Exploring complement biomarkers in suspected axial spondyloarthritis.

OBJECTIVES: To investigate lectin pathway proteins (LPPs) as biomarkers for axial spondyloarthritis (axSpA) in a cross-sectional cohort with a suspicion of axSpA, comprising newly diagnosed axSpA and chronic low back pain (cLBP) individuals. METHODS: Serum samples from 515 participants within the OptiRef cohort, including 151 axSpA patients and 364 cLBP patients, were measured using immunoassays for LPPs (mannan-binding lectin (MBL), collectin liver-1 (CL-L1), M-ficolin, H-ficolin and L-ficolin, MBL-associated serine proteases (MASP)-1, -2 and -3, MBL-associated proteins (MAp19 and MAp44) and the complement activation product C3dg). RESULTS: Serum levels of L-ficolin, MASP-2 and C3dg were elevated in axSpA patients, whereas levels of MASP-3 and CL-L1 were decreased, and this remained significant for C3dg and MASP-3 after adjustment for C reactive protein (CRP). A univariate regression analysis showed serum levels of CL-L1, MASP-2, MASP-3 and C3dg to predict the diagnosis of axSpA, and MASP-3 and C3dg remained significant in a multivariate logistic regression analysis. Assessment of the diagnostic potential showed that a combination of human leukocyte antigen B27 (HLA-B27) and measurements of L-ficolin, MASP-3 and C3dg increased the diagnostic specificity for axSpA, however, with a concomitant loss of sensitivity. CONCLUSIONS: Serum levels of complement activation, that is, C3dg, and MASP-3 differed significantly between axSpA and cLBP patients after adjustment for CRP. Although combining HLA-B27 with measurements of L-ficolin, MASP-3 and C3dg increased the diagnostic specificity for axSpA, this seems unjustified due to the concomitant loss of sensitivity. However, both C3dg and MASP-3 were associated with axSpA diagnosis in multivariate logistic regression, suggesting an involvement of complement in the inflammatory processes and possibly pathogenesis in axSpA.

Serum biomarkers and their relationship to axial spondyloarthritis associated with inflammatory bowel diseases.

Spondyloarthritis (SpA) constitute a group of chronic inflammatory immune-mediated rheumatic diseases characterized by genetic, clinical, and radiological features. Recent efforts have concentrated on identifying biomarkers linked to axial SpA associated with inflammatory bowel disease (IBD), offering predictive insights into disease onset, activity, and progression. Genetically, the significance of the HLA-B27 antigen is notably diminished in ankylosing spondylitis (AS) associated with IBD, but is heightened in concurrent sacroiliitis. Similarly, certain polymorphisms of endoplasmic reticulum aminopeptidase (ERAP-1) appear to be involved. Carriage of variant NOD2/CARD15 polymorphisms has been demonstrated to correlate with the risk of subclinical intestinal inflammation in AS. Biomarkers indicative of pro-inflammatory activity, including C-reactive protein (CRP) along with erythrocyte sedimentation rate (ESR), are among the consistent predictive biomarkers of disease progression. Nevertheless, these markers are not without limitations and exhibit relatively low sensitivity. Other promising markers encompass IL-6, serum calprotectin (s-CLP), serum amyloid (SAA), as well as biomarkers regulating bone formation such as metalloproteinase-3 (MMP-3) and Dickkopf-related protein 1 (DKK-1). Additional candidate indicators of structural changes in SpA patients include matrix metalloproteinase-3 (MMP-3), vascular endothelial growth factor (VEGF), tenascin C (TNC), and CD74 IgG. Fecal caprotein (f-CLP) levels over long-term follow-up of AS patients have demonstrated predictive value in anticipating the development of IBD. Serologic antibodies characteristic of IBD (ASCA, ANCA) have also been compared; however, results exhibit variability. In this review, we will focus on biomarkers associated with both axial SpA and idiopathic intestinal inflammation, notably enteropathic spondyloarthritis.

Serum granulocyte-macrophage colony-stimulating factor (GM-CSF) is increased in patients with active radiographic axial spondyloarthritis and persists despite anti-TNF treatment.

BACKGROUND: Accumulating evidence supports the role of monocytes and neutrophils in radiographic axSpA (r-axSpA). Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a growth factor for both leukocyte lineages and a pro-inflammatory cytokine activating myeloid cells and promoting osteoclastogenesis. It acts through the JAK-STAT pathway. We measured serum GM-CSF and markers of bone metabolism in patients with r-axSpA before and after anti-TNF treatment. METHODS: Patients with active r-axSpA despite treatment with NSAIDs, all eligible for treatment with a biologic agent, were recruited. Healthy donors were sampled as controls. Serum was collected before (baseline) and after 4-6 months (follow-up) of anti-TNF treatment and the following molecules were measured with ELISA: GM-CSF, sclerostin (SOST), and dickkopf-1 (Dkk-1). RESULTS: Twelve r-axSpA patients (7 males, 5 females, median age 37 years) with a median disease duration of 1 year and 16 age- and sex-matched controls were included. At baseline, patients had mean BASDAI 6.3±2 and ASDAS 3.2±0.7, which decreased to 4.1±1.7 and 2.2±0.6 at follow-up, respectively. At baseline, r-axSpA patients had significantly higher mean serum levels of GM-CSF (150 vs 62pg/ml, p=0.049), significantly lower Dkk-1 (1228 vs 3052pg/ml, p=0.001), but similar levels of SOST (369 vs 544pg/ml, p=0.144) compared to controls. Anti-TNF treatment did not affect GM-CSF, Dkk-1, or SOST levels. Spearman correlation analysis showed that GM-CSF correlated positively with ASDAS at baseline (r=0.61, p=0.039), while no correlations were identified between bone markers (Dkk-1, SOST) on one hand and GM-CSF or disease activity indices on the other. CONCLUSIONS: GM-CSF is increased in patients with active AS and strongly correlates with disease activity. TNF inhibition does not affect GM-SCF levels, despite improving disease activity. GM-CSF may represent an important pathway responsible for residual inflammation during TNF blockade, but also a potential target of JAK inhibitors, explaining their efficacy in r-axSpA.

The association between elevated serum interleukin-22 and the clinical diagnosis of axial spondyloarthritis: A retrospective study.

OBJECTIVE: There is an unmet need for a reliable biomarker for the differentiation of axial spondyloarthritis (AxSpA) from its mimickers. Serum levels of interleukin-22 (IL-22) have previously been found to be significantly elevated in patients with AxSpA compared with healthy individuals or persons with osteoarthritis. METHODS: Consecutive patients with established or suspected AxSpA were enrolled. The clinical data, as well as results of laboratory and imaging studies, were acquired from patients' charts. The final diagnosis of definite or probable SpA, or an alternative diagnosis, was determined, and the serum levels of IL-22 were examined by enzyme-linked immunosorbent immunoassay. RESULTS: Interleukin-22 levels were significantly higher in patients with definite AxSpA (29 patients) compared with patients with alternative diagnoses (14 patients) and healthy volunteers (16 individuals; P < 0.001 for both comparisons). The sensitivity and specificity of the serum IL-22 for the AxSpA diagnosis were 0.68 (95% CI 0.49-0.84) and 0.86 (95% CI 0.68-0.95), respectively, for the cut-off value of 5 pg/mL. In patients with AxSpA, serum IL-22 levels did not correlate with modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS), or serum C-reactive protein. CONCLUSION: Serum IL-22 levels are elevated in patients with the clinical diagnosis of AxSpA and can potentially serve as an independent biomarker for the differentiation of AxSpA from its non-inflammatory mimickers.

Early control of C-reactive protein levels with non-biologics is associated with slow radiographic progression in radiographic axial spondyloarthritis.

AIM: Predicting radiographic progression is vital for assessing the prognosis of patients with radiographic axial spondyloarthritis, and C-reactive protein (CRP) may be a valuable biomarker for this purpose. This study aimed to investigate the relationship between changes in the CRP level and spinal radiographic progression in patients with radiographic axial spondyloarthritis who were initially treated with non-biologics. METHODS: Patients with radiographic axial spondyloarthritis who were followed up for 18 years at a single center and initially treated with nonsteroidal anti-inflammatory drugs and/or conventional disease-modifying antirheumatic drugs for 3 months were included. Patients with a CRP level of <0.8 mg/dL or 50% of the baseline CRP at 3 months were assigned to the controlled CRP group (n = 351), and the remaining patients were assigned to the uncontrolled CRP group (n = 452). A generalized estimating equation was used to analyze the differences in the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) between the 2 groups. RESULTS: The increase in the mSASSS was slower in the controlled CRP group than in the uncontrolled CRP group (interaction term ß = -.499, 95% confidence interval -0.699 to -0.300). CONCLUSION: Controlled CRP achieved in response to initial treatment with non-biologic agents for 3 months was significantly associated with a slower rate of spinal radiographic change in patients with radiographic axial spondyloarthritis. The CRP level at 3 months after initial non-biologic treatment is a good predictor of radiographic progression.

Correlation between C-Reactive Protein to Albumin Ratio and Disease Activity in Patients with Axial Spondyloarthritis.

BACKGROUND: The C-reactive protein (CRP) to albumin (ALB) ratio (CAR) has emerged as a novel inflammatory biomarker. This study was designed to investigate the role of CAR in the disease activity of axial spondyloarthritis (axSpA). METHODS: A total of 241 patients and 61 healthy controls were retrospectively enrolled in this study. AxSpA patients were further divided into the inactive group (n = 176) and active group (n = 65) according to Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) cutoff value of 4. Laboratory data and clinical assessment indices were recorded. Spearman's correlation analysis, receiver operation characteristic (ROC) curve analysis, and binary logistic regression analysis were performed. RESULTS: In axSpA patients, CAR was significantly higher than the healthy group (P < 0.001). Similarly, axSpA patients in the active group had higher CAR than the inactive group (P < 0.001). Besides, CAR was positively correlated with erythrocyte sedimentation rate (ESR) (r = 0.704, P < 0.001), CRP (r = 0.996, P < 0.001), BASDAI (r = 0.329, P < 0.001), and Bath Ankylosing Spondylitis Functional Index (BASFI) (r = 0.330, P < 0.001). ROC curve analysis suggested that the area under the curve (AUC) of CAR for axSpA of the active group was 0.701, which was higher than that of CRP and ESR. The optimal cutoff point of CAR for axSpA of the active group was 0.3644, with a sensitivity and specificity of 58.5% and 79.0%. Binary logistic analysis results revealed that CAR was an independent predictive factor for axSpA disease activity (odds ratio = 4.673, 95% CI: 1.423-15.348, P = 0.011). CONCLUSIONS: CAR was increased in axSpA and axSpA of the active group. CAR may be a novel and reliable indicator for axSpA disease activity.

Predictive value of anti-CarP and anti-PAD3 antibodies alone or in combination with RF and ACPA for the severity of rheumatoid arthritis.

OBJECTIVES: The objective of this study was to analyse the predictive value of anti-carbamylated protein (anti-CarP) and anti-peptidyl-arginine deiminase type-3 (anti-PAD3) antibodies, alone or in combination with RF and ACPA, to identify patients at high risk of developing severe RA outcomes. METHODS: Patients within the Swiss Clinical Quality Management registry with a biobank sample were tested for RF, ACPA, anti-CarP, and anti-PAD3 antibodies. We examined the association of each autoantibody with DAS28, HAQ and radiographic damage (Ratingen) at baseline and longitudinally. RESULTS: Analyses included 851 established RA patients and 516 disease controls [axial spondyloarthritis (axSpA = 320) and PsA (196)]. Anti-CarP and anti-PAD3 antibodies were, respectively, present in 22.4% and 10.7% of the whole RA population, and in 13.2% and 3.8% of the RF and ACPA double seronegative patients. At baseline, RA patients with anti-PAD3 had higher DAS28 (4.2 vs 3.7; P= 0.005) and significantly more radiographic damage (14.9 vs 8.8; P= 0.02) than anti-PAD3-negative patients. In the ACPA-negative subgroup, baseline Ratingen scores were significantly higher in anti-PAD3-positive patients (P= 0.01). The combination of anti-PAD3, RF IgM, and ACPA was associated with significantly higher baseline radiographic scores than the double seropositive group (P= 0.04). The presence of any two of the previous autoantibodies was associated with significantly greater radiographic progression over 10 years than if all were absent (P= 0.02). There were no differences in RA outcome measures with regards to anti-CarP. CONCLUSIONS: Anti-PAD3 antibodies are associated with higher disease activity and joint damage scores in RA patients.

Neutrophil-to-lymphocyte Ratio, Platelet-to-lymphocyte Ratio, C-reactive Protein to Albumin Ratio, and Albumin to Fibrinogen Ratio in Axial Spondyloarthritis: A Monocentric Study.

BACKGROUND: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are routinely used to assess disease activity in spondyloarthritis. New biomarkers have been reported, such as neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), CRP to albumin ratio (CAR), and albumin to fibrinogen ratio (AFR). AIMS: Our study aimed to assess these ratios in spondyloarthritis and to determine the relationship between these ratios and the disease activity. METHODS: We conducted a cross-sectional study, including patients with spondyloarthritis. The following ratios were calculated: PLR, NLR, AFR, and CAR. Pearson correlation analysis was carried out to test the correlation of the data. Receiver operating characteristic curves were evaluated for each ratio using ASDASCRP as the gold standard for disease activity. RESULTS: Eighty-five patients were included. The sex ratio was 60 males to 25 females. The mean age was 42.58 ± 11.75 years. There was a positive correlation between the PLR and the following parameters: CAR, CRP, and ESR. A negative correlation was found between AFR and the following ratios: PLR, NLR, CRP, and ESR. The ASDAS correlated negatively with AFR and positively with both PLR and CAR. The cutoff values of CAR and PLR to distinguish patients with very high disease activity (ASDASCRP>3.5) were 0.442 and 173.64, respectively. CONCLUSIONS: Given their good correlation with ESR and CRP, we suggest that PLR, CAR, and AFR can be used as potential indicators of inflammation in spondyloarthritis. The CAR and PLR are useful to identify patients with very high disease activity.

Preliminary Report on Interleukin-22, GM-CSF, and IL-17F in the Pathogenesis of Acute Anterior Uveitis.

Purpose:Anterior uveitis is the most common anatomic subset of uveitis. We developed a novel multi-parametric flow cytometry panel to identify immune dysregulation signatures in HLA B27-associated acute anterior uveitis (AAU) and axial spondyloarthritis (AxSpA).Methods: We used fluorescence activated cell sorting to characterize T cell cytokine expression in stimulated T cell subsets from patients with AAU (n = 4) compared to healthy controls (n = 14) or subjects with AxSpA (n = 6).Results: Positive findings among subjects with AAU included a statistically significant increase in stimulated granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, and IL-22 synthesized by CD8 cells, a trend for stimulated ILC (innate lymphoid cells)-3 cells to synthesize more IL-22 (p = .07), and stimulated MAIT (mucosa associated innate lymphoid cells)-like cells that express the T cell receptor V alpha 7.2 to express IL-17A, IL-17F, and IL-22 in a greater percentage of cells relative to controls. IL-17F, GM- CSF, and IL-22 represent potentially novel targets in AAU.Conclusion: Our report is arguably the first to implicate IL-17F or ILC-3 and MAIT cells in the pathogenesis of AAU.Abbreviations AAU: acute anterior uveitis; AxSpA: axial spondyloarthritis; BASDAI: Bath ankylosing spondylitis disease activity index; CCR: chemokine receptor; DMSO: dimethylsulfoxide; EULAR:European League Against Rheumatism; FACS: fluorescence activated cell sorter; FBS: fetal bovine serum; FSC: orward light scatter; GM-CSF: granulocyte-macrophage colony stimulating factor; HC: healthy control; ILC: innate lymphoid cell; KIR: killer immunoglobulin receptor; MAIT: mucosal associated immune T cell; ND: not detected; NK: natural killer cell; OHSU-Oregon Health & Science University; PBMC: peripheral blood mononuclear cell; SSC: side light scatter; TCR: T cell receptor.