Clonality testing in the lymph nodes from dogs with lymphadenomegaly due to Leishmania infantum infection

Clinical Use of Molecular Biomarkers in Canine and Feline Oncology: Current and Future

Molecular biomarkers are central to personalised medicine for human cancer patients. It is gaining traction as part of standard veterinary clinical practice for dogs and cats with cancer. Molecular biomarkers can be somatic or germline genomic alterations and can be ascertained from tissues or body fluids using various techniques. This review discusses how these genomic alterations can be determined and the findings used in clinical settings as diagnostic, prognostic, predictive, and screening biomarkers. We showcase the somatic and germline genomic alterations currently available to date for testing dogs and cats in a clinical setting, discussing their utility in each biomarker class. We also look at some emerging molecular biomarkers that are promising for clinical use. Finally, we discuss the hurdles that need to be overcome in going 'bench to bedside', i.e., the translation from discovery of genomic alterations to adoption by veterinary clinicians. As we understand more of the genomics underlying canine and feline tumours, molecular biomarkers will undoubtedly become a mainstay in delivering precision veterinary care to dogs and cats with cancer.

Mass spectrometric-based assessment of the serum kappa to lambda immunoglobulin light chain ratio (κ:λ) in dogs with immunoglobulin secretory diseases

The ratio of κ light chains to λ light chains (κ:λ) in serum is used as a biomarker of immunoglobulin secreting neoplasia in humans but has not been evaluated in dogs. A mass-spectrometry based method for determining the canine serum κ:λ was developed and used to evaluate samples from control dogs, dogs with an infectious aetiology, dogs with secretory plasma cell tumours (sPCT) and dogs with non-secretory B cell neoplasia. A human-targeted immunoturbidometric κ:λ assay and immunofixation using antisera targeting human κ light chain or λ light chain was also performed on all samples. Using whole serum samples, the MS-based κ:λ method identified 5 sPCT as κ-predominant (mean κ:λ = 3.307) and 5 sPCT as λ-predominant (mean κ:λ = 0.023) and documented differences between these groups and all other groups (p < 0.05 for all). The infectious aetiology group had a lower mean κ:λ ratio (mean κ:λ = 0.069) than control samples (mean κ:λ = 0.103, p = 0.035). Similar results were obtained when samples were enriched for proteins between 10 and 50 kDa using size exclusion chromatography, except for the statistical difference between the control and infectious aetiology group. All λ-predominant cases had only anti-human λ light chain labelling by immunofixation. Three κ-predominant cases had only anti-human κ-light chain labelling and the remaining two cases did not label with either antisera by immunofixation. The immunoturbidometric method had high analytical CV% (λ light chain CV = 13%, κ light chain CV = 50%), was unable to measure light chains in 20.5% of samples and did not distinguish groups. The data suggests that the human-targeted immunoturbidometric method would not be diagnostically useful and that the MS-derived serum κ:λ may be a useful biomarker of canine immunoglobulin secretory neoplasia which may have the ability to distinguish neoplasia from infectious causes of immunoglobulin secretion.

A clonality assay in canine B cell tumors targeting the immunoglobulin light chain lambda locus

Clonality assays for antigen receptor rearrangement have been used as adjunct examinations of lymphoproliferative diseases. These assays have been useful for differentiation between inflammation and clonal expansion of lymphocytes. Whereas the immunoglobulin heavy chain (IGH) and immunoglobulin light chain kappa (IGK) loci have been targeted in canine clonality assays previously, the immunoglobulin light chain lambda gene (IGL) locus has not yet been investigated. This study aimed to evaluate the usefulness of clonality assays in dogs using IGL. Canine diffuse large B cell lymphomas (DLBCL), cutaneous plasmacytomas, and pathologically diagnosed lymph nodes without lymphoma, were used in this study. Genomic DNA was extracted from formalin-fixed paraffin embedded sections. Sequences of IGLV and IGLJ were obtained from the ImMunoGeneTics database. Several primers against IGLVs and IGLJs were designed in the regions showing homology, by alignment of the gene segments. Products of polymerase chain reaction were analyzed on a capillary electrophoresis. In total, 20 of 23 cases of DLBCL showed clonality (87.0 %), whereas 8 of 30 cutaneous plasmacytomas were clonal (26.7 %). One of 23 lymph nodes without lymphoma showed clonality, thus the specificity was 95.7 %. These data indicate that the IGL locus could be a target for canine clonality assays and that the sensitivity of IGL-based clonality assays in cutaneous plasmacytomas was lower than that in DLBCL.

Evaluation of clonality from multiple anatomic sites in canine epitheliotropic T cell lymphoma

BACKGROUND

Canine epitheliotropic cutaneous T-cell lymphoma (eCTCL) is thought to represent a disease homologue to human mycosis fungoides (MF). In human MF, neoplastic cells are phenotypically consistent with resident effector memory T cells, a population that remains for an extended period within tissue without circulating. Dogs with eCTCL often present with lesions in multiple locations, raising the question of whether the neoplasm is of the same T-cell subpopulation or not.

OBJECTIVES

To characterize the antigen receptor gene rearrangements of lymphocytes from skin and blood of dogs with eCTCL to determine if neoplastic clones are identical.

ANIMALS

Fourteen dogs with eCTCL.

MATERIALS AND METHODS

Histological and immunohistochemical examination, and PCR for antigen receptor rearrangement (PARR) for T-cell receptor gamma (TRG) performed on multiple cutaneous biopsy samples and blood.

RESULTS

All skin biopsies contained cluster of differentiation (CD)3-positive neoplastic lymphocytes. Within individual dogs, all skin biopsies revealed identical TRG clonality profiles, suggesting that the same neoplastic clone was present in all sites. In the blood, a matching clone was found in six of 14 dogs, a unique clone was observed in nine of 14 dogs, and no clone was detected in two of 14 dogs.

CONCLUSIONS

These findings show that canine eCTCL lesions in multiple locations harbour the same neoplastic clone, neoplastic lymphocytes do not remain fixed to the skin and instead can circulate via blood, differing clones can be identified in skin versus blood, and circulating neoplastic cells can be detected without lymphocytosis.

Doing more with less: multiple uses of a single slide in veterinary cytology. A practical approach

Veterinary cytology faced a remarkable evolution in the last 15 years, in part due to increase recognition of the advantages of the cytology by veterinary clinicians. Simultaneously, there has been a growing awareness by the owners about the importance of a complete diagnostic workup aimed at defining a proper treatment protocol. With the extended use of cytology, challenging diagnostic cases are more frequent, and more clinically useful answers are requested. In this scenario, the use of cytology specimens to perform ancillary techniques is a valid approach. Rather than being simply archived, cytology slides can be a valuable source and a good platform to carry out cytochemistry, immunocytochemistry, and molecular techniques. Therefore, several diagnostic techniques can be applied in tiny samples, thus following the "doing more with less" principle. The aim of this approach is to refine the cytologic diagnosis and provide additional prognostic and therapeutic information. Herein, we detailed this principle in veterinary cytology and reviewed the use of cytology specimens for ancillary techniques as a single procedure, i.e., using the whole slide, or multiple procedures, i.e., multiple procedures applied in the same slide.

A newly established canine NK-type cell line and its cytotoxic properties

We established a canine natural killer (NK)-type cell line called CNK-89 derived from a dog with NK cell neoplasia. Immunophenotyping analysis showed positive staining for CD5, CD8, CD45, CD56, CD79a and NKp46, while negative for CD3, CD4, CD14, CD20, CD21, CD34, Thy1, IgG, IgM and MHCII. Polymerase chain reaction analysis revealed the presence of CD56, NKG2D, NKp30, NKp44, NKp46 and perforin, but the absence of CD16, Ly49 and granzyme B mRNA. Treating CNK-89 cells with IL-2 did not change the expression of activating receptors, TNFα and IFNγ secretion and cytotoxic activity, however, treatment with IL-12 alone or in combinations with IL-15, IL-18 and IL-21 caused an increase in granzyme B and CD16 mRNA, IFNγ secretion and cytotoxic properties of the CNK-89 cell line.

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.