Background/Objectives: Acute pneumonia remains one of the leading causes of mortality worldwide. The pathogenesis of the disease is determined by the nature of the host immune response. The balance between effector and regulatory T cells (Treg) is critical, as it determines the severity of inflammation and the regenerative capacity of lung tissue. The development of new approaches to modulate the immune response using promising synthetic compounds opens up the possibility of targeted cytokine balance restoration of cytokine balance and Tregs functions This study investigated the effects of the newly synthesized complex of 1-(2-Ethoxypropyl)-4-(pent-1-yn-1-yl)piperidin-4-yl Propionate with β-Cyclodextrin (MXF-22), on the populations of CD4⁺, CD4⁺CD25⁺ and CD4⁺FoxP3⁺ T cells in an oleic acid-induced acute lung injury rat model. Methods: Quantitative analysis of CD4⁺, CD4⁺CD25⁺, and CD4⁺FoxP3⁺ T cell subsets and serum IL-4 and TGF-β levels were determined by flow cytometry and ELISA assays, respectively. Results: The study revealed a significant decrease in the number of CD4⁺ T cells and their regulatory subsets (CD4⁺CD25⁺, CD4⁺FoxP3⁺) during acute pneumonia. Oral administration of MXF-22 contributed to a pronounced recovery of these parameters, accompanied by increased levels of IL-4 and TGF-β, which indicated the activation of anti-inflammatory and reparative processes. Conclusions: MXF-22 showed a pronounced immunomodulatory effect contributing to the restoration of the function of CD4⁺ FoxP3⁺ T regs in acute pneumonia rat model.