Failure to recruit anti-inflammatory CD103+ dendritic cells and a diminished CD4+ Foxp3+ regulatory T cell pool in mice that display excessive lung inflammation and increased susceptibility to Mycobacterium tuberculosis

Susceptibility to Mycobacterium tuberculosis is characterized by excessive lung inflammation, tissue damage, and failure to control bacterial growth. To increase our understanding of mechanisms that may regulate the host immune response in the lungs, we characterized dendritic cells expressing CD103 (α(E) integrin) (αE-DCs) and CD4(+) Foxp3(+) regulatory T (T(reg)) cells during M. tuberculosis infection. In resistant C57BL/6 and BALB/c mice, the number of lung αE-DCs increased dramatically during M. tuberculosis infection. In contrast, highly susceptible DBA/2 mice failed to recruit αE-DCs even during chronic infection. Even though tumor necrosis factor alpha (TNF-α) is produced by multiple DCs and macrophage subsets and is required for control of bacterial growth, αE-DCs remained TNF-α negative. Instead, αE-DCs contained a high number of transforming growth factor beta-producing cells in infected mice. Further, we show that T(reg) cells in C57BL/6 and DBA/2 mice induce gamma interferon during pulmonary tuberculosis. In contrast to resistant mice, the T(reg) cell population was diminished in the lungs, but not in the draining pulmonary lymph nodes (PLN), of highly susceptible mice during chronic infection. T(reg) cells have been reported to inhibit M. tuberculosis-specific T cell immunity, leading to increased bacterial growth. Still, despite the reduced number of lung T(reg) cells in DBA/2 mice, the bacterial load in the lungs was increased compared to resistant animals. Our results show that αE-DCs and T(reg) cells that may regulate the host immune response are increased in M. tuberculosis-infected lungs of resistant mice but diminished in infected lungs of susceptible mice.     

Anti‐SARS‐CoV‐2 IgG antibody levels among Thai healthcare providers receiving homologous and heterologous COVID‐19 vaccination regimens

BackgroundWe examined SARS‐CoV‐2 anti‐spike 1 IgG antibody levels following COVID‐19 vaccination (AstraZeneca [AZ], Sinovac [SV], Pfizer‐BioNTech [PZ]) among Thai healthcare providers.MethodsBlood specimens were tested using enzyme‐linked immunosorbent assay. We analyzed seven vaccination regimens: (1) one dose of AZ or SV, (2) two doses of homologous (2AZ, 2SV) or heterologous (1AZ + 1PZ) vaccines, and (3) three doses of heterologous vaccines (2SV + 1AZ, 2SV + 1PZ). Differences in antibody levels were assessed using Kruskal–Wallis statistic, Mann–Whitney test, or Wilcoxon matched‐pairs signed‐rank test. Antibody kinetics were predicted using fractional polynomial regression.ResultsThe 563 participants had median age of 39 years; 92% were female; 74% reported no underlying medical condition. Antibody levels peaked at 22–23 days in both 1AZ and 2SV vaccinees and dropped below assay''s cutoff for positive (35.2 binding antibody units/ml [BAU/ml]) in 55 days among 1AZ vaccinees compared with 117 days among 2SV vaccinees. 1AZ + 1PZ vaccination regimen was highly immunogenic (median 2279 BAU/ml) 1–4 weeks post vaccination. 2SV + 1PZ vaccinees had significantly higher antibody levels than 2SV + 1AZ vaccinees 4 weeks post vaccination (3423 vs. 2105 BAU/ml; p‐value < 0.01), and during weeks 5–8 (3656 vs. 1072 BAU/ml; p‐value < 0.01). Antibodies peaked at 12–15 days in both 2SV + 1PZ and 2SV + 1AZ vaccinees, but those of 2SV + 1AZ declined more rapidly and dropped below assay''s cutoff in 228 days while those of 2SV + 1PZ remained detectable.Conclusions1AZ + 1PZ, 2SV + 1AZ, and 2SV + 1PZ vaccinees had substantial IgG levels, suggesting that these individuals likely mounted sufficient anti‐S1 IgG antibodies for possible protection against SARS‐CoV‐2 infection.     

Antigen-Presenting Cell Characteristics of Human γδ T Lymphocytes in Chronic Myeloid Leukemia

Human γδ T lymphocytes play a role in the immune system defense against cancer. Their broad anti-cancer activity against different types of cancers makes them outstanding candidates for cancer immunotherapy. An issue of recent interest is whether their antigen presentation features are similar to mature dendritic cells. The antigen-presenting cell (APC)-like phenotype and function of γδ T lymphocytes have been confirmed in many clinical trials. In this study, to support the strong role played by Vγ9Vδ2 T cells against cancer, we provide evidence that Vγ9Vδ2 T cells activated with chronic myeloid leukemia (CML) cell lysate antigens can efficiently express an APC phenotype and function. Vγ9Vδ2 T cells derived from normal peripheral blood mononuclear cells were activated with tumor cell lysate, and the tumor-activated Vγ9Vδ2 T cells could recognize and kill CML through their cytotoxic activity. In conclusion, the Vγ9Vδ2 T cells activated by cancer cell lysate showed APC characteristics, and this may greatly increase interest in investigating their therapeutic potential in hematologic malignancies.

Abbreviations: CML: chronic myeloid leukemia; APC: antigen-presenting cell; TCR: T cell receptor; MHC: major histocompatibility complex; N-BPs: nitrogen-containing bisphosphonates; IPP: isopentenyl pyrophosphate; PBMC: peripheral blood mononuclear cells; NKG2D: natural killer receptor group 2, member D; TRAIL: tumor necrosis factor-related apoptosis-inducing ligand.     

Sensitive detection of the IS6110 sequence of Mycobacterium tuberculosis complex based on PCR-magnetic bead ELISA

Tuberculosis (TB) is ranked as the top killer among infectious diseases worldwide. Early and accurate diagnosis of the disease is crucial to end the global TB epidemic. The current commercially available molecular tests are still unaffordable by most TB affected communities. Herein, we developed a novel rapid and sensitive diagnostic method to detect the IS6110 sequence of Mycobacterium tuberculosis (M. tuberculosis) complex using PCR-magnetic bead ELISA. PCR amplification ofa 123 bp repetitive sequence of the IS6110 gene was performed by using digoxigenin (DIG) and biotin-labelled primers. Streptavidin-conjugated magnetic beads were used to collect the dual-labelled amplicons and subsequently, colourimetric detection was done by using horseradish peroxidase (HRP)-conjugated anti-DIG antibody. This method is able to detect M. tuberculosis DNA down to 0.5 fg per reaction within 3 hours. The sensitivity of IS6110 PCR detection by magnetic bead ELISA is 100 times higher than that of conventional agarose gel electrophoresis. The assay specificity was determined using a panel of DNA extracted from 10 common bacteria causing lower respiratory tract infections. No cross-reactivity was detected from those bacteria by IS6110 PCR-magnetic bead ELISA. Thus, the novel highly sensitive and specific, reduced assay time and simplicity of this PCR-magnetic bead ELISA for the detection of the specific gene of M. tuberculosis complex makes it an attractive diagnostic tool for large-scale screening of tuberculosis in standard clinical laboratories.

Tuberculosis (TB) is ranked as the top killer among infectious diseases worldwide.     

Clusters of Drug-Resistant Mycobacterium tuberculosis Detected by Whole-Genome Sequence Analysis of Nationwide Sample,Thailand, 2014–2017

Multidrug-resistant tuberculosis (MDR TB), pre-extensively drug-resistant tuberculosis (pre-XDR TB), and extensively drug-resistant tuberculosis (XDR TB) complicate disease control. We analyzed whole-genome sequence data for 579 phenotypically drug-resistant M. tuberculosis isolates (28% of available MDR/pre-XDR and all culturable XDR TB isolates collected in Thailand during 2014–2017). Most isolates were from lineage 2 (n = 482; 83.2%). Cluster analysis revealed that 281/579 isolates (48.5%) formed 89 clusters, including 205 MDR TB, 46 pre-XDR TB, 19 XDR TB, and 11 poly–drug-resistant TB isolates based on genotypic drug resistance. Members of most clusters had the same subset of drug resistance-associated mutations, supporting potential primary resistance in MDR TB (n = 176/205; 85.9%), pre-XDR TB (n = 29/46; 63.0%), and XDR TB (n = 14/19; 73.7%). Thirteen major clades were significantly associated with geography (p<0.001). Clusters of clonal origin contribute greatly to the high prevalence of drug-resistant TB in Thailand.