Since the definitive identification in 1995 of the bacterial endosymbiont
Wolbachia that resides in different tissues of the filarial worm
Dirofilaria immitis, there has been increasing interest to ...understand whether and what role it plays in the pathogenesis of and immune response to heartworm infection. The present study evaluated the effects of treatments on lung pathology in 20 beagle dogs experimentally infected with
D. immitis. Dogs in Group 1 were treated with doxycycline (10
mg/kg/day) orally from weeks 0–6, 10–12, 16–18, 22–26, and 28–34. Dogs in Group 2 served as infected, non-treated controls. Dogs in Group 3 were given doxycycline as described for Group 1 combined with weekly oral doses of ivermectin (6
mcg/kg) for 34 weeks and intramuscular (IM) melarsomine (2.5
mg/kg) at week 24, followed by two additional melarsomine injections 24
h apart 1 month later. Group 4 received only melarsomine as described for Group 3. Lung lesion criteria, scored by two independent blinded pathologists, included perivascular inflammation and endothelial proliferation. Doxycycline treatment alone had no effect on lesion scores, whereas the combination of doxycycline and ivermectin resulted in less severe perivascular inflammation. All lungs were evaluated for positive immunostaining for the
Wolbachia surface protein (WSP). Control dogs showed numerous thrombi, intense perivascular and interstitial inflammation and, occasionally, positive staining for WSP. Interestingly, dogs receiving doxycycline/ivermectin/melarsomine showed significantly less severe arterial lesions and the virtual absence of thrombi.
•Established cysts of Echinococcus granulosus in sheep are associated with CD3+ T cells.•Most established cysts are in the lung.•Foxp3+ cells make up part of the local inflammatory infiltrate.
Ovine ...hydatidosis (OH; Echinococcus granulosus) is endemic in several European countries surrounding the Mediterranean basin. There have been a limited number of studies aimed at evaluating the local immune response to established tissue cysts in the ovine host. In the present study, immunohistochemical analysis of lymphocyte populations surrounding established cysts showed a predominance of CD3+ T cells compared to CD79+ B cells. A percentage of infiltrating lymphocytes were also FoxP3+, suggesting that established ovine cysts may be protected from immune aggression through the suppressive action of T regulatory cells. The present study contributes to the understanding of local immune responses to ovine echinococcosis.
In a previous study, dogs experimentally infected with Dirofilaria immitis were treated with either ivermectin or doxycycline or a combination of both. The adulticide effect was significantly higher ...in the dogs treated with both drugs and was similar to that observed in dogs treated with melarsomine hydrochloride. In the present study, lung tissue samples from these dogs were evaluated for the presence of T regulatory (Foxp3+) cells by immunohistochemistry. Cells were enumerated for each dog in the four groups and compared with untreated controls. There was a significantly lower number of Treg cells in those dogs treated with a combination of both drugs when compared either to the control group or to the other groups treated with either drug alone or with melarsomine. These results suggest that successful adulticide effects of doxycycline and ivermectin are associated with a decrease in immune regulation towards the parasite.
Adulticide therapy in heartworm (
Dirofilaria immitis)-infected dogs can lead to thromboembolism, which can seriously compromise post-treatment health status. Lung pathology following adulticide ...therapy was evaluated in three groups of experimentally infected dogs. Group 1 was treated with doxycycline at 20
mg/kg per os once daily for 30 days post infection followed by an intramuscular injection of melarsomine dihydrochloride (2.5
mg/kg) at Week 12, followed 1 month later by two injections 24
h apart. Group 2 was treated as described for Group 1, with the addition of ivermectin at 6 mcg/kg given monthly per os for 24 weeks post-infection. Group 3 received melarsomine alone, as described above. All dogs were necropsied at Week 24 and lung pathology was evaluated. Lesion criteria included perivascular inflammation and endothelial proliferation. Lesions were scored by two independent pathologists who were blinded as to treatment. Results indicate that doxycycline treatment alone or combined with ivermectin had lower lesion scores than lungs from dogs who had received melarsomine alone. Dogs that received the combined doxycycline/ivermectin protocol and treated with adulticide showed less severe arterial lesions and the virtual absence of thrombi.
It has recently been reported that dogs affected by canine heartworm disease (Dirofilaria immitis) can show an increase in plasma levels of myoglobin and cardiac troponin I, two markers of ...muscle/myocardial injury. In order to determine if this increase is due to myocardial damage, the right ventricle of 24 naturally infected dogs was examined by routine histology and immunohistochemistry with anti-myoglobin and anti-cardiac troponin I antibodies. Microscopic lesions included necrosis and myocyte vacuolization, and were associated with loss of staining for one or both proteins. Results confirm that increased levels of myoglobin and cardiac troponin I are indicative of myocardial damage in dogs affected by heartworm disease.
It has been reported that dogs with heartworm disease (Dirofilaria immitis) show increased plasma levels of D-dimer, a fibrin degradation product present in the blood after a blood clot is degraded ...by fibrinolysis. In the present study the authors show that, in dogs with both experimental and natural infections with D. immitis, D-dimer deposits in lungs and kidneys are associated with pulmonary thromboembolism and microfilariemic status, as well as there was a clear association between increased plasma values of D-dimer and positive staining in immunohistochemistry. Results suggest that the monitoring of D-dimer levels in infected dogs could be useful in evaluating the presence of pulmonary thromboembolism in the lungs and that microfilariae may induce microthrombosis in kidneys, thus contributing to renal pathology.
A cat was presented with a history of vomiting, decreased appetite and weight loss. Abnormal findings were poor body condition, pale mucous membranes, dehydration and a palpable abdominal mass. ...Abdominal ultrasound showed lymph node enlargement, a mass of uncertain origin, thickening of the muscularis layer of the small bowel, focal thickening of the ileum with loss of layering and free peritoneal fluid. Cytology revealed a piogranulomatous infiltrate and numerous macrophages containing oval or round yeast-like cells 2 to 5 μm diameter with a central, spherical, lightly basophilic body surrounded by a clear halo, compatible with Histoplasma capsulatum, within the cytoplasm. Post-mortem examination revealed cavity effusions, granulomatous nodules in lungs, intestine and omentum, thickened intestinal walls and intestinal perforation. Staining with Grocott and immunohistochemistry (IHC) revealed numerous organisms within the granulomatous reaction. H. capsulatum has a worldwide distribution in temperate and subtropical climates. To the author's knowledge, this is the first report of feline histoplasmosis in Europe.
Cardiac Troponin I (cTnI) is a polypeptide involved in myocardial contraction and has been shown to be a highly sensitive biomarker of myocardial injury in humans.
Chronic myocardial ischemia was ...induced in eight adult sheep by anterior coronary artery legation. Forty-five days after coronary artery legation, sheep underwent autologous myoblasts implantation to the infarct area to improve local tissue regeneration. Blood samples were taken at regular intervals before and after the induced coronary ischemia and myoblast implantation and serum levels of cTnI were assessed with chemiluminescent immunodosage using a commercially available anti-human cTnI monoclonal antibody.
cTnI levels began to increase the day after coronary legation and after myoblast implantation and gradually recovered to physiological levels in the next 14 days. Furthermore, the commercial anti-human antibody was shown to completely cross react with the ovine polypeptide as well as with canine, swine and equine sera.
Feline immunodeficiency virus sustains an AIDS-like syndrome in cats, which is considered a relevant model for human AIDS. Under precise enrolment requirements, 30 naturally infected cats showing ...overt disease were included in a trial of low-dose, oral human interferon-α treatment. Twenty-four of them received 10
IU/Kg of human interferon-α and 6 placebo only on a daily basis under veterinary supervision. The low-dose human interferon-α treatment significantly prolonged the survival of virus-infected cats (
p
<
0.01) and brought to a rapid improvement of disease conditions in the infected hosts. Amelioration of clinical conditions was neither correlated with plasma viremia, nor with proviral load in leukocytes. A good survival of CD4+ T cells and a slow increase of CD8+ T cells were also observed in human interferon-α-treated cats. Interestingly, the improvement of the total leukocyte counts showed a much stronger correlation with the recovery from serious opportunistic infections. As shown in other models of low-dose interferon-α treatment, there was a rapid regression of overt immunopathological conditions in virus-infected cats. This hints at a major role of interferon-α in the control circuits of inflammatory cytokines, which was probably the very foundation of the improved clinical score and survival despite the unabated persistence of virus and virus-infected cells.
Intracellular bacteria in filarial nematodes were described as early as the 1970s, yet it was only with the work on Dirofilaria immitis, the agent of canine and feline heartworm disease, that these ...microorganisms were identified as belonging to Wolbachia, a genus known for encompassing bacteria infecting insects and other arthropods. The implications for the presence of intracellular bacteria in filarial nematodes is now the subject of intense research, particularly regarding their role in the immunology and pathogenesis of disease in infected humans and animals and as a possible target for therapy. Here, the authors report results on the immunohistochemical and immunogold staining of Wolbachia in D. immitis and Brugia pahangi using polyclonal antibodies raised against the recombinant Wolbachia surface protein (WSP). The bacteria were present in the lateral hypodermal chords of both male and female worms and in the reproductive tract of adult females (oocytes, morulae, microfilariae). In D. immitis and B. pahangi from animals treated with tetracycline, positive staining was observed in the lateral chords of adult males and females, but was absent from the oocytes and morulae. These results indicate that Wolbachia endosymbionts can be identified immunohistochemically with anti-WSP polyclonal antibodies, that their distribution matches that already described for Wolbachia of other filarial worms, and that antibiotic treatment may impede the vertical transmission of these bacteria. Unequivocal detection of Wolbachia is essential for the study of this symbiont, in particular to monitor the effects of antibiotic treatment on worms. The use of a specific marker for bacteria in their nematode hosts represents an extremely useful tool in evaluating the pathogenic role and the effect of antibiotic treatment on these potential targets in the control of filarial disease.
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