Clinical Implications of Immune Checkpoints and the RANK/RANK-L Signaling Pathway in High-Grade Canine Mast Cell Tumors

Mast cell tumors (MCTs) are the most common malignant cutaneous tumors in dogs, and they present extremely variable biological behavior. The interaction between RANK, RANK-L, and immune checkpoints is frequently detected in the tumor microenvironment, and, together, they participate in every stage of cancer development. Thus, the aim of this study was to characterize the molecular profiles of PD-L1, CTLA-4, RANK/RANK-L signaling pathway, and IFN-γ in primary tumors and lymph node metastases. Formalin-fixed, paraffin-embedded slides of MCTs and metastatic lymph nodes of ten dogs were submitted to immunohistochemical investigations. The results demonstrated that the tumor microenvironment of the high-grade mast cell tumors showed moderate or intense immunolabeling of all proteins, and the lymph node metastases also showed moderate or intense immunolabeling of checkpoint proteins. In addition, MCTs larger than 3 cm were associated with intensified PD-L1 (p = 0.03) in metastatic lymph nodes and RANK-L (p = 0.049) immunoreactivity in the tumor. Furthermore, dogs with a survival time of less than 6 months showed higher PD-L1 immunoreactivity (p = 0.042). In conclusion, high-grade MCT is associated with an immunosuppressive microenvironment that exhibits elevated RANK/RANK-L signaling and enhanced immune checkpoint immunoreactivity, potentially facilitating intratumorally immune escape. These biomarkers show promise as clinical indicators of disease progression and might response to immunotherapy in dogs with high-grade MCTs, thus emphasizing their importance for guiding treatment decisions and improving outcomes.

Effects of low-intensity pulsed ultrasound on wound healing in corneas of dogs following keratoplasty

The effects of low-intensity pulsed ultrasound on wound healing were evaluated at the graft-cornea transition in dogs following lamellar keratoplasty using tunica vaginalis preserved in 98% glycerin. Twenty-one dogs were subdivided into three groups of seven animals. The first group (W/US) received daily treatment of low-intensity pulsed ultrasound (20 mW/cm2) for 15 min for the first 10 days post surgery. The second group (N/US) was submitted to the same procedure but with the ultrasound apparatus turned off. The third group, the control (CO), underwent the surgical procedure only. The animals were clinically evaluated during the initial (1-15 days), intermediate (16-30 days) and late (31-120 days) postoperative period. The corneas were evaluated by light microscopy at 1, 3, 7, 15, 30, 60 and 120 days after surgery. Clinically, there were no differences which would promote an advantage to any of the treatments. Light microscopy, however, revealed more extensive vascularization and more advanced wound healing in the W/US group, as well as a tendency towards early graft incorporation. Based on the present results, low-intensity pulsed ultrasound shows advantages, especially in situations where trophic support is a mandatory condition, facilitating better graft incorporation and rapid recovery of stromal organization.

Utilização de implante ósseo cortical alógeno conservado em glicerina para preservação de membro torácico: estudo experimental em cães

A técnica de preservação de membro é uma alternativa à amputação em cães com osteossarcoma do esqueleto apendicular. OBJETIVO: O desenvolvimento da técnica preservadora aos moldes da original descrita por Straw¹. MÉTODOS: O procedimento cirúrgico foi realizado com modificações, substituindo-se o método de conservação dos implantes pela glicerina e o cimento ósseo utilizado no preenchimento do canal medular do implante pela poliuretana de mamona, e para avaliação da incorporação do implante foram feitos exames clínico, radiográfico e histopatológico em diferentes tempos pós-operatórios. RESULTADOS: Observada a boa função do membro no pós-operatório, a formação de calo ósseo e fechamento das linhas de interfaces com remodelação óssea em avaliação radiográfica e ao exame histopatológico foi notada a reabsorção do implante ósseo com sua substituição por tecido conjuntivo fibroso e tecido ósseo compacto, neovascularização e presença de infiltrado inflamatório plasmocitário. CONCLUSÕES: A poliuretana de mamona mostrou-se uma boa substituta ao cimento originalmente utilizado, aumentando a resistência do implante, sem causar reações do tipo corpo estranho e sem sua osteointegração. O implante ósseo conservado em glicerina apresentou ação osteoindutora e osteocondutora, sem sinais de rejeição; desta forma, a glicerina mostrou ser uma meio alternativo viável. Portanto, a técnica de preservação do membro, com suas modificações, caracterizou-se como alternativa à técnica original e à amputação do membro para cães com osteossarcoma de esqueleto apendicular.