Polybacterial immunomodulator Respivax restores the inductive function of innate immunity in patients with recurrent respiratory infections

Respivax (BulBio-NCIPD Ltd.) is an oral polybacterial immunomodulator intended for treatment and prevention of non-specific respiratory tract infections. We studied for the first time its effects on the inductive mechanisms of innate immunity, in the course of 3-month immunoprophylaxis of 25 patients with recurrent and chronic respiratory infections. The expression of pattern-recognition receptors on peripheral blood (PB) monocytes and plymorphonuclear cells (PMNs), the antigen-presenting and co-stimulatory potential of peripheral blood monocytes and dendritic cells; and the stimulated Th1/Th2 cytokine production were determined by flow cytometry. As compared to healthy controls, patients were characterized with down-regulation of TLR2 and TLR4/CD14 complex on PB monocytes (p < 0.01), decreased share of CD14+CD16+ DCs precursors (p < 0.01), decreased CD86 expression on PB DCs (p < 0.05) and a Th2 shift of cytokine profile. Respivax modulated differentially the surface expression of pattern-recognition receptors on PB monocytes, increasing TLR2 and CD14 without affecting TLR4 expression. Further on, Respivax enhanced the differentiation of mature CD86high dendritic cells (DCs). Importantly, Respivax promoted a Th1 shift of cytokine profile and restored the Th1/Th2 cytokine balance without pro-inflammatory effects. Noteworthy, Th1/Th2 ratios in the patient's group correlated positively with the levels of TLR2 (R = 0.5, p < 0.001) and CD14 expression (R = 0.4, p < 0.05). We conclude that Respivax treatment restores the inductive function of innate immunity at three key levels: antigen recognition and presentation, co-stimulation of naïve T cells, and Th1/Th2 balance. This results, at least in part, from a differential modulation effect on the expression of pathogen-recognition receptors.