PHYSICO-CHEMISTRY, PROTEOMICS AND IN VIVO COMPARATIVE TESTS TO REVEAL VARIABILITY IN MULTISTRAIN PROBIOTIC FORMULATIONS

VSL#3 powder formulations originated from two production sites (USA- and ITALY-made products) were subjected to a physicochemical characterization based on thermal and colloidal properties [1], proteomics analyses, and in vivointestinal permeability tests on animal models. Thermogravimetry-Differential Scanning Calorimetry (TGA-DSC) analyses provided powder sample profiles in mass and internal energy changes under temperature scan, and thermophysical data in terms of material decomposition and transition phases. Sample particle sizes, size distributions, and charges at the dispersed state informed on their capacity to remain stable in aqueous suspension. Table 1 compares physicochemical data generated from USA- and ITALY-made formulations obtained with different lots (lots DM538 and 10151198 analyzed after 0 and 3 months for USA vs.lots 512058 and 3302E10 analyzed after 0 and 3 months for ITALY). Even though both formulations were qualitatively similar in thermal and colloidal profiles, significant differences were quantitatively observed in terms of maximum decomposition temperature Tmax (p< 0.05), and transition phase temperature Tm (p < 0.01), as illustrated in Figure 1. Further comparative analyses by proteomics showed 99 proteins decreased abundances and 38 increased ones in ITALY-made batch (lot 512058) compared to the US-made one (lot DM538), and revealed differences in protein identities and origins. In vivo intestinal permeability tests with old mice confirmed such significant differences between US-made lot DM538 and IT-made lot 512058. In conclusion, the thermal scan data and shotgun proteomic comparisons demonstrate significant physicochemical and chemical variability between multistrain probiotic VSL#3 formulations from two manufacturer countries. Such differences have an impact on the intestinal permeability in vivo.

[1] Razafindralambo, H. et al. (2019). Physico-chemical Approach for Characterizing Probiotics at the Solid and Dispersed States. Food Research International, 2019, vol.116-897-904