Adenocarcinoma de pulmón con doble mutación del receptor del factor de crecimiento epidérmico (exón 19 y T790M) de novo: ¿Predictor de resistencia? / Lung adenocarcinoma with double mutation of the epidermal growth factor receptor (exon 19 and T790M) de novo: Predictor of resistance?

La mutación del receptor del factor de crecimiento epidérmico (EGFR) en los tumores de pulmón puede observarse en un 10-47% de pacientes. El 90% de las mutaciones son deleciones del exón 19 o mutaciones puntuales del L858R del exón 21, y se asocian a respuesta con inhibidores de tirosina quinasa (TKI). La mutación predictora de resistencia a TKI más frecuente es la T790M en el cromosoma 20, y puede observarse en un 50% de los pacientes expuestos a TKI (mutación secundaria, principal mecanismo de resistencia a TKI) y en menos del 5% de los pacientes de novo. La presencia de mutación T790M de novo concomitante con mutaciones sensibles (doble mutación) es poco frecuente y se cree que podría expresar menor sensibilidad a los TKI. Se presenta un caso clínico correspondiente a una mujer portadora de una doble mutación (deleción exón 19 y T790M) de novo, que fue tratado con erlotinib en primera línea, presentando respuesta objetiva por 10 meses. En el caso descripto, portador de una doble mutación, la respuesta a erlotinib en primera línea fue similar a la comunicada en pacientes con mutaciones predictoras de respuesta (AU)

EGFR mutation in NSCLC has been reported in 10-47% of patients. 90% of these mutations are deletions in exon 19 or point mutations of L858R in exon 21, and are associated to TKI response. T790M is the most common (50%) emerging mutation after first line TKI therapy, associated with resistance. Although this mutation has been reported before TKI therapy (de novo) its prevalence is less than 5%. Concomitant de novo sensitizing and resistance mutations (double mutation) is extremely unlikely, it could be associated with less sensitivity. We describe a patient with a de novo double mutation (deletion exon 19 and T790M) who was treated with erlotinib in first line with objective response lasting 10 months. Our patient, harboring a double mutation had a response to first line erlotinib lasting the same as the median progression free survival reported in patients with sensitizing mutations (AU)

Experiencia monoinstitucional en carcinoma de pulmón de células no pequeñas con reordenamiento EML4-ALK / Monoinstitutional experience in non-small cell lung carcinoma with EML4-ALK rearrangement

El gen de fusión EML4-ALK es producto de la inversión dentro del brazo corto del cromosoma 2 que da lugar a una proteína quimérica con actividad tirosinquinasa y oncogénica. EML4-ALK está presente en una pequeña proporción de pacientes con carcinoma no microcítico de pulmón (aproximadamente el 5%), principalmente en histología de adenocarcinoma y ausencia de hábito tabáquico. De 2012 a 2016 se analizó el reordenamiento EML4-ALK en 340 casos en nuestro centro. Se analizaron los pacientes con el reordenamiento por sexo, edad, hábito tabáquico, estadio diagnóstico, sitios metastásicos, respuesta al tratamiento y tiempo del mismo con inhibidores específicos. Del análisis de 340 casos, se detectó el reordenamiento EML4-ALK en 22 (6.4%), 10 de ellos de sexo masculino, edad promedio 52.4 años (23 a 86 años), 13 no tabaquistas, 13 con enfermedad metastásica al diagnóstico. De estos 22, 15 iniciaron tratamiento con crizotinib, presentando 10 de ellos beneficio clínico, con un tiempo promedio de tratamiento de 18 meses. Entre los pacientes con re arreglo cromosómico ALK, 2/22 casos presentaron concomitantemente la mutación ALK más la del gen EGFR, ambos en posición L858R del exon 21. El reordenamiento EML4-ALK es una condición infrecuente, vista generalmente en pacientes con adenocarcinoma, aunque puede presentarse en pacientes con carcinoma indiferenciado o epidermoide; en tres encontramos alteraciones del EGFR, de distinta significancia clínica. El tratamiento con inhibidores específicos es bien tolerado, con alta tasa de respuesta y beneficio clínico prolongado (AU)

The fusion oncogene EML4-ALK, results by a small inversion in the short arm region of chromosome 2, resulting in a chimeric protein with tyrosine kinase and oncogenic activity. EML4-ALK was found in a small proportion of patients with non-small cell lung carcinoma (about 5%), mainly in adenocarcinoma histology and never on light smokers. Between 2012 and 2016 we evaluated EML4-ALK rearrangement in 340 patients in our center. We analized sex, age, smoke habit, tumoral stage, metastasic sites, treatment response and treatment duration with specific inhibitors. Of 340 cases, the EML4-ALK rearrangement was found in 22 (6.4%), all diagnosed with adenocarcinoma, 10 of them male, mean age 52.4 years (23-86 years), 13 were nonsmokers and 13 with metastatic disease at diagnosis. The 15 patients started treatment with crizotinib, 10 of them presented clinical benefit (stable disease or partial response) and an average treatment time of 18 months; 2/22 patients with ALK mutations had concomitant in the EGFR gene, both L858R mutation in exon 21. The EML4-ALK rearrangement is a rare condition, which is usually seen in patients with adenocarcinoma and no history of smoking;although our experience with the use of specific inhibitors is limited, this treatment appears to be well tolerated with prolonged clinical responses (AU)

Hereditary nonpolyposis colorectal cancer (Lynch Syndrome) in Argentina: report from a referral hospital register.

PURPOSE: The first Argentine experience with epidemiologic, molecular, and genetic counseling data is reported. METHODS: We analyzed 43 families fulfilling Amsterdam criteria identified from a prospective database with data from 779 relatives. RESULTS: Eleven families (25.6 percent) presented as Lynch I, 29 (67.4 percent) as Lynch II, and 3 (7 percent) as Muir-Torre syndrome. Among the 306 affected members, 197 cases of colorectal cancer were identified (mean age at diagnosis, 52.1 (range, 21-90) years). The most frequent extracolonic tumors were gastric adenocarcinoma in males and endometrium adenocarcinoma in females. A high incidence of breast cancer was observed (16 cases among 155 females, crude rate: 11,594.20/100,000). Twenty-seven patients (8.8 percent) developed more than one tumor. These patients were younger than those with only one tumor (45 vs. 51 years; P = 0.001). In 5 of 11 patients who underwent molecular sequencing, a pathologic mutation was found. A novel C deletion at 1910 nucleotide, codon 637, exon 12 of MSH2 gene was identified in a family with a strong aggregation of breast cancer with lack of MSH2 immunohistochemical staining. For 78.2 percent of counseled individuals, this session represented the first time they received information, and 73.9 percent stated that their physicians were unaware of their family background. CONCLUSIONS: Argentine families presented a high incidence of stomach cancer. The elevated incidence of breast cancer and its association with a novel hMSH2 mutation bring to consideration the inclusion of this malignancy as part of the syndrome. A lack of awareness by both physicians and persons at risk was observed.

[Immunohistochemical expression and microsatellite instability in Lynch syndrome]. / Expresion inmunohistoquimica e inestabilidad microsatelital en el sindrome de Lynch.

Mutation of the mismatch repair genes MLH1 and MSH2 account for the majority of the genetic abnormalities in Lynch syndrome. Immunohistochemical detection of their protein products is becoming an increasingly common method to detect these mutations. The aim of this study was to compare the expression of MLH1 and MSH2 by immunohistochemistry and its relationship with a group of clinical and histological variables in patients with known Lynch syndrome (n=16) and in cohort of young patients (less than 50 years) who did not meet Amsterdam criteria (n=25). The mean age was 40.7 and 64% were women. Conclusive results were obtained in 40 cases (97.6%). Eighteen cases (45%) showed abnormal expression of either MLH1 (11 cases) or MSH2 (6 cases) and both stains (1 case). Alteration of the normal staining pattern was seen more commonly in patients with Lynch syndrome than in the sporadic group (68.7% vs 28%, p=0.01). A significant correlation was obtained between abnormal protein expression and microsatellite instability (MSI): normal expression: 5.9%, lack of expression: 92.3%, p<0.0001. The sensitivity and specificity of the immunohistochemical to predict MSI were 92.3% and 94.1% respectively. Immunohistochemistry and MSI results did not correlate with any histopathological parameter. In conclusion, in our experience abnormal staining of MLH and MSH correlates strongly with the presence of MSI. In addition it appears that in our population a significant proportion of young patients (< 50 years old) demonstrate alterations in the mismatch repair gene products suggesting an important role of these molecules in tumorigenesis.

Expresion inmunohistoquimica e inestabilidad microsatelital en el sindrome de lynch / Immunohistochemical expression and microsatellite instability in Lynch syndrome

Las mutaciones de los genes MLH1 y MSH2 son frecuentemente implicadas en el síndrome de Lynch. La expresión inmunohistoquímica (IHQ) es una forma simple de selección para pruebas moleculares. Se analizó la IHQ de MLH1 y MSH2 en pacientes con síndrome de Lynch (16 casos) y pacientes menores de 50 años sin antecedentes familiares (25 casos). Se estudiaron 41 tumores de un grupo de pacientes (64% mujeres) de edad promedio 40.7 años (rango: 16-75). Se obtuvieron resultados concluyentes en 40 casos (97.6%). Dieciocho casos (45%) presentaron falta de expresión (MLH1 negativa: 11 casos; MSH2 negativa: 6 casos; MLH1 negativa y MSH2 negativa: 1 caso), con una incidencia significativamente mayor en pacientes con síndrome de Lynch (68.7% vs. 28%, p=0.01). Entre los casos esporádicos, 5 casos (20%) mostraron falta de expresión MLH1 y 2 casos (8%) con falta de expresión MSH2. La falta de expresión IHQ presentó una fuerte asociación con inestabilidad microsatelital alta (IMS): expresión normal: 5.9%, expresión negativa: 92.3%, P<0.0001. Los índices de sensibilidad y especificidad de la IHQ para detectar IMS fueron de 92.3% y 94.1% respectivamente. Los patrones de IHQ y de IMS no se relacionaron a ninguna característica histopatológica. En conclusión, el análisis inmunohistoquímico de las proteínas MLH1 y MSH2 fue altamente sensible y específico para detectar IMS y permitió identificar en un 45% de los casos la proteína alterada. El índice de falta de expresión IHQ entre los casos esporádicos diagnosticados antes de los 50 años justifica su implementación sistemática en este grupo de pacientes.

Mutation of the mismatch repair genes MLH1 and MSH2 account for the majority of the genetic abnormalities in Lynch syndrome. Immunohistochemical detection of their protein products is becoming an increasingly common method to detect these mutations. The aim of this study was to compare the expression of MLH1 and MSH2 by immunohistochemistry and its relationship with a group of clinical and histological variables in patients with known Lynch syndrome (n=16) and in cohort of young patients (less than 50 years) who did not meet Amsterdam criteria (n=25). The mean age was 40.7 and 64% were women. Conclusive results were obtained in 40 cases (97.6%). Eighteen cases (45%) showed abnormal expression of either MLH1 (11 cases) or MSH2 (6 cases) and both stains (1 case). Alteration of the normal staining pattern was seen more commonly in patients with Lynch syndrome than in the sporadic group (68.7% vs 28%, p=0.01). A significant correlation was obtained between abnormal protein expression and microsatellite instability (MSI): normal expression: 5.9%, lack of expression: 92.3%, p<0.0001. The sensitivity and specificity of the immunohistochemical to predict MSI were 92.3% and 94.1% respectively. Immunohistochemistry and MSI results did not correlate with any histopathological parameter. In conclusion, in our experience abnormal staining of MLH and MSH correlates strongly with the presence of MSI. In addition it appears that in our population a significant proportion of young patients (< 50 years old) demonstrate alterations in the mismatch repair gene products suggesting an important role of these molecules in tumorigenesis.

Expresion inmunohistoquimica e inestabilidad microsatelital en el sindrome de lynch / Immunohistochemical expression and microsatellite instability in Lynch syndrome

Las mutaciones de los genes MLH1 y MSH2 son frecuentemente implicadas en el síndrome de Lynch. La expresión inmunohistoquímica (IHQ) es una forma simple de selección para pruebas moleculares. Se analizó la IHQ de MLH1 y MSH2 en pacientes con síndrome de Lynch (16 casos) y pacientes menores de 50 años sin antecedentes familiares (25 casos). Se estudiaron 41 tumores de un grupo de pacientes (64% mujeres) de edad promedio 40.7 años (rango: 16-75). Se obtuvieron resultados concluyentes en 40 casos (97.6%). Dieciocho casos (45%) presentaron falta de expresión (MLH1 negativa: 11 casos; MSH2 negativa: 6 casos; MLH1 negativa y MSH2 negativa: 1 caso), con una incidencia significativamente mayor en pacientes con síndrome de Lynch (68.7% vs. 28%, p=0.01). Entre los casos esporádicos, 5 casos (20%) mostraron falta de expresión MLH1 y 2 casos (8%) con falta de expresión MSH2. La falta de expresión IHQ presentó una fuerte asociación con inestabilidad microsatelital alta (IMS): expresión normal: 5.9%, expresión negativa: 92.3%, P<0.0001. Los índices de sensibilidad y especificidad de la IHQ para detectar IMS fueron de 92.3% y 94.1% respectivamente. Los patrones de IHQ y de IMS no se relacionaron a ninguna característica histopatológica. En conclusión, el análisis inmunohistoquímico de las proteínas MLH1 y MSH2 fue altamente sensible y específico para detectar IMS y permitió identificar en un 45% de los casos la proteína alterada. El índice de falta de expresión IHQ entre los casos esporádicos diagnosticados antes de los 50 años justifica su implementación sistemática en este grupo de pacientes.(AU)

Mutation of the mismatch repair genes MLH1 and MSH2 account for the majority of the genetic abnormalities in Lynch syndrome. Immunohistochemical detection of their protein products is becoming an increasingly common method to detect these mutations. The aim of this study was to compare the expression of MLH1 and MSH2 by immunohistochemistry and its relationship with a group of clinical and histological variables in patients with known Lynch syndrome (n=16) and in cohort of young patients (less than 50 years) who did not meet Amsterdam criteria (n=25). The mean age was 40.7 and 64% were women. Conclusive results were obtained in 40 cases (97.6%). Eighteen cases (45%) showed abnormal expression of either MLH1 (11 cases) or MSH2 (6 cases) and both stains (1 case). Alteration of the normal staining pattern was seen more commonly in patients with Lynch syndrome than in the sporadic group (68.7% vs 28%, p=0.01). A significant correlation was obtained between abnormal protein expression and microsatellite instability (MSI): normal expression: 5.9%, lack of expression: 92.3%, p<0.0001. The sensitivity and specificity of the immunohistochemical to predict MSI were 92.3% and 94.1% respectively. Immunohistochemistry and MSI results did not correlate with any histopathological parameter. In conclusion, in our experience abnormal staining of MLH and MSH correlates strongly with the presence of MSI. In addition it appears that in our population a significant proportion of young patients (< 50 years old) demonstrate alterations in the mismatch repair gene products suggesting an important role of these molecules in tumorigenesis.(AU)

A sexual dimorphism in intrathymic sialylation survey is revealed by the trans-sialidase from Trypanosoma cruzi.

Sialylation is emerging as an important issue in developing thymocytes and is considered among the most significant cell surface modifications, although its physiologic relevance is far from being completely understood. It is regulated by the concerted expression of sialyl transferases along thymocyte development. After in vivo administration of trans-sialidase, a virulence factor from the American trypanosomatid Trypanosoma cruzi that directly transfers the sialyl residue among macromolecules, we found that the alteration of the sialylation pattern induces thymocyte apoptosis inside the "nurse cell complex." This suggests a glycosylation survey in the development of the T cell compartment. In this study, we report that this thymocyte apoptosis mechanism requires the presence of androgens. No increment in apoptosis was recorded after trans-sialidase administration in females or in antiandrogen-treated, gonadectomized, or androgen receptor mutant male mice. The androgen receptor presence was required only in the thymic epithelial cells as determined by bone marrow chimeric mouse approaches. The presence of the CD43 surface mucin, a molecule with a still undefined function in thymocytes, was another absolute requirement. The trans-sialidase-induced apoptosis proceeds through the TNF-alpha receptor 1 deathly signaling leading to the activation of the caspase 3. Accordingly, the production of the cytokine was increased in thymocytes. The ability of males to delete thymocytes altered in their sialylation pattern reveals a sexual dimorphism in the glycosylation survey during the development of the T cell compartment that might be related to the known differences in the immune response among sexes.

Síndrome de Lynch: implementación ideal del diagnóstico genético / Lynch syndrome: ideal implementation of the genetic diagnosis

Las pruebas genéticas tienen una aplicación creciente en los síndromes de cánceres hereditarios, de los cuales el cáncer colorrectal hereditario no polipósico (Síndrome de Lynch); es el más frecuente. Este se caracteriza por el desarrollo de adenocarcinoma colorrectal a temprana edad con alta incidencia de tumores sincrónicos y metacrónicos así como la asociación con tumores extracolónicos. Su herencia es autosómica dominante y es consecuencia de la mutación germinal de los genes reparadores hMLH1, hMSH2, hMSH6, hPMS1 ó hPMS2. Diferentes pruebas genético-moleculares pueden ser utilizadas para su diagnóstico, pero se logra identificar la mutación sólo entre el 15 y 60 por ciento de los casos. Dada la complejidad inherente a la utilización de la información genética en afectados y familiares, se recomienda que la misma se efectúe en el marco de un asesoramiento genético realizado por grupos multidisciplinarios. Objetivo: Comunicar nuestra experiencia sobre el asesoramiento genético basado en determinaciones moleculares a través de un programa especializado. Material y método: Se confeccionó un árbol genealógico oncológico con datos de 68 personas pertenecientes a una familia, seguida desde 1982, que cumplía con los criterios de Amsterdam. Cada uno de los 22 miembros que fue incluido en el protocolo de diagnóstico genético recibió 2 sesiones de asesoramiento genético realizado por un grupo multidisciplinario y se firmaron consentimientos informados. A través de una encuesta se valoraron los aspectos psicológicos relacionados al asesoramiento genético. Se investigó la mutación presente mediante técnicas de inestabilidad microsatélite (utilizando 4 microsatélites: D3S1266, D2S123, D18S58 y D3S1266 y preestableciendo como inestabilidad microsatélite la presencia de 2 marcadores inestables) y determinando la expresión inmunohistoquímica del gen MLH1 con al anticuerpo clon G168-15. La mutación de dicho gen fue investigada en el ADN de linfocitos de los 22 individuos en estudio con técnicas de secuenciación automática y PCR. Estas técnicas fueron efectuadas en la Universidad de Creighton y Ohio. Todas las etapas de diagnóstico genético se realizaron en el marco de un equipo multidisciplinario (PROCANHE). Resultados: El total de afectados por cáncer fue de 12 (mediana de presentación: 47 años, rango: 26-74) siendo 9 de estos de ubicación colorrectal. El desarrollo de adenocarcinoma en esta ubicación en cinco casos fue antes de los 50 años... (TRUNCADO)

Differential expression of a virulence factor, the trans-sialidase, by the main Trypanosoma cruzi phylogenetic lineages.

The clinical outcome of Chagas disease is highly variable, mainly because of the heterogeneity of Trypanosoma cruzi, a parasite for which 2 major phylogenetic groups (I and II) were recently defined. Epidemiological and immunological data indicate that the prevalence of T. cruzi II in patients living in the southern cone of South America correlates with the alterations caused by Chagas disease. We report here that infection with T. cruzi II isolates induces 100% mortality in mice, in contrast to infection with T. cruzi I isolates, in which almost all mice enter the chronic phase even when a 1000-fold higher inoculum is administered. Trypomastigotes from T. cruzi II strains express and shed significantly higher amounts of trans-sialidase than do those from the T. cruzi I lineage. Disorganization of the thymus histoarchitecture associated with the circulating enzyme was observed after infection with T. cruzi II strains, in contrast to transient thymus lesions found in mice infected with T. cruzi I strains. Therefore, trans-sialidase becomes the first T. cruzi virulence factor identified that is differentially expressed by the main parasite groups and that contributes to their contrasting behaviors.

Incorporation of vancomycin-supplemented bone incorporation of vancomycin-supplemented bone allografts: radiographical, histopathological and immunohistochemical study in pigs.

We compared the incorporation of bone allografts with or without vancomycin in tibial defects of 18 pigs. High-quality radiographs, histological examination, immunological expression of metalloproteinase-13 (MMP-13) and transforming growth factor-beta 2 (TGFbeta2) indicated that there was no significant difference in bone allograft incorporation between up to 220 times the MIC (minimum inhibitory concentration) in bone allografts with 1 g of vancomycin in each 300 g of allograft or without this supplement.

Pathogenicity of the hereditary colorectal cancer mutation hMLH1 del616 linked to shortage of the functional protein.

BACKGROUND & AIMS: Hereditary nonpolyposis colorectal cancer is associated with mismatch repair deficiency. Most predisposing mutations prevent the production of functional mismatch repair protein. Thus, when the wild-type copy is also inactivated, the cell becomes mismatch repair deficient, and this leads to a high degree of microsatellite instability in tumors. However, tumors linked to nontruncating mutations may display positive or partly positive immunohistochemical staining of the mutated protein and low or atypical microsatellite instability status, which suggests impaired functional activity but not a total lack of mismatch repair. We found human mutL homology (hMLH) 1 del616, one of the most widespread recurring mutations in hereditary nonpolyposis colorectal cancer, segregating in a large hereditary nonpolyposis colorectal cancer family. Because the predicted coding change is a deletion of only 1 amino acid, the pathogenicity of the mutation was evaluated. METHODS: Many analyses were performed to assess the pathogenicity of hMLH1 del616 and to study the expression and function of the mutated messenger RNA and protein. RESULTS: Genetic and immunohistochemical evidence supported hMLH1-linked cancer predisposition in this family. Microsatellite instability varied from low to high, and the hMLH1 protein was lost in 2 tumors but was partly detectable in 1 tumor. Whereas similar optimal amounts of mutated hMLH1 del616 and wild-type hMLH1 proteins were equally functional in an in vitro mismatch repair assay, the amount of in vivo-expressed hMLH1 del616 was much lower than the amount of wild-type protein; this suggests that the deletion imparts instability to the mutant protein. CONCLUSIONS: Our results suggest that the pathogenicity of hMLH1 del616 is not linked to nonfunctionality, but to shortage of the functional protein.

Integracion donante-receptor del ligamento cruzado anterior en aloinjertos osteoarticulares: estudio histologico y molecular / Anterior cruciate ligament donor-receptor integration in osteoarticular allografts

Los objetivos del trabajo fueron determinar en un modelo porcino los aspectos biologicos y estructurales de la integracion del ligamento cruzado anterior enaloinjertos de femur distal y evaluar la incorporacion del ADN de los fibroblastos del receptor sobre el tejido donante (resumen truncado)

Integracion donante-receptor del ligamento cruzado anterior en aloinjertos osteoarticulares: estudio histologico y molecular / Anterior cruciate ligament donor-receptor integration in osteoarticular allografts

Los objetivos del trabajo fueron determinar en un modelo porcino los aspectos biologicos y estructurales de la integracion del ligamento cruzado anterior enaloinjertos de femur distal y evaluar la incorporacion del ADN de los fibroblastos del receptor sobre el tejido donante (resumen truncado)

Thymocyte depletion in Trypanosoma cruzi infection is mediated by trans-sialidase-induced apoptosis on nurse cells complex.

Trypanosoma cruzi, the causative agent of Chagas' disease, induces transient thymic aplasia early after infection-a phenomenon that still lacks a molecular explanation. The parasite sheds an enzyme known as trans-sialidase (TS), which is able to direct transfer-sialyl residues among macromolecules. Because cell-surface sialylation is known to play a central role in the immune system, we tested whether the bloodstream-borne TS is responsible for the thymic alterations recorded during infection. We found that recombinant TS administered to naive mice was able to induce cell-count reduction mediated by apoptosis, mimicking cell subsets distribution and histologic findings observed during the acute phase of the infection. Thymocytes taken after TS treatment showed low response to Con A, although full ability to respond to IL-2 or IL-2 plus Con A was conserved, which resembles findings from infected animals. Alterations were found to revert several days after TS treatment. The administration of TS-neutralizing Abs to T. cruzi-infected mice prevented thymus alterations. Results indicate that the primary target for the TS-induced apoptosis is the so-called "nurse cell complex". Therefore, we report here supporting evidence that TS is the virulence factor from T. cruzi responsible for the thymic alterations via apoptosis induction on the nurse cell complex, and that TS-neutralizing Abs elicitation during infection is associated with the reversion to thymic normal parameters.

Trypanosoma cruzi surface mucin TcMuc-e2 expressed on higher eukaryotic cells induces human T cell anergy, which is reversible.

Chagas' disease is a chronic, debilitating, multisystemic disorder that affects millions of people in Latin America. The protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas' disease, has a large number of O-glycosylated Thr/Ser/Pro-rich mucin molecules on its surface (TcMuc). These mucins are the main acceptors of sialic acid and have been suggested to play a role on various host-parasite interactions, such as adhesion to macrophages, protection from complement lysis, and immunomodulation of the immune response mounted by the host. To observe the immunologic effect obtained by the heterologous expression of a TcMuc gene in higher eukaryotic cells exposed to xenogeneic lymphocytes, we developed a strategy based on the transfection of a known T. cruzi mucin gene (TcMuc-e2) into Vero cells. In contrast to the brisk proliferation and activation of human lymphocytes observed at 3, 4, and 5 days induced by normal Vero cells, neither proliferation nor significant activation of human lymphocytes was observed with TcMuc-e2-transfected Vero cells. This TcMuc-e2 mucin-induced suppression of T cell response can be reversed by the addition of exogenous IL-2. In addition it was demonstrated that the immunosuppressive reaction was not related to the induction of an important degree of apoptosis in human lymphocytes. Posttranslational modification are required for the inhibitory effect that TcMuc-e2 exerts when transfected to Vero cells. O-glycosylation and sialylation are required to obtain the immunomodulatory effect as assessed by O-sialoglycoprotease and neuraminidase treatments. These results are consistent with other studies showing that surface glycoconjugates from T. cruzi and mammalian cells can induce an inhibition of the immune response.

Estudio de factores genético-moleculares del virus de la hepatitis C asociados a la actividad de telomerasa hepática en el hepatocarcinoma / Study of genetic-molecular factors of the hepatitis C virus associated to the hepatic telomerase activity in hepatocarcinoma

El virus de la hepatitis C (HCV) constituye en el mundo el agente etiológico asociado a la mayor incidencia de hepatitis crónica que puede conducir la cirrosis hepática y, eventualmente al hepatocarcinoma. Más de 300 millones de personas padecen infección crónica por este virus, representando una causa significativa de morbi-mortalidad, frente a la cual urgen medidas de control efectivas. Originalmente, la magnitud de la heterogeneidad genética del virus no fue claramente advertida. Sin embargo, esta característica irrumpió con sus inherentes implicancias en la patogenia, el diagnóstico, la terapéutica y la inmunoprofilaxis. En cada paciente infectado, el HCV circula como una población heterogénea de variantes virales genéticamente relacionadas que se denominan cuasiespecies. Las mismas se exhiben dinámicas en el curso de la infección cambiando en forma progresiva, alentando una estrategia capaz de evadir los mecanismos de inmunidad humoral y celular desarrollados por el hospedador, y consecuentemente, estableciendo una infección persistente. Existen múltiples evidencias que demuestran que la caracterización genómica de HCV es relevante desde el punto de vista clínico. Importantes diferencias han surgido respecto del curso natural y la severidad de la infección, la evolución post-transplante hepático, el diagnóstico molecular e inmunoserológico, la vía de infección y aún la eficacia de la terapéutica con interferón alfa. El desarrollo de herramientas terapéuticas y profilácticas capaces de limitar la infección por HCV, debe estar sustentado por minuciosos estudios que consideren la heterogeneidad genética exhibida por este agente. En diversas neoplasias -incluídos los hepatocarcinomas (HCC)- se ha documentado la actividad de la oncoenzima telomerasa. Esta ribonucleoproteína con actividad telómero. La hipótesis de la senescencia celular asume que el acortamiento progresivo del telómero de células somáticas de organismos multicelulares, genera una señal que las inhabilita para el ingreso a sucesivos ciclos celulares. De este modo, la pérdida del telómero está asociada in vivo con el envejecimiento de modo tal que con posterioridad a un cierto número de duplicaciones, la célula detendrá su división, entrando en senescencia. Diferencialmente, en las células inmortalizadas, hematopoyéticas y reproductivas, la longitud del telómero está estabilizada, por la actividad de la telomerasa...(TRUNCADO)(AU)

Estudio de factores genético-moleculares del virus de la hepatitis C asociados a la actividad de telomerasa hepática en el hepatocarcinoma / Study of genetic-molecular factors of the hepatitis C virus associated to the hepatic telomerase activity in hepatocarcinoma

El virus de la hepatitis C (HCV) constituye en el mundo el agente etiológico asociado a la mayor incidencia de hepatitis crónica que puede conducir la cirrosis hepática y, eventualmente al hepatocarcinoma. Más de 300 millones de personas padecen infección crónica por este virus, representando una causa significativa de morbi-mortalidad, frente a la cual urgen medidas de control efectivas. Originalmente, la magnitud de la heterogeneidad genética del virus no fue claramente advertida. Sin embargo, esta característica irrumpió con sus inherentes implicancias en la patogenia, el diagnóstico, la terapéutica y la inmunoprofilaxis. En cada paciente infectado, el HCV circula como una población heterogénea de variantes virales genéticamente relacionadas que se denominan cuasiespecies. Las mismas se exhiben dinámicas en el curso de la infección cambiando en forma progresiva, alentando una estrategia capaz de evadir los mecanismos de inmunidad humoral y celular desarrollados por el hospedador, y consecuentemente, estableciendo una infección persistente. Existen múltiples evidencias que demuestran que la caracterización genómica de HCV es relevante desde el punto de vista clínico. Importantes diferencias han surgido respecto del curso natural y la severidad de la infección, la evolución post-transplante hepático, el diagnóstico molecular e inmunoserológico, la vía de infección y aún la eficacia de la terapéutica con interferón alfa. El desarrollo de herramientas terapéuticas y profilácticas capaces de limitar la infección por HCV, debe estar sustentado por minuciosos estudios que consideren la heterogeneidad genética exhibida por este agente. En diversas neoplasias -incluídos los hepatocarcinomas (HCC)- se ha documentado la actividad de la oncoenzima telomerasa. Esta ribonucleoproteína con actividad telómero. La hipótesis de la senescencia celular asume que el acortamiento progresivo del telómero de células somáticas de organismos multicelulares, genera una señal que las inhabilita para el ingreso a sucesivos ciclos celulares. De este modo, la pérdida del telómero está asociada in vivo con el envejecimiento de modo tal que con posterioridad a un cierto número de duplicaciones, la célula detendrá su división, entrando en senescencia. Diferencialmente, en las células inmortalizadas, hematopoyéticas y reproductivas, la longitud del telómero está estabilizada, por la actividad de la telomerasa...(TRUNCADO)