Samenvatting
Axial spondyloarthritis (axSpA) is a chronic rheumatic disease developing in young adulthood. Inflammation of the axial skeleton can lead to excessive bone formation (ankylosing) and bone loss. Reduced bone mineral density (BMD) and vertebral fractures (VF) are relatively common in axSpA-patients, also in men and <50 years.
Our study showed that serum biomarkers related to inflammation, bone metabolism and hormones from adipose tissue are associated with spinal radiographic progression at group level. However, these biomarkers have no added value in predicting bone formation at individual patient level.
Serum bone turnover markers (BTM) mirror bone metabolism. SCTX, OC, PINP, and BALP reflect bone loss, regulation, collagen formation, and mineralization, respectively. We established reference values based on a population without bone-related diseases. This allows calculation of BTM Z-scores to correct for age and gender.
Tumor necrosis factor-α (TNF-α) or interleukin-17 (IL17) inhibitors affect bone metabolism in axSpA-patients. During treatment with TNF-α inhibitors, we found an increase in BALP Z-score during the first 2 years, whereafter levels decreased to baseline values. Simultaneously, BMD of the spine improved. However, VF continued to occur or increased in severity during long-term treatment with TNF-α inhibitors. BMD does not seem equal to bone quality. During 2 years of treatment with IL-17 inhibitors, we found a decrease in BALP Z-score. IL-17 inhibitors therefore have a different effect on bone metabolism than TNF-α inhibitors in axSpA-patients.
In summary, this thesis shows the clinical relevance of paying attention to both bone loss and bone formation in the management of axSpA-patients.
Our study showed that serum biomarkers related to inflammation, bone metabolism and hormones from adipose tissue are associated with spinal radiographic progression at group level. However, these biomarkers have no added value in predicting bone formation at individual patient level.
Serum bone turnover markers (BTM) mirror bone metabolism. SCTX, OC, PINP, and BALP reflect bone loss, regulation, collagen formation, and mineralization, respectively. We established reference values based on a population without bone-related diseases. This allows calculation of BTM Z-scores to correct for age and gender.
Tumor necrosis factor-α (TNF-α) or interleukin-17 (IL17) inhibitors affect bone metabolism in axSpA-patients. During treatment with TNF-α inhibitors, we found an increase in BALP Z-score during the first 2 years, whereafter levels decreased to baseline values. Simultaneously, BMD of the spine improved. However, VF continued to occur or increased in severity during long-term treatment with TNF-α inhibitors. BMD does not seem equal to bone quality. During 2 years of treatment with IL-17 inhibitors, we found a decrease in BALP Z-score. IL-17 inhibitors therefore have a different effect on bone metabolism than TNF-α inhibitors in axSpA-patients.
In summary, this thesis shows the clinical relevance of paying attention to both bone loss and bone formation in the management of axSpA-patients.
| Originele taal-2 | English |
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| Kwalificatie | Doctor of Philosophy |
| Toekennende instantie |
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| Begeleider(s)/adviseur |
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| Datum van toekenning | 5-mrt.-2025 |
| Plaats van publicatie | [Groningen] |
| Uitgever | |
| DOI's | |
| Status | Published - 2025 |