Changes in agalactosyl IgG levels correlate with radiological progression in early rheumatoid arthritis

Interactions between systemic diseases and oral microbiota shifts in the aging community: A narrative review

As a gateway to general health and a diverse microbial habitat, the oral cavity is colonized by numerous microorganisms such as bacteria, fungi, viruses, and archaea. Oral microbiota plays an essential role in preserving oral health. Besides, the oral cavity also significantly contributes to systemic health. Physiological aging influences all body systems, including the oral microbial inhabitants. The cited effect can cause diseases by forming dysbiotic communities. Since it has been demonstrated that microbial dysbiosis could disturb the symbiosis state between the host and the resident microorganism, shifting the condition toward a more pathogenic one, this study investigated how the oral microbial shifts in aging could associate with the development or progression of systemic diseases in older adults. The current study focused on the interactions between variations in the oral microbiome and prevalent diseases in older adults, including diabetes mellitus, Sjögren's syndrome, rheumatoid arthritis, pulmonary diseases, cardiovascular diseases, oral candidiasis, Parkinson's disease, Alzheimer's disease, and glaucoma. Underlying diseases can dynamically modify the oral ecology and the composition of its resident oral microbiome. Clinical, experimental, and epidemiological research suggests the associations of systemic disorders with bacteremia and inflammation after oral microbial changes in older adults.

The Role of B Cell and T Cell Glycosylation in Systemic Lupus Erythematosus

Glycosylation is a post-translational modification that affects the stability, structure, antigenicity and charge of proteins. In the immune system, glycosylation is involved in the regulation of ligand-receptor interactions, such as in B-cell and T-cell activating receptors. Alterations in glycosylation have been described in several autoimmune diseases, such as systemic lupus erythematosus (SLE), in which alterations have been found mainly in the glycosylation of B lymphocytes, T lymphocytes and immunoglobulins. In immunoglobulin G of lupus patients, a decrease in galactosylation, sialylation, and nucleotide fucose, as well as an increase in the N-acetylglucosamine bisector, are observed. These changes in glycoisolation affect the interactions of immunoglobulins with Fc receptors and are associated with pericarditis, proteinuria, nephritis, and the presence of antinuclear antibodies. In T cells, alterations have been described in the glycosylation of receptors involved in activation, such as the T cell receptor; these changes affect the affinity with their ligands and modulate the binding to endogenous lectins such as galectins. In T cells from lupus patients, a decrease in galectin 1 binding is observed, which could favor activation and reduce apoptosis. Furthermore, these alterations in glycosylation correlate with disease activity and clinical manifestations, and thus have potential use as biomarkers. In this review, we summarize findings on glycosylation alterations in SLE and how they relate to immune system defects and their clinical manifestations.

Host and bacterial factors linking periodontitis and rheumatoid arthritis

Observations from numerous clinical, epidemiological and serological studies link periodontitis with severity and progression of rheumatoid arthritis. The strong association is observed despite totally different aetiology of these two diseases, periodontitis being driven by dysbiotic microbial flora on the tooth surface below the gum line, while rheumatoid arthritis being the autoimmune disease powered by anti-citrullinated protein antibodies (ACPAs). Here we discuss genetic and environmental risk factors underlying development of both diseases with special emphasis on bacteria implicated in pathogenicity of periodontitis. Individual periodontal pathogens and their virulence factors are argued as potentially contributing to putative causative link between periodontal infection and initiation of a chain of events leading to breakdown of immunotolerance and development of ACPAs. In this respect peptidylarginine deiminase, an enzyme unique among prokaryotes for Porphyromonas gingivalis, is elaborated as a potential mechanistic link between this major periodontal pathogen and initiation of rheumatoid arthritis development.

Immunoglobulin G N-glycan Biomarkers for Autoimmune Diseases: Current State and a Glycoinformatics Perspective

The effective treatment of autoimmune disorders can greatly benefit from disease-specific biomarkers that are functionally involved in immune system regulation and can be collected through minimally invasive procedures. In this regard, human serum IgG N-glycans are promising for uncovering disease predisposition and monitoring progression, and for the identification of specific molecular targets for advanced therapies. In particular, the IgG N-glycome in diseased tissues is considered to be disease-dependent; thus, specific glycan structures may be involved in the pathophysiology of autoimmune diseases. This study provides a critical overview of the literature on human IgG N-glycomics, with a focus on the identification of disease-specific glycan alterations. In order to expedite the establishment of clinically-relevant N-glycan biomarkers, the employment of advanced computational tools for the interpretation of clinical data and their relationship with the underlying molecular mechanisms may be critical. Glycoinformatics tools, including artificial intelligence and systems glycobiology approaches, are reviewed for their potential to provide insight into patient stratification and disease etiology. Challenges in the integration of such glycoinformatics approaches in N-glycan biomarker research are critically discussed.

Glycosylation in Autoimmune Diseases

Autoimmune diseases are accompanied by changes in protein glycosylation, in both the immune system and target tissues. The best-studied alteration in autoimmunity is agalactosylation of immunoglobulin G (IgG), characterized primarily in rheumatoid arthritis (RA), and then detected also in systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), and multiple sclerosis (MS). The rebuilding of IgG N-glycans in RA correlates with the relapses and remissions of the disease, is associated with physiological states such as pregnancy but also depends on applied anti-inflammatory therapy. In turn, a decreased core fucosylation of the whole pool of IgG N-glycans is a serum glycomarker in autoimmune thyroid diseases (AITD) encompassing Hashimoto's thyroiditis (HT) and Grave's disease (GD). However, fucosylation of anti-thyroglobulin IgG (an immunological marker of HT) was elevated in HT serum. Core fucosylation of IgG oligosaccharides was also lowered in MS and SLE. In AITD and IBD, chronic inflammation T lymphocytes showed the reduced expression of MGAT5 gene encoding β1,6-N-acetylglucosaminyltransferase V (GnT-V) responsible for β1,6-branching of N-glycans, which is important for T cell receptor activation. Structural changes of glycans have a profound effect on the pro-inflammatory activity of immune cells and serum immune proteins, including IgG in autoimmunity.

Rheumatoid Arthritis in the View of Osteoimmunology

Rheumatoid arthritis is characterized by synovial inflammation and irreversible bone erosions, both highlighting the immense reciprocal relationship between the immune and bone systems, designed osteoimmunology two decades ago. Osteoclast-mediated resorption at the interface between synovium and bone is responsible for the articular bone erosions. The main triggers of this local bone resorption are autoantibodies directed against citrullinated proteins, as well as pro-inflammatory cytokines and the receptor activator of nuclear factor-κB ligand, that regulate both the formation and activity of the osteoclast, as well as immune cell functions. In addition, local bone loss is due to the suppression of osteoblast-mediated bone formation and repair by inflammatory cytokines. Similarly, inflammation affects systemic bone remodeling in rheumatoid arthritis with the net increase in bone resorption, leading to systemic osteoporosis. This review summarizes the substantial progress that has been made in understanding the pathophysiology of systemic and local bone loss in rheumatoid arthritis.

Variations in oral microbiome profiles in rheumatoid arthritis and osteoarthritis with potential biomarkers for arthritis screening

The key to arthritis management is early diagnosis and treatment to prevent further joint destruction and maximize functional ability. Osteoarthritis (OA) and rheumatoid arthritis (RA) are two common types of arthritis that the primary care provider must differentiate, in terms of diagnosis and treatment. Effective and non-invasive strategies for early detection and disease identification are sorely needed. Growing evidence suggests that RA has a correlation with oral microbiome and may be affected by its dynamic variations. There is already a study comparing oral microbiome in patients with RA and OA, however, it did not screen for potential biomarkers for arthritis. In this study, we assessed the oral microbiome in saliva samples from 110 RA patients, 67 OA patients and 155 healthy subjects, using 16S rRNA gene amplicon sequencing. The structure and differences in oral microbiome between RA, OA and healthy subjects were analyzed. Eight oral bacterial biomarkers were identified to differentiate RA from OA. This report provides proof of oral microbiota as an informative source for discovering non-invasive biomarkers for arthritis screening.

Anti-citrullinated protein antibodies acquire a pro-inflammatory Fc glycosylation phenotype prior to the onset of rheumatoid arthritis

OBJECTIVE

To determine whether anticitrullinated protein antibodies (ACPA) exhibit specific changes in Fc glycosylation prior to the onset of arthritis.

METHODS

Serum samples of patients with ACPA-positive arthralgia (n=183) were collected at baseline and at various time points of follow-up. 105 patients developed arthritis after a median of 12 months (IQR 6-24) and were classified as having either rheumatoid arthritis (RA, n=48) or undifferentiated arthritis (UA, n=57) based on the 1987 American College of Rheumatology (ACR) criteria. ACPA and total serum IgG were isolated by affinity purification and cleaved by trypsin. ACPA-IgG1 Fc-glycopeptides were subsequently analysed by nano-liquid chromatography mass spectrometry and compared to those of total IgG1.

RESULTS

At baseline, ACPA-IgG1 and total IgG1 from arthralgia patients displayed similar Fc glycosylation patterns. By contrast, at the onset of arthritis, ACPA exhibited a decrease in galactose residues in RA patients, but not in UA patients. This decrease occurred around 3 months prior to diagnosis and was paralleled by an increase in systemic inflammation (erythrocyte sedimentation rate). Galactosylation of total IgG1 was also decreased in RA, but this did not precede the onset of arthritis. Interestingly, we additionally noted a higher degree of ACPA-IgG1 Fc core fucosylation at baseline as compared with total IgG1, which further increased prior to diagnosis.

CONCLUSIONS

ACPA display significant changes in Fc galactosylation and fucosylation prior to the onset of RA. These changes towards a more pro-inflammatory phenotype could be involved in driving the disease process.

IgG glycosylation changes and MBL2 polymorphisms: associations with markers of systemic inflammation and joint destruction in rheumatoid arthritis

OBJECTIVE

To examine whether IgG glycosylation changes and MBL2 genotypes are associated with systemic inflammation and joint destruction in rheumatoid arthritis (RA).

METHODS

IgG N-glycan content was determined from serum in 118 patients with RA by high-throughput glycan analysis using normal-phase high-pressure liquid chromatography. MBL2 extended genotypes (YA/YA, YA/XA, XA/XA, YA/YO, XA/YO, YO/YO) were determined. Systemic inflammation was assessed by serum levels of C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α). Joint destruction was assessed by total Sharp score (TSS) and alloplastic surgery records.

RESULTS

IgG hypogalactosylation was significantly correlated to IL-6 (Spearman's rho = 0.32, p < 0.001), CRP (Spearman's rho = 0.31, p < 0.001), TSS (Spearman's rho = 0.25, p = 0.01), and alloplastic replacement of joints (Spearman's rho = 0.18, p = 0.05). In multivariate analysis including age, CRP, anticitrullinated protein antibodies (ACPA), and other confounders, IgG hypogalactosylation was significantly associated with TSS (p = 0.014) and alloplastic joint replacement (OR 76.5, p = 0.041) in patients homozygous for the high expression MBL2 genotype YA/YA, but not in carriers of lower expression genotypes.

CONCLUSION

Decreased galactosylation of IgG correlated to markers of inflammation, i.e., IL-6 and CRP. Only in patients homozygous for high expression of the MBL2 genotype YA/YA was IgG hypogalactosylation associated with markers of joint destruction. Our results suggest that inflammation-associated decreased galactosylation of IgG combined with high expression MBL2 genotypes are involved in the pathophysiology of RA.

The association between rheumatoid arthritis and periodontal disease

Chronic, plaque-associated inflammation of the gingiva and the periodontium are among the most common oral diseases. Periodontitis (PD) is characterized by the inflammatory destruction of the periodontal attachment and alveolar bone, and its clinical appearance can be influenced by congenital as well as acquired factors. The existence of a rheumatic or other inflammatory systemic disease may promote PD in both its emergence and progress. However, there is evidence that PD maintains systemic diseases. Nevertheless, many mechanisms in the pathogenesis have not yet been examined sufficiently, so that a final explanatory model is still under discussion, and we hereby present arguments in favor of this. In this review, we also discuss in detail the fact that oral bacterial infections and inflammation seem to be linked directly to the etiopathogenesis of rheumatoid arthritis (RA). There are findings that support the hypothesis that oral infections play a role in RA pathogenesis. Of special importance are the impact of periodontal pathogens, such as Porphyromonas gingivalis on citrullination, and the association of PD in RA patients with seropositivity toward rheumatoid factor and the anti-cyclic citrullinated peptide antibody.

[Pathogenesis of parodontitis in rheumatic diseases]

Inflammatory periodontal disease (PD) is a common disease worldwide that has a primarily bacterial aetiology and is characterized by dysregulation of the host inflammatory response. The degree of inflammation varies among individuals with PD independently of the degree of bacterial infection, suggesting that alteration of the immune function may substantially contribute to its extent. Factors such as smoking, education, and body mass index (BMI) are discussed as potential risk factors for PD. Most PD patients respond to bacterial invaders by mobilizing their defensive cells and releasing cytokines such as interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, and IL-6, which ultimately causes tissue destruction by stimulating the production of collagenolytic enzymes, such matrix metalloproteinases. Recently, there has been growing evidence suggesting an association between PD and the increased risk of systemic diseases, such ateriosclerosis, diabetes mellitus, stroke, and rheumatoid arthritis (RA). PD and rheumatologic diseases such as RA share many pathological aspects and immunological findings.

Rheumatoid arthritis is linked to oral bacteria: etiological association

The purpose of this review is to evaluate the association between rheumatoid arthritis (RA) and periodontopathic bacteria. Clinical studies of RA and periodontal disease have provided evidence for a significant association between the two disorders. Patients with long-standing active RA have a substantially increased frequency of periodontal disease compared with that among healthy subjects. High levels of oral anaerobic bacterial antibodies have been found in the serum and synovial fluid of RA patients. Porphyromonas gingivalis, Tannerella forsythensis, and Prevotella intermedia have been identified in RA synovial fluid. Ornidazole, levofloxacin, and clarithromycin are used in the treatment of infections caused by anaerobic bacteria. These antibiotics have been shown to be effective against RA. The evidence in this review indicates that oral bacteria directly associate with etiopathogenesis of RA.

Levofloxacin treatment in patients with rheumatoid arthritis receiving methotrexate

BACKGROUND

Sulfasalazine and tetracyclines are effective against rheumatoid arthritis (RA). Levofloxacin, the bacteriologically active isomer of ofloxacin, is used in the treatment of infections caused by periodontopathic bacteria and facultative anaerobic bacteria. The aim of this study is to evaluate the clinical efficacy, safety, and tolerability of levofloxacin in patients with rheumatoid arthritis.

METHODS

In a 6-month, double-blind trial, we randomly assigned 76 patients with persistently active rheumatoid arthritis despite at least 6 months of methotrexate therapy at a stable dose of 15 to 25 mg per week to receive either levofloxacin (500 mg) or placebo orally once daily while continuing to receive methotrexate. The change from baseline to six months in the swollen-joint count and tender-joint count was the primary measure of efficacy. Secondary endpoints included pain, quality of life, duration of morning stiffness, erythrocyte sedimentation rate, C-reactive protein level, and physician's and patient's global assessments. The data were also analyzed to determine the number of patients meeting American College of Rheumatology criteria for 20, 50, and 70% improvement.

RESULTS

The levofloxacin plus methotrexate was associated with the greatest reduction in the number of swollen or tender joints (P < 0.001). The levofloxacin plus methotrexate group also had significant improvement in many of the secondary outcome measures (P < 0.001). Levofloxacin was well tolerated. There were no dose-limiting toxic effects.

CONCLUSION

In patients with active rheumatoid arthritis who received methotrexate, treatment with levofloxacin significantly improved the signs and symptoms of rheumatoid arthritis.

The changes in monosaccharide composition of immunoglobulin G in the course of rheumatoid arthritis

The objective of this study was to determine whether galactosylation of immunoglobulin G (IgG) in patients with rheumatoid arthritis (RA) correlates with severity and duration of illness. Serum IgG glycosylation from 50 patients with RA in comparison with 30 healthy controls was analyzed. IgG from sera was isolated and monosaccharide composition was determined by means of gas chromatography. Ratio of galactose to mannose content was calculated. Patients were divided into groups according to three different criteria: disease duration, severity of RA (disease activity score index), and radiological degree of advancement of illness according to Steinbrocker. In patients with RA, significant decrease (p<0,01) of galactose ratio was observed in comparison with healthy control. In patients with long duration of RA (more than 15 years), significant decrease of galactose (p<0.05) ratio in comparison with patients who have had arthritis for less then 5 years was observed. For the group of patients with severe RA, we found reduction of galactose (p<0.001) ratio vs the group of patients in remission. For those patients who had radiological stage IV according to Steinbrocker, IgG galactose (p<0.01) content per oligosaccharide chain were also more decreased than in those patients who had stage I RA. Decreased galactosylation and of IgG in RA was observed. The lack of this carbohydrate component of IgG correlates with severity and duration of RA and could be used in monitoring the progression in early arthritis.

Fucosylation of IgG heavy chains is increased in rheumatoid arthritis

OBJECTIVES

Glycosylation of IgG was suggested to be important in the etiology of rheumatoid diseases. Most studies addressed the amount of galactose, but recently we showed that fucose is highly increased in the juvenile chronic arthritis. The objective of this study was to determine fucosylation of IgG heavy chains in patients with rheumatoid arthritis (RA).

DESIGN AND METHODS

IgG was purified from sera of 29 RA patients and 17 matching controls using ammonium sulfate precipitation and ion exchange. Heavy chains were separated by denaturing polyacrylamide gel electrophoresis and their fucosylation analysed using fucose-specific UEA I lectin.

RESULTS

Fucose was found to be approximately 40% increased in RA patients with very high statistical significance (p = 0.00095).

CONCLUSIONS

Fucose on IgG heavy chains is significantly increased in patients with rheumatoid arthritis.

Fucosylation and galactosylation of IgG heavy chains differ between acute and remission phases of juvenile chronic arthritis

Oligosaccharide structures are attached to nearly all membrane and serum proteins, and their composition changes significantly in many diseases. We have analysed glycosylation of IgG heavy chains in 34 patients with juvenile chronic arthritis and 13 control individuals. IgG was purified from 0.7 ml of serum, separated by electrophoresis and transferred on to polyvinylidene difluoride (PVDF) membrane. Ricinus communis agglutinin (RCA I) and Bandeirea simplicifolia (BSA II) and Ulex europaeus (UEA I) lectins were used to measure galactose, N-acetylglucosamine and fucose, respectively. While there was no significant difference in average levels of galactose and N-acetylglucosamine, patients with juvenile chronic arthritis had 2.4 times more fucose attached to IgG heavy chains than control individuals. A different picture emerged when patients were divided into those with acute disease and those in remission. Patients in whom juvenile chronic arthritis was currently active had significantly lower levels of galactose than those in remission, in whom galactose levels were comparable to the control group. Fucose levels in both groups of patients were significantly higher than in the control group. These results show that whereas de-galactosylation is a good test to detect and measure the activity of juvenile chronic arthritis, increased fucosylation is a much more reliable measure for diagnosis of the disease itself.