Avaliação das alterações hemostáticas e do risco tromboembólico em cães com AHIM / Evaluation of hemostatic abnormalities and thromboembolic risk in dogs with IMHA

A anemia hemolítica imuno-mediada (AHIM) é a causa mais comum dentre as anemias hemolíticas e a doença imuno-mediada de maior prevalência em cães, incluindo causas primárias e secundárias. As AHIM tem sido associadas a estados de hipercoagulabilidade, sendo o tromboembolismo a complicação mais comum. Este estudo teve como objetivo correlacionar as possíveis alterações hemostáticas e o risco tromboembólico nas AHIM e nas anemias por outras etiologias. Para tanto, foram selecionados 76 cães anêmicos (hematócrito ≤ 20%) somados ao menos um sinal clínico comumente associado à AHIM ou possuir pré-disposição racial. Foram realizados os seguintes testes para os animais selecionados: teste de citometria de fluxo e avaliação do perfil hemostático (contagem de plaquetas, TP, TTPA, TT, AT, PDF e Dímeros D); além de hemograma com contagem de reticulócitos, pesquisa de hematozoários em sangue periférico, PCR para Ehrlichia sp. e sorologia para leptospirose. 59 cães foram positivos para AHIM. O estado tromboembólico foi caracterizado pela presença de alteração em três ou mais testes do perfil hemostático. 74,6% casos de AHIM foram atribuídos às doenças infecciosas, sendo em sua maioria associados à Ehrlichia sp. (88,6%). 72,1% apresentaram trombocitopenia e 57,6% apresentaram anemia regenerativa com valores significativamente maiores de metarrubrícitos e contagem de reticulócitos. Não houve diferença estatística entre os grupos de cães anêmicos (positivos e negativos para AHIM). Os cães anêmicos apresentaram valores médios maiores de TTPA e menores de AT e contagem de plaquetas quando comparados aos cães saudáveis (p < 0,05). 25 cães positivos e sete negativos apresentaram estado tromboembólico. A especificidade de PDF foi menor (30,2%) quando comparada outros estudos. A escolha da classe de Ig não interfere no diagnóstico de AHIM...

Immune-mediated hemolytic anemia (IMHA) is the most common cause of hemolytic anemia and the most prevalent immune-mediated disease in dogs, which is classified in primary or secondary. IMHA has been associated with hypercoagulability state and thromboembolism has been referred as the most common complication. The purpose of this study was to correlate the possibility of hemostatic abnormalities and the thromboembolic risk in IMHA and in anemias of other etiologies. 76 dogs were selected, all exhibiting hematocrit lower than 20% and at least one clinical sign commonly associated with IMHA or breed predisposition. These dogs were tested for IMHA by flow cytometry. Hemostatic tests (platelet count, PT, APTT, TT, AT, PDF and D-dimer) as well as CBC, reticulocyte count, blood parasite search in peripheral blood smear, Ehrlichia sp. and leptospirosis tests were performed in all dogs. 59 dogs were positive for IMHA. The thromboembolic risk was characterized by the presence of three or more changes in the tests of the hemostatic profile. 74.6% cases of IMHA were attributed to infectious diseases and was mostly associated with Ehrlichia sp. (88.6%). 72.1% of dogs had thrombocytopenia and 57.6% had regenerative anemia with significantly higher values of metarubricyte and reticulocyte count. There were no significant changes between two anemic groups (positive and negative for IMHA). Anemic dogs had higher APTT mean value and lower AT and platelet counts mean values than the control group (p<0.05). 25 dogs with IMHA and seven dogs without IHMA had thromboembolic state. The specificity of PDF was lower (30.2%) than previous studies. The choice of the Ig class does not affect the diagnosis of IMHA...

Paracoccidioides brasiliensis interferes on dendritic cells maturation by inhibiting PGE2 production.

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil, whose etiologic agent is the thermodimorphic fungus of the genus Paracoccidioides, comprising cryptic species of Paracoccidioides brasiliensis, S1, PS2, PS3 and Paracoccidioides lutzii. The mechanisms involved in the initial interaction of the fungus with cells of the innate immune response, as dendritic cells (DCs), deserve to be studied. Prostaglandins (PGs) are eicosanoids that play an important role in modulating functions of immune cells including DCs. Here we found that human immature DCs derived from the differentiation of monocytes cultured with GM-CSF and IL-4 release substantial concentrations of PGE2, which, however, were significantly inhibited after challenge with P. brasiliensis. In vitro blocking of pattern recognition receptors (PRRs) by monoclonal antibodies showed the involvement of mannose receptor (MR) in PGE2 inhibition by the fungus. In addition, phenotyping assays showed that after challenge with the fungus, DCs do not change their phenotype of immature cells to mature ones, as well as do not produce IL-12 p70 or adequate concentrations of TNF-α. Assays using exogenous PGE2 confirmed an association between PGE2 inhibition and failure of cells to phenotypically mature in response to P. brasiliensis. We conclude that a P. brasiliensis evasion mechanism exists associated to a dysregulation on DC maturation. These findings may provide novel information for the understanding of the complex interplay between the host and this fungus.