Comparative Expression Analyses of Pro- versus Anti-Inflammatory Mediators within Synovium of Patients with Joint Trauma, Osteoarthritis, and Rheumatoid Arthritis

Activated macrophage membrane-coated nanoparticles relieve osteoarthritis-induced synovitis and joint damage

Osteoarthritis (OA) is a common joint condition that is a leading cause of disability worldwide. There are currently no disease-modifying treatments for osteoarthritis, which is associated with multiple kinds of inflammatory cytokines produced by M1 macrophages in the synovium of the joint. Despite recent therapeutic advancements with anti-cytokine biologics, the OA therapy response rate continues to be inadequate. To treat OA, the pro-inflammatory and anti-inflammatory responses of synoviocytes and macrophages must be controlled simultaneously. Therefore, the immune regulation capabilities of an ideal nano-drug should not only minimize pro-inflammatory responses but also effectively boost anti-inflammatory responses. In this paper, an M2H@RPK nanotherapeutic system was developed, KAFAK and shRNA-LEPR were condensed with polyethylenimine (PEI) to form a complex, which was then modified with hyaluronic acid (HA) to negatively charge to cover the M2 membrane. It was discovered that the repolarization of macrophages from the M1 to the M2 phenotype lowered pro-inflammatory responses while enhancing anti-inflammatory responses in macrophages and synoviocytes. In vitro and in vivo studies demonstrate that M2H@RPK dramatically decreases proinflammatory cytokines, controls synovial inflammation, and provides significant therapeutic efficacy by reducing joint damage. Overall, it has been demonstrated that M2H@RPK provides inflammation-targeted therapy by macrophage repolarization, and it represents a promising OA therapeutic strategy.

Identification of glucocorticoid receptors as potential modulators of parasympathetic and sympathetic neurons within rat intracardiac ganglia

Background

Emerging evidences indicate that glucocorticoid receptors (GR) play a regulatory role in cardiac function, particularly with regard to the autonomic nervous system. Therefore, this study aimed to demonstrate the expression and the precise anatomical location of GR in relation to the parasympathetic and sympathetic innervations of the heart.

Methods

The present study used tissue samples from rat heart atria to perform conventional reverse-transcriptase polymerase chain reaction (RT-PCR), Western blot, and double immunofluorescence confocal analysis of GR with the neuronal markers vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP) as well as the mineralocorticoid receptor (MR).

Results

Double immunofluorescence labeling revealed that GRs were co-expressed with VAChT in parasympathetic principal neuronal somata and nerve terminals innervating atrium. Also, GR colocalized with the sympathetic neuronal marker TH in a cluster of small intensely fluorescent (SIF) cells, on intracardiac nerve terminals and in the atrial myocardium. GR immunoreactivity was scarcely identified on CGRP-immunoreactive sensory nerve terminals. Approximately 20% of GR immunoreactive neuronal somata co-localized with MR. Finally, conventional RT-PCR and Western blot confirmed the presence of GR and MR in rat heart atria.

Conclusion

This study provides evidence for the existence of GR predominantly on cardiac parasympathetic neurons and TH-immunoreactive SIF cells suggesting a functional role of cardiac GR on cardiovascular function by modulation of the cardiac autonomic nervous system.

Minimally Invasive Embedding of Saturated MSU Induces Persistent Gouty Arthritis in Modified Rat Model

Introduction

Animal models are valid for in vivo research on the pathophysiological process and drug screening of gout arthritis. Intra-articular injection of monosodium urate (MSU) is the most common method, while stable MSU deposition enveloped by inflammatory cells was rarely reported.

Objective

To develop a modified gouty arthritis rat model characterized by intra-articular MSU deposition and continuous joint pain with a minimally invasive method.

Method

A total of twenty-four rats were randomly allocated into six groups. Three intervention groups of rats received intra-articular MSU embedment. Sham groups received pseudosurgeries with equal normal saline (NS). Gross parameters and pathological features of synovium harvested from anterior capsule were estimated. Mechanical pain threshold tests were conducted over a 96-hour period postoperatively. Moreover, quantitative immunofluorescence was conducted to assess tissue inflammation.

Result

After MSU embedding, rats got more persistent arthritic symptoms as well as tissue MSU deposition. More significant synovial swelling was detected in the MSU group compared to sham groups (P < 0.025). Behavioral tests showed that the embedding of MSU resulted in prolonged mechanical hyperalgesia during 2 hours to 96 hours postoperatively (P < 0.05). MSU depositions enveloped by inflammatory cells that express IL-1β and TNF-α were detected in embedding groups. Quantitative immunofluorescence suggested that the frequencies of MSU interventions upregulated expression of proinflammatory factors including IL-1β and TNF-α (P < 0.05).

Conclusion

A minimally invasive method was developed to establish modified rat model of intra-articular MSU deposition. This model was proved to be a simple reproducible method to mimic the pathological characteristics of persistent gouty arthritis.

The inflammatory speech of fibroblasts

Activation of fibroblasts is a key event during normal tissue repair after injury and the dysregulated repair processes that result in organ fibrosis. To most researchers, fibroblasts are rather unremarkable spindle-shaped cells embedded in the fibrous collagen matrix of connective tissues and/or deemed useful to perform mechanistic studies with adherent cells in culture. For more than a century, fibroblasts escaped thorough classification due to the lack of specific markers and were treated as the leftovers after all other cells have been identified from a tissue sample. With novel cell lineage tracing and single cell transcriptomics tools, bona fide fibroblasts emerge as only one heterogeneous sub-population of a much larger group of partly overlapping cell types, including mesenchymal stromal cells, fibro-adipogenic progenitor cells, pericytes, and/or perivascular cells. All these cells are activated to contribute to tissue repair after injury and/or chronic inflammation. "Activation" can entail various functions, such as enhanced proliferation, migration, instruction of inflammatory cells, secretion of extracellular matrix proteins and organizing enzymes, and acquisition of a contractile myofibroblast phenotype. We provide our view on the fibroblastic cell types and activation states playing a role during physiological and pathological repair and their crosstalk with inflammatory macrophages. Inflammation and fibrosis of the articular synovium during rheumatoid arthritis and osteoarthritis are used as specific examples to discuss inflammatory fibroblast phenotypes. Ultimately, delineating the precursors and functional roles of activated fibroblastic cells will contribute to better and more specific intervention strategies to treat fibroproliferative and fibrocontractive disorders.

Highly specific and label-free histological identification of microcrystals in fresh human gout tissues with stimulated Raman scattering

Gout is a common metabolic disease with growing burden, caused by monosodium urate (MSU) microcrystal deposition. In situ and chemical-specific histological identification of MSU is crucial in the diagnosis and management of gout, yet it remains inaccessible for current histological methods. Methods: Stimulated Raman scattering (SRS) microscopy was utilized to image MSU based on its fingerprint Raman spectra. We first tested SRS for the diagnosis capability of gout and the differentiation power from pseudogout with rat models of acute gout arthritis, calcium pyrophosphate deposition disease (CPDD) and comorbidity. Then, human synovial fluid and surgical specimens (n=120) were were imaged with SRS to obtain the histopathology of MSU and collagen fibers. Finally, quantitative SRS analysis was performed in gout tissue of different physiological phases (n=120) to correlate with traditional histopathology including H&E and immunohistochemistry staining. Results: We demonstrated that SRS is capable of early diagnosis of gout, rapid detection of MSU in synovial fluid and fresh unprocessed surgical tissues, and accurate differentiation of gout from pseudogout in various pathophysiological conditions. Furthermore, quantitative SRS analysis revealed the optical characteristics of MSU deposition at different pathophysiological stages, which were found to matched well with corresponding immunofluorescence histochemistry features. Conclusion: Our work demonstrated the potential of SRS microscopy for rapid intraoperative diagnosis of gout and may facilitate future fundamental researches of MSU-based diseases.

Prostanoid Receptor Subtypes and Its Endogenous Ligands with Processing Enzymes within Various Types of Inflammatory Joint Diseases

A complex inflammatory process mediated by proinflammatory cytokines and prostaglandins commonly occurs in the synovial tissue of patients with joint trauma (JT), osteoarthritis (OA), and rheumatoid arthritis (RA). This study systematically investigated the distinct expression profile of prostaglandin E2 (PGE2), its processing enzymes (COX-2), and microsomal PGES-1 (mPGES-1) as well as the corresponding prostanoid receptor subtypes (EP1-4) in representative samples of synovial tissue from these patients (JT, OA, and RA). Quantitative TaqMan®-PCR and double immunofluorescence confocal microscopy of synovial tissue determined the abundance and exact immune cell types expressing these target molecules. Our results demonstrated that PGE2 and its processing enzymes COX-2 and mPGES-1 were highest in the synovial tissue of RA, followed by the synovial tissue of OA and JT patients. Corresponding prostanoid receptor, subtypes EP3 were highly expressed in the synovium of RA, followed by the synovial tissue of OA and JT patients. These proinflammatory target molecules were distinctly identified in JT patients mostly in synovial granulocytes, in OA patients predominantly in synovial macrophages and fibroblasts, whereas in RA patients mainly in synovial fibroblasts and plasma cells. Our findings show a distinct expression profile of EP receptor subtypes and PGE2 as well as the corresponding processing enzymes in human synovium that modulate the inflammatory process in JT, OA, and RA patients.

Low levels of pro-resolving lipid mediators lipoxin-A4, resolvin-D1 and resolvin-E1 in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a disease in which joint inflammation is at the forefront but the whole body is affected, and prevention of inflammation is the main treatment approach. Lipoxins (LXs) and resolvins (Rvs) are critical molecules in the resolution of inflammation. In this study, we aimed to investigate the role of LXs and Rvs in the RA pathogenesis. To this end, we measured the LXA 4, RvD 1, RvE 1 levels, and inflammatory cytokines and chemokines IL-6, IL-8, IL-10, IL-17a, IL-22 and MCP-1 in patients with RA and healthy individuals. We found that the LXA4, RvD1, RvE1 levels of the active RA cases were significantly lower than in remission RA and healthy individuals, but the levels of inflammatory cytokines and chemokines were significantly higher. The decreases in LXs and Rvs were independent of disease activity, suggesting that there might be an impairment of LX and Rvs synthesis or catabolism in patients with RA.

Periplocin induces apoptosis and inhibits inflammation in rheumatoid arthritis fibroblast-like synoviocytes via nuclear factor kappa B pathway

Apoptotic resistance and excessive proliferation of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) stimulated by inflammation could lead to distal joint destruction and bone damage. Periplocin could promote apoptosis, resist proliferation, and reduce inflammation. However, the effect and mechanism toward periplocin in proliferation and inflammation of RA-FLSs remain unclear. The role of tumor necrosis factor (TNF)-α induced proliferation and expression of inflammatory cytokines in RA-FLSs was established. Our studies noted that cell viability of TNF-α-induced RA-FLSs was inhibited in periplocin treatment via dose-response, whereas cell apoptosis of RA-FLSs was triggered by dose-dependent effect of periplocin. Bcl-2 protein, one of the apoptotic regulators, was downregulated, while other regulators of apoptosis, including BAX, cleaved caspase-3, and cleaved caspase-9, were upregulated in RA-FLSs under periplocin treatment. In addition, periplocin decreased the TNF-α-induced mRNA and protein expression levels of interleukin (IL)-1β and IL-6 in RA-FLSs in a dose-dependent way. Finally, the increased levels of phospho (p)-inhibitor of kappa B (IκBα)/IκBα and p-NF (nuclear factor)-κB/nuclear factor kappa B (NF-κB) ratio of RA-FLSs stimulated by TNF-α were decreased by periplocin treatment. Taken together, periplocin treatment decreased cell viability and cytokines expression and promoted cell apoptosis of TNF-α-induced RA-FLSs through inhibition of NF-κB signaling pathway, providing a potential therapeutic approach for RA.

Protective effects of Clematichinenoside AR against inflammation and cytotoxicity induced by human tumor necrosis factor-α

Clematichinenoside AR (AR), a major active ingredient extracted from traditional Chinese herb Clematis chinensis Osbeck, has been demonstrated to possess anti-inflammatory and immune-modulatory activities in the treatment of experimental rheumatoid arthritis (RA). The therapeutic potential of AR was supposed to be closely correlated to its ability against tumor necrosis factor-α (TNF-α). Therefore, we aimed to explore the protective effects of Clematichinenoside AR against inflammation and cytotoxicity induced by human TNF-α. AR treatment significantly decreased IL-6 and IL-8 secretion, and attenuated MMP-1 production in human RA-derived fibroblast-like synoviocyte MH7A cells stimulated by recombinant human TNF-α (rhTNF-α). AR might antagonize rhTNF-α-induced responses in MH7A cells through inhibiting p38 and ERK MAPKs signal activation. In TNF-α-sensitive murine fibroblast L929 cells, AR treatment attenuated the proliferation inhibition ratio induced by rhTNF-α/ActD and antagonized rhTNF-α-induced cytotoxicity. The cellular and nuclear morphological alterations in apoptotic characteristics induced by rhTNF-α/ActD in L929 cells were observed to be attenuated by the pretreatment with AR under a phase-contrast and fluorescence microscopy, respectively. The Annexin V-FITC/PI double-staining assay was performed to confirm that AR pretreatment obviously decreased the cell death. The antagonistic effects of AR against rhTNF-α-induced cytotoxicity might be potentially attributed to the degeneration of reactive oxygen species and the increasing of mitochondrial membrane potential, along with the suppression of durative phosphorylation of c-Jun N-terminal kinase (JNK). Collectively, our results indicated that AR antagonizes the inflammatory and cytotoxic activities induced by human TNF-α effectively in vitro, which provided further evidence for a novel mechanism underlying AR for treating RA correlating with excessive TNF-α production.

Protective Effects of Garlic-Derived S-Allylmercaptocysteine on IL-1β-Stimulated Chondrocytes by Regulation of MMPs/TIMP-1 Ratio and Type II Collagen Expression via Suppression of NF-κB Pathway

Background

Garlic-derived S-allylmercaptocysteine (SAMC) has widely been used in many disease therapies. However, the potential effects and mechanism of SAMC on IL-1β-stimulated chondrocytes are unclear.

Methods

Chondrocytes were isolated, and 5 ng/mL of IL-1β was added to mimic the in vitro osteoarthritis (OA) model. SAMC (20 and 60 μM) was used for the treatment in OA model. Cell viability was assessed by MTT method. Western blotting, Quantitative RT-PCR, and ELISA were performed to evaluate the mechanisms in SAMC treated OA model.

Results

Following 48 h of IL-1β exposure, SAMC exhibited protection effect on IL-1β-injured chondrocyte viability. Type II collagen was elevated with reduced degradation products, as a consequence of altered MMPs/TIMP-1 ratio after SAMC treatment in IL-1β-treated chondrocytes. The protein and mRNA level of TNF-α in cellular supernatant and cells were downregulated in a dose-dependent manner. Besides, IκBα in cytoplasmic fraction was increased, while p65 level in nuclear fraction was decreased after SAMC treatment in OA.

Conclusions

This study showed that SAMC may play a protective role in IL-1β induced osteoarthritis (OA) model. This effect may be through inhibiting the NF-κB signaling pathway, therefore altering the MMPs/TIMP-1 ratio change which induced type II collagen destruction and decreasing inflammatory cytokine secretion such as TNF-α.