Abstract
Background: Tuberculosis (TB) is the second largest infectious disease killer in China, and the increasing prevalence of drug-resistant TB patients complicates treatment efforts and raises associated costs. Research on the mechanisms and characteristics of drug-resistant TB contributes to the discovery of new drug targets and the development of new anti-tuberculosis drugs. Methods: In this study, high-performance liquid chromatography (HPLC) was used to detect the content of polyamine metabolites, while western blotting, qPCR and ELISA were used to detect the expression of polyamine metabolism-related enzymes. The Oxford Nanopore Technologies (ONT) sequencing was applied to profile DNA methylation in multidrug-resistant Mycobacterium tuberculosis (Mtb). Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed on the screened differentially hypermethylated genes. Furthermore, STRING and Cytoscape software were used to construct a protein-protein interaction (PPI) network to identify the key genes. Results: The findings indicated the spermidine (SPD) and polyamine metabolism-related enzymes were elevated in the peripheral blood of TB patients. In addition, the production of polyamines and polyamine metabolism-related enzymes was increased in the peripheral blood of multidrug-resistant tuberculosis (MDR-TB) patients. GO and KEGG analyses showed that the differentially hypermethylated genes were mainly enriched in arginine metabolism. The PPI network analysis identified the top five key genes with the highest degrees: moaX, vapC49, vapB49, highA3 and nuoC. Conclusions: Polyamine metabolites were increased in the peripheral blood of MDR-TB patients. The differentially hypermethylated genes in multidrug-resistant Mtb are involved in the arginine biosynthetic process, the differentially methylated genes may play an important biological role in the multidrug resistance of Mtb.