Aberrations in circulating inflammatory cytokine levels in patients with Down syndrome: a meta-analysis

Intricacies of aging and Down syndrome

Down syndrome is the most frequently occurring genetic condition, with a substantial escalation in risk associated with advanced maternal age. The syndrome is characterized by a diverse range of phenotypes, affecting to some extent all levels of organization, and its progeroid nature - early manifestation of aspects of the senile phenotype. Despite extensive investigations, many aspects and mechanisms of the disease remain unexplored. The current review aims to provide an overview of the main causes and manifestations of Down syndrome, while also examining the phenomenon of accelerated aging and exploring potential therapeutic strategies.

JAK inhibition decreases the autoimmune burden in Down syndrome

Individuals with Down syndrome (DS), the genetic condition caused by trisomy 21 (T21), display clear signs of immune dysregulation, including high rates of autoimmune disorders and severe complications from infections. Although it is well established that T21 causes increased interferon responses and JAK/STAT signaling, elevated autoantibodies, global immune remodeling, and hypercytokinemia, the interplay between these processes, the clinical manifestations of DS, and potential therapeutic interventions remain ill defined. Here, we report a comprehensive analysis of immune dysregulation at the clinical, cellular, and molecular level in hundreds of individuals with DS. We demonstrate multi-organ autoimmunity of pediatric onset concurrent with unexpected autoantibody-phenotype associations. Importantly, constitutive immune remodeling and hypercytokinemia occur from an early age prior to autoimmune diagnoses or autoantibody production. We then report the interim analysis of a Phase II clinical trial investigating the safety and efficacy of the JAK inhibitor tofacitinib through multiple clinical and molecular endpoints. Analysis of the first 10 participants to complete the 16-week study shows a good safety profile and no serious adverse events. Treatment reduced skin pathology in alopecia areata, psoriasis, and atopic dermatitis, while decreasing interferon scores, cytokine scores, and levels of pathogenic autoantibodies without overt immune suppression. Additional research is needed to define the effects of JAK inhibition on the broader developmental and clinical hallmarks of DS. ClinicalTrials.gov identifier: NCT04246372.

Dysregulation of the Immune System in a Natural History Study of 1299 Individuals with Down Syndrome

Dysregulation of the immune system in individuals with Down syndrome is thought to play a major role in the pathophysiology of many clinical presentations. This natural history of disease study took a comprehensive evaluation of the prevalence of different immune related diagnoses in a cohort of 1299 patients with Down syndrome compared to a 2605 patient control cohort at the Mount Sinai Health System in New York, NY over the past 18 years. We conducted a stepwise analysis of the odds of receiving a diagnosis at the Chapter, Sub-chapter and Diagnosis level of the ICD-CM-10 code system. Individuals in our Down syndrome cohort had higher odds of a diagnosis with inflammatory and autoimmune presentations such as Alopecia areata (OR 6.06, p = 0.01), Other sepsis (OR 4.79, p < 0.001, Purpura and other hemorrhagic conditions (OR 2.31, p < 0.001), and Rosacea (OR 3.11, p < 0.001). They also presented with lower odds of a diagnosis of Herpesviral infection (OR 0.42, p = 0.01), and Viral warts (OR 0.51, p = 0.04). We posit that dysregulation of the immune system in individuals with Down syndrome has impact on infectious diseases, including lowering the incidence of viral disease and increasing its severity. Our data also suggests inflammation and autoimmune mediated diseases, in particular of the skin, are exacerbated in individuals with Down syndrome. Finally, there may be a need for greater clinical attention to non-emergent conditions within the Down syndrome patient population as those can also greatly affect quality of life.

Cytokine Storm Syndrome Responsive to IL-1 Inhibition in Trisomy 21

Background

Cytokine storm syndromes (CSS) are life-threatening systemic inflammatory disorders caused by immune system dysregulation. They can lead to organ failure and are triggered by various factors, including infections, malignancy, inborn errors of immunity, and autoimmune conditions. Trisomy 21 (TS21), also known as Down syndrome, is a genetic disorder associated with immune dysfunction, increased infection susceptibility, and inflammation. While TS21 has been linked to infectious-triggered hyperinflammation, its role as a primary cause of CSS has not been confirmed. Case Presentation. We present a case of a 16-year-old male with TS21 with fever, rash, joint pain, and abdominal symptoms. Extensive investigations ruled out infections, autoimmune conditions, malignancies, and inborn errors of immunity as triggers for a CSS. The patient's symptoms improved with treatment using IL-1 inhibition and corticosteroids.

Conclusions

This case reinforces that TS21 is an immune dysregulation disorder and highlights the importance of considering CSS in TS21 patients, even when triggers are unclear. The positive response to IL-1 inhibition in this patient suggests that dysregulation of the IL-1 superfamily and the NLRP3 inflammasome may contribute to CSS in TS21. This finding raises the possibility of using IL-1 inhibition as a treatment approach for CSS in TS21 patients.

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.

Characterization of autoimmune eye disease in association with Down's syndrome

BACKGROUND

Autoimmunity and deficiency of the transcription factor autoimmune regulator protein (AIRE) are known associations with Down syndrome (DS). Lack of AIRE abrogates thymic tolerance. The autoimmune eye disease associated with DS has not been characterized. We identified a series of subjects with DS (n = 8) and uveitis. In three consecutive subjects, we tested the hypothesis that autoimmunity to retinal antigens might be a contributing factor.

SUBJECTS/METHODS

This was a multicentred, retrospective case series. Deidentified clinical data of subjects with both DS and uveitis were collected via questionnaire by uveitis-trained ophthalmologists. Anti-retinal autoantibodies (AAbs) were detected using an Autoimmune Retinopathy Panel tested in the OHSU Ocular Immunology Laboratory.

RESULTS

We characterized eight subjects (mean age 29 [range, 19-37] years). The mean age of detected uveitis onset was 23.5 [range, 11-33] years. All eight subjects had bilateral uveitis (p < 0.001 based on comparison to published university referral patterns), with anterior and intermediate uveitis found in six and five subjects respectively. Each of three subjects tested for anti-retinal AAbs was positive. Detected AAbs included anti-carbonic anhydrase II, anti-enolase, anti-arrestin, and anti-aldolase.

DISCUSSION

A partial deficiency in the AIRE on chromosome 21 has been described in DS. The similarities in the uveitis presentations within this patient group, the known autoimmune disease predisposition in DS, the recognized association of DS and AIRE deficiency, the reported detection of anti-retinal antibodies in patients with DS in general, and the presence of anti-retinal AAbs in three subjects in our series supports a causal association between DS and autoimmune eye disease.

Dysregulation of the Immune System in a Natural History Study of 1299 Individuals with Down Syndrome

Dysregulation of the immune system in individuals with Down syndrome is thought to play a major role in the pathophysiology of many clinical presentations. This natural history of disease study took a comprehensive evaluation of the prevalence of different immune related diagnoses in a cohort of 1299 patients with Down syndrome compared to a 2605 control cohort of patients without Down syndrome at Mount Sinai Health System in NY, NY over the past 18 years. We conducted a stepwise analysis of the odds of receiving a diagnosis at the Chapter, Sub-chapter and Diagnosis level of the ICD-CM-10 code system. Individuals in our Down syndrome cohort had higher odds of a diagnosis with inflammatory and autoimmune presentations such as Alopecia areata (OR 6.06, p = 0.01), Other sepsis (OR 4.79, p < 0.001, Purpura and Other hemorrhagic conditions (OR 2.31, p < 0.001), and Rosacea (OR 3.11, p < 0.001). They also presented with lower odds of a diagnosis of Herpesviral infection (OR 0.42, p = 0.01), and Viral warts (OR 0.51, p = 0.04). We posit that dysregulation of the immune system in individuals with Down syndrome has impact on infectious diseases, including lowering the incidence of viral disease, and increasing its severity. Our data also suggests inflammation and autoimmune mediated diseases, in particular of the skin, is exacerbated in individuals with Down syndrome. Finally, there may be a need for greater clinical attention to non-emergent conditions within the Down syndrome patient population as those can also greatly affect quality of life.

Lateral cephalometric characteristics in individuals with Down Syndrome compared to non-syndromic controls: A meta-analysis

OBJECTIVES

The aim of the present meta-analysis was to provide a complete synthesis of all studies involving lateral cephalometric measurements in populations with Down Syndrome (DS).

METHODS

A literature search was carried out using six electronic databases to identify studies comparing cephalometric characteristics between populations with DS and control (healthy) populations. Studies were selected according to the research objectives, and predefined inclusion and exclusion criteria. Only the cephalometric measurements included in three or more studies selected were analyzed. The random-effects meta-analysis model was used for data analysis, and all analyses were carried out using RevMan5 software.

RESULTS

From an initial 871 articles identified through the literature search, ten cross-sectional studies were finally selected based on the inclusion and exclusion criteria. Ten cephalometric measurements underwent meta-analysis, five linear and five angular measurements. Concerning the five linear measurements, namely S-N, ANS-PNS, Go-Gn, Ar-Go, and N-ANS, all were significantly smaller in the DS group with the exception of Go-Gn. Of the five angular measurements, only three were statistically different between the DS and control groups. SNB and ANB angles were smaller in individuals with DS, whereas the basilar angle was larger. Subgroup analysis was also carried out based on age, and it was found that the gonial angle was significantly smaller before puberty, in individuals with DS. No differences between groups were found for the SNA angle.

CONCLUSION

There are significant cephalometric differences between individuals with and without DS. Individuals with DS have a shorter anterior cranial base, maxillary length, upper anterior facial height and mandibular height. The ANB and SNB angles were also smaller in those with DS, but the SNA angle showed no differences. These findings may indicate that the Class III malocclusion commonly found in individuals with DS does not seem to be due to mandibular prognathism.

CLINICAL RELEVANCE

Lateral cephalometric measurements in individuals with DS show significant differences from individuals without DS. Practitioners need to be aware of this and monitor growth from an early age in these children.

Multidimensional definition of the interferonopathy of Down syndrome and its response to JAK inhibition

Individuals with Down syndrome (DS) display chronic hyperactivation of interferon signaling. However, the clinical impacts of interferon hyperactivity in DS are ill-defined. Here, we describe a multiomics investigation of interferon signaling in hundreds of individuals with DS. Using interferon scores derived from the whole blood transcriptome, we defined the proteomic, immune, metabolic, and clinical features associated with interferon hyperactivity in DS. Interferon hyperactivity associates with a distinct proinflammatory phenotype and dysregulation of major growth signaling and morphogenic pathways. Individuals with the highest interferon activity display the strongest remodeling of the peripheral immune system, including increased cytotoxic T cells, B cell depletion, and monocyte activation. Interferon hyperactivity accompanies key metabolic changes, most prominently dysregulated tryptophan catabolism. High interferon signaling stratifies a subpopulation with elevated rates of congenital heart disease and autoimmunity. Last, a longitudinal case study demonstrated that JAK inhibition normalizes interferon signatures with therapeutic benefit in DS. Together, these results justify the testing of immune-modulatory therapies in DS.

Modeling Alzheimer's disease related phenotypes in the Ts65Dn mouse: impact of age on Aβ, Tau, pTau, NfL, and behavior

Introduction

People with DS are highly predisposed to Alzheimer's disease (AD) and demonstrate very similar clinical and pathological features. Ts65Dn mice are widely used and serve as the best-characterized animal model of DS.

Methods

We undertook studies to characterize age-related changes for AD-relevant markers linked to Aβ, Tau, and phospho-Tau, axonal structure, inflammation, and behavior.

Results

We found age related changes in both Ts65Dn and 2N mice. Relative to 2N mice, Ts65Dn mice showed consistent increases in Aβ40, insoluble phospho-Tau, and neurofilament light protein. These changes were correlated with deficits in learning and memory.

Discussion

These data have implications for planning future experiments aimed at preventing disease-related phenotypes and biomarkers. Interventions should be planned to address specific manifestations using treatments and treatment durations adequate to engage targets to prevent the emergence of phenotypes.

From neurodevelopment to neurodegeneration: utilizing human stem cell models to gain insight into Down syndrome

Down syndrome (DS), caused by triplication of chromosome 21, is the most frequent aneuploidy observed in the human population and represents the most common genetic form of intellectual disability and early-onset Alzheimer's disease (AD). Individuals with DS exhibit a wide spectrum of clinical presentation, with a number of organs implicated including the neurological, immune, musculoskeletal, cardiac, and gastrointestinal systems. Decades of DS research have illuminated our understanding of the disorder, however many of the features that limit quality of life and independence of individuals with DS, including intellectual disability and early-onset dementia, remain poorly understood. This lack of knowledge of the cellular and molecular mechanisms leading to neurological features of DS has caused significant roadblocks in developing effective therapeutic strategies to improve quality of life for individuals with DS. Recent technological advances in human stem cell culture methods, genome editing approaches, and single-cell transcriptomics have provided paradigm-shifting insights into complex neurological diseases such as DS. Here, we review novel neurological disease modeling approaches, how they have been used to study DS, and what questions might be addressed in the future using these innovative tools.

Characterization of autoimmune eye disease in association with Down's Syndrome

Background Autoimmunity and deficiency of the transcription factor autoimmune regulator protein (AIRE) are known associations with Down Syndrome (DS). Lack of AIRE abrogates thymic tolerance. The autoimmune eye disease associated with DS has not been characterized. We identified a series of subjects with DS (n = 8) and uveitis. In 3 consecutive subjects, we tested the hypothesis that autoimmunity to retinal antigens might be a contributing factor. Subjects/Methods: This was a multicentered, retrospective case series. De-identified clinical data of subjects with both DS and uveitis were collected via questionnaire by uveitis-trained ophthalmologists. Anti-retinal autoantibodies (AAbs) were detected using an Autoimmune Retinopathy Panel tested in the OHSU Ocular Immunology Laboratory. Results We characterized 8 subjects (mean age 29 [range, 19-37] years). The mean age of uveitis onset was 23.5 [range, 11-33] years. All 8 subjects had bilateral uveitis (p < 0.001 based on comparison to published university referral patterns), with anterior and intermediate uveitis found in 6 and 5 subjects respectively. Each of three subjects tested for anti-retinal AAbs was positive. Detected AAbs included anti-carbonic anhydrase II, anti-enolase, anti-arrestin, and anti-aldolase. Discussion A partial deficiency in the AIRE on chromosome 21 has been described in DS. The similarities in the uveitis presentations within this patient group, the known autoimmune disease predisposition in DS, the recognized association of DS and AIRE deficiency, the reported detection of anti-retinal antibodies in patients with DS in general, and the presence of anti-retinal AAbs in 3 subjects in our series supports a causal association between DS and autoimmune eye disease.

Autoimmunity in Down's syndrome via cytokines, CD4 T cells and CD11c+ B cells

Down's syndrome (DS) presents with a constellation of cardiac, neurocognitive and growth impairments. Individuals with DS are also prone to severe infections and autoimmunity including thyroiditis, type 1 diabetes, coeliac disease and alopecia areata1,2. Here, to investigate the mechanisms underlying autoimmune susceptibility, we mapped the soluble and cellular immune landscape of individuals with DS. We found a persistent elevation of up to 22 cytokines at steady state (at levels often exceeding those in patients with acute infection) and detected basal cellular activation: chronic IL-6 signalling in CD4 T cells and a high proportion of plasmablasts and CD11c+TbethighCD21low B cells (Tbet is also known as TBX21). This subset is known to be autoimmune-prone and displayed even greater autoreactive features in DS including receptors with fewer non-reference nucleotides and higher IGHV4-34 utilization. In vitro, incubation of naive B cells in the plasma of individuals with DS or with IL-6-activated T cells resulted in increased plasmablast differentiation compared with control plasma or unstimulated T cells, respectively. Finally, we detected 365 auto-antibodies in the plasma of individuals with DS, which targeted the gastrointestinal tract, the pancreas, the thyroid, the central nervous system, and the immune system itself. Together, these data point to an autoimmunity-prone state in DS, in which a steady-state cytokinopathy, hyperactivated CD4 T cells and ongoing B cell activation all contribute to a breach in immune tolerance. Our findings also open therapeutic paths, as we demonstrate that T cell activation is resolved not only with broad immunosuppressants such as Jak inhibitors, but also with the more tailored approach of IL-6 inhibition.

IGF1 deficiency integrates stunted growth and neurodegeneration in Down syndrome

Down syndrome (DS), the genetic condition caused by trisomy 21 (T21), is characterized by stunted growth, cognitive impairment, and increased risk of diverse neurological conditions. Although signs of lifelong neurodegeneration are well documented in DS, the mechanisms underlying this phenotype await elucidation. Here we report a multi-omics analysis of neurodegeneration and neuroinflammation biomarkers, plasma proteomics, and immune profiling in a diverse cohort of more than 400 research participants. We identified depletion of insulin growth factor 1 (IGF1), a master regulator of growth and brain development, as the top biosignature associated with neurodegeneration in DS. Individuals with T21 display chronic IGF1 deficiency downstream of growth hormone production, associated with a specific inflammatory profile involving elevated tumor necrosis factor alpha (TNF-α). Shorter children with DS show stronger IGF1 deficiency, elevated biomarkers of neurodegeneration, and increased prevalence of autism and other conditions. These results point to disruption of IGF1 signaling as a potential contributor to stunted growth and neurodegeneration in DS.

Hemophagocytic lymphohistocytosis in trisomy 21: successful treatment with interferon inhibition

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of immune dysregulation primarily driven by the cytokine interferon gamma. It can be either a genetic or acquired disorder associated with infection, malignancy, and rheumatologic disorders. Trisomy 21 can express a wide range of phenotypes which include immune dysregulation and shares inherent pathophysiology with a group of disorders termed interferonopathies. Knowledge of this overlap in seemingly unrelated conditions could provide a basis for future research, and most importantly, alternative therapeutic interventions in acute life threatening clinical scenarios. Herein, we describe two patients with trisomy 21 presenting with HLH that was refractory to conventional treatment. Both patients were successfully managed with novel interventions targeting the interferon pathway.

CASE PRESENTATION

We describe a 17-month-old male and 15-month-old female with trisomy 21 presenting with a myriad of signs and symptoms including fever, rash, cytopenias, and hyperferritinemia, both ultimately diagnosed with HLH. Each had relapsing, refractory HLH over time requiring several admissions to the hospital receiving conventional high dose corticosteroids and interleukin-1 inhibition therapy. Successful steroid-free remission was achieved after targeting interferon inhibition with emapalumab induction followed by long-term maintenance on baricitinib.

CONCLUSION

To our knowledge, these are the first reported cases of relapsed, refractory HLH in patients with trisomy 21 successfully treated with emapalumab and transitioned to a steroid-sparing regimen with oral baricitinib for maintenance therapy. Trisomy 21 autoimmunity and HLH are both thought to be driven by interferon gamma. Targeting therapy toward interferon signaling in both HLH and autoimmunity in trisomy 21 may have potential therapeutic benefits. Further investigation is needed to determine if trisomy 21 may predispose to the development of HLH given this common pathway.

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.

The Underlying Relationship between Keratoconus and Down Syndrome

Keratoconus (KC) is one of the most significant corneal disorders worldwide, characterized by the progressive thinning and cone-shaped protrusion of the cornea, which can lead to severe visual impairment. The prevalence of KC varies greatly by ethnic groups and geographic regions and has been observed to be higher in recent years. Although studies reveal a possible link between KC and genetics, hormonal disturbances, environmental factors, and specific comorbidities such as Down Syndrome (DS), the exact cause of KC remains unknown. The incidence of KC ranges from 0% to 71% in DS patients, implying that as the worldwide population of DS patients grows, the number of KC patients may continue to rise significantly. As a result, this review aims to shed more light on the underlying relationship between KC and DS by examining the genetics relating to the cornea, central corneal thickness (CCT), and mechanical forces on the cornea, such as vigorous eye rubbing. Furthermore, this review discusses KC diagnostic and treatment strategies that may help detect KC in DS patients, as well as the available DS mouse models that could be used in modeling KC in DS patients. In summary, this review will provide improved clinical knowledge of KC in DS patients and promote additional KC-related research in these patients to enhance their eyesight and provide suitable treatment targets.

The innate immune system stimulating cytokine GM-CSF improves learning/memory and interneuron and astrocyte brain pathology in Dp16 Down syndrome mice and improves learning/memory in wild-type mice

Down syndrome (DS) is characterized by chronic neuroinflammation, peripheral inflammation, astrogliosis, imbalanced excitatory/inhibitory neuronal function, and cognitive deficits in both humans and mouse models. Suppression of inflammation has been proposed as a therapeutic approach to treating DS co-morbidities, including intellectual disability (DS/ID). Conversely, we discovered previously that treatment with the innate immune system stimulating cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF), which has both pro- and anti-inflammatory activities, improved cognition and reduced brain pathology in a mouse model of Alzheimer's disease (AD), another inflammatory disorder, and improved cognition and reduced biomarkers of brain pathology in a phase II trial of humans with mild-to-moderate AD. To investigate the effects of GM-CSF treatment on DS/ID in the absence of AD, we assessed behavior and brain pathology in 12-14 month-old DS mice (Dp[16]1Yey) and their wild-type (WT) littermates, neither of which develop amyloid, and found that subcutaneous GM-CSF treatment (5 μg/day, five days/week, for five weeks) improved performance in the radial arm water maze in both Dp16 and WT mice compared to placebo. Dp16 mice also showed abnormal astrocyte morphology, increased percent area of GFAP staining in the hippocampus, clustering of astrocytes in the hippocampus, and reduced numbers of calretinin-positive interneurons in the entorhinal cortex and subiculum, and all of these brain pathologies were improved by GM-CSF treatment. These findings suggest that stimulating and/or modulating inflammation and the innate immune system with GM-CSF treatment may enhance cognition in both people with DS/ID and in the typical aging population.

Down Syndrome-Associated Arthritis (DA): Diagnostic and Management Challenges

Down syndrome (DS) is one of the most common birth defects in the United States, the most common genomic disorder of intellectual disability, and results from trisomy 21. This chromosome disorder causes an extensive, heterogenous phenotype that results in a broad presentation of symptoms that includes atlantoaxial instability, congenital heart defects, muscle hypotonia, hypothyroidism, hematologic disorders, recurrent infections, and autoimmune diseases. The autoimmune diseases are caused by immune system dysregulation that results in increased pro-inflammatory cytokines, along with other innate and adaptive immune system dysregulation. This is the likely cause of the increased risk of inflammatory arthritis or Down syndrome-associated arthritis (DA) seen in individuals with DS. Most individuals with DA present with polyarticular (five or more joints with arthritis at presentation of disease), rheumatoid factor and anti-nuclear antibody negative disease that is aggressive with bone and joint damage at presentation. There is notable delay in diagnosis of DA as there are no formal guidelines on screening or monitoring for inflammatory arthritis in individuals with DS. Once diagnosed, and despite aggressive therapy with disease modifying antirheumatic drugs, disease burden is high for those with DA. Therapy can also be challenging for those with DA as many require second and third-line disease modifying therapies. Many also struggle with medication toxicity and ineffectiveness that further causes challenges with management and outcomes. The purpose of this current review is to provide an up-to-date summary of the literature related to DA in children and adolescents with focus on presentation, diagnosis, and management considerations, along with current barriers that inhibit optimal care.

Melatonin as an immunomodulator in children with Down syndrome

BACKGROUND

Down syndrome (DS) is a disorder characterised by marked immune dysfunction, increased mortality from sepsis, chronic inflammation, increased oxidative stress, sleep disturbance and possibly abnormal endogenous melatonin levels. Melatonin has a myriad of immune functions, and we hypothesised that this therapeutic agent could modulate the innate immune system in this cohort.

METHODS

We investigated neutrophil and monocyte function (CD11b, TLR4 expression by flow cytometry), genes involved in TLR signalling (MyD88, IRAK4, TRIF), the inflammasome (NLRP3, IL-1β), and circadian rhythm (BMAL, CLOCK, CRY) by qPCR, and inflammatory cytokines (IL-2, IL-6, IL-8, IL-18, IL-1β, TNF-α, IFN-γ, IL-10, IL-1ra, VEGF, Epo, GM-CSF) by enzyme-linked immunosorbent assay (ELISA) following immunomodulation with LPS endotoxin and melatonin. 47 children with DS and 23 age- and sex-matched controls were recruited.

RESULTS

We demonstrated that melatonin has several significant effects by reducing CD11b and TLR4 expression, attenuating TLR signalling, genes involved in the inflammasome and has the potential to reduce LPS-induced inflammatory responses.

CONCLUSIONS

Immunomodulatory effects of melatonin were found in both paediatric cohorts with more marked effects in the children with DS. Melatonin mediates immune response through a wide array of mechanisms and this immunomodulator may buffer the inflammatory response by regulating pro and anti-inflammatory signalling.

IMPACT

We highlight that melatonin mediates its immune response through a wide array of mechanisms, its effects appear to be dose dependant and children with Down syndrome may be more receptive to treatment with it. Immunomodulatory effects of melatonin were demonstrated with marked effects in the children with Down syndrome with a reduction of MyD88, IL-1ß and NLRP3 expression in whole-blood samples. Melatonin is a proposed anti-inflammatory agent with a well-established safety profile, that has the potential for mitigation of pro- and anti-inflammatory cytokines in paediatric Down syndrome cohorts, though further clinical trials are warranted.

Infants with Down syndrome and congenital heart disease have altered peri-operative immune responses

BACKGROUND

Infants with Down syndrome (DS) have an altered immune response. We aimed to characterise the inflammatory response in infants with DS and congenital heart disease (CHD) peri-operatively in comparison to infants with CHD and a normal chromosomal complement, and to healthy infants pre-operatively.

METHODS

Infants with DS/CHD, infants without DS but with CHD (CHD only) and healthy infants were prospectively recruited and serial serum cytokines evaluated peri-operatively using multiplex ELISA: tumour necrosis factor (TNF)-α and TNF-β; interferon (IFN)-γ, interleukin (IL)-1α, IL-2, IL-6, IL-8, IL-18, IL-1β, IL-10, and IL-1ra; vascular endothelial growth factor (VEGF); granulocyte macrophage colony-stimulating factor (GM-CSF); and erythropoietin (EPO).

RESULTS

Ninety-four infants were recruited including age-matched controls (n = 10), DS/CHD (n = 55), and CHD only (n = 29). Children with DS/CHD had significantly lower concentrations of several cytokines (IL-10, IL-6, IL-8, IL-1β, VEGF) in the pre- and post-operatively vs CHD only and controls. EPO and GM-CSF were significantly higher in DS/CHD (p value <0.05).

CONCLUSIONS

Children with DS/CHD had significantly lower concentrations of several cytokines compared to controls or children with CHD only. EPO and GM-CSF were significantly higher in children with DS/CHD. The assessment of the immune response may be suitable for the predictable clinical outcomes in these children.

IMPACT

This study demonstrated that children with Down syndrome (DS) and congenital heart disease (CHD) have significant alterations in pro-inflammatory and anti-inflammatory immune responses peri-operatively. These changes may contribute to adverse clinical outcomes, including sepsis, chylothorax, and autoimmunity. They may impact the pathogenesis and outcome post-operatively and long term in this population. Children with DS and CHD have significantly lower cytokine concentrations, increased EPO and GM-CSF, and decreased VEGF pre- and post-operatively. Assessing their inflammatory state peri-operatively may facilitate the development of a predictive model that can inform tailored management of these infants using novel therapies including immunomodulation.

Atypical Inflammatory Syndrome Triggered by SARS-CoV-2 in Infants with Down Syndrome

While adults with Down syndrome (DS) are at increased risk of severe COVID-19 pneumonia, little is known about COVID-19 in children with DS. In children without DS, SARS-CoV-2 can rarely cause severe COVID-19 pneumonia, or an even rarer and more typically pediatric condition, multisystem inflammatory syndrome in children (MIS-C). Although the underlying mechanisms are still unknown, MIS-C is thought to be primarily immune-mediated. Here, we describe an atypical, severe form of MIS-C in two infant girls with DS who were hospitalized for over 4 months. Immunological evaluation revealed pronounced neutrophilia, B cell depletion, increased circulating IL-6 and IL-8, and elevated markers of immune activation ICAM1 and FcɣRI. Importantly, uninfected children with DS presented with similar but less stark immune features at steady state, possibly explaining risk of further uncontrolled inflammation following SARS-CoV-2 infection. Overall, a severe, atypical form of MIS-C may occur in children with DS.

Innate Immune System Activation and Neuroinflammation in Down Syndrome and Neurodegeneration: Therapeutic Targets or Partners?

Innate immune system activation and inflammation are associated with and may contribute to clinical outcomes in people with Down syndrome (DS), neurodegenerative diseases such as Alzheimer's disease (AD), and normal aging. In addition to serving as potential diagnostic biomarkers, innate immune system activation and inflammation may play a contributing or causal role in these conditions, leading to the hypothesis that effective therapies should seek to dampen their effects. However, recent intervention studies with the innate immune system activator granulocyte-macrophage colony-stimulating factor (GM-CSF) in animal models of DS, AD, and normal aging, and in an AD clinical trial suggest that activating the innate immune system and inflammation may instead be therapeutic. We consider evidence that DS, AD, and normal aging are accompanied by innate immune system activation and inflammation and discuss whether and when during the disease process it may be therapeutically beneficial to suppress or promote such activation.

Meta-analysis of transcriptomic data reveals clusters of consistently deregulated gene and disease ontologies in Down syndrome

Trisomy of human chromosome 21 (HSA21) causes Down syndrome (DS). The trisomy does not simply result in the upregulation of HSA21--encoded genes but also leads to a genome-wide transcriptomic deregulation, which affect differently each tissue and cell type as a result of epigenetic mechanisms and protein-protein interactions. We performed a meta-analysis integrating the differential expression (DE) analyses of all publicly available transcriptomic datasets, both in human and mouse, comparing trisomic and euploid transcriptomes from different sources. We integrated all these data in a "DS network". We found that genome wide deregulation as a consequence of trisomy 21 is not arbitrary, but involves deregulation of specific molecular cascades in which both HSA21 genes and HSA21 interactors are more consistently deregulated compared to other genes. In fact, gene deregulation happens in "clusters", so that groups from 2 to 13 genes are found consistently deregulated. Most of these events of "co-deregulation" involve genes belonging to the same GO category, and genes associated with the same disease class. The most consistent changes are enriched in interferon related categories and neutrophil activation, reinforcing the concept that DS is an inflammatory disease. Our results also suggest that the impact of the trisomy might diverge in each tissue due to the different gene set deregulation, even though the triplicated genes are the same. Our original method to integrate transcriptomic data confirmed not only the importance of known genes, such as SOD1, but also detected new ones that could be extremely useful for generating or confirming hypotheses and supporting new putative therapeutic candidates. We created "metaDEA" an R package that uses our method to integrate every kind of transcriptomic data and therefore could be used with other complex disorders, such as cancer. We also created a user-friendly web application to query Ensembl gene IDs and retrieve all the information of their differential expression across the datasets.

Blood Biomarkers for Alzheimer's Disease in Down Syndrome

Epidemiological evidence suggests that by the age of 40 years, all individuals with Down syndrome (DS) have Alzheimer's disease (AD) neuropathology. Clinical diagnosis of dementia by cognitive assessment is complex in these patients due to the pre-existing and varying intellectual disability, which may mask subtle declines in cognitive functioning. Cerebrospinal fluid (CSF) and positron emission tomography (PET) biomarkers, although accurate, are expensive, invasive, and particularly challenging in such a vulnerable population. The advances in ultra-sensitive detection methods have highlighted blood biomarkers as a valuable and realistic tool for AD diagnosis. Studies with DS patients have proven the potential blood-based biomarkers for sporadic AD (amyloid-β, tau, phosphorylated tau, and neurofilament light chain) to be useful in this population. In addition, biomarkers related to other pathologies that could aggravate dementia progression-such as inflammatory dysregulation, energetic imbalance, or oxidative stress-have been explored. This review serves to provide a brief overview of the main findings from the limited neuroimaging and CSF studies, outline the current state of blood biomarkers to diagnose AD in patients with DS, discuss possible past limitations of the research, and suggest considerations for developing and validating blood-based biomarkers in the future.

High-resolution functional connectivity of the default mode network in young adults with down syndrome

Studies of resting-state functional connectivity MRI in Alzheimer's disease suggest that disease stage plays a role in functional changes of the default mode network. Individuals with the genetic disorder Down syndrome show an increased incidence of early-onset Alzheimer's-type dementia, along with early and nearly universal neuropathologic changes of Alzheimer's disease. The present study examined high-resolution functional connectivity of the default mode network in 11 young adults with Down syndrome that showed no measurable symptoms of dementia and 11 age- and sex-matched neurotypical controls. We focused on within-network connectivity of the default mode network, measured from both anterior and posterior aspects of the cingulate cortex. Sixty-eight percent of connections to the posterior cingulate and 26% to the anterior cingulate showed reduced strength in the group with Down syndrome (p < 0.01). The Down syndrome group showed increased connectivity strength from the anterior cingulate to the bilateral inferior frontal gyri and right putamen (p < 0.005). In an exploratory analysis, connectivity in the group with Down syndrome showed regional relationships to plasma measures of inflammatory markers and t-tau. In non-demented adults with Down syndrome, functional connectivity within the default mode network may be analogous to changes reported in preclinical Alzheimer's disease, and warrants further investigation as a measure of dementia risk.

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 type I interferon: not so simple

Down syndrome (DS) is characterized by a collection of clinical features including intellectual disability, congenital malformations, and susceptibility to infections and autoimmune diseases. While the presence of an extra chromosome 21 is known to cause DS, the precise genetic annotation linked to specific clinical features is largely missing. However, there is growing evidence that two genes located on chromosome 21, IFNAR1 and IFNAR2, play an important role in disease pathogenesis. These genes encode the two subunits of the receptor for type I interferons (IFN-I), a group of potent antiviral and pro-inflammatory cytokines. Human monogenic diseases caused by uncontrolled IFN-I production and response have been well characterized, and they clinically overlap with DS but also have notable differences. Herein, we review the literature characterizing the role of IFN-I in DS and compare and contrast DS to other IFN-mediated conditions. The existing IFN-I literature serves as a rich resource for testable hypotheses to elucidate disease mechanisms in DS and is likely to open novel therapeutic avenues.

Genetic Susceptibility to Periodontal Disease in Down Syndrome: A Case-Control Study

Severe periodontitis is prevalent in Down syndrome (DS). This study aimed to identify genetic variations associated with periodontitis in individuals with DS. The study group was distributed into DS patients with periodontitis (n = 50) and DS patients with healthy periodontium (n = 36). All samples were genotyped with the “Axiom Spanish Biobank” array, which contains 757,836 markers. An association analysis at the individual marker level using logistic regression, as well as at the gene level applying the sequence kernel association test (SKAT) was performed. The most significant genes were included in a pathway analysis using the free DAVID software. C12orf74 (rs4315121, p = 9.85 × 10⁻⁵, OR = 8.84), LOC101930064 (rs4814890, p = 9.61 × 10⁻⁵, OR = 0.13), KBTBD12 (rs1549874, p = 8.27 × 10⁻⁵, OR = 0.08), PIWIL1 (rs11060842, p = 7.82 × 10⁻⁵, OR = 9.05) and C16orf82 (rs62030877, p = 8.92 × 10⁻⁵, OR = 0.14) showed a higher probability in the individual analysis. The analysis at the gene level highlighted PIWIL, MIR9-2, LHCGR, TPR and BCR. At the signaling pathway level, PI3K-Akt, long-term depression and FoxO achieved nominal significance (p = 1.3 × 10⁻², p = 5.1 × 10⁻³, p = 1.2 × 10⁻², respectively). In summary, various metabolic pathways are involved in the pathogenesis of periodontitis in DS, including PI3K-Akt, which regulates cell proliferation and inflammatory response.

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.

Trisomy 21 impairs PGE2 production in dermal fibroblasts

The triplication of human chromosome 21 results in Down syndrome (DS), the most common genetic form of intellectual disability. This aneuploid condition also results in an enhanced risk of a spectrum of comorbid conditions, such as leukemia, early onset Alzheimer's disease, and diabetes. Individuals with DS also display an increased incidence of wound healing complications and resistance to solid tumor development. Due to this unique phenotype and the involvement of eicosanoids in key comorbidities like poor healing and tumor development, we hypothesized that cells from DS individuals would display altered eicosanoid production. Using age- and sex-matched dermal fibroblasts we interrogated this hypothesis. Briefly, assessment of over 90 metabolites derived from cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome p450 systems revealed a possible deficiency in the COX system. Basal gene expression and Western blotting experiments showed significantly decreased gene expression of COX1 and 2, and COX2 protein abundance in DS fibroblasts compared to euploid controls. Further, using two different stressors, scratch wound or LPS, we found that DS fibroblasts could not upregulate COX2 abundance and prostaglandin E2 production. Together, these findings show that dermal fibroblasts from DS individuals have a deficient COX2 response, which may contribute to wound healing complications and tumor resistance in DS.

Clinical Presentation and Successful Management of an Infant With Down Syndrome and COVID-19 in Riyadh, Saudi Arabia

Coronavirus is a serious, global disease. Down syndrome (DS) is characterized by immune dysregulation, has various anatomical variations, and is considered as comorbidity. These variations mean that children with DS are at risk of developing a severe case of COVID-19 if the virus is contracted. Here, we report the first case of COVID-19 in a four-month-old infant girl with DS and congenital heart disease (CHD) who was treated in Al-Imam Abdulrahman Al Faisal Hospital in the first health cluster in Riyadh, Saudi Arabia. The medical management and clinical outcome of the infant are reviewed. The infant was admitted after having received previous treatment from other hospitals, with a deteriorating condition. The patient had developed a rash, and oxygen support was required in addition to her baseline medication (furosemide and captopril). Ten days post admission, the patient's condition improved, and she became clinically stable. She was then discharged after two consecutive negative nasopharyngeal swabs. Based on the reported case, infants with DS and CHD should be considered a high-risk patient in terms of COVID-19 infection and require close observation.

Apigenin as a Candidate Prenatal Treatment for Trisomy 21: Effects in Human Amniocytes and the Ts1Cje Mouse Model

Human fetuses with trisomy 21 (T21) have atypical brain development that is apparent sonographically in the second trimester. We hypothesize that by analyzing and integrating dysregulated gene expression and pathways common to humans with Down syndrome (DS) and mouse models we can discover novel targets for prenatal therapy. Here, we tested the safety and efficacy of apigenin, identified with this approach, in both human amniocytes from fetuses with T21 and in the Ts1Cje mouse model. In vitro, T21 cells cultured with apigenin had significantly reduced oxidative stress and improved antioxidant defense response. In vivo, apigenin treatment mixed with chow was administered prenatally to the dams and fed to the pups over their lifetimes. There was no significant increase in birth defects or pup deaths resulting from prenatal apigenin treatment. Apigenin significantly improved several developmental milestones and spatial olfactory memory in Ts1Cje neonates. In addition, we noted sex-specific effects on exploratory behavior and long-term hippocampal memory in adult mice, and males showed significantly more improvement than females. We demonstrated that the therapeutic effects of apigenin are pleiotropic, resulting in decreased oxidative stress, activation of pro-proliferative and pro-neurogenic genes (KI67, Nestin, Sox2, and PAX6), reduction of the pro-inflammatory cytokines INFG, IL1A, and IL12P70 through the inhibition of NFκB signaling, increase of the anti-inflammatory cytokines IL10 and IL12P40, and increased expression of the angiogenic and neurotrophic factors VEGFA and IL7. These studies provide proof of principle that apigenin has multiple therapeutic targets in preclinical models of DS.

Individuals with Down syndrome hospitalized with COVID-19 have more severe disease

PURPOSE

Rare genetic conditions like Down syndrome (DS) are historically understudied. Infection is a leading cause of mortality in DS, along with cardiac anomalies. Currently, it is unknown how the COVID-19 pandemic affects individuals with DS. Herein, we report an analysis of individuals with DS who were hospitalized with COVID-19 in New York, New York, USA.

METHODS

In this retrospective, dual-center study of 7246 patients hospitalized with COVID-19, we analyzed all patients with DS admitted in the Mount Sinai Health System and Columbia University Irving Medical Center. We assessed hospitalization rates, clinical characteristics, and outcomes.

RESULTS

We identified 12 patients with DS. Hospitalized individuals with DS are on average ten years younger than patients without DS. Patients with DS have more severe disease than controls, particularly an increased incidence of sepsis and mechanical ventilation.

CONCLUSION

We demonstrate that individuals with DS who are hospitalized with COVID-19 are younger than their non-DS counterparts, and that they have more severe disease than age-matched controls. We conclude that particular care should be considered for both the prevention and treatment of COVID-19 in these patients.

SARS-CoV-2 Infection in Patients with Down Syndrome, Congenital Heart Disease, and Pulmonary Hypertension: Is Down Syndrome a Risk Factor?

With increasing information available about the epidemiology, pathophysiology, and management of patients affected with severe acute respiratory syndrome corona virus-2 infection, patients with Down syndrome, congenital heart disease, airway obstruction, and pulmonary hypertension present a unique challenge. This case series describes 3 patients with Down syndrome and respiratory failure secondary to coronavirus infection.

PNPLA3 gene polymorphism is associated with liver steatosis in children with Down syndrome

BACKGROUND AND AIMS

We previously demonstrated that children with Down syndrome (DS) exhibited a greater risk of steatosis than the general pediatric population. This trend was independent of obese phenotype, thus suggesting a role of genetic predisposition. Therefore, we investigated the prevalence of non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MetS) in function of genetic susceptibility and adipocytokine levels in children with DS.

METHODS AND RESULTS

A total of 84 Caucasian children with DS (age range 5-17 years), were included in this study. For all children, we collected data on anthropometric and biochemical parameters, and liver ultrasound (US). We also measured adipocytokines circulating levels and specific polymorphisms closed to NAFLD. We found a prevalence of 64.3% of liver steatosis at US, with a severe steatosis of about 4% in children with DS. The presence of steatosis in children with DS was associated with the presence of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 variant, which also correlated with interleukin (IL)-6 levels. Moreover, we found that the 52.4% had a waist circumference > 90th percentile, 21.4% were hypertensive, 7.14% had hyperglycemia, 9.5% had hypertriglyceridemia, and 17.9% showed high-density lipoprotein cholesterol ≤ 40 mg/dl. Finally, the IL-6 and adiponectin levels correlated with steatosis, and several adipocytokines correlated with single MetS traits in children with DS.

CONCLUSION

The present study explores for the first time potential pathomechanisms connecting pediatric NAFLD and MetS in DS. We found that the PNPLA3 variant is associated with steatosis, but not with MetS, in children with DS.

Down syndrome, accelerated aging and immunosenescence

Down syndrome is the most common chromosomal disorder, associated with moderate to severe intellectual disability. While life expectancy of Down syndrome population has greatly increased over the last decades, mortality rates are still high and subjects are facing prematurely a phenomenon of atypical and accelerated aging. The presence of an immune impairment in Down syndrome subjects is suggested for a long time by the existence of an increased incidence of infections, the incomplete efficacy of vaccinations, and a high prevalence of autoimmunity. Immunologic abnormalities have been described since many years in this population, both from a numerical and a functional points of view, and these abnormalities can mirror the ones observed during normal aging. In this review, we summarize our knowledge on immunologic disturbances commonly observed in subjects with Down syndrome, and in innate and adaptive immunity, as well as regarding chronic inflammation. We then discuss the role of accelerated aging in these observed abnormalities and finally review the potential age-associated molecular and cellular mechanisms involved.

Down Syndrome Is a Metabolic Disease: Altered Insulin Signaling Mediates Peripheral and Brain Dysfunctions

Down syndrome (DS) is the most frequent chromosomal abnormality that causes intellectual disability, resulting from the presence of an extra complete or segment of chromosome 21 (HSA21). In addition, trisomy of HSA21 contributes to altered energy metabolism that appears to be a strong determinant in the development of pathological phenotypes associated with DS. Alterations include, among others, mitochondrial defects, increased oxidative stress levels, impaired glucose, and lipid metabolism, finally resulting in reduced energy production and cellular dysfunctions. These molecular defects seem to account for a high incidence of metabolic disorders, i.e., diabetes and/or obesity, as well as a higher risk of developing Alzheimer’s disease (AD) in DS. A dysregulation of the insulin signaling with reduced downstream pathways represents a common pathophysiological aspect in the development of both peripheral and central alterations leading to diabetes/obesity and AD. This is further strengthened by evidence showing that the molecular mechanisms responsible for such alterations appear to be similar between peripheral organs and brain. Considering that DS subjects are at high risk to develop either peripheral or brain metabolic defects, this review will discuss current knowledge about the link between trisomy of HSA21 and defects of insulin and insulin-related pathways in DS. Drawing the molecular signature underlying these processes in DS is a key challenge to identify novel drug targets and set up new prevention strategies aimed to reduce the impact of metabolic disorders and cognitive decline.

Proteomic profiles for Alzheimer's disease and mild cognitive impairment among adults with Down syndrome spanning serum and plasma: An Alzheimer's Biomarker Consortium-Down Syndrome (ABC-DS) study

INTRODUCTION

Previously generated serum and plasma proteomic profiles were examined among adults with Down syndrome (DS) to determine whether these profiles could discriminate those with mild cognitive impairment (MCI-DS) and Alzheimer's disease (DS-AD) from those cognitively stable (CS).

METHODS

Data were analyzed on n = 305 (n = 225 CS; n = 44 MCI-DS; n = 36 DS-AD) enrolled in the Alzheimer's Biomarker Consortium-Down Syndrome (ABC-DS).

RESULTS

Distinguishing MCI-DS from CS, the serum profile produced an area under the curve (AUC) = 0.95 (sensitivity [SN] = 0.91; specificity [SP] = 0.99) and an AUC = 0.98 (SN = 0.96; SP = 0.97) for plasma when using an optimized cut-off score. Distinguishing DS-AD from CS, the serum profile produced an AUC = 0.93 (SN = 0.81; SP = 0.99) and an AUC = 0.95 (SN = 0.86; SP = 1.0) for plasma when using an optimized cut-off score. AUC remained unchanged to slightly improved when age and sex were included. Eotaxin3, interleukin (IL)-10, C-reactive protein, IL-18, serum amyloid A , and FABP3 correlated fractions at r2 > = 0.90.

DISCUSSION

Proteomic profiles showed excellent detection accuracy for MCI-DS and DS-AD.

Multiorgan involvement and management in children with Down syndrome

AIM

To review multiorgan involvement and management in children with Down syndrome (DS).

METHODS

A literature review of articles from 1980 to 2019 using the MEDLINE interface of PubMed was performed using the following search terms- [Down syndrome] or [Trisomy 21] AND [Cardiology] or [Respiratory] or [neurodevelopment] or [epilepsy] or [musculoskeletal] or [immune system] or [haematological] or [endocrine] or [gastrointestinal] or [ophthalmological] or [Ear Nose Throat] or [dermatology] or [renal].

RESULTS

Congenital heart disease particularly septal defects occur in over 60% of infants with DS and 5%-34% of infants develop persistent pulmonary hypertension of the newborn irrespective of a diagnosis of congenital heart disease. Early recognition and management of aspiration, obstructive sleep apnoea and recurrent lower respiratory tract infections (LRTI) could reduce risk of developing pulmonary hypertension in later childhood. Children with DS have an increased risk of autistic spectrum disorder, attention deficit disorder and epilepsy particularly infantile spasms, which are associated with poor neurodevelopmental outcomes. Congenital anomalies of the gastrointestinal and renal system as well as autoimmune diseases, coeliac disease, arthropathy, thyroid dysfunction fold diabetes mellitus and dermatological conditions are more common. Hearing and visual anomalies are also well recognised association with DS (Table 1).

CONCLUSION

Children with DS are at an increased risk of multiorgan comorbidities. Organ-specific health surveillance may provide holistic care for the children and families with DS throughout childhood.

Proteomic profiles of incident mild cognitive impairment and Alzheimer's disease among adults with Down syndrome

INTRODUCTION

We sought to determine if proteomic profiles could predict risk for incident mild cognitive impairment (MCI) and Alzheimer's disease (AD) among adults with Down syndrome (DS).

METHODS

In a cohort of 398 adults with DS, a total of n = 186 participants were determined to be non-demented and without MCI or AD at baseline and throughout follow-up; n = 103 had incident MCI and n = 81 had incident AD. Proteomics were conducted on banked plasma samples from a previously generated algorithm.

RESULTS

The proteomic profile was highly accurate in predicting incident MCI (area under the curve [AUC] = 0.92) and incident AD (AUC = 0.88). For MCI risk, the support vector machine (SVM)-based high/low cut-point yielded an adjusted hazard ratio (HR) = 6.46 (P < .001). For AD risk, the SVM-based high/low cut-point score yielded an adjusted HR = 8.4 (P < .001).

DISCUSSION

The current results provide support for our blood-based proteomic profile for predicting risk for MCI and AD among adults with DS.

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.

Proteomic profiles of prevalent mild cognitive impairment and Alzheimer's disease among adults with Down syndrome

INTRODUCTION

We sought to determine if a proteomic profile approach developed to detect Alzheimer's disease (AD) in the general population would apply to adults with Down syndrome (DS).

METHODS

Plasma samples were obtained from 398 members of a community-based cohort of adults with DS. A total of n = 186 participants were determined to be non-demented and without mild cognitive impairment (MCI) at baseline and throughout follow-up; n = 50 had prevalent MCI; n = 42 had prevalent AD.

RESULTS

The proteomic profile yielded an area under the curve (AUC) of 0.92, sensitivity (SN) = 0.80, and specificity (SP) = 0.98 detecting prevalent MCI. For detecting prevalent AD, the proteomic profile yielded an AUC of 0.89, SN = 0.81, and SP = 0.97. The overall profile closely resembled our previously published profile of AD in the general population.

DISCUSSION

These data provide evidence of the applicability of our blood-based algorithm for detecting MCI/AD among adults with DS.

An Altered Relationship between Soluble TREM2 and Inflammatory Markers in Young Adults with Down Syndrome: A Preliminary Report

Individuals with Down syndrome (DS) develop Alzheimer's disease (AD)-related neuropathology, characterized by amyloid plaques with amyloid β (Aβ) and neurofibrillary tangles with tau accumulation. Peripheral inflammation and the innate immune response are elevated in DS. Triggering receptor expressed in myeloid cells 2 (TREM2) genetic variants are risk factors for AD and other neurodegenerative diseases. Soluble TREM2 (sTREM2), a soluble cleavage product of TREM2, is elevated in AD cerebrospinal fluid and positively correlates with cognitive decline. There is relatively little information about TREM2 in DS. Our objective was to examine the relationship between sTREM2 and inflammatory markers in young adults with DS, prior to the development of dementia symptoms. Because TREM2 plays a role in the innate immune response and has been associated with dementia, the hypothesis of this exploratory study was that young adults with DS predementia (n = 15, mean age = 29.5 y) would exhibit a different relationship between sTREM2 and inflammatory markers in plasma, compared with neurotypical, age-matched controls (n = 16, mean age = 29.6 y). Indeed, young adults with DS had significantly elevated plasma sTREM2 and inflammatory markers. Additionally, in young adults with DS, sTREM2 correlated positively with 24 of the measured cytokines, whereas there were no significant correlations in the control group. Hierarchical clustering of sTREM2 and cytokine concentrations also differed between the groups, supporting the hypothesis that its function is altered in people with DS predementia. This preliminary report of human plasma provides a basis for future studies investigating the relationship between TREM2 and the broader immune response predementia.

Inflammation and fatness in adolescents with and without Down syndrome: UP & DOWN study

BACKGROUND

The main objective of this study was to describe the inflammatory status of adolescents with Down syndrome (DS) and their relationship with adiposity.

METHODS

Ninety-five adolescents with DS (44.2% girls) and a control group of 113 adolescents (47.8% girls), aged between 11 and 18 years old, from the UP & DOWN study were included in this substudy. Serum C-reactive protein, C3 and C4 complement factors, total proteins, interleukin-6, tumour necrosis factor-α, insulin, cortisol, leptin, adiponectin, galactin-3 and visfatin were analysed; homeostatic model assessment index was calculated. In order to evaluate adiposity, we measured the following body fat variables: weight, height, waist circumference and skinfold thicknesses. Birth weight was obtained by questionnaire. In addition, body mass index, waist-to-height ratio (WHtR) and body fat percentage (BF%) were calculated.

RESULTS

Down syndrome group showed higher levels of body mass index, WHtR, waist circumference, BF% and lower birth weight than controls (P < 0.001). In the general linear model in the total sample, WHtR was positively associated with C3 and C4 (P < 0.001) as well as with leptin levels (P = 0.015). BF% was positively associated with total proteins (P = 0.093) and leptin levels (P < 0.001). DS was positively associated with total proteins (P < 0.001), C3 (P = 0.047) and C4 (P = 0.019). Despite the higher levels of adiposity found in DS group, no direct association was found between BF% and leptin levels, comparing with the control group.

CONCLUSIONS

These findings suggest that abdominal obesity should be controlled in adolescents because of its relationship with acute phase-inflammatory biomarkers but especially in DS adolescents who may show a peculiar metabolic status according to their relationship between adiposity and inflammatory biomarkers.

RvE1 treatment prevents memory loss and neuroinflammation in the Ts65Dn mouse model of Down syndrome

Inflammation can be resolved by pro-homeostatic lipids called specialized pro-resolving mediators (SPMs) upon activation of their receptors. Dysfunctional inflammatory resolution is now considered as a driver of chronic neuroinflammation and Alzheimer's disease (AD) pathogenesis. We have previously shown that SPM levels were reduced and also that SPM-binding receptors were increased in patients with AD compared to age-matched controls. Individuals with Down syndrome (DS) exhibit accelerated acquisition of AD neuropathology, dementia, and neuroinflammation at an earlier age than the general population. Beneficial effects of inducing resolution in DS have not been investigated previously. The effects of the SPM resolvin E1 (RvE1) in a DS mouse model (Ts65Dn) were investigated with regard to inflammation, neurodegeneration, and memory deficits. A moderate dose of RvE1 for 4 weeks in middle-aged Ts65Dn mice elicited a significant reduction in memory loss, along with reduced levels of serum pro-inflammatory cytokines, and reduced microglial activation in the hippocampus of Ts65Dn mice but had no effects in age-matched normosomic mice. There were no observable adverse side effects in Ts65Dn or in normosomic mice. These findings suggest that SPMs may represent a novel drug target for individuals with DS and others at risk of developing AD.

Immune Dysregulation in Children With Down Syndrome

Down syndrome (DS) is the most common genetic syndrome associated with immune defects. The extent of immune dysregulation in DS is substantial, spanning the innate and adaptive systems and including anomalies in: T and B cells, monocytes, neutrophil chemotaxis, circulating cytokines, and suboptimal antibody responses which all contribute to an increased risk of infections, poorer clinical outcomes and chronic inflammation in this vulnerable cohort. Other aspects of innate immunity may also be abnormal and contribute to the increased morbidity and warrant further interrogation such as: gamma delta T cell function, the inflammasome, Toll-like receptors and their pathways. Pharmacotherapies such as pavilizumab, pneumococcal and influenza immunizations, as well as potential immunoprophylactic agents such as pidotimod, azithromycin and Broncho-Vaxom may help alleviate the infectious consequences. Children with DS need to be managed with a heightened sense of awareness and urgency in the setting of sepsis and signs of chronic inflammation need regular screening and appropriate follow up.

Increased systemic inflammation in children with Down syndrome

Children with Down syndrome (DS) develop more infections, have an increased mortality from sepsis and an increased incidence of chronic inflammatory conditions. Cytokine dysregulation may underpin these clinical sequelae and raised pro-inflammatory biomarkers are a feature in adults with DS. The importance of the anti-inflammatory mediators IL-1ra and IL-10, as well as cytokines Epo and VEGF, which could impact on the pathogenesis and outcomes in congenital heart disease (CHD) which is more prevalent in DS, are less well known. We examined a comprehensive array of pro-(IL-2, IL-6, IL-8, IL-18, IL-1β, TNF-α, IFN-γ), and anti-inflammatory (IL-10 and IL-1ra) mediators, cytokines involved in inflammation in response to hypoxia (EPO), propagating angiogenesis (VEGF), and myelopoiesis (GM-CSF), by enzyme linked immunosorbent assay (ELISA), as well as discussing the potential impact of significant CHD and Lipopolysaccharide endotoxin on these mediators. 114 children with DS and 60 age and sex matched controls were recruited. Children with Down syndrome exhibit significantly greater levels of pro and anti-inflammatory cytokines; IL-2, IL-6, IL-10, IL-1ra, as well as increased Epo, VEGF and GM-CSF at baseline. CHD does not seem to have an impact on circulating cytokines beyond the acute surgical phase. Both cohorts had similar responses to LPS stimulation. These differences may contribute to varied clinical outcomes, acutely like in sepsis, and over time in autoimmunity.

Trisomy 21 dysregulates T cell lineages toward an autoimmunity-prone state associated with interferon hyperactivity

Triplication of human chromosome 21, or trisomy 21 (T21), causes the condition known as Down syndrome (DS). People with DS show a markedly different disease spectrum relative to typical people, being highly predisposed to conditions such as Alzheimer’s disease, while being protected from other conditions, such as most solid malignancies. Interestingly, people with DS are affected by high rates of autoimmune disorders, whereby the immune system mistakenly attacks healthy tissues. This manuscript reports an exhaustive characterization of the T cells of people with DS, demonstrating many alterations in this key immune cell type that could explain their high risk of autoimmunity. These results reveal opportunities for therapeutic intervention to modulate T cell function and improve health outcomes in DS.

Trisomy 21 (T21) causes Down syndrome (DS), a condition characterized by high prevalence of autoimmune disorders. However, the molecular and cellular mechanisms driving this phenotype remain unclear. Building upon our previous finding that T cells from people with DS show increased expression of interferon (IFN)-stimulated genes, we have completed a comprehensive characterization of the peripheral T cell compartment in adults with DS with and without autoimmune conditions. CD8+ T cells from adults with DS are depleted of naïve subsets and enriched for differentiated subsets, express higher levels of markers of activation and senescence (e.g., IFN-γ, Granzyme B, PD-1, KLRG1), and overproduce cytokines tied to autoimmunity (e.g., TNF-α). Conventional CD4+ T cells display increased differentiation, polarization toward the Th1 and Th1/17 states, and overproduction of the autoimmunity-related cytokines IL-17A and IL-22. Plasma cytokine analysis confirms elevation of multiple autoimmunity-related cytokines (e.g., TNF-α, IL17A–D, IL-22) in people with DS, independent of diagnosis of autoimmunity. Although Tregs are more abundant in DS, functional assays show that CD8+ and CD4+ effector T cells with T21 are resistant to Treg-mediated suppression, regardless of Treg karyotype. Transcriptome analysis of white blood cells and T cells reveals strong signatures of T cell differentiation and activation that correlate positively with IFN hyperactivity. Finally, mass cytometry analysis of 8 IFN-inducible phosphoepitopes demonstrates that T cell subsets with T21 show elevated levels of basal IFN signaling and hypersensitivity to IFN-α stimulation. Therefore, these results point to T cell dysregulation associated with IFN hyperactivity as a contributor to autoimmunity in DS.