Background/Purpose: Interleukin (IL)-34 is a hematopoietic cytokine, which promotes survival, proliferation, and differentiation of monocytes and macrophages. We investigated serum IL-34 levels in patients with systemic sclerosis (SSc).

Methods: The numbers of subjects enrolled in this study were as follows; 43 diffuse cutaneous SSc (dcSSc) patients, 15 limited cutaneous SSc (lcSSc) patients, and 20 healthy controls.

Results: Serum IL-34 levels in dcSSc patients were 10.97 ± 1.42 pg/mL (mean ± s.e.m), which was significantly higher than lcSSc (5.16 ± 1.16 pg/mL) and healthy controls (3.81 ± 0.77 pg/mL). SSc patients with increased serum IL-34 levels suffered from interstitial lung disease (ILD) more frequently than those with normal levels. When we checked the correlations between serum IL-34 levels and ILD markers, serum IL-34 levels negatively correlated with the percentage of predicted vital capacity (r = -0.32, P < 0.01), while they positively correlated with ground-glass opacity score (r = 0.49, P < 0.01) and fibrosis score (r = 0.31, P < 0.05) on chest computed tomography. Serum IL-34 levels also positively correlated with serum KL-6 levels (r = 0.33, P < 0.01) and surfactant protein D levels (r = 0.46, P < 0.01). There was no association between serum IL-34 levels and the presence of anti-topoisomerase I, anti-centromere, or anti-polymerase III antibody.

Conclusion: Increased serum IL-34 levels were associated with greater frequency and severity of ILD in SSc patients, suggesting that serum IL-34 levels could be a useful serologic marker for SSc-associated ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/elevated-serum-interleukin-34-levels-are-correlated-with-interstitial-lung-disease-in-systemic-sclerosis/