Risdiplam improves subjective swallowing quality in non-ambulatory adult patients with 5q-spinal muscular atrophy despite advanced motor impairment

BACKGROUND

5q-associated spinal muscular atrophy (SMA) is characterized by the progressive loss of motor neurons with consecutive weakness and atrophy of the limb, respiratory, and bulbar muscles. While trunk and limb motor function improve or stabilize in adults with SMA under nusinersen and risdiplam treatment, the efficacy on bulbar function in this age group of patients remains uncertain. However, it is important to assess bulbar dysfunction, which frequently occurs in the disease course and is associated with increased morbidity and mortality.

METHODS

Bulbar function was evaluated prospectively in 25 non-ambulatory adults with type 2 and 3 SMA before and 4 and 12 months after risdiplam treatment initiation using the Sydney Swallow Questionnaire (SSQ) and the bulbar subscore of the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (b-ALSFRS-R). Extremity function was assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM).

RESULTS

Subjective swallowing quality, measured with the SSQ, improved after 12 months of therapy with risdiplam. For the b-ALSFRS-R, a non-significant trend towards improvement was observed. The RULM score improved after 12 months of risdiplam therapy, but not the HFMSE score. HFMSE and RULM scores did not correlate with the SSQ but the b-ALSFRS-R score at baseline.

CONCLUSIONS

The improvement in subjective swallowing quality under risdiplam treatment, despite an advanced disease stage with severe motor deficits, strengthens the importance of a standardized bulbar assessment in addition to established motor scores. This may reveal relevant treatment effects and help individualize treatment decisions in the future.

Objective measurement of oral function in adults with spinal muscular atrophy

BACKGROUND

Impairment of bulbar function in adult individuals with spinal muscular atrophy (SMA) usually is not assessed by established motor scores. Measurements of oral function including quantitative muscle and endurance tests are able to detect subtle changes. The aim of this study was to systematically evaluate the measurement of maximum bite force and endurance, maximum tongue pressure and endurance, as well as maximum mouth opening in adult individuals with SMA types 2 and 3.

METHODS

Data from oral function tests in 43 individuals were analyzed. Differences in oral function between individuals with different SMA types and numbers of SMN2 copies were tested. Spearman´s rho correlations among oral function measures themselves as well as with established clinical outcome scales were analyzed.

RESULTS

The absolute maximum measures of oral function (maximum bite force, maximum tongue pressure, maximum mouth opening) were able to discriminate between individuals with different SMA types, individuals with a different number of SMN2 copies and with different walking abilities. The pairwise correlations of the absolute maximum measures of oral function were fair to moderate in size; the same was true for their correlations with the established motor scores. All correlations assessing endurance measures of oral function were weaker and statistically insignificant.

CONCLUSIONS

Among the oral function tests maximum tongue pressure and maximum mouth opening are particulary promising as clinical and sensitive outcome measures for clinical trials. Oral function tests may supplement existing motor scores, in particular concerning specific questions about bulbar function or in severely affected non-ambulatory individuals where mild (treatment-related) changes would otherwise remain undetected. Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/search/de/trial/DRKS00015842.

Treatment of renal angiomyolipoma in tuberous sclerosis complex (TSC) patients

In adult tuberous sclerosis complex (TSC) patients, renal complications are the leading cause of death. Beginning in childhood, up to 80 % of patients develop renal angiomyolipoma characterized by a size-dependent risk of life-threatening bleeding. After discovery of the two causative genes, TSC1 and TSC2, and the role of mammalian target of rapamycin (mTOR) regulation in the pathogenesis of TSC, an increasing number of clinical studies evaluating mTOR inhibition in TSC patients have shown impressive results in many organ manifestations, such as brain, lung, and kidney. For renal angiomyolipoma, mTOR inhibitor treatment fundamentally changed the approach from preventive embolization or even partial nephrectomy to everolimus treatment in order to preserve kidney function.

Successful Recovery of Acute Renal Transplant Failure in Recurrent Hepatitis C Virus-Associated Membranoproliferative Glomerulonephritis

Recurrence of hepatitis C virus (HCV)-associated membranoproliferative glomerulonephritis (MPGN) in the kidney transplant may lead to continuous graft deterioration and the need for further renal replacement therapy. The novel direct-acting antiviral agents (DAAs) allow a highly effective and interferon-free treatment option for chronic HCV-infected patients. Data on the therapeutic safety and efficacy in HCV-infected renal transplant patients are sparse, especially for patients with severe renal impairment. We report the case of a 63-year-old female HCV-positive renal transplant patient with biopsy-proven recurrence of MPGN in the renal graft 3 years after transplant. Because of rapid loss of transplant function and consecutive need for hemodialysis, we initiated a combined anti-HCV-directed therapy regimen consisting of daclatasvir and simeprevir over 12 weeks. Viral clearance of HCV was obtained as early as 2 weeks after start of treatment. No adverse therapy-associated side effects were observed, and immunosuppressive dosing remained unchanged. Importantly, graft function fully recovered and hemodialysis was stopped 2 mo after the end of daclatasvir/simeprevir treatment. We report the first case of successful recovery of dialysis-dependent renal transplant failure after treatment of recurrent HCV-associated MPGN in a kidney transplant recipient by curing the underlying HCV infection with a combination of novel DAAs.

[Immunosuppression and its use in kidney transplantation]

BACKGROUND

Current immunosuppressive protocols effectively prevent acute rejection of renal allografts. Extensive drug toxicity and the deleterious effects of long-term immunosuppression are associated with significant morbidity and mortality.

OBJECTIVES

The purpose of this article is to provide an overview over modern immunosuppressants and their unwanted side effects and to discuss strategies for improved long-term transplant survival.

METHODS

Review of the current topic-related literature and discussion of our own experience.

RESULTS

The use of antibody induction together with an initial combination therapy of calcineurin inhibitors, mycophenolate and steroids is recommended and results in excellent early outcomes. Detrimental effects include an increased incidence of infections, malignomas, and cardiovascular diseases. Long-term transplant survival is impaired by extensive drug toxicity and the frequent development of donor specific antibodies. Reduction of overall cumulative exposure to immunosuppressants or the reduction of specific toxic drugs such as calcineurin inhibitors and steroids may improve long-term results. Alternative immunosuppressants like mTOR inhibitors and belatacept appear to be effective and safe but their long-term effects on patient and allograft survival needs to be established in clinical trials.

CONCLUSIONS

Current immunosuppressants provide effective protection from renal allograft rejection. However, their use is complicated by serious side effects. In the future, development of novel immunosuppressants and optimization of minimization strategies may help to improve long-term success after kidney transplantation.

Living Donor Transplantation: Long-Term Evolution Related to Age Matching

The lack of donors is favoring living kidney donor (LKD) transplantation worldwide, quite often beyond the classic age-matching rules. We analysed renal function (RF) at 1 and 5 years in all donor and recipients as well as death-censored graft and patient survival. LKD recipients were divided into 4 subgroups: young recipients-young donors (YR-YD; N = 355), elderly recipients-young donors (ER-YD; N = 13), young recipients-elderly donors (YR-ED; N = 67), and elderly recipients-elderly donors (ER-ED; N = 38). "Elderly" was defined as ≥60 years. RF was better in those who received a young allograft (YR-YD/ER-YD) at any time (P < .001). There was a trend toward higher proteinuria among the recipients of an old allograft (YR-ED/ER-ED) at any time (P = not significant [NS]). However, our population showed low levels of proteinuria and this was not a risk factor for graft failure. Logistic regression model showed that creatinine level at 1 year is a good predictor of graft losses. Graft survival was worse in the allografts from elderly donors (P < .001). Analysing the young recipients, renal survival was inferior in those who received an old kidney (YR-ED; P < .00005) as well as mortality rates at 14 years (P = .03). The RF of young (N = 295) and elderly donors (N = 98) was optimal with no progression to ESRD or deaths registered during follow-up. In conclusion, young recipients of elderly kidneys pay the price of a worse RF, allograft prognosis, and patient prognosis. The pair YR-ED is a doable option, but we recommend age matching when it is possible.

Donor-specific HLA antibodies in a cohort comparing everolimus with cyclosporine after kidney transplantation

Donor-specific HLA antibodies (DSA) have a negative impact on kidney graft survival. Therefore, we analyzed the occurrence of DSA and antibody-mediated rejection (AMR) in patients from two prospective randomized trials in our center. At 3-4.5 months posttransplant 127 patients were randomized to continue cyclosporine or converted to everolimus therapy. The presence of DSA was prospectively assessed using Luminex assays. AMR was defined according to the Banff 2009 classification. Antibody screening was available in 126 patients with a median follow-up of 1059 days. Seven out of 65 (10.8%) patients on cyclosporine developed DSA after a median of 991 days. In comparison, 14/61 patients (23.0%) randomized to everolimus developed DSA after 551 days (log-rank: p = 0.048). Eight patients on everolimus compared to two patients on cyclosporine developed AMR (log-rank: p = 0.036). Four of 10 patients with AMR-all in the everolimus group-lost their graft. A multivariate regression model revealed everolimus, >3 mismatches and living donor as significant risk factors for DSA. Acute rejection within the first year, >3 mismatches, everolimus and living donor were independent risk factors for AMR. This single center analysis demonstrates for the first time that everolimus-based immunosuppression is associated with an increased risk for the development of DSA and AMR.

Dent’s disease: identification of a novel mutation in the renal chloride channel CLCN5

Dent's disease is an inherited tubulopathy caused by a mutation in the CLCN5 chloride channel gene. It is characterized by low-molecular weight proteinuria, hypercalciuria, nephrolithiasis or nephrocalcinosis, rickets and eventual-progressive renal failure. Onset of clinical symptoms show a great variability, making a diagnosis at an early stage of the disease often difficult. Given the variably clinical picture, genetic analysis can provide a reliable method to confirm the diagnosis. Here, we report on the case of a patient with progressive renal failure showing signs of a tubular lesion and symptoms of Dent's disease. Although this rare disease was suspected by means of the clinical features, it was genetic analysis that confirmed the diagnosis and revealed a novel mutation in the CLCN5 gene.

Impaired hyperpolarization in regenerated endothelium after balloon catheter injury

Ca(2+)-activated K(+) (K(Ca)) channels control endothelial Ca(2+) homeostasis and the formation of vasodilators. After angioplasty, dysfunction of the regenerated endothelium leads to abnormal vasoregulation. In this study, we tested the expression and function of K(Ca) channels in regenerated endothelium at 6 weeks after balloon catheter injury of rat carotid arteries (CAs) by using single-cell reverse transcription-polymerase chain reaction, patch-clamp techniques, and analysis of vasoreactivity. In single regenerated endothelial cells (ECs), the percentage of ECs expressing the K(Ca) genes, rSK3 (12+/-8%) and rIK1 (22+/-9%), was significantly lower compared with the percentage of native ECs expressing these genes (rSK3 58+/-8%, rIK1 64+/-10%). In patch-clamp experiments, K(Ca) currents and acetylcholine-induced hyperpolarization were markedly reduced in regenerated ECs (shift of membrane potential -6+/-3 mV) compared with those in native ECs (shift of membrane potential -21+/-5 mV). In pressure myograph experiments, acetylcholine-induced dilation was impaired in reendothelialized CAs compared with normal CAs. Intraluminal application of the K(Ca) blocker apamin and charybdotoxin inhibited dilation by 30% in normal CAs but was without effect in reendothelialized CAs. Intraluminal application of 1-ethyl-2-benzimidazolinone (100 micromol/L), an opener of K(Ca) channels, evoked dilation by 29% in normal CAs but had no effect in reendothelialized CAs. In conclusion, the impaired expression of K(Ca) channels in regenerated endothelium results in defective hyperpolarization and impaired dilation. Thus, the impaired K(Ca) channel function contributes to functional alterations of regenerated endothelium after angioplasty.

Regulation of pressure-activated channel in intact vascular endothelium of stroke-prone spontaneously hypertensive rats

The pressure-activated cation channel (PAC), a novel type of mechanosensitive channel, has been suggested to act as a mechanosensor in aortic endothelium. In experimental hypertension, PAC function was up-regulated in the established phase of high blood pressure. This association of altered PAC function and elevated arterial pressure suggests that PAC function is regulated by alterations in blood pressure. In the present study, we electrophysiologically investigated PAC function in intact endothelium of aorta (EA) and mesenteric artery (EMA) from stroke-prone spontaneously hypertensive rats (SHRSP), SHRSP after 4 weeks of treatment with quinaprilat (10 mg/kg/day), and normotensive Wistar-Kyoto (WKY) rats. In untreated SHRSP and WKY rats, systolic blood pressure (SBP) was 201+/-3 mm Hg and 142+/-3 mm Hg, respectively. In quinaprilat-treated SHRSP, SBP was lowered to 135+/-5 mm Hg. Apparent PAC density (percentage of patches with PAC activity) in EA of untreated SHRSP (63.7%+/-7.3%) was 2.4-fold higher than in WKY rats (26.0%+/-5.0%). In contrast, no significant PAC up-regulation was detected in EMA of SHRSP (15.7%+/-4.2%) compared with WKY rats (12.0%+/-3.9%). In EA of quinaprilat-treated normotensive SHRSP, PAC density (27.1%+/-5.2%) was lowered to levels found in normotensive WKY rats. Unitary conductance and pressure sensitivity of PAC were not altered in either hypertensive or normotensive rats. Taken together, hypertension-induced increases of endothelial PAC density can be completely reversed by antihypertensive therapy. The PAC up-regulation in EA was interpreted as a compensatory mechanism to enhance Ca2+-influx and subsequently the synthesis of vasodilatory factors. This mechanism is missing in EMA of SHRSP, which might contribute to high blood pressure in this rat model of severe genetic hypertension.

Expression of ryanodine receptor type 3 and TRP channels in endothelial cells: comparison of in situ and cultured human endothelial cells

OBJECTIVE

Ca(2+) mobilization plays an important role in endothelial function by stimulating Ca(2+)-dependent synthesis of vasodilating factors. In addition to inositol-1,4,5-trisphosphate (InsP(3)) mediated Ca(2+) mobilization, Ca(2+) release from ryanodine-sensitive pools and Ca(2+)-influx through TRP channels have been suggested to be important in endothelial Ca(2+)-signaling. However, the function and molecular identity of TRP channels and ryanodine receptors in human endothelium in situ are still elusive. We hypothesized that expression of ryanodine-receptors (RyR) and TRP channels differs between human endothelium in situ and in cultured cells.

METHODS

By combining single-cell RT-PCR and patch-clamp techniques, expression of RyR and TRP channels was determined in situ in endothelial cells of human mesenteric artery (HMAECs) obtained from patients undergoing bowel resection and in the endothelial cell line EA.hy926.

RESULTS

At the single cell level, expression of RyR 3 was detected in 25 and 5% of HMAECs and EA.hy926 samples, respectively. Expression of the RyR 1 and 2 was not detected in either HMAECs or EA.hy926. In patch-clamp experiments in HMAECs, applications of caffeine (0.5 mM) induced sustained hyperpolarization mediated by activation of Ca(2+)-activated K channels. In EA.hy926, caffeine-induced hyperpolarization was not detected. Single HMAECs expressed the TRP genes, TRP1 and TRP3, but not TRP 4 and 6. The TRP1 was the predominantly expressed TRP gene in HMAECs in situ whereas TRP3 expression was rarely detected. EA.hy926 expressed only TRP1. In patch clamp experiments in HMAECs, Ca(2+)-store depletion activated non-selective cation currents leading to Ca(2+) entry.

CONCLUSIONS

Our findings suggest that, in addition to InsP(3) mediated Ca(2+) release, Ca(2+) release from ryanodine-sensitive stores mediated by RyR3 and Ca(2+) entry through TRP1 might represent important components of endothelial Ca(2+) signaling in situ and thereby of endothelial function in intact human blood vessels.