Gene network analysis of bone marrow mononuclear cells reveals activation of multiple kinase pathways in human systemic lupus erythematosus.

BACKGROUND: Gene profiling studies provide important information for key molecules relevant to a disease but are less informative of protein-protein interactions, post-translational modifications and regulation by targeted subcellular localization. Integration of genomic data and construction of functional gene networks may provide additional insights into complex diseases such as systemic lupus erythematosus (SLE). METHODOLOGY/PRINCIPAL FINDINGS: We analyzed gene expression microarray data of bone marrow mononuclear cells (BMMCs) from 20 SLE patients (11 with active disease) and 10 controls. Gene networks were constructed using the bioinformatic tool Ingenuity Gene Network Analysis. In SLE patients, comparative analysis of BMMCs genes revealed a network with 19 central nodes as major gene regulators including ERK, JNK, and p38 MAP kinases, insulin, Ca(2+) and STAT3. Comparison between active versus inactive SLE identified 30 central nodes associated with immune response, protein synthesis, and post-transcriptional modification. A high degree of identity between networks in active SLE and non-Hodgkin's lymphoma (NHL) patients was found, with overlapping central nodes including kinases (MAPK, ERK, JNK, PKC), transcription factors (NF-kappaB, STAT3), and insulin. In validation studies, western blot analysis in splenic B cells from 5-month-old NZB/NZW F1 lupus mice showed activation of STAT3, ITGB2, HSPB1, ERK, JNK, p38, and p32 kinases, and downregulation of FOXO3 and VDR compared to normal C57Bl/6 mice. CONCLUSIONS/SIGNIFICANCE: Gene network analysis of lupus BMMCs identified central gene regulators implicated in disease pathogenesis which could represent targets of novel therapies in human SLE. The high similarity between active SLE and NHL networks provides a molecular basis for the reported association of the former with lymphoid malignancies.

The programmed death 1/programmed death ligand 1 inhibitory pathway is up-regulated in rheumatoid synovium and regulates peripheral T cell responses in human and murine arthritis.

OBJECTIVE: T cells play a major role in the pathogenesis of rheumatoid arthritis (RA). The programmed death 1 (PD-1)/programmed death ligand 1 (PDL-1) pathway is involved in peripheral tolerance through inhibition of T cells at the level of synovial tissue. The aim of this study was to examine the role of PD-1/PDL-1 in the regulation of human and murine RA. METHODS: In synovial tissue and synovial fluid (SF) mononuclear cells from patients with RA, expression of PD-1/PDL-1 was examined by immunohistochemistry and flow cytometry, while PD-1 function was assessed in RA peripheral blood (PB) T cells after stimulation of the cells with anti-CD3 and PDL-1.Fc to crosslink PD-1. Collagen-induced arthritis (CIA) was induced in PD-1(-/-) C57BL/6 mice, and recombinant PDL-1.Fc was injected intraperitoneally to activate PD-1 in vivo. RESULTS: RA synovium and RA SF were enriched with PD-1+ T cells (mean +/- SEM 24 +/- 5% versus 4 +/- 1% in osteoarthritis samples; P = 0.003) and enriched with PDL-1+ monocyte/macrophages. PD-1 crosslinking inhibited both T cell proliferation and production of interferon-gamma (IFNgamma) in RA patients; PB T cells incubated with RA SF, as well as SF T cells from patients with active RA, exhibited reduced PD-1-mediated inhibition of T cell proliferation at suboptimal, but not optimal, concentrations of PDL-1.Fc. PD-1(-/-) mice demonstrated increased incidence of CIA (73% versus 36% in wild-type mice; P < 0.05) and greater severity of CIA (mean maximum arthritis score 5.0 versus 2.3 in wild-type mice; P = 0.040), and this was associated with enhanced T cell proliferation and increased production of cytokines (IFNgamma and interleukin-17) in response to type II collagen. PDL-1.Fc treatment ameliorated the severity of CIA and reduced T cell responses. CONCLUSION: The negative costimulatory PD-1/PDL-1 pathway regulates peripheral T cell responses in both human and murine RA. PD-1/PDL-1 in rheumatoid synovium may represent an additional target for immunomodulatory therapy in RA.

Evaluation of potential retinal toxicity of adalimumab (Humira).

PURPOSE: The purpose of this study is to evaluate the retinal toxicity of two doses of adalimumab (Humira), a recombinant human IgG1 monoclonal antibody specific for human tumor necrosis factor (TNF), when injected intravitreally in rabbits. METHODS: Sixteen male pigmented rabbits (divided into two groups, eight animals per group) were used for this study. Two concentrations of adalimumab were tested: 0.5 mg/0.1 ml and 5 mg/0.1 ml. Each concentration was injected intravitreally randomly in one eye (study group) of each rabbit (group I received 0.5 mg/0.1 ml and group II received 5.0 mg/0.1 ml), while in the other eye (control group) 0.1 ml of sterile balanced saline solution (BSS) was injected. Slit-lamp and funduscopic examinations were performed every second day for 2 weeks for signs of infection, inflammation and toxicity. A baseline electroretinogram (ERG) was performed before the experiment and at the last follow-up day (day 14). ERG examination followed ISCEV standards. At the last follow-up day, the animals were sacrificed and the enucleated eyes were prepared for histological evaluation of retinal toxicity. RESULTS: No differences in ERG responses at photopic and scotopic conditions were observed in eyes injected with either concentration of adalimumab or BSS. Furthermore, histologic examination of the retina in the enucleated eyes (in all groups) did not demonstrate any evidence of drug toxicity. CONCLUSIONS: Intravitreal adalimumab did not appear toxic to the retina in this experimental model at concentrations of 0.5 and 5 mg. If found safe in additional studies, intravitreally injected adalimumab could be evaluated for efficacy in the treatment of inflammatory eye conditions.

Gene expression in systemic lupus erythematosus: bone marrow analysis differentiates active from inactive disease and reveals apoptosis and granulopoiesis signatures.

OBJECTIVE: The cells of the immune system originate from the bone marrow, where many of them also mature. This study was undertaken to examine gene expression in the bone marrow of patients with systemic lupus erythematosus (SLE), in order to better understand the aberrant immune response in this disease. METHODS: Bone marrow mononuclear cells (BMMCs) from 20 SLE patients (11 with active disease and 9 with inactive disease) and peripheral blood mononuclear cells (PBMCs) from 27 patients (16 with active disease and 11 with inactive disease) were studied; BMMCs and PBMCs from 7 healthy individuals and 3 osteoarthritis patients were studied as controls. Samples were analyzed on genome-scale DNA microarrays, with 21,329 genes represented. RESULTS: We identified 102 genes involved in various biologic processes that were differentially expressed between patient and control BMMCs; 53 of them are genes that are involved in major networks, including cell death, growth, signaling, and proliferation. Comparative analysis revealed 88 genes that were differentially expressed between bone marrow and blood, the majority of which are involved in cell growth and differentiation, cellular movement and morphology, immune response, and other hematopoietic cell functions. Unsupervised clustering of highly expressed genes revealed 2 major SLE patient clusters (active disease and inactive disease) based on gene expression in bone marrow, but not in peripheral blood. The up-regulated genes in the bone marrow of patients with active disease included genes involved in cell death and granulopoiesis. CONCLUSION: Microarray analysis of the bone marrow differentiated active from inactive SLE and provided further evidence of the role of apoptosis and granulocytes in the pathogenesis of the disease.