Zhihui Liang

Interleukin-33 ameliorates ischemic brain injury in experimental stroke through promoting Th2 response and suppressing Th17 response.

Ischemic stroke causes brain injury with activation of an inflammatory response that can contribute to clinical impairment. As a novel cytokine of the interleukin-1 (IL-1) family, IL-33 has been suggested to be involved in regulating pathophysiology and inflammatory responses in the central nervous system (CNS). However, the role and underlying mechanisms of IL-33 in ischemic stroke remain poorly understood. Here, adult male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) for stroke induction. The MCAO procedure resulted in the enhanced Th1 and Th17 immune responses from 6h after transient cerebral ischemia/reperfusion even up to day 3. Meanwhile, the protein and mRNA level of IL-33 expression was significantly decreased at 6h and 72 h, but not at 24h after MCAO. Moreover, recombinant mouse IL-33 administration substantially attenuated ischemic brain damage and neurological deficit at 24h and 72 h, but not at 6h after MCAO. Interestingly, the reduced CNS inflammation in IL-33-treated MCAO mice may be at least partly due to an induced immuno-shift of Th cells from Th1 to Th2 response and suppressing Th17 immune response. These findings demonstrate that IL-33 can play a protective role after MCAO and may be a new target for therapy of ischemic stroke.

Dimerization of soluble HLA-G by IgG-Fc fragment augments ILT2-mediated inhibition of T-cell alloresponse.

Background. Human leukocyte antigen (HLA)-G, a nonclassical HLA class I molecule, induces a wide range of tolerogenic immunological effects by means of interaction with its inhibitory receptors. However, recent studies show that HLA-G dimer formation is essential to bind to its receptors and exhibit its effects. Methods. In this study, a soluble divalent HLA-G/IgG molecule (sHLA-G dimer) was constructed. Its inhibitory effect on T-cell alloresponse was studied with mixed lymphocyte reaction in vitro, which was set up by mixing inactivated T1 cells with HLA-mismatched peripheral blood lymphocytes in the presence or absence of the sHLA-G dimer. Results. The results show that sHLA-G dimer inhibits T-cell alloresponse by reducing proliferation of both CD4+ and CD8+ T cells and suppressing generation of alloreactive cytotoxic T lymphocytes at nanomole concentration. The inhibition of the sHLA-G dimer is observed to be more effective than that of sHLA-G monomer. Our results also indicate that sHLA-G dimer up-regulates inhibitory receptor ILT2 on alloreactive CD8+ T cells, which contributes to the significant inhibition on T-cell alloresponse. Conclusion. The sHLA-G dimer formed by IgG-Fc fragment shows more inhibitory effects on alloreactive T cells, which may have implications for allotransplantation.

Peptide-dependent inhibition of alloreactive T-cell response by soluble divalent HLA-A2/IgG molecule in vitro.

Background. Induction of peripheral tolerance in an antigen-specific manner is a critical goal of transplant biology. The specificity and avidity of multimerized peptide/major histocompatibilty complexes suggest their potential ability to modulate antigen-specific T-cell sensitization and effector functions. Methods. A soluble divalent HLA-A2/IgG molecule (HLA-A2 dimer) was constructed and loaded with a self-protein origin peptide (Tyr368–376) to form a divalent Tyr/HLA-A2 molecule (Tyr/HLA-A2 dimer), which allowed for specific targeting to the epitope-specific cytotoxic T lymphocytes in bulk alloreactive T cells. Alloreactive T-cell response was induced by coculture of Tyr368–376-pulsed T2 cells (T2/Tyr) with peripheral blood lymphocytes of HLA-A2-negative (HLA-A2-ve) sample; five samples of HLA-A2-ve individuals were included in this study. After the coculture in the presence of Tyr/HLA-A2 dimer, the suppression of the dimer on alloresponse was characterized by analyzing allogeneic T-cell proliferation, specific cytolytic activity against the T2/Tyr, and specific Tyr/HLA-A2 tetramer staining. Results. The Tyr/HLA-A2 dimer suppresses alloreactive T-cell response by inhibiting its proliferation and cytotoxicity against specific target T2/Tyr in vitro, and it is interesting that the suppression is peptide-specific. The Tyr/HLA-A2 tetramer staining suggests the reduced function of CD8+ T cell is caused by inhibiting the generation of the epitope-specific alloreactive T cells by the Tyr/HLA-A2 dimer in three samples. Moreover, the existence of epitope-specific but function-negative T cells in the other two samples suggests that another mechanism might exist that is involved in silencing alloreactive responses by the dimer. Conclusion. Peptide-loaded dimers offer a novel approach to induce peptide-specific immunosuppression and may be useful in promoting graft survival.

Serum DKK-1 level in the development of ankylosing spondylitis and rheumatic arthritis: a meta-analysis

To explore the association of serum Dickkopf-1 (DKK-1) levels with the development of ankylosing spondylitis (AS) and rheumatic arthritis (RA) in humans, databases including PubMed, EBSCO, Springerlink, Ovid, WANFANG and China National Knowledge Infrastructure (CNKI) were searched to identify relevant studies. On the basis of rigorous inclusion and exclusion criteria, case–control studies of the relationships between serum DKK-1 levels and AS and RA published before December 2014 were enrolled. Statistical analyses were performed using Comprehensive Meta-analysis 2.0 (CMA 2.0). Seven case–control trials with a total of 300 AS patients, 136 RA patients and 232 healthy controls were included in this study. Meta-analysis results revealed that DKK-1 serum levels were significantly higher in AS patients than in normal controls (standard mean differences (s.m.d.)=0.301, 95% confidence interval (CI)=0.094–0.507, P=0.004), whereas no significant difference in DKK-1 serum levels was observed between RA patients and healthy controls (s.m.d.=0.798, 95% CI=−2.166–3.763, P=0.598). Serum DKK-1 level may be closely related to the development of AS but not of RA.

CD8low T-cell subpopulation is increased in patients with chronic hepatitis B virus infection

Recent studies suggest that CD8(+) T cells with down-regulated CD8 expression (CD3(+)CD8(low) T cells) represented as a distinct phenotype of CD8(+) T cells are increased and linked to disease severity in some chronically persistent infection, such as chronic HIV and parasite infection. However, the role of CD3(+)CD8(low) T cells in the context of chronic HBV infection is poorly understood. In this study, peripheral blood samples of 47 chronic hepatitis B patients and 19 healthy controls were collected and tested for the frequency and phenotype of CD8(low) T cells. The circulating CD8(low) T cells were significantly more frequent in the patients compared to those in healthy controls, and the CD8(low) T cells in the patients expressed less IFN-γ and more mTGF-β1 than those in the controls, suggesting their type-2 polarized and suppressive properties. Meanwhile, the concentrations of plasma soluble HLA class I molecules were found elevated in the patients, and positively associated with the frequencies of CD8(low) T cells. Furthermore, the CD8(low) T-cell frequency in the HLA-A2-positive patients (n=21) was found negatively correlated with the T-cell responsiveness against the HBc₁₈₋₂₇ peptide, the latter was impaired as revealed by IFN-γ Elispot assay. Our findings suggested that a better understanding of the involvement of CD8(low) T cells in chronically persistent HBV infection would add to our knowledge of the impaired T-cell response in the patients.

Allo-restricted CTLs generated by coculturing of PBLs and autologous monocytes loaded with allogeneic peptide/HLA/IgG1-Fc fusion protein.

The graft‐versus‐leukemia effect of allogeneic marrow transplantation suggests the dramatic effect of the allogeneic T cell to eradicate malignant disease. Preparation and adoptive transfusion of tumor‐specific T cells from HLA‐mismatched donors might be expected to circumvent CTL tolerance to the tumor. In this study, a soluble, divalent HLA‐A2 molecule was constructed with the Fc part of human IgG1 and was pulsed with a peptide related to melanoma tyrosinase 368–376 [Tyr368–376 (Tyr)] to form the Tyr/HLA‐A2 dimer, which allowed loading onto monocytes via interaction of the Fc and FcR. The HLA‐A2‐negative (HLA‐A2‐ve) monocytes loaded with the Tyr/HLA‐A2 dimer acted as allo‐APC with copies of a single allogeneic epitope. After coculture of the HLA‐A2‐ve PBLs and autologous monocytes loaded with the dimer, CD8+ cells in the coculture show an obvious proliferation and increased frequency of Tyr/HLA‐A2 tetramer‐stained cells. The sorted Tyr/HLA‐A2 tetramer‐positive CD8+ cells display an elevated cytotoxic activity against HLA‐A2‐positive melanoma cells expressing tyrosinase endogenously (i.e., SK‐Mel‐5) but little against tyrosinase‐negative melanoma cells (i.e., A375). The coculture of PBLs and autologous monocytes loaded with allogeneic peptide/HLA complexes offers a novel approach to expand allo‐restricted, peptide‐specific CTLs, which might be a potential arsenal for treatment of patients with malignant disease, if the tumor‐related epitope were defined.

Soluble MOG35-55/I-Ab Dimers Ameliorate Experimental Autoimmune Encephalomyelitis by Reducing Encephalitogenic T Cells

The MOG35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice is a useful animal model to explore therapeutic approaches to T cell-mediated autoimmune diseases because the dominant T-cell epitope(s) have been defined. It is rational that antigen-specific immunosuppression can be induced by using MHC-peptide complexes as specific TCR ligand(s) that interact with autoreactive T cells in the absence of co-stimulation. In this study, a soluble divalent MOG35-55/I-Ab fusion protein (MOG35-55/I-Ab dimer) was constructed to specifically target the autoreactive CD4+ T cells in the EAE mouse. Intraperitoneal administration of the MOG35-55/I-Ab dimer significantly delayed and ameliorated EAE symptoms by reducing EAE-related inflammation in the mouse CNS and reducing encephalitogenic Th1 and Th17 cells in the peripheral lymphoid organs. We observed that dimer intervention at a concentration of 1.2 nM suppressed MOG35-55 peptide-specific 2D2 transgenic T cells (2D2 T cells) proliferation by over 90% after in vitro activation with MOG35-55 peptide. The mechanisms involved in this antigen-specific dimer-mediated suppression were found to be downregulated TCR-CD3 expression as well as upregulated expression of membrane-bound TGF-β (mTGF-β) and IL-10 suppressive cytokines by the autoreactive CD4+ T cells. Collectively, our data demonstrates that soluble divalent MHC class II molecules can abrogate pathogenic T cells in EAE. Furthermore, our data suggests that this strategy may provide an efficient and clinically useful option to treat autoimmune diseases.

CD8(low)CD28(-) T Cells: A Human CD8 T-Suppressor Subpopulation With Alloantigen Specificity Induced by Soluble HLA-A2 Dimer In Vitro.

CD8+ suppressor T cells have been demonstrated to provide protection of allografts from rejection. We previously reported that soluble peptide/HLA-A2 dimer shows peptide-specific inhibitory effects on alloresponse in a coculture of peptide-pulsed T2 cells with HLA-A2 negative lymphocytes in vitro. Here we found a subset of CD8lowCD28– T cells that was induced in the dimer-treated coculture. Importantly, this population showed hyporesponsiveness to the alloantigen restimulation as well as alloantigen-specific suppression on alloreactive T cells in a cell–cell contact-dependent fashion. The suppressive mechanisms of CD8lowCD28– T cells involved an elevated expression of membrane-bound TGF-β1, but not Foxp3, CTLA-4, or IL-10. Furthermore, an over-represention of CD8lowCD28– T cells was observed in the patients after allogeneic platelet transfusion and positively correlated with the elevated concentrations of plasma HLA class I antigens. Our findings demonstrated that soluble HLA-A2 dimer could efficiently induce the tolerant CD8lowCD28– T cells with alloantigen-specific suppression on alloreactive T cells. This study might provide a new strategy for preparation of donor-specific suppressor T cells and represent an attractive alternative for induction of allograft tolerance.

Viral specific cytotoxic T cells inhibit the growth of TfR-expressing tumor cells with antibody targeted viral peptide/HLA-A2 complex

A fusion protein of single chain antibody (scFv) specific for transferrin receptor (TfR, CD71) and viral peptide/HLA-A2 complex was prepared in this study to redirect cytotoxic T cells (CTLs) of viral specificity to tumor cells by attaching the ligand of T cell receptor (TCR) to tumor cells via binding of TfR scFv to TfR. The results demonstrate that the fusion protein can attach the active virus-peptide/HLA-A2 complex to HLA class I-negative, TfR-expressing K562 cells through binding of TfR scFv to TfR, and mediate cytotoxicity of viral peptide-specific CTLs against K562 cells in vitro. In addition, the fusion protein can induce inhibition of solid tumor formation and improve survival time in tumor xenograft nude mouse with the injection of the sorted viral peptide-specific CTLs generated by co-culture of peripheral blood lymphocytes from HLA-A2 positive donors with inactivated T2 cells pulsed with the viral peptide.

CD103+CD8+ T lymphocytes in non-small cell lung cancer are phenotypically and functionally primed to respond to PD-1 blockade

CD103+CD8+ tumor infiltrating lymphocytes (TILs) have been linked to prolonged survival in various types of cancer including non-small cell lung cancer (NSCLC). However, the factors associated with the retention of CD103+CD8+ TILs in lung cancer tissues remain largely unknown. Additionally, the contribution of CD103+CD8+ TILs to effective PD-1 based immunotherapy has not been fully elucidated. In this study, we identified that the expression levels of E-cadherin and TGF-β were significantly correlated with the distribution and the density of CD103+ TILs in lung cancer tumor tissues. Unexpectedly, we observed that CD103+CD8+ TILs that expressed higher levels of PD-1 co-express Ki-67. Moreover, CD103+CD8+ TILs expressed an increased level of T-bet compared to their counterparts, indicating these cells may be better armed for immunotherapy. Lastly, PD-1 pathway blockade led to a significantly increased production of IFN-γ by CD103+CD8+ TILs, suggesting CD103+CD8+ TILs could serve as a predictive biomarker for PD-1 based immunotherapy.