[Levels of inflammatory cytokines and plasma cortisol in respiratory syncytial virus bronchiolitis]. / Aumento de interleuquinas proinflamatorias y de cortisol plasmático en bronquiolitis por virus respiratorio sincicial: relación con la gravedad de la infección.

BACKGROUND: An increased inflammatory innate response may play a role in pathogenesis of respiratory syncytial virus (RSV) infection. AIM: To quantify pro-inflammatory cytokines (IL-6-IL-8, ÍL-2-P and TNF-a) in nasopharyngeal aspirate (NPA) and plasma, and plasma cortisol in previously healthy infants with RSV bronchiolitis. PATIENTS AND METHODS: We studied 49 infants aged less than one year of age with RSV bronchiolitis and 25 healthy controls. Severity was defined using a previously described modified score. We quantified interleukins in NPA and plasma by flow cytometry and plasma cortisol by radioimmunoanalysis. RESULTS: Among patients with RSV bronchiolitis, 25 were classified as severe and 24 as moderate or mild. Significantly higher levels of IL-6 and IL-8 in NPA and plasma and IL-lfi in NPA were found in children classified as severe, when compared to those with moderate or mild disease and controls. There was a positive correlation between IL-6 and cortisol in plasma (r = 0,55; p < 0,0001) and both were correlated with the severity of the disease. CONCLUSIONS: RSV bronchiolitis severity was associated with higher levéis of inflammatory interleukins and plasma cortisol.

Aumento de interleuquinas proinflamatorias y de cortisol plasmático en bronquiolitis por virus respiratorio sincicial: relación con la gravedad de la infección / Levels of inflammatory cytokines and plasma cortisol in respiratory syncytial virus bronchiolitis

Background: An increased inflammatory innate response may play a role in pathogenesis of respiratory syncytial virus (RSV) infection. Aim: To quantify pro-inflammatory cytokines (IL-6-IL-8, ÍL-2-P and TNF-a) in nasopharyngeal aspirate (NPA) and plasma, and plasma cortisol in previously healthy infants with RSV bronchiolitis. Patients and Methods: We studied 49 infants aged less than one year of age with RSV bronchiolitis and 25 healthy controls. Severity was defined using a previously described modified score. We quantified interleukins in NPA and plasma by flow cytometry and plasma cortisol by radioimmunoanalysis. Results: Among patients with RSV bronchiolitis, 25 were classified as severe and 24 as moderate or mild. Significantly higher levels ofIL-6 and IL-8 in NPA and plasma and IL-lfi in NPA were found in children classified as severe, when compared to those with moderate or mild disease and controls. There was a positive correlation between IL-6 and cortisol in plasma (r = 0,55; p < 0,0001) and both were correlated with the severity of the disease. Conclusions: RSV bronchiolitis severity was associated with higher levéis of inflammatory interleukins and plasma cortisol.

Increased expression of the glucocorticoid receptor ß in infants with RSV bronchiolitis.

OBJECTIVES: The majority of studies on glucocorticoid treatment in respiratory syncytial virus (RSV) bronchiolitis concluded that there are no beneficial effects. We hypothesized that RSV-infected patients may have an increased glucocorticoid receptor (GR) ß expression, the isoform that is unable to bind cortisol and exert an antiinflammatory action. METHODS: By using real-time polymerase chain reaction, we studied the expression of α and ß GR in the peripheral blood mononuclear cells obtained from 49 RSV-infected infants (<1 year of age) with severe (n = 29) and mild to moderate (n = 20) illness. In plasma, we analyzed the level of cortisol by radioimmunoassay and inflammatory cytokines interleukin (IL)-10, IL-6, tumor necrosis factor-α, IL-1ß, IL-8, IL-12p70, IL-2, IL-4, IL-5, interferon-γ, and IL-17 by cytometric beads assay. Statistical analysis was performed by nonparametric analysis of variance. RESULTS: We found a significant increase of ß GR expression in patients with severe illness compared with those with mild disease (P < .001) and with a group of healthy controls (P < .01). The α:ß GR ratio decreased significantly in infants with severe disease compared with those with mild illness (P < .01) and with normal controls (P < .001). The expression of ß GR was positively correlated with the clinical score of severity (r = .54; P < .0001). CONCLUSIONS: The decrease of the α:ß GR ratio by an increase of ß receptors expression is related to illness severity and may partly explain the insensitivity to corticoid treatment in RSV-infected infants. The increased expression of ß GR could be a marker of disease severity.

T helper 1/T helper 2 cytokine imbalance in respiratory syncytial virus infection is associated with increased endogenous plasma cortisol.

OBJECTIVE: Cellular immunity has classically been described as the defense mechanism for viral infections. The development of cellular or humoral immune responses will depend on a repertoire of cytokines produced by numerous cells, including CD4+ and CD8+ T cells. These lymphocytes can be subdivided into 2 subsets, T helper 1 (Th1) and Th2, on the basis of the cytokine profiles they synthesize. Type 1 T cells produce interferon gamma (IFN-gamma), an essential cytokine in the viral cell-mediated immune response. Th2 cells selectively produce interleukin 4 (IL-4) and IL-5 that participate in the development of humoral immunity and have a prominent role in immediate-type hypersensitivity. An imbalance in the Th1/Th2 cytokine immune response has been related to pathogenesis of the respiratory syncytial virus (RSV) bronchiolitis and to the severity of the infection. Glucocorticosteroids have a role in inhibiting the IFN-gamma response, acting directly on T cells or indirectly through IL-12. In this way, an increase in plasma cortisol would induce a decrease in the Th1 products with the imbalance between Th1/Th2 cytokines and a shift to Th2 response. We hypothesized that there is a relationship among endogenous cortisol response in acute RSV infection, severity of illness, and decreased Th1 cytokine response. METHODS: We studied 42 infants under 12 months of age during an acute RSV infection. Twenty-one infants with a median age of 6 months had a severe illness and required hospitalization, whereas 21 with mild diseases with a median age of 7 months were under ambulatory control. All of them had bronchial obstruction evidenced by wheezing and/or hyperinflation on chest radiograph and positive RSV antigen detected by indirect immunofluorescence in nasopharyngeal aspirates. The control group included 21 infants in good health matched by age and gender with median age of 6 months that required blood tests for minor surgery. They were evaluated during a non-RSV epidemic period. Heparinized blood was collected on enrollment from all participating children at 9 am for total leukocyte and differential cell count, determination of lymphocyte subsets, and for intracellular detection of cytokines in single cells; mononuclear cells were cultured to determine in the supernatant cytokine production. In addition, 1 mL of plasma was separated and kept frozen at -20 degrees C for cortisol assay. In the supernatant of the cultured peripheral blood mononuclear cells (PBMCs), we quantified IL-12, IFN-gamma, IL-4, IL-5, and IL-10. Lymphocyte phenotypes and CD4+ and CD8+ T cells with intracellular IL-4, IL-10, and IFN-gamma were analyzed by triple-color immunofluorescence of single cells on a FACScan flow cytometer. RESULTS: Infants with severe illness had significantly higher plasma cortisol levels than infants with mild disease, and in both groups of infected infants, those were higher than in the control group. A significantly decreased IL-12 and IFN-gamma production by PBMCs and a fall in the percentage of CD4+ T cells expressing IFN-gamma were observed only in the severely affected infants. IL-12 concentrations were 2 pg/mL in severe illness versus 13 pg/mL in mildly infected infants and 12 pg/mL in controls. PBMCs from infants with severe illness produced less IFN-gamma than mildly infected infants and than controls when compared with severe illness. No differences between the 3 groups of infants were observed during the acute phase of the disease for IL-4, IL-5, and IL-10. IL-12 and IFN-gamma production had an inverse correlation with plasma cortisol levels. During severe RSV bronchiolitis, infants developed lymphopenia, and significantly lower eosinophil counts and percentages and absolute counts of CD4+ and CD8+ T cells. Eighty days postinfection, all values had returned to normal levels. CONCLUSIONS: In this study, we demonstrate that during the acute phase of RSV infection, there is an increase in the level of plasma cortisol that is parallel to the decrease in IL-12 and IFN-gamma production. These findings suggest an association between increased plasma cortisol and a decreased Th1-type response. The increase in plasma cortisol was greater in infants with the more severe symptomatology in association with a lower level of IL-12 and IFN-gamma production. The potential causative role of endogenous cortisol in the imbalance of the Th1/Th2 response observed during severe RSV infection requires additional investigation. Our results suggest that the immunologic changes observed in the more severely ill patients may be partially explained by the increased levels of plasma cortisol. This finding should be taken into consideration when systemic steroids are prescribed to infants infected with the RSV because there is still controversy regarding the efficacy of systemic steroid use in severe bronchiolitis.