Targeting Pulmonary Fibrosis by SLC1A5-Dependent Glutamine Transport Blockade.

The neutral amino acid glutamine plays a central role in TGF-ß (transforming growth factor-ß)-induced myofibroblast activation and differentiation. Cells take up glutamine mainly through a transporter expressed on the cell surface known as solute carrier SLC1A5 (solute carrier transporter 1A5). In the present work, we demonstrated that profibrotic actions of TGF-ß are mediated, at least in part, through a metabolic maladaptation of SLC1A5 and that targeting SLC1A5 abrogates multiple facets of fibroblast activation. This approach could thus represent a novel therapeutic strategy to treat patients with fibroproliferative diseases. We found that SLC1A5 was highly expressed in fibrotic lung fibroblasts and fibroblasts isolated from idiopathic pulmonary fibrosis lungs. The expression of profibrotic targets, cell migration, and anchorage-independent growth by TGF-ß required the activity of SLC1A5. Loss or inhibition of SLC1A5 function enhanced fibroblast susceptibility to autophagy; suppressed mTOR, HIF (hypoxia-inducible factor), and Myc signaling; and impaired mitochondrial function, ATP production, and glycolysis. Pharmacological inhibition of SLC1A5 by the small-molecule inhibitor V-9302 shifted fibroblast transcriptional profiles from profibrotic to fibrosis resolving and attenuated fibrosis in a bleomycin-treated mouse model of lung fibrosis. This is the first study, to our knowledge, to demonstrate the utility of a pharmacological inhibitor of glutamine transport in fibrosis, providing a framework for new paradigm-shifting therapies targeting cellular metabolism for this devastating disease.

Genomic Characterization Revealed PM2.5-Associated Mutational Signatures in Lung Cancer Including Activation of APOBEC3B.

Fine particulate matter (PM2.5) exposure causes DNA mutations and abnormal gene expression leading to lung cancer, but the detailed mechanisms remain unknown. Here, analysis of genomic and transcriptomic changes upon a PM2.5 exposure-induced human bronchial epithelial cell-based malignant transformed cell model in vitro showed that PM2.5 exposure led to APOBEC mutational signatures and transcriptional activation of APOBEC3B along with other potential oncogenes. Moreover, by analyzing mutational profiles of 1117 non-small cell lung cancers (NSCLCs) from patients across four different geographic regions, we observed a significantly higher prevalence of APOBEC mutational signatures in non-smoking NSCLCs than smoking in the Chinese cohorts, but this difference was not observed in TCGA or Singapore cohorts. We further validated this association by showing that the PM2.5 exposure-induced transcriptional pattern was significantly enriched in Chinese NSCLC patients compared with other geographic regions. Finally, our results showed that PM2.5 exposure activated the DNA damage repair pathway. Overall, here we report a previously uncharacterized association between PM2.5 and APOBEC activation, revealing a potential molecular mechanism of PM2.5 exposure and lung cancer.

Mechanisms of antigen presentation to T cells in murine graft-versus-host disease: cross-presentation and the appearance of cross-presentation.

Recipient antigen-presenting cells (APCs) initiate GVHD by directly presenting host minor histocompatibility antigens (miHAs) to donor CD8 cells. However, later after transplantation, host APCs are replaced by donor APCs, and if pathogenic CD8 cells continue to require APC stimulation, then donor APCs must cross-present host miHAs. Consistent with this, CD8-mediated GVHD is reduced when donor APCs are MHC class I(-). To study cross-presentation, we used hosts that express defined MHC class I K(b)-restricted miHAs, crossed to K(b)-deficient backgrounds, such that these antigens cannot be directly presented. Cross-priming was surprisingly efficient, whether antigen was restricted to the hematopoietic or nonhematopoietic compartments. Cross-primed CD8 cells were cytolytic and produced IFN-γ. CD8 cells were exclusively primed by donor CD11c(+) cells, and optimal cross-priming required that they are stimulated by both type I IFNs and CD40L. In studying which donor APCs acquire host miHAs, we made the surprising discovery that there was a large-scale transfer of transmembrane proteins from irradiated hosts, including MHC class I-peptide complexes, to donor cells, including dendritic cells. Donor dendritic cells that acquired host MHC class I-peptide complexes were potent stimulators of peptide-specific T cells. These studies identify new therapeutic targets for GVHD treatment and a novel mechanism whereby donor APCs prime host-reactive T cells.

Minor histocompatibility antigens: allo target molecules for tumor-specific immunotherapy.

Minor histocompatibility antigens have to be considered as key molecules in the stem cell-based immunotherapy of malignancies. Allogeneic stem cell transplantation (SCT) is a well-established and effective therapy for advanced hematologic malignancies. The apparent powerful graft-versus-leukemia effect of SCT led clinicians to apply SCT for the treatment of metastatic solid tumors. The SCT-based graft-versus-tumor reaction in the allogeneic human leukocyte antigen-matched SCT setting is mediated by allo-immune effectorcells directed against tumor-related target antigens. The target molecules involved in the allo-immune graft-versus-tumor reaction are tumor-specific antigens, tumor-associated antigens, and tissue- and cell-specific minor histocompatibility antigens. The power of the minor histocompatibility antigens in the human leukocyte antigen-identical, stem cell-based immunotherapy for malignancies is their "allo-ness." As opposed to tumor-associated self antigens, the complexes of MHC and allo-target peptide are likely to be more immunogeneic than the major histocompatibility complex and self-target peptide complexes. Moreover, minor histocompatibility allo-antigens are not subject to self tolerance. Earlier minor histocompatibility antigens were seen as alien entities, disturbing the success of the so ideally matched organ and SCT donor-recipient combinations. To date, minor histocompatibility antigens can be set in the favorable light of useful tools for immunotherapy for cancer. The first clinical application of the hematopoietic minor histocompatibility antigens HA-1 and HA-2 is currently being explored in a stem cell-based setting for hematologic malignancies. Because HA-1 is also expressed on carcinoma cells, a stem cell-based vaccination trial for patients with metastatic breast or renal cancer is about to start as well. The immunotherapeutic potential of minor histocompatibility antigens demands serious searches for new minor histocompatibility antigens and analyses of their phenotype frequency, tissue distribution, and functional membrane expression. The minor histocompatibility antigens meeting the prerequisites for specific immunotherapy for malignancies, such as membrane expression and tissue and/or cell specificity, may offer the curative tools for stem cell-based immunotherapy for various hematologic and nonhematologic malignancies.