Plasma chemokines are biomarkers of disease severity, higher bacterial burden and delayed sputum culture conversion in pulmonary tuberculosis

Mycobacterium tuberculosis strain with deletions in menT3 and menT4 is attenuated and confers protection in mice and guinea pigs

The genome of Mycobacterium tuberculosis encodes for a large repertoire of toxin-antitoxin systems. In the present study, MenT3 and MenT4 toxins belonging to MenAT subfamily of TA systems have been functionally characterized. We demonstrate that ectopic expression of these toxins inhibits bacterial growth and this is rescued upon co-expression of their cognate antitoxins. Here, we show that simultaneous deletion of menT3 and menT4 results in enhanced susceptibility of M. tuberculosis upon exposure to oxidative stress and attenuated growth in guinea pigs and mice. We observed reduced expression of transcripts encoding for proteins that are essential or required for intracellular growth in mid-log phase cultures of ΔmenT4ΔT3 compared to parental strain. Further, the transcript levels of proteins involved in efficient bacterial clearance were increased in lung tissues of ΔmenT4ΔT3 infected mice relative to parental strain infected mice. We show that immunization of mice and guinea pigs with ΔmenT4ΔT3 confers significant protection against M. tuberculosis infection. Remarkably, immunization of mice with ΔmenT4ΔT3 results in increased antigen-specific TH1 bias and activated memory T cell response. We conclude that MenT3 and MenT4 are important for M. tuberculosis pathogenicity and strains lacking menT3 and menT4 have the potential to be explored further as vaccine candidates.

The levels of soluble CD137 are increased in tuberculosis patients and associated with disease severity and prognosis

Tuberculosis (TB) was the leading cause of death from a single infectious agent before the coronavirus pandemic. Therefore, it is important to search for severity biomarkers and devise appropriate therapies. A total of 139 pulmonary TB (PTB) patients and 80 healthy controls (HCs) were recruited for plasma soluble CD137 (sCD137) detection through ELISA. Moreover, pleural effusion sCD137 levels were measured in 85 TB patients and 36 untreated lung cancer patients. The plasma cytokine levels in 64 patients with PTB and blood immune cell subpopulations in 68 patients with PTB were analysed via flow cytometry. Blood sCD137 levels were higher in PTB patients (p = 0.012) and correlated with disease severity (p = 0.0056). The level of sCD137 in tuberculous pleurisy effusion (TPE) was markedly higher than that in malignant pleurisy effusion (p = 0.018). Several blood cytokines, such as IL-6 (p = 0.0147), IL-8 (p = 0.0477), IP-10 (p ≤ 0.0001) and MCP-1 (p = 0.0057), and some laboratory indices were significantly elevated in severe PTB (SE) patients, but the percentages of total lymphocytes (p = 0.002) and cytotoxic T cells (p = 0.036) were significantly lower in SE patients than in non-SE patients. In addition, the sCD137 level was negatively correlated with the percentage of total lymphocytes (p = 0.0008) and cytotoxic T cells (p = 0.0021), and PTB patients with higher plasma sCD137 levels had significantly shorter survival times (p = 0.0041). An increase in sCD137 is a potential biomarker for severe TB and indicates a poor prognosis.

Distinct TB-antigen stimulated cytokine profiles as predictive biomarkers for unfavorable treatment outcomes in pulmonary tuberculosis

Introduction

The assessment of tuberculosis (TB) treatment outcomes predominantly relies on sputum culture conversion status. To enhance treatment management, it is crucial to identify non-sputum-based biomarkers that can predict unfavorable outcomes. Cytokines are widely studied as diagnostic biomarkers for active TB. However, their potential as indicators for unfavorable treatment outcomes remains uncertain.

Methodology

This study was conducted within a well-characterized cohort comprising newly diagnosed patients with drug-sensitive pulmonary TB, confirmed through sputum smear and culture positivity. Our objective was to elucidate the TB antigen-stimulated cytokine profile at pre-treatment and at 2 months into anti-TB treatment (ATT) in patients with unfavorable treatment outcomes (cases, n = 27) in comparison to recurrence-free, microbiologically cured controls (n = 31). Whole blood was stimulated with TB antigens using the QuantiFERON In-tube gold method, and plasma supernatants were subjected to a panel of 14 cytokine measurements.

Results

In our study, pre-treatment analysis revealed that eight cytokines (IL-2, IFN-γ, TNF-α, IL-6, IL-10, IL-17A, IL-18, and GM-CSF) were significantly elevated at baseline in cases compared to cured controls, both in unstimulated conditions and following TB antigen (CFP10, ESAT6, and TB7.7) stimulation. A similar pattern was observed at the 2-month mark of ATT, with eight cytokines (IL-2, IL-10, IL-13, IFN-γ, IL-6, IL-12p70, IL-17A, and TNF-α) showing significant differences between the groups. Importantly, no variations were detected following mitogen stimulation, underscoring that these distinctive immune responses are primarily driven by TB-specific antigens.

Conclusion

Our findings indicate that individuals with unfavorable TB treatment outcomes display a characteristic cytokine profile distinct from TB-cured patients, even before commencing ATT. Therefore, the levels of specific cytokine pre-treatment and at the 2-month point in the course of treatment may serve as predictive immune markers for identifying individuals at risk of unfavorable TB treatment outcomes, with these responses being predominantly influenced by TB-specific antigens.

Effect of Metformin on systemic chemokine responses during anti-tuberculosis chemotherapy

BACKGROUND

Metformin (MET), by boosting immunity, has been suggested as a host-adjunctive therapy to anti-tuberculosis treatment (ATT).

METHODS

We evaluated whether adding MET to the standard ATT can alter the host chemokine response. We investigated the influence of metformin on the plasma levels of a wide panel of chemokines in a group of active tuberculosis patients before treatment, at 2nd month of ATT and at 6-months of ATT as part of our clinical study to examine the effect of metformin on ATT.

RESULTS

Our results demonstrated that addition of metformin resulted in diminished CC (CCL1 and CCL3) and CXC (CXCL-2 and CXCL-10) chemokines in MET arm as compared to non-MET arm at the 2nd month and 6th month of ATT. In addition to this, MET arm showed significantly diminished chemokines in individuals with high bacterial burden and cavitary disease.

CONCLUSION

Our current data suggest that metformin alters chemokines responses that could potentially curb excessive inflammation during ATT.

Immunopathology in human pulmonary tuberculosis: Inflammatory changes in the plasma milieu and impaired host immune cell functions

Host immune response is key for protection in tuberculosis, but the causative agent, Mycobacterium (M.) tuberculosis, manages to survive despite immune surveillance. Key mechanisms of immune protection have been identified, but the role of immunopathology in the peripheral blood of tuberculosis patients remains unclear. Tuberculosis immunopathology in the blood is characterised by patterns of immunosuppression and hyperinflammation. These seemingly contradictory findings and the pronounced heterogeneity made it difficult to interpret the results from previous studies and to derive implications of immunopathology. However, novel approaches based on comprehensive data analyses and revitalisation of an ancient plasma milieu in vitro assay connected inflammation with immunosuppressive factors in tuberculosis. Moreover, interrelations between the aberrant plasma milieu and immune cell pathology were observed. This review provides an overview of studies on changes in plasma milieu and discusses recent findings linking plasma factors to T-cell and monocyte/macrophage pathology in pulmonary tuberculosis patients.

A Review Of Host-Specific Diagnostic And Surrogate Biomarkers In Children With Pulmonary Tuberculosis

BACKGROUND

Tuberculosis (TB) is one of the most common causes of mortality globally with a steady rise in paediatric cases in the past decade. Laboratory methods of diagnosing TB and monitoring response to treatment have limitations. Current research focuses on interrogating host- and/or pathogen-specific biomarkers to address this problem.

METHODS

We reviewed the literature on host-specific biomarkers in TB to determine their value in diagnosis and treatment response in TB infected and HIV/TB co-infected children on anti-tuberculosis treatment.

RESULTS AND CONCLUSION

While no single host-specific biomarker has been identified for diagnosis or treatment responses in children, several studies suggest predictive biosignatures for disease activity. Alarmingly, current data on host-specific biomarkers for diagnosing and assessing anti-tuberculosis treatment in TB/HIV co-infected children is inadequate. Various factors affecting host-specific biomarker responses should be considered in interpreting findings and designing future studies within specific clinical settings.

Host Genetic Impact on Infectious Diseases among Different Ethnic Groups

Infectious diseases such as malaria, tuberculosis (TB), human immunodeficiency virus (HIV), and the coronavirus disease of 2019 (COVID-19) are problematic globally, with high prevalence particularly in Africa, attributing to most of the death rates. There have been immense efforts toward developing effective preventative and therapeutic strategies for these pathogens globally, however, some remain uncured. Disease susceptibility and progression for malaria, TB, HIV, and COVID-19 vary among individuals and are attributed to precautionary measures, environment, host, and pathogen genetics. While studying individuals with similar attributes, it is suggested that host genetics contributes to most of an individual's susceptibility to disease. Several host genes are identified to associate with these pathogens. Interestingly, many of these genes and polymorphisms are common across diseases. This paper analyzes genes and genetic variations within host genes associated with HIV, TB, malaria, and COVID-19 among different ethnic groups. The differences in host-pathogen interaction among these groups, particularly of Caucasian and African descent, and which gene polymorphisms are prevalent in an African population that possesses protection or risk to disease are reviewed. The information in this review could potentially help develop personalized treatment that could effectively combat the high disease burden in Africa.

Mycobacterium tuberculosis-specific memory T cells in bronchoalveolar lavage of patients with pulmonary tuberculosis

BACKGROUND

Mycobacterium tuberculosis(MTB) most often infects the lungs and results in pulmonary tuberculosis(TB). MTB-specific memory T cells are able to respond quickly against antigens and help reduce the burden of pulmonary bacteria. The characteristics, function and chemotaxis axis of memory T cells in the lung remain unclear. The current study aimed to clarify the classification, function and recruitment of local antigen-specific memory T cells in the lung and the periphery blood of patients with pulmonary TB.

METHODS

A total of 85 patients with active pulmonary TB were included in the study. Bronchoalveolar lavage fluid (BALF) and Peripheral blood were collected for further detection. The cell-surface markers and intracellular staining of memory T cell subtypes were measured by flow cytometry. The level of CXCL9, CXCL10 and CXCL11 in Bronchoalveolar lavage fluid cells and peripheral blood mononuclear cells (PBMC) were measured by Real-time PCR.

RESULTS

The ratio of effective Memory T cells (TEM) were the highest in BALF of patients with pulmonary TB. In patients, CXCR3 and its ligands was increased in memory T cells of BALF compared with PBMC. IFN-γ+TNF-α+ effective Memory T cells and central memory T cells from BALF were increased after antigen stimulation. CXCR3 was higher in IFN-γ+ compared with IFN-γ- in CD4+ TCM and TEM from BALF of patients. Compared with PBMC, the PD-1 levels of terminal effector memory RA+(TEMRA) and TEM cells in CD4+ memory T cells of BALF were significantly increased. In addition, PD-1 was increased in IFN-γ+ compared with IFN-γ- in CD4+TEM from BALF of patients. There was no difference in Treg ratio between PBMC and BALF of TB patients.

CONCLUSIONS

The CXCL9/CXCL11-CXCR3 axis may participate in the chemotaxis of memory T cells from the peripheral to lung. CD4+TEM and TEMRA in BALF may have exhausted, especially the cytokine producing TEM. Our study clarified the characteristics of antigen-specific memory T cells in local lung and may have impact on strategies of therapy and vaccine.

Tuberculosis-Associated Hemophagocytic Lymphohistiocytosis: A Review of Current Literature

Hemophagocytic lymphohistiocytosis (HLH) is a condition of immune dysregulation and hyperinflammation, leading to organ failure and death. Malignancy, autoimmune conditions, and infections, including Mycobacterium tuberculosis (TB), are all considered triggers of HLH. The aim of this study was to review all reported cases of TB-associated HLH in English literature, and to summarize the epidemiology, diagnostics, treatment, and mortality in patients with concomitant HLH and TB. A systematic review of described cases with TB-associated HLH, via a structured literature search in the medical database PubMed, is presented. Additional articles were included through cross-referencing with existing review articles. Articles were reviewed based on a predetermined set of criteria. A total of 116 patients with TB-associated HLH were identified with a male:female ratio of about 3:2. The age at presentation ranged from 12 days to 83 years. Malignancy, autoimmunity, and renal failure were the most common comorbid conditions. Most patients received both tuberculostatic and specific immunomodulating treatment, which was associated with a 66% (48/73) survival rate compared to 56% (15/27) in those receiving only tuberculostatic treatment, and 0% (0/13) in those receiving only immunomodulating treatment. The survival rate was 55% overall. The overlapping presentation between disseminated TB and HLH poses challenging diagnostics and may delay diagnosis and treatment, leading to increased mortality. TB should be considered as a potential trigger of HLH; clinicians' knowledge and awareness of this may result in the appropriate investigations needed to ensure diagnosis and proper treatment.

Effect of TB Treatment on Neutrophil-Derived Soluble Inflammatory Mediators in TB Patients with and without HIV Coinfection

The mycobacteriological analysis of sputum samples is the gold standard for tuberculosis diagnosis and treatment monitoring. However, sputum production can be challenging after the initiation of TB treatment. As a possible alternative, we therefore investigated the dynamics of neutrophil-derived soluble inflammatory mediators during TB treatment in relation to HIV ART status and the severity of lung impairment. Plasma samples of TB patients with (N = 47) and without HIV (N = 21) were analyzed at baseline, month 2, month 6 (end of TB treatment) and month 12. Plasma levels of MMP-1, MMP-8, MPO and S100A8 markedly decreased over the course of TB treatment and remained at similar levels thereafter. Post-TB treatment initiation, significantly elevated plasma levels of MMP-8 were detected in TB patients living with HIV, especially if they were not receiving ART treatment at baseline. Our data confirm that the plasma levels of neutrophil-based biomarkers can be used as candidate surrogate markers for TB treatment outcome and HIV-infection influenced MMP-8 and S100A8 levels. Future studies to validate our results and to understand the dynamics of neutrophils-based biomarkers post-TB treatment are needed.

Low body mass index is associated with diminished plasma cytokines and chemokines in both active and latent tuberculosis

Introduction

Low body mass index (BMI) is a major risk factor for tuberculosis (PTB). Low BMI can impair the immune system and thus might affect TB incidence.

Methods

We examined the plasma levels of Type 1, Type 17, pro-inflammatory, Type 2 and regulatory cytokines and CC and CXC chemokines in PTB and latent TB (LTB) individuals with low BMI (LBMI) or normal BMI (NBMI).

Results

Our data show that PTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL-17A, IL-6, IL-12, IL-4 and IL-5 cytokines but significantly higher levels of IL-10, TGFβ and GM-CSF in LBMI compared to NBMI. Similarly, PTB is also associated with significantly lower levels of CCL2, CCL3, CCL11, CXCL1, CXCL9 and CXCL10 chemokines in LBMI compared to NBMI. Our data reveals that LTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL1β, IL-12, IL-13 cytokines but significantly higher levels of IL-10, TGFβ, IL-4 and IL-22 in LBMI compared to NBMI. Similarly, LTB is also associated with significantly lower levels of CCL2, CXCL1, CXCL9 and CXCL10 and significantly higher levels of CCL1, CCL3, and CCL4 in LBMI compared to NBMI.

Conclusion

Thus, LBMI has a major impact on the cytokine and chemokine milieu of both PTB and LTB and might predispose to the increased risk of tuberculosis by this immunomodulatory effect.

Plasma chemokines CXCL10 and CXCL9 as potential diagnostic markers of drug-sensitive and drug-resistant tuberculosis

Tuberculosis (TB) diagnosis still remains to be a challenge with the currently used immune based diagnostic methods particularly Interferon Gamma Release Assay due to the sensitivity issues and their inability in differentiating stages of TB infection. Immune markers are valuable sources for understanding disease biology and are easily accessible. Chemokines, the stimulant, and the shaper of host immune responses are the vital hub for disease mediated dysregulation and their varied levels in TB disease are considered as an important marker to define the disease status. Hence, we wanted to examine the levels of chemokines among the individuals with drug-resistant, drug-sensitive, and latent TB compared to healthy individuals. Our results demonstrated that the differential levels of chemokines between the study groups and revealed that CXCL10 and CXCL9 as potential markers of drug-resistant and drug-sensitive TB with better stage discriminating abilities.

Advancing personalized medicine for tuberculosis through the application of immune profiling

While early and precise diagnosis is the key to eliminating tuberculosis (TB), conventional methods using culture conversion or sputum smear microscopy have failed to meet demand. This is especially true in high-epidemic developing countries and during pandemic-associated social restrictions. Suboptimal biomarkers have restricted the improvement of TB management and eradication strategies. Therefore, the research and development of new affordable and accessible methods are required. Following the emergence of many high-throughput quantification TB studies, immunomics has the advantages of directly targeting responsive immune molecules and significantly simplifying workloads. In particular, immune profiling has been demonstrated to be a versatile tool that potentially unlocks many options for application in TB management. Herein, we review the current approaches for TB control with regard to the potentials and limitations of immunomics. Multiple directions are also proposed to hopefully unleash immunomics' potential in TB research, not least in revealing representative immune biomarkers to correctly diagnose TB. The immune profiles of patients can be valuable covariates for model-informed precision dosing-based treatment monitoring, prediction of outcome, and the optimal dose prediction of anti-TB drugs.

Diagnosis and biomarkers for ocular tuberculosis: From the present into the future

Tuberculosis is an airborne disease caused by Mycobacterium tuberculosis (Mtb) and can manifest both pulmonary and extrapulmonary disease, including ocular tuberculosis (OTB). Accurate diagnosis and swift optimal treatment initiation for OTB is faced by many challenges combined with the lack of standardized treatment regimens this results in uncertain OTB outcomes. The purpose of this study is to summarize existing diagnostic approaches and recently discovered biomarkers that may contribute to establishing OTB diagnosis, choice of anti-tubercular therapy (ATT) regimen, and treatment monitoring. The keywords ocular tuberculosis, tuberculosis, Mycobacterium, biomarkers, molecular diagnosis, multi-omics, proteomics, genomics, transcriptomics, metabolomics, T-lymphocytes profiling were searched on PubMed and MEDLINE databases. Articles and books published with at least one of the keywords were included and screened for relevance. There was no time limit for study inclusion. More emphasis was placed on recent publications that contributed new information about the pathogenesis, diagnosis, or treatment of OTB. We excluded abstracts and articles that were not written in the English language. References cited within the identified articles were used to further supplement the search. We found 10 studies evaluating the sensitivity and specificity of interferon-gamma release assay (IGRA), and 6 studies evaluating that of tuberculin skin test (TST) in OTB patients. IGRA (Sp = 71-100%, Se = 36-100%) achieves overall better sensitivity and specificity than TST (Sp = 51.1-85.7%; Se = 70.9-98.5%). For nuclear acid amplification tests (NAAT), we found 7 studies on uniplex polymerase chain reaction (PCR) with different Mtb targets, 7 studies on DNA-based multiplex PCR, 1 study on mRNA-based multiplex PCR, 4 studies on loop-mediated isothermal amplification (LAMP) assay with different Mtb targets, 3 studies on GeneXpert assay, 1 study on GeneXpert Ultra assay and 1 study for MTBDRplus assay for OTB. Specificity is overall improved but sensitivity is highly variable for NAATs (excluding uniplex PCR, Sp = 50-100%; Se = 10.5-98%) as compared to IGRA. We also found 3 transcriptomic studies, 6 proteomic studies, 2 studies on stimulation assays, 1 study on intraocular protein analysis and 1 study on T-lymphocyte profiling in OTB patients. All except 1 study evaluated novel, previously undiscovered biomarkers. Only 1 study has been externally validated by a large independent cohort. Future theranostic marker discovery by a multi-omics approach is essential to deepen pathophysiological understanding of OTB. Combined these might result in swift, optimal and personalized treatment regimens to modulate the heterogeneous mechanisms of OTB. Eventually, these studies could improve the current cumbersome diagnosis and management of OTB.

The Potential Importance of CXCL1 in the Physiological State and in Noncancer Diseases of the Cardiovascular System, Respiratory System and Skin

In this paper, we present a literature review of the role of CXC motif chemokine ligand 1 (CXCL1) in physiology, and in selected major non-cancer diseases of the cardiovascular system, respiratory system and skin. CXCL1, a cytokine belonging to the CXC sub-family of chemokines with CXC motif chemokine receptor 2 (CXCR2) as its main receptor, causes the migration and infiltration of neutrophils to the sites of high expression. This implicates CXCL1 in many adverse conditions associated with inflammation and the accumulation of neutrophils. The aim of this study was to describe the significance of CXCL1 in selected diseases of the cardiovascular system (atherosclerosis, atrial fibrillation, chronic ischemic heart disease, hypertension, sepsis including sepsis-associated encephalopathy and sepsis-associated acute kidney injury), the respiratory system (asthma, chronic obstructive pulmonary disease (COPD), chronic rhinosinusitis, coronavirus disease 2019 (COVID-19), influenza, lung transplantation and ischemic-reperfusion injury and tuberculosis) and the skin (wound healing, psoriasis, sunburn and xeroderma pigmentosum). Additionally, the significance of CXCL1 is described in vascular physiology, such as the effects of CXCL1 on angiogenesis and arteriogenesis.

A protein signature associated with active tuberculosis identified by plasma profiling and network-based analysis

Annually, approximately 10 million people are diagnosed with active tuberculosis (TB), and 1.4 million die of the disease. If left untreated, each person with active TB will infect 10-15 new individuals. The lack of non-sputum-based diagnostic tests leads to delayed diagnoses of active pulmonary TB cases, contributing to continued disease transmission. In this exploratory study, we aimed to identify biomarkers associated with active TB. We assessed the plasma levels of 92 proteins associated with inflammation in individuals with active TB (n = 20), latent TB (n = 14), or healthy controls (n = 10). Using co-expression network analysis, we identified one module of proteins with strong association with active TB. We removed proteins from the module that had low abundance or were associated with non-TB diseases in published transcriptomic datasets, resulting in a 12-protein plasma signature that was highly enriched in individuals with pulmonary and extrapulmonary TB and was further associated with disease severity.

Delamanid suppresses CXCL10 expression via regulation of JAK/STAT1 signaling and correlates with reduced inflammation in tuberculosis patients

Background

Apart from bactericidal effects, anti-tuberculosis drugs can interfere with the host’s immune system. In this study, we analyzed the role of delamanid (DLM), an inhibitor of mycolic acid synthesis of mycobacterial cell wall, on human macrophages.

Methods

Based on a cohort of multidrug-resistant tuberculosis (MDR-TB) patients treated with DLM, the levels of C-reaction protein (CRP) and cytokines in the plasma were monitored using immunoturbidimetric assay and flow cytometry, respectively. We investigated the role of DLM on CXCL10 expression in U937 cell model using the following methods: cell viability assay, reverse transcription-quantitative polymerase chain reaction, enzyme linked immunosorbent assay, immunoblot, and transwell co-culture assay.

Results

A total of 23 MDR-TB patients were included, comprising of 13 patients treated with optimized background therapeutic regimen (OBR) plus DLM regimen (OBR+DLM) and 10 patients treated with OBR plus placebo. DLM administration was associated with a significant reduce in circulating CRP level. Correspondingly, after treatment, the level of CXCL10 in patients treated with OBR+DLM was significantly lower than that with control. Using cell model, DLM dramatically suppressed CXCL10 expression, which majorly depended on inhibiting the JAK/STAT pathway, and impaired the migration of PBMCs.

Conclusion

Our data firstly demonstrate that DLM suppresses CXCL10 expression via regulation of JAK2/STAT1 signaling and correlates with reduced inflammation in MDR-TB patients. DLM could be used as a potential drug for immunotherapy of patients with overactive immune response due to CXCL10.

Resistance and Susceptibility Immune Factors at Play during Mycobacterium tuberculosis Infection of Macrophages

Tuberculosis (TB), caused by infection with Mycobacterium tuberculosis (M.tb), is responsible for >1.5 million deaths worldwide annually. Innate immune cells, especially macrophages, are the first to encounter M.tb, and their response dictates the course of infection. During infection, macrophages exert a variety of immune factors involved in either controlling or promoting the growth of M.tb. Research on this topic has been performed in both in vitro and in vivo animal models with discrepant results in some cases based on the model of study. Herein, we review macrophage resistance and susceptibility immune factors, focusing primarily on recent advances in the field. We include macrophage cellular pathways, bioeffector proteins and molecules, cytokines and chemokines, associated microbiological factors and bacterial strains, and host genetic factors in innate immune genes. Recent advances in mechanisms underlying macrophage resistance and susceptibility factors will aid in the successful development of host-directed therapeutics, a topic emphasized throughout this review.

Comparison of interferon gamma release assay and CXCL9 gene expression assay for the detection of Mycobacterium bovis infection in African lions (Panthera leo)

Mycobacterium bovis (M. bovis) infection has been identified in both domestic and wild animals and may threaten the conservation of vulnerable species including African lions (Panthera leo). There is a need to develop accurate ante-mortem tools for detection of M. bovis infection in African big cat populations for wildlife management and disease surveillance. The aim of this study was to compare the performances of two immunological assays, the QuantiFERON®-TB Gold Plus (QFT) Mabtech Cat interferon gamma release assay (IGRA) and QFT CXCL9 gene expression assay (GEA), which have both shown diagnostic potential for M. bovis detection in African lions. Lion whole blood (n=47), stimulated using the QFT platform, was used for measuring antigen-specific CXCL9 expression and IFN-γ production and to assign M. bovis infection status. A subset (n=12) of mycobacterial culture-confirmed M. bovis infected and uninfected African lions was used to compare the agreement between the immunological diagnostic assays. There was no statistical difference between the proportions of test positive African lions tested by the QFT Mabtech Cat IGRA compared to the QFT CXCL9 GEA. There was also a moderate association between immunological diagnostic assays when numerical results were compared. The majority of lions had the same diagnostic outcome using the paired assays. Although the QFT Mabtech Cat IGRA provides a more standardized, commercially available, and cost-effective test compared to QFT CXCL9 GEA, using both assays to categorize M. bovis infection status in lions will increase confidence in results.

Plasma biomarkers for systemic inflammation in COVID-19 survivors

BACKGROUND

While the majority of COVID-19 patients fully recover from the infection and become asymptomatic, a significant proportion of COVID-19 survivors experience a broad spectrum of symptoms lasting weeks to months post-infection, a phenomenon termed "post-acute sequelae of COVID-19 (PASC)." The aim of this study is to determine whether inflammatory proteins are dysregulated and can serve as potential biomarkers for systemic inflammation in COVID-19 survivors.

METHODS

We determined the levels of inflammatory proteins in plasma from 22 coronavirus disease 2019 (COVID-19) long haulers (COV-LH), 22 COVID-19 asymptomatic survivors (COV-AS), and 22 healthy subjects (HS) using an Olink proteomics assay and assessed the results by a beads-based multiplex immunoassay.

RESULTS

Compared to HS, we found that COVID-19 survivors still exhibited systemic inflammation, as evidenced by significant changes in the levels of multiple inflammatory proteins in plasma from both COV-LH and COV-AS. CXCL10 was the only protein that significantly upregulated in COV-LH compared with COV-AS and HS.

CONCLUSIONS

Our results indicate that several inflammatory proteins remain aberrantly dysregulated in COVID-19 survivors and CXCL10 might serve as a potential biomarker to typify COV-LH. Further characterization of these signature inflammatory molecules might improve the understanding of the long-term impacts of COVID-19 and provide new targets for the diagnosis and treatment of COVID-19 survivors with PASC.

Comprehensive lipid and lipid-related gene investigations of host immune responses to characterize metabolism-centric biomarkers for pulmonary tuberculosis

Despite remarkable success in the prevention and treatment of tuberculosis (TB), it remains one of the most devastating infectious diseases worldwide. Management of TB requires an efficient and timely diagnostic strategy. In this study, we comprehensively characterized the plasma lipidome of TB patients, then selected candidate lipid and lipid-related gene biomarkers using a data-driven, knowledge-based framework. Among 93 lipids that were identified as potential biomarker candidates, ether-linked phosphatidylcholine (PC O–) and phosphatidylcholine (PC) were generally upregulated, while free fatty acids and triglycerides with longer fatty acyl chains were downregulated in the TB group. Lipid-related gene enrichment analysis revealed significantly altered metabolic pathways (e.g., ether lipid, linolenic acid, and cholesterol) and immune response signaling pathways. Based on these potential biomarkers, TB patients could be differentiated from controls in the internal validation (random forest model, area under the curve [AUC] 0.936, 95% confidence interval [CI] 0.865–0.992). PC(O-40:4), PC(O-42:5), PC(36:0), and PC(34:4) were robust biomarkers able to distinguish TB patients from individuals with latent infection and healthy controls, as shown in the external validation. Small changes in expression were identified for 162 significant lipid-related genes in the comparison of TB patients vs. controls; in the random forest model, their utilities were demonstrated by AUCs that ranged from 0.829 to 0.956 in three cohorts. In conclusion, this study introduced a potential framework that can be used to identify and validate metabolism-centric biomarkers.

Exploring key molecular signatures of immune responses and pathways associated with tuberculosis in comorbid diabetes mellitus: a systems biology approach

Background

Comorbid type 2 diabetes mellitus (T2DM) increases the risk for tuberculosis (TB) and its associated complications, although the pathological connections between T2DM and TB are unknown. The current research aims to identify shared molecular gene signatures and pathways that affirm the epidemiological association of T2DM and TB and afford clues on mechanistic basis of their association through integrative systems biology and bioinformatics approaches. Earlier research has found specific molecular markers linked to T2DM and TB, but, despite their importance, only offered a limited understanding of the genesis of this comorbidity. Our investigation used a network medicine method to find possible T2DM-TB molecular mediators.

Results

Functional annotation clustering, interaction networks, network cluster analysis, and network topology were part of our systematic investigation of T2DM-TB linked with 1603 differentially expressed genes (DEGs). The functional enrichment and gene interaction network analysis emphasized the importance of cytokine/chemokine signalling, T cell receptor signalling route, NF-kappa B signalling pathway and Jak-STAT signalling system. Furthermore, network analysis revealed significant DEGs such as ITGAM and STAT1, which may be necessary for T2DM-TB immune responses. Furthermore, these two genes are modulators in clusters C4 and C5, abundant in cytokine/chemokine signalling and Jak-STAT signalling pathways.

Conclusions

Our analyses highlight the role of ITGAM and STAT1 in T2DM-TB-associated pathways and advances our knowledge of the genetic processes driving this comorbidity.

A Dual Role of Heme Oxygenase-1 in Tuberculosis

Iron metabolism is vital for the survival of both humans and microorganisms. Heme oxygenase-1 (HO-1) is an essential stress-response enzyme highly expressed in the lungs, and catabolizes heme into ferrous iron, carbon monoxide (CO), and biliverdin (BV)/bilirubin (BR), especially in pathological conditions which cause oxidative stress and inflammation. Ferrous iron (Fe²⁺) is an important raw material for the synthesis of hemoglobin in red blood cells, and patients with iron deficiency are often associated with decreased cellular immunity. CO and BR can inhibit oxidative stress and inflammation. Thus, HO-1 is regarded as a cytoprotective molecule during the infection process. However, recent study has unveiled new information regarding HO-1. Being a highly infectious pathogenic bacterium, Mycobacterium tuberculosis (MTB) infection causes acute oxidative stress, and increases the expression of HO-1, which may in turn facilitate MTB survival and growth due to increased iron availability. Moreover, in severe cases of MTB infection, excessive reactive oxygen species (ROS) and free iron (Fe²⁺) due to high levels of HO-1 can lead to lipid peroxidation and ferroptosis, which may promote further MTB dissemination from cells undergoing ferroptosis. Therefore, it is important to understand and illustrate the dual role of HO-1 in tuberculosis. Herein, we critically review the interplay among HO-1, tuberculosis, and the host, thus paving the way for development of potential strategies for modulating HO-1 and iron metabolism.

Plasma Chemokines Are Baseline Predictors of Unfavorable Treatment Outcomes in Pulmonary Tuberculosis

BACKGROUND

Plasma chemokines are biomarkers of greater disease severity, higher bacterial burden, and delayed sputum culture conversion in pulmonary tuberculosis (PTB). Whether plasma chemokines could also serve as biomarkers of unfavorable treatment outcomes in PTB is not known.

METHODS

A cohort of newly diagnosed, sputum smear- and culture-positive adults with drug-sensitive PTB were recruited under the Effect of Diabetes on Tuberculosis Severity study in Chennai, India. Plasma chemokine levels measured before treatment initiation were compared between 68 cases with unfavorable outcomes (treatment failure, death, or recurrence) and 136 control individuals who had recurrence-free cure. A second validation cohort comprising newly diagnosed, culture-positive adults with drug-sensitive TB was used to measure plasma chemokine levels in 20 cases and 40 controls.

RESULTS

Six chemokines (CCL2, CCL3, CCL4, CXCL8, CXCL10, and CX3CL1) were associated with increased risk, while CXCL1 was associated with decreased risk of unfavorable outcomes in unadjusted and adjusted analyses in the test cohort. Similarly, CCL3, CXCL8, and CXCL10 were associated with increased risk of unfavorable treatment outcomes in the validation cohort. Receiver operating characteristic analysis revealed that combinations of CCL3, CXCL8, and CXCL10 exhibited very high sensitivity and specificity in differentiating cases vs controls.

CONCLUSIONS

Our study reveals a plasma chemokine signature that can be used as a novel biomarker for predicting adverse treatment outcomes in PTB.

C-X-C Chemokines Influence Intraocular Inflammation During Bacillus Endophthalmitis

Purpose

The purpose of this study was to explore the C-X-C chemokines CXCL2 and CXCL10 as potential anti-inflammatory targets for Bacillus endophthalmitis.

Methods

Bacillus endophthalmitis was induced in C57BL/6J, CXCL2^−/−, and CXCL10^−/− mice. At specific times postinfection, eyes were analyzed for Bacillus, retinal function, and inflammation. The efficacies of intravitreal anti-CXCL2 and anti-CXCL10 with or without gatifloxacin in B. cereus endophthalmitis were also assessed using the same techniques.

Results

Despite similar Bacillus growth in eyes of C57BL/6J, CXCL2^−/−, and CXCL10^−/− mice, retinal function retention was greater in eyes of CXCL2^−/− and CXCL10^−/− mice compared to that of C57BL/6J mice. Neutrophil migration into eyes of CXCL2^−/− and CXCL10^−/− mice was reduced to a greater degree compared to that of eyes of C57BL/6J mice. Infected CXCL2^−/− and CXCL10^−/− mouse eyes had significantly less inflammation compared to that of C57BL/6J eyes. Retinal structures in infected eyes of CXCL2^−/− mice were preserved for a longer time than in CXCL10^−/− eyes. Compared to untreated eyes, there was less inflammation and significant retention of retinal function in eyes treated with anti-CXCL2 and anti-CXCL10 with or without gatifloxacin.

Conclusions

For Bacillus endophthalmitis, the absence of CXCL2 or CXCL10 in mice resulted in retained retinal function and less inflammation. The absence of CXCL2 led to a better clinical outcome than the absence of CXCL10. The use of anti-CXCL2 and anti-CXCL10 limited inflammation during B. cereus endophthalmitis. These results highlight the utility of CXCL2 and CXCL10 as potential targets for anti-inflammatory therapy that can be tested in conjunction with antibiotics for improving treating Bacillus endophthalmitis.

Plasma chemokines as immune biomarkers for diagnosis of pediatric tuberculosis

Background

Diagnosing tuberculosis (TB) in children is challenging due to paucibacillary disease, and lack of ability for microbiologic confirmation. Hence, we measured the plasma chemokines as biomarkers for diagnosis of pediatric tuberculosis.

Methods

We conducted a prospective case control study using children with confirmed, unconfirmed and unlikely TB. Multiplex assay was performed to examine the plasma CC and CXC levels of chemokines.

Results

Baseline levels of CCL1, CCL3, CXCL1, CXCL2 and CXCL10 were significantly higher in active TB (confirmed TB and unconfirmed TB) in comparison to unlikely TB children. Receiver operating characteristics curve analysis revealed that CCL1, CXCL1 and CXCL10 could act as biomarkers distinguishing confirmed or unconfirmed TB from unlikely TB with the sensitivity and specificity of more than 80%. In addition, combiROC exhibited more than 90% sensitivity and specificity in distinguishing confirmed and unconfirmed TB from unlikely TB. Finally, classification and regression tree models also offered more than 90% sensitivity and specificity for CCL1 with a cutoff value of 28 pg/ml, which clearly classify active TB from unlikely TB. The levels of CCL1, CXCL1, CXCL2 and CXCL10 exhibited a significant reduction following anti-TB treatment.

Conclusion

Thus, a baseline chemokine signature of CCL1/CXCL1/CXCL10 could serve as an accurate biomarker for the diagnosis of pediatric tuberculosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06749-6.

Adjunct n-3 Long-Chain Polyunsaturated Fatty Acid Treatment in Tuberculosis Reduces Inflammation and Improves Anemia of Infection More in C3HeB/FeJ Mice With Low n-3 Fatty Acid Status Than Sufficient n-3 Fatty Acid Status

Populations at risk for tuberculosis (TB) may have a low n-3 polyunsaturated fatty acid (PUFA) status. Our research previously showed that post-infection supplementation of n-3 long-chain PUFA (LCPUFA) in TB without TB medication was beneficial in n-3 PUFA sufficient but not in low-status C3HeB/FeJ mice. In this study, we investigated the effect of n-3 LCPUFA adjunct to TB medication in TB mice with a low compared to a sufficient n-3 PUFA status. Mice were conditioned on an n-3 PUFA-deficient (n-3FAD) or n-3 PUFA-sufficient (n-3FAS) diet for 6 weeks before TB infection. Post-infection at 2 weeks, both groups were switched to an n-3 LCPUFA [eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA)] supplemented diet and euthanized at 4- and 14- days post-treatment. Iron and anemia status, bacterial loads, lung pathology, lung cytokines/chemokines, and lung lipid mediators were measured. Following 14 days of treatment, hemoglobin (Hb) was higher in the n-3FAD than the untreated n-3FAS group (p = 0.022), whereas the n-3FAS (drug) treated control and n-3FAS groups were not. Pro-inflammatory lung cytokines; interleukin-6 (IL-6) (p = 0.011), IL-1α (p = 0.039), MCP1 (p = 0.003), MIP1- α (p = 0.043), and RANTES (p = 0.034); were lower, and the anti-inflammatory cytokine IL-4 (p = 0.002) and growth factor GMCSF (p = 0.007) were higher in the n-3FAD compared with the n-3FAS mice after 14 days. These results suggest that n-3 LCPUFA therapy in TB-infected mice, in combination with TB medication, may improve anemia of infection more in low n-3 fatty acid status than sufficient status mice. Furthermore, the low n-3 fatty acid status TB mice supplemented with n-3 LCPUFA showed comparatively lower cytokine-mediated inflammation despite presenting with lower pro-resolving lipid mediators.

CXCL1: A new diagnostic biomarker for human tuberculosis discovered using Diversity Outbred mice

More humans have died of tuberculosis (TB) than any other infectious disease and millions still die each year. Experts advocate for blood-based, serum protein biomarkers to help diagnose TB, which afflicts millions of people in high-burden countries. However, the protein biomarker pipeline is small. Here, we used the Diversity Outbred (DO) mouse population to address this gap, identifying five protein biomarker candidates. One protein biomarker, serum CXCL1, met the World Health Organization’s Targeted Product Profile for a triage test to diagnose active TB from latent M.tb infection (LTBI), non-TB lung disease, and normal sera in HIV-negative, adults from South Africa and Vietnam. To find the biomarker candidates, we quantified seven immune cytokines and four inflammatory proteins corresponding to highly expressed genes unique to progressor DO mice. Next, we applied statistical and machine learning methods to the data, i.e., 11 proteins in lungs from 453 infected and 29 non-infected mice. After searching all combinations of five algorithms and 239 protein subsets, validating, and testing the findings on independent data, two combinations accurately diagnosed progressor DO mice: Logistic Regression using MMP8; and Gradient Tree Boosting using a panel of 4: CXCL1, CXCL2, TNF, IL-10. Of those five protein biomarker candidates, two (MMP8 and CXCL1) were crucial for classifying DO mice; were above the limit of detection in most human serum samples; and had not been widely assessed for diagnostic performance in humans before. In patient sera, CXCL1 exceeded the triage diagnostic test criteria (>90% sensitivity; >70% specificity), while MMP8 did not. Using Area Under the Curve analyses, CXCL1 averaged 94.5% sensitivity and 88.8% specificity for active pulmonary TB (ATB) vs LTBI; 90.9% sensitivity and 71.4% specificity for ATB vs non-TB; and 100.0% sensitivity and 98.4% specificity for ATB vs normal sera. Our findings overall show that the DO mouse population can discover diagnostic-quality, serum protein biomarkers of human TB.

More humans die of tuberculosis (TB) than any other infectious disease, yet diagnostic tools remain limited. Here, we used the Diversity Outbred mouse population to discover candidate protein biomarkers of human TB. By applying statistical methods and machine learning to multidimensional data, we identified CXCL1 and MMP8 as the two most promising protein biomarker candidates. When evaluated in samples from human patients, CXCL1 achieved the World Health Organization’s targeted profile for a triage diagnostic test, discriminating active TB from important clinical differential diagnoses: latent Mtb infection and non-TB lung disease in HIV-negative adults. Overall, our studies show how a translationally relevant animal population model can accelerate TB biomarker discovery, validation, and testing for humans.

Plasma LOX-Products and Monocyte Signaling Is Reduced by Adjunctive Cyclooxygenase-2 Inhibitor in a Phase I Clinical Trial of Tuberculosis Patients

Introduction

Eicosanoids and intracellular signaling pathways are potential targets for host-directed therapy (HDT) in tuberculosis (TB). We have explored the effect of cyclooxygenase 2 inhibitor (COX-2i) treatment on eicosanoid levels and signaling pathways in monocytes.

Methods

Peripheral blood mononuclear cells isolated from TB patients included in a randomized phase I clinical trial of standard TB treatment with (n=21) or without (n=18) adjunctive COX-2i (etoricoxib) were analyzed at baseline, day 14 and day 56. Plasma eicosanoids were analyzed by ELISA and liquid chromatography-mass spectrometry (LC-MS), plasma cytokines by multiplex, and monocyte signaling by phospho-flow with a defined set of phospho-specific antibodies.

Results

Lipoxygenase (LOX)-derived products (LXA4 and 12-HETE) and pro-inflammatory cytokines were associated with TB disease severity and were reduced during TB therapy, possibly accelerated by adjunctive COX-2i. Phosphorylation of p38 MAPK, NFkB, Erk1/2, and Akt in monocytes as well as plasma levels of MIG/CXCL9 and procalcitonin were reduced in the COX-2i group compared to controls.

Conclusion

COX-2i may reduce excess inflammation in TB via the LOX-pathway in addition to modulation of phosphorylation patterns in monocytes. Immunomodulatory effects of adjunctive COX-2i in TB should be further investigated before recommended for use as a HDT strategy.

Perspectives for systems biology in the management of tuberculosis

Standardised management of tuberculosis may soon be replaced by individualised, precision medicine-guided therapies informed with knowledge provided by the field of systems biology. Systems biology is a rapidly expanding field of computational and mathematical analysis and modelling of complex biological systems that can provide insights into mechanisms underlying tuberculosis, identify novel biomarkers, and help to optimise prevention, diagnosis and treatment of disease. These advances are critically important in the context of the evolving epidemic of drug-resistant tuberculosis. Here, we review the available evidence on the role of systems biology approaches - human and mycobacterial genomics and transcriptomics, proteomics, lipidomics/metabolomics, immunophenotyping, systems pharmacology and gut microbiomes - in the management of tuberculosis including prediction of risk for disease progression, severity of mycobacterial virulence and drug resistance, adverse events, comorbidities, response to therapy and treatment outcomes. Application of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach demonstrated that at present most of the studies provide "very low" certainty of evidence for answering clinically relevant questions. Further studies in large prospective cohorts of patients, including randomised clinical trials, are necessary to assess the applicability of the findings in tuberculosis prevention and more efficient clinical management of patients.

Effect of Inflammatory Cytokines/Chemokines on Pulmonary Tuberculosis Culture Conversion and Disease Severity in HIV-Infected and -Uninfected Individuals From South Africa

Novel tuberculosis (TB) prevention and control strategies are urgently required. Utilising specimens from the Improving Retreatment Success (NCT02114684) trial we assessed the associations between inflammatory markers, measured during active TB, with treatment response and disease severity in HIV-infected and uninfected individuals. Multiplex immunoassays and ELISA were used to measure plasma expression of 24 cytokines/chemokines. Cytokines were log transformed to adjust for skewness. We conducted a nested, un-matched, case (n= 31) - control (n=101) study with cases defined as those participants who failed to sputum culture convert within 8-weeks of TB treatment initiation. Additionally, we examined the association between the measured cytokines and time to culture conversion and presence of lung cavitation using cox proportional hazards and logistic regression models, respectively. Multivariable analyses adjusted for a wide range of baseline clinical and demographic variables. IP-10 expression during active TB was associated with increased odds of sputum culture conversion by 8-weeks overall (aOR 4.255, 95% CI 1.025 – 17.544, p=0.046)) and among HIV-infected individuals (OR 10.204, 95% CI 1.247 – 83.333, p=0.030). Increased MCP-3 (aHR 1.723, 95% CI 1.040 – 2.855, p=0.035) and IL-6 (aHR 1.409, 95% CI 1.045 – 1.899, p=0.024) expression was associated with a shorter time to culture conversion in the total cohort. Higher plasma expression of IL-6 (aHR 1.783, 95% CI 1.128 – 2.820, p=0.013), IL-1RA (aHR 2.595, 95% CI 1.136 – 5.926, p=0.024), IP-10 (aHR 2.068, 95% CI 1.034 – 4.137, p=0.040) and IL-1α (aHR 2.008, 95% CI 1.053 – 3.831, p=0.035) were significantly associated with shorter time to culture conversion among HIV-infected individuals. Increased IL-6 and IL-1RA expression was significantly associated with the presence of lung cavitation during active TB in the total cohort (OR 2.543, 95% CI 1.254 – 5.160, p=0.010), (OR 4.639, 95% CI 1.203 – 21.031, p=0.047) and in HIV-infected individuals (OR 2.644, 95% CI 1.062 – 6.585, p=0.037), (OR 7.795, 95% CI 1.177 – 51.611, p=0.033) respectively. Our results indicate that inflammatory cytokines/chemokines play an important role in TB disease outcome. Importantly, the observed associations were stronger in multivariable models highlighting the impact of behavioural and clinical variables on the expression of immune markers as well as their potential effects on TB outcome.

Potential diagnostic value of pleural fluid cytokines levels for tuberculous pleural effusion

Patients with tuberculous pleural effusion (TPE) or malignant pleural effusions (MPE) frequently have similar pleural fluid profiles. New biomarkers for the differential diagnosis of TPE are required. We determined whether cytokine profiles in the PE of patients could aid the differential diagnosis of TPE. 30 patients with TPE, 30 patients with MPE, 14 patients with empyema (EMP) and 14 patients with parapneumonic effusion (PPE) were enrolled between Dec 2018 and 2019. The levels of interleukin (IL)-6, IL-18, IL-27, CXCL8, CCL-1 and IP-10 were determined in PE by ELISA along with measurements of adenosine deaminase (ADA). The best predictors of TPE were combined ADA.IL-27 [optimal cut-off value = 42.68 (10³ U ng/l²), sensitivity 100%, specificity 98.28%], ADA [cut off value 27.5 (IU/l), sensitivity 90%, specificity 96.5%] and IL-27 [cut-off value = 2363 (pg/ml), sensitivity 96.7%, specificity 98.3%, p ≤ 0.0001]. A high level of IL-6 [cut-off value = 3260 (pg/ml), sensitivity 100%, specificity 67.2%], CXCL8 [cut-off value = 144.5 (pg/ml), sensitivity 93.3%, specificity 58.6%], CCL1 [cut-off value = 54 (pg/ml), sensitivity 100%, specificity 70.7%] and IP-10 [cut-off value = 891.9 (pg/ml), sensitivity 83.3%, specificity 48.3%] were also predictive of TPE. High ADA.IL-27, ADA and IL-27 levels differentiate between TPE and non-TPE with improved specificity and diagnostic accuracy and may be useful clinically.

Major Neutrophil-Derived Soluble Mediators Associate With Baseline Lung Pathology and Post-Treatment Recovery in Tuberculosis Patients

Background

The inflammatory response to Mycobacterium tuberculosis results in variable degrees of lung pathology during active TB (ATB) with central involvement of neutrophils. Little is known about neutrophil-derived mediators and their role in disease severity at baseline and recovery upon TB treatment initiation.

Methods

107 adults with confirmed pulmonary TB were categorised based on lung pathology at baseline and following successful therapy using chest X-ray scores (Ralph scores) and GeneXpert bacterial load (Ct values). Plasma, sputum, and antigen-stimulated levels of MMP1, MMP3, MMP8, MMP9, MPO, S100A8/9, IL8, IL10, IL12/23(p40), GM-CSF, IFNγ, and TNF were analysed using multiplex cytokine arrays.

Results

At baseline, neutrophil counts correlated with plasma levels of MMP8 (rho = 0.45, p = 2.80E-06), S100A8 (rho = 0.52, p = 3.00E-08) and GM-CSF (rho = 0.43, p = 7.90E-06). Levels of MMP8 (p = 3.00E-03), MMP1 (p = 1.40E-02), S100A8 (p = 1.80E-02) and IL12/23(p40) (p = 1.00E-02) were associated with severe lung damage, while sputum MPO levels were directly linked to lung damage (p = 1.80E-03), Mtb load (p = 2.10E-02) and lung recovery (p = 2.40E-02). Six months of TB therapy significantly decreased levels of major neutrophil-derived pro-inflammatory mediators: MMP1 (p = 4.90E-12 and p = 2.20E-07), MMP8 (p = 3.40E-14 and p = 1.30E-05) and MMP9 (p = 1.60E-04 and p = 1.50E-03) in plasma and sputum, respectively. Interestingly, following H37Rv whole cell lysate stimulation, S100A8 (p = 2.80E-02), MMP9 (p = 3.60E-02) and MPO (p = 9.10E-03) levels at month 6 were significantly higher compared to baseline. Sputum MMP1 (p = 1.50E-03), MMP3 (p = 7.58E-04), MMP9 (p = 2.60E-02) and TNF (p = 3.80E-02) levels were lower at month 6 compared to baseline in patients with good lung recovery.

Conclusion

In this study, patients with severe lung pathology at baseline and persistent lung damage after treatment were associated with higher plasma and sputum levels of major pro-inflammatory neutrophil-derived mediators. Interestingly, low sputum MPO levels were associated with severe lung damage, higher Mtb burden and low recovery. Our data suggest that therapeutic agents which target these mediators should be considered for future studies on biomarkers and host-directed therapeutic approaches against TB-related lung pathology and/or lung recovery.

Filarial Coinfection Is Associated With Higher Bacterial Burdens and Altered Plasma Cytokine and Chemokine Responses in Tuberculous Lymphadenitis

Filarial infections are known to modulate cytokine responses in pulmonary tuberculosis by their propensity to induce Type 2 and regulatory cytokines. However, very little is known about the effect of filarial infections on extra-pulmonary forms of tuberculosis. Thus, we have examined the effect of filarial infections on the plasma levels of various families of (IL-1, IL-12, γC, and regulatory) cytokines and (CC and CXC) chemokines in tuberculous lymphadenitis coinfection. We also measured lymph node culture grades in order to assess the burden of Mycobacterium tuberculosis in the two study groups [Fil+ (n = 67) and Fil– (n = 109)]. Our data reveal that bacterial burden was significantly higher in Fil+ compared to Fil– individuals. Plasma levels of IL-1 family (IL-1α, IL-β, IL-18) cytokines were significantly lower with the exception of IL-33 in Fil+ compared to Fil– individuals. Similarly, plasma levels of IL-12 family cytokines -IL-12 and IL-23 were significantly reduced, while IL-35 was significantly elevated in Fil+ compared to Fil– individuals. Filarial infection was also associated with diminished levels of IL-2, IL-9 and enhanced levels of IL-4, IL-10, and IL-1Ra. Similarly, the Fil+ individuals were linked to elevated levels of different CC (CCL-1, CCL-2, CCL-3, CCL-11) and CXC (CXCL-2, CXCL-8, CXCL-9, CXCL-11) chemokines. Therefore, we conclude that filarial infections exert powerful bystander effects on tuberculous lymphadenitis, effects including modulation of protective cytokines and chemokines with a direct impact on bacterial burdens.