The effect of mesenchymal stem cell-derived supernatant nasal administration on lung inflammation and immune response in BCG-vaccinated BALB/c mice.

Mesenchymal stem cells (MSCs) are among the known cells that can control and modulate immune responses in different circumstances, including autoimmune diseases. Also, various studies have shown that they can prevent and reduces the pulmonary inflammation caused by infectious agents. In the case of tuberculosis and inflammation caused by BCG, the granuloma has destructive effects and improper orientation of the immune response. Therefore, it is possible to prevent airway damage by preventing harmful inflammatory responses and guiding the immune system responses. This study investigates the role of nasal administration of MSCs supernatant by designing an inflammatory model in the BALB/c mice lung with BCG. MSCs are isolated from mice adipose tissue in this study and evaluated for their phenotypic and differentiation properties. After the third passage, these cells' condition medium (CM) was collected. 20 mice were divided into four groups. Group 1 receive BCG (10 CFU in 5 ml volume for 15 min) nasal administration. Group 2 treated with CM, and group 3 initially were treated with CM (in 5 ml volume for 15 min) and, after 24 h, treated with BCG nasal administration. CM treatment was continued every five days for one month. The fourth group of mice was treated with PBS nasal administration of CM and BCG. One week after the last administration, the lung tissue of mice in each group was pathologically examined. In addition, secretion of IL1-β, IL-6, TNF-α, TGF-β, and IL-10 in the alveolar fluid and secretion of IL-4 and IFN-γ cytokines in the supernatant of splenocytes was evaluated by ELISA. The TNF-α/IL-10 ratio in the alveolar lung fluid of the BCG received group is 2/9 and decreased to 0.58 after successive CM treatment. Therefore, it can be concluded that inflammatory responses to BCG infection in the presence of CM are balanced and pave the way for the induction of effective immune responses by reducing lung tissue damage.