Myeloid differentiation primary response protein 88 blockade upregulates indoleamine 2,3-dioxygenase expression in rheumatoid synovial fibroblasts

Indoleamine 2,3-dioxygenase (IDO) is a key negative regulator of immune responses and has been implicated in tumor tolerance, autoimmune disease and asthma. IDO was detected in the joint synovial tissue in the inflammatory microenvironment of rheumatoid arthritis (RA), but IDO expression in joint synovial tissue is not sufficient to overcome the inflamed synovial environment. This study aimed to unravel the mechanisms involving the failure to activate tolerogenic IDO in the inflamed joint. We demonstrate that both poly (I:C) and lipopolysaccharide (LPS) induce expression of IDO in synovial fibroblasts. However, inflammatory cytokines such as IL-17, TNF-alpha, IL-12, IL-23 and IL-16 did not induce IDO expression. Poly (I:C) appeared to induce higher IDO expression than did LPS. Surprisingly, toll-like receptor (TLR)4-mediated IDO expression was upregulated after depletion of myeloid differentiation primary response protein 88 (MyD88) in synovial fibroblasts using small interfering RNA (siRNA). IDO, TLR3 and TLR4 were highly expressed in synovial tissue of RA patients compared with that of osteoarthritis patients. In addition, RA patients with severe disease activity had higher levels of expression of IDO, TLR3 and TLR4 in the synovium than patients with mild disease activity. These data suggest that upregulation of IDO expression in synovial fibroblasts involves TLR3 and TLR4 activation by microbial constituents. We showed that the mechanisms responsible for IDO regulation primarily involve MyD88 signaling in synovial fibroblasts, as demonstrated by siRNA-mediated knockdown of MyD88.

Modulation of the Surface Expression of CD158 Killer Cell Ig-like Receptor by Interleukin-2 and Transforming Growth Factor-beta

Killer cell Ig-like receptor (KIR) binds to HLA class I molecules on the surface of target cells, and it confers inhibitory signals to NK cells. Although NK cytotoxicity can be affected by the change of the surface expression of KIR on NK cells, the effect of cytokines on the regulation of KIR expression has not been thoroughly investigated. Here in our study, we investigated the effect of several cytokines, including IL-2, TGF-beta, IFN-gamma, IL-12 and IL-18, on the surface expression of CD158 KIR, which binds to HLA-C, by the use of FACS analysis. In the isolated NK cells, IL-2 obviously increased the surface expression of CD158 KIR after 72 hr in vitro culture, and this was evidenced by the increased percentage of CD158+ NK cells and the increased mean fluorescence intensity of CD158 in CD158+ NK cells. In contrast, TGF-beta decreased the surface expression of CD158 KIR after 72 hr culture. However, IFN-gamma, IL-12 and IL-18 did not change the expression of CD158 KIR. The modulated expression of KIR by IL-2 and TGF-beta can be associated with the changed NK-cytotoxic target-discriminating ability of NK cells upon their exposure to IL-2 and TGF-beta.

Citoquinas: la internet biológica ¿futura terapia en el asma bronquial? / Cytokines: the biological internet, the future therapy of bronchial asthma?

Las citoquinas son polipéptidos producidos por variadas células nucleadas que actúan como intercomunicadores celulares. Participan en funciones de defensa y reparación del adño del organismo y restablecimiento de la homeostasis. En los últimos años y gracias al desarrollo de la biología molecular, ha sido posible identificar y producir en el laboratorio numerosas citoquinas disponibles en el tratamiento de diversas enfermedades. En el asma bronquial existe un desbalance de algunas citoquinas con predominio de la producción de las interleuquinas (ILs) dependientes de los linfocitos tipo Th-2, como IL-4 e IL-5, las cuales inducen la producción de IgE y la eosinofilia, respectivamente. Actualmente están en marcha estudios clínicos tendientes a bloquear o impedir la acción de la IL-4 e IL-5 mediante anticuerpos monoclonales anti-IL o mediante la acción inhibidora sobre estas citoquinas que ejerce la IL-12. En esta revisión bibliográfica se analiza el estado actual de esta nueva futura terapia del asma