Aim of the study: Scleroderma-related interstitial lung disease (SLD) is the major cause of mortality in patients with systemic sclerosis (SSc). CCL2 is a chemokine which exerts strong pro-inflammatory and pro-fibrotic function. In the present study we aimed to evaluate in vitro expression of CCL2 by the peripheral blood mononuclear cells (PBMC) of SSc patients with and without SLD.
Material and methods: Twenty-three SSc patients (11 with and 12 without SLD) and 12 age- and sex-matched healthy controls (HC) were included in the study. Expression of RNA was assessed by means of real-time polymerase chain reaction and CCL2 concentrations – with commercially available ELISA kits in PBMC cultured with and without stimulation with lipopolysaccharide (LPS).
Results: Both, spontaneous expression of CCL2 on RNA levels and concentration of CCL2 in the supernates of unstimulated PBMC were significantly higher in patients with SLD as compared with SSc patients without SLD. Stimulation with LPS led to dramatic increase in expression of CCL2 RNA and CCL2 concentrations in PBMC cultures in all subjects studied. LPS-stimulated expression of CCL2 RNA and the concentrations of CCL2 in LPS-stimulated PBMC cultures were significantly higher in patients with SLD than in those without SLD. Patients with SLD had significantly higher skin core and higher frequency
of anti-topoisomerase I antibodies as compared with SSc patients without SLD. However, in multivariate regression analyses including disease subset (diffuse or limited SSc) and the presence of anti-topoisomerase I antibody, spontaneous and LPS-stimulated expression of CCL2 RNA, and the concentration of CCL2 in LPS-stimulated PBMC were independently associated with the presence of SLD.
Conclusions: We show that expression of CCl2 in PBMC is associated with the risk SLD in patients with SSc. The results of our study indicate that increased expression of CCl2 by PBMC might play a role in the pathogenesis of SLD.