Infant cortisol stress-response is associated with thymic function and vaccine response

The effect of stress on the antibody response after vaccination in children aged 0-18 years: A systematic review

Stress has been associated with less effective vaccine responses in adults. This review aims to investigate the evidence for a similar association in children. A systematic review search was conducted in January 2021 in three databases: Medline, Embase and PsycInfo. An updated search of the Medline database was systematically conducted until the most recent update on September 25th, 2023, to ensure the inclusion of the most current research available. Keywords related to stress, vaccines and children were used, and a total of 7263 (+1528) studies were screened by two independent investigators. Six studies met the inclusion criteria for data extraction and analysis. For quality assessment of the studies, the risk of bias in non-randomized studies-of interventions (ROBINS-I) tool was applied. Most of the studies suggest a negative role of stress on vaccine responses. However, the scarcity of studies, lack of confirmatory studies, risk of bias and heterogeneity according to age, type of vaccine, measures of stress and vaccine responses prevent a clear conclusion. Future studies should emphasize the use of as strict study designs as possible, including well-defined stress metrics and thorough examination of both pre- and post-vaccination responses. Systematic review registration: Prospero CRD42021230490.

A case of vitiligo after COVID-19 vaccination: a possible role of thymic dysfunction

During the coronavirus disease 2019 (COVID-19) pandemic, vaccines help control the spread of infection. To date, 47 vaccines have been approved, with another 227 candidates in various stages of development. In the short period of time since the beginning of their use, evidence has begun to emerge of complications following vaccination in the form of the development or exacerbation of a number of pathological conditions (Block et al., 2022; Haseeb et al., 2022). For example, a population-based study in France identified 1612 cases of myocarditis and 1613 cases of pericarditis requiring hospital treatment within five months of vaccination (le Vu et al., 2022).

Effect of Combined Thoracic Paravertebral Block and General Anesthesia vs General Anesthesia Alone on Postoperative Stress and Pain in Patients Undergoing Laparoscopic Radical Nephrectomy

Background

This single-center study compared the effect of combined thoracic paravertebral block (TPVB) and general anesthesia vs general anesthesia alone on postoperative stress and pain in patients undergoing laparoscopic radical nephrectomy.

Material/Methods

Patients undergoing laparoscopic radical nephrectomy were selected and randomized into a study group given TPVB combined with general anesthesia (n=43) and a reference group (n=43) given general anesthesia. The perioperative clinical indicators, blood pressure, pulse rate, visual analog scale (VAS) score, and adverse reactions were compared.

Results

Perioperative clinical indicators of the study group (other than operation duration) were superior to those of the reference group (P<0.05). At 90 min in the operation, systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse rate were lower than before anesthesia (t=7.691, 10.017, and 7.728, P<0.05). SBP, DBP, and pulse rate at 90 minutes during operation were significantly lower in the study group than in the reference group (t=7.582, 8.754, and 6.682, P<0.01). The study group had lower VAS scores both during activity and at rest 48 h after the operation than in the reference group (t=5.171 and 6.025, P<0.001). The total incidence of adverse reactions in the study group was lower than in the reference group (χ²=5.018, P=0.024).

Conclusions

The findings from this study from a single center showed that TPVB combined with general anesthesia for patients undergoing laparoscopic radical nephrectomy significantly reduced postoperative pain and stress.

Dynamics of thymus function and T cell receptor repertoire breadth in health and disease

T cell recognition of unknown antigens relies on the tremendous diversity of the T cell receptor (TCR) repertoire; generation of which can only occur in the thymus. TCR repertoire breadth is thus critical for not only coordinating the adaptive response against pathogens but also for mounting a response against malignancies. However, thymic function is exquisitely sensitive to negative stimuli, which can come in the form of acute insult, such as that caused by stress, infection, or common cancer therapies; or chronic damage such as the progressive decline in thymic function with age. Whether it be prolonged T cell deficiency after hematopoietic cell transplantation (HCT) or constriction in the breadth of the peripheral TCR repertoire with age; these insults result in poor adaptive immune responses. In this review, we will discuss the importance of thymic function for generation of the TCR repertoire and how acute and chronic thymic damage influences immune health. We will also discuss methods that are used to measure thymic function in patients and strategies that have been developed to boost thymic function.

High-Dose Neonatal Vitamin A Supplementation Transiently Decreases Thymic Function in Early Infancy

BACKGROUND

Vitamin A deficiency (VAD) impairs T-cell-mediated immunity. In regions where VAD is prevalent, vitamin A supplementation (VAS) reduces child mortality, perhaps by improving immune function.

OBJECTIVE

Our objective was to determine if neonatal VAS would improve thymic function in Bangladeshi infants, and to determine if such effects differed by sex or nutritional status (i.e., birth weight above/below the median).

METHODS

Three hundred and six infants were randomly assigned to 50,000 IU vitamin A (VA) or placebo (PL) within 48 h of birth. Primary outcomes were measured at multiple ages and included 1) thymic index (TI) at 1, 6, 10, and 15 wk; 2) T-cell receptor excision circles (TREC), an index of thymic output of naïve T cells; and 3) total/naïve T cells in peripheral blood at 6 wk, 15 wk, and 2 y. A mixed linear model for repeated measures was used to assess group differences at each age and identify interactions with sex and birth weight.

RESULTS

VAS did not significantly (P = 0.21) affect TI overall (i.e., at all ages) but decreased TI by 7.8% (P = 0.029) at 6 wk: adjusted TI means for the PL and VA groups at 1, 6, 10, and 15 wk were 4.09 compared with 3.80 cm2, 7.78 compared with 7.18 cm2, 8.11 compared with 7.84 cm2, and 7.91 compared with 7.97 cm2, respectively. VAS did not significantly (P = 0.25) affect TREC overall but decreased TREC by 19% (P = 0.029) at 15 wk: adjusted TREC means for the PL and VA groups at 6 wk, 15 wk, and 2 y were 13.6 compared with 16.1 copies/pg DNA, 19.4 compared with 15.7 copies/pg DNA, and 11.8 compared with 10.0 copies/pg DNA, respectively. VAS did not significantly affect overall total (P = 0.10) or naïve (P = 0.092) T cells: adjusted naïve T-cell means for the PL and VA groups at 6 wk, 15 wk, and 2 y were 3259 compared with 3109 cells/µL, 3771 compared with 3487 cells/µL, and 1976 compared with 1898 cells/µL, respectively.

CONCLUSION

In contrast to our hypothesis, VAS decreased thymic function early in infancy but health effects are presumably negligible owing to the transience and small magnitude of this effect. This trial was registered at clinicaltrials.gov as NCT01583972 and NCT02027610.

Factors associated with diarrhea and acute respiratory infection in children under two years of age in rural Bangladesh

Background

Diarrhea and acute respiratory infection (ARI) are major causes of child mortality. We aimed to identify risk factors associated with diarrhea and ARI among children under 2 years of age in rural northern Bangladesh.

Method

We collected information on diarrhea and ARI in the previous 14 days and the previous 6 months at 6, 12, 18 and 24 months of age as part of a longitudinal, cluster randomized effectiveness trial, the Rang-Din Nutrition Study which enrolled 4011 pregnant women at ≤20 gestational weeks. Women and their children were followed up until 2 years postpartum. Information on household socioeconomic status, type of toilet, garbage disposal system, food insecurity, number of under-five children in the household, type of family, maternal characteristics and child characteristics was collected at baseline and/or at 6, 12, 18 and 24 months postpartum. Data on newborn health and feeding behaviors were collected within 72 h of delivery. Associations between potential risk factors and morbidity prevalence outcomes were assessed using logistic regression controlling for potential confounders.

Results

Out of 3664 live born children, we collected information from ~ 3350 children at 6, 12, 18 and 24 months of age. Diarrhea in the previous 14 days, and in the previous 6 months, was associated with maternal depression score and food insecurity; diarrhea in the previous 6 months was also associated with family type (nuclear vs. joint). ARI in the previous 14 days was associated with maternal depression score, type of toilet and garbage disposal, household food insecurity and sex. Cough or nasal discharge in the past 6 months was associated with maternal depression score, type of toilet and garbage disposal, household food insecurity, sex and perceived overall physical condition of the infant after birth.

Conclusion

Maternal depression and food insecurity appear to be important risk factors for diarrhea and respiratory infection among children under 2 years of age in this setting. These findings suggest that policies and programs that include strategies to address maternal mental health and household food insecurity may contribute to improved child health.

Trial registration

The trial was registered with the US National Institutes of Health at ClinicalTrials.gov, # NCT01715038, with registration completed October 26, 2012. 

Bifidobacterium Abundance in Early Infancy and Vaccine Response at 2 Years of Age

BACKGROUND

The intestinal microbiome in early infancy affects immunologic development and thus may affect vaccine memory, though few prospective studies have examined such associations. We examined the association of Bifidobacterium levels in early infancy with memory responses to early vaccination measured at 2 years of age.

METHODS

In this prospective observational study, we examined the association of Bifidobacterium abundance in the stool of healthy infants at 6 to 15 weeks of age, near the time of vaccination, with T-cell and antibody responses measured at 6 weeks, 15 weeks, and 2 years of age. Infants were vaccinated with Bacillus Calmette-Guérin (BCG) (at birth), oral polio virus (at birth and at 6, 10, and 14 weeks), tetanus toxoid (TT) (at 6, 10, and 14 weeks), and hepatitis B virus (at 6, 10, and 14 weeks). Fecal Bifidobacterium was measured at 6, 11, and 15 weeks. Bifidobacterium species and subspecies were measured at 6 weeks.

RESULTS

Mean Bifidobacterium abundance in early infancy was positively associated with the CD4 T-cell responses to BCG, TT, and hepatitis B virus at 15 weeks, with CD4 responses to BCG and TT at 2 years, and with plasma TT-specific immunoglobulin G and stool polio-specific immunoglobulin A at 2 years. Similar associations were seen for the predominant subspecies, Bifidobacterium longum subspecies infantis.

CONCLUSIONS

Bifidobacterium abundance in early infancy may increase protective efficacy of vaccines by enhancing immunologic memory. This hypothesis could be tested in clinical trials of interventions to optimize Bifidobacterium abundance in appropriate populations.

Bifidobacterial Dominance of the Gut in Early Life and Acquisition of Antimicrobial Resistance

Infants are vulnerable to an array of infectious diseases, and as the gut microbiome may serve as a reservoir of AMR for pathogens, reducing the levels of AMR in infants is important to infant health. This study demonstrates that high levels of Bifidobacterium are associated with reduced levels of AMR in early life and suggests that probiotic interventions to increase infant Bifidobacterium levels have the potential to reduce AMR in infants. However, this effect is not sustained at year 2 of age in Bangladeshi infants, underscoring the need for more detailed studies of the biogeography and timing of infant AMR acquisition.

Bifidobacterium species are important commensals capable of dominating the infant gut microbiome, in part by producing acids that suppress growth of other taxa. Bifidobacterium species are less prone to possessing antimicrobial resistance (AMR) genes (ARGs) than other taxa that may colonize infants. Given that AMR is a growing public health crisis and ARGs are present in the gut microbiome of humans from early life, this study examines the correlation between a Bifidobacterium-dominated infant gut microbiome and AMR levels, measured by a culture-independent metagenomic approach both in early life and as infants become toddlers. In general, Bifidobacterium dominance is associated with a significant reduction in AMR in a Bangladeshi cohort, both in the number of acquired AMR genes present and in the abundance of AMR genes. However, by year 2, Bangladeshi infants had no significant differences in AMR related to their early-life Bifidobacterium levels. A generalized linear model including all infants in a previously published Swedish cohort found a significant negative association between log-transformed total AMR and Bifidobacterium levels, thus confirming the relationship between Bifidobacterium levels and AMR. In both cohorts, there was no change between early-life and later-life AMR abundance in high-Bifidobacterium infants but a significant reduction in AMR abundance in low-Bifidobacterium infants. These results support the hypothesis that early Bifidobacterium dominance of the infant gut microbiome may help reduce colonization by taxa containing ARGs.

IMPORTANCE Infants are vulnerable to an array of infectious diseases, and as the gut microbiome may serve as a reservoir of AMR for pathogens, reducing the levels of AMR in infants is important to infant health. This study demonstrates that high levels of Bifidobacterium are associated with reduced levels of AMR in early life and suggests that probiotic interventions to increase infant Bifidobacterium levels have the potential to reduce AMR in infants. However, this effect is not sustained at year 2 of age in Bangladeshi infants, underscoring the need for more detailed studies of the biogeography and timing of infant AMR acquisition.