Immunopathological aspects of schistosomiasis-associated pulmonary arterial hypertension.

Objectives: Pulmonary hypertension is a lethal complication of chronic hepatosplenic schistosomiasis. Little is known of the underlying (immuno-)histopathological characteristics of lung vasculopathy.

Methods: We characterized vasculopathy and inflammation in lung tissue of 10 patients with Schistosomiasis-associated PH (SCH-PH) in comparison to 22 idiopathic pulmonary arterial hypertension (IPAH) patients and 10 normal controls. SCH-PH cases were younger than controls.

Results: Plexiform lesions and/or angiomatoid lesions were found in 10/10 SCH-PH, and 19/22 IPAH patients (χ² p = 0.22). Lung granulomas with Schistosoma eggs were found in 2/10 of SCH-PH cases. PAH cases had increased peri-arterial density of CD3+ T cells, chymase+ and tryptase+ mast cells when compared to controls (p ≤ 0.047). SCH-PH showed increased density of CD4+ cells when compared to controls (p = 0.025), paralleled by an increased density of dendritic CD83+ cells when compared to both controls and IPAH patients (p ≤ 0.022).

Conclusion: Both SCH-PH and IPAH feature plexogenic arteriopathy and increased periarterial T cell and mast cell density. SCH-PH and IPAH differ only with respect to the density of dendritic CD83+ cells. These findings imply ongoing antigenic stimulation in SCH-PH, yet a pattern of pulmonary vasculopathy similar to IPAH, suggestive of a final common pathway in their pathogenesis of PAH.