Pathogenesis of focal glomerulosclerosis

Patients With Combined Membranous Nephropathy and Focal Segmental Glomerulosclerosis Have Comparable Clinical and Autoantibody Profiles With Primary Membranous Nephropathy: A Retrospective Observational Study

Patients with combined membranous nephropathy (MN) and focal segmental glomerulosclerosis (FSGS) have been reported with different clinical significance. Investigations on the possible mechanisms of the combined glomerular lesions are necessary but scarce. Twenty patients with both MN and FSGS lesions were enrolled in the study. Sixty-five patients with primary MN and 56 patients with primary FSGS were used as disease controls. Clinical data on renal biopsy and during follow-up were collected. Circulating anti-phospholipase A2 receptor (PLA2R) antibody, glomerular PLA2R expression, IgG4 deposition, and soluble urokinase receptor (suPAR) levels were detected. We found that patients with combined lesions presented with older age, less proteinuria, higher albumin, and better renal function on biopsy. These were comparable to the patients with primary MN, but differed from the patients with primary FSGS. Patients with combined lesions showed higher stages of MN, no cellular variant on FSGS classification, and more common (100.0%) tubulointerstitial injury than both primary MN and primary FSGS patients. In the patients with combined lesions, 80.0% had circulating anti-PLA2R antibody and 68.4% had IgG4 predominant deposition in glomeruli, which were comparable to primary MN. The patients with combined lesions had significantly lower urinary suPAR concentrations, than the primary FSGS patients (315.6 ± 151.0 vs 752.1 ± 633.9 pg/μmol; P = 0.002), but similar to the primary MN patients (267.9 ± 147.5 pg/μmol). We conclude that patients with combined MN and FSGS may share the same underlying pathogenesis with primary MN. The FSGS lesion might be secondary to primary MN.

Combination of Immunosuppressive Agents in Treatment of Steroid-Resistant Minimal Change Disease and Primary Focal Segmental Glomerulosclerosis

BACKGROUND

Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are the most prevalent histopathological lesions in idiopathic nephrotic syndrome (INS). The latter is associated with high morbidity and mortality due to symptomatic anasarca, bacterial infections, venous and arterial thromboembolism, and potential progression to end-stage renal disease in the case of FSGS. Traditionally, most patients are treated with corticosteroids, cyclophosphamide (CTX) or calcineurin-inhibitors (C-I). Unfortunately, many patients become steroid or C-I dependent, with the inherent risk of long-term side effects, or are resistant to both. The aim of this paper is to report on our experience with a new protocol of a combination of immunosuppressive agents added sequentially to improve the response of steroid and C-I refractory or resistant-INS and to minimize the long-term side-effects of single-agent treatment.

METHODS

Twenty-one patients with corticosteroid-resistant and C-I refractory INS (6 with MCD and 15 with FSGS) were treated prospectively over 6 and a half years. Our protocol consisted of an initial regimen of C-I followed by the addition of mycophenolate mofetil (MMF) and then by monthly intravenous CTX for 3 consecutive months. Dose reduction of C-I or/and MMF was attempted afterwards at 4-months intervals. Patients who remained refractory to the previously mentioned protocol were treated with an additional course of pulse Solu-Medrol given for 3 days followed by oral corticosteroids tapered over 6 months in addition to a second course of intravenous CTX given for 3 consecutive months.

RESULTS

With the initial regimen, two patients with MCD, remained in complete remission (CR) without any therapy after the course of CTX. Fifteen patients had variable response to C-I and MMF, but they achieved CR after CTX and their initial dosage of C-I and MMF were reduced to nearly one half. The remaining four patients had refractory form of FSGS even after the initial regimen, yet responded with CR to the additional course of steroid/CTX. However, no success with dose-reduction, in C-I and MMF, was achieved in the latter four patients.

CONCLUSION

Our study represents the first clinical trial with prospective and adequate follow-up of combination therapy of immunosuppressive agents in INS. This method is effective and safe for treatment of patients who are refractory to the conventional single-agent therapy.

Accelerated variant of idiopathic pulmonary fibrosis: clinical behavior and gene expression pattern

Background

Idiopathic pulmonary fibrosis (IPF) is characterized by the insidious onset of dyspnea or cough. However, a subset of patients has a short duration of symptoms with rapid progression to end-stage disease. In this study, we evaluated clinical and molecular features of “rapid” and “slow” progressors with IPF.

Methods and Findings

26 patients with <6 months of symptoms before first presentation [rapid progressors] and 88 patients with >24 months of symptoms [slow progressors] were studied. Survival was analyzed by the Kaplan-Meyer method and proportional hazard's model. Lung microarrays and tissue proteins were measured in a subset of patients. No differences were found in age, physiologic impairment and bronchoalveolar lavage (BAL) cellular profile. There were more males (OR = 6.5; CI:1.4-29.5; p = 0.006) and smokers (OR = 3.04; CI:1.1-8.3; p = 0.04) in the rapid progressors group. Survival from the beginning of symptoms was significantly reduced in rapid progressors (HR = 9.0; CI:4.48-18.3; p<0.0001) and there was a tendency for decreased survival from the time of diagnosis (HR = 1.5; CI:0.81-2.87; p = 0.18). We identified 437 differentially expressed genes. Lungs of rapid progressors overexpressed genes involved in morphogenesis, oxidative stress, migration/proliferation, and genes from fibroblasts/smooth muscle cells. Upregulation of two of these genes, adenosine-2B receptor and prominin-1/CD133, was validated by immunohistochemistry and were expressed by alveolar epithelial cells. BAL from rapid progressors showed a >2-fold increase of active matrix metalloproteinase-9, and induced a higher fibroblast migration compared with slow progressors and controls [238±98% versus 123±29% (p<0.05) and 30±17% (p<0.01)].

Conclusions/Significance

A subgroup of IPF patients, predominantly smoking males, display an accelerated clinical course and have a gene expression pattern that is different from those with slower progression and longer survival. These findings highlight the variability in the progression of IPF, and may explain, in part, the difficulty in obtaining significant and reproducible results in studies of therapeutic interventions in patients with IPF.

Low-dose radiation modifies the progression of chronic renal failure

Previous studies have indicated that the application of low dose radiation to an arterial ligation has the potential to subsequently reduce or eliminate restenosis caused by smooth muscle cell proliferation. Sufficient kidney irradiation causes a radiation nephropathy and often leads to renal failure. In order to evaluate the effect of low-dose irradiation on the kidney we hypothesized that this particular therapy modifies renal injury in rats with renal ablation and subsequently slows the rate of the progression. For further clarification of the effect of irradiation at low doses, we determined proliferating cell nuclear antigen (PCNA) and monocyte chemoattractant protein-1 (MCP-1) expression in remnant kidneys after low-dose radiation. Adult Wistar rats (n = 10) were studied during the two weeks after renal ablation. The left kidney was irradiated 24 hours after an operation in anaesthetised animals with 3 Grey in a single dose. Ablated rats without irradiation (n = 9) served as nephrectomized animals group. Rats without surgery and without radiation (n = 10) served as healthy controls. Renal damage was assessed using the following parameters: urine protein excretion rate (UprotV, mg/day), awake systolic blood pressure (SBP, mm Hg), serum creatinine (SCr, micromol/l). The indirect immunofluorescence method was used for the detection of PCNA and MCP-1 expression. Glomerular and tubular immunostaining was scored semiquantitatively. Numerous PCNA positive cells and MCP-1 expression were present in the glomerulus and tubulointerstitium in nephrectomized rat kidneys. Low-dose radiation application was associated with a significant reduction in PCNA and low MCP-1 expression. This study shows that the application of low-dose irradiation has the potential to modify the progression of chronic renal failure in rats.

18. Immune-mediated renal disease

Immune-mediated renal diseases can be classified by the clinical syndromes they produce, by the attendant renal pathology, or by the dominant immune effector mechanism of renal injury. The major clinical syndromes produced by immune-mediated renal injury include the nephrotic syndrome, the nephritic syndrome, rapidly progressive glomerulonephritis, and acute renal failure. The notion of clinical syndromes facilitates diagnosis and treatment, but does not accurately define disease pathogenesis. In this summary, we discuss pathologically defined immune-mediated renal diseases under the clinical syndrome with which they are most frequently associated. There is overlap between the clinical syndromes, but the syndromes provide a useful framework. Relevant information regarding the proposed pathogenesis of disease entities is included under specific disease entities.

Prolonged neuromuscular block due to cholinesterase depletion by plasmapheresis

Plasmapheresis is a well-known therapeutic procedure for several medical conditions in which removal of circulating antibodies or albumin-bound toxins is desired. Circulating plasma cholinesterase enzyme levels are also depleted with plasmapheresis. This action causes patients to be susceptible to prolonged neuromuscular blockade when neuromuscular blocking drugs that are metabolized by this enzyme are used. We describe a case of prolonged neuromuscular blockade following succinylcholine and mivacurium administration in a 24-year-old renal transplant patient undergoing repeated plasmapheresis for recurrence of focal segmental glomerulosclerosis and acute vascular rejection. Serum and plasma cholinesterase levels were less than 20% of normal at the time of the event. The patient had spontaneous recovery after 12 hours of conservative supportive care. She tolerated a similar procedure uneventfully two weeks later when she was not taking plasmapheresis. Anesthesiologists should be aware of plasmapheresis as a mechanism for plasma cholinesterase depletion when using neuromuscular blocking drugs that are metabolized by this enzyme.