Fluoxetine reduces murine graft-versus-host disease by induction of T cell immunosuppression

Serotonin reuptake inhibitors (SRIs) are widely used drugs in the treatment of depression and anxiety disorders. Although SRIs are generally regarded as safe drugs with relatively few side effects, literature suggests that high concentrations of SRIs may alter immune function. We investigated whether high-dose treatment with fluoxetine was able to suppress acute graft-versus-host disease (GvHD) in a MHC-matched, minor histocompatibility antigen mismatched murine bone marrow transplantation model. We found that high doses fluoxetine induce a significant reduction of clinical symptoms and increase survival of these animals. The amelioration of clinical GvHD was accompanied by a reduced expansion of alloreactive T cells. We further analyzed the direct in vitro effect of six SRIs on the viability and proliferation of human T cells and found an anti-proliferative and pro-apoptotic effect that was significantly larger in activated than in resting T cells. We discuss these results in the light of potential future exploration of SRIs as a novel class of T cell immunosuppressive drugs

The Dark Side of EGFP: Defective Polyubiquitination

Enhanced Green Fluorescent Protein (EGFP) is the most commonly used live cell reporter despite a number of conflicting reports that it can affect cell physiology. Thus far, the precise mechanism of GFP-associated defects remained unclear. Here we demonstrate that EGFP and EGFP fusion proteins inhibit polyubiquitination, a posttranslational modification that controls a wide variety of cellular processes, like activation of kinase signalling or protein degradation by the proteasome. As a consequence, the NF-κB and JNK signalling pathways are less responsive to activation, and the stability of the p53 tumour suppressor is enhanced in cell lines and in vivo. In view of the emerging role of polyubiquitination in the regulation of numerous cellular processes, the use of EGFP as a live cell reporter should be carefully considered

Aryl hydrocarbon receptor (AhR) agonists suppress interleukin-6 expression by bone marrow stromal cells: an immunotoxicology study

BACKGROUND: Bone marrow stromal cells produce cytokines required for the normal growth and development of all eight hematopoietic cell lineages. Aberrant cytokine production by stromal cells contributes to blood cell dyscrasias. Consequently, factors that alter stromal cell cytokine production may significantly compromise the development of normal blood cells. We have shown that environmental chemicals, such as aromatic hydrocarbon receptor (AhR) agonists, suppress B lymphopoiesis by modulating bone marrow stromal cell function. Here, we extend these studies to evaluate the potential for two prototypic AhR agonists, 7,12-dimethylbenz [a]anthracene (DMBA) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), to alter stromal cell cytokine responses. METHODS: Bone marrow stromal cells were treated with AhR agonists and bacterial lipopolysaccharide (LPS) to mimic innate inflammatory cytokine responses and to study the effects of AhR ligands on those responses. Steady state cytokine RNA levels were screened by RNAse protection assays (RPA) and quantified by real-time PCR. Cytokine (IL-6) protein production was measured by ELISA. NF-κB EMSAs were used to study IL-6 transcriptional regulation. RESULTS: RPAs indicated that AhR(+ )bone marrow stromal cells consistently up-regulated genes encoding IL-6 and LIF in response to LPS, presumably through activation of Toll-like receptor 4. Pre-treatment with low doses of DMBA or TCDD selectively abrogated IL-6 gene induction but had no effect on LIF mRNA. Real-time-PCR indicated a significant inhibition of IL-6 mRNA by AhR ligands within 1 hour of LPS challenge which was reflected in a profound down-regulation of IL-6 protein induction, with DMBA and TCDD suppressing IL-6 levels as much as 65% and 88%, respectively. This potent inhibitory effect persisted for at least 72 hours. EMSAs measuring NF-κB binding to IL-6 promoter sequences, an event known to induce IL-6 transcription, indicated a significant decrease in the LPS-mediated induction of DNA-binding RelA/p50 and c-Rel/p50 heterodimers in the presence of DMBA. CONCLUSIONS: Common environmental AhR agonists can suppress the response to bacterial lipopolysaccharide, a model for innate inflammatory responses, through down-regulation of IL-6, a cytokine critical to the growth of several hematopoietic cell subsets, including early B cells. This suppression occurs at least at the level of IL-6 gene transcription and may be regulated by NF-κB

Temporomandibular joint arthritis in juvenile idiopathic arthritis: Prevalence, clinical and radiological signs, and relation to dentofacial morphology

OBJECTIVE: To perform a prospective, comprehensive, clinical, and radiological evaluation of temporomandibular joint (TMJ) involvement and its influence on craniofacial growth, in a cohort of patients with juvenile idiopathic arthritis (JIA), representing all JIA subtypes. METHODS: Clinical rheumatologic and orthodontic evaluations were performed in 100 patients with JIA [12 systemic arthritis, 24 rheumatoid factor (RF)-negative polyarthritis, 1 RF-positive polyarthritis, 39 oligoarthritis, 22 enthesitis-related arthritis, 2 psoriatic arthritis]. An orthopantomogram and lateral cephalogram were performed in 46 patients. The prevalence of TMJ arthritis was studied in relation to JIA subtype and disease characteristics; cephalometric measurements were compared to those from age- and sex-matched healthy controls. RESULTS: Whereas 55% of patients with JIA had at least one symptom/sign of TMJ arthritis, 78% of the radiographed group exhibited condylar lesions. The presence of condylar damage was not related to clinical orthodontic findings or to JIA subtype, disease activity, severity, or duration. Patients with JIA exhibited larger mandibular plane and A-nasion-B angles, larger total anterior facial height, smaller interincisal and sella-nasion-B angles, and shorter mandibular ramus lengths than their age- and sex-matched controls. Craniofacial alterations were clearly related to the presence of condylar damage, even when present at a minimal degree. CONCLUSION: Our data show that TMJ condylar damage occurs very frequently in JIA, and irrespective of JIA subtype; condylar lesions can present early, progress insidiously, and -- even at a minimal degree -- can severely alter the craniofacial profile. We propose that the followup of patients with JIA should include early and regular evaluation by an orthodontist, supplemented with radiographic TMJ imaging.status: publishe

Solid Tumor-Induced Immune Regulation Alters the GvHD/GvT Paradigm after Allogenic Bone Marrow Transplantation

Growth of solid tumors is often associated with the development of an immunosuppressive tumor microenvironment (TME). It has been suggested that the influence of the TME may extend beyond the local tumor and results in systemic immunosuppression. Here, we utilize two murine cancer models to explore the influence of solid tumors on the occurrence of alloreactivity-driven GvHD and graft-versus-solid tumor (GvT) effects following MHC-mismatched allogeneic bone marrow transplantation (allo-BMT). Melanoma- or colon carcinoma-bearing C57BL/6 mice did not develop GvHD after BMT even when the bone marrow inoculum was supplemented with donor-type splenocytes. This protection against GvHD required the presence of tumors because its resection prior to allo-BMT promptly resulted in development of GvHD. In addition, tumor-bearing mice given T-cell-depleted allo-BMT (allo-TCD-BMT) failed to develop GvHD and also showed significantly stronger GvT effects than mice given allo-BMT. The GvT effects in allo-TCD-BMT recipients were associated with profound changes in tumor-infiltrating cells compared with that in allo-BMT recipients, with significantly reduced donor-derived regulatory T cells (Treg), increased cytotoxic effector (IFNγhi) CD8 T cells, and increased M1 macrophages (iNOShi, arginaselo, and IL10lo); the use of macrophage-depleted bone marrow abrogated the GvT effects. Collectively, these results indicate that the presence of M1 macrophages may disrupt the generation of donor-type Treg cells so that the immunomodulatory effect of the TME can affect systemic immunity. SIGNIFICANCE: These findings show that cells such as T cells or macrophages in the bone marrow inoculum may interfere with the systemic and local immune reactivity against tumors.status: publishe