Immune Responses Against Allergic Asthma Following Intervention with Lacticaseibacillus paracasei DMLA16017 and Vitamin D in Rats

Objectives: Allergic asthma (AA) is an increasing public health concern. The aim of this study was to investigate the potential effects of immune responses against AA in rats following intervention with Lacticaseibacillus paracasei DMLA16017 and vitamin D (VD). Methods: L. paracasei DMLA16017 was identified using 16S rDNA sequencing, while a rat model of AA was established via ovalbumin (OVA) induction. Subsequently, samples were collected for biomarker analysis in peripheral blood and lung tissue (including serum OVA-immunoglobulin E (IgE) and cytokines) using enzyme-linked immunosorbent assays and assessment of the composition of the intestinal microbiota and species diversity using 16S rRNA sequencing. Results: In the rat model, OVA-induced sensitization induced significant physiological alterations, including pulmonary tissue damage, elevated white cell counts, increased serum levels of OVA-IgE and cytokines interleukin (IL)-4 and IL-17, and reduced levels of IFN-γ and TGF-β. These changes were accompanied by dysbiosis of the gut microbiota and decreased species diversity. Co-administration of VD and DMLA16017 effectively ameliorated the physiological disturbances and histopathological abnormalities in rats with AA, restored the balance between cellular and immune responses, and improved the composition of the gut microbiota and species diversity. Conclusions: Combined intervention with VD and DMLA16017 can be used to treat AA disorders, with potential long-term modulation of the immune system.