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Abstract Rationale Gap junctions are membrane channels formed by an array of connexins which links adjacent cells realizing an electro- metabolic synapse. Connexin-mediated communication is crucial in the regulation of cell growth, differentiation, and development. The activation and proliferation of phenotypically altered fibroblasts are central events in the pathogenesis of idiopathic pulmonary fibrosis. We sought to evaluate the role of connexin-43, the most abundant gap-junction subunit in the human lung, in the pathogenesis of this condition. Methods We investigated the transcription and protein expression of connexin-43 and the gap-junctional intercellular communication (GJIC) in 5 primary lung fibroblast lines derived from normal subjects (NF) and from 3 histologically proven IPF patients (FF). Results Here we show that connexin-43 mRNA was significantly reduced in FF as demonstrated by standard and quantitative RT-PCR. GJIC was functionally evaluated by means of flow-cytometry. In order to demonstrate that dye spreading was taking place through gap junctions, we used carbenoxolone as a pharmacological gap-junction blocker. Carbenoxolone specifically blocked GJIC in our system in a concentration dependent manner. FF showed a significantly reduced homologous GJIC compared to NF. Similarly, GJIC was significantly impaired in FF when a heterologous NF line was used as dye donor, suggesting a complete defect in GJIC of FF. Conclusion These results suggest a novel alteration in primary lung fibroblasts from IPF patients. The reduced Cx43 expression and the associated alteration in cell-to-cell communication may justify some of the known pathological characteristic of this devastating disease that still represents a challenge to the medical practice.

Abstract Background T lymphocytes are demonstrated to play an important role in several chronic pulmonary inflammatory diseases. In this study we provide evidence that human lung fibroblasts are capable of mutually interacting with T-lymphocytes leading to functionally significant responses by T-cells and fibroblasts. Methods Human lung fibroblast were co-cultured with PMA-ionomycin activated T-CD4 lymphocytes for 36 hours. Surface as well as intracellular proteins expression, relevant to fibroblasts and lymphocytes activation, were evaluated by means of flow cytometry and RT-PCR. Proliferative responses of T lymphocytes to concanavalin A were evaluated by the MTT assay. Results In lung fibroblasts, activated lymphocytes promote an increase of expression of cyclooxygenase-2 and ICAM-1, expressed as mean fluorescence intensity (MFI), from 5.4 ± 0.9 and 0.7 ± 0.15 to 9.1 ± 1.5 and 38.6 ± 7.8, respectively. Fibroblasts, in turn, induce a significant reduction of transcription and protein expression of CD69, LFA-1 and CD28 in activated lymphocytes and CD3 in resting lymphocytes. In activated T lymphocytes, LFA-1, CD28 and CD69 expression was 16.6 ± 0.7, 18.9 ± 1.9 and 6.6 ± 1.3, respectively, and was significantly reduced by fibroblasts to 9.4 ± 0.7, 9.4 ± 1.4 and 3.5 ± 1.0. CD3 expression in resting lymphocytes was 11.9 ± 1.4 and was significantly reduced by fibroblasts to 6.4 ± 1.1. Intracellular cytokines, TNF-alpha and IL-10, were evaluated in T lymphocytes. Co-incubation with fibroblasts reduced the number of TNF-alpha positive lymphocytes from 54,4% ± 6.12 to 30.8 ± 2.8, while IL-10 positive cells were unaffected. Finally, co-culture with fibroblasts significantly reduced Con A proliferative response of T lymphocytes, measured as MTT absorbance, from 0.24 ± 0.02 nm to 0.16 ± 0.02 nm. Interestingly, while the activation of fibroblasts is mediated by a soluble factor, a cognate interaction ICAM-1 mediated was demonstrated to be responsible for the modulation of LFA-1, CD28 and CD69. Conclusion Findings from this study suggest that fibroblasts play a role in the local regulation of the immune response, being able to modulate effector functions of cells recruited into sites of inflammation.

The role of eosinophils in the pathogenesis of allergic disorders has been established by several studies. Recently, it has been suggested that second-generation antihistamines, widely used to relieve allergic symptoms, may have anti-inflammatory effects. To assess the possible anti-inflammatory activity of fexofenadine, a selective H1-receptor antagonist, we evaluated its capacity to modulate the expression of adhesion molecules leukocyte function-associated antigen (LFA) 1 and intracellular adhesion molecule (ICAM) 1 on eosinophil surface and to induce apoptosis of eosinophils. To analyze the expression of adhesion molecules, eosinophils from healthy donors were cultured in the presence of interferon γ and tumor necrosis factor a with various concentrations of fexofenadine, incubated with monoclonal antibodies anti-ICAM-1 and LFA-1 and then analyzed by flow cytometry. To evaluate apoptosis of eosinophils, cells stimulated with interleukin-5, in the presence of different concentrations of fexofenadine, have been incubated with a phosphatidylserine-binding protein (annexin V) fluorescein isothiocyanate conjugated and then analyzed by flow cytometry. Apoptosis was evaluated as a percentage of annexin V+ cells. In this study, fexofenadine did not cause any significant changes in the expression of LFA-1 but was shown to be able to inhibit the expression of ICAM-1 at concentrations between 10-3 and 10-4 M. Moreover, concentrations of fexofenadine from 10-3 to 6 × 10-4 M induced a significant increment in the percentage of apoptotic cells. Our findings indicate the possibility of obtaining relevant anti-inflammatory pharmacologic effects, other than antihistamine activity, by fexofenadine, such as inhibition of ICAM-1 expression and induction of eosinophil apoptosis. [ABSTRACT FROM AUTHOR]

Background: T lymphocytes are demonstrated to play an important role in several chronic pulmonary inflammatory diseases. In this study we provide evidence that human lung fibroblasts are capable of mutually interacting with T-lymphocytes leading to functionally significant responses by T-cells and fibroblasts. Methods: Human lung fibroblast were co-cultured with PMA-ionomycin activated T-CD4 lymphocytes for 36 hours. Surface as well as intracellular proteins expression, relevant to fibroblasts and lymphocytes activation, were evaluated by means of flow cytometry and RT-PCR. Proliferative responses of T lymphocytes to concanavalin A were evaluated by the MTT assay. Results: In lung fibroblasts, activated lymphocytes promote an increase of expression of cyclooxygenase-2 and ICAM-1, expressed as mean fluorescence intensity (MFI), from 5.4 ± 0.9 and 0.7 ± 0.15 to 9.1 ± 1.5 and 38.6 ± 7.8, respectively. Fibroblasts, in turn, induce a significant reduction of transcription and protein expression of CD69, LFA-1 and CD28 in activated lymphocytes and CD3 in resting lymphocytes. In activated T lymphocytes, LFA-1, CD28 and CD69 expression was 16.6 ± 0.7, 18.9 ± 1.9 and 6.6 ± 1.3, respectively, and was significantly reduced by fibroblasts to 9.4 ± 0.7, 9.4 ± 1.4 and 3.5 ± 1.0. CD3 expression in resting lymphocytes was 11.9 ± 1.4 and was significantly reduced by fibroblasts to 6.4 ± 1.1. Intracellular cytokines, TNF-alpha and IL-10, were evaluated in T lymphocytes. Co-incubation with fibroblasts reduced the number of TNF-alpha positive lymphocytes from 54,4% ± 6.12 to 30.8 ± 2.8, while IL-10 positive cells were unaffected. Finally, co-culture with fibroblasts significantly reduced Con A proliferative response of T lymphocytes, measured as MTT absorbance, from 0.24 ± 0.02 nm to 0.16 ± 0.02 nm. Interestingly, while the activation of fibroblasts is mediated by a soluble factor, a cognate interaction ICAM-1 mediated was demonstrated to be responsible for the modulation of LFA-1, CD28 and CD69. Conclusion: Findings from this study suggest that fibroblasts play a role in the local regulation of the immune response, being able to modulate effector functions of cells recruited into sites of inflammation. [ABSTRACT FROM AUTHOR]

Allergic rhinitis is often associated with bronchial hyperresponsiveness (BHR) and airway inflammation, and it seems to be an important risk factor for the development of asthma. Specific immunotherapy (SIT) reduces symptoms and medication requirements in subjects with allergic rhinitis, but the mechanisms by which SIT promotes these beneficial effects are less clear. We have investigated the effects of Parietaria-SIT on rhinitis symptoms, BHR to inhaled methacholine, eosinophilic inflammation and cytokine production (interferon gamma and interleukin-4) in the sputum. The effect on asthma progression was also examined. Thirty non-asthmatic subjects with seasonal rhinitis and monosensitized to Parietaria judaica participated in a randomized, double-blind, placebo-controlled, parallel group study. Participants were randomly assigned to receive injections of a Parietaria pollen vaccine (n = 15) or matched placebo injections (n = 15) in a rapid updosing cluster regimen for 7 weeks, followed by monthly injections for 34 months. Throughout the 3-year study we collected data on symptoms and medication score, airway responsiveness to methacholine, eosinophilia and soluble cytokines in sputum, followed by a complete evaluation of the clinical course of atopy. Hay fever symptom and medication scores were well controlled by SIT. By the end of the study, in the placebo group, symptom and medication scores significantly increased by a median (interquartile range) of 121% (15-280%) and 263% (0-4400%) respectively (p < 0.01), whereas no significant difference was observed in the SIT group. We found no significant changes in the sputum parameters and methacholine PC15 values in both groups throughout the study. By the end of the investigation, a total of 9 out of 29 participants developed asthma symptoms; of these, seven (47%) belonged to the placebo group, whereas only 2 (14%) to the SIT-treated group (p = 0.056). In conclusion, Parietaria-SIT is effective in controlling hay fever symptoms and rescue medications, but no changes in the BHR to methacholine or sputum eosinophilia were observed. Moreover, Parietaria-SIT appears to prevent the natural progression of allergic rhinitis to asthma, suggesting that SIT should be considered earlier in the management of this condition.