Copyright @ 2007 by the Shock Society. Unauthorized reproduction of this article is prohibited. PRODUCTION AND EFFECTS OF !-MELANOCYTEYSTIMULATING HORMONE DURING ACUTE LUNG INJURY Gualtiero Colombo,* Stefano Gatti, † Andrea Sordi,* Flavia Turcatti,* Andrea Carlin,* Claudia Rossi,* Caterina Lonati,* and Anna Catania* *Center for Preclinical Investigation and † Liver Transplantation Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ospedale Maggiore Policlinico, Mangiagalli, e Regina Elena, Milano, Italy Received 6 Jun 2006; first review completed 23 Jun 2006; accepted in final form 31 Jul 2006 ABSTRACT—!-MelanocyteYstimulating hormone (!-MSH) is a peptide with broad anti-inflammatory effects. The present research was designed to determine production and effects of !-MSH in acute bleomycin-induced lung injury in rats. Intratracheal bleomycin instillation induced !-MSH expression in lung infiltrating cells and a marked peptide increase in the circulation. In experiments on the therapeutic potential of !-MSH on lung injury, we determined influences of the synthetic !-MSH analogue [Nle 4 -DPhe 7 ]Y!-MSH (NDPY!-MSH) on pulmonary edema, circulating nitric oxide, and gene expression profile in lungs 8 and 24 h after bleomycin instillation. Three main gene categories, known to be involved in the devel- opment of acute lung injury, were explored: stress response, inflammation, and fluid homeostasis. Peptide treatment was associated with a significant reduction in interstitial edema, with a virtually normal wet/dry weight ratio. Several stress- related genes, which were either upregulated or reduced by bleomycin, were only marginally altered during NDPY!-MSH treatment. NDPY!-MSH prevented bleomycin-related transcriptional alterations in genes involved in lung fluid homeo- stasis, including upregulation of Na + /K + Ytransporting ATPase and epithelial sodium channels and downregulation of cystic fibrosis transmembrane conductance regulator. Bleomycin-induced expression of proinflammatory and profibrotic factors (interleukin 6, tumor necrosis factor-!, transforming growth factor-"1, and inducible nitric oxide synthase) and chemokines (chemokine [C-C motif] ligand 2 and chemokine [C-C motif] ligand 5) was likewise significantly reduced by NDPY!-MSH. In conclusion, treatment with the !-MSH analogue NDPY!-MSH greatly improved the clinical and molecular picture of bleomycin-induced lung injury. Treatment with !-MSHYrelated agents can exert beneficial effects in acute lung injury. KEYWORDS—Bleomycin, melanocortin, gene expression profiling, chemokines, cytokines, lung inflammation INTRODUCTION Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe complications of pneumonia, sepsis, trauma, and inhaled irritants. Clinically, ALI is charac- terized by the production of proinflammatory mediators, massive neutrophil influx into the lung, and damage to lung epithelium (1). Activation of leukocytes and release of proinflammatory mediators from multiple cell sources cause both local and distant tissue injury (2). The outcome of ALI/ ARDS is determined by the ability of the injured lung to repopulate the alveolar epithelium with functional cells. However, prognosis for survival is poor and, if resolution occurs, there is evolution to severe lung fibrosis in a substantial proportion of cases (1). Effective therapies for this dire disease are still needed. The model of lung injury based on intratracheal (i.t.) instillation of bleomycin is currently used to investigate cellular and subcellular processes leading to lung fibrosis. However, as signs of lung damage occur immediately after bleomycin instillation, this model is also very helpful to explore early stages of lung injury (3). The early changes are of paramount importance because the development of fibrosis is directly influenced by the extent of initial injury (3). The histological damage induced by bleomycin reproduces closely clinical ALI in humans. Therefore, agents that reduce the severity of ALI in this model may be useful to treat the human disorder. !-MelanocyteYstimulating hormone (!-MSH) is a 13Yamino acid anti-inflammatory peptide produced by many cell types, including monocytes, endothelial cells, and keratinocytes (4Y7). The peptide is released locally and in the circulation upon challenge to the host (8). Blockade of the endogenous molecule with specific antibodies increased the febrile response to pyrogens in rabbits (9), expression of proinflammatory mediators in the circulation, lungs, and liver of mice injected with endotoxin (10), and release of tumor necrosis factor ! (TNF-!), interleukin 6 (IL-6), and nitric oxide (NO) by acti- vated microglia in vitro (11). It seems, therefore, that endoge- nous !-MSH contributes to the control of host reactions. These observations prompted the use of synthetic !-MSH as an anti- inflammatory agent. Experiments in vivo indicate that admin- istration of !-MSH in animal models of human disorders produces multiple beneficial effects on disease parameters (4, 5, 12). Treatment with !-MSH inhibited leukocyte migra- tion into the lungs of a rat model of ALI induced by lung instillation of bacterial endotoxin (13). Protective influences of !-MSH on lung injury were also exerted when damage was caused by renal ischemia and reperfusion (14); in this study, !-MSH administration decreased kidney and lung injury and prevented the activation of transcription factors and stress response genes. Treatment with !-MSH was effective in re- ducing lung damage also when the peptide was administered after renal ischemia, immediately before reperfusion (14), this indicates that delayed treatment can still prevent an on- going damage. Address reprint requests to Anna Catania, MD, Centro di Sperimentazione Preclinica, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via F. Sforza 35, Milano 20122, Italy. E-mail: anna.catania@unimi.it. This study was supported by Progetto di Ricerca Corrente, Ospedale Maggiore di Milano. DOI: 10.1097/01.shk.0000239764.80033.7e Copyright Ó 2007 by the Shock Society 326 SHOCK, Vol. 27, No. 3, pp. 326Y333, 2007