Background: The main source of vitamin D is skin synthesis, which depends on sunlight exposure. During the pandemic, COVID-19 children were obliged to home confinement, which potentially limiting sunlight exposure. The aim of this study was to evaluate whether home confinement led to decreased vitamin D serum levels in children in Warsaw, Poland. Methods: The study included 1472 children who were divided into two groups, based on the date of 25(OH)D level blood sampling: before and during the pandemic. Children under 1 year of age (infants) were analysed separately. Results: A statistically significant decrease in the average level of vitamin D was observed between groups of children over 1 year of age (35 ng/mL ± 18 vs. 31 ng/mL ± 14). In infants from both groups, the mean vitamin D levels were within the normal range (Group 1 inf 54 ng/mL ± 21 vs. Group 2 inf 47 ng/mL ± 15). The characteristic seasonal variability was observed before the pandemic, with maximal vitamin D levels in summer (40 ng/mL ± 17) and minimal levels in winter (30 ng/mL ± 14). During the pandemic, no seasonal variability was observed (summer 30 ng/mL ± 11 vs. winter 30 ng/mL ± 19). Conclusions: The COVID-19 pandemic restrictions led to a significant decrease in vitamin D serum levels in children.

Recent studies suggest that the content of immune components in milk is influenced by the mother’s health and also by the infant she feeds. We aimed to evaluate the effect of a child’s respiratory tract infection on the cellular composition of breast milk (neutrophils, monocytes, eosinophils, lymphocytes, and their subpopulations). Twenty-six breastfeeding mothers whose children were hospitalized for respiratory tract infections were enrolled in the study. The control group consisted of 23 mothers of healthy children. Regarding the children, baseline laboratory blood tests were performed, and nasal swabs were taken for the presence of RS virus. In the next step, milk samples were collected from the mothers to assess the cellular composition of the milk, including neutrophils, monocytes, eosinophils, lymphocytes, and their subpopulations. Significantly higher percentages of T lymphocytes (helper and cytotoxic lymphocytes) were observed in the milk of the studied mothers. There was a significantly higher percentage of milk lymphocytes in the group of affected children with confirmed RSV etiology than in children with excluded RSV etiology. A significant positive correlation was observed between the duration of infection and the percentage of milk NK cells and between milk CD19 lymphocytes and the child’s serum leukocytosis. This study may provide evidence of a link between cells in breast milk and disease in the breastfed infant. The severity of the infection, its duration, and the etiological agent of the infection may affect the cellular composition of milk.

The kidney deterioration, which starts in childhood often leads to end-stage renal failure in the future. Therefore, searching for an early, sensitive, and specific biomarkers became a paramount for chronic kidney disease diagnosis. The aim of this study was the assessment of markers: KIM-1, FGF-23, NAG, NGAL, and uromodulin for diagnosis of preclinical phase of the disease in children. 59 children (15 boys, 44 girls from 6 months to 17 years old) with kidney disorders, which had clinical indications for renoscintigraphy, were included in the study. All patients were divided depending on the result of renoscintigraphy (renal scarring vs normal kidney picture) and depending on the level of estimated glomerular filtration rate (glomerular hyperfiltration vs normal filtration rate). The concentration of uromoduline, KIM-1, FGF-23, NAG, and NGAL in serum and of NGAL and uromoduline in urine were measured in all studied groups. The children with glomerular hyperfiltration had a statistically significantly higher serum values of FGF-23 and NGAL than the children with normal filtration rate (P < .05). There were no statistically significant differences in serum concentrations of tested markers in children with renal scars in comparison to children with normal renal image. There was no statistically significant difference in the concentration of tested markers in urine. The study confirmed the possible usefulness of FGF-23 and NGAL in detecting the preclinical-stage of renal disease associated with glomerular hyperfiltration in children. The study do not allow to indicate markers, which could be useful in the early diagnosis of kidney damage visible in the scintigraphic examination.

Introduction Infections caused by Enterobacteriaceae producing extended-spectrum -lactamases (ESBLs) are a serious therapeutic and clinical problem. An increasing role of ESBL(+) pathogens is observed in both community- and hospital-acquired infections. Aim of the study was to assess the...

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by eczematous lesions and recurrent pruritus. The pathogenesis of AD involves epidermal barrier impairments, immune dysfunction, and both genetic and environmental factors. This review presents the latest findings regarding the involvement of microRNA (miRNA) molecules in AD pathogenesis and their potential application as diagnostic biomarkers and therapeutic targets. The following miRNAs were analyzed in detail: miR-223, miR-10a-5p, miR-29b, miR-146a-5p, miR-451a, miR-124, miR-143, miR-151a, miR-24, miR-191, and miR-155. Their molecular mechanisms and potential clinical implications are discussed. Understanding the role of specific microRNAs in AD pathogenesis may contribute to the development of new diagnostic and therapeutic strategies for this disease.

Purpose of review: Regulatory B cells (Bregs) are a key component in the regulation of the immune system. Their immunosuppressive function, which includes limiting the inflammatory cascade, occurs through interactions with other immune cells and the secretion of cytokines, primarily IL-10. As knowledge about B cells continues to expand, their diversity is becoming more recognized, with many subpopulations identified in both human and animal models. However, identifying specific transcription factors or markers that could definitively distinguish regulatory B cells remains a challenge. This review summarizes recent findings on the role of B regulatory cells in allergic diseases. Recent findings: In patients with bronchial asthma, atopic dermatitis, and food allergies, the number of regulatory B cells is reduced, and disease severity is inversely proportional to the quantity of these cells. Furthermore, in patients with atopic dermatitis, the ability of regulatory B cells to produce IL-10 in response to IL-6 stimulation is diminished. However, allergen immunotherapy has been shown to induce the formation of regulatory T cells as well as regulatory B cells. Summary: The success of future therapies based on B cells may depend on deepening our current understanding of their phenotypes, induction, differentiation, and function. Research in these areas is essential for understanding the mechanisms regulating Breg activity and for developing potential targeted therapies in the treatment of allergic diseases.