Joziana Muniz de Paiva Barçante

Cytological and parasitological analysis of bronchoalveolar lavage fluid for the diagnosis of Angiostrongylus vasorum infection in dogs

Bronchoalveolar lavage (BAL) is a procedure that retrieves cells and other elements from the lungs for evaluation, which helps in the diagnosis of many pulmonary diseases. The aims of this work were to perform this procedure in dogs in the acute and chronic phases of an Angiostrongylus vasorum infection for cytological analysis and to evaluate the potential of this technique as a diagnostic method for this lung-heart worm. The BAL procedure was performed through the use of an endotracheal tube on seven A. vasorum infected dogs and on five non-infected dogs lined as a control group. Sixty days post-infection (dpi) active and live larvae were retrieved from the bronchoalveolar fluid (BALF) of all infected dogs. Furthermore, in one animal it was possible to retrieve larvae in its BALF before the pre-patent period. This work reports that the A. vasorum infection resulted in an increase of relative neutrophils and eosinophils counts. In contrast, there was a significant decrease in the alveolar macrophage relative count in infected animals from 60 to 330 dpi. This study shows that the BAL is an accurate technique for the diagnosis of canine angiostrongylosis. Moreover, the technique allows us to retrieve cells and other elements that line the lung surface for cytological evaluation, which provides information about inflammatory diseases, and the diagnosis and prognosis of pulmonary parasites such as A. vasorum.

Analysis of Circulating Haemocytes from Biomphalaria glabrata following Angiostrongylus vasorum Infection Using Flow Cytometry.

Angiostrongylus vasorum is an emerging parasite of dogs and related to carnivores that have an indirect life cycle, with a wide range of terrestrial and aquatic gastropods as the obligatory intermediate host. Unfortunately, the relationship between A. vasorum and their snail hosts remains poorly understood. Circulating haemocytes are the main line of cellular defence involved in the destruction of helminths in snails. Aiming to further characterize the haemocyte subsets in Biomphalaria snails, we have performed a flow cytometric analysis of whole haemolymph cellular components using a multiparametric dual colour labelling procedure. Our findings demonstrated that B. glabrata infected with A. vasorum have two major circulating haemocyte subsets, referred to as small and large haemocytes. Differences in the cell proportion occurred over time. The development of better invertebrate infection control strategies would certainly result in the better control of human diseases caused by other species of the genus Angiostrongylus. Such knowledge will assist in the establishment of novel control strategies aimed at parasites that use molluscs as intermediate hosts and clarify new aspects of the parasite-host relationship regarding cell recognition and activation mechanisms, which are also found in the innate response of vertebrates.

Parasitic Infections and Inflammatory Diseases

The mammalian immune system is continuously exposed to infectious microorganisms as well as innocuous substances in the environment. Depending on the genetic makeup, the innate and adaptive immune responses develop and determine the frequency and the course of infectious diseases. The immune response to an infection is initiated by molecular recognition of damage-associated patterns (DAMPs) by receptors of the innate immunity, that, most of the time, occurs as an inflammatory reaction (Turvey & Broide, 2010). The inflammation associated to parasite organisms is a complex reaction of the vascular tissues against infection, exposition to toxins or cellular injury involving extravascular accumulation of plasmatic proteins and leukocytes, as well as production of cytokines from the injured tissue. It is an essential component of multifactorial pathogenesis involved in different diseases (Scrivo et al., 2011). The acute inflammation is a common result of innate immune response; however local immune adaptative factors can also promote inflammation (Lukic et al., 2009). The morphologic transformations and functional characteristics of immunological responses and consequently, of the inflammatory processes intend to destroy, to dilute or to isolate the harmful agent. Virtually, all the acute or chronic diseases are lead or modulated by the inflammation. Although the inflammation serves to a protective function in the control of parasitic infections and promotion of tecidual repair, this can also cause injury and illness itself. Schistosomiasis is an exemple of parasitary disease caused predominantly by the host immune response to schistosome eggs (ova) and the granulomatous reaction they evoke (Burke et al., 2009). In some cases, the inflammation can even persist after the removal of the infectious agent, contributing to the chronic inflammation (Vodovotz et al., 2009). Amongst the various infectious agents, helminth parasites are regarded as master manipulators of the host immune system, often inducing a long-lasting asymptomatic form of infection. Parasitic worms can establish and reproduce in mammalian hosts, switching off the inflammatory immune response and inducing a tolerant response to parasite antigens. The time of duration and the intensity of the inflammatory agent determine different degrees or phases of transformation in tissues (Zaccone et al., 2006).