Interleukin 1-Beta (IL-1β) Production by Innate Cells Following TLR Stimulation Correlates With TB Recurrence in ART-Treated HIV-Infected Patients

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.

Decreased IL-1 β Secretion as a Potential Predictor of Tuberculosis Recurrence in Individuals Diagnosed with HIV

Background: The mechanisms of the formation of immunological competence against tuberculosis (TB), and especially those associated with HIV co-infection, remain poorly understood. However, there is an urgent need for risk recurrence predictive biomarkers, as well as for predictors of successful treatment outcomes. The goal of the study was to identify possible immunological markers of TB recurrence in individuals with HIV/TB co-infection. Methods: The plasma levels of IFN-γ, TNF-α, IL-10, and IL-1β (cytokines which play important roles in the immune activation and protection against Mycobacterium tuberculosis) were measured using ELISA EIA-BEST kits. The cytokine concentrations were determined using a standard curve obtained with the standards provided by the manufacturer of each kit. Results: A total of 211 individuals were enrolled in the study as follows: 62 patients with HIV/TB co-infection, 52 with HIV monoinfection, 52 with TB monoinfection, and 45 healthy donors. Out of the 62 patients with HIV/TB, 75.8% (47) of patients were newly diagnosed with HIV and TB, and 24.2% (15) displayed recurrent TB and were newly diagnosed with HIV. Decreased levels of IFN-γ, TNF-α, and IL-10 were observed in patients with HIV/TB when compared with HIV and TB patients. However, there was no difference in IFN-γ, TNF-α, or IL-10 secretion between both HIV/TB groups. At the same time, an almost 4-fold decrease in Il-1β levels was detected in the HIV/TB group with TB recurrence when compared with the HIV/TB group (p = 0.0001); a 2.8-fold decrease when compared with HIV patients (p = 0.001); and a 2.2-fold decrease with newly diagnosed TB patients (p = 0.001). Conclusions: Significantly decreased Il-1β levels in HIV/TB patients' cohort with secondary TB indicate that this cytokine can be a potential biomarker of TB recurrence.

Increased Levels of Caspase-1 and IL-1β Among Adults With Persistent Immune Activation After 12 Years of Suppressive Antiretroviral Therapy in the Infectious Diseases Institute HIV Treatment Cohort

Background

We sought evidence of activated pyroptosis and the inflammasome pathways among human immunodeficiency virus (HIV)-infected adults after 12 years of suppressive antiretroviral therapy (ART) and persistent immune activation in the Infectious Diseases Institute HIV treatment cohort in Uganda.

Methods

In a cross-sectional study, using peripheral blood mononuclear cells of HIV-infected individuals with high and low immune activation (CD4/CD8+CD38+HLA-DR+ cells) relative to HIV-negative reference group, caspase-1 expression was measured using flow cytometry and plasma interleukin 18 and interleukin 1β (IL-1β) levels using enzyme-linked immunosorbent assay.

Results

There was higher expression of caspase-1 by CD4 T cells of ART-treated individuals with high immune activation relative to those with lower immune activation (P = .04). Similarly, plasma levels of IL-1β were higher among ART-treated individuals with high immune activation levels relative to those with low immune activation levels (P = .009). We observed a low positive correlation between caspase-1 expression by CD4/CD8 T cells and immune activation levels (r= 0.497 and r= 0.329, respectively).

Conclusions

Caspase-1 and IL-1β were high among individuals with high immune activation despite 12 years of suppressive ART. There is a need to further understand the role of persistent abortive infection and the latent HIV reservoir characteristics as drivers of persistent activation and inflammation and to subsequently intervene to prevent the complications of chronic immune activation during long-term ART.

Helper T cell bias following tuberculosis chemotherapy identifies opportunities for therapeutic vaccination to prevent relapse

Therapeutic vaccines have promise as adjunctive treatment for tuberculosis (TB) or as preventives against TB relapse. An important development challenge is the limited understanding of T helper (Th) cell roles during these stages of disease. A murine model of TB relapse was used to identify changes in Th populations and cytokine microenvironment. Active TB promoted expansion of Th1, Th2, Th17, and Th22 cells and cytokines in the lung. Following drug therapy, pulmonary Th17 and Th22 cells contracted, Th1 cells remained elevated, while Th cells producing IL-4 or IL-10 expanded. At relapse, Th22 cells failed to re-expand in the lung despite a moderate re-expansion of Th1 and Th17 cells and an increase in Th cytokine polyfunctionality. The dynamics of Th populations further differed by tissue compartment and disease presentation. These outcomes identify immune bias by Th subpopulations during TB relapse as candidate mechanisms for pathogenesis and targets for therapeutic vaccination.

Single-Cell Transcriptomics of Mtb/HIV Co-Infection

Tuberculosis (TB) and Human Immunodeficiency Virus (HIV) co-infection continues to pose a significant healthcare burden. HIV co-infection during TB predisposes the host to the reactivation of latent TB infection (LTBI), worsening disease conditions and mortality. There is a lack of biomarkers of LTBI reactivation and/or immune-related transcriptional signatures to distinguish active TB from LTBI and predict TB reactivation upon HIV co-infection. Characterizing individual cells using next-generation sequencing-based technologies has facilitated novel biological discoveries about infectious diseases, including TB and HIV pathogenesis. Compared to the more conventional sequencing techniques that provide a bulk assessment, single-cell RNA sequencing (scRNA-seq) can reveal complex and new cell types and identify more high-resolution cellular heterogeneity. This review will summarize the progress made in defining the immune atlas of TB and HIV infections using scRNA-seq, including host-pathogen interactions, heterogeneity in HIV pathogenesis, and the animal models employed to model disease. This review will also address the tools needed to bridge the gap between disease outcomes in single infection vs. co-infection. Finally, it will elaborate on the translational benefits of single-cell sequencing in TB/HIV diagnosis in humans.

Association of Toll-Like Receptor Gene Polymorphisms with Tuberculosis in HIV-Positive Participants

Genetic factors in the HIV-background may play a significant role in the susceptibility to secondary diseases, like tuberculosis, which is the leading cause in mortality of HIV-positive people. Toll-like receptors (TLRs) are considered to be receptors for adaptive immunity, and polymorphisms in TLR genes can influence the activity of the immune response to infection. We conducted a case-control study of the association of TLR gene polymorphisms with the risk of tuberculosis coinfection in a multi-country sample of HIV-positive participants. Our study revealed certain associations between TLR4 and TLR6 polymorphisms and HIV-tuberculosis coinfection. We also found that the analyzed TLR1 and TLR4 polymorphisms were linked with the decline in CD4+ cell count, which is a predictor of disease progression in HIV-infected individuals. Our findings confirm that TLR gene polymorphisms are factors that may contribute to development of HIV-tuberculosis coinfection. However, the essence of the observed associations remains unclear, since it can also include both environmental factors and epigenetic mechanisms of gene expression regulation.

Advances on the Role and Applications of Interleukin-1 in Tuberculosis

Interleukin-1 (IL-1) is a key player in the immune response to pathogens due to its role in promoting inflammation and recruiting immune cells to the site of infection. In tuberculosis (TB), tight regulation of IL-1 responses is critical to ensure host resistance to infection while preventing immune pathology. In the mouse model of Mycobacterium tuberculosis infection, both IL-1 absence and overproduction result in exacerbated disease and mortality. In humans, several polymorphisms in the IL1B gene have been associated with increased susceptibility to TB. Importantly, M. tuberculosis itself has evolved several strategies to manipulate and regulate host IL-1 responses for its own benefit. Given all this, IL-1 appears as a promising target for host-directed therapies in TB. However, for that to succeed, more detailed knowledge on the biology and mechanisms of action of IL-1 in vivo, together with a deep understanding of how host-M. tuberculosis interactions modulate IL-1, is required. Here, we discuss the most recent advances in the biology and therapeutic potential of IL-1 in TB as well as the outstanding questions that remain to be answered.

ILC2s induce adaptive Th2-type immunity in different stages of tuberculosis through the Notch-GATA3 pathway

The study is to investigate the roles of group 2 innate lymphoid cells (ILC2s) in different courses of tuberculosis (TB). Serum and PBMCs were respectively isolated from the TST negative, LTBI (latent TB infection), ATB (active TB) and RTB (recurrent TB) patients. Flow cytometry was used to detect Th1, Th2 and ILC2s in the peripheral blood. The mRNA and protein levels of GATA3, RORα, CRTH2, Hes1, Notch1, NF-κB, and ID2 were detected by qRT-PCR and Western blotting. ILC2 cells from ATB and RTB patients were stimulated with rJagged2 or DAPT in vitro, and co-cultured with CD4⁺ T cells from TST negative group. ELISA was used to detect cytokine levels. The results showed that compared with the TST negative or LTBI group, Th2 cells and serum IL-4 in ATB group increased dramatically, accompanied by an increase of Th2/Th1 ratio in ATB patients, especially in RTB group. However, ILC2s in the ATB and RTB group increased significantly, along with increased GATA3, RORα, and CRTH2 levels. After rJagged2 stimulation in vitro, the levels of Hes1, Notch1, NF-κB, RORα, GATA3 and ID2 and those of IL-4, IL-5 and IL-13 were significantly increased. These effects were abrogated by DAPT treatment. Then, ILC2s, especially those from RTB patients, induced Th2-type immune response after co-culturing with CD4⁺ T cells. In conclusion, our results suggest that ILC2s may promote Th2-type immune response in different stages of TB via the Notch-GATA3 pathway.

Herbal melanin induces interleukin-1β secretion and production by human THP-1 monocytes via Toll-like receptor 2 and p38 MAPK activation

Herbal melanin (HM), extracted from Nigella sativa, is known for its immunogenic properties through the modulation of cytokine production via Toll-like receptor (TLR)4. TLRs play a crucial role in the host defense through the regulation of innate and adaptive immune responses. However, the potential effect of HM on the production of interleukin-1β (IL-1β), the main immunoregulatory cytokine secreted by activated monocytes, has not been reported. The present study aimed to investigate the effects of HM on IL-1β secretion and production, detected by enzyme-linked immunosorbent assay, western blotting and mRNA expression monitored by reverse transcription-PCR, in human monocytes and a monocytic cell line, THP-1. Signaling pathways involved in the HM-induced IL-1β production was investigated in the THP-1 cells. It was shown that HM upregulated the IL-1β mRNA in the THP-1 cells and induced the secretion of IL-1β in the monocytes and THP-1 cells, in a dose-dependent manner, compared to the untreated cells. HM increased the protein expression of IL-1β, TLR2, the main receptor for IL-1β production, and activated p38 mitogen-activated protein kinase (MAPK), a key mediator for stress-induced IL-1β gene expression. The blockade of the p38 MAPK pathway, with the pharmacological inhibitor SB202190, and TLR2 receptor with a neutralization antibody, resulted in the decrease of HM-induced IL-1β production in THP-1 cells. The TLR4 receptor blockade also decreased HM-induced IL-1β production, but to a lesser extent than TLR2 blockade. In conclusion, the present study demonstrated that HM stimulates IL-1β production in monocytes and THP-1 cells, in a TLR2/p38 MAPK pathway-dependent manner, suggesting promising immunoregulatory potentials of HM against inflammatory-associated diseases.

The Effect of Antiretroviral Therapy on IL-6, IL-1β, TNF-α, IFN-γ Levels and their Relationship with HIV-RNA and CD4+ T Cells in HIV Patients

BACKGROUND

Serum cytokine levels over the course of HIV infection usually increase with immunosuppression and decrease after antiretroviral treatment (ART).

OBJECTIVES

The aim of the study is to compare cytokine levels between HIV-infected patients (HIP) and controls and investigate the relationship between CD4+T cell count, HIV-RNA levels, and cytokine levels.

METHODS

The study subjects comprised ART-naive HIP (n=30) with no comorbidities and age-and sex-matched healthy controls. We measured levels of IL-6, IL-1β, TNF-α, and IFN-γ in serum samples of HIP at the beginning and at month 6 of ART and in controls.

RESULTS

The mean age of the study subjects was 38.7 ±10.3 years, with men making up 86.7% of the study subjects (n=26). IL-6, IL-1β, and TNF-α levels were significantly higher in both ART-naive (p<0.001, p=0.002, p=0.001) and ART-experienced HIP (p<0.001) than controls. The IFN-γ level was lower in both ART-naive and ART-experienced HIP compared to controls (p=0.082 and p=0.002). There was a positive correlation between the CD4+T cell count and serum concentration of IFN- γ(r=0.320, p<0.05). While the serum IFN-γ concentration showed a negative correlation with the HIVRNA level(r=-0.412, p<0.001), the serum IL-1β, IL-6, and TNF-α concentrations showed a positive correlation with the HIV-RNA level (r=0.349, p<0.001; r:0.54, p<0.001; r:0.438, p<0.00).

CONCLUSION

Although serum concentrations of IL-6, IL-1β and TNF-α showed a significant decrease after ART, they were still significantly higher than the controls. IFN-γ responded differently to ART compared to the other cytokines, indicating that it may play a distinct and important role in the pathogenesis of HIV infection.

BCG Against SARS-CoV-2: Second Youth of an Old Age Vaccine?

The sudden outbreak of the COVID-19 pandemic, caused by SARS-CoV-2, has put the whole world into a difficult situation, asking for the immediate development of therapeutics and vaccines against the disease. Bacillus Calmette–Guérin (BCG), an attenuated strain of Mycobacterium bovis, has been administered for decades in many countries against tuberculosis. Today, when a solution against SARS-CoV-2 is urgently needed, the BCG vaccine has again come into the limelight owing to its earlier prevention of non-specific diseases. Data suggest a higher mortality rate of COVID-19 in non-BCG vaccinated countries, whereas the nations opting for BCG immunization have a comparatively lower mortality rate. The BCG vaccine is known to induce ‘trained immunity’ and generate ‘non-specific’ heterologous immune responses. It can confer anti-viral immunity by eliciting the production of pro-inflammatory cytokines, IL-6, TNF-α, IFN-γ, and IL-1β. Though the initial results look promising, a long trail still needs to be followed to avoid false promises. The accuracy of nationwide data, the role of an already activated immune system against ‘cytokine storms’, optimization and timing of vaccine dosage, and balancing demand-supply are some of the relevant issues that must be resolved before reaching a final conclusion.

Monocyte Dysfunction, Activation, and Inflammation After Long-Term Antiretroviral Therapy in an African Cohort

BACKGROUND

Monocyte dysfunction may persist during antiretroviral therapy (ART).

METHODS

Frozen peripheral blood mononuclear cells of 30 human immunodeficiency virus (HIV)-infected ART-treated adults with sustained viral suppression and CD4 counts ≥500 cells/µL were consecutively analyzed for monocyte phenotypes and function.

RESULTS

Nonclassical monocytes (CD14+, CD16++), interleukin (IL)-1β production, and expression of CD40 and CD86 were lower among ART-treated HIV-infected adults relative to age-matched HIV-negative adults (P = .01, P = .01, and P = .02, respectively). Intestinal fatty acid-binding protein, IL6, and soluble CD14 were higher among HIV-infected adults relative to HIV-negative adults (P = .0002, P = .04, and P = .0017, respectively).

CONCLUSIONS

Further investigation is required to understand drivers of persistent monocyte activation and dysfunction.

Effect of video-assisted thoracoscopic surgery on pain stress indicators NO, IL-1β and IL-6 in the treatment of mediastinal tumor in children

This study aimed to investigate the effect of video-assisted thoracoscopic surgery (VATS) on pain stress indicators nitric oxide (NO), interleukin-1β (IL-1β) and IL-6 in the treatment of mediastinal tumor in children, so as to explore the clinical application value of this surgery. A retrospective analysis was performed on 82 children with mediastinal tumor undergoing operation in Children's Hospital Affiliated to Zhengzhou University from January 2012 to January 2016. Among them, 48 children undergoing VATS were enrolled as an observation group, and 34 children undergoing conventional thoracotomy were enrolled as a control group. Enzyme-linked immunosorbent assay (ELISA) was used to detect the preoperative and postoperative expression levels of NO, IL-1β and IL-6. The intraoperative clinical data, postoperative pain degree and infection rate were observed and recorded in real time, and then compared between the two groups. Before operation (T₀), there were no statistically significant differences between the two groups in serum NO, IL-1β and IL-6 expression levels, which were lower in the observation group than those in the control group at 12 h (T₁) and 24 h (T₂) after operation (P<0.05). The visual analog scale (VAS) score in the observation group was lower than that in the control group at T₁ (P<0.05). Compared with the control group, the largest blade opening, intraoperative blood loss, drainage duration and postoperative pain degree were significantly improved in the observation group. The postoperative infection rate was 4.17% in the observation group, significantly lower than 17.64% in the control group. VATS is effective for postoperative pain stress indicators and infection control in children with mediastinal tumor, which is therefore more suitable for children with the disease and has a higher clinical value.

Increased vitamin D receptor expression from macrophages after stimulation with M. tuberculosis among persons who have recovered from extrapulmonary tuberculosis

BACKGROUND

Independent of HIV infection, extrapulmonary TB (EPTB) risk is increased in women, persons of black race or foreign birth, and by genetic variants in vitamin D receptor (VDR), interleukin-1 beta (IL-1β), and toll-like receptor (TLR)-2; functional correlates are unclear. We evaluated macrophage expression of VDR, TLR2, cathelicidin, and TNF-α, and production of IL-1β in HIV-seronegative persons with previous EPTB, previous pulmonary TB, latent M. tuberculosis infection, and uninfected TB contacts. Persons with previous pleural TB were excluded due to enhanced immune responses at the site of disease.

METHODS

Macrophages were stimulated with TLR-2 agonist M. tuberculosis lipoprotein (LpqH), live and gamma-irradiated M. tuberculosis.

RESULTS

M. tuberculosis - infected macrophages from persons with previous EPTB had increased VDR expression (29.17 relative value unit increase in median expression vs. uninfected contacts, after adjusting for foreign-born status; P = 0.02). Macrophages from persons with previous EPTB had a 38.88 μg/mL increase in median IL-1β production after stimulation with LpqH compared to uninfected contacts (P = 0.01); the effect was similar (44.99 μg/mL) but not statistically significant after controlling for foreign-born status. Median 25-hydroxyvitamin D levels were low but not significantly different between groups.

CONCLUSIONS

There was increased macrophage expression of VDR after stimulation with live M. tuberculosis in persons with previous extrapulmonary TB. If post-treatment VDR expression reflects expression prior to disease, it may identify persons at risk for extrapulmonary TB.

Plasma Cytokine Predictors of Tuberculosis Recurrence in Antiretroviral-Treated Human Immunodeficiency Virus-infected Individuals from Durban, South Africa

Background

Immune correlates of tuberculosis (TB) risk in populations infected with human immunodeficiency virus (HIV) remain understudied, despite HIV being associated with a high burden of TB disease. Here we describe plasma cytokine correlates of TB recurrence in a well-characterized cohort of HIV-infected individuals on antiretroviral therapy (ART) with a history of prior TB cure.

Methods

Study participants were drawn from a prospective cohort study initiated at the conclusion of a randomized clinical trial in which individuals presented with untreated HIV infection and active pulmonary TB. At baseline, ART was initiated, and TB successfully cured. Participants were screened for TB recurrence quarterly for up to 4 years. TB recurrent cases (n = 63) were matched to controls (n = 123) on sex, study arm assignment in the original trial, and month of enrollment with a subset of cases sampled longitudinally at several time-points.

Results

Three cytokines were associated with increased rates of TB recurrence in univariate models: interleukin 6 (IL6) (odds ratio [OR] 2.66, 95% confidence interval [CI] 1.34-5.28, P = .005), IP10 (OR 4.62, 95% CI 1.69-12.65, P = .003), monokine induced by IFN-γ (MIG) (OR 3.11, 95% CI 1.10-8.82, P = .034). Conversely, interferon β (IFNβ) was associated with decreased TB risk (OR 0.34, 95% CI 0.13-0.87, P = .025). Following multivariate analyses adjusting for covariates IL6, interleukin 1β (IL1β), and interleukin 1Rα (IL1Rα) were associated with increased risk and IFNβ with decreased TB risk. Longitudinal analysis showed that levels of many TB-associated markers, including IL6, IP10, sCD14, and interferon γ (IFNγ) are reduced following TB treatment.

Conclusion

These data show that TB recurrence, in HIV-infected individuals on ART is predicted by biomarkers of systemic inflammation, many of which are implicated in more rapid HIV disease progression.

Clinical Trials Registration

NCT 01539005.

Tuberculous meningitis is associated with higher cerebrospinal HIV-1 viral loads compared to other HIV-1-associated meningitides

To gain a better understanding of the immunopathogenesis of tuberculous meningitis (TBM) and identify potential diagnostic biomarkers that may discriminate TBM from other HIV-1-associated meningitides, we assessed HIV-1 viral load levels, drug resistance patterns in antiretroviral therapy (ART)-experienced patients with persistent viremia and soluble immunological analytes in peripheral blood and cerebrospinal fluid (CSF) of HIV-1 infected patients with TBM versus other meningitides. One hundred and three matched blood and CSF samples collected from HIV-1 infected patients with TBM or other meningitides presenting at a hospital in Durban, South Africa, from January 2009 to December 2011 were studied. HIV-1 RNA and 28 soluble immunological potential biomarkers were quantified in blood plasma and CSF. Viremic samples were assessed for HIV-1 drug resistance mutations. There were 16 TBM, 46 probable TBM, 35 non-TBM patients, and six unclassifiable patients. TBM and non-TBM patients did not differ in median plasma viral load but TBM patients had significantly higher median CSF viral load than non-TBM participants (p = 0.0005). No major drug resistance mutations were detected in viremic samples. Interleukin (IL)-1β, IL-17, platelet derived growth factor (PDGF)-BB, granulocyte colony stimulating factor (G-CSF) and cathelicidin were significantly elevated in the CNS of TBM participants compared to other patients although these associations were lost after correction for false discovery. Our data suggest that TB co-infection of the CNS is associated with enhanced localized HIV-1 viral replication but none of the evaluated soluble immunological potential biomarkers could reliably distinguish TBM from other HIV-associated meningitides.

Immunological non-response and low hemoglobin levels are predictors of incident tuberculosis among HIV-infected individuals on Truvada-based therapy in Botswana

Background

There is a high burden of tuberculosis (TB) in HIV antiretroviral programmes in Africa. However, few studies have looked at predictors of incident TB while on Truvada-based combination antiretroviral therapy (cART) regimens.

Methods

We estimated TB incidence among individuals enrolled into an observational cohort evaluating the efficacy and tolerability of Truvada-based cART in Gaborone, Botswana between 2008 and 2011. We used Cox proportional hazards regressions to determine predictors of incident TB.

Results

Of 300 participants enrolled, 45 (15%) had a diagnosis of TB at baseline. During 428 person-years (py) of follow-up, the incidence rate of TB was 3.04/100py (95% CI, 1.69–5.06), with 60% of the cases occurring within 3 months of ART initiation. Incident cases had low baseline CD4+ T cell counts (153cells/mm³ [Q1, Q3: 82, 242]; p = 0.69) and hemoglobin levels (9.2g/dl [Q1, Q3: 8.5,10.1]; p<0.01). In univariate analysis, low BMI (HR = 0.73; 95% CI 0.58–0.91; p = 0.01) and hemoglobin levels <8 g/dl (HR = 10.84; 95%CI: 2.99–40.06; p<0.01) were risk factors for TB. Time to incident TB diagnosis was significantly reduced in patients with poor immunological recovery (p = 0.04). There was no association between baseline viral load and risk of TB (HR = 1.75; 95%CI: 0.70–4.37).

Conclusion

Low hemoglobin levels prior to initiation of ART are significant predictors of incident tuberculosis. Therefore, there is potential utility of iron biomarkers to identify patients at risk of TB prior to initiation on ART. Furthermore, additional strategies are required for patients with poor immunological recovery to reduce excess risk of TB while on ART.