Extracellular Proteins Isolated from L. acidophilus as an Osteomicrobiological Therapeutic Agent to Reduce Pathogenic Biofilm Formation, Regulate Chronic Inflammation, and Augment Bone Formation In Vitro.

Periprosthetic joint infection (PJI) is a challenging complication that can occur following joint replacement surgery. Efficacious strategies to prevent and treat PJI and its recurrence remain elusive, and a novel resolution is urgently needed. Commensal bacteria within the gut microbiota convey beneficial effects by contributing to a defense strategy named "colonization resistance" thereby preventing pathogenic infection and overgrowth along the intestinal surface. This blueprint may be applicable to PJI. Here, the aim was to investigate Lactobacillus acidophilus spp. and primarily, isolated extracellular-derived L. acidophilus proteins (LaEPs) on PJI relevant S. aureus, MRSA, and E. coli planktonic growth and biofilm formation in vitro. The effect of LaEPs on cultured RAW264.7 macrophages and osteogenic, and adipogenic hBMSC differentiation was also analyzed. Data show electrostatically-induced probiotic-pathogen species co-aggregation and pathogenic growth inhibition together with LaEP-induced biofilm prevention. LaEPs activated macrophages priming them for enhanced microbial phagocytosis via cathepsin K, reduced lipopolysaccharide-induced DNA damage and RANKL expression, and promoted a reparative M2 macrophage morphology when under chronic inflammatory conditions. Our data also show LaEPs significantly augmented bone deposition while abating adipogenesis thus holding promise as a potential multimodal therapeutic strategy. Proteomic analyses highlight high abundance of lysyl endopeptidase, urocanate reductase, uridylate kinase, large ribosomal subunit protein bL12, and polyketide synthase. Further in vivo analyses are warranted to elucidate their role in the prevention and treatment of PJIs. This article is protected by copyright. All rights reserved.