The Role of Platelets in Malarial Acute Lung Injury and Acute Respiratory Distress Syndrome: A World of Possibilities.

In recent decades our understanding of platelets’ role in immune response has increased. Traditionally platelets were considered as bleeding-stopping and thrombosis-causing cells. In recent years the platelets’ role in malarial innate and adaptive immune responses is being recognized. Platelets play critical role in pathogenesis of malaria infection leading to variety of outcomes. It is being realized that platelets play dual role in case of malaria (i) by preventing early stage exponential growth of parasitemia (ii) promoting exaggerated immune responses later. Platelets role in pathogenesis of severe and cerebral malaria has been widely studied. However their role in malaria related acute lung injury and respiratory distress has gained less attention. Recently the presence of active megakaryocytes and proplatelets have been explained in human lungs. Simultaneously, the platelets role in pathogenesis of acute lung injury and respiratory distress (ALI/ARDS) was also recognized. This gives a hint that there is a possible association of platelets with malaria related respiratory diseases as well. ALI/ARDS are characterized by lung edema due to increased permeability of the alveolar-capillary barrier and subsequent impairment of arterial oxygenation. In this review we have attempted to establish the importance of role of platelets in malaria related acute lungs injury and malaria acute respiratory distress syndrome and try to explain the underlying mechanism of this process. In ALI/ARDS, including those caused by malaria, platelets participate sequestration to the vascular bundle facilitating the recruitment of immune cells viz. neutrophils. Additionally, they secrete or induce the secretion of chemokines that result into vascular damage.

Nonhomogeneous immunostaining of hyaline membranes in different manifestations of diffuse alveolar damage / Imunomarcação não homogênea das membranas hialinas na sindrome da angustia respiratório do adulto pulmonar, extrapulmonar e idiopática

PURPOSE: To determine the nature of hyaline membranes in different manifestations of diffuse alveolar damage, [pulmonary and extrapulmonary acute respiratory distress syndrome], and idiopathic [acute interstitial pneumonia]. MATERIALS AND METHODS: Pulmonary specimens were obtained from 17 patients with acute respiratory distress syndrome and 9 patients with acute interstitial pneumonia. They were separated into 3 different groups: (a) pulmonary diffuse alveolar damage (pDAD) (n = 8), consisting only of pneumonia cases; (b) extrapulmonary diffuse alveolar damage (expDAI) (n = 9), consisting of sepsis and septic shock cases; and (c) idiopathic diffuse alveolar damage (iDAD) (n = 9), consisting of idiopathic cases (acute interstitial pneumonia). Hyaline membranes, the hallmark of the diffuse alveolar damage histological pattern, were examined using various kinds of antibodies. The antibodies used were against surfactant apoprotein-A (SP-A), cytokeratin 7 (CK7), cytokeratin 8 (CK8), alpha smooth muscle actin (a-SMA), cytokeratin AE1/AE3 (AE1/AE3), and factor VIII-related antigen (factor VIII). RESULTS: Pulmonary diffuse alveolar damage showed the largest quantity of hyaline membranes (12.65 percent ± 3.24 percent), while extrapulmonary diffuse alveolar damage (9.52 percent ± 3.64 percent) and idiopathic diffuse alveolar damage (7.34 percent ± 2.11 percent) showed intermediate and lower amounts, respectively, with the difference being statistically significant between pulmonary and idiopathic diffuse alveolar damage (P < 0.05). No significant difference was found for hyaline membranes Sp-A immunostaining among pulmonary (15.36 percent ± 3.12 percent), extrapulmonary (16.12 percent ± 4.58 percent), and idiopathic (13.74 ± 4.20 percent) diffuse alveolar damage groups. Regarding factor VIII, we found that idiopathic diffuse alveolar damage presented larger amounts of immunostained hyaline membranes (14.12 percent ± 6.25 percent) than extrapulmonary diffuse alveolar damage...

OBJETIVO: Determinar a natureza da membrana hialina nas diferentes manifestações do dano alveolar difuso [pulmonar e extrapulmonar síndrome do desconforto respiratório] e idiopático [pneumonia intersticial aguda]. MATERIAIS E MÉTODOS: Espécimes pulmonares foram obtidos de 17 pacientes com SDRA e 9 pacientes com pneumonia intersticial aguda e separados em três diferentes grupos: (a) dano alveolar difuso pulmonar (DADp) (n=8) constituído por casos de pneumonia, (b) dano alveolar difuso extrapulmonar (DADexp) (n=9) constituído por casos de sepse e choque séptico e (c) dano alveolar difuso idiopático (DADi) (n=9) constituído por casos idopáticos (ou pneumonia intersticial aguda). As características das membranas hialinas do padrão histológico de dano alveolar difuso foram examinadas usando vários tipos de anticorpos. Os anticorpos usados foram surfactante apoproteina A (SP-A), anti-citokeratina 7 (CK7), citokeratina 8 (CK8), alfa actina de músculo liso (a-SMA), citokeratina AE1/AE3 (AE1/AE3) e antígeno relacionado ao fator VIII (Fator VIII). RESULTADOS: Observaram-se aumentos maiores da quantidade de membrana hialina no dano alveolar difuso pulmonar (12.65 ± 3.24 por cento), intermediários no dano alveolar difuso extrapulmonar (9.52 ± 3.64 por cento) e baixos no dano alveolar difuso idiopático (7.34 ± 2.11 por cento) respectivamente, esta diferencia foi estatística significante entre o dano alveolar difuso pulmonar e o dano alveolar difuso idiopático (p<0.05). Não se encontrou significância estatística para a quantidade de imunomarcação de Sp-A nos grupos de dano alveolar difuso pulmonar (15.36 ± 3.12 por cento), extrapulmonar (16.12 ± 4.58 por cento) e idiopático (13.74 ± 4.20 por cento). Com relação ao Fator VIII, nós encontramos maiores aumentos da imunomarcação da membrana hialina no grupo dano alveolar difuso idiopático (14.12 ± 6.25 por cento) do que no dano alveolar difuso extrapulmonar (3.93 ± 2.86 por cento), com significância estatística (p<0.001). Da mesma...

Patogénesis molecular del distrés / Molecular pathogenesis of distress

Estudios clínicos avanzados proponen y prueban múltiples terapéuticas inmunológicas, dirigidas a interferir con los complejos sistemas mediadores de la respuesta inflamatoria; otra razón de los clínicos para un conocimiento profundo de la patogénesis del síndrome de distrés respiratorio del adulto. Se revisó bibliografía internacional actualizada, publicada en revistas y libros de texto. Se seleccionó información de 26 de los artículos cuyas fechas de publicación oscilan entre los años 1989 y 1925. Esta información se utilizó para hacer énfasis en la fisiopatología molecular de la respuesta inflamatoria, así como, en la interrelación de sus distintos componentes entre sí y con el daño orgánico pulmonar y difuso