The immunomodulatory effects of Mesenchymal stem cells on THP-1-derived macrophages against Mycobacterium tuberculosis H37Ra infection.

Background: Immune imbalance is crucial in tuberculosis pathogenesis and may be modulated by mesenchymal stem cells (MSCs). However, how MSCs regulate the host's response to Mycobacterium tuberculosis (Mtb) is unclear.

Methods: Human umbilical cord-derived MSCs were co-cultured with Mtb-infected THP-1 macrophages. The intracellular release of ROS in macrophages was measured by DCFH-DA. Cytokine expression was measured by RT-qPCR, apoptosis by Annexin V/PI assay, and pyroptosis markers by Western blotting. Differentially expressed genes (DEGs) in Mtb-infected THP-1 co-cultured with or without MSCs were identified by RNA-seq and potential signaling pathways were analyzed through bioinformatics.

Results: The fibroblastic morphology of MSCs exhibited 95 % positivity for CD73, CD90, and CD105, while the positivity rate for negative marker HLA-DR was less than 2 %. In Mtb-infected THP-1 macrophages, co-culturing with MSCs increased ROS release, cytokines expression (IL-1β, IL-6, TNF-α), apoptosis, and pyroptosis markers (NLRP3, Caspase-1, and GSDMD). Comparative transcriptome analysis identified 347 up-regulated and 291 down-regulated DEGs, primarily associated with receptor-ligand interactions and enriched in cytokine signaling pathways including JAK-STAT, TNF, ferroptosis, and autophagy.

Conclusion: MSCs could enhance the macrophages' immune response to Mtb by activating immune receptors and inflammatory signaling pathways.