Longitudinal Mycobacterium tuberculosis specific interferon-γ responses in Ethiopian HIV-negative women during pregnancy and post-partum

Pregnancy Outcomes in Women Screened for Tuberculosis Infection in Swedish Antenatal Care

BACKGROUND

Tuberculosis (TB) disease has been associated with pregnancy complications. However, the potential impact of TB infection (TBI) on pregnancy outcome is unknown. To investigate this, we conducted a register-based study in immigrant women screened with QuantiFERON assays for TBI in antenatal care in Sweden.

METHODS

Women with history of immigration from TB-endemic countries were eligible for inclusion if national identification numbers and available QuantiFERON results obtained during pregnancy from 2014 to 2018 were available. QuantiFERON results were linked to data on maternal characteristics and pregnancy outcomes from the national Pregnancy and Patient Registers. TBI was defined as nil-corrected QuantiFERON result ≥0.35 IU/mL, in the absence of TB disease. Pregnancies in women with TB disease or human immunodeficiency virus were excluded, as were multiplex pregnancies, pregnancies resulting in miscarriage, and pregnancies occurring >10 years after immigration. Odds of defined adverse pregnancy outcomes were compared by maternal TBI status using mixed effects logistic regression with adjustment for maternal age and region of origin.

RESULTS

In total, 7408 women with 12 443 pregnancies were included. In multivariable analysis, stillbirth (adjusted odds ratio [AOR], 1.90; 95% confidence interval [CI], 1.13-3.21; P = .016), severe preeclampsia (AOR, 1.62; 95% CI, 1.03-2.56; P = .036), low birthweight (<2500 g; AOR, 1.38; 95% CI, 1.01-1.88; P = .041), and emergency cesarean section (AOR, 1.28; 95% CI, 1.02-1.63; P = .033) were significantly associated with TBI.

CONCLUSIONS

Among immigrant women seeking antenatal care in Sweden, TBI was independently associated with adverse pregnancy outcomes. Further studies are needed to corroborate these findings and to explore mechanisms involved.

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.

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.

Dynamics of Mycobacterium tuberculosis-Specific and Nonspecific Immune Responses in Women with Tuberculosis Infection during Pregnancy

The immune control of tuberculosis (TB) infection could be influenced by pregnancy. To elucidate this, we longitudinally characterized Mycobacterium tuberculosis (Mtb)-specific and nonspecific immune responses in women during pregnancy and postpartum. HIV-uninfected women without past or current active TB, and with blood samples available from the 1st/2nd trimester, 3rd trimester, and 9 months postpartum, were identified at Ethiopian antenatal care clinics. Twenty-two TB+ women and 10 TB- women, defined according to Mtb-stimulated interferon-γ levels (≥0.35 and <0.20 IU/mL, respectively, in the Quantiferon-TB Gold-Plus assay), were included in the study. Longitudinal dynamics of six cytokines (IL-1ra, IL-2, IP-10, MCP-2, MCP-3, and TGF-β1) were analyzed in supernatants from Mtb-stimulated and unstimulated whole blood. In TB+ women, Mtb-specific expression of IL-2 and IP-10 was higher at 3rd compared to 1st/2nd trimester (median 139 pg/mL versus 62 pg/mL, P = 0.006; 4,999 pg/mL versus 2,310 pg/mL, P = 0.031, respectively), whereas level of Mtb-triggered TGF-β1 was lower at 3rd compared to 1st/2nd trimester (-6.8 ng/mL versus 2.3 ng/mL, P = 0.020). Unstimulated IL-2, IP-10, and MCP-2 levels were increased postpartum, compared with those noted during pregnancy, in TB+ women. Additionally, postpartum levels of proinflammatory cytokines in unstimulated blood were higher in TB+ women, than in TB- women. None of the women developed active TB during follow-up. Taken together, dynamic changes of Mtb-specific cytokine expression revealed during the 3rd trimester in TB+ women indicate increased Mtb-antigen stimulation at later stages of pregnancy. This could reflect elevated bacterial activity, albeit without transition to active TB, during pregnancy. IMPORTANCE Tuberculosis (TB) is globally one of the most common causes of death, and a quarter of the world's population is estimated to have TB infection. The risk of active TB is increased in connection to pregnancy, a phenomenon that could be due to physiological immune changes. Here, we studied the effect of pregnancy on immune responses triggered in HIV-uninfected women with TB infection, by analyzing blood samples obtained longitudinally during pregnancy and after childbirth. We found that the dynamics of Mtb-specific and nonspecific immune responses changed during pregnancy, especially in later stages of pregnancy, although none of the women followed in this study developed active TB. This suggests that incipient TB, with elevated bacterial activity, occurs during pregnancy, but progression of infection appears to be counteracted by Mtb-specific immune responses. Thus, this study sheds light on immune control of TB during pregnancy, which could be of importance for future intervention strategies.

Longitudinal Variations of M. tuberculosis-Induced IFN-γ Responses in HIV-Negative Pregnant Women Exposed to Tuberculosis

Introduction

Pregnancy triggers an alteration of the immune functions and increases the risk of developing the active tuberculosis (TB) symptoms in exposed women. The effect of pregnancy on the Mycobacterium tuberculosis-specific immune responses used for most of the TB immunodiagnostic assays is not well documented. Here we investigated the changes in the M. tuberculosis-specific IFN-γ production in age-matched pregnant and non-pregnant women according to their TB exposition status.

Methods

We conducted a prospective cohort study on HIV-seronegative pregnant and non-pregnant women with compatible pulmonary TB symptoms addressed to TB healthcare facilities in Antananarivo, Madagascar. Active pulmonary TB was bacteriologically assessed with culture from sputum samples. Clinical data and blood samples were collected at inclusion and after 6 months of follow-up for each individual included. Whole blood samples were stimulated with QuantiFERON TB-Gold Plus (QFT-P) assay antigens. Plasma IFN-γ concentrations were then assessed by ELISA.

Results

A total of 284 women were investigated for the study including 209 pregnant women without confirmed TB (pNTB), 24 pregnant women with bacteriologically confirmed active TB (pATB), 16 non-pregnant women with active TB (ATB), and 35 non-pregnant healthy donors (HC). At inclusion, IFN-γ responses are lower in the pregnant women compared to their age-matched non-pregnant counterparts and independently of their TB status. Among the pregnant women, higher concentrations of M. tuberculosis-specific IFN-γ were observed in those exposed to TB, but with a lower magnitude in the active TB compared to the latently infected pregnant women (p < 0.05 with TB1 and p < 0.01 with TB2). After 6 months of follow-up, the M. tuberculosis-specific IFN-γ responses return to their baseline concentrations except for the pregnant women treated for TB for which none of the QFT-P positive reversed to negative (0%, 0/10) at the end of their TB treatment.

Conclusion

These results support the concept of specific immune priorities characterized by a concomitant reduction in inflammatory immunity during pregnancy and corroborate the important role of activating the M. tuberculosis-specific immune responses to control the infection when the pregnant women are exposed to the pathogen.

Diagnostic Value of Interferon-Gamma Release Assays for Tuberculosis in the Immunocompromised Population

Interferon-gamma release assays (IGRAs) are widely used in the diagnosis of Mycobacterium tuberculosis (M. tuberculosis) infection by detecting interferon-γ released by previously sensitized T-cells in-vitro. Currently, there are two assays based on either enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISPOT) technology, with several generations of products available. The diagnostic value of IGRAs in the immunocompromised population is significantly different from that in the immunocompetent population because their results are strongly affected by the host immune function. Both physiological and pathological factors can lead to an immunocompromised situation. We summarized the diagnostic value and clinical recommendations of IGRAs for different immunocompromised populations, including peoplewith physiological factors (pregnant and puerperal women, children, and older people), as well as people with pathological factors (solid organ transplantation recipients, combination with human immunodeficiency virus infection, diabetes mellitus, end-stage renal disease, end-stage liver disease, and chronic immune-mediated inflammatory diseases). Though the performance of IGRAs is not perfect and often requires a combination with other diagnostic strategies, it still has some value in the immunocompromised population. Hopefully, the newly developed IGRAs could better target this population.