Immune and inflammatory cell involvement in the pathology of idiopathic pulmonary arterial hypertension.

RATIONALE: Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction and vascular remodeling. Recent studies have revealed that immune and inflammatory responses play a crucial role in pathogenesis of idiopathic PAH. OBJECTIVES: To systematically evaluate the number and cross-sectional distribution of inflammatory cells in different sizes of pulmonary arteries from explanted lungs of patients with idiopathic PAH versus healthy donor lungs and to demonstrate functional relevance by blocking stromal-derived factor-1 by the Spiegelmer NOX-A12 in monocrotaline-induced pulmonary hypertension in rats. METHODS: Immunohistochemistry was performed on lung tissue sections from patients with idiopathic PAH and healthy donors. All positively stained cells in whole-lung tissue sections, surrounding the vessels, and in the different compartments of the vessels were counted. To study the effects of blocking SDF-1, rats with monocrotaline-induced pulmonary hypertension were treated with NOX-A12 from Day 21 to Day 35 after monocrotaline administration. MEASUREMENTS AND MAIN RESULTS: We found a significant increase of the perivascular number of macrophages (CD68(+)), macrophages/monocytes (CD14(+)), mast cells (toluidine blue(+)), dendritic cells (CD209(+)), T cells (CD3(+)), cytotoxic T cells (CD8(+)), and helper T cells (CD4(+)) in vessels of idiopathic PAH lungs compared with control subjects. FoxP3(+) mononuclear cells were significantly decreased. In the monocrotaline model, the NOX-A12-induced reduction of mast cells, CD68(+) macrophages, and CD3(+) T cells was associated with improvement of hemodynamics and pulmonary vascular remodeling. CONCLUSIONS: Our findings reveal altered perivascular inflammatory cell infiltration in pulmonary vascular lesions of patients with idiopathic pulmonary arterial hypertension. Targeting attraction of inflammatory cells by blocking stromal-derived factor-1 may be a novel approach for treatment of PAH.

Effects of corticotropin-releasing hormone on proopiomelanocortin derivatives and monocytic HLA-DR expression in patients with septic shock.

Little is known about interactions between immune and neuro-endocrine systems in patients with septic shock. We therefore evaluated whether the corticotropin-releasing hormone (CRH) and/or proopiomelanocortin (POMC) derivatives [ACTH, ß-endorphin (ß-END), ß-lipotropin (ß-LPH), α-melanocyte stimulating hormone (α-MSH) or N-acetyl-ß-END (Nac-ß-END)] have any influences on monocyte deactivation as a major factor of immunosuppression under septic shock conditions. Sixteen patients with septic shock were enrolled in a double-blind, cross-over and placebo controlled clinical study; 0.5µg/(kgbodyweighth) CRH (or placebo) were intravenously administered for 24h. Using flow cytometry we investigated the immunosuppression in patients as far as related to the loss of leukocyte surface antigen-DR expression on circulating monocytes (mHLA-DR). ACTH, ß-END immunoreacive material (IRM), ß-LPH IRM, α-MSH and Nac-ß-END IRM as well as TNF-α and mHLA-DR expression were determined before, during and after treatment with CRH (or placebo). A significant correlation between plasma concentration of α-MSH and mHLA-DR expression and an inverse correlation between mHLA-DR expression and TNF-α plasma level were found. Additionally, a significant increase of mHLA-DR expression was observed 16h after starting the CRH infusion; 8h later, the mHLA-DR expression had decreased again. Our results indicate that the up-regulation of mHLA-DR expression after CRH infusion is not dependent on the release of POMC derivatives. From the correlation between plasma concentration of α-MSH and mHLA-DR expression, we conclude that in patients with septic shock the down-regulation of mHAL-DR expression is accompanied by the loss of monocytic release of α-MSH into the cardiovascular compartment.