DNA Methylation Status of the Estrogen Receptor α Gene in Canine Mammary Tumors.

Estrogen receptor α (ERα) has an important role in mammary carcinogenesis, prognosis, and treatment. In human and canine mammary cancer, the most aggressive tumors show loss of ERα expression, which in human breast cancer has been attributed to methylation of the cytosine followed by guanine (CpG) island within the estrogen receptor α gene ( ESR1) promoter. This study aimed to investigate the role of ESR1 CpG island (CGI) methylation in ERα expression in canine mammary tumors. Twenty-one canine mammary samples were sorted into three groups: malignant tumor (n = 9), benign tumor (n = 8), and normal gland (n = 4). Immunohistochemical analysis and reverse-transcription quantitative real-time PCR were performed to assess ERα expression and ESR1 mRNA levels. The methylation status was determined using sodium-bisulfite-treated DNA sequencing. All normal mammary glands and benign tumors showed high ERα expression (score range, 5-8). Six of the nine malignant tumors did not show ERα expression (score 0), two had score 2, and one had score 4. Lower ERα ( P < .005) and ESR1 mRNA levels ( P < .005) were found in malignant mammary tumors than in the other two groups. Canine ESR1 has an intragenic and non-promoter-associated CGI, different from humans. No significant variation in methylation percentage was observed among the groups, suggesting that ESR1 is not regulated by DNA methylation, unlike that in humans. This difference should be considered in further research using ERα as a biomarker for mammary tumors in canine studies on ERα-targeting therapy.

Reduction of egg reappearance period of cyathostomins in naturally infected horses after increasing doses of ivermectin in Brazil: a grim picture for sustainable parasite control.

Cyathostomins are the largest group of parasites in horses that can be controlled by ivermectin (IVM). This study aimed to run a four-dose titration trial of IVM in 28 naturally infected Thoroughbred yearlings. The local Strongyle population had been recorded to be resistant to IVM (200 µg/kg). The parasite fecal egg count (FEC) was performed to investigate the egg reappearance period (ERP) of two and five weeks (w2pt and w5pt) after IVM treatment. FEC was > 1000 on day zero for all groups. Although 100% FEC reduction was reported at w2pt for all concentrations, the FEC at w5pt revealed < 83% efficacy. This study reports the reduction of ERP using the label dose as well as 300, and 400 µg/kg (double dose) of IVM. The protocol allowed IVM to significantly suppress FEC w2pt although not eliminating adult worms, failing to guarantee an extension of its protection period over 8 weeks. Moreover, the FEC at w5pt possibly means the infection was not cleared, and worms reestablished egg laying. We raised the possibility of withdrawing IVM of control programs when the drug has less than 80% FEC reduction at w5pt.

Geographic expansion of Fasciola hepatica (Linnaeus, 1758) due to changes in land use and cover in Brazil.

Fasciolosis is caused by parasites of the genus Fasciola, affecting animals and humans worldwide. In South America, the disease is a result of infection with Fasciola hepatica and although animal infections are more frequently reported, the full extent of the impact on human health due to underdiagnosis remains uncertain. This study analyzed changes in land use and the distribution of F. hepatica in bovine livers in Brazil over 18 years. Data on land use and land cover were collected from the Mapbiomas Project. Data on 414,481,963 slaughtered cattle and condemned livers due to F. hepatica infection were obtained from 4,433 municipalities. Joinpoint analysis was used to study the time series, and the Susceptible-Infected-Recovered (SIR) model was utilized to explore the behavior of F. hepatica infection. In the North, pasture areas significantly increased (P = 0.000001), while forested areas decreased (P = 0.000001). The midwestern and northern regions concentrated the highest number (>290 million) of cattle slaughtered in Brazil. More than 2 million bovine livers were infected by F. hepatica. The infected cattle originated from 194 municipalities in 2002, increasing to 747 in 2020. We consider that the changes in land use and intense cattle transportation may have caused the expansion of F. hepatica. The SIR model analyzed the spread of the disease looking at all six biomes: Caatinga, Amazon Forest, Cerrado, Pantanal, Atlantic Forest, and Pampa. Moreover, this infection not only threatens the health of animals but is also a major concern to biodiversity and vulnerable human communities in South America. Emblematic biomes such as the Amazon basin already face challenges with logging, desertification, and loss of biodiversity. Therefore, strategies for mitigating infection should include controlling illegal pasture areas, establishing health inspections of animal transport, quarantine of newly arrived animals, and livestock zoning, as well as clear One Health policies.

A Systematic Review of Apicomplexa Looking into Epigenetic Pathways and the Opportunity for Novel Therapies.

Interest in host epigenetic changes during apicomplexan infections increased in the last decade, mainly due to the emergence of new therapies directed to these alterations. This review aims to carry out a bibliometric analysis of the publications related to host epigenetic changes during apicomplexan infections and to summarize the main studied pathways in this context, pointing out those that represent putative drug targets. We used four databases for the article search. After screening, 116 studies were included. The bibliometric analysis revealed that the USA and China had the highest number of relevant publications. The evaluation of the selected studies revealed that Toxoplasma gondii was considered in most of the studies, non-coding RNA was the most frequently reported epigenetic event, and host defense was the most explored pathway. These findings were reinforced by an analysis of the co-occurrence of keywords. Even though we present putative targets for repurposing epidrugs and ncRNA-based drugs in apicomplexan infections, we understand that more detailed knowledge of the hosts' epigenetic pathways is still needed before establishing a definitive drug target.

Macrocyclic lactone resistance in nematodes of cattle in Brazil: Blame it to the ticks!

Strategic helminth control in adult cattle would hardly impose sufficient selection pressure to parasite populations but reports of resistance against macrocyclic lactone (ML) based-products have been confirmed worldwide. The objective of this study was to evaluate the scientific literature of ML resistance (< 90.0% efficiency) in helminths of cattle from 2001 (the first report) to 2020 in Brazil. Additional to the data, we studied the correlation of parasite control practices based on a questionnaire given to 32 farmers. The search returned 246 reports and 21 full articles were selected. From these, a Wordcloud and a Keyword Co-occurrence Network graph were created. The published data revealed that most of the studies (19/21) reported multi-species (Cooperia spp., Haemonchus sp., Oesophagostomum radiatum, Trichostrongylus sp.) resistance to ML. None of the reports described the treatment frequency in the tested farms. As for the questionnaire, the majority of farmers (> 70.0%) responded that they rotate products after treatment, animals are treated monthly or biweekly (58.0%), treatments are based on visual evaluation (coat condition, ectoparasite infestation), and that in 94.0% of the times farmers treat all animals. Moreover, farmers use ML in association with potent acaricides (cypermethrin, chlorpyriphos, fluazuron) in more than 90.0% of the times (15/16). It was observed that this regimen was used to prevent and control the cattle-tick Rhipicephalus microplus (90.0%) and the horn-fly, Haematobia irritans (30.0%) infestations. We conclude that the most important factor for nematode resistance was the high level of ML exposure of up to 16 times/year, in combination with acaricides to control ticks and to a lesser extent to control horn-flies. Therefore, selection of helminth populations in cattle in Brazil can be considered secondary to ectoparasite control. The present analysis is critical, as one the most widespread recommendations to avoid drug resistance is to reduce the use of long-acting compounds, due to their extended persistent periods, increasing parasite selection. Moreover, a more serious attitude must be taken regarding parasite control strategies for livestock, reinforcing that health protocols should be based on single acaricidal products whenever possible. Complementary, selective evaluations based on transient threshold population abundance must be enforced to reduce treatment frequency, reducing parasite selection and animal distress.

Oxidative stress in hoof laminar tissue of horses with lethal gastrointestinal diseases.

Tissue damage caused by oxidative stress is involved in the pathogenesis of several diseases in animals and man, and is believed to play a role in the development of laminitis in horses. The aim of this study was to investigate the oxidative stress associated with laminar lesions in horses with lethal gastrointestinal disorders. Laminar tissue samples of the hoof of 30 horses were used. Tissue samples were divided as follows: six healthy horses (control group-CG), and 24 horses that died after complications of gastrointestinal diseases (group suffering from gastrointestinal disorders-GDG). Superoxide dismutase (SOD2) and nitrotyrosine immunostaining and the severity of laminar lesions were evaluated. Presence of laminar lesions and immunostaining for nitrotyrosine and SOD2 were only evident in horses from the GDG group. Thus, oxidative stress may play a role in the pathogenesis of laminar lesions secondary to gastrointestinal disorders.