Cytokine mRNA expression in bronchoalveolar lavage cells duringDictyocaulus viviparusinfection in calves

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.

Evaluation of the immune status of peripheral blood monocytes from dairy cows during the periparturition period

Calving is a critical but stressful event required for milk production in dairy cows. In the present study, we investigated the immune status of peripheral blood mononuclear cells (PBMCs) isolated from periparturient cows to better understand and, thus, possibly prevent stress during the periparturient period. To evaluate the immune response of PBMCs, we assessed their proliferation with or without a mitogen (concanavalin A, ConA). Blood samples were collected 24 h before and after calving and 1 week after calving. The proliferation of non-treated cells remained unchanged throughout the examination period. The immune response of PBMCs isolated from the cows before calving was relatively low, even after ConA stimulation; however, the immune response of PBMCs collected at both time points after calving was significantly higher than those of non-stimulated controls. Next, we examined the expression patterns of T cell related and inflammatory cytokine genes in PBMCs. We found that the mRNA expression levels of both CD4 and CD8 showed decreasing trends after calving. The expression of the Th1 cell marker gene IFNG also decreased after calving. The mRNA expression level of the inflammatory cytokine gene TNFA increased after parturition. Overall, our results suggest that the PBMC immune response was weakened in cows before delivery and part of the expression of the immune cell-related genes in these cells is altered 24 h before and after calving.

Alveolar macrophage functions during the transition phase to active immunity in calves1

The first 3 to 6 mo of the life of calves is the period during which active immunity is established. During this period, greater morbidity and mortality is caused by bronchopneumonia because of the immaturity of the pulmonary immune system or the exaggerated cytotoxic response at subsequent infection. The aim of this study was to examine the maturity of the immune system during this phase of activation of acquired immunity in calves. For this purpose, the functions of phagocytosis and the reactive oxygen species (ROS) of alveolar macrophages CD14+ were evaluated. Further, the classes of immunoglobulins and the cytokines implicated in lymphocyte response patterns Th1 and Th2 in 10 healthy Holstein calves were quantified. Samples were taken from calves every 15 d, from the third to the sixth month of life. The alveolar macrophage CD14+ functions increased progressively until 150 d of age (phagocytosis, P = 0.02, ROS, P = 0.05), IgG1 and IgG2 isotype secretion reached an equilibrium, and the cytokine profiles were compatible with the Th1 response. At 165 d of age, there was a decrease in cellular function (phagocytosis P = 0.02, ROS P = 0.04) and an increase in IgG1 titers (P = 0.005) and IL-10 mRNA expression (P = 0.09). At 180 d of life, we observed an IgG1 and IgG2 secretion balance, a decrease in IL-10 mRNA expression, and an increase in IL-12 mRNA (P = 0.04) and tumor necrosis factor (TNF)-α mRNA expressions (P = 0.0003) and alveolar macrophage oxidative metabolism were observed. These results indicate that the calves had an active immune response that was distinctive for the age group. The CD14+ response is more reactive at 150 d. A regulatory and/or humoral response begins at 165 d of life as the equilibrium of Th1 and Th2 profiles is reached at 180 d of life. This may be clinically relevant for the development of specific therapies and prophylactic measures for bronchopneumonia in calves at 135 to 180 d of life.

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.