RESUMO
To better understand uterine inflammation in postpartum dairy cows we collected sequential cytobrush samples at 29-35 and at 49-55â¯d in milk (DIM). Based on the uterine cytology, cows were classified as Non-endometritic (nâ¯=â¯23; <18% neutrophils) or Endometritic (nâ¯=â¯12; ≥18% neutrophils) at 29-35 DIM and Non-endometritic (nâ¯=â¯17; <10% neutrophils) or Endometritic (nâ¯=â¯9; ≥10% neutrophils) at 49-55 DIM. Cows defined as Sham Controls (nâ¯=â¯6) were examined by vaginoscopy at 29-35 DIM and identified as Non-endometritic (<10% neutrophils) at 49-55 DIM. Cytokine gene expression in cytobrush samples was assessed using qRT-PCR. Sham Controls did not differ significantly (Pâ¯>â¯0.17) from Non-endometritic cows at 49-55 DIM and these data were combined (nâ¯=â¯23). Uterine cytology-based classification using the aforementioned thresholds effectively separated cows into groups with Endometritic cows having significantly higher expression of pro-inflammatory (interleukin (IL)-1α, IL-1ß, IL-6, IL-8, IL-17A CSF-1; Pâ¯<â¯0.01) and regulatory (IL-1RA and IL-10; Pâ¯<â¯0.03) cytokines, relative to Non-endometritic cows. Furthermore, Non-endometritic cows showed a significant decline (Pâ¯<â¯0.03) in the expression of pro-inflammatory (IL-1α, IL-6, IL-8) and regulatory (IL-10) cytokine genes as the postpartum period progressed; whereas Endometritic cows exhibited a sustained elevation in transcript abundance throughout the sample period for both pro-inflammatory and regulatory cytokine genes. Expression of transforming growth factor (TGF) genes was more complex with TGF-ß3 expression significantly (Pâ¯<â¯0.01) lower at 29-35 DIM and TGF-ß1 gene expression significantly (Pâ¯<â¯0.03) increased at 49-55 DIM in Endometritic versus Non-endometritic cows. Expression of TGF-ß2 gene was 2.7-fold higher (Pâ¯<â¯0.01) at 29-35 DIM in cows that remained Endometritic when compared to cows recovering by 49-55 DIM. Some Non-endometritic cows (nâ¯=â¯4) at 29-35 DIM were reclassified as Endometritic at 49-55 DIM. The sampling procedures at 29-35 DIM did not alter either the cellular response (Pâ¯>â¯0.43) or cytokine gene expression (Pâ¯>â¯0.17) at 49-55 DIM. In conclusion, normal uterine involution is characterized by a progressive decline in pro-inflammatory and regulatory cytokine gene expression, while cows with endometritis show a dysregulated inflammatory process characterized by a sustained elevation in pro-inflammatory and regulatory cytokine gene expression. This analysis also shows that decreased TGF-ß2 gene expression at 29-35 DIM may be an indicator of recovery from endometritis.
Assuntos
Doenças dos Bovinos/imunologia , Citocinas/metabolismo , Endometrite/veterinária , Útero/metabolismo , Animais , Bovinos , Doenças dos Bovinos/metabolismo , Citocinas/genética , Endometrite/imunologia , Endometrite/metabolismo , Feminino , Regulação da Expressão Gênica , Período Pós-Parto/imunologia , Período Pós-Parto/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Útero/patologiaRESUMO
Thirty postpartum cows (28 to 41 days in milk) without signs of clinical endometritis were categorized as inflammation-negative (N = 18) or subclinical endometritis-positive (N = 12) based on endometrial cytobrush cytology (> 18% polymorphonuclear cells; PMNs). Slides for cytology were prepared before the same cytobrush was transferred to a tube containing 1 mL Trizol reagent. Total RNA was extracted from each cytobrush sample and analysis of il6, il8, tnfα, and ßactin gene expression was performed using quantitative real-time polymerase chain reaction. Cytobrush sampling provided sufficient material to prepare cytosmears and extract high quality endometrial mRNA (mean = 0.96 µg RNA per sample). Cytokine expression varied between experimental groups with a 20-fold higher tnfα (P = 0.001), a 30-fold higher il6 (P = 0.01), and a greater than 50-fold higher il8 mRNA expression level (P = 0.0001) in subclinical endometritis-positive versus disease-negative cows. Regression analysis of gene expression levels (cycle threshold) versus PMN frequency showed that the frequency of PMNs in the cytosmear decreased by 3.3% (P = 0.000 01), 2.3% (P = 0.015), and 2.4% (P = 0.05) for each additional cycle threshold required to detect il8, il6, and tnfα gene expression, respectively. Expression of the individual cytokines was positively associated: il8 and il6 (P = 0.0001); il8 and tnfα (P = 0.000 01); and il6 and tnfα (P = 0.0002). In conclusion, the endometrial cytobrush technique was successfully used to obtain material for both cytology and RNA extraction, and il8 gene expression may be useful to predict endometrial inflammation.