IL-1β and TNFα promote monocyte viability through the induction of GM-CSF expression by rheumatoid arthritis synovial fibroblasts

Distinct fibroblast functions associated with fibrotic and immune-mediated inflammatory diseases and their implications for therapeutic development

Fibroblasts are ubiquitous cells that can adopt many functional states. As tissue-resident sentinels, they respond to acute damage signals and shape the earliest events in fibrotic and immune-mediated inflammatory diseases. Upon sensing an insult, fibroblasts produce chemokines and growth factors to organize and support the response. Depending on the size and composition of the resulting infiltrate, these activated fibroblasts may also begin to contract or relax thus changing local stiffness within the tissue. These early events likely contribute to the divergent clinical manifestations of fibrotic and immune-mediated inflammatory diseases. Further, distinct changes to the cellular composition and signaling dialogue in these diseases drive progressive fibroblasts specialization. In fibrotic diseases, fibroblasts support the survival, activation and differentiation of myeloid cells, granulocytes and innate lymphocytes, and produce most of the pathogenic extracellular matrix proteins. Whereas, in immune-mediated inflammatory diseases, sequential accumulation of dendritic cells, T cells and B cells programs fibroblasts to support local, destructive adaptive immune responses. Fibroblast specialization has clear implications for the development of effective induction and maintenance therapies for patients with these clinically distinct diseases.

Synovial monocytes contribute to chronic inflammation in childhood-onset arthritis via IL-6/STAT signalling and cell-cell interactions

Introduction

Monocytes are key effector cells in inflammatory processes. We and others have previously shown that synovial monocytes in childhood-onset arthritis are activated. However, very little is known about how they contribute to disease and attain their pathological features. Therefore, we set out to investigate the functional alterations of synovial monocytes in childhood-onset arthritis, how they acquire this phenotype, and whether these mechanisms could be used to tailorize treatment.

Methods

The function of synovial monocytes was analysed by assays believed to reflect key pathological events, such as T-cell activation-, efferocytosis- and cytokine production assays using flow cytometry in untreated oligoarticular juvenile idiopathic arthritis (oJIA) patients (n=33). The effect of synovial fluid on healthy monocytes was investigated through mass spectrometry and functional assays. To characterize pathways induced by synovial fluid, we utilized broad-spectrum phosphorylation assays and flow cytometry, as well as inhibitors to block specific pathways. Additional effects on monocytes were studied through co-cultures with fibroblast-like synoviocytes or migration in transwell systems.

Results

Synovial monocytes display functional alterations with inflammatory and regulatory features, e.g., increased ability to induce T-cell activation, resistance to cytokine production following activation with LPS and increased efferocytosis. In vitro, synovial fluid from patients induced the regulatory features in healthy monocytes, such as resistance to cytokine production and increased efferocytosis. IL-6/JAK/STAT signalling was identified as the main pathway induced by synovial fluid, which also was responsible for a majority of the induced features. The magnitude of synovial IL-6 driven activation in monocytes was reflected in circulating cytokine levels, reflecting two groups of low vs. high local and systemic inflammation. Remaining features, such as an increased ability to induce T-cell activation and markers of antigen presentation, could be induced by cell-cell interactions, specifically via co-culture with fibroblast-like synoviocytes.

Conclusions

Synovial monocytes in childhood-onset arthritis are functionally affected and contribute to chronic inflammation, e.g., via promoting adaptive immune responses. These data support a role of monocytes in the pathogenesis of oJIA and highlight a group of patients more likely to benefit from targeting the IL-6/JAK/STAT axis to restore synovial homeostasis.

Global trends in research of fibroblasts associated with rheumatoid diseases in the 21st century: A bibliometric analysis

Background

Rheumatoid Diseases (RDs) are a group of systemic auto-immune diseases that are characterized by chronic synovitis, and fibroblast-like synoviocytes (FLSs) play an important role in the occurrence and progression of synovitis. Our study is the first to adopt bibliometric analysis to identify the global scientific production and visualize its current distribution in the 21st century, providing insights for future research through the analysis of themes and keywords.

Methods

We obtained scientific publications from the core collection of the Web of Science (WoS) database, and the bibliometric analysis and visualization were conducted by Biblioshiny software based on R-bibliometrix.

Results

From 2000 to 2022, a total of 3,391 publications were reviewed. China is the most prolific country (n = 2601), and the USA is the most cited country (cited 7225 times). The Center of Experimental Rheumatology at University Hospital Zürich supported the maximum number of articles (n = 40). Steffen Gay published 85 records with 6263 total citations, perhaps making him the most impactful researcher. Arthritis and Rheumatism, Annals of Rheumatic Diseases, and Rheumatology are the top three journals.

Conclusion

The current study revealed that rheumatoid disease (RD)-related fibroblast studies are growing. Based on the bibliometric analysis, we summarized three important topics: activation of different subsets of fibroblasts; regulation of fibroblast function; and in vitro validation of existing discoveries. They are all valuable directions, which provide reference and guidance for researchers and clinicians engaged in the research of RDs and fibroblasts.

Combination of IL-34 and AFP improves the diagnostic value during the development of HBV related hepatocellular carcinoma

IL-34 involves in host immunity regulated carcinogenesis. Alpha-fetoprotein (AFP) is related to the development of HCC. We explored if combination of IL-34 and APF could improve the diagnostic value in HBV related hepatocellular carcinoma (HBV-HCC). Serum was obtained from HBV patients or healthy control. Liver tissue was obtained from liver biopsy in CHB, HBV related cirrhosis patients or curative resection in HBV-HCC patients. Serum IL-34 and MCSF, or intrahepatic IL-34, MCSF and CD68+ tumor associate macrophages (TAMs) were determined using ELISA or immunohistochemistry. Serum IL-34 was 1.7, 1.3 or 2.3-fold higher in HBV-HCC than that of CHB, HBV related cirrhosis or healthy control, which was inhibited following trans-hepatic arterial chemoembolization (TACE) in HBV-HCC patients. Intra-hepatic IL-34 was higher in HBV-HCC than that of the other three groups. Intra-hepatic IL-34 was associated with high HBV-DNA, HBeAg−, poor differentiation and small tumor size of HBV-HCC patients. Intra-hepatic TAMs in HBV-HCC were increased 1.7 or 1.3-fold, compared to that from CHB or HBV-cirrhosis patients. Intra-hepatic TAMs were associated with high HBV-DNA, high tumor differentiation, small tumor size, abnormal AFP and more tumor number. AFP plus serum IL-34, showed the highest AUC (0.837) with sensitivity (0.632) and highest specificity (0.931), suggesting that AFP plus IL-34 enhances the reliability for prediction of the development of HBV-HCC among CHB patients. Circulating and intra-hepatic IL-34 was upregulated gradually in HBV disease progression from CHB, cirrhosis and HCC. IL-34 may be used as a diagnostic biomarker and potential therapeutic target for the management of HBV-HCC.

Cytokines and chemokines multiplex analysis in patients with low disease activity rheumatoid arthritis

Rheumatoid arthritis is a severe chronic autoimmune disorder that results from pathological activation of immune cells and altered cytokine/chemokine network. The aim of our study was to evaluate concentrations of chosen cytokines and chemokines in blood sera and synovial fluid samples isolated from low disease activity rheumatoid arthritis (RA) patients and osteoarthritis (OA) sufferers. Blood sera and synovial fluid samples have been obtained from 24 OA and 14 RA patients. Cytokines/chemokines levels have been determined using a Milliplex^® Map 38-plex human cytokine/chemokine magnetic bead-based panel (Merck Millipore, Germany) and Luminex^® MAGPIX^® platform (Luminex USA). Low disease activity RA patients showed altered concentration of numerous cytokine/chemokine when compared to OA controls—they were characterized by, inter alia, increased: eotaxin/CCL11 (p = 0.037), GRO/CXCL1 (p = 0.037), IL-2 (p = 0.013), IL-4 (p = 0.017), IL-7 (p = 0.003), IL-8 (p = 0.0007) and GM-CSF (p = 0.037) serum levels, whilst MDC/CCL22 concentration was decreased in this group (p = 0.034). Eotaxin/CCL11 (p = 0.001), GRO/CXCL1 (p = 0.041), IL-10 (p = 0.003), GM-CSF (p = 0.01), IL-1RA (p = 0.0005) and VEGF (p = 0.01) concentrations in synovial fluid of RA females were also increased. Even with low disease activity score, RA patients exhibited increased concentrations of cytokines with pro- and anti-inflammatory activities, as well as numerous chemokines, growth factors and regulators of angiogenesis. Surprisingly, RA subjects also shown decreased concentration of CCL22 chemokine. The attempt to restore cytokine balance and tolerogenic environment is ineffective in RA sufferers even with good disease management. Distinguished factors could serve as possible indicators of disease progression even in low disease activity patients.

Effect of moxibustion on autophagy and the inflammatory response of synovial cells in rheumatoid arthritis model rat

OBJECTIVE

To investigate the effect of moxibustion on synovitis and the autophagy of synoviocytes in rheumatoid arthritis (RA).

METHODS

Forty Sprague-Dawley rats were randomly divided into a normal group, model group, moxibustion group, cigarette moxibustion group, and medicine group, with eight rats included in each group. The RA model was established by subcutaneous injection of complete Freund's adjuvant into the left posterior toe. Rats in the model group were not interfered with. In the moxibustion group, rats were treated by moxibustion, where a 1-cm diameter moxa stick was applied at the left Zusanli (ST 36) point. The distance of the moxa stick to the skin was 2 cm and moxibustion was completed for 20 min daily for 15 d total. In the cigarette moxibustion group, the moxa stick was replaced by a common cigarette. In the medicine group, rats were treated with a tripterygium glycoside suspension (8 mg/kg) once a day for 15 d total. In each group, the left hind limb toe volume was measured with a toe volume meter; the synovial cells were observed by hematoxylin and eosin staining; the interleukin (IL)-4, IL-6, IL-10, IL-1β, IL-23, IL-17, and tumor necrosis factor (TNF)-α levels in serum were measured by enzyme-linked immunosorbent assay; the erythrocyte sedimentation rate (ESR) were detected by Westergren sedimentation rate testing; the C-reactive protein (CRP) and rheumatoid factor (RF) levels in serum were detected by rate nephelometry; the expression levels of ULK1, autophagy-associated protein (Atg)3, Atg5, and Atg12 messenger RNA (mRNA) in synovium were detected by real time-quantitative polymerase chain reaction (RT-qPCR); and the protein expression levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR), LC3-II, beclin-1, phosphorylated-PI3K (p-PI3K), p-Akt, p-mTOR in synovium were detected by Western blotting.

RESULTS

Among the RA model rats, joint swelling, an inflammatory reaction, and the proliferation of synovial tissue were obvious and the signal of the PI3K/Akt/mTOR pathway was active, while autophagy was inhibited. Moxibustion at Zusanli (ST36) or intragastric administration of Tripterygium wilfordii glycosides could alleviate the inflammatory reaction of RA rats; relieve the swelling of the toes; downregulate the levels of ESR, CRF, RF; lower the levels of IL-6, IL-1β, TNF-α, and IL-17; and increase the IL-4 and IL-10. At the same time, the mRNA expression levels of ULK1, Atg3, Atg5, and Atg12 and those of LC3-Ⅱ and beclin-1 were increased, while the PI3K, Akt, mTOR, p-PI3K, p-Akt, p-mTOR were decreased. Cigarette moxibustion did not significantly reduce the swelling of the toe joint in RA rats, and was not as good as that of moxibustion or Tripterygium wilfordii polyglycosides in the effects of inflammation relief and the influences of the levels of ESR, CRF, RF. While cigarette moxibustion has a weak effect to affect the expression of corresponding molecules in autophages and the expression level of the autophagy biomaker in synovial tissue. Moxibustion and tripterygium glycosides can significantly reduce the joint swelling, relieve synovitis and synovial hyperplasia, and inhibit the PI3K/Akt/mTOR signaling pathway to increase autophagy in a manner superior to cigarette moxibustion.

CONCLUSION

Moxibustion can limit the proliferation of synoviocytes in RA rats by inhibiting the PI3K/Akt/mTOR signaling pathway, promoting autophagy, effectively reducing synovitis, and alleviating joint swelling.

Effect of moxibustion on autophagy and the inflammatory response of synovial cells in rheumatoid arthritis model rat

OBJECTIVE

To investigate the effect of moxibustion on synovitis and the autophagy of synoviocytes in rheumatoid arthritis (RA).

METHODS

Forty Sprague-Dawley rats were randomly divided into a normal group, model group, moxibustion group, cigarette moxibustion group, and medicine group, with eight rats included in each group. The RA model was established by subcutaneous injection of complete Freund's adjuvant into the left posterior toe. Rats in the model group were not interfered with. In the moxibustion group, rats were treated by moxibustion, where a 1-cm diameter moxa stick was applied at the left Zusanli (ST 36) point. The distance of the moxa stick to the skin was 2 cm and moxibustion was completed for 20 min daily for 15 d total. In the cigarette moxibustion group, the moxa stick was replaced by a common cigarette. In the medicine group, rats were treated with a tripterygium glycoside suspension (8 mg/kg) once a day for 15 d total. In each group, the left hind limb toe volume was measured with a toe volume meter; the synovial cells were observed by hematoxylin and eosin staining; the interleukin (IL)-4, IL-6, IL-10, IL-1β, IL-23, IL-17, and tumor necrosis factor (TNF)-α levels in serum were measured by enzyme-linked immunosorbent assay; the erythrocyte sedimentation rate (ESR) were detected by Westergren sedimentation rate testing; the C-reactive protein (CRP) and rheumatoid factor (RF) levels in serum were detected by rate nephelometry; the expression levels of ULK1, autophagy-associated protein (Atg)3, Atg5, and Atg12 messenger RNA (mRNA) in synovium were detected by real time-quantitative polymerase chain reaction (RT-qPCR); and the protein expression levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR), LC3-II, beclin-1, phosphorylated-PI3K (p-PI3K), p-Akt, p-mTOR in synovium were detected by Western blotting.

RESULTS

Among the RA model rats, joint swelling, an inflammatory reaction, and the proliferation of synovial tissue were obvious and the signal of the PI3K/Akt/mTOR pathway was active, while autophagy was inhibited. Moxibustion at Zusanli (ST36) or intragastric administration of Tripterygium wilfordii glycosides could alleviate the inflammatory reaction of RA rats; relieve the swelling of the toes; downregulate the levels of ESR, CRF, RF; lower the levels of IL-6, IL-1β, TNF-α, and IL-17; and increase the IL-4 and IL-10. At the same time, the mRNA expression levels of ULK1, Atg3, Atg5, and Atg12 and those of LC3-Ⅱ and beclin-1 were increased, while the PI3K, Akt, mTOR, p-PI3K, p-Akt, p-mTOR were decreased. Cigarette moxibustion did not significantly reduce the swelling of the toe joint in RA rats, and was not as good as that of moxibustion or Tripterygium wilfordii polyglycosides in the effects of inflammation relief and the influences of the levels of ESR, CRF, RF. While cigarette moxibustion has a weak effect to affect the expression of corresponding molecules in autophages and the expression level of the autophagy biomaker in synovial tissue. Moxibustion and tripterygium glycosides can significantly reduce the joint swelling, relieve synovitis and synovial hyperplasia, and inhibit the PI3K/Akt/mTOR signaling pathway to increase autophagy in a manner superior to cigarette moxibustion.

CONCLUSION

Moxibustion can limit the proliferation of synoviocytes in RA rats by inhibiting the PI3K/Akt/mTOR signaling pathway, promoting autophagy, effectively reducing synovitis, and alleviating joint swelling.

Treatment With the CSF1R Antagonist GW2580, Sensitizes Microglia to Reactive Oxygen Species

Microglia activation and proliferation are hallmarks of many neurodegenerative disorders and may contribute to disease pathogenesis. Neurons actively regulate microglia survival and function, in part by secreting the microglia mitogen interleukin (IL)-34. Both IL-34 and colony stimulating factor (CSF)-1 bind colony stimulating factor receptor (CSFR)1 expressed on microglia. Systemic treatment with central nervous system (CNS) penetrant, CSFR1 antagonists, results in microglia death in a dose dependent matter, while others, such as GW2580, suppress activation during disease states without altering viability. However, it is not known how treatment with non-penetrant CSF1R antagonists, such as GW2580, affect the normal physiology of microglia. To determine how GW2580 affects microglia function, C57BL/6J mice were orally gavaged with vehicle or GW2580 (80mg/kg/d) for 8 days. Body weights and burrowing behavior were measured throughout the experiment. The effects of GW2580 on circulating leukocyte populations, brain microglia morphology, and the transcriptome of magnetically isolated adult brain microglia were determined. Body weights, burrowing behavior, and circulating leukocytes were not affected by treatment. Analysis of Iba-1 stained brain microglia indicated that GW2580 treatment altered morphology, but not cell number. Analysis of RNA-sequencing data indicated that genes related to reactive oxygen species (ROS) regulation and survival were suppressed by treatment. Treatment of primary microglia cultures with GW2580 resulted in a dose-dependent reduction in viability only when the cells were concurrently treated with LPS, an inducer of ROS. Pre-treatment with the ROS inhibitor, YCG063, blocked treatment induced reductions in viability. Finally, GW2580 sensitized microglia to hydrogen peroxide induced cell death. Together, these data suggest that partial CSF1R antagonism may render microglia more susceptible to reactive oxygen and nitrogen species.

GM-CSF: Master regulator of the T cell-phagocyte interface during inflammation

The role of granulocyte-macrophage colony-stimulating factor (GM-CSF) was sequentially redefined during the past decades. Originally described as a hematopoietic growth factor for myelopoiesis, GM-CSF was recognized as a central mediator of inflammation bridging the innate and adaptive arms of the immune system. Phagocytes sensing GM-CSF adapt an inflammatory phenotype and facilitate pathogen clearance. However, in the context of chronic tissue inflammation, GM-CSF secreted by tissue-invading lymphocytes has detrimental effects by licensing tissue damage and hyperinflammation. Accordingly, therapeutic intervention at the T cell-phagocyte interface represents an attractive target to ameliorate disease progression and immunopathology. Although GM-CSF is largely dispensable for steady state myelopoiesis, dysregulation, as seen in chronic inflammatory diseases, may however lead to disrupted haematopoiesis and long-term effects on bone marrow output. Here, we will survey the role of GM-CSF during inflammation, discuss the extent to which GM-CSF-secreting T cells, debate their introduction as a separate T cell lineage and explore current and future clinical implications of GM-CSF in human disease settings.

Extracellular Matrix-Induced GM-CSF and Hypoxia Promote Immune Control of Mycobacterium tuberculosis in Human In Vitro Granulomas

Several in vitro cellular models have been developed with the aim to reproduce and dissect human granulomatous responses, the hallmark of tuberculosis (TB) immunopathogenesis. In that context, we compared two- (2D) versus three-dimensional (3D) granuloma models resulting from infection of human peripheral blood mononuclear cells with M. tuberculosis (Mtb) in the absence or presence of a collagen-based extracellular matrix (ECM). Granuloma formation was found to be significantly enhanced in the 2D model. This feature was associated with an earlier chemokine production and lymphocyte activation, but also a significantly increased bacterial burden. Remarkably, the reduction in Mtb burden in the 3D model correlated with an increase in GM-CSF production. GM-CSF, which is known to promote macrophage survival, was found to be inherently induced by the ECM. We observed that only 3D in vitro granulomas led to the accumulation of lipid inclusions within Mtb. Our data suggest that a hypoxic environment within the ECM could be responsible for this dormant-like Mtb phenotype. Furthermore, exposure to a TNF-α antagonist reverted Mtb dormancy, thereby mimicking the reactivation of TB observed in rheumatic patients receiving this therapy. To conclude, we showed that only in vitro granulomas generated in the presence of an ECM could recapitulate some clinically relevant features of granulomatous responses in TB. As such, this model constitutes a highly valuable tool to study the interplay between immunity and Mtb stress responses as well as to evaluate novel treatment strategies.

Repositioning TH cell polarization from single cytokines to complex help

When helper T (T_H) cell polarization was initially described three decades ago, the T_H cell universe grew dramatically. New subsets were described based on their expression of few specific cytokines. Beyond T_H1 and T_H2 cells, this led to the coining of various T_H17 and regulatory (T_reg) cell subsets as well as T_H22, T_H25, follicular helper (T_FH), T_H3, T_H5 and T_H9 cells. High-dimensional single-cell analysis revealed that a categorization of T_H cells into a single-cytokine-based nomenclature fails to capture the complexity and diversity of T_H cells. Similar to the simple nomenclature used to describe innate lymphoid cells (ILCs), we propose that T_H cell polarization should be categorized in terms of the help they provide to phagocytes (type 1), to B cells, eosinophils and mast cells (type 2) and to non-immune tissue cells, including the stroma and epithelium (type 3). Studying T_H cells based on their helper function and the cells they help, rather than phenotypic features such as individual analyzed cytokines or transcription factors, better captures T_H cell plasticity and conversion as well as the breadth of immune responses in vivo.

Emerging roles of IL-34 in neurodegenerative and neurological infectious disease

Neurological infections are often devastating in their clinical presentation. Although significant advances have made in neuroimaging techniques and molecular tools for diagnosis, as well as in anti-infective therapy, these diseases always difficult to diagnose and treat. Neuroparasitic infections and virus infections lead to neurological infections. In the nervous system, various cytokines and chemokines act as neuroinflammatory agents, neuromodulators, regulate neurodevelopment, and synaptic transmission. Among the most important cytokines, interleukins (ILs) are a large group of immunomodulatory proteins that elicit a wide variety of responses in cells and tissues. These ILs are involved in pro and anti-inflammatory effects, systemic inflammation, immune system modulation and play crucial roles in fighting cancer, infectious disease, and neurological disorders. Interleukin-34 (IL-34) identified by screening a comprehensive human protein library containing ∼3400 secreted and extracellular domain proteins in a human monocyte viability assay. Recent evidence has disclosed the crucial roles of IL-34 in the proliferation and differentiation of mononuclear phagocyte lineage cells, osteoclastogenesis, and inflammation. Additionally, IL-34 plays an important role in development, homeostasis, and disease. Dysregulation in IL-34 function can lead to various inflammatory and infectious diseases (e.g. Inflammatory bowel disease, liver fibrosis, Systemic Lupus erythematosus, rheumatoid arthritis), neurological disorders (e.g. Alzheimer disease) and neurological infectious disease (e.g. West Nile virus disease). In this review, we explore the biological role of IL-34 in addition to various impairments caused by dysregulation in IL-34 and discuss their potential links that may lead to important therapeutic and/or preventive strategies for these disorders.

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.

Atherothrombosis in Acute Coronary Syndromes-From Mechanistic Insights to Targeted Therapies

The atherothrombotic substrates for acute coronary syndromes (ACS) consist of plaque ruptures, erosions and calcified nodules, while the non-atherothrombotic etiologies, such as spontaneous coronary artery dissection, coronary artery spasm and coronary embolism are the rarer causes of ACS. The purpose of this comprehensive review is to (1) summarize the histopathologic insights into the atherothrombotic plaque subtypes in acute ACS from postmortem studies; (2) provide a brief overview of atherogenesis, while mainly focusing on the events that lead to plaque destabilization and disruption; (3) summarize mechanistic data from clinical studies that have used intravascular imaging, including high-resolution optical coherence tomography, to assess culprit plaque morphology and its underlying pathobiology, especially the newly described role of innate and adaptive immunity in ACS secondary to plaque erosion; (4) discuss the utility of intravascular imaging for effective treatment of patients presenting with ACS by percutaneous coronary intervention; and (5) discuss the opportunities that these mechanistic and imaging insights may provide for more individualized treatment of patients with ACS.

Effects of TNF-α on autophagy of rheumatoid arthritis fibroblast-like synoviocytes and regulation of the NF-κB signaling pathway

Rheumatoid arthritis (RA) is a common chronic autoimmune disease, which seriously harms human health. The hyperplastic growth of fibroblast-like synoviocytes (FLSs) plays a key role in the pathogenesis of RA. However, the pathogenesis of RA remains unclear. In this experiment, we confirmed that Tumor necrosis factor alpha (TNF-α) could activate the autophagy of RA-FLSs. 3-Methyladenine (3-MA) and Chloroquine (CQ), two types of autophagy blocker, combined with TNF-α were used to treat FLSs. The results showed that this treatment caused a reduction in the level of autophagy-related protein, significant increases in the expression of apoptosis-related protein and the apoptosis rate, and significant inhibition of the proliferation-promoting ability of TNF-α. Ammonium pyrrolidinedithiocarbamate (PDTC), a specific nuclear factor kappa-B (NF-κB) activity blocker, significantly inhibited autophagy induced by TNF-α. Collectively, these findings showed, for the first time, that TNF-α can up-regulate autophagy activity and activate the NF-κB signal pathway. Inhibition of autophagy can improve the imbalance of proliferation/apoptosis of FLSs aggravated by TNF-α to some extent, thus delaying the progression of RA. The NF-κB signal pathway may be involved in the regulation of FLSs autophagy by TNF-α.

GM-CSF: A Promising Target in Inflammation and Autoimmunity

The cytokine, granulocyte macrophage-colony stimulating factor (GM-CSF), was firstly identified as being able to induce in vitro the proliferation and differentiation of bone marrow progenitors into granulocytes and macrophages. Much preclinical data have indicated that GM-CSF has a wide range of functions across different tissues in its action on myeloid cells, and GM-CSF deletion/depletion approaches indicate its potential as an important therapeutic target in several inflammatory and autoimmune disorders, for example, rheumatoid arthritis. In this review, we discuss briefly the biology of GM-CSF, raise some current issues and questions pertaining to this biology, summarize the results from preclinical models of a range of inflammatory and autoimmune disorders and list the latest clinical trials evaluating GM-CSF blockade in such disorders.

Targeting GM-CSF in COVID-19 Pneumonia: Rationale and Strategies

COVID-19 is a clinical syndrome ranging from mild symptoms to severe pneumonia that often leads to respiratory failure, need for mechanical ventilation, and death. Most of the lung damage is driven by a surge in inflammatory cytokines [interleukin-6, interferon-γ, and granulocyte-monocyte stimulating factor (GM-CSF)]. Blunting this hyperinflammation with immunomodulation may lead to clinical improvement. GM-CSF is produced by many cells, including macrophages and T-cells. GM-CSF-derived signals are involved in differentiation of macrophages, including alveolar macrophages (AMs). In animal models of respiratory infections, the intranasal administration of GM-CSF increased the proliferation of AMs and improved outcomes. Increased levels of GM-CSF have been recently described in patients with COVID-19 compared to healthy controls. While GM-CSF might be beneficial in some circumstances as an appropriate response, in this case the inflammatory response is maladaptive by virtue of being later and disproportionate. The inhibition of GM-CSF signaling may be beneficial in improving the hyperinflammation-related lung damage in the most severe cases of COVID-19. This blockade can be achieved through antagonism of the GM-CSF receptor or the direct binding of circulating GM-CSF. Initial findings from patients with COVID-19 treated with a single intravenous dose of mavrilimumab, a monoclonal antibody binding GM-CSF receptor α, showed oxygenation improvement and shorter hospitalization. Prospective, randomized, placebo-controlled trials are ongoing. Anti-GM-CSF monoclonal antibodies, TJ003234 and gimsilumab, will be tested in clinical trials in patients with COVID-19, while lenzilumab received FDA approval for compassionate use. These trials will help inform whether blunting the inflammatory signaling provided by the GM-CSF axis in COVID-19 is beneficial.

Monocyte chemoattractant protein‑1 promotes the proliferation, migration and differentiation potential of fibroblast‑like synoviocytes via the PI3K/P38 cellular signaling pathway

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints and joint destruction. Monocyte chemoattractant protein 1 (MCP‑1) is highly expressed in the joints of patients suffering from RA. The present study aimed to evaluate the effects of MCP‑1 on the phenotype of fibroblast‑like synoviocytes (FLSs) and their differentiation potential towards vascular endothelial cells. The expression of MCP‑1 in collagen‑induced arthritis (CIA) rats was investigated by PCR, ELISA and immunohistology. Cell proliferation induced by MCP‑1 was measured using a Cell Counting Kit‑8 (CCK‑8) and 5‑Bromo‑2‑deoxyuridine ELISA assay. In addition, the effects of MCP‑1 on the migration of FLSs was examined using a Transwell assay. Activation of PI3K and P38 were investigated by western blotting following MCP‑1 treatment. The vascular endothelial cell markers, tumor necrosis factor alpha (TNF‑α) and interleukin‑1 beta (IL‑β), were also examined by western blotting. LY294002 [PI3K inhibitor, (LY)] and SB203580 [P38 inhibitor, (SB)] were used to examine the proliferative and pro‑differentiation effect of PI3K and P38. The present findings showed that the expression level of MCP‑1 in the synovium of CIA rats was significantly higher compared with controls. The present in vitro study suggested that MCP‑1 increased the FLSs cell numbers with a maximal effect at 200 ng/ml, and induced the maximal phosphorylation of PI3K at 15 min and P38 at 30 min. In addition, MCP‑1 stimulation significantly increased the migration of FLSs. Furthermore, MCP‑1‑induced the expression of vascular endothelial growth factor and CD31 in FLSs. Suppression of PI3K and P38 was found to reduce MCP‑1 induced FLSs proliferation and migration, and decreased the expression levels of angiogenesis markers increased following MCP‑1 treatment. MCP‑1 was also found to increase the expression levels of both TNF‑α and IL‑β. Therefore, MCP‑1 could promote the proliferation and migration of FLSs, and was found to increase the expression levels of various angiogenesis markers via PI3K/P38, suggesting a role for this pathway in synovium hyperplasia in RA.

Nuclear Factor kappa B (NF-κB) Targeted Self-Assembled Nanoparticles Loaded with Methotrexate for Treatment of Rheumatoid Arthritis

Background

Nanotechnology is one of the most productive approaches for specifically delivering drug payloads to the region of interest to decrease nonspecific distribution and unwanted toxicities.

Material/Methods

We prepared glycol chitosan stearate self-assembled nanoparticles loaded with methotrexate (MTX) for NF-κB targeting in treatment of rheumatoid arthritis (RA). The nanoparticles were prepared using hydrophobic modification of glycol chitosan (GC) with steric acid (SA) and was characterized using IR. The efficiency of nanoparticles after their physiochemical characterization was measured in vitro and by in vivo studies in mice.

Results

The nanoparticles thus prepared were spherical in shape, 235 nm in diameter, and had negative zeta potential. The entrapment efficiency of MTX-GC-SA was more than 70%. The in vitro higher uptake of MTX-GC-SA in murine macrophage cells (RAW 264.7) was confirmed using confocal microscopy and FACS analysis. Systemic administration of MTX-GC-SA into collagen-induced arthritis (CIA) mice resulted in high accumulation in inflamed joints. The MTX-GS-SA revealed significantly better therapeutic efficacy against CIA mice compared to free MTX.

Conclusions

These findings highlight the potential of using this MTX-GC-SA nanoparticle formulation in suppressing inflammatory arthritis for effective treatment of RA.

Pro-inflammatory mediators and neutrophils are increased in synovial fluid from heifers with acute ruminal acidosis

BACKGROUND

Acute ruminal acidosis (ARA) is a metabolic disease of cattle characterized by an aseptic synovitis. ARA is the result of an increased intake of highly fermentable carbohydrates that frequently occurs in dairy cattle subjected to high production requirements. In human joint diseases such as rheumatoid arthritis and gout, several pro-inflammatory molecules are increased in the synovial fluid, including cytokines, prostaglandin E₂ (PGE₂), metalloproteinases, and neutrophil extracellular traps (NETs). The aim of this study was to identify the presence of proinflammatory mediators and neutrophils in the synovial fluid of heifers with ARA, induced by an oligofructose overload. Five heifers were challenged with an oligofructose overload (13 g/kg BW) dissolved in water. As a control, a similar vehicle volume was used in four heifers. Synovial fluid samples were collected from the tarso-crural joint and PGE₂, IL-6, IL-1β, ATP, lactate dehydrogenase (LDH), albumin, glucose, matrix metalloproteinase-9 (MMP-9), cellular free DNA, NETs, and serpin B1 were analyzed at 0, 9, and 24 h post treatment.

RESULTS

At 9 h post oligofructose overload, an increase of IL-1β, IL-6, PGE₂, serpin B1 and LDH was detected in the joints when compared to the control group. At 24 h, the synovial fluid was yellowish, viscous, turbid, and contained abundant neutrophils. An increase of DNA-backbone-like traps, histone 3 (H₃cit), aggregated neutrophil extracellular traps (aggNETs), and serpin B1 were observed 24 h post treatment. Furthermore, albumins, LDH, ATP, MMP-9, IL-6, and IL-1β were increased after 24 h.

CONCLUSIONS

The overall results indicate that IL-1β, IL-6 and PGE₂, were the earliest proinflammatory parameters that increased in the synovial fluid of animals with ARA. Furthermore, the most sever inflammatory response in the joint was observed after 24 h and could be associated with a massive presence of neutrophils and release of aggNETs.

Dectin-2-induced CCL2 production in tissue-resident macrophages ignites cardiac arteritis

Environmental triggers, including those from pathogens, are thought to play an important role in triggering autoimmune diseases, such as vasculitis, in genetically susceptible individuals. The mechanism by which activation of the innate immune system contributes to vessel-specific autoimmunity in vasculitis is not known. Systemic administration of Candida albicans water-soluble extract (CAWS) induces vasculitis in the aortic root and coronary arteries of mice that mimics human Kawasaki disease. We found that Dectin-2 signaling in macrophages resident in the aortic root of the heart induced early CCL2 production and the initial recruitment of CCR2+ inflammatory monocytes (iMo) into the aortic root and coronary arteries. iMo differentiated into monocyte-derived dendritic cells (Mo-DC) in the vessel wall and were induced to release IL-1β in a Dectin-2-Syk-NLRP3 inflammasome dependent pathway. IL-1β then activated cardiac endothelial cells to express CXCL1 and CCL2 and adhesion molecules that induced neutrophil and further iMo recruitment and accumulation in the aortic root and coronary arteries. Our findings demonstrate that Dectin-2-mediated induction of CCL2 production by macrophages resident in the aortic root and coronary arteries initiates vascular inflammation in a model of Kawasaki disease, suggesting an important role for the innate immune system in initiating vasculitis.

Comparison of therapeutic effects of different mesenchymal stem cells on rheumatoid arthritis in mice

Background

Rheumatoid arthritis (RA) is a chronic and nonspecific autoimmune disease, which leads to joint destruction and deformity. To investigate the potential of human mesenchymal stem cells (MSCs) as a new therapeutic strategy for patients with RA, we compared the therapeutic effects of bone marrow derived MSCs (BMSCs), umbilical cord derived MSCs (UCs), and stem cells derived from human exfoliated deciduous teeth (SHED) on collagen-induced arthritis (CIA) in mice.

Methods

A total of 24 DBA/1 mice were infused with type II collagen to induce RA in the experimental model. MSC-treated mice were infused with UCs, BMSCs, and SHED, respectively. Bone erosion and joint destruction were measured by micro-computed tomographic (micro-CT) analysis and hematoxylin and eosin staining. The levels of tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) were measured by immunohistochemistry and Enzyme-Linked Immunosorbent Assay (ELISA).

Results

Systemic delivery of MSCs significantly improved the severity of the symptoms related to CIA to greater extent compared with the untreated control group. Micro-CT revealed reduced bone erosions in the metatarsophalangeal joints upon treatment with MSCs. Additionally, according to histologic evaluation, reduced synovitis and articular destruction were observed in MSC-treated groups. The levels of TNF-α and IL-1β in the serum and joints decreased with treatment by MSCs.

Conclusion

Our findings suggest that systemic infusion of UCs, BMSCs, and SHED may significantly alleviate the effects of RA. The therapeutic effect of BMSCs was greater than that of SHED, while the UCs were shown to have the best therapeutic effect on CIA mice. In conclusion, compared with BMSCs and SHED, UCs may be a more suitable source of MSCs for the treatment of patients with RA.

The Role of Monocytes and Macrophages in Autoimmune Diseases: A Comprehensive Review

Monocytes (Mo) and macrophages (Mϕ) are key components of the innate immune system and are involved in regulation of the initiation, development, and resolution of many inflammatory disorders. In addition, these cells also play important immunoregulatory and tissue-repairing roles to decrease immune reactions and promote tissue regeneration. Several lines of evidence have suggested a causal link between the presence or activation of these cells and the development of autoimmune diseases. In addition, Mo or Mϕ infiltration in diseased tissues is a hallmark of several autoimmune diseases. However, the detailed contributions of these cells, whether they actually initiate disease or perpetuate disease progression, and whether their phenotype and functional alteration are merely epiphenomena are still unclear in many autoimmune diseases. Additionally, little is known about their heterogeneous populations in different autoimmune diseases. Elucidating the relevance of Mo and Mϕ in autoimmune diseases and the associated mechanisms could lead to the identification of more effective therapeutic strategies in the future.

Directs effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on adaptive immunogenesis

Background: We studied direct effects of human granulocyte-macrophage colony stimulating factor (GM-CSF) on phenotypical characteristics and cytokine-production of non-activated and activated human monocytes/macrophages (Mc/Mphs) and T cells.Methods: Purified Mc/Mphs were activated by bacterial lipopolysaccharide (LPS, 1 μg/ml) for 24 h, while T cells were activated by particles conjugated and antibodies (Abs) against human CD2, CD3, and CD28 for 48 h.Results: GM-CSF treatment (0.01-10 ng/ml) was shown to reduce percentages of CD197 (CCR7)-positive cells in non-activated Mph cultures, without affecting significantly CD14⁺ (LPS co-receptor), CD16⁺ (FcγRIII, low-affinity Fc-receptor), CD119⁺ (interferon-gamma receptor 1), and CD124⁺ (IL4 receptor α-subunit) cells. In addition, GM-CSF reduced relative numbers of CD197⁺ cells, as well as CD14⁺, CD16⁺, and CD119⁺ cells in activated Mph cultures without affecting CD124⁺ cell distribution. GM-CSF at the highest dose of 10 ng/ml enhanced TNF-α and IL-6 (but not IL-1β and IL-10) production in activated Mc/Mphs. In activated T cell cultures, GM-CSF at 0.1-1.0 ng/ml augmented CD38⁺ cell numbers in naïve СD45RA⁺/СD197⁺ and central memory СD45RA^-/СD197⁺ cell subsets, with no effect on effector СD45RA^-/СD197^- and terminally differentiated effector СD45RA⁺/СD197^- cells. GM-CSF at a low dose (0.01 ng/ml) down-regulated INF-γ production, while at a high dosage (10.0 ng/ml) up-regulated IL-2 and IL-4 production.Conclusion: In general, the results suggest that GM-CSF is able to facilitate the implication of both Mph and T cells in the adaptive immunogenesis.

Monocytes in rheumatoid arthritis: Circulating precursors of macrophages and osteoclasts and, their heterogeneity and plasticity role in RA pathogenesis

Rheumatoid arthritis (RA) is a chronic systemic, autoimmune and inflammatory disease represented as synovitis, pannus formation, adjacent bone erosions, and joint destruction. The major cells involved in the perpetuation of RA pathogenesis are CD4⁺ T-cells (mainly Th1 cells and Th17 cells), fibroblasts like synoviocytes (FLS), macrophages and B cells. Other autoimmune cells such as dendritic cells, neutrophils, mast cells, and monocytes also contribute to RA pathogenesis. Monocytes are mainly bone marrow (BM) derived cells in the circulation. The chemokine receptors CCR2 and CX3CR1 expressed by monocytes interact with chemokine ligands CCL2 (MCP-1) and CX3CL1 (fractalkine) respectively produced by FLS and this interaction promotes their migration and recruitment into RA synovium. Activated monocytes on their surface exhibit upregulated antigenic expressions such as CD14, CD16, HLA-DR, toll-like receptors (TLRs), and adhesion molecules B1 and B2 integrins. RA monocytes interconnect with other cells in a positive loop manner in the propagation of the rheumatoid process. They skew towards mainly intermediate monocyte subsets (CD14⁺⁺ CD16⁺) which produce proinflammatory cytokines such as TNF-α, IL-1β, and IL-6. Moreover, the predominant intermediate monocytes in RA differentiate into M1-macrophages which play a major role in synovial inflammation. Demonstrations suggest monocytes with CD14⁺ and CD16^- expression (classical monocytes?) differentiate to osteoclasts which are the cells responsible for bone erosion in RA synovial joints. Th17 cells induce the production of RANKL by FLS which promotes osteoclastogenesis. Cytokines mainly TNF-α, IL-1β, and IL-6 amplify osteoclastogenesis. Hence, monocytes are the circulating precursors of macrophages and osteoclasts in RA. AIM OF THE REVIEW: To enlighten the identity of monocytes, the antigenic expression on monocyte surface and their cytokines role in RA. We also emphasize about the chemokine receptors expressed by monocytes subsets and chemotaxis of circulating monocytes into RA synovium. Additionally, we review monocytes as the circulating precursors of macrophages and osteoclasts in RA joints and their heterogeneity and plasticity role in RA.

Interleukin-34 Synovial Fluid Was Associated with Knee Osteoarthritis Severity: A Cross-Sectional Study in Knee Osteoarthritis Patients in Different Radiographic Stages

Background

Inflammation might play a crucial role in the pathogenesis of osteoarthritis (OA). Interleukin-34 (IL-34) is a well-known proinflammatory cytokine.

Objective

The objective of this study was to detect IL-34 levels in serum and synovial fluid (SF) of patients with OA and to investigate their correlation with radiographic and symptomatic severity.

Methods

One hundred and eighty-two OA patients and 69 controls were recruited. IL-34 levels were measured by enzyme-linked immunosorbent assay (ELISA). Radiographic and symptomatic severity of OA was reflected by Kellgren-Lawrence (KL) grades and Western Ontario McMaster University Osteoarthritis Index (WOMAC) scores, respectively.

Results

SF IL-34 levels were independently associated with the KL grade (B = 0.273, 95% CI: 0.150–0.395; P < 0.001). SF IL-34 levels were significantly correlated with WOMAC scores (r = 0.265, 95% CI: 0.123–0.399; P < 0.001). The correlation between SF IL-34 levels and WOMAC scores was still significant after adjusting for confounding factors (B = 0.020, 95% CI: 0.001–0.038; P = 0.035) in OA patients.

Conclusions

We found that IL-34 levels in SF were significantly associated with the radiographic and symptomatic severity of knee OA.

Immunomodulatory drug methotrexate used to treat patients with chronic inflammatory rheumatisms post-chikungunya does not impair the synovial antiviral and bone repair responses

Chikungunya virus (CHIKV) is a mosquito-transmitted RNA alphavirus causing major outbreaks of infectious chronic inflammatory rheumatisms (CIR). Recently, methotrexate (MTX), a disease modifying anti-rheumatic drug has been used successfully to treat patients suffering from rheumatoid-like arthritis post-CHIK but its immunomodulatory activity in the context of viral persistence has been a matter of concerns. We herein used a model of primary human synovial fibroblasts (HSF) and the synthetic molecule polyriboinosinic:polyribocytidylic acid (PIC) to mimic chronic infectious settings in the joints of CHIKV infected patients. The innate antiviral immune and inflammatory responses were investigated in response to MTX used at the therapeutic concentration of 1 μM. We found that MTX did not affect cellular viability as indicated by the LDH release assay. By quantitative RT-PCR, we observed that HSF responded robustly to PIC by increasing ISG15 and IFNβ mRNA levels. Furthermore, PIC upregulated the mRNA expression of two of the major pattern recognition receptors, RIG-I and MDA5 involved in the innate immune detection of viral RNA. MTX did not impact the antiviral response of PIC on ISG15, IFNβ, RIG-I and MDA5 mRNA expressions. MTX alone or combined with PIC did not affect the expression of proinflammatory CCL2 and CXCL8 chemokines. PIC strongly upregulated the mRNA and protein expression of osteoclastogenic factors (IL-6, GM-CSF but not RANKL). Critically, MTX treatment alone or combined with PIC did not affect the expression of all three tested osteoclastogenic cytokines. We found that MTX alone did not increase the capacity of CHIKV to infect and replicate in HSF. In conclusion, our study argues for a beneficial effect of MTX to treat CIR post-CHIKV given that it does not critically impact the antiviral, the proinflammatory and the bone tissue remodeling responses of synovial cells.

Chikungunya is a mosquito-borne virus (CHIKV) and has been incriminated in the development of arthralgia (pain of the joint) and arthritis particularly in elderly patients. Methotrexate (MTX) has been used widely to effectively treat these chronic rheumatic symptoms. Using a model of primary human joint fibroblasts (HSF), we investigated the capacity of the MTX immunosuppressive drug to affect the immune antiviral and inflammatory responses essential to clear the virus while allowing bone tissue repair. This study is important given that CHIKV and its RNA were shown to persist in the joint for months to years post infection and leading to injuries through ill-characterized mechanisms. The molecule PIC was used to mimic the effect of viral RNA. Interestingly, we found that MTX did not affect the expression of several proinflammatory and bone repair factors by HSF. Remarkably, MTX did not also impair the antiviral response of synovial fibroblasts. Our study revealed for the first time that MTX treatment should be considered as safe even in the context of viral persistence associated with chronic inflammation. MTX will not affect the capacity of the synovial tissue to maintain antiviral mechanism, to control inflammation and to promote bone tissue repair.

Hydrogen protects lung from hypoxia/re-oxygenation injury by reducing hydroxyl radical production and inhibiting inflammatory responses

Here we investigated whether hydrogen can protect the lung from chronic injury induced by hypoxia/re-oxygenation (H/R). We developed a mouse model in which H/R exposure triggered clinically typical lung injury, involving increased alveolar wall thickening, infiltration by neutrophils, consolidation, alveolar hemorrhage, increased levels of inflammatory factors and recruitment of M1 macrophages. All these processes were attenuated in the presence of H₂. We found that H/R-induced injury in our mouse model was associated with production of hydroxyl radicals as well as increased levels of colony-stimulating factors and circulating leukocytes. H₂ attenuated H/R-induced production of hydroxyl radicals, up-regulation of colony-stimulating factors, and recruitment of neutrophils and M1 macrophages to lung tissues. However, H₂ did not substantially affect the H/R-induced increase in erythropoietin or pulmonary artery remodeling. Our results suggest that H₂ ameliorates H/R-induced lung injury by inhibiting hydroxyl radical production and inflammation in lungs. It may also prevent colony-stimulating factors from mobilizing progenitors in response to H/R-induced injury.

Advanced Glycation End Products Enhance Murine Monocyte Proliferation in Bone Marrow and Prime Them into an Inflammatory Phenotype through MAPK Signaling

OBJECTIVE

Increased monocytes, particularly the inflammatory subset, are associated with accelerated atherosclerosis in diabetes through thus far incompletely defined mechanisms. The present study tested the hypothesis that advanced glycation end products (AGEs) promote bone marrow monocytes to proliferate and drive them into an inflammatory phenotype.

METHODS AND RESULTS

In vivo, AGEs (25 mg/kg i.p. for 7 days) increased proportions of CD115⁺ monocytes and the inflammatory subset, the CD115⁺Ly6C^high cells, in murine bone marrow (flow cytometry analysis (FCM)), and enhanced gene expression of proinflammatory cytokines (IL-1β and TNF-α) but only slightly upregulated mRNA expression of anti-inflammatory cytokine (IL-10) (real-time PCR) in monocytes. In vitro, when the monocytes were treated with different dosages of AGEs (50, 150, and 300 μg/mL), we found that proliferation (CCK8) but not apoptosis (FCM) of the monocytes was induced; the mRNA expressions of proinflammatory cytokines (IL-1β and TNF-α) and GM-CSF were upregulated in a dose-dependent manner while mRNA levels of IL-10 and M-CSF were changed much less in monocytes (real-time PCR). Furthermore, AGEs (300 μg/mL) significantly enhanced the expression of Ki67 in monocytes (immunofluorescence staining (IF)), and this dose of AGEs markedly increased secretion of GM-CSF but not that of M-CSF (ELISA). For a pathway study, the monocytes were stimulated by 300 μg/mL AGEs for different periods of time (0, 15, 30, and 120 min) and the activation of the MAPK pathway was tested (FCM); the results showed the p38 and ERK pathways were activated but not JNK signaling. Pretreatment with an inhibitor of p38 (SB203580) or ERK (U0126) attenuated AGE-induced gene expression of proinflammatory cytokines and GM-CSF (real-time PCR), as well as reversing AGE-induced Ki67 expression (IF).

CONCLUSIONS

AGEs promote bone marrow monocytes to proliferate and drive them into an inflammatory phenotype through p38 and ERK activation.

Synovial fibroblasts in 2017

Stromal cells like synovial fibroblasts gained great interest over the years, since it has become clear that they strongly influence their environment and neighbouring cells. The current review describes the role of synovial fibroblasts as cells of the innate immune system and expands on their involvement in inflammation and cartilage destruction in rheumatoid arthritis (RA). Furthermore, epigenetic changes in RA synovial fibroblasts and studies that focused on the identification of different subsets of synovial fibroblasts are discussed.

GM-CSF: From Growth Factor to Central Mediator of Tissue Inflammation

The granulocyte-macrophage colony-stimulating factor (GM-CSF) was initially classified as a hematopoietic growth factor. However, unlike its close relatives macrophage CSF (M-CSF) and granulocyte CSF (G-CSF), the majority of myeloid cells do not require GM-CSF for steady-state myelopoiesis. Instead, in inflammation, GM-CSF serves as a communication conduit between tissue-invading lymphocytes and myeloid cells. Even though lymphocytes are in all likelihood the instigators of chronic inflammatory disease, GM-CSF-activated phagocytes are well equipped to cause tissue damage. The pivotal role of GM-CSF at the T cell:myeloid cell interface might shift our attention toward studying the function of the myeloid compartment in immunopathology. Targeting specifically the crosstalk between T cells and myeloid cells through GM-CSF holds promise for the development of therapeutics to combat chronic tissue inflammation. Here, we will review some of the major discoveries of the recent past, which indicate that GM-CSF is so much more than its name suggests.

Interleukin-34 inhibits hepatitis B virus replication in vitro and in vivo

Background

The hepatitis B virus (HBV) infection could activate the immune system and induce extensive inflammatory response. As the most important inflammatory factor, interleukins are critical for anti-viral immunity. Here we investigated whether interleukin-34 (IL-34) play a role in HBV infection.

Methodology/Principal findings

In this study, we first found that both serum IL-34 and IL-34 mRNA in PBMCs in chronic HBV patients was significantly decreased compared to the healthy controls. Furthermore, both IL-34 protein and mRNA levels were declined hepatoma cells expressing HBV. In addition, the clinical parameters analysis found that serum IL-34 was significantly associated with HBV DNA (P = 0.0066), ALT (P = 0.0327), AST (P = 0.0435), TB (P = 0.0406), DB (P = 0.0368) and AFP (P = 0.0225). Correlation analysis also found that serum IL-34 negatively correlated with HBV DNA copies, ALT and AST. In vitro studies found that IL-34 treatment in HepAD38 and HepG2.2.15 cells markedly inhibited HBV DNA, total RNA, 3.5kb mRNA and HBc protein. In vivo studies further demonstrated IL-34 treatment in HBV transgenic mice exhibited greater inhibition on HBV DNA, total RNA, 3.5kb mRNA and HBc protein, suggesting the effect to IL-34 on HBV is likely due to host innate or adaptive immune response.

Conclusions/Significance

Our study identified a novel interleukin, IL-34, which has anti-viral activity in HBV replication in hepatocytes in vitro and in vivo. These data suggest a rationale for the use of IL-34 in the HBV treatment.

Rheumatoid arthritis: Recent advances on its etiology, role of cytokines and pharmacotherapy

An autoimmune disease is defined as a clinical syndrome resulted from an instigation of both T cell and B cell or individually, in the absence of any present infection or any sort of distinguishable cause. Clonal deletion of auto reactive cells remains the central canon of immunology for decades, keeping the role of T cell and B cell aside, which are actually the guards to recognize the entry of foreign body. According to NIH, 23.5 million Americans are all together affected by these diseases. They are rare, but with the exception of RA. Rheumatoid arthritis is chronic and systemic autoimmune response to the multiple joints with unknown ethology, progressive disability, systemic complications, early death and high socioeconomic costs. Its ancient disease with an old history found in North American tribes since 1500 BCE, but its etiology is yet to be explored. Current conventional and biological therapies used for RA are not fulfilling the need of the patients but give only partial responses. There is a lack of consistent and liable biomarkers of prognosis therapeutic response, and toxicity. Rheumatoid arthritis is characterized by hyperplasic synovium, production of cytokines, chemokines, autoantibodies like rheumatoid factor (RF) and anticitrullinated protein antibody (ACPA), osteoclastogensis, angiogenesis and systemic consequences like cardiovascular, pulmonary, psychological, and skeletal disorders. Cytokines, a diverse group of polypeptides, play critical role in the pathogenesis of RA. Their involvement in autoimmune diseases is a rapidly growing area of biological and clinical research. Among the proinflammatory cytokines, IL-1α/β and TNF-α trigger the intracellular molecular signalling pathway responsible for the pathogenesis of RA that leads to the activation of mesenchymal cell, recruitment of innate and adaptive immune system cells, activation of synoviocytes which in term activates various mediators including tumour necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) and interleukin-8 (IL-8), resulting in inflamed synovium, increase angiogenesis and decrease lymphangiogensis. Their current pharmacotherapy should focus on their three phases of progression i.e. prearthritis phase, transition phase and clinical phase. In this way we will be able to find a way to keep the balance between the pro and anti-inflammatory cytokines that is believe to be the dogma of pathogenesis of RA. For this we need to explore new agents, whether from synthetic or natural source to find the answers for unresolved etiology of autoimmune diseases and to provide a quality of life to the patients suffering from these diseases specifically RA.

Cardiac fibroblast cytokine profiles induced by proinflammatory or profibrotic stimuli promote monocyte recruitment and modulate macrophage M1/M2 balance in vitro

Macrophage polarization plays an essential role in cardiac remodeling after injury, evolving from an initial accumulation of proinflammatory M1 macrophages to a greater balance of anti-inflammatory M2 macrophages. Whether cardiac fibroblasts themselves influence this process remains an intriguing question. In this work, we present evidence for a role of cardiac fibroblasts (CF) as regulators of macrophage recruitment and skewing. Adult rat CF, were treated with lipopolysaccharide (LPS) or TGF-β1, to evaluate ICAM-1 and VCAM-1 expression using Western blot and proinflammatory/profibrotic cytokine secretion using LUMINEX. We performed in vitro migration and adhesion assays of rat spleen monocytes to layers of TGF-β1- or LPS-pretreated CF. Finally, TGF-β1- or LPS-pretreated CF were co-cultured with monocyte, to evaluate their effects on macrophage polarization, using flow cytometry and cytokine secretion. There was a significant increase in monocyte adhesion to LPS- or TGF-β1-stimulated CF, associated with increased CF expression of ICAM-1 and VCAM-1. siRNA silencing of either ICAM-1 or VCAM-1 inhibited monocyte adhesion to LPS-pretreated CF; however, monocyte adhesion to TGF-β1-treated CF was dependent on only VCAM-1 expression. Pretreatment of CF with LPS or TGF-β1 increased monocyte migration to CF, and this effect was completely abolished with an MCP-1 antibody blockade. LPS-treated CF secreted elevated levels of TNF-α and MCP-1, and when co-cultured with monocyte, LPS-treated CF stimulated increased macrophage M1 polarization and secretion of proinflammatory cytokines (TNF-α, IL-12 and MCP-1). On the other hand, CF stimulated with TGF-β1 produced an anti-inflammatory cytokine profile (high IL-10 and IL-5, low TNF-α). When co-cultured with monocytes, the TGF-β1 stimulated fibroblasts skewed monocyte differentiation towards M2 macrophages accompanied by increased IL-10 and decreased IL-12 levels. Taken together, our results show for the first time that CF can recruit monocytes (via MCP-1-mediated chemotaxis and adhesion to ICAM-1/VCAM-1) and induce their differentiation to M1 or M2 macrophages (through the CF cytokine profile induced by proinflammatory or profibrotic stimuli).

Metastasis-associated protein 1 (MTA1) signaling in rheumatoid synovium: Regulation of inflammatory response and cytokine-mediated production of prostaglandin E2 (PGE2)

Abnormal perpetual inflammatory response and sequential cytokine-induced prostaglandin E2 (PGE2) play important roles in the pathogenesis of rheumatoid arthritis (RA). The underlying regulatory mechanism, however, remain largely unknown. Here, we discovered that expression level of Metastasis associated protein 1 (MTA1), an important chromatin modifier that plays a critical role in transcriptional regulation by modifying DNA accessibility for cofactors, was upregulated in human rheumatoid synovial tissues. Furthermore, a knockdown of MTA1 by siRNA in the human fibroblast-like synovial cell line MH7A was found to impair the 4-hydroxynonenal (4-HNE)-induced transcriptional expression levels of certain proinflammatory cytokines including IL-1β, TNF-α and IL-6. Moreover, endogenous MTA1 was required for the cytokines-induced PGE2 synthesis by rheumatoid synoviocytes. Collectively, the coordinated existence of MTA1 inside distinct cascade loops points to its indispensable role in the modulation of the integrated cytokine network along the pathogenesis of RA. Further exploration of the functional details of this master transcriptional regulator should be an attractive strategy to identify novel therapeutic target for RA and warrants execution.

Correlation Between the Expression of MicroRNA-301a-3p and the Proportion of Th17 Cells in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation and subsequent joint destruction. Previous studies have confirmed that Th17 cells play a critical role in the pathogenesis of RA. MicroRNA (miR)-301a-3p is a regulatory factor for Th17 cells differentiation that contributes to the pathogenesis of autoimmune diseases. The purposes of this study were to identify the alteration of Th17 cells and analyze the correlation between the expression of the miR-301a-3p and the proportion of Th17 cells in RA patients. The results showed that the frequency of Th17 cells and the expression of transcription factors (RORγt and STAT3) significantly increased in the peripheral blood mononuclear cells (PBMCs) from RA patients, and the associated proinflammatory cytokines were also upregulated. We also observed that the expression of protein inhibitor of activated STAT3 (PIAS3), the main cellular inhibitor of STAT3, was attenuated in RA patients and negatively correlated with the percentage of Th17 cells in RA. Interestingly, miR-301a-3p, an inhibitor of PIAS3 expression, was overexpressed in the PBMCs from RA patients and positively correlated with the frequency of Th17 cells in patients with RA. Taken together, these data indicated that miR-301a-3p and Th17 cells were augmented in peripheral blood, which may play an important role in the process of RA.

Distinct expression of interleukin (IL)-36α, β and γ, their antagonist IL-36Ra and IL-38 in psoriasis, rheumatoid arthritis and Crohn's disease

Interleukin (IL)-36α, IL-36β and IL-36γ are expressed highly in skin and are involved in the pathogenesis of psoriasis, while the antagonists IL-36Ra or IL-38, another potential IL-36 inhibitor, limit uncontrolled inflammation. The expression and role of IL-36 cytokines in rheumatoid arthritis (RA) and Crohn's disease (CD) is currently debated. Here, we observed that during imiquimod-induced mouse skin inflammation and in human psoriasis, expression of IL-36α, γ and IL-36Ra, but not IL-36β and IL-38 mRNA, was induced and correlated with IL-1β and T helper type 17 (Th17) cytokines (IL-17A, IL-22, IL-23, CCL20). In mice with collagen-induced arthritis and in the synovium of patients with RA, IL-36α, β, γ, IL-36Ra and IL-38 were all elevated and correlated with IL-1β, CCL3, CCL4 and macrophage colony-stimulating factor (M-CSF), but not with Th17 cytokines. In the colon of mice with dextran sulphate sodium-induced colitis and in patients with CD, only IL-36α, γ and IL-38 were induced at relatively low levels and correlated with IL-1β and IL-17A. We suggest that only a minor subgroup of patients with RA (17-29%) or CD (25%) had an elevated IL-36 agonists/antagonists ratio, versus 93% of patients with psoriasis. By immunohistochemistry, IL-36 cytokines were produced by various cell types in skin, synovium and colonic mucosa such as keratinocytes, CD68⁺ macrophages, dendritic/Langerhans cells and CD79α⁺ plasma cells. In primary cultures of monocytes or inflammatory macrophages (M1), IL-36β and IL-36Ra were produced constitutively, but IL-36α, γ and IL-38 were produced after lipopolysaccharide stimulation. These distinct expression profiles may help to explain why only subgroups of RA and CD patients have a potentially elevated IL-36 agonists/antagonists ratio.

Honokiol possesses potential anti-inflammatory effects on rheumatoid arthritis and GM-CSF can be a target for its treatment

OBJECTIVE

To observe the anti-inflammatory effects of honokiol in primary cultures of peripheral blood mononuclear cells of rheumatoid arthritis patients, the pro-inflammatory cytokines and potential targets were investigated.

METHODS

The levels of GM-CSF, IL-1β, TNF-α and IL-8 were determined by ELISA assay. The genes and proteins expression were analyzed by real-time PCR and Western blotting respectively.

RESULTS

The serum IL-1β, TNF-α and GM-CSF levels were 1.76-, 2.16- and 3.57-fold increased in patients with RA as compared to those of control group. Honokiol inhibited the expression levels of IL-1β, TNF-α, GM-CSF and IL-8 in PBMCs with a dose-dependent manner. Measurements obtained from supernatants were positively correlated between TNF-α and IL-1β, moreover, similar results found TNF-α levels positively correlated with GM-CSF and IL-8 activity in the supernatants of PBMCs isolated from RA patients. Furthermore, the mRNA and protein expression of IL-1β, GM-CSF and IL-8 were up-regulated when the PBMCs exposure to TNF-α, however, honokiol treatment significantly reversed the expression of IL-1β, TNF-α and GM-CSF in response to TNF-α with a dose-dependent manner.

CONCLUSIONS

This study demonstrates that honokiol could possess potential anti-inflammatory effects and inhibits TNF-α-induced IL-1β, GM-CSF and IL-8 production in PBMCs from rheumatoid arthritis patients.