Utility of cardiac biomarkers during adulticide treatment of heartworm disease (Dirofilaria immitis) in dogs

Analytical quality assessment and method comparison of two immunoassays for the measurement of serum cardiac Troponin I in dogs and cats

BACKGROUND

Cardiac troponin I (cTnI) is a sensitive and specific biomarker for myocardial injury. Validation of point-of-care (POC) analyzers for cTnI measurement is valuable to the critical care setting, in which rapid results can facilitate prompt diagnoses. An immunoassay for detecting cTnI is available for the POC AIA-360 analyzer (Tosoh Bioscience), but this has not been validated using canine and feline serum.

OBJECTIVES

The objectives were (a) to determine precision, accuracy, and linearity of cTnI measurement using the AIA-360 immunoassay in pooled canine and feline samples, and (b) to compare results for individual canine and feline samples with those obtained using a reference chemiluminescence method (Immulite 1000, Siemens).

METHODS

Intra- and inter-assay repeatability was determined using pooled canine and feline samples, and the coefficient of variation (CV) was calculated for each. Pooled samples were also serially diluted to assess linearity. A modified spike and recovery analysis was performed by mixing pooled samples with different concentrations. Bland-Altman and Deming regression analyses were used to determine bias for individual samples, and the total observed error (TE_obs ) was calculated.

RESULTS

Coefficient of variation values were well within the required maximum of 20%. Linearity was demonstrated over the range of samples tested, and the recovery study showed minimal proportional inaccuracies. Although the correlation between the analyzers was excellent, there was a large mean bias due to relative proportional bias. Total observed error consequently exceeded the total allowable error (TE_A ).

CONCLUSION

Although, in most respects, the analyzer demonstrated adequate performance, pronounced bias contributed to the large TE_obs , indicating a requirement for analyzer-specific reference intervals.

Cardiopulmonary and inflammatory biomarkers in heartworm disease

In heartworm disease, several biomarkers of cardiopulmonary injury and inflammatory activity have been studied during the recent years. D-dimer is a fibrin degradation product present after a clot is degraded, which has been reported to provide support for the diagnosis of pulmonary thromboembolism in heartworm disease. Furthermore, concentrations increment with increased disease severity and during the adulticide treatment. This increase in concentration has proved to be valuable. Cardiac biomarkers troponin I, myoglobin and NT-proBNP demonstrated presence of myocardial injury and heart failure, especially in chronic infections, which in some cases, slightly improve after the adulticide treatment. An acute phase response in dogs with Dirofilaria immitis, characterized by variations of acute phase proteins (APP), has been reported, indicating inflammatory processes that could contribute to disease progression. Among them, C-reactive protein (CRP) increases according to the severity of the disease; and a strong correlation between pulmonary hypertension and CRP has been observed. In cats, little work has been done to ascertain the utility of these biomarkers in feline heartworm; the only published study in D. immitis–seropositive cats reported significantly higher concentrations in positive APP serum amyloid A, haptoglobin and ceruloplasmin.

Evaluation of cardiopulmonary and inflammatory markers in dogs with heartworm infection during treatment with the 2014 American Heartworm Society recommended treatment protocol

Background

Heartworm disease in dogs is a life-threatening parasitic disease. Although adulticide treatment with melarsomine has been proven to be the most effective, complications associated with adulticide treatment are major concerns for clinicians.

Methods

This study evaluated the change in levels of D-dimer, interleukin-6, C-reactive protein and cardiac troponin I in 12 dogs with different severities of heartworm infection treated by the American Heartworm Society (AHS) recommended protocol during the treatment period. The serum levels of several markers were measured on the day of diagnosis (T-60), before the initiation of melarsomine therapy (T0), 1 day after the first injection (T1), 1 week after the first injection (T7), 1 month after the first injection (T30), 1 day after the second injection (T31), 1 day after the third injection (T32), 1 week after the third injection (T39), 1 month after the third injection (T62), 2 months after the third injection (T92), 3 months after the third injection (T122), and 6 months after the third injection (T182).

Results

The serum levels of these markers were significantly different at the test time point after melarsomine treatment and also differed significantly according to the stage of heartworm disease in the dogs.

Conclusion

This study found that monitoring of inflammatory and hemostatic markers in dogs with heartworm disease being treated with melarsomine might be beneficial in predicting the clinical outcomes and complications associated with melarsomine treatment.

Cardioprotective effect of Notch signaling on the development of myocardial infarction complicated by diabetes mellitus

The present study aimed to elucidate the role of Notch signaling in the development of myocardial infarction (MI) concomitant with diabetes in vivo and in vitro and evaluated the therapeutic effect of the Notch signaling in vitro. Streptozotocin-induced diabetic rats were subjected to 25 min of ischemia and 2 h of reperfusion. Cardiac troponin T (cTnT) and creatine kinase-MB (CK-MB) isoenzyme levels were detected. Infarct size was measured by 2,3,5-triphenyltetrazolium chloride staining. Myocardial apoptosis and fibrosis were examined by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and Masson Trichrome staining, respectively. The mRNA and protein levels of Notch signaling components, including Notch1, Notch4, Delta-like 1, Jagged1, Mastermind-like protein 1 and p300, were quantified by reverse transcription-quantitative polymerase chain reaction and western blotting analyses, respectively. H9c2 cells were treated with/without 33 mM high glucose (HG) and/or subjected to hypoxia in the presence/absence of Jagged1. Cell viability and apoptosis were determined by MTT assay and Annexin V-fluorescein isothiocyanate/propidium iodide assay. Levels of the Notch signaling pathway members were examined. The present findings revealed that diabetes elevated CK-MB and cTnT, increased infarct size, induced myocardial apoptosis and inhibited the Notch signaling pathway in vivo after ischemia/reperfusion. Ischemia/reperfusion augmented the severity of MI in diabetic rats. Furthermore, HG reduced cell viability and induced cell apoptosis in H9c2 cells after hypoxia exposure, which was inhibited by Jagged1. We also found that HG inhibited Notch signaling in H9c2 cells after hypoxia, whereas Jagged1 exerted its cardioprotective effect on hypoxic injury (in HG environments or not) by activating the Notch signaling pathway. In conclusion, these findings suggest that diabetes promoted the progression of MI in vivo and in vitro via the inhibition of the Notch signaling pathway. Jagged1 may protect against MI in in vitro models by activating Notch signaling.

Evaluation of cardiopulmonary and inflammatory markers in dogs with heartworm infection treated using the slow kill method

This study evaluated the changes in the levels of cardiac, hemostatic, and inflammatory biomarkers in 12 dogs with different severities of heartworm infection treated using the slow kill protocol, consisting of 6-10μg/kg of ivermectin and 10mg/kg of doxycycline combination. The serum levels of cardiac troponin-I, D-dimer, C-reactive protein, and interleukin-6 were measured on the day of diagnosis (D0), after termination of doxycycline administration (D30), after termination of the slow kill treatment (D180), and 10 months after the initiation of therapy (D300). Heartworm antigenemia was cleared in 4/4 class I dogs, 3/4 class II dogs, and 1/4 class III dogs at the end of the therapy (D180), and in 4/4 class I, 4/4 class II, and 1/4 class III dogs at the end of the study (D300). The serum levels of the markers in class I dogs on the day of diagnosis (D0) were within the reference range, while the levels in class II and III dogs were above the reference range. Further, the serum levels of the markers in all dogs decreased significantly at the end of the study (D300), although some markers in class III dogs remained at pathological levels. This study revealed that the slow kill method should be used only as an alternative therapeutic protocol for dogs with low worm burden (class I and II). As the slow kill method alone may not effectively reduce all pathological changes in dogs with heavy worm burden and severe clinical signs (class III), adjuvant therapies including steroids and anti-thromboembolics should be used to minimize the risk of complications.

Cardiac Troponins in Dogs and Cats

Cardiac troponins are sensitive and specific markers of myocardial injury. The troponin concentration can be thought of as a quantitative measure of the degree of injury sustained by the heart, however, it provides no information on the cause of injury or the mechanism of troponin release. Conventionally, the cardiac troponins have been used for diagnosis of acute myocardial infarction in humans and have become the gold standard biomarkers for this indication. They have become increasingly recognized as an objective measure of cardiomyocyte status in both cardiac and noncardiac disease, supplying additional information to that provided by echocardiography and ECG. Injury to cardiomyocytes can occur through a variety of mechanisms with subsequent release of troponins. Independent of the underlying disease or the mechanism of troponin release, the presence of myocardial injury is associated with an increased risk of death. As increasingly sensitive assays are introduced, the frequent occurrence of myocardial injury is becoming apparent, and our understanding of its causes and importance is constantly evolving. Presently troponins are valuable for detecting a subgroup of patients with higher risk of death. Future research is needed to clarify whether troponins can serve as monitoring tools guiding treatment, whether administering more aggressive treatment to patients with evidence of myocardial injury is beneficial, and whether normalizing of troponin concentrations in patients presenting with evidence of myocardial injury is associated with reduced risk of death.

Puerarin attenuates severe burn-induced acute myocardial injury in rats

BACKGROUND

Puerarin, the main isoflavone glycoside extracted from the root of Pueraria lobata, is widely prescribed for patients with cardiovascular disorders in China. This study investigates the effect of puerarin on severe burn-induced acute myocardial injury in rats and its underlying mechanisms.

MATERIALS AND METHODS

Healthy adult Wistar rats were divided into three groups: (1) sham group, sham burn treatment; (2) burn group, third-degree burns over 30% of the total body surface area (TBSA) with lactated Ringer's solution for resuscitation; and (3) burn plus puerarin group, third-degree burns over 30% of TBSA with lactated Ringer's solution containing puerarin for resuscitation. The burned animals were sacrificed at 1, 3, 6, 12, and 24 h after burn injury. Myocardial injury was evaluated by analyzing serum creatine kinase MB fraction (CK-MB) activity and cardiac troponin T (cTNT) level. Changes in cardiomyocyte ultrastructure were also determined using a transmission electron microscope. Tumor necrosis factor (TNF)-α concentration in serum was measured by radioimmunoassay. Cardiac myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were measured to determine neutrophil infiltration and oxidative stress in the heart, respectively. The expression of p38 mitogen-activated protein (MAP) kinase in the heart was determined by Western blot analysis.

RESULTS

After the 30% TBSA full-thickness burn injury, serum CK-MB activities and cTnT levels increased markedly, both of which were significantly decreased by the puerarin treatment. The level of serum TNF-α concentration in burn group at each time-point was obviously higher than those in sham group (1.09±0.09 ng/ml), and it reached the peak value at 12 h post burn. Burn trauma also resulted in worsen ultrastructural condition, elevated MPO activity and MDA content in heart tissue, and a significant activation of cardiac p38 MAP kinase. Administration of puerarin improved the ultrastructural changes in cardiomyocytes, decreased TNF-α concentration in serum as well as suppressed cardiac MPO activity and reduced MDA content, and abolished the activation of p38 MAP kinase in heart tissue after severe burn.

CONCLUSIONS

These results suggest that puerarin attenuates inflammatory responses, reduces neutrophil infiltration and oxidative stress in the heart, and protects against acute myocardial injury induced by severe burn.

Acute phase protein response in heartworm-infected dogs after adulticide treatment

During the adulticide treatment of Dirofilaria immitis the worms die releasing fragments of parasites and causing pulmonary thromboembolisms which could exacerbate the clinical condition. To determine the utility of acute phase proteins (APPs) to monitor the progression of the treatment, different positive [C-reactive protein (CRP), haptoglobin (hp)] and negative [albumin, paraoxonase-1(PON-1)] APPs were measured in 15 heartworm-infected dogs (5 with high and 10 with low parasite burden) following adulticide treatment. The results showed increased concentrations of CRP, decreased concentrations of haptoglobin and PON-1 in infected dogs before starting the treatment. Progressive but not significant increases were observed in PON-1 activity and albumin concentration along the treatment. After the treatment with doxycycline and ivermectine a decrease in CRP and Hp levels was experienced, which could reflect a reduction of the vascular inflammation caused by the elimination of Wolbachia and reduction of microfilariae. Fifteen days after the first melarsomine injection, marked increases in CRP and Hp were observed, which could be due to pulmonary inflammation and thromboembolism caused by the post-adulticide death of the worms. This increase was greater in dogs with high parasite burden. As the pathology disappeared, there was an improvement in the concentrations of CRP and Hp, returning into reference values in dogs with low parasite burden at the end of the treatment. The measurement of CRP and Hp could be a resource of support to evaluate the magnitude of the post-adulticide complications during the adulticide treatment of D. immitis.

Cardiopulmonary and inflammatory biomarkers in the assessment of the severity of canine dirofilariosis

The prognosis and success of adulticide treatment depends on the baseline severity of infection with Dirofilaria immitis in dogs and can influence the therapeutic protocol to choose. A study was conducted to assess the utility of the cardiopulmonary biomarkers N-terminal of the prohormone brain natriuretic peptide (NT-proBNP), cardiac troponin I (cTnI), myoglobin, and D-dimer, as well as the biomarker of inflammation C-reactive protein (CRP) to evaluate the severity of canine heartworm disease in different stages. Serum samples were collected from 20 heartworm-infected dogs for measurement of these biomarkers. Dogs were assigned to four groups (n=5/group) according to the severity of the disease: Class I and Class II dogs showed concentrations of biomarkers generally within normal ranges for healthy dogs, except CRP in dogs classified as Class II, which showed values slightly above laboratory reference values (19.46±5.69mg/l). Dogs of Class III showed elevated levels of NT-proBNP (1220.12±465.18pmol/l) (p<0.05), cTnI (0.99±0.39ng/ml), CRP (33.98±7.99mg/l) (p<0.05), and 40% of these dogs (2/5) presented pathological values of D-dimer and myoglobin (p<0.05). Dogs of Class IV (caval syndrome) presented elevated levels of NT-proBNP (>2530.8pmol/l), cTnI (1.99±0.32ng/ml), and CRP (80.24±47.69mg/l); all Class IV dogs showed pathological elevations of D-dimer (0.81±0.46ng/ml), and 60% (3/5) of these dogs showed pathological elevations of myoglobin (significant elevations [p<0.05] for all biomarkers with respect to reference values and values for dogs in Classes I, II, and III). In canine heartworm disease, chronic presence of D. immitis causes a proliferative endoarteritis, thromboembolisms, pulmonary hypertension, and right-sided congestive heart failure. As the severity of the disease worsens, serum values of cTnI, myoglobin, and NT-proBNP increase, indicating significant cardiac damage. The finding of pathological concentrations of D-dimer suggests the presence of thromboembolism and/or disseminated intravascular coagulation. CRP increases according to the severity of the disease, indicating inflammatory processes that could contribute to the progression of the disease. These preliminary results demonstrate the utility of cardiopulmonary and inflammation biomarkers to assist in the establishment of the severity of canine heartworm disease.

Evaluation of cardiopulmonary biomarkers during classic adulticide treatment versus the American Heartworm Society recommended treatment protocol in dogs infected by Dirofilaria immitis

Adulticide treatment of dogs with canine heartworm disease causes the death of the adult Dirofilaria immitis lodged in the vascular system of the host. During the death of the worms, pulmonary thromboembolisms (PTE), pulmonary inflammation, congestive heart failure, or renal disease are possible consequences. The aim of this study was to evaluate cardiopulmonary biomarkers and renal parameters during adulticide treatment of canine heartworm to compare the classic two-injection treatment protocol versus the American Heartworm Society (AHS) recommended protocol. Fourteen heartworm-infected dogs with high parasite burdens were divided in three groups and allocated to adulticide protocols as follows: Group A (n=5) was treated with the classic two-injection protocol; group B (n=5) was treated using the AHS recommended protocol, and group C (n=4) was treated as for group B but received diminishing anti-inflammatory doses of prednisone. To assess cardiorespiratory status, cardiac troponin I (cTnI), myoglobin, and D-dimer were measured. Renal function was evaluated by measuring urea, creatinine, and urine protein:creatinine (UP:C). Serum and urine samples were collected day 0 (day of diagnosis), 7 and 14 days after the first dose of adulticide, and 1 month after the last adulticide injection. Dogs that received classic treatment presented pathologic concentrations of D-dimer more frequently and showed higher average D-dimer levels, which may indicate the presence of more severe PTE. Group C showed the highest levels of D-dimer during treatment, which may be due to an exacerbation of PTE caused by the administration of prednisone. CTnI and myoglobin values remained above reference values in all groups during the study but reached the lowest values 1 month after the last injection. Levels of urea and creatinine were within normal ranges in all groups, and 28.5% of the dogs were proteinuric on day 0, progressing to better UP:C values at the end of the treatment, except in group A. The results of this study justify the treatment of canine heartworm disease using the AHS recommended adulticide guidelines and recommends re-evaluation of the role of glucocorticosteroids in the prevention and treatment of PTE.