Increased risk of respiratory tract infections in children with Down syndrome: the consequence of an altered immune system

IgG1 glycosylation highlights premature aging in Down syndrome

Down syndrome (DS) is characterized by lowered immune competence and premature aging. We previously showed decreased antibody response following SARS-CoV-2 vaccination in adults with DS. IgG1 Fc glycosylation patterns are known to affect the effector function of IgG and are associated with aging. Here, we compare total and anti-spike (S) IgG1 glycosylation patterns following SARS-CoV-2 vaccination in DS and healthy controls (HC). Total and anti-Spike IgG1 Fc N-glycan glycoprofiles were measured in non-exposed adults with DS and controls before and after SARS-CoV-2 vaccination by liquid chromatography-mass spectrometry (LC-MS) of Fc glycopeptides. We recruited N = 44 patients and N = 40 controls. We confirmed IgG glycosylation patterns associated with aging in HC and showed premature aging in DS. In DS, we found decreased galactosylation (50.2% vs. 59.0%) and sialylation (6.7% vs. 8.5%) as well as increased fucosylation (97.0% vs. 94.6%) of total IgG. Both cohorts showed similar bisecting GlcNAc of total and anti-S IgG1 with age. In contrast, anti-S IgG1 of DS and HC showed highly comparable glycosylation profiles 28 days post vaccination. The IgG1 glycoprofile in DS exhibits strong premature aging. The combination of an early decrease in IgG1 Fc galactosylation and sialylation and increase in fucosylation is predicted to reduce complement activity and decrease FcγRIII binding and subsequent activation, respectively. The altered glycosylation patterns, combined with decreased antibody concentrations, help us understand the susceptibility to severe infections in DS. The effect of premature aging highlights the need for individuals with DS to receive tailored vaccines and/or vaccination schedules.

Exploring the Complex Interplay of Obesity, Allergic Diseases, and Sleep-Disordered Breathing in Children

This narrative review study investigates the correlations between obesity, allergies, and sleep-disordered breathing in pediatric populations. Searches for pertinent articles were conducted on the Medline PubMed Advanced Search Builder, Scopus, and Web of Science databases from unlimited to April 2024. Sleep-disordered breathing causes repeated upper airway obstructions, leading to apneas and restless sleep. Childhood obesity, which affects around 20% of children, is often associated with sleep-disordered breathing and allergies such as asthma and allergic rhinitis. It is distinguished between diet-induced obesity (resulting from excess of diet and physical inactivity) and genetic obesity (such as is seen in Down syndrome and Prader-Willi syndrome). In children with diet-induced obesity, chronic inflammation linked to weight can worsen allergies and increase the risk and severity of asthma and rhinitis. Furthermore, the nasal congestion typical of rhinitis can contribute to upper respiratory tract obstruction and obstructive sleep apnea. A vicious circle is created between asthma and sleep-disordered breathing: uncontrolled asthma and sleep-disordered breathing can worsen each other. In children with genetic obesity, despite alterations in the immune system, fewer allergies are observed compared to the broader population. The causes of this reduced allergenicity are unclear but probably involve genetic, immunological, and environmental factors. Additional research is necessary to elucidate the underlying mechanisms. The present narrative review study emphasizes the importance of jointly evaluating and managing allergies, obesity, and obstructive sleep apnea in children considering their close interconnection.

Cardiopulmonary Phenotypes and Protein Signatures in Children With Down Syndrome

Pulmonary disease, lower respiratory tract infection, and pneumonia are the largest causes of morbidity and mortality in individuals with Down syndrome (DS), but whether pulmonary diagnoses in children with DS are common and occur independently of cardiac disease and pulmonary hypertension (PH) is unknown. Cardiopulmonary phenotypes were examined in a cohort of 1248 children with DS. Aptamer-based proteomic analysis of blood was performed in a subset (n = 120) of these children. By the age of 10 years, half of the patients in this cohort (n = 634, 50.8%) had co-occurring pulmonary diagnoses. That proteins and related pathways were distinct between children with pulmonary diagnoses and those with cardiac disease and/or PH may indicate that pulmonary diagnoses appear to occur independently of cardiac disease and PH. Heparin sulfate-glycosaminoglycandegradation, nicotinate metabolism, and elastic fiber formation were ranked highest in the group with pulmonary diagnoses.

Altered peripheral blood leukocyte subpopulations, function, and gene expression in children with Down syndrome: implications for respiratory tract infection

OBJECTIVES

We tested the hypothesis that aberrant expression of Hsa21-encoded interferon genes in peripheral blood immune cells would correlate to immune cell dysfunction in children with Down syndrome (DS).

STUDY DESIGN

We performed flow cytometry to quantify peripheral blood leukocyte subtypes and measured their ability to migrate and phagocytose. In matched samples, we measured gene expression levels for constituents of interferon signaling pathways. We screened 49 children, of which 29 were individuals with DS.

RESULTS

We show that the percentages of two peripheral blood myeloid cell subtypes (alternatively-activated macrophages and low-density granulocytes) in children with DS differed significantly from typical children, children with DS circulate a very different pattern of cytokines vs. typical individuals, and higher expression levels of type III interferon receptor Interleukin-10Rb in individuals with DS correlated with reduced migratory and phagocytic capacity of macrophages.

CONCLUSIONS

Increased susceptibility to severe and chronic infection in children with DS may result from inappropriate numbers and subtypes of immune cells that are phenotypically and functionally altered due to trisomy 21 associated interferonopathy.

Partial loss of Sorting Nexin 27 resembles age- and Down syndrome-associated T cell dysfunctions

BACKGROUND

Sorting Nexin 27 (SNX27)-retromer complex facilitates cargo recycling from endosomes to the plasma membrane. SNX27 downregulation in neurons, as the result of Trisomy 21 (T21), has been linked with cognitive deficits due to impairment of AMPA and NMDA receptor recycling. Studies in human T cell lines likewise demonstrated that SNX27 regulates the correct delivery of cargoes to the immune synapse limiting the activation of pro-inflammatory pathways. Nevertheless, the physiological consequences of partial SNX27 loss in T cell homeostasis are still unclear.

RESULTS

In this study, we have explored the consequences of T cell specific partial SNX27 downregulation in mice. T cells with partial SNX27 deficiency show a marked deficit in the CD4+ T cell pool, a hallmark of aging in mice and humans, and a well-characterized comorbidity of individuals with Down syndrome (DS). When analyzed ex vivo, CD4+ T cells with partial SNX27 deletion demonstrate enhanced proliferation but diminished IL-2 production. In contrast, the CD8+ population show enhanced expression of pro-inflammatory cytokines and lytic enzymes.

CONCLUSIONS

This mouse model supports the relevance of SNX27 in the organization of the immune synapse, previously described in cell lines, as well as in the control of T cell homeostasis. Individuals with DS experiment an acceleration of the aging process, which particularly affects the immune and central nervous systems. Thus, we hypothesize that reduced SNX27 expression in DS could contribute to the dysregulation of these systems and further research in SNX27 will shed light on the molecular factors underlying the phenotypes observed in people with DS and its contribution to aging.

Establishing breast feeding in infants with Down syndrome: the FADES cohort experience

OBJECTIVE

To describe breastfeeding prevalence and maternal experience in infants with trisomy 21.

DESIGN

Longitudinal cohort study.

SETTING

Participants from UK recruited through websites, social media and local collaborators: neonatologists, community paediatricians and research nurses.

SUBJECTS

Infants under the age of 8 months with Down syndrome (DS) recruited to the Feeding and Autoimmunity in Down Syndrome Evaluation Study between 1 September 2014 and 31 August 2017. Seventy participants: median age 20 weeks (IQR 13-29 weeks) at initial questionnaire.

MAIN OUTCOME MEASURE

Breastfeeding prevalence at 6 weeks and 6 months among infants with DS.

RESULTS

The prevalence of exclusive breast feeding among study participants was similar to the general population (13/61, 21% vs 23% at 6 weeks, 2/54, 4% vs 1% at 6 months). However, the prevalence of breast feeding (exclusive or combination feeding) among the study participants was higher than the general population (39/61 64% vs 55% at 6 weeks, 32/59 54% vs 34% at 6 months).

CONCLUSION

Although there may be challenges in establishing breast feeding in infants with DS, our data suggest that exclusive breast feeding is possible for some, and the prevalence of breast feeding is comparable to the prevalence in the general population.

TRIAL REGISTRATION NUMBER

ISRCTN12415856.

Electrospun-Based Membranes as a Key Tool to Prevent Respiratory Infections

The use of electrospun meshes has been proposed as highly efficient protective equipment to prevent respiratory infections. Those infections can result from the activity of micro-organisms and other small dust particles, such as those resulting from air pollution, that impair the respiratory tract, induce cellular damage and compromise breathing capacity. Therefore, electrospun meshes can contribute to promoting air-breathing quality and controlling the spread of such epidemic-disrupting agents due to their intrinsic characteristics, namely, low pore size, and high porosity and surface area. In this review, the mechanisms behind the pathogenesis of several stressors of the respiratory system are covered as well as the strategies adopted to inhibit their action. The main goal is to discuss the performance of antimicrobial electrospun nanofibers by comparing the results already reported in the literature. Further, the main aspects of the certification of filtering systems are highlighted, and the expected technology developments in the industry are also discussed.

Beyond amyloid: Immune, cerebrovascular, and metabolic contributions to Alzheimer disease in people with Down syndrome

People with Down syndrome (DS) have increased risk of Alzheimer disease (AD), presumably conferred through genetic predispositions arising from trisomy 21. These predispositions necessarily include triplication of the amyloid precursor protein (APP), but also other Ch21 genes that confer risk directly or through interactions with genes on other chromosomes. We discuss evidence that multiple genes on chromosome 21 are associated with metabolic dysfunction in DS. The resulting dysregulated pathways involve the immune system, leading to chronic inflammation; the cerebrovascular system, leading to disruption of the blood brain barrier (BBB); and cellular energy metabolism, promoting increased oxidative stress. In combination, these disruptions may produce a precarious biological milieu that, in the presence of accumulating amyloid, drives the pathophysiological cascade of AD in people with DS. Critically, mechanistic drivers of this dysfunction may be targetable in future clinical trials of pharmaceutical and/or lifestyle interventions.

Heart Transplantation in Children With Down Syndrome

Background

Children with Down syndrome (DS) have a high risk of cardiac disease that may prompt consideration for heart transplantation (HTx). However, transplantation in patients with DS is rarely reported. This project aimed to collect and describe waitlist and post– HTx outcomes in children with DS.

Methods and Results

This is a retrospective case series of children with DS listed for HTx. Pediatric HTx centers were identified by their participation in 2 international registries with centers reporting HTx in a patient with DS providing detailed demographic, medical, surgical, and posttransplant outcome data for analysis. A total of 26 patients with DS were listed for HTx from 1992 to 2020 (median age, 8.5 years; 46% male). High‐risk or failed repair of congenital heart disease was the most common indication for transplant (N=18, 69%). A total of 23 (88%) patients survived to transplant. All transplanted patients survived to hospital discharge with a median posttransplant length of stay of 22 days. At a median posttransplant follow‐up of 2.8 years, 20 (87%) patients were alive, 2 (9%) developed posttransplant lymphoproliferative disorder, and 8 (35%) were hospitalized for infection within the first year. Waitlist and posttransplant outcomes were similar in patients with and without DS (P=non‐significant for all).

Conclusions

Waitlist and post‐HTx outcomes in children with DS selected for transplant listing are comparable to pediatric HTx recipients overall. Given acceptable outcomes, the presence of DS alone should not be considered an absolute contraindication to HTx.

Toxoplasma gondii Infection Among Institutionalized Children with Down syndrome in Sana'a city, Yemen: Implications of Low IgG Seroprevalence

Purpose

To assess the IgG seroprevalence of Toxoplasma gondii as an indicator of past exposure and immunity against infection among children with Down syndrome (DS) in Sana’a city, Yemen. This preliminary study is justified by the primary immunodeficiency of children with DS and the opportunistic nature of the parasite, considering the vague situation of anti-Toxoplasma IgG seroprevalence among children with DS because of neglecting its study on local and global scales.

Methods

This descriptive, facility-based, cross-sectional study was conducted among 107 children with DS hosted in six randomly selected rehabilitation centers for children with special needs in Sana’a city. Demographics of children and their mothers’ knowledge of toxoplasmosis were collected using a pre-designed, structured questionnaire. Anti-Toxoplasma IgG antibodies were measured in the sera of children using electrochemiluminescence assay.

Results

Of 107 children with DS, 3 (2.8%) were seropositive for anti-Toxoplasma IgG. Approximately two-thirds (71/106) of the mothers of children with DS were aware of toxoplasmosis. Of whom, 83.1% (59/71) were aware of its congenital complications.

Conclusion

The majority of children with DS in Sana’a city are seronegative for anti-Toxoplasma IgG, where the seropositivity rate is lower than 3.0%. Therefore, children with DS are non-immune and susceptible to the acquisition of primary infections during their life. Further analytical studies are recommended to determine whether the defective immune response of children with DS is associated with false seronegativity, to assess the role of their mothers’ knowledge in reducing their exposure to infection if they were confirmed truly seronegative and to identify the predictors of infection among them.

Hospital admissions in infants with Down syndrome: a record-linked population-based cohort study in Wales

BACKGROUND

Despite recent advances, mortality in children with Down syndrome remains five times higher than in the general population. This study aims to describe the burden, patterns and causes of hospital admissions in infants with Down syndrome, and compare this with infants without Down syndrome in a population-based cohort.

METHODS

This study used data from the Wales Electronic Cohort for Children, a cohort of all children born in Wales between 1990 and 2012. The cohort was generated from routine administrative data, linked to create an anonymised data set within the Secure Anonymised Information Linkage databank. This analysis is based on all infants born between January 2003 and January 2012 who were followed to their first birthday, a move out of Wales, death, or until 31 October 2012 (end of follow-up). Infants with Down syndrome were identified using the Congenital Anomaly Register and Information Service in Wales. Multivariable Cox regression was used to compare the time to first hospital admission. Admission codes were used to identify the commonest indications for hospitalisation and to determine the presence of other congenital anomalies.

RESULTS

We included 324 060 children, 356 of whom had Down syndrome. Of infants with Down syndrome, 80.3% had at least one hospital inpatient admission during the first year of life, compared with 32.9% of infants without Down syndrome. These first admissions were earlier [median of 6 days interquartile range (IQR) (3, 72) compared with 45 days [IQR 6, 166)] and longer [median of 4 days (IQR 1, 15) compared with 1 day (IQR 0, 3)] than in infants without Down syndrome. The most common causes of admissions were congenital abnormalities, respiratory diseases, conditions originating in the perinatal period and infectious diseases. The presence of other congenital abnormalities increased hospitalisations in all infants, but more so in infants with Down syndrome who spent a median of 21 days in hospital (IQR 11, 47) during their first year of life.

CONCLUSION

Infants with Down syndrome are at high risk for early, more frequent and longer hospital admissions. Congenital heart disease and respiratory infections remain a major burden in this population. More research is needed to understand how to better manage these conditions particularly in the first month of life when most admissions occur.

COVID-19 in Children with Down Syndrome: Data from the Trisomy 21 Research Society Survey

Adults with Down Syndrome (DS) are at higher risk for severe outcomes of coronavirus disease 2019 (COVID-19) than the general population, but evidence is required to understand the risks for children with DS, which is necessary to inform COVID-19 shielding advice and vaccination priorities. We aimed to determine the epidemiological and clinical characteristics of COVID-19 in children with DS. Using data from an international survey obtained from a range of countries and control data from the United States, we compared the prevalence of symptoms and medical complications and risk factors for severe outcomes between DS and non-DS paediatric populations with COVID-19. Hospitalised COVID-19 patients <18 years with DS had a higher incidence of respiratory symptoms, fever, and several medical complications from COVID-19 than control patients without DS <18 years. Older age, obesity, and epilepsy were significant risk factors for hospitalisation among paediatric COVID-19 patients with DS, and age and thyroid disorder were significant risk factors for acute respiratory distress syndrome. Mortality rates were low in all paediatric COVID-19 patients (with and without DS), contrasting with previous findings in adults with DS (who exhibit higher mortality than those without DS). Children with DS are at increased risk for more severe presentations of COVID-19. Efforts should be made to ensure the comprehensive and early detection of COVID-19 in this population and to identify children with DS who present comorbidities that pose a risk for a severe course of COVID-19. Our results emphasize the importance of vaccinating children with DS as soon as they become eligible.

Unexpected death in children with severe congenital heart defects in Norway 2004-2016

AIMS

Updated knowledge on the rates and causes of death among children with severe congenital heart defects (CHDs) is needed to further improve treatment and survival. This study investigated nationwide mortality rates in children with severe CHDs with an emphasis on unexpected mortality unrelated to cardiac intervention.

METHODS AND RESULTS

Data on all pregnancies and live-born children in Norway from 2004 to 2016 were obtained from national registries, the Oslo University Hospital's Clinical Registry for CHDs and medical records. Among 2359 live-born children with severe CHDs, 234 (10%) died before 2 years of age. Of these, 109 (46%) died in palliative care, 58 (25%) died of causes related to a cardiac intervention and 67 (29%) died unexpectedly and unrelated to a cardiac intervention, either before (n=26) or following (n=41) discharge after a cardiac intervention. Comorbidity (38/67, 57%), persistent low oxygen saturation (SaO₂; <95%; 41/67, 61%), staged surgery (21/41, 51%), residual cardiac defects (22/41, 54%) and infection (36/67, 54%) were frequent in children who died unexpectedly unrelated to an intervention. Two or more of these factors were present in 62 children (93%). The medical reports at hospital discharge lacked information on follow-up in many patients who died unexpectedly.

CONCLUSIONS

The numbers of unexpected deaths unrelated to cardiac intervention in children <2 years of age without comorbidity were low in Norway. However, close follow-up is recommended for infants with comorbidities, persistent low oxygen saturation, staged surgery or residual cardiac defects, particularly when an infection occurs.

Mechanistic Analysis of Age-Related Clinical Manifestations in Down Syndrome

Down syndrome (DS) is the most common genetic cause of Alzheimer's disease (AD) due to trisomy for all or part of human chromosome 21 (Hsa21). It is also associated with other phenotypes including distinctive facial features, cardiac defects, growth delay, intellectual disability, immune system abnormalities, and hearing loss. All adults with DS demonstrate AD-like brain pathology, including amyloid plaques and neurofibrillary tangles, by age 40 and dementia typically by age 60. There is compelling evidence that increased APP gene dose is necessary for AD in DS, and the mechanism for this effect has begun to emerge, implicating the C-terminal APP fragment of 99 amino acid (β-CTF). The products of other triplicated genes on Hsa21 might act to modify the impact of APP triplication by altering the overall rate of biological aging. Another important age-related DS phenotype is hearing loss, and while its mechanism is unknown, we describe its characteristics here. Moreover, immune system abnormalities in DS, involving interferon pathway genes and aging, predispose to diverse infections and might modify the severity of COVID-19. All these considerations suggest human trisomy 21 impacts several diseases in an age-dependent manner. Thus, understanding the possible aging-related mechanisms associated with these clinical manifestations of DS will facilitate therapeutic interventions in mid-to-late adulthood, while at the same time shedding light on basic mechanisms of aging.

Lower airway microbiota in children with Down syndrome compared to controls with similar respiratory symptomatology

BACKGROUND

Children with Down syndrome (DS) often present with chronic or recurrent respiratory symptoms and generally have a more severe and prolonged disease course in case of infection. This can be caused by anatomical and/or immunological predisposition. With this study, we aim to compare microbial composition in the lower airways of patients with DS versus controls, to see if we can explain the difference in disease course.

METHODS

All endoscopic procedures under general anesthesia in patients with DS were reviewed retrospectively. We compared the microbiological data from bronchoalveolar lavage fluid (BALF) cultures (when available) to a cohort of children with chronic respiratory symptoms but without any other relevant medical history.

RESULTS

Endoscopic data were available for 65 DS patients, BAL cultures for 47 out of 65 patients (72%). The "control" group consisted of 150 children without significant underlying disease, who were matched for age and sex. BAL culture results were available for 135 out of 150 patients (90%). Microorganisms were categorized and compared between both groups, with no statistical differences. Among the microorganisms tested, the most frequently reported were typical bacteria such as Haemophilus influenzae, Moraxella catarrhalis, Streptococci and Staphylococci.

CONCLUSIONS

No significant differences in lower airways microbial composition of children with DS and chronic respiratory symptoms were found when compared to controls presenting similar symptomatology. A suggestion for future research may be to investigate possible differences in drug sensitivity.

Immune Dysregulation and the Increased Risk of Complications and Mortality Following Respiratory Tract Infections in Adults With Down Syndrome

The risk of severe outcomes following respiratory tract infections is significantly increased in individuals over 60 years, especially in those with chronic medical conditions, i.e., hypertension, diabetes, cardiovascular disease, dementia, chronic respiratory disease, and cancer. Down Syndrome (DS), the most prevalent intellectual disability, is caused by trisomy-21 in ~1:750 live births worldwide. Over the past few decades, a substantial body of evidence has accumulated, pointing at the occurrence of alterations, impairments, and subsequently dysfunction of the various components of the immune system in individuals with DS. This associates with increased vulnerability to respiratory tract infections in this population, such as the influenza virus, respiratory syncytial virus, SARS-CoV-2 (COVID-19), and bacterial pneumonias. To emphasize this link, here we comprehensively review the immunobiology of DS and its contribution to higher susceptibility to severe illness and mortality from respiratory tract infections.

Down syndrome and congenital heart disease: perioperative planning and management

Approximately 50% of newborns with Down syndrome have congenital heart disease. Non-cardiac comorbidities may also be present. Many of the principles and strategies of perioperative evaluation and management for patients with congenital heart disease apply to those with Down syndrome. Nevertheless, careful planning for cardiac surgery is required, evaluating for both cardiac and noncardiac disease, with careful consideration of the risk for pulmonary hypertension. In this manuscript, for children with Down syndrome and hemodynamically significant congenital heart disease, we will summarize the epidemiology of heart defects that warrant intervention. We will review perioperative planning for this unique population, including anesthetic considerations, common postoperative issues, nutritional strategies, and discharge planning. Special considerations for single ventricle palliation and heart transplantation evaluation will also be discussed. Overall, the risk of mortality with cardiac surgery in pediatric patients with Down syndrome is no more than the general population, except for those with functional single ventricle heart defects. Underlying comorbidities may contribute to postoperative complications and increased length of stay. A strong understanding of cardiac and non-cardiac considerations in children with Down syndrome will help clinicians optimize perioperative care and long-term outcomes.

Post-infectious inflammatory syndrome associated with SARS-CoV-2 in a paediatric patient with Down syndrome

Neurological complications of SARS-CoV-2 continue to be recognised. In children, neurological phenomenon has been reported generally in the acute infectious period. It is possible that SARS-CoV-2 could trigger an immune-mediated post-infectious phenomenon. Here, we present a unique case of post-infectious marantic cardiac lesion causing cerebrovascular accident in a patient with Down syndrome.

Prevalence and Loads of Torquetenovirus in the European MARK-AGE Study Population

Torquetenovirus (TTV) viremia has been associated with increased mortality risk in the elderly population. This work aims to investigate TTV viremia as a potential biomarker of immunosenescence. We compared levels of circulating TTV in 1813 participants of the MARK-AGE project, including human models of delayed (offspring of centenarians [GO]) and premature (Down syndrome [DS]) immunosenescence. The TTV load was positively associated with age, cytomegalovirus (CMV) antibody levels, and the Cu/Zn ratio and negatively associated with platelets, total cholesterol, and total IgM. TTV viremia was highest in DS and lowest in GO, with intermediate levels in the SGO (spouses of GO) and RASIG (Randomly Recruited Age-Stratified Individuals From The General Population) populations. In the RASIG population, TTV DNA loads showed a slight negative association with CD3+T-cells and CD4+T-cells. Finally, males with ≥4log TTV copies/mL had a higher risk of having a CD4/CD8 ratio<1 than those with lower viremia (odds ratio [OR] = 2.85, 95% confidence interval [CI]: 1.06-7.62), as well as reduced CD3+ and CD4+T-cells compared to males with lower replication rates (<4log), even after adjusting for CMV infection. In summary, differences in immune system preservation are reflected in the models of delayed and premature immunosenescence, displaying the best and worst control over TTV replication, respectively. In the general population, TTV loads were negatively associated with CD4+ cell counts, with an increased predisposition for an inverted CD4/CD8 ratio for individuals with TTV loads ≥4log copies/mL, thus promoting an immune risk phenotype.

Medical conditions of children and young people with Down syndrome

BACKGROUND

The life expectancy of people with Down syndrome (DS) has significantly increased in the last decades. We describe the congenital malformations and main comorbidities of a cohort of children and young people with DS and analyse their differences according to age and gender groups.

METHODS

This retrospective cross-sectional study was conducted at DS centre of Bambino Gesù Children's Hospital in Rome (Italy). The period for reviewing all electronic health records ran from July 2016 to September 2017. We collected data on clinical conditions and compared them with the general paediatric population. Moreover, we compared the main comorbidities, dental diseases and body mass index data between age groups.

RESULTS

Seven hundred sixty-three children and young people with DS included in this study were aged 7.45 ± 5.49 years. Gender distribution included 58.19% male patients. The majority of our population (71.04%) came from central regions of Italy. Respiratory diseases (19%), congenital heart defects (72.23%), malocclusions (58.62%), astigmatism (20.31%), farsightedness (16.51%), near-sightedness (12.19%) and autoimmune hypothyroidism (3.28%) were more frequent in our population compared with the typical paediatric population. Upper respiratory tract infections and underweight were significantly more frequent in the youngest children, whereas dental diseases, refractive errors, obesity and autoimmune hypothyroidism increased over age.

CONCLUSIONS

Children and young people with DS present a high prevalence of potentially treatable medical conditions making multidisciplinary teams a mandatory need for this population.

Effect of antibiotics in preventing hospitalizations from respiratory tract infections in children with Down syndrome

BACKGROUND

Children with Down syndrome (DS) are at high risk of respiratory tract infections (RTIs) due to anatomical variations, comorbidities, and immune system immaturity. Evidence on interventions to reduce this risk is incomplete. This study aims to quantify the effect of antibiotics prescribed for RTIs in primary care on the subsequent risk of RTI-related hospitalization for children with DS versus controls.

METHODS

We conducted a retrospective cohort study of 992 children with DS and 4874 controls managed by UK National Health Service General Practitioners (GPs) and hospitals as identified in CALIBER (Clinical disease research using LInked Bespoke studies and Electronic health Records), 1997-2010. Univariate and multivariate logistic regression were undertaken.

RESULTS

In children with DS, the prescription of antibiotics following an RTI-related GP consultation did not significantly reduce the risk of RTI-related hospitalization in the subsequent 28 days (risk with antibiotics, 1.8%; without, 2.5%; risk ratio, 0.699; 95% confidence interval, 0.471-1.036). Subgroup analyses showed a risk reduction only in infants with DS, after adjustment for covariates. There was no reduction in risk for controls, overall or across subgroups.

CONCLUSIONS

In conclusion, while prescription of antibiotics following RTI-related GP consultations were effective for infants with DS in reducing subsequent RTI-related hospitalization, this was not the case for older children with DS. We would encourage further high-quality cohort and randomized controlled trials to interrogate this finding, and to examine the impact of antibiotics on other endpoints, including symptom duration.

Proteomics Study of Peripheral Blood Mononuclear Cells in Down Syndrome Children

Down syndrome (DS) is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans, which results from the triplication of chromosome 21. To search for biomarkers for the early detection and exploration of the disease mechanisms, here, we investigated the protein expression signature of peripheral blood mononuclear cells (PBMCs) in DS children compared with healthy donors (HD) by using an in-depth label-free shotgun proteomics approach. Identified proteins are found associated with metabolic pathways, cellular trafficking, DNA structure, stress response, cytoskeleton network, and signaling pathways. The results showed that a well-defined number of dysregulated pathways retain a prominent role in mediating DS pathological features. Further, proteomics results are consistent with published study in DS and provide evidences that increased oxidative stress and the increased induction of stress related response, is a participant in DS pathology. In addition, the expression levels of some key proteins have been validated by Western blot analysis while protein carbonylation, as marker of protein oxidation, was investigated. The results of this study propose that PBMCs from DS children might be in an activated state where endoplasmic reticulum stress and increased production of radical species are one of the primary events contributing to multiple DS pathological features.

Universal palivizumab prophylaxis for children with Down syndrome in Japan: analysis with interrupted time-series

Down syndrome (DS) is an independent risk factor for severe respiratory syncytial virus (RSV) infection. Palivizumab - passive immunization for RSV - is the only pharmacological measure for preventing severe disease. In most countries, palivizumab is indicated in young children with congenital heart disease, premature birth, and chronic lung disease. In Japan, since 2013, children with DS, but without such "standard" risk factors, have been able to receive insurance-covered palivizumab prophylaxis, but its effectiveness of policy is unknown. From a nationwide database, we extracted data of children with DS who hospitalized for RSV-related lower respiratory infections (LRTIs), from April 2010 to January 2019. Using an interrupted time-series design, we analyzed data from before and after the introduction of the universal palivizumab prophylaxis program for DS children in Japan. As a result, we identified a total of 152 RSV-related LRTIs in 147 children hospitalized with DS. With time-series analysis, we did not observe a significant change in both level (-1.07, P = .11) and slope (0.26 per 12 months, P = .30), before and after 2013. In summary, the expansion of the palivizumab prophylaxis program to all children with DS in Japan was not associated with a reduction in RSV-related hospitalization in these children.

Respiratory Syncytial Virus-related Death in Children With Down Syndrome: The RSV GOLD Study

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of mortality in children younger than 5 years worldwide. Systematic reviews have shown that Down syndrome (DS) is an independent risk factor for severe RSV infection. We aimed to describe demographic and clinical characteristics of children with DS who died with RSV infection.

METHODS

We performed a retrospective case series in which data were shared by individual researchers, research networks and physicians worldwide as part of the RSV Global Online Database study. We included children with DS who died when younger than 5 years of age with laboratory-confirmed RSV infection.

RESULTS

We included 53 children with DS and RSV-related mortality from 20 countries in 5 continents. Five (9.4%) children were from low-income or lower-middle-income countries. Median age at time of death was 6.0 months [interquartile range (IQR): 3.00-12.0]. Thirteen (24.5%) children were born term and had no other risk factors for severe RSV disease. In total, 36 (67.9%) children had congenital heart disease, 8 (15.1%) had chronic lung disease and 1 (1.9%) had congenital immunodeficiency. Duration of hospitalization was significantly longer for children with DS compared with children without DS [median length of stay, 13 days (IQR: 6.8-21.0) vs. 8 days (IQR: 3.0-18.5), P=0.005].

CONCLUSIONS

One-fourth of children with DS and RSV-confirmed death did not have risk factors for severe RSV disease, indicating that DS is an important risk factor for RSV-related mortality. Age distribution at time of death demonstrates that maternal vaccination would not be sufficient to protect children with DS against RSV-related mortality.

The prevalence of lower airway anomalies in children with Down syndrome compared to controls

INTRODUCTION

Children with Down syndrome (DS) often present with chronic respiratory symptoms. Congenital airway anomalies have been described but data about prevalence is scarce and a comparison to controls is lacking. We aim to compare the endoscopic and clinical data of children with DS to controls without significant medical history.

METHODS

All endoscopic procedures under general anesthesia (broncho- and/or direct laryngoscopy) in patients with DS were reviewed. We compared clinical and endoscopic data to a cohort of children with respiratory symptoms but without any other relevant medical history.

RESULTS

Endoscopic data were available for 65 patients with DS. The median age was 2.9 years (range: 0.2-17), 63% were boys. The most common clinical presentation was recurrent respiratory infections (37%). Other major symptoms were chronic cough and/or noisy breathing (23%) and stridor (20%). Endoscopy was normal in 29% of patients. The largest group of patients (44%) had some form of airway malacia. Tracheal bronchus and subglottic stenosis were each isolated findings in 3.1% of patients. Twenty percent presented with combined airway anomalies. The control group consisted of 150 children (matched for age and sex) without significant underlying disease. The most common presentations were chronic cough and/or noisy breathing (29%), persistent radiographic abnormalities (20%), and suspicion of aspiration of a foreign body (15%). In the majority of controls (68%), no airway anomaly was found. Other findings were malacia (22%), tracheal bronchus (1%), and subglottic stenosis (1%). A combined anomaly was found in 5%.

CONCLUSION

Congenital airway anomalies were seen in 71% of patients with DS, compared with 32% of controls. Combined anomalies are more frequent in DS. Complete lower airway endoscopy is recommended in patients with DS as it may influence therapeutic decision-making.

Down Syndrome and COVID-19: A Perfect Storm?

People with Down syndrome show signs of chronic immune dysregulation, including a higher prevalence of autoimmune disorders, increased rates of hospitalization during respiratory viral infections, and higher mortality rates from pneumonia and sepsis. At the molecular and cellular levels, they show markers of chronic autoinflammation, including interferon hyperactivity, elevated levels of many inflammatory cytokines and chemokines, and changes in diverse immune cell types reminiscent of inflammatory conditions observed in the general population. However, the impact of this immune dysregulation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and CoV disease of 2019 (COVID-19) remains unknown. This Perspective outlines why individuals with Down syndrome should be considered an at-risk population for severe COVID-19. Specifically, the immune dysregulation caused by trisomy 21 may result in an exacerbated cytokine release syndrome relative to that observed in the euploid population, thus justifying additional monitoring and specialized care for this vulnerable population.

Respiratory tract infection-related healthcare utilisation in children with Down's syndrome

Purpose

Children with Down’s syndrome (DS) are prone to respiratory tract infections (RTIs) due to anatomical variation, immune system immaturity and comorbidities. However, evidence on RTI-related healthcare utilisation, especially in primary care, is incomplete. In this retrospective cohort study, we use routinely collected primary and secondary care data to quantify RTI-related healthcare utilisation in children with DS and matched controls without DS.

Methods

Retrospective cohort study of 992 children with DS and 4874 matched controls attending English general practices and hospitals as identified in Clinical disease research using LInked Bespoke studies and Electronic health Records (CALIBER) from 1997 to 2010. Poisson regression was used to calculate consultation, hospitalisation and prescription rates, and rate ratios. Wald test was used to compare risk of admission following consultation. The Wilcoxon rank–sum test was used to compare length of stay by RTI type and time-to-hospitalisation.

Results

RTI-related healthcare utilisation is significantly higher in children with DS than in controls in terms of GP consultations (adjusted RR 1.73; 95% CI 1.62–1.84), hospitalisations (adjusted RR 5.70; 95% CI 4.82–6.73), and antibiotic prescribing (adjusted RR 2.34; 95% CI 2.19–2.49). Two percent of children with DS presenting for an RTI-related GP consultation were subsequently admitted for an RTI-related hospitalisation, compared to 0.7% in controls.

Conclusions

Children with DS have higher rates of GP consultations, hospitalisations and antibiotic prescribing compared to controls. This poses a significant burden on families. Further research is recommended to characterise healthcare behaviours and clinical decision-making, to optimise care for this at risk group.

Electronic supplementary material

The online version of this article (10.1007/s15010-020-01408-5) contains supplementary material, which is available to authorized users.

Effects of Pidotimod on recurrent respiratory infections in children with Down syndrome: a retrospective Italian study

BACKGROUND

Children with Down syndrome (DS) show a high susceptibility to recurrent infections (RI), caused by immune defects and abnormalities of the airways. Our goal was to investigate the effects of Pidotimod on RI prevention in children with DS, comparing immune and clinical parameters before (T0) and after (T1) the treatment with Pidotimod.

METHODS

The study was conducted at the Down syndrome outpatient Center of Bambino Gesù Children's Hospital, in Rome. We reviewed the medical records of all children with a positive history for RI and who received oral prophylaxis of Pidotimod from September 2016 to February 2017.

RESULTS

Thirty-three children met the inclusion criteria (males: 51.5%; average age: 6 years ±SD: 3). We found a significant decrease in the number of children with upper respiratory infections (82% at T0 vs 24% at T1; p = 0,0001) and with lower respiratory infections (36% at T0 vs 9% at T1; p = 0.003) after treatment with Pidotimod. We also demonstrated a significant decrease in the number of children hospitalized for respiratory infections (18% at T0 vs 3% at T1; p = 0.03). We measured T and B cells in the peripheral blood and B cell function in vitro at T0 and T1. We found that the response to CpG improved at T1. A significant increase of B cell frequency (p = 0.0009), B cell proliferation (p = 0.0278) and IgM secretion (p = 0.0478) were observed in children with DS after treatment.

CONCLUSIONS

Our results provided evidence that Pidotimod may be able to prevent RI in children with Down syndrome.

Oral management of a patient with down syndrome and agammaglobulinemia: a case report

BACKGROUND

Down syndrome is characterized by a variety of dysmorphic features and congenital malformations, such as congenital heart disease, gastrointestinal disease, and other conditions like leukemia and autoimmune disorders. Patients with Down syndrome are highly prone to respiratory tract infections, which might be fatal to them. However, there are only few available data on patients diagnosed with Down syndrome and agammaglobulinemia. In this report, we describe a case of successful prevention of post-dental treatment complications (e.g., pneumonia and other bacterial infections) in a patient with Down syndrome and agammaglobulinemia.

CASE PRESENTATION

A 43-year-old man with Down syndrome, untreated agammaglobulinemia, and a history of recurrent pneumonia, was referred to our clinic for tooth mobility. To reduce the risk of post-operative infections, gammaglobulin treatment and prophylactic administration of antibiotics was scheduled before the dental procedure. Furthermore, the dental treatment, which included a filling and extractions, was conducted under general anesthesia and with the supervision of a hematologist. The dental procedures were successfully performed without any post-operative infection, and the patient is undergoing follow-up care.

CONCLUSIONS

The purpose of this case report was to recommend a close liaison between physicians and dentists who may encounter a similar case, and to emphasize the importance of improving oral health of immunodeficient patients to prevent infections caused by oral microbial flora.

Down syndrome

Trisomy 21, the presence of a supernumerary chromosome 21, results in a collection of clinical features commonly known as Down syndrome (DS). DS is among the most genetically complex of the conditions that are compatible with human survival post-term, and the most frequent survivable autosomal aneuploidy. Mouse models of DS, involving trisomy of all or part of human chromosome 21 or orthologous mouse genomic regions, are providing valuable insights into the contribution of triplicated genes or groups of genes to the many clinical manifestations in DS. This endeavour is challenging, as there are >200 protein-coding genes on chromosome 21 and they can have direct and indirect effects on homeostasis in cells, tissues, organs and systems. Although this complexity poses formidable challenges to understanding the underlying molecular basis for each of the many clinical features of DS, it also provides opportunities for improving understanding of genetic mechanisms underlying the development and function of many cell types, tissues, organs and systems. Since the first description of trisomy 21, we have learned much about intellectual disability and genetic risk factors for congenital heart disease. The lower occurrence of solid tumours in individuals with DS supports the identification of chromosome 21 genes that protect against cancer when overexpressed. The universal occurrence of the histopathology of Alzheimer disease and the high prevalence of dementia in DS are providing insights into the pathology and treatment of Alzheimer disease. Clinical trials to ameliorate intellectual disability in DS signal a new era in which therapeutic interventions based on knowledge of the molecular pathophysiology of DS can now be explored; these efforts provide reasonable hope for the future.

Using mouse models to understand Alzheimer's disease mechanisms in the context of trisomy of chromosome 21

People who have Down syndrome are at significantly elevated risk of developing early onset Alzheimer's disease that causes dementia (AD-DS). Here we review recent progress in modeling the development of AD-DS in mouse models. These studies provide insight into mechanisms underlying Alzheimer's disease and generate new clinical research questions. In addition, they suggest potential new targets for disease prevention therapies.

Trisomy 21 activates the kynurenine pathway via increased dosage of interferon receptors

Trisomy 21 (T21) causes Down syndrome (DS), affecting immune and neurological function by ill-defined mechanisms. Here we report a large metabolomics study of plasma and cerebrospinal fluid, showing in independent cohorts that people with DS produce elevated levels of kynurenine and quinolinic acid, two tryptophan catabolites with potent immunosuppressive and neurotoxic properties, respectively. Immune cells of people with DS overexpress IDO1, the rate-limiting enzyme in the kynurenine pathway (KP) and a known interferon (IFN)-stimulated gene. Furthermore, the levels of IFN-inducible cytokines positively correlate with KP dysregulation. Using metabolic tracing assays, we show that overexpression of IFN receptors encoded on chromosome 21 contribute to enhanced IFN stimulation, thereby causing IDO1 overexpression and kynurenine overproduction in cells with T21. Finally, a mouse model of DS carrying triplication of IFN receptors exhibits KP dysregulation. Together, our results reveal a mechanism by which T21 could drive immunosuppression and neurotoxicity in DS.

Altered Toll-Like Receptor Signalling in Children with Down Syndrome

Toll-like receptors (TLRs) are the key in initiating innate immune responses. TLR2 is crucial in recognising lipopeptides from gram-positive bacteria and is implicated in chronic inflammation. Children with Down syndrome (DS) are prone to infections from these pathogens and have an increased risk of autoimmunity. Sparstolonin B (SsnB) is a TLR antagonist which attenuates cytokine production and improves outcomes in sepsis. We hypothesised that TLR signalling may be abnormal in children with DS and contribute to their clinical phenotype. We evaluated TLR pathways in 3 ways: determining the expression of TLR2 on the surface of neutrophils and monocytes by flow cytometry, examining the gene expression of key regulatory proteins involved in TLR signal propagation, MyD88, IRAK4, and TRIF, by quantitative PCR, and lastly determining the cytokine production by ELISA following immunomodulation with proinflammatory stimuli (lipopolysaccharide (LPS), Pam3Csk4) and the anti-inflammatory agent SsnB. We report TLR2 expression being significantly increased on neutrophils, total monocytes, and intermediate and nonclassical monocytes in children with DS (n = 20, mean age 8.8 ± SD 5.3 years, female n = 11) compared to controls (n = 15, mean age 6.2 ± 4.2 years, female n = 5). At baseline, the expression of MyD88 was significantly lower, and TRIF significantly raised in children with DS. The TLR antagonist SsnB was effective in reducing TLR2 and CD11b expression and abrogating cytokine production in both cohorts. We conclude that TLR signalling and the TLR2 pathway are dysregulated in DS, and this disparate innate immunity may contribute to chronic inflammation in DS. SsnB attenuates proinflammatory mediators and may be of therapeutic benefit.

Infection risk among adults with down syndrome: a two group series of 101 patients in a tertiary center

Background

Down syndrome (DS) is the most common form of viable chromosomal abnormality. DS is associated with recurrent infections, auto-immunity and malignancies in children. Little is known about immunity and infections in DS at adulthood.

Methods

We studied two separate group of adults (> 18 years old) with DS in a single referral tertiary center (Strasbourg University Hospital). The first group included 37 ambulatory DS patients between November 2014 and May 2017. We analyzed exhaustive serological and immunobiological parameters, at one point, together with the prevalence of infections, autoimmune manifestations and malignancies. The second group included 64 hospitalized patients (138 stays) in the same center, between January 2005 and December 2016.

Results

One hundred and one adult patients with DS were included. Unlike children and despite a global lymphopenia, adults with DS underwent few infections in our ambulatory group. They did not experience any malignancy and, apart from hypothyroidism, they presented only occasional autoimmune manifestations. Hospitalized DS patients were older than ambulatory ones (median age 47 years (18–73) vs. 27 (18–52), p < 0.0001) and admitted mostly for infections (76.8%). Infections were associated with epilepsy and dementia (OR 6.5 (2.2–19), p = 0.001; p = 0.0006 in multivariate analysis) and higher mortality (OR 7.4 (1.4–37), p = 0.01).

Conclusion

Despite persistent immunobiological abnormalities at adulthood, young ambulatory adults with DS remain healthy with a low rate of infections. Infections are associated with neurological degeneration and increase the mortality arguing for a dedicated support of older DS patients.

Trial registration

ClinicalTrials.gov: NCT01663675 (August 13, 2012). Hospital Clinical Research Program (PHRC): number 2012-A00466–37 (Dr Y. Alembik).

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0989-x) contains supplementary material, which is available to authorized users.

Hospitalization for Respiratory Syncytial Virus in Children with Down Syndrome Less than 2 Years of Age: A Systematic Review and Meta-Analysis

OBJECTIVES

To compare the respiratory syncytial virus (RSV)-related hospitalization rate, hospital length of stay (LOS), and need for assisted ventilation in children aged <2 years with Down syndrome and those without Down syndrome.

STUDY DESIGN

MEDLINE, Embase, and CINAHL databases were searched from inception up to December 2017. Studies that provided data on RSV-related hospitalization in children aged <2 years with Down syndrome and those without Down syndrome were included. Data were independently extracted in pairs by 2 reviewers and synthesized with random-effects meta-analysis.

RESULTS

In 10 studies including a total of 1 748 209 children, 12.6% of the children with Down syndrome (491 of 3882) were hospitalized with RSV infection. The presence of Down syndrome was associated with a significantly higher risk of RSV-related hospitalization (relative risk [RR], 6.06; 95% CI, 4.93-7.45; I² = 65%; Grading of Recommendations, Assessment, Development and Evaluation [GRADE], moderate). RSV-related LOS (mean difference, 2.11 days; 95% CI, 1.47-2.75 days; I² = 0%; GRADE, low), and the need for assisted ventilation (RR, 5.82; 95% CI, 1.81-18.69; I² = 84%; GRADE, low). Children with Down syndrome without congenital heart disease (RR, 6.31; 95% CI, 4.83-8.23; GRADE, moderate) also had a significantly higher risk of RSV-related hospitalization. The risk of RSV-related hospitalization remained significant in the subgroup of children aged <1 year (RR, 6.25; 95% CI, 4.71-8.28; GRADE, high).

CONCLUSION

RSV-related hospitalization, hospital LOS, and the need for assisted ventilation are significantly higher in children with Down syndrome aged <2 years compared with those without Down syndrome. The results should prompt reconsideration of the need for routine RSV prophylaxis in children with Down syndrome up to 2 years of age.

Underlying factors of recurrent infections in patients with down syndrome

Down syndrome is the most common chromosomal aberration. Patientswith Down syndrome suffer more infections than those without the disease. Underlying immunological disorders are consideredto be the reason for the increasing frequency of infections in patients with Down syndrome. In addition, some anatomical abnormalities in the respiratory tractaccompanying Down syndrome can disturb the innate immunity and contribute to the increase in infection rate. Respiratory tract infections are one of the most common causes of mortality in patients with Down syndrome. Awareness of the underlying reason for frequent respiratory tract infections should result in a decrease in mortality among these patients and contribute to an improvementin their quality of life.

Morphine Pharmacokinetics in Children With Down Syndrome Following Cardiac Surgery

OBJECTIVES

To assess if morphine pharmacokinetics are different in children with Down syndrome when compared with children without Down syndrome.

DESIGN

Prospective single-center study including subjects with Down syndrome undergoing cardiac surgery (neonate to 18 yr old) matched by age and cardiac lesion with non-Down syndrome controls. Subjects were placed on a postoperative morphine infusion that was adjusted as clinically necessary, and blood was sampled to measure morphine and its metabolites concentrations. Morphine bolus dosing was used as needed, and total dose was tracked. Infusions were continued for 24 hours or until patients were extubated, whichever came first. Postinfusion, blood samples were continued for 24 hours for further evaluation of kinetics. If patients continued to require opioid, a nonmorphine alternative was used. Morphine concentrations were determined using a unique validated liquid chromatography tandem-mass spectrometry assay using dried blood spotting as opposed to large whole blood samples. Morphine concentration versus time data was modeled using population pharmacokinetics.

SETTING

A 16-bed cardiac ICU at an university-affiliated hospital.

PATIENTS

Forty-two patients (20 Down syndrome, 22 controls) were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The pharmacokinetics of morphine in pediatric patients with and without Down syndrome following cardiac surgery were analyzed. No significant difference was found in the patient characteristics or variables assessed including morphine total dose or time on infusion. Time mechanically ventilated was longer in children with Down syndrome, and regarding morphine pharmacokinetics, the covariates analyzed were age, weight, presence of Down syndrome, and gender. Only age was found to be significant.

CONCLUSIONS

This study did not detect a significant difference in morphine pharmacokinetics between Down syndrome and non-Down syndrome children with congenital heart disease.

National cohort study showed that infants with Down's syndrome faced a high risk of hospitalisation for the respiratory syncytial virus

AIM

The respiratory syncytial virus (RSV) is a leading cause of hospitalisation in infants. We investigated this risk in children with Down's syndrome under two years of age, adjusted for other known risk factors.

METHODS

This national, retrospective 1:2 matched cohort study comprised all Swedish children born with Down's from 2006 to 2011, who were each randomly matched to two controls without Down's. Data on RSV hospitalisation and risk factors for RSV were obtained from national registers. The risk of RSV hospitalisation was assessed using multivariable Cox regression with pairwise stratification.

RESULTS

The study comprised 814 children with Down's and 1628 controls. We found that 82 children with Down's (10.1%) and 22 controls (1.4%) were hospitalised for RSV. The hazard ratio for children with Down's was 4.00 (95% confidence interval 1.58-10.13) for up to one year of age and 6.60 (95% CI: 2.83-15.38) for up to two years of age, adjusted for other risk factors. During the second year of life, RSV hospitalisation continued for children with Down's, while it was minimal for the controls.

CONCLUSION

Children with Down's faced a high risk of RSV hospitalisation, which continued beyond the first year of age.

Quantitative, Phenotypical, and Functional Characterization of Cellular Immunity in Children and Adolescents With Down Syndrome

Background

Infections and autoimmune disorders are more frequent in Down syndrome, suggesting abnormality of adaptive immunity. Although the role of B cells and antibodies is well characterized, knowledge regarding T cells is limited.

Methods

Lymphocyte subpopulations of 40 children and adolescents with Down syndrome and 51 controls were quantified, and phenotype and functionality of antigen-specific effector T cells were analyzed with flow cytometry after polyclonal and pathogen-specific stimulation (with varicella-zoster virus [VZV] and cytomegalovirus [CMV]). Results were correlated with immunoglobulin (Ig) G responses.

Results

Apart from general alterations in the percentage of lymphocytes, regulatory T cells, and T-helper 1 and 17 cells, all major T-cell subpopulations showed higher expression of the inhibitory receptor PD-1. Polyclonally stimulated effector CD4+ T-cell frequencies were significantly higher in subjects with Down syndrome, whereas their inhibitory receptor expression (programmed cell death 1 [PD-1] and cytotoxic T-lymphocyte antigen 4 [CTLA-4]) was similar to that of controls and cytokine expression profiles were only marginally altered. Pathogen-specific immunity showed age-appropriate levels of endemic infection, with correlation of CMV-specific cellular and humoral immunity in all subjects. Among VZV IgG-positive individuals, a higher percentage of VZV-specific T-cell-positive subjects was seen in those with Down syndrome.

Conclusions

Despite alterations in lymphocyte subpopulations, individuals with Down syndrome can mount effector T-cell responses with similar phenotype and functionality as controls but may require higher effector T-cell frequencies to ensure pathogen control.

What people with Down Syndrome can teach us about cardiopulmonary disease

Down syndrome is the most common chromosomal abnormality among live-born infants. Through full or partial trisomy of chromosome 21, Down syndrome is associated with cognitive impairment, congenital malformations (particularly cardiovascular) and dysmorphic features. Immune disturbances in Down syndrome account for an enormous disease burden ranging from quality-of-life issues (autoimmune alopecia) to more serious health issues (autoimmune thyroiditis) and life-threatening issues (leukaemia, respiratory tract infections and pulmonary hypertension). Cardiovascular and pulmonary diseases account for ∼75% of the mortality seen in persons with Down syndrome. This review summarises the cardiovascular, respiratory and immune challenges faced by individuals with Down syndrome, and the genetic underpinnings of their pathobiology. We strongly advocate increased comparative studies of cardiopulmonary disease in persons with and without Down syndrome, as we believe these will lead to new strategies to prevent and treat diseases affecting millions of people worldwide.

Age-related alterations of the CD19 complex and memory B cells in children with Down syndrome

Children with Down syndrome (DS) have a high incidence of recurrent respiratory tract infections, leukaemia and autoimmune disorders, suggesting immune dysfunction. The present study evaluated the role of the CD19 complex and memory B cells in the pathogenesis of immunodeficiency in children with DS. The expression levels (median fluorescein intensity-MFI) of CD19, CD21 and CD81 molecules on the surface of B cells and memory B cell subsets were studied in 37 patients and 39 healthy controls. Twenty-nine of the DS group had congenital cardiac disease. The B cell count was significantly low in children with DS compared with healthy age-matched controls for all three age groups (under 2 years; 2-6 years and older than 6 years). The MFI of CD19 was reduced in all the age groups, whereas that of CD21 was increased in those older than 2 years with DS. The expression level of CD81 was significantly increased in those older than 6 years. Age-related changes were also detected in memory B cell subsets. The frequency of CD27⁺IgD⁺IgM⁺ natural effector B cells was reduced in children with DS who had needed hospitalisation admission due to infections. The observed intrinsic defects in B cells may be responsible for the increased susceptibility of children with DS to severe respiratory tract infections.

Down's syndrome is a risk factor for severe lower respiratory tract infection due to respiratory syncytial virus

AIM

Previous studies have suggested that Down's syndrome is an independent risk factor for severe respiratory infection due to respiratory syncytial virus (RSV). We compared the clinical characteristics of children with and without Down's syndrome hospitalised due to RSV.

METHODS

This retrospective cohort study compared data from hospitalisations due to RSV lower respiratory tract infections (LRTI) in children under 14 years of age with (n = 58) and without (n = 58) Down's syndrome.

RESULTS

The Down's group had longer hospital stays than the controls of six versus four days (p < 0.0001), even after adjusting for age, weeks of gestation at birth, presence of asthma, bronchopulmonary dysplasia, haemodynamically significant and nonsignificant congenital heart disease. This difference increased when only children under one year of age were analysed to 11 versus five days (p < 0.0001). Children with Down's syndrome were more likely to be admitted to intensive care unit (43.1% versus 22.4%, p = 0.017), need noninvasive mechanical ventilation (36.2% versus 13.7%, p = 0.005) and be prescribed antibiotics and steroids.

CONCLUSION

Children with Down's syndrome hospitalised due to RSV LRTI had longer hospital stays and worse clinical courses than controls, highlighting the need for RSV prophylaxis for children with Down's syndrome, especially under one year of age.

Limited Evidence on the Management of Respiratory Tract Infections in Down's Syndrome: A Systematic Review

AIMS

To systematically review the effectiveness of preventative and therapeutic interventions for respiratory tract infections (RTIs) in people with Down's syndrome.

METHODS

Databases were searched for any published and ongoing studies of respiratory tract diseases in children and adults with Down's syndrome. These databases were searched for controlled trials, cohort studies and controlled before-after studies. Trial registries were searched for ongoing studies. Initially, all study types were included to provide a broad overview of the existing evidence base. However, those with a critical risk of bias were excluded using the Cochrane Risk of Bias tool.

RESULTS

A total of 13,575 records were identified from which 5 studies fulfilled the eligibility criteria and 3 fulfilled our criteria for data extraction. One randomized controlled trial of moderate risk of bias compared zinc therapy with placebo. Outcome data were only reported for 50 (78%) children who presented with extreme symptoms; no benefit of zinc therapy was found. One non-randomized controlled trial with serious risk of bias included 26 children and compared pidotimod (an immunostimulant) with no treatment; pidotimod was associated with fewer upper RTI recurrences compared with no treatment (1.43 vs. 3.82). A prospective cohort study with moderate risk of bias compared 532 palivizumab treated children with 233 untreated children and found that children treated with palivizumab had fewer respiratory syncytial virus-related hospitalization (23 untreated and 8 treated), but the same number of overall RTI-related hospitalizations (73 untreated and 74 treated) in the first 2 years of life.

CONCLUSIONS

The evidence base for the management of RTIs in people with Down's syndrome is incomplete; current studies included children only and carry a moderate to serious risk of bias. Methodologic rigorous studies are warranted to guide clinicians in how best to prevent and treat RTIs in children with Down's syndrome.

Differential Expression of Inflammation-Related Genes in Children with Down Syndrome

OBJECTIVE

The aim of the study was to investigate the expression patterns of a specific set of genes involved in the inflammation process in children with Down Syndrome (DS) and children without the syndrome (control group) to identify differences that may be related to the immune abnormalities observed in DS individuals.

METHOD

RNA samples were obtained from peripheral blood, and gene expression was quantified using the TaqMan® Array Plate Human Inflammation Kit, which facilitated the investigation into 92 inflammation-related genes and four reference genes using real-time polymerase chain reaction (qPCR).

RESULTS

Twenty genes showed differential expression in children with DS; 12 were overexpressed (PLA2G2D, CACNA1D, ALOX12, VCAM1, ICAM1, PLCD1, ADRB1, HTR3A, PDE4C, CASP1, PLA2G5, and PLCB4), and eight were underexpressed (LTA4H, BDKRB1, ADRB2, CD40LG, ITGAM, TNFRSF1B, ITGB1, and TBXAS1). After statistically correcting for the false discovery rate, only the genes BDKRB1 and LTA4H showed differential expression, and both were underexpressed within the DS group.

CONCLUSION

DS children showed differential expression of inflammation-related genes that were not located on chromosome 21 compared with children without DS. The BDKRB1 and LTA4H genes may differentiate the case and control groups based on the inflammatory response, which plays an important role in DS pathogenesis.

Aggressive forms of periodontitis secondary to systemic disorders

A number of systemic disorders increase a patient's susceptibility to destructive periodontitis and have impacts on periodontal disease progression and severity. The underlying factors are usually genetic and are mainly related to alterations in the immune response and in certain endocrine functions, leading to various syndromes in which periodontitis and/or early tooth loss are secondary manifestations. Neutrophils are important immune defense cells that play a significant role in controlling the spread of microbial plaque infections in the dentogingival region. This review focuses on a selected group of systemic disorders that are associated with alterations in either neutrophil counts (quantitative disorders) or function (qualitative disorders), and defects in the mineralization of bone and dental tissues. In most of these diseases controlling the periodontal disease progression is very challenging. Proper diagnosis is a prerequisite for proper management of the periodontal problem. Future advances in research, including gene targeting and the resolution of enzyme deficiencies, may bring about remedies of the underlying systemic disorders and may significantly improve the outcome of periodontal treatment in these patients.

Emphasizing the health benefits of vitamin D for those with neurodevelopmental disorders and intellectual disabilities

People with neurodevelopmental disorders and intellectual disabilities have much greater health care needs. Mainly staying indoors, such people generally have low 25-hydroxyvitamin D (25(OH)D) concentrations. The Vitamin D Task Force of the American Academy of Developmental Medicine and Dentistry (AADMD) reviewed the evidence of 25(OH)D concentrations that benefit the health of persons with developmental disabilities. Maintaining recommended optimal serum 25(OH)D concentrations year long will benefit skeletal development in infants, children, and adolescents, and benefit musculoskeletal health and neuromuscular coordination in adult patients, and decrease risk of falls. Maintaining optimal concentrations decreases risks and severities of autoimmune diseases, cardiovascular disease, many types of cancer, dementia, types 1 and 2 diabetes mellitus, and respiratory tract infections. Other benefits include improved dental and oral health and improved physical performance. The Task Force recommends that 25(OH)D concentrations for optimal health to be in the range of 75 to 125 nmol/L, which can be achieved using between 800 and 4000 IU/day vitamin D3 and sensible exposure to solar UVB radiation. The paper also discusses the potential risks of higher 25(OH)D concentrations, the evidence from and limitations of randomized controlled trials, and the recommendations by various groups and agencies.