MCNS: no changes under light microscopy. No signs of inflammation, immune complex deposition or schlerosis. FSGS: collapse of the glomerular capillaries with sclerosis and hyalinosis and the formation of adhesions of the glomerular tuft
recent genetic approaches to familial idiopathic nephrotic syndromes have been determining factors in elucidating several molecular aspects of focal glomerular sclerosis
These proteins include molecules that locate at the slit diaphragm (nephrin, neph1, podocin, CD2AP and the Src family kinase Fyn), transcription factors (WT-1, Lmx1B, Pod1 and Krml1/MafB), cytoskeletal components (α-actinin-4 and RhoGDIα), adhesion molecules (α3 integrin) and components of the GBM (S-laminin/laminin β2) 1. a contractile system composed of actin, myosin-II, -actinin-4, talin, vinculin and synaptopodin that is connected to the GBM via 31 integrin. 2. The linkage of the actin cytoskeleton to the slit diaphragm components, nephrin and P-cadherin, may be mediated by CD2AP or by a complex of ZO-1, -, - and -catenin. 3. The localization of podocin in the podocyte cell membrane remains to be established. The actin cytoskeleton is well suited to integrate different signalling pathways from the matrix:GBM interface, the slit diaphragm or the cell surface. Disruption of any of these pathways may lead to reorganization of the actin cytoskeleton and foot process effacement as seen with nephrotic syndrome. N, nephrin; P-C, P-cadherin; , -catenin; , -catenin; , -catenin; Z, ZO-1; 3, 3-integrin; 1, 1−integrin; V, vinculin; T, talin; P, paxillin; -act-4, -actinin-4; synpo, synaptopodin. http://images.google.com/imgres?imgurl=http://www.nature.com/ng/journal/v24/n4/thumbs/ng0400_333_F3.gif&imgrefurl=http://www.nature.com/ng/journal/v24/n4/full/ng0400_333.html&h=84&w=150&sz=7&hl=en&start=1&tbnid=20SvGpeqTACs9M:&tbnh=54&tbnw=96&prev=/images%3Fq%3Dactinin%2Bpodocyte%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG There’s been studies which show that nephrin may be involved in MCD but to date most genetic and animal models have shown FSGS
Clinical observations… -MCD frequently remits with measles infection (viral-associated immunosuppresion) -the therapeutic benefits of steroids and cyclophosphamide which abate cell-mediated responses -and the occurrence of this syndrome in Hodgkin&apos;s disease support this hypothesis. Taken together, the data suggest that this syndrome is a clinical expression of a self-limited primary immune-deficiency disease. Experimental observations… Clinical observations suggest that lipoid nephrosis is produced by a systemic abnormality of T-cell function resulting in the secretion of a circulating chemical mediator toxic to an immunologically innocent glomerular basement membrane. In study by Koyama, where T cell hybridomas was derived from the T cells of a patient with MCD, and injection of supernatants from the T-cell hybridoma from patients in relapse into rats caused immediate proteinuria and glomerular podocyte foot process fusion, where as no changes were ntoed when the T-cell hybridoma supernatants from healthy controls was fused. - ideal of glomerular permeability factor (GPF). - The molecular weight of the factor and its TNF like activity, we speculated that the factor was a lymphokine, like lymphotoxins. This is supported by intriguing observation that transplantation of a kidney from a patient with refractory MCD resulted in rapid disappearance of proteinuria in the recipients.
Mean 24-h urine albumin excretion (mg/24 h) of control rats (n = 17) and IL-13–transfected rats (n = 41) measured at 14-d intervals. Data are means ± SEM.
Immunofluorescence examination showed that nephrin, podocin, and dystroglycan all stained strongly as a continuous granular pattern along the GBM in the control rats. This was in contrast to the nephrotic rats, in which the fluorescence signal was much weaker and in a discontinuous, and sometimes segmental, granular pattern along the GBM Of note, there was no significant difference between the control and nephrotic rats in the expression of synaptopodin, which showed strong and continuous staining along the GBM. In FSGS usually podocytopenia results where there’s decrease in the number of podocyte 2/2 stress, injury, intrinsic factor. IN MCD, there’s a phenotypic change with decrease in absolute no of podocyte.
…. , because the glomerular expression of WT-1 and synaptopodin, which are specific cell surface markers of podocytes, showed no significant difference between the control rats and the IL-13–transfected rats
Innate Immune function reduced inflammatory response attenuate expression of adhesion molecules on endothelial and leukocytes (via inhibition of IL-1 and TNF) = thereby inhibiting transmigration of leukocytes Inhibiting generation of inflammatory exudates Suppressing production of inflammatory eicosanoids in phagocytic cells by inducing the synthesis of lipocortin-1 (annexin I), macrocortin, and/or lipomodulin, all of which inhibit phospholipase A2 (PLA2)-mediated liberation of arachidonic acid from membrane phospholipids [9-12]. Suppressing the synthesis of cyclooxygenase-2 (COX-2), the inducible isoform of cyclooxygenase primarily responsible for production of prostaglandins at sites of tissue injury and inflammation . This effect primarily results from glucocorticoid suppression of NF-kB transcription. Glucocorticoids do not appear to affect the synthesis of constitutive cyclooxygenase-1 Inflammatory response: -attenuate expression of adhesion molecules on endothelial and leukocytes -attenuate the generation of inflammatory exudates
Study of dexamethasone on FSGS but can be translated to MCD?
We found that dexamethasone enhanced and accelerated podocyte maturation, with a particularly striking effect on expression of nephrin Nephrin expression was upregulated after 14 days incubation with dexamethasone (Figure 2). Immunofluorescent staining is not regarded as a quantitative technique, but there is a striking difference in the amount of fluorescence seen in images taken on identical exposure settings with anti-nephrin rabbit polyclonal antibody K2966 according to the presence or absence of dexamethasone in the culture medium for 14 days (Figure 2a, no dexamethasone, Figure 2b, cells incubated with 10-5 M, Figure 2c negative control immunofluorescence with rabbit immunoglobulin (Ig) for comparison). Quantitation by Western blot with rabbit polyclonal anti-nephrin antibody K2737 confirmed dose-dependent upregulation of nephrin protein by dexamethasone (Figure 2d, representative of five replicate experiments). Nephrin is a large-molecular-weight membrane-bound protein and is known to be difficult to blot, accounting for the indistinct bands. We therefore show detailed densitometric quantification of three replicate Western blots, which showed nephrin/actin ratios of 1.0:1.33:1.618 with 0, 10-7, and 10-5 M dexamethasone, respectively (P&lt;0.05, Figure 2e). Reverse transcriptase-polymerase chain reaction (RT-PCR) suggested that this effect was at least partly at the RNA level (Figure 2f, representative of five replicate experiments). Expression of other key podocyte proteins, including podocin,5CD2-associated protein,7 and synaptopodin10 was unaffected by dexamethasone (data not shown).
Podocytes’s capacity for replication Role of p21 Upregulated in diseases characterized by podocyte injury Enhanced podocyte survival p21 downregulation allow podocyte to enter the cell cycle – enhance ability to repair VEGF, a mitogen for vascular endotheila cells downregulated Upregulated in MCD
Minimal Change Disease,Minimal Change Disease,
Some new updates!Some new updates!
Deepti Torri M.DDeepti Torri M.D
North Shore-LIJ NephrologyNorth Shore-LIJ Nephrology
Hofstra Medical SchoolHofstra Medical School
Most common cause of the nephrotic syndrome inMost common cause of the nephrotic syndrome in
children, MCD contributes to 90 % of cases.children, MCD contributes to 90 % of cases.
~10-15% of nephrotic syndrome in adults, third most~10-15% of nephrotic syndrome in adults, third most
common after MN and FSGScommon after MN and FSGS
More common in Hispanics, Asians, Arabs and CaucasiansMore common in Hispanics, Asians, Arabs and Caucasians
clinical and pathologicalclinical and pathologicalentity defined by selectiveentity defined by selective
proteinuria and hypoalbuminemiaproteinuria and hypoalbuminemiathat occurs in thethat occurs in the
cellular glomerular infiltratescellular glomerular infiltratesoror
immunoglobulin depositsimmunoglobulin deposits
Pathogenesis - “Intrinsic factor”Pathogenesis - “Intrinsic factor”
Genetic basis for hereditary NSGenetic basis for hereditary NS
NS of the Finnish typeNS of the Finnish type
Autosomal-recessive steroid-resistant NSAutosomal-recessive steroid-resistant NS
Familial forms of FSGSFamilial forms of FSGS
Diffuse mesangila sclerosis associated with Denys-DrashDiffuse mesangila sclerosis associated with Denys-Drash
syndrome and with Frasier syndromesyndrome and with Frasier syndrome
NS associated with nail-patella syndromeNS associated with nail-patella syndrome
Help elucidate molecular aspect of FSGSHelp elucidate molecular aspect of FSGS
Not clear for MCDNot clear for MCD
Molecular anatomy of the podocyteMolecular anatomy of the podocyte
foot process cytoskeletonfoot process cytoskeleton
Nature Genetics 24, 333 - 335 (2000)
Pathogenesis – extrinsic factor,Pathogenesis – extrinsic factor,
better explanation for MCDbetter explanation for MCD
Clinical Observations - Shalhoub’s hypothesisClinical Observations - Shalhoub’s hypothesis
MCD frequently remits with measles infectionMCD frequently remits with measles infection
Corticosteroids and alkylating drugs cause a remissionCorticosteroids and alkylating drugs cause a remission
Association of MCD with Hodgkin diseaseAssociation of MCD with Hodgkin disease
Experimental ObservationsExperimental Observations
T cell hybridoma (Koyama KI 1991 (40): 453-460)T cell hybridoma (Koyama KI 1991 (40): 453-460)
Removal of glomerular permeability factor leads to normalRemoval of glomerular permeability factor leads to normal
kidney (Ali Transplantation 1994 Oct 15;58(7):849-52)kidney (Ali Transplantation 1994 Oct 15;58(7):849-52)
““circulating factor”circulating factor”
possible link between T-cell response and glomerularpossible link between T-cell response and glomerular
Overexpression of Interleukin-13Overexpression of Interleukin-13
Induces Minimal-Change–Induces Minimal-Change–
Like Nephropathy in RatsLike Nephropathy in Rats
MCD may be a T cell dependentMCD may be a T cell dependent disorder thatdisorder that
results in glomerular podocyte dysfunctionresults in glomerular podocyte dysfunction
Th2 cytokine bias in patients with MCDTh2 cytokine bias in patients with MCD
MCD associated with atopy and allergyMCD associated with atopy and allergy
Relapse MCD with elevated IL-4 and IL-13Relapse MCD with elevated IL-4 and IL-13
Association between MCD and Hodgkins’s diseaseAssociation between MCD and Hodgkins’s disease
IL-13 known to be an autocrine growth factorIL-13 known to be an autocrine growth factorfor thefor the
JASN 18 : 1476-1485,2007
IL-13 may play an important role in theIL-13 may play an important role in the
development ofdevelopment ofproteinuria in MCNS byproteinuria in MCNS by
exerting a direct effect on podocytes,exerting a direct effect on podocytes,actingacting
through the IL-13 receptors on the podocyte cellthrough the IL-13 receptors on the podocyte cell
surface,surface,initiating certain signaling pathways thatinitiating certain signaling pathways that
eventually lead toeventually lead tochanges in the expression ofchanges in the expression of
podocyte-related proteins (nephrin, podocin,podocyte-related proteins (nephrin, podocin,
and dystroglycan)and dystroglycan)
IL-13 transfected rat was used as a modelIL-13 transfected rat was used as a model
Mean 24-h urine albuminMean 24-h urine albumin
excretion (mg/24 h)excretion (mg/24 h)
IL 13 n =41
Comparison of control, IL-13-transfectedComparison of control, IL-13-transfected
mouse at experiment end (day 70)mouse at experiment end (day 70)
ParameterParameter Control RatsControl Rats
Group 1Group 1
rats), n=34rats), n=34
Grp 2: neprhroticGrp 2: neprhrotic
rats n=7rats n=7
Serum albuminSerum albumin 42.7 +/- 1.842.7 +/- 1.8 40.7 +/- 1.340.7 +/- 1.3 25.5 +/- 2.225.5 +/- 2.2
Urine albuminUrine albumin 0.36 +/- 0.040.36 +/- 0.04 3.19 +/- 0.983.19 +/- 0.98 9.69 +/- 4.079.69 +/- 4.07
Serum cholesterolSerum cholesterol 1.72 +/- 0.051.72 +/- 0.05 2.68 +/- 0.182.68 +/- 0.18 6.88 +/- 1.096.88 +/- 1.09
Serum IL-13Serum IL-13 7.1 +/- 1.87.1 +/- 1.8 241.4 +/- 69.5241.4 +/- 69.5 708.6 +/- 257.7708.6 +/- 257.7
NephrinNephrin 0.16 +/- 0.030.16 +/- 0.03 0.11 +/- 0.010.11 +/- 0.01 0.01 +/- 0.0050.01 +/- 0.005
PodocinPodocin 0.25+/- 0.050.25+/- 0.05 0.17 +/- 0.020.17 +/- 0.02 0.01 +/- 0.0050.01 +/- 0.005
Yellow = p <0.001 vs control Red = p<0.001 vs control and Grp 1
Histopathologic features on dayHistopathologic features on day
70 at killing70 at killing
(A) Glomerulus of(A) Glomerulus of IL-13IL-13–transfected–transfected
rat showing no significant histologicrat showing no significant histologic
changes (periodic acid-Schiff stain).changes (periodic acid-Schiff stain).
(B) Glomerulus of(B) Glomerulus of IL-13IL-13–transfected–transfected
rat showing fusion of podocyte footrat showing fusion of podocyte foot
processes (arrows).processes (arrows).
(C) Glomerulus of control rat showing(C) Glomerulus of control rat showing
normal individual podocyte footnormal individual podocyte foot
processes along the glomerularprocesses along the glomerular
basement membrane (GBM; arrows).basement membrane (GBM; arrows).
Immunofluorescence staining ofImmunofluorescence staining of
glomeruli for protein expressionglomeruli for protein expression
of nephrin, podocin,of nephrin, podocin,
dystroglycan, and synaptopodindystroglycan, and synaptopodinnephrin
Control IL-13 infected
IL-13-transfected ratsIL-13-transfected rats
Developed minimal change like GN, as evidence byDeveloped minimal change like GN, as evidence by
LM and EM changesLM and EM changes
decrease in the expression of nephrin, podocin,decrease in the expression of nephrin, podocin, andand
dystroglycan associated with increased urinarydystroglycan associated with increased urinary
albumin excretion and podocytealbumin excretion and podocytefoot processfoot process
suggesting that these proteins aresuggesting that these proteins areessential in maintainingessential in maintaining
the filtration barrier, thus controllingthe filtration barrier, thus controlling glomerularglomerular
decrease was not due to loss ofdecrease was not due to loss ofpodocytes -podocytes -
How does steroid work in MCD?How does steroid work in MCD?
Widely used in treatment but their mode ofWidely used in treatment but their mode of
action is poorly understoodaction is poorly understood
What is its effectiveness in MCD where there isWhat is its effectiveness in MCD where there is
no evident inflammationno evident inflammation
Steroid – quick overviewSteroid – quick overview
Inhibitory effects on both innate and acquiredInhibitory effects on both innate and acquired
immunologic functionimmunologic function
Innate Immune functionInnate Immune function
Reduced Inflammatory response:Reduced Inflammatory response:
inhibit transmigration of leukocytesinhibit transmigration of leukocytes
attenuate the generation of inflammatory exudatesattenuate the generation of inflammatory exudates
Phospholipase A2 suppresionPhospholipase A2 suppresion
COX-2 suppressionCOX-2 suppression
Acquired Immune functionAcquired Immune function
Antigen presenting cells, B cell and T cellsAntigen presenting cells, B cell and T cells
Treatment - GlucocorticoidsTreatment - Glucocorticoids
Glucocorticoid therapy remains the mainstay ofGlucocorticoid therapy remains the mainstay of
treatment with complete remission in 75-97% of adultstreatment with complete remission in 75-97% of adults
with MCD.with MCD.
There is only one randomized control treatment trial inThere is only one randomized control treatment trial in
adults with MCD that compared prednisone with noadults with MCD that compared prednisone with no
therapy (n=31).therapy (n=31).
- 75 % of prednisone treated patients had remission to75 % of prednisone treated patients had remission to
<1g/day of proteinuria within 6 months.<1g/day of proteinuria within 6 months.
- In the untreated group, 50% were in remission at 18In the untreated group, 50% were in remission at 18
months and approximately 70% at three years.months and approximately 70% at three years.
There are no randomized control trials comparingThere are no randomized control trials comparing
prednisone to other agents for the initial therapy inprednisone to other agents for the initial therapy in
adults with MCD.adults with MCD.
Black DA et al. BMJ 3:p421, 1970.
Treatment - GlucocorticoidsTreatment - Glucocorticoids
StudyStudy Korbet et alKorbet et al
Nolasco etNolasco et
alal Mak et alMak et al
Fujimoto etFujimoto et
Nakayama etNakayama et
Waldman etWaldman et
Number ofNumber of
PatientsPatients 4040 8989 5151 3333 6262 9595 401401
RemissionRemission 98%98% 91%91% 92%92% 97%97% 98%98% 92%92% 95%95%
CompleteComplete 91%91% 78%78% 76%76% 97%97% 93%93% 75%75% 95%95%
PartialPartial 7%7% 13%13% 16%16% 5%5% 17%17%
ResistanceResistance 2%2% 9%9% 8%8% 3%3% 2%2% 8%8% 5%5%
Initial response to steroids (1-1.5mg/kg/day) in adult onset minimal change
Complete remission defined as < 0.3 g/d of proteinuria.
Partial remission defined as >50% reduction of proteinuria from baseline.
Glucocorticoid Treatment ResponseGlucocorticoid Treatment Response
There were no features at presentation that predicted aThere were no features at presentation that predicted a
response (or lack thereof) to steroids.response (or lack thereof) to steroids.
Responders tended to have a slightly lower serumResponders tended to have a slightly lower serum
creatinine at presentation compared withcreatinine at presentation compared with
nonresponders but this was not statistically significantnonresponders but this was not statistically significant
(1.3 vs 1.6mg/dl).(1.3 vs 1.6mg/dl).
Of note, seven steroid resistant patients underwentOf note, seven steroid resistant patients underwent
repeat biopsy in the Waldman study, FSGS wasrepeat biopsy in the Waldman study, FSGS was
identified in six cases. (whether the diagnosis of FSGSidentified in six cases. (whether the diagnosis of FSGS
was missed on initial biopsy or there was progression towas missed on initial biopsy or there was progression to
FSGS is uncertain).FSGS is uncertain).
Waldman et al. CJASN 2: p445, 2007.
Study Korbet et al Nolasco et al Mak et al
Patients 40 89 51 33 62 95 401
65% 76% 70% 37% 62% 73% 71%
16% 26% 27% 44%
40% 14% 50% 10% 18%
Relapse defined as resumption of nephrotic range proteinuria (>3.5 g/d).
Frequent relapsers defined as >3 relapses in 1 year period.
Steroid dependent defined as relapse upon tapering steroid therapy or within 4
weeks of discontinuation of steroids.
Second Line TreatmentSecond Line Treatment
For frequent relapsers and steroid-dependent patients.For frequent relapsers and steroid-dependent patients.
No prospective treatment trials, all retrospectiveNo prospective treatment trials, all retrospective
observational reports.observational reports.
Both cyclophosphamide and cyclosporine reported toBoth cyclophosphamide and cyclosporine reported to
induce and maintain remission in up to 60% of MCDinduce and maintain remission in up to 60% of MCD
patients, less so in steroid resistant cases (10%).patients, less so in steroid resistant cases (10%).
Cyclosporine tends to achieve a more rapid remission, butCyclosporine tends to achieve a more rapid remission, but
between 60-90% of patients relapse after discontinuationbetween 60-90% of patients relapse after discontinuation
making cyclosporine dependence a major issue.making cyclosporine dependence a major issue.
Meyrier A et al. NDT 18:p vi79, 2003.
Ponticelli et al. KI 43:p1377, 1993.
Second Line TreatmentSecond Line Treatment
Although small retrospective case series have usedAlthough small retrospective case series have used
azathioprine, mycophenolate mofetil, and tacrolimus,azathioprine, mycophenolate mofetil, and tacrolimus,
the data is very limited.the data is very limited.
- An immunomodulator which enhances antibodyAn immunomodulator which enhances antibody
production and phagocytic activity of PMNs andproduction and phagocytic activity of PMNs and
monocytes, has been used in children with frequentmonocytes, has been used in children with frequent
relapses and steroid-dependence with increasing ratesrelapses and steroid-dependence with increasing rates
of steroid free remissions.of steroid free remissions.
- A few case reports in adults suggesting possible role inA few case reports in adults suggesting possible role in
the treatment of MCD.the treatment of MCD.
Korbet etKorbet et
et alet al Mak et alMak et al
et alet al
PatientsPatients 4040 8989 5151 3333
up (mo)up (mo)
5454 9191 169169 4646
20%20% 6%6% 2%2% 3%3%
ESRDESRD 5%5% 1%1% 2%2%
DeathDeath 8%8% 17%17% 2%2% 3%3%
Complications of nephroticComplications of nephrotic
syndrome have beensyndrome have been
reported in 21% of adults inreported in 21% of adults in
long term follow uplong term follow up
- Thrombotic events 13%Thrombotic events 13%
- Life threatening infectionsLife threatening infections
- Myocardial infarction 9%Myocardial infarction 9%
Mortality rate is higher inMortality rate is higher in
adults as compared toadults as compared to
children which ischildren which is
approximately 3%.approximately 3%.
Could steroid have more directCould steroid have more direct
effect in kidney?effect in kidney?
Direct effects of dexamethasone onDirect effects of dexamethasone on
human podocyte – Xing, Saleem, et alhuman podocyte – Xing, Saleem, et al
Glucocorticoid exert direct protection of podocytesGlucocorticoid exert direct protection of podocytes
from injury and/or promotion of repairfrom injury and/or promotion of repair
Nephrin: podocyte specific proteinNephrin: podocyte specific protein
mutation of NPHS2 gene - cause congenital nephrotic syndromemutation of NPHS2 gene - cause congenital nephrotic syndrome
of Finnish typeof Finnish type
Studies show possible downregulation of nephrin in MCDStudies show possible downregulation of nephrin in MCD
KI (2006) 70, 1038-1045
Result – effects of dexamethasone onResult – effects of dexamethasone on
podocyte maturation at 37 C andpodocyte maturation at 37 C and
expression of nephrinexpression of nephrin
Dexamethasone enhanced and acceleratedDexamethasone enhanced and accelerated
podocyte maturation, with a particulary strikingpodocyte maturation, with a particulary striking
effect on expression of nephrineffect on expression of nephrin
Other steroid responseOther steroid response
In disease stateIn disease state With dexamethasoneWith dexamethasone
p21p21 UpregulatedUpregulated downregulation allowdownregulation allow
podocyte to enter the cellpodocyte to enter the cell
cycle – enhance ability tocycle – enhance ability to
VEGFVEGF a mitogen fora mitogen for
vascular endotheilavascular endotheila
p52p52 Induces apoptosisInduces apoptosis downregulateddownregulated