The Open Urology & Nephrology Journal




ISSN: 1874-303X ― Volume 12, 2019
RESEARCH ARTICLE

M-Type Phospholipase A2 Receptor Staining in Children with Idiopathic Membranous Nephropathy: PLA2R Staining in Children with IMN



Yosuke Inaguma1, Atsutoshi Shiratori1, Taku Nakagawa1, Kyoko Kanda1, Makiko Yoshida2, Shigeo Hara3, Hiroshi Kaito1, 4, Kandai Nozu4, Kazumoto Iijima4, Norishige Yoshikawa5, Ryojiro Tanaka1, *
1 Department of Nephrology, Hyogo Prefectural Kobe Children’s Hospital, 1-6-7 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
2 Department of Diagnostic Pathology, Hyogo Prefectural Kobe Children’s Hospital, 1-6-7 Minatojima-minamimachi, Chuoku, Kobe, Hyogo 650-0047, Japan
3 Department of Diagnostic Pathology, Kobe City Medical Center General Hospital, 2-1-1 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
4 Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-2 kusunokicho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
5 Clinical Research Center, Wakayama Medical University, 811-1 Kimiidera, Wakayama City, Wakayama 641-8509, Japan

Abstract

Background:

Membranous Nephropathy (MN) is a common cause of nephrotic syndrome in adults that can also occur in children, albeit less frequently. Recently, the M-type phospholipase A2 receptor (PLA2R) was identified as the target antigen in idiopathic membranous nephropathy (IMN), making it a useful marker for diagnosis. However, there are few studies describing the potential role of PLA2R in children with IMN. The aim of this study was to clarify the involvement of PLA2R in childhood IMN.

Methods:

We enrolled 11 patients diagnosed with IMN from January 1998 to March 2017. We performed PLA2R staining in paraffin-embedded renal biopsy sections. The clinical data were collected from the patients’ medical records.

Results:

The median age at biopsy was 6 years (range, 4 to 14 years). A single 6-year-old boy among all pediatric patients with IMN had granular PLA2R staining along his glomerular capillary loops and the prevalence of PLA2R-positivity was 9%. He also showed IgG4 co-dominant staining in terms of IgG subclass. There were no apparent differences in his clinical features such as clinical data at the time of renal biopsy, the time from the treatment initiation to remission, and relapse or renal dysfunction during the follow-up period.

Conclusion:

We suggest that PLA2R staining can be a diagnostic tool for patients with IMN of any age, though pediatric patients with IMN have lower prevalence of PLA2R-positive staining than adult patients.

Keywords: Childhood, Idiopathic membranous nephropathy, IgG subclass, Immunofluorescence staining, Phospholipase A2 receptor, Renal biopsy.


Article Information


Identifiers and Pagination:

Year: 2019
Volume: 12
First Page: 27
Last Page: 32
Publisher Id: TOUNJ-12-27
DOI: 10.2174/1874303X01912010027

Article History:

Received Date: 09/01/2019
Revision Received Date: 13/05/2019
Acceptance Date: 16/05/2019
Electronic publication date: 31/07/2019
Collection year: 2019

Article Metrics:

CrossRef Citations:
0

Total Statistics:

Full-Text HTML Views: 269
Abstract HTML Views: 295
PDF Downloads: 201
ePub Downloads: 177
Total Views/Downloads: 942

Unique Statistics:

Full-Text HTML Views: 163
Abstract HTML Views: 175
PDF Downloads: 136
ePub Downloads: 113
Total Views/Downloads: 587
Geographical View

© 2019 Inaguma et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


* Address correspondence to this author at the Department of Nephrology, Hyogo Prefectural Kobe Children’s Hospital, 1-6-7 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Tel: +81789457300;
Fax: +81783021023; Email: tanaka_kch@hp.pref.hyogo.jp






1. INTRODUCTION

Membranous Nephropathy (MN) is a common cause of immune complex-mediated nephrotic syndrome, which can develop at any age from infants to the elderly [1Ayalon R, Beck LH Jr. Membranous nephropathy: Not just a disease for adults. Pediatr Nephrol 2015; 30(1): 31-9.
[http://dx.doi.org/10.1007/s00467-013-2717-z] [PMID: 24375012]
]. It ispathologically characterized by subepithelial deposits of immune complex [2Larsen CP, Messias NC, Silva FG, Messias E, Walker PD. Determination of primary versus secondary membranous glomerulopathy utilizing phospholipase A2 receptor staining in renal biopsies. Mod Pathol 2013; 26(5): 709-15.
[http://dx.doi.org/10.1038/modpathol.2012.207] [PMID: 23196797]
]. There are a number of etiologies for these deposits, including autoimmune diseases such as Systemic Lupus Erythematosus (SLE), viral hepatitis, malignancy, and drugs such as penicillamine. If such a cause can be identified, it is termed Secondary Membranous Nephropathy (SMN); if none can be identified, it is termed Idiopathic Membranous Nephropathy (IMN). In adults, IMN needs to be considered during diagnosis, but SMN due to SLE, hepatitis B viral infection, and congenital syphilis is more frequent in children [3Beck LH Jr. Childhood membranous nephropathy and dietary antigens. Am J Kidney Dis 2012; 59(2): 174-6.
[http://dx.doi.org/10.1053/j.ajkd.2011.09.009] [PMID: 22014402]
]. To decide on the optimal treatment strategy, it is essential to distinguish IMN from SMN.

A recent study showed that a specific antigen called M-type phospholipase A2 receptor (PLA2R) is found on the podocytes of adult patients with IMN [4Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med 2009; 361(1): 11-21.
[http://dx.doi.org/10.1056/NEJMoa0810457] [PMID: 19571279]
]. In later studies, it was reported that the sensitivity of the presence of PLA2R autoantibodies in the serum was 70-82%, and the sensitivity of PLA2R staining in glomerular tissue was 74% [4Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med 2009; 361(1): 11-21.
[http://dx.doi.org/10.1056/NEJMoa0810457] [PMID: 19571279]
, 5Qin W, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol 2011; 22(6): 1137-43.
[http://dx.doi.org/10.1681/ASN.2010090967] [PMID: 21566055]
], and it has been shown to be a useful marker for diagnosis of IMN. However, several of these reports only investigated adult patients with IMN.

IMN is a rare disease in children; the International Study for Kidney Disease in Children reported that the incidence of MN was 1.5% in children with nephrotic syndrome [6Nephrotic syndrome in children: Prediction of histopathology from clinical and laboratory characteristics at time of diagnosis. A report of the International Study of Kidney Disease in Children. Kidney Int 1978; 13(2): 159-65.
[http://dx.doi.org/10.1038/ki.1978.23] [PMID: 713276]
], and another report showed that 4.5% of the patients who underwent renal biopsy to evaluate proteinuria were diagnosed with MN, with IMN patients constituting 26.4% of all MN patients [7Lee BH, Cho HY, Kang HG, et al. Idiopathic membranous nephropathy in children. Pediatr Nephrol 2006; 21(11): 1707-15.
[http://dx.doi.org/10.1007/s00467-006-0246-8] [PMID: 16951933]
]. There are also few studies on the potential role of PLA2R in childhood IMN [8Cossey LN, Walker PD, Larsen CP. Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy. Pediatr Nephrol 2013; 28(12): 2307-11.
[http://dx.doi.org/10.1007/s00467-013-2574-9] [PMID: 23903693]
-10Kumar V, Ramachandran R, Kumar A, et al. Antibodies to M-type phospholipase A2 receptor in children with idiopathic membranous nephropathy. Nephrology (Carlton) 2015; 20(8): 572-5.
[http://dx.doi.org/10.1111/nep.12478] [PMID: 26194981]
]. Therefore, to clarify the involvement of PLA2R in childhood IMN, we performed immunofluorescent staining using an anti-PLA2R antibody in renal biopsy specimens of Japanese pediatric patients with IMN.

2. MATERIALS AND METHODS

2.1. Patients

The present study enrolled 11 patients whose diagnosis of IMN was pathologically made from kidney biopsies at Hyogo Prefectural Kobe Children’s Hospital and Kobe University Hospital from January 1998 to March 2017. Patients were excluded if they had possible causes of SMN such as autoimmune diseases, hepatitis B or C viral infection and malignancy. The following data were collected from the patients’ medical records: age, gender, serum creatinine (Cr), serum albumin, urine Protein to Creatinine Ratio (uPCR), hematuria at the time of the renal biopsy, the period from onset to the renal biopsy, treatment, and the period from treatment initiation to remission. Glomerular Filtration Rate (GFR) was estimated using serum Cr according to the new Schwartz formula [11Schwartz GJ, Muñoz A, Schneider MF, et al. New equations to estimate GFR in children with CKD. J Am Soc Nephrol 2009; 20(3): 629-37.
[http://dx.doi.org/10.1681/ASN.2008030287] [PMID: 19158356]
]. The treatment strategy was formulated at the discretion of the attending physician. The results of light and electron microscopy, and immunofluorescent staining in all patients were reviewed.

2.2. Pathological Evaluation

All renal biopsy specimens were fixed in formalin and embedded in paraffin. All paraffin sections were stained with hematoxylin and eosin, periodic acid-Schiff, Masson trichrome, and periodic acid-methenamine-silver. The visual findings caused by deposition of immune complexes, such as subepithelial deposits, spike formation, and thickening or bubbling of the glomerular capillary loops, were evaluated using light and electron microscopy. All direct immunofluorescence specimens using frozen sections were stained with fluorescein-tagged rabbit polyclonal antibodies to immunoglobulin G (IgG), IgA, IgM, complement component 1q (C1q), C3, and C4. Additionally, IgG subclass analysis for paraffin-embedded or frozen sections was performed using antibodies against IgG1, IgG2, IgG3, and IgG4 (Invitrogen, Camarillo, CA, USA), followed by fluorescein isothiocyanate-conjugated secondary antibodies (Invitrogen) [12Hara S, Goto S, Kamiura N, et al. Reappraisal of PLA2R1 in membranous nephropathy: Immunostaining method influence and association with IgG4-dominant phenotype. Virchows Arch 2015; 467(1): 87-94.
[http://dx.doi.org/10.1007/s00428-015-1754-3] [PMID: 25820371]
]. The paraffin-embedded and frozen sections were used for IgG subclass analysis of patients 1-7 and patients 8-11, respectively. The paraffin-embedded sections were deparaffinized, and proteinase K was applied for 30 min at room temperature. Each staining intensity was evaluated on a five-grade scale of 0-3+ (0, negative; <1+, spare; 1+, weak; 2+, moderate; 3+, strong). IMN was divided into segmental IMN and global IMN on the basis of the lesion occupied by the IgG deposits along the glomerular capillary on immunofluorescence. Segmental IMN was defined as a lesion occupying less than 50% of the glomerulus, and global IMN comprised a lesion occupying more than 50%. The cases of IMN were staged using electron microscopy images according to the Ehrenreich and Churg classification [13Ehrenreich T, Porush JG, Churg J, et al. Treatment of idiopathic membranous nephropathy. N Engl J Med 1976; 295(14): 741-6.
[http://dx.doi.org/10.1056/NEJM197609302951401] [PMID: 958260]
].

2.3. PLA2R Immunofluorescence

PLA2R was detected in formalin-fixed, paraffin-embedded renal biopsy sections using rabbit polyclonal anti-PLA2R1 antibodies (Sigma-Aldrich, St. Louis, MO, USA) at a dilution of 1:50 followed by highly cross-adsorbed Alexa Fluor 488 goat anti-rabbit IgG (Life Technologies, Carlsbad, CA) at a dilution of 1:100 as previously described [2Larsen CP, Messias NC, Silva FG, Messias E, Walker PD. Determination of primary versus secondary membranous glomerulopathy utilizing phospholipase A2 receptor staining in renal biopsies. Mod Pathol 2013; 26(5): 709-15.
[http://dx.doi.org/10.1038/modpathol.2012.207] [PMID: 23196797]
]. PLA2R staining images were assessed using a conventional immunofluorescence microscope (Olympus, Tokyo, Japan). Each image was run with a positive and negative control. If there was bright granular staining along the glomerular capillary loops for PLA2R, it was considered positive.

2.4. Clinical Outcome

During the follow-up period, remission was defined as resolution of proteinuria and hematuria after treatment. Renal dysfunction was defined as an estimated GFR <90 mL/min/ 1.73m2.

3. RESULTS

The clinical data of the 11 patients who were diagnosed with IMN are shown in Table 1. The median age at the biopsy was 6 years (range, 4 to 14 years), with 7 boys and 4 girls. School urine screening led to the diagnosis of 9 patients, 1 was diagnosed after the appearance of edema, and 1 was diagnosed at pregnancy. Nephrotic syndrome was found at the time of renal biopsy in 3 patients. The average proteinuria at the time of the renal biopsy was 1.9 g/g·Cr, the average serum albumin was 3.2 mg/dL, and serum Cr levels were normal in all patients. As shown in Fig. 1, only patient 8 showed bright granular staining along the glomerular capillary loops for PLA2R, with a positive staining rate of 9%. He was a 6-year-old who was diagnosed incidentally as a result of school urine screening. He had moderate proteinuria (1.9 g/g·Cr), hematuria, as well as mild hypoalbuminemia (3.3 mg/dL) at the time of the renal biopsy.

Table 1
Clinical characteristics of patients diagnosed with idiopathic membranous nephropathy at the time of the renal biopsy.


Fig 1
Phospholipase A2 receptor staining pattern in idiopathic membranous nephropathy. (a) Granular staining for phospholipase A2 receptor (PLA2R) along with glomerular capillary loops in a 6-year-old boy. (b) Granular staining for PLA2R along with glomerular capillary loops in a positive control. (c) No staining for PLA2R in the glomerulus of a negative control.


Table 2
Pathological findings including immunofluorescence and electron microscopy findings. staining intensity on five-grade scale of 0 - 3+; 0, negative; <1+, spare; 1+, weak; 2+, moderate; 3+, strong


The pathological characteristics are shown in Table 2. Immunofluorescence examination showed that all patients had granular deposits of IgG along the glomerular capillary loops, and 8 patients were positive for C3. IgM and IgA staining were positive in 3 and 4 patients, respectively. C1q staining was positive in 3 patients, one of whom showed a “full house” pattern. IgG subclass staining was performed in all patients and was positive in 9 patients. IgG4 dominant or co-dominant staining was observed in 3 of the 9 patients, 1 of whom was PLA2R-positive. IgG3 dominance was observed in 6 patients. Electron microscopy showed that all patients had subepithelial deposits of immune complex, a characteristic finding of MN. According to the Ehrenreich and Churg classification, 6 patients were in stage 1, 3 were in stage 2, and 3 were in an intermediate stage between 1 and 2.

The clinical outcomes during the follow-up period are shown in Table 3. During follow-up, 9 of 11 patients were in remission, and 1 patient with PLA2R-positive staining was in remission within 9 months after the initiation of treatment. The remaining 2 patients did not reach remission because the follow-up period was less than 12 months after the initiation of treatment, but proteinuria and hematuria decreased in both patients. They are currently being treated. None of the 9 patients who had remission relapsed or suffered from renal dysfunction. None of the patients had any indication of SMN clinically and serologically during the follow-up.

4. DISCUSSION

The measurement of serum anti-PLA2R antibody and PLA2R staining of glomerular tissue have been previously reported as useful diagnostic markers of IMN in adults. Phospholipase A2(PLA2), the ligand of PLA2R, plays a key role in inositol-related biological pathway [14Vitale SG, Rossetti P, Corrado F, et al. How to achieve high-quality oocytes? The key role of Myo-Inositol and melatonin. Int J Endocrinol 2016; 20164987436
[http://dx.doi.org/10.1155/2016/4987436] [PMID: 27651794]
]. Physiological significance of PLA2 in MN is not clear, but studies on various diseases has been advanced [15Laganà AS, Rossetti P, Sapia F, et al. Evidence-based and patient-oriented inositol treatment in polycystic ovary syndrome: Changing the perspective of the disease. Int J Endocrinol Metab 2017; 15(1)e43695
[http://dx.doi.org/10.5812/ijem.43695] [PMID: 28835764]
]. Some studies reported that some patients with MN may not have detectable anti-PLA2R antibodies in their serum but have PLA2R deposition in their glomerular capillary loops. Thus, immunofluorescence for PLA2R staining is equivalent or more sensitive than serological measurements for the diagnosis of IMN [16Debiec H, Ronco P. PLA2R autoantibodies and PLA2R glomerular deposits in membranous nephropathy. N Engl J Med 2011; 364(7): 689-90.
[http://dx.doi.org/10.1056/NEJMc1011678] [PMID: 21323563]
, 17Qin HZ, Zhang MC, Le WB, et al. Combined assessment of phospholipase A2 receptor autoantibodies and glomerular deposits in membranous nephropathy. J Am Soc Nephrol 2016; 27(10): 3195-203.
[http://dx.doi.org/10.1681/ASN.2015080953] [PMID: 26989120]
]. In children, the incidence of IMN is lower than in adults, and there are few reports on the involvement of PLA2R in childhood IMN. Therefore, we performed immunofluorescent staining using anti-PLA2R antibodies in renal biopsy specimens from pediatric patients with IMN, and investigated the involvement of PLA2R in childhood IMN.

The most remarkable finding in our study was that even younger patient with IMN showed positive staining of PLA2R. Some previous reports indicated that all PLA2R-positive pediatric patients with IMN were older than 10 years, suggesting that PLA2R might a play role in adolescent and preteen IMN patients [8Cossey LN, Walker PD, Larsen CP. Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy. Pediatr Nephrol 2013; 28(12): 2307-11.
[http://dx.doi.org/10.1007/s00467-013-2574-9] [PMID: 23903693]
, 9Kanda S, Horita S, Yanagihara T, Shimizu A, Hattori M. M-type phospholipase A2 receptor (PLA2R) glomerular staining in pediatric idiopathic membranous nephropathy. Pediatr Nephrol 2017; 32(4): 713-7.
[http://dx.doi.org/10.1007/s00467-016-3552-9] [PMID: 27921164]
]. Combined with the single previous report [10Kumar V, Ramachandran R, Kumar A, et al. Antibodies to M-type phospholipase A2 receptor in children with idiopathic membranous nephropathy. Nephrology (Carlton) 2015; 20(8): 572-5.
[http://dx.doi.org/10.1111/nep.12478] [PMID: 26194981]
], IMN patients at any age could be PLA2R-positive in kidney specimens. Further accumulation of data is required to confirm our findings.

In our study, one patient showed bright granular staining along the glomerular capillary loops for PLA2R and the prevalence of PLA2R-positivity was 9%. The prevalence of PLA2R staining along glomerular capillary loops in adult patients with IMN has been reported to range between 53% and 84% [5Qin W, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol 2011; 22(6): 1137-43.
[http://dx.doi.org/10.1681/ASN.2010090967] [PMID: 21566055]
, 18Hayashi N, Akiyama S, Okuyama H, et al. Clinicopathological characteristics of M-type phospholipase A2 receptor (PLA2R)-related membranous nephropathy in Japanese. Clin Exp Nephrol 2015; 19(5): 797-803.
[http://dx.doi.org/10.1007/s10157-014-1064-0] [PMID: 25492250]
-20Hihara K, Iyoda M, Tachibana S, et al. Anti-phospholipase A2 receptor (PLA2R) antibody and glomerular PLA2R expression in Japanese patients with membranous nephropathy. PLoS One 2016; 11(6)e0158154
[http://dx.doi.org/10.1371/journal.pone.0158154] [PMID: 27355365]
]. In children, Cossey et al. reported that PLA2R-positivity was found in 45% of IMN patients [8Cossey LN, Walker PD, Larsen CP. Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy. Pediatr Nephrol 2013; 28(12): 2307-11.
[http://dx.doi.org/10.1007/s00467-013-2574-9] [PMID: 23903693]
]. On the other hand, Kanda et al. reported that it was only observed in 6% of pediatric patients with IMN in Japan [9Kanda S, Horita S, Yanagihara T, Shimizu A, Hattori M. M-type phospholipase A2 receptor (PLA2R) glomerular staining in pediatric idiopathic membranous nephropathy. Pediatr Nephrol 2017; 32(4): 713-7.
[http://dx.doi.org/10.1007/s00467-016-3552-9] [PMID: 27921164]
], which was almost equivalent to our findings. There may be several explanations for this discrepancy; first, the differences in the prevalence of PLA2R staining may be due to the studies’ small sample sizes. Second, it may also be explained by differences in the racial makeup of the study cohorts in the USA and Japan. In adult IMN patients, the prevalence of anti-PLA2R antibodies was 70-82% in American patients [4Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med 2009; 361(1): 11-21.
[http://dx.doi.org/10.1056/NEJMoa0810457] [PMID: 19571279]
, 5Qin W, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol 2011; 22(6): 1137-43.
[http://dx.doi.org/10.1681/ASN.2010090967] [PMID: 21566055]
, 19Hofstra JM, Beck LH Jr, Beck DM, Wetzels JF, Salant DJ. Anti-phospholipase A2 receptor antibodies correlate with clinical status in idiopathic membranous nephropathy. Clin J Am Soc Nephrol 2011; 6(6): 1286-91.
[http://dx.doi.org/10.2215/CJN.07210810] [PMID: 21474589]
], whereas that in Japanese was only 50-55% [18Hayashi N, Akiyama S, Okuyama H, et al. Clinicopathological characteristics of M-type phospholipase A2 receptor (PLA2R)-related membranous nephropathy in Japanese. Clin Exp Nephrol 2015; 19(5): 797-803.
[http://dx.doi.org/10.1007/s10157-014-1064-0] [PMID: 25492250]
, 20Hihara K, Iyoda M, Tachibana S, et al. Anti-phospholipase A2 receptor (PLA2R) antibody and glomerular PLA2R expression in Japanese patients with membranous nephropathy. PLoS One 2016; 11(6)e0158154
[http://dx.doi.org/10.1371/journal.pone.0158154] [PMID: 27355365]
, 21Akiyama S, Akiyama M, Imai E, Ozaki T, Matsuo S, Maruyama S. Prevalence of anti-phospholipase A2 receptor antibodies in Japanese patients with membranous nephropathy. Clin Exp Nephrol 2015; 19(4): 653-60.
[http://dx.doi.org/10.1007/s10157-014-1054-2] [PMID: 25412738]
]. A clear mechanism linking PLA2R-positivity with race is unknown. Third, differences in the prevalence of PLA2R-positivity may be related to age; the median age of the study patients reported by Cossey et al. was 14 years [8Cossey LN, Walker PD, Larsen CP. Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy. Pediatr Nephrol 2013; 28(12): 2307-11.
[http://dx.doi.org/10.1007/s00467-013-2574-9] [PMID: 23903693]
], whereas in our study it was 6 years. Finally, the different prevalence may also be related to disease activity and the degree of proteinuria. Beck and Salant speculated that the absence of anti-PLA2R antibodies in the serum indicated an absence of immunologic disease activity at the time [22Beck LH Jr, Salant DJ. Membranous nephropathy: Recent travels and new roads ahead. Kidney Int 2010; 77(9): 765-70.
[http://dx.doi.org/10.1038/ki.2010.34] [PMID: 20182413]
]. In addition, Qin et al. reported that in patients who had achieved remission, PLA2R antigen deposits showed a trend towards decrease or remaining unchanged, whereas in patients not in remission, they tended to increase or remained stable [17Qin HZ, Zhang MC, Le WB, et al. Combined assessment of phospholipase A2 receptor autoantibodies and glomerular deposits in membranous nephropathy. J Am Soc Nephrol 2016; 27(10): 3195-203.
[http://dx.doi.org/10.1681/ASN.2015080953] [PMID: 26989120]
].

We performed IgG subclass analysis with immunofluorescence staining for all renal biopsy specimens in our study. The previous studies had suggested that IgG4 dominant staining was associated with IMN, whereas SMN was dominantly stained with IgG1, IgG2 and IgG3 [18Hayashi N, Akiyama S, Okuyama H, et al. Clinicopathological characteristics of M-type phospholipase A2 receptor (PLA2R)-related membranous nephropathy in Japanese. Clin Exp Nephrol 2015; 19(5): 797-803.
[http://dx.doi.org/10.1007/s10157-014-1064-0] [PMID: 25492250]
, 23Segawa Y, Hisano S, Matsushita M, et al. IgG subclasses and complement pathway in segmental and global membranous nephropathy. Pediatr Nephrol 2010; 25(6): 1091-9.
[http://dx.doi.org/10.1007/s00467-009-1439-8] [PMID: 20151159]
]. On the other hand, IMN with segmentally positive staining of IgG, which is called segmental IMN, showed different pattern of IgG subclass staining; positive staining of IgG1 and IgG3 [23Segawa Y, Hisano S, Matsushita M, et al. IgG subclasses and complement pathway in segmental and global membranous nephropathy. Pediatr Nephrol 2010; 25(6): 1091-9.
[http://dx.doi.org/10.1007/s00467-009-1439-8] [PMID: 20151159]
]. These would result from the difference of stage in IMN, which means that segmental IMN would be thought as either an early stage or incomplete form of global IMN [23Segawa Y, Hisano S, Matsushita M, et al. IgG subclasses and complement pathway in segmental and global membranous nephropathy. Pediatr Nephrol 2010; 25(6): 1091-9.
[http://dx.doi.org/10.1007/s00467-009-1439-8] [PMID: 20151159]
]. In our study, 3 patients with global IMN had IgG4 dominant staining and 2 patients with segmental IMN showed IgG3 dominant staining, suggesting that this finding is consistent with a similar trend reported by Segawa et al. [23Segawa Y, Hisano S, Matsushita M, et al. IgG subclasses and complement pathway in segmental and global membranous nephropathy. Pediatr Nephrol 2010; 25(6): 1091-9.
[http://dx.doi.org/10.1007/s00467-009-1439-8] [PMID: 20151159]
]. In terms of the relation between PLA2R and IgG subclass analysis, the previous report mentioned that serum anti-PLA2R antibody in human consists of IgG4, and the PLA2R antigen could be co-localized with IgG4 in glomerular immune deposits of IMN [4Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med 2009; 361(1): 11-21.
[http://dx.doi.org/10.1056/NEJMoa0810457] [PMID: 19571279]
, 24Hofstra JM, Debiec H, Short CD, et al. Antiphospholipase A2 receptor antibody titer and subclass in idiopathic membranous nephropathy. J Am Soc Nephrol 2012; 23(10): 1735-43.
[http://dx.doi.org/10.1681/ASN.2012030242] [PMID: 22956816]
]. IgG4 dominant deposits in glomeruli were mainly found in PLA2R related patients [19Hofstra JM, Beck LH Jr, Beck DM, Wetzels JF, Salant DJ. Anti-phospholipase A2 receptor antibodies correlate with clinical status in idiopathic membranous nephropathy. Clin J Am Soc Nephrol 2011; 6(6): 1286-91.
[http://dx.doi.org/10.2215/CJN.07210810] [PMID: 21474589]
]. Consistent with these findings, 1 patient who was PLA2R-positive showed IgG4 co-dominant staining in IgG subclass. IgG subclass analysis, as well as PLA2R staining, would achieve a certain result to confirm IMN in children.

Table 3
Clinical outcome during follow-up.


Several limitations exist with respect to this study. First, the sample size of our study was small. Second, we were unable to mention about anti-PLA2R antibodies in the serum which we did not measure. Although PLA2R staining of glomerular tissue is equivalent or more sensitive than serological measurements for the diagnosis of IMN in adults, if we had evaluated serum anti-PLA2R antibodies, it might have been revealed that the serum findings correlate with the renal biopsy findings.

CONCLUSION

In conclusion, this study showed that the IMN patient who was positive for PLA2R was a young boy. Although the prevalence of PLA2R-positivity in pediatric patients with IMN was lower than adult patients, PLA2R staining can be a diagnostic tool for patients with IMN of any age.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

This study was approved by Ethical Committee of Hyogo Prefectural Kobe Children’s Hospital No: 26-20.

HUMAN AND ANIMAL RIGHTS

All procedures performed in this studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

CONSENT FOR PUBLICATION

Informed consent was obtained from all the participants.

AVAILABILITY OF DATA AND MATERIALS

Not applicable.

FUNDING

K. Iijima reports grants from Novartis Pharma K.K., grants from Japan Blood Product Organization, grants from AbbVie LLC, grants from JCR Pharmaceuticals Co., Ltd., grants from Daiichi Sankyo, Co., Ltd., grants from Teijin Pharma Ltd., grants from CSL Behring, grants from Novo Nordisk Pharma Ltd., grants from Air Water Medical Inc., grants from Astellas Pharma Inc., grants from Takeda Pharmaceutical Co., Ltd., grants from Taisho Toyama Pharmaceutical Co., Ltd., grants from Eisai Co. Ltd., grants from Biofermin Pharmaceutical Co., Ltd., from Zenyaku Kogyo Co., personal fees from Zenyaku Kogyo Co., Ltd., personal fees from Novartis Pharma K.K., personal fees from Chugai Pharmaceutical Co., Ltd., personal fees from Astellas Pharma Inc., personal fees from Springer Japan KK, personal fees from Meiji Seika Pharma Co., Ltd., personal fees from Asahi kasei Pharma Corporation, personal fees from Medical Review Co.,Ltd, personal fees from Nippon Boehringer Ingelheim Co ., Ltd., personal fees from Baxter Limited, personal fees from Ono Pharmaceutical Co., Ltd., personal fees from Sanwa Kagaku Kenkyusho Co.,Ltd., personal fees from Sanofi K.K., personal fees from Alexion Pharma LLC., personal fees from Kyowa Hakko Kirin Co., Ltd., outside the submitted work.

CONFLICT OF INTEREST

Y. Inaguma, A. Shiratori, T. Nakagawa, K. Kanda, M. Yoshida, S. Hara, H. Kaito, K. Nozu, N. Yoshikawa and R. Tanaka declare that there is no conflict of interest in this study.

ACKNOWLEDGEMENTS

Declared none.

REFERENCES

[1] Ayalon R, Beck LH Jr. Membranous nephropathy: Not just a disease for adults. Pediatr Nephrol 2015; 30(1): 31-9.
[http://dx.doi.org/10.1007/s00467-013-2717-z] [PMID: 24375012]
[2] Larsen CP, Messias NC, Silva FG, Messias E, Walker PD. Determination of primary versus secondary membranous glomerulopathy utilizing phospholipase A2 receptor staining in renal biopsies. Mod Pathol 2013; 26(5): 709-15.
[http://dx.doi.org/10.1038/modpathol.2012.207] [PMID: 23196797]
[3] Beck LH Jr. Childhood membranous nephropathy and dietary antigens. Am J Kidney Dis 2012; 59(2): 174-6.
[http://dx.doi.org/10.1053/j.ajkd.2011.09.009] [PMID: 22014402]
[4] Beck LH Jr, Bonegio RG, Lambeau G, et al. M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy. N Engl J Med 2009; 361(1): 11-21.
[http://dx.doi.org/10.1056/NEJMoa0810457] [PMID: 19571279]
[5] Qin W, Beck LH Jr, Zeng C, et al. Anti-phospholipase A2 receptor antibody in membranous nephropathy. J Am Soc Nephrol 2011; 22(6): 1137-43.
[http://dx.doi.org/10.1681/ASN.2010090967] [PMID: 21566055]
[6] Nephrotic syndrome in children: Prediction of histopathology from clinical and laboratory characteristics at time of diagnosis. A report of the International Study of Kidney Disease in Children. Kidney Int 1978; 13(2): 159-65.
[http://dx.doi.org/10.1038/ki.1978.23] [PMID: 713276]
[7] Lee BH, Cho HY, Kang HG, et al. Idiopathic membranous nephropathy in children. Pediatr Nephrol 2006; 21(11): 1707-15.
[http://dx.doi.org/10.1007/s00467-006-0246-8] [PMID: 16951933]
[8] Cossey LN, Walker PD, Larsen CP. Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy. Pediatr Nephrol 2013; 28(12): 2307-11.
[http://dx.doi.org/10.1007/s00467-013-2574-9] [PMID: 23903693]
[9] Kanda S, Horita S, Yanagihara T, Shimizu A, Hattori M. M-type phospholipase A2 receptor (PLA2R) glomerular staining in pediatric idiopathic membranous nephropathy. Pediatr Nephrol 2017; 32(4): 713-7.
[http://dx.doi.org/10.1007/s00467-016-3552-9] [PMID: 27921164]
[10] Kumar V, Ramachandran R, Kumar A, et al. Antibodies to M-type phospholipase A2 receptor in children with idiopathic membranous nephropathy. Nephrology (Carlton) 2015; 20(8): 572-5.
[http://dx.doi.org/10.1111/nep.12478] [PMID: 26194981]
[11] Schwartz GJ, Muñoz A, Schneider MF, et al. New equations to estimate GFR in children with CKD. J Am Soc Nephrol 2009; 20(3): 629-37.
[http://dx.doi.org/10.1681/ASN.2008030287] [PMID: 19158356]
[12] Hara S, Goto S, Kamiura N, et al. Reappraisal of PLA2R1 in membranous nephropathy: Immunostaining method influence and association with IgG4-dominant phenotype. Virchows Arch 2015; 467(1): 87-94.
[http://dx.doi.org/10.1007/s00428-015-1754-3] [PMID: 25820371]
[13] Ehrenreich T, Porush JG, Churg J, et al. Treatment of idiopathic membranous nephropathy. N Engl J Med 1976; 295(14): 741-6.
[http://dx.doi.org/10.1056/NEJM197609302951401] [PMID: 958260]
[14] Vitale SG, Rossetti P, Corrado F, et al. How to achieve high-quality oocytes? The key role of Myo-Inositol and melatonin. Int J Endocrinol 2016; 20164987436
[http://dx.doi.org/10.1155/2016/4987436] [PMID: 27651794]
[15] Laganà AS, Rossetti P, Sapia F, et al. Evidence-based and patient-oriented inositol treatment in polycystic ovary syndrome: Changing the perspective of the disease. Int J Endocrinol Metab 2017; 15(1)e43695
[http://dx.doi.org/10.5812/ijem.43695] [PMID: 28835764]
[16] Debiec H, Ronco P. PLA2R autoantibodies and PLA2R glomerular deposits in membranous nephropathy. N Engl J Med 2011; 364(7): 689-90.
[http://dx.doi.org/10.1056/NEJMc1011678] [PMID: 21323563]
[17] Qin HZ, Zhang MC, Le WB, et al. Combined assessment of phospholipase A2 receptor autoantibodies and glomerular deposits in membranous nephropathy. J Am Soc Nephrol 2016; 27(10): 3195-203.
[http://dx.doi.org/10.1681/ASN.2015080953] [PMID: 26989120]
[18] Hayashi N, Akiyama S, Okuyama H, et al. Clinicopathological characteristics of M-type phospholipase A2 receptor (PLA2R)-related membranous nephropathy in Japanese. Clin Exp Nephrol 2015; 19(5): 797-803.
[http://dx.doi.org/10.1007/s10157-014-1064-0] [PMID: 25492250]
[19] Hofstra JM, Beck LH Jr, Beck DM, Wetzels JF, Salant DJ. Anti-phospholipase A2 receptor antibodies correlate with clinical status in idiopathic membranous nephropathy. Clin J Am Soc Nephrol 2011; 6(6): 1286-91.
[http://dx.doi.org/10.2215/CJN.07210810] [PMID: 21474589]
[20] Hihara K, Iyoda M, Tachibana S, et al. Anti-phospholipase A2 receptor (PLA2R) antibody and glomerular PLA2R expression in Japanese patients with membranous nephropathy. PLoS One 2016; 11(6)e0158154
[http://dx.doi.org/10.1371/journal.pone.0158154] [PMID: 27355365]
[21] Akiyama S, Akiyama M, Imai E, Ozaki T, Matsuo S, Maruyama S. Prevalence of anti-phospholipase A2 receptor antibodies in Japanese patients with membranous nephropathy. Clin Exp Nephrol 2015; 19(4): 653-60.
[http://dx.doi.org/10.1007/s10157-014-1054-2] [PMID: 25412738]
[22] Beck LH Jr, Salant DJ. Membranous nephropathy: Recent travels and new roads ahead. Kidney Int 2010; 77(9): 765-70.
[http://dx.doi.org/10.1038/ki.2010.34] [PMID: 20182413]
[23] Segawa Y, Hisano S, Matsushita M, et al. IgG subclasses and complement pathway in segmental and global membranous nephropathy. Pediatr Nephrol 2010; 25(6): 1091-9.
[http://dx.doi.org/10.1007/s00467-009-1439-8] [PMID: 20151159]
[24] Hofstra JM, Debiec H, Short CD, et al. Antiphospholipase A2 receptor antibody titer and subclass in idiopathic membranous nephropathy. J Am Soc Nephrol 2012; 23(10): 1735-43.
[http://dx.doi.org/10.1681/ASN.2012030242] [PMID: 22956816]
Society Affiliation


Endorsements



"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."


Daniel Pesut
(Indiana University School of Nursing, USA)

"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."


Jacques Descotes
(Centre Antipoison-Centre de Pharmacovigilance, France)

"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."


Patrice Talaga
(UCB S.A., Belgium)

"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."


Jeffrey M. Weinberg
(St. Luke's-Roosevelt Hospital Center, USA)

"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."


Debomoy K. Lahiri
(Indiana University School of Medicine, USA)

"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."


Robert Looney
(Naval Postgraduate School, USA)

"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."


Richard Reithinger
(Westat, USA)

"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."


J. Ferwerda
(University of Oxford, UK)

"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."


Sean L. Kitson
(Almac Sciences, Northern Ireland)

"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."


Hubert Wolterbeek
(Delft University of Technology, The Netherlands)

"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."


Alessandro Laviano
(Sapienza - University of Rome, Italy)

"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."


Philippe Hernigou
(Paris University, France)

"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."


Fidel Toldrá
(Instituto de Agroquimica y Tecnologia de Alimentos, Spain)

"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."


M. Bendandi
(University Clinic of Navarre, Spain)

"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."


Peter Chiba
(University of Vienna, Austria)

"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."


Jaime Sampaio
(University of Trás-os-Montes e Alto Douro, Portugal)

"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."


Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."


Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."


Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."


Jih Ru Hwu
(National Central University, Taiwan)


Browse Contents




Webmaster Contact: info@benthamopen.net
Copyright © 2019 Bentham Open