Enhancing Efficacy of TCR-engineered CD4 + T Cells Via Coexpression of CD8α.

Adoptive cell therapy with T cells expressing affinity-enhanced T-cell receptors (TCRs) is a promising treatment for solid tumors. Efforts are ongoing to further engineer these T cells to increase the depth and durability of clinical responses and broaden efficacy toward additional indications. In the present study, we investigated one such approach: T cells were transduced with a lentiviral vector to coexpress an affinity-enhanced HLA class I-restricted TCR directed against MAGE-A4 alongside a CD8α coreceptor. We hypothesized that this approach would enhance CD4 + T-cell helper and effector functions, possibly leading to a more potent antitumor response. Activation of transduced CD4 + T cells was measured by detecting CD40 ligand expression on the surface and cytokine and chemokine secretion from CD4 + T cells and dendritic cells cultured with melanoma-associated antigen A4 + tumor cells. In addition, T-cell cytotoxic activity against 3-dimensional tumor spheroids was measured. Our data demonstrated that CD4 + T cells coexpressing the TCR and CD8α coreceptor displayed enhanced responses, including CD40 ligand expression, interferon-gamma secretion, and cytotoxic activity, along with improved dendritic cell activation. Therefore, our study supports the addition of the CD8α coreceptor to HLA class I-restricted TCR-engineered T cells to enhance CD4 + T-cell functions, which may potentially improve the depth and durability of antitumor responses in patients.

Engineering Cancer Antigen-Specific T Cells to Overcome the Immunosuppressive Effects of TGF-ß.

Adoptive T cell therapy with T cells expressing affinity-enhanced TCRs has shown promising results in phase 1/2 clinical trials for solid and hematological tumors. However, depth and durability of responses to adoptive T cell therapy can suffer from an inhibitory tumor microenvironment. A common immune-suppressive agent is TGF-ß, which is secreted by tumor cells and cells recruited to the tumor. We investigated whether human T cells could be engineered to be resistant to inhibition by TGF-ß. Truncating the intracellular signaling domain from TGF-ß receptor (TGFßR) II produces a dominant-negative receptor (dnTGFßRII) that dimerizes with endogenous TGFßRI to form a receptor that can bind TGF-ß but cannot signal. We previously generated specific peptide enhanced affinity receptor TCRs recognizing the HLA-A*02-restricted peptides New York esophageal squamous cell carcinoma 1 (NY-ESO-1)157-165/l-Ag family member-1A (TCR: GSK3377794, formerly NY-ESO-1c259) and melanoma Ag gene A10254-262 (TCR: ADP-A2M10, formerly melanoma Ag gene A10c796). In this article, we show that exogenous TGF-ß inhibited in vitro proliferation and effector functions of human T cells expressing these first-generation high-affinity TCRs, whereas inhibition was reduced or abolished in the case of second-generation TCRs coexpressed with dnTGFßRII (e.g., GSK3845097). TGF-ß isoforms and a panel of TGF-ß-associated genes are overexpressed in a range of cancer indications in which NY-ESO-1 is commonly expressed, particularly in synovial sarcoma. As an example, immunohistochemistry/RNAscope identified TGF-ß-positive cells close to T cells in tumor nests and stroma, which had low frequencies of cells expressing IFN-γ in a non-small cell lung cancer setting. Coexpression of dnTGFßRII may therefore improve the efficacy of TCR-transduced T cells.

Live attenuated B. pertussis BPZE1 rescues the immune functions of Respiratory Syncytial virus infected human dendritic cells by promoting Th1/Th17 responses.

Respiratory Syncytial virus (RSV) is the leading cause of acute lower respiratory tract viral infection in young children and a major cause of winter hospitalization. Bordetella pertussis is a common cause of bacterial lung disease, affecting a similar age group. Although vaccines are available for B. pertussis infection, disease rates have recently increased in many countries. We have therefore developed a novel live attenuated B. pertussis strain (BPZE1), which has recently undergone a successful clinical phase I trial. In mice, BPZE1 provides protection against disease caused by respiratory viral challenge. Here, we analyze the effect of BPZE1 on antiviral T cell responses induced by human monocyte-derived dendritic cells (MDDC). We found that BPZE1 influences antiviral immune responses at several levels, enhancing MDDC maturation, IL-12p70 production, and shifting T cell cytokine profile towards a Th1/Th17 pattern. These data were supported by the intracellular signaling analysis. RSV infection of MDDC caused MyD88-independent STAT1 phosphorylation, whereas BPZE1 activated MyD88-dependent signaling pathways; co-infection caused both pathways to be activated. These findings suggest that BPZE1 given during infancy might improve the course and outcome of viral lung disease in addition to providing specific protection against B. pertussis infection.

Chlamydia pneumoniae modulates human monocyte-derived dendritic cells functions driving the induction of a Type 1/Type 17 inflammatory response.

Chlamydia pneumoniae is a respiratory pathogen involved in the onset of chronic inflammatory pathologies. Dendritic cells (DC), are major players in spreading of C. pneumoniae from the lungs, a crucial step leading to disseminated infections. Less is known concerning modulation of DC functions consequent to encounter with the bacterium. In order to address this aspect, human monocyte-derived (MD)DC were infected with C. pneumoniae. After internalization bacterial counts increased in MDDC, as well as the expression of CPn1046, a gene involved in bacterial metabolism, with a peak 48 h after the infection. Infected MDDC switched to the mature stage, produced IL-12p70, IL-1ß, IL-6, and IL-10, and drove a mixed Type 1/Type 17 polarization. Intracellular pathways triggered by C. pneumoniae involved Toll-like receptor (TLR) 2. Indeed, TLR2 was activated by C. pneumoniae in transfected HEK 293 cells, and C. pneumoniae-mediated phosphorylation of ERK1/2 was inhibited by an anti-TLR2 antibody in MDDC. When an ERK1/2 inhibitor was used, IL-12p70 and IL-10 release by MDDC was reduced and T cell polarization shifted towards a Type 2 profile. Overall, our findings unveiled the role played by TLR2 and ERK1/2 induced by C. pneumoniae to affect DC functions in a way that contributes to a Type 1/Type 17 pro-inflammatory response.

Human melanoma cells express FGFR/Src/Rho signaling that entails an adhesion-independent caveolin-1 membrane association.

Caveolae have been indicated as a center of cytoskeleton regulation for Src kinase/Rho GTPase signaling. In addition, Src recruitment on intact cortical actin cytoskeleton appears to be required for bFGF/FGFR signal activation. Recently, we established a relationship between caveolin-1 (Cav-1) expression and cell migration in human malignant melanoma, constitutively activated by a bFGF autoregulatory loop. This work intends to investigate whether caveolae's asset, through bFGF/FGFR/c-Src/Rho signaling, could be related to melanoma cell anchorage. Accordingly, we revealed the existence of a FGFR/Src kinase pathway in Cav-1 enriched detergent-resistant membranes (DRMs) of Me665/1 metastatic melanoma cells, as confirmed by FGFR silencing. Moreover, we determined the expression and phosphorylation levels of Cav-1/Src/Erk signal pathway as a function of FGFR activation and cell density. A sucrose density gradient ultracentrifugation was employed to monitor Cav-1 membrane association and buoyancy in Me665/1 cells treated for actin fragmentation or for altered phosphorylation signals. As a result, melanoma cells show remarkable resistance to Cav-1 disassembly, together with persisting cell signal activity, being Src and Cav-1 crucial modulators of Rho GTPases. In conclusion, our study primarily highlights, in a metastatic melanoma cell line expressing caveolin, the circumstances whereby caveola structural and functional endurance enables the FGFR/Src/Rho GTPases pathway to keep on cell progression.

Immunomodulatory activities of surface-layer proteins obtained from epidemic and hypervirulent Clostridium difficile strains.

Surface-layer proteins (SLPs) have been detected in all Clostridium difficile strains and play a role in adhesion, although an involvement in the inflammatory process may also be supposed, as they cover the bacterial surface and are immunodominant antigens. The aim of this study was to evaluate the immunomodulatory properties of SLPs obtained from hypervirulent and epidemic (H/E) or non-H/E C. difficile strains, to try to determine whether they contribute to hypervirulence. SLPs were purified from H/E PCR ribotype 027 and 001 and non-H/E PCR ribotype 012 C. difficile strains, and the ability to modulate these properties was studied in human ex vivo models of monocytes and monocyte-derived dendritic cells (MDDCs). The results indicated that SLPs were able to induce immunomodulatory cytokines [interleukin (IL)-1ß, IL-6 and IL-10] in monocytes. SLPs induced maturation of MDDCs, which acquired enhanced antigen-presenting activity, a crucial function of the mature stage. SLP-primed MDDCs expressed high levels of IL-10, an important regulatory cytokine. No significant differences were found in the activation induced in monocytes and MDDCs by SLP preparations from H/E and non-H/E strains. Overall, these findings show an important role for SLPs in modulation of the immune response to C. difficile. However, SLPs from H/E strains did not show a specific immunomodulatory pattern compared with SLPs from non-H/E strains, suggesting that SLPs are not involved in the increased severity of infection peculiar to H/E strains.