Overactive bladder in adults with sickle cell disease

Enuresis and overactive bladder in sickle cell patients: a narrative review of the literature

OBJECTIVE

The aim of this review is to clarify the prevalence, pathophysiology and clinical presentation of enuresis and overactive bladder in sickle cell patients.

MATERIALS AND METHODS

This narrative review of the literature was conducted in March 2022 by running a search in PubMed, Embase, Scopus and Cochrane databases without publication date limitation, using the following keywords: enuresis or nocturia or overactive bladder or urinary incontinence or bedwetting and sickle cell.

RESULTS

Eight cross-sectional studies were included, six of which had a non-sickle cell control population. The prevalence of enuresis in children and adolescents with sickle cell disease ranged from 20.3 to 49.4%. It decreased with age to 2.9% in adult sickle cell patients. Enuresis in sickle cell patients has been attributed to several causes, including lack of urine concentration with nocturnal polyuria, reduced bladder capacity, nocturnal bladder hyperactivity, sleep and/or respiratory disorders are likely causes of enuresis in sickle cell patients. The prevalence of overactive bladder is three times higher in sickle cell patients than in control groups. The latter is also observed three times more frequently in men who have had prior episodes of priapism.

CONCLUSION

Enuresis and overactive bladder are common in sickle cell patients. Several mechanisms have been described to try to explain enuresis in sickle cell patients but overactive bladder seems to play a major role. Studies evaluating the efficacy of certain experimentally validated treatments must be carried out to improve the management of these complications which affect the quality of life of sickle cell patients.

NO-Releasing Nanoparticles Ameliorate Detrusor Overactivity in Transgenic Sickle Cell Mice via Restored NO/ROCK Signaling

Sickle cell disease (SCD) is associated with overactive bladder (OAB). Detrusor overactivity, a component of OAB, is present in an SCD mouse, but the molecular mechanisms for this condition are not well-defined. We hypothesize that nitric oxide (NO)/ ras homolog gene family (Rho) A/Rho-associated kinase (ROCK) dysregulation is a mechanism for detrusor overactivity and that NO-releasing nanoparticles (NO-nps), a novel NO delivery system, may serve to treat this condition. Male adult SCD transgenic, combined endothelial NO synthases (eNOSs) and neuronal NOS (nNOS) gene-deficient (dNOS^-/-), and wild-type (WT) mice were used. Empty nanoparticle or NO-np was injected into the bladder, followed by cystometric studies. The expression levels of phosphorylated eNOS (Ser-1177), protein kinase B (Akt) (Ser-473), nNOS (Ser-1412), and myosin phosphatase target subunit 1 (MYPT1) (Thr-696) were assessed in the bladder. SCD and dNOS^-/- mice had a greater (P < 0.05) number of voiding and nonvoiding contractions compared with WT mice, and they were normalized by NO-np treatment. eNOS (Ser-1177) and AKT (Ser-473) phosphorylation were decreased (P < 0.05) in the bladder of SCD compared with WT mice and reversed by NO-np. Phosphorylated MYPT1, a marker of the RhoA/ROCK pathway, was increased (P < 0.05) in the bladder of SCD mice compared with WT and reversed by NO-np. nNOS phosphorylation on positive (Ser-1412) regulatory site was decreased (P < 0.05) in the bladder of SCD mice compared with WT and was not affected by NO-np. NO-nps did not affect any of the measured parameters in WT mice. In conclusion, dysregulation of NO and RhoA/ROCK pathways is associated with detrusor overactivity in SCD mice; NO-np reverses these molecular derangements in the bladder and decreases detrusor overactivity. SIGNIFICANCE STATEMENT: Voiding abnormalities commonly affect patients with sickle cell disease (SCD) but are problematic to treat. Clarification of the science for this condition in an animal model of SCD may lead to improved interventions for it. Our findings suggest that novel topical delivery of a vasorelaxant agent nitric oxide into the bladder of these mice corrects overactive bladder by improving deranged bladder physiology regulatory signaling.

Dysregulated NO/PDE5 signaling in the sickle cell mouse lower urinary tract: Reversal by oral nitrate therapy

AIMS

Nitric oxide (NO) has a critical, but not well understood, influence in the physiology of the lower urinary tract. We evaluated the effect of NO/phosphodiesterase (PDE)5 signaling in voiding dysfunction in the sickle cell disease (SCD) mouse, characterized by low NO bioavailability.

MAIN METHODS

Adult SCD (Sickle) and wild-type (WT) male mice were treated daily with sodium nitrate (10 mM) or vehicle. After 18 days, blood was obtained for nitrite measurement, urethra was collected for organ bath study, and bladder and urethra were collected for Western blot analysis of PDE5 phosphorylation (Ser-92) (activated form). Non-anesthetized mice underwent evaluation of urine volume by void spot assay. eNOS phosphorylation (Ser-1177) and nNOS phosphorylation (Ser-1412) (positive regulatory sites) were evaluated in the bladder and urethra of untreated mice.

KEY FINDINGS

Sickle mice exhibited decreased eNOS, nNOS, and PDE5 phosphorylation in the bladder and urethra, decreased plasma nitrite levels, increased relaxation of phenylephrine-contracted urethral tissue to an NO donor sodium nitroprusside, and increased total urine volume, compared with WT mice. Nitrate treatment normalized plasma nitrite levels, relaxation of urethra to sodium nitroprusside, PDE5 phosphorylation in the urethra and bladder, and urine volume in Sickle mice.

SIGNIFICANCE

Derangement in PDE5 activity associated with basally low NO bioavailability in the bladder and urethra contributes to the molecular basis for voiding abnormalities in Sickle mice. Inorganic nitrate supplementation normalized voiding in Sickle mice through mechanisms likely involving upregulation of PDE5 activity. These findings suggest that interventions targeting dysregulatory NO/PDE5 signaling may ameliorate overactive bladder in SCD.

Urinary dysfunction in transgenic sickle cell mice: model of idiopathic overactive bladder syndrome

Voiding abnormalities are common among the sickle cell disease (SCD) population, among which overactive bladder (OAB) syndrome is observed at rates as high as 39%. Although detrusor overactivity is the most common cause of OAB, its molecular pathophysiology is not well elucidated. The nitric oxide (NO) signaling pathway has been implicated in the regulation of lower genitourinary tract function. In the present study, we evaluated the role of the NO signaling pathway in voiding function of transgenic SCD mice compared with combined endothelial and neuronal NO synthase gene-deficient mice, both serving as models of NO deficiency. Mice underwent void spot assay and cystometry, and bladder and urethral specimens were studied using in vitro tissue myography. Both mouse models exhibited increased void volumes; increased nonvoiding and voiding contraction frequencies; decreased bladder compliance; increased detrusor smooth muscle contraction responses to electrical field stimulation, KCl, and carbachol; and increased urethral smooth muscle relaxation responses to sodium nitroprusside compared with WT mice. In conclusion, our comprehensive behavioral and functional study of the SCD mouse lower genitourinary tract, in correlation with that of the NO-deficient mouse, reveals NO effector actions in voiding function and suggests that NO signaling derangements are associated with an OAB phenotype. These findings may allow further study of molecular targets for the characterization and evaluation of OAB.

Enuresis in children and adolescents with sickle cell anaemia is more frequent and substantially different from the general population

Background

No large studies have examined the prevalence of enuresis, its various forms and risk factors in children with sickle cell anaemia (SCA) in Sub-Saharan Africa using standardised definitions. We determined age and gender-specific prevalence of enuresis and compared the nature of enuresis in children with and without SCA. We also identified predictors of enuresis in children with SCA.

Methods

Caregivers of children with SCA attending a tertiary centre haematology clinic in Nigeria were interviewed using a questionnaire. In addition, a separate questionnaire was completed for every sibling aged 5–17 years whose haemoglobin genotype was known. Enuresis and its various forms were defined using the definitions of the International Children’s Continence Society.

Results

The study involved 243 children with SCA and 243 controls matched for age and sex. The mean age of the study cohort was 9.9 (3.4). Females made up 45.7% of the cohorts. The prevalence of enuresis was 49.4% and 29.6% in children with and without SCA, respectively (p = 0.009). In both groups, the prevalence of enuresis declined with age but remained five times higher at 25% in children with SCA aged 14–17 years compared with controls. Also, children with SCA and enuresis were older, more likely to have non-monosymptomatic enuresis and wet at least three nights per week than controls. Independent predictors of enuresis in children with SCA were a family history of enuresis and young age.

Conclusion

Children with SCA had more frequent and more severe enuresis which persisted to late adolescence than age and sex-matched controls. These features indicate a subset of enuresis that is difficult to treat in the general population. Young age and enuresis in a family member define a subset of children with SCA more likely to have enuresis. Healthcare workers need to discuss enuresis with parents of children with SCA and offer referral to continence services.

The spectrum of sickle hemoglobin-related nephropathy: from sickle cell disease to sickle trait

INTRODUCTION

Renal dysfunction is among the most common complication of sickle cell disease (SCD), from hyposthenuria in children to progression to overt chronic kidney disease (CKD) in young adults. Emerging evidence now suggests that sickle hemoglobin-related nephropathy extends to individuals with sickle cell trait (SCT). Areas covered: This review will highlight the pathophysiology, epidemiology, and management recommendations for sickle hemoglobin-related nephropathy in both SCD and SCT. In addition, it will focus on the major demographic and genetic modifiers of renal disease in sickling hemoglobinopathies. Expert commentary: Studies have elucidated the course of renal disease in SCD; however, the scope and age of onset of renal dysfunction in SCT has yet to be determined. In SCD, several modifiers of renal disease - such as α-thalassemia, hemoglobin F, APOL1 and HMOX1 - have been described and provide an opportunity for a precision medicine approach to risk stratify patients who may benefit from early intervention. Extrapolating from this literature may also provide insight into the modifiers of renal disease in SCT. Further studies are needed to determine the optimal treatment for sickle hemoglobin-related nephropathy.

Urinary Bladder Dysfunction in Transgenic Sickle Cell Disease Mice

Background

Urological complications associated with sickle cell disease (SCD), include nocturia, enuresis, urinary infections and urinary incontinence. However, scientific evidence to ascertain the underlying cause of the lower urinary tract symptoms in SCD is lacking.

Objective

Thus, the aim of this study was to evaluate urinary function, in vivo and ex vivo, in the Berkeley SCD murine model (SS).

Methods

Urine output was measured in metabolic cage for both wild type and SS mice (25-30 g). Bladder strips and urethra rings were dissected free and mounted in organ baths. In isolated detrusor smooth muscle (DSM), relaxant response to mirabegron and isoproterenol (1nM-10μM) and contractile response to (carbachol (CCh; 1 nM-100μM), KCl (1 mM-300mM), CaCl₂ (1μM-100mM), α,β-methylene ATP (1, 3 and 10 μM) and electrical field stimulation (EFS; 1-32 Hz) were measured. Phenylephrine (Phe; 10nM-100μM) was used to evaluate the contraction mechanism in the urethra rings. Cystometry and histomorphometry were also performed in the urinary bladder.

Results

SS mice present a reduced urine output and incapacity to produce typical bladder contractions and bladder emptying (ex vivo), compared to control animals. In DSM, relaxation in response to a selective β3-adrenergic agonist (mirabegron) and to a non-selective β-adrenergic (isoproterenol) agonist were lower in SS mice. Additionally, carbachol, α, β-methylene ATP, KCl, extracellular Ca²⁺ and electrical-field stimulation promoted smaller bladder contractions in SS group. Urethra contraction induced by phenylephrine was markedly reduced in SS mice. Histological analyses of SS mice bladder revealed severe structural abnormalities, such as reductions in detrusor thickness and bladder volume, and cell infiltration.

Conclusions

Taken together, our data demonstrate, for the first time, that SS mice display features of urinary bladder dysfunction, leading to impairment in urinary continence, which may have an important role in the pathogenesis of the enuresis and infections observed the SCD patients.