Aberrant reactive oxygen and nitrogen species generation in rheumatoid arthritis (RA): causes and consequences for immune function, cell survival, and therapeutic intervention

The shared biomarkers and immune landscape in psoriatic arthritis and rheumatoid arthritis: Findings based on bioinformatics, machine learning and single-cell analysis

OBJECTIVE

Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are the most common types of inflammatory musculoskeletal disorders that share overlapping clinical features and complications. The aim of this study was to identify shared marker genes and mechanistic similarities between PsA and RA.

METHODS

We utilized datasets from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) and perform functional enrichment analyses. To identify the marker genes, we applied two machine learning algorithms: the least absolute shrinkage and selection operator (LASSO) and the support vector machine recursive feature elimination (SVM-RFE). Subsequently, we assessed the diagnostic capacity of the identified marker genes using the receiver operating characteristic (ROC) curve and decision curve analysis (DCA). A transcription factor (TF) network was constructed using data from JASPAR, HumanTFDB, and GTRD. We then employed CIBERSORT to analyze the abundance of immune infiltrates in PsA and RA, assessing the relationship between marker genes and immune cells. Additionally, cellular subpopulations were identified by analyzing single-cell sequencing data from RA, with T cells examined for trajectory and cellular communication using Monocle and CellChat, thereby exploring their linkage to marker genes.

RESULTS

A total of seven overlapping DEGs were identified between PsA and RA. Gene enrichment analysis revealed that these genes were associated with mitochondrial respiratory chain complex IV, Toll-like receptors, and NF-κB signaling pathways. Both machine learning algorithms identified Ribosomal Protein L22-like 1 (RPL22L1) and Lymphocyte Antigen 96 (LY96) as potential diagnostic markers for PsA and RA. These markers were validated using test sets and experimental approaches. Furthermore, GSEA analysis indicated that gap junctions may play a crucial role in the pathogenesis of both conditions. The TF network suggested a potential association between marker genes and core enrichment genes related to gap junctions. The application of CIBERSORT and single-cell RNA sequencing provided a comprehensive understanding of the role of marker genes in immune cell function. Our results indicated that RPL22L1 and LY96 are involved in T cell development and are associated with T cell communication with NK cells and monocytes. Notably, high expression of both RPL22L1 and LY96 was linked to enhanced VEGF signaling in T cells.

CONCLUSION

Our study identified RPL22L1 and LY96 as key biomarkers for PsA and RA. Further investigations demonstrated that these two marker genes are closely associated with gap junction function, T cell infiltration, differentiation, and VEGF signaling. Collectively, these findings provide new insights into the diagnosis and treatment of PsA and RA.

Advances in Immunomodulatory MOFs for Biomedical Applications

Given the crucial role of immune system in the occurrence and progression of various diseases such as cancer, wound healing, bone defect, and inflammation-related diseases, immunomodulation is recognized as a potential solution for treatment of these diseases. Immunomodulation includes both immunosuppression in hyperactive immune conditions and immune activation in hypoactive conditions. For these purposes, metal-organic frameworks (MOFs) are investigated to modulate immune responses either by their own bioactivities or by delivering immunomodulatory agents due to their excellent biodegradability and high delivery capacity. This review starts with an overview of the synthesis strategies of immunomodulatory MOFs, followed by a summarization on the latest applications of immunomodulatory MOFs in cancer immunomodulatory, wound healing, inflammatory disease, and bone tissue engineering. A variety of design considerations, in order to optimize immunomodulatory properties and efficacy of MOFs, is also involved. Last, the challenges and perspectives of future research, which are expected to provide researchers with new insight into the design and application of immunomodulatory MOFs, are discussed.

Thermosensitive smart hydrogel of PEITC ameliorates the therapeutic efficacy in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune condition that accompanies chronic inflammation of joints with limited therapeutic options. Phenethyl isothiocyanate (PEITC), a bioactive phytochemical, exerts its chemopreventive, anti-oxidant, and anti-inflammatory activity via the Nrf-2 pathway. However, limited water solubility, short half-life, and instability are reasons for the low bioavailability of PEITC that hampers clinical application. From studies in healthy rats, the performance of PEITC-loaded chitosan/pluronic F-127 smart hydrogel (PH) as a thermosensitive injectable demonstrated adequate thermosensitivity (gel formation), injectability (ease of administration), biocompatibility (with prolonged contact), pharmacokinetics (sustained drug release), and biosafety (nontoxic to major organs). In the adjuvant-induced arthritis (AIA) rat model, PEITC-hydrogel (PH50) injected into the knee joint lowered RA-related symptoms significantly (paw edema and arthritis score). Further, a marked reduction in bone erosion and inflammation-specific biomarkers was observed. Finally, this study demonstrates a smart injectable hydrogel optimally loaded with PEITC which is safe, biocompatible and exhibits significant therapeutic efficacy in RA conditions.

Ultrasound-Remote Selected Activation Mitophagy for Precise Treatment of Rheumatoid Arthritis by Two-Dimensional Piezoelectric Nanosheets

Excess reactive oxygen species (ROS) produced by abnormal mitochondria is one of the critical triggers of rheumatoid arthritis (RA). Existing nanocatalytic therapies can only catalyze the breakdown of ROS but cannot address the root cause of ROS production, i.e., abnormal mitochondria. Here, we designed an ultrasound (US) piezoelectric catalytic therapy, which can induce mitophagy in a spatiotemporally controlled manner to treat RA. The prepared two-dimensional piezoelectric nanosheets (NSs) Fe/BiOCl with US catalytic activity can efficiently generate electrons under US stimulation to meet the purpose of consuming H⁺ in the outer mitochondrial membrane and disturbing the H⁺ supply in the mitochondrial matrix. This causes depolarization of the mitochondrial membrane potential (MMP), triggering the autophagy of mitochondria in regions of inflammation to eliminate the source of ROS regeneration. Analysis of cellular and RA model-related experiments showed that piezoelectric US-catalyzed therapy involving Fe/BiOCl NSs alleviated RA by inducing mitophagy. This provides an explanation of the mechanism for piezoelectric US catalytic therapy and suggests promising strategies for biomedical applications of US piezoelectric materials.

Targeting inflammation and redox perturbations by lisinopril mitigates Freund's adjuvant-induced arthritis in rats: role of JAK-2/STAT-3/RANKL axis, MMPs, and VEGF

BACKGROUND

Cardiovascular disorders are major complications of rheumatoid arthritis (RA). Hence, finding effective agents that can target RA progression and its cardiovascular consequences is demanding. The present work aimed to explore the potential of lisinopril, an angiotensin-converting enzyme inhibitor, to mitigate adjuvant's-induced arthritis with emphasis on the pro-inflammatory signals, articular degradation cues, and angiogenesis alongside JAK-2/STAT-3 and Nrf2/HO-1 pathways.

METHODS

Lisinopril (10 mg/kg/day) was administered by oral gavage for 3 weeks and the target signals were examined by biochemical assays, ELISA, histopathology, immunoblotting, and immunohistochemistry.

RESULTS

Lisinopril attenuated the progression of arthritis as proven by lowering paw edema, arthritic index, and gait scores alongside diminishing the immune-cell infiltration/aberrant histopathology in the dorsal pouch lining. These favorable actions were associated with curtailing the production of inflammatory cytokines (TNF-α, IL-6, IL-1β, and IL-17) and the pro-inflammatory angiotensin II alongside upregulating the anti-inflammatory angiotensin-(1-7) in the hind paw of arthritic rats. At the molecular level, lisinopril inhibited the upstream JAK-2/STAT-3 pathway by downregulating the protein expression of p-JAK-2/total JAK-2 and p-STAT-3/total STAT-3 ratio and the nuclear levels of NF-κBp65. Meanwhile, lisinopril curbed the downstream cartilage degradation signals matrix metalloproteinases (MMP-3 and MMP-9) and the bone erosion cue RANKL. Equally important, the protein expression of the angiogenesis signal VEGF was downregulated in the hind paw/dorsal lining. With respect to oxidative stress, lisinopril suppressed the paw lipid peroxides and boosted GSH and Nrf-2/HO-1 pathway.

CONCLUSION

Lisinopril attenuated adjuvant-induced arthritis via inhibition of inflammation, articular degradation cues, and angiogenesis.

Radicals Scavenging MOFs Enabling Targeting Delivery of siRNA for Rheumatoid Arthritis Therapy

Macrophages play essential roles in the progression of rheumatoid arthritis (RA), which are polarized into the pro-inflammatory M1 phenotype with significant oxidative stress and cytokines excretion. Herein, an active targeting nanomedicine based on metal-organic frameworks (MOFs) to re-educate the diseased macrophages for RA therapy is reported. The MOFs are prepared via coordination between tannic acid (TA) and Fe³⁺ , and anti-TNF-α siRNA is loaded via a simple sonication process, achieving high loading capacity comparable to cationic vectors. The MOFs show excellent biocompatibility, and enable rapid endo/lysosome escape of siRNA via the proton-sponge effect for effective cytokines down-regulation. Importantly, such nanomedicine displays intrinsic radicals scavenging capability to eliminate a broad spectrum of reactive oxygen and nitrogen species (RONS), which in turn repolarizes the M1 macrophages into anti-inflammatory M2 phenotypes for enhanced RA therapy in combination with siRNA. The MOFs are further modified with bovine serum albumin (BSA) to allow cascade RA joint and diseased macrophages targeted delivery. As a result, an excellent anti-RA efficacy is achieved in a collagen-induced arthritis mice model. This work provides a robust gene vector with great translational potential, and offers a vivid example of rationally designing MOF structure with multifunctionalities to synergize with its payload for enhanced disease treatment.

The Role of Reactive Oxygen Species in the Rheumatoid Arthritis-Associated Synovial Microenvironment

Rheumatoid arthritis (RA) is an inflammatory disease that begins with a loss of tolerance to modified self-antigens and immune system abnormalities, eventually leading to synovitis and bone and cartilage degradation. Reactive oxygen species (ROS) are commonly used as destructive or modifying agents of cellular components or they act as signaling molecules in the immune system. During the development of RA, a hypoxic and inflammatory situation in the synovium maintains ROS generation, which can be sustained by increased DNA damage and malfunctioning mitochondria in a feedback loop. Oxidative stress caused by abundant ROS production has also been shown to be associated with synovitis in RA. The goal of this review is to examine the functions of ROS and related molecular mechanisms in diverse cells in the synovial microenvironment of RA. The strategies relying on regulating ROS to treat RA are also reviewed.

Synthesis and evaluation of a UMI-77-based fluorescent probe for selective detecting Mcl-1 protein and imaging in living cancer cells

Development of efficient fluorescent probes for detecting the overexpressed Mcl-1 protein in living cells is imperative for the diagnosis and treatment of cancers. In this paper, a new UMI-77 based fluorescent probe (DNSH), was synthesized and characterized. DNSH bound to the hydrophobic pockets of Mcl-1 protein tightly and the binding affinity was 20-fold higher than that of previous developed Mcl-1 probe. DNSH exhibited specific fluorescence response to Mcl-1 protein rather than other proteins. In the presence of Mcl-1 protein, fluorescence emission of DNSH can be switched on. Furthermore, fluorescence colocalization experiment demonstrated that DNSH can be successfully used for imaging mitochondrial Mcl-1 protein in human prostate cancer cells without a washing process. These results showed that DNSH may find useful applications in biological research such as tracking Mcl-1 protein in living biological specimens.

Altered mitochondrial proteome and functional dynamics in patients with rheumatoid arthritis

The autoimmune inflammatory disease, Rheumatoid arthritis (RA), has known imbalances in energy metabolism and superoxide levels thus may have an etiology associated with mitochondrial dysfunction. We thus evaluated the presence of a differential mitochondrial proteome as well as other characteristics including mitochondrial mass, membrane potential (Ψm), total cellular ATP and superoxide levels. Eighteen mitochondrial proteins were down-regulated while four were up-regulated in RA patients in comparison to the healthy controls (HC). A significant decrease in mitochondrial Ψm, superoxides and cellular ATP levels was observed in RA with constant mitochondrial mass suggesting mitochondrial dysfunction responsible for functional disparity in RA.

Germline and somatic mtDNA mutation spectrum of rheumatoid arthritis patients in the Taizhou area, China

Objective

Reactive oxygen species are believed to be involved in the onset of RA, and the association between nuclear-encoded mitochondrial respiratory chain-related variants and RA has recently been revealed. However, little is known about the landscape of mitochondrial DNA (mtDNA) variants in RA.

Methods

Next-generation sequencing was conducted to profile mtDNA germline and somatic variants in 124 RA patients and 123 age- and sex-matched healthy controls in the Taizhou area, China. Fisher’s exact test, SKAT and SKAT-O were used for gene-burden tests to investigate RA-related variants of mitochondrial genes. Predictive tools were applied to evaluate the pathogenicity of mtDNA variants, and mtDNA haplogroups were assigned according to mtDNA mutations recorded in PhyloTree database. The frequency distribution of mtDNA haplogroups between the groups was compared using χ2 analysis.

Results

We identified 467 RA-unique and 341 healthy control-unique mtDNA variants, with 443 common variants. Only MT-ATP6 with a significant burden of variants was identified by Fisher’s exact test, SKAT and SKAT-O, even after Bonferroni adjustment, and the enrichment variants in MT-ATP6 was mainly driven by m.8830C>A, m.8833G>C and m.8843T>A variants. Besides, four frequently low-heteroplasmic variants including the three variants above and m.14135T>G of MT-ND5 were detected in RA only; except for m.8830C>A, they are considered potential pathogenicity based on functional predictions. χ2 analysis before Bonferroni adjustment revealed haplogroup F1/F1a to be negatively associated with RA (P < 0.05).

Conclusion

These results profiled the landscape of germline and somatic mtDNA variants in RA and supported the effects of mitochondrial genes on RA.

Hydrogen Sulfide as Potential Regulatory Gasotransmitter in Arthritic Diseases

The social and economic impact of chronic inflammatory diseases, such as arthritis, explains the growing interest of the research in this field. The antioxidant and anti-inflammatory properties of the endogenous gasotransmitter hydrogen sulfide (H₂S) were recently demonstrated in the context of different inflammatory diseases. In particular, H₂S is able to suppress the production of pro-inflammatory mediations by lymphocytes and innate immunity cells. Considering these biological effects of H₂S, a potential role in the treatment of inflammatory arthritis, such as rheumatoid arthritis (RA), can be postulated. However, despite the growing interest in H₂S, more evidence is needed to understand the pathophysiology and the potential of H₂S as a therapeutic agent. Within this review, we provide an overview on H₂S biological effects, on its role in immune-mediated inflammatory diseases, on H₂S releasing drugs, and on systems of tissue repair and regeneration that are currently under investigation for potential therapeutic applications in arthritic diseases.

Serum levels of reactive oxygen metabolites at 12 weeks during tocilizumab therapy are predictive of 52 weeks-disease activity score-remission in patients with rheumatoid arthritis

Background

To verify whether serum levels of reactive oxygen metabolites (ROM) are predictive of future clinical remission in patients with rheumatoid arthritis (RA) receiving tocilizumab (TCZ) therapy.

Methods

A total of 46 patients with RA receiving TCZ therapy were enrolled in this study. Patients were divided into remission and non-remission groups based on disease activity score 28 (DAS28)-erythrocyte sedimentation rate (ESR) or clinical disease activity index (CDAI) at 52 weeks. Associations between serum levels of ROM, C-reactive protein (CRP), and matrix metalloproteinase-3 (MMP-3) at 4 and 12 weeks and the remission by DAS28-ESR and CDAI at 52 weeks were investigated.

Results

There were no significant differences in CRP and MMP-3 between DAS- or CDAI-remission and non-remission groups at 12 weeks. However, ROM in DAS-remission group were significantly lower than those in the non-remission group. For ROM, the area under the curve of the receiver operating characteristic curve was 0.735 and the cut-off value that distinguished DAS-remission group from non-remission group was 305.5 U. Carr (sensitivity: 70.0%, specificity: 72.2%). A multivariate logistic regression analysis revealed that ROM at 12 weeks was associated with DAS-remission at 52 weeks (odds ratio: 6.067, 95% confidence interval: 1.305–28.203).

Conclusion

Serum levels of ROM at 12 weeks during TCZ therapy may be predictive of DAS-remission at 52 weeks in patients with RA.

Mitochondrial dysfunction in rheumatoid arthritis: A comprehensive analysis by integrating gene expression, protein-protein interactions and gene ontology data

Several studies have reported mitochondrial dysfunction in rheumatoid arthritis (RA). Many nuclear DNA (nDNA) encoded proteins translocate to mitochondria, but their participation in the dysfunction of this cell organelle during RA is quite unclear. In this study, we have carried out an integrative analysis of gene expression, protein-protein interactions (PPI) and gene ontology data. The analysis has identified potential implications of the nDNA encoded proteins in RA mitochondrial dysfunction. Firstly, by analysing six synovial microarray datasets of RA patients and healthy controls obtained from the gene expression omnibus (GEO) database, we found differentially expressed nDNA genes that encode mitochondrial proteins. We uncovered some of the roles of these genes in RA mitochondrial dysfunction using literature search and gene ontology analysis. Secondly, by employing gene co-expression from microarrays and collating reliable PPI from seven databases, we created the first mitochondrial PPI network that is specific to the RA synovial joint tissue. Further, we identified hubs of this network, and moreover, by integrating gene expression and network analysis, we found differentially expressed neighbours of the hub proteins. The results demonstrate that nDNA encoded proteins are (i) crucial for the elevation of mitochondrial reactive oxygen species (ROS) and (ii) involved in membrane potential, transport processes, metabolism and intrinsic apoptosis during RA. Additionally, we proposed a model relating to mitochondrial dysfunction and inflammation in the disease. Our analysis presents a novel perspective on the roles of nDNA encoded proteins in mitochondrial dysfunction, especially in apoptosis, oxidative stress-related processes and their relation to inflammation in RA. These findings provide a plethora of information for further research.

Oral administration of alpha-lipoic acid did not affect lipid peroxidation and antioxidant biomarkers in rheumatoid arthritis patients

Abstract. Rheumatoid arthritis (RA) is a chronic inflammatory disease in which oxidative stress could play a substantial pathological role. Alpha-lipoic acid (ALA) has been known as a “universal” and “ideal” antioxidant. The purpose of this study was to investigate the effects of oral administration of Alpha-lipoic acid (ALA) on lipid peroxidation and antioxidant biomarkers in Rheumatoid arthritis (RA) patients. The study was a randomized, double-blinded, placebo-controlled clinical trial. 70 RA patients were randomized 1:1 to two groups using blocked randomization method and received 1200 mg/day ALA or placebo for 8 weeks. Fasting blood samples were obtained before and after the intervention to analyze total antioxidant capacity (TAC), antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and arylesterase (ARE) activities] and malondialdehyde (MDA). We observed significant increase in serum TAC (0.11 mmol/L; p=0.033) and ARE (13.76 U/mL; p=0.046) and significant decline in MDA (−0.36 nmol/L; p=0.002), in ALA group. However, these changes in ALA-treated group were not statistically significant when compared with placebo-treated group (p > 0.05). Also, within- and between-group differences of whole blood SOD and GSH-Px were not statistically significant (p > 0.05). In conclusion, unexpectedly, ALA therapy did not affect the oxidative status of RA patients in the present clinical trial. It seems that more comprehensive clinical trials in RA patients are still warranted to clarify the effectiveness of ALA which has been known as a potent antioxidant.

Caffeic acid and ellagic acid ameliorate adjuvant-induced arthritis in rats via targeting inflammatory signals, chitinase-3-like protein-1 and angiogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory arthropathy that principally attacks the joints. The present study aimed to explore the potential anti-arthritic effects of caffeic acid and ellagic acid in adjuvant-induced arthritis, compared to celecoxib. The current study also explored the underlying molecular mechanisms e.g., pro-inflammatory signals including chitinase-3-like protein-1 (CHI3L1); a glycoprotein that correlates with RA joint destruction besides angiogenesis, oxidative stres and apoptosis. Interestingly, caffeic and ellagic acids attenuated the severity of arthritis with comparable efficacy to celecoxib. Both agents effectively mitigated paw edema and inflammatory cell infiltration and protected the joint tissues against pannus formation along with cartilage and bone destruction. Notably, they also lowered the paw expression of NF-κB and the downstream effector CHI3L1 and its synthesis inducer IL-1β. They also lowered the levels of the tissue remodeling factor MMP-9 and the angiogenic signal VEGF in rat paws. Both agents also suppressed serum oxidative stress via diminishing lipid peroxides and nitric oxide together with augmentation of reduced glutathione in arthritic animals. Regarding apoptosis, they attenuated paw caspase-3 levels, favoring cell survival. Together, these favorable findings may advocate the use of caffeic and ellagic acids as adjunct modalities for the management of RA to mitigate joint damage.

Inhibition of protein kinase CK2 facilitates cellular senescence by inhibiting the expression of HO-1 in articular chondrocytes

Protein kinase casein kinase 2 (CK2) is important in the regulation of cell proliferation and death, even under pathological conditions. Previously, we reported that CK2 regulates the expression of heme oxygenase‑1 (HO‑1) in stress‑induced chondrocytes. In the present study, it was shown that CK2 is involved in the dedifferentiation and cellular senescence of chondrocytes. Treatment of primary articular chondrocytes with CK2 inhibitors, 4,5,6,7‑terabromo‑2‑azabenzimidazole (TBB) or 5,6‑dichlorobenzimidazole 1‑β‑D‑ribofuranoside (DRB), induced an increase in senescence‑associated β‑galactosidase (SA‑β‑gal) staining. In addition, TBB reduced the expression of type II collagen and stimulated the accumulation of β‑catenin, phenotypic markers of chondrocyte differentiation and dedifferentiation, respectively. It was also observed that the abrogation of CK2 activity by CK2 small interfering RNA induced phenotypes of chondrocyte senescence. The association between HO‑1 and cellular senescence was also examined in CK2 inhibitor‑treated chondrocytes. Pretreatment with 3‑morpholinosydnonimine hydrochloride, an inducer of the HO‑1 expression, or overexpression of the HO‑1 gene significantly delayed chondrocyte senescence. These results show that CK2 is associated with chondrocyte differentiation and cellular senescence and that this is due to regulation of the expression of HO‑1. Furthermore, the findings suggest that CK2 is crucial as an anti‑aging factor during chondrocyte senescence.

Systems-Mapping of Herbal Effects on Complex Diseases Using the Network-Perturbation Signatures

The herbs have proven to hold great potential to improve people's health and wellness during clinical practice over the past millennia. However, herbal medicine for the personalized treatment of disease is still under investigation owing to the complex multi-component interactions in herbs. To reveal the valuable insights for herbal synergistic therapy, we have chosen Traditional Chinese Medicine (TCM) as a case to illustrate the art and science behind the complicated multi-molecular, multi-genes interaction systems, and how the good practices of herbal combination therapy are applicable to personalized treatment. Here, we design system-wide interaction map strategy to provide a generic solution to establish the links between diseases and herbs based on comprehensive testing of molecular signatures in herb-disease pairs. Firstly, we integrated gene expression profiles from 189 diseases to characterize the disease-pathological feature. Then, we generated the perturbation signatures from the huge chemical informatics data and pharmacological data for each herb, which were represented the targets affected by the ingredients in the herb. So that we could assess the effects of herbs on the individual. Finally, we integrated the data of 189 diseases and 502 herbs, yielding the optimal herbal combinations for the diseases based on the strategy, and verifying the reliability of the strategy through the permutation testing and literature verification. Furthermore, we propose a novel formula as a candidate therapeutic drugs of rheumatoid arthritis and demonstrate its therapeutic mechanism through the systematic analysis of the influencing targets and biological processes. Overall, this computational method provides a systematic approach, which blended herbal medicine and omics data sets, allowing for the development of novel drug combinations for complex human diseases.

The dual role of Reactive Oxygen Species in autoimmune and inflammatory diseases: evidence from preclinical models

Reactive oxygen species (ROS) are created in cells during oxidative phosphorylation by the respiratory chain in the mitochondria or by the family of NADPH oxidase (NOX) complexes. The first discovered and most studied of these complexes, NOX2, mediates the oxidative burst in phagocytes. ROS generated by NOX2 are dreadful weapons: while being essential to kill ingested pathogens they can also cause degenerative changes on tissue if production and release are not balanced by sufficient detoxification. In the last fifteen years evidence has been accumulating that ROS are also integral signaling molecules and are important for regulating autoimmunity and immune-mediated inflammatory diseases. It seems that an accurate redox balance is necessary to sustain an immune state that both prevents the development of overt autoimmunity (the bright side of ROS) and minimizes collateral tissue damage (the dark side of ROS). Herein, we review studies from rodent models of arthritis, lupus, and neurodegenerative diseases that show that low NOX2-derived ROS production is linked to disease and elaborate on the underlying cellular and molecular mechanisms and the translation of these results to disease in humans.

Oxidative stress in autoimmune rheumatic diseases

The management of patients with autoimmune rheumatic diseases such as rheumatoid arthritis (RA) remains a significant challenge. Often the rheumatologist is restricted to treating and relieving the symptoms and consequences and not the underlying cause of the disease. Oxidative stress occurs in many autoimmune diseases, along with the excess production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The sources of such reactive species include NADPH oxidases (NOXs), the mitochondrial electron transport chain, nitric oxide synthases, nitrite reductases, and the hydrogen sulfide producing enzymes cystathionine-β synthase and cystathionine-γ lyase. Superoxide undergoes a dismutation reaction to generate hydrogen peroxide which, in the presence of transition metal ions (e.g. ferrous ions), forms the hydroxyl radical. The enzyme myeloperoxidase, present in inflammatory cells, produces hypochlorous acid, and in healthy individuals ROS and RNS production by phagocytic cells is important in microbial killing. Both low molecular weight antioxidant molecules and antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and peroxiredoxin remove ROS. However, when ROS production exceeds the antioxidant protection, oxidative stress occurs. Oxidative post-translational modifications of proteins then occur. Sometimes protein modifications may give rise to neoepitopes that are recognized by the immune system as 'non-self' and result in the formation of autoantibodies. The detection of autoantibodies against specific antigens, might improve both early diagnosis and monitoring of disease activity. Promising diagnostic autoantibodies include anti-carbamylated proteins and anti-oxidized type II collagen antibodies. Some of the most promising future strategies for redox-based therapeutic compounds are the activation of endogenous cellular antioxidant systems (e.g. Nrf2-dependent pathways), inhibition of disease-relevant sources of ROS/RNS (e.g. isoform-specific NOX inhibitors), or perhaps specifically scavenging disease-related ROS/RNS via site-specific antioxidants.

Fisetin Attenuates Metabolic Dysfunction in Mice Challenged with a High-Fructose Diet

Excess fructose consumption can lead to metabolic syndrome, including insulin resistance, dyslipidemia, and hepatic injury, which are associated with oxidative stress and inflammation. The present study was to investigate whether fisetin improved multiple disturbances induced by fructose consumption. First, fisetin was found to be nontoxic to mice after an 8 week treatment. Second, the mice fed with a high-fructose (HFru)-diet for 8 weeks exhibited insulin resistance, dyslipidemia, hepatic injury, oxidative stress, and inflammation. Fisetin supplementation effectively improved the undesirable results mentioned above when compared to the HFru group. Meanwhile, fisetin significantly suppressed the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) pathway and activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in mice fed with HFru. Our findings demonstrated that fisetin exerted the beneficial effects in HFru-feeding mice, which might be associated with suppression of NF-κB and activation of the Nrf2 pathway.

Mitochondrial haplogroups in patients with rheumatoid arthritis: No association with disease and disease manifestations

OBJECTIVE

To describe the distribution of specific mitochondrial DNA (mtDNA) haplogroups (hgs) in a cohort of patients with rheumatoid arthritis (RA).

METHODS

Two-hundred nineteen consecutive patients with RA had mtDNA isolated from their blood, sequenced and haplotyped. Patients were diagnosed according to the American College of Rheumatology (ACR)/European league against Rheumatism (EULAR) criteria. Demographic and clinical data were retrieved from the Danish nationwide database (DANBIO). Logistic regression analyses were performed to test for associations.

RESULTS

One-hundred eighty-four patients were eligible for analysis. Haplogroup frequencies were: H (n = 88; 47.8%), U (n = 37; 20.1%), T (n = 22; 12.0%), J (n = 16; 8.7%), K (n = 11; 5.9%), HV (n = 6; 3.3%) and V (n = 4; 2.2%). The distribution of individual hgs was identical to the background population. Radiographic erosions were significantly associated with hg clusters JT (OR = 2.37, 95% confidence interval (CI): 1.07-5.53, p = 0.038). Significantly fewer patients from hg cluster JT received biological treatment (OR = 0.17, 95% CI: 0.03-0.87, p = 0.038). Albeit, none of these associations were significant when corrected for multiple tests.

CONCLUSION

There was no significant association between mtDNA hgs and presence of RA or disease manifestations. There was an, albeit insignificant, overrepresentation of patients with hg JT among patients with erosive disease; however, slightly fewer patients in the JT group were treated with biological drugs.

Redox regulation in metabolic programming and inflammation

Energy metabolism and redox state are intrinsically linked. In order to mount an adequate immune response, cells must have an adequate and rapidly available energy resource to migrate to the inflammatory site, to generate reactive oxygen species using NADPH as a cofactor and to engulf bacteria or damaged tissue. The first responder cells of the innate immune response, neutrophils, are largely dependent on glycolysis. Neutrophils are relatively short-lived, dying via apoptosis in the process of bacterial killing through production of hypochlorous acid and release of extracellular NETs. Later on, the most prevalent recruited innate immune cells are monocytes. Their role is to complete a damage limitation exercise initiated by neutrophils and then, as re-programmed M2 macrophages, to resolve the inflammatory event. Almost twenty five years ago, it was noted that macrophages lose their glycolytic capacity and become anti-inflammatory after treatment with corticosteroids. In support of this we now understand that, in contrast to early responders, M2 macrophages are predominantly dependent on oxidative phosphorylation for energy. During early inflammation, polarisation towards M1 macrophages is dependent on NOX2 activation which, via protein tyrosine phosphatase oxidation and AKT activation, increases trafficking of glucose transporters to the membrane and consequently increases glucose uptake for glycolysis. In parallel, mitochondrial efficiency is likely to be compromised via nitrosylation of the electron transport chain. Resolution of inflammation is triggered by encounter with apoptotic membranes exposing oxidised phosphatidylserine that interact with the scavenger receptor, CD36. Downstream of CD36, activation of AMPK and PPARγ elicits mitochondrial biogenesis, arginase expression and a switch towards oxidative phosphorylation in the M2 macrophage. Proinflammatory cytokine production by M2 cells decreases, but anti-inflammatory and wound healing growth factor production is maintained to support restoration of normal function.

Carvedilol can attenuate histamine-induced paw edema and formaldehyde-induced arthritis in rats without risk of gastric irritation

BACKGROUND AND AIM

Rheumatoid arthritis treatment aims to control joint damage and any associated complications such as cardiovascular disease. Most anti-inflammatory drugs have a high tendency to cause gastro-intestinal irritation. The present study is designed to investigate the anti-inflammatory effect of carvedilol and to study its effect on gastric mucosa.

EXPERIMENTAL APPROACH

Lornoxicam (1.3mg/kg) or carvedilol (10mg/kg) was administrated orally 1h before histamine injection into animals of a histamine-induced paw edema model and orally daily for 11days into animals of a formaldehyde-induced arthritis model. Tumor necrosis factor-α and prostaglandin E₂ were measured in animals of the formaldehyde-induced arthritis model. The effect of lornoxicam and carvedilol on gastric mucosa was assessed in normal rats and after induction of cold stress ulcer.

RESULTS

Carvedilol succeeded in reducing hind paw edema in both histamine-induced paw edema and formaldehyde-induced arthritis and in reducing the elevated level of tumor necrosis factor-α and prostaglandin E₂ nearly with near equal efficacy compared with lornoxicam. Carvedilol did not show any ulcerative effect on the gastric mucosa of normal rats, and its use was associated with an improvement of both the gross and histopathological pictures of gastric ulcers in animals of the cold stress ulcer model compared with lornoxicam treated rats.

CONCLUSION

The current findings support the use of carvedilol both in the management of inflammation as well as the prevention of cardiovascular complications in rheumatoid arthritis patients. The use of carvedilol was not associated with any gastro-intestinal tract irritation.

Pharmacological studies on the anti-inflammatory and immunomodulatory role of pentoxifylline and its interaction with nitric oxide (NO) in experimental arthritis in rats

AIM

Present study was designed to evaluate protective effects of pentoxifylline and its potentiation with low dose of nitric oxide (NO) modulators in adjuvant-induced experimental arthritis in rats.

METHOD

Wistar rats (200-300 g, n = 8 per group) of both sexes were used in the study. On day "0" experimental arthritis was induced by injecting 0.2 ml of Complete Freund's adjuvant (CFA) in sub-planter region of right hind paw of animals. Pentoxifylline treatment alone and in combination with NO modulators was given (i.p.) from day 14 to 28. Various arthritic parameters were recorded and blood and joint synovial fluid was collected for biochemical analysis.

RESULTS

CFA inoculation significantly increases (1) arthritic index (2) ankle diameter (3) paw volume (4) histopathology score (5) serum TNF-α, IL-6, IL-1β and synovial TNF-α levels (p < 0.001) (6) serum Th₁ and Th₂ cytokine levels g) MDA levels in rat paw tissue homogenates (7) serum NF-κB levels. Significant decrease in serum IL-10 levels and SOD activity was observed in rats after CFA inoculation. Decrease in body weight and suppressed general quality of life of CFA inoculated rats was also observed. These CFA-induced arthritic changes were significantly reversed by pentoxifylline alone and in combination with low dose of NO modulators (p < 0.05).

CONCLUSION

These results are suggestive of protective effects of pentoxifylline and its potentiation in combination with low dose of NO modulators. These results may provide new pharmacological therapy for management of rheumatoid arthritis (RA).

The Association Between Serum Selenium Levels with Rheumatoid Arthritis

There are conflicting reports on the correlation between serum selenium (Se) levels with rheumatoid arthritis (RA). Through a meta-analysis approach, the aim of the present study is to clarify the relationship between serum Se levels with RA. We searched literatures that met our predefined criteria in PubMed, ScienceDirect, and OVID published as of September 2015. Ten eligible articles with 14 case-control studies involving 716 subjects were identified. Overall, pooled analysis indicated that subjects with RA had lower serum levels of Se than the healthy controls (standardized mean difference (SMD) = -1.347, 95 % confidence interval (CI) = [-1.872, -0.823], p < 0.001). Further subgroup analysis indicated that subjects with RA had lower serum Se levels than healthy controls in Europe (SMD = -1.063, 95 % CI = [-1.571, -0.556], p < 0.001) and Asia (SMD = -3.254, 95 % CI = [-4.687, -1.821], p < 0.001) but not in USA (SMD = -0.322, 95 % CI = [-0.657, 0.012], p = 0.059). The serum Se levels were lower in RA than healthy controls measured by graphite furnace atom absorption spectrometry (GFAAS) (SMD = -1.026, 95 % CI = [-1.522, -0.530], p < 0.001), electrothermal absorption spectrometry (EAS) (SMD = -1.197, 95 % CI = [-2.373, -0.020], p < 0.05), flame atomic absorption spectrophotometry (FAAS) (SMD = -0.681, 95 % CI = [-1.049, -0.313], p < 0.001), and inductively coupled plasma-mass spectrophotometer (ICP-MS) (SMD = -11.707, 95 % CI = [-15.189, -8.224], p < 0.001) but not by neutron activation analysis (NAA) (SMD = -0.674, 95 % CI = [-1.350, 0.003], p = 0.051). In conclusion, this meta-analysis supports a significant association between low serum Se concentration with RA. However, this finding needs further confirmation by a trans-regional multicenter study to obtain better understanding of causal relationship between serum Se with RA of different human races or regions.

iNOS null MRL+/+ mice show attenuation of trichloroethene-mediated autoimmunity: contribution of reactive nitrogen species and lipid-derived reactive aldehydes

Earlier studies from our laboratory in MRL+/+ mice suggest that free radicals, especially overproduction of reactive nitrogen species (RNS) and lipid-derived reactive aldehydes (LDRAs), are associated with trichloroethene (TCE)-mediated autoimmune response. The current study was undertaken to further assess the contribution of RNS and LDRAs in TCE-mediated autoimmunity by using iNOS-null MRL+/+ mice. iNOS-null MRL+/+ mice were obtained by backcrossing iNOS-null mice (B6.129P2-Nos2(tm1Lau)/J) to MRL +/+ mice. Female MRL+/+ and iNOS-null MRL+/+ mice were given TCE (10 mmol/kg, i.p., every 4(th) day) for 6 weeks; their respective controls received corn oil only. TCE exposure led to significantly increased iNOS mRNA in livers, iNOS protein in livers and sera, increased nitrotyrosine (NT) formation in both livers and sera, induction of MDA-/HNE-protein adducts in livers and their respective antibodies in sera along with significant increases in serum antinuclear antibodies (ANA) and anti-dsDNA in MRL+/+ mice. Even though in iNOS-null MRL+/+ mice, the iNOS and NT levels were negligible in both TCE-treated and untreated groups, TCE treatment still led to significant increases in MDA-/HNE-protein adducts and their respective antibodies along with increases in serum ANA and anti-dsDNA compared to controls. Most remarkably, the increases in serum ANA and anti-dsDNA induced by TCE in the iNOS-null MRL+/+ mice were significantly less pronounced compared to that in MRL+/+ mice. Our results provide further evidence that both RNS and LDRAs contribute to TCE-induced autoimmunity in MRL+/+ mice, and iNOS deficiency attenuates this autoimmune response.

Loss in MCL-1 function sensitizes non-Hodgkin's lymphoma cell lines to the BCL-2-selective inhibitor venetoclax (ABT-199)

As a population, non-Hodgkin's lymphoma (NHL) cell lines positive for the t(14;18) translocation and/or possessing elevated BCL2 copy number (CN; BCL2(High)) are exquisitely sensitive to navitoclax or the B-cell lymphoma protein-2 (BCL-2)-selective inhibitor venetoclax. Despite this, some BCL2(High) cell lines remain resistant to either agent. Here we show that the MCL-1-specific inhibitor A-1210477 sensitizes these cell lines to navitoclax. Chemical segregation of this synergy with the BCL-2-selective inhibitor venetoclax or BCL-XL-selective inhibitor A-1155463 indicated that MCL-1 and BCL-2 are the two key anti-apoptotic targets for sensitization. Similarly, the CDK inhibitor flavopiridol downregulated MCL-1 expression and synergized with venetoclax in BCL2(High) NHL cell lines to a similar extent as A-1210477. A-1210477 also synergized with navitoclax in the majority of BCL2(Low) NHL cell lines. However, chemical segregation with venetoclax or A-1155463 revealed that synergy was driven by BCL-XL inhibition in this population. Collectively these data emphasize that BCL2 status is predictive of venetoclax potency in NHL not only as a single agent, but also in the adjuvant setting with anti-tumorigenic agents that inhibit MCL-1 function. These studies also potentially identify a patient population (BCL2(Low)) that could benefit from BCL-XL (navitoclax)-driven combination therapy.

Aggregation of rare/low-frequency variants of the mitochondria respiratory chain-related proteins in rheumatoid arthritis patients

Exome sequencings were conducted using 59 patients having rheumatoid arthritis (RA) and 93 controls. After stepwise filtering, 107 genes showed less than 0.05 of P-values by gene-burden tests. Among 107 genes, NDUFA7 which is a subunit of the complex I in the mitochondrial respiratory chain was selected for further analysis based on previous reports. A case-control study was performed on the three single-nucleotide variants (SNVs) of NDUFA7 with 432 cases and 432 controls. An association was observed between NDUFA7 and RA with severe erosive arthritis. These results together with previous reports suggested the involvement of reactive oxygen species (ROS) in the pathogenesis of RA. In the next step, four SNVs from three genes related to the mitochondrial respiratory chain were selected, which is a major source of ROS, and conducted a case-control study. An association was observed based on a pathway-burden test comprising NDUFA7, SDHAF2, SCO1 and ATP5O: P=1.56E-04, odds ratio=2.16, 95% confidence interval=1.43-3.28. Previous reports suggested the involvement of ROS in the pathogenesis of RA. The aggregation of SNVs in the mitochondria respiratory chain suggests the pivotal role of those SNVs in the pathogenesis of RA with severe erosive arthritis.

MCL-1 Is a Key Determinant of Breast Cancer Cell Survival: Validation of MCL-1 Dependency Utilizing a Highly Selective Small Molecule Inhibitor

Hyperexpression of antiapoptotic BCL-2 family proteins allows cells to survive despite the receipt of signals that would ordinarily induce their deletion, a facet frequently exploited by tumors. Tumors addicted to the BCL-2 family proteins for survival are now being targeted therapeutically. For example, navitoclax, a BCL-2/BCL-XL/BCL-W inhibitor, is currently in phase I/II clinical trials in numerous malignancies. However, the related family member, MCL-1, limits the efficacy of navitoclax and other chemotherapeutic agents. In the present study, we identify breast cancer cell lines that depend upon MCL-1 for survival and subsequently determine the mechanism of apoptosis mediated by the MCL-1 selective inhibitor A-1210477. We demonstrate that apoptosis resulting from a loss in MCL-1 function requires expression of the proapoptotic protein BAK. However, expression of BCL-XL can limit apoptosis resulting from loss in MCL-1 function through sequestration of free BIM. Finally, we demonstrate substantial synergy between navitoclax and MCL-1 siRNA, the direct MCL-1 inhibitor A-1210477, or the indirect MCL-1 inhibitor flavopiridol, highlighting the therapeutic potential for inhibiting BCL-XL and MCL-1 in breast cancer.

Inhibition of inflammatory arthritis using fullerene nanomaterials

Inflammatory arthritis (e.g. rheumatoid arthritis; RA) is a complex disease driven by the interplay of multiple cellular lineages. Fullerene derivatives have previously been shown to have anti-inflammatory capabilities mediated, in part, by their ability to prevent inflammatory mediator release by mast cells (MC). Recognizing that MC can serve as a cellular link between autoantibodies, soluble mediators, and other effector populations in inflammatory arthritis, it was hypothesized that fullerene derivatives might be used to target this inflammatory disease. A panel of fullerene derivatives was tested for their ability to affect the function of human skin-derived MC as well as other lineages implicated in arthritis, synovial fibroblasts and osteoclasts. It is shown that certain fullerene derivatives blocked FcγR- and TNF-α-induced mediator release from MC; TNF-α-induced mediator release from RA synovial fibroblasts; and maturation of human osteoclasts. MC inhibition by fullerene derivatives was mediated through the reduction of mitochondrial membrane potential and FcγR-mediated increases in cellular reactive oxygen species and NF-κB activation. Based on these in vitro data, two fullerene derivatives (ALM and TGA) were selected for in vivo studies using K/BxN serum transfer arthritis in C57BL/6 mice and collagen-induced arthritis (CIA) in DBA/1 mice. Dye-conjugated fullerenes confirmed localization to affected joints in arthritic animals but not in healthy controls. In the K/BxN moldel, fullerenes attenuated arthritis, an effect accompanied by reduced histologic inflammation, cartilage/bone erosion, and serum levels of TNF-α. Fullerenes remained capable of attenuating K/BxN arthritis in mast cell-deficient mice Cre-Master mice, suggesting that lineages beyond the MC represent relevant targets in this system. These studies suggest that fullerene derivatives may hold promise both as an assessment tool and as anti-inflammatory therapy of arthritis.

A novel therapeutic approach targeting rheumatoid arthritis by combined administration of morin, a dietary flavanol and non-steroidal anti-inflammatory drug indomethacin with reference to pro-inflammatory cytokines, inflammatory enzymes, RANKL and transcription factors

The present study was designed to assess the combined efficacy of morin, a dietary flavanol and non-steroidal anti-inflammatory drug indomethacin against adjuvant-induced arthritis in rats, an experimental model for rheumatoid arthritis. Arthritis was induced by intradermal injection of complete freund's adjuvant (0.1 ml) into the right hind paw of the Wistar albino rats. Morin (30 mg/kg b.wt), indomethacin (3 mg/kg b.wt) and combination of morin and indomethacin were administered intraperitoneally (from 11th to 20th day) after adjuvant injection. We have found that the activities/levels of lysosomal acid hydrolases (acid phosphatase, β-galactosidase, N-acetyl glucosaminidase and cathepsin-D), glycoproteins (hexose and hexosamine), urinary constituents (hydroxyproline and glycosaminoglycans), reactive oxygen species (LPO and NO), elastase, inflammatory mediators (TNF-α, IL-1β, MCP-1, VEGF and PGE2) and paw edema were significantly increased in arthritic rats compared to controls. Whereas, the anti-oxidant status (SOD, CAT, GPx, glutathione, and ceruloplasmin), body weight and bone collagen was found to be decreased. The mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-17, IL-6 and MCP-1), inflammatory enzymes (iNOS and COX-2), RANKL, and transcription factors (NF-kB p65 and AP-1) was found upregulated in the ankle joints of arthritic rats in qRT-PCR analysis. In addition, the increased protein expression of NF-kB p65 and COX-2 was also detected by immunohistochemical analysis. On the other hand, the above said imbalances were regulated back effectively to near normal as evidenced by the histopathological and radiological analysis on combined treatment with morin and indomethacin. Our study indicates that the combination therapy was more effective than either single drug alone in suppressing the pathogenesis of RA.

Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters

Many diseases are associated with oxidative stress, which occurs when the production of reactive oxygen species (ROS) overwhelms the scavenging ability of an organism. Here, we evaluated the carbon nanoparticle antioxidant properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs) by electron paramagnetic resonance (EPR) spectroscopy, oxygen electrode, and spectrophotometric assays. These carbon nanoparticles have 1 equivalent of stable radical and showed superoxide (O2 (•-)) dismutase-like properties yet were inert to nitric oxide (NO(•)) as well as peroxynitrite (ONOO(-)). Thus, PEG-HCCs can act as selective antioxidants that do not require regeneration by enzymes. Our steady-state kinetic assay using KO2 and direct freeze-trap EPR to follow its decay removed the rate-limiting substrate provision, thus enabling determination of the remarkable intrinsic turnover numbers of O2 (•-) to O2 by PEG-HCCs at >20,000 s(-1). The major products of this catalytic turnover are O2 and H2O2, making the PEG-HCCs a biomimetic superoxide dismutase.

Anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal are mediated by inhibition of the STAT3 pathway

BACKGROUND AND PURPOSE

Products of Maillard reactions between aminoacids and reducing sugars are known to have anti-inflammatory properties. Here we have assessed the anti-arthritis effects of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal and its possible mechanisms of action.

EXPERIMENTAL APPROACH

We used cultures of LPS-activated macrophages (RAW264.7 cells) and human synoviocytes from patients with rheumatoid arthritis for in vitro assays and the collagen-induced arthritis model in mice. NO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities were measured in vitro and in joint tissues of arthritic mice, along with clinical scores and histopathological assessments. Binding of (E)-2,4-bis(p-hydroxyphenyl)-2-butenal to STAT3 was evaluated by a pull-down assay and its binding site was predicted using molecular docking studies with Autodock VINA.

KEY RESULTS

(E)-2,4-bis(p-hydroxyphenyl)-2-butenal (2.5-10 μg·mL(-1) ) inhibited LPS-inducedNO generation, iNOS and COX2 expression, and NF-κB/IKK and STAT3 activities in macrophage and human synoviocytes. This compound also suppressedcollagen-induced arthritic responses in mice by inhibiting expression of iNOS and COX2, and NF-κB/IKK and STAT3 activities; it also reduced bone destruction and fibrosis in joint tissues. A pull-down assay showed that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal interfered with binding of ATP to STAT3. Docking studies suggested that (E)-2,4-bis(p-hydroxyphenyl)-2-butenal bound to the DNA-binding interface of STAT3 possibly inhibiting ATP binding to STAT3 in an allosteric manner.

CONCLUSIONS AND IMPLICATIONS

(E)-2,4-bis(p-hydroxyphenyl)-2-butenal exerted anti-inflammatory and anti-arthritic effects through inhibition of the NF-κB/STAT3 pathway by direct binding to STAT3. This compound could be a useful agent for the treatment of arthritic disease.

Optimized "in vitro" culture conditions for human rheumatoid arthritis synovial fibroblasts

The composition of synovial fluid in rheumatoid arthritis (RA) is complex and strongly influences the microenvironment of joints and it is an inseparable element of the disease. Currently, “in vitro” studies are performed on RA cells cultured in the presence of either recombinant proinflammatory cytokines-conditioned medium or medium alone. In this study, we evaluated the use of synovial fluid, derived from RA patients, as optimal culture condition to perform “in vitro” studies on RA synovial fibroblasts. We observed that synovial fluid is more effective in inducing cell proliferation with respect to TNF-alpha or culture medium alone. Spontaneous apoptosis in fibroblasts was also decreased in response to synovial fluid. The expression of proinflammatory cytokines in the presence of synovial fluid was significantly elevated with respect to cells cultured with TNF-alpha or medium, and the overall morphology of cells was also modified. In addition, modulation of intracellular calcium dynamics elicited in response to synovial fluid or TNF-alpha exposure is different and suggests a role for the purinergic signalling in the modulation of the effects. These results emphasize the importance of using RA synovial fluid in “in vitro” studies involving RA cells, in order to reproduce faithfully the physiopathological environmental characteristic of RA joints.

Hydrophilic carbon clusters as therapeutic, high-capacity antioxidants

Oxidative stress reflects an excessive accumulation of reactive oxygen species (ROS) and is a hallmark of several acute and chronic human pathologies. Although many antioxidants have been investigated, most have demonstrated poor efficacy in clinical trials. Here we discuss the limitations of current antioxidants and describe a new class of nanoparticle antioxidants, poly(ethylene glycol)-functionalized hydrophilic carbon clusters (PEG-HCCs). PEG-HCCs show high capacity to annihilate ROS such as superoxide (O2(•-)) and the hydroxyl (HO(•)) radical, show no reactivity toward the nitric oxide radical (NO(•)), and can be functionalized with targeting moieties without loss of activity. Given these properties, we propose that PEG-HCCs offer an exciting new area of study for the treatment of numerous ROS-induced human pathologies.

[Higher nitric oxide levels are associated with disease activity in Egyptian rheumatoid arthritis patients]

BACKGROUND

Oxidative stress generated within inflammatory joints can produce autoimmune phenomena and joint destruction. Radical species with oxidative activity, including reactive nitrogen species, represent mediators of inflammation and cartilage damage.

OBJECTIVES

To assess serum nitric oxide as a marker of oxidative stress in Egyptian patients with rheumatoid arthritis and its relation to disease activity.

METHODS

80 patients with rheumatoid arthritis were divided into 2 groups, according to the DAS-28 score: Group I: 42 patients with disease activity, and Group II: 38 patients with no disease activity. Forty age- and sex-matched individuals were included as control group (Group III). Routine laboratory investigations were done, and nitric oxide was measured using Elisa. Hand plain radiographies were done for radiological status scoring using the Sharp method.

RESULTS

A comparison between nitric oxide in all three groups showed a highly significant difference (p < 0.001), significantly higher levels were obtained among rheumatoid arthritis patients in comparison to controls, and higher levels were obtained in patients with active disease (mean±SD 82.38±20.46) in comparison to patients without active disease (35.53±7.15). Nitric oxide in Group I showed a significant positive correlation with morning stiffness (r=0.45), arthritis (r=0.43), platelet count (r=0.46), erythrocyte sedimentation rate (r=0.83), C-reactive protein (r=0.76) and Disease Activity Score (r=0.85). Nitric oxide showed a significant positive correlation (r=0.43) with hand radiographies (Sharp score) in Group I.

CONCLUSION

There are increased levels of nitric oxide in the serum of patients with rheumatoid arthritis. Nitric oxide correlates significantly with disease activity, inflammatory markers and radiological joint status.

Thioredoxin as a putative biomarker and candidate target in age-related immune decline

The oxidoreductase Trx-1 (thioredoxin 1) is highly conserved and found intra- and extra-cellularly in mammalian systems. There is increasing interest in its capacity to regulate immune function based on observations of altered distribution and expression during ageing and disease. We have investigated previously whether extracellular T-cell or peripheral blood mononuclear cell Trx-1 levels serve as a robust marker of ageing. In a preliminary study of healthy older adults compared with younger adults, we showed that there was a significant, but weak, relationship with age. Interestingly, patients with rheumatoid arthritis and cancer have been described by others to secrete or express greater surface Trx-1 than predicted. It is interesting to speculate whether a decline in Trx-1 during ageing protects against such conditions, but correspondingly increases risk of disease associated with Trx-1 depletion such as cardiovascular disease. These hypotheses are being explored in the MARK-AGE study, and preliminary findings confirm an inverse correlation of surface Trx-1 with age. We review recent concepts around the role of Trx-1 and its partners in T-cell function on the cell surface and as an extracellular regulator of redox state in a secreted form. Further studies on the redox state and binding partners of surface and secreted Trx-1 in larger patient datasets are needed to improve our understanding of why Trx-1 is important for lifespan and immune function.

The impact of DMARD and anti-TNF therapy on functional characterization of short-term T-cell activation in patients with rheumatoid arthritis--a follow-up study

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a systemic dysfunction of T-cells. In this study we tested the impact of DMARD and anti-TNF agents on short-term activation characteristics of T-cells. We enrolled 12 patients with newly diagnosed RA (naïve RA) who were treated with methothrexate (MTX) and glucocorticsteroid (GCS) and 22 patients with established RA non responding to conventional DMARD therapy who were treated with different anti-TNF agents. Nine healthy volunteers served as controls. Blood samples were taken at baseline, then at 4th and 8th week of therapy. The characteristics of several intracellular activation processes during short-term activation of T-cells including cytoplasmic Ca(2+) level, mitochondrial Ca(2+) level, reactive oxygen species (ROS) and nitric oxide (NO) generation were determined by a novel flow-cytometry technique. At baseline, the tested processes were comparable to controls in naïve RA. During GCS therapy, cytoplasmic Ca(2+) level and ROS generation decreased. After the addition of MTX to GCS cytoplasmic Ca(2+) level became comparable to controls, while ROS generation decreased further. In DMARD non responders, cytoplasmic Ca(2+) level was higher than controls at baseline. The cytoplasmic Ca(2+) level became comparable to controls and ROS generation decreased during each of the three anti-TNF-α agent therapies. Mitochondrial Ca(2+) level and NO generation were unaltered in all of the patient groups. These results indicate that intracellular machinery is affected in T-cells of RA patients. This may alter the behavior of T-cells during activation. Different therapeutic approaches may modulate the abnormal T-cell functions.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

Therapeutic efficacy of infused molecular hydrogen in saline on rheumatoid arthritis: a randomized, double-blind, placebo-controlled pilot study

The aim of this study was to demonstrate the safety and efficacy of H2-saline infusion for treatment of rheumatoid arthritis (RA). We conducted a randomized, double-blind, placebo-controlled investigation of the infusion of 1 ppm H2-dissolved saline (H2-saline) in 24 RA patients. Patients were randomized 1:1 to receive 500 ml of either H2-saline or placebo-saline, which was drop infused intravenously (DIV) daily for 5 days. The disease activity score in 28 joints (DAS28) was measured at baseline, immediately post infusion, and after 4 weeks. Therapeutic effects of H2-saline on joint inflammation were estimated by measuring serum biomarkers for RA, tumor necrosis factor-α (TNFα), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), and urinary 8-hydroxydeoxyguanosine (8-OHdG). In the H2-infused group, average DAS28 decreased from 5.18 ± 1.16 to 4.02 ± 1.25 immediately post infusion and reached 3.74 ± 1.22 after 4 weeks. No significant decrease in DAS28 was observed in the placebo group throughout the study. IL-6 levels in the H2 group significantly decreased in 4 weeks by 37.3 ± 62.0% compared to baseline, whereas it increased by 33.6 ± 34.4% in the placebo group. TNFα levels did not change remarkably in the H2 or placebo groups in 4 weeks post-infusion compared to baseline. The relative ratio of 8-OHdG in the H2 group also significantly decreased by 4.7%. After 4 weeks, MMP3 was significantly reduced by 19.2% ± 24.6% in the H2 group, and increased by 16.9% ± 50.2% in the placebo group. Drop infusion of H2 safely and effectively reduced RA disease activity.

Nitrosative stress and nitrated proteins in trichloroethene-mediated autoimmunity

Exposure to trichloroethene (TCE), a ubiquitous environmental contaminant, has been linked to a variety of autoimmune diseases (ADs) including SLE, scleroderma and hepatitis. Mechanisms involved in the pathogenesis of ADs are largely unknown. Earlier studies from our laboratory in MRL+/+ mice suggested the contribution of oxidative/nitrosative stress in TCE-induced autoimmunity, and N-acetylcysteine (NAC) supplementation provided protection by attenuating oxidative stress. This study was undertaken to further evaluate the contribution of nitrosative stress in TCE-mediated autoimmunity and to identify proteins susceptible to nitrosative stress. Groups of female MRL +/+ mice were given TCE, NAC or TCE + NAC for 6 weeks (TCE, 10 mmol/kg, i.p., every 4^th day; NAC, ∼250 mg/kg/day via drinking water). TCE exposure led to significant increases in serum anti-nuclear and anti-histone antibodies together with significant induction of iNOS and increased formation of nitrotyrosine (NT) in sera and livers. Proteomic analysis identified 14 additional nitrated proteins in the livers of TCE-treated mice. Furthermore, TCE exposure led to decreased GSH levels and increased activation of NF-κB. Remarkably, NAC supplementation not only ameliorated TCE-induced nitrosative stress as evident from decreased iNOS, NT, nitrated proteins, NF-κB p65 activation and increased GSH levels, but also the markers of autoimmunity, as evident from decreased levels of autoantibodies in the sera. These findings provide support to the role of nitrosative stress in TCE-mediated autoimmune response and identify specific nitrated proteins which could have autoimmune potential. Attenuation of TCE-induced autoimmunity in mice by NAC provides an approach for designing therapeutic strategies.