerges as a relevant component of an optimal milk composition for correct development.

Alterations in plasma acylcarnitine and amino acid profiles may indicate poor nutrition during the suckling period due to maternal intake of an unbalanced diet and may predict later metabolic dysfunction.

Plasma profiles of acylcarnitines (ACs) and amino acids (AAs) may have interest as potential biomarkers. Here we analyzed plasma AC and AA profiles in 2 rat models with different metabolic programming outcomes: offspring of dams fed a cafeteria diet during lactation (O-CAF, with a thin-outside-fat-inside phenotype) and the offspring of dams with diet-induced obesity subjected to dietary normalization before gestation [offspring of postcafeteria dams (O-PCaf), nonaltered phenotype]. The purpose was to identify early variables that might indicate a propensity for a dysmetabolic state. O-CAF rats presented higher circulating levels of most of the lipid-derived ACs and higher hepatic expression of genes related to fatty acid oxidation ( Ppara and Cpt1a) than controls [offspring of control dams (O-C)]. They also exhibited an altered plasma AA profile. These differences were not observed in O-PCaf animals. A partial least squares-discriminant analysis score plot of the metabolomics data showed a clear separation between O-CAF and O-C animals. The long-chain ACs (C18, C18:1, C18:2, C16:1, and C16DC) and the AAs glycine, alanine, isoleucine, serine, and proline are the variables mainly influencing this separation. In summary, we have identified a cluster of ACs and AAs whose alterations may indicate poor nutrition during lactation due to maternal unbalanced diet intake and predict the later dysmetabolic phenotype observed in the offspring.-Pomar, C. A., Kuda, O., Kopecky, J., Rombaldova, M., Castro, H., Picó, C., Sánchez, J., Palou, A. Alterations in plasma acylcarnitine and amino acid profiles may indicate poor nutrition during the suckling period due to maternal intake of an unbalanced diet and may predict later metabolic dysfunction.

miR-222 exerts negative regulation on insulin signaling pathway in 3T3-L1 adipocytes.

Increased miR-222 levels are associated with metabolic syndrome, insulin resistance, and diabetes. Moreover, rats fed an obesogenic diet during lactation have higher miR-222 content in breast milk and the offspring display greater body fat mass and impaired insulin sensitivity in adulthood. In order to investigate the molecular mechanisms involved and to dissect the specific effects of miR-222 on adipocytes, transfection with a mimic or an inhibitor of miR-222 has been conducted on 3T3-L1 preadipocytes. 3T3-L1 cells were transfected with either a mimic or an inhibitor of miR-222 and collected after 2 days (preadipocytes) or 8 days (mature adipocytes) for transcriptomic analysis. Results showed a relevant impact on pathways associated with insulin signaling, lipid metabolism and adipogenesis. Outcomes in key genes and proteins were further analyzed with quantitative reverse transcription polymerase chain reaction and Western Blotting, respectively, which displayed a general inhibition in important effectors of the identified routes under miR-222 mimic treatment in preadipocytes. Although to a lesser extent, this overall signature was maintained in differentiated adipocytes. Altogether, miR-222 exerts a direct effect in metabolic pathways of 3T3-L1 adipocytes that are relevant to adipocyte function, limiting adipogenesis and insulin signaling pathways, offering a mechanistic explanation for its reported association with metabolic diseases.

Dietary Improvement during Lactation Normalizes miR-26a, miR-222 and miR-484 Levels in the Mammary Gland, but Not in Milk, of Diet-Induced Obese Rats.

We aimed to evaluate in rats whether the levels of specific miRNA are altered in the mammary gland (MG) and milk of diet-induced obese dams, and whether improving maternal nutrition during lactation attenuates such alterations. Dams fed with a standard diet (SD) (control group), with a Western diet (WD) prior to and during gestation and lactation (WD group), or with WD prior to and during gestation but moved to SD during lactation (Rev group) were followed. The WD group showed higher miR-26a, miR-222 and miR-484 levels than the controls in the MG, but the miRNA profile in Rev animals was not different from those of the controls. The WD group also displayed higher miR-125a levels than the Rev group. Dams of the WD group, but not the Rev group, displayed lower mRNA expression levels of Rb1 (miR-26a's target) and Elovl6 (miR-125a's target) than the controls in the MG. The WD group also presented lower expression of Insig1 (miR-26a's target) and Cxcr4 (miR-222's target) than the Rev group. However, both WD and Rev animals displayed lower expression of Vegfa (miR-484's target) than the controls. WD animals also showed greater miR-26a, miR-125a and miR-222 levels in the milk than the controls, but no differences were found between the WD and Rev groups. Thus, implementation of a healthy diet during lactation normalizes the expression levels of specific miRNAs and some target genes in the MG of diet-induced obese dams but not in milk.

Implementation of a healthy diet to lactating rats attenuates the early detrimental programming effects in the offspring born to obese dams. Putative relationship with milk hormone levels.

Lactation is a critical period of development and alterations in milk composition due to maternal diet or status may affect infant growth. We aimed to evaluate in rats whether improving maternal nutrition during lactation attenuates early imprinted adverse metabolic effects in the offspring born to obese dams. Three groups were studied: Control (C) dams, fed with standard diet; Western diet (WD) dams, fed with WD 1 month prior to gestation and during gestation and lactation; and Reversion (Rev) dams, fed as WD-dams, but moved to a standard diet during lactation. Macronutrient content, insulin, leptin and adiponectin levels were determined in milk. Phenotypic traits and circulating parameters in dams and their offspring were determined throughout lactation. Results showed that, at weaning, WD-dams displayed lower body weight and greater plasma insulin and non-esterified fatty acids levels than C-dams, and signs of hepatic steatosis. Milk from WD-dams showed lower protein content and insulin, leptin, and adiponectin levels during the entire or the late lactation. Rev-dams retained excess body fat content, but milk composition and most circulating parameters were not different from controls at late lactation and showed higher leptin mRNA levels in mammary gland than WD-dams. The offspring of WD-dams, but not that of Rev-dams, displayed higher body weight, adiposity, and circulating leptin and glucose levels than controls at weaning. In conclusion, dietary improvement during lactation prevents early adverse effects in offspring associated with maternal intake of an obesogenic diet, that may be related with the normalization of milk hormone levels.

Increased mRNA Levels of ADAM17, IFITM3, and IFNE in Peripheral Blood Cells Are Present in Patients with Obesity and May Predict Severe COVID-19 Evolution.

Gene expression patterns in blood cells from SARS-CoV-2 infected individuals with different clinical phenotypes and body mass index (BMI) could help to identify possible early prognosis factors for COVID-19. We recruited patients with COVID-19 admitted in Hospital Universitari Son Espases (HUSE) between March 2020 and November 2021, and control subjects. Peripheral blood cells (PBCs) and plasma samples were obtained on hospital admission. Gene expression of candidate transcriptomic biomarkers in PBCs were compared based on the patients' clinical status (mild, severe and critical) and BMI range (normal weight, overweight, and obesity). mRNA levels of ADAM17, IFITM3, IL6, CXCL10, CXCL11, IFNG and TYK2 were increased in PBCs of COVID-19 patients (n = 73) compared with controls (n = 47), independently of sex. Increased expression of IFNE was observed in the male patients only. PBC mRNA levels of ADAM17, IFITM3, CXCL11, and CCR2 were higher in those patients that experienced a more serious evolution during hospitalization. ADAM17, IFITM3, IL6 and IFNE were more highly expressed in PBCs of patients with obesity. Interestingly, the expression pattern of ADAM17, IFITM3 and IFNE in PBCs was related to both the severity of COVID-19 evolution and obesity status, especially in the male patients. In conclusion, gene expression in PBCs can be useful for the prognosis of COVID-19 evolution.

Cafeteria Diet Consumption during Lactation in Rats, Rather than Obesity Per Se, alters miR-222, miR-200a, and miR-26a Levels in Milk.

SCOPE: The aim of the present study is to investigate in nursing rats the impact of cafeteria-diet feeding during lactation (cafeteria dams) on specific miRNA levels in breast milk and to discern them from the effects of maternal adiposity per se (postcafeteria dams). METHODS AND RESULTS: Milk samples are collected from control, cafeteria, and postcafeteria dams at three time points of lactation (days 5, 10, and 15) and levels of selected miRNAs (miR-222, miR-203, miR-200a, miR-103, miR-27a, and miR-26a) were determined. Levels in milk of miR-222 rise while miR-103 and miR-27 fall throughout lactation. Moreover, at day 15 of lactation, cafeteria dams present higher miR-222 and lower miR-200a and miR-26a levels in milk than controls. No differences are found in postcafeteria dams compared with controls. At weaning, the offspring of cafeteria dams, but not the offspring of postcafeteria dams, displays lower expression levels of Cdkn1c (a validated target gene of miR-222) in liver than controls. CONCLUSION: Cafeteria diet intake in nursing rats, rather than obesity per se, leads to alterations in specific miRNA levels, which, through the milk supply, may alter expression of target genes and potentially affect offspring phenotype.