Lactobacillus rhamnosus(LR)

Triple-negative breast cancer (TNBC) is an aggressive breast cancer (BC) subtype with limited benefit from immune checkpoint blockade (ICB) and frequent immune-related adverse events (irAEs). We achieved stable overexpression of PD-1 in tumor cells through intratumoral injection of a PD-1-overexpressing plasmid. The results indicated that intratumoral PD-1 gene therapy exerted a dual effect. It significantly inhibited tumor cell growth via PD-1/PD-L1 interaction. Moreover, it promoted antitumor immunity, as evidenced by increased CD8⁺ T cells in the spleen, mesenteric lymph nodes (MLNs), and tumor tissues. Nevertheless, intratumoral PD-1 gene therapy induced intestinal side effects. Importantly, the probiotic Lactobacillus rhamnosus (L. rhamnosus) not only enhanced the antitumor activity of intratumoral PD-1 gene therapy but also alleviated intestinal injury. L. rhamnosus increased the expression of tight junction proteins (TJPs), including Claudin-1, Occludin, and ZO-1, upregulated anti-inflammatory cytokines (IL-10, TGF-β) and downregulated pro-inflammatory cytokines (IL-6, TNF-α). Notably, L. rhamnosus treatment also favorably reshaped the gut microbial composition, increasing the abundance of beneficial bacteria such as Lactobacillus, Bacteroides, and Parabacteroides, while reducing the levels of potential pathogenic bacteria including Prevotella, Staphylococcus, Adlercreutzia, and Desulfovibrio. Furthermore, metabolomic analysis revealed that L.rhamnosus significantly influenced tyrosine metabolism-related metabolites, downregulating the abundance of L-tyrosine, 3,4-dihydroxyphenylalanine (DOPA), N-acetyltyramine, methionyl-tyrosine, glutamic acid, and valine, while upregulating the level of butanoic acid. Collectively, these findings provide novel therapeutic strategies for enhancing the efficacy of TNBC treatment and alleviating intestinal side effects associated with immunotherapy.

The rise in free radical species and bacterial infections accelerates biofilm formation, impeding wound healing and leading to severe complications, thereby posing a significant global threat to public health. In this study, we synthesized a novel nanobiohybrid material by coating maghemite nanoparticles (γ-Fe₂O₃ NPs) onto the surface of Lactobacillus rhamnosus (LR) probiotics to address bacterial infections, inhibit biofilm formation, and scavenge free radicals. The γ-Fe₂O₃ NPs-LR nanobiohybrid was characterized using PXRD, FTIR, XPS, TEM, FESEM, zeta potential analysis, and UV-Vis spectroscopy, confirming the successful interaction between the γ-Fe₂O₃ NPs and LR. The antibacterial activity of the nanobiohybrid at 1000 μg mL^-1 was assessed by measuring the zone of inhibition against L. monocytogenes (15.17 ± 0.29 mm), S. succinus (12.83 ± 0.29 mm), S. thompson (5.33 ± 0.29 mm), and E. coli O157:H7 (7.67 ± 0.29 mm), revealing significantly higher inhibitory effects compared to γ-Fe₂O₃ NPs and LR alone. Antibiofilm assays demonstrated the nanobiohybrid's superior ability to inhibit and disrupt established biofilms. Additionally, the antioxidant potential was evaluated using the DPPH scavenging assay, which showed enhanced scavenging activity (66.57 ± 0.53% at 500 µg mL^-1). Importantly, cytotoxicity studies on mouse embryonic fibroblast (MEF) and human intestinal (Caco-2) cell lines confirmed that the nanobiohybrid exhibits excellent biocompatibility at relevant concentrations. This study demonstrates that the γ-Fe₂O₃ NPs-LR nanobiohybrid is a promising biocompatible synergistic platform for diverse biomedical applications, including infection control, wound healing, and oxidative stress management.