Innate Immunity and the Paradoxes of Viral Pathogens and Tissue Injury in Gene Therapy

Size: px

Start display at page:

Download "Innate Immunity and the Paradoxes of Viral Pathogens and Tissue Injury in Gene Therapy"

Barry Chambers
5 years ago
Views:

1 Innate Immunity and the Paradoxes of Viral Pathogens and Tissue Injury in Gene Therapy Daniel R. Salomon, M.D. Department of Molecular and Experimental Medicine The Scripps Research Institute

2 Tissue and Cell Injury as a Paradigm for Gene Therapy Many gene delivery vectors are built on pathogen skeletons, some still with pathogen genes Many strategies for delivery of therapeutic gene cause direct tissue injury Injection/Inhalations Ex vivo cell separations and manipulations By nature, therapeutic gene delivery will often alter the state of the target cell and/or the host Changes in cell state (activation, metabolic stress, increased protein expression, promoter-driven signaling) may lead to danger signals

3 Immunity and Tissue Injury Trauma Surgery Infection immature Healthy tissue DC Tissue Injury/Inflammation mature DC Healthy tissue Effector cells: T, B, NK Chemokine Gradients APC PMN PMN APC Proinflammatory Cytokines Draining LN T/B Blood vessels T B T B T T Adaptive Responses

4 Innate vs. Adaptive Immunity Innate immunity is the first line of response to acute injury and invasion Primitive Based on pattern recognition receptors No memory Adaptive immunity represents a complex system that responds to specific antigens Evolves Determines Self vs. Non-self recognition Memory

5 Toll-like receptors and their ligands LPS/endotoxin ssrna Bacterial/Viral DNA

6 Innate Immune Receptors Toll-like Receptors 1-10 Endotoxin, dsrna, ssrna, CpG DNA, flagelin, mannose-alginate etc. CD14 Endotoxin, peptidoglycans CD36 + TLR2 Di-acyl lipopeptides and lipoteichoic acid DC-SIGN FMLP Receptor Dectin 1 Scavenger Receptors Mannose Receptor

7 Pathogens/Cellular Injury Innate Immunity Epithelial barriers B cells Adaptive Immunity Antibodies Phagocytes/PMNs Dendritic Cells T cells Effector T cells NK Cells Hours Days Time after infection

8 Link between innate and adaptive immunity Microbial/Viral Pathogens Mature DC IL-4 TH2 Naïve T TLRs Chemokine receptors Signal Processing Immature DC MHC Costimulatory molecules IL-12 TH1 Lymphoid tissues Peripheral tissues

9 Innate Immunity is Good Activation of innate immunity in the context of therapeutic vaccines leads to enhanced adaptive immunity Local Systemic Bestowing a competitive advantage on gene modified cells could enhance selection of healthy over diseased cells

10 Link between innate immunity and immune regulation Resting Pathogen/Injury Activated DC APC DC APC CD4+T Proinflammatory Cytokines: TNF, Interferons, IL1, IL6, IL12 etc. CD4+ T Foxp3 T Reg Suppression T Effector

11 Innate Immunity is Bad Any tissue injury created at a transplant site will trigger a cascade Viral proteins expressed by target cells are signals for destruction Significant alterations in cell state can target cells for destruction When innate immunity is triggered, adaptive immunity can follow

12 Directions Forward for Gene Therapy #1 Basic research The working box needs to be enlarged to include innate immunity Much remains to be discovered about triggering and regulating innate immunity Impact of different gene delivery strategies on tissue injury must be studied including dose Impact of different gene delivery strategies on cell state must be studied Different tissue compartments may have different rules Innate immunity must be considered in new vector designs - not just viral genes but promoter selections Potential of manipulating innate immune reactions must be studied - enhancing or inhibiting

13 Directions Forward for Gene Therapy #2 Clinical Applications Any strategy to limit tissue injury during gene delivery Corticosteroids Anti-inflammatory agents Anti-cytokine antibodies (anti-tnf) New generation of innate immune suppressors For therapeutic vaccines, potential strategies to enhance dendritic cell activation (TLR agonists - imidazoquinolines, LPS equivalents, cytokines) Expand the box for immune monitoring of clinical trials to include innate immune markers (cytokines, altered T or B cell activation, tissue injury)

2. Innate immunity 2013

2. Innate immunity 2013 1 Innate Immune Responses 3 Innate immunity Abul K. Abbas University of California San Francisco The initial responses to: 1. Microbes: essential early mechanisms to prevent, control, or eliminate infection;