# Antibody Profile of Systemic Sclerosis and Mixed Connective Tissue Disease and Its Relationship with Lung Fibrosis and Pulmonary Hypertension

## TL;DR

This study explores how specific antibodies in systemic sclerosis and mixed connective tissue disease relate to lung fibrosis and pulmonary hypertension.

## Contribution

The study identifies specific antibodies associated with lung fibrosis in systemic sclerosis and mixed connective tissue disease.

## Key findings

- Anti-Scl-70 antibodies are positively correlated with lung fibrosis.
- Anti-centromere, anti-histone, and anti-nucleosome antibodies are negatively correlated with lung fibrosis.
- Antiphospholipid antibodies do not correlate with lung fibrosis or pulmonary hypertension risk.

## Abstract

The most serious complications of systemic sclerosis (SSc) and mixed connective tissue disease (MCTD) include lung fibrosis (LF) and pulmonary hypertension (PH). The aim of this study was to find any association between the serological profile and the incidence of these complications. The tested group included 121 persons (87 SSc, 34 MCTD); mean age 55.6 ± 13.4 years. Patients were qualified for the LF presence group based on HRCT. Likelihood of PH was determined using echocardiography. The presence of antinuclear antibodies (ANA) was assessed using indirect immunofluorescence, ANA-profile, sclerosis-profile (using EUROIMMUN kits), and antiphospholipid antibodies (aPL) (using the ELISA method). Distribution of individual antibody types was at a level similar to the previously described groups in the Polish population and differed from the American and African population. A positive correlation was found between LF and the presence of anti-Scl-70 (p = 0.024) antibodies, negative correlation was found between LF and the presence of anti-histone (p = 0.03), anti-centromere A (p = 0.009), anti-centromere B (p = 0.014), and anti-nucleosomes (p = 0.03) antibodies. No correlation between the presence of aPL and the above complications was found. The prevalence of individual antibody types in SSc and MCTD may have ethnic and geographical grounds. Scl-70 antibodies correlate positively with LF. Anti-centromere, anti-histone, and anti-nucleosome antibodies reduce its risk. No correlation between aPL and the occurrence of LF and elevated PH risk was found.