A homozygous missense variant in CHRM3 associated with familial urinary bladder disease

Human HPSE2 gene transfer ameliorates bladder pathophysiology in a mutant mouse model of urofacial syndrome

Rare early-onset lower urinary tract disorders include defects of functional maturation of the bladder. Current treatments do not target the primary pathobiology of these diseases. Some have a monogenic basis, such as urofacial, or Ochoa, syndrome (UFS). Here, the bladder does not empty fully because of incomplete relaxation of its outflow tract, and subsequent urosepsis can cause kidney failure. UFS is associated with biallelic variants of HPSE2, encoding heparanase-2. This protein is detected in pelvic ganglia, autonomic relay stations that innervate the bladder and control voiding. Bladder outflow tracts of Hpse2 mutant mice display impaired neurogenic relaxation. We hypothesized that HPSE2 gene transfer soon after birth would ameliorate this defect and explored an adeno-associated viral (AAV) vector-based approach. AAV9/HPSE2, carrying human HPSE2 driven by CAG, was administered intravenously into neonatal mice. In the third postnatal week, transgene transduction and expression were sought, and ex vivo myography was undertaken to measure bladder function. In mice administered AAV9/HPSE2, the viral genome was detected in pelvic ganglia. Human HPSE2 was expressed and heparanase-2 became detectable in pelvic ganglia of treated mutant mice. On autopsy, wild-type mice had empty bladders, whereas bladders were uniformly distended in mutant mice, a defect ameliorated by AAV9/HPSE2 treatment. Therapeutically, AAV9/HPSE2 significantly ameliorated impaired neurogenic relaxation of Hpse2 mutant bladder outflow tracts. Impaired neurogenic contractility of mutant detrusor smooth muscle was also significantly improved. These results constitute first steps towards curing UFS, a clinically devastating genetic disease featuring a bladder autonomic neuropathy.

Muscarinic control of cardiovascular function in humans: a review of current clinical evidence

PURPOSE

To review the available evidence on the impact of muscarinic receptor modulation on cardiovascular control in humans.

METHODS

In this narrative Review we summarize data on cardiovascular endpoints from clinical trials of novel subtype-selective or quasi-selective muscarinic modulators, mostly PAMs, performed in the last decade. We also review the cardiovascular phenotype in recently described human genetic and autoimmune disorders affecting muscarinic receptors.

RESULTS

Recent advancements in the development of compounds that selectively target muscarinic acetylcholine receptors are expanding our knowledge about the physiological function of each muscarinic receptor subtype (M1, M2, M3, M4, M5). Among these novel compounds, positive allosteric modulators (PAMs) have emerged as the preferred therapeutic to regulate muscarinic receptor subtype function. Many muscarinic allosteric and orthosteric modulators (including but not limited to xanomeline-trospium and emraclidine) are now in clinical development and approaching regulatory approval for multiple indications, including the treatment of cognitive and psychiatric symptoms in patients with schizophrenia as well as Alzheimer's disease and other dementias. The results of these clinical trials provide an opportunity to understand the influence of muscarinic modulation on cardiovascular autonomic control in humans. While the results and the impact of each of these therapies on heart rate and blood pressure control have been variable, in part because the clinical trials were not specifically designed to measure cardiovascular endpoints, the emerging data is valuable to elucidate the relative cardiovascular contributions of each muscarinic receptor subtype.

CONCLUSION

Understanding the muscarinic control of cardiovascular function is of paramount importance and may contribute to the development of novel therapeutic strategies for treating cardiovascular disease.

Expanding the HPSE2 Genotypic Spectrum in Urofacial Syndrome, A Disease Featuring a Peripheral Neuropathy of the Urinary Bladder

Urofacial (also called Ochoa) syndrome (UFS) is an autosomal recessive congenital disorder of the urinary bladder featuring voiding dysfunction and a grimace upon smiling. Biallelic variants in HPSE2, coding for the secreted protein heparanase-2, are described in around half of families genetically studied. Hpse2 mutant mice have aberrant bladder nerves. We sought to expand the genotypic spectrum of UFS and make insights into its pathobiology. Sanger sequencing, next generation sequencing and microarray analysis were performed in four previously unreported families with urinary tract disease and grimacing. In one, the proband had kidney failure and was homozygous for the previously described pathogenic variant c.429T>A, p.(Tyr143*). Three other families each carried a different novel HPSE2 variant. One had homozygous triplication of exons 8 and 9; another had homozygous deletion of exon 4; and another carried a novel c.419C>G variant encoding the missense p.Pro140Arg in trans with c.1099-1G>A, a previously reported pathogenic splice variant. Expressing the missense heparanase-2 variant in vitro showed that it was secreted as normal, suggesting that 140Arg has aberrant functionality after secretion. Bladder autonomic neurons emanate from pelvic ganglia where resident neural cell bodies derive from migrating neural crest cells. We demonstrated that, in normal human embryos, neuronal precursors near the developing hindgut and lower urinary tract were positive for both heparanase-2 and leucine rich repeats and immunoglobulin like domains 2 (LRIG2). Indeed, biallelic variants of LRIG2 have been implicated in rare UFS families. The study expands the genotypic spectrum in HPSE2 in UFS and supports a developmental neuronal pathobiology.

Biological evaluation of linalool on the function of blood vessels

Long-term hypertension leads to alterations in the structure and function of blood vessels, and abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are important factors for these changes. Linalool is a natural compound extracted from plants. The present study aimed to explore the role and underlying mechanism of linalool in the physiological behavior of VSMCs. Angiotensin II (Ang II) was utilized to treat VSMCs, and MTT and western blotting assays were then employed to detect the effect of linalool on the induced proliferation and migration of VSMCs. The target gene of linalool was predicted by the SwissTargetPrediction website, and its expression level in VSMCs was determined using reverse transcription-quantitative PCR and western blotting. Next, the role of the target gene in the physiological behavior of VSMCs treated with linalool was examined, and the signaling pathway was explored. The results revealed that the proliferation and migration of VSMCs treated with Ang II were significantly promoted, and linalool could alleviate these effects in a dose-dependent manner. Cholinergic receptor muscarinic 3 (CHRM3), as a predicted target, was found to be highly expressed in Ang II-induced VSMCs, and CHRM3 overexpression could prevent the inhibitory effect of linalool on cell proliferation and migration. In addition, its overexpression caused an increase in the expression of proteins related to the MAPK signaling pathway. In conclusion, linalool inhibited the proliferation and migration of Ang II-induced VSMCs and blocked the MAPK signaling pathway by downregulating CHRM3.

Envisioning treating genetically-defined urinary tract malformations with viral vector-mediated gene therapy

Human urinary tract malformations can cause dysfunctional voiding, urosepsis and kidney failure. Other affected individuals, with severe phenotypes on fetal ultrasound screening, undergo elective termination. Currently, there exist no specific treatments that target the primary biological disease mechanisms that generate these urinary tract malformations. Historically, the pathogenesis of human urinary tract malformations has been obscure. It is now established that some such individuals have defined monogenic causes for their disease. In health, the implicated genes are expressed in either differentiating urinary tract smooth muscle cells, urothelial cells or peripheral nerve cells supplying the bladder. The phenotypes arising from mutations of these genes include megabladder, congenital functional bladder outflow obstruction, and vesicoureteric reflux. We contend that these genetic and molecular insights can now inform the design of novel therapies involving viral vector-mediated gene transfer. Indeed, this technology is being used to treat individuals with early onset monogenic disease outside the urinary tract, such as spinal muscular atrophy. Moreover, it has been contended that human fetal gene therapy, which may be necessary to ameliorate developmental defects, could become a reality in the coming decades. We suggest that viral vector-mediated gene therapies should first be tested in existing mouse models with similar monogenic and anatomical aberrations as found in people with urinary tract malformations. Indeed, gene transfer protocols have been successfully pioneered in newborn and fetal mice to treat non-urinary tract diseases. If similar strategies were successful in animals with urinary tract malformations, this would pave the way for personalized and potentially curative treatments for people with urinary tract malformations.

Prune belly syndrome in Finland - A population-based study on current epidemiology and hospital admissions

BACKGROUND

Prune belly syndrome (PBS) is a multisystem disease characterized by absent or deficient abdominal musculature with accompanying lax skin, urinary tract abnormalities, and cryptorchidism. Previous studies have estimated a birth prevalence of 1 in 35,000-50,000 live births.

OBJECTIVE

We set out to clarify the epidemiology and early hospital admissions of PBS in Finland through a population-based register study. Further, possible maternal risk factors for PBS were analyzed in a case-control setting.

STUDY DESIGN

The Finnish Register of Congenital Malformations was linked to the Care Register for Health Care, a population-based hospital admission data for PBS patients. Additionally, five matched controls were identified in the Birth Register and maternal risk factors of PBS were studied utilizing data from the Drugs and Pregnancy database.

RESULTS

We identified 31 cases of PBS during 1993-2015, 15 of which were live born and 16 elective terminations. The total prevalence was 1 in 44,000 births. Three patients (20%) died during infancy. On average, PBS-patients had 3.2 admissions and 10.6 hospital days per year in Finland during the study period years 1998-2015, 35- and 27-fold compared to children in Finland in general. Multiple miscarriages were significantly associated to PBS in maternal risk factor analyses.

DISCUSSION

The burden of disease is significant in PBS, demonstrated as a high infant mortality rate (20%), multiple hospital admissions, and inpatient care in days. The available variables are limited as a register-based study.

CONCLUSION

We present data on contemporary epidemiology in a population-based study and show that the total prevalence of PBS is 1 in 44,000 in Finland. PBS entails a significant disease burden with admissions and hospital days over 35- and 27-fold compared to the general pediatric population, further aggravated by an infant mortality rate of 20%.

Principles and Practical Considerations for the Analysis of Disease-Associated Alternative Splicing Events Using the Gateway Cloning-Based Minigene Vectors pDESTsplice and pSpliceExpress

Splicing is an important RNA processing step. Genetic variations can alter the splicing process and thereby contribute to the development of various diseases. Alterations of the splicing pattern can be examined by gene expression analyses, by computational tools for predicting the effects of genetic variants on splicing, and by splicing reporter minigene assays for studying alternative splicing events under defined conditions. The minigene assay is based on transient transfection of cells with a vector containing a genomic region of interest cloned between two constitutive exons. Cloning can be accomplished by the use of restriction enzymes or by site-specific recombination using Gateway cloning. The vectors pDESTsplice and pSpliceExpress represent two minigene systems based on Gateway cloning, which are available through the Addgene plasmid repository. In this review, we describe the features of these two splicing reporter minigene systems. Moreover, we provide an overview of studies in which determinants of alternative splicing were investigated by using pDESTsplice or pSpliceExpress. The studies were reviewed with regard to the investigated splicing regulatory events and the experimental strategy to construct and perform a splicing reporter minigene assay. We further elaborate on how analyses on the regulation of RNA splicing offer promising prospects for gaining important insights into disease mechanisms.

The Urothelium: Life in a Liquid Environment

The urothelium, which lines the renal pelvis, ureters, urinary bladder, and proximal urethra, forms a high-resistance but adaptable barrier that surveils its mechanochemical environment and communicates changes to underlying tissues including afferent nerve fibers and the smooth muscle. The goal of this review is to summarize new insights into urothelial biology and function that have occurred in the past decade. After familiarizing the reader with key aspects of urothelial histology, we describe new insights into urothelial development and regeneration. This is followed by an extended discussion of urothelial barrier function, including information about the roles of the glycocalyx, ion and water transport, tight junctions, and the cellular and tissue shape changes and other adaptations that accompany expansion and contraction of the lower urinary tract. We also explore evidence that the urothelium can alter the water and solute composition of urine during normal physiology and in response to overdistension. We complete the review by providing an overview of our current knowledge about the urothelial environment, discussing the sensor and transducer functions of the urothelium, exploring the role of circadian rhythms in urothelial gene expression, and describing novel research tools that are likely to further advance our understanding of urothelial biology.

A homozygous missense variant in CHRM3 associated with familial urinary bladder disease

CHRM3 codes for the M3 muscarinic acetylcholine receptor that is located on the surface of smooth muscle cells of the detrusor, the muscle that effects urinary voiding. Previously, we reported brothers in a family affected by a congenital prune belly‐like syndrome with mydriasis due to homozygous CHRM3 frameshift variants. In this study, we describe two sisters with bladders that failed to empty completely and pupils that failed to constrict fully in response to light, who are homozygous for the missense CHRM3 variant c.352G > A; p.(Gly118Arg). Samples were not available for genotyping from their brother, who had a history of multiple urinary tract infections and underwent surgical bladder draining in the first year of life. He died at the age of 6 years. This is the first independent report of biallelic variants in CHRM3 in a family with a rare serious bladder disorder associated with mydriasis and provides important evidence of this association.