Targeting Th (Th17 and Th2) suppressive and stimulatory effect on cytotoxic T cells

As the name indicates, T-helper cells are shown to help in primary and secondary cellular and humoral immune responses. They behave as conductors of immune responses. Conferring immunity to various kinds of antigens, the immune system has evolved different cell types. There are different terminally differentiated helper cells such as Th1, Th2, TFh, Th17, Treg, Th9, and Th22 cells tailored to combat different pathogens. Production of any subtype of cells depends on the type of antigen, dose of antigen, mode of entry, and cytokine milieu in the microenvironment. An infection or an aberrant growth of tumor cells or an autoimmunity occurs when there is an imbalance in immune responses. Since CD4+ T cells are the conductors controlling different arms of immune-responses, the most frequent imbalances of immune response in the above conditions occur from deregulated CD4+ T cell responses. Because of the importance associated with CD4+ T cells, understanding the patho-physiology and biology associated with CD4+ T cells is crucial. Our study addresses the role of CD4+ Th17 cells in tumor immunity, in autoimmune type 1 diabetes (T1D), and in experimental autoimmune encephalitis (EAE). We have also considered the biology associated with CD4+ Th2 cells. In tumor immunity, it was demonstrated by various studies that CD4+ Th17 cells induce antitumor immunity, leading to the eradication of established tumors. However, the mechanism of CD8+ CTL activation by CD4+ Th17 cells and the distinct role of CD4+ Th17 and CD4+ Th17 activated CD8+ CTLs in antitumor immunity were still elusive. In this study we have demonstrated that CD4+ Th17 cells acquired pMHC-I and expressed RORγt, IL-17 and IL-2. CD4+ Th17 cells did not have any direct in vitro tumor cell killing activity, but still were able to stimulate CD8+ CTL responses via IL-2 and pMHC-I, but not IL-17 signalling. The therapeutic effect of CD4+ Th17 cells was shown to be associated with IL-17, but not IFN-γ, and was mediated by CD4+ Th17-stimulated CD8+ CTLs via the perforin pathway, which were recruited into B16 melanoma via CD4+ Th17-stimulated CCL20 chemoattraction. These results elucidated distinct roles of CD4+ Th17 and CD4+ Th17-stimulated CD8+ CTLs in the induction of preventive and therapeutic antitumor immunity, which may greatly impact the development of CD4+ Th17-based cancer immunotherapy. In autoimmunity, earlier studies showed that both CD4+ Th17 cells and CD8+ CTLs were involved in T1D and EAE. However, their relationship in pathogenesis of autoimmune diseases was still elusive. In this study, we found that CD4+ Th17 cells stimulated OVA- and MOGspecific CD8+ CTL responses, respectively, in mice. When CD4+ Th17 cells were transferred into (i) transgenic RIP-mOVA or (ii) RIP-mOVA mice treated with anti-CD8 antibody to eliminate Th17-stimulated CD8+ T cells, we found that OVA-specific CD4+ Th17-stimulated CD8+ CTLs, but not CD4+ Th17 cells themselves, induced diabetes in RIP-mOVA. In cases of mice injected with MOG-specific CD4+Th17 lymphocytes, CD4+ Th17 but not CD4+ Th17- activated CD8+ CTL induced EAE in C57BL/6 mice. These results demonstrate the distinct roles of CD4+ Th17 and CD4+ Th17-stimulated CD8+ CTLs in the pathogenesis of autoimmune diseases, which may have great impact on the overall understanding of CD4+ Th17 cells in the pathogenesis of autoimmune diseases. To study the functional conversion of naive CD4+ T-helper cells into Th1 or Tr1 cells under Th2 differentiation culture conditions, we generated OVA-specific wild-type (WT) Th2, and Th2(IL-5 KO), or Th2(IL-5 KO), or Th2(IL-6 KO), or Th2(IL-10 KO) cells, and assessed their capacity in modulating DCOVA-induced CD8+ cytotoxic T lymphocyte (CTL) responses and antitumor immunity in WT C57BL/6 mice. We demonstrated that GATA-3-expressing Th2 cells enhanced DCOVA-induced CTL responses via IL-6 secretion. We also showed that IL-6 and IL- 10 gene deficient Th2(IL-6 KO) and Th2(IL-10 KO) cells, but not IL-4 and IL-5 gene deficient Th2(IL-4 KO) and Th2(IL-5 KO) cells, behaved like functional Tr1 and Th1 cells by inhibiting and enhancing DCOVA-induced OVA-specific CD8+ CTL responses and antitumor immunity, respectively. We further demonstrated that inhibition and enhancement of DCOVA-induced OVAspecific CTL responses by Th2(IL-6 KO) and Th2(IL-10 KO) cells were mediated by their immune suppressive IL-10 and pro-inflammatory IL-6 secretions, respectively. Taken together, our results suggest that deletion of a single cytokine gene IL-6 and IL-10 converts CD4+ Th2 cells into functional CD4+ Tr1 and Th1 cells under Th2 differentiation condition. Our data thus not only provide new evidence for another type of CD4+ T cell plasticity, but also have a potential to impact the development of a new direction in immunotherapy of allergic diseases

Lung gene therapy—How to capture illumination from the light already present in the tunnel

AbstractGene therapy has been considered as the most ideal medical intervention for genetic diseases because it is intended to target the cause of diseases instead of disease symptoms. Availability of techniques for identification of genetic mutations and for in vitro manipulation of genes makes it practical and attractive. After the initial hype in 1990s and later disappointments in clinical trials for more than a decade, light has finally come into the tunnel in recent years, especially in the field of eye gene therapy where it has taken big strides. Clinical trials in gene therapy for retinal degenerative diseases such as Leber's congenital amaurosis (LCA) and choroideremia demonstrated clear therapeutic efficacies without apparent side effects. Although these successful examples are still rare and sporadic in the field, they provide the proof of concept for harnessing the power of gene therapy to treat genetic diseases and to modernize our medication. In addition, those success stories illuminate the path for the development of gene therapy treating other genetic diseases. Because of the differences in target organs and cells, distinct barriers to gene delivery exist in gene therapy for each genetic disease. It is not feasible for authors to review the current development in the entire field. Thus, in this article, we will focus on what we can learn from the current success in gene therapy for retinal degenerative diseases to speed up the gene therapy development for lung diseases, such as cystic fibrosis

Transient blocking of NK cell function with small molecule inhibitors for helper dependant adenoviral vector-mediated gene delivery

Abstract One major challenge in gene therapy is the host immune responses against viral vectors. Previous studies indicate the involvement of NK cells in stunted gene expression in viral vector mediated gene therapy. To understand the problem of the immune responses, we have developed an in-vitro co-culture system with human NK cell line, macrophages and airway epithelial cells. We showed that small molecule blockers, CAPE and ruxolitinib, for NF-κB and JAK-STAT pathways, respectively, significantly inhibited cytokine secretion by macrophages. When NK cells are co-cultured with helper-dependent adenoviral (HD-Ad) vector activated macrophages, IFN-γ cytokine expression by NK cells increased significantly, which was inhibited effectively by ruxolitinib and CAPE, and there was an additive effect when both inhibitors were used. We demonstrated that NK cells activated by cytokines produced by HD-Ad-activated macrophages kill HD-Ad vector transduced bronchial epithelial cells. This cell killing activity was significantly reduced by CAPE and ruxolitinib. Combination of these two inhibitors had an additive effect on inhibiting NK cell mediate killing of gene transduced cells. Transient inhibition of NK cell response at its peak may enhance sustained gene expression. Our data suggest that combination of CAPE and ruxolitinib may help in protecting gene transduced airway epithelial cells to prolong transgene expression