Abstract: Objective To analyze the differences in peripheral blood transcriptomics and immune infiltration characteristics between multidrug-resistant tuberculosis (MDR-TB) and drug-susceptible tuberculosis (DS-TB) patients, explore the correlation between differential gene expression levels and immune cell proportions, and provide evidence for elucidating the pathogenesis of MDR-TB. Method This cross-sectional study enrolled 10 pulmonary tuberculosis patients who admitted to Sixth People's Hospital of Xinjiang Uygur Autonomous Region from January to December 2024. Based on molecular drug sensitivity results, they were divided into a multidrug-resistant group and a drug-sensitive group. Venous whole blood samples were collected from each patients, and RNA was extracted for high-throughput sequencing. Differentially expressed genes in the two groups were identified through mRNA transcriptomics analysis. The gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases were used to perform functional annotation and pathway enrichment analysis on the differentially expressed genes to clarify their associated functions and core enriched pathways. The immune cell composition of the patients was calculated using the quantexq algorithm, and the differences in immune cell percentage between the two groups were compared. Immune-related differentially expressed genes were selected, and Spearman correlation analysis was used to calculate the correlation between these genes and the immune cell percentages. Result Using drug-sensitive pulmonary tuberculosis patients as the control and based on the predefined screening thresholds for differentially expressed genes, a total of 583 differentially expressed genes were identified in multidrug-resistant pulmonary tuberculosis patients, including 330 upregulated genes and 253 downregulated genes. Among the 10 immune cell types, the percentage of neutrophils in multidrug-resistant group was significantly higher than that in drug-sensitive tuberculosis group (P<0.05). The expression levels of seven immune-related differentially expressed genes showed a strong correlation with the percentage of neutrophils (|R|>0.5), with MAP1LC3A and CASP5 showing the strongest correlation. Specifically, the expression level of MAP1LC3A was negatively correlated with the proportion of neutrophils (R=-0.527, P=0.117), while the expression level of CASP5 was positively correlated with the proportion of neutrophils (R=0.661, P=0.038). Conclusion Compared with drug-sensitive patients, multidrug-resistant tuberculosis patients had a significantly increased percentage of peripheral blood neutrophils. Downregulation of MAP1LC3A and upregulation of CASP5 in the peripheral blood of multidrug-resistant tuberculosis patients were highly correlated with the increased percentage of neutrophils.The autophagy mechanism mediated by MAP1LC3A and the abnormal neutrophil extracellular traps generation and inflammatory response mainly based on CASP5 were important breakthroughs for in-depth research into the drug resistance mechanism of pulmonary tuberculosis.

Key words: Pulmonary tuberculosis, Multidrug-resistant, Transcriptomics, Immune microenvironment