Profiling the immune response to Mycobacterium tuberculosis Beijing family infection: a perspective from the transcriptome

Tuberculosis continues to be an important public health problem. Particularly considering Beijing-family strains of Mycobacterium tuberculosis, which have been associated with drug-resistance and hypervirulence. The Beijing-like SIT190 (BL) is the most prevalent Beijing strain in Colombia. The pathogenic mechanism and immune response against this pathogen is unknown. Thus, we compared the course of pulmonary TB in BALB/c mice infected with Classical-Beijing strain 391 and BL strain 323. The disease course was different among infected animals with Classical-Beijing and BL strain. Mice infected with BL had a 100% mortality at 45 days post-infection (dpi), with high bacillary loads and massive pneumonia, whereas infected animals with Classical-Beijing survived until 60 dpi and showed extensive pneumonia and necrosis. Lung RNA extraction was carried out at early (day 3 dpi), intermediate (day 14 dpi), and late (days 28 and 60 dpi) time points of infection. Transcriptional analysis of infected mice with Classical-Beijing showed several over-expressed genes, associated with a pro-inflammatory profile, including those for coding for CCL3 and CCL4 chemokines, both biomarkers of disease severity. Conversely, mice infected with BL displayed a profile which included the over-expression of several genes associated with immune-suppression, including Nkiras, Dleu2, and Sphk2, highlighting an anti-inflammatory milieu which would allow high bacterial replication followed by an intense inflammatory response. In summary, both Beijing strains induced a non-protective immune response which induced extensive tissue damage, BL strain induced rapidly extensive pneumonia and death, whereas Classical-Beijing strain produced slower extensive pneumonia later associated with extensive necrosis. Abbreviations Mtb: Mycobacterium tuberculosis; SIT: Spoligotype International Type; TB: Tuberculosis; CTB: Classical-typical Beijing; BL: Beijing-Like; CCL3: Chemokine (C-C motif) ligand 3 (CCL3); CCL4: Chemokine (C-C motif) ligand four (CCL4); WHO: World health Organization; DR: Direct Repeats; IFN-γ: Interferon Gamma; IL: Interleukin; TGF-β: Transforming Growth Factor Beta; XDR: Extremely Drug Resistant; MDR: Multi Drug Resistant; MIRU-VNTR: Mycobacterial Interspersed Repetitive Units–Variable Number Tandem repeats; OADC: Oleic Albumin Dextrose Catalase; ATCC: American Type Culture Collection; MOI: Multiplicity of Infection; CFUs: Colony Forming Units; ELISA: enzyme-linked immunosorbent assay; qRT-PCR: Real-Time Quantitative Reverse Transcription PCR; RNA-seq: Ribonucleic Acid sequencing; RIN: RNA Integrity Number; RNA: Ribonucleic Acid; DNA: Deoxyribonucleic Acid; dsDNA HS: Double stranded Deoxyribonucleic Acid High Sensitivity; RAI: Red de Apoyo à la Investigacion, Mexico City, Mexico; DEG: Differential Expressed Genes; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; ORA: Over-Representation Analysis; SNPs: Single Nucleotide Polymorphisms; TNFα: Tumoral necrosis factor alpha; DE: Differential Expression; EPA: Enrichment Pathways Analysis; TLR: Toll-Like receptor; NLRP: NOD-like receptor with Pyrin domain; tRNA: Transfer RNA; MAPK: Mitogen-Activated Protein Kinase; NK: Natural killer; ATP: Adenosine Triphosphate; DGC: dystrophin-glycoprotein complex; PDIM: Ptiocerol Dimicocerosate; NCBI: National Center for Bioinformatics Information