Pathological features of pulmonary vasculopathy in interstitial lung disease-associated pulmonary hypertension.

BACKGROUND

The prognosis of interstitial lung disease-associated pulmonary hypertension remains poor, and the characteristics of the vasculopathy and its underlying pathogenesis are unclear.

OBJECTIVE

To investigate the pathological characteristics of pulmonary vasculopathy in interstitial lung disease-associated pulmonary hypertension.

METHODS

Autopsy specimens were collected from four groups: control (n = 2), pulmonary arterial hypertension (n = 3), interstitial lung disease-associated pulmonary hypertension (n = 6), and interstitial lung disease without pulmonary hypertension (n = 3). The morphology from the arteries to the veins was quantitively compared, along with the expression of pathogenetic factors and target proteins of pulmonary vasodilators.

RESULTS

The percent area stenosis of the muscular arteries and veins were 83 % (71 %-92 %) and 54 % (41 %-70 %), respectively, in the interstitial lung disease-associated pulmonary hypertension group, which were not significantly different compared with other groups except controls. In contrast, for microvessels, the percent area stenosis and muscularization rate in moderate fibrotic areas were significantly higher, and capillary multilayering was also more prominent, in the interstitial lung disease-associated pulmonary hypertension group compared with the interstitial lung disease without pulmonary hypertension group. The expression of pathogenetic factors was not different between interstitial lung disease groups with and without pulmonary hypertension; however, prostaglandin I2 receptors were more strongly expressed in the microvessel wall of interstitial lung disease-associated pulmonary hypertension group than in pulmonary arterial hypertension group.

CONCLUSIONS

Interstitial lung disease-associated pulmonary hypertension is pathologically characterized by microvessel remodeling and capillary multilayering. Increased expression of prostaglandin I2 receptor in the microvessels suggests different responses to stimulators of the pathway.