Interferon Gamma Release Assay and Tuberculin Skin Test Performance in Pregnant Women Living With and Without HIV

Diminished Mycobacterium tuberculosis-specific T-cell Responses During Pregnancy in Women With HIV and Receiving Isoniazid Preventive Therapy

Background

Pregnancy increases Mycobacterium tuberculosis (Mtb) reactivation risk and alters immune responses. We assessed Mtb-specific CD4+ T-cell responses in pregnant women with HIV (WLHIV) and without, including those receiving isoniazid preventive therapy (IPT).

Methods

We measured adaptive immune responses from 33 participants (HIV+ 21, HIV- 12) with positive interferon-gamma release assay during pregnancy (20-34 weeks' gestation), 6 weeks, and 12 months postpartum by intracellular cytokine staining. We measured overall responses using COMPASS and made comparisons by nonparametric analysis of variance.

Result

We observed diminished Mtb-specific CD4+ T-cell responses in WLHIV during pregnancy versus 12 months postpartum (COMPASS median functional score [FS] .009 vs 0.12, P = .03). WLHIV who received IPT (n = 8) during concurrent pregnancy had attenuated Mtb-specific CD4+ T-cell responses during pregnancy versus 12 months postpartum (median FS 8.3 × 10-7 vs 0.13, P = .02), but WLHIV who did not receive IPT during pregnancy had similar responses in pregnancy and postpartum. Mtb-specific CD8+ FS was increased postpartum in all groups. We found preexisting Mtb-specific CD4+ T-cell responses in participants who converted interferon-gamma release assay tests postpartum (n = 10).

Conclusions

Pregnant WLHIV, especially those on IPT, showed reduced Mtb-specific CD4+ T-cell responses. Understanding the impact of pregnancy on Mtb-specific T-cell responses may improve diagnostic approaches.

Mycobacterium tuberculosis infection in pregnancy: A systematic review

Pregnancy may be associated with risk of developing tuberculosis (TB) in those infected with Mycobacterium tuberculosis (Mtb). The perinatal period could provide opportunities for targeted screening and treatment. This study aims to synthesise published literature on Mtb infection in pregnancy, relating to prevalence, natural history, test performance, cascade of care, and treatment. We searched Ovid MEDLINE, Embase+Embase Classic, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) on October 3, 2023, and 47 studies met the inclusion criteria. The prevalence of Mtb infection was as high as 57.0% in some populations, with rates increasing with maternal age and in women from high TB-incidence settings. Five studies quantified perinatal progression from Mtb infection to active TB disease, with two demonstrating increased risk compared to non-pregnant populations (IRR 1.3-1.4 during pregnancy and IRR 1.9-2 postpartum). Concordance between Tuberculin Skin Test (TST) and Interferon Gamma-Release Assay (IGRA) ranged from 49.4%-96.3%, with k-values of 0.19-0.56. High screening adherence was reported, with 62.0-100.0% completing antenatal TST and 81.0-100.0% of those positive having chest radiograph. Four studies of TB preventative treatment (TPT) did not find a significant association with serious adverse events. The antenatal period could provide opportunities for contextualised Mtb infection screening and treatment. As women with increased age and from high TB-incidence settings demonstrate higher prevalence and risk of disease, this cohort should be prioritised. TPT appears safe and feasible; however, further studies are needed to optimise algorithms, ensuring pregnant and postpartum women can make evidence-informed decisions for effective TB prevention.

Tuberculosis Preventive Treatment for Pregnant People With Human Immunodeficiency Virus in South Africa: A Modeling Analysis of Clinical Benefits and Risks

BACKGROUND

Although prior studies of tuberculosis-preventive treatment (TPT) for pregnant people with human immunodeficiency virus (PPWH) report conflicting adverse pregnancy outcome (APO) risks, international guidelines recommend TPT for PPWH.

METHODS

We used a microsimulation model to evaluate 5 TPT strategies among PPWH receiving antiretroviral therapy in South Africa: No TPT; 6 months of isoniazid (6H) or 3 months of isoniazid-rifapentine (3HP) during pregnancy (Immediate 6H or Immediate 3HP) or post partum (Deferred 6H or Deferred 3HP). The primary outcomes were maternal, fetal/infant, and combined deaths from causes potentially influenced by TPT (maternal tuberculosis, maternal hepatotoxicity, stillbirth, low birth weight [LBW], and infant tuberculosis). Tuberculosis during pregnancy confers 250% and 81% higher modeled risks of stillbirth and LBW, respectively. In lower-risk or higher-risk scenarios, immediate TPT confers 38% lower or 92% higher risks of stillbirth and 16% lower or 35% higher risks of LBW.

RESULTS

Immediate TPT would minimize deaths among PPWH. When TPT confers higher stillbirth and LBW risks, immediate TPT would produce the most combined maternal and fetal/infant deaths, even with low maternal CD4 cell count and high tuberculosis incidence. If immediate TPT yields a <4% or <20% increase in stillbirth or LBW, immediate TPT would produce fewer combined deaths than deferred TPT (sensitivity analysis range, <2%-22% and <11%-120%, respectively).

CONCLUSIONS

If APO risks are below identifiable thresholds, TPT during pregnancy could decrease combined maternal and fetal/infant deaths. Given uncertainty around isoniazid's risks, and the low threshold at which APO risks could outweigh benefits from tuberculosis deaths averted, studies of newer TPT regimens among PPWH are warranted to inform guidelines.

Maternal breastfeeding and education impact infant growth and development more than in-utero HIV/antiretroviral therapy exposure in context of universal antiretroviral therapy

BACKGROUND

Exposure to HIV and antiretroviral therapy (ART) in utero may influence infant growth and development. Most available evidence predates adoption of universal ART (Option B+ ART regimens). In a recent cohort, we compared growth and development in HIV-exposed uninfected (HEU) to HIV-unexposed (HUU) infants.

DESIGN

Prospective cohort study: data from Impact of Maternal HIV on Mycobacterium Tuberculosis Infection among Peripartum Women and their Infants (MiTIPS) in Western Kenya.

METHODS

Women were enrolled during pregnancy. Mother-infant pairs were followed until 24 months postpartum. We used multivariable linear mixed-effects models to compare growth rates [weight-for-age z score (WAZ) and height-for-age z score (HAZ)] and multivariable linear regression to compare overall development between HEU and HUU children.

RESULTS

About 51.8% (184/355) of the infants were HEU, 3.9% low birthweight (<2.5 kg), and 8.5% preterm (<37 gestational weeks). During pregnancy, all mothers of HEU received ART; 67.9% started ART prepregnancy, and 87.3% received 3TC/FTC, TDF, and EFV. In longitudinal analyses, HEU children did not differ significantly from HUU in growth or development ( P  > 0.05 for all). In the combined HEU/HUU cohort, higher maternal education was associated with significantly better growth and development: WAZ [ β  = 0.18 (95% CI 0.01-0.34)], HAZ [ β  = 0.26 (95% CI 0.04-0.48)], and development [ β  = 0.24 (95% CI 0.02-0.46)]. Breastfeeding was associated with significantly better HAZ [ β =0.42 (95% CI 0.19-0.66)] and development [ β  =0.31 (95% CI 0.08-0.53)].

CONCLUSION

HEU children in the setting of universal maternal ART had a similar growth trajectory and development to HUU children. Breastfeeding and maternal education improved children's weight, height, and overall development irrespective of maternal HIV status.

Maternal HIV Status and Risk of Infant Mycobacterium tuberculosis Infection as Measured by Tuberculin Skin Test

BACKGROUND

The effect of maternal HIV on infant Mycobacterium tuberculosis (Mtb) infection risk is not well-characterized.

METHODS

Pregnant women with/without HIV and their infants were enrolled in a longitudinal cohort in Kenya. Mothers had interferon gamma-release assays (QFT-Plus) and tuberculin skin tests (TST) at enrollment in pregnancy; children underwent TST at 12 and 24 months of age. We estimated the incidence and correlates of infant TST-positivity using Cox proportional hazards regression.

RESULTS

Among 322 infants, 170 (53%) were HIV-exposed and 152 (47%) were HIV-unexposed. Median enrollment age was 6.6 weeks [interquartile range (IQR): 6.1-10.0]; most received Bacillus Calmette-Guerin (320, 99%). Thirty-nine (12%) mothers were TST-positive; 102 (32%) were QFT-Plus-positive. Among HIV-exposed infants, 154 (95%) received antiretrovirals for HIV prevention and 141 (83%) of their mothers ever received isoniazid preventive therapy (IPT). Cumulative 24-month infant Mtb infection incidence was 3.6/100 person-years (PY) [95% confidence interval (CI): 2.4-5.5/100 PY]; 5.4/100 PY in HIV-exposed infants (10%, 17/170) versus 1.7/100 PY in HIV-unexposed infants (3.3%, 5/152) [hazard ratio (HR): 3.1 (95% CI: 1.2-8.5)]. More TST conversions occurred in the first versus second year of life [5.8 vs. 2.0/100 PY; HR: 2.9 (95% CI: 1.0-10.1)]. Infant TST-positivity was associated with maternal TST-positivity [HR: 2.9 (95% CI: 1.1-7.4)], but not QFT-Plus-positivity. Among HIV-exposed children, Mtb infection incidence was similar regardless of maternal IPT.

CONCLUSIONS

Mtb infection incidence (by TST) by 24 months of age was ~3-fold higher among HIV-exposed children, despite high maternal IPT uptake. Overall, more TST conversions occurred in the first 12 months compared to 12-24 months of age, similar in both HIV-exposed and HIV-unexposed children.

Impact of Human Immunodeficiency Virus and Peripartum Period on Mycobacterium tuberculosis Infection Detection

BACKGROUND

Pregnancy and human immunodeficiency virus (HIV) may influence tuberculosis infection detection using interferon (IFN)-γ release assay (QFT-Plus; Qiagen) and tuberculin skin test (TST).

METHODS

Participants in Western Kenya underwent QFT-Plus and TST in pregnancy, 6 weeks postpartum (6wkPP) and 12 months postpartum (12moPP).

RESULTS

400 participants (200 with HIV [WHIV], 200 HIV-negative) enrolled during pregnancy (median 28 weeks' gestation [interquartile range, 24-30]). QFT-Plus positivity prevalence was higher than TST in pregnancy (32.5% vs 11.6%) and through 12moPP (6wkPP, 30.9% for QFT-Plus vs 18.0% for TST; 12moPP, 29.5% vs 17.1%; all P < .001), driven primarily by QFT-Plus-positive/TST-negative discordance among HIV-negative women. Tuberculosis infection test conversion incidence was 28.4/100 person-years (PY) and higher in WHIV than HIV-negative women (35.5 vs 20.9/100 PY; hazard ratio, 1.73 [95% confidence interval, 1.04-2.88]), mostly owing to early postpartum TST conversion among WHIV. Among QFT-Plus-positive participants in pregnancy, Mycobacterium tuberculosis  (Mtb)-specific IFN-γ responses were dynamic through 12moPP and lower among WHIV than HIV-negative women with tuberculosis infection at all time points.

CONCLUSIONS

QFT-Plus had higher diagnostic yield than TST in peripartum women. Peripartum QFT-Plus positivity was stable and less influenced by HIV than TST. Mtb-specific IFN-γ responses were dynamic and lower among WHIV. Tuberculosis infection test conversion incidence was high between pregnancy and early postpartum, potentially owing to postpartum immune recovery.

Prevalence and predictors of tuberculosis infection among people living with HIV in a high tuberculosis burden context

BACKGROUND

Tuberculosis (TB) disease is the leading cause of mortality among people living with HIV (PLHIV). Interferon-gamma release assays (IGRAs) are approved for TB infection ascertainment. However, current IGRA data on the prevalence of TB infection in the context of near-universal access to antiretroviral therapy (ART) and TB preventive therapy (TPT) are lacking. We estimated the prevalence and determinants of TB infection among PLHIV within a high TB and HIV burden context.

METHODS

This cross-sectional study included data from adult PLHIV age ≥18 years in whom QuantiFERON-TB Gold Plus (QFT-Plus) assay, an IGRA, was performed. TB infection was defined as a positive or indeterminate QFT-Plus test. Participants with TB and those who had previously used TPT were excluded. Regression analysis was performed to identify independent predictors of TB infection.

RESULTS

Of 121 PLHIV with QFT-Plus test results, females were 74.4% (90/121), and the mean age was 38.4 (SD 10.8) years. Overall, 47.9% (58/121) were classified as TB infection (QFT-Plus test positive and indeterminate results were 39.7% (48/121) and 8.3% (10/121), respectively). Being obese/overweight (body mass index ≥25 kg/m²; p=0.013, adjusted OR (aOR) 2.90, 95% CI 1.25 to 6.74) and ART usage for >3 years (p=0.013, aOR 3.99, 95% CI 1.55 to 10.28) were independently associated with TB infection.

CONCLUSION

There was a high TB infection prevalence among PLHIV. A longer period of ART and obesity were independently associated with TB infection. The relationship between obesity/overweight and TB infection may be related to ART use and immune reconstitution and requires further investigation. Given the known benefit of test-directed TPT among PLHIV never exposed to TPT, its clinical and cost implications for low and middle-income countries should be explored further.

Tuberculosis Infection in Pregnant People: Current Practices and Research Priorities

Women are significantly more likely to develop tuberculosis (TB) disease within the first 90 days after pregnancy than any other time in their lives. Whether pregnancy increases risk of progression from TB infection (TBI) to TB disease is unknown and is an active area of investigation. In this review, we discuss the epidemiology of TB and TBI in pregnancy, TBI diagnostics, and prevalence in pregnancy. We also review TBI treatment and highlight research priorities, such as short-course TB prevention regimens, drug-resistant TB prevention, and additional considerations for safety, tolerability, and pharmacokinetics that are unique to pregnant and postpartum people.