Immunology. Arsonists in rheumatoid arthritis

Mechanism of Caulophyllum robustum Maxim against rheumatoid arthritis using LncRNA-mRNA chip analysis

BACKGROUND

Caulophyllum robustum Maxim (CRM) is a medicinal compound of the Northeast and is commonly used in China for the treatment of rheumatic pain and rheumatoid arthritis (RA). A preliminary study found that CRM has good anti-inflammatory, analgesic and immunosuppressive effects. However, the specific links and targets for its function remain unclear. Our study aimed to provide a mechanism for the action of Caulophyllum robustum Maxim extraction (CRME) against RA and to establish a method for studying disease treatment using Chinese medicine.

METHODS

The 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) method was used to detect the toxicity of CRME in L929 cells, and the concentration ranges of the blank, model, and CRME drug groups were determined. Differentially expressed long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) were identified between the three groups. Gene Ontology (GO) and pathway enrichment analyses were performed to analyze the biological functions and pathways of the differentially expressed genes. Expression of Hist1h2bj, Hist1h2ba, Zfp36, Ccl3, Cxcl2 and Egr1 in the blank, model and drug groups was detected by quantitative real-time PCR (qRT-PCR), and the role of CRME on the above factors was determined to ensure consistency with the chip data.

RESULTS

A total of 329 significantly upregulated genes and 141 downregulated genes were identified between the blank and model groups. A total of 218 significantly upregulated genes and 191 downregulated genes were identified between the CRME drug group and model group. CRME has a significant role in multiple pathways involved in the occurrence and development of RA. Additionally, Hist1h2bj, Hist1h2ba, Zfp36, Ccl3, Cxcl2, and Egr1 were observed in modules of the lncRNA-mRNA weighted co-expression network, consistent with the chip data.

CONCLUSIONS

CRME has regulatory effects on inflammatory factors, the histone family, chemokines and their ligands that are related to RA-related cytokines, the RA pathway, the TNF signaling pathway, the Toll receptor-like signaling pathway, the chemokine signaling pathways and other pathways are related to the course of RA.

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome

Platelets are essential cellular effectors of hemostasis and contribute to disease as circulating effectors of pathologic thrombosis. These are their most widely known biologic activities. Nevertheless, recent observations demonstrate that platelets have a much more intricate repertoire beyond these traditional functions and that they are specialized for contributions to vascular barrier integrity, organ repair, antimicrobial host defense, inflammation, and activities across the immune continuum. Paradoxically, on the basis of clinical investigations and animal models of disease, some of these newly discovered activities of platelets appear to contribute to tissue injury. Studies in the last decade indicate unique interactions of platelets and their precursor, the megakaryocyte, in the lung and implicate platelets as essential effectors in experimental acute lung injury and clinical acute respiratory distress syndrome. Additional discoveries derived from evolving work will be required to precisely define the contributions of platelets to complex subphenotypes of acute lung injury and to determine if these remarkable and versatile blood cells are therapeutic targets in acute respiratory distress syndrome.

Long noncoding RNAs expression profile and functional networks in rheumatoid arthritis

The modifying effects of long noncoding RNAs (lncRNAs) in rheumatoid arthritis (RA) recently have drawn much attention; however, the underlying mechanisms remain largely unknown. Herein, we aim to investigate the expression profile of lncRNAs in RA and identify promising targets for RA diagnosis and treatment. Microarray screening and real-time PCR of lncRNAs were performed by use of serum samples from 3 RA patients and 3 healthy controls. Significantly differentially expressed lncRNAs were verified in serum samples from 43 RA patients and 40 healthy controls by real-time PCR. We found that there were 73 up-regulated and 61 down-regulated lncRNAs as well as 128 up-regulated and 37 down-regulated mRNAs in serum samples of RA patients. Validation in RA clinical samples indicated 5 of these lncRNAs were significantly up-regulated including RNA143598, RNA143596, HIX0032090, IGHCgamma1, and XLOC_002730. Significant association was observed between these lncRNAs and the disease course, erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) as well as anti-cyclic citrullinated peptide (anti-CCP) antibody. Additionally, 55 of the differentially expressed mRNAs were associated with 41 lncRNAs and were involved in signaling pathways of toll like receptors (TLRs), nuclear factor-kappa B (NF-κB), and cytokine, especially the IRF3/IRF7 mediated signaling transduction. Our study firstly shows the specific profile of lncRNAs in the serum of RA patients and potential signaling pathways involved in RA pathogenesis, which may provide novel targets for the diagnosis and treatment of patients with RA.

Hypotonic stress promotes ATP release, reactive oxygen species production and cell proliferation via TRPV4 activation in rheumatoid arthritis rat synovial fibroblasts

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune-disease with complex and unclear etiology. Hypotonicity of synovial fluid is a typical characteristic of RA, which may play pivotal roles in RA pathogenesis. In this work, we studied the responses of RA synovial fibroblasts to hypotonic stress in vitro and further explored the underlying mechanisms. Data showed that hyposmotic solutions significantly triggered increases in cytosolic calcium concentration ([Ca²⁺]_c) of synoviocytes. Subsequently, it caused rapid release of ATP, as well as remarkable production of intracellular reactive oxygen species (ROS). Meanwhile, hypotonic stimulus promoted the proliferation of synovial fibroblasts. These effects were almost abolished by calcium-free buffer and significantly inhibited by gadolinium (III) chloride (a mechanosensitive Ca²⁺ channel blocker) and ruthenium red (a transient receptor potential vanilloid 4 (TRPV4) blocker). 4α-phorbol 12,13-didecanoate, a specific agonist of TRPV4, also mimicked hypotonic shock-induced responses shown above. In contrast, voltage-gated channel inhibitors verapamil and nifedipine had little influences on these responses. Furthermore, RT-PCR and western blotting evidently detected TRPV4 expression at mRNA and protein level in isolated synoviocytes. Taken together, our results indicated that hypotonic stimulus resulted in ATP release, ROS production, and cell proliferation depending on Ca²⁺ entry through activation of TRPV4 channel in synoviocytes.

Pathogenic role of platelets in rheumatoid arthritis and systemic autoimmune diseases. Perspectives and therapeutic aspects

Well-recognized for their role in vascular homoeostasis, platelets may play a major role in inflammation and immunomodulation. Substantial data are emerging on the pathogenic involvement of platelets in inflammatory arthritis and autoimmune diseases, indicating the existence of crosstalk between the coagulation and inflammation system. Upon activation, platelets release pro-inflammatory platelets microparticles, which interact with leucocytes leading to joint and systemic inflammation in rheumatoid arthritis. Platelets activation by immune complexes activate dendritic cells promoting the secretion of interferon alpha, which has a key role in the development of systemic lupus erythematous. In this review, we discuss the current data on the role of platelets in the pathophysiology of inflammatory arthritis and various autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis.

Muscle Injuries and Repair: What's New on the Horizon!

Although we recognize the many advantages of improved musculoskeletal health, we also note that our ability to sustain this health and to maintain quality of life in an aging population is currently deficient. However, global efforts have produced numerous advances in tissue engineering and regenerative medicine that will collectively serve to fill this deficiency in the near future. The purpose of this review is to highlight our current knowledge, to outline our recent advances, and to discuss the evolving paradigms in skeletal muscle injury and repair.

Platelets in Pulmonary Immune Responses and Inflammatory Lung Diseases

Platelets are essential for physiological hemostasis and are central in pathological thrombosis. These are their traditional and best known activities in health and disease. In addition, however, platelets have specializations that broaden their functional repertoire considerably. These functional capabilities, some of which are recently discovered, include the ability to sense and respond to infectious and immune signals and to act as inflammatory effector cells. Human platelets and platelets from mice and other experimental animals can link the innate and adaptive limbs of the immune system and act across the immune continuum, often also linking immune and hemostatic functions. Traditional and newly recognized facets of the biology of platelets are relevant to defensive, physiological immune responses of the lungs and to inflammatory lung diseases. The emerging view of platelets as blood cells that are much more diverse and versatile than previously thought further predicts that additional features of the biology of platelets and of megakaryocytes, the precursors of platelets, will be discovered and that some of these will also influence pulmonary immune defenses and inflammatory injury.

Low-dose aspirin as an adjuvant treatment for venous leg ulceration: study protocol for a randomized controlled trial (Aspirin4VLU)

AIM

The aim of this study was to determine the effect of low-dose aspirin on venous leg ulcer healing when used in addition to compression.

BACKGROUND

The mainstay of treatment for venous leg ulcers is compression therapy and there are few adjuvant treatments to accelerate healing.

DESIGN

Pragmatic, community-based, double-blind, randomized trial.

METHODS

Participants with venous leg ulcers will receive either 150 mg aspirin or placebo daily for up to 24 weeks. Participants will receive background treatment with compression therapy (system of choice guided by participant and/or clinical preference) delivered through district nursing services. The primary outcome will be time-to-healing. Secondary outcomes will include proportion healed at 24 weeks, change in ulcer area, change in health-related quality of life, adherence, efficacy of blinding and adverse events. The trial was funded in June 2014.

DISCUSSION

The trial commenced in March 2015 and is successfully recruiting. The trial is one of three trials that will contribute to an individual participant data meta-analysis to be undertaken at the York Trials Centre.

TRIAL REGISTRATION

Registered 5 June 2014 ClinicalTrials.gov NCT02158806. Protocol version 1·1, 14 April 2015.

Human xylosyltransferases--mediators of arthrofibrosis? New pathomechanistic insights into arthrofibrotic remodeling after knee replacement therapy

Total knee replacement (TKR) is a common therapeutic option to restore joint functionality in chronic inflammatory joint diseases. Subsequent arthrofibrotic remodeling occurs in 10%, but the underlying pathomechanisms remain unclear. We evaluated the association of xylosyltransferases (XT), fibrotic mediators catalyzing glycosaminoglycan biosynthesis, leading to arthrofibrosis as well as the feasibility of using serum XT activity as a diagnostic marker. For this purpose, synovial fibroblasts (SF) were isolated from arthrofibrotic and control synovial biopsies. Basal α-smooth muscle actin expression revealed a high fibroblast-myofibroblast transition rate in arthrofibrotic fibroblasts. Fibrotic remodeling marked by enhanced XT activity, α-SMA protein expression as well as xylosyltransferase-I, collagen type III-alpha-1 and ACTA2 mRNA expression was stronger in arthrofibrotic than in control fibroblasts treated with transforming growth factor-β1 (TGF-β1). Otherwise, no differences between serum levels of XT-I activity or common fibrosis markers (galectin-3 and growth differentiation factor-15 levels (GDF-15)) were found between 95 patients with arthrofibrosis and 132 controls after TKR. In summary, XT-I was initially investigated as a key cellular mediator of arthrofibrosis and a target for therapeutic intervention. However, the blood-synovial-barrier makes arthrofibrotic molecular changes undetectable in serum. Future studies on monitoring or preventing arthrofibrotic remodeling should therefore rely on local instead of systemic parameters.

LPS stimulation of purified human platelets is partly dependent on plasma soluble CD14 to secrete their main secreted product, soluble-CD40-Ligand

Background

Platelets are instrumental to primary haemostasis; in addition, as they are central to endothelium vascular repair, they play a role in physiological inflammation. Platelets have also been demonstrated to be key players in innate immunity and inflammation, expressing Toll-like receptors (TLRs) to sense microbial infection and initiate inflammatory responses. They are equipped to decipher distinct signals, to use alternate pathways of signalling through a complete signalosome, despite their lack of a nucleus, and to adjust the innate immune response appropriately for pathogens exhibiting different types of ‘danger’ signals. Previous work has described the two main LPS isoforms-TLR4 activation pathways in purified platelets. However, the precise mechanism of TLR4 signalling in platelets is not completely unravelled, especially how this signalling may occur since platelets do not express CD14, the TLR4 pathophysiological companion for LPS sensing. Thus, we investigated from what source the CD14 molecules required for TLR4 signalling in platelets could come.

Results

Here we show that CD14, required for optimal response to LPS stimulation, is obtained from plasma, but used with restrictive regulation. These data add to the body of evidence that platelets are closer to regulatory cells than to first line defenders. The readout of our experiments is the canonical secreted cytokine-like protein, soluble (s)CD40L, a molecule that is central in physiology and pathology and that is abundantly secreted by platelets from the alpha-granules upon stimulation.

Conclusions

We show that sCD14 from plasma contributes to LPS/TLR4 signalling in platelets to allow significant release of soluble CD40L, thereby elucidating the mechanism of LPS-induced platelet responses and providing new insights for reducing LPS toxicity in the circulation.

The platelet P2 receptors in inflammation

In addition to their well characterized and established role in haemostasis and thrombosis, platelets contribute to the pathogenesis of inflammation. Adenine nucleotides are signalling molecules that regulate the function of virtually every cell in the body, by interacting with P2 receptors. Their important role in inflammation is well established. In the last few years, the pro-inflammatory roles of adenine nucleotides interacting with their platelet P2 receptors has emerged. In particular, it was shown that the platelet P2Y12 receptor for ADP significantly contributed to the pro-inflammatory effects of cysteinyl leukotrienes (CysLT) in experimental models of asthma in mice. More importantly, it was recently shown that P2Y12 variants were associated with lung function in a large family-based asthma cohort and that the P2Y12 antagonist prasugrel tended to decrease bronchial hyper-reactivity to mannitol in patients with allergic bronchial asthma in a randomized, placebo controlled trial.

CONCLUSION

These data strongly suggest that P2Y12 may represent an important pharmacological target for the treatment of patients with allergic bronchial asthma.

Precise patterning of the SEBS surface by UV lithography to evaluate the platelet function through single platelet adhesion

The micropatterned surface which was createdviaUV lithography with a photomask, was demonstrated to control single platelet adhesion, render platelets sensitive to proteins and enable assessment of the platelet function in the presence of antiplatelet agents through single platelet adhesion.

Platelet function beyond hemostasis and thrombosis

PURPOSE OF REVIEW

The platelet paradigm that is well established in hemostasis and thrombosis can be extended to other disease states. A consideration for some major health issues, such as inflammation, cancer, infection, and neuroscience, and how platelet function impacts the pathophysiology of each clinical situation is provided.

RECENT FINDINGS

Decades of research and knowledge of platelet function exist and the same is true for inflammation and cancer. The literature is full of platelet biology overlapping into other, nonthrombotic disease states. However, major gaps exist that prevent a complete mechanistic understanding of platelet function in these other diseases. Although much of the overlap provides antidotal relationships, future studies will likely uncover novel pathophysiological pathways that are highly relevant to human diseases.

SUMMARY

Recent findings in four major disease areas, inflammation, cancer, infection, and neuroscience, are described, with current literature linking the disease to platelet function. The availability of antiplatelet therapies, such as aspirin, exists and future consideration can be given as to whether antiplatelet therapy is potentially beneficial or harmful as the mechanisms of platelet involvement are better defined.

Platelets as cellular effectors of inflammation in vascular diseases

Platelets are chief effector cells in hemostasis. In addition, they are multifaceted inflammatory cells with functions that span the continuum from innate immune responses to adaptive immunity. Activated platelets have key thromboinflammatory activities in a variety of vascular disorders and vasculopathies. Recently identified inflammatory and immune activities provide insights into the biology of these versatile blood cells that are directly relevant to human vascular diseases.

Platelets: versatile modifiers of innate and adaptive immune responses to transplants

PURPOSE OF REVIEW

Over the last decade there has been mounting experimental data demonstrating that platelets contribute to acute vascular inflammation and atherosclerosis. This review focuses on recent findings that link platelets to inflammatory responses of relevance to transplants.

RECENT FINDINGS

Although it has been known that platelets modify vascular inflammation by secretion of soluble mediators and release of microparticles, new aspects of these mechanisms are being defined. For example, platelet-derived CCL5 not only functions in homomers, but also forms more potent heteromers with platelet factor 4 (PF4; CXCL4). This heteromer formation can be inhibited with small molecules. New findings also demonstrate heterologous interactions of platelet microparticles with leukocytes that may increase their range of impact. By attaching to neutrophils, platelet microparticles appear to migrate out of blood vessels and into other compartments where they stimulate secretion of cytokines. Contact of platelets with extracellular matrix also can result in cleavage of hyaluronan into fragments that serve as an endogenous danger signal.

SUMMARY

Recent findings have expanded the range of interactions by which platelets can modify innate and adaptive immune responses to transplants.

The effect of platelet-rich plasma on the regenerative therapy of muscle derived stem cells for articular cartilage repair

OBJECTIVE

Platelet-rich plasma (PRP) is reported to promote collagen synthesis and cell proliferation as well as enhance cartilage repair. Our previous study revealed that the intracapsular injection of muscle derived stem cells (MDSCs) expressing bone morphogenetic protein 4 (BMP-4) combined with soluble Flt-1 (sFlt1) was effective for repairing articular cartilage (AC) after osteoarthritis (OA) induction. The current study was undertaken to investigate whether PRP could further enhance the therapeutic effect of MDSC therapy for the OA treatment.

METHODS

MDSCs expressing BMP-4 and sFlt1 were mixed with PRP and injected into the knees of immunodeficient rats with chemically induced OA. Histological assessments were performed 4 and 12 weeks after cell transplantation. Moreover, to elucidate the repair mechanisms, we performed in vitro assays to assess cell proliferation, adhesion, migration and mixed pellet co-culture of MDSCs and OA chondrocytes.

RESULTS

The addition of PRP to MDSCs expressing BMP-4 and sFlt1 significantly improved AC repair histologically at week 4 compared to MDSCs expressing BMP-4 and sFlt1 alone. Higher numbers of cells producing type II collagen and lower levels of chondrocyte apoptosis were observed by MDSCs expressing BMP-4 and sFlt1 and mixed with PRP. In the in vitro experiments, the addition of PRP promoted proliferation, adhesion and migration of the MDSCs. During chondrogenic pellet culture, PRP tended to increase the number of type II collagen producing cells and in contrast to the in vivo data, it increased cell apoptosis.

CONCLUSIONS

Our findings indicate that PRP can promote the therapeutic potential of MDSCs expressing BMP-4 and sFlt1 for AC repair (4 weeks post-treatment) by promoting collagen synthesis, suppressing chondrocyte apoptosis and finally by enhancing the integration of the transplanted cells in the repair process.

Alloantibody induced platelet responses in transplants: potent mediators in small packages

The early histological studies of organ allografts noted platelets attached to vascular endothelium. Platelets adhere to vessels before any morphological evidence of endothelial injury. Subsequently, in vitro and in vivo experiments have demonstrated that alloantibodies can induce exocytosis of von Willebrand factor and P-selectin from endothelial cells and attachment of platelets within minutes. Platelets also adhere to and stimulate leukocytes. These interactions are increased by complement activation. After attachment platelets degranulate, releasing preformed mediators. Some chemokines stored together in platelet granules can form heteromers with synergistic functions. Heteromers containing platelet factor 4 (PF4; CXCL4) are specific to platelets and provide insights to unique platelet functions and opportunities for therapeutic intervention.

Specific lipid mediator signatures of human phagocytes: microparticles stimulate macrophage efferocytosis and pro-resolving mediators

Phagocytes orchestrate acute inflammation and host defense. Here we carried out lipid mediator (LM) metabololipidomics profiling distinct phagocytes: neutrophils (PMN), apoptotic PMN, and macrophages. Efferocytosis increased specialized pro-resolving mediator (SPM) biosynthesis, including Resolvin D1 (RvD1), RvD2, and RvE2, which were further elevated by PMN microparticles. Apoptotic PMN gave elevated prostaglandin E(2), lipoxin B(4) and RvE2, whereas zymosan-stimulated PMN showed predominantly leukotriene B(4) and 20-OH-leukotriene B(4), as well as lipoxin marker 5,15-diHETE. Using deuterium-labeled precursors (d(8)-arachidonic acid, d(5)-eicosapentaenoic acid, and d(5)-docosahexaenoic acid), we found that apoptotic PMN and microparticles contributed to SPM biosynthesis during efferocytosis. M2 macrophages produced SPM including maresin-1 (299 ± 8 vs 45 ± 6 pg/2.5 × 10(5) cells; P < .01) and lower amounts of leukotriene B(4) and prostaglandin than M1. Apoptotic PMN uptake by both macrophage subtypes led to modulation of their LM profiles. Leukotriene B(4) was down-regulated in M2 (668 ± 81 vs 351 ± 39 pg/2.5 × 10(5) cells; P < .01), whereas SPM including lipoxin A(4) (977 ± 173 vs 675 ± 167 pg/2.5 × 10(5) cells; P < .05) were increased. Conversely, uptake of apoptotic PMN by M2 macrophages reduced (∼ 25%) overall LM. Together, these results establish LM signature profiles of human phagocytes and related subpopulations. Moreover, they provide evidence for microparticle regulation of specific endogenous LM during defined stages of the acute inflammatory process and their dynamic changes in human primary phagocytes.

Assessing protein synthesis by platelets

Platelets are anucleate cytoplasts that circulate in the bloodstream for approximately 9-11 days. Because they lack nuclei, platelets were considered incapable of protein synthesis. However, studies over the last decade have revealed that platelets use a variety of translational control pathways to synthesize proteins.A variety of protocols can be employed to assess protein synthesis by platelets. These protocols are scattered throughout the literature and, more often than not, lack critical details. In this chapter, we thoroughly outline methods used in our laboratory to assess protein synthesis by platelets.

Platelets: versatile effector cells in hemostasis, inflammation, and the immune continuum

Platelets are chief effector cells in hemostasis. In addition, however, their specializations include activities and intercellular interactions that make them key effectors in inflammation and in the continuum of innate and adaptive immunity. This review focuses on the immune features of human platelets and platelets from experimental animals and on interactions between inflammatory, immune, and hemostatic activities of these anucleate but complex and versatile cells. The experimental findings and evidence for physiologic immune functions include previously unrecognized biologic characteristics of platelets and are paralleled by new evidence for unique roles of platelets in inflammatory, immune, and thrombotic diseases.