Immunomodulatory Role of Vitamin D on Gut Microbiome in Children

Changes in Vitamin D and Gut Microbiota in Pediatric Hematopoietic Stem Cell Transplantation Patients with Bloodstream Infections

BACKGROUND

Vitamin D (VD) and gut microbiota (GM) are important variables in pediatric hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infections (BSI). Both VD and GM play significant roles in immune regulation and in maintaining intestinal barrier function.

METHODS

This prospective case-control study included 48 consecutive pediatric patients who underwent HSCT, as well as 20 healthy children from the community. Plasma samples were collected pre- and post-HSCT, together with post-HSCT fecal samples. Serum 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were measured using chemiluminescence and enzyme linked immunosorbent assay, respectively. GM was analyzed by 16S rDNA next generation sequencing.

RESULTS

The incidence of BSI in pediatric HSCT recipients was 33.3% (16/48). No significant differences in serum 25(OH)D or 1,25(OH)2D3 levels were observed between the BSI and non-BSI groups either before or after transplantation, or with the healthy control group. The α-diversity of GM in BSI and non-BSI patients was significantly lower than in healthy subjects. Proteobacteria were significantly more abundant in BSI patients than in non-BSI patients (p = 0.0434) or healthy controls (p = 0.0193). Pediatric HSCT patients showed significantly higher levels of Staphylococcus (p < 0.001), Pseudomonas (p < 0.001), Enterococcus (p < 0.001), Clostridium innocuum (p = 0.0175) and Enterobacter (p = 0.0394) compared to the controls, whereas the levels of Firmicutes (p = 0.009), Actinobacteria (p < 0.001), Bifidobacterium (p < 0.001) and Faecalibacterium (p < 0.001) were significantly lower. β-diversity analysis revealed significant population differences between the three groups.

CONCLUSIONS

These results indicate there is no practical value in monitoring VD in HSCT patients. During HSCT and BSI, the GM experiences a loss of probiotics and an increase in potential pathogens.

V Brazilian Consensus on Rhinitis - 2024

Since we published the "IV Brazilian Consensus on Rhinitis", in2017, several advances have been achieved and have enabled a further understanding of the different aspects of "Rhinitis". This new guideline, developed jointly by ASBAI, SBP and SBORL, represents a relevant milestone in the updated and integrated management of the different forms of the disease, and it aims to unify evidence-based approaches to improve the diagnosis and treatment of this common and often underestimated condition. The document covers a wide range of topics, including clear definitions of the different phenotypes and endotypes of rhinitis, risk factors, updated diagnostic criteria, and recommended methods for clinical and laboratory investigation. We stress the importance of detailed clinical history and objective assessment, as well as tools for control and assessing severity tools an accurate diagnostic approach to the disease. Regarding treatment, it emphasizes the treatment customization, considering the severity of symptoms, the presence of comorbidities and the impact on the patient's quality of life. We discuss different drug treatment, in addition to non-pharmacological measures, such as environmental control and specific immunotherapy; and the possible role of immunobiological agents. Furthermore, the consensus addresses issues related to patient education, prevention and management of special situations, such as rhinitis in children, in pregnant women and in the elderly. In short, the "V Brazilian Consensus on Rhinitis" represents a comprehensive and updated guide for healthcare professionals involved in the diagnosis and management of rhinitis, aiming to improve patients' quality of life through an integrated and evidence-based approach.

Interaction between Vitamin D homeostasis, gut microbiota, and central precocious puberty

Central precocious puberty (CPP) is an endocrine disease in children, characterized by rapid genital development and secondary sexual characteristics before the age of eight in girls and nine in boys. The premature activation of the hypothalamic-pituitary-gonadal axis (HPGA) limits the height of patients in adulthood and is associated with a higher risk of breast cancer. How to prevent and improve the prognosis of CPP is an important problem. Vitamin D receptor (VDR) is widely expressed in the reproductive system, participates in the synthesis and function of regulatory sex hormones, and affects the development and function of gonads. In addition, gut microbiota plays an important role in human health by mainly regulating metabolites, energy homeostasis, and hormone regulation. This review aims to clarify the effect of vitamin D deficiency on the occurrence and development of CPP and explore the role of gut microbiota in it. Although evidence on the interaction between vitamin D deficiency, gut microbiota, and sexual development remains limited, vitamin D supplementation and gut microbiota interventions offer a promising, non-invasive strategy for managing CPP.

Application of PCR-Based Techniques for the Identification of Genetic Fingerprint Diversity of Dominant Bacteria in Fecal Samples of Children with Diarrhea in Vietnam

In Vietnam, diarrhea, especially persistent diarrhea, is one of the most common diseases in children, while a significant proportion of cases are negative with pathogens; thus, there is an urgent need to understand gut bacterial dysbiosis. In this study, bacteria in the fecal samples of five healthy and ten diarrheal children were separated from other residues, then adopted to extract their metagenomic DNA for evaluating their diversity based on V3 and V6-V8 regions and the 16S rRNA gene by PCR-RFLP and PCR-DGGE. As a result, bacterial metagenomic DNAs with high quality, quantity and diversity were successfully extracted using a GeneJET kit and a chemical protocol. A sequence analysis of 73 representative DNA fragments from gels indicated a remarkable bacterial dysbiosis in all groups of diarrhea. Viral diarrhea was characterized by extremely reduced bacterial diversity with the blossom of Bifidobacterium and Streptococcus. Streptococcus was also the most abundant in persistent diarrhea. Beneficial bacteria that may play a role in the self- rebalance in intestinal bacterial communities, such as Bifidobacterium, Lactobacillus, and Enterococcus, were seen in all diarrheal groups, while Bacteroides and Akkermansia muciniphila were seen in the healthy group but absent in the diarrheal groups. This study provides additional evidence for a relationship between intestinal bacterial dysbiosis and diarrhea in children, emphasizing an increase in Streptococcus.

Increased Cadmium Load, Vitamin D Deficiency, and Elevated FGF23 Levels as Pathophysiological Factors Potentially Linked to the Onset of Acute Lymphoblastic Leukemia: A Review

The preventability of acute lymphocytic leukemia during childhood is currently receiving great attention, as it is one of the most common cancers in children. Among the known risk factors so far are those affecting the development of gut microbiota, such as a short duration or absence of breastfeeding, cesarean section, a diet lacking in short-chain fatty acids (SCFAs), the use of antibiotics, absence of infection during infancy, and lack of pets, among other factors. Namely, it has been shown that iron deficiency anemia (IDA) and lack of vitamin D may cause intestinal dysbiosis, while at the same time, both increase the risk of hematological malignancies. The presence of IDA and vitamin D deficiency have been shown to lead to a decreased proportion of Firmicutes in stool, which could, as a consequence, lead to a deficit of butyrate. Moreover, children with IDA have increased blood concentrations of cadmium, which induces systemic inflammation and is linked to the onset of an inflammatory microenvironment in the bone marrow. Finally, IDA and Cd exposure increase fibroblast growth factor 23 (FGF23) blood levels, which in turn suppresses vitamin D synthesis. A lack of vitamin D has been associated with a higher risk of ALL onset. In brief, as presented in this review, there are three independent ways in which IDA increases the risk of acute lymphocytic leukemia (ALL) appearance. These are: intestinal dysbiosis, disruption of vitamin D synthesis, and an increased Cd load, which has been linked to systemic inflammation. All of the aforementioned factors could generate the appearance of a second mutation, such as ETV6/RUNX1 (TEL-AML), leading to mutation homozygosity and the onset of disease. ALL has been observed in both IDA and thalassemia. However, as IDA is the most common type of anemia and the majority of published data pertains to it, we will focus on IDA in this review.

Vitamin D in Health and Disease 2.0

Vitamin D (VD) is a fat-soluble vitamin considered essential for human health, and its levels are associated with the function and composition of the intestinal microbiome [...].