Effects of methionine partially replaced by methionyl-methionine dipeptide on intestinal function in methionine-deficient pregnant mice

Physiological function of gut microbiota and metabolome on successful pregnancy and lactation in the captive Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)†

Gestation period in captive Yangtze finless porpoise (YFP) is a well-coordinated and dynamic process, involving both systemic and local alterations. The gut microbiota and its connection to fecal metabolites are crucial in supporting fetal development and ensuring maternal health during reproductive stages. This study evaluates changes in the gut microbiota and their correlation with fecal metabolites in captive YFPs during different reproductive stages. The results reveal that microbial community structure changed significantly during reproductive stages, while gut microbial diversity remained stable. The genus unclassified Peptostrptococcaceae, Corynebacterium, and norank KD4-96 were significantly greater in non-pregnancy (NP), Terrisporobacter was significantly greater in lactating (LL), and Clostridium was significantly higher in early-pregnancy (EP) compared to the other groups. The host fecal metabolome exhibited significant alterations during the reproductive stages. Indoxyl sulfate, octadecatrienoic acid, and methionyl-methionine were significantly higher in the NP; galactosylglycerol, chondroitin 6-sulfate, and lumichrome were significantly higher in the EP and mid-pregnancy (MP); and valylleucine and butyryl-l-carnitine were significantly higher in the LL. The altered metabolites were mostly concentrated in pathways associated with arachidonic acid metabolism (significantly altered in NP), leucine, valine, and isoleucine biosynthesis (significantly altered in EP and MP), and glycerophospholipid metabolism (significantly altered in LL compared to others stages). Additionally, we found a strong link between variations in the host metabolism and alterations in the fecal bacteria of captive YFP. In conclusion, this study provides detailed insights into host metabolic and fecal bacterial changes in captive YFP during reproduction stages, providing important knowledge for improving the reproductive management in the captive YFP.

Placental and fetal enrichment of microplastics from disposable paper cups: implications for metabolic and reproductive health during pregnancy

The disposable paper cups (DPCs) release millions of microplastics (MPs) when used for hot beverages. However, the tissue-specific deposition and toxic effects of MPs and associated toxins remain largely unexplored, especially at daily consumption levels. We administered MPs and associated toxins extracted from leading brand DPCs to pregnant mice, revealing dose-responsive harmful effects on fetal development and maternal physiology. MPs were detected in all 13 examined tissues, with preferred depositions in the fetus, placenta, kidney, spleen, lung, and heart, contributing to impaired phenotypes. Brain tissues had the smallest MPs (90.35 % < 10 µm). A dose-responsive shift in the cecal microbiome from Firmicutes to Bacteroidetes was observed, coupled with enhanced biosynthesis of microbial fatty acids. A moderate consumption of 3.3 cups daily was sufficient to alter the cecal microbiome, global metabolic functions, and immune health, as reflected by tissue-specific transcriptomic analyses in maternal blood, placenta, and mammary glands, leading to neurodegenerative and miscarriage risks. Gene-based benchmark dose framework analysis suggested a safe exposure limit of 2 to 4 cups/day in pregnant mice. Our results highlight tissue-specific accumulation and metabolic and reproductive toxicities in mice at DPC consumption levels presumed non-hazardous, with potential health implications for pregnant women and fetuses.

Targeted delivery of rosuvastatin enhances treatment of hyperhomocysteinemia-induced atherosclerosis using macrophage membrane-coated nanoparticles

Rosuvastatin (RVS) is an excellent drug with anti-inflammatory and lipid-lowering properties in the academic and medical fields. However, this drug faces a series of challenges when used to treat atherosclerosis caused by hyperhomocysteinemia (HHcy), including high oral dosage, poor targeting, and long-term toxic side effects. In this study, we applied nanotechnology to construct a biomimetic nano-delivery system, macrophage membrane (Møm)-coated RVS-loaded Prussian blue (PB) nanoparticles (MPR NPs), for improving the bioavailability and targeting capacity of RVS, specifically to the plaque lesions associated with HHcy-induced atherosclerosis. In vitro assays demonstrated that MPR NPs effectively inhibited the Toll-like receptor 4 (TLR4)/hypoxia-inducible factor-1α (HIF-1α)/nucleotide-binding and oligomerization domain (NOD)-like receptor thermal protein domain associated protein 3 (NLRP3) signaling pathways, reducing pyroptosis and inflammatory response in macrophages. Additionally, MPR NPs reversed the abnormal distribution of adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1)/ATP binding cassette transporter G1 (ABCA1)/ATP binding cassette transporter G1 (ABCG1) caused by HIF-1α, promoting cholesterol efflux and reducing lipid deposition. In vivo studies using apolipoprotein E knockout (ApoE -/-) mice confirmed the strong efficacy of MPR NPs in treating atherosclerosis with favorable biosecurity, and the mechanism behind this efficacy is believed to involve the regulation of serum metabolism and the remodeling of gut microbes. These findings suggest that the synthesis of MPR NPs provides a promising nanosystem for the targeted therapy of HHcy-induced atherosclerosis.

Methionyl-Methionine Dipeptide Enhances Mammogenesis and Lactogenesis by Suppressing the Expression of a Novel Long Noncoding RNA MGPNCR to Inhibit eIF4B Dephosphorylation

Previous research has demonstrated that in pregnant mice deficient in l-methionine (Met), the mixture of the dipeptide l-methionyl-l-methionine (Met-Met) with Met was more effective than Met alone in promoting mammogenesis and lactogenesis. This study aimed to investigate the role of a novel long noncoding RNA (lncRNA), named mammary gland proliferation-associated lncRNA (MGPNCR), in these processes. Transcriptomic analysis of mammary tissues from Met-deficient mice, supplemented either with a Met-Met/Met mixture or with Met alone, revealed significantly higher MGPNCR expression in the Met group compared to the mixture group, a finding recapitulated in a mammary epithelial cell model. Our findings suggested that MGPNCR hindered mammogenesis and milk protein synthesis by binding to eukaryotic initiation factor 4B (eIF4B). This interaction promoted the dephosphorylation of eIF4B at serine-422 by enhancing its association with protein phosphatase 2A (PP2A). Our study sheds light on the regulatory mechanisms of lncRNA-mediated dipeptide effects on mammary cell proliferation and milk protein synthesis. These insights underscore the potential benefits of utilizing dipeptides to improve milk protein in animals and potentially in humans.

Parenterally Delivered Methionyl-Methionine Dipeptide During Pregnancy Enhances Mammogenesis and Lactation Performance Over Free Methionine by Activating PI3K-AKT Signaling in Methionine-Deficient Mice

BACKGROUND

Pregnancy-induced hypoaminoacidemia, l-methionine (Met) included, disturbs embryogenesis and may also affect breast function. Supplementation with the dipeptide l-methionyl-Met (Met-Met) may improve lactation performance.

OBJECTIVE

We compared the effects of supplemental Met or Met-Met during pregnancy on mammogenesis and lactogenesis and investigated underlying mechanisms.

METHODS

In experiment 1, 9-wk-old ICR mice (n = 72, ∼30 g) were divided into 3 groups. During the first 17 days of pregnancy (DP), the Control group was fed a diet with Met (8.2 g/kg) and saline was intraperitoneally injected, the Met group was fed a Met-devoid diet and 35% of the Met (92-mmo l Met) as contained in the Control diet was intraperitoneally injected, and the Met-Met group was fed the same diet and 70-mmo l Met plus 11-mmo l Met-Met was intraperitoneally injected. All animals were fed the Control diet after DP17 and during lactation. Mammogenesis, lactogenesis, transcriptome at DP17, and milk performance during lactation were examined. In experiment 2, 9-wk-old ICR mice (n = 55, ∼30 g) at DP0 were injected through the teat with adeno-associated virus for overexpression/inhibition of phosphoinositide-3-kinase regulatory subunit 1 (Pik3r1), divided into the Control, Met, and Met-Met groups and received the same treatment as experiment 1 to examine mammogenesis and lactogenesis at DP17.

RESULTS

In experiment 1, compared with the Met group, the Met-Met group showed higher (P < 0.05) mammary epithelium percentage (42%) and αS1-casein expression (84%) at DP17, milk yield (34%) and energy concentrations (8.7%) during lactation; transcriptomic analysis illustrated activated phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT) signaling in the mammary glands of the Met-Met group (P-adj < 0.001). In experiment 2, overexpression of Pik3r1 enhanced (P < 0.05) the protective effect of Met-Met over Met on mammogenesis and β-casein expression.

CONCLUSION

Met-Met is more effective than Met in promoting mammogenesis and lactogenesis mainly by activation of PI3K-AKT signaling in Met-deficient mice.