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

Genetics of immunoglobulin-A vasculitis (Henoch-Schönlein purpura): An updated review

Immunoglobulin-A vasculitis (IgAV) is classically a childhood small-sized blood vessel vasculitis with predominant involvement of the skin. Gastrointestinal and joint manifestations are common in patients diagnosed with this condition. Nephritis, which is more severe in adults, constitutes the most feared complication of this vasculitis. The molecular bases underlying the origin of IgAV have not been completely elucidated. Nevertheless, several pieces of evidence support the claim that genes play a crucial role in the pathogenesis of this disease. The human leukocyte antigen (HLA) region is, until now, the main genetic factor associated with IgAV pathogenesis. Besides a strong association with HLA class II alleles, specifically HLA-DRB1 alleles, HLA class I alleles also seem to influence on the predisposition of this disease. Other gene polymorphisms located outside the HLA region, including those coding cytokines, chemokines, adhesion molecules as well as those related to T-cells, aberrant glycosylation of IgA1, nitric oxide production, neoangiogenesis, renin-angiotensin system and lipid, Pyrin and homocysteine metabolism, may be implicated not only in the predisposition to IgAV but also in its severity. An update of the current knowledge of the genetic component associated with the pathogenesis of IgAV is detailed in this review.Acknowledgements: RL-Mis supported by the Miguel Servet I programme of the Spanish Ministry of Economy and Competitiveness through the grant CP16/ 00033. FG is recipient of a Sara Borrell postdoctoral fellowship from the “Instituto Carlos III de Salud” at the Spanish Ministry of Health (Spain) (CD15/00095). SR-M is supported by funds from the RETICS Program (RIER) (RD16/0012/0009). FDC is supported by the Ramón y Cajal programme of the Spanish Ministry of Economy and Competitiveness through the grant RYC-2014-16458

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

Crucial role of timing of donor lymphocyte infusion in generating dissociated graft-versus-host and graft-versus-leukemia responses in mice receiving allogeneic bone marrow transplants

A murine model of minor histocompatibility antigen-mismatched bone marrow transplantation (BMT) was used to study the role of timing of donor lymphocyte infusion (DLI) in eliciting graft-versus-host (GVH) and graft-versus-leukemia (GVL) reactivity. We gave DLI at weeks 3 and 12 after BMT and related its ability to induce a GVL effect with (1) evolution of T cell chimeric status and (2) the extent to which DLI could elicit lymphohematopoietic GVH (LHGVH) reactivity. All mice remained free of GVH disease, but only week 3 DLI chimeras exhibited a significant GVL response when challenged with host-type leukemia cells. In these week 3 DLI chimeras, host-reactive T cells were found to proliferate in vivo (5- [and-6]-carboxyfluorescein diacetate, succinimidyl esther [CFSE]-labeled DLI inocula, TCR-Vbeta6(+) T-cell frequency) and T-cell chimerism rapidly converted from mixed into complete donor type, indicating the occurrence of LHGVH reactivity. In week 12 chimeras, DLI elicited none of the activities noted at week 3. Yet, in both instances, splenocytes, recovered following DLI, generated an equally strong antihost proliferative response in a mixed lymphocyte reaction, thereby arguing against a decisive role of regulatory cells. The lack of in vivo LHGVH reactivity after week 12 DLI was associated with a substantially increased level of pre-existing host-type T-cell chimerism. We conclude that elicitation of a GVL effect may require LHGVH reactivity and that the reason why timing of DLI was critical for obtaining LHGVH reactivity and the desired GVL effect may lie in the evolution of chimeric status. A possible direct involvement of residual host-type antigen-presenting cells in eliciting LHGVH reactivity after DLI should be studied using models that allow chimerism analysis in non-T-cell lineages.status: publishe

Transient expansion of Mac1+Ly6-G+Ly6-C+ early myeloid cells with suppressor activity in spleens of murine radiation marrow chimeras: possible implications for the graft-versus-host and graft-versus-leukemia reactivity of donor lymphocyte infusions

A murine model of minor histocompatibility antigen (miHCag)-mismatched bone marrow transplantation (BMT) was used to study the development of immunoregulatory cells in the posttransplantation period and their possible involvement in the dissociated graft-versus-host (GVH) and graft-versus-leukemia (GVL) reactivity of posttransplantation donor lymphocyte infusions (DLIs). DLI, applied immediately after BMT, induced GVH disease (GVHD), but when DLI was delayed for 3 weeks, GVHD was avoided while a distinct GVL response was allowed to develop. A population of Mac1+Ly6-G+Ly6-C+ immature myeloid cells, found in small numbers in normal mice, strongly expanded in spleens of chimeras, reaching a maximum level at week 3 and returning to base level by week 12. Upon isolation, these cells exhibited interferon-gamma (IFN-gamma)-dependent, nitric oxide (NO)-mediated suppressor activity toward in vitro alloresponses, suggesting that, after in vivo DLI, they are activated by IFN-gamma to produce NO and suppress GVH reactivity. Because not only alloactivated T-cell proliferation but also leukemia cell growth was found susceptible to inhibition by exogenous NO, in vivo activation of these cells after DLI may explain the occurrence of a GVL effect despite suppression of GVHD. This suggested sequence of events was supported by the finding that the ex vivo antihost proliferative response of spleen cells, recovered shortly after in vivo DLI, was characterized by strong mRNA production of the monokines interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha (TNF-alpha) and of inducible nitric oxide synthase (iNOS). Our data suggest that transiently expanding Mac1+Ly6-G+Ly6-C+ immature myeloid cells (probably as a result of extramedullary myelopoiesis) may play a role in controlling GVH while promoting GVL reactivity of DLI after allogeneic BMT.status: publishe

Absence of Xeno-rejection and Xenoantibody Production in IL-7 KO Recipients After Xenoheart, but not after Xenoskin Transplantation

status: publishe