First of all, I want to send many thanks to APSR for this great opportunity to study in Chronic Inflammatory Lung Disease Research Laboratory, Lung Research Unit, Hanson Institute and Thoracic Medicine, Royal Adelaide Hospital, South Australia. Through the 5-month course (from August to December 2016), I had chance to work with world leading experts in lung disease pathology, to learn techniques of contemporary immunology including immunofluorescence, flow cytometry, ELISA and Western Blot, and to gain experience in designing and carrying out translation lung research projects.
My first project was about the changes of sphingolipid signaling in macrophages exposed to cigarette smoke (CS) in vitro or isolated from COPD patients. My experiments focused on sphingosine kinase 1 (SK1, an enzyme responsible for synthesis of sphingosine-1 phosphate, S1P) and spinster homolog 2 (SPNS2), a transporter of S1P. Lung tissue samples were obtained from 14 patients with lung cancer (7 COPD versus 7 non-COPD). Cryostat sections were immunolabelled with antibodies specific for SK1 and SPNS2. Images were captured under laser scanning microscope and analysed using ImageJ software for the intensity of signal and distribution. In the results, I observed nonsignificant increased signals of both SK1 and SPNS2 in COPD macrophages compared with controls (P>0.05). However, in line with previous data on THP-1 macrophages exposed to CS in vitro (Tran et al JLB 2016), SK1 in COPD alveolar macrophages showed a loss of its membrane-like localization. Furthermore using both primary alveolar macrophages obtained from non-COPD donors and THP-1 macrophages in models of in vitro CS exposure, we observed significant increase of SPNS2. Importantly, in THP-1 macrophages this CS-induced effect could be reverted by S1P or FTY720 (a S1P analogue) at concentration of 10-100 nmol. Previous data from this lab also showed that, compared to the macrophage cell type, the SPNS2 expression in the epithelial cell type, both in cell culture and in a mouse model, responded to cigarette smoke in an opposite direction. Importantly, phagocytosis function in macrophages isolated from mouse lung was shown positively correlated with SPNS2 expression levels in bronchial epithelium. These findings provide a framework for a manuscript in which I'm proud to be a co-author (Tran HB, Jersmann H, Truong TT, et al. "Disrupted epithelial/macrophage cross-talk via Spinster homologe 2-mediated S1P signaling may drive defective macrophage phagocytic function in COPD", report at the 21st meeting of APSR, Bangkok, Thailand, 12-15 November 2016; manuscript in preparation).
Spns2 up-regulation in alveolar macrophages of patients having COPD and smokers
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with a thin layer on cellular membrane
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My second project was about cigarette smoke induction of NLRP3inflammasome) activation in macrophages. Similar to SPNS2, the signals of both NLRP3 and IL-1β increased significantly in THP-1 macrophages when exposed to CS 10% for 24h. In this experiment, I have shown that ZYVAD (caspase-1 inhibitor) and Glyburide (a diabetes medicine and NLRP3 antagonist) at concentration of 20umol significantly downregulated CS-induced particulate immunofluorescence of NLRP3 and IL-1β. This result provided a crucial evidence of the NLRP3 inflammasome activation in CS-exposed macrophages and supported the notion that inflammasomes could be potential therapeutic targets in COPD. Moreover, using S1P and FTY720 as inhibitors of CS-induced NLRP3 inflammasome activation, our preliminary data suggested a link between sphingolipid and inflammasome pathways. These data have also been recently presented at the 21st scientific meeting of APSR (Tran HB, Hamon R, Truong TT et al, "Cigarette smoke-induced inflammation in macrophages is initiated by NLRP3/AIM2 inflammasomes: involvement of the Sphingosine-1-phosphate signaling system"; manuscript in preparation).
Finally, once again, my sincere thanks to APSR and the Hodge's team for this amazing experience and all unforgettable memories. Adelaide is not a crowed city, but I really love its peace and stunning beauty. More importantly, working together with Prof Sandra Hodge, Prof Hubertus Jesmann and Dr Hai Bac Tran as well as other staff has given me many invaluable skills which will be very useful in my future plans. For me, they are my best team ever!
Tung Thanh Truong
Tuberculosis and Lung Disease Department, Military Hospital 175, HoChiMinh city
Dr Tung Thanh Truong (in the blue NYC T-shirt)(Click photo to enlarge)