Elevated chemokine levels in bronchoalveolar lavage fluid of tuberculosis patients

Monocytes predict prognosis and successful treatment in older patients with miliary tuberculosis

Background

The increasing number of patients with miliary tuberculosis (MTB) is a concern in an aging society because of its high mortality rate. Several prognostic biomarkers for MTB have been identified; however, the predictive ability of monocytes as biomarkers remains unknown. This study demonstrates the usefulness of monocytes as prognostic biomarkers for MTB.

Materials and methods

We retrospectively compared the clinical findings of 52 patients with MTB hospitalized between April 2013 and October 2021. The predictive ability of biomarkers for 3-month prognosis and their cutoff values were calculated. Survival times and longitudinal changes in monocytes after initiating treatment were compared.

Results

A smaller number of monocytes (#M), higher lymphocyte-monocyte ratio (LMR), higher neutrophil-monocyte ratio, and poorer performance status were associated with death within 3 months. #M was an independent prognostic factor. #M and LMR exhibited the highest predictive performance compared to others using receiver operating characteristic curve analysis (area under the curve = 0.86 and 0.85, respectively). Survival time was shorter in patients with #M ≤ 200 cells/μL and LMR > 2.5. Rapidly increasing #M after treatment was related to better prognosis in patients with #M ≤ 200 cells/μL at diagnosis.

Conclusions

#M at diagnosis and longitudinal changes in monocytes are related to MTB prognosis.

Multiple cytokine analysis based on QuantiFERON-TB gold plus in different tuberculosis infection status: an exploratory study

BACKGROUND

More efficient and convenient diagnostic method is a desperate need to reduce the burden of tuberculosis (TB). This study explores the multiple cytokines secretion based on QuantiFERON-TB Gold Plus (QFT-Plus), and screens for optimal cytokines with diagnostic potential to differentiate TB infection status.

METHODS

Twenty active tuberculosis (ATB) patients, fifteen patients with latent TB infection (LTBI), ten patients with previous TB and ten healthy controls (HC) were enrolled. Whole blood samples were collected and stimulated by QFT-Plus TB1 and TB2 antigens. The levels of IFN-γ, TNF-α, IL-2, IL-6, IL-5, IL-10, IP-10, IL-1Ra, CXCL-1 and MCP-1 in supernatant were measured by Luminex bead-based multiplex assays. The receiver operating characteristic curve was used to evaluate the diagnostic accuracy of cytokine for distinguishing different TB infection status.

RESULTS

After stimulation with QFT-Plus TB1 and TB2 antigens, the levels of all cytokines, except IL-5 in TB2 tube, in ATB group were significantly higher than that in HC group. The levels of IL-1Ra concurrently showed the equally highest AUC for distinguishing TB infection from HC, followed by the levels of IP-10 in both TB1 tube and TB2 tube. Moreover, IP-10 levels displayed the largest AUC for distinguishing ATB patients from non-ATB patients. Meanwhile, the levels of IP-10 also demonstrated the largest AUC in both TB1 tube and TB2 tube for distinguishing ATB patients from LTBI.

CONCLUSIONS

In addition to conventional detection of IFN-γ, measuring IP-10 and IL-1Ra based on QFT-Plus may have the more tremendous potential to discriminate different TB infection status.

Effect of teriparatide on drug treatment of tuberculous spondylitis: an experimental study

Tuberculous spondylitis often develops catastrophic bone destruction with uncontrolled inflammation. Because anti-tuberculous drugs do not have a role in bone formation, a combination drug therapy with a bone anabolic agent could help in fracture prevention and promote bone reconstruction. This study aimed to investigate the influence of teriparatide on the effect of anti-tuberculous drugs in tuberculous spondylitis treatment. We used the virulent Mycobacterium tuberculosis (Mtb) H37Rv strain. First, we investigated the interaction between teriparatide and anti-tuberculosis drugs (isoniazid and rifampin) by measuring the minimal inhibitory concentration (MIC) against H37Rv. Second, we evaluated the therapeutic effect of anti-tuberculosis drugs and teriparatide on our previously developed in vitro tuberculous spondylitis model of an Mtb-infected MG-63 osteoblastic cell line using acid-fast bacilli staining and colony-forming unit counts. Selected chemokines (interleukin [IL]-8, interferon γ-induced protein 10 kDa [IP-10], monocyte chemoattractant protein [MCP]-1, and regulated upon activation, normal T cell expressed and presumably secreted [RANTES]) and osteoblast proliferation (alkaline phosphatase [ALP] and alizarin red S [ARS] staining) were measured. Teriparatide did not affect the MIC of isoniazid and rifampin. In the Mtb-infected MG-63 spondylitis model, isoniazid and rifampin treatment significantly reduced Mtb growth, and cotreatment with teriparatide did not change the anti-tuberculosis effect of isoniazid (INH) and rifampin (RFP). IP-10 and RANTES levels were significantly increased by Mtb infection, whereas teriparatide did not affect all chemokine levels as inflammatory markers. ALP and ARS staining indicated that teriparatide promoted osteoblastic function even with Mtb infection. Cotreatment with teriparatide and the anti-tuberculosis drugs activated bone formation (ALP-positive area increased by 705%, P = 0.0031). Teriparatide was effective against Mtb-infected MG63 cells without the anti-tuberculosis drugs (ARS-positive area increased by 326%, P = 0.0037). Teriparatide had no effect on the efficacy of anti-tuberculosis drugs and no adverse effect on the activity of Mtb infection in osteoblasts. Furthermore, regulation of representative osteoblastic inflammatory chemokines was not changed by teriparatide treatment. In the in vitro Mtb-infected MG-63 cell model of tuberculous spondylitis, cotreatment with the anti-tuberculosis drugs and teriparatide increased osteoblastic function.

Human Pulmonary Tuberculosis: Understanding the Immune Response in the Bronchoalveolar System

Mycobacterium tuberculosis, the causal agent of one of the most devastating infectious diseases worldwide, can evade or modulate the host immune response and remain dormant for many years. In this review, we focus on identifying the local immune response induced in vivo by M. tuberculosis in the lungs of patients with active tuberculosis by analyzing data from untouched cells from bronchoalveolar lavage fluid (BALF) or exhaled breath condensate (EBC) samples. The most abundant resident cells in patients with active tuberculosis are macrophages and lymphocytes, which facilitate the recruitment of neutrophils. The cellular response is characterized by an inflammatory state and oxidative stress produced mainly by macrophages and T lymphocytes. In the alveolar microenvironment, the levels of cytokines such as interleukins (IL), chemokines, and matrix metalloproteinases (MMP) are increased compared with healthy patients. The production of cytokines such as interferon (IFN)-γ and IL-17 and specific immunoglobulin (Ig) A and G against M. tuberculosis indicate that the adaptive immune response is induced despite the presence of a chronic infection. The role of epithelial cells, the processing and presentation of antigens by macrophages and dendritic cells, as well as the role of tissue-resident memory T cells (Trm) for in situ vaccination remains to be understood.

Stimulated expression of ELR+ chemokines, VEGFA and TNF-AIP3 promote mycobacterial dissemination in extrapulmonary tuberculosis patients and Cavia porcellus model of tuberculosis

Pathogenic mycobacteria induce and accelerate blood vessel formation driven by extensive inflammation during granuloma formation, which is a central feature of mycobacterial pathogenesis. Tumor necrosis factor-alpha (TNF-α) enhances the expression of vascular endothelial growth factor (VEGF) and glutamic acid-leucine-arginine (ELR+) chemokines, which are potent inducers of vascularization. Most of the reported research work contends that VEGF growth factor induces neovascularization in human tuberculosis (TB) patients, but the evidence is inconclusive. Considerable ambiguity exists concerning the factors responsible for miliary tuberculosis. To identify such factors, we proposed an alternative explanation that could be found in miliary tuberculosis (MTB) cases. We performed a comparative analysis of angiogenic factors TNF-α, VEGF, and angiogenic ELR+ CXC and CC chemokine ligands in extrapulmonary tuberculosis (EPTB) and pulmonary tuberculosis (PTB) patients. To observe the relationship of these factors with the severity of bacterial burden, guinea pigs were infected with Mycobacterium tuberculosis (M.tb) and levels of the angiogenic factors were examined at different time intervals. Expression of these factors also exhibited a significant positive correlation with bacterial burden in other organs like the spleen, liver, and lymph nodes. We demonstrated statistical data on bacterial burden at different time points following the dissemination of infection in guinea pigs. In this study, we observed that there was a stimulated increase in the expression of ELR+ chemokines and VEGF in EPTB patients as compared to PTB patients. Following increased dissemination, the host immune response clears bacteria from the lungs during disease progression in guinea pigs.

Transcriptomic Analysis of Mycobacterium leprae-Stimulated Response in Peripheral Blood Mononuclear Cells Reveal Potential Biomarkers for Early Diagnosis of Leprosy

We aimed to identify an unique host transcriptional signature in peripheral blood mononuclear cells (PBMCs) in response to Mycobacterium leprae antigens to distinguish between patients with leprosy and non-leprosy controls for early diagnosis of the disease. Sixteen individuals were enrolled in the discovery cohort [eight patients with leprosy, comprising four multibacillary (MB) and four paucibacillary (PB); and eight non-leprosy controls, comprising four healthy house contacts (HHCs) and four endemic controls (ECs)]. The differences in the transcriptome response of PBMCs to M. leprae sonicate antigen were evaluated between leprosy patients and non-leprosy controls, and 12 differentially expressed genes (CCL2/MCP-1, IL-8, JAKM, ATP, ND1, SERP, FLJ10489, LINC00659, LOC34487, LOC101928143, MIR22, and NCF1C) were identified. The accuracy of the 12 differentially expressed genes was further validated for the diagnosis of leprosy using real-time quantitative PCR in 82 individuals (13 MB, 10 PB, 37 HHCs, and 22 ECs) in the validation cohort. We found that a 5 gene signature set IL-8, CCL2/MCP-1, SERP, LINC00659 and FLJ10489 had a suitable performance in discriminating leprosy from ECs. In addition, elevated expression of IL-8, CCL2/MCP-1, SERP and LINC00659 was associated with MB diagnosis compared with ECs, whereas increased expression of IL-8, CCL2/MCP-1, SERP and FLJ10489 was found to be useful biomarkers for PB diagnosis from ECs. Moreover, we found decreased expression of NCF1C among leprosy patients could distinguish leprosy from HHCs, whereas higher expression of CCL2 among MB than PB could distinguish different leprosy patients. In conclusion, among the 12 candidate host genes identified, a three gene signature IL-8, CCL2/MCP-1, and SERP showed the best performance in distinguishing leprosy patients from healthy controls. These findings may have implications for developing a rapid blood-based test for early diagnosis of leprosy.

MCP-1: Function, regulation, and involvement in disease

MCP-1 (Monocyte chemoattractant protein-1), also known as Chemokine (CC-motif) ligand 2 (CCL2), is from family of CC chemokines. It has a vital role in the process of inflammation, where it attracts or enhances the expression of other inflammatory factors/cells. It leads to the advancement of many disorders by this main mechanism of migration and infiltration of inflammatory cells like monocytes/macrophages and other cytokines at the site of inflammation. MCP-1 has been inculpated in the pathogenesis of numerous disease conditions either directly or indirectly like novel corona virus, cancers, neuroinflammatory diseases, rheumatoid arthritis, cardiovascular diseases. The elevated MCP-1 level has been observed in COVID-19 patients and proven to be a biomarker associated with the extremity of disease along with IP-10. This review will focus on involvement and role of MCP-1 in various pathological conditions.

The protective action of piperlongumine against mycobacterial pulmonary tuberculosis in its mitigation of inflammation and macrophage infiltration in male BALB/c mice

Introduction

Piperlongumine (PL) is a bioactive alkaloid and medicinal compound of piperamide isolated from the long pepper (Piper longum Linn). It has demonstrated bactericidal action against Mycobacterium tuberculosis (MTB), the cause of pulmonary tuberculosis; nevertheless, immunomodulatory activity had not been identified for it in MTB-triggered granulomatous inflammation. This study investigated if piperlongumine could inhibit such inflammation.

Material and Methods

Mycobacterium tuberculosis strain H37Rv was subjected to a broth microdilution assay. Piperlongumine at 5, 15, and 25 μg/mL, 0.2% dimethyl sulphoxide as control or 4 μM of dexamethasone were tested in vitro on MH-S murine alveolar macrophages. BALB/c mice were orally administered PL at 50, 100 and 150 mg/kg b.w. after trehalose-6,6-dimycolate (TDM) stimulation. Chemokine and cytokine concentrations were determined in lung supernatants. Flow cytometry and Western blot analysis were performed to determine phosphorylated spleen tyrosine kinase (Syk), c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) pathways.

Results

Piperlongumine inhibited inflammatory mediators and adherence of lymphocyte function-associated antigen 1 to MH-S cells following TDM activation. It also improved macrophage clearance of MTB. In TDM-stimulated MH-S cells, PL significantly influenced the macrophage inducible Ca²⁺-dependent lectin receptor (Mincle)-Syk-ERK signalling pathway. Oral dosing of PL effectively suppressed the development of pulmonary granulomas and inflammatory reactions in the TDM-elicited mouse granuloma model.

Conclusion

PL as an inhibitor of MTB-triggered granulomatous inflammation may be an effective complementary treatment for mycobacterial infection.

TLR-9 Plays a Role in Mycobacterium leprae-Induced Innate Immune Activation of A549 Alveolar Epithelial Cells

The respiratory tract is considered the main port of entry of Mycobacterium leprae, the causative agent of leprosy. However, the great majority of individuals exposed to the leprosy bacillus will never manifest the disease due to their capacity to develop protective immunity. Besides acting as a physical barrier, airway epithelium cells are recognized as key players by initiating a local innate immune response that orchestrates subsequent adaptive immunity to control airborne infections. However, to date, studies exploring the interaction of M. leprae with the respiratory epithelium have been scarce. In this work, the capacity of M. leprae to immune activate human alveolar epithelial cells was investigated, demonstrating that M. leprae-infected A549 cells secrete significantly increased IL-8 that is dependent on NF-κB activation. M. leprae was also able to induce IL-8 production in human primary nasal epithelial cells. M. leprae-treated A549 cells also showed higher expression levels of human β-defensin-2 (hβD-2), MCP-1, MHC-II and the co-stimulatory molecule CD80. Furthermore, the TLR-9 antagonist inhibited both the secretion of IL-8 and NF-κB activation in response to M. leprae, indicating that bacterial DNA sensing by this Toll-like receptor constitutes an important innate immune pathway activated by the pathogen. Finally, evidence is presented suggesting that extracellular DNA molecules anchored to Hlp, a histone-like protein present on the M. leprae surface, constitute major TLR-9 ligands triggering this pathway. The ability of M. leprae to immune activate respiratory epithelial cells herein demonstrated may represent a very early event during infection that could possibly be essential to the generation of a protective response.

Decitabine Promotes Modulation in Phenotype and Function of Monocytes and Macrophages That Drive Immune Response Regulation

Decitabine is an approved hypomethylating agent used for treating hematological malignancies. Although decitabine targets altered cells, epidrugs can trigger immunomodulatory effects, reinforcing the hypothesis of immunoregulation in treated patients. We therefore aimed to evaluate the impact of decitabine treatment on the phenotype and functions of monocytes and macrophages, which are pivotal cells of the innate immunity system. In vitro decitabine administration increased bacterial phagocytosis and IL-8 release, but impaired microbicidal activity of monocytes. In addition, during monocyte-to-macrophage differentiation, treatment promoted the M2-like profile, with increased expression of CD206 and ALOX15. Macrophages also demonstrated reduced infection control when exposed to Mycobacterium tuberculosis in vitro. However, cytokine production remained unchanged, indicating an atypical M2 macrophage. Furthermore, when macrophages were cocultured with lymphocytes, decitabine induced a reduction in the release of inflammatory cytokines such as IL-1β, TNF-α, and IFN-γ, maintaining IL-10 production, suggesting that decitabine could potentialize M2 polarization and might be considered as a therapeutic against the exacerbated immune response.

IL-1RA in the supernatant of QuantiFERON-TB Gold In-Tube and QuantiFERON-TB Gold Plus is useful for discriminating active tuberculosis from latent infection

INTRODUCTION

The new-generation QuantiFERON (QFT)-TB Gold Plus (QFT-Plus) is expected to be useful because it includes a new peptide that is supposed to induce a CD8⁺ T cell response. There is a need for a new marker with sensitivity higher than that of the conventional IFN-γ release assays owing to false-negative results in the latter. This study aimed to compare cytokines in QFT-plus and QuantiFERON-Gold In-Tube (QFT-GIT) supernatants to discriminate between active tuberculosis and latent tuberculosis infection (LTBI).

METHODS

A cross-sectional study was conducted at Tokyo National Hospital, wherein 21 LTBI patients and age and sex-matched active TB patients were randomly selected. The levels of various cytokines were measured and compared using the MAGPIX System, and receiver operating characteristic (ROC) curves were generated.

RESULTS

IL-1RA, IFN-γ, CXCL10/IP-10, and CCL4/MIP-1β levels were higher in the active TB group than in the LTBI group in QFT-GIT antigen (GIT Ag) tubes. In QFT-plus tubes, IL-1RA was higher in TB1 and TB2 tubes, while CCL2/MCP-1 was higher only in TB2 tubes. In Nil tubes, CCL5/RANTES, TNF-α, PDGF-BB, and IL-2 levels were significantly higher in the active TB group. IL-1RA in GIT Ag tubes showed the highest area under the curve of 0.8367. The sensitivity and specificity of IL-1RA were 66.7% (95% confidence interval [CI]: 43.0-85.4) and 90.5% (95% CI: 69.6-98.8), respectively, which were the highest among the cytokines.

CONCLUSIONS

IL-1RA level in the QFT-GIT supernatant can be a good marker for discriminating active TB from LTBI.

Defective MyD88 and IRAK4 but not TLR-2 expression in HIV+ individuals with latent tuberculosis infection

HIV infection markedly increases the likelihood of latent tuberculosis infection progressing to active TB. Information on expression of TLR-2, myeloid differentiation factor (MyD88), IL-1R- associated kinase-4 (IRAK4) and nuclear factor kappa B (NF-kB) in HIV+LTBI+ and HIV+ patients with active TB disease is limited. We found significantly higher percentages of CD14+TLR2+ cells in PBMCs of HIV+LTBI+ patients compared to HIV-LTBI+ individuals. γ-irradiated Mtb was unable to induce MyD88, IRAK4 expression and IL-1β, MCP-1, IP-10 production in HIV+LTBI+ patients. Pleural fluids from HIV+TB+ patients had low IL-1β, MCP-1, IP-10 and high IL-10, TNF-α production. γ-irradiated Mtb stimulated CD14+ cells from HIV+TB+ patients had low IL-1β, MCP-1, IP-10 production and MyD88, IRAK4 and similar NF-kB expression compared to those from of HIV-TB+ patients. Our results suggest defective MyD88, IRAK4 but not NF-kB inhibit IL-1β, MCP-1 and IP-10 production by CD14+ cells of HIV+ individuals with LTBI and active TB disease in peripheral blood and at the site of disease.

Sophora flavescens protects against mycobacterial Trehalose Dimycolate-induced lung granuloma by inhibiting inflammation and infiltration of macrophages

The immune system responds to Mycobacterium tuberculosis (MTB) infection by forming granulomas to quarantine the bacteria from spreading. Granuloma-mediated inflammation is a cause of lung destruction and disease transmission. Sophora flavescens (SF) has been demonstrated to exhibit bactericidal activities against MTB. However, its immune modulatory activities on MTB-mediated granulomatous inflammation have not been reported. In the present study, we found that flavonoids from Sophora flavescens (FSF) significantly suppressed the pro-inflammatory mediators released from mouse lung alveolar macrophages (MH-S) upon stimulation by trehalose dimycolate (TDM), the most abundant lipoglycan on MTB surface. Moreover, FSF reduced adhesion molecule (LFA-1) expression on MH-S cells after TDM stimulation. Furthermore, FSF treatment on TDM-activated lung epithelial (MLE-12) cells significantly downregulated macrophage chemoattractant protein (MCP-1/CCL2) expression, which in turn reduced the in vitro migration of MH-S to MLE-12 cells. In addition, FSF increased the clearance of mycobacterium bacteria (Mycobacterium aurum) in macrophages. FSF mainly affected the Mincle-Syk-Erk signaling pathway in TDM-activated MH-S cells. In TDM-induced mouse granulomas model, oral administration with FSF significantly suppressed lung granulomas formation and inflammation. These findings collectively implicated an anti-inflammatory role of FSF on MTB-mediated granulomatous inflammation, thereby providing evidence of FSF as an efficacious adjunct treatment during mycobacterial infection.

Mycobacterium tuberculosis Cell Wall Fragments Released upon Bacterial Contact with the Human Lung Mucosa Alter the Neutrophil Response to Infection

In 2016, the World Health Organization reported that one person dies of tuberculosis (TB) every 21 s. A host environment that Mycobacterium tuberculosis (M.tb) finds during its route of infection is the lung mucosa bathing the alveolar space located in the deepest regions of the lungs. We published that human lung mucosa, or alveolar lining fluid (ALF), contains an array of hydrolytic enzymes that can significantly alter the M.tb surface during infection by cleaving off parts of its cell wall. This interaction results in two different outcomes: modifications on the M.tb cell wall surface and release of M.tb cell wall fragments into the environment. Typically, one of the first host immune cells at the site of M.tb infection is the neutrophil. Neutrophils can mount an extracellular and intracellular innate immune response to M.tb during infection. We hypothesized that exposure of neutrophils to ALF-induced M.tb released cell wall fragments would prime neutrophils to control M.tb infection better. Our results show that ALF fragments activate neutrophils leading to an increased production of inflammatory cytokines and oxidative radicals. However, neutrophil exposure to these fragments reduces production of chemoattractants (i.e., interleukin-8), and degranulation, with the subsequent reduction of myeloperoxidase release, and does not induce cytotoxicity. Unexpectedly, these ALF fragment-derived modulations in neutrophil activity do not further, either positively or negatively, contribute to the intracellular control of M.tb growth during infection. However, secreted products from neutrophils primed with ALF fragments are capable of regulating the activity of resting macrophages. These results indicate that ALF-induced M.tb fragments could further contribute to the control of M.tb growth and local killing by resident neutrophils by switching on the total oxidative response and limiting migration of neutrophils to the infection site.

Cytokines and Chemokines in Mycobacterium tuberculosis Infection

Chemokines and cytokines are critical for initiating and coordinating the organized and sequential recruitment and activation of cells into Mycobacterium tuberculosis-infected lungs. Correct mononuclear cellular recruitment and localization are essential to ensure control of bacterial growth without the development of diffuse and damaging granulocytic inflammation. An important block to our understanding of TB pathogenesis lies in dissecting the critical aspects of the cytokine/chemokine interplay in light of the conditional role these molecules play throughout infection and disease development. Much of the data highlighted in this review appears at first glance to be contradictory, but it is the balance between the cytokines and chemokines that is critical, and the "goldilocks" (not too much and not too little) phenomenon is paramount in any discussion of the role of these molecules in TB. Determination of how the key chemokines/cytokines and their receptors are balanced and how the loss of that balance can promote disease is vital to understanding TB pathogenesis and to identifying novel therapies for effective eradication of this disease.

Primary mouse lung fibroblasts help macrophages to tackle Mycobacterium tuberculosis more efficiently and differentiate into myofibroblasts up on bacterial stimulation

Keeping with their classical role in wound healing, fibroblasts of the lung take part in the resolution of tubercular granulomas. They are totally absent in nascent granulomas, but surround necrotizing granulomas, and are the majority of cells in healed granulomas. Lung fibroblasts may become infected with Mycobacterium tuberculosis (Mtb). Two previous studies suggested an immunomodulatory effect of fibroblasts on infected macrophages. In the present study, we looked at the role of primary mouse lung fibroblasts on naive or activated mouse bone marrow macrophages infected with Mtb and the effect of infection on fibroblast properties. We observed that with fibroblasts in the vicinity, infected naive macrophages restricted the bacterial growth, while activated macrophages turned more bactericidal with concomitant increase in nitrite production. Neutralizing IL-1α in fibroblast supernatant reduced the nitrite production by infected macrophages. Secretion of IL-6 and MCP-1 was down-regulated, while TNF-α was up-regulated in infected naive macrophages. In infected activated macrophages, the secretion of IL-6 was up-regulated, while that of MCP-1 and TNF-α was unaffected. The 'fibroblast effects' were enhanced when the fibroblasts too were infected. Mtb induced IL-1 secretion and pro-fibrotic responses by fibroblasts. Mtb-induced myofibroblast conversion was blocked by rapamycin suggesting cell signalling via mTOR.

Impaired CXCR1-dependent oxidative defence in active tuberculosis patients

Much of the pronounced host inflammatory response that occurs in tuberculosis (TB) is related to failed immunity against the invading pathogen. The G-protein coupled receptors CXCR1 and CXCR2 are implicated in important signal transduction pathways in lung inflammatory responses. We investigated the expression and function of these receptors in a simple whole blood model from 24 patients with pulmonary TB and in subjects with latent TB infection (LTBI). Healthy controls were recruited from close contacts to the pulmonary index patients. We found that pulmonary TB patients had significantly increased CXCR1 expression on blood cells compared to LTBI subjects and controls (p < 0.001). In contrast, LTBI subjects had a significant increase in CXCR2 expression compared to pulmonary TB patients (p < 0.001) and controls (p < 0.01). Leukocyte function, measured as oxidative capacity, was decreased in pulmonary TB patients compared to LTBI and controls (p < 0.001) and correlated with the increased CXCR1 expression. Leukocyte recruitment, measured as the expression of microRNA-223 was increased in pulmonary TB patients compared to LTBI (p < 0.05). We found that variations in receptor expression are linked to disease progression and affect the immune response against Mycobacterium tuberculosis (Mtb).

Binding of CXCL8/IL-8 to Mycobacterium tuberculosis Modulates the Innate Immune Response

Interleukin-8 (IL-8) has been implicated in the pathogenesis of several human respiratory diseases, including tuberculosis (TB). Importantly and in direct relevance to the objectives of this report quite a few findings suggest that the presence of IL-8 may be beneficial for the host. IL-8 may aid with mounting an adequate response during infection with Mycobacterium tuberculosis (M. tb); however, the underlying mechanism remains largely unknown. The major goal of our study was to investigate the contribution of IL-8 to the inflammatory processes that are typically elicited in patients with TB. We have shown for the first time that IL-8 can directly bind to tubercle bacilli. We have also demonstrated that association of IL-8 with M. tb molecules leads to the augmentation of the ability of leukocytes (neutrophils and macrophages) to phagocyte and kill these bacilli. In addition, we have shown that significant amount of IL-8 present in the blood of TB patients associates with erythrocytes. Finally, we have noted that IL-8 is the major chemokine responsible for recruiting T lymphocytes (CD3(+), CD4(+), and CD8(+) T cells). In summary, our data suggest that the association of IL-8 with M. tb molecules may modify and possibly enhance the innate immune response in patients with TB.

Importance of reciprocal balance of T cell immunity in Mycobacterium abscessus complex lung disease

Background

Little is known about the nature of the host immune response to Mycobacterium abscessus complex (MABC) infection. The aim of the present study was to investigate whether alterations in serum immunomolecule levels after treating MABC lung disease patients with antibiotics can reflect the disease-associated characteristics.

Methods

A total of 22 immunomolecules in 24 MABC lung disease patients before and after antibiotic therapy were quantitatively analyzed using a multiplex bead-based system.

Results

In general, the pre-treatment levels of T helper type 1 (Th1)-related cytokines, i.e., interferon (IFN)-γ and interleukin (IL)-12, and Th2-related cytokines, i.e., IL-4 and IL-13, were significantly decreased in patients compared with control subjects. In contrast, the pre-treatment levels of Th17-related cytokines, i.e., IL-17 and IL-23, were significantly increased in MABC patients. Interestingly, significantly higher levels of IFN-γ-induced protein (IP)-10 and monokine induced by IFN-γprotein (MIG) were detected in patients with failure of sputum conversion at post-treatment compared to patients with successful sputum conversion.

Conclusion

Reduced Th1 and Th2 responses and enhanced Th17 responses in patients may perpetuate MABC lung disease, and the immunomolecules IP-10 and MIG, induced through IFN-γ, may serve as key markers for indicating the treatment outcome.

NF-κB repressing factor downregulates basal expression and mycobacterium tuberculosis induced IP-10 and IL-8 synthesis via interference with NF-κB in monocytes

Background

Our previous study showed NF-κB repressing factor (NKRF) downregulates IP-10 and IL-8 synthesis in the peripheral blood mononuclear cells and alveolar macrophages of TB patients with high bacterial loads. However, the mechanism underlying the repressive effect of NKRF is not fully understood.

Results

The levels of IP-10, IL-8 and NKRF were significantly up-regulated in THP-1 cells treated with heated mycobacterium tuberculosis (H. TB). NKRF inhibited NF-κB-mediated IP-10 and IL-8 synthesis and release induced by H. TB. The repressive effect of NKRF is mediated via interference with NF-κB (p65) binding and RNA polymerase II recruitment to promoter sites of IP-10 and IL-8.

Conclusions

We have elucidated that direct contact with MTb induces IP-10, IL-8 and a concomitant increase in NKRF in THP-1 cells. The up-regulated NKRF serves as an endogenous repressor for IP-10 and IL-8 synthesis to hinder host from robust response to MTb infection.

NF-κB repressing factor inhibits chemokine synthesis by peripheral blood mononuclear cells and alveolar macrophages in active pulmonary tuberculosis

NF-κB repressing factor (NRF) is a transcriptional silencer implicated in the basal silencing of specific NF-κB targeting genes, including iNOS, IFN-β and IL-8/CXCL8. IP-10/CXCL10 and IL-8/CXCL8 are involved in neutrophil and lymphocyte recruitment against M. tuberculosis (MTb) and disease progression of pulmonary tuberculosis (TB). Alveolar macrophages (AM) and peripheral blood mononuclear cells (PBMC) were used to study the regulatory role of NRF in pulmonary TB. AM and PBMC were purified from 19 TB patients and 15 normal subjects. To study the underlying mechanism, PBMC were exposed to heated TB bacilli. The regulation role of NRF in IP-10/CXCL10 and IL-8/CXCL8 was determined by NRF knock-down or over-expression. NRF binding capabilities in promoter sites were measured by chromatin immunoprecipitation (ChIP) assay. The levels of IP-10/CXCL10, IL-8/CXCL8 and NRF were significantly higher in AM and PBMC in patients with active TB. NRF played an inhibitory role in IP-10/CXCL10 and IL-8/CXCL8 inductions. We delineate the role of NRF in pulmonary TB, which inhibits the expressions of IP-10/CXCL10 and IL-8/CXCL8 in AM and PBMC of patients with high bacterial load. NRF may serve as an endogenous repressor to prevent robust increase in IP-10/CXCL10 and IL-8/CXCL8 when TB bacterial load is high.

Early secreted antigenic target of 6 kDa (ESAT-6) protein of Mycobacterium tuberculosis induces interleukin-8 (IL-8) expression in lung epithelial cells via protein kinase signaling and reactive oxygen species

Early secreted antigenic target of 6 kDa (ESAT-6) of Mycobacterium tuberculosis is critical for the virulence and pathogenicity of M. tuberculosis. IL-8, a major chemotactic cytokine for neutrophils and T lymphocytes, plays important roles in the development of lung injury. To further understand the role of ESAT-6 in lung pathology associated with tuberculosis development, we studied the effects of ESAT-6 on the regulation of IL-8 expression in lung epithelial cells. ESAT-6 induced IL-8 expression by increasing IL-8 gene transcription and mRNA stability. ESAT-6 induction of IL-8 promoter activity was dependent on nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) binding and sensitive to pharmacological inhibition of PKC and ERK and p38 MAPK pathways. ESAT-6 activated ERK and p38 MAPK phosphorylation and rapidly induced reactive oxygen species (ROS) production. Dimethylthiourea but not mannitol inhibited IL-8 induction by ESAT-6, further supporting the involvement of ROS in the induction of IL-8 expression. Exposure of mice to ESAT-6 induced localized inflammatory cell aggregate formation with characteristics of early granuloma concomitant with increased keratinocyte chemoattractant CXCL1 staining in bronchiolar and alveolar type II epithelial cells and alveolar macrophages. Our studies have identified a signal transduction pathway involving ROS, PKC, ERK, and p38 MAPKs and NF-κB and AP-1 in the ESAT-6 induction of IL-8 expression in lung epithelial cells. This has important implications for the understanding of lung innate immune responses to tuberculosis and the pathogenesis of lung injury in tuberculosis.

Immunomodulation of alveolar epithelial cells by Mycobacterium tuberculosis phosphatidylinositol mannosides results in apoptosis

During intracellular residence in macrophages, mycobacterial lipids, namely phosphatidylinositol mannosides (PIM) and lipoarabinomannans, are expelled in the lung milieu to interact with host cells. PIM include a group of essential lipid components of Mycobacterium tuberculosis (M. tb) cell wall. Given that PIM function as mycobacterial adhesins for binding to host cells, the present study explored the consequences of interaction of M. tb PIM with alveolar epithelial cells (AEC). A 24-h PIM exposure at a concentration of 10 μg/mL to AEC conferred cytolysis to AEC via induction of apoptosis, suggesting their potential to alter alveolar epithelium integrity. The results also reflected that type I like AEC are more sensitive to cytolysis than type II AEC. PIM-treated AEC exhibited significant production of reactive oxygen species (ROS) and an immunosuppressive cytokine transforming growth factor-β (TGF-β) in the culture supernatants. Although AEC displayed constitutive mRNA transcripts for toll-like receptors (TLR2 and 4) as well as chemokines (IL-8 and MCP-1), no significant change in their expression was observed upon PIM treatment. Collectively, these results offer insights into PIM potential as M. tb virulence factor that might promote mycobacterial dissemination by causing cytolysis of AEC via increased production of ROS and TGF-β.

Macrophages in tuberculosis: friend or foe

Tuberculosis (TB) remains one of the greatest threats to human health. The causative bacterium, Mycobacterium tuberculosis (Mtb), is acquired by the respiratory route. It is exquisitely human adapted and a prototypic intracellular pathogen of macrophages, with alveolar macrophages (AMs) being the primary conduit of infection and disease. The outcome of primary infection is most often a latently infected healthy human host, in whom the bacteria are held in check by the host immune response. Such individuals can develop active TB later in life with impairment in the immune system. In contrast, in a minority of infected individuals, the host immune response fails to control the growth of bacilli, and progressive granulomatous disease develops, facilitating spread of the bacilli via infectious aerosols coughed out into the environment and inhaled by new hosts. The molecular details of the Mtb-macrophage interaction continue to be elucidated. However, it is clear that a number of complex processes are involved at the different stages of infection that may benefit either the bacterium or the host. Macrophages demonstrate tremendous phenotypic heterogeneity and functional plasticity which, depending on the site and stage of infection, facilitate the diverse outcomes. Moreover, host responses vary depending on the specific characteristics of the infecting Mtb strain. In this chapter, we describe a contemporary view of the behavior of AMs and their interaction with various Mtb strains in generating unique immunologic lung-specific responses.

Chemokines shape the immune responses to tuberculosis

Mycobacterium tuberculosis (Mtb) is the intracellular pathogen that causes the disease, tuberculosis. Chemokines and chemokine receptors are key regulators in immune cell recruitment to sites of infection and inflammation. This review highlights our recent advances in understanding the role of chemokines and chemokine receptors in cellular recruitment of immune cells to the lung, role in granuloma formation and host defense against Mtb infection.

Different patterns of cytokines and chemokines combined with IFN-γ production reflect Mycobacterium tuberculosis infection and disease

BACKGROUND

IFN-γ is presently the only soluble immunological marker used to help diagnose latent Mycobacterium tuberculosis (M.tb) infection. However, IFN-γ is not available to distinguish latent from active TB infection. Moreover, extrapulmonary tuberculosis, such as tuberculous pleurisy, cannot be properly diagnosed by IFN-γ release assay. As a result, other disease- or infection-related immunological biomarkers that would be more effective need to be screened and identified.

METHODOLOGY

A panel of 41 soluble immunological molecules (17 cytokines and 24 chemokines) was tested using Luminex liquid array-based multiplexed immunoassays. Samples, including plasma and pleural effusions, from healthy donors (HD, n = 12) or patients with latent tuberculosis infection (LTBI, n = 20), pulmonary tuberculosis (TB, n = 12), tuberculous pleurisy (TP, n = 15) or lung cancer (LC, n = 15) were collected and screened for soluble markers. Peripheral blood mononuclear cells (PBMCs) and pleural fluid mononuclear cells (PFMCs) were also isolated to investigate antigen-specific immune factors.

PRINCIPAL FINDINGS

For the 41 examined factors, our results indicated that three patterns were closely associated with infection and disease. (1) Significantly elevated plasma levels of IL-2, IP-10, CXCL11 and CXCL12 were present in both patients with tuberculosis and in a sub-group participant with latent tuberculosis infection who showed a higher level of IFN-γ producing cells by ELISPOT assay compared with other latently infected individuals. (2) IL-6 and IL-9 were only significantly increased in plasma from active TB patients, and the two factors were consistently highly secreted after M.tb antigen stimulation. (3) When patients developed tuberculous pleurisy, CCL1, CCL21 and IL-6 were specifically increased in the pleural effusions. In particular, these three factors were consistently highly secreted by pleural fluid mononuclear cells following M.tb-specific antigen stimulation. In conclusion, our data imply that the specific secretion of soluble immunological factors, in addition to IFN-γ, may be used to evaluate M.tb infection and tuberculosis disease.

Immune responses in the lungs of patients with tuberculous pleural effusion without pulmonary tuberculosis

Background

Tuberculous pleural effusion (TPE) is one of the most common forms of extrapulmonary tuberculosis. Because most studies of TPE focused on the pleural space, little information regarding lung parenchyma is available. We therefore aimed to investigate immune responses in the lung parenchyma of TPE patients without pulmonary tuberculosis.

Methods

Patients with any evidence of pulmonary tuberculosis, either from radiologic or bacteriologic evaluation, were excluded. Bronchoalveolar lavage fluid (BALF) was collected from 10 newly diagnosed, untreated, HIV-negative TPE patients and 10 healthy controls. We analyzed T-lymphocyte subpopulations and measured 10 cytokines in BALF. Cytokine levels in BALF were standardised using urea.

Results

The concentrations of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), and the CD4+/CD8+ ratio of T-lymphocytes were significantly higher in TPE patients without pulmonary tuberculosis than in the controls. Of the cytokines measured in BALF, VEGF showed the highest concentration. No difference was observed in T-helper type 2 cytokines between the 2 groups.

Conclusion

There were significant immune responses and increases in IFN-γ, TNF-α, and VEGF in the lung parenchyma of TPE patients without pulmonary tuberculosis. This result suggests that TPE may induce a significant immune response in lung parenchyma.

Effect of vitamin D3 on chemokine expression in pulmonary tuberculosis

1,25 Dihydroxy vitamin D(3) (vitamin D(3)) is an immunomodulator and its deficiency has been associated with susceptibility to tuberculosis. We have studied the immunoregulatory role of vitamin D(3) on various chemokine expression in pulmonary tuberculosis. Peripheral blood mononuclear cells obtained from 21 pulmonary tuberculosis (PTB) patients and 24 healthy controls (HCs) were cultured for 48 h with culture filtrate antigen (CFA) of Mycobacterium tuberculosis with or without vitamin D(3) at a concentration 1 × 10(-7)M. The relative mRNA expression of monocyte chemoattractant protein-1 (MCP-1, CCL2), macrophage inflammatory protein-1α (MIP-1α, CCL3), macrophage inflammatory protein-1β (MIP-1β, CCL4), and regulated upon-activation, normal T cell-expressed and secreted (RANTES, CCL5) and IFN-γ inducible protein-10 (IP-10, CXCL10) chemokines were estimated from 48 h old macrophages using real-time polymerase chain reaction (RT-PCR). The culture supernatants were used to estimate the various chemokines including monokine induced by IFN-γ (MIG, CXCL9) levels using cytometric bead array. In HCs, vitamin D(3) significantly suppressed the MCP-1 mRNA expression of CFA stimulated cells (p=0.0027), while no such effect was observed in PTB patients. Vitamin D(3) showed no significant effect on MIP-1α, MIP-1β and RANTES in both the study groups. The CFA induced IP-10 mRNA and protein expression was significantly suppressed by vitamin D(3) in both the study groups (p<0.05). A similar suppressive effect of vitamin D(3) was observed with MIG protein in healthy controls (p=0.0029) and a trend towards a suppression was observed in PTB patients. The suppressive effect of vitamin D(3) is more prominent in CXC chemokines rather than CC chemokines. This suggests that vitamin D(3) may down regulate the recruitment and activation of T-cells through CXC chemokines at the site of infection and may act as a potential anti-inflammatory agent.

Exosomes isolated from mycobacteria-infected mice or cultured macrophages can recruit and activate immune cells in vitro and in vivo

More than 2 billion people are infected with Mycobacterium. tuberculosis; however, only 5-10% of those infected will develop active disease. Recent data suggest that containment is controlled locally at the level of the granuloma and that granuloma architecture may differ even within a single infected individual. Formation of a granuloma likely requires exposure to mycobacterial components released from infected macrophages, but the mechanism of their release is still unclear. We hypothesize that exosomes, which are small membrane vesicles containing mycobacterial components released from infected macrophages, could promote cellular recruitment during granuloma formation. In support of this hypothesis, we found that C57BL/6 mouse-derived bone marrow macrophages treated with exosomes released from M. tuberculosis-infected RAW264.7 cells secrete significant levels of chemokines and can induce migration of CFSE-labeled macrophages and splenocytes. Exosomes isolated from the serum of M. bovis bacillus Calmette-Guérin-infected mice could also stimulate macrophage production of chemokines and cytokines ex vivo, but the level and type differed during the course of a 60-d infection. Of interest, the exosome concentration in serum correlated strongly with mouse bacterial load, suggesting some role in immune regulation. Finally, hollow fiber-based experiments indicated that macrophages treated with exosomes released from M. tuberculosis-infected cells could promote macrophage recruitment in vivo. Exosomes injected intranasally could also recruit CD11b(+) cells into the lung. Overall, our study suggests that exosomes may play an important role in recruiting and regulating host cells during an M. tuberculosis infection.

Correlation between lymph node pathology and chemokine expression during bovine tuberculosis

Bovine tuberculosis is a disease of worldwide importance yet comparatively little is known about chemokine responses to infection. We report on the levels of chemokine expression within lymph nodes of cattle infected with Mycobacterium bovis when infection would be well established. Expression levels of a number of chemokines were increased in infected cattle and could be correlated to levels of respective chemokine receptors. Several chemokines were significantly correlated to pathology within the lymph node, indicating a direct relationship between chemokine expression and disease. Vaccinated animals challenged with M. bovis had lower levels of chemokine expression than unvaccinated, challenged animals, correlating with lower levels of disease in vaccinated animals. The chemokine expression profile correlated with previous evidence for a pro-inflammatory bias within the lymph node. At this stage of infection we suggest there is on-going chemokine expression by cells associated with the granuloma and continual recruitment of cells to control infection.

LipC (Rv0220) is an immunogenic cell surface esterase of Mycobacterium tuberculosis

We have reported previously the identification of novel proteins of Mycobacterium tuberculosis by the immunoscreening of an expression library of M. tuberculosis genomic DNA with sera obtained from M. tuberculosis-infected rabbits at 5 weeks postinfection. In this study, we report the further characterization of one of these antigens, LipC (Rv0220). LipC is annotated as a member of the Lip family based on the presence of the consensus motif "GXSXG" characteristic of esterases. Although predicted to be a cytoplasmic enzyme, we provide evidence that LipC is a cell surface protein that is present in both the cell wall and the capsule of M. tuberculosis. Consistent with this localization, LipC elicits strong humoral immune responses in both HIV-negative (HIV-) and HIV-positive (HIV+) tuberculosis (TB) patients. The absence of anti-LipC antibodies in sera from purified protein derivative-positive (PPD+) healthy subjects confirms its expression only during active M. tuberculosis infection. Epitope mapping of LipC identified 6 immunodominant epitopes, 5 of which map to the exposed surface of the modeled LipC protein. The recombinant LipC (rLipC) protein also elicits proinflammatory cytokine and chemokine responses from macrophages and pulmonary epithelial cells. rLipC can hydrolyze short-chain esters with the carbon chain containing 2 to 10 carbon atoms. Together, these studies demonstrate that LipC is a novel cell surface-associated esterase of M. tuberculosis that is highly immunogenic and elicits both antibodies and cytokines/chemokines.

B lymphocytes that migrate to tuberculous pleural fluid via the SDF-1/CXCR4 axis actively respond to antigens specific for Mycobacterium tuberculosis

B-cell biology has been largely uncharacterized in the field of tuberculosis (TB). In this study, we investigated the immunophenotypical and functional characteristics of B cells obtained from the pleural fluid (PF) and peripheral blood of patients with tuberculous pleuritis (TP). Our results indicated that the total numbers of B cells, CD27(+) memory B cells and plasmablasts were clearly lower in the PF than in peripheral blood. Furthermore, we found significantly higher expression of CXCR4 on B cells in the PF, and a chemotaxis assay showed that B cells in the PF were more responsive to stromal cell-derived factor-1 (SDF-1) than B cells from peripheral blood. In addition, SDF-1 levels in PF were remarkably high compared with SDF-1 levels in plasma, suggesting that the SDF-1/CXCR4 axis might facilitate the migration of circulating B cells into tuberculous pleural space. Importantly, we observed that significantly more antibodies were produced by B cells in the PF following stimulation with BCG, early secretory antigenic target (ESAT-6)/culture filtrate protein-10 (CFP-10) or ESAT-6 protein. Collectively, these data demonstrate that Mycobacterium tuberculosis-specific B cells exist at local sites of infection in TP patients and this localization might influence the immune response to M. tuberculosis.

Polymorphisms in the RANTES gene increase susceptibility to active tuberculosis in Tunisia

RANTES plays a pivotal role in attracting and activating various leukocyte populations that control Mycobacterium tuberculosis infection. The present study investigated the relationship between the RANTES polymorphisms (-28C/G; rs2280788, and -403G/A; rs2107538) and susceptibility to active tuberculosis (TB) in Tunisian populations. A total of 168 patients with pulmonary TB (pTB), 55 with extrapulmonary TB (epTB), and 150 control subjects were studied. Genotype analyses were carried out using polymerase chain reaction-restriction fragment length polymorphism method. We found that the -28 GG genotype was significantly associated with susceptibility to pTB (odds ratio [OR]=11.19; 95% confidence intervals [CI], 5.14-25; P corrected for the number of genotypes [Pc]=10(-8)) and epTB (OR=11.67; 95% CI, 4.74-29.33; Pc=10(-8)). However, the -28 CC genotype was found to be significantly associated with resistance to pTB (OR=0.08; 95% CI, 0.04-0.16; Pc=10(-8)) and epTB development (OR=0.11; 95% CI, 0.05-0.27; Pc=10(-8)). -403A allele was associated with increased risk development of epTB (OR=2.21; 95% CI, 1.18-4.14; p=0.007). G-G and A-C haplotypes and the AG/GC diplotype were associated with increase susceptibility to pTB (OR=7.88, 95% CI, 5.38-11.55; Pc=3.10(-8); OR=2.32, 95% CI, 1.32-4.11; Pc=3.10(-3); OR=13.26, 95% CI, 6.06-29.89; Pc=3.10(-8); respectively) and epTB (OR=6.64, 95% CI, 4-11.05; Pc=3.10(-8); OR=2.6, 95% CI, 1.26-5.35; Pc=12.10(-3); OR=11.26, 95% CI, 4.44-29.28; Pc=3.10(-8); respectively). Collectively, our findings suggested an association of the RANTES -28C/G and -403G/A functional polymorphisms with susceptibility to Mycobacterium tuberculosis infection in Tunisian populations.

Reactive oxygen species-activated p38/ERK 1/2 MAPK signaling pathway in the Mycobacterium bovis bacillus Calmette Guérin (BCG)-induced CCL2 secretion in human monocytic cell line THP-1

BACKGROUND AND AIMS

CCL2 plays an important role in mycobacterial infection by inducing leukocyte recruitment and activation. Here we assess the role of reactive oxygen species (ROS) in the secretion of the CCL2 and the activation of mitogen-activated protein kinases (MAPKs) by human monocytic cells infected with Mycobacterium bovis bacillus Calmette Guérin (BCG).

METHODS

CCL2 mRNA and protein expression were measured by reverse transcriptase polymerase chain reaction (RT-PCR), quantitative PCR and ELISA. Kinase phosphorylation was determined by immunoblotting.

RESULTS

Treatment of human monocytic cells with M. bovis BCG activated rapid superoxide generation. mRNA expression of CCL2 was increased in M. bovis BCG-infected monocytic cells, and this increase was abrogated by administration of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor diphenyleneiodonium (DPI). Importantly, M. bovis BCG-induced CCL2 protein secretion was also inhibited by the NADPH oxidase inhibitor DPI, the selective inhibitor of NADPH oxidase apocynin, the mitochondrial electron transfer chain subunit I inhibitor rotenone and H(2)O(2) scavenging enzyme catalase, indicating that the inhibition is through the NADPH/ROS pathway. Analysis of downstream signals showed that inhibition of NADPH oxidase inhibited M. bovis BCG-induced phosphorylation of MAPK (extracellular signal-regulated kinase (ERK) 1/2 and p38).

CONCLUSIONS

These results strongly suggest that NADPH oxidase-derived ROS-mediated activation of p38 and ERK 1/2 is essential for the M. bovis BCG-induced CCL2 production.

MCP-1 -2518 A/G functional polymorphism is associated with increased susceptibility to active pulmonary tuberculosis in Tunisian patients

Monocyte chemoattractant protein-1 (MCP-1) plays crucial role in protective immunity against Mycobacterium tuberculosis (MT). In this study, we examined whether single nucleotide polymorphism (SNP) -2518 A/G (rs 1024611) of MCP-1 affect the susceptibility to active tuberculosis (TB) in Tunisian populations. Genomic DNA from patients with active TB (168 cases of pulmonary TB and 55 cases of extrapulmonary TB) and ethnically controls (150 cases) was genotyped for the MCP-1 -2518 A/G SNP by polymerase chain reaction fragment length polymorphism (PCR-RFLP). We observed that -2518 G allele and GG genotype (high MCP-1 producer) frequencies were significantly more elevated in active pulmonary TB group in comparison to control group [34 vs. 22%; P = 0.0007; 15 vs. 5%, P corrected for the number of genotypes (Pc) = 0.015; respectively]. Additionally, they were associated with increased risk development of this clinical form of TB [odds ratio (OR) = 1.83, 95% confidence intervals (CI) = 1.26-2.66; OR = 3.1, 95% CI = 1.28-7.76; respectively]. However, wild type allele -2518 A and AA genotype were over-represented in control group (78 and 62%) and seem to be protective factors against TB. Moreover, -2518 AA genotype was more frequent in control group and was associated with resistance against development of active pulmonary TB (OR = 0.56, 95% CI = 0.35-0.89, Pc = 0.03). Our findings confirm the key role of -2518 A/G SNP of MCP-1 and support its association with resistance/susceptibility to the development of active pulmonary TB in the Tunisian population.

Mycobacterium Tuberculosis Infection and Inflammation: what is Beneficial for the Host and for the Bacterium?

Tuberculosis is still a major health problem in the world. Initial interactions between Mycobacterium tuberculosis and the host mark the pathway of infection and the subsequent host inflammatory response. This inflammatory response is tightly regulated by both the host and the bacterium during different stages of infection. As infection progresses, the initial intense pro-inflammatory response observed is regulated by suppressive mediators balancing inflammation. In this environment, M. tuberculosis battles to survive interfering with the host inflammatory response. In this review we discuss the major effector molecules involved in inflammation in relation to the different stages of M. tuberculosis infection.

CCL2 responses to Mycobacterium tuberculosis are associated with disease severity in tuberculosis

Background

Leucocyte activating chemokines such as CCL2, CCL3, and CXCL8 together with proinflammatory IFNγ, TNFα and downmodulatory IL10 play a central role in the restriction of M. tuberculosis infections, but is unclear whether these markers are indicative of tuberculosis disease severity.

Methodology

We investigated live M. tuberculosis- and M. bovis BCG- induced peripheral blood mononuclear cell responses in patients with tuberculosis (TB) and healthy endemic controls (ECs, n = 36). TB patients comprised pulmonary (PTB, n = 34) and extrapulmonary groups, subdivided into those with less severe localized extrapulmonary TB (L-ETB, n = 16) or severe disseminated ETB (D-ETB, n = 16). Secretion of CCL2, IFNγ, IL10 and CCL3, and mRNA expression of CCL2, TNFα, CCL3 and CXCL8 were determined.

Results

M. tuberculosis- and BCG- induced CCL2 secretion was significantly increased in both PTB and D-ETB (p<0.05, p<0.01) as compared with L-ETB patients. CCL2 secretion in response to M. tuberculosis was significantly greater than to BCG in the PTB and D-ETB groups. M. tuberculosis-induced CCL2 mRNA transcription was greater in PTB than L-ETB (p = 0.023), while CCL2 was reduced in L-ETB as compared with D-ETB (p = 0.005) patients. M. tuberculosis –induced IFNγ was greater in L-ETB than PTB (p = 0.04), while BCG-induced IFNγ was greater in L-ETB as compared with D-ETB patients (p = 0.036). TNFα mRNA expression was raised in PTB as compared with L-ETB group in response to M. tuberculosis (p = 0.02) and BCG (p = 0.03). Mycobacterium-induced CCL3 and CXCL8 was comparable between TB groups.

Conclusions

The increased CCL2 and TNFα in PTB patients may support effective leucocyte recruitment and M. tuberculosis localization. CCL2 alone is associated with severity of TB, possibly due to increased systemic inflammation found in severe disseminated TB or due to increased monocyte infiltration to lung parenchyma in pulmonary disease.

Relationship between circulating levels of IFN-gamma, IL-10, CXCL9 and CCL2 in pulmonary and extrapulmonary tuberculosis is dependent on disease severity

Protection against Mycobacterium tuberculosis infection is dependent on T cell and macrophage activation regulated by cytokines. Cytokines and chemokines produced at disease sites may be released into circulation. Data available on circulating cytokines in tuberculosis (TB) is mostly on pulmonary TB (PTB) with limited information on extrapulmonary disease (EPul-TB). We measured interferon-gamma (IFN-gamma), interkeukin-10 (IL-10), CXCL9 and CCL2 in sera of patients (n = 80) including; PTB (n = 42), EPul-TB (n = 38) and BCG vaccinated healthy endemic controls (EC, n = 42). EPul-TB patients comprised those with less severe (LNTB) or severe (SevTB) disease. Serum IFN-gamma, IL-10 and CXCL9 levels were significantly greater while CCL2 was reduced in TB patients as compared with EC. IFN-gamma was significantly greater in PTB as compared with LNTB (P = 0.002) and SevTB (P = 0.029). CXCL9 was greater in PTB as compared with LNTB (P = 0.009). In contrast, CCL2 levels were reduced in PTB as compared with LNTB (P = 0.021) and SevTB (P = 0.024). A Spearman's rank correlation analysis determined a positive association between IFN-gamma and IL-10 (rho = 0.473, P = 0.002) and IFN-gamma and CXCL9 (rho = 0.403, P = 0.008) in the PTB group. However, in SevTB, only IFN-gamma and CXCL9 were positively associated (rho = 0.529, P = 0.016). Systemic levels of cytokines are reflective of local responses at disease sites. Therefore, our data suggests that in PTB increased IFN-gamma and CXCL9 balanced by IL-10 may result in a more effective cell mediated response in the host. However, elevated inflammatory chemokines CXCL9 and CCL2 in severe EPul-TB without concomitant down modulatory cytokines may exacerbate disease related pathology and hamper restriction of M. tuberculosis infection.

Augmented chemokine levels and chemokine receptor expression on immune cells during pulmonary tuberculosis

The systemic changes in immune mediators such as cytokine and chemokines, and their synchronized interaction that regulates the cell trafficking during Mycobacterium tuberculosis (M. tuberculosis) infection, were studied. Cytokines and chemokines were evaluated by cytometric bead array (CBA) and enzyme-linked immunosorbent assay (ELISA) in 34 pulmonary tuberculosis (PTB) patients and 30 healthy subjects. The expression of chemokine receptors was assessed by flow cytometry. A significant increase in IP-10, MIG, interleukin-8, RANTES, and interleukin-6 levels was found, whereas a decrease in interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta was observed during PTB. Significant correlation within chemokines and between cytokines was observed in PTB. All immune cells except monocytes and B cells expressed significantly higher levels of CCR1, CCR2, and CXCR2 whereas CCR7 expression was upregulated only on monocytes and neutrophils in PTB. Both T and B cells expressed significantly high levels of CXCR3 which also correlated well with the chemokine levels in PTB. Thus, it was found that chemokines function coordinately and consistently during PTB. This balanced chemokine and cytokine relationship at the periphery may aid in amplified effector immune cell trafficking and retarded monocyte migration through differential chemokine receptor expression.

Expression and regulation of chemokines in mycobacterial infection

Chemokines are the key molecules that recruit immune cells by chemotaxis and act in leukocyte activation during mycobacterial diseases. Currently, tuberculosis is a leading infectious disease affecting millions of people worldwide. The purpose of this review is to describe a series of recent scientific evidence concerning to the protective role of some members of the CC- and the CXC chemokine subfamilies for the control of mycobacterial infection. The discussion will (1) highlight the effectiveness of some chemokines as potent immunoprophylactic tool for controlling the mycobacterial establishment within the host, (2) describe recent work on the relevance of cellular signaling pathways by which mycobacterial antigens mediate chemokine induction, and (3) summarize current progress in the understanding of the potential use of chemokines as potent adjuvants in antimycobacterial immune responses.

Mycobacterium tuberculosis antigens specifically modulate CCR2 and MCP-1/CCL2 on lymphoid cells from human pulmonary hilar lymph nodes

Macrophages and dendritic cells are involved in the immune response to Mycobacterium tuberculosis (Mtb). Such a response, although extensively studied using animal models and cells from human blood, has not been characterized in cells from pulmonary hilar lymph nodes (PHLN). We characterized populations of myeloid APC from PHLN and determined their expression of CCR2, CCR5, CCR7, CD40, CD54, CD80, and CD86 as well as the cytokine/chemokine microenvironment before and after purified protein derivative (PPD) and mannosilated lipoarabinomannan (ManLAM) stimulation. Results show that there are at least three APC populations in PHLN, defined as CD14highHLA-DRlow/-, CD14dimHLA-DRdim, and CD14-HLA-DRhigh/dendritic cells (DC), with the largest number represented by CD14dimHLA-DRdim cells (where dim indicates intermediate levels). CD14-HLA-DRhigh/DC expressed higher levels of costimulatory molecules and lower levels of CCR2 and CCR5, but all cell populations showed similar CCR7 levels. PPD and ManLAM specifically down-regulated CCR2 expression but not that of CCR5 and CCR7, and such down-regulation was observed on all APC populations. Mtb Ag did not affect the expression of costimulatory molecules. PPD but not ManLAM specifically induced MCP-1/CCL2 production, which was likely associated with the induction of IFN-gamma because this cytokine was highly induced by PPD. We characterized, for the first time, different APC from human PHLN and show that Mtb Ag exert fine and specific regulation of molecules closely associated with the immune response to Mtb infection. Because knowledge of this response in secondary lymphoid tissues is still poorly understood in humans, such studies are necessary and important for a better understanding of lymphoid cell microenvironment and migrating capacities and their role in the immunopathogenesis of tuberculosis.

HIV-1 protecting CCR5-Delta32 allele in medieval Poland

CCR5-Delta32 is the mutation in the chemokine receptor CCR5 that gives its homozygous carriers nearly complete protections from HIV-1 infection. Restricted almost exclusively to Europe, the mutation is thought to have originated in the continent and risen in frequency to the present-day value of approximately 10% due to a selective advantage it gave its carriers. The mutation bearing allele was initially calculated to be approximately 1000 years old and pandemic diseases, such as Bubonic Plague or smallpox were postulated to have selected it. However, new reports appear, that question these hypotheses. Data from ancient DNA (aDNA) studies prove the mutation to be much older, as suggested by calculations based on newer genetic maps. In order to investigate if the plagues of the last millennium selected the allele, and add to the discussion on CCR5-Delta32 origin and age, we searched for the mutation in aDNA isolated from individuals whose skeletal remains were collected at archaeological sites in Poland, dated back to 11-14th centuries. The calculated mean frequency of the allele in medieval Poland (5.06% as compared to contemporary 10.26%), implies its longer than previously believed presence in European populations, and suggests that historic pandemics had little effect on its present-day frequency.

Mycobacterium bovis bacillus Calmette-Guerin induces CCL5 secretion via the Toll-like receptor 2-NF-kappaB and -Jun N-terminal kinase signaling pathways

In response to Mycobacterium bovis bacillus Calmette-Guérin (BCG), CC chemokines are secreted from host cells to attract components of the innate and adaptive immune systems to the site of infection. Toll-like receptor 2 (TLR2) has been shown to recognize M. bovis BCG and to initiate signaling pathways that result in enhanced secretion of CC chemokines. Despite the essential requirement of TLR2 in M. bovis BCG infection, the mechanisms by which it induces secretion of CC chemokines are not well defined. In this study, we report that stimulation of HEK293 cells expressing human TLR2 with M. bovis BCG resulted in increased CCL2 and CCL5 secretion, as determined by an enzyme-linked immunosorbent assay. M. bovis BCG infection resulted in the activation of c-Jun N-terminal kinase (JNK), and the inhibition of JNK activity had a significant effect on M. bovis BCG-dependent CCL5 secretion in TLR2-expressing cells but no effect on M. bovis BCG-dependent CCL2 secretion from infected HEK293 cells expressing human TLR2. The M. bovis BCG-induced CCL5 release was attenuated by sulfasalazine (a well-described inhibitor of NF-kappaB activity), BAY 11-7082 (an IkappaB phosphorylation inhibitor), and ALLN (a well-described inhibitor of NF-kappaB activation that prevents degradation of IkappaB and eventually results in a lack of translocated NF-kappaB in the nucleus). In addition, stimulation of TLR2-expressing cells with M. bovis BCG resulted in translocation of NF-kappaB subunits from the cytoplasmic to the nuclear fraction, and stimulation of cells with M. bovis BCG activated IkappaB kinase alphabeta. These findings indicate that M. bovis BCG induces CCL5 production through mechanisms that include a TLR2-dependent component that requires JNK and NF-kappaB activities.