BACKGROUND:   The innate immune system is capable of recognizing a wide variety of pathogens and rapidly induces a number of antimicrobial and inflammatory responses. Toll- like receptors (TLRs) play a critical role in innate immunity by recognizing structurally conserved motifs on these pathogens called pathogen-associated molecular patterns (PAMPS). Ten TLRs have been cloned in mammals, and each receptor appears to be involved in the recognition of a unique set of PAMPs. Upon ligand binding, TLRs have been shown to activate a variety of signaling pathways involved in antiviral, antibacterial, anti-inflammation, and anti-tumor activities. As a result, several new targets for potential pharmacologic modulation have been identified. The challenge, however, is to choose a target with important biological function and to develop systems that enable the selection of modulating agents with greater specificity and fewer side effects.

INNOVATION:   Dr. Genhong Cheng and his collaborators at UCLA have described in detail a complex signaling and gene expression network specific to Toll-like receptor 3 (TLR3) and Toll-like receptor 4 (TLR4). TLR3 and TLR4 are known to mediate the response to viral-associated PAMPS. In the papers referenced below, the investigators show that these receptors can specifically activate signaling pathways that render cells more resistant to viral infection. Thus, this invention discloses a method for treating viral diseases by targeting TLR3/TLR4 function.

But ligand binding to TLR3 and TLR4 also triggers antibacterial, anti- inflammatory and anti-tumor activities as well. To permit the screening of pharmacologic agents that specifically trigger one or more of these responses, Dr. Cheng has developed four different cell-based assays with distinct physiological readouts for antiviral, antibacterial, anti-inflammatory and anti-tumor growth activities. These assays are currently scaled up to a 384-well microtitre plate format. With these assays it is possible to screen for pharmacological agents that specifically activate (or suppress) one or more desired activities but not the others. For example, it is possible to screen for an antiviral agent that does not trigger an undesirable inflammatory response. Screening of compounds with these assays is currently underway in Dr. Cheng's laboratory.

ADVANTAGES

1. The general method of modulating TLR3/TLR4 pathways to induce antiviral, antibacterial, anti-inflammatory and anti-tumor responses is protected by a PCT patent application designating all member countries and regions (PCT/US03/12751).

2. Four distinct cell-based assays have been developed that may be used to screen for pharmacologic modulators of TLR3 and TLR4. Each assay has a distinct biologically-relevant reporter to detect antiviral, antibacterial, anti- inflammatory, and antitumor activities. The assays have been scaled up to the 384- well microtitre format.

3. The assays may be used in combination to screen for agents with one or more desired effects, or the absence of unwanted side effects. For example, it is possible to screen for agents that exhibit antiviral but not anti-inflammatory activities.

4. The invention teaches how to identify compounds that address four major medical markets: antiviral, antibacterial, anitinflammatory, and antitumor agents.

5. The methods and assay systems of the invention may also be used to identify immune adjuvants, since activation of TLR3 or TLR4 would enhance the immune response during immunization.

6. Initial drug screening is underway in Dr. Cheng's laboratory at UCLA. Therefore, the opportunity to collaborate with the inventor to identify lead compounds is available.

APPLICATIONS

Antivirals
Antibacterials
Anti-inflammatory agents
Anti-tumor agents
Immune adjuvants

DEVELOPMENT TO DATE:  The investigators identified a subset of genes that is specifically induced by stimulation of TLR3 or TLR4 but not by TLR2 or TLR9. Further gene expression analyses established that upregulation of several primary response genes was dependent on NF-kB, commonly activated by several TLRs, and interferon regulatory factor 3 (IFR3), which was found to confer TLR3/TLR4 specificity. Also identified was a group of secondary response genes, which are part of an autocrine/paracrine loop activated by the primary response gene product, interferon-beta (IFNb). Selective activation of the TLR3TLR4-IRF3 pathway potently inhibited viral replication. These results suggest that TLR3 and TLR4 have evolutionarily diverged from other TLRs to activate IRF3, which mediates a specific gene program responsible for innate antiviral responses. TLR3/TLR4 specific activation, therefore, may be a therapeutic strategy to enhance innate immunity to bacterial and/or viral infection.

Related Papers (Selected) Toll-like receptor 3 mediates a more potent antiviral response than toll-like receptor 4 [more] IRF3 mediates a TLR3/TLR4-specific antiviral gene program. Immunity, 17, 251-263, 2002 [more]

Reference: UCLA Case No. 2002-422

US Patent Number: WO 03090685