Expression of CXCR6 on CD8+ T cells was up-regulated in allograft rejection

The Role of CXC Chemokines in Cardiovascular Diseases

Cardiovascular disease (CVD) is a class of diseases with high disability and mortality rates. In the elderly population, the incidence of cardiovascular disease is increasing annually. Between 1990 and 2016, the age-standardised prevalence of CVD in China significantly increased by 14.7%, and the number of cardiovascular disease deaths increased from 2.51 million to 3.97 million. Much research has indicated that cardiovascular disease is closely related to inflammation, immunity, injury and repair. Chemokines, which induce directed chemotaxis of reactive cells, are divided into four subfamilies: CXC, CC, CX3C, and XC. As cytokines, CXC chemokines are similarly involved in inflammation, immunity, injury, and repair and play a role in many cardiovascular diseases, such as atherosclerosis, myocardial infarction, cardiac ischaemia-reperfusion injury, hypertension, aortic aneurysm, cardiac fibrosis, postcardiac rejection, and atrial fibrillation. Here, we explored the relationship between the chemokine CXC subset and cardiovascular disease and its mechanism of action with the goal of further understanding the onset of cardiovascular disease.

Diagnostic Biomarkers and Immune Infiltration in Patients With T Cell-Mediated Rejection After Kidney Transplantation

T cell-mediated rejection (TCMR) is an important rejection type in kidney transplantation, characterized by T cells and macrophages infiltration. The application of bioinformatic analysis in genomic research has been widely used. In the present study, Microarray data was analyzed to identify the potential diagnostic markers of TCMR in kidney transplantation. Cell-type identification by estimating relative subsets of RNA transcript (CIBERSORT) was performed to determine the distribution of immune cell infiltration in the pathology. Totally 129 upregulated differently expressed genes (DEGs) and 378 downregulated DEGs were identified. The GO and KEGG results demonstrated that DEGs were mainly associated with pathways and diseases involved in immune response. The intersection of the two algorithms (PPI network and LASSO) contains three overlapping genes (CXCR6, CXCL13 and FCGR1A). After verification in GSE69677, only CXCR6 and CXCL13 were selected. Immune cells Infiltration analysis demonstrated that CXCR6 and CXCL13 were positively correlated with gamma delta T cells (p < 0.001), CD4⁺ memory activated T cells (p < 0.001), CD8⁺ T cells (p < 0.001) and M1 macrophages (p = 0.006), and negatively correlated with M2 macrophages (p < 0.001) and regulatory T cells (p < 0.001). Immunohistochemical staining and image analysis confirmed the overexpression of CXCR6 and CXCL13 in human allograft TCMR samples. CXCR6 and CXCL13 could be diagnostic biomarkers of TCMR and potential targets for immunotherapy in patients with TCMR.

Single-Cell RNA Sequencing Reveals the Migration of Osteoclasts in Giant Cell Tumor of Bone

Giant cell tumor of bone (GCTB) is benign tumor that can cause significant osteolysis and bone destruction at the epiphysis of long bones. Osteoclasts are thought to be highly associated with osteolysis in GCTB. However, the migration of osteoclasts in GCTB remains unclear. A deeper understanding of the complex tumor microenvironment is required in order to delineate the migration of osteoclasts in GCTB. In this study, samples were isolated from one patient diagnosed with GCTB. Single-cell RNA sequencing (scRNA-seq) was used to detect the heterogeneity of GCTB. Multiplex immunofluorescence staining was used to evaluate the cell subtypes identified by scRNA-seq. A total of 8,033 cells were obtained from one patient diagnosed with GCTB, which were divided into eight major cell types as depicted by a single-cell transcriptional map. The osteoclasts were divided into three subsets, and their differentiation trajectory and migration status were further analyzed. Osteoclast migration may be regulated via a series of genes associated with cell migration. Furthermore, four signaling pathways (RANKL, PARs, CD137 and SMEA3 signaling pathway) were found to be highly associated with osteoclast migration. This comprehensive single-cell transcriptome analysis of GCTB identified a series of genes associated with cell migration as well as four major signaling pathways that were highly related to the migration of osteoclasts in GCTB. Our findings broaden the understanding of GCTB bionetworks and provides a theoretical basis for anti-osteolysis therapy against GCTB in the future.

High CXCL-16 levels correlate with symptomatic disease in lung transplant recipients with human cytomegalovirus replication in the allograft

Human cytomegalovirus (HCMV) is an important pathogen in lung transplant recipients (LTRs). In LTRs, HCMV may replicate in the transplanted lung, and this is indicated by HCMV DNA detection in the bronchoalveolar lavage fluid (BALF). Local replication may occur without causing clinical symptoms or, in some patients, it may lead to symptomatic HCMV disease. In the present study, we analyzed whether HCMV replication in the allograft induces CXCL-16, a chemokine that may play a key role in the regulation of mucosal immunity, and investigated whether CXCL-16 levels in BALF can be used to differentiate LTRs with asymptomatic HCMV replication from patients who simultaneously develop disease. In total, BALF samples from 57 LTRs, of whom 8 developed HCMV disease, were assessed for CXCL-16 levels using a quantitative enzyme-linked immunosorbent assay. We found that HCMV replication in the lung triggered a significant rise in CXCL-16 levels in the BALF (p < 0.001, Wilcoxon signed-rank test). Furthermore, the CXCL-16 increase, induced by HCMV, was significantly lower in LTRs who did not develop HCMV disease (p < 0.001, Mann-Whitney U-test). Thus, CXCL-16 is a potential marker that may contribute to identify those LTRs in whom local HCMV replication in the lung remains asymptomatic.

The eye: A window to the soul of the immune system

The eye is considered as an immune privileged site, and with good reason. It has evolved a variety of molecular and cellular mechanisms that limit immune responses to preserve vision. For example, the cornea is mainly protected from autoimmunity by the lack of blood and lymphatic vessels, whereas the retina-blood barrier is maintained in an immunosuppressive state by the retinal pigment epithelium. However, there are several scenarios in which immune privilege is altered and the eye becomes susceptible to immune attack. In this review, we highlight the role of the immune system in two clinical conditions that affect the anterior and posterior segments of the eye: corneal transplantation and age-related macular degeneration. Interestingly, crosstalk between the innate and adaptive immune systems is critical in both acute and chronic inflammatory responses in the eye, with T cells playing a central role in combination with neutrophils and macrophages. In addition, we emphasize the advantage of using the eye as a model for in vivo longitudinal imaging of the immune system in action. Through this technique, it has been possible to identify functionally distinct intra-graft motility patterns of responding T cells, as well as the importance of chemokine signaling in situ for T cell activation. The detailed study of ocular autoimmunity could provide novel therapeutic strategies for blinding diseases while also providing more general information on acute versus chronic inflammation.

Role of T cell recruitment and chemokine-regulated intra-graft T cell motility patterns in corneal allograft rejection

Keratoplasty is the primary treatment to cure blindness due to corneal opacification. However, immune-mediated rejection remains the leading cause of keratoplasty failure. Here, we utilize an in vivo imaging approach to monitor, track, and characterize in real-time the recruitment of GFP-labeled allo-specific activated (Bonzo) T cells during corneal allograft rejection. We show that the recruitment of effector T cells to the site of transplantation determined the fate of corneal allografts, and that local intra-graft production of CCL5 and CXCL9/10 regulated motility patterns of effector T cells in situ, and correlated with allograft rejection. We also show that different motility patterns associate with distinct in vivo phenotypes (round, elongated, and ruffled) of graft-infiltrating effector T cells with varying proportions during progression of rejection. The ruffled phenotype was characteristic of activated effectors T cells and predominated during ongoing rejection, which associated with significantly increased T cell dynamics within the allografts. Importantly, CCR5/CXCR3 blockade decreased the motility, size, and number of infiltrating T cells and significantly prolonged allograft survival. Our findings indicate that chemokines produced locally within corneal allografts play an important role in the in situ activation and dynamic behavior of infiltrating effector T cells, and may guide targeted interventions to promote graft survival.

CXCR6 deficiency ameliorated myocardial ischemia/reperfusion injury by inhibiting infiltration of monocytes and IFN-γ-dependent autophagy

BACKGROUND

Emerging evidence shows that the chemokine CXCL16 plays an important role in the pathogenesis of myocardial remodeling and development of heart failure following ischemia/reperfusion (I/R) injury. CXCR6, the receptor for CXCL16, is also critically involved. However, the underlying mechanism remained uncertain, and the aim of this research was to investigate this mechanism in CXCR6 knockout (KO) mice.

METHODS AND RESULTS

CXCR6 KO mice and wild type (WT) mice had no overt phenotype at baseline in the absence of injury, but difference was shown in response to I/R induction. Compared with WT mice, CXCR6 KO mice exhibited a lower infarction size (31.86 ± 1.808% vs. 43.09 ± 1.519%), and better cardiac function (measured by LVEF, LVFS, +dp/dt, LVEDP, and LVSP) following I/R. Moreover, cardiac levels of IFN-γ and IFN-γ-dependent autophagy were found to be significantly attenuated in CXCR6 KO mice. Further data showed that cardiac-enhanced IFN-γ secretion was not induced by cardiomyocytes, but by infiltrated monocytes in the myocardium in response to I/R injury. In vivo injection of IFN-γ and in vitro co-cultured cardiomyocytes with CD11b+ monocytes confirmed IFN-γ activated autophagic response, and induced cardiac dysfunction in a paracrine manner.

CONCLUSIONS

The study suggested that since disruption of the CXCL16/CXCR6 signaling cascade had a cardio-protective effect against I/R injury, the underlying mechanism might be that I/R triggered the infiltration of monocytes into the myocardium, and induced cardiac autophagy through CXCL16/CXCR6-dependent paracrine secretion of IFN-γ.

Immature renal dendritic cells recruit regulatory CXCR6(+) invariant natural killer T cells to attenuate crescentic GN

Immature renal dendritic cells (DCs) are protective early in murine crescentic GN, but the mechanisms underlying this protection are unknown. Here, depletion of DCs reduced the recruitment of invariant natural killer T (iNKT) cells, which attenuate GN, into the kidney in the early stage of experimental crescentic GN. More than 90% of renal iNKT cells expressed the chemokine receptor CXCR6, and renal DCs produced high amounts of the cognate ligand CXCL16 early after induction of nephritis, suggesting that renal DC-derived CXCL16 might attract protective CXCR6(+) iNKT cells. Consistent with this finding, CXCR6-deficient mice exhibited less iNKT cell recruitment and developed nephritis that was more severe, similar to the aggravated nephritis observed in mice depleted of immature DCs. Finally, adoptive transfer of CXCR6-competent NKT cells ameliorated nephritis. Taken together, these results suggest an immunoprotective mechanism involving immature DCs, CXCL16, CXCR6, and regulatory iNKT cells, which might stimulate the development of new therapeutic strategies for GN.