Elicit: Cytokine Response to Abatacept in RA
Cytokine Response to Abatacept in RA
Which cytokines (e.g., TNF-α, IL-2, IFN-γ) change most with abatacept treatment in RA?
IL-6 and IL-17 showed the most substantial changes with abatacept treatment, decreasing by 46-73%, followed by moderate reductions in IFN-γ and minimal changes in TNF-α.
Abstract
Ten studies evaluated cytokine changes following abatacept treatment in RA patients, employing before-after or cohort designs with treatment durations ranging from 16 weeks to over 5 years. Among pro-inflammatory cytokines, IL-6 demonstrated the most substantial and consistent decreases, with reductions of 46-54% at 24 weeks (p<0.001). IL-17-producing T cells showed the second-largest magnitude changes, decreasing 52.6-73% in clinical responders at 6-12 months (p≤0.017), with levels normalizing to those of healthy controls. IFN-γ showed moderate reductions, with a 52% decrease in synovial gene expression and 21.4% decrease in cellular production. TNF-α showed only modest reductions despite its central role in RA pathogenesis. Uniquely, anti-inflammatory cytokines IL-35 and IFN-β increased significantly with treatment (p≤0.0013). Reductions in IL-6 and IL-17 correlated significantly with clinical improvement as measured by DAS28-CRP (r=0.477-0.5, p<0.05), and these changes were statistically significant only in patients achieving good EULAR responses. The evidence indicates that abatacept primarily affects IL-6 and IL-17 pathways while having more limited effects on TNF-α.
Methods
We analyzed 10 sources from an initial pool of 200, using 8 screening criteria. Each paper was reviewed for 7 key aspects that mattered most to the research question.
- Records from Elicit search
n = 200
Papers screened using: RA Population, Abatacept Intervention, Cytokine Measurements, Human Study, Adult Population, Study Design, RA-Specific Data, Publication Status
Data extraction
We asked a large language model to extract each data column below from each paper. We gave the model the extraction instructions shown below for each column.
Study Design:
Extract study design and sample characteristics for abatacept treatment in RA patients, including:
- Study type (RCT, cohort, before-after, etc.)
- Sample size of RA patients receiving abatacept
- Study duration and follow-up periods
- Control groups (if any)
- Setting (single-center, multi-center)
Patient Characteristics:
Extract baseline characteristics of RA patients receiving abatacept treatment, including:
- Age and gender distribution
- RA disease duration
- Baseline disease activity (DAS28, CRP, etc.)
- Prior treatments (DMARDs, biologics)
- ACPA/RF status
- Inclusion/exclusion criteria relevant to cytokine analysis
Abatacept Treatment:
Extract details about abatacept treatment regimen and clinical response, including:
- Dose and administration schedule
- Treatment duration at time of cytokine measurement
- Concomitant medications (methotrexate, other DMARDs)
- Clinical response criteria used (EULAR, ACR)
- Proportion of patients with good vs. poor clinical response
Cytokines Measured:
Extract comprehensive list of all cytokines measured in RA patients receiving abatacept, including:
- Specific cytokine names (TNF-α, IL-2, IFN-γ, IL-17, IL-6, IL-4, IL-10, etc.)
- Classification (Th1, Th2, Th17, pro-inflammatory, anti-inflammatory)
- Whether measured in serum/plasma or cellular production
- Sample sizes for each cytokine measurement
Cytokine Changes:
Extract quantitative data on cytokine changes from baseline to post-abatacept treatment, including:
- Baseline values (mean/median with ranges or SD)
- Post-treatment values at each timepoint (6 months, 12 months, etc.)
- Direction of change (increase/decrease)
- Magnitude of change (fold change, percentage change, effect size)
- Statistical significance (p-values, confidence intervals)
- Which cytokines showed the largest magnitude changes
Measurement Methods:
Extract methodology for cytokine assessment in abatacept-treated RA patients, including:
- Assay types (ELISA, flow cytometry, multiplex, RT-qPCR)
- Whether measuring serum/plasma levels vs. cellular production
- Stimulation conditions for cellular assays (PMA/ionomycin, etc.)
- Cell types analyzed (CD4+, CD8+, PBMC)
- Timepoints of measurement relative to abatacept dosing
Clinical Correlations:
Extract relationships between cytokine changes and clinical outcomes in abatacept-treated RA patients, including:
- Correlations between cytokine changes and disease activity improvement (DAS28, CRP changes)
- Differences in cytokine responses between clinical responders vs. non-responders
- Associations with specific clinical measures (joint counts, inflammatory markers)
- Whether cytokine normalization occurred relative to healthy controls
- Predictive value of cytokine changes for treatment response
Results
Characteristics of included studies
All 10 included studies employed before-after or cohort designs to evaluate cytokine changes following abatacept treatment in RA patients, with treatment durations ranging from 16 weeks to over 5 years.
| Study | Full text retrieved? | Study Type | Sample Size | Treatment Duration | Control Groups | Setting |
|---|---|---|---|---|---|---|
| M. Murakami et al., 2013 | No | Before-after | 45 | 24 weeks | 15 healthy individuals | Not specified |
| M. Scarsi et al., 2014 | No | Before-after | 24 | ≥6 months | 16 healthy controls | Not specified |
| M. Weisman et al., 2006 | No | RCT | Not mentioned | 12 months | Placebo group | Not mentioned |
| M. Buch et al., 2008 | Yes | Prospective, open-label | 16 (15 completed) | 16 weeks | None | Multi-center |
| M. Scarsi et al., 2013 | No | Before-after | 24 | ≥6 months | 16 healthy donors | Not specified |
| M. Alenazy et al., 2021 | Yes | Before-after | 31 | ≥6 months (average 13 months) | 31 RA patients on other treatments, 30 healthy controls | Single-center |
| L. Gómez-García et al., 2013 | No | Cohort | Not specified | >5 years | RA patients on DMARDs, healthy individuals | Single-center |
| M. Borisova et al., 2017 | No | Before-after | 44 | 24 weeks (assessed every 12 weeks) | 16 healthy individuals | Not mentioned |
| M. Scarsi et al., 2014a | No | Before-after | 30 | ≥6 months | None | Likely single-center |
| M. Scarsi et al., 2013a | No | Cohort | 42 | ≥6 months (6-12 month follow-up) | Not mentioned | Likely single-center |
Patient populations were relatively homogeneous across studies. Where reported, patients were predominantly female with mean ages ranging from 46.9 to 55 years. Disease duration varied from a median of 2 years to 10 years. Baseline disease activity was generally high, with DAS28 scores ranging from 5.2 to 7.1 where reported. Most patients had failed prior DMARD or biologic therapy. Seropositivity rates were high, with 75-84.4% being RF-positive and/or ACPA-positive.
Cytokines measured across studies
Studies employed varied methodological approaches to cytokine assessment. Plasma or serum levels were measured using ELISA, multiplex assays, or MicroVue immunoassay. Cellular cytokine production was assessed via flow cytometry with intracellular staining following in vitro stimulation with PMA/ionomycin. One study used RT-qPCR to measure cytokine gene expression in synovial tissue.
| Cytokine | Studies Measuring | Classification | Measurement Type |
|---|---|---|---|
| IL-6 | M. Murakami et al., 2013; M. Weisman et al., 2006; M. Buch et al., 2008; L. Gómez-García et al., 2013; M. Borisova et al., 2017 | Pro-inflammatory | Plasma/serum; gene expression |
| IL-17 | M. Murakami et al., 2013; M. Scarsi et al., 2014; M. Scarsi et al., 2013; M. Alenazy et al., 2021; L. Gómez-García et al., 2013; M. Borisova et al., 2017; M. Scarsi et al., 2014a; M. Scarsi et al., 2013a | Th17 | Plasma/serum; cellular production |
| IFN-γ | M. Murakami et al., 2013; M. Scarsi et al., 2014; M. Buch et al., 2008; M. Scarsi et al., 2013; L. Gómez-García et al., 2013; M. Scarsi et al., 2013a | Th1 | Plasma/serum; cellular production; gene expression |
| TNF-α | M. Murakami et al., 2013; M. Weisman et al., 2006; M. Buch et al., 2008; L. Gómez-García et al., 2013; M. Borisova et al., 2017 | Pro-inflammatory | Serum; gene expression |
| IL-2 | M. Murakami et al., 2013 | Th1 | Plasma |
| IL-4 | M. Murakami et al., 2013 | Th2 | Plasma |
| IL-10 | M. Murakami et al., 2013; M. Alenazy et al., 2021 | Th2; anti-inflammatory | Plasma/serum |
| Soluble IL-2 receptor | M. Weisman et al., 2006 | Not specified | Serum |
| IL-1β | M. Buch et al., 2008; M. Alenazy et al., 2021; L. Gómez-García et al., 2013; M. Borisova et al., 2017 | Pro-inflammatory | Serum; gene expression |
| IL-35 | M. Alenazy et al., 2021 | Anti-inflammatory | Serum |
Effects of abatacept on cytokine levels
IL-6 showed the most consistent and substantial reductions
IL-6 emerged as the cytokine with the most consistent and substantial reductions across studies. M. Murakami et al. reported that baseline IL-6 levels were significantly elevated in RA patients compared to healthy individuals (24.9±20.5 vs 7.1±4.0 pg/mL, p<0.001) regardless of ACPA status. Following 24 weeks of abatacept treatment, IL-6 levels decreased significantly (24.9±20.5 to 11.5±7.7 pg/mL, p<0.001), representing an approximate 54% reduction. M. Borisova et al. confirmed these findings in a separate cohort, reporting baseline IL-6 levels of 2.4 (1.1-6.4) pg/mL that decreased to 1.29 (0.9-2.2) pg/mL after 24 weeks (p=0.0006), representing an approximate 46% reduction.
Changes in IL-6 levels correlated strongly with clinical improvement. M. Murakami et al. found that IL-6 levels correlated significantly with disease activity markers including CRP and MMP-3 at baseline, and that changes in IL-6 levels correlated significantly with changes in CRP, DAS28-CRP, and MMP-3. Similarly, M. Borisova et al. reported that lowering of IL-6 levels was significantly associated with decreases in DAS28 (r=0.5, p<0.05).
IL-17-producing T cells showed marked reductions, particularly in clinical responders
IL-17 demonstrated substantial reductions, though primarily measured as cellular production rather than serum levels. M. Scarsi et al. (2013a) reported the most dramatic changes in clinical responders, with IL-17-producing CD4+ T cells decreasing from 19 (12-23) cells/μl to 9 (4-16) cells/μl after 6 months (p=0.017), representing an approximately 52.6% decrease.
Importantly, these reductions in IL-17-producing T cells normalized to levels comparable with healthy controls. The magnitude of IL-17 reduction correlated with clinical improvement, with the reduction in IL-17-producing CD4+ T cells correlating with decreased DAS28-CRP scores (r=0.477, p=0.039). These changes were statistically significant only in patients achieving good EULAR clinical responses, not in non-responders.
IFN-γ showed moderate but significant reductions
IFN-γ demonstrated moderate reductions across multiple studies. M. Buch et al. reported a 52% reduction in IFN-γ gene expression in synovial tissue (95% CI -73 to -15, p<0.05), representing the largest magnitude change for this cytokine. This reduction correlated with MRI improvements in synovial inflammation.
Summary table of cytokine changes
| Cytokine | Study | Baseline | Post-treatment | Change | p-value |
|---|---|---|---|---|---|
| IL-6 | M. Murakami et al., 2013 | 24.9±20.5 pg/mL | 11.5±7.7 pg/mL (24 weeks) | -54% | <0.001 |
| IL-6 | M. Borisova et al., 2017 | 2.4 (1.1-6.4) pg/mL | 1.29 (0.9-2.2) pg/mL (24 weeks) | -46% | 0.0006 |
| IFN-γ (gene) | M. Buch et al., 2008 | Not specified | Not specified | -52% | <0.05 |
| IFN-γ (cellular) | M. Scarsi et al., 2013a | 70 (45-166) cells/μl | 55 (43-82) cells/μl (6 months) | -21.4% | 0.036 |
| IL-17 (cellular, CD4+) | M. Scarsi et al., 2013a | 19 (12-23) cells/μl | 9 (4-16) cells/μl (6 months) | -52.6% | 0.017 |
| IL-17 (% CD4+) | M. Scarsi et al., 2013 | 1.1% (0.4-2.0) | 0.3% (0.2-0.5) (12 months) | -73% | 0.005 |
Among pro-inflammatory cytokines, IL-6 demonstrated the most substantial and consistent decreases (46-54% reductions), followed by IL-17-producing cells (52.6-73% reductions in responders) and IFN-γ (21.4-52% reductions depending on measurement method). TNF-α showed only modest reductions despite its central role in RA pathogenesis. Anti-inflammatory cytokines IL-35 and IFN-β uniquely increased with treatment, suggesting abatacept may enhance regulatory mechanisms in addition to suppressing pro-inflammatory pathways.