Pediatric intensive care unit treatment alters the diversity and composition of the gut microbiota and antimicrobial resistance gene expression in critically ill children.

Introduction: Common critical illnesses are a growing economic burden on healthcare worldwide. However, therapies targeting the gut microbiota for critical illnesses have not been developed on a large scale. This study aimed to investigate the changes in the characteristics of the gut microbiota in critically ill children after short-term pediatric intensive care unit (PICU) treatments. Methods: Anal swab samples were prospectively collected from March 2021 to March 2022 from children admitted to the PICU of Xinhua Hospital who received broad-spectrum antibiotics on days 1 (the D1 group) and 7 (the D7 group) of the PICU treatment. The structural and functional characteristics of the gut microbiota of critically ill children were explored using metagenomic next-generation sequencing (mNGS) technology, and a comparative analysis of samples from D1 and D7 was conducted. Results: After 7 days of PICU admission, a significant decrease was noted in the richness of the gut microbiota in critically ill children, while the bacterial diversity and the community structure between groups remained stable to some extent. The relative abundance of Bacilli and Lactobacillales was significantly higher, and that of Campylobacter hominis was significantly lower in the D7 group than in the D1 group. The random forest model revealed that Prevotella coporis and Enterobacter cloacae were bacterial biomarkers between groups. LEfSe revealed that two Gene Ontology entries, GO:0071555 (cell wall organization) and GO:005508 (transmembrane transport), changed significantly after the short-term treatment in the PICU. In addition, 30 KEGG pathways were mainly related to the activity of enzymes and proteins during the processes of metabolism, DNA catabolism and repair, and substance transport. Finally, 31 antimicrobial resistance genes had significantly different levels between the D7 and D1 groups. The top 10 up-regulated genes were Erm(A), ErmX, LptD, eptB, SAT-4, tetO, adeJ, adeF, APH(3')-IIIa, and tetM. Conclusion: The composition, gene function, and resistance genes of gut microbiota of critically ill children can change significantly after short PICU treatments. Our findings provide a substantial basis for a better understanding of the structure and function of gut microbiota and their role in critical illnesses.

Analysis of microRNA expression in rat kidneys after VEGF inhibitor treatment under different degrees of hypoxia.

Previously, we found that the incidence of kidney injury in patients with chronic hypoxia was related to the partial pressure of arterial oxygen. However, at oxygen concentrations that contribute to kidney injury, the changes in the relationship between microRNAs (miRNAs) and the hypoxia-inducible factor-1α (HIF-1α)-vascular endothelial growth factor (VEGF) axis and the key miRNAs involved in this process have not been elucidated. Therefore, we elucidated the relationship between VEGF and kidney injury at different oxygen concentrations and the mechanisms mediated by miRNAs. Sprague-Dawley rats were exposed to normobaric hypoxia and categorized into six groups based on the concentration of the oxygen inhaled and injection of the angiogenesis inhibitor bevacizumab, a humanized anti-VEGF monoclonal antibody. Renal tissue samples were processed to determine pathological and morphological changes and HIF-1α, VEGF, and miRNA expression. We performed a clustering analysis of high-risk pathways and key hub genes. The results were validated using two Gene Expression Omnibus datasets (GSE94717 and GSE30718). As inhaled oxygen concentration decreased, destructive changes in the kidney tissues became more severe. Although the kidney possesses a self-protective mechanism under an intermediate degree of hypoxia (10% O2), bevacizumab injections disrupted this mechanism, and VEGF expression was associated with the ability of the kidney to repair itself. rno-miR-124-3p was identified as a crucial miRNA; a key gene target, Mapk14, was identified during this process. VEGF plays an important role in kidney protection from injury under different hypoxia levels. Specific miRNAs and their target genes may serve as biomarkers that provide new insights into kidney injury treatment.NEW & NOTEWORTHY Renal tolerance to hypoxic environments is limited, and the degree of hypoxia does not show a linear relationship with angiogenesis. VEGF plays an important role in the kidney's self-protective mechanism under different levels of hypoxia. miR-124-3p may be particularly important in kidney repair, and it may modulate VEGF expression through the miR-124-3p/Mapk14 signaling pathway. These microRNAs may serve as biomarkers that provide new insights into kidney injury treatment.

Contribution of gut microbiota toward renal function in sepsis.

Sepsis most often involves the kidney and is one of the most common causes of acute kidney injury. The prevalence of septic acute kidney injury has increased significantly in recent years. The gut microbiota plays an important role in sepsis. It interacts with the kidney in a complex and multifactorial process, which is not fully understood. Sepsis may lead to gut microbiota alteration, orchestrate gut mucosal injury, and cause gut barrier failure, which further alters the host immunological and metabolic homeostasis. The pattern of gut microbiota alteration also varies with sepsis progression. Changes in intestinal microecology have double-edged effects on renal function, which also affects intestinal homeostasis. This review aimed to clarify the interaction between gut microbiota and renal function during the onset and progression of sepsis. The mechanism of gut-kidney crosstalk may provide potential insights for the development of novel therapeutic strategies for sepsis.