Background/Purpose: Anti-Th/To antibodies (Abs) have been reported in patients with systemic sclerosis (SSc). The presence of anti-Th/To Abs is detected in 2-5% of SSc cases and is more frequently observed in the limited cutaneous SSc (lcSSc). In the Japanese population, there is a higher incidence of concurrent gastroesophageal reflux disease (GERD) and interstitial lung disease (ILD), although the severity of these complications tends to be milder compared to European and North American populations. Due to the low expression frequency and few case reports on this Abs, there is no consensus on clinical significance of this Abs.

Methods: Thus, to examine the clinical characteristics of patients with anti-Th/To Abs, we retrospectively identified 10 patients by using the serum immunoprecipitation assays between 2001 and 2021.

Results: Among the anti-Th/To positive cases, only lcSSc was observed, and diffuse cutaneous SSc (dcSSc) was not detected.

Compared to 596 cases of Th/To-negative SSc from our hospital, the modified Rodnan total skin thickness score (mRSS) was significantly lower in the anti-Th/To positive group (2.8 [0-9] vs. 10.1 [0-49], p < 0.05). Additionally, there was a significantly higher rate of ILD (8/9 vs. 143/596, p < 0.01) and Pulmonary arterial hypertension (PAH） (3/9 vs. 41/596, p < 0.05) in the anti-Th/To-positive group compared to the negative group. Although there was no significant difference, GERD was more common in the anti-Th/To positive group (63%) compared to the negative group (44.3%).　No cases of renal crisis were observed in patients with anti-Th/To positive SSc.

When compared to 170 SSc patients with anti-topoisomerase antibodies, which are known to be frequently associated with ILD, there was no significant difference. However, the anti-Th/To-positive group had a higher rate of ILD.

Conclusion: In conclusion, patients with anti-Th/To antibodies exhibit mild skin sclerosis but have an increased risk of developing organ complications such as ILD and PAH in the future.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-features-of-anti-th-to-antibodies-positive-systemic-sclerosis-patients-a-single-center-retrospective-study/