Molecular, metabolic, and functional CD4 T cell paralysis in the lymph node impedes tumor control.

CD4 T cells are central effectors of anti-cancer immunity and immunotherapy, yet the regulation of CD4 tumor-specific T (TTS) cells is unclear. We demonstrate that CD4 TTS cells are quickly primed and begin to divide following tumor initiation. However, unlike CD8 TTS cells or exhaustion programming, CD4 TTS cell proliferation is rapidly frozen in place by a functional interplay of regulatory T cells and CTLA4. Together these mechanisms paralyze CD4 TTS cell differentiation, redirecting metabolic circuits, and reducing their accumulation in the tumor. The paralyzed state is actively maintained throughout cancer progression and CD4 TTS cells rapidly resume proliferation and functional differentiation when the suppressive constraints are alleviated. Overcoming their paralysis established long-term tumor control, demonstrating the importance of rapidly crippling CD4 TTS cells for tumor progression and their potential restoration as therapeutic targets.

Microbial metabolite n-butyrate upregulates intestinal claudin-23 expression through SP1 and AMPK pathways in mouse colon and human intestinal Caco-2 cells.

AIMS: Regulation of the intestinal barrier is closely related to intestinal microbial metabolism. This study investigated the role of intestinal microflora in the regulation of the tight junction (TJ) barrier in epithelial cells, focusing on the microbial metabolite n-butyrate, a major short-chain fatty acid, using mice and human intestinal Caco-2 cells. MATERIALS AND METHODS: Whole transcriptome analysis with RNA sequencing and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were performed in the colon of germ-free (GF) and specific pathogen-free (SPF) mice. Claudin-23 expression was examined by qRT-PCR, immunoblotting, and immunofluorescence in Caco-2 cells treated with n-butyrate. Luciferase reporter assay was performed to examine the effect of n-butyrate on claudin-23 transcriptional activity. The siRNA targeting the transcription factor SP1 and pharmacological inhibitor of AMPK were used in combination. TJ permeability was examined in canine kidney MDCKII cells stably expressing human claudin-23. KEY FINDINGS: Cldn23 mRNA expression was downregulated in the colon of GF mice (0.6-fold) compared to that in SPF mice. n-Butyrate upregulated claudin-23 mRNA (1.7-fold) and protein (2.1-fold) expression as well as increased the transcriptional activity (15-fold) of CLDN23 in Caco-2 cells. The n-butyrate-mediated increase in claudin-23 expression and transcriptional activity was reduced by inhibition of SP1 and AMPK. Exogenously expressed human claudin-23 in MDCKII cells did not affect TJ permeability to ions and macromolecules. SIGNIFICANCE: n-Butyrate regulates intestinal claudin-23 expression through the SP1 and AMPK pathways. This mechanism may be involved in the beneficial effects of n-butyrate-mediated intestinal homeostasis.

Molecular, metabolic and functional CD4 T cell paralysis impedes tumor control.

CD4 T cells are important effectors of anti-tumor immunity, yet the regulation of CD4 tumor-specific T (T TS ) cells during cancer development is still unclear. We demonstrate that CD4 T TS cells are initially primed in the tumor draining lymph node and begin to divide following tumor initiation. Distinct from CD8 T TS cells and previously defined exhaustion programs, CD4 T TS cell proliferation is rapidly frozen in place and differentiation stunted by a functional interplay of T regulatory cells and both intrinsic and extrinsic CTLA4 signaling. Together these mechanisms paralyze CD4 T TS cell differentiation, redirecting metabolic and cytokine production circuits, and reducing CD4 T TS cell accumulation in the tumor. Paralysis is actively maintained throughout cancer progression and CD4 T TS cells rapidly resume proliferation and functional differentiation when both suppressive reactions are alleviated. Strikingly, Treg depletion alone reciprocally induced CD4 T TS cells to themselves become tumor-specific Tregs, whereas CTLA4 blockade alone failed to promote T helper differentiation. Overcoming their paralysis established long-term tumor control, demonstrating a novel immune evasion mechanism that specifically cripples CD4 T TS cells to favor tumor progression.

Association of relative deprivation with loneliness and its underlying mechanisms: Evidence from Chinese migrant children.

Given the increase in the number of internal migrant children, the mental health problems (e.g., loneliness) of this population have received widespread attention. Relative deprivation is considered to be related to migrant children's loneliness. However, the underlying mechanisms of this relationship remain unclear. Therefore, the present study tested the possible mediating role of self-esteem and the moderating role of belief in a just world in the association between relative deprivation and loneliness of migrant children. A total of 1,261 Chinese rural-to-urban migrant children (10-15 years old, M age = 12.34 years, SD = 1.67; 52.0% males, 48.0% females; 23.55% fourth grade students, 16.49% fifth grade students, 19.59% sixth grade students, 15.54% seventh grade students, 13.80% eighth grade students, and 10.86% ninth grade students) were recruited to complete measures of relative deprivation, self-esteem, belief in a just world, loneliness, and demographic variables. Relative deprivation was significantly and positively correlated with migrant children's loneliness, and this connection could be mediated by self-esteem. Moreover, the first part of the indirect effect of self-esteem on this link was moderated by belief in a just world. These effects were stronger for migrant children with higher levels of belief in a just world. This study reveals the potential mechanisms of relative deprivation affecting loneliness, while also providing insights into how to better help migrant children alleviate loneliness and improve their mental health.

Dynamic CD4+ T cell heterogeneity defines subset-specific suppression and PD-L1-blockade-driven functional restoration in chronic infection.

Inhibiting PD-1:PD-L1 signaling has transformed therapeutic immune restoration. CD4+ T cells sustain immunity in chronic infections and cancer, yet little is known about how PD-1 signaling modulates CD4+ helper T (TH) cell responses or the ability to restore CD4+ TH-mediated immunity by checkpoint blockade. We demonstrate that PD-1:PD-L1 specifically suppressed CD4+ TH1 cell amplification, prevents CD4+ TH1 cytokine production and abolishes CD4+ cytotoxic killing capacity during chronic infection in mice. Inhibiting PD-L1 rapidly restored these functions, while simultaneously amplifying and activating TH1-like T regulatory cells, demonstrating a system-wide CD4-TH1 recalibration. This effect coincided with decreased T cell antigen receptor signaling, and re-directed type I interferon (IFN) signaling networks towards dominant IFN-γ-mediated responses. Mechanistically, PD-L1 blockade specifically targeted defined populations with pre-established, but actively suppressed proliferative potential, with limited impact on minimally cycling TCF-1+ follicular helper T cells, despite high PD-1 expression. Thus, CD4+ T cells require unique differentiation and functional states to be targets of PD-L1-directed suppression and therapeutic restoration.

Hydrogen sulfide suppresses the proliferation of intestinal epithelial cells through cell cycle arrest.

The pathogenesis of chronic kidney disease (CKD) is closely related to the changes in the intestinal microbiota and integrity. Our previous studies have shown the accumulation of hydrogen sulfide (H2S)-producing bacterial family, Desulfovibrionacea, in the colon of a murine model of CKD, suggesting that the increased H2S contributes to the impaired intestinal integrity in CKD. Here, we investigated the anti-proliferative effect of H2S in the intestinal epithelial cells. A slow- H2S releasing molecule GYY4137 ((p-methoxyphenyl)morpholino-phosphinodithioic acid) reduced the proliferation of Caco-2 and IEC-6 cells. Flow cytometric analysis demonstrated that GYY4137 accumulated Caco-2 cells in the S phase fraction, suggesting that H2S arrested the cell cycle at G2 and/or M phases. The RNA sequencing analysis demonstrated that GYY4137 modulated the mRNA expression of the genes involved in the G2/M and the spindle assembly checkpoints; increased mRNA levels of Cdkn1a, Gadd45a, and Sfn and decreased mRNA levels of Cdc20, Pttg1, and Ccnb1 were observed. These alterations were confirmed by quantitative reverse transcription-polymerase chain reaction and Western blot analyses. Besides, studies exploring the MEK inhibitor indicated that MEK activation is involved in the GYY4137-mediated increase in the Sfn expression. Altogether, our data showed that H2S reduced the proliferation of intestinal epithelial cells through transcriptional regulation in G2/M and the spindle assembly checkpoints. This may be one of the underlying mechanisms for the observed impaired intestinal integrity in CKD.

3,5,7,3',4'-Pentamethoxyflavone Enhances the Barrier Function through Transcriptional Regulation of the Tight Junction in Human Intestinal Caco-2 Cells.

The intestinal tight junction (TJ) barrier plays a pivotal role in the regulation of intestinal homeostasis. This study investigated the effects of 3,5,7,3',4'-pentamethoxyflavone (PMF), a major polymethoxyflavone found in black ginger, on TJ barrier regulation using intestinal Caco-2 cells. PMF treatment enhanced the TJ barrier integrity in Caco-2 cells, indicated by increased transepithelial electrical resistance (control, 1261 ± 36 Ω·cm2; 100 µM PMF, 1383 ± 55 Ω·cm2 at 48 h, p < 0.05) and decreased permeability to fluorescein-conjugated dextran (control, 24.2 ± 1.8 pmol/(cm2 × h); 100 µM PMF, 18.6 ± 1.0 pmol/(cm2 × h), p < 0.05). Immunoblot analysis revealed that PMF increased the cytoskeletal association and cellular expression of the TJ proteins, zonula occludens-1, claudin-3, and claudin-4 (e.g., occludin; control, 1.00 ± 0.2; 100 µM PMF, 3.69 ± 0.86 at 48 h, p < 0.05). Quantitative reverse transcriptase-polymerase chain reaction analysis and a luciferase promoter assay showed that PMF enhanced the transcription of occludin, claudin-3, and claudin-4. The promoter assay with site-directed mutagenesis indicated that PMF-induced occludin and claudin-3 transcription was mediated by transcription factors, KLF5 and EGR1, respectively, while PMF activated claudin-4 transcription through GATA1 and AP1. Taken together, the transcriptional regulation of TJ proteins is involved in PMF-mediated promotion of the intestinal barrier in vitro.

Curcumin increases heat shock protein 70 expression via different signaling pathways in intestinal epithelial cells.

Intestinal inflammation is associated with the integrity of the intestinal epithelium, which forms a physical barrier against noxious luminal substances. Heat shock 70 kDa protein 1A (HSP70), a molecular chaperon that exerts a cytoprotective effect, regulates intestinal integrity. This study investigated the modulation of HSP70 expression by dietary polyphenols, with particular reference to curcumin, in human intestinal Caco-2 cells. Immunoblot analysis demonstrated that among the 21 different polyphenols tested, curcumin most potently increased HSP70 levels in Caco-2 cells without affecting cell viability. Curcumin also increased the phosphorylation of heat shock factor 1 (HSF1), a well-known transcription factor of HSP70. Promoter and qRT-PCR assays indicated that curcumin upregulated Hspa1a levels via transcriptional activation. Pharmacological inhibition of MEK, a mechanistic target of rapamycin, p38 mitogen-activated protein kinase, and phosphatidyl 3-inositol kinase suppressed curcumin-mediated HSP70 expression, whereas HSF1 phosphorylation was sensitive only to MEK inhibition. Taken together, curcumin increases the expression of HSP70 in intestinal Caco-2 cells via transcriptional activation, possibly enhancing cell integrity. The effects exerted by curcumin are regulated by various signaling pathways. Our findings will expectedly contribute to a deeper understanding of the regulation of intestinal HSP70 by dietary components.

Early innate and adaptive immune perturbations determine long-term severity of chronic virus and Mycobacterium tuberculosis coinfection.

Chronic viral infections increase severity of Mycobacterium tuberculosis (Mtb) coinfection. Here, we examined how chronic viral infections alter the pulmonary microenvironment to foster coinfection and worsen disease severity. We developed a coordinated system of chronic virus and Mtb infection that induced central clinical manifestations of coinfection, including increased Mtb burden, extra-pulmonary dissemination, and heightened mortality. These disease states were not due to chronic virus-induced immunosuppression or exhaustion; rather, increased amounts of the cytokine TNFα initially arrested pulmonary Mtb growth, impeding dendritic cell mediated antigen transportation to the lymph node and subverting immune-surveillance, allowing bacterial sanctuary. The cryptic Mtb replication delayed CD4 T cell priming, redirecting T helper (Th) 1 toward Th17 differentiation and increasing pulmonary neutrophilia, which diminished long-term survival. Temporally restoring CD4 T cell induction overcame these diverse disease sequelae to enhance Mtb control. Thus, Mtb co-opts TNFα from the chronic inflammatory environment to subvert immune-surveillance, avert early immune function, and foster long-term coinfection.

A network of immune and microbial modifications underlies viral persistence in the gastrointestinal tract.

Many pathogens subvert intestinal immunity to persist within the gastrointestinal tract (GIT); yet, the underlying mechanisms that enable sanctuary specifically in this reservoir are unclear. Using mass cytometry and network analysis, we demonstrate that chronic LCMV infection of the GIT leads to dysregulated microbial composition, a cascade of metabolic alterations, increased susceptibility to GI disease, and a system-wide recalibration of immune composition that defines viral persistence. Chronic infection led to outgrowth of activated Tbet-expressing T reg cell populations unique to the GIT and the rapid erosion of pathogen-specific CD8 tissue-resident memory T cells. Mechanistically, T reg cells and coinhibitory receptors maintained long-term viral sanctuary within the GIT, and their targeting reactivated T cells and eliminated this viral reservoir. Thus, our data provide a high-dimensional definition of the mechanisms of immune regulation that chronic viruses implement to exploit the unique microenvironment of the GIT and identify T reg cells as key modulators of viral persistence in the intestinal tract.

Validation of CyTOF Against Flow Cytometry for Immunological Studies and Monitoring of Human Cancer Clinical Trials.

Flow cytometry is a widely applied approach for exploratory immune profiling and biomarker discovery in cancer and other diseases. However, flow cytometry is limited by the number of parameters that can be simultaneously analyzed, severely restricting its utility. Recently, the advent of mass cytometry (CyTOF) has enabled high dimensional and unbiased examination of the immune system, allowing simultaneous interrogation of a large number of parameters. This is important for deep interrogation of immune responses and particularly when sample sizes are limited (such as in tumors). Our goal was to compare the accuracy and reproducibility of CyTOF against flow cytometry as a reliable analytic tool for human PBMC and tumor tissues for cancer clinical trials. We developed a 40+ parameter CyTOF panel and demonstrate that compared to flow cytometry, CyTOF yields analogous quantification of cell lineages in conjunction with markers of cell differentiation, function, activation, and exhaustion for use with fresh and viably frozen PBMC or tumor tissues. Further, we provide a protocol that enables reliable quantification by CyTOF down to low numbers of input human cells, an approach that is particularly important when cell numbers are limiting. Thus, we validate CyTOF as an accurate approach to perform high dimensional analysis in human tumor tissue and to utilize low cell numbers for subsequent immunologic studies and cancer clinical trials.

Membralin deficiency dysregulates astrocytic glutamate homeostasis leading to ALS-like impairment.

Mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) are yet unclear. Specific deletion of the ER-component membralin in astrocytes manifested postnatal motor defects and lethality in mice, causing the accumulation of extracellular glutamate through reducing the glutamate transporter EAAT2. Restoring EAAT2 levels in membralin KO astrocytes limited astrocyte-dependent excitotoxicity in motor neurons. Transcriptomic profiles from mouse astrocytic membralin KO motor cortex indicated significant perturbation in KEGG pathway components related to ALS, including downregulation of Eaat2 and upregulation of Tnfrsf1a. Changes in gene expression with membralin deletion also overlapped with mouse ALS models and reactive astrocytes. Our results shown that activation of TNF receptor (TNFR1)-NFκB pathway known to suppress Eaat2 transcription was upregulated with membralin deletion. Further, reduced membralin and EAAT2 levels correlated with disease progression in spinal cord from SOD1-mutant mouse models, and reductions in membralin/EAAT2 were observed in human ALS spinal cord. Importantly, overexpression of membralin in SOD1G93A astrocytes decreased TNFR1 levels and increased EAAT2 expression, and improved motor neuron survival. Importantly, upregulation of membralin in SOD1G93A mice significantly prolonged mouse survival. Together, our study provided a mechanism for ALS pathogenesis where membralin limited glutamatergic neurotoxicity, suggesting that modulating membralin had potentials in ALS therapy.

Humane Endpoints for Guinea Pigs Used for Mycobacterium tuberculosis Vaccine Research.

Guinea pigs are a commonly used model for tuberculosis vaccine research. Loss of body weight is the most frequently described humane endpoint for animals used in these studies. During a chronic study, we noted labored breathing in some tuberculosis-infected guinea pigs. To develop consistent humane endpoints for these guinea pigs, we performed an observational study using multiple clinical signs. A combination of body weight loss, labored breathing, and activity level during handling estimated the time to euthanasia within approximately 7 d. Histologic severity scores of lesions in the cranial or caudal lung lobe (or both) supported clinical endpoints. This study presents humane endpoints for the refinement of studies using guinea pigs in tuberculosis research.

Rv2629 Overexpression Delays Mycobacterium smegmatis and Mycobacteria tuberculosis Entry into Log-Phase and Increases Pathogenicity of Mycobacterium smegmatis in Mice.

Objective: The aim of the present study was to explore the potential biological role of Rv2629 in Mycobacterium smegmatis and Mycobacterium tuberculosis.Methods: Recombinant wild type and mutant Rv2629 strains were constructed. Rv2629 expression was evaluated by real-time PCR and western blot. Microarray and interaction network analyses were used to identify the gene interactions associated with wild type and mutant Rv2629. Bacterial growth was assessed in Balb/c mice infected with wild type and mutant Rv2629 strains using CFU assay and histological analysis of the organs. Results: Overexpression of Rv2629 could delay the entry of the Mycobacterium tuberculosis cells into the log-phase, while Rv2629 decreased the number of ribosomes and the expression of uridylate kinase in Mycobacterium smegmatis. The Gene Ontology (GO) and pathway analysis indicated that 122 genes correlated with wild type Rv2629, whereas the Rv2629 mutation led to decrease in the ribosome production, oxidative phosphorylation, and virulence in Mycobacterium tuberculosis. Overexpression of Rv2629 slightly enhanced the drug resistance of Mycobacterium smegmatis to antibiotics, and increased its survival and pathogenicity in Balb/c mice. Conclusion: It is suggested that Rv2629 is involved in the survival of the clinical drug-resistant strain via bacterial growth repression and bacterial persistence induction.

Fine particulate matter constituents and blood pressure in patients with chronic obstructive pulmonary disease: A panel study in Shanghai, China.

OBJECTIVE: The evidence is limited about the potentially different health effects of various chemical constituents of fine particulate matter (PM2.5). We thus assessed the acute effects of various chemical constituents of PM2.5 on blood pressure (BP). METHODS: We performed a longitudinal panel study with six repeated visits in 28 urban residents with chronic obstructive pulmonary disease in Shanghai, China from May to July, 2014. Twelve (43%) of them took antihypertensive medications. We measured resting BP by using a mercury sphygmomanometer and monitored real-time concentrations of PM2.5 constituents at a nearby site. Based on the linear mixed-effects model, we evaluated the effects of 10 major constituents in PM2.5 on BP, using a single-constituent model and a constituent-residual model after accounting for the multicollinearity. RESULTS: We obtained a total of 168 pairs of effective BP measurements during the study period. There are moderate or high correlations among various PM2.5 constituents. An interquartile range increase of PM2.5 (19.1µg/m3) was associated with increments of 1.90mmHg [95% confidence interval (CI): 0.66, 3.13] in systolic BP, 0.68mmHg (95%CI: -0.02, 1.37) in diastolic BP and 1.23mmHg (95%CI: 0.19, 2.29) in pulse pressure. Some constituents of PM2.5, including organic carbon, elemental carbon, nitrate and ammonium, were robustly associated with elevated BP after controlling for total PM2.5 mass and accounting for multi-collinearity. Two constituents (magnesium and calcium) were associated with decreased BP. CONCLUSIONS: Organic carbon, elemental carbon, nitrate and ammonium may be mainly responsible for elevated BP from a short-term exposure to PM2.5.

The Acute Effects of Fine Particulate Matter Constituents on Blood Inflammation and Coagulation.

Limited evidence is available on the effects of various fine particulate matter (PM2.5) constituents on blood inflammation and coagulation. We examined the associations between 10 constituents and 10 circulating biomarkers in a panel of 28 urban residents with four repeated measurements in Shanghai, China. Based on the linear mixed-effect models, we fitted the single-constituent models, the constituent-PM2.5 joint models, and the constituent-residual models to evaluate the associations between PM2.5 constituents and eight inflammatory biomarkers (fibrinogen, C-reactive protein, monocyte chemoattractant protein-1, tumor necrosis factor-α, interleukin-1b, intercellular adhesion molecule-1, P-selectin, vascular cell adhesion molecule-1) and two coagulation biomarkers (plasminogen activator inhibitor-1 and soluble CD40 ligand). We found robust associations of organic carbon (OC), elemental carbon (EC), nitrate (NO3-), and ammonium (NH4+) with at least 1 of 8 inflammatory markers. On average, an interquartile range increase in the four constituents corresponded to increments of 50%, 37%, 25%, and 26% in inflammatory biomarkers, respectively. Only sulfate (SO42-) or NH4+ was robustly associated with coagulation markers (corresponding increments: 23% and 20%). Our results provided evidence that some constituents in PM2.5 (OC, EC, NO3-, SO42-, and NH4+) might play crucial roles in inducing systematic inflammation and coagulation, but their roles varied by the selected biomarkers.

Variable Virulence and Efficacy of BCG Vaccine Strains in Mice and Correlation With Genome Polymorphisms.

Bacille Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis, is the only vaccine available for tuberculosis (TB) control. However, BCG is not an ideal vaccine and has two major limitations: BCG exhibits highly variable effectiveness against the development of TB both in pediatric and adult populations and can cause disseminated BCG disease in immunocompromised individuals. BCG comprises a number of substrains that are genetically distinct. Whether and how these genetic differences affect BCG efficacy remains largely unknown. In this study, we performed comparative analyses of the virulence and efficacy of 13 BCG strains, representing different genetic lineages, in SCID and BALB/c mice. Our results show that BCG strains of the DU2 group IV (BCG-Phipps, BCG-Frappier, BCG-Pasteur, and BCG-Tice) exhibit the highest levels of virulence, and BCG strains of the DU2 group II (BCG-Sweden, BCG-Birkhaug) are among the least virulent group. These distinct levels of virulence may be explained by strain-specific duplications and deletions of genomic DNA. There appears to be a general trend that more virulent BCG strains are also more effective in protection against Mycobacterium tuberculosis challenge. Our findings have important implications for current BCG vaccine programs and for future TB vaccine development.

Fine Particulate Matter Constituents, Nitric Oxide Synthase DNA Methylation and Exhaled Nitric Oxide.

It remains unknown how fine particulate matter (PM2.5) constituents affect differently the fractional concentration of exhaled nitric oxide (FeNO, a biomarker of airway inflammation) and the DNA methylation of its encoding gene (NOS2A). We aimed to investigate the short-term effects of PM2.5 constituents on NOS2A methylation and FeNO. We designed a longitudinal study among chronic obstructive pulmonary disease (COPD) patients with six repeated health measurements in Shanghai, China. We applied linear mixed-effect models to evaluate the associations. We observed that the inverse association between PM2.5 and methylation at position 1 was limited within 24 h, and the positive association between PM2.5 and FeNO was the strongest at lag 1 day. Organic carbon, element carbon, NO3(-) and NH4(+) were robustly and significantly associated with decreased methylation and elevated FeNO. An interquartile range increase in total PM2.5 and the four constituents was associated with decreases of 1.19, 1.63, 1.62, 1.17, and 1.14 in percent methylation of NOS2A, respectively, and increases of 13.30%,16.93%, 8.97%, 18.26%, and 11.42% in FeNO, respectively. Our results indicated that organic carbon, element carbon, NO3(-) and NH4(+) might be mainly responsible for the effects of PM2.5 on the decreased NOS2A DNA methylation and elevated FeNO in COPD patients.

The Wag31 protein interacts with AccA3 and coordinates cell wall lipid permeability and lipophilic drug resistance in Mycobacterium smegmatis.

Mycobacterium tuberculosis, especially drug resistant tuberculosis, is a serious threat to global human health. Compared with other bacterial pathogens, M. tuberculosis gains stronger natural drug resistance from its unusually lipid-rich cell wall. As a DivIVA homolog, Wag31 has been demonstrated to be closely involved in peptidoglycan synthesis, cell growth and cell division. Previous research rarely investigated the role of Wag31 in drug resistance. In this study, we found Wag31 knock-down in Mycobacterium smegmatis resulted in a co-decrease of the resistance to four lipophilic drugs (rifampicin, novobiocin, erythromycin and clofazimine) and an increase in the cell permeability to lipophilic molecules. Six proteins (AccA3, AccD4 and AccD5, Fas, InhA and MmpL3) that are involved in fatty acid and mycolic acid synthesis were identified in the Wag31 interactome through Co-Immunoprecipitation. The Wag31-AccA3 interaction was confirmed by the pull-down assay. AccA3 overexpression resulted in a decrease in lipid permeability and an increase in the resistance of rifampicin and novobiocin. It confirmed the close relationship of lipophilic drug resistance, lipid permeability and the Wag31-AccA3 interaction. These results demonstrated that Wag31 maintained the resistance to lipophilic drugs and that Wag31 could play a role in controlling the lipid permeability of the cell wall through the Wag31-AccA3 interaction.

A novel method of identifying Mycobacterium tuberculosis Beijing strains by detecting SNPs in Rv0444c and Rv2629.

A particular genotype of tuberculosis, named Beijing strain, is strongly associated with drug resistance and high virulence. Therefore, rapid prospective identification of Mycobacterium tuberculosis Beijing strains is very important for identifying and controlling tuberculosis of Beijing genotype. In the present study, we found that the co-mutation, A191C in Rv2629 and G243C in Rv0444c, is closely related to Beijing genotype. Gene Rv2629 and Rv0444c of 139 clinical isolates of M. tuberculosis were analyzed by PCR amplification and sequencing. Among 99 Beijing strains, 86 % (n = 85) isolates had the mutation G243C in Rv0444c and 92.93 % (n = 92) isolates had the mutation A191C in Rv2629. Among 40 non-Beijing isolates, only six isolates carried the mutation G243C in Rv0444c and eight isolates carried the mutation A191C in Rv2629. The co-mutation existed in 84.85 % (n = 84) of 99 clinical genome samples of W-Beijing strains and in only 12.5 % (n = 5) of the 40 non-Beijing strains, and the positive predictive value of 94.38 %, obtained in our experiment with a designed ratio of Beijing isolates, is similar to that in China at present. This result suggested that the detection method of the co-mutation, A191C in Rv2629 and G243C in Rv0444c, proposed in this study was a rapid, reliable, and sensitive one for identifying tuberculosis with Beijing genotype.