INCORPORATION OF SEQUENCE LISTING

A computer readable form of the Sequence Listing containing the file named “IURTC_2017-116-08_ST25.txt”, which is 1,160 bytes in size (as measured in MICROSOFT WINDOWS® EXPLORER), is provided herein and is herein incorporated by reference. This Sequence Listing consists of SEQ ID NOs: 1-4.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates generally to methods of reducing neuronal sensitivity, thereby reducing inflammation and chronic pain. Particularly, it has been found herein that by enhancing the DNA base excision repair (BER) pathway, through the administration of APX3330, neuronal sensitivity to inflammatory mediators is reduced, thereby alleviating inflammatory or chronic pain.

Inflammatory mediators, released from damaged tissue and immune cells during damage, can have acute and chronic effects on the sensitivity of primary sensory neurons. Prostaglandins, bradykinin, histamine, serotonin, tryptases, cytokines, and ATP can alter the sensitivity of sensory neurons to various stimuli via posttranslational modifications of ion channels that contribute to the depolarization of sensory neurons (see Richardson and Vasko, 2002). These inflammatory mediators enhance kinase activity, resulting in the phosphorylation and modulation of ion channels to alter neuronal sensitivity. Peripheral sensitization is a key component of inflammatory diseases and chronic pain syndromes. This sensitization manifests as hyperalgesia and allodynia in humans and as hypernociception in animal models of pain. Although acute hypersensitivity after injury is an important component of the inflammatory response that aids in protecting the injury, there is oftentimes a maintenance of this hypersensitivity beyond the time required for tissue repair.

In addition to the widely studied effects of inflammatory mediators on kinase activity, there is an increase in the production of reactive oxygen (ROS) and nitrogen species (RNS) during inflammation and in animal models of chronic neuropathic pain (Bauerova and Bezek, 1999, Babior, 2000, Kim et al., 2004, Remans et al., 2005, Fidanboylu et al., 2011, Salvemini et al., 2011). This maintained sensitivity underlies many persistent inflammatory and chronic pain conditions, which are difficult to treat with current therapies. In particular, several studies have suggested a reversal of neuronal sensitivity with antioxidants (Khattab, 2006, Keeble et al., 2009, Fidanboylu et al., 2011, Duggett et al., 2016), yet there are deleterious effects of global antioxidant treatment due to the ubiquitous role of ROS/RNS in cellular signaling and cellular redox homeostasis (see Martin and Barrett, 2002). An important consequence of ROS/RNS production in sensory neurons is oxidative DNA damage. Indeed, previous studies demonstrated that ROS/RNS and subsequent DNA damage mediate changes in neuronal sensitivity induced by cisplatin, oxaliplatin or ionizing radiation in cultures derived from dorsal root ganglia (Jiang et al., 2008a, Vasko et al., 2011, Kelley et al., 2014).

The repair of DNA damage is critical for the maintenance of neuronal homeostasis (Brooks, 2002, McMurray, 2005, Fishel et al., 2007a, Hetman et al., 2010), as endogenous metabolic activity, oxidative stress secondary to injury (Kruman and Schwartz, 2008), environmental toxins, (Kisby et al., 1999) and drugs (Ahles and Saykin, 2007) all can cause neuronal DNA damage. Neurons contain the major DNA repair pathways including base excision repair (BER), nucleotide excision repair, mismatch repair, direct damage repair, and nonhomologous end-joining or homologous recombination (Fishel et al., 2007b, Barzilai et al., 2008, Fortini and Dogliotti, 2010). The BER pathway repairs DNA damage in the nucleus and mitochondria, caused by oxidative damage to bases, alkylation of bases, or deamination, and is likely the most important repair pathway for protecting neurons. The first step in BER is removal of the incorrect or damaged base by a DNA glycosylase. The second step in the BER pathway involves the enzyme APE1, which hydrolyzes the phosphodiester backbone immediately 5′ to an apurinic/apyrimidinic (AP) site. This generates a normal 3′-hydroxyl group and an abasic deoxyribose-5-phosphate, which is processed by subsequent enzymes of the BER pathway.

As current therapies have limited efficacy and can result in significant side effects, determining the mechanisms for maintaining peripheral sensitization and using that information to design new therapies for treating inflammatory and chronic pain is clinically significant. Accordingly, the present disclosure provides insight into the pathway by which inflammatory mediators sustain changes in neuronal sensitivity and highlights the enhancement of neuronal DNA repair as a pharmacological target to alleviate inflammatory and/or chronic pain. Further, the present disclosure provides a compound, APX3330, to enhance DNA repair and reduce neuronal sensitivity.

BRIEF DESCRIPTION

The present disclosure relates generally to methods of reducing neuronal sensitivity, thereby reducing inflammatory and chronic pain. Particularly, it has been found herein that by enhancing the DNA base excision repair (BER) pathway, through the administration of APX3330 (and/or analogs thereof), neuronal sensitivity to inflammatory mediators is reduced, thereby alleviating inflammatory or chronic pain.

Based on the foregoing, in one aspect, the present disclosure is directed to a method of reducing neuronal sensitivity in a subject in need thereof. The method comprises administering to the subject an effective amount of an apurinic/apyrimidinic endonuclease 1 redox factor 1 (APE 1/Ref-1) inhibitor, pharmaceutically acceptable salts or pharmaceutically acceptable solvates thereof, which selectively inhibits the amino terminal portion of APE 1.

In another aspect, the present disclosure is directed to a method of treating inflammation and chronic pain in a subject suffering from diabetes. The method comprises administering to the subject an effective amount of an apurinic/apyrimidinic endonuclease 1 redox factor 1 (APE 1/Ref-1) inhibitor, pharmaceutically acceptable salts or pharmaceutically acceptable solvates thereof, which selectively inhibits the amino terminal portion of APE 1.

In yet another aspect, the present disclosure is directed to a method of enhancing neuronal DNA repair function in a subject suffering from diabetes. The method comprises administering to the subject an effective amount of an apurinic/apyrimidinic endonuclease 1 redox factor 1 (APE 1/Ref-1) inhibitor, pharmaceutically acceptable salts or pharmaceutically acceptable solvates thereof, which selectively inhibits the amino terminal portion of APE 1.

