A case report of crystalline light chain inclusion-associated kidney disease affecting podocytes but without Fanconi syndrome: A clonal analysis of pathological monoclonal light chain.

RATIONALE: Crystalline light chain inclusion-associated kidney disease affects mainly tubular epithelial cells and is often clinically manifested as Fanconi syndrome. However, only very few case reports about the crystalline deposits within the podocytes are available, and the nature of the pathogenic monoclonal light chain implicated in these cases is still unknown. We report a case of crystalline inclusion-associated kidney disease manifested as crystalline podocytopathy in which we identified the complete structure of the pathogenic monoclonal light chain as belonging to the germ-line gene of Vκ1-39. PATIENT CONCERNS: We describe a 65-year-old woman with crystalline light chain inclusion-associated kidney disease showing mild proteinuria and renal insufficiency with monoclonal gammopathy of undetermined significance without Fanconi syndrome. She had crystalline inclusions mainly within podocytes, tubular epithelial cells and histiocytes in the kidney. Light microscopy showed vacuolation of podocytes and tubular epithelial cells, while eosin negative pale needle-like crystals were present within these cells. Electron microscopy showed accumulation of club-like crystals with high electron density in podocytes, proximal tubular epithelial cells and interstitial histiocytes. Clonal analysis revealed that a pathogenic monoclonal light chain was derived from germline gene, Vκ1-39. DIAGNOSES: The diagnosis of crystalline light chain inclusion-associated kidney disease was made. INTERVENTIONS AND OUTCOMES: Bortezomib and dexamethasone were started and her renal function improved to eGFR 36 mL/min/1.73 m after 9 courses of therapy. LESSONS: Patients with light chain crystalline podocytopathy may have a similar pathogenic monoclonal light chain derived from the same germline gene, Vκ1-39, to that of patients with light chain proximal tubulopathy.

Effectiveness of Haemodiafiltration with Heat Sterilized High-Flux Polyphenylene HF Dialyzer in Reducing Free Light Chains in Patients with Myeloma Cast Nephropathy.

INTRODUCTION: In cases of myeloma cast nephropathy in need of haemodialysis (HD), reduction of free light chains using HD with High-Cut-Off filters (HCO-HD), in combination with chemotherapy, may be associated with better renal recovery. The aim of the present study is to evaluate the effectiveness of haemodiafiltration (HDF) in reducing free light chain levels using a less expensive heat sterilized high-flux polyphenylene HF dialyzer (HF-HDF). METHODS: In a single-centre prospective cohort study, 327 dialysis sessions were performed using a 2.2 m2 heat sterilized high-flux polyphenylene HF dialyzer (Phylther HF22SD), a small (1.1m2) or large (2.1 m2) high-cut-off (HCO) dialyzer (HCOS and HCOL) in a cohort of 16 patients presenting with dialysis-dependent acute cast nephropathy and elevated free light chains (10 kappa, 6 lambda). The outcomes of the study were the mean reduction ratio (RR) of kappa and lambda, the proportion of treatments with an RR of at least 0.65, albumin loss and the description of patient outcomes. Statistical analysis was performed using linear and logistic regression through generalized estimating equation analysis so as to take into account repeated observation within subjects and adjust for session duration. RESULTS: There were no significant differences in the estimated marginal mean of kappa RR, which were respectively 0.67, 0.69 and 0.70 with HCOL-HD, HCOS-HDF and HF-HDF (P = 0.950). The estimated marginal mean of the proportions of treatments with a kappa RR ≥0.65 were 68%, 63% and 71% with HCOL-HD, HCOS-HDF and HF-HDF, respectively (P = 0.913). The estimated marginal mean of lambda RR were higher with HCOL-HDF (0.78), compared to HCOL-HD and HF-HDF (0.62, and 0.61 respectively). The estimated marginal mean proportion of treatments with a lambda RR ≥0.65 were higher with HCOL-HDF (81%), compared to 57% in HF-HDF (P = 0.042). The median albumin loss were 7, 21 and 63 g/session with HF-HDF, HCOL-HD and HCOL-HDF respectively (P = 0.044). Among survivors, 9 out of 10 episodes of acute kidney injuries became dialysis-independent following a median time of renal replacement therapy of 40 days (range 7-181). CONCLUSION: Therefore, in patients with acute dialysis-dependent myeloma cast nephropathy, in addition to chemotherapy, HDF with a heat sterilized high-flux polyphenylene HF dialyzer could offer an alternative to HCO dialysis for extracorporeal kappa reduction with lower albumin loss.

Clinical and echocardiographic characteristics for differentiating between transthyretin-related and light-chain cardiac amyloidoses.

Differential diagnosis between transthyretin (TTR) and immunoglobulin light-chain (AL) cardiac amyloidoses is essential due to significantly different prognoses and therapeutic options. Therefore, clinical characteristics of patients with biopsy-proven cardiac amyloidosis were investigated to differentiate TTR from AL amyloidosis. From September 2006 to May 2014, 46 patients were confirmed to have cardiac amyloidosis (TTR, n = 28; AL, n = 18) in our institute. The median age of patients with TTR amyloidosis was 78 years (range 61-90) with 27 (96 %) males, while that of patients with AL amyloidosis was 66 (range 52-76) with 12 (67 %) males. There were no statistically significant differences in echocardiographic findings regarding left ventricular (LV) systolic function or diastolic dysfunction between the two groups. Interestingly, serum brain natriuretic peptide (BNP) levels in patients with AL amyloidosis were significantly higher than those in TTR amyloidosis patients. In contrast, the LV wall was significantly thicker in patients with TTR amyloidosis than in those with AL amyloidosis. Therefore, the ratio of BNP to LV mass index (LVMI) at presentation in AL amyloidosis patients was significantly higher than that in TTR patients (6.7 vs 2.9, p = 0.0006). A BNP-LVMI ratio of less than 3.5 had a diagnostic sensitivity and specificity for TTR amyloidosis of 71 and 83 %, respectively. One-year overall survival was 88.7 % in the patients with TTR amyloidosis and 23.7 % in the patients with AL amyloidosis. Our analysis indicates that the BNP-LVMI ratio, as well as age and sex, may be useful parameters for distinguishing TTR from AL cardiac amyloidosis.

Successful treatment of renal light chain (AL) amyloidosis with bortezomib and dexamethasone (VD).

OBJECTIVE: To assess the efficacy and tolerability of bortezomib with dexamethasone for patients with renal light chain (AL) amyloidosis. METHODS: Twelve newly diagnosed patients with renal AL amyloidosis were treated with a combination of bortezomib (1.3mg/m(2)/d iv, d1, 4, 8, 11) and dexamethasone (20mg/d iv drip, d1-4). RESULTS: Median follow-up time was 22.5 months (range, 2.1-53.6). Ten patients were evaluable. Five out of 10 (50%) patients achieved complete hematologic responses (CHR), and totally 8/10 (80%) achieved hematologic responses (HR). Median time to hematologic response was 1 month. All patients who received HR had no hematologic progression during follow-up period. Five patients (50%) had kidney responses and the other 5 patients (50%) were stable. Median time to kidney response was 3 months. No patients presented renal progression during follow-up. One patient achieved PR after 4 cycles of VD and then received autologous peripheral blood stem cell transplantation. Two out of 10 evaluable patients without hematologic response had died with median overall survival of 8.2 months. Eight of them who had HR were alive with median follow-up time of 28.5 months. Infection (6/12) and fatigue (5/12) were the most frequent side effects. Three patients developed herpes zoster and had to discontinue therapy. CONCLUSIONS: VD produces rapid, deep and durable hematological responses and renal responses in the majority of patients with newly diagnosed renal AL. It is well tolerated. This treatment may be a good option as first-line treatment for renal AL amyloidosis patients.

Use of continuous venovenous hemofiltration for acute renal failure due to multiple myeloma cast nephropathy.

Renal insufficiency is associated with high morbidity and mortality in multiple myeloma. One of the common causes for acute renal failure in multiple myeloma is cast nephropathy. It is important to reduce the levels of light chains to improve renal failure and also the overall outcome. Plasmapheresis has failed to show any significant improvement in renal failure due to cast nephropathy as demonstrated in a recent randomized control trial. Here, we present a case series of three patients who were treated with continuous venovenous hemofiltration as a modality to remove these free light chains. There was improvement in renal failure in these patients with decrease in the levels of free light chains. These patients remained off hemodialysis on follow-up and two of them were able to undergo hematopoietic stem cell transplantation.

Extracorporeal light chain elimination: high cut-off (HCO) hemodialysis parallel to chemotherapy allows for a high proportion of renal recovery in multiple myeloma patients with dialysis-dependent acute kidney injury.

Acute kidney injury (AKI) is frequent in multiple myeloma (MM) patients and strongly affects prognosis, with particularly poor outcomes in patients requiring hemodialysis. Introduction of the novel therapeutic agents to MM therapy has improved myeloma response and renal outcome. This case series reviews the efficacy of combined systemic and extracorporeal therapy to further optimize time to light chain (serum-free light chain (sFLC)) reduction and renal recovery in MM patients with dialysis-dependent AKI (n = 19). High cut-off (HCO) hemodialysis for extracorporeal sFLC removal was initiated in parallel to chemotherapy. Combined therapy resulted in early sFLC response after a median of 13 (range 4-48) days and 6 (3-22) HCO hemodialysis sessions. Time to sFLC response was shorter in patients recovering renal function. Median time to dialysis independence was 15 (4-64) days. By intent-to-treat analysis, sustained renal recovery was achieved in 73.7% (77.8% adjusted for death) of patients. In multivariate analysis, duration of AKI prior to initiation of therapy was an independent predictor of renal functional outcome. Combining HCO hemodialysis for extracorporeal sFLC elimination and effective chemotherapy is a novel treatment strategy allowing for early and sustained sFLC reduction and a high proportion of renal recovery in these patients. Timely diagnosis and onset of therapy is essential for improving renal outcome.

Systemic and microvascular oxidative stress induced by light chain amyloidosis.

Light chain amyloidosis (AL) is a plasma cell dyscrasia associated with production of amyloidogenic immunoglobulin light chains (LC). Despite its often fatal course, the mechanism of injury remains unknown. We tested the hypothesis that AL is associated with oxidative stress by comparing serum protein carbonyl (a marker of protein oxidation and oxidative stress) in AL subjects (n=23, 60 ± 11 years) vs. controls (n=9, 54 ± 2 years); we also measured superoxide production (n=11) and dilator response to sodium nitroprusside (SNP, n=6) in isolated non-AL human adipose arterioles exposed to LC (20 µg/mL) purified from AL subjects for 1 h vs. control. Protein carbonyl was higher in AL patients (0.19 ± 0.04 vs. 0.003 ± 0.003 nmol/mg control, p=0.002). Post-exposure to LC proteins, arteriole superoxide was higher (1.89 ± 0.36 times control, p=0.03) with impaired dilation to SNP (10(-4) M, 54 ± 6 vs. 86 ± 4%, p=0.01, logEC50 -3.7 ± 0.2 vs. -6.7 ± 0.6, p=0.002). AL is associated with systemic oxidative stress and brief acute exposure to AL light chain proteins induces oxidative stress and microvascular dysfunction in human adipose arterioles. This novel mechanism of injury may be important in AL pathophysiology.

A 19-year-old male with generalized seizures, unconsciousness and a deviation of gaze.

Light chain deposition disease (LCDD) is a form of monoclonal immunoglobulin deposition diseases (MIDD) which in contrast to light-chain derived (AL) amyloidosis is characterized by non-congophilic, non-fibrillary monoclonal protein deposits. Systemic organ deposits are common with the kidney being a major target organ. A clonal lymphoplasmocytic proliferation, e.g. plasmacytoma, is present in the majority of cases. Here we report on a 19-year-old male who presented with generalized seizures and an enhancing white matter lesion on MRI scans. A stereotactic brain biopsy revealed a low-grade B cell lymphoma with plasmacellular differentiation as well as lambda light chain deposits without birefringence under polarized microscopy. No systemic lymphoma manifestations or systemic light chain deposits were found, nor was a monoclonal gammopathy detectable in serum and urine. After systemic chemotherapy with three courses high-dose methotrexate the size of the lesion and the condition of the patient have remained stable for 24 months now. This is the first description of cerebral LCDD developing without systemic disease in conjunction with the diagnosis of a cerebral low-grade B cell lymphoma. We present the clinical, laboratory and radiological findings and discuss the pathogenesis of this unusual LCDD manifestation.

Potential protective action of pituitary adenylate cyclase-activating polypeptide (PACAP38) on in vitro and in vivo models of myeloma kidney injury.

The most common type of renal injury in multiple myeloma is chronic tubulointerstitial nephropathy associated with casts in tubule lumens, an entity referred to as "myeloma kidney" that often progresses to end-stage kidney diseases. Myeloma kidney is associated with a significant increase in all-cause mortality, yet no effective intervention, except a limited use of steroid, is available. Here, we report that pituitary adenylate cyclase-activating polypeptide with 38 residues (PACAP38) dramatically prevents injury of cultured renal proximal tubule cells caused by myeloma light chains through suppression of proinflammatory cytokines production, by inhibiting p38 MAPK and translocation of NFkappaB via both PAC(1) and VPAC(1) receptors. The suppressive effects of PACAP was as effective as dexamethasone in all of their cytokine assays and demonstrated both in vitro and in vivo. Furthermore, PACAP38 inhibits myeloma cell growth directly and may also indirectly by suppressing production of the growth factor, IL-6, from bone marrow stromal cells, that is stimulated by adhesion of myeloma cells. These findings render PACAP38 worth evaluation as a promising candidate for an effective and safe renoprotectant in myeloma kidney, and possibly other nephropathy, and also as a new antitumor agent in multiple myeloma.

Effect of immunoglobulin light chains from hemodialysis and continuous ambulatory peritoneal dialysis patients on polymorphonuclear leukocyte functions.

Circulating plasma factors accumulating in the serum of uremic patients have the potential to inhibit essential functions of polymorphonuclear leukocytes (PMNL). As a consequence, these factors can contribute to the increased risk for bacterial infections generally found in uremic patients. Free immunoglobulin light chains that are present in the serum of healthy adults at low levels appear in the serum of uremic patients at significantly higher levels. Therefore, kappa and lambda light chains in their monomeric and dimeric forms were isolated from hemodialysis and continuous ambulatory peritoneal dialysis patients and their potential to inhibit essential PMNL functions in in vitro assays was tested. It was found that all isolates tested were able to inhibit deoxyglucose uptake, a measure for the state of activation of PMNL, as well as chemotaxis. In contrast, free immunoglobulin light chains had no influence on the phagocytotic functions of PMNL. It was concluded that free immunoglobulin light chains are able to act as uremic toxins by interfering with essential PMNL functions and that their serum levels and fate during the treatment of uremic patients should be taken into consideration.

Nephrotoxicity of human Bence Jones protein in rats: proteinuria and enzymuria profile.

The effect of intravenous administration of 80 mg purified human Bence Jones protein twice weekly for 5 weeks was investigated in male Wistar rats (N = 7; 2 months old). A state of immunological tolerance was demonstrated by the absence of a B-cell response (plaque-forming cells and hemagglutination titers) and by the absence of detectable antigen or antibody deposition in glomeruli, as indicated by light and electron microscopy. No rise in blood urea level was detected (33.9 +/- 4.3 vs 32.8 +/- 1.3 mg%). There was an increase in proteinuria (5.3 +/- 0.9 vs 32.8 +/- 4.0 mg/day), mainly due to Bence Jones protein excretion (0 vs 29.2 +/- 5.2 mg/day), with a slight but significant increase in albuminuria (0.2 +/- 0.1 vs 1.0 +/- 0.2 mg/day). There was a significant increase of lysosomal N-acetyl-beta-D-glucosaminidase in the urine (6.1 +/- 1.3 vs 72.7 +/- 18.8 mU/mg in creatinine). Lysosomal accumulation of Bence Jones protein in proximal tubular cells was evidenced by immunoelectronmicroscopy with protein A-gold. These results clearly showed proximal tubular dysfunction induced by chronic Bence Jones protein administration, without interference of autologous immune response as demonstrated by immunological state of tolerance.

Nephrotoxicity of human Bence Jones protein in rats: proteinuria and enzymuria profile

The effect of intravenous administration of 80 mg purified human Bence Jones protein twice weekly for 5 weeks was investigated in male Wistar rats (N = 7; 2 months old). A state of immunological tolerance was demonstrated by the absence of a B-cell response (plaque-forming cells and hemagglutination titers) and by the absence of detectable antigen or antibody deposition in glomeruli, as indicated by light and electron microscopy. No rise in blood urea level was detected (33.9 +/- 4.3 vs 32.8 +/- 1.3 mg per cent ). There was an increase in proteinuria (5.3 +/- 0.9 vs 32.8 +/- 4.0 mg/day), mainly due to Bence Jones protein excretion (0 vs 29.2 +/- 5.2 mg/day), with a slight but significant increase in albuminuria (0.2 +/- 0.1 vs 1.0 +/- 0.2 mg/day). There was a significant increase of lysosomal N-acetyl-beta-D-glucosaminidase in the urine (6.1 +/- 1.3 vs 72.7 +/- 18.8 mU/mg in creatinine). Lysosomal accumulation of Bence Jones protein in proximal tubular cells was evidenced by immunoelectronmicroscopy with protein A-gold. These results clearly showed proximal tubular dysfunction induced by chronic Bence Jones protein administration, without interference of autologous immune response as demonstrated by immunological state of tolerance

Tubular toxicity of filtered proteins.

The mechanisms by which low-molecular-weight proteins filtered at the glomerulus might damage the kidney are reviewed. Despite a strong association between Bence-Jones proteinuria and impairment of renal function, many patients excrete light chains in large amounts and for long periods without evidence of renal abnormality. This critical paradox has still not been resolved despite suggestions, and investigations to explore them, that physicochemical properties of individual proteins might determine toxicity. The data suggest contributions, not mutually exclusive, from toxicity to proximal tubular cells via lysosomal uptake and from tubular obstruction by casts containing light chain and Tamm-Horsfall protein. The mechanisms, if any, of nephrotoxicity of haem proteins are equally uncertain.