PT - JOURNAL ARTICLE AU - Chakraborty, Mallinath AU - McGreal, Eamon AU - Davies, Philip AU - Powell, Wendy AU - Akalovich, Svetlana AU - Voitenok, Nikolai AU - Kotecha, Sailesh TI - IL-8<sub>77</sub> isoform in lungs of preterm infants and its processing by neutrophil serine proteases DP - 2011 Sep 01 TA - European Respiratory Journal PG - p503 VI - 38 IP - Suppl 55 4099 - http://erj.ersjournals.com/content/38/Suppl_55/p503.short 4100 - http://erj.ersjournals.com/content/38/Suppl_55/p503.full SO - Eur Respir J2011 Sep 01; 38 AB - Introduction: Persistent neutrophilic (PMN) lung inflammation is strongly implicated in the development of Chronic Lung Disease (CLD) of Prematurity. The 72 amino acid (a.a.) chemokine, IL-872, is a key molecule involved in attracting PMNs to sites of inflammation. The longer 77 a.a. isoform (IL-877) is less potent than IL-872 in vitro. We studied expression of IL-877 in the preterm ventilated lung and its processing by neutrophil serine proteases.Methods: IL-877 was measured by ELISA in bronchoalveolar lavage fluid (BALF) from ventilated preterm infants born at ≤32 weeks gestational age and after conversion by purified PMN serine proteases. Results were compared between the CLD (persistent inflammation) and non-CLD groups (resolved).Results: The majority of IL-8 consisted of the shorter isoforms in the preterm lung (96.3% non-CLD vs 97.1% CLD, p=ns). IL-877 expression correlated well with total IL-8 (p&lt;0.0001) but not with gestation (p=ns).Stimulated adult airway-cells and neonatal PMNs and monocytes expressed IL-877 as the major isoform, suggesting possible expression in the lung. Preterm BALF significantly converted rhIL-877 to shorter isoforms at 18 hours (p&lt;0.05), which was inhibited by α-1 antitrypsin (AAT). Purified neutrophil serine proteases converted IL-877 to shorter isoforms dose-dependently and over time.Conclusions: Majority of IL-8 in the ventilated preterm lung are the potent shorter isoforms. Although potentially expressed in the lung, IL-877 is probably converted to the shorter isoforms by neutrophil serine proteases. Inhibition of conversion by AAT suggests a potential therapeutic role for it in modulating inflammation in the preterm lung.