New findings of Toll-like receptors involved in Mycobacterium tuberculosis infection

Effects of calcitriol on oxidative burst, phagocytic function, and leukocyte cytokine production in shelter dogs

Background

The active metabolite of vitamin D, calcitriol, has been shown across many different species to augment innate immune responses and dampen aberrant proinflammatory cytokine production. Community acquired infections are common in shelters and consume limited shelter resources, impact adoption rates, and can result in unnecessary euthanasia. Prophylactic oral vitamin D supplementation decreases the incidence and severity of upper and lower respiratory tract infections in humans. Before a clinical trial investigating the clinical benefit of oral vitamin D supplementation in shelter dogs can be pursued, an in vitro study evaluating the immunomodulatory effects of calcitriol in blood from shelter dogs is warranted. Therefore, the objective of this study was to determine if incubation of whole blood obtained from apparently healthy dogs housed in a shelter for ≥7 days with calcitriol would alter granulocyte/monocyte (GM) oxidative burst and phagocytic function as well as pathogen-associated molecular pattern (PAMP)-stimulated leukocyte production of tumor necrosis factor (TNF)-α, and interleukin (IL)-6, and IL-10.

Results

Ten dogs housed in a shelter for ≥7 days were enrolled in a prospective cohort study. Whole blood from these dogs was incubated with calcitriol (10^− 7 M) or diluent (control) for 24 h. Subsequent to this incubation, phagocytosis of opsonized-Escherichia coli (E. coli) and E. coli-induced oxidative burst were evaluated via flow cytometry. In addition, leukocyte production of TNF-α, IL-6, and IL-10 were measured using a canine-specific multiplex bead assay. Calcitriol significantly decreased leukocyte TNF-α production (p = 0.009) and increased IL-10 production (p = 0.002). Tumor necrosis factor-α-to-IL-10 ratio was significantly decreased with calcitriol (p = 0.017), while IL-6 production as well as GM oxidative burst and phagocytic function were not significantly affected.

Conclusions

These data indicate that calcitriol attenuates proinflammatory immune responses without affecting GM oxidative burst or phagocytic function in vitro in whole blood obtained from apparently healthy shelter dogs.

Toll-like receptor 4 polymorphisms were associated with low serum pro-inflammatory cytokines in BCG osteitis survivors

AIM

The aim of the study was to evaluate the association of Toll-like receptor 4 (TLR4) gene variations with osteitis risk after Bacillus Calmette-Guérin (BCG) vaccination given at birth and with serum cytokine levels measured in adulthood.

METHODS

We determined the TLR4 rs4986790 single-nucleotide polymorphism (SNP) in 132 study subjects with BCG osteitis in infancy and compared the genotype distributions and allele frequencies between them and population controls. Serum concentrations of 11 cytokines measured in adulthood were compared between study subjects with the wild vs variant TLR4 rs4986790 genotype.

RESULTS

The genotypes and allele frequencies of the TLR4 rs4986790 SNP did not differ between BCG osteitis cases and population controls. Instead, subjects with the variant genotype presented with lower serum interleukin (IL) concentrations of the pro-inflammatory IL-6, IL-17A and IL-12 cytokines and with marginally lower interferon-γ concentrations, but with higher serum anti-inflammatory IL-4 concentration. The results concern also the TLR4 rs4986791, since these two SNPs are co-segregating in the Finnish population.

CONCLUSION

The findings suggest that TLR4 has no significant role in the emergence of osteitis after newborn BCG vaccination, but the variant genotypes of the TLR4 rs4986790 and rs4986791 may impair the production of pro-inflammatory cytokines.

Pathologic characteristics of spinal tuberculosis: analysis of 181 cases

OBJECTIVE

This study aimed to provide a basis for the diagnosis of spinal TB by analyzing its pathologic characteristics.

METHODS

The data of 181 patients with spinal TB who underwent surgery from January 2013 to January 2019 at the General Hospital of Ningxia Medical University were retrospectively analyzed. The participants comprised 80 men and 101 women with an average age of 45.1 ± 16.5 (range: 14-78) years. Based on the assessment of tissue samples, five patients had cervical TB, 49 had thoracic TB, 86 had lumbar TB, 22 had thoracolumbar TB, and 19 had lumbosacral TB. Tuberculous granulation tissue, sclerotic bone, sequestrum, and intervertebral disc tissue were collected for hematoxylin and eosin staining. The proportion of patients with atypical and typical pathologic characteristics was identified and compared for statistical analysis.

RESULTS

The typical pathologic characteristics included tubercles, granulomas, caseous necrosis, multinuclear giant cells, infiltration of acute inflammatory cells, sequestration, and fibroblastic proliferation. A total of 119 patients had caseous necrosis, 95 had multinuclear giant cells, 68 had granulomatous inflammation, and 21 had tubercles. Moreover, 46 (25.4%) patients had at least three pathologic characteristics and only 12 (6.6%) exhibited all the pathologic characteristics. Of the 35 (19.3%) patients with atypical pathologic characteristics, 17 had lymphocyte infiltration, 10 had fibroblastic proliferation, 2 had hyaline changes, 1 had local hemorrhage, 1 chronic inflammatory change, 2 had sequestration, 1 had dilated and congested vessels, and 1 had acute suppurative inflammation.

CONCLUSIONS

The most common pathologic characteristics were caseous necrosis, multinuclear giant cells, granulomatous inflammation, and tubercles. Moreover, multiple pathologic characteristics were observed in patients with spinal TB and one type of these characteristics was dominant. However, atypical pathologic characteristics were also noted. Thus, both pathologic examination and clinical analysis must be performed to improve the diagnostic rate of spinal TB.

Active Pulmonary Tuberculosis Triggered by Interferon Beta-1b Therapy of Multiple Sclerosis: Four Case Reports and a Literature Review

In this paper, we reported on four cases of severe pulmonary active tuberculosis in patients with multiple sclerosis (MS) undergoing interferon beta-1b (IFNβ-1b) therapy. Disease-modifying therapies (DMTs) in MS may increase the risk of developing active tuberculosis (TB) due to their impact on cellular immunity. Screening for latent infection with Mycobacterium tuberculosis (LTBI) should be performed, not only for the newer DMTs (alemtuzumab, ocrelizumab) but also for IFNβ-1b, alongside better supervision of these patients.

Toward a chimeric vaccine against multiple isolates of Mycobacteroides - An integrative approach

AIM

Nontuberculous mycobacterial (NTM) infection such as endophthalmitis, dacryocystitis, and canaliculitis are pervasive across the globe and are currently managed by antibiotics. However, the recent cases of Mycobacteroides developing drug resistance reported along with the improper practice of medicine intrigued us to explore its genomic and proteomic canvas at a global scale and develop a chimeric vaccine against Mycobacteroides.

MAIN METHODS

We carried out a vivid genomic study on five recently sequenced strains of Mycobacteroides and explored their Pan-core genome/proteome in three different phases. The promiscuous antigenic proteins were identified via a subtractive proteomics approach that qualified for virulence causation, resistance and essentiality factors for this notorious bacterium. An integrated pipeline was developed for the identification of B-Cell, MHC (Major histocompatibility complex) class I and II epitopes.

KEY FINDINGS

Phase I identified the shreds of evidence of reductive evolution and propensity of the Pan-genome of Mycobacteroides getting closed soon. Phase II and Phase III produced 8 vaccine constructs. Our final vaccine construct, V6 qualified for all tests such as absence for allergenicity, presence of antigenicity, etc. V6 contains β-defensin as an adjuvant, linkers, Lysosomal-associated membrane protein 1 (LAMP1) signal peptide, and PADRE (Pan HLA-DR epitopes) amino acid sequence. Besides, V6 also interacts with a maximum number of MHC molecules and the TLR4/MD2 (Toll-like receptor 4/Myeloid differentiation factor 2) complex confirmed by docking and molecular dynamics simulation studies.

SIGNIFICANCE

The knowledge harnessed from the current study can help improve the current treatment regimens or in an event of an outbreak and propel further related studies.

Identification and Classification of Differentially Expressed Genes and Network Meta-Analysis Reveals Potential Molecular Signatures Associated With Tuberculosis

Tuberculosis (TB) is one of deadly transmissible disease that causes death worldwide; however, only 10% of people infected with Mycobacteriumtuberculosis develop disease, indicating that host genetic factors may play key role in determining susceptibility to TB disease. In this way, the analysis of gene expression profiling of TB infected individuals can give us a snapshot of actively expressed genes and transcripts under various conditions. In the present study, we have analyzed microarray data set and compared the gene expression profiles of patients with different datasets of healthy control, latent infection, and active TB. We observed the transition of genes from normal condition to different stages of the TB and identified and annotated those genes/pathways/processes that have important roles in TB disease during its cyclic interventions in the human body. We identified 488 genes that were differentially expressed at various stages of TB and allocated to pathways and gene set enrichment analysis. These pathways as well as GSEA’s importance were evaluated according to the number of DEGs presents in both. In addition, we studied the gene regulatory networks that may help to further understand the molecular mechanism of immune response against the TB infection and provide us a new angle for future biomarker and therapeutic targets. In this study, we identified 26 leading hubs which are deeply rooted from top to bottom in the gene regulatory network and work as the backbone of the network. These leading hubs contains 31 key regulator genes, of which 14 genes were up-regulated and 17 genes were down-regulated. The proposed approach is based on gene-expression profiling, and network analysis approaches predict some unknown TB-associated genes, which can be considered (or can be tested) as reliable candidates for further (in vivo/in vitro) studies.

Serum level and single-nucleotide polymorphisms of toll-like receptor-7 among urinary bladder cancer Iraqi patients

Background

Toll-like receptor 7 (TLR7), a member of TLR family, plays a pivotal role in pathogenesis of different malignancies. Among these is urinary bladder cancer (UBC), which has not been extensively studied. Therefore, it was aimed to determine TLR7 serum level in UBC patients and evaluate its association with some demographic and clinicopathological characteristics. In addition, four TLR7 single-nucleotide polymorphisms (SNPs: rs179018, rs179019, rs179020, and rs179021) were investigated to determine their susceptibility role in UBC and inspect SNP’s impact on TLR7 level. Sixty-six UBC Iraqi patients were enrolled in this case-control study. Two control samples were also involved, 40 urinary tract infection (UTI) patients, and 48 healthy control subjects.

Results

Male gender, older age, and cigarette-smoking are risk factors for UBC. TLR7 level showed a significant decreased median in UBC patients compared to UTI patients or control (1.4 vs. 8.1 and 9.5 ng/ml, respectively; p < 0.001). The decrease was more pronounced in males, age group ≥ 48 years, cigarette-smokers, alcohol non-consumers, clinical stages I–II, and superficial tumor, as well as patients with family history of cancer and untreated patients. Mitomycin C and Bacillus Calmette–Guérin therapies tended to increase TLR7 level. Among the four investigated SNPs, only rs179019 C allele showed significantly uncorrected increased frequency in UBC males compared to control males (p = 0.038), while among UTI females, C allele frequency maintained a significantly corrected decreased frequency compared to control females (p = 0.005). Some SNPs influenced serum level of TLR7, but a significant impact was recorded for rs179019 in UTI females (p = 0.006).

Conclusions

Downregulation of TLR7 is suggested to have a role in etiology and pathogenesis of UBC, especially the male, elderly and smoker patients. Mitomycin C and Bacillus Calmette–Guérin may enhance TLR7 production in the blood of UBC patients. TLR7 SNPs are suggested to influence susceptibility to develop UBC, and their potential in impacting TLR7 serum level is augmented.

Gene expression profiling meta-analysis reveals novel gene signatures and pathways shared between tuberculosis and rheumatoid arthritis

Tuberculosis (TB) is among the leading causes of death by infectious diseases. An epidemiological association between Mycobacterium tuberculosis infection and autoimmune diseases like rheumatoid arthritis (RA) has been reported but it remains unclear if there is a causal relationship, and if so, which molecular pathways and regulatory mechanisms contribute to it. Here we used a computational biology approach by global gene expression meta-analysis to identify candidate genes and pathways that may link TB and RA. Data were collected from public expression databases such as NCBI GEO. Studies were selected that analyzed mRNA-expression in whole blood or blood cell populations in human case control studies at comparable conditions. Six TB and RA datasets (41 active TB patients, 33 RA patients, and 67 healthy controls) were included in the downstream analysis. This approach allowed the identification of deregulated genes that had not been identified in the single analysis of TB or RA patients and that were co-regulated in TB and RA patients compared to healthy subjects. The genes encoding TLR5, TNFSF10/TRAIL, PPP1R16B/TIMAP, SIAH1, PIK3IP1, and IL17RA were among the genes that were most significantly deregulated in TB and RA. Pathway enrichment analysis revealed 'T cell receptor signaling pathway', 'Toll-like receptor signaling pathway,' and 'virus defense related pathways' among the pathways most strongly associated with both diseases. The identification of a common gene signature and pathways substantiates the observation of an epidemiological association of TB and RA and provides clues on the mechanistic basis of this association. Newly identified genes may be a basis for future functional and epidemiological studies.

Cell death at the cross roads of host-pathogen interaction in Mycobacterium tuberculosis infection

Tuberculosis (TB) continues to be the leading cause of death by any single infectious agent, accounting for around 1.7 million annual deaths globally, despite several interventions and support programs by national and international agencies. With the development of drug resistance in Mycobacterium tuberculosis (M. tb), there has been a paradigm shift in TB research towards host-directed therapy. The potential targets include the interactions between host and bacterial proteins that are crucial for pathogenesis. Hence, collective efforts are being made to understand the molecular details of host-pathogen interaction for possible translation into host-directed therapy. The present review focuses on 'host cell death modalities' of host-pathogen interaction, which play a crucial role in determining the outcome of TB disease progression. Several cell death modalities that occur in response to mycobacterial infection have been identified in human macrophages either as host defences for bacterial clearance or as pathogen strategies for multiplication and dissemination. These cell death modalities include apoptosis, necrosis, pyroptosis, necroptosis, pyronecrosis, NETosis, and autophagy. These processes are highly overlapping with several mycobacterial proteins participating in more than one cell death pathway. Until now, reviews in M. tb and host cell death have discussed either focusing on host evasion strategies, apoptosis, autophagy, and necrosis or describing all these forms with limited discussions of their role in host-pathogen interactions. Here, we present a comprehensive review of various mycobacterial factors modulating host cell death pathways and the cross-talk between them. Besides this, we have discussed the networking of host cell death pathways including the interference of host miRNA during M. tb infection with their respective targets. Through this review, we present the host targets that overlap across several cell death modalities and the technical limitations of methodology in cell death research. Given the compelling need to discover alternative drug target(s), this review identifies these overlapping cell death factors as potential targets for host-directed therapy.

Influence of Genetic Polymorphism Towards Pulmonary Tuberculosis Susceptibility

Tuberculosis (TB) is still remains the major threat for human health worldwide. Several case-control, candidate-gene, family studies and genome-wide association studies (GWAS) suggested the association of host genetic factors to TB susceptibility or resistance in various ethnic populations. Moreover, these factors modulate the host immune responses to tuberculosis. Studies have reported genetic markers to predict TB development in human leukocyte antigen (HLA) and non-HLA genes like killer immunoglobulin-like receptor (KIR), toll-like receptors (TLRs), cytokine/chemokines and their receptors, vitamin D receptor (VDR) and SLC11A1 etc. Highly polymorphic HLA loci may influence antigen presentation specificities by modifying peptide binding motifs. The recent meta-analysis studies revealed the association of several HLA alleles in particular class II HLA-DRB1 with TB susceptibility and valuable marker for disease development especially in Asian populations. Case-control studies have found the association of HLA-DR2 in some populations, but not in other populations, this could be due to an ethnic specific association of gene variants. Recently, GWAS conducted in case-control and family based studies in Russia, Chinese Han, Morocco, Uganda and Tanzania revealed the association of genes such as ASAP1, Alkylglycerol monooxygenase (AGMO), Forkhead BoxP1 (FOXP1), C-terminal domain phosphatase 1 (UBLCP1) and intergenic SNP rs932347C/T with TB. Whereas, SNP rs10956514A/G were not associated with TB in western Chinese Han and Tibetan population. In this review, we summarize the recent findings of genetic variants with susceptibility/resistance to TB.