Monoclonal gammopathy of renal significance: An atypical presentation of Waldenström's disease

Waldenström's disease is a rare lymphoproliferative syndrome in the bone marrow and sometimes in lymphoid organs which secretes high amounts of monoclonal immunoglobulin M into serum. It can remain indolent for years and rarely affects the kidney, with intraglomerular rather than intratubular damage being predominant, in contrast to multiple myeloma. Different studies identified AL amyloidosis as the most frequent renal lesion, followed by cryoglobulinemic glomerulonephritis. Signs and symptoms may be unspecific, as well as renal manifestations, so collaboration between nephrologists, hematologists, and pathologists is crucial to establish the role of paraprotein in the development of renal damage. We present an atypical case of Waldenström's disease that had a minimal monoclonal peak and clinically debuted with nephritic and nephrotic syndromes. The diagnosis was cryoglobulinemic glomerulonephritis. Currently, there are numerous treatment options, without enough evidence yet to establish a standardised treatment.

Sodium-glucose cotransporter 2 inhibition in primary and secondary glomerulonephritis

BACKGROUND

The role of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in the management glomerular/systemic autoimmune diseases with proteinuria in real-world clinical settings is unclear.

METHODS

This is a retrospective, observational, international cohort study. Adult patients with biopsy-proven glomerular diseases were included. The main outcome was the percentage reduction in 24-h proteinuria from SGLT2i initiation to 3, 6, 9 and 12 months. Secondary outcomes included percentage change in estimated glomerular filtration rate (eGFR), proteinuria reduction by type of disease and reduction of proteinuria ≥30% from SGLT2i initiation.

RESULTS

Four-hundred and ninety-three patients with a median age of 55 years and background therapy with renin-angiotensin system blockers were included. Proteinuria from baseline changed by -35%, -41%, -45% and -48% at 3, 6, 9 and 12 months after SGLT2i initiation, while eGFR changed by -6%, -3%, -8% and -10.5% at 3, 6, 9 and 12 months, respectively. Results were similar irrespective of the underlying disease. A correlation was found between body mass index (BMI) and percentage proteinuria reduction at last follow-up. By mixed-effects logistic regression model, serum albumin at SGLT2i initiation emerged as a predictor of ≥30% proteinuria reduction (odds ratio for albumin <3.5 g/dL, 0.53; 95% CI 0.30-0.91; P = .02). A slower eGFR decline was observed in patients achieving a ≥30% proteinuria reduction: -3.7 versus -5.3 mL/min/1.73 m2/year (P = .001). The overall tolerance to SGLT2i was good.

CONCLUSIONS

The use of SGLT2i was associated with a significant reduction of proteinuria. This percentage change is greater in patients with higher BMI. Higher serum albumin at SGLT2i onset is associated with higher probability of achieving a ≥30% proteinuria reduction.

Trial design of the MOTheR HDx study: a multicenter, open-label, prospective, randomized study to explore the morbidity and mortality in patients dialyzed with the Theranova HDx in comparison with online hemodiafiltration

Background

Dialysis patients have been maintaining a high rate of cardiovascular morbidity and mortality. For this reason, it is to introduce necessary new technical advances in clinical practice. There is a relation between toxins retention and inflammation, mortality and morbidity. Medium cut-off (MCO) membranes are a new generation of membranes that allow the removal of a greater number of medium-sized molecules compared with high-flux hemodialysis (HF-HD), but retaining albumin. MCO membranes have an increased permeability and the presence of internal filtration. Because of these special properties, MCO generated a new concept of therapy called expanded HD (HDx). Until now, online hemodiafiltration (OL-HDF) has demonstrated its superiority, in terms of survival, compared with HF-HD. However, the comparison between OL-HDF and HDx remains an unsolved question.

Methods

The MOTheR HDx study trial (NCT03714386) is an open-label, multicenter, prospective, 1:1 randomized, parallel-group trial designed to evaluate the efficacy and safety of HDx compared with OL-HDF in patients treated for dialysis in Spain for up to 36 months. The main endpoint is to determinate whether HDx is non inferior to OL-HDF at reducing the combined outcome of all-cause death and stroke (ischemic or hemorrhagic), acute coronary syndrome (angina and myocardial infarction), peripheral arterial disease (amputation or revascularization) and ischemic colitis (mesenteric thrombosis).

Results

The trial has already started.

Comparison of 2 medium cutoff dialyzers versus on-line hemodiafiltration regarding depurative ability and albumin loss: An uncontrolled clinical research

BACKGROUND

Hemodialysis (HD) techniques that best remove molecules in the middle to high molecular weight range are on-line hemodiafiltration (OL-HDF) and HD with medium cut-off (MCO) membranes. The aim of this study was to compare efficacy and safety of OL-HDF with FxCordiax HDF 800™, with HD with 2 MCO dialyzers: Theranova 500® and the new Elisio 21HX™ dialyzer.

METHODS

Fourteen patients following treatment with OL-HDF using FxCordiax HDF 800™ were randomized to receive a consecutive 1-week HD treatment with Theranova 500® and Elisio 21HX™.The reduction rate (RR) of differently sized molecules was compared, as well as the variation rate in molecules smaller than 1000, detected by nuclear magnetic resonance based chemometrics (metabolomics). Albumin loss in dialysate was quantified.

RESULTS

Lower RRs were found for molecules around 20 000 with Elisio 21HX™ compared to OL- HDF (RR prolactin 58.5% versus 66.7%, p = 0.034; RR Kappa light chain 63.1% versus 71.8%, p = 0.010). Albumin loss per session was higher with Theranova 500® than with OL-HDF and with Elisio 21HX™ (2249.9 ± 714.1 mg, 815.2 ± 474.0 mg, 442.9 ± 135.9 mg, p < 0.001, respectively). Metabolomic studies suggested, by semi-quantitative analysis, a greater depurative capacity of OL-HDF, followed by Elisio 21HX™, and then Theranova 500®.

CONCLUSIONS

In this study, HD with Theranova 500® has proven to be very similar in efficacy to OL-HDF, although with a significantly higher albumin loss. HD with Elisio 21HX™ resulted in lower removal of molecules around 20 000 compared to OL-HDF, with no significant difference compared to Theranova 500®, and with less albumin loss than Theranova 500®.

Hyperphosphatemia-Induced Oxidant/Antioxidant Imbalance Impairs Vascular Relaxation and Induces Inflammation and Fibrosis in Old Mice

Aging impairs vascular function, but the mechanisms involved are unknown. The aim of this study was to analyze whether aging-related hyperphosphatemia is implied in this effect by elucidating the role of oxidative stress. C57BL6 mice that were aged 5 months (young) and 24 months (old), receiving a standard (0.6%) or low-phosphate (0.2%) diet, were used. Isolated mesenteric arteries from old mice showed diminished endothelium-dependent vascular relaxation by the down-regulation of NOS3 expression, increased inflammation and increased fibrosis in isolated aortas, compared to those isolated from young mice. In parallel, increased Nox4 expression and reduced Nrf2, Sod2-Mn and Gpx1 were found in the aortas from old mice, resulting in oxidant/antioxidant imbalance. The low-phosphate diet improved vascular function and oxidant/antioxidant balance in old mice. Mechanisms were analyzed in endothelial (EC) and vascular smooth muscle cells (SMCs) treated with the phosphate donor ß-glycerophosphate (BGP). In EC, BGP increased Nox4 expression and ROS production, which reduced NOS3 expression via NFκB. BGP also increased inflammation in EC. In SMC, BGP increased Collagen I and fibronectin expression by priming ROS production and NFκB activity. In conclusion, hyperphosphatemia reduced endothelium-dependent vascular relaxation and increased inflammation and vascular fibrosis through an impairment of oxidant/antioxidant balance in old mice. A low-phosphate diet achieved improvements in the vascular function in old mice.

Effective glutamate clearance from the systemic circulation by hemodialysis: Potential relevance for cerebral ischemia management

High glutamate levels after head trauma or cerebral ischemia have neurotoxic effects. The objective of the present study was to evaluate the efficacy of hemodialysis to remove glutamate from the blood and to assess the behavior of this small molecule. Ten patients with end-renal disease on hemodialysis were included in the study. Glutamate clearance was evaluated within the first hour of hemodialysis on a midweek dialysis day on five patients who underwent low flux hemodialysis, whereas the other five patients underwent highly efficient hemodialysis (high flux hemodialysis on one day and online hemodiafiltration on another day). Glutamate clearance with hemodialysis was very effective and did not show any differences between the techniques (low flux: 214 [55], high flux: 204 [37], online hemodiafiltration: 202 [16], median (interquartile range), P = .7). Glutamate clearance was almost equivalent to vascular access plasma flow and it was not affected by dialyzer permeability or ultrafiltration rate. After a hemodialysis session, a significant decrease in glutamate blood level was observed (prehemodialysis: 59.7 [36.1], posthemodialysis 37.0 [49.2], P = .005). Dialysis performed under fasting condition showed higher glutamate reduction rate (60%) than that under feeding condition (20%). Hemodialysis may be an effective method to reduce glutamate blood levels, and the molecule clearance does not differ between the different techniques used. Considering previous results in experimental models, hemodialysis without hemodynamic stress, could be considered for reducing glutamate neurotoxic effects in acute ischemic strokes of patients in chronic hemodialysis programs.

Recurrent postinfectious glomerulonephritis: an unusual evolution compatible with C3 glomerulopathy

Acute endocapillary glomerulonephritis, as its name suggests, is a one-time process, which usually resolves within weeks. However, in a small percentage of patients, the disease becomes chronic. In these cases, a deregulation in the alternative complement pathway, which can be caused by mutations or autoantibodies, has been proposed as a pathophysiological mechanism. As a result, the alternative complement pathway remains active after resolution of infection. We report a patient with two episodes of acute renal failure, both times diagnosed by renal biopsy of acute endocapillary glomerulonephritis, with slow recovery after two episodes of low-serum complement C3, haematuria and proteinuria.

Renal amyloidosis in leprosy, an infrequent cause of nephrotic syndrome in Europe

Leprosy is a chronic infectious disease caused by Mycobacterium leprae The main clinical manifestations involve the skin and the peripheral nervous system. Several types of nephropathy have been described in leprosy. One frequent form of renal involvement is amyloidosis, especially in patients with lepromatous leprosy. In these patients, end-stage renal disease is an important contributor to morbidity and mortality. Here, we present the case of a patient with nephrotic syndrome caused by secondary amyloidosis, chronic peripheral neuropathy and a history of leprosy. The patient was correctly treated in her youth, which is the best way to avoid renal pathology, but she developed a nephrotic syndrome years later.

Hereditary apolipoprotein AI-associated renal amyloidosis: A diagnostic challenge

Hereditary renal amyloidosis is an autosomal dominant condition with considerable overlap with other amyloidosis types. Differential diagnosis is complicated, but is relevant for prognosis and treatment. We describe a patient with nephrotic syndrome and progressive renal failure, who had a mother with renal amiloidosis. Renal biopsy revealed amyloid deposits in glomerular space, with absence of light chains and protein AA. We suspected amyloidosis with fibrinogen A alpha chain deposits, which is the most frequent cause of hereditary amyloidosis in Europe, with a glomerular preferential affectation. However, the genetic study showed a novel mutation in apolipoprotein AI. On reviewing the biopsy of the patient's mother similar glomerular deposits were found, but there were significant deposits in the renal medulla as well, which is typical in APO AI amyloidosis. The diagnosis was confirmed by immunohistochemistry. Apo AI amyloidosis is characterized by slowly progressive renal disease and end-stage renal disease occurs aproximately 3 to 15 years from initial diagnosis. Renal transplantation offers an acceptable graft survival and in these patients with hepatorenal involvement simultaneous liver and kidney transplantation could be considered.

The active form of vitamin D, calcitriol, induces a complex dual upregulation of endothelin and nitric oxide in cultured endothelial cells

Despite the presence of vitamin D receptor (VDR) in endothelial cells, the effect of vitamin D on endothelial function is unknown. An unbalanced production of vasoactive endothelial factors such as nitric oxide (NO) or endothelin-1 (ET-1) results in endothelial dysfunction, which can alter the normal cardiovascular function. Present experiments were devoted to assess the effect of active vitamin D (calcitriol) on the synthesis of endothelial vasoactive factors. The results were that, in cells, calcitriol increased ET-1 and NO productions, which were measured by ELISA and fluorimetric assay, respectively. Calcitriol also increased endothelin-converting enzyme-1 (ECE-1) and endothelial-nitric oxide synthase (eNOS) activities, their mRNA (qPCR), their protein expressions (Western-blot), and their promoter activities (transfection assays). Calcitriol did not change prepro-ET-1 mRNA. The effect was specific to VDR activation because when VDR was silenced by siRNA, the observed effects disappeared. Mechanisms involved in each upregulation differed. ECE-1 upregulation depended on AP-1 activation, whereas eNOS upregulation depended directly on VDR activation. To evaluate the in vivo consequences of acute calcitriol treatment, normal Wistar rats were treated with a single ip injection of 400 ng/kg calcitriol and euthanized 24 h later. Results confirmed those observed in cells, that production and expression of both factors were increased by calcitriol. Besides, calcitriol-treated rats showed a slight rise in mean blood pressure, which decreased when pretreated with FR-901533, an ECE-1 antagonist. We conclude that calcitriol increases the synthesis of both ET-1 and NO in endothelial cells. However, the ET-1 upregulation seems to be biologically more relevant, as animals acutely treated with calcitriol show slight increases in blood pressure.

Peritoneal Dialysis Can Be an Option for Dominant Polycystic Kidney Disease: an Observational Study

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) has been considered a relative contraindication for peritoneal dialysis (PD), although there are few specific studies available.

METHODS

A multicenter historical prospective matched-cohort study was conducted to describe the outcome of ADPKD patients who have chosen PD. All ADPKD patients starting PD (n = 106) between January 2003 and December 2010 and a control group (2 consecutive patients without ADPKD) were studied. Mortality, PD-technique failure, peritonitis, abdominal wall leaks and cyst infections were compared.

RESULTS

Patients with ADPKD had similar age but less comorbidity at PD inclusion: Charlson comorbidity index (CCI) 4.3 (standard deviation [SD] 1.6) vs 5.3 (SD 2.5) p < 0.001, diabetes mellitus 5.7% vs 29.2%, p < 0.001 and previous cardiovascular events 10.4% vs 27.8%, p < 0.001. No differences were observed in clinical events that required transient transfer to hemodialysis, nor in peritoneal leakage episodes or delivered dialysis dose. The cyst infection rate was low (0.09 episodes per patient-year) and cyst infections were not associated to peritonitis episodes. Overall technique survival was similar in both groups. Permanent transfer to hemodialysis because of surgery or peritoneal leakage was more frequent in ADPKD. More ADPKD patients were included in the transplant waiting list (69.8 vs 58%, p = 0.04) but mean time to transplantation was similar (2.08 [1.69 - 2.47] years). The mortality rate was lower (2.5 vs 7.6 deaths/100 patient-year, p = 0.02) and the median patient survival was longer in ADPKD patients (6.04 [5.39 - 6.69] vs 5.57 [4.95 - 6.18] years, p = 0.024).

CONCLUSION

Peritoneal dialysis is a suitable renal replacement therapy option for ADPKD patients.