Mononuclear cell subsets in bronchoalveolar lavage fluid during Dictyocaulus viviparus infection of calves: a potential role for gamma/delta TCR-expressing cells in airway immune responses?

Lungworms in ruminants from Brazil: A retrospective epidemiological study over four decades

Lungworms such as Dictyocaulus spp. in cattle and small ruminants, and Muellerius capillaris and Protostrongylus rufescens in small ruminants are important pathogens, causing respiratory disease in these livestock species. Despite their veterinary importance, lungworms of livestock have been poorly studied in certain regions of the world, including Brazil. Therefore, much of their epidemiology and economic impacts on production remain unknown. This article aims to provide a comprehensive overview of the historical and current data published on lungworm infection of domestic ruminants in Brazil. This review consisted of a comprehensive search of technical and scientific publications between January 1980 to December 2020, using online sources such as PubMed, Google Scholar and Scielo. Twenty-four articles published over the last 40 years reporting lungworms exclusively in cattle (n = 16), goats (n = 6) and sheep (n = 1) in Brazil were included. In addition, a study (n = 1) with both goats and sheep were also utilized. Overall, 12 studies were based only on post-mortem examination, five in the detection of specimens in fecal samples, and seven were based on fecal analysis followed by post-mortem examination. Out of all studies, 66.7% (n = 16) articles registered D. viviparus, 4.2% (n = 1) D. filaria, 8.3% (n = 2) P. rufescens, 16.7% (n = 4) M. capillaris, and 4.2% (n = 1) co-infection by D. filaria and M. capillaris. The existence of suitable environmental conditions, as well as intermediate and definitive hosts in Brazil contribute for the survival and development of these nematode species. The majority of the reports of lungworms originate from the Southern and Southeastern regions of the country, whose mild temperatures likely contribute to their occurrence. Finally, lungworms of ruminants have been reported over the past four decades in Brazil, but most of the information was obtained at post-mortem examination. Therefore, further studies to investigate epidemiological aspects in different hosts and regions of the country are needed.

Diagnosis of bovine dictyocaulosis by bronchoalveolar lavage technique: A comparative study using a Bayesian approach

Bovine dictyocaulosis is a pulmonary parasitic disease present in temperate countries, with potential important clinical and economic impacts. The Baermann technique is routinely used despite its low sensitivity in adult cows. Recently developed serological tests seem to offer better sensitivity, but validations of these tests in field conditions are few. We aimed to study two non-previously evaluated diagnosis methods of dictyocaulosis based on bronchoalveolar lavage sampling (BAL), which allows finding lungworm stages in the lungs as well as determination of eosinophilia. We compared them to the Baermann technique and serological tests. As no gold standard was available, we performed a Bayesian analysis by the simultaneous use of latent class and mixture models. The study was carried out during the 2015 pasture season on 60 adult cows originating from 11 herds with clinical signs of dictyocaulosis, and 10 apparently healthy cows originating from the teaching herd of VetAgro Sup, in France. Prevalence of infection was highly variable among herds with clinical signs (10-90%). Despite a maximal specificity (100%), the sensitivity of parasitological methods was low (7.4% for the Baermann sedimentation and 24.7% for the examination of BAL fluids). Better results were observed with serology (Se = 74.9%, Sp = 85.5%) with an optimal cut-off value estimated at 0.397 for the optical density ratio. Even better results were obtained with the count of eosinophil in BAL (Se = 89.4%, Sp = 85.2%) with an optimal cut-off value estimated at 4.77% for the eosinophil proportion. The BAL is a relevant diagnostic method of dictyocaulosis for practitioners due to the opportunity to perform two analyses (direct parasitic research and the eosinophil count) and to its good sensitivity and specificity.

WITHDRAWN: Co-administration of CCL5 and IL4 enhances DNA vaccine-induced protective immunity to Ascaris suum infection in mice

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γδ T Lymphocytes Coordinate Eosinophil Influx during Allergic Responses

Tissue eosinophil infiltration, which is a hallmark of allergic and helminthic diseases, is mainly coordinated by T lymphocytes, via the production of eosinophilotactic chemokines. Among T lymphocyte subsets, lymphocytes expressing γδ T cell receptor have been determined as a key factor for eosinophil accumulation via direct and indirect mechanisms. This knowledge is strongly supported by the fact that, in different experimental models of eosinophilic airway inflammation and helminth-induced Th2 lung inflammation, an evident tissue accumulation of γδ T lymphocytes is observed. In addition, the depletion of γδ T lymphocytes is correlated with the impairment of eosinophil accumulation in inflamed tissue. γδ T lymphocytes are non-conventional T lymphocytes, which comprise a minor T lymphocyte subset, mainly distributed in the tissue, and present crucial roles in innate and acquired immune responses. γδ T lymphocytes recognize several danger- and pathogen-associated molecular pattern molecules and stress antigens in a MHC-independent fashion and can provide rapid tissue-specific responses, via the production of a wide range of chemical mediators capable to modulate other cell populations. These mediators include chemoattractant cytokines and chemokines that attract eosinophils into the tissue by either direct recognition (such as IL-5, CCL11/eotaxin), or indirect mechanisms via the modulation of αβ T lymphocytes and macrophages (through the production of interferon-γ, IL-4, and CCL2/Monocyte chemoattractant protein-1, MCP-1, for example). The present review presents an overview of how γδ T lymphocytes coordinate eosinophil accumulation in allergy, by focusing on their role in airway inflammation and by discussing the involvement of cytokines and chemokines in this phenomenon.

The immune response to parasitic helminths of veterinary importance and its potential manipulation for future vaccine control strategies

Despite the increasing knowledge of the immunobiology and epidemiology of parasitic helminths of the gastrointestinal system and the cardiorespiratory system, complications arising from infections of animals and humans with these parasites are a major clinical and economic problem. This has been attributed to the high incidence of these parasites, the widespread emergence of multi-drug resistant parasite strains and the lack of effective vaccines. Efforts to develop and produce vaccines against virtually all helminths (with the exception of Dictyocaulus viviparus and some cestode species) have been hindered by the complexity of the host-parasite relationship, and incomplete understanding of the molecular and immune regulatory pathways associated with the development of protective immunity against helminths. Novel genomic and proteomic technologies have provided opportunities for the discovery and characterisation of effector mechanisms and molecules that govern the host-parasite interactions in these two body systems. Such knowledge provided clues on how appropriate and protective responses are elicited against helminths and, thus, may lead to the development of effective therapeutic strategies. Here, we review advances in the immune response to selected helminths of animal health significance, and subsequent vaccine potential. The topics addressed are important for understanding how helminths interact with host immune defences and also are relevant for understanding the pathogenesis of diseases caused by helminths.