Glomeruloesclerosis Focal y Segmentaria en el Adulto Carlos Chiurchiu Servicio de Nefrología y Programa de Trasplantes Renales Hospital Privado-Centro Médico de Córdoba Córdoba, Argentina e-mail: cchiurchiu@hospitalprivadosa.com.ar

Esclerosis Focal Segmentaria - Es una lesión no un diagnóstico - Fisiopatología: Podocitopatía - Formas primarias dan lugar a secundarias - Grandes avances en la genética - Escasos avances en la terapéutica - Respuesta a esteroides: factor pronóstico

Causas de SN: Distribución racial

Incidencia de esclerosis: Subestimación con el analisis histopatológico convencional KI 1999 Analisis morfomètrico tridimensional

Clasificación Morfológica Consolidación con matriz EC obliterando el lumen capilar (variante perihiliar) Hipercel .endocapilar con oclusión del lumen (25 % del penacho) Lesión segmentaria próxima al origen del túbulo proximal Glomerulo colapsado Hipertrofia-Hiperplasia podocitaria

Significación de las Variantes Histológicas JASN 2004 In conclusion, the prognosis for nephrotic FSGS patients who enter remission is excellent regardless of the histologic lesion. Because the remission rate after treatment is similar among patients with the histologic variants, response to therapy cannot be predicted on the basis of histology alone. Thus, nephrotic patients with primary FSGS should receive a trial of therapy irrespective of the histologic lesion when not contraindicated. Pacientes que lograron remisión Pacientes que no lograron remisión

Significación de las Variantes Histológicas II KI 2006

Categorías Etiológicas de la GEFS Formas Idiopáticas (en disminución) Formas Genèticas Sindrómicas (Alport, Fabry, etc.) No sindrómicas (SNF, NPHS2 etc.) Formas Reactivas Postadaptativa (Obesidad, HTA, RVU) Drogas (CyA, Pamidronato, IFN) Infecciones (HIV, Parvo)

PATOGENESIS

Podocito Célula post-mitótica Altamente especializada Arquitectura única Funciones Permeselectividad Soporte estructural Remodelado de la MB Endocitosis proteica dependen de Slit diafragma Citoesqueleto de actina Medioambiente (MB) Señales bioquímicas

Patogénesis de GEFS: Modelos animales Nephrol Dial Transplant (2003)

Nephrol Dial Transplant (2003)

Nephrol Dial Transplant (2003)

Lesiones de GEFS son comunes en Nefropatía IgA Adhesiones: 72% (cohote:126) Adhesiones sin lesiones subyacentes: 41% Inmunohistoquímica: Cambia marcación de componentes podocitarios hacia componentes epiteliales parietales en lesiones mas severas

33 pacientes con recurrencia post Tx Edad: 29 años Altos valores de permeabilidad para albúmina Factor circulante: unión a prot A (50 Kd)

Factores Circulantes de Permeabilidad CJASN 2010 - Recurrencia de la proteinuria post-Tx - Respuesta a la plasmaferesis/inmunoabsorción - Inducción de proteinuria con infusión de plasma - Cardiotrophin-like cytokine-1 (CLC-1): Disminución expresión nefrina Niveles > 100 veces en pac con GEFS Soluble urokinase receptor (suPAR) Borramiento pies podocitarios VPF is a lymphokine that is elaborated by concanavalin A-stimulated T lymphocytes from patients with INS. VPF acts on systemic capillaries and on the glomerular permeability barrier (12). Its secretion is enhanced by IL-2, IL-15, IL-12, and IL-18 and is inhibited by TGF1. Hemopexin is a protease that activates protein kinase B and Rho A and induces nephrin-dependent reorganization of the actin cytoskeleton in cultured podocytes (Induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein loss via a mechanism that includes lipid-dependent activation of 53 integrin. Cardiotrophin-like cytokine-1 (CLC-1) in the active fraction from galactose affinity chromatography. CLC-1, a member of the IL-6 family, is the only cytokine present. Further studies suggest that CLC-1 may be the permeability factor in recurrent FSGS. It is present in active patient plasma, it mimics the effects of FSGS plasma on Palb, and it decreases nephrin expression by glomeruli and cultured podocytes. Strikingly, a monoclonal antibody to CLC-1 blocks the Palb effect of active FSGS sera. The concentration of CLC-1 in the circulation of patients with recurrent FSGS may be up to 100 times higher than in normal subjects

FORMAS GENÈTICAS DE GEFS CON EXPRESIÓN EN EL ADULTO

PODOCINA Intracitoplasmática Localización exclusiva en la región del slit Direccionamiento de la nefrina Formación del slit-diafragma

9/30 Familias estudiadas con mutaciones Formas primarias de GEFS (91 controles): 3,6% Mutations in NPHS2, encoding podocin, have been identified in childhood onset focal and segmental glomerulosclerosis (FSGS). The role of NPHS2 in adult disease is less well defined. We studied 30 families with FSGS and apparent autosomal recessive inheritance and 91 individuals with primary FSGS. We screened family members for NPHS2 mutations. NPHS2 mutations appeared to be responsible for disease in nine of these families. In six families, the affected individuals were compound heterozygotes for a nonconservative R229Q amino acid substitution. This R229Q variant has an allele frequency of 3.6% in a control population.

Edad media: 35 años Mutations in NPHS2, the gene that encodes podocin, are well-established causes of both familial and sporadic steroid-resistan (FSGS) in the pediatric population. Nearly all patients with NPHS2 homozygous or compound heterozygous mutations commonly present before the age of 6 yr. Only five families in which one or. Podocin, expressed exclusively in the glomerular podocyte, is an integral membrane protein located on the foot processes adjacent to the slit diaphragms that play a critical role in regulating hydraulic flow and protein filtration from the plasma space into the urinary space.8 Podocin interacts with other podocyte proteins, including recruiting nephrin to plasmamembrane lipid rafts,9 and CD2AP. more affected people presented after the age of 21 have been reportedt focal segmental glomerulosclerosis

Mutación de NPHS2 R229Q y microalbuminuria en población general RR = 2,77 A.Pereyra. KI 2004; 65: 1026

Steroid-resistant focal segmental glomerulosclerosis (FSGS) often recurs after renal transplantation. In this international survey, we sought to identify genotype–phenotype correlations of recurrent FSGS. We surveyed 83 patients with childhood-onset primary FSGS who received at least one renal allograft and analyzed 53 of these patients for NPHS2 mutations. The mean age at diagnosis was 6.7 years, and the mean age at first renal transplantation was 13 years. FSGS recurred in 30 patients (36%) after a median of 13 days (range, 1.5 to 152 days). Twenty-three patients received a second kidney transplant, and FSGS recurred in 11 (48%) after a median of 16 days (range, 2.7 to 66 days). None of the 11 patients with homozygous or compound heterozygous NPHS2 mutations developed recurrent FSGS compared with 45% of patients without mutations. These data suggest that genetic testing for pathogenic mutations may be important for prognosis and treatment of FSGS both before and after transplantation

INF2 gen que codifica Formina Proteína reguladora de actina Interacción con nefrina Screening de 54 familias con GSFS Mutaciones: 17% (78 pacientes) Controles: casos esporádicos de GSFS Mutaciones: 1 caso (84 pacientes) The recent identification of mutations in the INF2 gene, which encodes a member of the formin family of actin-regulating proteins, in cases of familial FSGS supports the importance of an intact actin cytoskeleton in podocyte function. To determine better the prevalence of INF2 mutations in autosomal dominant FSGS, we screened 54 families (78 patients) and detected mutations in 17% of them. In addition, we evaluated 84 sporadic cases but detected a mutation in only one patient. In conclusion, mutations in INF2 are a major cause of autosomal dominant FSGS. Because IQGAP1 interacts with crucial podocyte proteins such as nephrin and PLC1, the identification of mutations that may alter the putative INF2–IQGAP1 interaction provides additional insight into the pathophysiologic mechanisms linking formin proteins to podocyte dysfunction and FSGS

-La actinina mutada se une mas fuertemente a los filamentos - Actinina 4: proteína relacionada con los enlaces cruzados de los filamentos de actina -La actinina mutada se une mas fuertemente a los filamentos -Proteinuria moderada luego de la adolescencia - Lenta progresión a la IRC con GEFS Mutations in the -actinin-4 gene (ACTN4) can cause a slowly progressive form of kidney dysfunction characterized by mild to moderate proteinur These mutations increase the binding of ACTN4 to actin filaments as well as alter their intracellular localizationia, renal insufficiency with slow progression to ESRD, and a focal and segmental glomerulosclerotic pattern of tissue injury

Borramiento parcheado de los pies podocitarios Mutaciones de la actinina 4: 3,5% de GEFS familiar 1% de los esporádicos 27

Enfermedad agresiva Proteinuria masiva (3-4 década) ERCT: 60% Tiempo SN-ERCT: 10 años

Canales TRP: mecanosensación, homeostasis iónica, crecimiento celular e ingreso de Ca a la célula Genes mutados: cromosoma 11q21–22 and subsequently identified as the transient receptor potential cation channel, subfamily C, member 6 (TRPC6) gene The TRP channels are implicated in a variety of biologic functions, such as mechanosensation, ion homeostasis, cell growth, and PLC-dependent calcium entry into cells. The TRPC6P112Q mutation augments intracellular calcium influx into the podocyte, leading to FSGS through unclear mechanisms. My colleagues and I hypothesized that this results in disrupted glomerular cell function or causes apoptosis. Interestingly, stimulation by angiotensin II (AngII) also causes higher peak intracellular Ca

La activación del receptor muscarínico activa el canal TRPC6 en células neuronales La activación del canal se asocia con la formación de un complejo multiproteico El complejo mantiene estable el canal Participa de este complejo multiproteico la calcineurina

- MYH9 codifica cadena 9 de la miosina no muscular (miosina II) - Miosina II se une a actina (motilidad celular) MYH9 se expresa en podocitos, cel mesangiales y arteriolas MYH9 mutations had been implicated in a number of autosomal dominant syndromes: May-Hegglin, Sebastian, Fechtner, and Epstein. These syndromes are platelet disorders that are characterized by thrombocytopenia and leukocyte inclusions, with Fechtner and Epstein syndromes resulting in nephritis to varying degrees.

We identified a chromosome 22 region with a genome-wide logarithm of the odds (lod) score of 9.2 and a peak lod of 12.4 centered on MYH9, a functional candidate gene expressed in kidney podocytes. Multiple MYH9 SNPs and haplotypes were recessively associated with FSGS, most strongly a haplotype spanning exons 14 through 23 (OR = 5.0, 95% CI = 3.5–7.1; P = 4 × 10−23, n = 852). This association extended to hypertensive ESKD (OR = 2.2, 95% CI = 1.5–3.4; n = 433), but not type 2 diabetic ESKD (n = 476). Genetic variation at the MYH9 locus substantially explains the increased burden of FSGS and hypertensive ESKD among African Americans.

HIVAN 70 veces mas común en negros Evento tardío Mal pronóstico 20% de los homocig (E1) desarrollan HIVAN Forma de GEFS colapsante

Podocitos transgénicos: Aumento de proliferación espontánea, perdiendo inhibición de contacto Transgenic podocytes demonstrated increased spontaneous proliferation, compared with nontransgenic podocytes at confluence, and they were found to have a greater percentage of cells in the proliferative phase of the cell cycle. It is striking that transgenic podocytes were not contact inhibited and formed aggregates in soft agar. Aggregates also formed when nontransgenic podocytes were infected with the identical HIV-1 construct used to generate the transgenic model. This demonstrates that the loss of contact inhibition is due to a direct effect of HIV-1. Therefore, proliferation induced by HIV-1 gene expression is likely to play a key role in the pathogenesis of HIVAN.

FORMAS REACTIVAS

All patients developed FSGS lesions of classic type (not otherwise specified), but only switched patients exhibited advanced sclerotic lesions. Immunohistochemistry showed that some podocytes in FSGS lesions had absent or diminished expression of the podocyte-specific epitopes synaptopodin and p57, reflecting dedifferentiation, and had acquired expression of cytokeratin and PAX2, reflecting a immature fetal phenotype. Such a pattern of epitope expression provides evidence for podocyte dysregulation. Moreover, a decrease in vascular endothelial growth factor expression was observed in some glomeruli. In conclusion, sirolimus induces FSGS that is responsible for proteinuria in some transplant patients.

Here clinicopathologic findings are reported for a distinctive population of seven patients, who were older, Caucasian, and HIV negative and developed collapsing FSGS during active treatment of malignancy (multiple myeloma in six patients and metastatic breast carcinoma in one). Although oncologic treatment regimens included vincristine for four patients, doxorubicin for five patients, cisplatin for two patients, and total-body irradiation for one patient, the only agent common to all patients was pamidronate (Aredia). All patients had normal renal function before the administration of pamidronate. Patients began therapy with pamidronate at or below the recommended dose of 90 mg, intravenously, monthly, which was increased to 180 mg monthly in two patients and 360 mg monthly in three patients. Patients received pamidronate for 15 to 48 mo before presentation with renal insufficiency (mean serum creatinine, 3.6 mg/dl) and full nephrotic syndrome (mean 24-h urinary protein excretion, 12.4 g/d).

Proteinuria (mean 10.1 g/d; range 1.3 to 26.3 g/d) Renal insufficiency (creatinine 3.0 mg/dl; range 1.3 to 7.8) Three (30%) patient presented with nephrotic syndrome. Anabolic steroid abuse adversely affects the endocrine system, blood lipids, and the liver, but renal injury has not been described. We identified an association of focal segmental glomerulosclerosis (FSGS) and proteinuria in a cohort of 10 bodybuilders (six white and four Hispanic; mean body mass index 34.7) after long-term abuse of anabolic steroids. The clinical presentation included proteinuria (mean 10.1 g/d; range 1.3 to 26.3 g/d) and renal insufficiency (mean serum creatinine 3.0 mg/dl; range 1.3 to 7.8 mg/dl); three (30%) patients presented with nephrotic syndrome. Renal biopsy revealed FSGS in nine patients, four of whom also had glomerulomegaly, and glomerulomegaly alone in one patient. Three biopsies revealed collapsing lesions of FSGS, four had perihilar lesions, and seven showed 40% tubular atrophy and interstitial fibrosis. Among eight patients with mean follow-up of 2.2 yr, one progressed to ESRD, the other seven received renin-angiotensin system blockade, and one also received corticosteroids. All seven patients discontinued anabolic steroids, leading to weight loss, stabilization or improvement in serum creatinine, and a reduction in proteinuria. One patient resumed anabolic steroid abuse and suffered relapse of proteinuria and renal insufficiency. We hypothesize that secondary FSGS results from a combination of postadaptive glomerular changes driven by increased lean body mass and potential direct nephrotoxic effects of anabolic steroids. Because of the expected rise in serum creatinine as a result of increased muscle mass in bodybuilders, this complication is likely underrecognized

Respuesta a los esteroides en formas de GEFS del adulto KI 2002

Mutations in the NPHS2 gene represent a frequent cause of SRNS, occurring in approximately 20 to 30% of sporadic cases of SRNS

El efecto antiproteinúrico de los anticalcineurínicos Mathieson P. N Engl J Med 2008

Reducción del 50% en ClCr: 25% GT y 52% GC (p<0.05) KI 1999 Edad promedio 39 años Caucásicos: 87% Creat: 1,4 mg/dl Proteinuria . 7-8 g/día 26 semanas de Trat. Placebo (n:23) CyA (n: 26) Todos con esteroides CyA: 3,5 mg/Kg/día Niveles: 125-225 ng/dl Reducción del 50% en ClCr: 25% GT y 52% GC (p<0.05)

*Grupo MMF recibió mitad dosis: 0.5 mg/kg/día Edad promedio 31 años MDRD: 84 ml/min Proteinuria . 4,7 g/día 26 semanas de Trat. Control (n:17) MMF (n: 16) Todos con esteroides* MMF: 2 g/día Methods. We compared the efficacy of an MMF-based therapy with standard therapies in inducing remission in adult nephrotics with MN and FSGS in a randomized pilot study. MMF was given at 2 g/day for 6 months along with prednisolone at 0.5 mg/kg/day for 2–3 months. Conventional therapy was prednisolone 1 mg/kg/day for 3–6 months for FSGS and alternating monthly cycles of steroids and cyclophosphamide for 6 months for MN. The primary end point was change in urinary protein/creatinine ratio. Results. A total of 54 patients (21 MN and 33 FSGS) were recruited; 28 were randomized to receive MMF (group A) and 26 were on conventional treatment (group B). There was no difference in the proportion of patients achieving remission in two groups (64 and 80% in MN and 70 and 69% in FSGS). The frequency of relapses and incidence of infections was also similar. FSGS patients in group A achieved remission faster and received a lower cumulative steroid dose. Conclusions. A 6-month treatment with MMF is as effective as the conventional treatment for primary treatment of MN and FSGS in the short term. It induces remission faster and reduces steroid exposure in FSGS patients. Studies with more cases and longer follow-up are required to evaluate its impact on preservation of kidney function. *Grupo MMF recibió mitad dosis: 0.5 mg/kg/día

Background and objectives: Isolated case reports have shown a beneficial effect of rituximab on pediatric patients with primary FSGS, but there is no information about rituximab treatment of FSGS in adults. Design, setting, participants, & measurements: All patients who had biopsy-proven FSGS and were treated with rituximab in Spain were identified, independent of their positive or negative response, among the nephrology departments that belong to the Spanish Group for the Study of Glomerular Diseases (GLOSEN). Their characteristics and outcome after rituximab treatment were studied. Results: Eight patients were identified. Rituximab failed to improve nephrotic syndrome in five of eight patients, who continued to show massive proteinuria and exhibited a rapidly deteriorating renal function in two cases. Among the remaining three patients, two of them showed an improvement of renal function and a remarkable proteinuria reduction and one experienced a beneficial but transitory effect after rituximab. There were no differences in clinical or laboratory characteristics or in the CD20 B lymphocyte count after rituximab between these three patients and the five who had a negative response. The only difference was in the regimen of rituximab administration: Whereas the five patients with a negative response received only four weekly consecutive infusions of 375 mg/m2, the three remaining patients received additional doses of rituximab. Conclusions: Only a minority (three of eight) of patients in our series of adult patients with FSGS showed a positive influence of rituximab. More studies are necessary to characterize further the optimal dosages and the mechanisms of action of rituximab in FSGS.

Muchas Gracias