Abstract

BACKGROUND: Anti-NXP2 antibody (anti-NXP2 Ab) is a myositis-specific antibody (MSA) which has been previously described in idiopathic inflammatory myopathies (IIM). Interstitial lung diseases (ILD) in such context would occur in 10 to 50% of patients according to the study and are linked to a poor prognosis. Based on a case patients, we assessed the association of anti-NXP2 Ab and ILD.

METHODS: We performed an observational study (Marseille, France), based on a retrospective analyze of data from patients with positive anti-NXP2 Ab independently of their clinical status, between 12-2015 and 01-2018.

RESULTS: Twenty-four adult patients with positive anti-NXP2 Ab were identified. The mean age was 55±15 yrs (range 18-75), with a predominance of females (n=18, 75% of cases); 10 patients had previously a diagnosis of IIM (42%), only 3 of them (12.5%) experienced respiratory symptoms. HR CT-scan could be reviewed in 13 patients (54%), 8 had normal CT-scan (62%) and 5 had various and nonspecific abnormalities (38%), with 2 ILD (1 COP and 1 NSIP). Pulmonary function tests (PFT) were available for 11 patients (46%) with a mean FEV1 of 89±21% of predicted (range 49-112), mean FVC of 9±19%pred (58-121%) and altered diffusing capacity for carbon monoxide (DLCO/SB) with a mean 60±16% of predicted (37-86%).

CONCLUSION: In our series anti-NXP2 Ab were not associated with respiratory symptoms or with CT-scan abnormalities of ILD. However, even if not all patients had available PFT, diffusing capacity would be more frequently impaired in such cohort. Our findings may support a potential pathogenic role of anti-NXP2 Ab in lung disease associated with IIM. Further studies are required to comfort our data.