The association between the decreased expression levels of FOXJ1 and the activation of NF-κB pathway in interstitial lung disease of MRL/Lpr mice

Pulmonary manifestations of systemic lupus erythematosus (SLE) are appearing in 4-5% of patients involving lung in almost half of the cases during the disease course.

We compared the autoimmune pulmonary inflammation in the lung tissue of mice to determine the association between the decreased expression levels of Forkhead Box J1 (FOXJ1) and the activation of the NF-κB pathway in autoimmune pulmonary inflammation of MRL/Lpr mice.

The female BALB/c mice (n=6) and MRL/Lpr mice (n=30) were divided into 5 groups including: a control group (BALB/c), and five MRL/Lpr mice groups (8W, 12W, 16W, 24W, and 32W). The inflammation of the inflammatory cells was determined in lung tissue by the histological analysis. The western blotting was used to examine the expression levels of the age-related FOXJ1, and p50 and p65 proteins in the lungs of MRL/Lpr mice. The expression levels of MMP2 and MMP9 were determined via immunohistochemistry and immunofluorescence.

There were severe infiltrates of lung cells with high levels of tracheal damage, perivascular injury and interstitial inflammatory cell infiltration when the MRL/Lpr mice ranged in age from 16w to 32w than in the healthy MRL/Lpr mice in the control group which were at the age of 8w (p<0.05). Moreover, the reduced expression levels of FOXJ1 were associated with the activation of the NF-κB pathway in interstitial lung disease of MRL/Lpr mice via the modulation of p50 and p65. In addition, the expression levels of MMP2 and MMP9 pro-inflammation factors increased in the lungs of the MRL/Lpr mice as they ranged in age from 16w to 32w.

The level of FOXJ1 expression might be a hint at the degree of lung disease in lupus-prone mice.