IL-4 gene therapy for collagen arthritis suppresses synovial IL-17 and osteoprotegerin ligand and prevents bone erosion

Rheumatoid Synovial Fluid and Acidic Extracellular pH Modulate the Immunomodulatory Activity of Urine-Derived Stem Cells

Urine-derived stem cells (UdSCs) possess a remarkable anti-inflammatory and immune-modulating activity. However, the clinical significance of UdSCs in autoimmune inflammatory diseases such as rheumatoid arthritis (RA) is yet to be explored. Hence, we tested the UdSCs response to an articular RA microenvironment. To simulate the inflamed RA joint more authentically in vitro, we treated cells with rheumatoid synovial fluids (RASFs) collected from RA patients, serum deprivation, acidosis (pH 7.0 and 6.5), and their combinations. Firstly, the RASFs pro-inflammatory status was assessed by cytokine quantification. Then, UdSCs were exposed to the RA environmental factors for 48 h and cell proliferation, gene expression and secretion of immunomodulatory factors were evaluated. The immunosuppressive potential of pre-conditioned UdSCs was also assessed via co-cultivation with activated peripheral blood mononuclear cells (PBMCs). In all experimental conditions, UdSCs' proliferation was not affected. Conversely, extracellular acidosis considerably impaired the viability/proliferation of adipose tissue-derived stem cells (ATSCs). In the majority of cases, exposure to RA components led to the upregulated expression of IL-6, TSG6, ICAM-1, VCAM-1, and PD-L1, all involved in immunomodulation. Upon RASFs and acidic stimulation, UdSCs secreted higher levels of immunomodulatory cytokines: IL-6, IL-8, MCP-1, RANTES, GM-CSF, and IL-4. Furthermore, RASFs and combined pretreatment with RASFs and acidosis promoted the UdSCs-mediated immunosuppression and the proliferation of activated PBMCs was significantly inhibited. Altogether, our data indicate that the RA microenvironment certainly has the capacity to enhance UdSCs' immunomodulatory function. For potential preclinical/clinical applications, the intra-articular injection might be a reasonable approach to maximize UdSCs' therapeutic efficiency in the RA treatment.

Interleukin-4 as a therapeutic target

Interleukin-4 (IL-4) is a pleiotropic cytokine mainly known for its role in type 2 immunity. Therapies antagonizing or blocking IL-4 activity have been developed to counteract diseases such as atopic dermatitis and asthma. In contrast, other disorders experimentally benefit from IL-4-related effects and IL-4 recently demonstrated beneficial activity in experimental stroke, spinal cord injury and the animal model of multiple sclerosis. To exploit IL-4-related activity for therapeutic concepts, current experimental efforts include modifying the pathway without inducing type 2 immune response and targeting of the cytokine to specific tissues. Here, we review different activities of IL-4 as well as therapeutic strategies.

Characterization of the Secretome of a Specific Cell Expressing Mutant Methionyl-tRNA Synthetase in Co-Culture Using Click Chemistry

Co-culture system, in which two or more distinct cell types are cultured together, is advantageous in that it can mimic the environment of the in vivo niche of the cells. In this study, we presented a strategy to analyze the secretome of a specific cell type under the co-culture condition in serum-supplemented media. For the cell-specific secretome analysis, we expressed the mouse mutant methionyl-tRNA synthetase for the incorporation of the non-canonical amino acid, azidonorleucine into the newly synthesized proteins in cells of which the secretome is targeted. The azidonorleucine-tagged secretome could be enriched, based on click chemistry, and distinguished from any other contaminating proteins, either from the cell culture media or the other cells co-cultured with the cells of interest. In order to have more reliable true-positive identifications of cell-specific secretory bodies, we established criteria to exclude any identified human peptide matched to bovine proteins. As a result, we identified a maximum of 719 secreted proteins in the secretome analysis under this co-culture condition. Last, we applied this platform to profile the secretome of mesenchymal stem cells and predicted its therapeutic potential on osteoarthritis based on secretome analysis.

Cell-based therapies for rheumatoid arthritis: opportunities and challenges

Rheumatoid arthritis (RA) is the most common immune-mediated inflammatory disease characterized by chronic synovitis that hardly resolves spontaneously. The current treatment of RA consists of nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, conventional disease-modifying antirheumatic drugs (cDMARDs), biologic and targeted synthetic DMARDs. Although the treat-to-target strategy has been intensively applied in the past decade, clinical unmet needs still exist since a substantial proportion of patients are refractory or even develop severe adverse effects to current therapies. In recent years, with the deeper understanding of immunopathogenesis of the disease, cell-based therapies have exhibited effective and promising interventions to RA. Several cell-based therapies, such as mesenchymal stem cells (MSC), adoptive transfer of regulatory T cells (Treg), and chimeric antigen receptor (CAR)-T cell therapy as well as their beneficial effects have been documented and verified so far. In this review, we summarize the current evidence and discuss the prospect as well as challenges for these three types of cellular therapies in RA.

Th2 IL-4/IL-13 dual blockade with Dupilumab is linked to some Emergent Th17 type Diseases including seronegative arthritis, enthesitis/enthesopathy, but not humoral autoimmune diseases

Dupilumab, an IL-4/IL-13 receptor blocker, has been linked to emergent seronegative inflammatory arthritis and psoriasis that form part of the spondyloarthropathy (SpA) spectrum. We systematically investigated patterns of immune disorders including predominantly Th17- (SpA pattern), Th2-mediated disorders and humoral autoimmune pattern diseases, using VigiBase, the World Health Organization's (WHO) global pharmacovigilance of adverse drug reactions (ADRs). Several bioinformatics databases and repositories were mined to couple Dupilumab-related immune-pharmacovigilance with molecular cascades relevant to reported findings. 37,848 Dupilumab ADR cases were reported, with skin, eye, musculoskeletal systems most affected. Seronegative arthritis (OR 9.61) psoriasis (OR 1.48), enthesitis/enthesopathy (OR 12.65), and iridocyclitis (OR 3.77) were highly associated. However, Ankylosing Spondylitis and IBD were not conclusively associated. Overall, classic polygenic humorally-mediated autoimmune diseases such as RA and SLE were not associated with Dupilumab use. Pathway analysis identified several biological pathways potentially involved in Dupilumab-associated ADRs, including the fibroblast growth factor receptor (FGFR; in particular, FGFR2) pathway. miRNAs analysis revealed the potential involvement of hsa-miR-21-5p and hsa-miR-335-5p. In conclusion, IL-4/IL-13 blockers are not unexpectedly protective against humoral autoimmune diseases but dynamically skew immune responses towards some IL-23/IL-17 cytokine pathway-related diseases. A robust signal potentially towards degenerative related pathology in the eye and vasculature due to loss of IL-4/IL-13 tissue reparative homeostatic mechanisms emerged.

Interleukin-4-carrying small extracellular vesicles with a high potential as anti-inflammatory therapeutics based on modulation of macrophage function

Interleukin-4 (IL4), a Th2-type cytokine that can drive M2 macrophage polarization, is expected to be used as an anti-inflammatory therapy agent as M2 polarization of macrophages can ameliorate chronic inflammation. However, several problems, such as the low effectiveness and side effects, have hampered the clinical application. To safely and effectively use IL4, an efficient delivery of IL4 to target cells, macrophages, is necessary. Small extracellular vesicles (sEVs) are promising candidates as macrophage delivery carriers because they are efficiently recognized by macrophages. In addition, considering the property of IL4 signaling, for which the internalization of IL4 receptor into the cellular compartment is important, and sEV uptake mechanism by macrophages, sEVs are expected to amplify IL4 signaling. In this study, we developed IL4-carrying sEVs (IL4-sEVs) by genetically engineering sEV-producing cells. We investigated the bioactivity of IL4-sEVs using RAW264.7 macrophages and their potential for therapeutic application to the treatment of an inflammatory disease using collagen-induced arthritis model mice. IL4-sEVs exhibited stronger anti-inflammatory effects on M1-polarized macrophages through M2 polarization of macrophages than those of soluble IL4 proteins. Moreover, IL4-sEVs exhibited more effective therapeutic effects on rheumatoid arthritis than those of IL4. These results indicate that IL4-carrying sEVs are promising anti-inflammatory therapeutics.

Expression of mBD4, mBD3 and CRAMP during type II collagen-induced arthritis/CIA and their association with inflammation and bone-remodeling markers

The aim of this study was to analyze the expression of mBD4, mBD3 and CRAMP in joint of mice with type II collagen-induced arthritis/CIA and to explore its possible association with IL-10, IL-4, IFN-γ, IL-17, MMP3, RANK/RANKL/OPG and histological parameters.

METHODS

CIA was induced in 44 DBA/1 J mice. The joints from mice were classified into the onset, peak and remission phase of CIA. Histological sections were stained with hematoxylin-eosin and safranin O. The expression of CRAMP, mBD-3, mBD-4, and MMP-3 was evaluated using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry. The expression of IL-10, IL-4, IFN-γ, IL-17, RANK/RANKL/OPG was analyzed by RT-PCR.

RESULTS

We observed that inflammation and immunostained cells for CRAMP increased in the peak and remission phases compared to the control group. In addition, increments in relative expressions of CRAMP were detected for the remission phase and in IL-4 and IL-17 in the peak phase compared to the control and onset phase. In addition, an increase in IL-10 in a peak phase compared to the control, as well as the relative expression of IFN-γ in remission phase was higher than in the onset phase. This was accompanied by an increase in cartilage damage in the peak phase compared to the control. Cells immunostained to MMP3 increased in the peak phase compared to the onset and control group, and relative expression of MMP3 was detected in the peak phase compared to the onset, remission, and control group. We observed that the relative expression of RANK and RANKL in the peak phase was higher than in control and onset phase. Finally, the relative expression of OPG in the peak phase compared to the onset, remission, and control group was detected. Regarding CRAMP behavior in the different phases studied, it was positively correlated with IL-4 and RANK, and showed a negative correlation with IFN-γ, IL-17, IL-10, RANKL, OPG and RANKL/OPG ratio in the control group. Also was positively correlated with IFN-γ, IL-17, IL-4, IL-10, as well as with RANK, RANKL, and OPG in the onset and peak phases of the CIA. In the peak phase, CRAMP showed a positive association with MMP3, and we observed a direct correlation between CRAMP and IFN-γ and RANKL/OPG ratio in remission phase. mBD3 correlates positively with IFN-γ, IL-17, IL-10, RANKL, OPG and RANKL/OPG ratio, and showed a negative correlation with CRAMP, MMP3, and RANK in the control group. Also, it was directly associated with IFN-γ, IL-17, IL-4, IL-10 and RANKL in the onset phase while it was inversely associated with CRAMP, MMP-3, RANK, RANKL, and OPG in the peak phase. Finally, mBD3 was inversely correlated with MMP3 in the remission phase and was directly associated with CRAMP, IFN-γ and RANKL/OPG ratio in this phase. mBD4 was directly associated with CRAMP, IFN-γ, IL-17, IL-4, IL-10, RANKL / OPG in the onset phase, and with CRAMP, IFN-γ, IL-17, IL-4, IL-10, MMP3, RANK, RANKL and OPG in the peak phase. Finally, mBD4 was positively associated with mBD3, IFN-γ, IL-17, IL-10, RANK, RANKL OPG and RANKL/OPG in the CIA remission phase.

CONCLUSIONS

Our results demonstrate that CRAMP plays an important role in CIA progress and suggest that its abundance is associated with local pro- and anti-inflammatory status. This makes us propose CRAMP as a possible contributor of bone reconstruction in the last stage of CIA.

Regulation of entheseal IL-23 expression by IL-4 and IL-13 as an explanation for arthropathy development under dupilumab therapy

OBJECTIVES

Dupilumab blocks the IL-4 receptor (IL-4R) and thus signalling of the 'Th2' cytokines IL-4 and IL-13. It has a license to treat atopic eczema and was recently linked to emergent enthesitis and psoriasis. We investigated the cellular and functional basis for how IL-4/IL-13 regulates the IL-23-IL-17 axis in entheseal stromal, myeloid and lymphocyte cells.

METHODS

Immunohistochemistry was performed on healthy enthesis samples from patients undergoing elective spinal surgery to investigate entheseal tissue IL-4R expression and cytokine expression by intracellular flow cytometry for IL-4 and IL-13. Digested human enthesis samples were stimulated with lipopolysaccharide (LPS) for IL-23 induction, either alone or with IL-4 or IL-13. Enthesis fibroblasts were stimulated with TNF and IL-17 with and without IL-4 or IL-13 to assess the effect on CCL20 secretion. Synovial fluid samples from PsA patients were also analysed by ELISA for levels of IL-4 and IL-13.

RESULTS

The IL-4/IL-13 receptor was present in both the peri-entheseal bone and enthesis soft tissue, and entheseal-derived T cells produced basal levels of IL-4, but not IL-13. Both IL-4 and IL-13 attenuated LPS-induced entheseal IL-23 production. IL-4 also downregulated secretion of TNF/IL-17A-induced CCL20 from entheseal fibroblasts. Both IL-13 and IL-4 were also detectable in the synovial fluid of PsA patients. We also noted a seronegative inflammatory oligoarthritis whilst under dupilumab therapy.

CONCLUSION

Our findings suggest a previously unknown protective role for IL-4/IL-13 in entheseal induction of the IL-23-IL-17 axis. These findings point towards a novel explanation for IL-13 pathway single nucleotide polymorphisms in PsA and also a molecular explanation for why anti-IL-4/IL-13 therapy may induce musculoskeletal entheseal pathology as recently reported.

Cytokine "fine tuning" of enthesis tissue homeostasis as a pointer to spondyloarthritis pathogenesis with a focus on relevant TNF and IL-17 targeted therapies

A curious feature of axial disease in ankylosing spondylitis (AS) and related non-radiographic axial spondyloarthropathy (nrAxSpA) is that spinal inflammation may ultimately be associated with excessive entheseal tissue repair with new bone formation. Other SpA associated target tissues including the gut and the skin have well established paradigms on how local tissue immune responses and proven disease relevant cytokines including TNF and the IL-23/17 axis contribute to tissue repair. Normal skeletal homeostasis including the highly mechanically stressed entheseal sites is subject to tissue microdamage, micro-inflammation and ultimately repair. Like the skin and gut, healthy enthesis has resident immune cells including ILCs, γδ T cells, conventional CD4+ and CD8+ T cells and myeloid lineage cells capable of cytokine induction involving prostaglandins, growth factors and cytokines including TNF and IL-17 that regulate these responses. We discuss how human genetic studies, animal models and translational human immunology around TNF and IL-17 suggest a largely redundant role for these pathways in physiological tissue repair and homeostasis. However, disease associated immune system overactivity of these cytokines with loss of tissue repair “fine tuning” is eventually associated with exuberant tissue repair responses in AS. Conversely, excessive biomechanical stress at spinal enthesis or peripheral enthesis with mechanically related or degenerative conditions is associated with a normal immune system attempts at cytokine fine tuning, but in this setting, it is commensurate to sustained abnormal biomechanical stressing. Unlike SpA, where restoration of aberrant and excessive cytokine “fine tuning” is efficacious, antagonism of these pathways in biomechanically related disease may be of limited or even no value.

Cytokines and Bone: Osteoimmunology

Cytokines and hematopoietic growth factors have traditionally been thought of as regulators of the development and function of immune and blood cells. However, an ever-expanding number of these factors have been discovered to have major effects on bone cells and the development of the skeleton in health and disease (Table 1). In addition, several cytokines have been directly linked to the development of osteoporosis in both animal models and in patients. In order to understand the mechanisms regulating bone cells and how this may be dysregulated in disease states, it is necessary to appreciate the diverse effects that cytokines and inflammation have on osteoblasts, osteoclasts, and bone mass. This chapter provides a broad overview of this topic with extensive references so that, if desired, readers can access specific references to delve into individual topics in greater detail.

[The impact of disbalance of regulatory cytokines and osteocalcin on osteogenesis in children with congenital cleft lip and palate in postnatal ontogenesis]

The aim of the work was a comprehensive assessment of the system of cytokines and peripheral blood osteocalcin with the establishment of features of their interconnections in children with congenital cleft lip and palate (CCLP) in comparison with the corresponding controls at different age periods. In the peripheral blood of 80 children (0-12 months, 1-3 years, 4-9 years, 10-15 years) with osteocalcin and IL17, IL4, congenital cleft lip and palate and age-appropriate control of healthy individuals (40 people) IL6, IL1β, IFNγ by enzyme immunoassay. An analysis of the data obtained with CCLP revealed significant differences in the dynamics of the relationship between pro-inflammatory (IL1β, IL6, IL17), regulatory (IFNγ), anti-inflammatory (IL4) cytokines and osteocalcin compared with controls. The patterns of changes and effects of IL17, IFNγ, IL4 and osteocalcin in healthy children and in children with congenital cleft lip and palate in postnatal ontogenesis were established. Cytokine dysregulation of immunosteogenesis in CCLP, leading to a significant deficit of osteocalcin in the first year of life due to an imbalance of the cytokine profile: discordant IL17, IFNγ and IL4 were detected. Thus, the data obtained are undoubtedly important in the future for developing new strategies for targeted therapy aimed at normalizing osteocalcin levels at different age periods in children with congenital cleft lip and palate.

Activation of RXR by bexarotene inhibits inflammatory conditions in human rheumatoid arthritis fibroblast‑like synoviocytes

Rheumatoid arthritis (RA) is a debilitating joint disease characterized by chronic inflammation, pathologic alteration of fibroblast‑like synoviocytes (FLS), destruction of cartilage and bone, and the formation of an invasive pannus. RA‑FLS exhibit increased proliferation and resistance to apoptosis. The retinoid X receptor (RXR) has a role in regulating cell cycle, differentiation and apoptosis, and agonism of RXR has been investigated as a treatment strategy in several types of cancer. However, there is little research on the effects of RXR agonism in other diseases. Bexarotene is a novel selective RXR ligand used in the treatment of T‑cell lymphoma. In the present study, bexarotene was used to investigate the involvement of RXR in tumor necrosis factor‑α (TNF‑α)‑induced RA conditions in human FLS. To the best of our knowledge, this is the first time that RXR has been demonstrated to be expressed in FLS and to be downregulated in response to TNF‑α stimulation. The present study also demonstrated that bexarotene exerted an anti‑inflammatory effect by downregulating expression of interleukin (IL)‑6, IL‑8, monocyte chemoattractant protein‑1, and high mobility group box‑1. Notably, bexarotene also rescued the TNF‑α‑induced downregulation of the anti‑inflammatory cytokines IL‑4 and transforming growth factor‑β1. Bexarotene treatment exhibited a potential protective effect against cartilage degradation by downregulating the expression of matrix metalloproteinase (MMP)‑1, MMP‑3 and MMP‑13. In addition, the present results demonstrated that the effects of bexarotene were mediated through the p38 mitogen‑activated protein kinase/nuclear factor‑κB pathway, via inhibition of p38 protein and the inhibitor α of κB phosphorylation. Taken together, the present findings demonstrated the potential of RXR agonism using bexarotene as a treatment against the development and progression of RA.

Combination Therapy of Mesenchymal Stromal Cells and Interleukin-4 Attenuates Rheumatoid Arthritis in a Collagen-Induced Murine Model

Rheumatoid arthritis (RA) is a disease of the joints that causes decreased quality of life. Mesenchymal stromal cells (MSCs) have immunosuppressive properties, with possible use in the treatment of RA. Similarly, interleukin (IL)-4 has been shown as a potential RA treatment. However, their combination has not been explored before. Therefore, this study aimed to investigate the effect of a combination therapy of MSCs and IL-4 in the treatment of RA, using a murine collagen-induced arthritis (CIA) model. Arthritis was induced in Balb/c mice by two intradermal injections of type II collagen (CII), at days 0 and 21. CIA mice were randomly assigned to four groups; group I received an intravenous injection of mouse bone marrow-derived MSCs, while group II received an intraperitoneal injection of IL-4. Group III received a combined treatment of MSC and IL-4, while group IV served as a CIA diseased control group receiving phosphate buffer saline (PBS). A fifth group of healthy mice served as the normal healthy control. To assess changes induced by different treatments, levels of RA-associated inflammatory cytokines and biomarkers were measured in the serum, knee joints, and synovial tissue, using ELISA and Real Time-qPCR. Histopathological features of knee joints were analyzed for all groups. Results showed that combined MSC and IL-4 treatment alleviated signs of synovitis in CIA mice, reverting to the values of healthy controls. This was evident by the decrease in the levels of rheumatic factor (RF), C-reactive protein (CRP) and anti-nuclear antibodies (ANA) by 64, 80, and 71%, respectively, compared to the diseased group. Moreover, tumor necrosis factor-alpha (TNF- α) and monocyte chemoattractant protein-1 (MCP-1) levels decreased by 63 and 68%, respectively. Similarly, our gene expression data showed improvement in mice receiving combined therapy compared to other groups receiving single treatment, where cartilage oligomeric matrix protein (Comp), tissue inhibitor metalloproteinase-1 (Timp1), matrix metalloproteinase1 (Mmp-1), and IL-1 receptor (Il-1r) gene expression levels decreased by 75, 70, and 78%, respectively. Collectively, treatment with a combined therapy of MSC and IL-4 might have an efficient therapeutic effect on arthritis. Thus, further studies are needed to assess the potential of different MSC populations in conjugation with IL-4 in the treatment of experimental arthritis.

Supramolecular Cyclodextrin-Based Hydrogels for Controlled Gene Delivery

Controlled delivery of gene transfer vectors is a powerful strategy to enhance the temporal and spatial presentation of therapeutic agents in a defined target. Hydrogels are adapted biomaterials for gene delivery capable of acting as a localized depot of genes while maintaining the long term local availability of DNA vectors at a specific location. Supramolecular hydrogels based on cyclodextrins (CDs) have attracted considerable attention as potential biomaterials in a broad range of drug delivery applications. Their unique characteristics of thixotropicity and low cytotoxicity due to their production under mild conditions make them potential candidates to form injectable delivery systems. This work aims to provide an overview of the use of CD-based polypseudorotaxane hydrogels as controlled gene delivery systems for different applications in regenerative medicine.

Macrophage immunomodulation in chronic osteolytic diseases-the case of periodontitis

Periodontitis (PD) is a chronic osteolytic disease that shares pathogenic inflammatory features with other conditions associated with nonresolving inflammation. A hallmark of PD is inflammation-mediated alveolar bone loss. Myeloid cells, in particular polymorphonuclear neutrophils (PMN) and macrophages (Mac), are essential players in PD by control of gingival biofilm pathogenicity, activation of adaptive immunity, as well as nonresolving inflammation and collateral tissue damage. Despite mounting evidence of significant innate immune implications to PD progression and healing after therapy, myeloid cell markers and targets for immune modulation have not been validated for clinical use. The remarkable plasticity of monocytes/Mac in response to local activation factors enables these cells to play central roles in inflammation and restoration of tissue homeostasis and provides opportunities for biomarker and therapeutic target discovery for management of chronic inflammatory conditions, including osteolytic diseases such as PD and arthritis. Along a wide spectrum of activation states ranging from proinflammatory to pro-resolving, Macs respond to environmental changes in a site-specific manner in virtually all tissues. This review summarizes the existing evidence on Mac immunomodulation therapies for osteolytic diseases in the broader context of conditions associated with nonresolving inflammation, and discusses osteoimmune implications of Macs in PD.

Gene therapy in rheumatoid arthritis: Strategies to select therapeutic genes

Significant advances have been achieved in recent years to ameliorate rheumatoid arthritis (RA) in animal models using gene therapy approaches rather than biological treatments. Although biological agents serve as antirheumatic drugs with suppressing proinflammatory cytokine activities, they are usually accompanied by systemic immune suppression resulting from continuous or high systemic dose injections of biological agents. Therefore, gene transfer approaches have opened an interesting perspective to deliver one or multiple genes in a target-specific or inducible manner for the sustained intra-articular expression of therapeutic products. Accordingly, many studies have focused on gene transferring methods in animal models by using one of the available approaches. In this study, the important strategies used to select effective genes for RA gene therapy have been outlined. Given the work done in this field, the future looks bright for gene therapy as a new method in the clinical treatment of autoimmune diseases such as RA, and by ongoing efforts in this field, we hope to achieve feasible, safe, and effective treatment methods.

Salivary gland secretome: a novel tool towards molecular stratification of patients with primary Sjögren's syndrome and non-autoimmune sicca

Objective

To explore the potential of salivary gland biopsy supernatants (the secretome) as a novel tool to aid in stratification of patients with sicca syndrome and to study local immunopathology in Sjögren’s syndrome.

Methods

Labial salivary gland biopsies were incubated in saline for 1 hour. In these tissue supernatants from a discovery cohort (n=16) of patients with primary Sjögren’s syndrome (pSS) and non-Sjögren’s sicca (nSS), 101 inflammatory mediators were measured by Luminex. Results were validated in a replication cohort (n=57) encompassing patients with pSS, incomplete SS and nSS.

Results

The levels of 23 cytokines were significantly increased in patients with pSS versus nSS in the discovery cohort. These 23 and 3 additional cytokines were measured in a second cohort. Elevated concentrations of 11 cytokines were validated and the majority correlated with clinical parameters. Classification tree analysis indicated that the concentrations of CXCL13, IL-21, sIL-2R and sIL-7Rα could be used to classify 95.8% of patients with pSS correctly.

Conclusion

Labial salivary gland secretomes can be used to reliably assess mediators involved in immunopathology of patients with pSS, potentially contributing to patient classification. As such, this method represents a novel tool to identify therapeutic targets and markers for diagnosis, prognosis and treatment response.

Targeted Reinforcement of Macrophage Reprogramming Toward M2 Polarization by IL-4-Loaded Hyaluronic Acid Particles

Alteration of macrophage polarization from inflammatory (M1) to anti-inflammatory (M2) phenotype can have striking implications for the regeneration of injured tissues, treatment of inflammatory diseases, and relief of autoimmune disorders. Although certain cytokines like interleukin (IL)-4 and IL-13 are capable of inducing M2 macrophage polarization, their therapeutic potential in vivo is suffering from low efficacy due to their instability and poor access to target cells. Here, we report the synthesis of IL-4-loaded hyaluronic acid (HA) particle for the targeted delivery of cytokines through the high affinity of HA to CD44 receptors of macrophages. HA carriers composed of low, middle, and high molecular weight (MW) polymers were synthesized using divinyl sulfone (DVS) cross-linking. The MW of HA had a negligible effect on the physicochemical properties and biocompatibility of the macrophages, but as an indicative of M2 polarization, a significant change in the arginase-1 (Arg-1) activity, TNF-α release, and IL-10 secretion was observed for the HA particles prepared with high MW polymers. Therefore, these particles were loaded with IL-4 for simultaneous macrophage targeting and M1 to M2 reprogramming, evidenced by a remarkable increase in the Arg-1 to iNOS ratio, as well as CD163 and CD206 upregulation in the M1 macrophages, which were initially triggered by lipopolysaccharide and interferon-γ.

Systemic treatment with resveratrol reduces the progression of experimental periodontitis and arthritis in rats

Rheumatoid arthritis and periodontitis are chronic inflammatory diseases which has been closely associated due to the nature of immune-inflammatory imbalance response. Resveratrol is a naturall product with biological proprieties that may promote immunomodulatory effects on host response. This study investigated resveratrol continuous administration effect on experimental periodontitis and arthritis progression in rats. Thirty-five rats were assigned to the following groups: 1-experimental arthritis + experimental periodontitis + placebo (RA+EP +PL) (n = 12); 2 -RA+EP+ ibuprofen (RA+PE+IB) (n = 11); 3-RA+EP+ resveratrol (RA+PE+RSV) (n = 11). After euthanasia, the specimens were processed for morphometric analysis of bone loss, and the gingival tissue surrounding the first molar was collected for quantification of inflammatory markers using a Luminex/MAGpix assay and anti-citrullinated protein antibody (ACCPA) levels were measured by ELISA assay. Serum level of rheumatoid factor (RF) was measured by ELISA assay. Paw edema was analyzed using a plethysmometer. Higher bone loss was observed in PL group, when compared to IB and RSV groups. RSV group presented higher IL-4 concentration than PL and IB groups. Resveratrol reduced RF serum levels and both IB and RSV decreased ACCPA gingival levels. Besides, paw swelling level was significantly lower in IB and RSV groups in the 21th day and only in RSV group in the 28th day. Histological analyzes showed smooth articular surface and higher width of the subchondral cortical in RSV group. Resveratrol showed modulatory effect and seems to reduce the inflammatory signs of arthritis and articular damage throughout the time.

Resolving Macrophages Counter Osteolysis by Anabolic Actions on Bone Cells

Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis, is characterized by increased production of proinflammatory mediators and matrix-degrading enzymes by macrophages and increased osteoclastic activity. Phenotypic changes in macrophages are central to the healing process in virtually all tissues. Using a murine model of periodontitis, we assessed the timing of macrophage phenotypic changes and the impact of proresolving activation during inflammatory osteolysis and healing. Proinflammatory macrophage activation and TNF-α overproduction within 3 wk after induction of periodontitis was associated with progressing bone loss. Proresolving activation within 1 wk of stimulus removal and markers of resolving macrophages (IL-10, TGF-β, and CD206) correlated strongly with bone levels. In vivo macrophage depletion with clodronate liposomes prevented bone resorption but impaired regeneration. Induction of resolving macrophages with rosiglitazone, a PPAR-γ agonist, led to reduced bone resorption during inflammatory stimulation and increased bone formation during healing. In vitro assessment of primary bone marrow-derived macrophages activated with either IFN-γ and LPS (proinflammatory activation) or IL-4 (proresolving activation) showed that IL-4-activated cells have enhanced resolving functions (production of anti-inflammatory cytokines; migration and phagocytosis of aged neutrophils) and exert direct anabolic actions on bone cells. Cystatin C secreted by resolving but not inflammatory macrophages explained, in part, the macrophage actions on osteoblasts and osteoclasts. This study supports the concept that therapeutic induction of proresolving functions in macrophages can recouple bone resorption and formation in inflammatory osteolytic diseases.

The combination of FK506 and an anti-CD147 mAb exerts potential therapeutic effects on a mouse model of collagen-induced arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, and excessive T lymphocyte activation plays a critical role in the development of inflammation. CD147 is an antigen related to T cell activation, CD147 blockade exerts beneficial effects on RA. FK506, also known as tacrolimus, exerts strong immunosuppressive effects by inhibiting T cell activation. In this study, RL73 (an anti-mouse CD147 functional-grade purified antibody) and FK506 were co-administered to mice with collagen-induced arthritis (CIA). As expected, the combination of these two drugs produced superior therapeutic effects than either drug alone and enabled the administration of each drug at a lower dose. Moreover, joint damage and destruction were significantly improved in mice injected with both FK506 and RL73 compared with mice injected with either agent alone. These effects might have been observed because the proportions of CD4 + T and CD8 + T cells in the mouse spleen of the combination regimen were clearly decreased compared with each monotherapy. In addition, the proportions of Th2 subsets in the mouse spleen and peripheral blood were clearly increased, and the serum levels of the cytokines interleukin 4 (IL-4) and IL-10 were markedly increased in mice treated with the combination therapy compared with the other groups of mice. The splenic total number of T lymphocytes also showed that the inhibition of T lymphocytes was the most obvious in the combined treatment group. Based on the results from the present study, combining FK506 and the anti-CD147 mAb might be a new practical therapeutic option for the treatment of RA.

Deficient invariant natural killer T cells had impaired regulation on osteoclastogenesis in myeloma bone disease

Recent research showed that invariant natural killer T (iNKT) cells take part in the regulation of osteoclastogenesis. While the role of iNKT cells in myeloma bone disease (MBD) remains unclear. In our study, the quantity of iNKT cells and the levels of cytokines produced by them were measured by flow cytometry. iNKT cells and osteoclasts were induced from peripheral blood mononuclear cells after activation by α‐GalCer or RANKL in vitro. Then, gene expressions and the levels of cytokines were determined by RT‐PCR and ELISA, respectively. The results showed that the quantity of iNKT and production of IFN‐γ by iNKT cells were significantly decreased in newly diagnosed MM (NDMM), and both negatively related with severity of bone disease. Then, the osteoclasts from healthy controls were cultured in vitro and were found to be down‐regulated after α‐GalCer‐stimulated, while there was no significant change with or without α‐GalCer in NDMM patients, indicating that the regulation of osteoclastogenesis by iNKT cells was impaired. Furthermore, the inhibition of osteoclastogenesis by iNKT cells was regulated by IFN‐γ production, which down‐regulated osteoclast‐associated genes. In conclusion, the role of α‐GalCer‐stimulated iNKT cells in regulation of osteoclastogenesis was impaired in MBD, as a result of iNKT cell dysfunction.

Regulation of Immune Function by Vitamin D and Its Use in Diseases of Immunity

Evidence exists for a role for vitamin D and its active metabolites in modulating immune functions. In animal models, vitamin D deficiency is associated with a higher risk for autoimmunity in genetically predisposed subjects and increases in susceptibility to infections. In addition, high-dose vitamin D can improve immune health, prevent autoimmunity, and improve defense against infections. In humans, evidence exists on associations between vitamin D deficiency and impaired immune function, leading to autoimmunity in genetically predisposed people and increased risk for infections; data on therapeutic immune effects of vitamin D supplementation when vitamin D levels are already sufficient are lacking.

Pharmacological Regulation of Neuropathic Pain Driven by Inflammatory Macrophages

Neuropathic pain can have a major effect on quality of life but current therapies are often inadequate. Growing evidence suggests that neuropathic pain induced by nerve damage is caused by chronic inflammation. Upon nerve injury, damaged cells secrete pro-inflammatory molecules that activate cells in the surrounding tissue and recruit circulating leukocytes to the site of injury. Among these, the most abundant cell type is macrophages, which produce several key molecules involved in pain enhancement, including cytokines and chemokines. Given their central role in the regulation of peripheral sensitization, macrophage-derived cytokines and chemokines could be useful targets for the development of novel therapeutics. Inhibition of key pro-inflammatory cytokines and chemokines prevents neuroinflammation and neuropathic pain; moreover, recent studies have demonstrated the effectiveness of pharmacological inhibition of inflammatory (M1) macrophages. Nicotinic acetylcholine receptor ligands and T helper type 2 cytokines that reduce M1 macrophages are able to relieve neuropathic pain. Future translational studies in non-human primates will be crucial for determining the regulatory mechanisms underlying neuroinflammation-associated neuropathic pain. In turn, this knowledge will assist in the development of novel pharmacotherapies targeting macrophage-driven neuroinflammation for the treatment of intractable neuropathic pain.

Extra-Large Pore Mesoporous Silica Nanoparticles for Directing in Vivo M2 Macrophage Polarization by Delivering IL-4

Over the past decade, mesoporous silica nanoparticles (MSNs) smaller than 200 nm with a high colloidal stability have been extensively studied for systemic drug delivery. Although small molecule delivery via MSNs has been successful, the encapsulation of large therapeutic biomolecules, such as proteins or DNA, is limited due to small pore size of the conventional MSNs obtained by soft-templating. Here, we report the synthesis of mesoporous silica nanoparticles with extra-large pores (XL-MSNs) and their application to in vivo cytokine delivery for macrophage polarization. Uniform, size-controllable XL-MSNs with 30 nm extra-large pores were synthesized using organic additives and inorganic seed nanoparticles. XL-MSNs showed significantly higher loadings for the model proteins with different molecular weights compared to conventional small pore MSNs. XL-MSNs were used to deliver IL-4, which is an M2-polarizing cytokine and very quickly degraded in vivo, to macrophages and polarize them to anti-inflammatory M2 macrophages in vivo. XL-MSNs induced a low level of reactive oxygen species (ROS) production and no pro-inflammatory cytokines in bone marrow-derived macrophages (BMDMs) and in mice injected intravenously with XL-MSNs. We found that the injected XL-MSNs were targeted to phagocytic myeloid cells, such as neutrophils, monocytes, macrophages, and dendritic cells. Finally, we demonstrated that the injection of IL-4-loaded XL-MSNs successfully triggered M2 macrophage polarization in vivo, suggesting the clinical potential of XL-MSNs for modulating immune systems via targeted delivery of various cytokines.

Mast cells in rheumatoid arthritis: friends or foes?

Mast cells are tissue-resident cells of the innate immunity, implicated in the pathogenesis of many autoimmune diseases, including rheumatoid arthritis (RA). They are present in synovia and their activation has been linked to the potentiation of inflammation in the course of RA. However, recent investigations questioned the role of mast cells in arthritis. In particular, animal models generated conflicting results, so that many of their pro-inflammatory, i.e. pro-arthritogenic functions, even though supported by robust experimental evidence, have been labelled as redundant. At the same time, a growing body of evidence suggests that mast cells can act as tunable immunomodulatory cells. These characteristics, not yet fully understood in the context of RA, could partially explain the inconsistent results obtained with experimental models, which do not account for the pro- and anti-inflammatory functions exerted in more chronic heterogeneous conditions such as RA. Here we present an overview of the current knowledge on mast cell involvement in RA, including the intriguing hypothesis of mast cells acting as subtle immunomodulatory cells and the emerging concept of synovial mast cells as potential biomarkers for patient stratification.

CD14++ CD16- monocytes are the main source of 11β-HSD type 1 after IL-4 stimulation

The anti-inflammatory actions of IL-4 are well established through earlier findings. However, the exact mechanism it uses to downregulate the pro-inflammatory cytokine production through monocytes and macrophages is poorly understood. In this study, we examined the effect of IL-4 in the induction of 11β-HSD1 in the two main classes of monocytes, CD14⁺⁺ CD16^- (CD14) and CD14⁺ CD16⁺ (CD16). Peripheral Blood Mononuclear Cells (PBMCs) were isolated from 17 healthy donors and were sorted into CD14 and CD16 subpopulations using cell sorting. Effect of IL-4 on 11β-HSD1-enzyme activity was measured in sorted and unsorted monocytes using Homogeneous Time-Resolved Fluorescence (HTRF) and M1/M2 polarization analysis was performed by flow cytometry. Our results indicate that CD14 cells are the major source of 11β-HSD1 enzyme after IL-4 stimulation and that M2 phenotype is not a pre-requisite for its synthesis.

Hydrogel-Based Controlled Delivery Systems for Articular Cartilage Repair

Delivery of bioactive factors is a very valuable strategy for articular cartilage repair. Nevertheless, the direct supply of such biomolecules is limited by several factors including rapid degradation, the need for supraphysiological doses, the occurrence of immune and inflammatory responses, and the possibility of dissemination to nontarget sites that may impair their therapeutic action and raise undesired effects. The use of controlled delivery systems has the potential of overcoming these hurdles by promoting the temporal and spatial presentation of such factors in a defined target. Hydrogels are promising materials to develop delivery systems for cartilage repair as they can be easily loaded with bioactive molecules controlling their release only where required. This review exposes the most recent technologies on the design of hydrogels as controlled delivery platforms of bioactive molecules for cartilage repair.

The Relationship of Cytokines IL-13 and IL-17 with Autoantibodies Profile in Early Rheumatoid Arthritis

Aims. In the present study, we aimed to assess the concentrations of IL-13 and IL-17 in serum of patients with early rheumatoid arthritis (eRA), the investigation of correlation between the concentrations of these cytokines and disease activity score, and the concentration of some autoantibodies and the evaluation of the utility of IL-13 and -17 concentration measurements as markers of disease activity. Materials and Methods. Serum samples were collected from 30 patients and from 28 controls and analysed parameters. Results. The serum concentrations of IL-13, IL-17, anti-CCP, and IgM-RF were statistically significantly higher in patients with eRA, compared to the controls. IL-13 concentrations in the severe and moderate groups with eRA were statistically higher than in the mild and control groups. Also, in the case of IL-17, serum concentrations increased proportionally with the disease activity of eRA. We observe that concentrations of IL-13 and -17 did not correlate with autoantibodies. IL-17 concentration significantly positively correlated with CRP, while IL-13 concentration significantly negatively correlated with CRP. Disease activity score, DAS28, was strongly positively correlated with levels of ESR and weakly positively correlated with concentrations of anti-RA33 autoantibodies. IL-13 has a higher diagnostic utility than IL-17, CRP, ESR, IgM-RF, and anti-CCP as markers of disease activity. Conclusions. The presence of higher IL-13 and IL-17 serum levels in patients, compared with those of controls, confirms that these markers, found with high specificity, might be involved in the pathogenesis of eRA. IL-13 and IL-17 might be of better usefulness in the prediction of eRA activity status than IgM-RF and anti-CCP.

Epidermal Neuromedin U Attenuates IgE-Mediated Allergic Skin Inflammation

Although keratinocyte-derived neuropeptide neuromedin U (NMU) mediates the proinflammatory effects of innate-type mast cell activation, no information is available on the physiological roles. Here, to investigate the effects of NMU on IgE-mediated allergic skin inflammation, we determined whether IgE-mediated inflammation associated with severe scratching was induced in Nmu-/- mice administered repeated hapten applications to the ear or footpad. Dry skin was induced by targeted deletion of Nmu. Mice administered repeated hapten application developed IgE-mediated allergic inflammation characterized by severe scratching and increased serum IgE levels only when the ear, and not the footpad, was subjected to scratching, indicating that depletion of NMU from the epidermis alone does not drive such allergic inflammation. Thus, the susceptibility of Nmu-/- mice to allergic inflammation depends primarily on scratching dry skin. Further, allergic skin inflammation mediated by FcεRI cross-linking in Nmu-/-mice was inhibited by prior injection of NMU. These results indicate that NMU plays an important physiological role as a negative regulator during the late stage of IgE-mediated allergic skin inflammation.

Targeted IL-4 therapy synergizes with dexamethasone to induce a state of tolerance by promoting Treg cells and macrophages in mice with arthritis

F8-IL-4 is a recently developed immunocytokine that delivers IL-4 to sites of inflammation by targeting the neovasculature. We previously reported that F8-IL-4, in combination with dexamethasone (DXM), provides a durable therapy in mice with collagen-induced arthritis (CIA). Therefore, the objective of this study was to identify the mechanism by which IL-4 and DXM combination therapy provides long-lasting disease remission. F8-IL-4 alone attenuated inflammation in CIA and this was associated with increased TH 2 and decreased TH 17 cell numbers in the joints. Similarly, DXM alone had an antiinflammatory effect associated with lower TH 17 cell numbers. In both cases, these therapeutic benefits were reversed once treatment was stopped. On the other hand, combination therapy with F8-IL-4 plus DXM led to a synergistic increase in the percentage of regulatory T (Treg) cells and antiinflammatory macrophages in the arthritic joint and spleen as well as IL-10 levels in serum and spleen. The net result of this was a more pronounced attenuation of inflammation and, more importantly, protection from arthritis relapse post therapy retraction. In conclusion, F8-IL-4 plus DXM is a durable treatment for arthritis that acts by promoting Treg cells in a synergistic manner, and by producing a sustained increase in antiinflammatory macrophages.

Dysregulated osteoclastogenesis is related to natural killer T cell dysfunction in rheumatoid arthritis

OBJECTIVE

To investigate the role played by natural killer T (NKT) cells in osteoclastogenesis and their effects on inflammatory bone destruction.

METHODS

Patients with rheumatoid arthritis (RA) (n = 25) and healthy controls (n = 12) were enrolled in this study. In vitro osteoclastogenesis experiments were performed using peripheral blood mononuclear cells (PBMCs) in the presence of macrophage colony-stimulating factor and RANKL. PBMCs were cultured in vitro with α-galactosylceramide (αGalCer), and proliferation indices of NKT cells were estimated by flow cytometry. In vivo effects of αGalCer-stimulated NKT cells on inflammation and bone destruction were determined in mice with collagen-induced arthritis.

RESULTS

In vitro osteoclastogenesis was found to be significantly inhibited by αGalCer in healthy controls but not in RA patients. Proliferative responses of NKT cells and STAT-1 phosphorylation in monocytes in response to αGalCer were impaired in RA patients. Notably, αGalCer-stimulated NKT cells inhibited osteoclastogenesis mainly via interferon-γ production in a cytokine-dependent manner (not by cell-cell contact) and down-regulated osteoclast-associated genes. Mice treated with αGalCer showed less severe arthritis and reduced bone destruction. Moreover, proinflammatory cytokine expression in arthritic joints was found to be reduced by αGalCer treatment.

CONCLUSION

This study primarily demonstrates that αGalCer-stimulated NKT cells have a regulatory effect on osteoclastogenesis and a protective effect against inflammatory bone destruction. However, it also shows that these effects of αGalCer are diminished in RA patients and that this is related to NKT cell dysfunction. These findings provide important information for those searching for novel therapeutic strategies to prevent bone destruction in RA.

Enigma of IL-17 and Th17 Cells in Rheumatoid Arthritis and in Autoimmune Animal Models of Arthritis

Rheumatoid arthritis (RA) is one of the most common autoimmune disorders characterized by the chronic and progressive inflammation of various organs, most notably the synovia of joints leading to joint destruction, a shorter life expectancy, and reduced quality of life. Although we have substantial information about the pathophysiology of the disease with various groups of immune cells and soluble mediators identified to participate in the pathogenesis, several aspects of the altered immune functions and regulation in RA remain controversial. Animal models are especially useful in such scenarios. Recently research focused on IL-17 and IL-17 producing cells in various inflammatory diseases such as in RA and in different rodent models of RA. These studies provided occasionally contradictory results with IL-17 being more prominent in some of the models than in others; the findings of such experimental setups were sometimes inconclusive compared to the human data. The aim of this review is to summarize briefly the recent advancements on the role of IL-17, particularly in the different rodent models of RA.

Type 2 cytokines: mechanisms and therapeutic strategies

Type 2 immune responses are defined by the cytokines interleukin-4 (IL-4), IL-5, IL-9 and IL-13, which can either be host protective or have pathogenic activity. Type 2 immunity promotes antihelminth immunity, suppresses type 1-driven autoimmune disease, neutralizes toxins, maintains metabolic homeostasis, and regulates wound repair and tissue regeneration pathways following infection or injury. Nevertheless, when type 2 responses are dysregulated, they can become important drivers of disease. Type 2 immunity induces a complex inflammatory response characterized by eosinophils, mast cells, basophils, type 2 innate lymphoid cells, IL-4-and/or IL-13-conditioned macrophages and T helper 2 (TH2) cells, which are crucial to the pathogenesis of many allergic and fibrotic disorders. As chronic type 2 immune responses promote disease, the mechanisms that regulate their maintenance are thought to function as crucial disease modifiers. This Review discusses the many endogenous negative regulatory mechanisms that antagonize type 2 immunity and highlights how therapies that target some of these pathways are being developed to treat type 2-mediated disease.

Type 2 cytokines: mechanisms and therapeutic strategies

Type 2 immune responses are defined by the cytokines interleukin-4 (IL-4), IL-5, IL-9 and IL-13, which can either be host protective or have pathogenic activity. Type 2 immunity promotes antihelminth immunity, suppresses type 1-driven autoimmune disease, neutralizes toxins, maintains metabolic homeostasis, and regulates wound repair and tissue regeneration pathways following infection or injury. Nevertheless, when type 2 responses are dysregulated, they can become important drivers of disease. Type 2 immunity induces a complex inflammatory response characterized by eosinophils, mast cells, basophils, type 2 innate lymphoid cells, IL-4-and/or IL-13-conditioned macrophages and T helper 2 (TH2) cells, which are crucial to the pathogenesis of many allergic and fibrotic disorders. As chronic type 2 immune responses promote disease, the mechanisms that regulate their maintenance are thought to function as crucial disease modifiers. This Review discusses the many endogenous negative regulatory mechanisms that antagonize type 2 immunity and highlights how therapies that target some of these pathways are being developed to treat type 2-mediated disease.

IL-4/CCL22/CCR4 axis controls regulatory T-cell migration that suppresses inflammatory bone loss in murine experimental periodontitis

Inflammatory bone resorption is a hallmark of periodontitis, and Tregs and Th2 cells are independently associated with disease progression attenuation. In this study, we employed an infection-triggered inflammatory osteolysis model to investigate the mechanisms underlying Treg and Th2 cell migration and the impact on disease outcome. Aggregatibacter actinomycetemcomitans-infected C57Bl/6 (wild-type [WT]) mice develop an intense inflammatory reaction and alveolar bone resorption, and Treg and Th2 cell migration is temporally associated with disease progression attenuation. Tregs extracted from the lesions preferentially express CCR4 and CCR8, whereas Th2 cells express CCR3, CCR4, and CCR8. The absence of CCR5 and CCR8 did not significantly impact the migration of Tregs and Th2 cells or affect the disease outcome. CCR4KO mice presented a minor reduction in Th2 cells in parallel with major impairment of Treg migration, which was associated with increased inflammatory bone loss and higher proinflammatory and osteoclastogenic cytokine levels. The blockade of the CCR4 ligand CCL22 in WT mice resulted in an increased inflammatory bone loss phenotype similar to that in the CCR4KO strain. Adoptive transfer of CCR4(+) Tregs to the CCR4KO strain revert the increased disease phenotype to WT mice-like levels; also, the in situ production of CCL22 in the lesions is mandatory for Tregs migration and the consequent bone loss arrest. The local release of exogenous CCL22 provided by poly(lactic-co-glycolic acid) (PLGA) microparticles promotes migration of Tregs and disease arrest in the absence of endogenous CCL22 in the IL-4KO strain, characterized by the lack of endogenous CCL22 production, defective migration of Tregs, and exacerbated bone loss. In summary, our results show that the IL-4/CCL22/CCR4 axis is involved in the migration of Tregs to osteolytic lesion sites, and attenuates development of lesions by inhibiting inflammatory migration and the production of proinflammatory and osteoclastogenic mediators.

Relation between bone mineral density and IL-17 serum levels in Serbian patients with early Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial inflammation and destruction of joint cartilage and bone. Different cytokines play important role in the processes that cause articular destruction and extra-articular manifestations in RA. The contribution of cytokines representing the Th1 (INF-γ), Th2 (IL-4) and IL-17A to the pathogenesis of early RA and bone mineral density (BMD) loss in still poorly understood. Serum samples of 38 early RA patients were evaluated for erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), C-reactive protein (CRP), anti-cyclic citrullinated peptide antibodies (anti-CCP) and for the tested cytokines (IL-17A, IL-4 and INF-γ). BMD was evaluated by dualenergy X-ray absorptiometry (DXA). Disease activity score (DAS28) calculation was assessed for all patients. Control serum samples were obtained from 34 healthy volunteers. The levels of tested cytokines were significantly higher (IL-17A, p<0.001; INF-γ, P<0.001; IL-4, P<0.01) in patients with early RA, compared to the healthy controls. In early RA patients, strong correlation of serum IL-17A was found with DAS28, ESR and CRP. Also, a significant negative correlation was found between serum INF-γ levels and the DAS28 score. Significantly positive correlation of BMD values and CRP, DAS28 IL-17A were also demonstrated. DXA analysis revealed that the most common site for osteoporosis was the lumbar spine followed by the femoral neck. BMD values significantly correlated with CRP, DAS28 score and IL-17A serum levels. The mean serum IL-17A levels, in patients with early RA, corresponded with disease activity, severity and BMD loss, indicating the potential usefulness of serum IL-17A in defining the disease activity and bone remodeling.

mTOR inhibition rescues osteopenia in mice with systemic sclerosis

Chen et al. show that treatment with rapamycin, a drug known to inhibit mTOR signaling, rescues low bone density in mice with systemic sclerosis.

Fibrillin-1 (FBN1) deficiency-induced systemic sclerosis is attributed to elevation of interleukin-4 (IL4) and TGF-β, but the mechanism underlying FBN1 deficiency–associated osteopenia is not fully understood. We show that bone marrow mesenchymal stem cells (BMMSCs) from FBN1-deficient (Fbn1^+/−) mice exhibit decreased osteogenic differentiation and increased adipogenic differentiation. Mechanistically, this lineage alteration is regulated by IL4/IL4Rα-mediated activation of mTOR signaling to down-regulate RUNX2 and up-regulate PPARγ2, respectively, via P70 ribosomal S6 protein kinase (P70S6K). Additionally, we reveal that activation of TGF-β/SMAD3/SP1 signaling results in enhancement of SP1 binding to the IL4Rα promoter to synergistically activate mTOR pathway in Fbn1^+/− BMMSCs. Blockage of mTOR signaling by osteoblastic-specific knockout or rapamycin treatment rescues osteopenia phenotype in Fbn1^+/− mice by improving osteogenic differentiation of BMMSCs. Collectively, this study identifies a previously unrecognized role of the FBN1/TGF-β/IL4Rα/mTOR cascade in BMMSC lineage selection and provides experimental evidence that rapamycin treatment may provide an anabolic therapy for osteopenia in Fbn1^+/− mice.

IL-4 and IL-13 inhibit IL-1β and TNF-α induced kinin B1 and B2 receptors through a STAT6-dependent mechanism

BACKGROUND AND PURPOSE

Bone resorption induced by interleukin-1β (IL-1β) and tumour necrosis factor (TNF-α) is synergistically potentiated by kinins, partially due to enhanced kinin receptor expression. Inflammation-induced bone resorption can be impaired by IL-4 and IL-13. The aim was to investigate if expression of B1 and B2 kinin receptors can be affected by IL-4 and IL-13.

EXPERIMENTAL APPROACH

We examined effects in a human osteoblastic cell line (MG-63), primary human gingival fibroblasts and mouse bones by IL-4 and IL-13 on mRNA and protein expression of the B1 and B2 kinin receptors. We also examined the role of STAT6 by RNA interference and using Stat6(-/-) mice.

KEY RESULTS

IL-4 and IL-13 decreased the mRNA expression of B1 and B2 kinin receptors induced by either IL-1β or TNF-α in MG-63 cells, intact mouse calvarial bones or primary human gingival fibroblasts. The burst of intracellular calcium induced by either bradykinin (B2 agonist) or des-Arg(10) -Lys-bradykinin (B1 agonist) in gingival fibroblasts pretreated with IL-1β was impaired by IL-4. Similarly, the increased binding of B1 and B2 ligands induced by IL-1β was decreased by IL-4. In calvarial bones from Stat6-deficient mice, and in fibroblasts in which STAT6 was knocked down by siRNA, the effect of IL-4 was decreased.

CONCLUSIONS AND IMPLICATIONS

These data show, for the first time, that IL-4 and IL-13 decrease kinin receptors in a STAT6-dependent mechanism, which can be one important mechanism by which these cytokines exert their anti-inflammatory effects and impair bone resorption.

Antibody-based delivery of IL4 to the neovasculature cures mice with arthritis

Antibody-cytokine fusion proteins (immunocytokines) are innovative biopharmaceutical agents, which are being considered for the therapy of cancer and chronic inflammatory conditions. Immunomodulatory fusion proteins capable of selective localization at the sites of rheumatoid arthritis (RA) are of particular interest, as they may increase the therapeutic index of the cytokine payload. The F8 antibody recognizes the alternatively spliced extra domain A of fibronectin, a marker of angiogenesis, which is strongly overexpressed at sites of arthritis. In this study, we investigated the targeting and therapeutic activity of the immunocytokine F8-IL4 in the mouse model of collagen-induced arthritis. Different combination regimes were tested and evaluated by the analysis of serum and tissue cytokine levels. We show that F8-IL4 selectively localizes to neovascular structures at sites of rheumatoid arthritis in the mouse, leading to high local concentrations of IL4. When used in combination with dexamethasone, F8-IL4 was able to cure mice with established collagen-induced arthritis. Response to treatment was associated with an elevation of IL13 levels and decreased IL6 plasma concentrations. A fully human version of F8-IL4 is currently being developed for clinical investigations.

Effect of interleukin-4 on orthodontic tooth movement and associated root resorption

OBJECTIVES

Interleukin-4 (IL-4) is a recognized immunomodulatory cytokine that regulates bone homeostasis. However, the influence of IL-4 on orthodontic tooth movement (OTM) and subsequent root resorption is still unknown. Therefore, the purpose of this study was to investigate the effect of IL-4 on tooth movement and its associated root resorption in a mouse model.

MATERIALS AND METHODS

The maxillary first molars of four male mice for each experimental group were subjected to mesial force by a nickel titanium coil spring for 12 days. Control mice were not given appliances and injections. Varying doses of IL-4 were injected locally, adjacent to the first molar. Two sets of experiments were designed. The first set was composed of three groups: the control, treatment with phosphate-buffered saline (PBS), or 1.5 µg/day of IL-4. The second set was composed of five groups: the control, treatment with 0 (PBS only), 0.015, 0.15, or 1.5 µg/day of IL-4. The distance of OTM was measured and tartrate-resistant acid phosphatase positive cells along the loaded alveolar bone and root surface were identified. The root resorption associated with OTM was evaluated by a scanning electron microscope.

RESULTS

The amount of OTM and the number of osteoclasts were significantly decreased in the IL-4-treated mice. Moreover, IL-4 significantly suppressed force-induced odontoclasts and root resorption.

CONCLUSION

IL-4 inhibits tooth movement and prevents root resorption in the mouse model. These results suggest that IL-4 could be used as a useful adjunct to regulate the extent of OTM and also to control root resorption.

Adeno-associated viral vectors show serotype specific transduction of equine joint tissue explants and cultured monolayers

Adeno-associated virus (AAV) receptors range from heparan sulfate proteoglycan to sialic acid moieties present on cell surfaces. Abundance of the glycan profiles is greatly influenced by animal species, cell type, and culture conditions. The objective of this study was to determine whether AAV serotypes' transduction efficiencies specifically in the equine monolayer culture model are an accurate representation of transduction efficiencies in tissue explants, a model more closely related to in vivo transduction. It was found that AAV 2 and 2.5 transduced cells more efficiently in explants than in monolayers. Through experiments involving assessing enzyme degradation of cell surface proteoglycans, this change could not be attributed to differences in the extra cellular matrix (ECM), but a similar change in AAV 5 transduction efficiency could be readily explained by differences in cell surface sialylated glycan. Unexpectedly it was found that in a small but diverse sample of horses evidence for serum neutralizing antibodies was only found to AAV 5. This suggests a unique relationship between this capsid and the equine host or an unresolved relationship between similar bovine AAV and the AAV 5 capsid immune response.

Increased Th17 cell frequency and poor clinical outcome in rheumatoid arthritis are associated with a genetic variant in the IL4R gene, rs1805010

OBJECTIVE

The minor allele of the IL4R gene single-nucleotide polymorphism, rs1805010, confers impaired interleukin-4 (IL-4) signaling and has been associated with an aggressive destructive course of rheumatoid arthritis (RA). IL-4 inhibits the development of Th17 cells, a cell population recently identified as being prominent in RA patients and being associated with cartilage and bone destruction. The purpose of the present study was to investigate whether rs1805010 modulates Th17 cell development and, hence, subsequent clinical outcome in RA.

METHODS

A total of 90 patients with early, active RA (mean ± SD Disease Activity Score in 28 joints 4.6 ± 1.1) and 39 control subjects (24 healthy subjects and 15 patients with osteoarthritis [OA]) were genotyped. Serum levels of IL-17 and IL-22 as well as frequencies of Th17 cells were analyzed by enzyme-linked immunosorbent assay and flow cytometry. Clinical and radiographic data were collected and evaluated at baseline and 1 year after disease onset.

RESULTS

Twenty-six percent of the RA patients were homozygous for the major allele of rs1805010, 60% were heterozygous, and 14% were homozygous for the minor allele. The RA patients who were homozygous for the minor allele demonstrated significantly higher clinical activity associated with the presence of erosions after 1 year of followup as compared to the other RA patients. The inhibitory effect of IL-4 on Th17 cell development in these patients was significantly less prominent. Accordingly, the frequencies of Th17 cells and serum levels of IL-17 and IL-22 were significantly increased.

CONCLUSION

The data indicate that the rs1805010 minor allele contributes to increased Th17 cell frequency, enhanced clinical activity, and accelerated radiographic progression in RA by rendering CD4 T cells from RA patients insensitive to the attenuating effect of IL-4 on Th17 cell development.

Attenuation of collagen induced arthritis via suppression on Th17 response by activating cholinergic anti-inflammatory pathway with nicotine

The cholinergic anti-inflammatory pathway can inhibit the inflammation of collagen induced arthritis (CIA), a mouse model of rheumatoid arthritis (RA). However, the immunologic mechanisms that provide a therapeutic effect against the auto-inflammatory disease are not yet elucidated. The present study explores the effect of cholinergic anti-inflammatory pathway on CD4+ T cell responses in CIA. Forty DBA/1 mice were divided into 4 groups: a control group, a CIA group, a vagotomy group, and a nicotine group. The degree of arthritis was measured by arthritis score and hematoxylin and eosin. ELISA was used to detect the serum concentration of IFN-γ, IL-4 and IL-17A. Flow cytometry was used to detect the cytokines and transcription factors (TFs) (the TFs of Th1, Th2, and Th17 cells are T-bet, RORγτ and GATA3 respectively) in the spleen. Immunohistochemistry was used to analyze RORγτ expression in the joint synovium. Arthritis in the nicotine group was significantly lightened compared with that in the CIA group and in the vagotomy group. Nicotine attenuated Th17 lineage by reducing IL-17A production and RORγτ expression. The expressions of IL-4 and GATA3 were increased in the same setting. However, the expressions of IFN-γ and T-bet had no difference between the nicotine and the CIA group. Nicotine may induce a shift to the Th2 lineage and improve the Th1/Th2 imbalance. Activating the cholinergic anti-inflammatory pathway with nicotine can inhibit Th17 cell responses and may improve the Th1/Th2 imbalance in CIA, providing a new justification for its application in the treatment of rheumatoid arthritis.