Failure In Early Adulthood Research Articles

Abstract 522: Impaired Inside-out Force Transmission in Hipsc-cardiomyocyte Model of Duchenne Muscular Dystrophy Cardiomyopathy

Duchenne Muscular Dystrophy (DMD) is a lethal X-chromosome linked disease that affects ~1:3500 boys and culminates in heart failure in early adulthood. DMD results from >200 possible dystrophin mutations. The lack of dystrophin disrupts the anchoring of the sarcomere to the extracellular matrix (ECM), impairing cardiomyocyte function and cardiac contraction. With disease progression, the heart tissue stiffness increases as fibrosis progresses and a dilated cardiomyopathy phenotype develops. We hypothesize that disease progression accelerates because of a positive feedback loop involving fibrotic stiffening and mechanosensing. Our preliminary results show that single human-derived pluripotent stem cell (hiPSC) cardiomyocytes (CMs) with DMD mutations have a dramatically reduced ability to produce force compared to isogenic controls on stiffer substrates mimicking a fibrotic state, but not on soft healthy substrates. This stiffness-dependent contractile deficiency correlates with an increase in reactive oxygen species (ROS) and mitochondrial dysfunction, as well as other markers of cellular stress response and senescence. Here, we ask how stiffness affects the progression of DMD cardiomyopathy and aim to draw a link between the lack of dystrophin and force production deficiency in hiPSC-CMs with or without DMD mutations in an isogenic background. Using a novel assay and algorithm, we simultaneously measure extracellular force production by traction force microscopy (TFM) and single sarcomere dynamics (SSD) in single hiPSC-CMs adhered onto ECM micropatterns on top of a hydrogel of stiffness matching that of healthy (~10kPa) or fibrotic (~35kPa) tissue. We induce the single hiPSC-CMs to adopt a physiologic elongated 1:7 aspect ratio using microcontact printing of ECM protein. Using this platform, we determine how the lack of dystrophin impacts sarcomere architecture, sarcomere contractility, and force generation in the etiology of DMD cardiac disease.

Abstract 211: Substrate Elasticity Impacts Duchenne Muscular Dystrophy Cardiomyopathy Progression

Duchenne Muscular Dystrophy (DMD) is a X-link disease affecting ~1:3500 boys per year and culminating with heart failure in early adulthood. DMD results from >200 possible genetic mutations on dystrophin. The lack of dystrophin disrupts the anchoring of the cell sarcomere to the extracellular matrix (ECM), affecting the cardiac contraction. With disease progression, in an attempt to mitigate the subcellular defects, the tissue stiffness and ECM composition remodel in association with a dilated cardiomyopathy phenotype and fibrosis. Our hypothesis is that disease progression is accelerating because of this remodelling, through a positive feedback loop involving multiple mechanosensing pathways. Here, we use a single-cell assay platform to model the effect of fibrotic remodelling in DMD. This platform allows measuring the force production of single human-derived pluripotent stem cell (hiPSC) cardiomyocytes (CMs). The substrate stiffness can be controlled to match that of healthy (~10kPa) or fibrotic (~35kPa) tissue. In addition, single iPSC-CMs are patterned in an elongated 1:7 aspect ratio using microcontact printing of ECM protein. This enhances their intracellular structural maturity towards a more mature adult phenotype. This renders our in-vitro model more representative of the human pathology and greatly improves our measurements standardization. Our results show that single iPSC-CMs with DMD mutations have a dramatically reduced ability to produce force on stiffer substrates compared to their isogenic control. This loss of contractile function correlates with an increase in reactive oxygen species (ROS) and mitochondria dysfunction, as well as with other markers of stress response and cellular senescence.We are asking how the remodeling of the ECM stiffness and composition is signaled from the outside-in and affects the progression of the disease phenotype. The further development of our platform and approach will allow for more accurate in-vitro modeling of cardiac diseases and greatly increase our understanding of the underlying biophysics of mechanosensing.

A Holistic Approach to Risk for Early Kidney Injury in Indigenous Youth With Type 2 Diabetes: A Proof of Concept Paper From the iCARE Cohort.

Background:Indigenous youth with type 2 diabetes (T2D) are disproportionately affected by early onset albuminuria and are at high risk of kidney failure in early adulthood. Traditional biological approaches have failed to fully explain the renal morbidity seen in this population. The improving renal Complications in Adolescents with type 2 diabetes through REsearch cohort (iCARE) study was therefore designed in collaboration with patients, to more holistically evaluate risk factors for renal morbidity. We hypothesize that both biological factors and mental health influence renal outcomes, mediated via inflammatory pathways.Objective:The objective of this study was to evaluate the iCARE analytic framework which evaluates relationships between biological factors, mental health, inflammation, and albuminuria utilizing a structural equation modeling (SEM) approach.Methods:The first 187 youth with T2D (10-25 years) from the Manitoba iCARE cohort are presented here to evaluate our theoretical and analytic framework. An SEM was chosen to evaluate the statistical significance of proposed associations. The primary outcome was a nonorthostatic urine albumin:creatinine ratio ≥2 mg/mmol. Main exposures (ie, latent factors) included psychological health (distress, perceived stress, positive mental health and resilience), hypertension (24 hour monitored), and inflammatory markers (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], fibrinogen). Hemoglobin A1c (HbA1c) and duration of diabetes were covariates.Results:Within the initial cohort (median age = 15 years, duration of diabetes = 2.3 years, 66.8% female), 30.5% (n = 57) had nonorthostatic albuminuria (ALB), and the majority of ALB was persistent (confirmed in 2/3 samples over a 6-month period; n = 47). Youth with ALB had higher HbA1c (10.9% vs 8.9%; P < .001), more hypertension (94.2% vs 78·2%; P = .02), longer duration of diabetes (3.4 vs 2.4 years; P = .01), higher distress (9.2 vs 7.3; P = .02), and stress scores (28.7 vs 26.4; P = .03), and elevated inflammatory markers (CRP: 4.9 vs 3.1 mg/L; P = .01, fibrinogen: 3.7 vs 3.3 µmol/L; P = .02). Factors directly associated with ALB in the SEM were hypertension (0.28; P = .001), inflammation (0.41; P < .001), and HbA1c (0.50; P < .001). Psychological health was independently associated with inflammation (−0.20; P < .001) but not directly associated with ALB.Conclusions:Albuminuria is highly prevalent in Indigenous youth with T2D. This preliminary analysis supports a theoretical framework linking glycemic control, hypertension, and inflammation, potentially mediated by psychological factors with albuminuria. These data support the need for more holistic models of evaluation and care for youth with T2D and multifactorial interventions to prevent complications.

G165(P) The Impact of a Multi-Disciplinary Neuro-Respiratory Clinic on the Respiratory Monitoring of Children with Duchenne’s Muscular Dystrophy

AimsDuchenne’s muscular dystrophy (DMD) is a progressive degenerative muscular disorder that leads to respiratory failure in early adulthood. Our aim was to assess the impact of the development of a...

A 46,XY Female DSD Patient with Bilateral Gonadoblastoma, a Novel SRY Missense Mutation Combined with a WT1 KTS Splice-Site Mutation

Patients with Disorders of Sex Development (DSD), especially those with gonadal dysgenesis and hypovirilization are at risk of developing malignant type II germ cell tumors/cancer (GCC) (seminoma/dysgerminoma and nonseminoma), with either carcinoma in situ (CIS) or gonadoblastoma (GB) as precursor lesion. In 10–15% of 46,XY gonadal dysgenesis cases (i.e., Swyer syndrome), SRY mutations, residing in the HMG (High Mobility Group) domain, are found to affect nuclear transport or binding to and bending of DNA. Frasier syndrome (FS) is characterized by gonadal dysgenesis with a high risk for development of GB as well as chronic renal failure in early adulthood, and is known to arise from a splice site mutation in intron 9 of the Wilms’ tumor 1 gene (WT1). Mutations in SRY as well as WT1 can lead to diminished expression and function of SRY, resulting in sub-optimal SOX9 expression, Sertoli cell formation and subsequent lack of proper testicular development. Embryonic germ cells residing in this unfavourable micro-environment have an increased risk for malignant transformation. Here a unique case of a phenotypically normal female (age 22 years) is reported, presenting with primary amenorrhoea, later diagnosed as hypergonadotropic hypogonadism on the basis of 46,XY gonadal dygenesis with a novel missense mutation in SRY. Functional in vitro studies showed no convincing protein malfunctioning. Laparoscopic examination revealed streak ovaries and a normal, but small, uterus. Pathological examination demonstrated bilateral GB and dysgerminoma, confirmed by immunohistochemistry. Occurrence of a delayed progressive kidney failure (focal segmental glomerular sclerosis) triggered analysis of WT1, revealing a pathogenic splice–site mutation in intron 9. Analysis of the SRY gene in an additional five FS cases did not reveal any mutations. The case presented shows the importance of multi-gene based diagnosis of DSD patients, allowing early diagnosis and treatment, thus preventing putative development of an invasive cancer.

Urine biomarkers in juvenile-onset SLE nephritis

Over 80 % of patients with juvenile-onset systemic lupus erythematosus will have renal involvement compared to 40 % with adult-onset disease. Up to 44 % of children who do have lupus nephritis (LN) progress to renal failure in early adulthood. Improved methods of detecting onset of LN would allow earlier treatment, which may prevent irreversible renal scarring and a decline in renal function. Current conventional markers of disease activity fail to adequately predict renal lupus flares and include proteinuria, complement levels, anti-double-stranded DNA antibodies and serum creatinine concentrations. Standardized histological classification is currently the gold standard for diagnosing and classifying LN, but its invasive nature limits routine use for monitoring, especially in a childhood population. Novel biomarkers need to be sensitive and specific-and preferably non-invasive and cost-effective. The most promising biomarkers in juvenile-onset LN include urinary neutrophil gelatinase associated lipocalin, monocyte chemoattractant protein 1 and transforming growth factor-beta, although many others have been identified and are under investigation. No one biomarker yet discovered is unique to LN, indicating an overlap in disease pathophysiology. It is likely that a combination of biomarkers will be required for assessing disease flare detection, response to treatment and prognostic information. Potential biomarkers require longitudinal validation in large paediatric, prospective cohorts to assess their ability to act as clinically useful adjuncts.

Stony kidneys in a child: Clue to a rare diagnosis

alanine-glyoxalate transaminase. Type 2 is caused by the deficiency of cytosolic enzymes glyoxalate reductase and D-glycerate dehydrogenase. Type 3 results from a primary increase in the absorption of oxalate from the gastrointestinal tract.Classic presentation is nephrocalcinosis with nephrolithiasis, which leads to renal failure in early adulthood. Once the kidneys fail, oxalate accumulates in the body and gets deposited at various sites. Preferred A five-year-old boy presented to the Emergency Department with altered sensorium. He had nausea, with occasional vomiting and anorexia for the past one week. His parents denied any history of fever, diarrhea or a significant past medical history or significant family history. The child was unconscious, afebrile, with a pulse rate of 68/minute, blood pressure of 140/80 mmHg and respiratory rate of 17/minute. The systemic examination was unremarkable.Urinalysis showed calcium oxalate crystals in abundance and blood investigations revealed elevated urea and creatinine levels. A twenty-four hour urinary oxalate was found to be elevated.Abdominal radiographs showed bilateral diffusely dense kidneys [Figure 1]. Ultrasonography revealed normal-sized kidneys with a smooth outline and uniformly raised cortical echogenicity. No calculus or hydronephrosis was present. Non-contrast computed tomography (NCCT) showed diffusely increased density of both the kidneys with calculi in the gall bladder [Figure 2]. Based on the findings of urinalysis and imaging characteristics, a diagnosis of primary hyperoxaluria was suspected and later confirmed on liver biopsy.Primary hyperoxaluria is a group of autosomal recessive disorders caused by deficient metabolism of glyoxalate to glycine, leading to an increased production of oxalate that gets deposited in various organs. At least three different types of hyperoxalurias are known.

Characteristics of testicular dysgenesis syndrome and decreased expression of SRY and SOX9 in Frasier syndrome

Frasier syndrome (FS) is characterized by chronic renal failure in early adulthood, varying degrees of gonadal dysgenesis, and a high risk for gonadal germ cell malignancies, particularly gonadoblastoma. Although it is known to arise from heterozygous splice mutations in intron 9 of the Wilms' tumor gene 1 (WT1), the mechanisms by which these mutations result in gonadal dysgenesis in humans remain obscure. Here we show that a decrease in WT1 + KTS isoforms due to disruption of alternative splicing of the WT1 gene in a FS patient is associated with diminished expression of the transcription factors SRY and SOX9 in Sertoli cells. These findings provide the first confirmation in humans of the results obtained by others in mice. Consequently, Sertoli cells fail to form the specialized environment within the seminiferous tubules that normally houses developing germ cells. Thus, germ cells are unable to fully mature and are blocked at the spermatogonial-spermatocyte stage. Concomitantly, subpopulations of the malignant counterpart of primordial germ cells/gonocytes, the intratubular germ cell neoplasia unclassified type (ITGCN), are identified. Furthermore, dysregulated Leydig cells produce insufficient levels of testosterone, resulting in hypospadias. Collectively, the impaired spermatogenesis, hypospadias and ITGCN comprise part of the developmental disorder known as 'testicular dysgenesis syndrome' (TDS), which arises during early fetal life. The data presented here show that critical levels of WT1 + KTS, SRY and SOX9 are required for normal Sertoli cell maturation, and subsequent normal spermatogenesis. To further study the function of human Sertoli cells in the future, we have established a human cell line.

Adolescent urology: A challenge for adult urologists

The medical care of adolescents has become a growth area in many disciplines. There are two major aspects. Firstly, adolescents have specific medical and emotional needs which are not fulfilled either by paediatric or by adult specialists. Secondly, some childhood problems, particularly the congenital deformities, have no equivalent in adult life and so lifelong care is mandatory. Renal damage, especially dysplasia and scarring, leads to a substantial risk of early onset hypertension and, occasionally, to renal failure. Bladder outlet obstruction in utero, such as from a posterior urethral valve, causes irreversible changes to the wall that will act adversely on the kidneys in adolescence or early adulthood. The incidence of renal failure in early adulthood is about 36%. Bladder reconstruction with bowel has been very beneficial in preventing renal failure and improving continence. Life long follow-up is needed because of the high incidence of complications. These include stones, hyperchloraemic acidosis, perforation, anastomotic stenosis and, possibly, cancer. Patients have a normal expectation of sexuality and fertility. Their desires cannot always be achieved but they require considerable emotional and surgical support.

Role of truncating mutations in MME gene in fetomaternal alloimmunisation and antenatal glomerulopathies

Membranous glomerulonephritis is an immune-mediated disease. In a recent case of antenatal membranous glomerulonephritis, we identified neutral endopeptidase (NEP) as the podocyte target antigen of circulating antibodies produced by the mother who failed to express NEP on granulocytes. We aimed to investigate whether the disease could affect other families, to search for mutations in the metallomembrane endopeptidase (MME) gene for NEP, and to analyse the outcome of the antenatal renal insult. From three families with a case of neonatal membranous glomerulopathy, we detected mutations by direct sequencing of genomic PCR products. Single nucleotide polymorphism (SNP) analysis was undertaken with five SNPs located in the MME gene. IgG subclasses with anti-NEP activity were determined by western blotting. In five mothers, we identified two compound heterozygous or homozygous mutations in the MME gene. The first, a 1342C-->T nonsense mutation, was detected in one family. The second, 446delC, was detected in all three families; all chromosomes bearing this mutation had the same alleles for the five SNPs. Severity of neonatal renal disease was determined by the mothers' IgG response to fetal NEP antigens expressed on glomerular podocytes. The oldest affected individual, now aged 20 years, has developed severe chronic renal failure. Truncating mutations in the MME gene are the cause of alloimmunisation during pregnancy. Idiopathic renal failure in early adulthood might be caused by immune-mediated fetal nephron loss. We show that disease caused by fetomaternal alloimmunisation secondary to a genetic defect is not restricted to blood cells. During pregnancy, the absence of the NEP protein induces an alloimmunisation process against NEP presented by fetal cells, including syncytiotrophoblasts. The fetal podocyte insult and ensuing nephron loss could lead to chronic renal failure in early adulthood. Alloimmunisation against NEP should be considered as a leading cause of membranous glomerulopathy early in life. Concentrations of circulating anti-NEP antibodies should be carefully monitored during subsequent pregnancies, and specific therapeutic approaches developed. This new disease might also account for idiopathic chronic renal failure detected during adolescence, in individuals who can be identified by searching for anti-NEP antibodies in their mother and by MME gene mutation analysis. NEP deficiency should also be considered in patients developing de-novo membranous glomerulopathy after renal transplantation.