Dysregulation of the renin-angiotensin system during lung ischemia-reperfusion injury.

UNLABELLED: Aim/Purpose of the Study: Activation of the renin-angiotensin system leading to increased angiotensin-(1-7) (Ang-(1-7)) and decreased angiotensin 2 (Ang 2) levels may be a new therapeutic approach to reduce acute lung injury. Prolylcarboxypeptidase (PRCP) and prolyloligopeptidase (PREP) are capable of hydrolyzing Ang 2 into Ang-(1-7). However, their relation with circulating Ang 2 levels after lung ischemia-reperfusion injury (LIRI) has never been explored. This study determines whether the activity and expression of PRCP and PREP in plasma and lung tissue is related to circulating Ang 2 levels in a murine model of LIRI. MATERIALS AND METHODS: LIRI in Swiss mice (6 animals per group) was induced by temporary left lung hilar clamping (1 h) followed by 0, 1 or 24 h of reperfusion. Animals in the sham group received thoracotomy only. PRCP activity was measured via RP-HPLC, PREP activity using a fluorogenic substrate and plasma Ang 2 levels via ELISA. Western blotting was used to determine the PRCP and PREP protein expression profiles in left lung tissue. RESULTS: Plasma Ang 2 levels significantly rise after lung ischemia and remain increased after 1 h and 24 h of reperfusion compared to the sham group. While a significant decrease in plasma PREP activity was found after 24 h of reperfusion, a transient increase in plasma PRCP activity was observed after ischemia. However, no correlation with plasma Ang 2 levels could be demonstrated. The activity profiles of PRCP and PREP and the protein expression of PRCP in the lung tissues remained unchanged after LIRI. CONCLUSIONS: LIRI causes a dysregulation of circulating Ang 2 levels and plasma PREP activity, although no direct link between both phenomena could be shown. The activity profile of pulmonary PRCP and PREP was not significantly changed after LIRI, which implies a minor role for local PRCP and PREP in the ischemic lung itself.

Malignant Pleural Mesothelioma : Rationale for a New TNM Classification.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rare but aggressive thoracic malignancy with a poor prognosis. In this regard, a well-defined staging system is of utmost importance in order to correctly diagnose and assign an appropriate treatment to the patient. METHODS: The current TNM-staging system (7th edition) enables to either clinically or pathologically stage the severity of the disease according to extension of the tumor (T), number of nodes (N) and presence of metastases (M). Patients with stage I-III are considered for surgery, while palliative treatment is indicated for stage IV patients according to the current classification. RESULTS: Despite its widespread use, the validity of this staging system is questioned due to the low prevalence, histological variety and retrospective nature of the previous study design. In addition, the role of specific treatment modalities including surgery, has yet to be determined, especially for treatment of early-stage disease. In this regard, the International Association for the Study of Lung Cancer (IASLC) initiated the multi-centre, prospective "Mesothelioma Staging Project" in order to address limitations of the 7th edition and to optimize the staging system in accordance to current needs. CONCLUSIONS: An improved staging system will contribute to the design of prospective multi-institutional clinical trials investigating novel treatment strategies for mesothelioma. In this way comparison of outcome between different medical centres also becomes feasible.