Melatonin alleviates necrotizing enterocolitis by reducing bile acid levels through the SIRT1/FXR signalling axis.

Bile acids (BAs) have increasingly been implicated in the onset and progression of necrotizing enterocolitis (NEC); multiple findings have demonstrated their ability to induce damage to the intestinal epithelium, thereby exacerbating disease severity. Although we previously showed that melatonin was able to treat NEC by correcting the Treg/Th17 imbalance, the modulatory effect of melatonin on BAs remains unclear. In this study, we conducted transcriptome analysis on intestinal tissues from patients with NEC and validated these findings. Subsequently, we treated mice with melatonin alone or in combination with an agonist/inhibitor of Sirtuin 1 (SIRT1) to assess faecal and serum BA levels, the expression levels of BA transporters and regulators, and the extent of intestinal injury. Our transcriptome results indicated dysregulation of BA metabolism and abnormal expression of BA transporters in patients with NEC, which were also observed in our NEC mouse model. Furthermore, exogenous BAs were found to aggravate NEC severity in mice. Notably, melatonin effectively restored the aberrant expression of BA transporters, such as apical membrane sodium-dependent bile acid transporters (ASBT), ileal bile acid-binding protein (IBABP), and organic solute transporter-alpha (OST-α), by upregulating SIRT1 expression while reducing farnesoid X receptor (FXR) acetylation, consequently leading to decreased serum and faecal BA levels and mitigated NEC severity. Thus, we propose a potential mechanism through which melatonin reduces BA levels via the SIRT1/FXR signalling axis in an NEC mouse model. Collectively, these results highlight that melatonin holds promise for reducing BA levels and represents a promising therapeutic strategy for treating NEC.

Lung ultrasound-guided fluid resuscitation in neonatal septic shock: A randomized controlled trial.

This randomized controlled trial aimed to determine whether lung ultrasound-guided fluid resuscitation improves the clinical outcomes of neonates with septic shock. Seventy-two patients were randomly assigned to undergo treatment with lung ultrasound-guided fluid resuscitation (LUGFR), or with usual fluid resuscitation (Control) in the first 6 h since the start of the sepsis treatment. The primary study outcome was 14-day mortality after randomization. Fourteen-day mortalities in the two groups were not significantly different (LUGFR group, 13.89%; control group, 16.67%; p = 0.76; hazard ratio 0.81 [95% CI 0.27-2.50]). The LUGFR group experienced shorter length of neonatal intensive care unit (NICU) stays (21 vs. 26 days, p = 0.04) and hospital stays (32 vs. 39 days, p = 0.01), and less fluid was used in the first 6 h (77 vs. 106 mL/kg, p = 0.02). Further, our study found that ultrasound-guided fluid resuscitation can significantly reduce the incidence of acute kidney injury (25% vs. 47.2%, p = 0.05) and intracranial hemorrhage (grades I-II) within 72 h (13.9% vs. 36.1%, p = 0.03). However, no significant difference was found in the resolution of shock within 1 h or 6 h, use of mechanical ventilation or vasopressor support, time to achieve lactate level < 2 mmol/L, and the number of participants developing hepatomegaly in the first 6 h. CONCLUSION: Lung ultrasound is a noninvasive and convenient tool for predicting fluid overload in neonatal septic shock. Fluid resuscitation guided by lung ultrasound can shorten the length of hospital and NICU stays, reduce the amount of fluid used in the first 6 h, and reduce the risk of acute kidney injury and intracranial hemorrhage. TRIAL REGISTRATION: Registered in Guangdong Second Provincial General Hospital: 2021-IIT-156-EK, date of registration: November 13, 2021. And ClinicalTrials.gov: NCT06144463 (retrospectively registered). WHAT IS KNOWN: • Excessive fluid resuscitation in neonates with septic shock had worse outcomes. WHAT IS NEW: • Lung ultrasound should be routinely used to guide fluid resuscitation in neonatal septic shock.

The association of insufficient gestational weight gain in women with gestational diabetes mellitus with adverse infant outcomes: A case-control study.

Background: To investigate the association between insufficient maternal gestational weight gain (GWG) during dietary treatment, and neonatal complications of small-for-gestational-age (SGA) infants born to mothers with Gestational diabetes mellitus (GDM). Methods: A retrospective case-control study was conducted, involving 1,651 infants born to mothers with GDM. The prevalence of a perinatal outcome and maternal GWG were compared among SGA, adequate- (AGA), and large-for-gestational-age (LGA); association with birth weight and GWG was identified using Pearson's correlation analysis; binary logistic regression was performed to determine the odds ratio (OR) associated with SGA. Results: In total, 343 SGA, 1025 AGA, and 283 LGA infants met inclusion criteria. The frequency of SGA infants who were siblings (41.7 vs. 4.3 vs. 1.9%) and composite of complications (19.2 vs. 12.0 vs. 11.7%) were higher in SGA infants than in those in AGA or LGA infants group (both P < 0.01). GWG and pre-partum BMI were lower among the SGA mothers with GDM group (11.7 ± 4.5 kg, 25.2 ± 3.1 kg/m2) than AGA (12.3 ± 4.6 kg, 26.3 ± 3.4 kg/m2) or LGA (14.0 ± 5.1 kg, 28.7 ± 3.9 kg/m2) mothers with GDM group. Binary logistic regression showed that siblings who were SGA (AOR 18.06, 95% CI [10.83-30.13]) and preeclampsia (AOR 3.12, 95% CI [1.34-7.30]) were associated with SGA, but not GWG below guidelines (P > 0.05). The risk of SGA (25.7 vs. 19.1 vs. 14.2%) and FGR (15.3 vs. 10.9 vs. 7.8%) was higher in GWG below guidelines group than those in GWG above and within guidelines group, the risk of low Apgar score (6.4 vs. 3.0 vs. 2.8%) was higher in GWG above guidelines group than that in GWG below and within guidelines group (P < 0.05). Conclusion: Our findings demonstrated that GWG above and below guidelines, compared with GWG within guidelines, had a higher risk of adverse infant outcomes. Our findings also suggested that GWG below guidelines did not increase the risk for SGA, though SGA infants had more adverse outcomes among neonates born to mothers with GDM.

Selective targeting of MD2 attenuates intestinal inflammation and prevents neonatal necrotizing enterocolitis by suppressing TLR4 signaling.

Neonatal necrotizing enterocolitis (NEC) is an inflammatory disease that occurs in premature infants and has a high mortality rate; however, the mechanisms behind this disease remain unclear. The TLR4 signaling pathway in intestinal epithelial cells, mediated by TLR4, is important for the activation of the inflammatory storm in NEC infants. Myeloid differentiation protein 2 (MD2) is a key auxiliary component of the TLR4 signaling pathway. In this study, MD2 was found to be significantly increased in intestinal tissues of NEC patients at the acute stage. We further confirmed that MD2 was upregulated in NEC rats. MD2 inhibitor (MI) pretreatment reduced the occurrence and severity of NEC in neonatal rats, inhibited the activation of NF-κB and the release of inflammatory molecules (TNF-α and IL-6), and reduced the severity of intestinal injury. MI pretreatment significantly reduced enterocyte apoptosis while also maintaining tight junction proteins, including occludin and claudin-1, and protecting intestinal mucosal permeability in NEC rats. In addition, an NEC in vitro model was established by stimulating IEC-6 enterocytes with LPS. MD2 overexpression in IEC-6 enterocytes significantly activated NF-κB. Further, both MD2 silencing and MI pretreatment inhibited the inflammatory response. Overexpression of MD2 increased damage to the IEC-6 monolayer cell barrier, while both MD2 silencing and MI pretreatment played a protective role. In conclusion, MD2 triggers an inflammatory response through the TLR4 signaling pathway, leading to intestinal mucosal injury in NEC. In addition, MI alleviates inflammation and reduces intestinal mucosal injury caused by the inflammatory response by blocking the TLR4-MD2/NF-κB signaling axis. These results suggest that inhibiting MD2 may be an important way to prevent NEC.

Antibiotic-induced depletion of Clostridium species increases the risk of secondary fungal infections in preterm infants.

Preterm infants or those with low birth weight are highly susceptible to invasive fungal disease (IFD) and other microbial or viral infection due to immaturity of their immune system. Antibiotics are routinely administered in these vulnerable infants in treatment of sepsis and other infectious diseases, which might cause perturbation of gut microbiome and hence development of IFD. In this study, we compared clinical characteristics of fungal infection after antibiotic treatment in preterm infants. As determined by 16S rRNA sequencing, compared with non-IFD patients with or without antibiotics treatment, Clostridium species in the intestinal tracts of patients with IFD were almost completely eliminated, and Enterococcus were increased. We established a rat model of IFD by intraperitoneal inoculation of C. albicans in rats pretreated with meropenem and vancomycin. After pretreatment with antibiotics, the intestinal microbiomes of rats infected with C. albicans were disordered, as characterized by an increase of proinflammatory conditional pathogens and a sharp decrease of Clostridium species and Bacteroides. Immunofluorescence analysis showed that C. albicans-infected rats pretreated with antibiotics were deficient in IgA and IL10, while the number of Pro-inflammatory CD11c+ macrophages was increased. In conclusion, excessive use of antibiotics promoted the imbalance of intestinal microbiome, especially sharp decreases of short-chain fatty acids (SCFA)-producing Clostridium species, which exacerbated the symptoms of IFD, potentially through decreased mucosal immunomodulatory molecules. Our results suggest that inappropriate use of broad-spectrum antibiotics may promote the colonization of invasive fungi. The results of this study provide new insights into the prevention of IFD in preterm infants.