Protective effect of Bifidobacterium animalis CGMCC25262 on HaCaT keratinocytes.

Bifidobacteria are the most prevalent members of the intestinal microbiota in mammals and other animals, and they play a significant role in promoting gut health through their probiotic effects. Recently, the potential applications of Bifidobacteria have been extended to skin health. However, the beneficial mechanism of Bifidobacteria on the skin barrier remains unclear. In this study, keratinocyte HaCaT cells were used as models to evaluate the protective effects of the cell-free supernatant (CFS), heat-inactivated bacteria, and bacterial lysate of Bifidobacterium animalis CGMCC25262 on the skin barrier and inflammatory cytokines. The results showed that all the tested samples were able to upregulate the transcription levels of biomarker genes associated with the skin barrier, such as hyaluronic acid synthetase (HAS) and aquaporins (AQPs). Notably, the transcription of the hyaluronic acid synthetase gene-2 (HAS-2) is upregulated by 3~4 times, and AQP3 increased by 2.5 times when the keratinocyte HaCaT cells were co-incubated with 0.8 to 1% CFS. In particular, the expression level of Filaggrin (FLG) in HaCaT cells increased by 1.7 to 2.7 times when incubated with Bifidobacterial samples, reaching its peak at a concentration of 0.8% CFS. Moreover, B. animalis CGMCC25262 also decreased the expression of the proinflammatory cytokine RANTES to one-tenth compared to the levels observed in HaCaT cells induced with tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). These results demonstrate the potential of B. animalis CGMCC25262 in protecting the skin barrier and reducing inflammatory response.

Engineered Probiotic Lactococcus lactis for Lycopene Production against ROS Stress in Intestinal Epithelial Cells.

Lactococcus lactis is a food-grade chassis for delivery of bioactive molecules to the intestinal mucosa in situ, while its ability to produce lycopene for detoxification of reactive oxidative species (ROS) is not realized yet. Here, L. lactis NZ9000 was engineered to synthesize lycopene by heterologous expression of a gene cluster crtEBI in plasmids or chromosomes, yielding the recombinant strains NZ4 and NZ5 with 0.59 and 0.54 mg/L lycopene production, respectively. To reroute the pyruvate flux to lycopene, the main lactate dehydrogenase and α-acetolactate synthase pathways were sequentially disrupted. The resultant strains NZΔldh-1 and NZΔldhΔals-1 increased lycopene accumulation to 0.70 and 0.73 mg/L, respectively, while their biomasses were reduced by 12.42% and the intracellular NADH/NAD+ ratios increased by 3.05- and 2.10-fold. To increase the biomasses of these engineered strains, aerobic respiration was activated and tuned by the addition of exogenous heme and oxygen. As a result, the engineered L. lactis strains partly recovered the growth and redox balance, yielding the lycopene levels of 0.91-1.09 mg/L. The engineered L. lactis strain protected the intestinal epithelial cells NCM460 against H2O2 challenge, with a 30.09% increase of cell survival and a 29.2% decrease of the intracellular ROS level compared with strain NZ9000 treatment. In summary, this work established the use of the engineered probiotic L. lactis for lycopene production and prospected its potential in the prevention of intestinal oxidative damage.

Initiation timing effect of levothyroxine treatment on subclinical hypothyroidism in pregnancy.

The aim of this study is to estimate the timing impact on levothyroxine replacement among pregnant women with subclinical hypothyroidism (SCH). Ninety-eight pregnant women diagnosed as SCH in the first trimester were randomly divided into three groups: Group A, instantly initiated levothyroxine after diagnosis; Group B, administrated treatment in the second trimester, and Group C, received no prescription. Incidence of pregnancy complications and pregnancy outcomes were compared among three groups and subgroup analysis were performed stratified with TPO status in Group B. Group A exhibited lower rate of pregnancy complications (9.7%) and adverse outcome (3.2%) than Group B (41.9% and 32.3%) and Group C (64.5% and 38.7%). But the late initiation treatment group shared a comparable complication and maternal outcome with untreated women (p = .075 and .596, respectively). After stratified with TPOAb status in Group B, TPOAb+ women experienced a remarkable lower complication (14.2%) and adverse outcome rate (7.1%) compared with negative subjects (64.7% and 45%, respectively). Our data suggest that levothyroxine administrated in the first trimester was associated with decreased risk of adverse obstetric event. Additionally, pregnant women with TPOAb positive could also benefit from thyroid hormone therapy even initiated in the second trimester.