Association of acute Babesia canis infection and serum lipid, lipoprotein, and apoprotein concentrations in dogs

Serum proteome profiling of naturally acquired Babesia rossi infection in dogs

Babesiosis is a disease of significant medically and veterinary importance with worldwide distribution. It is caused by intra-erythrocyte protozoal parasites, with Babesia rossi causing the most severe clinical signs of all the large Babesia parasites infecting dogs. The disease can be clinically classified into uncomplicated and complicated forms with a wide range of clinical presentations from a mild, subclinical illness to complicated forms and death. The aim of this study was to assess serum proteomic profiles from dogs with babesiosis and healthy dogs using a label-based proteomics approach. Altogether 32 dogs naturally infected with B. rossi (subdivided into 18 uncomplicated cases and 14 complicated cases of babesiosis) and 20 healthy dogs were included. There were 78 proteins with significantly different abundances between the three groups of dogs. Elucidation of proteins and pathways involved in canine babesiosis caused by B. rossi have revealed key differences associated with haemostasis, innate immune system, lipid metabolism and inflammation. Shotgun proteomic profiling allowed identification of potential serum biomarkers for differentiation of disease severity in canine babesiosis caused by B. rossi. These findings may be applicable to the study of host-parasite interactions and the development of novel therapeutic targets.

Reduced Cholesterol Levels during Acute Human Babesiosis

BACKGROUND

Babesiosis, an intra-erythrocytic protozoan disease, is an emerging zoonotic parasitic disease worldwide. Cholesterol levels are correlated with severe infections, such as sepsis and COVID-19, and anecdotal reports suggest that high-density lipoprotein (HDL) cholesterol declines during acute babesiosis. Our aim was to describe the cholesterol levels in patients with acute babesiosis diagnosed in an endemic area in New York, hypothesizing that HDL levels correlate with the severity of infection.

METHODS

We reviewed the medical records of adult patients with babesiosis diagnosed by identification of Babesia parasites on a thin blood smear and confirmed by polymerase chain reaction from 2013 to 2018, who also had available a lipid profile drawn at the time of clinical presentation. Additional lipid profile levels were considered as "baseline" if they were drawn within 2 months before or after the infection as part of routine care.

RESULTS

A total of 39 patients with babesiosis had a lipid profile drawn on presentation. The patients were divided into two groups for comparison based on the treating physician's clinical decision: 33 patients who were admitted to the hospital and 8 patients who were evaluated as outpatients. A history of hypertension was more common in admitted patients (37% vs. 17%, p = 0.02). The median levels of low-density lipoprotein (LDL) and HDL were significantly reduced in admitted patients compared to non-admitted patients (46 vs. 76 mg/dL, p = 0.04; and 9 vs. 28.5 mg/dL, p = 0.03, respectively). In addition, LDL and HDL levels returned to baseline values following resolution of acute babesiosis.

CONCLUSION

LDL and HDL levels are significantly reduced during acute babesiosis, suggesting that cholesterol depletion may predict disease severity. Pathogen and host factors may contribute to a reduction in serum cholesterol levels during acute babesiosis.

Spurious capillary zone electrophoresis pattern in hypercholesterolemic dogs

Capillary zone electrophoresis (CZE) is a relatively new serum protein electrophoresis method with higher resolution than other electrophoretic techniques. Hypercholesterolemic dogs exhibit a peculiar CZE pattern. Specifically, they have a shoulder or peak immediately next to the albumin peak. We investigated the prevalence of this spurious peak in hypercholesterolemic dogs and its correlation with the serum cholesterol concentration. Moreover, possible discrepancies between the CZE and spectrophotometric (bromocresol green [BCG] method) albumin concentrations in those animals were evaluated, as well as the accuracy in measuring albumin by a different CZE fractionation system. We retrospectively enrolled 500 hypercholesterolemic and normotriglyceridemic dogs. Each electrophoretic curve was inspected visually to identify a spurious peak (prevalence of 68.8%). We chose 120 dogs to further investigate the albumin concentration; CZE albumin was significantly higher than measured using the BCG method. A weak but significant correlation (r = 0.412; p <0.0001) was observed between the magnitude of the spurious peak and the serum cholesterol concentration. Finally, the significant difference between CZE and BCG albumin measurement disappeared (p = 0.92) when the spurious peak was considered as α1-globulins instead of albumin.

Apolipoprotein A1 and serum amyloid A in dogs with sepsis and septic shock

Introduction

Apolipoprotein-A1 (Apo-A1) acts as a negative acute phase protein (APP) during inflammatory states, and has a potential prognostic value in people and dogs with sepsis. The aim of this retrospective study was to investigate the association of serum Apo-A1 concentration with disease severity, multiorgan dysfunction syndrome (MODS) and outcome in a population of dogs with sepsis, and to assess its correlation with major canine APPs.

Methods

Ninety-nine dogs with uncomplicated sepsis (n = 78) or septic shock (n = 21) were included. The serum concentration of Apo-A1, C-reactive protein (CRP) and serum amyloid A (SAA) were recorded, alongside the canine acute patient physiologic and laboratory evaluation fast (APPLE_fast) score and the presence of MODS.

Results

Dogs with septic shock had significantly lower serum Apo-A1 concentrations (106.3 ± 22.7 mg/dl; reference interval: 123.0-142.3 mg/dl), higher APPLE_fast score (30, 13-38) and greater frequency of MODS (67%) compared to those with uncomplicated sepsis (117.9 ± 19.3 mg/dl; 25, 6-33 and 8%, respectively) (P = 0.0201; P = 0.0005; P < 0.0001, respectively). Similarly, dogs with MODS had significantly lower serum Apo-A1 concentrations (104.1 ± 4.6 mg/dl) and higher APPLE_fast score values (31, 13-38) compared to those without MODS (118.32 ± 2.1 mg/dl and 26, 6-33, respectively) (P = 0.0050 and P = 0.0038, respectively). Conversely, neither CRP nor SAA were different between these groups. No difference in serum APPs concentrations was detected between survivors and non-survivors. Significant negative correlations were detected between serum Apo-A1 and SAA (P = 0.0056, r = -0.277), and between serum Apo-A1 and the APPLE_fast score (P = 0.0027, r = -0.3). In this population, higher values of the APPLE_fast score and the presence of MODS were independently associated with a higher risk of death.

Discussion

Our study shows that Apo-A1 is a useful biomarker of sepsis severity in dogs, since it is decreased in those with septic shock and MODS. Further prospective investigations are deemed to evaluate the applicability of Apo-A1 to predict sepsis course and response to treatment in septic dogs.

Acute phase protein response and changes in lipoprotein particle size in dogs with systemic inflammatory response syndrome

Background

Improved methodology to measure acute phase proteins and determination of lipoprotein particle‐size distribution (PSD) could be clinically useful in dogs with systemic inflammatory processes.

Objectives

Evaluate an immunoturbidometric assay for serum amyloid A (SAA) and lipoprotein PSD in dogs with sepsis, nonseptic systemic inflammation, and in healthy controls. Correlate dyslipidemic changes with SAA and C‐reactive protein (CRP) concentrations.

Animals

Twenty‐five dogs with sepsis, 15 dogs with nonseptic systemic inflammation, and 22 healthy controls.

Methods

Prospective, case‐control study. Variables included SAA, CRP, and electrophoretic subfractionation of high‐ and low‐density lipoproteins (HDL, LDL). Continuous variables were compared using ANOVA or Kruskal‐Wallis tests with linear regression or Spearman's rank correlation used to assess relationships between variables.

Results

Median SAA and CRP concentrations were greater in dogs with sepsis (SAA 460 mg/L, interquartile range [IQR] 886 mg/L; CRP 133.2 mg/L, IQR 91.6 mg/L) and nonseptic inflammation (SAA 201 mg/L, IQR 436 mg/L; CRP 91.1 mg/L, IQR 88.6 mg/L) compared to healthy dogs (SAA 0.0 mg/L, IQR 0.0 mg/L; CRP 4.9 mg/L, IQR 0.0 mg/L) P < .0001. A cutoff of >677.5 mg/L SAA was 43.2% sensitive and 92.3% specific for sepsis. Low‐density lipoprotein was higher in dogs with sepsis 29.6%, (mean, SD 14.6) compared to 14.4% (mean, SD 5.6) of all lipoproteins in healthy controls (P = .005). High‐density lipoprotein was not associated with CRP but was negatively correlated with SAA (r_s −0.47, P < .0001). Subfractions of LDL and HDL differed between groups (all P < .05).

Conclusions and Clinical Importance

Measurement of SAA using the immunoturbidometric assay evaluated in this study and lipoprotein PSD in dogs with inflammation might help distinguish septic from nonseptic causes of inflammation.

Seasonal differences in the intensity of acute phase response in dogs infected with Babesia canis

The highest number of acute Babesia canis cases in dogs is recorded over the February-May (Feb-May) period, which also represents the optimal climate conditions for tick activity in Belgrade, Serbia. A possibility that the acute phase response is more intense in dogs developing the disease in the Feb-May period compared with the response in other time periods of the year was tested. A total of 63 client-owned dogs with acute B. canis infection were enrolled and the routine hematology and biochemistry parameters-serum amyloid A (SAA), IgG against B. canis, level of parasitemia, ceruloplasmin (CER), paraoxonase-1 (PON-1), and fibrinogen-were measured. Acute phase indexes (API) were calculated as (SAA×CER)/(Iron×PON-1) and (SAA×CER)/(Albumin×Iron). Statistics included Kruskal-Wallis test and logistic regression analysis. The results showed that in the Feb-May period, the following parameters were lower: creatinine, albumin, iron, and level of parasitemia. Furthermore, increased API values were more probable in the Feb-May than in the other periods. Together, higher acute phase response intensity and presumptive hemodilution in the Feb-May period indicate a more acute course of B. canis infection than in other time periods of the year.

Proteomics in dogs: a systematic review

Proteomic analysis is having a rapid development as a method for the detection of biomarkers of diseases in dogs. Dogs in addition to their importance as companion animals, serve as important animal models for research. This study aims to systematically review evidence regarding the studies performed in proteomics in dogs, and specifically those made in serum, saliva, urine and/or plasma. Information searched in October 2020, January 2021 and August 2021, for English language publications of the last decade (2010-2020) were obtained from electronic databases. Screening, data extraction and risk of bias assessment were undertaken by two investigators. The risk of bias was evaluated using the Review Manager (RevMan 5) tool. Meta-analysis and case report studies were not included in this review. Through the screening process a total of 557 publications were identified after the removal of duplicates. Out of these, 65 were fully evaluated and 44 of these were included in the review. Most studies evaluated the proteome of disease and compared it with a healthy population, and most of the articles included were made on serum, followed by saliva. The overall risk of bias for all studies was high, due to an absence in the generation of random sequence. Overall proteomic analysis has allowed the discovery of new physiopathological pathways of diseases and potential biomarkers in the dog, which are addressed in this review.

Low serum levels of promatrix metalloproteinase-2 and -9 occur during acute Babesia canis infection in dogs

Inflammation is a hallmark of the acute Babesia canis infection. Promatrix metalloproteinase (proMMP)-2 and -9 are involved in inflammation, but their levels have not been analyzed in canine babesiosis. We hypothesized that in dogs infected with B. canis, serum proMMP-2 and -9 levels change between presentation and recovery. Degree of the change differs if dogs develop systemic inflammatory response syndrome (SIRS). This study included 24 dogs with an acute B. canis infection, at presentation and after two weeks. We used routine hematology and biochemistry methods, spectrophotometry for the acute-phase proteins, microscopy for parasitemia and zymography for (pro)MMPs. In vitro endothelial cells and leukocyte short-term cultures, and platelet lysates were used to detect specific MMP activity. Statistical analyses included Wilcoxon test for paired samples, Mann-Whitney U test and Spearman's rank correlation. Our results showed that endothelial cells, leukocytes and platelets are the source of proMMP-2 and proMMP-9. Furthermore, both proMMPs were lower at presentation than after recovery (p < 0.001). At presentation, proMMP-9 levels correlated with parasitemia (rho = -0.616, p = 0.009), total leukocyte (rho = 0.704, p < 0.001) and neutrophil counts (rho = 0.741, p < 0.001). Extent of alterations in proMMP-2 levels between presentation and recovery was lower (p = 0.038) in dogs with SIRS than in non-SIRS dogs, while levels of proMMP-9 were comparable between these groups. Our conclusion is that during the acute B. canis infection, low serum levels of proMMP-2 and proMMP-9 at presentation reflect thrombocytopenia and leukopenia. Decreased proMMP-2 level could be associated with SIRS.

Relationship between Changes in Hematological Parameters, Levels of Acute Phase Proteins and Redox Homeostasis during Acute Babesia canis Infection in Dogs

Hemolysis and systemic acute inflammation characterize canine babesiosis caused by the intraerythrocytic protozoan parasite Babesia canis. Our hypothesis was that blood redox homeostasis of patients that suffered acute B. canis infection might be disturbed even after treatment with imidocarb-dipropionate and successful clinical recovery. Eight owner dogs with acute B. canis infection were used for this study. We analyzed the complete blood count, acute phase proteins (ceruloplasmin, haptoglobin, paraoxonase-1) in the serum, antioxidant enzymes (catalase and glutathione peroxidase) in the erythrocytes, and oxidative stress markers (malondialdehyde in erythrocytes and thiol groups in serum) at presentation and 15 days after treatment. Results were evaluated by corresponding statistical tests. At presentation, anemia, low/normal leukocyte count and severe thrombocytopenia occurred together with increased ceruloplasmin, haptoglobin levels within the reference interval, decreased paraoxonase-1 and compromised antioxidant defense in the red blood cells. After treatment and successful clinical recovery, hematological values generally fitted within the reference intervals, acute phase proteins were within the physiological levels in the majority of cases and the activities of the antioxidant enzymes were increased. However, elevated malondialdehyde levels indicated increased oxidative damage of erythrocytes that remained as a deleterious sequel despite a successful clinical recovery of the dogs.

Molecular Identification and Genotyping of Babesia canis in Dogs from Meshkin Shahr County, Northwestern Iran

Background

Canine babesiosis is one of the mainly worldwide-distributed tick-borne haemoprotozoan parasitic diseases in dogs.

Methods

A total of 43 blood samples were randomly collected from naturally infected dogs in seven villages from different geographical areas of Meshkin Shahr, Ardabil Province, Iran. The presence of Babesia species detected with standard methods including parasitological and gene sequencing techniques targeting the 18S rRNA gene.

Results

Our results revealed that four dogs 9.3% (4/43) including one female and three male dogs were infected with Babesia. All four Babesia-infected dogs were confirmed B. canis by the molecular-based method. Sequence alignments comparison of the B. canis genotypes A and B, it was revealed that all B. canis isolates belonged to genotype B.

Conclusion

This study provides essential data for subsequently define the critical importance of the molecular studies in management and prevention of the canine babesiosis in Iran.

Systemic inflammatory response syndrome in dogs naturally infected with Babesia canis: Association with the parasite load and host factors

The common signs of canine babesiosis caused by an infection with Babesia canis are fever, anorexia, lethargy, pulse alterations, anemia, and occasionally mild icterus. Dogs with these clinical signs can be divided into two groups: those with acute-phase reaction and those with systemic inflammatory response syndrome (SIRS). Factors associated with the occurrence of SIRS in canine babesiosis have not been thoroughly researched. This article outlines a cross-sectional study of 54 client-owned dogs with an acute B. canis infection, and evaluates the differences in age, gender, laboratory findings, parasite load, and seroreactivity against B. canis between the SIRS and the SIRS-free dogs. We have analyzed a complete blood count, serum biochemistry, serum amyloid A, ceruloplasmin, paraoxonase-1, serology, and PCR testing using standard methodologies. The frequency of SIRS among the investigated dogs reached 0.59. Male dogs and those seronegative against B. canis, were more frequent in the SIRS group, whilst age and parasite load could not be associated with the presence of SIRS. Dogs with SIRS had a lower count of total leukocytes, neutrophils, lymphocytes, and monocytes, and a lower concentration of iron and bilirubin compared with SIRS-free dogs. No significant differences in the concentration of acute-phase proteins have been noticed to exist between the groups of dogs. Further, the seronegative dogs had a lower count of lymphocytes and monocytes and a higher parasite load than the seroreactive dogs. Multivariate logistic regression analysis has identified leukopenia (<6 × 10⁹/L) and monocytopenia (<0.2 × 10⁹/L) as independent associates of SIRS in the investigated dogs, thus implying that these routine tests could be used as reliable markers for SIRS.

Lipid hijacking: a unifying theme in vector-borne diseases

Vector-borne illnesses comprise a significant portion of human maladies, representing 17% of global infections. Transmission of vector-borne pathogens to mammals primarily occurs by hematophagous arthropods. It is speculated that blood may provide a unique environment that aids in the replication and pathogenesis of these microbes. Lipids and their derivatives are one component enriched in blood and are essential for microbial survival. For instance, the malarial parasite Plasmodium falciparum and the Lyme disease spirochete Borrelia burgdorferi, among others, have been shown to scavenge and manipulate host lipids for structural support, metabolism, replication, immune evasion, and disease severity. In this Review, we will explore the importance of lipid hijacking for the growth and persistence of these microbes in both mammalian hosts and arthropod vectors.

Focus on Common Small Animal Vector-Borne Diseases in Central and Southeastern Europe

Vector-borne diseases are one of the main causes of morbidity and mortality in small animals in Europe. Many of these diseases are well-known among veterinary practitioners and some of them are called emerging diseases as prevalence, temporal and spatial distribution seem to increase in Europe. The number of newly recognized pathogens, transmitted by a variety of arthropod vectors, that are relevant for dogs and cats, is also increasing every year. The prevalence among infected vectors and hosts is a hot topic in veterinary science throughout the entire continent, as well as the development of efficient diagnostic procedures, therapy and prophylactic measures. Companion animal vector-borne diseases comprise a large group of pathogens including viruses, bacteria, protozoa and helminths. These pathogens are mainly transmitted by bloodsucking arthropods (ticks, fleas, mosquitos, sand flies), and more seldom by direct transmission between vertebrate hosts. Vector prevalence and activity is influenced by local climate conditions, host species density, changes in landscape and land use. Human parameters such as poverty and migration affect the use of prophylactic measures against pathogen transmission and infection as well as increasing the zoonotic risk to introducing pathogens by infected humans. Small animal associated factors such as pet trade and pet travel spread infection and certain vectors such as ticks and fleas. All these factors pose several complex and significant challenges for veterinarians in clinical practice to decide on efficient laboratory work-up and constructive diagnostic procedures.

Evidence of acute phase reaction in asymptomatic dogs naturally infected with Babesia canis

Asymptomatic outdoor dogs can be carriers of Babesia canis, but data describing the development of an acute phase response (APR) are not available. We hypothesised that these dogs have a moderate APR that could be detected by hematological and biochemical changes. Two groups of Babesia-exposed dogs were represented by nine B. canis PCR-positive and twenty B. canis PCR-negative, seroreactive dogs. The control group consisted of ten Babesia-naïve dogs. Serum amyloid A (SAA), paraoxonase-1 (PON-1), complete blood count, and biochemistry parameters were analysed by standard methodologies. Protein and lipoprotein fractions were separated using agarose gel electrophoresis (GE), and the dominant diameters of lipoproteins were assessed on gradient GE. Results were evaluated using non-parametric tests and the Receiver Operating Characteristic curve. SAA (median 39.0 μg/mL, range 2.2-48.8 μg/mL), total protein (median 74.7 g/L, range 57.1-98.3 g/L) and the dominant diameter of α-lipoproteins (median 13.31 nm, range 12.09-14.17 nm) in B. canis PCR-positive dogs were higher relative to dogs in the control group or dogs that were PCR-negative but seroreactive (p < 0.001 for both groups). Mild to moderate anemia (4/29), thrombocytopenia (7/29), and leukocyte counts that were close to the upper limit of the reference range were encountered in both Babesia-exposed groups. When compared to controls, Babesia-exposed dogs displayed decreased a PON-1 activity and protein GE pattern consistent with low-grade chronic inflammation (p < 0.001 for both groups). Dogs with detectable amounts of B. canis DNA in blood contain increased levels of SAA and total protein along with α-lipoproteins that display an increased diameter relative to those dogs with positive Babesia serology but undetectable levels of B. canis DNA in blood.

Evaluation of Serum Apolipoprotein A1 in Canine Sepsis

Decreased serum apolipoprotein A1 (Apo-A1) concentration is associated with mortality in human sepsis. The diagnostic and prognostic role of serum Apo-A1 concentrations in canine sepsis was evaluated. Serum samples from septic dogs (n = 91) and healthy controls (n = 15) were retrospectively analyzed. According to the sepsis origin, four categories were identified: parvoviral enteritis (n = 26), pyometra (n = 20), septic peritonitis (n = 19), and miscellanea (n = 26). The canine acute patient physiologic and laboratory evaluation fast score (APPLE_fast), serum C-reactive protein (CRP) and albumin concentrations were reviewed in all enrolled dogs. Increased CRP (252.6 ± 119.2 mg/L; Reference Interval: 0–8.5 mg/L) and significant lower serum albumin and Apo-A1 concentrations were documented in dogs with sepsis (22.8 ± 5.3 g/L and 1.17 ± 0.27 g/L, respectively) compared to healthy ones (33.1 ± 2.5 g/L and 1.32 ± 0.05 g/L, respectively) (P < 0.0001). According to the origin of sepsis, only the subgroup of dogs with septic peritonitis had significantly lower Apo-A1 (1.03 ± 0.26 g/L) concentrations compared to healthy dogs (P < 0.001). No significant differences were found in serum albumin and CRP concentrations, and in APPLE_fast score values among the different subgroups of sepsis. Diagnosis of septic peritonitis was associated with a higher frequency of death (P = 0.006). In septic dogs, significant lower Apo-A1 concentrations were detected in non-survivors (1.02 ± 0.28 g/L; n = 27) compared to survivors (1.23 ± 0.24 g/L; n = 64; P = 0.0007). Moreover, significant higher values of the APPLE_fast score were calculated in non-survivors (26 ± 4; n = 19) compared to survivors (23 ± 4; n = 51) (P = 0.0114). According to the area under the ROC curve analysis, Apo-A1 <96 mg/dl had a fair accuracy (AUC = 0.72) to correctly predict mortality (P = 0.0004). Apo-A1 might support a diagnosis of canine septic peritonitis with a potential prognostic significance. Further prospective studies are warranted.

Association of acute Babesia canis infection and serum lipid, lipoprotein, and apoprotein concentrations in dogs

BACKGROUND

Babesia canis infection induces a marked acute phase response (APR) that might be associated with alteration in lipid and lipoprotein metabolism and disease prognosis.

HYPOTHESIS

Dogs with B. canis-induced APR develop dyslipidemia with altered lipoprotein concentration and morphology.

ANIMALS

Twenty-nine client-owned dogs with acute B. canis infection and 10 clinically healthy control dogs.

METHODS

Observational cross-sectional study. Serum amyloid A (SAA) was measured using ELISA. Cholesterol, phospholipids, and triglycerides were determined biochemically. Lipoproteins were separated using agarose gel electrophoresis. Lipoprotein diameter was assessed by polyacrylamide gradient gel electrophoresis; correlation with ApoA-1 (radioimmunoassay) and SAA was determined.

RESULTS

Dogs with B. canis infection had a marked APR (median SAA, 168.3 μg/mL; range, 98.1-716.2 μg/mL) compared with controls (3.2 μg/mL, 2.0-4.2 μg/mL) (P < .001). Dogs with B. canis infection had significantly lower median cholesterol (4.79 mmol/L, 1.89-7.64 mmol/L versus 6.15 mmol/L, 4.2-7.4 mmol/L) (P = .02), phospholipid (4.64 mmol/L, 2.6-6.6 mmol/L versus 5.72 mmol/L, 4.68-7.0 mmol/L) (P = .02), and α-lipoproteins (77.5%, 27.7%-93.5% versus 89.2%, 75.1%-93.5%) (P = .04), and higher ApoA-1 (1.36 U, 0.8-2.56 U versus 0.95 U, 0.73-1.54 U) concentrations (P = .02). Serum amyloid A correlated with high-density lipoproteins (HDLs) diameter (rho = .43; P = .03) and ApoA-1 (rho = .63, P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Major changes associated with B. canis-induced APR in dogs are related to concentration, composition, and morphology of HDL particles pointing to an altered reverse cholesterol transport. Parallel ApoA-1 and SAA concentration increase is a unique still unexplained pathophysiological finding.