Gender biased immune-biomarkers in active tuberculosis and correlation of their profiles to efficacy of therapy

New Insights into Biomarkers for Evaluating Therapy Efficacy in Pulmonary Tuberculosis: A Narrative Review

Evaluating therapy efficacy is crucial for patients with tuberculosis (TB), especially those with drug-resistant tuberculosis (DR-TB). The World Health Organization currently recommends sputum smear and culture as the standard methods for evaluating pulmonary tuberculosis (PTB) therapy efficacy. However, these approaches have limitations including low sensitivity, lengthy culture periods, and susceptibility to contamination. There is an urgent need for dependable biomarkers to evaluate therapy efficacy in patients with PTB. Numerous new biomarkers of Mycobacterium tuberculosis (MTB) and the host have been used in recent studies to evaluate PTB therapy efficacy. A systematic review and update of these biomarkers can facilitate the discovery of novel biomarkers and assessment models, as well as provide a solid scientific basis for alternative indicators of evaluating therapy efficacy. In this review we summarize the recent advancements and limitations of biomarkers used to monitor therapy efficacy, highlighting the importance of utilizing a combination of biomarkers. Although some biomarkers have potential in evaluating the efficacy of therapy in patients with PTB, they also have some limitations. Further research, validation, and optimization are required to identify the most reliable and effective alternative biomarkers and apply them to clinical practice.

Lipid Mediators and Cytokines/Chemokines Display Differential Profiles in Severe versus Mild/Moderate COVID-19 Patients

Host immune responses play a key role in COVID-19 pathogenesis. The underlying phenomena are orchestrated by signaling molecules such as cytokines/chemokines and lipid mediators. These immune molecules, including anti-SARS-CoV-2 antibodies, interact with immune cells and regulate host responses, contributing to inflammation that drives the disease. We investigated 48 plasma cytokines/chemokines, 21 lipid mediators, and anti-S protein (RBD) antibodies in COVID-19 patients (n = 56) and non-COVID-19 respiratory disease controls (n = 49), to identify immune-biomarker profiles. Cytokines/chemokines (IL-6, CXCL-10 (IP-10), HGF, MIG, MCP-1, and G-CSF) and lipid mediators (TxB2, 11-HETE, 9-HODE, 13-HODE, 5-HETE, 12-HETE, 15-HETE, 14S-HDHA, 17S-HDHA, and 5-oxo ETE) were significantly elevated in COVID-19 patients compared to controls. In patients exhibiting severe disease, pro-inflammatory cytokines/chemokines (IL-6, CXCL-10, and HGF) and anti-SARS-CoV-2 antibodies were significantly elevated. In contrast, lipid mediators involved in the reduction/resolution of inflammation, in particular, 5-HETE, 11-HETE, and 5-oxoETE, were significantly elevated in mild/moderate disease. Taken together, these immune-biomarker profiles provide insight into immune responses related to COVID-19 pathogenesis. Importantly, our findings suggest that elevation in plasma concentrations of IL-6, CXCL-10, HGF, and anti-SARS-CoV-2 antibodies can predict severe disease, whereas elevation in lipid mediators peaks early (compared to cytokines) and includes induction of mechanisms leading to reduction of inflammation, associated complications, and maintenance of homeostasis.

Vitamin D and estrogen steroid hormones and their immunogenetic roles in Infectious respiratory (TB and COVID-19) diseases

The role of steroid hormones against infectious diseases has been extensively studied. From immunomodulatory action to direct inhibition of microorganism growth, hormones D3 (VD3) and 17β-estradiol (E2), and the genetic pathways modulated by them, are key targets for a better understanding pathogenesis of infectious respiratory diseases (IRD) such as tuberculosis (TB) and the coronavirus disease-19 (COVID-19). Currently, the world faces two major public health problems, the outbreak of COVID-19, accounting for more than 6 million so far, and TB, more than 1 million deaths per year. Both, although resulting from different pathogens, the Mtb and the SARS-CoV-2, respectively, are considered serious and epidemic. TB and COVID-19 present similar infection rates between men and women, however the number of complications and deaths resulting from the two infections is higher in men when compared to women in childbearing age, which may indicate a role of the sex hormone E2 in the context of these diseases. E2 and VD3 act upon key gene pathways as important immunomodulatory players and supporting molecules in IRDs. This review summarizes the main roles of these hormones (VD3 and E2) in modulating immune and inflammatory responses and their relationship with TB and COVID-19.

Immune response dynamics in COVID-19 patients to SARS-CoV-2 and other human coronaviruses

COVID-19 serological test must have high sensitivity as well as specificity to rule out cross-reactivity with common coronaviruses (HCoVs). We have developed a quantitative multiplex test, measuring antibodies against spike (S) proteins of SARS-CoV-2, SARS-CoV, MERS-CoV, and common human coronavirus strains (229E, NL63, OC43, HKU1), and nucleocapsid (N) protein of SARS-CoV viruses. Receptor binding domain of S protein of SARS-CoV-2 (S-RBD), and N protein, demonstrated sensitivity (94% and 92.5%, respectively) in COVID-19 patients (n = 53), with 98% specificity in non-COVID-19 respiratory-disease (n = 98), and healthy-controls (n = 129). Anti S-RBD and N antibodies appeared five to ten days post-onset of symptoms, peaking at approximately four weeks. The appearance of IgG and IgM coincided while IgG subtypes, IgG1 and IgG3 appeared soon after the total IgG; IgG2 and IgG4 remained undetectable. Several inflammatory cytokines/chemokines were found to be elevated in many COVID-19 patients (e.g., Eotaxin, Gro-α, CXCL-10 (IP-10), RANTES (CCL5), IL-2Rα, MCP-1, and SCGF-b); CXCL-10 was elevated in all. In contrast to antibody titers, levels of CXCL-10 decreased with the improvement in patient health suggesting it as a candidate for disease resolution. Importantly, anti-N antibodies appear before S-RBD and differentiate between vaccinated and infected people-current vaccines (and several in the pipeline) are S protein-based.

Significance of the chemokine CXCL10 and human beta-defensin-3 as biomarkers of pulmonary tuberculosis

The biomarker significance of IL-35, chemokines (CXCL9 and CXCL10) and human beta-defensins (hBD2 and hBD3) was determined in pulmonary tuberculosis (TB) of 105 Iraqi patients; 37 had active disease, 41 had multi-drug resistant (MDR) PTB and 27 had a relapse of TB. A control sample of 79 healthy persons was also included. Serum levels of markers were assessed using enzyme-linked immunosorbent assay kits. Kruskal-Wallis test together with Dunn-Bonferroni post hoc test revealed significance differences between patients and controls in levels of IL-35, CXCL9, CXCL10 and hBD3, while hBD2 showed no significant difference. Receiver operating characteristic analysis demonstrated that CXCL10 and hBD3 were the most significant markers in predicting TB, particularly active disease. Logistic regression analysis proposed the susceptibility role of CXCL10 in TB. Gender- and age-dependent variations were also observed. Spearman's rank correlation analysis showed different correlations between markers in each group of patients and controls. In conclusion, CXCL10 was up-regulated in serum of TB patients, while hBD3 showed down-regulated level. Both serum proteins are possible candidate biomarkers for evaluation of TB progression, particularly in active disease.

Male Sex Bias in Immune Biomarkers for Tuberculosis

Males have a bias toward developing sputum smear-positive pulmonary tuberculosis, whereas other forms of the disease have an equal sex ratio. Immune responses are known to be affected by estrogen and testosterone. Biomarkers may therefore be affected by these hormones, especially between 16 and 45 years of age when the differences are most marked. Using large data sets, we examined whether the male bias was significant in terms of diagnosis or predictive ability for the development of disease in those exposed to tuberculosis. Despite the large numbers, the need to specify homogeneous population groups for analysis affected the statistical power to discount a useful biomarker. In general, males showed higher interferon-gamma responses to TB antigens ESAT-6 and CFP-10, whilst females had stronger tuberculin responses in those with sputum smear- and culture-positive tuberculosis, but smaller responses in those who were screened for tuberculosis and who did not develop disease. Importantly, in contacts of sputum smear-positive pulmonary tuberculosis, more males who did not develop tuberculosis had tuberculin skin tests in the range between 10 and 14 mm, suggesting that sex-specific cut-offs might be better than general cut-off values for determining who should receive preventive treatment. Immunocytochemistry of the tuberculin responses correlated with cell numbers only in females. Total and anti-lipoarabinomannan IgM antibody levels were lower in males, whereas total and anti-BCG IgE antibody levels were higher. Evaluation of biomarkers should take account of the spectrum of tuberculosis and male sex bias for sputum smear-positive pulmonary tuberculosis. These findings improve our understanding of how immune responses contribute to the pathogenesis of infectious tuberculosis as well as suggesting clinical applications of the differences between the sexes.

Enhanced serodiagnostic potential of a fusion molecule consisting of Rv1793, Rv2628 and a truncated Rv2608 of Mycobacterium tuberculosis

Serodiagnosis of tuberculosis (TB) can be rapid, reliable and cost-effective if the issue of variable antibody responses of TB patients against different Mycobacterium tuberculosis (Mtb) antigens can be overcome by developing fusion proteins containing epitopes from multiple antigens of Mtb. In this study, Mtb antigens Rv1793, Rv2628, Rv2608 and a truncated variant produced by removing non-epitopic region from N-terminal of Rv2608 (tnRv2608), and the fusion protein Rv1793-Rv2628-tnRv2608 (TriFu64), were expressed in E. coli and purified. Plasma samples from TB patients characterized by sex, age and sputum/culture positivity, were used to compare the sensitivity of the single antigens with the fusion protein. Sensitivity of Rv1793, Rv2628 and Rv2608, was 27.8%, 39% and 36.3%, respectively. Truncation of Rv2608 increased sensitivity by approximately 35% in confirmed TB cases. Sensitivity of the fusion construct, TriFu64 increased to 66% with a specificity of 100%. Importantly, tnRv2608 was better able to detect sputum and culture negative patients, and this carried through to the fusion protein. We demonstrate that fusion of Mtb proteins ensures broad sensitivity across disease types, sex and age groups in a Pakistani population.

Plasma Profiles of Inflammatory Markers Associated With Active Tuberculosis in Antiretroviral Therapy-Naive Human Immunodeficiency Virus-Positive Individuals

Background

Diagnosis of tuberculosis (TB) in human immunodeficiency virus (HIV)-coinfected individuals is challenging. We hypothesized that combinations of inflammatory markers could facilitate identification of active TB in HIV-positive individuals.

Methods

Participants were HIV-positive, treatment-naive adults systematically investigated for TB at Ethiopian health centers. Plasma samples from 130 subjects with TB (HIV⁺/TB⁺) and 130 subjects without TB (HIV⁺/TB⁻) were tested for concentration of the following markers: CCL5, C-reactive protein (CRP), interleukin (IL)-6, IL12-p70, IL-18, IL-27, interferon-γ-induced protein-10 (IP-10), procalcitonin (PCT), and soluble urokinase-type plasminogen activator receptor (suPAR). Analyzed markers were then assessed, either individually or in combination, with regard to infection status, CD4 cell count, and HIV ribonucleic acid (RNA) levels.

Results

The HIV⁺/TB⁺ subjects had higher levels of all markers, except IL12p70, compared with HIV⁺/TB⁻ subjects. The CRP showed the best performance for TB identification (median 27.9 vs 1.8 mg/L for HIV⁺/TB⁺ and HIV⁺/TB⁻, respectively; area under the curve [AUC]: 0.80). Performance was increased when CRP was combined with suPAR analysis (AUC, 0.83 [0.93 for subjects with CD4 cell count <200 cells/mm³]). Irrespective of TB status, IP-10 concentrations correlated with HIV RNA levels, and both IP-10 and IL-18 were inversely correlated to CD4 cell counts.

Conclusions

Although CRP showed the best single marker discriminatory potential, combining CRP and suPAR analyses increased performance for TB identification.

Immune responses in the treatment of drug-sensitive pulmonary tuberculosis with phenylbutyrate and vitamin D3 as host directed therapy

Background

We have previously shown that 8 weeks’ treatment with phenylbutyrate (PBA) (500mgx2/day) with or without vitamin D₃ (vitD₃) (5000 IU/day) as host-directed therapy (HDT) accelerated clinical recovery, sputum culture conversion and increased expression of cathelicidin LL-37 by immune cells in a randomized, placebo-controlled trial in adults with pulmonary tuberculosis (TB). In this study we further aimed to examine whether HDT with PBA and vitD₃ promoted clinically beneficial immunomodulation to improve treatment outcomes in TB patients.

Methods

Cytokine concentration was measured in supernatants of peripheral blood mononuclear cells (PBMC) from patients (n = 31/group). Endoplasmic reticulum stress-related genes (GADD34 and XBP1spl) and human beta-defensin-1 (HBD1) gene expression were studied in monocyte-derived-macrophages (MDM) (n = 18/group) from PBMC of patients. Autophagy in MDM (n = 6/group) was evaluated using LC3 expression by confocal microscopy.

Results

A significant decline in the concentration of cytokines/chemokines was noted from week 0 to 8 in the PBA-group [TNF-α (β = − 0.34, 95% CI = − 0.68, − 0.003; p = 0.04), CCL11 (β = − 0.19, 95% CI = − 0.36, − 0.03; p = 0.02) and CCL5 (β = − 0.08, 95% CI = − 0.16, 0.002; p = 0.05)] and vitD₃-group [(CCL11 (β = − 0.17, 95% CI = − 0.34, − 0.001; p = 0.04), CXCL10 (β = − 0.38, 95% CI = − 0.77, 0.003; p = 0.05) and PDGF-β (β = − 0.16, 95% CI = − 0.31, 0.002; p = 0.05)] compared to placebo. Both PBA- and vitD₃-groups showed a decline in XBP1spl mRNA on week 8 (p < 0.03). All treatment groups demonstrated increased LC3 expression in MDM compared to placebo over time (p < 0.037).

Conclusion

The use of PBA and vitD₃ as adjunct therapy to standard TB treatment promoted favorable immunomodulation to improve treatment outcomes.

Trials registration

This trial was retrospectively registered in clinicaltrials.gov, under identifier NCT01580007.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3203-9) contains supplementary material, which is available to authorized users.

Sexual dimorphism in bacterial infections

Background

Sex differences are important epidemiological factors that impact in the frequency and severity of infectious diseases. A clear sexual dimorphism in bacterial infections has been reported in both humans and animal models. Nevertheless, the molecular mechanisms involved in this gender bias are just starting to be elucidated. In the present article, we aim to review the available data in the literature that report bacterial infections presenting a clear sexual dimorphism, without considering behavioral and social factors.

Main body

The sexual dimorphism in bacterial infections has been mainly attributed to the differential levels of sex hormones between males and females, as well as to genetic factors. In general, males are more susceptible to gastrointestinal and respiratory bacterial diseases and sepsis, while females are more susceptible to genitourinary tract bacterial infections. However, these incidences depend on the population evaluated, animal model and the bacterial species. Female protection against bacterial infections and the associated complications is assumed to be due to the pro-inflammatory effect of estradiol, while male susceptibility to those infections is associated with the testosterone-mediated immune suppression, probably via their specific receptors. Recent studies indicate that the protective effect of estradiol depends on the estrogen receptor subtype and the specific tissue compartment involved in the bacterial insult, suggesting that tissue-specific expression of particular sex steroid receptors contributes to the susceptibility to bacterial infections. Furthermore, this gender bias also depends on the effects of sex hormones on specific bacterial species. Finally, since a large number of genes related to immune functions are located on the X chromosome, X-linked mosaicism confers a highly polymorphic gene expression program that allows women to respond with a more expanded immune repertoire as compared with men.

Conclusion

Notwithstanding there is increasing evidence that confirms the sexual dimorphism in certain bacterial infections and the molecular mechanisms associated, further studies are required to clarify conflicting data and to determine the role of specific hormone receptors involved in the gender bias of bacterial infections, as well as their potential as therapeutic targets.

IP-10 Kinetics in the First Week of Therapy are Strongly Associated with Bacteriological Confirmation of Tuberculosis Diagnosis in HIV-Infected Patients

Simple effective tools to monitor the long treatment of tuberculosis (TB) are lacking. Easily measured host derived biomarkers have been identified but need to be validated in larger studies and different population groups. Here we investigate the early response in IP-10 levels (between day 0 and day 7 of TB therapy) to identify bacteriological status at diagnosis among 127 HIV-infected patients starting TB treatment. All participants were then classified as responding or not responding to treatment blindly using a previously described IP-10 kinetic algorithm. There were 77 bacteriologically confirmed cases and 41 Xpert MTB/RIF® and culture negative cases. Most participants had a measurable decline in IP-10 during the first 7 days of therapy. Bacteriologically confirmed cases were more likely to have high IP-10 levels at D0 and had a steeper decline than clinically diagnosed cases (mean decline difference 2231 pg/dl, 95% CI: 897–3566, p = 0.0013). Bacteriologically confirmed cases were more likely to have a measurable decline in IP-10 at day 7 than clinically diagnosed cases (48/77 (62.3%) vs 13/41 (31.7%), p < 0.001). This study confirms the association between a decrease in IP-10 levels during the first week of treatment and a bacteriological confirmation at diagnosis in a large cohort of HIV positive patients.

Early diagnosis and effective treatment regimens are the keys to tackle antimicrobial resistance in tuberculosis (TB): A report from Euroscicon's international TB Summit 2016

To say that tuberculosis (TB) has regained a strong foothold in the global human health and wellbeing scenario would be an understatement. Ranking alongside HIV/AIDS as the top reason for mortality due to a single infectious disease, the impact of TB extends far into socio-economic context worldwide. As global efforts led by experts and political bodies converge to mitigate the predicted outcome of growing antimicrobial resistance, the academic community of students, practitioners and researchers have mobilised to develop integrated, inter-disciplinary programmes to bring the plans of the former to fruition. Enabling this crucial requirement for unimpeded dissemination of scientific discovery was the TB Summit 2016, held in London, United Kingdom. This report critically discusses the recent breakthroughs made in diagnostics and treatment while bringing to light the major hurdles in the control of the disease as discussed in the course of the 3-day international event. Conferences and symposia such as these are the breeding grounds for successful local and global collaborations and therefore must be supported to expand the understanding and outreach of basic science research.

Differences in IgG responses against infection phase related Mycobacterium tuberculosis (Mtb) specific antigens in individuals exposed or not to Mtb correlate with control of TB infection and progression

Tuberculosis (TB) occurs in only 3-10% of Mycobacterium tuberculosis (Mtb) infected individuals, suggesting that natural immunity can contain Mtb infection, although this remains poorly understood. Next to T-cells, a potentially protective role for B-cells and antibodies has emerged recently. However, the Mtb antigens involved remain ill-defined. Here, we investigated in a TB-endemic setting IgG levels against 15 Mtb antigens, representing various phases of Mtb infection and known to be potent human T-cell antigens. IgG levels against ESAT6/CFP10, Rv0440, Rv0867c, Rv1737c, Rv2029c, Rv2215, Rv2389c, Rv3616c and Mtb purified protein derivative (PPD) were higher in TB patients than in endemic and non-endemic controls. The only exception was Rv1733c that was preferentially recognized by antibodies from endemic controls compared to TB patients and non-endemic controls, suggesting a potential correlation with control of TB infection and progression. In patients, IgG levels against Ag85B and Rv2029c correlated with Mtb loads, while immunoglobulins against Rv0440 differed between genders. Our results support the potential role of certain Mtb antigen-(Rv1733c) specific antibodies in the control of TB infection and progression, while other Mtb antigen-specific antibodies correlate with TB disease activity and bacillary loads. The findings for Rv1733c agree with previous T-cell results and have implications for including antibody-mediated immunity in designing new strategies to control TB.