Advances in apheresis therapy for glomerular diseases

Double Filtration Plasmapheresis in the Treatment of Antineutrophil Cytoplasmic Autoantibody Associated Vasculitis With Severe Renal Failure: A Preliminary Study of 15 Patients

Our aim was to investigate the clinical efficacy of double filtration plasmapheresis (DFPP) in the treatment of antineutrophil cytoplasmic autoantibody-(ANCA) associated vasculitis (AAV) with severe renal involvement. Fifteen AAV patients who had severe renal failure (median SCr 5.6(IQR 5.2-9.0) mg/dL) and needed initial renal replacement therapy (RRT) were treated with DFPP and immunosuppressive therapy. Two plasma volumes were processed during each DFPP session. The changes of serum ANCA and renal function were investigated. After the DFPP treatment for three to five sessions, serum MPO-ANCA level decreased from 250.0 ± 86.9 RU/mL to 70.5 ± 64.7RU/mL (P = 0.00), with a median reduction rate of 67.6%. Eleven patients (73.3%) no longer needed from RRT 3 months after DFPP treatment, while another four patients remained on dialysis. During the follow up for median 10 (IQR 6-24) months, SCr level decreased to normal in one patient, one patient progressed into ESRD. The 1 year renal survival rate was 62.9%. Five (33.3%) patients were complicated with pulmonary infection. DFPP combined with immunosuppressive therapy could increase the renal recovery rate through rapidly decreasing serum ANCA levels for AAV patients with severe renal failure, but its clinical efficacy and impact on long-term renal survival require further studies.

Successful therapy of C3Nef-positive C3 glomerulopathy with plasma therapy and immunosuppression

BACKGROUND

C3 glomerulopathies (C3G) are characterized by uncontrolled activation of the alternative pathway of complement. In most patients these diseases progress towards end-stage renal disease, and the risk of recurrence after renal transplantation is high. In the majority of patients, only antibodies against the C3 convertase, termed C3Nef, can be found as a potential pathogenic factor. Although a large variety of therapeutic approaches have been used, no generally accepted therapy exists.

METHODS

In four consecutive patients with C3G in whom all known complement factor mutations were excluded and only C3Nef could be identified as a potential cause of disease, a multimodal therapeutic regimen with plasma therapy, corticosteroids and mycophenolate mofetil was used.

RESULTS

The multimodal regimen achieved normalization of renal function in all four patients, with complete remission in two patients and a distinct reduction of proteinuria in the other two patients. The single patient with C3 glomerulonephritis (C3GN) and marked terminal complement complex elevation only showed partial remission; further improvement was achieved following the addition of eculizumab to the therapeutic regimen. Repeatedly measured C3Nef levels did not correlate with disease course or therapeutic response in any of the patients.

CONCLUSIONS

As this multimodal therapeutic approach was effective in all four treated patients with suspected autoimmune etiology of C3G, it offers a treatment option for severely affected patients with this rare disease until more specific regimens are available.

Albumin-associated free fatty acids induce macropinocytosis in podocytes

Podocytes are specialized epithelial cells in the kidney glomerulus that play important structural and functional roles in maintaining the filtration barrier. Nephrotic syndrome results from a breakdown of the kidney filtration barrier and is associated with proteinuria, hyperlipidemia, and edema. Additionally, podocytes undergo changes in morphology and internalize plasma proteins in response to this disorder. Here, we used fluid-phase tracers in murine models and determined that podocytes actively internalize fluid from the plasma and that the rate of internalization is increased when the filtration barrier is disrupted. In cultured podocytes, the presence of free fatty acids (FFAs) associated with serum albumin stimulated macropinocytosis through a pathway that involves FFA receptors, the Gβ/Gγ complex, and RAC1. Moreover, mice with elevated levels of plasma FFAs as the result of a high-fat diet were more susceptible to Adriamycin-induced proteinuria than were animals on standard chow. Together, these results support a model in which podocytes sense the disruption of the filtration barrier via FFAs bound to albumin and respond by enhancing fluid-phase uptake. The response to FFAs may function in the development of nephrotic syndrome by amplifying the effects of proteinuria.

Refractory focal segmental glomerulosclerosis in the adult: complete and sustained remissions of two episodes of nephrotic syndrome after a single dose of rituximab

Rituximab therapy may achieve remission of proteinuria in children or adolescents with refractory focal segmental glomerulosclerosis (FSGS), but its effectiveness in adults is uncertain. We describe the case of a 22-year-old Caucasian woman with refractory FSGS that achieved complete and sustained remission of nephrotic syndrome (NS) with one single 375 mg/m(2) rituximab infusion. At 4 months after complete circulating B-cell depletion, proteinuria declined from 4.5 to 0.27 g/24 h and serum albumin normalised. Rituximab was well tolerated and allowed complete withdrawal of previous immunosuppression with steroids and azathioprine. The patient was in sustained remission up to month 32, when she experienced a relapse. A second infusion of rituximab (375 mg/m(2)) achieved prompt proteinuria reduction with no additional immunosuppressants. At 48 months after the initial treatment, this patient is in complete remission without any immunosuppression. This case suggests that rituximab, even a single dose, may safely promote NS remission in adults with refractory FSGS.

Thrombotic microangiopathy secondary to steroid pulse therapy administered for refractory nephrotic syndrome

A 79-year-old woman with familial hyperlipidemia was treated with low-density lipoprotein apheresis. She was hospitalized due to fatigue and edema, and massive proteinuria was discovered. Renal biopsy revealed no distinct abnormalities, thus suggesting a diagnosis of minimal change nephrotic syndrome. She developed acute kidney injury and hemodialysis was initiated. Two series of steroid pulse therapy were given, but the proteinuria did not decrease. Thereafter, she developed thrombocytopenia and fell into a stupor. Thrombotic microangiopathy (TMA) was the most likely diagnosis. Plasma exchange was initiated, resulting in improvements in platelet counts and in her level of consciousness. Clinicians should therefore be aware that TMA can occur as a result of steroid pulse therapy.

Flowcytometric analysis of lymphocytapheresis in a patient with recurrent FSGS after renal transplant

Frequently, focal segmental glomerulosclerosis (FSGS) recurs after renal transplantation, resulting in poor graft survival. Pathological mechanisms of the recurrence are still unknown, but both B and T cell disorders are suspected based on much evidence. This supports theoretical benefits using plasma exchange (PE) and lymphocytapheresis (LCAP). A renal transplant was performed for a 35-year-old woman, who suffered steroid-resistant FSGS and developed to chronic kidney disease stage 5D at 31 years old. We treated the patient with recurrent FSGS by LACP and examined whether peripheral neutrophils were dynamically changed after the therapy. Further, we performed flowcytometric analysis to examine lymphocyte fractions before and after LCAP. The decrease of helper (CD4 positive) and memory (CD4 and CD45RO positive) T cells was prominent after LCAP. Although B cells were at the nadir because of rituximab treatment, LCAP also decreased peripheral B cells. These suggest that LCAP has the potential to suppress the activities of recurrent FSGS after renal transplant.

An update on the treatment options for focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is not a disease but a lesion initially affecting the podocyte. Various factors may induce 'secondary' FSGS, including defects in molecules that contribute to the podocyte slit diaphragm permselectivity to albumin. They do not represent indications for immunosuppression and require symptomatic treatment only, comprising angiotensin 2 and endothelin antagonists. Primary (idiopathic) FSGS is possibly but not certainly of immunologic origin, owing to an elusive glomerular permeability factor (GPF), explaining relapse on a renal transplant and justifying an immunosuppressive treatment. The best prognostic feature of primary nephrotic FSGS is its response to corticosteroids. Alkylating agents are mostly ineffective in steroid-resistant forms. An association of corticosteroids and cyclosporine A (CsA) remains the mainstay of treatment, with a good tolerability when CsA dosage is low. A definite advantage of tacrolimus on CsA has not yet been established. Sirolimus appears ineffective and potentially harmful. Azathioprine is not indicated. A number of mostly uncontrolled trials indicate that mycophenolate mofetil might find an adjunctive place in the treatment. Plasmapheresis is of no avail outside the special case of relapse in a transplanted kidney. Immunoabsorption of the GPF has not led to practical treatment options. Anecdotal reports on rituximab are as yet too few to determine whether this monoclonal anti-CD20 antibody will find a place in the treatment of primary FSGS.