Do Childhood Infections Contribute to Adult Cardiometabolic Diseases?

Neonatal Subcutaneous BCG Vaccination Decreases Atherosclerotic Plaque Number and Plaque Macrophage Content in ApoE-/- Mice

Bacille-Calmette Guérin (BCG) modulates atherosclerosis development in experimental animals, but it remains unclear whether neonatal BCG vaccination is pro- or anti-atherogenic. Many animal models differ fundamentally from BCG administration to human infants in terms of age, vaccine preparation, dosing schedule, and route of administration. We aimed to elucidate the effect of neonatal subcutaneous BCG vaccination—analogous to human BCG vaccination—on atherosclerosis development in ApoE−/− mice. At 2 days of age, a total of 40 ApoE−/− mice received either a weight-equivalent human dose of BCG, or saline, subcutaneously. From 4 weeks onwards, the mice were fed a Western-type diet containing 22% fat. At 16 weeks of age, mice were sacrificed for the assessment of atherosclerosis. Body weight, plasma lipids, atherosclerosis lesion size and collagen content were similar in both groups. Atherosclerosis lesion number was lower in mice that received BCG. Macrophage content was 20% lower in the BCG-vaccinated mice (p < 0.05), whereas plaque lipid content was increased by 25% (p < 0.01). In conclusion, neonatal BCG vaccination reduces atherosclerosis plaque number and macrophage content but increases lipid content in a murine model of atherosclerosis. Human epidemiological and mechanistic studies are warranted to investigate whether neonatal BCG vaccination is potentially atheroprotective.

Early life infection and proinflammatory, atherogenic metabolomic and lipidomic profiles in infancy: a population-based cohort study

Background:

The risk of adult onset cardiovascular and metabolic (cardiometabolic) disease accrues from early life. Infection is ubiquitous in infancy and induces inflammation, a key cardiometabolic risk factor, but the relationship between infection, inflammation, and metabolic profiles in early childhood remains unexplored. We investigated relationships between infection and plasma metabolomic and lipidomic profiles at age 6 and 12 months, and mediation of these associations by inflammation.

Methods:

Matched infection, metabolomics, and lipidomics data were generated from 555 infants in a pre-birth longitudinal cohort. Infection data from birth to 12 months were parent-reported (total infections at age 1, 3, 6, 9, and 12 months), inflammation markers (high-sensitivity C-reactive protein [hsCRP]; glycoprotein acetyls [GlycA]) were quantified at 12 months. Metabolic profiles were 12-month plasma nuclear magnetic resonance metabolomics (228 metabolites) and liquid chromatography/mass spectrometry lipidomics (776 lipids). Associations were evaluated with multivariable linear regression models. In secondary analyses, corresponding inflammation and metabolic data from birth (serum) and 6-month (plasma) time points were used.

Results:

At 12 months, more frequent infant infections were associated with adverse metabolomic (elevated inflammation markers, triglycerides and phenylalanine, and lower high-density lipoprotein [HDL] cholesterol and apolipoprotein A1) and lipidomic profiles (elevated phosphatidylethanolamines and lower trihexosylceramides, dehydrocholesteryl esters, and plasmalogens). Similar, more marked, profiles were observed with higher GlycA, but not hsCRP. GlycA mediated a substantial proportion of the relationship between infection and metabolome/lipidome, with hsCRP generally mediating a lower proportion. Analogous relationships were observed between infection and 6-month inflammation, HDL cholesterol, and apolipoprotein A1.

Conclusions:

Infants with a greater infection burden in the first year of life had proinflammatory and proatherogenic plasma metabolomic/lipidomic profiles at 12 months of age that in adults are indicative of heightened risk of cardiovascular disease, obesity, and type 2 diabetes. These findings suggest potentially modifiable pathways linking early life infection and inflammation with subsequent cardiometabolic risk.

Funding:

The establishment work and infrastructure for the BIS was provided by the Murdoch Children’s Research Institute (MCRI), Deakin University, and Barwon Health. Subsequent funding was secured from National Health and Medical Research Council of Australia (NHMRC), The Shepherd Foundation, The Jack Brockhoff Foundation, the Scobie & Claire McKinnon Trust, the Shane O’Brien Memorial Asthma Foundation, the Our Women’s Our Children’s Fund Raising Committee Barwon Health, the Rotary Club of Geelong, the Minderoo Foundation, the Ilhan Food Allergy Foundation, GMHBA, Vanguard Investments Australia Ltd, and the Percy Baxter Charitable Trust, Perpetual Trustees. In-kind support was provided by the Cotton On Foundation and CreativeForce. The study sponsors were not involved in the collection, analysis, and interpretation of data; writing of the report; or the decision to submit the report for publication. Research at MCRI is supported by the Victorian Government’s Operational Infrastructure Support Program. This work was also supported by NHMRC Senior Research Fellowships to ALP (1008396); DB (1064629); and RS (1045161) , NHMRC Investigator Grants to ALP (1110200) and DB (1175744), NHMRC-A*STAR project grant (1149047). TM is supported by an MCRI ECR Fellowship. SB is supported by the Dutch Research Council (452173113).

Innate Immune Activation and Circulating Inflammatory Markers in Preschool Children

Early childhood is characterised by repeated infectious exposures that result in inflammatory responses by the innate immune system. In addition, this inflammatory response to infection is thought to contribute to the epidemiological evidence linking childhood infection and adult non-communicable diseases. Consequently, the relationship between innate immune responses and inflammation during early life may inform prevention of NCDs later in life. In adults, non-genetic host factors such as age, sex, and obesity, strongly impact cytokine production and circulating mediators, but data in children are lacking. Here, we assessed cytokine responses and inflammatory markers in a population of healthy preschool children (mean age 4.2 years). We studied associations between cytokines, plasma inflammatory markers and non-genetic host factors, such as sex, age, adiposity, season, and immune cell composition. Similar to adults, boys had a higher inflammatory response than girls, with IL-12p70 and IL-10 upregulated following TLR stimulation. Adiposity and winter season were associated with increased circulating inflammatory markers but not cytokine production. The inflammatory markers GlycA and hsCRP were positively associated with production of a number of cytokines and may therefore reflect innate immune function and inflammatory potential. This dataset will be informative for future prospective studies relating immune parameters to preclinical childhood NCD phenotypes.

Preterm birth and sustained inflammation: consequences for the neonate

Almost half of all preterm births are caused or triggered by an inflammatory process at the feto-maternal interface resulting in preterm labor or rupture of membranes with or without chorioamnionitis (“first inflammatory hit”). Preterm babies have highly vulnerable body surfaces and immature organ systems. They are postnatally confronted with a drastically altered antigen exposure including hospital-specific microbes, artificial devices, drugs, nutritional antigens, and hypoxia or hyperoxia (“second inflammatory hit”). This is of particular importance to extremely preterm infants born before 28 weeks, as they have not experienced important “third-trimester” adaptation processes to tolerate maternal and self-antigens. Instead of a balanced adaptation to extrauterine life, the delicate co-regulation between immune defense mechanisms and immunosuppression (tolerance) to allow microbiome establishment is therefore often disturbed. Hence, preterm infants are predisposed to sepsis but also to several injurious conditions that can contribute to the onset or perpetuation of sustained inflammation (SI). This is a continuing challenge to clinicians involved in the care of preterm infants, as SI is regarded as a crucial mediator for mortality and the development of morbidities in preterm infants. This review will outline the (i) role of inflammation for short-term consequences of preterm birth and (ii) the effect of SI on organ development and long-term outcome.

Increased Carotid Intima-Media Thickness in Children with a History of Dengue Hemorrhagic Fever

We assessed carotid intima-media thickness (cIMT) and arterial stiffness in 28 children and adolescents with previous dengue hemorrhagic fever (DHF) (mean interval between DHF and cardiovascular assessment, 8.4 years), and 34 controls in a low-resource setting. Participants with previous DHF had an adjusted increased cIMT of 42.6 µm (95% confidence interval [CI]: 10.0-75.3, P = 0.01), and 61.7 µm (95% CI: 21.5-102.0, P < 0.01) in a subgroup analysis on dengue shock syndrome. There were no differences in arterial stiffness. In this first exploratory study, children and adolescents with a history of DHF had an increased cIMT, which may be modulated by dengue severity.

Association between human immunodeficiency virus infection and arterial stiffness in children

Background Human immunodeficiency virus infection (HIV) is associated with increased cardiovascular risk and adverse cardiovascular outcome in adults. Early recognition of changes in vascular properties might prove essential in cardiovascular prevention in HIV-infected patients. We investigated the relations between HIV infection and arterial stiffness in children. Methods This cross-sectional study included 51 HIV-infected and 52 healthy children (age 3.2-14.5 years, 49 males). All infected children had acquired HIV by vertical transmission and were receiving antiretroviral therapy at time of assessment. Arterial stiffness was measured by pulse wave velocity and aortic augmentation index, using the Arteriograph system (Tensiomed Kft, Budapest, Hungary). We applied multivariable general linear modeling to evaluate the relationship between HIV infection and arterial stiffness with further adjustment for confounders and possible intermediary variables. Findings represent mean group differences with 95% confidence intervals and p values. Results Aortic augmentation index was higher by 9.0% (5.6-12.5, p < 0.001) in HIV-infected than in healthy children. Adjustment for blood pressure, protease inhibitor use, biomarkers for level of inflammation, lipid- and glucose-metabolism, as possible intermediary variables, did not appreciably alter the results. There were no significant differences in pulse wave velocity between HIV-infected and healthy children (mean difference 0.28 m/s, -0.14-0.69, p = 0.19). Conclusion HIV-infected children have an increased aortic augmentation index, compared to healthy children. Early cardiovascular assessment may be important in targeted prevention for HIV-infected children.

Inflammation, lipids and aortic intima-media thickness in newborns following chorioamnionitis

AIM

This study investigated whether chorioamnionitis was associated with increased inflammation, dyslipidaemia and adverse cardiovascular phenotypes in the immediate postnatal period.

METHODS

This prospective case-control study included preterm infants (30(+0) -35(+6) weeks gestational age, GA) whose mothers did not have pregnancy-related conditions that may influence outcomes. Chorioamnionitis was diagnosed by placental histology, and infants were divided retrospectively into cases (chorioamnionitis-exposed) and controls (unexposed). Serum high-sensitivity C-reactive protein (hsCRP), lipid profile, far-wall abdominal aortic intima-media thickness (aIMT) and blood pressure (BP) were measured in the first week of life.

RESULTS

There were 20 (16 male, mean GA 32.4 weeks) cases and 31 (12 male, mean GA 32.6 weeks) controls. Histological chorioamnionitis was associated with a significant increase in hsCRP and a non-significant trend towards an adverse lipid profile. There was no evidence of differences in aIMT or BP.

CONCLUSION

Preterm infants exposed to chorioamnionitis have greater postnatal inflammation. There were no early postnatal differences in aIMT or BP. The inflammatory stimulus of chorioamnionitis late in gestation may be of insufficient intensity and duration to result in immediate postnatal alterations to arterial structure. Cardiovascular follow-up of infants exposed to chorioamnionitis may identify differential risk trajectories and subsequent inflammatory responses.

Infections in early life and premature acute coronary syndrome: A case-control study

BACKGROUND

Infections in young children may affect the vasculature and initiate early atherosclerosis. Whether infections experienced in childhood play a part in adult clinical cardiovascular disease remains unclear. We investigated the association between infections in early life and the occurrence of premature coronary heart disease.

METHODS

We conducted a population-based case-control study of 153 patients with a first acute coronary syndrome before the age of 56 years and 153 age- and sex-matched controls. Any history of severe infections in childhood and adolescence was obtained, together with clinical and laboratory measurements and other cardiovascular risk factors. We developed an infection score for the overall burden of early life infections. Conditional logistic regression was used to assess the associations.

RESULTS

Infections experienced in early life increased the risk of acquiring acute coronary syndrome at a young age with an odds ratio (OR) of 2.67 (95% confidence interval (CI) 1.47-4.83, p = 0.001). After adjustments for traditional risk factors, lifestyle, dietary patterns, socio-economic status and parental history of cardiovascular events, these associations remained significant and changed only slightly. There was an indication for an interaction between infections in early life and current cardiovascular risk (Framingham Risk Score (FRS); p-interaction = 0.052). Within participants with a low FRS (<10%), the OR of early life infection for acute coronary syndrome was 1.49 (95% CI 0.72-3.08, p = 0.283); within participants with an intermediate FRS (10-20%), the OR was 4.35 (95% CI 1.60-11.84, p = 0.004); and within participants with a high FRS (>20%), the OR 10.00 (95% CI 1.21-82.51, p = 0.032).

CONCLUSION

Infections in early life may partly explain premature coronary heart disease in adulthood and may potentiate traditional cardiovascular risk factor effects.