Membranous nephritis

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Overview

Membranous nephropathy (MN) or membranous glomerulonephritis (MGN) is a common glomerulonephritis that usually presents with nephrotic-range proteinuria, edema, and hypertension. MN is generally classified as primary (idiopathic) or secondary to other systemic disease, such as infections, malignancies, vasculitides etc. Primary MN has been recently associated with the presence of a newly discovered phospholipase A2 receptor (PLA2R) nephrotigenic antigen on the membrane surface of glomerular podocytes and anti-PLA2R antibodies. Kidney biopsy remains the gold standard for the diagnosis of MN, showing subepithelial deposits with capillary wall thickening and IgG deposition under immunofluorescence. While MN is widely considered a chronic condition with a waxing and waning course, it is usually self-limited in the majority of the cases. Heavy proteinuria, a significant marker of prognosis, indicates the need for intervention.

Historical Perspective

The term “membranous nephropathy” was first coined by Elexious T. Bell[1], a pathologist, in 1946 to describe a specific disease entity characterized by gradual-onset proteinuria and edema under Ellis type II glomerulonephritis, a classification by Arthur Ellis based on clinical and histopathological findings.[1] In 1957, David Jones used acid-silver methenamine, also known as Jones stain, to demonstrate that membranous nephropathy must be considered a unique glomerulonephritis due to the characteristic presence of capillary wall thickening and disruption of basement membrane.[2]

In 1959, Movat and McGregor used electron microscopy to identify subepithelial deposits in membranous nephropathy[3], based on earlier findings by Coons and Kaplan in 1950[4], Farquhar[5], and Mellors[6] in 1957.

It was not until 2009 when Beck and colleagues[7] discovered that antibodies against the nephritogenic phospholipase A2 receptor (PLA2R) is associated with the pathogenesis of the disease.

Epidemiology and demographics

Membranous nephropathy or membranous glomerulonephritis (MGN) has always been considered the most common glomerulonephritis associated with nephrotic syndrome, defined as severe proteinuria > 3.5 g/d, accounting for approximately 36% of cases.[8] Only recently, new data is suggesting that focal segmental Glomerulosclerosis (FSGS) may have surpassed MN as the leading cause of unexplained nephrotic syndrome.[8]

In general, MGN may be a disease of any age, any gender, and any ethnicity. However, the peak incidence of primary MN is between 40 and 50 years of age[9]; and it is very rarely seen in children. There is a slight male predominance to the disease and it is thought to be more common among Caucasian.[9] In 1996, Korbet and colleagues showed that among 340 patients with primary glomerulonephritis presenting with nephrotic syndrome over 20 years, MGN accounts for 24% of cases in African-American patients vs. 36% of cases in Caucasian patients.[10]

MGN is considered very rare in the pediatric population. Only 1-4% of all MGN is among children aged 1-12 years, and MGN comprises only 1.5% of all cases of nephrotic syndromes among children.[11][12] However, the incidence of MGN increases to 22% among patients aged 13-19 years.[12][13]

Secondary MGN, however, may have different age and geographic distributions.[14][15][16][17][18]

Among adult patients, most cases of MGN are idiopathic.[19] Only 20-30% of cases are due to secondary causes, such as infections, systemic illnesses, cancers, and medications in adults. (18235148). Secondary causes are in fact much more common in the pediatric age groups, reaching up to 35-75% of all cases of MGN.[20][11]

The majority of the patients present with mild proteinuria; but 60% of those eventually progress into nephrotic-range proteinuria within 1-2 years.

Pathophysiology

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Early description of the pathophysiology of the membranous nephropathy noted that the disease might be due to an auto-antibody production against an antigen on podocytes surfaces.[1][21][22] In 2009, Beck and colleagues[7] discovered that M-type phospholipase A2 receptor (PLA2R) protein as a nephritogenic antigen. It is currently believed that anti-PLA2R is present in approximately 80% of patients with primary membranous nephropathy[7][23][24][25][26] and to a much lesser extent in patients with secondary membranous nephropathy in patients, most notably in patients with hepatitis B and malignancies.[26] PLA2R1 is a 185-KDa glycoprotein expressed on the podocyte membrane surface.[7][27] Physiologically, its role has not been confirmed, but is presumed to be involved in the aging of the cell through the p53 pathway. It contains several characteristic domains[27]:

· E*Extracellular domain: Long domains with cysteine-rich head and a nephritogenic epitope at a methionine-rich terminal

*Fibronectin type II-like repeat domains

  • Repeated carbohydrate-recognition domains
  • Membrane-spanning domains

Intracellular domainsThe nephritogenic epitope in the extracellular domain is destroyed when the cysteine-cysteine disulfide bridges are disrupted.[7] Control of immune response by anti-PLA2R antibodies is controlled genetically by PLA2R1 gene locus at chromosome 2 and HLA-DQA1 and DQB1 on chromosome 6.[28] Peptides from PLA2R1 bind HLA-DQA1-expressing-antigen-presenting cells activate T cells and subsequently cause the production of antibodies, such as IgG4, by Th2 cytokine activation.[29][30][31] that contribute to clinical manifestations, such as proteinuria. The latter finding has been associated with unique molecular findings, such as formation of membrane attack complex (C5b-C9) and activation T-cell activation (CD8+).[29][30]


Presence of immunoglobulin subclass may have important pathological effects. · *IgG4: Associated with primary membranous nephropathy. It is presumed to have a “protective” effect when IgG1 is present because it acts against the formation of immune complexes.[22][32]

  • IgG1, IgG2, and IgG3: Associated with secondary membranous nephropathy. Their role seems to be pathogenic.[22][32]

The presence of anti-PLA2R has been correlated with clinical manifestations, prognosis, and recurrence of disease in membranous nephropathy.[33][34]

Several hypotheses have been postulated as to why a small number of patients with primary membranous nephropathy and the majority of those with secondary membranous nephropathy do not have detectable anti-PLA2R antibodies.[22] These factors are summarized as follows[22]:

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  • Poorly sensitive assays used for detection
  • Heterogeneous conformation of PLA2R epitope
  • Disappearance of antibodies spontaneously or due to treatment
  • Involvement of other nephritogenic antigens

Other antigens have been implicated in the disease and may have a role in the pathogenesis of membranous nephropathy. However, these antigens still require further validation.[22][23][24][35][36][37][38][39][40][41]:

  • Neutral endopeptidase
  • Superoxide dismutase
  • Aldose reductase
  • Alpha-enolase
  • Cationic serum albumin

Normal 0 false false false EN-US JA X-NONE

  • Renal tubular antigens (megalin)

·

Diagnosis

Membranous nephritis can be diagnosed by histological observation. Light microscopy with H&E stain may reveal thickened capillary walls. Fluorescence microscopy may reveal immunoglobulins in a granular pattern along the capillary wall. Jones (silver stain) may reveal spikes or holes corresponding to the immune deposits. Electron microscopy reveals electron dense deposits intramembranously or in the subepithelial space.

Prognosis

The prognosis for membranous nephritis is variable. In many cases, there is spontaneous remission. Therefore, many patients will not require treatment. However, in patients who have decreasing renal function and a high level of proteinuria (nephrotic range, and often around 10g), therapy using steroids and cytotoxics may be necessary. Cyclophosphamide and steroids have been used in some studies with success. In refractory cases, ciclosporin may also be useful. Some recent studies have tried mycophenolate mofetil with success.


References

Jha V, Ganguli A, Saha TK, Kohli HS, Sud K, Gupta KL, Joshi K, Sakhuja V. A randomized, controlled trial of steroids and cyclophosphamide in adults with nephrotic syndrome caused by idiopathic membranous nephropathy. J Am Soc Nephrol. 2007 Jun;18(6):1899-904. Template:WikiDoc Sources

  1. ↑ 1.0 1.1 1.2 Glassock RJ (2010). "The pathogenesis of idiopathic membranous nephropathy: a 50-year odyssey". Am J Kidney Dis. 56 (1): 157–67. doi:10.1053/j.ajkd.2010.01.008. PMID 20378220.
  2. ↑ JONES DB (1957). "Nephrotic glomerulonephritis". Am J Pathol. 33 (2): 313–29. PMC 1934622. PMID 13402889.
  3. ↑ MOVAT HZ, McGREGOR DD (1959). "The fine structure of the glomerulus in membranous glomerulonephritis (lipoid nephrosis) in adults". Am J Clin Pathol. 32 (2): 109–27. PMID 13670133.
  4. ↑ COONS AH, KAPLAN MH (1950). "Localization of antigen in tissue cells; improvements in a method for the detection of antigen by means of fluorescent antibody". J Exp Med. 91 (1): 1–13. PMC 2135948. PMID 15395569.
  5. ↑ FARQUHAR MG, VERNIER RL, GOOD RA (1957). "An electron microscope study of the glomerulus in nephrosis, glomerulonephritis, and lupus erythematosus". J Exp Med. 106 (5): 649–60. PMC 2136823. PMID 13475621.
  6. ↑ MELLORS RC, ORTEGA LG, HOLMAN HR (1957). "Role of gamma globulins in pathogenesis of renal lesions in systemic lupus erythematosus and chronic membranous glomerulonephritis, with an observation on the lupus erythematosus cell reaction". J Exp Med. 106 (2): 191–202. PMC 2136743. PMID 13449231.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Beck LH, Bonegio RG, Lambeau G, Beck DM, Powell DW, Cummins TD; et al. (2009). "M-type phospholipase A2 receptor as target antigen in idiopathic membranous nephropathy". N Engl J Med. 361 (1): 11–21. doi:10.1056/NEJMoa0810457. PMC 2762083. PMID 19571279.
  8. ↑ 8.0 8.1 Haas M, Meehan SM, Karrison TG, Spargo BH (1997). "Changing etiologies of unexplained adult nephrotic syndrome: a comparison of renal biopsy findings from 1976-1979 and 1995-1997". Am J Kidney Dis. 30 (5): 621–31. PMID 9370176.
  9. ↑ 9.0 9.1 Cattran DC (2001). "Idiopathic membranous glomerulonephritis". Kidney Int. 59 (5): 1983–94. doi:10.1046/j.1523-1755.2001.0590051983.x. PMID 11318974.
  10. ↑ Korbet SM, Genchi RM, Borok RZ, Schwartz MM (1996). "The racial prevalence of glomerular lesions in nephrotic adults". Am J Kidney Dis. 27 (5): 647–51. PMID 8629623.
  11. ↑ 11.0 11.1 Menon S, Valentini RP (2010). "Membranous nephropathy in children: clinical presentation and therapeutic approach". Pediatr Nephrol. 25 (8): 1419–28. doi:10.1007/s00467-009-1324-5. PMC 2887508. PMID 19908069.
  12. ↑ 12.0 12.1 Moxey-Mims MM, Stapleton FB, Feld LG (1994). "Applying decision analysis to management of adolescent idiopathic nephrotic syndrome". Pediatr Nephrol. 8 (6): 660–4. PMID 7696099.
  13. ↑ Kleinknecht C, Levy M, Gagnadoux MF, Habib R (1979). "Membranous glomerulonephritis with extra-renal disorders in children". Medicine (Baltimore). 58 (3): 219–28. PMID 449658.
  14. ↑ Abe S, Amagasaki Y, Konishi K, Kato E, Iyori S, Sakaguchi H (1986). "Idiopathic membranous glomerulonephritis: aspects of geographical differences". J Clin Pathol. 39 (11): 1193–8. PMC 1140761. PMID 3793935.
  15. ↑ Cahen R, Francois B, Trolliet P, Gilly J, Parchoux B (1989). "Aetiology of membranous glomerulonephritis: a prospective study of 82 adult patients". Nephrol Dial Transplant. 4 (3): 172–80. PMID 2498774.
  16. ↑ Zeng CH, Chen HM, Wang RS, Chen Y, Zhang SH, Liu L; et al. (2008). "Etiology and clinical characteristics of membranous nephropathy in Chinese patients". Am J Kidney Dis. 52 (4): 691–8. doi:10.1053/j.ajkd.2008.06.006. PMID 18805348.
  17. ↑ Lefaucheur C, Stengel B, Nochy D, Martel P, Hill GS, Jacquot C; et al. (2006). "Membranous nephropathy and cancer: Epidemiologic evidence and determinants of high-risk cancer association". Kidney Int. 70 (8): 1510–7. doi:10.1038/sj.ki.5001790. PMID 16941021.
  18. ↑ Gluck MC, Gallo G, Lowenstein J, Baldwin DS (1973). "Membranous glomerulonephritis. Evolution of clinical and pathologic features". Ann Intern Med. 78 (1): 1–12. PMID 4565900.
  19. ↑ Fervenza FC, Sethi S, Specks U (2008). "Idiopathic membranous nephropathy: diagnosis and treatment". Clin J Am Soc Nephrol. 3 (3): 905–19. doi:10.2215/CJN.04321007. PMID 18235148.
  20. ↑ Lee BH, Cho HY, Kang HG, Ha IS, Cheong HI, Moon KC; et al. (2006). "Idiopathic membranous nephropathy in children". Pediatr Nephrol. 21 (11): 1707–15. doi:10.1007/s00467-006-0246-8. PMID 16951933.
  21. ↑ Makker SP, Tramontano A (2011). "Idiopathic membranous nephropathy: an autoimmune disease". Semin Nephrol. 31 (4): 333–40. doi:10.1016/j.semnephrol.2011.06.004. PMC 3156416. PMID 21839366.
  22. ↑ 22.0 22.1 22.2 22.3 22.4 22.5 Glassock RJ (2012). "The pathogenesis of membranous nephropathy: evolution and revolution". Curr Opin Nephrol Hypertens. 21 (3): 235–42. doi:10.1097/MNH.0b013e3283522ea8. PMID 22388552.
  23. ↑ 23.0 23.1 Glassock RJ (2009). "Human idiopathic membranous nephropathy--a mystery solved?". N Engl J Med. 361 (1): 81–3. doi:10.1056/NEJMe0903343. PMID 19571287.
  24. ↑ 24.0 24.1 Ronco P, Debiec H (2010). "Antigen identification in membranous nephropathy moves toward targeted monitoring and new therapy". J Am Soc Nephrol. 21 (4): 564–9. doi:10.1681/ASN.2009121220. PMID 20185638.
  25. ↑ Ronco P, Debiec H (2010). "Membranous glomerulopathy: the evolving story". Curr Opin Nephrol Hypertens. 19 (3): 254–9. doi:10.1097/MNH.0b013e328336eafd. PMID 20110811.
  26. ↑ 26.0 26.1 Hofstra JM, Debiec H, Short CD, Pellé T, Kleta R, Mathieson PW; et al. (2012). "Antiphospholipase A2 receptor antibody titer and subclass in idiopathic membranous nephropathy". J Am Soc Nephrol. 23 (10): 1735–43. doi:10.1681/ASN.2012030242. PMC 3458465. PMID 22956816.
  27. ↑ 27.0 27.1 Lambeau G, Lazdunski M (1999). "Receptors for a growing family of secreted phospholipases A2". Trends Pharmacol Sci. 20 (4): 162–70. PMID 10322502.
  28. ↑ Stanescu HC, Arcos-Burgos M, Medlar A, Bockenhauer D, Kottgen A, Dragomirescu L; et al. (2011). "Risk HLA-DQA1 and PLA(2)R1 alleles in idiopathic membranous nephropathy". N Engl J Med. 364 (7): 616–26. doi:10.1056/NEJMoa1009742. PMID 21323541.
  29. ↑ 29.0 29.1 Cybulsky AV, Quigg RJ, Salant DJ (2005). "Experimental membranous nephropathy redux". Am J Physiol Renal Physiol. 289 (4): F660–71. doi:10.1152/ajprenal.00437.2004. PMC 1325222. PMID 16159900.
  30. ↑ 30.0 30.1 Penny MJ, Boyd RA, Hall BM (1998). "Permanent CD8(+) T cell depletion prevents proteinuria in active Heymann nephritis". J Exp Med. 188 (10): 1775–84. PMC 2212409. PMID 9815255.
  31. ↑ Kuroki A, Iyoda M, Shibata T, Sugisaki T (2005). "Th2 cytokines increase and stimulate B cells to produce IgG4 in idiopathic membranous nephropathy". Kidney Int. 68 (1): 302–10. doi:10.1111/j.1523-1755.2005.00415.x. PMID 15954921.
  32. ↑ 32.0 32.1 van der Zee JS, van Swieten P, Aalberse RC (1986). "Serologic aspects of IgG4 antibodies. II. IgG4 antibodies form small, nonprecipitating immune complexes due to functional monovalency". J Immunol. 137 (11): 3566–71. PMID 3782791.
  33. ↑ Hofstra JM, Beck LH, Beck DM, Wetzels JF, Salant DJ (2011). "Anti-phospholipase A₂ receptor antibodies correlate with clinical status in idiopathic membranous nephropathy". Clin J Am Soc Nephrol. 6 (6): 1286–91. doi:10.2215/CJN.07210810. PMC 3109923. PMID 21474589.
  34. ↑ Beck LH, Fervenza FC, Beck DM, Bonegio RG, Malik FA, Erickson SB; et al. (2011). "Rituximab-induced depletion of anti-PLA2R autoantibodies predicts response in membranous nephropathy". J Am Soc Nephrol. 22 (8): 1543–50. doi:10.1681/ASN.2010111125. PMC 3148709. PMID 21784898.
  35. ↑ Debiec H, Guigonis V, Mougenot B, Decobert F, Haymann JP, Bensman A; et al. (2002). "Antenatal membranous glomerulonephritis due to anti-neutral endopeptidase antibodies". N Engl J Med. 346 (26): 2053–60. doi:10.1056/NEJMoa012895. PMID 12087141.
  36. ↑ Prunotto M, Carnevali ML, Candiano G, Murtas C, Bruschi M, Corradini E; et al. (2010). "Autoimmunity in membranous nephropathy targets aldose reductase and SOD2". J Am Soc Nephrol. 21 (3): 507–19. doi:10.1681/ASN.2008121259. PMC 2831859. PMID 20150532.
  37. ↑ Bruschi M, Carnevali ML, Murtas C, Candiano G, Petretto A, Prunotto M; et al. (2011). "Direct characterization of target podocyte antigens and auto-antibodies in human membranous glomerulonephritis: Alfa-enolase and borderline antigens". J Proteomics. 74 (10): 2008–17. doi:10.1016/j.jprot.2011.05.021. PMID 21640210.
  38. ↑ Gitlits VM, Toh BH, Sentry JW (2001). "Disease association, origin, and clinical relevance of autoantibodies to the glycolytic enzyme enolase". J Investig Med. 49 (2): 138–45. PMID 11288754.
  39. ↑ Wakui H, Imai H, Komatsuda A, Miura AB (1999). "Circulating antibodies against alpha-enolase in patients with primary membranous nephropathy (MN)". Clin Exp Immunol. 118 (3): 445–50. PMC 1905442. PMID 10594566.
  40. ↑ Strauss J, Pardo V, Koss MN, Griswold W, McIntosh RM (1975). "Nephropathy associated with sickle cell anemia: an autologous immune complex nephritis. I. Studies on nature of glomerular-bound antibody and antigen identification in a patient with sickle cell disease and immune deposit glomerulonephritis". Am J Med. 58 (3): 382–7. PMID 46705.
  41. ↑ Debiec H, Lefeu F, Kemper MJ, Niaudet P, Deschênes G, Remuzzi G; et al. (2011). "Early-childhood membranous nephropathy due to cationic bovine serum albumin". N Engl J Med. 364 (22): 2101–10. doi:10.1056/NEJMoa1013792. PMID 21631322.
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