Mini-bronchoalveolar lavage fluid can be used for biomarker identification in patients with lung injury by employing 1H NMR spectroscopy

lung injury and has low survival rates. More than 150,000 cases of ARDS are diagnosed every year in the US alone, according to the National Heart, Lung, and Blood Institute database. 1H nuclear magnetic resonance (NMR) has been a well-established technique for the recognition of biomarkers in various body fl uids [1]. Over last few decades, investigators have searched for novel biomarkers for the diagnosis and prognosis of patients with lung injury [2]. Bronchoalveolar lavage (BAL) fl uid has been used for years for diagnosis and prognosis of lung injury and related pulmonary diseases by means of various tech niques [2]. BAL fl uid is favored over minibroncho alveolar lavage (mBAL) for diagnostic as well as research purposes since the former is extracted from the immediate vicinity of alveoli. mBAL requires that fl uid be taken from proximal alveoli and bronchi but can provide information about biochemical events happening inside the lungs. In this letter, we show, via 1H NMR spectroscopy, that small metabolites present in BAL fl uid and mBAL fl uid are similar and can be used for metabolomicrelated studies [3]. NMR spectroscopy of BAL has been used for metabolomic analysis of cystic fi brosis [4]. 1H NMR spectroscopy of mBAL fl uid can be used for other prospective studies such as those that are conducted to diff erentiate between infec tive (pulmonary) and infl amma tory (non-pulmonary) ARDS and to determine the type of microbial infection associated with them [5,6]. Th ough extracted from a diff erent location, mBAL fl uid has small metabolites similar to those of BAL fl uid. Th is is shown in Figures 1a and 1b, which depict onedimensional and two-dimen sional NMR spectra of BAL fl uid and mBAL fl uid, which are represented by red and black colors, respectively. Qualitatively, only choline metabolite, which is present in mBAL fl uid and absent in BAL fl uid, is diff erent. Quantitatively, most of the metabo lite resonances had similar intensities. In a recently published article, we showed that by combining 1H NMR spectroscopy of mBAL fl uid with multivariate statistical analysis, we can clearly diff erentiate between patients with lung injury and healthy controls [7]. In this fi rst report of 1H NMR of mBAL fl uid, we showed an association of small meta bo lites with severity of infection. Taurine and threonine levels were found to be elevated in cases of ARDS, and have been correlated to severity of infection earlier. Addition ally, concentrations of leucine, valine and isoleucine (muscle breakdown products), arginine, glycine, aspartic acid, succinate, acetate, and glutamate were elevated and proline level was found to be decreased in cases of ARDS. Hence, on the basis of our results, we conclude that mBAL fl uid combined with 1H NMR spectroscopy can be used for diagnosis and prognosis of ARDS and its severity.