Similar cytokine profiles in response to infection with respiratory syncytial virus type a and type B in the upper respiratory tract in infants.

Human respiratory syncytial virus (RSV) is the leading viral cause of severe respiratory illness in infants and young children worldwide. RSV isolates can be divided into 2 subgroups, type A and type B. Here, we compare for the first time the nasal profiles of 27 immune mediators in response to both viral subtypes in 14 children infected with RSV/A, 8 children infected with RSV/B, 11 children coinfected with RSV/A plus other respiratory viruses, and finally, 27 control children, all <2 years old. Our results evidence that children's infection with both RSV subtypes induces very similar profiles of immune mediators in the upper respiratory tract, characterized by the elevation of Th1 and Th2 cytokines, chemokines and growth factors. Interestingly, no major differences in the profiles of the immune mediators were found between the children infected exclusively with RSV/A and those infected with RSV/A plus other respiratory viruses.

Bermejo-Martin JF ，Tenorio A ，Ortiz de Lejarazu R ，Eiros JM ，Matías V ，Dominguez-Gil M ，Pino M ，Alonso A ，Blanco-Quiros A ，Arranz E ，Ardura J ... -  《-》

Respiratory syncytial virus and other respiratory viruses during the first 3 months of life promote a local TH2-like response.

Kristjansson S ，Bjarnarson SP ，Wennergren G ，Palsdottir AH ，Arnadottir T ，Haraldsson A ，Jonsdottir I ... -  《JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY》

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

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. 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. 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. 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.

Pinto RA ，Arredondo SM ，Bono MR ，Gaggero AA ，Díaz PV ... -  《-》

Moderate local and systemic respiratory syncytial virus-specific T-cell responses upon mild or subclinical RSV infection.

Respiratory syncytial virus (RSV) infections are a major cause of severe respiratory disease in infants. It has been shown that there is an increased frequency of childhood wheezing in ex-bronchiolitic preteen children. This was postulated to be mediated by a vigorous virus-specific Th2 response influencing the further development of the immune system. Little is known about the possible role of the immune response to clinically mild RSV infections in this respect. We have studied the RSV-specific cellular immune response in infants with a laboratory-confirmed RSV upper respiratory tract infection (URTI; n = 13, mean age 12 months, range 2-22 months) in comparison with infants with non-RSV mediated URTI (n = 9, mean age 9.3 months, range 4-18 months) or infants with severe RSV bronchiolitis (n = 11, mean age 2.3 months, range 1-6 months). RSV-specific cytokine-producing cells were enumerated using the ELISPOT method in peripheral blood mononuclear cells and nasal brush T-cells, collected during the acute and convalescent phase of the infection. Mixed Th1 (IFN-gamma) and Th2 (IL-4 and IL-13) responses were detected in all three groups. Frequencies of RSV-specific T-cells were lower in both URTI groups than in the RSV bronchiolitis group, and not significantly different between the RSV URTI and the non-RSV URTI group. The absence of vigorous virus-specific Th2 responses upon mild RSV infection does not support the hypothesis that these infections influence the development of the immune system and that they predispose for the development of atopic disease.

de Waal L ，Koopman LP ，van Benten IJ ，Brandenburg AH ，Mulder PG ，de Swart RL ，Fokkens WJ ，Neijens HJ ，Osterhaus AD ... -  《JOURNAL OF MEDICAL VIROLOGY》

Impaired immune response in severe human lower tract respiratory infection by respiratory syncytial virus.

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infection in infants. The immune response plays a leading role in the severity of the disease. We hypothesized that severe RSV disease is associated with an impaired immune response characterized by low circulating T lymphocytes and plasma cytokine concentrations. We evaluate the in vivo immune responses of previously healthy infants with their first proven RSV-acute lower respiratory infection that required hospitalization. According to the clinical severity, defined by using a strict scoring system, the in vivo immune response was compared through the analysis of plasma cytokine values and the phenotyping of peripheral blood lymphocyte and natural killer (NK) cells. Absolute blood cell counts of CD4+, CD8+, and CD19+ lymphocytes and NK cells were lower in subjects with RSV than in control infants. Lowest cell counts were observed in more severe RSV-infected infants. Significant low values were obtained in CD8+ lymphocytes (P = 0.03) and nonactive NK cells, that express CD94 antigen (P = 0.046). In contrast, activated NK cells that do not express CD94 molecules were significantly higher in RSV infected infants than in healthy controls (% of cells: P = 0.004). The interferon-gamma and tumor necrosis factor-alpha values in RSV infected patients were lower than in controls subjects. Interleukin-17 cytokine was not detected in healthy infants and the largest concentration was found in moderately ill patients as compared with severe cases (P = 0.033). RSV infection showed significantly higher interleukin-8 chemokine than in control infants (P = 0.024). We propose that severe RSV infection in very young infants is associated with poor blood proinflammatory cytokine production, low counts of CD8+ T cells and with a greater activity of a group of NK cells, that are independent of the major histocompatibility complex class Ib recognition system.

Larrañaga CL ，Ampuero SL ，Luchsinger VF ，Carrión FA ，Aguilar NV ，Morales PR ，Palomino MA ，Tapia LF ，Avendaño LF ... -  《-》