Beneficial immune-regulatory effects of novel strains of Aureobasidium pullulans AFO-202 and N-163 produced beta glucans in Sprague Dawley rats

Background:Immune system dysregulation plays a significant role in the pathogenesis of COVID-19. A balanced immune response is essential to mounting anti-viral defences, and biomarkers such as the white blood cell (WBC) count, the neutrophil-to-lymphocyte ratio (NLR) and the lymphocyte-to-C-reactive-protein (LCR) ratio have been reported as potential predictors of immune status. The beneficial immunomodulation effects of a biological response modifier glucan (BRMG) produced by two strains of Aureobasidium pullulans, AFO-202 and N-163, were reported in earlier in vitro studies. In this study, we compared their efficacy on immune-inflammatory parameters in Sprague Dawley (SD) rats.Methods:This study was performed on four groups of healthy SD rats, with six subjects in each group: Group 1, which was euthanised on Day 0 to obtain baseline values; Group 2, which served as the control (drinking water); Group 3, which received AFO-202 beta glucan at a dose of 200 mg/kg/day; and Group 4, which received N-163 beta glucan at a dose of 300 mg/kg/day. Test solutions were administered to the animals in Groups 2–4 by gavage once daily for 28 consecutive days. Biochemical analyses were conducted on haematological, immunological and inflammatory biomarkers on Days 15 and 29.Results:The NLR decreased, whereas the LCR and leukocyte-to-C-reactive protein ratio (LeCR) increased in Group 3 (AFO-202) at 15 days, but the values were within the normal physiological range only. At 29 days, this difference among the groups was not observed. There were no significant differences between the groups in the other parameters, such as red blood cell (RBC) count, WBC count, CRP, IgA, IL-6, IFN-γ and sFAS.Conclusion:AFO-202 beta glucan helps marginally decrease NLR and increase LCR and LeCR in healthy SD rats within 15 days. This might be beneficial to tackling infections such as COVID-19 that involve immune system dysregulation. These results warrant further investigations in larger numbers of healthy and diseased models to develop appropriate strategies for balancing immune system dysregulation using these beta glucan food supplements with proven safety.