VITAMIN D ALLEVIATES AN EXCESSIVE INFLAMMATORY RESPONSE BY INHIBITING THE EXPRESSION OF DCS SURFACE MOLECULES IN THE LUNGS OF YOUNG RATS WITH SEPSIS

Qing He^{1, #}, Yi Yang^{2, 3}, Pinglin Zhang⁴, Lijun Su⁴, Xinghui Zheng^{4, *}

¹Department of Neonatology, Affiliated Hospital of Guizhou Medical University, Guiyang 550000, Guizhou Province, China - ²Department of Children' s rehabilitation, The Third Affiliated Hospital of Zunyi Medical University/Zunyi First People's Hospital, Zunyi 563000, Guizhou Province, China - ³Department of Children's Rehabilitation, Zunyi First People's Hospital, Zunyi 563000, Guizhou Province, China - ⁴Department of Neonatology, The Third Affiliated Hospital of Zunyi Medical University/Zunyi First People's Hospital, Zunyi 563000, Guizhou Province, China

^#These authors contributed equally to this work as co-first author

Objective: To explore the mechanism by which vitamin D (VitD) inhibits the expression of surface molecules on lung dendritic cells (DCs) of young rats with sepsis to reduce the body's excessive inflammatory response. 

Methods: Healthy and clean male Sprague–Dawley pups were selected and the random number table method was used to divide all pups into a control group, a sepsis group, and a VitD intervention group. After establishing the sepsis model, blood was drawn from the young rats to test the serum 25(OH)D3 level; the lung tissue of the young rats was collected and the enzyme-linked immunosorbent assay (ELISA) was used to determine the serum interleukin-12 (IL-12) and tumor necrosis factor -α (TNF-α) level; flow cytometry was used to measure the expression rate of the DC surface molecules CD86 and CD83; HE staining was carried out and the pathological morphology of the lung tissue of each group of young rats was observed, and the infiltration of inflammatory cells was evaluated. 

Results: Compared with the control group, the 3-day survival rate, serum 25(OH)D3 level, serum IL-12 and TNF-α levels, and the lung surface DCs on young rats in the sepsis group and VitD intervention group were significantly reduced (P<0.05) The expression rates of molecular CD86 and CD83 were significantly increased (P<0.05); compared with the sepsis group, the 3-day survival rate, serum 25(OH)D3 levels of young rats in the VitD intervention group were significantly increased (P<0.05), and levels of serum IL-12 and TNF-α, and the expression rates of CD86 and CD83 on the surface of lung DCs were significantly reduced (P<0.05). The lung tissue and pathological structure of the control pups were normal, and there was no inflammatory cell infiltration in the lung interstitium; the lung tissues of the sepsis group pups showed swelling of alveolar epithelial cells, accompanied by congestion and pulmonary interstitial congestive edema, and a large amount of inflammatory cell infiltration: The degree of swelling of lung alveolar epithelial cells in the VitD intervention group was slightly lower in the sepsis group; the congestion and congestive edema were reduced, and there was a small amount of inflammatory cell infiltration. 

Conclusion: VitD can reduce the body’s excessive inflammatory response by inhibiting the expression of surface molecules of DCs in the lungs of young rats with sepsis.