The Role of the Immune System on the Cardiac Complications Observed in SARS-CoV-2

Abstract An acute respiratory syndrome caused by SARS-CoV2 was declared a pandemic by the World Health Organization. Current data in the world and in Brazil show that approximately 40% of patients who died have some type of cardiac comorbidity. There are also robust reports showing an increase in IL-6 / IL-1B / TNF-alpha and the presence of lymphopenia in patients with COVID-19. Our team and others have shown that increased cytokines are the link between arrhythmias/Left ventricular dysfunction and the immune system in different diseases. In addition, it has been well demonstrated that lymphopenia can not only be a good marker, but also a factor that causes heart failure. Thus, the present review focused on the role of the immune system upon the cardiac alterations observed in the SARS-CoV2 infection. Additionally, it was well described that SARS-CoV-2 is able to infect cardiac cells. Therefore, here it will be reviewed in deep.

Antibodies against Apicomplexa protozoa and absence sarcocysts in heart tissues from horses in southern Brazil / Anticorpos contra protozoários do filo Apicomplexa e ausência de sarcocistos no miocárdio de equinos no sul do Brasil

Abstract Sarcocystis spp., Neospora spp., and Toxoplasma gondii are Apicomplexa protozoa that can infect horses. This study aimed to investigate the occurrence of antibodies against Sarcocystis spp., Neospora spp., and T. gondii in horses slaughtered in southern Brazil. The presence of histological lesions, tissue cysts, and Sarcocystis spp. DNA in the hearts of these horses was also investigated. A total of 197 paired serum and heart samples were evaluated by serology and direct microscopic examination; 50 of these samples were subjected to histopathological and PCR analyses. Antibodies against at least one of the protozoa were detected in 146 (74.1%) of the serum samples. The frequencies of positive serology were: 36% (71/197) against Sarcocystis spp., 39.1% (77/197) against Neospora spp., and 47.2% (93/197) against T. gondii. No cysts, Sarcocystis spp. DNA, or histopathological lesions were observed in myocardial tissue samples. The frequencies of antibody seropositivity against Sarcocystis spp., Neospora spp., and T. gondii showed that horses are frequently infected by these parasites in southern Brazil. The absence of sarcocysts in horse tissues is compatible with their role as aberrant/accidental hosts in the life cycle of Sarcocystis spp..

Resumo Sarcocystis spp., Neospora spp. e Toxoplasma gondii são protozoários que pertencem ao filo Apicomplexa e que podem afetar equinos. O objetivo deste estudo foi investigar a ocorrência de anticorpos contra Sarcocystis spp., Neospora spp. e T. gondii. A presença de lesões histológicas, cistos teciduais e DNA de Sarcocystis spp. no miocárdio de equinos abatidos no sul do Brasil também foi investigado. Um total de 197 amostras de soro juntamente com as respectivas amostras de coração, foram avaliadas por sorologia e exame microscópico direto. Destas amostras, 50 foram selecionadas e submetidas a análise histopatológica e PCR. Anticorpos contra pelo menos um dos protozoários foi detectado em 146 (74,1%) das amostras de soro. As frequências de sorologia positiva foram: 36% (71/197) para Sarcocystis spp., 39,1% (77/197) para Neospora spp. e 47,2% (93/197) para T. gondii. Não foram encontradas lesões histopatológicas, cistos e DNA de Sarcocystis spp. nas amostras de miocárdio dos equinos. As frequências de soropositividade para Sarcocystis spp., Neospora spp. e T. gondii mostra que os equinos podem ser frequentemente infectados por estes parasitas no sul do Brasil. A ausência de sarcocistose no coração dos equinos é compatível com seu papel como hospedeiro errático/acidental no ciclo de vida deste protozoário.

Regulation of Cardiac β3-Adrenergic Receptors in Hyperglycemia.

Beta-adrenoceptors (β-AR), members of the G protein-coupled receptors play important roles in the regulation of heart function. A positive inotropic action of catecholamines is mediated through their interaction with β-AR, located on the sarcolemma, while they can also mediate some deleterious effects, such as cardiac arrhythmias or myocardial apoptosis. The well-known β-AR-associated signaling in heart is composed of a coupled mechanism among both β1- and β2-AR and stimulatory G protein (Gs). This coupled mechanism further leads to the activation of adenylyl cyclase and thereby increases in intracellular cAMP level. However, recent studies have emphasized the contribution of constitutive β3-AR coupling to Gi proteins, thereby initiating additional signal transduction pathways, particularly under physiopathological conditions. Diabetic cardiomyopathy, as a distinct entity is recognized due to its diminished responsiveness to β1-AR agonist stimulation in the heart from diabetic rats with no important changes in the responses mediated with β2-AR. Furthermore, an upregulation of β3-AR has been shown in diabetic rat heart with a strong negative inotropic effect on left ventricular function. Experimental data provide evidences that the mechanisms for the negative inotropic effect with β3-AR activation appear to involve a pertussis toxin (PTX)-sensitive G protein and the activation of a nitric oxide synthase pathway. On the other hand, β-blockers demonstrate marked beneficial effects in heart dysfunction with scavenging free radicals and/or acting as an antioxidant with both sex- and dose-dependent manner. However, further investigations are needed to clarify the roles of both altered expression and/or responsiveness of β-AR and the benefits with β-blocker treatment in diabetes. This review discusses the role of β-AR activation, particularly β3-AR in cardiac pathological remodeling under hyperglycemia.

Signaling Mechanisms Regulating Fibroblast Activation, Phenoconversion and Fibrosis in the Heart.

Cardiac fibroblasts (CFs) maintain the cardiac extracellular matrix (ECM) through myocardial remodelling. The remodelling process can become dysregulated during various forms of heart disease  which leads to an overall accumulation of ECM. This results in cardiac fibrosis which increases the risk of heart failure in many patients. During heart disease, quiescent CFs undergo phenoconversion to an activated cell type called cardiac myofibroblasts (CMFs). Factors influencing phenoconversion include transforming growth factor β (TGF-β) which via SMADs (small mothers against decapentaplegic) activates the myofibroblast marker gene αSMA (α smooth muscle actin). Signaling molecules as diverse as NAD(P)H oxidase 4 (Nox4) and Wnt have been found to interact with TGF-β signalling via SMADs. Pathways, including FAK/TAK/JNK and PI3K/Akt/rac have also been implicated in activating phenoconversion of fibroblasts. Another major contributor is mechanical stress exerted on CFs by ECM changes, which involves activation of ERK and subsequent αSMA expression. Other factors, such as the mast cell protease tryptase and the seeding density also affect the phenoconversion of fibroblast cultures in vitro. Further, reversal of myofibroblast phenotype has been reported by a negative regulator of TGF-β, Ski, as well as the hormone relaxin and the second messenger cAMP. Targeting the signaling molecules involved in promoting phenoconversion of CFs to CMFs presents a possible method of controlling cardiac fibrosis. Here, we provide a brief review of signaling mechanisms responsible for phenoconversion and identify critical targets for the treatment of cardiac fibrosis.

Detección de antígenos del virus del dengue en tejidos post mórtem / Detection of dengue virus antigen in post-mortem tissues

El panorama epidemiológico del dengue ha empeorado durante la última década. Las dificultades para prevenir su transmisión, así como la ausencia de una vacuna o tratamiento específico, lo convierten en un riesgo que desafía las medidas de salud pública y desborda la capacidad de los centros de salud y los sistemas de investigación a muchos niveles. Actualmente, la mayoría de los estudios sobre la patogenia de la infección centran su atención en la respuesta inmunitaria de las células T casi exclusivamente en infecciones secundarias y están dirigidos a identificar los mecanismos implicados en el desarrollo de la permeabilidad vascular y de los eventos hemorrágicos que lo acompañan. En este reporte se describe el caso de una menor de 45 días de edad con signos clínicos de dengue grave, cuyo diagnóstico se confirmó por reacción en cadena de la polimerasa de transcripción inversa en muestras de tejido post mórtem y por herramientas de apoyo diagnóstico de inmunohistoquímica, las cuales detectaron antígenos virales en todos los órganos obtenidos en la necropsia. Este caso subraya la importancia del estudio de las infecciones primarias asociadas a dengue grave, particularmente en niños, en quienes es más probable el desarrollo de la forma grave de la enfermedad sin una infección previa, y, además, pone de relieve la importancia de un diagnóstico que no se limite a las muestras de tejido hepático en el estudio de la patogenia de la infección viral.

The epidemiological situation of dengue has worsened over the last decade. The difficulties in preventing its transmission and the absence of a vaccine or specific treatment have made dengue a serious risk to public health, health centers and research systems at different levels. Currently, most studies on the pathogenesis of dengue infection focus on the T-cell immune response almost exclusively in secondary infections and are aimed at identifying the mechanisms involved in the development of vascular permeability and bleeding events that accompany the infection. This report describes the case of a baby girl less than 45 days of age with clinical signs of severe dengue, whose diagnosis was confirmed by reverse transcription polymerase chain reaction in post-mortem tissue samples and by the ancillary diagnostic use of immunohistochemistry, which detected viral antigens in all organs obtained at autopsy. This case highlights the importance of studying primary infections associated with severe dengue, particularly in children, who are more likely to develop the severe form of the disease without previous infection, and it further stresses the importance of a diagnosis that should not be based solely on the examination of liver tissue samples when studying the pathogenesis of the viral infection.

The TcI and TcII Trypanosoma cruzi experimental infections induce distinct immune responses and cardiac fibrosis in dogs

Trypanosoma cruzi infection may be caused by different strains with distinct discrete typing units (DTUs) that can result in variable clinical forms of chronic Chagas disease. The present study evaluates the immune response and cardiac lesions in dogs experimentally infected with different T. cruzi strains with distinct DTUs, namely, the Colombian (Col) and Y strains of TcI and TcII DTU, respectively. During infection with the Col strain, increased levels of alanine aminotransferase, erythrocytes, haematocrit and haemoglobin were observed. In addition, CD8+ T-lymphocytes isolated from the peripheral blood produced higher levels of interleukin (IL)-4. The latter suggests that during the acute phase, infection with the Col strain may remain unnoticed by circulating mononuclear cells. In the chronic phase, a significant increase in the number of inflammatory cells was detected in the right atrium. Conversely, infection with the Y strain led to leucopoenia, thrombopoenia, inversion of the ratio of CD4+/CD8+ T-lymphocytes and alterations in monocyte number. The Y strain stimulated the production of interferon-γ by CD4+ and CD8+ T-lymphocytes and IL-4 by CD8+ T-cells. In the chronic phase, significant heart inflammation and fibrosis were observed, demonstrating that strains of different DTUs interact differently with the host.

Trypanosoma cruzi: parasite antigens sequestered in heart interstitial dendritic cells are related to persisting myocarditis in benznidazole-treated mice

We investigated whether sequestered Trypanosoma cruzi antigens found in heart interstitial dendritic cells (IDCs) contribute to the residual myocarditis found in mice following treatment with benznidazole, a specific chemotherapeutic drug. IDCs are antigen-presenting cells that are MHC-II-receptor dependent. Swiss mice were divided into two experimental groups: the 1st group was infected with the Colombian strain of T. cruzi, which is resistant to treatment with benznidazole, and the 2nd group was infected with clone 21SF-C 3, which has a medium susceptibility to the drug. Treatment of the Colombian strain group started on the 120th day post-infection and for the 21SF-C3 strain group treatment was started on the 90th day. In both groups, treatment lasted for 90 days. The animals were sacrificed either 150 or 200 days post-treatment. The myocardium was analysed by immunohistochemistry using anti-MAC3, 33D1, CD11b and CD11c monoclonal antibodies for IDCs or anti-T. cruzi purified antibodies. Parasite antigens were expressed on the IDC membranes in both treated and untreated mice. Myocarditis subsided following treatment, evidenced by both histological and morphometrical evaluation. A reduction in the number of IDCs carrying T. cruzi antigens in the treated group indicates that the elimination of parasites influences antigen presentation with concomitant decreases in inflammation. There is a correlation between the presence of T. cruzi antigens in these cells and the chronic focal, residual myocarditis seen in treated mice.

Producción de interferón gamma por linfocitos pas-positivos infiltrados en corazones de pacientes chagasicos en los sitos de lesiones / Interferon gamma production by pas-positive T Lymphocytes of chagastic patients infiltrated into human hearts in the sites of lesions

En sangre de chagásicos en trabajos previos se halló un número alto de linfocitos T productores de substancia P.A.S.- positiva, más numerosos en chagásicos con electrocardiograma anormal. Luego los hallamos infiltrados en el corazón chagásico. En este trabajo consideramos nuestra hipótesis de que esa substancia linfocitaria sería Interferongamma. Material y Métodos. Muestras de corazones de 8 chagásicos fallecidos por muerte cardiaca. Se utilizaron anticuerpos monoclonales anti-IFN gamma humano; para linfocitos T activados (CD45 ROJ, y la reacción del P.A.S, respectivamente. Las células positivas se contaron en 50 campos a 400x y el estado de miocardio se comparó con datos clínicos. También. en frotis de sangre de pacientes chagásicos con ECG anormal, investigamos inmunomarcación con anti interferon gamma y la P.A.S.-positividad, respectivamente. Resultados El mayor número de células infiltrantes intracardiacas (65-75%) resultaron positivos para IFN gamma, y similares valores para P.A.S.-positividad y para CD45 RO. En sangre hallamos 41 % ±7 de linfocitos P.A.S.-positivos: y similar de positivos para IFN-gamma. Conclusiones: Los datos muestran que los linfocitos P.A.S.-positivos de los chagásicos producen IFN-gamma tanto en sangre. Como infiltrados en tejidos cardíacos. e indican una fuerte respuesta T-helper l. También explican la gran afluencia de macrófagos en dichos tejidos cardíacos. No se vieron parásitos T. cruzi ni formas intracelulares. Esos hechos refuerzan los datos que indican existencia de autoinmunidad en Chagas. Abrimos una pregunta: ¿a que antígeno/s responden en el corazón chagásico los linfocitos T P.A.S.-positivos productores de IFN-gamma?

In the blood of chagasic patients, a high number of T-lymphocytes producers of a P.A.S.-positive substance was found, more numerous in chagasics with abnormal electrocardiogram. Further. We found such lymphocytes infiltrated in the chagasic heart. Here, we considered our hypothesis that those lymphocytes would be Interferon -gamma producer' cells. Material and Methods: Heart samples of 8 patients deceased due to chagasic heart disease (ChHD). Cuts of 5 microns were submitted to monoclonal antibodies for human Interferon-gamma; to CD45RO for activated T lymphocytes; and to the classical Periodic acid Schiff reaction (P.A.S.), respectively. In blood smears from chagasic patients with ChHD, the reactivity for anti Interferon gamma and for the P.A.S. reaction was compared, regarding the respective positive cell number. The myocardium status was compared with clinical date. Results: In hearts, 65-75% of infiltrated lymphocytes were positive for IFN-gamma; similar values were found, in seriated cuts, of P.A.S.-positive lymphocytes, as well as of CD45RO+. In blood, there were 41 % ±9 of P.A.S.positive lymphocytes, similar to positive cells for IFN-gamma. Conclusions: The data indicates that the P.A.S.-positive lymphocytes from chagasic patients are producers of IFN gamma in blood, as well as when infiltrated into the cardiac tissues. Such fact explains also the great affluence of macrophages in cardiac tissues in ChHD. The data indicate a strong response of T helper 1 type in this severe advanced stage of Chagas'disease. Either Trypanosome cruzi parasites or intracellular forms were seen in these hearts. This favours the data showing autoimmune mechanisms in this process. We open a question: to which antigen/s respond in the chagasic hearts the lymphocytes producers of IFN gamma?

Myocardial injury occurs earlier than myocardial inflammation in acute experimental viral myocarditis

Endomyocardial biopsy often fails to show myocardial inflammation for patients with clinically suspected myocarditis. The serum isoforms of troponin T (cTnT) level is a very sensitive marker of myocardial injury and it is elevated even in the absence of myocardial inflammation. We investigated the correlations for myocardial injury, virus titers and inflammation in acute viral infection. Using the murine coxsackievirus group B3 (CVB3) myocarditis model, the histopathologic findings and virus titers in mouse hearts were compared with the serum cTnT levels measured by ELISA at various time points. Viable virus titers in the hearts peaked at 3 days after infection (8.22+/-0.13 log10 PFU/100 mg of heart); they decreased at day 7 and no viable virus was detected from day 14. Myocardial inflammation was minimal at day 3, peaked at day 7 and markedly decreased at day 14. The individual serum TnT levels were significantly increased at day 3 (7.37+/-1.46 ng/ml), persisted to day 7 (0.73+/-0.08 ng/ml), and normalized at day 14. Serum cTnT levels were correlatable with virus titers in the heart (r=0.744, P <0.01), but the serum cTnT levels were not correlated with the degrees of inflammation. Using the less myocarditic strain of CVB3, similar relationships were observed between the changes for the serum cTnT levels and the heart virus titers. During the course of viral infection, myocardial injury precedes the pathologic evidence of inflammation, and the elevated cTnT levels provide evidence of myocardial injury even in the absence of any histologic findings of myocarditis.

Efecto de gangliosidos in vitro sobre linfocitos de pacientes chagasicos estimulados con mitogenos o con antigenos de corazón o cerebro / Gangliosides in vitro effects on lymphocytes from patients with chronic Chagas disease stimulated with mitogens or heart or brain antigens

Se estudió in vitro el efecto de gangliósidos sobre las respuestas de linfocitos de pacientes chagásicos estimulados con mitógenos o con antígenos de corazón y cerebro. La razón para efectuar este estudio fueron las evidencias que indican un rol de los linfocitos T en la producción de daños de la cardiopatía chagásica, y datos que indican que los gangliósidos pueden tener actividad sobre esas células. Además, en trabajos previos, hallamos que los linfocitos de chagásicos responden con transformación blástica (TB). Material y Métodos: se efectuaron cultivos de leucocitos de 14 pacientes chagásicos. A los cuales se adicionaron gangliósidos y en esas condiciones, se estimularon con mitógenos, o bien con antígenos de corazón humano o cerebro murino, respectivamente. Resultados: se observó inhibición parcial de la transformación blástica Inducida por mitógenos, y también hubo Inhibición parcial de la TB inducible por los antígenos de corazón o de cerebro en los linfocitos de chagásicos, siendo significativas las diferencias con respecto a los controles (p< 0.001). Conclusiones: se considera de Interés ese efecto inhibidor de gangliósidos sobre las actividades de los linfocitos de chagásicos estudiadas en estos experimentos, por ser directamente vinculables a factores de patogenia chagásica, que podrían ser Inmunomodulados.

In human Chagas'disease previous work has shown the occurrence of a T-lymphocyte CD4-positive population (a high producer of PAS-positive glycoproteins) with evidence suggesting a role in the formation of damages to the myocardium and neural structures in chagasic heart disease (ChHD). Other workers have taken such facts into consideration and have employed gangliosides (biological substances with neurotrophic and immunomodulatory properties) in chagasics with chronic cardiomyopathy and disautonomic signs, obtaining an Improvement in functional signs and a decrease in the number of PAS+ lymphocytes. In the present work we have studied the effect of mixed gangliosides (Cronassial on cell cultures of total leukocytes, or on mononuclear cells prepared through Ficoll-Hypaque. Blood was obtained from 14 patients with ChHD. Experiments were undertaken to assess the effect of policlonal mitogens Phytohaemagglutinin (Phy) and Concanavalin A (Con A) on blastic transformation, estimated by cell size and cytologic study. In addition, the production of PAS+ substances by the lymphocytes and blast were assessed. Gangliosides were added at final concentrations of 100 mg/ml or 200 mg/ ml. Cell viability was assessed by means of the Trypan blue test. With respect to blastic transformation, results showed a significant decrease in the cultures that received gangliosides 24 hours before mltogen administration, as compared with controls (p<0.001) (both for Phy and Con A). On the other hand, the production of lymphocytic PAS+ substances decreased in the cultures of chagasics in which gangliosides were added. Some of these results confirmed previous findings on the matter. The facts suggest that gangliosides can modulate some lymphocytic activities in chagasics.

Detecçäo de anticorpo anticoraçäo em camundongos Balb/c imunizados com Streptococcus mutans / Detection of heart-reactive antibody in Balb/c mice immunized with Streptococcus mutans

Anticorpos para antígenos cardíacos foram analisados por ELISA em 14 soros de camundongos Balb/c hiperimunizados com Streptococcus mutans, inativado pelo formaldéido. Os níveis de anticorpos da classe IgG anticoraçäo e antimiosina elevaram-se significativamente nos animais imunizados quando comparados com os controles, especialmente no grupo A, imunizado e reestimulado com antígenos solúveis de S. mutans. Neste grupo, os resultados do "Western Blot" mostraram reatividade com miosina cardíaca e uma banda de 35 kDa. A análise histológica dos coraçöes dos animais do grupo B, imunizado e reestimulado com antígenos de superfície do microrganismo, demonstrou a presença de degeneraçäo celular, tipo hidrópica e hialina e focos inflamatórios constituídos de linfócitos e macrófagos no miocárdio e pericárdio. Os resultados deste trabalho reforçam a hipótese da existência de mimetismo antigênico entre tecido cardíaco e S. mutans e chamam a atençäo para o risco de desenvolvimento de anticorpos reativos com antígenos próprios induzidos por vacina anticárie com componentes estreptocócicos

Immunocytochemical reaction of sera from chagasic patients against trypanosoma cruzi, intestine of triatoma infestans and normal human heart

Chagas disease has been considered by some authors as an autoimmune pathology and denied by others. In this paper we present by means of immunocytochemical reactions with sera of chagasic patients, evidence in favor of the presence of similar antigens in the parasite, vector and non chagasic human heart. The immunocytochemical technique used permits the localization by electron microscopy of the antigens in the peritrophic membrane of the parasite and basement membranes of the vectorïs midgut and of the myosin band of the normal human heart. These observations support the assumption of an autoimmune response in Chagas disease.

Effect of angiopeptin and aspirin on accelerated graft atherosclerosis in transplanted mouse heart

In this study of the inhibitory effects of angiopeptin and aspirin on the development of accelerated graft atherosclerosis (AGAS), 22 B10.BR mice received intra-abdominal heterotopic heart transplants from B10.A mice, without immunosuppression. Group 1 (n = 5) received no pharmacological intervention, Group 2 (n = 6) was treated with angiopeptin, Group 3 (n = 5) with aspirin, and Group 4 (n = 6) with both. There was no significant difference in the incidence of AGAS among these groups. The magnitude of intimal lesion development showed less narrowing of large vessels (> 100 microns in diameter) in groups 2 and 4--i.e. the groups received angiopeptin (Group 1 = 46.9 +/- 9.3%, Group 2 = 28.5 +/- 9.2%, Group 3 = 44.1 +/- 10.9%, Group 4 = 24.2 +/- 5.9%; p < 0.01). Comparison of the fraction of tropomyosin-positive staining cells in the intima revealed a lesser degree of staining in Group 2 (p < 0.01). No intervention was effective in preventing smooth muscle cell proliferation in the media or inflammatory cell infiltration in the adventitia. In conclusion, our data suggest that angiopeptin is effective in the direct inhibition of intimal smooth muscle cell proliferation in relatively large vessels, whereas aspirin exhibits no inhibitory role in the progression of AGAS. Angiopeptin appears to be a potential therapeutic agent for inhibiting the progression of postoperative AGAS in clinical heart transplantation.

Interleucinas 1ß, 6 y 10 en homogeneizados de corazón y de pulmón postperfusión y reperfusión del bloque cardiopulmonar / Interleukines 1ß, 6 and 10 in heart and lung homogenates postperfusion and reperfusion of the cardiopulmonary block

Introducción: Como consecuencia de la perfusión y de la reperfusión de órganos existe daño tisular. La síntesis y la liberación de citocinas se afectan como respuesta al daño celular. Objetivo: En este trabajo, evaluamos los cambios que ocurren en la concentración de interleucinas 1ß, 6 y 10 en homogeneizados de corazón y de pulmón como respuesta al daño ocasionado por el efecto de la perfusión y de la reperfusión cardiopulmonar. Material y métodos: utilizamos los bloqueos cardiopulmonares de 21 ratones Balb-C, estos bloques fueron divididos al azar en tres grupos de estudio (n= 7 en cada grupo). Grupo 1: Los bloques fueron perfundidos in situ a través de la arteria pulmonar con solución de Krebs-Henseleit a 4 ºC con un flujo de perfusión de 0.2 mL/min únicamente durante el tiempo necesario para exanguinarlos. Grupo 2: los bloques fueron perfundidos in situ durante 30' a través de la arteria pulmonar con solución de Krebs-Henseleit a 4 ºC con un flujo de perfusión de 0.2 mL/min. Grupo 3: los bloques fueron exanguinados mediante perfusión in situ a través de la arteria pulmonar con solución de Krebs-Henseleit a 4 ºC con un flujo de perfusión de 0.2 mL/min, se preservaron durante 24 horas a 4 ºC sumergidos en la misma solución a transcurrido el tiempo de isquemia, fueron reperfundidos ex vivo durante 30' con solución de Krebs-Henseleit a ºC con un flujo de perfusión de 0.2 mL/min. Concluidas las perfusiones y las reperfusiones preparamos homogeneizados de corazón y de pulmón. Determinamos la concentración de las interleucinas presentes en cada homogeneizado tisular mediante la técnica de ELISA. Resultados. La concentración de IL-6 fue similar en los homogeneizados de corazón y de pulmón y no se alteró por efecto de la reperfusión, mientras que las concentraciones de IL-1ß e IL-10 parecen actuar de manera inversa entre ambos órganos y durante todo el estudio

Fenotipo y reactividad de linfocitos T aislados de la placa ateromatosa. Enseñanzas de un trasplante / Phenotype and reactivity of T lymphocytes isolated from atheromatous plaque. Knowledge derived from a heart transplant case

La hipótesis de la reacción inmmunológica primaria reconoce que el daño inicial en la formación de la placa ateromatosa está mediado por linfocitos T reactivos dirigidos contra proteínas de choque térmico, lipoproteínas, bacterias, virus o antígenos del sistema principal de histocompatibilidad del donador. Una causa frecuente de falla de trasplante cardiaco es la formación de lesiones ateromatosas en los vasos arteriales del órgano trasplantado a pesar de la ausencia de dichas lesiones en el donador, lo cual sugiere que las lesiones obstructivas de novo son consecuencia de una respuesta inmune celular por parte del receptor. En este estudio determinamos el fenotipo y la reactividad de linfocitos T aislados de sangre periférica y de biopsias de endomiocardio y aterectomía de un paciente vivo e inmunosuprimido, sometido a trasplante cardiaco en 1989. Los linfocitos del paciente fueron enfrentados a un grupo de linfocitos B transformados por EBV con diferences alelos HLA. Los resultados demostraron un incremento notable en el porcentaje de linfoncitos CD4+ en la placa ateromatosa y en el endocardio, una importante cantidad de linfocitos T TCRd+ en la placa, y una considerable pérdida de alorreactividad a diferentes antígenos HLA. Estos re sultados sugieren que a pesar de que existen poblaciones linfocíticas adecuadas para generar una respuesta celular, existe un estado de energia a los antígenos HLA, que pudiera ser secundario al prolongado tratamiento inmunosupresor. Creemos que las lesiones obstructivas en este paciente no responden a alorreactividad a los antígenos HLA, sino más bien a un cambio en el tipo de respuesta inmune celular como consecuencia a una exposición crónica a algún antígeno del donador, explicando así la elevada proporción de linfocitos T TCRd+

Autoimmunity in Chagas' heart disease

The time scale dissociation between high parasitemia and tissue pathology allied to the absence of parasites in the heart lesions of chronic Chagas' disease cardiopathy, casted doubt on the direct participation of Trypanosoma cruzi in tissue lesions. Moreover, the heart tissue lesions in chronic Chagas' disease cardiopathy are associated to an inflammatory mononuclear cell infiltrate, presumably the ultimate effectors of tissue damage. It has been hypothesized that the inflammatory cell infiltrate could mediate a delayed hypersensitivity process directed to the heart tissue components, an autoimmune response triggered by immunological cross-reactivity in the course of a protective immune response against some T. cruzi antigen homologous to heart proteins. However, little is known about the efector role of the T cells in the infiltrate, or about the nature of the antigen that lead to their accumulation in tissue. In this paper, we will review the published evidence on autoimmunity and immunological cross-reactivity between T cruzi and the mammalian host, along with data generated in our laboratory. The definition of the precise role played by autoimmunity in the pathogenesis of Chagas' disease cardiopathy may have important consequences both for immunoprophylaxis and for the therapeutic approach of chronic Chagas' disease.

Experimental autoimmune myocarditis: a suitable model to study neuroimmune crosstalk

This review regards the main functional characteristics of hearts subjected to an autoimmune response focusinf especially on the role of T lymphocytes and autoantibodies in the development of cardiac dysfunction. Evidence of a strong association in the onset and time-course of immune response and cardiac dysfunction is presented and the results are viewed comparatively with myocarditis models induced by heart, parasite or virus inoculation. Cardiac damage is evaluated regarding various aspects, namely histologic, immunologic, biochemical, pharmacologic, physiologic. Finally, the model, for its characteristics of resulting from an autoimmune response against the heart with functional consequences, has proved its usefulness to study neuroimmune interaction, mainly the immune to nervous direction, as autoantibodies and T cell-derived factors have a role in cardiac failure.