Plasma exosomal DOK3 reflects immunological states in lung tumor and predicts prognosis of gefitinib treatment.

To identify liquid biomarkers that predict clinical outcomes of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), we enrolled patients with EGFR gene mutation-positive non-small-cell lung cancer who were intended to receive gefitinib treatment. Using plasma samples obtained prior to gefitinib treatment from 12 enrolled patients, we performed comprehensive proteomic analysis of plasma exosomes to explore proteins correlating with tumor reduction rate (TRR), progression-free survival (PFS), or overall survival (OS). Of the detected 1769 proteins, 119, 130, or 119 proteins demonstrated a strong correlation (|r| > 0.5) with TRR, PFS, or OS, respectively. Interestingly, 34 (29%), 41 (32%), or 27 (23%) of them, respectively, were functionally involved in the regulation of the immune response. CD8α chain was consistently listed as a molecule positively correlated with PFS and OS, suggesting that the long-lasting effects of gefitinib may be due to the antitumor effects of CD8+ T cells, as well as the induction of immunogenic apoptosis of tumor cells by blocking the EGFR signaling pathway. Notably, Doking Protein 3 (DOK3), a molecule involved in B-cell receptor signaling, and some immunoglobulin and complement molecules exhibited a clear correlation with PFS longevity of gefitinib treatment. Indeed, the strong expression of DOK3 in B cells was confirmed within tertiary lymphoid structures of lung cancer tissues derived from patients with long PFS. These findings suggest that the patients with active B-cell and T-cell immunity as a host immunological feature are more likely to benefit from gefitinib therapy. Circulating exosomal DOK3 has the potential as a predictive marker of response to gefitinib indicating this immunological feature.

Differentiation of large extracellular vesicles in oral fluid: Combined protocol of small force centrifugation and sedimentation pattern analysis.

Extracellular vesicles (EVs) in biofluids are highly heterogeneous entities in terms of their origins and physicochemical properties. Considering the application of EVs in diagnostic and therapeutic fields, it is of extreme importance to establish differentiating methods by which focused EV subclasses are operationally defined. Several differentiation protocols have been proposed; however, they have mainly focused on smaller types of EVs, and the heterogeneous nature of large EVs has not yet been fully explored. In this report, to classify large EVs into subgroups based on their physicochemical properties, we have developed a protocol, named EV differentiation by sedimentation patterns (ESP), in which entities in the crude large EV fraction are first moved through a density gradient of iodixanol with small centrifugation forces, and then the migration patterns of molecules through the gradients are analysed using a non-hierarchical data clustering algorithm. Based on this method, proteins in the large EV fractions of oral fluids clustered into three groups: proteins shared with small EV cargos and enriched in immuno-related proteins (Group 1), proteins involved in energy metabolism and protein synthesis (Group 2), and proteins required for vesicle trafficking (Group 3). These observations indicate that the physiochemical properties of EVs, which are defined through low-speed gradient centrifugation, are well associated with their functions within cells. This protocol enables the detailed subclassification of EV populations that are difficult to differentiate using conventional separation methods.

Fibulin-4 as a potential extracellular vesicle marker of fibrosis in patients with cirrhosis.

Chronic liver injury leads to decreased liver function and increased fibrosis. Fibrosis is not only associated with the development of portal hypertension and carcinogenesis, but with the occurrence of events and a poor prognosis, highlighting the importance of non-invasive fibrosis assessment in patients. In the present study, we searched for markers related to liver fibrosis via proteomic analysis of small extracellular vesicles (sEVs). In the discovery cohort, proteomic analysis was carried out in the sEVs extracted from the sera of 5 patients with decompensated cirrhosis, 5 patients with compensated cirrhosis, and 5 controls without liver disease. Interestingly, in this cohort, fibulin-4 was significantly associated with cirrhosis while in the validation cohort [formed by 191 patients: 7 patients without disease, 16 patients without liver disease (other diseases), 38 patients with chronic liver disease (CLD), 75 patients with cirrhosis of Child-Pugh class A (36 without hepatocellular carcinoma [HCC], 29 with HCC), and 65 patients with cirrhosis of Child-Pugh class B-C (39 without HCC, 26 with HCC)], fibulin-4/CD9 levels increased with cirrhosis progression. Furthermore, the fibulin-4/CD9 ratio was significantly higher in patients with varices. Immunostaining also revealed strong fibulin-4 expression in cholangiocytes within the fibrous areas and mesothelial cells in liver tissue blood vessels. Taken together, our results suggest that fibulin-4, essential for lysyl oxidase activation, might be a new liver fibrosis marker found in the sEVs of patients with cirrhosis.