Fatigue is cross-sectionally not associated with objective assessments of inflammation, but changes in fatigue are associated with changes of disease activity assessments during biologic treatment of patients with established rheumatoid arthritis

Mitochondrial dysfunction and fatigue in Sjögren's disease

OBJECTIVE

Sjögren's disease (SjD) is a chronic exocrine disorder typified by inflammation and dryness, but also profound fatigue, suggesting a pathological basis in cellular bioenergetics. In healthy states, dysfunctional mitochondria are recycled by mitophagic processes; when impaired, poorly functioning mitochondria persist and produce inflammatory reactive oxygen species. Employing a case-control study, we tested our hypothesis that mitochondrial dysregulation in T cells is associated with fatigue in SjD.

METHODS

We isolated pan T cells from peripheral blood mononuclear cells of 13 SjD and 4 non-Sjögren's sicca (NSS) subjects, who completed several fatigue questionnaires, along with 8 healthy subjects. Using Seahorse, we analysed T cells for mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate, which we assessed for correlation with fatigue measures. Using public microarray data available for 190 SjD and 32 healthy subjects, we identified a mitophagic transcriptional signature that stratified SjD patients into 5 discrete clusters. Comparisons between the SjD subjects in these clusters to healthy individuals identified differentially expressed transcripts, which we subjected to bioinformatic interrogation.

RESULTS

Basal OCR, ATP-linked respiration, maximal respiration and reserve capacity were significantly lower in SjD and NSS subjects compared with healthy individuals, with no differences in non-mitochondrial respiration, basal glycolysis or glycolytic reserve. Scores related to a sleep questionnaire and Bowman's Profile of Fatigue and Discomfort showed correlation with altered OCR in SjD. Subgroup differential expression analysis revealed dynamic transcriptional activity between mitophagy subgroups, expanding the number of differentially expressed transcripts tenfold.

CONCLUSIONS

Mitochondrial dysfunction and fatigue are significant problems in SjD warranting further investigation.

The potential role of fatigue in difficult-to-treat rheumatoid arthritis

OBJECTIVES

A subset of patients with rheumatoid arthritis (RA) who remains symptomatic after failing to multiple drugs are deemed to have "difficult-to-treat RA" (D2T RA). Fatigue is a burdensome symptom for RA patients, hindering their improvement. Our purpose was to evaluate the role of fatigue in D2T RA.

METHODS

This cross-sectional study included rheumatoid arthritis (RA) patients between 2018 and 2022, treated with biological agents or targeted synthetic disease-modifying antirheumatic drugs. D2T RA was defined attending EULAR criteria. Independent variable was fatigue (dimensions and impact) assessed by the Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire and Numerical Rating Scales. Covariables: sociodemographic, clinical and treatment. To identify factors independently associated to D2T RA, multivariable logistic regression was run.

RESULTS

The study included 145 patients and 38 (26.21%) developed D2T RA. D2T RA group were older, with more comorbidity and disability. D2T RA patients scored higher for global fatigue (p = 0.003), and almost for all their dimensions except for cognitive fatigue (p = 0.06) and fatigue coping (p = 0.07). Females with D2T RA showed more fatigue than those with non-D2T RA. In the adjusted models, all fatigue dimensions were associated with D2T RA: global fatigue RA (OR: 1.03; p = 0.007), physical (OR: 1.09; p = 0.008), living (OR: 1.09; p = 0.016), cognitive (OR: 1.1; p = 0.046) and emotional (OR: 1.18; p = 0.012).

CONCLUSIONS

Despite the absence of an explicit mention of fatigue in the definition of D2T RA, it appears to be associated to this outcome. Fatigue should be evaluated in a multidimensional perspective, and gender-specific differences should be considered.

Mitochondrial Dysfunction and Fatigue in Sjögren's Disease

Objectives

Sjögren's disease (SjD) is a common exocrine disorder typified by chronic inflammation and dryness, but also profound fatigue, suggesting a pathological basis in cellular bioenergetics. In healthy states, damaged or dysfunctional mitochondrial components are broken down and recycled by mitophagy, a specialized form of autophagy. In many autoimmune disorders, however, evidence suggests that dysfunctional mitophagy allows poorly functioning mitochondria to persist and contribute to a cellular milieu with elevated reactive oxygen species. We hypothesized that mitophagic processes are dysregulated in SjD and that dysfunctional mitochondria contribute to overall fatigue. We sought to link fatigue with mitochondrial dysfunction directly in SjD, heretofore unexamined, and further sought to assess the pathogenic extent and implications of dysregulated mitophagy in SjD.

Methods

We isolated pan T cells via negative selection from the peripheral blood mononuclear cells of 17 SjD and 8 age-matched healthy subjects, all of whom completed fatigue questionnaires prior to phlebotomy. Isolated T cells were analyzed for mitochondrial oxygen consumption rate (OCR) and glycolysis using Seahorse, and linear correlations with fatigue measures were assessed. A mitophagy transcriptional signature in SjD was identified by reanalysis of whole-blood microarray data from 190 SjD and 32 healthy subjects. Differential expression analyses were performed by case/control and subgroup analyses comparing SjD patients by mitophagy transcriptional cluster against healthy subjects followed by bioinformatic interpretation using gene set enrichment analysis.

Results

Basal OCR, ATP-linked respiration, maximal respiration, and reserve capacity were significantly lower in SjD compared to healthy subjects with no observed differences in non-mitochondrial respiration, basal glycolysis, or glycolytic stress. SjD lymphocytic mitochondria show structural alterations compared to healthy subjects. Fatigue scores related to pain/discomfort in SjD correlated with the altered OCR. Results from subgroup analyses by mitophagic SjD clusters revealed highly variable inter-cluster differentially expressed genes (DEGs) and expanded the number of SjD-associated gene targets by tenfold within the same dataset.

Conclusion

Mitochondrial dysfunction, associated with fatigue, is a significant problem in SjD and warrants further investigation.

Pain catastrophizing in rheumatic diseases: prevalence, origin, and implications

Pain is a crucial factor in rheumatic disorders, and reducing it is a primary goal of successful treatment. Adaptive pain-coping strategies can enhance this improvement, but maladaptive approaches such as pain catastrophizing may worsen overall patient well-being. This narrative review aims to provide a concise overview of the existing knowledge on pain catastrophizing in the most prevalent specific rheumatic disorders. The objective of this study was to improve understanding of this phenomenon and its implications, as well as to pinpoint potential directions for future research. We conducted searches in the MEDLINE/PubMed, SCOPUS, and DOAJ bibliography databases to identify articles related to pain catastrophizing in rheumatoid arthritis, psoriatic arthritis, axial spondylarthritis, systemic sclerosis, systemic lupus erythematosus, Sjögren's syndrome, juvenile idiopathic arthritis, and osteoarthritis (non-surgical treatment). Data extraction was performed on November 1, 2023. The investigators screened the identified articles to determine their relevance and whether they met the inclusion criteria. Following a bibliography search, which was further expanded by screening of citations and references, we included 156 records in the current review. The full-text analysis centred on pain catastrophizing, encompassing its prevalence, pathogenesis, and impact. The review established the role of catastrophizing in amplifying pain and diminishing various aspects of general well-being. Also, potential treatment approaches were discussed and summarised across the examined disorders. Pain catastrophizing is as a significant factor in rheumatic disorders. Its impact warrants further exploration through prospective controlled trials to enhance global patient outcomes.

Relative Impact of Pain and Disease Activity on Improvements in Fatigue: Results From 2 Baricitinib Phase 3 Clinical Trials

BACKGROUND/OBJECTIVE

Fatigue is common in patients with rheumatoid arthritis (RA). We assessed the relative impact of pain and disease activity on improvements in fatigue in 2 phase 3 baricitinib clinical trials.

METHODS

RA-BEAM (NCT01710358) and RA-BEACON (NCT01721044) were randomized, double-blind, placebo-controlled studies in adults with moderate to severe RA. RA-BEAM assessed baricitinib + methotrexate (MTX) and adalimumab + MTX in patients with prior inadequate response/intolerance (IR) to MTX (MTX-IR). RA-BEACON assessed patients with IR to ≥1 biologic disease-modifying antirheumatic drug (bDMARD-IR). Measures included the Functional Assessment of Chronic Illness Therapy-Fatigue scale, Clinical Disease Activity Index (CDAI) for RA, and pain visual analog scale (VAS). Analyses were implemented separately for each study.

RESULTS

Significant improvements were seen in disease activity and pain, which were greater with baricitinib versus adalimumab. A statistically significant improvement was seen in fatigue with both active treatments versus placebo. Moderate correlations were observed between improvements in disease activity and fatigue and between improvements in pain and fatigue in both MTX-IR and bDMARD-IR patients. Reductions in pain (≥50%) and remission or low disease activity (CDAI ≤10) had significant associations with fatigue improvement at week 24. In mediation analysis, improvements in fatigue attributable to CDAI and pain VAS in MTX-IR patients were 31% and 52%, respectively, for baricitinib, and 30% and 47%, respectively, for adalimumab. In bDMARD-IR patients, improvement in fatigue was attributed 48% to CDAI and 48% to pain VAS.

CONCLUSIONS

In both MTX-IR and bDMARD-IR patients, a large proportion of improvements in fatigue across treatment arms were accounted for by improvements in pain and disease activity.

Fatigue in patients with early rheumatoid arthritis undergoing treat-to-target therapy: predictors and response to treatment

OBJECTIVES

Fatigue is a frequent symptom in rheumatoid arthritis (RA) and has high impact on quality of life. We explored associations between disease activity and fatigue in patients with early RA during the initial 24 months of modern treat-to-target therapy and predictors of fatigue after 24 months of follow-up.

METHODS

Data were obtained from the treat-to-target, tight control Aiming for Remission in Rheumatoid Arthritis: a Randomised Trial Examining the Benefit of Ultrasound in a Clinical Tight Control Regime (ARCTIC) trial. Fatigue was measured on a visual analogue scale (VAS) from 0 to 100 mm and defined as clinically relevant if VAS was ≥20 mm. Baseline predictors of fatigue at 24 months were analysed by multivariable logistic regression.

RESULTS

205 patients with fatigue data at baseline and 24 months were included. Median (25th, 75th percentiles) symptom duration was 5.4 months (2.8, 10.4), fatigue VAS 37.0 mm (13.0, 62.0) and mean Disease Activity Score (DAS) 3.4 (SD 1.1) at baseline. Prevalence of fatigue declined from 69% at baseline to 38% at 24 months. Fewer swollen joints (OR 0.92, 95% CI 0.87 to 0.98, p=0.006), lower power Doppler ultrasound score (OR 0.95, 95% CI 0.90 to 0.99, p=0.027) and higher patient global assessment (PGA) (OR 1.03, 95% CI 1.01 to 1.04, p<0.001) increased the risk of clinically relevant fatigue at 24 months. Not achieving remission at 6 months was associated with a higher risk of reporting fatigue at 24 months.

CONCLUSIONS

Fatigue in patients with early RA was prevalent at disease onset, with a rapid and sustained reduction during treatment. Low objective disease activity and high PGA at baseline were predictors of clinically relevant fatigue at 24 months.

Fatigue Is Not Associated With Objective Assessments of Inflammation During Tocilizumab Treatment of Patients With Rheumatoid Arthritis

Objective

In patients with rheumatoid arthritis (RA), the relation between fatigue and disease activity is not established, and our objective was to explore in post hoc analyses the associations between fatigue and subjective as well as objective assessments of inflammation during follow‐up of patients with RA initiating biologic treatment.

Methods

In a Nordic multicenter study, patients with RA starting tocilizumab were examined for fatigue (Functional Assessment of Chronic Illness Therapy–Fatigue sum score) as well as patient‐reported outcome measures (PROMs) (patient's global disease activity, joint pain, and Health Assessment Questionnaire Disability Index), clinical examinations (examiner's global disease activity, 28 tender/swollen joint counts), laboratory variables (erythrocyte sedimentation rate, C‐reactive protein), and ultrasound assessments (semiquantitative scoring [0‐3]) of gray scale and Doppler of 36 joints and 4 tendons) at baseline and 4, 12, and 24 weeks. The associations were explored by using nonparametric tests, including the Wilcoxon rank test, the Mann–Whitney U test, Spearman correlations, and a linear regression and linear mixed model.

Results

One hundred ten patients were included (83% female, mean [SD] age 55.6 [12.1] years, mean [SD] RA duration 8.7 [9.5] years, 81% anti–cyclic citrullinated peptide positive). Fatigue, PROMs, and clinical, laboratory, and ultrasound variables all decreased significantly during follow‐up, already at 4 weeks (P < 0.001). Fatigue was both cross‐sectionally and longitudinally associated with PROMs, whereas there were no or low associations with clinical, laboratory, or ultrasound assessments of inflammation. Baseline fatigue was predictive of PROMs at 12 and 24 weeks (P < 0.05 and P < 0.001, respectively) but not of any objective assessments.

Conclusion

Fatigue was primarily associated with subjective assessments of disease activity. Thus, the present study supports fatigue to reflect other aspects of RA disease activity than inflammation.