Density of tumor-infiltrating granzyme B-positive cells predicts favorable prognosis in dogs with transitional cell carcinoma

Tumor-Infiltrating Lymphocytes and Neutrophils and Their Location in Canine Mammary Neoplasms with a Solid Arrangement: A Prognostic Factor?

In canine mammary neoplasms, greater inflammation is associated with higher histological grade, lymphatic invasion, and metastases. This retrospective study assessed the density of peri- and intratumoral tumor-infiltrating lymphocytes (TILs), tumor-associated neutrophils (TANs), and CD3+ and CD79+ lymphocytes in canine mammary neoplasms with a solid arrangement, and associated such data with histological types, immunophenotype, prognostic factors, cyclooxygenase-2 (Cox-2) expression and overall and cancer-specific survival. Sixty-one neoplasms with a solid arrangement were classified as malignant myoepitheliomas (6/9.8%), solid papillary carcinomas (8/13.1%), carcinomas with a solid pattern (9/14.8%), basaloid carcinomas (BC) (19/31.1%), and malignant adenomyoepitheliomas (19/31.1%). Intra- and peritumoral TILs, TANs, and TCD3+ and BCD79+ lymphocytes were counted, and based on the resulting median, the neoplasms were divided into low or high cell infiltration. BCs had the lowest density of intratumoral TILs (p = 0.02), and luminal B neoplasms showed a significantly higher density of intratumoral TCD3+ than luminal A cases. Neoplasms with a higher density of peritumoral CD3+ and CD79+ had significantly greater proliferative activity. High infiltration of intratumoral BCD79+ lymphocytes was related to nodal metastasis (p = 0.03). Intratumoral TILs and TCD3+ were associated with shorter survival time. Therefore, intratumoral lymphocyte infiltration is possibly an important feature in the progression of cancer and influences the survival in bitches with solid arrangement neoplasms.

Comprehensive Analysis of the Tumour Immune Microenvironment in Canine Urothelial Carcinoma Reveals Immunosuppressive Mechanisms Induced by the COX-Prostanoid Cascade

A comprehensive understanding of the tumour immune microenvironment (TIME) is essential for advancing precision medicine and identifying potential therapeutic targets. This study focused on canine urothelial carcinoma (cUC) recognised for its high sensitivity to cyclooxygenase (COX) inhibitors. Using immunohistochemical techniques, we quantified the infiltration of seven immune cell populations within cUC tumour tissue to identify clinicopathological features that characterise the TIME in cUC. Our results revealed several notable factors, including the significantly higher levels of CD3+ T cells and CD8+ T cells within tumour cell nests in cases treated with preoperative COX inhibitors compared to untreated cases. Based on the immunohistochemistry data, we further performed a comparative analysis using publicly available RNA-seq data from untreated cUC tissues (n = 29) and normal bladder tissues (n = 4) to explore the link between COX-prostanoid pathways and the immune response to tumours. We observed increased expression of COX-2, microsomal prostaglandin E2 synthase-1 (mPGES-1) and mPGES-2 in cUC tissues. However, only mPGES-2 showed a negative correlation with the cytotoxic T-cell (CTL)-related genes CD8A and granzyme B (GZMB). In addition, a broader analysis of solid tumours using The Cancer Genome Atlas (TCGA) database revealed similar patterns in several human tumours, suggesting a common mechanism in dogs and humans. Our results suggest that the COX-2/mPGES-2 pathway may act as a cross-species tumour-intrinsic factor that weakens anti-tumour immunity, and that COX inhibitors may convert TIME from a 'cold tumour' to a 'hot tumour' state by counteracting COX/mPGES-2-mediated immunosuppression.

Quantification of CD3, FoxP3, and granzyme B immunostaining in canine renal cell carcinoma

Tumor-infiltrating lymphocyte (TIL) density plays an important role in anti-tumor immunity and is associated with patient outcome in various human and canine malignancies. As a first assessment of the immune landscape of the tumor microenvironment in canine renal cell carcinoma (RCC), we retrospectively analyzed clinical data and quantified CD3, FoxP3, and granzyme B immunostaining in formalin-fixed paraffin-embedded tumor samples from 16 dogs diagnosed with renal cell carcinoma treated with ureteronephrectomy. Cell density was low for all markers evaluated. Increased numbers of intratumoral FoxP3 labelled (+) cells, as well as decreased granzyme B+: FoxP3+ TIL ratio, were associated with poor patient outcomes. Our initial study of canine RCC reveals that these tumors are immunologically cold and Tregs may play an important role in immune evasion.

Comparative Evaluation of Tumor-Infiltrating Lymphocytes in Companion Animals: Immuno-Oncology as a Relevant Translational Model for Cancer Therapy

Despite the important role of preclinical experiments to characterize tumor biology and molecular pathways, there are ongoing challenges to model the tumor microenvironment, specifically the dynamic interactions between tumor cells and immune infiltrates. Comprehensive models of host-tumor immune interactions will enhance the development of emerging treatment strategies, such as immunotherapies. Although in vitro and murine models are important for the early modelling of cancer and treatment-response mechanisms, comparative research studies involving veterinary oncology may bridge the translational pathway to human studies. The natural progression of several malignancies in animals exhibits similar pathogenesis to human cancers, and previous studies have shown a relevant and evaluable immune system. Veterinary oncologists working alongside oncologists and cancer researchers have the potential to advance discovery. Understanding the host-tumor-immune interactions can accelerate drug and biomarker discovery in a clinically relevant setting. This review presents discoveries in comparative immuno-oncology and implications to cancer therapy.

Exploring the association of intratumoral immune cell infiltrates with histopathologic grade in canine mast cell tumors

Cutaneous canine mast cell tumors (ccMCTs) vary in their biological behavior, treatment, and prognosis, based on their grade. Immune cell infiltration has been associated with prognosis and response to treatments in some human cancers, and immune-targeting therapeutics are increasingly being explored in veterinary oncology. However, currently little is known about the tumor microenvironment (TME) in ccMCTs. Therefore, the objective of this study was to determine the prevalence of T lymphocytes, T regulatory lymphocytes, PD-1+ cells and macrophages in low- and high-grade ccMCTs. Thirty low-grade and 20 high-grade formalin-fixed paraffin-embedded ccMCT samples were included. Immunohistochemistry (IHC) was performed to detect CD3, FOXP3, Iba1, and PD-1 on sequential sections. Three 400x fields with the highest numbers of CD3+ cells were identified for each tumor. The percentage of CD3+, FOXP3+, and Iba1+ cells, and the number of PD-1+ cells, was quantified in each of these three "hot-spot" fields using ImageJ software. Iba1 expression was significantly greater in high-grade compared to low-grade ccMCTs (mean = 12.5% vs. 9.6%, p = 0.043). PD-1 expression was low overall, but a significantly higher number of PD-1-expressing cells was observed in high-grade ccMCTs (median 1 vs. 0, p = 0.001). No significant difference was noted in CD3 and FOXP3 expression between ccMCT grades. Macrophages and PD-1+ cells were more frequent in high-grade, compared to low-grade ccMCTs. Further studies are needed to define the role of macrophages and rare PD-1+ cells in high-grade ccMCTs.

Are owned dogs or stray dogs more prepared to diseases? A comparative study of immune system gene expression of perforin and granzymes

Stray dogs are inevitably exposed to more infections than owned dogs living indoor. However, no studies have investigated whether the immune system gene expression differs between owned dogs kept in better care conditions and stray dogs living outside. To investigate this, blood samples were taken from 90 dogs (45 owned and 45 stray dogs) that were checked and confirmed as healthy. By using qPCR, the amples were analyzed for the expression of the perforin, granzyme A and granzyme B genes, which are associated with the activation of apoptotic pathways in the immune system. We found that the perforin and granzyme A gene expression levels were higher in stray dogs although the differences were not statistically significant. On the other hand, a 2.81 times higher and a notable difference (P < 0.001) was found in the expression level of granzyme B gene in stray dogs. These results indicate that the immune system in stray dogs might be more prepared for diseases than that of the owned dogs and the granzyme B gene plays a more dominant role in the immune response than granzyme A and perforin.

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

Cancer of the urinary bladder is a neoplasm with considerable importance in veterinary medicine, given its high incidence in several domestic animal species and its life-threatening character. Bladder cancer in companion animals shows a complex and still poorly understood biopathology, and this lack of knowledge has limited therapeutic progress over the years. Even so, important advances concerning the identification of tumour markers with clinical applications at the diagnosis, prognosis and therapeutic levels have recently been made, for example, the identification of pathological BRAF mutations. Those advances are now facilitating the introduction of targeted therapies. The present review will address such advances, focusing on small animal oncology and providing the reader with an update on this field. When appropriate, comparisons will be drawn with bladder cancer in human patients, as well as with experimental models of the disease.

Detection of granzyme B in CD3-positive cells infiltrated in lesional skin of a dog with erythema multiforme associated with zonisamide

In human erythema multiforme (EM), cytotoxic T lymphocytes (CTLs) play an essential role in the pathogenesis. In canine EM, immunohistochemical staining with anti-CD8 antibody using frozen sections has shown the involvement of CTLs; however, CTL infiltration has never been quantitatively analyzed. We herein quantitatively analyzed CTL infiltration by immunohistochemical staining with granzyme B and CD3 antibodies using paraffin sections of a dog with EM associated with zonisamide. The present results indicated approximately 70% of cells at the border between the epidermis and dermis consisted of CTLs. Detection of granzyme B and CD3 using paraffin sections employed in this study can be a clinically applicable method for detecting CTLs.

BRAFV595E Mutation Associates CCL17 Expression and Regulatory T Cell Recruitment in Urothelial Carcinoma of Dogs

Regulatory T cells may serve as targets in cancer immunotherapy. A previous study showed that the chemokine CCL17 and the receptor CCR4 play roles in regulatory T cell recruitment in canine urothelial carcinoma. In this article, we show that the BRAF^V595E mutation is associated with tumor-produced CCL17 and regulatory T cell infiltration in dogs with urothelial carcinoma. In comparison with healthy dogs, dogs with urothelial carcinoma showed increased CCL17 mRNA expression in the bladder and elevated CCL17 protein concentration in urine. Immunohistochemistry showed increased levels of Foxp3⁺ regulatory T cells in the tumor tissues of urothelial carcinoma. The density of Foxp3⁺ regulatory T cells was positively correlated with CCL17 concentration in urine, indicating that CCL17 is involved in regulatory T cell recruitment. Moreover, tumor-infiltrating regulatory T cells and urine CCL17 concentration were associated with poor prognosis in dogs with urothelial carcinoma. The number of tumor-infiltrating regulatory T cells, CCL17 mRNA expression, and urine CCL17 concentration in cases with BRAF^V595E mutation were higher than those in cases with wild-type BRAF. In vitro, high CCL17 production was detected in a canine urothelial carcinoma cell line with BRAF^V595E mutation but not in an urothelial carcinoma cell line with wild-type BRAF. Dabrafenib, a BRAF inhibitor, decreased CCL17 production in the cell line with BRAF^V595E mutation. These results suggest that BRAF^V595E mutation induced CCL17 production and contributed to regulatory T cell recruitment in canine urothelial carcinoma.

Tumour-infiltrating lymphocytes in canine melanocytic tumours: An investigation on the prognostic role of CD3+ and CD20+ lymphocytic populations

The study of the immune response in several types of tumours has been rapidly increasing in recent years with the dual aim of understanding the interactions between neoplastic and immune cells and their importance in cancer pathogenesis and progression, as well as identifying targets for cancer immunotherapy. Despite being considered one of the most immunogenic tumour types, melanoma can progress in the presence of abundant lymphocytic infiltration, therefore suggesting that the immune response is not able to efficiently control tumour growth. The purpose of this study was to investigate whether the density, distribution and grade of tumour-infiltrating lymphocytes (TILs) in 97 canine melanocytic tumours is associated with histologic indicators of malignancy and can be considered a prognostic factor in the dog. As a further step in the characterization of the immune response in melanocytic tumours, an immunohistochemical investigation was performed to evaluate the two main populations of TILs, T-lymphocytes (CD3⁺ ) and B-lymphocytes (CD20⁺ ). The results of our study show that TILs are present in a large proportion of canine melanocytic tumours, especially in oral melanomas, and that the infiltrate is usually mild. The quantity of CD20⁺ TILs was significantly associated with some histologic prognostic factors, such as the mitotic count, the cellular pleomorphism and the percentage of pigmented cells. Remarkably, a high infiltration of CD20⁺ TILs was associated with tumour-related death, presence of metastasis/recurrence, shorter overall and disease-free survival, increased hazard of death and of developing recurrence/metastasis, hence representing a potential new negative prognostic factor in canine melanocytic tumours.

Anti-tumor effects of the histone deacetylase inhibitor vorinostat on canine urothelial carcinoma cells

Canine urothelial carcinoma (cUC) is the most common tumor of the lower urinary tract in dogs. Although chemotherapy and radical surgery have improved the overall survival, most dogs with cUC succumb to metastasis or recurrence. Therefore, the development of an effective systematic therapy is warranted. In this study, a comprehensive drug screening test using a cUC cell line was performed and the anti-tumor effect of a histone deacetylase (HDAC) inhibitor was evaluated. Comprehensive drug screening was performed on cUC cells. Based on this screening, the anti-proliferation effect of vorinostat, an HDAC inhibitor clinically applied in humans, was evaluated using several cUC cell lines in sulforhodamine B and flow cytometry assays. Western blot analysis was also performed to evaluate the degree of acetylation of histone H3 as well as the expression and phosphorylation of cell cycle-related molecules. The anti-tumor effect of vorinostat in vivo was evaluated using a xenograft model. Finally, immunohistochemistry was performed on acetyl-histone H3 in cUC and the relationship between the degree of acetylation and prognosis was examined using Kaplan–Meier survival analysis. Drug screening revealed that HDAC inhibitors consistently inhibited the growth of cUC cells. Vorinostat inhibited the growth of 6 cUC cell lines in a dose-dependent manner and induced G0/G1 cell cycle arrest. Western blot analysis showed that vorinostat mediated the acetylation of histone H3, the dephosphorylation of p-Rb, and the upregulation of p21 upon exposure to vorinostat. Furthermore, inhibition of tumor growth was observed in the xenograft model. In clinical cUC cases, neoplastic urothelium showed significant deacetylation of histones compared to the normal control, where lower histone acetylation levels were associated with a poor prognosis. In conclusion, the therapeutic potential of vorinostat was demonstrated in cUC. Histone deacetylation may be related to cUC tumor progression.

A Fibromyxoid Stromal Response is Associated with Muscle Invasion in Canine Urothelial Carcinoma

Canine urothelial carcinoma (UC) is the most common type of cancer of the lower urinary tract and tends to affect elderly neutered female dogs, with a high predisposition for Scottish terriers. Tumour stroma, inflammation and necrosis are poorly characterized in canine UC and their role as prognostic factors is unknown. The aims of this study were to (1) assess histologically 381 canine UCs, with emphasis on myxoid tumour stroma, inflammation and necrosis and (2) assess possible associations between these features and the available epidemiological data as well as bladder wall muscle invasion. In 103 of 381 (27%) cases, the stroma was mixed collagenous and myxoid (fibromyxoid), which was strongly associated with invasive growth of muscle (P <0.0001). Peritumoural and intratumoural inflammation was present in 308 of 345 (89%) and 287 of 381 (75%) cases, respectively, and was mostly mild and lymphoplasmacytic. One hundred and fifteen of the 381 (30%) cases showed a variable eosinophilic inflammation and 58 of 381 (15%) presented with formations of one or several lymphoid follicles. Twenty-four percent (91 of 381) of cases had tumour necrosis, which was typically mild. In 83 of 91 (91%) cases, the necrosis was comedo-like. Moderate to severe tumour necrosis was associated with the presence of moderate to predominant fibromyxoid tumour stroma (P <0.02). The results of this study indicate that fibromyxoid stroma is common in canine UC and is a strong indicator for invasive growth of muscle, which is consistent with a poor prognosis. Based on histomorphology, tumour necrosis in canine UC is best described as comedonecrosis.

Expression of apoptosis inhibitor of macrophages in tissue macrophages, leukocytes and vascular endothelial cells of dogs

Apoptosis inhibitor of macrophages (AIM) is a protein which plays important roles in controlling the immune response and inflammation in human and mice. In dogs, AIM is reported to be expressed in cancerated macrophages and regulate the survival of these tumor cells. In this study, to elucidate the physiological expression pattern of AIM in dogs, systemic expression and distribution of AIM of dogs were investigated. Mature healthy Beagles were used. Various tissues, peripheral blood cells, and bone marrow cells of normal dogs were collected for in situ hybridization, real-time RT-PCR, and immunohistochemistry. AIM mRNA and protein were expressed in tissue macrophages of the spleen, liver, lungs, and lymph nodes, but not in the microglia of the cerebrum. Proximal tubules in the kidney also expressed AIM protein. Monocytes and B lymphocytes in circulating blood and a part of microvasculature endothelial cells showed AIM expression at both the mRNA and protein levels. In the bone marrow, early-stage monocyte progenitor-like cells expressed AIM mRNA and protein. These results clarified that AIM is expressed in more cell types than previously reported in human and mice. These data spread the possibility of AIM physiological functions and implies the relationship of AIM to the maturation of macrophage-strain cells in dogs and other species.

Association of macrophage and lymphocyte infiltration with outcome in canine osteosarcoma

Immunotherapeutic strategies have shown promise for the treatment of canine osteosarcoma (cOSA). Very little is known about the immune microenvironment within cOSA, however, limiting our ability to identify potential immune targets and biomarkers of therapeutic response. We therefore prospectively assessed the disease-free interval (DFI) and overall survival time (ST) of 30 dogs with cOSA treated with amputation and six doses of adjuvant carboplatin. We then quantified lymphocytic (CD3+, FOXP3+) and macrophage (CD204+) infiltrates within the primary tumours of this cohort using immunohistochemistry, and evaluated their association with outcome. Overall, the median DFI and ST were 392 and 455 days, respectively. The median number of CD3+ and FOXP3+ infiltrates were 45.8 cells/mm² (4.6-607.6 cells/mm² ) and 8.5 mm² (0-163.1 cells/mm² ), respectively. The median area of CD204+ macrophages was 4.7% (1.3%-23.3%), and dogs with tumours containing greater than 4.7% CD204+ macrophages experienced a significantly longer DFI (P = 0.016). Interestingly, a significantly lower percentage of CD204+ macrophages was detected in cOSA arising from the proximal humerus compared to other appendicular bone locations (P = 0.016). Lymphocytic infiltrates did not appear to correlate with outcome in cOSA. Overall, our findings suggest that macrophages may play a role in inhibiting cOSA progression, as has been suggested in human osteosarcoma.