A link between parotid salivary Ig level and recurrent respiratory infections in young Down's syndrome patients

Increased levels of anti-BSA antibodies in children with Down syndrome

INTRODUCTION

Autoimmune diabetes occurs more often in the first 2 years of life in children with Down syndrome (DS) compared with the general population. We previously observed increased frequencies of islet autoantibodies, including insulin autoantibodies (IAA), in children with DS. Assays for IAA using ¹²⁵I-labelled insulin require competition to overcome cross reactivity with antibodies to the cow's milk protein, bovine serum albumin (BSA). ¹²⁵I-IAA assay results suggested that levels of antibodies to BSA may also be increased in children with DS. The aim of this study therefore was to determine whether the levels of anti-BSA antibodies differed in children with DS compared with controls.

METHODS

Samples were available from two populations with DS: one from the UK, (UK DS cohort n=106, 58 male, median age 12.5 years) and one from Estonia (Estonian DS cohort: n=121, 65 male, median age 9.75 years). A UK control population was provided by sex and age-matched healthy siblings of probands participating in the Bart's Oxford (BOX) family study of type 1 diabetes. A competitive-displacement radiobinding assay (RBA) and a Dissociation Enhanced Lanthanide Fluoroimmunoassay (DELFIA) were developed to measure and confirm anti-BSA antibody levels. HLA class II genotype was analysed by PCR using sequence specific primers (PCR-SSP).

RESULTS

Overall, levels of anti-BSA antibodies were increased in those with DS compared with controls (p<0.0001) but this was not HLA associated.

CONCLUSION

Increased levels of anti-BSA antibodies may reflect a defect in immune maturation or increased gut permeability in children with DS, increasing their risk of developing autoimmunity.

Resistance training and Down Syndrome: A narrative review on considerations for exercise prescription and safety

The current manuscript reviews the literature on the health effects of resistance training (RT) for individuals with Down syndrome (DS), focusing on this training modality’s methodology, application, and safety. The literature has mentioned that early aging in this population is associated with loss of muscle strength, lower lean and bone mass, and increased obesity. It is necessary to propose non-pharmacological measures for prevention and health promotion. Thus, this review suggests a current research-based RT guide for individuals with DS. This review is divided into three sections: Section 2 briefly reviews DS and the effects on structural and functional decline and how exercise and physical activity can influence health aspects in this population; Section 3 summarizes the evidence for RT prescription; Section 4 briefly reviews the health and potential benefits of RT in individuals with DS. The findings from this review suggest that most individuals with DS should engage in moderate-intensity RT at least 2 days a week and perform RT on the major muscle groups and include balance training. The RT program should be modified and adapted according to individuals’ characteristics and limitations. RT promotes positive, health-related benefits such as increasing strength, improving body composition, improving functional capacity and balance, reducing inflammatory status and oxidative stress, and improving the immune system. The RT protocols summarized in this current review provide guidance, critical conclusions, and novel research settings, which could be useful to coaches, clinicians, and researchers to effectively design RT program for individuals with DS.

Prevalence of saliva immunoglobulin A antibodies reactive with severe acute respiratory syndrome coronavirus 2 among Japanese people unexposed to the virus

While the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a threat to public health as the number of cases and COVID-19-related deaths are increasing worldwide, the incidence of the virus infection is extremely low in Japan compared with many other countries. To explain this uncommon phenomenon, we investigated the prevalence of naturally occurring ("natural") antibodies, focusing on those of the secretory immunoglobulin A (sIgA) form, reactive with SARS-CoV-2 among Japanese people. One hundred and eighty healthy Japanese volunteers of a wide range of age who had been considered to be unexposed to SARS-CoV-2 participated in this study. Saliva samples and blood samples were collected from all of the 180 participants and 139 adults (aged ≥ 20 years) included therein, respectively. The determination of saliva IgA antibodies, mostly comprising sIgA antibodies, as well as serum IgA and immunoglobulin G antibodies, reactive with the receptor binding domain of the SARS-CoV-2 spike-1 subunit proteins was conducted using an enzyme-linked immunosorbent assay. The major findings were that 52.78% (95% confidence interval, 45.21%-60.25%) of the individuals who had not been exposed to SARS-CoV-2 were positive for saliva IgA antibodies with a wide range of levels between 0.002 and 3.272 ng/mL, and that there may be a negative trend in positivity for the antibodies according to age. As we had expected, a frequent occurrence of assumable "natural" sIgA antibodies reactive with SARS-CoV-2 among the studied Japanese participant population was observed.

Lung disease manifestations in Down syndrome

Down syndrome (DS) is one of the most prevalent chromosomal abnormalities worldwide, affecting 1 in 700 live births. Although multiple organ systems are affected by the chromosomal defects, respiratory failure and lung disease are the leading causes of morbidity and mortality observed in DS. Manifestations of DS in the respiratory system encompass the entire lung starting from the nasopharynx to the trachea/upper airways to the lower airways and alveolar spaces, as well as vascular and lymphatic defects. Most of our knowledge on respiratory illness in persons with DS arises from pediatric studies; however, many of these disorders present early in infancy, supporting developmental mechanisms. In this review, we will focus on the different lung phenotypes in DS, as well as the genetic and molecular pathways that may be contributing to these complications during development.

Prescription and Effects of Strength Training in Individuals with Intellectual Disability-A Systematic Review

The practice of physical exercise (PE), especially strength training (ST), has health benefits in the healthy population; however, the literature is scarce in the recommendations related to the population with intellectual disability (ID). This study represents the first analysis on the topic and aims to examine the structure and efficacy of ST experimental intervention programs in individuals with ID. This systematic review was carried out between January and April 2021, using the PubMed, Web of Science, Scopus, and SPORTDiscus databases, according to the PRISMA guidelines. From a total of 166 studies, eight were included in the present systematic review. The studies included a total of 280 individuals (18.23 ± 2.86 years old). The main features of the exercise programs are: 12 weeks average duration, three weekly sessions of 45–60 min, six to seven exercises targeting the main muscle groups, two to three sets, 6–12 repetitions, and avoiding free weights for safety reasons. The main results showed increments in strength, balance and fat-free mass and decrements in fat mass and waist circumference. It is a useful guideline for PE technicians to prescribe and adjust correctly in order to not only promote physical fitness, but improve the quality of life of individuals with ID.

Pulmonary hypertension and myocardial function in infants and children with Down syndrome

Down Syndrome (DS) is the most common chromosomal abnormality of live born babies. Individuals with DS are at increased risk of cardiopulmonary morbidities in the early neonatal period, infancy and childhood that manifest with elevated pulmonary arterial pressures and altered myocardial performance. Pulmonary hypertension (PH) during the early neonatal period remains under-recognised in this population. PH may occur with or without a congenital heart defect in children with DS and is more common than in the general population. Early detection and continued screening of PH throughout infancy and childhood for these at-risk children is crucial for prompt intervention and potential prevention of long-term sequelae on cardiac function. This review summarises the main physiological concepts behind the mechanisms of PH in children with DS and provides a summary of the current available literature on PH and its impact on myocardial performance.

Salivary anti-SARS-CoV-2 IgA as an accessible biomarker of mucosal immunity against COVID-19

Background

Mucosal immunity, including secretory IgA (sIgA), plays an important role in early defenses against respiratory pathogens. Salivary testing, the most convenient way to measure sIgA, has been used to characterize mucosal immune responses to many viral infections including SARS, MERS, influenza, HIV, and RSV. However, its role has not yet been characterized in the COVID-19 pandemic. Here, we report development and validation of a rapid immunoassay for measuring salivary IgA against the SARS-CoV-2 virus, and report quantitative results in both pre-COVID-19 and muco-converted subjects.

Methods

We developed and refined a specific test for salivary IgA against SARS-CoV-2 on the Brevitest platform, a rapid immunoassay system designed for point-of-care use. A qualitative test was validated as per FDA guidelines with saliva obtained from subjects prior to the emergence of COVID-19, and from PCR-confirmed COVID-19 patients. We also generated a quantitative measure of anti-SARS-CoV-2 salivary IgA. Time taken for saliva self-collection was measured and its ease-of-use assessed.

Results

We successfully validated a qualitative salivary assay for SARS-CoV-2 IgA antibodies, with positive and negative predictive values of 92% and 97%, respectively, and no observable cross-reactivity with any of seven potential confounders. Pre-COVID-19 saliva samples showed an 8-fold range of IgA concentrations, suggesting a broad continuum of natural antibody resistance against the novel virus, though at levels lower than that observed in COVID-19 PCR-confirmed subjects. Samples from muco-positive subjects also shown a ~9-fold variation in salivary IgA levels, with elevated salivary IgA observed beyond three months after onset of symptoms. We observed a correlation (r=0.4405) between salivary IgA levels and COVID-19 disease severity. In anecdotal observations, we observed individuals who exhibited antibodies early in the course of their disease, contemporaneously with a positive PCR test, as well as individuals who muco-converted despite no known direct exposure to a COVID-19 patient, no symptoms, and negative molecular and/or serum antibody tests. Salivary collection took 5-10 minutes, and was reported as being easy (mean of 1.1 on a scale of 1 to 10).

Implications

Mucosal immunity, including secretory IgA, plays an important role in host defense against respiratory pathogens, and our early data suggest it may do so in COVID-19. Salivary IgA, an accessible marker of mucosal immunity, may be a useful indicator of several key parameters including individual and community immune response, disease severity, clinical risk, and herd immunity. The non-invasive nature and ease of saliva collection facilitates its potential use as a biomarker for ongoing patient assessment and management, as well as a community surveillance tool. By measuring mucosal immune responses directly and systemic immune responses indirectly, salivary IgA could be useful in developing and deploying a vaccine(s) against COVID-19. Quantitative IgA assessment could also potentially serve as a tool to segment the population into different risk categories and inform individual and collective decisions relating to appropriate activities and vaccine prioritization/delivery. These data reinforce the importance of further investigation into the role of mucosal immunity and IgA in host responses against COVID-19.

Salivary testosterone and immunoglobulin A were increased by resistance training in adults with Down syndrome

This study was designed to assess the influence of resistance training on salivary immunoglobulin A (IgA) levels and hormone profile in sedentary adults with Down syndrome (DS). A total of 40 male adults with DS were recruited for the trial through different community support groups for people with intellectual disabilities. All participants had medical approval for participation in physical activity. Twenty-four adults were randomly assigned to perform resistance training in a circuit with six stations, 3 days per week for 12 weeks. Training intensity was based on functioning in the eight-repetition maximum (8RM) test for each exercise. The control group included 16 age-, gender-, and BMI-matched adults with DS. Salivary IgA, testosterone, and cortisol levels were measured by ELISA. Work task performance was assessed using the repetitive weighted-box-stacking test. Resistance training significantly increased salivary IgA concentration (P=0.0120; d=0.94) and testosterone levels (P=0.0088; d=1.57) in the exercising group. Furthermore, it also improved work task performance. No changes were seen in the controls who had not exercised. In conclusion, a short-term resistance training protocol improved mucosal immunity response as well as salivary testosterone levels in sedentary adults with DS.

Significant impact of recurrent respiratory tract infections in children with Down syndrome

OBJECTIVE

Parents and health professionals believe that recurrent respiratory tract infections (RRTI) have a large impact on children with Down syndrome (DS). We studied the relation between parent-reported RRTI and development, behaviour and health-related quality of life (HRQoL) in 8-year-old children with DS.

METHOD

During a 3-year period, 325 children with DS were recruited for inclusion in this observational study. Parents were asked to fill in the Child Behavior Checklist and TNO-AZL Children's Quality of Life Parent Form. A psychological assistant administrated the McCarthy Scales of Children's Abilities. The children were divided into a group with presence of RRTI (RRTI (+) ) and a group without RRTI (RRTI (-) ), on the basis of parental report. Linear regression analyses were performed to assess the effect of RRTI, while correcting for the influence of confounders.

RESULTS

Compared with RRTI (-) children (n = 176), RRTI (+) children (n = 149, 46%) showed decreased mental and motor development (mean developmental age 3.67 vs. 4.08 years), more behavioural problems and lower scores on most HRQoL scales (P < 0.05). Moreover, school enrolment is less favourable in RRTI (+) children.

CONCLUSION

In 8-year-olds with DS, the children with parent-reported RRTI show more delayed development, more behavioural problems and lower HRQoL compared with the children without RRTI. Although this association does not prove a causal relationship, further studies should focus on this, because RRTI are potentially preventable.

Host defenses

Repeated episodes of viral upper respiratory tract infections occur anywhere from four to eight times per year in healthy individuals Local and systemic defense mechanisms exist to battle respiratory tract pathogens. Clinical manifestations are mainly due to host inflammatory response. Unfortunately, the host defense mechanisms are very often not sufficient to prevent subsequent/repeated episodes of infections(s). Further insight into the interaction of infectious agent and host immune response, genetic factors, and environmental factors is needed for a better understanding of why humans repeatedly and frequently suffer from infections with respiratory agents and develop a disease syndrome known as common cold.

Salivary LL-37 secretion in individuals with Down syndrome is normal

Antimicrobial peptides play an important role in the innate immune response. Deficiency in salivary LL-37 antimicrobial peptide has been implicated in periodontitis in patients with morbus Kostman syndrome. Down syndrome is associated with periodontitis, diminished salivary flow, and salivary immunoglobulin deficiency. In the present study, levels of LL-37 and its hCAP18 precursor were measured in saliva samples from young individuals with Down syndrome and compared with levels in those from age-matched healthy controls. LL-37 and human cathelicidin antimicrobial protein (hCAP18) were detected in whole but not in parotid saliva. hCAP18 was more abundant than LL-37. The concentrations of salivary hCAP18 and LL-37 were found to be higher in individuals with Down syndrome than in healthy controls, but their secretion rates were similar. We concluded that, while the adaptive immunity of individuals with Down syndrome is impaired at the oral mucosa, the secretion rate of the LL-37 component of the innate immune system is normal.

The Role of Mucosal Immunity: An Update

There is considerable evidence that the mucosa associated lymphoid tissues (MALT) of the body play an active part in triggering off and conducting the immune system's response to both viral and bacterial pathogens. Effectors are capable of intercepting the micro-organisms and rendering them harmless before they penetrate through the mucous membranes, or of expelling and inactivating them after they have penetrated. The system is consequently useful both in the prevention of infection and in the humoral or cellulo-mediated immune response. These operations, whose principal protagonists are Immunoglobulins A and dendritic cells, are made possible by the high degree of functional interconnection which binds the effectors of the system and the anatomical structures located in the mucosae. The data provided in literature consequently infer that appropriate stimulation of mucosal immunity, which takes into account the new acquisitions in the field of immunology, can enable oral vaccination to overcome the obstacles encountered up till now in terms of insufficient protection against diseases.