Breast Milk-Derived Limosilactobacillus reuteri Prevents Atopic Dermatitis in Mice via Activating Retinol Absorption and Metabolism in Peyer's Patches.

SCOPE: Supplementing Limosilactobacillus reuteri Fn041, a breast milk-derived probiotic from agricultural and pastoral areas, to maternal mice during late pregnancy and lactation prevents atopic dermatitis (AD) in offspring. This study aims to elucidate the molecular mechanism of Fn041-mediated immune regulation. METHODS AND RESULTS: Fn041 is administered prenatal and postnatal to maternal mice, and to offspring after weaning. The ears are administered with calcipotriol to induce AD. Fn041 treatment significantly alleviates ear inflammation, and reduces mast cell infiltration. Fn041 treatment upregulates and downregulates intestinal ZO-1 and Claudin-2 mRNA expression, respectively. Transcriptome analysis of Peyer's patches reveals that pathways related to DNA damage repair are activated in AD mice, which is inhibited by Fn041 treatment. Fn041 activates pathways related to retinol absorption and metabolism. Untargeted metabolomic analysis reveals that Fn041 treatment increases plasma retinol and kynurenine. Fn041 treatment does not significantly alter the overall cecal microbiota profile, only increases the relative abundances of Ligilactobacillus apodemi, Ligilactobacillus murinus, Akkermansia muciniphila, and Bacteroides thetaiotaomicron. CONCLUSIONS: Fn041 induces anti-AD immune responses directly by promoting the absorption and metabolism of retinol in Peyer's patches, and plays an indirect role by strengthening the mucosal barrier and increasing the abundance of specific anti-AD bacteria in the cecum.

Limosilactobacillus reuteri FN041 prevents atopic dermatitis in pup mice by remodeling the ileal microbiota and regulating gene expression in Peyer's patches after vertical transmission.

Objectives: Limosilactobacillus reuteri FN041 is a potential probiotic bacterium isolated from breast milk in traditional farming and pastoral areas of China. The purpose of this study was to investigate the optimal intervention mode and potential mechanism of FN041 to prevent atopic dermatitis (AD) in mice. Methods: In intervention mode I, FN041 was supplemented to dams during the late trimester and lactation and pups after weaning; in intervention mode II, FN041 was supplemented after pups were weaned. AD was induced in pups with MC903 plus ovalbumin on the ear after weaning. Results: The effect of intervention mode I in preventing AD was significantly better than that of intervention mode II. Compared with the model group, the inflammatory response of the pup's ears, the proportion of spleen regulatory T cells and the plasma IgE were significantly decreased in mice in intervention mode I. Furthermore, the intestinal mucosal barrier was enhanced, and the Shannon index of the ileal microbiota was significantly increased. The microbiota structure deviated from the AD controls and shifted toward the healthy controls according to the PCoA of unweighted UniFrac. The relative abundances of Limosilactobacillus, Faecalibacterium, Bifidobacterium, and Akkermansia in the ileum were significantly increased compared to the AD group. Based on RNA-seq analysis of pups' Peyer's patches (PPs), FN041 inhibits autoimmune pathways such as asthma and systemic lupus erythematosus and activates retinol metabolism and PPAR signaling pathways to reduce inflammatory responses. Intervention mode II also significantly reduced AD severity score, but the reduction was approximately 67% of that of intervention mode I. This may be related to its ineffective remodeling of the ileal microbiota. Conclusion: Prenatal and postnatal administration of FN041 is an effective way to prevent AD in offspring, and its mechanism is related to remodeling of ileal microbiota and PPs immune response.

Widespread vertical transmission of secretory immunoglobulin A coated trace bacterial variants from the mother to infant gut through breastfeeding.

Gut microbiota transmission from mother to offspring is critical to infant gut microbiota and immune development. Mother's intestine and breast milk are rich in secretory immunoglobulin A (sIgA), which can coat a specific bacterial spectrum and may be related to bacterial transmission and colonization. Here we analyzed the microbiota and sIgA-coated bacteria of maternal fecal samples and breast milk and infant fecal samples from 19 dyads by 16S rRNA amplicon sequencing. For the sIgA-coated microbiota, both the phylogenetic diversity and the Shannon index of maternal fecal samples show a lower trend than those of infant fecal samples (P < 0.05). For beta diversity, all three samples were significantly different from each other (P < 0.05, based on permutational multivariate analysis of variance). We found that sIgA mediated a wide range of vertical transmission of trace bacteria with a relative abundance of amplicon sequence variants of more than 0.0001%. FEAST-based analysis reveals that there was an equal contribution of the maternal gut (median [IQR]; 8.75% [0.90, 62.14]) and breast milk (9.23% [1.69, 22.29]) to infant intestinal total microbiota. The 39 percent of sIgA-coated microbiota in breast milk samples provided as much as 28.49-93.84 percent of all sIgA-coated microbiota in the newborn gut. Therefore, maternal gut and breast milk sIgA-coated bacteria are essential sources of intestinal bacteria in infants. There was high individual variation in the contribution of the maternal gut and breast milk microbiota to the paired infant gut microbiota. Analysis based on the weighted transfer ratio (WTR) explained that diverse sIgA-coated bacteria are transferred from breast milk to the gut of the respective infant, mainly lactic acid bacteria, especially Lactobacillus gasseri (WTR = 2475.5), Enterococcus faecium (WTR = 2438) and Streptococcus salivarius (WTR = 117.71). Bifidobacterium longum, with a WTR of 69.35, is the key sIgA-coated bacteria that are transferred from the mother's gut to breast milk. In conclusion, sIgA mediates the vertical transmission of specific bacteria, to realize the controllable inheritance of the intestinal bacteria and function from the mother to the offspring. This provides a new basis for the screening of probiotics for infant formula addition.

Chromosomal microarray analysis versus noninvasive prenatal testing in fetuses with increased nuchal translucency.

OBJECTIVE: To evaluate if the NT value of 2.5 mm ≤ NT < 3.0 mm is an appropriate indication for CMA tests among fetuses with isolated increased NT and NIPT is more suitable instead. METHODS: A total of 442 fetuses with NT ≥ 2.5 mm were included, in which 241 fetuses underwent karyotype. CMA tests were then carried out when cytogenic analysis showed normal chromosomes and CNV status was compared between 2.5 mm ≤ NT < 3.0 mm and ≥3.0 mm subgroups. For the NIPT evaluation, 201 of 442 fetuses with smaller increased NT (2.5 mm ≤ NT < 3.0 mm) was examined by either NIPT or karyotype. RESULTS: Of the 241 fetuses with NT ≥ 2.5 mm, 47(19.50%) were identified by karyotype with chromosomal abnormalities. Among 194 cases with normal karyotype, CMA unraveled additional CNVs in 16(8.25%) cases, including 3(1.55%) pathogenic CNVs, 2(1.03%) likely pathogenic CNVs and 11(5.67%) VOUS. After the subgroup analysis, however, only one case (1.16%) of likely pathogenic was identified by CMA among 86 fetuses with NT between 2.5 mm and 3.0 mm, whereas the rest of 15 CNV cases were all presented in fetuses with NT ≥ 3.0 mm. For the NIPT evaluation, the detection rate of 201 fetuses with isolated increased NT between 2.5 and 3.0 mm was 3.98%, which was indifferent to karyotype with the rate of 5%. In comparison with fetuses with 2.5-3.0 mm combined with other risks, the detection rate of karyotype was 26.92%. CONCLUSION: While no pathogenic CNVs were detected in fetuses, chromosomal aneuploidies and genomic imbalance were found to be the major type of abnormalities when NT was 2.5-3.0 mm. Therefore, our data suggested that CMA should not be recommended when fetuses with an NT value less than 3.0 mm. Instead, NIPT with similar rate of detection as karyotype was recommended for fetuses with isolated increased NT between 2.5 and 3.0 mm.

Lactation-dependent vertical transmission of natural probiotics from the mother to the infant gut through breast milk.

The transmission of certain bacteria from the mother's gut to the infant's gut via breast milk (BM) is critical for the offspring's immune system development. Dysbiosis of the BM microbiota can be caused by a variety of reasons, which can be influenced by probiotics delivered via the enteromammary route. The goal of this study was to investigate the bacteria that can be transmitted from the mother to the infant's intestine during various lactation periods in 19 mother-child dyads. Bacterial transmission is most common during the colostrum phase when bacteria with certain amplicon sequence variants (ASVs) enter the newborn intestine and inhabit it permanently. We have established that anaerobic gut-associated bacteria, such as Faecalibacterium, Blautia and Lachnoclostridium, transfer from the mother to the infant's gut with lactation dependence using the idea of weighted transfer ratios. Streptococcus salivarius, Bifidobacterium longum, and Lactobacillus gasseri are transferred from the maternal gut to the BM, as well as from the BM to the newborn gut, depending on different ASVs. These findings suggest that isolation of key microorganisms from breast milk could be utilized to modify the microbiota of BM or newborns by giving the mother a probiotic or adding it to artificial milk to promote neonatal health.

Expanding the application of non-invasive prenatal testing in the detection of foetal chromosomal copy number variations.

PURPOSE: The aim of this study was to assess the detection efficiency and clinical application value of non-invasive prenatal testing (NIPT) for foetal copy number variants (CNVs) in clinical samples from 39,002 prospective cases. METHODS: A total of 39,002 pregnant women who received NIPT by next-generation sequencing (NGS) with a sequencing depth of 6 M reads in our centre from January 2018 to April 2020 were enrolled. Chromosomal microarray analysis (CMA) was further used to diagnose suspected chromosomal aneuploidies and chromosomal microdeletion/microduplication for consistency assessment. RESULTS: A total of 473 pregnancies (1.213%) were positive for clinically significant foetal chromosome abnormalities by NIPT. This group comprised 99 trisomy 21 (T21, 0.254%), 30 trisomy 18 (T18, 0.077%), 25 trisomy 13 (T13, 0.064%), 155 sex chromosome aneuploidy (SCA, 0.398%), 69 rare trisomy (0.177%), and 95 microdeletion/microduplication syndrome (MMS, 0.244%) cases. Based on follow-up tests, the positive predictive values (PPVs) for the T21, T18, T13, SCA, rare trisomy, and MMS cases were calculated to be 88.89%, 53.33%, 20.00%, 40.22%, 4.88%, and 49.02%, respectively. In addition, the PPVs of CNVs of < 5 Mb, 5-10 Mb, and > 10 Mb were 54.55%, 38.46%, and 40.00%, respectively. Among the 95 cases with suspected CNVs, 25 were diagnosed as true positive and 26 cases as false positive; follow-up prenatal diagnosis by CMA was not performed for 44 cases. Moreover, among the 25 true positive cases, 10 were pathogenic, 3 were likely pathogenic, and 12 were of uncertain significance. CONCLUSION: NIPT is not only suitable for screening T21, T18, T13, and SCA but also has potential significance for CNV detection. As combined with ultrasound, extended NIPT is effective for screening MMS. However, NIPT should not be recommended for whole-chromosome aneuploidy screening.

[Application of in situ amniocyte culture for prenatal diagnosis].

OBJECTIVE: To explore the value of in situ amniocyte culture for prenatal diagnosis. METHODS: 2716 amniotic fluid samples were cultured in situ on slides. After the culture, the slides were stained, photographed and analyzed. RESULTS: All samples were successfully analyzed, with the success rates for primary culture and subculture being 98.42% and 1.58%, respectively. 224 samples (8.25%) were detected with chromosomal aberrations, which included 125 cases with trisomy 21, 31 with trisomy 18, 3 with trisomy 13, 4 with 45,X, 17 with 47,XXY, 5 with 47,XYY, 1 with 48,XXY,+18, 1 with 48,XXYY, 26 with structural chromosomal aberrations, and 11 with mosaicisms for aneuploidies. CONCLUSION: In situ amniocyte culture is stable and has a high success rate, and is capable of identifying true and false mosaicisms, which can improve the accuracy of prenatal diagnosis.

H2B ubiquitination regulates meiotic recombination by promoting chromatin relaxation.

Meiotic recombination is essential for fertility in most sexually reproducing species, but the molecular mechanisms underlying this process remain poorly understood in mammals. Here, we show that RNF20-mediated H2B ubiquitination is required for meiotic recombination. A germ cell-specific knockout of the H2B ubiquitination E3 ligase RNF20 results in complete male infertility. The Stra8-Rnf20-/- spermatocytes arrest at the pachytene stage because of impaired programmed double-strand break (DSB) repair. Further investigations reveal that the depletion of RNF20 in the germ cells affects chromatin relaxation, thus preventing programmed DSB repair factors from being recruited to proper positions on the chromatin. The gametogenetic defects of the H2B ubiquitination deficient cells could be partially rescued by forced chromatin relaxation. Taken together, our results demonstrate that RNF20/Bre1p-mediated H2B ubiquitination regulates meiotic recombination by promoting chromatin relaxation, and suggest an old drug may provide a new way to treat some oligo- or azoospermia patients with chromatin relaxation disorders.