New Directions in Therapy for Sjogren’s Syndrome Robert I. Fox, MD., Ph.D. Scripps-Ximed La Jolla, CA (all slides on my website

Background Benign Symptoms These do not correlate well with acute phase reactants They are more similar to “neuropathic” symptoms and involve “nociceptive” pain circuits Nociceptive pain is caused when special nerve endings—called nociceptors –are activated and follow a particular pathway to cortex of brain

Use of Biologics in Systemic Manifestations of SS We have had modest success with biologics as measured by ESSDAI (clinical significance >3 units improvement) in SS patients with early disease Rituximab Belimumab Abatacept Tocilizumab

Background-2 The functional Circuit To understand “benign symptoms” and develop better therapies—we must review the concept of the functional circuit in SS the interaction of immune activation on microglial cells and associated neurons New targets include mTor and AKT pathways

Background-3 The functional circuit in SS 1. Mucosal Surface (inflammatory cytokines and metalloproteinase) 1. Mucosal Surface (inflammatory cytokines and metalloproteinase) 2. Midbrain Vth Nucleus (lymphocytes and glial cells) 2. Midbrain Vth Nucleus (lymphocytes and glial cells) 4. Gland (lymphs, cytokines, metalloproteinase) 4. Gland (lymphs, cytokines, metalloproteinase) 3. Vascular (iNOS, CAMs, Chemokines) 3. Vascular (iNOS, CAMs, Chemokines) Brain Cortex Nociception (pain) glial cells and corticcal neurons Brain Cortex Nociception (pain) glial cells and corticcal neurons These sites and their cytokines correlate with systemic manifestations We must understand these sites to treat “benign” symptoms

Does this apply to Sjogren’s syndrome? Patients with early SS had corneal pain that decreased completely with topical anesthesia* Patients with chronic SS showed only a partial (30% decrease) in eye pain after topical anesthetic* Functional MRI (fMRI) showed nocioceptive pattern—called phantom pain amplification *Rosenthal et al

To study the mechanism of neurogenic or nociceptive pain we must use animal model-1 The thrombospondin (-/-) mouse (TSP null) or the TGF-  receptor mutation both develop SS like disease The mouse develops both oral and ocular lesions The mouse develops ANA and SS-A antibodies Thrombospondin is a matrix protein that plays a role in activation of latent TGF-  Activated TGF-  promotes Treg and inhibits Th-17 (IFN-  Thus, TSP (null) has high levels of Th-17, IL-17 and IFN- 

Thrombospondin (-/-) mouse model of SS 4 wks Lacrimal gland biopsies The mouse has ANA+, SS-A+ TSP null can not activate TGF-  In absence TGF-  continuous Th-17 TGF-  and cytokine activation stimulates mTor/AKT WT Tsp-/- 24 wks

Thrombospondin (-/-) Mouse at 24 wks Where a trivial stimuli Causes pain response Wild type A pain stimuli that is innocuous in Wild Type does cause nociceptive pain in tsp (-/-) mouse model The Pain Threshold is Lowered in the Tsp (-/-) mouse Ocular chemical stress model of nociceptive pain Le Bars D, Animal models of nociception. Pharmacological reviews 2001;53:

At the level of the Vth nerve (Tsp -/- mouse) Microglial cells translate inflammatory signals that go to nociceptive cortex WT TSP (-/-) mTor and AKT activated in response to “lower stimuli” in the tsp (-/-) mouse

Of interest, the same regions are activated with physiologic or emotional stressors Emotional Physiological Similar pattern of Fos-ir in cortical neurons in response to distinct stressors

Summary-1 Functional circuit needs to be considered when assessing “benign” symptoms of corneal or oral pain Symptoms of oral/ocular pain do not correlate with markers of systemic inflammation (ESR/CRP) because the events are contained within the brainstem and cortex

Summary-2 Afferents go to midbrain regions of Cranial Vth Microglial cells are site of cytokine/neurokine interaction Receptors and neurokines from microglial cells are therapeutic targets

Summary-3 Novel targets include mTor and AKT pathways These mTor/AKT pathways also implicated in chronic pain and depression—so we must collaborate with these neurochemists

Summary-4 Cortical “memory” of nociceptive pain is well described in neurologic literature fMRI indicates that nociceptive pain is the cause of benign symptoms in SS that do not correlate with acute phase reactants

Moulton et*. Al used fMRI in SS patients with chronic ocular pain using fMRI of nociceptive pain have been studied Cortical regions that activate with ocular pain signal at “benign stimuli levels” occur only in chronic SS patients with severe pain *Moulton EA, Becerra L, Rosenthal P, Borsook D. An Approach to Localizing Corneal Pain Representation in Human Primary Somatosensory Cortex. PloS one 2012;7:e44643.

Summary-5 We have made advances in “systemic inflammation” and these are encouraging For “drug licensing” we will also need to improve the patient’s “quality of life” symptoms of dryness, pain and fatigue We need for “autoimmune” divisions to work with “neuro-chemistry” research divisions

We are also looking at Additional Targets of Interests Chemokines and their receptors (CCR) on vascular cells and lymphocytes TLR receptors: SLAC-15 that links Toll receptor and type 1 IFN Methylation modulators and siRNA Neural mediator circuits: Receptors on cornea--substance P (TRPV1), VIP and CGRP pain receptors TRPM8, TRPA1, and CGRP in trigeminal ganglion neurons Trigeminal ganglion neurons- MCP-1, MIP-2, CCR and CCL at the blood brain barrier

CCR and Blood Brain Barrier

Emotional Physiological Similar pattern of Fos-ir in PVH neurons in response to distinct stressors

We need to examine microglial pathways Upon activation, microglia (M1 and M2) secrete inflammatory mediators that contribute to the resolution or to further enhancement of damage in the central nervous system (CNS). Particularly, the role of the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and glycogen synthase kinase-3

The tsp-null mouse allows us to look at the interaction of peripheral inflammation and microglial cells Activation of microglial cells through mTor/AKT In absence of thrombospondin, constitutive activation of Th17 and IFN-  activates microglial cells Nociceptive (pain) pathway occurs through smad3 and non-smad pathways that involve mTor/AKT pathways in cranial nerve V