Differential Accumulation and Activation of Monocyte and Dendritic Cell Subsets in Inflamed Synovial Fluid Discriminates Between Juvenile Idiopathic Arthritis and Septic Arthritis.

Despite their distinct etiology, several lines of evidence suggest that innate immunity plays a pivotal role in both juvenile idiopathic arthritis (JIA) and septic arthritis (SA) pathophysiology. Indeed, monocytes and dendritic cells (DC) are involved in the first line of defense against pathogens and play a critical role in initiating and orchestrating the immune response. The aim of this study was to compare the number and phenotype of monocytes and DCs in peripheral blood (PB) and synovial fluid (SF) from patients with JIA and SA to identify specific cell subsets and activation markers associated with pathophysiological mechanisms and that could be used as biomarkers to discriminate both diseases. The proportion of intermediate and non-classical monocytes in the SF and PB, respectively, were significantly higher in JIA than in SA patients. In contrast the proportion of classical monocytes and their absolute numbers were higher in the SF from SA compared with JIA patients. Higher expression of CD64 on non-classical monocyte was observed in PB from SA compared with JIA patients. In SF, higher expression of CD64 on classical and intermediate monocyte as well as higher CD163 expression on intermediate monocytes was observed in SA compared with JIA patients. Moreover, whereas the number of conventional (cDC), plasmacytoid (pDC) and inflammatory (infDC) DCs was comparable between groups in PB, the number of CD141+ cDCs and CD123+ pDCs in the SF was significantly higher in JIA than in SA patients. CD14+ infDCs represented the major DC subset in the SF of both groups with potent activation assessed by high expression of HLA-DR and CD86 and significant up-regulation of HLA-DR expression in SA compared with JIA patients. Finally, higher activation of SF DC subsets was monitored in SA compared with JIA with significant up-regulation of CD86 and PDL2 expression on several DC subsets. Our results show the differential accumulation and activation of innate immune cells between septic and inflammatory arthritis. They strongly indicate that the relative high numbers of CD141+ cDC and CD123+ pDCs in SF are specific for JIA while the over-activation of DC and monocyte subsets is specific for SA.

Arthritis sensory and motor scale: predicting functional deficits from the clinical score in collagen-induced arthritis.

BACKGROUND: In the collagen-induced arthritis (CIA) mouse model, inflammation readouts are usually quantified using operator-dependent clinical scoring systems, and no systematic relationship with functional deficits has been detected. In this study, we extensively quantified sensory and motor deficits in CIA mice during natural disease progression and therapeutic treatment. Then, we used these data to build a scale to predict functional deficits on the basis of the classical clinical score. METHODS: Using the CIA mouse model, we longitudinally screened multiple approaches to assess locomotion (open field test, Catwalk™), sensitivity (Von Frey, Hargreaves, static weight-bearing tests), and inflammation (skin temperature), and identified the most accurate tests to correlate sensory and motor deficits with disease severity, measured by clinical score. We then used these tests to characterize functional deficits in control (naïve and mice injected with complete Freund's adjuvant) and CIA mice, either untreated or treated with methotrexate to prevent functional deficits. By mathematical approaches, we finally investigated the relationship between functional deficits and clinical score. RESULTS: We found that the functional disability scores obtained with the open field, Catwalk™, Hargreaves, and skin temperature tests significantly correlated with the clinical score in CIA mice, either untreated or treated with methotrexate. Mathematical correlation showed that motor deficits, robustly characterized by two different tests, were twice more responsive than thermal sensitivity deficits. CONCLUSION: We propose the arthritis sensory and motor (ArthriSM) scale as a new theranostic tool to predict motor and sensory deficit based on the clinical score, in the experimental mouse model of CIA. This ArthriSM scale may facilitate the transfer of knowledge between preclinical and clinical studies.

Polyoxidonium® Activates Cytotoxic Lymphocyte Responses Through Dendritic Cell Maturation: Clinical Effects in Breast Cancer.

Immunotherapy, which is seen as a major tool for cancer treatment, requires, in some cases, the presence of several agents to maximize its effects. Adjuvants can enhance the effect of other agents. However, despite their long-time use, only a few adjuvants are licensed today, and their use in cancer treatment is rare. Azoximer bromide, marketed under the trade name Polyoxidonium® (PO), is a copolymer of N-oxidized 1,4-ethylenepiperazine and (N-carboxyethyl)-1,4-ethylene piperazinium bromide. It has been described as an immune adjuvant and immunomodulator that is clinically used with excellent tolerance. PO is used in the treatment and prophylaxis of diseases connected with damage to the immune system, and there is interest in testing it in antitumor therapy. We show here that PO treatment for 1 week induced positive pathological changes in 6 out of 20 patients with breast cancer, including complete response in a triple-negative patient. This correlated with an increased tumor CD4+ T-lymphocyte infiltration. The immune effects of PO are associated with myeloid cell activation, and little is known about the action of PO on lymphocyte lineages, such as natural killer (NK) and T cells. We reveal that PO increases T-cell proliferation in vitro without negative effects on any activation marker. PO does not affect dendritic cell (DC) viability and increases the expansion of immature DC (iDC) and mature DC (mDC) at 100 µg/ml, and it stimulates expression of several DC co-stimulatory molecules, inducing the proliferation of allogeneic T cells. In contrast, PO decreases DC viability when added at day 5 post-expansion. PO is not toxic for NK cells at doses up to 100 µM and does not affect their activation, maturation, and cytotoxicity but tends to increase degranulation. This could be beneficial against target cells that show low sensitivity to NK cells, e.g., solid tumor cells. Finally, we have found great variability in PO response between donors. In summary, our in vitro results show that PO increases the number of costimulatory molecules on DC that prime T cells, favoring the production of effector T cells. This may support the future clinical development of PO in cancer treatment.

Synovial-Fluid miRNA Signature for Diagnosis of Juvenile Idiopathic Arthritis.

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory rheumatism in childhood; microRNAs (miRNAs) have been proposed as diagnostic biomarkers. Although joints are the primary targets for JIA, a synovial fluid-based miRNA signature has never been studied. We aim to identify miRNA biomarkers in JIA by comparing synovial fluid and serum samples from children with JIA and K.kingae septic arthritis (SA). With next-generation high-throughput sequencing, we measured the absolute levels of 2083 miRNAs in synovial fluid and serum from an exploratory cohort of children and validated differentially expressed miRNAs in a replication study by using RT-qPCR. We identified a 19-miRNA signature only in synovial fluid samples that was significantly deregulated, with at least 2-fold change in expression, in JIA versus SA (p < 0.01). The combination of miR-6764-5p, miR-155, and miR-146a-5p expression in synovial fluid yielded an area under the receiver operating characteristic curve of 1 (95% CI 0.978 to 1), thereby perfectly differentiating JIA from SA in children. We propose, for the first time, a synovial fluid-specific miRNA signature for JIA and associated signaling pathways that may indicate potential biomarkers to assist in the classification and differential diagnosis of JIA and help in understanding JIA pathogenesis.

Injection of Adipose-Derived Stromal Cells in the Knee of Patients with Severe Osteoarthritis has a Systemic Effect and Promotes an Anti-Inflammatory Phenotype of Circulating Immune Cells.

Rationale: Recent studies confirmed that osteoarthritis (OA) is associated with systemic inflammation. Adipose-derived stromal cells (ASCs) could become the most promising cell-based therapy in OA, based not only on their differentiation capacities and trophic and paracrine effects on the existing cartilage, but also on their immunomodulatory properties. Here, we wanted to determine the biological effect of autologous ASC intra-articular (IA) injection. Method: To this aim, we monitored the profile of immune cells in fresh peripheral blood after IA injection of autologous ASCs in the knee of 18 patients with severe OA (ADIPOA phase I study). Specifically, we used 8-color flow cytometry antibody panels to characterize the frequencies of innate and adaptive immune cell subsets (monocytes, dendritic cells, regulatory T cells and B cells) in blood samples at baseline (before injection) and one week, one month and three months after ASC injection. Results: We found that the percentage of CD4+CD25highCD127lowFOXP3+ regulatory T cells was significantly increased at 1 month after ASC injection, and this effect persisted for at least 3 months. Moreover, CD24highCD38high transitional B cells also were increased, whereas the percentage of classical CD14+ monocytes was decreased, at 3 months after ASC injection. These results suggest a global switch toward regulatory immune cells following IA injection of ASCs, underscoring the safety of ASC-based therapy. We did not find any correlation between the scores for the Visual Analogic Scale for pain, the Western Ontario and McMaster Universities Osteoarthritis Index (pain subscale and total score) at baseline and the immune cell profile changes, but this could be due to the small number of analyzed patients. Conclusion: ASCs may drive an immediate local response by releasing paracrine factors and cytokines, and our results suggest that ASCs could also initiate a cascade resulting in a long-lasting systemic immune modulation.

Delivery of miR-146a to Ly6Chigh Monocytes Inhibits Pathogenic Bone Erosion in Inflammatory Arthritis.

Rationale: Monocytes play critical roles in the pathogenesis of arthritis by contributing to the inflammatory response and bone erosion. Among genes involved in regulating monocyte functions, miR-146a negatively regulates the inflammatory response and osteoclast differentiation of monocytes. It is also the only miRNA reported to differentially regulate the cytokine response of the two classical Ly6Chigh and non-classical Ly6Clow monocyte subsets upon bacterial challenge. Although miR-146a is overexpressed in many tissues of arthritic patients, its specific role in monocyte subsets under arthritic conditions remains to be explored. Methods: We analyzed the monocyte subsets during collagen-induced arthritis (CIA) development by flow cytometry. We quantified the expression of miR-146a in classical and non-classical monocytes sorted from healthy and CIA mice, as well as patients with rheumatoid arthritis (RA). We monitored arthritis features in miR-146a-/- mice and assessed in vivo the therapeutic potential of miR-146a mimics delivery to Ly6Chigh monocytes. We performed transcriptomic and pathway enrichment analyses on both monocyte subsets sorted from wild type and miR-146a-/- mice. Results: We showed that the expression of miR-146a is reduced in the Ly6Chigh subset of CIA mice and in the analogous monocyte subset (CD14+CD16-) in humans with RA as compared with healthy controls. The ablation of miR-146a in mice worsened arthritis severity, increased osteoclast differentiation in vitro and bone erosion in vivo. In vivo delivery of miR-146a to Ly6Chigh monocytes, and not to Ly6Clow monocytes, rescues bone erosion in miR-146a-/- arthritic mice and reduces osteoclast differentiation and pathogenic bone erosion in CIA joints of miR-146a+/+ mice, with no effect on inflammation. Silencing of the non-canonical NF-κB family member RelB in miR-146a-/- Ly6Chigh monocytes uncovers a role for miR-146a as a key regulator of the differentiation of Ly6Chigh, and not Ly6Clow, monocytes into osteoclasts under arthritic conditions. Conclusion: Our results show that classical monocytes play a critical role in arthritis bone erosion. They demonstrate the theranostics potential of manipulating miR-146a expression in Ly6Chigh monocytes to prevent joint destruction while sparing inflammation in arthritis.

Characterization of human FCRL4-positive B cells.

FCRL4 is an immunoregulatory receptor that belongs to the Fc receptor-like (FCRL) family. In healthy individuals, FCRL4 is specifically expressed by memory B cells (MBCs) localized in sub-epithelial regions of lymphoid tissues. Expansion of FCRL4+ B cells has been observed in blood and other tissues in various infectious and autoimmune disorders. Currently, the mechanisms involved in pathological FCRL4+ B cell generation are actively studied, but they remain elusive. As in vivo FCRL4+ cells are difficult to access and to isolate, here we developed a culture system to generate in vitro FCRL4+ B cells from purified MBCs upon stimulation with soluble CD40 ligand and/or CpG DNA to mimic T-cell dependent and/or T-cell independent activation, respectively. After 4 days of stimulation, FCRL4+ B cells represented 17% of all generated cells. Transcriptomic and phenotypic analyses of in vitro generated FCRL4+ cells demonstrated that they were closely related to FCRL4+ tonsillar MBCs. They strongly expressed inhibitory receptor genes, as observed in exhausted FCRL4+ MBCs from blood samples of HIV-infected individuals with high viremia. In agreement, cell cycle genes were significantly downregulated and the number of cell divisions was two-fold lower in in vitro generated FCRL4+ than FCRL4- cells. Finally, due to their reduced proliferation and differentiation potential, FCRL4+ cells were less prone to differentiate into plasma cells, differently from FCRL4- cells. Our in vitro model could be of major interest for studying the biology of normal and pathological FCRL4+ cells.

TP53 drives invasion through expression of its Δ133p53ß variant.

TP53 is conventionally thought to prevent cancer formation and progression to metastasis, while mutant TP53 has transforming activities. However, in the clinic, TP53 mutation status does not accurately predict cancer progression. Here we report, based on clinical analysis corroborated with experimental data, that the p53 isoform Δ133p53ß promotes cancer cell invasion, regardless of TP53 mutation status. Δ133p53ß increases risk of cancer recurrence and death in breast cancer patients. Furthermore Δ133p53ß is critical to define invasiveness in a panel of breast and colon cell lines, expressing WT or mutant TP53. Endogenous mutant Δ133p53ß depletion prevents invasiveness without affecting mutant full-length p53 protein expression. Mechanistically WT and mutant Δ133p53ß induces EMT. Our findings provide explanations to 2 long-lasting and important clinical conundrums: how WT TP53 can promote cancer cell invasion and reciprocally why mutant TP53 gene does not systematically induce cancer progression.

Differential effects of lenalidomide during plasma cell differentiation.

Thalidomide, lenalidomide and pomalidomide have greatly improved the outcome of patients with multiple myeloma. However, their effects on plasma cells, the healthy counterpart of myeloma cells, are unknown. Here, we investigated lenalidomide effects on normal human plasma cell generation using an in vitro model. Lenalidomide inhibited the generation of pre-plasmablasts and early plasma cells, while it moderately affected plasmablast production. It also reduced the expression level of Ikaros, Aiolos, and IRF4 transcription factors, in plasmablasts and early plasma cells. This suggests that their differential sensitivity to lenalidomide is not due to a difference in Ikaros or Aiolos degradation. Lenalidomide also inhibited long-lived plasma cell generation, but did not impair their long-term survival once generated. This last observation is in agreement with the finding that lenalidomide treatment for 3-18 months did not affect the bone marrow healthy plasma cell count in allografted patients with multiple myeloma. Our findings should prompt to investigate whether lenalidomide resistance in patients with multiple myeloma could be associated with the emergence of malignant plasmablasts or long-lived plasma cells that are less sensitive to lenalidomide.

Nonclassical CD4+CD49b+ Regulatory T Cells as a Better Alternative to Conventional CD4+CD25+ T Cells To Dampen Arthritis Severity.

Promising immunotherapeutic strategies are emerging to restore tolerance in autoimmune diseases by triggering an increase in the number and/or the function of endogenous regulatory T (Treg) cells, which actively control pathological immune responses. Evidence suggests a remarkable heterogeneity in peripheral Treg cells that warrants their better characterization in terms of phenotype and suppressive function, to determine which subset may be optimally suitable for a given clinical situation. We found that repetitive injections of immature dendritic cells expanded Foxp3-negative CD49b(+) Treg cells that displayed an effector memory phenotype. These expanded Treg cells were isolated ex vivo for transcriptome analysis and found to contain multiple transcripts of the canonical Treg signature shared mainly by CD25(+) but also by other subphenotypes. We characterized the CD49b(+) Treg cell phenotype, underscoring its similarities with the CD25(+) Treg cell phenotype and highlighting some differential expression patterns for several markers, including lymphocyte activation gene 3, KLRG1, CD103, ICOS, CTLA-4, and granzyme B. Comparison of the CD25(+) and CD49b(+) Treg cells' suppressive mechanisms, in vitro and in vivo, revealed the latter's potent suppressive activity, which was partly dependent on IL-10 secretion. Altogether, our results strongly suggest that expression of several canonical Treg cell markers and suppressive function could be Foxp3 independent, and underscore the therapeutic potential of IL-10-secreting CD49b(+) Treg cells in arthritis.

Adipose Mesenchymal Stem Cells Isolated after Manual or Water-jet-Assisted Liposuction Display Similar Properties.

Mesenchymal stem or stromal cells (MSC) are under investigation in many clinical trials for their therapeutic potential in a variety of diseases, including autoimmune and inflammatory disorders. One of the main sources of MSCs is the adipose tissue, which is mainly obtained by manual liposuction using a cannula linked to a syringe. However, in the past years, a number of devices for fat liposuction intended for clinical use have been commercialized but few papers have compared these procedures in terms of stromal vascular fraction (SVF) or adipose mesenchymal stromal cells (ASC). The objective of the present study was to compare and qualify for clinical use the ASC obtained from fat isolated with the manual or the Bodyjet(®) water-jet-assisted procedure. Although the initial number of cells obtained after collagenase digestion was higher with the manual procedure, the percentage of dead cells, the number of colony forming unit-fibroblast and the phenotype of cells were identical in the SVF at isolation (day 0) and in the ASC populations at day 14. We also showed that the osteogenic and adipogenic differentiation potentials of ASCs were identical between preparations while a slight but significant higher in vitro immunosuppressive effect was observed with ASCs isolated from fat removed with a cannula. The difference in the immunomodulatory effect between ASC populations was, however, not observed in vivo using the delayed-type hypersensitivity (DTH) model. Our data, therefore, indicate that the procedure for fat liposuction does not impact the characteristics or the therapeutic function of ASCs.