CD98hc regulates the development of experimental colitis by controlling effector and regulatory CD4(+) T cells

Biomimetic MOF Nanoparticles Delivery of C-Dot Nanozyme and CRISPR/Cas9 System for Site-Specific Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) of unknown etiology affecting the colon and rectum. Previous studies have found that reactive oxygen species (ROS) overproduction and transmembrane glycoprotein CD98 (encoded by SLC3A2) upregulation played important roles in the initiation and progression of UC. On the basis of this, a biomimetic pH-responsive metal organic framework (MOF) carrier was constructed to deliver carbon nanodot-SOD nanozyme and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) (CRISPR/Cas9) system for site-specific treatment of UC. In this system, carbon nanodots (C-dots) and CD98 CRISPR/Cas9 plasmid were successfully encapsulated into MOF carrier (ZIF-8 nanoparticles) by a one-pot approach (formed as CCZ), and then camouflaged with macrophage membrane (formed as CCZM). It was worth noting that the C-dot nanozyme showed excellent superoxide dismutase (SOD) enzymatic activity, which could scavenge ROS effectively. As expected, this biomimetic system exhibited pH-responsive, immune escape, and inflammation targeting capability simultaneously. In vitro experiments showed that ROS was significantly eliminated, and CD98 was downregulated by CCZM. In the dextran sulfate sodium salt (DSS)-induced UC model, administration of CCZM significantly ameliorated the inflammation symptoms of mice, including the colon length and pathological parameters such as epithelium integrity and inflammation infiltration. In addition, both in vitro and in vivo results demonstrated that biomimetic nanoparticles effectively reduced the expression of pro-inflammatory cytokines. Overall, this study would provide a promising approach for the precise treatment of UC.

Impaired CD98 signaling protects against graft-versus-host disease by increasing regulatory T cells

Graft-versus-host disease (GvHD) is a major barrier to the broader use of allogenic hematopoietic stem cell transplantation for non-malignant clinical applications. A murine model of C57BL/6 to B6D2F1 acute GvHD was employed with T lymphocytes harboring a deletion of the CD98 heavy chain (CD98hc(-/-)) as donor cells. The CD98hc(-/-) resulted in lower responses to alloantigen stimulation in a mixed leukocyte reaction assay, and prevented the mortality associated with disease progression. The percentage of donor CD8 T lymphocytes was significantly decreased, while the percentage of Foxp3-positive regulatory T cells (Tregs) in recipients was increased by CD98hc(-/-). Decreased expression of FAS, FASL, ICOS, ICOSL, PD-1 and PD-L1 by donor CD8 T cells, and mRNA expression of cytotoxic T cell-related cytokines in the recipients were shown in those with CD98hc(-/-). Fewer infiltrated cells are found in the lungs, liver, tongue and skin of recipients with CD98hc(-/-) compared with the wild type recipients. Taken together, our data indicate that T cell-specific deletion of CD98hc can contribute to the prevention of GvHD development due to the attenuation of lymphocyte migration and by increasing the generation of Treg cells. These findings are expected to make it possible to develop novel approaches for the prevention of GvHD.

The Src kinase Fyn is protective in acute chemical-induced colitis and promotes recovery from disease

Despite progress in understanding enteric inflammation, current therapies, although effective in many patients with inflammatory bowel disease (IBD), have significant side-effects, and, in many patients, it is refractory to treatment. The Src kinase Fyn mediated IFN-γ-induced increased permeability in model epithelia, and so we hypothesized that inhibition of Fyn kinase would be anti-colitic. Mice [B6.129SF2/J wild-type (WT), Fyn KO, or chimeras] received 2.5% dextran sodium sulfate (DSS) or normal water for 10 d and were necropsied immediately or 3 d later. Gut permeability was assessed by FITC-dextran flux, colitis by macroscopic and histologic parameters, and immune cell status by cytokine production and CD4(+) T cell Foxp3 expression. Fyn KO mice consistently displayed significantly worse DSS-induced disease than WT, correlating with decreased IL-10 and increased IL-17 in splenocytes and the gut; Fyn KO mice failed to thrive after removal of the DSS water. Analysis of chimeric mice indicated that the increased sensitivity to DSS was due to the lack of Fyn kinase in hematopoietic, but not stromal, cells, in accordance with Fyn(+) T cell increases in WT mice exposed to DSS and Fyn KO mice having a reduced number of CD4(+)Foxp3(+) cells in baseline or colitic conditions and a reduced capacity to induce Foxp3 expression in vitro. Other experiments suggest that the colonic microbiota in Fyn KO mice is not preferentially colitogenic. Contrary to our expectation, the absence of Fyn kinase resulted in greater DSS-induced disease, and analysis of chimeric mice indicated that leukocyte Fyn kinase is beneficial in limiting colitis.

Cardiac endothelial cell-derived exosomes induce specific regulatory B cells

The mechanism of immune tolerance is to be further understood. The present study aims to investigate the role of the Cardiac endothelial cell (CEC)-derived exosomes in the induction of regulatory B cells. In this study, CECs were isolated from the mouse heart. Exosomes were purified from the culture supernatant of the primary endothelial cells. The suppressor functions of the regulatory B cells were determined by flow cytometry. The results showed that the CEC-derived exosomes carried integrin αvβ6. Exposure to lipopolysaccharide (LPS) induced B cells to express the latent transforming growth factor (TGF)-β, the latter was converted to the active form, TGF-β, by the exosome-derived αvβ6. The B cells released TGF-β in response to re-exposure to the exosomes in the culture, which suppressed the effector T cell proliferation. We conclude that CEC-derived exosomes have the capacity to induce B cells with immune suppressor functions.