Chemotherapy and remission status do not alter pre-existing innate immune dysfunction in dogs with lymphoma

Bacterial urinary tract infection and subclinical bacteriuria in dogs receiving antineoplastic chemotherapy

Background

Immunosuppressive treatment with glucocorticoids and cyclosporine increases the risk for positive urine cultures (PUCs) in dogs.

Objective

To investigate the prevalence and incidence of PUC in dogs diagnosed with cancer and treated with antineoplastic chemotherapy while distinguishing between subclinical bacteriuria (SB) and urinary tract infection (UTI).

Animals

Forty‐six client‐owned dogs with nonurogenital cancer treated with antineoplastic chemotherapy.

Methods

Prospective observational longitudinal clinical study. Dogs in which a urine culture was performed before the start of and at least once during antineoplastic chemotherapy were included. A McNemar's test was used to investigate if the prevalence of PUC increased during antineoplastic chemotherapy. Positive urine cultures were categorized into SB and UTI and multiple PUCs from the same dog and category were grouped together as 1 episode of PUC.

Results

Urine culture was positive in 21/185 urine samples in 8/46 dogs. Antineoplastic chemotherapy did not influence the prevalence of PUC (P = 1.00), which was 11% (5/46 dogs; 95% confidence interval: 5‐23%) before the start of and 13% (6/46 dogs; 95% confidence interval: 6‐26%) during antineoplastic chemotherapy. Eight dogs had 10 episodes of PUC; 7/10 episodes were classified as SB, and in 3/10 episodes UTI (chronic prostatitis, prostatic abscess, and emphysematous cystitis) was diagnosed. Escherichia coli was the most common pathogen, isolated in 9/10 episodes.

Conclusions and Clinical Importance

We did not find evidence that antineoplastic chemotherapy is a major predisposing factor for the development of PUC. Most dogs with PUC had SB.

Canine lymphoma and vector-borne diseases: Molecular and serological evaluation of a possible complicity

Lymphoma is the most common haematological malignancy in dogs and its aetiology is largely unknown. The presence of canine vector-borne agents (CVBD) in lymphoma tissues has been described and its causative effects questioned. We intended to evaluate the presence and extent of Leishmania infantum, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae infection in dogs with lymphoma. Sixty-one dogs, living in the Lisbon metropolitan area, with a diagnosis of lymphoma were enrolled. Immunofluorescence assays were used to detect serum IgG's. The presence of DNA from CVBD agents in tumour tissue was assessed by PCR. All dogs tested negative for B. henselae, A. phagocytophilum and E. canis by both serology and PCR. Regarding L. infantum, 8.2% (n = 5) of the dogs had a positive serologic result. L. infantum DNA was detected in two samples of diffuse large B-cell lymphoma (DLBCL). These results show an increased, but not significant, seropositivity (8.2% vs 7.9%) and molecular detection (3.3% vs 1.2%) for L. infantum in dogs with lymphoma, when compared to the reported canine population in the same geographical area. We could not identify an association between lymphoma and E. canis, A. phagocytophilum, B. henselae or Leishmania infantum infection in the studied population. Nevertheless, further studies, following dogs trough their CVBD disease evolution, are worthwhile and may help clarify a possible role of CVBD agents in lymphomagenesis.

Transportation and Routine Veterinary Interventions Alter Immune Function in the Dog

Rapid activation of the hypothalamic pituitary adrenal axis and the sympathetic nervous system are hallmarks of the acute stress response and these systems interact with the immune system by signaling though glucocorticoid and adrenergic receptors on immune cells. There is limited information about the effect of these physiologic responses on immunologic parameters of pet dogs enrolled in clinical studies. The objective of this study was to evaluate how travel, instrumentation, and hospitalization alter immunologic parameters in pet dogs. Blood was collected from healthy dogs in a home environment and from healthy dogs at the time of presentation to the hospital and after instrumentation and 24 hours of hospitalization. We found that lipopolysaccharide (LPS)-induced downregulation of toll like receptor 4 (TLR4) was blunted in dogs exposed to stress. Neutrophil and monocyte major histocompatibility complex class II (MHCII) expression increased after transportation to the veterinary hospital but then became similar to that of the control dogs at the end of hospitalization. Peripheral blood mononuclear cell cytotoxicity function was blunted in dogs exposed to the stress of transportation as well as hospitalization. Neutrophil apoptosis was greater in dogs exposed to stress compared to controls although this effect significantly decreased after hospitalization stress. Conversely, stress did not alter induced or spontaneous cytokine production from leukocytes, neutrophil or monocyte expression of TLR4, LPS-induced downregulation of monocyte TLR4, LPS-induced neutrophil and monocyte expression of MHCII or peripheral blood lymphocyte phenotype. Transportation and instrumentation/hospitalization stress should be considered when interpreting immunologic studies in pet dogs.

Vincristine, carboplatin and cisplatin increase oxidative burst induced by PAF in canine neutrophils

Myelosupression resulting from chemotherapy has been widely described in veterinary medicine; however, there is limited information relating to alterations in neutrophil function after chemotherapy in dogs with cancer. The aim of this study was to determine the non-proliferative effects of vincristine, carboplatin, and cisplatin on canine neutrophils by evaluating activation of oxidative and non-oxidative responses. Neutrophils were isolated from venous blood. Levels of reactive oxygen species (ROS) and metalloproteinase 9 (MMP-9) were measured in vitro during neutrophil exposure to these chemotherapeutic agents for 15 min followed by stimulation with platelet activating factor (PAF). ROS production was detected via luminescence, and MMP- 9 liberation was determined by zymography. The chemotherapeutic agents caused an increase in PAF-induced ROS production, but no change in the non-oxidative response was observed. These results suggest that these chemotherapeutic agents may act as priming agents by increasing the oxidative response. These effects could be beneficial for dogs with cancer by supporting their immune systems; however, excessive ROS liberation has been associated with inflammation, neutrophil-mediated cell injury, carcinogenesis, and metastasis. Clinical studies are necessary to evaluate the significance of these findings.

Imatinib enhances the anti-tumour effect of doxorubicin in canine B-cell lymphoma cell line

Canine lymphoma is one of the most common malignant tumours occurring in dogs and has a high incidence worldwide. Despite advances in cancer prevention, the treatment of neoplastic diseases still requires improvement. Some cancer cells may resist the effect of chemotherapeutic agents by up-regulating drug transporters leading to increased drug efflux, resulting in intrinsic or acquired drug resistance, which is a mechanism commonly seen in doxorubicin-resistant tumour cells. In this study, canine B-cell lymphoma cell line CLBL1-8.0, a doxorubicin-resistant B cell lymphoma cell line derived from CLBL-1 by increasing the doxorubicin concentration during culturing, exhibited high expression of P-glycoprotein (P-gp, ATP-binding cassette sub-family B member 1 [ABCB1]). These proteins are commonly involved in cancer cell resistance to doxorubicin. Imatinib, a tyrosine kinase inhibitor significantly potentiated the sensitivity of doxorubicin in P-gp-overexpressing doxorubicin-resistant cells. Moreover, a combination of these two drugs may increase the retention of doxorubicin by decreasing the efflux of doxorubicin without affecting P-gp protein overexpression. In conclusion, imatinib reversed doxorubicin resistance by decreasing drug efflux in P-gp-overexpressing doxorubicin-resistant canine lymphoma cells. These results suggest that combining doxorubicin, one of the most widely used chemotherapeutic drugs in the treatment of canine lymphoma, with imatinib might potentially overcome doxorubicin resistance in a clinical setting.

Canine multicentric lymphoma exhibits systemic and intratumoral cytokine dysregulation

Non-Hodgkin Lymphoma (NHL) is among the most common neoplasias in dogs and humans. Owing to remarkable similarities with its human counterpart, the canine lymphoma (cNHL) model has been proposed as a powerful framework for rapid and clinically relevant translation of novel immunotherapies. However, the establishment of cNHL as a predictive preclinical model has been hampered by the limited characterization of the canine immune system. Cytokines are key players of the interaction between tumor and its microenvironment. In human NHL, multiple cytokines have been linked to the development of lymphoma and are relevant biomarkers for treatment response and prognosis. In contrast, few studies have investigated cytokines in cNHL. Within this context, this study aimed to investigate cytokine regulation in cNHL. A multicentric cNHL biobank was successfully constructed. Cytokine mRNA profiles in tumor tissue and circulating PBMC were analyzed by qRT-PCR and compared to a healthy control group. Specific primers were used to evaluate Th1, Th2 and Th17 responses. Systemic cytokine concentrations were measured using a commercial canine multiplex assay which included IL-2, IL6, IL-10 and TNF-α, and compared to a healthy control group. Our results demonstrated a dysregulation of cytokine mRNA expression, representative of the tumor microenvironment and systemic response in cNHL. Intratumoral cytokine response revealed a significant downregulation of humoral and Th1 responses. The systemic response demonstrated a distinct mRNA pattern, however immunosuppression also prevailed. Cytokine serum quantification showed a significant increase of IL-10 concentration in cNHL. Significant differences in hematological parameters were described and a correlation between IL-6 protein serum levels and neutrophil count was shown. Finally, data analysis demonstrated that baseline pretreatment IFN-γ tissue mRNA levels were correlated to survival outcome, predicting a favorable response to chemotherapy. Altogether, these results revealed that cNHL presents a local and systemic dysregulation in cytokine response. By confirming and extending previous research, our work contributed for the evaluation of potential cytokine candidates for diagnostic, prognostic purposes and therapeutic intervention, therefore adding value to comparative oncology.

Dogs with osteosarcoma have altered pro- and anti-inflammatory cytokine profiles

Background

Current advances in immunotherapy are an exciting area of study in canine osteosarcoma (OSA). The objective of this study was to determine the immune response in dogs with osteosarcoma by measuring stimulated leukocyte production of tumor necrosis factor (TNF), interleukin (IL)‐6, IL‐10 and TNF and IL‐6 to IL‐10 ratios.

Methods

Whole blood was collected from dogs with osteosarcoma receiving non‐steroidal anti‐inflammatory drugs (NSAIDs, n = 11), dogs with osteosarcoma not receiving NSAIDs (n = 14) and healthy dogs (n = 5).

Results

No difference in TNF production was found among healthy and OSA dogs regardless of NSAID administration following stimulation with lipopolysaccharide (LPS) (p = .410), lipoteichoic acid (LTA) (p = .693) or PBS (p = .120). Leukocyte IL‐6 production was greater in all dogs with OSA after stimulation with LPS (p = .015), LTA (p = .014) and PBS (p = .034) with no difference between OSA dogs receiving NSAIDs and those not. No differences in IL‐10 were found among healthy controls and dogs with OSA regardless of NSAID use. There was no difference among groups for LPS‐stimulated TNF to IL‐10 ratios (p = .407). For LTA‐stimulated leukocytes, the TNF to IL‐10 ratio was lower in dogs with OSA than in healthy dogs (p = .031) with no difference between OSA NSAID dogs compared to OSA non‐NSAID dogs (p = .059). No differences were found in LPS (p = .310)‐ or LTA (p = .265)‐stimulated leukocyte IL‐6 to IL‐10 production ratios among groups.

Conclusions

Dogs with osteosarcoma have an altered pro‐ and anti‐inflammatory immunologic profile compared to healthy dogs regardless of NSAID use. Further study is indicated to determine the potential prognostic and therapeutic implications of these findings.

The leukocytes of dogs with osteosarcoma had altered cytokine production in response to pathogen associated molecular pattern motifs compared to healthy dogs with increased IL‐6 production following LPS and LTA‐stimulation and decreased TNF‐to‐IL‐10 ratios following LTA‐stimulation. Future investigations should monitor leukocyte function through a defined treatment protocol and determine the prognostic significance and potential therapeutic targeting of these changes. These factors, with other immunologic parameters, should also be considered when investigating immunotherapy as potential predictive and prognostic markers.

Effects of calcitriol on phagocytic function, toll-like receptor 4 expression, and cytokine production of canine leukocytes

OBJECTIVE To determine the in vitro effects of calcitriol on indicators of immune system function in blood samples collected from healthy dogs. SAMPLE Blood samples from 8 healthy adult dogs. PROCEDURES Blood samples were incubated with calcitriol (10^-7M) or control substance for 24 hours. Afterward, lipopolysaccharide (LPS)-, lipoteichoic acid (LTA)-, and N-acetylmuramyl-l-alanyl-d-isoglutamine hydrate (MDP)-stimulated leukocyte production of tumor necrosis factor (TNF) and interleukin-10 (IL10) were measured with a canine-specific multiplex assay. Phagocytosis of opsonized Escherichia coli and leukocyte expression of constitutive toll-like receptor 4 (TLR4) were evaluated via flow cytometry. Blood samples from 3 dogs were used to create a concentration-response curve to evaluate whether the observed cytokine modulation was concentration dependent. RESULTS Incubation of canine blood samples with calcitriol resulted in significant decreases in LPS-, LTA-, and MDP-stimulated leukocyte production of TNF but not IL10. Blunting of TNF production was concentration dependent. Leukocyte calcitriol exposure had no significant effect on phagocytosis and TLR4 expression. CONCLUSIONS AND CLINICAL RELEVANCE These data indicated that calcitriol induced an anti-inflammatory shift in canine leukocytes exposed to LPS, LTA, and MDP in vitro, without altering phagocytosis or TLR4 expression. Thus, calcitriol could represent a novel candidate immunomodulatory treatment for dogs.

Immune response to C. novyi-NT immunotherapy

Clostridium novyi-NT (CVN-NT) spores germinate in hypoxic regions of tumors and have successfully cured induced neoplasia in mouse models and resulted in objective tumor responses in naturally developing neoplasia in the dog. The objective of this pilot, descriptive, prospective, clinical investigation, was to evaluate and describe the immune response to CNV-NT spores to better understand which immune pathways might play a role in the response to this bacteriolytic immunotherapy. Intratumoral injection of CNV-NT spores result in increased phagocytosis and NK cell-like function after treatment. Intravenous injection of CNV-NT spores resulted in increased LPS-induced TNF-α production, LTA-induced IL-10 production and NK cell-like function post-treatment. Increased NK cell-like function was sustained to 28 (intratumoral) or 56 (intravenous) days post-treatment, and increased phagocytic function was sustained to 28 days post-treatment suggesting that CNV-NT spores induce longer-term immune cell function changes. Future investigations evaluating long-term immune system changes and associations between immune function and tumor remission rates should include evaluation of these pathways.

Identification of immunologic and clinical characteristics that predict inflammatory response to C. Novyi-NT bacteriolytic immunotherapy

BACKGROUND

Clostridium novyi-NT (CNV-NT), has shown promise as a bacterolytic therapy for solid tumors in mouse models and in dogs with naturally developing neoplasia. Factors that impact the immunologic response to therapy are largely unknown. The goal of this pilot study was to determine if plasma immune biomarkers, immune cell function, peripheral blood cytological composition and tumor characteristics including evaluation of a PET imaging surrogate of tumor tissue hypoxia could predict which dogs with naturally developing naïve neoplasia would develop an inflammatory response to CNV-NT.

RESULTS

Dogs that developed an inflammatory response to CNV-NT had a higher heart rate, larger gross tumor volume, greater tumor [⁶⁴Cu]ATSM SUV_Max, increased constitutive leukocyte IL-10 production, more robust NK cell-like function and greater peripheral blood lymphocyte counts compared to dogs that did not develop an inflammatory response to CNV-NT. Of these, unstimulated leukocyte IL-10 production, heart rate, and gross tumor volume appeared to be the best predictors of which dogs will develop an inflammatory response to CNV-NT.

CONCLUSIONS

Development of inflammation in response to CNV-NT is best predicted by pretreatment unstimulated leukocyte IL-10 production, heart rate, and gross tumor volume.

Immune Function in Critically Ill Dogs

Background

People with critical illness (CI) commonly develop various forms of immune dysfunction, however, there is limited information concerning immune dysfunction in dogs with CI.

Hypothesis

The immune response in CI dogs differs from that of healthy dogs.

Animals

Immunologic variables were compared between 14 dogs with CI, defined as APPLE_fast score of >20 points, admitted to the University of Missouri Veterinary Health Center Small Animal Clinic Intensive Care Unit and healthy controls (n = 15).

Methods

Cohort study evaluating constitutive and lipopolysaccharide (LPS)‐stimulated TNF‐α, IL‐6, and IL‐10 production, phagocytosis of opsonized E. coli and respiratory burst capacity after opsonized E. coli or phorbol 12‐myristate 13‐acetate (PMA) stimulation, peripheral blood lymphocyte phenotype, and monocyte expressions of HLA‐DR and TLR‐4.

Results

Lipopolysaccharide‐stimulated leukocyte TNF‐α (median, Q1, Q3; CI, 49, 49, 120; control, 655, 446, 1174 pg/mL; P = < 0.001), IL‐6 (median, Q1, Q3; CI, 49, 49, 64; control, 100, 49, 166 pg/mL; P = 0.029), and IL‐10 (CI, 49, 49, 56; control, 96, 49, 203 pg/mL; P = 0.014) production and both E. coli (median, Q1, Q3; CI, 60.5, 43, 88.5; control, 86.6, 81, 89.2%; P = 0.047) and PMA (CI, 40, 11.7, 70; control, 93, 83, 97.6%; P = < 0.001)‐stimulated respiratory burst capacity significantly decreased in CI dogs. Percentage of monocytes expressing TLR‐4 greater in the CI dogs (median, Q1, Q3; CI, 46.9, 24.3, 64.2; control, 16.4, 9.4, 26.2%; P = 0.005).

Conclusion

These findings suggest dogs with CI develop immune system alterations that result in reduced respiratory burst function and cytokine production despite upregulation of TLR‐4.

Factors Which Influence Owners When Deciding to Use Chemotherapy in Terminally Ill Pets

Chemotherapy is a commonly integrated treatment option within human and animal oncology regimes. Limited research has investigated pet owners' treatment decision-making in animals diagnosed with malignant neoplasia. Dog and cat owners were asked to complete an online questionnaire to elucidate factors which are key to the decision making process. Seventy-eight respondents completed the questionnaire in full. Fifty-eight percent of pet owners would not elect to treat pets with chemotherapy due to the negative impact of the associated side effects. Seventytwo percent of respondents over estimated pet survival time post chemotherapy, indicating a general perception that it would lead to remission or a cure. Vomiting was considered an acceptable side effect but inappetence, weight loss and depression were considered unacceptable. Owners did expect animals' to be less active, sleep more and play less, but common side effects were not rated as acceptable despite the potential benefits of chemotherapy. Based on the results, veterinary teams involved with oncology consultations should establish if clients have prior experience of cancer treatments and their expectations of survival time. Quality of life assessments should also be implemented during initial oncology consultations and conducted regularly during chemotherapy courses to inform client decision making and to safe guard animal welfare.

Comparison of serum cytokine levels between dogs with multicentric lymphoma and healthy dogs

In humans, multiple cytokines have been linked to the development of lymphoma, and are relevant biomarkers for response to chemotherapy and prognosis. In contrast, only a few circulating cytokines have been studied in dogs with lymphoma. We prospectively enrolled thirty-one dogs newly diagnosed with multicentric lymphoma. Immunophenotype was determined by flow cytometry in all dogs, separating them into 2 subgroups: B cell lymphoma (n=21) and T cell lymphoma (n=10). Nineteen healthy dogs were enrolled in the control group. Circulating cytokine concentrations were measured using a commercial canine multiplex magnetic bead-based assay which included Interleukin-2 (IL-2), IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), Tumor Necrosis Factor-α (TNF-α), Interferon γ (IFN-γ), IFN-γ induced Protein-10 (IP-10), Keratinocyte Chemoattractant-like (KC-like), and Monocyte Chemoattractant Protein-1 (MCP-1). The serum levels of each cytokine were first compared between the lymphoma and control groups, and then between the B cell lymphoma, T cell lymphoma, and control groups. There was no significant difference between the lymphoma and healthy control groups regarding sex, age and weight. MCP-1, IL-6, and IL-10 were significantly higher in dogs with lymphoma compared to healthy dogs (p<0.01, p=0.01 and p=0.03, respectively). MCP-1 and IL-10 were significantly higher in the B cell lymphoma group than in the healthy group (p=0.01, p=0.01, respectively). MCP-1 and IL-6 levels were significantly higher in the T cell lymphoma group than in the healthy group (p=0.02, p<0.01, respectively). IL-6 was significantly higher in the T cell lymphoma group than in the B cell lymphoma group (p=0.03). Significant differences among the groups were found for IL-15 and KC-like, but they were affected by age and/or sex. There were no significant differences in serum IL-2, IL-7, IL-8, IL-18, GM-CSF, TNF-α, IFN-γ, and IP-10 between any of the groups. Significant differences in red blood cell, white blood cell, neutrophil, lymphocyte and monocyte counts were also found between the different groups of dogs. Our data showed different serum cytokine and peripheral blood cell profiles between dogs with lymphoma and healthy dogs, and between dogs with B cell and T cell lymphoma. Further study is necessary to investigate the role of these cytokines in lymphoma pathogenesis, response to treatment, and prognosis, and the influence of age, sex and blood cell counts on their expression.