Bovine leukemia virus (BLV) causes a long subclinical infection and can result in B-cell leukemia/lymphoma. However, the in vivo relationship between expression of the BLV antisense transcript AS1 and the sense transcripts, tax/rex or env, and how these relate to host immune responses and lymphoma onset, remains unclear. We used an experimental model of sheep BLV infection to analyze whole blood longitudinally in the proximal (up to 40 days post-inoculation) and late phase (starting 6 months prior to lymphoma onset) of infection, up to and including lymphoma onset. We observed a stereotypical pattern of viral transcript expression, starting with tax/rex and env, followed by AS1-S/L transcription. Proviral load (PVL) in the blood and percentage of infected cells were elevated from 10 to 20 days post-inoculation and coincided roughly with AS1-S/L expression, and BLV-antibody induction occurred soon thereafter. In the late phase of infection, tax/rex was constitutively expressed at 6 months before onset and decreased as lymphoma onset approached. In contrast, PVL, the proportion of infected cells, AS1-S/L, and expression of the anti-inflammatory cytokine IL-10 increased at lymphoma onset, while IFN-γ decreased. These findings indicate that sense (tax/rex) and antisense (AS1-S/L) transcription are differentially regulated in BLV-infected sheep, with the increased viral burden at lymphoma onset being associated with monoclonal expansion of circulating BLV-infected cells. In particular, the development of lymphoma appears to be associated with AS1-S/L transcription and changes in immune indicators consistent with reduced T-cell-mediated immune activity.
The human melanoma-associated lymphocytic inflammatory infiltrate is considered a prognostic factor; however, this relationship remains poorly established in canine melanomas. Thus, this study aimed to evaluate 117 canine melanomas from different locations (oral cavity/digital - n = 74; cutaneous melanomas - n = 43) using morphological and morphometric analyses of inflammatory cells, CD4 + and FoxP3 + lymphocyte population, and survival rates. Regardless of location, most canine melanomas presented a low frequency of associated inflammatory response. However, when present, the inflammation was discrete, with a focal/multifocal distribution, predominantly lymphocytic, frequent in larger tumors, and associated with higher survival rates. Inflammation was more frequent in oral/digit tumors. Still, it was associated with a milder profile than infiltrates in cutaneous melanomas, with lymphocytes as the predominant cell type and a higher frequency of CD4 + and FoxP3 + cells in more extensive and aggressive tumors. These results indicate that aggressive tumors elicit an immune response, but it is associated with a regulatory profile.
Arachidonic acid released from phospholipids in the cell membrane, is used to synthesize lipid mediators known as leukotrienes (LTs). LTs play a key role in numerous leukocyte functions including leukocyte migration and inflammation. However, their function in the avian central nervous system is poorly understood. Thus, this study investigated whether lipopolysaccharide (LPS) a cell wall component of Gram-negative bacteria modulates LT synthesis via 5-LOX, an LT synthase, in chicks (Gallus gallus). Intraperitoneal LPS injection substantially increased 5-LOX mRNA expression in the diencephalon, thymus, and bursa of Fabricius, but decreased its expression in the spleen. Subsequently, we investigated the main effects of LTs on behavioral, physiological, and immunological responses in chicks. Intracerebroventricular (ICV) injection of LTB4 and LTC4 did not affect food intake. Furthermore, ICV injection of LTB4 and LTC4 did not affect cloacal temperature, plasma constituents, or crop-emptying rate. ICV injection of LTB4 considerably reduced the mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), interleukin-1β (IL-1β), and IL-6 in the diencephalon. However, expression of IL-8 mRNA was substantially increased by LTB4. Similarly, LTC4 injection notably decreased IL-1β mRNA expression in the diencephalon and tended to decrease COX-2 mRNA expression. This study suggests that LPS might affect the synthesis of LTs in the diencephalon, and these LTs might subsequently affect the diencephalic immune response in chicks.
Canine macrophages are increasingly recognized as important regulators of tumor immunity; however, in vitro culture systems that minimize serum-derived variability remain limited. In this study, we established a serum-reduced culture system for canine peripheral blood mononuclear cell (PBMC)-derived macrophages and characterized their phenotypic, transcriptional, and functional properties. PBMCs from healthy Beagle dogs (n = 3) were differentiated into M0, M1, and M2 macrophages using Macrophage Base Medium supplemented with canine serum or recombinant cytokines. Morphology was assessed by phase-contrast microscopy, macrophage identity was evaluated by Iba1 immunostaining and AIF1 expression, and exploratory transcriptomic profiles were examined by RNA sequencing (n = 1). Phagocytic activity was assessed using FITC-labeled latex beads and flow cytometry, and macrophage–tumor cell interactions were evaluated by co-culture with canine urothelial carcinoma cells. M0, M1, and M2 macrophages exhibited distinct morphologies and transcriptional patterns. M1 macrophages showed increased expression of inflammatory genes, including IL1B and IFNG, whereas M2 macrophages showed increased expression of genes associated with alternative activation and immune regulation, including CD209, CD5L, and IL33. Phagocytic activity was observed in all subsets. In co-culture experiments, macrophages exhibited polarization-dependent interaction patterns with tumor cells, with M2 macrophages exhibiting features reminiscent of tumor-associated macrophages. These findings provide a pilot evaluation of this serum-reduced culture system, which generates phenotypically distinct canine macrophage subsets and may serve as a useful in vitro platform for future studies of canine macrophage polarization and tumor-associated immune responses.
Staphylococcus chromogenes is one of the most prevalent non-aureus staphylococci associated with persistent intramammary infections (IMIs) in dairy cattle. However, the local cellular immune response to naturally occurring S. chromogenes IMI remains poorly characterized. Thus, this study aimed to assess milk T cell subsets, macrophages, neutrophils, and key intracellular cytokine production by milk T cells in mammary gland quarters naturally infected with S. chromogenes. Milk samples were used from non-infected and S. chromogenes-infected quarters from clinically healthy Holstein-Friesian dairy cows. The intensity of intracellular IFN-γ production by CD4+ (P = 0.048) and CD8+ (P = 0.035) T lymphocytes was higher in S. chromogenes-infected quarters than in non-infected controls, with a similar trend observed for γδ T cells (P = 0.06). Furthermore, the proportion of milk γδ T cells was higher in S. chromogenes-infected quarters (P = 0.05). Differences were observed neither in intracellular IL-17A production by T cell subsets nor in the proportions of milk CD4+ and CD8+ T lymphocytes, macrophages and neutrophils. Our findings identify T cell responses as a key component of the mammary immune response to S. chromogenes IMI and open new avenues for future studies investigating its potential in vivo protective response against major mastitis pathogens.
