Liubao tea as a functional fermented food: multi-omics insights into its modulation of lymphatic endothelial cell...

The "metabolism-inflammation" vicious cycle is an important driving factor for lymphatic dysfunction in secondary lymphedema (SL). Among them, lymph endothelial cells (LECs) act as a key regulatory hub. Liubao tea (LBT), a traditional post-fermented black tea, has anti-inflammatory, anti-fibrotic and lipid-lowering effects. However, whether the effects of LBT can extend to the lymphatic system, especially whether it functions by regulating the metabolism and immune function of LECs, still needs further clarification.

This study combined single-cell transcriptomics, bulk transcriptomics, network pharmacology, and molecular docking to systematically identify potential genes related to LBT in LECs. Subsequently, the effects of the LBT extract on the functions of human lymphatic endothelial cells (HLECs) and the expression of target genes were verified using the Cell Counting Kit-8 (CCK-8), wound healing experiments, and real-time quantitative polymerase chain reaction (RT-qPCR).

The single-cell analysis revealed that the proportion of endothelial cells (ECs) in SL was significantly reduced (from 1.09% to 0.54%), but the expression of protein kinase Cβ (PRKCB) in the ECs showed a significant increase [fold change (FC) = 24.30, log₂FC = 4.60, p = 1.44 × 10^-7], and the positive rate increased from <1% to 12%. Multigene integration analysis revealed that PRKCB was the only gene that overlapped among all the differentially expressed genes (DEGs) in large-scale transcriptomes, the DEGs specific to ECs, and the predicted targets of LBT. Protein-protein interaction (PPI) network analysis revealed that PRKCB interacts with the nuclear factor κB kinase inhibitor β subunit (IKBKB), the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit γ (PIK3CG), and glycogen synthase kinase 3β (GSK3B). Molecular docking results indicated that multiple LBT components (especially tirilose) have a strong affinity for PRKCB (minimum binding energy: -9.3 kcal/mole). In vitro experiments demonstrated that the extract of LBT (50 μg/ml) significantly reversed the decline in the survival rate and migration ability of HLECs caused by lipopolysaccharide (LPS; p < 0.01 and p < 0.001), and downregulated the mRNA expression of PRKCB (p < 0.05), and upregulated the mRNA expression of PROX1 (p < 0.05).

This study reveals that LBT may ameliorate LEC dysfunction in lymphedema by targeting PRKCB to disrupt the bidirectional "inflammation-metabolism" vicious cycle. These findings provide a scientific basis for the use of LBT as a functional fermented food in lymphedema intervention and open new avenues for targeting PRKCB with natural products in the treatment of inflammation-related lymphatic diseases.