Ablation Of CD4 Research Articles

CD4 T cell intrinsic arginase 1 controls the kinetics of Th1 induction and contraction

Abstract Arginase 1 (ARG1), the enzyme catalyzing the conversion of arginine to ornithine and urea, is a hallmark of IL-10 producing immunosuppressive M2 macrophages, however ARG1 activity in T cells is disputed. Here we demonstrate that Arg1, but not Arg2, expression induction is a key feature of lung CD4 T cells during mouse in vivo influenza infection. Ablation of CD4 T cell-intrinsic Arg1 unexpectedly accelerated both the virus-specific Th1 effector response and its IL-10-associated contraction. Biologically, this led to efficient viral clearance, yet significantly reduced lung pathology. Surprisingly, loss of Arg1 in CD4 T cells did not result in disturbed intracellular ornithine or polyamine levels. Instead, by employing unbiased transcriptomic and metabolomic approaches, we found that Arg1 deficiency triggered altered glutamine metabolism, and rebalancing the glutamine flux normalized the Arg1 deficient T cell response. Further, the role of Arg1 in CD4 T cells was distinct from that of its’ isoenzyme Arg2, as ablation of CD4 T cell intrinsic Arg2 resulted in normal Th1 responses, and instead altered Th2 and Th17 responses. Finally, CD4 T cells from rare patients with a deficiency in ARG1, or from healthy donors with CRISPR-Cas9-mediated ARG1 deletion, recapitulated the mouse data, demonstrating that ARG1 also plays a CD4 T cell intrinsic role in human Th1 responses. Collectively, CD4 T cell-intrinsic ARG1, functions as an unexpected pace-keeper of human and mouse T helper 1 (Th1) responses with implications for Th1-associated tissue pathologies. Supported by grants from NIH (5K22HL125593 to M.K.) the Intramural Research Program of the NIH (NIDDK ZIA/DK075149 to B.A. and NHLBI ZIA/HL006223 to C.K.)

Abstract WP142: T Cells Aggravate Intracerebral Hemorrhage Injury

Intracerebral hemorrhage (ICH), a devastating form of stroke, has a mortality of 40% and no available treatment. Inflammation contributes to the genesis and expansion of perihematomal edema (PHE) in ICH, thus driving secondary injury and subsequent neurological deterioration. This study was carried out to elucidate contributions of lymphocytes, specifically CD4 + cells in the formation of PHE and ICH-induced neural injury. Upon examination of brain sections of ICH patients, we observed abundant CD4 + T cells among the PHE-infiltrating immune cells as early as 24 hours post-ictus. Analogous findings in ICH mouse model induced with autologous blood or collagenase injection confirmed the phenomenon. Using anti-CD4 antibody to deplete CD4 + T cells, we find that brain-infiltrating CD4 + T cells exacerbates acute ICH injury in mice by reducing BBB integrity and promoting leukocytes recruitment with early and time-dependent CD4 + T cells activation. Brain infiltrating CD4 + T cells exhibit activated transcriptome signatures, promoting local inflammation via IL-17. In the hemorrhagic brain, CD4 + T cells induces CD31 + endothelial cell apoptosis via death receptor-ligands TRAIL-DR5 pathway; specific ablation of CD4 + T cells with depleting antibody results in reduced PHE volume and improved long-term neurological outcome. In all, these data sheds new lights on T cell-mediated immune responses contributing to PHE and brain injury in ICH.

Specific ablation of CD4+ T-cells promotes heart regeneration in juvenile mice.

Unlike adult cardiomyocytes, neonatal cardiomyocytes can readily proliferate that contributes to a transient regenerative potential after myocardial injury in mice. We have recently reported that CD4+ regulatory T-cells promote this process; however, the role of other CD4+ T-cell subsets as well as CD8+ T-cells in postnatal heart regeneration has been less studied. Methods: by comparing the regenerating postnatal day (P) 3 and the non-regenerating P8 heart after injury, we revealed the heterogeneity of CD4+ and CD8+ T-cells in the myocardium through single cell analysis. We also specifically ablated CD4+ and CD8+ T-cells using the lytic anti-CD4 and -CD8 monoclonal antibodies, respectively, in juvenile mice at P8 after myocardial injury. Results: we observe significantly more CD4+FOXP3- conventional T-cells in the P8 heart when compared to that of the P3 heart within a week after injury. Surprisingly, such a difference is not seen in CD8+ T-cells that appear to have no function as their depletion does not reactivate heart regeneration. On the other hand, specific ablation of CD4+ T-cells contributes to mitigated cardiac fibrosis and increased cardiomyocyte proliferation after injury in juvenile mice. Single-cell transcriptomic profiling reveals a pro-fibrotic CD4+ T-cell subset in the P8 but not P3 heart. Moreover, there are likely more Th1 and Th17 cells in the P8 than P3 heart. We further demonstrate that cytokines of Th1 and Th17 cells can directly reduce the proliferation and increase the apoptosis of neonatal cardiomyocytes. Moreover, ablation of CD4+ T-cells can directly or indirectly facilitate the polarization of macrophages away from the pro-fibrotic M2-like signature in the juvenile heart. Nevertheless, ablation of CD4+ T-cells alone does not offer the same protection in the adult heart after myocardial infarction, suggesting a developmental change of immune cells including CD4+ T-cells in the regulation of age-related mammalian heart repair. Conclusions: our results demonstrate that ablation of CD4+ but not CD8+ T-cells promotes heart regeneration in juvenile mice; and CD4+ T-cells play a distinct role in the regulation of heart regeneration and repair during development.

Intracellular Salmonella enterica infection is controlled in mononuclear phagocytes that attract CXCR3+ Th1 cells in vivo and persists in those that do not

Abstract Salmonella enterica (Se) is a prototypical bacterial pathogen that persists in myeloid cells in secondary lymphoid organs and is controlled by interferon-g-producing CD4+ Th1 cells. How Th1 cells limit the infection without eliminating it is not understood. Using a PhoNdTomato S. enterica strain, we found Se bacteria inside tissue macrophages and recruited monocytes, some of which expressed inducible nitric oxide synthase (iNOS) or CXCL9 and CXCL10 ligands for CXCR3 expressed by Se-specific Th1 cells. The iNOS+ cells were clustered in red pulp regions devoid of T cells and surrounded by CXCL9/CXCL10+ cells and interspersed Th1 cells. Ablation of CD4+ T cells or blockade of CXCR3 lead to preferential loss of bacterial control in the CXCL9/CXCL10+ areas. These results suggest that Se bacteria are controlled inside myeloid cells in regions that attract CXCR3+ Th1 cells and harbored inside myeloid cells in areas that do not.

Inactivation of Junctional Adhesion Molecule-A Enhances Antitumoral Immune Response by Promoting Dendritic Cell and T Lymphocyte Infiltration

Junctional adhesion molecule-A (JAM-A)-null dendritic cells (DCs) are more motile and effective than their wild-type counterpart in promoting contact hypersensitivity reaction. Here, we show that the growth and aggressiveness of pancreatic islet cell carcinoma induced by SV40 T antigen expression in beta cells (Rip1Tag2 mice) are significantly reduced in JAM-A-null mice. Because these tumor cells do not express JAM-A, we focused on changes in stroma reactivity. In the absence of JAM-A, tumors showed a small but significant reduction in angiogenesis and a marked increase in the immune reaction with enhanced infiltration of DCs (CD11c+ and MHC-II+) and CD4+ and CD8+ lymphocytes. In contrast, phagocyte number was not affected. DC capacity to produce cytokines was not significantly altered, but transmigration through JAM-A-null endothelial cells was increased as compared with JAM-A-positive endothelium. On adoptive transfer, JAM-A(-/-) DCs were recruited to tumors at slightly but significantly higher rate than JAM-A(+/+) DCs. Ablation of CD4+ and CD8+ cells with specific antibodies abrogated the inhibitory effect of JAM-A deletion on tumor growth and angiogenesis. These findings support the idea that, in the Rip1Tag2 tumor model, abrogation of JAM-A reduces cancer development by increasing antitumor immune response.

Gene therapy: Advances and limitations

Recombinant adenovirus vectors are efficient at transferring genes into somatic tissues but are limited for use in clinical gene therapy by immunologic factors that result in the rapid loss of gene expression and inhibit secondary gene transfer. This study demonstrates that systemic coadministration of recombinant adenovirus with soluble CTLA4lg, which is known to block co-stimulatory signals between T cells and antigen presenting cells, leads to persistent adenovirus gene expression in mice without long-term immunosuppression. This form of immunotherapy greatly enhances the likelihood that recombinant adenovirus vectors will be useful for human gene therapy. Recombinant adenoviruses are attractive vehicles for liver-directed gene therapy because of the high efficiency with which they transfer genes to hepatocytes in vivo. First-generation recombinant adenoviruses deleted of E1 sequences also express recombinant and early and late viral genes, which lead to development of destructive cellular immune responses. Previous studies indicated that class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTLs) play a major role in eliminating virusinfected cells. The present studies utilize mouse models to evaluate the role of T-helper cells in the primary response to adenovirus-mediated gene transfer to the liver. In vivo ablation of CD4+ cells or interferon γ (INF-γ) was sufficient to prevent the elimination of adenovirus-transduced hepatocytes, despite the induction of a measurable CTL response. Mobilization of an effective TH1 response as measured by in vitro proliferation assays was associated with substantial upregulation of MHC class I expression, an effect that was prevented in IFN-γ-deficient animals. These results suggest that elimination of virus-infected hepatocytes in a primary exposure to recombinant adenovirus requires both induction of antigen-specific CTLs as well as sensitization of the target cell by the TH1-mediated activation of MHC class I expression.

CD8+ cell activation to a major mastocytoma rejection antigen, P815AB: requirement for tum- or helper peptides in priming for skin test reactivity to a P815AB-related peptide.

Delayed-type hypersensitivity (DTH) responses, mediated by CD8+ cells and detected by skin test assay, occur in sensitized mice in response to challenge with class I-restricted antigenic peptides of mutagenized (tum-) P815 mastocytoma cells. In contrast, a nonapeptide related to a tumor rejection antigen, P815AB, failed in this study to elicit DTH after sensitization of mice with irradiated tumor cells or adoptive transfer of P815AB-pulsed dendritic cells. Unresponsiveness, however, could be overcome by immunization with tumor cells co-expressing P815AB and tum- antigens. When used for cell pulsing in vitro, a mixture of P815AB and tum- peptides was also highly effective in inducing anti-P815AB reactivity, as was the combined use of P815AB and class II-restricted peptides of tetanus toxin or Plasmodium berghei circumsporozoite protein. While the effector phase of the CD8+ cell-mediated DTH to P815AB was unaffected by the ablation of CD4+ cells, the same treatment, or neutralization of IFN-gamma, negated the induction of reactivity if it occurred at the time of sensitization. Thus, defective activation of CD4+ cells may contribute to the poor immunogenicity of P815AB. Besides providing an insight into the mechanisms of anti-tumor protection induced by tum- cells, these data offer useful information for the design of vaccination strategies against identified tumor antigens.