Modern Beijing sublineage of Mycobacterium tuberculosis shift macrophage into a hyperinflammatory status

Clinical Features and Predictors of Treatment Outcome in Patients with Ocular Tuberculosis from the Netherlands and Indonesia: The OculaR TB in Low versus High Endemic Countries (ORTEC) Study

PURPOSE

To describe and compare clinical features, treatment approaches, and treatment outcomes of ocular tuberculosis (OTB) patients in the Netherlands, a low tuberculosis (TB)-endemic country, and Indonesia, a high TB-endemic country. We also aimed to identify predictors of treatment outcomes.

METHODS

A medical chart review of 339 OTB patients (n = 93 from the Netherlands and n = 246 from Indonesia) was performed. The primary outcome was response to treatment, whether with or without anti-tubercular treatment, after six months of treatment initiation (good versus poor responders).

RESULTS

Indonesian OTB patients displayed a higher prevalence of chest radiograph findings indicative of TB infection (p < 0.001) and concurrent active systemic TB (p = 0.011). Indonesian cohort exhibited a more acute and severe disease profile, including uveitis duration ≤ 3 months (p < 0.001), blindness (p < 0.001), anterior chamber (AC) cells ≥ 2+ (p < 0.001), and posterior synechiae (p < 0.001). Overall proportions of good responders to treatment were 67.6% in the Netherlands and 71.5% in Indonesia. Presence of AC cell ≥ 2+ (adjusted odds ratio (aOR): 2.12, 95% CI: 1.09-4.14), choroidal lesions other than serpiginous-like choroiditis (SLC) or tuberculoma (aOR: 4.47, 95% CI: 1.18-16.90), and retinal vasculitis (aOR: 2.32, 95% CI: 1.10-4.90) at baseline were predictors for poor response to treatment.

CONCLUSIONS

Despite a more severe initial clinical presentation in the Indonesian cohort, the overall treatment outcomes of OTB was comparable in both cohorts. Three baseline clinical features were identified as predictors of treatment outcomes.

Significance of genotypes and resistance status of Mycobacterium tuberculosis strains in gene expression of apoptosis cell death and inflammatory pathways in A549 lung epithelial cell line

Objectives

Tuberculosis (TB) has been a major health issue throughout history. As part of TB infection, host-Mycobacterium tuberculosis (Mtb) interactions are important. Through immune pathology and cell death control processes, Mtb infection facilitates intracellular growth. The relationship between apoptosis and inflammation in Mtb infection remains unclear. In this study, the levels of related apoptosis and inflammatory genes were assessed in A549 cells infected with a variety of Mtb strains.

Materials and Methods

Mtb isolates with different phenotypes (sensitive, INHR, RifR, MDR, and XDR) were collected from the Pasteur Institute of Iran, during this study. Whole genome sequencing was previously performed on all strains, and the Beijing genotype was selected as sensitive. Also, for other resistant strains, the New-1 genotype was available and isolated for genotype comparison. A549 lung carcinoma cells were also grown and infected with selected Mtb strains. Genes involved in inflammation and apoptosis were detected using reverse transcription-PCR (RT-PCR).

Results

All sensitive strains and resistant strains were found to significantly up-regulate anti-apoptotic (bcl2 and rb1), chemokine (IL-8 and MCP-1), and pro-inflammatory cytokine (TNF-α and IFN-γ) expression, while significant down-regulation was observed after 24 and 48 hr of infection in anti-inflammatory genes (IL-10) and pro-apoptotic genes (bad and bax). Besides resistance strains, Mtb genotypes also affected gene expression. The Beijing genotype (sensitive isolate) influences inflammatory and apoptotic genes more sharply than the New-1 genotype (INHR, RifR, MDR, and XDR).

Conclusion

Gene expression differences related to apoptosis and inflammation examined in the current study may be attributed to genotypes rather than resistance status since the expression of most genes has been observed to be lower in resistant strains (INHR, RifR, MDR, and XDR belonging to the New-1 genotype) compared to sensitive strains (Beijing genotype).

Mycobacterium tuberculosis complex molecular networks and their regulation: Implications of strain heterogeneity on epigenetic diversity and transcriptome regulation

Tuberculosis has been a public health crisis since the 1900, which has caused the highest mortalities due to a single bacterial infection worldwide, that was recently further complicated by the Coronavirus disease 2019 pandemic. The causative agent of Tuberculosis, Mycobacterium tuberculosis, belongs to a genetically well-characterized family of strains known as the Mycobacterium tuberculosis complex, which has complicated progress made towards eradicating Tuberculosis due to pathogen-specific phenotypic differences in the members of this complex. Mycobacterium tuberculosis complex strains are genetically diverse human- and animal-adapted pathogens belonging to 7 lineages (Indo-Oceanic, East-Asian, East-African Indian, Euro-American, M. africanum West Africa 1, M. africanum West Africa 2 and Ethopia), respectively and the recently identified Lineage 8 and M. africanum Lineage 9. Genomic studies have revealed that Mycobacterium tuberculosis complex members are ∼99 % similar, however, due to selective pressure and adaptation to human host, they are prone to mutations that have resulted in development of drug resistance and phenotypic heterogeneity that impact strain virulence. Furthermore, members of the Mycobacterium tuberculosis complex have preferred geographic locations and possess unique phenotypic characteristics that is linked to their pathogenicity. Due to the recent advances in development next generation sequencing platforms, several studies have revealed epigenetic changes in genomic regions combined with "unique" gene regulatory mechanisms through non-coding RNAs that are responsible for strain-specific behaviour on in vitro and in vivo infection models. The current review provides up to date epigenetic patterns, gene regulation through non-coding RNAs, together with implications of these mechanisms in down-stream proteome and metabolome, which may be responsible for "unique" responses to infection by members of the Mycobacterium tuberculosis complex. Understanding lineage-specific molecular mechanisms during infection may provide novel drug targets and disease control measures towards World Health organization END-TB strategy.

The Global Success of Mycobacterium tuberculosis Modern Beijing Family Is Driven by a Few Recently Emerged Strains

Strains of the Mycobacterium tuberculosis complex (MTBC) Beijing family aroused concern because they were often found in clusters and appeared to be exceptionally transmissible. However, it was later found that strains of the Beijing family were heterogeneous, and the transmission advantage was restricted to sublineage L2.3 or modern Beijing. In this study, we analyzed the previously published genome sequences of 7,896 L2.3 strains from 51 different countries. Using BEAST software to approximate the temporal emergence of L2.3, our calculations suggest that L2.3 initially emerged in northern East Asia during the early 15th century and subsequently diverged into six phylogenetic clades, identified as L2.3.1 through L2.3.6. Using terminal branch length and genomic clustering as proxies for transmissibility, we found that the six clades displayed distinct population dynamics, with the three recently emerged clades (L2.3.4 to L2.3.6) exhibiting significantly higher transmissibility than the older three clades (L2.3.1 to L2.3.3). Of the Beijing family strains isolated outside East Asia, 83.1% belonged to the clades L2.3.4 to L2.3.6, which were also associated with more cross-border transmission. This work reveals the heterogeneity in sublineage L2.3 and demonstrates that the global success of Beijing family strains is driven by the three recently emerged L2.3 clades. IMPORTANCE The recent population dynamics of the global tuberculosis epidemic are heavily shaped by Mycobacterium tuberculosis complex (MTBC) strains with enhanced transmissibility. The infamous Beijing family strain stands out because it has rapidly spread throughout the world. Identifying the strains responsible for the global expansion and tracing their evolution should help to understand the nature of high transmissibility and develop effective strategies to control transmission. In this study, we found that the L2.3 sublineage diversified into six phylogenetic clades (L2.3.1 to L2.3.6) with various transmission characteristics. Clades L2.3.4 to L2.3.6 exhibited significantly higher transmissibility than clades L2.3.1 to L2.3.3, which helps explain why more than 80% of Beijing family strains collected outside East Asia belong to these three clades. We conclude that the global success of L2.3 was not caused by the entire L2.3 sublineage but rather was due to the rapid expansion of L2.3.4 to L2.3.6. Tracking the transmission of L2.3.4 to L2.3.6 strains can help to formulate targeted TB prevention and control.

Transcriptomic Analysis of Mycobacterial Infected Macrophages Reveals a High MOI Specific Type I IFN Signaling

Macrophage (MΦ) infection models are important tools for studying host-mycobacterial interactions. Although the multiplicity of infection (MOI) is an important experimental variable, the selection of MOI in mycobacterial infection experiments is largely empirical, without reference to solid experimental data. To provide relevant data, we used RNA-seq to analyze the gene expression profiles of MΦs 4 or 24 h after infection with Mycobacterium marinum (M. m) at MOIs ranging from 0.1 to 50. Analysis of differentially expressed genes (DEGs) showed that different MOIs are linked to distinct transcriptomic changes and only 10% of DEGs were shared by MΦ infected at all MOIs. KEGG pathway enrichment analysis revealed that type I interferon (IFN)-related pathways were inoculant dose-dependent and enriched only at high MOIs, whereas TNF pathways were inoculant dose-independent and enriched at all MOIs. Protein-protein interaction (PPI) network alignment showed that different MOIs had distinct key node genes. By fluorescence-activated cell sorting and follow-up RT-PCR analysis, we could separate infected MΦs from uninfected MΦs and found phagocytosis of mycobacteria to be the determinant factor for type I IFN production. The distinct transcriptional regulation of RAW264.7 MΦ genes at different MOIs was also seen with Mycobacterium tuberculosis (M.tb) infections and primary MΦ infection models. In summary, transcriptional profiling of mycobacterial infected MΦs revealed that different MOIs activate distinct immune pathways and the type I IFN pathway is activated only at high MOIs. This study should provide guidance for selecting the MOI most appropriate for different research questions.

Clinical isolates of Mycobacterium tuberculosis with different genotypes exhibit distinct host macrophage responses in vitro

Introduction. Mycobacterium tuberculosis (M.tb), the causative agent of tuberculosis, can survive as an intracellular parasite after entering macrophages via phagocytosis. M.tb strains are genotypically distinct and engage in diverse pathogen-host interactions, with different host immune responses triggered by different M.tb strains. Importantly, differences in intracellular accumulation and triggering of host macrophage responses during early infection stages are key determinants that shape the final outcomes of host innate immune responses to different M.tb strains.Hypothesis/Gap Statement. Clinical M.tb strains with different genotypes elicit different host innate immune responses in vitro.Aim. This work aimed to compare host innate immune responses elicited by genotypically diverse, clinically derived M.tb strains in vitro.Methodology. RAW264.7 cells were infected with three lineage 2 and lineage 4 clinically derived M.tb strains and strain H37Rv. Strains were evaluated for differences in intracellular growth, induction of macrophage apoptosis, and induction of expression of proinflammatory cytokines and associated pattern recognition receptors.Results. Highly variable cytokine profiles were observed subsequent to RAW264.7 cell infection with the different strains. The Beijing genotype strain, a modern Beijing strain belonging to lineage 2, induced milder host proinflammatory responses and less apoptosis and exhibited greater intracellular growth as compared to the other strains. Moreover, mRNA expression levels of iNOS in Beijing and MANU2 genotype strains exceeded corresponding levels obtained for the T1 genotype strain. Meanwhile, mRNA expression levels of toll-like receptor (TLR)-encoding genes TLR2 and TLR7 in macrophages infected with the Beijing genotype strain were higher than corresponding levels observed in MANU2 genotype strain-infected macrophages.Conclusion. The higher intracellular survival rate and lower level of host cell apoptosis associated with macrophage infection with the Beijing genotype strain indicated greater virulence of this strain relative to that of the other strains. Furthermore, in vitro immune responses induced by the Beijing genotype strain were unique in that this strain induced a weaker inflammatory response than was induced by T1 or MANU2 genotype strains. Nevertheless, additional evidence is needed to confirm that Beijing genotype strains possess greater virulence than strains with other genotypes.