2018/2019
Rodrigo Manuel Brás Batata
The role of Anti-phospholipase A2 Receptor Autoantibody as
a biomarker of Idiopathic Membranous Nephropathy /
O papel do autoanticorpo anti-receptor fosfopilase A2 como
biomarcador da Nefropatia Membranosa Idiopática
Mestrado Integrado em Medicina
Área: Nefrologia Tipologia: Monografia
Trabalho efetuado sob a Orientação de: Professor Doutor Luís Alexandre de Castilho Silva Coentrão
Trabalho organizado de acordo com as normas da revista: Portuguese Journal of Nephrology and Hypertension
Rodrigo Manuel Brás Batata
The role of Anti-phospholipase A2 Receptor Autoantibody as a
biomarker of Idiopathic Membranous Nephropathy / O papel do
autoanticorpo anti-receptor fosfopilase A2 como biomarcador da
Nefropatia Membranosa Idiopática.
Agradecimentos
Em primeiro lugar quero agradecer ao meu Orientador, Professor Doutor Luís Coentrão, pela sua disponibilidade, pelas suas elevadas qualidades humanas e pela valorização do conhecimento rigoroso e científico com que ao longo da realização deste trabalho me brindou.
À minha família que foi o meu grande pilar neste meu percurso académico, em especial à minha Mãe e ao meu Pai.
Uma palavra de apreço ao meu amigo Pedro Bem-Haja pela forma altruísta com que sempre me acompanhou.
À Diana pelo apoio incondicional.
Ao Filipe Pimentel pela amizade verdadeira.
Index
Abstract ... 6 Resumo ... 7 Introduction ... 8 Methods ... 10 Results ... 12 Discussion ... 14 Conclusion ... 17 References ... 18 Appendix ... 23 Appendix I – Table I ... 23Appendix II - Portuguese Journal of Nephrology and Hypertension: Instructions to Authors ... 32
Abstract
Background: Membranous nephropathy (MN) is an important cause of nephrotic syndrome in adults. The M-type phospholipase A2 receptor (PLA2R) present in the podocyte, has been identified as the major antigenic target of the immune response underlying idiopathic membranous nephropathy (MNI). In the last years, anti-PLA2R antibodies has been pointed out by several authors, as a promising biomarker in the differential diagnosis of MNI and secondary membranous nephropathy (SMN), in the assessment of disease activity, prognosis, therapeutic monitoring and risk evaluation of renal transplant recurrence.
Objective: To review clinical studies exploring the relationship between this biomarker and IMN.
Methods: This systematic review was conducted according to PRISMA guidelines. Two databases were searched for articles published between January 2010 and October 2018. Of the 83 articles found in databases, forty-two studies were identified that met the inclusion criteria.
Results: The anti-PLA2R antibody is a sensitive and highly specific marker for INM. There is a correlation between antibody titers and disease activity. Low levels of this biomarker or seronegativity correlate with higher remission rates. The relative reduction of antibodies seems to correlate with response to therapy rather than absolute reduction. The value of this antibody in the prediction of post-transplant recurrence is uncertain. Conclusion: The anti-PLA2R antibody is the main biomarker of INM and should be included in a rational way in the management of this pathology.
Resumo
Introdução: A nefropatia membranosa (NM) é uma causa importante de síndrome nefrótica nos adultos. O receptor da fosfolipase A2 do tipo M (PLA2R) presente no podócito tem sido apontado como o principal alvo antigénico da resposta imunológica subjacente à nefropatia membranosa idiopática (NMI). O doseamento dos anticorpos anti-PLA2R tem sido apontado, nos últimos anos, por diversos autores como um biomarcador promissor no diagnóstico diferencial da NMI com a nefropatia membranosa secundária (NMS), na avaliação da atividade da doença, no prognóstico, na monitorização terapêutica e na avaliação do risco de recorrência pós-transplantação renal.
Objetivo: Realizar uma revisão dos estudos clínicos que explorem a relação entre este biomarcador e a MNI.
Métodos: Esta revisão sistemática foi conduzida de acordo com as diretrizes do PRISMA. Foram pesquisados em duas bases de dados artigos publicados entre janeiro de 2010 e outubro de 2018. Dos 83 artigos encontrados nas bases de dados, foram identificados 42 estudos que preencheram os critérios de inclusão.
Resultados: O anticorpo anti-PLA2R é um marcador sensível e altamente específico para a NMI. Existe uma correlação dos títulos de anticorpos e a atividade da doença. Níveis baixos ou nulos deste biomarcardor correlacionam-se com maiores taxas de remissão. A redução relativa de anticorpos parece correlacionar-se com a resposta à terapêutica ao invés da redução absoluta. O valor deste anticorpo na previsão da recorrência pós-transplante é incerto.
Conclusão: O anticorpo anti-PLA2R é o principal biomarcador da NMI, devendo ser incluído de forma racional na gestão desta patologia.
Introduction
Membranous nephropathy (MN) is the denomination of a specific glomerular disease characterized by the deposition of immune complexes at the glomerular basement membrane (GBM), inducing its thickening.1 This immunological process alter the
permeability of the glomerular capillary walls, provoking proteinuria and nephrotic syndrome (NS) which is characterized by the following criteria: proteinuria (> 3-3.5 g/24 hour) or spot urine protein: creatinine ratio of >300-350 mg/mmol, serum albumin <25 g/l, clinical evidence of peripheral edema and hyperlipidaemia (total cholesterol often >10 mmol/l).2,3 MN is an important cause of NS, accounting nearly 20% of all cases.2
One third of MN patients will present spontaneous remission and another third develop end-stage renal failure in ten years.4
Approximately 20% of all events of MN have an underlying condition (malignancies, drugs or toxics, rheumatological diseases and infections) which is responsible by secondary MN (SMN).5 However SMN will not be discussed further in this paper.
Idiopathic membranous nephropathy (IMN) is the term used for the remaining conditions that do not have an identified cause. The pathological mechanisms of the IMN are not yet clear.6
In 1959, W. Heymann developed an experimental model in rats that allowed a better understanding of the underlying mechanism of IMN. Based on Heymann's studies, a podocyte antigen, megalin, was described as the target for the ciculating antibodies resulting in the formation of immune complexes.Despite the importance of these new understandings,the mechanisms described above are not transposable to humans. 7–11
Years later P. Ronco observed that mothers with (Neutral Endopeptidase) NEP deficiency developed IgG1 and IgG4 antibodies capable of crossing the placenta and binding to the NEP expressed by the fetus, inducing neonatal MN. This observation was important to note that podocytes are targets for circulating antibodies, leading to complement activation and subsequent deposition of glomerular immune complexes.12,13
The M-type phospholipase A2 receptor 1 (PLA2R1) has recently been identified as being the main target antigen, and it is possible to find a circulating antibodies against PLA2R1 in approximately 70% of IMN patients.14
According to the latest studies, there is a strong correlation between levels of circulating Anti-PLA2R1 antibodies and disease activity, measured by proteinuria level. However,
it is necessary to be careful in the interpretation of discordant levels of antibodies and proteinuria. Low or absent antibody levels indicate remission or low disease activity, but positive values of proteinuria may be an indirect sign of glomerular structural changes or tubular damage.15 Anti-PLA2R1 antibodies can also be used to predict the course of the
disease and to evaluate the response to treatment.16,17 The risk assessment of recurrence
of IMN after kidney transplantation can also be performed using these antibodies and they are very useful to optimize the immunosuppressive therapy.18–20
The purpose of this paper is to understand the role of anti-PLAR1 antibodies as biomarkers of IMN, analyzing their usefulness in the evaluation of disease activity, therapeutic monitoring, differential diagnosis with secondary forms and evaluation of the risk of recurrence, based on a review of recent data from clinical studies related to the topic at hand.
Methods
This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA; see Figure 1) guidelines. The articles search for the present review was carried out between September and October of 2018. Two different electronic databases were used to conduct literature searches, PUBMED and SCOPUS. The authors of the study agreed on the search strategy and defined the set of inclusion and exclusion criteria for automatic and manual depuration processes (see Figure 1). The search criteria were later transformed into queries according to the code of each database; SCOPUS ((TITLE(phospholipase A2) AND TITLE(Membranous Nephropathy)) AND ( TO ( PUBYEAR,2018) OR LIMIT-TO ( PUBYEAR,2017) OR LIMIT-LIMIT-TO ( PUBYEAR,2016) OR LIMIT-LIMIT-TO ( PUBYEAR,2015) OR LIMIT-TO ( PUBYEAR,2014) OR LIMIT-TO ( PUBYEAR,2013) OR LIMIT-TO ( PUBYEAR,2012) OR LIMIT-TO ( PUBYEAR,2011) OR LIMIT-TO ( PUBYEAR,2010) ) AND ( LIMIT-TO ( DOCTYPE,"ar" ) ) AND ( LIMIT-TO ( LANGUAGE,"English" ) ) ) and PUBMED (phospholipase a2[Title] AND membranous nephropathy[Title] AND ("loattrfull text"[sb] AND ("2010/01/01"[PDAT] : "2018/12/31"[PDAT])). Fig. 1 outlines the breakdown of obtained manuscripts from the search for studies included in the review.
PRISMA BASED FLOW Records identified through MEDLINE searching (n= 86) Records identified through SCOPUS searching (n= 74) )
Records after duplicates removed (n= 83)
MEDLINE papers after automatic depuration (n= 80)
SCOPUS papers after automatic depuration (n= 42) Automatic Depuration Exclusion criteria • No non-English papers • No Meta-analysis and Systematic Reviews • No conference
papers and book chapters • No letters or
editorials
• No Article reviews • No any article type
before 2010 • No non-full-text Papers included in qualitative synthesis (n=43) Manual Depuration Exclusion Criteria
• With comorbidities, like kimura’s disease, sarchoidosis, hepatitis B Virus, graft-versus-host disease, etc…
• THSD7A-Abs
• Serum secretory phospholipase A2 group IB (sPLA2-IB)
• Polymorphisms (SNP’s) • Methods development papers • Letters or editorials not
excluded in automatic depuration
• Case reports
Results
In this study, 43 articles were critically analyzed for the clinical usefulness of PLA2R autoantibodies as a biomarker under various circumstances such as in the differential diagnosis with secondary forms of MN, disease activity, prognosis, therapeutic monitoring and risk estimation of post-transplant recurrence.
A large part of the included studies is of prospective nature. Nevertheless, the vast majority of their results are similar to retrospective studies. Regarding the size of the samples, we can also state that despite their heterogeneity, the results are mostly congruent except in a few cases [see table I].
Anti-PLA2R antibody detection was mostly performed using “conventional enzyme-linked immunosorbent assay” (ELISA). However, many studies also used indirect immunofluorescence test (PLA2R IIFT, Euroimmun) as a detection method. Western blot was used in few studies and mostly in order to compare and analyze the degree of agreement with other methods of Anti-PLA2R quantification [see table I].
All patients with MN included in the different clinical trials were previously diagnosed by renal biopsy [see table I].
The majority of the included studies used urinary protein excretion (g/day), serum creatinine (mg/dL), serum albumin (g/dL) and estimated glomerular filtration rate – eGFR (ml/min/1.73m2) as markers of renal function and disease activity.
All the authors presented results that demonstrated that the anti-PLA2R antibodies show a specificity superior to the sensitivity. However, these parameters are both unequivocally high for the diagnosis of IMN. [see table I].
Most studies that focused on the importance of these antibodies in monitoring disease activity showed that antibody values reflect disease activity.
Anti-PLA2R seronegative individuals have a spontaneous remission rate greater than those with circulating antibodies. [see table I]
Regarding to the usefulness of these antibodies in the therapeutic decision, seronegative individuals do not benefit from immunosuppressive therapy and anti-PLA2R pre-treatment values are not useful to predict response to pre-treatment. [see table I]. The rate of decline of antibodies after the institution of therapy seems to be the best parameter to evaluate the clinical response [see table I].
There is no consensus among the authors about the usefulness of these antibodies in assessing the risk of disease recurrence after renal transplantation. [see table I]
In the pediatric population, the sensitivity of this antibody is quite low compared to the adult population. [see table I]
Discussion
Many clinical trials investigated the usefulness of anti-PLA2R1 antibodies in the differential diagnosis with SMN and reached a consensus that these antibodies are almost pathognomonic of IMN, exhibiting an increased sensitivity and even a greater specificity [see table I]. However, it should be noted that the antibody quantification method, the cut-off values may have an influence on the levels of antibodies measured. Also, the inclusion of patients who have already started immunosuppression and those who are at an early stage of the disease may present false negatives. 21–27 The positivity of these
antibodies also does not totally exclude a secondary cause of MN, especially those who are more likely to develop malignancies.24
In an attempt to understand whether the levels of Anti-PLA2R antibodies are related to disease activity, several clinical trials have been conducted and most of them demonstrated that exists a linear correlation between anti-PLA2Rabs levels and clinical markers of renal function, especially proteinuria and serum albumin.26,28,37–41,29–36 The
results of the research carried out by Radice et al. showed that the probability of reduction of the proteinuria values by half increased 6.5-fold after the antibodies became negative, suggesting that antibody levels may represent the activity of the disease.41 However, Ardalan et al. did not obtain the same results, perhaps due to the small sample size of his
study.42
When analyzed the prognostic value of Anti-PLA2R antibodies, the majority of clinical trials revealed that seronegative IMN patients presented a higher rate of spontaneous remission when compared to those with circulating anti-PLA2R antibodies.15,23,28,29,34,37,43–45
Oh et al., did not obtain the same results as the other authors. The fact that western blot
(semiquantitative) was used as detection method and the confounding effect of the type of therapeutic regimen may have influenced the results.38
There is some controversy about the usefulness of these antibodies in therapeutic monitoring, and the studies included in this paper are quite heterogeneous from the point of view of study design and the results, but all assume that antibody levels may in the near future be an important weapon in delineating the therapeutic strategy as well as assessing the response to therapy and even predicting remission. In this sense, Hoxha et
probability of remission, when compared to those who only underwent supportive therapy.28 Two other studies reported that antibody levels prior to treatment were not
predictive of clinical response, while the relative reduction of antibodies after initiation of therapy correlates with time to remission and the likelihood of reaching it.The results of these studies are different from those published by Hoxha et al. who have concluded that anti-PLA2R titers are an independent risk factor for non-remission of disease. However, the analysis by Hoxha et al. includes all patients, treated and not treated with immunosuppression, in contrast with these studies which just include patients undergoing therapy. 35,46,47
Seitz-Polski et al., states that epitope spreading at baseline is an independent risk factor for non-remission and should be included in the therapeutic decision.48 The high
prevalence of alpha-enolase autoantibodies in these MN patients corroborates the previous assertion and its role as a facilitator of Anti-PLA2R access to podocytes requires more research.49 Also, the identification of the immunodominant epitope in PLA2R, a
complex consisting in cysteine- rich (CysR), fibronectin-like type II (FnII), and C-type lectin-like domain 1 (CTLD1) may provide in the future important clinical applications, especially in diagnosis and prognosis.50
Some authors have studied the glomerular expression of PLA2R, mainly with immunofluorescence and histochemistry, and found that it strongly correlates with levels of circulating Anti-PLA2R antibodies.29,33,34,51–53
Bi-positivity to anti-PLA2R antibodies and PLA2R antigen is correlated with an higher disease activity and lower remission compared to those who are only positive for PLA2R glomerular antigen and also the dual negativity of both is highly suggestive of secondary causes of MN.29,34,54
In addition to the high expression of PLA2R in renal tissue of IMN patients, the IgG4 expression is also elevated in these patients and may increase the discriminatory power between IMN and SMN.27,51,55–57 Yang et al. also argues that serum IgG4 monitoring is
more effective than the total antibody.58 Further studies are needed to understand whether
IgG4 may be a useful marker of MN.
There is some divergence regarding the usefulness of measuring antibodies at renal transplantation in order to assess the risk of recurrence of IMN. Two articles obtained results that do not support the correlation between the antibodies measured at the time of transplantation and the recurrence of the disease. On the other hand, Gutpta et al. obtained opposite results and stated that antibody titers> 29RU / mL predicted the recurrence of
IMN with high sensitivity and specificity. Contrary to other studies, the patients included in it have an identical regimen of immunosuppression. However, all these studies are retrospective and have reduced samples, so the generalization of results is compromised. Further prospective studies with larger samples are needed.18,59,60
With regard to the pediatric population, only 2 two clinical trials were included in this review, the percentage of Anti-PLA2R antibodies and renal PLA2R antigen expression is lower than the adult population. We can not say with certainty that PLA2R is the main target of pediatric IMN, since the included studies present small samples and there are still few studies.61,62
Conclusion
The positivity of the anti-PLA2R antibody in a patient with nephrotic syndrome is very suggestive of membranous nephropathy. However, distinguishing idiopathic form from secondary requires study of neoplasia and autoimmune diseases since in these cases these antibodies may be positive.
This new biomarker assumes an increasingly important role in the assessment of disease activity, risk of recurrence, therapeutic monitoring and evaluation of post-transplant recurrence, but its interpretation must be integrated with other markers of renal function. It is important that in the future there is a standardization of the values that define the seropositivity, as well as ranges of values that define the risk of recurrence according to the detection method used, in order to optimize the follow up.
The applicability of this marker in the pediatric population needs further investigation. More prospective studies are needed with larger samples, considering potential confounders.
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54. Segarra-Medrano A, Jatem-Escalante E, Quiles-Perez MT, Salcedo MT, Arbos-Via MA, Ostos H, et al. Prevalence, diagnostic value and clinical characteristics associated with the presence of circulating levels and renal deposits of antibodies against the M-type phospholipase A2 receptor in idiopathic membranous nephropathy. Nefrologia. 2014 May;34(3):353–9.
55. Yeo M-K, Kim YH, Choi DE, Choi S-Y, Kim K-H, Suh K-S. The Usefulness of Phospholipase A2 Receptor and IgG4 Detection in Differentiation Primary Membranous Nephropathy From Secondary Membranous Nephropathy in Renal Biopsy. Appl Immunohistochem Mol Morphol AIMM. 2018 Sep;26(8):591–8. 56. Liu H, Luo W, Gong S, Ding X. Detection and clinical significance of glomerular
M-type phospholipase A2 receptor in patients with idiopathic membranous nephropathy. Intern Med J. 2016 Nov;46(11):1318–22.
57. Hayashi N, Akiyama S, Okuyama H, Matsui Y, Adachi H, Yamaya 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.
58. Yang Y, Wang C, Jin L, He F, Li C, Gao Q, et al. IgG4 anti-phospholipase A2 receptor might activate lectin and alternative complement pathway meanwhile in idiopathic membranous nephropathy: an inspiration from a cross-sectional study. Immunol Res. 2016;64(4):919–30.
59. Seitz-Polski B, Payré C, Ambrosetti D, Albano L, Cassuto-Viguier E, Berguignat M, et al. Prediction of membranous nephropathy recurrence after transplantation by monitoring of anti-PLA2R1 (M-type phospholipase A2 receptor) autoantibodies: A case series of 15 patients. Nephrol Dial Transplant. 2014;29(12):2334–42.
60. Gupta G, Fattah H, Ayalon R, Kidd J, Gehr T, Quintana LF, et al. Pre-transplant phospholipase A2 receptor autoantibody concentration is associated with clinically significant recurrence of membranous nephropathy post-kidney transplantation. Clin Transplant. 2016;30(4):461–9.
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Appendix I – Table I
Author (year) Study type Patients (n) Anti-PLA2R1+ (n/%)
PLA2R expression %
Assay Diagnosis IMN Clinical outcome Hoxha et al.,201435 Prospective 133 NA NR ELISA
IIFT Renal Biopsy 81% reduction in anti-PLA2R1abs levels paralleled by a 39% reduction in proteinuria (disease activity).
Hoxha et al.,201431 Prospective 118 NA NR ELISA Renal Biopsy High anti-PLA2R1abs levels are associated with an accelerated loss of renal function. Hihara et al., 201627 Prospective 59 (38-IMN / 21
SMN) 50% IMN 0% SMN NR ELISA And CIIFA
Renal Biopsy Excellent specificity for the diagnosis of IMN, and anti-PLA2R positivity was associated with glomerular IgG4-dominant deposition. Qin et al., 201123 Prospective 106 (60-IMN /
56-SMN)
49/82% IMN 5/10,9% SMN
NR WB Renal Biopsy Detection of anti-PLA2R abs is a sensitive test (82%) for IMN and it was largely negative in SMN patients.
Xu et al., 201752 Retrospective 231 NA 189/81.8% IF Renal Biopsy Non-PLA2R-associated IMN respond more quickly to the immunosuppressive therapy compared with PLA2R-associated IMN. There were no differences in the assessment of renal function. Ardalan et al., 201342 Prospective 30 (23-IMN; 2-SMN; 5- other causes of NS) 17/74% IMN 0-SMN and other causes of NS
NR iIFA Renal Biopsy No correlation found between anti-PLA2Rabs and proteinuria level. Proteinuria is not a good marker of disease activity but may reflect the glomerular damage.
PLA2RAb > 29 RU/mL predict rMN with a sensitivity of 85% and a specificity of 92%. rMN patients without anti-PLA2Rabs should be studied for occult malignancy and different antigens.
Yang et al., 201658 Restropective 438 NA NR ELISA Renal Biopsy IgG4 levels has a higher accuracy of predicting clinical remission than total antibodies.
Zhang et al., 201721 Retrospective 172 cases 286 controls
1stcutoff: 84.06% (IMN) 2ndcutoff: 71.01%,(IMN)
NR TRFIA Renal Biopsy Serum anti-PLA2R-IgG levels are significantly higher in IMN patients than those with SMN.
Renal function is more altered in those with higher antibody titers.
Kim et., 201530 Prospective 160
(93-IMN; 14-SMN; 41-other
glomerulonephritis; 12- healthy controls)
41/44.1% NA ELISA
WB Renal Biopsy High levels of anti-PLA2RAbs are correlated with low remission rates and disease severity. . ELISA and WB have a concordance rate of 72.1% and a positive correlation (r = 0.590, p <0.001)
Hayashi et al., 201557
Prospective 25 16/73% NR ELISA Renal Biopsy PLA2R-related IMN patients have a lower remission rate and a worse clinical outcome than PLA2R-unrelated IMN patients. IgG4-dominant deposition greater in PLA2R related IMN
Song et al., 201837 Prospective 66 NA/52.1% NR ELISA Renal Biopsy Higher spontaneous remission in anti-PLA2R-negative patients.
Positive correlation between proteinuria and anti-PLA2R antibody level.
Incidence of Chronic kidney stage ≥3 is higher in anti-PLA2R positive patients. Jullien et al., 201744 Retrospective 68 NA NR ELISA Renal Biopsy Anti-PLA2Rabs vary in a dose-response manner with remission with spontaneous remission.
Anti-PLA2Rabs measured at diagnosis are not useful to predict disease activity. Radice et al. 201824 Prospective 479 sensitivity of
70.6% 178/252 iMN patients; 1/80 primary GN, 0/72 secondary GN; 9/32 sMN; 0/43 healthy controls
NR IIFT Renal Biopsy Anti-PLA2r positivity in a MN patient is not sufficient to exclude a secondary cause of MN, particularly in those who have a higher risk for malignancies.
Jatem Escalante et al., 201543
Restropective 55 NA NR ELISA Renal Biopsy Anti-PLA2R-negative patients are associated with greater number of spontaneous
remissions than anti-PLA2R-positive patient. Liu et al., 201851 Prospective 39 NA NR ELISA Renal Biopsy Serum anti-PLA2Rabs and PLA2R
expression in kidney tissue had a coincidence rate of 100%.
IMN patients revealed a kidney tissue expression of PLA2R and IgG4 about 88.89% and 81.84% respectively.
Limitation: reduced size sample Akiyama et al.,
31(SMN) without this condition. Positivity of anti-PLA2R is correlated with a greater number of patients with serum albumin </=3g/dL. Hoxha et al., 201528 Prospective 37 NA NR IIFT Renal Biopsy The use of immunosuppression or supportive
therapy doesn´t alter the probability to achieve remission in seronegative IMN patients.
Immunosuppressive therapy may not be necessary in seronegative patients. Qin et al., 201634 Retrospective 572 392/68.5% 519/90% ELISA -
anti-PLA2Rabs IF- glomerular phospholipase A2 receptor antigen
Renal Biopsy Patients who have bipositivy for anti-PLA2Rabs and PLA2R glomerular antigen have higher levels of proteinuria and they are in an unfavorable condition to achieve remission. Disease relapse and remission failure was greater in those who presented higher levels of PLA2R antigen deposition. Hoxha1et al., 201233 Prospective 88 60/68% 61 IIF Renal Biopsy No correlation found between proteinuria and
PLA2Rabs level.
There is a strong correlation between PLA2Rabs levels and a glomerular
expression of PLA2R in IMN patients, which may be useful in discriminating.
Medrano et. al
201546 Prospective 79 NA NR ELISA Renal Biopsy No correlation between antibody levels before treatment and clinical outcome. However, the relative reduction of antibodies has a predicted value higher than the absolute value of antibody reduction at 3- and 6-months post-treatment.
Dou et al., 201625 Prospective 229 NA NR ELISA Renal Biopsy Sensitivity/specificity of anti-PLA2R-Abs in the IMN diagnosis was: 65.3/97.3 %,
60.2/97.3 %, and 45.8/97.3 % for the different cutoff values (14, 20, and 40 RU/ml). AUC-0.87
A cutoff of 14 RU/ml should be used to diagnose IMN.
Ruggenenti et al.,
201545 Prospective 132 NA NR ELISA Renal Biopsy Anti-PLA2R antibody depletion preceded complete remission. Low anti-PLA2RAbs at baseline and full antibody depletion 6 months post-rituximab predicted remission.
Disease relapse was predicted bye resurgence of antibodies.
Kumar et al., 201562
Pediatric Prospective 5 3/60% 100% ELISA Renal Biopsy There seems to be a role for PLA2R in the pathogenesis of pediatric IMN but more studies are needed with larger samples. Seitz el al., 201459 Retrospective 15 NA NR ELISA Renal biopsy IgG4 anti-PLA2R1 positivity at the time of
transplant doesn’t predict recurrence. An active positivity IgG4 anti-PLA2R1 during follow-up(>6months) is a risk factor for recurrence. IgG4 anti-PLA2R1 titers may help in prediction of relapse disease.
Roy et al., 201753 Retrospective 190 NA NR IHC Renal biopsy Sensitivity of 70.2% and a specificity of 96.6% - Anti-PLA2R IHC is a specific marker for differential diagnosis between IMN and SMN.
Seitz-Polski et al.,
201848 Prospective 58 NA NR ELISA Renal biopsy Independently of anti-PLA2RAbs titers at baseline, sex, age and treatment group, epitope spreading predicts low probability of remission.
Wang et al. 201629 Retrospective 131 NA NR ELISA IIF- glomerular PLA2R
Renal biopsy There is a correlation between seronegatives and remission.
High titers of antibodies correlates with disease activity.
Bi-negativity of anti-PLA2Rabs and
glomerular PLA2R sugest seconday causes of MN
Yachha et al.,
201832 Prospective 63 NA/55.2% NR ELISA Renal biopsy There were higher titers of anti-PLA2Rabs in active disease. SMN patients were all seronegatives. There appears to be a proportional relationship between antibody levels and
disease activity-results tend to be significant. Seropositive patients presented worse state of hypoalbuminemia and proteinuria.
Segarra-Medrano et
al. 201447 Prospective 64 (IMN-47;SMN-17) Patients with anti-PLA2R deposits and anti-PLA2Rabs Sensivity 94.4%(IIF); 97.2%(ELISA) specificity-100% 76.6% IIF ELISA IHC- glomerular PLA2R
Renal biopsy No correlation found between Anti-PLA2Rabs titers (measured by ELISA) and proteinuria and albulinemia.
IF and ELISA have a high concordance a specifity.
Seropositive patients with Anti-PLA2R deposits have significantly proteinuria.
IMN patients Sensivity- 72.3% (IIF) and 74.5%(ELISA) Specificity 94.2%
Liu et al., 201656 Prospective 252 NA 82% IMN 16.7% SMN
IIF Renal biopsy Bipositivity (IgG4 and glomerular PLA2R deposits)-94.3% (IMN patients) and 50% (SMN patients)- can be useful to discriminate IMN and second forms of MN
Remission rate of proteinuria after
immunosuppressant therapy was greater in PLA2R positive group (83.9%) than negative group (54.5%).
Conclusion: IMN patients with positivity for glomerular PLA2R have a better response do immunosuprressant therapy.
Oh et al., 201338 Prospective 100 69/69% NR WB Renal biopsy Anti-PLA2Rabs levels correlate in a proportionally way with proteinuria and hypoalbulinemia (disease activity).
No correlation found between anti-PLA2Rabs levels and remission.
Debiec et al., 201118 Restrospective 19 NA NA IIF and WB Renal biopsy No correlation found between anti-PLA2Rabs levels at the time of transplantation and recurrence.
Lin et al., 201522 Retrospective 279 NA/60% NR ELISA Renal biopsy Sensitivty increase to 71.3% for those who didn’t receive immuno-suppression. AUC-0.80
Anti-PLA2Rabs levels correlate in a proportionally way with proteinuria and hypoalbulinemia (disease activity). Good diagnostic accuracy for IMN. Gopalakrishnan et
al., 201639 Prospective 75 (60-IMN; 15-SMN) 45/75% NR IIFT Renal Biopsy Specificity-100% Anti-PLA2Rabs levels correlate in a proportionally way with proteinuria and hypoalbulinemia (disease activity). Kimura et al.,
201749 Retrospective 169 NA/48% IMN 0%/SMN NR IIF- Anti-PLA2Rabs Dot blotting system Alpha-enolase antibodies
Renal Biopsy Prevalence of 70% of alpha-enolase
antibodies in IMN and SMN patients. Alpha-enolase was not found in glomerular deposits, in contrast with anti-PLA2R- These findings suggest that alfa enolase autoantibody may facilitate the access of other antibodies to the podocyte (ex-anti-PLA2R).
Kanda et al., 2017 61
Pediatric Retrospective 34 NA 6% SIM Renal biopsy The two patients with PLA2R positivity were older than 10 years. Glomerular granular staining is weaker in contrast witht IMN adult patients. These finding suggest that PLA2 has a limited role in pediatric IMN, especially in preteen and adolescent patients.
Limitation: small sample Wu et al., 201740 Retrospective 73 NA/85.4%
(IMN)
91.7% (IMN) 29.4%(SMN)
IIFT Renal biopsy Anti-PLA2Rabs levels and glomerularPLA2R correlate in a
29.4%(SMN) proportionally way with proteinuria and hypoalbulinemia (disease activity). Yeo et al., 201855 Retrospective 115 NA 83% IHC Renal biopsy PLA2R and IgG4 bipositivity showed a
specificity of 96.4% for IMN. This detection method can be useful to differentiate primary and second forms of MN.
Radice et al., 201641 Prospective 42 NA NR IIFT Renal biopsy Anti-PLA2Rabs levels correlate in a proportionally way with proteinuria and hypoalbulinemia.
The probability of proteinuria remission increased 6.5 times after antiPLA2Rabs becoming negative.
Evaluation of anti-PLA2R may be useful in optimizing immunosuppressive therapy, avoiding side-effects.
Segarra-Medrano et
al., 201447 Prospective 36 NA NR ELISA Renal biopsy No correlation between antibody levels before treatment and clinical outcome. Relative reduction of antibodies level was significantly greater in those who achieved remission.
Relative reduction in antibodies at 3 months predicted the response at 6 and 9 months, and the relative reduction at 6 months predicted the response at 12 months with high specificity and sensivity.
These findings suggest that antibody status can estimate the approximately time to achieve remission.
Kao et al., 201550 Prospective 74 NA NR NA NR Three-domain complex of PLA2R, consisting in cysteine- rich (CysR), fibronectin-like type II (FnII), and C-type lectin-like domain 1 (CTLD1) likes to be the Immunodominant Epitope.
Tampoia et al.,
Anti-PLA2Rabs levels and glomerularPLA2R correlate in a proportionally way with proteinuria,hypoalbulinemia and serum creatinine.
Abbreviations: AUC-Area under the ROC Curve; Anti-PLA2Rab- Anti-PLA2R antibodies; EM-Electron microscopy; IMN- Idiopathic Membranous Nephropathy; IHC – Immunohistochemistry; LM-Light microscopy; NR- Not reported; NA- Not applicable; NS- Nephrotic Syndrome; PCR-RFLP- Polymerase chain reaction-restriction fragment length polymorphism; rMN- Recurrence of Membranous Nephropathy; SIM-Standard immunofluorescence microscopy; SMN- Secondary Membranous Nephropathy; SNP-Single nucleotide polymorphisms; TRFIA - Time-resolved Fluoroimmunoassay;
Appendix II - Portuguese Journal of Nephrology and Hypertension:
Instructions to Authors
AIMS AND SCOPE
The Portuguese Journal of Nephrology and Hypertension is the official organ of the Portuguese Society of Nephrology and is published quarterly. Supplementary issues are also published including selected themes, at the discretion of the Editor-in-Chief, as well as abstracts of the annual congresses of the Society. The Journal is peer-reviewed and is indexed in Thompson Reuter’s SciELO Citation Index, with free online access in our website http://www.spnefro.pt/RPNH.
The Journal publishes articles on clinical or laboratory topics of relevance to nephrology, dialysis, transplantation and hypertension. Papers relating to basic immunology, physiology, genetics and epidemiology are accepted when kidney-related. Manuscripts must be submitted in English to the Editor-in-Chief. Only previously unpublished work should be submitted. The Editor-in-Chief has complete editorial freedom.
The Journal complies with the Uniform Requirements for Manuscripts Submitted to Biomedical Journals produced by the ICMJE (International Committee of Medical Journal Editors). Visit http://www.icmje.org REVIEW AND PUBLICATION SPEED All submissions will be subject to an immediate editorial screening process by the Editor-in-Chief after which they will normally be sent to two or three reviewers. The Editor-in-Chief will make every effort to reach a decision on all submitted papers within 8 weeks of receipt. Papers will normally be published in the next issue to go to press after their acceptance. Papers that do not meet the scientific standards of the Journal may be declined by the Editor-in-Chief without further review. CONTENT TYPES The Portuguese Journal of Nephrology and Hypertension publishes: 1) Editorials; 2) Review Articles; 3) Original Articles; 4) Case Reports; 5) Letters to the Editor; 6) Nephropathology Quiz; 7) Perspective; 8) Comments.
Editorials
Editorials are usually invited, but authors may propose a paper for the Editor-in-Chief’s consideration. They may have up to 2000 words and a maximum of 2 tables or figures. A maximum of 5 references is generally recommended.
Review Articles
Review articles should provide novel insights and comprehensive analyses of topics on Nephrology, and interpretation of the published literature. They are usually commissioned by the Editors. However, unsolicited reviews will be considered. These articles may have up to 5000 words and an
abstract of up to 300 words. The use of 3 tables or figures is acceptable. A maximum of 70 references is generally recommended. Original Articles An original article must focus on relevant clinical investigation or basic research, and is limited to 4000 words including an abstract with up to 300 words. The order of the text should be as follows: Introduction, Subjects and Methods (any statistical method must be detailed in this section), Results and Discussion. A maximum of 50 references is generally recommended. Case Reports
Original and succinct description structured in Introduction, Case Report and Discussion. They should not exceed 2500 words (including an abstract up to 300 words) and should not include more than 4 tables or figures. A maximum of 30 references is generally recommended.
Letters to the Editor
Letters must contain information related to an article published in the Journal or may concern a topic of current interest in Nephrology. Letters (maximum of 3 authors) are limited to 500 words and 1 table or figure. A maximum of 5 references is generally recommended. Nephropathology Quis A case report to educate clinicians on the renal pathology. This section includes a concise clinical history, images of histology and discussion. These articles are usually invited and are limited to 2000 words, 8 figures and 20 references. Perspective Perspective articles are brief, accessible pieces covering a wide variety of timely topics of relevance to health care and medicine. They are nearly always solicited, although unsolicited articles may occasionally be considered. Perspective articles are limited to 1000 to 1200 words and may include one figure or table. A maximum of 8 references is generally recommended. Comments Comments usually provide commentary and analysis concerning an article in the issue of the Journal in which they appear. They may also provide commentary concerning an article published elsewhere. They may include 1 figure or table. They are nearly always solicited, although unsolicited comments may occasionally be considered. Comments are usually limited to 1000 words, with up to 10 references.
INSTRUCTIONS FOR AUTHORS
Manuscripts must be submitted online http://rpnh.spnefro.pt. Once you have prepared your manuscript according to the Instructions below, please pay particular attention to the sections on Informed Consent and Ethics and Disclosure. The text should be double-spaced. The corresponding author should describe the contributions of all authors to the article. Manuscripts should bear the name, address and e-mail of the corresponding author.
Should the manuscript be accepted for publication the authors will be asked to give signed consent for publication in a letter which must contain the statement that “the results presented in this paper have not been published previously, in whole or in part, except in abstract form”.
Title Page: The title page should carry the full title of the paper and the first name, middle initial (if applicable) and last name of each author, plus the names and addresses of the respective institutions where the work was done; in the case of different institutions the author(s) should be identified using superscript Arabic numerals. Abstract: Not more than 300 words. Abbreviations should not be used. Key-Words: Not more than 6, in alphabetical order, and the terms used (when possible) should be from the Medical Subject Headings list of the Index Medicus. References: Authors are responsible for bibliographic accuracy. All the references, including those with only electronic sources, should be cited according to the “Vancouver Citation Style” which can be consulted on the Internet at: http://library.vcc.ca/downloads/VCC_VancouverStyleGuide.pdf References must be numbered consecutively in the order in which they are cited in the text. Each reference should give the name and initials of all authors unless they are more than six, when only the first three should be given followed by et al. Authors’ names should be followed by the title of the article, journal abbreviations according to the style used in Index Medicus, the year of publication, the volume number and the first and last page numbers. For papers in the course of publication, “in press” replaces the date; the journal name must be given in the references. Manuscripts that are unpublished, in preparation, or submitted, and personal communications should not be cited in the reference list but may appear parenthetically in the text. References to books should contain the author(s) name(s) and initials, the title of the book, followed by place of publication, publisher, year, and relevant pages. Websites must be referenced by the following order: title, URL and access date. Examples 1. Journals: Hogan J, Mohan P, Appel GB. Diagnostic tests and treatment options in glomerular disease: 2014 update. Am J Kidney Dis 2014;63(4):656-666 2. Books:
Morris Peter, Knechtle Stuart. Kidney Transplantation - Principles and Practice. 7th Edition.
Saunders, 2014:72
3. Website:
Substitutive Renal Therapy of Chronic Renal Disease in Portugal.
Available at http:www.spnefro.pt/comissoes_Gabinete_registo_2013/registo_2013. Accessed October 6, 2013.
4. Published Meeting Abstract:
Jorge Silva, Jorge Antunes, Telmo Carvalho, Pedro Ponce.
Efficacy of preventing hemodialysis catheter infections with citrate lock (Encontro Renal abstract SE001). Port J Nephrol Hypert 2011; 25(1):56
Tables: Tables should supplement, not duplicate, the information in the main text. References to tables should be made in order of appearance in the text and should be in Roman numerals in brackets, e.g. (Table II). Each table should be typed on a separate sheet and have a brief heading describing its contents. Figures: All illustrations (transparencies, photographs, diagrams, graphs, etc.) should be labelled consecutively in Arabic numerals (2...), according to their relative positions in the text. If a figure has been published before, the original source must be acknowledged and written permission from the copyright holder must be submitted with the material.
Informed Consent and Ethics: Identifying details of patients should not be published in descriptions unless the information is essential for scientific purposes and the patient gives written informed consent for publication. Patients shown in photographs should have their identity obscured or the picture must be accompanied by written permission to use the photograph.
When reporting experiments on human subjects, it is mandatory to indicate whether the procedures were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975 (revised in 2015) and, in the case of renal transplant, the Declaration of Istanbul.
When reporting experiments on animals, authors should indicate whether the institutional and national guide for the care and use of laboratory animals was followed. Disclosure: Each manuscript must include a conflict of interest statement before the References section. The disclosure statement will describe the sources of any support for the work in the form of grants, consulting fees or honoraria from industry, equipment, provision of drugs, travel related with the study or any combination thereof. Any relevant financial activities outside the submitted paper but considered stakeholders in the field must be detailed. The corresponding author should provide a Conflict of Interest Declaration describing the possible financial interests of all the authors. The absence of any interest must also be declared.
Acknowledgements should be located in the manuscript body before the conflict of interest statement.
