Spore probiotic modulates lung inflammation triggered by theviral pathogen-associated molecular pattern poly (I:C) in BALB/c mice.

Background and Aim : Several viral pathogens including SARS CoV ۲ are associated with thelung inflammation. The severity of disease is associated with the production of a cytokine storm(CS) by the macrophages inside the host cell post-viral attack. Since the cytokine storm is the lifethreateningthrough the elevated levels of circulating cytokines, factors targeting these proinflammatoryproteins may be an ideal strategy for the management of various inflammatorydisorders like coronavirus disease. In this study, the intranasal administration of spore probioticwas investigated to modulate the lung inflammatory response of Balb/c mice triggered by the viralpathogen-associated molecular pattern polyinosinic acid-polycytidylic acid (poly (I:C)).Methods : Male BALB/c (approximately ۲۰ g, ۸–۱۲ weeks old) were obtained from the RaziInstitute (Mashhad, Iran) and housed in a conventional animal house with ۱۲-hours dark/lightcycles. Water and pelleted food were provided ad libitum. The animals were anesthetized byisoflurane inhalation and ۲۰ μl of heat-inactivated spore probiotic cells (۱۰⁸ CFU/mL) wereadministered intranasally for ۵ consecutive days. On days ۵-۷ mice received three doses of ۲۰ μlpoly (I:C) (۱ mg/ml). Mice were euthanized on day ۱۰ i.e. ۲۴ h after the last intranasal treatment.Control animals received PBS instead of bacterial suspensions. Inflammatory modulatory activityof spore probiotic was determined based on bronchoalveolar tissue lavage (BALF) cytokines, lunghistology, and the lung wet-to-dry (W/D) weight ratio.Results : Pro-inflammatory cytokines including TNF-?, IL-۱? and IL-۶ were reduced ۲.۵, ۱.۸, and۱۴.۵ folds while the anti-inflammatory cytokines i.e. TGF-? and IL-۱۰ were increased ۱.۰۶ and۲.۲ folds in the mice received spore probiotic, respectively. Compared with the control group(۶.۷?±?۰.۱۵), the wet/dry weight ratios of lung tissues in the probiotic group (۵.۷۵?±?۰.۱۲) weresignificantly decreased(p<۰.۰۵).The effect of probiotic treatment on lung pathology was revealedthat lung injury and the number of mononuclear cells were significantly reduced in animals treatedwith probiotic(p<۰.۰۵).Conclusion : Spore probiotics are probably promising agents to modulate life-threatinginflammation associated with viral infections like SARS CoV ۲.