Age-dependent deficiency in saliva and salivary antibodies secretion in Down's syndrome

The immune system in Down Syndrome: Autoimmunity and severe infections

Over 200,000 individuals in the United States alone live with Down Syndrome (DS), the most common genetic disorder associated with intellectual disability. DS has a constellation of features across the body, including dysregulation of the immune system. Individuals with DS have both a higher frequency of autoimmunity and more severe infections than the general population, highlighting the importance of understanding the immune system in this population. Individuals with DS present with dysregulation of both the innate and adaptive immune systems. Elevated cytokine levels, increased type I and type II IFN signaling, a shift toward memory phenotypes in T cells, and a decrease in the size of the B-cell compartment are observed in individuals with DS, which contribute to both autoinflammation and severe infections. Herein, we discuss the current knowledge of the immune system in individuals with Down Syndrome as well as ideas of necessary further investigations to decipher the mechanisms by which trisomy 21 leads to immune dysregulation, with the ultimate goal of identifying clinical targets to improve treatment.

The Clinical and Neuropathological Features of Sporadic (Late-Onset) and Genetic Forms of Alzheimer's Disease

The purpose of this review is to compare and highlight the clinical and pathological aspects of genetic versus acquired Alzheimer's disease: Down syndrome-associated Alzheimer's disease in (DSAD) and Autosomal Dominant Alzheimer's disease (ADAD) are compared with the late-onset form of the disease (LOAD). DSAD and ADAD present in a younger population and are more likely to manifest with non-amnestic (such as dysexecutive function features) in the prodromal phase or neurological features (such as seizures and paralysis) especially in ADAD. The very large variety of mutations associated with ADAD explains the wider range of phenotypes. In the LOAD, age-associated comorbidities explain many of the phenotypic differences.

Association between Antimicrobial Peptide Histatin 5 Levels and Prevalence of Candida in Saliva of Patients with Down Syndrome

There are no studies on Candida colonization and micropeptides of saliva in any patient. Therefore, we studied the effects of the salivary antimicrobial peptide histatin 5 on oral fungal colonization; subjects were subdivided into Down syndrome (D) and normal (N) groups by age: N-1 and D-1, age <20 years; N-2 and D-2, age >40 years. Histatin 5 concentration in saliva was measured by enzyme-linked immunosorbent assay. Oral Candida species were identified using CHROMagar Candida. Candida colonization was significantly enhanced in the D-1 and D-2 groups compared to the N-1 and N-2 groups. There was no predominant difference in salivary histatin 5 concentration between the D-1 and N-1 groups, but it was significantly lower in the D-2 group than in the N-2 group. Only in the N-2 group was there a correlation between the concentration of histatin 5 and total protein, while no correlation was found in the other groups. In elderly patients with Down syndrome, the decrease in histatin 5 shown in this study may lead to oral Candida colony formation. Therefore, the results of this study suggest that a deficiency of the antimicrobial peptide histatin 5 could possibly induce oral Candida infection in DS.

Salivary IgA as a Useful Biomarker for Dental Caries in Down's Syndrome Patients: A Systematic Review and Meta-analysis

The objective of this systematic review and meta-analysis is to critically analyze and summarize studies reporting association of salivary immunoglobulin A (IgA) levels as a biomarker for dental caries in Down syndrome (DS) patients. Using the keywords salivary [All Fields] AND IgA [All Fields] AND ("down syndrome" [MeSH Terms] OR ("down"[All Fields] AND "syndrome" [All Fields]) OR "down syndrome" [All Fields]), an electronic search was conducted via PubMed and Scopus databases by two authors, H. H. and Z. K. independently. Retrieved studies were screened against the predefined exclusion and inclusion criteria. To estimate the risk of bias, quality assessment of included studies was carried using the Newcastle-Ottawa quality assessment scale for observational studies. Primary search resulted in 10 articles from PubMed and 13 articles from Scopus. Ten studies fulfilled the defined selection criteria and evaluated the salivary IgA (sIgA) level in DS patients with dental caries. Five articles were further analyzed in a quantitative synthesis presented in the meta-analysis. Due to a modified lifestyle and compromised oral hygiene in DS patients, understandably, it is still postulated in the literature that the presence of sIgA can have a protective effect on the occurrence of dental caries as compared with healthy counterparts. As indicated by the present meta-analysis, no conclusions can be drawn as to definitively label sIgA as a biomarker for dental caries. Further, well-designed longitudinal clinical studies and translational research are therefore required before the benchmarking of sIgA as a useful biomarker for dental caries in DS patients with preferable molecular insights.

Risk factors and intraoral breast milk application for methicillin-resistant Staphylococcus aureus colonization in surgical neonates

BACKGROUND

Our previous study identified methicillin-resistant Staphylococcus aureus (MRSA) colonization as an independent risk factor for neonatal surgical site infection. Here we introduce intraoral breast milk application (IBMA) during a fasting state to prevent MRSA colonization. We aimed to evaluate both the risk factors for MRSA colonization and the efficacy of IBMA in neonatal surgical patients.

METHODS

A retrospective review was performed using admission data from 2007 to 2016. Neonatal patients who underwent surgery and were tested periodically for MRSA colonization were evaluated for an association between MRSA colonization and perinatal or perioperative factors.

RESULTS

The overall incidence of MRSA colonization for the 159 patients enrolled in this study was 16.4%. Univariate analysis showed that MRSA colonization was significantly more frequent in the following patients: those with Down syndrome, those admitted on their day of birth, those in need of fasting immediately after birth, and those not receiving IBMA. Multivariate analysis showed that comorbid Down syndrome was an independent risk factor (hazard ratio: 4.6; 95% confidence interval: 1.2-19.5, P = 0.03) and implementation of IBMA was an independent preventive factor for MRSA colonization (hazard ratio: 0.4; 95% confidence interval: 0.1-0.9, P = 0.04). MRSA-positive patients admitted significantly earlier and stayed longer preoperatively than MRSA-negative patients.

CONCLUSIONS

In neonates undergoing surgery, and patients with Down syndrome, early diagnosis after birth and a long waiting period before operation may be associated with MRSA colonization. Intraoral breast milk application may be beneficial for preventing MRSA colonization.

Salivary secretory IgA concentration and dental caries in children with Down syndrome

PURPOSE

To evaluate the relationship between salivary secretory immunoglobulin A (sIgA) concentration and dental caries in children with Down syndrome (DS) and compare it with findings in non-DS children.

METHODS

The sample comprised 61 DS children and 52 non-DS children, aged 6 to 14 years. Caries experience, plaque index (PI), and gingival bleeding index (GBI) were recorded. Saliva samples were collected from all children. Total salivary sIgA concentrations were determined using an enzymatic assay method.

RESULTS

Caries experience in primary and permanent dentitions were similar in DS and non-DS children. However, PI and GBI values were significantly lower in DS compared to non-DS children. DS children had higher salivary sIgA concentrations compared to non-DS children. No difference in sIgA concentration was observed between children with and without caries experience in either group.

CONCLUSIONS

DS children have higher salivary sIgA concentrations than non-DS children. However, this finding did not correlate with caries experience in the study population.

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.

Oral transmucosal drug delivery for pediatric use

The formulation of medicines for children remains a challenge. An ideal pediatric formulation must allow accurate dose administration and be in a dosage form that can be handled by the target age group. It is also important to consider the choices and the amount of excipients used in the formulation for this vulnerable age group. Although oral formulations are generally acceptable to most pediatric patients, they are not suitable for drugs with poor oral bioavailability or when a rapid clinical effect is required. In recent years, oral transmucosal delivery has emerged as an attractive route of administration for pediatric patients. With this route of administration, a drug is absorbed through the oral mucosa, therefore bypassing hepatic first pass metabolism and thus avoiding drug degradation or metabolism in the gastrointestinal tract. The high blood flow and relatively high permeability of the oral mucosa allow a quick onset of action to be achieved. It is a simple and non-invasive route of drug administration. However, there are several barriers that need to be overcome in the development of oral transmucosal products. This article aims to provide a comprehensive review of the current development of oral transmucosal delivery specifically for the pediatric population in order to achieve systemic drug delivery. The anatomical and physiological properties of the oral mucosa of infants and young children are carefully examined. The different dosage forms and formulation strategies that are suitable for young patients are discussed.

How I treat ALL in Down's syndrome: pathobiology and management

Children with Down syndrome are at high risk for developing B-cell precursor acute lymphoblastic leukemia (DS-ALL) associated with poor outcome due to both a high relapse rate and increased treatment-related mortality (TRM) from infections. Biologically, these heterogeneous leukemias are characterized by under-representation of the common cytogenetic subgroups of childhood ALL and overrepresentation of CRLF2-IL7R-JAK-STAT activating genetic aberrations. Although relapse is the major determinant of poor outcomes in this population, de-escalation of chemotherapy intensity might be feasible in the 10% to 15% DS-ALL patients with ETV6-RUNX1 or high hyperdipoidy in whom TRM is the major limiting event. As infection-associated TRM occurs during all treatment phases, including the maintenance period, increased surveillance and supportive care is required throughout therapy. Improvement in outcome will require better understanding of the causes of treatment failure and TRM, incorporation of new therapies targeting the unique biological properties of DS-ALL, and enhanced supportive care measures to reduce the risk of infection-related TRM. To facilitate these goals, an international collaboration plans to establish a prospective DS-ALL registry and develop specific supportive care recommendations for this at-risk population.

Acute lymphoblastic leukemia in children with Down syndrome: a retrospective analysis from the Ponte di Legno study group

Children with Down syndrome (DS) have an increased risk of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). The prognostic factors and outcome of DS-ALL patients treated in contemporary protocols are uncertain. We studied 653 DS-ALL patients enrolled in 16 international trials from 1995 to 2004. Non-DS BCP-ALL patients from the Dutch Child Oncology Group and Berlin-Frankfurt-Münster were reference cohorts. DS-ALL patients had a higher 8-year cumulative incidence of relapse (26% ± 2% vs 15% ± 1%, P < .001) and 2-year treatment-related mortality (TRM) (7% ± 1% vs 2.0% ± <1%, P < .0001) than non-DS patients, resulting in lower 8-year event-free survival (EFS) (64% ± 2% vs 81% ± 2%, P < .0001) and overall survival (74% ± 2% vs 89% ± 1%, P < .0001). Independent favorable prognostic factors include age <6 years (hazard ratio [HR] = 0.58, P = .002), white blood cell (WBC) count <10 × 10(9)/L (HR = 0.60, P = .005), and ETV6-RUNX1 (HR = 0.14, P = .006) for EFS and age (HR = 0.48, P < .001), ETV6-RUNX1 (HR = 0.1, P = .016) and high hyperdiploidy (HeH) (HR = 0.29, P = .04) for relapse-free survival. TRM was the major cause of death in ETV6-RUNX1 and HeH DS-ALLs. Thus, while relapse is the main contributor to poorer survival in DS-ALL, infection-associated TRM was increased in all protocol elements, unrelated to treatment phase or regimen. Future strategies to improve outcome in DS-ALL should include improved supportive care throughout therapy and reduction of therapy in newly identified good-prognosis subgroups.

Reduced salivary flow and colonization by mutans streptococci in children with Down syndrome

OBJECTIVES

Although individuals with Down syndrome have considerable oral disease, the prevalence of dental caries in this group is low. The present study aimed to compare known risk factors for dental caries development in children with Down syndrome and a matched population (siblings). In both populations, the number of acidogenic microorganisms, such as mutans streptococci, lactobacilli and Candida species, and the paraffin-stimulated pH, flow rate and IgA concentration in whole saliva were evaluated and compared.

METHOD

Saliva was collected, and the caries index was evaluated in 45 sibling pairs aged between 6 and 18 years old. The salivary IgA concentration was determined by immunoturbidimetry. Salivary mutans streptococci, lactobacilli and Candida species were quantified on mitis salivarius agar containing bacitracin and 20% sucrose, rogosa agar supplemented with glacial acetic acid and sabouraud agar supplemented with chloramphenicol, respectively.

RESULTS

Down syndrome children had a higher caries-free rate (p<0.05) and lower salivary mutans streptococci counts (p<0.03) compared to their siblings. Similar numbers of lactobacilli and Candida species were found in both groups. Salivary flow rates were 36% lower in Down syndrome children compared to their siblings (p<0.05). The salivary pH did not differ between Down syndrome children and controls. The Down syndrome children had an IgA secretion rate 29% lower than that of their siblings, but this difference was not statistically significant.

CONCLUSIONS

In conclusion, the lower number of mutans streptococci in the saliva may be one of the factors contributing to the lower caries rate observed in Down syndrome children, despite evidence of hyposalivation.

Association of interleukin-1 polymorphisms with periodontitis in Down syndrome

This study examined the association of IL1 genetic polymorphisms (IL-1A +4845, IL-1B +3954 & IL-1RN +2018) with periodontal disease status of Down syndrome (DS) individuals. Fifty-four DS patients (18-56 yr, 48.15% male, 77.78% Caucasians) were recruited from the Georgia Regional Hospital (GRH) health care system. Two comparable groups (71 mentally retarded patients and 87 control subjects) were also recruited. All subjects were nonsmokers. Periodontal evaluations (plaque index, gingival index, bleeding-on probing and clinical attachment levels (AL)), personal and professional dental care habits were recorded. Blood was collected by a venipuncture. The IL-1A +4845, IL-1B +3954 & IL-1RN +2018 loci were genotyped by the TaqMan assay. No statistically significant differences were noted in the distribution of IL-1 gene polymorphisms between the three groups. The IL-1 variant genotypes varied by race; for both IL-1A and IL-1RN, the variant gene was significantly more prevalent among whites than non-whites (ps > 0.1). ANCOVA, which also adjusted for age, showed a 3-way interaction among dental visits, gene variation and Down status [(F(1, 179) = 3.96, P = 0.048 in White subjects and F(1, 241) = 2.96, P = 0.087 in all subjects). Post-hoc t-tests confirmed lower levels of AL in IL-1RN-variant Down subjects receiving more frequent dental visits (P < 0.05). ANCOVA, which also adjusted for age, showed an interaction between IL-1A/B gene variation and Down status (F(1, 174) = 3.04, P = 0.083 in White subjects and F(1, 235) = 3.72, P = 0.055 in all subjects). Post-hoc t-tests confirmed lower levels of AL in IL-1A/B-variant Down subjects (P < 0.05). The distribution of variant IL-1 genes in DS subjects was not different from the general population. However the association between the carriage of the IL-1 rare alleles and periodontitis differed between the Down and non-Down subjects. The carriage of the IL-1 rare alleles in the Down subjects tended to confer a protective effect against loss of periodontal attachment.

Infections and immunodeficiency in Down syndrome

Down syndrome (DS) is the most common genetic disease and presents with cognitive impairment, cardiac and gastrointestinal abnormalities, in addition to other miscellaneous clinical conditions. DS individuals may have a high frequency of infections, usually of the upper respiratory tract, characterized by increased severity and prolonged course of disease, which are partially attributed to defects of the immune system. The abnormalities of the immune system associated with DS include: mild to moderate T and B cell lymphopenia, with marked decrease of naive lymphocytes, impaired mitogen-induced T cell proliferation, reduced specific antibody responses to immunizations and defects of neutrophil chemotaxis. Limited evidence of genetic abnormalities secondary to trisomy of chromosome 21 and affecting the immune system is available, such as the potential consequences of gene over-expression, most significantly SOD1 and RCAN1. Secondary immunodeficiency due to metabolic or nutritional factors in DS, particularly zinc deficiency, has been postulated. Non-immunological factors, including abnormal anatomical structures (e.g. small ear canal, tracheomalacia) and gastro-oesophageal reflux, may play a role in the increased frequency of respiratory tract infections. The molecular mechanisms leading to the immune defects observed in DS individuals and the contribution of these immunological abnormalities to the increased risk of infections require further investigation. Addressing immunological and non-immunological factors involved in the pathogenesis of infectious diseases may reduce the susceptibility to infections in DS subjects.

A comparison of the sialochemistry, oral pH, and oral health status of Down syndrome children to healthy children

BACKGROUND

The aetiology of low caries incidence in Down syndrome (DS) children is not entirely clear. Aim. To compare sialochemistry and oral mucosal pH between Down syndrome children with caries (DS-Ca) and caries free (DS-CaF), and healthy children with caries (C-Ca) and caries free (C-CaF).

DESIGN

The study group comprised 70 children with DS (mean age 4.41 +/- 1.9 years); 32 healthy children (mean age 9.22 +/- 2.7 years) served as control. Groups were further subdivided according to caries status: DS-Ca, DS-CaF, C-Ca and C-CaF. Sialochemistry analysis included calcium (Ca), sodium (Na), potassium (K), and chloride (Cl). Mucosal pH, plaque and gingival indices (PI and GI), and caries status were recorded.

RESULTS

DMFT/dmft were significantly lower in the DS group. Cl and Ca levels were significantly higher in the DS-Ca compared to the C-Ca and the C-CaF children. Na and K were significantly higher in DS-Ca group compared to DS-CaF group. PI and GI were significantly higher in DS-C children compared to DS-CaF children.

CONCLUSIONS

DS may manifest itself in the salivary glands. Consequently, different electrolyte salivary environment may form, leading to lower caries rates among DS children.