Regulation of B lymphocytes and plasma cells by innate immune mechanisms and stromal cells in rheumatoid arthritis

The role of lactylation in plasma cells and its impact on rheumatoid arthritis pathogenesis: insights from single-cell RNA sequencing and machine learning

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by persistent synovitis, systemic inflammation, and autoantibody production. This study aims to explore the role of lactylation in plasma cells and its impact on RA pathogenesis.

Methods

We utilized single-cell RNA sequencing (scRNA-seq) data and applied bioinformatics and machine learning techniques. A total of 10,163 cells were retained for analysis after quality control. Clustering analysis identified 13 cell clusters, with plasma cells displaying the highest lactylation scores. We performed pathway enrichment analysis to examine metabolic activity, such as oxidative phosphorylation and glycolysis, in highly lactylated plasma cells. Additionally, we employed 134 machine learning algorithms to identify seven core lactylation-promoting genes and constructed a diagnostic model with an average AUC of 0.918.

Results

The RA lactylation score (RAlac_score) was significantly elevated in RA patients and positively correlated with immune cell infiltration and immune checkpoint molecule expression. Differential expression analysis between two plasma cell clusters revealed distinct metabolic and immunological profiles, with cluster 2 demonstrating increased immune activity and extracellular matrix interactions. qRT-PCR validation confirmed that NDUFB3, NGLY1, and SLC25A4 are highly expressed in RA.

Conclusion

This study highlights the critical role of lactylation in plasma cells for RA pathogenesis and identifies potential biomarkers and therapeutic targets, which may offer insights for future therapeutic strategies.

Network pharmacology analysis and clinical verification of Jishe Qushi capsules in rheumatoid arthritis treatment

The study aimed to elucidate the effective chemical composition and molecular mechanism of rheumatoid arthritis (RA) treatment with Jishe Qushi capsules (JSQS) and perform clinical validation. The effective chemical components were screened by a database. We used Cytoscape software to construct the key target-RA composite target network of JSQS. Gene Ontology biofunctional analysis and Kyoto encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed for the key targets, followed by molecular docking validation of core key targets. Ninety-nine patients chosen were divided into 49 cases in the treatment group and 50 cases in the control group according to the random number table method. The control group was treated with the combination of methotrexate (MTX) plus Glucosidorum Tripterygll Totorum. The treatment group was treated with MTX plus JSQS. The treatment effects of the 2 groups were evaluated. A total of 118 key anti-RA targets were obtained for JSQS. Quercetin in Panax notoginseng, vanillic acid, scopoletin, physcion in Gardneria angustifolia, 3,5-dimethyl-4-hydroxybenzaldehyde in Zaocys dhumnades, kaempferol in Radix Paeoniae Alba, and protocatechuic aldehyde in Cibotium barometz were the main active chemical components in the composite target network. Topology analysis yields core key targets, such as TP53, INS, IL6, VEGFA, MYC, CASP3, ESR1, EGF, CCND1, PPARG, ERBB2, NFKBIA, TLR4, RELA, and CASP8, and the results of KEGG enrichment analysis showed that JSQS mainly works through pathways in cancer, phosphatidylinositol-3-kinaseRAC-serine/threonine-protein kinase signaling, and mitogen-activated protein kinase (MAPK) signaling pathway, and aryl hydrocarbon receptor nuclear translocator signaling pathway. Molecular docking results showed that the binding fraction of PPARG, VEGFA and the effective active ingredients of ridged snake dispelling capsule was >70. In the clinical trial, morning stiffness, joint pain, and VAS scores of post-treatment in the treatment group were lower than those in the control group (P < .05). Additionally, ESR, CRP, RF, anti-CCP, TNF-α, IL-6, IL-17, and Th17/Treg were lower in the treatment group than in the control group (P < .05). JSQS exert multicomponent, multipathway, and multitarget synergistic actions in RA treatment. It can significantly improve the clinical symptoms and quality of life and delay the progression of RA disease.

[Clinical characteristics and risk factors of rheumatoid arthritis with ulcerative keratitis]

OBJECTIVE

To investigate the clinical characteristics, risk factors and prognosis of ulcerative keratitis (UK) in patients with rheumatoid arthritis (RA).

METHODS

Sixteen patients with UK (the UK group) were screened among 4 773 RA patients hospitalized at Peking University People's Hospital from January 2003 to May 2021, and 72 patients with RA without UK in the control group were selected by propensity score matching (PSM). The clinical features, laboratory data and medications between the two groups were collected and analyzed.

RESULTS

The average age of the patients with RA was 60 years at the time of the complication of UK. UK appeared on average in the 16th year of RA, with the majority of UK occurring in the 7th year of RA and beyond (14 cases), however, a minority of UK was the first symptom of RA (1 case). UK associated with RA manifested as simple marginal UK in 8 cases, marginal UK with perforation in 5 cases, marginal UK with uveitis in 2 cases and central UK with perforation in 1 case. The number of swollen joints was significantly higher in the UK group than in the control group [6.0(2.5, 23.0) vs. 3.0(1.0, 9.8), Z=-2.047, P=0.041], and the proportion of secondary Sjögren syndrome (SS, 37.5% vs. 6.9%, χ²=11.175, P=0.004) and interstitial lung disease (ILD, 37.5% vs. 8.3%, χ²=9.456, P=0.008) were significantly higher in the RA patients with UK than the patients without UK. The uses of sulfasalazine (12.5% vs. 48.6%, χ²=7.006, P=0.008), leflunomide (31.3% vs. 63.9%, χ²=5.723, P=0.017) and gold salt(6.3% vs. 33.8%, χ²=4.841, P=0.032)were significantly lower in the UK group than in the control group. However, there was no statistically significant comparison between the two groups for the 28-joint disease activity score-erythrocyte sedimentation rate (5.3±1.8 vs. 5.1±1.6, t=0.309, P=0.761). Logistic analysis showed the number of swollen joints (OR=1.148), secondary SS (OR=79.118), complicated with ILD (OR=6.596) and the use of sulfasalazine (OR=0.037) were independent relevant factors (P < 0.05) for UK in RA patients.

CONCLUSION

The number of swollen joints, secondary SS, complicated with ILD and the use of sulfasalazine are independent relevant factors for UK in patients with RA.

Epigenetically-regulated RPN2 gene influences lymphocyte activation and is involved in pathogenesis of rheumatoid arthritis

BACKGROUND

To identify RA-associated genes and to ascertain epigenetic factors and functional mechanisms underlying RA pathogenesis.

METHODS

Peripheral blood mononuclear cells (PBMC) transcriptome- and proteome- wide gene expressions were profiled in a case-control study sample. Differentially expressed genes (DEGs) were discovered and validated independently. In-house PBMC genome-wide SNP genotyping data, miRNA expression data and DNA methylation data in the same sample were utilized to identify SNPs [expression quantitative trait locus (eQTLs) and protein quantitative trait locus (pQTLs)], miRNAs, and DNA methylation positions (DMPs) regulating key DEG of interest. Lentivirus transfection was conducted to study the effects of RPN2 on T lymphocyte activation, proliferation, apoptosis, and inflammatory cytokine expression. Rpn2 protein level in plasma was quantitated by ELISA to assess its performance in discriminating RA cases and controls.

RESULTS

Twenty-two DEGs were discovered in PBMCs. The most significant DEG, i.e., RPN2, was validated to be up-regulated with RA in PBMCs. A complex regulatory network for RPN2 gene expression in PBMCs was constructed, which consists of 38 eQTL and 53 pQTL SNPs, 3 miRNAs and 2 DMPs. Besides, RPN2 expression was significantly up-regulated with RA in primary T lymphocytes, as well as in PHA-activated T lymphocytes. RPN2 over-expression in T lymphocytes significantly inhibited apoptosis and IL-4 expression and promoted proliferation and activation. PBMCs-expressed RPN2 mRNA and plasma Rpn2 protein demonstrated superior and modest performances in discriminating RA cases and controls, respectively.

CONCLUSIONS

RPN2 gene influences T lymphocyte growth and activation and is involved in the pathogenesis of RA. Rpn2 may serve as a novel protein biomarker for RA diagnosis.

Recurrent and refractory corneal perforation secondary to rheumatoid arthritis treated with infliximab

Rheumatoid arthritis (RA) can affects many organs including the eyes. Corneal perforation in the form of peripheral ulcerative keratopathy can be debilitating and difficult to manage. A 48-year-old female with known RA presented with sudden loss of vision in her left eye, she was diagnosed with left corneal perforation secondary to severe dry eye. Penetrating keratoplasty (PKP) and punctum occlusion were done. Amniotic membrane transplant (AMT) was done 1 month later due to nonhealing epithelial defect. Her RA was clinically inactive, and no changes in her current medications were made. However, 4 months later, she presented with a second corneal perforation with melting. She had another PKP and AMT with permanent temporal tarsorrhaphy. Cyclosporine 100 mg P. O. twice daily was added, but after 5 months, she presented again with a third left corneal perforation with melting. Again, PKP and AMT with tarsorrhaphy were done, and she was started on infliximab. Since then, she had a stable graft with no further corneal perforations. In summary, patients with RA can have corneal perforations even if other signs of RA are absent. If the systemic treatment that is used to treat RA fails, one should consider using other classes of drugs, such as monoclonal antibodies (e.g., rituximab), tumor necrosis factor alpha blockers (such as infliximab or adalimumab), interleukin (IL)-1 receptor antagonists (e.g., anakinra), or IL-6 receptor antagonist (e.g., tocilizumab).

Beyond the joints, the extra-articular manifestations in rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease typically affecting the joints, but the systemic inflammatory process may involve other tissues and organs. Many extra-articular manifestations are recognized, which are related to worse long outcomes. Rheumatoid nodules are the most common extra-articular feature, found in about 30% of patients. Secondary Sjögren's syndrome and pulmonary manifestations are observed in almost 10% of patients, also in the early disease. Active RA with high disease activity has been associated with an increased risk of such features. Male gender, smoking habit, severe joint disease, worse function, high pro-inflammatory markers levels, high titer of rheumatoid factor, and HLA-related shared epitope have been reported as clinical predictors of occurrence of these rheumatoid complications. In addition, there is a little evidence deriving from randomized controlled trials in this field, thus the therapeutic strategy is mainly empiric and based on small case series and retrospective studies. However, considering that these extra-articular manifestations are usually related to the more active and severe RA, an aggressive therapeutic strategy is usually employed in view of the poor outcomes of these patients. The extra-articular features of RA remain, despite the improvement of joint damage, a major diagnostic and therapeutic challenge, since these are associated with a poor prognosis and need to be early recognized and promptly managed.

Nanoparticle-facilitated delivery of BAFF-R siRNA for B cell intervention and rheumatoid arthritis therapy

The present study was designed to explore the effects of B-cell activating factor receptor (BAFF-R) siRNA encapsulated nanoparticles on collagen-induced arthritis (CIA). BAFF-R siRNA encapsulated nanoparticles (NP-_siBAFF-R) were constructed using a double emulsion method and was characterized by dynamic light scattering and transmission electron microscopy. Cellular uptake of nanoparticles was determined using flow cytometry. The CIA mouse model was established and the mice were intravenously injected with nanoparticles. NP-_siBAFF-R effectively decreased the expression of BAFF-R in B cells and facilitated the delivery of siRNA into B cells. Treatment of NP_siBAFF-R ameliorated rheumatoid arthritis (RA) symptoms in the CIA mouse model via decreasing the arthritis score, mean ankle diameter, the levels of anti-collagen IgG in serum and increasing the expression of collagen type II and osteocalcin in dissected joint tissues. Additionally, treatment of NP_siBAFF-R decreased the percentage and number of B cells and inhibited the production of pro-inflammatory cytokines in RA mice. These results demonstrate that NP-_siBAFF-R may provide an effective strategy for RA treatment.

Effect of nabumetone on humoral immune responses in mice

ABSTRACT Nabumetone is used to reduce the pain and inflammation in rheumatoid arthritis. In the current study, immunomodulatory effect of Nabumetone is investigated in mice. The control group was administered normal saline orally as placebo. Nabumetone was administered orally via gavage in two treatment groups at 14mg/kg.b.w. doses and 28mg/kgb.w., respectively. Haemagglutination (HA) assay, Jerne hemolytic plaque and mice lethality assays were applied. In HA assay, the titer was significantly decreased in Nabumetone treatment groups (P< 0.001). In Jerne hemolytic plaque formation assay, there was a significant reduction (P< 0.001) in number of plaques in Nabumetone treated groups when compared with control. In mice lethality assay, there was a significant difference in mortality ratio of mice in control and Nabumetone treated groups (P< 0.001). Therefore, it is concluded that Nabumetone suppresses the humoral immune response in mice.

Rheumatoid arthritis and systemic lupus erythematosus: Pathophysiological mechanisms related to innate immune system

Rheumatoid arthritis and systemic lupus erythematosus are two highly prevalent autoimmune diseases that generate disability and low quality of life. The innate immune system, a long-forgotten issue in autoimmune diseases, is becoming increasingly important and represents a new focus for the treatment of these entities. This review highlights the role that innate immune system plays in the pathophysiology of rheumatoid arthritis and systemic lupus erythematosus. The role of the innate immune system in rheumatoid arthritis and systemic lupus erythematosus pathophysiology is not only important in early stages but is essential to maintain the immune response and to allow disease progression. In rheumatoid arthritis, genetic and environmental factors are involved in the initial stimulation of the innate immune response in which macrophages are the main participants, as well as fibroblast-like synoviocytes. In systemic lupus erythematosus, all the cells contribute to the inflammatory response, but the complement system is the major effector of the inflammatory process. Detecting alterations in the normal function of these cells, besides its contribution to the understanding of the pathophysiology of autoimmune diseases, could help to establish new treatment strategies for these diseases.

Potential ability for metallothionein and vitamin E protection against cadmium immunotoxicity in head kidney and spleen of grass carp (Ctenopharyngodon idellus)

Cadmium (Cd) pollution is an important issue affecting the food safety of aquatic products. Cd can impair the immune system and cause irreversible damage to fish and other aquatic organisms. The immunoprotection activities of exogenous metallothionein (MT) and vitamin E (VE) were investigated in Cd poisoned grass carp, Ctenopharyngodon idellus, in the present study. C. idellus were divided into three groups: Cd+phosphate-buffered saline (PBS) group; Cd+MT; and Cd+VE. All fish were injected with cadmium chloride (CdCl₂) on the first day and then treated with PBS, MT or VE four days post-injection. Fish not injected with Cd were used as a negative control. Cd exposure caused severe head-kidney and splenic injury in C. idellus, mainly expressed as an increase in Cd content, histological damage, percentage of head-kidney and splenic cells apoptosis and decreases in immune-related gene mRNA transcript expression. However, MT and VE treatments protected against Cd-induced immunotoxicity in C. idellus by decreasing Cd contents, lessening histological damage, reducing the percentage of apoptosis and recovering immune-related mRNA transcript expression. Our results demonstrate that MT and VE can alleviate Cd-induced immunotoxicity and that MT has a more powerful effect than VE, indicating that MT could be a potential antidote in cases of Cd poisoning.

The parasitic worm product ES-62 normalises the gut microbiota bone marrow axis in inflammatory arthritis

The human immune system has evolved in the context of our colonisation by bacteria, viruses, fungi and parasitic helminths. Reflecting this, the rapid eradication of pathogens appears to have resulted in reduced microbiome diversity and generation of chronically activated immune systems, presaging the recent rise of allergic, autoimmune and metabolic disorders. Certainly, gastrointestinal helminths can protect against gut and lung mucosa inflammatory conditions by modulating the microbiome and suppressing the chronic inflammation associated with dysbiosis. Here, we employ ES-62, an immunomodulator secreted by tissue-dwelling Acanthocheilonema viteae to show that helminth-modulation of the gut microbiome does not require live infection with gastrointestinal-based worms nor is protection restricted to mucosal diseases. Specifically, subcutaneous administration of this defined immunomodulator affords protection against joint disease in collagen-induced arthritis, a mouse model of rheumatoid arthritis, which is associated with normalisation of gut microbiota and prevention of loss of intestinal barrier integrity.

Peripheral Ulcerative Keratitis Associated with Autoimmune Disease: Pathogenesis and Treatment

Peripheral ulcerative keratitis (PUK) is type of crescent-shaped inflammatory damage that occurs in the limbal region of the cornea. PUK is always combined with an epithelial defect and the destruction of the peripheral corneal stroma. PUK may have a connection to systemic conditions, such as long-standing rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Wegener granulomatosis (WG), relapsing polychondritis, classic polyarteritis nodosa and its variants, microscopic polyangiitis, and Churg-Strauss syndrome. However, the most common connection is with RA, which is also the focus of this review. The pathogenesis of PUK is still unclear. It is thought that circulating immune complexes and cytokines exert an important influence on the progression of this syndrome. Treatment is applied to inhibit certain aspects of PUK pathogenesis.

Serological markers associated with disease activity in patients with rheumatoid arthritis treated with rituximab

OBJECTIVE

To evaluate prospectively serological markers at baseline and during treatment in patients with rheumatoid arthritis (RA) initiating rituximab treatment, following failure of antitumour necrosis factor (TNF)-α therapy.

METHODS

Patients with RA and healthy control subjects were recruited. Plasma complement (C)3, C4, rheumatoid factor (RF), anticitrullinated protein antibody (ACPA), immunoglobulin (Ig)M, A and G, disease activity scores (DAS) and therapeutic response were recorded at baseline and at 6, 12 and 18 months.

RESULTS

Patients (n = 35) had significantly higher C3 and C4 levels than controls (n = 30). At 12 months after initiation of rituximab, C3 and C4 levels were significantly lower in patients who responded to treatment, compared with nonresponders. There were direct correlations between C3 levels and DAS at 12 months in the study population as a whole, and between IgM levels and DAS in responding patients after 6, 12 and 18 months' treatment.

CONCLUSIONS

C3 and IgM levels may represent potentially useful serological markers of disease activity during rituximab treatment in patients with RA.

Activation of LXR attenuates collagen-induced arthritis via suppressing BLyS production

B-lymphocyte stimulator (BLyS) plays a critical role in the pathogenesis and progression of rheumatoid arthritis (RA). Liver X receptor (LXR), a nuclear receptor, has an important anti-inflammatory effect. However, it is unclear whether the BLyS expression is regulated by LXR. In this study, we found that treatment with LXR agonist in collagen-induced arthritis (CIA) mice significantly attenuated arthritis progression, and markedly decreased BLyS production in serum and splenocytes as well as the production of serum IFNγ and TGFβ. Activation of LXR in B lymphocytes dramatically suppressed the basal and IFNγ/TGFβ-induced BLyS expression. Moreover, LXR agonist prominently suppressed the binding of NF-κB to BLyS promoter region, and decreased the promoter's transcriptional activity. Additionally, activation of LXR obviously repressed IFNγ-induced STAT1 activation and TGFβ-induced SMAD3 activation. These results indicated that downregulation of BLyS may be a novel mechanism by which LXR ameliorates RA, and LXR/BLyS pathway may serve as a novel target for the treatment of RA.

Dysregulation of circulating CD4+CXCR5+ T cells in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by a chronic low-grade inflammatory state. Follicular helper T cells (Tfh) play critical roles in inducing B-cell activation and producing various cytokines, whereas circulating CD4+CXCR5+ T cells (CTfh) may act as a counterpart to measure Tfh cell disorders. In this study, we investigated whether Tfh could be involved in the development of T2DM by assessing CTfh in peripheral blood. CTfh and it subtypes were determined by measuring CD3, CD4, CXCR5, CXCR3, and CCR6 in 68 T2DM patients and 60 healthy controls using flow cytometry. Results showed that proportion of CTfh in the peripheral CD4+ T cells was significantly increased in T2DM patients (8.5 ± 0.5%) than in controls (4.5 ± 0.3%) (p < 0.001). Further study revealed that the balance of CTfh subtypes was greatly dysregulated, in which percentage of Th17 subtype was significantly increased in patients. Investigating the correlation between CTfh and risk factors of T2DM demonstrated that proportion of CTfh were significantly elevated in patients with body mass index (BMI) over 24.0 (p = 0.005). Interestingly, patients with abdominal obesity had further increase in CTfh than those without abdominal obesity. This study suggests the involvement of CTfh in T2DM, especially in T2DM-related obesity.