Characterizing circulating nucleosomes in the plasma of dogs with lymphoma

Abstract

Background Nucleosomes consist of DNA wrapped around a histone octamer core like beads on a string so that DNA can be condensed as chromatin into chromosomes. Diseases such as cancer or inflammation lead to cell death where chromatin is fragmentated and released as mononucleosomes into the blood. The Nu.Q™ H3.1 assay measures total nucleosome concentration in plasma of humans and has been used to detect and identify cancer even at early stages. The objectives of this study were to determine if nucleosome levels could be used to distinguish between healthy dogs and dogs with various stages of lymphoma (LSA) using the Nu.Q™ H3.1 assay. A total of 126 dogs diagnosed with LSA and 134 healthy controls were recruited for this study. Plasma was collected from each dog and stored in K2-EDTA tubes. The LSA patient samples were recruited from TAMU or purchased from various biobanks. All control cases were recruited from TAMU. Results Dogs with LSA had an approximately 7-fold increase in their plasma nucleosome concentrations compared to controls (AUC 87.8%). Nucleosome concentrations increased with cancer stage and dogs with B cell lymphomas had significantly higher nucleosome concentrations than dogs with T cell lymphomas. Conclusions The Nu.Q™ H3.1 assay was able to reliably detect elevated nucleosome concentrations in the plasma of dogs with LSA. Furthermore, it appears that nucleosomes are useful for differentiating cancer from healthy individuals in canines.

Evaluation of plasma nucleosome concentrations in dogs with a variety of common cancers and in healthy dogs

“…Nucleosome levels were evaluated in plasma samples from patients with seven of the most common canine cancers. The dogs with the most frequent elevations in plasma nucleosome concentrations were dogs with hemangiosarcoma and lymphoma, consistent with previous publications [ 20 , 21 ]. Other cases with frequent elevations in plasma nucleosome concentrations include those with histiocytic sarcoma and oral malignant melanoma.…”

“…Detailed evaluations of plasma nucleosome concentrations in dogs with lymphoma and hemangiosarcoma by stage, location or phenotype have been described elsewhere [ 20 , 21 ]. For the cases with melanoma there were two main groups.…”

“…A detailed characterization of the participants has been included in the results section. The lymphoma and hemangiosarcoma cases were previously described in two publications from 2021 [ 20 , 21 ]. These cases were included here in order to generate a broad AUC and sensitivity and specificity of this assay for the most common canine cancers.…”

Serial analysis of blood biomarker concentrations in dogs with pneumonia, septic peritonitis, and pyometra

“…The concentrations of cfDNA, nucleosomes and HMGB1 were measured as putative NETosis biomarkers, although none is ideal for quantifying NETosis in dogs. 94 Previous studies of dogs with sepsis and systemic inflammation suggest these markers are not discriminatory for sepsis, perhaps because NETosis contributes to disease pathogenesis in IMHA, 95 gastric dilatation‐volvulus (GDV) syndrome, 96 cancer, 97 , 98 trauma, 86 , 99 and pancreatitis. 100 Alternatively, these markers may be nonspecific for NETosis in dogs through release by necrotic and apoptotic cells.…”

Monitoring plasma nucleosome concentrations to measure disease response and progression in dogs with hematopoietic malignancies

“…In some cases, serum calcium or globulin levels may also be used to monitor for progression and response, however these patients represent the minority of the cases managed. Liquid biopsy or circulating biomarker assays for the diagnosis and treatment monitoring of LSA in canines is an area of active investigation for several groups(2, 3, 4, 5, 6), though currently, there is no commercially available biomarker for treatment or remission monitoring in veterinary oncology.…”