Tuberculosis Potential Risk Factor for Asthma in Offspring

Asthma and respiratory symptoms in pediatric patients may be rooted in the occurrence of tuberculosis (TB) in their parents, according to a recent study, with investigators postulating that the infection’s immunological impact may be to blame for the specific asthma phenotype.

“Given the profound impact of tuberculosis on immunity,” the study authors wrote in Frontiers in Allergy, “we hypothesize that parental TB might impact respiratory health in their offspring.” They used data from the third follow-up of the Respiratory Health in Northern Europe (RHINE) study, itself a follow-up of the postal survey administered for the European Community Respiratory Health Survey; questionnaires were used to gather these data, which encompass asthma status, asthma-like symptoms, other respiratory symptoms, and parental TB and asthma status.

The patient cohort had 8323 participants; their median age was 62 (range, 46-79) years and 53% were female. Mean (SD) overall body mass index was 26.8 (4.7) kg/m². More patients reported their mothers to have TB (3.4%) compared with their fathers (2.7%), and 0.4% said that both parents had TB.

Overall, 20.9% reported they currently had asthma or experienced 3 or more asthma symptoms; 14.9% had an asthma symptom score of 3 or higher based on affirmative answers to 5 questions (1 point each), 13.9% have or ever had asthma, 11.9 currently has just asthma, 11.2% are currently taking asthma medication, and 4.5% had an asthma attack in the past year.

Fifty-one percent reported that at least 1 parent had a smoking history and 10.9% that at least 1 parent had a history of asthma.

In addition, a history of TB in both parents was linked to a 30% rate of currently or ever having asthma among the children of those parents compared with a 13% asthma rate among study participants not reporting TB in either parent. Parental TB was also linked with greater chances of several asthma and respiratory symptoms, and the top 5 were the following:

• Current asthma and/or at least 3 asthma symptoms and no nasal allergy: 64% (odds ratio [OR], 1.64; 95% CI, 1.27-2.12; P < .000)
• Wheezing: 44% (OR, 1.44; 1.18-1.6; P = .001)
• Current asthma: 38% (OR, 1.38; 95% CI, 1.08-1.76; P = .019)
• Has 3 or more asthma symptoms: 34% (OR, 1.34; 95% CI, 1.07-1.68; P = .017)
• Current asthma and/or at least 3 asthma symptoms: 32% (OR, 1.32; 95% CI, 1.07-1.61; P = .015)

No significant association was seen between parental TB and nonallergic asthma.

An additional analysis that stratified the risk of parental TB and offspring asthma by offspring’s sex showed higher odds of offspring having asthma, reporting 3 or more asthma symptoms, and both if female vs male:

• Current asthma: 34% (adjusted OR [aOR], 1.34; 95% CI, 0.99-1.80; P = .056) vs 25% (aOR, 1.25; 95% CI, .081-1.94; P = .306)
• Reports 3 or more asthma symptoms: 35% (aOR, 1.35; 95% CI, 1.02-1.77; P = .014) vs 13% (aOR, 1.13; 95% CI, 0.75-1.71; P = .546)
• Current asthma and reports 3 or more asthma symptoms: 33% (aOR, 1.03-1.70; P = .026) vs 13% (aOR, 1.13; 95% CI, 0.79-1.61; P = .470)

The study investigators noted that both maternal and paternal lines reported similar associations between parental TB and greater odds of asthma and respiratory symptoms in offspring, as well that their findings “support the general hypothesis that parental exposures before conception could influence future generations.

The latter especially is a strength because it adds to a growing evidence base showing potential links between preconception parental exposure to environmental factors and offspring disease phenotype. Limitations include potential asthma misdiagnoses and having offspring report parental TB via a questionnaire.

“We speculate that the profound immunologic response to TB in parents might lead to epigenetic modification of germline cells and thereby influencing offspring phenotype,” the study authors concluded. “Our hypothesis-generating results should be investigated further, both in epidemiological and mechanistic studies.”

Reference

Gyawali S, López-Cervantes JP, Johannessen A, et al. Maternal and paternal tuberculosis is associated with increased asthma and respiratory symptoms in their offspring: a study from Northern Europe. Front Allergy. Published online June 8, 2023. doi:10.3389/falgy.2023.1193141