Background/Purpose : Increased levels of serum pro-fibrotic cytokines such as IL-4 and IL-13 and plasma CXCL4 have been previously reported in patients with systemic sclerosis (SSc).  These pro-fibrotic cytokines also play an important role for differentiation and migration of eosinophils and eosinophils themselves release pro-fbrotic cytokines such as IL-11 and TGF-beta.  Accordingly, we hypothesized that eosinophils might contribute, at least partly, to fibrotic process of SSc.

Methods : We retrospectively reviewed the peripheral blood eosinophil counts (PB-EOS) in 70 untreated patients with SSc (diffuse 14, limited 56) and compared with those in other major connective tissue diseases including 126 patients with RA, 10 with PM/DM, 19 with primary Sjögren’s syndrome (SjS), 20 with SLE and 8 with mixed connective tissue disease (MCTD).  The diagnosis was made according to the criteria of ACR, except that criteria used for MCTD was that by Japan Ministry of Health, Labor and Welfare.  All the patients were not on treatment by glucocorticoid and/or immunosuppressant. We also evaluated the association with disease severity of SSc, that is, the grade of interstitial lung disease (ILD) and skin sclerosis.  The severity of ILD was graded into 4, grades 0 to grade 3, according to the extent of ILD on chest CT by the method of Gochuico et al. (Arch Intern Med 2008).  Chest CT images were graded by 2 independent respirologists.  The skin sclerosis was evaluated by modified Rodnan’s skin score (mRodnan SS). 

Results : The mean of coefficient of variance of PB-EOS in 8 patients was 0.32, suggesting that PB-EOS are considerably stable.  The order of mean PB-EOS was as follows; diffuse-SSc (mean 312/mcL) > limited-SSc (210) > PM/DM (164) = RA (154) > pSJS (128) > MCTD (73) = SLE (57) (> indicates significantly different).  ILD was observed in 39 % (27/70) of SSc patients, and the numbers of SSc patients with grade 0/1/2/3 were 43/15/9/3, respectively.  PB-EOS positively correlated with ILD grade in SSc (rs = 0.26, p < 0.02), but not in RA (rs = 0.02) and other diseases. M-Rodnan SS also correlated with PB-EOS (rs = 0.35, p = 0.003) and ILD severity (rs = 0.57, p < 0.0001).  

Conclusion : It was suggested that eosinophils contribute, at least in part, to fibrotic process in SSc and anti-eosinophil strategy might become a treatment option when such drugs become available.  It is also suggested that the mechanism of ILD is somewhat different between SSc and RA. Authors have no COI.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/peripheral-blood-eosinophil-counts-increase-in-patients-with-systemic-sclerosis-and-associated-with-its-disease-severity/