Safety Assessment of Potential Probiotic Lactobacillus fermentum MTCC-5898 in Murine Model after Repetitive Dose for 28 Days (Sub-Acute Exposure)

Safety assessment of probiotic Lactobacillus fermentum MTCC-5898 (LF) with three doses (10⁷, 10⁹, and 10¹¹ cfu/day/animal) was carried on Swiss albino mouse weanlings for 28 days using oral route. Health status of animals was monitored by physical assessment of body weight, organ indices, and histological appearances of liver and intestine along with measurement of hematological parameters (Hb, WBC, RBC count, MCHC, MCV, MCH), biochemical analytes in blood involving glucose, serum enzymes (ALT, AST and LDH), urea, creatinine, and lipid profile (total cholesterol, triglycerides, HDL, VLDL, LDL, and atherogenic index). LF showed no adverse effects on above parameters of general health status after continuous consumption for the experimental period. On the other hand, significant increase (p ≤ 0.05) in TGF-β (regulatory cytokine) and considerable decrease (p ≤ 0.05) in IFN-γ (pro-inflammatory cytokine) without any major changes in IL-4 and IL-12 in intestinal fluid on consumption of 10⁹ cfu/animal/day confirmed its dose-specific response for immune homeostasis. Further, safety of LF was also confirmed by insignificant changes in release of FITC-dextran (4 kDa) in blood on its consumption than control group where only saline was given orally. Moreover, significantly (p ≤ 0.05) increased mRNA expression of claudin-1 and MUC-2 in intestinal epithelial cells on feeding L. fermentum further supported FITC-dextran permeability data which otherwise showed increased flux of FITC-dextran in blood on consumption of E. coli (10⁹ cfu/animal/day) due to intestinal damage. Thus, in vivo results confirmed that Lactobacillus fermentum MTCC 5898 is safe and non-toxic to weanling mice and may be considered for functional food application after clinical testing.