Early Clearance of Mycobacterium tuberculosis: The INFECT Case Contact Cohort Study in Indonesia

BACKGROUND

Early clearance of Mycobacterium tuberculosis is the eradication of infection before an adaptive immune response develops. We aimed to identify host factors associated with early clearance.

METHODS

Indonesian household contacts patients with smear-positive tuberculosis (TB) had an interferon-γ release assay (IGRA) at baseline and 14 weeks later. Early clearance was defined as a persistently negative IGRA. Contact characteristics, exposure, and disease phenotype were assessed for association with a positive IGRA at each time point.

RESULTS

Of 1347 contacts of 462 TB cases, 780 (57.9%) were IGRA positive and 490 (36.3%) were IGRA negative. After 14 weeks, 116 of 445 (26.1%) initially negative contacts were IGRA converters; 317 (71.2%) remained persistently negative. BCG vaccination reduced the risk of a positive baseline IGRA (relative risk [RR], 0.89 [95% confidence interval {CI} .83-.97]; P = .01), and strongly reduced the risk of IGRA conversion (RR, 0.56 [95% CI, .40-.77]; P < .001). BCG protection decreased with increasing exposure (P = .05) and increasing age (P = .004). Risk of IGRA conversion was positively associated with hemoglobin concentration (P = .04).

CONCLUSIONS

A quarter of household TB case contacts were early clearers. Protection against M. tuberculosis infection was strongly associated with BCG vaccination. Lower protection from BCG with increasing M. tuberculosis exposure and age can inform vaccine development.

Early Clearance of Mycobacterium tuberculosis Is Associated With Increased Innate Immune Responses

BACKGROUND

A proportion of tuberculosis (TB) case contacts do not become infected, even when heavily exposed. We studied the innate immune responses of TB case contacts to understand their role in protection against infection with Mycobacterium tuberculosis, termed "early clearance."

METHODS

Indonesian household contacts of TB cases were tested for interferon-γ release assay (IGRA) conversion between baseline and 14 weeks post recruitment. Blood cell populations and ex vivo innate whole blood cytokine responses were measured at baseline and, in a subgroup, flow cytometry was performed at weeks 2 and 14. Immunological characteristics were measured for early clearers, defined as a persistently negative IGRA at 3 months, and converters, whose IGRA converted from negative to positive.

RESULTS

Among 1347 case contacts, 317 were early clearers and 116 were converters. Flow cytometry showed a resolving innate cellular response from 2 to 14 weeks in persistently IGRA-negative contacts but not converters. There were no differences in cytokine responses to mycobacterial stimuli, but compared to converters, persistently IGRA-negative contacts produced more proinflammatory cytokines following heterologous stimulation with Escherichia coli and Streptococcus pneumoniae.

CONCLUSIONS

Early clearance of M. tuberculosis is associated with enhanced heterologous innate immune responses similar to those activated during induction of trained immunity.

Immune cell characteristics and cytokine responses in adult HIV-negative tuberculous meningitis: an observational cohort study

Immunopathology contributes to high mortality in tuberculous meningitis (TBM) but little is known about the blood and cerebrospinal fluid (CSF) immune response. We prospectively characterised the immune response of 160 TBM suspects in an Indonesian cohort, including 67 HIV-negative probable or definite TBM cases. TBM patients presented with severe disease and 38% died in 6 months. Blood from TBM patients analysed by flow cytometry showed lower αβT and γδT cells, NK cells and MAIT cells compared to 26 pulmonary tuberculosis patients (2.4-4-fold, all p < 0.05) and 27 healthy controls (2.7-7.6-fold, p < 0.001), but higher neutrophils and classical monocytes (2.3-3.0-fold, p < 0.001). CSF leukocyte activation was higher than in blood (1.8-9-fold). CSF of TBM patients showed a predominance of αβT and NK cells, associated with better survival. Cytokine production after ex-vivo stimulation of whole blood showed a much broader range in TBM compared to both control groups (p < 0.001). Among TBM patients, high ex-vivo production of TNF-α, IL-6 and IL-10 correlated with fever, lymphocyte count and monocyte HLA-DR expression (all p < 0.05). TBM patients show a strong myeloid blood response, with a broad variation in immune function. This may influence the response to adjuvant treatment and should be considered in future trials of host-directed therapy.

Decreased whole blood RNA expression of cathelicidin in HIV-infected heroin users in Bandung, Indonesia

The antimicrobial peptide cathelicidin is critical in killing pathogens by innate immune cells, including Mycobacterium tuberculosis and Candida albicans. These pathogens often cause infections in opioid users, a risk that is greatly increased with concurrent human immunodeficiency virus (HIV) infection. Therefore, we examined the association between opioid use and cathelicidin in HIV-infected subjects from Bandung, Indonesia. The following three groups of HIV-infected individuals were included: (i) Active drug users: used heroin in the last 30 days; (ii) Methadone clients: received methadone maintenance therapy in the last 30 days; and (iii)

CONTROLS

never used opioids or did not use opioids in the year preceding inclusion. In addition to interviews, blood samples were taken to examine the RNA expression of cathelicidin. We found that the RNA expression of cathelicidin was significantly decreased (p=0.007) in heroin users, compared with controls. Opioids are associated with immunosuppression, and cathelicidin could be an important factor in this association. However, more research is needed to examine the direct effects of decreased cathelicidin levels.

Virological failure and drug resistance during first line anti-retroviral treatment in Indonesia

The virological response and development of drug resistance during first-line anti-retroviral treatment (ART) were studied in Indonesia where the majority of patients infected with HIV have a history of injecting drug use, which is often linked with lower treatment adherence and development of drug-resistance. As many as 575 patients starting ART between September 2007 and March 2010 in Hasan Sadikin Hospital Bandung were followed prospectively. Clinical and laboratory monitoring was performed every 6 months. Plasma samples with HIV-RNA ≥ 400 copies/ml were examined for drug resistance mutations. Most patients were male (72.3%), 59.7% had a history of injecting drug use, and the median CD4+ cells count before start of ART was 35 cells/mm(3) (IQR 10-104). From 438 HIV patients with HIV-RNA measurements, 40 (9.1%) subjects had HIV-RNA ≥ 400 copies/ml after 24 weeks (median follow-up 16 (IQR 8-25) months). Of these failing patients 16 (47%) subjects had drug resistance mutations, predominantly M184V (35.3%), Y181C (23.5%), K103N (11.7%), and TAMs (11.7%). A history of treatment discontinuation ≥ 1 month, reported by 5.3% (23) of patients, was strongly associated with virological failure (adjusted OR 12.64, 95% CI 4.51-35.41); and a history of injecting drug use was not (OR 0.75, 95% CI 0.38-1.46). This is the largest and most systematic evaluation of virological response to first line ART in Indonesia. Patients in this cohort responded well to first line ART, with low rates of virological failure and drug resistance. A history of injecting drug use should not be a reason to withhold ART in this setting.

Total lymphocyte count is a reliable surrogate marker for CD4 cell counts after the first year of antiretroviral therapy: data from an Indonesian cohort study

Many studies have evaluated the total lymphocyte count (TLC) as a cheap surrogate marker for CD4 cells in HIV-infected patients not receiving antiretroviral therapy (ART). We assessed whether TLC can replace CD4 cell counts in evaluating the immunological response to ART. In a cohort of patients in Indonesia TLC, if measured after at least 1-year ART, correctly identified patients with <200 CD4 cells, and reliably excluded immunological failure, obviating the need for CD4 cell measurement in 43% of patients.

Total lymphocyte count is a good marker for HIV-related mortality and can be used as a tool for starting HIV treatment in a resource-limited setting

OBJECTIVES

Total lymphocyte counts (TLC) may be used as an alternative for CD4 cell counts to monitor HIV infection in resource-limited settings, where CD4 cell counts are too expensive or not available.

METHODS

We used prospectively collected patient data from an urban HIV clinic in Indonesia. Predictors of mortality were identified via Cox regression, and the relation between TLC and CD4 cell counts was calculated by linear regression. Receiver operating characteristics (ROC) curves were used to choose the cut-off values of TLC corresponding with CD4 cell counts <200 and ≤350 cells/μl. Based on these analyses, we designed TLC-based treatment algorithms.

RESULTS

Of 889 antiretroviral treatment (ART)-naïve subjects included, 66% had CD4 cell counts <200 and 81% had 350 ≤ cells/μl at baseline. TLC and CD4 cell count were equally strong predictors of mortality in our population, where ART was started based on CD4 cell count criteria. The correlation coefficient (R) between TLC and √CD4 was 0.70. Optimal cut-off values for TLC to identify patients with CD4 cell counts <200 and ≤350 cells/μl were 1500 and 1700 cells/μl, respectively. Treatment algorithms based on a combination of TLC, gender, oral thrush, anaemia and body mass index performed better in terms of predictive value than WHO staging or TLC alone. In our cohort, such an algorithm would on average have saved $14.05 per patient.

CONCLUSION

Total lymphocyte counts is a good marker for HIV-associated mortality. Simple algorithms including TLC can prioritize patients for HIV treatment in a resource-limited setting, until affordable CD4 cell counts will be universally available.