Determining prognosis in canine sepsis by bedside measurement of cell-free DNA and nucleosomes

Prognostic value of red blood cell distribution width to albumin ratio for predicting mortality in adult patients meeting sepsis-3 criteria in intensive care units

BACKGROUND

Patients with sepsis with low albumin levels and high red blood cell distribution width levels have poor prognoses. Red blood cell distribution width to albumin ratio (RAR) has recently attracted attention as an innovative inflammation biomarker. We aimed to explore the association between RAR and the prognosis of patients with sepsis.

METHODS

This retrospective observational study included 402 patients meeting the sepsis-3 standards admitted to Yantai Yuhuangding Hospital's intensive care units (ICUs) between January 2020 and December 2022. The relationship between RAR and mortality in patients with sepsis was examined using regression analysis, Kaplan-Meier analyses, and a receiver operating characteristic curve. Subgroup and sensitivity analyses were conducted to assess the results' robustness.

RESULTS

RAR, when considered as a continuous variable, was a significant independent in-hospital mortality risk factor (adjusted odds ratio [OR]: 1.383; 95% confidence interval [CI]: 1.164-1.645; P < 0.001). When considering RAR as a categorical variable, the ORs (95% CIs) of hospital mortality for quartile 2 (Q2), Q3, and Q4 compared with Q1 were 1.027 (0.413-2.551), 3.632 (1.579-8.354), and 4.175 (1.625-10.729), respectively, P < 0.001. Similar outcomes were observed for 28- and 90-day mortalities.

CONCLUSIONS

RAR may indicate clinical prognosis for patients with sepsis in the ICU, potentially providing a low-cost, easily repeatable, and accessible biomarker for risk categorization for these patients.

Diagnosis of Septic Body Cavity Effusion in Dogs and Cats: Cytology vs. Bacterial Culture

The elective test for the determination of the effusions etiopathogenesis is represented by physico-chemical analysis and cytology. Nevertheless, the bacterial culture and antibiotic sensitivity tests are crucial for setting therapy and for the outcome. This study compared cytology with microbiology in the etiologic diagnosis of exudative body cavity effusions in dogs and cats collected from October 2018 to October 2022. All samples underwent aerobic and anaerobic culture and cytology examination. Bacterial identifications were confirmed using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, whereas cytological samples were blindly evaluated either in May Grunwald-Giemsa (MGG) or Gram-stained samples by two board-certified clinical pathologists. A moderate agreement (κ = 0.454) between cytology and bacterial culture was revealed. The sensitivity of the cytological evaluation in our study ranged from 38.5% to 67.9%, and the specificity ranged from 88.9% to 100%, depending on the type of the effusion, so cytology may not be representative of the etiopathogenesis, whereas bacterial culture can misidentify or fail to isolate the correct pathogen for difficult in vitro growing due to the presence of inhibitory substances or contamination. Cytology and bacterial culture results for exudative body cavity effusions in dogs and cats can be misleading if conducted separately, so these two tests should be performed together to increase diagnostic accuracy.

Noninvasive Blood-Based Cancer Detection in Veterinary Medicine

The past decade has seen incredible advances in blood-based cancer detection in people and in dogs - yet this represents only a glimpse of the benefits these tests can provide to patients. The clinical uses of this technology range from screening asymptomatic individuals for early detection to use as an aid in diagnosis when cancer is suspected, to cancer monitoring both during and after treatment. This article summarizes the benefits of early cancer detection and examines use cases and methods of blood-based cancer detection in dogs, including quantitative, qualitative, and alternative approaches.

Point-of-care and traditional erythrocyte sedimentation rate, point-of-care rheometry, and cell-free DNA concentration in dogs with or without systemic inflammation

RBC aggregation and deformability characteristics are altered by inflammatory, microcirculatory, and hemorheologic disease. These changes can be indirectly evaluated using the erythrocyte sedimentation rate (ESR). Newer point-of-care devices employ syllectometry to evaluate RBC rheology, which can give information beyond the ESR. We evaluated 2 point-of-care rheometers (iSED and MIZAR; Alcor Scientific) in 52 dogs presented to a university teaching hospital. Whole blood samples were analyzed for correlation between the ESR using the Westergren (ESRw) method (measured at 1 h and 24 h) and the predicted ESR using iSED. Plasma fibrinogen and cell-free DNA concentrations were also measured as probable markers of inflammation. The iSED-predicted ESR was positively correlated to the ESRw method at 1 h (r = 0.74; p < 0.001) and 24 h (r = 0.62; p < 0.001). Comparing dogs with or without inflammation (defined as plasma fibrinogen concentration >3.5 g/L [350 mg/dL]), significant differences were seen in the MIZAR parameters of base point, amplitude, integral, and half-time. Median cell-free DNA concentrations were higher in the group of dogs with inflammation (117 [range: 51-266] ng/mL vs. 82.7 [range: 19-206] ng/mL; p = 0.024). The iSED-predicted ESR is a good predictor of the ESRw and was obtained more rapidly. Rheometric parameters measured by MIZAR may be useful in detecting inflammation and monitoring secondary morphologic and functional changes in canine RBCs.

Review of Molecular Technologies for Investigating Canine Cancer

Genetic molecular testing is starting to gain traction as part of standard clinical practice for dogs with cancer due to its multi-faceted benefits, such as potentially being able to provide diagnostic, prognostic and/or therapeutic information. However, the benefits and ultimate success of genomic analysis in the clinical setting are reliant on the robustness of the tools used to generate the results, which continually expand as new technologies are developed. To this end, we review the different materials from which tumour cells, DNA, RNA and the relevant proteins can be isolated and what methods are available for interrogating their molecular profile, including analysis of the genetic alterations (both somatic and germline), transcriptional changes and epigenetic modifications (including DNA methylation/acetylation and microRNAs). We also look to the future and the tools that are currently being developed, such as using artificial intelligence (AI) to identify genetic mutations from histomorphological criteria. In summary, we find that the molecular genetic characterisation of canine neoplasms has made a promising start. As we understand more of the genetics underlying these tumours and more targeted therapies become available, it will no doubt become a mainstay in the delivery of precision veterinary care to dogs with cancer.

Comparison of Nucleosome, Ferritin and LDH Levels in Blood with Clinical Response before and after Electrochemotherapy Combined with IL-12 Gene Electrotransfer for the Treatment of Mast Cell Tumours in Dogs

Electrochemotherapy (ECT) in combination with the gene electrotransfer of interleukin 12 (IL-12 GET) has been successfully used in veterinary medicine for the treatment of mast cell tumours (MCT), but the biomarkers that could predict response to this treatment have not yet been investigated. The aim of this study was to determine the plasma nucleosome and serum ferritin concentrations, as well as the lactate dehydrogenase (LDH) activity, in the serum of treated patients before and one and six months after treatment to evaluate their utility as potential biomarkers that could predict response to the combined treatment. The study was conducted in 48 patients with a total of 86 MCTs that we treated with the combined treatment. The blood samples used for analysing the potential predictive biomarkers were taken before treatment and one and six months after treatment, when the response to treatment was also assessed. The Nu. Q® Vet Cancer Test, the Canine Ferritin ELISA Kit, and the RX Daytona+ automated biochemical analyser were used to analyse the blood samples. The results showed that the plasma nucleosome concentration (before treatment (BT): 32.84 ng/mL (median); one month after treatment (1 M AT): 58.89 ng/mL (median); p = 0.010) and serum LDH activity (BT: 59.75 U/L (median); 1 M AT: 107.5 U/L (median); p = 0.012) increased significantly one month after treatment and that the increase correlated significantly with the presence of a more pronounced local reaction (necrosis, swelling, etc.) at that time point for both markers (nucleosome: BT (necrosis): 21.61 ng/mL (median); 1 M AT (necrosis): 69.92 ng/mL (median), p = 0.030; LDH: BT (necrosis): 54.75 U/L (median); 1 M AT (necrosis): 100.3 U/L (median), p = 0.048). Therefore, both the plasma nucleosome concentration and serum LDH activity could serve as early indicators of the effect of the treatment. In this context, the serum ferritin concentration showed no significant predictive potential for treatment response (p > 0.999 for all comparisons). In conclusion, this study provides some new and important observations on the use of predictive biomarkers in veterinary oncology. Furthermore, it emphasises the need for the continued identification and validation of potential predictive biomarkers in dogs with MCT and other malignancies undergoing ECT treatment in combination with IL-12 GET to ultimately improve treatment outcomes.

The effect of doxycycline on canine neutrophil functions

Doxycycline is a broad-spectrum tetracycline-class antibiotic that is frequently used to treat bacterial infections. Its use has also been described in immune-mediated diseases due to its immunomodulatory properties. The aim of this study was to evaluate the immunomodulatory effect of doxycycline on canine neutrophil functions. Therefore, the release of reactive oxygen species (ROS) and the formation of neutrophil extracellular traps (NETs) were determined after incubation of canine PMNs with doxycycline in three different concentrations (4 µg/mL, 20 µg/mL and 200 µg/mL) for one and three hours, respectively. Additionally, a neutrophil killing assay with a doxycycline-resistant Staphylococcus aureus was performed to determine the bactericidal effect of doxycycline treated PMNs in presence of plasma. Doxycycline significantly diminished the production of ROS. However, doxycycline concentrations of 4 µg/mL and 20 µg/mL significantly induced NETs. A synergistic bacteriostatic effect of PMNs and doxycycline on a doxycycline-resistant Staphylococcus aureus isolate was detectable. However, already PMNs and especially doxycycline alone inhibited the growth. In summary, doxycycline showed a concentration-dependent immunomodulatory property in canine PMNs with a reduced ROS production and increased NET-induction. This immunomodulatory effect resulted in a slightly increased elimination of a doxycycline-resistant Staphylococcus aureus by the doxycycline plasma concentrations achieved in dogs.

Visualizing neutrophil extracellular traps in septic equine synovial and peritoneal fluid samples using immunofluorescence microscopy

Septic synovitis and peritonitis are routinely diagnosed in horses based on clinical examination findings and laboratory assessment of synoviocentesis and abdominocentesis samples, respectively. Diagnosis is difficult in some cases because of an overlap in laboratory results for septic and non-septic inflammation. Neutrophil extracellular trap (NET) formation is part of the innate immune response against pathogens. Identifying and quantifying NETs, which have not been explored in clinical samples from horses with septic synovitis and peritonitis, to our knowledge, may be helpful in detecting infectious processes. Our main objective was to determine whether NETs could be visualized in septic equine synovial and peritoneal fluid cytology samples using immunofluorescence with antibodies against citrullinated histone H3 (Cit-H3) and myeloperoxidase (MPO). We analyzed 9 synovial and 4 peritoneal fluid samples. NET percentages were quantified using a simple counting technique, which is suitable for high-quality, well-preserved, and stained cytospin smears. NETs were evident in all septic samples and were absent in a non-septic sample; NETs were better visualized with Cit-H3 than with MPO immunolabeling. Overall, we believe that there is the potential for NETs and associated markers to be used to investigate and understand septic inflammation in horses.

Prognostic impact of blood urea nitrogen to albumin ratio on patients with sepsis: a retrospective cohort study

To investigate the ability of the ratio of blood urea nitrogen (BUN) to serum albumin ratio (BAR) in patients with sepsis in intensive care units (ICUs) to predict the prognosis of short-and long-term death. Data are from the Marketplace for Intensive Care Medical Information IV (MIMIC-IV v2.0) database for patients with sepsis as defined by SEPSIS-3. The primary outcome was 30-day mortality and the secondary outcome was 360-day mortality. Kaplan-Meier (KM) survival curves were plotted to describe differences in BAR mortality in different subgroups and area under the curve (AUC) analysis was performed to compare the predictive value of sequential organ failure assessment (SOFA), BAR, blood urea nitrogen (BUN) and albumin. Multivariate Cox regression models and subgroup analysis were used to determine the correlation between BAR and 30-day mortality and 360-day mortality. A total of 7656 eligible patients were enrolled in the study with a median BAR of 8.0 mg/g, including 3837 in the ≤ 8.0 group and 3819 in the BAR > 8.0 group, with 30-day mortality rates of 19.1% and 38.2% (P < 0.001) and 360-day mortality rates of 31.1% and 55.6% (P < 0.001). Multivariate Cox regression models showed an increased risk of death for 30-day mortality (HR = 1.219, 95% CI 1.095-1.357; P < 0.001) and 360-day mortality (HR = 1.263, 95% CI 1.159-1.376; P < 0.001) in the high BAR group compared to the low BAR group. For the 30-day outcome, the area under the curve (AUC) was 0.661 for BAR and 0.668 for 360-day BAR. In the subgroup analysis, BAR remained an isolated risk factor for patient death. As a clinically inexpensive and readily available parameter, BAR can be a valuable forecaster of prognosis in patients with sepsis in the intensive care unit.

Association between red blood cell distribution width to albumin ratio and prognosis of patients with sepsis: A retrospective cohort study

Background

Red blood cell distribution width (RDW) to albumin ratio (RAR) is associated with poor prognosis in diabetic comorbidities and cancer. However, the association between RAR and prognosis in patients with sepsis remains unclear, which was investigated in this study.

Methods

We conducted a retrospective cohort study based on the Medical Information Mart for Intensive Care (MIMIC) IV version 2.0 database. The primary outcome of this study was 28-day mortality. Secondary outcomes included 90-day mortality, in-hospital mortality, length of hospital stay, and length of intensive care unit (ICU) stay. Multivariate regression analysis and subgroup analysis were performed to investigate the association between RAR and prognosis in patients with sepsis.

Results

A total of 14,639 participants were included in this study. The mean age of the participants was 65.2 ± 16.3 years and the mean RAR was 5.5 ± 1.9 % /g/dl. For 28-day mortality, after adjusting for covariates, HRs [95% confidence intervals (CIs)] for tertiles 2 (4.4–5.8) and 3 (RAR > 5.8) were 1.33 (1.20, 1.46) and 1.98 (1.79, 2.19), respectively. Similar results were observed for 90-day mortality and in-hospital mortality. According to Kaplan-Meier curve analysis, the higher RAR group had higher 28-day mortality and 90-day mortality.

Conclusion

Our study shows that RAR is significantly associated with poor clinical prognosis in sepsis. The higher the RAR, the higher the 28-day, 90-day, and in-hospital mortality.

New Perspectives on the Importance of Cell-Free DNA Biology

Body fluids are constantly replenished with a population of genetically diverse cell-free DNA (cfDNA) fragments, representing a vast reservoir of information reflecting real-time changes in the host and metagenome. As many body fluids can be collected non-invasively in a one-off and serial fashion, this reservoir can be tapped to develop assays for the diagnosis, prognosis, and monitoring of wide-ranging pathologies, such as solid tumors, fetal genetic abnormalities, rejected organ transplants, infections, and potentially many others. The translation of cfDNA research into useful clinical tests is gaining momentum, with recent progress being driven by rapidly evolving preanalytical and analytical procedures, integrated bioinformatics, and machine learning algorithms. Yet, despite these spectacular advances, cfDNA remains a very challenging analyte due to its immense heterogeneity and fluctuation in vivo. It is increasingly recognized that high-fidelity reconstruction of the information stored in cfDNA, and in turn the development of tests that are fit for clinical roll-out, requires a much deeper understanding of both the physico-chemical features of cfDNA and the biological, physiological, lifestyle, and environmental factors that modulate it. This is a daunting task, but with significant upsides. In this review we showed how expanded knowledge on cfDNA biology and faithful reverse-engineering of cfDNA samples promises to (i) augment the sensitivity and specificity of existing cfDNA assays; (ii) expand the repertoire of disease-specific cfDNA markers, thereby leading to the development of increasingly powerful assays; (iii) reshape personal molecular medicine; and (iv) have an unprecedented impact on genetics research.

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

Background

Cell free DNA, in the form of nucleosomes, is released into circulation during apoptosis and necrosis in a variety of diseases. They are small fragments of chromosomes that are composed of DNA wrapped around a histone core made of four duplicate histone proteins forming an octamer. The nucleosome compartment is a relatively uninvestigated area of circulating tumor biomarkers in dogs. The objectives of this study were to quantify and better characterize nucleosome concentrations in 528 dogs with various common malignancies and compare them to 134 healthy dogs.

Results

The sensitivity of increased circulating nucleosome concentrations for the detection of cancer in all dogs was 49.8% with a specificity of 97% with an area under the curve of 68.74%. The top 4 malignancies detected by the test included lymphoma, hemangiosarcoma, histiocytic sarcoma and malignant melanoma. The malignancies least likely to be detected were soft tissue sarcomas, osteosarcoma and mast cell tumors.

Conclusions

A variety of tumor types may cause increased nucleosome concentrations in dogs. Tumors of hematopoietic origin are most likely to cause elevations and local tumors such as soft tissue sarcomas are least likely to cause elevations in plasma nucleosome concentrations.

Investigation of plasma cell-free DNA as a potential biomarker in horses

Plasma cell-free DNA (cfDNA) is a biomarker of ischemia, systemic inflammation, and mortality in humans with gastrointestinal disease. Cell-free DNA has not been investigated as a biomarker for equine colic, to our knowledge. We hypothesized that cfDNA could be measured accurately in neat equine plasma using a benchtop fluorometer and that plasma cfDNA would be elevated in emergency patients compared to healthy horses. Plasma was obtained from blood collected in Roche DNA stabilizing tubes. We used the Qubit 4 fluorometer and 1× dsDNA HS assay kit to measure cfDNA concentration in neat patient plasma and following DNA extraction of plasma with a commercial kit. Assay precision and linearity of dilution were satisfactory for neat plasma cfDNA, but DNA spike and recovery results were variable. Further, cfDNA concentrations in paired neat plasma and extracted-plasma samples (n = 66) were not correlated. Median extracted-plasma cfDNA was higher in emergency patients (n = 50) and a subgroup of colic patients (n = 36), compared to healthy horses (n = 19). Our results with extracted-plasma samples provide proof of concept for further investigation of plasma cfDNA as a biomarker in horses.

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

BACKGROUND

Prolonged antimicrobial drug (AMD) treatment is associated with antimicrobial resistance development. Biomarker measurement may aid treatment decision-making.

OBJECTIVES

Investigate temporal changes in blood biomarker concentrations in dogs undergoing treatment for pulmonary and intra-abdominal infections; compare time to biomarker concentration normalization with duration of clinician-directed AMD treatment.

ANIMALS

Forty-two client-owned dogs with pneumonia (n = 22), septic peritonitis (n = 10), or pyometra (n = 10).

METHODS

Plasma concentrations of C-reactive protein (CRP), serum amyloid A (SAA), haptoglobin, procalcitonin, nucleosomes, cell-free DNA (cfDNA), high-mobility group box-1 (HMGB1), CC-motif chemokine ligand-2 (CCL2), CXC-motif chemokine ligand-8 (CXCL8), and keratinocyte chemoattractant-like (KC-Like) were quantitated in samples collected on days 1, 3, 7, 14, 28, and 60. Treatment was directed by clinicians blinded to biomarker concentrations.

RESULTS

Concentrations of CCL2, CRP, and KC-Like were maximal on D1, concentrations of SAA, cfDNA, HMGB1, and nucleosomes were maximal on D3 and haptoglobin concentrations were maximal on D7. These maximal concentrations were significantly different from those on D60. Concentrations of CRP and SAA decreased by 80% from peak and into respective reference intervals before AMDs were discontinued. For CRP, the median (interquartile range [IQR]) times to 20% peak and normal were 7 (6-9) and 7 (6-12) days, respectively, and for SAA they were 4 (4, 5) and 6 (5-8) days, respectively, compared to a median (IQR) duration of AMD prescribing of 16 (12-23) days (all P < .0001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Biomarker concentrations normalized within 7 to 14 days. Serial measurements of CRP and SAA might aid identification of disease resolution and could help guide AMD prescription decision-making.

A feasibility study investigating the utility of a point-of-care rapid immunoassay for detecting septic peritoneal effusion in dogs

OBJECTIVE

To determine the sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy of a point-of-care urine bacterial rapid immunoassay (RIA) for a diagnosis of septic peritonitis, compared to more traditional diagnostic tools, such as cytology and bacterial culture.

DESIGN

Prospective, cross-sectional feasibility study conducted from October 2016 to June 2017.

SETTING

Four locations within a private practice referral hospital.

ANIMALS

Sixty-four dogs with peritoneal effusion of any etiology were enrolled. Four dogs were excluded due to absent RIA or bacterial culture results. Two additional dogs were excluded because of an inability to definitively classify them as having septic peritonitis.

INTERVENTIONS

Abdominocentesis was performed to obtain peritoneal effusion samples for aerobic and anaerobic bacterial culture, cytology, and RIA. Cytological slides were evaluated by a clinical pathologist following enrollment.

MEASUREMENTS AND MAIN RESULTS

Fifty-eight dogs were included in the study, 8 of which were classified as having septic peritonitis. Compared to final diagnosis of septic peritonitis, RIA had a low PPV (36.8%) but good NPV (97.4%) and was 77.5% accurate. SN of RIA (87.5%) to diagnose septic peritonitis was similar to cytology (85.7%) and bacterial culture (87.5%); however, SP was lower (76%, 100%, and 98%, respectively). Cytology had the best overall predictive values and accuracy for diagnosing septic peritonitis (PPV 100%, NPV 97.9%, and accuracy 98%) compared to RIA and bacterial culture.

CONCLUSIONS

RIA testing was similarly sensitive in identifying septic peritonitis compared to cytology and bacterial culture but was not very specific or accurate. As a stand-alone test, RIA commonly had false-positive test results, making it unreliable in identifying septic peritonitis. Cytology was the most accurate diagnostic test and had no false-positive results. Further investigation with a larger sample size and prevalence of septic peritonitis may prove beneficial.

Characterizing circulating nucleosomes in the plasma of dogs with lymphoma

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.

Characterizing circulating nucleosomes in the plasma of dogs with hemangiosarcoma

Background

Nucleosomes consist of DNA wrapped around a histone octamer core like thread on a spool to condense DNA as chromatin into chromosomes. Diseases such as cancer or inflammation lead to cell death, chromatin fragmentation and release of nucleosomes into the blood. The Nu.Q™ platform measures circulating nucleosomes in the blood of humans that result from disease and has been used to detect and identify cancer even at early stages. The objectives of this study are to quantify and better characterize nucleosomes in dogs with various stages of hemangiosarcoma (HSA) using this ELISA-based assay.

Samples from 77 dogs with a confirmed diagnosis of hemangiosarcoma and 134 healthy controls were utilized for this study. The HSA samples were recruited from the Texas A&M University Small Animal Clinic (TAMU-SAC) or purchased from biobanks. All control samples were recruited from the TAMU-SAC.

Results

Dogs with hemangiosarcoma had a 6.6-fold increase in their median plasma nucleosome concentrations compared to controls (AUC 92.9 %). Elevated nucleosome concentrations were seen at all stages of disease and nucleosome concentrations increased with the stage of the disease.

Conclusions

Plasma nucleosome concentrations are a reliable way to differentiate dogs with hemangiosarcoma from healthy dogs. Further testing is underway to better characterize cancer associated HSA circulating nucleosomes and optimize future diagnostics for canine HSA detection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02934-6.

Utility of cell-free DNA concentrations and illness severity scores to predict survival in critically ill neonatal foals

Plasma cell-free DNA (cfDNA) levels have been associated with disease and survival status in septic humans and dogs. To date, studies investigating cfDNA levels in association with critical illness in foals are lacking. We hypothesized that cfDNA would be detectable in the plasma of foals, that septic and sick-nonseptic foals would have significantly higher cfDNA levels compared to healthy foals, and that increased cfDNA levels would be associated with non-survival. Animals used include 80 foals of 10 days of age or less admitted to a tertiary referral center between January and July, 2020 were stratified into three categories: healthy (n = 34), sick non-septic (n = 11) and septic (n = 35) based on specific criteria. This was a prospective clinical study. Blood was collected from critically ill foals at admission or born in hospital for cfDNA quantification and blood culture. Previously published sepsis score (SS) and neonatal SIRS score (NSIRS) were also calculated. SS, NSIRS, blood culture status and cfDNA concentrations were evaluated to predict survival. Continuous variables between groups were compared using Kruskal-Wallis ANOVA with Dunn’s post hoc test. Comparisons between two groups were assessed using the Mann-Whitney U-test or Spearman rank for correlations. The performance of cfDNA, sepsis score and NSIRS score to predict survival was assessed by receiver operator characteristic (ROC) curve analysis including area under the curve, sensitivity and specificity using cutoffs. Plasma cfDNA was detectable in all foals. No significant differences in cfDNA concentration were detected between healthy foals and septic foals (P = 0.65) or healthy foals and sick non-septic foals (P = 0.88). There was no significant association between cfDNA and culture status, SS, NSIRS or foal survival. SS (AUC 0.85) and NSIRS (AUC 0.83) were superior to cfDNA (AUC 0.64) in predicting survival. Although cfDNA was detectable in foal plasma, it offers negligible utility to diagnose sepsis or predict survival in critical illness in neonates.

Horizons in Veterinary Precision Oncology: Fundamentals of Cancer Genomics and Applications of Liquid Biopsy for the Detection, Characterization, and Management of Cancer in Dogs

Cancer is the leading cause of death in dogs, in part because many cases are identified at an advanced stage when clinical signs have developed, and prognosis is poor. Increased understanding of cancer as a disease of the genome has led to the introduction of liquid biopsy testing, allowing for detection of genomic alterations in cell-free DNA fragments in blood to facilitate earlier detection, characterization, and management of cancer through non-invasive means. Recent discoveries in the areas of genomics and oncology have provided a deeper understanding of the molecular origins and evolution of cancer, and of the "one health" similarities between humans and dogs that underlie the field of comparative oncology. These discoveries, combined with technological advances in DNA profiling, are shifting the paradigm for cancer diagnosis toward earlier detection with the goal of improving outcomes. Liquid biopsy testing has already revolutionized the way cancer is managed in human medicine - and it is poised to make a similar impact in veterinary medicine. Multiple clinical use cases for liquid biopsy are emerging, including screening, aid in diagnosis, targeted treatment selection, treatment response monitoring, minimal residual disease detection, and recurrence monitoring. This review article highlights key scientific advances in genomics and their relevance for veterinary oncology, with the goal of providing a foundational introduction to this important topic for veterinarians. As these technologies migrate from human medicine into veterinary medicine, improved awareness and understanding will facilitate their rapid adoption, for the benefit of veterinary patients.

Hypophosphatemia in Dogs With Presumptive Sepsis: A Retrospective Study (2008-2018)

Background: In humans with sepsis, hypophosphatemia is a marker of illness severity and a negative prognostic indicator. Hypophosphatemia has not been previously investigated in dogs with sepsis, however. This study aimed to estimate the prevalence of hypophosphatemia in dogs, the prevalence of presumptive sepsis in dogs with hypophosphatemia, the prevalence of hypophosphatemia in dogs with presumptive sepsis and the association between outcome and hypophosphatemia in dogs with presumptive sepsis. Methods: Electronic medical records of the Cornell University Hospital for Animals from 2008-2018 were queried to identify all dogs with hypophosphatemia and all dogs with presumptive sepsis. Hypophosphatemia was defined as a serum phosphate concentration <2.7 mg/dL. Sepsis was presumed where ≥2 of 4 systemic inflammatory response syndrome (SIRS) criteria were satisfied associated with a documented or highly suspected infection. Variables were assessed for normality using the D'Agostino-Pearson test. Continuous variables were compared between groups using the Mann-Whitney U test. Differences in frequency between categorical variables were analyzed using contingency tables, calculation of Fisher's exact test or Chi² and estimation of odds ratios. Results: In the study period, 47,992 phosphate concentration measurements from 23,752 unique dogs were identified. After eliminating repeat analyses, the period prevalence of hypophosphatemia on a per dog basis over the 11-year study period was 10.6% (2,515/23,752). The prevalence of presumptive sepsis within dogs with hypophosphatemia was 10.7% (268/2,515). During the 11-year study period, 4,406 dogs with an infection were identified, of which 1,233 were diagnosed with presumptive sepsis and had a contemporaneous phosphate concentration. Hypophosphatemia was more prevalent in dogs with presumptive sepsis than in dogs without 21.7 vs. 10.2%; OR 2.44 [95% CI 2.12-2.81]; P < 0.0001. The mortality rate was greater in dogs with hypophosphatemia and presumptive sepsis than in dogs with hypophosphatemia without presumptive sepsis (15.3 vs. 3.1%; OR 5.70 [95% CI 3.76-8.52]; P < 0.0001), however hypophosphatemia was not associated with outcome in dogs with presumptive sepsis OR 0.87 [95% CI 0.60-1.26]; P = 0.518. Conclusions: In dogs with hypophosphatemia, a presumed diagnosis of sepsis was associated with increased mortality compared to other associated disease processes. In dogs with presumptive sepsis, hypophosphatemia was not associated with outcome.

Troxerutin attenuates inflammatory response in lipopolysaccharide-induced sepsis in mice

Troxerutin (Tx), known as vitamin P₄ is a derivative of natural bioflavonoid rutin. Tx possesses different biological activities such as antioxidant, anticancer, and anti-inflammatory. The current study was conducted to determine potential therapeutic effect of Tx in lipopolysaccharides (LPS)-induced sepsis in mice. In LPS-induced sepsis, the mice were treated intraperitoneally (ip) with Tx twice daily. Therapeutic effect was assessed by measuring serum level of cytokines, alanine aminotransferase (ALT) and lactate dehydrogenase (LDH). Level of nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT), Myeloperoxidase (MPO) and Malondialdehyde (MDA) was measured. Expression of CD40 receptor on leucocytes was measured using flowcytometry. Splenocyte proliferation was evaluated using MTT assay. The effect of Tx on survival rate during administration of lethal dose of LPS was investigated. The results showed that Tx inhibited LPS induced NO production. Inflammatory pathways were suppressed by reduction of inflammatory cytokines production. Further, elevated CD40 expression of leucocytes and proliferation of splenocytes markedly reduced in Tx treated group. Antioxidant defense system was enhanced by increased activity of SOD and CAT and decreased level of MDA. MPO, ALT and LDH activity. Additionally, treatment with Tx significantly increased the mean survival time of mice compared with the LPS treated group. Histologically, Tx treatment decreased inflammatory cells infiltration and histopathologicl changes in the liver. Our findings showed that reduced inflammatory parameters, improved antioxidant activity, reduced histological lesions and increased survival rate. These findings suggest that Tx is an effective anti-inflammatory agent for the treatment of LPS-induced sepsis.

Presence of nucleosomes in plasma and increased thrombin generation in dogs with acute and chronic gastroenteropathies

Neutrophil extracellular traps (NETs) which contain nucleosomes protect the host by eliminating extracellular pathogens. However, any inflammatory stimuli can activate NETs and eventually lead to an immune overreaction leading to autoimmune diseases and thrombosis. Acute/chronic gastroenteropathies(aGE/cGE) are prevalent in dogs, and are associated with a strong inflammatory component. The aim of this study was to investigate if dogs with aGE and cGE have increased concentrations of nucleosomes indicative of NETs formation, and whether increased concentrations of nucleosomes are associated with hypercoagulability determined by increased thrombin generation. Twenty-six dogs were enrolled. The dogs were healthy (n = 11), or presented with aGE(n = 7) or cGE(n = 8). Minimum database including CRP, APTT, PT and fibrinogen, was obtained from all dogs. Citrated plasma was batched and used for subsequent analyses. Nucleosome concentration was analysed using a Cell-Death Detection ELISA-kit and thrombin generation by a calibrated automated thrombogram assay. No statistical differences in nucleosome concentrations were present between the groups. Although a numerically increased concentration of nucleosomes where seen in dogs with aGE(median;range) (0.019 AU;0.003-0.088) and cGE(0.023 AU;0.011-0.256) compared to controls(0.007 AU;0.003-0.042). One dog with GI-lymphoma demonstrated a markedly increased concentration of nucleosomes (0.256 AU). Dogs with aGE showed increased thrombin generation by increased peak (p = 0.03) and endogenous thrombin potential (p = 0.03); and increased CRP (p = 0.001), fibrinogen (p = 0.0002) and prolonged APTT (p = 0.03) compared to controls. This proof of concept study demonstrates that dogs with aGE and cGE have presence of nucleosomes with marked increase in one dog with GI-lymphoma. Nucleosomes might be linked to haemostatic alterations in dogs with inflammatory and neoplastic diseases.

Evaluation of nucleosome concentrations in healthy dogs and dogs with cancer

INTRODUCTION

Nucleosomes consist of small fragments of DNA wrapped around a histone octamer core. Diseases such as cancer or inflammation lead to cell death, which causes fragmentation and release of nucleosomes into the blood. The Nu.Q™ technology measures circulating nucleosome levels and exploits the different compositions of cancer derived nucleosomes in blood to detect and identify cancer even at early stages. The objectives of this study are to identify the optimal sample type for the Nu.Q™ H3.1 assay and to determine if it can accurately detect nucleosomes in the blood of healthy canines as well as those with cancer.

MATERIALS AND METHODS

Blood samples from healthy canine volunteers as well as dogs newly diagnosed with lymphoma were used. The blood was processed at a variety of times under a variety of conditions to determine the most reliable sample type and conditions, and to develop an appropriate processing strategy to ensure reliably accurate results.

RESULTS

Nucleosomes could be detected using a variety of sample collection and processing protocols. Nucleosome signals were highest in EDTA plasma and serum samples and most consistent in plasma. Samples should be processed within an hour of collection. Experiments showed that samples were able to withstand several freeze thaw cycles. Processing time and tcollection tube type did affect nucleosome detection levels. Finally, significantly elevated concentrations of nucleosomes were seen in a small cohort of dogs that had been newly diagnosed with lymphoma.

CONCLUSIONS

When samples are collected and processed appropriately, the Nu.Q™ platform can reliably detect nucleosomes in the plasma of dogs. Further testing is underway to validate and optimize the Nu.Q™ platform for veterinary use.

Prognostic role of red blood cell distribution width in patients with sepsis: a systematic review and meta-analysis

Background

Outcome prediction for patients with sepsis may be conductive to early aggressive interventions. Numerous biomarkers and multiple scoring systems have been utilized in predicting outcomes, however, these tools were either expensive or inconvenient.

We performed a meta-analysis to evaluate the prognostic role of red blood cell distribution width (RDW) in patients with sepsis.

Methods

The online databases of Embase, Web of science, Pubmed, Corchrane library, Chinese Wanfang database, CNKI database were systematically searched from the inception dates to June, 24th, 2020, using the keywords red cell distribution width and sepsis. The odds ratio (OR) or Hazards ratio (HR) with corresponding 95% confidence intervals (95%CI) were pooled to evaluate the association between baseline RDW and sepsis. A random-effects model was used to pool the data, and statistical heterogeneity between studies was evaluated using the I² statistic. Sensitivity and subgroup analyses were performed to detect the publication bias and origin of heterogeneity.

Results

Eleven studies with 17,961 patients with sepsis were included in the meta-analysis. The pooled analyses indicated that increased baseline RDW was associated with mortality (HR = 1.14, 95%CI 1.09–1.20, Z = 5.78, P < 0.001) with significant heterogeneity (I² = 80%, P_{heterogeneity} < 0.001). Similar results were found in the subgroup analysis stratified by site of infection, comorbidity, Newcastle-Ottawa Scale (NOS) score, study design, patients’ country. The predefined subgroup analysis showed that NOS score may be the origin of heterogeneity.

Conclusions

For patients with sepsis, baseline RDW may be a useful predictor of mortality, patients with increased RDW are more likely to have higher mortality.

Evaluation of cell-free DNA as a diagnostic marker in cerebrospinal fluid of dogs

OBJECTIVE

To determine whether cell-free DNA (cfDNA) was detectable in CSF samples from dogs, whether CSF sample volume impacted CSF cfDNA concentration measurement, and whether CSF cfDNA concentration was associated with CNS disease category or CSF RBC count (RBCC), nucleated cell count (NCC), or protein concentration, which could aid in the diagnosis of neurologic diseases in dogs.

SAMPLE

80 CSF samples collected from dogs with (n = 60) and without (20) clinical neurologic disease between February 2017 and May 2018.

PROCEDURES

Results for CSF RBCC, NCC, protein concentration, and cfDNA concentration were compared across CSF groups established on the basis of whether they were obtained from dogs with (case groups) or without (control group) clinical signs of neurologic disease In addition, 5 paired CSF samples representing large (3.0-mL) and small (0.5-mL) volumes, were used to evaluate whether sample volume impacted measurement of CSF cfDNA concentration.

RESULTS

cfDNA was detected in 76 of the 80 (95%) CSF samples used to evaluate parameters across disease categories and in all 5 of the paired samples used to evaluate whether sample volume impacted cfDNA quantification. There were no substantial differences in cfDNA concentrations identified between groups (on the basis of disease category or sample volume), and the CSF cfDNA concentration did not meaningfully correlate with CSF RBCC, NCC, or protein concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Although results indicated that the CSF cfDNA concentration could not be used to differentiate between categories of neurologic disease in dogs of the the present study, further investigation is warranted regarding the use of CSF analysis, including sequencing specific cfDNA mutations, for diagnosing and monitoring neurologic disease in dogs.

Evaluation of the host cytokine response in dogs with sepsis and noninfectious systemic inflammatory response syndrome

OBJECTIVE

To quantify plasma cytokine concentrations in dogs with sepsis and noninfectious systemic inflammation and to evaluate the association between plasma cytokines and outcome in dogs with sepsis.

DESIGN

Prospective, observational cohort study.

SETTING

University teaching hospital.

ANIMALS

Forty-five dogs with sepsis, 10 dogs with noninfectious systemic inflammation (nSIRS), and 15 healthy controls were consecutively enrolled from June 2015 to February 2016 and followed to hospital discharge. Dogs with sepsis satisfied ≥2 SIRS criteria and had a documented or highly suspected bacterial infection. Dogs with nSIRS satisfied ≥2 SIRS criteria but had no evidence of infection. Dogs <3 kg and those with documented coagulopathy were excluded.

INTERVENTIONS

Measurement of inflammatory cytokines and high-mobility group box-1 (HMGB-1) was performed on each group.

MEASUREMENTS AND MAIN RESULTS

High-mobility group box-1 concentrations were analyzed by ELISA. Plasma concentrations of 13 cytokines were measured in singlet using multiplex magnetic bead assays. Kruskal-Wallis with Dunn's multiple comparison tests were used to compare biomarker concentrations between groups. Mann-Whitney U-tests were used to compare biomarker concentrations between survivors and nonsurvivors. Associations between biomarkers were evaluated using Spearman's correlation coefficients. Independent outcome predictors were identified using multivariable logistic regression. Alpha was set at 0.05. Concentrations of interleukin (IL)-6, C-X-C motif chemokine (CXCL)-8, keratinocyte-derived chemokine (KC)-like, C-C motif chemokine ligand 2 (CCL2), and HMGB-1 were significantly greater in dogs with sepsis versus healthy controls (all P ≤ 0.034). In dogs with sepsis, only CCL2 was independently associated with survival (odds ratio [OR] 0.996, 95% CI 0.993-0.999, P = 0.004). A cut-off of 385 pg/mL for CCL2 was 80% sensitive and 91.4% specific for nonsurvival (area under the ROC curve [AUROC] 0.866).

CONCLUSIONS

Dogs with sepsis have significantly increased concentrations of HMGB-1 and inflammatory cytokines, including IL-6, CXCL8, and KC-like. Increased CCL2 concentration is a negative prognostic indicator in dogs with sepsis. These findings should be confirmed using duplicate analyses in larger, distinct populations of dogs with sepsis before applying them to clinical patients.

Effect of sample type on plasma concentrations of cell-free DNA and nucleosomes in dogs

Cell-free DNA (cfDNA) and nucleosomes are two biomarkers of cell death and neutrophil extracellular trap formation that are increased in dogs with sepsis, immune-mediated haemolytic anaemia, cancer and following trauma and have diagnostic and prognostic values. cfDNA and nucleosomes are typically measured in plasma samples using DNA-specific fluorophores and ELISA assays, respectively, but their concentrations may be affected by pre-analytical variables such as sample type. The present study aimed to investigate the influence of sample type on the plasma cfDNA and nucleosome concentrations of a heterogeneous group of dogs presenting to an emergency room. Triplicate samples were collected into K₂-ethylenediamine tetraacetic acid, 3.2% citrate and a specialised DNA stabilisation tube (Streck BCT), processed rapidly and frozen for batch analysis. Biomarker concentrations were compared between sample types by calculation of Spearman’s correlation coefficients, and with Deming regression, Bland-Altman plots and the Friedman test. Overall, biomarker concentrations were highly correlated between the three sample types. The most concordant results were obtained using citrate samples and the DNA stabilisation tube. Matched cfDNA concentrations between the different sample types were significantly different but there was no significant difference between the nucleosome concentrations in any of the sample types. The present study suggests that cfDNA and nucleosomes can be successfully measured in various sample types, but distinct sample types do not produce interchangeable results. This argues for use of a consistent sample type within studies and suggests standardisation may be useful for the field.

Neutrophil-Extracellular Traps, Cell-Free DNA, and Immunothrombosis in Companion Animals: A Review

Immunothrombosis is a potentially beneficial physiological process that aids innate immunity and host defense against pathogen invasion. However, this process can also be damaging when it occurs to excess or in critical blood vessels. Formation of extracellular traps by leukocytes, particularly neutrophils, is central to our understanding of immunothrombosis. In addition to degranulation and phagocytosis, extracellular traps are the third mechanism by which neutrophils combat potential pathogens. These traps consist of extracellular DNA decorated with bactericidal cellular proteins, including elastase, myeloperoxidase, and cathepsins. Neutrophils can release these structures as part of a controlled cell-death process or via a process termed vital NETosis that enables the cells to extrude DNA but remain viable. There is accumulating evidence that NETosis occurs in companion animals, including dogs, horses, and cats, and that it actively contributes to pathogenesis. Numerous studies have been published detailing various methods for identification and quantification of extracellular trap formation, including cell-free DNA, measurements of histones and proteins such as high-mobility group box-1, and techniques involving microscopy and flow cytometry. Here, we outline the present understanding of these phenomena and the mechanisms of extracellular trap formation. We critically review the data regarding measurement of NETosis in companion animals, summarize the existing literature on NETosis in veterinary species, and speculate on what therapeutic options these insights might present to clinicians in the future.

Biomarker Guided Diagnosis of Septic Peritonitis in Dogs

Septic peritonitis (SP) is common in dogs and is associated with high mortality. Early recognition is essential to maximizing survival and may be aided by biomarker measurement. The present study aimed to evaluate the ability of biomarkers to discriminate septic peritonitis from non-septic ascites (NSA). Eighteen dogs with SP and 19 age-matched controls with NSA were enrolled. Contemporaneous blood and peritoneal effusion samples were obtained. Concentrations of cell-free DNA (cfDNA), cytokines, glucose, lactate, N-terminal pro-C-type natriuretic peptide (NT-proCNP), nucleosomes, and procalcitonin (PCT) were measured using commercial reagents and assays. Paired biomarker concentrations were compared with the Wilcoxon matched-pairs signed rank test, and biomarker concentrations between groups were compared with the Mann-Whitney U-test. P-values were adjusted for multiple comparisons using the Bonferroni correction. Receiver operating characteristic curves were generated to assess the ability of the above biomarkers to discriminate SP from NSA. Dogs with SP had significantly greater blood CCL2 concentrations than dogs with NSA (P = 0.032). Dogs with SP had significantly greater effusion CCL2, IL-6, IL-10, and lactate concentrations than dogs with NSA (P ≤ 0.0121). Blood-effusion concentration gradients of CCL2, glucose, IL-6, IL-10, and lactate were significantly different in dogs with SP compared to dogs with NSA (P ≤ 0.0165). Effusion lactate concentration had the highest AUROC value (0.866, 95% CI 0.751–0.980, P = 0.0001), although other biomarkers performed similarly. An effusion lactate concentration of 4.2 mmol/L was 72.2% (95% CI 46.5–90.3%) sensitive and 84.2% (95% CI 60.4–96.6%) specific for the diagnosis of SP.

A Comparative Review of Equine SIRS, Sepsis, and Neutrophils

The most recent definition of sepsis in human medicine can be summarized as organ dysfunction caused by a dysregulated host response to infection. In equine medicine, although no consensus definition is available, sepsis is commonly described as a dysregulated host systemic inflammatory response to infection. Defense against host infection is the primary role of innate immune cells known as neutrophils. Neutrophils also contribute to host injury during sepsis, making them important potential targets for sepsis prevention, diagnosis, and treatment. This review will present both historical and updated perspectives on the systemic inflammatory response (SIRS) and sepsis; it will also discuss the impact of sepsis on neutrophils, and the impact of neutrophils during sepsis. Future identification of clinically relevant sepsis diagnosis and therapy depends on a more thorough understanding of disease pathogenesis across species. To gain this understanding, there is a critical need for research that utilizes a clearly defined, and consistently applied, classification system for patients diagnosed with, and at risk of developing, sepsis.