Articular adipose tissue resident macrophages in rheumatoid arthritis patients: potential contribution to local abnormalities

Inhibition of macrophage MAPK/NF-κB pathway and Th2 axis by mangiferin ameliorates MC903-induced atopic dermatitis

Available online Atopic dermatitis (AD) is a chronic, persistent inflammatory skin disease characterized by eczema-like lesions and itching. Although topical steroids have been reported for treating AD, they are associated with adverse effects. Thus, safer medications are needed for those who cannot tolerate these agents for long periods. Mangiferin (MAN) is a flavonoid widely found in many herbs, with significant anti-inflammatory and immunomodulatory activities. However, the potential modulatory effects and mechanisms of MAN in treating Th2 inflammation in AD are unknown. In the present study, we reported that MAN could reduce inflammatory cell infiltration and scratching at the lesion site by decreasing MC903-induced levels of Th2-type cytokines, Histamine, thymic stromal lymphopoietin, Leukotriene B4, and immunoglobulin E. The mechanism may be related to reductions in MAPK and NF-κB-associated protein phosphorylation by macrophages. The results suggested that MAN may be a promising therapeutic agent for AD.

Impact of Adipose-Derived Mesenchymal Stem Cells (ASCs) of Rheumatic Disease Patients on T Helper Cell Differentiation

Complex pathogenesis of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) is associated with an imbalance of various Th-cell subpopulations. Mesenchymal stem cells (MSCs) have the ability to restore this balance. However, bone marrow-derived MSCs of SLE and SSc patients exhibit many abnormalities, whereas the properties of adipose derived mesenchymal stem cells (ASCS) are much less known. Therefore, we examined the effect of ASCs obtained from SLE (SLE/ASCs) and SSc (SSc/ASCs) patients on Th subset differentiation, using cells from healthy donors (HD/ASCs) as controls. ASCs were co-cultured with activated CD4⁺ T cells or peripheral blood mononuclear cells. Expression of transcription factors defining Th1, Th2, Th17, and regulatory T cell (Tregs) subsets, i.e., T-bet, GATA3, RORc, and FoxP3, were analysed by quantitative RT-PCR, the concentrations of subset-specific cytokines were measured by ELISA, and Tregs formation by flow cytometry. Compared with HD/ASCs, SLE/ASCs and especially SSc/ASCs triggered Th differentiation which was disturbed at the transcription levels of genes encoding Th1- and Tregs-related transcription factors. However, we failed to find functional consequences of this abnormality, because all tested ASCs similarly switched differentiation from Th1 to Th2 direction with accompanying IFNγ/IL-4 ratio decrease, up-regulated Th17 formation and IL-17 secretion, and up-regulated classical Tregs generation.

Impact and Possible Mechanism(s) of Adipose Tissue-Derived Mesenchymal Stem Cells on T-Cell Proliferation in Patients With Rheumatic Disease

Objectives: Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are chronic wasting, incurable rheumatic diseases of autoimmune background, in which T cells play a critical pathogenic role. Autologous adipose tissue-derived mesenchymal stem cells (ASCs) may represent an alternative therapeutic option for SLE and SSc patients, but the biology of these cells is poorly understood. Methods: Herein, we evaluated the anti-proliferative impact of ASCs of healthy donors (HD/ASCs, 5 reference cell lines), SLE patients (n = 20), and SSc patients (n = 20) on T lymphocytes. To assess the direct and indirect pathway of ASCs action, peripheral blood mononuclear cells (PBMCs) and purified CD4+ T cells of HD were activated and co-cultured in cell-to-cell contact (C-C) and transwell (T-W) conditions with untreated or cytokine (TNF + IFNΥ, TI)-licensed ASCs, then analyzed by flow cytometry to rate the proliferation response of CD8+ and/or CD4+ T cells. The concentrations of kynurenines, prostaglandin E2 (PGE2), interleukin 10 (IL-10), and transforming growth factor β (TGFβ) were measured from culture supernatants. Specific inhibitors of these factors (1-MT, indomethacin, and cytokine-neutralizing antibody) were used to assess their contribution to anti-proliferative ASCs action. Results: All tested ASCs significantly decreased the number of proliferating CD4+ and CD8+ T cells, the number of division/proliferating cell (PI), and fold expansion (RI), and similarly upregulated kynurenines and PGE2, but not cytokine levels, in the co-cultures with both types of target cells. However, TI-treated SLE/ASCs and SSc/ASCs exerted a slightly weaker inhibitory effect on CD4+ T-cell replication than their respective HD/ASCs. All ASCs acted mainly via soluble factors. Their anti-proliferative effect was stronger, and kynurenine levels were higher in the T-W condition than the C-C condition. Blocking experiments indicated an involvement of kynurenine pathway in inhibiting the number of proliferating cells, PI, and RI values as well as PGE2 role in decreasing the number of proliferating cells. TGFβ did not contribute to ASCs anti-proliferative capabilities, while IL-10 seems to be involved in such activity of only SLE/ASCs. Conclusion: The results indicate that SLE/ASCs and SSc/ASCs retain their capability to restrain the expansion of allogeneic CD4+ and CD8+ T cells and act by similar mechanisms as ASCs of healthy donors and thus may have therapeutic value.

Increased Ratio of CD14++CD80+ Cells/CD14++CD163+ Cells in the Infrapatellar Fat Pad of End-Stage Arthropathy Patients

Objectives

This study sought to identify the ratio of M1/M2 cells in the infrapatellar fat pads (IFP) and subcutaneous fat tissues (SC) of osteoarthritis (OA) and rheumatoid arthritis (RA) patients. The clinical features of OA and RA patients treated with or without biological disease-modifying anti-rheumatic drugs (bDMARDs) were also assessed.

Methods

IFP and SC were collected from patients with OA and RA who are undergoing total knee arthroplasty (TKA). CD14-positive cells were then isolated from these samples. Flow cytometry was used to determine the number of CD14⁺⁺CD80⁺ cells and CD14⁺⁺CD163⁺ cells. The expression levels of lipid transcription factors, such as sterol regulatory element-binding protein 1 (SREBP1) and liver X receptor alpha (LXRA), and inflammatory cytokines were also evaluated.

Results

Twenty OA patients and 22 RA patients were enrolled in this study. Ten of the RA patients (45.4%) received bDAMRDs before TKA. On average, a fivefold increase in the number of CD14-positive cells and lower expression levels of SREBP1C and LXRA were observed in OA IFP relative to OA SC; however, these results were not obtained from the RA samples. The median ratio of CD14⁺⁺CD80⁺ cells/CD14⁺⁺CD163⁺ cells of OA IFP was 0.87 (0.76–1.09, interquartile range), which is higher to that of OA SC with a lower ratio (p = 0.05835).

Conclusions

The quantity and quality of CD14-positive cells differed between IFP and SC in arthropathy patients. To our knowledge, this is the first study to characterize the ratio of M1/M2 cells in the IFP and SC of end-stage OA and RA patients. The increased ratio of CD14⁺⁺CD80⁺ cells/CD14⁺⁺CD163⁺ cells in the IFP from patients with OA and RA treated with bDMARDs indicated that inflammation was localized in the IFP. As adipose tissue-derived innate immune cells were revealed as one of the targets for regulating inflammation, further analysis of these cells in the IFP may reveal new therapeutic strategies for inflammatory joint diseases.

Identification of Candidate Genes Related to Synovial Macrophages in Rheumatoid Arthritis by Bioinformatics Analysis

Objective

Rheumatoid arthritis (RA) is one of the most prevalent inflammatory arthritis worldwide. However, the genes and pathways associated with macrophages from synovial fluids in RA patients still remain unclear. This study aims to screen and verify differentially expressed genes (DEGs) related to identifying candidate genes related to synovial macrophages in rheumatoid arthritis by bioinformatics analysis.

Methods

We searched the Gene Expression Omnibus (GEO) database, and GSE97779 and GSE10500 with synovial macrophages expression profiling from multiple RA microarray dataset were selected to conduct a systematic analysis. GSE97779 included nine macrophage samples from synovial fluids of RA patients and five macrophage samples from primary human blood of HC. GSE10500 included five macrophage samples from synovial fluids of RA patients and three macrophage samples from primary human blood of HC. Functional annotation of DEGs was performed, including Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Protein–protein interaction (PPI) network of DEGs was established using the STRING database. CytoHubba was used to identify hub genes. MCODE was used to determine gene clusters in the interactive network.

Results

There were 2638 DEGs (1425 upregulated genes and 1213 downregulated ones) and 889 DEGs (438 upregulated genes and 451 downregulated ones) selected from GSE97779 and GSE10500, respectively. Venn diagrams showed that 173 genes were upregulated and 106 downregulated in both two datasets. The top 10 hub genes, including FN1, VEGFA, HGF, SERPINA1, MMP9, PPBP, CD44, FPR2, IGF1, and ITGAM, were identified using the PPI network.

Conclusion

This study provides new insights for the potential biomarkers and the relevant molecular mechanisms in RA patients. Our findings suggest that the 10 candidate genes might be used in diagnosis, prognosis, and therapy of RA in the future. However, further studies are required to confirm the expression of these genes in synovial macrophages in RA and control specimen.

Hepatocyte growth factor overexpression promotes osteoclastogenesis and exacerbates bone loss in CIA mice

Background

Hepatocyte growth factor (HGF) is a multifunctional growth factor that promotes various biological processes. However, the effect of HGF on bone metabolism in rheumatoid arthritis (RA) remains unknown. Here, we investigated the role of HGF in regulating osteoclastogenesis and bone resorption in RA.

Methods

The expression of HGF in RA patients and collagen-induced arthritis (CIA) mice was examined. The role of HGF on osteoclastogenesis was analysed by osteoclastogenesis and bone resorption assays. The effect of HGF inhibition was evaluated in a CIA mice model. The mechanism of HGF in regulating osteoclastogenesis and bone resorption was explored by a series of in vitro studies.

Results

HGF was overexpressed in CIA and RA. HGF stimulated osteoclastogenesis in vitro. SU11274, a selective small molecule blocker of c-Met, impeded the effect of HGF on osteoclastogenesis and bone resorption. HGF regulated osteoclastogenesis by JNK and AKT-GSK-3β-NFATc1 signallings. SU11274 protected CIA mice from pathological bone loss.

Conclusions

These data strongly suggest that the highly expressed HGF in the joint tissues contributes to bone loss in RA. Inhibition of HGF/c-Met could effectively alleviate pathological bone loss and inflammatory symptoms in CIA mice. HGF/c-Met may be used as a new target for the treatment of bone loss in RA.

Heart Failure Risk Associated With Rheumatoid Arthritis-Related Chronic Inflammation

Background

Inflammation may contribute to incident heart failure (HF). Rheumatoid arthritis (RA), a prototypic inflammatory condition, may serve as a model for understanding inflammation‐related HF risk.

Methods and Results

Using the Vanderbilt University Medical Center electronic health record, we retrospectively identified 9889 patients with RA and 9889 control patients without autoimmune disease matched for age, sex, and race. Prevalent HF at entry into the electronic health record or preceding RA diagnosis was excluded. Incident HF was ascertained using International Classification of Diseases, Ninth Revision (ICD‐9), codes and medications. Over 177 566 person‐years of follow‐up, patients with RA were at 21% greater risk of HF (95% CI, 3–42%) independent of traditional cardiovascular risk factors. Among patients with RA, higher CRP (C‐reactive protein) was associated with greater HF risk (P<0.001), while the anti‐inflammatory drug methotrexate was associated with ≈25% lower HF risk (P=0.021). In a second cohort (n=115) of prospectively enrolled patients with and without RA, we performed proteomics and cardiac magnetic resonance imaging to discover circulating markers of inflammation associated with cardiac structure and function. Artemin levels were higher in patients with RA compared with controls (P=0.009), and higher artemin levels were associated with worse ventricular end‐systolic elastance and ventricular‐vascular coupling ratio (P=0.044 and P=0.031, respectively).

Conclusions

RA, a prototypic chronic inflammatory condition, is associated with increased risk of HF. Among patients with RA, higher levels of CRP were associated with greater HF risk, while methotrexate was associated with lower risk.

Different Secretory Activity of Articular and Subcutaneous Adipose Tissues from Rheumatoid Arthritis and Osteoarthritis Patients

Rheumatoid arthritis (RA) and osteoarthritis (OA) are characterized by joint and systemic high- or low-grade inflammation, respectively. Adipose tissue (AT) may contribute to the pathogenesis of these diseases. To address this issue, we investigated whether basal and pro-inflammatory cytokine (IL-1β)-triggered release of adipocytokines (TNF, IL-6, IL-10, IL-1Ra, TGFβ, CCL2/MCP-1, CCL5/RANTES, MMP-3) from subcutaneous (ScAT) and intraarticular (AAT) adipose tissues of RA and OA patients mirror differences between these diseases in an intensity of systemic and local inflammation. We found that in both diseases basal adipocytokine release was usually higher from AAT than ScAT, reflecting stronger local than systemic inflammation. However, ScAT secreted considerable amounts of pro- and anti-inflammatory factors as well. Spontaneous secretion of some adipocytokines (MMP-3 and/or TNF, CCL2/MCP-1, IL-1Ra) was higher in osteoarthritis than rheumatoid ATs and probably caused by weaker anti-inflammatory treatment of OA patients. By contrast, reactivity of ATs to IL-1β was significantly lower in OA than RA and IL-1β antagonist (IL-1Ra) could be responsible for this because we found its overproduction in OA ATs. Interestingly, higher reactivity of ScAT than AAT to IL-1β was a characteristic for OA while reactivity of rheumatoid ScAT and AAT to this stimulus was equal. We conclude that differences between OA and RA in reactivity of AAT and ScAT to pro-inflammatory stimulus mimicking in vivo condition reflect dissimilarity in an intensity of disease-specific inflammation and thus support contribution of ATs to these pathological processes. Moreover, we propose that more efficient anti-inflammatory mechanism(s) are preserved in ATs of OA than RA patients.

Hypertension: Focus on autoimmunity and oxidative stress

Understanding the causal role of the immune and inflammatory responses in hypertension has led to questions regarding the links between hypertension and autoimmunity. Immune pathology in primary hypertension mimics several autoimmune mechanisms observed in the pathogenesis of systemic lupus erythematosus, psoriasis, systemic sclerosis, rheumatoid arthritis and periodontitis. More importantly, the prevalence of hypertension in patients with these autoimmune diseases is significantly increased, when compared to control populations. Clinical and epidemiological evidence is reviewed along with possible mechanisms linking hypertension and autoimmunity. Inflammation and oxidative stress are linked in a self-perpetuating cycle that significantly contributes to the vascular dysfunction and renal damage associated with hypertension. T cell, B cell, macrophage and NK cell infiltration into these organs is essential for this pathology. Effector cytokines such as IFN-γ, TNF-α and IL-17 affect Na⁺/H⁺ exchangers in the kidney. In blood vessels, they lead to endothelial dysfunction and loss of nitric oxide bioavailability and cause vasoconstriction. Both renal and vascular effects are, in part, mediated through induction of reactive oxygen species-producing enzymes such as superoxide anion generating NADPH oxidases and dysfunction of anti-oxidant systems. These mechanisms have recently become important therapeutic targets of novel therapies focused on scavenging oxidative (isolevuglandin) modification of neo-antigenic peptides. Effects of classical immune targeted therapies focused on immunosuppression and anti-cytokine treatments are also reviewed.

The role of infiltrating immune cells in dysfunctional adipose tissue

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

Inflammatory pattern of the infrapatellar fat pad in dogs with canine cruciate ligament disease

BACKGROUND

Despite the importance of inflammation during the pathogenesis of cranial cruciate ligament disease (CCLD) in dogs and despite the latest knowledge suggesting a significant role of adipose tissue in osteoarthritis, the infrapatellar fat pad (IFP) was up to now mostly disregarded in veterinary investigations. In the present study, the inflammatory activity of the IFP, the main adipose structure within the stifle joint, was thoroughly investigated to evaluate its potential impact in the pathogenesis of this common disease of our canine companions. Samples of IFP, subcutaneous adipose tissue (ScAT) of the thigh and synovial fluid in both diseased (n = 36) and healthy control (n = 23) dogs were tested for their immune cell composition but also for interleukins (IL-1β, IL-6, IL-8, IL-10), degradative enzymes (MMP-1, MMP-3, MMP-13, TIMP-2, iNOS) and adipokines (leptin and adiponectin). Characterization of the immune cell composition was ascertained by fluorescence activated cell sorting. Gene expression and protein release of the inflammatory markers was determined by real RT-qPCR and ELISA.

RESULTS

IFPs of dogs with CCLD had a significantly increased immune cell count with T cells (CD3) as the most abundant immune cells. T cells and macrophages (CD14) were significantly increased compared to healthy controls or corresponding ScAT. In addition, IFPs of dogs with CCLD demonstrated a significant increase on gene as well as protein level of multiple inflammatory indicators (IL-1β, IL-6, MMP-1, MMP-13) compared to the other tissues. TNFα was only increased on gene expression. Adipokine analysis showed higher secretion of adiponectin and lower leptin secretion in IFP from dogs with CCLD than from controls. In the synovial fluid from dogs with CCLD concentrations of IL-1β, MMP-1, MMP-13 as well as leptin were significantly increased compared to the synovial fluid from healthy control dogs.

CONCLUSIONS

The present study indicates that the IFP is a potential contributory factor in the pathogenesis of CCLD, due to its inflammatory phenotype and the proximity within the stifle joint. To determine the extent of this possible inter-relationship, further studies need to be undertaken.

Adipose Tissue Macrophages in Rheumatoid Arthritis: Prevalence, Disease-Related Indicators, and Associations With Cardiometabolic Risk Factors

OBJECTIVE

Adipose tissue macrophages (ATMs) are a potent source of inflammatory cytokines, with profound effects on adipose tissue function, yet their potential role in rheumatoid arthritis (RA) pathobiology is largely unstudied.

METHODS

Periumbilical subcutaneous adipose tissue was obtained from 36 RA patients and 22 non-RA controls frequency matched on demographics and body mass index. Samples were stained for the macrophage marker CD68, and the average proportions of ATMs, crown-like structures (periadipocyte aggregates of 3 or more ATMs), and fibrosis were compared between groups.

RESULTS

The adjusted proportion of ATMs among all nucleated cells was 76% higher in RA than in non-RA samples (37.7 versus 21.3%, respectively; P < 0.001), and the adjusted average number of crown-like structures was more than 1.5-fold higher in the RA group than in controls (0.58 versus 0.23 crown-like structure/high-power field, respectively; P = 0.001). ATMs were significantly more abundant in early RA and in those with anti-cyclic citrullinated peptide seropositivity. Users of methotrexate, leflunomide, and tumor necrosis factor inhibitors had a significantly lower proportion of ATMs compared with nonusers. Crown-like structures were significantly higher in patients with rheumatoid factor seropositivity and in those with C-reactive protein levels ≥10 mg/liter, and significantly lower among those treated with statins. Linear ATMs were significantly associated with whole-body insulin resistance, but not with serum lipids.

CONCLUSIONS

ATMs and crown-like structures were more abundant in RA patients and were associated with systemic inflammation, autoimmunity, and whole-body insulin resistance, suggesting possible contributions to the RA disease process. Lower levels of ATMs and crown-like structures associated with specific RA treatments suggest that adipose tissue inflammation may be ameliorated by immunomodulation.

Articular and subcutaneous adipose tissues of rheumatoid arthritis patients represent equal sources of immunoregulatory mesenchymal stem cells

Adipose-derived mesenchymal stem cells (ASCs) have immunoregulatory properties, but their activity is dependent on signals provided by the local microenvironment. It is likely that highly inflammatory milieu of rheumatoid joint affects ASCs activity. To test this hypothesis, the function of rheumatoid ASCs derived from articular adipose tissue (AT-ASCs) and ASCs derived from subcutaneous adipose tissue (Sc-ASCs) has been analysed. Articular adipose tissue (infrapatellar fat pad) and subcutaneous adipose tissue (from the site of skin closure with sutures) were obtained from rheumatoid arthritis (RA) patients undergoing total knee joint replacement surgery. ASCs were isolated accordingly to the routinely applied procedure, expanded and treated or not with IFNγ and TNF (10 ng/ml). To evaluate immunomodulatory properties of AT- and Sc-ASCs, co-cultures with peripheral blood mononuclear cells (PBMCs) from healthy donors have been set. Proliferation of activated PBMCs (³H-thymidine incorporation method), secretion of IL-10 and IL-17A in co-culture supernatants (specific ELISA tests) and T regulatory FoxP3⁺ cells (Tregs) percentage have been evaluated (flow cytometry). Performed experiments demonstrated that ASCs from both sources have comparable properties. They suppress proliferation of activated PBMCs to the similar extent, induce IL-10 secretion by resting PBMCs and moderately induce generation of FoxP3⁺ Treg cells. Interestingly, both AT-ASCs and Sc-ASCs cause increase of IL-17A secretion by activated PBMCs as well as induce up-regulation of IL-6 concentration in co-culture supernatants. We demonstrated that AT-ASCs and Sc-ASCs obtained from RA patients possess similar immunomodulatory properties despite different localization and distinct cytokine milieu of tissue of origin. Our results indicate that ASCs derived from rheumatoid adipose tissues are not strongly immunosuppressive in vitro and that they may contribute to the pathogenesis of RA due to IL-17A secretion enhancement.

Distinct Secretory Activity and Clinical Impact of Subcutaneous Abdominal Adipose Tissue in Women with Rheumatoid Arthritis and Osteoarthritis

In the general population, low-grade inflammation of adipose tissue accompanies obesity and contributes to cardiovascular disease (CVD) development, but the implication of this tissue in rheumatic disease pathology is unclear. Therefore, we characterized the secretory activity of subcutaneous abdominal adipose tissue (SAAT) of females with rheumatoid arthritis (RA) and osteoarthritis (OA) and searched for its relationship with intensity of systemic inflammation, body composition and comorbidity. The secretion of classical adipokines (leptin, adiponectin), pro- and anti-inflammatory factors, i.e. interleukin (IL)-6, IL-8, IL-10, tumour necrosis factor (TNF), macrophage migration inhibitory factor (MIF) and hepatocyte growth factor (HGF), from SAAT explants was measured by specific enzyme-linked immunosorbent assays. Patients' body composition was evaluated by bioelectric impendence technique. Rheumatoid SAAT secreted more adiponectin, IL-6, IL-10, TNF and MIF but less leptin than respective osteoarthritis tissues. In RA patients, TNF secretion correlated with cachectic body composition, HGF release was linked to secondary amyloidosis and visceral fat rating was an independent risk factor for CVD. In OA, secretion of leptin and HGF positively, while adiponectin inversely, correlated with systemic inflammation markers, and the release of MIF was an independent risk factor for CVD. This study reveals differences between RA and OA patients in SAAT secretory activity and suggests its different clinical impact in these diseases, characterized by high- and low-grade systemic inflammation, respectively. In RA, SAAT may directly or via an effect on body composition contribute to amyloidosis, cachexia or CVD co-occurring, while in OA SAAT-derived adipocytokines may rather regulate intensity of systemic inflammation and redound to CVD emergence.

Metabolic Mechanism for l-Leucine-Induced Metabolome To Eliminate Streptococcus iniae

Crucial metabolites that modulate hosts' metabolome to eliminate bacterial pathogens have been documented, but the metabolic mechanisms are largely unknown. The present study explores the metabolic mechanism for l-leucine-induced metabolome to eliminate Streptococcus iniae in tilapia. GC-MS-based metabolomics was used to investigate the tilapia liver metabolic profile in the presence of exogenous l-leucine. Thirty-seven metabolites of differential abundance were determined, and 11 metabolic pathways were enriched. Pattern recognition analysis identified serine and proline as crucial metabolites, which are the two metabolites identified in survived tilapias during S. iniae infection, suggesting that the two metabolites play crucial roles in l-leucine-induced elimination of the pathogen by the host. Exogenous l-serine reduces the mortality of tilapias infected by S. iniae, providing a robust proof supporting the conclusion. Furthermore, exogenous l-serine elevates expression of genes IL-1β and IL-8 in tilapia spleen, but not TNFα, CXCR4 and Mx, suggesting that the metabolite promotes a phagocytosis role of macrophages, which is consistent with the finding that l-leucine promotes macrophages to kill both Gram-positive and Gram-negative bacterial pathogens. Therefore, the ability of phagocytosis enhanced by exogenous l-leucine is partly attributed to elevation of l-serine. These results demonstrate a metabolic mechanism by which exogenous l-leucine modulates tilapias' metabolome to enhance innate immunity and eliminate pathogens.

Secretory activity of subcutaneous abdominal adipose tissue in male patients with rheumatoid arthritis and osteoarthritis - association with clinical and laboratory data

Introduction

Adipose tissue exerts widespread effects on the metabolism and immune system, but its activity differs between the genders. In the general population low-grade adipose tissue inflammation contributes to development of diseases of affluence. Little is known about the systemic impact of peripheral fat tissue in osteoarthritis (OA) and rheumatoid arthritis (RA), characterized by chronic, low- and high-grade systemic inflammation, respectively. To clarify this we evaluated the secretory activity of subcutaneous abdominal adipose tissue (SAAT) obtained from male patients affected with RA (n = 21) and OA (n = 13), and assessed its association with body mass and composition, demographic, clinical and laboratory data.

Material and methods

Basal and interleukin (IL)-1β-triggered secretion of selected adipocytokines from SAAT explants was measured by specific enzyme-linked immunosorbent assays (ELISA). Patients’ body composition was evaluated by bioelectric impendence technique.

Results

Rheumatoid SAAT secreted more adiponectin and macrophage migration inhibitory factor (MIF) than respective osteoarthritis tissue. In both RA and OA patient groups, stimulation of SAAT explants with IL-1β (1 ng/ml/100 mg tissue) significantly up-regulated release of pro-(IL-6, IL-8, tumor necrosis factor – TNF) and anti-inflammatory (IL-10) cytokines but had no effect on the secretion of adiponectin, leptin, MIF and hepatocyte growth factor (HGF). Compared with RA, patients with OA were more obese. In RA patients SAAT-released adiponectin and TNF inversely correlated with body mass index (BMI) and visceral fat rating (FVSC). In addition, SAAT-secreted adiponectin and leptin positively correlated with DAS28 and disease duration, respectively. In the OA group tissue-released TNF positively correlated with patients’ age.

Conclusions

We conclude that in RA male patients adipocytokines originating from SAAT are of clinical importance because: (i) adiponectin and TNF may contribute to maintenance of normal body composition and mass, (ii) in addition adiponectin may play a pathogenic role. Moreover, in both RA and OA male patients secretory activity of SAAT may vary with time.

Adipose-derived mesenchymal stem cells from infrapatellar fat pad of patients with rheumatoid arthritis and osteoarthritis have comparable immunomodulatory properties

Adipose-derived mesenchymal stem cells (ASCs) possess immunosuppressive properties, but their activity is dependent on stimuli provided by local environment. It is possible that proinflammatory milieu of rheumatoid joint affects ASCs function. To verify this hypothesis, rheumatoid ASCs (RA-ASCs) and osteoarthritic ASCs (OA-ASCs) derived from infrapatellar fat pad (IPFP) of the knee joint have been compared. RA- and OA-ASCs isolated from patients were cultured in vitro. Their secretory and proliferative activity was measured. Peripheral blood mononuclear cells (PBMCs) from healthy donors were co-cultured with ASCs. Then, PBMCs proliferation was measured by (3)H-thymidine incorporation method, cytokines secretion by immunoassays, T cells activation and regulatory T cells (Tregs) percentage - by flow cytometry. RA- and OA-ASCs properties in vitro were comparable, however, some differences in secretory activity occurred. RA- and OA-ASCs inhibited PBMCs proliferation and induced interleukin 10 production but up-regulated interleukin 17 A secretion and failed to limit release of other proinflammatory mediators (tumor necrosis factor [TNF], interferon γ [IFNγ], CCL5) by PBMCs. RA- and OA-ASCs did not suppress activation markers expression on T cells and did not trigger Tregs expansion. The present study shows that IPFP-ASCs from RA and OA patients have comparable functions in vitro. Their immunosuppressive activity seems to be impaired comparing to available data.

Adiponectin Isoforms and Leptin Impact on Rheumatoid Adipose Mesenchymal Stem Cells Function

Adiponectin and leptin have recently emerged as potential risk factors in rheumatoid arthritis (RA) pathogenesis. In this study we evaluated the effects of adiponectin and leptin on immunomodulatory function of adipose mesenchymal stem cells (ASCs) derived from infrapatellar fat pad of RA patients. ASCs were stimulated with leptin, low molecular weight (LMW) and high/middle molecular weight (HMW/MMW) adiponectin isoforms. The secretory activity of ASCs and their effect on rheumatoid synovial fibroblasts (RA-FLS) and peripheral blood mononuclear cells (PBMCs) from healthy donors have been analysed. RA-ASCs secreted spontaneously TGFβ, IL-6, IL-1Ra, PGE2, IL-8, and VEGF. Secretion of all these factors was considerably upregulated by HMW/MMW adiponectin, but not by LMW adiponectin and leptin. Stimulation with HMW/MMW adiponectin partially abolished proproliferative effect of ASC-derived soluble factors on RA-FLS but did not affect IL-6 secretion in FLS cultures. ASCs pretreated with HMW/MMW adiponectin maintained their anti-inflammatory function towards PBMCs, which was manifested by moderate PBMCs proliferation inhibition and IL-10 secretion induction. We have proved that HMW/MMW adiponectin stimulates secretory potential of rheumatoid ASCs but does not exert strong impact on ASCs function towards RA-FLS and PBMCs.

Inflammation, adiposity, and atherogenic dyslipidemia in rheumatoid arthritis: is there a paradoxical relationship?

Dyslipidemia is highly prevalent in rheumatoid arthritis (RA) and appears to be present very early in the RA disease process, in some studies even before a diagnosis of clinical RA has been made. The association between lipid measures and the risk of cardiovascular disease (CVD) in RA appears to be paradoxical, whereby lower levels of total cholesterol (TC), low-density lipoprotein (LDL-C), and atherogenic ratios are associated with higher CVD risk. This may be due to the lipid-lowering effects of RA-related systemic inflammation. Therefore, standard CVD risk calculators have been shown to underperform in RA. Data also suggest that lipoprotein particle sizes and the apolipoprotein cargo of lipoproteins skew toward atherogenic dyslipidemia in RA and may contribute to the initiation and progression of atherosclerosis. Inflammatory burden in RA may also alter the anti-inflammatory and atheroprotective roles associated with high-density lipoprotein cholesterol (HDL-C). Adipose tissue is quantitatively increased in RA patients compared with matched non-RA controls and may be more inflamed and metabolically dysfunctional compared with an otherwise similar non-RA patient. In vitro, animal, and a handful of non-RA human, studies suggest that inflamed, metabolically dysfunctional adipose tissue contributes directly to lower HDL-C levels. In turn, lower HDL-C that has been altered functionally by inflammation may lead to expanded adipose mass and further adipose dysfunction and inflammation. In the last part of this review, we speculate how the RA disease state may recapitulate these processes.