Complexity and Controversies over the Cytokine Profiles of T Helper Cell Subpopulations in Tuberculosis

Mitochondrial Transplantation Promotes Protective Effector and Memory CD4+ T Cell Response During Mycobacterium Tuberculosis Infection and Diminishes Exhaustion and Senescence in Elderly CD4+ T cells

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), is a major global health concern, particularly affecting those with weakened immune systems, including the elderly. CD4+ T cell response is crucial for immunity against M.tb, but chronic infections and aging can lead to T cell exhaustion and senescence, worsening TB disease. Mitochondrial dysfunction, prevalent in aging and chronic diseases, disrupts cellular metabolism, increases oxidative stress, and impairs T-cell functions. This study investigates the effect of mitochondrial transplantation (mito-transfer) on CD4+ T cell differentiation and function in aged mouse models and human CD4+ T cells from elderly individuals. Mito-transfer in naïve CD4+ T cells is found to promote protective effector and memory T cell generation during M.tb infection in mice. Additionally, it improves elderly human T cell function by increasing mitochondrial mass and altering cytokine production, thereby reducing markers of exhaustion and senescence. These findings suggest mito-transfer as a novel approach to enhance aged CD4+ T cell functionality, potentially benefiting immune responses in the elderly and chronic TB patients. This has broader implications for diseases where mitochondrial dysfunction contributes to T-cell exhaustion and senescence.

Progress in mechanism-based diagnosis and treatment of tuberculosis comorbid with tumor

Tuberculosis (TB) and tumor, with similarities in immune response and pathogenesis, are diseases that are prone to produce autoimmune stress response to the host immune system. With a symbiotic relationship between the two, TB can facilitate the occurrence and development of tumors, while tumor causes TB reactivation. In this review, we systematically sorted out the incidence trends and influencing factors of TB and tumor, focusing on the potential pathogenesis of TB and tumor, to provide a pathway for the co-pathogenesis of TB comorbid with tumor (TCWT). Based on this, we summarized the latest progress in the diagnosis and treatment of TCWT, and provided ideas for further exploration of clinical trials and new drug development of TCWT.

Evaluation of the Immunogenicity of Recombinant Espb, Espc Proteins from Mycobacterium Tuberculosis and the Fusion Espc/Espb Protein in BALB/C Mice

Background

Two newly identified proteins, EspB and EspC are involved in the pathogenesis of Mycobacterium tuberculosis. The objective of the present study was to evaluate the immunogenicity of recombinant EspC, EspB, and EspC/EspB fusion proteins in mice.

Methods

BALB/c mice were immunized subcutaneously with recombinant EspC, EspB, and fusion EspC/EspB proteins, three times with along with Quil-A as an adjuvant. The cellular and humoral immune responses were evaluated by quantifying IFN-γ, IL-4, IgG, IgG1, and IgG2a antibodies against the antigens.

Results

The results showed that the mice immunized with recombinant EspC, EspB, and EspC/EspB proteins did not produce IL-4, whereas IFN-γ was secreted in response to all three proteins. EspC/EspB group produced significant amounts of IFN-γ in response to stimulation with all the three recombinant proteins (P<0.001). In mice immunized with EspC, high levels of IFN-γ were detected in response to EspC/EspB, and EspC (P<0.0001); while mice immunized with EspB produced lower levels of IFN-γ in response to EspC/EspB, and EspB (P<0.05).Mice immunized with recombinant EspC, EspB, and EspC/EspB proteins exhibited significantly high levels of IgG and IgG2a/IgG1 ratio (P< 0.001). Moreover, high levels of IgG and IgG2a were detected in the sera of mice immunized with EspC/EspB fusion protein.

Conclusions

All the three recombinant proteins induced Th1-type immune responses in mice against EspB and EspC; however, EspC/EspB protein is more desirable due to the presence of epitopes from both EspC and EspB proteins and the production of immune responses against both.

Vitreous proteomics, a gateway to improved understanding and stratification of diverse uveitis aetiologies

PURPOSE

The vitreous proteome might provide an attractive gateway to discriminate between various uveitis aetiologies and gain novel insights into the underlying pathophysiological processes. Here, we investigated 180 vitreous proteins to discover novel biomarkers and broaden disease insights by comparing (1). primary vitreoretinal lymphoma ((P)VRL) versus other aetiologies, (2). sarcoid uveitis versus tuberculosis (TB)-associated uveitis and (3). granulomatous (sarcoid and TB) uveitis versus other aetiologies.

METHODS

Vitreous protein levels were determined by proximity extension assay in 47 patients with intraocular inflammation and a prestudy diagnosis (cohort 1; training) and 22 patients with a blinded diagnosis (cohort 2; validation). Differentially expressed proteins identified by t-tests on cohort 1 were used to calculate Youden's indices. Pathway and network analysis was performed by ingenuity pathway analysis. A random forest classifier was trained to predict the diagnosis of blinded patients.

RESULTS

For (P)VRL stratification, the previously reported combined diagnostic value of IL-10 and IL-6 was confirmed. Additionally, CD70 was identified as potential novel marker for (P)VRL. However, the classifier trained on the entire cohort (cohort 1 and 2) relied primarily on the interleukin score for intraocular lymphoma diagnosis (ISOLD) or IL-10/IL-6 ratio and only showed a supportive role for CD70. Furthermore, sarcoid uveitis displayed increased levels of vitreous CCL17 as compared to TB-associated uveitis.

CONCLUSION

We underline the previously reported value of the ISOLD and the IL-10/IL-6 ratio for (P)VRL identification and present CD70 as a potentially valuable target for (P)VRL stratification. Finally, we also show that increased CCL17 levels might help to distinguish sarcoid uveitis from TB-associated uveitis.

c-di-AMP Accumulation Regulates Growth, Metabolism, and Immunogenicity of Mycobacterium smegmatis

Cyclic dimeric adenosine monophosphate (c-di-AMP) is a ubiquitous second messenger of bacteria involved in diverse physiological processes as well as host immune responses. MSMEG_2630 is a c-di-AMP phosphodiesterase (cnpB) of Mycobacterium smegmatis, which is homologous to Mycobacterium tuberculosis Rv2837c. In this study, cnpB-deleted (ΔcnpB), -complemented (ΔcnpB::C), and -overexpressed (ΔcnpB::O) strains of M. smegmatis were constructed to investigate the role of c-di-AMP in regulating mycobacterial physiology and immunogenicity. This study provides more precise evidence that elevated c-di-AMP level resulted in smaller colonies, shorter bacteria length, impaired growth, and inhibition of potassium transporter in M. smegmatis. This is the first study to report that elevated c-di-AMP level could inhibit biofilm formation and induce porphyrin accumulation in M. smegmatis by regulating associated gene expressions, which may have effects on drug resistance and virulence of mycobacterium. Moreover, the cnpB-deleted strain with an elevated c-di-AMP level could induce enhanced Th1 immune responses after M. tuberculosis infection. Further, the pathological changes and the bacteria burden in ΔcnpB group were comparable with the wild-type M. smegmatis group against M. tuberculosis venous infection in the mouse model. Our findings enhanced the understanding of the physiological role of c-di-AMP in mycobacterium, and M. smegmatis cnpB-deleted strain with elevated c-di-AMP level showed the potential for a vaccine against tuberculosis.

A novel nanomicelle composed from PEGylated TB di-peptide could be successfully used as a BCG booster

Objectives

Tuberculosis affects one-third of the world's population and leads to a high rate of morbidity and mortality. Bacillus Chalmette-Guerin (BCG) as the only approved vaccine for the Mycobacterium tuberculosis (Mtb) does not show enough protection in the vaccinated population.

Materials and Methods

The main aim of this study was to prepare a self-assembled nanomicelle composed from a di-block polymer in which, a di-fusion peptide was the hydrophobic block and polyethylene glycol (PEG) was the hydrophilic block. The micelles were characterized in vitro and in vivo as an antigen delivery system/adjuvant both with and without a prime BCG.

Results

The micellar nanovaccine was able to elicit good dendritic cell maturation. Nanomicelles could efficiently induce systemic cytokines as well as nasal secretory predominant antibody titers (sIgA). The expression pattern of cytokines indicated the superiority of cellular immunity. Nasal administration of two doses of nanomicelles after a prime subcutaneous administration of BCG induced the highest mucosal and systemic immune responses.

Conclusion

Based on our results PEG-HspX/EsxS self-assembled nanomicelle is highly immunogenic and can be considered a potential vaccine candidate against Mtb to boost BCG efficiency.

Identification of Serum Cytokine Biomarkers Associated with Multidrug Resistant Tuberculosis (MDR-TB)

Existing tools (including GeneXpert) for diagnosis of multidrug resistant TB (MDR-TB) have limited utility when sputum samples for microbiological analyses cannot be obtained. There is the need for immunological biomarkers which could serve as putative diagnostic markers of MDR-TB. We measured and compared the serum cytokine levels of inflammatory cytokines (IFN-γ, TNF-α, IL12p70, IL-17A, granzyme B) and anti-inflammatory cytokines (IL-10, IL-6, IL-4) among MDR-TB, drug-susceptible (DS)-TB and healthy controls (no-TB) using the Human Magnetic Luminex Multiplex Immunoassay. Levels of IFN-γ and IL-4 were respectively 1.5 log lower and 1.9 log higher in MDR-TB compared to DS-TB cases. Moreover, IFN-γ, TNF-α, IL-10, IL-6, and IL-4 levels were significantly higher in individuals with MDR-TB and DS-TB cases compared to healthy controls. Pairs of cytokines, IL-4 and IFN-γ (p = 0.019), IL-4 and TNF (p = 0.019), and Granzyme B and TNF-α (p = 0.019), showed significant positive correlation in MDR-TB. Serum cytokine profiles can be exploited for immunodiagnostics, as made evident by the Interferon Gamma Release Assays (IGRAs) for TB infection. Using area under the curve values, no single or multiple cytokine combinations could discriminate between DS- and MDR-TB in this study. Studies with a larger sample size and more cytokines could better address the issue.

A T-Cell Epitope-Based Multi-Epitope Vaccine Designed Using Human HLA Specific T Cell Epitopes Induces a Near-Sterile Immunity against Experimental Visceral Leishmaniasis in Hamsters

Visceral leishmaniasis is a neglected tropical disease affecting 12 million people annually. Even in the second decade of the 21st century, it has remained without an effective vaccine for human use. In the current study, we designed three multiepitope vaccine candidates by the selection of multiple IFN-γ inducing MHC-I and MHC-II binder T-cell specific epitopes from three previously identified antigen genes of Leishmania donovani from our lab by an immuno-informatic approach using IFNepitope, the Immune Epitope Database (IEDB) T cell epitope identification tools, NET-MHC-1, and NET MHC-2 webservers. We tested the protective potential of these three multiepitope proteins as a vaccine in a hamster model of visceral leishmaniasis. The immunization data revealed that the vaccine candidates induced a very high level of Th1 biased protective immune response in-vivo in a hamster model of experimental visceral leishmaniasis, with one of the candidates inducing a near-sterile immunity. The vaccinated animals displayed highly activated monocyte macrophages with the capability of clearing intracellular parasites due to increased respiratory burst. Additionally, these proteins induced activation of polyfunctional T cells secreting INF-γ, TNF-α, and IL-2 in an ex-vivo stimulation of human peripheral blood mononuclear cells, further supporting the protective nature of the designed candidates.

Classical CD4 T cells as the cornerstone of antimycobacterial immunity

Tuberculosis is a significant health problem without an effective vaccine to combat it. A thorough understanding of the immune response and correlates of protection is needed to develop a more efficient vaccine. The immune response against Mycobacterium tuberculosis (Mtb) is complex and involves all aspects of the immune system, however, the optimal protective, non‐pathogenic T cell response against Mtb is still elusive. This review will focus on discussing CD4 T cell immunity against mycobacteria and its importance in Mtb infection with a primary focus on human studies. We will in particular discuss the large heterogeneity of immune cell subsets that have been revealed by recent immunological investigations at an unprecedented level of detail. These studies have identified specific classical CD4 T cell subsets important for immune responses against Mtb in various states of infection. We further discuss the functional attributes that have been linked to the various subsets such as upregulation of activation markers and cytokine production. Another important topic to be considered is the antigenic targets of Mtb‐specific immune responses, and how antigen reactivity is influenced by both disease state and environmental exposure(s). These are key points for both vaccines and immune diagnostics development. Ultimately, these factors are holistically considered in the definition and investigations of what are the correlates on protection and resolution of disease.

B-Cells and Antibodies as Contributors to Effector Immune Responses in Tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is still a major threat to mankind, urgently requiring improved vaccination and therapeutic strategies to reduce TB-disease burden. Most present vaccination strategies mainly aim to induce cell-mediated immunity (CMI), yet a series of independent studies has shown that B-cells and antibodies (Abs) may contribute significantly to reduce the mycobacterial burden. Although early studies using B-cell knock out animals did not support a major role for B-cells, more recent studies have provided new evidence that B-cells and Abs can contribute significantly to host defense against Mtb. B-cells and Abs exist in many different functional subsets, each equipped with unique functional properties. In this review, we will summarize current evidence on the contribution of B-cells and Abs to immunity toward Mtb, their potential utility as biomarkers, and their functional contribution to Mtb control.

Notch signaling pathway in infectious diseases: role in the regulation of immune response

BACKGROUND

The Notch signaling pathway is a cell signaling system that is conserved in a variety of eukaryotes. Overall, Notch receptors and their ligands are single-pass transmembrane proteins, which often require cell-cell interactions and proteolytic processing to promote signaling. Since its discovery, it has been the subject of extensive research that revealed its importance in several cellular mechanisms, including cell fate determination, hematopoiesis, tissue self-renewal, proliferation, and apoptosis during embryogenesis. Many studies have described the influence of the Notch pathway in modulating the innate and adaptive immune systems.

METHODS

We analyzed the literature on the role of the Notch pathway in regulating immune responses during infections, aiming to discuss the importance of establishing a Notch signaling pathway-based approach for predicting the outcome of infectious diseases.

CONCLUSION

In this review, we present an overview of evidence that demonstrates the direct and indirect effects of interaction between the Notch signaling pathway and the immune responses against bacterial, viral, fungal, and parasitic infections, as well as the importance of this pathway to predict the outcome of infectious diseases.

MicroRNA-23a-3p Down-Regulation in Active Pulmonary Tuberculosis Patients with High Bacterial Burden Inhibits Mononuclear Cell Function and Phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 Signaling via Targeting IRF1/SP1

The aim of this study is to explore the role of microRNAs (miR)-21/23a/146a/150/155 targeting the toll-like receptor pathway in active tuberculosis (TB) disease and latent TB infection (LTBI). Gene expression levels of the five miRs and predicted target genes were assessed in peripheral blood mononuclear cells from 46 patients with active pulmonary TB, 15 subjects with LTBI, and 17 non-infected healthy subjects (NIHS). THP-1 cell lines were transfected with miR-23a-3p mimics under stimuli with Mycobacterium TB-specific antigens. Both miR-155-5p and miR-150-5p gene expressions were decreased in the active TB group versus the NIHS group. Both miR-23a-3p and miR-146a-5p gene expressions were decreased in active TB patients with high bacterial burden versus those with low bacterial burden or control group (LTBI + NIHS). TLR2, TLR4, and interleukin (IL)10 gene expressions were all increased in active TB versus NIHS group. MiR-23a-3p mimic transfection reversed ESAT6-induced reduction of reactive oxygen species generation, and augmented ESAT6-induced late apoptosis and phagocytosis, in association with down-regulations of the predicted target genes, including tumor necrosis factor (TNF)-α, TLR4, TLR2, IL6, IL10, Notch1, IL6R, BCL2, TGF-β1, SP1, and IRF1. In conclusion, the down-regulation of miR-23a-3p in active TB patients with high bacterial burden inhibited mononuclear cell function and phagocytosis through TLR4/TNF-α/TGF-β1/IL-10 signaling via targeting IRF1/SP1.

Characterization of cytokine profile to distinguish latent tuberculosis from active tuberculosis and healthy controls

BACKGROUND

Tuberculosis (TB) is an infectious disease and its mortality rate ranks first. Latent tuberculosis infection (LTBI) means that a patient is infected with Mycobacterium tuberculosis, but has no relative clinical symptoms. It has been estimated that approximately 10% of patients with LTBI would develop into active tuberculosis. Therefore, it was urgent to search for more efficient biomarkers to discriminate LTBI from healthy population.

METHODS

The Luminex assay was employed to detect the quantity of cytokines secreted by mononuclear cells from peripheral blood stimulated with the ESAT6 protein among TB, LTBI and healthy controls. The cytokine profile was analyzed by principal components analysis and the receiver operating characteristic curve analysis.

RESULTS

The principal components analysis indicated that LTBI and TB were clearly separated from healthy controls, and that LTBI was also successfully differentiated from healthy controls. The cytokine profiling method to distinguish LTBI from healthy controls has a sensitivity and specificity of 100%. Nine potential biomarkers, including IL-23, IL-21, HGF, Bngf, IL-27, IL-31, IL-1β, IL-22 and IL-18, were identified, and these cytokines were considered as a potential cytokine complex for more effectively discriminating LTBI from healthy controls.

CONCLUSION

IL-23, IL-21, HGF, Bngf, IL-27, IL-31, IL-1β, IL-22 and IL-18 were demonstrated to be the potential cytokine complex for the assessment between LTBI and healthy controls.

7-oxo-DHEA enhances impaired M. tuberculosis-specific T cell responses during HIV-TB coinfection

BACKGROUND

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), affecting approximately one third of the world's population. Development of an adequate immune response will determine disease progression or progress to chronic infection. Risk of developing TB among human immunodeficiency virus (HIV)-coinfected patients (HIV-TB) is 20-30 times higher than those without HIV infection, and a synergistic interplay between these two pathogens accelerates the decline in immunological functions. TB treatment in HIV-TB coinfected persons is challenging and it has a prolonged duration, mainly due to the immune system failure to provide an adequate support for the therapy. Therefore, we aimed to study the role of the hormone 7-oxo-dehydroepiandrosterone (7-OD) as a modulator of anti-tuberculosis immune responses in the context of HIV-TB coinfection.

METHODS

A cross-sectional study was conducted among HIV-TB patients and healthy donors (HD). We characterized the ex vivo phenotype of CD4 + T cells and also evaluated in vitro antigen-specific responses by Mtb stimulation of peripheral blood mononuclear cells (PBMCs) in the presence or absence of 7-OD. We assessed lymphoproliferative activity, cytokine production and master transcription factor profiles.

RESULTS

Our results show that HIV-TB patients were not able to generate successful anti-tubercular responses in vitro compared to HD, as reduced IFN-γ/IL-10 and IFN-γ/IL-17A ratios were observed. Interestingly, treatment with 7-OD enhanced Th1 responses by increasing Mtb-induced proliferation and the production of IFN-γ and TNF-α over IL-10 levels. Additionally, in vitro Mtb stimulation augmented the frequency of cells with a regulatory phenotype, while 7-OD reduced the proportion of these subsets and induced an increase in CD4 + T-bet+ (Th1) subpopulation, which is associated with clinical data linked to an improved disease outcome.

CONCLUSIONS

We conclude that 7-OD modifies the cytokine balance and the phenotype of CD4 + T cells towards a more favorable profile for mycobacteria control. These results provide new data to delineate novel treatment approaches as co-adjuvant for the treatment of TB.

Harnessing the Immunomodulatory Properties of Bacterial Ghosts to Boost the Anti-mycobacterial Protective Immunity

Tuberculosis (TB) pathogenesis is characterized by inadequate immune cell activation and delayed T cell response in the host. Recent immunotherapeutic efforts have been directed at stimulating innate immunity and enhancing interactions between antigen presenting cells and T cells subsets to improve the protective immunity against TB. In this study, we investigated the immunostimulatory properties of bacterial ghosts (BG) as a novel approach to potentiate the host immunity against mycobacterial infection. BG are intact cytoplasm-free Escherichia coli envelopes and have been developed as bacterial vaccines and adjuvant/delivery system in cancer immunotherapy. However, BG have yet to be exploited as immunopotentiators in the context of infectious diseases. Here, we showed that BG are potent inducers of dendritic cells (DC), which led to enhanced T cell proliferation and differentiation into effector cells. BG also induced macrophage activation, which was associated with enhanced nitric oxide production, a key anti-mycobacterial weapon. We further demonstrated that the immunostimulatory capability of BG far exceeds that of LPS and involves both TLR4-dependent and independent pathways. Consistently, BG treatment, but not LPS treatment, reduced the bacterial burden in infected mice, which correlated with increased influx of innate and adaptive effector immune cells and increased production of key cytokines in the lungs. Finally and importantly, enhanced bacilli killing was seen in mice co-administered with BG and second-line TB drugs bedaquiline and delamanid. Overall, this work paves the way for BG as potent immunostimulators that may be harnessed to improve mycobacteria killing at the site of infection.

Mycobacteria-Specific T Cells May Be Expanded From Healthy Donors and Are Near Absent in Primary Immunodeficiency Disorders

Mycobacterial Infections can be severe in patients with T-cell deficiency or phagocyte disorders, and treatment is frequently complicated by antimicrobial resistance. Restoration of T-cell immunity via stem cell transplantation facilitates control of mycobacterial infections, but presence of active infections during transplantation is associated with a higher risk of mortality. Adoptive T cell immunotherapy has been successful in targeting viruses, but has not been attempted to treat mycobacterial infections. We sought to expand and characterize mycobacterial-specific T-cells derived from healthy donors in order to determine suitability for adoptive immunotherapy. Mycobacteria-specific T-cells (MSTs) were generated from 10 healthy donors using a rapid ex vivo expansion protocol targeting five known mycobacterial target proteins (AG85B, PPE68, ESXA, ESXB, and ADK). MSTs were compared to T-cells expanded from the same donors using lysate from M. tuberculosis or purified protein derivative from M. avium (sensitin). MST expansion from seven patients with primary immunodeficiency disorders (PID) and two patients with IFN-γ autoantibodies and invasive M. avium infections. MSTs expanded from healthy donors recognized a median of 3 of 5 antigens, with production of IFN-γ, TNF, and GM-CSF in CD4⁺ T cells. Comparison of donors who received BCG vaccine (n = 6) to those who did not (n = 4) showed differential responses to PPE68 (p = 0.028) and ADK (p = 0.015) by IFN-γ ELISpot. MSTs expanded from lysate or sensitin also recognized multiple mycobacterial antigens, with a statistically significant differences noted only in the response to PPE68 (p = 0.016). MSTs expanded from patients with primary immunodeficiency (PID) and invasive mycobacterial infections showed activity against mycobacterial antigens in only two of seven subjects, whereas both patients with IFN-γ autoantibodies recognized mycobacterial antigens. Thus, MSTs can be generated from donors using a rapid expansion protocol regardless of history of BCG immunization. Most tested PID patients had no detectable T-cell immunity to mycobacteria despite history of infection. MSTs may have clinical utility for adoptive immunotherapy in T-cell deficient patients with invasive mycobacterial infections.

Asthma and atopy prevalence are not reduced among former tuberculosis patients compared with controls in Lima, Peru

Background

Although there are theoretical reasons for believing that asthma and atopy may be negatively correlated with tuberculosis, epidemiological studies have had conflicting findings.

Objective

To determine if people with confirmed tuberculosis were less likely to be atopic and less likely to have atopic disease including asthma compared to those with no previous tuberculosis.

Methods

Patients in Lima, Peru with a prior history of tuberculosis were identified from clinic records in this cohort study. A representative sample of individuals without a prior tuberculosis diagnosis was recruited from the same community. Allergen skin prick testing was performed to classify atopic status. Allergic rhinitis was identified by history. Asthma was defined by symptoms and spirometry. Eosinophilic airway inflammation was measured using exhaled nitric oxide levels.

Results

We evaluated 177 patients with, and 161 individuals without, previous tuberculosis. There was a lower prevalence of atopy among people with prior tuberculosis on univariate analysis (odds ratio 0.57; 95% confidence interval 0.37–0.88) but, after adjustment for potential confounders, this was no longer statistically significant (aOR 0.64, 95% CI 0.41–1.01). The prevalence of allergic rhinitis (aOR 0.76, 95% CI 0.47 to 1.24 and asthma (aOR 1.18, 95% CI 0.69 to 2.00) did not differ significantly between the two groups. We also found no significant difference in the prevalence of elevated exhaled nitric oxide (aOR 1.30, 95% CI 0.78 to 2.17) or a combined index of atopic disease (aOR 0.86, 95% CI 0.54 to 1.36).

Conclusion

In this urban environment in a middle-income country, prior tuberculosis may be associated with a reduced risk of atopy but does not protect against asthma and atopic disease.

Cordyceps sinensis may inhibit Th22 cell chemotaxis to improve kidney function in lgA nephropathy

IgA nephropathy is the most common form of primary glomerulonephritis and an important cause of kidney failure. Cordyceps sinensis (CS) is a parasitic fungus that has a long history of use in Chinese medicine for the treatment of nephritis. Interleukin (IL)-22-producing helper T cells (Th22 cells) have been reported to be involved in lgA nephropathy. Th22 cells link the immune response to tissue inflammation. To elucidate the possible efficacy and mechanisms by which CS counteracts nephritis, we established an IgA nephropathy model in 6-week-old female BALB/c mice. The mice were randomly separated into 3 groups, the normal control, IgA nephropathy and CS (5 mg/kg/d) treatment groups. The Th22 cell frequencies and the relative pathological and cytokine changes were measured with flow cytometry, whereas the serum chemokine ligand 27 (CCL27) and IL-22 concentrations were detected with ELISA. The Th22 cell frequency decreased after 1 month of CS therapy. Additionally, mesangial cell proliferation decreased. Moreover, the chemokine receptor type 10 (CCR10), CCL27 and IL-22 expression levels were significantly reduced. In conclusion, CS may modulate the chemotaxis of Th22 cells to suppress inflammatory responses in IgA nephropathy.

Down-regulation of Notch signaling pathway reverses the Th1/Th2 imbalance in tuberculosis patients

Th1/Th2 imbalance to Th2 is of significance in the peripheral immune responses in Tuberculosis (TB) development. However, the mechanisms for Th1/Th2 imbalance are still not well determined. Notch signaling pathway is involved in the peripheral T cell activation and effector cell differentiation. However, whether it affects Th1/Th2 imbalance in TB patients is still not known. Here, we used γ-secretase inhibitor (DAPT) to treat the peripheral blood mononuclear cells (PBMCs) from healthy people or individuals with latent or active TB infection in vitro, respectively. Then, the Th1/Th2 ratios were determined by flow cytometry, and cytokines of IFN-γ, IL-4, IL-10 in the culture supernatant were measured by CBA method. The Notch signal pathway associated proteins Hes1, GATA3 and T-bet were quantitated by real-time PCR or immunoblotting. Our results showed that DAPT effectively inhibited the protein level of Hes1. In TB patients, the Th2 ratio increased in the PBMCs, alone with the high expression of GATA3 and IL-4, resulting in the high ratios of Th2/Th1 and GATA3/T-bet in TB patients. However, Th2 cells ratio decreased after blocking the Notch signaling pathway by DAPT and the Th2/Th1 ratio in TB patients were DAPT dose-dependent, accompanied by the decrease of IL-4 and GATA3. But, its influence on Th1 ratio and Th1 related T-bet and IFN-γ levels were not significant. In conclusion, our results suggest that blocking Notch signaling by DAPT could inhibit Th2 responses and restore Th1/Th2 imbalance in TB patients.

CD137 is a Useful Marker for Identifying CD4+ T Cell Responses to Mycobacterium tuberculosis

Upregulation of CD137 on recently activated CD8⁺ T cells has been used to identify rare viral and tumour antigen-specific T cells from the peripheral blood. We aimed to evaluate the accuracy of CD137 for identifying Mycobacterium tuberculosis (Mtb)-reactive CD4⁺ T cells in the peripheral blood of infected individuals by flow cytometry and to investigate the characteristics of these CD137⁺ CD4⁺ T cells. We initially enrolled 31 active tuberculosis (TB) patients, 31 individuals with latent TB infection (LTBI) and 25 healthy donors. The intracellular CD137 and interferon-γ (IFN-γ) production by CD4⁺ T cells was simultaneously detected under unstimulated and CFP10-stimulated (culture filtrate protein 10, a Mtb-specific antigen) conditions. In unstimulated CD4⁺ T cells, we found that the CD137 expression in the TB group was significantly higher than that in the LTBI group. Stimulation with CFP10 largely increased the CD4⁺ T cell CD137 expression in both the TB and LTBI groups. After CFP10 stimulation, the frequency of CD137⁺ CD4⁺ T cells was higher than that of IFN-γ⁺ CD4⁺ T cells in both the TB and LTBI groups. Most of the CFP10-activated IFN-γ-secreting cells were CD137-positive, but only a small fraction of the CD137-positive cells expressed IFN-γ. An additional 20 patients with TB were enrolled to characterize the CD45RO⁺ CCR7⁺ , CD45RO⁺ CCR7^- and CD45RO^- subsets in the CD137⁺ CD4⁺ T cell populations. The Mtb-specific CD137⁺ CD4⁺ T cells were mainly identified as having an effector memory phenotype. In conclusion, CD137 is a useful marker that can be used for identifying Mtb-reactive CD4⁺ T cells by flow cytometry.

Striking the right immunological balance prevents progression of tuberculosis

INTRODUCTION

Tuberculosis (TB) caused by infection with Mycobacterium tuberculosis (Mtb) is a major burden for human health worldwide. Current standard treatments for TB require prolonged administration of antimycobacterial drugs leading to exaggerated inflammation and tissue damage. This can result in the reactivation of latent TB culminating in TB progression. Thus, there is an unmet need to develop therapies that would shorten the duration of anti-TB treatment and to induce optimal protective immune responses to control the spread of mycobacterial infection with minimal lung pathology.

FINDINGS

Granulomata is the hallmark structure formed by the organized accumulation of immune cells including macrophages, natural killer cells, dendritic cells, neutrophils, T cells, and B cells to the site of Mtb infection. It safeguards the host by containing Mtb in latent form. However, granulomata can undergo caseation and contribute to the reactivation of latent TB, if the immune responses developed to fight mycobacterial infection are not properly controlled. Thus, an optimal balance between innate and adaptive immune cells might play a vital role in containing mycobacteria in latent form for prolonged periods and prevent the spread of Mtb infection from one individual to another.

CONCLUSION

Optimal and well-regulated immune responses against Mycobacterium tuberculosis may help to prevent the reactivation of latent TB. Moreover, therapies targeting balanced immune responses could help to improve treatment outcomes among latently infected TB patients and thereby limit the dissemination of mycobacterial infection.

Suppressors of cytokine signaling in tuberculosis

Tuberculosis (TB), a global disease mainly infected by Mycobacterium tuberculosis, remains leading public health problem worldwide. Suppressors of cytokine signaling (SOCSs) play important roles in the protection against microbial infection. However, the relationship between members of the SOCS family and tuberculosis infection remains unclear. Using peripheral blood mononuclear cells, we investigated the mRNA expression profiles of SOCS subfamilies among active TB, latent tuberculosis infection (LTBI), and healthy individuals. Our results showed that active tuberculosis subjects had higher levels of SOCS-3 mRNA, lower expressions of SOCS-2, -4, -5, -6, -7, and cytokine-inducible SH2-containing protein-1 (CIS-1) mRNAs, but not SOCS-1 mRNA than healthy and LTBI subjects. In men, LTBI patients had lower SOCS-3 than healthy subjects, and active TB patients had lower levels of SOCS-4, -5, and CIS-1 mRNAs but higher levels of SOCS-3 mRNA than healthy subjects. In women, LTBI patients had lower SOCS-3 mRNA level than healthy subjects, and active TB patients had lower CIS-1 mRNA level than healthy subjects. In non-aged adults (< 65 years old), TB patients had higher SOCS-3 mRNA and lower levels of SOCS-2, -4, -5, -6, -7, and CIS-1 mRNAs; whereas, aged TB patients (≥ 65 years old) had lower levels of SOCS-5 and CIS-1 mRNAs. These data suggest that particular SOCS members and their correlative relationships allow discrimination of active TB from healthy and LTBI subjects.

Safety and Immunogenicity of the Recombinant Mycobacterium bovis BCG Vaccine VPM1002 in HIV-Unexposed Newborn Infants in South Africa

Tuberculosis is a global threat to which infants are especially vulnerable. Effective vaccines are required to protect infants from this devastating disease. VPM1002, a novel recombinant Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine previously shown to be safe and immunogenic in adults, was evaluated for safety in its intended target population, namely, newborn infants in a region with high prevalence of tuberculosis. A total of 48 newborns were vaccinated intradermally with VPM1002 (n = 36) or BCG Danish strain (n = 12) in a phase II open-labeled, randomized trial with a 6-month follow-up period. Clinical and laboratory measures of safety were evaluated during this time. In addition, vaccine-induced immune responses to mycobacteria were analyzed in whole-blood stimulation and proliferation assays. The safety parameters and immunogenicity were comparable in the two groups. Both vaccines induced interleukin-17 (IL-17) responses; however, VPM1002 vaccination led to an increase of CD8+ IL-17+ T cells at the week 16 and month 6 time points. The incidence of abscess formation was lower for VPM1002 than for BCG. We conclude that VPM1002 is a safe, well-tolerated, and immunogenic vaccine in newborn infants, confirming results from previous trials in adults. These results strongly support further evaluation of the safety and efficacy of this vaccination in larger studies. (This study has been registered at ClinicalTrials.gov under registration no. NCT01479972.).

Th9 cytokines response and its possible implications in the immunopathogenesis of leprosy

AIMS

Leprosy is an infectious-contagious disease whose clinical evolution depends on the interaction of the infectious agent with the immune response of the host, leading to a clinical spectrum that ranges from lepromatous leprosy (susceptibility, LL) to tuberculoid leprosy (resistance, TT). The immune response profile will depend on the pattern of cytokine production and on the activity of macrophages during infection. Classically, the clinical evolution of leprosy has been associated with Th1/Th2 cytokine profiles, but the role of new cytokine profiles such as T helper 9 (Th9) remains to be elucidated.

METHODS

To evaluate the tissue expression profile of these cytokines, a cross-sectional study was conducted using a sample of 30 leprosy skin lesion biopsies obtained from patients with leprosy, 16 TT and 14 lepromatous LL.

RESULTS

Immunohistochemical analysis revealed a significant difference in interleukin (IL)-9, IL-4 transforming growth factor (TGF)-β and IL-10 levels between the two groups. IL-9 was more expressed in TT lesions compared with LL lesions. Higher expression of IL-4, IL-10 and TGF-β was observed in LL compared with TT. IL-4, IL-10 and TGF-β tended to be negatively correlated with the expression of IL-9, indicating a possible antagonistic activity in tissue.

CONCLUSIONS

The results suggest that Th9 lymphocytes may be involved in the response to Mycobacterium leprae, positively or negatively regulating microbicidal activity of the local immune system in the disease.

Identification of promising plasma immune biomarkers to differentiate active pulmonary tuberculosis

Although much research has been done related to biomarker discovery for tuberculosis infection, a set of biomarkers that can discriminate between active and latent TB diseases remains elusive. In the current study we correlate clinical aspects of TB disease with changes in the immune response as determined by biomarkers detected in plasma. Our study measured 18 molecules in human plasma in 17 patients with active disease (APTB), 14 individuals with latent tuberculosis infection (LTBI) and 16 uninfected controls (CTRL). We found that active tuberculosis patients have increased plasma levels of IL-6, IP-10, TNF-α, sCD163 and sCD14. Statistical analysis of these biomarkers indicated that simultaneous measurement of sCD14 and IL-6 was able to diagnose active tuberculosis infection with 83% accuracy. We also demonstrated that TNF-α and sCD163 were correlated with tuberculosis severity. We showed that the simultaneous detection of both plasma sCD14 and IL-6 is a promising diagnostic approach to identify APTB, and further, measurement of TNF-α and sCD163 can identify the most severe cases of tuberculosis.